Adsorption of Chromium(VI) from Aqueous Solutions Using Cross-Linked Magnetic Chitosan Beads

Abstract

The performance of a cross-linked magnetic chitosan (CMC), which has been coated with magnetic fluids and cross-linked with epichlorohydrin, has been investigated for the adsorption of chromium(VI) from aqueous solutions. Infrared spectra of chitosan before and after modification show that it is a successful coating and that the cross-linking process has been effective. The influences of the pH of solution and the contact time on the adsorption amounts have been discussed, and the appropriate process conditions for the adsorption of Cr(VI) have been obtained. Scanning electron micrographs of the CMC before and after adsorption indicate that the reduction in the number of pores on the surface was due to the adsorption of Cr(VI). The adsorption experimental equilibrium data was found to fit the Langmuir model well, and the uptake of Cr(VI) was 69.4 mg/g. The experimental data for the kinetics of adsorption correlated well with the first-order Langergren rate equation, and Langergren rate constants have been determined. The adsorbed Cr(VI) ions can be removed from the exhausted CMC effectively by being regenerated with a 0.1 mol/L hydrochloric acid solution.