A magnetic ion exchange resin with high efficiency of removing Cr (VI)

Abstract

The removal of chromium ions is a major concern for the metal-processing plant. In this study, the magnetic ion exchange resin (MR) was prepared given the function of the ion exchange and magnetic separation. The adsorption characteristics of Cr (VI) by magnetic ion exchange resin were investigated. The ion type of resin, pH of solution, contacting time, initial Cr (VI) concentration and adsorption temperature were studied which showing a great influence on the removal of Cr (VI). Consequently, the adsorption capacity could reach the maximum 197 mg/g under optimized conditions. Langmuir and Freundlich isotherm models were used to fit the equilibrium data at 298 K. The result demonstrated that the adsorption equilibrium could be well fitted by the Langmuir models. Besides the pseudo-first-order and second-order kinetics models were used to fit the adsorption kinetics, the adsorption behavior could be well fitted by the second-order kinetics model which indicated that the adsorption process was chemical adsorption. The thermodynamic parameters ΔH, ΔS and ΔG were calculated at 298 K. The negative ΔG and ΔH values indicated that the adsorption process of Cr (VI) removal by MR was spontaneous and endothermic. The results showed that MR could keep a stable adsorption capacity and magnetism.