Adsorption of Copper (CU2+) Ions from Aqueous solution by non-crosslinked and crosslinked Chitosan-Coated Bentonite Beads

Ana Francia V. Mariano

(MS Graduated: 1st Sem 2008-2009)

Abstract

The adsorption of Cu2+ ions from aqueous solution by non-crosslinked and crosslinked chitosan-coated bentonite (CCB) beads was investigated in a batch system, including the effects of solution pH (1,2,3, 4 and 5), initial Cu2+ concentration (100,500, 1000 and 2000) and crosslinking at various contact times (30, 60, 1210, 240, 360, 720 and 1440 minutes). Epichlorohydrin was used to obtain beads that are insoluble in acidic solutions. Experimental results indicated that non-crosslinked CCB beads showed higher adsorption capacity compared with crosslinked CCB beads in the entire ranges studied. The initial Cu2+ solution concentration and the solution pH affected the adsorption capacity, i.e., increased initial Cu2+ concentration and pH resulted to increased adsorption capacity. The equilibrium data were analyzed using Langmuir isotherm model, with maximum monolayer adsorption capacities of 12.21, 10.50, 9.64 and 1.03 mg Cu2+/g CCB beads for non-crosslinked CCB beads and 9.43, 9.26, 8.42 and 2.61 mg Cu2+/g CCB beads for crosslinked CCB beads at pH 4,3,2 and 1 respectively. The kinetic data was tested using pseudo-first and pseudo-second order reaction which indicated that the chemical sorption was the rate-limiting step. The Cu2+ ions were desorbed from the crosslinked CCB beads by dilute HCL acid (pH 1), which suggested that crosslinked CCB beads can be regenerated and reused to adsorb metal ions for another adsorption cycle.