Home – Home – Jornals – Chemistry for Sustainable Development 2024 number 6

Vanadium flow batteries (VFB) are becoming widespread as cheap and reliable electric storage cells. In their operating principle, VFB are very similar to fuel cells: they contain a liquid energy carrier (a rechargeable electrolyte) and a stack (a fuel cell in which an electrochemical reaction occurs). For the further development of these systems within the framework of the energy efficiency strategy, it is necessary to increase their efficiency factor, because currently it is only 60-65 %. In the present work, new electrode materials are developed and studied: combined electrodes, allowing a decrease in the internal resistance of the cell (a single element of stack design). To achieve this result, it is proposed to reduce the resistance associated with charge transfer to the electrode surface by creating an active layer with high surface area on the surface of the electrode (felt). The active layer was electrically conductive carbon black CH210, which was pre-functionalized to increase its hydrophilicity (the surface was oxidised in concentrated hydrogen peroxide at elevated pressure and temperature). Electrochemical measurements have shown that the deposition of an active layer increases the cell efficiency factor by 8.6 % at a current density of 50 mA/cm², which confirms the viability of this approach.

The forms of iron occurrence in bentonite clay from the Kaibalskoye-2 deposit were determined using theoretical and experimental methods (elemental analysis, scanning electron microscopy and elemental mapping, powder X-ray diffraction with Rietveld refinement, Mössbauer spectroscopy, UV-vis diffuse reflectance spectroscopy, and quantum-chemical simulations). The total Fe₂O₃ content was found to be 8 wt %, while the montmorillonite content was 65 wt%. No minerals capable of containing significant amounts of iron were detected, however, iron can substitute aluminium isomorphously in the octahedral layers of montmorillonite. The results of scanning electron microscopy with elemental mapping show that a small amount of iron is concentrated as oxide and hydroxide inclusions in quartz and in aluminosilicates. Most of iron is uniformly distributed in the agglomerates of aluminosilicates, which means that iron is included into montmorillonite structure through isomorphous substitution. According to the data of Mössbauer spectroscopy, iron is represented by Fe³⁺ ions in octahedral positions. Absorption bands are observed to appear in the UV-vis diffuse reflectance spectra at longer wavelengths (at 420-600 nm) as a result of iron insertion into montmorillonite structure, which is confirmed by quantum-chemical simulation. Promising directions for the rational use of bentonite from the Kaibalskoye-2 deposit are proposed on the basis of the newly established data.

Experimental acute lung inflammation in mice was modelled by inhalation of lipopolysaccharide aerosol from a Salmonella typhi microbial cell. It has been shown that inhalation aerosol administration of lipopolysaccharide (particle size 1.1±0.1 µm) for 60 min at a dose of 5.3 µg/kg leads to a pronounced haemodynamic and emphysematous reversible change in the lungs after 5-7 days, which is characteristic of acute lung inflammation.

The possibility of selective ion-exchange separation of rare earth elements (REE), in particular La³⁺, from weakly acidic solutions containing an excess of Al³⁺ and Fe³⁺ ions has been demonstrated. The sorption of REEs and Al³⁺ was conducted under static and dynamic conditions using the chelating ampholytic resin Purolite S-930 in the Na-form. Selective REE desorption was performed by washing the column with the aqueous solution of EDTA, while Al³⁺ ions were retained in the column. The conditions for La³⁺ ion extraction were optimized, and the mechanism of their sorption was investigated. Experiments confirmed effective lanthanum extraction at the optimal pH 4.0 and a temperature of 25 °C. An increase in temperature to 65 °C reduces the sorption equilibrium time from 5 to 3 hours at an initial lanthanum concentration of 2.4 mg/L. The effective activation energy of the process was calculated to be 36.9 kJ/mol, and the maximum sorption capacity was determined as 322 mg/g. The influence of EDTA concentration on the efficiency of La³⁺ ion desorption in the presence of Al³⁺ was demonstrated. The developed methodology was applied for the sorption purification of REE-containing technological solution obtained during complex fluoride processing of the spent oil-cracking catalysts. Laboratory-scale sorption purification of this solution yielded a sufficiently pure concentrate (with the total REE oxide content at 85 wt%). Selective desorption from the iminodiacetate ampholyte allows a 30-fold REE concentrating from the technological solution, with losses not higher than 20 %.

Fluorescent conjugates of human serum albumin and a maleimide derivative of monomethyl auristatin F containing the cleavable peptide linker ValCit were synthesised. Strategies included the direct attachment of the peptide to the albumin structure and the attachment of the peptide through the N-trifluoroacetylhomocysteine linker. Confocal microscopy showed that the conjugate with the homocysteine linker effectively accumulated in the cytoplasm of the MCF-7 tumor cells, whereas the conjugate without the linker displayed predominant surface accumulation. In vitro studies demonstrated that the monomethyl auristatin F conjugate exhibited enhanced cytotoxicity against MCF-7 and T98G cancer cells after its attachment to albumin. The homocysteine-containing conjugate showed superior cytotoxicity compared to the conjugate without the linker despite the lower peptide load.

Analysis of data on the chemical composition of groundwater from the water intake of the Novosibirsk Scientific Centre over a long period of operation (1958-2023), including the results obtained at the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, indicates the stability of the macrocomponent composition of groundwater. The results of many years’ hydrogeochemical monitoring of groundwaters from the Beregovoy-1 site, supplying water to most of the buildings in the higher district of Akademgorodok, and from the Zyryanka site from which water is supplied to the cottage area including Akademicheskaya and Zolotodolinskaya streets, as well as Kirov and Geologov settlements, are presented in the work. Water quality is assessed on the basis of actual sanitary rules and norms adopted in the Russian Federation, State Standards and the criteria currently applied abroad. The waters from these sites have hydrocarbonate magnesium-calcium composition with total salt content within the range of 200-400 mg/dm³, total hardness from 3.8 to 7.7 mg-equiv/dm³. A characteristic feature of water from the infiltration water intake of the Beregovoy-1 site is a high iron content (0.11-7.14 mg/dm³), which is 5-20 times higher than the maximum permissible concentration (MPC), and manganese concentration (0.12-0.61 mg/dm³), which exceeds the MPC by a factor of 8 during some years. Arsenic concentration is almost always slightly above the permissible level, and in particular years it exceeded the MPC by a factor of 2 and more. These features predetermine obligatory water treatment before supplying to the population. The waters of the Zyryanka site meet sanitary quality standards, with the exception of radon level, which can reach 130 Bq/dm³.

Gaseous products formed in the pyrolysis of samples composed of the tableted K (coking) and A (anthracite) coal microparticles under the action of pulse-periodic laser radiation (with the parameters: 532 nm, 10 ns, 6 Hz, 0.2-0.6 J/cm²) in the argon environment have been studied. It is shown that the concentration of gaseous products increases exponentially with an increase in the laser radiation energy density. Exceeding the critical radiation energy density values ( H _cr = 0.18 and 0.26 J/cm² for K and A coal ranks, respectively) leads to ablation of coal samples.

The samples of native and naturally oxidised brown coals from the Tisul deposit of the Kansk-Achinsk coal basin, as well as the components isolated from them (humic acids (HA), fulvic acids (FA) and residual coal (RC)) were studied using the method of analytical scanning electron microscopy, proximate and ultimate analysis. It has been found that oxidised brown coal is characterised by an increased yield of HA, FA and volatile substances, ash content, oxygen, nitrogen and sulphur content, with lower concentrations of carbon and hydrogen in comparison with native coal. The HA fractions isolated from coal have a higher carbon content in comparison to FA fractions, but lower oxygen, nitrogen and sulphur content. Electron microscopic studies have shown that natural oxidation significantly affects the morphology of coal particles through their destruction, grinding, rounding and the formation of surface defects. Similar changes in morphology can be partially traced in the particles of HA, FA and RC powders isolated from the oxidized form of brown coal. The surface of oxidised brown coal is saturated with oxygen and enriched with mineral components, mainly consisting of Si, Ca, Fe and Al, in the form of a separate phase and inclusions in the organic mass of coal. For native coal, the content of these elements is significantly lower. The surface of HA, FA and RC powders contains mineral components inherited from original brown coal, as well as large NaCI crystals, which are a by-product of the alkaline extraction process. The RC surface has been determined to contain the increased content of silicon oxides and clay minerals, which are extracted from initial coals at the stages of HA and FA isolation only in insignificant amounts, thus being mainly deposited in RC. In general, the surface of coal derivatives (HA, FA and RC) obtained from oxidised raw materials is characterised by an increased content of oxygen and mineral components in comparison with the surface of native analogues.

The effect of bismuth telluride (Bi₂Te₃) nanoparticles and multi-walled carbon nanotubes (MWCNTs) on thermal destruction and surface morphology of their nanocomposites with polyaniline (PANI) at different nanophase contents (Bi₂Te₃ - 7.3 wt%, MWCNTs - 1.5 wt%), obtained for the first time using the mechanochemical approach, has been investigated. It is shown on the basis of the data obtained by synchronous thermal analysis and scanning tunnelling microscopy that the introduction of inorganic nanophase has a key effect on the thermal properties of the synthesised composites PANI-Bi₂Te₃ and PANI-Bi₂Te₃-MWCNTs, as well as on their structure. The thermal stability of nanocomposites and the initial polymeric matrix, assessed from the temperature of the onset of the second mass loss stage, is the same and equal to 166 °C.

Nanostructured Fе-Pt/С composites based on a carbon matrix with a filler content of 1 wt%, and the molar ratio of Pt/Fe components equal to 9 : 1 have been obtained by the joint reduction of aqueous solutions of the precursors (hydrogen hexachloroplatinate(IV) and iron(II) sulphate) with an alkaline solution of hydrazine hydrate at a temperature of 90-95 ° C. The carbon matrix was mainly a microporous carbon sorbent (CAK) synthesized by the high-temperature alkaline activation of anthracite from the Kuznetsk coal basin. The formation of the Fе-Pt filler nanophase at the initial stages of synthesis has been studied. For this purpose, along with the standard synthesis method (5 min), the syntheses with the interruption of the reaction at the initial stage (after 10 and 30 s) have been carried out by introducing a dilute HCl solution cooled to a temperature of 2 °C into the reaction medium. It has been found that, according to X-ray diffraction and sorbtometry data, the formation of finely dispersed filler nanoparticles decorating the matrix surface occurs within the first 10 s, while minimal blocking of the matrix pores is observed, and the highest electrical capacity characteristics for nanocomposites are recorded. It has been determined that with an increase in process duration, the filler particles become larger, which causes a decrease in the specific surface of nanostructured composites and, as a consequence, deterioration of the electrical capacitance properties. It is shown that the highest specific electrical capacitance (1.5-1.7 times higher than the capacity for a cell with electrodes made of CAK) was achieved in an asymmetric cell with a working nanocomposite Fе-Pt/C electrode obtained under the conditions of synthesis interruption after 10 s. The reasons for these considered effects are discussed

The effect of preliminary heat treatment of medium-temperature electrode pitches on the yield of carbonisate is investigated. The objects of investigation were electrode pitches: B-grade pitch (Altai-Koks JSC, Zarinsk), B1-grade pitch (Evraz ZSMK JSC, Novokuznetsk). The pitches were treated by heating with further thermostating at 300 °C for different time intervals. For medium-temperature pitches, the dependences of the yields of heat treatment products, the yield of volatile substances, softening temperature on process duration were determined. It has been found that an increase in the softening point value proceeds at a higher rate in the case of B-grade pitch treatment than for B1-grade pitch, which may be due to a more intense decrease in the yield of volatiles for B-grade pitch in comparison with B1-grade pitch. It has been shown that after the heat treatment of the pitches, the content of α-fraction (the substances insoluble in toluene) in the final product increases by 46.8 % in the pitches of both grades. The dependence of carbonisate yield on the duration of the heat treatment of the pitch has been determined. It is found that preliminary heat treatment of pitch at 300 °C for 5 h allows an increase in the yield of carbonisate by 5 %. It is shown for the first time that the yield of carbonisate for B1-grade electrode pitch is higher than for B-grade electrode pitch, which correlates with the higher content of α₁-fraction (the substances insoluble in quinoline) in the former. This dependence is also retained for heat treated pitches. For the first time, the dependence of the yield of volatile substances in carbonisates on the duration of heat treatment of pitches was established.

The results of chemical, proximate and petrographic analysis of coal samples at different coalification stages from various deposits in Russia and Mongolia are presented. Features of the molecular structure of the carbon framework in the organic matter were studied by the solid-phase ¹³C NMR spectroscopy using the cross polarization with magic angle spinning (CP/MAS). Significant differences in the structure of polycondensed aromatic nuclei were revealed, and the ratio between the pericondensed and catacondensed cycles depending on the degree of coalification was assessed. Correlation analysis has been carried out and the relationships between various chemical technological parameters of coals and the indicators of their molecular structure were established. The strongest relationships have been revealed between the aromaticity factor of coals, the fraction of carbon in pericondensed structures, the yield of volatile substances and the reflectance of vitrinite. The identified features of the molecular structure of the organic coal matter and the obtained regression dependences can serve as the physicochemical basis when selecting coals for obtaining polycondensed aromatic substances for the production of carbon materials.

The possibility of making electrode nanocomposite materials for supercapacitors by adsorption of transition metal salts from aqueous solutions by the porous carbon matrix with subsequent heat treatment has been investigated. It is shown for the carbon - Co₃O₄ system as an example that this method allows obtaining nanocomposites with the content of filler (elemental cobalt) up to 3 wt%. The introduction of the filler using this method only slightly reduces the specific surface area and pore volume of the composites with respect to the initial carbon matrix. The product obtained by thermal decomposition of cobalt(II) nitrate at 240 ^oC cannot be identified by X-ray diffraction, but according to the data of differential thermal analysis, it catalyses thermal oxidation of the porous carbon matrix in air. It is shown by cyclic voltammetry that the electrode materials obtained by the adsorption method have a higher specific capacitance compared to the original carbon matrix or composites obtained by inserting the filler as the solid phase.

The use of coal from the Mezhegey deposit (the Republic of Tyva) is promising for the production of thermal energy. However, it is necessary to consider the peculiarities of the technological properties of coal associated with its increased sintering characteristics. These features with the layered coal combustion technology lead to excessive consumption of fuel due to its underburning and a high content of harmful substances in the flue gases. Kyzyl has already been included in the Federal Project “Clean Air”, which indicates the relevance of the present investigation and the necessity of introducing new methods into the usage of this energy resource. To reduce emissions and to enhance the efficiency of coal use in power engineering, it is reasonable to introduce the technology of obtaining and burning coal-water fuel (CWF) taking into account the specific features of coal. The possibility of obtaining and using environmentally friendly coal-water fuel from the coals of the Mezhegey deposit located in the Republic of Tyva is established. The technical characteristics of coal were analysed, a pilot batch of CWF was obtained, and the combustion characteristics of this fuel in a boiler plant were determined. The preparation and combustion of the pilot batch of CWF was carried out in the laboratory installation at the Siberian State Industrial University (Novokuznetsk). It has been shown that the concentrations of hazardous substances in flue gases are substantially lower than the maximum permissible values. The development of this technology involving coal from the Mezhegey deposit will make it possible to reduce fuel consumption at heat generating installations and minimize the negative environmental effect.

The possibility of using nitrogen-containing carbon nanotubes (N-CNTs) as a support for the synthesis of single atom palladium and platinum catalysts has been studied. The influence of metal content (0.2-2 wt%) and synthesis method (impregnation and deposition) on the dispersion of supported Pd and Pt was studied. The requirements for preparation of a 100 % single atom catalyst have been determined (use of a metal precursor in cationic form and a metal content of less than 0.5 wt%). It was established that the turnover frequency of the gas-phase formic acid decomposition reaction for hydrogen production increases by 4 times on single metal atoms stabilised on the pyridinic nitrogen centres of the N-CNTs, compared to nanoparticles with a size of ~1 nm. Single atom metal catalysts exhibit higher selectivity to hydrogen and make it possible to decrease the concentration of carbon monoxide by more than 2 times. The stability of Pd and Pt atomic species in the course of the reaction occurring at elevated temperatures has been established.

A systematic study of the compositions of individual particles smaller than 10 μm in size (PM₁₀) in the dispersed fraction of fly ash from the pulverised combustion of lignite from the Kansk-Achinsk basin has been carried out by scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS). It is established that microspheres and particles of nonspherical shapes, belonging by size to the class of environmentally hazardous suspended particles PM₁₀, depending on the content of CaO, SiO₂, Al₂O₃ and Fe₂O₃, form several groups in the formation of which different mineral precursors are involved. A significant part (64 %) of dispersed particles is characterised by high CaO content ranging from 40 to 68 wt%, about 1/3 of the particles contain increased amounts of aluminosilicate components (SiO₂ and Al₂O₃) up to 82 and 40 wt%, respectively, and ~3 % of the particles exhibit high iron content (Fe₂O₃) within the range of 34-65 wt%. A comparative analysis of the relationship between the concentrations of macrocomponents in the form of dependences [SiO₂] = f[Al₂O₃] and [SiO₂ + Al₂O₃] = f[CaO + Fe₂O₃ + MgO] allows us to state that the main mineral precursors of environmentally hazardous suspended particles PM₁₀ formed during lignite combustion are complex Ca,Mg,Fe-humates, feldspars, mostly anorthite, mica-like minerals of chlorite type, and quartz. During lignite combustion, feldspar and mica melt forming the glass phase. After humate oxidation, organically bound Ca, Mg and Fe form highly reactive oxides readily reacting with each other and SiO₂, to be included in aluminosilicate glass with the formation of complex compounds of different composition: silicates, aluminosilicates, aluminoferrites.

The rheological (structural-mechanical) properties of gel-forming compositions, gels and cryogels based on polyvinyl alcohol, as well as the compositions developed at the Institute of Petroleum Chemistry SB RAS, which are promising from the viewpoint of preventing endogenous fires and intensifying methane release during interval hydraulic fracturing of coal seams, have been studied. The amplitude and kinetic dependences of the elastic modulus ( G' ), loss modulus ( G'' ) and complex viscosity were obtained in the oscillatory mode using the rheometer with controlled deformation for the compositions differing from each other in the ratio of components at different temperatures. It has been shown that the gel starts to form already at the moment of component mixing, and the elastic properties of the forming structure predominate ( G' > G'' ). The values of gelation points were determined. It is found that with an increase in crosslinker concentration, the strength of the resulting structure increases, and the time of gel formation decreases. As the temperature decreases, the strength of the resulting structure also increases. In the static mode of sample deformation, it is established that the gel is further stabilised after the freeze-thaw cycle. The developed composition has strength properties and good adhesion to the surface of coal. It can be used to protect coal mine faces from spontaneous combustion and as a protection from coal dust on technological roads. The change of the deformation-compression dependence under constant load on time for gel and cryogel was studied. It has been established that under a constant stress of 7 kPa, gel deformation reaches 25 %, while cryogel deformation is 15 %, that is, the elastic properties of the composition increase after a freeze-thaw cycle. In this regard, it is preferable to carry out the work at sites in the autumn and spring time.

For the development of many regions of Russia, Kazakhstan, China, Mongolia and other countries interested in using their non-conventional hydrocarbon resources (sapropelite coals and oil shale, microalgae biomass), a new strategy is being considered for the development of nature-like technologies for their processing, as well as exploration and production of hard-to-recover shale hydrocarbons through technologisation of the discovery of the regularity of hydrothermal naphthoidogenesis. The main thing in this discovery is that in hydrothermal fluids (sub- and supercritical aqueous media) it is possible to purposefully carry out molecular disassembling of the organic matter of sapropelite rocks and lipid-enriched microalgae into organic compounds that retain the structural features of the original fragments of organic mass and to a large extent are related to biomarker compounds. These biomarker compounds are reliably identified by modern chromatographic and spectral methods, so it becomes possible to monitor the information about the relationship between the genesis, composition and structure of the organic mass of sedimentary rocks and their properties. This information is important for the development of highly efficient methods for producing shale hydrocarbons. It is also applicable for molecular diagnostics of the hydrocarbon-generating potential of sedimentary basins by assessing the lithogenetic maturity of rock organic matter from the composition and content of biomarker compounds. It is expected to obtain technologically significant results in increasing the efficiency of processing non-conventional hydrocarbon resources due to the possibility of controlled selective cleavage of carbon-carbon and carbon-heteroatom cross-links in the organic mass of microalgae and oil shale rocks under oxidative hydrolytic conditions similar to those that occur in natural, environmentally pure processes of naphthoidogenesis. The need to expand and deepen the studies aimed at technologising the scientific discovery of the regularity of hydrothermal naphthoidogenesis, which is the basis for the development of nature-like technologies for processing non-conventional hydrocarbon resources into valuable chemical products (motor fuel components, surfactants, etc.) and materials (road construction bitumen) is substantiated.