Polycyclic aromatic hydrocarbons (PAHs) are the predominant chemical compounds in coal tar (CT). Extensive published data indicate their carcinogenic effects both on humans, in industrial workers, and on animals. However, there is a trend toward using CT as a medication for skin diseases, dermatitis, and psoriasis. But how safe is the use of CT for humans? This review systematizes data on the carcinogenic effects of PAHs on humans, their concentrations in coal tar, and the degree of exposure to carcinogenic factors during skin disease therapy.
This paper presents the results of a study assessing the impact of drainage and subsequent rewetting processes on the accumulation and specific features of the vertical activity distribution of Cs-137, Am-241, Pb-210, U-234, and U-238 in the peat deposit of an ombrotrophic boreal bog (exemplified by the Ilas bog complex in the Arkhangelsk oblast). The data obtained indicated an extremely low level of radioactive contamination in the studied areas. It was demonstrated that hydromelioration of peat deposits led to changes in activity levels and redistribution of the test series of technogenic and natural radionuclides, which was expressed in the shift and localization of their concentration zone toward the peatland surface. It was established that the transformation of the hydrological regime of the deposits during the drainage of ombrotrophic bog areas enhanced the binding of radionuclides by peat sediments, including due to changes in physicochemical conditions.
A comprehensive study of the calorific characteristics of composite biofuels based on birch phloem has been conducted. The lower heating values of composites with varying compositions, including brown coal, oil-containing waste, and pine needles, were measured calorimetrically. Linear relationships between the calorific characteristics and the composition of the composite (e.g., bast content) were identified. Verification calculations of the combustion heat of composites with a component ratio of 1 : 1 were performed using empirical formulas by Dulong, Mendeleev, Wondraczek, Nivel, and Given, followed by conversion to lower heating values based on experimentally measured moisture and ash content. The results indicated that the smallest deviations between calculated values and experimental data for combustion heat could be achieved using Dulong’s formula.
Air purification from volatile organic compounds (VOCs) remains a serious problem of maintaining public health and environmental safety due to their toxic properties and widespread use in various fields of industrial production. In the presented work, the kinetic patterns of acetone vapor adsorption processes with commercially activated carbon AG-3 and its nitric acid–modified analogues were studied. To obtain modified adsorbent samples, the initial activated carbon AG-3 was treated with 2 M, 4 M, and 6 M aqueous solutions of nitric acid at a temperature of 100°C for 2 h. The reaction mixture was then cooled to room temperature and washed with distilled water until the neutral pH of the filtrate was reached. The obtained samples were dried at 110°C until a constant mass was obtained. To evaluate the acidic properties of the surface of semiconductor adsorbents, the adsorption of pyridine from its solutions in octane was studied using UV spectrometry. The results showed that the sorbent samples obtained by treatment of the initial industrial activated carbon AG-3 with a 2 M aqueous solution of nitric acid had the highest acidity. A further increase in the concentration of nitric acid led to a decrease in the acidic properties of the adsorbent and the specific surface area of the modified samples. The processes of acetone vapor adsorption were studied at room temperature and atmospheric pressure using the gravimetric method. The kinetic data obtained was analyzed using the Yelovich and Morris–Weber pseudo-first and pseudo-second order models. It was found that acid modification of the adsorbent significantly increased its capacitance characteristics, but it had little effect on the rate of acetone vapor adsorption. At the same time, the activated carbon image modified with a 2 M HNO3 solution also showed the best results. Kinetic investigation has shown that, in all cases, the process of acetone vapor absorption under consideration was best described by a pseudo-second-order model, which indicated the limiting nature of the stage of chemisorption of adsorbate molecules on the adsorbent surface. At the same time, the use of the Morris–Weber model also showed a good agreement between experimental and calculated results, which indicated the possible influence of diffusion processes on the rate of acetone vapor adsorption as the number of free centers on the adsorbent surface decreased. The results obtained indicate that it is impossible to control the conditions of acid modification of carbon adsorbents in order to increase the effectiveness of their practical application.
The article considers the effect of exposure time and nominal value of PAN fiber on its structural properties during thermal stabilization. Three optimal modes were selected for each fiber rating, which can significantly increase the uniformity and completeness of stabilization, ensure a minimum concentration of residual nitrogen, and form a fiber structure that meets the requirements for a precursor to produce high-quality carbon fiber.
In order to study the effect of stress and temperature on the spontaneous combustion behavior of deep coal, important conclusions are drawn through relevant experiments and analysis. It is found that stress can inhibit the ability of coal surface to adsorb oxygen, because it causes the pore structure of coal sample to compress, and the available area for oxygen adsorption is limited. Under the same temperature condition, the CO, CO2 emission and heat discharge increase with the increase of stress. When the stress is the same, the temperature increase also makes the CO, CO2 emission and heat discharge show the same change trend. The relationship between stress, temperature and heat release is polynomial, and the maximum heat release intensity appears at 120°C and 6 MPa stress. Further analysis shows that the weights of coal ash, moisture, fixed carbon, volatile matter, external stress, temperature and coal heat release are 0.1291, 0.1183, 0.3550, 0.1537, 0.2437, and 0.4419, respectively. The main factor affecting coal sample heat release is its own fixed carbon content. The influence of temperature on heat release from coal sample is greater than that of stress. These research results provide an important reference for further understanding of the oxidation characteristics of deep mining coal and related influencing factors.
The growing demand for sustainable materials drives innovative approaches to convert waste into valuable products. This study investigates four recycled precursors – rice husk, pistachio shell, anthracite, and waste styrene-butadiene rubber (SBR) – for producing activated carbon with potential environmental and industrial applications. Each precursor varies in origin and composition, representing biogenic-siliceous, lignocellulosic, mineral, and polymeric waste types, respectively. Using comprehensive physicochemical characterization, including SEM and XRD analyses, the structural features and pore architectures of activated carbons derived from these precursors were examined. Rice husk exhibited a well-connected microporous network aided by its inherent silica content; pistachio shell showed mesoporosity with less ordered structure, while anthracite presented a dense microporous graphitic matrix. Carbon from waste SBR featured spherical particles with mesoporous character and sulfur functionalities beneficial for volatile organic compound adsorption. The study highlights how precursor composition influences pore development, surface chemistry, and thermal stability – key factors determining activated carbon performance. Moreover, this work emphasizes sustainability by promoting circular economy principles, turning diverse waste streams into high-value carbon materials with potential roles in pollution control, catalysis, and composite applications. This integrated structure–function–sustainability assessment provides valuable guidance for selecting suitable waste precursors tailored to specific activated carbon uses.
This study investigates the copyrolysis of waste paint oil (WPO) and algae biomass as an integrated waste-to-energy pathway for producing high-energy biochar while mitigating the environmental risks associated with WPO disposal. Copyrolysis experiments were conducted in a laboratory-scale fixed-bed reactor using WPO–algae weight ratios of 1 : 0.5 to 1 : 1.5 under an inert nitrogen atmosphere (150 mL/min), with temperatures ranging from 400 to 600°C, a heating rate of 10°C/min, and a residence time of 60 min. The physicochemical properties of WPO (density 0.88–0.89 g/mL; kinematic viscosity 4.5–5.0 mm2/s) were controlled to ensure feedstock consistency. The resulting biochars exhibited markedly improved solid-fuel characteristics compared to single-feed pyrolysis. Fixed carbon content increased from 65.3 to 72.8 wt
To comprehensively understand the gas migration characteristics of ventilation systems during mine reverse ventilation periods, a high-precision three-dimensional dynamic simulation model was constructed using the TF1M3D simulation platform. The model’s reliability was validated through comparison with actual measurement data from Daxing Coal Mine. The study investigated the spatiotemporal distribution characteristics of gas concentration within the 3D ventilation net during asynchronous reverse ventilation periods of multiple air shafts, the relationship between fan downtime and gas parameters, and the influencing patterns of ventilation control on gas migration. Results indicate that simulation errors for multiple air shafts asynchronous reverse ventilation in mines are less than 5
The efficiency of adsorption of polar organic solvents by activated carbon is determined by the chemical and textural properties of its surface. Chemical modification of the surface of well-known industrial adsorbents is one of the ways to improve their technical characteristics. The surface of four industrial activated carbons (AG-3, KAU, BAU-A, and EcoSorb) was modified by treating them with a 2 M aqueous solution of nitric acid. The changes in the acidic properties of the adsorbent surface were quantified by UV spectroscopy using adsorption of pyridine from its solution in n-octane. The adsorption characteristics of the obtained materials were studied by the gravimetric method using the adsorption of acetonitrile vapor at a temperature of 25°C and atmospheric pressure as an example. The obtained results were compared with similar indicators for the initial unmodified activated carbons. The analysis showed that acid-modified adsorbents had higher rates of adsorption and equilibrium specific capacity for absorption of acetonitrile vapor than their original counterparts. The capacitance characteristics increased in the order mKAU < mBAU-A < mAG-3 < mEcoSorb, which mainly correlated with changes in the acidic surface properties of the modified carbon adsorbents. At the same time, the maximum increase in capacitance characteristics was shown by mEcoSorb and mKAU adsorbents, and the minimum increase was shown by mBAU-A. Kinetic modeling has shown that the process of acetonitrile vapor adsorption, as in the case of nonpolar volatile organic compounds (VOCs), was best described by a pseudo-second-order model. Therefore, due to specific interactions between adsorbate and adsorbent molecules, chemisorption was the rate-determining stage of the process under study. The results obtained emphasized the important role of surface functionalization of industrial activated carbons using chemical reagents to improve their adsorption characteristics.
The results of high-temperature hydrogenation of the phenolic fraction of coal tar from AO Shubarkol Komir, 2-propylphenol, and 2-tert-butyl-6-methylphenol, in the presence of molybdenum and chromium oxides on ZSM-5 zeolite (MoO3/ZSM, Cr2O3/ZSM) are presented. It was found that the hydrogenation of phenols with linear and branched alkyls under identical conditions differed in the process direction. For the MoO3–ZSM catalyst, dealkylation–reduction led to the formation of aromatic hydrocarbons, while for the Cr2O3–ZSM catalyst, dealkylation–reduction and disproportionation led to the formation of light phenols.
The article presents the results of a study on the production of drilling fluid components based on brown coal from the Kangalas deposit. It was demonstrated that mechanical activation of brown coal with the addition of 16–18
Humic acids are unevenly distributed throughout the Sergeyevsky coal deposit. This is due to the variety of sources of humic material and the different conditions under which coal accumulates. The upper coal seam contains a high concentration of allochthonous humic acids, which were formed under oxidative conditions from terrestrial biomaterial that was introduced into the area. Humic acids with autochthonous origins are present in coal in minimal concentrations, as they are derived from aquatic vegetation that grew in the area where the coal formed. An intermediate group of humic acids has a mixed origin and was formed under conditions with varying facies, where physical factors played a dominant role. The anaerobic environment of the lower part of the deposit promotes the development of processes that reduce the concentration of humic acids by dehydrating, decarboxylating, and demethylating them. The presented factual material on the geochemical aspects of humic acid accumulation is consistent with palynological data on the distribution of biologically predestined plants in the Sergeyevsky brown coal deposit.
In this study, a two-stage approach was employed to produce porous carbons from Manchurian walnut shells (MNS). The shells were utilized as a cost-effective biomass precursor for activated carbon production. The first step involved the carbonization of the shells, followed by activation using either carbon dioxide or potassium hydroxide. As a result, two series of biochar samples were prepared by varying the duration of CO2 activation and the KOH-to-precursor ratio. This approach enabled an investigation of the CO2 capture potential of the MNS-derived activated carbons. The structural evolution of the biochars was characterized using N2 physisorption, scanning and transmission electron microscopy. The results revealed that the original cellular structure was well-preserved after carbonization, while the activation step led to its significant transformation. Notably, the specific surface area, total pore volume, and micropore volume achieved after KOH activation were more than three times higher than those after CO2 activation. Nevertheless, CO2 activation is more economical and simpler than the chemical KOH method. The microporous structure of the samples changed with the KOH/carbonized MNS ratio. As the amount of KOH increased, all textural properties improved, except for the volume of narrow micropores (size <0.8 nm). The CO2 adsorption capacities of all samples were measured at 298 K and 1 bar. The maximum CO2 uptake in each series was 3.0 and 4.0 mmol/g, respectively. These values are competitive within the current state of CO2 adsorbent development.
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.
This review is devoted to nitrogen-doped carbon materials and strategies for their synthesis, which result in the formation of substances enriched with different forms of nitrogen: pyridine, pyrrole, quaternary (graphene-like), nitrile, amine, and oxidized nitrogen. It has been shown that the predominant presence of a certain form of nitrogen in the composition of N–carbon materials contributes to the manifestation of various properties that are important from a practical point of view, including electrophysical, adsorption, and other properties. The importance of targeted regulation of the nitrogen state in N–carbon materials is also noted. Based on the analysis of approaches to N-functionalization of carbon materials considered in the literature, a fundamental scheme for obtaining materials with a predominant presence of a target form of nitrogen is proposed.
The efficiency of microwave irradiation of a microporous sample of coconut shell activated carbon was assessed using physicochemical methods. After each adsorption–microwave irradiation cycle, the porous structure parameters of the adsorbent and adsorption characteristics relative to the original sample were determined. It was shown that the microwave irradiation method is not suitable for microporous samples of coconut shell activated carbons on adsorption of the herbicide 2,4-dichlorophenoxyacetic acid on them.
The effect of liquid-phase oxidation of porous carbon composite material (PCCM) with nitric acid on its structural and physicochemical characteristics has been investigated. As shown by low-temperature nitrogen adsorption, the oxidation of PCCM with 50 wt.
Today, the coal mining industry is continuously developing in many countries. However, industrial safety standards are not always observed when working in underground mines. Unfortunately, the results of the literature review indicate high risks in coal mining enterprises. The human factor is the main cause of occupational injuries. At the same time, the high concentration of hazardous chemical compounds in coal dust triggers a wide range of occupational respiratory diseases in workers. This brief review aims to identify the causes of accidents at enterprises and examine current innovative technologies for preventing hazardous situations. It is shown that digital transformation technologies are currently most actively used in coal mining companies.
