Adsorption Equilibrium and Kinetic Performances of Al-pillared Bentonite for Removal of Cadmium(II) from Aqueous Solutions

With synthetic wastewater, lab-scale batch experiments were carried out to investigate the adsorption equilibrium and kinetic performances of Al-pillared bentonite prepared using Na-volclay provided by Sudchemie AG for cadmium(II) removal from aqueous solution at room temperature. The effects of relevant parameters, such as pH value of solution, adsorbent dosage, initial concentration and contact time were examined, respectively. The experimental data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin-Redushkevich (D-R) isotherm models of adsorption. The maximum adsorption capacity calculated from Langmuir model was 0.030 mg.m(2). Cadmium(II) adsorption,was found to occur physically by D-R isotherm model. The kinetic data were analyzed using external mass transfer diffusion model for the first stage of adsorption and the intraparticle, mass transfer diffusion model for the second stage of adsorption. The intraparticle mass transfer diffusion model gave a better fit to the experimental data. Similar cadmium(11) adsorption capacity per unit surface area in comparison with Al-pillared smectite indicates that purifying doesn't improve adsorption performance of Al-pillared smectite to cadmium(II). Using Al-pillared bentonite to treat waste water containing cadmium(II) is economically feasible.