Amberlite IRA-900 Ion Exchange Resin for the Sorption of Selenate and Sulfate: Equilibrium, Kinetic, and Regeneration Studies

Abstract

The synthetic strong base anion-exchange resin Amberlite IRA-9 was investigated for its adsorption capacity to simultaneously remove selenate (SeO42−) and sulfate (SO42−) from single and binary anion solutions at pH 7.5 and 2°C. At an initial SeO42− and SO42− concentration of 428.9 and 1,441.1 mg/L, respectively, IRA-9 adsorbed 85 (±1)% SeO42− and 75 (±5)% SO42− from single anion solutions at 2% (w/v) resin dosage. In binary anion solutions, a 2% decrease for both the SeO42− and SO42− adsorption efficiency was observed. Batch kinetic experimental data indicated that the adsorption rate of IRA-9 for both SeO42− and SO42− in the single and binary anion solutions fitted well to the pseudo-second-order kinetic model (R2=.99). The modified Langmuir isotherm complete competition model best fitted the experimental data for binary anion solutions, showing 24% and 1% average relative error from theoretical calculations for SeO42− and SO42−, respectively. Exhausted resin was regenerated for the next cycle of adsorption using either .25 or .5 M HCl for 2 min and was tested for 3 adsorption-desorption cycles. Results showed that the resin was suitable for reuse at an optimal adsorption-desorption of 6 cycles without compromising the removal efficiencies. Efficient and fast adsorption of both SeO42− and SO42− is promising for developing an IRA-9 based ion-exchange process for the remediation of Se-contaminated (waste)waters.