Competitive adsorption of Pb~(2+) and Cd~(2+) on magnetic modified sugarcane bagasse prepared by two simple steps

摘要

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 Pb~(2+) and Cd~(2+) were 1.2 and 1.1 mmolg~(-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 Pb~(2+) and Cd~(2+) were adsorbed on the sorbent mainly through ion exchange. Competitive adsorption results showed that the presence of Pb~(2+) exerted a great inhibitory effect on Cd~(2+) adsorption, and the inhibitory effect increased with the increase of the initial concentration ratio of Pb~(2+) and Cd~(2+) (C_0~(Pb): C_0~(Cd)). Pb~(2+) 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.