Phase and extraction equilibria in H<Subscript>2</Subscript>O–sulfonol–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) and H<Subscript>2</Subscript>O–sodium dodecyl sulfate–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) systems

Solubility isotherms of water–sulfonol–hydrochloric (or sulfuric) acid and water–sodium dodecyl sulfate–hydrochloric acid systems at 75°C and a water–sodium dodecyl sulfate–sulfuric acid system at 50°C are constructed. Regions of two-phase liquid equilibrium suitable for use in extraction are found. Concentration parameters for extraction are determined. The interfacial distribution of a series of metal ions with and without such additional complexing reagents as diantipyrylmethane and diantipyrylheptane is studied.     

Oxidation of Adamantane with H<Subscript>2</Subscript>O<Subscript>2</Subscript>–CF<Subscript>3</Subscript>COCF<Subscript>3</Subscript> · 1.5 H<Subscript>2</Subscript>O in the Presence of VO(acac)<Subscript>2</Subscript>

The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane in the presence of VO(acac)₂ to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one in a mixture of acetic acid with pyridine.     

Oxidative leaching of uranium from SIMFUEL using Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O<Subscript>2</Subscript> solution

A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr, Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na₂CO₃ solution with hydrogen peroxide. U₃O₈ was dissolved more rapidly than UO₂ in a carbonate solution. However, in the presence of H₂O₂, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO₂(O₂) _x (CO₃) _y ^2−2x−2y , where x/y has 1/2, 2/1.     

Selective removal of Cs and Re by precipitation in a Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O<Subscript>2</Subscript> solution

The removal of Cs and Re (as a surrogate for Tc) by selective precipitation from the simulated fission products which were co-dissolved with uranium during the oxidative dissolution of spent fuel in a Na₂CO₃–H₂O₂ solution was investigated in this study. The precipitations of Cs and Re were examined by introducing sodium tetraphenylborate (NaTPB) and tetraphenylohosponium chloride (TPPCl), respectively. The precipitation of Cs by NaTPB and that of Re by TPPCl each took place within 5 min, and an increase in temperature up to 50 °C and a stirring speed up to 1000 rpm hardly affected their precipitation rates. The most important factor in the precipitation with NaTPB and TPPCl was found to be a pH of the solution after precipitation. Since Mo tends to co-precipitate with Cs or Re at a lower pH, an effective precipitation with NaTPB and TPPCl was done at pH of above 9 without the co-precipitation of Mo. More than 99% of Cs and Re were precipitated when the initial concentration ratio of NaTPB to Cs was above 1 and when that of TPPCl to Re was above 1. The precipitation of Cs and Re was never affected by the concentration of Na₂CO₃ and H₂O₂, even though they were raised up to 1.5 and 1.0 M, respectively. Precipitation yields of Cs and Re in a Na₂CO₃–H₂O₂ solution were found to be dependent on the concentration ratios of [NaTBP]/[Cs] and [TPPCl]/[Re].     

Formation of solid solutions of multiferroics in the Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The sequence of phases appearance during the formation of Bi_1–xNd_xFeO₃ solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO₃ or NdFeO₃) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi_1–xNd_xFeO₃ as the final product, due to the prevalence of various interphase contacts in the starting reaction zone.     

Cyclohexane oxidation with an O<Subscript>2</Subscript>–H<Subscript>2</Subscript> mixture in the presence of a two-component Pt/C–heteropoly acid catalyst and ionic liquids

Approaches to increase the efficiency of Pt/C–heteropoly acid catalyst in a liquid-phase oxidation of cyclohexane using an O₂–H₂ mixture were studied. It was shown that small additives of ionic liquid (BMImBr, Bu₄NBr, or Bu₄NHSO₄) significantly improve the catalytic effect of the Pt/C–H₃PMo₁₂O₄₀–CH₃CN system at 35°C, by slowing the rate of side reactions resulting in water formation, increasing the rate of oxygenate formation, and inhibiting their secondary oxidation reactions. The efficiency of H₂ consumption increases from 2 to 18–25%, while the selectivity of cyclohexane conversion is 92–98%. The substitution of one or two Mo(VI) ions by V(V) in the structure of the heteropoly acid decreases these parameters. In the presence of Bu₄NHSO₄, a Pt/C catalyst can be used many times. During the reaction, the heteropoly acid present in the solution is in a reduced state under the action of the reaction medium and undergoes reversible redox transformations. The nature of the catalytic action of the studied system is explained from the viewpoint of the effect of ionic liquids on the properties of a Pt/C catalyst in activating O₂, heteropoly molybdate chemistry, and the known mechanisms of the peroxide oxidation of hydrocarbons.     

Phase formation in the system Zn(VO<Subscript>3</Subscript>)<Subscript>2</Subscript>–HCl–VOCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O

The phase and chemical compositions of precipitates formed in the system Zn(VO₃)₂–HCl–VOCl₂–H₂O at pH 1?3, molar ratio V⁴⁺: V⁵⁺ = 0.1?9, and 80°C were studied. It was shown that, within the range 0.4 ≤ V⁴⁺: V⁵⁺ ≤ 9, zinc vanadate with vanadium in a mixed oxidation state forms with the general formula Zn_xV⁴⁺ _yV⁵⁺ _2-yO₅ ? nH₂O (0.005 ≤ x ≤ 0.1, 0.05 ≤ y ≤ 0.3, n = 0.5?1.2). Vanadate Zn_xV₂O₅ ? nH₂O with the maximum tetravalent vanadium content (y = 0.30) was produced within the ratio range V⁴⁺: V⁵⁺ = 1.5?9.0. Investigation of the kinetics of the formation of Zn_xV₂O₅ ? nH₂O at pH 3 determined that tetravalent vanadium ions VO2+ activate the formation of zinc vanadate, and its precipitation is described by a second-order reaction. It was demonstrated that, under hydrothermal conditions at pH 3 and 180°C, zinc decavanadate in the presence of VOCl₂ can be used as a precursor for producing V₃O₇ ? H₂O nanorods 50–100 nm in diameter.     

Thermal studies of ZnO–B<Subscript>2</Subscript>O<Subscript>3</Subscript>–P<Subscript>2</Subscript>O<Subscript>5</Subscript>–TeO<Subscript>2</Subscript> glasses

The effect of TeO₂ additions on the thermal behaviour of zinc borophosphate glasses were studied in the compositional series (100 − x)[0.5ZnO–0.1B₂O₃–0.4P₂O₅]–xTeO₂ by differential scanning calorimetry, thermodilatometry and heating microscopy thermal analysis. The addition of TeO₂ to the starting borophosphate glass resulted in a linear increase of glass transition temperature and dilatometric softening temperature, whereas the thermal expansion coefficient decreased. Most of glasses crystallize under heating within the temperature range of 440–640 °C. The crystallization temperature steeply decreases with increasing TeO₂ content. The lowest tendency towards crystallization was observed for the glasses containing 50 and 60 mol% TeO₂. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were Zn₂P₂O₇, BPO₄ and α-TeO₂. Annealing of the powdered 50ZnO–10B₂O₃–40P₂O₅ glass leads at first to the formation of an unknown crystalline phase, which is gradually transformed to Zn₂P₂O₇ and BPO₄ during subsequent heating.     

Reaction of the [B<Subscript>10</Subscript>H<Subscript>9</Subscript>O<Subscript>2</Subscript>C<Subscript>4</Subscript>H<Subscript>8</Subscript>]<Superscript>–</Superscript> anion with C-nucleophiles

The reactions of 1,4-dioxane-substituted closo-decaborate anion ([B₁₀H₉O₂C₄H₈]^–) with metal acetylenides, diethyl malonate, ethyl acetoacetate, triethyl orthoformate, acetylacetone, and malonodinitrile were studied. The reactions were shown to be accompanied with substituent ring opening and attachment of the corresponding pendant functional group. The obtained compounds were characterized by various physicochemical methods (IR and polynuclear NMR spectroscopy, ESI mass spectrometry).     

The oxidative-dissolution behaviors of fission products in a Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O<Subscript>2</Subscript> solution

This study was carried out to investigate the characteristics of an oxidative-dissolution of fission products (FP) when uranium (U) is dissolved in a Na₂CO₃–H₂O₂ carbonate solution. Simulated FP-oxides which contained 12 components were added to the solution to examine their dissolution behaviors. It was found that H₂O₂ was an effective oxidant to minimize the dissolution of FP. For the 0.5 M Na₂CO₃–0.5 M H₂O₂ solution, such elements as Re, Te, Cs, and MoO₂ were dissolved with yields of 98 ± 2%, 98 ± 2%, 93 ± 2%, and 26 ± 3%, respectively, for 2 h. Among these components, Re, Te, and Cs were completely dissolved within 10–20 min without regard to the concentrations of Na₂CO₃, and H₂O₂ due to their high solubility in the carbonate solution with and without H₂O₂. However, MoO₂ was very slowly dissolved and its yield was 29 ± 3% for 4 h. The pH of the dissolved solution revealed the greatest influence on the dissolution yields of the FP, exhibiting the most effective pH condition in the range of 10–12 in order to create a considerable suppression of the co-dissolution of FP during the oxidative-dissolution of U.     

Induction of radiative forbidden transitions in an oxygen molecule in O<Subscript>2</Subscript>–H<Subscript>2</Subscript>O collision complexes

By the DFT/B3LYP method the equilibrium structures of oxygen complexes with water are calculated in various geometric conformations with symmetries C _2v and C _s . By the MRCI/CASSCF method potential energy surface cross-sections of the ^1.3[O₂–H₂O] complexation reaction are constructed. With taking into account the spin-orbit coupling, the forbidden transition moments a ¹Δ _g –X ³Σ _g ^?, b ¹Σ _g ⁺–a ¹Δ _g , c ¹Σ _u ^?–a ¹Δ _g , A ³Σ _u ⁺–X ³Σ _g ^? of the complexes are calculated and changes in their intensities at different geometric configurations of the complex are revealed.     

Adsorption properties of γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> as measured by gas chromatography

The adsorption properties of γ-Al₂O₃ were studied using gas chromatography. Isotherms of adsorption of n-alkanes (C₆–C₉), hex-1-ene, benzene, and isobutanol were measured within 70–100°C. The isosteric heats of adsorption and contributions to them from dispersion (Δq _dis) and specific (Δq _sp) interactions were determined for hex-1-ene, benzene, and isobutanol. Under the conditions covered, hex-1-ene molecules are adsorbed mainly on account of dispersion interactions. For the adsorption of benzene, Δq _dis is nearly twice as large as Δq _sp, while for the adsorption of isobutanol, Δq _sp is nearly twice as large as Δq _dis. At 100°C, isobutyl alcohol is chemisorbed.     

Characterization of gold supported on Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–CuO–Mn<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts obtained by thermal decomposition of aerosols

The purpose of this work was to employ the differential thermal analysis (DTA) technique to compare variations in the collapse energy of the zeolite Y crystalline structure in a fresh catalyst and in the same catalyst impregnated with nickel and vanadium. A small exothermic signal in the DTA curve at 950–1150 °C indicated the collapse of the crystalline structure. The areas of the exothermic signals in the DTA curves of the two samples indicated a reduction in the curve of the metal impregnated catalyst. These results were compared with X-ray data, leading to the conclusion that metal impregnation affects the zeolite Y crystalline structure and that the DTA technique is a potentially useful tool for measuring the integrity of zeolite Y in catalysts.     

Thermal properties of Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>–PbO–P<Subscript>2</Subscript>O<Subscript>5</Subscript> glass system

Thermal behavior of xGa₂O₃–(50 − x)PbO–50P₂O₅ (x = 0, 10, 20, and 30 mol.% Ga₂O₃) and xGa₂O₃–(70 − x)PbO–30P₂O₅ (x = 0, 10, 20, 30, and 40 mol.% Ga₂O₃) glassy materials were studied by thermo-mechanical analysis (TMA) and differential thermal analysis (DTA). Replacement of PbO for Ga₂O₃ is accompanied by increasing glass-transition temperature (263 ≤ T _g/°C ≤ 535), deformation temperature (363 ≤ T _d/°C ≤ 672), crystallization temperature (396 ≤ T _c/°C ≤ 640) and decreasing of coefficient of thermal expansion (5.1 ≤ CTE/ppm K⁻¹ ≤ 16.7). Values of Hruby parameter were determined (0.1 ≤ K _H ≤ 1.3). The thermal stability of prepared glasses increases with increasing of concentration of Ga₂O₃.     

Formation of nanocrystals in the ZrO<Subscript>2</Subscript>–H<Subscript>2</Subscript>O system

Formation of zirconia nanocrystals in the course of thermal treatment of an X-ray amorphous zirconium oxyhydroxide was studied. It was shown that the formation of tetragonal and monoclinic polymorphs of ZrO₂ in the temperature range from 500 to 700°C occurs owing to dehydration and crystallization of amorphous hydroxide. An increase of the temperature up to 800°C and higher activates mass transfer processes and, as a result, activates the nanoparticle growth and increases the fraction of the phase based on monoclinic modification of ZrO₂ due to mass transfer from the nanoparticles with the non-equilibrium tetragonal structure. Herewith, formed ZrO₂ nanocrystals with monoclinic structure have a broad size distribution of crystallites, and the average crystallite size after thermal treatment at 1200°C for 20 min is about 42 nm.     

Thermal characterisation of raw aluminosilicate glazes in SiO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–CaO–K<Subscript>2</Subscript>O–Na<Subscript>2</Subscript>O–ZnO system with variable content of ZnO

Thermal properties of raw aluminosilicate ceramic glazes in the multicomponent system of SiO₂–Al₂O₃–CaO–K₂O–Na₂O–ZnO modified by ZnO addition were studied by differential thermal analysis (DTA), dilatometry (DIL), hot-stage microscopy (HSM), X-ray diffraction and fourier transform infrared spectroscopy (FTIR). Using the method of differential thermal analysis, the ways in which zinc oxides affect the temperature of transition (T _g), crystallisation (T _c) were determined. An analysis of the DTA data obtained during thermal tests showed that an increase in ZnO content results in decreasing the T _g value. Also, the influence of ZnO on characteristic temperatures and viscosity of glazes was checked. The introduction of zinc oxide (ZnO) into the glaze composition contributes to the decrease in viscosity of such glazes. An increasing ZnO content in the glazes also causes the reduction in softening (T _s), half-sphere (T _half-sphere) and fusion (T _fusion) temperatures. The mid-infrared spectroscopy showed that the thermal properties of glazes in SiO₂–Al₂O₃–CaO–K₂O–Na₂O–ZnO system modified by addition of ZnO can be associated with the depolymerising influence of zinc ions on the structure of the tested glazes.     

Distribution of niobium and lanthanum between two immiscible melts in the system LaPO<Subscript>4</Subscript>–SiO<Subscript>2</Subscript>–NaF–Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>

The system LaPO₄–SiO₂–NaF–Nb₂O₅–Fe₂O₃ is characterized by immiscibility fields in the liquid state region. Addition of iron expands fields of immiscibility of melts and decreases the temperature of their coexistence. A fraction of 87–90% of niobium is extracted into iron silicate melt, and 92–98% of lanthanum is extracted into phosphate salt melt.     

Solid-Liquid Equilibria in the Quaternary Systems KCl–MgCl<Subscript>2</Subscript>–SrCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O and NaCl–KCl–SrCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O at 348 K

Solid-liquid equilibria in the quaternary systems KCl–MgCl₂–SrCl₂–H₂O and NaCl–KCl–SrCl₂–H₂O at 348 K were measured by the isothermal solution saturation method. The composition of the equilibrium solid phase, solubilities of salts, and densities of saturated solution in the two systems were determined. Phase diagrams, water content diagrams and solution density diagrams of quaternary systems were plotted according to experimental data. The phase diagram of the quaternary system NaCl–KCl–SrCl₂–H₂O has one invariant point, three univariant curves as the boundary of NaCl, KCl and SrCl₂ · 2H₂O. This phase diagrams were simple co-saturation type without complex salt and solid solution. For the quaternary system KCl–MgCl₂–SrCl₂–H₂O, one complex salt KCl · MgCl₂ · 6H₂O (Car) had been found in this system, consisted of five univariant curves, two invariant points and four crystallization regions of MgCl₂ · 6H₂O (Bis), KCl, SrCl₂ · 2H₂O and KCl · MgCl₂ · 6H₂O. And the densities transformation rules were simply discussed. Simultaneously, the solubilities and densities data in invariant point of the quaternary system NaCl–KCl–SrCl₂–H₂O had been compared with the experimental data of previous researchers.     

Glass Formation in the Ternary System La<Subscript>2</Subscript>O<Subscript>3</Subscript>–As<Subscript>2</Subscript>S<Subscript>3</Subscript>–Er<Subscript>2</Subscript>O<Subscript>3</Subscript>

The boundaries of the glass formation region in the ternary system La₂O₃–As₂S₃–Er₂O₃ were found. Transparent glass of composition (La₂O₃)_0.03(As₂S₃)0.90(Er₂O₃)0.07 was studied by X-ray photoelectron and Raman spectroscopy. The intensities of the bands characterizing As–S, La–O, and Er–O bonds increased, and these bands were shifted toward higher energies. This was due to an increase in the covalence of these bonds and probably due to the formation of new bonds in the glasses. Samples in the glass formation region are resistant at 300 K to air, water, and organic solvents.