Adsorption of arsenate and arsenite from aqueous solutions by cerium-loaded cation exchange resin

The removal of arsenic from water and wastewater is obligatory. Resin is one of the most effective adsorbents for the removal of arsenic. In order to improve the adsorption capacity of resin, a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin. Batch adsorption experiments under various conditions, such as time, temperature, pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As(V) and As(III) from aqueous solutions. The results showed that the adsorption kinetics of As(V) and As(III) obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g·mg−1·min−1, respectively. The adsorption of As(V) followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As(III) fitted well to the Langmuir equation model. The adsorption capacities were 1.0278 mg/g for As(V) and 2.5297 mg/g for As(III). Both the adsorption of As(V) and As(III) were found to be pH sensitive and the optimum pH was found to be 5-6. Except for the phosphate ion, the coexisting anionics, such as nitrate, chlorate, sulphate and carbonate, showed no remarkable effect on As(V) and As(III) adsorption. The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As(V) and As(III) could be restored to 97.80% and 69.61%, respectively, using 0.5 mol/L sodium hydroxide solution.