Competitive adsorption of Pb2+ and Cd2+ on magnetic modified sugarcane bagasse prepared by two simple steps

Magnetic modified sugarcane bagasse with high adsorption capacity and rapid adsorption rate was prepared by two simple steps. Experimental results showed that the adsorption capacities of the magnetic sorbent for Pb2+ and Cd2+ were 1.2 and 1.1 mmol g(-1), respectively. Pseudo-second-order and pseudo-first-order kinetic model both could predict the adsorption and desorption kinetic process occurred on the modified sorbent. EDX analysis showed that Pb2+ and Cd2+ were adsorbed on the sorbent mainly through ion exchange. Competitive adsorption results showed that the presence of Pb2+ exerted a great inhibitory effect on Cd2+ adsorption, and the inhibitory effect increased with the increase of the initial concentration ratio of Pb2+ and Cd2+ (C-0(Pb): C-0(Cd)). Pb2+ could be selectively adsorbed by the magnetic sorbent when the values of C-0(Pb): C-0(Cd) was higher than or equal to 4:1. It was also found that Langmuir competitive model was suitable to predict the sorption isotherm in the binary system. The as prepared magnetic sorbent had a potential in heavy metal wastewater treatment. (C) 2012 Elsevier B.V. All rights reserved.