Influence of anode material on electrochemical decomposition of urea

Voltammetric investigations into the process of anodic decomposition of urea using Ti/Pt, Ti/(Pt–Ir)70:30, Ti/RuO2, Ti/(RuO2–TiO2)40:60, Ti/(RuO2–TiO2–IrO2)20:60:20, Ti/(Ta2O5–IrO2)70:30 electrodes have been carried out. Two anodes namely (Ti/(Pt–Ir)70:30 and Ti/(Ta2O5–IrO2)70:30) were found to be stable enough and indicated the required activity to produce non-toxic N2 and CO2 in place of nitrites and nitrates, the commonly reported electrochemical urea oxidation products. The kinetics of the process in question using the above two electrodes was further examined in a periodic electrolyzer. The effect of the anodic current density (j = 2–10 A/dm2), initial urea concentration (c0M = 1–10 g/dm3) and the concentration of sodium chloride (cNaCl = 1–10 g/dm3) on basic process indices (average rate of urea decomposition, a; current efficiency, Wp, and unit DC power consumption, Zj) was discussed.