Electrochemical Properties of Uranium on the Liquid Gallium Electrode in LiCl-KCl Eutectic

Abstract

This work presents a study of electrochemistry of uranium on a liquid gallium in LiCl-KCl eutectic by applying a series of electrochemical techniques. The electrochemical window of the Ga electrode in LiCl-KCl eutectic is about −1.40 to −0.35 V vs. Ag/AgCl. The reduction of U(III) on liquid gallium starts at −0.86 V and is a one step process with the transfer of three electrons. The co-reductive cyclic voltammograms of U(III) and Ga(III) present a couple of sharp redox peaks at about −0.95 and −0.84 V, corresponding to the formation and dissolution of the intermetallic compound UGa3. In addition, the reduction of Ga(III) in LiCl-KCl melt is a two-step process: Ga(III) → Ga(I) → Ga. The activity coefficient and solubility of U in liquid Ga at the temperature range from 673 to 823 K were determined by coulometric titration and open circuit potential respectively. The Gibbs free energy for the formation of UGa3 was also calculated. The intermetallic compound UGa3 was deposited by potentiostatic electrolysis at −1.0 V in the LiCl-KCl -GaCl3-UCl3 and LiCl-KCl-UCl3 melt on solid W and liquid Ga electrodes at 773 K, respectively. The electrolysis efficiency is about 97% based on the ICP result. Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray diffraction (XRD) characterizations further identified the formation of UGa3.

Electrochemical Synthesis and Thermodynamic Properties of Pr‐Ni Intermetallic Compounds in a LiCl‐KCl‐NiCl2‐PrCl3 Melt

“…Due to the nucleation overpotential, open circuit chronopotentiometry as an appropriate electrochemical technique was employed to investigate the equilibrium potential of the system and to ensure the formation of the maximum number of Pr−Ni intermetallic compounds ,. In this way, a thin alloy layer specimen of Ni and Pr was obtained by potentiostatic electrolysis on a W electrode at a constant temperature.…”

Electrode reaction of Pr on Sn electrode and its electrochemical recovery fromLiCl‐KClmolten salt

“…where R ct represents charge transfer resistance; R, T, n, F, and j 0 have been explained above, separately. However, Equation ( 13) can be expressed as Equation (16) in the large overpotential (jηj > 100 mV).…”

“…6 The recovery of actinide elements by partitioning and transmutation, considered as one of the promising options for spent fuel management, can make full use of nuclear fuel and minimize nuclear wastes, 7 which is conducive to increase the utilization rate of nuclear energy. [8][9][10][11][12][13] Since molten salt has some excellent characteristics, 14,15 for instance, radiation resistance, short cooling time, and antiproliferative properties, pyrometallurgical technology, employing molten salt as medium, is considered as a promising method in the field of separation and extraction of actinides, 16,17 which mainly includes reduction extraction in molten saltliquid metal system, 18,19 electrorefining, 20,21 and electrochemical extraction using reactive cathodes. [22][23][24][25][26] Wherein, electrochemical extraction is the most extensive pyrochemical separation process.…”

Electrochemical properties of yttrium on W and Pb electrodes in LiCl–KCl eutectic melts

“…5). Based on eqn (8), the ECD for reaction (11) were estimated and found to be 12.6 to 18.9 mA cm À2 (shown in Table 3), which are greater than those on inert W electrode. In addition, the calculated activation energy is 26.21 kJ mol À1 , less than the one on W electrode, which indicates that the reaction on liquid Pb electrode need less energy and easily occurs on liquid Pb electrode.…”

“…For example, the electrode area is changeless, and the diffusion of deposited metal into the liquid metal is easier. 6,7 Thus, liquid Ga, [7][8][9][10][11] Bi, [12][13][14][15] Cd, 13,16 Zn, [17][18][19][20][21][22][23][24] Sn 25 were selected as cathode to separate REs from molten salts. The melting point of Pb metal is 600 K and boiling point is 1798 K, it is easy to melt but doesn't evaporate at 723-823 K. Thus, Pb metal seems to be a good candidate as the cathode material in separation and extraction of REs by molten salt electrolysis.…”