(573e) Adsorption of Arsenate Onto a Chitosan Based Polymeric Sorbent

Wei, Y. T., National University of Singapore
Zheng, Y. M., Natioanl University of Singapore
Chen, J. P., National University of Singapore

In this study, an efficient chitosan based polymeric sorbent was prepared for the removal of arsenic from aqueous solution. The sorbent was prepared through reaction of chitosan with certain reagent which is enriched with amine and hydroxyl groups. To evaluate the adsorption performance of the sorbent, isotherm and kinetics studies were carried out, effects of pH, natural organic matters (humic acid) and co-existing anions on the adsorption of arsenate onto the sorbent were investigated. The sorbent was found to be effective to remove arsenate from aqueous solution with a maximal adsorption capacity of 0.9 mmol-As/g-sorbent, which is better than that of most of the sorbent available in the market. Kinetics study showed that most of the uptake of arsenate on the sorbent took place in the first 5 h, and the adsorption equilibrium could be obtained within 16 h. An intraparticle diffusion model was successfully used to predict the adsorption kinetics of arsenate onto the sorbent under different ionic strength. Experimental results also showed the sorbent could be used for removing humic acid from aqueous solution. Competition adsorption experiments demonstrated that the presence of sulfate anion in aqueous solution significantly decreased the adsorption of arsenate onto the sorbent, while the effects of fluoride and phosphate anions on the arsenate adsorption were minor. Furthermore, FTIR and XPS analyses have been used to probe the interaction mechanism between arsenate and sorbent. It was found that electrostatic attraction between arsenic and active sites of the sorbents played a major role in sorption process.