Reclaim nickel and remove organics from the spent electroless nickel-plating bath by electrolysis

Typical wastes from nickel plating operations include excess drag-out solution. An electrochemical approach was made to recover the nickel and remove the organic pollutants from the spent electroless nickel-plating bath. An electrolyte cell which was constructed by the cathode of porous nickel foam and the anode of Ti/RuO2 was used. During electrolysis, the nickel ion was electrodeposited at the cathode and the oxidation of the organics in the bath was conducted at the anode. The current (i), time (t), temperature (T) and pH of the solution affected the recovery efficiency of nickel with constant potential electrolysis. With the optimum experimental conditions of pH = 7.6, i = 0.45 A, T = 65°C and t = 2 h, the concentration of nickel ion was reduced from 2.09 g/L to 0.053 g/L and the recovery rate of nickel, the current efficiency and the consumed energy were 97.5%, 17.1%, 12.2 kWh/kg Ni, respectively. Meanwhile, total organic carbon (TOC) of the bath was reduced from 5800 mg/L to 152.5 mg/L and the removal efficiency of TOC was 97.3%. The recovery rate of nickel could keep to about 97% when electrodeposit was used to recover nickel for 40 hours in a laboratory batch reactor containing the spent bath. Dull nickel containing phosphorus was obtained on the cathode.