Ca2+印迹交联改性壳聚糖的制备及对Cd2+的吸附

Preparation of Ca2+ Imprinted Cross-linked Modified Chitosan and Its Adsorption Properties for Cd2+

采用Ca^2＋印迹保护氨基、戊二醛交联、冻干法造孔、CS2化学改性,制得了Ca^2＋印迹交联改性壳聚糖（CK）。并用FTIR、XRD和BET对吸附剂的结构进行了表征,通过静态吸附实验考察了其对Cd^2＋的吸附性能及机理。结果表明：Ca^2＋保护了氨基;戊二醛与壳聚糖（CS）发生了交联,改善了CS的酸溶性,pH=2时仍可使用;冻干法可使微孔比表面积增大至272.82 m^2/g,孔体积增大至0.44 cm^3/g;经CS2化学改性,成功引入了C=S基团,提高了CK对Cd^2＋的吸附性能,平衡吸附量可达49.43 mg/g,比CS的吸附量提高了57.7%。CK对Cd^2＋的吸附过程符合准二级动力学模型,反应速率常数可达25 g/（g·min）;CK对Cd^2＋的吸附过程符合Freundlich吸附等温式,n值可达4.45;Dubinin Radushkevich模型分析表明：CK吸附Cd^2＋的平均吸附能为2 236 kJ/mol,是化学吸附;选择性识别实验结果表明：CK对Cd^2＋具有选择吸附性,除Ca^2＋外,相对选择性系数均大于3.54。

The Ca^2＋ imprinted crosslinked modified chitosan（CK） was obtained by using Ca^2＋ as imprint ion to protect amino group glutaraldehyde as crosslinking agent,freeze drying and carbon disulfide as modification agent.The adsorbent was characterized by FTIR,XRD and BET.The adsorption properties and mechanisms of Cd^2＋ were investigated by static adsorption experiment.The experimental results showed that the amino groups were successfully protected by Ca^2＋,the improvement of acid solubility of CS was attributed to glutaraldehyde crosslinking.When p H = 2,CK could be used.The specific surface area was increased to 272.82 m^2/g and pore volume was increased to 0.44 cm^3/g by freeze-dry method.And the C=S groups were successfully introduced,which improved the adsorption capacity of Cd^2＋ on CK.The adsorption capacity reached 49.43 mg/g,which was an improvement of 57.7% compared with the adsorption capacity of Cd^2＋ on CS.The kinetic data were well fitted to the pseudo secondorder kinetics model with a rate constant of 25 g/（g·min）.The adsorption isotherm was well described by the Freundlich equation,and the n value was 4.45.The Dubinin Radushkevich model indicated that the adsorption was a chemical adsorption,and the mean energy of adsorption was 2 236 kJ/mol.The selective adsorption experiment suggested that CK exhibited a selective adsorption for Cd^2＋,and the relative selectivity coefficients were greater than 3.54 except Ca^2＋ .