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The kinetic and thermodynamic properties of La(III) in LiCl–KCl–LaCl3 melts on inert electrode (Mo) were investigated by different electrochemical methods. The reduction of La(III) into metallic La on the Mo electrode is a quasi-reversible process that can transfer three electrons in a single step. In the temperature range of 723–848 K, the diffusion coefficient and reaction activation energy of La(III) in LiCl–KCl–LaCl3 melts were calculated using Cyclic voltammetry (CV) and Chronopotentiometry (CP). Moreover, relationships between the diffusion coefficient with temperature were formulated as follows: lnD0 = − 3.32/T + 5.27 (CV) and lnD0 = − 4.7/T − 5.89 (CP). The dependence of exchange current density of La(III)/La(0) on the experimental temperatures was constructed by Tafel (lnj0 = − 2.04/T − 1.93) and Linear polarization (LP) (lnj0 = − 2.74/T − 0.912). The apparent electrode potentials, Gibbs free energy, and activity coefficient of La(III)/La(0) were estimated using Open-circuit chronopotentiometry (OCP). Different LaCl3 concentrations were added to LiCl–KCl melts, and the ion concentration of La(III) in the melts was determined using Normal Pulse Voltammetry (NPV). The obtained results had a relative error of less than 10% when compared to the ICP results. It shows that the results obtained by NPV detection are accurate and reliable. [ABSTRACT FROM AUTHOR]

The chlorination of UO2 in presence of Nd2O3, Pr6O11, CeO2 and La2O3 in LiCl–KCl melt using AlCl3 and Al metal at 773 K is studied here. All the oxides were chlorinated and the extent of conversion of UO2, Nd2O3 and Pr6O11 was quantified through UV–Vis spectroscopy whereas for quantification of CeO2 and La2O3, inductively coupled plasma optical emission spectroscopy (ICP-OES) was employed. Conversion of ~ 92% for UO2 and ~ 95% for lanthanide (Nd, Pr) oxide was achieved when each of them was chlorinated independently. The results showed that the presence of even a single lanthanide oxide reduces the conversion efficiency of UO2. The conversion efficiency of UO2 in presence of all the lanthanide oxides studied here decreased by nearly 12%. The effect of lanthanide oxides on the chlorination of UO2 using AlCl3 and Al metal and their quantification by UV–Vis spectrophotometry is reported in the present study. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of Yb(III) was studied at a W electrode in LiCl–KCl–ZnCl2 molten salt system. Cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and chronopotentiometry were used to investigate the electrochemical co-deposition of Yb(III) and Zn(II) in LiCl–KCl melt. Extraction efficiency of Yb(III) from LiCl–KCl–ZnCl2 melt was calculated to be 99.49% after potentiostatic electrolysis for 40 h. Zn–Yb alloys were prepared by galvanostatic electrolysis through co-deposition of Zn(II) and Yb(III) for 3 h. XRD and SEM–EDS were used to analyze the components and morphology. YbZn2 intermetallic compound is the most stable product under the experimental electrolysis conditions. [ABSTRACT FROM AUTHOR]

In this paper, the electrochemical behaviors of Pb(II) and Pr(III) were investigated on W electrode in LiCl–KCl melts, respectively. The results illustrated that the reduction of Pb(II) and Pr(III) was a one step process. When the PbCl2 and PrCl3 co-existed in the molten salt, the cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry illustrated that four kinds of Pb-Pr intermetallic compounds were formed at 773 K. Whereafter, the electrochemical behavior of Pr(III) on liquid Pb cathode was studied by cyclic voltammetry in LiCl–KCl melts, and the result showed that only one kind of Pb-Pr intermetallic compound was formed at 773 K. The Pr element was extracted by galvanostatic and potentiostatic electrolysis with the assistance of Pb cathode in LiCl–KCl–PrCl3 melts, respectively. Finally, the obtained alloys were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and the result illustrated that the prepared intermetallic compound mainly is Pb3Pr. [ABSTRACT FROM AUTHOR]

In this work, laser induced breakdown spectroscopic (LIBS) technique is utilized to estimate U in presence of large excess of lithium and potassium chloride (LiCl–KCl) or Cd mixtures. Colloidal solution of hydroxides of U, produced by adding NaOH was spread over filter paper and subjected to LIBS analysis after drying in air. Nearly 50 times enhancement in the LIBS signal was found as compared to normal solution. Using Er as an internal standard, emission line of U(II) at 385.957 nm shows linearity from 50 to 600 ppm. The detection limit of U was found to be 21 ppm. The presence of 5% LiCl–KCl salt or 3% Cd does not alter the calibration plot significantly. The estimations of U in synthetic samples agree well with the values measured by spectrophotometric method. [ABSTRACT FROM AUTHOR]

The distillation behaviors of some fission product fluorides in LiCl–KCl system were investigated. For rare earth element, the corresponding decontamination factors (DFs) of Ce in 5 wt% CeF3–LiCl–KCl salts were over 100 at 1040 K and 13 Pa. For SrF2, the very poor DFs was deduced for the presence of more volatile SrClF, while Zr4+ was observed to complex easily with F− and Cl−, which affected its evaporation rate and the separation efficiency. F ion concentration in condensate salt was 1–2 level higher than the metal ion due to the stronger covalent band. [ABSTRACT FROM AUTHOR]

Electrochemical and kinetic properties of samarium (Sm) in LiCl–KCl eutectic salt were investigated at various concentrations and temperatures. Cyclic voltammetry (CV) were performed to determine diffusion coefficient and the rate constant (k0). In addition, electrochemical impedance spectroscopy (EIS) was conducted for further understandings on the kinetic behaviors of Sm(III)/Sm(II) couple. The values of the diffusion coefficients were in the range of 3.54 × 10−6 to 9.58 × 10−5 cm2 s−1 and the values of k0 were estimated to be in the range of 0.63 × 10−2 to 1.11 × 10−2 cm s−1. The values of i0 for Sm(III)/Sm(II) were computed by obtaining the charge transfer resistance from the curve fitting analysis, ranging from 1.04 × 10−3 to 2.97 × 10−3 A cm−2. [ABSTRACT FROM AUTHOR]

A fast, precise and simple spectrophotometric method was developed for the estimation of uranium in LiCl–KCl salt matrix using phosphoric acid as a complexing agent. The 421 nm absorbance peak of uranium was found to be spectral interference free and area of this peak was used for the quantitative analysis. Linearity over 100–7000 ppm with a detection limit of 25 ppm of uranium in 10% LiCl–KCl matrix was obtained by this method. The present method was successfully applied for the quantitative estimation of uranium in synthetic salt mixtures and the results were found to be more accurate than the values measured by ICP-OES. [ABSTRACT FROM AUTHOR]

This work presents a comprehensive study for the electrochemical behaviors of zirconium in LiCl-KCl eutectic. The effects of stirring, temperature and Zr concentration on the electrode reactions, the ZrCl4 sublimation from the melt, microcosmic morphologies of Zr deposits (ZrCl and Zr) obtained at different potential and temperature have been investigated. The behaviors of Zr(IV), on a large concentration range from 0.13% to 2.28% in melt, show a multiple-step reaction involving Zr(IV), Zr(II), ZrCl and Zr species. Temperature plays a crucial role on the changes of Zr(IV) reduction behavior on the solid electrode. The Zr(IV)/ZrCl couple is more easily observed at lower temperature and gradually diminishes with the increase of temperature. The Zr(IV)/Zr(II) and Zr(II)/Zr reactions are predominant on the W electrode at higher temperatures. At 673 K, a layered structure of insoluble ZrCl formed by potentiostatic electrolyses at 1.1 V was visualized by scanning electron microscopy-energy dispersive X-ray (SEM-EDS), while only Zr metal particles was observed at higher temperature than 773 K. An evolution of the Zr-based structure and size corresponding to the ZrCl and Zr metal based on different potentiostatic electrolysis was observed. The average particle size of the Zr metalparticles increases with the increase of temperature. [ABSTRACT FROM AUTHOR]

Anhydrous ytterbium chloride was obtained via solid-phase reaction from YbO with AlCl as a chlorination agent. The electrochemical behavior of the chloridized YbO was investigated on W electrodes in LiCl-KCl and LiCl-KCl-AlCl melts by cyclic voltammetry and square wave voltammetry. The results showed that the reduction/reoxidation of Yb(III)/Yb(II) was reversible and controlled by diffusion. The signals related to the formation of two Al-Yb intermetallic compounds were detected in LiCl-KCl-AlCl melt. Potentiostatic electrolysis was carried out in LiCl-KCl-AlCl-YbCl melt on W electrodes at 943 K at different potentials and AlYb, AlYb, AlLi and AlLi phases were detected in deposits. Then, the extraction of ytterbium was performed. The currents evolution was recorded by square wave voltammetry and the extraction efficiency was evaluated via inductive coupled plasma atomic emission spectrometer analysis during electrolysis. The initial extraction rate is much higher than that at longer times. The extraction efficiency was about 98.0 % for Yb(III) after potentiostatic electrolysis for 60 h at −1.84 V in LiCl-KCl-AlCl-YbCl melt. [ABSTRACT FROM AUTHOR]

Electrochemical deposition of Mg, Li and Ag on molybdenum electrodes in LiCl-KCl-MgCl-AgCl melts at 943 K to form Mg-Li-Ag alloys was investigated. Cyclic voltammograms (CVs) showed that the potential of Li metal deposition, after the addition of MgCl and AgCl, was more positive than that of Li metal deposition before the addition. α, AgMg + α, and α + β + LiAg phases of Mg-Li-Ag alloys were obtained by galvanostatic electrolysis. The element Mg distributed homogeneously in the alloys while element Ag mainly located on the grain boundaries. [ABSTRACT FROM AUTHOR]

In order to enhance the efficiency of pyrochemical technology, especially electrorefining process, physicochemical data of trivalent uranium in LiCl-KCl eutectic at 773 K were measured, including molar absorptivity, formal potential and diffusion coefficient of U ions. The molar absorptivities of U were determined to be 765 ± 48 and 686 ± 39 M cm at 465 and 550 nm, respectively. The formal potential of U/U redox couple and diffusion coefficient of U ions were measured to be −0.308 V vs. Ag/Ag and 8.7 × 10 M cm, respectively. To elucidate the chemical behavior of U ions under the existence of oxide ions, U ions were reacted with oxides ions in situ produced at the LiCl-KCl media. Surprisingly, it was revealed from XRD patterns that UO was formed from the reaction between U ions and O ions with the molar ratio of 1:1. [ABSTRACT FROM AUTHOR]