Synthesis of a novel Ce(III)-incorporated cross-linked chitosan and its effective removal of fluoride from aqueous solution

A novel Ce(III)-incorporated cross-linked chitosan (Ce-CCS) was prepared and used for the removal of fluoride from aqueous solution. The structure and morphology of Ce-CCS were measured by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy dispersive X-ray analyzer (EDAX) techniques. The factors affecting the fluoride adsorption such as adsorbent dosage, initial fluoride concentration, pH, coexisting anions and contact time were investigated. Increasing adsorbent dosage enhanced the removal towards fluoride while increasing initial fluoride concentration reduced the removal towards fluoride. The optimal pH value for fluoride adsorption was 3 or so. The presence of coexisting anions weakened the adsorption of fluoride, and the decreasing order of the removal towards fluoride was PO43- > CO32- > SO42- > Cl-. The adsorption data were described by Freundlich isotherm model and the pseudo-second order kinetic model. The incorporation of Ce(III) enhanced the adsorption capacity of CCS for fluoride ions, the adsorption capacity at equilibrium (q(e)) of Ce-CCS increased by 5.0 mg/g or so as compared with the one of CCS at the same temperature tested. The exhausted Ce-CCS could regenerate with 0.1 mol/L HCl solution.