Photocatalytic Conversion of Am(III) to Am(VI) Using a TiO2Electrode

Abstract

Titanium-titania (Ti|TiO2) nanostructured electrodes in 0.1 M HNO3 solutions under UV-light illumination using a 375 nm LED and a 1.55 V vs SCE bias photoelectrochemically oxidize Am(III) to Am(VI) (AmVIO22+). Oxidation occurs through photoelectrochemically generated adsorbed hydroxyl radicals (2.81 V vs SCE) and/or direct electron transfer between the excited-state electrode (E(TiO2VB*) = ca. 2.95 V vs SCE) and Am(III) (E(AmIV/III) = 2.62 V). An electrochemically irreversible but chemically reversible electrochemical process at 1.60 V vs SCE is assigned to the one-electron Am(VI/V) couple. This system may be applied to used nuclear fuel reprocessing to separate actinides of concern (U, Np, Pu, and Am), where Am is the most significant challenge.