Evaluation of hybrid anion exchanger containing cupric oxide for As(III) removal from water

The aim of this study was investigate of arsenite adsorption on a hybrid polymer based on a polystyrene/divinylbenzene macroporous anion exchanger containing cupric oxide deposited within its porous structure. The study included batch kinetic and equilibrium experiments, and investigation of influence of the pH, regeneration of spent adsorbent and the column process on arsenic(III) adsorption. The experimental data were evaluated using kinetic, isotherm and fixed-bed column models. The adsorption capacity calculated from the Langmuir model was 6.61 mg As(III) g^-1. The adsorption rate was controlled by both chemisorption of arsenic on the adsorbent surface and external diffusion, and at a higher initial As(III) concentration also by intraparticle diffusion. The spent adsorbent was easily regenerated with 1.0 M NaOH solution. Based on batch adsorption studies and X-ray photoelectron spectroscopic analyses a mechanism of As(III) adsorption was proposed. Arsenite removal proceeded in two stages: oxidation to arsenate on the CuO surface, followed by an ion exchange reaction. The studied hybrid polymer also showed very good adsorption characteristics under the dynamic regime. The S-shape of breakthrough curves and insignificant influence of bed height, initial concentration and flow rate on the adsorption capacity confirmed its applicability in water treatment.