聚乙烯四唑型螯合树脂及其对重金属离子的吸附性能

采用表面引发原子转移自由基聚合(SI-ATRP)方法将丙烯腈(AN) 接枝到氯甲基化聚苯乙烯树脂(PS-CH₂Cl) 表面, 再与叠氮化钠进行3+2环加成反应, 制备了一种聚乙烯四唑型螯合树脂(PVT-g-PS). 用红外光谱和元素分析对PVT-g-PS树脂进行了表征, 考察了该树脂对Pb(Ⅱ), Ni(Ⅱ)和Cd(Ⅱ)的吸附性能. 在一定聚合时间范围内, 丙烯腈接枝率与SI-ATRP时间呈线性关系, 树脂表面四唑含量及树脂对金属离子的吸附容量随丙烯腈接枝率增大而增大, 说明丙烯腈在树脂表面聚合为活性可控聚合, 树脂表面功能团含量和树脂吸附容量可以用聚合时间调控. 通过分析树脂吸附容量与溶液pH值的关系、 吸附等温线和吸附动力学, 证明3种金属离子的吸附主要是基于配位作用的化学吸附. 当SI-ATRP时间为10 h时, 树脂对Pb(Ⅱ), Ni(Ⅱ)和Cd(Ⅱ)吸附容量高达1.57, 1.68和1.92 mmol/g. 经过10次吸附-解吸循环实验, 树脂的吸附容量无显著变化, 表明新型树脂具有较高的吸附量和良好的重复使用性.

High-capacity Polyvinyltetrazole-grafted Chelating Resin for Adsorption of Heavy Metal Ions†

A novel polyvinyltetrazole-grafted chelating resin was prepared by grafting poly(acrylonitrile) onto the chloromethylated polystyrene beads via surface-initiated atom transfer radical polymerization(SI-ATRP), and followed by the reaction of cyano-tetrazole conversion under microwave assistance. The structure of the resin was characterized by Fourier transform infrared spectroscopy and elemental analysis, and the adsorption properties were evaluated with Pb(Ⅱ), Ni(Ⅱ) and Cd(Ⅱ). It was found that an increase in the polymerization time leads to the increases in grafting degree of acrylonitrile, the binding amount of tetrazoles and adsorption capacities of Pb(Ⅱ), Ni(Ⅱ), and Cd(Ⅱ). The results suggested that the polymerization of acrylonitrile on the resin surface was a controllable living polymerization, and the binding amount of tetrazoles on the resin surface and adsorption capacity of the resins could be adjusted by the polymerization time. The adsorption of three metal ions was mainly regarded as chemical adsorption based on the coordinating effect by analyzing the relationship between adsorption capacity with the solution pH, adsorption isotherm and adsorption kinetics. At the polymerization time of 10 h, the maximum sorption capacities of Pb(Ⅱ), Ni(Ⅱ) and Cd(Ⅱ) were 1.57, 1.68 and 1.92 mmol/g, respectively. Ten adsorption-desorption cycles demonstrated that the resin possessed high recycling efficiency and stability and was suitable for efficient removal of metal ions from aqueous solution.