Russian Journal of Physical Chemistry A

The experimental results of measurements of concentrations of O₂(a¹Δ_g) and O₂(b¹Σ_g⁺) in a fast-flow gas system with no plasma-chemical processes involving electrons and ions are described using a numerical spatially two-dimensional model. The dependences of O₂(a¹Δ_g) and O₂(b¹Σ_g⁺) concentration profiles on the gas pressure, the fraction of O atoms in O/N₂ mixtures, and O₂ additions to the gas mixture are obtained. The need to take into account the detailed vibrational kinetics of ozone and the processes of its formation on the tube surface in the model is shown. The treatment of the reaction of three-body recombination of O atoms on M = N₂, O₂ taking into account the reverse dissociation reaction of the formed highly excited molecule is proposed, and the functional dependence of the resulting coefficient k_rec(T)—the rate of three-body recombination is obtained, which agrees well with the measured temperature dependences k_rec(T). The channels of further relaxation of the formed excited molecules and oxygen atoms are obtained.

The saturated vapor pressures of malic acid diesters and linear С₁-С₅ alcohols are determined using the transpiration method in the temperature range of 303–369 K. The enthalpies of vaporization of esters at 298.2 K are determined on the basis of the obtained data. Correlations of the enthalpies of vaporization from Kovats indices and number of carbon atoms are obtained. The contributions of the hydroxyl group and intermolecular hydrogen bonds to are estimated. The author’s QSPR method for calculating the values of the enthalpies of vaporization of esters of hydroxy acids is modified.

Corrosion of low-carbon steel in the flow of H₂SO₄ solutions containing Fe₂(SO₄)₃, including media with additives of corrosion inhibitors, viz. catamine AB (a mixture of quaternary ammonium salts) and IFKhAN-92 (3-substituted derivative of 1,2,3-triazole) is studied. In the discussed medium, partial reactions of anodic ionization of iron, cathodic reduction of H⁺ and Fe(III) cations are realized on steel. The first two reactions are characterized by kinetic control, and the latter is characterized by diffusion control. The accelerating effect of Fe₂(SO₄)₃ on the corrosion of steel in H₂SO₄ solution is mainly due to the reduction of Fe(III). In contrast, in an inhibited acid, the accelerating effect of Fe(III) cations affects all partial reactions of steel. The data on corrosion of low-carbon steel in the flow of the studied media obtained by mass loss of metal samples are in satisfactory agreement with the results of the study of partial electrode reactions. The accelerating effect of Fe₂(SO₄)₃ on steel corrosion in the flow of H₂SO₄ solutions, including in the presence of inhibitors, is noted. In these media, steel corrosion is determined by the convective factor, which is characteristic of diffusion-controlled processes. Unlike catamine AB, the IFKhAN-92 inhibitor ensures a significant slowdown of steel corrosion in the flow of H₂SO₄ solution containing Fe₂(SO₄)₃. The reason of higher inhibitor effects of IFKhAN-92 at protection of steel in the considered media as compared to catamine AB is that it slows down partial electrode reactions of metal more substantially.

A new method for processing the results of the temperature-programmed desorption (TPD) of ammonia from heterogeneous catalyst surfaces and an approach for automatic deconvolution of TPD kinetic curves are proposed. This method uses the Polanyi-Wigner kinetic model with formal kinetics approaches for simple reactions, which imposes restrictions on the observed orders of 1, 2, or 3. The parameters of TPD curves are selected based on the inverse simulation using the Runge-Kutta method and fitting them to experimental points using dynamic model parameters changes. As an example, several heterogeneous catalysts are presented in this work. TPD-NH₃ of titanium silicalite-1 and silicalite-1 is obtained using one third-order desorption kinetic equation. TPD-NH₃ of the three samples of γ-alumina is obtained using two desorption peaks with similar kinetic parameters.

Complexes of cobalt tetra-4-carboxy-phthalocyanine are prepared. The heat effects of dissolution of crystalline cobalt tetra-4-carboxymetallo-phthalocyanine in aqueous solutions of KOH of different concentrations (from 0.002 to 0.02 mol/L) at 298.15 K are determined by the direct calorimetric method. The values of standard enthalpies of compound formation are calculated by the additive group method based on group systematics with Benson-type fragment classification, which takes into account the influence of the primary environment of atoms. The standard enthalpies of formation of dissociation products of complexes of tetra-4-carboxy-phthalocyanines with cobalt in the aqueous solution are calculated.

The sample of metal-organic UiO-66 framework (Zr₆O₄(OH)₄bdc, bdc = benzene-1,4-dicarboxylate/terephthalate), which is a promising adsorbent of persistent organic pollutants from aqueous medium, is obtained by the original method in the medium of unconventional “green” solvent, triethylene glycol (TEG), under conditions of microwave activation of reaction mass at atmospheric pressure according to one-step approach. PET-UiO-66 material is synthesized using polymer waste, viz. recycled polyethylene terephthalate (PET), as a source of organic linker (terephthalic or benzene-1,4-dicarboxylic acid, H2bdc) for framework formation. Its adsorption activity is first studied in the adsorption removal of tartrazine food dye (E-102) from aqueous solutions. It is found that the kinetics of the adsorption process obeys the pseudo-second-order model, and its thermodynamics corresponds to the Langmuir model.

In this work, we have demonstrated for the first time the possibility of electrochemical formation of Ge-Co nanostructures on a copper substrate, which are globules whose size reaches 1 μm, consisting of smaller particles whose size does not exceed 10 nm. Such nanostructures demonstrate a sufficiently high reversible capacity of about 850 mAh/g and good stability under long-term cycling.

Potentials of the embedded atom model (EAM) for liquid silicon and germanium are proposed. The potentials are calculated from diffraction data using the Schommers algorithm and presented in the form of tables and piecewise continuous polynomials. Each pairwise contribution to the potential has a form close to a hard-sphere one with a step down. The properties of liquid Si and Ge at temperatures up to 2000 K are calculated, viz. the density, energy, bulk modulus, and self-diffusion coefficients. The agreement with the experiment is noted to be good. The bond direction is found to almost completely disappear after melting for ordinary densities of liquid Si and Ge. The bond direction is assumed to be able to appear at heating and when the density of melts is decreased by 2–3 times.

The colloidal-chemical properties of soluble and poorly water-soluble block copolymers of ethylene oxide and propylene oxide (pluronics), as well as the rheological properties of interfacial adsorption layers (IAL) formed by them and the polymer formed at the initiation of polymerization on the particle surface are studied. The influence of temperature, surfactant and polymer concentration on the values of the effective elastic modulus determined at lateral deformation of IAL is evaluated. The strongest interfacial layers are shown to be formed by low water-soluble pluronic containing a hydrophilic polyoxyethylene block surrounded by two hydrophobic polyoxypropylene blocks. The high strength of the interfacial adsorption layer on the particle surface is found to allow obtaining polymer suspensions with high polymer content (up to 33%) and narrow particle size distribution.

When predicting retention indices using deep learning, there is usually no way to assess the reliability of the prediction for a particular molecule. In this work, using stationary phases based on polyethylene glycol and the NIST 17 database as an example, it is shown that, on average, the closer the molecule in the training data set is to the compound being predicted, the more accurate the prediction. Tanimoto similarity of “molecular fingerprints” ECFP is the most appropriate molecular similarity calculation algorithm for this problem among the four considered. It is shown that for a number of transformation products of unsymmetrical dimethylhydrazine, whose structure was established using this prediction, it could be very unreliable.

The behavior of a smooth gold electrode in the medium of bridged 1,2,4-trioxalane in acetonitrile is studied by cyclic voltammetry and gravimetry methods. It is found that during the cathodic process, the reduction of the peroxide bond in the bridged 1,2,4-trioxalane molecule takes place at the electrode surface followed by the formation of a diketone moiety. During anodic oxidation, the formation of colloidal gold particles is detected.