Liquid Bi electrode-assisted selective separation of UO22+ and Ce(III) in molten salt

Studied the electrochemical behavior of Ce(III) ions on Bi film electrodes and liquid Bi electrode. • Studied the effect of Ce (III) ions on the electrochemical behavior of UO 2 2+ at Bi film electrode and liquid Bi electrode. • Ce(III) ions and UO 2 2+ ions were separated via potentiostatic and galvanostatic electro-deposition on a liquid Bi electrode. • Found that better separation of Ce(III) ions and UO 2 2+ can be achieved at relatively low potentials. • The extraction efficiency and separation efficiency were calculated for electrolytic separation at lower potentials. To achieve the separation of uranium and fission products, a liquid Bi electrode was employed to study the electrochemical separation of the fission product Ce(III) ions and UO 2 2+ ions. The electrochemical reduction mechanism of Ce(III) ions was investigated at a Bi film electrode using three electrochemical testing methods: CV, SWV and CP, The results showed that a series of reduction peaks related to the formation of Ce-Bi intermetallic compounds appeared at potentials more positive than the reduction potential of Ce(III) ions. Meanwhile, the electro-reduction mechanism of Ce(III) ions at a liquid Bi electrode was also explored. A reduction peak associated with the formation of Bi-Ce solid solution was recorded. The impacts of Ce(III) ions on the electro-reduction mechanism of UO 2 2+ at a Bi film electrode were examined, and found that the electro-reduction of UO 2 2+ was two-step single-electron transfer process before and after the addition of Ce(III) ions. Furthermore, electrochemical separation of UO 2 2+ and Ce(III) ions was performed at a liquid Bi electrode at -0.7 V/-1.3 mA cm -2 . XRD results confirmed that the separation product included not only UO 2 , but also Ce 2 O 3 and Bi-Ce alloy. Nevertheless, constant potential electrolysis experiment was conducted at the potential of -0.3 V, and the product analyzed by XRD, SEM and EDS demonstrated that only spherical UO 2 with a regular morphology was obtained. The separation factor between UO 2 2+ and Ce(III) ions and extraction efficiency of UO 2 were calculated to be 34.4 and 97.76 %, respectively. Download: Download high-res image (184KB) Download: Download full-size image