Electrochemical Behaviour of Uranium

The electrolysis of solutions containing uranium compounds has not been fully investigated, but in general the product at the cathode appears to consist of hydrated oxides in various stages of oxidation. This is the case even when a diaphragm is used. The metal itself is not deposited under ordinary conditions. According to Pierle, on electrolysing aqueous solutions of uranyl salts with low-current density, the first product is hydrated uranic oxide, UO₃.H₂O, which gradually changes, as electrolysis proceeds, to a black oxide of varying composition. With higher current density, uranyl sulphate is reduced to uranous sulphate, and if the solution is neutral or alkaline, a mixture of black and yellow oxides is deposited; in acid solution, only a slight deposit, metallic in appearance, is obtained. A concentrated solution of uranyl nitrate gives a black pyrophoric substance of undetermined composition, which, when dried and heated, yields a product of composition U₂O₅. When uranous salts are electrolysed, a black deposit, of composition U₃O₁₀.2H₂O, is obtained at the cathode.

The method of electrolysis has been suggested as a means of separating uranium from solutions of uranyl salts, the hydrated oxide deposited being converted by heat to the oxide, U₃O₈.

The electrolysis of uranium compounds in organic solvents has been investigated.

Uranyl salts in solution undergo hydrolysis, and the electrical conductivity of such solutions increases with time. The difference between Λ₃₂ and Λ₁₀₂₄ for many of the salts is abnormally high, probably because the dissociation takes place in stages.