Electrochemical reduction of nickel ions from dilute artificial solutions in a GBC reactor

The electrochemical reduction of nickel ions from a dilute solution has been carried out in a ‘gas diffusion electrode packed bed electrode cell’ (GBC). Particle size and electrode configuration have been found to have a significant influence on the reduction process. Electrodes with a high porosity and large pores have been found to be the best for nickel deposition. The nickel current efficiency, ηNi, is reported to be dependent on the current density, volumetric flow rate, nickel and boric acid concentration, and the pH. The fall in the nickel current efficiency is caused by an increase in electrode surface pH above a certain level, caused by either high bulk solution pH or high current density, leading to possibly formation of Ni(OH)2. It has been found that under conditions of exclusively metallic nickel deposition ηNi/(1−ηNi) is proportional to i0.69,Q10.52,CNi0.67,CBA−0.19 and pH1.0.