PRETREATMENT OF A TITANIUM ELECTRODE FOR REDUCTION OF URANIUM(VI) IN NITRIC ACID-HYDRAZINE MEDIA

The oxide film at the surface of a titanium electrode, which was obser ved by an Electron Probe Microanalyzer (EPMA) measurement, was found t o hinder an electrolytic reduction of U(VI) to U(IV) in a nitric acid solution containing hydrazine. A method for the pretreatment of the ti tanium electrode to obtain a clear voltammogram for the reduction of U (VI) was investigated, and it was found that a controlled-potential el ectrolysis with a potential less than -0.8 V vs. SSE for about 30 min was adequate to remove the oxide film. The effect of the composition o f the HNO3+N2H5+ solution on the degree of pretreatment was examined. Voltammograms for the reduction of U(VI) at the oxide-free titanium el ectrode were recorded and analyzed.