Recovery of spent electroless nickel plating bath by electrodialysis

Recovery of spent electroless nickel plating (EN) bath decreases the drainage of waste water and saves resources. During the treatment of spent EN bath by electrodialysis, the removals of harmful components, such as phosphite, sulfate and sodium ions, were significant, meanwhile the reduction rates of useful components, for example, hypophosphite and nickel ions, were slow, which was beneficial to the regeneration of spent EN bath. The process was characterized in terms of limiting current density, membrane fouling, removal of main components, and current efficiency. The correlation between working current, concentration changes and run time was discussed. Using actual spent EN bath the fouling behavior of the membranes was investigated in long-term experiments. (C) 1999 Elsevier Science B.V. All rights reserved.