Electrochemical and thermodynamic properties of U4+ and U3+ on Mo electrode in LiCl-KCl eutectic

2019 ◽  
Vol 107 (2) ◽  
pp. 95-104
Author(s):  
Ru-Shan Lin ◽  
You-Qun Wang ◽  
Zhao-Kai Meng ◽  
Hui Chen ◽  
Yan-Hong Jia ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Electrochemical Behavior ◽  
Diffusion Coefficients ◽  
Electrochemical Techniques ◽  
Reduction Process ◽  
Standard Potential ◽  
Hcl Gas ◽  
Thermodynamic Functions Of Formation

Abstract In this study, UCl4 was prepared by the reaction of HCl gas with UO2 in the LiCl-KCl eutectic. Then, the electrochemical behavior of U4+ and U3+ on a Mo cathode was investigated by various electrochemical techniques. The reduction process of U4+ was regarded as two steps: U4++e=U3+; U3++3e=U. Diffusion coefficients of U4+ and U3+, the apparent standard potential of U4+/U3+, U3+/U as well as U4+/U in the LiCl-KCl molten salt on the Mo electrode was determined by numerous electrochemical methods. The thermodynamic functions of formation of Gibbs free energy of UCl4 and UCl3 are calculated as well.

scholarly journals Reprocessing of LiH in Molten Chlorides

2008 ◽  
Vol 63 (5-6) ◽  
pp. 377-384
Author(s):  
Patrick J. Masset ◽  
Armand Gabriel ◽  
Jean-Claude Poignet
Keyword(s):  
Process Design ◽  
Diffusion Coefficients ◽  
Electrochemical Techniques ◽  
Hydrogen Gas ◽  
Standard Potential ◽  
Molten Chlorides ◽  
Metallic Lithium ◽  
Production Of Hydrogen ◽  
Current Densities ◽  
Molten Phase

LiH was used as inactive material to stimulate the reprocessing of lithium tritiate in molten chlorides. The electrochemical properties (diffusion coefficients, apparent standard potentials) were measured by means of transient electrochemical techniques (cyclic voltammetry and chronopotentiometry). At 425 ºC the diffusion coefficient and the apparent standard potential were 2.5 · 10−5 cm2 s−1 and −1.8 V vs. Ag/AgCl, respectively. For the process design the LiH solubility was measured by means of DTA to optimize the LiH concentration in the molten phase. In addition electrolysis tests were carried out at 460 ºC with current densities up to 1 A cm−2 over 24 h. These results show that LiH may be reprocessed in molten chlorides consisting in the production of hydrogen gas at the anode and molten metallic lithium at the cathode.

scholarly journals Heat Capacities and Thermodynamic Properties of Pinnoite and Inderite

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Hanyu Zheng ◽  
Kangrui Sun ◽  
Long Li ◽  
Yafei Guo ◽  
Tianlong Deng
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Thermodynamic Functions ◽  
High Purity ◽  
Heat Capacities ◽  
Thermal Anomalies ◽  
Natural Minerals ◽  
First Time

In this paper, in order to understand the thermodynamic properties of natural minerals of pinnoite (MgB2O4·3H2O, Pin) and inderite (Mg2B6O11·15H2O, Ind) deposited in salt lakes, heat capacities of two minerals were measured using a precision calorimeter at temperatures from 306.15 to 355.15 K after the high purity was synthesized. It was found that there are no phase transitions and thermal anomalies for the two minerals, and the molar heat capacities against temperature for Pin and Ind were fitted as Cp,m,pin = −2029.47058 + 16.94666T − 0.04396T2 + 3.89409×10−5T3 and Cp,m,Ind = −30814.43795 + 282.68108T − 0.85605T2 + 8.70708×10−4T 3, respectively. On the basis of molar heat capacities (Cp,m) of Pin and Ind, the thermodynamic functions of entropy, enthalpy, and Gibbs free energy at the temperature of 1 K interval for the two minerals were obtained for the first time.

scholarly journals Thermodynamıc Propertıes of the BiTe and Bi8Te9 Compounds

2020 ◽  
Vol 21 (4) ◽  
pp. 714-719
Author(s):  
G.S. Hasanova ◽  
A.I. Aghazade ◽  
Y.A. Yusibov ◽  
M.B. Babanly
Keyword(s):  
Comparative Analysis ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Partial Functions ◽  
Two Phase ◽  
Standard Thermodynamic Functions ◽  
Temperature Range ◽  
First Time ◽  
Thermodynamic Functions Of Formation

Two-phase alloys Bi8Te9+Bi4Te5 and BiTe+Bi8Te9 were studied by the electromotive forces method (EMF) in the temperature range 300-450 K. From the EMF data, the relative partial molar functions of bismuth in the alloys were calculated. The potential-forming reactions responsible for these partial functions were compiled, the values of the standard thermodynamic functions of formation, and the standard entropies of Bi8Te9 and BiTe compounds were calculated. A comparative analysis of the data for BiTe with the literature data was carried out; for Bi8Te9, the thermodynamic functions were obtained for the first time.

scholarly journals Heat Capacity and Thermodynamic Properties of Cesium Pentaborate Tetrahydrate

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Kangrui Sun ◽  
Panpan Li ◽  
Long Li ◽  
Yafei Guo ◽  
Tianlong Deng
Keyword(s):  
Phase Transition ◽  
Heat Capacity ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Molar Heat Capacity ◽  
Polynomial Equation ◽  
Adiabatic Calorimeter ◽  
Nitrogen Atmosphere ◽  
Thermal Anomalies

This paper reports the molar heat capacities of β-CsB5O8·4H2O, which were measured by an accurate adiabatic calorimeter from 298 to 373 K with a heating rate of 0.1 K/min under nitrogen atmosphere. Neither phase transition nor thermal anomalies were observed. The molar heat capacity against temperature was fitted to a polynomial equation of Cp,m (J·mol−1·K−1) = 618.07702 + 39.52669[T − (Tmax + Tmin)/2]/(Tmax − Tmin)/2] − 3.46888[(T − (Tmax + Tmin)/2)/(Tmax − Tmin)/2]2 + 7.9441[(T − (Tmax+ Tmin)/2)/(Tmax − Tmin)/2]3. The relevant thermodynamic functions of enthalpy (HT − H298.15), entropy (ST − S298.15), and Gibbs free energy (GT − G298.15) of cesium pentaborate tetrahydrate from 298 to 375 K of 5 K intervals are also obtained on the basis of relational expression equations between thermodynamic functions and the molar heat capacity.

scholarly journals THERMODYNAMIC FUNCTIONS OF FORMATION OF LITHIUM TITANATES

2021 ◽  
Vol 0 (4) ◽  
pp. 60-66
Author(s):  
U.N. Sharifova ◽  
Keyword(s):  
Free Energy ◽  
Enthalpy Of Formation ◽  
Thermodynamic Functions ◽  
Standard Entropy ◽  
Standard State ◽  
Temperature Range ◽  
Lithium Glass ◽  
Binary Compounds ◽  
First Time ◽  
Thermodynamic Functions Of Formation

By the method of electromotive forces measuring concentration chains: Pt│Li2O│ ZrO2+10 wt% Y2O3, lithium glass. (Li2O)x(TiO2)1-x│Pt in the temperature range T=1000–1200K and concentrations 0.35÷0.95 mol fraction TiO2, the thermodynamic functions of the formation of the compounds Li4TiO4, Li2TiO3, Li4Ti5O12 and phases based on Li2TiO3:Li1.92Ti1.04O3.04, Li2.12Ti0.94O2.92 were determined. With the exception of the compound Li2TiO3, the thermodynamic functions of the formation of lithium titanates are deter¬mined for the first time. The thermodynamic functions of formation are calculated for the 1200 K and for the standard state at 298 K. The thermodynamic functions of the formation of lithium titanates are determined from simple substances and from binary compounds Li2O and TiO2. In particular, for the free energy, enthalpy of formation and standard entropy we obtained: ∆G_298^0(Li4TiO4)=–2149 kJ∙mol-1; ∆G_298^0(Li2TiO3)=–1565; ∆G_298^0(Li4Ti5O12)=–5923; ∆H_298^0(Li4TiO4)=–2286 kJ∙mol-1; ∆H_298^0(Li2TiO3)=–1662; ∆H_298^0(Li4Ti5O12)=–6287; S_298^0(Li4TiO4)=119.1 J∙mol-1∙K-1; S_298^0(Li2TiO3)=84; S_298^0(Li4Ti5O12)=315.7

scholarly journals Thermodynamic properties of the GdTe3 compound

2021 ◽  
Vol 22 (3) ◽  
pp. 420-425
Author(s):  
Samira Imamaliyeva
Keyword(s):  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Standard Entropy ◽  
X Ray Diffraction ◽  
Emf Measurements ◽  
Standard Thermodynamic Functions ◽  
X Ray ◽  
Temperature Range ◽  
Concentration Cells ◽  
Thermodynamic Functions Of Formation

The alloys of the Gd-Te system in the range of compositions > 75 at% Te were studied by the methods of X-ray diffraction (XRD) and electromotive forces (EMF). From the EMF measurements of the concentration cells relative to the GdTe electrode in the 300-450 K temperature range, the partial thermodynamic functions of GdTe in alloys were determined. By combining these data with the corresponding functions of Gd in GdTe, the partial molar functions of gadolinium in GdTe3+Te alloys, and standard thermodynamic functions of formation and standard entropy of the GdTe3 compound were calculated. The obtained results were compared with the literature data.

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

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