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+

摘要:

为提高壳聚糖( CS )对重金属离子的吸附性能，采用Ca2+ 印迹保护氨基，戊二醛交联，冻干法造孔， CS2 化学改性，制得Ca2+ 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 Cd2+ 的吸附性能及机理。实验结果表明，Ca2+ 成功地保护了氨基；戊二醛与CS 发生了交联，改善了CS的酸溶，pH=2时仍可使用；冻干法可使微孔比表面积增大至272.82 m2/g，孔体积增大至0.44 cm3/g；经 CS2 化学改性，成功引入了 C=S基团，提高了 CK对Cd2+ 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吸附 Cd2+符合准二级动力学模型，反应速率常数可达0.025 g/(mg•min)；CK 吸附Cd2+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Cd2+ 的平均吸附能为2236kJ/mol，是化学吸附；选择性识别实验结果表明，CK对Cd2+ 具有选择吸附性，除Ca2+外，相对选择性系数均大于3.54。

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+.