Chitosan resins synthesised by improved drop-sphere-forming method for Cr(VI) removal from aqueous solutions

An improved drop-sphere-forming (IDSF) method was applied to synthesise chitosan resin. Chitosan resin was synthesised by the self-made device and cross-linked with epichlorohydrin. The influences of concentration of chitosan-acetic acid solution, air flow, reaction time and the dosage of epichlorohydrin were investigated during synthesising. The satisfactory chitosan particles were prepared by chitosan-acetic acid solution (3%) under a controlled air flow of 0.6 m(3) h(-1), After 6 h of reaction at 80 °C with an epichlorohydrin dosage of 2 mL per 5 mL wet resin, the chitosan cross-linked resin has the best adsorption capacity. After 2 h of adsorption at pH = 3.0 and 25 °C with an adsorbent dosage of 2 g L(-1), the maximum adsorption capacity (112 mg g(-1)) was reached for an initial Cr(VI) concentration of 146 mg L(-1). Compared with other adsorbents, this synthesis method was simple and economic; moreover, the cross-linked chitosan resin can remove Cr(VI) efficiently.