Quantitative analysis of Eu2+ and Eu3+ in LiCl–KCl eutectic melt by spectrophotometry and electrochemistry

Kim, Tack-Jin; Uehara, Akihiro; Nagai, Takayuki; Fujii, Toshiyuki; Yamana, Hideaki

doi:10.1016/j.jnucmat.2010.12.004

Cited by 33 publications

(28 citation statements)

References 27 publications

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“…In a recent report about the EuCl 3 system using the 3 LiCl -2 KCl eutectic melt at 773 K, it has been noted by Kim and coworkers, that both the Eu 3+ and Eu 2+ species exist in equilibrium. 38 However, we saw no evidence, in growth of the 325 nm absorbance peak characteristic of the presence of Eu 2+ , of the spontaneous equilibrium between Eu and Eu 2+ under the temperature and eutectic salt conditions used in our work.…”

Section: -37contrasting

confidence: 62%

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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Section: -37contrasting

confidence: 62%

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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“…Although most lanthanides exist in the trivalent oxidation state in molten salts, europium has been identified to be present as the mixed valence states of Eu(II) and Eu(III) [38,60,61]. Eu(III) is likely to become a divalent state in molten LiCl-KCl salt.…”

Section: Europiummentioning

confidence: 99%

Optical absorption and fluorescence properties of trivalent lanthanide chlorides in high temperature molten LiCl–KCl eutectic

Kim

Yun

2016

Journal of Luminescence

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“…The combination of electrochemical and spectroscopic methods may provide advantages over pure electrochemical approaches, including unambiguous speciation even under dilute conditions [7,20,25,26]. Figure 4a shows the absorption spectra measured during the consecutive addition of the Np-LiCl-KCl cylinders in a LiCl-KCl eutectic melt at 450°C, and the concentration of neptunium increases accordingly from 0.41 to 1.2 mM.…”

Section: Spectroelectrochemical Study Of Npclmentioning

confidence: 99%

Electrochemical preparation and spectroelectrochemical study of neptunium chloride complexes in LiCl–KCl eutectic melts

Kim¹,

Park

Bae

et al. 2015

J Radioanal Nucl Chem

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We prepared neptunium chloride complexes electrochemically and performed spectroelectrochemical measurements of neptunium ions in LiCl-KCl eutectic melts at 450°C, where the neptunium concentrations studied were in the range of 0.1-1 mM. We observed a highly absorbing f-d transition band of Np 3? at 383 nm, which was used to determine an formal potential of the Np 4? |Np 3? redox couple (E°0 = 0.45 V vs. Ag|Ag ? ) with a solution of concentration as low as *0.1 mM. This result agreed well with the value (E°0 = 0.42 V vs. Ag|Ag ? ) determined by cyclic voltammetry with a *15 mM solution.

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Quantitative analysis of Eu2+ and Eu3+ in LiCl–KCl eutectic melt by spectrophotometry and electrochemistry

Cited by 33 publications

References 27 publications

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

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

Optical absorption and fluorescence properties of trivalent lanthanide chlorides in high temperature molten LiCl–KCl eutectic

Electrochemical preparation and spectroelectrochemical study of neptunium chloride complexes in LiCl–KCl eutectic melts

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