Electrorecovery of Actinides at Room Temperature

Abstract

The electrochemical behavior of U(IV) and U(III) species in room temperature ionic liquids (RTILs) and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we have focused on thus far are based on 1,3-dialkylimidazolium or quaternary ammonium cations and -N(SO2CF3)2 anions. Our results from XPS studies of electrooxidized uranium metal surfaces indicate that uranium metal reacts with the anion from the RTIL, most likely through an initial fluoride abstraction, forming decomposition products that inhibit the bulk electrodeposition of uranium metal. Similar results were found when the organic solvents were used with TBA[B(C6F5)4] as the supporting electrolyte, although the voltammetric data of uranium ions in these solutions is more encouraging in relation to electrodeposition of uranium metal. Preliminary results on the voltammetric behavior and bulk electrodeposition of plutonium species are also presented.