通过络合方法强化电渗析对二价同电荷重金属离子分离效果的初步研究

对二价过渡金属离子选择适当的配位体以形成不同的络合物,通过改变电荷,离子在膜内的淌度此及分配系数,或络合物的稳定常数的差异来达到同电荷离子彼此分离的目的。研究结果表明,对形成铜氨络离子—镁离子溶液体系和铜乙二胺络离子—镁离子溶液体系,采用常规电渗析方法进行分离,其T_(Mg)~(Cu)值较常规溶液体系分别提高近一倍和25%;对铜—镁混合溶液和钴—镍混合溶液采用EDTA 络合剂和特殊电渗析工艺,可使T_(Mg)~(Cu)→0或T_(Nl)~(Co)→∞,达到完全分离。本研究开发的分离同电荷离子的电渗析新工艺,对于开拓电渗析技术的新应用领域具有一定的指导意义。

THE STUDY OF COMPLEXING EFFECT ON SEPARATING SAME CHARGED HEAVY METAL CATIONS BY ELECTRODIALYSIS

A study has been carried out in order to improve the separating effici- ency of same charged ions.In the experiments,complexing agent suitable for bivalent heavy metal cations was added into the solution to be separated by electrodialysis to form complex ions.In this way,the ionic charge,ionic mobility ratio and/or their distribution coefficient in the membrane were changed obviously. The experimental results show that for Cu~(2+)-Mg~(2+) solution,its T_(Mg)~(Cu) is increased to 1.8 and 1.2 respectively as compared with common solution without complex additives by traditional electrodialysis because a complex- ing agent is added to the solution to form Cu(NH_3)_4~(2+)-Mg~(2+) and EnCu~(2+)- Mg~(2+).In addition,for Cu~(2+)-Mg~(2+) or Co~(2+)-Ni~(2+) solution a complete separation can be reached with EDTA addition and by means of particular electrodia- lysis technology with proper membrane arrangement.