Adsorption behavior of Cu2+ from aqueous solution on composite crosslinked chitosan-clay

Abstract

Copper ions have been concerned because its contamination caused adverse effects on both environment and human health. A biopolymer, chitosan, is considered to be an effective adsorbent in adsorption processes to remove heavy metal ions. Inexpensive and higher surface area materials, bentonite and kaolinite, were studied as supporting materials for chitosan to reduce the quantity of chitosan. Bentonite exhibited higher adsorption capacity for Cu²⁺ than kaolinite as supporting material. The effect of cross-linking agent for composite crosslinked chitosan-bentonite was investigated, consequently. Composite crosslinked chitosan-bentonite using ethylene glycol diglycidyl ether and epichlorohydrin as crosslinking agents (CCB-EGDE and CCB-ECH beads) improved adsorption capacity and adsorbent strength for Cu²⁺ removal from aqueous solution compared to composite crosslinked chitosan-bentonite using glutaraldehyde as crosslinking agent (CCB-GLA beads). Adsorption isotherm of Cu²⁺ fitted with Langmuir and Fruendlich for CCB-EGDE, CCB-ECH beads and CCB-GLA beads, respectively. Adsorption kinetics followed pseudo-second-order kinetic model with respect to Cu²⁺ concentration. Regarding to adsorption-desorption study, the effect of initial Cu²⁺, effect of pH, and continuous adsorption were also preliminarily investigated. Physical characters of adsorbents were characterized by zeta-potential, SEM, XRD, and BET corresponding to adsorption results