Search Results (102)

The growing global demand for energy necessitates the efficient utilization of unconventional petroleum resources, particularly heavy oil reserves. However, extracting, transporting, and processing these resources remain challenging due to their low mobility, low API gravity, and significant concentrations of resins, asphaltenes, heteroatoms, and metals. In recent years, various in situ upgrading techniques have been explored to enhance heavy oil quality, with catalytic aquathermolysis emerging as a promising approach. The effectiveness of this process largely depends on the development of cost-effective, environmentally friendly catalysts. This study investigates the upgrading performance of water-soluble ammonium alum, (NH₄)Al(SO₄)₂·12H₂O, for an extra-heavy oil sample from the Zarafshan Depression, located along the Tajikistan–Uzbekistan border. Comprehensive analyses demonstrate that the catalyst facilitates the breakdown of heavy oil components, particularly resins and asphaltenes, into lighter fractions. As a result, oil viscosity was significantly reduced by 94%, while sulfur content decreased from 896 ppm to 312 ppm. Furthermore, thermogravimetric (TG-DTG) analysis, coupled with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), revealed that the thermal decomposition of ammonium alum produces catalytically active Al₂O₃ nanoparticles. These findings suggest that ammonium alum is a highly effective water-soluble pre-catalyst for hydrothermal upgrading, offering a viable and sustainable solution for the development of extra-heavy oil fields. Full article

This study investigates the chemical stability and leaching behavior of two environmentally sustainable EPDM elastomers filled with circular carbon black (CCB) and recycled carbon black (RCB) when exposed to acidic, fuel cell-like environments. Accelerated aging tests were conducted in sulfuric acid solutions of varying concentrations (1 M, 0.1 M, and 0.001 M) at 90 °C for 1000 h to simulate long-term degradation in proton exchange membrane fuel cell (PEMFC) sealing applications. Complementary hot water extraction tests (HWET) were performed at 80 °C for up to 168 h to evaluate ionic leaching via conductivity measurements. HPLC-DAD analysis was used to assess organic leachates, while surface changes were examined by SEM and thermal transitions by DSC. Results revealed lower leaching and improved surface preservation in the CCB-filled EPDM, which remained below the critical 5 µS/cm ionic conductivity threshold for longer durations than its RCB counterpart. HPLC results showed filler-dependent trends in organic compound release, with CCB EPDM exhibiting higher leaching only under strong acid exposure. SEM confirmed greater surface damage and porosity in RCB EPDM. Overall, both materials demonstrated adequate chemical resistance, but the CCB formulation exhibited superior long-term stability, supporting its use in sustainable PEMFC sealing applications. Full article

In rocketry today, conventional hypergolic propellant combinations typically use hydrazine-derived fuels and oxidizers based on nitrogen tetroxide. Due to their high toxicity and consequently expensive handling, safer alternatives, so-called “green hypergolics”, are currently being developed. The ionic liquid-based fuels [EMIM][SCN], HIP_11 and HIM_30, paired with highly concentrated hydrogen peroxide as an oxidizer, are three candidates for such green hypergolics, which are currently under research at the German Aerospace Center (DLR). These combinations have been shown to exhibit reliable hypergolic ignition. For a better understanding of the reaction process and to assess the risks in working with these propellants, it is desirable to determine their combustion products. A test setup was designed to extract the gaseous combustion products from hypergolic drop tests. The gas samples were analyzed using Fourier-transform infrared spectroscopy and the gaseous combustion products were determined from the infrared spectra. Additional tests with varied oxidizer concentration or alternative fuels were conducted to further investigate detailed aspects of the findings. It was concluded that [EMIM][SCN], HIP_11 and HIM_30 produce very similar sets of combustion products with hydrogen peroxide, including water vapor, carbon dioxide, carbon monoxide, hydrogen cyanide and sulfur dioxide. Finally, the combustion products were compared to the substances produced when thermally decomposing the fuels. This confirmed that the previously detected substances were caused by a reaction between hydrogen peroxide and the fuels, rather than by their thermal decomposition due to heating. Full article

This paper reports the latest update to and a 24 h continuous operation test of the CEU’s thermochemical iodine–sulfur cycle water-splitting system with a maximum H₂ hydrogen production capacity of 1500 L/h. To address challenges such as high energy consumption and severe corrosion in traditional processes, the system was updated and optimized by introducing a small-cycle design, simulated using Aspen Plus software, achieving a thermal efficiency of 53%. Specifically, the key equipment improvements included a three-stage H₂SO₄ decomposition reactor and an HI decomposition reactor with heat recovery, resolving issues of severe corrosion when H₂SO₄ boils and reducing heat loss. During 24 h continuous operation in January 2025, the system achieved a peak hydrogen production rate of 1536 L/h and a long-term stable rate of approximately 300 L/h, with hydrogen purity reaching up to 98.75%. This study validates the potential for the scaling up of iodine–sulfur cycle hydrogen production technology, providing engineering insights for efficient and clean hydrogen energy production. Full article

Traditional tomato-braised beef brisket with potatoes is celebrated for its rich, complex flavors and culinary appeal but requires lengthy preparation. Pre-packaged versions of the dish rely on thermal sterilization for safety; however, high-temperature processing accelerates protein and lipid oxidation, thereby compromising its sensory quality. As the demand for ready-to-eat meals grows, the food industry faces the challenge of ensuring microbial safety while preserving flavor integrity. In this study, low-temperature plasma sterilization (LTPS) (160 KV, 450 s) was evaluated as a non-thermal alternative to conventional high-temperature short-time (HSS) sterilization. Furthermore, a comprehensive analysis was conducted over a 10-day storage period, assessing microbial viability, physicochemical properties (pH, shear force, and water-holding capacity), oxidative markers (TBARS, TVB-N, and protein carbonyls), volatile compounds (GC-MS), and electronic nose (e-nose) responses. The results revealed that LTPS (160 kV, 450 s) successfully maintained bacterial counts below regulatory limits (5 lg CFU/g) for 72 h, ensuring that the microbial indicators of short-term processed products sold to supermarkets through cold chain logistics were in the safety range. Additionally, LTPS-treated samples showed a 4.2% higher water-holding capacity (p < 0.05) during storage, indicating improved preservation of texture. Furthermore, LTPS-treated samples exhibited 32% lower lipid oxidation (p < 0.05) and retained 18% higher sulfhydryl content (p < 0.05) compared to HSS, indicating reduced protein oxidation. GC-MS and e-nose analyses showed that LTPS preserved aldehydes and ketones associated with meaty aromas, while HSS contributed to sulfur-like off-flavors. Principal component analysis showed that the LTPS samples had shorter distances across various storage periods compared to HSS, indicating reduced differences in aroma difference. The findings of this study demonstrate LTPS’s dual efficacy in microbial control and aroma preservation. The technology presents a viable strategy for extending the shelf life of pre-prepared meat dishes while reducing oxidative and flavor deterioration, thereby establishing a solid foundation for LTPS application in the pre-prepared food sector. Full article

This research presents the impact of diesel blends with tire pyrolysis oil (TPO) as an additive for minimizing the wear and tear of engine components. This study investigates the blends of normative diesel oil with TPO content ranging from 5% m/m to 20% m/m. Reference measurements are made for pure diesel oil (D100) and pure TPO. This investigation included an evaluation of the corrosion effect and the effect of the fuels tested on abrasive wear. For each fuel, the sulfur content, water content, lubricity (which is defined as the corrected average diameter of the wear trace during the high-frequency reciprocating rig (HFRR) test), and impurity content are determined. Impurities are assessed using indicators such as ash residue, coking residue from 10% distillation residue, determination of wear metals and contaminants, insoluble impurity content, and total sediment by hot filtration. All parameters are determined using recognized methods described in international standards. Approximation models are built for all the analyzed parameters, which can be used in future studies. At the same time, the individual values of the analyzed factors are compared with the threshold values specified in selected standards and regulations. Consequently, it is possible to assess the usefulness of individual fuels in terms of meeting the requirements for minimum wear of engine components. The results show the suitability of pyrolysis oil and the potential for its use as an additive to fossil fuels in terms of meeting most factors. Some of the fuels tested did not meet the standards for acceptable sulfur content. However, in terms of sulfur content, all of the analyzed fuels can be used to power watercraft and land-based power and thermal power plants equipped with flue gas desulphurization systems. A second indicator for not meeting the standards is the ash residue value, which indicates the high content of non-combustible, mainly metallic, substances in the pyrolysis oil used for the tests. Post-recycled oils must, therefore, undergo appropriate purification before being used as an additive to diesel fuels for internal combustion engines. Once the post-recycling oil has been subjected to desulfurization and advanced filtration, it can be used as a fuel additive for land vehicles, which fits in with closed-loop economies and sustainable development strategies. Full article

Although there are various boron production methods for modified activated carbons used in sulfur removal, catalyst synthesis, and hydrogen capture/storage processes, the modification of activated carbon with borax solutions has attracted attention as the easiest synthesis method. However, structural characterization analyses in previous studies contradict each other and, therefore, more detailed characterization is needed. In this study, 0.25 M and 0.5 M borax solutions are prepared in distilled water; then, 2 g of commercial activated carbon is added to each one, mixed at 60 °C, filtered, and dried. Thus, two different boron-modified activated carbon materials are obtained. Structural characterization tests of these materials are performed and analyzed by comparing with the literature. As a result, two different boron-modified activated carbon structural analyzes are compared and it is confirmed that commercially activated carbon material induced phase composition and chemical bond modification as a result of modification with borax. It is revealed that the induction of phase composition and chemical bond modification is more dominant with increasing borax concentration. The produced boron-modified activated carbon materials have great promise for the development of new technologies in the fields of the environment, energy, lightweight compressible materials, thermal insulation, and composite materials. Full article

A consistent life cycle assessment (LCA) methodology was employed to show how the type of alkali (NaOH or Na₂CO₃) used for extracting water glass from rice husks, as well as the type of acid (HCl, H₂SO₄, or HNO₃) used for precipitating water glass to nanosilica, affects the environmental emissions of rice husk-derived nanosilica (RH nanosilica). Six nanosilica production scenarios were explicitly compared to determine the most environmentally friendly route. The LCA results show that under the same circumstances, the majority of the environmental emissions of sodium hydroxide (NaOH) are significantly better than those of sodium carbonate (Na₂CO₃), except for the MAETP and ODP indicators. Similarly, except for the MAETP indicator, the environmental emissions of hydrochloric acid (HCl) are generally superior to those of sulfuric acid (H₂SO₄) and nitric acid (HNO₃). NaOH and HCl were selected as preferable for the extraction of silica from rice husks and the precipitation of water glass, respectively. In addition, the preferred route underwent further in-depth optimization with the aim of achieving optimal environmental emissions for RH nanosilica. The effects of electricity, diesel, fertilizers, and pesticides on the life cycle emission factors of RH nanosilica were examined. The results demonstrate that replacing traditional coal power with cleaner alternatives, such as wind, hydropower, solar power (both photovoltaic and thermal), and biogas electricity, can result in a substantial decrease in the life cycle emission factors of nanosilica, with reductions varying between 20% and 60%. An effective method to reduce emissions associated with diesel, fertilizers, and pesticides is to adopt effective measures to decrease their consumption. These findings provide valuable theoretical foundations and insights for the industrial application of RH nanosilica. These results have great significance for guiding and promoting the industrialization process of nanosilica derived from rice husks and accelerating its commercialization. Full article

Currently, the key challenge of the oil-refining industry worldwide is to produce environmentally friendly fuel in large volumes to meet market demand, which is due to strict environmental standards governing the permissible sulfur content in fuel. Natural gas, refinery gas, and coal gas contain acid gases such as hydrogen sulfide and carbon dioxide. These compounds must be removed from the gas stream because of the toxicity of H₂S and to prevent the acid gas-induced corrosion of pipelines and facilities. Hydrogen sulfide is released as a result of various industrial processes, and its removal is critical because this compound can cause corrosion and environmental damage even at low concentrations. Sulfur compounds are also present in natural gas, biofuels and other fuel gases used in power plants. This article proposes new adsorbents of natural and waste origin and presents the results of their testing for the removal of acid gases. This paper also considers methods for the preparation of adsorbents from waste and procedures for the removal of sulfur-containing compounds. Using agricultural, industrial waste to produce activated sorbents not only solves the problem of waste disposal but also reduces the cost of desulfurization, contributing to the creation of sustainable and environmentally friendly technologies. The Review Section comprehensively summarizes current research on hydrogen sulfide removal in gas cleaning processes using agricultural and industrial waste as highly efficient adsorbents. In the Experimental Section, 10 composite materials based on natural raw materials and wastes, as well as 6 commercial adsorbents, were synthesized and tested under laboratory conditions. The choice of materials for the adsorbent production was based on the principles of environmental friendliness, availability, and cost-effectiveness. The developed materials based on modified sludge from water treatment plants of thermal power plants are effective sorbents for the purification of gas emissions from petrochemical enterprises. For industrial use, it is necessary to solve the problems of increasing the economic attractiveness of sorbents from waste, the ability of regeneration, the competitive adsorption of pollutants, the use of indicator sorbents, the optimization of operating conditions, and safe waste disposal. Full article

Polybenzoxazine (PBz) resins exhibit excellent mechanical, thermal, and adhesive properties, making them interesting candidates for coating applications. Moreover, thanks to the incorporation of exchangeable ester bonds within the PBz network, the coating presents healable properties that are catalyzed by the intrinsic presence of tertiary amine within the PBz backbone. Unfortunately, these tertiary amine functions are also responsible for the limited resistance of such systems to acid environments by protonation. To address this limitation, the protection of tertiary amines inherent to the PBz network was investigated in this study by incorporating an aromatic group close to the amine function to minimize its protonation via hindrance/mesomeric effects. More precisely, benzoxazine precursors based on monoethanolamine (mea) and aminophenylethyl alcohol (Apa) were synthesized and tested as protective coatings of aluminium alloy substrates (AA1050). The resins were characterized by NMR, FTIR, rheology, TGA, DSC, and DMA. PBz synthesized from Apa exhibits enhanced thermal stability, reduced swelling rates in both water and acid, and shortened relaxation times. After application via solvent casting on AA1050 substrates, the acid resistance of the coatings was evaluated. Electrochemical impedance spectroscopy results demonstrated better resistance of the Apa-based resins in 0.1 M sulfuric acid after one month of immersion. Full article

In the present study, a green, scalable, and environmentally friendly approach was developed for the fabrication of Bi₂S₃-decorated CdS nanoparticles with an efficient hydrogen generation ability from the water. As a sulfur source, thiourea was used. The process was completed in two stages: mechanical activation and thermal annealing. The presence of spherical CdS nanoparticles and Bi₂S₃ nanorods in the CdS/Bi₂S₃ nanocomposite was confirmed and proved by XRD, Raman spectroscopy, SEM-EDS, and TEM. The synthesized CdS/Bi₂S₃ nanocomposites were evaluated for their photocatalytic hydrogen evolution capabilities. The CdS/Bi₂S₃ photocatalyst exhibited 25% higher photocatalytic activity compared to CdS, reaching a hydrogen evolution rate of 996.68 μmol h⁻¹g⁻¹ (AQE 0.87%) after 3.5 h under solar-light irradiation. Full article

Today, most of the world’s electric energy is generated by burning hydrocarbon fuels, which causes significant emissions of harmful substances into the atmosphere by thermal power plants. In world practice, flue gas cleaning systems for removing nitrogen oxides, sulfur, and ash are successfully used at power facilities but reducing carbon dioxide emissions at thermal power plants is still difficult for technical and economic reasons. Thus, the introduction of carbon dioxide capture systems at modern power plants is accompanied by a decrease in net efficiency by 8–12%, which determines the high relevance of developing methods for increasing the energy efficiency of modern environmentally friendly power units. This paper presents the results of the development and study of the process flow charts of binary and trinary combined-cycle gas turbines with minimal emissions of harmful substances into the atmosphere. This research revealed that the net efficiency rate of a binary CCGT with integrated post-combustion technology capture is 39.10%; for a binary CCGT with integrated pre-combustion technology capture it is 40.26%; a trinary CCGT with integrated post-combustion technology capture is 40.35%; and for a trinary combined-cycle gas turbine with integrated pre-combustion technology capture it is 41.62%. The highest efficiency of a trinary CCGT with integrated pre-combustion technology capture is due to a reduction in the energy costs for carbon dioxide capture by 5.67 MW—compared to combined-cycle plants with integrated post-combustion technology capture—as well as an increase in the efficiency of the steam–water circuit of the combined-cycle plant by 3.09% relative to binary cycles. Full article

Reducing mercury emissions to individual environmental compartments is now a global priority. However, undefined industrial sectors still pose a risk for mercury pollution, including the extraction, processing, and transport of crude oil and natural gas. Mercury contamination in hydrocarbon extraction areas can occur around blocking and bleeding systems, gas pressure reduction and metering points, gas purification devices, and reservoir water separators. The soil mercury content depends on the quality of the extracted fuel and can vary widely. This article reviews methods for remediating mercury-contaminated soils, including washing, acid washing, thermal desorption, removal and disposal, and soil stabilization to convert mercury into less harmful forms. The main objective of the work was to present the results of a pilot process of soil remediation contaminated with metallic mercury conducted in an industrial area. This paper presented laboratory and field test results evaluating the efficiency of a pilot soil remediation method at an industrial facility. Mercury contamination at the site was localized, primarily around blocking and bleeding systems, with soil mercury levels ranging from 1.6 mg/kg to 1116 mg/kg. In 80% of the samples, the mercury levels were 2–8.5 times above the acceptable industrial soil limits. Speciation studies indicated that over 50% of the samples contained mercury capable of emissions. The remediation method involved stabilizing the mercury in the soil by adding sulfur, forming stable mercury sulfide (cinnabar). The post-remediation measurements showed significant reductions in mercury emissions to the air, demonstrating the effectiveness of the mercury immobilization procedure. Full article

Lithium–sulfur batteries (LSBs) are widely studied as an alternative to lithium-ion batteries, this emphasis being due to their high theoretical energy density and low cost, and to the high natural abundance of sulfur. Lithium polysulfide shuttling and lithium dendrite growth have limited their commercialization. Porous polyvinylidene fluoride (PVDF) separators have shown improved performance (relative to hydrocarbon separators) in lithium-ion batteries due to faster lithium-ion migration and higher Li⁺ transference number. A thin polar PVDF membrane has now been fabricated via phase inversion (an immersion-precipitation method) yielding a β (polar) phase concentration of 72%. Preparation from commercial PVDF used dimethylformamide (DMF) solvent at the optimized crystallizing temperature of 70 °C, and pores in the membrane were generated by exchange of DMF with deionized water as non-solvent. The polar PVDF film produced has the advantages of being ultrathin (15 µm), lightweight (1.15 mg cm⁻²), of high porosity (75%) and high wettability (84%), and it shows enhanced thermal stability relative to polypropylene (PP). The porous, polar PVDF membrane was combined with a commercially available PP membrane to give a hybrid, two-layer, separator combination for LSBs. A synergy was created in the two-layer separator, providing high sulfur utilization and curbing polysulfide shuttling. The electrochemical performance with the hybrid separator (PP–β-PVDF) was evaluated in LSB cells and showed good cyclability and rate capability: those LSB cells showed a stable capacity of 750 mA h g⁻¹ after 100 cycles at 0.1 C, much higher than that for otherwise-identical cells using a commercial PP-only separator (480 mA h g⁻¹). Full article

In order to reduce the content of sulfur and ash in coal, improve the desulfurization and deashing rates, a combined experiment method of microwave magnetic separation-flotation was proposed for raw coal. The desulfurization and deashing rates of three experiment methods, namely, single magnetic separation, microwave magnetic separation, and microwave magnetic separation–flotation, were compared. Taking the microwave magnetic separation–flotation experiment method as the main line, the effects of the microwave irradiation time, microwave power, grinding time, magnetic field intensity, plate seam width, foaming agent dosage, collector dosage, and inhibitor dosage on desulfurization and deashing were discussed, and the mechanism of microwave irradiation on magnetic separation and flotation was revealed. The results show that under the conditions of a microwave irradiation time of 60 s, a microwave power of 80% of the rated power (800 W), a grinding time of 8 min, a plate seam width (the plate seam width of a magnetic separator sorting box) of 1 mm, a magnetic field intensity of 2.32 T, a foaming agent dosage of 90 g/t, a collector dosage of 2125 g/t, and an inhibitor dosage of 1500 g/t, the desulfurization and deashing effect is the best. The desulphurization rate is 76.51%, the sulfur removal rate of pyrite is 96.50%, and the deashing rate is 61.91%. Microwaves have the characteristic of selective heating, and the thermal conductivity of organic matter in coal is greater than that of mineral. Microwave irradiation can improve the reactivity of pyrite in coal, pyrolyze pyrite into high-magnetic pyrite, improve the magnetic properties, and improve the magnetic separation effect. Therefore, microwave irradiation plays a role in promoting magnetic separation. Through microwave irradiation, the positive and negative charges in coal molecules constantly vibrate and create friction under the action of an electric field force, and the thermal action generated by this vibration and friction process affects the structural changes in oxygen-containing functional groups in coal. With the increase in the irradiation time and power, the hydrophilic functional groups of –OH and –COOH decrease and the hydrophilicity decreases. Microwave heating evaporates the water in the pores of coal samples and weakens surface hydration. At the same time, microwave irradiation destroys the structure of coal and impurity minerals, produces cracks at the junction, increases the surface area of coal to a certain extent, enhances the hydrophobicity, and then improves the effect of flotation desulfurization and deashing. Therefore, after the microwave irradiation of raw coal, the magnetic separation effect is enhanced, and the flotation desulfurization effect is also enhanced. Full article