Abstract:To improve the adsorption performance of chitosan for heavy metal ions, the Ca2+ imprinted cross linked modified chitosan (CK) was obtained by Ca2+ imprint, glutaraldehyde crosslinking, freeze drying and carbon disulfide modification of chitosan (CS). The structure of adsorbents were characterized by FTIR, XRD and BET. The adsorption properties and mechanisms of Cd2+ were investigated by static adsorption experiment. The experimental results showed that the amino groups were successfully protected by Ca2+, the acid solubility of CS was improved by glutaraldehyde crosslinking (when pH=2, CK could be used), the specific surface area was increased to 272.82 m2/g and pore volume was increased to 0.44 cm3/g by freeze-dry method, and the C=S groups were successfully introduced by CS2 modification to improve the adsorption capacity of Cd2+ on CK. The Cd2+ adsorption capacity of CK was 49.43mg/g, adsorption capacity increased by 57.7% than that of CS. The adsorption of Cd2+ on CK was agreed will with the pseudo second order kinetics model, and the rate constant was 0.025 g/(mg•min). The adsorption of Cd2+ on CK accorded with Freundlich equation, and the n was 4.45. The Dubinin Radushkevich model indicated that the adsorption process of Cd2+ on CK was chemical adsorption, and the mean adsorption energy was 2236kJ/mol. The selective adsorption experiment indicated that CK had the properties of specific absorption with Cd2+, and the relative selectivity coefficients were greater than 3.54 besides Ca2+.