Abstract
In this study, a composite, chitosan-g-poly(acrylic acid)/ vermiculite, was prepared by aqueous dispersion polymerization using chitosan as the stabilizer, acrylic acid as the monomer and vermiculite as the inorganic additive. It was then cross-linked with common divalent or trivalent cations to obtain adsorbents with a higher affinity for phosphate ions. Factors influencing the adsorption capacity were investigated, the results indicating that the trivalent ion cross-linked hybrid exhibited a potential for the removal of phosphate ions and that a lower concentration of cross-linking agent could achieve the complete cross-linking of carboxylate groups within the composite. The adsorption of phosphate ions onto the developed adsorbent was pH-dependent, with a lower pH yielding a higher adsorption capacity. The Langmuir and Freundlich models were used to describe the adsorption data; the maximum adsorption capacity of 22.64 mg/g was comparable with that reported for other adsorbents. Desorption studies showed that the adsorbed phosphate ions were relatively difficult to remove from the hybrid material.