Electrochemical behavior and electronic absorption spectra of uranium trivalent ions in molten LiCl–CsCl mixtures

Nagai, Takayuki; Uehara, Akihiro; Fujii, Toshiyuki; Sato, Nobuaki; Yamana, Hideaki

doi:10.1016/j.jnucmat.2011.03.048

Cited by 13 publications

(12 citation statements)

References 21 publications

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“…Also, because the research has been done by a variety of groups, the experimental conditions are not the same, and therefore data cannot be easily compared to determine the effect of the melt composition. There are a few publications that do compare properties between various molten salt eutectic melts using cyclic voltammetry or square wave voltammetry, but they have not used electrochemistry in conjunction with spectroscopic measurements ,,,,.…”

Section: Introductionmentioning

confidence: 99%

“…This additional selectivity comes from the spectroscopic change that is often associated with a change in oxidation state that occurs in the electrochemical window of interest ,. Most of the research that involves spectroelectrochemistry on actinides and lanthanides in molten salts has been performed on U ,, Np ,, Pu and Eu ,; it has also been used to monitor the formation of oxychloride species . Spectroelectrochemistry is also capable of determining the diffusion coefficients of species in solution by monitoring the absorbance change over time during electrolysis.…”

Section: Introductionmentioning

confidence: 99%

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Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

et al. 2016

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Key electrochemical properties affecting pyroprocessing of nuclear fuel were examined in four eutectic melts using Eu3+/2+ as a representative probe. We report the electrochemical and spectroelectrochemical behavior of EuCl3 in four molten salt eutectics (3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl and 3 LiCl−2 CsCl) at 873 K. Cyclic voltammetry was used to determine the reduction potential for Eu3+/2+ and the applied potentials for spectroelectrochemistry. Single step chronoabsorptometry and thin‐layer spectroelectrochemistry were used to obtain the number of electrons transferred, reduction potentials and diffusion coefficients for Eu3+ in each eutectic melt. The reduction potentials determined by thin‐layer spectroelectrochemistry were essentially the same as those obtained using cyclic voltammetry. The diffusion coefficient for Eu3+ was the largest in the 3 LiCl−NaCl melt, showed a negative shift in the 3 LiCl−2 KCl melt, and was the smallest in the LiCl−RbCl and 3 LiCl−2 CsCl eutectic melts. The basic one‐electron reversible electron transfer for Eu3+/2+ was not affected by melt composition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

et al. 2016

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“…22,23 A few investigations have also looked into the effects of changing the eutectic melt composition on the redox potential of some lanthanides such as Sm 3+/2+ , 13,17 Eu 3+/2+ , 13,14,17,19 Tm 3+/2+ , 24 and Yb 3+/2+ , 24,25 as well as the actinides Cm 3+/026 and U 3+/0 . 27,28 However, each study has used a different experimental design with varying temperatures and electrochemical techniques so the results cannot be easily compared.…”

mentioning

confidence: 99%

Electrochemistry of Europium(III) Chloride in 3 LiCl – NaCl, 3 LiCl – 2 KCl, LiCl – RbCl, and 3 LiCl – 2 CsCl Eutectics at Various Temperatures

Schroll

Chatterjee

Levitskaia

et al. 2017

J. Electrochem. Soc.

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Here we report the effect of changing the eutectic melt composition on the electrochemical properties of europium(III) chloride under pyroprocessing conditions. Stoichiometry of electron-transfer, redox potentials and diffusion coefficients were determined using various electrochemical and spectroelectrochemical techniques in four different eutectic mixtures (3 LiCl -NaCl, 3 LiCl -2 KCl, LiCl -RbCl, and 3 LiCl -2 CsCl) while varying the temperature of the melt. It was determined that Eu 3+ undergoes a one electron reduction to Eu 2+ in each melt at all temperatures evaluated. Within each of the melts a positive shift in the redox potential as well as an increase in the diffusion coefficient for Eu 3+ was observed as the temperature increased. Also observed was a positive shift in the redox potential and increase in the diffusion coefficient for Eu 3+ as the weighted average of the cationic radii the melt composition decreased. Pyroprocessing is one of the newest techniques for spent nuclear fuel reprocessing in which the separation is accomplished electrochemically in molten salt media at temperatures of >500• C. 1-3 Some of the advantages of pyroprocessing over the more traditional liquidliquid extraction techniques are that there is no organic solvent that is susceptible to radiolysis, 4,5 lack of pure plutonium product which provides less likelihood for proliferation, 6 generation of the U-Pu alloy product is ready for immediate fabrication into new fuel rods 7 and the ability to do a group separation of all actinides.8 There are also engineering related advantages such as amenability to scaling to the needs of the facility 9 and making the refinement vessel more compact. 10,11The most important information needed to understand pyroprocessing is accurate thermodynamic data for each of the analytes that may be found in used nuclear fuel in each of the possible eutectic melt compositions. We have chosen to investigate europium(III) chloride because it is a non-radioactive analog to the actinides which makes it safer to work with, it has the least negative redox potential of the lanthanides, and it undergoes a change in its absorption spectrum when it is reduced from Eu 3+ to Eu 2+ . 12 Prior research has been performed using europium(III) chloride and evaluating its thermodynamic properties in different melts, such as LiCl, 13 In this work we systematically evaluated the redox potentials and diffusion coefficients for europium(III) chloride using differential pulse voltammetry and cyclic voltammetry in three different eutectic salt compositions over a range of temperatures. The experiments were performed from 673 K to 1173 K in 3 LiCl -NaCl, LiCl -RbCl and 3 LiCl -2 CsCl. This data along with the results from our previous * Electrochemical Society Member.z E-mail: heinemwr@ucmail.uc.edu; sam.bryan@pnl.gov reports (Electrochemistry of Europium in 3 LiCl -2 KCl from 643 to 1123 K 29 and Spectroelectrochemistry of Europium in 3 LiCl -NaCl, 3 LiCl -2 KCl, LiCl -RbCl, and 3 LiCl −2 CsCl at 873 K 30 ) were analyzed ...

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“…[3][4][5] The viscosity is also related to the electrical properties and the structure of the liquids. 5,6 However, there are only viscosity data of pure molten LiCl-KCl eutectic in a limited range of temperatures (890-1080 K). 7,8 Therefore, interpolation and extrapolation are required to determine the viscosity at a specific process condition, for example, at ca.…”

mentioning

confidence: 99%

High-Temperature Viscosity Measurement of LiCl-KCl Molten Salts Comprising Actinides and Lanthanides

Kim¹,

Bae²,

Kim³

et al. 2012

Bulletin of the Korean Chemical Society

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Electrochemical behavior and electronic absorption spectra of uranium trivalent ions in molten LiCl–CsCl mixtures

Cited by 13 publications

References 21 publications

Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

Electrochemistry of Europium(III) Chloride in 3 LiCl – NaCl, 3 LiCl – 2 KCl, LiCl – RbCl, and 3 LiCl – 2 CsCl Eutectics at Various Temperatures

High-Temperature Viscosity Measurement of LiCl-KCl Molten Salts Comprising Actinides and Lanthanides

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Electrochemical behavior and electronic absorption spectra of uranium trivalent ions in molten LiCl–CsCl mixtures

Cited by 13 publications

References 21 publications

Spectroelectrochemistry of EuCl3 in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

Spectroelectrochemistry of EuCl3 in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

Electrochemistry of Europium(III) Chloride in 3 LiCl – NaCl, 3 LiCl – 2 KCl, LiCl – RbCl, and 3 LiCl – 2 CsCl Eutectics at Various Temperatures

High-Temperature Viscosity Measurement of LiCl-KCl Molten Salts Comprising Actinides and Lanthanides

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Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K

Spectroelectrochemistry of EuCl₃ in Four Molten Salt Eutectics; 3 LiCl−NaCl, 3 LiCl−2 KCl, LiCl−RbCl, and 3 LiCl−2 CsCl; at 873 K