Electro-catalytic oxidation of artificial human urine by using BDD and IrO2 electrodes

Galvanostatic anodic oxidation of artificial human urine (AHU) was carried out by using boron doped diamond (BDD) and IrO 2 electrodes respectively. It was found that organic compounds in urine could be almost completely mineralized in a few hours and ammonia may be oxidized into N 2 by the electro-catalytic process. However, the oxidation processes were highly dependent on the electrode materials. On the non-active BDD electrode complete oxidation occurred, and the final oxidation products of inorganic ions, including ClO 4 − and NO 3 − , were formed. Whereas on the active IrO 2 electrode, the final products generated and left in solution were highly toxic substances, including N 2 H 4 and NO 2 − , because the oxidizing activity on the IrO 2 electrode surface is relatively low. The pH values during the degradation process were monitored and the corresponding degradation mechanisms and pathways on both electrodes are proposed based upon the measured inorganic intermediates.