卷 91, 编号 7 (2017)

A critical analysis of experimental and theoretical data on the structure and vibrational frequencies of gaseous VOX₃ vanadium oxotrihalides is performed. The values of molecular constants are selected and the thermodynamic functions are calculated within a “rigid rotator–harmonic oscillator” approximation. Equations that approximate a temperature dependence of heat capacity within the temperature range of 298.15–3000 K are obtained. Analysis of the available experimental data allows the enthalpy of formation to be determined for gaseous VOCl₃ molecules. The enthalpies of formation for VOF₃, VOBr₃, and VOI₃ molecules are determined for the first time using this value and quantum-chemical calculations of energy of exchange reactions involving VOCl₃. The obtained results are added to the database of the IVTANTERMO software.

The solid-phase equilibria and thermodynamic properties of an As–Se system are studied using the electromotive force (EMF). The existence of compounds As₂Se₃, AsSe, and As₄Se₃ in a system with near constant composition is confirmed. The relative partial molar functions, standard Gibbs free energies, enthalpies of formation, and standard entropies of As in the alloys are calculated using EMF measurements.

First time we report the synthesis, structural characterization and thermal behavior of an unusual N₃⁻ containing alumino-silicate sodalite mineral. Azide sodalite, Na₈[AlSiO₄]₆(N₃)₂ has been synthesized under hydrothermal conditions at 433 K in steel lined Teflon autoclave. The structural and microstructural properties of azide sodalite mineral was characterized by various methods including FT-IR, XRD, SEM, TGA, and MAS NMR. Crystal structure have been refined by Rietveld method in \(P\bar 43n\) space group, indicating that the N₃⁻ sodalite has cubic in lattice. High temperature study was carried out to see the effect of thermal expansion on cell dimension (a^o) of azide sodalite. Thermal behavior of sodalite was also assessed by thermogravimetric method.

The kinetics of ozonolysis for a number of plant materials (aspen and pine sawdust, wheat straw, flax chaff, and sunflower husks) is comparatively studied, and the dependences of the rate of ozone absorption on the water content in lignocellulosic samples are obtained. The kinetic curves of water absorption by different plant materials in a saturated water vapor atmosphere at room temperature are constructed, and the equilibrium values of water content are determined. It is shown that straw is characterized by a higher affinity for water than wood. The range of the moisture contents of lignocellulosic materials that ensures the maximum rate of their reaction with ozone is found. No appreciable effect of the nature of plant material on the rate of ozone absorption was detected, since the process is controlled by the diffusion of ozone in the pores of materials.

Changes in the chemical composition of condensed products upon switching from synthesis in the self-ignition mode to combustion synthesis is studied by approximate analytical and numerical means for condensed substances that react via competing reaction pathways. It is shown that these different modes of synthesis produce different compositions of the reaction products. The conditions required for transitioning from one mode of combustion initiation (thermal explosion) to another (ignition) are determined. It is found that this transition can occur upon changing the temperature of a heater by just two characteristic intervals. A scaling procedure that allows the calculation results obtained at zero dimensionless temperature of the heater to be used to determine the effect its non-zero dimensionless temperature has on the ignition mode and the composition of the obtained products is proposed. Calculations show that materials with different distributions of the chemical composition along the sample can be obtained by deliberately changing the temperature of the heater.

The composition of nitric acid solutions is investigated by means Raman spectroscopy (RS). The results are compared to critically selected data from other authors. The value of the thermodynamic dissociation constant in an aqueous nitric acid solution at 25°C (K_a = \(\left[ {{H^ + }} \right]{\left[ {NO_3^ - } \right]_{\gamma '}}_ \pm ^2/\left[ {HN{O_3}} \right]{\gamma '_{HN{O_3}}}\) = 35.5 ± 1.5M) is determined by analyzing an extensive set of reliable and consistent literature and original data. Expressions for the dependences of the activity coefficient of undissociated HNO3 molecules (\({\gamma '_{HN{O_3}}}\) ) and the mean ionic coefficient (\({\gamma '_ \pm } = \sqrt {{{\gamma '}_H} + {{\gamma '}_{NO_3^ - }}} \) ) on the stoichiometric concentration of nitric acid in the range of 0–18 M are found.

Thermodynamic functions Δ_rH, Δ_rG, and TΔ_rS of the complex formation between Cu²⁺ and triglycine in water–ethanol solutions are calculated on the basis of calorimetric data. It is found that raising the concentration of EtOH results in a monotonic increase in the exothermic effect of [CuHL]²⁺ complex formation due to the weakening of triglycine solvation with the mutual compensation of ion solvation contributions. The enthalpy of [CuL]⁺ complex formation has an exothermic maximum at 0.1−0.3 molar fractions of EtOH due to competition between the solvation contributions from ions and ligands.

Some of the parameters and equilibrium constants of quaternary salts solutions KBr–K₂SO₄–K₂B₄O₇–H₂O and NaBr–Na₂SO₄–Na₂B₄O₇–H₂O at 298 K are calculated using the correlation equation of the Pitzer parameters. The solubilities data of the ternary subsystems were fitted by multiple linear regression method. The phase diagram was plotted. A comparison between the calculated and experimental results for the systems shows that the predicted solubilities agree well with experimental data.

The transfer properties and microscopic structures of methanol, ethanol, 1-propanol, 2-propanol, and 1-pentanol in the temperature range from 290 to 450 K and pressure range from 0.1 to 200 MPa were studied by molecular dynamics (MD) simulation through the calculation of the self-diffusion coefficients, velocity autocorrelation functions (VACF), and radial distribution function (RDF). The calculated self-diffusion coefficients conform to the experimental values on the whole, and the temperature has greater influence, which weaken with the increase of the carbon chain, on self-diffusion coefficient than pressure. The factors affecting self-diffusion coefficients were also analyzed from micro perspective by calculation of VACF and RDF, which is helpful to understand the relationship between microscopic structures of fluid and its transfer properties. This work not only provides a reliable simulation method for transfer properties of alkanols, but also provides the prediction data for design and development of chemical processes.

The results from investigating the surface characteristics of liquid sodium, potassium, and four potassium–sodium alloys are considered. The Auger spectra and profiles of metal droplets with atomically pure surfaces in the solid and liquid state are studied under the same experimental conditions. It is shown that potassium is a surfactant with respect to sodium at the temperature of an experiment in the investigated range of volume concentrations. It is noted that the obtained values of surface tension are 15% higher than the reference values.

The results from thermodynamic and quantum-chemical studies of the reversible reaction between (5,10,15,20-tetra(2-methoxyphenyl)porphinato)chloroindium(III) and pyridine are reported. The main physicochemical parameters of properties of its supramolecular products are obtained and analyzed. The addition of pyridine molecules to metalloporphyrin proceeds in one step to attain an equilibrium state with the formation of supramolecules with a stoichiometry of 2: 1; spectral characteristics and parameters of the stability of the latter are identified. The possibility of using substituted indium(III)porphyrin for further research in the field of hybrid solar cells is discussed.

Ionic solvation in solutions of lithium tetrafluoroborate (LiBF₄) in propylene carbonate (PC) + dimethyl sulfoxide (DMSO) mixtures has been studied using Fourier transformed infrared (FTIR) spectroscopy. Dimerization of DMSO molecules in the solutions was taken into account. The obtained results are discussed with respect to the electrolyte concentration and properties of the cations of the electrolyte. Band changes due to solvation interaction were detected in the region of the C=O stretching vibrations and ring deformation for PC, and the S=O stretching vibrations and C–S–C skeleton stretching modes for DMSO, indicating that there is a strong interaction between lithium cations and solvent molecules. In addition, Li⁺ was preferentially solvated by DMSO in these binary solvents as a result of the large difference in their donor number (DN) values. The structures of PC, DMSO, Li⁺-PC, Li⁺-DMSO, and Li⁺-PC+DMSO were given.

A series of silver-containing composites based on highly hydrophilic silica S-120, moderately hydrophilic activated carbon, and hydrophobic copolymer of styrene with divinylbenzene (Psb-1) is synthesized and studied using nonlinear gas chromatography, XRD, IR spectroscopy, and volumetric adsorption, and by optical means. The effect modifying an adsorbent with silver nanoparticles has on the structure, geometry, and chemistry of its surface, and the effects the concentration of metal, the nature of the matrix, the means of synthesis, and the size of nanoparticles have on its adsorption and catalytic properties, are studied. The surface plasmon resonance (SPR) effect is observed in some composites.

The sorption of acetone from the vapor phase by Keplerate polyoxomolybdate (POM) nanoclusters, Mo₁₃₂ and Mo₇₂Fe₃₀, and Mo₁₃₈, a POM with a toroid structure, is studied via equilibrium interval sorption (a modification of vapor sorption gravimetry). The highest sorption capacity is registered for Mo₁₃₂, while the other two show performance an order of magnitude lower. The specific Gibbs energy of the interaction between the POMs and acetone is reported. Small-angle X-ray and neutron scattering analysis indicates a considerable difference between the natures of Mo₁₃₂ and Mo₁₃₈ surfaces.

The immobilization of fluorinated tetraphenylporphyrins (FTPPs) into tetrafluoroethylene copolymers (fluoroplast F-42 and MF-4SK, a perfluorinated sulfonic acid cation exchanger in H⁺-form) is conducted in supercritical CO₂ (scCO₂). The effects the conditions of immobilization (the temperature and pressure of scCO₂, reaction time, and the addition of cosolvents) and the structure of the carrier polymer have on the content of porphyrin in these polymers is studied. The porphyrin-loaded polymer systems are shown to exhibit photosensitizing activity in anthracene and cholesterol oxidation in scCO₂. Under conditions of photocatalysis, chemical and functional stability is a feature of only MF-4SK polymer systems; this is attributed to the formation of protonated forms of the porphyrins and their interaction with SO₃⁻-groups of the polymer (an ion exchange process), which prevents leaching of the FTPP from the polymer matrix. The photocatalytic process actually occurs inside the matrix of the perfluorinated copolymer, with the protonated form of the porphyrin acting as a photosensitizer. The rate constant of anthracene photooxidation in the presence of FTPP-loaded MF-4SK films in scCO₂ is found to pass through a maximum as a function of the porphyrin content and the polymer film thickness. The use of such catalytic systems for cholesterol photooxidation in scCO₂ is shown to produce a virtual monoproduct (yield, ~10%): 6-formyl-B-norcholestane-3,5-diol, a compound with high biological activity.

The possibility of the electroprecipitation of copper powder via the cathodic reduction of an electrolyte solution containing copper(II) nitrate trihydrate and dimethyl sulfoxide (DMSO) is shown. The effect electrolysis conditions (current density, concentration and temperature of electrolyte) have on the dimensional characteristics of copper powder is studied. The size and shape of the particles of the powders were determined by means of electron microscopy; the qualitative composition of the powders, with X-ray diffraction.

Several up-conversion luminescent materials (Er³⁺:Y₃Al₅O₁₂, Yb doped Er³⁺:Y₃Al₅O₁₂, Yb and N co-doped Er³⁺:Y₃Al₅O₁₂, Yb and F co-doped Er³⁺:Y₃Al₅O₁₂, and Yb, N, and F co-doped Er³⁺:Y₃Al₅O₁₂) were synthesized using sol–gel method. The corresponding TiO₂ composite films (Er³⁺:Y₃Al₅O₁₂/TiO₂, Yb doped Er³⁺:Y₃Al₅O₁₂/TiO₂, Yb and N co-doped Er³⁺:Y₃Al₅O₁₂/TiO₂, Yb and F co-doped Er³⁺:Y₃Al₅O₁₂/TiO₂, and Yb, N, and F co-doped Er³⁺:Y₃Al₅O₁₂/TiO₂) were prepared by sol–gel dip-coating method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). The UV–Vis absorption and PL spectra of Er³⁺:Y₃Al₅O₁₂ were also determined. The visible-light photocatalytic activity of the synthesized materials was evaluated in the degradation of Azo Fuchsine (AF) dye in aqueous solution. The concentration of the dye was monitored by UV–Vis spectroscopy. Some key factors, such as layer number, heat-treatment temperature and time on the photocatalytic activity of Yb, N, and F co-doped Er³⁺:Y₃Al₅O₁₂/TiO₂ composite films were studied. The doping of Yb, N, and F into Er³⁺:Y₃Al₅O₁₂/TiO₂ significantly enhanced the visible-light photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/TiO₂ composite film in the degradation of organic dyes. The experiments also indicated that the Yb, N, and F co-doped Er³⁺:Y₃Al₅O₁₂/TiO₂ composite film has a good visible-light photocatalytic activity to degrade other organic dyes under visible-light irradiation.

It is shown that mechanisms of photoreactions, investigated using the effects of chemically-induced dynamic nuclear polarization (CIDNP), can serve as models of primary electron transfer during photosynthesis from sensitizers (chlorophyll or porphyrin) to acceptors (membrane-associated quinone in media with different polarities).