Himiâ tverdogo topliva

The influence of the gaseous medium during sample preparation, the granulometric composition, the duration of contact with air and the stage of metamorphism on the process of oxygen sorption from the air was established. It is shown that conducting sample preparation in an air atmosphere leads to primary oxidation of the outer surface of the coals, which introduces an error in determining the oxygen sorption rate constant. Fine coal fractions (0-0.2 mm) with a more developed outer surface have increased oxygen absorption activity. The rate of oxygen sorption is maximal at the initial moment of the interaction of active carbons with air and decreases with the duration of contact. The least metamorphosed hard coals of the D brand with a high content of reactive functional groups and a developed porous structure are characterized by the greatest chemisorption activity.

The study of active coals obtained from high-moor peat of the European North of Russia was conducted by method of thermochemical activation with NaOH with various types of pre-treatment (debituminization and pre-hydrolysis). Based on the results of the low-temperature adsorption of nitrogen, the derived active coals belong to the adsorbents in which the structure of the micro-agents predominates. The specific surface of the coal pores reaches 2330 m²/g, the total volume of pores – 1.44 cm³/g. It has been determined that the introduction of the pre-hydrolysis stage makes it possible to increase significantly the yield of active coals. For initial peat samples, the growth is 28%; for debituminized – 97%, moreover it significantly improve its sorption characteristics. It has been shown that weakly decomposed peat of the European North of Russia can be used as raw material for producing high-efficiency carbon microporous adsorbents.

The results of experimental studies of the influence of the initial moisture content of cedar needles on the time characteristics of ignition of coal-water suspensions based on D-grade thermal coal are presented. Biomass (fallen and freshly cut cedar needles) was used as an additive accelerating the ignition process. An analysis was carried out of the influence of the initial moisture content of the plant additive in the composition of water-soluble suspensions on the ignition delay times. It has been established that the initial moisture content of cedar needles does not have a significant effect on the time characteristics of the fuel ignition process (the difference does not exceed 4%), but the addition of needles leads to a significant reduction in the ignition delay times (the VUS ignites faster on average by 15%).

The work presents for the first time the results of obtaining titanium carbide using a vacuum-free electric arc method using various types of biocarbon obtained by classical pyrolysis of biomass waste, such as tangerine peel, pomelo peel, banana peel, pine nut shells, walnut shells. Analysis of X-ray diffraction patterns of the synthesized materials showed the repeatability of the experiment with the receipt of diffraction maxima indicating the formation of a cubic structure of titanium carbide. An analysis of the thermal oxidation of the resulting powders showed that up to a thousand degrees the process proceeds quite slowly, but with increasing temperature the oxidation rate increases significantly. It has been established that during thermal heating in an oxidizing environment, the mass of the studied titanium carbide powders obtained using various types of carbon increases, which is confirmed by thermogravimetric analysis.

Recent advances in modern chemistry provide environmental scientists with the ability to identify and track spilled oil residues in various environments. The compounds commonly used to identify the source of spilled oil are called biomarkers, they are universal in crude oil and petroleum products and are generally more stable to atmospheric environmental influences than most other oil constituents. The distribution of biomarker compounds is unique to each oil. Fingerprint indices calculated from oil fingerprints provide a stable and useful tool for determining the correspondence or non-correspondence of various oil residues present in some environmental samples. This paper highlights the main biomarkers of oil, their role in the study of oil and its deposits, and also shows the results of the authors’ own research.

An analysis of the correlations between the ash content of coal (A^d_ср) and the content of ash-forming elements was carried out. Significant positive pairwise correlations were revealed in the accumulations of SiO₂, Al2O₃, TiO₂ and each of them with ash content A^d_ср (r^cr_0.05=0.23). In the group Fe₂O₃, MgO, CaO, a significant positive correlation is observed between the accumulations of only Fe₂O₃ and MgO, but each of them correlates negatively with A^d_ср. A qualitative analysis of the distributions of petrochemical modules (GM, AM, ZhM, TM) of coal ash from the 2.2-Ulug seam of the Mezhegey deposit was carried out. Hydrolyzate destruction of the mineral matter of coal in 94% of the studied sample (n = 70) is represented by superhydrolysates (GM_min 2.07, GM_max 7.45), normohydrolysates (GM_min 0.86, GM_max 1.95), hypohydrolysates (GM_min 0.56, GM_max 0.84). A combined analysis of correlations between the ash content of coal (A^d_ср) and the contents of ash-forming elements and petrochemical modules of ash made it possible to establish the origin of ash-forming elements - ash-carrier Fe is aquagenic, ash-carriers Al, Ti are allotigenic.