Sorption of Cr(VI) and Cu(II) by Chemical Modified Rice Hull

Abstract: The potential of using citric acid treated quaternized rice hulls (CQRH) as a sorbent for the removal of Cr(VI) and Cu(II) from synthetic single and binary metal solutions was investigated. Parameters investigated include pH, contact time, initial concentration and temperature. The results show that sorption was pH dependent and equilibrium was attained in less than 30 min. The sorption followed pseudo-second order kinetics. The sorption of Cr(VI) from single and binary metal ion solutions was found to be an exothermic and endothermic process, respectively, while sorption of Cu(II) was an endothermic process. For single metal solution, the sorption process conformed to the Langmuir isotherm model with maximum sorption capacities of 23.7 and 8.0 mg/g at 28±2°C for Cr(VI) and Cu(II), respectively. For binary metal solution, sorption capacity of Cr(VI) was 27.7 mg/g while that of Cu(II) was similar to that in single metal solution.