ZIF-8掺杂聚合物包容膜耦合电沉积分离Ag(Ⅰ)

Performance of Coupled Electrodeposition of ZIF-8 Doped Polymer Inclusion Membrane for Ag(Ⅰ)Separation

针对电沉积法回收工业废水中低浓度贵金属的纯度问题,在以聚氯乙烯(PVC)为基础聚合物、二(2-乙基己基)磷酸酯(D2EHPA)为载体的聚合物包容膜(PD-PIM)中,引入荷正电性金属有机骨架(MOFs)材料ZIF-8,并耦合电沉积技术研究其对Ag(Ⅰ)的分离和提取行为。采用ATR-FTIR、XRD、BET、SEM和Zeta电位分析技术表征ZIF-8及ZIF-PD-PIM的微观形貌、结构特征及界面性质;以Ag(Ⅰ)的渗透系数为考察指标,优化ZIF-PD-PIM体系中ZIF-8添加量、电压和电极面积,评价ZIF-PD-PIM耦合电沉积技术对Ag(Ⅰ)的分离选择性。结果表明,ZIF-8在PIM表面及内部分布相对均匀,有效提高了ZIF-PD-PIM表面的电荷,强化了Ag(Ⅰ)的分离选择性。电沉积耦合能提高PIM的传质速率,在1.5 V优化电压下,PD-PIM对Ag(Ⅰ)的分离因子下降,但ZIF-PD-PIM-2Z的渗透系数从6.93μm/s(无电压)提升至13.67μm/s(有电压),Ag(Ⅰ)相对于Fe(Ⅲ)、Zn(Ⅱ)、Cu(Ⅱ)、Cd(Ⅱ)的分离因子分别由无电压时的18.09、3.42、5.43、14.11提升至20.12、9.82、11.15、15.97。

To enhance the purity of low-concentration precious metals recovered from industrial wastewater through electrodeposition,a polymer inclusion membrane(PIM)composed of polyvinyl chloride(PVC)as the base polymer and di(2-ethylhexyl)phosphate(D2EHPA)as the carrier was developed by incorporating positively charged metal-organic frameworks(MOFs)ZIF-8,and its separation and extraction behavior of Ag(Ⅰ)ions were investigated through the coupling of electrodeposition.The microscopic morphology,structure,and interfacial properties of ZIF-8 and ZIF-PD-PIM were characterized using ATR-FTIR,XRD,BET,SEM,and Zeta potential analysis techniques.Using the permeability coefficient of Ag(Ⅰ)as a benchmark,the addition amount of ZIF-8,voltage,and electrode area in the ZIF-PD-PIM system were optimized,and the separation selectivity of Ag(Ⅰ)throughZIF-PD-PIM coupled electrodeposition was subsequently assessed.The distribution of ZIF-8 both on the surface and within PIM was relatively uniform,which significantly enhanced the surface charge of ZIF-PD-PIM and improved the separation selectivity for Ag(Ⅰ).Electrodeposition coupling enhanced the mass transfer rate of PIM.At the optimized voltage of 1.5 V,the separation factor for Ag(Ⅰ)by PD-PIM decreased.However,the permeability coefficient of ZIF-PD-PIM-2Z increased from 6.93μm/s(without voltage)to 13.67μm/s(with voltage).The separation factors for Ag(Ⅰ)in relation to Fe(Ⅲ),Zn(Ⅱ),Cu(Ⅱ),and Cd(Ⅱ)rose from 18.09,3.42,5.43,and 14.11(without voltage)to 20.12,9.82,11.15,and 15.97(with voltage)respectively.