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No 3 (2025)
Articles
Microwave destruction of high moor peat: modeling and experimental studies in a quartz reactor
Abstract
The article presents the results of theoretical and experimental studies comparing the thermal degradation of high moor sphagnum peat in the process of pyrolysis (thermolysis) initiated by convenient thermal and microwave exposure. Based on modeling using the commercial software package CST Studio Suite, reactor designs have been developed that allow for a correct comparison of these processes under identical conditions. Comparative experiments conducted on the basis of reactors with various thermal sources have demonstrated the advantages of microwave pyrolysis, which allows for “instantaneous” and volumetric heating of the product and its deeper processing with high energy efficiency. The results of peat processing under different thermal effects and the yield of pyrolysis reaction products are discussed.
3–10
Carbonization of α2-fraction isolated from thermosolvolysis coal pitch, analysis of the structure of carbonizates
Abstract
The article presents the results of the study of the composition and thermal transformations of α2-fraction (quinoline-soluble, toluene-insoluble), isolated from the pitch product of thermal dissolution of coal in a binary mixture of technical solvents of coal and oil origin. Based on thermal analysis data, the dynamics of α2-fraction destruction with the release of volatile substances in the temperature range up to 1100°C was established. Carbonized products were obtained by carbonization of the α2-fraction. The features of the molecular composition and spatial structure of the starting materials and the obtained carbonizates depending on temperature were studied using chemical analysis, IR spectroscopy, CP/MAS13C NMR and X-ray diffraction. A consistent transformation of spatial structural components into packet turbostratic and graphite domains was established. It was shown that at an elevated temperature of 1100°C, extended forms of graphite domains are formed — precursors of needle coke.
11–21
Impact of drainage on the physicochemical parameters of the peat deposit and the chemical composition of peat in a raised boreal bog
Abstract
The paper presents the results of a study of physical, chemical, and physicochemical parameters of the peat deposit in a raised boreal bog areas in both natural and drained states. Data were obtained on the quantitative content of the main groups of components in the organic part of peat (bitumens, humic and fulvic acids, easily and difficultly hydrolyzable compounds, and non-hydrolyzable residue). It is shown that the intensification of oxidative processes due to drainage leads to a slight increase in the proportion of thermodynamically stable compounds — humic acids and bitumens, as well as the non-hydrolyzable residue in peat. It was found that the most significant differences in the parameters determined in the study are characteristic of the pairs of sites “natural-drained” and “natural-rewetted”, while the differences between the disturbed sites for most parameters are not significant, as confirmed by the results of the Mann–Whitney U-test.
22–30
Gas sensor based а composite of MoS2 and functionalized multi-walled carbon nanotubes
Abstract
A gas sensor based on MoS2 and functionalized multi-walled carbon nanotubes (MWCNTs) was obtained by drop casting. A coating was created in which the sensitive material consisted of functionalized MWCNTs (treated in a mixture of H2SO4/HNO3, 3 : 1 vol %), coated with MoS2 nanoplatelets. Sensor tests were carried out in dynamic mode with respect to two different types of gases (NO2 and NH3). The sensor demonstrated high relative sensitivity (|ΔR/R0|=36%) for 10 ppm NO2 at room temperature (25 ± 1°C). When determining ammonia, the response of the gas sensor (at 25 ± 1°C) was significantly lower compared to nitrogen dioxide detection and varied in the range of 5–12.5% at 50–400 ppm. It was shown that functionalized MWCNTs acted as a conductive additive, which allowed for a high response of the sensor based on the MoS2/f-MWCNT composite already at room temperature.
31–37
Thermodynamic characteristic of nanocarbon adsorbents from the high-moor peat of the European North of Russia
Abstract
By thermochemical activation with NaOH from the high-moor peat of the European North Russia, activated nano-carbons were obtained with a pore surface area of 2335 m²/g and a total pore volume of 1.44 cm³/g, with predominance of micropores. One of the designs of the adsorption-thermodynamic approach in the evaluation of thermodynamic functions was considered. Based on the experimental data of adsorption of standard marker-adsorbent – liquid nitrogen on active coals by means of isotherm equations of differential isosterial adsorption heat obtained from known adsorption model approximations (Langmuir, Brunauer–Emmett–Tellier, Aranovich), a non-traditional algorithm for calculating differential thermodynamic functions (enthalpy, entropy, free energy) on the single adsorption isotherm was proposed.
38–47
Kinetics of heat accumulation and gas release of self-igniting carbon dumps
Abstract
The analysis of gas and heat emission processes from coal and rock dumps is carried out. The possibility of reducing the emission of gaseous combustion products into the atmosphere by influencing the thermal regime inside the dump is assessed.
48–52