Title

Beneficial Utilization of Rice Husk Ash (RHA) as a New Sorbent for Removal of Antimony (III) from Water

Document Type

Article

Publication Date

4-16-2013

Abstract

This study represents the first scientific effort to evaluate the technical feasibility of rice husk ashes (RHA; ash burned after RH) as a new water treatment material for adsorption of Sb(III) from drinking water. Three RHA samples (RHA300, RHA450, RHA600) were prepared from RH at 300, 450 and 600 °C, respectively. Compared with RH, RHA had great specific surface areas, small particle sizes, and large total pore volumes. Moreover, the RHA was characterized by an amorphous structure. In the subsequent bench-scale tests, the RHA samples were utilized to adsorb Sb(III) from water. Kinetics tests showed that pseudo firstorder and pseudo second-order kinetics models both well fit the experimental data, and Sb(III) sorption rates followed the order of RHA450 > RHA600> RHA300 > RH. Among the 4 tested adsorption isotherm models (Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich), the Langmuir isotherm was the best one to fit the measured data, and the adsorption capacities of RHA300, RHA450 and RHA600 were 1.407, 3.842 and 2.731 mg/g, respectively. Solution pH, natural organic matters (NOMs) and certain cations (e.g. Fe3+ and Fe2+) were significant factors controlling the adsorption process. RHA300 adsorption was increased with increasing pH from 2 to 12, while RHA450 and RHA600 showed a high adsorption potential at pHs 4-10. Their maximum adsorption capacities were observed at pH values where the lowest zeta potentials were found. Fe3+ and Fe2+ both greatly inhibited RHA adsorption of Sb(III). In contrast, K+, Na+, Mn2+ and Cu2+, as well as humic acid (HA) (the major NOM fraction), had a minor impact upon the adsorption. Our results demonstrate that RHA is a technically effective sorbent to address the Sb(III) pollution in water.

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