ELECTROCHEMICAL OXIDATION OF OXALATE IN ALKALINE-SOLUTIONS

Experimental results show that the electrochemical oxidation of oxalat e in alkaline solutions at lead dioxide anodes can be achieved at cond itions of much higher alkalinity than previously reported in the liter ature using other types of electrodes. The oxalate in solutions contai ning 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 ap proximately 0.1 mol/L NaOH at 70-degrees-C by using lead dioxide anode s doped with silver and tin. The addition of small amounts of silver a nd tin (e.g., 0.06 % by weight) to lead dioxide films significantly in creases the oxalate oxidation currents and current efficiencies. These metals can be incorporated into the lead dioxide films by in situ oxi dation of lead-silver-tin alloys. Although oxalate could not be electr ochemically oxidized using lead dioxide electrodes at extremely high p H's (greater than approximately 14), reduction of the oxalate concentr ation to less than about 0.04 mol/L could be achieved at greater than 50% current efficiency at pH's up to about 13.