Bentonite-Based Functional Material for Chromium Species Adsorption
Aminah, S; Buchari, B; Amran, M. B.

Abstract
A functional material (Bt-MCCs) for the simultaneous adsorption of trivalent and hexavalent chromium has been synthesized by modification of natural bentonite with cetyl trimethylamoniumromide and chitosan. This functional material was characterized by Fourier Transform Infra-Red, SEM and X-Ray Diffraction spectroscopy, while the evaluation of adsorption performance against Cr species was evaluated by batch method. The results obtained show that the adsorption of Cr species was influenced by pH, contact time, and initial concentration of Cr species. Langmuir and Freundlich models were used to evaluate the adsorption isotherm, and the adsorption kinetics was studied with pseudo-first and pseudo-second order kinetics models. The experimental data showed that the adsorption of chromium species followed well the Langmuir and Freundlich isotherms model, with adsorption capacity of 16.89 and 15.38 (mg/g) for Cr(III) and Cr(VI) respectively. The adsorption kinetics of chromium species by Bt-MCCs is best illustrated by the pseudo-second order kinetics model with the rate constants 0.0232 and 0.0024 (g.mg-1.min-1) for Cr(III) and Cr(VI). Bentonite modification with cetyl trimethylamonium bromide and chitosan provides adsorption capacity for Cr species much better than unmodified bentonite and capable for adsorbing both Cr species simultaneously from aqueous solutions.

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