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The key fragment element samarium (Sm) has a large neutron absorption cross section, which can hinder the absorption of neutrons by uranium and negatively affect the nuclear reaction. In order to realize the nuclear fuel cycle, the extraction of Sm was studied on the basis of electrolytic refining after the dry process. The electrochemical properties of SmCl3 and SnCl2 in LiCl-KCl molten system were systematically investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential (OCP). The diffusion coefficients of the Sn(II) and Sm(III) electrode processes were calculated to be 3.55–5.93 × 10−5 and 2.33–3.97 × 10−5 cm2 s−1, respectively. The co-reduction of Sm(III) and Sn(II) ions was studied. Sm was recycled by constant current electrolysis on the liquid Sn electrode, and the average extraction rate was about 94.23%. The samples were characterized and analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM), and the results showed that Sm extraction from liquid tin is feasible. [ABSTRACT FROM AUTHOR]

To improve the separation capacity of uranium in aqueous solutions, 3R-MoS2 nanosheets were prepared with molten salt electrolysis and further modified with polypyrrole (PPy) to synthesize a hybrid nanoadsorbent (PPy/3R-MoS2). The preparation conditions of PPy/3R-MoS2 were investigated and the obtained nanosheets were characterized with scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS). The results showed that PPy/3R-MoS2 exhibited enhanced adsorption capacity toward U(VI) compared to pure 3R-MoS2 and PPy; the maximum adsorption was 200.4 mg/g. The adsorption mechanism was elucidated with XPS and FTIR: (1) negatively charged PPy/3R-MoS2 nanosheets attracted UO22+ by an electrostatic interaction; (2) exposed C, N, Mo, and S atoms complexed with U(VI) through coordination; (3) Mo in the complex partly reduced the adsorbed U(VI) to U(IV), which further regenerated the adsorption point and continuously adsorbed U(VI). The design of the PPy/3R-MoS2 composite with a high adsorption capacity and chemical stability provides a new direction for the removal of radionuclide. [ABSTRACT FROM AUTHOR]

• Potentiostatic electrolysis were performed to extract Y on Ga electrode, and the highest extraction raido of Y(III) reach to about above 99%. • The optimal initial addition amount of gallium was calculated through multiple experiments to improve the circulation utilization rate of gallium electrode. • The thermodynamic and kinetic parameters of Y and Ga were investigated by means of transient electrochemical techniques. • Our researching results provide theoretical basis for extraction and separation of Lns and Ans. To recover the rare earth element yttrium (Y) from spent fuel by molten salt electrolysis technology, the electrochemical redox mechanism of Y(III) and Ga(III) ions on tungsten electrode and the electrode reaction of Y(III) ions on the liquid Ga electrode were systematically detected by a series of electrochemical test methods, including cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry, etc. The thermodynamic and kinetic parameters of the electrode process on Ga(III) and Y(III) ions were obtained in this work. The measured diffusion activation energies (E a) of electrode process for Y(III) and Ga(III) ions were calculated as 30.40 kJ·mol−1 and 33.33 kJ·mol−1. The electrodeposition process of Y and Ga was studied by CV and OCP, and thermodynamic parameters of Ga-Y alloys formed were also calculated. Thermodynamic parameters of Ga 2 Y intermetallic compounds were calculated based on open circuit chronopotentiometry at different temperatures (Δ H f 0 (Ga 2 Y) = - 279.205 kJ m o l - 1 and Δ S f 0 (G a 2 Y) = - 123.9 J m o l - 1 K - 1 ). Yttrium was extracted by potentiostatic electrolysis and galvanostatic electrolysis on liquid Ga electrode in molten salts. In order to save the amount of liquid metal gallium, the best initial (2.5 g) was used. The cathodic deposition Products were characterized by X-ray diffraction analysis and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. According to ICP-AES analysis, the extraction rate of Y on Ga electrode can reach a maximum of 99.39%. [ABSTRACT FROM AUTHOR]

For the development of nuclear energy, it is important to remove the fission products which hinder nuclear reactions. In this paper, Gd was extracted by an electrochemical method in LiCl-KCl molten salts. The electrochemical reactions of GdCl 3 and SnCl 2 are measured by a series of electrochemical means. Three kinds of Sn-Li and four Sn-Gd alloys are obtained by cyclic voltammetry and other electrochemical means. Thermodynamic and kinetic parameters of electrode processes for Gd(III) and Sn(II) ions are calculated by different electrochemical test methods. The diffusion coefficient and diffusion activation energy of the Sn(II) ion are reactions as 2.23–3.78 × 10-5 cm2 s-1 and 24.4 kJ mol-1, respectively. Thermodynamic parameters of Sn 3 Gd intermetallic compounds were calculated based on open circuit chronopotentiometry at different temperatures (Δ H f 0 (Sn 3 G d) = − 229.225 kJ m o l - 1 and Δ S f 0 (Sn 3 G d) = − 38.2 J m o l - 1 K - 1 ). Metallic Gd is extracted by potentiostatic and galvanostatic electrolysis on liquid Sn electrode in melts, respectively. According to X-ray diffraction (XRD) and scanning electron microscopy and elemental dispersive spectrometry (SEM-EDS), the products are mainly composed of the intermetallic compound Sn 3 Gd and Sn metal. The experimental results show that the fission element Gd can be extracted with high extraction rate by electrolysis in molten salt system. [Display omitted] • Potentiostatic electrolysis were performed to extract Gd on Sn electrode, and the highest extraction raido of Gd(III) reach to about above 99%. • The thermodynamic and kinetic parameters of Gd and Sn were investigated by means of transient electrochemical techniques. • Our researching results provide theoretical basis for extraction and separation of Lns and Ans. [ABSTRACT FROM AUTHOR]

In order to investigate the application prospects for the extraction of fission products neodymium (Nd) by electrolytic refining at active plumbum (Pb) electrodes, the reduction mechanism of Nd(III)/Pb(II) at inert tungsten, and Nd(III) at Pb thin film electrodes was investigated. This work simultaneously presents the results of kinetic and thermodynamic parameter of Pb(II)/Nd(III). The composition of the Pb–Nd alloy compound formed on the activated Pb electrode was determined by X-ray diffraction analysis (XRD) and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and the thermodynamic parameters of the formed Pb 3 Nd alloy were calculated: Δ H f 0 P b 3 Nd = − 219.92 kJ mol − 1 and Δ S f 0 Pb 3 Nd = − 47.48 J mol − 1 K − 1. Nd(III) was extracted in the form of Pb–Nd alloy by constant potential electrolysis (PE) in LiCl–KCl melt. Based on the analysis of inductively coupled plasma-atomic emission spectrometry (ICP-AES) results, the average extraction rate of Nd(III) ions at the liquid Pb electrode could reach 99.03%. [ABSTRACT FROM AUTHOR]

• The results are vital to electroextraction and thermochemistry of Gd on Pb electrode. • Electrochemical parameters are meaningful to dry reprocessing of nuclear fuel. • Extraction raido of Gd on Pb electrode is about 99% by potentiostatic electrolysis. • The parameters were investigated by means of transient electrochemical techniques. • The results provide theoretical basis for extraction and separation of Lns and Ans. In order to electrolytically recover slivers of fission elements Gd from spent fuel, the electrochemical behavior of GdCl 3 and PbCl 2 on inert tungsten electrode in LiCl-KCl melts was systematically investigated by cyclic voltammetry (CV), square wave voltammetry (SWV) and open circuit chronopotentiometry (OCP). The kinetic and thermodynamic parameters of electrode process on Pb(II) and Gd(III) ions were also calculated by electrochemical methods. The results revealed that the diffusion activation energies (E a) of Gd(III) and Pb(II) are 31.81 kJ·mol−1 and 31.9 kJ·mol−1; the Δ G f ∗ 0 and Δ H f ∗ 0 of Gd(III) are −1035.87 kJ·mol−1 and −198.6 J·mol−1·K−1, Pb(II) are −294.75 kJ·mol−1 and −60.5 J·mol−1·K−1, respectively. The co-reduction behaviors of Gd(III) and Pb(II) ions were also studied, and three Gd x Pb y intermetallic compounds were detected by CV and OCP techniques. In order to study the deposition mechanism of Pb 3 Gd intermetallic compounds, its thermodynamic parameters were calculated. In addition, potentiostatic/galvanostatic electrolysis were carried out to extract Gd on plumbum membrane electrode. The results showed that the recovered Gd was in the form of Pb 3 Gd intermetallic compound at −1.75 V. The cathodic deposits of ion were characterized by X-ray and scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that Gd was extracted on plumbum membrane electrode with high extraction rate by ICP-AES analysis. [ABSTRACT FROM AUTHOR]

The efficient removal of uranium from aqueous solution remains of great challenge in securing water environment safety. In this paper, we reported a high temperature electrochemical method for the preparation of EuVO 4 with different morphologies from rare earth oxides and vanadate, which solved the problems of rare earth and vanadium recovery. The effects of pH, ionic strength, contact time, initial concentration and reaction temperature on the adsorption of U(VI) by prepared adsorbent were studied by static batch experiments. When the concentration of U(VI) standard is 100 mg g−1, the maximum adsorption capacity of EuVO 4 is 276.16 mg g−1. The adsorption mechanism was elucidated with zeta potential and XPS: 1) negatively charged EuVO 4 attracted UO 2 2+ by electrostatic attraction; 2) exposed Eu, V, and O atoms complexed with U(VI) through coordination; 3) the hybrid of Eu was complex, which accommodated different electrons to interact. In the multi-ion system with Al3+, Zn2+, Cu2+, Ni2+, Cr2+ and Mn2+, EuVO 4 also showed good selective adsorption properties for U(VI). Five adsorption and desorption cycle experiments demonstrated that EuVO 4 possessed good renewable performance. • Different morphologies of EuVO 4 were synthesized by high-temperature electrochemical method. • U(VI) sorption on EuVO 4 was studied using batch and spectroscopies. • The maximum adsorption capacity of EuVO 4 reached at 276.16 mg g−1. • EuVO 4 showed good selective adsorption property for U(Ⅵ) in the multi-ion system. [ABSTRACT FROM AUTHOR]