Adsorption of Cu(II), Co(II), and Ni(II) ions by modified magnetic chitosan chelating resin

Abstract

Cross-linked magnetic chitosan-isatin Schiff's base resin (CSIS) was prepared for adsorption of metal ions. CSIS obtained was investigated by means of FTIR, 1H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSIS resin toward Cu 2+, Co 2+ and Ni 2+ ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 103.16, 53.51, and 40.15 mg/g for Cu 2+, Co 2+ and Ni 2+ ions, respectively. Cross-linked magnetic CSIS displayed higher adsorption capacity for Cu 2+ in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSIS were regenerated with an efficiency of greater than 88% using 0.01–0.1 M ethylendiamine tetraacetic acid (EDTA).