Photoelectrochemical cell for the combined photocatalytic oxidation of organic pollutants and the recovery of metals from waste waters

Photoanodes were prepared by immobilising TiO2 powder on the surface of Ti–6Al–4V alloy. The TiO2 electrode was incorporated into the anode compartment of a two compartment photoelectrochemical cell and short circuited to a copper wire counter electrode in the cathode compartment. The anode compartment contained oxalate solution and the cathode compartment contained copper sulphate solution. On illumination of the TiO2 anode oxalate was photooxidised at the surface of the TiO2 and the photogenerated electrons moved via the external circuit to the counter electrode where copper ions were reduced. The total charge passed during the experiments was consistent with the amount of copper plated out at the counter electrode. Ninety-seven per cent of the copper in solution was recovered after 120 min of irradiation under unoptimised conditions.