Lectrochemical oxidation of oxalate in alkaline solutions

Experimental results show that the electrochemical oxidation of oxalate in alkaline solutions at lead dioxide anodes can be achieved at conditions of much higher alkalinity than previously reported in the literature using other types of electrodes. The oxalate in solutions containing 0.05 mol/L approximately 0.1 mol/L sodium oxalate was anodically oxidized to carbonate with high efficiency in the presence of up to approximately 0.1 mol/L NaOH at 70-degrees-C by using lead dioxide anodes doped with silver and tin. The addition of small amounts of silver and tin (e.g., 0.06 % by weight) to lead dioxide films significantly increases the oxalate oxidation currents and current efficiencies. These metals can be incorporated into the lead dioxide films by in situ oxidation of lead-silver-tin alloys. Although oxalate could not be electrochemically oxidized using lead dioxide electrodes at extremely high pH's (greater than approximately 14), reduction of the oxalate concentration to less than about 0.04 mol/L could be achieved at greater than 50% current efficiency at pH's up to about 13.