Home – Home – Jornals – Chemistry for Sustainable Development 2024 number 3

The principles of creating a water-organic disinfectant emulsion (WODE) are described. The emulsion can be applied to various types of surfaces and form a film with a prolonged bacteriostatic/bactericidal effect. When applied to the surface under treatment in a dropwise manner, the composition based on polyacrylamide and special additives will form a durable film, which, in turn, will promote the provision for high sanitary and anti-epidemic measures. The film formed on the surface can be removed by wetting with water and subsequent wiping, which will not lead to the disruption of the general disinfection regime. The water-organic disinfectant emulsion is a composition based on polyacrylamide, a surfactant, polyalcohol (glycerol) and zinc/copper sulphate. The factors responsible for the uniformity of WODE film formation were studied. The criteria for improving rheological and technological properties (wettability, spreadability, moisture absorption) under environmental conditions have been determined. It has been established that higher spreadability and improved strength properties of water-soluble polymer films are achieved by adding surfactants (especially nonionic ones) and a polyalcohol to the composition. By modelling the abrasion process, the mechanical parameters of water-soluble polymer biocidal films were studied. The disinfectant effect of the developed aqueous-organic film-forming composition was studied with respect to the strains of microorganisms: Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. It is proven that the provision of bacteriostatic and bactericidal properties is explained not only by the introduction of copper sulphate or zinc sulphate into the biocide composition, but also by the inhibitory properties of polyacrylamides of various brands themselves. It has been established that polyacrylamide, despite the presence of carbon and nitrogen in its composition, is not an accessible source of nutrition for the cells of pathogenic microorganisms.

The results of studied on the use of ultrasound in catalyst synthesis and processing are summarised. It is demonstrated that exposure to ultrasound can regulate the textural and structural characteristics of catalysts by varying exposure time and the amplitude of ultrasonic radiation. Optimisation of the conditions of ultrasonic treatment of the catalysts is determined to provide improvement of their physicochemical properties. This allows achieving higher reagents conversion and selectivity of the formation of target products in various chemical reactions. Examples of ultrasound application from the viewpoint of following the green chemistry principles are considered. It is shown that ultrasound application in organic synthesis promotes improvement of chemical process characteristics and reduces reaction time.

The safety of administering aerosolised cephalosporin antibiotics is evaluated, relying on the results of histological examination of lungs after inhalation for different time intervals. Long-term inhalation is detected to cause no toxic effect on the lungs.

Tin oxide is a wide-gap semiconductor material that is widely used in photooxidation reactions of organic compounds. However, the relationship between energetic and photoelectrocatalytic properties in the oxidation of small organic molecules has not yet been sufficiently explored. In this work, a series of tin oxides were synthesized using hydrothermal, sol-gel, and template methods. Polystyrene spheres with a size of 250 nm, as well as cetyltrimethylammonium bromide, were used as templates. X-Ray diffraction, low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy and diffuse reflectance spectroscopy methods were used to study the structure, surface composition, optical and energy characteristics. Using photoelectrochemical methods, the potentials of the conduction band and valence band were determined, and photocurrents in aqueous and aqueous-methanol solutions were studied depending on electrode polarization. It is shown that the preparation method (sol-gel or hydrothermal) does not affect the position of energy bands, while the use of a template during synthesis leads to an increase in the average pore diameter in the samples and an increase in photocurrent values in the presence of methanol. It has been established that for template-synthesized samples, the magnitude of photocurrents in a water-methanol mixture increases with an increase in the valence-band potential. The sample prepared by the hydrothermal method using a template showed the highest photocurrent values both in the background electrolyte (17.3 μA/cm²) and in the presence of methanol (26 μA/cm²), compared to the sample prepared without using a template in the electrolyte with the addition of methanol (7.6 μA/cm²) and without it (7.8 μA/cm²).

A comprehensive study of the hydrocarbon composition and physicochemical properties of by-products of oil refining and petrochemistry was carried out to search for new low-margin components of low-viscosity marine fuel (LMF) and to optimize the fuel composition for expanding the raw material base of LMF. The possibility of involving the heavy fractions from primary and secondary oil refining in LMF has been established: 10-12 % higher-weight diesel fraction, 47-60 % straight-run medium distillate fraction, 2-10 % heavy diesel fraction, 35% vacuum distillate, 10 % still residue from hydrogenation units, 4-10 % light catalytic cracking gas oil. A method has been found for obtaining a new component of LMF - a fraction boiling within 180-270 °C, obtained from oil refining wastes after their dehydration and fractionation in the yield of up to 30 %, the involvement of which in LMF (5 %) will give an economic effect of about 7 million roubles per year. Mathematical modelling was used to optimize the composition of fuel from the main and by-products, taking into account the production volumes and the actual values of critical indicators of each component. A method has been found for obtaining a new component of LMF - a fraction boiling within 180-270 °C, obtained from oil refining wastes after their dehydration and fractionation in the yield of up to 30 %, the involvement of which in LMF (5 %) will give an economic effect of about 7 million roubles per year. Mathematical modelling was used to optimize the composition of fuel from the main and by-products, taking into account the production volumes and the actual values of critical indicators of each component.

The effect of heavy oil treatment with isopropyl alcohol (IPA) for 8 h at a temperature of 25-100 ^oC on the composition and structure of resins is investigated. The objects of investigation were heavy oil from the Zyuzeevskoye field (the Republic of Tatarstan) and resins isolated from this oil. It is established that the resin content increases by almost 3 wt% as a result of heavy oil treatment with IPA at 100 °C. It is shown than an increase in the temperature of oil - IPA (20 wt%) mixture treatment from 25 to 100 °C causes an increase in sulphur and oxygen content in resins by 0.5 and 0.8 wt%, respectively, and a decrease in the Н/С atomic ratio from 1.40 to 1.38. The aromaticity factor of resins increases by 0.17 %, while the fraction of aliphatic carbon decreases. It is concluded that oil treatment with isopropyl alcohol, aimed at a decrease in the content of resinous and asphaltenic substances, is unreasonable because it causes unfavourable formation of the additional amount of resins.

The annual dynamics of (1) chloroform-extractable substances (CES) and petroleum hydrocarbons (PH) in riverside fluvial sediments, in the bottom sediments of the mixing zone of river and sea waters, and in the bottom sediments of the marine area, and (2) the abundance of hydrocarbon-oxidizing (HOB) and heterotrophic (HB) bacterial groups in the bottom sediments of the marine area and riverside sediments is analysed. The maximal content of CES was found in the marine area (450±17.5 mg/100 g), and the minimal one - in the river part (127.6±10.9 mg/100 g), in the mixing zone of river and sea waters - 370±37.9 mg/100 g. The average concentrations of PH are distributed similarly to the concentrations of CES: the maximal values (127.5±10.9 mg/100 g) are detected in marine ground, the values for the sediments of the mixing zone are slightly lower (103.1±9.4 mg/100 g), and the minimal values (54.8±23.9 mg/100 g) are detected in river sediments. The physicochemical characteristics of bottom and coastal sediments are presented. The abundance of HB in the bottom sediments of the marine area varied from 7.5∙10³ to 2.5∙10⁶ cells/g, respectively, and from 9.5∙10³ to 9.5∙10⁸ cells/g in the river area. There was no seasonal variability in the abundance of HB at both areas. Hydrocarbon-oxidizing bacteria were registered in 100 % of the samples of bottom and riverside sediments of the designated water areas. The abundance of HOB varied from 25 to 2.5∙10⁴ cells/g in the marine zone and from 25 to 4.5∙10³ cells/g in the river zone. The maximal values of HOB abundance in the riverside sediments were recorded during the flood period (February-April).

The acidity of NH-groups of a number of sulphonamides and glycine derivatives in a dimethyl sulphoxide medium has been investigated using the potentiometric method. Dissociation constants of these compounds are determined from titration curves. It is shown that the acidity of NH groups in the studied sulphonamides is controlled by the polar effect of substituents. The possibility of quantitative potentiometric analysis of glycine derivatives has been established for the first time. Biological activity has been predicted with the help of PASS software. The correlation of NH group acidity with the biological potential of the compounds has been established.

The solution to the problems of ecological safety when cleaning water objects from organic pollutants is indissolubly related to developing new sorbents and improving the technologies of their synthesis. Various materials in dispersed and granulated forms are successfully used in the production of sorbents. This article deals with the development and improvement of the technologies for producing the sorbents of petroleum and petroleum products. As a basis for the development of new sorbents, the properties of the granular foamed silicate obtained from the siftings of waste products from mining and processing plants were studied. The trial batches of oleophilic sorbents were obtained through thermochemical modification of hydrocarbons in the gas-vapour phase. It has been established that foamed silicate does not change its porous structure and amorphous state after thermo-chemical modification, retaining the high sorption activity. The nature of the porous structure of sorbents and the influence of porosity on their key properties, such as oil capacity, water absorption, and buoyancy, are investigated. The studies of the fractions of modified foamed silicate revealed low water-absorption capacity of the coarse- and middle-sized fractions. The minimum water absorption was determined for the fine fraction of the modified material, which is related to the absence of pores in these samples. Determination of oil capacity characteristics provides evidence of high oil receptivity and sorption capacity of the modified foamed silicate with respect to petroleum products. The results of experiments on sorbent regeneration after the end of its service life are presented. The developed semi-production experimental plant for the modification and regeneration of porous loose materials in the fixed bed is presented. The technological scheme of regeneration is proposed, allowing for regeneration and repeated modification of the used sorbent during one processing stage without any decrease in its sorption properties. The advantage of the developed technology of sorbent properties recovery is in the implementation simplicity and economic rationality. The repeatedly modified sorbent retains its characteristics and, first of all, sorption properties with respect to petroleum products. The practicability of developing new sorbents of petroleum products based on granular foamed silicate is demonstrated.

A fuel processor for autothermal reforming of diesel fuel into synthesis gas is developed and tested. The developed reactor is demonstrated to possess a fast start-up and high efficiency. During the tests, complete conversion of diesel fuel and the composition of reaction products close to equilibrium values were achieved. The thermal circuit of a power plant based on a solid oxide fuel cell (SOFC) with the electrical power of 1 kW was optimized. The results obtained are the basis for the further development of a real prototype of a power plant based on planar SOFC with an integrated diesel fuel processor, opening up the prospects in the area of making low-power electrochemical generators.

The binary systems of deep eutectic solvents (DESs) have been synthesised and investigated: tetraxydroxy alcohol - a salt of a quaternary ammonium base (DES₁), tetrahydroxy alcohol - carbamide (DES₂), a salt of a quaternary ammonium base - carbamide (DES₃), and the ternary system tetrahydroxy alcohol - a salt of a quaternary ammonium base - carbamide (DES₄). Eutectic compositions of binary systems DES₁, DES₂ and DES₃ are characterised by significantly lower pour/melting points than those of the initial components. The lowest pour point among the binary mixtures is that of eutectic composition DES₃. The ternary system is characterised by an even lower pour point (-14 °C), which is associated with the formation of intermolecular donor-acceptor hydrogen bonds within the system. An aqueous solution of DES₄ with the concentration of 26 wt% was prepared, and its pH value was determined depending on temperature during preparation. At room temperature, pH of three-component DES is 6.6-7.1, but after thermostating for 6 h at 150 °C pH increases to 9.2 due to carbamide hydrolysis. It is assumed that further on, using DES₄ as the basis for an alkaline oil-displacing composition directly in the reservoir, under the influence of the temperature of injected heat carrier, CO₂ is formed, along with the ammonia buffer system with the maximal buffer capacity within the pH range 9-10. Resulting carbon dioxide, dissolving predominantly in oil, will cause a decrease in its viscosity, on the one hand, while the formed alkaline medium, being most favourable for surfactant performance due to a decrease in interfacial tension, liquefaction of high-viscosity layers or films at the oil-water-rock boundaries, on the other hand, will ensure efficient use of this system for oil displacement. In addition, the oil-displacing composition based on DES₄ will be low-solidifying, which opens the possibility of its transportation and use in the northern regions and the Arctic zone.

Samples of primary low-sulphide gold-quartz ore and oxidised host rock containing up to 10 wt% sulphides and 5 wt% their oxidation products were investigated to reveal the relationship between the migration of elements during the hypergenic transformation of ores and rocks and their mineral composition. Mineralogical studies employed optical and electron microscopy to identify the shapes and sizes of mineral individuals and aggregates and to determine their chemical composition. It is determined for major element content that the oxidised host rocks contain significantly more iron, sulphur, aluminium, potassium and phosphorus than primary low-sulphide quartz gold ores, while silicon and calcium content is lower. This is due to the removal of sulphur and iron into the near-vein rocks with the formation of primarily pyrite and arsenopyrite, and the presence of aluminosilicates (feldspars and layered silicates) in them. The same applies to arsenic and antimony, as their concentrations are higher in the host rocks than in the ores. The rates of lithophile elements recovery from primary gold-quartz ores are much higher than those from oxidised host rocks. Сhalcophile elements, on the contrary, are more intensively transferred to the solution from host rocks. Thus, the complex of elements extracted from ore suspensions is directly determined by their mineral composition. The main carrier of gold is native gold and its tellurides. Silver is associated with low-grade gold, copper and silver sulphosalts, and also tellurides.

The milestones of the development of X-ray diffraction and crystal chemical studies in the Laboratory of Crystal Chemistry of the Nikolaev Institute of Inorganic Chemistry SB RAS for 1958-2024 are highlighted.

The targeted screening of 11 phenolic toxicants (phenol, chlorophenols, 2,4-dichlorophenoxyacetic acid, octylphenol, nonylphenol, bisphenol A) has been carried out over river water and bottom sediments (BS) in the middle reaches of the Don river within the boundaries of the Voronezh Region. Three sampling points were selected for quantitative chemical analysis: in the zone affected by the discharge of sewage treatment plants of a large city (Voronezh), in the district centre (the city of Liski), and in an area with insignificant anthropogenic influence. The concentrations of phenolic compounds were determined using gas chromatography - mass spectrometry (GC-MS), the analytes were preconcentrated on a magnetic sorbent functionalised with aminated hypercrosslinked polystyrene. Sampling was carried out four times a year, taking into account seasonal climatic fluctuations and precipitation. The maximum concentrations were established in the spring for 2,4-dichlorophenoxyacetic acid (1022 ng/L) and 2,4-dichlorophenol (557 ng/L). In bottom sediments, the highest concentrations are achieved for alkylphenols: 1.99 and 7.84 μg/g for octylphenol and nonylphenol, respectively. Bisphenol A has not been found in detectable amounts in waters, however, a significant concentration of this compound has been found in bottom sediments: 3.18 μg/kg. The bottom sediments were also determined to contain 2,4,5-trichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol. The maximum concentrations of phenolic pollutants in river water are usually observed in spring during high water and after heavy rainfall. Phenol concentrations in bottom sediments are less susceptible to seasonal fluctuations. The hydrophobicity of substances and an increase in their stability against degradation significantly affect their accumulation in BS.

In order to develop a catalytic technology for processing coal mine methane into hydrogen-containing gas, thermodynamic analysis of methane tri-reforming (TRM) was carried out, and the influence of temperature (600-850 °C), contact time (0.04-0.15 s), linear feed rate (80-240 cm/min) and composition (CH₄ / CO₂ / H₂O / O₂ / He = 1: (0.3-0.5) : (0.2-0.5) : (0.1-0.3) : (2.9-3.2)) of the reaction mixture on the conversion of the initial reagents and target products in the TRM process in the presence of a supported Ni catalyst was studied. It has been shown that with an increase in the temperature of the TRM reaction from 600 to 800 °C the process performance improves (methane conversion: 36 → 94 %, carbon dioxide conversion: 57 → 97 %, hydrogen yield: 37→ 91 %, carbon monoxide yield: 44→ 94 %, molar ratio H₂/CO: 1.5 → 1.7), and at a reaction temperature of 850 °C the process indicators are close to equilibrium values. It has been established that varying the O/C value and the composition of oxidants makes it possible to regulate the performance of TRM process. The optimal conditions for the TRM process were identified to achieve maximum efficiency of the catalytic processing of coal mine methane into hydrogen-containing gas: temperature - in the range of 800-850 °C, contact time - 0.15 s, linear feed rate - 160 cm/min and molar ratio of reagents in the initial feed - CH₄ / CO₂ / H₂O / O₂ = 1: 0.5 : 0.2 : 0.25.

A mathematical model of the flow of hydrogen from gas mixtures through the walls of capillary tubes made of metallic nickel has been developed, taking into account the inhomogeneity of the partial pressure of hydrogen along a long tube, as well as temperature nonuniformity in different regions of the tube. Using the model and relying on experimental data, the kinetic parameters of hydrogen transport were calculated within the temperature range of 600-850 ºС and the hydrogen partial pressure range of 0.3-0.8 atm. The model can be used in the design of membrane modules for hydrogen separation from gas mixtures to calculate the length of individual membranes, their number, and the optimal flow rate of the hydrogen-containing gas mixture through the membrane.