Electrochemical treatment and reuse of nickel plating rinse waters

The treatment and disposal of nickel-contaminated rinse waters places an additional cost-burden on a metal plating facility. Increasing the resource productivity within an electrolytic nickel plating process by creating a recycle loop for the "waste" components of the rinse water can reduce disposal and raw material costs. In this study, an electrowinning cell, fitted with an anion exchange membrane, was used to recover valuable components from a simulated electrolytic nickel plating rinse water by a combination of electrodeposition and electrodialysis. The anion exchange membrane in the cell permitted a dual electrode function. Nickel metal was recovered from the rinse water at the cathode and a sulfuric/hydrochloric acid mixture was generated at the anode (which can be used in the pickling baths to clean metal parts). The boric acid in the rinse water could not be recovered by anion exchange due to its high acid dissociation constant. The cell worked effectively in both a batch and a continuous feed mode. The research demonstrated that this type of electrochemical cell could feasibly replace the traditional ion exchange process for treating rinse waters, and eliminate regeneration chemicals/waste while producing useful process materials.