Kinetics of oxidation of pentavalent neptunium by pentavalent vanadium in solutions of nitric acid

The behaviors of reduction of NpO2 by controlled potential electrolysis were studied, and a unique time course of electrolysis current was observed. It was concluded that NpO2 was reduced by two reduction processes, which were the chemical reaction with Np and the electrocatalytic reduction by adsorbed hydrogen atom on platinum electrode surface. The time courses of current for controlled potential electrolysis of NpO2 under various conditions of the solution were investigated, and the effects of the concentration of H and NO3 on electrolysis behavior were explained by proposed reduction mechanisms. The Np was prepared from NpO2 in 3 mol dm HNO3 by electrolytic reduction at the potential where evolution of hydrogen gas and reduction of NO3 were inhibited. The electrolysis efficiency could be improved.