Vol 97, No 4 (2023)

Current approaches to creating mixed inhibitors of metal corrosion in acid solutions and possible pathways of their action on the corrosion process are reviewed. Quantitative approaches to assessing the mutual effect of the components of mixed inhibitors are analyzed, and criteria for the synergism of their action are discussed. The high efficiency of ternary mixed inhibitors based on triazole derivatives in the protection of different steels in high-temperature acid solutions (t = 100–180°C) and solutions of acid mixtures containing Fe(III) salts is shown. Important practical advantages and disadvantages of the different groups of inhibitors of metal corrosion in acidic media are discussed. Data on protecting metals in acidic media with so-called green inhibitors are summarized, and the prospects and discrepancies associated with their practical application are discussed. The need to search for technologies allowing the use of inhibited acid solutions that meet the environmental requirements of current production while simultaneously allowing for the hazard of solutions of the acids is shown.

The heat capacity of sodium-alloyed lead babbitt BNa (PbSb15Sn10Na) is determined experimentally, and the temperature dependences of the changes in the thermodynamic functions of this alloy are calculated. The temperature dependence of the heat capacity of babbitt BNa is studied in the cooling mode using the SigmaPlot 10.0 software. Polynomials are determined for the temperature dependences of the heat capacity and the changes in the thermodynamic functions (enthalpy, entropy, and Gibbs free energy) of babbitt BNa and a reference sample (S00-grade Pb), that describe these dependences with coefficient of correlation Rcorr = 0.999. It is shown that the heat capacity of babbitt BNa grows along with the content of sodium, its enthalpy and entropy grow along with temperature and the content of sodium, and its Gibbs energy falls.

A study is performed of the effect process temperature and pressure have on the distribution of CO2 and H2S gas hydrate in a model methane-containing gas mixture of CH4 (89.00 mol %)–CO2 (5.00 mol %)–n-C4H10 (3.00 mol %)–N2 (2.00 mol %)–H2S (1.00 mol %) containing components of natural gas. Modeling is done at low (4.00 MPa) and high (8.00 MPa) pressures in the 272.15–278.15 K range of temperatures. The temperature dependences of the coefficients of the gas hydrate distribution of natural gas components are shown to differ. The maximum coefficients of the gas hydrate distribution of CO2 and H2S are 1.24 and 31.83, respectively, at a process temperature of 272.15 K and a pressure of 8.00 MPa. It is found that n-C4H10 in natural gas lowers the coefficient of the gas hydrate distribution of CO2. It is concluded that natural gas deposits with low contents of n-C4H10 must be used to effectively concentrate CO2 in the gas hydrate phase.

A study is performed of the catalytic properties of Cu–Zn catalysts on Al2O3 and SiO2 supports (Acros) in the reaction of CO2 hydrogenation to obtain methanol. A sample of 30Cu15Zn/Al2O3 displays great selectivity toward methanol. A sample of 30Cu15Zn/SiO2 has the highest methanol performance. The methanol performance of a sample of 10Cu5Zn/Al2O3 is doubled when the pressure is raised from 10 to 30 atm, and a 94% increase in selectivity is observed. A sample of catalyst 10Cu5Zn/SiO2 does not lose its activity after 10 h of a catalytic reaction, and its methanol performance grows with repeated use

Experimental data are presented on the surface tension and density of acetone (chemically pure) and ethanol (pure for analysis) and acetone–ethanol solutions of different concentrations. The temperature dependence of density is measured with a VIP-2MR vibration density meter with a systemic error of ±0.01 g/cm3. Surface tension (ST) is measured with hanging drops on a DSA-100 KRUSS tensiometer whose systemic error is no more than 1%. Experimental measurements show the concentration dependences of molar volumes and surface tension within the experimental error are described by a linear function. Calculations of the ST isotherms according to the equation of A.A. Zhukhovitsky, obtained by assuming the surface layer and bulk phase are ideal, show the theoretical ST isotherms coincide with experimental ones within the experimental error. Calculations of the thermodynamic parameters of the surface layer show the coefficients of thermodynamic activities of the components in the surface layer are close to unity throughout the range of concentrations. Based on these results and the finite thickness of layers, it is concluded that the surface layers of ethanol–acetone solutions is ideal.

The acid–base properties of β-alanine (β-Ala) in aqueous solution were studied by the pH-metric method in the temperature range 278.2–318.2 K and at I = 0.1 M KCl. The ionization constants (pKi) of β‑Ala at different temperatures were calculated. The ionization constants were found to change depending on the temperature: an increase in the temperature leads to a decrease in pKi for both carboxyl and amine groups, which indicates that the degree of ionization of β-alanine increased and its acidic properties were enhanced. The thermodynamic characteristics (ΔН0, ΔS0, and ΔG) of the corresponding ionization processes were determined by the temperature coefficient method.

Molecular spectroscopy in the UV and IR ranges is used to perform a comparative study of the decomposition of toluene and heptane during mechanical activation with titanium. It is shown that high-energy mechanical processing is effective for obtaining low-molecular-weight alkanes, the amounts of which are largely determined by the nature of the hydrocarbons. The effect the mill carrier’s speed of rotation has on the depth of hydrocarbon decomposition and the composition of products of the mechanical processing of the liquid phase is considered. It is shown that at a speed of 600 rpm, heptane begins to decompose at short periods of mechanical activation (MA), while toluene is stable up to 30 h MA. Considerable structural and chemical transformations occur in toluene after only 20–30 h of mechanical treatment at a speed of 890 rpm.

A low-temperature approach is described for preparing mesoporous metal–organic frameworks using nontoxic solvents and pre-synthesized polynuclear iron complexes as secondary building units. The obtained compounds are characterized via IR and Mössbauer spectroscopy, X-ray powder diffraction analysis, thermogravimetric analysis, and differential scanning calorimetry. The specific surface of the obtained compounds and their adsorption capacity for organic dyes methylene blue and Congo red are determined. Particular attention is given to dependences M(T) and M(H) of the magnetic moment of the obtained samples on temperature and strength of the magnetic field, respectively. The dyes’ adsorption characteristics and efficiency of sorption are determined by varying such factors as period of contact, amount of adsorbent, and temperature. The removal of dye at a concentration above 90% is observed as early as 20–30 min after the beginning of adsorption. Langmuir and Freundlich isotherms are used to describe the experimental data. It is shown that the process of adsorption at the initial concentration of the dye is described most accurately by the Langmuir adsorption isotherm. The rate constants of adsorption are calculated using pseudo-second order kinetic equations.

Here we introduce a methodology for calculating vertical detachment energies (VDE) and vertical ionization energies (VIE) of anionic and neutral chromophores in aqueous environment. The proposed method is based on the extended multiconfigurational quasidegenerate perturbation theory coupled to the explicit treatment of solvent effects in the frame of the effective fragment potential method. We show that the solvent polarization contribution must be considered for getting accurate quantitative estimations of VDEs and VIEs. The calculated values of VDE for phenolate (7.3 eV) and VIE for phenol (7.9 eV) in aqueous environment are in good agreement with the experimental results obtained using X-ray and multiphoton UV photoelectron spectroscopy. Our approach will be useful for studying processes of photoinduced electron transfer from anionic as well as neutral biological chromophores in aqueous solution.

Laboratory studies and field tests identify the presence of a pyrophoric compound (iron disulfide) in the corrosion products of the internal surfaces of the walls as the main cause of spontaneous combustion of the tanks with sulfurous oil. When nitrogen is introduced into the vapor-gas phase, the formation of pyrophore in the tank stops and the probability of spontaneous combustion significantly reduce. This strongly reduces the corrosion rate as well.

Growing concerns about the environment are prompting the search for alternative energy sources and the possibility of processing agricultural waste into highly efficient absorbents. That is why the article considers methods for obtaining high-energy fuel from pinewood using acidic additives and the possibility of using chemically treated cherry stone shells as a carbon sorbent is evaluated. With the use of low-temperature pyrolysis, a number of carbon-containing materials have been obtained. The carbon content in these materials depends on the reagent used to treat the feedstock, the temperature and time of pyrolysis. The subsequent activation of carbonizate from the cherry stone shell with oxidizing agents revealed that nitric acid significantly increases the cation-exchange capacity of the material, which allows it to be used as an adsorbent.