Electrodialysis enhanced with disodium EDTA as an innovative method for separating Cu(II) ions from zinc salts in wastewater

Abstract

In recent years, interest in developing methods for hazardous metal recovery from wastewater has grown steadily within the scientific community. This report describes a method based on electrodialysis enhanced with metal-complex formation to separate cupric ions from zinc sulfate present in a model zinc plating bath. The investigated method can be applied for resource (zinc sulfate) recovery, or to reduce the amount of hazardous galvanic wastes. In this work, the disodium salt of ethylenediaminetetraacetic acid (Na2EDTA) is employed as a complexing agent. The effects of the membrane and current density on the separation efficiency are evaluated and discussed. Finally, the optimal conditions for selective removal of Cu(II) ions from a zinc salt bath are identified, and the effectiveness of the examined method is demonstrated in a batch test. It was determined that, by using thick heterogeneous AM(H)-CM(H) ion-exchange membranes an approximately 13-fold reduction in Cu(II) content, relative to Zn(II), can be achieved at high Zn(II) recovery (94.6%) and current density (220 A/m2). The possibility of applying the described method for concentration of zinc salts in the plating bath was also evaluated. It was shown that Zn(II) content can be increased of up to 1.5 times.