Adsorption of Hg2+, Cu2+ and Zn2+ ions from aqueous solution using formaldehyde cross-linked modified chitosan-thioglyceraldehyde Schiff's base

A chitosan-thioglyceraldehyde Schiff's base cross-linked magnetic resin (CSTG) was prepared and characterized using various instrumental methods. Then, the prepared resin was used for comparative studies on the removal of toxic metal ions like: Hg2+, Cu2+ and Zn2+ from aqueous solutions. The effects of the initial pH value of the solution, contact time, the initial metal ion concentration and temperature on the adsorption capacity of the composite were investigated. The kinetics data were analyzed by pseudo-first order and pseudo-second order equations. The adsorption kinetics was well described by the pseudo-second order equation, and the adsorption isotherms were better fitted by the Langmuir equation. The maximum theoretical adsorption capacities of the CSTG resin for Hg2+, Cu2+ and Zn2+ were found to be 98 +/- 2, 76 +/- 1 and 52 +/- 1 mg g(-1), respectively. The negative values of Gibbs free energy of adsorption (Delta G(ads)degrees) indicated the spontaneity of the adsorption of all metal ions on the novel resin. (C) 2011 Elsevier B.V. All rights reserved.