壳聚糖/聚丙烯酸水凝胶的制备及对Cu2＋和Cd2＋的吸附

Preparation of Chitosan/Poly(acrylic acid) Hydrogel and Its Adsorption Properties for Cu^(2+) and Cd^(2+)

以丙烯酸(AA)和壳聚糖(CS)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,利用辉光放电电解等离子体(GDEP)技术在水溶液中一步引发制备了壳聚糖/聚丙烯酸(CS/PAA)水凝胶。采用FTIR、XRD和SEM对水凝胶的结构和形貌进行了表征,考察了溶液p H、吸附时间和初始质量浓度对Cu^(2+)和Cd^(2+)吸附的影响,探讨了水凝胶的重复利用性。结果表明:AA成功接枝到了CS链上,形成了具有多孔三维网络结构的CS/PAA水凝胶;该水凝胶对Cu^(2+)和Cd^(2+)的吸附符合准二级动力学模型和Langmuir吸附等温式;在最佳吸附p H下(p H=4.3),吸附120 min,CS/PAA水凝胶对Cu^(2+)和Cd^(2+)的最大实际吸附量分别为151.2和298.8 mg/g;该水凝胶在0.015mol/L乙二胺四乙酸四钠(EDTA-4Na)溶液中吸附解吸4次后,吸附量变化不大,说明CS/PAA水凝胶具有优异的再生和重复利用性。

The chitosan/poly （acrylic acid） （CS/PAA） hydrogel was synthesized in aqueous solution by glow-discharge electrolysis plasma （GDEP） technique, using chitosan （CS） and acrylic acid （AA） as materials, N,N＇-methylenebisacrylamide （MBA） as a crosslinking agent. The structure of CS/PAA hydrogel was characterized by FTIR, XRD and SEM. The effects of the solution pH, contacted time and initial mass concentration of Cu2＋ and Cd2＋ on the adsorption properties were investigated systematically. Moveover,the reusability of hydrogel was studied. The results showed that acrylic acid was successfully grafted into chitosan backbone. The hydorgel exhibited a three-dimensional network structure with a large number of pores on the surface. The adsorption of hydrogel for Cu2＋ and Cd2 ＋ was agreed well with the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacities of CuE＋ and Cd2＋ at pH --4.3 and 120 min were 151.2 and 298.8 rag/ g, respectively. CS/PAA hydrogel had higher adsorption capacities after four adsorption-desorption cycles using 0. 015 mol/L EDTA-4Na as eluent, suggesting CS/PAA hydrogel displayed excellent regeneration and reusability.