Removal of Pb(II) from aqueous solution by using biochars derived from sugar cane bagasse and orange peel

In this study sugar cane biochar (SC-BC) and orange peel biochar (OP-BC) were used to remove Pb(II) ions from aqueous solutions. To achieve this goal, biochars were produced by the pyrolysis of biomasses at temperature less than 500 degrees C by using a small-scale biochar producing plant. Furthermore, batch adsorption studies have been performed, and the effects of several factors, i.e., pH, contact time, initial Pb(II) ions concentration and temperature were investigated on Pb(II) ions sorption mechanism and optimizing the removal efficiency of Pb. Boehm titration method and Fourier transform infrared (FTIR) spectroscopy were employed to quantitatively describe the major function groups on the surface of biochars. The obtained results revealed the presence of carboxyl, hydroxyl, and carbonyl groups, which are likely responsible for the adsorption of Pb(II) ions. Given the same chemical structure, SC-BC was more effective in removing Pb(II) ions than OP-BC, with the removal capacities of 86.96 mg/g, much higher than those of OP-BC (27.86 mg/g). The equilibrium data were well fitted with Langmuir model and the adsorption process was well fitted by pseudo-second-order model. We suggested the major adsorption mechanisms of Pb(II) ions through a specific ion-exchange mechanism, and surface precipitation. Results indicated that not only the chemical composition but also the morphological structure plays an important role in the sorption nature of biochar. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.