Cross-linked chitosan beads for phosphate removal from aqueous solution

Chitosan beads were cross-linked with glutaraldehyde (GA) and epichlorohydrin (EP), respectively, at variable composition. The general features of the adsorptive and textural properties of the bead systems were characterized using p-nitrophenolate (PNP) at pH 8.5. As well, a systematic adsorption study of phosphate dianion (phosphate ( HPO42-) species was carried out in aqueous solution at pH 8.5 and 295 K. The Sips isotherm model yielded adsorption parameters for the chitosan bead systems: (i) monolayer adsorption capacity (Q(m)) for PNP ranged from 0.30 to 0.52 mmol g(-1) and (ii) Q(m) values for the bead systems with HPO42- ranged from 22.4-52.1 mg g(-1) for these conditions. GA cross-linked beads reveal greater Q(m) values for PNP while EP cross-linked beads showed greater Q(m) values for HPO42, in accordance with the surface chemistry and the materials design described herein. The EP cross-linked beads show favorable adsorption-desorption properties and represents a promising tunable adsorbent system for the effective removal of phosphate dianion species in aqueous solution. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42949.