# Russian Journal of Physical Chemistry B

## Current research reports and chronological list of recent articles..

The Focus on Physics the scientific Russian Journal of Physical Chemistry B publishes original and review papers relevant to all aspects of chemical physics. Elementary chemical and physical processes on the molecular level are considered.

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## Russian Journal of Physical Chemistry B - Abstracts

Energy Production and Recovery of Rare Metals from Ash Residue During Coal Filtration Combustion

### Abstract

The results of studies on the extraction of vanadium, nickel, and cobalt compounds from ash residue obtained in the process of the filtration combustion of charcoal and brown coal with subsequent hydrometallurgical extraction of metals from ash residues are presented. Coals with metal salts preliminarily deposited on them are used for the research. The regularities of gasification of the studied coals (temperatures and combustion rates) are studied and it is shown that the heat of combustion of gaseous products for both types of coals is 4.3–4.5 MJ/m3. Using X-ray phase analysis, the crystal structures of metal compounds in ash residues are determined. Metal compounds are leached from the ash residue with water, acids, hydrogen peroxide, and their mixtures. It is established that vanadium compounds almost completely turn into a solution during leaching with acid solutions. At the same time, the maximum degree of extraction of nickel and cobalt from the ash residues of gasification does not exceed, respectively, 59 and 61% for charcoal and 40 and 28% for brown coal. This is due to the fact that nickel and cobalt compounds are present in ash residues, which are resistant to the action of aqueous solutions of acids and other oxidizing agents.

Datum: 01.04.2022

Autowave Synthesis of Cast Iron Aluminide Fe2Al5 from a Thermite Type Mixture

### Abstract

This study shows the possibility of obtaining cast iron aluminide Fe2Al5 in the mode of autowave synthesis from a thermite type mixture at atmospheric pressure in air. The study shows that mixtures of Fe2O3–α-Al burn in a wide range of reactant ratios, and their combustion temperature allows gravitational separation of the combustion products and production of cast iron aluminides. The chemical and phase compositions, microstructure, and microhardness of the synthesized iron aluminide are studied.

Datum: 01.04.2022

Structure and Properties of Films and Coatings Made of a Styrene-Butadiene Thermoplastic Elastomer

### Abstract

This study is devoted to the establishment of the connection of antibacterial surface properties with the structure and composition of coatings based on a styrene-butadiene thermoplastic elastomer with polylactide and antibacterial agents: tetramethylenediethylenetetramine or distearyldimethylammonium chloride. It is shown that the mechanism of antibacterial action of the composition is based on the leaching (release) of antibacterial agents in an aqueous environment together with microorganisms. The effect depends on the structural organization of the coating, which accelerates their leaching and is enhanced by the inclusion of antibacterial agents in the hydrolyzed phase of the polylactide, which is localized in the styrene-butadiene matrix around the polystyrene domains. The features of the structure of the films and coatings are established by scanning electron microscopy (SEM), using a paramagnetic probe, physical and mechanical parameters, and by studying the laws of thermal destruction using thermogravimetry.

Datum: 01.04.2022

Change in the Ignition Parameters of Nanodispersed Iron Powders During Long-Term Storage

### Abstract

In this paper, the ignition of samples pressed from nanodispersed iron powder with nanosized particles, stored after manufacturing for four years, is studied. The ignition temperature of samples pressed from an initially pyrophoric powder with the average particle diameter of 85 nm was about 105°C. As a result of the oxidation and agglomeration of the powder during long-term storage in air, the ignition temperature increased to 225°C. The ignition temperatures of nanodispersed iron powder and iron powders with average particle sizes of 3, 4.6, and 55 µm are compared. The possibility of partial restoration of the reactivity of such iron powders after their annealing in argon is shown.

Datum: 01.04.2022

Mechanical and Rheological Properties of Biocomposites Based on Polyethylene and Keratin

### Abstract

The mechanical and rheological properties of biocomposites based on polyethylene (PE) and keratin obtained by high-temperature shear deformation using an extruder-dispersant and by mechanical mixing in a Brabender plastograph are investigated. It is established that the method of high-temperature shear deformations makes it possible to obtain stronger materials. The biodegradation process of PE–keratin mixtures with different contents and dispersions of the filler is studied. It is found that the most intensive biodegradation process occurs in compositions obtained using an extruder-dispersant.

Datum: 01.04.2022

Physical and Chemical Properties, Composition and Thermal Stability of a Complex of Neodium(III) with Heparin

### Abstract

The complex formation of Nd(III) with heparin anions is studied by pH-metric titration at 37°C (supporting electrolyte 0.15 M NaCl). The formation constant (β) of the complex [NdHep]: log  β(NdHep) = 4.28 ± 0.02) is calculated using the NewDALSFEK program. The complex [Nd(H2O)3Hep]n is isolated in a solid form. Its composition is determined by the results of an X-ray spectral electron probe analysis, thermogravimetry, differential scanning calorimetry, and IR spectroscopy.

Datum: 01.04.2022

Modification of Boron Powders Used in Energy-Saturated Materials

### Abstract

The structural and morphological properties of powders of commercial amorphous boron grade B modified with acetonitrile, weak nitric acid, and fluorine-containing compounds are studied by the Brunauer, Emmett and Teller (BET), scanning electron microscopy (SEM), and Raman spectroscopy methods. The influence of these properties on the oxidation of powders is analyzed using thermogravimetric analysis (TGA). It is shown that the removal of the surface layer in the form of boron oxide and boric acid leads to a more complete oxidation degree of the powder.

Datum: 01.04.2022

Interaction of Gases with Single Clusters of Gold and Copper-based Nanoparticles in the Presence of Electric Fields

### Abstract

The interaction of CO and H2 with single clusters of gold and copper-based nanoparticles in the presence of an electric field has been studied. It is shown that depending on the direction of the electric field vector, the adsorption of molecules from the gas phase is stimulated or inhibited. Mechanisms of influence of the field on chemical processes are proposed.

Datum: 01.04.2022

Structure and Dynamics of the Combustion Front of a Lean Hydrogen-Air Mixture in a Flow-Through Reactor

### Abstract

The dynamics of the development of the combustion front of a preliminarily mixed and depleted hydrogen-air mixture in a flow-through reactor (channel) of various widths are considered by numerical simulation methods, and the structure of the combustion front is analyzed. Based on the calculations performed, the dependence of the flame front’s propagation velocity on the front’s expansion is established in a wide range of hydrogen concentrations in the combustible mixture. It is shown that for all the compositions considered, the dependence of the flame’s acceleration due to the increase in the combustion front’s surface is linear at high expansion values and nonlinear at low expansion values. In this case, with a decrease in the hydrogen concentration in the mixture, the nonlinear section manifests itself more strongly, which determines a more intense increase in the flame velocity with expansion for lean mixtures.

Datum: 01.04.2022

Effect of Spontaneous Fluctuations on the Origin and Development of Turbulence: 2. Features of the Evolution of an Unstable System

### Abstract

The equations of multimoment hydrodynamics are used to study the process of distortion of regular flow modes in the problem of a flow around a sphere at rest. The effect of spontaneous fluctuations, which are constantly present in the medium, regardless of the external effect, is studied. It is shown that the behavior of an unstable system is a mirror image of its behavior in the stability mode. The change in the direction of evolution of a system that has lost stability excludes the possibility of the participation of spontaneous fluctuations in the occurrence and development of turbulence. Thus, this responsibility falls entirely on the disordered perturbations that appear in the environment due to an external effect. In the absence of disordered perturbations, spontaneous fluctuations ensure the fulfillment of conservation laws in a system that has lost stability. However, spontaneous fluctuations are not able to distort the laminar flow pattern in the wake of the sphere.

Datum: 01.04.2022

Theoretical Investigation of Gasification of Solid Fuel in a Low-Temperature Gas Generator of an Aircraft

### Abstract

The mathematical model and numerical method proposed in this study make it possible to study the regularities of gasification of solid porous fuel when hot gases are filtered through it and estimate the maximum operating time of the propulsion system. The features of gasification are studied for the case when polymethyl methacrylate is used as a solid fuel. It is shown that by changing the characteristics of the system and the process conditions, it is possible to change the flow rate of gaseous products from the gas generator, which will affect both the operating conditions of the cooling system for the materials of the combustion chamber structure and the value of the engine thrust. It is also shown that the operating time of a jet engine with a low-temperature gas generator increases with decreasing temperature and consumption of gaseous solid fuel combustion products, the interphase heat transfer coefficient, and the characteristic pore size of the fuel.

Datum: 01.04.2022

Features of the Use of Polyelectrolytes to Prolong the Action of Medicinal Substances

### Abstract

This paper is devoted to studying the features of the release of medicinal substances (MSs, drugs) (both electrolyte and non-electrolyte) from solutions of polyelectrolytes through a semipermeable membrane. Polycation chitosan and polyanion sodium salt of chitosan succinyl are used as polymers, and cefazolin (CFZ) sodium salt, lidocaine hydrochloride (LH), and dioxidine (DO) are used as MSs. In the course of the study, the fact of the interaction between polyelectrolytes and drugs and the influence of the conformational and supramolecular state of polymers in a solution on the values of diffusion coefficients for the release of drugs from polymer solutions through a semipermeable membrane are established. It is shown that the interaction between drugs and polyelectrolytes has a number of characteristic features due to the ionogenic nature of the polymers used and the manifestation of the conformational-supramolecular effect. These features lead to the fact that a significant difference in the amount of the drug firmly retained by the polymer chain and the values of the diffusion coefficients of its release appear only in the region of dilute solutions. Upon transition to the region of semidilute solutions, due to changes in the structure of polymers in solution, these differences mitigated, which is accompanied by convergence of the diffusion coefficients for the release of various of kinds of drugs from polymer solutions through a semipermeable membrane.

Datum: 01.04.2022

The Mechanism of the Influence of an Additional Turbulence Source in the Flow-Through Combustion Chamber on the Combustion Mode of a Rich Mixture of Natural Gas With Oxygen

### Abstract

The experimental parameters are obtained for two modes of combustion of a premixed flow of a rich mixture of natural gas with oxygen in a chemical reactor with an increased heat density of its flow-through combustion chamber in the absence and presence of an additional intrachamber source of turbulence. Mathematical modeling of kinetic combustion in a plug-flow-through reactor with the same initial and output parameters of the stationary modes as in the experiments qualitatively reveals the mechanism of the effect of an additional flow turbulizer on the experimental combustion modes.

Datum: 01.04.2022

Effect of Heat Losses on the Propagation of Cellular Waves in the Filtration Combustion of a Layer of Titanium Powder

### Abstract

The unstable propagation of combustion of a layer of titanium powder in horizontal and inclined channels under conditions of natural gas filtration is experimentally studied. The critical conditions for the disruption and restructuring of the combustion modes with an abrupt change in heat loss during the combustion of a layer on an inert substrate of variable composition is analyzed. The influence of the convective removal of impurity and inert gases on the processes of the passage of the combustion front over the boundary of dissimilar substrates is studied. The results are interpreted in the model of the heat-filtration stability of combustion in porous media.

Datum: 01.04.2022

Simulation of Hydrogen Adsorption on AunNim, AunCum, and CunNim Clusters; n + m = 13

### Abstract

This paper presents the results of quantum chemical modeling of hydrogen atom adsorption on AuNi, AuCu, and CuNi bimetallic nanoparticles. It is established that changes in the electronic structure of these clusters depend both on the transformation of the atomic structure of the cluster and on charge transfer. The effect of charge transfer manifests itself most noticeably in clusters consisting of atoms with slightly different lattice constants Cu and Ni. With strong differences in this parameter, changes in adsorption properties will be determined to a greater extent by the transformation of the atomic structure.

Datum: 01.04.2022

Initial Stages of The Ignition of Coal Microparticles of Different Grades by Laser Pulses

### Abstract

The emission spectra of coal particles ≤63 μm in the the metamorphism rank from long-flame to anthracite are studied during exposure to a laser pulse (τi = 120 µs). The threshold value of the laser pulse density, $$H_{{{\text{cr}}}}^{{\left( 1 \right)}},$$ at which it becomes possible to detect the emission of coal particles by instruments, is related to the ignition of reactive microprotrusions on the surface of the coal particles. At an energy density of H = $$H_{{{\text{cr}}}}^{{\left( 2 \right)}}$$ , the surface of the coal particles is sufficiently heated to initiate chemical reactions in their volume, as well as the release and ignition of volatile matter, through a heterogeneous ignition mechanism. As the energy density increases to H > $$H_{{{\text{cr}}}}^{{\left( 3 \right)}}$$ the chemical processes in the coal particles are similar to the processes occurring during H = $$H_{{{\text{cr}}}}^{{\left( 2 \right)}},$$ but with the increase in H, the intensity of the emission and, consequently, the rate of chemical reactions in the coal particles increase during the action of the laser pulse. In the spectra at all stages of ignition, the emission of $${\text{CO}}_{2}^{*}$$ (CO flame), excited molecules of $${\text{H}}_{2}^{*}$$ and H2O*, and incandescent particles of coal (or tar) were detected, which is typical for all the studied coal marks. The spectrum-integrated brightness of the emission of coal particles during the exposure to a laser pulse increases almost linearly in the the metamorphism rank.

Datum: 01.04.2022

Ignition of High Energy Material Containing Ultradispersed Al/B Powder

### Abstract

This paper presents the characteristics of the oxidation of ultrafine aluminum powders of the Alex grade and a mechanical mixture containing Alex/B boron powder. The features of the ignition of high-energy materials containing ammonium perchlorate, butadiene rubber, and ultrafine metal powders, when heated by a radiant heat flux, are studied. It is established by thermal analysis that the rate of change in the mass of the sample and the total specific heat release during the oxidation of powdered aluminum diboride (Alex/B) in air significantly exceed the values of aluminum powder (Alex). Measurements on an experimental setup based on continuous CO2-laser and high-speed visualization of the stages of the response and development of flame processes show that the use of Alex/B in the composition of a high-energy material does not lead to a significant change in the time characteristics of ignition under the same heating conditions. At the same time, the intensity of the outflow of gaseous decomposition products with metal particles from the combustion surface of the fuel composition increases due to an increase in the heat flux in the zone of the gas-phase reactions and on the surface of the reactive fuel layer during the oxidation of aluminum and boron particles.

Datum: 01.04.2022

Conversion of Low Caloric Fuels to Synthesis Gas in the Filtration Combustion Mode in a Moving Layer of a Granulated Heat Carrier

### Abstract

The possibility of converting low-caloric fuels into synthesis gas by their partial oxidation in a moving porous layer of a granular heat carrier is theoretically studied. The process is considered in a new version of the reactor with a counterflow of a solid granular heat carrier and reacting gases. A feature of the reactor is the presence of an additional heat exchanger, where the oxidizer gas is preheated due to the residual heat of the solid heat carrier discharged from the reactor. Theoretically, in the approximation of the absence of heat loss and established thermodynamic equilibrium in the products, the macrokinetic modes of the process are considered depending on the main control parameters: the flow rate of the oxidizer gas, the flow rate of steam, the flow rate of the solid heat carrier, and the fuel composition. A quantitative calculation of the temperature and composition of the products in various combustion modes is carried out for the air-steam conversion of isopropanol and the air conversion of low-caloric pyrolysis gas. It is shown that the scheme under consideration provides a possibility to convert low-caloric gas at a temperature above 1500 K with a chemical efficiency of gasification over 90%.

Datum: 01.04.2022

The Thermochemical Properties of Naphthalene Derivatives

### Abstract

The objects of this study are nitro derivatives of naphthalene, of which only 1-nitronaphthalene has experimentally determined enthalpies of the formation in the gas phase by different researchers. Based on the double difference method, the enthalpies of the formation of naphthyl-1 and naphthyl-2 radicals are calculated and used to correct the enthalpies of the formation of 1- and 2-nitronaphthalene and other 1- and 2-naphthalene derivatives. The dissociation energy of bonds D(С–NO2) in 1- and 2-nitronaphthalene are calculated based on the obtained data. In nitrobenzene, the value of this bond coincides with that in 1- and 2-nitronaphthalene. A joint calculation of the C–H and C–C bond energies in naphthalene and benzene (from the enthalpies of atomization) shows that their values are the same. This makes it possible to estimate the rearrangement energy of naphthalene radicals as zero.

Datum: 01.04.2022

Effect of Annealing Samples of Thermally Reduced Graphite Oxide on Their Electrophysical Characteristics

### Abstract

A comprehensive study aimed at finding fillers for modern composite radio-absorbing materials is carried out. The results of measurements of the electrophysical characteristics of powders of thermally reduced graphite oxide (TRGO), including presaturated acetic acid, are given. The effect of annealing the studied powders in the temperature range from 473 to 1173 K on low-frequency and microwave conductivity, density at pressures up to 5 MPa, and the magnitude of the EPR signal is considered. The results of measurements presented of the complex permittivity of all powders at a frequency of 9.8 GHz are presented. It is found that with an increase in the annealing temperature of the powders, their low-frequency and microwave conductivity increases, while the electron paramagnetic resonance (EPR) signal decreases.

Datum: 01.04.2022

Category: Current Chemistry Research

Last update: 28.03.2018.