| 摘要: | The adsorption of Cu ions from aqesous solution by non-crosslinked and crosslinked chitosan-coated bentonite (CCB) beads was investigated in a batch system, including the effects of contact time (0.5, l, 2, 4, 6, 12 and 24 hours), pH of solution (1, 2, 3, 4 and 5), initial Cu ion concentration (100, 500, 1000 and 2000) and crossl inking. Epichlorohydrin was used to obtain beads that are insoluble in acidic solutions. Experimental results indicated that non-crosslinked CCB beads showed higher adsorption capacity than crosslinked CCB beads in the entire pH range studied. The initlal Cu solution concentration and the solution pH affected the adsorption capacity, i. e., increased initial Cu concentration and pH resulted to increased adsorption capacity. The equilibrium data were analyzed using Langmuir and Freundlich isotherm models. Equilibrium adsorption data correlated well with Langmuir isotherm model, with maximum monolayer adsorption capacities of 12.21, 10.50, 9.64 and 1.03 mg Cu/g CCB beads for non-crosslinked CCB beads and 9.43, 9.26, 8.42 and 2.61 mg Cu/g CCB beads for crosslinked CCB beads at pH4, 3, 2 and 1 respectively. The kinetic data was tested using pseudo-first and -second order reaction. The kinetic experirnental data followed pseudo-second order reaction which indicated that the chemical sorption was the rate-limiting step. The Cu ions were desorbed from the crosslinked CCB beads by strong HCI acid (pH 1), which suggested that crosslinked CCB beads can be regenerated and reused to adsorb metal ions. |
