高容量亚胺基二乙酸型螯合树脂的制备及吸附性能

以甲基丙烯酸缩水甘油酯(GMA)为单体, 氯甲基化的交联聚苯乙烯树脂(CMCPS)为大分子引发剂, CuBr/2,2'-联吡啶(Bpy)为催化剂, 采用表面引发原子转移自由基聚合(SI-ATRP)技术, 使甲基丙烯酸缩水甘油酯聚合在CMCPS树脂表面, 制得了环氧化聚合物. 将该聚合物与亚胺基二乙酸(IDA)反应, 制备了高容量亚胺基二乙酸型螯合树脂(IDA-PGMA-CMCPS), 用元素分析对其进行了表征. 考察了螯合树脂对Cu²⁺的吸附性能及动力学和热力学参数. 该螯合树脂表面IDA接枝密度达8.15 mg/m². 研究结果表明, 树脂对Cu²⁺的吸附量随离子浓度和温度的升高而增加, 当pH值为2.2时, 对Cu²⁺离子的吸附效果最佳. 树脂的静态饱和吸附容量为1339.66 mg/g, Langmuir和Freundlich方程均呈现良好的拟合度. 通过热力学平衡方程计算ΔG<0, ΔH=270.60 kJ/mol, ΔS>0, 表明该吸附过程是自发、 吸热、 熵增加的过程. 动力学研究结果表明, 准二级动力学方程能较好拟合动力学实验结果, 该过程符合准二级动力学模型.

Preparation of High-capacity IDA Chelating Resin and Its Adsorption Properties

A new high-capacity iminodiacetic acid(IDA) chelating resin was synthesized via surface-initiated atom transfer radical polymerization(SI-ATRP) method. Glycidyl methacrylate(GMA) was grafted onto the surface of the chloromethyl polystyrene resin by SI-ATRP using the organic metal compound formed in the CuBr/2,2'-bipyridine(Bpy) system as catalyst at room temperature. The IDA chelating resin was synthesized by grafting IDA on the surface of polyglycidyl methacrylate(PGMA) modified polystyrene resin. The chelating resin was characterized by means of elementary analysis, and evaluated in details to determine its adsorption properties and parameters of kinetics and the thermodynamics. The amount of IDA on the surface of polystyrene resin was calculated to be 8.15 mg/m2. Adsorption capacity of copper(Ⅱ) increased with increasing initial metal ion concentration and temperature, and its highest adsorption capacity was 1339.66 mg/g at pH=2.2. The experimental results showed that the equilibrium adsorption data fitted well to both Langmuir and Freundlich isotherms. The thermodynamic equilibrium functions were also determined. ΔG<0, ΔH=270.60 kJ/mol, ΔS>0, so the adsorption was spontaneous, endothermic and entropy increasing. The kinetic experimental data were correlated with second-order kinetic model.