Abstract
The production of biosorbents by waste biomass has attracted considerable attention due to the low cost and abundance of the raw materials. Here biochar produced from Eucalyptus camdulensis sawdust (EU-biochar) via pyrolysis at 600 degrees C was used as a potential biosorbent for Ni2+ and Pb2+ metal ions from wastewater. Characterization experiments indicated the formation of C- and O-bearing functional groups on the EU-biochar surface, while shifts and changes in the shape of C-H bands suggested the adsorption of Ni2+ and Pb2+ onto EU-biochar by interacting with surface carboxylic groups. Pb2+ was adsorbed more quickly than Ni2+, indicating a faster and stronger interaction of Pb2+ with EU-biochar compared to Ni2+. As the initial concentrations of both metal ions increased, the percentage removal decreased, whereas increasing the EU-biochar dose improved the percentage removal but impaired the adsorption capacity for Ni2+ and Pb2+. The adsorption capacity could only be improved without affecting the percentage removal of both ions by increasing the pH of the metal solutions. The sorption efficiency of EU-biochar and the removal mechanism of Ni2+ and Pb2+ were further explored using non-linear and linear forms of kinetic and isotherm models.