Home – Home – Jornals – Chemistry for Sustainable Development 2021 number 5

The samples of humic preparations (HP) containing macro- and microelements of plant nutrition were obtained on the basis of humic acids (HA) isolated from brown coal of the Tisul deposit of the Kansk-Achinsk coal basin. The biological activity of humic preparations was tested under laboratory and field conditions on stony and loamy soils using the seeds of high-quality wheat varieties ‘Iren’ and ‘Novosibirskaya 89’. A comparative assessment of the influence of the content of microelements cobalt, manganese, copper and zinc in humic preparations on the growth parameters of wheat was carried out. It is shown that the effectiveness of the use of humic preparations depends on the concentrations of all components, the method of their introduction, as well as on the edaphic properties of soil substrates.

The granulometric and morphological composition of fine coal powders prepared according to a special technique for the size classes -0.2 +0.1, -0.1 +0.063, -0.063 +0.04, -0.04 mm from ten different grades of coal (B, D, G, Zh, K, KS, OS, SS, T, A) of the Kuznetsk coal basin was investigated. Technical and elemental analysis, petrographic studies were carried out with the coal samples using standard methods. The set of values of the reflectivity of vitrinite, the sum of the fusenized components, the thickness of the plastic layer and the yield of volatile substances allowed us to establish the grade identity of the studied samples in accordance with the unified classification of coals on the basis of genetic and technological parameters. According to the results obtained by SEM, changes in the structure of coals and the relief of the fracture surface pattern are observed in the series of metamorphism of the studied coal samples from brown coal to anthracite. The granulometric composition of coal powders was determined by laser diffraction when the samples were dispersed in an aqueous medium with the addition of a surfactant. The particle size distribution in coal powders of the fraction -0.04 mm for all grades of coal is characterized as monomodal, in the fractions -0.063 +0.04 mm - as monomodal asymmetric, in fractions -0.1 +0.063 and -0.2 +0.1 mm - as bimodal. These fractions contain irregularly shaped particles (needle-shaped, oval), as determined by means of SEM. According to the results of the studies of KS grade coal by means of NMR spectroscopy, it is established that the content of aliphatic carbon (CH₃) in the samples increases insignificantly with a decrease in the size of the coal powder fraction - from 3.05 % for the fraction -0.2 +0.1 mm to 3.73 % for the fraction -0.04 mm. The values of the aromaticity index f _a for all fractions remain constant.

Features of phase formation and properties of solid solutions in the nanostructured FePt system synthesized by reducing the aqueous solutions of precursors by hydrazine hydrate are considered. It is established by means of X-ray diffraction studies and elemental analysis involving optical emission spectroscopy that limited solid solutions with the fcc type structure are formed under the conditions of the samples with the component ratio Pt/Fe ≥ 0.5. With iron content ( С _Fe) ≤ 11.6±0.7 at. %, the system is monophase (an fcc-solid solution), with higher iron content it is composed of two phases (an fcc-solid solution with С_Fe = 11.6±0.7 at. % and a diffraction-invisible phase relatively enriched with iron). The size of the coherent scattering region for the solid solution varies from 7 to 9 nm. The presence of Fe³⁺ was revealed in all samples by means of electron paramagnetic resonance. Small amounts of iron hydroxide and oxides were detected by means of XRD in the samples with a high iron content. The temperature regions of O₂ and CO₂ desorption, thermal decomposition of extrinsic FeO(OH) and crystallite agglomeration accompanied by phase transformations were determined in the studies of thermally stimulated processes.

The properties of the coals of Tuva and Mongolia are considered for the purpose of organizing the processing technology for the production of coal smokeless briquettes that reduce the formation of smog and air pollution from private houses with coal heating. Experimental and industrial thermolysis units have been developed and manufactured for conducting research works aimed at the production of smokeless fuel. Fuel briquettes were obtained by pressing the solid products of coal thermolysis (semi-coke) at an elevated temperature in the periodic mode on hydraulic presses in Russia and Mongolia.

The structural, morphological and electrochemical properties of nanocomposite materials of the type of a highly porous carbon matrix filled with Co₃O₄ are investigated. The effect of the filler preparation method (thermal decomposition of cobalt (II) hydroxide or cobalt (II) azide) in matrix pores on the characteristics of composites was considered. The composition, morphology, phase compositions of the composites, the stoichiometry of fillers, disperse and porous structures, as well as electric capacitance characteristics of the carbon matrix, precursor composites and nanostructured C/Co₃O₄ composites were studied using various physicochemical methods. It is established that the composites are formed through the deposition of nanoparticles of filler precursor and, during their thermal decomposition, of the target filler Co₃O₄ in the pores of three size groups (2-3, 7-12, and ~20 nm), and through the formation of the aggregates of filler particles on the external surface of the matrix. The nature of the effect of filler on the electric capacity of the composite depends on the method of composite formation: the capacity decreases in the composites obtained by thermal decomposition of Co(OH)₂ precursor and, quite contrary, increases in the composites formed by thermal decomposition of Co(N₃)₂. This feature, discovered for the first time, may be related to the effect of the method of composite preparation on filler stoichiometry (the Co²⁺/Co³⁺ ratio) as determined by X-ray diffraction: the deviation of the stoichiometry from the formula-based relations between CoO and Co₂O₃ proceeds towards an increase in CoO fraction when the azide precursor is used, and towards an increase in the fraction of Co₂O₃ when the hydroxide precursor is used.

The results presented herein were obtained by the scientists from Kazakhstan in research areas concerning the manufacture of carbon fibres by means of electrospinning from coal tar pitch and polyacrylonitrile, making coke from heavy oil residues, investigation of the composition and structures of asphaltenes extracted from the natural bitumen of the Munayly-Mola deposit. The precursor for carbon fibres was coal tar, a by-product of the treatment of coal from the Shubarkol deposit. The physicochemical characteristics and the composition of coke obtained from goudron at the Pavlodar petrochemical plant as a result of preliminary demetallization and desulphuration are demonstrated. It is established that the structure of asphaltenes from natural bitumen is more ordered and non-amorphous.

The correlation between the energy threshold of laser ignition of coals and the degree of their aromaticity was investigated. The ¹³C CPMAS NMR spectra of different marks of coal were recorded. Quantitative data on the distribution of carbon over structural fragments were obtained from these spectra with the help of modeling. It is shown that an increase in the rank is accompanied by an increase in the intensity of the signals of aromatic carbon and a decrease in the intensity of aliphatic carbon signals. In addition, with an increase in the rank, the content of CH₂, C-O-C, COOH functional groups in coal decreases. The direction of the correlation between the energy threshold of ignition of hard coals and the degree of their aromaticity was determined, and the strength of the correlation was established.

Samples of the composition CeCuO_1.5/C (C = Sibunite, C-Al₂O₃, Taunite, oxidized Taunite) were prepared by incipient wetness impregnation in order to develop new catalysts based on supported bimetallic oxide nanoparticles for oxidative transformations of sulphur compounds. Using FTIR spectroscopy and thermal analysis in combination with mass spectrometry, the effect of the nature of the support and its oxidative treatment on the functional composition of the support surface and its thermal stability was studied. Among the supports studied, the sample on Taunite proved to be the most stable to decomposition. The thermal stability of Taunite decreases after oxidative treatment and the introduction of metal precursor salts.

The results of the studies aimed at the improvement of the mode of flotation of flocculated coal due to the application of Sinterol, a new modifying reagent, are reported. Coals from the basins of the Russian Federation with different degrees of organic mass mineralization were used as the initial coal samples. When applying the modifying reagent Sinterol in the amount of (1-3) · 10^-3 kg/t and simultaneously reducing the total consumption of reagents by 13.0 % on average (from 3.000 to 2.613 kg/t), the concentrate yield increased by 2.5-8.5 %, the ash content of the concentrate decreased by 2.7-3.0 % the extraction of combustible mass into the concentrate increased by 2.9-7.1 %. The ash content of the waste increased by 2.9-12.3 % and was in the range of 72.6-82.0 %. A decrease in the ash content of the concentrate and an increase in the ash content of the waste with an increase in the modifying reagent input are explained by the flocculating effect of the reagent on the mineral particles of the pulp, which is important for flotation of hard-to-enrich coal fines containing a large amount of clay substances. The efficiency of the Sinterol flocculant reagent at its low consumption was revealed. The reason is the prevailing enlargement of the particles of mineral impurities and a decrease in their floatability together with the organic mass of coals.

Humic acids are highly oxidized organic compounds originated from plants and coals. Therefore, the coals of the Shivee-Ovoo and Ulaan-Ovoo deposits were analyzed by proximate, ultimate, and FTIR spectroscopic analysis. It was confirmed that the Shivee-Ovoo coal is a low-rank lignite coal of B2 mark, and the Ulaan-Ovoo coal is subbituminous coal. So, they are suitable raw materials for obtaining humic acids. The yield of humic acids from the Shivee-Ovoo coal is 23.2 % and their solubility in water is 78.05 %. The yield of humic acids of the Ulaan-Ovoo coal is 14.5 % and the solubility in water is 23.20 %. The yield of humic acids and the water solubility of the Shivee-Ovoo coal are much higher than those of the Ulaan-Ovoo coal, because the coal of Shivee-Ovoo deposit is a highly oxidized brown coal, while the coal of the Ulaan-Ovoo deposit is a higher rank subbituminous coal. These results show that the humic acids of both kinds of coal have good penetration ability in soil and higher bioavailability for plants. The IR spectra of humic acids of both coals and their humic acids show that the organic matter of humic acids consists mainly of aliphatic and aromatic compounds with carboxylic (-COOH), carbonyl (>CO), hydroxyl (-OH) and etheric (-O-) groups, which are characteristic of highly oxidized organic matter. Humic acids of the Shivee-Ovoo coal exhibit a high biological activity in relation to Iren wheat seeds. The highest biological activity was detected for humic acid concentration of 0.005 %.

Seven samples of sapropelite coals from the deposits differing from each other in the catagenetic maturity of the organic matter were studied by means of solid-state ¹³C NMR spectroscopy. Analysis of the obtained analytical data showed that carbon in the organic mass of the samples is largely concentrated in aliphatic structures since the most intense signals in the ¹³C NMR spectrum fall on the region of 0-50 ppm, corresponding to the absorption of carbon of methyl and methylene groups, as well as tertiary and quaternary carbon atoms. The largest amount of aliphatic carbon was found in the sample, which is characterized by the highest values of the yield of volatiles and the H/C atomic ratio. It was found that with a decrease in the H/C atomic ratio in the samples, their degree of aromaticity increases against the background of a decrease in the proportion of aliphatic structures and carbon bonded to oxygen by a single bond.

Hybrid carbon materials based on carbon nanofibres and ceramic blocks made of Al₂O₃, ZrO₂, TiO₂, and aluminosilicate (AlSi) were prepared by means of catalytic chemical vapour deposition of methane over Ni⁰ particles supported on monolithic carriers. The initial ceramic carriers, catalysts and hybrid materials were studied by means of XRD, TEM, SEM, IR spectroscopy, thermal analysis and low-temperature nitrogen adsorption. By varying the reaction conditions and catalyst composition, samples with the carbon phase content from 1.7 to 12 mass % were obtained. It is established that the activity of catalysts depends on the chemical nature of the carrier and increases in the sequence TiO₂ < Al₂O₃ < AlSi < ZrO₂. The chemical composition and acid-base properties of the carrier surface determine the structure and morphology of the carbon phase. Carbon nanofibers modify the porous structure of ceramic materials, causing an increase in the specific surface area and mechanical strength of the resulting hybrids compared with the original ceramic carriers.

The paper presents the results of a study of the influence of the method of extraction processing of brown coal on the output of brown coal bitumen. It was shown that O-alkylating treatment allows increasing the yield of bitumoids, and the use of ultrasonic treatment during alkylation not only promotes further increase in the yield of bitumoids (up to 52.0 %) but also reduces the process duration from 6 to 0.5 h. Biologically active substances were identified in the composition of bitumen samples by means of gas chromatography - mass spectrometry.

An attempt is made to comprehend the essence of the measures taken by mankind in the framework of the struggle against the results of anthropogenic influence on the environment. The issues of using financial mechanisms for reducing the emissions of greenhouse gases to achieve the global goals of curbing climate warming have been investigated. Among financial instruments, in particular, the use of carbon tax is considered in the world practice and under Russian conditions. The importance of using market-based carbon pricing mechanisms as effective measures to control the total global carbon load is stressed. The leading role of the activities carried out by the EU countries in this direction is shown. In particular, the results of the experience of thirty years in Sweden in the application of the carbon tax were studied. The documents related to the strategic planning in Russia aimed at reducing the emissions of greenhouse gases were evaluated. The analysis of the main mechanisms providing for the measures to achieve the strategic goals of reducing the emissions of greenhouse gases into the environment was carried out. The necessity of using financial instruments in regulating the activities of economic entities to ensure the reduction of negative impacts in the long-term outlook is emphasized. Measures are presented to tighten the regulation of carbon dioxide emissions in the Russian Federation.