Vol 90, No 8 (2016)

A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor–fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

The enthalpy of dissolution of sesquiterpene lactone grossheimin C₁₅H₁₈O₄ is measured using a DAK-I-IA calorimeter at a lactone/ethanol (96%) molar ratios equal to 1 : 18000, 1 : 36000, and 1 : 72000. The standard enthalpy of dissolution of grossheimin in a 96% ethanol solution is calculated based on the resulting data. The temperature dependence of the heat capacity of grossheimin C_p^° ∼ f (T) is studied by means of dynamic calorimetry using a IT-C-400 device in the temperature range of 298.15–423 K. An equation describing this dependence is derived. The standard enthalpies of combustion, melting, and formation of grossheimin are calculated using approximate methods.

Heats of solution of crystalline α-aminobutyric acid in water and in aqueous solutions of potassium hydroxide at 298.15 K are measured by means of direct calorimetry. Standard enthalpies of formation of the amino acid and products of its dissociation in an aqueous solution are calculated.

The process of butene-1 isomerization in the presence of two groups of samples of zeolite-containing catalyst (ZCC) that earlier participated in the traditional and oxidative catalytic cracking of vacuum gasoil is investigated. It is established that the nature of the reaction mixture and conditions of the cracking process are key factors in forming the acidic and basic properties of the catalyst. It is shown that the highest activity in the butene-1 isomerization into cis-/trans-butene-2 is demonstrated by ZCC samples that participated in the oxidative catalytic cracking (oxycracking). It is suggested that the enhanced catalytic activity of this group of ZCC samples was related to the availability of acid–base centers in the form of radical-like oxygen along with protic- and aprotic-type acidic centers in the structure of the oxidative compaction products.

Various Ta-HMS (hexagonal mesoporous silica) samples with different Ta content were hydrothermally prepared and characterized by XRD, N₂-adsorption, ICP-AES, FTIR, and UV–Vis spectroscopy. The catalytic performance of the samples was also evaluated in the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. The regularity of mesoporous structure decreases while more extraframe Ta ions are formed with increasing the Ta content. Ta-HMS with Ta/Si ratio of 0.015 shows the highest conversion and selectivity in the studied epoxidation reaction. The catalyst can be used for three times without significant activity loss.

Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb²⁺, Cu²⁺, Mn²⁺, Zn²⁺. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb²⁺ ion was 99.97%. The mechanism of Pb²⁺ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

The effect the degree of hydration has on optical and electrophysical properties of water/AOT/n-hexane system is studied. It is found that AOT reverse micelles form aggregates whose dimensions grow along with the degree of hydration and temperature. Aggregation enhances their electrical conductivity and shifts the UV spectrum of AOT reverse emulsions to the red region. Four states of water are found in the structure of AOT reverse micelles.

The phase equilibria in the binary diphenyl–n-dodecane and ternary diphenyl–diphenyl oxide–n-dodecane systems was studied by differential scanning calorimetry. The melting temperatures and eutectic compositions were determined. The physicochemical characteristics of eutectic alloys such as the flash point, density, and enthalpy of fusion were given. The kinematic viscosity of eutectic alloys was determined in the temperature range 25–50°C.

Phase equilibria in layering systems of water, polyethyleneglycol ethers of monoethanolamides of synthetic fatty acids (SFAs) (synthamide-5), and ammonium chloride are studied. The possibility of using such systems for the liquid extraction of metal ions is evaluated. The effect the nature of salting-out agents has on the processes of segregation of the systems has been considered.

The boiling points of solutions of five binary systems are measured via ebulliometry in the pressure range of 2.05–103.3 kPa. Equilibrium vapor phase compositions, the values of the excess Gibbs energies, enthalpies, and entropies of solution of these systems are calculated. Patterns in the changes of phase equilibria and thermodynamic properties of solutions are established, depending on the compositions and temperatures of the systems. Liquid–vapor equilibria in the systems are described using the equations of Wilson and the NRTL (Non-Random Two-Liquid Model).

The optimized geometries and interaction energies of the intermolecular heterodimers of coronene with o-, m-, and p-dimethylbenzenes (xylenes) calculated by DFT in the PBE0 and B97D functionals were compared. The applicability of coronene as a model for qualitative assessment of the interaction of mononuclear aromatic compounds with the graphite surface was demonstrated. The necessity of including long-range dispersion interactions in DFT calculations of the dimerization energies of aromatic systems was shown. The sorption enthalpies of p- and m-xylenes were shown to be almost equal irrespective of the conditions of the chromatographic experiment. The preferred sorption of p- over m-xylene on graphite is solely due to the entropy factor.

The complex rose-like inorganic templates assembled by the ZnO/ZnO₂ hybrid nanosheets have been constructed with hydrogen peroxide as an additive to control the structure of a precursor. The surface morphologies of the inorganic templates can be controlled by varying the reaction time and the amount of hydrogen peroxide. The process of the precursor growth takes a dissolution-growth route under hydrothermal conditions. The chemical composition of the precursor is determined by X-ray diffraction (XRD) and Raman analyses, indicating the existence of peroxide in the precursor. Combined with transmission electron microscopy (TEM) data, the ZnO/ZnO₂ hybrid precursor is proposed to act as an inorganic template for the growth of secondary crystal structures. The dandelion-like ZnO crystal is fabricated by using rose-like peroxide precursor as the inorganic template. The structural evolution of hierarchical ZnO crystal is studied by monitoring the influence of the reaction time.

The micromechanical properties (Young’s modulus, deformation, and adhesion) of the intercalated compound of graphite oxide with dodecahydro-closo-dodecaboric acid were studied by atomic force microscopy, transmission electron microscopy, and Raman spectroscopy and compared with the same characteristics of the starting graphite oxide. The significant difference in the micromechanical properties of the materials under study is dictated by differences in the topography and properties of their film surface, which, in turn, can be determined by their chemical composition. The introduction of dodecahydro-closo-dodecaboric acid in the interplanar space of graphite oxide affects the structuring of the latter. A considerable increase in the adhesion of the intercalated compound relative to that of oxide graphite is explained by high adhesive properties of the introduced acid, the Young’s modulus of graphite oxide being higher than that of the intercalated compound. This was attributed to the high hydrophilicity of dodecahydro-closo-dodecaboric acid and the difficulty of water removal from the interplanar space; water plasticizes the material, which becomes softer than graphite oxide. The difference in the structure of the coating of the intercalated compounds and the starting graphite oxide was found to be also reflected by their Raman spectra, namely, by the increased intensity of the D line with the preserved position of the G line, which points to the impurity nature of the intercalate and the unchanged hexagonal lattice of graphite.

The effect the conditions of thermal treatment have on a specific surface and the number of primary adsorption centers is studied. The relationship between changing adsorption characteristics and changes in the structure of nanofibrous aluminum oxide is considered.

NMR spectroscopy, NMR relaxation, and NMR with a pulsed magnetic field gradient methods are used to study the swelling of the elastomers based on ethylene-propylene rubber, butadiene-nitrile rubber, and fluororubber SKF-26 in transformer oil. Components corresponding to the fractions of oil and polymer network are identified. It is shown that the affinity of the polymers toward transformer oil displays an increase in the orderly sequence of ethylene-propylene rubber, fluororubber, and butadiene-nitrile rubber; the stability of the polymers towards carbon tetrachloride falls in the same sequence. Based on an analysis of the spin–spin relaxation time depending on the degree of swelling, it is found that fluororubber elastomers are characterized by the formation of a polymer network that prevents further sorption, In contrast, elastomer based on ethylene-propylene rubber gives no indication of the formation of a rigid polymer network.

The volume ratios in acetonitrile–ethyl acetate (90 : 10, 95 : 5), acetonitrile–isopropanol–ethyl acetate (70 : 15 : 15, 80 : 5 : 15), and isopropanol–1-butanol (50 : 50) mixtures were determined. Their mixing with water (1 : 1) and storage at–10°C led to partitioning into two immiscible liquid phases without formation of the ice phase. The mixtures were shown to be useful as hydrophilic extractants in low-temperature liquidliquid extraction of phenol from aqueous solutions.

A new effect leading to the slowing of recombination in a weakly nonideal ion plasma is considered. The solvation of ions is included in the explanation of the results from studying a gas discharge afterglow in a fluorine atmosphere. It is shown that recombination in such a system is slowed in comparison to the standard relationships for ideal plasma. The formation and composition of cluster ions in such a medium are considered. The relationship between the variation in the kinetics of recombination and the course of the process according to a complicated mechanism with the intermediate formation of metastable cluster pairs is established. A quantitative model is built and a formula allowing us to describe the recombination rate over a wide range of parameters of the medium is obtained. It is shown that the proposed model is in good agreement with the experimental data.

The content of oxygen in Ca_1−xPr_xMnO_3−δ (x = 0.1) material with perovskite-like structure is determined at 750–950°C and oxygen partial pressures in the gas phase from 3 × 10⁻⁶ to 0.55 atm. The regions of existence of orthorhombic, tetragonal, and cubic structural modifications are determined. The equilibrium constants, enthalpies, and entropies of reactions of the formation of defects are determined, allowing us to describe the experimental δ (\({p_{{O_2}}}\),Т) dependences accurately and calculate the concentrations of manganese ions. It is shown that a change in Ca_0.9Pr_0.1MnO_3–δ structure has a considerable effect on the thermodynamic functions of reactions of the formation of defects.

We developed a method to improve the performance of the copper phthalocyanine (CuPc)/fullerene (C₆₀) organic solar cells (OSCs) by doping CuPc with a long triplet lifetime material. By doping [Cu(bis[2-(diphenylphosphino)phenyl]ether)(benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine)]BF₄ (CuDB) into CuPc, the enhanced short-circuit current density (J_SC) of 6.213 mA/cm², open-circuit voltage (V_OC) of 0.39 V and a peak power conversion efficiency (PCE) of 0.92% compared to 0.79% of the standard CuPc/C₆₀ OSCs are achieved under 1 sun AM 1.5 G illumination at an intensity of 100 mW/cm². The performance improvement is mainly attributed to the long triplet lifetime of CuDB (τ = 70.05 μs) which leads to more effective exciton dissociation.

The thermodynamic characteristics of sorption of 24 organic compounds of various classes from the gas phase on the binary stationary phase based on polyethylene glycol 400 and permethylated β-cyclodextrin were determined. The influence of geometrical structure and optical activity of organic compounds on the possibility of forming sorbate–macrocycle complexes was examined. It was found that the studied stationary phase shows the enantioselectivity towards low-polar terpenes under the conditions of gas chromatography.