Electrochemical Behaviour of Pu3+ on Active Al Cathode in LiCl-KCl Molten Salt

Abstract

The electrolytic separation of actinides(An) from fission products(FPs) on solid Al cathode is one of the most promising pyrochemical reprocessing processes. In this work, the electrochemical behaviour of Pu3+ on active Al solid cathode was studied through the transient electrochemical method. Based on the results of cyclic voltammetry(CV) and square wave voltammetry(SWV), Pu3+ can be reduced into alloy through a onestep threeelectrons transfer process on Al cathode, and the reaction is irreversible. The relationship between the reduction potential of the alloy formed by Pu3+ with Al and temperature is EΘ,*(Pu3+/PuAln)(vs. Cl-/Cl2)=-2.944+9.84×10-4T. Five Pu alloys(involving Pu3Al, PuAl, PuAl2, PuAl3, and PuAl4) are formed according to the results of open circuit chronopotentiometry(OCP) together with phase diagrams of Pu-Al. Furthermore, the formation Gibbs free energies of PuAl4 at different temperature are calculated.

Keywords

• licl-kcl molten salt
• plutonium
• electrochemical behavior
• al cathode