The removal of Cr (III) from aqueous solutions and industrial effluents by biosorbents from wood

Chromium is a transition metal element but it is also considered a heavy metal due to its potential toxicity when discharged into the environment through effluent streams. Biosorbents such as wood sawdust, biochar, and ashes from industrial boilers and gasifiers are investigated here to remove chromium from the environment. The removal efficiency of Cr(III) from aqueous solutions using sawdusts and biochars from soft pine (SP), yellow poplar (YP), red oak (RO), and Douglas fir (DF) were improved after treatment with aqueous ammonia. Among them, the removal efficiencies were 51.14% and 50.92% using ammonia-treated SP and YP, respectively and at 99.95% and 99.41%, respectively for boiler and gasifier ashes. However, the boiler ash and ammonia-treated YP had lower biosorption abilities for Cr(III) in chromium-plating and tannery effluents compared to aqueous solutions. The complex composition of these industrial wastewaters and the presence of other metal ions may have influenced the chromium sorption. --Leaf [i]