Oxide ion electrodes and oxide ion donors in molten alkaline halogenides. A consideration of potentiometric studies

Cherginets, V.L.

doi:10.1016/s0013-4686(96)00308-8

Cited by 28 publications

(23 citation statements)

References 35 publications

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“…It is obvious that the same concentration of ÔfreeÕ O 2À in Li-based melts may be achieved at considerably higher concentrations of a strong Lux base, than, e.g., in the {CsCl + KCl + NaCl} eutectic. The observed shift of the inflection point in acidic melts proves the above-considered mechanism [13]. The calibration data at T ¼ 973 K and T ¼ 1073 K are similar and further discussion is not needed.…”

Section: Calibration Of E Vs Po Plotssupporting

confidence: 68%

“…In the case of {KCl + LiCl} the inflection takes place at pO % 2 as shown in figure 1. The appearance of the second section in E-pO plots is caused by formation of peroxide ions on or near the electrode surface owing to the interaction of excess of O 2À with gaseous oxygen [13] …”

Section: Calibration Of E Vs Po Plotsmentioning

confidence: 99%

“…Coefficients of equation(13) at temperatures T , for the {KCl + LiCl} eutectic ciation can be studied immediately, using the solution after the last addition of KOH.Keeping the melt under CO 2 flow results in sharp reduction of concentration of O 2À that causes an e.m.f. rise (the up arrow in…”

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confidence: 99%

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Potentiometric study of acid–base equilibria in the {KCl+LiCl} eutectic melt at temperatures in the range (873 to 1073) K

Cherginets¹,

Demirskaya²,

Rebrova³

2004

The Journal of Chemical Thermodynamics

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Section: Calibration Of E Vs Po Plotssupporting

confidence: 68%

Section: Calibration Of E Vs Po Plotsmentioning

confidence: 99%

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Potentiometric study of acid–base equilibria in the {KCl+LiCl} eutectic melt at temperatures in the range (873 to 1073) K

Cherginets¹,

Demirskaya²,

Rebrova³

2004

The Journal of Chemical Thermodynamics

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“…In order to understand chemical and electrochemical behavior of oxide ion, it is indispensible to measure the thermodynamic quantities of oxide ion such as chemical potentials in molten chlorides. Some researchers previously reported on the oxygen electrode reaction in molten chlorides [3][4][5][6][7], however, these results did not coincide with each other, which was attributed to the fact that an oxygen evolution selective electrode on which the oxygen evolution only occurs without side reactions such as dissolutions of the electrode at high temperatures was not available. That is why thermodynamic consideration on the electrochemical processes involving oxide ion such as reduction processes of MOx (M = U, Si, Ti, etc.)…”

Section: Introductionmentioning

confidence: 95%

Thermodynamics of the O2/O2− redox couple in molten (LiCl+KCl+Li2O) systems

Kado

Goto

Hagiwara

2010

The Journal of Chemical Thermodynamics

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a b s t r a c t Activity coefficients of oxide ion were determined by the measurements of the standard formal potential of O 2 /O 2À with a boron-doped diamond (BDD) electrode in molten (LiCl + KCl): LiCl:KCl = {58.5:41.5 (eutectic), 65:35, 70:30, 75:25} mol% at T = (673 to 803) K.The activity coefficient decreases with the increase of the LiCl content in the melt: (18.7 ± 1.5, 7.7 ± 1.0, 4.1 ± 0.4, and 1.6 ± 0.1), respectively, at T = 773 K in each melt. The result is explained by the attractive force between Li + and O 2À which is stronger than that between K + and O 2À .

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“…[106][107][108] Additionally, experimental observation of hyperlithiated oxygen, in the form of Li 3 O and Li 4 O has been reported, a fact that is potentially important to the LiCl-Li 2 O-Li electrolyte in question. [108][109][110][111] 112 The electrical conductivity of the LiCl-Li system is exceedingly small compared to other metal-salt solutions, specifically the other alkali-alkali halides. 80,[92][93][94]113 This behavior has been attributed to the formation of a high population of bound F-centers in the LiClLi system, as opposed to the loosely bound electrons that are more probable in alternative systems; for example Na-NaI.…”

Section: -29mentioning

confidence: 99%

Review—Metallic Lithium and the Reduction of Actinide Oxides

Merwin

Williamson

Willit

et al. 2017

J. Electrochem. Soc.

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Extensive research and process development has been conducted on the electrolytic reduction of actinide oxides in molten LiCl-Li 2 O. It is now accepted that the reduction of these metal oxides occurs via two separate reduction mechanisms: direct electro-chemical reduction and mediated chemical reduction by metallic lithium. The deposition of metallic lithium at the cathode (mediated chemical reduction mechanism) during the process is known to be essential in order to achieve high process throughputs and reduction yields, and yet a knowledge gap exists regarding the nature of metallic lithium in this system. This review summarizes the formation of lithium during the process and its dispersion into the molten salt electrolyte. Previously reported aspects of the physical chemistry of the LiCl-Li 2 O-Li system are presented with a specific focus on the dispersion of Li in the solution. Finally, issues regarding the effect of the presence of lithium on the electrolytic reduction process are discussed. Evidence shows that electrochemically generated metallic lithium is likely a significant source of experimental uncertainty, low current efficiency and Li 2 O consumption in the oxide reduction process. The reduction of uranium, plutonium and minor actinide oxides to a metallic form is an important nuclear fuel cycle process.2-9 The ability of metallic lithium to reduce various uranium oxides, importantly UO 2 and U 3 O 8 , has been known for many years.10 A molten salt metalothermic reduction process employing metallic lithium (Li) as a reductant dissolved in molten LiCl was first developed by Argonne National Laboratory (ANL) to consolidate a variety of forms of actinide oxides for integration into a single electrometallurgical reprocessing system. 11-13 An electrolytic process, often referred to as electro-deoxidation or simply oxide reduction, was subsequently developed as a more controllable method of reducing metal oxides. A feasibility study conducted by Poa et al. demonstrated that oxides of uranium and plutonium could be reduced electrochemically in molten salts as long as the reduction potential of the metal oxide in question was more noble than the cation of the electrolyte.14,15 This approach was further developed by Gourishankar et al. to better understand processes chemistry and develop the electrolytic cell technology. 13,[16][17][18][19][20] Independent research conducted by Fray, Farthing, and Chen (FFC) applied the principles of electrochemical reduction in molten salt electrolytes to a variety of metal oxide reduction processes. 21,22 The FFC process has been the subject of several literature reviews.23-25 While these review articles address the processes associated with the reduction of nuclear fuel in LiCl, they focus on the electro-deoxidation phenomena and the CaCl 2 -CaO system. Additionally, the process engineering of the electrolytic reduction of nuclear fuel, and experience in incorporating oxide fuel into pyroprocessing, has been the focus of a recent review article. 26 The current review wi...

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Oxide ion electrodes and oxide ion donors in molten alkaline halogenides. A consideration of potentiometric studies

Cited by 28 publications

References 35 publications

Potentiometric study of acid–base equilibria in the {KCl+LiCl} eutectic melt at temperatures in the range (873 to 1073) K

Potentiometric study of acid–base equilibria in the {KCl+LiCl} eutectic melt at temperatures in the range (873 to 1073) K

Thermodynamics of the O2/O2− redox couple in molten (LiCl+KCl+Li2O) systems

Review—Metallic Lithium and the Reduction of Actinide Oxides

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