ABSTRAKT

This paper deals with examples of complications arising during the electrodeposition process in molten salts of multivalent elements such as uranium, niobium and hafnium. The electroreduction process of U(IV), Nb(V) and Hf(IV) includes the intermediate formation of U(III), Nb(IV) and Hf(II) respectively, giving rise to secondary reactions such as disproportionation and adsorption. Each reaction of the overall process is characterized by using electrochemical criteria provided by chronopotentiometric and voltammetric measurements. Prereduction of U(IV) or addition of fluoride ions in the electrodeposition bath of hafnium have minimized the troubles due to these reactions.