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

Abstract

The oxide film at the surface of a titanium electrode, which was observed by an Electron Probe Microanalyzer (EPMA) measurement, was found to hinder an electrolytic reduction of U(VI) to U(IV) in a nitric acid solution containing hydrazine. A method for the pretreatment of the titanium electrode to obtain a clear voltammogram for the reduction of U(VI) was investigated, and it was found that a controlled-potential electrolysis 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 of the HNO3+N2H5+ solution on the degree of pretreatment was examined. Voltammograms for the reduction of U(VI) at the oxide-free titanium electrode were recorded and analyzed.