Home – Home – Jornals – Chemistry for Sustainable Development 2025 number 3

The effect of mineral components of brown coal on the efficiency of coal microparticle combustion under pulsed periodic exposure to laser radiation (1064 nm, 120 s, 3 Hz) has been studied. The experimental samples were pressed tablets with a density of 1 g/cm³. Under microparticle irradiation with the same doses, the burnt mass is larger in samples with higher ash content, which indicates the catalytic effect of the mineral part of coal on burnout rate. The morphology of the surface and transverse chips of the samples after irradiation was studied by scanning electron microscopy. It has been found that the fused drops of minerals are observed on the surface of high-ash samples, and the channels of burnt organic part are observed on the transverse chips, along with the formation of calcium oxide phase.

Results of the comparative gas chromatographic - mass spectrometric analysis of the structural-group and molecular compositions of nitrogen-containing basic compounds, isolated by acid extraction from the deasphaltisates of high-sulphur natural asphaltite and the liquid products of its conversion in supercritical water (SCW) at 400 °C and 40 MPa in the presence of potassium hydroxide are presented for the first time. The higher yield of the acid extract in conversion products in comparison with initial asphaltite suggests that an additional portion of low-molecular nitrogen bases is generated during the destruction of asphaltenes and resins of asphaltite under the process conditions. In both extracts, the compounds of homologous series of quinoline, thiophenoquinolines, benzoquinolines, benzothiophenoquinolines, benzoacridines, azapyrenes were identified. It has been determined for the liquid products of SCW conversion that the content of benzoquinolines and benzoacrydines with respect to quinolines increases by a factor of 1.5, and thiophenoquinolines - by a factor of 1.2. Furthermore, among most of the nitrogen base types, the fraction of unsubstituted compounds and/or compounds containing a smaller total number of carbon atoms in the aromatic ring substituents is observed to increase in the conversion products. A change in the content of nitrogen bases or their appearance in conversion products suggests the presence of such nitrogen- and nitrogen-sulphur-containing structural fragments in the molecules of resin-asphaltene substances (RAS) of natural asphaltite.

New efficient broad-spectrum preparations have been developed on the basis of the aqueous solution of Novochizol with the addition of Siberian pine bark extract (SPE) and usnic acid (UA), the substance isolated from the Usnea lichen genus. Optimisation of the procedures for fungicide extraction from plant raw materials has been carried out to reduce costs and obtain pure extracts in quantities sufficient to make complex preparations. During field experiments conducted in 2022-2023 in the Novosibirsk Region, we studied the effect of seed treatment with Novochizol forms with the addition of SPE and UA on the development of root rot and leaf diseases, growth processes and yield of spring wheat Novosibirskaya 31. The use of Novochizol + UA complex as the growth regulator contributed to the reduction of root rot in the phases of tillering and milky-wax ripeness by 53.3 and 41.6 %, and Novochizol + SPE complex by 25.0 and 37.0 %, respectively. When using the seed protectant Dividend Extreme, the corresponding indicators were 70.0 and 28.6 %, respectively. The above-mentioned Novochizol + UA, Novokhizol + SPE complexes and the Dividend Extreme preparation showed effectiveness against septoria, which was 65.0, 66.7 and 67.7 %, respectively. Seed treatment had a positive growth-stimulating effect on such parameters as sprout formation, tillering, biomass accumulation, plant density, height and area of the flag leaf, and significantly improved ear structure indicators. The effect of the form of Novochizol with the addition of UA was more pronounced. Seed treatment provided an additional yield relative to the control (2.7 t/ha) at the level of 0.3 t/ha when using Novochizol + UA and 0.2 t/ha when using Novochizol + SPE or the fungicide Dividend Extreme.

Computer models of tetra-n-alkylammonium tetrafluoroborates have been developed. The transport, structural, and thermodynamic properties were studied over a wide temperature range. It is shown that under the conditions of a model experiment, crystallisation processes in the organic salts under consideration are kinetically inhibited, and the models remain in a glassy state in the temperature range from the melting point to 300 K. The diffusion coefficients in the molten state are in accordance with the experimental results, and are within 10^-7-10^-8 m²/s.

The scheme of phase formation in Fe-Pt nanoalloy was established using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), including in situ heating, small-angle X-ray scattering (SAXS), and optical emission spectrometry with inductively coupled plasma (ICP-OES). The nanoalloy particles were synthesised using the co-reduction of precursor solutions (Fe²⁺ and [PtCl₆]^2-) with an alkaline solution of hydrazine hydrate. To determine the scheme of solid Fe-Pt phase formation, the reduction process was stopped after 10 and 300 s by diluting the reaction mixture with cold (2 °C) water. Comparison of the results obtained using XRD, XPS, SAXS, and ICP-OES methods allowed us to establish that the formation of the solid phase under reduction-oxidation reaction conditions is a staged process. The first and fastest stage is the formation of the Pt-phase with particle sizes ≈3 nm. The second stage involves the joint reduction of platinum and iron precursors on the surface of Pt particles formed at the first stage. The last stage is the formation of ultrafine particles enriched in Fe under the conditions of Pt precursor deficiency.

Physicochemical characteristics of thermolysis oil obtained from polypropylene have been determined. The hydrocarbon composition, studied by two-dimensional gas chromatography and high performance liquid chromatography, as well as calculation of the iodine value, shows that the major components of the resulting oil are isoalkanes and alkenes. The results obtained allow us to draw conclusions about the mechanism of polypropylene transformation during thermolysis, and data on the fractional composition, density and viscosity further characterise thermolysis oil from the perspective of a petroleum product.

Bioremediation is the most relevant and popular method of soil purification from oil pollution, especially in the northern regions. The results of field experiments to study the influence of the age of oil pollution on the efficiency of microbiological remediation of soils on the territory of the former oil pipeline (southwest of Yakutia) are presented. Purification was carried out by introducing the biological preparation based on enrichment cultures of indigenous hydrocarbon-oxidising microorganisms, previously isolated from the soils of this territory. It was found that the degree of destruction of fresh pollution a year after bioremediation was 77.4 %, and for old 7-year-old pollution it was only 34.3 % (of the level that remained 7 years after the oil spill). For the first time, a decrease in the efficiency of bioremediation processes has been considered from the standpoint of the chain free radical mechanism of microbiological oxidation. In the absence of a readily oxidised substrate, specifically alkanes from n-C₁₂ to n-C₂₄, as well as 12,13-methylalkanes, which naturally degraded over 7 years, the initiation of oxidation slows down, and the addition of the biological preparation no longer allows achieving high purification efficiency. In addition, the formation of intermediate reaction products (high-molecular naphthenic-aromatic hydrocarbons) could inhibit the chain oxidation process due to the formation of stable intermediate radicals. The new formation of resins during bioremediation leads to hydrophobisation of soils and disruption of their water-air regime, which also could have a negative effect on the oxidative biodegradation of oil pollution. It has been shown that the method of bioremediation of oil-contaminated soils is most effective in the case of fresh oil spills.

To specify the region-associated mineral composition of the raw nut oil and seeds of the dwarf cedar pine (Pinus pumila) growing in an environmentally clean area of the Magadan Region, the content of 25 macro- and microelements in the raw materials was analysed. The results of the study allow us to conclude that the raw cedar nut oil is a source of the important trace elements - Zn and Cr. It has been determined that pine nuts can be considered as valuable food item because the inclusion of nuts in the diet in the amount of only 100 g can half satisfy the adult daily needs for Mg, P, Cu, Se, and Zn. This allows us to recommend raw cedar nut oil and pine seeds to be included into daily diet as a biologically active additive, which will replenish the deficiency of some vitally essential macro- and microelements for persons of any age when taken regularly in the amount not more than 1-2 teaspoons a day. No excess of the permissible levels of toxic elements in the studied samples was found, which confirms the environmental safety of the areas where the wild nut bush grows.

The In₂O₃-ZrO₂ and In₂O₃-CeO₂ catalysts for the hydrogenation of CO₂ into methanol were prepared and studied. The effect of oxide support on the physicochemical and catalytic properties of catalysts (CO₂ conversion, selectivity and productivity with respect to methanol) was studied using transmission electron microscopy, X-ray diffraction, temperature-programmed reduction by hydrogen, and temperature-programmed CO₂ desorption. It has been shown that these catalysts are active and selective with respect to methanol formation at 220-300 °C and a pressure of 40 atm. However, over time, the In₂O₃-CeO₂ catalyst becomes deactivated, while the In₂O₃-ZrO₂ catalyst shows stable performance for at least 10 h.

The properties of the In₂O₃-ZrO₂, In₂O₃-Ga₂O₃-ZrO₂ and In₂O₃-Co₃O₄-ZrO₂ catalysts for the reaction of CO₂ hydrogenation to methanol were studied. It has been determined that with an increase in indium oxide content, the catalytic activity passes through its maximum at In₂O₃ content 10 wt%. It is shown that the introduction of cobalt oxide into the catalyst increases the selectivity for methanol and increases CO₂ conversion. This is due to an increase in the number of oxygen vacancies on the surface of the catalyst. Promotion with gallium oxide, on the contrary, leads to a decrease in activity in the methanol synthesis reaction. Among the series of catalysts studied, In₂O₃-Co₃O₄-ZrO₂ exhibits the greatest activity, which achieves 11.1 % CO₂ conversion with 71 % selectivity to methanol at a pressure of 40 atm and 300 °C. It is also shown that this catalyst operates without a loss of activity for 30 h under these conditions.

The effectiveness of protection and rational use of water resources is reduced due to the difficulties of assessing their quality under the conditions of continuously changing controlled indicators and the uniqueness of such variability. The possibility of solving the arising problems by applying multivariate statistical methods of control, which are common in solving chemometric problems, is considered. By the example of the analysis of the Isakovskoye Reservoir waters (Lugansk People’s Republic), the influence of annual peaks of some pollutants on the increased volatility of the investigated time series was found. The double Schuchart control charts and cointegration tests allowed us to identify the periods of statistical stability of the process and to make an assumption about the active involvement of water pollutants in physical-chemical-biological processes. In particular, the existence of stationary linear combinations of a number of non-stationary (integrated) time series of controlled indicators has been found. The results obtained in the case study of a particular water body show that the methods of chemometrics offer opportunities to obtain the information for deeper understanding of the unique processes occurring in water bodies. This will make it possible to solve one of the main tasks of water-environmental management - to achieve a balance between the needs of water users and the possibility of water resources reproduction by taking optimal water management decisions depending on the current situation.

The content of phenolic compounds (flavonols, flavans (catechins), tannins), polysaccharides (pectins, protopectins), tetraterpenes (carotenoids), as well as the antioxidant and antiviral activity of Solidago canadensis L., Solidago virgaurea L., Bellis perennis L., cultivated in West Siberia has been investigated. The leaves and inflorescences of S. canadensis and S. virgaurea contain about 2 % of flavonols. The total tannin content varies in the inflorescences from 10.59 % (S. virgaurea) to 19.7 % (S. canadensis). The above-ground organs of S. canadensis are characterised by the higher content of catechins (up to 0.19 % in leaves) than S. virgaurea (up to 0.07 % in leaves). Leaves and inflorescences of the studied species of Solidago genus contain no more than 1 % pectins and 10 % protopectins. The concentrations of carotenoids in the leaves and inflorescences of S. canadensis are the same (about 0.1 %), S. virgaurea is characterised by a higher content of this group of compounds in the leaves (up to 0.2 %). The total content of catechins (up to 0.07 %), pectins (up to 0.19 %), protopectins (up to 7.0 %) and carotenoids (up to 0.01 %) in the leaves and inflorescences of B. perennis exhibit no significant differences. Flavonols are present in smaller amounts in the leaves (no more than 6 %), tannins in the inflorescences (no more than 6 %). The total content of phenolic antioxidants in the leaves and inflorescences of S. canadensis, S. virgaurea and B. perennis is within the range of 0.11-0.19 mg/g. The radical binding activity (determined by the DPPH method) of S. virgaurea (1.32-1.61 mg/ml) is two times higher than that of S. canadensis (3.05-3.58 mg/ml) on average. An aqueous-alcoholic extract from the leaves of S. virgaurea inhibits the reproduction of the avian influenza virus A/chicken/Kurgan/05/2005 (H5N1) (neutralization index (NI) is 4.75 lg) and the human influenza virus A/Aichi/2/68 (NI is 4.50 lg).

The problem of neutralising liquid solutions containing hexavalent chromium compounds is considered. The advantages, disadvantages and features of the application of basic methods for neutralising chromium-containing waste, non-traditional approaches and combined technologies are analysed. A readily feasible reagent method is presented for purifying concentrated and dilute solutions from chromium by treatment in two stages: reduction of hexavalent to trivalent chromium using ferrous sulphate or sodium sulphite as reducing reagents, and precipitation of chromium hydroxide. An installation is described in which electrolytes, rinsing and waste water from galvanic production were neutralised. A practical approach to the problem of neutralising the inhibitor solution is proposed, which is similar to the methods used for processing chromium-containing waste from galvanic production. A technological process has been developed for the reagent treatment of an inhibitor with a high concentration of chromates in solution (up to 40 g/L) in one stage by the direct precipitation of poorly soluble chromates. Barium chloride was used as the precipitant. To implement the technology, a schematic diagram of the installation was developed, and appropriate equipment was selected. As a result of processing the inhibitor, waste water, heavy precipitate of barium chromates are formed, which can be used in the future as a raw material, and sludge, which is a non-recyclable waste. Experimental processing of the inhibitor solution shows that the proposed method is effective, economically feasible, readily implementable under industrial conditions, it allows for high purification degree with low consumption of reagents, and reduces the amount of precipitates formed, which confirms the practical significance of the results obtained.

The high-strength nanocomposite cryogels based on polyvinyl alcohol (PVA) and carbon nanotubes (CNTs) have been synthesised and studied. To overcome the problems related to CNTs agglomeration in polar solvents, which limits their uniform distribution over the polymer matrix, cryogel composition was optimised to achieve high strength characteristics. To obtain uniform CNT dispersions, homogenisation in solvents (water, dimethyl sulphoxide (DMSO) and a mixture of DMSO/water = 80 : 20 by volume) in combination with ultrasonic treatment was used. During the experiment, cryogel samples were stretched uniaxially, which allowed us to obtain the ultimate strength values for each sample. Data processing was performed using STATISTICA 10 software. Using regression modelling, the Dependences between the ultimate strength of nanocomposites and synthesis parameters (the concentration of initial PVA solution, its molecular weight, water content in the solvent, and the concentration of CNTs) were established using regression modelling. The obtained regression equation was adequate with respect to Fisher’s criterion, and determination coefficient was R² = 0.81, which confirms the accuracy of the model and its applicability for predicting the strength characteristics of cryogels. In addition to regression analysis, the dependences of the Harrington desirability function on synthesis parameters were analysed. This approach allowed us to identify optimal components ratio for obtaining PVA/CNT nanocomposite cryogels, which significantly increased the efficiency of developing materials with high strength properties. The results of the study emphasise the importance of taking into account various factors when optimising synthesis conditions and also offer new prospects for further research in the area of polymer composites.