Electrochemical Deposition of NiFe Alloy at a Temperature of 70°C

Russian Journal of Electrochemistry - The heating of chloride electrolyte to a temperature of 70°C excludes anomalous codeposition of NiFe alloy components as a result of a change of the...     

Electrochemical formation of a cesium–tin alloy in an amide-type ionic liquid

Electrochemical formation of cesium–tin alloys in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing 0.5 M CsTFSA has been studied. Cathodic decomposition of BMPTFSA on a platinum electrode was suppressed by addition of CsTFSA, suggesting that Cs⁺ accumulated on the electrode surface and hindered the reduction of BMPTFSA. Multiple cathodic current peaks were observed on a tin electrode in the ionic liquid. Energy-dispersive X-ray analysis and X-ray diffraction results suggested formation of cesium–tin alloys after potentiostatic cathodic reduction on the tin electrode at room temperature.     

Electrochemical separation of uranium and cerium in molten LiCl–KCl

The electrochemical separation of uranium from cerium in LiCl–KCl eutectic and the electrochemical behavior of Ce(III) were studied. According to the cyclic voltammogram of Ce(III) and the former result of U(III), electrodeposition potential was determined at ?1.65 V (vs Ag/AgCl). The uranium metal was successfully deposited and separated from cerium. The morphology of deposit and cross section of electrode were investigated by SEM, firstly uranium deposit alloys with stainless steel and forms a thin transition layer, and secondly the uranium metal layer grows from the transition layer. The separation factors of uranium/cerium on different recovery ratios were determined through a series of steps. It was found that the content of cerium in the deposit and separation factors declined with increasing the initial concentration of U³⁺ in molten salts; the separation factors remained stable at around 20 in different uranium recovery ratios.     

Solution behavior of metoclopramide in aqueous-alcoholic solutions at 30°C

Densities (ρ) and refractive indices (n_D) of solutions of antiemetic drug metoclopramide (4-amino-5-chloro-N-(2-(diethylamino)ethyl)-2-methoxybenzamide hydrochloride hydrate) in methanolwater and ethanol-water mixtures of different compositions were measured at 30°C. Apparent molar volume (φ_v) of the drug was calculated from density data and partial molar volumes (φ_v⁰) were determined from Massons relation. Concentration dependence of nD has been studied to determine refractive indices of solution at infinite dilution (n_D⁰). Results have been interpreted in terms of solute-solvent interactions.     

Solubility of europium oxides in NaI melts at 700°C

The solubility product of EuO (pP _EuO = 8.65 ± 0.5) and its dissociation constant (pK _EuO = 5.67 ± 0.5) in NaI melts at 700°C have been determined by potentiometric titration with the use of a Pt(O₂)|ZrO₂(Y₂O₃) membrane oxygen electrode. Estimated on the basis of these parameters, the total solubility of EuO in NaI melts (1.12 × 10⁻³ mol/kg, logs _EuO = −2.95) is close to the value obtained by the consecutive additions method (2.8 × 10⁻³ mol/kg, logs _EuO = −2.55). The values obtained show that Eu²⁺ (EuI₂) is a stable cationic activator in NaI melt, but it yet cannot be recommended as an agent for the removal of oxygen-containing admixtures from this melt.     

The Solubility of Hydrogen Sulfide in Acetonitrile at 25°C

Abstract

The solubility of hydrogen sulfide in acetonitrile at 25°C has been determined both gravimetrically and titrimetrically to be 0. 528 M. The effects of the presence of water and an electrolyte (LiClO₄) on this parameter are reported.     

Volumetric properties of cyclic hydrocarbons in tetrachloromethane at 25°C

By means of a vibrating-tube densimeter, the densities at 25°C have been determined for binary mixtures of tetrachloromethane with a liquid (cyclodecane, cis-decahydronaphthalene, trans-decahydronaphthalene, bicyclohexyl, pentane) or a solid hydrocarbon (cyclododecane, cyclopentadecane, norbornane, adamantane, octahydro-4,7-methano-1H-indene). Excess molar volumes have been obtained in the whole mole fraction range for mixtures containing a liquid hydrocarbon. For solid cycloalkanes, apparent molar volumes have been evaluated in the whole range of miscibility. The partial molar volumes at infinite dilution have been calculated for all examined cycloalkanes and compared with those of n-alkanes. The dependence of upon the size and shape of the ring or cage structure of the solute is discussed. The capability of the Flory theory to reproduce V^E for these mixtures is also tested.     

Electrochemical and spectroscopic investigations of Tb(III) in molten LiCl–KCl eutectic at high temperature

Electrochemical and spectroscopic properties of Tb(III) in molten LiCl–KCl eutectic at high temperature were investigated by cyclic voltammetry and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The diffusion coefficient of Tb(III) and the formal standard potential of Tb(III)/Tb⁰ were determined to be 2.06 ± 0.4 × 10^? 5 cm² s^? 1 and ? 2.83 ± 0.03 V vs. Cl₂/Cl^? at 887 K, respectively. Additionally, visible fluorescence of Tb(III) due to the electronic transitions from ⁵D₃ and ⁵D₄ to ⁷F_J was observed and measured by TRLFS for the first time. These results provide the first fluorescence spectroscopic evidence for a direct in situ quantification of Tb(III) in the high temperature molten salt system.     

Diffusion Coefficients in Aqueous Solutions of Ammonium Monovanadate at 25°C

Differential diffusion coefficients of ammonium monovanadate in water at 25°C and at concentrations from 0.001 to 0.05 mol-dm^–3, have been measured using a conductimetric cell and an automatic apparatus to follow diffusion. The cell uses an open-ended capillary method and a conductimetric technique is used to follow the diffusion process by measuring the resistance of solutions inside the capillaries at recorded times.     

Synergistic solvent extraction of some “4ƒ” elements from molten alkali nitrates at 160°C

Synergistic extraction of some rare earths elements Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm and Yb in (LiK)NO₃ eutectic at 160°C has been studied with the following mixtures: system I, Thenoyltrifluoroacetone (HTTA) + ethylene bis (diphenylphosphine oxide)(2DPO) and system II, hexamethylphosphorotriamide (HMPT) + (2-DPO). These different reagents were diluted in a eutectic of polyphenyls.At the maximum of the synergistic effect, the mixed extracted species are respectively Ln(TTA)₃(2-DPO) and Ln(NO₃)₃(HMPT)(2-DPO) for all the lanthanides.With these two systems, the synergistic effect is small. But with the system I, an enrichment of the organic phase in the heaver lanthanide is possible.     

Electric conductivity of kaolin in the temperature range 150–560°C

Thedc conductivity of kaolin (Sedlec and Podboany) used in electrical insulator technology was measured in temperature cycles between 150 and 560°C after preheating at 150°C/30min. The heating and cooling rates were 5°C min^–1. Dehydroxylation was accompanied by a temporary fall in thedc conductivity as a consequence of the reaction between removed OH^– groups. The changes indc conductivity over the temperatures used were explained by the migration of Ca²⁺, Na⁺ and K⁺.     

Electrochemical behavior of uranium(III) in NaCl–KCl molten salt

The electro-redox behavior of uranium(III) on Mo electrode in NaCl–KCl molten salt in the temperature range 973–1073 K has been investigated using cyclic voltammetry electrochemical method and so on, such research will help to understand uranium behavior in pyro-reprocessing. The results showed that UCl₃ could be reduced into uranium metal in a quasi-reversible one-step process exchanging three electrons. The diffusion coefficients of U(III) ions were determined and the activation energy for diffusion was found to be 55.794 kJ mol⁻¹. The apparent standard potentials of U(III)/U(0) at several temperatures were calculated. The thermodynamic properties of UCl₃ have also been investigated.

     

Dilution enthalpies of alkanols in concentrated aqueous solutions of urea at 25°C

Enthalpies of dilution of some aliphatic alcohols were determined at 25°C in aqueous 7M urea solutions by flow microcalorimetry. The excess enthalpies were expressed as power expansion series in molalities referred to 1 kg of constant composition urea-water mixture. This urea-water mixture was utilized throughout as a mixed solvent. The values of the second enthalpic virial coefficients were all found to be positive and generally lower than the corresponding values in water. Large differences were encountered, as in water, by comparing normal and branched isomeric propanols and butanols. For one system it was possible to measure the third coefficients, which were also positive. The second enthalpic coefficients were found to increase with the molecular weight of the alkanols. These facts suggest that in the presence of a large concentration of urea, the excess enthalpies are mainly determined by apolar interactions. This is surprising and potentially rich in consequences for a better understanding of the interactions among amino acid residues distantly situated in the primary sequences but topologically near in the loops of globular proteins. An analysis, carried out using the Savage-Wood additivity group method, shows that the enthalpic contributions (that appear to play a crucial role in water in making the polar interaction to be favorable) become essentially unfavorable in urea-water solvent. The hypothesis that the peptide-peptide interactions are prevented by the preferential solvation of urea is also discussed.     

Effect of pressure on the solubility of naphthalene in water at 25°C

Solubility of naphthalene in water was measured at 25°C and pressures up to 200 MPa. The solubility decreased with increasing pressure. From the pressure coefficient of the solubility, the volume change V accompanying the dissolution was estimated as 13.8±0.4 cm ³ -mol ^–1 . Further we estimated the volume change V _CH accompanying hydrophobic hydration as –0.1±0.6 cm ³ -mol ^–1 using the V value, the molar volume of crystalline naphthalene, and the partial molar volume of naphthalene in n-heptane. This V _CH is much larger (i.e., less negative) than that for hydrophobic hydration of alkyl-chain compounds and suggests that the hydration structure of naphthalene differs from that of alkyl-chain compounds.     

Oxidation of UO2 by oxygen at 66°C and 80°C

The increase in weight of uranium dioxide with time in the presence of 6–7 torr of oxygen at 66°C and 80°C was measured with a recording microbalance. At 80°C the composition of the uranium oxide was UO_2·33 after 2650 hr. At 66°C the composition reached UO_2·28 after 7400 hr. The kinetics of oxidation were described approximately by an equation for diffusion of O atoms into UO₂ spheres with diffusion coefficients of 4 × 10⁻¹⁹ cm²/sec at 66°C and 1·5 × 10⁻⁸ cm²/sec at 80°C. The coefficients are close to the values obtained by extrapolation from published data.     

Effect of oxidation of nitride coatings on corrosion properties of Ti-6Al-4V alloy in 0.9% NaCl at 40°C

The corrosion properties of Ti-6Al-4V alloy with oxidized thermodiffusion nitride coatings were investigated in isotonic 0.9% solution of NaCl at temperature of 40°C. It was shown that modification of nitride coatings by oxygen leads to a deterioration of the protective properties of nitrided surface of Ti-6Al-4V alloy. The protective properties of the alloy with nitride coatings modified by oxygen are determined by the composition of formed surface oxynitride film.