Home – Home – Jornals – Chemistry for Sustainable Development 2024 number 4

The influence of the main hydrochemical parameters, ionic and elemental composition of natural waters with different anthropogenic loads on the efficiency of photocatalytic processes is investigated for the oxidation of model organic pollutants: azo dye (methyl orange, MO), phenothiazine dye (methylene blue, MB). Comparative studies of water quality in two small rivers located within the boundaries of Khabarovsk (the Krasnaya River) and beyond (the Polovinka River) from April to October 2023 were carried out using the methods of chemical analysis, mass spectrometry with inductively coupled plasma and spectrophotometry. It was shown that the highest concentrations (>5 mg/dm³) were observed for ions (HCO₃^-, Cl^-, SO₄^2-) and elements (Na, Ca) in rivers draining urban areas (large highways, industrial enterprises, residential areas) and suburban territories (agricultural lands, country house areas). The efficiencies of photocatalytic destruction of anionic (MO) and cationic (MB) model pollutants dissolved in distilled water, water from small rivers, distilled water in the presence of Na⁺, HCO₃^-, Cl^-, SO₄^2- ions were compared. The time of photodestruction was assessed for model pollutant transformation degree equal to 90 % at the final stage of photocatalytic experiment. The degree of reduction in the efficiency of photocatalytic processes when conducting experiments in waters from small rivers was assessed with respect to the experiment in distilled water. The time of photodestruction of samples from real water bodies (at the degree of pollutant transformation 90 %) was demonstrated to increase with respect to the experiment in distilled water by a factor of 4.8-7.3 (MB) and 1.9-4.7 (MO) for the samples from the Krasnaya river, 3.7-6.3 (MB) and 1.1-2.2 (MO) for the Polovinka river. Value scattering was due to the seasonality of sampling.

A compacted matrix of boron carbide has been infiltrated by molten aluminum. It is shown that under the external mechanical action on aluminium, presumably simplifying the destruction of oxide film on molten metal, the temperature of boron carbide wetting decreases from 1100-1200 to 830-850 °C, and this prevents the formation of unfavourable aluminium carbide that could worsen the mechanical properties of composite material. Dense ceramic composites with the density within the range of 2.45-2.58 g/cm³, Vickers hardness up to 21 GPa and fracture toughness at a level of 3.5-4.5 MPa · m^1/2 have been obtained. It has also been determined that, although carbon nanotubes react with molten aluminium, a considerable amount of them is preserved during infiltration at temperatures below 950°С, which allows one to synthesise the соmposite material reinforced with nanotubes.

Traditional and new methods of the production of ammonium sulphate and complex salts based on it are considered. The problem related to the sales of many wastes and by-products of metallurgical enterprises, in particular technical-grade ammonium sulphate formed in the by-product coking department of JSC ArcelorMittal Temirtau that could become the secondary raw material basis to manufacture marketable products, has not been solved yet. Alternative methods of obtaining ammonium sulphate from industrial, agricultural and animal farm wastes are presented, along with various areas of its application. Relevance of the production of complex salts based on ammonium sulphate and the possibility to increase its consumption in agriculture by obtaining complex salts with decreased acidity and increased content of useful components are demonstrated. The new possibilities of sulphate ammonium application and the potential of its application as a reagent for the production of anhydrous sodium carbonate and ammonium hydrofluoride are proposed.

A technology for thermolytic processing of fuel oil over a tin-lead melt in a flow-type reactor is proposed. Methods for fuel oil processing at oil refineries are currently too complicated and cost-demanding, so the development of effective technologies for fuel oil processing is an urgent task. The main advantages of the proposed technology are rather low process temperature and pressure close to atmospheric. The technological parameters of the process are constant over all points of the reactor, which ensures high-quality products. The formation of carbon deposits on the reactor walls is essentially eliminated. The technological process occurs simultaneously with auxiliary and transport operations, which increases the productivity of the installation. It becomes possible to completely automate technological process, eliminating the use of manual labour and simplifying installation maintenance. A schematic diagram of the flow-type installation is presented. The results of experiments on the thermal cracking of fuel oil over a tin-lead melt, carried out using two versions of destructive distillation, are presented. The first version involves minimal withdrawal of thermal gas oil (31 %), while in the second version it is maximal (77 %). It has been shown that the content of gasoline fraction (b.p.-180 °С, where b.p. is initial boiling point) and diesel fraction (180-360 °С) in the thermal gas oil obtained according to the second version is lower than that obtained according to the first version. Thermal gas oils have a high content of aromatic compounds, which makes them a promising raw material for the production of needle coke.

The modern market of paint and varnish materials is represented by a wide range of construction products, including those designed to protect facades of buildings and structures from atmospheric impact. Among the variety of varnishes and paints for processing and rendering decorative and protective properties to building materials, as well as from the viewpoint of environmental friendliness, the most popular products are water-dispersion paints based on acrylic dispersions. However, along with the high values of colour fastness, UV resistance and gas permeability, acrylic-based paints are insufficiently elastic and lack resistance to water. In this regard, the paper considers a method for increasing the mechanical and hydrophobic properties of acrylic paint and varnish material by introducing a hydrophobic polyethylhydrosiloxane-based emulsion containing polyethylhydrosiloxane (PEHS) - 35.20, glutaric aldehyde - 0.19, polyvinyl alcohol (PVA) - 7.75, water - 56.86 wt%, as well as by increasing the surface development (relief), achieved by increasing the volumetric concentration of pigments (VCP). The optimal range of the amounts of a hydrophobic emulsion and a coalescent into the composition of water-dispersion paints based on acrylic dispersion has been determined. To assess the stability of the coating after drying of an aqueous dispersion paint modified with the aqueous polyethylhydrosiloxane emulsion, the wetting angle and free energy of the surface were evaluated using two liquids of different polarities, namely distilled water and diiodomethane. The possibility of modifying the aqueous dispersion paint, characterised by VCP of 70-80 %, by the polyethylhydrosiloxane hydrophobic aqueous emulsion in the amount of 5-5.5 %, combined with ethylene glycol (4.5-5.5 %) has been established, which makes it possible to obtain a hydrophobic coating with a wetting angle of up to 100°. By comparing the wetting angle values of the coatings, it has been shown that in the absence of the hydrophobic additive, this parameter is lower by 12.5 % than the parameter of the modified sample.

Despite the increasing contribution of integrated approaches to processing waste from the forest industry and crop production, the main method of recycling plant wastes is still combustion, which leads to losses of valuable substances. An alternative and advanced way of plant waste processing is extraction to obtain useful substances. The previously published data on the extraction-based methods to isolate valuable substances from wood waste and straw of various crops under industrial and laboratory conditions are generalised in this work. The data on the chemical composition of wastes from forest industry and crop production, as well as on the content of chemical compounds of practical significance are systematised. The basic approaches to retrieve such valuable components as lignin, furfural, waxes, organic acids, polyphenols, dyes, silicon dioxide and others from plant wastes are described.

The electronic effects of xenon-containing substituents XeY, [Xe⁺] and [XeF₂⁺] in different solvents were calculated using the ¹⁹F NMR method. The results obtained allow us to classify these substituents as the strongest σ-electron acceptors due to the strong positive inductive effect, while the resonance effect is small.

2,5,5-Triethyl-2-alkynyl-3,4-bis(hydroxymethyl)pyrrolidine-1-oxyls (alkynyl = C≡CR, and R = H (2), C(Me)₂OH (1), Ph (7)) undergo cyclisation on heating with sodium hydroxide to form cyclic vinyl ethers, the derivatives of 6-methylene-hexahydro-1 H -furo[3,4-b]pyrrole-1-oxyl. A bicyclic radical derived from radicals 1 or 2 is capable of reversible addition of alcohols to the vinyl group in the presence of acids. Cyclisation of radical 7 in the acid environment in the presence of mercury acetate follows a different route, with the formation of 2,2,7a-triethyl-3-(hydroxymethyl)-6-phenyl-1,2,3,3a,4,7a-hexahydropyrano[4,3-b]pyrrole-1-oxyl.

Aldonitrones of pyrroline series are widely used in organic synthesis, in particular in the synthesis of alkaloids and other biologically active compounds, and as spin traps for short-lived radicals. A three-component domino process involving glycine benzyl ester, ketones (cyclohexanone and diethyl ketone) and fumaric acid esters was used to synthesise aldonitrones of the pyrroline series of 1-pyrroline-1-oxide. The benzyl esters of 3,4,5-substituted prolines obtained in the first step were selectively cleaved by hydrogenolysis. Oxidation of the resulting cyclic amino acids in the tungstate - hydrogen peroxide system is accompanied by decarboxylation and leads to the formation of 3,4,5-substituted 1-pyrroline-1-oxides. It is shown that the ester groups in these compounds can be reduced to hydroxymethyl ones by an excess of lithium aluminum hydride, and subsequent treatment with manganese dioxide leads to aldonitrone group recovery.

An optimised method of 1,1-difluoronaphthalen-2(1H)-one hydrodefluorination leading to the formation of fluoronaphthol under mild conditions is proposed. The palladium-catalysed process is shown to involve carbonyl reduction followed by subsequent hydrogen fluoride (HF) elimination. The structure of the intermediate product and the effect of catalyst support material on hydrodefluorination selectivity have been determined.

Chelators based on terpene bis(α-amine oximes) applied onto low-polar sorbents (coal, Sibunit, Polysorb) are effective selective extractants for the extraction of palladium and gold from acidic aqueous solutions containing the mixtures of precious metals and 3 d-elements. The use of sorbents impregnated with the new chelators allows extraction in the liquid-solid mode without using any organic solvent.

The composition of the lipophilic components of Euphorbia virgata Waldst. et Kit. has been studied. Acidic and neutral components have been identified using gas-liquid chromatography with mass spectrometric detection (GC-MS) following alkaline hydrolysis of the whole extract. The plant material was extracted with methyl tert -butyl ether (MTBE). Total acids isolated during sample preparation were analysed after methylation with diazomethane. The composition of the neutral components of unsaponifiable residue was studied without derivatisation, but after separation by column chromatography on silica gel into the groups of substances of different polarity. As a result, aliphatic acids with the chain length 10-30 carbon atoms, including unsaturated ones, were identified by comparison with databases. In addition, two compounds rarely occurring in plant materials were detected: ricinoleic and octadeca-9-en-12-ynic acids. More than 100 triterpene and aliphatic compounds of the unsaponifiable residue and 25 components of acidic fractions were identified. The hydrocarbon fraction was determined to contain, in addition to n- alkanes, also substantial amounts of unsaturated branched hydrocarbon squalene. Highly active triterpene alcohols and ketones are mainly represented by ursane, lupane and cycloartane derivatives. The main sterol component (β-sitosterol) is accompanied by cholesterol, campesterol, stigmasterol, stigmast-7-en-3-β-ol and stigmastan-3-β-ol. A substantial contribution from euphanic compounds characteristic of the plants of the Euphorbiaceae family has been revealed.

The qualitative composition of lipophilic secondary metabolites in the medicinal plant leuzea safflower ( Rhaponticum carthamoides (Willd.) Iljin) has been studied by gas chromatography - mass spectrometry. The roots and rhizomes of this plant species were used as the raw material. Hexane and methyl tert -butyl ether (MTBE) were used as extractants. Two extraction schemes were used (exhaustive and sequential), which allowed us to obtain more detailed information on the composition of components of the raw material. The obtained lipophilic extracts were separated into acid and neutral components by treating with NaOH and KOH solutions. The acid components were transformed into methyl ethers by treatment with diazomethane. The neutral components of the unsaponifiable residue were analysed without derivatisation. The fractions enriched with hydrocarbons, ketones, sterols, aliphatic and triterpene alcohols were obtained by chromatographic separation through a column with silica gel. A series of low-polar compounds were identified that have not been detected previously in this kind of raw material. By comparing the mass spectra obtained in the work with the available databases, the following compounds were identified: aliphatic acids with chain length 10-30 carbon atoms (including unsaturated and dicarboxylic), the compounds of cinnamic series, as well as benzoic, salicylic, sterculic, 9,10-octadecadienic and phenylpropanoic acids. More than 90 triterpene and aliphatic compounds of the unsaponifiable residue and 33 components of free and bound acids were identified. In addition to n- alkanes, the hydrocarbon fraction contains also squalene, as well as saturated and unsaturated hydrocarbons with shorter chains. Aliphatic and terpene aldehydes and ketones were detected. Highly active triterpene alcohols and ketones are represented mainly by ursane and oleanane derivatives. The major sterol component (β-sitosterol) is accompanied by cholesterol, campesterol, stigmasterol, stigmast-7-en-3-β-ol and stigmastan-3-β-ol.

A series of ureas containing adamantane and monoterpenoid residues has been synthesised. All compounds were tested in vitro using a pseudoviral system containing the S glycoprotein of the SARS-CoV-2 virus and infectious SARS-CoV-2 viruses of various strains on its surface. Compound 4a demonstrated high activity against four strains of SARS-CoV-2.

2-[4-(2-Methacryloyl)-piperazine-1-ylmethyl]-9 H -thioxanthen-9-one-S,S-dioxide 1, an electrochemically active monomer, has been synthesised from 2-(piperazine-1-ylmethyl)-9 Н -thioxanthen-9-one-S,S-dioxide and methacryloyl chloride. Subsequent radical copolymerisation of the synthesised compound with methylmethacrylate leads to an electroactive copolymer (PMMA-co-ThxSO₂) with the ratio of methyl methacrylate fragments in the chain to the pendant (side) groups of the 9 Н -thioxanthen-9-one S,S-dioxide structure equal to 95 : 5, respectively. It has been shown by cyclic voltammetry that the electrochemical reduction (ECR) of 1 in acetonitrile (MeCN) is a two-electron and two-stage process, with the formation of long-living radical anion at the first one-electron stage and unstable dianion at the second stage. Electrochemical reduction of PMMA-co-ThxSO₂ is due to the reductive electrochemical activity of the pendant groups, and its mechanism is similar to the ECR of monomer 1. This compound is a polymer with pendant groups that play the role of efficient electron traps during charge transport inside the thin copolymer film, and it can be used in the resistive memory technologies (ReRAM - Resistive Random Access Memory) as the active working layer of memristors.

The areas adjacent to open coal mining facilities are affected by different kinds of anthropogenic impact, including dust pollution. To reveal the extent of technogenic impact, the parameters characterising the content and composition of 19 priority polycyclic aromatic hydrocarbons (PAHs) in chernozem soils adjacent to the haul road of the Gorlovo anthracite deposit (the Novosibirsk Region) were assessed. It is shown that the maximum total concentration of PAHs (>1000 ng/g) is reached at the distance of 100 m from the source, while the levels higher than the background are detected at a distance of 1000 m. The effect of dominating wind direction and the presence of tree shelter belts were determined to affect the total PAH content in soil but leave their group composition unchanged at a distance of 2000 m from the road. At the same time, the individual composition of PAHs in soils changes with an increase in the distance from the pollution source. The concentration of benz(a)pyrene and total PAH content, calculated for benz(a)pyrene toxic equivalents, were determined in the soils of territories adjacent to the haul road and compared with the current standards in force in the Russian federation (SanPiN). Statistical processing of the results, performed by the principal component analysis, shows that the input of black carbon in the form of anthracite coal dust into soil is most adequately represented by polyarene ratio PHE/(PHE+CHR), where PHE is phenanthrene, and CHR is chrysene. However, the threshold of technogenic load (<0.8), that was previously established for objects in which anthracite is the main source of PAHs, requires confirmation for black soils.

[1]Benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives attract attention in the field of organic optoelectronics due to their stability in air, 2D film formation ability and high charge-carrier mobility. Here we present approaches to the synthesis of new furanyl-substituted BTBT derivatives. The physicochemical properties of the target compounds were studied. It is shown that all materials have high quantum yields of photoluminescence. A thorough analysis of BTBT bromination has been carried out, and the reaction conditions were optimised. It has been shown that a mixture of regioisomers is always formed in this process, but this does not necessarily interfere with further synthesis. A significant reduction in the total reaction time from 48 to 6 hours has been achieved.

Modern trends in the development of structural biology make it relevant to study the structure of biomolecules under the conditions close to natural, i.e., directly in a living cell and at temperatures close to physiological ones. One of the promising technologies that allows approaching this ideal is the targeted introduction of spin labels (for example, nitroxides), followed by investigation using pulsed electron paramagnetic resonance (EPR). Today, the greatest stability in living systems is demonstrated by sterically hindered nitroxyl radicals of the pyrrolidine series with four ethyl groups at a paramagnetic centre, but their relaxation characteristics do not allow measurements by pulsed ESR methods at a temperature above 80 K. Nitroxides with spirocycloalkane fragments surrounding the nitroxyl group are suitable for measurements at higher temperatures, but they are rapidly reduced by the components of living systems. Pyrrolidine nitroxides with two spiro-(2-hydroxymethyl)cyclopentane moieties combine high resistance to reduction with high spin relaxation times at a temperature of 120 K and above. In this work, a hydrophilic chiral radical of this series - (1 R ,5 S ,7 S ,8 R ,12 S ,13 S )-12,13-dihydroxy-1,8-bis(hydroxymethyl)-6-azadispiro[4.1.4.2]tridecane-6-oxyl was obtained and characterised by us for the first time.

The synthesis of ((9 H -(4,5-diazafluorene)-9-ylidene)methyl)arylenes is presented and their physicochemical characteristics are studied by cyclic voltammetry and optical spectroscopy. The target compounds were synthesised from commercially available reagents in three steps using a combination of Suzuki-Miyaura cross-coupling and condensation reactions. It was found that the compounds had a low photoluminescence quantum yield in solution, and 9-(4-([2,2'-bithiophen]-5-yl)phenylidene)-9 H -4,5-diazafluorene demonstrates aggregation-induced luminescence. The crystal structure of 9-(4-([2,2'-bithiophen]-5-yl)phenylidene)-9 H -4,5-diazafluorene was solved by X-ray diffraction analysis. The single crystals of this compound have the elongated plate morphology and exhibit photoluminescence quantum yield of 5 %.