Feasibility studies on electrochemical recovery of uranium from solid wastes contaminated with uranium using 1-butyl-3-methylimidazorium chloride as an electrolyte

In order to examine feasibility of the electrochemical deposition method for recovering uranium from the solid wastes contaminated with uranium using ionic liquid as electrolyte, we have studied the electrochemical behavior of each solution prepared by soaking the spent NaF adsorbents and the steel waste contaminated with uranium in BMICI (1-butyl-3-methyl- imidazolium chloride). The uranyl(VI) species in BMICI solutions were found to be reduced to U(V) irreversibly around -0.8 to -1.3 V vs. Ag/AgCl. The resulting U(V) species is followed by disproportionation to U(VI) and U(IV). Based on the electrochemical data, we have performed potential controlled electrolysis of each solution prepared by soaking the spent NaF adsorbents and steel wastes in BMICI at -1.5 V vs. Ag/AgCl. Black deposit was obtained, and their composition analyses suggest that the deposit is the mixtures of U(IV) and U(VI) compounds containing O, F, Cl, and N elements. From the present study, it is expected that the solid wastes contaminated with uranium can be decontaminated by treating them in BMICI and the dissolved uranium species are recovered electrolytically. (C) 2015 Elsevier B.V. All rights reserved.