壳聚糖基复合物理水凝胶的制备及其重金属吸附性能

Preparation of chitosan-based composite physical hydrogel and its heavy metal adsorption property

为避免化学水凝胶吸附剂残留的有毒化学交联剂对环境造成二次污染的问题,同时克服膨润土作为水介质中的吸附剂吸附性能较弱且难以回收的特点,构建了壳聚糖/聚丙烯酸钠/膨润土(CTS/PAA/BT)复合物理水凝胶。利用X射线衍射、红外光谱和扫描电镜等手段对其进行表征;考察不同条件以及多元离子竞争对其吸附水中Pb^(2+)、Cu^(2+)、Cd^(2+)的影响,并通过吸附动力学,等温线和热力学的探究,了解其吸附机理。结果表明:在pH=5时最利于水凝胶的吸附,对Pb^(2+)、Cu^(2+)、Cd^(2+)最大吸附量分别为208.94mg/g、157.7mg/g、106.82mg/g,吸附过程是自发的、单层吸附,且以化学吸附为主;吸附容量受其他阳离子(Mg^(2+),K^(+))的影响较小,对去除水中重金属离子有着良好的应用前景。

In order to avoid the secondary pollution of the residual toxic chemical crosslinking agent accompanied by the chemical hydrogel adsorbent,chitosan/sodium polyacrylate/bentonite(CTS/PAA/BT) composite physical hydrogel,which possessed better collectability and adsorption performance than raw bentonite,was constructed.XRD,FI-IR,SEM and other testing instruments were used to characterize the hydrogel.The hydrogel’s adsorption of Pb^(2+),Cu^(2+) and Cd^(2+) in water under different condition as well as multi-ion competitive sorption were investigated,and understood the adsorption mechanism through the exploration of adsorption kinetics,isotherms and thermodynamics.The results shown that the maximum adsorption capacity of the hydrogel for Pb^(2+),Cu^(2+) and Cd^(2+) was 208.94 mg/g,157.7 mg/g and 106.82 mg/g,respectively.under the condition of pH=5.The adsorptions occurred spontaneously,which were not only monolayer adsorptions but also chemical adsorptions dominantly.Neither Mg^(2+) nor K^(+) had significant effect on the heavy metal adsorption of the hydrogel,which exhibited promising application prospect for removal of heavy metal ions from water.