Adsorptive Removal of Cr(VI) from Water by Anion Exchanger Based Nanosized Ferric Oxyhydroxide Hybrid Adsorbent

J. Ren, N. Li and L. Zhao

Abstract
A hybrid adsorbent (FOAE) prepared by loading ferric oxyhydroxide on anion exchanger was applied for adsorptive removal of Cr(VI) from water. Effects of initial Cr(VI) concentration, pH, temperature and competition of other anions on Cr(VI) adsorption were investigated in batch experiments. The equilibrium adsorption capacity (Qe) of the FOAE increased with initial Cr(VI) concentrations (from 20 to 100 mg L–1) and reached a plateau at the point of 100 mg L–1 with the Qe of 123 mg g–1. The optimum conditions for adsorption were determined as pH 2 and 313 K with Qe of 200 mg g–1. Competition effect of other anions on Cr(VI) removal can be concluded in the following order: PO4 3– > SO4 2– > Cl–. Cr(VI) adsorption on both FOAE and anion exchanger followed pseudo first order kinetic. Because the Freundlich isotherm could describe the adsorption of Cr(VI) on FOAE more adequately, it can be deduced that heterogeneous adsorption occurred on FOAE.

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Keywords
Cr(VI) removal, adsorption, nanosized ferric oxyhydroxide, anion exchanger