Electrochemical extraction of Pr on reactive Ga, Ga–Pb and Pb electrodes in molten NaCl–2CsCl eutectic

Abstract

The electrochemical behavior of Pr(III) ions in molten NaCl–2CsCl solutions was investigated via different electrochemical techniques on Mo inert and Ga, Ga–Pb and Pb reactive electrodes. It was determined that the electrochemical reduction process on inert electrodes proceeds in one stage. It is reversible at low scan rates below 0.1 V/s, whereas it is irreversible at high scan rates. The diffusion coefficients of PrCl63- complex ions were determined at different temperatures, and the activation energy of this process was calculated as 42.2 kJ mol−1. The co-reduction of Pr(III), Ga(III) and Pb(II) ions was investigated, and the redox potentials of forming different alloys were determined. The electrodeposition of Pr(III) ions was studied on three reactive electrodes, and one-step electrode processes were determined. The current exchange density of Pr(III) ions increased in the order of Pb < Ga–Pb < Ga. The composition of Ga2Pr and Pb3Pr intermetallic compounds was formed on reactive electrodes and their specific thermodynamic characteristics were calculated. Finally, praseodymium was successfully extracted from the molten salt in the form of Ga2Pr and Pb3Pr intermetallic compounds on three liquid reactive electrodes via potentiostatic electrolysis.