Influence of Fluoride Ions on the Speciation and Electrochemical Behavior of Th(IV) in Molten LiCl-KCl with a Copper Electrode

The speciation and electrochemical behavior of thorium (IV) fluoride in molten LiCl-KCl with a copper working electrode was investigated. In addition to the reduction of Th(IV) [ThCl62- and ThCl73-] to metallic thorium, there is a minor peak in the cyclic and square wave voltammagrams that results from the reduction of Th(IV) [ThCl6-xFx2- and ThCl7-xFx3-] to metallic thorium on the basis of the square wave voltammetry and X-ray diffraction results. This is also supported by the formation of metallic thorium deposits upon potentiostatic electrolysis. In addition, the diffusion coefficient and diffusion activation energy of Th(IV) with a copper electrode was determined, which show similarity in comparison to those obtained using inert working electrodes.