1985 LIBR ARY 7 61 CONTENTS Hydrolysis of Cellulose in Wood with Concentrated Hydrochloric Acid in the Presence of L ithium , Calcium and Zinc , by I.S. GOLDSTEIN , J.M. SINGH and F. BAYAT MAKOOI - The Colloid Chemistry of Waste Paper , by A . LARSSON , P. STENIUS and Deinking L . Chemical Ch ara x 5 7 The Influence of NaOH and Na SO 3 on the Quality of Chemithermomechanical Pulps of Hardwoods , by K.N. LAW , M. LAPOINTE and J.L. VALADE Studies of the Impregnation of Birch Us i ng Scanning Electron Microscopy and Energy Dispersive X Ray Analysis , by G. BENGTSSON , R. SIMONSSON , C. HFITNER , R.P. BEATSON and C.A. FERGUSON 57 - 3 I The French E xploded Wood Project , by D. LACHENAL and P. MONZIE 55 - 1 ' ct arization of Kraft Lignin Products , by B.F. GRIGGS , and Kraft L i gnin J.S. GRATZI C L. CHEN and A. VENICA Enzymatic Hydrolysis of Pretreated Wood to Fermentable Sugars Using Cellulases from Trichoderma harzianum , by J.N. SADDLER , C. BREUIL , M . MES HARTREE L • TAN and E.K.C. YU lkaliand Macromolecular Characteristics ot A Organosolv Lignins from Black Cotton by F. PLA , M. DOLK , J.F. YAN and J.L. MCCARTHY od , wo 65 Why Does Chlorination and Extraction Fail to Delignify Unbleached Kraft Pulp Completely ? , by R.M. BERRY and B. I. FLEMING. 2 9 Sulphite Promoted De l ignlfication , by N.G. LEWIS , H. BRADFORD , A.M. BIALSKI an d C.E. LUTHE 79 13 Thioacidolyse des lignines: n ouvel le m éthode de caractdrisation des Alkyl Aryl Ethers , by B. MONTIES, C. LAPIERRE and C. ROLANDO 81 Study on Mechanisms of Kraft and Magnesium Sulphite Delignification of Bagasse with SEM - EDXA , by J X. CHEN and G X. WU 21 Reactions of Phenylcoumaran Lignin Model Quinone Methides with AHQ/ Anthranol , by J. RALPH and R.M. EDE 83 The Multiform Nature of Residual Lignin in Chemical Pulps , by J. SUNDQUIST 23 Hydrodynamic Aspects of Polymer Bonding in Papermaking , by T.G.M. VAN DE VEN .. 8 27 Effect of Anthraquinone on the Alkaline Degradation of Polysaccharides , by A.F.A. WALLIS and R.H. WEARNE 89 - Study of Lignin Structure by Silicon 29 NMR Spectroscopy , by R BREZNY , J. SCHRAML , M. KVICALOVA , J. ZELENY and V. CHVALOVSKY . . Delignification Using Hydrogen Peroxide and Oxygen Under Acidic Conditions The POs Treatment , by H.U. SUSS and H. KRUGER . - - - - 11 - - Acid Base Interactions Between Cellulose and Organic Molecules , by A. LARSSON and I P. STENIUS Dissolution Mechanism of Cellulose in the SO 2 Diethy 1amine Dimethy 1 sulfoxide System , by A. ISHIZU , A. ISOGAI and J. NAKANO - - Effect of Explosion Operation for Effective Utilization of Plant Material , by T. SAWADA , Y. NAKAMURA and M. KUWAHARA Harmonizing Bleaching Technology with Future Environmental Regulations, by A. de RUVO - 29 Acetyl Xylan Esterases A Novel Class of Microbial Enzymes Involved in the Degradation of Hemicellulose , by P. BIELY , C.R. MACKENZIE, J. PULS and H. SCHNEIDER ... - 31 Less Ordered Regions (LOR ) of Cellulose New Chemical Approaches , by M. LEWIN 37 Mass Loss of Wood and Its Components during Transmission Electron Microscopy , by J F. REVOL , M. MARY and D.A.I. GORING - - On the Raction Between Alkylketene Dimers ( AKD) and Cellulosic Fibres, by L. ODBERG and T. LINDSTROM 7 93 95 97 Biological Pulping , by K E. ERIKSSON and S.C. JOHNSRUD 101 Chemically Modified Ligninfor the Use in Controlled Release Devices , by A.H.A. TINNEMANS , H.F MARTENS , G.J. VAN VELDHUIZEN and P J. GREIDANUS . 105 Rotating Felt to Study the Behaviour of Organic Colloids in Papermaking Stock , by A OK AG AW A and T FUKUI . 109 Chemical Structure and Reactivity of the Middle Lamella Lignin , by U. WESTERMARK 113 Pathways and Mechanism of Degradation for ArylGlycerol Aryl Ether Substructure Models by Phancrochaete chrysosporium and Coriolus versicolor , by T. HIGUCHI , M. SH I MADA , T. UMEZAWA and K. RAWAI 117 Cellulose Suspensions and Polyelectrolytes Some Kinetic Aspects, by T. LINDSTROM 121 41 -- De l ignification of High Yield Sulphite Pulp with Alkali , by N S. CHO Degradation of Chlorinated Lignin and Chlorinated Organics by a White Rot Fungus , by Y. MATSUMOTO , C.F. YIN , H M. CHANG , T.W. JOYCE and T.K. KIRK - - 43 45 - Catabolic System of Lignin Related Model Compounds by Pseudomonas sp. TMY 1009 Strain , by M. SAMEJIMA , Y . SABURI , T. YOSHIMOTO , T. NAKAZAWA and T. FUKUZUMI 13C NMR of Lignocellulosics , by M.G. TAYLOR and R.H. MARCHESSAULT 47 49 U l trastructural Modifications of Wood After Degradation by Sporotrichum pulverulentum and its Mutants , by J P. JOSELEAU and - K. RUEL Characterisation of Lignin Structures in Whole Wood by Carbon 13 CP/ MAS Nuclear Magnetic Resonance , by R.H. NEWMAN , K.R. MORGAN and G.J. LEARY 51 - 53 - . . . . -ÿ - - - Analysis of Polyphenol Derived Aromatics in Wood , by A . F.A. WALLIS , C.P. GARLAND , P.J. NELSON and F.C. JAMES 123 Oxygen Bleaching Following Preoxidation of Wood Pulp with N02/O , by O. SAMUELSON ... 127 2 Investigation on Lignins and Lignin Polymer Models by FTIR Spectroscopy , by 0. FAIX .• •. 133 The Action of Gaseous Chemicals on Structural Timber , by G. WEGENER and D. FENGEL 135 Chemimechanical Pulp from Jack Pine by Sulphite /Quinone Pulping , by C.H. TAY and S.E. IMADA 137 Fermentation of Spent Sulphite Liquor to Butanol and Ethanol , by M. WAYMAN and S. YU. 145 - Flavologlycans Major Constituents of Forestry Materials? , by G.N. RICHARDS 147 The Reactions of Alkaline Hydrogen Peroxide with 1 , 2 Diary l l ,3 Propanediols , by C.W. DENCE and A.J. NONNI 149 Characterization of Wheat Straw Lignin , by Z.Z. LEE and X.Q. PAN 153 - - - An Electron Microscope Study of Attack on Straw by Pan us conchatus , by H S. YU , Y Z. XING , W L WANG and Y J. TAO - - -. - - - 165 - The Effect of Cobalt Complexes on Oxygen Alkali Delignification of Asplund Pulp , by S. MEGURO , K. SAKAI and H. IMAMURA ... 167 Organic Acid Pulping of Wood. Part I. An Overview of Applications , by R.A. YOUNG , J.L. DAVIS , E B. WIESMANN and K.W. BAIERL •• 169 - Studies on Wood Fibre Structure Using Bioloqica l Decay Organisms , by G. DANIEL and T. NILSSON - 173 - Wood Degrading Bacteria New Microbes for Bioconversion of Lignocellulose , by T. NILSSON and G. DANIEL A Comparative Study of Organosolv and Kraft Pulps , by M. CRONLUND , J.H. LORA , J. POWERS, G. ORLOWSKI and L. WU 181 183 - End Wise Degradation of Hydrocellulose in Mildly Alkaline Solutions and its Retardation by Ammonia , by V.L. CHIANG and K.V. SARKANEN Wood Chemistry for Fun and Profit , by D.A.I. GORING Leac hing of Lignin and Carbohydrate from Chem mechanical Pulps , b y J . M . WILLIS and D.A.I . GORING Biological , Chemical , and Te chn Wood Investigations f om Pollu tion Trees, by J. PULS , P. RADEMACHER H. GOTTSCHE KÜHN , J. BA UCH andA - r 185 189 Sulphite Treatment of Aspen. Factors Affecting the Formation of Carboxylate and Sulphonate Groups , by R.P. BEATSON , C. HEITNER , M. RIVEST and D. ATACK 205 The Prospect of Engineering Materials from Lignin , by W.G. GLASSEK , V.P. SARAF , T.G. RIALS , S.S. KELLEY and T.C. WARD 207 Hydroxyl Radicals in Oxygen Bleaching , by M. EK , J. GIERER and T. REITBERGER 209 Enzymatic Degradation of Cellulose Cyrstals , by H. CHANZY and B. HENRISSAT 211 Structural Changes in Lignin Degradation during Steam Hydrolysis of Aspen Wood , by D.R ROBERT and M. BARDET 213 Transition Metal Ion Catalysis of the Hydrogen Peroxide Oxidation of a Lignin Model Compound , by P.K. SMITH and T.J. MCDONOUGH 215 Reaction of Aspen and Southern Pine Wooa Flakes with Gaseous Ketene , by J.A. HYATT, R.H.S. WANG and R.M. ROWELL 221 . Comparison Between Lignins Produced by Steam Explosion and Organosolv Pretreatments, by H.L. CHUM , D.K. JOHNSON , M. RATCLIFF , S. BLACK , H.A. SCHROEDER and K. WALLACE 223 Reactions of Glycosides with Borate Ions at Elevated Temperature , by J. JANSON .. 227 Influence of Divalent Metal Salts on Anthraqumone Pulping , by M.S. STELTENKAMP . 229 - Acos Accelerated Hydrolysis of Wood by Acid Catalysed Organosolv Means , by L. PASZNER , A.A. QUINDE and M. MESHGINI . 235 - Microcomputer Based Image Processing as Applied to Evaluation of Surface Phenomena of Paper Sheets and Pulp Suspensions, by F. ONABE 241 Ligninase from Phanerochaete chrysosporium: Catalvtic Properties of a Novel Enzyme , by T.K. KIRK , M. TIEN , K.E. HAMMEL, P. KERSTEN and B. KALYANARAMAN 243 An Assessment of Priorities in biomass Research , by K.V. SARKANEN 249 175 Electron Transfer Reactions in Pulping Systems , by D.R. DIMMEL and L.F. PERRY . . . .. 177 Biotechnological Methods for Valorization of Bark Wastes , by A.M. DESCHAMPS ylan in its K. POUTANEN , LINKO X 155 The Structural Modification of Lignin during Oxygen Bleaching , by G. GELLERSTEDT, K. GUSTAVSSON and E. LINDFORS 159 On the Reaction of Softwood Type and Hardwood Type Lignin Model Compounds during Alkaline Pulping , by R. KONDO, Y. TSUTSUMI and H. IMAMURA - The Role of Side Chains of Diotechnical Uti li zation , J. PULS , L. VIIKARI and K. 191 201 ological - Affected FRÜHWALD. 20 3 . The Topochemistry of Acid Sulphite Pulping: A Theoretical Analysis Part II , by H.I. BOLKER and R.M BERRY 251 Hydrogen Peroxide Decomposition by Metal Catalysts: Bad Actors in a Bleaching Stage , by J.T. BURTON and L.L. CAMPBELL 255 Photoacoustic Infrared Spectroscopic Study of Mechanical Pulp Brightening , by F.G.T. ST GERMAIN and D.G. GRAY 26 1 Bagasse De l ignification: Chemical Components Relations, by N. FERNANDEZ , J. SABATIER , N. ROMERO , R. GUADARRAMA , R. CRUZ and G. MIERES 263 - Organosolv Pulping with Acetic Acid , by H H . NIMZ and R. CASTEN 13 C NMR Spectra of Acetic Acid Lignins , by H H. NIMZ and D. ROBERT . 265 . 267 Interpretation in Chemical Terms of Some Selectivity Problems During Pulping and Bleaching , by J. GIERER 269 Comparison of Pretreatment Methods for Enhancing the Enzymatic Hydrolysis of Wood , by H H. BROWNELL 271 . Detection , Prediction , Synthesis and Confirmation of a Mutagen , by G. STR UM LLA, I. JOHNSON, B. ISACOVICS and H. RAPSON ... 273 The Kinetics of Sulphonation Reactions on Norwegian Spruce , by P. ENGST RAND , L- A. HAMMAR and M. HTUN 275 Ultra -High Yield Pulps from Hardwood , by T. GRANFELDT and R. SIMONSON 281 A Mathematical Model for the Ultrafiltration of Pulp Mill Effluent Liquors , by D.L . WOERNER and J.L. MCCARTHY 283 The Catalytic Hydrogenolysis of Wood and Isolated Lignins , by J.M. PEPPER and M.D. RAHMAN 28 7 Nitrobenzene Oxidation of Ground Wood Lignin , by M. SUMIMOTO and H. HIRASHIMA .. .. 289 Effect of Ethanol on Soda -Anthraquinone Pulping , by G.M. De CHACON and Y-Z. LAI 291 INDEX TO AUTHORS ATACK , D. 191 BAIERL, K.W. ... BARDET, M BAUCH , J BAYAT- MAKOOI , F. BEATSON , R.P. .. BENGTSSON , G. .. BERRY , R.M BIELY , P BLACK , S BOLKER , H.I. ... BRADFORD , H. ... BREUIL , C BRE Z.NY , R BROWNELL, H.H. . BURTON . J.T. ... 169 213 203 1 57 ,191 57 7 1, 2 5 1 93 223 251 79 55 11 271 255 . CAMPBELL, L.L CASTEN , R. .. CHANG , H - M. . CHANZY , H. .. CHEN, C L .. CHEN , J - X. .. CHIANG , V.L. . . . . . . . . . . . . . . CHO , N -S. ... CHUM , H . L. .. CHVALOVSKY , V. CRONLUND, M. . CRUZ , R. 255 265 45 211 -. DANIEL , G. . . .. . . . . . .. 5 21 185 43 223 11 181 263 173,175 169 DAVIS , J.L De CHACON , G. M De RUVO , A. .. DE NCE , C.W. .. DESCHAMPS , A . M DIMMEL, D.R. . DOLK , M 291 37 149 183 177 65 EDE, R.M EK , M ENGSTRAND , P. ERIKSSON , K - E. 83 209 275 101 FAIX , P. FENGEL , D. FERGUSON C.A FERNANDEZ , N. FLEMING , B. I. FRÜ H WALD , A . FUKUI , T. ... FUKUZUMI , T. 133 135 57 26 3 71 203 109 47 GARLAND , C.P. ... GELLERSTEDT , G. . GIERER , J GLASSER , W.G. . . GOLDSTEIN , I.S. . GORING, D.A.I. . GOTTSCJIE- KUHN , H. GRANFEL DT , T. . . GRATZL , J S GRAY , D.G GREIDANUS , P.J. . GRIGGS , B.F GUADARRAMA , R. . GUSTAVSSON , K. . . . . . .. 123 159 209 , 269 207 1 97 ,189, 201 203 281 5 261 105 5 263 159 HAMM AR , L- A. HAMMEL , K. E. HEITNER , C. HENRISSAT B. HIGUCHI, T. . HI RASH IMA , H HTUN , M HYATT , J.A . . 275 243 57 ,191 IMADA , S.E.. . IMAMURA , H. . ISACOVICS, B. ISHIZU , A. .. ISOGAI , A . .. 137 165, 167 . 211 117 289 275 221 273 29 29 JANSON , J. ... JAMES, F.C. .. JOHNSON , D.K . JOHNSON , I. .. JOHNSRUD , S.C. JOSELEAU, J -P. JOYCE, T.W. .. KALYANARAMAN , B. KAWAI , K KELLEY , S.S. ... KERSTEN , P KIRK , T.K KONDO, R KRUGER , E KVICALOVA , M. .. LACHENAL , LAI , Y - Z. LAPIERRE , C. LAPOINTE , M. LARSSON , A. . LAW, K LEARY , G.J. . LEE, Z.Z. ... LEWIN , M. ... LEWIS, N.G. . LINDFORS , E. LINDSTROM , T. LINKO , M. ... LORA , J.H. MACKENZIE , C. R. . MARCHESSAULT, R .H MARTENS, H .F. ... MARY , M MATSUMOTO , Y. ... MCCARTHY , J.L. .. MCDONOUGH , T.J. . MEGURO , S MES-HARTREE , M. . MESHGINI , M MIERES , G MONTIES , B MONZIE , P MORGAN , K. R 227 123 223 273 101 51 45 243 117 20 7 243 45, 243 165 13 11 7 291 81 9 3, 27 9 53 153 95 79 159 121 205 181 93 49 105 97 45 65, 283 215 167 55 235 263 81 7 53 NAKAMURA , Y. NAKANO , J. . NAKAZAWA , T. NELSON , P.J. NEWMAN , R. H. NILSSON , T. NIMZ , H. H. . NONNI , A • J. 123 53 173,175 265 , 267 149 ODBERG , L. . OKAGAWA , A. ORLOWSKI , G. 3, 41 109 181 PAN , X.Q. .. PEPPER , J. M. PERRY , L.F. PLA , F POUTANEN , K . POWERS , J. . PULS , J. ... 153 RADEMACHER , P. RAHMAN , M.D. . RALPH , J RAPSON , H. ... RATCLIFF , M. . REITBERGER , T. REVOL, J.- F. . RIALS , R G . RICHARDS , G. R I V E S T , M. . R O B E R T , D. R ROLANDO , C ROMERO , N. ROWELL , R M . . . . . RUEL, K. ... 31 29 47 287 177 65 205 181 93, 203, 205 203 287 83 273 223 209 97 207 147 19 1 213, 267 81 263 221 51 . SABATIER, J ... SABURI , Y SADDLER , «J • N. .. SAKAI , K SAMEJIMA, M. ... SAMUELSON , P. .. SARAF , V.P SARKANEN , K V. .. SAWADA , T SCHNEIDER , H. ... SCHRAML, J SCHROEDER , H.A. . SHIMADA , M SIMONSON , R SIMONSSON , R. ... SINGH , J.M SMITH , P.K ST CERMAIN , F.G.T STELTENKAMP , M.S. STENIUS, P STRUMILA , G SUMIMOTO, M SUNDQUIST, J. ... SUSS, H.U . - 263 .... 47 55 167 47 127 207 185 ,249 31 93 11 223 117 281 57 1 215 261 229 3 ,27 273 289 23 13 TAN , L TAO , Y J TAY, C.H TAYLOR , M.G. ... TIEN , M TINNEMANS, A.H.A TSUTSUMI, Y. ... 55 155 137 49 243 105 165 UMEZAWA , T. 117 - * . V ALAD E , J.L. . . . . . . VAN DE VEN , T.G.M. VAN VELDHUIZEN , G.J VENICA , A WALLACE, K. . WALLIS , A.F.A WANG , R.H.S. WANG , W L. .. WARD , T.C. .. WAYMAN , M. .. WEARNE, R.H . WEGENER , G. .. WESTERMARK , U. WIESMANN , E B. WILLIS , J.M. . WOERNER , D.L. WU , G X WU , L - . - - 9 87 105 5 223 89 ,123 221 155 207 145 89 135 113 169 201 283 21 181 XING , Y Z. - 155 YIN , C.F. ... YAN , J.F. ... YOSHIMOTO , T. YOUNG , R.A. . YU, E.K.C. .. YU , H S YU , S 45 65 47 169 55 155 145 ZELENY , J. 11 - HYDROLYSIS OF CELLULOSE IN WOOL) WITH CONCENTRATED HYDROCHLORIC ACID IN THE PRESENCE OF LITHIUM , CALCIUM AND ZINC - JAI MAL SINGH , FRED BAYAT MAKOOI AND IRVING S. GOLDSTEIN DEPARTMENT OF WOOD AND PAPER SCIENCE NORTH CAROLINA STATE UNIVERSITY RALEIGH , NC 27695 8005 weight basis, but zinc is most effective on a molar basis. The rate constant for lithium is essentially the same as thet previousl reported ; for 16 N HCi in the absence of salts ( 1 , . Table I EFFECT OF SALTS ON HYDROLYSIS OF CELLULOSE WITH 12N HCI AT 50 C ° - ABSTRACT The kinetics of hydrolysis of cellulose in wooc with concentrated hydrochloric acid ( 37% , 12N ) in the presence of lithium , calcium and zinc chlorides has been studied at moderate temperatures (20 50 C). Tne first order - ° reactions go virtually to completion in as rapidly as 10 minutes, although in the absence of tne salts cellulose is resistant to hydrolysis at this acid concentration , Otner variables studied included salt concentration , lower acid concentrations, and wood particle . The effect of the salts by weignt on rate size or hydrolysis decreases in the order Li > Zn > Ca. KEYWORDS: Cellulose , Hydrolysis , Concentrated HCI, Salts. k(min 1) ZnCl 2 (6.43) LiCl (2) CaCl 2 (5.24) -2.561 2 0.425 6 Time (min.) tor 90% hydrolysis -0.042 56 The effect of salt concentration on hydrolysis of cellulose in ground prehyurolyzec sweetgum wood ( ^63% cellulose , 37% lignin) is shown in Table II. It is apparent from the taoie that the hydrolysis of cellulose during this fixed period of time increases with increasing ratios of salt to wood , reaching more or less constant values « near a LiCl:wood ratio of 1.8:1 , CaCl :wooa 2 ratio of 2.9:1 and ZnCl :wood ratio ct 3.t : l. 2 These ratios of salt to wood were used in the subsequent experiments reported in this paper. While the optimum weight ratio of sa t to wood increases witn the molecular weight of the salts , equivalent ratios of each salt accomplished aproximately the same extent of hydrolysis. Of course , these optimum ratios are - INTRODUCTION During studies of the hydrolysis of cellulose with superconcentrated hydrochloric aciu ( 40%) in this laooratory it was found that in the presence of certain cations ( Li* , Ca + + and Zn** ) hydrolysis will proceed to completion at lower concentrations of nydrocnioric acid that are incapable of hydrolyzing cellulose in the aosence of tne sjaits (1). Similar observations were noted by fc'eardsmore (2). The effect of the variaoles ot ^ etciu Salt (g/g cellulose ) ano salt concentrations , temperature and ot agitation tor the hydrolysis of cellulose by hydrochloric acid enhanced witn lithium chloride has been recently reported (3). The present paper represents the extension only approximate since the increments tor Ca and Zn shown in Table II are quite large. Table II EFFECT OF SALTS ON HYDROLYSIS OF CELLULOSE IN PREHYDROLYZED SWEETGUM WOOD WITH 12N HCL AT 50 C ° Salt Salt/wood ratio . ( wt ) degree LiCl 1 . 0 0: 1 1.25:1 1.50:1 1.75:1 2.00:1 1.21:1 2.42:1 3.63: 1 5.13: 1 1.23:1 1.96:1 2. 4: i 3.92:1 Of these studies to the hydrolysis of cellulose in the presence of calcium and zinc and the hydrolysis ot wood in the presence of all three ZnCl 2 . cations RESULTS Cellulose (filter paper , Wiiey rnilled to pass 60 mesh ) was hydrolyzed at 50 C CaCl2 ° with 12N (37%) HCI containing 2g LiCl per g cellulose or ^ . equimolar quantities of ZnCl 2 ( t> 43g ) or CaCi 2 (5.24 g ). Table I compares tne rates ot hydrolysis. Litnium is most effective on a 1985 Wood and Pulping Chemistry Symposium W Cellulose hydrolyzed ( lhr.)( % ) 69.6 77.0 82.4 88.8 89.1 53.0 79.3 85.9 85.3 69.2 74.3 83.3 84.4 Equivalent weights corresponding to 1.8:1 for Li would be 2.4:1 for Ca and 2.9:1 for Zn. The kinetics of hydrolysis of cellulose in prehydrolyzed sweetgum wood with 37% HC1 in the presence of lithium , calcium and zinc chlorides was studied at 20°- 50 C. The results at 50 C for ground wood are shown in Table III. ° ° Table III EFFECT OF SALTS ON HYDROLYSIS OF CELLULOSE IN Table IV EFFECT OF SALTS ON HYDROLYSIS OF HOLOCELLULOSE IN SOUTHERN PINE WOOD WITH 12N HC1 at 50 C ° Salt (g/g wood ) ZnCl 2 (3.6) LiCl ( 1.8) CaCl 2( 2.9) k ( min *) Time (min) for 90% hydrolysis 0.866 5 0.221 10 0.037 55 PREHYDROLYZED SWEETGUM WOOD WITH 12N HC1 AT 5U°C Salt q/q wood ) LiiCi (1.8) ZnCl 2 (3.6) CaCLz (2.9) k(mm CONCLUSIONS *) Time ( min) for 0.200 90% hydrolysis 9 0.118 15 0.020 99 With this substrate the rates were slower tnan tor pure cellulose (TaDle I ) ana for 16 N HCl (1). Actual salt to cellulose ratios were 2.9:1 for Li, 5.8:1 for Zn and 4.7:1 for Ca. In this series, although all the rates were retarded compared to pure cellulose , tne rate with zinc was retarded to a much greater extent. Activation energies and extent of reaction followed the pattern previously reported (1, 3); high activation energies ( > 20 kcai/mol) and complete reaction for ground wooo, low activation energies and incomplete hydrolysis for chips. Additional studies were carried out at lower acid concentrations. With 30% HCl at 5U C and the same salt concentrations the rates of hydrolysis were reduced twentyfold. However with 24% HCl at 70 C the hydrolysis rates increased sharply at critical salt:wood ratios of 4:1 tor Li , 5:1 for Ca and 8:1 for Zn. Under •r . * •• these conditions 87% of the cellulose was hydrolyzed in one hour with 5.2:1 LiCl, 81% with b:l GaCl 2 and 79 % with 10:1 ZnCln. z i» * In a final study the substrate used was southern pine wood to determine the effect of the system on an unprehyarolyzea softwood. A holoceliulose content of 64% was used for the calculation of caroohydrate hydrolysis The kinetics of hydrolysis of holoceliulose was studied at 20 50 C with 37 % HCl The results with ground wood a t 50 C are shown in Table IV. In this series also the rates were retarded compared to pure cellulose, but the rate with zinc was not affected as much as in the sweetgum case. Activation energies and the influence of particle si 2e showed behavior similar to that in tne hydrolysis of prehydrolyzed sweetgum wood , aa aid the tent ot * * hydrolysis wit * i * HCl at 70 C. ° ° * In the presence of lithium , zinc ana calcium pure cellulose and cellulose in botn hardwoods and softwoods can be hydrolyzed to glucose in good yield at hydrochloric acid concentrations as low as 24 % , although in the absence of the salts cellulose is resistant to hydrolysis at these acid concentrations. At 37% HC1, still below the critical concentration for cellulose hydrolysis without salts, the hydrolysis with salts requires less salt and lower temperatures than at 24 %. The most rapid rates of hydrolysis were obtained with zinc , but since the influence of the salts on extent of hydrolysis corresponded to their equivalent weights lithium proved to be most effective on a weight basis. The presence of lignin in wood retards the rates of hydrolysis compared to pure cellulose. Tnis retarding effect was much greater tor zinc than tor the others, and much more apparent for the hardwood , sweetgum than for tne softwood , southern pine. REFERENCES 1. °- ° - - 2. . - BEARDSMORE, A.J • r The production of chemical and fermentation feedstocks from lignocellulosic material. Proc. Roya - Society London , 77 83 November (1983). ° ° PEREIRA , H., PITTMAN , J.L• 9 STROUSE, B.A • 9 AND SCARINGELLI , F.P. The hydrolysis ot cellulose with super 9 concentrated hydrochloric acid. Biotechnology and Bioengineering Symposium 13: 17 25 (1983). 1 . GOLDSTEIN , I.S • 3. - bAYAT MAKOOI, F. AND GOLDSTEIN , I.S. Hydrolysis of cellulose with hydrochloric ^cid enhanced by cations, in Proc. Cellucon 84 C » Ilulose Chemistry and Technology. Chichester : Ellis Horwood , ( 1905). - Flotation ( 2 , 3 , 1 ) The flotation experiments were performed on model dispersions of in* particles in sodium stearate solutions. To these dispersions the THE COLLOID CHEMISTRY OF WASTE PAPER DEINKING chemicals present in Anders Larsson , Per Stenius , Lars Odberg Institute for Surface Chemistry Box 5607 S il 4 86 Stockholm Sweden » deinking plant were added . Flotation was " hen performed in a Hallimond tube ( a simple glass device normally used for mineral floatability studies ). Afte flotation the remaining ink particle concentra tion was determined . In one series the size distribution of the remaining ink particles was also determined. A flotation kinetics experiment showed that the ink particle removal followed pseudo first order kinetics to a good approximation. It was also found that the first order rate constant increased exp nentially with the particle dia meter . This behaviour was later confirmed in laboratory scale deinking experiments with a waste paper pulp. With calcium stearate as collector , tne floatability was improved with increasing calcium and steara re concent rat ions. There was also a clear correlation between floatability and zeta potential of the ink particles , such that the flotation rate was highest when the zeta potential had been decreased from 85 mV to about 40 mV by addition of at least 2 mmole/1 Ca 4. The floatability also improved with increasing concentration of sodium chloride but decreased with increasing concentrations of nonionic surfactants or kraft lignin. - - INTRODUCTION In the process of waste paper deinking colloid chemistry plays an essential role in a number of disrinct steps. The most important of these are: i ) the detachment of ink from - - the fibres , ii ) the dispersion of the ink into small particles , iii ) the redeposition - of ink particles onto fibres , iv ) the elimina tion of the ink particles from the pulp suspen s on by flotation or by washing and v ) the - clarification of recycled process water. In the present investigation we have studied steps no. ii ) v ) under conditions typical for a flotation deinking plant. The objective of the work has been to elucidate the mechanisms of the processes involved anr* to determine the influence of different factors on the performance of each step. - Dispersion ( 1 ) - - - ^ The dispersion of the ink was studied in laboratory scale deinking experiments. Old newspapers were slushed with deinking chemicals and the size distribution of the ink particles in the pulp was determined with a computerized imago analyser. In one series of experiments newspapers with different printing inks were slushed . The results then showed that those offset inks which cause problems in deinking after aging , disperse into smaller particles than other inks. In another series the influence of different chemical factors on the dispersion was studied. The most striking effect here was that calcium stearate , which is usually added as collector for the flotation , increases the mean diameter of the ink particles consider ably when present in the pulper. A probable explanation for the phenomenon is that the calcium stearate induces agglomeration of the ink particles simultaneously with the dispersion. « eCIPITAT*0 *CALCIUM f IO* PANTICLtt - Figure L Suggested collector mechanism of calcium stearate 1985 Wood and Pulping Chemistry Symposium 3 Examination of t h e ink dispersions by l i g h t and s c a n n i n g electron microscopy revealed that the calcium s t e a r a t e w a s precipitated as a layer of discrete particles on the surface of the ink particles. This observation and t h e floatability results above form the basis for the collector mechanism of calcium s t e a r a t e suggested in figure 1 . In the pulper t h e ink particles obtain a high n e g a t i v e z e t a potential d u e t o adsorption of soaps and ionization of acidic groups in the ink surface. The n e q a t i v e potential promotes the detachment of the ink and provides stability t o the dispersion. H o w e v e r it gives rise t o a repulsion between the ink particles and t h e negatively c h a r g e d air bubbles and t h u s prevents flotation. When calcium s o a p is precipitated it forms a layer of small particles around t h e ink particles and t h u s give them t h e surface properties of t h e calcium soap. In the presence of a n excess of calcium t h e y then become hydrophobic and obtain a low z e t a potential s o that t h e y can easily attach t o t h e a i r bubbles. T h e calcium s o a p also induces agglomeration of the ink particles . T h i s increases their effective diameter which is beneficial for the flotation r a t e. Hedeposition ( 4 ) T o study t h e deposition of ink particles o n t o fibres , model ink dispersions were mixed with the long fibre fraction of a thermomechani cal pulp. T h e y were then w a s h e d u n d e r stirring in a specially designed filter cell t o remove all non - deposited ink p a r t i c l e s from the pulp. T i e a m o u n t of deposited ink was then ^ termined by measuring t ’ e reflectance of t h e p u l p. The results show that under certain conditions extensive d e p o s i t i o n o f ink particles m a y occur. However , the deposition can be efficiently p r e v e n t e d by nonionic surfactants normally added as dispersants. Waterglass h a s a certain effort in preventing deposition , which can , ted montmori 1Ionite c l a y and a high molecular w e i g h t polyacrylamide. With the cationic/anionic polymer system high amounts of cationic polymer had t o be added in order t o neutralize the dissolved anionic material in the w a t e r. This made t h e s y s t e m considerably less cost effective t h a n t h e t w o other s y s t e m s , which both performed well a t reasonable addition levels. CONCLUSIONS In t h e process of flotation deinking t h e demands o n colloidal s t a b i l i t y a r e somewhat contradictory. D u r i n q the first part of t h e process a h i g h colloidal s t a b i l i t y i s n e c e s s a r y for the detachment o f the ink and i t s dispersion into particles of suitable s i z e. A certain stability i s a l s o needed t h r o u g h o u t t h e process t o p r e v e n t the detached ink particles from redepositing o n t o the fibres. T h e s t a b i l i t y m u s t however be lowered before the pulp r e a c h e s t h e flotation cells in order t o facilitate a t t a c h m e n t of the ink particles t o t h e a i r bubbles. T h e w a s h i n g process appears t o b e simpler from t h e colloid c h e m i s t r y point of v i e w. Here a h i g h colloidal stability should be maintained t h r o u g h o u t t h e actual d e i n k i n g o p e r a t i o n s t o facilitate detachment and disper s i o n o f t h e ink t o small particles and preventing redeposition. H o w e v e r , pollution laws in m o s t countries r e q u i r e that the , stability m u s t be broken t o make t h e suspended material flocculate. REFERENCES 1. L A R S S O N, A., S T E N I U S , P., ODBERG, L • r Svensk P a p p e r s t i d n. 8 7 ( 18 ):R 165 ( 1 ^ 8 4 ) 2. LARS O N, A., STENIUS, P • r 6 DBERG ; L., Svensk P a p p e r s t i d n. 8 7 ( 1 8 ):R 1 5 8 ( 1984 ) 3. LARSSON, A • STENIUS, P., S T R O M. G • » Wochenbl . fur P a p i e r f a h. 110( 14 ):502 ( 19 H 2 ) 4. LARSSON, A • STENIUS, P • t ODBERG , L., Svensk P a p p e r s t i d n. 8 8 ( 3 ):R 2 ( 1985 ) 5. BOKSTROM , J., L A R S S O N , A., ODBERG , L• , R e s. Disclosure ( 2 3 7 ):5 ( 1984 ) bo related t o its ability t o precipitate alumi n a t e ions p r e s e n t in the pulp. Clarification of p r o c e s s w a t e r ( 5 ) Process water from t h e pulper loop of a flotation deinking mill was clarified by micro flotation in laboratory and pilot scale T h r e e iocculation s y s t e m s were tested: i a conven , iona 1 system consisting of a low molecular *n cationic polymer and a high molecular w e i g h t anionic polymer , ii ) a w a t e r soluble weiq - r honol formaldehyde r e s i n and high molecular weight poly ( oxyethylene ) and i i i ) alkali activa - 4 - process w a t e r be recirculated . T h e recirculation t h e n involves a clarif 1 c a t ion process and h e r e t h e colloidal - # # G a s c h r o m a t o g r a p h y -mass s p e c t r o s c o p y ( GCMS ) analysis o f the mixture o f aromatic CHEMICAL CHARACTERIZATI ON O F KRAFT LIGN 7 KRAFT LIGNIN PRODUCTS . . F. G r i g g s, J A. V e n i c a *B *‘ AND Gratzl , C- L. C h e n , and N o r t h Carolina State University , D e p a r t m e n t of Wood and P a p e r Science, Box 8005, Raleigh , N o r t h Carolina 27695- 8005 carboxylic acids ( methyl e s t e r s ) formed following p e r m a n g a n a t e oxidation o f kraft lignin fractions s h o w e d significant differences in the yields of t h e major oxidation products between h i g h and low molecular w e i g h t fractions which may indicate a n o n r a n d o m lignin formation in w o o d y p l a n t s. ‘Present Address: U n i o n C a m p C o r p o r a t i o n, P.O. Box 3301 , Princeton , New J e r s e y 0 8 5 4 0 ABSTRACT Lignins isolated from pine kraft black liquor were fractionated and purified by ultrafiltratio n. T h e fractions were characterized using gel permeation chromatography and C - NMR spectroscopy in combination with chemical methods including GCM S analysis of the mixture of aromatic carboxylic acids obtained by p e r m a n g a n a t e ^ oxidation of methylated l i g n i n s and lignin p r o d u c t s. Gel permeation chromatography of the u n f r a c t i o n a t e d kraft lignin revealed that ap : oximately 5 0% was less than 5, 0 0 0 and a b o u t 3 0% w a s less than 1 ,2 0 0 M . T h e e t h e r w s o l u b l e fraction possesses an average molecular w e i g h t of 6 0 0. Methoxyl c o n t e n t ( % ) of kraft l i g n i n fractions was found t o decrease with d e c r e a s i n g molecular weight. Phenolic hydroxyl c o n t e n t was found t o increase while aliphatic hydroxyl g r o u p s decreased with decreasing kraft lignin molecular w e i g h t. Mw ' T h e ionization Ac absorption curves of kraft lignin and kraft lignin fractions indicate vast differences in the t y p e s and quantities of chromophoric s t r u c t u r e s between f ractions. Results indicate that the relative , 0/ -s t i lbene s t r u c t u r e s and p h e n o l i c a m o u n t of hydroxyl content increases with decreasing molecular w e i g h t. Signal a s s i g n m e n t s in the * * C - NMR s p e c t r a were made on the basis of substituent shifts observed in model c o m p o u n d s, Kraft lignin fractions were found by 3 - C - NMR t o contain xylan fragments apparently covalently bonded to the 1 ignin. Unsaturated vinyl structures were found t o be present in all lignin fractions ; however, based on some k e y * 3 C s i g n a l s , it is believed that the m a j o r i t y of £, 0/ - stilbene structures are present in the low molecular weight fractions. ^ 1985 Wood and Pulpinq C h e m i s t r y S y m p o s i u m T h e chemical characterizati on was extended t o kraft lignin preparations obtained b y hydroxymethyla tion , sulfomethylati on a n d oxidative sulfonation. A n u m b e r of hydroxymethylat ed , sulfomethylate d and oxidatively sulfonated lignin model c o m p o u n d s were synthesized t o s t u d y t h e chemical shifts in 1 3 -C - NMR as related t o the lignin . preparations T h e use of * 3C-enriched formaldehyde in hydroxymethylat ed and su 1 fomethyla ted kraft lignin p r e p a r a t i o n s assisted in monitoring structural c h a n g e s in various s i t e s of the lignin polymer by clearly defined s h i f t s d u e t o s i g n a l enhancement i n t h e i 3 C -NMR s p e c t r a. Alka 1 ine- formaldehyde treatment for hydroxymethyla tion of unetherified guaiacyl moities in kraft lignin was found t o be most effective at 55°C introducing approximately 0.42 -CH 2 OH p e r OCH 3. 1 * C - NMR s p e c t r o s c o p y showed that hydroxymethylat ion occurred mostly at C- 5 in unetherified g u a i a c y l moieties with little or no modification o f alkyl side cha ins. GC- M S analysis of p e r m a n g a n a t e oxidation p r o d u c t s indicates an eightfold increase in isohemipinic acid , o r i g i n a t i n g from C- 5 hydroxymethyla ted unetherified guaiacyl moieties , with a corresponding decrease in veratic acid. Alkaline - formaldehyde t r e a t m e n t a t high t e m p e r a t u r e ( 1 5 0°C ) did not result in a m significant degree of hydroxymethyla tion of either unetherified guaiacyl moieties or alkyl side chains a s evidenced by 1 -* C - NMR and hydroxyl group analysis . l 3C - NMR s p e c t r o s c o p y revealed that the lignin p r o d u c t did , however , contain many structures characteristic o f alkaline condensation reactions. 5 Su 1 fomethy 1 ation of softwood kraft lignins using a two step procedure , hydroxymethyl ation at 55°C followed by sulfonation at 150°C , was found to be much more selective resulting in higher product yields than the conventional one step sulfomethylat ion procedure , 13 C NMR analysis of 13C formaldehyde enriched two step - - - - - su 1 fomethylated lignin revealed almost quantitative (92% ) sulfonation of hydroxymethyl groups attached to C 5 of unetherified guaiacyl moieties. - - 13 C NMR analysis of lignins subjected to one step sulfomethylat ion showed major modification to alkyl side chains presumably - due to Tollens and Prins reactions at the high temperature in addition to formation of aromatic and aliphatic carboxylic acids, origin and mechanism of formation of the The carboxyl structures is not known. Oxidative sulfonation of softwood ( pine ) kraft lignins resulted in complete solubilizatio n of kraft lignin in water at both alkaline and acidic pH. The degree of sulfonation was shown to increase with decreasing molecular weight. Approximately 0.07 0.10 equivalents of sulfonic acid groups and 0.9 1.4 equivalents of oxygen per C 9 unit - - - were introduced. The increase in oxygen content reflects the introduction of oxygen containing groups such as carboxylic acids as a result of au:oxidation. Gel permeation - chromatograph y of oxidatively sulfonated lignins reveals a marginal increase in overall molecular weight apparently due to competition between oxidative degradation ( fragmentation ), oxidative coupling and condensation reactions. - The 13C NMR spectra of kraft lignin revealed major structural chances due to introduction of sulfonic acid groups predominantly at C 5 position of unetherified guaiacyl moieties and formation of aliphatic carboxylic acid groups. Results from model compound experiments and GC MS analysis of - - permanganate oxidation products support the involvement of radical processes in both sulfonation and oxidation , with sulfite radicals in some cases being the sulfonating species * 6 o r m e c h a n i c a l l y d i v i d i n g the c h i p s s i g n i f i c a n t l y i n c r e a s e d t h e e x t e n t o f h y d r o l y s i s. St earn THE FRENCH EXPLODED WOOD PROJECT t e m p e r a t u r e) (or pressure wer e v a r i e d from 2 0 b a r s t o 50 bars and t i m e From 10 s e c t o 240 s e c. Both p a r a m e t e r s e q u a l > affected t h e s e v e r i t y o f t h e t r e a t m e n t s o * hat t h e s a m e result could h a v e b e e n obtained either a t low p r e s s u r e a n d long t i n u* o r t h e D o m i n i q u e LACHENAL Pierre MONZIE CfNTRL T E C H N I Q U E DU PAPIER B.P. 7110 38020 GRENOBLE CEDEX FRANCL c o n t r a r y. Extended Abstract o f the ceI IuI o s i c r e s i u u e and t h e s t r u c t u r e of the V A R I O U S p r o d u c t s varied c o n t i n u o u s l y w i t h t h e s e v e r i t y ot the t r e a t m e n t . Quality St earn exp I osion first was i ntroduced m e than 50 y e a r s a g o b y MASON , U s i n g s t e a m a * about 280°C , the MASON Process e x p l o s i v e l y d t ibrated wood w a s t e t o g i v e a brown h y d r o l y z e d p u l p s u i t e d t o t h e manufacture o f p a r t i c u l e board. In r e c e n t y e a r s , t h e i n t r i n s i c s i m p I i c 11 y o f the p r o c e s s has attracted the a t t e n t i o n oi a number o f workers t o e x a m i n e m e a n s o f employing t h e s a m e p r i n c i p l e for m a n y o t h e r < a p p I i c a t i o n s. The possibiIity of producing dissoIving p u l p f r o m wood b y t h i s method w a s i n v e s t i g a t e d. The f i n d the p r o p e r conditions w h i c h would lead t o a p u r e cellulosic residue o f a c c e p t a b l e q u a l i t y and a t t h e s a m e t i m e t o a h i g h value l i g n i n b y p r o d u c t . purpose was to - Five project the laboratories w e r e involved i n t h i s order t o define the effect o f in processing parameters (mainly chip quality , and time ) the h y d r o l y s i s o f hemicellulose , cellulose and A 501 i g n i n. e x p l o s i o n steam capacity r e a c t o r w a s built p r o c e s s . The CTP quite w a s similar to \ at I 0TECH e x p l o s i o n p r o c e s s. The maximum the d j e r a t i n g p r e s s u r e w a s 6 0 bars. Aspen c h i p s w e r e s u p p l i e d b y a mechanical p u l p m i l l located close t o Grenoble. Analysis o f t h e effect of t h e p a r a m e t e r s w a s p e r f o r m e d u s i n g a seond order , central c o m p o s i t e d e s i g n. The q u a d r a t • c r e s p o n s e surfaces w e r e calculated. E x p l o d e d wood s a m p l e s w e r e extracted w i t h d i s t i l l e d at room temperature for ana Iysis of water hemiceI IuIose , sugar and low molecular weight p h e n o I s. Lignin was extracted by a dioxane water ( 82: 18 , V : V ) mixture from the water extracted ami analyzed for functionality and produc t The quality of the cel lulosic mo lei uIur weight residue was assessed by its degree of polymer i tempcrature on - - . zat. ion and l i g n i n content . Heat 1 iictor mean transfer a p p a r e d t o be a limiting wood chips ( 3.5 m m chip Reducing thickness w h e n u s i n g industrial thickness). - 1985 wood and Pulping Chemistry Symposium - p H o f t h e water extract decreased f r o n 6 to 3 5 when t h e s e v e r i t y o f the t r e a t m e n t i n c r e a s e d . a n d p.h y d r o x y b e n z o i c a c i d w a s found t o b e r e s p o n s i b l e for t h e p H decrease. Depolymer c a t i o n o f hemiceI IuIose w a s correlated w i t h t h e t r e a t m e n t c o n d i t i o n s b GPC a n a l y s i s of the w a t e r e x t r a c t . 1 he liberation o f acetic \ D e p o l y m e r i z a t i o n o f cellulose a n d lignin place simultaneously was it that so •o k »t possible to get a r e s i d ue cel lulosic »•i DP h i g h e r than 200 c o n t a i n i n g less t h a n IQ'X I i g n i n. As a n e x a m p l e , w h e n t h e s t e a m e x p l o s i o n w a s p r o c e s s e d a t 4 0 b a r s for 120se c , t h e DP o f t h e cellulosic r e s i d u e w a s 150 i gn i n and i t s . A DP around content was 8 6 0 0 w a s o b t a i n e d after h y d r o l y s i s a t 30 b a r s for 9 0 s e c. Then , t he content was gnin 13 %. Elimination o f hemiceI IuIose occured almost c o m p l e t e l y i n both c a s e s. Other o r g a n i c solvents and caustic soda w e r e tested i n order I i gn i n t o r e p l a c e dioxane w a t e r for T * - e x t r a c t i o n w i t h o u t s u c c e s s. Characterisal i o n of the i gn i n fraction 13C NMR revealed that the c l e a v a g e o f / 0 4 £ by ether linkages w a s c l o s e l y related t o t h e y i e l d o f extractable l i g n i n a n d t o t h e treatment s e v e r i t y. A c o n t i n u o u s decrease from a n e s t i m a t e d value o f 0. (> p e r C 9 u n i t i n MWL t o 0.1 after s t e a m h y d r o l y s i s a t 45 b a r s for l 80sec w a s observed. Simu 11 aneousIyi t h e OH p h e n o l i c groups increased from 0.2 (p e r Cg u n i t ) t o a m a x i m u m o f 0.7 alter s t e a m h y d r o l y s i s a t 35 bars for 150 s e c ) a n if then decreased , i n d i c a t i n g that for t h e m o s t s e v e r e con d 11 i o n s either condensation occured o r that s m a l l l i g n i n fragments ol h i g h OH p h e n o l i c c o n t e n t w e r e lost t o a g r e a t e x t e n t w i t h t h e w a t e r e x t r a c t . Reduction of the n u m b e r of a l i p h a t i c OH g r o u p s w a s a l s o observed. St i I bene s t r u c t u r e s and c a r b o n s I g r o u p s w e r e detected. DemethyI a t i o n did n o t a p p e a r t o b e e x t e n s i v e ( I r o m 1.4 - per C9 u n i t in MWL t o o m i m i n u m o f 1.1 ) g i v i n g 7 rise t o the format ion of some catech ol g r o u p s. The number a v e r a g e molecu lar weight of the lignin fracti on varied from 1000 t o 2000 g/moIe withou t a n y direct correl ation w i t h the p r o c e s s condit ions , The yield of aldehy des libera ted u p o n alkali ne oxydati on w a s m i n i m a for the most drasti c condit ions ndieat ing a probabl e condens ation of phenoli c rings. Modifi ed ( sulfon ated and oxidiz ed ) s t e a m explosi on ignins , recove red after p r o c e s s i n g 40 bars for 80 sec , at and sants appear to w e r e tested a s disper s e q u e s t r a n t s. be v e r y - T he result s d i d not p r o m i s i n g. Other a p p l i c a t i o n s should be contemp lated. Chemic ally modify ing the i gn i n pr i or o r during s t e a m hydrol ysis s e e m s t o be the only chance of gettin g a p u r e cel lulosi c residu e with accept able DP. to t • i < < • i . v *' i • »l t# l I J* * r* »t ’# I I <**» * * J - •. • » ' '1 i 1 *i 1 M l* t 8 , I 4 I CONCLUSION THE INFLUENCE OF NaOH AND Na 2 SQ 3 ON THE QUALITY OF I t i s concluded that the usage of NaOH is essential i n CHEMITHERMOMECHANICAL PULPS OF HARDWOODS making good quality chemithermonechanical pulps from KEN LAW , MARCEL LAPOINTE AND JACQUES L . VALADE Centre de recherche en pStes et papiers U n i v e r s i t y du Quebec 3 Trois Rivi $ res C. P . 500 , Trois - Rivi £ res , Quebec G9 A 5 H7 . The Na S03 helped maintain the brightness of the pulps and reduce the refining energy . hardwoods - Table ABSTRACT Chemithermomechanical pulping of 4 hardwoods ( white 5 0 0 5 5 7.24 5.04 6.0 4.96 C. S F , mL 310 131 424 138 Brightness , % 50 42 61 49 Tear index 1.80 7.09 1.81 7.76 . 07 3.72 0.92 4.22 .. . Pretreatment , Refining, Betula , Populus , Acer 0 MJ / kg had significant effect upon the pulp quality , whereas the Na 2 S03 was of limited importance from grey birch 5 % Spec , energy The results indicated that the NaOH _ '_ d 0 Na 2 S 03 . using NaOH and Na 2 S03 in the treatment of chips prior to pressurized refining, TMP and CTMP pro NaOH , birch , grey birch , aspen and red maple ) was carried out KEYWORDS : 2 . mN.rr.’ / g INTRODUCTION This paper deals with the pretreatment of hardwood chips B . le jth, km * with NaOH and Na 2 S 03 in the production of chemithermomechan ical pulps ( CTMP ) Pulping trials were carried out with a . Sunds Defibrator 300 CD refiner . The chemical pretreatment of chips was performed b „, means of the PREX impregnator which is integrated in the digester . The following is an account of our experiences in pro white birch , grey birch , ducing CTMP from 4 hardwoods : aspen and red maple . Table 2 . CRMP produced from red mapV NaOH , % 3 5 5 5 5 Na 2 Sr / 3 , % 0 0 3 5 6 . . , ml 163 248 190 179 206 Brightness , % 37 34 34 4, Tear index 2.31 2.45 2.78 3.33 2.86 1.70 1.96 3.34 3.25 2.99 C S. RESULTS AND DISCUSSION . EFFECT OF NaOH 43 mN m 2 / g The NaOH had remarkable influence on a l l pulp properties . In fact the strength characteristics of the pulps B . length, km studied . were improved with an increase in the level of NaOH addition Meanwhile the bulk of the handsheets and the brightness of the pulps decreased as the usage of NaOH augmented . WHITE BIRCH CTMP 9 7 x pretreated with 5 X NaOH gave excellent properties , U LEGEND _ ° NoOH z o> 5 nomically j u s t i f i e d and at higher levels of NaOH treatment 3 < uj E UJ I t was observed that the pulps made from the chips O Further increases in NaOH above this level did not seem to be eco - the improvement in pulp quality was marginal ( Figs and Tables 1 - 3 ) . e 1 . 1, 2 X UJ § \* EFFECT OF Na 2 S03 K CO Concerning the influence of Na 2 S03 , l i t t l e improvement a: in the pulp properties was noted , except for the brightness CD which increased with an increase i n the level of Na 2 S03 when the usage of NaOH was also relatively high , 5 X or more I t was , hence , necessary to add Na 2 S 03 to the liquor to maintain a certain level of brightness . I t was also noted that the specific energy consumption was generally decreased as the application of chemicals This could imply that the increased ( Fig 3 , Table 1 ) softening of lignin by the action of Na 2 S 03 accompanied by the swelling of fiber walls caused by NaOH , facilitated fiber separation during refining The chemical energy was traded for thermal energy with a concomittant improvement In the properties of the pulps . . • TMP 4 ~ E 2 o ^ o E. 0 * - 1 < h UJ O a z CD UJ F i g. 1 O o 60= —6o—=o5 a o o—o O O O o £ 6 X . . 0 2% D 7 % 0 3 % A 10 % 4 2 0 0 O o o o O O r\ o 8 10 03 l % 12 1 x 2 4 6 N a 2S . E f f e c t o f NaOH and N a S 0 o n the strength properties of .? j white b i r c h CTMP. . 1985 Wood and Pulping Chemistry Symposium 9 Table 3 . R E D MAPLE CTMP PRODUCED FROM FRESH CHIPS NaOH , % Na SO 3 * X * SPECIFIC ENERGY , MJ / kg FREENESS , ml BULK , cm5 / g BRIGHTNESS , X OPACITY , X BURST INDEX , kPa - m* / g TEAR INDEX , mN ‘ mJ / g BREAKING LENGTH , km ASPEN 7 X UJ 2 ? I 4 0' O'"' 02 % 2 CL e 0 7 C7< -\2 8 2; 7 5 5 % NaOH 10 NaOH * 2% 5% . o 5 TMP UJ JL 0 5 10 Na 2 S 03 # 15 % . 2 . E f f e c t o f NaOH and Na , S 0 20 ^ on t e strength properties of asp e n CTMP . ^ a: 6 TMP UJ UJ I O UJ 02 % £O 3 Fig o ~ 5 % NaOH “5 < H GO o TMP je GO o TMP E CL in 4 0 2 10 8 6 4 No 2 SO , °/o ^ F i g . 3 . E f f e c t o f NaOH and N a ? S 0 specific refining energy . ^ .2 on t h e purity c:’ a vl by C 3 2..r. sp~ rr.odel compounds was checkec roscopy. • Si 2 ; MS . . * ctr& were measured in CDC1, 3 olutic :.s on a ariar XL 200 spectrometer at jperatmg :recuorcy of 39.7 Mbz for Si 29 nucle *. INEPT Technique was employed as described in detail elsewhere ( 3). The FIDs were recorded with proton decoupling, acquisition time was 1 s a.. d delay between the successive pulse trails was 5 3. " vpically , 128 scans were accu mulated in model compound experiments ai.d 3000 6000 scans were required for lignins. Assign ment of Si 29 NMR spectral lines in model com pound spectra was facilitated by the SPINEPTR technique (4)* The model compound experiments showed good proportionality between the signal intensity and the molar ratio cf the corres ponding Me -,SiO groups. +. - - STUDY OF LIG ?!TW STRICTURE BY SILICON " ~ NMR SPECTFOSCCF: 'CA ROIZRT BRE2NY 1 , JAN SCHRAML2, MAGDALENA KVl 2 LO » n , JAN ZFLENY2, VACLAV CHVALOVSlrf2 - ' 1 INSTITUTE OE CHEMISTRY , SLOVAK ACADEMY OP SCO NCES, CC 842 38 BRATISLAVA, CZECHOSLOVAKIA 2I ;.YT:TUTE OF CHEMICAL PROCESS FUNDAMENTALS, CZr CH0SLOVAK ACADEMY OF SCIENCES, CS 165 02 PR.,CUE, CZECHOSLOVAKIA - - - - . - . - - ABSTRACT Jiliccn 29 NKR spectra cf trime ^ hylsilyla te pruce dioxane ligrin as well as softwood kraft lignin ar.d its derivatives are reported The observed resonances are interpreted with the ai :. of data obtained in model compound ex periments The utility of the method lor ana lysis of lignins and lignin derivatives is - ’ - . discussed - - - - - - - RESULTS 4 In our set of trimethylsilylated ligrin model compounds, the cTvalues in Di 29 NMR spectra were influenced primarily by electron density at oxygen atom of Me ->SiO groupa and de creased in order COOSiMe - > aryl CEiMe > alkyl OSiMe, Pronounced steric influence was obser ved only in aryl OSiMe, groups derived from guaiacyl moieties substituted in position 5. The spectrum of trimethylsilylated spruce dioxane lignin (Fig.1.) shows two groups of sigrals corresponding to aryl CSiMe , ( < ^ 20 2 1 ) and alkyl OSiMe -> ( " 3. SCHRAML, ' . Routine ise of INEPT techni for measi emert of £ 'Si NMR spectra of que tri methvlsil; 1 derivatives. Coll Cor. n 4 i : 3402 3406 ( 19837; Czech Chem SCHRAML, . INEPT With selective decoupling of proto:.: used for polarization transfer routine assignment technique for 29Si NMR spectra o: trimethylsilvlated products. J Man Resonance 59: 515 517 ( 1984 ) , ' dures at reasonable demands on measuring time and sample amount ( 100 mg) Spectra afford , at least , 3emiquantitative information on dis tr Vjtion of OH and COOK groups and reflect also the structure of arylalkyl units in lignin macromolecule. ~ ; REFERENCES 1 SCHRAML, J , PETRXKOVA , E., FI HAR , 0., HIRSCH, J , CHVALOVSKY , V Si Chemical . 4 - - - - , - . - - 1 ) Development o f H ? ar idle c o n d 111 o n s De 1 l q n 1 f 1 cat 1 o n u s i n g h y d r o g e n p e r o x i d e a n d o x y g e n under a c i d i c c o n d i t i o n s the PO treatment s - Hans Ulrich Suss , Horst Kruger Degussa AG D 6 4 3 0 Hanau , W. Germany - - 02/0 - del q m ficat ion under At constant t e m p e r a t u i f* a n d o x y g e n pressure , the rate of delignification plotted against t h e pH value s h o w s a steep d e c r e a s e leaving strong alkaline c o n d i t i o n s and c o m i n g c l o s e t o neutral 1 ty . - While d e 11 gn I f I ca t I o n rates o f m ;* re than SO % a r e o b t a i n a b l e under strong alkaline con d i t i o n s , o n l y p o o r effects can b e achieved at lower pH values. - - ABSTRACT - At a pH level below 4 , hydrogen p e r o x i d e reacts as a n e l e c t r o p h i l i c agent a n d cleaves t h e lignin molecule. In the presence of oxygen , the reaction b e c o m e s very efficient . At pH 2 w i t h hydrogen p e r o x i d e and oxygen , the k a p p a n u m b e r s of sulfite p u l p s are reduced to 3 0 % of t h e i r initial levels. W i t h MgO , a pH of only 9 to 9 . 3 is obtained. Consequently , under m i id c o n d i t i o n s only p o o r results a r e the result o f oxygen treatment i n the p r e s e n c e of m a g n e s i u m o x i d e. W i t h neutral or acidic condiIrons a delignifi c a t i o n w i t h o x y g e n i s nearly i m p o s s i b l e. . /. - There i s only a p o o r effect u n d e r very a c i d i c CONDITIONS. Most 1 y , it i s the result o f a w a s h i n g p r o c e d u r e during the treatment , a n d o f a c i d i c h y d r o l y s i s. - The best and most efficient c h l o r i n e free deligni fication p r o c e s s for sulfite pulps i s a hydrogen p e r o x i d e s u p p o r t e d o x y g e n d e 1 IGNIFICATLON i n the p r e s e n c e of s o d i u m h y d r o x i d e ( 1 ). Nevertheless , t h i s method will not b e i n the focus o f this p r e s e n t a t i o n , t h e most recent d e v e l o p m e n t i n pulp - the d e 1 ignification with hydrogen p e r o x i d i n t h e p r e s e n c e of oxygen under acidic conditions. We use the initials P0 for p e r o x i d e , o x y g e n and sour , or acidic , c o n d i t i o n s. The bleaching is f p r o c e d u r e was d e v e l o p e d \ in 1984 o n a laboratory scale b y Degussa AG und PWA Waldhof. Pilot plant trials started at W a l d h o f i n F e b r u a r y t h i s year. After an initial p h a s e w i t h one ton of p u l p per hour , temporarily the full c a p a c i t y of the older p r o d u c t i o n line w i t h 100 tons of s p r u c e per day was delignified . The a i m of t h i s paper i s to d e s c r i b e the Hydrogen p e r o x i d e behaves a b i t d i f f e r e n t l y . Similar to oxygen , there i s a steep decrease of the delignification rate if t h e pH value - d r o p s from alkaline to neutral c o n d i t i o n s. - At lower pH values , the d e l i g n i f i c a t i o n rate r i s e s a g a i n. The lower the pH value , the higher i s t h e d e c r e a s e o f lignin content i n pulps. The first figure i l l u s t r a t e s the effect of pH value o n delignification for oxygen and hydrogen p e r o x i d e . - - Delignification % Too Aae 8o 25 3o 2o 6o 15 - the reaction parameters , . d e v e l o p m e n t of the procedure 4o 1o 2o the mechanism of d e 1 lgniflcatlon , - the process 's advantages and d r a w b a c k s , - results of the pilot plant trials. 5 P 0 1 2 3 4 5 6 7 8 9 1o 11 12 13 pH Figure 1. Delignification o f sulfite p u l p w i t h o x y g e n or hydrogen p e r o x i d e a s a function of the pH value . ( 20 °«» cons. 9 3° C , 1 h , 1 $ H , 0 . 3 M P a Q ,> - 202 1985 w od and Pulping Chemistry Symposium ° 13 This effec t w a s r e p o r t e d i n liter ature ( 2) sever al y e a r s ago. The mecha nism of d e 11 gn 1 fica 11 on i s a n e l e c t r o p h i l i c attac k of t h e h y d r o x o n i u m t i o n. To o b t a i n a s t e e p decre ase i n ligni n c o n tent , it shoul d b e lower t h a n A . - ion on t h e a r o m a t i c nucle i . Some paten ts ( 3 ) c l a i m The oxyge n p r e s s u r e s p e c i a l effec ts for hydro gen p e r o x i d e delig ni f i c a t i o n under a c i d i c c o n d i t i o n s , for examp le , prese nce of oxyge n - a s p e c i f i c effec t of h e a v y metal i o n s o n t h e d e 1 LGNI FICA TION p r o c e s s i s claim ed . Anoth er paten t o f less i m p o r t a n c e . The i s obvio usly n e c e s s a r y to is get a b e t t e r effec t t h a n w i t h h y d r o g e n p e r o x i d e alone . There i s a s y n e r g i s t i c effec t if b o t h c h e m i c a l s are c o m b i n e d . As figur e 3 illus trate s, d e s c r i b e s the a p p l i c a t i o n of chela ting agent s to reduc e visco sity losse s , and claim s n o effec t of h e a v y metal s o n the d e 1 LGNI FICA TLON p r o c e s s. rate worse ns. In all of these a p p l i c a t i o n cases , hydro W i t h o u t p r e s s u r e , but i n the p r e s e n c e o f a i r, resul ts a r e sligh tly b e t t e r t h a n w i t h n i t r o g . en - gen per o x i d e react s w i t h s i g n i f i c a n t l y lower deligni ficat ion inten sity c o m p a r e d w i t h stro ng alkal ine - c o n d i t i o n s. If the a p p l i c a t i o n of h y d r o g e n p e r o x i d e a n d oxyge n c o m b i n e d , the curve for the d e 1 LGNI FICA TLON rate i n the alkal ine area i s very close to is those for oxyge n a n d hydro gen p e r o x i d e a s singl - e com p o u n d s. Acidi c c o n d i t i o n s resul t i n a signi fican t i n c r e a s e o f the d e 1 IGNI FICA TLON rate. Figur e 2 illus trate s t h i s effec t. - in t h e p r e s e n c e of n i t r o g e n , the d e 1 LGNI FICA TLON On the other h a n d , incre asing the oxyge n p r e s s u r e from 0. 2 MPa to 0 . 7 MPa d o e s not i m p r o v e r e s u l t s. The s y n e r g i s t i c effec t b e c o m e s o b v i o u s if the pulp i s r e a c t e d w i t h hydro gen p e r o x i d e first , a n d o x y g e n i s a d d e d only after nearl y total c o n s u m p t i o n o f the p e r o x i d e. The r e sulting de ll GNIF ICAT LON rate i s poor c o m p a r e d w i t h the - c o m b i n e d a d d i t i o n o f b o t h c h e m i c a l s. In fact , at low p H value s d e 1 LGNI FICA TLON w i t h 2 2 2 * S near]y as effic ient a s i n the p r e s e n c e of alkal i. A 5 0 < decre ase of ligni n conte nt i s a c h i e v e d , a s figur e 2 s h o w s . H ^^ A# 8o 25 6o Delignification % Delignification % Too A 1oo * 3o without pressure 2o air 15 3o 4o 1o 8o . o 3 MPa pressure 25 2o 2o 6o 15 4a 5 11 / f 1o 2o 5 Figur e 3. 1 2 3 4 5 6 7 0 9 1c 11 12 13 Figur e 2. pH C o m p a r i s o n o f t h e delig nific a rates achie ved with hydro gen » o n roxide, oxyg en a n d the c o m b i n a t i o n of both a s a func tion of pH value. - 2 ) Reac tion p a r a m e t e r s for a c i d i c H 1i GNIF ICA TION. ^ ur labor atory scale trial s were - O /O d e ^^ - . . In the prese nce o f oxyge n , a r e l a t i v e l y small amoun t o f hydro gen p e r o x i d e alrea dy cause s a s i g n i f i c a n t effec t o n ligni n conte nt . This i s illus trate d i n figur e 4. The r e a c t i o n r e q u i r e s a n eleva ted tempe ratur e i n order to t a k e p l a c e corre ctly . For e x a m p l e , at 5 0 °( the p e r o x i d e conce nt rati i n i s nearl y u n c h a n g e d after one t » « urf a s i s the ligni n con tent . If the react ion t i m e i s p r o l o n g e , d the amoun t o f resid ual p e r o x i d e* d e c r e a s e' slow ly due to d e c o m p o s i t i o n , b u t dplig nific r ion r emains p o o r. If heavy metal i o n s are added , b p Pero xide c o n s u m p t i o n becom es more r a p i d , but w i * Hout a chang e i n l a p p a n u m b e r of p u l p. The addi tion - made with insi sten cies betw een 9 % a n d 25 % . There i s very littl e chang e i n d e 1 IGNL FICA TLON if the consi stenc y is increased Very s i g n i f i c a n t , how ^ ver , i s the effe ct of pH o n d e l i g n i f i c a . 14 Frfec t o f the a d d i t i o n o f o x y g e n or a i r to a c i d i c p e r o x i d e delig nific ation. - * of a chelate d metal for example , comp lex has the same result. lron - DTPA - The hydroxc nium i o n i s a strong electro philic a q e n t . It att .* n- s the lignin 's aromati c nuclei . Ring h y d r o n l a t n n , oxidati ve demethy lat i n n , - Detgrvfcoton °/o d i splacem ent of s i d e c h a i n s a n d oxidati ve r i n g o p e n i n g are t h o m a i n r e a c t i o n types. Radical reactio ns are rather unlikel y as a m a i n reactio n A* 5o a 4o 7 * 6 3o path . The homolyt ic cleavag e o f hvdroQ f n p e r o x i d e should take p l a c e under neutral onditio ns as well as under a c i d i c ones. As we k n o w from the 95 °C 65°C 5 reactio n paramet ers mention ed earlier , under 4 2o lo o3 MPa 3 2 pH < 2 02 neutral condit ions no d e 11 gnif 1 ca 11 on occurs. To prove the similar ity of the peracet ic acid 1 o.5 1.0 1.5 °/o HjOj a n d the p e r o x i d e reactio ns , w e perform ed trials with both compoun ds i n the absence a n d presenc e of oxygen. A d e 11 GNIF icatlon with peracet ic acid i s also intensi fied if oxygen i s present . Calcu lated on oxidati on equival ents , the peracet ic acid / oxygen aggrega te g i v e s the same result as - F i g u r e U. Effect of peroxid e concent ration PO deligni ficatio n. - in At 9 0° C , within one hour of reactio n time 1.5 % of t h e hydroge n peroxid e is consume d , and a 50 % reducti on of lignin conten t is the result . On the other hand , the reactio n seems to be very r a p i d if the chemica ls and the tempera ture increas e act on the pulp at once. Due to heating u p problem s on lab scale , we could not reach reactio n times below 15 minutes with a fair reprodu ceab i 1 11 y . With the good mixing system of our pilot p l a n t , we achieve d m a i n d e 1 LGNIF ICATL ON re action within the first three minutes. - strengt h , but by far with lower intensi ty tf > an the viscosi ty drop would lead one to expect. 3 ) The reactio n mechani sm The reacti ons of lignin model c o m p o u n d s with p e r a c e t i c a c i d or hydrog en p e r o x i d e under acidic conditi ons are descri bed i n the literat ure ( 2 ). Accord ing to these results , protona tion of the hydroge n p e r o x i d e and format ion of a hydroxo nium i o n i s the firfit reactio n step. 202 H* * HO* * H 2O more easily. Reactio n product s with lignin are the same. CHj - C O O O H + H + CHjCO OH + + 0H The formati on o f p o 1 yhydrox y 1 ated a r o m a t i c r i n g - The drastic reactio n conditi ons not only cause de 1 ignific ation. The pulp signif icantl y loses it 's viscosi ty . The steep drop i n v i s H . tempera ture level Obvious ly it n e e d s less acti v a t i o n energy. The formati on of the hydroxo nium i o n from protona ted peracet ic acid takes place systems i s the first lignin degrada tion step. The second step i s the oxidati on of these com - cosity surpri singly is not follow ed by a simult aneous drop in streng th. There i s a certain loss of breaki ng length and tearing the p e r o x i d e /oxygen combina tion. Perace tic a c i J / oxygen de 1 IGNIF ICATL ON takes place at a lower pounds to q u i n o i d systems. Both chemica ls , hydro gen p e r o x i d e and oxygen , may react here. Thus , the hydroge n p e r o x i d e w h i c h makes the importa nt initial reactio n step , - not consume d totally in seconda ry reactio ns. At least some of these is take place with oxyqen. If the degree of substit ution with electr on r i c h substit uents of an aromati c system r i s e s , the resonan ce stabili zation decreas es. An oxydati on reactio n becomes e a s i e r . Therefo re , the poly hydrox ylated product s o f the first reactio n step can be oxidize d with oxygen , which cannot - - react with the origina l lignin. Some hydroqu inones react easily with oxygen . under formati on of q u m o n e s a n d h y d r o g e n p e r o x i d e hydroqu inone derivat ives. the first lignin gradat ion step consume s hydroge n , but This reactio n i s used technic ally for the p r o ductio n of hydroge n peroxid e , u s i n g anthra de peroxide some of the subsequ ent steps m a y p r o d u c e p e r o x i d e once a g a i n , figure 5 illustr ates some of the possibl e reacti ons. The possibi lity for the formati on of additi onal p e r o x i d e which may - 15 -. - explains the effi react again with the lignin c 1ency of the combination of peroxide and oxygen furthermore, it explains the fact that even small amounts of peroxide and oxygen cause significant d e 1 1 g n 1 f 1 c a 1 1 o n. the POs - s t a g e. llulose , as mentioned earlier the ce^ The PO reaction causes some degradation of , There is a significant viscosity drop, but the breaking l e n g t h i s o n l y s l i g h t y d e c r e a s e d , It s e e m s a s if the alkaline conditions for the viscosity determination promote degradation of the cellu l o s e. E x p e r i m e n t s o n a l a b o r a t o r y s c a l e w i t h r e d u c t i v e b o r o h y d r i d e t r e a t m e n t a f t e r t h e P0 r s t a g e y i e l d e d b e t t e r v i s c o s i t y v a l u e s. T h e o x i - - corboxylic acids. dicorboxylic acids to carbonyl groups in the PO stage is very l i k e l y. T h e s e c a r b o n y l g r o u p s a r e a t t a c k e d u n d e r alkaline conditions by hydroxy anions and cleavage - of the cellulose chain is Alkali resistance of PO s and the amount of A ) A d v a n t a g e s a n d d r a w b a c k s o f t h e process. the application of PO There are several regulations governing pollution levels of effluents in Germa n y. The amount of COD should not exceed 200 kg 0? p e r t o n o f p u l p , f o r e a c h 5 0 k g o f C O D a penalty has to be paid to the authori ties w h i c h n o w a m o u n t s : o a p r o x i m a t e l y U.S $ . 1 5. T o r a p u l p m i l l p r o d u c i n g 100 ,000 t o n s o f facturers have to pay tion - T h e a c i d i c p e r o x i d e /o x y q e n process here offers a p o s s i b i l i t y. T h e e f f l u e n t o f t h e PO stage ^ could be evaporated and burnt tog ether with a n y c o o k i n g l i q u o r. Because no kations are p r e s e n t i n t h e P0 p r o c e s s , i t can be app 1 ied r t o ,« 1 1 s u l f i t e p u l p i n g t y p e s ; to the magnesium bar.ed a s w e l l a s t o t h e c a l cium based p ro rcises In the case of counter current washin , g - - tin - - amount of washing water should not be higher compared w i t h t h e s t a n d a r d process r e c o v e r y s y s t e m, i f s u l f u r i c a c i d i s used f nr acidification, corrosion should be no p : u * l e m. S m a l l a m o u n t s o f sulfuric acid are presen t in e v e r y s u l f i t e l i g u o r. T h e r e f o r e , * ht bleaching seguence should be started with iO d e l i g n i f i c a t i o n. - G e r m a n y. H e a v y m e t a l s like cadmium and mercury in the effluent are p u n i s h a b l e a s w e l l. A n o t h e r p o s s i b l e h a z a rd to t h e e n v i r o n m e n t a r e c h l o r i n a t e d c o m p o u n d s. T h e authorities plan strict limits on halogenated c o m p o u n d s in effluents, and penalties wil l be c h a r g e d o n t h e s e w i t h i n t h e n e x t y e a r. The amount of chlorinated compounds is determin ed not - - - d e c r e a s e d . T h u s, a d e 1 IGNI 1 c a t l o n p r o c e ss F w h i c h o f f e r s a c h a n c e f o r easy r e d u c t ion of the COD level f o r e x a m p l e, b y e v a p o r a . ^- The above mentioned penalties for COD in the e f f l u e n t a r e n o t t h e o n l y ones f o r w h i c h m a n u pulp per year, this means an amount of up t o U.S $ 3 ,000,000 i f t h e COD l e v e l i s very mter lower, - . is is PO treatment is higher , compared with standard s t r e a t m e n t. G e n e r a l l y , a f t e r a n i n t e n s i v e P O s t a g e s ^ no strong caustic treatment of the pulp can be r e c o m m e n d e d . This is a s i g n i f i c a n t d r a w b a c k f o r Reactions of lignin with peroxide and oxygen under acidic conditions and burning of the effluent e s t i n g f o r t h e m i l l s. - bleached pulps - - . the result. COD in the effluent of a bleach seguence with an f stage after intensive ing f i g u r e 5. - dation of hydroxy groups of the cellulose chain - in b y a n a d s o r p t i v e m e hod . N e a r l y a l l c h l orinated watersoluble lignin derivatives are detected with t hi p r o c e d u r e. V o l a t i l e p r o d u c t s s u c h a s chloroform are detected with a lower e f f i c i e n c y. T h e l i m i t f o r t h e a m o u n t o f T 0X i n t h e effluen t will be 2 kg per ton of pulp, for 1 kg of Tl , penalties will be the eguivalent o f U.S. $ I S , e v e n i f t h e l i m i t s a r e m e t. T o ill ist r a t e t h i s e c o n o m i c t h r eat to pulp mills, it must be mentioned that a standard bleaching seguence l i k e C f H H or C E H D produces up to kg o f TO', p e r t o n o f t » u l p . The l e v e l depend s - -- --- on kappa number and, na turally , mainly on the amount of chlorine appli e d. therefore , a strong tendency exists in Germany to reduce the kappa number to thp lowest possible level . Then also the a m o u n t s o f C O D a n d T 0X a r e 1 o w e r . In p r a c t i c e . t he kappa numbers currently i l o w e r , b ’r ;» u s e s o m e o f t h e h e m i c e l l u l o s e s whit a r e e x t r a c t e d n o r m a l l y i n t h e E s t a g e r e m a i n i n t h e p u l p . I f t h e e f f l u e n t o f t h e P(J s stagr is recycled with the waste cooking liquor , r a n g e f r o m 1 2 t o 1 7. O n l y s p e c i a l i t y p u l p s m a y h a v e k a p p a n u m b e r s h i g h e r t h a n 2 0. F o r s t a n d a r d p u l p s, C O D i s 6 0 to 8 0 k g per t o n, a n d TOX A t o is The highest amount of TOX is produced in the c h l o r i n a t i o n s t a g e. T h e r e f o r e , t h e e l i m i n a t i o n of chlorination gives the best reduction of the T O X v a l u e s. H y p o c h l o r i t e p r o d u c e s l e s s c h l o r i n a t e d c o m p o u n d s c o m p a r e d t o c h l o r i n e. E v e n l o w e r l e v e l s a r e a c h i e v e d i f c h l o r i n e d i o x i d e i s a p p l i e d. As chlorine dioxide is a very expensive bleaching chemical , the alternative bleaching sequences for the industrial application , so far , try to - u « e a s m u c h h y p o c h l o r i t e a s p o s s i b l e. - - f r o m 1 6 t o 8. reduced With two carefully buffered hypo chlorite stages, r final brightness of 88 is a c h i e v e d. I n t h e h y p o c h l o r i t e s t a g e , s i g n i f i c a n t l y less chlorinated compounds are produced in com p a r i s o n t o t h e c h l o r i n a t i o n s t a g e. T h e r e f o r e , even high amounts of hypochlorite produce less p o l l u t i o n t h a n c h l o r i n a t i o n. T h e d e m a n d f o r a c t i v e c h l o r i n e i s c u t i n h a l f b y t h e P0s s t a g e. I n s t e a d o f 6. A % a c t i v e c h l o r i n e i n t h e C E H H s e q u e n c e , 3.2 % active chlorine is distributed in two hypo c h l o r i l e s t a g e s. F i g u r e 6 i l l u s t r a t e s t h e d i f f e rences between the old C E H-H sequence and the n e w a l t e r n a t i v e , i n t e r m s o f C O D a n d T O X. is - - - ---- - -- - - COD k g/t 7o P04 Ao 3o pilot plant trials beginning in F e b r u a r y 1 9 8 5. - O t h e r b l e a c h i n g s e j u e n c e s w i t h t h e P O ij d e l i g m f i c a t i o n s t a g e w e r e c o n d u c t e d o n a l a b o r a t o r y s c a l e. As mentioned above , use of the full deligm'i cation power of the P0 stage requires a special s b l e a c h i n g s e q u e n c e. H o w e v e r , t h e r e a r e o t h e r - - - stage d e l i g n i f i c a t i o n. numbers of sulfite pulps can easily AO % of their initial be reduced to about 50 % l e v e l s. T h e r e f o r e , t h e E O P - s t a g e i s a n i n t e r e s t i n g alternative to recjce the amount of chlorine n e b b e d i n a b l e a c h i n g s e q u e n c e. A s e q u e n c e l i k e E 0? f ( E ) H D c a n c u t t i e c h l o r i n e d e m a n d b y more than half , compared with the standard C E H is very efficient in -- -- - - D s t a g e s. T h e T O X l e v e l is --- decreased simultan e o u s l y. For an additional reduction of chlorine demand , c h l o r i n e d i o x i d e n o r m a l l y w o u l d b e r e q u i r e d. T h e n e w P0 s t a g e c a n d o t h e s a m e j o b . W i t h - ll amount of hydroqen peroxide and a very s m a^ o x y g e n , t h e P0 s t a g e c a n b e u s e d a s a n a c t i v a t i n g - t o o l. E l e c t r o p h i l i c a t t a c k u n d e r a c i d i c c o n d i t i o n s prepares the residual lignin for subsequent nucleophilic cleavage reactions in the presence o f c a u s t i c s o d a. I n p r a c t i c e , t h i s m e a n s t h e P s- brightness ( An EOP PO L 5o H- H-s e q u e n c e w a s t e s t e d ^ combination of alkaline stages with peroxide and o x y g e n a n d a c i d i c p e r o x i d e /o x y q e n d e l i g n i f i c a t i o n. A0X k g/ t 6o in The iOP stage sequence I n t h e P 0s s t a g e , t h e k a p p a n u m b e r For these reasons the PO The kappa -- . residual COD of the two hypochlorite stages i s a p r o x i m a t e l y 3 0 k g p e r t o n o f p u l p. a p p l i c a t i o n p o s s i b i l i t i e s i f t h e P 0r s i s u s e d a s a n a c t i v a t i o n s t *» p o n l y . the Under I he aspect of reducing both levels a three stage bleaching C O D 's a n d t h e T O X 's s e q u e n c e h a s p r o d u c e d g o o d r e s u l t s: t h e P0s H H - 10 - 5 k g p e r t o n o f p u l p. - ij sequence produced a pulp with 85 E l r e p h o ) i n o u r l a b o r a t o r y. T h i s - 3 w a s w i t h o u t a n y c h l o r i n e a p p l i e d. S o t h e T O X l e v e l then is zero, likewise, the kappa number is 2 r e d u c e d t o a v e r y l o w l e v e l. 2o 1 - C- E HH . Figure 6 P0sHH -- C E H -H PC\ H H * Amounts of COD and TOX produced with d i f f e r e n t b l e a c h i n g s e q u e n c e s. - I h e I 0X v a l u e s a r e r e d u c e d t o a l e v e l s i g n i f i c a n t l y b e l o w t h e l i m i t o f 2 k q p e r t o n. H i e C O D Figure 7 gives the data for the amounts of chemi cals applied and the reduction of kappa number i n t h e s t a g e s. W i t h a l k a l i n e s t a g e s o n l y , t h e’ brightness increase would be limited to about 8 0 % r e m i s s i o n. I h e P 0 s t a q e i s a v e r y r a p i d o n e. F i v e m i n u t e s a r e a b s o l u t e l y s u f f i c i e n t - - f o r t h e r e a c t i o n. I f t h e t e m p e r a t u r e a n d t h e amount o f peroxide remain low. the strength losses are insignificant. 17 Chemicals Stage % unbleoched Brightness 14.0 54.7 20Z ,a5%OJ.15%NOOH 6.5 202.cSVoCV O7%H2S01 5.1 EOP O5%H POS a15%H P 15%H202.1%NaOH.3%Sil ic. . 02 o4%Cl D F i g u r e 7. Kappa Be 84.9 <1 893 32 133 o 9.2 Oxygen bl 19 124 o 87 POs Oxygen bl 12 117o 83 Conditons in 0 1.5%NaOH. o 3 MPo Oj.12%conc ,1oo°C. 1.5 h •• P0S o.75%H 202.2%H2S04.o.3 MPa 02.12%conc.95°C. a5h Bleaching of sulfite pulp with the s e q u e n c e C O P P O P. - unbleached ‘ 34 F i g u r e 8. - - As mentioned in a previous paper, an EOP stage 1 i n c r e a s e s t h e c l e a n l i n e s s o f t h e p u l p. T h e r e f o r e , t h e E O P P Os P b l e a c h e d p u l p s h a v e t h e s a m e o r a slightly better cleanliness already at a lower brightness level , compared with standard pulps, ror a n i n t e g r a t e d m i l l , t h e r e f o r e , a l o w e r b r i g h t ness m a y s u i t d e m a n d s w i t h o u t a n y p r o b l e m s. 1 Viscosity Breaking length km (600 CSF ) dm3/kg Kappa Be r457 - -- - Treatment of kraft pulp with a PO s t a g e p r i o r t o o x y g e n d e 1 ignificaf 1 o n. - D e p e n d i n g o n i n t e n s i t y o f t h e P Os s t a g e , t h e strenght of the pulp is somewhat lower than w h e n t r e a t e d w i t h o x y g e n a l o n e. T h e m a j o r d r a w back seems to us the necessity to switch the pH of the pulp from strong alkaline to acidic , a n d i n t h e o x y g e n s t a g e t o a l k a l i n e a g a i n. - I n p r i n c i p l e , t h e P Os p r e t r e a t m e n t s h o u l d b e a s useful as a nitrogen dioxide or an ozone pretreatment for the extended oxygen deligni f i c a t i o n o f k r a f t p u l p. If a higher level of brightness is required , the demand for bleaching chemicals like hypo c h l o r i t e o r c h l o r i n e d i o x i d e i s l o w. A f i n a l bleaching stage with hypochlorite or chlorine - dioxide easily yields a brightness above the 9 0 % r e m i s s i o n l e v e l. T h e a m o u n t o f T O X p r o d u c e d - - in such a H or D stage normally is less ' han 300 g of organically bound chlorine per 200 - - T h e i n i t i a l d e 11 g n 1 f 1 c a t i o n s t e p s E O P P O E P r e d u c e t h e d e m a n d f o r a c t i v e c h l o r i n e i n^ t h e final D-H stage to a level below 3 % even for m a g n e t i t e p u l p s w i t h k a p p a n u m b e r s a r o u n d 3 0. All results so far reported deal with sulfite p u l p s. T h e r e a s o n f o r t h i s i s s i m p l e: t h e r e a r e n o k r a f t p u l p m i l l s i n G e r m a n y. N e v e r t h e l e s s , w e a l s o m a d e s o m e p r o m i s i n g t r i a l s w i t h t h e P0 t r e a t m e n t o n k r a f t p u l p. A s f i g u r e B s h o w s , a P0 s t a g e c a n b e u s e d a s a p r e t r e a t m e n t s t a g e s piior to an alkaline oxygen delignification stage * Namely , PO pretrealment increases the overall b d e l i g n i f i c a t i o n r a t e. W i t h t h e s a m e r e a c t i o n conditions in the oxygen stage after PO pre s treatment , significantly lower kappa numbers a r e a c h i e v e d. p - - - . - 3) R e s u l t o f t h e p i l o t p l a n t t r i a l s. I The pilot plant was designed to show the f e a s i b i l i t y o f t h e P Os s t a g e i n t h e P O s H M s e q u e n c e. I f i t w o u l d f i t i n t o t h e o l d C E b H b l e a c h p l a n t i n s t a l l a t i o n s, o n l y s l i g h t c h a n g e s o f t h e e q u i p m e n t w o u l d b e n e c e s s a r y. I n t h e bleach plant of the B line of PWA Waldhof, a l l s t a g e s a r e r u n a t 10 % c o n s i s t e n c y i n upflow towers with displacement washing systems o n t o p o f t h e m. T h e r e f o r e , t h e r e t e n t i o n t i m e s a r e f i x e d. --- ---- - - - - - - t o n o f p u l p. - - - The PO -stage should fit within the retention E - s t a g e. T h e s e - r time of ^either t h e C s t a g e o r t h e a r e 1 3 a n d 9 0 m i n u t e s , r e s p e c t i v e l y. T h e p i l o t p l a n t 's r e t e n t i o n t o w e r w a s a s t e e l tube of approximateI > h e i g h t w a s 22 m 1 m in d i a m e t e r. I t s which corresponds to the - height of th • E tower. i The unbleached pulp was heated with steam a n d p i l e d i n a t o w e r. U l i f h a m e d i u m c o n s i s t e n c y g y r o p u m p t h e p u l p w a i t a k e n o u t o f t h e t o w e r. Because of the high r ipn ity of the pump , m o s t o f t h e p u l p w.v r e c y c l e d b a c k t o t h e - It c m t o p of t h e tower , a n d only a small amount was passed through t h e oxygen m i x e r and t h e upflow used a s t h e m a i n delignification step for su. ; t » p u l p s. The p o s s i b i l i t y for e v a p o r a t i o n tube . ' s stage s effluent reduces the C G D L e v e l significantly . Because a chlorina tion stage b t c o m e s unnecessary , the TOX values (organically bound chlorine ) a r e definitely ;i P. f a n d b u r n i n g of - In t h e oxygen m i x e r , all t h e chemicals - , -wereoxygen added. h y d r o g e n peroxide and sulfuric a c i d The pilot reactor t u b e had a n u m b e r of sample t u b e. The initial trials evaluated t h e effects of temperature and the amount of chemicals used. Here , t h e results correlated well with t h e laboratory data. The most i m p o r t a n t result was the r a p i d i t y of the d e 11 gn 1 fica 11 on r e a c t i o n. The m a i n part o f the d e 11 gn 1 fica 11 on r e a c t i o n was a c h i e v e d already after 3 minutes at the first s a m p l e valve. - - In combination w i t h alkaline oxygen/ p e r o x i d e stages , the amount of chlorinated c o m p o u n d s i n the effluent c a n b e reduced to a very low l e v e l. It i s also uc ful a s a pretreatment stage to d e c r e a s e t h e p o s s i b l e kappa level of a n oxygen stage i n kraft pulp d e 1 LGNIFICATLON. L iterature: 1 ) H.U. Suss , H. Kruger , Bleaching o f Sulfite Pulp with Oxygen , Peroxide a n d N i t r o g e n D i o x i d e , Das P a p i e r 3 ® , ( 11 ) 529 536 ( 1 9 8 6 ); H. Kruger , H.U. Suss , Oxygen / p e r o x i d e bleaching of s u l f i t e p u l p , Pulp & Paper , Canada 8 5 , ( 12) T 297 2 9 9 ( i 9 8 6 ; _ - With short reaction t i m e s i n t h e PO stage , s strength d a t a of t h e pulps w e r e comparable to h o s e o f the s t a n d a r d s e q u e n c e after the final - _ - bleaching stages w i t h h y p o c h l o r i t e. - The reaction i s i n d e p e n d e n t from p r e s s u r e ,there fore t h e height o f a towers i s of n o i m p o r t a n c e. Important for t h e delignification i s t h e m i x i n g intensity. for all pulps tested , the initial kappa numbers 2 ) J. Gierer , The Chemistry o f De 1 IGNLFLCAT:o n , Ho 1 zforschung 36 , ( 2) 55 6 6 ( 1982 ); W. Lawrence , R.D. McKelvey , D.C. Johnson , The p e r o x i a c e t i c a c i d o x i d a t i o n o f a lignin related O aryl e t h e r , Svensk Papperst . 1980 ( 1 ) 11 18. - - - 3 ) fossum , G.K ; Hagstrom S.L.; US Pat. 6 ,222 ,819 ; f e b. 5 , 1979 Kemp f , A . W. ; US Pat. 6 ,6 10 , 397 ; Dec 26 , 1980 Eckert , R.C. ; US Pat. 6.627 ,6 9 0 ; Apr. 13 , 1981 52 % of their To a c h i e v e a n additional d e c r e a s e of t h e k a p p a n u m b e r , the acidic p e r o x i d e /o x y g e n treatment was c o m b i n e d w i t h an oxygen/ p e r o x i d e delignifi - reduce a s well . v a l v e s , s o the reaction could b e followed d u r i n g the t i m e the pulp needed to flow through t h e of 16 20 were reduced to 55 initial levels. t h e PO - c a t i o n in the p r e s e n c e of m a g n e s i u m o x i d e. This two stage p r o c e s s p e r m i t e d a k a p p a number reduction of u p to 6 0 % in t h e pilot plant trials. The - - ^- - resulting PO OP g H H s e q u e n c e fits well into the e x i s t i n g bleach plant installation. PWA Waldhof will report about the detailed results in a n extra p a p e r. Cone 1 us i o n s: Delignification w i t h hydrogen p e r o x i d e u n d e r a c i d i c conditions is very much i m p r o v e d in the presence o f oxygen. The r e a c t i o n c o n be understood a s an initial e l e c t r o p h i l i c attack of the h y d r o x o n i u m k a t i o n a n d a s u b s e q u e n t o x i d a t i o n of the hydroxylated lignin b y oxygen or hydrogen p e r o x i d e . Acidic p e r o x i d e/o x y q e n delignification further extends t h e range of chlorine free bleaching . stages - 19 ^ brominated and treated as described by Saka / ' then examined in a Scanning electron microscone ( Hitachi - - SrTDY ON METIANISTTS OF KRAFT AND S 550 ) with an energy dispersive X ray analyser ( UXAC MAZIEST? 2000 ) , SUI.PT ^ P^T ICT: 7JCATT 0N OF RtOASSF WTT» ? SW-VIDXA Chen Guo- iong Wu , JiaLent of Paper Sci . and technology RESULTS AMD xiang \ oCULSION The delimification conditions and results during , kraft and mamesium sulfite pulping are shown in Tab South China Institute of Technology Guangzhou , China 1 , Fig. 1 and Fir:. 2 . During kraft pulning A. nqmu r,m - li gni Pi cat ion of bagnsee were studied rates in various morphological were also studied . . De ignification with SV. -FDXA The results showed that « ^°^ during kraft pulmn/r, . .i 2 . Complemental delignification at the same rate . But i to 135°C , and most of which was in S - X ywn ^ DS : Mechanism /as . . rises to 92.1 , ' ec removed , Delignification . . . In these mills , kraft or soda is the main process , and in one mill , the magnesium sulfite process is used . The mechanism of makm ^ in South China only - wood 'raft pulping had been known in many papers were not correct . The purpose . .- temp time curve of this studv was 2 . - . . wore listed in Tab . The 1 Pulp yields and klason lignin contents were . — lished with 3 L34 ilD/LA . Acid-soluble lignin 1 9 8 5 Wood and P u l p i n g C h e m i s t r y S y m p o s i u m . . . - cooking ° . and of bagasse may be run under 140 C . temp , may be omitted in the batch rates in CML and cc are as quick as in S. . Mame ium sulfite cooking of must be run at 162°C . for 1 hr . because of that the delimification bagasse 3 R v'KRENCFS ' (7) - - Lignin distribution was estab . Bagasse and its pulp wore . . . in whioh the absorption determination of acid soluble li /mi n of bagasse was run at 202 nm with its absorp 105 / begins rates in CML and cc are slower than that in S contents were determined by our laboratory * o method ,' l gecm . and 30 min. at 162 °C. The total removal rises to 80.2 * . The raw material to defibrize each other . . Kraft obtained according to standard methods but without tivity of . cooking cyole because of that the delimification ? - . Bulk delimification nhAse : This is the period from the time at max cooking conditions 1 reflux in secondary hydrolysis others CONCLUSION or seventy grams of bagasse were placed in eaoh one pot * ized completely - Eighty But it is also divided into another lignin Cooking was oarried out in a set of 1 liter pots . . 3 Residual lignin removal phase : This is the period of 30 min at 162 °C continuously The total limin removal rises to 88.00* The bamsse had been defibr 21.52$, acid soluble lignin 2.16$ and Pentosan in glvcerol bath time to 135°C to 162 °C . . main chemical compositions : Cellulose 48.48$, klason . . or which , the limin removal in S is faster than that in was depithed about 25/S in mill and has the 26.02$ ^ » 1* . to 135°C . The total lignin removal is 13.5 ^. in to EXPERIMENTAL lignin . temo ) i>~ in order to correct these conditions Bagasse — . . Initial delignification phase : This is the oeriod of 1 pulping of bagasse and to know its main causes with - . three plases: discover the mechanism of kraft and magnesium sulfite SEM :DXA . At tha ^ ime , the raw material has been defibrized completei '' is quite different the conditions of bagasse nulning , . cooking temp, and and removal preset "’Mn is tue n** riod from 3 Residual 1* r r 140°C . to 1 »0°C or l 60 ' C The total lignin removal pn , it may be seen t at is about 2 3$ ^ e bagasse ^ a’hen the conditions of wood pulping would be correct especially the max t*at : n S mtes * As compared with kraft nulping , magnesium sulfite pulping is an important raw material for paper . But The delimification » re higher than " 150°C . process phase : This is the kraft cookin ' needs not the time at 140°C INTRODUCTION Bagasse - period from 90 C amesium sulfite pulping , only 18 •5/« of total ligni . ° . to 140°C. The to ^al lignin removal ignin aj ( CMI ) and secondary cell wall ( s ) were tar.* . place rapidly and almost - ferent from wood kraft cooking in removals in cell oomor ( cc ) , compound mirid e lamella . - in S , CUT and ec by SEM KDXA . This is ' reat dif sulfite tal i _ run was removed up to 9 There are almost the same ra ? es of lignin removal ' has sig delimification prof * 3ses * . Bulk delignification phase: This is the period of temp , to 90°C . The total lignin removal is 74.9$ - it names . 74 ?$ of 1 T regions nificant different between kraft and basically , the process may be divided into three phases : The mechanisms of kraft and magnesium sulfite de UP . . .. ( 1 ) Kerr , A J ot a1 , APPITA 30 48( 1176 ) ( 2 ) Klsppe , P J Tanpi S 3 35 0970 ) .. . . ( 3 ) 01 m , L. and Tistad , 0 Svensk Panneutid 82 458 ( 1971 ) ( 4 ) Chen J o et. al Cellulose Chem . Technol . 65u ( 198? ) -. . ( 5 ) 3 tfcaf S etal . . Tapni 6 ( ^ 73 1978 ) 21 .t t o © E r o - . * »0 i 20 ' H c f C c n 150 - ? - « ^ "> 4 - f ?n r -» ' I • cc fio • * * CML 1S0 s •» f • / 5 * 0 . rO 1 . *ir 5 1 - 0 » o> in 1« ~ tlr.e ( HP. V ) «• inr "> #* rf otal Win during rvi^naalur ' rt *nd 3 /! • V * ( MULTIFORM NATURE OF RESIDUAL LIGNIN IN CHEMICAL THE PULPS multi form In this paper the of residue I nature lignins i s depictec with the aid of a fragment model ( Fig . 1 ) . The fragments in this model differ from in each other with ease the can oe they which removed from the pulp . Jorma Sundquist The Finnish Pulp and Paper Research Institute . . Box 136, 00101 HELSINKI , Finland P 0 THE FRAGMENT MODEL OF RESIDUAL LIGNIN High molar mass crosslinked lignin ( Fragment 1 i n Fig. 1 ) , lignin chemically bonded to polysaccharides ( LC - complexes , Fragment 2 ) resorbed and probably also lignin A differentiated residual for mode * lignin in residual lignin hypothetical has . In this model respective discussed been fragments fragments during . The kraft . Because of various cooking method , the i n theory , be removed from the pulp of these the use of as well as their bleaching chemicals , entangled i n the microstructure of fibe ^ walls ( Fragment 4 ) . the pulp ( 1, 2) patterns of faster , found means is this two - stage This Delignification, bleaching, method has been cause even residual 3 . step . number of . soluble products changing the reactivity . cooking By to be converted into modifying process 8 LE L I G N I N 5. ISOLU N S I D E THE F J IBRES 6 . SOLUBLE LIGNIN B T W T H E F I 8 RES the Flgure 1. The hypothetical fragment model of residual lignin i n unbleached pulp environmental However , only part of the residual lignin of pulp chlorination REMOVAL 8 Y EXTRACTION OR W A S H 4. E N T A N G L E D L I G N I N of fibers into water - soluble and alkali soluble degradation products Unfortunately , requires 3. RESORBED LIGNIN The purpose of to convert the residual lignin a - L I G N I N CARBOHYORATE 2. C OMPLEXES L. in unbleached - by . i 4 6 bleaching be chemical pulps that 1 CROSSLINKED L I G N I N REMOVAL NEEDS BLEACHING CHEMICALS 2 lignins , INTRODUCTION first . less harm to the environment , for example 5 the the possible during the cooking. . cause capillaries from acid products and t r y i n g to render soluble as many of the fragments as organosolv pulping, hydrogen peroxide, formic acid , acetic acid, methane peroxoic acid, ethane peroxoic chlorination i s which diffuses y hypothetical model can generally pat used to study ways of producing 1 conventional multistage macropores without KEY WORDS usually in lignin, pulp . is Soluble fibers i n th * outer l i q u i d of pulp ( Fragment 6 ) fully bleached pulps can be made really . inside the fibers ( Fragment 5 ) and also between residual lignin . I t consists of peroxoic acid cooking and one - stage alkaline peroxide bleaching. By this Chlorination entangled lignin ( Goring ' s The the developed softwoods lignin on depend for bleaching of a the include These lignin ) of k r a f t pulp diffuses extremely slowly from fragments lignin are molecules chlorine . without chemical and For cooking a pulp of favourable chlorine fragments that could , different bleachabi 1 i t y , too . and lignin six different types of pulps are different , which pattern , also into amount residual are formation during the However , there divided cooking significance properties problems can be removed only by essentially by chlorination . unbleached chemical pulp i s presented these 31 using bleaching chemicals , in the case of kraft pulp ABSTRACT method ( Fragment fibers during cooking onto belong to the category which or completely THE RESIDUAL LIGNIN OF KRAFT PULP During kraft cooking , wood becomes some somewhat resembles the formation - structure and The of the residual lignin can be made more inert substances remain in suitable with respect to bleaching. and dark colored, insoluble and way that of phenol resins chemically the fibers . fairly . Fragments l . . the crosslinked lignin and the l i g n i n 2, i e chemically bonded to considerable 198 S Wood and Pulping Chemistry Symposium ’ of the lignin i n the denatured and passive i n a polysaccharides , account for a proportion of the residual . lignin 23 experiments ( 3 ) Flow - through cooking that during kraft cooking dark - colored lignin is 3). In resorbed onto the fiber surface ( Fragment experiments at the FPPRI , bleaching of the lignin reaction The have shown as were chosen so conditions to and minimize condensation already from the start of the cook . During the first maximize lignin cleavage ( formic or acetic acid , cone , stage carboxylic acid adsorbed onto the surface of cotton linters during kraft cooking is difficult , even with chlorine , 60 and 80 % ) and hydrogen peroxide ( 20- 60 % o f the dried chips ) produce peroxoic acid , which is despite the fact that this lignin is present in only a very small amounts . Depending on the process Entangled interesting ( Fraction lignin 4) between fairly 2-4 15 - 25 % ) , the type of wood and the forms an h, of catalysts and stabilizers used , A the pulp the residual lignin in pulp . unbleached kraft the Kappa number of after is between 2 and 20 , the yield correlation has been found between its molar mass and its rate of diffusion ( 2 ) . Higher molar mass peroxoic acid stage lignin brightness 50 - 70 l ISO . diffuses more slowly . ° ( 70 - 90 C , parameters and quantitatively significant part consistency 1000 between agent . deligni fication selective good , dm 3 / kg 1300 and the viscosity is %, 50- 60 is the ( SCAN ) , and the According to our own experiments , the amount of soluble lignin present in the macropores and capillaries inside the fibers and peroxide bleaching . The dose of hydrogen peroxide is between the fibers ( Fragments in the outer and 6 ) appears to 5 The second stage of this method involves alkaline liquid of pulp around 0.3 - 0.6 times rather small , the pH is 10.5 , the reaction temperature be especially i f the pulp has been efficiently washed . Measurements made on an industrial kraft pulp ( Kappa bleached 35 brightnesses between and consistency before storage 12.3 % bleaching ) high- consistency in suggest lignin is distributed among follows : LC - complexes , crosslinked residual that six fractions as the number in percent , Kappa the time 1- 2 hours and the consistency softwood dm 3 / kg above 900 and the about 10 % . The pulps and hardwood 85 ° 80 C , have final % and viscosities 92 . lignin ( Fragments 1- 3 ) 45- 75 % , entangled ( Goring ' s ) After the peroxoic acid cook the pulp has far less lignin than after a kraft cook , The rapid cleavage reactions which take place under oxidizing lignin conditions ( Fragment 4) ( Fragments 5 and 6 ) 20- 50 % and and resorbed lignin soluble less than 5 % . probably prevent and condensation resorption , and also apparently cause the entangled lignin fragment to disappear . This is also suggested PEROXOIC ACID METHOD FOR PRODUCING BLEACHED PULP by the low molar mass In seeking a chlorine- free pulping method the aim was find ways of changing the typical to distribution of residual lignin kraft pulp In soluble lignin and , i f possible , also in favor of low molar mass lignin . Based partly on observations by Soviet scientists . •• ( 4 - 6 ) , a two - stage oxidative delignification method . has been developed on the laboratory scale ( Fig 2) (7 ). The chemicals used in this method contain only fully - bleached produces yields from har dwood . PINE SPRUCE BIRCH softwood the lignin ABSORBANCE 2 8 0 n m 1 PEROXOIC ACID LIGNIN ( PINE ) K R A F T LIGNIN ( PINE ) - N * 1» y\ and sodium , yet the nethod paper - type pulp in good raw - RCOOH M 202 70 90 * C 2 4h - material as well as \ 0 0 60 0.40 0 20 i + III YIELD 50 - 80 % KAPPA 2 20 10000 5000 3000 120 voo o. eo RELATIVE R E T E N T I O N VOLUME 1500 1000 MOLAR MASS - VISC SCAN 900 * 1200 - ( C A T 4 1Y S T S S T A B I L I found in the fragment described above for favor of carbon , hydrogen , oxygen of cooking liquor ( Fig . 3 ) . BRIGHT ISO 4 0 75 % t Figure 3. The molecular weight lignin in peroxoic distrib lion acid and of kraft cooking liquors ( 8 ) . HJOJ - p H 10 5 80 * C 1- 2 h Figure 2 . ?d YIELD 4 5 4 7 V + 1111 « VISC SCAN •9 0 0 BRIGHT ISO 8 5 9 2 % Two - stage oxydative method for prepan ng f u l l y bleached pulps without chlorine aid sulphur The residual lignin from peroxoic acid appears to be much more reactive treatment towards alkaline peroxide than is k r a f t lignin . This is indicated by the much greater brightness found for peroxoic increase in a c i d pulp when the two pulps are w i t h equivalent amounts oi the Kappa number ( Fig. 4 ) . bleached peroxide in relation to . 80 ZILBERGLEIT , M A , REZNIKOY V M , YUKHNOYICh , U . S S R pat Pulp semifinished product Z K 821614, April 15, 1981 ( CA 95 : 45056 A ) 6. KOSAJA, [H 202J 0.2 - KAPPA NUMBER PH 10; 80 * C 70 •• UNBLEACHED PULPS HC 0 0 H - H 202 ( 30 X ) 60 40 7 . KRAFT 20 0 10 20 . The bleachabllity of peroxolc acid pulps Figure 4 30 40 60 ... . .. .. G S , MIRONOVA , . T Ya ., PROKOPEVA . Y . D. Process for pulp ng . .. U. S. S . R . pat. 829747 , May 15, 1981 HC 0 0 H - H 202 130 % ) 30 .. M A , KOSELEVA , O BLEACHED 50 . .. . 5 BRIGHTNESS ISO % 6 0 KAPPA NUMBER LAAMANEN , L A , SUNDQUIST , J J , .. WARTIOVAARA , I Y . P , Method for preparation lignin containing from pulp rawmaterlal , .. . . Finnish pat 8 . ; FORSS, K of bleached . appl . 851156 , March 22, 1985 . SAGFORS , P -E. Hgnlnet 1 kokvatskan # - hur ser det u t ? Nordisk Cellulosa ( 1984 ) : 4 , and kraft pulps with hydrogen peroxide . 58 CONCLUSION The aro process pulping kraft peroxolc the acid - alkaline peroxide delignif cation method are examples of how the multiform nature of residual during the actual cooking, lignin can be rendered either how the residual lignin can be modified and toward the bleaching reactive more passive or more . chemicals The - producing fully bleached pine the only known way of using without pulp probably two stage method presented here Is chemicals at any temperatures stage either chlorine or The method works at low . and at atmospheric pressure sulfur . Although the process 1 s at present not economically viable 1n peroxide of terms consumption technology required 1s only Is a although the just being developed 1 t indication promising and that the present Industrial pulping methods , which have become almost an institution, can be replaced by new methods are less detrimental to the environmental . that REFERENCES 1. . Physicochemical aspects of GORING , D. A .I Pulp washing lignin removal in pulp washing . Mont Gabr 1 el , Quebec , Canada , Sept 83 , 77^29, 1983 , 19 - 25 . - 2. .. . 3 . ... .. GORING , D A I FAY 1 S, B D , YEAN , W Q , Molecular weight of lignin fractions leached Wood from unbleached kraft pulp fibers , J Chem Tech 4 ( 3 ) 1984 , 313 320 . . . - - . . J , I , STENLUND , B . , PALENIUS , P E Differences 1 n colour and strenght of kraft pulps from batch and flow cooking . Paperl ja Puu Papper o Tra 57 ( 1975 ) : 5 , 387 396 JANSON , SAGFORS , . - 4. . .. REZNIKOY , Y M. , ZILBERGLEIT , M A Paper pulp Intermediate product U S S R . Pat 761647 , Sept 7 , 1980 ( CA 93 : 222146 m ) . . ... . 25 ACID- BASE INTERACTIONS BETWEEN CELLULOSE AND 2.5 - ORGANIC MOLECULES Anders Larsson , Per Stenius 2.0 Benzoic acid A Phenol Pyridine U) Institute for Surface Chemistry -E 1.5 Benzonitrile O Box 5607 S 114 86 Stockholm Sweden — •E t h y l b e n z o a t e =M .O INTRODUCTION It is well known that the Lewis acid base con cept and its more modern generalizations give a comprehensive description of a large class of interactions between organic molecules ( 1 ). It has been successfully applied to predict solubi lities, solvent effects on chemical reactions and ma iy other soivation phenomena. Lately , the acid base concept has also been introduced in the theory of adhesion (2). Here it has been shown that basic polymers interact strongly with acidic surfaces and vice versa , giving rise to a high adhesion strength. - 5 0.0 0.0 C4 0.2 0.6 c 1.0 0.8 mmol / L Figure 1 . Sorption isotherms for the reference substances on microcrystalline cellu lose powder. - - Anisole Toluene 0.5 - - - tv * - • • .„ were also obtained for a bleached kraft pulp and a sulphite dissolvinc pulp. Anisole and ethyl benzoate are analogues of phenol and benzoic acid respectively , where the acidic groups have been blocked by etherifi cation or esterification. This transformation which does not affect the basicity to any greater extent causes a drastic decrease of the sorption. It can thus be concluded that the sorption of phenol and benzoic acid is closely linked to their acidity and consequently occurs on basic sites in the cellulose. Pyridine on the other hand is a pure base and can be expected to sorb at acidic sites. * m - METHODS To study the acid base properties of a surface , the interactions between the surface and a re ference set of acids and bases should be deter mined. These interactions can conveniently be measured as the extent of adsorption of the re ference substances onto the surface. We have in our experiments used a number of small aromatic molecules with known acid base properties as re ference substances. Their sorption by cellulose from hexane solution was measured by immersing dry cellulose in solutions of known concen trations. The extent of sorption was then calcu lated from the concentrations in the supernatant solutions after 18 h as determined by the UV ab sorbance. Hexane was chosen as solvent because it is essentially inert from the acid base point of view and thus gives minimal competition with the sorbate molecules for the sites on the cellulose. - - - - - - - - - 0.8 O) 0.6 Henry component O § 0.4 - - 0.2 Langmuir component RESULTS - Figure 1 shows the sorption isotherms for the re ference substances on a microcrystalline cellu lose powder. Obviously one group of substances show very weak sorption or none at all by the cellulose. This group includes anisole , ethyl benzoate and toluene (weak to very weak bases) together with benzonitrile ( weakly amphoteric). Pyridine ( a moderately strong base ) takes an Intermediate position whereas benzoic acid and phc? nol (amphoteric but predominantly acidic) show the highest extent of sorption. Similar results - 1985 Wood and Pulping Chemistry Symposium 0.0 0.0 0.2 0.4 c mmol / L 0.6 0.8 Figure 2. Model isotherm fitted to sorption data for pyridine on microcrysta 11 me cellulose The isotherms do not follow the Langmuir model . However , they can be fitted to the sum of a Langmuir isotherm and a linear ( Henry type) 27 REFERENCES isotherm according to the following equation: 1. GUTMANN D. The Donor Acceptor Approach to Molecular Interactions , New York 1978. - r •K * c L r = — r* * 1 + VC + KH • C - - where V is the sorbed amount in umol/g cellu lose , c is the equilibrium concentration in mmol/L , and are the constants of the Lang muir model and is the constant of the Henry model. Figure 2 shows the model fit for the sorption of pyridine on microcrystalline cellu lose. Figure 3 illustrates the time dependence of the sorption. A significant amount is sorbed almost instantaneously but the rate rapidly decreases and equilibrium is not completely reached after 24 h. - - 0.5 - 0.4 - U) o 0.3 E 0.2 0.10.0 0 T 5 10 TIME 15 h 25 20 Figure 3. Sorption kinetics for pyridine on macrocrystalline cellulose. Start concentration in solution 0.42 mmol /L. v • • C .. * CONCLU ; IONS Cellulose shows an amphoteric behaviour towards ’• ttllWsil the re:erence substances used. Presumably the 1 m active groups are the hydroxyls in the glucose rings. The complex sorption isotherms and the sorption kinetics might be explained assuming that both *rface adsorption and bulk absorption take ^ Place. The Langmuir component would then corresPOnd to adsorption on the exposed cellulose surfaces and the linear Henry component to bulk absorption in the amorphous regions of the cellu lose. The surface adsorption can be expected to - occur rapidly , whereas the bulk absorption is a slow Process involving diffusion in the cellu lose , which could explain the kinetics observed. - 28 2. FOWKES F.M. in Microscopic Aspects of Ad hesion and Lubrication , Ed. GEORGES J.M. Amsterdam 1982. - - of cellulose . i .n the S02 amine DMSO system was s • died by using 1H and 13C NMR spectroscopies. DISSOLUTION MECHANISM OF CELLULOSE IN THE SG DIETHYLAMINE DIMETHYLSULFOXIDE SYSTEM - - -- AKIRA ISOGAI, ATSUSHI ISHIZU AND JUNZO NAKANO - - RESULTS AND DISCUSSION 1) Reaction of methanol with SO > and amine m DMSO Fiacre 1 shows chemical shifts of 1H NMR spectra of various solutions related to the MeOH /SQ DEA DMS system. The OH proton of MeOH and the NH proton of DEA appeared at 4.1 and 1.3. pp. • , res pectively , and the OH proton of MeOH wa hardly influenced by the addition of S 02 into OH/DMSO. The OH proton of MeOH and the NH proto: of DEA are exchangeable each other. Thus , they show only one peak at 3.9 ppm , when they were mixed in DMSO. Noticeably , the chemical shift of NH preton appeared at 7.1 ppm in SO DMSO. This value indi cates the formation of a complex between DEA and SO2 By the addition of MeOH into the S DEA DMSO mixture (MeOH:S DEA = 1:1), a new signal appeared around 7.8 ppm instead of the signal at 7.1 ppm. This indicates that a new complex was formed between the OH proton and the aforesaid complex , Judging from the chemical shift , the formation of 0S H can be denied. 02 - DEPARTMENT OF FOREST PRODUCTS , ^-- - - FACULTY OF AGRICULTURE, THE UNIVERSITY OF TOKYO, BUNKYO KU , TOKYO, JAPAN 113 - - - ABSTRACT Dissolution mechanism of cellulose in the S0o amine dimethylsulfoxide system was studied by 13 using H and " C NMR spectroscopies. S and amine were found to form a complex in DMSO , and the S amine complex , in turn , reacts with an alcoholic hydroxyl group of methanol to produce a new complex. Also in the case of cellulose it was oved that all hydroxyl groups in cellulose form tne same complex with the S amine as that in the case of methanol. -* - - - - 02 02- - " 02- - KEYWORDS: Dissolution mechanism , Cellulose , Non aqueous solvent , Sulfur dioxide , Amine ^- -- 02- - - (CH 3)2SO > SO2 ~ DMSO DEA DMSO MeOH DEA DMSO MeOH DMSO OH , NH MeOH S DMSO SO2 DEA DMSO MeOH S02 DEA DMSO MeOH:S02 DEA= l:l(• 2:1 3:1 10:1 20:1 a 7 6 - 02 - - rNCH Hj ^ > CH 3 H ° - - - -NCH2CL 3 - - - 02- - - - - 02- - 02- - - cellulose ethers by using one of nonaqueous cellulose solvents , the S 02 diethylamine(DEA) dimethylsulfoxide(DMSO) system (1 4). These new cellulose derivatives have not only chemically reactive groups such as aromatic rings or double bonds but also unique physical properties such as thermotropic and lyotropic liquid crystals (4 ,5). The S amine solvents for cellulose was firstly found out by Hata and Yokota (6). They reported that DEA , triethylamine(TEA) and piperi dine can be used as the amine for the systems. Yamazaki and Nakao (7) reported that DMSO and the other 37 kinds of organic solvents containing small amounts of S and an amine can dissolve cellulose. As to the dissolution mechanism of cellulose in this system , several papers have been published by Hata and Yokota (6 ,8 ,9) , Yama zaki and Nakao (7), Philipp et al (10) , Turbak ( 11 ) and Hudson and Cuculo ( 12). However , their proposals are somewhat different each other , and the detail of the dissolution mechanism of cellu lose in this system has not been clarified. In the present paper , the dissolution mechanism - # - - - DMSO INTRODUCTION Recently , many kinds of nonaqueous cellulose solvents have been found , and the finding of these solvents made it possible to modify cellu lose in homogeneous and nonaqueous systems. The authors have succeeded in the quantitative prepa rations of about 30 kinds of tri O substituted - - 9 ov 11 y 1 5 4 ii > 11 3 2 1 ppm Figure 1. ^- - H NMR chemical shifts of various solu tions related to MeOH/SO , DEA DMSO system -- - When TEA was used as a component of the solvent system in place of DEA , the same results as those shown in Figure 1 were obtained. Namely , the signal of the OH proton of MeOH moved to locate at 7.8 ppm by the addition of MeOH to the S07 TEA DMSO solution. This value coincides with that in the case of the S 02 DEA DMS0 system. On the basis of these results , it is concluded that in the case of the S DEA DMS0 and SO. TEA DMSO systems the OH group of methanol reacts with the S amine complex to form a new complex as shown in Figure 2 , and the NH proton of DEA does not participate directly in the complex formation with the OH group of methanol. - - - - - 02- 02- - - - - - - 29 METHODS AND MATERIA LS EFFECT OF EXPLOSION OPERATION FOR EFFECTIVE UTILIZATION OF PLANT MATERIAL TATSURO SAWADA AND YOSHITOSHI NAKAMURA FACULTY OF TECHNOL OGY , KANAZAW A UNIVERS ITY , KANAZAW A 9 2 0 , JAPAN MASAAKI KUWAHARA FACULTY OF AGRICUL TURE, KAGAWA UNIVERS ITY , MIKI-CHO 761-0 7, JAPAN ABSTRAC T The objecti ve of t h e present researc h is t o obtain the b. ; ic experim ental data require d for practica l s y s t e m of separat ion of plant materia ls into their main componen ts by explosi on and its applica tion to product ion of biomass energy. The effects of operati onal conditi ons on propert ies and amounts of product s were examine d . It was found that the explosi on with high steam pressur e and short r e a c t i o n time was an efficie nt p r e t r e a t m e n t of plant materia ls for e n z y m a t i c hydroly sis and alcohol ferment ation. KEYWORD S: Explosi on , Energy. INTRODU CTION The chips ( 25 x 20 x 4 mm ) of L a n x leptole pis c o n t a i n i n g 20 30 % moistur e t o dry weight were used for materia l in the explosi n method. An explosi on apparatu s i s illustr ated i n the scheme as shown i n Figure 1. This apparatu s is con structe d of a steam g e n e r a t o r , a reactor ( its volume of 1.2 x 1 “ 3 w 3 ) t a r e c e i v e r for the explode d materia ls and a condens er equippe d with a cyclone to prevc nt condens ed water from g o ing back into the materia ls collect ed in the recei- - ver. The apparatu s was employe d at temperat ure up t o 275°C and m a x i m u m steam pressur e of 6.0 MPa. The chips ( L u 0 g ) packed i n the reactor were contact ed w i h preheat ed steam for a desired time and then release d into the receive r by opening a ball valve instant ly. Figure 2 illustr ates a schemat ic flow chart in the extract ion process es of he explode d samples. The extract s were freeze dried to give a m i x t u r e of hen icellul ose and water - soluble lignin , and methano l - soluble lignin , r e s p e c t i v e ly. The residua l materia ls i n the extract ion were heated i n 72 % aqueous sulfuri c acid for 4 hr to obtain insolub le lignin ( Klason lignin ) of wood which was weighed after drying method. . The explode d samples were sacchar ified with Meicela se at 37 C for 96 hr in 0.5 M phospha te ° buffer , pH 5.0. The substra te and enzyme concent rations were 2.0 % and 0.2 %, respect ively. The reducin g sugars were measure d by the Somogyi Nelson method . Many researc hers are looking at biomass , particular ly woody biomass , as a source of energy. The oil crisis s i n c e 1973 has led t o the significant develop ment of biologi cal convers ions such as enzymat ic hydroly sis and alcohol ferment ation of wood and grass. However, many technic al and problem s in the pretreat ment of biomass h a v e to be overcom e , for a practic al , efficie nt utiliza tion of biomass as an industr ial low c o s t energy. Recentl y , the autohyd rolysis and explosi on systems which use s t e a m with high t e m p e r a t u r e and pressur e for degrada tion of wood materia ls has attract ed attentio n. 1 In c o m p a r i s o n with other treatmen t systems , this system has the followi ng advanta ges: ( 1 ) The activity of e n z y m a t i c hydroly sis of cellulo se is high. ( 2 ) No chemica l i s necessa ry. ( 3 ) This system i s relativ ely low in energy c o n s u m p t i o n. In this study , the trial constru ctions of explosi on system were attempt ed for develop ment of the most efficie nt method of pretrea tment for energy utiliza tion of woods such as l a n x leptole pis. Condens er o economic Reactor Steam Generato r > ): T234 - 1 - . - - - - - T244 ( 1974) 8. HATA , K. AND YOKOTA , K. ibid 2 4( 9 ): 415 419 ( 1968) 9. HATA , K. AND YOKOTA , K. ibid 26(12 ): 571 577 ( 1968) 10. PHILIPP , B .. SCHLEIC !ER , H. AND WAGENKNECHT W. Cellulose Chem Te . hnol 9(3 ): 265 272( 19 75) 11 TURLAK , A. et ai Chentech 1980 : 51 57 (1980) 12. HUDSON , S. M. AD CUCULO, J .A. J or Macromol Sci C18: 1 82 ( 1980) I . GAGNAIRE , D• • MANGIER , D , AND VINCENDEN , M. J. Polym Sci Polvm Chem K.i 1 8( 1 ): 1 3 2 5 ( 1980) - ’ . 0 ppm El~ re 3 . Et - NCH 2CH ? l -V / - DMSO -OH - NH 0,10 *0 s Et 02 (I) Cell./S H - ' '' - - o R =H(DEA) or Et(TEA) - 02- 0 20 40 > Cell appeares as one peak at 59 ppm. By comparing chemical shifts of C 2 , C 3 and C 6 with those reported by Gagnaire et al (13), it was confirmed that the OH group of ceLlulose does not form any derivatives but forms the complex in the solutions. On the basis c ; these analyses , it was conclud ed that cellulose dissolves in the S amine DMS0 system by form: ,g a complex among the OH group , S and amine as shown in Figure 5. OH TMS ppm - - 3 AJL As shown in Figure 4 , there are no difference in the chemical shifts of carbons of cellulose •etween the two solutions , and the peak of C 6 - -NCH2CH - - - X-L (II) Ce 11./S Reaction of cellulose with S02 and amine in DMSO. 13C NMR spectra Figure 3 and 4 show the H and of cellulose solutions , respectively. As shown in Figure 3 , the signal of the protons due to the NH of DEA in cellulose/ , QH of cellulose and the S ~DEA DMSO , and due to the OH of cellulose in TEA DMS0 appeared around 7.8 ppm as cellulose/S a broad peak. This value coincides well with those observed in the preceeding model experi TMS * 4 of various solutions related to ^C-NMR spectraDMS 0 A i - 12 hr ? 1 x V *'• 1 - 1 Liqnin Cellu ose residue * ? ~r X 4 ti'jb /•• r ; \ i r. iw i r» v _ -[ oj >? • • bvxifc drying (c ) ti .* . .. ^ RESULTSrX \ » . xi i * i / (d - M*.- I mm -.rf.norU . -. * I' b i y , * f . The samples produced from wood chips by the hydroly sis with explosion are the materials of multiph ase which consist of the fibers broken into pieces and the broken syrupy liquid with a relativ ely large amount of water condensated from the vapor water. A part of shredded and fluffy solid causes an aromatic odor which is similar to the plant material which was burned by heating of steam. The features in shapes and sizes of broken fibers become very remarkable at a higher steam pressure and a longer reaction time J 9*(!8brO i• *. Figure 3 shows the micro photographs of wood chips of larix leptolepis exploded under various steam pressur es from 1.57 to 4.81 MPa for a period of 5 min in the hydrolysis reaction. i At the steam pressure of 1.57 MPa a part of fiber near - the wood chip surface was att , ked , but its original form remained. As the pressure . ^ rose to 2.55 MPa , the destruction of wood chip rapidly proceeded in the direction of filamental material and mudh of wood fibers were aroken into pieces in just short time. At the high pressure over 3.53 MPa the wood chip is broken into more fibrilliform particles which are destroyed beyond recognition with the syrupy liquid. Partic ularly, the effect of explosion at the pressure over 4.51 MPa is very remarkable, As seen from these pictures, the filamental materials made of wood chip by explosin consisted of a great many fibrilliform particles of various 32 v# .• v ' JXI* rtOi Jor! . ^: - • ^ samples. t(< V Soluble lignin Figure 2?* Flow chart on extraction of exploded • i Freeze Boiling point ^ (a ) Liquor 4 hr i •• , ' *** « | [72% H2 S04 ( 15 ml ) 1 Klason lignin " Ih i methanol ( 100 ml ) .» 1 1 measured by the naked eye or a microscope. Hemicellu lose CeWe residue «••1 sizes. Figure 4 shows the frequency distributions for both sizes of a shorter side (width) and longer side (length) in the filamental flakes from 400 to 500 pieces crushed finely. They were ( e) Figure 3. Photograph of exploded wood at reaction time of 5 min: (a) 1.57 MPa , (b) 2.55 MPa , (c) 3.53 MPa , (d ) 4.51 MPa , (e) 4.81 MPa Figure 4 (a ) illustrates the distribution of length in the shredded particles of wood chips exploded at a period of hydrolysis of 5 min under various pressure from 1.C 8 to 4.81 MPa. The raw materials in an almost normal distribution with the mean value at 25 mm and small mean deviation changed to the filamental materials which had the distribution in a wide range from the micro scopic size to 20 mm as the steam pressure increases up to 3.53 MPa. The rangi of distribu tion in particle lengths by explosin at 4.51 and 4.81 MPa became narrower in comparison with those below 3.53 MPa , and its mean length is below 0.05 mm. From these results , it seemed that the effi ciency of explosion on woDd chips was very large at pressure over 4.51 MPa. Similarly the distri bution of the width is shown in f igure 4 ( b). The trends in the changes of dintribution curves very similar to for the width by pressure Wc those for length. The range c v* idth in distri pressure became bution curve with increasing - - - narrower in spite of the relative ly wide range in the raw material . In contrast to the tenden / of of width , the range of length with increase in pressure elongate d in spite of the narrow range in the raw material . It is clear from this figure that steam pressure is one of the most efficien t factors on the fibril of fibers, especial ly, when the pressure is above 3.53 MPa. When the tempera ture reaches 243 C, which is inside the range ° of 231 to 253°C of thermal softenin g point of cellulos e , 2and saturate d pressure of 3.53 MPa , the mechanic al strength in the cell wall decrease s. 3 o PlMPaJ 4.51 4.01 Calc. E 2 a. i u e wore increase d. In contrast to the proc - 10:. of soluble lignin amount of Klason ligr. in decresed sharply , then changed to increase as z : \ e reaction time getting longer. The timing and j when the drastic change from the decrease of amount of Klason lignin product to its increase took place for a pressure was in fair agreement with the timing when the amount of souble lignin became constant regardle ss of autohydr olvsis time. It seemed that the producti on of souble lignin can not exceed a certain amount by the hydrolys is, however , the producti on of Klaso lignin producee ded progress ively as a result of the; condensa tion with compounds of high reactivit y except the soluble lignin or t . condensa tion among the lignins of the lower molecular weight which were produced by the exp. osion. The changes in the amounts of cellulos e and hemicell ulose under several operation conditio ns are plotted in Figure 6. The amount of cellulos e decrease d sharply in proportio n to the reaction time and pressure. On the other hand , the amount of hemicell ulose remained almost constant until the reaction time of about 20 min and the steam pressure of about 4.51 MPa. o l 50 0 100 L I>m] L Om] P ( MPoj 0 o LQ0 A V 1.57 2.55 3.53 Cole. 20000 40000 W [Mm] Figure 4. Size distribu tion of exploded wood fibers: ( a ) Length , ( b ) Width. Figure 5 illust rates a ratio of weight of soluble lignin and that of Klason lignin , <; and £ C|< to weight of exploded dry sample under various reaction times, t , in the steam pressure s of 2.55, 3.04 , 3.55 and 4.51 MPa. The amounts of soljble ignin mere d as the reaction time . Figure 5. Effects of steam pressure and reaction time on ratios of soluble lignin , and Klason lignin , dry weight of exploded wood. . 33 0.2 o A 255 3.04 353 451 A A A A 0 4> 0 (a ) 3 P [MPa] 0.6 I [mini I 0 0.1 v 5 10 20 X Cc A o 0.4 o 0.4 5 0.2 K 0 V I 10 0 0.2 20 t . Figure 6 Effects of steam pressure and reaction and time on ratios of cellulose , of hemicellulose, £ H to dry weight exploded wood. Figure 7 ( a ) and ( b ) show the relationship Figure 7. between enzymatic saccharification , X , and incubation time , 6 , at 2.55 and 4.51 MPa , Enzymatic hydrolysis of exploded wood: ( a ) 2.55 MPa , ( b ) 4.51 MPa. respectively. Enzymatic saccharification was defined as the ratio of weight of reducing sugars produced to that of exploded dry sample. Reducing sugars were measured by Somogyi - Nelson method as glucose. At 2.55 MPa , the small difference in the effects of reaction time on enzymatic saccharification was recongnized and their conversions were about 0.05 after 100 hr of hydrolysis. On the other hand , at 4.51 MPa , enzymatic saccharification increased remarkably w i t h incubation time and the large difference in reducing sugars was recognized . At 5 min of reaction time , enzymatic saccharification increased iharply and reached about 0.35 after 100 hr of hydrolysis. In the range of t ' 5 , © nzymatic saccha decreased with reaction t ^ me. ever il empirical models for the enzymatic hydre lysis of cellulose were proposed. The I P[MPb] It [ min] o A 2.55 3.04 3.53 4.5 I Of 5 20 9 V x o. i 0.05 ri 4 icat ion / orai ^ form proposed by Walseth is X = k Cn - o.oi i io 50 IOO 9 [hr ] (1) where i. nr. ! are experimental constant * Taking loqar rnma Doth sides of Eq.( l ) * s 5 Figure 8. Effects of explosion on saccharifica tion rate constant and reaction time. ( 2) log X = log k + n log 0 The relationship between enzymatic saccharifi cation and incubation time gave essentially straight line on a log scale as shown in Figure 8. The slope was proportional to the 0.34 power of X. Then , (3) n = 0.34 The value of the hydrolysis rate constant , k , was obtained as the value of X at 0 - 1. Figure 9 shows the value of k under several operational 3.53 , the value conditions. In the range of P of k increased with reaction time. On the other hand , in the range P 2 3.53, the value of k reached a maximum at 5 min and decreased with reaction time. Relationship of k and reaction time , k , was exprc sed as Eq.(4 ) using parameters a , 0 and y. (4 ) k = a / ( 3/t + 1 + t/y ) - - where a , 8 and y are maximum hydrolysis rate constant , hydrolysis rate constant at shorter time and hydrolysis rate constant at higher time. Figure 10 shows values of i , B and y in applying Eq (4 ) to the experimental data , a and 8 increased with steam pressure and enzymatic saccharification was high regardless of shorter reaction time. On the other hand , the value of y decreased with steam pressure and suggested a lower enzymatic saccharification at longer reaction time. From these results , it was found that the operation of explosion for a few minutes at a higher pressure was most effective for enzymatic hydrolysis of exploded wood . A - P [MPa] O 0.1 A 0 2.55 3.04 3.53 4.51 ^ 0.05 Figure 10. Steam pressure dependence of parameters a , 8 and y. CONCLUSION The experiments of explosion for the effective utilization of biomass were carried out under various operational conditions. Many of the various macromolecule compounds in wood converted to the lower molecular weight materials in just a short period by the hydrolysis with steam under higher temperature , and their lower molecular weight components were able to be separated relatively easily to the four components such as cellulose , hemicellulose , methanol soluble lignin and Klason lignin. This investigation will present the basic data required for practical system of separation of wood into main macromole cular components by operations of explosion and extraction , and enzymatic hydrolysis of exploded samples. - - o0 0 i 1 10 20 t REFERENCES 1. 2. Figure 9. Relationship between saccharification rate constant and reaction time. WAYMAN , M. and M. G. S. CHUA. Can. J. Chem. - 57( 10): 1141 1149 ( 1979) - MORIKAWA , H. Kagaku to Seibutsu 19(5): 286 291 (1981) 3. WALSETH , C. S. Tappi 35(5 ): 228 233 ( 1952 ) - 35 Trends in oxygen bleaching in Sweden During the 1960s and in the early 1970s , the HARMON I 21 MG BLEACH I NO TrOHDOLOOV WITH FUTURE ENVIRONMENTAL REGULATIONS - ALF DE RUVO VICE PRESIDENT, RESEARCH AND DEVELOPMENT SUNDS DEFIBRATOR AB S 851 94 SUNDSVALL SWEDEN - - Introduction The following summary is the result of a study of the concession decisions in Sweden during the past 5 1 0 years for all plants manufactu ring bleached sulfate pulp. The intention has been to find possible trends in the authorities' view of oxygen bleaching. - - The current status of internal and external measures in Swedish bleaching plants Of the fifteen sulfate mills which manufacture bleached pulp, eight have today oxygen stages for bleaching softwood pulp. Of these mills , one also bleaches hardwood pulp with an initial oxygen stage. One additional sulfate mill is planning to instal an oxygen stage for bleaching softwood pulp. The portion of chlorine dioxide in the chlo rine stage for softwood pulp varies between a few per cent and 20 per cent. The percentage for the bleaching of hardwood pulp varies between a few per cent and 90 per cent. All fifteen sulfate mills which manufacture bleached pulps have sedimentation ponds. However , at one mill , all or part of the bleach plant waste water is taken directly past the pond . Five of the mills currently have aerated ponds. A deci sion to construct a biological purification system has been reached at another. In certain cases , all the bleach plant waste water is not led to the aerated pond. One mill uses external purifi cation of bleach plant effluents in the form of adsorption on lime sludge ( " the lime sludge method " ) and another uses ion exchange treatment. One mill has both an oxygen stage and an aera ted pond. At another mill , with oxygen bleaching , a decision has been made to instal biological purification. At the mill planning to instal an oxygen stage , an aerated pond is already in use. At another mill with an aerated pond , permission has been granted to instal extended cooking in combination with improved washing and an increase in the use of chlorine dioxide in the chlorine stage, as an alternative to introducing oxygen - - - bleaching. Swedish pulp and paper industry concen * rated its environmental protection efforts primarily on the environment in and around the mills. Large resour ces were invested in an attempt to reduce the dis charge of oxygen consum ng substances. The first oxygen stages started operation in the beginning of the 1970s and represented an an swer to the demands of authorities to reduce the discharge of BOD7 , lignin and color. Often , con ditions were formulated so that companies could choose between an oxygen stage and external puri fication ( 1 ). During the mid 1970s, the National Swedish Environment Protection Board regarded oxygen bleaching in combination with conventional final bleaching as a "standard requirement " in new mills. In the opinion of the Environment Protection Boar 1 , oxygen bleaching was a first step towards a closed bleac: plant ( 2 ). External purification methods for b. ?ach plant waste liquors and ion exchange and lime sludge methods were regarded as an ac ceptable alternative to oxygen bleaching for existing installations ( 3 ). During the latter half of the 1970s, environ mental concerns shifted to an increasing extent towards the long term effects of discharges in time and space. To an increasing extent , discus sions began to be concerned with the reduction of the discharge of chlorinated organic substances. As a result , the Environment Protection Board 's demands were increased to encompass oxygen bleaching and measures to reduce these substances. Among the most important of these measures was the exchange of chlorine for chlorine dioxide in the first bleaching stage as well as the external treatment of bleach plant discharges through aerated ponds , and the ion - exchange and fenox methods. Mill closure measures through recycling of portions of the waste liquor from the first alkali extraction stage were also demanded by the Environment Protection Board ( 4 ). A noticeable trend during this period was that the National Swedish Franchise Board for Environ ment Protection deferred final demands and re quirements with respect to bleach plant dis charges. At the time , the Franchise Board for Environment Protection decided to await the re sults of the Swedish Pulp and Paper Association 's then ongoing project , " Environmentally safe manu facture of bleached pulp ". During the period of deferment , mills were usually ordered to investi gate " technical and economical possibilities " to reduce bleach plant discharges through various measures ( 5 ). - - - - - - - - - - - - - 37 During r e c e n t years, joint research carried o u t of by Swedish industry h a s s h o w n that t h e r a t e s u borganic or delignificaticDn and t h e transfer ances t o bleach plants are t w o primary factors affecting conventional p a r a m e t e r s and toxicity in bleach plant discharges. D u r i n g t h e c u r r e n t decade, the Environment Protection Board h a s also b e g u n t o a n increasing e x t e n t t o insist on a re duction in t h e Kappa number in c o o k i n g in conven tional bleaching and in o x y g e n s t a g e s, a s well a s on conditions for washing losses ( 6 ). In addition t o demands for oxygen s t a g e s and aerated ponds , r e c e n t requirements h a v e a l s o been specified for Kappa n u m b e r reductions , certain proportions of chlorine dioxide in chlorine s t a g e s and improved washing ( 7 ). It is in teresting t o n o t e that one mill with an e x i s t i n g aerated pond h a s received permission t o instal extended cooking in combination with better w a s h ing and an increase in t h e level of chlorine dioxide , a s an alternative t o oxygen bleaching ( 8 ). In summary , it may be said that there w a s a noticeable trend that m i l l s were either ordered or themselves undertook t o instal oxygen s t a g e s d u r i n g t h e 1970 s. During t h e latter half of t h e decade , demands increased t o encompass o x y g e n t a g e s i n c o m b i n a t i o n with additional internal nd external measures. Concession decisions 1 Vallvik Sk ^ tskar Korsnas 2 SkutskMr Ka rlsborg 6st rand 4 V 3 r6 Morrum Gr uv6 n Gruvbn Husum 5 Mdnster & s Monster s Skogha 11 ^ fist rand VMrb M5 rrum Norrsundet 6 0strand Gruvhn Nort undot Husum 7 B Husum Kar 1 s h o r g Karlsborg 38 June 8 , 1973 April 1 , 1974 1 , 1974 April June 10, 1977 December 13 , 1978 November 2 0, 1973 June 25 , 1980 i October 28 , 1980 October 2 , 1982 Apr i 1 6 , 1982 June 29 , 1982 May 26 , 1977 April 29 , 1981 January 15, 1 9 7 9 A p r i l 1 0, 1980 June *2 +c * 1980 October 28 , 1980 October 7 , 1981 A p r i l 10 , 1980 October 2 , 1980 October • » 1981 June 29 , 1982 June 2 9 , m 2 Dec 'mbor ! 4 I M K 2 January J 2 , 1 ‘ 4 . FUTURE TRENDS IN BLEACHING TECHNOLOGY D e l i g n i f i c a t i o n with an alkaline o x y g e n s t a g e A basic precondition for the use of a n alkaline oxygen s t a g e in a d e l i g n i f i c a t i o n operation i s that t h e development of t h e s e l e c t i v i t y for t h e d e l i g n i f i c a t i o n is better than t h e final p h a s e of the sulfate cooking. The v i s c o s i t y and Kappa number of t h e cooked pulp are d e t e r m i n i n g f a c t o r s for t h e technical and economic results of the process in t h e oxygen s t a g e. A high intrinsic v i sc o s i t y ( < 1 200 dmVkg ) for a Kappa number around 30 with small variations , is a precondition for a g o o d result. The development of c o o k i n g technol o g y greatly furthers the possibilities of im proving economic and environmental effects b y using an oxygen s t a g e a s the first s t a g e following cooking. T h e introduction of high sulfidity , a t mospheric s t e a m i n g and c o m p u t e r control has, # generally speaking , increased t h e possibility of being able t o deliver a high - v i s c o s i t y pulp with stable Kappa number from the digester t o t h e o x y gen s t a g e. Modified c o o k i n g processes h a v e been developed and tested on a large scale. It is possible t o cook t o around Kappa 25 w h i l e m a i n t a i n i n g vis cosity. T h e total yield will b e somewhat lower and t h e consistent q u a l i t y of t h e pulp has n o t a s y e t been ensured on a full scale. However , t h e know - how gained can contribute t o t h e production of a pulp with Kappa n u m b e r s of 28 - 30 with con sistently better viscosity. Therefore it is very likely that the c u r r e n t cooking -oxygen process can be further developed u s i n g improved washing methods now under development so that Kappa n u m bers of 12 - 14 can b e achieved without a d v e r s e l y affecting t h e quality of t h e pulp. This means ( c o n t r a r y t o what has been reported in certain c o n t e x t s ) that the improved c o o k i n g process should n o t be regarded a s an alternative t o o x y g e n bleaching , but as a complement , which i m p r o v e s the p o s i t i v e effects of the o x y g e n s t a g e on t h e p r o d u c t i o n economy and the environment . In r e c e n t years , i t has been demonstrated that it is possible t o a c t i v a t e the unbleached pulp using certain p r e t r e a t m e n t s so that t h e selectivity of a subsequent o x y g e n s t a g e is g r e a t l y improved. Pretreatment with chlorine p r i o r t o t h e oxygen s t a g e considerably i m p r o v e s the selectivi t y o f the o x y g e n s t a g e. Because of c o r r o s i o n pro blems, however , it is hardly possible t o r e c y c l e the spent liquor tc the closed liquid and r ecovery s y s t e m of the pulping process. Pretreatment with g r e e n liquor , peroxide, ozone or nitric oxides in acid meJia g i v e s positive results. T h e best results for sulfate pulps are achieved with nitric oxides. In Sweden , professor Olle Samuelson , together with MoDo, has carefully studied the treatment of unbleached sulfate pulp with nitric oxides prior to an oxygen stage. Amazingly good results have been reported in terms of pulp yield and especially for pulp vis cosity after the oxygen stage. It appears that pulp quality can be maintained at a high level down to Kappa numbers of about 10. It also appears easier to control with regard to the viscosity of the pulp. Ozone may pose an attractive futurl alternative as a complement to oxygen bleaching , primarily as an activating pre stage. - - Closed systems The basic idea underlying the increased u * o f non chlorine, non corrosive chemicals in the bleaching plants is to recycle waste liquors to possible to increase the degree of delignification the recovery cycle. It is then possible to burn 75 per cent from the current average of 50 per to the organic matter ana recover sodium. cent A Swedish pulp mill is cur ntly recyclin: ' These results have been so promising that a the liquor from the OE stage * o the recover ; group of Swedish companies MoDo , Sunds Defibrator , cycle. By using oxidized white liquor in hot: AGA and Kema N bel the 0 and OE stages , and using the flexibility have decided to finance a pilot plant project to facilitate the development of the chlorine dioxide production , the plant has of equipment and to evaluate the process from the succeeded in introducing an economical system technical and economic perspective. A thorough with low discharges. analysis and characterization of the effluent from A bleach plant for a brightness of 90 % ISO the bleach plant will also be conducted as well as with two pressurized oxygen stages and satis of the health hazards in the environment within factory washing systems may be designed with the mill. only chlorine dioxide as a bleaching agent . The bleaching plant is closed to a hich degree Hydrostatic oxygen stages with a water consumption of only 5 m 3/ton of pulp. Oxygen reinforced alkali extraction stages A bleed of 0.5 1 m /ton is assumed. This waste have been shown to be both an effective and eco liquor may be treated before it is released to nomical complement in the bleaching sequence , the recipient. If the brightness target is suffi especially as the first alkali extraction stage. cient for the pulp' s end use , application of a By raising the height of the tower, the effecti hydrostatic extraction stage may be a viable vity of the delignification process can be in alternative to the pressurized oxygen stage. creased . This variant may also be introduced as a first stage in special cases such as with hard wood sulfate pulp, sulfite pulp , or other pulps where a lower delignification (around 35 per cent ) is acceptable. A sequence of the ( EO)(CD )(EO )D type may be an attractive alternative. It has also been demonstrated that the replace ment of the hypostage with an alkali oxygen stage is favorable for both birch and pine sulfate pulp ( for example , a (CD )E( EO)DED sequence ) . - - . - - - - - - ^ - - - - Ozone The introduction of ozone into the bleaching process has so far been handicapped by its aggres - sive character, which reveals itself in difficul ties in controlling pulp quality ( this applies to the process with high concentration ), and its cost , which as a result of the low energy and conversion yield , has remained at a high level. Ozone produc tion technology has developed gradually ; important proqress has been achieved in recent years. It can therefore be expected that an introduction of ozone in certain positions will be economically feasible within the near future. Low concentration methods ( around 3 per cent pulp consistency ) appear to be - - 39 experimental data presented are suggestive rather ON THE REACTION BETWEEN ALKYLKETENE DIMERS (AKD) AND than conclusive at the present stage. It must: be realized that the amount of AK.D that CELLULOSIC FIBERS can be expected to react Is very small. According to - LARS ODBERG our experiments at STFI , only 0.01 0.04 Z of a fully TOM LINDSTROM sized sheet consists of reacted AKD. This amount gives 5 Z monolayer coverage of the BET area , and SWEDISH FOREST PRODUCTS RESEARCH LABORATORY (STFI) this surface coverage has In our st idles been shown - to give hydi ophoblcity t * * a paper surface. PAPER TECHNOLOGY DEPARTMENT P.0. BOX 5604 S 114 86 STOCKHOLM, SWEDEN Since very weak signals were anticipated , a modern FT-IR spectrometer (Bruker IFS- 113 ) was used , - IR STUD IF.S v operating In the Internal reflexion mode using a - KRS 5 crystal . The absorption bands of the AKD , which we have ex.mined closely are those of the - * C bond) and 1850 lactone ring at 1720 era” (C l 0 bond) and the CH stretching cra (C ” - - vibrations at 2917 cm 1 and 2849 cm” . ^ To avoid possible complications from dispersants . A 80 g /m etc., the AKD was dissolved In THF INTRODUCTION Alkylketene dimer sizing agents have been known for almost 40 years for the sizing of paper under neutral and alkaline conditions. The efficiency of these sizing agents has been ascribed to a chemical reaction with the celluloslc fibers. In papermaking , the alkylketene dimer size is used as a cationic dispersion. In a series of experiments Llndstrora and coworkers (l) have followed the development of sizing and the extent of reaction as a function of time and solids content of the 9heet. In these experiments the reaction between AKD and cellulose in the formed ' wade from dv.c rilled b cached softwood kraft was impregnated with this solution to gtve various percent ges of AKD. After drying in air , the sheets were cured at U0 C for 30 min. After the curing , ° the sheets were extracted by first swelling the . sheets in H 20 and then extracting them with THF (1) - IR spectra of samples were run after impregnation , after curing and after curing + extraction. If the reaction occurs , a (3 keto ester Is formed and one expects carbonyl bands to appear at 1745 ctn l and 1720 era"! and the xactone bands to disappear. - “ The observation that could be most easily made was that the Intensity of the lactone ring vibrations sheets was Inferred from changes In the proportions relative to the CH vibration of the alkyl chain of extractable and unextractable AKD (radioactivity). changed. It is difficult to Interpret the data In terms other than those of a covalent reaction , but extraction does not provide unlequlvocal evidence for reaction. sheet As an example , l C * ^ c lactone)/ I , ^ sheet. When the29 ^ (C-H) was 0.35 In the impregnated sheet was cured , the ratio was 0.27 and after extraction It was 0.20. The easiest explanation is Therefore a series of Investigations was started to obtain direct experimental (eg. spectroscoplcal) of course that the relative Intensities have changed evidence for a reaction. will of course be greater when most of the unreacted This paper presents some due to reaction with the lactone ring , This effect preliminary data related to this issue. AKD has been extracted from the sheet . That all the AKD cannot be extracted from the sheet in this case REACTION BETWEEN AKD AND CELLULOSE is most probably due to the fact that the AKD was not celluloslc gations on the reaction between AKD and - added as a dispersion but as a THF solutlon (Internal During the last year , three different Investi trapping In the cell wall). fibers liave been reported by Roberts and Garner (2), The roost direct Indication of a reaction between Rohrlnger, Bernhelm and Werthemann (3) and Merz , Rohringer and Bernhelm (4). These authors have the cellulose and the AKD Is, however , the appearance of a weak IR bond at approximately 1745 cm~ l. Investigated the reaction with model substances , This band Is most clearly seen In the sample that has radioactive labelling , analysis of extractives , IR - technlques and DSC technIques. - - Without discussing been both cured and extracted (see fig.). The Intensity of this small band gives i concent rat Ion of these Investigations , the authors conclude that they reacted AKD in the sheet of 0.047 Z, a figure which find no evidence of a reaction , although the is of course very approximate. The extinct m 41 coefficient for the carbonyl band has been estimated from the case where the AKD had reacted with CH 3OH. ACKNOWLEDGEMENTS We should like to thank Drs Bo Liedberg and Jaak Suurkuusk for valuable contributions to this work. REFERENCES 1. LINDSTROM, T. Proceedings XXI EUCEPA Conference 1984. A more detailed account will be given in a series of articles in Svensk Papperstidning. 2. ROBERTS, J.C. and GARNER , D.N. Tappi 68(4): 118 (1985) 3. ROHRINGER , P., BERNHEIM, M. and WERTHEMANN , D.P. Tappi 68(1): 83 (1985) 4. MERZ, J., ROHRINGER , P. and BERNHEIM, M. Das Papier 39(5): 214 (1985) Wavenumbers ( c m - 1 ) . IR 6pectrura for a cured and extracted 6heet. The baseline used in the Figure 1 calculations is also shown. CALORIMETRIC INVESTIGATIONS Another way that could be used to trace the •' , . If the reaction 16 to follow it calorimetrically - value 0.047 Z obtained in the IR study is taken and we estimate an enthalpy of 100 kJ , we can expect a total evolution of heat of the order of 100 mJ per gram of pulp. A sensitive calorimeter needs at least an hour to come to equilibrium after the sample has been placed in must be t , which means that the temperature lowered to ensure that the reaction has a half life of at least a couple of hours, This also me ms that the calorimeter must be able to detect a couple of pW. It was therefore decided to work at 40°C and with the LKB Biological Activity Monitar - •* Calorimetert which has this level of sensitivity. A pulp sample impregnated with dlchloromethane and a pulp sample impregnated with a 1 Z solution of AKD In dichlor * methane were placed in the calorimeter. In the sam le with AKD there was an excess of generated heat . When this excess heat was plotted logarithmically igalnst time a straight line was obtained that give a half life of the reaction of 8.6 . if the activation energy and the reaction rates h determined at itgher temperatures (l) are used , a ha 1 l i f e of 5.2 h would be expected , This is as close an agreement as can be expected for this type # . experiment 42 v - - DELIGNIFICATION OF HIGH YIELD SULFITE PULP WITH ALKALI - Alkali cooking (second stage cocking ) was car: led out with 1 N NaOH. Wood to liquor r tio was * :15. Oxygen alkali cooking also was >erformed at same conditions as the above . - NAM SEOK CHO DEPARTMENT OF FORESTRY COLLEGE OF AGRICULTURE AND ANIMAL SCIENCE YEUNGNAM UNIVERSITY, GYEONGSAN , 632 REPUBLIC OF KOREA ABSTRACT Sodium bisulfite ana sodium sulfite cooking of beech wood meal to a nigh residual lignin content followed by a further aelignification with alkali was investigated. Comparisons Detween the single stage cooking anu tne oxygen alkali cooking were also made. Two stage cooking gives a nigh delignifica tion rate and acceptable pulp yield as compared to tne single stage cooking. It is , therefore , concluded that sulfonic acid groups introduced into a lignin molecule Dy sulfite pretreatment contribute to the acceleration of the delignifi cation reaction Decause of their electron - - - - - - - witnarawing property. KEY WORDS : - - - Single stage Cooking , Sulfite Pretreatment INTRODUCTION Pulping with sodium sulfite would appear to De tne most promising approach because the pH of tnese chemicals in aqueous media lies in the preferred range and sulfite ions have the ability to stabilize carbonydrates against the peeling reaction. However , sodium sulfite is very slow in its pulping action as compared to kraft cooking liquor. ° - - - - - delignification rate 2 times higher than that of single stage cooking , and differences or del g - - nification between two different cooking methods are seen to be maintained even after 120 min. cooking time. As the temperature is raised to lbO C, the delignification rate at the initial ° stage showed relatively large differences (12 18%), but these differences gradually became - smaller with increasing cooking time , In the case of single stage cooking , on the other hand , a continuous increase in the delignification - rate was observed even after 18 U min. cooking . 60 - * c high residual lignin content followed by a further delignification witn sodium hydroxide has oeen investigated. 03 50 o O 3 3 f 3 In the present paper , sodium bisulfite ana sodium sulfite cooking of beech wood meal to a O NaOH O NaHSOg - NaOH 40 °3 - NaOH Na S 2 c Ol a> O EXPERI MENTA L 30 - Extractive free beech wood meal was treated Dy sodium Disulfite and sodium sulfite cooking liquors to De about du % pretreated yield y/L NaHSOj and 31.2 g/L No CO 3' and souium 8uifite cooking liquor consisted of JO g/L of N* s0j * 1 1 20 0 ^ . 1 120 90 60 Cooking Fig o o o . Sodium Disulfite cooking liquor was composed of * - ° - Therefore , a two stage pulping method using sodium sulfite or sodium bisulfite in the first stage and another mild sulfide free pulping in tne second stage seems to De a promising process. ^ - - Delignification , Two stage Cooking , sodium bisulfite or RESULTS AND DISCUSSION In tne case of 12G C cooking temperature , ° pulp yield decreased with increased cooking time , considerably during the initial t> 0 minutes, and then levelled off. After the sulfite pretreatment, there was evidently a decrease in pulp yield as compared to the single stage cooking. As the cooking temper ature was increased to 160 C, pulp yield decreased significantly as compared to the former. Also, pulp yield differences retween the two stage and the single stage coo mgs were getting closer at the final stage of cooking .J than at 120 C. As can be seen in Fig. 1 anc 2, the delig nification rate is dependent on the cooking temprature and cooking time. Single stage alkali cooking shows 23.5 27.6 % of low deligni fication rates. Two stage cooking resulted in - t i m e, min . Effect of two stage cooking on delignif ication of pulp ( 12l) C > ° . 43 - jut - DELIGNIFICATION OF HIGH YIELD SULFITE PULP WITH ALKALI - Alkali cooking (second stage cocking) was led out with 1 N NaOH. Wood to liquor r . tio - was i: 15 , Oxygen alkali cooKing also was . •er formed at same conditions as the above . NAM SEOK CHO DEPARTMENT OF FORESTRY COLLEGE OF AGRICULTURE AND ANIMAL SCIENCE YEUNGNAM UNIVERSITY, GYEONGSAN , 632 ° REPUBLIC OF KOREA ABSTRACT Sodium uisulfite ana sodium sulfite cooking of beech wood meal to a nigh residual lignin content followed by a further delignification witn alkali was investigated. Comparisons - between the single stage cooking - ana tne oxygen alkali cooking were also made. Two stage cooking gives a nigh delignifica tion rate and acceptable pulp yield as compared to tne single stage cooking. It is , therefore , concluded that sulfonic acid groups introduced into a lignin molecule Dy sulfite pretreatment contribute to the acceleration of the delignifi cation reaction Decause of their electron - - - - . witnurawing property KEY WORDS : PESULTS AND DISCUSSION In tne case of 12G C cooKing temperature , pulp yield decreased with increased cooking time , considerably during the initial oO minutes, and then levelled off. After the sulfite pretreatment , there was evidently a decrease in pulp yield as compared to the single stage cooking. As the cooking temper ature was increased to 160 C , pulp yield decreased significantly as compared to the former. Also, pulp yield differences between the two stage and the single stage cookings were getting closer at the final stage of cooking than at 120°C. As can be seen in Fig. 1 anc 2, the delignification rate is dependent on the cooking temprature and cooking time. Single stage alkali cooking shows 23.5 27.6% of low deligni fication rates. Two stage cooking resulted in delignification rate 2 times higher than that of single stage cooking , and differences of del g nification between two different cooking methods are seen to be maintained even after 120 min. cooking time. As the temperature is raised to lbO°C, the delignification rate at the initial stage showed relatively large differences (12 18%), but these differences gradually became smaller with increasing cooking time. In the case of single stage cooking , on the other hand , a continuous increase in the delignification rate was observed even after 18U min. cooking. 60 - - - ° - - - - Delignification , Two stage Cooking , - Single stage Cooking , Sulfite Pretreatment INTRODUCTION Pulping with soaium sulfite would appear to De tne most promising approach because the pH of these chemicals in aqueous media lies in the preferred range and sulfite ions have the ability to stabilize carbonyarates against the . peeling reaction However , sodium sulfite is very slow in its pulping action as compared to sodium bisulfite or kraft cooking liquor. Therefore , a two stage pulping method using sodium sulfite or sodium bisulfite in the first stage and another mild sulfide free pulping in tne second stage seems to De a promising - . - - - - - - process - - 3 * In the present paper , sodium bisulfite ana sodium sulfite cooking of beech wood meal to a high residual lignin content followed by a further delignification witn sodium hydroxide has oeen investigated. o EXPERIMENTAL o 3 3 50 c o O NaOH (3 N 1 H S O3 N a O H - CO 40 Na S 2 c 03 - N a O H Q © - Extractive free beech wood 30 o DY sodium bisulfite and sodium sulfite cooking liquors to be about du % pretreated yield. Sodium bisulfite cooking liquor was composed of y/L NaHSOj and 31.2 g/L Na C0 , and soaium 2 j B u i t i t e cooking liquot consisted of 30 g/L of Na Oj. ^ o meal was treated o 20 0 1 90 1 60 Cooking Fig. 1 - t i m e, 120 min Effect of two stage cooking on delignification of pulp ( 12 U C > . ° 43 of an increase in the acidity or tne a hydrogen according to the a sulfonate electron withdraw ing property. - - - - From the results of this experiment , tne effect of sulfite pretreatment in oxygen alkali cooKing is acknowledged to some extent on the staDilization of carbohydrates rather than on the acceleration of lignin dissolution. - CONCLUSION Two stage cooking results in a rapid - delignification rate within a comparatively - shorter time than single stage cooking , - Also, sodium sulfite alxali cooking shows a higher pulp yield with a lower lignin content than sodium bisulf 1 te alkali cooking because the former has many more sulfonic acid groups in pulp than in tne latter. - It is , therefore , concluded that sulfonic acid groups introduced into a lignin molecule by sulfite pretreatment contribute to the acceler ation of the delignification reaction because of their electron withdrawing property. - nif ication of pulp (at lt> OuC). Tne symbols correspond to tnose in Fig. i. - A comparison of the data described above with tnose listed in Table 1 shows clearly that the single stage cooking results in a relativ ely 'w and continuous increase in delignification e , wnile the two stage cooking shows a lower lignin content within a shorter cooking time . The authors (1) have proposed that sulfonic acid groups on the side chain of tne lignin molecule activate the alkaline degradation of aryl glycerol S aryl etner linkages, Relati ve to tne alkaline cleavage of B aryl ether link ages with an a sulfonate substituent , two alter native ways of the cleavage of B aryl ether structure (1 5) have been proposed: elimination of the a hydrogen , or elimination of the y hydrogen. Tne elimination of an a hydrogen is more possible than that of a hydrogen because - - - -- - - - - - ^- Table i. - REFERENCES 1. Aoyagi , T., Shimizu , H., Cho, N. S., Hosoya , S. and Nakano, J. Mokuzai Gakkaishi 24(8):558 562 (1978). - - 2. - Kratzl, K., Risnyovszky Schafer , E., Claus, P. and Wittman , E. Hoizforschung 20:21 27 (19 b6). - 3. Kratzl , K. and Spona, J. 20:27 30 ( l9 bo ). 4. Kratzl , K. 5. Ljunggren, S • r Ljungquist, P.O. and Wenger , U. Acta Chemica Scandinavica B 37:J 13 320 (1983). Holzforschung - - Paperi Puu li:o 51 (I9 bb). - - - - Cooking Results of Beech Wood Meal by SIR.gle stage and Two stage Cookings Cooking Method TS£5 - Compound - Single stage cooking > NaOH 120 160 12 U Oz - NaOH with MgCO} - Two stage NaHSOj COOKING - NaOH Na iSO3 " NaOH - ^0 NOTE: Total i NaOH 160 Time - . Yield (%) Lignin (% on wood) 120 9u 120 68.3 51.3 55.3 42.1 18.D9 4.65 7.58 2.93 88. bb .b 11.88 3.b 0 11.19 8u 0b 5 b . ob (min.) i 20 120 90 b2 lbO 120 90 90 lbO 120 90 90 49.6 61.3 48.0 b 5, 4 ** i th MgCOf run content in original wood meal is 25.83 %. 2.09 7.15 Dissolved Lignin ( *) 27.64 8 Z.U U 70.65 54.01 . 89.74 72.32 Funcal T r e a t m e n t o t E elftlJ ;u Phanero chaete c h r y s o s p o t i j m Burds ( M e- 446 ) was o b t a i n e d from the U.S. F o r e s t P r o d u c t s ^ DEGRADA TION OF CHLORIN ATED CIGNIN AND C H L O R I N A T E D ORGANIC S BY A WHITE ROT FUNGUS - Y. Matsum oto, C.F. Yin , H in. C n a n g , T.W. J o y c e D e p a r t m e n t ot wood and Paper S c i e n c e N o r t n Caroli na S t a t e U n i v e r s i t y at Raleigh - ana f.K. K i r k U.S. F o r e s t P r o d u c t s L a b o r a t o r y, Mauiso n, WI R o t a t i n g B i o l o g i c a l Contact or ( R B C ) treatme nt o t E effluen t troin a Kraft b l e a c h ^ - A n a l y s i s of t n e cnange total organic reveaieu cnlori ne ana in tne a m o u n t of inorganic RESULTS AND DISCUS SION T h e removal of o r g a n i c a l l y bound c h l o r i n e f r o m t h e EA ettluen t results in a d e c r e a s e i n t n e a m o u n t of T0C 1. chlonue :iat the c o n v e r s i o n of o r g a n i c c h l o r i n e inorga nic chlorid e r e s u l t s f r o m t n e d e g r a d a t i o n ot o t j a n i c chlori ne compoun ds in * ^ w n i t e r o t f u n g u s (P h a n e r o c n a e t e CNRYSOS PORIURN ; is shown t o b e e f f e c t i v e for t h e r e m o v a l o l o r g a n i c a l l y bouna c h l o r i n e as well as c o i o r. ^ decolor 1 z a t i o n ( and dechlor ination ) s t a g e , £ 1 effluen t w a s renewed every day. Treatm ent of E i n flask cultur es was a l s o perform ed a c c o r d i n g t o previou sly publish ed procedu res ( 4 ). E v e r y two d a y s, t h e c o n t e n t s of three t l a s K s were analyse d . ABSTRA CT p l a n t with L a b o r a t o r y ana was c u l t u r e d in R o u x bottles t o obtain tne conidia l inoculu m. Fungal t r e a t m e n t ot E oy tne R B C w a s perform ed a c c o r d i n g t o previou sly p u b l i s h e d p r o c e d u r e s ( 4 ). During t h e oijanicall It t n e r e m o v a l ot bound chlorin e is based on the organic chlorin e i n t o inorgan ic into c o n v e r s i o n of e L 11 u e n t c h l o r i d e, an i n c r e a s e i n i n o r g a n i c c h l o r i d e as well a s a d e c r e a s e in o r g a n i c c h l o r i n e should oe . o b s e r v e d. INTROD UCTION S i n c e t n e late 1970's, N o r t h C a r o l i n a State U n i v e r s i t y and the U.S.D.A.'s Forest P r o d u c t s L d u o c d t o r y (H a a i s o n ) h a v e j o i n t l y studied the applica tion o t t h e l i g n i n degradi ng ability o t w n i t e- r o t f u n g i t o t n e removal of c o l o r from E eftlue nt During this s t u d y, H u y n h and c o- . • ^ t u n g u s in the same manner a s lignin or lignin . compounds The similarity of lignin degradation mechanisms to tne aenalogenation r e a c t i o n s K n o w n t o b e used oy some o t h e r m i c r o o r g a n i s m s ( 2 ) c r e a t e d an i n t e r e s t t o l e a r n more or t h e ability of w n i t e- r o t fungi t o oegraae cniorin atea o r g a n i c c o m p o u n d s, present The r e p o r t deals w i t h the convers ion of o r g a n i c a l l y bound chlorin e oy f u n g a l t r e a t m e n t s t a g e effluen t. oi . ^ w o r k e r s ( 1 ) showed that Chlorin ated phenoli c c o m p o u n d s can oe modifie d or d e g r a d e d by t h e mooex T o ev uate the ability ot w h i t e rot t u n g i t o remove : > ganica lly bound cnlorin e rom chlorin ated o r g a n i c c o m p o u n d s , tne low molecui cr w e i g h t fracti on of E ( MW < 1000 ) , high molecul ar w e i g h t fracti on o t £ (MW > 1 0 0 0), and untract ionated E ^ were suoject ed t o fungal t r e a t m e n t using the RBC. Figure 1 snows tne results for one day treatme nt u s i n g the R B C over t n r e e succes sive d a y s. T n e r e m o v a l o t o r g a n i c chlorin e is clearly shown with an a v e r a g e removal r a t e of t> 2 % , 43 %, a n d 45 % t o r l o w m o l e c u l a r w e i g h t E , nigh molecul ar weight E , ± a n d untract ionated E , r e s p e c t i v e l y. I n o r g a n i c c h i o r i a e as w e l l a s low molecul ar w e i g h t chlorin ated c o m p o u n d s ace t h o u g h t to p e n e t r a t e i n t o t n e fungal ceil; a p o r t i o n o t them may b e e x c r e t e d , w m l e some may r e m a i n inside t h e cell. T n i s will cause a c h a n g e in t h e measure d ^ ^ a m o u n t o t t o t a l chlorin e. Actuall y , in these e x p e r i m e n t s, the a m o u n t of total chlorin e (T C l j EXPERI MENTAL, Measurement Species oi w a s o c c a s i o n a l l y observe d to c h a n g e signifi cantly b e t o r e and a f t e r R B C t r e a t m e n t . A l t h o u g h tne removal ot organic ally bound c h l o r i d e f r o m E by RBC treatme nt was observe d , t h e C o n c e n t r a t i o n of Chlorin e - The S c n o m g e r c o m b u s t i o n metnou was used total chlori ne (TCI ) for ^ t h e m e a s u r e m e n t of employi ng a chlorid e s p e c i f i c electro de. the mechani sm for t h e removal ot o r g a n i c chlorine remained uncertain T o clarity t n e m e c n a n i s m for the r e m o v a l o t o r g a n i c c h l o r i n e , the p e n e t r a t i o n and e x c r e t i o n - o t c h l o r i n e s p e c i e s i n t o t h e t u n g a i ceil had t o be evaluat ed. T o t h i s end , t u n g a i treatme nt ot a c c o r d i n g t o the p r o c e d u r e d e v e l o p e d by S j o s t r o m . Inorgan ic chlorid e ( IOC1) was measure d by ( 3) Total o r g a n i c c n i o r m e ( TOCl ) was calcula ted b y subtra cting loci t r o m T C i: ( Toci « rci loci ) . . EL was p e r f o r m e d i n an Erlenme yer tiask w i t n o u t c h a n g i n g ettluen t t n r o u g h o u t t h e t u n g a i g r o w t n 45 and dechlorination stages (Figure 2). Thus, it is clearly snown that a decrease in the total organic chlorine is accompanied by Unfractionated 0.1 6 an increase E1 . Because of tne inorganic cnloride 0.10 netration ot inorganic chloride into the t. fungai cell, the amount of total chlorine decreased in the first six days. After six 05 days, however , when a rapid increase in tne amount of inorganic cnloride was observed , the o O amount ot total cnlorme gradually increased almost to the original level. The possibility still can not be excluaea , however , that the accum ulati on of chlor inate d organ ic compou nds in j . 0 Fig. 1 o The formation ot volatile chlorinatea in treatment was not evaluated < cr O . . Evans, B.S.W. Smith , H.N. Fernley , ana J.I. Davis, biochem. J • » 122:543 (1971). LU d C . H. Eriksson ana L. sjostrom , Svensk cr Papper ;tidn , 79(17)::> 7U ( 197 b) O . и ,(j, j Eaton , H m. Chang , T.W. Joyce ana T K. Kir *, TAPP I , b 3( 10 ):103 ( 1980 ) . - ' . ( > 1 0 0 0) fraction II 5 4 6 7 Total c hlorIne (TCI ) \ 1 36 34 Inorganic I I 33 chloride I- (IOCI) 31 4 3 i I Total organic ^ cl l o r l n # ( TOCI) 2 X O . к. Sruma da , Mokuza i CaKKd ishi , 28: 376 (1982) . 7 o Kirk , TAPPI , in press. j 5. High Mw 6 LU . V-a. Huynh , h-m. Chang , T.w. Joyce , and T.K. . E O 1 4 5 32 REFE RENC ES 2. 4 Removal ot organic chlorine from efrluent by RBC treatment. 36 h this experiment. <1000) 37 reaction compounds by fungal ( fraction TIME (days) 2 . 7 0.05 ^ - 6 O 0.10 e eftluent. As an example for biological oxidation , oxidative ring opening of z,4 D (2,4 alcnlorophenoxy acetic acid ) catalyzed by some enzyme system ( ) 2 is known to ue followed by a aechlorination - Mw CT - chlorine from E n 0 < 0.15 . organic Low O cnlonae is completely an enzymatically catalyzed process. It should be noted , howev er , that tne lignin degradation reactions known for this fungus oxidation of side cnains and — 5 0.05 - o it is still unknown whether or not tne conversion of organic cniorme into inorganic would assist in chlorine elimination as r * iorid e Some examples are known tor the irine elimination reaction combined with oxiddtion reactions Shimada (5) snowed that a photo oxidative treatment can effectivel y remov 4 X It can be concluded , thougn , that a major portion of tne organically bound cnlor me is converted into inorganic chloride by fungal treatment. of tne aromatic moiety {l ± 0.10 cr o _ cniorine. oxiuative cleavage o LU trie Lungal Dody also contri butes, to some exten t , to tne removal of organ icall y uounu — 0.05 1 0 2 4 6 TIME ( days ) 6 10 . 2 Formation of inorganic chloride auring Fig fungal treatment. 16 CATABOLIC SYSTEM COMPOUN DS BY OF L I G N I N -RELATED MODEL P S E U D O M O N A S S P. T M Y 1 0 0 9 S T R A I N 1 Masahir o Same]ima Yoshimas a S a b u r i *1 *2 Tomotak a Y o s h i m o t o T e r u k o Nakazawa *3 and T o s h i o Fukuzumi D e p a r t m e n t of Forest Products , F a c u l t y o f A g r i c u l t u r e , U n i v e r s i t y of T o k y o * 2 School o f Allied Health S c i e n c e s , Yamaguch i b N - methyl - N'- n i t r o - nitrosog uanidine m u t a g e n e - followe d by penicil lin - cyclose rine screen m g i n t h e M 9 medium c o n t a i n i n g 0.2 % of DDVA ( I ). Four differe nt t y p e s of m u t a n t s on dissimi l a t i n g a b i l i t i e s were obtaine d. Table 1 D ^ s s i m i l a t i n g abiliti es of TMY 1009 and derived m u t a n t s Strain Substrate s i: T M Y 1 0 0 9 ( wiId ) University T M Y 1014 * 3 D e p a r t m e n t of TMY 1015 Forest Product s , F a c u l t y of Agricul u r e, T o k y o Universi ty of Agricult ure and Technology ABSTRACT DDVA Ver A VA PA - 44 - 4- 4- 44 44 4 44 44 44 44 4 TMY 1 0 1 7 4 TMY 1018 4 :comp letely dissimi lated lated , 4 44 : partialy dissimi - not dissimi lated A bacteri al strain TMY 1009 , which w a s able t o d e g r a d e m a n y t y p e s of lignin model compoun ds, were isolate d. From the results of catabol ic e x p e r i m e n t s by mutants of TMY 1009 , it w a s sug g e s t e d that t h r e e differe nt t y p e s of O-d e m e t h y l a t i n g s y s t e m and t w o differe nt t y p e s of r i n g c l e a v i n g s y s t e m are related t o the catabol ism of lignin model c o m p o u n d s by TMY 1 0 0 9. KEYWORDS:Pseudom onas , L i g n i n model c o m p o u n d s , Mutant , Biodegra dation INTRODUCTION Kecenciy , it have been confirm ed t h a t some bacteri al s t r a i n s are able t o d e g r a d e lignin related polymers such a s DHP and MWL ( Crawford , 1981 ; Kern , 1984 ). However , the mechansi m of bactera il degradat ion of lignin related compound have never been i n v e s t i g a t e d in detail. We have isolate d a n e w bacteri al strain T M Y 1009 . frorr FK - 2 c u l t u r e ( Fukuzumi , 1 9 7 7 ), which is able to Uegrade complete ly many tyoes o f lignin model compoun ds w i t h m a j o r inter 1 i n k a g e s of t h e C6 C, » n i t i n lignin. T h i s bacteriu m is confirm ed Lc oe a closely similar s t r a i n t o Pseudom onas * rimooi 1 is by t h e cell form and physiol ogical charact eristic s * We have started to i n v e s t i g a t e f l a i l e d catabol ic mechani sm of l i g n i n rela ted c o m p o u n d s by TMY 1009 , and t o determi ne t h e catabol ic s y s t e m s and pathways of monomer ic and dimeric lignin model c o m p o u n d s , catabol ic e x periments part by deficie nt mutnats o f TMY 1009 o n a of t h e c a t a b o l i c s y s t e m s have been under - DISSIMI LATION O F DERIVER TIVES O F BENZOIC Ar D TMY 1009 i s able t o dissimi late complete!/ all of DDVA ( I ) , VerA ( II ) , VA ( III ) , and PA ( IV ), w h e r e a s mutant s t r a i n s a r e unable t o d e g r a d e a part of these c o m p o u n d s. TMY 1014 is u n a b l e t o d e g r a d e entirely DDVA ( I ). However , this mutant c a n dissimi late com pletely VerA ( II ) , VA ( III ) , and PA ( IV ). TMY 1015 is also able t o dissimi late c o m p l e t e ly VerA ( II ), VA ( III ), and PA( IV ). Furtherm ore , this mutant convert s DDVA ( I ) t o 5 -( 2 ' - hydroxy 3 ' - methoxy - 5'- carboxy 1 - pheny 1 ) - vanilli c acid ( V ) • T h e r e f o r e, TMY 1015 might be deficie nt o n the n n g - c i e a v m g s y s t e m of c o m p o u n d ( V ). O n the other hand , TMY 1014 might be deficie nt on O - d e methylat ing s y s t e m of DDVA ( I ) t o compound ( V ). TMY 1017 can ' t d e g r a d e entirely PA ( IV ). How ever , t h i s mutant i s able t o c o n v e r t both VerA ( II ) and VA( III ) t o PA ( IV ). Therefo re , t h i s m u tant lacks r i n g - c l e a v i n g s y s t e m of ^' fTV ). T M Y 1 0 1 8 c a n ’ t d e g r a d e entirely VA ( III ). How ever / t h i s m u t a n t dissimi lates complet ely PA ( IV ) and convert s VerA ( II ) t o VA ( III ). Therefo re , t h i s m u t a n t 125 def lcienfc O -d e m e t h y lat i n g s y s t e m ' ( OOII . coon ( OOII H CO Oil taken. OH (I) ( PREPARA TION O E M U T A N T S ( 0011 (U) OOII ( rii ) COOH (O O I I OH OH . Mul n t s t r a i n s of Pseudomo nas s p TMY 1009 , which are unable to grow on the M 9 - a g a r plate c o n t a i n i n g 0 . 2 » of dehydro divani 11 i c acid ( DD V A :I ) a s a s e source of carbon , were p r e p a r e d I I ,( O OH ( iV ) OH (V) 47 t o VA( IXI )• RELATIONSHIP VA(IJI O F CATABOLISM BETWEEN D D V A( I ) A N D ( III ), ^ TMY 1014 and TMY 1015 are deficient on earier DDVA I . However , these ca tabolic deficiency dose not affect on the catabolism of VA ( III ) which is dissimilated completely in these mutants as same in the case of the wild strain(TMY 1009 ). Therefore , the catabolism of VA ( III ) is considered to be mdependant from the catabolism of DDVA ( I ). steps of ( ) # A ' ¥ I : ! O n the other hand , the catabolic d e f i c i e n c y of VA ( III ) in either TMY 1 0 1 7 or TMY 1018 cause to repress the initiation of catabolism of DDVA ( I ). Although it is difficult to explain the reason of t h i s phenomenon, the catabolic s y s t e m of VA ( III ) m i g h t be related t o the latter catabolic s t e p s of DDVA ( I ) and affect t h e initiation of catabolism of DDVA ( I ). These idea were further supported from the results of induction e x p e r i m e n t s by TMY 1009 as shown i n Table 2. Table 2 T h e second system i s 4 - O - demethylating system of VerA ( II ). It i s q u i t e different s y s t e m from t h e third s y s t e m , 3 -0- demethylating s y s t e m of VA Results of induction e x p e r i m e n t s in TMY 1009 Inducer DDVA VA Catabolism of DDVA VA 4 because TMY 1 0 1 8, which i s deficient 3 -0demethylating s y s t e m , can still convert VerA ( II ) to VA ( III ). R I N G -CLEAVING SYSTEM Two different t y p e s of r i n g -c l e a v i n g s y s t e m a r e related t o t h e catabolism of l i g n i n model c o m p o u n d s by TMY 1009. T h e first o n e i s the r l n g - c l e a v m g s y s t e m of c o m p o u n d ( V ). This s y s t e m i s clearly d i s t i n g - uished from t h e another r i n g - cleaving s y s t e m of PA ( IV ) because TMY 1 0 1 5 , which is deficient in t h e r i n g - cleaving system o f c o m p o u n d ( V ), c a n d e g r a d e PA ( IV ) a s same a s t h e wild s t r a i n ( TMY 1009 ). CONCLUDING REMARKS From the catabolic e x p e r i m e n t by m u t a n t st rains derived from TMY 1009, it i s suggested that TMY 1009 has three different t y p e s of O -d e m e t h y lating s y s t e m and two different t y p e s of n n g cleaving s y s t e m o n the catabolism of lignin m odel c o m p o u n d s. However , further i n v e s t i g a t i o n s o n e n z y m i c levels will be required for final determination of these s y s t e m s. 4 f REFERENCES None induced , not induced DDVA ( I ) induced both of catabolisms of DDVA ( I ) and VA ( III ). However , VA ( III ) dose not in - duce the catabolism of DDVA ( I ). T h e s e observa t i o n also s u g g e s t e d that t h e catabolism of VA ( III ) is independant frem the catabolism of DDVA ( I )« O n t h e other hand , t h e catabolism of DDVA ( 1 ) i s closely related t o t h e catabolism of VA ( III ). O DEMETHYLATING SYSTEM Three different types of O - demethylating s y s f r * m might o e related to the catabolism of lignin model c o m p o u n d s by TMY 1009. The ilrst one i s O- demethylating system of DD . A ( I ) t o convert t o c o m p o u n d ( V ). T h i s s y s t e m be 11 stinguished from both 4 - O - d e m e t h y l a t Ing s y s t e m of VerA ( 11 ) and 3 - O demethylating s y s t e m of VA ( III ) , because TMY 1 0 1 4 , which is de ficient on O demethylating s y s t e m of DDVA ( I ), * abl » - - f 7 DEALJJE completely both of VerA ( II ) . d VA( I 11 ) 48 Crawford , R. L.:L i g n i n b i o d e g r a d a t i o n and t rans - formation , Wiley and S o n s , pp.55 - 6 0 ( 1981 ) Fukuzu.ni, T., Katayama , Y.: Mokuza l Gakka I shi , 23 , 7.14 - 215 M 9 7 7 ) Kern , H , W.,: Arch. Microbiol., 138, 1 8 - 25( 1984 ) , C NMRof Lignocellulosics 3 13 C CP / MAS SPRUCE WOOD M. G. Taylor and R. H. Marchess ault Xerox Research Centre of Canada 2660 Speakman Drive Mississau ga, Ontario Canad.i L5K 21 “ Exploded " vw A High resolution nC NMR of crystalline celluloses is both compleme ntary and suppleme ntary to x * ray diffraction analysis because it is effective for both crystalline and non -crystalline materials Good spectral quality has been achieved for a range of cellulose samples and spectral elements related to lateral order are observed but interpreta tional details are still evolving. . Interrupted Decouplin g B The spectrum of a complex material such as wood, shows morpholo gical and conformat ional features for each chemical component The resolution achiev d is sufficient to allow identificat ion of carbohydr ate resonance s, methoxyl and aromatic resonance s and carbonyl resonance s of hemicellu lose acetyls as shown below in Figu e 1 Difference A -E . 200 * 100 0 PPM . , Figure 2 3C CP MAS NMR spectra of ’exploded’ spruce wood. Spectrum A is the normal spectrum, while spectrum B was obtained using the interrupte d decouplin g technique . A 4x Figure I, !3C NMR of solid ash wood B The effect of solid state chemical treatments such as acetylatio n and prehydroly sis are readily detected The use of interrupte d decouplin g allows one to separate some of the lignin and carbohydr ate components in the spectra, This technique is illustrate d in Figure 2. . C he potential of the technique for rapid C analysis of paper and '* * ther composite s is now becoming well - establishe d. More complex biosubst ances such grasses, bark and plant cell wall being roolecula rly examined in their for the first time. this paper series of presented covering various f > as are true nascent state , a spectra are Physical states of Ksparto grass: native, holocellul ose, alkali extracted and pulp. These spectra are shown in Figure 3 . -D 200 150 100 PPM 50 I 0 . Figure 3 C PM AS NMR spectra of Esparto grass derived samples Spectrum A correspon ds to the native material after ethanol/ benzene washing Spectrum R is chlorite holocellu lose. Spectrum C is holocellul ose extracted with FV NaOH. Spectrum I) is a commerci al FspRrto grass pulp. . . The xylnn component extracted form the grass is also examined in dry and hydrated states ( cf. Figure 4.1 . 49 HYDR ATED T 100 PPM . 50 , 3C CP/M AS NMR spectra Figure 4 of Esparto grass xylan correspo nding to the "dry *' and "hydrated" polymorp hs . The line broaden ing effect of the latter on the C - l resonanc e of the cellulose, as illustrate d in Figure 5 demonst rates the difficulty in interpret ing the effects of fine structure vs. heteroco mpositio n . HOLOC ELLUL OSE HYDRA TED XYLAN 1C 0 PPM 50 » ft , Figure 5. 3 C CP / MAS NMR spectra of Esparto grass holocellu lose and hydrated xylan . r» I | starts fror the lumen by lysing the transition zone between S and S , without any degradation of S • As a result is detached from S . T*en 2 S undergoes important damages ( bore holes) be 2 fore being split from S which is degraded later. 1 The most resistant parts are the cell corners. ULTRASTRUCTURAL MODIFICATIONS OF WOOD AFTER DEGRADATION BY SPOROTRICHUM PULVERULENTUM AND ^ ITS MUTANTS - JEAN PAUL JOSELEAU and KATIA RUEL - - C.E. R.M.A.V. C.N. R.S. GRENOBLE B.P. 68 38402 ST MARTIN D 1 HERES CEDEX FRANCE - The pattern of propagation observed with the mutants which lack cellulase activity differs in that no large holes are visible in the wall. Instead a loose "treillis " is apparent in S . In order to characterize the exact nature of this undegraded material the specific markers were applied. It could then be demonstrated that even at the level of the thinnest fibrillar elements , glucomannans and xylans were still present. As shown by shadowing and by " low dose" observation the fibrillar network was identified as primarily constituted of cellulose. Although the moc fied fungus strain was reported to be cellulase- less , it is clear from the electron diffraction dia gram that the fibrillar material lost most of its characteristic crystallinity. These images are interpreted in terms of ultrastructural relationship between cellulose hemicellulose and lignin at the microfibrillar level. ^ KEYWORDS : Wood ultrastructure, white rot fungus cellulose hemicellulose lignin associations. - - Modifications of the ultrastructure of sam ples of spruce wood which had been submitted to the action of the white rot Sporotrichum pulve rulentum and two of its mutants were studied by electron microscopy. Comparison of the images observed on the undegraded wood , the wild type and the cellulase less mutant degraded wood provided information on the mode of action of t ) e fungus but also on the distribution and as sociation of cellulose , hemicellulose and lignin at the microfibrillar level. Wood degradation by white rat fungi involves the combined action of lignin degrading enzymes and polysaccharide degrading enzymes. The enzymic equipment of Sporotrichum pulverulentum and of some of its mutants has been studied by Eriksson et al ( 1 ). The ultrastructural modifications re sulting from the fungus action has been shown to be mainly located in the S layer ( 2). In order 2 to study the proper action of each of the dif ferent enzymes acting on the main polysaccharide constituents of the wood , we used two genetic mutant strains lacking cellulase activity , and a catabolically repressed strain having lost its cellulase and hemicellulase activities. In order to visualize the removal or degradation of the different cell wall polymers , specific markers were used. Lignin was stained by permanqanate and the hem tee 1 luloses were identified by two newly developed techniques. Both techniques involve the use of a purified enzyme correspon ding to the polysaccharide to be identified. In the first one , enzyme gold complexes were pre pared ( 3) and were applied to the ultra thin sections. In the second , a slight enzymic hydro lysis of the polysaccharide substrate was per formed directly on the ultra thin section follo wed by silver st aining of the newly created reducing ends ( 4). - - - - REFERENCES 1. ERIKSSON , K .r • * GRUNEWALD , A. and VALLANDER , L. Studies of growth conditions in wood for three white rot fungi and their cellu lase less mutants. Biotechnol. Bioeng. XXII: 363 376 ( 1980). - - 2. - - - - RUEL, K. and BARNOUD , F. Ultrastructural aspects of wood degradation by Sporotrichum pulverulentum. Observation*"spruce wood impregnated with glucose. Holzforschung 38( 2): 61 68 ( 1 984). - 3. RUEL , K. and JOSELEAU , J.P. Use of enzyme gold complexes for the ultrastructural lo calization of hemicelluloses in the plant cell wall. Histochem. 81: 573 580 ( 1984). 4. JOSELEAU , J.P. and RUEL, K. A new cytoche mical method for ultrastructural localiza tion of polysaccharides. Biol. Cell. 53: 61 66 ( 1985). -- - -- - - - - - - - - - From the imaaes obtained with the wild type strain , it a p p e n d that the fungal degradation 51 RESUL TS CHARA CTERI SATIO N O F LIGNI N STRUC TURES IN W H O L E WOOD BY C A R B O N - 13 CP / MAS NUCLE AR MAGNE TIC RESON ANCE Tho broke n line in F i q. 1 marks a comrr.cr basel ine for both curve s. R H NEWMA N , K R MORGA N and G J LEARY C H E M I S T R Y DIVIS ION , DSIR PRIVA TE BAG , PETON E NEW ZEALA ND ABSTRACT s p i n - locki ng pulse sequ . i c e has been c o m b i n e d with digit al resol u '. on e n h a n c e m e n t t o impro ve detai ls in solid - stai NMR s o e c t r a o f wood. T h e proce dure has pro :; d e s t i m a t e s of syrin gyl / guaia cvl ratio s, * . o exten t o f B O 4 - ether ifica tion and ligni n / tar i n ratio s for sever al hardw oods and softw o :s. A * * 160 * 150 MO 130 PPM Figure 1 . - Carbo n - 13 CP / MAS NMR s p e c t r a o f P i n u s r a d i a t a wood: ( A ) norma l s p e c t r u m , ( B ) with s p i n locki na and resol ution enhan cemen t. C- l C- 3 C 4 - C- 5 Se 134 153.4 Sf 137 133 147.8 138 153.4 147.8 INTRO DUCTI ON Ge 134 148.4 152.7 Gf Carbo n - 13 C P / MAS NMR s p e c t r o s c o p y allow s chara cteri satio n of ligni n in solid wood , 133 148 He unit KEYWO RDS: . Nucle ar m a g n e t i c r e s o n a n c e, ligni n . tannin avoid ing t h e risk of chemi cal m o d i f i c a t i o n that a c c o m p a n i e s extra ction. Ligni n signa ls form an almos t conti nuous band from the cellu lose signa ls t o about 155 ppm. W e have tried t o resol ve this conti nuity by using a s p i n - locki ng pulse s e o u e nce t o e x t r a c t speci fic s i g n a l s from t h e band . This invol ves inser tion of a delay ( T ) betwe en cross p o l a r i s a t i o n and data acqui sitio n. T h e carbo n t r a n s m i t t e r power is adjus ted t o spin lock m a g n e t i s a t i o n from non - p r o t o n a t e d carbo n , methy l and motho xyl group s. Signa ls from rigid CH and CH group s d o not survi ve this treat ment , 2 becau se o f s t r o n g C- H dipol e - dipol e inter actio ns. - EXPE RIME NTAL Wood c h i p s were packe d i n a Kel - F r o t o r and spun a t 2.5 kHz in the m a g i c- a n g l e spinn ing probe of a V a r i a n XL - 2 0 0 s p e c t r o m e t e r , for NMR at 50.3 MHz. Each 1 m s c o n t a c t time was follo wed by t h e delay T , 2 0 ms of data acaui sitio n , and a delay o f at least 0.2 s t o allow for recov ery of t h e p r o t o n m a g n e t i s a t i o n. Betwe en 3 x 10 4 and 2 x 10 ^ t r a n s i e n t s were avera oed . A nomin al value f x = l ms was used for r o u t i n e s p e c t r ° a. Eore ntz i a n - t. o-Gauss l a n t r a n s f o r m a t i o n s w e r e used for resol ution enhan cemen t ( 1 ). H * Table 1 . 145.5 163 > * 4 158 Chemi cal shift s ( ppm from T M S ) avera ged over sever al sampl es. S ,G and H u n i t s Relat ive contr ibuti ons from syrin gyl ( S ) , guaia cyl ( G ) and p- hydro xyphe nyl ( H ) u n i t s can be estim ated from the s p e c t r a b y: ( a ) m e a s u r i n g the ratio o f signa l areas a s s i q n e d t o metfo xvl and a r o m a t i c c a r b o n , or ( b ) c o m p u t e r simul ation o f the r e g i o n from 125 t o 165 ppm. T h e r esults from metho d ( a ) show a s t r o n g depen dence on T , a n d m u s t be extra polat ed back t o T = 0. Both metho ds m u s t inclu de c o r r e c t i o n s for i n t e n s i t y lost in spinn ing s i d e b a n d s. Metho ds ( a ) and ( b ) g a v e S / G = 5 and S / G = 4 ( respe ctive ly ) for wood from Eucal yptus renna ns. Bland ( 2 ) found S / G = 3.7- 4.4 for wood from the same s p e c i e s , based on nitro benze ne oxida tion. Metho d ( b ) g a v e S /G = 0 . 5 for wood from P s e u d owinte ra colo rata ( fin . 2 ) . T h i s i s unusu ally low for a hardw ood , but c o n s i s t e n t with oubli shed value s of 0.53 ( bv acido lysis ) and 0.56 ( by per m a n g a n a t e oxida tion ) for wood from the same s p e c i e s ( 3 ). O u r resul ts there fore s u p p o r t the r e l i a b i l i t y o f chemi cal p r o c e d u r e s for estim ation of S / G . - 53 I A spectrum of a softwood showed a weak signal assigned to H un.ts (Fig . 3B). Spectra of two monocotyledons (bamboo and Cordyline australis) showed only signals from G and S units. 160 150 140 130 PPM Figure 4. 160 150 140 130 PPM - Carbon 13 CP / MAS NMR spectra of Pseudowintera colorata wood. - Carbon 13 CP / MAS NMR spectra of (A ) pohutukawa wood ( Metrosideros excelsa ) , ( B ) tannin extracted with acetone /water at 20°C. REFERENCES 1. FERRIGE , A .G. and LINDON , J.C. Resolution enhancement in FT NMR through the use of a double exponential function. J. Mag. Reson. 31( 2): 337 340 (1978). 2. BLAND , D.E . , HO , G. and COHEN , W.E. Aromatic aldehydes from the oxidation of some Australian woods and their chromatographic separation. Aust. J . Sci. Res. , Ser. A 3(4): 642 648 ( 1950). 3. SHIO , T. and HIGUCHI , T. Studies on the lignins of Podocarpus , Gnetum , Drimys and Pseudowintera. Wood Research 63:1 10 ( 1978). - - 160 150 140 130 PPM Figure 3. - Carbon 13 CP / MAS NMR s •ctrum of wood from two rimu (Dac ^ydium cupressinum ) trees. • Etherification Structures with B 0 4 ether linkages are labelled Sc , Ge and He in Table 1. Structures lacking this linkage are labelled , and Fig. 3 shows that the extent of etherification can vary from sample to sample , even within a species. -- Sf Gf Lignin / tannin ratios Condensed tannins contribute signals at 145 and 155 ppm. In the case of pohutukawa wood ( fig. 4) , simulation of the NMR spectrun aave a lignin tannin ratio of 2.5 (by weight ). : ome of the tannin was extracted by refluxing ethanol , but most ended up in Klason " lignin ". In our /eys of Eucalyptus and Nothofagus species we found particularly low 1 ignin / tannii ratios for E. botryoides and N. fusca. - 54 - A screening of isolates fran various culture colleen xons indicated that there were sene rviturally curring strains of cellulolyt.c fungi which appeared to fc*. as hydrolytic as the various Trichoderma reesei mutants used by other groups. We compared the various enzyme activities of T. reesei C30 with one of the strains fran our culture collection, T. harzianum E58, which was known to be highly hydrolytic. T. reesei C30 produced considerably more extracellular FNZYMATIC HYDROLYSIS OF PRETFfT TED WOOD TO FERMENTABLE SUGARS USING CELLLTASES FRO. TPICHODEFMA HARZIANUM 4 * J.N. SADDLER, C. BREUIL, M. MES HARTREE, L. TAN AND E.K.C. YU - FORINTEK CANADA CORP. 900 MONTREAL ROAD OTTAWA , ONTARIO KlG 3Z5 ABSTRACT During the last six years the Biotechnology and Chemistry program at Forintek has looked at the overall process of converting wood residues into higher value products. Initially a variety of chsnicol methods of hydrolysis including hydrofluoric acid and organosolv were compared with various enzymatic hydrolysis methods associated with different pretreatment procedures. A preliminary eccncmic study indicated that all of the three major wood components, i.e. lignin, hemicellulose and cellulose have to be used if the conversion of wood to fermentable sugars is to beccme a ccrmercially viable process. Steam pretreatment proved to be an excellent method for fractionating wood into its three components as well as considerably enhancing the efficiency of enzymatic hydrolysis. In all of the processes which hope to produce ethanol and other liquid fuels from wood residues using enzymatic hydrolysis the most expensive step has been shown to be the production of the cellulase enzymes. It is this requirement for an active cellulase ccmplex acting at optimum conditions on a wide range of cellulosic substrates which has severely curtailed the application of bio conversion processes based on enzymatic hydrolysis. The wood decay fungi have proven to be among the most cellu lolytic organisms with relatively few cellulolytic bacteria so far identified. A ccmparison of cellulolytic fungi and bacteria isolated on field trips and available from culture collections indicated that fungi were generally 100 1000 times more hydrolytic than the most active cellulolytic bacteria. This higher activity was mostly due to the greater amount of extracellular protein secreted by the fungi. Most of the bacteria secreted an inccmplete Cellulase canplex which could only hydrolyse highly modified substrates such as filter paper and carboxymethyl cellulose. When the overall hydrolytic activity of the fungal and bacterial systems were conpared it was fourri Uiat the majority of the oanplexes were deficient in one or more of the endoglucanase, exoglucanase or B glucosidase components. Af >art frem the deficiencies that were apparent m the methods for assaying for individual and collective cellulase activities, other factors such as the half life of the enzymes, enzyme regulation, growth of the organism , etc., all significantly affect the way in which the hydrolytic potential of the various microorganisms could ho measured. - - protein indicating that the high hydrolytic activity of the cult ire filtrates was probably due to more enzynv * beini present. When the culture filtrates from the tvo funci were used to hydrolyze a range of pretreated wood substrates comparable reducing sugar values ware obtained. There was a major difference hewever in the proportion of glucose that was obtained. The higher B glucosidase activity of T. harziar. m culture filtrates was ref lected by the fact that the majority of the sugar was detected at glucose. Although we wore ahLe to increase the efficier, of hydrolysis canparod to that achieved with seme of the earlier T. reesei mutants we have not been able to substantially increase the specific activity of the celiulases. The term specific activity is used here to mean the amount of extracellular protein required to hydrolyse a stated amount of cellu jse. Previous attempts at increasing the efficiency of cellulose hydrolysis have primarily concerned themselves with increasing the productivity of the strains or at increasing the amount of extracellular protein. Although these higher values have significantly increased the efficiency of hydrolysis it is unlikely that these very high levels of extracellular protein can be increased much more than the levels of approximately 40 mg/mL reported by seme workers. It is apparent that before enzymatic hydrolysis of cellulose to glucose can be expected to be competitive with other sources of sugar it is important that we fully understand the nature of the synergistic action of cellulase hydrolysis and , more importantly , substantially increase the specific activity of the cellulase enzymes. - • - - - 55 been used to study chip impregnation with sodium STUDIES OF THE IMPREGNATION OF BIRCH USING SCAN - NING ELECTRON MICROSCOPY AND ENERGY DISPERSIVE X - RAY ANALYSIS sulphite in the production of CMP [7]. Alt ough these methods can be used to study chip irnreg nation or, a macroscopic scale , they cannot be used to determine the distribution of chemicals in the various morphological regions of wood . G. Bengtsson 1 , R. Simonsson 2 , C. Heitner 3 , R.P. Beatson 3 and C. A. Ferguson 3 transmission electron microscopy have been used to study the anatomy and morphology of wood [8, 9], and in combination with energy dispersive x- ray analysis have bee Scanning 1 EKA AB, Surte, Sweden 2 Chalmers University of Technology , Goteborg , Sweden 3 Pulp and Paper Research Institute of Canada , Quebec, Canada used to determine the distribution of chemicals in t) e different morphological regions of wood [ 10, 11 ] ABSTRACT method of determining the amo r; t of sodium sulphite at any given position in a wood sample has been developed , Birch woou was impregnated with 6odium sulphite under varying conditions. The amount of sodium and sulphur A that enters the wood longitudinally was measured different distances from the ends of the samples with a scanning electron microscope equipped for energy dispersive x - ray analysis. The sulphur content was determined as a function of the distance from the ends for the various at . morphological regions The distribution of sodium and sulphur by thi 3 method of analysis showed good correlation to those obtained for sulphur by ion chromatography and for sodium by atomic absorp obtained tion spectroscopy. and . aim this study has been to develop a method of determining the distribution of chemicals such as sodium sulphite in wood chips as a function of distance of penetration , as well as the relative distribution of chemi cals in the various types of cells in wood . The of EXPERIMENTAL impregnation experiments were c - ned out on sawn samples of white birch , l tula papyrifera with dimensions 30 x 10 x 7 mm in the axial , tangential and radial directions respec tively , as shown in Figure 1. The samples were steamed at 100°C for either 10 or 15 minutes and immediately immersed into 126 g/ L sodium sul phite solution for 15 minutes at room tempera The *• • INTRODUCTION Chemithermomechanic al pulps, CTMP produced from chips that have been given a mild treatment with sodium sulphite are being used in fluff , tissue and paperboard products [ 1 ] , whereas chemimechanical pulps, CMP produced from chips treated with sodium sulphite to high sulphonate content are used as a reinforcement component in newsprint [ 2 ]. The development of desirable strength and optical properties of CTMP and CMP 10mm requires good impregnation and distribution of sodium sulphite solution in the wood chips prior to sulphonation and subsequent disc refining . Poorly impregnated chips will contain a signifi cant a TANGENTIAL 10 mm RADIAL 7 mm amount of untreated wood which can produce AXIAL 3 0 mm pulp containing large proportion of stiff , shortened fibres that form weak interfibre bonds Since sodium sulphite is a mild bleach ing agent , poor impregnation can also cause low . pulp brightness. Tracer techniques with radioactive isotopes have been used in laboratory studies to evaluate the impregnation of pulping chemicals during - chemical pulping [ 3 5 ] and chern imechanica L pulp ing [6 ]. In addition x - ray fluorescence has . - B. Figure 1. >A. Position of samples for impregna tion in transverse projection of birch log . B. Dimensions of sample for impreg nation studies. 57 * Excess solution was drained and free solution on the outside of the sample was re moved by wiping , Thermal post treatments were out by on some samples by heating the . ture - - carried impregnated 80°C or in saturated steam in an autoclave at 120°C for 25 minutes. The radial and tangential sides of the wood at samples block were cut with a Reichert "Om E" sledge microtome to give a sample from the centre of the impregnated block with dimensions of 30 x 2.5 x 2.5 mm in the axial, radial and tangential directions respectively , as shown in Figure 2. Thus, the effects of diffusion of sodium sul phite from the tangential and radial directions were excluded and the transport of sodium sul - windows corresponding to sodium and sulphur were divided by x ray counts arising from background radiation in the window corresponding to chromium. In this manner , a sodium and sulphur content of the wood independent of the surface roughness and microsope magnification was - obtained. 1 500 c 3 O o - phite into the wood primarily through the cavi ties in the wood structure in the longitudinal direction was observed. Immediately after cut ting , the samples were frozen in liquid nitrogen to avoid further changes in chemical distribu - The samples were then freeze dried , tion. mounted on carbon stubs and coated with carbon for examination by scanning electron microscopy and energy dispersive x ray analysis of sulphur and sodium. - Energy (Kev) Figure 3. EDXA spectra of birch wood impreg nated with sodium sulphite. - The distribution of sulphur and sodium as a function of sample penetration was determined by collecting x ray counts for 100 seconds every 5 - - mm along the sample using a microscope magnifi A magnification of about cation of 40 times. 230 times was used to determine the degree of impregnation in different types of cells using a " selected area system" in the equipment that made it possible to choose fully opened cells with clean surfaces. The readings from differ ent morphological parts are mean values of read - ings of several cells of the same type at the As same distance from the end of the sample , seen in Figures 4 and 5, all measurements of 2.5 mm 2.5 mm Fig ire 2. The centre of the sample examined by SEM EDXA. - Sulphur and sodium distributions were determined with a Princeton Gamma Tech. System III x ray analyzer together with an Akashi DS 1 30 scanning electron microscope , When the sample was bombarded with electrons in ‘.he sample chamber of the microscope, x rays at energies characteristic of sulphur and sodium e emitted collected and displayed as an • •:» ergy o.cpersive x ray spectrum as shown in Figure 3. The x ray counts in the spectral - - # . - F? - Three dimensional sample . view of birch spectroscopy . Figures 7 and 8 show that there is excellent correlation between values obtained different cells were made from the radial side of the sample to expose all different cell types in one plane. - - by SEM EDXA and those from ion chromatography and atomic absorption spectroscopy. < if ) if ) x c O if ) zh < 2.0 if ) < < o o - » o . 468 X Figure 5. O 1.5 1.3 o 20 KU 1.2 0.8 E CL a 0.4 ra Z Fi 'are 7. 50 U 4098 1.6 ro • - z 3 t/> OEDXA AAS ANALYSIS > < 2.0 in Radial side of birch sample showing vessel , ray and libnform cells in one plane 0 10 20 30 DISTANCE ALONG WOOD SAMPLE ( mm. ) - The distribution of sodium deter mined by SEM EDXA is the same as that determined by atomic absorption spectroscopy. - . RESULTS AND DISCUSSION As seen in Figure 6, sodium sulphite is distributed throughout the length of the sample. A fairly even distribution of both sulphur and sodium is seen; the amount of sulphur in the middle of the sample being about 80 per cent of that found at the ends. •• if ) if ) < 1.0 *t5 > 0.9 CL 3 < X c 0.8 2.0 o - 1.9 if ) O if ) h Z 3 o 1.8 Z 1.7 if ) - z 3 O - o h z if ) if ) X Z if ) if ) GC 0.5 O 6.0 O - h 3 o 5.0 o o ' 0 10 20 30 DISTANCE ALONG WOOD SAMPLE ( mm. ) S 6.0 if ) if ) Figure 8. - Z 3 O o _ o 1.5 o 5.0 10 20 30 DISTANCE ALONG WOOD SAMPLE ( mm.) Figure 6. - Relative sulphur distribution deter mined by SEM EDXA is the same as that determined by combustion followed by ion chromatography. - h 1.6 7.0 O 3 O h 7.0 o UJ 3 2 0.6 o • x £i o o - • z < OEDXA ION CHROMATOGRAPHY ANALYSIS The content of sulphur and sodium in - birch impregnated with sodium sul phite decreases toward the middle of the sample. Sulphur and sodium distribution in wood oamples previously analyzed by SEM EDXA were determined by ion chromatography and atomic absorption spectroscopy respectively. The sample was divided into 5 pieces for analysis of sulphur by ion chromatography and into 9 pieces for analysis of sodium by atomic absorption - - In order to determine whether the mechani cal action of the microtome knife changed the distribution of chemicals in the sample, a wood block twice as long as normal (60 mm ) was impregnated and then divided into two 30 mm samples each with one end from the middle of the original sample. These samples were cut with a microtome each in different directions ; one from the middle to the end and the other from the end to the middle of the original 60 im\ sample. Figure 9 shows that sectioning impregnated wood samples with a microtome does not significantly change the distribution of sodium sulphite. 59 Decreasing the moisture content froc 38 to 12 per cent increases the amount of sodium sulphite 8 transported into the chips from 0.70 to 0.92 L/od kg of wood and also increases the uniformi o 'I 7 - ty of chemical distribution in the wood , Steam ing time appears to have a greater affect on the degree of uniformity of impregnation of wood / 6O 5 \ \ \ \ \ \ O ' 0 ' 4 - V b 3 10 20 30 10 KNIFE DIRECTION CUT FROM ORIGINAL MIDDLE 20 30 KNIFE DIRECTION CUT FROM ORIGINAL END DISTANCE ALONG WOOD SAMPLE (mm. ) Figure 9. Microtome knife direction has no effect on the distribution of sodium sulphite. - Energy dispersive x ray analysis was used to study the effect of moisture content of wood , time, pH of sodium sulphite solution and thermal treatment of impregnated samples on the distribution of chemical in the wood samples. The initial moisture content and steaming time determine both the extent of mpregnation and the distribution of sodium sulphite in the wood , as seen in Figure 10.. steaming INITIAL MOISTURE CONTENT ( % ) 12 38 38 J 0 T D 3 j o o 7 with sodium sulphite solution , Decreasing the steaming time from 15 to 10 minutes decreases the amount of sodium sulphite solution trans ported into the wood from 0.70 to 0.45 L/od kg This decrease is accompanied by a of wood. large decrease in sodium sulphite in the centre of the sample. Heating impregnated wood above water at STEAMING TIME ( min. ) 15 15 10 - LIQUOR UPTAKE ( l / kg ) 0.92 0.70 0.45 Cf 80*C for 25 minutes has only a small effect on the distribution of sodium sulphite, as seen in Figure 11. When the thermal treatment of impregnated wood was carried out at 120 *C, the distribution of sulphite, as shown in Figure 12 was the same throughout the length of the sample. Therefore, the uneven distribution of sodium sulphite can be equalized after impregna tion by steaming at 120 *C. - l UPTAKE •NO THERMAL POSTTREATMENT LIQUOR O LIQUOR UPTAKE 0.52 l / kg, THERMAL POSTTREATMENT 25 m i n. 80 *C o 6 U) O O / 4 CO CO 3 O 2. O i 0 10 20 30 DISTANCE ALONG WOOD SAMPLE ( mm. ) 4 . 3 Figure 11. 5 D Z> 2 0 30 20 10 DISTANCE ALONG WOOD SAMPLE ( mm. ) pigure 10. \ 5 6 5 0.60 / kg, Decreasing the moisture content of wood and increasing the time of steaming from 10 to 15 minutes increases the amount of chemica 1 penetration into the wood. Heating to 80*C after impregnation has little effect on the sulphite distribution in birch. As seen in Figure 13, changing the pH of the sodium sulphite solution in the range 4 to 12 has no significant effect on the distribution of sulphur in the longitudinal direction of wood . • LIQUOR P LIQUOR UPTAKE 0.85 l / kg , NO THERMAL sampLes indicates a uniform distribution of sodium s.: . pnite in the ray and libriform cells and a slightly higher sodium sulphite content ir. the vessels at a constant distance from the end POSTTREATMENT O LIQUOR UPTAKE 0.80 , / kg THERMAL POSTTREATMENT 2 5 m i n 1 2 0 *C 7 O cn H Z " D O O of the sample. It should be noted that small differences in the sulphur content may be masked by limita tions in the resolution of this technique. Although one cell type was exposed to the electron beam on the sample surface, electrons For scatter as they penetrate the sample , example, under the experimental conditions used , x rays are likely to be generated from regions more than 30 urn from the surface being examined . 6 5 a) 4 (/) H 3 o 2 z G - Since the average diameter of birch fibres is about 18 [ini, the sulphur content determine* for one morphological region will .nclude a contri bution from an adjacent morphological region. & 30 20 0 DISTANCE ALONG WOOD SAMPLE ( mm. ) 10 •O VESSELS *• Figure 12 Heating birch impregnated with sodium sulphite to 120 *C increases the sulphite content in the centre of the wood sample to the same level as the ends. CHEMICALS O Na2S03 NaOH Na2S03 < NaHS03 * Na0H A Mg ( HS 03) 2 pH 8 o o o - 6 i O 5 if ) 4 > z - 3 o 7 O 6 2 0 5 Figure 14. 4 z O o 3 2 10 30 DISTANCE ALONG WOOD SAMPLE ( mm. ) to (/) A LIBRIFORM CELLS h O O RAY CELLS O cn (/ to Z 7 O 12.0 • > - f 0 10 20 . The pH of the sodium sulphite solu tion has no significant sulphite distribution. - effect on Stone and Green [13] have shown that the penetration of chemical solutions into hardwood via the vessels. They have postulated that transport of chemical from the vessels into the surrounding libriform ceils occurs by diffusion. As shown in Figure 14, analysis of EDXA at high magnification , of the different types of ceils in the impregnated samples occurs For a given set of impregnation conditions the relative distribution of sulphite ion as a function of distance from the sample end is about the same for ray and libriform cells. The sulphite content of the vessel cells is slightly higher than those of the ray and libriform cells. 30 DISTANCE ALONG WOOD SAMPLE ( mm.) Figure 13 20 There are extensive pit regions in the vessel ray cell contact areas shown in Figure 15 and a considerable number of pits connecting the ray cells to each other as seen in Figure 16 [9]. Figure 17 shows that although the libri form cells have less pits , - most of them are concentrated in the tapered ends of the cells that are adjacent to the ray cells , Therefore , - it is likely that much of the initial impregna tion of birch wood occurs via liquid flow of sulphite solution from the vessels through the ray cells into the libriform cells by means of the pits. 61 chemicals move towards the centre of the sample. , ‘ he When a bisulphite solution at pH 4 is used ratio of sulphur to cation remains the same as the solution penetrates the wood block , as seen No ion exchange between the in Figure 18. cation and the acidic constituents of wood occurs due to the low basicity of the bisulphite A constant S/Mg ratio does not mean that anion. diffusion is not operative at pH 4. Figure 15. The pit region necting to ray cells. birch libriform to the connecting pits with cells ray cells. pH LIQUOR UPTAKE C N »>SO) N«OH 12.0 05 0.71 0.80 t NaHS03 • N«0H 8.3 4.0 0.7Q 0 65 * 6 C7> 5 or if ) O . £ Mg(HS03); 5 cn n »- z s* 8 sc 4 V e I | g n I f I c a t I o n s a n d P r o c e d u r e s f o r O r g a n o s o l v , I 1qnI ns Analyses and Calculations for Orqanosclv Lignin Condltlons of de 1 IgnIfIcatI on for Run 29 chosen similar to those used In batch xper imentat Ion conducted by S . TIrtow Idjojo molecular weights (M ' ,M ' ) and r e l a t e d parameters w n ^ . . Sarkanen and were a s f o l l o w s: s o l v e n t m e t h a n o l / w a t e r ( 7 0 / 3 0 . v / v ); c a t a l y s t - 0 0 1 M 1 * 2 S04 * f l o w r a t e , r 1 7 m L m i r - a n d t e m p e r l u r e 2 5 2° C . The d e I I g n I f I c a t I o n was c a r r i e d o u t Hth K V * ubstantlally ns previously OnscrI bed for the IIkaiine reaction except that here the resloual tissue was washed exhaustively on \ f i l t e r the methanol -water so I i t I on ( free of a t a l y s t ), t h e n w i t h a c e t o n e a n d f i n a l l y w i t h •. Estimation of weight and number average were conducted by low angle laser light scat - t e r l n g (LALLS ) and vapor pressure osmometry ( VPO) as p r e v i o u s l y descr 1 bed . 7 / ® and r e s u l t s are presented graphically C a r b o n, h y d r In Figure 2. gen and methoxyl analyses were c a r r i e d o u t (G a l b r a i t h L a b o r a t o r 1 e s , KnoxvI I 1 e, TN. ) on three organosolv l i g n i n f r a c t i o n s and the mean molecular weight f o r a C6- C 3 s t r u c t u r a l u n i t was found to be M 20 7 . o RESULTS AND DISCUSSION For each alkali lignin fraction, the n u m b e r THOUSANOS BO a n d w e i g h t a v e r a g e molecular w e i g h t s, M * , a n d n, I Mw’, , a n d the p o 1 y d I s p e r s i t y Index , 70 , 80 _ 50 H I r termined by previously = M w* , I / Mln,' I were d e2, 3 d e s c r i b e d procedures. (Table 1 ana F i g u r e 1) . As d e 1 ignIflcat I o n p r o c e e d e d , M * Inc r e a sed, n, I a n d M V. Increased m a r k e d l y so p oly that the , I d l s p e r s i t y rose from a b o u t 1.8 t o n e a r l y 10. T h e second virI a coefficient A , fluctuated a r o u n d a s l i g t l y p o s i t i v e value and t h e n d e c l i n e d s 1 gn i ficant 1 y during t h e latter s t a g e s of t h e d e 1 I g n I f I c a t i o n. The a n i s o t r o p y p a r a m e t e r , 6, declined m o n o t o n Ica 11 y from 0.16 t o 0 . 0 1 over the course o f t h e deI IgnIfIcatI o n r e a c t i o n , while the refractive Index r e m a i n e d n e a r l y constant a t a b o u t 0.16. These t r e n d s a r e in general a g r e e m e n t w i t h those w h i c h w e observed w i t h FTR d e 1 IgnIfI c a t i o n of W e s t e r n Hemlock u s i n g a n a q u e o u s 1.0 N NaOH s o l u t i o n s , 8 For t h e o r g a n o s o l v f r a c t i o n s, similar results w e r e obtained as shown In F i g u r e 2. v . - - ^ ECD i cc 40 f 3 o * 30 _ £ 20 . 10 . - D O - V 9 0 i 0 0 1 0. 3 0 2 0 4 0 5 . 0 7 0 6 0 9 0 B 1 S Figure 2. Weight and number average molecular weights of individual ( 0 ') and cumulative * - A HW \ ( ^- Hn •) fractions of organosolv Mr lignin, versus weight fraction of lignin in the solution. 7 THOUSANOS = - 80 l i g n i n found In t h e sol p h a s e , s 1 g', a t several Intervals as t h e alkali d e 1 ignIfIcatI o n p r o c e e d e d are s h o w n In Table 3. U s i n g these molecular w e i g h t a n d sol p h a s e d a t a , several p a r a m e t e r s a s s o c i a t e d w i t h the model w h i c h w e a r e s t u d y i n g for the sol p h a s e so H 40 . ' 53 30 _ l i g n i n fractions were calculated b y u s e of p r e v i o u s l y described d e f i n i t i o n s a n d p r o D O c e d u r e s. 20 . I io . o o 0 1 0 2 . 0 3 0 4 0 5 0 8 . 0 7 0 8 0 9 1 figure 1. Weight and number average molecular weights of individual ( 0 Mw'• O ') and cumulative A - V •WnM fractions of alkali lignin, versus weight fraction of lignin in the solution. From the M nt I a n d M » , w, I results obtained for ach * fraction, t h e c u m u l a t i v e m e a n values o f each molecular w e i g h t t y p e , M * and M ' , were h, , Culated for the alkali l i g n i n and alsoJ t h e Pa I fr actlons a n d results are shown In F i g u r e s 1 ^^ p r o c e e d s. As t h e sol p h a s e p r o p o r t i o n Increases, the e x t e n t of reaction o f p r i m a r y c h a i n s, p * , (F i g u r e 3) the w e i g h t average d e g r e e of p o l y - m e r i z a t i o n of t h e p r i m a r y c h a i n s, y'(F i g u r e 4) W a n d the c r o s s l i n k i n g d e n s i t y , r * , (F i g u r e 5) also a r e found t o g r o w s t e a d i l y larger. From the now e s t i m a t e d values o f p' a n d o for each sol a l k a l i l i g n i n p h a s e fraction (Table 3), the c h a i n b r a n c h i n g p r o b a b i l i t i e s, - described relationships Shown In Table 2 are a n a l y t i c a l results Wh c h Indicate that the mean molecular w e i g h t o f a structural unit In alkali 1 IgnI n w a s M 204. , Slm| | ar a n a l y s e s showed M o n . a , have been calculated b y u s e of p r e v i o u s l y and 2 sol v P r e p a r a l I o n , ^ Results for the alkali l i g n i n are shown In Table 3 from w h i c h It m a y be s e e n that the c u m u l a t i v e w e i g h t and n u m b e r a v e r a g e d e g r e e o f p o l y m e r i z a t i o n, x ' and x ' , the p o 1 y d I s p e r s 1 t y w n I ndIcIes, r x / x , a n d the w e i g h t a v e r a g e d e g r e e of p o l y m e r !zatIon o f t h e p r i m a r y c h a i n s y ', all Increase s t e a d i l y as del IgnIfIcatI on s ( - 201 for t h e organo The p r o p o r t i o n of t h e total - £ a n d results a r e s h o w n In FIgure 6. A c c o r d i n g t o Flory 11 , t i c a l value, a a c , a t t h e gel C - - (f i) 1 , where f a ^ reaches a c r i where point - functIona 1 It y 67 0 9 . 08 » .07 . . . 0. 94 0 93 . jr *T f 0 8 0 9 08 0. 9 .05 . 0 88 4 O r’ 0. 8 4 0 83 4 4 COTTON9000 0 COTTON9000 f 4L H£ UL OCX D 0. 8 7 -- . 04 . 03 H 03 . A O * * 0. 86 P* ' f -- ORGANOSOLV COTTON9000 NoOH COTTON9000 No OH 9CSTERN HCULOCK - OR CANOSOL V No OH No OH 0 78 01 . 0. 7 6 0 74 0 0 1 0.3 0.3 0.4 I 0.5 T T 0.6 0 7 0 T 0.8 0.9 T 0. 1 0 1 0. 3 T T T T 0. 3 0 4 0.5 0 6 s figure 4. . 0 7 . S Weight average degree of polymerization of primary chains as a function of s, (Symbols as in Figure 3.). Figure 5. Crosslinking density as a function of sr (Symbols as in Figure 3.) . 0 3 30 0. 3 38 N 0. 38 0. 2 34 fc 00 . 23 33 302 30 o CC ° \ A N A * Yw• 1 8 4 16 0 0. 1 CL f 4 °w - o°1 COT TON9000 ORGANOSOL V No OH COTTON9000 9t STERN HEULOCK No OH - - 14 A * 0 1 ? X . a O o. 1 0 13 CD 0 a .0 10 .0 e . T T 0 3 0 3 . 0 1 0 4 0 5 . 0 8 T 0 7 S Figure 3. o o 6 0 f 0. • 0 9 1 0 . T T T T 03 04 06 08 0 1 0. 1 3 0 xw i/ Fxtent of reaction of primary chains as a function of weight fraction of lignin in solution. •: A organosolv lignin from Black Cottonwood r . alkali lignin from Black Cottonwood. V alkali lignin from Western Hemlock. --- c T * Figure 6. Branching probability as a function of a. A alkali lignin from Western Hemlock. 7 alkali lignin from Black Cottonwood. organosolv lignin from Black Cottonwood. ^ --A ^\ T h u s t h e g e l p o i n t a n d a a r e a p p r o a c h e d a s x' c w a p p r o a c h e s i n f i n i t y, o r e l s e a s 1 / approaches z e r o. s y s t e m, a n d In F i g u r e 6, t h e v a l u e s now found f o r a are plotted against l/ \ x A l t h o u g h t h e c u r v e Is n o t l i n e a r , It has b e e n e x t r a p o l a t e d t o l /x i 0 b y use o f a f i t t e d p o l y n o m i a l . T h e w l i m i t i n g v a l u e found Is 0 . 3 3 w h i c h Is In a g r e e m e n t w i t h t h e t h e o r e t i c a l v a l u e o f 0.33 e x p e c t e d for a tetrafunctIona 1 b r a n c h p o i n t S l m i l a r calculations have been made for the o r g a n o s o l v Cottonwood l i g n i n f r a c t i o n s. T h e s e r e s u l t s, a l o n g w i t h t h o s e p r e v i o u s l y r e p o r t e d f o r a n a l k a l i H e m l o c k l i g n i n a r e s h o w n In F i g u r e s 3 t h r o u g h 6. xJ ^ 68 ^ is substantially distant from the v a l u e o f 0.50 w h i c h should b e a s s o c i a t e d w i t h a trIfunctIonal b r a n c h p o i n t a s s e m b l y . For Black cottonwood the results d e r i v e d from the n o w r e p o r t e d d e 1 Ign 1 fIcatI o n e x p e r i m e n t s, conducted w i t h both a n alkaline a q u e o u s s o l u t i o n a n d an a c i d i c o r g a n o s o l v s o l u t i o n, - - a l o n g w i t h those p r e v i o u s l y o b t a i n e d w i t h W e s t e r n Hemlock w o o d lignin, s e e m t o confIrm a t least t h e p e r m i s s i b i l i t y of a p p l i c a t i o n or the d e g e l a t l o n model t o l i g n i n s from both a g y m n o - Isolated under b o t h acidic a n d a l k a l i n e c o n d i t i o n s. Also It a p p e a r s that the l i g n i n s In a t least one gymnosperm (W e s t e r n Hemlock) a n d o n e a n g l o s p e r m (Black Cottonwood) are c o m p r i z e d of cross linked p o l y m e r c h a i n s w h i c h manifest tetra f u n c t i o n a 1 L . Yan. J.F., Mac r o m p 1 ecu 1 e s, 14, 1438 (198 1) 5 Yan, J.F., a n d J o h n s o i, D.C., J . A p p l i e d . P o l y m. Sc I , 26 , 1623 (1 98 1) . 6 Yan, J. F., Pla, F • / Kondo, R., Dolk , M. a r d M c C a r t h y J o s e p h L., Mac r o m p 1 ecu Ies, 1 7 , 2137 (1984). 7 - - International S y m p o s i u m on W o o d a n d P u l p i n g Chem 1 s t r y t Tsukuba S c i e n c e C i t y , J a p a n (1983) . 8 Dolk, M ., Pla, F ., Yan , J .F., a n d M c C a r t h y J o s e p h L., Mac r o m p 1 e c u 1 e s, s u b m i t t e d for p u b l i c a t i o n,(1985) . 9 TIrtowidjojo, S., M . S. T h e s i s, U n i v e r s i t y o f W a s h i n g t o n (1983) . branch p o i n t s. A s u b s t a n t i a l l y lower c r o s s l i n k i n g d e n s i t y a p p e a r s t o exist In Cottonwood lignin a s com - Hemlock l i g n i n, a n d p e r h a p s this difference Is characteristIc of all a n g l o s p e r m versus gymnosperm lignins. I n v e s t i g a t i o n s In p a r e d w i t h the D o l k, M., Kondo, R • / W o e rne r , D ., Lai , D. a n d M c C a r t h y , J .L., P r o c e e d i n g s o f t h e s p e r m a n d a n anglosperm t h i s field a r e c o n t i n u i n g. ACKNOWLEDGMENTS T h e a u t h o r s are grateful for the s u p p o r t Science Foundation In Grant N u m b e r s CPE 8121442, a n d for the p e r s o n n e l a s s i s t a n c e a n d use of facilities of the W e y e r h a e u s e r C o m p a n y of Tacoma , W a s h i n g t o n a n d also the Ecole Francalse d e P a p e t e r l e o f t h e National Po 1 y t e c h n I q u e Institute, U n i v e r s i t y o f Grenoble, France. T h e h e l p f u l discussions a n d c o m m e n t s o f our c o l l e a g u e Professor K.V. Sarkanen are a l s o much a p p r e c i a t e d. p r o v i d e d b y the National REFERENCES AND NOTES 1a An NSF I n d u s t r y / Un 1 versIty C o o p e r a t i v e Research A c t i v i t y (W e y e r h a e u s e r Company a n d U n i v e r s i t y of W a s h i n g t o n : Grant No. CPE 8121442) . - lb - NSF Post doctoral Research Scientist 1983. Permanent address : Laboratoire d e Chlmie Papetlere Ecole Francalse d e P a p e t e r l e, DomaIne UnIversIta Ire B.P , 65, 38402. Saint - Martin d H e r e s, France. lc Present a d d r e s s: Yan Research, 3801 SW 326 th Street , Federal W a y , Wa . 98023. Id Co PrInIcI p a I I nvestIgators for NSF Grant No. CPE 8121442. 2 - - Pla , F • / Doctorate Thesis, Etude d e 1 a Structure Mac r o m p 1 ecu 1 a 1 re d e s L i g n i n s U n i v e r s i t y of Grenoble, France (1980) . . 3 Pla , F., and Robert , A., Ho 1 z for s c h u n q , 38 , 4, 213 (1984) . 69 - Table 1 Some C h a r a c t e r I s t I c s o f R 1 5 L i g n i n F r a c t i o n s: P u r i f i c a t i o n M e t h o d Two ( a) F ( ) a F l F 2 F 3 F 4 F- 5 ° . , . A xlO 2 w i 0.107 0.235 0.324 0.274 0.301 0.195 0.275 0.363 2250 3375 3280 3170 4725 7760 10280 11430 -1 . 2 -2 . 1 0.394 0.329 0.234 0.479 0.405 0 . 1.3 0.478 0.574 0.642 0.782 0.901 0.963 3715 3540 5010 4770 5900 6450 1 7575 24200 24050 36200 4 3600 54900 95 135 240 U) ( m oil e c m 3 6 ,) dn/dc 4 3 "2 2.5 7.7 40 . - M ( g) 52 70 - M n ,i (m i n ) 13 21 30 F- 6 F 7 F 8 F 9 F 10 g (cm g M ) .- 0 0 - 0.14 0.12 0.187 0.192 0.184 0.188 1.4 0.09 1.3 0.6 0.9 1.7 1.1 0 10 . 0.195 0. 1 9 1 0.189 0. 1 9 3 0. 1 0 0.11 0.190 . 0 192 0.11 0.06 0.04 0.01 . * Table 2 C h a r a c t e r i s t 1c s o f C e r t a i n L i g n i n F r a c t i o n sCa) Analytical C H 0 -O C H 3 Unit ( Z) ( Z) (Z) ( Z) Weight Fraction Calculated C 6 - C 3 U n i t ( b) F l - 56.79 6.02 37.19 13.91 210.1 - C H 9 59.44 6.22 34.34 15.43 202.1 C.H 0 ( O C H.) F- 1 0 58.85 6.17 34.98 13.14 200.8 C „H 0 (O C H J F 5 — F r a c t i o n s f r o m R 1 5 u s i n g p u r i f i c a t i o n M e t h o d T w o; of C -C 3 s t r u c t u r a l u n i t 6 - M o 204.5 9.8203. 9 4 ( 0C H 3^ > 0 . 9 4 9 9.55 3.33 9 9.84 3.54 3 1.01 3 0.85 Mean molecular weight . *1 Table 3 Properties of Fraction ( ) Llqnin Fractions a F l* - F 2 - F 3 - F 4 - F 5 - F 6 - F 7 - F- 8 F- 9 F 10 0 . ^ 00 0.195 0.275 0.363 0.478 0.574 0.642 0.782 0.901 0.963 4 725 6200 7390 8370 10580 12860 14050 18020 21380 23540 2250 2685 2835 2910 3070 3140 3270 3465 3665 3770 M w ; / n* j 2.1 2.3 2.6 2.9 3.5 4.1 4.3 5.2 5.8 6.2 » X 23.1 30.3 36.1 40.9 51.7 62.9 68 7 . 88.1 105 115 1/5 * 0.0433 0.0330 0.0277 0.0244 0.0193 0.0158 0.0146 0.0114 0.0095 0.0087 n * 11.0 13.1 13.9 14.2 15.0 15.4 16.0 16.9 17.9 18.4 P' 0 . 9 0b 0.919 0.921 0.920 0.921 0.922 0.925 0.927 0.931 0.933 P* 0.006 0.008 0.014 0.018 0.024 0.026 0.025 0.027 0.025 0.026 Qf 0.055 u 085 . 0.137 0 1 74 . 0.220 0.233 0.237 0.255 0.257 0.265 y7 ' 20.3 23.7 24.3 24.0 24.3 24.6 25.7 26.4 28.0 28.8 - -. Parameter 8 M' M* n .J M' . . w w X w (a) — . ( b) F- l * Fractions from R 15 . v i 0.031 0 . 100 D e t e r m i n a t i o n s w e r e m a d e f o r t h e m i x t u r e s o f F- 0 p l u s F- l w h i c h i s i d e n t i f i e d a s F-l* i n T a b l e 3 ( a) l* s Time Fraction F 0 plus F l - 2.1 2.3 3.1 3.6 4.7 6.8 4.8 7.6 7.4 8.5 .1 WHY DOES CHLORI NATION AND E/ FRACTION FAIL TO PELIGN IFY UNBLEAC HED KRAFT PULP COMPLETELY ? R.M. Berry and B.I. Fleming pulp reaches the chlorin ation tower . It is also known that more retent ion time, often 45 min - pulp and Paper Researc h Institu te of Canat.a 570 St. John ' s Bouleva rd pointe Claire, P.Q • » Canada H 9 R 3J9 utes, is necessa ry in the tower to complet e the chlorin ation, during which time pulp viscosi ty ABSTRA CT hypoth esis has been develop ed to explain the qualit ative feature s of the kineti cs of chlorin ation. It is postula ted that alkali labile 'blockin g groups ' are formed during chlori nation and that these allow residua l lignins to react only very slowly with chlori ne. Hither to , the failur e of chlorin ation and extract ion to remove all the lignin has been ascrib ed to incompl ete reactio n caused by the failure of chlorin e to diffus e to all parts of the fibre wall. Evidenc e is given to show that the present diffus ion theorie s are inadequ ate, and that the new hypothe sis, invoki ng chemica l rather than physic al restra ints, is more suit A new . able KEYWORD S: deligni ficatio n and second , a limiti ng CE Kappa number. The literat ure contai ns many referen ces to the fact that chlorin ation is 60-80 % complet e in 2 minutes or less [3 - 7] and that many of the chlori nation reactio ns take place before the can be lost [8]. The literat ure also describ es the concept of a limiti ng CE Kappa number [ 2 , 3, 6, 9] There have been fewer attempt s , however , . to explain why it takes 40 minutes ( at tempera tures below 35 C ) to get rid of only 0.5 wt % of - - lignin and why some lignin always remains. 30 r 25 4) n E u RAPID PHASE 20 / c 5 We first questioned the diffusion theories 4stn - when we studied a sequence cor. isting of repeat ed rapid chlorination (CR ) and extraction We observed that if chlorination is stages. terminated after the initial rapid phase, and the pulp is extracted with alkali , the residual lignin appears to be reactivated to chlorine (Figure 2). Treating CRE pulp with chlorine produces delignification at the original fast rate, as would be expected from the diffusion theories. However , prolonging the second chlorination beyond 2 minutes leads, once again, to slow lignin removal , Again an alkali treat ment restores the rapid rate. It is significant that each chlorination stage is capable of fast reaction with only a portion of the remaining lignin and after that the slow phase sets in. The diffusion theories cannot effectively - for this observation ; complete removal of lignin would be expected after the second extraction stage. . * We were able to think of only one explana tion for the observations illustrated in Figure 2 that a chemical rather than a physical mech anism is operating. However , before abandoning the diffusion theories, we decided to carry out several experiments designed to reveal a diffusion controlled mechanism for chlorination , 11 should it exist. If Karter and Bobalek are correct and chlorolignin in the fibre wall presents a barrier to further chlorination, then the lignin which is behind the barrier (i.e • » what remains . - 4:? f» . . r > it .i jcount - — - - t » > / 0 0 — . 1» **r ; •V , 2 Unbleached Pulpi C stage t E stage: -- 2 25 70 70 70 70 50 * *A * - *i I .* - . & ..1 i * after the barrier is removed ) must not have been v * chlorinated. To test this idea we measured the Kappa numbers and chlorine contents of pulps \ As which had been chlorinated and extracted. , the CE pulp contained a « shown in Table I t ^ • - significant amount of chlorine, which is presura ably bound to the residual lignin , The conclu sion is that chlorine has managed to penetrate - throughout the lignin matrix. Kuang's results [12] are also pertinent. He found that when kraft pulp was chlorinated , chlorine penetrated to all morphological regior . and "the topochemical distribution of the chlorine , in chlorinated kraft pulp is similar to that of the lignin." Moreover the photomicrographs of the CE pulp [12] did not show a band ofv unreacted lignin in the middle off the fibre wall , as one might expect from the. • theory of Karter and Bobalek ; the re idual lignin was evenly dispersed throughout the fibre wall. .> i .r r the - » » - .tu . "!i 1 \ * . Changes in Chlorine Content of CE Pulp with Time of Alkaline Extraction 15 30 45 60 A 40 same sharp transition from 4 4 rapid to a slow phase of delignifica t tion is found when the chlorination ' is repeated after extraction , When » multiple chlorinations were used ( *• rt the initial chlorinations were v b ) done for 2 minutes only , Bleaching •* conditions were the same as for * Figure 1 U vt The Table I Extraction Stage Time, min. Temp., *C 3K A 30 20 Time ( t ), min Ml S v• — uA 10 Figure 2. % O CE Kappa No., Organic Chlorine, % on o.d. pulp Calculated Cl atoms/C9 6.4 0.33 0.31 0.24 0 . 21 0.24 1.9 5.4 5.4 4.9 4.8 . 2 1 1.6 1.6 1.8 . black spruce kraft pulp; Kappa No• 30.8 on o.d . pulp; 45 min at 25 C ; 3.5% consistency , 6.2 « 3.4? Naf)H on o.d. pulp ? 10% consistency. # # . The observation was explained by postulat- > - 30 ( ing ing that bleaching is controlled by diffusion of oxidant through a thick "water layer surrounding The hypothesis can be used to each fibre". explain rate changes particularly in the rapid It does not phase of a bleaching reaction, however, explain either a limiting CE Kappa number , or the transition from a rapid to a slow phase of chlorination. . I o «* •* 25 * - * o JO E '- i 20 3 c (Q CL O CE C* ECE A C*EC*ECE 15 Q. 5 O O We first questioned the diffusion theories > - when we studied a sequence cor isting of repeat ed rapid chlorination ( CK ) and extraction We observed that if chlorination is stages terminated after the initial rapid phase , and " — 0 10 0 20 lignin appears to be reactivated to chlorine (Figure 2). Treating CRE pulp with chlorine produces delignification at the original fa6t rate, as would be expected from the diffusion theories. However , prolonging the second chlorination beyond 2 minutes leads, once again, to 6low lignin removal , Again an alkali treat ment restores the rapid rate. It is significant that each chlorination stage is capable of fast reaction with only a portion of the remaining lignin and after that the slow phase sets in. The diffusion theories cannot effectively count for this observation ; complete removal of lignin would be expected after the second extraction stage. We were able to think of only one explana tion for the observations illustrated in Figure 2 that a chemical rather than a physical mech anism is operating. However , before abandoning the diffusion theories, we decided to carry out several experiments designed to reveal a diffusion controlled mechanism for chlorination, 1i should it exist. If Karter and Bobalek are correct and chlorolignin in ' the fibre wall presents a barrier' to further chlorination, then the lignin which is behind the barrier (i.e• i what remains - t i - - — > - > l4 lf « J ,r < •• • I it * . Figure 2. •• . Table I. 2 IS 30 45 60 Unbleached Pulp * C stagei E stage s -- 25 70 70 70 70 . As which had been chlorinated and extracted. shown in Table I, the CE pulp contained a - significant amount of chlorine, which is presum ably bound to the residual lignin. The conclu sion is that chlorine has managed to penetrate throughout the lignin matrix. Kuang's results [12] are also pertinent. He found that when kraft pulp was chlorinated , the chlorine penetrated to all morphological regior i and "the topochemical distribution of the chlorine in chlorinated kraft pulp is similar to that of the lignin." Moreover the. photomicrographs of the CE pulp [12] did not show a band of unreacted lignin in the middle off the fibre wall, as one might expect from the theory of Karter and Bobalek ; the re idual lignin wa6 evenly dispersed throughout the fibre wall r . - I * / CE Kappa No * Organic Chlorine, % on o.d. pulp Caleulated Cl atoms/Cq 6.4 0.33 0.31 0.24 0. 21 0.24 1.9 2, l I .6 1.6 1.0 5.4 5.4 4.9 4.8 black sprure kraft pulp; Kappa No i 30.8. . 21 Cl .. on o.d. pulp ? 45 min at 25 *0; 3.5% consistency , 3.41 ria6n on O d pulp; 101 consistency 6 .. 1 n - Changes in Chlorine Content of CE Pulp with Time of Alkaline Extraction . 0 The same sharp transition from a rapid to a slow phase of delignifica tion is found when the chlorination is repeated after extraction, When multiple chlorinations were used ( ** A ) the initial chlorinations were done for 2 minutes only , Bleaching conditions were the same as for Figure 1 U i Extraction Stage Time, min Temp., *C v 50 after the barrier is removed ) must not have beea' chlorinated. To test this idea we measured the Kappa numbers and chlorine contents of pulps • fl \ 40 .3 to tv 30 Time ( t ), min . the pulp i6 extracted with alkali , the residual ‘J r L1 A . In a second experiment, we exposed pulp to excess chlorine. If the reaction is diffusion controlled , the CE Kappa number should eventual ly reach zero , However , even after 7 days with a 11.5 % charge of chlorine, the Kappa number of a bleachable grade pulp (starting Kappa number ~ 30) had not reached zero (Table II ). As stated long ago by Giertz [10] "it is impossible to delignify pulp quantitatively in a single chlorination." in a CE sequence , The Kappa numbers of the extracted pulps were identical (Table IV ). - Table II. Limiting CE Kappa Number after Extended Chlorination Table III. Comparison of the Bleaching cl Kraft Pulp from Douglas Fir and Balsam Fir Pulp Type Sequence Balsam Fir Douglas Fir CE CE 29.7 29.1 Balsam Fir Douglas Fir DE DE 30.5 31.5 Kappa Number Initial Final * 4.9 5.1 •r* 6.8 6.9 The Chlorination Time, Cl2 Charge, % on o.d. pulp CE Kappa 5.7 4.5 Number * Each number represents the average of the results from three bleaching runs. 0.2 x initial Kappa No. (% Cl on o.d. pulp); 45 min at 25 C; 23.5 % consistency. D-stage: 0.076 x initial Kappa No. (% CIO on 2 o.d. pulp); 45 at 25 C; 3.5 % C stage: * 4 5 min *4 v 7 days . 5.7* 4.2 7 days 11.5 * _ consistency. E stage: 0.11 x initial Kappa No. (% NaOH on o.d. pulp); 90 min at 70 *C; 10% con sistency. min '4 t l 44 - 2.0 * No residual chlorine was present after chlori nation • - - 4 » *,f Unbleached Pulp: black spruce kraft pulp ; Kappa No., 28.7. C stage: E stage: -- 3.5 % consistency. 3.2% NaOH on o.d. pulp ; 70 *C; 10% consistency. We also compared the bleaching of Douglas fir kraft pulp and balsam fir kraft pulp both made at 30 Kappa number. On average, Douglas - - - fir fibres are thick walled ( average wall thick ness 3.2 |im [13]). Balsam fir fibres , on average, are thin ( average wall thickness 2.1 - . - ) Uni [13] - If diffusion is rate controlling in chlorination , the Douglas fir fibres should be less extensively chlorinated than those of balsam fir Thus , after chlorination , Douglas ir fibres might be expected to contain more r unchlorinated lignin and to have a higher CE Kappa number than identically treated balsam fir fibres Table III shows that this was not the case ; the Kappa numbers of identically treated * 'mples of the two furnishes were, within exper imental error, the same. . * . - Finally , we compared the bleaching of earlywood and latewood fibres both prepared from same Douglas fir log. Earlywood fibres have lumens and thin cell walls (1.3 urn), late wood fibres have thick walls (5.3 urn ) [13]. If is a factor , the lignin in the cell - Effusion **11 a of latewood fibres should be less well chlorinat.ed. Chips from each morphological * 91011 were selectively cut with a laser and pulped to approximately the same Kappa by suitably adjusting the applied alkali The pulps thus obtained were treated *Uh identical charges of chlorine and caustic • -A «« • - Table IV. Comparison of the Bleaching of Early wood and Latewood Fibres Obtained from Douglas Fir by Kraft Pulping Fibre Type Kappa Number Initial After CE Earlywood Latewood 29.1 30.4 - 5.2 5.2 0.2 x initial Kappa no. (% Cl on o.d. pulp ); 45 min at 25 *C; 3.5 % consis tency. 0.11 x initial Kappa no (% NaOH on o.d. pulp); 90 min at 70*C; 10% con sistency. C stage: - - . E stage: - The diffusion theories cannot explain all these observations, and thus another hypothesis is needed to answer the original questions which are restated here: (i ) why does some chlorinated lignin refuse to dissolve in alkali? ( ii ) why , once it has been treated with alkali , does it behave towards chlorine as though it were normal kraft residual lignin? ( iii ) why is there a change from a rapid to a slow chlorination phase? The only satisfactory response to these questions, in view of the observations made, seems to be that during chlorination , lignin becomes chemically deactivated to attack by chlorine through the formation of 'blocking groups ' which are relatively stable under the conditions of chlorination , but which are labile in alkali . 73 £ What is the Nature of the 'Blocking Groups * ? Our recent work on the alkaline extraction ie [14] has indicated that large amounts of fcum carbonate as well as sodium chloride are formed during the hydrolysis of chlorinated Thus, there are indications that chloriV ). nated pulp contains labile carboxyl groups which pulp. nated t We have also observed that, when chlori pulp6 are heated , C02 is evolved (Table may be decomposed to C0? or carbonate by the action of heat or dilute alkali. Table V. Evolution of C when Heated 02 from Chlorinated Pulp Carbon Dioxide Evolved , £ Analytical Method Temp • •c $ % on o.d. pulp mole/kg Gas Chromatography 125 0. 15 0.034 Water Displacement 100 0.12 0.027 Unbleached pulp: • ^- black spruce kraft pulp: Kappa No• » 30.9 6.2% Cl2 on o.d. pulp; 45 min at 25 C; 3.5% consistency. C stage: # first With these reactions in mind , we are put t forward two mechanistic schemes which are speculative but might explain all the observa .- tions discussed above (Figure 3) The suggests that the attack of chlorine on certain phenylpropane units may be inhibited by side chain fragments displaced from neighbouring <> < i The second suggests that the oxidised remnants of aromatic rings are the inhibiting £ SCMCMf t OH M H H -C- -i C M C O l» g OH I L'W . r. d O C OH * • • Cl7 i «« t ct i 11 r% - c - o- L m • c OH u? Cl7 tow Further Ondatlon •i Product » Stock mg Group SCHEMf }, .. * Cl j f » «t o Cl, i •l o w . ly 5 ?C, Cl 0 -- --- 1. Chloro o benzoquinones Chloro o quinones are thought to form when unbleached pulps are chlorinated [15, 16,21] and are the likely source of the orange colour in the pulp. Tetrachloro o benzoquinone (I ) is quite stable under chlorination conditions (see Experimental section) but it is possible that less highly chlorinated o quinones might be more reactive and undergo ring opening to form muconic acid6 [23, 24]. Nonetheless, the pre vailing orange colour of chlorinated pulps is a good indication that many chloroquinones per sist*, and they must therefore be candidate ' blocking groups'. Table VI shows that tetrachloro o benzo quinone was indeed decomposed under the con ditions of an alkaline extraction stage yielding about 2 moles of chloride and 0.4 moles of carbonate per mole of chloroquinone. Under the conditions of hot water treatment [17], only one chlorine atom was released per molecule. -- Cl ; Further 0> MJ « IIOO •« O w Product* - - -- - - 2. Chloromuconic acids Chloro muconic acids are formed [18, 20] when chloro o benzoquinones are treated with peroxide or peracids (Eq. 1); however, it is not known v/ith certainty that this reaction occurs under chlorination conditions [21]. Gess and Dence [22] have reported the isolation of a fi trichloromethylmuconic acid from chlorination of . creosol, but the characterization was not com plete Although the existence of chloromuconic acids in chlorinated pulp is not fully proven, they are certainly candidate 'blocking groups'. Just like chlorinated pulp, tetrachloromuconic acid decomposes yielding HC1 and C02 when heated in the dry state [18], and it gives carbonate and chloride when heated in water or dilute alkali (Table VI ). -- - . 0 Cl ,t+ N OM structures. In this paper only the second alternative will be discussed further. Chloro o benzoquinones and chloromuconic acids are likely to be present in chlorinated A combination of the two might satisfy pulp. the requirements for the production of C02 and HC1, and each might produce, after hydrolysis, a readily oxidisable fragment. HO Q Sim; Mrs Group . Oxidised aide chains or the oxidised Kiqure 3 remnants of aromatic inhibit chlorination lsbi 1 e to aika li. lings mav and yet be • Gierer «.nd Sundholm isolated five different chloro o quinones after l i g n i n model compounds were treated w i t h an excess of chlorine water [ 25 ] . -- Table VI. Chloride an . Carbonate from Model Compounds and from Pulp Substance - Alkaline extraction Hot water treatment Chloride, Chloride, mole % Carbonate , mole % 111 51 80 mole % Carbonate, mole % 195 305 0.16* 38 63 0.09* -- Tetrachloro o benzoquinone Tetrachloromuconic acid Chlorinated kraft pulp 236 0.09* 0.06 * * expressed as mole/kg Unbleached pulp: C stage: black spruce kraft pulp ? Kappa No• 30.9 6.2% Cl2 on o.d. pulp; 45 min at 25 *C; 3.5% • consistency. Hot water Treatment stage (Wh ): 60 min at 90 C; model compounds, 0.0025 moles/L? pulp, 1 % consistency. E stage: 0.075 moles NaOH/L; 90 min at 70 C; model i* compounds , 0.0025 moles/L; pulp, 1 % consistency - # - # - # Cl /C * ! 0 ;P :**. : I» Cl Cl - l ci HOOR H20 CINC/Cs Cl . u 91c/OH A c , \o - ROH .f (1 ) - - - •n t It is evident from Table VI that the two model compounds chosen gave too much chloride and not enough carbonate compared to pulp. - Tetrachloro compounds were used as model com pounds because of their ready availability. In chlorinated lignin , di and trichloro compounds would doubtless predominate as they do in the chlorination of creosol [22] and one would therefore expect to obtain a lower chloride to carbonate ratio from pulp than from these model - - compounds. Carboxylic Acids and their Precursors Are They Blocking Groups7 - is one of the few acidic oxidants which can decompose carboxylic groups yielding C0? It is also one of the few r «?ag © nta capable of producing a semi bleached kraft pulp In a single stage. [Unbleached kraft Pulp reaches a high brightness in the Kappa . - - ^ Table VII. Bleaching Kraft Pulp by the Sequences CW D and CED ) , - permanganate - ^ Kappa No. Na.CX , formed by Treatment alkaline treatment * Pre-D Post D mole/kg - Whereas chloroquinones and chloromuconic acids behave like pulp in yielding chloride and carbonate when treated with alkali , this certainly does not prove that they are neces sarily the blocking groups or even that there are any blocking groups , Some well devised experiments will be needed to prove or refute the hypothesis put forward. However , there are two observations which are consistent with the 'blocking group' theory. Potassium treatment removes acidic groups from chloroli'nin [14, 17] without removing the chloroligmn itself. As can be seen in Table VII , increasing the water temperature did not change the Kappa number measured prior to the D stage, however it did improve the delignifica tion in D i * When we examined the amount of labile carboxyl groups present in the CW pulps (as indicated by the amount of sodium carbonate formed when the pulp was given an Pre D Stage — — - water *• - permanganate suggests that if carboxylic groups could be broken down during chlorination then semi bleached pulps might be obtained directly. The second piece of evidence comes from the hot water treatment of chlorinated pulps. Hot OH 0 R = H or CH3. CO number test as a result of complete delignifica tion by permanganate], The performance of CW 25 CW70 CE 00 11.7 5.5 4.8 3.6 1.2 11.6 11.6 4.9 0.088 0.068 0.058 - * Na COj formed if the D stage is replaced by an -^ E stage * assumed to be zero Unbleached pulp: - C stage: - Hot water treatment stage (Wh ): - E stage: - D stage: . . black spruce kraft pulp Kappa no• * 28.1. 5.62 % Cl on o.d pulp ; 45 2 min at 25 * C; 3.5 % con . sistency. - 60 min ; 10% consistency ; subscript denotes tempera - ture. .. 3.09% NaOH on o d pulp; 90 min at 70*C; 10% con s latency. 1.25% CIO on o d. pulp ; 3 h at 6 t> * C; 1 0 % con s istency . . - 75 - alkaline extraction) we observed that the hot water stage definitely removes some of these groups (Table VII ). The amount of the carbonate formed from labile carboxyl groups roughly parallels the Kappa number after the D stage. This is leading us to the conclusion that the importance of the extraction stage may not be in removing chlorinated lignin fragments but rather in breaking down certain carboxylic acids or chloroquinones which are produced during chlorination and which are a hindrance to further oxidation. - *• CONCLUDING REMARKS Boundary layer diffusion control of chlori nation cannot explain why a second chlorination can only remove a part and not all of the residual lignin remaining after chlorination and extraction. The chloro lignin barrier theory cannot explain why residual lignin in CE pulp has a substantial chlorine content. Neither can it explain the equal chlorination rates of thin walled and thick walled fibres, nor the fact that a C stage has a limiting CE Kappa number even when considerable time is allowed for dif - - • - # Measurement of CO ? Evolved from Chlorinated Pulp when Heated In a water displacement method , a known weight of chlorinated pulp fibres which had been dried over P2 s was placec in a melting point capillary tube and the capillary tube was placed in an apparatus as shown in Figure 4. The amount of C02 evolved when the temperature was raised to, and maintained at, 100 "C was measured from the difference in the volume of liquid displaced when water and then sodium hydroxide solution occupied the vial. * ° t* . Water or NaOH solution Thermometer — or - . fusion i . « - - - - ed in laboratory bombs under the following con ditions: sulfidity , 30%; effective alkali , 18% H factor: balsam fir, 2700 and 2800; Douglas fir, 2100 and 2250. The resulting Kappa numbers were: Balsam fir, 30.5 and 29.1 ; Douglas fir 31.5 and 29.7. ». CO, bubble . Septum — Displaced liquid drop if Our alternative explanation suggests that chemical ’ blocking groups' may inhibit chlorina .* ion in adjoining parts of the lignin macro molecule and thus produce residual lignin Melting point capillary tube a 11 a which reacts only very slowly with chlorine. These blocking groups must be labile to alkaline attack because an alkaline treatment is able to Heating block of melting point apparatus « * restore the rapid delignification rate which is characteristic of unbleached kraft lignin . Using the formation of sodium carbonate and chloride in E stage liquor as an indicator of chlorolignin chemistry, we have selected chloro quinones and chlorocarboxylic acids as candidate ' blocking groups *. .J ’ < • *< i - EXPERIMENTAL SECTION - • •• 4 Pulping of Earlywood and Latewood Douglas Fir Samples Laser cut samples of earlywood and late wood were kindly donated by E.K. Andrews and R.C Eckert , Weyerhaeuser Co. The samples were cooked in laboratory bombs under the following conditions: Sulphidity, 30% ; liquor to wood , ratio 7.0 L/kg ; max. pulping temperature , 170* C; time to temperature , 90 min ; H factor , 1668 ; effective alkali , 21.36% on o.d. wood for Mywood, 19.37% for latewood - . - - . Pulping of Douglas Fir and Talsam Fir Samples Douglas fir and balsam fir chips were cook 76 - Chlorinated pulp fibre Figure 4. Apparatus used to measure 00? evolved when chlorinated pulp is heated . In a gas chromatographic method , a known weight of chlorinated pulp fibres (0.5 to 1.0 g) were placed in a vial sealed with a septum. The vial was heated for 20 minutes at 125 *C and the gas space was sampled. This sample (0.2 mL) was injected into a HP 5720A gas chromatograph equipped with a thermal conductivity detector. A molecular sieve column (Linde 5A , 120 x 0.64 cm id ) was used with a helium flow rate of 40 mL/min. The column oven temperature was 180 * C. -- Chlorination of Tetrachoro o Benzoquinone (Kodak , Tetrachloro o benzoqumone m.p • 133 135* , 1.003g) was dissolved in methylene dichloride (25 mL) and chlorine water (25mL, 6g Clj/L) was added , The mixture was stored in a glass stoppered flask in the dark at 25 * C for 48 hours. The layers were then sep irated and the CH 2 CI 2 Layer was washed with two 10 mL portions - -- deionized water. The combined aqueous extract and washings were evaporated and yielded only 2.1 mg of a buff colored solid. of The CH 2 Cl? layer was evaporated and yielded the starting material (m.p. 130 132 * , 0.984g ) a recovery of 98.1 %. Evidently tetrachlor - — - - o benzoquinone is quite stable to chlorine under normal conditons. Had ring opening reactions occurred , then large quantities of chloromuconic acids would have appeared in the aqueous extract [18]. - Preparation of Tetrachloromuconic Acid Tetrachloromuconic acid was prepared by oxidising tetrachloro o benzoquinone (9g ) with a mixture of acetic anhydride, sulphuric acid and 30% hydrogen peroxide as described by Shulgin [19]. The reaction was slow, but after 2 hours the white product began to crystallize. After 3 days , 8.9g of product was filtered off. Shulgin * s method yields a product which is con taminated with sulphuric acid . The crude tetrachloromuconic acid was dis solved in ether (10 mL) whereupon 1 to 2 mL of sulphuric acid separated as a dense phase. Benzene (40 mL ) was added and more sulphuric acid separated. The upper layer was removed and allowed to evaporate slowly in a fumehood. Shiny white crystals of tetrachloromuconic acid (3.0 g) were deposited , mp: 149 154 * (dec • 9 gas evolution ). Lit. 148* [20], 156.7* [18] . -- - - * - Bleaching Procedures Details of the bleaching procedures are given in previous publications [14, 17] . Hot water treatment and alkaline extraction of model compounds and small quantities of pulp were done in 50 mL polyethylene bottles The CO , produced - . during hot water treatment was stripped off after the reaction time was completed . This was done by passing C 02 free nitrogen through the hot water treatment effluent and then passing the exiting gas through sodium hydroxide solu tion. - - - - ACKNOWLEDGEMENTS We are grateful to Dow Chemical Canada Ltd. for generous financial support. We thank J. Waugh , H. Nugent and P. Wong for careful experimental work and F.J. McPhee for preparing some of the kraft pulps. We a. e grateful also to J.M. MacLeod for suggesting Douglas fir earlywood and latewood as sources of fibres with widely different wall thicknesses , to E. K. Andrews and R.C. Eckert, Weyerhaeuser Co., for the gift of the laser cut Douglas fir earlywood and latewood samples , and to N. Liebergott for reviewing the manuscript. * - REFERENCES . Dence, C. and Sarkanen, K• Tappi • 87 (1960). 2. Chapnerkar , V.D. PhD Thesis , 196. (U. of Fla . ), University Microfilms , Ann Arbor , Mich. 3. Ackert , J.E., Koch , D.D. and Edwarls, L.L • Tappi , 58 (10):141 ( 1975 ). 1 4. 5. determined by ion chromatography on a were Dionex model 2010 ion chromatograph. Organically bound chlorine was analysed by Guelph Chemical Labora tories , - Ontari o in a proced ure wherei n the ® ample was ashed and the libera ted hydrog en chlor ide measur ed as silver chlori de after Absor ption in silve r nitrat e solut ion. # Paterson , A.J. and Kerekes , R.J., Tappi , 62 (5 ):114 (1984). Hatch , R.S. in "The Bleaching of Pulp ** , TAPPI monograph 510, N.Y. (1953), p.18 6. Karter and ( 1971 ). 7. du Manoir , J • TR 25 (1980). 8. Ackert, J.E • 9 Edwards , L.L. and Norrstrom , H , Pulp & Paper Canada , 76 (2 ):97 (1975 ). 9. Macas , T.S., J. Pulp Paper Sci., 10 (5): J 108 (1984 ). 10 . Giertz, H.W., Tappi , 34 (5 ):209 (1951 ). 11 . Rapson , W H. and Anderson , C.B., 49 (8), 329 (1966) (see Table V ). 12. Kuang , S. J., Saka , S. and Goring , D.A.I # J . Wood Chem. Technol. 4 (2 ), 163 (1984 ).• 13. Scallan , A.M. and Green , H.V., Wood and Fiber, 5 (4):323 ( 1974). 14. Berry , R.M. and Fleming , B.I., Inti. Pulp Bleaching Conf., Quebec City, 1985, Pre prints, p. 93. Bobalek , 0 Tappi, 54 (11 ):1882 Trans. Tech . Sect • 9 6 (2 ) . . Tappi , - - 15. White , E.B., Swartz, J.N., Peniston , Q.P •9 McCarthy , J.L. and Hibbert, H., Paper Trade J., 113 ( 24):33 ( 1941 ). 16. Ivancic, A and Rydholm , S.A., Svensk Pap perstidn , 62 (16 ):554 ( 1959 ) Analyses Used Kappa number was measured by CPPA standard method , G 18. Carbonate and chloride . 43 (1 ): . . . - 17. Berry , R.M. and Fleming , B. I • 0 Proceedings TAPPI Pulping Conference, San Francisco (1984 ), p. 169. 18. Karrer , P. and Testa , E • 9 Acta • 32 (3):1019 (1949). H e 1 v. Ch i m. 9 19. 20. Shulgin , A.T., U.S. Pat. 3, 153,669 (Oct. 20, 1964). Shulgin , ( 1964), A .T• 0 Rec. Trav. Chim * r 83:897 77 I $ -. . . Gess, J M and Dence, C• • Tappi, 54 (7): 1114 (1971). Van Buren, J. B. and Dence, C.W• 9 Tappi, 53 (12):2246 (1970). » I - Dence, C.W • in "Lignins , Occurence, Forma tion Structure and Reactions" , Sarkanen, K.V. & Ludwig, C.H • I Eds • 0 Wiley (1971), ChlO , P 414 21. ^ • *• 23. C.W • 0 24. Kempf, A.W. and (5):864 (1970). 25. Gierer , J. and Sundholm , L• 0 Svensk Papper stidn• 0 74 (11 ):345 (1971). I Dence, Tappi, 53 - I J I I- *• • - !i if . "ff. I* r. * - r * 1 ' 4 I * f .no » * » i. V * < I “t . *• * • • •1 * • \ c - . T .;\ • r .u 'l *• k 4 . / I - rjfcs# ' I • 1 . •& < 4 • . .--. • •i r i • ’;. • A e I •• / i I •• t * l * ‘. t •V # 9 .t % ^ . % •iN LH • ». * 4. ! » * - *I .. i *»> "* r: « i •4 i : r i.fit < t* a . i 4 " " J , - • 1 4 # fj • . i i , Vf »* >I • # • * ? i/: l Ifl I 1 4• i f ».•- - » * •* * c . "» r • * r. V* t opic techniques ( lH and 1 3 C nmr, e.g., DF.PT , etc ). Certain structural information has clearly been obtained. These findings will be discussed in detail. Further , becvjse of the tediousness inherent in the manipulation of aqueous samples , we ha /e developed methodology rendering these lignosul phonates organic solvent soluble (4,5). Figure 1 shows the resolution of the paucidisperse compo nents on hplc silica columns. We shall discuss our findings regarding the structures of these materials and their relationship to the original lignin macromolecule. srectr ' . SULPHITE PROMOTED DELIGNIFICATION HAROLD BRADFORD and NORMAN G. LEWIS - PULP AND PAPER RESEARCH INSTITUTE OF CANADA 3420 UNIVERSITY STREET MONTREAL, QUEBEC - H 3A 2A7 and ALEC M . BIALSKI and CORINNE E. LUTHE TEMBEC INC • » TEMISCAMING , QUEBEC JOZ 3 R 0 1.0 - Approximately 80% of the soluble lignosulpho nates ( from conifers) have been described as an homologous series of sulphonated lignins having identical repeating units. The remainder (ca. 20% ) exists as a group of poorly define lower molecular weight materials, currently named "he milignins " (1 ). Precise structural data for these aforementioned homologues has been presen ted , but remains a controversial issue due to a lack of convincing published evidence. It should be emphasised that most or the separations of these lignin derived substances were carried out using Sephadex column chromato a process known to result in limited graphy resolution of mixtures. Thus, in the light of these extra ordinary findings, and as a first measure, we developed methodology which established the following: ( i ) aqueous high performance liquid chromato graphy of soluble 1 ignosulphonates which resulted in a much improved resolution of these mixtures (2) (ii) that the hplc separation of these ligno sulphonates was based mainly upon molecu lar size differences ( 3) ( iii ) during sulphite pulping, two main classes of sulphonated lignins were removed , i. e. , paucidisperse ( M w < 3 , 300) and polydisperse ( > 3 ,300) (2, 3 ) ( iv ) only paucidisperse (i.e • 9 resolvable, low molecular weight lignins) were removed during the early stages of delignifica tion ( 30% lignin removal). Beyond this point, only widely polydisperse materials were solubilised (4) ( v ) prolonged hydrolysis of these polydis perse substances did not result in the genesis of either (a ) the single repeat ing unit reported to occur or ( b) addi tional paucidisperse material (4 ). These aqueous lignosulphonates ( both pauci and polydisperse) have been analysed by standard - ~E 0.8 c o GO - *< 0.6 © CJ C JS 0.4 o O < (A > 02 3 - - 0.0 - 4 6 10 8 ( Elution Volume mL ) - . Figure 1 Mw - - - - - - -- Hplc separation of paucidisperse coni ferous, fully methylated , lignin sul phonates. Elution details: Waters porasil column , eluted with 0.25 % CH 30H in CH Cl . Flow » 1 mL/min. - - 12 ^ ^ Our conclusions pertaining to the validity of Forss ' model for coniferous lignin and hemi lig nin will also be presented. In addition, the thermally induced polymeri sation of spent sulphite liquor components was also investigated (6). Consequently , a more detailed understanding of the role of the poly and pauci disperse 1 ignosulphonates and the car - - bohydrates during thermosetting has now been . achieved This detailed knowledge has direct applicability to the use of spent sulphite liquor as a composite wood adhesive. REFERENCES 1. - FORSS , K. and FREMER , K . E., J. Appl. Polym. Sci., Appl . Polym. Symp., 37: 531 47 ( 1983), and references therein - LEWIS, N.G., GORING , D.A.I. and WONG, A., Can. J. Chem., 61: 416 18 (1983) LEWIS, N.G. and YEAN, W.Q., J. Chromatogr. (in press) FONG , J.L., LEWIS, N.G. and LtJTHE, C.E., Can. J. Chem. (in press) PADMAPRIYA , A.A., .JUST, G. and LEWIS, N.G., Synthetic Communications (in press) BIALSKI, A.M., BRADFORD, H., LEWIS, N.G. and LUTHE, C.E., J. Appl. Polym. Sci. (in press) . 2 - . 3 4. . 5 6. I % r. i m t i f c • < « # t .• 71.V' i i I K *« * • . _ r •» v * <* « • •\ t v *.‘ 4 r r - * r .. ^ I."’* J J » t ? i - ‘ * > - •: . * *. ~T •• . *» # - . ccr * ? i \ 1 n • :ro •,a *• » ‘ . /• 7 - K i Ol V V *•:4 r •. t ri . l .f - * ^ • 4 I r i i I. • * < c #9 I I 4 1« p l*« - Hi *' f I - i i if V * # * I f i r * • % (ri i « # ! • •> / 9 r * .* # 4 % * D I METHODE DE THIOACIDOLYSE DES LIGNINES : NOUVELLE " CARACTERISATION DES ALKYL-ARYL ETHERS. C. LAPIERRE, C. ROLANDO b MC et B. MONTIES a : Laboratoire de Biochimie (INRA), INA.PG, 78850 THIVERVAL GRIGNON, FRANCE. - b : Laboratoire de Chimie , E.N.S• # 24 rue Lhomond , 75231 PARIS, FRANCE. I •• • ABSTRACT Part of this work has been previously published - Fiqure (1 3). This paper reports our present knowledge about _ 1. Degradation des structures alkyl-aryl ethers non condensees par thioacidolyse. •, - lignin thioacidolysis (solvolysis in dioxane ethanethiol 9/1 , 0. . f* N BF -j etherate) and confirms its analytical > Le melange de produits de degradation monomeriques interest. i • obtenus est done beaucoup plus simple que celui de I ’aci - dolyse (figure 2). La reaction n'est pas st6r6ospecifique : - A partir d'un dimere alkyl aryi ether threo ou erythro, L'acidolyse selon Lundquist (4) coupe spedfiquement on obtient un melange des diastereoisomeres monomeriques. les liaisons alhyl- iryl ethers des lignines. De plus , les Des etudes cinetiques realisees sur lignines ou sur residu produits monomeriques issus de cette degradation pr£ parietal ont roontre que la duree de 4 heures de reaction sentent le sguelette phenylpropane C..-C.. caracteristique est optimale. Les resultats compares obtenus pour des echantillons de lignines de bois moulu (M W L) sont m - des unites constitutives des lignines. Cependant , l'aci - - dolyse a deux inconvenients : d'une part , les rendements diques dans le tableau 1. Ils sont exprimes en pourcentage en produits de degradation monomeriques sont faibles en ponderal equivalent a celui des diastereoisomeres raison de reactions de condensation catalysees par les p hydroxyphenyles (H), gualacyles (G) ou syringyles (S) acides utilises en milieu aqueux ; d'autre part le nombre obtenus par thioacidolyse. - Sieve de produits d'acidolyse formes en rend la separation delicate. Pour conserver les avantages de l'acidolyse (specific te de degradation et structure C ! ^- ^ C M W L de : Peuplier des produits Pin (bois de reaction) Pin (bois oppose) monomeriques obtenus), nous avons tente de remedier A ces deux limitations. Dans ce but, nous avons utilise 1'ethe Monomeres % rate de trifuorure de bore et 1'ethanethiol (EtSlI) pour - total - H// - . Le ^ etherate G - EtSH) est en effet un reactif 12.4 S efficace de coupure des liaisons ethers en conditions douces (5). S G La thioacidolyse (solvolyse en milieu dioxanne - - ethanethiol, 9/1 , 0.2 N BF etherate, 4 heures a 100 C) ° 3 permet effectivement de degrader - les structures alkyl aryl ethers non condensees des lignines en produits T A T A T 1.7 4.6 traces 0.46 16.1 11.8 21.7 13.9 27.8 H deqrader les lignines dans le dioxanne anhydre systeme ( BF A G 9.4 21.0 traces 0.8 traces 0.30 21.8 37.1 13.5 27.1 13.9 28.6 0.76 1.30 0.14 0.04 0.01 0.21 0.02 Tableau 1.Resultats compares des acidoiyses A et des . thioacidolyses T de lignines de bois moulu •nonomeriques thioethylphenylpropanes (figure l). I I I ei I a I II b su Z o o LU LLJ - UJ 8 Q I . f * V TEMPS figure 2 Chroma toqrarnnes en phase qazeuse des produits monomeres a) de l ’ acidolyse (indiguds par une fldche) et b) trimethyl silyies gualacyles (G) et syringyles (S), issus de la thioacidolyse d'une Ugnine de Peuplier te. i :etalon int.) 81 Le rendement total de thioacidolyse est environ le uble de celui de l'acidolyse. L'aroelioration du ren - ment est plus forte pour les unites S et H que pour les it£s G. La thioacidolyse donne done un reflet plus a a 3ele de la quantity et de la composition des structures lvolys£es que l'acidolyse. J* La thioacidolyse a permis de confirmer 1'heterogeneity N1 -ucturale des fractions de lignines extraites successi- PI lent de bois de Peupliers, par des methodes douces. ai un nombre eieve d'echantillons, issus de Peupliers ou K: Bie , elle a permis la raise en evidence d'une forte c\ relation lineaire positive entre 1? rapport S/G et la Tie (S + G) des diastereoisomeres syringyles et guala pf - ;s. Plus la teneur en unites syringyles est forte , plus - - AJ et al (6). L'optimisation de certains parametres ph rimentaux et 1'analyse des dimeres de thioacidolyse co titueront la suite de ce travail. ad liaisons alkyl aryl ethers non condensees sont fre ites. Ce resultat Concorde avec celui obtenu par ;ser an li SER , W.G• 0 C.A . BARNETT et Y. SANO . Classification ignins with different genetic and industrial tins, / op " A - Polymer Symp 37 ; 441 460 ( 1983). r ec beo wha oth to pro 6 pe AHO wh I Hq cle con add the - 1 man; I Le rendement total de thioacidolyse est environ le double de celui de 1‘ acidolyse. L‘ aroelioration du ren - dement est plus forte pour les unites S et H que pour les unites G. La thioacidolyse donne done un reflet plus fidele de la quantity et de la composition des structures solvolysEes que 1‘ acidolyse. I La thioacidolyse a permis de confirmer 1'hEtErogenEitE structurale des fractions de lignines extraites successivement de bois de Peupliers, par des methodes douces. Sur un nombre ElevE d'echantillons, issus de Peupliers ou de BlE , elle a permis la raise en Evidence d'une forte I correlation linEaire positive entre 1 5 rapport S/G et la * somme (S + G) des diastEreoisomeres syringyles et guala - cyles. Plus la teneur en unites syringyles est forte , plus - - les liaisons alkyl aryl others non condensees sont fre quentes. Ce rEsultat Concorde avec celui obtenu par Glasser et al (6). L'optimisation de certains paramEtres expErimentaux et 1'analyse des dimeres de thioacidolyse constitueront la suite de ce travail. REFERENCES 1. LAPIFRRE, C•• B. MONTIES et C. ROLANDO. Structure des - liqnines : Evaluation de liaisons arylglycErol aryl Ethers par thioacidolyse. C.R , Acad Sci Ser III 299 - ( 11 ) : 441 444 (1984). 2. LAPIERRE, C• B. MONTIES et C. ROLANDO. Thioacidolysis # of lignins : comparison with acidolysis. J Wood Chem - Techno1 5 (2) : 277 292 (1985). 3. LAPIERRE, C., B. MONTIES et C. ROLANDO. Preparative - thioacidolysis of spruce lignin : isolation and iden tification of main monomeric products. Holzforschung : accepte pour publication ( 1985). - 4 . LUND^UIST , K. Low molecular weight lignin hydrolysis - products. Appl Polymer Symp 28 : 1393 1407 (1976). . NODE. M • * H. MORI et E. FUJITA . Demethylai on of - aliphatic methyl ether with a thiol and boron tri floor ie. J Chem Soc Perkin Trans I : 2237- 2240 ( 1976). r* . 6 GLASSER , W.G• # C.A. BARNETT et Y. SANO . Classification of lignins with different genetic and industrial > rl 32 - .ns. r pi . Polymer fymp 37 : 441 460 ( 1983). - fl aryl ether quinono methides are not the only quinone methides which can form under pulping conditions. Indeed , any free pheno 1 ic unit with an a- leaving group (OH. OAr . or OR ) can form quinone methides 4 . We wished to know if these quinone methides can also trap AHQ or anthranol and . if 60. how this affects the AQ cycle and the reaction pathways of these other units. The main objective of the work described in this paper was to determine if quinone methides from B C linked structures react with AHQ and anthranol and to characterise any adducts formed. Only the phenyicoumaran structure is considered here , although studies on B Cl and other B -C linked models are also in progress in our labora tories. - REACTIONS OF PHENYLCOUMA ; AN LIGNIN MODEL QUINONE METHIDES WITH AHQ/ ANTHRANOL JOHN RALPH NEW ZEALAND FOREST RESEARCH INSTITUTE. PRIVATE BAG. ROTORUA. NEW ZEALAND , and RICHARD M. EDE . CHEMISTRY DEPARTMENT, UNIVERSITY OF WAIKATO PRIVATE BAG HAMILTON , NEW ZEALAND. . - - ABSTRACT Quinone methides prepared in 6 itu from phenyIcoumaran lignin models , which did not contain a 7 hydroxymothyl group , readily formed RESULTS AND DISCUSSION addition products with anthranol but not with Model 8 anthrahydroquino ne ( AHQ). For phenyIcoumaran lignin models containing the hydroxymethyl The most readily available phenyIcoumaran raodelr are dehydrodiisoeug eno 1 l , and its group the retro- aldol reaction ( liberating formaldehyde) was so facile and rapid under the conditions used that stilbene formation from the quinone raerhide took precedence over adduct forma tion. reduction product dihydrodehydrod ii 6 oeugeno 1 2 (Fig. 1). Use of 2 rather than 1 removes the confpl ication of further reactions of the vinyl - sideehain which are not characteristic of the phenyIcoumaran moiety. Lignin model , phenyIcoumaran. quinone methide. anthraquinone. anthranol KEYWORDS: INTRODUCTION A great deal of activity has been directed toward the 6 tudy of the reactions of AHQ and anthranol with fl - aryl ether quinone methides. It is primarily the reactions of these lignin units under a l ka l ine/ additive pulping conditions which are responsible for the accelerated cleavage of the lignin macromolecule in , for example. AQ pulping . Loss of AQ from the pulping cycle has also received considerable attention 1 , We have been interested in ascertaining how and to what degree , the reactions of additives with other lignin unit quinone methides contribute to their overall function in the pulping Process . Although there is considerable ® PecuI at ion 2 as to whether adducts between AHQ ( or anthranol. a reduction product of AQ which is also present in alkaline cooking iiquors) are intermediates in the catalytic Cleavage of B ether bonds under alkaline conditions there is no question that such adduct8 are readily formed 3: furthermore rbeir formation may not be as reversible as Wany tend to believe. . . - . *2 CH3 CHKH-CH3 CH3 CHjCHjCHg 3 CH H H U CH2OAC H Fig. 1. ^ PhenyIcoumaran and ‘ opened * PhenyIcoumaran models used . Although the use of these models is valuable in developing methods for the study of adduct formation, it is preferable to use a more representative model 6 uch as 3 (Fig . 1) which possesses the 7 hydroxymethyl group present in most lignin 6 idechains . The presence of this group markedly influences the course of important reactions . A model representing a ' ring opened * phenyIcoumaran ( which could not ce cyclise) was also required in our studies. Model 5 (Fig . 1). in which the B ring phenolic group is methylated , was prepared using essentially the method of Brunow and Lundqulst 6. - - 83 Anthr anol and AHQ Adducts with B- 5 Models - Alpha aryl ethers such a6 compoun ds 1- 4 4 (Fig X) are known to ( reversi bly) generat e quinone methid es at a signifi cant rate even at 10°C in 1M NaOtl (Fig. 3 ). Theref ore , attempt s to form adduct6 from quinone methide s 7 9 (Fig. 2) were made by additio n of models 1 to 4 directl y to soluti ons of anthran ol or AHQ in base. These reacti ons gave product s as summar ised in Table 1. - phenoli c diacety lated model 6 in base , As there was no possib ility of quinone methid e l ] reverti ng back to a phenylc oumaran by an intern al cyclisa tion the yield (Table 1) of adduct was sub6 tantia 1 ly higher from model 6 than from the true phenylc oumaran s 1 4. . - TABLE 1 Approxi mate yield data for adduct reacti ons. Condit ions: 2 eq anthra nol or AHQ ; 1 M NaOH ( except 0.3 M for 4 to minimis e hydroly sis of the 7- OAc group ); 50°C; 1 hr ( 15 min for 6 ). Model Anthran ol Adduct # S/ M * * Stil bene 2 70(97: 3) 70 3 4 6 50(90:10) *90(75:25) 30 30 0 50 1 f 8 _ 3 CH 7' CH20H 9«. CH Ac 10 CH2OH CH20AC H Fig. 2. ^ * ** CH3 CH3 AHQ 0 - Adduct S/ M Sti berii 100 0 0 0 0 0 0 0 0 0 100 100 0 IOC Ratio of erythro: threo isomers ( in bracket determi ned from H I NMR. 75\ yield after flash chromat ography. Startin g materia l. Despite the high stereos electiv ity observe d for threo adduct 6 from B ether quinone methide s (e.g. 12) both adduct Quinone methide s . - . . CH30 isomer s can be detecte d from attack of anthran ol on any of the B - C5 quinone methide s. Figure 5 and Table 1. R *1 R? H H Ac Ac H H H Ac Ac CH3 Ac 17 CH3 CH3 CHpOH CH2OH OCH3 10 CHpOAc OH 19 CH2OAC Vi 15 16 CH3 g R=H b R'- OH OCHJ- •1 . 3. Reactio ns of phenylc oumatan s. Fig Genera tion of the quinone methide 10 from the ring - opened pheny 1 couraa ran model 5 at modera te temperat ures require d the a OH to be - replace d with a better leaving group , Attempt s to form the a- btomide of 5 using 1 TMSBr were unsucc essful due to spontane ous loss of formal dehyde, and format ion of stilbe ne 13 from the bromid e. However , the require d quinone methid e n was obtain ed in situ from the free 84 Fig. 4. Adduct st ructure s. - The B C5 adducts 14 -1? ( Fig. 4 ) like the * -9 B - aryl ether adducts 1.8 . have fascina ting NMR charact er i stics due to their confor mation s in solutio n. In the erythro isomer of 1_? ( which is analogo us to the ‘ threo ' isomer in B - ether adducts because of the way the groups are assigne d ) the A ring is again 1.9 clearly situat ed over the nthrace nyl ring system as it eviden ced by the highly shield ed ring A methoxj and the ring A protons (Fig 5). However , the minor threo isomer is qui e unlike the * erythr < t e m p e r a t u r e. »> . a p p a r e n t f r o m Table 1. 1. 9 ,- . . s * . - .u F i g. 5. 70 60 SO J W h e r e a s anthran ol adducts form readily from t h e s e q u i n o n e raethid es. it w a s n o t p o s s i b l e t o f o r m AHQ adducts ( R ' *O H Fig. * ), p r e s u m a b l y for a combina ion of steric and ?0 electro nic reasons. It h a s b e e n noted previou sly 1 that AHQ adds less readily than h *? 0D - *c (Kij f Attempt s t o charact erise them by NMR t e c h n i q u e s (a n a l o g o u s t o those used for the 8 ethec q u i n o n e raethid es ) are in progres s S e v e r a l further i m p o r t a n t p o i n t s are . M •' tO fe ’H 30 - a n t h r a n o l t o 8 a r y l e t h e r q u i n o n e raethid es a n d it h a s a l s o b e e n s h o w n 1 that , in 9 0 M H z H~1 NMR s p e c t r a of a d d u c t s 1 9. isomer 8 of 8- ether adducts in that ring A is even more intense ly shielde d. Examina tion of the NMR s p e c t r a leads t o the postula ted conform ations s h o w n in F i g. 6. 2. competi tion studies , anthran ol ad lucts are formed in o v e r w h e l m i n g p r e f e r e n c e . Formati on of quinone methide s from phenylc oumaran s 1- 4 i 6 c l e a r l y reversi ble , but anthran ol additio n c o m p e t e s reasona bly effecti vely f o r t h e quinone methide. In a 5- minute reactio n w h e r e the quinone m e t h i d e 7 was generat ed f r o m the a iodide a t room t e m p e r a t u r e , the ratio of adduct 14a t o p h e n y l c o u m a r a n 2 was a b o u t 1 0 : 9 0. H e n c e , anthran ol attack 3. eryfhro F i g . 6. Postula ted conform ations of e r y t h r o and threo isomers of c o m p o u n d 1 9. 3 ems t o be a b o u t 1 0\ as rapid as the recyc 1 isation reactio n. In c o m p o u n d 3. with a 7 C H O H n o t even ^ . anthran ol can c o m p e t e with t h e quinone methide against the r e t r o aldol elimina tion of formald ehyde and g e n e r a t i o n of t h e 6 tilbene. T h e reactio n therefo re f o l l o w s - t h e same course as in the absence of t h e additiv e (F i g. 3)1 1. Ar This last point illustr ates the pitfall s in using inappro priatel y substit uted or derivat ised models . A c e t y l a t e d models 1.12. or a c e t y l a t e d l i g n i n itself 13.14. are f r e q u e n t l y - used t o a l l o w in situ g e n e r a t i o n of q u i n o n e raethid es a t room t e m p e r a t u r e . But t h e vvw * p r o t e c t i o n afforde d t o t h e 7 C H O H g r o u p b y £ a c e t y l a t i o n means t h a t f o r m a l d e h y d e loss b y a - Fig. 7. Major rotamer s of 8- 5 q u i n o n e raethid es . - r e t r o aldol reactio n c a n n o t c o m p e t e for the This is n o t so critica l in t h e case of 8 a r y l ether quinone methide s since q u i n o n e m e t h i d e. T h e observe d stereos electiv ity can reasona bly be attribu ted t o t h e q u i n o n e methide conform ations. Fig. 7 shows t h e t w o major rotamer s expected 1 0 for 8- 5 q u i n o n e methide s. If R is sterica liy less demandi ng than Ar (a s e x p e c t e d for R ^M e C H O H H OAc ), A would be t h e major rotarae r. Attack from the less hindere d side would lead to the erythro adduct. . ^^ . ^ For reasons that are n o t clear , these 8 5 Quinone methide s seem t o be markedl y less 8 table toward polymer isation than 8 a r y l ether Quinone methide s and a t m o d e s t concent rations , are observe d o n l y transie ntly a t room - . - - anthran ol . and possibl y AHQ. can add to quinone methide 12 (R *H) efficie ntly before the r e t r o - aldol reactio n ( t o g i v e the styryl ether ) can occur . However , in these 8 C5 models , the r e t r o - aldol reactio n entirel y dominat ed t h e - reactio n of r e p r e s e n t a t i v e quinone methide s 8 or 10 (with t h e 7- C H 7O H group ) w h e r e a s t h e adduct readily formed f r o m t h e acetyla ted quinone methide s 9 or 1 1. T h u s , reactio ns o n . a c e t y l a t e d milled wood lignin with anthran ol w h e r e adducts other t h a n 8 ether adducts appear to be observe d in t h e C 1 3 NMR s p e c t r a 1 3. 14 may n o t be r e p r e s e n t a t i v e of reactio ns of the underiv atised quinone methide s . 85 :LUSIONS 8. RAI - Adduct formation between fl C5 quinone tides and anthranol. but not AHQ. occurs lily , but only when the possibility of \a 1 dehyde elimination from the quinone lide i 6 removed . Consequently , the tivity of lignin phenylcoumaran unit6 in additive pulping is not expected to be red by the additive. Conversely , it is not cted that AQ losses can be attributed to tion6 with fl CS quinone methides. ant lie 1 nc 1 sc 388 . 9 . RAI and qu i - qui Rot So I t RENCES .ANDUCCI. L.L. and RALPH. J. Anthraquinone St M losses during alkaline pulping. Journa 1 of ood Chemistry and Technology 4(2): ^149 - 161 (1984) and references therein. 49: 10. RAU the . D.R. Electron transfer reactions )1 MMEL of 1 Jour 3(2) n pulping systems ( I): theory and pplicability to anthraquinone pulping , o urnal of Wood Chemistry and Technology . ( 1): - 1 14 (1985). 1 1 I CONCLUSIONS . J. and LANDUCCI. L.L. 8. RALPH - Adduct formation between fl C6 quinone methides and anthranol , but not AHQ , occurs adily. but only when the possibility of rmaldehyde elimination from the quinone methide is removed , Consequently , the reactivity of lignin phenylcoumaran units in soda additive pulping is not expected to be altered by the additive , Conversely , it is not expected that AQ losses can be attributed to reactions with fl - CS quinone methides. i l REFERENCES 1. LANDUCCI. L.L. and RALPH J . Anthraquinone losses during alkaline pulping. Journal of Wood Chemistry and Technology 4(2): . in pulping systems ( I): theory and applicability to anthraquinone pulping. Journal of Wood Chemistry and Technology . J ., LANDUCCI. L.L. , NICHOLSON. B.K. 9. RALPH and WILKINS. A .L. Adduct6 of anthrahydro quinone and anthranol with lignin model quinone methides. 4. Proton NMR Hindered Rotation Studies. Correlation Between Solution Conformations and X ray Crystal Structure. Journal of Organic Chemistry - 3337 3340 ( 1984). 49: - - 11. GIERER , J . The reactions of lignin during pulping. Svensk Papperstidninq 73( 18): 1 14 (1986). . L.L. and RALPH. J . Adducts of anthrahydroquinone and anthranol with lignin model quinone methides. I. Synthesis and Characterization. Journal of Organic Chemistry 47: - 3884 89 ( 1983). Journal of Wood Chemistry and Technology 3(2): 183 194 ( 1983 ). 3. LANDUCCI i Journal of Organic Chemistry 48: the conformation and isomeric composition of lignin model quinone methides by NMR. . D.R . Electron transfer reactions 6( 1 ): Isomers. 10. RALPH 2. D1 MMEL I anthrahydroquinone and anthranol with lignin model quinone methides. 3. Independent Synthesis of Threo and Krythrc . J. and ADAMS. B.R. Determination ol - 149 161 (1984) and references therein. i 3486 - 96 ( 1982). . 671 (1970) . . J . L 1 NDEBERG. O• • and NOREN , I . Alkaline delignification in the presence of anthraquinone /anthrahydsoquinone. 12. GIERER - 213 4 ( 1979). Holzforschung 33: . G.E. 4. MIKSCHE in: Chemistry of l)e 1 iqni f ica t ion with Oxygen. Ozone , and Peroxides, p. 107. Uni Publishers Co • • 13 . LANDUCCI . L.L. Formation of carbon - 1 inked - anthrone lignin and anthrahydroquinone lignin adducts. Journal of Wcod Chemistry . Japan (1980). Tokyo i and Technology 1(1): 6. LEOPOLD, B. - Aromatic keto and hydroxy prlyethers as lignin models. III. Acta H i ? mica I Scandinavica 4: . J . and LANDUCCI. L.L. Adducts of - anthrahydroquinone and anthranol with lignin model quinone methides. 9.10 l 3 c . and LUNDQU 1 ST, K. A new synthesis of model compounds for the beta 6 s t r u c t u r a l unit in l i g n i n s. Acta Chemica Scandinavica B 38( 4 ): 336 6 ( 1984). - - . J . and YOUNG. R . A. Stec eochemica 1 7. RALPH I addition reactions involving lignin model quinone methides. Journa 1 of Wood Chemistry and Technology 3(2): - » 61 181 (1983). i - 61 74 ( 1981). 14. RALPH 1623 37 (1960). 6. URUNOW , G aspects of Adducts of - - labelled anthrano 1 1 ignin adducts: examination of adduct formation and stereochemistry in the polymer . Submitted to the Journal of Wood Chemistry and Technology ( 1986). Some of the parameters that determine hydrodynamic and colloidal forces are summarized in TaDle I. HYDRODYNAMIC ASPECTS Of POLYMERS Mil INQ IN PAPFRMAKINfl THEODORUSG.M . VANDEVEN PAPRICAN McGILL UNIVERSITY . . PULP&PAPER BLDG DEPT Of CHEMISTRY 3420 UNIVERSITY STREET Table ' factors affectiny hycrodynarmc and colloidal forces forces: parameters: . hydrodynamic colloidal velocitv distribution Hamaker constant system boundaries surface charge particle size 2 shape ionic strength viscosity particle size & share diffusion constant . MONTREAL QUEBEC H3A 2A 7 polymer bridging AE TRACT " Retention of fillers and fines in papermaking is governed by several mechanisms, the most important being ( 0 the efficiency of shear - coagulation or deposition, ( II ) the strength of the bonds between fillers or fines and fibers and ( in ) the efficiency of entrapment in the forming sheet Polymeric retention aids affect these efficiencies to various degrees Shear coagulation or deposition For small particles the coagulation in turbulent flow can be described by coagulation in shear flow in which the rate of shear is replaced by an average value characteristic of the strength of the turbulent flow In case of small particles depositing on pulp fibers the rate can be estimated from nGeffR2L. ( 4/ 3 ) J KEYWORDS: Retention fines, fillers, retention aids, hydrodynamics INTRODUCTION Papermaking suspensions contain, besides the pulp fibers that are made Into a sheet of paper on the wire section of the paper machine, many more non- soluble materials, such as fines and fillers Usually It Is desirable to retain as many of these small particles as possible Increased efficiency can be achieved by adding retention aids to the papermaking furnish, usually high molecular weight cationic polyelectrolytes Their efficiency Is determined by many factors that are at present poorly or not understood In this paper we will present some remarks on the hydrodynamic aspects of papermaking, which are crucial in the retention mechanisms Selective coagulation The main task in papermaking is producing a homogeneous sheet of paper and therefore polymer bridging between fibers must be avoided as this leads to fiber floes and thus a Inhomogeneous fiber distribution On the other hand bridging between fibers and fines or fillers is very desirable Bridging between fines or fillers among themselves could be either desirable or not depending on the end use of the paper From these arguments it follows that coagulation must be extremely selective Hydrodynamic conditions favor selective coagulation( I ) in which polymers play an important role( 2 ). In general under hydrodynamic conditions aggregates of unequal sized particles are more likely to remain intact Hydrodynamic vs. colloidal forces The ratio of colloidal to hydrodynamic forces determines the efficiency of the shear coagulation process Polymers can affect this efficiency to a large extend They affect both the efficiency of aggregate formation and also of aggregate break - up Here J is the nuber of small particles captured per fiber per unit time, o is the capture efficiency, n the number of fines or fillers per unit volume, 6 efr the effective average rate of shear R the fiber radius and L the fiber length The effective average rate of shear can be estimated from the theory of Isotropic fully developped turbulence . Geff - pRe3 / 2/ dl2, where p and d are the viscosity and the density of the medium ( water ) resp and Re is the Reynolds number based on the average macroscopic fluid velocity and a characteristic dimension I ( e g the width of the slice of the headbox ). One of the mechanisms of fines retention with polymeric retention aids is to increase the value of This is possible because particles can be captured at larger distances from the fiber surface As an example we studied the deposition of titanium dioxide particles on cellophane, using the impinging jet technique( 3 ) This technique allows for a precise control of the hydrodynamic forces acting on the colloidal particles In the absence of retention aids we found that the deposition Increases from almost zero till the values characteristic for fast deposition (no energy barrier , \ ) at a critical I - 1 electrolyte concentration of about 5mM Adding a cationic polyelec trolyte of molecular weigth 500,000 resulted in an increase of the efficiency by a factor of four Part t e l e detachment After particle deposition the possibility exists that the deposited particles are removed by the shear forces Obviously one would like to retain as many particles as possible on the fibers The rate at which particles detach depends on the bond strength and the hydrodynamic forces exerted on the deposited particles An obvious way to Increase retention is to Increase the bond strength between the fines or fillers and the fibers Again high molecular cationic polyelectrolytes are ideal as they adsorp on the negatively charged surfaces of fines and 87 fibers The bond strength depends very much on the conditions under which the bond was formed as well as conditions prior to and after the formation of the bond The bond strength may depend on the fact that a particle has been stuck to a fiber before but was removed afterwards This could have changed or ruptured the polymer on its surface Also the bond strength depends on conditions during bond formation. At high shear, weak bonds do not survive and usually stronger bonds are formed at higher shear After bond formation the bond strength can either increase with time due to an increase in the number of polymer segments participating in bonding, or it can decrease with time if a competion exists for bonding sites between the bridging polymer and non- adsorbed polymer or o ,ier surface active materials In model experiments on detachment of polymer coated particles in impinging jets, we have observed both phenomena ( increasing and decreasing bond strength). The bond strength of titanium dioxide particles deposited by sedimentation on cellophane has been observed by Hubbe( 4). He found that such particles are removed typically at wall shear stresses in the range IO- IOO Pa Pelton et al ( 5 ) descibe similar results for the detachment of latex particles from glass surfaces One must bare in mind that in these experiments the bonds were formed by sedimentation and one must be careful in extrapolating these data to papermaking conditions The history effects in polymer bridging are summarized in Table II. Table II History effects in polymer bridging Particle entrapment A third mechanism for fines retention is particle entrapment in the forming sheet This mechanism is particularly important for fines particles whose dimensions are comparable to the pores of the forming sheet The average pore radius, r, in a porous sheet can be estimated from r = Re / ( 1 - ), where c is the porosity or void fraction of the sheet However there exist pores of size much smaller than the average pore radius and the smallest pore sizes will determine which f ines can pass through The entrapment of fillers and small fines ( < IOpm ) is extremely inefficient and does not contribute to retention ). Polymers are not expected to increase this efficiency very much, especially at low concentrations At higher concentrations the polymer could form a kind of web in which small particles can be trapped, similar to the large fines in the forming sheet Polymers that form gels at low concentration will be the most effective in trapping particles thic way ^ Concluding remarks 5everal fines retention mechanisms have been discussed with emphasis on the role of polymers and hydrodynamic forces It can be concluded that high molecular weigth cationic retention aids can increase retention in a variety of ways. 1 Deposition efficiency and bondstrength depend on conditions prior to bond formation ( previously broken bonds, polymer transfer, polymer rupture ) 2 Bondstrength depends on conditions of bond formation. In general stronger bonds are formed at higher shear 3 Bond strength depends on time Usually bond strength increases with time 4 Bond strength depends on conditions after bond formation The weakening of the bond due to excess freely suspended polymer is comparable to the exchange of adsorbed and non adsorbed : olymer Freely suspended polymer can be exchanged w i t h polymer engaging in bond formation, thus reducing the bond strength This is shown schematically in Fig i • i - > b u /p id r IU J * ’// / . 7/ /A Figure I Weakening of a bond L y free polymer . ' 88 References 1 . T .G.M. van de Ven and 5 G Mason, ‘Comparison of hydrodynamic and colloidal forces in paper machine headboxes", T APPI £4, 171 ( 1981 ) 2. T GM van de Ven, ‘Effects of polymer bridging on selective shear flocculation', J Colloid & Interface Sci S L 290 ( 1981 ) 3 T Dabros and T G.M van de Ven,‘A direct method for studying particle deposition onto solid surfaces', Colloid & Polymer Sci. 261 r 694 ( 1983 ) 4 MA Hubbe, 'Bonding of filler to cellulose effects of cationic retention aids', Proceedings TAPPI Paper makers Conf . - ence p 23 ( 1984) 5 R H Pelton and L H Allen, ‘The effect of some electrolytes on flocculation with a cationic polyacrylamide’, Colloid & Polymer Sci 261, 485 ( 1983 ) 6 T GM van de Ven, ‘Theoretical aspects of drainage and retention of small particles on the Fourdrimer', J Pulp & Paper Sci fl£, 57 ( 1984) _ - - ° EFFECT OF ANTHRAQUINONE ON THE ALKALINE DEGRADATION OF POLYSACCHARIDES " ADRIAN F.A. WALLIS and ROSS H. WEARNE DIVISION OF CHEMICAL AND WOOD TECHNOLOGY , CSIRO , PRIVATE BAG 10 , CLAYTON , VICTORIA 3168 , AUSTRALIA 170 C , although AC promotes random cleavage in the presence of oxygen (5 ) , the e: set of AQ and its derivatives without oxygen is less clear. Whereas Carlson and Samuelson f 5 ) found that addition of 5 % AQ (cellulose basis ) to soda cooks of cotton cellulose under nitrogen gave increased yields and slightly lower viscosities (indicative of chain cleavage ) , other studies showed that addition of 0.1 % AQ and its derivati . es (6) or tetrahydro AQ (7) gave increased yields and slightly higher viscosities. Investigations of wood derived poly saccharides require consideration of the contribution of both cellulose and hemicell uloses to the properties of the pulps , Soda AQ cooking of wood holocelluloses has beer, reported to give pulps with higher yields and higher viscosities (8) and lower zero span tensile strengths (9) than the soda controls, For wood samples , AQ addition 'o soda cooks of spruce caused reductions in pulp viscosities (10), whereas no change was not in the viscositie of soda AQ pulps fre black spruce within the range 0.1 0.5% AQ addition ( 11). Because of the contradictory nature of the above observations , we undertook an investigation of the effect of AQ on the alkaline degradation of cotton cellulose and P. radiata wood . - * - ABSTRACT cotton cellulose at 170 C gave higher yields Soda anthraquinone (AQ) digestions of ° of residual cellulose with increased carboxyl contents and lower viscosities than soda digestions. However , when reduced AQ (as 9 ,10 diacetoxy anthracene (DAA)) was added to soda cooks of cotton cellulose containing sodium dithionite , no change in yield and carboxyl content and only a small viscosity decrease early in the cook was observed. Soda and soda AQ pulping of P. radiata wood gave pulps which after chlorite delignification had lower zero span tensile indexes and slightly lower viscosities with increasing AQ charge. The data suggest that AQ promotes the scission of glucosidic bonds of cellulose under alkaline pulping conditions. - - - INTRODUCTION The addition of catalytic amounts of AQ and its derivatives to alkaline wood pulping systems results in higher pulp yields and increased rates of delignification. The higher pulp yields are due in part to the ability of AQ to oxidize the terminal aldehyde groups of polysaccharides to aldonic acids ( 1), thereby stabilizing the polysaccharides towards endwise depolymerization (peeling) reactions. To explain the effectiveness of such small amounts of AQ , a cyclic mechanism has been Proposed in which AQ is continually reduced hy the polysaccharides and the reduced AQ species is oxidized back to AQ by the lignin (2,3). Although the oxidation of terminal aldehyde groups of polysaccharides by AQ under alkaline Pulping conditions is well documented , the effect of AQ on the random alkaline cleavage °Q£ glycosidic bonds is less well understood , * assisted random alkaline scission of - 9 lucosidic bonds occurs in solutions of amylose b th in the presence and absence of oxygen «°). For alkaline degradation of cellulose at - - - - EXPERIMENTAL General Pulp viscosities were measured as 0.5% cuene solutions by Tappi method T230 om 82. Carboxyl contents of the pulps were obtained by the methylene blue method (12). Cellulose tricarbanilates were prepared by the procedure of Schroeder and Haigh (13), and their molecular weight distributions (MWDs) were obtained by chromatography on a series of three Showdex columns , KF 806 , 805 and 804 , with tetrahydrofuran as the eluting solvent . - - Alkaline treatment of cotton cellulose Bleached cotton linters (4.0 g ) and 200 mL 1 M sodium hydroxide were placed in 500 mL steel vessels under nitrogen. Various additives were introduced , and the vessels were rotated , six at a time , in a hot air bath at 170°C. Af ter cooling and filtration , the treated pulps were kept at 60°C with a solution of 0.1 M sodium dithionite and 0.25M sodium hydroxide and then The procedure was repeated until the filtered. red colour of reduced AQ was no longer evident. As additives , AQ (208 mg , 1 mmol ) , 9 , 10 diacetoxy anthracene (DAA ) (294 mg , 1 mmol ) , 1 ,4 diacetoxybenzene ( 194 mg , 1 mmol ) , qlucose ( 1.8 g , 10 mmol ) and sodium dithionite - - - 89 (582 mg , 3.3 mmol) were used . Addi tion al exper iment s were perfo rmed in 180 mL vesse ls, with 5 g sampl es of cellu lose in 50 mL 1 M sodiu m hydro xide, and AQ ( 52 and 5.2 mg ) the addit ive. - Soda and soda AQ pulping of P. radiata P. radiata woodchips were digested at 170 C ° with 15.3 % active alkali as Na O and varying amounts of AQ. The liquor :wood ratio was 4:1 , time to 170 C, 1.5 h , and time at 170 C, 1.6 h. ^ ° ° RESULTS AND DISCUSSION Alkal ine degra datio n of cotto n cellu lose Comparative studies were carried out on the soda and soda AQ digestion of cotton cellulose , with AQ additions of 5 ,1 and 0.1% based on cellulose. The larger AQ charges were used in an attempt to simulate the soda AQ pulping of wood , during which AQ is continually regenerate d. In an oxygen atmosphere , soda 5% AQ digestion of cellulose gave higher yields and lower viscosities than did soda cooking , The same trend was in - - - 1 Th cellulo: oxidat ic aldonic ates of by size that the cooks tc molecule I (582 mg , 3.3 mmol) were used. The carbox yl conten ts of all the AQ treat ecj cellul oses were higher than the contro ls, due t0 oxidati on of cellul ose end groups by AQ to - Additional experiments were performed in 180 mL vessels, with 5 g samples of cellulose in 50 mL 1 M sodium hydroxide , and AQ (52 and 5.2 mg) aldoni c acids ( 1 ). The MWDs of the tricar banij ^ ates of the treated celluloses were determined by size exclusion chromatography , and showed that the loss in DP of the cellulose in the AQ cooks took place across the whole range of molecular weight (Figure 2 ). the additive. I Soda and soda- AQ pulping of P. radiat a P. radiata woodchips were digested at 170 C with 15.3 % active alkali as Na 20 and varying amounts of AQ. The liquor:wood ratio was 4:1 , time to 170 C, 1.5 h , and time at 170°C , 1.6 h. ° ° I RESULTS AND DISCUSSION Alkaline degradation of cotton cellulose Comparative studies were carried out on the soda and soda AQ digestion of cotton cellulose , with AQ additions of 5 ,1 and 0.1% based on cellulose. The larger AQ charges were used in - I an attempt to simulate the soda AQ pulping - . of wood , during which AQ is continually regenerated . In an oxygen atmosphere , soda 5 % AQ digestion of cellulose gave higher yields and lower viscosities than did soda cooking. The |same trend was noted in a nitrogen atmosphere , although the effect was smaller (Figure 1 ) , and for soda 1% AQ and soda 0.1% AQ cooks of cell ulose , the yield increase and viscosity decrease was still lower. Addition of 5% AQ to kraft cooks of cellulose gave less viscosity drop than I soda cooks. These observations on cotton lulose corroborate those of Carlson and ^ Samuelson (5), and contrast with those in which viscosity increases were noted (6,7). /*w / • \\ - - - c _ o 0.7 — i: i i: : // / / 10 20 \\ w w ww w Toluene \ \ 30 40 Elution volume ( m L ) l >N x o Figure 2. Size exclusion chromatograms of tricarbanilates of cotton cellulose ) and cellulose treated for 2 h with 1M NaOH without AQ ( •) and with 5 % AQ ( ) —O PE eE o 3 • / - cO ^ o u I .i . ow o 100 TD * 90 - Addition of 5 % AQ to soda cooks of cell ulose containing the reducing agent glucose 85 gave little yield enhancement and only snail viscosity reductions compared to the soda cooks. When glucose was replaced by sodium dithionite , no yield enhancement was observed with the AQ cooks , although a small viscosity drop again ensued. However , addition of either DAA or 1 ,4 diacetoxybenzene (sources of anthrahydro quinone or hydroquinone , respectively ) to soda 30 10 o I f 20 - >> o o - 10 */» > 0 I 0 1.0 2.0 Time of 170 *C ( h ) :e 1. Treatment of cotton cellul ) 10 ose at 170 C ° with 1 M NaOH , without AQ ( X ) and with 5 % AQ addition (0). - - dithionite cooks of cellulose gave no yield increases and , except for the early stages of the DAA cook (Figure 3) , no viscosity reductions. The MWDs of the DA.A treated celluloses were identical with the soda controls. - —_ % AQ . c o c O 0.5 S2 v. % scr. % pulp lignin yield in pulp 51.3 15.4 50.7 9.4 7.4 5.3 4.5 3.2 ZSTI Nm/g % a ZSTI - vise. Nm /g cell. mPa.s (a) (a ) (a) 81.5 81.4 80.9 82.2 81.4 80.9 171 159 159 160 154 142 eo e. 0.3 JD 100 0 0.05 0.1 0.2 0.5 1.0 90 a) chlorite delignified pulps 20 Table 1 Effect of AQ on the soda pulping of P. o E u o 49.0 49.2 49.3 50.0 150 165 161 155 151 148 22.1 20.4 20.3 16.4 18.9 18.5 radiata CL E » 10 • •* t/i decreased with increasing AQ charge , The ZSTI values may be dependent on the chemical o o w> > 0 composition of the fibre , and thus attempts at correlation of fibre strength with cell I 0 1.0 2.0 - T i m e a t 170 °C ( h ) Figure 3. Treatment of cotton cellulose at 170 C ° with 1 M NaOH and 0.017 M Na S^O. 2 2 4 without DAA (X) and with 7.3% DAA addition (O) - due to oxidation. This is in accordance with the proposal of Gierer et al. (14) that AQ _ - - pretreatment of pine wood oxidizes the poly saccharides, rendering them more labile toward s degradation during kraft pulping , However , although the results with cotton cellulose g random cleavage of the chains , the involvement - hydroquinone and trace amounts of oxygen remaining in the early stages of the cook , as has been previously suggested (5) , cannot be ruled out. - The effect of AQ on the soda pulping of P. radiata wood was investigated by carrying out a series of cooks using the same time /temper - - - addition of varying amounts (0 1 % ) of AQ (Table 1 ). REFERENCES The pulps resulting from cooks with increas AQ charges had lower lignin and higher carbohydrate contents. With the exception of the soda cook with no AQ addition , the zero - span tensile index (ZSTI) values of the pulps - - Soda AQ cooking of P. radiata wood ing - - suggest that AQ itself is the oxidant causin ature program and alkali charge but with - - Thus it appears that both the yield enhancement and decrease in viscosity observed when AQ is added to soda cooks of cellulose are of peroxide which may be formed from anthra ulose degradation from these results is difficult. After chlorite delignification , the pulps had similar a cellulose contents (Table 1 , although with increasing AQ charge the lignin contents were somewhat lower , and the carbo hydrate contents , particularly the glucomannan ( 15 ) , were higher. The pulps thus had similar contents of fibrous material. Both the cuene viscosities and ZSTI values for the delignified pulps decreased with increasing AQ charge. The lower viscosity of the soda 1.0% AQ pulp compared to the soda pulp was indicative of a DP decrease of ca.9% ( 16 ). Basta and Samuelson (10) have noted similar small viscosity decreases in soda AQ compared to soda pulps , while Kubes et al. found for black spruce soda AQ pulps , no change in viscosities in the range 0.1 0.5 % AQ addition. The decrease in ZSTI with increasing AQ charge shows that the presence of AQ in the digester leads to fibre weakening , These data indicate that AQ does promote random cleavage of glucosidic bonds in cellulose. The poss ibility of modification of cellulose by AQ which leads to fibre weakening without chain cleavage , as has been proposed by Eachus (9) for soda AQ cooking of holocellulose fibres , must also be considered. 1. L. Lowendahl and 0. Samuelson , Tappi , 61 ( 2 ) , 19 ( 1978) 2. B.I. Fleming , G.J. Kubes , J.M. MacLeod and H r. Bolker , Tappi , 61 (6), 43 (1978) 3 W.H. Algar , A. Farrington , B. Jessup , P F. Nelson and N. Vanderhoek , Appita , 3 3 (1 ), 33 ( 1979 ) . . _ . 91 4. F.L.A. Arbin , L.R. Schroeder , N.S. Thompson and E.W. Malcolm , Tappi , 3(4 ) , 152 (1980); Cellul. Chem. Technol., 15(5), 523 (1981) 5. U. Carlson and 0. Samuelson , Svensk Pappers tidn • 9 82(2), 48 (1979) £ - . 6. K.H Paik and H. Augustin , J. Tappik , 15(2), 8 (1983); Chem. Abstr. , 100 , 123009 (1984) 7. A. Satoh , J. Nakano , A. Ishizu , Y. Nomura and M. Nakamura , Kami Pa Gikyoshi , 33(6), 410 (1979) 8. K.H. Paik , Nonglim nonjip , 2 3 , 15 (1983); Chem. Abstr • 9 101, 232111 (1984) 9. S.W. Eachus, Tappi J • 9 66(2), 85 (1983) 10. J. Basta and 0. Samuelson , Svensk Papperstidn 81(9), 285 (1978); 82( 1), 9 (1979) 11. G.J. Kubes, J .M. MacLeod , B.I. Fleming and H.I. Bolker , J. Wood Chem. Technol., 1(1), 1 (1981) 12. W.K. Wilson and J. Mandel , Tappi , 44(2), 131 (1961) 13. L.R. Schroeder and F.C. Haig , Tappi , 62(10), 103 (1979) 14. J. Gierer , M. Kjellman and I. Noren , Holzforschung , 37(1), 17 (1983) 15. J.M. MacLeod , H. Iwase and H.I. Bolker , Tappi J., 67(5), 123 (1984) 16. H. Sihtola , B. Kyrklund , L. Laamanen and I. Palenius, Paperi ja Puu , 45 , 225 (1963) _ 4 f • f 2 - - A NOVEL CLASS OF MICRO ACETYL XYLAN ESTERASES BIAL ENZYMES INVOLVED IN THE DEGRADATION OF HEMICELLULOSE tics of an enzyme cataly:eu reaction , The rate of acid liberation was proportional to the amount of enzyme and the time of incubation , The pH optimum was about pH 6.5. Reaction did not occur with heat denatured enzyme preparations. The fungal esterases differed from purified orange peel acetylesterase , porcine liver este rase and pectinesterase m specific activities towards acetyl xylan and 4 -nitrophenyl acetate. T u fungal preparations were relatively more active on acetyl xylan as shown by the ratio of esterase activities measured (Table 1). The specific activities of fungal preparations on acetyl xylan were invariably greater , even though these preparations were crude protein mixtures. Acetyl xylan esterase activity was not associated with a pectinesterase. - P. BIELY * , C.R. MACKENZIE , J. PULS'* AND H. SCHNEIDER DIVISION OF BIOLOGICAL SCIENCES , NATIONAL RESEARCH COUNCIL OF CANADA , OTTAWA , CANADA KlA 0R6 ; * INSTITUTE OF CHEMISTRY , SLOVAK ACADEMY OF SCIENCES , BRATISLAVA , CZECHOSLOVAKIA ; **INSTITUTE OF WOOD CHEMISTRY , BFH , HAMBURG , FRG. ABSTRACT Fungal cellulolytic systems contain esterases that deacetylate naturally occurring plant acetyl xylans. The esterases act synergistically with xylanases in the degradation of the acetylated polymers. INTRODUCTION The xylan of several wood species is acety lated . Consequently , microorganisms in at least some natural habitats face the task of degrading an acetylated , rather than a deacetylated polymer. To date , studies of xylan degradation by micro bial enzymes have used as a substrate only the deacetylated material obtained on alkaline extrac tion of delignified holocellulose , hence a polymer that does not occur naturally. The sequence of enzymic reactions involved in the degradation of the acetylated polymer is unknown. One possibility is that enzymic deacety lation is a prerequisite for subsequent hydrolysis by xylanases and xylosidases. While the existence of enzymes that deacetylate xylan might have been anticipated , they do not seem to be described previously. The present study points to a wide occurrence of esterases of this type and delineates aspect of their role in the degradation of acetyl xylan. - Table 1 - - - - RESULTS The substrates used were: a non dialysable fraction of water soluble hemicellulose produced by the steaming of birch , and a water soluble polysaccharide extracted from beechwood holo cellulose by dimethyl sulfoxide , Both polymers were characterized by 1 3 C NMR spectroscopy as highly acetylated xylans. Acetic acid content exceeded 10% in both samples. Acetyl xylan esterase activity was found in commercial preparations of cellulase enzymes from Trichoderma reesei ( Novo), T. viride (Onozuka ), *rid Aspergillus niger (Sigma). The activity was found also in media of cultures of Schizophy 1 lum commune grown on cellulose and Aureobasidium llul lulans grown on xylan. The liberation of acetic acid from acetyl xylan showed ch \ racteris - - - - - - - Enzyme preparation 4 Nitrophenyl Acetyl xylan acetate esterase esterase Ratio *U/mg prot. T. reesei cellulase T. vinde cellulase A. niger cellulase S. commune cellulase A. pullulans xylanase 0.061 G .027 0.135 0.363 1.75 0.043 0.08 0.041 0.072 0.39 4.5 Acetylesterase (orange) 1.47 Esterase (porcine 49.7 liver ) Pectinesterase (orange) 0.16 0.022 0.011 66.8 4518.2 0.004 40.0 1.4 0.34 3.3 5.0 *1 umol/min Separation of components of the cellulolytic systems of T. reesei and S. commune by HPLC on a - - TSK DEAE 3SW column resulted in fractions contain ing acetyl xylan esterases and xylanases that were not mutually contaminated. As with the crude fungal preparations , the xylanase free esterase fractions showed much higher reactivity towards acetyl xylan than the plant and animal esterases. Based on these observations , the T. reesei and S. commune esterases are considered to represent a novel class of carbohydrate esterases involved in the degradation of native hemicellulose. The availability of xylanases and acetyl xylan esterases that were not mutually contaminated enabled investigation of the ability of xylanases to hydrolyze acetyl xylan as well as to assess the role of the esterases in the overall degradation. Xylanases alone hydrolyzed acetylated xylan to a much lesser extent than in the presence of an acetyl xylan esterase. An example of the birch acetyl xylan degradation by S. commune enzymes is shown in Table 2. The table also shows that the - 93 same number of units ( 4 -nitrophen yl actetate used as substrate ) of orange peel acetylest erase had ly slight effect on the reaction , substant iat the view that the esterase of S. commune is relativel y specific for acetyl xylan. ing lated xylan. The presence of xylanase increase d the rate of acetic acid liberati on from acetyl xylan by a S. esterases. Table 3 summariz es the effect of commune xylanase on acetic acid liberati on from the birch acetyl xylan by an acetyl xylan esterase from T reesei. Table 2 . Reducing sugars released by Reaction xylanase time alone xylanase* acetyl xylan esterase Table 3 xylanase * orange umol xylose equivalen ts/ml min 10 0.27 30 0.78 60 120 180 240 1.12 1.30 1.36 1.39 0.59 1.00 1.30 1.53 1.62 * v*s onr"T' % . r . * (&v( ihw2 o! i - •>:. 'J£ : o.• r 7• * * * > * / * * * **. • + ; * v: • - „ v. * • m / m • — I i*: > A nnr » 4' Xylose A • V* iifij Xylotrio se . ki j1 0 5 10 S nJfL 19 & i J « WIOJ > o 5 10 15 ' Xylotetr aose 5 10 15 Figure 1. Thin - layer chromato graphy of the pro ducts of hydrolysi s of deacetyla ted .iirch x y l a n ( A ) and acetylate d birch xylan by a Sch 1 zophvllum commune xylanase in the presence ( B ) and in the absence (C ) of acetyl xylan esterase from the same organism. The numbers indicate tne time of incubati on in hours. S, standard s; arrows , acetylate d xylooligo saccharid es. - alone released small quantitie s of both acetylate d and non - acetylate d xylooligo sacchari des. When an acetyl xylan esterase was added , the majority of the products correspon ded to non acetylate d xylooligo saccharid es, such as those formed upon the action of xylanase on deacety r\ A / lanase 0.026 5.5 21 45 0.082 0.23 0.35 0.041 0.071 0.13 0.52 0.55 reaction medium. i ' ^ &A} rfiiw ?./ 1.5 3.5 0.05 - ' ^ !r.> 3iffoJT mX *.rUi T; f V - vt' AilK Xylobiose 1 present polysacch aride. A decrease in the polymeri zation degree of the substrate by xylanases also contri buted to the frequency of esterase-substrate interacti on by decreasin g the viscosity of the rr f r *:,t towi + 100, 0 Xylanase absent productiv e binding with xylanases. The positive effect of xylanases on the deesterif ication of acetyl xylan by esterases was due to a preferenc e of esterases to deacetyla te shorter fragments rather than the original high molecula r weight C B Xylanase DISCUSSIO N The synergist ic action of xylanases and esterases during the degradati on of acetyl xylan could be interpret ed as follows. Esterases, by liberatin g acetic acid , created new sites on the polysacch aride backbone suitable for subsequen t lysates by thin-layer chromato graphy ( Fig. 1 ). \ T • I Reaction time (h) 0.18 0.22 0.71 1.47 2.03 2.35 2.40 The kinetics of acetyl xylan degradati on by xylanase plus or minus esterase correlate d well with the results of the analysis of the hydro- A Concentr ation of released acetic acid ( % ) peel esterase - the range of S 1 2 Kcal / mole , b e i n g h i g h e r above the Tg of cellulose in w a t e r , e.g . 2 5 °C. The - r a t e s of crystallization v a r i e s for cel h loses LESS ORDERED REGIONS ( LOR ) OF CELLULOSE CHEMICAL APPROACHES NEW of different o r i g i n s bv over 4 o r d e r s of m j v - nitude , whereas the a c t i v a t i o n enc gy is the same. Menuchem L e w i n Israel Fiber I ns 111 u t e , POR 8001 , Jerusalem 91080 Israel The r a t e of crystallization with increases the o r i e n t a t i o n factor of the cellulose . Yields and r a t e s of c r y s t a l l i z a t i o n i n c r e a s e a t higher t e m p e r a t u r e s and orient , tions which c r e a t e more favorable conditions : «. r the for ABSTRACT nation of intermediate While the crystalline domains of cellulose have been extensively investigated by chemical - a decrease in w a t e r a b s o r p t i o n in th * - . - - A t w o s t e p procedure Is used for the deter mination of the a v e r a g e s i z e of a n LOR . F i r s t , a c t i v e carbonyl groups are produced by a con trolled mild oxidation of the cellulose. LOR a s distinct from the a b s o r p t i o n on the walls of dered r e g i o n s of the fibers , In the fol lowing , several new s y s t e m s d e a l i n g with the average size of a less ordered r e g i o n , with the dynamic n a t u r e of accessibility and with new a s p e c t s of w a t e r a b s o r p t i o n a r e discussed s t r u c t u r e s inside the polymer p h a -» i* . The increase in crystal 1 ini t v b r i n g s about as well a s physical methods , little attention has been p a i d to the n o n crystalline , less or - liquid crystalline - In the second s t e p , the oxidized cellulose is exhaus tively extracted with a mild bicarbonate solu tion under reflux , whereby the " peeling ” reac - - the c r y s t a l 1 it es . Linear relationships are obtained between accessibility and w a t e r absorption for any s e r i e s oc celluloses p r o - duced from an initial basic cellulose by crystallization with b r o m i n e t o i n c r e a s i n g l e v e l s. E x t r a p o l a t i o n t o z e r o accessibility yields a value for w a t e r absorbed o n tht walls of the crystallites w h i c h is characteris Ic for the s e r i e s and defines the size of : e crystalline regions. tion i n i t i a t e d by the active carbonyls is pro ceeding along the chains in the LOR , producing 1 sosacchar in ic acid and the characteristic yellow chromophore. It is stopped a t the e d g e of the crystalline r e g i o n s. From the knowledge of the number of a c t i v e carbonyls and the a m o u n t of cellulose dissolved , the a v e r a g e length of a chain in the LOR can be calculated by means of a statistical theory of alkaline depolymeriza - tion. - In another s y s t e m , the a c c u r a t e determina tion of accessibility is achieved by d e t e r m i n i n g the reversible sorption of bromine from bromine w a t e r on cellulose , which was shown t o proceed - according t o the L a n g m u i r isotherm , This meth od correlates linearly with IR and X ray deter minations of c r y s t a l l i n i t y a s shown for lb celluloses ranging from U t o 70 X accessibility. - - The accessibility values obtained w e r e shown , a t bromine concentrations h i g h e r than 0 , 0 2 m / 1 t o change with the contact time of the cellulose with the bromine solution , with the concentration of the bromine s o l u t i o n and with the n a t u r e of the fiber Dec rystall Izn . - tion and crystallization rares studied were found t o be of the first order , both t o t h e LOR concentration in the fiber and t o the bromine concentration The activation e n e r g i e s were in . 95 VAS : LOSS OF WOOD AND ITS COMPONENTS DURING TRANSMISSION ELECTRON MICROSCOPY M . MARY, J F. REVOL AND D.A.I. GORING .- M MQ PULP AND PAPER RESEARCH INSTITUTE OF CANADA 570 ST JOHN 'S BLVD. - 1.0 09 POINTE CLAIRE , QUEBEC H9R 3J9 o.a When a sample of biological material is under 1 - observation in a transmission electron micro scope (TEM), it is severely damag 'd by electron irradiation [1]. The most important result of Figure 1. 2 3 . D (c.prr ? 10 10) 4 5 6 7 0 " Mass loss of bl » ck spruce od due to an irradiation with 100 ke ^electrons at room temperature. The thickness of the sample is < 500 nm. this damage is a rapid loss of mass which can range from 10 to 90% depending on the chemical - composition of the specimen [2 4]. - Wood is a composite of three biological ma cromolecules and the extent of its damage during electron microscopy is not known. The goal of the present work is to quantify the damage by measuring the decrease in weight of the whole wood as well as of its three major constituents when they are in a TEM for imaging or for micro beam analysis. As electrons pass through a specimen, charac - 1.0 0.8 I G M 0.6 M0 - 0 . 4 - 0.2 teristic X rays are emitted corresponding to the different elements. In addition , a continuum of X radiation (also called Bremsstrah lung or "white ” radiation) is generated. The decrease in intensity of this X ray continuum while the electronic irradiation proceeds corresponds to the change in the specimen mass per unit area [5]. Thus the mass loss of a specimen may be measured by use of an X ray spectrometer on a transmission electron microscope. Figure 1 shows the mass loss of the whole wood plotted against the dose for doses smaller than 10~ 9 c/ m 2. The trend is linear and extra polation to the original mass of the sample is precise. The vertical dashed line represents the dose at which the crystallinity of the cel lulose as detected by electron diffraction dis appears , and corresponds to a total dose of about 2 • 10"!1 c/ m 2. The mass loss at this level of irradiation is negligible. In Figure 2 the mass loss is plotted against the dose for much higher levels of irradiation. The decrease of the mass is quite rapid until it reaches an approximately constant value for doses higher than 5 • 10~ 8 c/ m 2. The percen tage of mass remaining in the whole wood at this level of irradiation is only 42 %. When the electron beam current ( flux of the electrons) was varied , essentially no change was found in the curve of mass loss versus dose. 0 % WOOD 2 4 - ^ - ^ ^ - 8 10 o 12 D ( c.pm ? 10 8 ) - - 6 - O O' Figure 2. Same as Fiqure 1 but for higher elec tron irradiation doses. - Furthermore , no change was noted when the thick ness of the sample was varied from 150 nm to 500 nm. Thus , the loss of mass in a TEM operated at 100 kV is independent of the dose rate and of - the specimen thickness up to 500 nm. Figure 3 shows a series of curves represent ing the mass loss of wood , cellulose from Valo - - nia ventricosa , periodate lignin and xylan. The curves are similar in shape, decreasing to a constant value of mass loss after a dose of about 5 • 10“ b c/ m 2. However, this constant value is different for each type of sample , The proportion of mass remaining after long irradia tion is 32% for cellulose , 45 % for xylan and 70% for periodate lignin , By assuming that these three samples are representative of the cellu lose, hemicellulose and lignin in black spruce ^ - - wood in the proportions 50:25:25, respectively, it is possible to calculate the mass loss of the whole wood. The value thus obtained is 44.7% which is in good agreement with our result ob tained by direct measurement , i.e. , 42%. - 97 - It seems likely , therefore, that , in the high resolution microbeam analysis of woody material , 1.0 the effects of mass loss will be elucidated only when the sensitivity of the method has been 0.8 improved considerably , In the meantime caution should be exercised in the interpretation of the /PERIODATE LIGNIN M Mo 0.6 results obtained. * XYLAN 0.4 \ WOOD 1 . ^ CELLULOSE 0.2 2. 0 0 2 4 6 8 10 BAHR , G.R • JOHNSON , F.G. and ZEITLER , E. elementary composition of organic ob jects after electron irradiation , Lab In vest 14: 115 (1965) $ -- The 12 D ( c.pm ? 10 B ) Finure 3. COSSLETT , V.E. Radiation damage in the high resolution electron microscopy of biological materials: a review. J Microsc 113: 113 (1978) Mass loss of black spruce wood and its components due to an irradiation with 100 keV electrons at room tempe rature. The thickness of the samples is < 500 nm. - 3. REIMER , L. Irradiation change in organic or objects. i4: 344 Lab Invest inorqanic (1965) - 4. EGERTOtJ , R.F. Measurement of radiation da mage by electron energy loss spectroscopy. J Microsc 118: 309 ( 1980) 5. HALL, T.A. and GUPTA , B.L. Beam induced loss of orqanic mass under electron micro scope conditions. J Microsc 100: 177 (1974) lamella and the secondary wall of the cell , and a more accurate interpretation of the images becomes possible if mass loss is taken into account. Examples are given. 6. SAKA , S • » WHITING , P • 0 FUKAZAWA , K. and GOR ING , D.A .I. Comparative studies on lignin distribution by UV microscopy and bromina tion combined with EDXA. Wood Sci Technol 16: 269 (1982) Several papers have recently been published rom this laboratory [6 9] and elsewhere [10 15] 7 . SAKA , S. and GORING , D.A.I. The distribu tion of inorganic constituents in black spruce wood as determined by TEM EDXA. Mo kuzai Gakkaishi 29: 648 (1983) The difference in mass loss between lignin and the carbohydrates will lead to differences in contrast between the TEM images of the middle - - - - - - cases, the sensitivity of the signal to the time of irradiation was measured and no change in intensity was found [7 12]. However , in gene ral irradiation greater than 10~ 7 c' m 2 is required for quantitative microbeam analysis. For such high doses, it is likely that mass los3 will occur even before the first measurement can be made. All observations will correspond , - . 8. 9. - ^ resolution is several orders of magnitude too coarse to allow measurements in morphological regions in wood such as the middle lamella or Nr > doubt the loss in weight te torus could be educed by keeping the sample at low tempera tures in a cooling stage [5, 16] However, even . . - very low temperatures, such as that of liquid h* ii urn, some rtamaqe is still present ri 7, lfl]. KUANG , S.-J • $ SAKA , S. and GORING , D.A.I. The distribution of chlorine in chlorinated spruce and birch wood as determined by TEM EDXA. J App 1 Polyn Sci 37: 483 ( 1983 ) . - KUANG , S. J., SAKA , S. and GORING , D.A.I The distribution of chlorine in chlorinated kraft pulp fibers from spruce wood as deter mined by TEM EDXA J Wood Chem Technol 4: 163 ( 1984) - ^ . - - therefore , to the level off intensities shown in Figures 2 and 3 Clearly such effects should be taken into account in the interpretation of quantitative results. Unfortunately with the sensitivity presently available it is difficult to make measurement of initial mass loss ( as shown in Figure 1 ) with a spot size less than 40 m in diameter, This - - - in which the microscopic distribution of certain elements in wood has been measured by electron microscopy coupled with an energy dispersive X ray analyser (SEM EDXA or TEM EDXA ). In some - - . 10. SAKA , S., THOMAS, R.J. and GRATZL, J .S. Lignin distribution by energy dispersive X ray analysis In INGLETT , G.E., FALKEHAG , ( eds.): Dietary fibers: chemistry and I F nutrition. Proceedings of American Chemical Society , Miami, Florida, September , 1978 .. 11. SAKA , - . . .. S , THOMAS , R.J. and GRATZL, J S Lignin distribution: determination by ener gy dispersive analvsis of X rays. Tanpi 61( 1 )i 73 (1978) - - - 12. SAKA , S. and THOMAS , R .J . Evaluation of the quantitative assay of ljnnin distribution by SEM EDXA technique. Wo d Sci Technol 16: l ( 1982) - 13. SAKA , S., THOMAS , R.J., GRATZL, J .S. and AR SON , J .S . Topochemstry of de 1 igni f ICAT ion in Douglas fir wood with soda , soda anthra quinone and kraft pulping as determined by SEM EDXA Wood Sci Technol 16: 139 ( 1982) - - - . . SAKA , S . and THOMAS , R.J. 14 - A study of ligni fication in loblolly pine tracheids by the SEM EDXA technique Wood Sci Technol 16: 167 ( 1982) - . 15. GARDNER , D.J ., GENCO, J.M., JAGELS, R. and SIMARD, G.L. SEM EDAX technique for measur ing liqnin distribution in pulp fibers. Tappi 65(9); 133 (1982) - - Organic mass loss at 100 K 16. EGERTON , R.F. and 300 K. J Microsc 126: 95 (1982) E., LEFRANC, G., HEIDE, H.G. and DIETRICH , J. Electron microscopical results on cryoprotection of organic materials ob Ultramicrosc 10: tained with cold stages. 105 (1982) 17. KNAPEK , - 18. KNAPEK, E. Properties of organic specimens and their supports at 4 K under irradiation in an ele :tron microscope. Ultramicrosc 10: 71 (1982) t e c h n i c a l l y v a l u a b l e u n l e s s t h e i r dellgnlfylng c a p a c i t y was . n:reased . A f t e r m u c h difficulty , w e succeeded BIOLOGICAL PULPING "c o n s t r u c t i n g " - Cel “ s t r a i n s w i t h an increased phenol o x i d a s e a n d x y l a n a s e KARL E' IK ERIKSSON AND SUSANNA C. JOHNSRUD p r o d u c t i o n (6 ). However , a l t h o u g h the n e w m u t a n t s were c o n s i d e r a b l y b e t t e r than t h e i r SWEDISH FOREST PRODUCTS RESEARCH LABORATORY BOX 5604 S 114 0 6 STOCKHOLM , SWEDEN prececessors , t h e y 6 t i l l had a lower c a p a c i t y for l i g n i n d e g r a d a t i o n i n wood than t o the w i I d t y p e (6). Another m e t h o d for o b t a i n i n g a more s p e c i f i c - - d e 1 i g n i f i c a t i o n o f w o o d i s t o i m p r e g n a t e wood c h i p s w i t h sugar b e f o r e i n o c u l a t i o n with the ABSTRACT w i l d t y p e fungus. The p r e s e n c e o f glucose w i l l At t h e Swedish Forest P r o d u c t s Research L a b o r a t o r y (STFI) o n e a p p r o a c h t o save e n e r g y in the p r o d u c t i o n o f both m e c h a n i c s r e p e s s the p r o d u c t i o n of p o l y s a c c h a r i d e - and l i g n i n i s o b t a i n e d ( 1 0). T h i s i s illustrated in - c h e m i c a l pulp has been t o u s e c e 1 1 u 1 ase 1 e s s - ” ( Cel ) m u t a n t s of w h i t e r o t f u n g i t o degrade , or s t r u c t u r a l l y m o d i f y , p a r t of the l i g n i n In w o o d c h i p s ( 1 6). W h i t e r o t f u n g i a r ? able t o - - d e g r a d e both l i g n i n a n d the o t h e r wood c o m p o n e n t s. To degrade l i g n i n , t h e y n e e d poly - a t t a c k i n g e n z y m e s and a s p e c i f i c a t t a c k o n t h e F i g . 1 w h e r e it i s d e m o n s t r a t e d by t r a n s c s s l o n - - s a c c h a r i d e s a n d / o r low molecular w e i g h t s u g a r s , partly t o p r o v i d e t h e e n e r g y for g r o w t h a n d m e t a b o l i s m a n d partly t o p r o d u c e h y d r o g e n p e r o x i d e which a p p e a r s t o b e i m p o r t a n t for - l i g n i n d e g r a d a t i o n (8 9). A totally s p e c i f i c a t t a c k o n the l i g n i n c o m p o n e n t probably d o e s n o t occur . - If t h e c a p a c i t y of w h i t e r o t f u n g i t o d e g r a d e lignin could be m a d e m o r e s p e c i f i c w e 9 t h o u g h t that it w o u l d be p o s s i b l e t o s a v e O.o(im energy i n mechanical p u l p i n g a n d probably a l s o i n c h e m i c a l pulp p r o d u c t i o n. In a d d i t i o n , it would probably a l s o be p o s s i b l e t o produce a more e a s i l y d i g e s t i b l e a n d a l s o a more e n e r g y - r i c h fodder for r u m i n a n t s from a g r i c u l t u r a l - w a s t e s u c h a s s t r a w a n d b a g a s s e if the l i g n i n could be specifically deleted . We h a v e tried t o r e a c h these g o a l s a t STFI - by isolation and u t i l i z a t i o n of c e 11 ulase 1 e s s - - (Cel ”) m u t a n t s of w h i t e r o t f u n g i . The o r i g i n a l technique for p r o d u c i n g t h e s e m u t a n t s w a s by UV 1 rradiation of asexual s p o r e s ( 1 2). P r a c t i c a l trials t o dellgnify wood c h i p s w i t h t h e m u t a n t s o b t a i n e d c e r t a i n l y led t o energy s a v i n g in mechanical p u l p i n g but the process also led t o a d i s c o l o r a t i o n of t h e pulp ( 5). T h e r a t e of de 1 i g n 1 f i c a t i o n a c h i e v e d w i t h these first m u t a n t s was a l s o t o o low. From o u r e x p e r i m e n t s we understood that “ C e 1 m u L n n t a produced o n l y by r a n d o m m u t a t i o n of con 1 d 1 ospores were u n l i k e l y t o become - - - F i g u r e 1. T r a n s m i s s i o n electron m i c r o g r a p h of g l u c o s e i m p r e g n a t e d s p r u c e wood i n c u b a t e d w i t h t h e wild t y p e o f the w h i t e r o t f u n g u s Sporotrlchura pulverulent urn Due t o t h e g l u c o s e i m p r e g n a t i o n , the p o l y s a c c h a r i d e attacklng e n z y m e s are repressed a n d a s p e c i f i c attack o n the l i g n i n i s obtained . In the p i c t u r e , the cellu lose f i b r i l s h a v e been exposed (a r r o w s) by the s o l u b i l i z a t i o n of the lignin matrix which is still v i s i b l e i n s o m e areas (double arrow ), from ( 1 0) - - - - . - - - . electron m i c r o s c o p y that c e l l u l o s l c fibrllls become exposed (arrows) by the solubilization o f the l i g n i n m a t r i x . U n f o r t u n a t e l y , even though very s p e c i f i c d e 1 i g n 1 f 1 c a t i o n can be obtained in t h i s way i t i s probably n o t econo m i c a l l y or technically feasible t o Impregnate . - wood w i t h s u g a r s. 101 I At this stage, we decided that a return to The Inability of the mutants to degrade basics was necessary for a better understanding of the biology and physiology of the fungi and c e l l u l o s e w a s i n v e s t i g a t e d i n s e v e r a l w a y6 , o n e o f w h i c h w a s b y s t u d i e s o f B C02 d e v e 1 o p ment from [U ] 1 a b e 1 1 e d c e l l u l o s e. T h e ability to degrade lignin was studied partly by m e a s u r e m e n t o f t h e a m o u n t o f BC O2 d e v e l ring labelled synthetic lignin oped from f t h e m e c h a n i s m s b y w h i c h t h e y d e g r a d e l i g n i n. It was discovered during this work that the fungus Sporotrlchum pulverulentum was a Basidiomycete, Phanerochaet e chrysospor 1 um , w i t h a f u l l s e x u a l c y c l e (J o h n s r u d , S.C . , i n p r e p a r a t i o n ). T h i s m a d e p o s s i b l e t h e u s e o f I classical genetics in order to obtain the s t r a i n s w e w e r e s e e k i n g , l .e . c e l l u l a s e l e s s - - v a r i a n t s w i t h a h i g h l i g n i n d e g r a d i n g p o w e r. T o accomplish this, horaokaryotic Cel - ’ strains , B C- - - - - - Be and partly by estimation of the lignin and weight losses caused by the new mutants in - w o o d. T h e l i g n i n d e g r a d i n g a n d c e l l u l o s e - -d e g r a d i n g c a p a c i t i e s o f d i f f e r e n t s t r a i n s o f -m u t a n t s c a n P. c h r y s o s p o r 1 u m a n d t h e i r C e l ’ b e s e e n i n F i g . 3. I t i s o b v i o u s t h a t t h e selected for their superior ability to degrade - lignin, were crossed with wild type strains of - I . 40 e q u a l l y h i g h l i g n i n d e g r a d i n g c a p a c i t y. H o w uC - r n g - DHP UC [U] Cellulose these crossings of the different strains were c a r r i e d o u t i s d e s c r i b e d i n F i g . 2. T h e n e w mutants are equal to , or even better than, the s^ - o Sporotrichum pulverulentum I I o o Single comdiospore culture C Phanerochaete chrysosporium 1 * o o K- 3 20 1 T3 / T O t * Selection F 1 1 3 i E3 I u 31 UV s 30 o I 1 . u < 1 3113 to t 1 Crossing 1 1 1 1 13132 K-3 1 Release of - 2 -better l a s ethe of Scheme for the selection , mutation and intercrossing of horaokaryotic strains of Phanerochaete chryso s n o r l i n n K 3. ( P • c h r y s o s p o r l u m K 3 is a single conidlospore Culture of S p o r o t r 1 c hum pu l v e r u l e n t u m ). C e l l u l a s e p o s i r i v e s t r a i n s: K 3, 3 1 , -- - - 1 3 2 , 1 3 1 1 2. C e l l u l a s e d e f i c i e n t strains: 3113 , 3 1 32 8 5 , l 3 1 3 2 1 1 8 , 8 5 1 1 8 f r o m ( 11 ). 102 ‘ strains degrade B e- ^ - - 104 - - - . Ignln as well as or - even ce 1 lu i from - strains Cel - BCQ T ^ ^ ^ -. 3 1 , 1 3 2 , 1 3 1 3 2. C e l l u l a s e d e f i c i e n t : 3 1 1 3 , 1 3 1 3 2 - 8 5. 1 3 1 3 2 - 1 1 8 , 8 5 1 1 8 f r o m ( 1 1 ). Selection F 3 I . - - 85118 I 1 3113 13132 13132 13132 85118 85 118 r i n g l a b e l l e d D H P (3 . 0 x d p m) * C [ ll] ce 1 l u l o s e ( 3 0 x and from 1 0* d p m ) Phanerochae t e chryso sporium K 3 and Isolates of the F , F and F generations C e l l u l a s e p o s i t i v e s t r a i n s: K 3 Crossing I 1 132 Strom . Figure 2 31 Selection Fp Figure 3 I * toodard deviation mean volue wlldtype in their lignin degrading capacity ( 11 ). • * than the wild type and the p o s 1 1 1 v e s t r a i n s. T h i s i s a l s o t r u e degradation of lignin In wood. The w e i g h t a n d l i g n i n l o s s e s i n b i r c h wood c a u s e d by the wild type K 3 and four new C e l - - strains are shown In table l - . After two weeks , photic po. . mers such us polyvinyl acetate ( PVAc ) , cellulose acetate, polyethyl acrylate or polyinethyl methacrylate ( 1 . Th * » Dolymur mixtu. es exhibit a one phase morpho logy , have a lower cintical solution temperature ( LCST) of ca . 140°C , are thermoplastic , and swell in water up to 80 times their dry weight . CHEMICALLY MODIFIED LIGNIN FOR THE USE IN CONTROLLED - RELEASE DEVICES A.H.A. TINNEMANS * AND H.F. MARTENS TNO INSTITUTE OF APPLIED CHEMISTRY P.O. Box 5009 3502 JA UTRECHT, THE NETHERLANDS These blends , called Aqualloy polymers , have been usee as release matrix because of their potential to control water sorption and sorption rate by simply choosi ng the right mixing ratio G.J. VAN VELDHUIZEN AND P.J. GREIDANUS . TNO PLASTICS AND RUBBER RESEARCH INSTITUTE P.O. Box 71 , 260C AB DELFT, THE NETHERLANDS We have invjstigated the feasibility of preparing water -swellable polymers comparable with the Aqualloy poly - mers in which type of polymers the polyvinyl esters ABSTRACT Kraft lignin and organosolv lignin have been modifi ed used in the formation of homogeneous blends by solvent are relevant for controlled -release applications, alloying of appropriate resins. ALLOY CHARACTERISTICS - a low glass rubber transition temperature. Severa l examples bility of ternary and quaternary mixtures. Most polymer mixtures are not completely rnisci Lle and - do show phase separation. However , due to polyme r specif - - -50 structural homogeneity. 62AG — In order to evaluate potential matrices for contro lled- 6 2 -release systems we have determined some water -swelling characteristics such as swell ratio, swell rate, and sorp tion behaviour depending on pH and ionic streng th The thermoplastic processability and flexibility of the INTRODUCTION Polymer blends with high water absorption cognized as interesting materials when - have been re designing controlled- -release devices for bioactive materials. Examples are polymer- polymer complexes consisting of opposi tely charged poly electrolytes which absorb large amounts of water , forming elastic hydrogels( 1 4). However , these polyelectrolyte com plexes are Insoluble in organic solven ts and do not exhibit thermoplastic behaviour. As they cannot be processed - by casting , moulding or extrusion , the applicability of hydro jel polymers in controlled releas e systems is limited . )ther disadvantages are the limited number of parameters to idjust optimal release profile ( e.g equilibrium swelling , - . Jwell kinetics, and pH dependence of swelling ) , and the complex and co9 tly production techni ques. Likewise , a hydro ? el polymer matrix is too expensive for large -scale applic- is the free energy of mixing and m resembles the volume fraction of one of the blend 'eloped overcoming most of the disadvantages of lli relation is m ^- parabolic and shows a minimum . Then , the above miscib ility criterium is fulfilled for all blend ratios , because the entropy of mixing is negligible for high molecu lar weight blend constituents. Specific interactions may arise from several mechanisms but dipole-dipole intera ctions and hydrogen bonding are the most relevant interactions in mixtures with exothermic heat of mixing Generally , besides these exothermic intera . ctions also dispersive or Van der Waals forces between the remaining parts of the polymer constituents, not involved in specific interactions play an important role in the homogeneous, one-phase blend. These forces contribute endothermically to the enthalpy. However , dispersive forces are mixing indispensable at the formation of non-disinteqrating elasti c hydrogels They analogize with the covalent bonds in cross linked polymers. We studied the miscibility and sorpti on behaviour of a series of binary, ternary and quaternary blends comprising modified lignin as one of the constituents For instance , optically clear films , cast from a 20 * w / v solution of a 1 : 1 blend of polystyrene maleic anhydride copoly . - . mer ( PS - MAI . 2.105 and an acylated lignin , swell about 60 times their w has been de M the present - own weight In distilled water , cf. Figure . l - . AH be- comes negative ( exothermic ) , while the AH / - Recently , a new and unique polymer concept important role in blend formation , the enthalpy of mixing . most promising ternary mixtures have been tested by measuring melt - index , mechanical properties and glass- rubber transition temperature. > 0, where AG constituents. If specific interactions play an - y available hydrogel polymers. The ic le, forming under certain conditions blends with a one - phase morpho logy. One - phase mixtures are only thermodynamically stable when times their own weight, provides a good indica tion of their tydrogcls, which consL*. - interactions the mixtures may become miscib The swellability of these blends in water , being 30 ations in agriculture will be discussed. The brittleness of these alloys has been reduced by adding another compatible polymer to the mixture which has i - ives of kraft pine lignin and organosolv birch lignin. The characteristics of these hydrophylic polymer alloys , which by acylation and alkylation in such a way that they can be will be presented showing the optimization of the compat . etc are replaced in part by acylated and /or alkyla ted derivat concept Is based on or ucroogeneous mixtures of water - 105 4. T 1 me (w e e k s) Strain Weight 1 o s8, (2) Lignin l o s s'1 ' ( > . * SAMUEL SSON , L. MJOBER C , P.J ., HARTLE R , N., VALLAN DER , L. ind ERIKSS ON , K . E . I n f l u e n c e of fungal t r e a t m e n t o n t h e s t r e n g t h versus e n e r g y r e l a t i o n s h i p i n raechan ica p u l p i n g. S v e n s k Papper stldn 8 3 : 221 2 2 5 ( 1 9 8 0) f - - - 0 2 3 4 18.5 19.9 .* .4 17.7 17.2 19.9 3113 2 3 6.0 !.9 4 14.0 19.0 18.5 29.5 2 3 4 11.3 18 2 19 6 - 16.0 28.5 25.6 13132 1 1 8 2 3 4 6.9 11.7 10.5 13.3 13.9 18.4 85118 2 3 4 10.6 21.4 22.7 26.0 - 13132 8 5 - 14 . 5 16.6 - P r o p e r t i e s o f biomec hanica l pulp. P a p p e r s t l d n 8 5 : R 33 R 3 8 ( 1 9 8 2) - 6 . Sven s k ERIKSS ON , K. E. , JOHNSR UD , S.C. and VALLAN DER , L. D e g r a d a t i o n o f l i g n i n and - l i g n i n model c o m p o u n d s by v a r i o u s m u t a n t s o f t h e w h i t e r o t f u n g u s S p o r o rlchum p u l v e r u l e n t urn. A r c h M i c r o b i o l 1 3 5: 1 6 1 1 6 8 ( 1 9 8 3 ) - - 7. F O R N E Y , L.J ., REDDY , C.A., TIEN , M. a n d A U S T , S.D . T h e I n v o l v e m e n t o f hydroxy l r a d i c a l d e r i v e d from hydrog en p e r o x i d e i n l i g n i n d e g r a d a t i o n by t h e w h i t e r o t f u n g u s P h a n e r o c h a e t e chrysos poriurn. J Biol C h e m 2 57 : 1 1455 1 1462 ( 1 9 8 2) - 8. . 9. W e i g h t loss a n d l i g n i n loss of b i r c h ( Be t ula ve rrucos a ) w o o d w a f e r s ( 2 x 2 0 x 5 0 m m ) determ ined after 2 , 3 and 4 w e e k s o f d e g r a d a t i o n by K 3 a n d four Cel " s t r a i n s. - - - o n e Cel " 8 t r a i n c a n r e m o v e a s m u c h a s 21 2 of the lntltla l a m o u n t o f l i g n i n i n b i r c h w o o d and another s t r a i n 28.5 2 after t h r e e w e e k s. The lignin l o s s e s o b t a i n e d w i t h spruce a n d p i n e wood a r e lower , 6 a n d 1 0 2 r e s p e c t i v e l y a f t e r four w e e k s r o t t i n g but these losses a r e c o n s i d e r a b l y h i g h e r t h a n for e a r l i e r Cel ~ ‘B t r a i n s. Some of the n e w C e T m u t a n t c a n also be u s e d t o d e l l g n l f y s t r a w a n d s u g a r c a n e bagass e t h e r e b y i n c r e a s i n g t h e i r d i g e s t i b i lity for r u m i n a n t s . - - FAISON , B .D . a n d KIRK , T.K . R e l a t i o n s h i p betwee n lignin d e g r a d a t i o n a n d p r o d u c t i o n o f reduce d o x y g e n s p e c i e s by P h a n e r o c h a e t e c h r v s o s p o r i u m. A p p l E n v i r o n M i c r o b i o l 4 6 : 1 1 4 0 1 145 ( 1 9 8 3) - a ) A s a p e r c e n t a g e o f t h e i n :1 a 1 a m o u n t of lignin Table 1 . ERIKSS ON , K . E. and VALLAN DER , L. 5. - K 3 ANI E R , P. and ERIKSS ON , K . E. Methan ol f o r m a t i o n d u r i n g l i g n i n d e g r a d a t i o n by P h a n e r o c h a e t e c h r y s o s p o r 1 urn . Appl M i c r o b i o l B l o t e c h n o l 21 : 9 6 1 0 2 (1 9 8 5) - - 10 RUEL , K . , BARN0 UD , F. a n d E R I K S S O N , K. E. Ultras tructu ral A s p e c t s of W o o d D e g r a d a t i o n b y S p o r o t r l c h u m pulver ulentu m ; O b s e r v a t i o n s - o n S p r u c e W o o d Impregn ated w i t h G l u c o s e . H o 1 z f o r s c h u n g 3 8 : 6 1 6 8 ( 1984) - 11 . JOHNSR UD , S.C. a n d ERIKSS ON , K . E. C r o s s b r e e d i n g o f selecte d a n d m u t a t e d horao k a r y o t l c s t r a i n s of Phaner ochaet e chryso s por 1 u m K 3 : New cellul ase d e f i c i e n t strains with increased ability to degrade l i g n i n. Appl Microbi ol B l o t e c h n o l 2 1 : 320 327 ( 1 9 8 5) - - - - -- - We a r e n o w c o n c e r n e d w i t h the p r o d u c t i o n of echanic al and c h e m i c a l p u l p s from both wood and baga s e e. REFER ENCES 1. -. ERIKSS ON , K. E a n d G0 0DELL , E.W P1 e i o t r o p i c m u t a n t 8 of the wood r o t t i n g fungus Polyporus adust us lacking cellulase , mannan se a n d x y l a n a s e . C a n J M i c r o b i o l . - - - 2 0: 371 378 ( 1974) 2. .- ANDER , P. and ERIKSS ON , K E. Influe nce o f c a r b o h y d r a t e s o n l i g n i n d e g r a d a t i o n by t h e white r o t f u n g u s Sporot r 1 c h u m pu 1 v e ru 1 e n t um • S v e n s k P a p p e r s t l d n 8 : 643 6 5 2 ( 1975 ) - 3 . - - -. ERIKSS ON , K . E a n d VALLAN DER , L Bio m e c h a n i c a l P u l p i n g. In : L i g n i n B i o d e g r a d a t i o n : M i c r o b i o l o g y , C h e m i s t r y and A p p l i c a tions , Vol. II , p p 2 1 3 2 2 4. Eds T K K i r k , T. Higuch i , H m C h a n g . Boca Raton : C H C Press Inc 1980 . - . - .. - -- 103 -soluble rr.. i *.oic anhydr ide copoly mers and relat ively hydro photic po .. iers such » s polyvi nyl acetat e ( PVAc ) , cellu lose ( acetat e, poiye thyl acryla te or polyme thyl methac rylate 1 . The polymu r aixtu. es exhibi t a one phase morpho logy , have a - CHEMICALLY MODIFIED LIGNIN FOR THE USE IN CONTROLLED - RELEASE DEVICES - ' lower cintic al soluti on temper ature ( LCST) of ca . 140°C, are thermo plasti c , and swell in water up to 80 times their dry weight . A.H.A. TINNEMANS* AND H.F. MARTENS TNO INSTITUTE OF APPLIED CHEMISTRY P.O. Box 5009 3502 JA UTRECH T, THE NETHER LANDS These blend s , called Aquall oy polyme rs , have been usee as releas e matrix becau se of their potent ial to contro l G.J. VAN VELDHUIZEN AND P.J. GREIDANUS water sorpti on and sorpti on rate by simply choosi ng the right mixing ratio. TNO PLASTI CS AND RUBBE R RESEAR CH INSTIT UTE P.O. Box 71 , 2nPC AB DELFT, THE NETHER LANDS We have inv ;stigat ec the feasib ility of prepari ng - water swella ble polyme rs compar able with the Aquall oy poly - mers in which type of polyme rs the polyvi nyl esters ABSTRACT are replac ed in part by acylat ed and /or alkyla ted Kraft lignin and organo solv lignin have been modifi ed by acylat ion and alkyla tion in such a way that they can be The brittl eness of these alloys has been reduce d by adding anothe r compat ible polyme r to the mixtur e which has a low glass rubber transi tion temper ature. Severa l exampl es - ALLOY CHARACTERISTICS - Most polyme r mixtur es are not comple tely miscib le and do show phase -separa tion. Howeve r, due to polyme r specif ic - i- bility of ternar y and quater nary mixtur es. intera ctions the mixtur es may become miscib The swella bility of these blends in water, being deriva t lignin and organo solv birch lignin. The r alloys, which are releva nt for contro lled-releas e applic ations, will be discus sed. alloyi ng of approp riate resins. le, formin g under certai n condit ions blends with a one phase morph ology. One -phase mixtures are only thermodynamically stable when 30- 50 times their own weight, provid es a good indica tion of their struct ural homoge neity. 62AG In order to evalua te potent ial matric es for contro lled- 6 -release systems we have determined some water-swelling charac terist ics such as swell ratio, swell rate, - and sorp INTRODUCTION design ing contro lled- -release devices for bioactive materials. Examples are polymer - polyme r comple xes consis ting of opposi tely charge d poly electr olytes which absorb large amount s of water , formin g elast ic hydrog els ( 1 -4 ). Howeve r, these polyel ectrol yte com plexes are insolu ble in organi c solven ts and do not exhibi t therm oplas tic behavi our. As they cannot be proces sed by castin g , mouldi ng or extrus ion , the applic abilit y of hydro gel polyme rs in contro lled releas e system s is limit ed Other disadv antage s are the limit ed number - . of parame ters to adjust optima l releas e profil e ( e g . . equilibrium swelling , swell kineti cs, and pH depend ence of swelli ) ng , and the comple x and costly produc tion techni ques. Likewi se, a hydrogel polyme r matrix is too expensi ve for large- scale applic ations in agricu lture. Recent ly , a new and unique polyme r concep t has been de velope d overco ming roost of the disadv antage ly avail able hydro gel polyme rs. The concep consti tuents. If specif ic intera ctions play have been re- - - is the free energy of mixing and $ m resemb les the volume fract ion of one of the blend criter ium is fulfil led for all blend ratios, becaus e the entrop y of mixing is neglig ible for high molec ular weight blend consti tuents. Specif ic intera ctions may arise from severa l mechan isms but dipole -dipole intera ctions and hydrog en bondin g are the most releva nt intera ctions in of the most promis ing ternar y mixtur es have been tested by measur ing melt index , mechan ical proper ties and glass- rubber transi tion temper ature. cogniz ed as intere sting materi als when — > 0, where AG - th. The thermo plasti c proces sabili ty and flexib ility Polyme r blends with high water absorp tion 2 an import ant role in blend formation , the enthalpy of mixing , AH be m comes negative (exothermic ) , while the AH / relati on is m parabo lic and shows a minimu m . Then , the above miscib ility tion behavi our depend ing on pH and ionic streng hydro gels, which consb - pine charac terist ics of these hydrop hylic polyme used in the format ion of homoge neous blends by solven t will be presen ted showin g the optimi zation of the compat of kraft ives etc. - s of the presen t - t is based on nemoge neous mixtur es of water - ^- mixtur es with exothe rmic heat of mixing . Genera lly , beside s these exothe rmic intera ctions also disper sive or Van der Waals forces betwee n the remaini ng parts of the polyme r consti tuents, not involv ed m specif ic intera ctions play an import ant role in the homoge neous, one - phase blend. These forces contri bute endoth ermica lly to the mixing enthalpy. Howeve r , disper sive forces are indisp ensabl e at the format ion of non-disint egrati ng elast ic hydrog els. They analog ize with the covale nt bonds in cross - linked polymers. We studie d the miscib ility and sorptio n behavi our of a series of binary , ternar y and quater nary blends compris ing modifi ed lignin as one of the consti tuents. For instan ce , optica lly clear films , cast from a 20% w / v solut ion of a 1 : 1 blend of polyst yrene-maletc anhydr ide copolymer (PS MA) , M w 2.105 and an acylated llqnin , swell about 60 times their own weight in distil led water , cf. Figure l . - 105 IONIC STRENGTH 00 WATtP/BUND W/ » As illustrated in Table 1 , neither acidity nor the presence of sodium chloride dramatically influences the swellability of the polyblends comprising an acylated lig rRACUtNTATlON so nin. In - contrast , the swellabilities of Aqualloy polymers - are much more sensitive to changes in pH , choice of elec 4C trolyte or ionic strength. Table 1. Swelling characteristics of films of an alloy of polymethyl vinylether maleic anhydride (PMVE MA) 70 - - £ 70 ..L 0 and acylated organosolv lignin (MA 2240) in 60 00 various aqueous electrolytes 100 - ": PS MA Ratio Figure 1 . Equilibrium sorption of distilled water in a - The phase-separation temperature, also called lower one phase alloy of PS MA/Acylated lignin 30/70 1 . in 1 % w/w NH4OH 125 24 hrs. 19 72 hrs. 7 1 hr. 5 acidified with 2M the degree of protolysis of the anhydride groups. E.g. the acetic acid ( pH 3) - LCST of a 50/50 w/w PS MA/PVAc alloy increases from 40 to . ° 10 min. 2. then in 1 % w/w NaCl , critical solution temperature (LCST), strongly depends on 140 C when only 20% of the anhydride groups are hydrolized Figure 2. The increase is due to formation of hydrogen 3. as under 1 , then in a solution of 1 % w/w bonds generated during hydrolysis of the anhydride groups. CaCl 2 Such increase of LCST permits thermoplastic processing of - Swelling , water/blend w/w MA 2240/PMVE MA - the homogeneous one phase alloy without phase separation , TYPE OF LIGNIN DERIVATIVE - thus holding their interesting water sorption character The swelling behaviour of these binary blends hardly istics. varies utilizing kraft of organosolv lignin derivatives. The swelling behaviour of mixtures comprising anhydride 140 copolymer and acylated lignin with a long aliphatic chain is rather poor. Apparently , these polymers are not com pletely miscible. We have increased the specific inter 100 - actions between the dissimilar polymers by influencing the - hydrophylic/hydrophobic block character of the lignin 00 derivatives. ~hus, introducing ethylene glycol moieties in - the aliphatic chain, e.g. lignin OCCH ,) CO(0CH.,CH ) OCH 3 , 2 ^ ^ high swellabilities are obtained. «0 40 * 10 is 7C DEGREE OF 20 X HYDROr VZCD AWKrDRIDf GROUPS - The kinetics o: the water sorrtion depends strongly on Figure 2. LCST for a 20% w/v solution of 50/50 w/w PS MA/ the fraction of the anhydride grc - PVAc blend in butanone as a function of the per - - centage hydrolyzed anhydride groups in PS MA. - ing ratio, as is illustrated in Figure 1. The transport of - Low molecular weight agents through hydrogels can be des - cribed either by a pore or by a dissolution/diffusion me hanisin. This depends on the nature of the permeating agent,. n the nature of the hydrogel , and on the amount of sorbed . Up to 50% water sorpt * on, the main part of the molecules are bound to the hydrogel polymer , while present as free water . The higher the water ion , the better the pore model describes the transport - active dcients, because the amount of free water ln * c*».e*(7), 06 The water sorption exhibits three staqes: Hydrolysis of the anhydride aroups (I), hydration of the maleic anhy - initial degree of protolysis determines the period of stage I-sorption. At a of protolysis of 100 the overall sorption process stage T is rate determining. The lydrogel and the degree of sorption is a function of alloy atiT s which are protolyzed. *> . In the In the hydrophylic polymer alloys the nature of the (6 ) 1 dride copolymer(II) and osmotic sorpt.on(III) ALLOYING RATIO ater H0T0LYSIS degree sorption starts directly in %, - stage II. The sorption rates in stages II and III can be five orders of magnitude higher than the sorption rates in stage I. These features are of particular interest in designing formations with - - a built in time lag . - - The dependence of the time laq upon the degree of pro tolysis is schematically given in Figure 3. 90 REFERENCES •NinAL DEGREE or PROrOLYSIS 1. CABASSO, I. et al . 40 - ’ , Appl.Pol.Sci. 18, 2137 ( 1974) 2. SHCHORI , E. et al. J .Appl Pol.Sci. 20, 773 (1976) 3. BIXLER , H.J • * MICHAELS, A.S. in: Enc. of Pol.Sci. and Eng. Vol. 10, Now York : Wiley & Sons 40 ( 1969) 4. LYSAGHT , M.I. in: Ionic Polymers , New Yo^k: HaIsted Press, HOLLIDAY , L. ted.) ,( 1975) ’ S , P.J• i U.S. Patent 4 , 322 ,917/ 5. HESLINGA , A • t GREIDANJ 4 ,338 ,417 o nut 6. ZENTNER , G.M. , CARDINAL , J .R • / WEEKS • FEYEN , J• i . SONG , S Z. , J.Pharm.Sci. 68, 970 ( 1979) Figure 3. Influence of the degree of protolysis of the - 7. YASUDA , H• t LAMAZE, C.E • anhydride groups in a 30/70 w/w PS MA alloy on - - * IKENBERRY , L.D• » Die Mal ro . tnolekulare Chemie , 118 , 19 (1968) - the initial period of zero release (time lag). - Such formulations might be advantageously used in agri culture , when the active material is only needed several weeks after application. - GLASS RUBBER TRANSITION TEMPERATURE, Tg By using the Aqualloy alloying techni* e modified lignin can be used in the formation of homogeneous blends. Generally , binary polymer alloys appear to be fairly brittle. This behaviour may be caused by a too low average molecular weight of the blend components. The brittleness of the swellable, binary blends could be reduced by adding another compatible polymer to the mixture, which has a low - - Tg value (e.g. PVAc (Tg « 28°C), and vinyl acetate vinyl laurate copolymers). An example of the sorption behaviour of ternary and quaternary blends is compiled in Table 2. Films , cast from 20% w/v blend solutions in butanone , are optically clear , flexible and fairly strong , and possess excellent swelling properties. MECHANICAL PROPERTIES - The blends were tested on » their thermoplastic process ability and flexibility by measuring tensile properties, - - melt index and glass rubber transition temperature. The data obtained , as examplified in Table 2 , indicate that no high demands can be made on the mechanical properties of tiie blends. However , with regard to the evaluation of - potential matrices for controlled release devices , this is of minor importance. Table 2. Swelling characteristics and mechanical properties - of somp alloys containing modified lignin (L OR) - - L-OR/PMVE-MA/PVAc/ MA /PVAc PVAc- VL Ratio in % w/w L OR/PS Swelling , water/blend w/w 33/33/33 33/32/25/10 1 % w/w NH OH 10 min. 10 dist. H O 24 hrs. 2 N/rim 45 55 12.7 5 10.5 4 ^ strength Tensile - - Strain at break E modulus - % N/mm ^ 1200 0.53 2050 107 again deposit or form pitch speck in paper product ^ . In order to understand the behavior of pitch desopition , a simple device of rotating felt was developed , which is proven to be ? useful tool for predicting pitch deposition. On the other hand the device itself is also useful for study on behavior of other organic colloids in papermaking stock. ROTATING FELT TC STUDY THE BEHAVIOR OF ORGANIC COLLOIDS IN PAPERMAK!NG STOCK TERUNOBU FUKUI and AKIO OKACAWA JAPAN PULP AND PAPER RESEARCH INSTITUTE , 5 13 TOKODAI , TOYOSATO- MACHI , TSUKUBA GUN , IBARAKI 300 26 , JAPAN - - - ROTATING FELT DEVICE ABSTRACT Behaviour and interactions of organic colloids , such as fines , fillers , polymers and pitch , in papermaking process play an important role in and properties of process paper operation . the To understand nature of aggregaproducts tion and deposition of colloidal organic particles , simple device consist of a beaker and rotating felt was developed in our laboratory. Potential of pitch deposition in papermaking machinary can easily predicted using this device. Although this device was developed primarily to study the nature of pitch particles , it can be used for studying other colloidal system. Appli cation of rotating felt device to suspensions of latex and hot melt is discussed. Schematic diagram of rotating felt is shown in Fig. 1. Felt or felt-like material of 30 mm wide is forme! into a roop , which can be rotated by a Teflon rotor at the speed of 47cm /sec. Hilf of felt roop is dipped into a suspension to be studied . The amount of deposition on felt can easily determined by light or nbsorption turbidity measurement of remaining suspension . Teflon Roller - Beaker Suspension KEYWORDS: Felt , Pitch , Latex , Hot Melt , Felt Deposition Teflon Rod INTRODUCTION Major component of papermaking stock is wood fiber , which is hardly considered to be colloidal particle. However there are many kind of colloid al particles in papermaking stock. For example , fines of wood fiber , polymers , latex and pitch particles are in the range of colloids. Thus it is important to understand the behavior of these collidal particles , particularly to understand interactions among themselves and with other particles including non colloidal materials. Retentions of fines and fillers during paper making process depend not only on surface chemical properties of particles and wood fibers , but also network structure of fiber matrix. Papermakers wish to have maximum retention without aggregation of particles , so that particles are well distributed in a bulk of paper. Higher retention and good dispersion are two opposite properties required , thus difficult to achieve both simultaneously. Pitch , whatever it is defined , usually exist as colloidal form in pulp and paper making process. It can stick to any part of machinary to form a deposit or aggregate into large particles which Fig.l. Schematics of Rotating Felt Device . - - - 100 T T T 75 *c 50 o > l/ o Q 0) O 25 O A - 5D A 8- 50 E- MC 0 2.0 l 4.0 6.0 P H 80 10.0 Fig.2. Effect of pH on Pitch Deposition . A , B are pitchs taken kraft from hardwood bleachery , and E from softwood kraft paper machine. 109 DEPOSITION OF PITCH Deposition of pitch gradually increases with a time of rotation. If the rotation of felt is ntinued , eventually all pitch could be ^ deposited on the felt. However the rate of deposition varies with many conditions , such as chemical nature of pitch , temperature , pH , added electrolytes etc . The effect of pH on pitch deposition is shown in Fig. 2. Distinctive difference in the behavior of pitch deposition was observed . Pitchs A and B were ones from bleachery of hardwood kraft pulps , and pitch E from softwood kraft paper machine. Softwood pitch did not affected by pH variation. Hardwood pitch , on the other hand , influenced by pH chang e considerably. Similar distinction in pitch deposition behavior was also observed with the change in temperature. Sequential change in pitch deposition during five bleaching stages(C E-H-E D ) of hardwood pulp is shown in Fig. 3. Deposition tendency of pitch increases as the bleaching sequence progresses , reaching maximum at the last chlorine dioxide bleaching. Deposition test of pitch in bleach effluent revealed that deposition ability undergo oscillatory change with bleaching sequence. Fig.3. Effect of pH on Deposition of Pitchs from Mill A. 1C to 5D designates Bleaching Sequence. - EHAVIOR OF LATEX nthetic latex has been accepted for their ^ application to many fields , including pulp and paper industry. Thus it is important to know how they behave in the changing environment of pulp and paper making process. Fig. 4. is an example of latex deposition measured by rotating felt device. Measured deposition was parallel to the change in mobility of latex , not influenced by the surface characteristics of felt. ' AI 7 ( S 04 ) 3 Cone ( mmol /I) Fig.4. Deposition of Latex on Felt , and Electrokinetic Properties of Latex and Felt. BEHAVIOR OF HOT MELT Sticky material in recycled paper was transformed into col.oidal particles during the courseof re pulping. Fig. 5. shows the effect of Alum addi tion on the deposition of hot melt suspension on a felt. Deposition was very close ly related to the surface potential of hot melt parti cles. - 60 Deposition 45 MOO 'E ^ u ! > cn +50 % £ 5 u. 3 oo HM c Felt 9 30 0 a These examples indicate that the rotating fe i c device is an useful tool for studing nature of organic colloids. 110 to X S2 I «0 o o a -50 * o* 15 » 0) NJ 0 a o 10 4 10 ? 1 100 AI J ( S 04 ) j Cone ( mmol / 1) - Fig. 5. Deposition of Hot Melt Particles on Felt , and Electrokinetic Properties of Particles and Felt . deposit or form pitch speck in paper products. In order to understand the behavior of pitch desopition , a simple device o rotating felt was developed , which is proven to Ke a useful tool for predicting pitch deposition . On the other hand the device itself is also uset for study on behavior of other organic colloi v.* a in papermaking stock. again ROTATING FELT TO STUDY THE BEHAVIOUR OF ORGANIC COLLOIDS TN PAPERMAKING STOCK TERUNOBU FUKUI and AKIO OKAGAWA JAPAN PULP AND PAPER RESEARCH INSTITUTE , 5 13 TOKODAI , TOYOSATO MACHI , TSUKUBA GUN , IBARAKI 300- 26 , JAPAN - - - ABSTRACT Behaviour and interactions of organic colloids , such as fines , fillers , polymers and pitch , in papermaking process play an important role in process operation and properties of paper To unde stand the nature o aggrega products. tion and deposition of organic colloida 1 particles , simple device consist of a beaker and rotating felt was developed in our laboratory. Potential of pitch deposition in papermaking machinary can easily predicted using this device. Although this device was developed primarily to study the nature of pitch particles , it can be used for studying other colloidal system. Appli cation of rotating felt device to suspensions of latex and hot melt is discussed. ROTATING FELT DEVICE Schematic diagram of rotating felt is shown in Fig . 1. Felt or felt like material of 50 mm wide is formed into a roop , which can be rotated by a Teflon rotor at the speed of 47cm /sec . Half of felt roop is dipped into a suspension to be studied . The amount of deposition on felt can determined easily by light absorption or turbidity measurement of remaining suspension. - Teflon Roller Beaker Suspension KEYWORDS: Felt , Pitch , Latex , Hot Melt , — Felt Deposition Teflon Rod INTRODUCTION Major component of papermaking stock is wood fiber , which is hardly considered to be colloidal particle . However there are many kind of colloid al particles in papermaking stock. For example , fines of wood fiber , polymers , latex and pitch particles are in the range of colloids. Thus it is important to understand the behavior of these collidal particles , particularly to understand Interactions among themselves and with other particles including non colloidal materials. Retentions of fines and fillers during paper making process depend not only on surface chemical properties of particles and wood fibers , but also network structure of fiber matrix. Papermakers wish to have maximum retention without aggregation of particles , so that particles are well distributed in a bulk of paper. Higher retention and good dispersion are two opposite properties required , thus difficult to achieve both simultaneously. Pitch , whatever It is defined , usually exist as colloidal form in pulp and paper making process. It can stick to any part of machinary to form a deposit or aggregate into large particles which Fig. l. Schematics of Rotating Felt Device. - - - 100 T 75 *c 50 o «/> o Q 0) KI n o 5 (SO «), Cone (mmol/ l) AI, i Fig .4. Deposition of Latex on Felt , and Electrokinetic Properties of Latex and Felt. )F HOT MELT erial in recycled paper was transformed • idal particles during the course of re Fig. 5 shows the effect of Alum addi he deposition of hot melt suspensi on on Deposition was very closely related to e potential of hot melt particles. . - 60 + 100 45 E ‘SO % u. £ u > > E in • 3 c O O (D X 0 2 30 £ 5X V) o o Q mples indicate that the rotating felt an useful tool for studing nature of l 1 oids. * a o & 15 -50 * » > at ISJ 0 Fig. 5. - 1 10 ’ 10 AI 3(S04)J Cone ( mmol. Il a o 100 Deposition of Hot Melt Particles on Felt , and Electrokinetic Properties of Particles and Felt . t l t I DEPOSITION OF PITCH DeposiCion of pitch gradually increases with a time of rotation. If the rotation of felt is be i all pitch eventually could ^ntinued , posited on the felt. However the rate of deposition varies with many conditions , such as chemical nature of pitch , temperature , pH , added electrolytes etc. The effect of pH on pitch 2. Distinctive deposition is shown in Fig. difference in the behavior of pitch deposition observed . Pitchs A and B were ones from I was bleachery of hardwood kraft pulps , and pitch E from softwood kraft paper machine. Softwood pitch did not affected by pH variation. Hardwood pitch , on the other hand , influenced by pH change Similar considerably. distinction in pitch deposition behavior was also observed with the | change in temperature. Sequential change in pitch deposition during five bleaching stages(C-E H-E D ) of hardwood pulp is shown in Fig. 3. Deposition tendency of pitch increases as the bleaching sequence progresses , reaching maximum at the last chlorine dioxide bleaching . Deposition test of pitch in bleach effluent revealed that deposition ability undergo oscillatory change with bleaching sequence. I F i g. 3 . Effect of pH on Deposition of Pitchs from Mill A. 1 C to 5D designates Bleaching Sequence. - - I EHAVIOR OF LATEX :hetic latex has been accepted for their application to many fields , including pulp and aaper industry. Thus it is important to know how ;hey behave in the changing environment of pulp * nd paper making process. Fig. 4. is an example latex deposition measured by rotating felt levice. Measured deposition was parallel to the change in mobility of latex , not influenced by he surface characteristics of felt. ^ AI 2 ( SO « ) 3 Cone ( mmol / l) Fig.4. Deposition of Latex on Felt , and Electrokinetic Properties of Latex and Felt . EHAVIOR OF HOT MELT Jticky material in recycled paper was transformed nto c olloidal particles during the course of re wiping. Fig. 5. shows the effect of Alum addi i on on the deposition of hot melt suspensi on on felt. Deposition was very closely related to ne surface potential of hot melt particles. 60 examples indicate that the rotating felt • vice is an useful tool for studing nature of rganic colloids. b 1 > CO ^50 u. Ea. 45 £ o o c . 4) N» A o 100 5 Fig . 5. Deposition of Hot Melt Particles on Felt , and Electroki tu tic Properties of Particles and Felt , CHEMICAL STRUCTURE AND REACTIVITY O F THE MIDDLE LAMELLA LIGNIN i n t e r e s t t o be able t o a n a l y s e Isolated middle lamella . Direct isolation i s , however , a very tedious procedure which gives only small . Different a m o u n t s o f m a t e r i a l ( Bailey 3) ULLA WESTERMARK f r a c t i o n a t i o n t e c h n i q u e s h a v e therefore been u s e d t o s e p a r a t e f r a c t i o n s e n r i c h e d i n middle SWEDISH FOREST PRODUCTS RESEARCH L A B O R A T O R Y BOX 56 0 A S 11 A 8 6 STOCKHOLM , SWEDEN lame 11 a. W h i t i n g e t al. ( A ) have u s e d a - gradient " density separation ” t e c h n i q u e t o e n r i c h middle l a m e l l a based o n the lower d e n s i t y of l i g n i n r i c h m a t e r i a l. U s i n g t h i s t e c h n i q u e , a fraction - w i t h h i g h lignin c o n t e n t a s s u m e d t o c o m e from the m i d d l e lamella w a s s e p a r a t e d . T h e b a s i s o f ABSTRACT T h e i s o l a t i o n of a m i d l e lamella f r a c t i o n by a s i e v i n g t e c h n i q u e i s d e s c r i b e d . A n a l y t i c a l d a t a f o r this f r a c t i o n i s compared w i t h pub - the d e n s i t y g r a d i e n t t e c h n i q u e i s that t h e m i d d l e lamella h a s a h i g h e r degree o f l i g n i f i - l i s h e d d a t a for a middle l a m e l l a f r a c t i o n c a t i o n than o t h e r p a r t s o f the w o o d . Isolated by the d e n s i t y g r a d i e n t f r a c t i o n a t i o n H a r d e l l e t al. ( 5) developed a t e c h n i q u e based o n s i e v i n g t o i s o l a t e different w o o d ele t e c h n i q u e . T h e c o n r e n t of p hydroxyphenyl - - propane u n i t s and t h e b r o m i n a t i o n b e h a v i o u r o f - m e n t s from s p r u c e , i n c l u d i n g a f r a c t i o n e n r i c h e d i n middle lamella / p r i m a r y w a l l m a t e r i a l . T h i s t e c h n i q u e has been further developed - the m i d d l e l a m e l l a f r a c t i o n s were s t u d i e d . In conflict with earlier published results , no - i n d i c a t i o n s of p hydroxyphenylpropane u n i t s o r by W e s t e r m a r k (6) and a f r a c t i o n of m i d d l e lamella p a r t i c l e s h a s been isolated. T h e middle o f a l o w e r b r o m i n a t i o n a b i l i t y of the middle lamella lignin t h a n of the w h o l e w o o d w e r e lamella p a r t i c l e s c a n be isolated e i t h e r from wood o r from thermomechanical p u l p. T h e a d v a n o b t a i n e d i n o u r sample . It w a s noted t h a t the - - d e n s i t y s e p a r a t e d m a t e r i a l had many p r o p e r t i e s t a g e o f t h i s t e c h n i q u e i s that the m i d d l e s i m i l a r t o c o m p r e s s i o n w o o d . The p o s s i b i l i t y lamella fragments c a n be r e c o g n i z e d a n d checked under a m i c r o s c o p e. F i g . 1 s h o w s a p i c t u r e o f - that t h i s can be due t o e i t h e r a c o n t a m i n a t i o n of c o m p r e s s i o n wood l i g n i n in the d e n s i t y - - s e p a r a t e d m a t e r i a l or that the t e c h n i q u e s s e p a r a t e different p a r t s of the middle lamella i s d i s c u s s e d. - KEYWORDS : M i d d l e lamella , p hydroxypheny 1 propane , b r o m i n a t i o n , l i g n i n - The r e a c t i v i t y a n d c o m p o s i t i o n of t h e middle lamella and o u t e r c e i l w a l l s i n softwood f i b e r s a r e i m p o r t a n t for the d e f i b r a t i o n o f w o o d and a l s o t o a c e r t a i n d e g r e e for the s u r f a c e pro p e r t i e s o f pulp fibers. UV s p e c t r o p h o t o m e t r i c - - F i g u r e 1. a n a l y s i s of t h i n wood s e c t i o n s has s e r v e d a s the b a s i s for m u c h of the p r e s e n t k n o w l e d g e - about the c o m p o s i t i o n a n d r e a c t i v i t y o f the c o m p o u n d m i d d l e lamella. T h e UV technlque also - showed that t h e middle lamella reacted d i f f e r ently from the s e c o n d a r y wall d u r i n g a l k a l i n e - - pulping processes ( Procter e t al . 1 ). Differ e n c e s i n the c h e m i c a l s t r u c t u r e of t h e lignin i n different p a r t s of the fiber were a l s o found by t h i s t e c h n i q u e ( Yang e t a l 2) H o w e v e r , t h e . . - UV t e c h n i q u e Involves several a s s u m p t i o n s whose c o r r e c t n e s s Is difficult t o verify . To c o n f i r m t h e UV result and t o obtain m o r e d e t a i l e d information o n the s t r u c t u r e and r e a c t i v i t y o f - the m i d d l e lamella it would be of g r e a t The appearance o f the middle lamella fragments . S c a n n i n g electron m i c r o scopy . Isolated middle lamella p a r t i c l e s. By S E M and light m i c r o s c o p y i n v e s t i g a t i o n s it has been established that a c o n s i d e r a b l e p a r t o f the p a r t i c l e s also c o n t a i n s t h e middle lamella cell corners. The fraction h a s a l i g n i n c o n t e n t of A 3 Z l i g n i n a s m e a s u r e d by Klason a n a l y s i s and methoxyl c o n t e n t. T h e l i g n i n i n the t i s s u e Isolated by t h e density g r a d i e n t technique i s m u c h d i f f e r e n t from t h e r e s t of the wood l i g n i n (Whiting e t al . 7 ). It has a lower methoxyl c o n t e n t and can c o n t a i n u p t o one third of p hydroxypheny 1 - - 113 I p r o p a n e u n i t s. I t a l s o 6 h o w s a d i f f e r e n t bromi - nation behaviour from that of the rest of the •• - In the present work , the p hydroxypheny 1 propane units and the bromination behaviour of middle lamella fragments isolated by the above mentioned technique of Westermark have been - l y s l s a n d n i t r o b e n z e n e o x i d a t i o n. - w o o d o r i n t h e m i d d l e l a m e l l a f r a c t i o n. I n t h e - nitrobenzene oxidation , a considerable amount - of p hydroxybenza 1dehyde was also detected from the compression wood whereas only traces were studied. The content of p hydroxypheny 1 propane units in the lignin has been analysed by acido - p r e s s i o n w o o d s a m p l e ( c o m p o u n d s 3 , 8 , 9). N o n e of these was , however , detected in the whole o o d l i g n i n ( S a k a e t a l. 8). - - products originating from p hydroxypheny 1 propane units were identified in the com - found in the whole wood and in the middle l a m e l l a s a m p l e. T h i s m e a n s t h a t t h e c o n s i d e r - Compression wood contains a lignin with a able amount of p hydroxyphenylpropane units low raethoxyl content and a considerable amount indicated in the density separated middle - - - - lamella sample could be confirmed in the of p hydroxyphenylpropane units and was there f o r e i n c l u d e d a s a c o m p a r i s o n i n t h e a n a l y s i s. sample separated by the technique described in The chromatograms from the acidolysis mixture t h i s p a p e r. a r e s h o w n i n F i g. 2. S e v e r a l d e g r a d a t i o n not Bromination of wood has recently attracted interest since it has been used for lignin determination by the SEM and - TEM EDXA tech - . The response to bromination of © n i q u e s ( 7) different morphological parts of the fiber is (D therefore of Importance for the quantification o f t h e l i g n i n d i s t r i b u t i o n o v e r t h e c e l l w a l l. wood is The lignin separated by the density fractiona - tion technique brominates to a lesser degree t h a n t h e w h o l e w o o d l i g n i n. T h e b r o m i n a t i o n b e h a v i o u r o f o u r f r a c t i o n i s s h o w n i n F i g . 3. D ( l JJL^ j 20 40 60 g bromine g lignin min O whole wood x middle lamella A compression wood 05 - © © is # middle lamella fraction • © 04 03] A A“ 3 5 A 0.2 - IUJS LJJJL ,JL 20 » 40 60 0.1 mm S *; © »< © 1 - ® 7 9 11 13 15 17 time . nours compression Figure 3 wood IS . I n c o r p o r a t i o n o f b r o m i n e a t 60°C into the lignin of normal wood , middle Lamella and compression wood . i a _ © ® ® I IIJL i!'jib %UJuULLi » t jure .. • 0 40 From the curves it is obvious that the lignin in the middle lamella fraction isolated by our technique brominates to the same extent as the 60 Gas chromatograms of the products from M c 1d o 1 y s i6 of whole wood , middle lamella and compression wood l i g n i n. P r o d u c t ( 3 ) i s p h y d r o x y b e n z a i d e h y d e , ( 8 ) i s 2 h y d r o x y l ( <« l y d r o x y p h e n y l ) l p r o p 4i m n e a n d (9 ) 1 6 3 h v d r o x y l (4 h y d r o x y p h e n y l ) 2 p r o p a n o n e. - - - - 114 mm - - - -- - - - --- -- w h o l e w o o d l i g n i n. C o m p r e s s i o n w o o d l i g n i n i 6 , h o w e v e r , b r o r o l n a t e d t o a .e s s e r e x t e n t . T h e value for the compression wood is in fact simi Hr to the v a l u e o b t a i n e d b y S a k a e t a l . ( 8) - lor the density separated middle lamella. A similar reactivity of the middle lamella and - cell wall lignin to bromination would mean that the lignin concentration in the middle lamella measured by bromlnation EDXA would be consider ably lower than has earlier been measured by - - - t h e U V t e c h n i q u e (9). I t i s o b v i o u s f r o m t h e results of the acidolysis and bromination that the middle lamella fraction isolated by the technique described here reacts quite differ - ently from the fraction isolated by the density fractionation technique. In fact , the density separated middle lamella behaves in a similar manner to the compression wood in our study. The possibility either that this can be due to a contamination - of compression wood lignin in the density separated material or that the techniques - separate different parts of the middle lamella is discussed. REFERENCES 1 . 2. . P R O C T E R , A R ., Y E A N , W.Q. a n d C O R I N G , D. A .I. T h e t o p o c h e m i s t r y o f d e l i g n i f l c a tion in kraft and sulphite pulping of s p r u c e w o o d . P u l p P a p e r H a g . C a n. 6 8 : 4 4 5 ( 1 9 6 7) - Y A N G , J . M. a n d G O R I N G , D . A.I . A c o m p a r i s o n of the concentration of free phenolic hydroyl groups in the secondary wall and m i d d l e l a m e l l a r e g i o n s o f s o f t w o o d s. P u l p P a p. C a n. 7 9: T R 2 5 ( 1 9 7 8) - 3. B A I L E Y , A .J . - Lignin in Douglas fir , com p o s i t i o n o f t h e m i d d l e l a m e l l a. I n d u s t r i a l a n d E n g i n e e r i n g C h e m i s t r y 8( 1 ): 5 2 5 5 - ( 1 9 3 6) 4. - W H I T I N G , P., F A V I S , B . D., S T G E R M A I N , F.G.T. a n d G O R I N G , D.A.I. F r a c t i o n a 1 separation of middle lamella and secondary wall tissue from spruce wood . J. Wood C h e m . T e c h n o l . 1 : 2 9 4 2. - 5. H A R D E L L , H .- L., L E A R Y , C.J ., S T O L L , H . a n d . s p r u c e . S v e n . P a p p e r 9 t i d n. 8 3 :4 4 4 9 WESTERMARK , U Variations in lignin structure in defined morphological parts - ( 1 9 8 0) 6 . of W E S T E R M A R K , U. T h e o c c u r r e n c e o f p h y d r o x y pheny 1 propane units in the mldd 1 e 1ame 11a l i g n i n o f s p r u c e ( P i c e a a b l e s). T o b e - - - p u b l i s h e d i n W o o d S c i . T e c h n o l . 1 9 8 5. 7. . W H I T I N G , P a n d G O R I N G , D.A . I . C h e m i c a l characterization of tissue fractions from the middle lamella and secondary wall of b l a c k s p r u c e t r a c h e l d s. W o o d S c i . T e c h n o l . 1 6 : 2 6 1 2 6 7 ( 1 9 8 2) 8. S A K A , S.v W H I T I N G , P. , F U K A Z A W A , K . a n d G O R I N C , D. A . I. C o m p a r a t i v e s t u d i e s o n lignin distribution by UV mclcroscopy and b r o m i n a t i o n c o m b i n e d w i t h E D X A. W o o d S c i . T e c h n o l . 1 6 : 2 6 9 2 7 7 ( 1 9 8 2) - 9. . S A K A , S , T H O M A S , J .R. a n d G R A T Z L , J .S . Lignin distribution in Douglas flr and loblolly pine as determined by energy d i s p e r s i v e x r a y a n a l y s i s. I n t e r n a t I o n a 1 Symp W o o d a n d P u l p i n g Cheta. S t h . I : 3 5 5 1 ( 1981) - . - - 115 18 H 2 O only analogical interpretation , hydrolysis and 8 hydroxylation , was made without adequate experimental evidence for the cleavage mechanism of 8 0 4 substructure to give arylglycerol (Fig. 1 , pathway A). - - PATHWAYS AND M NANISM OF DEGRADATION FOR ARYL GLYCEROL 8 APYL ETHER SUBSTRUCTURE MODELS BY Phanerochaete chrysosporium AND Coriolus versicolor -- -- T. HIGUCHI , M . SHIMADA , T. UMEZAWA AND S. KAWAI £ WOOD RESEARCH INSTITUTE , KYOTO UNIVERSITY , (IV) OH UJI , KYOTO 611, JAPAN ABSTRACT It was found by isotopic experiments with lig ninolytic culture of P. chrysosporium that aryl glycerol 8 aryl ether models were cleaved between Co and C8 of the glycerol side chain to give ben zyl alcohol derivatives (C6Ca) and glycol (CB Cy) without hydrogen abstraction , and that ligninase reaction was consistent with the in vivo experi ment results. Seme of the arylglycerol 8 ary 1 ether models gave the arylglycerols via the cyclic car bonate or formate of the arylglycerols by the cleavage of 8 ehterated aromatic rings mediated by other ligninases. - -- - - - -- - - -- KEYWORDS: Arylglycerol 8 ary 1 ether , Ligninase , P. chrysosporium , C. versicolor , Aromatic ring cleavage -- - - -- - -- - -- - - - - - - - - - - - -- - - (V) Figure 1. Degradation pathways of non phenolic arylglycerol 8 ary 1 ether models by P. chrysosporium. This paper deals with the degradation pathways of 8 0 4 substructure models by P. chrysosporium and C. versicolor , and some reaction mechanism of C C and ether cleavage of lignin substructure models mediated by ligninase. RESULTS AND DISCUSSION in vivo Experiments P. chrysosporium and C. versicolor were cul tured in ligninolytic condition and the 8 0 4 models were added as DMF solution into the 5 ,6 day cultures which showed a strong ligninolytic activity , and flushed with oxygen. Usually the degradation products were extracted with ethyl acetate , acetylated , separated by TLC , and ana lyzed by GC MS and NMR. When we started degrada tion study on 6 0 4 models using P. chrysosporium arylglycerol (II), guaiacol (IV ) , C6 Ca (benzyl alcohol) derivatives (III) and guaiacoxyethanol (V) had been identified as degradation products of arylglycerol B guaiacy 1 ether ( I) by P. chry sosporium (Fig. 1), but no informations had been obtained on CB Cy fragment compounds which could be formed as counterpart compounds for C6Ca de rivatives , nor the formation mechanism of aryl glycerol. Since CB Cy fragment compounds which could be derived from arylglycerol side chain such as gly col derivatives are supposed to be difficult to detect by further metabolism we synthesized a trimer composed of 8 0 4 and a O y substructure , i.e • 9 y benzyl ether of 6 0 4 substructure model (VI ) as substrate (11). As degradation product benzyloxy ethanol (VIII) , a CB Cy fragment com pound was identified for the first time , in addi tion to a C6Ca derivative ( III) and an arylqlyc erol derivative (VII ). Thus , we now know that the arylglycerol moiety of 8 0 4 models is cleaved between Ca and CB to give a C6Ca derivative (III ) and glycol ( VIII) (CB Cy fragment compound ) via - -- -- - - - - -- OEt (III) -- INTRODUCTION The arylglycerol 8 ary 1 ether bond (8 0 4 sub structure) is the most frequent interphenylpro pane linkage which roles to connect main lignin substructures such as 8 5 , 8 8 ’ , 8 1 in lignin macromolecule. It is , therefore, very important related to the depolymerization of lignin to elu cidate the degradation mechanism for 8 0 4 sub structure by lignin degrading fungi which cleave 8 0 4 linkage at the initial stage of lignin ca tabolism. Indeed , many researchers ( 1 7) have at tempted to elucidate the cleavage mechanism for 6 0 4 linkage using several lignin degrading mi croorganisms, and recently the enzyme which cat alyzes Ca CB cleavage of 8 1 substructure models as well as 8 0 4 models was isolated from a lig nin degrading fungus , Phanerochaete chrysosporium ( 8 10 ). The results so far obtained by these research ers could be summarized as illustrated in Fig. 1. Earlier studies ( 1 4 ) showed that guaiacylglycer °ol1 and guaiacol were formed from veratrylglycer 8 guaiacy 1 ether in the cultures of several Hgnin degrading fungi. Later , the formation of these compounds were confirmed in the ligninoly tic culture of P. chrysosporium (5 7). However , in earlier investigations without used and -- 0CH3 OEl (II) - - - -- - -- - - - - - - -- -- -- - - - - -- - 117 a pathway (pathway B , Fig . 2). - The results clearly indicated that CB hydroxyl ation and hydrolysis of 6 0 4 models as suggested by earlier papers (1 4) did not occur in the for mation of arylglycerol. So , as the next step of the investigation we synthesized arylglycerol 18O guaiacyl ether (1 6 180) as substrate (15). MS analysis of the aryl glycerol and guaiacol isolated from the ligninoly 18 tic culture showed that 0 was retained almost 100% at C8 of the arylglycerol and hydroxyl group of the guaiacol , respectively. The result clearly -- - - - - - (VIII) (III) (VI) - Figure 2. Degradation pathways of a trimer com posed of B 0 4 and a O y substructures by P. chrysosporium. We propose that at least some of the C6Ca com pound (III) is produced by the Ca CB cleavage which does not involve arylglycerol (VII) ( path way B , Fig. 2) , in addition to the C6Ca compound (III) produced via Ca CB cleavage of arylglycerol (VII) previously formed by other pathways ( path way A , Fig. 2). Because we found that is incorporated into the benzyl alcohol derivative (III) derived from B 0 4 substructure model , but is not incorporated into the benzyl alcohol de rivative from arylglycerol (VII) used as sub strate in ligninolytic culture of P. chrysospor ium. It seems that the incorporation of 8O into benzyl alcohol derivative (III) from B 0 4 sub structure models (VI) can not be explained by the mechanism of Ca CB cleavage proposed by Kirk et al., (9), incorporation of oxygen into CB as in the Ca CB cleavage of B l substructure models. To elucidate the mechanism for the formation of arylglycerol from B 0 4 substructure models we synthesized Ca and CB double deuterated B 0 4 model compound with (VI a , B 2D) and without a 0 y bond ( IX a , B 2D) and used as substrates for ligninolytic cultures of P. chrysosporium (11 , 12). We found that the isolated arylglycerols , (VII cx , B 2D) and (II a , B 2D) , retained deute rium almost 100%. We (13 , 14) further investi gated the degradation of B 0 4 model (I) under 16o with H 18o. 180 was not incorporated into ~ ? 18 CB of arylglycerol from » O , whereas about half 2 of the Ca oxygen of the glycerol was derived from 18 H 2 O and the other was from the Ca oxygen of substrate (I). The results are summarized and illustrated in Fig. 3. -- -- - - - - - 1802 -- ! -- - - - - -- - - - ^ -- - - - - - -- 18 o indicated that the cleavage occurred between and guaiacol in the formation of arylglycerol. The 180 could be reasonably ex formation of guaiacol plained as derived from an intermediate hemiketal which could be formed by the direct Ca CB cleavage of B 0 4 models mediated by the ligninase charac terized by Kirk et al (9). Two possible mechanisms which involve and/or do not involve aromatic ring cleavage are supposed for arylglycerol formation. Hence , we first searched for ring cleavage products in the culture with B 0 4 models and could identify an unknown compound , which always appeared as a peak with a little later retention time than that of arylglyc erol in GC MS analysis , to be a 8 y cyclic carbon ate of arylglycerol (X). Our interest was then focussed on the origin of the carbonate carbon of the compound. We syn thesized 4 ethoxy 3 methoxyphenylglycerol 8 guaia col 33C ether (I C) and added to the ligninoly tic culture of P. chrysosporium (16). The carbonate was isolated from the culture and analyzed by MS. The spectrum is shown in Fig. 4. OEl *a ioo 0E! .- ”3 - . . ( VI l - .. n ft JD ) K r i l C M, / » ' t K rU) ( Mil m 111 f igure 3 . Degradation pathways ( based or» . sotopic experiments) of 4 et hoxy 3 mctr. >. » hon .- - - -- ylglycerol 0 ary 1 ethers by P. chrv sosporlum -- - -- -- -^ 250 in z UJ Z 0 - - M 310 *S £ so - - 101 AUTHENTIC { ~ 100 181 UJ > METABOLIC 311 *5 < SO 251 UJ cc I L 0 200 2 S0 ml 2 4 300 Figure 4. Mass spectra of the cyclic carbonate of 4 ethoxy 3 methoxyphenylglycerol ( X) (acetate). * : 1 -*C It was clearly shown that the carbonate carbon was derived from guaiacyl ring carbon , indicating that the ring cleavage of 8 etherated guaiacol occurred In a separate investigation ( 17) using C. versicolor with 4 ethoxy 3 methoxyphenylglycerol P quaiacol 13C ether ( I 13C) the cyclic carbonate (X 13C ) was also identified and confirmed that the carbonate cartion was derived from the guaiacyl ring . urthermore , it was found that the cultures of be * P. chrysosporium and C. versicolor with -- - - 118 - - - - - - CMj - -- - CHj I - -- - CHO - - ^ PO -- - - - - -- - --- - -- -- 4 ethoxy 3 methoxyphenylglycerol 0 2 ,6 dimethoxy phenyl ether ( XI ) gave 4 ethoxy 3 methoxypheny 1 glycerol y f ;rmate ester (XTI), and that the for mate carbon was derived from 2 ,6 dimethoxypheny 1 ring by using 4 ethoxy 3 methoxypnenylglycerol 6 2 ,6 dimethoxyphenol C ether (XI 13C) as sub strate (17). It was further shown that both the - - - - - --* * - -- - - - cyclic carbonate and y fornate of arylglycerol , (X ) and ( XII) respectively , were degraded to give arylglycerol (II) in the cultures. These results as shown in Fig. 5 , clearly indicated that some of the arylglycerol is formed by the cleavage of aromatic ring of 0 etherated aryl groups. - -- erol S syringaldehyde ether by versicolor. The formation of the latter compound could be explained by secondary connection of glycol to 4rethoxy 3 methoxybenzoic acid , both of which could be formed by C Cfl Cleavage of 4 ethoxy 3 methoxyphenylglyc a fcs erol 0 syringaldehyde ether by the fingus. -- - - -- -- - in vitro Experiments Recent research on lignin biodearadation has rapidly been progressing towards elucidation of its molecular mechanism of a hemoprotein ligninase isolated from chrysosporium (6 - 10). We have recently established ( 24 26) the simple biomimetic model system with the iron porphyrin catalyst which exhibits an important oxygenase action of the lig ninase. Here , we report one electron transfer re action mechanism to rationalize apparently differ ent types of oxidations with lignin and its related compounds on the basis of a lines of evidence ob tained in the in vivo and in ' itro systems. The culture filtrate of 6 ,7 day ligninolytic cultures of chrysosporium was concentrated by a membrane filter , dialyzed and usea as a crude en zyme solution for the oxidative cleavage reaction of lignin substructure models , deuterated aryl glycerol 0 ary 1 et.iers , (VI a , B 2D) and (XIII a ,6 2D) , and 1 ,2 diarylpropanes , (XVI 0 D) ar.i ( XVI u D) , as shown in Figs. 7 and 8 , respectively . - - - - - - I i - I i * - OCH3 oet i d ’l l * »: • II i XT r - Figure 5. Formation pathways of arylglycerol via aromatic ring cleavage products from 0 0 4 models by P. chrysosporium and C. versicolor. *: 1: C. -- * In addition , we found that guaiacoxy ethanol is formed in considerable amounts from 4 ethoxy 3 methoxyphenylglycerol 0 guaiacyl ether (I) in the ligninolytic culture of P chrysospor ium (18). The formation of this compound^ from 4 ethoxy 3 meth oxyphenylglycerol 0 guaiacyl ether ( I ) was found by Enoki et al. ( 5). They proposed that the com pound is probably formed via retroaldol reaction of y aldehydic 0 0 4 dimers (Fig. 1 , pathway B). However , no such aldehyde derivative has been detected in the culture of P chrysosporium . We ^ (V) is not formed propose that the guaiacoxyethanol via retroaldol reaction of the y aldehydic 0 0 4 dimer (Fig. 1, pathway B). Because the guaiacoxy ethanol formed from 4 ethoxy 3 methoxyphenylglyc erol fl ’®0 guaiacyl ether (1 0 180) by ligninolytic culture of P. chrysosporium contained no 18O at all (Fig. 6). If the mechanism (Fig. 1 , pathway B) is true , the ethereal 180 must be retained in the product , guaiacoxyethanol ( V ). - --_ - -- - -- -- - -- »% ll « 11 - - -- - -- -...-- . 301 I JOI 11*11 - - -- - --- - -* - - - - -- - • v » - . Jin > » - . * * CJio | fl | 3 M i l l l M, | t» * Figure 7. Degradation pathways of deuterated arylglycerol B aryl ether models by ligninase -- - IXlXi I XVIIk Figure 8. Degradation pathways of deuterated 6 1 models by ligninase - Figure 6. Formation of guaiacoxyethanol from 4 ethoxy 3 methoxyphenylglycerol 0 guai acyl ether by chrysosporium We further identified 4 ethoxy 3 methoxypheny 1 B deoxydiol ( 22) , and , tentatively , glycol ester of 4 ethoxy 3 methoxybenzoic acid ( 23) as degra dation products of 4 ethoxy 3 methoxyphenylglyc - - -- -- - -- - - -- - -- - - - The results obtained demonstrate that the D labels at Cu or CQ of the substrates were almost ts quantitatively retained in the products after the C Cp and ether bond cleavages as summarized in ^ I. The present evidence clearly shows that Table - - hydrogen abstraction is not involved in both the 119 - C C and ether bond cleavages , which is consistent with the in vivo system (11 ,12). DD IN (S ) < % ) - - ( VI a,8 2 D) - - DD in ( P ) < % ) 100 98 ( XIV - D) 93 - - 95 ( II a , B 2 D) - - 89 100 ( XIV D) ( XV - D) - 96 93 98 100 - 95 97 -- 33 94 - 72 a 98 B 93 ( II - -a , B 2D) a 98 B 93 - B -D ) a ( XVI - - - - ( XVIII D) ( XVII a D ) ( XVIII D) ( XVII ) B 0 - # 0 a 98 - # # ( XIV D ) B 91 ( XVI a D) - B 80 total 89 ( Vll a , B 2 D) # # 98 78 ( XIII a ,0 2D) a 98 # Retention ( 1) B 80 ( XV -D) ( XIV D) a 98 - Arch. Biochem. Biophvs • 100: 140 149 (1963) 2. FUKUZUMI , T • AND SHIBAMOTO , T. J . JPn. Wood Res. Soc., 11: 248 252 (1965) 3. FUKUZUMI, T. , TAKATSUKA , H • AND MINAMIf K. Arch. Biochem. Biophys • 129: 396 409 (1969) 4. ISHIKAWA , H., AND OKI , T. J. JPn . Wood Res. Sor 12: 101 107 (1966) 5. ENOKI , A., GOLDSBY , G.P • AND GOLD , M.H. Arch. Microbiol • 125: 227 232 ( 1980) 6. ENOKI , A., GOLDSBY , G.P., KRISNANGKURA , K., AND GOLD , M.H. FEMS Microbiol. Lett., 10: 373 377 (1981) 7. ENOKI , A., GOLDSBY , G.P., AND GOLD , M.H. Arch. Microbiol., 139: 141 145 (1981) 8. TIEN , M., AND KIRK , T.K. Science , 221: 661 663 (1983) 9. TIEN , M., AND KIRK , T.K Proc. Natl. Acad . Sci. USA , 81: 2280 2284 (1984) 10. GOLD , M.H., KUWAHARA , M., CHIU , A.A., AND GLENN , J.K. Arch. Biochem. Biophys., 234: 353 362 (1984) 11. UMEZAWA , T• NAKATSUBO , F., AND HIGUCHI , T. Agric. Biol. Chem • » 47: 2677 2681 (1983) 12. UMEZAWA , T• » AND HIGUCHI , T. Wood Research , (71): 25 31 (1985) 13. UMEZAWA , T. , HIGUCHI , T., AND NAKATSUBO , F. Agric. Biol. Chem., 47: 2945 2948 (1983) 14. UMEZAWA , T., AND HIGUCHI , T. Agric. Biol. Chem. 100 - 0 98 - -D) a 98 ( XVIII -D) 96 Table I. Deuterium retention calculated from ( XVII a - . - degrees of deuteration (DD) of the substrates (S) and the products (P) - Alternatively , we have established that the heme enzyme model system catalyzes the C C bond cleavage of the lignin substructure models (6 1 , 6 0 4 , B 5) together with the quantitative D re tention patterns and 180 incorporation (83 %) from dioxygen into the cleaved product , phenylglycol , of the diarylpropanediol. On account of the one electron oxidizing role of high valent oxo ironporphyrin complex (Com pound I of peroxidase) formed in the presence of hydroperoxide , one electron might be transfered to the complex from the arylpropane substrate to form the cation radical intermediate , which undergoes the C C bond cleavages homolytically or heterolyt cally producing the carbon centered radical inter mediate. Consequently , the radical intermediate is readily attacked by molecular oxygen to form the dioxygen adduct and the corresponding hydroperox ic‘ ? , which are eventually converted to the hydrox yloted phenylglycol product. The reaction mecha nism proposed with our own enzyme model is in good agreement with the recent evidence for the aryl cation radical detected by ESR spectrometry in the ligninase system. Although the elucidation of the detailed reaction mechanism requires further in vestigation, the ligninase should be denoted as a type of peroxidase rather than H O rtquiring - - -- - - - - - - - - - - - - - ^ ^- oxygenase. However , it is not known that w! at enzyme medi ates the formation of arylglycerol via the cyclic carbonate and formate of arylglycerol which con tain Cj fragments from 6 etherated aromatic rings. Further investigations are in progress in our laboratory. - - - REFERENCES 1. ISHIKAWA , H • # SCHUBERT , W.J • » AND NORD , F.F. 120 # - - - - 48: 1917 1921 (1984) 15. UMEZAWA , T., AND HIGUCHI , T. FEMS Microbiol Lett., 26: 123 126 (1985) 16. UMEZAWA , T., AND HIGUCHI , T. FEBS Lett., 182: . - - 257 259 (1985) 17. KAWAI , S., UMEZAWA , T., AND HIGUCHI , T. App. Environ. Microbiol., Manuscript submitted 18. UMEZAWA , T., AND HIGUCHI , T. Unpublished data 19. HAMMEL , K .E., TIEN , M . , KALYANARAMAN , B., AND KIRK , T.K. J. Biol. Chem., in press 20. HABE , T., SHIMADA , M., OKAMOTO , T., PANJPAN , B• • AND HIGUCHI , T. Chem. Comm., Manuscript submitted 21. SCHOEMAKER , H.E. , HARVEY , P.J., BOWEN , R.M • # AND PALMER , J .M. FEBS Lett., 183: 7 12 (1985) - 22. KAWAI , S., UMEZAWA , T., AND HIGUCHI , T. Agric. Biol. Chem., in press 23. KAWAI , S., UMEZAWA , T., AND HIGUCHI , T. Unpublished data 24. HABE , T., SHIMADA , M., UMEZAWA , T., AND HIGUCHI # T. Agric. Biol. Chem., in press 25. SHIMADA , M., HABE , T., UMEZAWA , T. , TGUCHI , T. , AND OKAMOTO , T. Biochem . Biophys. Res. Comm., 122: 1247 1252 (1984) 26. HABE.T., SHIMADA , M., AND HIGUCHI , T. Mokuzai Gakkaishi , 31: 54 55 (1985) - - Figure 2 shows that the decrease In the electrophoretic mobility is directly related to a 3 .ransfer of H C PAM from the MCC to the coarse fiber fraction , the reason for this transfer being that the - -- adsorption is slower onto the coarse fiber fraction (slow penetration of the polymer into the porous cell wall of the fibers) than onto the MCC fraction. The faster rate of adsorption onto the MCC fraction is probably due to the smaller size of the substrate and correspondingly smaller diffusion distances into this substrate. T CT> cn E 7 T FIBRE CONC * 2 g / l MICROC CELL CONC * 100 mg / I PAM I ADD UJ CJ O •2 6 o o cc o 5 2 L o u A t • A 05 • if ) > or 4 mg / I o 3 o CL a: o) 2 if a < 2 *A 1 < CL 1 j 1 5 10 15 . > 20 TIME AFTER ADDITION ( min ) «• i• * Figure 2. -cellulose. fy 3 H C PAM adsorption onto microcrystalline -C-PAM added to a * suspension containing 2 g/ l bleached softwood kraft fibers and 100 mg/1 .J ralcrocrysta 11 ine cellulose. Same r • •• •j experiment as in Fig. 1. I *r These experiments are further substantiated by data showing different adsorption kinetics onto the fiber * fraction and onto the MCC fraction, and by experiments with non porous fibers (nylon) where these transient surface potential effects and polymer - transfer effects are absent. REFERENCES . STRA2D1NS, E., Tappl 55:1691 (1972) 1 STRAZD1 NS, E., Tappl 57:76 (1974) 3. L1 ND8TROM , T. and SOREMARX , Ch., Colloid Interiace Sc 1. 55:305 (1976) 22 »* CELLULOSE SUSPENSIONS AND POLYELECTROLYTES - S°ME RESULTS - In order to follow the adsorption of C PAM ont KINETIC ASPECTS he cellulose substrates, a series of cationic polyacrylamides (copolymers of acrylamide and N ,N TOM LINDSTP M diethylaminoetylacrylate quaternlzed with di - DEPARTMENT F PArER TECHNOLOGY methylsulphate; courtesy of Allied Colloios , U.K . > SWEDISH FOREST PRODUCTS RESEARCH LABORATORY (STFI) were trltlated by means of 3H 2 (3H C PAM). In a typical experiment , the coarse fiber fraction of an unbeaten bleached softwood kraft pulp was dlsperx « d ° P.0. BOX 5604 — S 114 86 STOCKHOLM , SWEDEN -- at a concentration of 2 g /1 in a Britt Dynamic . Drainage Jar (BDDJ) equipped with a 100 mesh wire KEYWORDS; Adsorption , Radioactive tracers , Electrophoresis Microcrystalline cellulose , MCC ( model substance for fines), was then added to a concentration of 100 reg/1. Each experiment started with the addition of a -- given amount of 3H C PAM. Samples of the MCC were withdrawn from the BDDJ and the electrophoretic mobility was determined together with the araounE of adsorbed 3H C PAM. In order to determine the amount of adsorbed -H-C-PAM onto the MCC , the samples were filtered on a filterpaper on a Buchner funnel Immediately after separation from the BT * J. Figure 1 shows the electrophoretic mobility of the -- MCC at different times after addition of the 3 H C PAM to the fiber and MCC suspension In the BDDJ. The high INTRODUCTION In the practical application of various retention aids such as high molecular weight cationic polyacrylamides in the papermaking process , the positive initial electrophoretic mobility followed by a decrease with time is typical . e contact time between the polymeric additive and the pulp suspension is of the order of seconds. The o > kinetics of polyelectrolyte adsorption onto the pulp in and the flocculation of the 9tock are therefore of decisive Importance. Transient surface potentials , - l.e. chafges in the z potential with time after the *1 addition of a charged polymer to a cellulose pulp suspension , were apparently first recorded (by means of microelectrophoresis) by Strazdlns (1 ,2). Later , studies in this laboratory (3) confirmed these observations when a cationic polyacrylamide - (C PAM) was added to a fiber suspension. The unexpected observation in these studies was that the electrophoretic mobility of the fines fraction decreases from a positive value to a negative value > CD O x o ID Qd O X CL O Qd O ID ID with time Instead of increasing from a negative to a - positive value. The rate of adsorption of C PAM onto the coarse fiber fraction was found to be much slower than onto the fibril (crlll or fines) fraction (3), - and It was suggested that the C PAM initially adsorbs to the fines and recharges them. As the coarse fiber TIME AFTER ADDITION ( mirv ) Figure l. The electrophoretic mobility of raicrocrystalline cellulose particles - (cone. 100 mg / 1) separated from a material starts to adsorb the polymer , the fines bleached softwood kraft fiber fraction desorb the polymer and the electrophoretic mobility of the fines decreases at a rate corresponding to the (fiber cone. 2 g / i) at different times after addition of }H C PAM (PAM 1). rate of adsorption of the polymer onto the coarse Various levels of addition of 3H C PAM. fiber material. The object of the present - -- -- Investigation was to substantiate this hypothesis with direct experimental evidence for such a transter mechanism. 121 Figure 2 shows that the decrease In the electrophoretic mobility is directly related to a transfer of 3H C PAM from the MCC to the coarse fiber -- fraction , the reason for this transfer being that the adsorption is slower onto the coarse fiber fraction (slow penetration of the polymer into the porous cell wall of the fibers) than onto the MCC fraction. The faster rate of adsorption onto the MCC fraction is probably due to the smaller size of the substrate and correspondingly smaller diffusion distances into this substrate. CT> CT> E UJ o if) > a: o o or o Z o o a. cr o) if a < z < CL TIME AFTER ADDITION ( min ) «• •* • . jH-C-PAM adsorption onto microcrystalline cellulose. 3H-C PAM added to a Figure 2 . - * suspension containing 2 g/1 bleached softwood kraft fibers and 100 mg /1 ~J . Same raicrocry6 ta 11 lne cellulose * .« r i . experiment as in Fig. 1 .r % / These experiments are further substantiated by data showing different adsorption kinetics onto the fiber fraction and onto the MCC fraction , and by experiments with non porous fibers (nylon) where - these transient surface potential effects and polymer transfer effects are absent. REFERENCES . STRAZD 1 NS, E., Tappl 55: 1691 (1972) 1 STRAZDINS , E., Tappl 57:7b (1974) 3. LINDSTROM , T. and SOREMARK , Ch., Colloid Interlace Scl. 55:305 (1976) 122 »' * v *« »w . %• » ( * - ANALYSIS OF POLYPHENOL DERIVED AROMATICS IN 10D CARL P GARLAND * , FREDERICK C JAMESt , PETER J NELSON * and ADRIAN F A WALLIS* *CSIRO DIVISION OF CHEMICAL AND WOOD TECHNOLOGY , PRIVATE BAG 10, CLAYTON , VICTORIA 3168, AUSTRALIA tFACULTY OF APPLIED SCIENCE , ROYAL MELBOURNE INSTITUTE OF TECHNOLOGY , PO BOX 2476V , MELBOURNE , VICTORIA 3001, AUSTRALIA sugar diesters of hexahydroxydipftenic acid ( la ) (ellagitannins); condensed tannins , which are proanthocyanidin polymers possessing units of structure Ha ; ellagic acid ( Ilia ) and stilbenes ( 5 ). Existing methods for the determination of these substances in wood rely on examination of We present new approaches to the extracts. analysis of wood polyp enols which involve direct degradation of wood either by oxidation with permanganate or by treatment with alkali. COOR2 ABSTRACT Difficulties encountered in the estimation of lignin and polyphenol contents of certain woods are outlined. Methods for the determination of polyphenols in wood involving degradation of wood and measurement of the resulting products by gas chromatography (GC) are discussed , A four step procedure , based on permanganate oxidation of ethylated wood , allowed the estimation of pro COOR 2 . R .O OR OR i * OR i OR i OF Ri R2 I o H sugar b C2H5 CH 3 - - R « H antliocyar ins and related polyphenols as the methyl etr xybenzoates IVa c. Two approaches to the deterr nation of ellagitannins in wood , by alkaline treatment of ethylated wood to give the diphenic acid derivative lb , and by alkaline decarboxyla * ion of wood to the hexahydroxv biphenyl (HHBP) V , were unsuccessful. . - R 8 C 2" H 5 - - INTRODUCTION Klason lignin analyses of Eucalyptus woods which contain polyphenols can give anomalously high values because the polyphenols are included in the acid insoluble Klason lignin residue , In certain Eucalyptus woods , the polyphenols cannot be extracted with neutral solvents , and boiling aqueous sodium hydroxide is often required for their complete removal (1). Under these alkaline conditions, appreciable amounts of lignin and hemicelluloses may become solubilized , particularly from the heartwoods. Determination of Klason lignins corrected for polyphenols may be carried out by a method based on the methoxyl contents of Klason lignin residues from both unextracted and alkali extracted woods ( 2 , 3). An assumption in the method is that the lignin in both the unextracted and alkali extracted woods has the same methoxyl content. However , this assumption must be treated with caution , as lignin extracted from E. regnans wood has been shown to be richer in guaiacyl relative to syringyl groups than the original lignin (4 ). Methods for detection and direct estimation of polyphenols in wood were R * H .2 5 R * C H COOCH 3 EZ - - - RI Ri «2 OC2H5 a H H b OC2H5 H C OC2H5 OC2H5 EXPERIMENTAL Wood samples were Wiley milled to pass through a 1 mm sieve. The woodmeals were extracted with boiling water and boiling 0.1 M sodium hydroxide according to the Appita standard methods P 4m 61 and P 5m 68 , respectively. Cold alkali extractions of woodmeals were carried out with 0 * 1M sodium hydroxide at 20°C for 24 h. Additional samples were Soxhlet extracted for 18 h periods sequentially with acetone and methanol. - - therefore sought. Polyphenolic extractives in eucalypt woods occur typically as hydrolysable tannins , chiefly Ethylation of woodmeal Woodmea 1 ( 1.0 g ) was suspended in a mixture of 123 - - 30 mL methanol dimethoxyethane water (21:21:18 , v/v/v) adjusted to pH 11.0 with 2M sodium •droxide , and 2 mL diethylsulphate was added , a mixture was kept under nitrogen at 20°C for 24 h and the pH was maintained at 11.0 by periodic addition of 2M sodium hydroxide with the aid of an automatic titrimeter. After acidific ation with 1M hydrochloric acid , the mixture was kept at 80°C for 30 min. The mixture was cooled , filtered and the ethylated woodmeal was washed with cold water and dried. - pH 2 and extracted with 50? acetone chloroform ( 3 x 30 mL). The extracts were dried and the residue after evaporation of the solvent was methylated with diazomethane and examined by GC after addition of pyromellitic acid tetramethyl ester as the internal standard. - Permanganate oxidation of ethylated wood A suspension of ethylated woodmeal (200 mg ) in t butanol (10 mL ), 2M sodium hydroxide (10 mL), 0.03M potassium permanganate ( 20 mL) and 0.12M sodium periodate (50 mL) was shaken and then heated under reflux for 6 h. Additional solid - potassium permanganate was added periodically so that the mixture remained purple in colour. After cooling , ethanol (10 mL) was added and the mixture was left to stand for 18 h. The treated woodmeal was collected by filtration and washed with 1% sodium carbonate solution. The combined filtrate ! and washings were acidified to pH 4.0, concentrated to ca. 30 mL in a rotary evaporator , I ^nd after addition of sodium carbonate (900 mg ) 30% hydrogen peroxide (5 ml), kept at 50°C for 10 min. The solution was cooled , and manganese dioxide (100 mg ) was added , After the evolution of gas ceased , the mixture was filtered and the residue washed with 1% sodium carbonate. The filtrate was acidified to pH 2 with 5M sulphuric acid , extracted with 50% acetone |chloroform ( 3 x 50 mL) and dried. The product was obtained after evaporation of the solvent. - Methylation and GC analysis A large excess of diazomethane in diethyl ether was added to a solution of the oxidized product in methanol (2 mL) and the mixture was kept at 4°C for 18 h. After evaporation of the Preparation of the HHBP (V) A suspension of ellagic acid (1.0 g ) in 4 M sodium hydroxide ( 10 mL) was sealed under nitrogen in a 20 mL steel autoclave and was kept at 170°C for 2 h in a rocking air bath , After cooling , the contents of the autoclave were immediately acidified to pH 2 with 5M hydrochlor IC acid and cooled in an ice bath. The precip itate which formed was filtered and washed with cold distilled water. The dried material (405 mg) was dissolved in hot water , purified with charcoal , and the white needles of V which were obtained on cooling had a mp > 350°C. - Estimation of ellagic acid as the HHBP (V) - Ellagic acid (12 50 mg) and 0.5M potassium hydroxide (5 mL) were sealed under nitrogen in 15 mL glass vials , and the vials were kept at 105°C for periods of 18 96 h. After opening the - vials , the contents were immediately acidified to pH 4 , transferred to 100 mL flasks and freeze - dried. Methanol ( 5 ml ) containing disyringyl methane (6 mg ) as internal standard , was added and the mixture shaken. An aliquot (ca. 2 mL) was evaporated under nitrogen and the residue was silylated with N ,0 bis( trimethylsilyl ) trlf 1 uoro acetar.ide (BSTFA)(100 uL) at 100°C for 24 h. Excess BSTFA was removed under nitrogen , and dichoromethane (1 mL) was added prior to GC analysis on a SE30 bonded phase capillary column , with a column temperature of 230°C. Additional experiments were carried out with ellagic acid in the presence of woodmeals (500 mg ) .tnd alkali extracts from woodmeals , as well as with woodmeals themselves. - - - solvent , dichloromethane (1 mL) containing pyromellitic acid tetramethyl ester (6.0 mg ) as internal standard was added. The GC analysis was carried out with a SE30 bonded phase vitre J S silica capillary column (12 m x 0.22 mm ID) (SdE Scientific , Melbourne ) in the splitter mode , an 1 detection was by flame ionization. Alkaline treatment of ethylated wood Samples of ethylated woodmeal ( 200 mg ) were hwuted under reflux with 0.1M sodium hydroxide ( 20 mL) for 1 h. The woodmeal was collected by filtration and washed with warm water. The combined filtrate and washings were acidified to 124 - RESULTS A ID DISCUSSION Permanganate oxidation of wood % - Oxidative methods for the estimation of poly phenol derived aromatics in wood were explored. The polyphenol derived products can be distinguished from 1 ignin derived aromatics by the absence of methoxyl substituents on the aromatic rings of che former. An exception is ’ the h/droxyphenyl moiety , which may occur in both lignin and polyphenolic extractives. Initial experiments showed that alkaline nitrobenzene and alkaline cupric oxide oxidation at 170°C were not appropriate methods for the - ^- - - - analysis of polyphenols in wood , as protocatech ualdehyde and protocatechuic acid , typical of the expected oxidation products , were not stable Application of under the reaction conditions. •rhese oxidants to ethylated polyphenols was also not a useful approach , because tetraethyleatechin (lib), a model for ethylated proanthocyanidins in wood , did not yield products identifiable by GC. (i ) (ii) (C 2 H 5)2 S04 KMn04 NaI04 - ^ (iii) H 2O2 (IV ) CH 2 N 2 Permanganate oxidation procedure The adopted method (Scheme 1) is a modification of the permanganate oxidation procedure which has been used for lignin structural studies (6 , 7). The initial step is the ethylation of the phenolic hydroxyl groups in the wood samples with Sequential oxidation diethylsulphate at pH 11. of the ethylated wood with alkaline potassium sodium periodate , and hydrogen permanganate peroxide , gave substituted aromatic acids , which after treatment with diazomethane were determined The products were as their methyl esters by GC. identified by comparison with authentic samples by GC mass spectrometry. Oxidation of tetraethyleatechin ( lib) by the above procedure gave the methyl benzoate IVb in When the hydrogen peroxide step was 86% yield. omitted , the yield of IVb was reduced to 55%. Compound IVb originates from the C ring of the ethylated catechin , and no product deriving from Application of the the A ring was identified , oxidation to tetraethylellagic acid (Illb) gave no product identified by GC. When various eucalypt woodmeals were subjected to the oxidation procedure , a series of Of substituted methyl benzoates were obtained , the woodmeals from the four eucalypt species in Table 1 , E. regnans gave no diethoxybenzoate IVb , whereas the other species yielded 1 3% on oxidat ion. E. regnans is representative of a pale brown heartwood species and the other three species form part of the red coloured group of species ( 5). The latter group are known to contain proanthocyanidins (5 ,8 ,9), and compound IVb may derived from the C ring of units of The origin of ethoxybenzoate IVa structure Ila. could be lignin , proanthocyanidins , or hydroxy stilbenes. Compound IVc , the gallic acid derivative , may either originate from gallotannins or proanthocyanidins. The components which give rise to ethoxybenzo •ites IVa and IVb are only extracted to a limited extent with boiling water or acetone methanol , - - - - - - - - - - - - - . - Wood Sample ETHOXY AROMATIC ACID METHYL ESTERS WOOD Scheme 1 and require an alkaline extraction for their removal. however , the substance which yiel ; the gallic acid derivative IVc are removed w: h boiling water or organic solvents , The lat er substances are more likely to be gallotannin.. or gallic acid itself rather thin polymers of the delphinidin type , which would not be expected to be removed with neutral solvents. % Yield (w/w) of Benzoic Acid IVa E. regnans heartwood E. tetrodonta Derivative IVc IVb tr. 0.1 heartwood E. diversicolor heartwood boiling water extracted 0.1 1.1 0.3 C. 3 C .5 0.6 acetone methanol extracted cold alkali extracted boiling alkali extracted 0.3 2.2 2.0 2.0 0.2 0.2 0.2 0.2 0.1 1.2 0.8 0.8 0.2 0.1 tr. 0.1 0.2 0.1 tr. 2.7 0.9 - E. diversicolor t sapwood boiling water extracted acetone methanol ex racted cold alkali extracted belling alkali extracted E. marginata heartwood cold alkali extracted boiling alkali extracted E. marginata sapwood boiling water extracted - Table 1 tr. 0.1 0.1 tr. tr. tr . 0.7 0.2 0.2 1.5 0.4 1.2 0.8 Permanganate Oxidation of Woodmeals Alkaline degradation of polyphenols 1 Alkaline hydrolysis of ethylated wood Estimation of the aromatic groups in the hydrolysable tannins was attempted by a method in which the ethylated tannins were hydrolysed to their parent acids and measured as the methyl Thus the diphenic acid derivative esters by GC. lb and the methyl triethylga 1 late IVc would be the expected products from ethylated ellagi tannins and ga 1 lotannins , respectively. Sequential treatment of ethylated eucalypt wood samples with boiling 0.1M sodium hydroxide and diazomethane afforded the trlethoxybenzoate IVc with smaller amounts of the diethoxybenzoate IVb (Table 2). No trace was found of the ellagitannin derived diphenic acid ester lb. The detection of compound IVb was unexpected , as esters of protocatechuic acid are not known structural features of lignin or polyphenols. - - 2 Alkaline treatment of ellagitannins in wood An attempt was made to estimate the polyphenol moieties in e 1 lagltannins as the hexahydroxybi phenyl (HHBP) V , based on the observation of Hemingway and Hillis ( 10) that ellagic acid - 125 (w/w% wood basis) IVb IVc E. diversicolor heartwood E. marginata sapwood E. marginata heartwood E. tetrodonta heartwood Table 2 10 HEMINGWAY , R W and HILLIS, W E. (6), 933 (1971). 11 HILLIS , W E , ROZSA , A N and LAU , L S. Chromatogr • • 109 , 172 (1975). % Yield Wood Sample 0.1 0.1 0.1 trace 0.3 0.6 0.1 0.4 Tappi 54 Alkaline Hydrolysis Products treated with 0.5M sodium hydroxide at 160°C gave the aecarboxylated product V. The present approach would allow the measurement of both ellagic acid and the aromatic groups in ellagi tannins, and would supplement the method of Hillis et al. (11) for estimation of free ellagic acid in wood. Reaction of ellagic acid with 0.5M potassium - hydroxide at 105°C for 48 h gave the HHBP (V ) (estimated by GC as the trimethylsilyl ether) in 76 % yield. However, when various eucalypt woods were digested with alkali at 105°C or 170°C , neither the HHBP (V) nor pyrogallol , which could arise from decarboxylation of gallic acid , were identified as products, Furthermore , when the decarboxylation reaction of ellagic acid was carried out in the presence of eucalypt woods or alkaline extracts of these woods, the yield of V . was reduced to ca. 5%. The eucalypt woods would je expected to contain ellagitannins , and the HHBP (V ) formed by hydrolysis/decarboxylation probably undergoes alkali catalysed condensation reactions with lignin extracted from the woods. The approach for analysis of ellagitannins was not pursued further. - - J . REFERENCES " Wood Extractives" , Chapter 1 HILLIS , W E. 2 , Acadmic Press , 1962. 2 COHEN , W E. Pamphlet No 62, Coun. Sci. 3 4 Ind. Research , Australia (1936). BLAND , D E and MENSHUN, M. Appita 25(2), 110 (1971). BLAND , D E and MENSHUN , M. Appita 23(6), r 427 (1970). HILLIS, W E. " Lucalypts for Wood * 5 6 7 9 126 Production " ed W E Hillis and A G Brown , Chapter 12, CSIRO/Academic Press , 1984. ERICKSON , M , LARSSC'N , S and MIKSCHE, G E. Acta Chem. Scand. 27, 127 ( 1973). GLASSER , W G , BARNETT , C A and SANO , Y. J. Appl. Poly. Sci: Appl. Poly. Symp. 3J7 , 441 (1983). MICHAEL , M and WHITE , D E. Aust. J. Appl. Sci. 6 , 359 (1955). HILLIS , W E and CARLE , A. Biochrm. J. 82 , 435 ( 1962). r • 9 J. d e a l s w i t h p r e o x 1d a T :e n o i u i l f e r e n t t y p e s o f pulp and an a l t e r n a t i v e me . hod t o r e g e n e r a t e nitrogcn diox lde. ' OXYGEN BLEACHING FOLLOWING PREOXIDATION OF WOOD P U L P S W I T H N / Q2 02 OLOF SAMUELSON CHALMERS UNIVERSITY OF TECHNOLOGY , DEPARTMENT OF ENGINEERING CHEMISTRY S- 4 1 2 9 6 G O T H E N B U R G , S W E D E N DIFFERENT Pit; PS ( l o w c r k e r PER SJOGREN ) Kraft pulps from softwood received in wet con d i t i o n have been used in most previous work . Re maining inorganic constituents which neutralize - - the nitric acid produced during the preoxidation can e x e r t a s e r i o u s e f f e c t on the r e s u l t s ( 3) . If - ABSTRACT Preoxidation of sulphate pulp from pine gave r i s e t o a l a r g e r i n c r e a s e i n s e l e c t i v i t y (v i sc o s i t y a t a given kappa number) a f t e r oxygen bleaching than that observed with birch sulphate p u l p . L a r g e r a m o u n t s o f C 0 -, a n d N , 0 w e r e p r o d u c e d from birch than from pine pulp. The production c o n t i n u e d l o n g a f t e r t h e a d d e d N0 ? w a s c o n s u m e d completely , indicating a massive regeneration of NO2 I n s u f f i c i e n t r e g e n e r a t i o n c a n , t h e r e f o r e , not explain the unfavourable results with birch . pulp. Experiments with pine pulp showed that addition of oxygen is not a prerequisite for a massive regeneration. Treatment of lignin with acid nitrate solution gave rise to large amounts of NO NO e v e n when n o o x y g e n was a d d e d . T h i s 2 s u g g e s t s t h a t NO c a n b e g e n e r a t e d i n c o n n e c t i o n with the recovery of spent liquors from the pro ^ - c e s s. KEYWORDS: Nitrogen dioxide , Nitric acid , Oxygen , Bleaching, Lignins , Dinitrogen oxide , Carbon dioxide. INTRODUCTION © process invented by the author and The PRENOx d e s c r i b e d i n s e v e r a l p a t e n t a p p l i c a t i o n s t o Mo och Domsjd AB and p u b l i c a t i o n s from Chalmers University of Technology will shortly be studied in a pilot plant built by Sunds Defibrator at the Oestrand kraft mill The process is based on a preoxidation of unbleached pulp in the presence of N and 0 followed by an alkaline treatment pref e r a b l y oxygen bleaching. A main f e a t u r e i s t h a t . 02 ^ the conditions during the preoxidation are such t h a t NO I S r e g e n e r a t e d from p r o d u c e d a n d a d d e d n i t r a t e and u t i l i z e d repeatedly ( 1) The preoxidation results in a protection of the ^ . - carbohydrates reflected in a suppressed dcpolv roerization rate during the oxygen bleaching. Under roost c o n d i t i o n s the d e l i g n i f i c a t i o n a f t e r the oxygen bleaching is improved ( 2 ) . Both factors contribute to an enhanced selectivity , defined as viscosity a t a given kappa number This report . not otherwise stated the pulps used in our labora tory were washed carefully with demineralized water subjected to distillation in quartz glass e q u i p m e n t . By t h i s p r o c e d u r e t h e s e r i o u s e f f e c t of trace metals (mainly copper) present in tap water and d i s t i l l e d water was eliminated . During the preoxidation or before this stage metal ions present in the pulp are dissolved in produced or added n i t r i c acid. In laboratory ex - periments it is tedious to recirculate the liquors in a manner simulating the conditions in a plant with continuous preoxidation , oxygen bleaching and recovery of the spent liquors. To avoid the d i f f i c u l t i e s we have in the present work used pulps soaked with 0.1 M hydrochloric acid a t room temperature for 30 min before washing with the purified water. Most previous reports are based on experiments with industrial kraft pulps of high viscosity. Even in the same mill the viscosity and kappa number c a n v a r y from t i m e t o t i m e. A p u l p o f higher kappa number and a lower viscosity than most pulps used in our previous wash , was there fore studied . - T h e p u l p w a s i m p r e g n a t e d w i t h 0 . 3 m o l a l N a N O -. i n 0 . 1 m o l a l H N O, b e f o r e t h e p r e o x i d a t i o n ( 4 ) . I n a d d i t i o n a programmed t e m p e r a t u r e ( 3) and a p r o grammed introduction of oxygen (5) were used . - Under proper conditions a l l these precautions leal to an increased selectivity In the preoxidation 1 » NO , w a s i n t r o d u c e d i n t o t h e e v a c u a t e d r e a c t o r a t 5 2 C ( z e r o t i m e ) f o l l o w e d b v l i NO, a f t e r 3 min . Air , 300 ml , was introduced a f t e r a t o t a l t i m e o f 5 m i n . T h e t e m p e r a t u r e w a s r a i s e d t o 6 5°G during t h e period 7 17 min and 300 ml a i r added . ° - . After 30 min a i r was introduced to atmospheric pressure. The preoxidation was inter a l t e r 1" min rupted after a total time of 60 min. All treat ments referred to in this paragraph were carried o u t w i t h 75 g p u l p i n a 2-L i t r e r e a c t o r . The plots ot viscosity versus kappa number ( Fig 1 ) show that preoxidation at cither 15 or . 27 consistency resulted in a markedly improved selectivity after the oxygen bleaching The pre oxidized pulps were delignified to kappa number 9 . - b e f o r e t h e v i s c o s i t y d e c r e a s e d t o 9 5 0 dm 'Vkg , I n 127 in & '+ • 'L . the blank with acid-soaked pulp the viscosity dropped t o t h i s value at a kappa number of about 1 6 . A f t e r a n y g i v e n d u r a t i o n o f t h e o x y g e n b l e a c hing the kappa numbers were lowered markedly as a result of the preoxidation . The loss in viscosity during the preoxidation was counterbalanced by T h e e f f e c t s o f p r e o x i d a t i o n o f a n i r. d u s t r i i al birch sulphate pulp and of soaking are shown in Table I . The water- impregnated pulp was pre o x i d i z e d w i t h 2 l N O ? a t 6 5 ° C f o r 6 0 m i r. w i t h o addition to atmospheric pressure after 1 in and 30 min . In the experiments with unsoaked pulp - f ^ the the protection effect . Since an acid soaked pulp was used as reference the improved selectivity v i s c o s i t y dropped from 1238 t o 950 dm3 kg cannot be related to a removal of detrimental trace metals . d e c r e a s e d f r o m 1 7 . 5 t o 9 . 0 . I n t h e b l a r. l without preoxidation the same loss in v i s c o s i t y was ob t a i n e d a f t e r 3 0 m i n . T h e k a p p a n u m b e r w a s 11.5 . Hence , the preoxidation led to a markedly in* creased protection of the carbohydrates during the oxygen bleaching and to an improved selecti< vity . The same improvement in s e l e c t i v i t y and i 01 about the same protection effect were , however , o b t a i n e d by s o a k i n g with h y d r o c h l o r i c a c i d . Pre» oxidation of the soaked pulp had only a slight •* ; influence on the subsequent oxygen bleaching . 4' Evidently , the main effect of the preoxidation was a removal o f c a t a l y t i c a l 1y a c t i v e metal com , 3 pounds before the oxygen bleaching (Sec also •.7 Fig . 2) . ; 1200 1100 UP after 2 hours in the oxygen bleaching . The kappa number * - t i 1000 2 ce 5E - * ' * 900 10 IS 25 20 ss 90 .* « 40 0 KPTTO MJHBEJt 1. Fig. Intrinsic viscosity versus kappa number after oxygen bleaching of kraft pulp from soft( m a i n l y P i nus s y l v e s t r i s ) . The h i g h e s t wood kappa numbers and viscosities in each series refer to pulps before oxygen bleaching, x Preoxidation o Blank , no preoxidation at 15 and A 272 consistency A comparison with results obtained with other kraft pulps shows that a low viscosity of the unbleached pulp has a larger detrimental effect on . 4 the selectivity after oxygen bleaching than a high kappa number . 1a b 1 e I. kappa number Duration of the oxygen bleaching and ( interpolated values) at an i n t r i n- 3 s i c v i s c o s i t y of 950 dm /kg . rnus s 1 e n c y 1 Washing with Soaking w i t h 0 . 1 M H C1 4 1 d u r i n g p r e- d i s t i l l e d water oxidar 1 on 2 Time min Kappa number Timp 30 10 *7 * IPfTfl >0«0 * Fig. 2. Oxvgen bleaching of b i r c h p u l p ( Be t u 1 a verrucosa ) folloving preoxidation under various conditions. Pulp imoregn. with water: x 152; A 272 consistency min Kappa number Pulp impregn . w i t h 0 . 3 mo1a 1 NaNO 1i n 0 . 1 m o 1 a 1 " HNO O 1 5 ; A 2 7 2 c o n s i s t e n c y , o B l a n k , n o p r e- 11.5 100 9.0 oxidation 120 9.0 110 8.5 110 9.0 100 8.5 a. The soaking with a c i d f o r 3 0 m i n a t 2 0 °C d e - creased the ash content from 0.73 to 0.162; Cu f r o m 3 t o 1 , P e f r o m 2 0 t o 1 2 a n d Hn f r o m 9 0 t o 4 mg per kg pulp . ^ In attempts to improve the e f f e c t o f the preoxidation , only the acid -soaked pulp was used . In two series of experiments with pulp impregnated w i t h a c i d n i t r .i t e s o l u t i o n i n c l u d e d i n F i g . 2 t h e conditions were the same as those used with kraft pulp from softwood w i t h the exception that the f l al temperature during the preoxidation was 128 t m increased from 65 to 72 C. These conditions led to a severe loss in viscosity during the preoxida tion , a markedly improved protection during the oxygen bleaching and an improved de 1 ign 1 fication after the oxygen bleaching. The net result was a significant ly improved selectivity for pulps of low kappa number. Under otherwise unchanged conditions a de creased final temperature to 65°C led to higher viscosities after the preoxidat . on and an improved selectivity for pulps of comparative ly high kappa number (Fig. 3). For pulps of low kapna number the decreased temperature had no significant effect on the selectivity . An experiment in which nitro gen was added instead of air showed that the selectivity was virtually unchanged provided that the addition of NO was increased from 2 to 3 ® . The results arc consistent with the observation (discussed below) that nitrogen dioxide can be generated from nitrate ions even when no oxygen is added. A comparison between the results with birch pulps and those with kraft pulps from soft wood shows that under applied conditions the pre oxidation has a much larger effect on the selecti vity with softwood than with birch pulps. ° - - nitric acid an improved selectivity can be achieved at medium consistency (7). Figs. 4 a 5 show that with kraft pulp from softwood a de creased consistency from 2 “ to 15’« led to an in creased production of both N 70 and C07. I ndepen dent of the consistency and the type of un bleached pulp the production continued long a ter the period of a few minutes when the added n i t r o gen dioxide was consumed virtually completely. The continued production is die to an extensive regencratio n of NO ,. * - - UJ Q o 2 UJ o ( ^ - 1200 0 I tr 2 5 » ° 90 60 90 120 P r o d u c t i o n o f N ,0 (k g p e r 1000 k g p u l p ) d u r i n g p r e o x i d a t i o n a t 68 C with 27. N0 a n d 0 o f ^ pulps impregnated with 0.3 molal NaNO in 0.1 ° 0 A 8 30 F i g. 4. o 1100 120 TIME,mm molai HN 5 - 03. ^ ^ . K r a f t p u l p P i n u s s y l v e s t r i s , k a p p a n u m b e r 38.7 Birch sulphate, Be t u 1 a verrucosa , kappa number 23.3 S u l p h i t e p u l p , P i c e a a b l e s ( K a r s t.) number 17.5 kappa u 2 1000 I 900 s IS 10 UVTP MUMBLR P i g. 3 . Oxygen bleaching of birch pulp following u n d e r v a r i o u s c o n d i t i o n s. A d d i t i o n o f a i r : x 1 5Z ; A 2 7 Z c o n s i s t e n c y A d d i t i o n o f N ,: D 1 5Z c o n s i s t e n c y ( 3Z NO ,) preoxidation FORMATION OF N ?O AND co, P r o d u c t i o n o f C O , ( k g p e r 1000 k g p u l p ) d u r i n g p r e o x i d a t i o n s r e f e r r e d t o i n F i g . 4. Larger amounts of N ?0 and C07 were produced trom sulphite pulp from spruce and a sulphate pulp from birch than from a kraft pulp from Different pulps (Coworker URBAN 0JTF.G) Dinitroge n oxide and carbon dioxide arc p r o ducctl in lignin reactions during preoxidatio n of kraft pulp at high consistenc y (6). Recent in F i g . 5. - vestigation s show that for pulps impregnated w i t h softwood . This is noteworthy since the effect ol the prcoxidatio n on the selectivit y after oxygen bleaching was much larger for the kraft pulp than for the other pulps . These and other results show that there is no generally valid rclarion - 129 II I a i ship between the oxidation of lignin to CO and the beneficial effects of the preoxidation on the delignification and protection of the carbo hydrates. For the birch pulp and the sulphite ulp the decreased consistency led to a decreased production of CO , , while the production of N ,0 was only slightly affected . The formation of N . 70 means that active nitro gen compounds are withdrawn from the regeneration cycle. The conversion of N07 to N O in these experiments was 5.51 or less calculated as per centage of the added NO -,. The volume of N ?0 CO , calculated at 68°C and atmospheric pressure was 0.5 m * per 1000 kg kraft pulp after preoxidation for 00 min at 151, consistency. These inert gases will dilute the gas phase. This can affect the chemical reactions in the reactor and the re quired addition of oxygen. Precautions with regani to the environment may also be justified . ^ - - 4 ^ - * ' - EFFECT OF OXYGEN (Coworker DENNIS RASMUSSON) In the experiments referred to in Figs. 4 and 5 nitrogen dioxide was evaporated into the evacuated reactor. Oxygen was then added so that atmospheric pressure was approached Experiments in which the initial oxygen concen tration was varied from 0 to 100* (of permanent 7s) by using pure helium , mixtures of oxygen and trogen and pure oxygen are referred to in , Tables II and III . In the experiments with oxygen containing gas , helium was added to atmospheric pressure to compensate for the consumed oxygen. In the absence of oxygen SUPERATMOSPHERIC pres sure was obtained . - - II . - ^- Influence of the initial O concentra t i o n o n t h e p r o d u c t i o n o f N O (k g p e r 1 0 0 0 k g p u l p ) d u r i n g t r e a t m e n t w i t h 2 % N 0 a t 6 5°C a n d ? 1 0 2 c o n s i s t e n c y o f k r a f t p u l p ( k a p p a n u m b e r 3 9 . 0) impregnated with 0.3 molal NaNO in 0.3 molal HNO Table ^ Time 1002 202 102 min ^ °2 °2 °2 °2 0.25 60 0.23 0.55 0.27 0.73 0.70 180 0.62 1.09 1.00 1.30 1.19 1 200 2.58 3. 3 2 3.90 3.45 T a b l e I I I. F o r m a t i o n o f C0 ( k g p e r 1 0 0 0 k g p u l p) i n t h e e x p e r i m e n t s r e f e r r e d t o i n T a b l e I I. Ti me 1002 20 % 1 0% 0% mIn °2 °2 °2 °2 20 0 . 93 0.83 0.91 60 180 2.51 A.1 5 2.05 3.26 1.05 2.61 4.13 3.59 1200 9.01 8.92 10.0 8.10 2.21 Independent of the composition of the gas phase the reactions proceeded over a very long period of time. The results indicate that the autocatalytic regeneration of nitrogen dioxide from nitric acid was very extensive both in the experiments with and without oxygen in the gas introduced into the reactor. The initiation of the regeneration is promoted by oxygen and i s one reaction which favours the formation of both N ,0 and CO ,. One reaction in the group which tends to suppress their formation is the c o n v e r s i o n of NO , - _ 03. to HN . GENERATION OF NO , (Coworker LARS ANDERSSON) N0? is produced during heating of dilute HNO with lignin in the presence of oxygen. More than 60 % of the free HNO was under favourable condi tions present as NO , ( including N , ) when in acid 04 nitrate solution was treated with lignin for 20 min at 56°C (8). Only a minor proportion of NO was produced . N0-, gave r i s e to nitro groups in the lignin. For this reason the yield of NO , decreased ^ - ^ on prolonged treatment . 0.26 Flic results show that very large amounts of N 0 and CO were produced even when no oxygen was 2 fur ent in the added gas. The highest production ol both N ,0 and C07 occurred when the gas con ned l o t oxygen. The lowest production of N ,0, h is a reduction product , was obtained with pure oxygen . The oxidation of lignin to CO , was somewhat higher w i t h pure oxygen than when pure - - ISO ^ ^ 02 20 helium was added . The results suggest that re actions responsible for the formation of N ^ O and C07 as well as competing reactions are favoured by oxygen . TIME mm F i g. 6. T r e a t m e n t o! I n d u l i n A T ( 1 8 . 4 g ) w i t h 27.6 g of 0.85 molal NuNO in 1.05 molal HNO in a 5 0 0 m l r e a c t o r a t 5 6°C . x 0 . 5 2 N O ,; o N o N O 2 ^ ^ Experiments with adiition of nitrogen instead of oxygen showed that a large amount of NO and an appreciable amount of NO., were produced already after a few minutes ( fig . 6) . The shape of the curves and the striking effect of a very small addition of NO, show that the process is autocatalyti c. After 20 min the molar concentratio n of NO plus NO , was approximatel y the same as in com parable experiments with oxygen addition. On prolonged treatment this concentration was much higher than in experiments with oxygen . This is explained by a less extensive nitration of the lignin reflected in lower nitrogen contents after 120 min (0.38 and 0.32 I) compared to 1.23 and 1.13 % when oxygen was added. When oxygen was added a decreased lignin addition by 50 % led to an increased maximum concentration of NO NO -, (8) while the opposite effect was obtained when nitrogen was added (not shown 1. It is evident that , like N © , oxygen pro 2 motes the initiation of the reaction between nitric acid and lignin. Reactions which suppress the yield of NO N07 , such as nitration and formation of nitric acid are , however , also favoured by oxygen. This suggests that under con ditions which favour the initiation (e.g . high temperature , presence of NO ) an increased yield of NO NO -, should by expected when oxygen is omitted . This was confirmed in experiments at 75 C under otherwise unchanged conditions. The reproducibil ity was , however , bad and the results are not shown . All results mentioned above were confirmed in a study with a continuous reactor (Fig . 7) which will be reported elsewhere (Samuelson and Oj teg). It can be mentioned that under favourable conditions (75°C no addition of 0, and effective removal of the produced gas) approximatel y 80 % of the added nitric acid was accounted for as NO plus NO ,. The experiments showed that these nitric oxides can be produced from spent liquors from the process. When this technique is used the prcoxidation can be carried out under conditions which lead to a lower acid hydrolysis ( lower acidity and temperature) than those employed when the consumption of NO, is kept at a low level by an effective regeneration during the preoxidation. Compared at the same consumption of NO , and degree °f delignifica tion after the oxygen bleaching , the new technique gives rise to a higher pulp viscosi lV , yield and strength of produced paper than a Process without production of nitrogen oxides 'D \E \E 1" [Ff1 - Fig . 7. Reactor for continuous production of NO A . Inlet of lignin slurry from peristaltic pump B . Receiver for treated slurry . * . Inlet nitrogen. D . Outlet of gas . E . Hot w a t e r circulation. REFERENCES 1. Symposium on Wood and Pulping Cnemistry , Japanese Tappi , Tsukuba Science City ( 1983). - - ^ ° SAMUELSON , 0. Proceedings 1983 Intern . 2. ABRAHAMSSON , K . , LOWENDAHL , L. and SAMUELSON, 0. , Svensk Papperst 84 R 1 S 2 ( 1981). 3. SAMUELSON , 0. , Svensk Papperst 88 R9 b (1985). 4. SAMUELSON , 0. , and SJ0BERG , L A. , Svensk Papperst 87 R 30 ( 1984). 5. RASMUSSON , D. , and SAMUELSON. 0: To be pub - - 1 ished . 6. ABRAHAMSSON , K., and SAMUELSON , 0., Svensk Papperst 87 R 110 ( 1984). 7. BASTA , J., and SAMUELSON , 0. , Svensk Papperst 87 R 125 ( 1983). . ANDERSSON , L., and SAMUELSON. 0. , Svensk Papperst 87 R 1 54 ( 1 984). 8 ACKNOWLEDGE MENTS This work was sponsored bv the 1959 Ars Fond for Teknisk och Skoglig Forsknmg samt Utbildning and by Mo och Dornsjd AB. - from the spent liquors . 131 Investigation on Lignins and Lignin Polymer Models by FTiR Spectroscopy 0, Faix Federal Research Centre for Forestry and Forest Products Hamburg FRG In the last two decades i t has been often demonstrated that IR spectra of ' ignins reflect very well their compositon of basic phenylpropane . units Therforo ! R spectroscopy has been recommended for lignin classi fication studies The main obstacle for a more frequent use of this . established routine analysis in lignin chemistry is the interrelation . . units containing carbonyl groups and aromatic units of IR bands , e g with different grades of OMe - substitution may . cause response at the same wavelength Moreover there are no reliable numerical methods to evaluate lignin IR spectra The purpose of this study was therefore the . quantitative evaluation of lignin IR spectra including mathematical / »< statistical handling of the data . Lingin - like polymer models ' DHP ' s ) , MWL ' s , dioxane / HC 1 , and Willstatter lignins were investigated using . - - the FTIR technic p- coumaryl ( H ) , coniferyl ( G ) and sinapylalcohol - ( S ) ( separately and in mixtures ) , isoeugenol and pinoresinol were used for DHP synthese:. Continuous ( Zutropf , ZT ) and discontinuous ( Zu uf , ZL ) polymerisat n methods were applied For 30 DHP ' s peroxidase . d for 14 . L DHP ' s laccase was used to initiate the random polymerisation process . Most of the DHP ' s were fractionated according to their solubility or to their molecular size ( mol wt ) on a Sephadex LH 60 column . Thus lignin - like polymers came into existence having extremely different analytical data with regard to composition of basic units and oxida - . Those were appropriate subjects to test the efficiency of IR spectroscopy in lignin chemistry . Ligninsof more than 130 plant species were isolated by standard methods . Those species belong to 40 families including the so - called " primitive" dicotyledones and mono tion levels cotyledones . For a l l Dreparates the C 900 formula were calculated. Their IR spectra were base line corrected and normalized in a way that the absorption of the dominant band was equal to 1 evaluated by the base line technic . . After that spectra were Multiple linear regression analyse were carried out in such a way that each one of the experimental / analytical data was alternatingly con- sidered as dependent variable and 15 IR bands as independent variables . Equations of the type y = bQ +b ^* ••• bnxn were obtained, where y = predicted value for an analytical datum; b = constant ; b 1 • • •bn = appropriate = numerical values of x i • •• IR bands at different wavelengths The ability of the regression equa tion to predict the response y for a certain group of preparates and coefficients for n IR bands ; . xn ^ .. combinations of them ( e g laccase or / and peroxidase DHP ' s , MWL ' s or / and dioxande / HCl lignins ) was calculated by determining the multiple correla tion coefficient R and the standard deviation s of calculated and experi mentally found values . Results : - - Multiple linear regression analysis of IR spectroscopical and experi mental data has been proved an useful data handling method. For calcu - lations i t is recommendable to take into account as many IR informations as possible. In this way interactions of IR bands can be mathematically eliminated to some extent . 133 - For the DHP ' s i t has been demonstra ted, that mol * H, moH G , mol % S , OMe / C 900 ’ 0 / C 900 values can be calculated independe ntly from each other on the basis of IR spectra The R values for that kind of calcu - . lations were around 0.985 and subsequen tly the correspond ing s values . were low - The best way to estimate the number of OH groups by IR spectroscop y seems to be the evaluation of difference spectra recorded by substrac tion of spectra from acetylated and non acetylated lignin . - IR data of MWL ' s and dioxande / HCl lignins can be jointly evaluated. OMe / C 900 values of 36 preparates of these types has been predicted on the basis of IR spectra giving values of R = 0.998 and s 4 . - OMe / C 900 values of 120 Willstatter lignins has been predicted result ing in R = 0.956 and s 5. - IR spectroscop y is a good screening method for lignin classificat ion. With this method i t can be demonstra ted , that some of the dicotyledon e .. plants ( e g Brachylaen a hutchinsii Hutch ( Composita e ) ; Tectona grandis L ( Verbenace ae ) ) have guaiacyl lignins Many dicotyledon e species have lignins containing only a few percent of syringyl units demonstrat ing that boundaries are fluid between typical guaiacyl and guaiacyl syringyl / . classificat ion groups . *t » ', t >• * •» 134 . - - dioxide considerable c r e a s e d . A m m o n i a causes t h e w e l l k n o w n p l a s t i f i cation of wood without subs tan tia1 wood d e g r a d a t i o n. THE ACTION OF GAS: ~ U S C H E M I C A L S 0" STRLSTUR AL TIMBER By sulfur portions of the polyoses are hydrolyzed , but also cellulose and lignin are degraded to become partly soluble in alkaline solutions and hot water, respectively The loss of substance of GERD WEGENER a n d DIETRICH FENGEL . WOOD RESEARCH INSTITUT E , UNIVERSI TY O F MUNICH WINZERER STRASSE A 5 about 10 % leads D 8 0 0 0 MUNICH A 0 , F . R . GERMANY - to a strong decrease in s t r e n g t h , e s p e c i a l l y i n t h e case o f h i g h m o i s t u r e ABSTRAC T content o f w o o d . C h l o r i n e h a 3 t h e m o s t d e g r a d i n g e f f e c t o f a l l g a s e s a p p l i e d . N e a r l y half o f t h e w o o d d i s s o l v e d d u r i n g t h e e x t r a c t i o n s t e p s. In Though the resistance of wood against chemi this - cals has been used and proved since long in many fields of industry and craft, wood defects may occur a f t e r l o n g - t i m e a c t i o n o f a g g r e s s i v e a t m o s p h e r e s o n s t r u c t u r a l t i m b e r. C h e m i c a l , m i c r o scopical - - and mechanical investigations on spruce wood exposed to gaseous chemicals of various ag gressiveness revealed f e c t s. However, cannot be industry a different degradation general established halls were as very degradation ef oxidizing particularly lignir medium a t t a c k e d t o b e c o m e s o l u b l e t o m o r e t h a n 7 0 %. is Scanning and transmission electron microscopical observations reveal several changes in the cell - walls b.u t i n a l l cases t h e c o m p o u n d m i d d l e l a m e l 1 ae a n d t h u s cell t i s s u e s t r u c t u r e a re r e m a i n i n g ( F i g. - pattern the conditions in the . On the heterogeneous whole the results support the usefulness of wood as a b u i l d i n g m a t e r i a l i n a g g e s s i v e a t m o s p h e r e s. KEYWORDS: S p r u c e t i m b e r ( P i c e a a b i e s ( L. ) Karst. ) , Gaseous c h e m i c a l s , A n a l y t i c a l m e t h o d s. INTRODUC TION Defects of structural timber in industrial production and storage halls caused by the a ction of aggressive atmospheres for long periods gave occasion for studies on the influence of gaseous c h e m i c a l s o n s p r u c e w o o d. Analytical methods experiments with to standard halls f o r 1 r o o f b e a m s. developed during laboratory A exemplary gases were applied rods attached to the ceilings of y e a r a n d t o b o r e cores t a k e n from In a d d i t i o n t o t h e e f f e c t s o f a g g r e s s i v e g a s e s acting on wood the sorption behaviour with r e s p e c t to t h e s e g a s e s was o f i n t e r e s t. T h e r e f o r e of f o r m a 1 d e h y d e , a m m o n i a , s u l f u r dioxide a n d c h l o r i n e o n s o l i d s p r u c e w o o d s a m p l e s for 2 8 t o 3 3 6 d a y s a t t e m p e r a t u r e s o f 2 0 a n d A 0 C ° ! HCH0: 55 C ) w a s I n v e s t i g a t e d b y means o f c h e m l ° cal , action mlcroscoplcal ( Besold , F e n g e l ^ Sorption experiments RESULTS Effects o f h i g h l y c o n c e n t r a t e d g a s e s The F i g u r e 1 . Cross s e c t i o n o f a b o r e core t a k e n from a 70 year old beam exposed to a S O a t m o s p h e r e. S E M m i c r o g r a p h. and mechanical methods 1983 ; F e n g e l , Hardell 1983 ). T h e amounts a n d t h e c h a r a c t e r i z a t i o n o f t h e s o l u b l e s o& talned b y e x t r a c t i o n o f t h e g a s t r e a t e d wood w i t h water , e t h a n o l b e n z e n e a n d d i l u t e a l k a l i fcive i m p o r t a n t d a t a o n c h e m i c a l c h a n g e s , w h i c h - - ultimate ly i n f l u e n c e t h e s t r e n g t h p r o p e r t i e s. *fter t r e a t m e n t w i t h f o r m a l d e h y d e a m i n u t e d e g r a dation o f p o l y o s e s was found , w h i l e d u e to a cer lain n e t w o r k e f f e c t t h e b e n d i n g s t r e n g t h I n - the gas absorption was measured as a function of time at wood moisture contents ( u > of 0 %, 1 1 % and 20 % . The most significant result the maximum absorption of SO ^ is the Increase of at reduced moisture c o n t e n t. In c o n t r a s t , a m m o n i a a n d c h l o r i n e a r e much better absorbed at increasing moisture c o n t e n t. T h e m a x i m u m w e i g h t o f a b s o r b e d a m m o n i a a m o u n t s to a b o u t 7.7 % , r e l a t e d t o w o o d C l n i s a b s o r b e d u p t o 15.5 % a t u 20 % while only . = about 2 % are absorbed -- at u s 0 %. A v e r y f a s t s a t u r a t i o n i s r e a c h e d w i t h small a m o u n t s o f S0 n I A.3 % ) a t u 20 % while the maximum absorption i n t h e d r y w o o d m a k e s u p 1 3 %. 135 To determine the amounts of fixed gas the samples the actual were flushed with nitrogen for 12 h after having marginal regions of structural r e a c h e d s a t u r a t i o n. N e a r l y t h e w h o l e C l ( 9 0 1 0 0 %) i s f i x e d i r r e v e r s i b l y w h i l e a b o u t 4 0 5 0 % o f cleared up ^- - - into the better wood than gases in - take up of . Evidently the high a regions was of differe nt b y means o f EDXA . analysis - the larger m o l e c u l e s o f S0n a n d Cl , even u n d e r a b s o l u t e d r y c o n d i t i o n s. the the t i m b e r. T h i s sulfur in the earlywood s u r f a c e i s w a s h e d out ( left s i d e ) a n d t h e s u l f u r c o n c e n t r a t i o n d e c r e a s e s t o z e r o a f t e r f o u r a n n u a l r i n g s ( r i g h t s i d e ). is the three gases penetrate by to Figure 2 demonstrates the sulfur distribution of t h e o u t e r m o s t a n n u a l r i n g s o f a b o r e c o r e. There - . The small molecules are able to both layers of bore cores and S0? a n d o n l y 2 0 3 0 % o f NH ? r e m a i n in t h e w o o d . I f t h e actual a m o u n t s o f a b s o r b e d g a s e s are c o n s i d e r e d NH has the highest absorption values of ^ wood degradation is restricted ^ In p r i n c i p l e t h e d i f f u s i o n r a t e o f the presence of water is mainly in fluenced by - *7» i the solubility of the gas in water, possible reactions with cell wall components, by a n d b y t h e s w e l l i n g b e h a v i o u r o f t h e c e l l w a l l s. Characterization of standard rods and bore cores from industrial halls For c h a r a c t e r i z i n g a n a l y t i c a l l y structural timber exposed pheres standard rods and to the state of aggressive bore cores were subjec t e d t o t h e f o l l o w i n g i n v e s t i g a t i o n s: 1 - atmos . pH V a l u e o f t h e c o l d - w a t e r e x t r a c t 2. E x t r a c t i o n f o r 1 h w i t h b o i l i n g NaOH ( 1 % ) and water, respectively 3. GPC o f t h e e x t r a c t s i 4. GC o f c h l o r o f o r m s o l u b l e s o f w a t e r e x t r a c t s 5. E l e m e n t a n a l y s i s ( EDXA ) i n b o r e cores. F i g u r e 2. S u l f u r d i s t r i b u t i o n i n t h e o u t e r m o s t region of a bore core from a hall in w h i c h t h i o s u l f a t e i s p r o d u c e d. EDXA . T h o u g h t h e pH o f s a m p l e s from 7 h a l l s v a r i e d b e t w e e n 3 . 3 a n d 6 . 7 t h e pH v a l u e a l o n e i s no s i g n i Analytical ize The best indication for a weakening of structural lmber is the amounts of solubles extractable w i t h d i l u t e a l k a l i a n d w a t e r. W h i l e n o r m a l l y . The molecular weights of the soluble fragments d i f f e r in a w i d e r a n g e b e t w e e n a f e w h u n d r e d s and m o r e t h a n 20 ,000. T h e r e s u l t s car b e u s e d t o a r gue for a possible degradation patte - - bu t give no h i n t to t h e d e g r e e o f d e g r a d a t i o n. The s a m e i s true for products . the GC determination Though it was proved components 136 that the * are affected b y a c r •* * of degradation finical c e l l u a 11 ve a t m o s p h e r e s exposure results and ' methods are suitable to character wood samples with regard after a b o u t 1 0 % a n d 2 %, r e s p e c t i v e l y , o f s p r u c e w o o d are soluble , these values Increased in rod samp les taken from the halls after 1 year to some a n d i i % , r e s p e c t i v e l y. In t h e o u t e r r e g i o n s o f a core from a 7 0 y e a r s o l d b e a m t h e a l k a l i • ere e x t r a c t r e a c h e d even 7 0 %. From t h e r a t i o o f t h e e x t r a c t a m o u n t s ( Na0H : H 0) ? it was found that low values generally indicate severe changes in the cell walls as considerable portions of polysaccharides and lignin become soluble even during water extraction . CONCLUSIONS ficant Indicator with respect to wood condition 25 technique give progress to aggressive informations of a t m o s p h e r e s. about degradation - to their condition the effects The initiation which macroscopically Invisible , but may f a t i g u e o f w o o d c o n s t r u c t i o n e l e m e n t s. are cause a On the other hand it was demonstrated that wo d degradation is normally restricted most regions of structural to the outer - t i m b e r. A d d i t i o n a l l y the cell tissue structure remains rather stable e v e n i f c e l l w a l l m a t e r i a l i s d e g r a d e d. REFERENCES 1 BESOLD , G., F E N G E L , D. .s uchungen der - Systematische Unter W t r k u n g a g g r e s s i v e r G a s e auf H o i z Roh W e r k s t o f f 4 1 s c 2 7 J 3 2 , - f v s • e m a t i s c h e ntersuchungen der Wirkung aggressiver Case Flchtenh olz. H o l z Roh - W e r k s t o f f 1 * 5 0 93 ( 1983 ) F l c h t e n h o l z. 265 269 , 333 337 ( 1983 ) 2. FF. NGEL , D. , HARDELL , H . L. - - ? * . r Jack Pine , Sulphite , Quinones, Chemimechanical Pulp, pH, Refining Energy, Pulp the yield to 80-90 % range. In our r e c e n t paper ( 10 ), it was firstly demonstrated t at t quinone pulping aid can be employed in spruce SCMP process at nearly neutral liquor pH of 7. for improved pulp strength properties , At thi liquor pH, the pulp brightness was unarCected the pulping aid . Earlier , Nomura ( 11 ) hat!• employed anthraquinone in calcium bisulphite 1 yield pulping and found that the presence of quinone during sulphonation resulted in higher yield , brighter and s t r o n g e r pulp, Our furthe investigation revealed that the quinone pulpirn aid was effective for preferential delignification of black spruce chips even in the chemimechanica 1 pulp yield range a n d at sulphite liquor pH of 6 and 7, although its efficacy increased with increasing n alkalinity ( 12 ). In order to ootimize cooking conditions capable of producing reinforcement quality of chemimechanica 1 pulp from jack p i n e , the effect: of cooking liquor pH ranging from 6 to 10 with and without SAQ ( disodium salt of 1 , 4 - dihydro 9, 10- dihydroxy anthracene ) were investigated . For comparison , dispersed and powder AQ ( anthraquinone ) were also included in this study. The amounts of residual quinone in the cooking liquors for some cooks were monitored quantitatively. Molecular size distributions of 1 ignosu 1 phonate from some typical cooks were Strength , Yellow Coloration , Alum. compared. The pulps produced from various cooking liquor pH levels with and without SAQ INTRODUCTION addition were characterized for pulp strength , refining energy demand and bleachabi 1 ity with both hydrosulphite and hydrogen peroxide. T h e yellow coloration of jack pine chemimechanica 1 pulps with aluminium ions and methods for reducing this undesirable coloration are also described in this paper. CHEMIMECHANICAL PULP FROM JACK PINE BY SULPHITE/QUINONE PULPING C.H. TAY & S.E. IMADA ABITIBI - PRICE INC. CENTRAL RESEARCH DIVISION SHERIDAN PARK , MISSISSAUGA , ONTARIO , CANADA L 5K 1 A 9 ABSTRACT A satisfactory reinforcement jack pine chemimechanical pulp much s t r o n g e r than spruce SCMP can be produced by su 1 phite/quinone pulpin process. Within the cooking liquor pH range ( 6- 10 ) studied , the addition of 0.1 % SAQ on dry wood promoted deIignificatlon , thereby giving a s t r o n g e r pulp with less refining energy demands. The efficacy of SAQ increased with increasing liquor pH. The pulp brightness was adversely affected by the use of quinone pulping aid only at the liquor pH of 8 or higher . Dispersed AQ outperformed powder AQ and was quite comparable to SAQ in catalytic action. Alum used for pitch deposition control can cause yellow coloration of the resultant pulp, and more work is needed to better understand the mechanism and to find effective ways for overcoming this problem . KEYWORDS: Jack pine ( Pinus banksiana ) is well underutilized in Canada as pulpwood for newsprint manufacture , due to it high extractive content and thick - walled tracheids ( 1 ). Alkaline sulphonation of chips followed by atmospheric refining produced ultra - high yield pulp with good removal of extractives but the pulp quality was markedly poorer than that from black spruce ( 2, 3 ). Introduction of quinone pulping aid under alkaline sulphonation conditions accelerated delignification. The chemimechanica 1 pulp produced from sulphite /quinone cook showed a significant improvement in interfibre bonding , and was considered sufficient as reinforcement pulp for newsprint manufacture ( 3 ). Nevertheless, the Pulp brightness was low, and thus bleaching i s required . Traditionally, sulphite/quinone pulping has been conducted under certain alkalinity either Using Na 2 SOj alone, or in combination with N *OH , Na COj or NaHCOj to produce pulp 2 yield up to about 75% ( 4 — 7 > . Work done by Nomura ( 8 ) # Fleming ( 9 ) and Tay ( 3 ) had extended EXPERIMENTAL Jack pine trees of 68 years old grown in Thunder Bay area were used for this study , The p r e p a r a t i o n of pin chips, pilot plant c o o k i n g and refining equipments were described before ( 1 ) Unless otherwise specified , the p i n chips were cooked in the batch digesters using . 10 mins presteaming , 10 % as Na SC> , liquor 2 3 to wood ratio of 6: 1, 15 m m s to and 45 mins at maximum temperature of 170°C and 0.1 % q u i n o n e based on dry wood if required . Two series of experiments were run. In the first series only control cooks were made to investigate the effect of cooking liquor pH alone. In the second series , these cooks were repeated and similar cooks with SAQ added were In both s e r i e s, duplicate also performed . 137 batche s were cooke d for each condit ion to provid e suffic ient chips for refini ng. Throug hout most cooks liquor sample s were Table I DATA r «OH CH[MlMECHANICAL PULPING Of JACK PINE WITH LIQUORS Of VARIOUS pH period ically withdr awn for TOC determ inatio n using an Astro Model 1850 TOC TC Analys er. SAQ - . 138 88.7 86.8 87.7 77.89 77.00 5.04 5.46 27.93 27.46 4367 63 No 4413 14 4416 16 No 1 3485 1764? Tei 14898 87.0 87.1 86.3 77.0 19.05 5.35 6.87 77.36 75.9? No No 5 . 6? ------- 4417 18 7 8 10 1 lignin Content In Pulp , 1 FTTTon A'cia lolubVe TotiT - 4360 61 4409 10 4411 17 14761 85.0 Ye* 14169 18860 84.5 78.8 70.99 15.84 6.69 76.61 77.53 4358 59 4406 06 4407 08 No No Yes 14608 14676 71195 84.8 83.1 74.9 70.16 15.49 6.43 5.80 71.79 76.59 101 «* Na?S03, L/W »6:1 15' lo end 45’ at 170*C Pin chip* Uncooked chip*: 79.571 Klason and 0.041 acid soluble lignin - 4405 to 4420 were from the second series. It is obviou s from this table that the cooked chip yield increa sed with decrea sing liquor pH , but the higher yieldi ng pulp also contai ned more lignin. This trend became much more pronou nced for the cooks with SAQ added. While SAQ additi on decrea sed the cooked chip yield , it did so by prefer ential delign ificat ion as demons trated in Figure 1. The remova l of extrac tives during chip sulpho nation was notice ably poorer at liquor pH 6 than at pH 7 or higher , confir ming our earlie r findin g( 2). Figure 1 EFFECT OF COOKING LIQUOR pH ON KLASON LIGNIN C O N T E N T O F J A C K P I N E C. M P 6 pH tOO z - pH betwee n A to 10 on SAQ perfor mance was invest igated and the pertine nt data are given in Table 1 Cooks 4358 to 4165 were from the first series , while Cooks 11038 10968 11865 4419 70 - Liquor pH and Pulpin g Rate The effect of cookin g liquor No No Yes 4364 66 refine the bulk of the materi al in multip le passes for other charac teriza tions. Klason lignin determ inatio ns were made on the first RESULT S AMD DISCUS SION Tteld 6 Waring Blendo r to provid e an initia l cooked bright ness , but the Bauer refine r was used to - TOC ppw Coo* No. For all cookin g condit ions , cooked chip yields were determ ined. A sample of cooked chips from each condit ion was defibe nzed in a pass pulps after extrac tion with dichio rometh ane. Labora tory bleach ings of the first pass pulps with hydrog en peroxi de or hydros ulphit e were carrie d out in accord ance with our standa rd proced ures(10). All the reflec tance curve s were obtain ed on Varian DMS 90 UV/Visble Spectr ophoto meter with Diffus e Reflec tance Access ory. The pulpin g testin gs were done based on TAPPI standa rd method s. SAQ as 20% active solids was acquir ed from Kawasa ki Chemic als in Japan , wherea s both powder AQ and disper sed AQ at 50% solids were obtain ed from CIL and were used as receiv ed withou t purifi cation. The amount s of residu al AQ in the cookin g liquor s were determ ined by HPLC using a Varian Model 5000 equipp ed with Variab le Wavele ngth Detec tor UV 50 and CDS 111 Data Proces sor. The proced ure for extrac ting quinon e compou nds from the cookin g liquor was the same as that descri bed by Mortim er(13). A gradie nt elutio n with aceton itri 1/water using a revers e phase column MicroP ak MCH 5 and 254 nm UV detect ion and extern al standa rd calibr ation cur ve. Both peak height and area count showed a straig ht linea r rela t i ons.i i p with AQ concen tratio n betwee n 1 to 75 ppm. Molecu lar size distri bution s of lignin dissol ved in the cookin g liqjor s were charac terize d by gel filtra tion chroma tograp hy using the same HPLC with a MicroP ak TSK Gel 2000 SW Column and 280 nm UV detect ion , The column has a molecu lar exclus ion limit of 2 x 104. The sample s were filter ed throug h a 0.45 u membra ne and no futthe r diluti on was made prior to the inject ion . Add‘ n. Liquor pH a O 19 19 a J o I\ S A O o J 17 17 tc * . 15 0 7 9 8 COOKING LIQUOR pH 10 75 60 PULP 65 Y I E L D, \ 90 There was a strong relati onship betwee n TOC value of the final cookin g liquor and cook yield , showin g a correl ation coeffi cient of 0.954 for all the cooks listed in Table 1. Knowin g this, a plot t f cookin g TOC as a functi on of cookin g time for the variou s cooks reveal ed how readil y cooks can be accele rated »y increa sing liquor pH as depict ed in Figure 2. At each pH level tested , the additi on of SAQ was shown to furthe r accele rate the cooks . * Liquor pH and Refini ng Energy Demand The effect of cookin g liquor pH on refini ng energ y requir ed to achiev e a given CSF was not Figure 2 E F F E C T S O F S A Q ANO L I Q U O R Figure 4 ON PULPING RATE SAG pH .• S A O Pin Chips t0 o 15 To 4 5 Ac 1 7 0 C 10 * As NA SOJ L W 6: 1 . * Control r/ *> 35 Control V/ ir ,*' Z 6 O £Z a o SAQ 0 13 3 8 6 « J 3 Pass 4 6 / A o 20 40 COOKING T I M E , Given the same bleach ing condit ions (1 % 60 Na ) - S 20 m i n s at 65 C for 15 hrs at 3% consis tency or 2.5% H 202 and 2.5% total alkali at 50 C for 2 hrs at 12 % consi stenc y) most pulps approa ched the same bleac hed bright ness , regard less of initi al pulp ° change d (Figure 3). bright ness as depict ed in Figure 5. Thus the lower initi al bright ness of the pulps from cooks at pH 8 and 10 is not of immedi ate conce rn . While the hydros ulphit e was very effect ive in bleach ing the pH 8 and 10 pulps , it did little for the bright ness of pH 6 and 7 pulps Figure 3 EFFECT OF COOKING LIQUOR pH •>. -OE 7 \ ON R E F I N I N G ENERGY \vN \ \ ' X\ UJ UJ CC CL a 5 < o 2 < » »* • V. X 5 X• v\ \ % 1 ** S e r i e s \ B L E A C H A B I L I T Y OF 4 •• \ o Figure 5 v\ \ £4 Peroxi de was more effect ive here , but again , these pulps were very diffic ult to bleach. It is obviou s that bleach ing condit ions need to be optimi zed for indivi dual pulps. 6 \ \ \ \ at . A l * 2 DEMANO .1 % SAQ 7 4 Series 'A < O AS A pH pH 7 pH 6 3 + 75 LIQUOR 60 \ 3 JACK P I N E C M P FUNCTION OF COOKING pH 10 pH 8 % 55 ° ^ perfe ctly clear. While chips cooked at pH 6 defini tely consu med the least energy during refini ng , the two series of cooks did not show the same energ y consum ption trend as liquor pH 35 Control 55 ' / 2 CO UJ QC / // ' 4 40 O Z 45 UJ O X / 4 T i/ * / s yy ykf // . y / 2 £ 40 . SAQ / 8 8 2 < n |4 5 Control . O * o UJ 6 PH 6 £ 50 onirol ' d M PH 7 i 14 $ 10 * PH 8 AO LIQUOR PULP BRIGHTNESS * 55 a O u ON 60 O M pH ^ = ia E F F E C T S O F R E F I N I N G, S A Q A D D I T I O N A N D 95 35 R E F I N I N G ENERGY, 55 75 95 «/> H P O 0D T A trend might have been marked by the lack of strict contro l on horsep ower applie d at each pass. Nevert heless , the addit ion of SAQ reduce d energ y demand s for all the cooks with the pH 10 cook having the most dramat ic energ y reduct ion over the contro l. Much more savin gs in refini ng energ y can be realiz ed by SAO additi on if compar ison is made on the basis of interf ibre bondi ng (see Table III ). UJ 55 50 5 45 SAQ did not harm the bright ness. 0 Unbleached Q NAJSJO, a 00 40 ° M3 3 35 < cn UJ UJ a at CD 55 60 liquor pH and Pulp Bright ness Cooks made at liquor pH 8 and higher lower ed the pulp bright ness as illust rated in Figure 4. The additi on of SAQ at alkali ne pH droppe d furth er the bright ness. Howeve r at pH 6 and 7, C Control C SAO C SAO C SAO C SAO Compar ison of Variou s Quinon e Produ cts In our earlie r study , it was pointe d out that SAQ was more effect ive than THAQ and powder AQ as based on TOC in cookin g liquor and cookin g time relati onship( 3 ). Wandei t(14 ), compa red the 139 l - catalytic efficacy of DDA (1 , 4 dihydro 9 ,10 dihydroxy anthracene) and powder AQ in both soda and kraft pulping processes using a rotating digester with forced circulation of the liguor and another stationary digester without forced circulation of the liquor , and concluded that DDA was superior to AQ due to its better solubility and lower redox potential. Catalytic actions of SAQ, dispersed AQ and powder AQ were compared using jack pine pin chips with 10 % as Na 2 S0 3 at PH 8 for a total cooking time of 95 mins including 15 mins to reach 170°c. The dosage rate of quinone compounds was kept at 0.1 % on dry wood , The cooking liquors at certain intervals during the cooking cycle were withdrawn for TOC , residual quinone and gel filtration analyses, The cooked chips from these cooks were not refined. The TOC values as a function of cooking time are depicted in Figure 6. Apparently the dispersed AQ outperformed powder AQ and became quite comparable to SAQ. All the three pulping aids indeed accelerated the pulping rate markedly. At the cooking liquor pH 8, SAQ was present as slightly yellow fine colloids which were identified as DDA. DDA was readily converted to AQ before reaching the maximum cooking temperature as revealed by HPLC and UV spectrophotometric analyses. Figure 6 - I Figure 7 CONCENTRATION OF OUINONE COMPUND IN COOKING LIQUOR # SAO 100 J a c k P m# P m C h i p BO 10 \ E a a cr o D o J o * * o ° Oumona Addad : 170 ppm 40 O 20 2 o < COOK I MG 1 0 % A t NtjSO)• TSK 2000 SW to . p H 0, 1 5 ii .• Control X Powdtr l 1 0 % A t M t SOj I P' ° 1 5 To A 8 0 At 1 7 0 C 0 20 40 60 , 80 i $ | C O O K I N G T I M E , m i n t. t fi . • I* • i -- *» * »j* v ’ « • . - dispersed into the cooking liquor , and tl i s undoubtedly contributed to its relatively poor ’ ormance. At total cooking time of 1 hr , the icSidual amounts of AQ were 14.7 % , 14.1 % and 4.7 v of the initial quinone added fo 4 . Q , dispersed AQ and powder AQ cooks resp ** * ive . y . - 140 ^ \ \ i\ I i i •F iI I IA - *S mint /t 4 !i V«r \ 4 ~ 6 :1 f\\ A '' tl * V. V * 10 1 I f •i u 9 j mint 14 2 6 10 14 2 I \ 6 10 I 14 mint , 100 * amounts of free quinone compound present as AQ in the cooking liquors were monitored by HPLC an4 the results are shown in Figure 7 Note that for the cook with powder AQ added , only 7 ppm free AQ was detected at the first 2 mins , compared with 102 104 ppm for the other two , suggesting that powder AQ was not readily Ihp SAO I* I (!\ RE TENT I O N T I M E, t II I I it 2 ^v pH 8 ii Ditportod AQ II i o Pin Chipt 6 i! iI I I .2 M O ii •» i« ii I * o 10 I n • 1a .4 r"+ C o n t r o l 15 ° 11 AQ 120 To / 8 0 A t 170 C UV 280 nm 10 tuft ' o 100 80 . mint GEL F I L T R A T I O N CHROMATOGRAPHY OF COOKING LIQUORS E a . Figure 8 X Ditperttd AO • TIME Lignosulphonate present in the cooking liquors for the SAQ , dispersed AQ and control cooks were characterized by gel filtration chromatography. The results as shown in Figure 8 revealed that at a given cooking time , the ii i •6 20 60 40 20 0 o SAG * 1 5 To / ® 0 A t 1 7 0 C 60 .8 25 * NtjSOj A pH 6 » V A R I O U S OUINONE COMPOUNDS ON P U L P I N G R A T E AQ A Powder r EFFECT OF O i t p« r t » d A Q O * amounts of lignin dissolved in the cooking liquors were much less for the control than for the other two cooks. In all cases, the dissolved lignin showed two dominant peaks. It seemed likely that the presence of quinone pulping aid did little , if any , to reduce the molecular size of 1 ignosulphonate• Obviously , more work is needed to study the mechanism of rapid de 1 ignification brought about by anthraquinone under nearly neutral pH and in the chemimechanica 1 pulp yield range. Cooking Liquor pH and Pulp Strength All the cooked chips listed in Table 1 were atmospherically refined and the pulps at various CSF levels were tested for stren th propertie s. Figures 9 and 10 clearly showed that pulp bonding strength and sheet density were affected by the cooking liquor pH. With lower liquor pH , pulp strength was reduced , hence energy savings that were noted during refining may not be savings at all , because the pulp requires more refining to lower freeneses to attain equivalen t strengths. While strength and density increased as liquor pH was raised from 6 to 7 to 8, additiona l increases in liquor pH to about 10 gave no further strength improveme nt , unless SAQ a given burst index , and thus a dristic reduction in refining energy deman i and hinher tear strength are attainabl e. Table II < 400 al CSf ) Coapjnson of Pulps at Constant Freeness | Powrr (HPO/OOT) pH Control SAO 6 76 7 8 10 71 84 8S 83 8» ( a -- i 78 i Control 61 i 71 | 3.1 41 B L SAQ 3.0 3.7 3.8 -131 72 . . ( k a) Burst Irvlca Control t 3.3 * 101 3.9 * 261 S.2 *401 6.0 *4Sl 6.2 S.S Densiti SA3 S , t . 464 ...S436 .S04 .9'. . .S0004 S64 *1 V. S S *61 6.4 •18 \ 7.4 * 233 8.0 « 291 . ~ Control t . 5.2 5 4 464 .s«o *is: Table III Ccc anson of Pulps at Constant Burst Strength ( 3 . J Ft» /Lg) ^ Control ( 2nd seriesl Figure 9 t • EFFECT OF COOKING LIQUOR pH ON BOMOI MG STRENGTH OF JACK P i ME C M P B .L . Tear Dcnsit ) P ' er CSF B L Tear Dtnsitv Power < 5.5 < 6.7 < 460 6.0 S 7 5.9 > 87 6.9 81 8.1 .. 95 78 75 3S0 492 7.2 . 480 625 5.9 5.9 5.9 650 5.5 78 67 45 . 480 a o 7 # — X X o Z 6 UJ X iS CC 4 CD 400 500 600 C A N A D I A N S T A N O A R D F R E E N E S S, 36 * - * < 3 300 460 ..430 .370 8.5 9.7 9.9 Yellow Coloratio n of CMP with Alum Acid sulphite pulp from jack pine is prone tc yellow coloratio n with aluminlm ions , The formation of galangin from pinobanks in which is present in jack pine heartwood was considere d tc be the mechanism as illustrat ed in Figure 11 proposed by Chapman(15 ). A series of chemi mechanica l pulps from earlier cooks at various liquor pH levels after bleaching with Figure 11 A E * .. t i% SAQ 6 - ..494 472 e Mo - CSF 6 * 300 7 31 S 6 450 10 453 i* f MECHANISM OF BELLOW COLORATION W I T H ALUM 700 ml .1l NaHSO 1 I •I • Figure 10 SHEET :i . . O E M S I T V O F J A C K P I M E C M P. A S A F U U C T I O N O F C S F Pmobinkim 4 A; 11: a I No pH SAQ 6 Al I\ 1% SAO i. I I i i *l I : # E 10 « x A I F / i' i i - I .1 :i . iV * \ z \ 220 *J : I \ s/ . »• S V \ / • i i -* "i: \: \ .i I > ** i »: * :« i : \ r> E u Galangin 340 UJ UJ \ *«, N 460 460 220 340 W A V E L E N G T H, n m Figure 12 X (ft 3 300 400 SOO DIFFERENTIAL REFLECTANCE CURVES OF PULPS TREATEO 600 WITH C A N A O I A N S T A N O A R D F R E E N E S S, m l ALUM 100 x was added to the cook. Note that tear strength seemed unaffecte d by the liquor pH or SAQ addition , and was highly dependent on CSF of the Pulp. Table II and III summarize more clearly the effects of Liquor pH and SAQ addition on pulp strength and energy consumpti on. Based on 400 the SAQ addition improved burst index by 9 10 45% and breaking length by 6 29 % over the - - HydrotuKMa iV / * 80 \ '/ N '\ x. / u V. . / Z Bleached / \ < Cooking LiQuor pH / • Ui 6 7 8 60 10 12 ° 100 Ui * -. . u * X Ui a 80 i ^ ^- rrr r j:, r . r. ". .** Paioiida B l e a c h e d control . The strength gains increased with Increas ing liquor pH. The pulps from SAQ cooks Can have much higher CSF than for the control at 60 400 500 W A V E L E N G T H 600 . nm 141 < I I hydros ulphit e or hydroge n peroxid e were subject ed to alum treatm ent , and the differ ential reflect ance curves for these pulps are shown in Figure 12. Obvious ly all these Figure 13 STRENGTH PROPERTY OF CHEMIME CHAN I CAL P U L P S AS A F U N C T I O N O F C O O K I N G L I O U O R p H pulps gave similar yellow colorat ion with alum as bisulph ite pulp from the same wood species. However , the extent of the yellow colour formed decrea sed with increas ing alkalin ity of the cooking liquor. Alkalin e hydroge n peroxid e bleachi ng was of great value for reducin g the format ion of yellow colour. Pretre atment of the pulp with stannou s compoun ds was also found to be useful for avoidin g this undesir ed colora tion(16). It remain s to be learned as to whether or not the formati on of galangi n would take place at the much higher cooking liquor pH than that for bisulph ite. TCMP from jack pine with sulphit e treatme nt was found to give no yellow colorat ion with alum. Our earlier study(2) suggest ed that three or more compoun ds extract ed from the cooking liquors exhibit ed yellowi ng in thin layer chromat ography after sprayin g with alum. Extract ion of pulps With organic solvent s did reduce but not elimin ate the yellow colorat ion. These suggest that the formati on of galangi n during sulphon ation may not be the sole mechani sm for the yellow colorat ion , More work is underwa y to clarify the mechani sm , and thus to devise a more effecti ve Way for its J a c k P i n a ( P m C h i p s) 9 u* ‘ °E 0.1 % SAO No 0 SAO B S ( Yiaid ) o / *> E 7 87 vO X 86 O Z 6 UJ O z 5 *< Ui CE m 4 7 COOKING L I Q U O R pH Figure 14 STRENGTH PROPERTY OF CHEMIMEC HANICAL PULPS AS A FUNCTION OF COOK YIELD ( AT 4 5 0 m l C.S J J J « Ck Pm 9 * O 0 1 % SAO Black Spruca « 0 1\ S A O o No SAO 8 E 10 i i 7 O z a Ui O 6 Z x . prevent ion < UJ a CO 5 3 75 Chemime chanica 1 Pulps from Jack Pine and Black Spruce - Physica l strengt h propert ies of chemi mechan i ca 1 pulps from jack pine ( pin . ' hips ) by sulphit e/SAQ cooking were compare d wi those from black spruce (PSF chips) in Figure 13 as a functio n of cooking liquor pH, and in Figure 14 as a functio n of cooked chip yield , The data for chemime chanica 1 pulps produce d from black spruce were taken from our earlier work( 12), using the same cooking conditi ons (10% as Na ^ 2 SO 3' 15 mins to and 45 mins at 170 c). • The benefic ial effect of SAQ on interfi bre bonding was also realize d in black spruce in all liquor pH ranges studied. In Figure 13 it is demons trated that th? jack pine pulps from pH 6 and / cooks with SAQ were notice ably weaker than spruce pulps produce d without the pulping aid , but the former became stronge r than the latter from pH 8 and 10 cooks and were closer to that if black spruce with SAQ additio n When the compari son was made on the basis of cook yield as depicte d in F ; iure 14 , it is very obvious that the cooking liquor pH played a very profoun d role in affecti ng both yield and pulp ^ ° » eo 65 C O O K 90 75 00 85 90 Y I E L D , \ strengt h charact erist )cs , and the signifi cance was amplifi ed by the additio n of quinone pulping aid Note that for all co < s with SAQ added , . ^ chemime chanica 1 pulps from jack pine were always inferio r in interfi bre bonding to that from black spruce at a given pulp yield , However , the jack pine pulp at a cook yield of about 83 % became almost equal to that from spruce cooked to 86 % yield without rAQ. CONCLUS IONS 1. Jack pine pin chips were cooked at 170 C ° with 10 % as Na SO for 50 mins includi ng 15 mins to reach the maximum tempera ture ^ ^ under various liquor pH of 6, 7, 8 and 10. The cook yield decreas ed from 88 % to 84 % with increas ing liquor pH for the control , and 87% to 75% for the cooks with 0.1% SAQ additio n on dry wood. . 142 O i l SAG B l a c k S p r u c a ( PSF C h i p s ) 2. The additio n of SAQ acceler ated deligni ficatio n within the pH range st died , but its efficac y increas ed with increas ing 1 iquor alkalin ity. 3. Cooking liquor pH was an important parameter affecting yield , quinone performance , pulp C.H. Tay , R.S. Fairchild and D.F. Manchester ( J. of Pulp and Paper Science J 0 No. i, 3. _ - 134 139 , 1984. brightness , rofining energy demand and pulp strengt'. 4. . Pulps from pH 6 cooks were noticeably higher in yield and brightness , but weaker in interfibre bonding regardless of SAQ addition or not. 5. D.W. Cameron , A. Farrington , D.F. Nelson , W.D. Raverty , G.L. Samuel and N. Vanlerhook , Appita 3JS No. 4 , 307- 315 , 1982. _ - R . Pusa , Paperi ja Puu , 6 3 No. 11 , 663 666 , 1981. 5. The addition of SAQ improved burst index by 10 to 45 % and breaking length by 6 to 29 % over the controls , and the improvement increased with increasing liquor alkalinity. 6. 6. 7. Dispersed AQ outperformed powder AQ and was comparable to SAQ in catalytic effect. The quinone consumption during cooking was very rapid . At the 60 mins cooking time ( including 15 mins to temperature) , only 14.7% , 13.5% and 4.7% of the total quinones added were identified as free AQ for SAQ , dispersed AQ and powder AQ cooks J. Kettunen , N.E. Virkola and I . Yrjala , Paperi ja Puu 61^ No. 11 , 685 70C: , 1979. - 7. I ( . O.V. Ingruber , M. Stradal and J A. Biste I , Pulp and Paper Canada 8 3 No. 12 , T 342 T 349 , _ - 1982. 8. Y. Nomura , M. Wakai and H. Sato , Jap. Pat. Kokai 112 ,903 , 1976. 9. B.I. Fleming , M.C. Barbe , K. Miles , D.H. Page and R.S. Seth , J . of Pulp and Paper Science 10 No. 5, 113 118 , 1984. - respectively. . C.H. Tay , R.S. Fairchild and S.E. I made , * 10 . 8 9. Molecular size distribution of lignin dissolved in the cooking liquors from the cooks with pulping aids showed no discernible difference from the control. Chemimechanica 1 pulps from jack pine react with alum to form yellow colour , and the mechanism remains to be learned. 10. Jack pine chemimechanica 1 pulp at cook yield of about 83 % by sulphite/quinone pulping is comparable to that of spruce at 86 % yield from the same sulphite cook without the pulping aid. 11. Sulphite/quinone pulping at pH 7 to 8 is considered a useful process for making a reinforcing quality chemimechanica 1 pulp from jack pine for newsprint manufacture. - TAPPI Pulping Conference , Book 2, 319 325 , San Francisco , California , November 1984. To be published in TAPPI. 11. Y. Nomura , M. Wakai and H. Sato Cadn . Patenl 1 ,079 ,906 , 1980. 12. S.E. Imada , R.S. Fairchild and C.H. Tay , CPPA Annual Meeting , Technical Section A 139 145 , Montreal , 1985. - i 13. R.D. Mortimer and B.I. Fleming , TAPPI £4 No. 11 , 114 116 , 1981. - £ No. 11, 14. P. Wandelt , Paperi ja Puu 6 673 681 , 1984. - I . 15. R.A. Chapman , H M. Nugent , D.W. Clayton , D.F. Manchester and W.A. Redmond , CPPA Trans. Techn. Sect • r l No. 4 , 122 129 , 1975. - REFERENCES 1 . C.H. Tay and D.F. Manchester , Canadian Wood Chemistry Symposium , Extended Abstracts: 109 114 , Niagara Falls , Ontario , September 1982. - 2 . ^ 16. C.H. Tay and R.S. Fairchild , TAPPI Research and Development Conference , 229 234 Appleton , Wisconsin , September 1984. - C.H. Tay , R.S. Fairchild and D.F. Manchester , International Symposium on Wood and Pulping Chemistry , 2: 28 35 , Tsukuba Science City , Japan , May , 1983. - 143 n one approach to this problem , we have f e r entated SL to butanol by C . ostridium ac *' Duty 1 icum and by Cl. butyricum strains which uti . ize both hexoses and pentoses. In a previous paper ( 2), we reported the fermentation of a 5 sugar solution simulating the sugar composition of SL , and identified conditions for producing butanol acetone-ethanol solvents in yields above 0.36 g solvent/g sugar utilized , and at the same While these time over 96 % sugar utilization , substrates did not contain lignin or the other humic substances present in spent sulphite liquor , our success encouraged us to pursue this approach. ' • FERMENTATION OF SPENT SULPHITE LIQUOR TO BUTANOL AND ETHANOL - SHI YUAN YU and MORRIS WAYMAN FACULTY OF FORESTRY - UNIVERSITY OF TORONTO TORONTO, ONTARIO MSS 1 A 4 INTRODUCTION J #•9 " In the Ontario Paper Company mill at Thorold , Ontario , spent sulphite liquor (SL) is processed to make alcohol and vanillin ( 1 ). Analysis of a recent sample of this liquor is shown in Table . 1 Table 1. Composition of Spent Sulphite Liquor In another approach , we fermented SI with the pentose fermenting , ethanol producing yeast , Candida shehatae ( 3 ). With this yeast we had obtained good xylose utilization at acceptable rates of ethanol production under conditions which appeared to lend themselves to industrial operation , using pure sugars. We now report the application of this fermentation to SL. - - q/l Pretreatment of Spent Sulphite Liquor 1 ignosulphonic acids as lignin * sugars: mannose glucose galactose xylose arabinose 67.69 15.61 5.20 7.15 7.80 3.25 * In addition to these monomeric sugars , there are oligomeric carbohydrates , which may amount to 30% of total carbohydrate , formic acid , acetic acid , furfural and acid soluble lignin fragments. - Following a partial removal of free S02 by heating , the liquor is brought to pH 4.5 with lime , and fermented to ethanol , The yeast used is Saccharomyces cerevisiae , bakers' yeast , The residue from the alcohol distillation contains lignin and unfermented sugars , and is then processed further , by adding a catalyst and heating under pressure with air to oxidize the lignin to vanillin. Since the objective of this study is to effect more complete removal of the sugars from the lignin , while the lignin must remain for conversion to vanillin , we are constrained from removing the lignin prior to fermentation , We report our results in removing the volatile inhibitors. Samples of SL from Ontario Paper Company were fed to a packed tower , with a countercurrent steam flow. In this way , the pH was raised from 2.6 to 4.5 or 4.7. The concentration of toxic substances, namely formic acid , acetic acid , and furfural , in the liquor was determined by gas chromatography , The total concentration of these was reduced to less than 6% of their original concentration. For butanol fermentation , the SL used was steam stripped to pH 4.7, and for ethanol fermentation , to pH 4.5 oxalic acid Adaptation for Butanol Fermentation Since the vitilizes only fermentation to ethanol the hexoses , the pentose sugars , which amount to 28 % of the monomeric sugars shown in Table l remain , and are present in the vanillin reactor , where they are oxidized to organic acids and add to the cost of vanillin product ion For this reason a fermentation process for utilization of both hexoses and pentoses is desirable. present Although pure sugar butanol fermentation has shown excellent results ( 1 ) and the concentration of toxic substances had been minimized by steam stripping , SL was still difficult to ferment in the presence of its l ignosulphonate and other phenolic substances. Adaptation was carried out following heat shocking and 10 to 16 h incubation in corn 9 teep liquor medium ( CL ), transferring to 145 40% SL, 60% CL for 12 to 18 h , then to 70% SL , 30% CL for 16 to 24 h , the resulting cultures being used as inocula. No adaptation to steam stripped SL was required for fermentation to ihanol . The production of ethanol from spent 3. sulphite liquor by C. shehatae is better than by S. cerevisiae by a significant margin , 32% , and sugar removal is more complete by about 58%. Thus it has the potential for being substituted for S. cerevisiae in industrial ethanol produc RESULTS AND DISCUSSION 1. Butanol Fermentation tion where pentose sugar concentrations are s ign i ficant. It can be grown on spent sulphite liquor without adaptation. - - This is the first report of butanol fermenta tion of undiluted SL containing 1 ignosulphonate • Sugar removal in these fermentations was incom plete , 73.3 to 84.4 % of original hexoses plus pentoses being fermented by these bacteria. Total solvent production , butanol plus acetone , was 0.18 to 0.25 g solvent/g initial sugar. This is substantially less than obtained with a pure sugar mixture simulating SL, 0.36 g solvent/g sugar. Growth was vigorous. Various additions to the medium were tried , but none of these improved sugar consumption or solvent yield. Thus only a partial success can be claimed. ACKNOWLEDGEMENTS - This work was supported in part by the Natural Sciences and Engineering Research Council of Canada. REFERENCES 1. CRAIG. D. Justification for pulp and paper byproduct development. Am. Inst. Chem. E. Symp. Series No. 133 69: 1 5 ( 1973 ). - - 2. WAYMAN , M • I YU , S. Acetone butanol fermenta tion of xylose and sugar mixtures. Biotech. Letters 7: 255 260 ( 1985 ). 2. Ethanol Fermentation The results of these fermentations showed that shehatae is more effective at sugar removal C. from SL than is S. cerevisiae , the improvement in ar removal being 58.0% ; and also in production V *. alcohol , the improvement being 32.0%. Sugar fermented by C. shehatae was 88 % , while S. cerevisiae fermented only 56% , while ethanol production was 0.37 g/g sugar with O shehatae and only 0.28 g/g sugar with S. cerevisiae. / - 3. DU . - - Spent s u l p h i t e liquor contains m a n y inhibitors. Most of these are removed by steam stripping , particularly when this raises the pH to 4.3 or higher fermentation . . - 2 Two butanol producing microorgan i sms studied here are adaptable to growth on steam i stripped spent sulphite liquor , However , while jrowth is vigorous , solvent production was well :"'low that experienced w i t h pure sugars ( 0.25 g solvents/g i n i t i a l sugar compared to 0.36 with the pure sugar mixture ) and sugar removed was less ( 73.3 % compared to 96.6 % ). This is , lowever better sugar removal than experienced - . 'ith s. cerevisiae ( 55.7% ). 9 If butanol becomes a able product , for example as cosolvent in 1 iHe methan » 1 blends , butanol fermentation of pent HU 1 p h i liquor is likely technically - easxble. 46 * - J .C . , V A N of d xylose D E R W A L T , J . P. Fermentation to ethanol by a strain of Candida shehatae. Biotech. Letters 5: 357 362 ( 1983 ). PREEZ, CONCLUSIONS 1 - •• 40% SL, 60% CL for 12 to 18 hr then to 70% SL, 30% CL for 16 to 24 h , the resulting cultures being used as inocula No adaptation to steam stripped SL was required for fermentation to :hanol. . 3. production of ethanol from spent sulphite liquor by C. shehatae is better than by S. cerevisiae by a significant margin , 32% , and sugar removal is more complete by about 58%. Thus it has the potential for being substituted for S. cerevisiae in industrial ethanol produc tion where pentose sugar concentrations are s ignificant. It can be grown on spent sulphite liquor without adaptation. The - RESULTS AND DISCUSSION 1. Butanol Fermentation - This is the first report of butanol fermenta tion of undiluted SL containing 1 ignosulphonate. Sugar removal in these fermentations was incom plete , 73.3 to 84.4% of original hexoses plus pentoses being fermented by these bacteria. Total solvent production , butanol plus acetone , was 0.18 to 0.25 g solvent/g initial sugar. This is substantially less than obtained with a pure sugar mixture simulating SL, 0.36 g solvent/g sugar. Growth was vigorous. Various additions to the medium were tried , but none of these improved sugar consumption or solvent yield. Thus only a partial success can be claimed. ACKNOWLEDGEMENTS - This work was supported in part by the Natural Sciences and Engineering Research Council of Canada. REFERENCES 1. CRAIG. D. Justification for pulp and paper byproduct development. Am. Inst. Chem. E. Symp. Series No. 133 69: 1 5 ( 1973 ). - 2. WAYMAN , M • 0 YU , S. Acetone butanol fermenta tion of xylose and sugar mixtures. Biotech. Letters 7: 255 260 ( 1985 ). - 2. Ethanol Fermentation The results of these fermentations showed that C. shehatae is more effective at sugar removal from SL than is S. cerevisiae , the improvement in ar removal being 58.0% ; and also in production V * - - alcohol , the improvement being 32.0%. Sugar fermented by C. shehatae was 88 % , while S. cerevisiae fermented only 56% , while ethanol production was 0.37 g/g sugar with C shehatae and only 0.28 g/g sugar with S. cerev islae. / - 3. DU PREEZ , .7.C • 0 VAN DER WALT , J . P. Fermentation of d xylose to ethanol by a strain of Candida shehatae. Biotech. Letters 5: 357 362 ( 1983 ). - - ^ CONCLUSIONS . 1 Spent sulphite liquor contains many fermentation inhibitors. Most of these are removed by steam stripping , particularly when this raises the pH to 4.3 or higher . - 2. Two butanol producing microorganisms studied here are adaptable to growth on steam stripped spent sulphite liquor. However , while j rowth is vigorous , solvent production was well >' low that experienced with pure sugars ( 0.25 g •• olvents g / initial sugar compared to 0.36 with the pure sugar mixture ) and sugar removed was Less ( 73.3 % compared to 96.6 % ). This is , » owever , better sugar removal than experienced # i th S. ce > v isiae ( 55.7% ). If butanol becomes a • able product , for example as cosolvent in line methanol blends , butanol fermentation of pent sulpr : •• liquot is likely technically - > - oasible. 46 - - .• - Extraction of fresh mangrove leaves (Rhizo - MAJOR CONSTITUENTS OF FORESTRY MATERIALS? FLAVCLOGLYCANS GEOFFREY N. RICHARDS DIRECTOR WOOD CHEMISTRY LABORATORY UNIVERSITY OF MONTANA 59812 MISSOULA , MT (Work commenced at Department of Chemistry and Biochemistry , James Cook University of North Queensland , Townsville , Australia.) ABSTRACT A novel type of natural water soluble co polymer has been obtained in about 20% yield from mangrove leaves, Evidence has been obtained that the polymers contain covalently bonded flavolan and high molecular weight glycan com ponents . probably in a range of proportions and they ar designated as flavologlycans. Frac tionation of the polymers has been carried out by lead acetate conplexing and by sorption on polyamide and Sepharose. The previous litera ture on chemical constituents of leaves of other trees and of barks provides evidence that flavologlycans are very probably widespread and abundant in forestry materials. - - - - - KEYWORDS: - phcra stylosa) with water or with aqueous ethyl enediaminetetra acetic acid ( EDTA ) , after pre liminary extraction of pigments and flavonoid materials with hexane and hot acetone , yields about 20% of polymeric material containing approximately equal amounts of flavolan and gala :turonoglycan. The fractionation of this material and the composition and properties of the subfractions have been studied. The results provide reasonable evidence that the major portion of this extract consists of covalently bond ed copolymers of the two species (viz. flavolan and glycan ). The only previous report of a flavonoid poly saccharide compound appears to be by Markham (6) who isolated about 2% yield of what appears to be a related material by water extraction of liver wort. In this case , the molecular weight was about 32 0 per flavonoid unit and the polysaccha ride was bonded glycosidically via galacturonic acid to positions 7 and 4 (l)of 8 methoxyluteo lin. Our polymer appears to be present in the mangrove leaves in much greater amount and the gel chromatography and general viscosity behav lor suggest that the glycan component is of much higher molecular weight than the liverwort product. Galacturonic acid , arabinose , galac tose , rhamnose , glucose and mannose are the most abundant carbohydrate components , It is possible that the flavologlycans are of wide occurrence in plants , often in high yield. - - - - - - - - - - - - Flavologlycans , Leaves , Bark INTRODUCTION The class of natural polymers referred to variously as condensed tannins and flavotannins , or more recently as proanthocyanidins (1 ,2), or flavolans ( 3 ,4) have the general formula 1 with n varying from 2 to approximately 20 (1 ,2). The polymers are widely distributed , but occur most abundantly in the leaves , fruit , heartwood and bark of woody plants , from which they are normal ly extracted , in yields of up to approximately 3% , by aqueous methanol , ethanol or acetone ( 5). However , these conditions of extraction are such that , if any flavolans were covalently linked to polysaccharidic materials , they would remain in the insoluble residue. This possibility was first investigated with mangrove leaves which are known to contain large amounts of tannins. - 1 1 EVIDENCES FOR INTERPOLYMER LINKAGES Our evidences for flavolan glycan linkages may be summarized as follows: 1. Both flavonoid and carbohydrate constituents are retained during dialysis. 2 . Both flavonoid and carbohydrate constituents are sorbed by nylon , the major component is completely resistant to prolonged elution with water and both constituents are eluted with formamide. 3. Both flavonoid and carbohydrate constituents are sorbed by Sepharose. The major component is completely resistant to elution with water , but both constituents are eluted with increas ing concentrations of urea in water. 4. Treatment of the flavologlycan with chlorite and subsequent dialysis removes the aromatic components and leaves a glycan in the antici pated yield. 5. Treatment with acid removes the qlycan and leaves flavolans (now partly soluble in ethyl acetate) in the anticipated yield. 6. Flavolan ( non dialysable) polymer would not - - - 2 n - 147 be expected to be readily soluble in water , unlike the isolated flavologlycan , whereas the isolated flavologlycan was totally in soluble in all of the solvents normally used to extract flavolans , such as aqueous methanol or aqueous acetone (5). - FLAVOLOGLYCANS IN BARK? Bark remains a high volume , low value "waste" product of the forest products industry , especially from softwoods. Accordingly , the chemical constituents of barks have been exten sively studied with at least 200 research papers and patents published since 1967. The bulk of this research has concentrated on either poly saccharides or polyphenols which are the major constituents of bark by weight and no previous workers in this field appear to have found evi dence for covalent linkage of glycans to poly meric aromatic materials. In several instances , however , a reassessment of experimental results from earlier papers reveals that flavologlycans are almost certainly present in several softwood barks. Thus , Pulkkinen and Vaisanen (7) found in hot water extracts of Norway Spruce bark (yield 11 %) that polyphenols and carbohydrates both persisted through several molecular weight cuts when fractionated by ultrafiltration. The results would be compatible with presence of flavologlycan and pectin. Pulkkinen and Peltonen (8) also studied hot water extracts of Scots Pine bark (yield 16 %) by gel chromatography and observed behavior which was probably similar to our observations with flavologlycans , although they did not monitor columns for carbohydrate. Bailey and Pickmere (9) have extracted "hemi cellu)oses" from several barks without deligni fi cation and noted that all such " polysaccharide" fractions yielded only 25 35% carbohydrate on hydrolysis It is very probable that their fractions all contained major aromatic constit uent ? and that they include flavologlycans . Laver and coworkers ( 10) have found protein , tannin , starch and other polysaccharides in hot water extracts of the inner bark of Douglas Fir and these observations would be compatible with presence of flavolog 1 yeans. The polyflavonoids extracted by Hemingway and McGraw ( 11) from southern pine barks probably contain flavologly cans and these copolymers are probably largely responsible for the high viscosity of many bark extracts which causes major problems in the use of such extracts as adhesives. There are many such pointers to presence of f 1 avolog 1 yeans in barks as well as leaves of trees and we have begun a major researc h effort - - - - - - - . - - - - 148 at the Wood Chemistry Laboratory to seek such compounds. Our work will concentrate initially on softwood barks of commercial importance. ACKNOWLEDGEMENTS The discovery of the presence and chemical nature of flavologlycans in mangrove leaves was made at James Cook University of North Queensland in collaboration with M.J . Neilson and T.J. Painter as part of a study of diagenesis of the leaves. The detail of the mangrove studies will be published in collaboration with these authors. REFERENCES 1. HASLAM , E. In: J.B. Harborne , T.J. Mabry and H. Mabry (Eds.), The flavonoids , London , Chapman and Hall , 505 559 ( 1975). 2. HASLAM , E. In: J.B. Harborne and T.J. Mabry (Eds.), The flavonoids: advances in research , London , Chapman and Hall , 417 447 (1982) 3. RIBEREAU GAYON , P. Plant polyphenols , Edinburgh , Oliver and Boyd , 176 197 (1972). 4. HARBORNE , J.B. Phytochemical methods , London , Chapman and Hall , 62 (1973). 5 YEAP FOO , L. and PORTER , L.J. Phytochem , 19 , 1747 1754 (1980). 6. MARKHAM , K.R. Phytochem , 11 , 2047 2053 (1972). 7. PULKKINEN , E. and VAISANEN , S. Pap Puu , 64 , 72 75 (1982). 8 . PULKKINEN , E. and PELTONEN , S. Pap Puu , 62 , 687 690 (1980). 9. BAILEY , R.W. and PICKMERE, S.E. Phytochem , 14 , 501 504 (1975). 1 0 . LAVER , M .L., CHEN , C.H., ZERRUDO , J.V. and LAI , Y.C.L • e Phytochem , 13, 1891 1896 (1974). 1 1. ! EMINGWAY , R.W. and McGRAW , G.W. TAPPI Forest Biol , Wood Chem Conf , Madison , 261 269 (1977) - - . - - . - - - - - - - . T H E REACTIONS O F ALKALINE HYDROGEN PEROXIDE WITH 1 , 2-DIARYL-l , 3 “PROPANEDIC LS treatment was performed in the p r e s e n c e o f air or even when the s y s t e m was s p a r g e d with nitro g e n , neither stilbene IV or V was detected the by suggesting that these intermediates are ex - - tremely sensitive t o autoxidation . A.J. NONNI INTERNATIONAL PAPER COMPANY 10987 TUXEDO PARK , NY C.W. DENCE S. U.N.Y. COLLEGE O F ENVIRONMENTAL SCIENCE AND FORESTRY 13210 SYRACUSE , NY ABSTRACT Two 1 , 2-diary 1 -1 , 3 -propanediols were reacted with stabilized and unstabilized alkaline hydro gen p e r o x i le and molecular oxygen under simula ted technical bleaching conditions. Product identification revealed the occurrence o f reac tions in which the n - prcpyl side chain was frag mented a t various locat o n s generating c h r o m o phoric and leucochromop ;oric s y s t e m s potentially capable of influencing brightness in mechanical pulp bleaching s y s t e m s. KEY WORDS: 1 , 2-Diaryl -1 , 3 -PropanedioIs , Alka line Hydrogen Peroxide , O x y g e n INTRODUCTION In a continuation of previous studies ( 1 - 4 ) o f the reactions o f lignin model compounds with alkaline hydrogen peroxide , two propanediols , l -( 3 -e t h o x y-4- hydroxyphenyl )-2-( 4- hydroxy- 3 methoxyphenyl )- l , 3 - propanediol ( I ) and 1 , 2- bis ( 4 - hydroxy- 3 - methoxyphenyl )-1 , 3- propanediol ( II ) were reacted with stabilized ( N a 5 DTPA ) and u n s t a bilized peroxide and molecular oxygen under con ditions simulating those used in technical bleaching. Using a combination of G C , GC/ MS and UV techniques , the principal p r o d u c t s in the reaction mixtures were identified and their yields quantified . Prior t o examining the effect of alkaline peroxide solutions and oxygen on the B- l diols , the effect of alkali alone was assessed. The Effect o f Dilute Alkali on 1 , 2- D i a r y 1 - 1 , 3Propanediols In the absence or near absence o f dissolved oxygen ( i.e. when the treatment was performed in vacuo ), the major effect o f the alkali was t o - c o n v e r t the B l diols t o stilbenes IV and V via a q u i n o n e m e t h i d e ( III ) from B - l diol I as shown Reactions of Stabilized H y d r o g e n Peroxide with B - l Diol ( I ) In this section and in the following sec tions , discussion is restricted t o results per taining t o B - l diol I for the s a k e o f brevity ; the results o f the treatment of B - l diol II with peroxide are similar and a r e reported in detail elsewhere ( 5 ). Under the imposed reaction conditions , - 30 % of 8- 1 diol I was consumed , presumably t h r o u g h conversion t o and s u b s e q u e n t oxidation of stil benes IV and V by peroxide and a small a m o u n t ( 1 - 2 % ) of o x y g e n arising from peroxide d e c o m p o s i t ion. Only trace a m o u n t s of t h e intermediate stilbenes were detected and the main products consisted of ethyl vanillin ( VI ), guaiacylglycol ( VII ), ethanol and methanol ( Table 1 ). The low product yields s u g g e s t that B - l diol I is less reactive toward peroxide than its initial oxida tion products. Based on the t y p e s of products identified , it appears that the main reactions of the 8-1 diol with stabilized hydrogen peroxide ( i.e. where the presence of O 2 is minimized ) involve a nucleophilic attack of OOH “ on q u i n o n e m e t h ide III and the oxidation o f stilbene IV. In the former reaction ethoxyhydroquinone ( VIII ) and guaiacylglycol are postulated as arising via the sequence shown in Figure 1. The transformation giving rise to guaiacylglycol is visualized as the alkaline a n a l o g o f a Baeyer -V 111 iger reac tion ( 6 ). The oxidation o f stilbene TV and V by alka line peroxide in the absence o r n e a r absence of oxygen is rationalized as o c c u r r i n g by a nucleo philic displacement on o x y g e n i n the undissoc 1 a t e d hydrogen peroxide by the stilbene. This c o n c e p t is s u p p o r t e d by the results o f experi m e n t s in which various stilbenes and isoeugenol were reacted with peroxide a t alkalinities cor responding t o the p H range 9 - 13. In such cases the residual stilbene , isoeugenol and peroxide c o n t e n t s w e r e lower at the lower e n d of the pH r a n g e where the fraction of undissociated hydro g e n peroxide was higher ( Table 2 ). in Figure 1 . T h e s e t w o stilbenes , t o g e t h e r with the starting compound , accounted for '95 % of the o r i g i n a l material and o n l y trace a m o u n t s of other products were detected . When the alkaline 149 - Reaction of Non Stabilized Hydrogen Peroxide with 6 1 Diol I ( Fixed pH ) As compared to the situation where a perox ide stabilizer ( Na 5DTPA ) was employed and care was taken to minimize the air ( oxygen ) content in the reaction mixture , omission of the stabili zation system resulted in a substantially higher consumption of 8 1 diol I and in the formation of greater amounts of the oxidation products ethyl vanillin ( VI ), UJ hydroxyacetoguaiacone ( IX ) and ethoxyhydroquinone ( VII ) (Table 1 ). The yields of methanol and ethanol were also substantially increased. These differences are attributed to the more extensive decomposition of peroxide giving rise to oxidants such as C> 2 * OH and 02 . Thus , the electrophilic attack of oxygen on the olefinic group of stilbenes IV and V ( i.e. oxygenation ) and the autoxidation of the 8 1 diol I resulted in the formation of peroxide labile stuctures in addition to those generated by the initial oxidation of quinonemethide III and the stilbenes by 00H" and H 2O 2 , respect ively. . - - - - - - - “ - - - I i ' - Reaction of 6 1 Diol I with Molecular Oxygen The 6 1 diol was reacted with molecular oxy gen in order to identify with greater certainty those reactions and products attributable to this oxidant when it arises from the decomposi ion of hydrogen peroxide. The products and pro duct yields corresponding to this treatment are listed in Table 1 and indicate the major contri bution of ethyl vanillin and the dominance of the methanol content over ethanol content as noteworthy features. Several possible routes can be envisaged to account for the above find ings and it is likely that the overall result stems from a composite of several competing pro cesses in which extensive breakdown of the B ring ( methanol formation ) and splitting of the a , 6 bond ( ethyl vanillin formation ) predominate. - conversion of the diol to a stilbene derivative which then may react with oxygen and /or undis sociated hydrogen peroxide , The latter reactio is important since technical peroxide bleaching is conventionally performed in a pH range where a considerable fraction of the peroxide is undi « sociated. Several of the initially formed products in the reaction of the 8 1 diol with peroxide are either colored or capable of being converted to chromophores through various combinations of autoxidation , oxygenation and other reactions ( e.g • * Dakin and "Dakin like " ). As applied to the peroxide bleaching of mechanical pulps , such reactions could have an adverse effect on bright ness response. However , the potential for 8 1 dilignols in lignin to have such an effect on brightness would require that at least one of the rings in the dilignol be phenolic. - - - - REFERENCES 1. BAILEY , C.W. and DENCE, C.W. Reactions of alkaline hydrogen peroxide with softwood model compounds , spruce mi 1 led -groundwood lignin and spruce groundwood. TAPPI 52( 3 ): 491 500 ( 1969 ). - 2. - - - - - - - - - . OMORI, S. and DENCE, C.W. The reactions of alkaline hydrogen peroxiie with lignin model dimers. Part 2: guaiacylglycerol 8 guaiacyl ether. Wood Sci. Technol. 15 x 113 123 (1981). - - 5. 50 - . - - - - ture. Ph.D. thesis , SUNY College of Environmental Science and Forestry , Syracuse , N.Y. 1982. 6. - NONNI, A.J The reactions of hydrogen per oxide and oxygen with lignin model dimers of the 1 ,2 diary 1 1 ,3 propanediol * • pe struc - - - - 4 - - . 3. OMORI , S. and DENCE, C.W. The reactions of alkaline hydrogen peroxide with lignin model dimers. Part It phenacyl a ar /1 ethers. Wood Sci. Technol. 15:67 79 ( 1981 ). t - KEMPF , A.W. and DENCE, C.W. The reactions of hardwood lignin model compounds with alkaline hydrogen peroxide. TAPPI 58(6 ): 104 108 ( 1975) - - SUMMARY AND CONCLUSIONS *1 The results of the 6tudy reveal that unether lfied 1 ,2 d iary 1 1 ,3 propanediols are oxidized by alkaline hydrogen peroxide and its decomposi tion product , oxygen , in a variety of ways , The initial reactions result in the rupture of the side chain of the 6 1 diol at various sites thereby forminq monomeric phenols having side chains ranging from 0 to 3 carbon atoms in size . One important pathway in the overall se quence consists of the initial alkali mediated - JONES , D.D. and JOHNSON , D.C. The alkaline hydrogen peroxide oxidation of phenyl 2 propanones. J. Orq. Chem. 32: 1402 1409 ( 1967 ). - -- - Functional group Kraft lignin A r o m a t i c r l n g6 1.0 COOH 0 . 1 31 * 0.501 Ketone not found 0.02 Aldehyde 0.03 0.05 Double bond 0.18 0.29 Aliph . CH > 57 ppm A l i p h. CH 2 > 57 ppm A l i p h. CH < 5 6 p p m A l i p h. CH < 5 6 p p m 2 A l i p h. C H ^< 56 ppm per phenylpropane unit 0.56 0.44 0.61 0.34 0.45 0.39 0.25 0.63 0.55 0.18 ) •• 0.19 P h e n o l i c OH 0.792 0.622 ) 0.853 ) 0.584 ) Quart , aromatic C 3.42 3.90 OCH3 ) Conductometric titration acc 2 . t o Ref . 14 ^ Value from Ref . 11 Table 1 Note Oxygen lignin per aromatic ring Assumed value ^ Arainolysis . A n a l y t i c a l d a t a c a l c u l a t e d f r o m * 3C-NMR f o r k r a f t l i g n i n a n d f o r a l i g n i n obtained a f t e r oxygen bleaching t o kappa No . 14.8 1 i t can be seen substantial rings oxygen bleaching leads to a that reduction in the number of remain after substituted bleaching are to a i n t h e 5 and /o r important these is the carbon atoms with shift rnethoxyl group • h e c- u b s t i t u t e d In of below that values •* ••4 ( - by fragmentation bleaching b . These reactions, example, are to a large exrent ( softwood ) rge amounts of left biphenyl unreacted lignin seems alkyl solution 62 . the lignin . The fact fairly groups in the side fragments poor solu in aqueous . . KRATZL, K . - - . . , G R A T Z L , J a n d CLAUS , P Formation and degradation of biphenyl structures during alkaline oxidation of phenoU with oxygen A d v Chem Ser 5 9 : 157 176 ( 1 9 6 6 ) . . C I E R E R , J . a n d I M S G A R D , F ; C H A N G , H-m a n d GRATZL J . ; A O Y A C I , T. , HOSOYA , S . a n d . .V. , . NAKANO J ; ERICSSON , B , SARKANrN , K and TIEDEMAN, T i n Chem1s t r y o f d e l l g n l f l c a t l o n w i t h o x y g e n , ozone a n d Peroxides Uni Publishers Co, Ltd , Tokyo, J a p a n 1980: 137 1 5 0; 151 1 6 3; 1 6 5 171; . . - - structures to contain chains may further contribute t o a bility of . take reactions also balanced by a certain selectivity in the lignin •hat t h e NMR to 0LM , L and TEDER, A The kinetics of oxygen bleaching T a p p l 6 2 ( 1 2 ) : 43 46 ( 1979) - Indicating facilitating lignin dissolution, are counter for for generous access . . . large amount of carboxyl groups seem to be formed , oxidition and , 1 t ies REFERLXCES the aromatic rings. In addition, new phenolic place during Grenoble in pulps, a kraft t lignin dissolution 16 achieved lignin - in collaboration with Dr are also due to the Magnetic Resonance Center 1 . groups mainly through oxidative cleavage of that " . D. R o b e r t , C e n t r e , d ' Etudes Nucl£a l r e s d e Grenoble. Thanks 2 a the oxygen bleaching of hydroxyl -8 5 a n d b y t h e N a t i o n a l . Such carbon atoms are to modify by chemical reactions *i t * : J. • 1 r • Introduction of a by h a v e been s u p p o r t e d . - faci functional groups which are CONCLUSIONS partial aliphitic only with hydrogens and carbons and thus constitute difficult from . Another high number of "SSVL f o r Technical Development , g r a n t No 8 4 3 3 5 8 . 1 3C N M R a n a l y s e s h a v e b e e n c a r r i e d out feature concerning the structure of lignins this work Board the 6 posltlon(s) the oxidative degradation analysis Parts of financially large extent thus supporting the results obtained ACKNOWLEDGEMENTS aromatic . Furthermore, the aromatic rings which -_ 173 187 c• - - - - . . HOLOCHER ERTL , M , FK 1CK 0 , P and KRATZL, Oxygen oxidation of lignins. K. I n t e r n a t i o n a l S y m p o s i u m o n Wood a n d Pulping Chemistry Stockholm , June 9 12 , 1 9 8 1 : P r o c e e d i n g s V o l 2 , 83 89 . - - Table 1. Oxygen Products from the Reaction of 8-1 Diol I with Hydrogen Peroxide and Yield , Mole % H 9O 9 Ui,stabili zedb H 9O 9 Stabiliz eda Compound Ethoxy 8-1 Diol , I 70 Stilbene , IV Stilbene , V Ethyl vanillin , VI Ethyl vanillic acid or hydroxyl substitu ted ethyl vanillin co -Hydrox - acetoguai acone IX Guaiacyl glycol, VII Ethoxyhy droquino ne , VIII . Methoxyh ydroquin one 1 , 2 , 4 -Trihydrox ybenzene 16 - j 3- 4 6 -7 ( Tra :e ) *A 2 (Trace ) \ Oxvgenc 31 14 -18 15 4 60 2 ( Trace ) 7-8 4 15 v^ ( Trace ) / * - 3 4 17 29 4- 5 • Ethanol • v I 36 15 Methanol i ./ Reaction Conditio ns: " a l H 2021 / 1 8-1 diol ) = 3, [ 8 -1 diol ) = 0.07 x 10 “ 3 , [ DTPA ) = 0.4 x 10 3, ( MgS04 ) = 0.16 x 10"3, 45°C, 4 h , pH 10.5 , in vacuo. bas in "a " except DTPA and MgS04 were omitted and reaction was performed under N 2 coxygen added continuou sly for 4 h at 45°C and pH 10.5 7 < .• * Table 2. 3 Reactivit y of a , 8-Unsatura ted Phenols with Alkaline Hydrogen Peroxide Initial Compound pH Atmospher e Residual H 2O 2 % of Applied Residual Phenol % of Applied 97 99 -100 in -vacuo 9.0 98 97 100 in -vacuo 10.5 trans -Stilbene 85 78 in -vacuo 9.1 p -Methoxyst ilbene 96 -97 87 90 in -vacuo 10.5 p -Methoxyst ilbene 76 86 in -vacuo 10.5 4 , 4 * -Dihydroxy stilbene 96 96 nitrogen 13.0 4 , 4 * -Dihydroxy stilbene 65 74 in -vacuo 9.0 4 , 4'-Dihydroxy stilbene 83 82 nitrogen 10.5 Isoeugeno l ; 96 90 nitroqen 13 Isoeugeno l 3 3 ”3 aReactio n conditio ns: ( model ) = 5.89 xl 0 ; [ H 2O 2 )/( DTPA 1 = 0.40 x 10 ; [ MgS04 ) = 0.17 x 10 ; trans -Stilbene - - “ “ 45°C, 2 h 15 Y CHpOH I $ HO — 8 ) ) OH I a HCOH OCH3 OH- I CH 2OH HC C =0 I OCH 3 I HC OCH3 HCHO JK HC U I CHO HC OH OOH ~ t 0 COOH OH OC2 H5 OH 3Z2T OH OH + CH2OH ° 2 CHpOH I I HC OH OCH3 * ' HCOn OC2H5 CH2OH CHpOH CHO COOH I + OH OCH3 o ^ 'OCH, 0 H ' HGURE I OUTLINE OF PRIMARY REACTIONS IN TREATMENT OF P H DIOLl WITH ALKALINE HYDROGEN PEROXIDE 152 * same method(dEi) to be 1.34%• > which is 70% less than that of wheat straw MWL. This is probably one of the major causes for wheat straw lignin to be easily removed in alkali. CHARACTERIZATION OF WHEAT STRAW LIGNIN ZHONC ZHENG LEE AND XI 0 QI PAN OCH3 total Zeisel 1 H NMR - DEPARTMENT OF CHEMISTRY <& ENGINEERING OF FOREST PRODUCTS NANJING INSTITUTE OF FORESTRY NANJING , CHINA - Acetylation 1 H NMR 16.87% 1.09/C9 I.IO/C9 11.23% 1.33/C9 OH phenolic OH - 1H NMR A Ei 2.25% 1.35/Cq 0.27/C90.34/C(> Table 2.Functional groups of wheat straw MWL ABSTRACT Milled wood lignin(MWL) isolated from wheat straw was characterized by means of GPC , nitroben zene oxidation ,functiona 1 groups and other chemi cal analyses , as well as spectral studies inclu ding UV , IR , 1H NMR and 13C NMR . As compared with birch MWL , wheat straw MWL is richer in guaiacyl and has more phenolic hydroxyl content. Also wheat straw MWL h is a molecular weight much lower than birch MWL. - - - - - KEYWORDS: Wheat straw , Milled wood lignin(MWL). INTRODUCTION Wheat straw is one of the most major grass materials of paper industry in China. The studies on the pulping mechanism of wheat straw showed that about 60% of the lignin were removed in alkali prior to 100°C , which is much different from wood(l). This difference is probably due to that wheat straw lignin differs from wood lignins in their nature and distribution in cell wall. This paper concerns studies on MWL isolated from wheat straw by chemical and physical methods , in order to well understand the characteristics and relation with its behavior during pulping. RESULTS AND DISCUSSION i * Elemental analyses and functional groups Sample % C Wheat straw MWL 60.81 Birch MWL % H % 0 5.42 33.60 0.17 16.87 57.77 6.09 34.05 % N - 2 Molecular weight and molecular weight distribution % 0CH 3 20.13 Sample Mn Mw Mw / Mn Wheat straw MWL 2 ,953 8 ,854 3.0 7 ,322 18 ,1 n 2.5 Birch MWL Table 3.Average molecular weight It is notable that the average molecular weight of wheat straw MWL is seen to be about one half as much as of that of birch MWL. This may be consi dered as one of the major causes for wheat straw lignin to be easily removed during pulping. - - 3. Ester linkage of wheat straw MWL Wheat straw MWL was treated with NaOH solution and its alkaline hydrolysis products were deter mined by HPLC. The most major product was p cou maric acid and small amount of ferulic acid was found. The amount of p coumaric acid was 2.08% ( based on MWL), whereas the amount of ferulic acid was about one twentieth of that of p coumaric acid The HPLC also showed the presence of traces of p hydroxybenzoic , vanillic and syringic acid. The ester linkage is easily saponified in alka li , therefore this portion of the lignin is easily removed during pulping. - - - - - - - 4. Alkaline nitrobenzene oxidation Sample % V % S % H V :S : H Wheat straw MWL 14.58 13.59 3.95 1 0.77 0.31 14.96 15. 11 2.28 1 0.84 0.18 9.24 1 1.49 Saponified MWL Birch MWL 16.44 Table 4. Nitrobenzene oxidation products Table 1. Elemental composition The C9 formulas calculated from Table 1 were ,, 9 7.39 3.0 OCH3 1.09 and C9H8.70 2.95* OCH3 1 .55 ° ^ ^ birch MWL ,respective ° 1y. ^ for wheat straw and C Especially noteworthy is the large difference tn the phenolic hydroxyl content . The phenolic bydroxyl content of birch MWL was estimated bv As shown in Table 4 , it is obvious that wheat straw lignin is richer in guaiacyl than birch lignin. On the other hand , the amount of p hydro xybenzaidehyde of saponified wheat straw MWL was 58% of that of unsaponified MWL. This means that this portion of p hydroxypheny 1 is linked via other chemical bonds to the lignin , possibly - - - 153 phenol ether linkages. In the aliphatii region(50 90 ppm), occur three 5. Ultraviolet spectra Wheat straw MWL gave an absorption at 280 nm 1 nd its absorption coefficient was 20.4 l gVcm > oth similar to softwood lignins. These results are consistent with that wheat straw MWL has a relatively high amount of guaiacyl and some p hydroxypheny 1 units as compared with birch MWL. Also wheat straw MWL gave a shoulder around at 315 nm and after treated with NaOH solution , this peak was almost completely dissappeared indicating that this absorption is duo to the presence of p coumaric acid esterified to the lignin. strong signals !r ,22 and 25 , which can be assi gned to carboL floras /3 f ot and r in /3 0 4 struc tures ,respec t ivel.. Also other 1 inkages ,such as - _ l - - - -- - * f?- l , ft - 5 ,were fc nd in the spectra. / ^ n - 6. Infrared spectra » .\ n n 7» ,,, I Strw MWt 700 ^ V" ' .. IV 100 SO ppm . C Figure 2. 13. KF spectra of wheat straw MWL -* CONCLUSION VMioat straw MWL (sapomf**d) The characteristics of wheat straw lignin can be summarized as follows: 1. WTieat straw linin is distinguished as GSH lignins and rich in guaiacyl. 2. The phenolic hydroxyl of wheat straw lignin is more than that of birch lignin. 3. Wheat straw lignin has a molecular weight much lower than birch lignin. Birch MWL EXPERIMENTAL 1500 » 000 - CM 1 Figure 1. Infrared spectra of wheat straw MWL As seen in Figure 1 , the apparent difference among these three MWLs is the bands at 1715 and 1170 cm 1 , which are responsible for the absorp tion of ester linkage. These absorption were not found in birch MWL , however almost completely dissappeared in wheat straw MWL treated with NaOH solution indicating the ester linkages were saponified . The relatively weak absorption inten sity of 1715 and 1170 cm 1 also showed that the amount of ester likage of wheat straw MWL is small. - - - - C. NMR spectra basis of Nimz ’ s studies(2), in the aromatic region( l 04 160ppm) of the spectra the “ ( W' ngy 1 S) and tuaiacyl(C) residues are indicated .gnals 4 ,9 P S) and 5 ,6 ,7 ,8 , 11 , 14 t 15(G). The signals 12 , 13 , 16 caused by p hydroxs nheny 1(H) can » e taken as character ic signals lor GSH lignin . * — . 54 - - - - - - - -reference TMS. ^ ^ : REFERENCES 1. LEE, .Z. Studies on the Digestion of Straws. Comparision of Reaction Behavior of Different Pulping Methods for Wheat straws. China pulp and paper 2(3): 21 29 (1983) 2. NIMZ , H.H et al Carbon 13 NMR Spectra of Lignins 8. Structural Differences between Lignins of Hardwoods ,Softwoods ,Grasses and Compression Wood. Hoizforschung 35(1) : 16 26 (1981) 3. BJ0RKMAN , A. Studies on Finely Divided Wood Part 1. Ixtraction of Lignin w i t h Neutral Sol vents. Svensk Papperstidn 59( 13):477 *85(195 b) . On the it • Wheat straw MVL were prepared by the procedure of Bjorkman(3). Sephadex LH 60 with 0.1 M LiCl in DMF and Waters /A styragel with THF were used for deter mination of molecular weight distribution. 13C NMR spectra were measured by a Varian FT 80 A NMR spectrometer , solven t: CD COCD and - - - - - - rotting by wuite roc In view of these A N E L E C T R O N .M I C R O S C O P E S T U D Y O F A T T A C K O N S T R A W BY PANUS CONCHATUS H U I SItENG Y U , Y U Z H U X I N G , W E I-L I W A N G A N D YONG JUAN TAO - - patterns and . AUNGI h a s i acts , ' been reported the fungal growth the microinorphological changes m s t r a w froiii t h e f u n g a l a t t a c k h a v e b e e n i n v e s t i gated the presen in work - using scanning eiectr « •i.i c r o s c o p y. RCSUl fo . TIANJIN PULP AND PAPER RESEARCH INSTITUTE 1 5 T I A N W E I R O A O, TIANJIN, CHINA Changes ABS fit A C r - U s i n g the w h i t e r o t f u n g u s P a n u s c o n c h a c u s, the growth pattern of the fungus and the changes in micros trueture of straws through m tissue construction Hie micrograph has clearly shown that pnren chyma which mainly exist around the vascular progressive b u n J l e s a r e l i r s t a t t a c k e d o n, d e c o m p o s e d i n fractions, and then disappear in early decay . 1 ). I n a d v a n c e d d e c a y , d i e m i d d l e iuiiielJ ( Fig between libers is completely decomposed , l ibers degradation have been investigated by the aid - e i tiier in tiie vascular bundles or epidermis o f e l e c t r o n m i c r o s c o p y. I t h a s b e e n s h o w n t h a t parenchyma are first attacked and destroyeu cell layer inward are individually separated and r a p i d l y. T h e n , t h e m i d d l e l a m e l l a b e t w e e n f i b e r s are always predominant is c o m p l e t e l y d e c o m p o s e d, t h e l i b e r s a r e i n d i - tiie s e p a r a t i o n o 1 the fiber closing to parenchym . The epidermis are parti- cularly resistant to degrade oven tnough vidually separated, and the secondary wall e x p o s e s a m a c r o f l b r l1l a r s t r u c t u r e i n d i c a t i n g tissue construction has that lignin is removed and a cellulose frane vork is - . The gradual thinning of se ouaary left w a l l o f f i b e r f r o m l u m e n, t h a t i s n o r m a l p a t t e r n of » ood - rotting by white rot fungi, has gene rally not been observed in . These straw rotting results further indicate that P considerable potential lor - . concha tus uas biopulping and other in . 2 ). S i m i l a r p a t t e r n o f ( fig advanced decay a l s o b e e n o b t a i n e d I r o n, . decomposed wheat straw and reed Hypnae distribution fiio a t t a c k o f n y p h a e o n s t r a w n o t o n l y s t a r t s l r o m the e n d s o f s t r a w s t i c k s, but a l s o o c c u r s o n s t r a w s u r f a c e. T h e n , t h e h y p h a e g a t h e r a t t h e Fiu.3 ). S i u i u l t a n - lununa of parenchyma cells ( ously, hyphae also attack on fibers and penetrat ( F i g. 4 ). T h e d e l i ^ n i f i c a t i o n p r o c e s s e s o f s t r a w , I n a d d i t i o n, it has been found that epidermis colls of straw into the lumma of the libers a r e p a r t i c u l a r l y r e s i s t a n t t o d e g r a d e a n d tiie d e t a c h m e n t a l o n g SJ /SJ a n d S.2 / S 3 t r a n s i t i o n naturally existing connections such as pits and . hypnae propagate and spread mainly utilizing . The spread of hyphae through boring stimaca holes on the wall of parenchyma ceil or liber layers occurs K E Y .« U P U S: W h i t e r o t f u n g u s , S t r a w r o t t i n g , Electron microscopy, Lignin bio degradation - . - and through the area of middle lamella layer beeween libers has also been observed ( r i g. 5 ) Mi croinorphol ogi ca 1 changes In incipient decay it has been found that the JLN m o u u c r i O N P a n u s c o n c h a t u s i s t h e w h i t e -r o t f u n g u s w i n c h can cause very efficient rotting of both wood and straw iv . It has been demostrated that 1ason lignin in rice straw could be degraded . b y t i i s f u n g u s f o x’ 2 0 d a y i n c u b a t i o n , a n d b i ological pulp with good strength properties was p r o d u c e d a l t e r d e f i b e r i n g ( d u l l. P u l p . I n s t. h es Paper C h i n e s e L i g h t I n d. M i n i s t r y , i j l J )• components S l -l a y e r a n d m i d d l e l a m e l l a t a k e p l a c e w i t h C h e f u r t h e r d e g r a d a t i o n b y tiie f u n g a l a t t a c k , s o tiiat l i b e r s c a n b e e a s i l y s e p a r a t e d f r o m o n e . 6 ). A n m c r o l l b i l l l a r s t r u c t u r e a p p e a r o n t h e c e l l w a l l ( F i g. b ). i t m e a n s t h a ’ another ( lignin is tant this iungus has considerable p o t e n t i a l lor A l a r.i G n u m b e r o l d a t a a r e a v i l a b l e c o n c e r n i n g tiie m i c r o m o r p h o 1 o g i c a l c h a n g e s d u x i n0 W O O d - - ( 2 4 , 6- 7 ) • and a cellulose lramwork tiU t l i m i t e d i n f o r m a t i o n r e l a t i n g t o tiie s t r a w is 3 /S j t r a n s i t i o n l a y e r s h a v e a l s o b e e n ^ o b s e r v e d ( F i g. 7 ) S j l a y e r s e e m s t o b e r e s i s - . to degrade til i n n i f l g u l by - . Hie gradual the fungus secondary wall has generally not beer 1 ound intao rotting of rice straw even . de 1ignificatlon processes decay by white rot lungi removed . I n a d d i t i o n , tiie d o tacliiiion t s a l o n g concha tus in thiee days following i n o c u l a t i o n ( 1 )• These r e s u l t s i n d i c a t e d tiiat ^ Fig left and suxaw by P - -layer o f f i b e r s a r e d e g r a d e d a n d tiie d e t a c h m e n t b e t ^ e e i i o c e n t r e s u l t s o b t a i n e d s h o w e d t h a t 2 4 . 7> w a t e r soluble modified lignin released iro n wheat . between middle lamella and 3 tiie f i b e r s a r e decay individualiy u y P. c o n c l i a i.u a separated chough i n a d v a n c e *, ( F i g. b ). U l S C U -j j i O N Hie r e s u l t s obtained have oltnrotl knowledge ol a bn i ter t h e f u n g a l O r o w t h p a t t e r n a n d tiie nilcromorphological changes in decomposed straw 155 . from the attack by Panus conchatus Compared with the pattern of wood degradation - by white rot 1 ungi that have been reported , The following similarities and differences are poin - ted out: similarities The fungal hyphae spread through pits and other openings of ceil wall and penetrate into the 1 umina of parenchyma cells and fibers ( 3 ) • The spead of hyphae produces bore holes on the - -are - S. cell wall ( 3 » 7 )• The attack on the libers closing to parenchyma i)i l 1 . always predominat ( 4 ) erences — J t has been reported that white rot fungi ol t ii cause a giadual thinning ol the wood cell wai 1 , starting from the lumen continuing towards ^ lamella (j,6 ,7) and only cell c o i n e r die aiiudle with a little secondary wall i s left i n advanced decay ( 7). The middle lamella is resistant to i n lotting sweetLun i s earlier destroyed than ray parenchyma cells are (7), In contrast , a selective degradation of lignin in These observations mean that decomposition rot tin0 of lice straw R .FFKgNC.JS ! • Yu , H S. ANb - . conc.ia tus. by P ^RIKS^ON., 1A- 53£. to be submitted l to Svensk Papperstidn * . A. Can. J .^ Dot. 3b: l 4 -l ;>u3 . ML ANCIig T V L, , R ( 1 «U ) 2 ^ yb -. . K 3 , GrU.NbWALD , A . , NlL bUA , T ^ A.Mb VALLA Jdi*;:., L. hoi zl or s c riun j4 (o) : ^ *£K 1 UbSCN , - 207 213 ( lyoo ) k. RUi L , K., BAix IS OUL), F • A \ d £Li..SJdN , K - g Molzforschun;; 33(4 ) 2157 -1 71 ( l > b l ) 3• 1 An11 , Y • f S U& , A • a N O \ A Ma J b C111 , A • J. £1 ec tronmi croscopy 17: & k ( l ob ) b. oCil lil), P. , LlbsL , k . Arcli. Mikiobiol. 47: 2 ou- «.7 b ( li> 04 ) W1LC0A , u • u . Changes i n wood imcrostrue cure 7. . ^ . ^ . through p r o g r e s s i v e stages ol decay Torost berv , . Paper PPL 7b , Foiest lies Products Laboratory , Madison , straw lotting by . U. S. . ( 1 68 ) *» l s ^ P. conchatus. The middle lamella between libers Figure legends completely decomposed and the intact fibers is .1 can easily be separated lrom one another ( Fig 2 ) The appearance of the macrofiori 11 ar stru Fig ctuie on the secondary wall indicates that lignin Fig . . - * is removed leaving a cellulose framework .2 . Straw t • parenchyma are decomposed and disappear rapidly early decay ( Fig * 1 Di ). Tne results ootained have also offered a ten that most of lignin in rice straw could be deg - ith O - . J Lon itujinal section , r i c e straw , 13 days , . - .k Fig Tiansveise section , rice straw , 1 j days , Jlyphae penetrate the lumina ol . M = b80 fibers . is .3 Fig Lhe * Longitudinal section , r i c e straw , 2 k days , The spread ol a hyptia through rapidly decomposed and fibers could is - chyma cell Hie middle lamella where the lignin conten higher 0 The hyphae ‘0ather at a lumen of paren produced by P - - in .. dividually separated and the epider. i s are particularly resista.it to degrade Fig ood strength properties could be . cone ha tus. That is : Lice straw , 24 uays , The fibers are . r.ideu lor limited time incubation ana biological pulp Transveise section , rice straw , ? days , The parenchyma are Jecon.posed. 1 = 220 'h= 3J0 xpianation in connection with the facts taLive should occur at large distances lrom hyphae and a highly dill usable lignin enzyme system exist during the * abrade ( k ). The secondary wall of most fibers has been observed . almost all fibers are nidiv 1 uual 1 y separated 3. layers are resistant to degrade (4) « and s crates tnat cho fungal hyphae are not observed i n all libers and an > part ol cell wall , but . area easily be separated ol middio lamella and a boring nole on - the fiber wall thinning of cell wall occurs wtien \o obvious uhe libeis are separated , ol ry ted libers can \> e decomposed course , the sena in highly advan - - .6 Fig . M = 220u Longitudinal section , rice straw , 24 . , days Middio lamella a re decomposed and . If suitable control is carried out , . uaci of l bi 11 I a r ced decay a tne libers with limited damn e can be obtained. the cell wall. .’ = 2400 - ironchyina colls are dostioyed oi is lice in early decay . The nisappeaianco of these calls straw oeneficiul to improve t « u strength properties po p and dewatering i n the papermaking . • process . - loose tissue c traw . cone by P » j c iiinu 0 * .55 Transverse section , rice a trow , 15 days , It snows the d o tac ni».t» n t s « 1 ong and .6 Fig Sx / 3 Transition layer. M =8J00 ^ Uice straw , 24 days , No obvious thinning occur on the degree are also ; .7 Fig structure appear on IS true tion and low lignilied HJtoiicinl to the attack on rice . IIUB election microscopy clearly deroo - iher w a l l s even . M = 1700 t 'Ouuli cho libers arc separ. ted . Fig 1 i 003188 20KU I X80*2 I F i g. 3 Fig .4 I fi 157 086997 20 KU 067* 2 NH .* * « » #• • <, • • . •• » % / I 03920 20KU 010*2NH Hg. 7 158 •» 087309 20KU 088*2NH Fig. 8 entered at a 57 ppm A l l p h. CH2 > 5 7 p p m A l i p h. CH < 5 6 p p m 0.34 0.45 0.39 0.25 A l i p h . CH2 0.63 0.55 0.18 0.19 0 . 7 92 ) 0.853 ) 0.584 ) Aliph Aliph < 56 ppm . CH3 < 5 6 ppm O C H3 P h e n o l i c OH 0.622 Quart , aromatic C 3.42 ^ ) •• per aromatic ring 3.90 Conductometric t i t r a t i o n acc. to Ref 2 ) Value from Ref 11 . 14 . Table 1 Note Oxygen lignin Kraft lignin Assumed value Aminolysis . A n a l y t i c a l d a t a c a l c u l a t e d f r o m 1 3C- N M R f o r k r a f t l i g n i n a n d f o r a l i g n i n o b t a i n e d a f t e r oxygen b l e a c h i n g t o kappa No. 1 4 . 8 < •• can be seen it substantial rings ' that oxygen bleaching leads to a remain after bleaching are to a large extent substituted i n t h e 5 and /o r the oxidative degradation analysis * raethoxyl group he Mjhst 1 lured ' hus aliphatic v a l u e s below t h a t to modify by chemical reactions r In the oxygen partial * i» - i * * i 11 » '» » * r bleaching of kraft lignin dissolution bleaching is achieved large extent a rge amounts of 162 . ities . 2 a• P and CLAUS KRATZL, K , GRATZL, J Formation and degradation of biphenyl structures during alkaline oxidation of phenols with oxygen A d v Chen Ser 5 9 : 157 176 ( 1 9 6 6 ) by the left unreacted lignin seems alkyl biphenyl b structures . The fact to contain fairly groups in the side c h a i n s m a y f u r t h e r c o n t r i b u t e t o a poor s o l u b i l i t y of the lignin fragments In aqueous solution . Thanks f o r g e n e r o u s a c c e s s t o t h e NMR . . - . . . . . GIERER , J a n d I M S G A R D , F ; C H A N G , H-m a n d GRATZL J . ; A0YAG 1 , T . , HOSOYA , S . a n d NAKANO, J ; ERICSSON , B , SAR KANr N , K V a n d T I LDEMAN , T in Chemlst ry of dellgnlflcatlon with oxygen, ozone and Peroxides Uni Publishers Co, Ltd , Tokyo, J a p a n 1 9 8 0 : 1 3 7 1 5 0; 1 5 1 1 6 3; 1 6 5 1 7 1; - 173 187 . - . - . c . . . . These r e a c t i o n s , for example, ( softwood ) N u c l £a i r e6 d e G r e n o b l e and TEDER, A 0LM , L The kinetics of oxygen bleaching Tappl 62( 12 ) : 4 3 4 6 ( 1979) - to . D. R o b e r t , . p u l p6 , a facilitating lignin dissolution, are counter balanced by a certain selectivity in the lignin are the N a t i o n a l REh ERLNCES h y d r o x y l g r o u p s seem t o be f o r m e d , i n d i c a t i n g that lignin fragmentation reactions also take ’hat by . - in Grenoble •* . In addition, new phenolic oxidition and , and are also due to the Magnetic Resonance Center 1 . groups mainly through oxidative cleavage of place during ** in collaboration with Dr introduction of a large amount of carboxyl aromatic rings -8 5 . Such carbon atoms are only with hydrogens and carbons and CONCLUSIONS . - faci of constitute functional groups which are difficult "SSVL Centre, d 'Etudes feature concerning the structure of iarbon atoms with shift t h i s w o r k h a v e been s u p p o r t e d by Board for Technical Development , g r a n t No 1 3C N M R a n a l y s e s h a v e been c a r r i e d 84 3358 out from . Another lignins i s the high number of these Parts of financially the 6 posltlon(s) thus supporting the results obtained Important ACKNOWLEDGEMENTS reduction in the number of aromatic . Furthermore, the aromatic rings which -- - . . - . . - - . . and KRATZL, HOLOCHER E R T L , M , FR 1CK 0 , P K Oxygen oxidation of lignins I n t e r n a t i o n a l S y m p o s i u m o n Wood a n d Pulping Chemistry Stockholm , June 9 12 , 1 9 8 1 : P r o c e e d i n g s V o l 2 , 83 89 . . - . - 3 a. - CIERER , J ., PETTERSSON , I. and SZABO LIN , L i g n i n c h r o m o p h o r e s . P a r t 2. T h e I. behaviour of 2 , A ' and 4 ,4 ' dihydroxy stilbene s t r u c t u r e s t o w a r d s o x y g e n a l k a l i . A c t a Chern Scand B 2 8 : 1129 1135 (1974) - - - - - b. GIERER , J ., IMSGARD , F . a n d NOREN , I . S t u d i e s o n the d e g r a d a t i o n of p h e n o l i c l i g n i n u n i t s of the 0 a r y l e t h e r t y p e w i t h oxygen i n a l k a l i n e m e d i a . A c t a C h e m Scand B 3 1 : 56 1 57 2 ( 1 9 7 7 ) - - 4. GIERER , J . C h e m i c a l a s p e c t s of k r a f t p u l p i n g . W o o d S c i T e c h n o l 14 : 2 4 1 266 ( 1 9 8 0) 5. GELLERSTEDT , G . and LINDFORS , E. L. Structural c h a n g e s i n l i g n i n d u r i n g kraft c o o k i n g. Part 4. P h e n o l i c h y d r o x y l groups in wood and kraft p u l p s. Sven s k P a p p e r s t l d n 8 7( 1 5): R 115 R U 8 ( 1984) - - 6. G E L L E R S T E D T , G . , L I N D F O R S , E.L., LAP IE R RE , C. and MONTIES , B. Structural c h a n g e s in lignin d u r i n g kraft c o o k i n g . Part 2. C h a r a c t e r i z a t i o n by a c i d o l y s i s . S v e n s k P a p p e r s t l d n 8 7(9): R 6 1 R 6 7 ( 1984) - 7. G E L L E R S T E D T , G . and GUSTAFSSON , K . published 8. K U A N G , S.J., SARA , S. a n d GORING , D . A.I. T h e distribution o f c h l o r i n e i n c h l o r i n a t e d kraft pulp f i b e r s f r o m s p r u c e wood a s d e t e r m i n e d by T F. M EDXA . J Wood C h e m Technol 4 : 163 169 ( 1 9 8 4) - - 9. t o be G E L L E R S T E D T , G . and LINDFORS , E.L. S t r u c t u r a l c h a n g e s in l i g n i n d u r i n g k r a f t p u l p i n g. Holzforschung 38 : 151 1 5 8 ( 1 9 8 4) - 1 0. VIERHAPPER , F.W., T E N G L E R , E. and KRATZL , K . Zur S a u e r s t o f f o x i d a t l o n v o n K r e o s o l d e r i v a t e n i n alkalisch w a s s r i g e r Los u n g . M o n a 1 8 h Chem 1 0 6: 1 191 1201 (1 9 7 5) -- 1 l. R O B E R T , D. R ., BARDET , M. , G E L L E R S T E D T , C a n d LINDFORS , E.L Structural c h a n g e s i n . . l i g n i n d u r i n g k r a f t c o o k i n g . Part 3. O n the s t r u c t u r e o f d i s s o l v e d l i g n i n s. J Wood C h e m T e c h n o l 4 : 2 3 9 263 ( 1 9 8 4 ) - 12 . FAVIS , B.D. , YEAN , W.Q. a n d GORING , D. A . I. M o l e c u l a r w e i g h t o f lignin f r a c t i o n s leached from unbleached kraft pulp fibers. J W o o d C h e m T e c h n o l 4 : 31 3 3 2 0 ( 198 ) - ^ 13. R O B E R T , D., GELLERSTEDT , G . and BARDET , M. t o be p u b l i s h e d 1 4. KATZ , S., BEATSON , R . P. a n d SCALLAN , A.M. T h e d e t e r m i n a t i o n o f s t r o n g and w e a k a c i d i c g r o u p s i n s u l f i t e pulps. S v e n s k P a p p e r s t l d n 8 7(6): R 4 8 R 5 3 ( 1 9 8 4 ) - ! were synthesized and are shown in Figure 1. xn ( the case of GG II , SG II and SS II , the three steroisomers were used. Method of treatments: The model compounds were dissolved (5m mol /1 ) in the soda vOH , 0.1 mol / 1 ) and kraft cooking liquor (OH 0.1 mol / 1 . SH 0.015 mol / 1 ) in an atmosphere of nitrogen. The substrat \ solution was treated at 4 temperatures ranging from 110 *C to 140 *C. The course of the reactions was followed by taking about 10 samples over a period which covered at least two thirds of the total reaction time after the desired temperature had been reached in 5 minutes. i Method of analysis: After cooling the sampl * to room temperature , an aliquot (3.0 ml ) was - ON THE REACTION OF SOFTWOOD TYPE .ND HARDWOOD TYPE LIGNIN MCLEL COMPOUNDS ? V.ING ALKALINE PULPING - - RYUICHIRO KONDO. YUJI TSUTSUMI AND HIROYUKI IMAMURA . - FACULTY OF AGRICULTURE , 46 08 KYUSHU UNIVERSITY FUKUOKA . 812 JAPAN ABSTRACT In order to investigate the effect of funda - - mental lignin structures on the cleavage of B aryl ether linkages during alkaline pulping , softwood and hardwood lignin model compounds were synthe sized and treated under soda and kraft pulping conditions. The cleavage of B aryl ether linkages was analyse! kinetically and the comparison of the reaction of softwood lignin and hardwood lignin i was discussed. - - KEYWORDS: Alkaline Pulping , Lignin model compound , Kinetics. INTRODUCTION It is well known that hardwoods are pulped more easily than softwoods due Doth to the different chemical nature of the two lignins and the lower lignin content of hardwoods. Hardwood lignins differ from conifer lignin by the presence of withdrawn and transferred into a 10 ml volumetric flask , followed by the addition of 0.5 M phosphate - buffer (PH = 3) 2.0 ml and 4 methylguaiacol acetonitrile solution 5 ml a: an internal standard An aliquot (5 ) of the reaction products solution was injected directly into HPLC to determine the amounts of the starting materials and the 8 0 4 cleavage products such as guaiacol and 4 methyl syringol quantitatively. The areas of the peak were measured by means of a computing integrator i and converted into amounts using calibration cures which in all cases were linear. The amounts of substrate and products are expressed in the figures in mole % of the theoretical . The reactions were studied under pseudo first order conditions using i excess of [OH ]and [SH~]over [substrate . JAI - - syringylpropane in addition to guaiacylpropane units. Fergus and Goring observed the topochemical removal of lignins from the fibres and vessels in birch woodland spruce wood ^by sulfate and sulfite pulping with UV microscopy . In these pulping processes , the syringy 1 1 ignifled fibres generally - - - - - ] - concentration of starting material , and a refers - to the theoretical and x to the actual concen tration of the product formed. - - woods did not depend on the accessibility of the - - Integration of the rate equation gives the expressions In b and In a/a x where b refers to pulped faster than the guaiacy 1 1 ignified vessels. They concluded that the rate of de 1 ignification in lignin but rather on the chemical structure of the lignin gel in woods , However , to what extent this difference may be attributed to the de 1 igniflcation of softwoeds and hardwoods has not yet been demon strated. In this study , in order to investigate the effect of the difference of principal chemical structures between softwood and hardwood lignin on the delignification rate of these woods , the typical softwood and hardwood lignin model compounds were synthesized and treated under alkaline pulping conditions. The results were analysed based on studies of the kinetics of the reactions involved. -- - GG I : Ri = R * = R » = R % H GG II: R ,sCH,0H , R 3 = Ri = R » H SG I : Ri = R , = R % = H , R ,=0CH , SG II: R , = CH ,OH , R ,=OCH I • Ri = R * = H SS I : R , = H R ,= R ,=0CH » • R * =CH , SS II: Ri =CH j OH , R ,= R , =0CH i • R * = CH * - - —— H C O i HO — C — H t « - OCH3 - . - Fig.l. Model compounds EXPERIMENTAL Materials: Six kinds of B -0- 4 model compounds 165 Six compounds were treated with soda and white liquor. The reactions were followed by a decrease \ in the amount of starting compounds and the \ increase in the amounts of the ether cleavege products such as guaiacol and 4 methylsyringol. 0.5 Some parts of the results are illusrated in Figures 2 and 3. Figure 2 shows the plots for a pseudo first order reaction of the cleavage of JO GG I , SG I and SS I by white liquor at 120 *C. All c reactions followed a pseudo first order reaction 1.0 and the rate of cleavage reaction is in the order - - - - - - - - - - SS - 1 Kraft - 120 C ° ^ \ - - - - 100 - of SS I> SG I > GG I. Figure 3 shows the reaction of GG II , SG I 1 and SS II as a function of time for the treatment with soda liquor at 120 *C. The reaction of GG II and SG II followed pseudo first order reactions. However , it is immediately obvious that the reaction of SS II cannot possibly - 50 0 RESULTS AND DISCUSSION - - ' *0 ’ 50 100 reaction time. - be approximated as a single pseudo first order process. Rather , it appears to consist of two distinguishable phases; a rapid phase of inde terminate kinetic order for about 40 minutes a.t 120 *C , and a subsequent slower phase , conforming with first order kinetics. In Table 1 all the kinetic data are summarized. Syringyl type model compounds react faster than guaiacyl types in both soda and kraft treatments. For comparison , the ratio of rate constants was calculated. In soda treatment , SG I /GG I for k 1 = 2.7 and SG II/GG II for k was 1.7. In kraft treatment , SG I /GG I for k * = 1.8 2.8 , for k 2 = 1.6 2.3 ; SS I/GG I for k'= 4.4 6.3 , for k 2 =4.2 5.0; SG II /GG II for k * = 1.7 1.8 , for k 2 = 1.1 1.3 ; SS II /GG II for k 1 = 1.7 2.9 , for k 2 = l .8 2.0. - - - Fig.2. Reactions of GG I , SG I and SS I on - treatment with kraft liquor at 120 *C. - - - - - - - - - - - - - ) - - - - REFERENCES ergus , B.J .and Goring ,A , I.: Pulp Paoer Mag. Can. 19 , T315 320 ( 1969 ) 2. Procter , A.R • • Yean , W.Q . and Goring ,A.I.: Pulp Paper Mag. Can. 17 T445 453 ( 1967) 1. - . • •• reaction time - - - - Fig.3. Reactions of GG II , SG II and SS II on treatment with soda liquor at 120 C. # Table 1 . Temp. C - - 110 120 130 140 Soda 110 120 130 Kraft. k 1 k* 166 - GG I k 1 - xlO .min - Observed pseudo first order rate constants SG I k2 k1 k' 4.0 0.5 10.6 4.5 56.4 2.8 7.4 23.6 3.1 7.8 8.1 20.6 i 6.8 7.U 14.5 33.2 17.5 44 ,6 105 . GG II k2 k' k2 9.0 22.5 * 41.7 - - SS I " k2 2.6 6.7 17.4 13.1 37.9 102 0.5 0.7 1.4 . k1 - k 4.3 11.3 30.1 0.3 0.5 1.5 i - SG II SS II 2 k1 k1 2.0 4.7 1 0 . 1 0 1.8 1.3 2.9 2.4 2.5 6.6 4.4 11.4 3.2 5.6 11.1 6.7 refers to comsumptior cf rtarting material refers to formation GT guajacol or 4- methvlsyringol 7.3 121 activity ft r oxidative delignifi a * ion nt | birch Asplund pulp. THE EFFECT OF COBALT COMPLEXES ON OXYGEN ALKALI DELIGNIFICATION OF ASPLUND PULP - SADATOSHI MEGURO , KOKKI SAKAI and HIROYUKI IMAMURA - 4 KYUSHU UNIVERSITY 46 08 , 6 10 1 , HAKOZAKI , HIGASHI KU , FUKUOKA 812 , - - JAPAN . - ^ ABSTRACT Factors affecting the catalytic activity of - - cobalt complexes for ar oxygen alkali oxidat ion of guaiacol and oxidative delignification of white birch Asplund pulp were investigated , The cobalt complex which had a formal potential in an amphoteric region from approximately -0.3 to -* 0.3 V vs. the stand rd electrode had an ability - to catalyze the guaiacol oxidation , If the cobalt complex could form a romplex with the substrate , it could catalyze the guaiacol oxidation even when it did not have a formal ^ - - The concentration of guaiacol was 40 mmol / 1 . ^ Oxygen partial pressure was maintained at Mi during oxidation. The concentration of unreacted guaiacol was determined by GLC as reported previously( 2). Electrochemistry ; Cyclic vol tamrnograms of cobalt complexes were determined with a New Cyclic potential in that region , Only the cobalt complex with both higher catalytic activit y for the guaiacol oxidation and higher stability increases the delignification rate significantl . y - EXPERIMENTAL Cobalt comple ; Eight cobalt comple: es shewn ir: Table 1 were used. The concentration of cobal complex was 1.5 mmol /1. Pulping studies; White birch ( B* > tula Plat it phyll a var.japoni ca ) Asplund pulp (kappa no. 140) was cooked with 20% NaHCO , based on Asplunc pulp as NaOH , at 130 C for 2 hours at a liquor to pulp ratio 50 to 1 in a 4- liter stainlesssteel ro ary autoclave. Oxygen wa: introdu - e t <4 1.0 MPa at room temperature. Guaiacol oxidation ; Guaiacol was treated in 100 mmol /1 NaHCO solution with oxygen at 50 C for 3 hours using a 100 ml stainless steel autoclave. - Voltammetric Analyzer VAM 10 ( YANAGIMOTO MFC C LTD. ). A three electrode system was used , - consisting of a glassy carbon working electr . - - ^ INTRODUCTION Various investigation have been made to develo p the most suitable catalysts for oxygen alkali - delignification using some cobalt comple xes. The addition of a small amount of Co salen - to a single -stage oxygen pulping of white birch Asplund pulp caused a significant increase in the delign ifi cation rate as compared with the control( l ). The factors affecting catalytic activity of Co salen were investigated under guaiacol oxidation. The coordination of guaiacolate anion with Co salen - - - was necessary for the catalytic oxidation of guaiacol( 2). The stability of cobalt complexes was correlated closely with their ability to catalyze an oxidative delignification(3). Landucc 1( 4 ) demonstrated that the catalytic behavior of metals in phenoxy radical format ion from lignin model phenol and in catalysis oxidative de 1 ignification correlated of with the respective electrochemical behavi or of the metals as determined by cyclic voltammetry. In the present work , the electrochemical behavior of cobalt complexes and their ability to form a complex with the substrate were investigated and correlated to their catalytic ^ ode , a platinum wire counter electrode and a silver silver chloride standard electrode. Visible absorption spectra ; Visible absorption spectra of cobalt complexes in a 100 mmol/1 NaHCO solution were determined with a spectro photometer. Visible absorption spectrum of the mixture was measured in a glass cell fitted with plug immediately after guaiacol was added to the NoHCO.j soluton containing a cobalt complex tindei nitrogen bubbling. Stability measurement ; The NaHCO solution - KEYWORD: Oxygen alkali pulping , Asplund pulp , Cobalt complexes , Catalytic activity Phenol oxidation. - ^ - ^ ^ containing the cobalt complex was heated at 100 C for 30 min. and filtered by membrane filter ( 0.1 m ) after cooling. The concentration of ^ soluble cobalt in the filtrate was determined by photometric method using nitoroso R salt. The stability of the cobalt was expressed by the ratio of soluble cobalt in filtrate to added cobalt. RESULT AND DISCUSSION The cyclic voltamrnograms of cobalt complexes were determined in 100 mmol / 1 NaHCO solution. By the addition of Co salen , Co acacen and Co salpr , which had a formal potential in a narrow - - ^ - amphoteric region , the guaiacol oxidation was accelerated significantly as shown in Table t . On the other hand , Co acac , Co GL and Co EDTE did - not have it - - that region , and their effects on the guaiacol oxidation were small. Therefore , it in 167 Table 1 Facto rs affect ing the cataly tic activi ty of cobalt comple xes for guaiac ol oxidat ion in a 100 mmol / 1 NaHCO soluti ^ Comple xes•1 Electrochemical • behavior 2 Co-salen Co acacen Co-salpr CO-TEA CO EDTE Co-acac Co GL Co EDTA Complex formation with guaiacol•3 yes yes yes no no no no no - - - - with both higher catalytic . on activity for guaiacol oxidati 0 n and higher stability in alkali Catalytic - solution increased the de 1 ignification rate significant activity(%)•4 yes - ly under the applied condition 69.7 28.6 29.6 37.3 yes no yes yes no no no . Of the cobalt complexes investigated , Co salen was the most effective and decreased - 1.2 the kappa no. about 100 points as compared with control. 8.9 From these results , the 2.8 potential catalytic activity of 36.5 cobalt complex for oxidative •1 Ligand: salen ; bis-(salicylidene)-ethylenediamine , acacen ; bis - (acetylacetonato) ethylenediamine , salpr; bis (3 salicy - - - - aminopropyl) amine , delignification of Asplund pulp could be postulated reasonably by checking the electrochemical - 1 idene TEA ; triethanolamine , EDTE ; ethylenediamine tetraethanol , acac ; acetylacetone , GL ; gluconate , EDTA ; ethylenediaminetetraacetic acid. •2 "yes*' shows that the cobalt complex has a formal potential in a region from approximately 40.3 to 0.3 V , as determined by CV. # 3 "yes" shows that the cobalt complex has an ability to form a complex with guaiacol. •4 Differential percentage of residual guaiaco l between non additive and additive oxidation. - behavior as determined by CV , the ability to complex with substrate as determined by - visible absorption spectra and the stability as determined by concentration of soluble cobalt - seemed that all cobalt complexes which had a formal potential in an amphoteric region approximated by 0.3 V vs. the standard electrode exhibited some catalytic activity for the guaiacol oxidation ,in a similar manner as metals investigated by Landucci( 4). But CO TEA and - - Co EDTE catalyzed the guaiacol oxidation effecti vely without having a formal potential in an amphoteric region. This result showed that the potential catalytic activity of cobalt complexes on the guaiacol oxidation could not be postula ted only from their electrochemical behavior as determined by cyclic voltammetry ( CV ). Co-salen , Co acacen , Co TEA and Co EDTE formed a complex with guaiaco REFERENCE ( 1 ) Meguro S.; Sakai ,K.: Mokuza i Gakka ishi , US2, 668 ( 1980). ( 2) Meguro S.; Sakai , KImamura ,H.:ibid. 30.1011 ( 1980) (3) Meguro S. ; Imamura ,H.: ibid , in press. (4) Landucci ,L.L :Tapvi , 6 ,7l ( 1979). £ . . . . . i i r:\ l as their - - - screening potential catalysts for phenol oxidation , the ability to form a complex with substrate must be one of the most important factors besides the electro chemical behavior. In order to catalyze the oxidative de .ignlfication of white birch Asplund pulp , the stability of the cobalt complex becomes another Important factor. s shown in hig.l , only the cobalt complex - - . 168 100 C for 30 min.. - visible absorption spectra changed significantly by addition of guaiacol.lt seemed that Co TEA and Co EDTE were activated by forming a complex with substrate , similar to Co salen in our previous WOTK( 2) Accordingly , when . in filtrate after heating at - Co salen cf a c 0) H T3 c ao O c 4 - Co EDTE t’ eCT CO CO ao 50 a CO T3 £Co-salpr( G- ) 50 Co TEA CO T3 N C >> O .H u (0 H - 0 - ° V <6 • >» ( °* ioo - Co GL acac . - .Co 0 CM O S§ - Co EDTA / 50 100 Stability of cobalt complexes (%) . FiR 1 Factors affecting the catalytic activity of cobalt complexes for oxygen alkali pulping of white birch Asplund pulp. - i ORGANIC AC 10 PULPING OF WOOD. OVERVIEW Of APPL7 CATIOhS stage , energy requirements for ethanol recovery and the need for total byproduct utilisation ma PART I. - AN limit further development (1 4). Less attention has been paid to the use of RAYMOND A. YOUNG . JAMES L. DAVIS , EVA BARBARA WIESMANN AND KENNETH W. BAIERL - DEPARTMENT OF FORESTRY UNIVERSITY OF WISCONSIN MADISON , WISCONSIN USA 53706 organic acids as pulping agents. BIODYNE CHEMICALS , INC. 2121 HARRISON STREET NEENAH , WISCONSIN USA 54956 ABSTRACT The use of organic acids in pulping is briefly reviewed. Laboratory scale cooking of aspen and spruce chips demonstrated that good delignifica tion can be achieved with aqueous acetic acid (50 95%) at 175 220°C for 30 60 minutes, The stronger reaction conditions are necessary for softwoods. Acetic acid can be recovered :rom waste liquors by liquid liquid extraction th ethyl acetate. A revolutionary new pulping process based on ethyl acetate/acetic acid/.;ater is also described. Chemical recovery costs are greatly reduced because a two phase liquid 1iquid system results after proper adjurtment of the solvent ratios. - - - - - - - INTRODUCTION There are a variety of serious problems asso ciated with conventional pulping processes , such as kraft and sulfite. The predominant kraft process is malodorous , energy intensive , gives low pulp yields and requires very high capital - expenditures. The latter requirement will limit future investment in kraft pulping. Conventional acid sulfite pulping is plagued by pollution problems. To circumvent these diffic ulties , organic acid pulping of wood has been investi gated as an alternative method. - Alternate Pulping Systems During the past 20 years , a variety of non conventional solvent pulping methods have been explored. Solvents such as glycols , amines , - - promise as a pulping agent. ACETIC ACID PULPING It has been known for a long time that acetic acid acts as a solvent for lignin , However, there are few published investigations on the us of acetic acid for pulp production. In 1944, Wiltshire (6 ) boiled wood chips in glacial aceti acid at atmospheric pressure and was able , by th addition of a small amount of sulfuric acid , to produce satisfactory pulp. Herdle et a 1 . (7) also conducted pulping experiments using strong acid catalysts in acetic acid media , Their wor . focused on the production of d .ssolving pulp for conversion to cellulose acetate, but some of their results have a wider significance. DeEaas and Lang (8) were able to eliminate the need for a strong acid catalyst by increasing the temperature at which the pulping was carried out. They obtained pulps with good strength properties from hardwood and softwood chips by using a solution of 85 96 % acetic acid at a temperature in the range 150 205°C for 2 5 hours. They asserted that water content in excess of 15% (of the cooking liquor) reduced the pulp yield as a result of polysaccharide hydrolysis, slowed the delignification process , and caused precipitation of the lignin. Recent work in our laboratory has convincingly demonstrated that a pulp with a satisfactory Kappa number (10 40 ) may be obtained with an excellent yield (50 60% ) by cooking chips in a liquor composed entirely of acetic acid and water at a liquor to wood ratio of 4:1 to 8: 1. The maximum degree of delignification at the lowest reaction temperature was observed for aspen when the cooking liquor contained 75% acetic acid by volume. An increase in the acetic acid concen tration from 75 % to R 7.5 by volume improved the * selectivity of the process for lignin dissolution (Figure 1) and increased the pulp yield for a ( fixed Kappa number. However , the de 1 IGNIFICATION rate was lower in the 87.5% solution , and it was - - - ketones, dimethylsulfoxide , dioxane, phenol, nitric acid , and aliphatic alcohols , have been evaluated as pulping media. Poor pulp quality , chemical losses and recovery , and environmental problems have plagued the furthe r development of most of these processes. Aqueous ethanol pulping has been recently pro moted for delignification of hardwoods. However , catalysts such as mineral acids, Lewis acids or magnesium chloride , are necessary to pulp soft woods. Pulp strength is generally comparable to sulfite pulps. Although the aqueous ethanol organosolv process has reached the pilot plant - - Buchholtz and Jordan (5) described a pulping process in which hardwood or softwood chips were boiled in an RO 1 formic acid solution containing a catalyst (not identified ). Hardwood chips were reportedly pulped to a Kappa number of 60 65 (i.e• r lignin content of 9 10 % ) in 45 minutes with a yield of 59 %. However , acetic acid shows much greater - - - - - necessary to increase the reaction temperature or to extend the reaction time in order to obtain 169 < the desired Kappa number. For every reaction temperature and liquor composition , there existed an optimum cooking time , at which delignification reached a maximum value. Cooking beyond that point led to further lignin condensation and an increase in the pulp Kappa number (9). The acti vation energy for delignification of aspen in 50 87.5% acetic acid ranged from 38 to 46 kcal/ mole. The importance of washing the cooked chips with solutions that are good lignin solvents was demonstrated for the small batch cooks. Washing with fresh cooking liquor and acetone proved to be very effective for removing the lignin frag ments created during the cooking step. Aqueous acetic acid pulping of softwoods proved characteristically more difficult. Stronger conditions were necessary to obtain spruce pulps with lignin contents comparable to aspen pulps. For example, to obtain a Kappa number in the range of 20 40, the acetic acid concentration must be 75 87% by volume, the temperature 185 215°C , with a total cooking time of 1 2 hours. The effect of reaction time and temperature on delignification of spruce is shown in Figure 2. Satisfactory strength properties were obtained for both aspen and spruce pulps at optimum cooking conditions. The highest strength prop erties and yields and the lowest lignin contents were obtained with the cooking conditions shown in Table 1. - for recovery of acetic acid by liquid liquid extraction. A computer model of acetic acid pulping and recovery based on ASPEN software (PDP 1134 Computer ) is under development in the Department of Forestry. - - - - - - - - Acetic Acid Concentration Species Aspen Spruce Overview of Acetic Acid Pulping Satisfactory pulps can be produced with aqueous acetic acid cooking liquor , From a recovery standpoint , it would be desirable to have a low concentration of acetic acid in the fresh liquor , However , a high concentration of acetic acid (> 75%) must be maintained in the liquor to retain the desired pulp properties and cooking conditions, As the water content of the cooking liquor is increased , the delignification selectivity is decreased and pulp strength prop - erties suffer due to increased hydrolysis of polysaccharide components. A high concentration of acetic acid is neces sary in the pulping liquor because the acetic acid is thought to perform two roles, It is a source of the hydronium ions for acceleration of the acid hydrolysis of lignin and a solvent for the lignin fragments produced by the hydrolysis reaction. Only a small amount of water is neces sary for dissociation of the acetic acid , What is needed , then , is a substitute solvent for water that is also miscible with both acetic acid and water. - - Maximum Temperature 185°C 2 20°C 87% 87% - - Time Liquor to VJood Ratio Kappa Number 60 min. 4/1 10 45 min. 8/ 1 16 Pu’o Yield 55 46 Table 1. Optimum Acetic Acid Cooking Conditions • Acetic Acid Recovery An important consideration with any pulping process is chemical recovery , both for economic and environmental reasons. There are a number of possible alternatives for recovery of acetic acid from waste streams. The most viable and p. oven method is liquid liquid extrac tion. A variety of solvents are available for organic icid extraction including 2 butanone , trioctyl phosphine and several amines ( 4 ). Ethyl acetate is also effective for liquid liquid extraction jf acetic acid from aqueous solutions and has a low cost. This ester has a high distribution coefficient (D * 1.11) indicating that it will a r l.i ip acetic acid with ease , requiri ng only smal 1 volumes Since ethyl acetate could also be produced at the mill site from acetic acid and ethane 1, this ester is the solvent of choice - - - . 170 - AN ETHYL ACETATE/ACETIC ACID/WATER PULPING SYSTEM It is proposed that ethyl acetate serve as the substitute solvent for water in acetic acid pulping to give a new solvent based pulping process comprised of ethyl acetate , acetic acid and water (acetate pulping). The positive impl cations of the addition of ethyl acetate to the pulping medium are profound and include: 1. A reduction in the amount of water required in the system. 2. Reduced cooking time. 3. Lower pulping temperatures for given cooking pressures. 4. Higher strength pulps. 5. Higher yields. 6. Enhanced solubility of lignin in the pulping solvent. 7. Simplified recovery of organic chemicals. - 1 00 90 80 - 70 . i e O -E 60 Z o a CL o 50 - - 3 40 - * •r 30 - i •* : * 20 - .. ; t* 10 . •: * • * 0 T 0 50% HAc Figure 1. Effect of I 2 4 + Reaction Time ( hrs ) o 75% HAc 6 87.5% HAc etic acid concentration and cooking time on deiignification of aspen chips. 130 120 110 100 90 t> E 3 80 - 70 Z o a a o * 60 50 - 40 - 30 - \ A A 20 10 - 0 2 0 D figure 2. 1 60 C - 4 4 Reaction Time ( hrs ) O 170 C 185 C 6 8 A 220 C Effect of temperature and cooking time on delignification of spruce chips. 171 Ethyl acetate is entirely miscible with acetic acid and water , however , by proper adjustment of the solvent ratios , a two phase system results ; an organic phase composed of ethyl acetate and acetic acid , and an aqueous phase. This facile separation (decantation) drastically reduces energy requirements for chemical recovery. Sugars are obtained from the aqueous phase for fermentation and a pristine lignin can be easily precipitated from the organic phase, The lignin properties are characteristic of other organosolv lignins which are uncondensed and contain no sulfur. Thus, possible byproduct utilization of lignin is a distinct possibility. Another less obvious benefit of acetate pulping is that much less acetic acid is neces sary in the pulping liquor. Since ethyl acetate has good lignin solvent properties, it can be substituted for acetic acid as well as water. This is demonstrated in the preliminary results shown in Table 2. As low as 26 % acetic acid , with ethyl acetate and water , gives a good yield and a very low lignin content, Further reduc tions are probably possible. The recovery schemes would be greatly simplified at lower acetic acid concentrations. 5. - BUCHHOLTZ , M. and R. JORDAN. 1983. Formic Acid Wood Pulping Could Yield Valuable Chemical Products. Pulp & Paper 57(9), 102 104. WILTSHIRE , W. A. 1944. Acetic Acid Digestion of Wood. Proc. Tech. Sect. Paper Makers' Assoc , of Great Brit. & Ireland. 24 , 347 353. HERDLE, L., L. PANCOAST and R. MacCLAREN. 1964. Acetylation Celluloses from Pulping of Wood with Acetic Acid. Tappi 47(10), - 6. - 7. - 8. - 9. 617 620. DeHAAS , G. and C. LANG. 1971. Non Catalytic Process for the Production of Cellulose from Lignocellulosic Materials Using Acetic Acid. U.S. Patent 3 ,553 ,076. YOUNG , R. A. , J . L. DAVIS and E. B. WIESMANN. 1985. Organic Acid Pulping of Wood. Part II. Acetic Acid Pulping of Aspen , - - Holzforschung , accepted. - Ethyl Acetic acid , % acetate , % Yield , % 50% 75% 55% 33% 52 % 48% 33% 49 % 26% Table 2. Kappa No. 30 - 10 ; - 8 48% 11 Acetic Acid and Ethyl Acetate Pulping of Aspen - ^ 1 165 170 C , 3 hours total cooking ° remainder of liquor is water. time , f* c L REFEPJNCES i. DIEBOLD , V. B. , W. F. COWAN and J. K. WALSH, Solvent Pulping Process, U.S. Patent 4 , 100 ,016 , July 11, 1978. 2 PASZNER , L. and P. C. CHANG. 1981. Organo solv Delignification and Saccharification Process for Lignocellulosic Plant Materials. Canadian Patent 1 , 100 , 266. 3. SARKANEN , K. V. 1980. Acid Catalyzed Delignification of Lignocellulosics in Organic Solvents. In: Progress in Biomass Conversion , Vol. 2 , K. V. Sarkanen and D. A. Tillman , ed. Academic Press , N.Y. , p. 128 144. 4 . YOUNG , R. A. and S. ACHMADX. 1983. Effi cient Utilization of Woody Biomass: A Cellulose Particleboa rd Synfuels Model. In: Biomass Utilization. W. A. Cote , ed., Plenum Press , N.Y., p. * 585 610. . - - - - - - 172 - ms 'c 9* \ \ c < progressive cell wall delignification . Deara at ^ on by brown r o t fungi caused an enhancement i f concentric layers within the Sp of softwood fibres during t a r 1 / STUDIES Oh liOOD FIBRE STRUCTURE USING BIOLOGICAL DECAY ORGANISMS stages before lignin skeletons were produced . Fu the ^ evidence for non - homogeneity was suggested by the f r . GEOFFREY DAN IE AND THOMAS NILSSON SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES concentric localization of soft r o t c a v i • I P . within | Sp of wood fibres and by the enzymic diffusion from b DEPARTMENT OF FOREST PRODUCTS , SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES , BOX 7008 , S 750 07 UPPSALA , SWEDEN hyphae produced by white rot fungi during p e n e t r a t i o n - wood fibre walls . The results which give strong evidence to support non - homogeneous and concentric distribution o * Sp fibr wall components will be discussed i n relation to curr ABSTRACT ideas on fibre structure and component Despite considerable research involving the use of decay organisms both physical and a wide range of chemical techniques , . ^ degradation by the distribution of the major cellular components ( lignin , cellulose , hemicelluloses ) within the Sp cell wall of wood fibres remains a controversia issue . Apart from examples which show distinct polylaminate walls , the Sp layer cf wood fibres i s generally considered t o be a rather homo i - geneous entity which i s composed ultrastructurally of an array of lamellae . Reports are available however , particularly i n the older literature which refer to the « occurrence of concentric layers within the Sp of fibres which may represent variations i n structure and / or component distribution . However , since the majority of these observations were made on samples after the applica tion of various swelling agents , the authenticity of the layers has not been f u l l y accepted . To add further suspi - cion the apparent difficulties i n demonstrating such layers i using UV or electron microscopy , particularly i n softwoods has lead to further sceptism . In the present study , biological decay organisms have been used as " tools " to select and partially degrade the Sp wall layer of fibres in order to obtain further « evidence for the distribution of the major cellular components . The study involved a correlated light and electron microscopic investigation of fibre walls at various stages of decay caused by a range of fungal ( white , brown and soft r o t species ) and to a lesser extent bacteri al and actinomycete types . For a comparison , both deligni - fied ( acid chlorite ) , hydrofluoric acid treated and chemically pulped ( sulfate, sulfite ) fibres were compared with the decay patterns produced i n fibre cell walls by the microorganisms - * . The characteristic , preferential and mild manner of the decay process by the white rot fungus Schizophyllum commune gave strong evidence for a concentric and non - . homogeneous distribution of Sp wood components Decay by S • commune caused the development of pronounced concen - t r i c " slits " within the Sp layer of fibres the location of which showed a close similarity to previously reported concentric layers , as well as indicating the existence of ' weak regions " . A similar form of Sp delamination was recognised i n chemically pulped , delignified and acid treated fibres . Sp delamination was also recognised but less frequently with cellulase - less Phlebia mutants during * 17 I f r u p t u r e o f t h e 6“ a r y l e t h e r b o n d s the SET and is the slow step in deligmfication, uent types t i t s b u s t adduct mechanisms predict tha on the aromatic fragments could have large ef fects on degradation rates, Phenolate ions, as produced in the adduct mechanism , are electron fragment * . - TRANSFER REACTIONS IN PULPING SYSTEMS •LECTRON - - R. D I M M E L A N D L O I S F. P E R R Y )O N A L D rich species and thus are stabilized by electron Phenolate w i t h d r a w i n g r i n g 9 u b s t i t u e n t s (8 ) . INSTITUTE OF PAPER CHEMISTRY IPP ETON , WISCONSIN "H E 4 - r a d i c a l s (S E T m e c h a n i s m ) a r e e l e c t r o n p o o r y eler tron species and aie therefore stabilized b - 4 - r e l e a s i n g r i n g s u b s t i t u e n t s ( 8 ). t s T "’ A C T containing a phenolic Lignin model compounds rings R had a large effect on fragmentation reac - : t o n s o f t h e m o d e l s u n d e r "s o d a ” c o n d i t i o n s b u t I O e f f e c t u n d e r "s o d a / A Q" o r "k r a f t " c o n d i t i o n s . Substituent changes on jndei ring A had large effects ' relationships indicate that the slow step in the nechantsm for model fragmentation under soda - cleavage of the 0 aryl ether bond a n d u n d e r 9o d a / A Q a n d k r a f t c o n d i t i o n s i s conditions is De 1 ignification, Mechanisms , Lignin Models, Fragmentation, Synthesis This The reactions outlined in QM AHQ Q M' AHQ studies of lignin QMs in organic - lignin QM to give step, the adduct - - A key difference between the pure ionic and SFT mechanisms of delignification is that the produces only phenolate wbile the latter gives v QM’ 9 QM ’ “ QM AHQ (a ) AHQ ( b) — 4 (c ) QM * QM * ArO A r * 0* (d ) QM 1 ArO A r "0• (e) fl - * that quinoneraethide , i .e. , E q. Many SET react ions are characterized by SET steps between species a s p a i t o f a c h a i n m e c h a n i s m ( 1 0 1 2 ); t h e r e f o r e , - t h e e q u i l i b r i u m i n d i c a t e d b y E q . (c ) s h o u l d occur and should be shifted in the direction of the more stable species . Depending on the sta - b i l i t i e s o f A r 'O * a n d A r "0 « , f i a g r a e n t a t i o n s t e p s ( d ) a n d (e) w o u l d b e e x p e c t e d t o p r o c e e d a t d i f - p u l p i n g s y s t e m s ( 7 ), MECHANISM DIFFERENTIATION former QM ( b ) p r e f e r r e d t o E q . ( a ). l a t e i o n s ( 3 6). T h i s c h e m i s t r y i s a n a l o g o u s t o aorao o f the ionic m e c h a n i s m s proposed for s o d a and kraft - q u i n o n r a e t h i d e s (Q M reactions with a n " a d d u c t "; i n a s u b s e q u e n t fragments to AQ and two phono — T - s o l v e n t s ( 2 ). I n c o n t r a s t t o t h i s "r a d i c a l " v i e w o f A H Q induced delignification chemistry , Scheme It o f f e r s a g e n e r a l l y m o r e a c c e p t e d " i o n i c" m e c h a ~ n i a m. H e r e A H Q 2 a d d s t o t h e a c a r b o n o f a ~2 and QM') were gen 2 could react with orated simultaneously , AHQ e i t h e r o n e. I f o n e o f t h e q u i n o n e m e t h i d e s ( i .e • » Q M ') f o r m s a m o r e s t a b l e r a d i c a l a n i o n , y o u 2 would expect AHQ " to preferent ia l ly undergo SET If two Scheme l have been ^ d i f f e r e n t s u b s t i t u e n t s: contain - verified by room temperature electrochemical between reactive Consider , for example, the following SET reactions which might exist during the competitive reactions of in situ generated QM l i g n i n b o n d r u p t u r e s ( a n d t h u s d e l i g n i f l c a t i o n ), interaction i n t e r m e d i a t e s o c c u r s. S i n g l e e l e c t r o n t r a n s f e r (S E T) r e a c t i o n s o f f e r a w a y t o r e m o v e l i g n i n f r o m w o o d ( I ). l i g n i n q u i n o n e r a e t h i d e (Q M ) s p e c i e s c a n l e a d t o the is possible if certain steps is are reversible and t NTRODUCTION Scheme I presents a mechanism by which SET reac t i o n s f r o m a n h y d r o q u l n o n e ( A H Q) s p e c i e s t o ^ - vide information about the mechanism of the QMs which q u i n o n e m e t h i.d e f o r m a t i o n . < EYWORDS ; they are located , aromatic ring substituents may o r m a y n o t i n f l u e n c e t h e r a t e s o f Q M g e n e r a t i o n. Substituent effects may, however , still pro s l o w s t e p. - These substituent reactivity a In fact , quinoneraethide generation is n i s m s. p r o b a b l y t h e s l o w s t e p (9). D e p e n d i n g o n w h e r e fragmentation step, even if QM generation s o d a /A Q a n d k r a t c o n d i t i o n s f o r m o d e l l e g r a d a t i o n s. 4 - A ind B, have been synthesized and degraded under Substituent changes on i variety of conditions, ring - multistep reactions, of which the fragmentation s t e p s roav not b e t h e s l o w s t e p s in t h e raecha - • A ” r i n g , a-O H , a n d 0 a r y l (r i n g "B ") e t h e r , rfith d i f f e r e n t s u b s t i t u e n t s l o c a t e d o n De l i gn i f i cat ion of wood and simple fragmen tation of lignin model compounds are, however , ion fragments, some phenolate radical f e r e n t r a t e s. In a competitive degradation of two models reacting via SET mechanisms the product distri but ion should reflect either the stabilities of -^ the QM tadical ions oi the stabilities of the . extractives that are toxic to other microorganisms 3 There i s no need for cloning " ligmnase " genes into . these bacteria s i n c e they already possess lignolytic WOOD - DEGRADING BACTERIA - NEW MICfff 3 ES FOR BIOCONVERSION OF LIGNOCELLULOSE THOMAS NILSSON AND GEOFFREY DANIEL SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES . . A presumably more rapid invasion of the substrate compared with fungi . The view that myceliated organisms , activity 4 fungi and actinomycetes have a better capacity for inva - DEPARTMENT OF FOREST PRODUCTS , SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES , BOX 7008 , S - 750 07 UPPSALA , SWEDEN sion seems to a large extent be a misconception 5 . . A quicker and larger build up of biomass compared with . fungi 6 . Nitrogen fixation has been found to occur i n substrate: which are being attacked by wood - degrading bacteria . Thus ABSTRACT there appears to be a possibility of combining nitrogen Recent studies have clearly demonstrated that bacteria are able to degrade wood . Results from earlier studies fixation with bioconversion of 1 ignocellulosic materials . indicated that lignin protected wood from being degraded by cellulolytic bacteria . This led to the erroneous assumption that bacteria are unable to degrade wood . Wood - degrading bacteria seem to constitute a very specialised group that are adapted to lignified substrates . These bacteria have recently received considerable atten t i o n within tv,e field of wood preservation . This interest has been evoked by the discovery that they may cause . significant degradation of preservative treated timber Their wood - degrading activity indicate that they , in analogy with white r o t fungi , nay have a potential for bioconversion of 1 ignocellulosic materials . Wood - degrading bacteria attack 1 ignocellulose fibres basically i n two diffrent ways . The f i r s t type i s a form of erosion starting from the cell lumen ( erosion bacteria ) and the second i s characterised by penetration of the bacteria into the fibre wall where subsequent degradation occurs ( cavitation bacteria , tunnelling bacteria ) . The different forms and patterns of attack on wood substrates indicate that a rather large number of different species exist . However , only one wood - degrading bacterium seems so far to have been isolated into pure culture . The information on wood - degrading bacteria i s s t i l l rather limited . Only a few types of attack have been . All bacteria attack the carbo - described i n any detail hydrate fraction i n wood and we have observed morphologi - cal evidence for lignin degradation . Experiments with wood containing 14 C labelled lignin , 13C - NMR studies , and - Klason lignin analyses have shown that tunnelling bacteria cause a substantial degradation of the lignin i n wood . There appears t o be a number of advantages i n using wood - degrading bacteria for the bioconversion of 1 igno cel lulose: - 1 . No preconditioning of the substrate is required. This i s i n contrast to ordinary cellulolytic bacteria . High lignin levels do not prevent degradation by wood - degrading . bacteria Substantial attack has been observed i n ligno cellulosic materials with lignin levels well above 30 percent ? . . Tunnelling bacteria have a remarkable a b i l i t y to degrade durable timbers . This seems t o indicate that they may be employed for bioconversion of substrates which contain 175 - fr a g r o e n t s . t f r u p t u r e o f t h e 0 a r y l e t h e r b o n d s T and i s t h e s l o w s t i* p i n d e l i g n i f i c a t i o n , t h e S E adduct mechanisms predict that substituent types on the aiomatlc fragments could have laige ef - ELECTRON TRANSFER REACTIONS IN PULPING SYSTEMS Fhenolate THE INSTITUTE OF PAPER CHEMISTRY A PD ~E T O N , W I S C O N S I N - - r a d i c a l s ( S E T m e c h a n i s m) a r e e l e c t r o n p 0 0 r ectron species and are therefore stabilized by el r e l e a s i n g r i n g s u b s t i t u e n t s (8 ). D e l 1 g n 1 f 1c a t 1o n o f w o o d and s i m p l e f r a g m e n t - - ABSTPACT containing a phenolic Lignin model compounds - - MA " r i n g , a O H , a n d 0 a r y l (r i n g "B ") e t h e r , with different substituents located on rings A - Substituent changes on ring A had large effects -low the I 9 step in the p r o b a b l y t h e 9 l o w s t e p (9). - This is QM AHQ Q M' AHQ - l i g n i n q u i n o n e m c t h 1 d e (Q M ) s p e c i e s c a n l e a d t o l i g n i n b o n d r u p t u r e s (a n d t h u s d e 1 1 g n 1 f 1 c a t 1 o n ). Scheme I have been verified by room temperature electrochemical s t u d i e s o f l i g n i n Q M s i n o r g a n i c s o l v e n t s ( 2 ). * lignin QM to give step, the adduct a n "a d d u c t " ; - in - analogous to l a t e 1 0 n s (3 6). T h i s c h e m i s t r y i s some of the ionic mechanisms proposed for soda a n d k r a f t p u l p i n g s y s t e m s ( 7 ). MECHANISM DIFFERENTIATION SET mechanisms of delignif ication produces only phenolate wbile the latter gives some ton is ionic and that the fragment s, phenolate radical ~2 “ QM AHQ (a ) v Q M' AHQ (b) ~2 ^ (c) QM* QM 1 QM QM * ArO Ar *0 QM * ArO A r "0• - (d ) (e ) - I f t w o q u i n o n r a e t h i d e s (Q M a n d Q M * ) w e r e g e n 2 could react with erated simultaneously , AHQ I f o n e o f t h e q u 1 n o n e m e t h 1 d e s ( i .e., e i t h e r o n e. Q M ') f o r m s a m o r e s t a b l e r a d i c a l a n i o n , y o u 2 would expect AHQ " to preferentially undergo SET r e a c t i o n s w i t h t h a t q u i n o n e m e t h i d e , 1.e. , E q . - ( b ) p r e f e n e d t o E q . ( a ). fragments to AQ and two pheno A key difference between the pure reactive - of AHQ a subsequent - between steps d i f f e r e n t s u b s t i t u e n t s: contain QM i n d u c e d d e 1 1 g n 1 f 1c a t 1 o n c h e m i s t r y , S c h e m e ll o f f e r s a g e n e r a l l y m o r e a c c e p t e d "i o n i c" m e c h a 2 adds to the a carbon of a n 1 3 m. H e r e A H Q interaction certain ^ the 19 . QMs which Scheme I presents a mechanism by which SET reac t i o n s f r o m a n h y d r o q u 1 n o n e (A H Q) s p e c i e s t o possible if 19 are reversible and S i n g l e e l e c t r o n t r a n s f e r (S E T ) r e a c t i o n s o f f e r a w a y t o r e m o v e l i g n i n f r o m w o o d ( 1 ). view Depending on where vide information about the mechanism of the lNTRODUCTION I n c o n t r a s t t o t h i s "r a d i c a l " generation - 19 they are located , aromatic ring substituents may o r m a y n o t i n f l u e n c e t h e r a t e s o f Q M g e n e r a t i o n. Substituent effects may , however , still pro K E Y W O R D S: D e l i g n i f i c a t i o n , M e c h a n i s m s , L i g n i n Models, Fragmentation , Synthesis in the raecha Consider , for example , the following SET reactions which might exist during the competitive reactions of in situ generated - The reactions outlined in t intermediates occurs mechanism for model fragmentation under soda conditions is cleavage of the 0 aryl ether bond and under soda/A Q and kraft conditions q u i n o n e r a e t h i d e f o r m a t i o n. steps In fact , qu1 nonemeth 1 de s l o w s t e p. These subst 1 tuent react 1v 1ty relationships indicate that n 1 a m s. 9 low be the fragmentation step, even if QM generation s o d a/A Q and k r a t c o n d i t i o n s for model d e g r a d a t i o n s. tat ion of lignin model compounds are, how •ve1 , multistep reactions , of which the fragmentation s t e p s raav n o t and B, have been synthesized and degraded under a variety of conditions, Substituent changes on ring H had a large effect on fragmentation reac t i o n s o f t h e m o d e l s u n d e r "s o d a ” c o n d i t i o n s b u t n o e f f e c t u n d e r "s o d a / A Q" o r "k r a f t " c o n d i t i o n s . former ions , - D O N A L D R . D I M M E L A N D L O I S F. P E R R Y unde1 - a9 fects on degradation produced in the adduct mechanism , are electron rich species and thus are stabilized by electron Phenolate w i t h d r a w i n g r i n g s u b s t i t u e n t s (8). rates, i Many SET reactions are characterized by SET steps between species a s p a i t o f a c h a i n m e c h a n i s m ( 1 0 1 2 ); t h e r e f o r e , - the equilibrium indicated by Eq occut and should be shifted the more stable species . in . (c ) s h o u l d the direction of Depending on the sta - b i l i t i e s o f A r ' O * a n d A r "0 * , f r a g m e n t a t i o n s t e p s (d ) a n d (e ) w o u l d b e e x p e c t e d t o p r o c e e d a t d i f - f e r e n t r a t e s. In a competitive degradation of two models 1reacting via SET mechanisms the product d 1s t r but ion should reflect eithet the stabilities of the QM radical ions or the stabilities of the SCHEME T Delignification via AHQ - induced SET Reactions CH— O 4 r.H,o CH :0: * - : . AHO 2 O M- * = • . A H Q- CH CH CH CH "' + AHO -f AHO or 2 + or AQ AHO “ O: * : or • * SCHEME IT Delignification via AHQ Adduct Reactions CH 3 O CH ^ CHjO N \ CH 2- O '/ B \N A OCHj O AHQ 2 O- QM adduct 1 OCHj + B phenol fragments 178 resulting phenolate ion a n d r a d i c a l f r a g m e n t s. - Since QM AHQ adduct reactions are reversible reflect ( 1 3), s i m i l a r a r g u m e n t s a p p l y ; p r o d u c t d i s t r i b u from competitive reactions will tions either the stabilities of the adducts or the stabilities of the resulting phenolate This report covers the synthesis and reac ferent A and ring to detect is - goal ring B substituents Our provide information defining specific reaction mechanisms , especially with regard to QM a d d i t i v e r e a c t i o n s. - - 2 A E , 3 A , a n d 4A h a v e b e e n s y n t h e s i z e d a n d s u b . The slow step in the mechanism for model fragmentation undei soda conditions is the types of degradation reac of 0 aryl - - - cleavage of the 0 aryl ethei was taken as an indication - The slow step in the mechanism for model frag - - p h e n o l s 6 a n d 7 , v i n y l e t h e r s 8A D , a n d g u a i a c o l amounts, apparently of C tion and arises from a cleavage reac - a The degradations of the models were per f o r m e d i n t h e p r e s e n c e o f N a O H ( s o d a ), N a O H a n d - a n d N a O H , g l u c o s e a n d A Q (s o d a / A Q ). REFERENCES l. D I H M E L , D.R . ( 1 9 8 5 ). 2. D I M M E L , D. R . , P E R R Y , L.F. , P A L A S Z , P.D. , The fr ag efficiencies followed the order soda/ kiaft > glucose control > soda , regardless of the model type which was being degraded. . CM — CM ,— CM CM . JM CHOH 1 O B S T , J . R . , L A N D U C C l , L.L. , A N D S A N Y E R , N . T a p p i 6 2( 1 ): 5 5 ( 1 9 7 9 ). 4. L A N D U C C l , L.L . 5. G I E R E R , J. , L I N D E B E R G , 0. , A N D N O R E N , l . H o l z f o i s c h u n g 3 3: 2 1 3 ( 1 9 7 9 ). 6. A M l N O F F , H. , B R U N O W , G. , M I K S C H E , G.E. , A N D OCH , OH H CM a . OCH» 4 r , OCH . , , JR, R 4 R - R 5 • H 6 R CH1 7 R 8. M A R C H , J. A d v a n c e d O r g a n i c C h e m i s t r y , 3r d . n R A CH n C« C OCH , O CM f NO r OH - e d . , W i l e y 6 S o n s , N e w Y o r k , 1 9 8 5: 1 5 1 1 7 0 , 2 3 7 2 5 0. . H . , * CH O CM I OH G I E R E R , J. P a p e n P u u 6 1 : 4 4 1 (1 9 7 9). H o I z f o r s c h u n g 3 6: 4 3 ( 1 9 8 2). OH M CM 2 P R\ T a p p i 6 3( 8): 9 5 ( 1 9 8 0). 7. P O P P t U S , K. . £ W o o d C h e m T e c h n o 1 5: 1 5 3. R f6 1 , £ W o o d C h e n T e c h n o l 5: l A N D C H U M , H. L . ( 1 9 8 5). - AQ K - m a t i o n. N a S H (k r a f t ), N a O H a n d g l u c o s e ( g l u c o s e c o n t r o l ), mentation - under soda /AQ , soda /glucose and kraft conditions appears to be qu1nonemethide for very small in A. ring - mentation Other products observed included vinyl 9. T h e l a t t e r , o n l y p r e s e n t alkalinity - ether fragmentation and , consequently , delignifica bond ; the of the solution affects the extent of model frag m e n t a t i o n v s. v i n y l e t h e r b y p r o d u c t f o r m a t i o n . T h e q u a n t i t y o f p h e n o l s 5A E p r o d u c e d t 10 n . to defining the m e c h a n i s m s. - t ions informative slow steps in soda are very a n d s o d a /a d d i t i v e d e g r a d a t i o n s , b u t h a v e n o t y e t allowed distinction between SET and adduct Lignin model compounds of the type 1 A F , various I w i t h s i n g l e m o d e l s. with regard RESULTS jected to V a r 1 a t 1009 m r i n g A substituents had large effects on the degree CONCLUSIONS The results to date reactivity differences which will i b u t n o t t h e o t h e r c o n d i t i o n s. i .e. , 1 A a n d I D , i n d i l u t e s o l u t i o n s , s h o w e d n o major differences from degradation performed of lignin model compounds which have d 1 f , ring o f f r a g m e n t a t i o n , w i t h t h e f o l l o w i n g o r d e r: 4 > I A > 3. C o m p e t i t i v e d e g r a d a t i o n o f m o d e l p a i r s ion f r a g m e n t s. tions B s u b s t i t u e n t (R j) a f f e c t e d t h e fragmentation efficiencies under soda conditions The - ^ 9. M I K S C H E , G.E. ( 1 9 7 2 ). A c t a C h e m S c a n d 2 6: 4 1 3 7 . K O R N B L U M , N. ( 1 9 7 5) A n g e w C h e m I n t E d 1 4: 7 3 4 11 R U S S E L L , G. A. C h e m S t o s o w 2 6: 3 1 7 ( 1 9 8 2). 1 2. M A R C H , J. 10 . . , Advanced Organic Chemistry , 3rd e d. , W i l e y 6 S o n s , N e w Y o r k , 1 9 8 5: 1 3. D I M M E L , D.R. A N D S H E P A R D . D . T e c h n o 1 2: 7 3 ( 1 9 8 2). - 582 3 J Wood Chem 1 7% a l c o h o l p u l p s w i t h e v e r y s e q u e n c e s t u d i e d. treatments a p p l i c a t i o n s. work (1 ) has Previous shown the feasibility of producing good quality technical organosolv hardwood pulps using pulping t e c h n o l o g y: the Alcohol Pulping and Recovery (APR) P r o c e s s. Fibers produced by bleachable - - - successfu l ly process , have hardwood chemical pu lp pilot paper furnish in - low environmenta l impac t low capital cost , this an replaced the of the trials for component machine t i s s u e a n d w r i t i n g g r a d e s. Previous reports have compared APR pulps pro pilot conventional with level - duced at pulps produced on an study APR Process alcohol pulps and kraft pulps produced of the on USA, were chemical pilot a the composition and numbers AND the APR 1.2 yield screened to 2 0 5 0Z - lower than that alcohol pulp residual b l e a c h c h e m i c a l s t h a n k r a f t. This reactivity readily than kraft ^ numbers were treated with the same subsequent num . ie r of bleaching Consumption b r i g h t n e s s. higher The always brighter thus be kappa alcohol pulps were t h a n k r a f t. A l c o h o l p u l p s c a n bleached to brightness equal l o w e r o p e r a t i n g c o s t (l o w e r ( f e w e r s t a g e s) a n d c h e m i c a l c o n s u m p t i o n ). Table 1 BLEACHED PULP BRIGHTNESS (R a n g e s f o r e a c h pulp t y p e for a l l i n i t i a l c h e m i c a l c h a r g e s) Bleach Sequence Alcoho 1 Kraft - 85.5 - 90.0 86.5 - 88.5 - 78.8 81.6 CDED CdEDED - 86.0 87.0 - 88.0 88.0 D ED 85.0 - 87.8 86.5 terms or an of 87.0 - 90.5 - 89.5 87.8 - 90.2 82.2 - 89.2 a Saccharide analyses show that both bleached points much at scale with lower capital investment .c o m m e r c i a l more either chemical alcohol unbleached conditions these on contained , lignin a - b a s i s , 88 89 * g l u c a n , a s c o m p a r e d k r a f t. tor Xylan was much m kraft pulps, ( 1 6 1 9Z ) - than in alcohol (8.4 9.4:) slightly higher show that a lt ho u gh mannan is levels were reached for p u l p s. This di f ference in - 8 1 8 2* higher - free with eq u i v a l e n t Table under produced pulps in data brightness or C E CE bleaching st ages ac h i e v e to condit ions, bleaching - comparable with 89.0 percentage in pulps - 89.0 with s t a g e s. bleaching subsequent al l throughout maintained is 87.5 b leflc 'ied pulps enhanced CEDED pulp indicates lignin reacts much strength, produced were This more readily with and pulps k r a f t. yield , kappa that alkaline extraction CED h i g h e r t h a n k r a f t. Alcohol first Wisconsin , equal . fact of At l 7 the - 87.0 83.8 - 85.5 to process by 86.0 response DISCUSSION bleaching CE HD s e q u e n c e s. REJ5 U LTS to batch single than response 75.6 state for c o m pa r e d In this ( C E D) CEH from a scale from chips aspen i n d u s t r i a l s c a l e. DE D E D. were When INTRODUCTION after numbers kappa Alcohol pulps produced from aspen ABSTRACT wood at the pilot level had higher yields than using seven different When bleached k r a f t. sequences they consistently produced brighter chemical lower with stages fewer in pulps had pulp alcohol Bleached c o n s u m p t i o n. strength properties equivalent to kraft at the Thus , alcohol pulps are a b r i g h t n e s s. same suitable replacement for kraft in paperraaking stages ^ The superiority exemplified is three brighter C pu Ip alcohol of Biological Energy Corporation 2650 Eisenhower Avenue 19482 Valley Forge, PA in bleached or or CEDED by kraft J . H . L O R A , M. C R O N L U N D , J . P O W E R S , C. O R L O W S K I a n d L. W U (C E D ) bright as AND KRAFT PULPS pulps alcohol fact , A COMPARATIVE STUDY OF ORCANOSOLV In in alcohol carbohydrate composition of terms can - peeling off in readily be explained in the carbohydrate difference the degradation most mechanism ln r e a c t i o n) vs (a c i d alcohol h y d r o l y s i s ) p u I p i n g. Alc oho1 similar pu 1 ps to had strength propertles kraft since equivalent tear tensile at kraft 2/ pulps m N.m of g had each tear other p u l p s. unbleached higher breaking equal Thus , - were 62 792 of kraft and 74 822 at - 24 18 8.1 7.5 7.0 8.3 B u r s t i n d e x , k P a.m / g ^ 3.0 2.9 3.0 3.2 Breaking length, km 5.3 5.2 6.1 5.8 V i s c o s i t y , m P a.s 30.9 22.8 Relative refining time 4.2 within 1 0 both bleached and bleached pitlps had inferred when followed of pulp 18 indices than properties 24 and unbleached at Beatability lower unbleached 27.3 23.7 1.8 1.3 pu 1 ps , as 1.0 . c o m p a r e d a t t h e s a m e b r e a k i n g l e n g t h. Strength O r i g i n a l k a p p a n o. , m L / g 2 T e a r i n d e x , m N.m / g alcohol Both Kraft Alcohol lengths for indices tear - f o r b o t h p r o c e s s e s. relationships were obtained 3 B L E A C H E D P U L P P R O P E R T I E S A T 1 . 5 0 c m /g B U L K (a 1 k a 1 i n e kraf t . Table 3 unbleached of from o r d e r: the kappa lower > kraft alcohol h i g h e r k a p p a a l c o h o l. 2 4 m L / g k a p p a n o. s a m e a f t e r b l e a c h i n g. 1 8 m L / g k a p p a n o. (T a b l e 2) w h e n 3 c o m p a r e d a t 1 . 5 0 c m / g b u l k. CONCLUSIONS Process Table 2 They UNBLEACHED PULP PROPERTIES obtained high to kappa times, alcohol > kraft > This order remained the pulps in from with favorably compared bleached kappa higher Alcohol were refining re1at ive kraft higher brightness the APR p u l p s. yields and with less levels 3 AT 1.50 cm g /gm BULK c h e m i c a 1s Alcohol K a p p a N o. , m L / g Kraft p u l p s. and fewer in Whi le stages unbleached than alcohol kraft pulps had 24 18 24 18 strength below kraft , bleached T e a r I n d e x , m N.m / g 5.7 6.1 7.2 7.8 samples were comparable and in some instances B u r s t I n d e x , k P a .i n 2 / g 2.9 3.1 4.7 4.2 easier Breaking lengths , km 5.6 6.7 8.2 _ 8.2 alcohol V i s c o s i t y , m P a. s 29.4 29.2 49.0 36.7 replacement Relative refining time 9.0 2 1.0 3.6 2.6 properties to r e f i n e. pulps This exhibit study confirmed properties suitable that for of kraft pulps in pa permak ing J .H . and Aziz, S. "O r g a n o s o l v a p p l i c a t i o n s. REFERENCE Once for bleached alcohol properties of kraft C EDED D the _ two eliminated: of (by C ED D < 1) for k r a f t ), the p u l p i n g: types of when samples the c ompared , the within 152 n o. alcohol pulps were Thus alcohol . (T a b l e 3) were pulps was with kappa initial same brightness and difference between practically 88 to pulps, in spite of having lower unbleached strengths than / raft , produced physical bleached properties , pulps with comparable probably because lower chemical charges and fewer stages were required . to achieve the same target brightness 182 Lora, a versat i le approach r e f i n i n g " T a p p i J . , i n p r e s s. to wood - Enrichment of barks with single cell proteins : Seme fungi nave been known for years to be capable of growth on ba: extract or acid hydrolyzed bark , e.g Phanerochaete chr sosporium , Aspergillus niger and A. . BIOTECHNOLOGICAL METHODS FOR VALORIZATION OF BARK WASTES fumigatus , PeniciIlium sp. and Candida tropicalis. A .M. DESCHAMPS These fungi ( cited in ref . 1) gave generally poor yields . of proteins except for C tropicalis which was found to degrade pine tannins as well as some of our yeast strains isolated from barks ( 11) The bioconversion of bark to UNIVERSITE DE TECHNOLOG IE DIVISION PROCEDES BIOTECHNOLOGIQUES B P 233 60206 COMPIEGNE FRANCE . .. SCP patented in Canada by Daugulis and Bone ( 3 ) needs , before industrial applications , to solve the standard problems associated with lignocellulosics and to use ABSTRACT - strains adapted to tannins or , preferably , degrading Barks and bark wastes may be valorized by several these polyphenolics non biotechnological methods, but are frequently burnt or discarded . Today new processes can be developed using microoganisms to detoxify or convert barks into valuable products. Due to the specific biochemical composition of barks , only selected strains or populations can be used in such processes . Results obtained during personal experi - ments and found in the literature show that barks should new be considered as valuable lignocellulosic substrates . Biodegradation of tannins : Depending on their variable structure ( 10 ) tannins are generally considered as resistant to biodegradation Hydrolyzable tannins . ( also named gallotannins ) have been known for sixty years to be degradable by fungi and more recently by yeasts ( for references see 9 ) . Condensed tannins , which are the most widespread in plants and . especially in coniferous barks , are very recalcitrant to biodegrada tion . KEYWORDS: Bark , Valorization , Biotechnological Processes as chestnut tannin imroDucTiON - Bark remains today a lew value waste product from the . wood and pulping industries in many countries In France to use part of these barks in different processes . They are used in horticulture to preserve soil or peat moisture or for decoration and also as a substrate to grew orchids . The barks may also be heated and pressed to obtain fuel grade briquettes with or without a preliminary fermentation . - Small amounts of bark are seme times incorporated into part icleboard by some manufacturers , depending on the species - barks in cattle feeding were unsuccessful because of the lew proportion of bark allowed in the diet. The train reason why barks are such a problematic substrate is their richness in simple and polymerised phenolic compounds , especially tannins , known for a long time as inhibitors of enzymes a nr ] growth for most microorganisms. The phenol ics may be easily extracted from barks with hot water or alcohol and could be used in the preparation of adhesives in particleboard manufacture Some authors report positive result ( 2 ) but a controversy remains on this valorization In addition to the phenolic fraction , barks contain a lot . . - of water soluble sugars and * lso typical lignocellulosic polymers (cellulose , henucelluloses, lignin ) but their ed because of the antimicrobial components , Hcwever seme processes have been developed taking into consideration the particular biochemical composition of this substrate . These tannins are biodegraded into gallic acid , which accumulates in the cultures before being utilized by the extracts containing only gallotannins . We demonstrated also recently the degradation of condensed tannins ( wattle and quebracho ) by different bacterial strains ( 4 ) and also by different species of yeasts ( 6 11) # . The bacteria are better degraders but the yeasts could be - used at the same time for protein production and enrich . These original results prove that microorganisms ment can degrade or convert tannins as well as the other lig . Some recent attempts to incorporate utilization in biotechnological processes has been neglect and produce a tannase activity . This property could be used for the production of gallic acid ( 5 ) from tannins or from homogeneous bark . Some methods have however been suggested of wood utilized (9) bacteria . and most parts of Europe the barks are dumped or burnt when possible . We isolated some years ago a collection of bacterial strains able to degrade tannic acid as well nocellulosic oorrponents . Biodegradation and bioconversion of bark extracts: Baik extracts can support the grewth of adapted populations of microorganisms ( 8 ) such as the tannindegraders reported above , Tannins in extracts of pure , - oak and gaboon wood barks were degraded as well as contnercial or purified tannins ( 6 and Descluinps and . . Leulliette , Phvtopathol . 2 , in press ) These bacteria or yeasts can utilize at the same tune the other soluble components. Sane strains with no particular ability to degrade phenolics , but able to grow in the presence ot nonphenolics Both the increase of the phenolic content and removal of sugars give a more reactive extract for protannins , have been used to decrease the amount of - . paration of adhesives ( 1 2 ) . Fast growing strains in - continuous cultures could be useful for continuous pro - duction of such a highly reactiw extract . 183 V 8 - . Controlled solid fermentation or composting of bark chips: Composting of barks has proved to be difficult be - cause of bark antimicrobial compounds such as tannins (13), so barks are frequently mixed (20 to 40% as bark) with different agro industrial or municipal wastes. This proportion and the long incubation time mean that only a limited fraction of the industrial bark wastes can be used this way. Sometimes tannins must be extracted after or before composting to obtain a non toxic product for horticultural or agricultural uses (14). We showed same years ago that barks can be degraded by mixed bacterial cultures (7) in a liquid fermentation at controlled temperature to obtain degradation of lignin, cellulose and tannins. Pure cultures degraded tannins and cellulose only. These results were confirmed in solid state cultures (to be published) carried out in a rotating drum fermentor at 39 'C with a high moisture level and neutral pH using mixed cultures of an Aeramonas sp. and Gram positive bacteria such as Cellulomonas sp., Corynebacterium sp. and Bacillus polymyxa. In such controlled but non sterile conditions tannins were degraded up to 95% in less than one day, no fungal contamination was observed. After 15 to 20 days depending of the mixed cultures liqnin was - - DESOiAMPS, A.M., MAHOUDEAU, G., LEULLIE7TE, L LEBEAULT, L. Rev. Eool. Biol. Sol 17: 577 5Qf - (1980) 9. DESOiAMPS, A.M., OTUK , G., LEBEAULT, J.M. J. of Ferment. Technol. 61: 55 59 (1983) 10 . HASLAM , E. in: Biochemistry of plant PHENOLICR 475 523. New York: Plenum Press (1979) OTUK , G., DESOIAMPS, A.M. Mycopathologia 83: 107‘ t *. * 111 (1983) •4 SCHMIDT, O., AYIA, C., WEISSMANN, G. Holz Roh. > Werkstoff 42: 287 292 (1984) - - 11. « 4 • 12. - 13. SMITH, J.E., PATERSON, R.R.M. Process Biochem. July August: 41 48 (1976) 14. SOLBRAA, K• SANT, M.D., SELMER OLSEN, A.R., GISLEROD, H.R. Biocycle 24: 44 48 (1983) - - t - - - » A.. % - •* NOTE: Author's present address: National Research Council Plant Biotechnology Institute 110 Gymnasium Road Saskatoon, Saskatchewan S7N CW9 Canada . M e * highly degraded (40 to 55% of the initial content) when cellulose was weakly degraded (10 to 15%). These results shov*x3 that bacteria could be used in rapid processers for detoxification or longer processes for delignification of barks with better yields than fungi but in more expansive controlled conditions. l . ••a » v% v * CONCLUSION Barks may be considered today as a valuable substrate for biotechnological processes. The phenolic compounds can be degraded rapidly by bacteria or converted to use ful comjxxjnds. Detoxified barks may then be used in conventional processes for bicmass bioconversion. The biotechnological processes under investigation in several laboratories must pay attention to the unique composition of bark to obtain particular products such as simple phenolics or adhesives, r - REFERENCES 1. BRODERICK, J.B., SINCLAIR, E.B. Appl. Microbiol. Biotechnol. 20: 384 388 (1984) 2. CHEN, C.M. Forest Prod. J. 32: IM 18 (1982) 3. DAUGULIS, A.J., BONE, D.M. Canadian Patent 1.104.07 - - June 30 (1981) 4. - DESOiAMPS, A.M. Can. J. of Microbiol. 31: 499 502 ( 1985) 5. . DESOiAMPS, A.M , LEBEAULT, J .M. Biotechnol. Letters - 6: 237 242 (1984) 6. DESOiAMPS, A.M. LEULLIEITE, L. Intern. Biodeterior. - 20: 237 240 (1984) DESOiAMPS, A.M., MAHOUDEAU, G., LEBEAULT, J.M. Eur. J. Appl. Microbiol. Biotechnol. 13: 222 225 (1981) - 184 t , respectively. - END WISE DEGRADATION OF HYDROCELLULOSE IN MILDLY ALKALINE SOLUTIONS AND ITS RETARDATION BY AMMONIA (Has been published in J.Wood Chen. & Tech. 5(2):203(1985)) VINCENT L. CHIANG , ASSISTANT ROFESSOP MICHIGAN TECHNOLOGICAL UNIVERSITY INSTITUTE OF WOOD RESEARCH HOUGHTON , MI 49931 ^ RESULTS AND DISCUSSION Effect of nH on the Rate of Peelir. .* When data from peeling experiments conducted at 140°C in the pH range 9 to 11 were applied to eauation 1, it was found that L values were nearly unaffected by the pH of the experiment and satisfactory straight line relationships corres ponding to equation 1 were obtained (Figure 1). * - KYOSTI V. SARKANEN , PROFESSOR UNIVERSITY OF WASHINGTON COLLEGE OF FOREST RESOURCES , AR 10 SEATTLE, WA 98195 - ABSTRACT At 140 C and the pH range 11 to 9, the rate of end wise degradation (" peeling ") of hydrocellu lose declines bv a factor of 0.34 for every pH unit reduced. The peeling rate, however , is strongly retarded in this pH range by the presence of ammonia. The retardation is believed to be » caused by the formation of Schiff's bases durinq • the reaction. - - PH 10.2 .5 - - % PH 9.2 ®i 0 2 4 6 8 10 12 14 16 18 20 Time , min ^ I - KEYWORDS: End wise degradation (peelincr), Hydro - - cellulose, Ammonia. . Rate plots, based on equation 1 , for Figure 1 the hydrocellulose in three buffer solutions at 140 C. On this basis, the peeling rate constants were computed. When these values together with those from earlier studies on hvdrocellulose (1) and amvlose ( 3 ) were ploted , as percentages of the calculated peeling rate at pH 14 (1), against pHs , a common sigmoidal curve was obtained (Figure 2 , ° INTRODUCTION It is well known that the end wise degradation ("peeling ") of polysaccharides proceeds rapidly in alkaline solutions in the temperature range 100 to 130 C. The kinetics of this process have been extensively clarified for hydrocellulose (1 ), softwood glucomannan (2) and amylose (3) above pH 12, but no systematic studies have been per formed at lower alkalinities. Consequently , a studv was undertaken to clarify the kinetic pat tern of alkaline peelincr of hydrocellulose in the pH range 9 to 11 During the course of this studv it was found that ammonia exerts retarding influence on the rate of peeling in this pH range. This phenomenon was then subjected to a separate investigation. - ° - . curve 1). c* 100 o, 80 5 60 x £ 40 so 20 0 8 MATERIALS AND METHODS Buffer solutions (4) of pHs 9.2, 10.2, and 11.1 were used without dilution. Hydrocellulose was prepared according to Chiang and Sarkanen (5). Ail kinetic runs wore done in 45 ml auto claves heated in a rocking aluminum block heater (5 ). The rate constant ( kp) of peeling reaction was calculated according to equation 1 (1 , 3), - kp x t = Xn Ln L L* - - - .1 Eg L where Xn is the number average deqradable chain length (68 for hydrocellulose (6,7,8)) and L*o and L are the percent weight fractions lost due to peeling after prolonged reaction tine and time 9 10 11 12 13 PH 14 Figure 2. Curve 1: Propagation rate constants , expressed as percentages of the extra polated constant at pH 14 , shown as a function of pH. : Results based on earlier study by Haas et a l ( 1). : Present data. : Data extrapolated to 140 C for the peeling of amylose (3 ). Curve 2: Theoretical curve based on the observed inflection point of curve 1 . Curve 3: Data for the peeling of hvdrocellulose in presence of 0.8M NH 3. The observed decline in peeling rate at lower pH levels is in conformity with the proposition that the reaction species in peeling is the anion of the reducing end nroup, as has been proposed ( 3). The inflection point in the siumoidal curve in Figure 2, curve 1 is positioned at pH 11.7 - • ° _. - 185 - corresponding to the pK value for the ionization - of the reducing end group. The results suggest that the rate of peeling at lower pH range should be governde by the following expression: Rate of peeling =kp x [end qroup anion] Eq. 2 If the validity of equation 2 extends to pH values lower than 10, the anticipated rate of peeling can e estimated as a function of pH from the rate ob served at pH 11.0 and from the pK value 11.7. On this basis, expected values for log kp as a func tion of pH should conform with the straight line 2 in Figure 3. It can be seen that the experi mentally determined log kp values are signifi cantly higher than those predicted by line 1. - - - - - - - the comparison of respective peeling rate cons tants difficult. Effect of Ammonia on the Rate of Peeling It was observed that the presence of ammonium salts in mildly alkaline solutions retarded stronqly the rate of peeling as illustrated in Figure 5. When partially peeled hydrocellulose o 15 - 0 M NH 4 OH V, O tf> 0 19M 0.05 M 2 o 10 0.25 M 5 5 0.32 M a) 1 0 43 M $ 1 CL JC a> o 10 0 20 0 40 30 Time , min 50 60 Figure 5. -1 Effect of ammonia on the peelino of hydrocellulose at pH 10.2 and 140°C. samples were recovered after experiments illus trated in Figure 5 and subjected to a standard alkaline degradation , complete peeling was obser ved. Consequently , the presence of ammonia does not qenerate stabilized end groups but must nevertheless modify them in such a manner as to reduce the rate of peeling. In the pH ranqe 9 to 13 , more than 95 per cent reduction in peeling rate can he achieved by the addition of sufficient amounts of ammonium salts, as shown in Figure 6. In contrast, even large - -2 8 9 10 11 12 PH Figure 3. Log kp as a function of pH. Curve 1: Theoretical curve. Curve 2: Experimental values. The results indicate that the peeling rate , for some unknown reason , declines less than anticipa ted with a decrease in alkalinity and may still be significant in a neutral solution. The possibility prompted us to investigate the peeling process at pH 7. Two runs were conducted in a buffered solution at temperatures 140 and ° 170 C. The results are illustrated in Figure 4 and demonstrate that the initial rate of the peeling reaction is indeed significant at 140°and - - - 100 \ ° NX 80 p H 14 9 24 \0 o 2 60 ° 170 C 20 x *0 * 16 o E r 12 o o 40 ^ 8 Z 1« 0 C + REFERENCES ” " Interscience Publishers, p. 567 ( 1966 ) 10. SYKES, P. In: A guide book to mechanism London: Loqnman in organic chemistry Group Limited , P 215 ( 1977 ) .6 . NH 3 cone , M Figure 7. Empirical relationship between Ln kp/ ' and the concentration of ammonia kp'and kp are the rate constants of peelinq reaction with and without the presence of ammonia , respectively predicting the effect of ammonia on peelinq kn . . especially since data for pH 11 suggest the cor relations to reasonably independent of the reaction temperature. . 11. CHIANG, V.L • » CHO, P • and SARKANEN, K.V. 9 Kra t delignification of NH and H 2S nretreated hemlock, ( will be published in Pan puu , 1985 ) ^ ^ 12. KONDO, R. and SAPKANEN , K.V. Kinetics of lignin and hemicellulose dissolution during the initial stage of alkaline pulpino Holzforschung 38: 31 - 36 ( 1934 ) . . 13. DeHAAS, G.G and LANG, C.J. Delignification with ketones and ammonia. Taopi 57( 5 ): 127 130 ( 1974 ) - CONCLUSION Studies carried out by Chianq et ajL.( ll ) and Kondo and Sarkanen ( 12 ) in this laboratory sug gest strongly that the peeling of qlucomannans in softwood parallels that of hydrocellulose , Therefore significant henicellulose losses can be expected to occur whenever wood is pulped under near- neutra 1 conditions It was also observed that ammonia retarded the peelinq of glucomannan as it did that of hydrocellulose. Some of the observations reported in the literature can probably be credited to these retardation effects. For example, when DeHaas and Lang ( 13 ) pulped softwood chips at 200°C, using a combination of ammonia and aqueous acetone , nearly 90 per cent of the original glucomannan was recovered undegraded in the pulp. . 187 degraded WOOD CHEMISTR Y FOR FUN AND PROFIT D .A . I PAPRICAN PULP AND PAPER CENTRE UNIVERSI TY OF BRITISH COLUMBIA 2385 EAST MALL VANCOUV ER B . C . V6T 1W5 . . . industry , scientists have been l a i d o f f i n d r o v e s Government laboratori es are b e i n g " p r i v a t i z e d " Even i n t h e u n i v e r s i t i e s , tenure i s q u e s t i o n e d . . that research is a cushy job . . Ashok V i j h ( 1 ) p o i n t s out t h a t a s c i e n t i s t ' s - work l i f e i s f u l l of c o n f l i c t s " t h a t t e n d to c r e a t e deep psychologica 1 stresses with profound ramifications" . . I t i s a wonder we don ' t go b e r s e r k more o f t e n Why , t h e n , do we s t i c k w i t h t h e r e s e a r c h game 7 Because i t i s fun ! I b e l i e v e t h a t we e n d u r e t h e f r u s t r a t i o n , t h e conflicts and the basic uncertainties of the s c i e n t i f i c l i f e b e c a u s e we e n j o y i t It is challengin g It i s e x c i t i n g And when a s c i e n t i s t . . . f i n d s i n a l l t h e u n t i d y unknown one c l e a r , small gem of new knowledge , science becomes t o h e r or him completely satisfying If r e s e a r c h ceases t o be fun , i t ceases t o be research By d e f i n i t i o n , t h e r e f o r e , r e s e a r c h in wood . . c h e m i s t r y must questions in be my fun . own field , Here days . A large present program falls in tMs is of 4 great proportion area . 4 of chemical q u e s t i o n s s p r i n g up around processes now c u r r e n t i n t h e p u l p and paper are some of t h e fun which may be loosely described as t h e m o l e c u l a r a r c h i t e c t u r e of wood : - Why does t h e chemical s t r u c t u r e of l i g n i n d i f f e r - i n d i f f e r e n t r e g i o n s of t h e wood ? Are Ata 11 a and Agarwal ( 2 ) c o r r e c t ? Is l i g n i n oriented in the cell wall ? Does a d s o r p t i o n of - t h e l i g n i n monomers onto t h e c a r b o h y d r a t e s u r f a c e c o n t r i b u t e to t h e o r i e n t a t i o n of t h e polymer ? Are t h e structures of t h e hemicel 1 u l o s e d i f f e r e n t i n d i f f e r e n t p a r t s of t h e c e l l wall ? How are hemicel 1 u l o s e molecules o r i e n t e d w i t h r e s p e c t t o cellulose microfibrils ? What i s t h e d i r e c t i o n of c e l l u l o s e c h a i n s in t he microfibri 1 ? Does c h a i n d i r e c t i o n a f f e c t t h e p r o p e r t i e s of p u l p s ? Of course we may e x t e n d t h i s l i s t c o n s i d e r a b l y Then t h e r e a r e t h e bushels of q u e s t i o n s on how wood i s p r o d u c e d i n n a t u r e a n d t h e way i t i s - . In s p i t e of t h e d e d i c a t e d work of o r g a n i c c h e m i s t s on t h e chemical pulping of wood and i t s s u b s e q u e n t b l e a c h i n g , we have much to l e a r n in t h e s e And h e r e may I make a p l e a , a reas In t h e i i n t r o d u c t i o n t o t h e i r e x c e l l e n t book , Fengel and Wegener ( 3 ) p o i n t out t h a t " The c h e m i s t r y of wood and i t s c o m p o n e n t s cannot b e regarded a p a r t from i t s s t r u c t u r e , Wood i s m e r e , l y a chemical s u b s t a n c e o r an anatomical not tissue , or a material i t i s a combination of | all three T h i s e n t i r e l y r e s u l t s from an i n t i m a t e a s s o c i a t i o n of t h e chemical components w h i c h form u l t r a s t r u c t u r a l e l e m e n t s , b e i n g combined i n t o h i g h e r o r d e r systems which i n t u r n . b u i l d u p t h e w a l l s of t h e c e l l s t h a t u l t i m a t e l y industry What makes s c i e n t i s t s do r e s e a r c h ? I t i s c e r t a i n l y not t h e t h o u g h t of g e t t i n g r i c h N e i t h e r can 1 t be j o b s e c u r i t y , In North American be wood these the May we b e g i n w i t h a q u e s t i o n it of interest Myriads . Hardly biochenistry The of t h e Indeed , t h e p r e s t i g o u s W a l l e n b e r g P r i z e h a s been awarded t h i s y e a r t o two o f our l e a d e r s i n t h e b i o d e g r a d a t i o n o f wood . GORING Could . . - . - . 4 compose t h e wood t i s s u e " We should t h i s in mind w h e n e v e r we d e s i g n i n t e r p r e t d a t a on t h e c h e m i c a l bear or experiments r e a c t i o n s i n woody m a t e r i a l s We question . are now ready . for the dollar 4 Who pays ? . course , i s s o c i e t y And i t pays a I t t a k e s a t l e a s t $ 100 , 000 p e r annum to k e e p each The answer , of . million lot p e r s o n in t h i s room g o i n g , On a global scale , t h i s could t o t a l hundreds of m i l l i o n s of d o l l a r s s p e n t on R & D r e l a t e d t o wood c h e m i s t r y , Will s o c i e t y p r o v i d e t h i s kind of s u p p o r t m e r e l y t o allow wood chemists t o have fun ? There must be p r o f i t The I think not . . r e s u l t s of our r e s e a r c h must have r e l e v a n c e t o s h o r t term and l o n g term needs of p e o p l e Here , of course , t h e f o r e s t i s very much i n a s c e n d e n c y i n p e o p l e ' s minds t o d a y , The o i l r u n n i n g out t h e f o r e s t s w i l l grow on f o r e v e r , us feed t h e world , h e a t t h e world and t r a n s p o r t world w i t h wood from our f o r e s t s Can we ? the . - the is £ Let the . - Can food from wood c o m p e t e w i t h food from grass . g r a i n s , v e g e t a b l e s and f r u i t ? But do not f o r g e t t h a t n a t u r e h a s d e s i g n e d wood t o be v e r y - Maybe , . indigestible A f t e r o i l , w i l l wood be a b l e t o compete w i t h coal over t h e n e x t millenium as t h e raw material f o r . 189 . bulk chemi cals ? Perhap s Althou gh the econo mics of such usage of wood contin ues to be negati ve - How about energy ? aircraf t - Can we develo p metho ds to bleach chem imech anica l . Can we run our autom obiles and fuels from wood ? I t is possib le - . on . hydrog en will order be And produc ed d i r e c t l y by which mimic , but are an of magnit ude more efficie nt than the the that wood is best used for what a structu ral materi al When all cheape r , effecti ve and benign to human s the traditi onal ly used compo unds such as ( unlike PCP and creoso te ) ? - Can we make the superio r adhes ives require d for and perman ence in the new compos ite lumbe r and flakeb oard ? - Have resear chers on the surfac e chemi stry of wood contrib uted a l l techno logy ? they can to paint and adhesi ve - Can we synthe size , by conve ntiona l chemis try , enzym e like compou nds ( synzym es " " ) which act on wood l i k e enzym e molec ules but are smalle r , less fragile and much less costly than their natura lly occurr ing - counter parts ? 190 today seems is probab ly energy from wood to increa se I ask . Fun. to be a rather the . used firewo od . for most efficie nt What are way we , you now to of as wood the efficie ncy of this return the with me to Of course , we must have releva nce i n mind when we plan our project s Of course , we must make a strong case for our resear ch to those i n our society who hold the purse strings Of course , we must , more and more , t e l l the people in simple langua ge what we are doing and why we are doing i t Howev er , at the end of the day , i t is the fun that counts Withou t the eleme nt of joy in resear ch , nothing will make i t worthw hile And ( dare I say this ! ) i t has seeme d to me after a l i f e of resear ch that i f we scient ists take care to find fun in our scienc e , the p r o f i t s take care of thems elves . . . . . . - - Can we find new preserv atives for wood which are what . Zobel ( 6) estima tes that 20- 50% of is May . . is beginn ing . I believ e that opport unities are greater than ever before Let me l i s t just a few : . curren t worldw ide usage ? . . there harves ted chemi sts , doing . streng th wood getting . - then Comb ustion photos ynthet ic pathwa ys in nature the suitab le lumbe r has been extrac ted from the tree and a l l the suitab le fragme nts have been made into produc ts such as waferb oard , the best use for what is l e f t is paper Then , for wastes from the forest , the sawmi ll , the plywoo d mill , the waferb oard mill and the paperm ill , there may be a hierar chy of uses which includ e food , chemi cals and energy, Note howev er that , as world deman d for wood increa ses , the use of " wastes " moves higher up the hierarc hy We are now seeing oriente d strand board made from poplar ( a " weed " specie s ? ) compe ting succes sfully with plywoo d On the horizo n are produc ts such as Paralla m ( TM ) paralle l strand lumbe r , a high quality materi al made from small sticks of wood , coated with glue and pressed togethe r (M) . In pulp and paper , the trend world wide is to make a higher propor tion of the wood into usable fibre, And indust ries based on the exploit ation of wastes at the lower end of the hierarc hy will gradu ally have less and less startin g materi al availa ble Where does a l l this leave " wood chemi stry for profit " ? valua ble simplis tic project proces ses My own view is nature design ed i t .. chemi cals ( e g steroi ds from the neutra l fracti on of tall oil ( 5 ) ) Remem ber , howev er , that trees use sunlig ht very ineffic iently Probab ly in the lifetim e of people in this room , fuels such as metha nol or photoc hemica l pulp to high and perman ent bright ness ? Can we mine our proces s wastes for REFER ENCE S . VIJH, A • Dicho tomies of creativ e scient ists. 1 • . News , Februa ry , 4 , 18 ( 1985 ) . 2 . ATALL A , R. H. and AGAR WAL , U. P • * Raman microp robe Canad ian Chem eviden ce for lignin orienta tion in the cell walls of native woody tissue Scienc e 227 , 636- 638 ( 1985 ) . . . . FENGEL , D. and WEGENER, G•• WOOD: Chemi stry , 3 . Walte r ultras tructu re , reactio ns . 5. 4 6 . . . de Gruyte r , Berlin, New York , 1984 p 4 A new produc t develo ped by MacMi llan . * Private comm unicat ion. KUTNE Y , J P • Bloed el Ltd . . ZOBE L , B • * The chang ing quality of the world wood . supply Wood Sci . Technol . , 1- 17 18 ( 1984 ) . and optical properties , Thus, in order to con trol the properties of these pulps it is neces SULPHITE TREATMENT OF ASPEN. FACTORS AFFECTING THE FORMATION 3F CARBOXYLATE AND SULPHONATE GROUPS R.P. Beatson, C. Heitner, M. Rivest and D. Atack Pulp and Paper Research Institute of Canada 570 St. John's Boulevard Pointe Claire, P.Q • * Canada H9R 3J9 ABSTRACT Populus tremuloides, woodmeal and chips have been treated to high yields, at 120 and 140°C , with sulphite solutions of pH 4 to 10 Aspen, and total S02 concentrations from 0.25 to 1.0 mol L~ l . At pH 7, the rate of sulphonation is proportional to the total SO? concentration and - the sites available for sulphonation ; it in creases by approximately 60 percent for each 10 *C temperature rise. The rate of sulphonation is fastest at high pH. The sulphonation of aspen lignin displays the same characteristics as the sulphonation of spruce lignin in all respects except one ; the maximum extent of sulphonation of aspen lignin is about 50 percent that of spruce. The dis tribution of sulphur in thin transverse sections of sulphonated aspen , as determined in a trans mission electron microscope , matches the pre viously reported distribution of the guaiacyl units. - - - These observations imply that only the guaiacyl units of aspen lignin are sulphonated and that the syringyl units bear very few free phenolic hydroxy groups. Carboxylate formation is promoted by high pH and temperature. It is little affected by total S02 concentration. Yield loss increases * B pH is increased from 4 to 10 and the effects ;w of changing total S02 concentration are small. » High total S02 concentration and a pH close to 7 are required for efficient production of high strength sulphite mechanical pulps from ' i 1 ® pen. - INTRODUCTION ;f Poplar is Canada ' 9 most abundant hardwood , *ePresent ing a volume of 0.79 billion m 3 ; about *0 P e r c e n t of this is represented by one *Pecies , Populus tremuloides [1 ]. A strong br 9ht chemimechanical pulp can be produced from *«Pen chips by treatment with sulphite solution on wed by refining [2 9]. In recent work [8] been shown that the acid content of these tt4“high yield aspen sulphite mechanical pulps * Jor factor in determining their strength ’ ‘ •° * > ^ - - - sary to have a good understanding of the factors controlling the rate and the extent of the formation of carboxylic and sulphonic acid groups during the sulphite pretreatment. The sulphonation of lignin during treatment of 2.5 mm thick pieces of aspen veneer with sodium sulphite solutions in the pH range 4.2 to . HOW 9.0 at 170 *C was studied by Marth [10] ever , because of the high temperature, long time to temperature and treatment times of 30 to 600 minutes , little information was obtained on the early stages of sulphonation , so important to Also, the effects of chemimechanical pulping. - changes in total S02 concentration and tempera ture on the sulphonation reaction were not investigated. It was apparent , as observed earlier by other researchers [11], that aspen lignin did not sulphonate to as high a degree as spruce lignin. The generation of carboxylate groups in aspen during sulphite treatment has not been studied owing , in part , to the lack of a con venient method of distinguishing carboxylate groups from sulphonate groups in such pulps. However , a new method based on conductometric titration now provides a convenient way of determining the content of carboxylate and sulphonate groups in pulp [12] . This paper describes a study of the effects of changes in total S02 concentration, tempera ture and pH , on the formation of sulphonate and carboxylate groups in aspen during sulphite treatment and the effects of these changes on the concomitant yield and lignin losses. The degree of sulphonation of lignin in different morphological regions of sulphite treated aspen is also reported. - - EXPERIMENTAL Preparation of Woodmeal An aspen log from Eastern Ontario was reduced to chips , the chips were dried at room temperature for eight days and then ground to woodmea 1 m a Wiley mill , The woodmeal was air dried and screened in a sieve shaker , the fraction passing 40 mesh but retained on the 60 mesh being collected , This woodmeal was allowed to dry further at room temperature to about 95 - w i i percent sol ids. Preparation of Sulphite Cooking Liquor 7 i Sulphite liquors with pH levels of 4, 6 and were prepared by dissolving the requisite amount of sodium metabisulphite in deionised 191 i I , SULPHITE TREATMENT OF ASPEN. FACTORS AFFECTING THE FORMATION J)F CARBOXYLATE AND SULPHONATE GROUPS R.P. Beatson , C. Heitner , M. Rivest and D. Atack Pulp and Paper Research Institute of Canada 570 St. John's Boulevard Pointe Claire, P.Q. , Canada H9R 3J9 and optical properties , Thus , in order to con trol the properties of these pulps it is neces sary to have a good understanding of the factor controlling the rate and the extent of th « formation of carboxylic and sulphonic acit groups during the sulphite pretreatment. The sulphonation of lignin during treatment of 2.5 mm thick pieces of aspen veneer with sodium sulphite solutions in the pH range 4.2 tc . How 9.0 at 170°C was studied by Marth [10] ever, because of the high temperature, long time to temperature and treatment times of 30 to 600 minutes , little information was obtained on the early stages of sulphonation , so important to Also, the effects of chemimechanica 1 pulping , changes in total S02 concentration and tempera ture on the sulphonation reaction were not investigated. It was apparent , as observed earlier by other researchers [11], that aspen lignin did not sulphonate to as high a degree as spruce lignin. The generation of carboxylate groups in aspen during sulphite treatment has not been studied owing , in part , to the lack of a con venient method of distinguishing carboxylate groups from sulphonate groups in such pulps. However , a new method based on conductometric titration now provides a convenient way of determining the content of carboxylate and sulphonate groups in pulp [12] . This paper describes a study of the effects of changes in total SO; concentration, tempera ture and pH , on the formation of sulphonate and carboxylate groups in aspen during sulphite treatment and the effects of these changes on the concomitant yield and lignin losses , The degree of sulphonation of lignin in different morphological regions of sulphite treated aspen is also reported . - ABSTRACT Populus tremuloides , woodmeal and chips have been treated to high yields, at 120 and 140°C, with sulphite solutions of pH 4 to 10 Aspen , and total S02 concentrations from 0.25 to 1.0 mol L~ l . At pH 7, the rate of sulphonation is proportional to the total S02 concentration and - for sulphonation; it in creases by approximately 60 percent for each 10 *C temperature rise. The rate of sulphonation is fastest at high pH. The sulphonation of aspen lignin displays the same characteristics as the sulphonation of spruce lignin in all respects except one ; the maximum extent of sulphonation of aspen lignin is about 50 percent that of spruce. The dis tribution of sulphur in thin transverse sections of sulphonated aspen , as determined in a trans mission electron microscope , matches the pre viously reported distribution of the guaiacyl units. These observations imply that only the guaiacyl units of aspen lignin are sulphonated and that the syringyl units bear very few free phenolic hydroxy groups. Carboxylate formation is promoted by high pH and temperature. It is little affected by r tota 1 , SO< concentration. Yield loss increases t * ; pH is increased from 4 to 10 and the effects . fb changing total SO^* concentration are small. High total S02 concentration and a pH close to 7 are required for efficient production of high strength sulphite mechanical pulps from tBpen. the sites available - - ° - : V ^INTRODUCTION 71 Poplar is Canada 's most abundant hardwood , Presenting a volume of 0.79 billion mJ ; about BO percent of this is represented by one Populus tremuloides [lj. A strong bri9 ht chernimechanica 1 pulp can be produced from •Pen chips by treatment with sulphite solution *011owed by refining [2 9]. In recent work [8] has been shown that the acid content of these high yield aspen sulphite mechanical pulps H jor factor in determining their strength ^ ' ^ l I - - - - - EXPERIMENTAL Preparation of Woodmeal An aspen log from Eastern Ontario was reduced to chips , the chips were dried at room temperature for eight days and then ground to woodmeal in a Wiley mill , The woodmeal was air dried and screened in a sieve shaker , the fraction passing 40 mesh but retained on the 60 mesh being collected. This woodmeal was allowed to dry further at room temperature to about 95 - percent solids. Preparation of Sulphite Cooking Liquor Sulphite liquors with pH levels of 4, 6 and were prepared by dissolving the requisite amount of sodium metabisulphite in deionised 7 ^ 191 water and adjusting the pH with a trace of S 02 to give pH 4, or with 4 mol L~l sodium hydroxide . to give pH 6 and 7 The liquor having pH of 10 was prepared from sodium sulphite and 4 mol L 1 sodium hydroxide. ” more sulphite was eluted as determined by a permanganate test. A few sticks were removed for use in preparation of thin sections, The remainder were used for chemical analysis , The acid insoluble and acid soluble lignin were deter - Sulphite Treatment of Aspen Woodmeal Aspen woodmeal, approximately 10 g o.d • t was transferred to a 250 ml stainless steel bomb and soaked for 1 hour at room temperature in 220 ml of cooking liquor. The bomb was immersed in preheated constant temperature bath , The liquor in the bomb reached temperature in ap proximately 18 minutes , After treating the * * aspen at 140 C or 120 C for predetermined times from 0 to 120 minut.es the bomb was removed from the bath and rapidly cooled , The treated wood meal was removed and washed with deionised water until no more sulphite was eluted as determined by a rapid Palmrose titration [13]. The pulp was filtered from the wash water , weighed and part of the pulp was dried at 105 *C to obtain the consistency necessary for calculation of the yield. The lignin content , acid insoluble and acid soluble, of the treated wood was determined by CPPA Technical Section standard method G 9 and TAPPI useful method UM 250 respectively. The carboxylic and sulphonic acid contents of the treated woodmeal were determined by con ductometric titration[l 2]. a mined by CPPA Technical Section standard method G9 and TAPPI useful method UM 250 respectively. The sulphur content was determined by CPPA Tech nical Section standard method G28. Yields of - the treatments were determined by parallel experiments. The results are shown in Table 1. - - - Sulphite Treatment of Aspen Sticks Aspen (Populus tremuloides) wood chips were broken into small sticks in a Waring Blendor. About 7.3 g O.D. of the disintegrated chips were fully soaked with water and then immersed for 24 h at room temperature in 220 mL of a pH 7 solu tion of 104 g L“ l of sodium bisulphite and 33.3 g L" 1 of sodium hydroxide The impregnated - . chips and sulphite liquor were placed in a 250 mL stainless steel bomb and immersed in an oil bath heated to 155 *C. After 13 minutes the contents of the bomb reached 120*C and cooking was continued at this temperature for known times. The bombs were cooled rapidly and the wood sticks removed The sticks were washed by repeated soaking in deionized water until no . Preparation of Thin Sections Small sticks (1.5 x 1.5 x 10 mm , R x T x L) of treated aspen were embedded in Vestopal , a polyester resin. The embedded specimens were - sectioned with a Porter Blum OT 2 ultramicrotome to give sections with a thickness of 0.15 urn. The sections were placed on a carbon grid having a single 1 ran hole bearing a collodion film which had been carbon coated . The mounted specimen was charging. again coated carbon reduce to Microscopic Analysis Sulphur contents in the middle lamella, fibre and vessel walls were determined with a Philips 400 transmission electron microscope coupled with an EDAX 9100/60 analyser The system was fitted with an anticontamination trap cooled with liquid nitrogen and a beryllium . tipped specimen holder to reduce background noise. The conditions used for analysis were: condenser aperture , 100 urn; no objective aper ture; no diffraction aperture; tilt angle of specimen holder towards the detector , 21 * ; accelerating voltage 100 keV ; spot size 0.2 or 0.4 pm, emission current 10 13 Under these conditions , the sulphur Ka X ray counts during a 50 or 100 s analysis were recorded. The counts for the sulphur line were determined by subtracting the background , as estimated from the counts at 2.12 and 3.16 keV , from the total counts in the window at 2.23 to 2.39 keV. The sulphur Ka counts were taken as the measure of sulphur concentration. - - - . Sulphur Content of Aspen Treated at 120*C with pH 7 Sulphite Solution having a Total SO Concentration of 1 mol L~l . Table 1 ' Treatment Time ( minutes at 12 C * C ) 13 70 240 Yield ( percent ) Lignin Content (percent ) Lignin Losses (percent O.D wood ) 94.7 88.4 21.8 21.3 0.8 0 10 1.3 3.5 0 19 0.30 85.6 Lignin content o( original wood: 192 19. 1 22.6 percent . Sulphur Content of Treated Wood . . water and adjusting the pH with a trace of S02 to give pH 4, or with 4 mol L i sodium hydroxide more sulphite was permanganate test . to give pH 6 and 7. few sticks were removed for use in preparation of thin sections , The remainder were used for chemical analysis , The acid insoluble and acid soluble lignin were deter mined by CPPA Technical Section standard method G9 and TAPPI useful method UM 250 respectively. The sulphur content was determined by CPPA Tech nical Section standard method G 28. Yields of the treatments were determined by parallel experiments. The results are shown in Table 1. - The liquor having pH of 10 was prepared from sodium sulphite and 4 mol L“ l sodium hydroxide. Sulphite Treatment of Aspen Woodmeal Aspen woodmeal , approximately 10 g o.d • • was transferred to a 250 ml stainless steel bomb and soaked for 1 hour at room temperature in 220 ml of cooking liquor. The bomb was immersed in a preheated constant temperature bath , The liquor in the bomb reached temperature in ap proximately 18 minutes. After treating the aspen at 140 C or 120°C for predetermined times from 0 to 120 minutes the bomb was removed from the bath and rapidly cooled , The treated wood meal was removed and washed with deionised water until no more sulphite was eluted as determined by a rapid Palmrose titration [13] . The pulp was filtered from the wash water, weighed and part of the pulp was dried at 105 *C to obtain the consistency necessary for calculation of the yield. The lignin content , acid insoluble and acid soluble, of the treated wood was determined by CPPA Technical Section standard method G 9 and TAPPI useful method UM 250 respectively. The carboxylic and sulphonic acid contents of the treated woodmeal were determined by con ductometric titration[l 2] . eluted as determined by a A - - - # - - Sulphite Treatment of Aspen Sticks Aspen (Populus tremuloides) wood chips were broken into small sticks in a Waring Blendor. About 7.3 g O.D. of the disintegrated chips were fully soaked with water and then immersed for 24 h at room temperature in 220 mL of a pH 7 solu tion of 104 g L“l of sodium bisulphite and 33.3 g L” 1 of sodium hydroxide. The impregnated chips and sulphite liquor were placed in a 250 mL stainless steel bomb and immersed in an oil bath heated to 155 *C. After 13 minutes the contents of the bomb reached 120*C and cooking was continued at this temperature for known times. The bombs were cooled rapidly and the wood sticks removed. The sticks were washed by repeated soaking in deionized water until no - Table 1. Preparation of Thin Sections Small sticks (1.5 x 1.5 x 10 mm , R x T x L ) of treated aspen were embedded in Vestopal , a polyester resin , The embedded specimens were sectioned with a Porter Blum NTT 2 ul traniicrotome to give sections with a thickness of 0.15 urn. The sections were placed on a carbon grid having a single 1 mn hole bearing a collodion film which had been carbon coated . The mounted specimen was again carbon coated to reduce - charging. Microscopic Analysis Sulphur contents in the middle lamella, fibre and vessel walls were determined with a Philips 400 transmission electron microscope coupled with an EDAX 9100/60 analyser , The system was fitted with an anticontamination trap cooled with liquid nitrogen and a beryllium tipped specimen holder to reduce background noise. The conditions used for ar.alysis were: condenser aperture , 100 urn; no objective aper ture; no diffraction aperture; tilt angle of specimen holder towards the detector , 21 ; accelerating voltage 100 keV ; spot size 0.2 or 0.4 iim , emission current 10 13 nA. Under these conditions , the sulphur Ka X ray counts during a 50 or 100 s analysis were recorded , The counts for the sulphur Ka line were determined by subtracting the background , as estimated from the counts at 2.12 and 3.16 keV , from the total counts in the window at 2.23 to 2.39 keV. The sulphur K(1 counts were taken as the measure of sulphur concentration. - # - - Sulphur Content of Aspen Treated at 120*C with pH 7 Sulphite Solution having a Total SO. Concentration of 1 mol L~ l . Treatment Time Yield ( minutes at 120 * C ) ( percent ) Lignin Content ( percent ) Lignin Losses (percent O.D. wood ) Sulphur Content of Treated Wood 13 70 240 94.7 88.4 85.6 21.8 21.3 19. 1 0.8 1.3 3. 5 0 19 0.30 Lignin content ol original wood ; 192 22.6 percent . . 0 10 The ratio of sulphur concentration in the cell corner to that in the centre of an adjacent cell wall was determined by alternating the measurements between the two regions. Using Table 2. - so 2 - adjacent areas minimises errors caused by varia tions in section thickness, alternating the region of analysis reduced errors arising from variations in microscope conditions. The ratio was determined 14 to 16 times to give a reason Lignin Content (percent) Time at Temp, ( minutes ) pH 10 7 6 4 o 20. 7 IQ 21.1 19.9 19.2 20.9 19.6 21.2 30 40 60 90 100 120 able precision of the mean value. It was assum ed that any sulphur mass loss occurred to an equal extent in each region and hence the ratio was independent of possible mass loss. 18.5 19.0 21.2 20. 5 21.4 20 . 6 21.0 20.0 21.0 18.8 18.7 18.2 4 18.0 Lignin content of untreated woodmeal 22.6 per cent - RESULTS AND DISCUSSION Yield of Treated Woodmeal As shown in Figure 1 , yield decreases rapidly in the initial stages of treatment , especially at high pH. The yield of treated woodmeal increases as pH is decreased from 10 to 4 ( Lignin Content (soluble + Klason ) of Woodmeal Treated at 140 *C with Sul phite Solutions 1 mol L~ l in Total At pH 7 changing the total S0 concentra ? tion from 1.0 to 0.5 mol L"1 had no effect on the rate of yield decrease or the rate of lignini removal , as shown in Figures 2 and 3, but it - . does affect the rate of sulphonation as shown in Figure 4. Thus, as was observed for spruce [16], the sulphonation reaction does not control 100 TOTAL S 02 the O - 1 mol L 1 rate of delignification during the early stages of sulphite treatment. The slightly lower rate of yield and lignin loss as the total SO. concentration is lowered to 0. 25 mol L“ l is probably a result of a drop in the pH of the liquor. The buffering capacity of the 0.25 mol L" 1 solution was insufficient to maintain constant pH during the initial stages of treatment. The room temperature pH of the liquor dropped from 7 to 6.7 during the first 10 minutes of treatment and as shown in Figure 1, the rate of yield loss is quite sensitive to pH changes in this range. fl pH 140 C 4 6 7 0 10 ^ ^ 70 0 40 80 120 TIME AT TEMPERATURE ( minutes ) TOTAL SOj ( mol L Figure 1 . 1.0 Yield loss increases with increasing pH, for treatments at 140 *C with a total SO, concentration of 1 mol 2 -. pH 7 100 WOODMEAL AT 140 C c u 0) - 90 [14 , 15]. WOODMEAL AT 120 C - WOODCHIPS AT 140 C 10 •- 10 0J a O UJ - 80 > 70 0 - - - A 0.5 V 0.25 L l Table 2 shows that the lignin content of the treated woodmeal drops by 1.5 percent during the rise to 140 * C. At pH 6 the lignin content of the treated woodmeal remains the same for further time at temperature. At higher and lower pH levels slightly more lignin than hemi cellulose is dissolved during the treatment at 140*C. Thus , the more rapid yield loss at high er pH reflects increased removal of both hemi cellulose and lignin with increasing alkali concentration. A large portion of the hemi cellulose loss is a result of base catalyse d hydrolysis of acetates and fatty acid esters ') 40 80 120 TIME AT TEMPERA TURE ( minutes ) Figure 2. Changing total S concentration has little effect on02 yield , Decreasing temperature decreases yield loss and wood chips give slightly lower yields than woodmeal. 19 Sulphonation of Aspen XJ o O 24 c O $ c o ' (mol L ) 1.0 140°C pH 7 20 o 1 UNTREATED WOODMEAL 22 o> As shown in Figure 4, for treatment of aspen woodmeal with 1 mol L" sodium sulphite solution at pH 7 and 140°C, the rate of sul phonation decreases as the reaction proceeds , with a plateau in the 6ulphonate content of 105 m mol kg"1 being achieved within 90 minutes. This plateau corresponds to 0. 34 percent sulphur on wood. Under similar conditions black spruce incorporated a maximum of 0. 78 percent sulphur on wood [16]. TOTAL S02 LIGNIN CONTENT OF A 0.5 V 0.25 18 0) 0) 16 14 a. O s Also, Figure 4 shows that the rate of sulphonation at pH 7 decreases with decreasing total S02 concentration , For small yield loss es , if the rate of sulphonation at pH 7 is proportional to the number of sites available for sulphonation and the total S0 concentra ? tion ; then the sulphonate content( S ) at a given 12 10 o 0 40 - 120 80 TIME AT TEMPERATURE ( minutes ) Figure 3 - - Changing the total S0-, concentration from 1.0 to 0.5 mol L"* has no effect on lignin losses. Lignin losses are slightly less at 0.25 mol L" . ( t ) can equation: time ' be s =s U) CD 130 DO where 140 C O - S E 110 E described by the following -- ° - S )e kt (S is the sulphonate content at the plateau ° is the sulphonate content at time S - 90 t = 0 h Z UJ Z o O - TOTAL S0? 70 UJ h (mol L’]) - < o 50 A a. V w 30 1 1.0 0.25 . constant 0 40 80 120 total S02 concentration increases the rate of sulphonation at 140 * C and pH 7. The lines are gener ated from regression fits to the data points - It is also shown in Figure 2 that yield losses decrease with a decrease in temperature from 140 C to 120 * C and wood chips give slightly lower yields than woodmeal. Table 3. Total SO. mol L" ' 1.0 0. 5 0.25 - error. Also the rate constant is close to the value of 4. 19 x 10"? L mol"1 min l previously reported for the sulphonation of black spruc e under similar conditions [17]. As can be seen - Increasing . from the R ? quite well. values , the data fit the equation The quality of the fit is illu strated in Figure 4, where the lines calcu lated from the equation are displayed along with the data points. - The Dependence of the Rate of Sulphonation on Total SO Concentration S* ' m mol kg" 107 107 107 2.7 - from the data at each total S 02 con centration is the same within experimental TIME AT TEMPERATURE ( minutes) Figure 4. parameters , incuding the rate constants and the R? values , shown in Table 3. The value of S® was fixed at 107 mmol kg i for total SO con 2 centrations of 0. 5 and 0. 25 mol L“ l The rate - 0.5 I 194 Fitting the data points to this equation by non linear least squares gives the values of the S~ S m mol kg" -° ' L mol"1 min" 49.4 t 3.3 53.5 2.5 64.9 2.6 3.60 0.67 3.62 t 0.38 3.94 t 0.49 k x 102 ' R2 0.979 0.938 0.919 The effects of pH changes on sulphonation are displayed in Figure 5. For sulphite treat ment at i 40 * C with solutions 1 mol L“l in total - so 2 , the rate of sulphonation is the same at pH - 7 and pH 10. Below pH 7 decreasing the pH caus es a reduction in the rate of sulphonation. Similar observations were made for the sulphona tion of black spruce [16] and are related to a lower concentration of the highly nucleophilic sulphite dianion at pH levels below 7. T u> 130 O E 110 E - t z LU h 90 Z- O O 70 i WOODMEAL 140 C UJ - h < o> nO 120 140 C O TOTAL S02 1 mol L- 1 CL E E • WOODCHIPS 140 Q 50 WOODMEAL 120 C X cn : 30 a 0 z UJ 40 80 120 TIME AT TEMPERATURE ( minutes ) h H Fiqure 6. 2 O U * i Woodmeal >od chips sulphonate at the same ture from J 44 toReducing the tempera 120°C decreases the rate of ** ' ) phonation . * ^ - 2 O 40 120 80 TIME AT TEMPERATURE ( minutes ) Figure 5. Increasing pH from 4 to 10 increases the rate of sulphonation at 140°C and a total S092 concentration of 1 mol L l . - Figure 6 and Table 4 show that reducing the temperature from 140*C to 120 C causes a reduc tion in the rate of sulphonation and also that the rates of sulphonation for woodmeal and well - # - impregnated chips are the same , The rate con stant for sulphonation increases by 60 percent for each 10 degrees centigrade rise in tempera ture , corresponding to an activation energy of 53.4 kJ mol 1 , a value which is very close to the value of 63 kJ mol 1 found for black spruce ;i 7]. - - * The sulphonation of aspen woodmeal displays < the same characteristic as the sulphonation of * black spruce in all aspects except one; the ' maximum extent of 'J 1 * ** Miation of aspen lignin is about 50 percent th c * Of 9pruce. Since black spruce lignin cont*i\ i * only guaiacyl units , these observations *#./0ngly imply that the guaiacyl component of lignin and not the syringyl component is o r»g sulphonated. This ** is especially so sine * * J aiacyl units constitute about 40 percent of lignin (see appendix ) and model compound 8. r iC. [18] imply that the rate and dependence *X. of sulphonation of syringyl lignin should : * Kxnewhat different to that of guaiacyl ligr•1 f Lack of sulphonation of syringyl lignin WO * » * *Iso account for the reported low yield vf v / ringaldehyde on the nitrobenzene oxidation vf H nt liquors from the 4 early stages of sulpo.v '^ * coking of aspen [10, 19] . - ~ ^ * ## * - 4 Table 4. The Dependence of the Rate of Sulphonation on Tempered *nd Wood Form Form . ~ -S° S m mol kg 1 m mol kg* 1 k x 10* L mol 1 irir;~ R2 140 120 140 107 2.7 103 «• 1.6 103 * 4.0 49.4 t 3.3 40.8 t 1.8 34.1 •: 5.6 3.60 C.L 2 32 3.53 * 1. 0.979 0.997 # Woodmeal Woodmea 1 Wood chips ~ Temp C * S * . * 4 0.931 195 I I I I I I i i The selective sulphonation of the guaiacyl units in aspen lignin is consistent with the results of the microscopic studies of sulphur distribution Table 5 compares the sulphur concentrations in the middle of the fibre wall , . vessel wall and cell corner. Results are given for aspen which had been treated for three dif ferent times at 120°C with pH 7 sulphite solu - tions 1 mol L“l in total SO . It is apparent ? that the sulphur concentration in S layer of ? the fibre wall is on average about 11 percent of that in the cell corner region of the middle lamella. The value of 11 percent is maximum since up to 50 percent of the low x ray counts - in the fibre wall may arise from background radiation. Thus, the sulphur content of the fibre wall may be as low as 5 percent of that in the cell corner. The sulphur concentrat ion in the vessel wall is much higher being about 33 percent of that in the cell corner . The distribution of sulphur between the cell corner and fibre wall is markedly differ ent to that found for black spruce sulphonate d under similar conditions [20]. In black spruce the concentration of sulphur in the fibre wall was about thirty percent of that in the cell corner. It is reasonable to assume that the dis tribution of lignin in aspen is similar to that in birch [21]. Using the data for birch , the relative sulphur contents of the lignin in each region can be calculated as shown in Table 5. The low content of sulphur in the fibre wall lignin relative to that in the cell corne r and vessel wall lignin, when combined with the observation that maximum extent of sulph onation of aspen lignin is only 50 percent that of black spruce lignin, indicates that the aspen has less reactive sites in its fibre wall lignin . It has been demonstrated previ ously , by u.v. microscopy [22], and fibre fractionation [23] that the syringyl moieties in hardwoods are located mainly in the fibre secon dary wall whereas the lignin in the cell corner and vessel walls [24] is composed mostly of guaiacyl units. - i Table 5. Morphological Reg ion l I Fibre s? ML 196 S2 the distribution of sulphur in aspen matches the distribution of guaiacyl residues providing further evidence that only the guaiacyl units are sulphonated. The proposal by Marth [10], that poor pene tration of sulphite liquor into the syringyl rich regions is the reason for the low level of syringyl sulphonation seems unlikely since well impregnated wood chips and woodmeal were found to sulphonate to the same degree at the same rate. The lack of sulphonation of the syrin gyl lignin may result from a low phenolic hydro xy content. If phenolic lignin units are the site of sulphonation at pH levels close to 7, as has been shown for black spruce [17], a low pheno lic hydroxy content in the syringyl moieties, which account for about 50 percent of aspen lignin, would explain the observation that the degree of sulphonation of aspen lignin is much lower than that of black spruce. Indeed , it has been shown [25] that lignin isolated from sweetgum has a phenolic hydroxy content about 67 percent lower than that of spruce and recent carbon 13 NMR studies [26] have shown that lignin in the hard woods beech , maple , oak and cherry also have a lower phenolic hydroxy content than softwood lignin. Thus , it is probable that this is also true of lignin in a6pen. lignin - - - Formation of Carboxylate Groups As shown in Figure 7, carboxylate groups are formed in aspen woodmeal on treatment at 140 *C with sulphite solutions 1 mol L” 1 in total SOj having pH levels in the range of 4 to 10. A maximum carboxylate content of around 160 m mol kg “ l is attained very rapidly at pH 10 during warm up. As the pH is reduced to 4 the rate of carboxylate formation decreases. It is apparent from Figure 8 that for sulphite treatments at pH 7 and 140 *C changing the total S 02 concentration from 1.0 to 0.5 mol L“ 1 has little effect on the generation of carboxylate groups. However the rate of formation of carboxylate groups slows on - reducing mol L” 1 the total . S02 Sulphur Content of Lignin in Morphological concentration to 0.25 Regions of Aspen Ratio of Sulphur Concentrations Ratio of Lignin Concentrations Ratio of Sulphur Contents of Lignin 1 9 1 4.5 1 2.0 3 1.4 2. 1 cc Vessel Thus , the formation of the carboxylate groups by base catalysed hydrolysis of carboxylic esters. Since extraction of the woodmeal with acetone prior to the treatment caused no reduction in E H Z ID H O O 140 the amount of carboxylate groups formed during sulphite treatment, it is apparent that there is 120 no significant contribution to the carboxylate content from hydrolysis of the fatty acid esters. Thus the carboxylates must be formed by the hydrolysis of the esters of 4 0 methyl D glucuronic acid which are present in the hemi ID H < > x 100 oc 80 o CO -- o O 4 maximum carboxylate content of 160 m corresponds closely to the uronic acid content of aspen which is estimated from data available in the literature to be 148 m mol kg"1 (see appendix). The carboxylate content of aspen woodmeal before treatment with sulphite The mol kg l < “ 0 40 120 80 TIME AT TEMPERA TURE ( minutes ) Figure 7. Carboxylate groups are formed most rapidly at pH 10, for treatments at 140 ® C and a total S02 concentration of 1 mol L"1 . 180 o> x o E E 160 £UJ 140 A* a/ / o o 120 &A A V. V TOTAL S02 - 100 \/^ 0 h ? j > x A V 5 UJ was about 88 m mol kg"1 . Thus about 45 per cent of the carboxylic acid groups in the aspen wood meal were esterified . This is slightly higher than a previously reported value of 36.4 percent [28]. - Figure 9 shows that , for treatment of aspen with sulphite solutions having pH 7 and 1 mol z CO - cellulose [27]. a c -- 140 C (mol L ') pH 7 1.0 A 0.5 V 0.25 80 L” 1 in total SO., , reduction in temperature from 140°C to 120°C reduces the rate of generation of carboxylate groups. Also Figure 9 shows that, at pH 7 and 140 * C, carboxylate groups are formed slightly more rapidly in woodmeal than in well impregnated wood chips. Thus the rate of hydrolysis of the esters is influenced to a small extent by penetration or diffusion of the liquor to the reactive site. This is a result < O 40 80 O) 120 TIME AT TEMPERA TURE ( minutes ) Figure 8. For treatments at 140°C and pH 7 carboxylate groups are formed at the same rate for total S0 concentra tions of 1.0 and 0.5 mol ? . Reduc tion of the total S concentration 02 to 0.25 mol L"1 reduces the rate of carboxylate formation. - The observed lower rate • ( 180 0 * of carboxyl ate concentr ation is Format ion as t h e total S0; lowered to 0.25 mol L"1 , like the lower yield loss , is probably a result of a drop in pH of . the cooking liquor since as shown in Figure 7, the rate of formation of carboxylate groups is e*tremely sensitive to pH changes in this range. The increasing rate of formation of carbox ylate groups with increasin g pH and the lack of effect of decreasing the total SO , concent ra tlon from 1.0 to 0.5 mol L~1 are consistent with - - x o E E 160 i 11 - 140 - h ID h o U 120 WOODMEAL 140 C WOODCHIPS 140 C ID h - 100 • WOODMEAL < > x 120 C O CO OC i 80 < O 0 40 80 120 TIME AT TEMPERA TURE ( minutes ) Figure 9 . For treatment at pH 7 , increasing the temperature increases the rate of carboxylate formation. At 140 "C and pH 7 the formation of carboxylate groups is slightly faster for wood meal than for well impregnated wood chips ^ - . 197 t of fast hydrolysis reaction leading to penetration or diffusion being involved in the rate limiting step. the - The results show that high total S 02 con centration promotes sulphonation without a detrimental effect on yield , Although increas ing temperature increases the rates of sulphona CONCLUSIONS Sulphite treatment of aspen sulphonates lignin and hydrolyses ester groups in the hemi cellulose to carboxylic acids, The rate of sulphonation of aspen lignin at pH 7 is propor - - tional to total S0? concentration and the number of sites available for sulphonation. It has a second order rate constant of 3.7 ± 0.3 x 10”? L mol” 1 min” 1 and an activation energy of 63.4 kJ mol”1 . The rate of sulphonation increases with increasing pH. In all these aspects the sul phonation of lignin in aspen behaves in the same manner as the sulphonation of lignin in black spruce. However , the extent of sulphonation of aspen lignin under these conditions is only 50 percent of that of spruce lignin. These obser vations imply that the guaiacyl and not the syringyl units of aspen lignin are sulphonated due to the fact that syringyl units have a very low phenolic hydroxy content. For aspen treated with sulphite at pH 7 and 120 C, the sulphur content of the lignin in the fibre wall was found to be about half of both that in the cell corner region of the middle lamella and that in the vessel wall. This dis tribution of sulphur matches the distribution of guaiacyl units confirming the conclusion that only guaiacyl units sulphonate in aspen lignin. The low degree of sulphonation of fibre wall lignin indicates that sulphonation at pH 7 is not an effective method of softening fibres Thus , sulphonation of aspen chips at pH 7 will not increase the bonded area and tensile strength of aspen chemimechanica 1 pulps. Carboxylate formation is favoured by high pH and arises mainly from hydrolysis of uronic acid esters in the hemicellulose. At pH 10 the maximum carboxylate content of 160 m mol kg"1 is achieved during the 18 minutes required to reach 140 *C • Total S0; concentration ha6 little effect on the generation of carboxylate groups . Yield losses are lowest at pH 4 and increase with increasing the pH to 10. Total S02 concentration has little effect on yield or lignin losses. At pH 7 and a total S 02 concentration of 1 mol L” 1 increasing temperature increase s the rates of sulphonation , carboxylate formatio n and yield losses. The rate of sulphonation increas es by 60 percent for each 10 degree centigrade rise in temperature between 120 and 140* C. - tion and carboxylate formation it lowers yield. Carboxylate formation is promoted by high pH but at the expense of much lower yields. - Thus in order to obtain aspen chemimechani - cal pulps that have high sulphonate and carbox ylate contents while maximizing yield , high total S02 concentration and a neutral pH should be used. A pH much below 7 will result in slow sulphonation and very slow carboxylate forma tion, whereas pH 10 causes rapid yield loss. - ACKNOWLEDGEMENTS wish to thank Drs. J.F. Revol and S. Saka for helpful discussions and Mr. N. Muradali for expert technical assistance. We - APPENDIX The methoxyl content of Populus tremuloides lignin is reported to be 1.44 OMe/C unit [29] . 9 The p hydroxybenzoate content is reported - . to be 10 percent [30] # Let the number of guaiacyl moieties per C 9 unit be a then there are 90 a syringyl moieties and a methoxyl balance gives; - - - a + 2(90 a ) «= 144 a 36 Thus aspen lignin contains about 40 percent of guaiacyl units. . - 198 Aspen is reported to contain 23 percent of 4 O methyl glucuronoxylan in which there are 9 parts of xylan to each part of uronic acid [26]. As the molecular weight of 4 O methyl glucuronic acid is 208 and that of xylan is 150 there are 1350 g of xylan to 208 g of uronic acid in aspen glucuronoxy 1 an. Thus the uronic acid content of aspen is about 3.1 percent or 148 m mol kg” 1 . -- -- 19. REFERENCES 1. CPPA reference tables (1981 ). 2. C.H. Chidester, J.F. Laundrie and E.L. Keller , Chemimechanica 1 Pulps from Various Softwoods and Hardwoods , Tappi 43 (10), 876 880 (1960). - 3. R.M. Dorland , D.A. Holder , R. A. Leask and J .W. McKinney, Laboratory Refining of Soft wood and Hardwood , Tappi 45 (4), 257 265 ( 1962 ). 4. C.A. Richardson , Ultrahigh Yield NSCM Pulp ing , Tappi 45 ( 12), 139A 142A ( 1962). 5. R. A. Leask , Chemimechanica 1 Pulps from Hardwoods , Tappi 51 ( 12 ), 117 A 120 A ( 1968). - . - - - - . C. Heitner and D. Atack , Ultra-high-yield 8 . pulping of Aspen effects of ion content Pulp and Paper Canada , 84( 11 ), T252 T 257 ( Nov. 1983). - 9. Z. Koran , S.N. Lo and J Valade , Strength Properties of Birch and Aspen Sulphite Pulps in the Yield Range of 77 94% , Pulp and Paper Canada 85 ( 2), 39 42 ( 1984 ). 23. . 24. K. E. Walter , J.M. Harkin and T. Ken * Kirk , Guaiacyl Lignin Associated with Vessels Aspen Callus Cultures, Physiol. Plant. in 31 , 140 143 (1974). ^ - 25. - ^ H M. Chang , E.B. Cowling , W. Brown , Com parative Studies on Cellulolytic Enzyme Lignin and Milled Wood Lignin of Sweetgum and Spruce , E. Adler and G. Miksche , Hoizforschung 29, 153 159 ( 1975). - - H.H. Nimz, D. Robert , 0. Faix and M. Nemr , Carbon 13 N.M.R. Spectra of Lignins , 8, Holzforschung 35, 16 (1981). Aspenwood Pulps Produced by Sulphite Bisulphite Cooking Liquor Systems , Tappi 42 (4), 301 307 (1959). - 27. C. Schuerch in "The Chemistry of Wood ", pl91 247, ed. B.L Browning , Interscience Publishers, J. Wiley & Sons (1963). 0.0. Lindgren and U. Saeden , Sulphonation and Dissolution of the Lignins of Mono cotyledons and Dicotyledons with Sulphite Solutions at pH 4 7, Svensk Papperstidning 54 , 795 799 ( 1951 ). 28. P.Y. Wang , H I.Bolker and C.B. Purves , Ammonolysis of Uronic Ester Groups in Birch Xylan, Tappi 50 (3), 123 124 (1967) - 0. Marth , Studies on the Lignin Fraction of - - S. Katz , R.P. Beatson and A.M. Scallan , The Determination of Strong and Weak Acidic Groups in Sulphite Pulps, Svensk Papper stidning 87 (6 ), R 48 R 53( 1984 ). . G V. Palmrose , A Mill Test for the Exact Determination of Combined Sulphur Dioxide , Paper Trade Journal 100 (3 ), 38 ( 1953) - - . . - 29. . Y. Musha and D.A.I. Goring , Distribution of Syringy 1 and Guaiacyl Moieties in Hardwoods as Indicated by Ultraviolet Microscopy , Wood Science and Technology 9, 45 (1975). -480 - - 13. - 71 74 26. - 12 - H L. Hardell , G.J , Leary , M. Stoll and U. Westermark , Variations in Lignin Structur in Defined Morphological Parts of Birch e Svensk Papperstidning , 83 ( 3 ), (1980). - 11. Y. Musha and D. A.I. Goring , Distribution of Synngyl and Guaiacyl Moieties in Hardwood as Indicated by Ultraviolet Microscopy s Wood Science and Technology , 9 , 45 , 53 ( 1975 ). - 4 . - 10. 22. Hoiz- Dis fl Deter - - . LeMathieu, Tappi R. Franzen and K. Li, Aspen CMP; A supple mentary mechanical pulp. In Preprints of CPPA Annual Meeting in Montreal Feb. 3 4, 1983, 69 B, 163 173. . B.J. Fergus and D.A.I Goring , The tribution of Lignin in Birch Wood as mined by Ultraviolet Microscopy , forschung 24, 118 124 ( 1970). C A. Richardson and J. R 48, 344 346 (June 1965). 7. 21. - - . R.P Beatson, C. Gancet and C. Heitner, Topochemist ry of Black Spruce Sulfonat The ion , Tappi Journal , 67 (3 ), 82 85 ( 1984). - - - 6. . - 20 . ^ J . E. Stone , A Study of the Lignin During a Neutral Sulphite Cook of Removal Asnen Tappi, 38, 60 612 (1955) 30. . . - D.C.C Smith , p Hydroxybenzoate Groups in the Lignin of Aspen (Populus tremula ), J. Chem. Soc * » 2347 2351 ( 1955 ). . 14. S A. Rydhoim in “Pulping Processes", Publ. Interscience, John Wiley and Sons, 1965. 15. D.B. Mutton in “Wood Extractives" , ed. W.E. Hillis, 1962. 16. R.P. Beatson , C. Heitner and D. Atack , Factors Affecting the Sulphonation of Spruce , J. of Pulp and Paper Science 10 ( 1 ), J 12 17 ( 1984 ). - 17. C. Heitner , R.P. Beatson and D. Atack , Factors Affecting the sulphonation of Eastern Black Spruce Chips, J. of Wood Chem. and Tech. 2 (2 ), 169 185 ( 1982 ). - 18. J . Janson and E. Sjdstrom , Note Concerning the Sulphonation Rates of Vaniliyl and Syrmgyi Alcohol , Acta Chem. Scand . 19 (2), 525 527 ( 1965). - 1 19% L E A C H I N G O F L I G N I N AND CARBOHYDRA TE F R O M CHEMIMECHA NICAL P U L P S . carbohydrate . . . CORINC J M. W I L L I S AND D A I size of longer P U L P AND P A P E R RESEARCH I N S T I T U T E O F CANADA , AND DEPARTMENT O F C H E M I S T R Y , M c G I L L U N I V E R S I T Y , MONTREAL , CANADA 17400, wag removed from the fibre a t . The molecular weights of leaching carbohydrate Increase from . The - yield cheralmechanlcal sulphite pulp fibres were suspended In water , both lignin and macromolecules The experimental procedure used for The leaching of this o n t h e m e t h o d d e v e l o p e d b y P a v l s £t . (1) . The concentration of l i g n i n In the leachate was measured using ultraviolet spectrophotometry . The carbohydrate content was determined using an orclnol colorimetric technique lignin both . The observed rate of leaching and carbohydrate _ . d e v e l o p e d p r e v i o u s l y b y C h o i et a l al fitted (2) a theory and Pavls e t . ( 1) for the diffusion of macromolecules through the - water swollen for wall , fibre lignin ^ For six hours and carbohydrate were 1 0"1 3 a n d 1 . 4 * 1 0"1 3 c m * s e c"1 , r e s p e c t i v e l y of 3.8 * . These values are several orders of magnitude lover than the free diffusion of This suggests , restrictions these macromolecules therefore , which hinder In solution that the the movement . Infrafibre of the macromolecules during leaching are an Important factor In the diffusion mechanism Leaching pulp were washing 20°C at In . f r o m 2 0 °C t o 9 0 °C lignin over a and period Indicated the Increasing size of .i pulp these as a function of temperature, Aa s h o w n I n P l g u r e 2 , f o r b o t h carbohydrate , the rate of leaching Increased markedly with temperature , Removal of lignin and carbohydrate was particularly pro ounced at temperatures exceeding 70 °C This effect was . attributed to the softening of the pulp as a result of the glass transition of the water saturated hemlcelluloses • For both leaching was lignin found and carbohydrate , the of rate to decrease with an Increase In pulp yield , and a decrease In the refining energy used to prepare the pulps , Measurements of the water retention values ( WRV ) o f these pulps were performed since such values give an Indication of the pore size of the fibre wall and as a result can be equated with fibre swelling . long the walls of lignin and carbohydrate from the pulp was also studied leaching , the average lntraflbre diffusion coefflcents calculated the the cell . ^ for as porous matrix of by the carbohydrate were leached out of the pulp, as shown In al the 11430 to 61330 and 6130 to decrease flbies , as a result of study was based from the diffusion coefficients during leaching was attributed to larger restrictions Imposed on the diffusing macromolecules ultra high . leached respectively, progressed Figure 1 related to an Increase In the the macromolecules lignin and to - . This times of found H3 A 2 A 7 When - 1.9 x 10“12 to 5.7 * KT1*4 an 2 sec 1 f o r l i g n i n a n d 2.8 x 10 “ 13 t o 4.4 x lO 1 ** c m - s e c ~ 1 f o r . For both lignin and carbohydrate . a polydlsperslty of diffusion coefficients , ranging from 7 A b> cn 5 £ 4 O <0 CO 3 5 2 Lignin 1 Carbohydrate 0 0 20 40 60 80 100 T ( C) Figure 2 . The variation with temperature of the quantities of leached lignin and carbohydrate, Figure l Wf. ( 3 6 0 ) , a f t e r 6 h o u r s o f washing chemlraechanlcal pulp. . Average quantities of lignin and carbohydrate In the wash liquid , . v e r s u s t i m e , t , a t 2 0*C Wf(t ), 201 direct correlation was found between the WRV and the « quantity of material leached from the pulps , as shown . of the practical use of this technique has yet to be determined . in Figure 3 for lignin The implications of these results are significant The swelling of the cell walls of the pulp fibres wa9 deemed therefore to be a dominant factor in the leaching process. A decrease in leaching was also observed for an Increase in the cationic strength of the wash water , probably as a result of fibre . These observations are in accordance with deswelling trends previously found between fibre swelling and . cationic strength (3) Pretreatment of pulp with formaldehyde and with respect to the newsprint industry. The total solids capable of being removed from the pulp , about 1Z of the fibre weight , does not represent a large • However , when papermachine systems are loss in yield . closed , the build up of these soluble materials ln thewhite water could lead to several problems including slower production rate6 and a poorer quality of newsprint produced. The results obtained indicate that conditions do exist whereby leaching and as a increasing the pH of the wash water were both found to result , material loss ln white water systems , can be decrease minimized. the leaching of lignin and carbohydrate , while decreasing the pH of the cooking liquor and the use of anthraqulnone in the pulping process increased REFERENCES the leaching of lignin but did not affect the leaching . of the carbohydrate The observed effects could be . 1 related either to crosslinking within the fibre or further degradation of the fibre wall The uae of polyethyleneoxide/ alura retention aid in the wash water GORING , D.A.I., Trans. Tech. Sect., CPPA , 7: . also caused the leaching of lignin and carbohydrate to decrease• In this case , leaching was probably Impeded as a result of having the pores on the fibre wail surfaces physically blocked by the polyethyleneoxide macromolecules Of the methods investigated to reduce . . FAVIS, B.D , CHOI, P.M.K., ADLER , P.M. and . TR 35 (1981) 2. . CHOI, P.M.K , YEAN , W.Q. and GORING, D.A.I., Trans Tech. Sect., CPPA , 2: 58 (1976). . . 3 . GRIGNON, J. and SCALLAN , A.M., J. Appl. Polya . Scl., 25: 2829 (1980) leaching , the most effective one was found to be the formaldehyde pretreatment. However , the feasibility 3 a, cn E 2 O 10 % are difficult to obtain with these network polymers unless strain building (toughening ) components are in corporated into the network structure. This has been explored by the addition of polyethyle ne glycol ( PEG) ( 7 ) and polybutadiene glycol ( PBD) (8). While PEG produces uniform networks up to 18% of total polyol content , PBD addit ion results in distinct phase separation at glycol contents of > 2%. The PEG miscibility can be explained by considering (a ) molecular compatibility between hydroxypropyl lignin and PEG , and ( b) the low molecular weight of both components. PBD conta i ning materials can best be described as lignin reinforced rubber polyurethanes (rubber polyu re thane as a continuous phase with lignin inclu sions ) and as rubber toughened lignin polyu re thane ( lignin polyurethane as continuous phase with rubber inclusions). The two types of pro ducts display a wide range of modulus properties and it is seen that different types of glycols added to the hydroxyalkyl lignin derivative afford an excellent control mechanism over modu lus , brittleness , rigidity , and toughness. - - - ular weight and molecular weight distributions , and in color. - - - 1 . Solubility : The synthesis of ligni n de rivatives with greatly improved solubility cha racteristics has been achieved by hydro ation with a variety of alkylene oxide xyalkyl - s ( 1 ,2). Hydroxyalkyl lignin derivatives are mater ials with single functionality (primary OH groups in case of ethylene oxide derivatives and secondary OH groups in case higher alkylene oxide s are used ) and with sharply reduced glass trans ition tempe ratures at degrees of substitution ranging between 1 and 2 ( 3). These derivatives have exhibited solubilities in excess of 20% in numer ous solvents ranging from methanol to THF , for lignins inclu ding milled wood lignin , kraft lignin , organosolv lignin , and steam explosion lignin. Molecular weights have not been found to be diminished by the chemical modification reaction. The signifi - - cant improvements in thermal and solubility cha - racteristics have been explained with increased free volume due to the alkylene oxide substituent. 2. Modulus ( brittleness) : Although - some li all hydroxy alkyl lignin derivatives exhibit melt flow cha racteristics when heated to above their glass transition , they fail collectively to produce acceptable structural materials by extrusion. This is due to their low molecular weights . Che mical crosslinking reactions with diisocyanates produce polyurethane networks the property of hich have been studied extensively in relation o chemical and polymer network effects ( 4 8). Where glass transition temperature was found to gnins with low molecular weight , and - - - - Other mechanisms of property control of hydro xypropyl lignin based polyurethanes have been explored as well. These include reductions of hydroxyl functionality of lignin prepolymers by chemical modification , and alkylene oxide chain extension. 3. Molecular weight and weight distributi on : nctly in their molecular weight and weight distributi on characteristics ( 9). Although no systematic stu dies have yet been completed on this issue , pre liminary tests indicate a modest positive effect of molecular weight on Young's modulus and ten sile strength. Broad molecular weight distr ibu tions were found to contribute to network non uniformity (5). Low molecular weight liqnin fractions unincorporated into the network were found to reinforce the network at low sol contents ( < 2% ) and to plasticize it at conte nts of > 2%. Lignins from different sources differ disti - - - - . Color : The light absorbing properties 4 of nonphenolic hydroxyalkyl lignin derivative s have been improved by an oxidative treatment with chlorine dioxide ( 10 ) . It appears possi ble to remove up to 95 % of the color of kraft ligni n without significant yield loss. - 207 REFERENCES . CHRISTIAN , D.T. , LOOK , M. , NOBELL , A. and ARMSTRONG , V.S. U.S. Pat. 3 ,546 ,199 ( 1970) 2 . WU , L.C. F. and GLASSER , W.G. J. Appl. Polym. Sci. 29 , 1 1 1 1 ( 1984) . GLASSER , W.G • » BARNETT , C.A • r RIALS , T.G., and SARAF , V.P. J. Appl. Polym. Sci. 29 , 1 3 - 1815 ( 1984) 4 . SARAF , V.P. and GLASSER , W.G. J . Appl. Polym. Sci. 29 , 1831 ( 1984) 5. RIALS , T.G. and GLASSER , W.G. Holzforschung 38, 191 ( 1984) 6. RIALS , T.G. and GLASSER , W.G. Holzforschung 38 , 263 (1984) 7. SARAF , V.P • r GLASSER , W.G• t WILKES , G.L. and McGRATH , J.E. J. Appl. Polym. Sci., in press 8. SARAF, V.P • GLASSER , W.G. and WILKES , C.L. J. Appl. Polym. Sci• t in press 9. GLASSER , W.G • r BARNETT , C.A. and SANO , Y. Appl. Polym. Symp. 37 , 441 ( 1983) 1 0. DILLING , P. and SARJEANT , P.T. U.S. Patent 4 ,454 ,066 ( 1984) $ •. 208 - CHEMICAL PROPERTIES OH/ O7 HYDROXYL RADICALS IN OXYGEN BLEACHING H* » O * ' •OH pK0= 11.9 MONICA EK AND JOSEF GIERER DIVISION OF WOOD CHEMISTRY Electrophilic character •OH TORBJORN REITBERGER - ' O DEPARTMENT OF NUCLEAR CHEMISTRY Nucleophile Only * OH participates in rapid electron transfer reactions with inorganic anions, eg 1 ROYAL INSTITUTE OF TECHNOLOGY ' CO 3 2cr S 1O3 •OH * - S 100 44 STOCKHOLM, SWEDEN •OH •OH ABSTRACT dation is studied using appropriate model compounds . . Thus con- only one kind of radical operates in the system version of reducing solvated electrons into oxidizing hyd . molecular oxygen However , this initial step , which almost exclusively takes place in the lignin part , is energeti - roxyl radicals is crucial N O 2 oxide anion, 0 , is a fairly selective species , capable of . By further reduction the superoxide anion yields hydrogen peroxide , . This species is generally considered to be responsible cellulose during oxygen bleaching and thus causing viscosity losses I t should be noted , however , that the hydroxyl . radical is a very weak acid which becomes deprotonated above . As shown in Fig. 1. there are important differences anion. reduction of oxygen may explain the difficulties encountered reactive species are simultaneously present . We try to solve this problem by applying radiation chemical methods ( 1 ) . The absorption of Co y - rays or a beam of high energy electrons in water generates approximately equal numbers of powerful oxidizing ( * OH ) and reducing ( e ' * H ) radicals ^ aq * together with smaller yields of the molecular products H. 1 and H O ^^ OH " . This operation also expels dissolved oxygen In a N Osaturated solution , hydroxyl radicals constitute about 92 % of all radicals acting in the system. The remaining frac tion of radicals , i . e . hydrogen atoms, can generally be neglected. Thus , radiolysis of dilute aqueous solutions saturated with N O closely approximates a monoradical system suitable for OH- radical investigations . Knowledge of the absorbed dose immediately provides a Quantitative basis for determination of the products formed. Our radiation sources are a Co - facility and a pulsed electron accelerator A very short pulse of electrons can deliver enough energy to produce an observable concentra tion of radicals By temporal analysis using fast electronics , real time kinetics of the radicals formed may be followed . This pulse radiolysis technique has received wide applications in chemistry and biology and has contributed significantly to the understanding of radical - mediated reactions . The combined use of pulse - and y - radiolysis to elucidate problems associated with bleaching chemistry is a ^ # ^ . The complexity of the chemistry involved in the stepwise achieved in conventional bleaching studies , where several ‘ OH . in chemical properties between the hydroxyl radical and its in the chemical interpretation of oxygen bleaching processes - eaq ^ for the greater part of the chain ruptures taking place in . the hydroxyl radical , its behaviour must be studied i n the absence of interfering species . This can hardly be . This conversion is accomplished according to the reaction : . The first reduction product , the super - e .g - by saturating the solution with dinitrogen oxide ( N ? 0 ) , cally unfavourable and requires a high alkalinity to pro - In order to elucidate the role of a particular species , ^ 0 lozonidanion) Oj The ensuing chemistry is much simplified i f essentially on structural elements of the phenolic and enol ic types by pH 12 • . . which may undergo a metal ion catalyzed decomposition giving rise to the extremely reactive hydroxyl radical , ’OH - Figure 1 Oxygen bleaching is initiated by an electrophilic attack ^ ^ Only O * reacts with O 2 - 0 not only to lignin degradation but also to partial degra - acting as a mild oxidizing or reducing agent ' OH 3 . Compared to molecular oxygen these intermediates are less selective , contributing ceed efficiently " CO* CIt2 SiO Only « OH adds to n - electron systems^ e g I t was early recognized that radicals play an important dation of cellulose OH- - INTRODUCTION r 61 e in oxygen bleaching reactions * 2 The selectivity of hydroxyl radicals , generated by radiation, with respect to lignin and carbohydrate degra —> OH . new approach . RESULTS AND DISCUSSION We have started our investigations on reactions induced by radiolytically produced hydroxyl radicals with a few model compounds representing important carbohydrate and lignin structures , Fig . 2. . 209 . Table 1 . CH-OH a Absolute rate constants determined by pulse radiolysis CH O Compound - - CHOH KH 3 k ( dm mol ’ s’ ) . Veratrylglycerol -B- guaiacyl ether 2 . Veratrylglycol OCH3 XH3 1.7 3 . Me B - D- glucopyranoside 1010 3.2 109 2.6 109 . Overall selectivities determined by y - radiolysis Carbohydrate compound Selectivity* -- Me p- D- glucopyranoside 2.7 Veratrylglycerol - 3guaiacyl ether Me 0- D- xylopyranoside 2.2 Lignin compound Veratrylglycerol 0 guaiacyl ether . 10 1.5 4 . Me 3- D - xylopyranoside b Figure 2 10 1 kL / kc Research items we are working on are summarized as follows 1 . Study of the degradation of model compounds representing important carbohydrate and lignin structures by the ac radical reaction with carbohydrate and 1 iqnin models ref - lects the electrophilic nature of the hydroxyl radical , - . . 0H, generated by radia tion methods . Analysis of the products formed . tion of oxidative radicals , e g The pronounced difference in the rates of the hydroxyl * . Determination of the reaction rates of the above models and their dependencies on structural features . 3 . Competitive experiments using carbohydrate and lignin which adds to the aromatic nuclei of liqmns in preference of abstracting hydroqen from carbohydrates . The addition reaction is almost diffusion controlled and proceeds via a 2 short lived charge transfer complex . At pH< 3 this inter - mediary complex yields the radical cation of the lignin . Hydrogen ab- model compounds and isolated carbohydrates and lignins model which may decompose monomolecularil y to elucidate the limits of selectivity for the action of straction by hydroxyl radicals is a sterically more hinde red reaction than addition of hydroxyl radicals to the TT . various radical species Our studies on pure lignin model compounds have generated considerable insight into the mechanism of CQ- C cleavage ^ . These - - . electron cloud of aromatics This explains the intrinsic selectivity of the hydroxyl radical found in the system . As the hydroxyl radical anion is a nucleo- and demethoxylation effected by hydroxyl radicals investigated results which contribute to the understanding of microbial lignin degradation , will be reported elsewhere philic species i t does not add to aromatic structures fas ter than i t abstracts hydrogen from carbohydrates Thus at . Selectivity is a key word in bleaching but its quantita . pH> 12 the intrinsic selectivity is lost - tive meaning is not well defined In our opinion selectivity is a kinetic concept , which may be estimated from the rela .. - tive reaction rate of a particular oxidant , e g the ‘ OH , radical with specific carbohydrate and lignin model compounds Two complementary techniques were applied. Most straight forward i s a pulse radiolysis measurement which clearly avoids possible secondary reactions obscuring the initial radical attack . The absolute ’ OH radical reaction rates with parti - . The significant difference found between primary and overall selectlvities indicates secondary reactions which either restores the lignin model or enhances the conversion . of the carbohydrate model . Both possibilities can be formulated by reasonable assumptions . At the presert time we are not able to ascribe the secondary effect to a specific reaction . ry We have recently found that Mg cular model compounds were measured using a competition . ions have a remarkable tical density at the end of the pulse due to the transient retarding effect on the rate of hydrogen abstraction from Me B D- glucopyranoside by hydroxyl radicals Our analysis 4 shows that Mg " ions form surprisingly strong carbohydrate ’ OH adduct with thiocyanate at 500 nm complexes containing one or two ions per glucoside molecule method . This is based on the measurement of the initial op- - . - . The grimary ’OH radical selectivity for a particular pair of carbohydrate and lignin models is given by the ratio of depending on the Mg^ / carbohydrate concentration ratio the corresponding absolute rates small but . The other technique applied comprised steady state Y - radiolysis of mixtures of one carbohydrate and one lignin - model compound and HPLC analysis of the degree of conversion effected by ’ OH radical reactions By varying the concentra . - tion ratio of the models , i t is possible to calculate the overall selectivity of the * OH radical with a particular pair of carbohydrate anc iqnin models Table 1 , suntnarize' 210 . . oim of the results so far obtained. r > — At pH 7 the protective effect of Mg * * increases ions i . * ratner strongly with increasing pH up to pH~H At pH~10 the hydrogen abstraction rate i n the presence 24 of Mg ions is only about b% of that measured in the absence of Mg** * ions In our opinion the observed kinetic effect due to the formation of Mg 24 / carbohydrate comp lexes explains the increased selectivity obtained by addi tion of Mg 24 ions in oxygen and peroxide bleaching sequencer * . - REFERENCE . FAtfENl ALE , J H , ft BUSI , F . The study o * transient species by Publishing Company . - » processes anu electron pulse ra i i s . D Reidel Dordrecht ; Boston , London ( 1982 ) . RESULTS AND DISCUSSION ENZYMATIC DEGRADATION OF CELLULOSE CRYSTALS A typical preparation of Valonia microcrystals is shown in Figure 1 The crystals consist in segments of the initial cell wall microfibrils They have the same width ( ca 15- 20 nm ) and perfection than the original H . CHANZY and B. HENRISSAT microfibrils, but are of various lengths, ranging from 500 nm to several microns. In Figure 1 , it can also be seen that the tips of the microcrystals CENTRE DE RECHERCHES SUR LES MACROMOLfcCULES VfcGfcTALES, CNRS BP 68 38402 SAINT MARTIN D’HERES, FRANCE . have irregular shapes , ranging from very sharp oblique cuts to blunt extremities , sometimes carrying microfibril debri 9. In addition , several microcrystals ( see arrows in Figure 1 ) display defects which correspond to ABSTRACT areas attacked by acid , but not fully disrupted by the mechanical Valonia and bacterial cellulose microcrystals were digested with purified components of the cellulase complex from Celluclast* Four agitation. ; enzymes were considered , namely the exo CBHI and CBHII , together with the endo EGI and EGII . CBHI led to thinning and sub- fibrillation of the crystals whereas CBHII eroded only one of their two tips With EGI r . ' f ’ .v . r NJ ^ * . *» • , N -. < N «H •M . • SEE V ^ KEYWORDS Cellulase, Cellulose Microcrystals Figure 1 * * # w * * . Vi . . . ” .\ •r 1 . * \ . #> n" - t i i iff s h ir * „ J INTRODUCTION v ' i V 80® (Hu) . . . A v " .y • « » y. A {'' •r ' * r ii . * r- • • • 1 1 v* - *, - l l ? 4 ’ \ and EGII , the attack was localized at kinks and defects occurring along the microcrystals Mixture of the purified enzymes (such as CBHII + EGII ) gave composite attack together with a synergistic action . . . • • V .. < • sji r \ * s . Transmission electron micrograph of Valonia microcrystals after negative staining with uranyl acetate 1 he biodegradation of cellulosic material is a complex process which When the Valonia microcrystal 9 were digested by CBHI ( 1 ) , they involves the interaction of multi-components enzymes on partially crystalline solid substrates. To date , the mechanism of cellulase attack is became degraded by erosion and sub- fibrillation. This is illustrated in Figure 2 where one can see that the crystals have become narrower while only partially understood even though great efforts have been made in their initial length appear maintained purifying the various cellulase components and testing them individually longitudinal sub-fibrillation is clearly evident. In several instances, a . on various substrates. When doing so it is found that the accessibility and crystallinity of the substrates are two important features which will delay the enzymatic digestion . The authors, however , do not always agree on the relative influenced of these two parameters. The present work i 9 an attempt of simplification by examining how well characterized and dispersed - i.e highly accessible -cellulose crystals are digested away by the various cellulase components. EXPERIMENTAL Microcrystals of Valonia and bacterial cellulose were prepared by acido- mechanical treatment of Valonia cell wall or pre - purified bacterial cellulose pads A crude Celluclast* mixture, together with purified 1, 4 - 0- D glucan . . glucan hydrolase ( EC . 3 2.14 EG ) I and II and 1 , 4 p D glucan - cellobiohydrolase ( E C 3.2. 1 91 CBH ) I were kindly provided by M Schulein from Novo Industri CBHII was purified by successive . chromatography of Celluclast* on DEAE Sephadex followed by Phenyl Sepharose and Sephadex G 50 wjk Figure 2 Transmission electron micrograph of Valonia microcrystals after 36 hours of interaction with CBHI Specimen negatively stained with uranyl acetate A suspension of bacterial cellulose microcrystals attacked by CBHI was analysed by x - ray Electron microscopy was achieved with a Philips EM 400T after The results are displayed m Figure 3 and compared with those of the initial sample In the hydrolyzed sample , one notices a marked decrease of the intensities of the equatorial diffraction negative staining of the specimen lines ( 1 10 ) , ( 110) and ( 020 ) whereas the meridional ( 004 ) together with the ( 102 ) lines have maintained their initial intensities These x ray * The digested bacterial cellulose microcrystals were also studied by x ray diffraction analysis by using a Siemens generator Hat film Wahrus vacuum camera equipped with a experiments corroborate previous electron diffraction data obtained on hydrolyzed Valonia microcrystals ( l ) 211 Figure 5 Figure 3 Radial densitometer tracings of x - ray powder diagram obtained with A ) initial bacterial cellulose microcrystals . B ) same sample but after 16 hours of digestion with CBH1. . CONCLUSIONS The results presented here bring some clarification on the following The action of CBHII on Valonia microcrystals ( 2 ) difFers markedly from that of CBHI and corresponds to what one could expect for a classical exo- enzyme. In that case , each of the crystals became eroded at only of their two tips, whereas the other tips remain unaffected Transmission electron micrograph of Valonia microcrystals digested for 16 hours with a 60 40 mixture of CBHI 1 and EGII A ) low magnification B ) enlarged area of A . The specimen was negatively stained with uranyl acetate points one CBHI is able by itself to degrade fully highly crystalline cellulose This is substrates Its initial mode of attack appears to be of an "endo ” rather illustrated in Figure 4 Typically , the eroded tip displays an elongated pointed shape , with the point roughly centered along the long axis than an ’’exo'* type of the crystal . CBHII follows the classical ” exo" attack mode as it erodes the f i cellulose microcrystals at only one of their ends . This in particular confirms the parallelism of the cellulose chains in the Valonia > /“y cellulose microcrystals . / i- l* 04 - vV V> !< * • ; • EF * I > •{ when CBHII and EGII are mixed , the erosion occurs not only at one of ,y v ip . »4 *I « »,/rI^ •2m *. • « the crystals tips but also at the defects found along the crystals Such observations illustrate well the synergism between EGI and CBHII mm? ^ I? * ’ •* Since CBHI and CBHII have different modes of attack , their synergism can also be explained REFERENCES / ' «* i * i 4 1 ) "C L* rr A A 'll •» Figure 4 I Transmission electron micrograph of Valonia microcrystal after 16 hours of interaction with CBHII The specimen was negatively stained with uranyl acetate NR and R correspond to non reducing and reducing tips of the crystal When the microcrystals are digested with a mixture of CBHII and EGII , the erosion occurs not only at one of the tips of the microcrystals , but also at the kinks and defects which become also sites of unidirectional attack Such H phenomenon is illustrated in Figure 5 It corresponds to a sample treated as in Figure 4 , the only difference being that the enzymatic solution contained a 60 40 mixture of CBHII and EGII In that case , the digested sjiccimen appears ns a string of pointed tip fragments, each point being oriented toward the pointed tip of the partially digested crystal 212 . . . . . 1 CHANZY , H HENRISSAT, B VUONG R and SCHULEIN M FEBS Letters, 153. 113 ( 1983) 2 CHANZY. H and HENRISSAT. B , FEBS Letters, in press t l* s t i l l i n t h e m a t e r i a l s. STRUCTURAL CHANGES IN LIGNIN DURING STEAM HYDRO LYSIS OF Aspen wood - STRUCTURAL ANALYSIS 1 3C DANIELLE R. ROBERT and MICHEL BARDET NMR i n l i q u i d p h a s e : t h e s p e c t r a a r e r e c o r d e d a t 6 2 . 9 MHz o r 5 0 . 3 MHz f r o m s a m p l e s i n L a b o r a t o i r e s d e C h i m i e /D R F , C e n t r e d ' E t u d e s NucUaires de Grenoble , 85 X , 38041 Grenoble Cddex , France DMSO D6 - - T° 3 2 3 K. Quantitative analysis : the yield of extracted lignin translates the efficiency of the process, and allows correlations between the data and the . Keywords : lignins, steam hydrolysis 1 3 e x p e r i m e n t a l c o n d i t i o n s. T h e p e r t u r b i n g e f f e c t s C NMR , DEPT. on signal intensities are suppressed by using an g a t e d e c o u p l e d s e q u e n c e ( 3). inverse In order to find in biomass an inexpensive and large supply of chemicals and organic materials, H y d r o x y l g r o u p s (a c e t y l a t e d s a m p l e s) : t h e procedures involving steam hydrolysis of wood data are given in figure 1 for the first set of h a v e b e e n l a t e l y , r e c o n s i d e r e d e x t e n s i v e l y ( 1 ). experiments ; These techniques make readily available directly the correlation between the yield of extracted from wood chips, its three major components : lignin , and the number of free phenolic groups is c e l l u l o s e , H E M I C E 1 1 u l o s e a n d l i g n i n s. g i v e n i n f i g u r e 2a ). for the second set of experiments , In this study , we have been concerned by the structural analysis of lignins fractions, extrac r e s : t h e I o t e c h p r o c e s s ( 2 ). A n a t t e m p t t o c o r - ft <1 ted from Aspen wood , using one of these procedu relate the data obtained , with the experimental . 4« #4 1 ppm .* 4 J ppm Ac 2* • Ac HI 4 PPm :O H ia> A w n twt . - OH# Aram »M Ac AKW MWl c o n d i t i o n s o f t h e s t e a m h y d r o l y s i s h a s b e e n m a d e. Ac r » C •(Ml •OH# - OH V 21 • • •14 • la4 M » A A ¥Vt Ac p Ubwi • Miwc ( 17 IV Ac I m 44 t c 1 21 VI Ac I » 44 I 14 4 44 • V* Ac I I 14 4 4 * 4 42 t Ac I * We have been supplied with 1ignoce 1 l u losic materials, by the Pilat plants, build in Centre ll U 44 SAMPLES MWlac •« 1 44 - VHA T e c h n i q u e d u P a p i e r o f G r e n o b l e ( F r a n c e ). T h e s e s s m p ’e s c o m e f r o m t w o s e t o f e x p e r i m e n t s : F i g u r e 1. 1ST SET OF EXPERIENCES P * MO BARS CONSTANT 2ND SET OF EXPERIENCES P ( BARS ) AND T ( SEC ) VAR| ABLE Quantitative determination of the groups from the acetoxyl l 3C NMR s i g n a l s. - - - ge of the alkyl aryl ether bonds, which can be 1 2 1 2 3 40" 60" 90" 165" 4 5 6 7 6 45 35 45 25 35 25 7 20 8 50 35 3 4 5 9 205" 240" traced by the signal intensity of the aromatic - - c a r b o n s C 3/ C 5 , a n d c o r r e l a t e d t o t h e y i e l d o f 45" 45" e x t r a c t e d l i g n i n ( f i g u r e 2 b). T h e t w o c o r r e l a 10" 2 a r e c o h e r e n t. tions in figure 205" 125" 125" 125" -OH iot /C6 C 3 40 •4 To extract the lignin part , we used a basic fractionation s c h e m e ( l b ) , w h e r e t h e d r y liqno 15 . w i t h d i o x a n - w a t e r 9/ 1 , o r w i t h . ther , has been consi- Precipitation in •8 •8 •7 •6 - 10 8 • l * 1 09 01 02 03 0.4 - 05 06 0 O -4/C6 C 3 * l red as a way to purify the Lignins from extrac ^ tiv e s , a n d f r o m l o w m o l e c u l a r w e i g h t p h e n o l s , - Figures 4 a> *RJ • •2 •3 20 .. Extracted either 30 - •R •1 •7 c* l l u l o s i c m a t e r i a l s e x t r u d e d f r o m t h e b l o w e r tank , i s d r i e d , w a s h e d w i t h w a t e r , t o g e t r i d o f t- he h e m i c e 1 1 u 1 o s e s , a n d l o w D P phenols, then - % lignin yield •5 • -O H 6- 0 4 s y r i n g y l s t r u c t u r e s : t h e r e i s a c l e a v a T * VARIABLE (LENGTH OF HYDROLYSIS) CltoM * 4 03 •5 04 b, as 08 - a7 OH 25 BARS *3 45 SEC . REFERENCES a / M A R C H E S S A U L T , R . H. a n d S A I N T P I E R R E , J . "P r o c e e d i n g s o f C h e m r a w n C o n f e r e n c e " , T o r o n t o 1 9 7 8. P e r g a m o n P r e s s ( 1 9 0 0). b/ M A R C H E S S A U L T , R . H. , C O U L O M B E , S. , M O R I K A W A , H. a n d R O B E R T , D. C a n J . C h e m . 6 0 , 2 3 7 2 ( 1 9 8 2 ). c / H E M M I N G S O N , J. A . J . o f W o o d C h e m . T e c h . 3 , 2 8 9 ( 1 9 8 3 ). d / C H U M , J .C. , R A T C L I F F , M . , S C H R O E D E R , H. A . a n d S O P H E R , D. i b i d , 4 , 5 0 5 ( 1 9 8 4). 2. a / I o t e c h. C o r p., C a n . E n e r g y R e s. A l e s t r. 3 4 0 0 2 , 5 , 2 2 ( 1 9 8 0). b / D E L O N G , E. A. C a n. P a t 1 , 0 9 6, 3 7 4 (1981) IUJU LbiLLLi ^ L. . -< m 2 AA - fA. 1 PPm b > 50 BARS 125 SEC. Total b> spectrum w' /VL 3 . R O B E R T , D . R , a n d B R U N O W , G. 3 8 , 8 5 ( 1 9 0 4 ). 4. a / L A P I E R R E , C. , M O N T I E S , B. , G U I T T E T , E. a n d L A L L E M A N D , J . Y. H o 1 z f o r s c h u n q 3 8 , 3 3 3 ( 1 9 8 4). b / B A R D E T , M., F O R A Y , M . F. a n d R O B E R T , D. M a k r o m o l . C h e m . 1 8 6 ( 1 9 8 5 ). 1 6*2 <« C C P /M A S S P E C T R A I N S O L I D P H A S E T h e s p e c t r a r e c o r d e d a t v l sC * 5 0 . 3 M H z c o n firm the cleavage of the 6 0 4 linkages , and -- structural changes can be traced on these . epect r a MONOMERS AND DIMERS FRACTIONS T h i s s t u d y h a s b e e n c a r r i e d a l o n g w i t h D r. K. L I N D Q U I S T ( U n i v e r s i t y o f G d t e b o r g S w e d e n) f r a c t i o n s i s o l a t e d b y G P C ( 5) f r o m t h e J 4M no e x t r a c t i we observed a low yield in - and syringaresinols as the H o 1 z f o r s ch u n g - 1) tu hORU* r C , . . CM J DEPT - 1. a> j DEPTCM . 214 summa rized as follow : h y d r o l y s i s. might which can be - main - 5. B A R D E T , M . , R O B E R T , D. a n d L U N C Q U I S T , K. S v e n s k P a p p e r s t i d n. 6 , 6 1 ( 1 9 8 5 ). T R A N S I T I O N M E T A L ;0 \ C A T A L Y S I S O F T H E H Y D R O G E N PEROXIDE OXIDATION OF A LIGNIN MODEL COMPOUND PHILIP K . SMITH THOMAS J . MCDONOUGH WEYERHAEUSER CO. TACOMA , WASHINGTON INST. OF PAPER CHEMISTRY APPLETON , WISCONSIN ABSTRACT The kinetics of reactions occurring during delignification of softwood kraft pulp with H 0 2 (or oxygen) under alkaline conditions were studied in a model system . ^ Very l o w l e v e l s o f Fe and Mn s a l t s were found to catalyze H C decomposition to a greater extent than oxidation of a residual ^ ^ lignin- related compound . In contrast , catalytic l e v e l s of either ferricyanide or Cu s a l t s produced an overall increase in the degradation of the lignin model at lower levels of decomposition. INTRODUCTION The feasibility of using hydrogen peroxide as a delignifying agent in the first s tage of a bleach sequence for alkaline chem ical pulps has recently received considerabl e attention ( 1 ,2 ) . This process , like oxygen bleaching , offers pollution abatement as a major advantage , but has the addition al advantage of not requiring pressurized equipment . Studies ( 2 , 3 ) have shown that the removal of heavy metals from pulp ( by pretreatment with acid and/or chelating agents ) signifi cantly enhances the extent of peroxide d elignification. The negative effect of these metals is believed due to metal ion catalyzed decomposition of hydrogen peroxide . On the other hand , Agnemo and G e l l e r s tedt ( 4 ) have tion demonstrated that peroxide decomposi is necessary for phenolic structures of the type present in lignin to be at tacked by hydrogen peroxide . Peroxide de composition involves the intermediate formation of radical species such as 0 a n d HO * ( 5 - 7 ) . I t i s likely that oxygen and these oxy - radic als are tne species which attack phenoli c lignin units during peroxide delignificat ion ( 4 ) . Transition metal ions can be involved in this reaction in a second way . The rate determining step in the oxidation of ph enols with oxygen and peroxide in alkali is believed ^ to be phenoxy radical formation ( 8 ,9 ) . Many t r a n s i t i o n metal ion s p e c i e s are quite effective single -electron oxidants . Landucci ( 8 , 10 ) has demonstrated that the salts of heavy metals commonly found in pulp (Cu , Mn , Fe ) c a t a l y z e p h e n o x y r a d i c a l f o rmation under alkaline conditions and in the presence of oxygen. It is evident that transition metal ions should play a central role in the reactions of lignin with hydrogen peroxide ( and oxygen) in alkali . The present study was directed toward understanding the relationship between transition metal ion catalysis of hydrogen peroxide decomposition and oxidation of a 1 ignin- related compound . The compound shown below - 1 , 1 -raethylenebis ( 2 - hydroxy - 3 -methoxy - 5 ( 2-carboxyethyl )b enzene ) o r MBB - was s e l e c t e d a s a model r e p r e s e n t i n g condensed phenolic units in residual lignin . The e f f e c t s of c a t a l y t i c quantities of Cu, Mn and Fe s a l t s ( and compiexed Fe ) o n t h e kinetics of both hydrogen peroxide decomposi t i o n and MBB o x i d a t i o n w e r e s t u d i e d . E x p e r i mental details are given elsewhere ( 11 , 12 ) . CH 2 OCH 3 MBB R = - CH2- CH 2- COOH RESULTS DecomPos * t ion Kinetics The k i n e t i c s o f hydrogen peroxide decompos i t i o n i n t h e r e a c t i o n s y s t e m w i t h o u t MBB present were studied first . The r a t e e x p r e ssion for this reaction i s given by: )/dt - d( H (H ) 1 (1) Note that all rate constants evaluated in 202 - kl 202 t h i s s t u d y a r e f o r c o n s t a n t ( H0 ~ ) a n d t e m p e r a t u r e ( 4 5 °C ) . Although the pH o f t h e r e a c t i o n s o l u t i o n s ( w i t h o r w i t h o u t MBB p r e s e n t ) were observed to increase slightly as the peroxide decomposed t o oxygen , t h e i r pH remained in the interval 11.0- 11.4 and the ( HO ) w a s c o n s i d e r e d c o n s t a n t . Data collected from decomposition runs o v e r t h e i n i t i a l ( H O , ) r a n g e o f 1 5 - 8 4 0 mM ( without any additives ) were analyzed b y the initial rate and differential methods. Rates were determined graphically from the (lUO J - timc plots . Results of this analysis ^ indicate that the reaction order ( n. ) changes L * ^ 215 from 2.5 to 2.0 as the (H 702) is decrease d below about 60 mM ( rate constants are listed in Table I ). The level of decompos ition observed in this experime nt is attribut ed to a "backgrou nd" level of catalyst s present in the reaction system in trace levels. Table I. H202 Decompos ition Kinetics in the Absence of MBB. Metals added as the salts: MnS04 > CuS , 04 - - FeS04 Conditio ns: pH 11.0 11.4 , 45°C, (H2O ) range 90 150 mM. - 2 Metal Ion Add 11 ive Additive Level , Reaction Order , uM nl 2| 2. 2.5 Rate Constant , k1 1.36 0.51 1.69 7 0.34 5.80 Fe Fe 18.2 285 1.0 1.0 Cu Cu Cu Cu 1.8 9.1 18.2 285 1.0 1.0 1.0 Mn Mn Mn 9.1 18.2 285 Peroxide Decompos ition Kinetics in the Presence of MBB. Metals added as their salts: FeSO , K 3 Fe(CN)6 (FC), MnS04 , CuS04. Reaction conditio ns: (MBB)o = 20 mM , (H )o = 100 mM , pH 11.0 11.4 , 4 5°C. ^ 202 - Addit 1 ve Cone. , React ion UM React ion Order , n2 Control Ratea 2.0 Constant , k2 5.42 0.20 Fe 300 1 .5 11.6 1.1 FC 300 1.5 7.28 0.57 Mn 21 1.0 19.5 0.6 Cu 12 1.0 10.8 0.3 3 ob None None Table II . 3.50 0.09 0.33 8.45 + 0.07 8.72 0.26 8.83 0.49 26.4 3.1 1.0 1.0 4.85 7.33 202 1.0 1.0 r% ' min " 1 * Units (order): mM 10 5 ( 2.0 ) , • 10 4 (1.5), min - 1 . mM 0.5 . min 10 ‘ 3 ( 1 . 0 ). 951 confiden ce limits. ' - * ’ ‘ 0.06 0.14 58 Units ( order): min - 1 . 10 ’ 3 ( 1 . 0 ), mM - 1 * IQ 5 (2.0), mM 1.5 . min 1 * 10 6 (2.5) . % confiden - * * ’ ce limits. 95 ^ (H202) less than ca. 60 mM. The effects of added transiti on metal ions on the decompos ition kinetics were also investig ated. In agreement with previous studies (4 ,5) first order kinetics were observed in these experime nts (Table I ). The data showed an excellen t fit (correlat ion coeffici ent , r > 0.99) to the integrat ed form of equation (1 ) with n 1.0. Hydrogen peroxide decompos ition during each MBB oxydatio n run (Table II) was monitore d ( independ ently of its consumpt ion by MBB) by measurin g the volume of oxygen evolved. The rate law for decompos ition under these conditio ns was assumed to be : n? d( Ox)/ dt • k (H ) ( 2) 2 The term ( Ox ) represen ts the concentr ation of decompos ed H O as measured by oxygen evolutio n (2 H -, 02 02 2H 70). The effects that the additive s had on the decompos ition and total consumpti on of H O , in the MBB oxidatio n runs are shown in Figures 1 and 2 , respectiv ely. ^ - 202 ^^ * . 216 REACTION TIME . min. Figure 1. Effects of added metal ions on H,07 decompos ition during the MftB ^ react 1 0 ns (conditio ns given in Table II). The data in Figure 1 were analyzed by the differen tial method , with the rates , d(Ox )/ dt , determin ed graphica lly. This analysis showed that the reaction order ( n 7 ) for the Control , Cu and Mn reactions were essentia lly the same as the orders (nj ) found in the absence of MBB (2 , I and 1 , respecti vely ). The presence of MBB in the Fe reaction caused the reaction order to increase from 1.0 ( n ) to 1.5 ( n ). 2 A 1.5 order ( n 7 ) was also found in the reaction catalyze d by ferricya nide ions lFC ). ^ 20 100 18 51 E 16 CD CD 5 14 Control 12 0 40 80 120 160 200 . REACTION TIME m i n . Figure 2 : 0 Effects of added metal ions on t h e r e s i d u a l l e v e l o f H 2 0? d u r i n g t h e MBB o x i d a t i o n r e a c t i o n s ( T a b l e I I ) . = n 12 dt (3) The integral was approximated by applying Simpson ’ s Rule to the ( H 207 ) - t i m e d a t a o f Figure 2 . Plots of equation ( 3 ) for the o x i d a t i o n runs ( C o n t r o l , FC , Fe , Cu and Mn w i t h n * 2 . 0 , 1 . 5 , 1 . 5 , 1 . 0 a n d 1 . 0 , 2 respectively ) showed excellent linearity , r>0.99 . MBB O x i d a t i o n K i n e t i c s The MBB c o n c e n t r a t i o n - t i m e c u r v e s i n Figure 3 represent the net effect of the metal ion additives on the two overall reactions: h y d r o g e n p e r o x i d e d e c o m p o s i t i o n a n d MBB ox idation . In order to compare the catalytic e f f e c t s o f t h e m e t a l s o n t h e MBB o x i d a t i o n rate , the same general kinetic model was applied to the data from each reaction . The model , defined by equations ( 4 ) and ( 5 ) , represents a useful but simplifi ed description of the complex reaction systems under study . A first order dependence on ( MBB ) w a s assumed o n t h e b asis of a similar kinetic study by Agnemo and Gellerstedt ( 4 ) . As a f i r s t assumption , the order with respect to ( H 202 ) , , w a s s e t e q u a l t o The f i r s t term of equation ( 5 ) represents peroxide decomposition ; the values k and 7 n from Table II were used , The second 2 term represents H , 02 c o n s u m p t i o n b y M B B ( and i t s products ) . one . 120 160 200 Figure 3 . K i n e t i c p l o t o f MBB d e g r a d a t i o n b y H 202 w i t h a n d w i t h o u t m e t a l ions aaded ( Table II ) . The curves result from the computer model described in the text . nT - d ( MBB ) /d t » k ( MBB ) ( H (4) 5 202 ) — •* gives: (H O ) 2 2 80 REACTION TIME, min The rate constant , k , for each oxidation 2 run was evaluated using the integral method (Table II ) . Integration of equation ( 2 ) ( Ox ) 40 - d ( H 202 ) / d t = k ( H 2 202 ) n2 *k 4 ( MBB ) CHz 02 ) n3 (5) A computer program for parameter estimation from multiresponse data ( 13 ) was employed to obtain optimal values for the rate constants , k and kj ( 12 ) . The experimental data from t h e C o n t r o l , Fe , FC and Mn r e a c t i o n s showed a good f i t to the resulting calculated ( H O ) ^ t i m e a n d ( MBB ) - t i m e c u r v e s u s i n g t h e a b o v e model . Table III summarizes the rate constants f o u n d b y t h i s a n a l y s i s f o r t h e f i v e MBB oxidation reactions . For the Cu reaction the model accurately described the experimental data only when a zero order dependence on ( H 0 ) was assumed ( n * 0 ) . Application 2 of the differential and integral methods c o n f i r m e d t h a t t h e MBB o x i d a t i o n r a t e was independent of ( H ) for this reaction . ^ ^ ^ 202 DISCUSSION H 7Q 7 Decomposition The results presented above illustrate some of the complexities associated with the chemistry of hydrogen peroxide decomposi tion . The bulk of the literature concerning peroxide decomposition indicates that this reaction proceeds via a radical chain mechanism catalyzed by transition metal ion species ( 5 , 14 ) . Figure 4 depicts a set of reactions which wc believe are important in describing hydrogen peroxide decomposition in alkali ( 12 ) . 217 Table III. Rate Constants Evaluated by the Hydrogen peroxide decomposition was a c c e l e r a t e d by MBB i n t h e C o n t r o l , Mn a n d A similar Cu reactions ( cf . Tables I and I I ) acceleration was also observed in a study in which glucose was added to alkaline H^O ^ (16). This is probably due to the organic substrate acting as a chain transfer agent in the radical decomposition reaction. For example, the single electron oxidation o f MBB by M* p r o v i d e s a n a d d i t i o n a l r o u t e for M to be formed which, as shown in Figure 4 , i s involved in the chain mechanism for peroxide decomposition ( step 1). K i n e t i c Model A n a l y s i s. React ion C o n s t amni tns . k 3x l O b k 4 x l O Control 2.69 Fe a . S t .3 k 4 /k3 Relativeb 2.06 7.7 1.00 3.60 2.30 6.4 1.34 FC 5.39 3.78 7.0 2.00 Mn 8.60 7.23 8.4 3.20 ( mM 1 " ’ # k3 Constants ( mjin M k 3x l 0 k xlO2 ' Cu ^ 5.90 4.95 Stoichiometry 8.4 MBB O x i d a t i o n At the levels added the metal ions can be listed in order of decreasing catalytic . a c t i v i t y w i t h r e s p e c t t o MBB o x i d a t i o n Ratio of k 3 for the given reaction to k3 for the Control reaction. f o l l o w s: C u > Mn > FC > F e ( >C o n t r o l ) Landucci ( 8 ) found the same ranking for these additives with respect to their a b i l i t y t o c a t a l y z e p h e n o x y r a d i c a l f o r m a t i o n. This provides strong evidence for the content i o n t h a t t h e i m p o r t a n t , r a t e -1i m i t i n g s t e p in the degradation of phenolic lignin units in alkaline hydrogen peroxide is phenoxy radical generation. On t h e b a s i s of t h e r e s u l t s of t h i s study and others ( 4 ,8,9) the reaction scheme depicted in Figure 5 may be considered t o represent the mechanism of destruction of phenolic lignin units by alkaline hydrogen p e r o x i d e. T h e s i n g l e e l e c t r o n o x i d a t i o n of the phenolate anion ( step 2 , Figure 5) The observed changes in the reaction order , n , with changes in the H 202 or metal ion concentration i s consistent with a complex reaction proceeding by two or more parallel paths ( 15). Other researchers have reported changes in this reaction order with changes in pH o r metal ion c o n c e n t r a t i o n ( 5 ) In the presence of Fe s a l t s the addition of MBB a l s o c a u s e d a c h a n g e i n t h e o r d e r ( n 1 1.5) = 1.0 , n 2 ^ . . H 202 4 M HO* 4 HO H 202 4 HO * 4 M4 (D H 02" 4 H 20 (2) HO / 4 M 4 HOJ 4 M (3) HOJ 4 HO - 0 / 4 H 20 (4 ) " - P) H|0 , M / M* MO; MO , O' MfO O # 4 M4 02 4 M 0/ 4 HO * 02 4 HO 2 0/ 4 H 20 02 - - R R 4 MO R (7) o* H 20 O/ (8 ) HO * 4 M HO 4 M4 (9) HO * 4 HO * H 202 . M (6 ) HO * 4 HO / Figure 4 HO (5) 4 HO/ 4 HO * , • ». •* 02 as o o o (10 ) - Proposed metal catalyzed radical chain mechanism for decomposition of H in aqueous alkali . 202 Figure 5 . Proposed oxidation scheme for substituted phenols under alkaline o x y g e n a n d / o r H -, 0 c o n d i t i o n s ^ . 218 ® r e s u l t s i n t h e f o r m a t i o n o f a r e s o n a n c e- ratio of the rates of decomposition t o MBB o x i d a t i o n. T h e Cu r e a c t i o n g a v e a non linear response due to the independence o f M B B o x i d a t i o n r a t e o n ( H -j O ) * stabilized phenoxy radical , Reaction with superoxide an : 'or oxygen ( s t e p 3, Figure 5 ) gives a cyclonexadienone hydroperoxide which is degraded to lower molecular weight products by ionic mechanisms involving attack by hydroxyl and hydroxperoxy anions ( 12 ,17 ). The mechanism of Figure 5 i s equally applicable to oxygen bleaching since a l l of the same s p e c i e s a r e p r e s e n t t h e r e. The observed independence of oxidation rate on (l C ) for the Cu reaction can be explained in terms of this mechanism, I t i s postulated that the Cu c a t a l y s t effectively competes with the phenoxy radical for superoxide ions. Thus reaction of phenoxy radicals ( which are generated a t high rates by the Cu catalyst ) with oxygen in step 3 ( Figure 5) becomes the favored pathway to the formation of cyclohexadienone hydroperoxide intermediate s. Since the decomposing hydrogen peroxide maintains a saturated solution of oxygen ( i . e. , c o n s t a n t c o n c e n t r a t i o n ) , t h e reaction r a t e d e p e n d s o n l y o n t h e MBB c o n c e n t r a t i o n . . - ^ Figure 6 graphically demonstrates that the added transition metal ions catalyzed H ,0 d e c o m p o s i t i o n a n d t h e o x i d a t i o n o f 2 2 t h e l i g n i n model t o d i f f e r e n t e x t e n t s. In the context of peroxide delignification of pulp, these results suggest that the - p r e s e n c e of some m e t a l s ( e . g . , Fe and Mn ) w a s t e H 2O t h r o u g h i n c r e a s e d d e c o m p o s i t i o n 2 t o oxygen. However , results of the Cu and FC r e a c t i o n s i n d i c a t e t h a t n o t a i l metal species may be considered detrimental . For instance, i t might be possible to increase the extent and rate of delignification for a given H O charge by controlling the levels 2 2 ^^ a n d t y p e s o f m e t a l i o n s s p e c i e s i n t h e p u l p. As a further extension, i t may be feasible to increase selectivity by means of catalysts which preferentially direct peroxide attack to the lignin fraction, thus minimizing damage to the carbohydrates . A large number of metal ions and their complexes are known t o catalyze superoxid e dismutation: H 20 2O2 - HO " 02 HO 2 For example, hydrated Cu( II ) ions have been shown to catalyze this reaction a t l f) diffusion controlled rates (k ^ I0 M 1 '1 (18) ) s However not a l l metal species are this active. Superoxide dismutation in the presence of ferricyanide/ferrocyanide ions occurs a t much slower rates ( k s 10 M 1 s‘ l ( 1 9 ) ) This l i k e l y explains why t h e d e p e n d e n c e o f MBB o x i d a t i o n r a t e on (H ) was the same in both the Control and FC r e a c t i o n s. - . ^ . * 207 C O N C L U S I 0 S.S A N D_P R A C T I C A L S I G N I F I C A N C E The results of this study are consistent with our present understanding of th e complex mechanisms of I O decompos i t ion ( Figure 4 ) and phenol degradation by (or oxygen ) under alkaline conditions ( Figure 5 ) The kinetics of these two reactions were shown to be strongly influenced by diffe rent transi tion metal ions added at catalytic l e v e l s. The relationship between the catalysis H 2 l) 2 ecompos i t ion and phenol oxidation by the metal ion species is illustrated in Figure 6. In this figure, the l evel of peroxide decomposed i s plotted as a function of t h e amount o f MBB r e a c t e d The slope of the lines in the plot repr esents the ^^ . ^ . 51 E 50 Q Ui O CL 2 o 40 O ID Q O« 30 N X u. o z 20 REACTION 10 Control Cu Fe FC O < a t Ui Mn U o o o 6 CONCENTRATION OF REACTED MBB. mM Figure 6 . Influence of metal ions on the r e l a t i o n s h i p b e t w e e n H ?0 ? d e c o m p o s i t i o n a n d MBB ox i d a t i o n t c o n d i t i o n s in Table II ) . ACKNOWLEDGEMENTS . We t h a n k D r s Norman Thompson a n d Werner Lonsky for many helpful discussions . The financial support of the member the Institute of Paper Chemistry is gratefully acknowledged , Portions of t h i s work w e r e u s e d by P. K . S m i t h a s p a r t i a l fulfillment of the requirements for the P h. D. d e g r e e a t T h e I n s t i t u t e o f P a p e r C h e m i s t r y . companies of 219 REFERENCES 1. LACHENAL , D. , C. de CHOUDENS , L. SORIA and P. MONZIE. 1982 TAPPI Int ' l Pulp Bleaching Conf Proceedings 145 51. - 2. ALLISON , R. W. (1983). - Paperi Puu 65( 2):71 7 3. GELLERSTEDT, G. and I. PETTERSON. J Wood Chem 5 Technol 2(3):231 - 50 (1952). 4. AGNEMO , R. and G. GELLERSTEDT. Chem Scand B33:337 42 (1979). Acta - 5. GALBACS , Z. M. and L. J. CSANVI. J Chem Soc Dalton Trans 1983:2353 7. - 6. ROBERTS, J. L. , M. M. MORRISON and D. T. SAWYER. J Am Chem Soc 100(1):329 30 ( 1978). - 7. KITAJIMA , N., S. FUKUZUMI and Y. ONO. J PhvsChem 82(13):1505 9 (1978). - 8. LANDUCCI , L. L. 4: 25 9 (1978). - Trans Tech Sect CPPA 9. KRATZL , K . , P. CLAUS , W. LONSKY and J. S. GRATZL. Wood Sci 6 Technol 8:35 49 (1974). - 10. LANDUCCI , L. L. - Tappi 62(4):71 4 (1979). 11. SMITH, P. K. and T. J. McDONOUGH . Paperst id , to be published. Svensk 12. SMITH, P. K. Transition metal ion catalyzed oxidation of a residual lignin related compound by alkaline hydrogen peroxide. Doctoral Diss. Appleton , Wisconsin , Institute of Paper Chemistry , 1984. - 13. ZIEGEL , E. R. and J. W. GORMAN. metrics 22:139 51 (1980). Techno 14. WALLING , C. (1975). - - - Accts Chem Res 8:125 31 15. HILL , C. G. An Introduction to Chemical Engineering Kinetics and Reactor Design P 86 i New York-: John Wiley j Sons , Inc. , 1977. - 16. ISBELL , H. S. and H. L. FRUSH. Res 59:C25 31 (1977). - Carb 17. GIERER , J. and F. IMSGARD. Acta Chem Scand B3 l :537 - 4 S , 546 60 (197TT 18. RABANI , J., D. KLUG - ROTH and J. LI LIE. J Phy Chem 77(9):1169 - 75 (1973). 19. ZEHAVI , D. and J. RABANI. 76( 25):3703 - 9 ( 1 972). 220 J Phy Chem REACTION OF ASPEN AT. SOUTHERN PINE WOOD FLAKES WITH GAS ;US KETENE > Roger M. Rowell Forest Products Laboratory , USDA P. 0. Box 5130 Madison , Wisconsin 53705 Richard H. S. Wang and John A. Hyatt Research Laboratories , Eastman Chemicals Division , Eastman Kodak Company , Kingsport , Tennessee 37667. ARSTRACT Acetylation of wood flakes prior to fiakeboard manufacture has been shown to greatly improve the dimensional stability of the finished boards. Previous work has centered on the use of acetic anhydride under various conditions as the acetylating agent. The need to remove the acetic acid co product of acetylation by acetic anhydride prompted us to examine the reaction of ketene with wood flakes since ketene is known to acetylate hydroxyl groups without forming by products. The use of - - ketene to acetylate wood was examined briefly by Tarkow in 1948 and by Karlson et al. in 1972. Ketene reacted both with southern pine and with aspen flakes at atmospheric pressure in the absence of solvent - or catalysts at 50 60°C to give maximum weight gains of about 172 and 202 , respectively. Aspen reacted more rapidly than did southern pine , but both reactions were - quite slow at least 10 hr reaction time was needed to reach maximum weight gains. Some darkening of the flakes was noticed ; reactions run at higher temperatures gave much more discoloration. acetyl analysis Infrared spectroscopy , solid state ^ carbon NMR spectroscopy , and established that ketene did effect acetylation of both species , but weight gains shove 122 did not correlate with acetyl content . Thus : aspen which was reacted to a 202 weight gain showed only 12.42 acetyl content on analysis. The non acetyl weight gain did not take the form of extractable material , and we V suspect that part of the ketene is being converted to * - chemically bound homopolymers in the flakes. * * . » - Flakeboards made from the ketene modified flakes showed a greatly reduced rate and extent of swelling because of sorption of liquid water or water vapor when the results were compared to those of the control boards. The improvement in dimensional stability was greater for aspen than for southern pine. Thus boards made from aspen flakes modified at the 122 weight gain level gave only 102 - swelling in thickness after 4 hr exposure to liquid water , whereas a corresponding experiment with southern pine gave 292 swelling. Control boards made from unmodified flakes of aspen and southern pine exnibited 612 and 402 swelling , respectively , under these conditions. Ketene modification was, in general , about as effective as acetylation with anhydride in improving the dimensional stability of aspea flakeboards , but ketene modification was much less efficient for southern pine. 221 - - various lignins produced in biomass to ethanol conversion processes based on steam explosion and COMPARISON BETWEEN LIGNINS PRODUCED EXPLOSION AND ORGANOSOLV PRETREATMENTS BY STEAM HELENA L. CHUM* , D. K. JOHNSON* , M. RATCLIFF* , S. BLACK*. HERBERT A. SCHROEDER** , AND K. WALLACE**. . 1617 COLE *SOLAR ENERGY RESEARCH INSTITUTE BLVD , GOLDEN , CO 80401 COLORADO STATE **FOREST AND WOOD SCIENCES UNIVERSITY FORT COLLINS , CO 80523 . . ABSTRACT A comparison between lignins isolated in wood pretreatments of steam explosion and organic aqueous solvent delignification (organosolv) with lignin isolated by mild wood ball milling is pre Wet sented for aspen (Populus tremuloides). analysis , quantitative carbon 13 nuclear magnetic resonance (NMR), molecular weight distribution by size exclusion chromatography , and ultraviolet absorption spectroscopic data are presented. The comparative ability of steam exploded and organosolv lignins with that of conventional kraft materials to replace phenol in phenol formaldehyde thermosetting resins is examined. - - - KEYWORDS: Lignin , Steam Explosion , Organosolv , Pretreatments , Thermosetting Resins , Aspen INTRODUCTION A number of methods have been suggested to pretreat wood (primarily hardwoods) so the biopolymers can be easily fractionated and the cellulosic fraction can become accessible to enzymes for hydrolysis to glucose and fermenta tion to ethanol. Examples of these methods are steam explosion , autohydrolysis , wet oxidation , and rapid steam hydrolysis/ continuous extraction (PASH), reviewed recently by Schultz et al. (1 ), as well as hydrothermolysis (2), and organosolv (3). The first five processes listed employ ateam and heat ; the sixth type of process employs an aqueous /organic solvent and heat , A compara five economic evaluation of steam explosion , rganosolv with methanol or ethano 1 water , and °Vet oxidation indicated that the pretreatment c sts were comparable. High value applications ° the lignins could largely decrease or offset Wood pretreatment and lignin isolation costs All three of these pretreatments produce CeUulosic substrates that can be hydrolyzed by enzyTT)es Potential markets for lignin utillza n have been reviewed (5). This paper compares ° - - - # ^ - - organosolv pretreatments. EXPERIMENTAL SECTION AND RESULTS Lignin sample preparation Steam explosion. The aspen exploded wood was supplied by lotech Corp. (55 s at 240°C). The procedure of isolation of the lignin through eth anol extraction has been described (6). Alter natively , after removal of the heraicellulosic fraction by water extraction , the lignin mate rials were isolated by extraction with 0.2 M KOH or methanol soxhlet extraction. . These samples are abbreviated as EESEAL , AESEAL , and MSESEAL respectively for ethanol , alkaline , and methanol preparations of steam exploded aspen lignins. Organosolv lignins. Aspen wood chips were pulped using methanol/ water (70:30 % v/ v) in a 1 iquor to wood ratio of 4: 1 in the presence of NaHSG (0.04 M and 0.1 M), H 2S04 (0.05 M), or H 3PO4 (0.05 M). The time at temperature of 165°C was 2.5 hours and rate of heating to temperature from ambient was 2.7°C/ min. After time at temperature , the digestor was cooled overnight and the liquor collected. This procedure allowed some lignin to reprecipitate onto the cellulose fibers. The organic solvent was removed by evaporation under reduced pressure , Redissolu tion of the HEMICELLULOSIC fraction and low molecular weight , water soluble lignins left a lignin fraction , which was filtered off. About 15% of the dry weight of wood was isolated in this way. The aspen wood used contained 17.1 % lignin (Klason and soluble) based on extractives free wood. The yield of the dry fibrous mate rials relative to the amount of dry wood charge varied between 49% 59% (H2SO4) and (0.04 M NaHS04). The permanganate number of these pulps ranged from 19 (0.1 M NaHS04) to 35 (H 2S04) Ball Milled Aspen Lignin. The procedure of Lundquist et al. (7) was used. The yield of pur ified milled wood lignin obtained was 13.4 g from 136 g of ethanol / benzene extracted aspen wood. Kraft lignins. A 1 iquor to wood ratio of 4.5: 1 was used with 14% active alkali and 20% sulfid 11 y. Pulping was carried out at 165°C for one hour Lignin isolation was carried out after concentration of the liquor to about 40% solids and precipitation with carbon dioxide (50 psi 80PC , 3 4 h). Lignin was purified by dissolution in base and reprectpitat ion by addition of acid . Other kraft lignins. Indulin AT , Reax 27 , and Keax 31 were supplied by Westvaco Chemicals Division , - - - - ^ - - - - - . - - - - . - . 223 Analytical methods The analytical methods used to characterize the lignins investigated in this work have been described by some of us (6). Quantitative carbon 13 nuclear magnetic resonance , employing the pulse sequence described by Robert and Gagnaire ( 3 ) was employed. In addition , independent methods were employed to confirm the NMR data. Acetylated lignin samples were used both in the NMR and in the high performance size exclusion chromatography. Quantitative acetylation of lignins. Lignin (0.2 1.0 g) is dissolved in 40 ml of a mixture of pyridine and acetic anhydride (1 : 1 ) under nitro gen atmosphere , heated to 55° C , and stirred for 48 60 h. After the reaction is completed , toluene (500 nil) is used to azeotropically remove both the pyridine and the acetic anhydride in a rotary evaporator (40°C). Small amounts of acetone are added to solubilize the acetylated lignins while toluene is being removed. Then , ethanol:acetone (1:1 , 50 ml) is used to azeotropically remove toluene left in the sample. The lignin sample is vacuum dried to constant weight. This procedure was checked with monomer and dimer lignin model compounds. For instance , for acetovaniHone this procedure gave 100.5% of the expected acetylated material , whereas conventional methods (precipi tation and extraction) gave only 84% of the expected amount. A blank of the acetylation reaction (for 1 g of lignin) gave about 10 rag of a material , indicating the possible presence of 1 % by weight of impurities , which are not detected by carbon 13 NMR , and which are low molecular weight materials by size exclusion chromatography (295 and 209 amu). High performance size exclusion chromat og raphy. I he acetylated lignins were subjected to size exclusion chromatography using four u spherogel columns (10 ,000; 500; and two 100 A ) from Altex. The solvent was tetrahydrofuran (Burdick and Jackson) at 1.0 ml / min. A Hewlett Packard 1090 (or 1084) high performance liquid chromatograph was employed with a HP 1040 diode array UV absorption spectrometer detector , Calibrations were performed with polysty rene standards ( Beckman / Altex), Igepal polymers (Aldiich), and lignin model compounds. Adhesive testing. The ability of the various lignins to replace phenol in phenol formal dehyde thermosetting resins was tested . The type of resin used in the adhesive testing was Cascophen 31 3 H , a high temperature setting phenol formalde hyde adhesive , manufactured by Borden Chemical Co. Levels of 30% 50% by weight of replace ment oi phenol with lignin were tested using the - . - - - ^ - - - - - - - - - 224 - British Standard 1204: Fart 1 : 1964 , and testi ng between 20 30 specimens per evaluation. - DISCUSSION Our sample of milled aspen lignin analyzed as C9H8.5 3.4(OCH3> 1.46 * which compares very well with literature prepared 3 3 ,o 0CH3 1.45 ° # ^ ^ by milling for 128 h vs. 720 h ^ our case. The NMR proportions of phenolic , primary , and secon dary hydroxy to aromatic carbons are 0.18 , 0.63 , and 0.62 respectively , which compare well with Robert et al. (10) of 0.22 , 0.77 , and 0.61 . The integration of carbons 3 and 5 (152.3 ppm) assigned to syringyl groups containing p 0 4 ether units is 0.47 compared to 0.6 (10). Steam exploded and organosolv lignins are formed in acid hydrolytic processes , As a result , the a O 4 and to some extent the p 0 4 alkyl aryl ether bonds that are predominant in the lignin polymer as well as the lignin carbohydrate bonds are hydrolyzed , thus leading to an increase of free phenolic units. AESEAL and MSESEAL have 0.25 and 0.22 p 0 4 ether content respectively in syringyl units and 0.6 in phenolic nydroxy / aromatic units. The organosolv lignins investigated here are obtained under progressively more drastic acid conditions (0.04 M NaHS0A , H P04 , 0.1 M NaHS04 , H SU ). On 3 going from 0.04 M to 0.1 M NaHSO the p 0 4 ether content in syringyl units decreases from 0.32 to 0.21 while the free phenolic content increases from 0.46 to 0.65/ aromatic unit , These NMK results agree within the experimental error with phenolic Oh determinations by conductimetric method. Detailed analytical data will be published elsewhere (11 ) The molecular weight distributions of the various acetylated lignin preparations are a distinct function of the delignitication proce dure as well as the extraction procedure. Acetylated AESEAL has the highest apparent weight (H * 2100), number , and z average molec ^ of the steam exploded lignin mate ular weights rials investigated. Acetylated EESEAL ( = 1050) molecular weight distribution is intermediate between alkaline and methanol (R e920) The ^ solvent extracted materials have smaller polydispersity than AESEAL (1.6 2.7 and respectively). The nature ot the isolated organosolv lignins is a marked function of the nature and concentration of the acid catalyst employed. There is a decrease in apparent number , weight , and z average molecular weight as Che pH of the pulping liquor decreases. Polydispersities also decrease pH the as decreases (Figure 1 ) in - -- -- -- - -- ^- -^ ^ - - - - - - Mw . - - - . - in the 21 U 400 nm range of the various acetyiated lignins at >600 apparent molecular weight show one absorption peak at about 275 nm , a shoulder with an absorption peak at about 240 nm , and a much more intense peak toward the UV , as expected for the three n+ ii* transitions. The absorption spectra molecular lower the of weight lignins (paucidisperse components present in all samples except ball milled) display more pronounced peaks toward the visible. For instance , in the H2SO4 sampLe distinct peaks are at about 220 , 240 , 275 , and 320 nm. The peaks at > 300 nm can be corre lated with structures containing carbonyl or un saturated carbon carbon bonds conjugated to the aromatic ring , Both vinyl side chains and car bonyl groups have been detected at levels of 0.1 0.2/ Cy each in the steam explosion and organosolv samples. The spectral data indicate a heavy con centration of conjugated carbonyl or unsaturated structures in the low molecular weight materials. Thus the need for analytical methods that do not fractionate the lignin materials. The ability of the various lignins described here to replace phenol in phenol formaldehyde thermosetting resins was tested (Table 1 ). The set time was such that all lignin samples would have time to cure at temperature. There were no significant differences between the lignins tested and the controls at 30% replacement by both shear strength measurements and wood failure. At 50% replacement , differences emerge , and Keax 27 , pine kraft , sweet gum kraft , Keax 31 , Indulin AT , and organosolv aspen (0.04 M NaHSO ) were found to be adequate replacement materials in order of decreasing suitability. Acknowledgements: Profitable discussions with Profs. K. Sarkanen and W . G. Glaaser are gratefully acknowledged. we thank Ur. Danielle Robert for obtaining some of the NMR spectra dis cussed in this paper. Borden Adhesives provided materials for the testing performed and repeated some of the tests. We thank Mr. J. Schmitz (Borden) for his assistance in the adhesive testing. This work was sponsored by the Biomass Energy Technology Uivision / UOE under FTP No. 51 b. The absorption spectra 2. - - - - - - - ^ - REFERENCES 1. SCHULTZ , T.P • * MCGINNIS , G. U., 6 BIEKNANN C J . Similarities and differences in pre treating woody biomass by steam explosion , wet oxidation , autohydroiysis , and rapid steam hydrolysis/ continuous extraction , Proc. Energy from Biomass and Wastes V I I I , Chicago , IL , IGT , pp 11 / 1 9 8 ( 1984) and references . . - . . therein G. , R., new CONClN *» BOBLETKK , o. Hydrothermal; sis: A process for the utilizatu ; of biomass , Wood Sci. Technol. 17: 195 202 (1983) and references therein. SARKANEN , K. V. Delignification of lignocel lulosics in organic solvents , Progress in Biomass Convers ion , edited by K. V. Sarkanen and D. D. Tillman , Academic Press: New York , v. 2 , pp. 127 44 (1980) and references - 3. - - - - BONN , 4. therein. CHUM H. L., DOUGLAS , L. J., FEINBERG D. A. & SCHROEDEK , H. A. Evaluation of Fretreatments of Biomass for Enzymatic Hydrolysis of Cellulose , SERI /TR 231 2183 , Golden , CO: Solar Energy Research Institute . . - - (1985). 5. CHUM , H. L , PARKER , S. K., FEINBERG , D. A., WRIGHT, J. D., RICE, P. A., SINCLAIR , S. A • • 6 GLASSER , W. G. The Economic Contribution of Lignins to Ethanol Production from Biomass . SERI / TR 231 2488 Golden , CO: Solar Energy Research Institute (1985). 6. CHUM , H. L., RATCLIFF , M., SCHROEDER , H. A., SOPHER , D. W . Electrochemistry of biomass derived Materials. I. Characterization , fractionation , and reductive electrolysis of ethano 1 ex tracted , explosively depressurized aspen lignin , J . Wood Chem. Technol. 4(4): 505 32 (1984) and references therein. 7. LUNDQUIST K., OHLSSON , B. ti SIMONSON , R. Isolation of lignin by means of liquid liquid extraction , Svensk Papperstidning , 78(11): 390 1 (1975). 8. ROBERT , U., GAGNAIRE , U. Quantitative analysis of lignins by carbon 13 NMR. Proc . Int ’ l , Symp. Wood and Pulping Chemistry , Stockholm , Vol. 1 , 8b 8 ( 1981). 9. FAIX , 0., LANGE , W., BEINHOFF , 0. Molecular weights and molecular weight distributions of milled wood lignins of some wood and bambusoideae species , Hoizforschung , 34(5): 174 b (1980) and references therein. 1 0 ROBERT. D., BARUET , M • » GAGNAIRE, D. Some studies about quantitative structural changes in lignins traced by carbon 13 NMR , Proc. Int * l. Symposium on wood and Pulping Chemistry . May 1983 Tsukuba Science City , Japan , Supplement Volume , pp. 1 4 (1983') and references therein. 11. CHUM , H. L., JOHNSON , L>. K. RATCLU K , M.. H.A.. BLACK , S• WALLACE , K • SCHROEDER ROBERT , K • • SARKANEN , K. V • • torchcoming publication. - - . - - - . - - - - - - - f # . - - 225 Table I. Lignin adhesive testing results in terms of: normalized average stress strength , S in psi and corresponding stan dard deviation , o8, and normalized wood failure , F, in X. - Level of Phenol Replacement 30% Cold Soak 50X 30% with Lignin P F S °s F S °s 702 52 668 55 626 68 37 48 59 57d 439 565 58 26 490 95 108 17 30 507 524 91 31 67 40 71 bO 58 50 Sweet Gum 657 721 681 77 70 110 60 521 653 624 92 65 34 530 485 555 93 103 74 Commercial Indulin AT KEAX 27 KEAX 31 696 673 707 61 b4 57 40 75 44 70 47 601 667 607 550 552 612 95 43 103 39 67 32 57 460 87 48 49 57 73 72 72 67 80 Type of Lignin S 0S - Steam Exploded Aspen MSESEAL EESEAL AESEAL Kraft Aspen Pine Organosolv Aspen 1b 40 35 87 90 38 40 64 39 16 17 29 522 561 549 500 38 44 48 58 J 0.04 M NaHS04 0.1 M NaHSO 0.05 M H2S04 0.05 M H3P04 658 664 63 98 672 77 641 71 50 47 600 581 499 54 597 100 81 Control 675 67 675 70 67 ^ 70 38 ^ ^ ^ day control , day) * 5control , year ’ where Scontrol , years the testing average of all controls over the entire duration of the test. Wood failure is a very subjective number. Arbitrary numbers were selected and all average wood failures were normalized to the selected values Numbers of samples: 20 30 test specimens per test. . - - 1 4.0 k 8.0 \ o i O i 0 K z -A • Z * 1- 5 $ -a "" > — o-o 0.5 2.5 0 — t * 2.0 1.5 vs pH - Figure 1. Apparent number , weight , and z average molecular weights of acetylated organosolv lignins as a function of Lhe pH of the liquor at 40°C. 226 - - aspen REACTIONS OF GLYCOSIDLS WITH BORATE IONS AT ELEVATED TEMPERATURE Jan Janson PULP AND PAPER RESEARCH INSTITUTE OF FINLAND P . O . BOX 136 SF- OOlOl Insert the figure here . HELSINKI FINLAND ABSTRACT Simple glycosides were heated with sodium hydroxide and borate solutions . The borate ions acted not only as ii i generators of hydroxide ions , but also reacted direct with some glycosides , degrading them rapidly into aci - •i dic products . Even a weakly alkaline reagent such as borax degraded e . g . methyl a- L - arabinopyranoside much faster than did sodium hydroxide of the same concentra tion . Glycosides able to form complexes with borate ions were degraded faster than others by borate sol - In a series of experiments with a constant sodium ion concentration of 2.4 mol / 1 , methyl a- L- arabino- utions a t elevated temperature . ° pyranoside was treated a t 170 C with solutions of NaOH , NaBO INTRODUCTION When using sodium borate solutions as pulping agents ^ and mixtures thereof alone followed the rate equation derived by Lai ( 3 ) : k es with temperature . When some 1 , 2 - trans- glycosides ° much faster than could be expected from their content of hydroxide ions . However , the alkaline hydrolysis of 1 , 2 - trans - glycosides is thought to proceed with the assistance of an ionized hydroxyl group a t C ( 2 ) . As a ^ consequence , the rate of hydrolysis a t a given tempera - ture and ionic strength would be expected to depend only on the hydroxide ion content of the solution , regardless of the presence of other nucleophiles . This discrepancy between theory and experiment motivated a closer look a t the interaction between borate ions and glycosides at elevated temperature . . c ( 1 ) , i t is important to know how their alkalinity vari - were used as indicators of the hydroxyl ion content of borate solutions at elevated temperature ( 100 - I 70 C ) , these solutions were found to degrade the glycosides . The action of each reagent where k obs » b, C b ra 2 is the observed pseudo - f i r s t order r a t e the concentration of the alkali used and a constants . Experiments were also carried out obs constant , C b and in^ which the concentration of one reagent ( NaOH or NaBO ) was kept constant and that of the other one ^ varied . In aqueous solution NaBO different ways as follows : . m B0 “ * ( n+I ) H ^ is protolysed in ( .* ) m- 1 OH 20 t Bm 2mH * ( H20 ) n ° ( = m * B ( 0H ) “ ) Referring to the borate species on the l e f t as the base and to the borate species on the right as the RESULTS acid , i t appeared that both the acid and the base , as Alkaline hydrolysis of the glycosides was studied by heating samples with solutions of various composition In sealed autoclaves a t 170 C , followed by deioniza tion , evaporation , acetylation and gas chromatography . well as the hydroxide ion , degraded the arabinoside , ° Isomeric glycosides were used as internal standards . Preliminary experiments showed ( figure ) that sodium borate solutions with sodiumiboron molar ratios between 0,5 and 2.0 degraded methyl a- L - arabinopyranoside at 170 °C a t a much higher rate than did sodium hydroxide solutions of comparable concentration , even though e . g . borax ( Na ( pH 9 O ) solution is only very weakly alkaline ^^ a t room temperature ) . the action of the acid being especially strong . To shed further light on this phenomenon , the four methyl glycosides of each L - arabinose , D - xylose , D galactose and D- glucose were subjected to hydrolysis a t i 70 °C . ^ I t appeared , that those 1 , 2 - trans - glycosides that with NaOH and with NaBO form strong borate complexes 1 n paper electrophoresis also degrade rapidly in borate solutions , e . g . a- L arabi nopyranoside and 0- D - galactopyranoside . Also , the very low stabilities of p- D - xylo- and - glucofuranosides towards hydroxide observed earlier ( 4 ) were matched by 227 similar low stabilities towards borate Ions . On the - . other hand , 1,2 cis glycosides were generally less affected by borate REFERENCES 1. . Pulping processe based on autocausticizable borate Svensk Pa p erstidn 83 ( 14 ) : 3g 2 - 395 ( 198 Janson , J : - The mechanism of the borate induced hydrolysis of . One possible explanation might be that formation of a borate complex e . g . from the glycosides i s unknown hydroxyl groups at and ( C ) that can undergo hydrolysis via alkoxide ion at . Ballou, C .E . : in methyl a-L - arabino- pyranoside , changes the equilibrium between the two 4 chair conformations 1 and Cjin favour of the one *^ 2 3 ^ Alkali - sensitive glycosides . Advances i n carbohydrate chem 9 59 - 95 ( 1954 ) Kinetic evidence of anionic intermediates in the base catalyzed cleav of glycosidlc bonds in the methyl D gluco pyranosides Carbohyd . Res 24 : 57 65 ( 197ZT: - assistance of an . - CONCLUSIONS The sensitivity of certain glycosidic links towards 4 . Janson, J. - alkaline borate solutions might help explain the behav iour of wood polysaccharides in kraft or hydroxide pulping involving borate liquors of the composition . Lindberg , B : NaBO pulping alkali . . . . ^ Time at 170° C , h H y d r o l y s i s r a t e o f m e t h y l a - L- a r a b i n o p y r a n o s i d e a t 1 7 0 °C w i t h v a r i o u s a l k a l i n e s o l u t i o n s 1 M NaOH 1 M NaCI O 0.25 M Na 2 B 407 V 1 M NaOH 1 M NaB 02 1 M NaB 02 O 1 M NaB 02 + 1 M NaCI x 1 M Na 2 B 407 228 - . .- Alkaline hydrolysis of glycosidie linkades V The action of alkali on some methyl furanosides . Acta Chem. Scand 14 ( 9 ) : 2052 - 2C £n T96ffT ( i.e . Na BO ) in place of NaOH as the ^ ^ aim of autocausticizing the main alkali source with the NaOH - . ^ . Lai , Y . Z .: . . ( -- 1 M Na 2 HB 03 ) ' Polysulfide was present in signif icant but rela tively low concentrations as compared to typical polysulfide cooking liquors and was formed as a result of a partial air oxidation of sodium sul fide , catalyzed by the residual organic matter present , under the conditions of calcium INFLUENCE OF DIVA'ENT METAL SALTS ON ANTHRAQUINONE PULPING - MICHAEL S. STELTENKAMP CHAMPION INTERNATIONAL CORPORATION - - P. 0. BOX 87 CANTONMENT, FLORIDA 32533 hydroxide causticization. It was demonstrated that soluble forms of calcium , probably intro duced into the final cooking liquor as soluble organo metallie salts , played a synergistic type role in the polysulfide catalyzed stabilizatio n of carbohydrates from alkaline degradation. - - Abstract Small levels of calcium hydroxide resulted in a . - in pulp yield when applied with anthraqui none in an alkaline pulping system , The effect was observed with other divalent metal cations " but was most pronounced with calcium hydroxide. The benefit obtained is attributed to the abil V ity of calcium and other divalent metal salts to catalyze a more selective formation of alkali stable acid end groups which provides for a I greater stabilization of carbohydrates from al kaline degradation. gain - - - Key Words: - Anthraquinone , Carbohydrates , Metal Cations , Alkaline Pulping - Aqueous calcium polysulfide solutions have been shown to have a greater stabilizing effect on •• • hydrocellulose than corresponding sodium poly sulfide solutions.( 2 ) It has also been previ ously shown that calcium hydroxide can enhance the effectiveness of polysulfide in one-and two4 -« % stage polysulfide pulping processes. - system. The Hydropyrolysis process( 1 )consisted of the heating of kraft black liquor under pres sures in the presence of water and in the ab sence of oxygen to a temperature sufficient to convert the organic material to a carbonaceous insoluble material. Approximately 90% of the orqanic material present in the black liquor could be converted to the insoluble and carbon aceous form while 10% , consisting mainly of low molecular weight organic acids , remained with the filtrate. The filtrate was subsequently causticized and used in the alkaline pulping process. - - - - - The kraft pulping liquors qenerated via Hydro pyrolysis were found to provide significantly higher pulp yields per given lignin content when - used in the cooking of a Southern pine wood fur nish than did the pulping liquors generated from conventional chemical recovery , We later estab lished that the yield increase resulted from an increased stabilization of carbohydrates towards alkaline degradation , catalyzed by the combined and interactive effect of polysulfide and calcium - - - *^ This ability of calcium to enhance the stabilization of carbohydrates towards hot alkali treatment is believed to be due primarily to its acceleration of a stereoselective rearrangement , of the benzilic acid type , of a ketoaldehydes into al kali stable aldonic acids. Glucosone , a probable intermediate in the polysulfide catalyzed oxida tion of glucose , gives preferentially gluconic and mannonic acids when treated with calcium hydroxide , while treatment with sodium hydroxide gives preferentially arabinonic and erythronic acids which are less stable in hot alkali mediums.(4,5,6) - - During the 1970's, St. Regis Corp. developed the Hydropyrolysis recovery process as an alter native to the conventional Tomlinson recovery - - - Introduction ions. - - This marked catalytic effect of calcium hydrox ide observed with polysulfide treatments would therefore seem to be related to observations previously made by others ; the effectiveness of calcium , barium , and strontium hydroxides in accelerating the conversion of phenylgloxal to mandelic acid which involves an intramolecular Cannizzaro type rearrangement ,( 7) the improved catalysis of the benzilic acid rearrangement by alkaline earth metals relative to that obtained with alkali metals(8 ,9), the requirement for zinc in the glyoxylase enzyme system which catalyzes a reaction very similar to an intramolecular Cannizzaro rearrangement ( 10 )and , the preferential formation of mannonic acid when either calcium or barium chloride is present in the reaction of glucose with 2 anthraquinonesulfonic acid. ( 11 ) - - - - - - In each of the above cases , the effect of a diva lent metal cation on the fragmentation and/or re - arrangement pattern of carbohydrates has been - 229 1 documented. In view that such rearrangements can impart a stabilizing influence on the carbo hydrates toward alkaline degradation , it was of interest therefore to expand our evaluation of calcium polysulfide pulping to include not only the study of other divalent metal salts, but to also include other pulping additives which pro mote a stabilization of carbohydrates through an initial oxidation step similar to that catalyzed by polysulfide. Of particular interest was the study of the effects of calcium and other diva lent metal salts with anthraquinone additive - - - - ! enhancing effect resulted from the combined ad - dition of the quinone and the divalent metal salt relative to kraft cooks where either AQ or calcium hydroxide alone were applied. - Pulp yield increases of 2 3 percentage points were obtained relative to kraft pulping over the unbleached kappa range studied when both Ca + + and AQ were employed while yield increases of 1 2 percentage points were obtained when only - AQ was applied. pulping. The objectives of our studies were to increase our understanding of the effect of metal salts on carbohydrate chemistry as it relates to alka line pulping and , to search for methods by which the cost effectiveness of pulping additives such as AQ could be improved. - Results The carbohydrate stabilization effect resulting from the introduction of small levels of anthra quinone (and polysulfide) to an alkaline pulp ing system is ascribed to an oxidation of the aldehyde end group of the starting aldose with formation of a carboxylic acid end group. With AQ , the amount of aldonic acids corresponding to end group oxidation increases while a lower yield of alkaline stopping acids is obtained.( 12) As with polysulfide pulping , the formation of aldonic acids catalyzed bv AQ presumably pro ceeds through an a ketoaldehyde intermediate. The dicarbonyl sugar intermediate then can pro ceed through either a hydrolytic cleavage reac tion to give arabinonic and erythronic acids or through a rearrangement which gives preferen tially mannonic and gluconic acid end groups. - - - - - - - - -- 4' - In view of the ability of calcium and other diva lent metal cations to accelerate the type of rearrangement characteristic of not only the stopping reactions but also the formation of stable aldonic acid forms, the addition of a divalent metal salt to kraft/anthraquinone pulp ing was anticipated to have a beneficial effect on pulp yields by accelerating those reactions - - - which compete with the so called peeling process. Using a Southern pine wood furnish , consisting Primarily of loblolly and slash , kraft pulping *,» s carried out with the addition of anthraqui rone (0.1% AQ on oven dried wood basis) and ca 1 rium hydroxide (0.5% Ca + + on O.D. wood ), Under otherwise typical kraft conditions, a yield - - - - - The Effect of Calcium Hydroxide Addition on the Pulp Yields Obtained in Kraft/AQ Cooks - - 230 Figure 1 - Comparison of the kappa and yield results ob tained as a function of cooking time indicated that addition of calcium hydroxide had only a marginal effect , if any , on delignification rates at the 0.5% application level. It was anticipated that the addition of calcium in the form of calcium hydroxide would have added to the total effective alkali concentration of the cooking liquor by contributing free hydroxide ions and thus , would have provided a slightly faster rate of pulping. This probably did occur to some degree but its extent is difficult to determine since the contribution to alkalinity would be dependent upon the solubility of calcium hydroxide which is constantly varying during the cooking cycle because of varying temperature , alkali concentration and varying concentration of complexation ions such as carbonate. If any improvement in rate was obtained , then our obser vation that no increase in the rate of kappa re duction occurred at the 0.5% Ca application would therefore indicate that a second effect slowed the rate such that it canceled any benefits ob tained from the contribution of free hydroxide - - ions. - i At higher levels of calcium hydroxide addition , the effect of the increased alkalinity was de - tected , as reflected by reductions in the kappa number. In the 0 1.5% range of applications studied , however , no adverse effect was obtained on delignification rates although it can be ex pected that application rates greater than those studied will in fact retard the rates. - be attributed to both the replacement of the divalent metal cation for the sodium ion and to the low solubility of some of the metal salts . - Figure 3 - The Influence of Various Divalent Metal Salts on the Ash - free Pulp Yields Obtained Figure 2 - The Effect of Calcium Addition at Various Levels on the Kappa Number Obtained in Kraft/AQ Cooking Kraft/AQ Cooking In the absence of anthraquinone , the divalent metal cations had no significant enhancing effec t on kraft pulp yields when determined on an ash free basis. This finding indicates that the gain in the ash free yield is not the result of a deposition of metal carbohydrate or metal lignin fragments onto the pulp , In addition , this result indicates that the observed gain » in pulp yields cannot be solely attributed to an acceleration of the " stopping " reaction which in volves the formation of a metasaccharmic acid via the benzilic acid type rearrangement of a diketone since this reaction would be occurring ( in both kraft and kraft/AQ pulping. - It has previously been shown that with a two stage polysulfide process, variation in cal cium concentration can influence the pulpi ng ( rate. 3) Lower levels of calcium hydroxide re sult in a small acceleration of delignification while higher levels retard the rates, The lat ter is probably a result of a decreased solubil ity of lignin caused by calcium complexation of 1 ignin. - - - - - To determine whether the yield enhancing effect observed with calcium is unique to calcium or is characteristic of other metal cations , a limit ed screening evaluation was conducted , As evident from a comparison of the yield kappa relat ion ships, calcium was not unique in its abili ty to enhance the pulp yields from a kraft AQ / pulping process. Other divalent metals such as zinc , barium , strontium and magnesium all had a posi tive influence but to varying degrees, The mono valent lithium cation and the tri valent boron and aluminum cations showed no activity . - - - - Of the metals studied , calcium was most effec tive in enhancing the pulp yield when comparison is made on an equimolar basis. The pulp yields re ported were corrected for the ash content which was found to be slightly higher than for the control case. The increase in ash conten t can - - - - - - in - The greater effectiveness of calcium ions over other divalent metal cations appears to be relat ed to the ability of calcium to form strong - er complexes with carbohydrates. Analyses of the pulps generated from the digester cooks show that calcium was retained on the pulp fiber to a greater extent than the other metal cations after thorough washing. The order of apparent binding ability is in agreement with the order of bene fit obtained. It is noted , however , that the order of metal retention on the pulp fiber ob served in our studies does not necessarily corre spond to the relative affinity of the - i - - various cations for cellulose since our analysis did not take into account the difference in the solubil ity of the various salts , Differences in solu bility would thus result in a difference - - the concentration of available cation for compl ex at ion. This could explain therefore our in - 231 i observation that calcium was retained on the pulp to a greater extent than zinc despite pre viously reported results which show that the zinc has a greater affinity for cellulose than ( ) A comparison based on equimolar calcium. 13 concentrations of soluble cations may therefore reveal a greater enhancement in pulp yield re sulting from zinc cations relative to calcium ions. - - - - - While it is well known that carbohydrates pos sess the property to form soluble complexes with alkali and alkaline metals, uncertainty remains concerning the nature , stability and structure of such complexes, Interaction of the alkaline earth metal hydroxides with carbohydrates re sults in an increased solubility of the hydrox ide through formation of either an alcoholate , carbohydrate metal hydroxide or carbohydrate metal oxide adduct , The greater enhancement associated with the calcium ion over the other cations may be related to the critical ion size requirements for complex formation with the a dicarbonyl compound. - - - - Irrespective of the nature of the complex , a strong complex can result and such a complex can increase the rate of the benzilic , or Cannizzaro type rearrangement by either hindering the isom erization of the initial aldose and/or stabiliz ing the transition state of the hydride shift that is required in such a rearrangement , Based on the relative effect of the metal salts studied , the stability of the metal complex thus appears to be more important than the basicity of the metal hydroxide. - - - Conclusions The results of these studies have shown that the yield enhancing effect of pulping additives such as anthraquinone and polysulfide in alkaline pulping can be further enhanced through the com bined use of the additive with a divalent metal hydroxide. No significant effect on pulping rates occurred and the divalent metal hydroxides had no influence on yields from kraft and soda pulping when employed by themselves in the ab sence of either anthraquinone or related quinone. - - The benefit obtained is attributed to the corn plexation characteristics of the metal ions, which are not fully understood , but such metal - are known to have an effect on the fragmen tation pattern and the intramolecular rear range ments of carbohydrates. ions 232 - - - - While these results provide for an increased understanding of means by which such pulping additives can be made more effective , the feasi bility of the specific application of the diva lent metal cations for use in pulping is uncer tain. Of the metals evaluated , calcium was most effective and perhaps most practical for applica tion. In view of our belief that the addition of divalent metal cations in this manner provicfes a simple means to reduce the effective cost of yield enhancing pulping additives, investigation of the system effects of such additions is under way in our Pensacola facility , Patent protection is pending. Experimental Pulping experiments were carried out on a Southern pine wood furnish consisting of both slash and loblolly pine. The chips were screened . then thoroughly *blended and stored at 4°C until used in cooking. Cooking was conducted using a 2.5 ft " steam jacketed rotating digester (0.67 rpm). The digester contents were vented initial ly then heated indirectly with steam to tempera ture in 60 minutes. After cooking , the pulp was pressure blown into a blow chest then washed successively with three water washings, After each wash , pulps were dewatered by suction drain ing until a stable consistency was reached. 4 * - -- For cooks with black liquor fillback , a kraft black liquor of ^25% solids content was used. Total fillback corresponded to 7% v/v of total liquor volume, All cooks were carried out using a 5:1 liquor to wood ratio. - Pulp yields were determined on unscreened sam pies. Unscreened samples were fiberized using a Sprout Waldron disk refiner set at 0.02" plate clearance. The pulp samples were tested for kappa number and ash content (Tappi T 211m 58). Metal content of pulp and liquor samples were determined by atomic absorption after wet ashing with perchloric and nitric acids. - - Acknowledqements The author wishes to acknowledge R. L. Miller and G. C. Landry for their contributions, particular ly with the hydrooyrolysis filtrate pulping stud ies, J. N. Rockwell for his assistance in the analytical methods and J. R. Wood and D. E. Nutter for their constructive criticism of this manu script. -- References TIMPE , W. G. and WATKINS , J. J • » U. S. Pat. 4 ,208 , 245 (Sept. 7, 1978) 1. 2. 1 2. - 3. LE'MON , S. and TEDER , A • Effect of calcium ions in polysulfide pulping. Svensk Papperstidn 75(11) : 439 443 (1972) $ # - SZABO , I. and TEDER , A., Calcium polysulfide pretreatment in the stabilization of carbo hydrates against alkaline degradation. Svensk Papperstidn 73( 12) : 404- 409 ( 1970) - LOWENDAHL , L. and SAMUELSON , 0• Carbohy drate stabilization during kraft cooking with addition of anthraquinone. Tappi ( 17) : 549 551 (1977) 13. KOGA , R • * SHINOZAKI , Y. , MESHITSUKA , G., and TITANI , T., The sorption of metal ions by cotton cloth. Bull. Chem. Soc. Japan - 37( 7) : 931 934 ( 1964 ) - 4. LINDBERG , B. and THEANDER , O• » React ions between D Glucosone and alkali. Acta Chem. Scand. 22(6 ) : 1782 1786 (1968) - 5. - - SZABO , I. and TEDER , A. , Alkaline degrada tion of hydrocellulose oxidized with poly sulfide. Svensk Papperstidn 72( 3) : 68- 74 ( 19691 6. MALINEN , R., SJOSTROM , E• and YLIJOKI , J • 9 Studies on the reactions of carbohydrates during oxygen bleaching. Papper och Tra ( 1 ) : 5 12 (1973) # - 7. OKUYAMA , T. , KAZUMASA , K. and TAKAUYKI , F. , Salt effects on the intramolecular Cannizzaro reaction of phenylglyoxa 1. Spe cific acceleration by calcium ion. Bul 1. Chem. Soc. Japan 55(7) : 2285 2286 ( 1982) - - 8. PFEIL, E. , GEISSLER , G., JACQUEMIN , W. , and LOMKER , F. , Benzyl rearrangement and benzyl cleavage. Chem. Ber. (89) : 1210 1225 - ( 1956) 9. O'MEARA , D. and RICHARDS , G. N • 9 Mechanism of saccharinic acid formation. Part IV. Influence of cations in the benzilic acid rearrangement of glyoxal. J. Chem. Soc. ( 387) : 1944 1945 ( 1960) - 10. ARONSSON , A. , MARMSTAL , E. and MANNERVIK , B• 9 Glyoxalase I , a zinc meta 1 loenzyme of mammals and yeast. Biochem. Biophys. Res. Comm. 81( 4 ) : 1235 1240 ( 1978) - -- 11. VUORINEN , T • Alkali catalyzed oxidation of D glucose with sodium 2 anthraquinone sulfonate in ethanol water solutions. Carbohydrate Res. (116) : 61 69 ( 1983) # - - - 233 Recent reports ( 4 ) indicate dim hopes for new ACOS major oil discoveries whereby the flurry of drilling activity experienced in 1979 1983 has fallen sharply. The number of marginal finds and "dry holes " continue to drain oil company profits and largely discourage further research into locating new oil deposits , As a result - BY ACID HYDROLYSIS OF - ACCELERATED CATALYSED ORGANOSOLV MEATS WOOD LASZLO PASZNER AUGUSTO A. QUINDE AND MEHDI MESHGINI DEPARTMENT OF HARVESTING AND WOOD SCIENCE FACULTY OF FORESTRY THE UNIVERSITY OF BRITISH COLUMBIA VANCOUVER , B.C. CANADA , V6T 1W 5 alternate liquid fuels should loom high on the agenda for future development. - - Developments cel lulose to ethanol in the field have suffered long from marginal economics ABSTRACT Ethanol is rated as an important alternative liquid fuel since it can be readily manufactured by fermentation of sugars from renewable vegeta ble materials. Economical production of sugars - from perennial woody materials is complicated by the chemical and physical heterogeneity of these materials. Solubilization of the decomposition products requires multicomponent solutions to accommodate both hydrophilic (sugars) and hydro phobic ( lignin and extractives) products. The ACOS process (Acid Catalysed Organosolv Saccha rification ) uses an aqueous acetone solution and a minor amount of a mineral acid as the hydroly sis solvent and accomplishes up to 700 times faster hydrolysis rates than possible with dilute acid solutions at up to one hundred times higher acid concentration. A transient acetona tion ( isopropylidine formation ) is thought to be responsible for the high hydrolysis rates and near theoretical survival of the sugars. Appli cation of the ACOS technology to such diverse substrates as coniferous or hardwood sawdust , agricultural residues from sugarcane and fibers from grain production and processing indicate that the process treats all types of lignocellu losics equally. Hydrolysis of the bagasse and corn stower have the same effect on alcohol yield as tripling and doubling the land base , respectively , thereby creating more favourable economic conditions in these sectors. The ACOS process further allows introduction of some novel processing technologies in cogeneration of products such as vegetable oils , rubber etc. * - - - - - INTRODUCTION - Long term - future liquid fuel supplies con tinue to pose some serious questions. Interim supplies from petrochemicals , though apparently stable at the present time , are expected to decline as we approach the year 2020, and might bo Interrupted at any time , Another energy crisis is forecast for the late 80's. [ nt . Symp. Wood b Pulping Chemistry of presently available conversion technologies and the severe competition of prevailing low gasoline prices , Alcohol was introduced into the liquid fuel market only after government subsidies were assured. Customer acceptance of gasohol was largely affected by population con cerns over environmental issues rather thar better automobil performance whereby in 1984 gasohol (10% ethanol 90% gasoline blends) was sold in some 20 states at selected gas stations - in the USA and Mohawk Oil in Canada has embarked on gasohol marketing in Ontario. Gasohol sales reached 13.5 billion liters by 1983, up 90% from 1982 in the USA (7 ). A particularly strong impetus for alcohol use in gasoline blends comes from the 1984 U.S. EPA ruling (2 ) whereby a 91 % cut in lead content in gasoline will be required by January 1 , 1986. Of the 375 billion liters of gasoline consumed in the U.S., some 143.5 billion liters of gaso - line are affected. Lead replacement in leaded gasoline will require immediately some 18.6 billion liters of alcohol (assuming that 1 liter of alcohol is equal to 1.3 g of lead in terms of octane boosting power ) (2). If all the lead is replaced with alcohols ( methanol and ethanol ) alone an estimated 218 billion liters (172 million tonnes ) could be required to provide gasoline blends with the required octane rating. Ultimately , the level of alcohol usage by the refiners for octane boosting purposes will be set by the competitive pricing and availability of alcohols and other octane boosting agents ( aromatics , such as benzene , toluene and xylene , and methy 1 tert buty 1 ether (MTBE) ( l ). Thus the competitive position of alcohols as mere alternate fuels has now been radically changed to that of a higher value octane booster addi tive allowing speculations ( 3 ) that the alcohol price will rise slightly to a level which is - - - competitive with that of the proposed alternate octane boosters This puts new life into the -- . cellulose to ethanol prospects albeit completely new set of conditions. under a 235 Present federal and state tax breaks in the USA have helped in establishing ethanol as a Lead cost competitive component of gasoline , the to gasoline protect environment removal from is a farther significant impetus for increased use of ethanol as a lead substitute (octane enhancer) and alternate liquid fuel to reduce gasoline consumption , Gasohol with 10% ethanol is only the beginning in modified liquid fuels. Only minor engine adjustments will be required to raise the proportion of ethanol to 20 to 25%. It then appears that limits to ethanol usage are set mainly by availability of ethanol at a competitive price. Sources of Ethanol The subject of alternate ethanol sources and their respective economics has been reviewed widely ( 12, 13, 15). Due to increasing petro - chemical and gas feedstock costs , most ethylene conversion facilities have largely been shut down whereby again most of the commercial ethanol is produced by fermentative processes. For obvious reasons grain fermentation to ethanol has made fast advances to fill the ethanol supply needs which are created by shut down of ethylene plants. Grain fermentation has the advantage of simplicity of technology and that it has well established markets for its by products ( germ oil and stillers' grain ). How ever , due to the high grain costs the profit margins are thin on grain alcohol and the indus try is not viable without the by product credits (16 ). Presently only 2.3 billion liters of ethanol is produced from corn in the USA. The actual ethanol required to fill all the octane gap in the USA is about 18.6 billion liters ( 5 billion US gallons) per year. It would take more than 20% of the U.S. corn production to meet the total requirement whereas less than half would be required if an equivalent propor tion of the corn biomass (stower cobs and straws ) would also be processed. Cellulose to ethanol technologies have seen little innovation in recent years in spite of the fact that 1 ignocellulosics offer by far the highest potential as feedstock for alternate fuel ( ethanol ) and chemicals manufacture. Work seems to continue mainly in two directions viz. a ) acid hydrolysis and b) enzymatic hydrolysis. The Scholler Madison process has now been closely analysed ( 23 ) and a modified version of it , developed in New Zealand , is now proposed as a pilot plant for the British Columbia Interior ( Ouesnel ) (8). Reports on the low temperature hydrof 1 uoric concentrated acid hydrolysis - - - - - - - - 236 process, earlier researched by Canertech Inc £ Winnipeg , indicate some progress and good sugar yields and a pilot plant is proposed fQr Saskatchewan ( 15). pilot plant studiea by TVA ( 14) hydrolysis based and NYSERDA GEO Products are also underway and a 20 million liter ethanol facility is planned by the Partnership Virginia for Ethanol McKenny , Virginia based on southern hardwoods as feed stock (6 ). on Other acid - - Advances with enzymatic hydrolysis processes continue to be hampered by the need to delignify lignified tissues before enzymatic attack on Hopes on wide the cellulose can take place. scale selective enzymatic delignification of materials have substantially 1 ignocellulosic been tempered by recent reports indicating that the new lignin specific strain (Phanerochaete - - chrysosponum) does not only lack the required delignification power to treat softwoods but requires at least three weeks under sterile incubation conditions to remove 17 to 28% of the lignin from birch wood. The necessity to further remove lignin and mechanical disintegra tion of the chips before enzyme hydrolysis is expected to make this pretreatment economically prohibitive for hydrolysis by enzymes , It seems much more work will be required in this direc t ion. - - The concept of the " forest refinery " has now been widely evaluated (17, 18) and economic con - straints were calculated by SERI (10) for organ osolv delignification as a pretreatment for enzymatic hydrolysis of lignocellulosics. These evaluations were largely based on the data released by Katzen et c l. ( 19) and Diebold et al ( 11 ) relating to their organosolv (alcohol ) pulping process. By analysis , the process was found to be highly energy demanding as a pre treatment due to the added energy required for recovery of the solvent from the pulp. Accord ing to Chum et. a l. ( 10) the minimum economically viable plant size at which pulp feedstock could be produced for enzyme hydrolysis at a cost com petitive with other pretreatments , was 2000 tpd. This capacity is not exactly of the order of magnitude accepted as the average chemical pulp mill and is far in excess of the preferred ^ . - _ - 150-200 tpd . problems with 2000 tpd mills would small scale mills at arise Major from - securing adequate raw material supplies for con tinuous operation and the large transportation costs (collection costs) for raw material haul " ing. Further limitations of the Diebold et a 1. ( 1 1 ) process are its inability of d e l i q n i f y m g conifers and high density hardwoods . Tota 1 of lignocellulosics by the Diebold et a 1. (11 ) alcohol pulping process is modification substantial on only possible ( acidification) of the solvent a process which is covered by U.S. Patent No. 2 959 500 that issued to Schlapfer and Silbermann in 1960 ( 22). saccharification Total Organosolv Saccharification of Lignocellulosics by the ACOS Process Theoretically organosolv saccharification can be looked at as the ideal process that is capa - - ble to decompose wood into its chemical compo nents viz. largely monomeric sugars and lignin. By selection of a suitable water miscible simple solvent , simultaneous depolymerization of Paszner and Chang in 1983 (21 ). On recovery ( flash evaporation) of the solvent the lignin fraction precipitated out and was shown to have a molecular weight of between 300 to 4300 (Mw ). Further studies into the effect of solvent composition on the rate of cellulose (cotton 1 inters) hydrolysis have shown that at acetone concentrations higher than 80 per cent some carbohydrate derivatization chemistry unique (known to occur only on monomeric sugars under anhydrous conditions) became operative under the conditions normally used in this process, The benefits that accrued from increasing the sol vent concentration became substantial . They - both the carbohydrate fractions and lignin could con included phenomenal hydrolysis rates which were higher than those obtainable with concentrated ceivably remove the usual obstacles experienced in aqueous hydrolysis by the Schoeller/Madison processes where secondary condensation of the lignin creates substantial accessibility prob lens and therefore the sugar recovery is less , than 60% , typically around 45 to 50% of the theoretical. The saccharification power of organic sol vents depends largely on the acidity of the sol vent itself , its competition for acidic protons for catalysis of secondary reactions that can lead to unwanted condensation products of the solvent. To some extent , the solubility of the depolymerized lignin in the organic phase is also of importance. Thus in previous work with the Schlapfer and Silbermann ( 22 ) process it was found that while the system (acidified aqueous lower aliphatic alcohols which did not react with the acid catalyst used ) had high initial hydrolysis rates , total dissolution required several liquor changes to dissolve the crystal line cellulose. At the same time , extended saccharification in acidified aqueous alcohol solutions resulted in substantial conversion of the hydrolysed sugars to furfurals when the alcohol concentration was below 60% and yielded large quantities of diethyl ether and ethyl sulfate among other reaction products. Unexpectedly , all these problems could be eliminated by Chang and Paszner (9) when ketones were substituted for the alcohol as the organic sol vent . Particularly fast hydrolysis rates were obtained with acidified aqueous acetone solutions whereby at 200* C in 60% acetone solu tion Douglas fir wood could be dissolved in 16 18 min depending on the acid concentration. The sugar recovery ranged from 68 to 74% with traces of furfurals present on total saccharification without. a liquor change , The process was cover ed by U.S. latent No. 4 409 032 that issued to mineral acids and 700 times greater than that obtainable with dilute acid at hundred times the - - - - - - acid concentration. For the first time , we could recover theoretical amounts fo reducing sugars from our hydrolysates without traces of furfurals. Temperature became the only kinetic parameter by which the rate of dissolution and sugar survival could be regulated. Some kinetic plots for cotton linters are presented in Figure 1 , where the effect of solvent composition , acid FIGURE 1 . RATES OF SUGAR SURVIVAL ON HYDROLYSIS OF COTTON LINTERS BY THE ACOS PROCESS ••a I ~ IM • * •o aMotf s « **o ^ concentration and temperature are examined in terms of amount of substrate dissolved and per cent sugars recovered , These results became the basis of another U.S. Patent No. 4 470 851 which issued in 1984 ( 20). Reactor throughput is substantially affected by the rate of dissolution and liquor residence time during the hydrolysis process , The allow able liquor residence time, on the other hand , reflects the stability of the dissolved products but has a considerable effect on the production economics since it controls the so 1 vent to wood ratio required for total dissolution of the sub - - - 237 . strate The composite data in Table 1 indicate the effect of acid concentration , and reaction temperature on . hydrolysis the rate and . nc» sugar lou I CFFCO y KID CONCfffUtlON MO >1ACT ION TUTIUTu * IRi Alf*N* ON TXf KYDR01YSIS MT ( ML SUGAR SUtVIVAi 0 OF CATION lIff!IS Rf ACTION Tf* •c OlSSOtVLD aumosc I * a 7® 79 210 n Tin *,$0« 13 23 S7.7 301 0 93 IK 7 S 8 1 % 3 no SO 7S 710 SC 7S 7* I*.I * 7.0 . S 7 i* 1 7» SO 7S 17 7 710 SO 7S b 9 720 SO 7S 3S S • * 91 S 73. S 93.0 * • 75.7 39 7 93 0 7% 7 1 - - -- -. i iio»ao» H i D t M TioRw « « Hoaa ( a 'CI H oi • OF WOOD SUGARS * * acetone:water. 7S 7 • 730 6S9.9 7S 0T£ SOivtar* B 23 Ktuxm (unT. L/M Q 1 1 99 0 19 S - Thus ultimate sugar concentra tions in the aqueous hydrolysate exceed 25% when II 0 total liquor to wood ratio is under 15:1 making these hydrolysates eminently suited for use in continuous survival of cotton linters. It can be seen that at low acid concentration (0.0235%) between 50 to 75% of the substrate can be dissolved without virtually any loss of sugars. The high hydrolysis rates and sugar survival in the ACOS process are due to the unique sugar solvent complexes which form at high solvent concentration. These complexes , known as ketals or isopropylidines, appear to prevail even at high temperature, Their formation may involve conformational changes at end units of the celluiose thereby weakening the glycosidic bonds against hydrolysis. The presence of these complexes in solution have now been proven by eas chromatography. Since isopropylidines of different sugars have different physical proper ties ( volatility, solubility and stability in acid medium ) properly stabilized hydrolyzate solutions can be worked up in a manner which allows facile separation of the pentose and hexose sugars as a primary option or alternately isolation of each of the five individual sugar species in wood is achievable by use of this chemistry In bulk processing of the hydro lysate , hydrolysis of the sugar acetone corn plexes is obtained by brief boiling in a weakly acid medium for 20 min. Some possible isopro pylidine structures of cellulose are presented in Figure 2. A particular advantage of the ACOS process is the fact that on removal of the solvent from the hydrolysate the dissolved sugars are automati cally concentrated some five times if the solvent was 80:20 and ten times if the solvent was 90: 10 with respect to the ratio of - - . - - - , 238 Cl F I G U R E 2 . S O M E A C E T O N E ( K E T A L) D E R I V A T I V E S 9 0 % 3 . I aa Ml 71 N * Ne a o i . t , ,i »/ ; * S 0 7S 0 36 -- ot o n IX 13 I 2.7 1 M* CI 9fc n *0 9 .? 0 XS N CO. Q25S 1» mSO, - t o SUGARS 91 * I0.0NS X ) n so - •- . vouciv 1 S * so SO ios * 10190 li so 0 01 ir VACUO MIC Mia 00 im VACTI0» fermentation/distillation such as the BROSTIL and others. processes The lignin is normally recovered as a light brown powder , free of carbohydrate contaminants, - low in ash and having a weight average molecular weight ( ) of about 1800 to 2300. This lignin Mw is soluble in alkali as well as the usual lignin solvents ( acetone , DMSO , THF , chloroform , alco - hol, etc.). Applications of the ACOS Process From the foregoing it should be clear that the ACOS process must be viewed as a stand alone - chemical technology with unparalleled capabili ties for simultaneous hydrolysis and decomposi tion of 1 ignocellulosic materials to component - monomeric sugars , lignins , and other extraneous products. Under suitable arrangements, recovery of the component chemicals is quantitative and the hydrolysis is complete. Separation of the r pentose and hexose sugar fractions , if desired , can be done either on basis of the physical properties of their acetone derivatives or by internal reactor arrangement , Short solvent retention times within the reactor and the pro tective effect of transient acetone complexes effectively prevent degradation (dehydration) of - sugars and secondary condensation of the sugar dehydration products ( furfurals ) to in fusible by products. The ACOS process was found to be effective equally on all types of 1 ignocellulosic mate rials thereby being ideally suited for mixed residue hydrolysis/processing , In this context wood residue hydrolysis could establish itself the - - - major forest products industry equal or substantially greater than the pulp and paper Canada alone disposes of some 200 sector. million tonnes of wood waste per year in its The forestry and forest products operations. potential alcohol yield , at 400 liters per as a tonne, would be 80 billion liters. This amount of alcohol is about four times that required for There is the gasohol market in the USA in 1986 . ample uncommitted capacity for growth and export of ethanol which could be opened up by this pro cess. It is also important to note that since there are no wood quality criteria to fulfill in ethanol production , the ethanol industry would not be competing for wood raw material with the hectare to 9, 150 liters per hectare on hydroly sis of the corn fiber , cobs and stower besides substantial quantities of xylose and lignin which could be marketed separately. IMlI : FOUNT IAl [ IHAJM » 1110 YULO . W M Souaci - .' Suuuu , ifc / t Tu ID I , COM AMI ninths / ao1 * l Turn, t /l IMAM ( i>a 04 * <4 aaa '$«6 l/ HA aaa a V% llAiaia Ufit 1/IU a V% lb ia loaa La» 3 2 VO abS Sift 910 0 /1 /b 9 in V0 ’ -V A IS TV 211 loaa SIOMB V in 1 W4 1 Ml l aa loaa as r> no sw7 90) v '4b /m 9 iso a.oo loaa tinii . . .. . 1 SI Me* oa fi ? . laciuoiat HIM mum .•••• SI10 11 loaa PLABI fama loa ItOat I • 9/ t existing lumber and pulp and paper industries. Therefore it would actually contribute signifi cantly to better utilization of the renewable baa i a Siau Poo lia Fat ' FIMI SwfcAJ At* , ... ••• 77.0 I loa C ! .. t I iiaia t Paotiia At* I I . .V ... 5 / 11 01 la 0 I aoI .. . 2.0 I SUM a CILLULOU .. 91. lI S lbaicm.ia. btl Lifaaia Paori ia At* Wiaii i l/ S ... lfc 0 t ... 11 0 I . 10I ... / 0 1 , - forest base in Canada and elsewhere. Some calculations with respect to alcohol yields from sugarcane processing reveal the startling fact that the ethanol yield can be doubled from 5 ,600 liters per hectare to 10,880 liters per hectare if advantage is taken of the glucose locked up in the extraction residue bagasse. Normally , the leaves and cane tops are burned off/severed in the fields. Including these residues together with the free sugars and bagasse in the cane biomass destined for hydro lysis would effectively triple the potential ethanol yield per unit harvesting area to 16 , 130 liters per hectare as evidenced in Table 2. The . - Preliminary calculations of ethanol costs by the ACOS process indicate that alcohol costs would range around 33$ per liter from wood /saw dust without by product credits from plants of 300 tonnes per day feedstock capacity. With by product credits with allowances for lignin , mixed fertilizer and methanol , the production cost would be 21 $ per liter for the same size plant. At the current price of § 450 US per tonne of ethanol (or §0.480 CDN per liter ) the breakeven plant capacity is about 100 tonnes per day for a non credit rated and 50 tonnes per day for a credit rated operation. With high capa city plants (600 to 1 ,000 tonnes per day ) the credit rated production cost of alcohol is lower ( 13 to 16$ per liter ) than the current price of methanol ( §0.20 per liter ). - - - - - - - tUli 7 . POTENTIAL CTMYl AECOHOL YIELDS FR01 SUGARCANE COUVERSK BY THE ACOS PROCESS * F - OviN Obv YULO I/HA bMlN SUBSTRATE . CAM Jwtci 1 YlllO T / MA ONLY (80 > 7 . lota*. CAM ONLY 80 S. KMAISI naif 20 . UUGAAL 40.9 V CAM Blown* • tiMo iKiuMSi CAM. » % 9 ! MAIU $. A M) I f A V f i EIMAMOL YULO 70 5 600 21.2 136 10 880 11.2 26$ S 300 20.2 243 9 817 30.4 168 16 128 . CONCLUSIONS Alternate fuel technologies have come of age EIHA MX YuiO l / IU with the USA requiring 18 billion liters (4.7 billion US gallons) of ethanol to satisfy the needs of its growing gasohol industry in 1986. Total lead replacement in gasoline could require ten to twenty tunes this amount within the next decade. Cellulose to ethanol technology developments were sluggish during the past decade for want of - - process does not only contribute to improved economics of alcohol production from sugarcane but also has the same effect as tripling the land base for energy related production of sugarcane. A similar situation can be demonstrated for As indicated in Table 3 the ethanol yield per unit area of corn peration can be doubled from 4 , 500 liters per - an economically viable and efficient wood hydro lysis process. Problems related to low sugar yields , low energy conversion ratios and high capital costs. None of the available processes were universally applicable to all cellulosic feedstocks. • thanoi production from corn. ° 239 The ACOS process is a universal wood hydroly - process that shows excellent hydrolysis rates and provides quantitative product yields on total hydrolysis of any 1 ignocellulosic feed stock . The process clearly separates a natural lignin and fermentable monomeric sugars , The solvent is recycled. Economic analysis of the process shows that ethanol can be produced by the ACOS process at relatively moderate plant capacities. The pro cess offers substantial profit margins on estab lishment of large capacity plants. Up scaled pilot plant testing is now underway in Brazil and under construction elsewhere. sis - - - 1984. Griffith , R.L. ethanol from wood. Sept. pp. 98 99. - TVA researchers Paper Trade • 1975. Katzen, R. Chemicals from NTIS Publ. PB. 263 489. - f ake ^ , Journal woodwaste. 1985. Klausmeier , W.H. Alcohol production exaggerated . C & EN, May 27, PP 4 5. - - Klausmeier , W.H. 1983. Biomass chemical s pro duction by thermochemical conversion , technology and Bioengineering Symp. No. Bio 13 pp. 81 97. -. - Klausmeier , W.H. 1982. Configurations for a forest refinery: an interim report. Argonne Natl . Laboratory , Argonne , Ill. 49 pp. Myerly , R.C• i M. D. Nicholson , R. Katzen and J.M Taylor. 1981. The forest refinery. CHEMTECH 11:186 192. # - Anderson , E. 1985. Lead cut gives alcohols a crack at gasoline blend market. C & EN , April 8, pp. 17 18. - . Anon. 1985 Lead limit in gasoline cut sharp C & EN , March 11 , P 8 . Anon. 1985. iy. - - - Anon. 1984. Domestic beaver ranch provides unique ethanol opportunity , Canadian Renew able Fuels Association. Renewable Fuels Report 1(4):7. Anon. - 1984. Virginia hardwood for first com mercial U.S. ethanol plant , Canadian Renew able Fuels Association. Renewable Fuels Report 1( 3 ):7. - Anon. 1984 , U.S. alcohol gasoline blend sales show 90% rise in 1983. Renewable Fuels Report (July 25) 1(1 )s 1. Anon. 1984. Sawdust mountain offers unique 20 cent/ litre ethanol resource. Canadian Renew able Fuels Association. Renewable Fuels Report 1(2):1 , 4 5. - - Chang , P.C. and L. Paszner. 1976. Recovery and GC analysis of wood sugars from organosolv saccharification of Douglas fir heartwood. Paper ' 76 Canadian Wood Chemistry Symposium, Sept. 1 3, Mont Gabriel , P.Q. 23 pp. - - . . Chum , H L., L.J. Douglas, D A. Fienberg and H.A. Schroeder. 1984. Evaluation of pretreatment of biomass for enzymatic hydrolysis of cellu 1 ose • SERI Report No. TR 231 2183, 66 pp. - - Diebold , V. B • » W.F. Cowan and J.K. Walsh. 1978. Solvent pulping process. U.S. Patent No. 4 100 016. Edelman , L.G • K.E. Eriksson and C. Johnsrud. 1981. Ethanol production based on ligno cellulosic materials. Rpt. NE/ BF 81 1. Swedish Forest Products Laboratory. 110 pp. # - -- . Garves, K. 1982 Ole und Chemikalien aus Holz und Ce 1 lulose. En Uberblick neuer Ergabnisse Holz Roh Werkstoff 40:41 44. . - - Paszner , L. and P.C. Chang. 1983. Organosolv delignification and saccharification process for 1 ignocellulosic plant materials. U.S. Patent No. 4 409 032. - Bioprocessing Technology 7(6):9. 1984. Anon. Behind big oil's slide from the peak to the pits. U.S. News and World Report , Dec. 17, pp. 62 63. 240 Paszner , L. and P.C. Chang. 1984. High effi ciency organosolv saccharification process. U.S. Patent No. 4 470 851. - REFERENCES Schlapfer , P. and H.C. Silbermann. 1960. Pro cess for saccharification of cellulose and cellulosic materials. U.S. Patent No. 2 959 500. Seaman , J. 1980. Assessment of dilute acid hydrolysis of cellulose. Bio Engineering '80 World Congress and Exposition. Atlanta , Ga., April 21 24. 6 pp. - memory capacity ( RAM ) is ca. 19 KB when DISK BASIC The image memory unit permits conver sion of an analog image to its digital image and its storage( 32 KB RAM ). The digital image consists of 256 x 256 pixels with 4 bit digitizing levels, i. e.. 16 - level greyscales. The " Digitizing Leve 1 Cord roller( DLC)"( Fig. 2) developed by the author permit.s extraction of characteristics from an object image on rea 1 - 1 i me is running. MICROCOMPUTER - BASED IMAGE PROCESSING AS APPLIED TO EVALUATION OF SURFACE PHENOMENA OF PAPER SHEETS AND PULP SUSPENSIONS Fumihiko ONABE Division of Pulp and Paper Science Department of Forest Products Faculty of Agriculture Yayoi University of Tokyo l - 1 - 1 , Bunkyo- ku, Tokyo, 113 JAPAN Abstract: A microcomputer - based system coupled with a means for visualization image basis without using software. That is, ( l )control of image contrast and black level ( i . e. , the lowest birghtness level ) ; (2 )select. ion of pseudo color processing video system and quantitative a provides ation of the static and dynamic surface digitizing levels evalu on paper sheets and in flowing pulp suspensions. Resume: Un systeme de traitement. d ' image base sur un micro-ordinateur associe au systeme video Image processing were compared des phenomenes statiques et dynamiques ( NEC faces sur les dans papiers et les A fibreuses en mouvement. . phenomena Paper sheets, Pulp suspensions. INTRODUCTION The recent a v a i l a b i l i t y of lower -cost. imagea memory (( D - RAM ) coupled w i t h a microcomputer system has made the d i g i t a l a laboratory scale. ' image processing possible This paper describes on the performances between of this system and 16 bit 8 - bit( PC800 I ) s PC9801 E:CPU 8086 ) microcomputers. Sof tware suspensions Keywords: Image processing, Microcomputer. Surface grey pseudo-colors. permet de visualization et evaluation quantitative sur - of scale digitizing levels( 2, 4.8. 16 ), and ( 4 ) reversal of digitizing levels of both greyscales and phenomena des (2, 4.8), ( 3 )selection series of w * re softwares developed using BASIC, although the machine language were used partly in repetit. ive parts of the programmes. This int.eractive( i . e., conversationaI ) system faci litates the development and modification of soft wares. Sequence of d i g i t a l image processing An analog picture of an object video camera and recorded on picture is freczed in 1 /60 a is taken video - tape The , second a by followed by design and operational experiences of t h i s system. Figure 2.: Digitizing Level Contro 1 l e r(DLC). METHODS Hardware The hardware system ( Fig. I ) is based on NEC's 8 - b i t microcomputer PC -800 1 ( CPU :Z80 ) w i t h user's PSEUDO COLOR VIDEO SIGNAL COMPOSITE VIDEO SIGNAL (R. G. B. VS. HS) IMAGE MEMORY UNIT Figure 1.: The Hardware System. * i FLOPPY DISK UNIT DIGITIZING LEVEL CONTROLLER a T V CAMERA JiT [ IMAGE MEMORY UNIT o- DIGITAL > ^PSEUDO COLOR v MONITOR > / DIGITAL > IMAGE CONTRAST ( l > k BLACK LEVEL CONTROL CIRCUIT PSEUDO-COLOR (2) DIGITIZING LEVEL BLACK K WHITE V MONITOR > SELECTION CIRCUIT LEVELS) (8 COLOR GREEN ^ PROGRAMMING v B/W HALFTONE (3) DIGITIZING LEVEL MONITOR SELECTION CIRCUIT ( 16 HALFTONES) VIDEO RECORDER EXTENSION UNIT (INTERFACES) PLOTTER f GRAPHIC DIGITIZER * (4) MICROCOMPUTER DIGITIZING LEVEL REVERSAL CIRCUIT FOR (2) K (3) PRINTER INDEPENDENT (5) IMAGE PREEZING (I) IMAGE INPUT ( II ) IMAGE PROCESSING * n t l. Symp. Wood & Pulping Chemistry SWITCH ( III ) IMAGE OUTPUT . i 241 digitizing. Then the characteristics of picture ore extracted using DLC followed by storage in a floppy disk. A histogram is first obtained for each digital image in order to see tion of greyscale of the image. level for binarization and the distribu A threshould method for noise removal are selected using the histogram and hexadecimal display of the digial image. Noise; removal i E IK I'D ' the Operational experiences of the system showed that the removal of noises from various sources are prerequisite for obtaining clear-cut digital images. The extent of noise removal required depends upon how an object image is contrasted D D t f rom its background. For poorly contrasted images, two countermeasures were taken to have clear cut digital images of « K t r - objects: ( i )adjustment of the level and contrast of video signals, and ( ii )conversion of the histo gram of original image to its narrower greyscale regions. Other smoothing methods for digital images are being tested. •c r w r Hig.3: I he hexadecimal display of ink penetration before noise removal . Two minutes contact of aqueous ink on a filter after paper 0 the lowest grey 1 evcl( b 1 tick ). F( 16 ) the highes t greyle vel( white). Noises on the backgr ound( HfCfl)vK ) are due to i NHOMO GENEI TY of i l l u m i n a t i o n on paper . = KXAMPLKS OF APPLICATIONS Practical applications of the system sheets: are presented. ( i ) Ink penetration into paper 1 he first example the evaluation is of ink penetration into paper, in which the contras t of an object image from its background(i . e. , white paper) is, in genera 1 , clear and no noise removal (ii) Floe formation and sedimentation of pulp suspensions: was The second example concerns the evaluation of A binarization of the image at certain consistency , sedimentation, and floe formation in greyscale level was sufficient to obtain a clear - flowing pulp suspensions, in which the contrast of required. cut image of the object. In thi6 experiment, ana log images on the of ink an object image( pulp) process penetration into paper both in twodimensional directi on(surface) and in z(thickne ss) direction were recorded on a video tape folI owed by digitizing using the system described above. The area of ink penetration was obtaine d by counting the number of digitized points ( I . e. , pixels picture elements) in the penetra tion a rea. I he penetration nature differed accordi ng to ( 1 )the homogeneity of paper( filter paper or hand made paper or machine mede paper), ( ) 2 the acidity in papermaking ( i . e. , acidic or alkaline), (3)the nature of inMi.e* , aqueous ink or oily ink ) , and (4)the nature of odditives( i e . , sizing agents and f i I lers, etc) The hexadecimal display of the penetration area is shown in Fig.3. - - - from its background(water and white paper) is not clear and noise removal was requird. Observations of these phenomena are based on the scattering of 1 ight by fine pulp f i bers( i . e.. "Tyndall effect ") In this case, the histogram conversion was performed to enhance the contrast of images. , CONCLUSIONS The technique described so far provides a means of non contact analysis and permits visualization - , and quantitative evaluation of s l i g h t differences in changes in static and dynamic surface phenomena on paper sheets and in p u l p suspensions Within the scope of the present work, the d i g i t i z i n g level (4 bits) and the resolution of the images (256 x256) are sufficient. Although the system w i t h higher d i g i t i z i n g I eve? Is and higher tions provides more detailed information object Image, the processing time and the resolu the system may increase considerably. 242 - on the cost of , and has subsequ ently been designa ted Iignina se H8 (4). Bovine erythro cyte superoxi de dismu tase (Worthing ton ), used for some electro n spin resonan ce ( ESR ) experime nts , was further puri fied by ion exchang e HPLC on the Pharmac ia Mono Q column (4). Superoxi de dismuta se activity was assayed accordin g to McCord and Fridovi ch (5). Chemica ls. 1 ,4 Dimethox ybenzene was obtained from Aldrich Chemical Co . The tet ra raethoxy benzenes were synthesi zed and purifie d as describ ed by Kersten et al . (6). Model I was prepared earlier (3 , 7 ), and model II was synthe sized accordin g to Hamme 1 et al . (8). 5 ,5 Dimethyl 1 pyrrolin e N oxide (DMPO) (Sigma ) was vacuum distill ed before use . All other chemica ls were reagent grade and used without further purifica tion . ESR Experime nts. ESR measurem ents were perform ed on Varian E 9 or E 109 spectrom eters. The operatin g conditio ns have been describ ed (6 ,8). The contents of the reaction mixtures are describ ed in the figure legends. Product Identif ication . The product s benzoqui none and methano l (as a derivati ve ) from oxidati on of 1 ,4 dimethox ybenzene by ligninas e were identifi ed by gas ch roma t ography/inass spectros copy (6). Content s of the reaction mixtures and techniqu es for product identif ica tion have been describe d (6). Incubati on conditi ons and methods for quantita tion and identif ication of veratra ldehyde and benzald e hyde from model II oxidatio n were accordin g to Hamme 1 et al . (8). Other Assays. Ligninas e (H8) was quanti tated by its absorpti on at 409 nm [L 168 mM - 1 • cm - 1 (9)]. Oxygen uptake was measure d with a YSI Model 53 0 , elect rode. - LIGNINA SE FROM PHANERO CHAETE CHRYSOS PORIUM: CATALYT IC PROPERT IES OF A NOVEL ENZYME T. KENT KIRK , MING TIEN , KENNETH E. HAMMEL , PHILIP KERSTEN , and B. KALYANA RAMAN -- FOREST PRODUCT S LABORAT ORY ONE GIFFORD PINCHOT DRIVE MADISON , VI 53705 U.S. A. - ABSTRAC T Ligninas e isolate d from Phanero chaete chrysosp orium catalyz es cleavage of p 1 and 0 0 4 lignin models between Co and CD of their p propyl side chains , and it also catalyz es a number of other oxidatio ns in various lignin rel.it ed compoun ds . Some of the reactions , includin g C C cleavag e , consume both and whereas others consume only H ;0;. Based on studies of the mechani sm of oxidati on of several substra tes , a un fied scheme tor ligninas e action on 1 ignin related compound s is propose d. . ^- ^ - KEYWORDS: Lignin biodegr adation , peroxid ase , hemrprot ein , cation radical s INTRODU CTION The recent discover y of the first lignin degr .iding enzyme ( 1 ,2) has opened the field of lignin biodegr adation to biochem ical inquirie s . Efforts are being made to clone the gene(s) that encode lignina se , and to underst and the enzyme 's mechani sm. This report summariz es our researc h on the mechani sm of ligninas e ; these investig ations have entaile d charact erizing the nature of the reaction s catalyz ed as well as studyin g reaction kinetic s , Our results indi cate that the wide range of substra tes attacke d by ligninas e , its apparent oxygena se activity (3), and the diversit y of reactio ns catalyz ed ( 1 3) can be explaine d by free radical formati on in the substra tes. - - - MATERIA LS AND METHODS Enzymes. Ligninas e was isolate d from Phancro chaete chrysosp oriurn Burd. , strain BKM F 1767 ATCCZ.4 725) (3) and purifie d by ion exchang e chromat ography using a Mono Q HPLC column from Pharmac ia (4). Ligninas e used in these studies is the same as that initial ly isolate d and describ ed by Tien and Kirk ( 1 ,3) -- Inti . Symp. Wood & Pulping Chemistr y - - - - -- - - - - -- - - - - - - - - = RESULTS AND DISCUSS ION Recent studies have shown that ligninas e - is a hemepro tein peroxida se ( 10). It is char acteriz ed as a peroxida se based on its spectra l propertie s (3 ,10) and on its requirem ent for H2 2 for catalysi s ( 3 ). Steady state kinetic studies have shown that the enzyme operates by a ping pong mechani sm (9). It first reacts with 1 0 to form a two electro n oxidize d interme diate. This interme diate then oxidize s the lignin substra tes and returns to the resting ( ferric ) state. Accordin g to the nomencl ature of Chance ( 11 ), the two electro n , H O. oxidized - ° - ^ ^ - - ^ ^ - 243 intermedi ate of peroxidas es is called Compound I . The 2 electron oxidation of substrate can occur sequentia lly , forming a one electron oxidized intermedi ate (Compound II). Based on the need to conserve charge , researche rs have proposed that formation of Compound 11 by peroxidas e is evidence for free radical formation in the sub strate ( 11 ), which is known to be the case with numerous peroxidase substrate s , Our work with stopped flow rapid scan technique s has shown that ligninase also undergoes formation of Compounds I and 1J during catalysis (9). The - - - - ^ formation of Compound 11 is important for under standing the mechanism of the ligninase . figure 1 shows the 1 IGNINAS E catalyzed cleavage of the C CD bond in 0 1 model I . o p Products are syringald ehyde methyl ether and 3 ,9 dimethoxy phenylgly col ; the latter contains a new hydroxyl group. In certain respects , the oxygenase activity of this reaction resembles the peroxide dependent hydroxy 1 at ion reactions catalyzed by cytochrom e P950 (12). In fact , Shimada et al . ( 13) have demonstra ted the oxida tion of a similar 0 1 model using a cytochrom e P950 model , tetraphen ylporphri nato lron complex plus tert butylhydr operoxide. But in contrast to ihe cytochrom e P950 system , the ligninase system incorporate s oxygen from dioxygen rather than H ^O into the hydroxyla ted diol product 2 2 shown in Figure 1 ( 3). Spectrosc opic results also demonstra te clear differen ces between - - - - - - - - - - • . cytochrom e P950 and ligninase ; the peak i n * the reduced CO differenc e spectrum of ligninas * is not at A 50 nm (19). The catalytic propertie s of ligninase are similar to those of lipoxygen ases and cycloxy genases (15). These iron containin g enzymes utilize dioxygen in their oxygenatio n reaction s and require peroxides for maximal activity. Because free radicals have been shown to be involved in catalysis with soybean lipoxyge nase , we tested this possibili ty with the ligninase . A free radical mechanism was also seemed to be attractive since ligninase catalyzes a number of seemingly disparate , nonstereo selective reac tions ( 1 3). Several substrate s were tested for free radical formation by ESR spectrosco py . Because each phenylpro panoid unit in lignin contains one or two aryl methoxyl groups , we initially tested simple methoxy substitut ed benzenes. As shown in Figure 2A , an ESR signal was detected in incubation s containing ligninase and H„0 with 1 ,9 dimethoxy benzene . The signal 2 2 was relatively stable at room temperatur e and was detected in the absence of a SPIN trapping agent . The free radical was subsequen tly identifie d as the cation radical of 1 ,9 dimethoxy benzene based on the gauss (g ) value and the hyperfine splitting constants ( hfsc ) of its ESR signal , This cation radical had not previously been detected in biologica l systems. Incubatio n with other methoxybe nzene congeners yielded equally intense ESR signals (6). Figures 2B and 2C show the ESR signals from the cation radicals of 1 ,2 ,3 , a n d 1 ,2 ,9 , 5 tetrameth oxybenzen es , respectiv ely . The mag netic parameters of these two radicals agree well with the literatur e data reported for the correspond ing cation radicals generated chemi cally ( 16). No ESR signal was observed with 1 ,2 d imet hoxybenze ne , although IJV spec t rophoto metric results clearly show that it is a sub strate. Radicals from penta , 1 ,2 3 ,5 , tetra * and tri methoxybe nzenes were also not detected . Activity was no! restricte d to the methoxybe n zenes ; ESR signals were also observed in incu bations containing 1 ,9 diethoxyb enzene. We attribute the stability of the methoxy benzene cation radical to the low pH of the ligninase reactions| pH 2.5 is optimum ( 3)1 , - - - - - - - - - - Figure 1 . »• - Reaction scheme illustrat ing the products and isotope labelling - pattern from 1 IGNINASE catalyzed cleavage of model I. Syringalde hyde methyl ether is formed from the lower ring and a diol is formed from the upper ring. The oxygen atom inserted into the 0 carbon (benzylic carbon of the diol prod uct ) is derived from dioxvgen. The diol can be further cleaved by ligninase (see (9) for further details). - - 244 - - - - - - - - - - - - - which stabilizes such radicals , and to the num ber and positions of the methoxyl groups , The oxygens have two types of effects on the radicals: resonance and inductive , The resonance effects from the lone pair electrons tend to stabilize the radical . In contrast , the inductive effects ( from the electronegativity of the oxygens) tend to destabilize the positive charge of the cation radical . Thus an ESR sig nal is observed with 1 ,4 dimethoxybenzene ( favorable charge distribution), but not with 1 ,2 dimethoxybenzene. - - - - shows a hypothetical scheme for benzoquinone and methanol elimination which is consistent with our results. Methanol was also formed from the ligninase catalyzed oxidation of 1 ,2 dimethoxybenzene , suggesting a similar mechanism of oxidation even though no stable free radicals were detected . - - Although methoxyl loss in lignin does occur during fungal attack (18), suggesting that hese ^ activities may be operative in vivo , demethoxyla tion by ligninase is a minor reaction in lignin models. The predominant biodegradative reaction of lignin and in lignin model compounds is C C0 a p cleavage of the propyl side chains (3 , 18 , Kirk et a_l . , unpublished), To test whether free radicals are involved in this important reaction , we examined several dimeric models of lignin . - - r OCM OCH, , H0 •• - M OC*, , OCH B - 0 0 , M C0 , M C0 c , y v c> >M Hf° OH 7 M* MM Mr* OCH Figure 3. , OCM Hypothetical scheme showing two sequential one electron oxidations of 1 ,4 dimethoxybenzene and additions of water with elimination of methanol . The incubation of model II with ligninase and veratraldehyde and benzaldehyde 2 2 QUANTITATIVELY in a 1 : 1 stoichometry . During catalysis , an ESR signal is observed , but only in the presence of a spin trap such as DMPO. Radicals with half lives too short for direct detection can be stabilized by reacting with DMPO to form a more stable spin adduct . The g values and the coupling constants from the protons of DMPO are affected by the nature of the parent free radical ( 19). Thus these parameters yield information on the structure of the trapped free radical . The g value and the hfsc of the signal from the incubation of model II with the ligninase under anaerobic conditions are indicative of a carbon centered radical (Fig. 4A ). When oxygen is allowed into the incubation , the signal intensity of the carbon centered radical is diminished and a new signal appears ( Fig . 4B). The g value and hfsc of the new signal resemble those of a peroxy radical (8). Since it is the - - ^^ ML 84 5680 Figure 2. ESR spectra of cation radicals of methoxybenzene congeners. The 2 ml reaction mixtures contained 0.5 pM ligninase , 0.32 mM H , 0.1 M sodium tartrate pH 2.5 , and 5 mM of either 1 ,4 dimethoxybenzene (A), 1 ,2 ,3 ,4 tetramethoxybenzene ( B ) or 1 ,2 ,4,5 tet ramethoxybenzene (C). Reproduced from (8). The major products from l igninase catalyzed oxidation of 1 ,4 dimethoxybenzene are benzo quinone and methanol (6). This demethylating activity is unlike that of the O demethy 1 ase activity catalyzed by mono oxygenases , in which formaldehyde is produced ( 17). The products benzoquinone and methanol are quite consistent w i t h the known chemistry of cation radical decomposition in aqueous systems. Figure 3 - 20.7 - - - - - - - - - - - - - - 245 - beta carbon of p 1 models that is hydroxyla ted by dioxygen during catalysis (3), we suspected that the radical exists on this carbon , To test this hypothesi s , model 11 was synthesiz ed with 13 c: on the beta carbon , As predicted from the nur 1 ear spin of 13C ( 1 1/2), the ESR spectrum was lurther split into doublets ( Fig. AC). The ESR spectrum , however , also indicate d the presence of another radical which is carbon c ent ered . That signal , arising from the 1 2c centered radical , closely resemble s the signal ol the a hydroxybe nzy 1 radical adduct and so probably represent s the nr hydroxy dimethoxy ben/.y 1 rad I ca 1 . In any case , these results nidi * ale that the cleavage reaction proceeds , at east in part , via the lornidtio n of a i . i i .. • red rad i ea 1 . = - - - - radical adduct of DMPO is a mixture of both superoxid e and alkyl hydroxyp eroxy radicals. This is not a surprising result in light of the known chemistry of alkyl hydroxyp eroxy radical s which dispropo rtionate to yield aldehyde s and supe roxide ( 21 ): OH 9 f RCOO * RCH H HOJ It is often difficul t to ascertain whether the radicals observed by ESR spectrosc opy are an integral part of a reaction mechanism or whether they are products of insignif icant side reactions . This i s because the technique is s« > highly sensitive , On the other band , because of the reactivit y of most rad K a Is rind t l » < high rate constants for competing reactions , it is possible that many times only a small frail ion of the radicals are trapped , To determin e whether the radicals are integral intermed iates , we conducte d product inhibitio n studies , If the radicals trapped by DMPO are intermedi ates formed in catalysi s , then DMPO should also decrease the amount of products formed , Th I s proved to be the case. Increasin g DMPO concen trations caused a correspon ding decrease in benzalde hyde formatio n ; the effect of veratral dehyde formatio n was negligibl e (8). These results clearly indicate that the radicals detected by ESR spectrosc opy are an integral part of catalysis and not formed via an insigni ficant side reaction. Free radical involveme nt in cleavage of model II is also consisten t with the stoichi oraetry of the reaction. As mentione d above , model II is cleaved by ligninase between C and ? Cp to yield veratra 1 dehyde and benzalde hyde (6). Because these products are not substrat es for further oxidation by ligninase ( in contrast to those from model 1 ), model II was also ideal for stoichiom etry studies , The stoichio metry under anaerobi c condition s showed that one veratral de hyde and one benzalde hyde are formed per H ,0 , and dimer consumed (6). Under aerobic condi tions , the products and the product ratio were the same , but sub STOICHI OMETIC amounts of H were consumed per dimer cleaved. The reac tion also required H ,0 ,. and resulted i n oxygen being consumed . This result , in which H.,0 , I s an - - figure A. ESR spectra of the spin adducts of reaction products from model 11. The 1 ml reaction mixtures contained 2 pm ligninase , 0.16 mM H , 0.16 mM model II , AO mM DMPO in 25 mM sodium tartrate pH 2.5 , under anaerobic (A ) or aerobic ( B&C ) condition s. * Carbon centered radicals can add dioxygen at rales limited only by diffusio n (20). Conse quently , we suspected the oxygen centered radical to be the correspon ding alkyl peroxy radic a 1 . Because this radical adduct would have the same hfsc as that of the superoxid e adduct , however , we tested the effect of superoxide dis mutase on the signal intensity . These react ions were performed at pH 5 , at which both superoxid e dismutas e and ligninase are active , Superoxid e dismutas e ( 20 units * ml 1 ) decrease d the signal intensit y hut did not totally eliminat e it . This result suggests that the oxygen centered - ^ - - - - - - 246 - - - - - activator , resembles the propagatio n s t a g e of a free radical reaction . F i g u r e 5 shows a scheme for c l e a v a g e of model II which is consistent with the results presented here , The initial reaction is oxidation of ligninase by t o form the t w o - electron oxidized C o m p o u n d 1 intermedia te of 1 i g n i n a s e . C o m p o u n d 1 oxidizes model II by o n e electron t o yield the o n e - electron oxidized ligninase intermedia te Compound II and a sub s t r a t e radical . O n t h e b a s i s o f t h e w o r k w i t h methoxybenz enes , w e speculate that the substrate radical is the cation radical , It breaks down t o yield v e r a t r a l d e h y d e and the a - hydroxyben zy 1 radical , o r alternative ly , benzaldehyd e and the or - hydroxy dimethoxybe nzy 1 radical , U n d e r anaerobic conditions , the radicals are further oxidized t o yield the correspondi ng aldehydes . The oxidant may be the C o m p o u n d II intermedia te of 1 igninase . Under aerobic conditions , the carbon - centered radicals add dioxygen t o yield the correspondi ng o - hydroxyl benzyl p e r o x y radicals which disproporti onate t o yield the aldehyde and the superoxide radical . T h e latter dismutates t o produce H O . We postulate that 2 2 this H 2C> - producing a c t i v i t y a c c o u n t s for the 2 less than stoichiome tric a m o u n t s of added H O 2 2 consumed under aerobic conditions . Chemically , the free - radical mechanism a c c o u n t s for several of the p r o m i n e n t r e a c t i o n s ot lignin biodegrada tion : C cleavage , loss ^ Cp of methoxyls , oxidation of benzylic hydroxyls t o ketones , and ring opening are mechanisti cally consistent with a free radical mechanism , We do n o t propose , however , that all of these r e a c t i o n s of lignin degradatio n are catalyzed by ligninase ; indeed , several other enzymes are also secreted by ligninolyt ic cultures of P . c h r y s o s p o r i u m ( A ), and o n e of those enzymes also has aryl demeth( o x )y 1 a t 1 n g a c t i v i t y in cer tain compounds ( 22 ). T h e mechanism proposed in this paper for oxidative C - C cleavage is in ^ accord with the work of Snook and Hamilton ( 23 ) on free radical oxidation of pheny 1 a 1 kano 1 s . Those workers demonstrat ed that the cleavage of 1 - o r 2 phenylalkan ols , of which model II i s a p a r t i c u l a r example , by Fenton ' s r e a g e n t or by p e r o x y d i s u 1 fate , p r o c e e d s v i a c a t i o n radical ^ - intermedi ates t o y i e l d benzaldehy de and the a l k y l radicals as products: PhCHOHR PhCHOHR e- - PhCHO R • * H*. OCH 3 Lignmose H 2 O2 Lignmose H* H* V k OCH3 Anoerobic Aerobic 02 I Liqninose0, P *' ^H e OHC 10 OCH 3 Oj+ H* ' X *Z 02 { 2 H2 2 / ° OHC 10 MltS Sin F i g u r e 5. Hypothetic al scheme for anaerobic and aerobic cleavage of model II by ligninase. Reactions of the or - hydroxy( dnnethoxyb enzyl ) radical , indicated a t the left with t w o arrows , are proposed t o be analogous t o those shown a t the right for the a - hydroxyben zy 1 radical . On the basis of our initial results with methoxybenz enes ( 6 ), and o n the results of Snook and Hamilton ( 23 ) w i t h chemical s y s t e m s and phenylalka nols , w e proposed that the v a r i o u s reactions catalyzed by ligninase involve a mechanism based on aryl c a t i o n radical formation (6 ). The fate of these radicals , we s u s p e c t , is determined by their structures ( i .e. by the sub stituents o n the r i n g ). We s u s p e c t , t o o , that some radicals a r e s o unstable that they do n o t diffuse away from the a c t i v e s i t e of ligninase and therefore undergo t w o rapid s e q u e n t i a l o n e electron oxidations . Other substrate s , like the ones studied here , a r e stable enough that the radicals c a n be detected directly by ESR s p e c t r o s c o p y . A radical mechanism is also c o n s i s t ent with the NONSTEREOS ELECTIVI 1 y ot the e n z y m e ( A ). A radical mechanism for l i g n m a s e catalyzed lignin degradatio n has also r e c e n t l y been hypothesize d by Shoemaker e t a [ . (2A ). These workers based their conclusion on the known metabolic fate of lignin model compounds and its similarity to the chemistry ot cation 247 radicals. The hypothesis (6 , 24) that cation radical formation is the basic reaction cata lyzed by ligninase is supported by our experi mental results , summarized here , It is thus becoming apparent that radical chemistry plays an integral part in lignin biodegradation , as it does in lignin biosynthesis. 12 . - - - 13. SHI MAI)A , M . , HABE , T. , UMEZAWA , T. , H 1 GUCHI , T. , and OKAMOTO , T. Biochem Biophys. Res. Comm . 122: 1247 1252 ( 1984 ) GOLD , M . H . , KUVAHARA , J . , CHIU , A. A. , and GLENN , J . K. Arch Biochem Biophys 234: 353 362 (1984) - - - M. J - 14. ACKNOWLEDGMENTS This work was supported in part by NSF grant PCM 8304123 and NIH grants GM 29035 & RR 01008. . WHITE , R . E. SLIGAR , S. C. , and COON J Biol Chem 255: 11108 11111 ( 1980) 15. RAINING , J . L. and AXELROD , B. 232: 193 202 ( 1958) Biol Chem - REFERENCES 1 . TIEN , M . and KIRK , T. K. Science ( Wash . DC) 221: 661 663 ( 1983) 16. - - 2. CLENN , J . K. , MORGAN , M . A . , MAYFIELD , M. B . , KUWAHARA , M. , and GOLD , M . H. Biochem Biophys Res Commun 114: 1077 1083 (1983) 4. - - - - 17. NETTER , K. J . and SEIDEL , G. Therap 146: 61 65 ( 1964 ) - 3. . 1 SHIZU , K. , WATANABE K. , and OHYA N 1 SHIGUCH 1 , H. In Landolt Borstein , ( Fischer , H. and Hellwege , K . H . , eds.) New York : Springer Verlag Group II , 9: 124 147 ( 1980) J Phar Exp - TIEN , M . and KIRK , T. K. Proc Natl Sci Acad USA 81 : 2280- 2284 ( 1984) 18. KIRK , T. K . , and CHANG , H. m. Hoizforschung 29: 56 64 ( 1975) - - KIRK , T. K. , CROAN , S. C. , TIEN , M. , MURTAGH , K. E • » and FARRELL , R . Enz and Microbial Technol in press (1985) 5. McCORD , J . M . and FRIDOVICH , I . Chem 243: 5753 5760 (1968) 19. JANZEN , E. G. 1 n Free Radicals in Biology (Pryor , W. A. , ed . ) New York: Academic Press ( IV ): 116 154 ( 1980) - J Biol - 20 . PRYOR , W . A. KERSTEN , P . J . , TIEN , M., KALYANARAMAN , B. , and KIRK , T. K. J Biol Chem 260: 2609 2612 (1985) 21 . BOTHE , E. SCHUCHMANN , M . N. , SCHULTE FROHLINDE , D. and VON SONNTAG , C. Photochem Photobiol 28: 639 644 (1978) 7. NAKATSUBO , F. and HIGUCHI , T. Holzforschune 29: 193- 198 x 1975) 22 . PASZCZYNSKI , A . , HUYNH , V. B . , and CRAWFORD , R . L. FEMS Microbiol Lett in press ( 1985) 8. HAMMEL , K . , TIEN , M . , KALYANARAMAN , B . , and KIRK , T. K. J Biol Chem in press 23. SNOOK , M . E • • and HAMILTON , G. A . Chem Soc 96: 860 869 ( 1974) 6. . - (1985) - J Am - 24. TIEN , M. , BULL, C. , and Fee , J . A . Madison , W 1 : Forest Products Laboratory . Manuscript in review ( 1985) SHOEMAKER , H. E. , HARVEY , P. J . , BOWEN , R. M. and PALMER , J . M. FEBS Lett 183: 7 12 ( 1985) - J . 10. KlIILA , D. , TIEN M. , FEE , J. A. , and ONDRlAS , M . R. Biochemist ry in press (1985) 11 . CHANCE , B. Arch Biochem Biophys 41: 416 424 ( 1952 ) 248 . - - 9. - Fed Proc 32: 1862 1869 ( 1973) - . AN ASSESSMENT OF PRIORITIES IN BIOMASS RESEARCH KYOSTI V. SARKANEN PROFESSOR , WOOD CHEMISTRY directed toward optimization of conventional agricultural and orocessing practices of starch producing crons. 3. Rapidly growing hardwoods , such as hybrid poplars and eucalyots are , for many reasons , more advantageous raw materials for the pro duction of cellulose based biomass fuels than either softwood species or agricultural residues , such as corn stover. The improvements made in the growth characteristics of hybrid poplars , which undoubtedly will con tinue , suggests that these varieties will develop to standard agricultural crons with alternative outlets as raw materials for the production of pulp and paper , of solid fuels or of alcohol fuels. It seems, therefore , that hybrid poplars deserve soecific emphasis in biomass conversion research. 4. Recent times have seen impressive oro gress in developing understanding of the complex mechanisms of enzymatic hy olysis of cellulose to glucose , At the same time , the observed complexities of the hydrolysis phenomenon form a hindrance to the evolution of a viable and controllable industrial process. It has become clear that enzymic methods , in general , have serious limitations when applied to solid instead of soluble - - UNIVERSITY OF WASHINGTON COLLEGE OF FOREST RESOURCES , AR 10 SEATTLE , WASHINGTON 98195 - - ABSTRACT Wood and agricultural wastes form a less likely raw material base for biomass fuel industry than agriculturally propogated hybrid poplars. Enzymatic methods of cellulose hydrol ysis and lignin conversions have not fulfilled expectations and consequently , higher research priorities should be assigned to the develop ment of chemical processing technologies, The enigmatic question of lignin utilization in the context of biomass processing deserves expanded research effort. - - - 4 The petroleum crisis in the early seventies gave impetus to research directed toward the development of a special technology for the conversion of biomass materials to liquid fuels and chemicals. Newly evolved methods of microbial gene transfer and enzymatic conversions were envisaged to play a key role in the new biomass technology. In the light of the con siderable body of knowledge acquired during the recent years , it is of interest to critically consider whether the directions that appeared most promising ten years ago should continue to - retain their dominance in biomass research or should be complemented or replaced by alternative approaches. In the presentation , the author will discuss the following propositions for changes in biomass research priorities. 1. It seems unlikely that available biomass waste will form the raw material base for future production of fuels and chemicals , because it is a better feedstock for less discriminating combustion technologies. Consequently , search for high yield agricul tural fuel and chemical crops should be intensified , using photosynthetic productiv ity and suitability for conversion as selec tion criteria. 2. The prediction that cellulose will largely replace starch , sucrose and qluco mannans as industrial sources for glucose remains uncertain. Consequently , increased priority should be given for research - - - - Inti. Symp. Wood & Pulping Chemistry substrates. It is clear that the original expecta tions attached to enzymatic cellulose hydrol - - ysis have not materialized and an industrial application of this process, if it turns out to be successful , lies far in the future. The logical conclusion from this circum stance is that priorities in cellulose hydrolysis research ought to be shifted from enzymatic hydrolysis to the optimization of acid catalyzed hydrolysis technology where the translation of laboratory scale results to industrial practice is more straight forward. 5. Modern technology has its true and unquestioned potential in the fermentation orocesses of soluble carbohydrates. One of the most exciting prospects in this area is the fermentation of pentose sugars to ethanol. The addition of this process to conventional hexose fermentation would sub stantially increase the alcohol fuel yields obtainable from 1 ignocellulosic materials. 6. Enzymatic hydrolysis research has brought to attention the importance of chem ical and mechanical pretreatments prior to hydrolysis. It aopears that oretreatments , preferably combined with delignlfication for - - - - - - 249 the facilitation of recycling of unhydrolyzed cellulose, deserve to be tested also in the context of acid catalyzed hydrolysis. 7. The question about the type of lignin products that may be obtained from ligno cellulosic biomass processing remains enig matic but ought not to be ignored , Additives to phenolic adhesives represent a very limited outlet for biomass lignins, Bio degradation studies , while fundamentally rewarding, have so far revealed little application potential for biomass processing. Alkaline oxidation remains the most effective pathway to low molecular weight lignin products. On the other hand , conversion of lignin, in some manner , to liquid fuel products would ideally complement alcohol fuel production. 8 . In the biomass field , the importance of non utilitarian free scientific inquiry has never been sufficiently recognized , This lack of activity needs to be rectified in order to complement the data base which process technology badly needs for its sound evolution. - - - - 250 - - The theory of Bolker and Brenner [4] pro poses that lignin behaves during acid -sulphite de 1 ignification as if it were composed of stable chains joined by cleavable benzyl -ether cross - THE TOPOCHEMISTRY OF ACID SULPHITE PULPING PART II A THEORETICAL ANALYSIS - - links. R.M. Berry and H.I. Bolker Three parameters define the mathematical expression of the theory: i ) the degree of polymerisation of the preformed chains (y ), ii ) the initial degree of crosslinking ( p * ), and iii ) the rate of crosslink cleavage. It was found previously [1] that a good fit Pulp and Paper Research Institute of Canada 570 St. John's Boulevard Pointe Claire , P.Q • 0 Canada H9R 3J9 We have recently demonstrated [1] how the mathematical theory of degelation , using limited can provide a good fit to the assumptions , experimental data [2] on the topochemistry of the acid sulphite de 1ignification of thin wood - sections. Whiting and Goring [3] have since developed a technique which gives almost com plete separation of middle lamella and secondary wall tissues , and have pulped each tissue sepa rately. The results differ somewhat from the previous data , particularly at high levels of delignification. The difference is shown in Figure 1 , which is a graph of the extent of de 1 igni f icat ion in the middle lamella , (w ) , s ml and secondary wall , ( w ) , plotted against the s s extent of delignification in the whole wood , - - could be obtained to the experimental data by assuming that y was the same in each morphologi cal region , while p ' and the rate were differ - ent. More precisely , it was assumed that the crosslink cleavage was a first order reaction , with its rate determined by crosslink density , but with different rate constants (k , k .) for s ml the reaction in each morphological region. This was expressed mathematically for time , t, by Equation 1 which was rearranged to give Equation and 2 . The values obtained for p /p we re 0.5 and 0.64 respectively . ^^ t . ( IP (Pg/Pg )/ ln (P Solution U. V . 0 T3 0) c o 1 0.2 - -m l ® > k = <7> TJ 111 S iJ . c O O o EO Middle Lamella 0 4 ) = ( 2) /P ks 0 " Secondary Wall ' , sf ( J J T5 5 c l 1.0 0.2 0.4 0.6 0.8 - -E \ 0 o 1.0 0.2 0.4 Middle Lamella 2* 5 « Delignification of wood, weight fraction ( w s ) t Figure 1. ( 1) It has now been found that the best fit to the new data is given by the same scheme but with changed values of P /p and /k ml. New values of 0.64 for p /p and 0.873 for k /k j ^ ^. gave the lowest percentage standard deviation The excellent match between the experimental data and the theoretical scheme is shown in Figure 2. 0.6 E i 08 ££ ln (pml /pml ) k ml , ^^ ^ ^^ ^ ws f ) O U. V . M i c r o s c o p e ln (Ps/p )" 8 = ks o Comparison of the topochemical effect measured on isolated tissue fractions [3] and in situ by U.V. microscopy [2]. preliminary calculations suggested analysis of the new data might permit a simplification of the previous assumptions con cerning the structure and reactivity of lignin , a detailed investigation was undertaken. J 0.6 !^Is" O U Secondary Wall -^ 0.8 < to P -^ ££ i O I 1.0 0 that Inti. Symp. Wood & Pulping Chemistry 0.4 0.6 0.8 1.0 Delignification of wood, weight fraction ( W 5 ) t Since - 0.2 Figure 2 experimental points fit the theoretical curves when Pg/p i = 0.64 and k /k ,nj = 0.873 (data from Refer ence j). The ^ - 251 These calculations brought the best value for the ratio of k to k . rather close to a s ml value of 1. If the ratio i6 given the value of 1 , then a considerably more exacting theoretical scheme is introduced in which the rate constants for the crosslink cleavage ractions ( , k ) kf are assumed to be the same in each morphological region. The result from the analysis of this ^ new scheme is illustrated in Figure 3. Although the standard deviation is higher than in the best fit, the match between experiment and theory is good considering the very restrictive assumptions being made This result contrasts with the analysis of the older data which were very poorly described when ks was made equal to k ’ The new scheme predicts that the ratio ml of benzyl ether crosslinks in the secondary wall and middie lav.ella, is about 0.75. . - 0 c 2 5 .5 °E ? 2 ~ 0.2 __ 5 Ifl c ow E 5) XJ o> o £ o " =- E O C TT . Q C 5° E $ Middle Lamella 0.6 O \o\ 1.0 0 0.2 0.4 0.6 0.8 1.0 Delignif ication of wood, weight fraction ( Ws ) { The fit to experimental points given l /p 1 0.764 3) a" Vo>L;„.„cned °- - If Whiting and Goring [3] are correct in saying that their new results are indeed more accurate , rather than simply different , then the new analysis suggests that the topochemical effect exhibited in acid sulphite pulping is solely dependent on the degrees of crosslinking in the two regions and that the presence or absence of any other wood component does not affect the course of delignification in either the secondary wall or the middle lamella as long as the wood has been saturated with liquor before cooking. An alternative hypothesis , how % - fractions ever , is that the isolation of tissue from the wood matrix removes the physical bar riers contributing to the topochemical effect , thuB leaving only chemical factors to affect the - . If this hypothesis is valid , then the original data constituted a better description 252 i # i The analysis in this paper strengthens ’ evidence for the validity of two concepts , f * First , it reinforces the concept that lignin ) * a gel and that degradation of a gel explain * many phenomena exhibited during pulping , Ih acid sulphite pulping , the fixing of only three i parameters , ( y = 18 , pml = 0.338 , and p * • 0.258), and the application of a very specifA ir form of ge 1 degradation theory permits the description of: ( 1) the relationship between weight average degree of polymerisation and extent of delignification ? (2) the relati onship between degree of crosslinking and extent of delignification ; and finally (3) the topochemi cal effect. Second , the analysis supports the concept that the topochemical effect is largely if not wholly dependent on lignin chemistry during acid sulphite pulping. This conclusion can probably be extended to include the topochemical effect observed in kraft pulping. The latter would be even less likely than acid sulphite pulping to show interference from the wood hemicelluloses ! * - - - - - which are cited [6] as affecting the pore size and hence the rate of diffusion of soluble mate - - 0.8 22 system *I the Pulpi ng rial from the fibre because hemicelluloses are rapidly removed during kraft pulping [5]. The Secondar y Wall LL £: Figure 3. during - 0.4 w . o E of what was occurring intact wood . difference , then , between the magnitudes of the topochemical effects observed in kraft and acid sulphite pulping has to be described in terms of differences in chemistry. Even the topochemical effect observed during acid chlorite delignification can largely be described in terms of chemistry. The results - presented by Whiting and Goring [3] show there is a sudden increase in the topochemical effect halfway through an acid chlorlte cook. This was - explained by invoking a surge in secondary wall delignification due to a sudden removal of hemi cellulose from the secondary wall , The results of Table I from Reference 3, however , show that the rate of removal of lignin from the secondary wall remains constant. Delignification of the middle lamella , on the other hand , almost ceases after 50% lignin removal , This is not what one would expect if hemice 1 lulose were causing the topochemical effect because hemicellulose con centration is highest in the secondary wall . - - The result obtained is rather what would be ex pected if the middle lamella lignin were less reactive and less tractable than the secondary wall lignin. The topochemistry of acid chlorite deligni - fication may therefore be better accounted for considering the differing phenolic content and crosslinking densities of the middle lamella and secondary wall lignins, differences that have been demonstrated by experimental results by r [7] and theoretical analysis [1]. REFERENCES Berry , R.M. and Bolker, H.I • # Chem. Symp., p. 137 ( 1982) 2. Procter , A.R., Yean , W.Q. and Goring , D.A.I., Pulp Paper Mag. Can., 68, T 445 ( 1967). 3. Whiting , P. and Goring , D.A.I • # Wood Chem. Technol • 1 , 111 ( 1981 ). H.S• i 4. Bolker , H.I. and 170, 173 ( 1970). 5. Wood , J. R ., Ahlgren , P.A. and Goring , D.A.I • t Svensk Papperstidn, 75 , 15 ( 1972). ( 6. 1 \ - $ » 1 Ca n. Wood 1. 7. Brenner , Kerr, A.J. and Goring , Chem •• 53, 952 (1975). D.A.I •• Science, Can. J. Yang , J.M. and Goring D.A.I• 9 Trans. Tech. Sect • 9 CPPA, 4, TR2 ( 1978). ) i i i i i 253 peroxide , as well as factors which influence this reaction. HYDROGEN PEROXIDE DECOMPOSITION BY METAL CATALYSTS: BAD ACTORb IN A BLEACHING STAGE J. Thomas Burton and Lori L. Campbell C I L Inc. Chemicals Research Laboratory 2101 Hadwen Road , Sheridan Park Mississauga , Ontario L5 K 2 L3 RESULTS AND DISCUSSION -- A) Studies In the Absence Of Pulp i) ABSTRACT The decomposition of hydrogen peroxide by first row transition metal catalysts has been examined. The reaction rates are pH dependent , increasing with increased alkalinity. For chromium there exists a pH region ( 4 < pH <6 ) in rfhich the decomposition rate is greatly en hanced. A series of stabilizing agents was studied and all were found to be effective against decomposition by manganese. However , rfith iron and copper , catalytic enhancement was observed. Oxygen evolution measurements during peroxide bleaching of meta 1 impregnated pulps •/ere used to determine peroxide lost to decom position processes. Results of this aspect of the study give support to the theory that some peroxide is consumed by " nonbleaching " reactions •/ ith pulp. - - - rhe bleaching of mechanical pulp with hydrogen peroxide has long been regarded as an overall compromise between three reaction types: those /hich lead to either bleaching or darkening of the pulp and those which lead to decomposition cf the peroxide. Yet , there have been few studies which have attempted to distinguish between these reactions. Methods are continually sought which will favour the bleaching reactions over all others. The use of sodium silicate as a bleach liquor stabilizer , for instance , was found early in the development of peroxide bleaching to result in considerable improvements in the bleaching response of mechanical pulps ( 1 , 2 ). Later , the adoption of organic chelating compounds , as Pretreatment a g e n t s , brought about further Improvements attributed to diminished peroxide decomposition through removal of metal c* talysts ( 3 ). This paper describes results from our studies * Rto the catalytic decomposition of hydrogen “ . Symp. Wood The decomposition of hydrogen peroxide by catalysts has been studied extensively by many researchers ( 4 ). The importance of understanding this decomposition is high lighted by the deleterious effect that " bad actors" , such as Mn , Cu and Fe ( present in catalytic quantities in the incoming wood supply and mill white water systems), have on peroxide pulp bleaching. - - The results of our study ( Figure 1 ) show that pH has a pronounced effect on re act ivity. The speciation ( metal com plexes , oxidation states , form of per - oxide , etc.) is enormously complex and precludes a detailed mechanistic study. However, all the catalysis observed can be accounted for qualitatively by either the existence of intermediate inorganic peroxides or the occurrence of conditions ( ie. pH , oxidation potential , precipitate INTRODUCTION t tl Peroxide Decomposition i, Pulping Chemistry formation ) suitable for oxidation - reduction reactions. The metals which fall into the latter category are Mn( II ), Fe( II ), Co( II ), Ni( II ), whereas the marked acceleration in reaction rate seen for Cr( III ) in the region 4 < pH <6 may be attributed to peroxygen complexes which have been proposed ( 5 ) to form under similar condit ions. The results show that in the pH region of interest in peroxide bleaching , 9< pH < ll most transition metals studied are active towards peroxide decomposition and , therefore , must be controlled to achieve maximum bleaching efficiency , As seen by these results , cobalt and manganese are the most effective decomposition agents in this region , although manganese is far more important in pulp bleaching. ii ) Hydrogen Peroxide Stabilization Diethylenet riaminepentaacetic acid ( DTPA ), 255 - dieth ylene t riami nepen ta monop hosph onic Perox ide bleac hing exper iment s acid ( DTMPA ), and sodiu m silic ate were exami ned for their effec tiven ess in were carri ed out on each of these sampl es unde ident ical condi tions ( 2 % H2 0 > , 2% haOH r 4 consi stenc y , 50°C ), but varyi ng leve ls of addit ive ( silic ate , Epsom salt , DTPA or DTMPA ). Oxyge n evolu tion durin g the preve nting the decom posit ion of hydro gen perox ide by Mn( II ), Fe( II ) and Cu( II ). Figur e 2 illus trate s the resul ts in the prese nce of 2.5 ppm Mn( II ). All the t bleac hing stage was monit ored gasi addit ives exami ned had a stabi lizin g actio n with the follo wing order of - metri cally and the volum e conve rted to give the amoun t of H202 decom posed. effec tiven ess 2 silic ate < DTPA * DTMPA Howev er , at 10 ppm manga nese( 11 ) ( Figur e 3) DTMPA is super ior to the other s , In the case of iron at 50 ppm all the addi tives had a catal ytic effec t on the decom posit ion ( Figur e 4 ) , where as for coppe r at 10 ppm ( Figur e 5) addit ion of silic ate and DTMPA prove d to be simil ar in their stabi lizin g abili ty. - It is postu lated that rathe r than stabi lizin g the perox ide, inter media te speci es are forme d betwe en the addit ives and iron which are bette r catal ysts than the metal salt itsel f. Simil ar react ions likel y occur betwe en silic ate and coppe r. This same unexp ected catal ytic actio n has been seen befor e in a study on the decom posit ion of hydro gen perox ide by iron in the prese nce of DTPA (6). - B ) Perox ide Pulp Bleac hing Studi es A groun dwood pulp sampl e was demin erali zed by multi ple chela tion appli catio ns. The pulp was then treat ed with 100 ppm of eithe r manga nese 11 ), ! iron( III ) or coppe r( II) sulph ate. Table 1 indic ates the metal conte nts of these pulps. Figur es 6, 7 and 8 illus trate the relat ionsh ips which exist s betwe en brigh t ness gain and perox ide resid ual , peroxi de consu med by the pulp and perox ide deco m posed , respe ctive ly. In these three figur es the curve s tend to conve rge towar ds the " metal free" resul ts. The surpr ising resul t is Figur e 7 which - - - indic ates that less brigh tness is obta ined when more perox ide react s with the pulp . This, combi ned with the resul ts in Figur e 8 sugge sts that some react ions of hydro gen perox ide with the pulp cons ume perox ide , yet , do not provi de colou r reduc tion. Figur e 9 illus trate s this same data but in terms of a bleac hinq ef f icien cy facto r: Br. Gain % H 202 consu med. As more perox ide decom poses there is a reduc tion in bleac hing effic iency , due in part to the loss of perox ide avail able for bleac hing but also due to other react ion pathw ays At least two inter preta tions are possi ble: eithe r the decom posit ion of hydro gen perox ide caus es darke ning of the pulp which is count er . - - acted by bleac hing react ions which consu me more perox ide or metal catal ysed react ions with the pulp which consu me perox ide and cause forma tion of chrom o - - TABLE 1 phore s resul ting in a reduc ed final brigh tness Furth er study is neces sary . Analy ses of Pulp Sampl es Brigh t Pulp Type Mn( ppm ) Fe( ppm ) Cu( ppm ) ness Origi nal 62.8 0.6 Extra cted -- Mn treat ed Fe t reate d Cu treat ed - 256 86.6 l.l 1.0 17.8 27.6 39.7 142.1 52.9 1.3 0.7 1.2 1.2 85 2 . 64.9 65.2 65.3 62.4 64. R - in order to disti nguis h betwe en these possi bi 1 ities. SUMMA RY: The resul ts of this study empha size the impor tance of prope r manage ment of metal s in mills curre ntly using hydro gen perox ide. Sever al other findi ngs can be highl ighte d: 1. ler Cobalt and manganese were the most effective of the peroxide decomposition catalysts studied above pH7. 2D 4% 2. z ~ 15 <7 - cn Chromium was the only catalyst found to decompose peroxide efficiently under in 3. u —' UJ X oo 0 acidic conditions. - » Chelating agents do not necessarily improve peroxide stability with all 2 5 ppm Mandanese( II ) : , x With Various Additi vesi A? ? ? ° - No Additives o DTPA A - DTMPA - Silicate 257 o 100 UJ Q LO O (J) 100 UJ 80 CL 2: o U 60 UJ o 80 CL : 2 o u 60 UJ Q o y 40 a UJ x 9 CL 20 UJ CL J/ 40 D / • / x 20 - / 9 CL UJ CL 0 1500 2000 2500 Q 3000 — 500 $ 0.1 1006 TIME (SECONDS) Figure 3 , Decomposition Of Hydrogen Peroxide Ficrure 5. With Various Additives: - Q OA- 100 z u 60 LD CL 2 O x < UJ in in a UJ 40 z I o X 20 9 CL CL UJ CL No Additives DTPA DTMPA - Silicate o 80 UJ Decomposition Of Hydrogen Peroxide 10~ 3 M ) By 10 ppm Copper(Il ) With Various Additives: No Additives DTPA DTMPA Silicate UJ in Q !5)o 2500 ( 4.0 x * A- uO 2666 TIME (SECONDS) ( 4.0 x 10 "2 M ) By 10 ppm Manganese(11) o- 1566 CD 00 1000 1500 2000 2500 TIME (SECONDS) Figure 4. _ Decomposition Of Hydrogen Peroxide (4.0 x 10 ,M ) By 50 ppm Iron( II ) With Various Additives: % PEROXIDE RESIDUAL Ficrure 6. - o- DTPA DTMPA 258 -- Silicate J Brightness Gain As A Function Of Peroxide Residual For Bleaching Of Groundwood Impregnated With: No Additives A 100 80 3000 * Manganese Iron Copper Metal Free 8 2 < a 6 on in UJ z 4 x 2 ~ a. CD D0 20 40 60 80 100 X PEROXIDE CONSUMED BY PULP Figure 7. % PEROXIDE DECOMPOSED Brightness Gain As A Function Of Peroxide Consumed By Pulp For Bleaching Of Groundwood Impregnated With: Figure 9. Bleaching Efficiency As A Function Of Peroxide Decomposition For Bleaching Of Groundwood Impregnated With: Manganese Iron Copper Metal Free Manganese Iron Copper Metal Free Bleaching Efficiency = Brightness Gain % Peroxide Consumed By Pulp 8 z LD 6 in in UJ z 4 X - o: 2 CD 00 20 40 60 80 100 X PEROXIDE DECOMPOSED Figure 8. Briahtness Gain As A Function Of Peroxide Decomposed For Bleaching Of Groundwood Impregnated With: A Manganese Iron Copper Metal Free 259 I I I PHOTOACOUSTIC INFRARED SPECTROSCOPIC STUDY OF MECHANICAL PULP BRIGHTENING 0.32 F.G.T. ST GERMAIN and D.G. GRAY - 0) o PULP AND PAPER RESEARCH INSTITUTE OF CANADA , AND DEPARTMENT OF CHEMISTRY, McGILL UNIVERSITY, 3420 UNIVERSITY STREET , MONTREAL, QUEBEC H 3A 2 A7 - In this study , photoacoustic Fourier trans form infrared spectroscopy (FTIR PAS) was used to try and detect chemical changes occurring during the brightening of refiner mechanical pulp ( RMP) from black spruce wood. The photoacoustic technique is an indirect method of obtaining infrared spectra , The ab sorption of modulated infrared radiation by the sample gives rise to sound waves which are de tected and , then, processed to yield an infrared spect rum. The similarity between photoacoustic and conventional infrared spectra is shown in Figures 1 and 2. - c o n 0.24 - O v) n < 0 16 M - 0.08 4000 3200 2400 Wavenumbers 1600 800 / cm 1 ' - Figure 2. - - Conventional FT IR spectrum of black spruce RMP, pressed in a KBr pellet, and not baseline corrected. - photoacoustic signal seen on the spectra is a unitless quantity , which represents the ratio of the signal generated by the sample to that gene rated by carbon black , A value of l (100% ab sorbance ) is arbitrarily assigned to the carbon black. In general , the baseline value was slightly greater than zero, due to ambient noise and cell window absorption. The signal intensi ty was corrected by subtracting this value, as measured around 3900 cm"1. This relied on the - - 0 52 o c S? ty 0 39 - 0 26 - - o (/) 3 O assumption that the baseline value was constant o o Q o .c CL 0 13 - vA 4000 3200 2400 Wavenumbers Figure 1. - 1600 800 - / cm 1 ' Photoacoustic FT- IR spectrum of black spruce RMP. Signal was corrected as outlined in the text. As can be seen, the same peaks appear in both spectra , although their relative intensities do vary . - This is due to the fact that the photo acoustic signal intensity , which is governed by several variables , is inversely proportional to the frequency ( or wavenumber) of the infrared radiation , which explains why the photoacoustic 8ignal is more intense in the low wavenumber re 9ion than in the high wavenumber one , when com pared to the conventional infrared absorption ® Pectrum. In the present work all spectra were ratioed l a carbon black reference. As a resu 1 t , the - - ° 1 ntl * . SymP - throughout the spectral range. The validity of this assumption was suggested by the absence of strongly sloping baseline features that are ty pical of measurements made using KBr pellets. Flat FTIR PAS baselines were also observed in this laboratory for samples other than pulps. Photoacoustic spectra of good quality can he measured directly on pulp and paper sheets , with no special sample oreparation. However, there is some advantage in grinding the pulp samples to a fine powder by means of a Wiley mill (60 mesh screen ), since the smaller particle size causes a significant increase in the signal to noise ratio. The absolute intensities were not very reproducible, but if spectra of two samples of the same pulp were compared , all the peaks Wood & Pulping Chemistry - - - - showed the same relative variation , within expe rimental error (estimated at about 7% relative uncertainty or better ). Peroxide briqhtening experiments were per formed on unextracted RMP , acetone-extracted RMP, and RMP that had been sequentially acetone - - and water extracted , and also on this latter pulp after treatment with sodium hydroxide, All pulps had been treated with EDTA and washed p n - 261 or to brightening, - It was difficult to inter pret the changes in the infrared spectra of the non extracted RMP because a significant amount of extractives was dissolved in the brightening liquor. Each series of brightening experiments was carried out using six liquors with different compositions: 1 ) normal peroxide liquor (hydro gen peroxide , sodium hydroxide , sodium silicate, magnesium sulfate); 2) peroxide liquor without sodium silicate; 3 ) sodium hydroxide, sodium si licate, and magnesium sulfate; 4 ) sodium hydrox ide, magnesium sulfate; 5 ) magnesium sulfate; 6 ) - - - water only. In the case of pulps that had not been trea ted with sodium hydroxide , the most noticeable change in the infrared spectra was a decrease in the intensity of the 1735 cm"1 peak coupled with a smaller increase in the intensity of the 1605 cm- 1 peak upon treatment with any of the li quors, except 5 ) and 6 ). This was best rationa - lized as a hydrolysis of unconjugated esters ( peak at 1735 cm ), possibly present in the he micellulose , resulting in the formation of car boxylate groups ( peak at 1605 cm 1 ). The ”1 ” change in the peak at 1735 cm"1 did not appear related to the brightness gain , since it was essent ially the same between liquors 1 ) through 4 ), while liquors 1) and 2 ) gave a brightness gain of ap proximately 15 points , and liquors 3 ) and 4) caused a brightness loss of 3 points , The change in the peak at 1605 cm” 1 due to the for mation of carboxylate groups is a problem since it may mask changes in intensity due to an aro matic ring stretching vibration which occurs in the same region. This vibration is sensit ive to the presence of a carbonyl groups, which are chromophores of interest in the study of mecha nical pulp. - - - - - In the case of pulp that had been previously treated with sodium hydroxide (at the same con centration and temperature, but for a longer re - - action time than the usual brightening treat ment ), the results were much clearer, Althou gh some ester groups were still hydrolyzed , the magnitude of the change in the intens ity of the peak at 1735 cm” 1 was much smaller and , as a re sult , it was expected that the change in the 1605 cm” 1 peak due solely to the presence of al kali would be small . Treatment with liquor s 3) or 4 ) caused no significant change in the inten sity of the 1605 cm” 1 peak . However , when pe 262 . * -i * peak intensity with a very slight increase of the 1605 cm" 1 peak , which would seem to indic - -! A 3 noticeable decrease was observed in the intens i- i ty of the 1647 cm 1 peak. i ” Borane (BH ») in tetrahydrofuran (TOP) was al so used for brightening , and gave a slighly bet ter brightness gain ( 16 points) than peroxide. - I - \ The effect on the spectra was a noticeable de crease by about the same amount of the peaks at ' 1735, 1647, and 1605 cm 1. The use of a non - - aqueous medium (THF ) precluded the formation of carboxylate groups and , thus , made the decrease in the 1605 cm 1 peak , attributed to a decrease in a carbonyl content , more obvious. Since bo rane attacks ethylenic double bonds , it is pos sible that some of the decrease observed at 1647 ” - - - - cm 1 may be due to the reduction of double bonds on the lignin side chain which could result in a - break in the conjugation and, as a result , a greater brightness gain. Brightening in slightly acidic medium was carried out with sodium dithionite. Mo noticea ble change in the 1735 cm” 1 ester peak was de tected, as expected. A slight decrease in the - - intensity of the 1647 cm” 1 peak was found and a - This decrease f ate • that there is a decrease in a carbonyl content that completely offsets the effect on the spec tra of the increase in carboxylate conten . t sistent with the lower brightness gain achieved with dithionite. - at !605 cm” 1 was observed change , although small , may indicate a - - roxide was used ( liquors 1 ) and 2 )), the change in the intensity of the 1 735 cm" 1 peak was roughly the same os that observed with liquors 3 ) a n d 4 ). but a decrease in the intensity of peak content , A more noticeable de I crease was observed for the 1647 cm” 1 Peak. Conjugated carbonyls, some quinonoid structures and ethylenic double bonds are known to abso rb in the latter region. It is interesting to note that the decrease in the 1647 and 1605 cm” 1 Peak intensities was slightly lower when no silicate was used in the liquor ( liquor 2 )), corres pond ing to a slightly lower brightness. Brightening with sodium borohydride gave the same brightness gain ( 15 points) as peroxide .* However , the decomposition of the borohydride made the medium alkaline , resulting in the hy drolysis of the unconjugated ester bonds. The spectra showed a large decrease in the 1735 cm” 1 smaller decrease was observed for the 1605 cm” 1 peak. The fact that these changes were smaller than in pulps brightened with peroxide was con - the - in a carbonyl - ACKNOWLEDGEMENTS F.St G. wishes to thank the Natural Sciences and Engineering Research Council of Canada for a - postgraduate scholarship. Thanks are due to Messrs. E. Read and J Oagg , and Dr. P. Whitinq , from the ABITIHI Price Research Center in Mis sissauga , for their assistance in preoaring the refiner mechanical pulp. . - - | . Initial chemical composition for both Table I . bagasses BAGASSE DELIGNIFIGATION : CHEMICAL COMPONENTS RELATIONS PROPERTIE Cellulose Hemicellulo3e9 Nancy Fernandez Juan Sabatier Lignin Natasha Romero Rolando Cruz Raymundo Guadarrama Gretel Mieres Research Division , Cuba 9 Project UNIT COIII'ERCIAL LO.V HET’ICELL. ° 47,5 62,5 fo 25.7 20.8 9,0 24,8 / % RESULTS AND DISCUSSION Hydroxyl ions concentration (OH , mol/L), re cidual lignin (#) and yield (/) deeply decrease during the earliest moments of alkaline pulpinc, as is shovm for lignin in Fig 1 - - - - — Sugar Cane By Products Cuban Research Institute .. - P.C. Box 4026, Havana , Cuba ABSTRACT Morphological and chemical characteristics of bagasse led to search short time and high effici ency delignification processes Bagasse delignifi cation is a very fast reaction, and it is possible to produce pulps of different qualities ranging from chemimechanical up to chemical pulps in shorter times than the usual commercial ones and obtaining higher yield and strength properties just selecting adequate chemical and temperature conditions. - . - - . 1. Residual lignin vs time for both bagasses. Pulping conditions: 16 initial Na , 100 C. 20 ° Fig KEYWORDS: Bagasse, Delignification, Chemical ^ Composition INTRl DUCTION nification rate of wood hemicelluloses are removed from the cellular wall, Goring and Kerr (1 ) established than the delig is higher when - increa sing in this way the average pore 3 ize and making . diffusion of lignin degradation products easier .asura (2) indicates the exis In another paper, I' tence of three phases in wood delignification, but only in the second one the greatest lignin removal is produced. The results of Fernandez (3) and others show that b gnsse lignin is more reactive and accesible than wood lignin. The object of this paper is to describe the results we have obtained searching shorter and more efficient delignification proce sses for bagasse - - - . S y m p. Wood k P u l p i n g C h e m i s t r y - - - - *ers. . - jjATKRIALS AND METHODS Experiments were carried out using a commercial depithed bagasse and another with low hemicellulo Bes content For both bagasses the trials were first achieved on stainless steel microdigesters of 000 ml, capacity , and the results were checked Afterwards on 15 L and 18 L stainless steel digec . - It i3 evident the existence of an "uneasily re movable lignin" for both bagnsses Taking a fur ther look to Fig. 2, it is also clear that this "uneasily removable lignin" cl creases when there are favorable conditions for diffusion and/or stronger pulping conditions (higher temperature and/or initial alkali concentration). . 2. Residual lignin vs time for commercial Fig . bagasse at different pulping conditions a - 16 % initial Na , 165 C . 20 ° b.- 12 1» initial Na20, 165 C ° c.- 12 # initial Ik O, 100 c ° ^ 263 - I t was possibl e to find some mathem atical rela tions betwee n differe nt chemic al p r o p e r t i e s during deligni ficatio n as i s shown i n Fig .3 , * I LEGEND I B < 6 4 PHASE cr f! PHASE n I # COMME RCIAL BAGASS E PHASE I m i l S3 i 4 times A BEECH i I REFER ENCES SPRUCE 1 J 2 80 60 40 YIELD, 0/© Fig ) A 20 Univer sity . 3 Delign if ication phases f o r wood ( 2 ) « and bagasse , . . , accordi ng to what chemic als . and temper ature condit ions must be selecte d In t h i s way , i t i s p o s s i b l e to obtain pulps with good p r o p e r t i e s and a greater y i e l d than the co mmerc ial ones in shorte r times , as i s shown in Table I I . Chemi mech 1 lignin , . 92-96 . 17-20 Breakin g Length km 2.5 3 , 5 • - - “ 3-4 300-400 50-55 55-65 - - Tear 9-11 100- 400 35 40 4 5 t ‘ RAYIO JNDO GUAD ARRA MA GRETE L MIERE S . RESUM E Les caract £ r i s t i q u e s morpho logique s et chuniqu e du bagasse condui te l e s recher ches vers l 1 etude - . des proced ls v i t e s ^ 6 7 niques par un do3age des produit s chimiqu es temp6 rature de cuisoo n a p p r o p i £ s . i t has been pointed out the existen ce of an Bily remova ble l i g n i n in bagasse , " unea " - which decrea ses when favora ble diffus ion and or strong er pulping / condit ions are a p p l i e d . Remov al of hemic ellulo aec i s favora ble f o r d e l i g nif ication and increas es bagasse r e a c t i v i t y , pro bably due to a g r e a t e r pore s i z e of bagasse cellu l a r wall This remova l , as well as higher temper a tures and i n i t i a l a l k a l i concen tration , decrea se the amoun t of " uneasil y remova ble l i g n i n *’ - - . . - ct de haut rendem ent In dam nificat ion c ' est une reacti on t r 6s v i t e , et peut etre produir e des pates A dlffere nts qualit ies depuis chimi-m canique jusqu a quimiqu es , dans ’ temps plus has que l e s utilise s dans 1 * Indust rie , avec des raeilleu rs rendem ents et p r o p i 6r t 6s m6 ca CONC LUSIO NS 264 NANC Y FERNA NDEZ JUAN S BATIE R NATAS HA ROME RO Project Cuba 9 I n s t i t u t Cubain e des Recher ches de l e s D4 r i v 6s de l a Canne a Sucre Chemic al 15 60 64 10 15 100 200 . 80-84 0 10 # Freene ss , CSF , Semich em DELI GN IF IC A TI ON DU BAGA SSE: RELAT IONS ENTRE LES CONS TITUA NS CHIMI QUES -. . Differ ent soda pulping alterna tives Table II Yield , # Residu al " ROLAN DO CRUZ - Time , min . Bratisl ava , Czecho slovaq uin ( 1979 . Contra rily to wood bagasse does not have three deligni ficatio n phases Bagass e deligni ficatio n i s produc ed in the earlies t mome nts of pulping and i t i s not necess ary to increas e cooking time The optimal cooking time depend s on the desired pulp to be rpoduce d A 2 I IOO .- GORING ,J . .1. and KERR , .J . Delign ificati on of wood . Can . J . Chem . 53 : 95 L 959 ( 1975 ) .- MADURA , V • Alkali ne degrad ation-of spruce and beech wood . Wood Sci . Techno l . 16 : 155 164 ( 1982 ) 3.- FERNA NDEZ , IT . Ph .D. Thesis . Slovak Techn ical I O short er . ( HARDW OOD ) ( SOFTWO OD) I - ob tain differe nt pulp qualiti es for bagasse with hi gher yields and lower l i g n i n conten ts in e O) Accord ing to the relatio ns establi shed betw fcen bagasse chemic al compo nents , i t i s now possibl e to choose more adequa te pulping condit ions to - et une * ORGANOSOL V PULPING WITH ACETIC ACID . . Nimz and R. Casten H H Institute of Wood Chemistry and Chemical Technology of Wood , Federal Research Centre for Forestry and Forest Products Leuschnerst rasse 91 , 0 - 2050 Hamburg 80 , Federal Republic of Germany As early as 1916 Pauly has found that lignin can be partly extracted from wood and annual plants by refluxing with aqueous acetic acid in . the presence of mineral acids However , only 72 Z of the lignin could be extracted from spruce wood chips after 30 hours cooking ( Pauly 1934 , . Schutz and Knackstedt 1942 ) We have found that delignificatio n is much more effective and the cooking time can be reduced to 2 - 5 hours when the wood chips or cereal straws are continuously extracted with 95 Z acetic acid, containing 0.1 Z hydrogen chloride at 110°C . At the end of the extraction , 3 - 5 Z hydrogen peroxide ( based on wood ) are added to the 70 Z aqueous acetic acid , instead of hydrogen chloride , and the . mixture is stored for eight hours at 80 ° C The hydrogen peroxide reacts with the acetic acid in forming peroxyacetic acid , which is a powerful , selective bleaching agent . In the case of beech wood chips , a kappa number of 7 is obtained after four hours extraction Additiona 1 bleaching leads to a brightness de gree of 85 Z ISO at a pulp yield of some 40 % DP values are above 2000 . . and can be improved significantly by extraction with alkali , indicating that some hemicellulos es are left in the pulp after the extraction and bleaching steps . Breaking lengths are between 8 and 12 km and a -cellu- lose contents above 90 % being further improved by extraction with alkali . Kappa numbers below 30 at pulp yields of 47 % are obtained from spruce wood chips after extraction with acetic acid for four hours Subse . - quent bleaching with hydrogen peroxide leads to brightness degrees of up to 70 Z Breaking length is around 10 km, burst index 35 m2 and . . Pine wood needs the highest and cereal straw the lowest . Both lead to pulps with acceptable strength properties and brightness degree . The extracts are evaporated in vacuum and the residual s i r u p s are poured into water . Thereafter , the DP 2.200 amounts of acetic acid precipitated lignin can easily be filtered off , while the hemicellulos es are obtained in the filtrate They may be separated from low molecular . weight phenols as well as from acetic acid by extraction with methylene chloride . In this way , three fractions are obtained, consisting of lignin , hemicellulos es , and low molecular weight phenols , the latter being only of minor amounts . According to the mild pulping conditions , the lignin is only weakly condensed , thermoplastic and soluble in many organic solvents Its molecular weight is between 2000 and 3000 Daltons I t contains up to 10 Z acetyl groups , but no chlorine The acetyl groups are mainly . - . . linked to the y carbon atoms , while the phenol groups are not esteri - fied and more frequent than in MWL . This makes acetosolv lignin ( ACL ) a convenient material as an adhesive for particle boards Lique . faction - of ACL by hydroqenolys is and gasification by pyrolysis are under research in our laboratory Inti Symp. on Wood and Pulping Chemistry . 265 Likewise , the hemicellulose fraction deserves attention as a chemical feedstock Our present interest focuses on three chemicals , furfural from hardwoods and annual plants and hydroxymethylfurfural from soft wood , as well as acetic acid from both . Due to the high concentration of pentosans and hexosans in the hemicellulose fractions , t h e i r yield . - should be higher than from conventional spent liquors that consist mainly of 1 ignin . If compared with conventional pulping acetosolv pulping offers the following advantages: - The pulping chemicals , acetic and hydrochloric acids , are recovered by distillation - Losses of acetic acid may be compensated by acetyl groups in wood - The evaporation energy of acetic acid is less than one f i f t h from that of water - No pressure vessels are needed - Lignin and hemicelluloses are obtained separately and in a low con densed ,sulfur- free form - No sulfur or chlorine containing effluents are produced - The amount of wash waters i s d r a s t i c a l l y reduced . i * >t o i •W : * r. > f I ! cf * « * * . . It. ' ** * • »• -t i » - f , i % f r. * \ •4 r* • 266 1 3C NMR SPECTRA OF ACETIC ACID LIGNINS H.H. Nimz and D. Robert Institute of Wood Chemistry and Chemical Technology of Wood Federal Research Centre for Forestry and Forest Products Leuschnerstr. 91 , D 2050 Hamburg 80, Federal Republic of Germany , and Laboratoire C.O.P./DRF , Centre d 'Etudes Nucleaires , 85 X F 38041 Grenoble Cedex , France - Carbon- 13 NMR spectroscopy is a meaningful tool for tracing chemical reactions of lignin. In the case of organosolv pulping with aqueous chloroethanol (CE), it can be shown that the solvent forms ether bonds with the a carbon atoms in lignin. The corresponding signal of the a carbon atom is shifted downfield from 73.2 ppm to 81.9 ppm and two additional signals appear at 44.5 and 70.3 ppm that can be assign ed to the carbon atoms in the chloroethyl groups. - - It was found in our laboratory that most of the CE can be replaced by acetic acid. Using 2.5 % CE in 90 % aqueous acetic acid , which is still a powerful pulping mixture, the extracted spruce lignin gives a carbon 13 spectrum lacking the three above mentioned signals in dicative for chloroethyl groups. Instead two other signals appear at 171.3 and 64 ppm that can be assigned to acetylated Y hydroxyl group s. - - Similar spectra are recorded from lignins ( ACLs ) obtained from spruce wood chips by continuous extraction with 95 % aqueous aceti c acid containing 0.1 % hydrogen chloride at 110 C. ° A closer look reveals characteristic differences between spruc e ACL the a hydroxy groups is alsoac ylated. From the relative intensitie s of the signals between 145 and 155 ppm , assigned to carbon atoms 3 and 4, it can be seen that ACL contains more free phenolic hydroxyl groups than MWL , indicating a partial splitting of the 6 0 4 linkages. This is further confirmed by the relative intensities of the signals at around 136 and 133.5 ppm , indicating carbon atom 1 in etherified and phenolic guaiacyl groups , respectively. The most prominent signa ls of ACL between 110 and 136 ppm , at 129 and 115.8 ppm , may be partially assigned to carbon atoms 2/6 and 3/5 in p hydroxyphe nyl residues. From the aliphatic part of the ACL spectrum partial acetylation of the y hydroxyl groups and splitting of the B 0 4 linkages is further confirmed. and MWL. Besides the Y hydroxyl groups , a minor part of - ^ - -- - - -- In the spectrum of beech lignin carbo n atoms 3 and 5 give a signal at 153.9 ppm in etherified and at 148.7 in phenolic syringyl units. Comparison of the relative intensities of these signals in the spectra from beech MWL and ACL reveals that the latter contains more phenolic hydroxyl groups. From the aliphatic part of the ACL and MWL spectra it is obvious that the 6 0 4 ethers in ACL are partially split and the y hydroxyl groups are partially acetylated. Similar results are obtained from the spectra of straw lignins. -- - Inti. Symp. on Wood and Pulping Chemi stry 267 I - HC CT - HO CH INTERPRETATION IN CHEMICAL TERMS OF SOME SELECTIVITY PROBLEMS DURING PULPING AND BLEACHING JOSEF GIERER OAr = liberated ( phenolic ) portion of the lignin molecule DIVISION OF WOOD CHEMISTRY ROYAL INSTITUTE OF TECHNOLOGY S 100 44 STOCKHOLM , SWEDEN HJCOH H 2 COH H 2 COH - OR = liberated portion of the polysaccharide molecule ABSTRACT The most important lignin degradation reactions taking Fig. 2. Alkaline cleavage of B aryl ether bonds in lignin and glycosidic bonds in carbohydrates - place during pulping and bleaching follow mechanisms which apply also to the carbohydrate reactions during these processes. Examples for the analogies between the -‘OAr mechanisms of lignin and carbohydrate reactions are given. These provide an explanation for the limited selectivity of current pulping and bleaching processes with respect OAr * ( iberoted ( phenolic ) to lignin degradation and dissolution. portion of the lignin molecule /3 « HC I I -OR - aC - OH HC * 0R C II I c - o" In this paper an attempt is made to identify the main - OH c =o i i reason for the limited selectivity of pulping and OR = remaining portion bleaching processes currently applied. The most important of the polysaccharide molecule reactions of lignin during pulping and bleaching will be compared with those of the carbohydrate constituents , Fig. 3. Alkaline cleavage of a aryl ether bonds in lignin and B elimination in carbohydrates - - and the parallels existing between the mechanisms of the reactions of these two different substrates will be H 3 CO emphasized. • 0 ^ Examples of fragmentation and condensation reactions CH«0 - of lignins and of corresponding reactions of carbo hydrates , taking place during pulping , will be presented . These include 1 ) Acidic cleavage of aryl ether bonds and glycosidic bonds (Fig. 1) - ii - l I - HOC = 0 glycolic acid CH 20H HOC H HC OH I CH20 H HOC - 0 rv HC — OCell I " H2O HOC CM? 0H i ^ ^-H HC — OCell 2) Alkaline cleavage of aryl ether bonds and glycosidic bonds (Fig. 2) ) 3 Alkali induced cleavage of a aryl ether bonds and 8 elimination during peeling (Fig. 3) 4) Alkali promoted cleavage of carbon carbon bonds in lignins and carbohydrates (Fig. 4) 5) Condensation reactions between lignin fragments (Fig. 5), and between lignin and carbohydrate fragments (Fig. 6 and 7) - CH22 OH I C OH HCOH I 20H CH CH OH 2. 3 - enedioi - HC i — OCell HC OH I CH20H erythntol end group - Fig. 4. Cleavage of C C bonds by alkali - I HC- OR H* H C - OR H* A 1 R a adjacent lignin unit H4 H HC - O- R r 0 i r HC - O- R 0 HC * HC * r 0 ROH ROH I R 3 adjacent carbohydrate unit Fig. 1 . Acidic hydrolysis of benzylaryl ether bonds in lignin and of glycosidic bonds in carbohydrates Inti . Symp. on Wood and Pulping Chemistry fig . 5 » Lignin condensation. Formation of a diary lute structure thane 269 Phenolic units in lignins OH Reducing end groups in polysaccharides - Fig. 6. Formation of a C C bond between lignin and carbohydra tes by conjugate addition CMpOM CH 3 I CH 3 C=0 c=o I I CHO 0 I COH HCOH I HCOH II H .- OH II. CH3CCHOH H20 0“ - Fig. 9. C C cleavage by oxygenati on followed by rearrange ment via dioxetane s - OCH3 ' •H00 tl CH 3 C 0 - COOH I H O- C C H3 - -H 0 * 0 0 CH?0H c= o I \ CH 2 0 CH7OH •H00* 0 * H* 0 V 0 " - — _ — '- o ° 0 0. CHjOH 0 CM?OH 0, 0 0\ io * 0 - Fig. 10. Intramole cular nucleophi lic attack of hydro peroxide intermedi ates - Fig. 7. Formation of a C C bond between lignin and carbohydra tes by aldol condensat ion The parallels between the mechanism s of the bleaching reactions of these two substrate s are less pronounced , due to the partly aromatic nature of lignin. However , if sufficien tly aggressiv e bleaching species or reactive structures are involved , the following analogies may be discerned. 1 ) Hydrogen abstracti on by radicals , HO’, resulting in the introduct ion of carbonyl groups (Fig. 8) 2) Electron abstracti on from phenolic and enolic struc ture6 by oxygen , followed by oxygenati on and fragmenta tion (Fig. 9) 3) Addition of titu * leophi 1 ic species , e.g. HO , H00 or CIO , to dicarbony l structures , followed by fragmentat ion (Fig. 10) - HO * H - 20 HO CH 3OH 0 HjCOH HjCOH HO * \ * H?0 V H?C0H 0 ^ O • HO * - HjO OH 0 0 OH OH M ?C0H Fig. 8. Abstracti on of hydrogen atoms. Introduct ion of carbonyl groups 270 In the light of these mechanis tic analogies between lignin and carbohydra te reactions , the selectivi ty problem encounter ed in current de 1 ignificat ion processes will be briefly discussed . COMPARISON OF PRETREATOENT METHODS FOR ENHANCING THE ENZYMATIC HYDROLYSIS OF WOOD H . H . BROWNELL i ° FORINTEK CANADA CORP. 800 MONTREAL ROAD OTTAWA , ONTARIO KIG 3Z5 - ABSTRACT « i frcm the steam explosion, Process variables such as impregnation with sulfuric acid of 0.2% concentration , which selectively accelerates hydrolysis relative to pyrolysis, improve the solubilization of xylan relative to its destruction, and improve enzymatic hydrolysis. Mass balances, with and without added acid , are compared. High steam tenperatures, such as 240 or 250 C, permit short treatment times but can result in uneven cooking of the chips. Air dry , or partially dried aspenwood chips, even when thicker than 3 rnn , heat rapidly as a result of steam passage into the wood through the vessels and release of the latent heat by condensation inside the chips. Aspenwod chips such as those impregnated with dilute acid , which have moisture contents (MC) greater than 100% (dry basis), become filled with water before reaching steam temperature. Further temperature rise of chip centers is then only effected by relatively slew heat conduction from the outer surface. Large wet chips of thickness greater than 3 mm are therefore unevenly cooked by 250 C steam. Lower temperatures lengthen required cooking time and premoce more even cooking. Moisture content has a major effect on consumption of high pressure steam with green wood (MC 100%) requiring twice as much steam to heat the moisture as to heat the wood substance. When snail chips are used , MC (air dry vs green) has little effect on solubilization of xylan, or on glucose yield on subsequent enzymatic hydrolysis. Different methods of pretreating wood substrates to enhance enzymatic hydrolysis are discussed , and the effects on the recovery of lignin and henucellulose ccnponents are compared. Of the different pretreatment methods, those involving heating with steam appear, at present, to be the most economical. The principal mechanisn of accessibility enhancenent in all steaming processes appears to be the hydrolysis and dissolution of a significant part of the henucellulose, which creates pores large enough to accomodate molecules of cellulase. Explosive decom pression at the end of a steam treatment contributes virtually nothing to subsequent water extraction of xylan and to enzymatic hydrolysis. The products obtained after treatment with 240°C steam for 90 or 180 s, followed by steam explosion frcm the full steam pressure of 3.24 MPa, were compared with those obtained after similar steam treatments followed by bleed dewn of pressure to only 0.69 or 0.34 MPa before explosive release. Similar yields of glucose were obtained on enzymatic hydrolysis, and similar yields of butanediol and of ethanol were obtained on combined hydrolysis and fermentation, regardless of the magnitude of the pressure drop on release. This was true even though the 90 s product was still in chip form after release frcm the bled dcwn pressure. The water soluble fraction, of steam treated chips obtained without explosion, was easily extracted. Two thirds of it was recovered as a 9% solution without concentration. Steam tenperatures above 200 t cause significant pyrolysis of the xylan, with formation of CC>2 (2% after 2 min at 240 C) and smaller amounts of CO, and with a significant decrease in the combined oxygen content of the resulting steam exploded aspenwood (frcm 43.58 to 41.54%). Pyrolysis is undesirable in steam treatment and contributes little or nothing to hemicellulose solubilization and subsequent enzymatic hydrolysis. Pyrolysis for 6.5 min of aspenwood wafers in dry (superheated) steam at 276 C reduced the pentosan content to 66% of its original value an identical reduction to that caused by saturated steam treatment at 240°C for 80 5 follcwed by steam explosion. Hcwever , only 4% of the surviving pentosan fran the pyrolysis was water soluble, compared with 85% of that - ° - - - - - ^ ° - ° Inti. Symp. on Wood and Pulping Chemistry - 271 •' Detection, Prediction, Synthesis and Confirmation of a Mutagen 3 Using the Ames salmonella bioassay , strain TAI 00 , V ** synthesized 3,5,5 - trichloropent - 4 - ene - 2 - one was found to be a direct acting mutagen, as had been predicted. Most Gintautus Strumila, Ian Johnson, Bonnie Isacovics, Howard Rapson direct acting . alkylating agents 4 mutagens Mutagenicity is purine and pyrimidine bases of DNA Department of Chemical Engineering and Applied Chemistry are caused by alkylation of the . During cell replication DNA strands split and the separated strands are used as templates to synthsize new DNA University of Toronto, Canada . The correct sequence of bases the bases of the new and template strands GCMS in the solution resulting from aqueous chlorination of acetovanillone, a model compound typical of some of the structural units of the . softwood lignin molecule contains the substituted guaiacol is .* similar to that produced by the chlorination of kraft pulp The chlorination filtrates were characterized by extraction with ether and analysis - . Fewer products are obtained from of the extracts by GC MS chlorination of acetovanillone than from chlorination of kraft pulp This simplifies the identification of products by GC - MS and . the determination of their degree of mutagenicity change the genetic methane as the chromatogram ( 70 eV ion gas ) reagent - ing properties of the chlorine atom cluster about the M l ion * of the gas indicates that three . The electron chlorine atoms are present in the molecule impact the same peak exhibits a very intense m / e 43 ion . The which indicates that the compound contains an acetyl group these data is C H OCI ^ ^ . From the ^ fragmentation patterns ( figure 3 ) this compound was assigned the . structure 3, 5,5- trichloropent 4 ene 2 - one -- It was observed that - filtrates from the chlorination of unbleached pulp were mutagenic dioxide the of , while filtrates from chlorine same unbleached pulp were not .1 Analysis of the filtrates indicated that chlorine pro- - chlorocarbony ! group contain,ng compounds, such as tetrachloroacetone, while chlorine dioxide did not . Therefore produce such structures . it was predicted from its 3 , 5 , 5 - t r i c h l o r o p e n t - 4 e n e - 2 - o n e would be - The compound was synthesized by the method of Kiehlmann et .2 al similar The product exhibited an identical El mass spectrum and gas chromatograph - chlorine make the carbonyl more suscep 3,5,5 - trichloropent - 4 - ene - 2 - one would be a strong electrophile . in work this is that led it to an retention time to the . identified in the chlorination f i l t r a t e Inti. Symp. on Wood and Pulping C h e m i s t r y compound . molecules which tend to make them direct acting mutagens One such structure is chlorine atoms on a carbon next to a , 1 •t l , * Another mutagenic structure is chlorine atoms . carbonyl group on a carbon of a carbon =carbon double or on a carbon next to . one A systematic study quantitative is in progress of the direct acting mutagenicity of all aliphatic compounds containing from 2 to 5 carbon atoms, chlorine atoms, and either a carbonyl . The ultimate goal group or a double bond, or both to forecast from its the degree of structure is to be able mutagenicity . possessed by any chlorinated aliphatic compound The chlorinated . acetones are now being studied Up to the present , the sum of the mutagenicity of all the many mutagens which have been identified in pulp chlorination filtrates does mutagenicity in duced mutagenic mutagenic the new cell, and hence mutagenic , as found mutagenic structure that in . Olefin and carbonyl groups make chlorine more susceptible to nucleophilic substitution. Thus . The ratio of the isotopic treatment the DNA tible to nucleophilic attack indicating a molecular weight of 186 which fits of Both carbonyl groups and chlorinated hydrocarbons are The importance of chromatographic peak eluting at 18.2 minutes ( Figure 2 ) shows a quasi molecular M 1 ion ( molecule plus a proton) of m / e 187, * formula expression electrophiles. In chloroketones the inductive electron withdraw . electron impact ) of the ether extract of the solution of products of chlorination of acetovanillone. The chemical ionization mass only the hydrogen bonding between bases and can hypothesis concerning the types of chlorine containing structures Figure I is part of the total spectrum of . Alkylation of the cause inclusion of the wrong base in the new strand. This may group . It has been demonstrated that the mutagenicity ( using bases disturbs . produced by aqueous chlorination of acetovanillone spectrum the strands resulting in a mutation lignin present in in being synthesized is determined by hydrogen bonding between In 1980 a compound was detected by Acetovanillone electrophilic strong not account for as much as half of its total . Apparently many mutagens remain to be identified . such solutions References: . Rapson, W. H., Nazar , M. A. and Butsky , V. V.. Bull. Environ. Contain, and Toxicol. 24 , 590 - 596 ( 1980 ). 2. Kiehlmann, E., Loo, P.- W., Meoon, B.C. and McGillivray , N. Can. J. Chem. 49:2964 1971 ). 3. Maron, D.M. and Ames, B.N., Mutation Research, 1 1 3 , 1 7 3 1 ( . ( 1983 ) . Hathaway , D.E. and Kolar , G.F • Chem. Soc . R e v i e w s 4 • . 9 ( 2 ):24 |, ( 1980 ) 273 -- - r r T pT r 1 r A . 1 2. 0 11.0 - rr r r A. - -- - - - -r rprrrp-r-r rp r i r j iTH i J T i —» pr T r r j » T r i pi . 1 5. 0 14 0 13 0 - ML J rr T r ' 1 7. 0 1 6. 0 •pf t . 1 8. 0 19 0 20 Figure 1 Totol ion chromatogram of ether extract of aqueous chlorination filtrate from the aqueous chlorination of ocetovanillone. 151 -BO 2000 1 * 123 1000 " 89 T T I l T 40 00 109 i T 100 | 60 107 1 47 / 0 , 40 125 99 T T T 120 T I 1 40 T T T 180 160 T 200 Figure 2 • # Chemical ionization mass spectrum from chromatogram ( 18.2 min) of the ether extract of the aqueous chlorination of ocetovanillone. i 43 6000 ' :BO 40007 h 20007 40 73 87 83 • s .\ 51 .. —• •/ o I i i T 40 123 100 1 r< r 60 - T l f t I / i TT T 80 T ltd r T 1 43 .. T i• r 1 00 t 125 120 151 / 153 / • i T T 1 40 160 —r ’'T T ' 180 -iT) I'n 200 Figure 3 t *# Electron impact mass spectrum from chromatogram ( 18.2 min) of the ether extract of the aqueous chlorination of ocetovanillone . 43 12000 ^ "BO Cl Cl 8 0 0 0" 40 07 40007 oJ^r 40 i \. 1.1 rr 1 43 108 iL * 151 / / l i t! r t| r - -. - — . l. - i * pr r r 1 40 100 Figure 4 - — i. . r rr T r pt » » | 160 — Electron impact moss soectum of 3,5,5 trichloropent 4 - en - 2 one 274 1 8%6 N T V 100 ] p » I T )1 200 i To be able to control this process from the kinetical - point of view, an understanding of the sulphonation reac tions at very short times is necessary. For this purpose cooking equipment was especially designed to permit the THE KINETICS OF SULPHONATION REACTIONS ON NORWEGIAN SPRUCE* study of reaction times as short as 15 seconds under - PER ENCSTRAND , LARS AKE HAMMAR and MYAT HTUN . pressurized conditions SWEDISH FOR£ST PRODUCTS RESEARCH LABORATORY BOX 5604 S 114 86 STOCKHOLM , SWEDEN EXPERIMENTAL — Preparation of wood meal Fresh logs of Norwegian spruce (Picea abies) from the neighbourhood of Stockholm were debarked and the sapwood . After chipping by hand , ABSTRACT was separated from the heartwood This study describes the kinetics of sulphonation at short reaction times (15 seconds to the chips were disintegrated to wood meal in a Wiley mill 15 minutes). The to a size that passed a 40 mesh screen. The wood kinetics were studied at different temperatures , different sodium sulphite concentrations and different pH levels on neal was stored dry at 4°C. In this study wood meal from sapwood onlv has been used. wood meal in a specially designed reactor. - The results show that under normal conditions (2 4 Z - - - Na SO j charge , pH 8 11), about 7 5 Z of the sulphona ^ Preparation of cooking chemicals The sulphite liquor was prepared from solid sodium tion achieved within 15 minutes has already taken place - were adjusted with sodium hydroxide. The pH value and sul phite concentration were measured before and after each > i - As expected , an increase in temperature and an in crease in sodium sulphite concentration give a higher in - itial reaction rate. - cooking trial. The pH measurements were carried out at room temperature. Cooking liquors with pH 8.0, 9.5 and - 11.0 have been used the sulphite concentrations of 0.02 , The mechanism of the influence of pH at different temperatures and at - disulphite of analytical grade and the different pH levels . within 1 minute different sodium sulphite concentra - tions in the alkaline region is at present not clear. - 0.08 and 0.16 mol /1 a each pH level. Cooking equipment - The cooking equipment used in these trials is design KEYWORDS: Sulphonation, kinetics, cheraimechanica 1 .. pulping. ed in order to permit the study of the sulphonation reac - tlons of wood at a period between 15 seconds and 15 min # utes, In accordance with the sulphonation time applied in f INTRODUCTION a CTMP manufacturing process. Important pulp and paper properties such as shives The scheme of the reactor (cooking equipment) is out content , particle size distribution , handsheet tensile - strength , dewatering capacity and resin content can be pressurized vessel with a stirring device attached to It. The cooking liquor is placed in the vessel and is heated partly attributed to the degree of sulphonation of CTMP - . Commercial CTMP mills now in operation in Sweden ( 1 S) and other countries use low sulphite charges in the alka - line area and short preheating time. CTMP is in this paper defined as a pulp with a yield of about 95 per cent. This type of CTMP is mostly used in products such as carton board , fluff , tissue and to some extent in different . printing grades Many studies on the sulphonation of wood have been - reported earlier (6 10), but most of these works are devoted to the neutral and acidic regions. In addition , they evaluate only the longer reaction time region , i.e. from about 10 minutes to 3 days. Tills means that the Information from these studies are not adequate for the control and optimization of the CTMP process now indust rla 1 ly used • - lined in Figure 1. The reactor consists of a double walled by ethylene glycol circulated between the two walls of the vessel. 30 g of wood meal is mixed with 200 ml deionized water and placed in the Inner cylinder the upper erxi which is connected to a tube pressurized with nitrogen gas. The wood meal suspension is shot into the preheated cooking liquor by opening the lower valve of the tube. Samples are extracted at various times by opening the valve at the bottom of the reactor. The sulphonation reaction In the sample was slowed down by collecting It In . a bucket filled with ice prepared from deionized water Determination of sulphur content The sulphonated samples were thoroughly washed with deionized water by means of a displacement washer for a - period of 12 hours at room temperature. The amount of sul phur bonded to the wood was then measured bv tlie Schoniger method and Ion chromatography ( 11 ). - * Conditions corresponding to the CTMP processes in Scandinavia. Inti . Symp. on Wood and Pulpiruj Chemistry 275 I n f i g u r e 3, t h e s u l p h u r c o n t e n t i s p l o t t e d a g a i n s t N 2 ~ overpressure the logarithm of time \ . The results show that the reaction i s n o t t e r m i n a t e d a t I S m i n u t e s ( t h o u g h f r o m a CTMP process point of view the sulphonation i s very slow) hut Tube with woodmeal susp. follows an exponential law within the time interval Stirring . measured Sulphur content , mmol / kg wood Heating with ethylene glycol 100 Reactor with cooking liquor <.3 50 P0.5 Thermocouple 1 10 3 30 60 Time, min i Sampling . D e g r e e o f s u l p h o n a t i o n a s a f u n c t ioof n 0 of. 0 8 l o g Figure 3 Figure l time at a sulphite concentration m o l e s / 1 , pH 9 . 5 a n d a t e m p e r a t u r e o f 1 3 0 ^ C . Reaction vessel designed for sulphonation . studies during short reaction times under p r e s s u r i z e d c o n d i t i o n s. Effect of temperature The effect of ° t e m p e r a t u r e ( 7 0 a n d 1 3 0 C) o n t h e degree of sulphonation i s shown in figure 4 RESULTS AND D I S C U S S I O N . The degree of s u l p h o n a t i o n i6 i n c r e a s e d t w o f o l d w h e n t h e s u l p h o n a t I o n °. i s a l l o w e d t o t a k e p l a c e a t 1 3 0°C i n s t e a d o f a t 7 0 C Sulphonation kinetics A typical relationship between the degree of sul - It is obvious that the reaction within the time range phonation ( sulphur content ) versus time i s shown i n studied is thermally activated in accordance with the - f i g u r e 2 f o r s a m p l e s t r e a t e d w i t h 0 . 0 8 m o l / 1 N a 9 S0 j a t Arrhenius law , this statement 1 3 0°C a n d 1 5 m i n u t e s w h i c h c o r r e s p o n d s t o t h e p r o c e s s curves like those in figure 4 - is bised upon 36 temperature . - . c o n d i t i o n s u s e d b y m o s t o f t h e CTMP p r o d u c e r s o f t o d a y F r o m a p r o c e s s p o i n t o f v i e w, i t i 6 i n t e r e s t i n g t o o b s e r v e that about 75 Z of the sulphonation achieved in 15 minutes i6 already achieved in 1 minute . Sulphur content , mmol / kg wood 70 60- o Sulphur content , mmol / kg wood 50- 70 605040 - 130°C O s o U' 40 - . 'o » * 70°C 30- JO* 20 20 10 10- 1 2 3 4 Figure 2 . Degree of sulphonation as a function of time sulphite concentration of 0.08 moles /1 , p H 9 . 5 a n d a t e m p e r a t u r e o f 1 3 0 C. ° a 276 5 6 7 0 9 10 11 12 13 14 15 Time, min 5 10 15 Time , mm at Figure 4 . Degree of sulphonation as a funktion time at a s u l p h i t e c o n c e n t r a t i o n o f 0 . 0 8 m o l e s / l , pH 9 . 5 , a t t e m p e r a t u r e s of 70 and 130 C. ° Effect of sulphite concentration observed , but the o b s e r v a t i o n s were made a t much longer The effect of sulphite concentration on the sulphite times than in the present case . . It is evident process content is illustrated in figure 5 that the sulphite concentration has a significant influen - Sulphur content , mmol / kg wood on the rate of the sulphonatlon reactions even a t short . e a c t i o n t i m e s. I n t e r m s o f C T M P p r o c e s s c o n d i t i o n s , a 80 - c h a n g e i n N a S0 j c h a r g e f r o m 2 X ( 0 . 0 8 m o l / 1 i n i t i a l l y 2 t o 4 Z ( 0 . 1 6 mol /1) w i l l I n c r e a s e t h e s u l p h u r c o n t e n t by 70 - * . Furthermore the results indicate that an increase in c o n c e n t r a t i o n f r o m 0 . 0 2 m o l /1 t o 0 . 0 8 m o l / 1 g i v e s r e l a t i v40 X pH = 8 0 8 e l y g r e a t e r i n c r e a s e i n sulphur content in the wood than o pH = 9 5 and pH = 11 0 50 - w h e n t h e c o n c e n t r a t i o n i s i n c r e a s e d f r o m 0 . 0 8 r a o l /1 t o - o 60 - 0 . 1 6 m o l / 1, t a k i n g i n t o a c c o u n t t h e f a c t t h a t t h e c o n c e n tration increase in the f i r s t case us four times and in 40 f7° the second case two times and that the sulphur content in t h e wood o r i g i n a l l y i s 7 m m o l e s /k g wood . 30 - J• 20 - a % Sulphur content , mmol / kg wood *' IQ- 90 0.16 mol / I 80 *• 5 10 15 Time , 70 - min . Degree of sulphonatlon as a function of time at %\ Figure 6 60 - 1 3 0° f 0 . 0 8 m o l e s / 1 s o d i u m s u l p h i t e a n d t h r e e pH l e v e l s ; 8 . 0 , 9 . 5 a n d 1 1 . 0 o . 0 08 mol / 1 9 50 40 - h Diffusion versus reaction kinetics - 30 - Since in t h i s investigation , the kinetics of the re 0 02 mol / 1 actions at short times are of 20 - primary concern it is essen - t i a l to know whether there i s any e f f e c t of diffusion on the reaction kinetics 10 - . In o r d e r t o e l u c i d a t e t h i s , we have determined the activation energies a t different degrees of i sulphonatlon by using an Arrhenius plot 5 10 15 shown in figure 7 Time , min . Figure 5 . The results are . I t i s evident that the slopes of In ( 1 / t ) versus ( i /T ), where t is time to a certain degree of sulphonatlon and T i s absolute temperature , are identical Degree of sulphonatlon as a function of time a t 1 3 0°C , p H 9 . 5 , a t t h r e e s u l p h i t e c o n c e n t r a t i o n l e v e l s: 0 . 0 2 , 0 . 0 8 and 0 . 1 6 (moles /1) . for a l l cases studied except for the case where the degree of sulphonatlon i s 20 mmoles /kg wood . T h e a c t i v a t i o n e n- ergy obtained a t 30 mmoles /kg wood o r higher i s 60 + 4 k J /m o l w h e r e a s a t 2 0 mmol /k g wood t h e a c t i v a t i o n e n e r g y i s about 20 kJ /raol . This indicates that the mechanism controlling the E f f e c t o f pH sulphonatlon i s d i f f e r e n t when the degree of sulphonatlon The e f f e c t s of pH o n t h e r a t e o f s u l p h o n a t l o n a t i s very low . The k i n e t i c s c o n t r o l l i n g the i n i t i a l phase of 1 3 0°C a n d a s u l p h i t e c o n c e n t r a t i o n o f 0 . 0 8 m o l e s / l a r e the process may be due t o d i f f u s i o n r a t h e r than t o t h e shown in Figure 6 chemical reactions . There seems to be no s i g n i f i c a n t dif - . f e r e n c e b e t w e e n t h e r a t e s o b t a i n e d a t pH 9 . 5 a n d 1 1 . 0 , b u t the rate of higher . - s u l p h o n a t l o n a t pH 0 . 8 i s s i g n i f i c a n t l y Time temperature s h i f t - For amorphous polymeric materials , the rate constant a t one temperature may be r e l a t e d t o the r a t e constant a t » o b s e r v e d t h a t t h e r a t e o f s u l p h o n a t l o n i s h i g h e r a t pH other temperatures by simply s h i f t i n g the time scale ( 13 ) From a master curve , the r a t e constant at verv long times T h e pH d e p e n d e n c e o f s u l p h o n a t l o n r a t e a t longer re action times has e a r l i e r been studied by Wenneras ( 12 ) , ?1 than t h e r a t e measured a t a pH lower t h a n 7 . At pH 7 o r higher ( up to 9 . 5) no difference In sulphonatlon rate was . o r a t v e r y 9h o r t t i m e s c a n h e a p p r o x i m a t e d c o n v e n i e n t l y b y the rate constant measured at any given temperature on 277 In ( l / T ) , m i n * Figure 8 shows the r e l a t i o n between the degree of ' . The ^ master curve i s constructed by s h i f t i n g the curves measured sulphonation and logarithm of the reduced time a / t -5 60 mmol / kg wood -4 at different temperatures horizontally along the time axis 50 mmol / kg wood -3 40 mmol / kg wood -2 until the curves f i t smoothly over one another using 130 C ° EA = 60! 4 k J / mol as the reference temperature for sulphite concentrations of 0.16 , 0.08 and 0.02 mol / 1 • 30 mmol / kg wood . * -i . Master curves are cpmstructed Na 2S03 a t a n I n i t i a l p H o f 9 . 5 I t can be seen that the curves f i t smoothly and thus 0 - the time temperature equivalence is applicable for the 1 Ea = 20 kJ / mol • 20 mmol / kg wood sulphonation reactions . The activation energy evaluated using the above equation is as expected identical with the 2 . . the activation energy for one evaluated in figure 7 , i e 2.5 2.6 2.7 2.8 25 3.0 Figure 7 . l / T, 10‘3 K - 1 the process i s 60 + 4 kJ /mol . F I N A L COMMENTS A p l o t of I n ( 1 / t ) v e r s u s l /T , i s shown f o r different degrees of sulphonation The sulphite c o n c e n t r a t i o n i s 0 . 0 8 rool / 1 a n d t h e i n i t i a l pH . As shown in f i g u r e 6, the r a t e of . s u l p h o n a t i o n i6 higher at a sulphite concentration of 0.08 and a temper 9.5 - 1 3 0°C w h e n t h e i n i t i a l pH i s 8 . 0 t h a n w h e n i t i s a t 9 . 5 or 11.0 Earlier investigations have shown that ature of . time scale - t h e r a t e d u r i n g t h e f i r s t h o u r o f s u l p h o n a t i o n a t pH 6 1 0 . Thi6 method i s in fact derived from the Arrhenius ’ law for chemical reactions 6 (1 2 ) A n u l o g u o u s l y t h e t i m e-t e m p e r a t u r e e q u i v a l e n c e p r i n - c i p l e may be a p p l i e d t o the k i n e t i c s of wood s u l p h o n a t i o n - The time temperature s h i f t factor a . 9) can be approximated ^ ( EA / 2 . 3 0 3 R ) • ( l / T -1 / TQ ) where EA stant . I t should be pointed out that in most of these studies only t h e i n i t i a l pH of the cooking liquor is mentioned i s w e l l d o c u m e n t e d t h a t w h e n t h e i n i t i a l pH o f . T i a r e a c t i o n t e m p e r a t u r e a t t i m e t a n d TQ i s the cooking - - d u r i n g cooking and more so when the cooking time i6 e x t e n 6 ded . the reference temperature at time t , both given in Q nificant effect on the resulting degree of sulphonation 150 - 1001 50 - 10 2 ' 10 ' ' 1 102 10 Time, min Figure 8 . Master curves for the degree of sulphonation versus reduced time a / for three i s u l p h i t e c o n c e n t r a t i o n s. S y m b o l s indicates temperature and sulphite concentration : ^ 0.16 0.08 0.02 moles /1 7 0° C Cl 9 0 °C - I t s e e m s t h a t t h e pH o f t h e c o o k i n g l i q u o r h a s a s i g . Sulphur content , mmol / kg wood 278 . It l i q u o r i s i n t h e a l k a l i n e r e g i o n t h e pH w i l l b e r e d u c e d i s the activation energy and R i s the gas con degrees Kelvin . However over longer sulphonation times , cooking in l o w e r pH r a n g e g i v e s a h i g h e r d e g r e e o f s u l p h o n a t i o n ( 7 , by the following serai empirical equation l o g aT - - i s i d e n t i c a l a n d t h a t t h e r a t e i s l o w e r i n t h e pH r a n g e 3 . 1 1 0° C 130 C A O A 9 ° . I Furthermore it Is well known that the temperature and - ionic strength affect the hydroxvl :on c ncent ation in * the liquor and the equlblibrium between sulphite and hydrogen sulphite ions, which would in turn affect the honation rate ( 15) . The degree of ionization of the phenolic and sulphite groups in lignin as a function of | pH , ionic strength and temperature might also be of im- . portance In order to achieve a complete understanding of the sulphonation reactions with wood , a further clarification of the effects of pH , ionic strength and temperature )dependence of these three parameters is necessary. The changes in diffusion rates may also be of interest. REFERENCES 1) FERRITSIUS, 0 and MOLDENIUS , S. Int. Mech. Pulping Conf. EUCEPA , Stockholm, May 6 10, 1985 2) HOGLUND, H, and BODIN , 0. Svensk Papperst 1 dning , 79(1976) 11 , 343 3) BEATM , L.R. and MIHLELICH , W.G. Int. Mech. Pulping Conf ., EUCEPA , Helsingfors, June 6 10, 1977 I I - M ATACK, D., HEITNER , C. and KARNIS , A. Pulp and Paper Canada , 82(1981) C/Convention 65 5) HEITNER , C. and ATACK , D. Int. Mech. Pulping Conf., EUCEPA Oslo, June 16-19, (1981) 6) HACGROTH , S., LINDGREN , B. and SAEDEN , U. Svensk Papperstidnlng 56(1953)17,660 - i’ I i - LINDGREN , B. The sulphonable groups of lignin , Dr.Thesis at the Faculty of Mathematics and Natural Science of the University of Stockholm , Sweden , (1952) 8) HEITNER , C., BEATSON , R.P. and ATACK , D. J. of Wood Chemistry and Techn. (1982)2 , 169 <0 BEATSON , R., HEITNER , C and ATACK , D. CPPA 69 Annual Meet. Feb. (1983) 10) RFATS0N , R , HEITNER , C and ATACK, D. Can. Mood Chem. Symp.(1982) U) SCIIONICER , W. Mikrochemlca Acta (1955)1 , 123 12 ) WENNERAS, S. I.P.C. 38(12) Abs 9155 (June) 1968 13) FF.RRY, J.D. (1970) Viscoeleasic properties of polymers, 2ns edn. Wiley 14) IITUN , M. The influence of drying strategies on the mechanical properties of paper. Dr. Thesis, The Royal Institute of Technology , Stockholm , Sweden , ( I 960) 15) TEDER , A. Svensk Papperstidning 75 (1972) 704 . k 279 EXPERIMENTAL - ULTRA HIGH YIELD PULPS FROM HARDWOOD THOMAS GRANFELDT AND RUNE SIMONSON DEPARTMENT OF ENGINEERING CHEMISTRY , CHALMERS ' TVERSITY OF TECHNOLOGY , S 4 12 96 G0TEBORG , — - DEN - GORAN BENGTSSON , EKA AB , S 445 0] SURTE , SWEDEN INTP.ODUCTION To give good chemimechanica 1 pulps (CMP) , high density hardwood chips need an alkali treatment prior to refining. For adequate softening , with out loosing to much in yield , about 3.5 to 4.0 - — wt. % sodium hydroxide is preferred. Unfortu nately , strongly colored chrorr.cphores are formed , resulting in low brightness pulps. - - During recent years , much effort has been direc ted to find pretreatment conditions which de crease the formation of chromophores. In this research , hydrogen peroxide has been used because it reduces chromophor production and is not harm ful to the environment. - - Hydrogen peroxide is known to readily decompose in alkaline solution at pH values near its pKa value. Penetration of a peroxide containing li quor into the chips is thereby substantially decreased. To overcome this problem , the avail 9 surface area of the chips has to be increas by using wafers , matchsticks or destructed chips in combination with silicate stabilizers. - - - - Earlier results obtained in our department have shown that for maximum pulp brightness gained with a certain amount of peroxide , the peroxide charge has to be split between the pretreatment stage and a conventional pulp bleaching stage. The work presented here has been concentrated on finding a method for production of CMP from European birch (Betula verrucosa ). The aim was to use sodium hydroxide and hydrogen peroxide for the pretreatment and , after a single stage refin ing , reach a high initial pulp brightness at a total yield above 90%. - By - - using a two stage impregnation method for the pretreatment with NaOH and H O., the risk of ^ d. Z peroxide decomposition should be minimized and , therefore , silicate stabilizers would not be needed. Norma 3 si zed chips were to be treated in conventional equipment for chemimechanica 1 pulp in - Inti. Symp. on Wood and Pulping Chemistry - The pretreatment of chips with sodium hydroxide and hydrogen peroxide respectivley , was carried out sequentially in two separate impregnation stages ( fig. 1 ). Two different methods of per forming the first stage alkali impregnation were elucidated : cold impregnation and screw press impregnation. Using cold impregnation , the atmos pherically steamed chips were directly soaked in NaOH solution for 10 min. at 20 °C. In the screw press impregnation , the steamed chips vWero corn pressed in a screw press type Impressa finer , before being fed to the soaking bin. The chips were then soaked for 3 min. at 20 °C. The liquor uptake in the cold impregnation was about 600 L/ ton , resulting in an average alkali charge of 3.8 wt. %. For the screw press impregnation , the corresponding values were 1100 I./ ton and 4.8 wt. % , respectively. - - - - - - - . - - - — FRESH CHIPS I STEAMING BIN Cold- impregnation SCREW PRESS SOAKING BIN SOAKING BIN NaOH 0RAINAGE BIN Screw - impregnalion NaOH PREHEATER * CHIPS TO REFINING DRAINAGE BIN SOAKING BIN SCREW PRESS Screw - impregnalion H2O2 Fig. 1. Pretreatment flowsheet for the two diffe rent two stage impregnation methods used in pilot plant trials. - - - In the following treatment , applied to both methods of impregnation , the chips were first drained for 15 min • r and then in a second im pregnation stage fed through a screw press and expanded in hydrogen peroxide solution. After soaking for 3 min. at 20 °C , the chips were drained for 3 min. The hydrogen peroxide charge was set by the concentration of the impregnating liquor. The preheating was carried out for 15 min. at 85 °C , followed by refining to different freeness values in a 36" double disc refiner with atmospheric discharge. The pulp consistency was about 20 %. - - - RESULTS AND DISCUSSION By using a screw press in the second impregna tion stage , excess alkali was removed from the chips and the pH of the chips before peroxide addition could be decreased below 11.5. Therefore , the peroxide charge could be chosen inde pendent of the alkali charge , without risking penetration obstruction caused by peroxide decomposition. - - 281 i - - The effect of the second stage screw press treat ment on pulp brightness after refining can be seen from fig. 2. For pulps A and D , the second stage impregnation was omitted and the chips were brought to the preheater directly after the alkali charging and subsequent drainage. The other pulps were impregnated with water or hydro gen peroxide solution in the second stage. For pulp B , in which case reaction products such as soluble chromophores have been squeezed out (25 kg/ton COD on o.d. wood) and replaced by water , the initial brightness gain compared to pulp A was 4 units. By adding peroxide to a consumption of 0.5 wt. % instead of water (pulp C), a fur ther gain of 5 brightness units could be achiev ed. through the refiner eye. No decreased energy requirement was found due to the higher , total alkali charge. Sodium hydroxide was twice as effective as sodium carbonate with regard to the development of strength properties. By adding 1 wt. % NaOH or 2 wt. % NanCO , tensile index and z strength could be increased by 25 % , i .e. the same gain as if all the alkali had been added during impregnation. If the refiner charge was lower than 1 wt. % NaOH , the bleachability was not affected. - - - - - Bright ness, */• TT !v 60 so 40 p 36 30 A 37 Impregnation — — NaOH , wt. % H O , wt• % ^^ * * "i Pulp brightness hotter bleaching with 3 wt - */• + 0 37 OS B C - NaOH- - H?0, Cold- 51 S3 10 o E [ +4 | Initial pulp brightness '—' Screw - impregnation Fig. 2. The effect of the first and second im pregnation stage to pulp brightness before and after bleaching. NaOH charges and HnG consump 0 tions are given in the histogram. - - To reach a very high initial pulp brightness, the chemical charges had to be optimized. With a charge of 2.5 wt. % NaOH and a consumption of 3.2 wt. % H 70 ISO was obtain , ed but at the * 2 2' expence of strength properties which were some what lowered. — - ° - The maximum brightness gained after a subsequent bleaching with 3 wt. % H O can also be* seen 2 fiom the figure. When compared to a single stage impregnation with a mixture of NaOH and H O? and at a given total charge of hydrogen peroxide , the impregnation must be done in two stages to reach a final , maximum brightness. - ^ - ^ By this method it was also possible to reach very high brightness values. For the earlie r mentioned pulp with an initial brightness of 70 * ISO, a subsequent bleaching with 4 wt. % of peroxide resulted in a final brightness of 85 % ISO , at a total pulp yield over 90%. - To increase pulp strength properties without risking a too high pH of the chips before the peroxide addition and , consequently , peroxide decomposition , some additional a l k a l i was added 282 3.8 4.8 0.5 100 350 + 600+ 14 39 20 1030 26 45 25 100 350 1320++ 700++ 28 14 43 38 26 20 - - - - Screw Including 30 kWh /ton screw press energy . Including 60 + 30 kWh/ton screw press energy Table 1. impregnation Cold 0.5 Tensile index , kNm /kg Scatt. coeff. m 2 /kg Fine fraction , P200 , % l V •f ^ - Total energi , kWh / ton T •• * ‘V *• L - Freeness , mL CSF 80 70 - - . Effect of the two different first stage impregnation methods on unscreened pulp characteristics and energy requirement. - As shown in table 1 by comparing the first stage impregnation methods adopted , the screw press impregnated chips consumed up to 30 y e mei ent * gy to a certain freeness value or tensile index than the cold - impregnated chips did. According to the literature , undersized chips are known to consume less energy to a certain freene ss value compared to normal or oversized chips . Further more , when the alkali charge is increa sed in the present interval , the energy consumption is lowered and the tensile index is increased corn pared at constant freeness. Since the chips which have been screw pressed twice have a smal ler size and have been subjected to a higher alkali charge the energy requirement expected fox these chips should thus be lower than that for the cold impregnated chips. The opposite result obtained indicates that the way mechani cal forces are applied to the chips is important and differs between the impregnation methods. One explanation cf this result could be that when performing the first stage impiecjnation by means of the screw press , the chips are not chemically softened before the mechanical de struction. This might initiate an ur» favor ab 1 e fiber fjbei separation which requires increased refining energy to yield a low pulp freeness and a given tensile strength. - -- - - - - . - - - - - - flux rate. A Mathem atical Model for the Ultraf i 1tratio n of Pulp Mill Efflu ent Liquor s in this labora tory has deter = km In Cg/CB J - (1 ) mined that the empiri cal consta nt Cg for kraft lignin s and lignin sulpho nates is 320 g/1 and 260 g/1 , respec tively. The mass transf er coef Dougla s L. Woerne r 3 ^ ^ Joseph L. McCart hy Depart ment of Chemic al Engine ering Univer sity of Washin gton Seattl e , WA 95195 - ficien t is best determ ined from the Deissl er correl ation ( 3 ) and is typica lly about 50 L/m 2/hr for plate and frame module s and about 150 for tubula r units. The reject ion coeffi cient is an experi men tally obtain ed parame ter which descri bes the amount of solute which is retain ed by the membra ne as is shown in Equati on ( 2 ). For multi compon ent soluti ons , a reject ion coef ficien t can be determ ined for each solute or for - Abstra ct A model of the batch ultraf lIt rat ion opera tions of diafl 1 tratio n and concen tratio n has been develo ped. The model accura tely correl ates availa ble litera ture data and has been used to predic t the size and operat ion of some possib le batch ultraf iltrat ion opera tions of pulp mill ef f luents. - Keywor ds: Work Ultraf i 1 tratio n , kraft lignin , lignin sulpho nate Introd uction U 1 trafi 1 tratio n and simila r membra ne pro cesses are energy effici ent operat ions which are - findin g wideni ng applic ations in the con centra tion and purifi cation of macro molec ular nd colloi dal soluti ons In the pulp and paper - . indust ry , the princi pal applic ations appear to be: 1 ) concen tratio n of kraft bleach plant efflue nts ( KBE ) to reduc e evapor ator load , 2] purifi cation and concen tratio n lignin sulpho na tes from spent sulphi te liquor s (SSL), 3] pro ductio n of high molecu lar weight kraft lignin ( HMKL ) from weak or strong kraft black liquor ( KBL ), and reduci ng color , BOD , and COD from efflue nt stream s ( 1 ). At relati vely low pressu res , 134 kPa and above , the flux rate throug h the membra ne is - - - indepe ndent of the trans membra ne pressu re. This phenom ena has been attrib uted to the exista nce of a gel layer with a resist ance to flow simila r to a packed bed of solids (2). A semi empiri ca 1 relati onship , shown in Equati on l , descr ibes the concen tratio n depend ence of the - R -- = 1 “ • _ v cp / cB ( 2) t groups of solute s. In the ultraf iltrat ion of pulp mill liquor s , reject ion coeffi cients have been define d in terms of total solids , total lignin , each lignin specie s , BOD , COD, sugar s and organi c acids , and inorga nic salts , The reject ion coeffi cient is primar ily a functi on of the membra ne pore radii and the solut e s i z e , but operat ing condit ions such as temper ature , pH , - and trans membra ne press ure have been shown to play an import ant role (4 ). Mode 1 Descri ption Two major u 11 rafi 11 rat ion operati ons are batch concen tratio n and diafiI t rat ion , a washin g proced ure which remove s small solute s from large solut es. These operat ions are inher ently non steady state since the solute concent ration - and soluti on volume consta ntly change with time. These operat ions are typica lly perfor med in a variet y of appara tus which all have a block diagra m simila r to Figure 1. The overal l materi al balan ce of this system is shown in Equati on 3a in diffe renti al form and Equati on 3 b dV dt - =0 V( t > ( a ) presen t addres : s Depart ment of Chemic al Engine ering Unive rsity of Maine at Orono Orono , ME 04469 ?# i * - " JA - < 3a ) - = V( t i ) * (0 JA ) At ( 3b) in integr ated form with the assump tion that any small time interv al , At , the flux . in rate is consta nt A materi al balanc e can be writte n for each solut e in the system as shown in Equati on 4. Inti. Symp. on Wood and Pulpin g Chemis try 283 . u respe ctive ly . A tubul ar ultra filte r unit with 1200 m 2 of membr ane with a mass trans fer coeff icien t of 150 L/m ?hr will ui dCB V * p dV + V dC B JA ( l R )C - B dt LB At dt = (4) con . _ ( 5) The assum ption of const ant flux rate withi n a time step is usual ly valid if the con centr ation chang e withi n that time step is smal 1 . In the compu ter progr am , all initi al value s and calcu latio nal param eters are enter ed as well as limit ing condi tions. Initi al value s are the solut ion volum e , solut e conce ntrat ions , and solve nt addit ion rate. Caleu latlo na 1 param eters are the membr ane area , the mass trans fer coef ficie nt , Cg , the rejec tion coeff icien ts , and the time step size. The progr am itera tes on Equat ions 5, 1 , and 3b at each time step until two succe ssive calcu latio ns of C( t ) are withi n .1 % of each other. The progr am then calcu lates the conce ntrat ion of each mater ial in the per meate using Equat ion 2. The time since the begin ning of the run , the remai ning solut ion volum e , the flux rate , and reten tate and per meate conce ntrat ions are writt en into a file at each time step. The progr am conti nues to run until one of the limit ing condi tions are obtai ned. Final value s are speci fied for the maximum run time , maximum solut e conce ntrat ion , and the maxim um volum e reduc tion . obtai ned with conti nuous addit ion of solve nt at a flow rate less that that of the perme ate The produ ction of one ton per hour of HMKL - - - Mode 1 Appli catio ns »f * The model has been succe ssful ly used to simul ate data avail able in the liter ature for batch conce ntrat ion , diafi ltrat ion , and mixed mode opera tion. A previ ous publi catio n ( 5) demon strat ed the abili ty to model KBL opera tions. The abili ty to simul ate SSL batch con centr ation is shown in Figur e 2 using the data provi ded by Botti no (6 ). Some initi al con from weak black liquo r has also been exami ned and is prese nted in Figur e 4. Diffe rent membr ane areas have been exami ned to incre ase the purit y of the HMKL. The increa se in membr ane area from 60 m 2 to 125 m 2 produ ces a highe r purit y , lower volum e produ ct. Simil ar resul ts are not exhib ited when the membr ane area incre ased from 125 m 2 to 200 m 2, indic ating an optim al area may exist is . Notat ion A C( t ) C(t l ) - cg * , CP J ^m 0 R - V At - ditio ns and reject ion coeff icien t had to be assume d to obtai n an accep table fit to the data The model has been appli ed to the . - batch con centr ation of a kraft bleac h plant efflu ent. A base case was assum ed at 416 ,666 L of efflu ent at a ligni n conce ntrat ion of 15 gL~ 1 and 30 gL“ i of non ligni n solid s with reject ion coeff icien t 284 . cB J - - - - - - - 0) it ] - Sever al schem es to produ ce a conce ntrat ed purif ied ligni n sulph onate from SSL have been simul ated. The initi al volum e of SSL was assum ed to be 100 ,000 L at a ligni n con centr ation of 60 gm/L and non ligni n con centr ation of 40 gm/ L with rejec tion coeff icien ts of 0.9 and 0.0 respe ctive ly. A tubul ar UF unit with 500 of area and km = 150 L/m ‘hr was assum ed , The resul ts of these simu latio ns are shown in Figur e 3 and demo nstr ate that the highe st purit y and lowes t volum e can be obtai ned by a flow manag ement which alter nates conce ntrat ion and diafl 1 trati on , with the first and last steps being batch conce ntrat ion. These resul ts sugge st that the best fluid manag ement to maxim ize purit y and minimiz e volum e may be rate withi n each diffe renti al time step At is const ant. This opera tion yield s Equat ion 5 - - centr ate this solut ion to 40 ,000 L and ligni n conce ntrat ion of 140 g/L in one hour. Equat ion 3a can be subst itute d into Equat ion 4 , and integ rated again assum ing that the flux C( t) « C( t l ) exp u. y ana u membr ane area m2 conce ntrat ion at time step t conce ntrat ion at time step t 1 conce ntrat ion in bulk solut ion 9/1 - conce ntrat ion of gel layer conce ntrat ion of perme ate flux rate mass trans fer coeff icien t solve nt addit ion rate rejec tion coeff icien t solut ion volum e time step size g/1 g/1 g/ i g/i l/m Vhr l/m 2/ hr 1/hr 1 hr References . | " ( EUP — MIXING CLAUSSEN , P• r ACS Symp. Ser . 154 ( Synlh . Memb • t Vol 2 ): 361 ( 1981 ). TANK 0 MICHAELS , A.S • f Chem. Eng. Prog * » 64( l 2 ) : 31 ( 1968). NAKAO, S• / NOMARA , T• t KIMURA , S• t 25( 4 ):615 ( 1979 ). AlChE J • t RETENTATE FEED F C ., F J* CR ' AIChE Symp. ULTRA' - PERMEATE j i L'TE R J Cp rigtre ]. Typica ] Block Diagram cf Ultrafi 1 tratior Batch Operation. . 310 • 1.0 V 0 L 270 , km l.u ? \ \ n u i R F L I \ U 0.8 sr T 0 0. Y A ~ y \ / - • frjtirr / XX 7 ? -• / corunirioi — \r X * I 0. « T C 0.4 T I R 150 0 N 0.2 *T I no .2 .4 .6 TIME (HOURS) .8 0 N 1.0 I C 0 N m 2 *> « x\ \ N c Y A lignin SSL at 10U g/l total solids on a 59 m 2 2 ot membrane with a ) « 0 m L = / /hr. P ( iig ^ in ; =.75 R ( non- lignir. solids ) = 0.0. •L 20 I F T R . Model Fit to Batcn Concentration of Bottino. Initial Values: 10 ,000 L of V 0 ,s P n U E R 0.6 Figure 2 Hm N 0.8 U SOLIDS COWCENTRAT ION L I G N 220 c 0 180 H Figure 4. Production of HMKL by Batch Concentra tion. Effect of membrane area. - C E so*# ** so**: . V 160 n T R 120 k I 0.2 I * X » 0H 1.0 2.0 Tint (HOURS) Figure 3. Model Fit of SSL production. Senes - * A Batch Concentration. Scheme B Batch concentra tion to 1/2 initial volume followed by tration to 90% purity then concentrate. - 285 I I I I I I I I I 1 They were isolated by CHC13 extraction of the filtrate and by analys s shovr. to have yields of 5.4 , 14.0 , 4.3 THE CATALYTIC HYDROGENOLYSIS OF WOOD AND ISOLATED l .l c IINS ^ and - 18.0* respectively of the chloroform dioxane extract and which had been shown previously to consist of essentially only lignin degradation products. J . M. PEPPER AND M.D. RAHMAN The following studies were monitored on the basis of the yields of these four compounds. DEPARTMENT OF CHEMISTRY UNIVERSITY OF SASKATCHEWAN SASKATOON , SASKATCHEWAN CANADA S7N 0W0 1. Similar treatment of isolated lignins ( Iotech , Stake and dioxane lignin) led to markedly reduced total yields ( * - caused had Lignin , a polypropylphenolic bipolymer is an abundant resource whose potential as a source of aromatic (phenolic) chemicals has received only minimum attention , It would 2. The degree of aqitation was important: decreased - agitation led to an increased abundance of the aryl substituted propanes (I and II) and a corresponding - and IV). fossil hydrocarbons as the primary source of carbon for - significant structural changes. decreased abundance of the aryl substituted propanols ( III appear inevitable that , in time , biomass will replace the organic based chemistry industry , 40%) indicating that the isolation treatment vs 12 3. It is therefore Consecutive five hour periods of either agitation imperative that methods be found whereby the lignin raw followed by no agitation or visa versa showed that the more material , either as a secondary product of the pulping highly reduced products (I and II ) did not arise by the industry or other biomass conversion processes, can oe initial production and subsequent reduction of the alcohols converted into compounds which can be used direct)/ or for (III and IV). which new applications can be found or which may a rve as 4. The catalyst was required but the ratio to wood was * ^ starting The objective of this research was to initial'* * study to determine the appropriate reaction conditions w/ Areby a degree of selective degradation of the lignin may t* achieved to produce a variety of products. fraction decreased as this ratio increased ; the total yields of compounds I ratio of increased as the ratio increased. - Chloroform extraction of the resuiting 5. Studies under initially alkaline conditions (addition of NaOH (4.5 g)/10 g wood meal in 150 mL solvent) gave - organo aqueous phase separated the lignin products which rise were analyzed by gas chromatography and mass spec* r'jmetry. Reaction parameters studied included: primarily to the ethyl derivatives ( V and VI). CH 3O H R lignin sour'>? ( native poplar wood or an isolated lignin ) , amount of catalyst , effect of agitation and the effect of th*r addition of alkali both with and without added antr.raquincne. Under previously published ( 1) [aspen wood meal (10 g)(containing - - dioxane water ( 1:1)( 150 mL) ; Rh C (5%) (1.0 g); VI R = 0CH 3 ; H ^ pressure 500 psi , heated in a rocking stainless s*« 'initial - bomb for 5 hours] the major monomeric products wer* - The following experiments were monitored on the basis IV. of the abundance of compounds V * VT . As before isolated lignins gave reduced yields over X) CH 30 HO R . wood itself CH 3 ii) Compounds V and VI were also obtained without added hydrogen but the yields were reduced. iix) I R =H II R = OCH 3 Subsequent treatment of the black liquor from an cC) in the presence of Rh -C (5%) catalyst , without added hydrogen , at 195°C gave - alkali anthraquinone pulping ( 170 rise CH 3O HO R' Ill R' = H IV R' = OCH 3 H3 V R = H - "standard" cG'.cit 10ns: - 1.8 g lignin * - IV maximized at a wood catalyst 10:1 and the relative abundance of the propanols (III and IV) over the propane derivatives (I and II ) Catalytic hydrogenolysis in a dioxane water medium was the degradation technique used. - the amount of the chloroform dioxane soluble important: material for further synthesis. to monomeric lignin degradation products. Mechanisms are proposed for the production and CH 2OH I n t i . Syrup . on Wood and P u l p i n g Chemistr relative abundance ot the lignin derivatives. 1 - J.M. Pepper and R.W. Fleming , Can. J. Chem. 5b , $96 898 (1978) . 287 I of chromophores in GP lignin might give considerable influ - ences on nitrobenzene oxidation , vanillin yields wer ^ determined before and after the treatment . Fig . 4 showed NITROBENZENE OXIDATION OF GROUND WOOL LIGNIN Masashi Sumimoto and Hidenori Hirashima Faculty of Agriculture , Kyushu University , Higashi - ku Hakozaki , Fukuoka 812 Japan KEYWORDS : GP bleaching . Alkali darkening , Reflectance , remarkable differences in the yield among treated samples of GP , TMP , and wood meal , in spite of very l i t t l e difference among unterated ones . This suggested the significance of mechanochemical conversion of lignin occurred in GP produc tion . Not much deviation of TMP lignin from wood meal lignin was also indicative from the point of view . S . Hosoya et al . mentioned about importance of a- carbonyl group as a reaction site with where Dakin type splitting took place at either C -j - C or C - Cg depending ^ ^ Nitrobenzene oxidation , Vanillin yield . on the nature of para - substituents as shown in fig. 5 . At least a part of the great decrease in vanillin yield after 1 . INTRODUCTION the Though i t i s generally believed that some mechanochemi - treatment might be caused by the type of splitting . However , treatment of GP with either NaBH ^ or NaOH also cal conversions of lignin molecules must have occurred brought about remarkable decrease in vanillin yield . This during ground wood pulping , there is almost no information might imply the presence of special atomic groups formed in GP lignin requiring more investigations . about what kinds of conversion occur and how they partici pate in pulp bleaching . In the present report , therefore , To find out the relationships between chemical changes in vanillin yield on oxidation of GP with nitro - characteristics of these treatments and vanillin yield , benzene were compared as an indicator to find out the treatment with difference between GP lignin and wood lignin . Changes in treatment with either NaBH reflectance of a sheet of treated GP were also compared by using A ( - log R® ) to find out the cause for alkali darkening in GP bleaching. for 30 , 60 , and 90 min and consecutive or NaOH under certain conditions ^ oxidation . As shown in fig . 6 , were followed by nitrobenzene gradual decrease in vanillin yield was observed . When treatment with NaBH of 0.5 % was followed by Ho 0 ? treatment , ^ an unusual increase in vanillin yield was found as shown in 2 . RESULTS AND DISCUSSION 2.1 . An origin of alkali darkening in the GP bleaching . Though consumption of H O ^^ in GP bleaching increased fig . 7 . However , this is not the case for the consecutive NaOH treatment . A partial reduction of carbonyl groups with NaBH , therefore , resulted in considerable stability of the ^ with running up the temperature , brightness of the resultant product against H O . The order of decrease in vanillin pulps leveled off as shown in fig . l . After the treatment of yield due to single treatment was Ho 0 > NaOH> NaBH , as shown GP with H O , NaBH , and NaOH , reflectance R in fig . 4 . However , any of double treatments lowered vanillin were measured , 2 2 ^ ^ and - log R and the difference before and after treatment , ^ i . e . A ( - log R c S E a in - o 0 - »« c —- 23 t JZ a> 60 - i GO OR u c ( OC H3 SO 3 x ft = H or CH i so 100 ISO Reacti on time ( m i n. ) 0 Fig . 5 Fig. 1. Consu mption of H Op by GP a t d i f f e r e n t temper ature and brightn ess of the resulta nt GP ^ £ 04 RV \ t 03 \ J * * » % ( B) l * &) ^ N 0 - J (C > c 1X3 =\ r — 0 - Q lb i- o ° 400 — SL c) / 21 1 v c (b ) c 0» 500 500 400 600 1 Added amoun t of NaBH ^ - 015 - ^- ^- . 0 10 Treatme nt 000 ) 11044 ? ( 100 ) 30 6 38 ? 9 ( 35 ) 70 * ( 46 ) 10 4 l?t ? Ml ) 6 70 * ( IS) 3 tl (5 ) RTC > Si ? (5 ) 0 5 ?4 f 6 ( ) (? ) 1 RTC > ?7 *5 4 10l4 haBH bl 1 SH ( 13 ) 4 3 RTC > ( 16 ) 9;5 0« ) ?|3 ( 71 haOH 2 70 65« 11 NaOHf 1 ( 100 ) 110*4 ? ( 100 ) ?o 70 74 * 15 ( 114 ) I?0j50 ( 109 ) 1 "A * V j* ’’ Wavel ength ( nm ) . . haBM 4 - - ^ .. - 4 o +2 o -* 4 *0 — C* » Qj «e *4 c c * IQ > -6 • — Treatm ent Treatm ent Treatm ent H, NaBH NaOH 2 - 02 7, VJ 7s - 10 r- - 12 - 7s. i V g 4 55 55 ,- those reaction products with H 0 • 4 Treatmen t with H^ O ? ? Residual Residual model Recovery H 0 (l) compound (I) ratio of the ? ? product ( 1) 2 7A hitrobenre ne oxidation Vanillin ( «/ *. *> Hodel { ( I ] b> Reaction product f ror modr : £ 11 J 0 JfO. 5 27 85 t 5 108 Wide I [ I I I ] * Notes : E Z3 GP , TMP f wood mt'ii 1 . ^ < b ) Treated for 60 win c ) RT ROOM temperature d ) Calculate d as free coniferyl aldehyde [ ] I e ) Calculate d as coniferyl aldenyer in parentheses are based on untreated pulp to be 100% ! Chang e i n vanilli n yield a f t e r the treatm ent of GP , TMP , and wood meal with , NaBH , and NaOH , 290 * . . holes ; a ) Treated for 90 «1n Compound 4. L . ) lable 2 . Vanillin yield from the model compounds and i * I% -8 ft CT c:' I iq ^ — - 2o 1X3 • . bl haBn b Fig 3 Differe nce curve betwe en [ log R ] a f t e r bleach ing ^ of GP with either Ho 02 ( A ) , or NaBH B ) and that a f t e r the post treatm ent of bl eached GP with 20% NaOH * Treatm ent time with ( min ) * Added amoun t of NaBH U t o pulp ) 3 6S±11 7 Q O5 500 Wavel ength ( nm ) 35 I Untreated 400 3 [ A ]01 . ( 6 ]f l umol / g ( 1 igntn ) O 500 Tetap CO structure In GP lignin Residual coniferyl aldehyde 1 c C7> t on pulp _ u«ol / g ( 1 iqnm ) 8 450 3 ^ Table 1 Change 1n content of coniferyl aldehyde 400 2 ( % t o pulp ) Fig . 7 . Chang e i n v a n i l l i n y i e l d from treated and untrea ted GP. Notes : a ) Treatm ent with differe nt amoun t of NaBH ( ) for 60 min . b ) Treatm ent ( a ) as a pre - treatm ent followe d by treatm ent with 3% HpC KD ) at 60 ° C for 90 m i n . c ) Treatm ent ( a ) as a p r e treatm ent follow ed by treatm ent w i t h 21 NaOHi —( ) at 70 C, C for 90 min. 600 Wavele ngth ( nm ) Wavel ength ( nm ) r i g. 2 . Chanqe i n [ log R«] ( A ) by the treatm ent of GP ( a ) with Hn(L ( b ) , NaBH. ( c ) , and NaOH ( d ) , and the differe nce ^ curve ( B ) . ( e ) : BKP . O T d) , -5 ° 23 - ' >> C / J T 25 a> * C > ~ C ^— — 24 7 / " fC -*8.) o -o - / ^ . T C •r cr Q > r~ c c • o •* m c =o « C\J 70 C Q> O BC C\J I I c TD • 23t (J in in OJ — —' XX ** SO c o I I o 70*C I I c 100 o Reaction product f roe> mode 1 [ i l l] • londitlond . . 94 Relative vanillin yield (l ) 48 * ? 100 ? 4l? 50 401? 100 35|? 73 Hodel compound concentra tion 0.005 r l H O. concentra tion 0 01 mol / t * / ^ Reaction tlmr 90 Min AUal *> a ? 6i 0 ] Solvent ttOfi 0* 1 ; Temperatur e 70 * C Imtal p 10 5 ( without ItOn) ' N *, . . ( 9) The present study was undertaken to deter - EFFECT CF ETHANOL ON SODA AN ~’HRAQUINONE PULPING Gladys M. De Chacon University of the Andes Merida , Venezuela - Yuan Zong Lai Empire State Paper Research Institute SUNY College of Environmental Science and Forestry Syracuse , New York 13210 - mine the effect of ethanol on the overall perfor mance of A0 additives in alkaline pulping . After completion of this study , some related work along this line has been reported by Abbot and Bolker ( 10 ). They showed that presence of ethanol in soda AQ cooks significantly enhanced the initial phase of de 1 ignificat ion , but severe ly reduced the effectiveness of AQ during the later stage of pulping . Our study has also in cluded a variety of AQ derivatives ranging from soluble AQ 2 su 1 fonate ( AMS ) to insoluble 2 , 3 ,6 ,7 tetramethy 1 AQ. The role of ethanol is discussed with respect to both de 1 ign i ficat ion efficiency and carbohydrate stabilization . - ABSTRACT The catalytic effects of various derivatives of anthraquinone ( AQ ) in soda pulping of Norway spruce have been studied with varying propor tions of ethanol and water. In general , it was found that the most prominent effect of the sol vent was an enhancement of carbohydrate stabili zation , notably in the case of insoluble 2 ,3 ,6 ,7 tetramethyl AQ. The influence of ethanol on de 1 iqnification efficiency was complex and var ied widely with different additives , 11 was clearly shown that a high alcohol concentration ( > 50%) drastically reduced the effectiveness of add it ives . The observed solvent effects did not display any simple relation with increased solu bility reflecting the importance of other fac tors involved. - - - KEYWORDS: Soda Pulping , AQ , Ethanol , AQ Deriv atives , Delignification , Carbohydrate Stabil iza tion. - - - INTRODUCTION The relative effectiveness of various anthra quinone ( AQ ) derivatives ( 1 ) are known to be influenced by both chemical and physical fac tors , notably solubility ( 2 , 3), redox potential ( 4 , 5 ), hydrophi 1 ICITY (6 , 7) and xylophi 1 icity ( 6 ). It is intriguing that the performance of AQ does not seem to be seriously limited by its low solubility in aqueous alkali , However , it has been shown that base catalyzed oxidation of simple sugars by AQ is accelerated substantially by the addition of ethanol ( 8 ). Moreover , the inability of 2 , 3 ,6 ,7 tetramethy 1 AQ to promote the delignification reaction in aqueous alkali has been ascribed to its insolubility ( 3). Conceptually , there are potential advantages in adding an organic solvent to soda -AQ cooks , as this would facilitate the dissolution and penetration of AQ into the wood chip , which have been shown to be a factor of critical importance - - - -- - EXPERIMENTAL - - Two series of soda pulping of air dried Nor spruce way wood were made. Extractive Free Wood - - Alkaline pulping of extractive - free wood meals or chips was carried out in small auto claves ( 75 mL ) in sodium hydroxide solution ( IN ) containing varying proportions of 95 % ethanol , ranging from 0 to 75 % by volume at a liquor to wood ratio of 40:1. The cooking temperature was at 160 C for 1 h . Cooks with various derivatives of AQ were made at a level of 5 % by weight on dry wood . The additives studied were AQ , a ser ies of 2 substituted AQ including the t butyl , ethyl , methyl , chloro , amino and sulfonate group , as well as 2 , 3 ,6 ,7 tetramethy 1 AQ which was generously provided by Dr. R .C. Eckert. Unextracted Wood Air dried chips ( 300 g ) were pulped in an M & K digester with a charge of 20 % NaOH contain inq an equal mixture of water and ethanol at a liquor to wood ratio of 5:1 with 0.1 % AQ charge and at 170 C for different periods of time. Similarly , another series of cooks were made with different AQ charge ( 0.01 5 % ) at 170 C for ° 90 min. - - ° - - - - - - - - - - ° - - - inti. Symp. on Wood and Pulping Chemistry RESULTS AND DISCUSSION Effect of Ethanol on Effectiveness of AQ Figure 1 illustrates the beneficial effect of ethanol on soda AQ pulping . It is clearly shown that the de 1 ign ification in a solvent system is much more responsive to an increase in the AQ addition , and levels off at a higher AQ charge ( 1 % vs. 0.5 % ). Presence of ethanol in creases the slope of the initial portion of the curve by a factor of 2. Thus , AQ is more effec tive in a solvent system probably attributed to - - - 291 an cation. It is likely that the relative effect iveness of various AQ derivatives in a solvent m the solubility of additive , For some reasons , Abbot and Bolker ( 10 ) observed a much smaller effect of ethanol on soda AQ pulp ing of black spruce matchstick sized chips con ducted at a lower temperature of 150 C. Effect of Ethanol on Soda Cooks with 5 % Additives increase - - - system is also controlled by the xylophi 1 icity . (6) ° Solubility , umol/L Additive Deliqnificatjon 0 - The complex pattern shown in Figure 2 indi c a t e s a strong interaction among the solvent , additive and alkali . First , the extent of alka line de 1 ignification is strongly enhanced by the I AQ Me AQ Table 1. ^ Second , the addition of ethanol to soda with various derivatives of AQ produced some rather interesting results , The delignifi cation efficiency of tetramethyl AQ , which is practically ineffective in aqueous alkali , in creases very distinctly with the alcohol addi tion up to 50 %. This observation strongly sup ports the contention that solubility can be a limiting factor for an additive with low solubil ity ( 2, 3). Third , it is very intriguing that the alka line delignification of woodmeals with both AQ and 2 butyl AQ ie essentially unaffected by the alcohol addition. In contrast to the behavior of woodmeals , ethanol is shown to greatly accel Grate de 1 ignification of chips with soda AQ ( Figures 1 and 2). It is noteworthy that delig nification for woodmeals is higher than that for chips in the aqueous system , while the reverse is true in the solvent system. - - - - - - Fourth , a similar pattern was obtained for 2 ethyl , 2 methyl , 2 chloro and 2 amino AQ ; the - extent of de 1 IGNIFICATION - increased significant - ly with the initial addition of ethanol , and tended to level off at about 25 % alcohol concen tration. It was also indicated that the deligni fication reaction gradually slows down as the alcohol concentration went above 50 %. Fifth , a close examination of the data in Table 1 and Figure 2 clearly indiates that solu bility is not the only dominant factor in a sol vent system. interest inqly , tetramethyl AQ , the least soluble additive , is the most effective one in the solvent system. Also , AQ , the most active additive in the aqueous system , becomes the least effective in the presence of alcohol. Thus , it appears that presence of ethanol also exerts some side effects which retard delignifi - l i i - 292 - The effect of solvent on the extent of carbo hydrate stabilization catalyzed bv the AQ addi tives can be seen clearly in Figure 3 , which - - - - ethanol cooks. The effectiveness of all the additives tested , with the exception of AMS , was substantially enhanced by the addition of ethan ol , notably , tetramethyl AQ , and 2 chloro AQ. These two additives qave a distinct maximum near 50 and 25 % alcohol concentration respectively . On the other hand , the solvent had a nega tive effect on AMS , and the carbohydrate stabili zation decreased steadily with increasing alco hoi concentration. This finding is in line with a previous report ( 11 ) that the presence of eth anol reduced the rate of oxidation of D qlucose by AMS in aqueous alkali. Thus , the maximum stabilization of carbohydrate requires an opti mum balance between the solubility of the addi tive and the rate of oxidation of carbohydrate end qroups. Effect of AQ ( 0.1 % ) on Soda Ethanol Cooks To assess the potential of soda ethanol pulp ing with the AQ additive , a series of experi ments were made in 50 % ethanol with 0.1 % AQ at 170 C for different periods of time , and com pared to control cooks without the additive , It was found that the rate of de 1 ignification was substantially increased by a small amount of AQ , a 66 % increase in the rate of bulk delignifica t ion. Also , the transition from bulk to resid ual delignification took place earlier ( 90 vs. 150 min ) and at a slightly lower lignin content. The use of AQ in this solvent system also result ed in higher pulp yields at a given Kappa number . The most beneficial effect ( 2 3 %) was found be tween the Kappa number of 40 and 70 ( Fiqure 4 ) Preliminary data indicated that the addition of - - - - - - - - - i 552 240 3.37 18.29 3.89 0.77 Approximate Solubility of AQ and 2 , 3 , 6 ,7 tetramethyl AQ in Ethanol NaOH Solution ( 1 N ) - - i 0.96 0.19 represents the net change in carbohydrate con tent with respect to the control soda and soda - I 71.25 Carbohydrate Stabilization COOKS I Ethanol , % 47.5 23.75 - addition of ethanol. There is an almost linear relationship between the lignin content of the pulp and the alcohol concentration. l - - - - - - - ° - - - - - . - AQ to soda ethan ol cooks pract icall y has no effec ts on the stren gth prope rty of pulp pro duced . addit ives. 3. - Tappi 64( 10 ):95 99 ( 1981 ). AMOS , L.W . and ECKER T, R .C• The influ ence of methy latio n on the solub ility and effi cienc y of anthr aquin one in soda pulpi ng . Exten ded abstr acts of 1982 Can. Wood Chem. / - CONCL USION S The above data clear ly show that the addi tion of ethan ol has a compl ex influ ence on the perfo rmanc e of vario us deriv ative s of AQ in alka line pulpi ng , The main featu res obser ved are brief ly outli ned in the follo wing. First, the most promi nent effec t of the sol vent is on the insol uble 2 ,3 ,6 ,7 tetra methy 1 AQ as refle cted in an enhan cemen t of both delig nifi catio n ( Figur e 2 ) and carbo hydra te stabi lizat ion ( Figur e 3 ). Such an enhan cemen t was mainl y due to an incre ased solub ility of the addit ive in a solve nt syste m. Secon d , the solve nt effec t on the stabi liza tion of carbo hydra te is also very prono unced for other addit ives with the excep tion of AMS ( Fig ure 3). It appea rs that ethan ol exert s some negat ive effec t by reduc ing the oxida tion effi cienc y of carbo hydra te end group s , Thus , the maxim um carbo hydra te stabi lizat ion requi res a prope r balan ce betwe en solub ility and rate of oxida tion , which seems to occur in the range of 25 -50 % alcoh ol conce ntrat ion. Third , the solve nt effec t on the delig nific a tion effic iency of 2 subst itute d AQ deriv ative s was mixed. A posit ive effec t was obser ved with a small addit ion of ethan ol , but a high solve nt conce ntrat ion ( > 50 % ) in fact hinde rs delig nific a t ion. The strik ing diffe rence betwe en soda AQ cooks of chips and woodm eals in respo nse to the alcoh ol addit ion sugge sts the impor tance of some physi cal facto rs invol ved. The poten tial role of prefe renti al alkal i sorpt ion and imbib ition of organ ic compo nents in a solve nt syste m by the cell wall polym ers need to be explo red furth er. Final ly , the remar kable effec ts of AQ addi tive obser ved in the aqueo us syste m have been shown to be appli cable to the solve nt syste m . - - Symp.:7 10 ( 1982 ). 4. - - FLEMI NG , B.I • KUBES , G.J . , MACLE OD , J.M • and BOLKE R , H.I • 9 Soda pulpi ng with anthr a 9 9 a mecha nism. quinon e - - Tappi 61( 6 ):4 3 4... ( 1978 ). - - 5. - 6. - - 7. 8. 9. FALK , L. E• SARKO , P • 9 BERGE R , M . I., and DENCE. C.W • 9 The effec t of anthr aquin one and anthr ahydr oquin one penet ratio n on de 1 ignif icati on in the soda pulpi ng of Norwa y spruc e. J. Wood Chem Techn ol 4( 1 ):35 59 9 - - . ( 1984 ) 10. ABBOT , J. and BOLKE R , H.I• 9 The influ ence of a secon d addit ive on the catal ytic actio n of anthr aquin one durin g delig nifi catio n . . DONNI NI , G.P • 9 BLAIN , T.J • HOLTO N , . , H H. and KUTNE Y , G.W• 9 300 Alkal ine pulpi ng addit ives: struc ture activ ity relat ion ships. Proce eding s of 6 th CPPA TS Annua l 9 Meetin g vol . 2: B95 -B101 1983 . ( - - ) - LOWEN DAHL, L. and SAMUE LSON , 0., Alkal ine treat ment of glyco lalde hyde , gluco se and cello biose in the prese nce of anthr aqui none . Acta Chem Scand B 33:531 536 ( 1979 ). - 11 . - Svens k Pappe rstid n 87( 12 ):R 69 R 73 ( 1984 ) - 2. ECKER T , R .C. and AMOS , L.W ., Influ ence of hydro phili city on the del ignif icati on effi cienc y of anthr aquin one deriv ative s. J . Wood Chem. Techn ol 2( 1 ):57 71 ( 1982 ). - REFER ENCES . - - - 1 WERTH EMANN , D.P. , The xylop hi 1 icity/hydro phili city balan ce of quino id pulpi ng addi tives. Tappi 64( 3 ).140 142 ( 1981 ). - - - - - - - - LINDE NFORS , S • 9 Addit ives in alkal ine pulp ing what reduc es what? Svens k Pappe rstid 83( 6 ):165 172 ( 1980 ). - VUORI NEN , T• Alkal i catal yzed oxida tion of D gluco se with sodiu m 2 anthr aquin one sul fonat e in ethan ol water solut ions. Carbo hyd Res 116:61 69 ( 1983 ). 9 - - - - WERTH FJ4ANN , D.P • The influ ence of solu bilit y on the effic acy of quino id pulpi ng 9 - 293 6 Q> •D >N O a 0 04 S - SODA EK)H * / ? 003 a> a> c j 8 a ° °? ooi - cr o oe 16 A0( chipr ^ o x: -o- a 2 C SOOA —- a o a o o v Ui 4 O O 0 i? ^ 24 2 40 SOuARF »00T or AO CHARGE / 1 7 j mmol/ 100 00$ wood 46 0 1 30 40 80 60 % E tho no ! , by volume j Figure 1. I -- The effect of ethanol (50%) on soda AQ delignification of unextracted Nor way spruce chips at 170R: for 90 min using a 20% alkali charge at a 5:1 liquor to wood ratio Effect of ethanol and AQ derivatives on carbohydrate stabilization from extracted Norway spruce woodmeals in IN NaOH at 160 C for 1 h. Data of soda AQ cooks of chips are also included Figure 3. ° - - - 60 / O NONE *O AMS A0 c Si &* 5 « a3.6.7- Me4 > ^ ^ -UJ> - <1 50 / oJ A0 ( chip ) 10 55 N N \ a o o > - / d 45 o Figure 2. I o I i 1 20 40 60 % Ethanolf vc ume I J 20 80 Effect of ethanol concentration and AQ derivatives on the lignin content of pulp from extracted Norway spruce woodmeals in IN NaOH at 160OC for lh. Data of soda AQ cooks of chips are also included O NaOH - EtOH NaOH - A Q (0 I % ) No OH- EtOH- AQ (01% ) Figure 4. 40 •I I 60 80 Kappa N a 1 1 /00 - - Effect of ethanol (50%) on the delig nification selectivity from soda AQ pulping of Norway spruce at 170 C ° - > I 294