Electrolytic recovery of gallium from dilute solutions employing microelectrodes

The recovery of Ga from dilute solutions is known to be slow and inefficient due to competing hydrogen evolution and the limitations of mass transport. Methods used to improve the process include pulse plating, inhibition of H evolution by suitable additives, increasing the p H, and conducting the process at temp. above the melting point of Ga. An alternative approach was taken employing microelectrodes to enhance the rate of mass transport and thus to increase the rate of Ga recovery. Potentiostatic plating and stripping experiments were performed using electrodes ranging in dia. from 1 cm down to 45 mu m. The effect of electrode dia. on the rate and efficiency of the plating of Ga was studied at different potentials and under different conditions of mass transport. The effect of plating time was also determined, and the conditions for the optimum recovery of Ga in terms of the overall rate and the current efficiency were evaluated. Carbon fiber epoxy composites can serve as ensembles of microelectrodes. It was shown that, with a typical radius of 3-5 mu m for the individual fibers, considerable enhancement of the rate of recovery of metals from dilute solutions can be expected. 29 ref.--AA