Flow electrolysis of U, Np and Pu ions utilizing electrocatalysis at a column electrode with platinized glassy carbon fiber working electrode

Redox reactions of U, Np and Pu ions of various oxidation states were investigated by flow electrolysis at a column electrode (CE) equipped with a platinized glassy carbon (GC) fiber working electrode (Pt/GC-WE), and compared with those observed at the CE with an ordinary activated GC fiber working electrode (GCact-WE). Since the overpotential for the reduction of NpO2+ and PuO2+ were decreased when Pt/GC-WE was employed, the one-electron reduction of NpO2+ to Np4+ followed by that of Np4+ to Np3+ and the one-step three-electron reduction of PuO22+ to Pu3+ proceeded at the CE with Pt/GC-WE, different from the reduction processes of NpO2+ and PuO22+ at the CE with GCact-WE. On the other hand, the redox reactions of UO22+/U4+, Np4+/Np3+, NpO22+/NpO2+ and Pu4+/Pu3+ were scarcely affected with the platinization of the GC working electrode. The reaction processes observed at the CE with Pt/GC-WE were elucidated consulting with those at the CE with GCact-WE and voltammograms at rotating platinum, platinized platinum, GC and platinized GC electrodes. A rapid and precise method for the preparation of U, Np and Pu ion of a desired oxidation state was proposed by taking advantage of the unique characteristics of the CE with Pt/GC-WE.