Search Results (512)

An inevitable decrease in oil production from reservoirs all over the world necessitates the application of microbial enhancement of oil recovery (MEOR) technologies. The high total salinity of formation water is a factor strongly suppressing the growth of most industry-applicable strains of hydrocarbon-oxidizing bacteria. The halotolerant strain Ectopseudomonas guguanensis G3 isolated from an oil reservoir (Republic of Kazakhstan) has demonstrated high efficiency of oil degradation and presumable biosurfactant production. The ability of the strain to utilize crude oil, n-alkanes, toluene, and xylene and its resistance to NaCl concentrations up to 6% were shown, as well as a high decrease in the interfacial tension of the culture liquid. Genomic analysis of the strain confirmed its ability to oxidize aromatic oil compounds and a wide range of n-alkanes (with a chain length up to C₃₀) and revealed its potential capabilities to produce alginate, consume nitrate and urea as nitrogen sources, and synthesize betaine as an osmoprotectant. These findings demonstrate the high potential of E. guguanensis strain G3 to be used in oil reservoirs with high-salinity formation water in the biotechnology of oil displacement through oil degradation and in situ microbial metabolite production. Full article

Syzygium polyanthum (Wight) Walp., commonly known as Indonesian bay leaf or Daun salam, is widely used as a culinary and traditional botanical resource. However, region-specific information on its lipophilic constituents remains limited, and the sustainability implications of solvent-dependent phytochemical profiling are rarely addressed. This study characterized the GC–MS-detectable volatile lipophilic constituents of a selected nonpolar fraction of S. polyanthum leaves collected from Paniki Bawah, Mapanget District, Manado, Indonesia, using GC–MS, while evaluating solvent-related limitations for future greener extraction strategies. Dried leaf powder was macerated with 96% ethanol, followed by liquid–liquid partitioning with n-hexane and ethyl acetate. The n-hexane fraction was separated by silica gel column chromatography, and a TLC-selected fraction was analyzed by GC–MS. Compound annotation was supported by NIST 17 library matching, retention-index comparison using a C8–C40 n-alkane series, diagnostic ion evaluation, solvent blank analysis, and triplicate injections. Ethanolic extraction of 900 g dried powder yielded 87.0 g crude extract (9.67%). The n-hexane, ethyl acetate, and aqueous fractions yielded 5.98%, 21.15%, and 72.87%, respectively. GC–MS analysis tentatively annotated 11 compounds representing 94.44% of the total normalized peak area. The major constituents were palmitic acid, phytol, squalene, and neophytadiene. All annotations showed match scores of 90–98%, ΔRI values of 4–8 units, and RSD values of 1.86–3.27%. Although ethanol use, sunlight drying, solvent recovery, and recirculating chiller-assisted evaporation partially aligned with green chemistry principles, the use of n-hexane and chloroform means that the workflow should not be described as fully green. This study provides a baseline GC–MS fingerprint to support future greener extraction optimization. Full article

Gasoline evaporation is a significant source of urban volatile organic compounds (VOCs). In this study, we selected Nanjing, a major city in the Yangtze River Delta of China, and developed a high-resolution (1 km × 1 km) gridded VOC species emission inventory for gas stations based on measured VOC emission characteristics and statistical data on gasoline and diesel sales. The results show that VOC emissions from gas stations were correlated with population density and road networks, and were mainly concentrated in the downtown area. The emitted VOCs were dominated by alkanes (58%) and oxygenated VOCs (19%), with i-pentane, n-butane, and methyl tert-butyl ether (MTBE) as the major components. C4–C5 alkenes were identified as the key contributors to ozone (O₃) formation, while aromatics contributed most to secondary organic aerosol (SOA) formation. Health risk assessment indicates that, for gas station workers, both carcinogenic and non-carcinogenic risks associated with gasoline and diesel VOC evaporation exceed acceptable thresholds. Benzene, 1,2-dichloroethane, and 1,2-dibromoethane posed the highest carcinogenic risks, whereas acrolein, benzene, and 1,3-butadiene contributed most to non-carcinogenic risks. For urban residents, the health risks from gas station VOC emissions were generally within acceptable levels; however, under unfavorable meteorological conditions, residents living near gas stations may still face elevated health risks. This study highlights the significant impacts of gas station-related VOC emissions on air quality and human health, and informs targeted control and mitigation strategies for gasoline evaporation. Full article

Hakea sericea is one of the most aggressive invasive shrubs in Mediterranean ecosystems, producing large quantities of lignocellulosic residues during control operations. This study evaluates thermochemical liquefaction as a valorisation route for this biomass, linking biomass conversion with invasive species management. Whole-plant material was liquefied through acid-catalysed reactions using 2-ethylhexanol as the solvent and p-toluenesulfonic acid as the catalyst. A response surface methodology design was used to assess the effects of temperature, reaction time, and catalyst loading on conversion efficiency. The biomass contained 35.92% cellulose, 32.29% hemicellulose, and 17.36% lignin. Liquefaction yields ranged from 15.59% at 120 °C for 30 min to 82.7% at 160 °C for 90 min, with conversions above 70% achieved within 30 min at higher catalyst concentrations. The regression model explained 87.5% of the variability in liquefaction performance. Spectroscopic and thermal analyses confirmed extensive depolymerisation of lignocellulosic polymers and the formation of an aliphatic-rich bio-oil, with 57.5% of proton signals located in the alkane region of the ¹H NMR spectrum. The bio-oil exhibited a higher heating value of 31.91 MJ kg⁻¹, corresponding to an energy recovery of about 85%. Microscopic observations showed strong structural disruption of plant fibres. Overall, the results demonstrate efficient conversion of H. sericea biomass into energy-dense liquid products, supporting its use in invasive species control strategies. Full article

Marine incursions can profoundly alter biological input and environmental conditions in transitional sedimentary basins, yet their ecological effects remain insufficiently understood in the northern Central Myanmar Basin (CMB). Here, we investigate Upper Cretaceous to Eocene mudrocks from the northern CMB using integrated organic biomarker and elemental geochemical analyses to reconstruct biological precursors, depositional environments, and ecosystem responses during seawater incursions. The biomarker assemblages, including n-alkanes, isoprenoids, tricyclic terpanes, and C₂₇–C₂₉ regular steranes, indicate persistent mixed inputs of marine algal organic matter and terrestrial higher-plant debris. In particular, the upward increase in C₂₉ steranes from the Upper Cretaceous to the Eocene suggests a progressive strengthening of terrestrial input through time. Elemental proxies, including Sr/Ba, Th/U, Y/Ho, (Zn + Ni)/(Ga × 5), Sr/Cu, Rb/Sr, and V/(V + Ni), indicate that deposition occurred under marine-influenced, brackish to locally saline, warm–humid, and predominantly weakly reducing to reducing conditions. We interpret these patterns as evidence that marine incursions reorganized habitat conditions and biological input in a near-equatorial transitional ecosystem. The increasing contribution of terrestrial biomass was likely linked to the progressive uplift and exhumation of the Indo-Burman Ranges, which expanded exposed land area and enhanced the supply of land-derived organic matter to the basin. These results provide a biomarker-based perspective on how marine incursions and paleogeographic reorganization jointly shaped ecosystem dynamics and organic-matter preservation in the northern CMB. Full article

The antifoaming performance of natural gas desulfurization solvents is critical for maintaining product gas quality and ensuring the safe operation of processing units. Hydrocarbon impurities can enter amine solutions through feed-gas entrainment, wellhead flowback carryover, and leakage of equipment lubricants. These contaminants may gradually accumulate in the solvent system and become a significant contributor to foaming. To address the industrial demand for rapid quantitative determination of hydrocarbon contaminants in desulfurization solvents, this study investigates in-service UDS-series solvents and representative samples collected from a natural gas purification plant in western Sichuan. NMR spectroscopy and GC-MS analyses reveal that the impurities are predominantly n-alkanes in the C₁₃-C₁₈ range, based on which a corresponding reference standard oil was prepared. COSMO-RS calculations combined with molecular interaction analysis identify n-hexane as the optimal extraction solvent. The ultraviolet spectrophotometric method commonly used to determine hydrocarbons in environmental water samples shows limited sensitivity to long-chain n-alkanes and requires strong acid pretreatment that disrupts the amine solvent matrix, rendering it unsuitable for UDS solvents. In contrast, the n-hexane extraction-GC-FID method showed good linearity, precision, and accuracy, meeting engineering analytical requirements for monitoring hydrocarbon contamination in MDEA-based UDS desulfurization solvents. Full article

This study aims to systematically investigate the combined effect of chemical activation of açaí seeds (Euterpe oleracea Mart.), with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, and process temperature by pyrolysis of alkaline activated açaí seeds on the yield of reaction products (bio-oil, gas, H₂O, and biochar), physicochemical properties (acid value, density, and kinematic viscosity) and chemical composition (hydrocarbons and oxygenates) of bio-oil. Catalytic pyrolysis was carried out in a 143 L reactor at temperatures of 350 °C, 400 °C, and 450 °C, 1.0 atmosphere, operating in batch mode. The NaOH activation played a crucial role in modifying the thermal degradation pathway of the biomass, promoting the formation of specific chemical structures and altering the product yields. NaOH acted as a catalyst, enhancing the deoxygenation of the biomass and stimulating the formation of hydrocarbons. As a result, the yields of bio-oil, water, biochar, and gas varied from 5.77 to 7.20% (by mass), 14.90 to 19.77% (by mass), 41 to 54% (by mass), and 25.33 to 32.03%, respectively, influenced by the increase in temperature. FT-IR analyses indicated the presence of characteristic chemical functions of hydrocarbons (alkanes, alkenes, and aromatics) and oxygenated compounds (phenols, cresols, ketones, esters, carboxylic acids, aldehydes, and furans), with an intensification of hydrocarbon signals at higher temperatures. GC-MS analysis identified hydrocarbons and oxygenated compounds as the main chemical classes in the bio-oil, showing a strong dependence on pyrolysis temperature. It was observed that hydrocarbon concentration in bio-oil increased from 49.7% to 57.88% (area) with increasing temperature, while the concentration of oxygenated compounds decreased from 13.88% to 6.69% (area), demonstrating that NaOH activation, combined with temperature elevation, favors the formation of hydrocarbons and the reduction of oxygenated compounds, thereby improving the quality of the produced bio-oil. Full article

The reagent regime is a key means to regulate mineral flotation behavior, with collectors being particularly crucial for enhancing the flotation process. This paper systematically investigates the action mechanisms of hydrocarbon oil components such as n-Nonane, n-Dodecane, n-Tridecane, n-Tetradecane, and n-Pentadecane in coal slime flotation through a combined approach of molecular dynamics simulation and experimental verification. The simulation results show that as the alkane chain length increases, the absolute value of the adsorption energy between the alkane and coal gradually increases (the adsorption energy is negative, indicating that the adsorption process can occur spontaneously), with n-Pentadecane exhibiting the highest adsorption energy. Experimentally, the oil–water mixture achieved optimal dispersity after ultrasonic treatment and standing for 10 min. This dispersity is characterized by the average oil droplet diameter and the most uniform droplet size distribution under the test conditions. The wetting heat test further verified that pentadecane exhibits the strongest interaction with coal slime and the fastest adsorption rate. In flotation tests, n-Tetradecane demonstrated the best actual flotation performance, with a clean coal yield of 70.88%, a combustible recovery of 82.55%, and a flotation perfection index of 50.75%. This study reveals the influence mechanism of alkane chain length on coal slime flotation behavior, providing a theoretical basis for the screening and compounding of efficient collectors. Full article

The addition of calcium oxide (CaO) as an additive to B35 biodiesel enhances molecular modifications through changes in the FAME chemical structure. CaO was dispersed in biodiesel using 48 kHz ultrasonic vibration for 48 hours, inducing an exothermic reaction that generated Ca⁺ and O⁻ ions. These ions primarily affected C–H bonds in CH₃, CH₂, and CH groups, with the strongest impact on CH₃ due to its highest bond energy. This perturbation triggered molecular fragmentation and the formation of acetylenic and sp³ alkane C–H compounds, serving as precursors for new functional groups. The study revealed a potential energy increase of 8.1% for acetylenic C–H chains and 13.2% for sp³ alkane C–H stretching. Full article

Maize (Zea mays L.) is a vital global crop whose productivity is severely threatened by abiotic stresses. Epicuticular waxes provide a hydrophobic barrier that protects land plants from environmental stresses. However, the role of key wax biosynthetic enzymes, such as aldehyde decarbonylase CER1, in maize stress adaptation remains unclear. In this study, we performed a functional characterization of ZmCER1 in maize. Our results show that the overexpression of ZmCER1 in both Arabidopsis and maize substantially improved tolerance to these abiotic stresses. Under stress conditions, the transgenic plants displayed better growth performance, elevated activities of antioxidant enzymes, and reduced levels of oxidative damage markers. Additionally, the alkane content—especially that of C29 and C31—was significantly increased in the ZmCER1OE lines. Through a yeast two-hybrid screening (Y2H screening), we identified the peroxisomal membrane protein ZmPEX14 as an interacting partner of ZmCER1, and the interaction was further confirmed by luciferase complementation (LUC) and bimolecular fluorescence complementation (BiFC) assays. We propose a model wherein ZmCER1 enhances stress tolerance not only by reinforcing the cuticular wax barrier but also by potentially regulating reactive oxygen species (ROS) detoxification via association with ZmPEX14. Collectively, our findings establish ZmCER1 as a key regulator of abiotic stress tolerance in maize and a promising candidate for the molecular breeding of stress-resilient crops. Full article

The ethylene aromatization (ETA) reaction is a pivotal route for non-petroleum-based aromatics production, yet a systematic understanding of its thermodynamic constraints and kinetic modulation remains elusive. Herein, an integrated thermodynamic and kinetic study is presented to elucidate the temperature-dependent reaction pathways over metal oxide-modified HZSM-5 catalysts. Thermodynamic calculations reveal that while oligomerization, cyclization, and the hydrogen transfer (HT) pathway are exothermic, the aromatics-generating dehydrogenation (DH) pathway is endothermic. Crucially, despite the general thermodynamic penalty imposed by elevated temperatures on most elementary steps, the overall ethylene aromatization reaction retains a strong driving force, underscoring the dehydrogenation pathway as the thermodynamic and kinetic key to aromatic selectivity. Experimentally, it is demonstrated that modifying HZSM-5 with ZnO, Ga₂O₃, and ZnGa₂O₄ effectively tunes the Lewis-to-Brønsted acid (L/B) ratio. A strong linear correlation is established between the L/B ratio and the apparent activation energy, with a higher L/B ratio significantly lowering the activation barrier. This synergistic effect optimally promotes the dehydrogenation pathway, suppresses alkane by-product formation, and maximizes aromatic yield within an optimal temperature window of 470–520 °C. The findings provide a fundamental and practical framework for the rational design of high-efficiency ethylene aromatization catalysts and the optimization of process conditions via targeted acid site engineering. Full article

Direct-fired supercritical CO₂ cycles are considered a promising way to reduce CO₂ emissions in the energy sector. One of the key elements of such cycles is a combustor, in which natural gas is burned at supercritical pressures up to 300 atm in an O₂/CO₂ environment. Understanding the chemical combustion kinetics of C1–C4 alkanes, the main components of natural gas, in a supercritical CO₂-diluted medium is important for designing such combustors. This article provides an overview of studies on the chemical kinetics of C1–C4 alkanes combustion in CO₂ at ultra-high pressures. It has been established that with increasing pressure, regardless of the diluent, CH₃O₂ and HO₂ chemistries start to significantly influence the combustion of alkanes, but at the moment this influence is not sufficiently understood. Influence of CO₂ dilution on kinetics is mainly thermal, but the chemical effect is also significant. At the same time, the direct chemical effect of CO₂ is more important for the laminar burning velocity, while the indirect third-body effect is more important for the ignition delay time. However, the available literature lacks experimental measurements of the laminar burning velocity in a CO₂ environment at pressures above 70 atm, which limits the current understanding of chemical kinetics at supercritical pressures. Full article

Light hydrocarbons in shale oil readily volatilize during conventional coring, surface handling, storage, and laboratory preparation. The resulting evaporative loss causes systematic underestimation of Rock-Eval S₁ peak (free hydrocarbons measured by programmed pyrolysis), which can bias oil-bearing evaluation, sweet-spot delineation, and resource assessment. Here we investigate Chang 7₃ lacustrine shale oil in the Ordos Basin (China) using frozen cores recovered by pressure-retained coring from four wells. Time-series Rock-Eval pyrolysis and thermal desorption–gas chromatography (TD–GC) were used to quantify the magnitude, temporal evolution, and practical equilibrium time of light-hydrocarbon loss and to establish a practical restoration model. S₁ decreases with storage time and exhibits a clear two-stage behavior. Shale shows a rapid-loss stage during 0–90 days, followed by a practical equilibrium stage after 90 days (S₁ change less than 5%). Sandstone interbeds lose light hydrocarbons faster and more completely, reaching practical equilibrium after 60 days. TD–GC indicates that the lost fraction is dominated by n-alkane components lighter than C₁₃, with gaseous hydrocarbons showing the greatest depletion; medium and heavy fractions decrease modestly. Loss is coupled with progressive desorption from kerogen and clays, leading to enrichment of heavier components in the residual free hydrocarbons and a shift of the modal carbon number toward higher values. At the shale equilibrium time, total organic carbon (TOC) and vitrinite reflectance (R_o) jointly control the restoration factor K. We propose a two-parameter restoration model: K = (0.4024·ln (TOC) + 0.821)·(0.652·R_o + 0.4292). Applying the model to more than 50 conventionally cored wells reveals that the Qingyang–Zhengning area in the southwestern basin is the principal enrichment zone of original free hydrocarbons, followed by the Jiyuan area in the north and the Huachi area in the central basin, whereas the eastern basin is relatively depleted. The workflow provides a robust and transferable approach for correcting S₁ and improving shale-oil evaluation in lacustrine systems. Full article

The Qingshankou Formation shales in the southeastern uplift of the Songliao Basin provide an ideal archive for constraining the controls of paleoenvironment on organic matter enrichment. Taking the shale succession at the Niaohexiang section of Binxian as the study object, we combined field sampling with TOC measurements, whole-rock X-ray diffraction, and major, trace, and rare earth element analyses. The strata are dominated by black shale and dark gray mudstone, with mineral assemblages composed mainly of clay, felsic, and carbonate minerals; argillaceous shale exceeds 60%. Normal alkanes display a post-peak distribution with C₂₇ as the dominant peak, low Pr/Ph ratios, and gammacerane index values of 0.18–0.26. Regular steranes are generally V-shaped, whereas some samples show high C₂₉ sterane contents and a reversed L-shaped pattern. Major elements are dominated by SiO₂ and Al₂O₃, trace elements such as Sr and Ba are relatively enriched, and rare earth elements show light REE enrichment with a pronounced negative Eu anomaly. These signatures indicate an upper-crustal felsic provenance and a continental island arc tectonic setting. Organic matter contents are low and derived mainly from terrestrial higher plants with minor aquatic input. Paleoenvironmental reconstruction suggests deposition in a freshwater to slightly brackish, semi-arid, anoxic-reducing shallow lacustrine setting with relatively low productivity, whereas dolostone formed under more saline, arid, and more productive conditions. Climatic fluctuations, salinity variations, and alternating redox states jointly controlled organic matter enrichment, and late-stage lacustrine salinization and anoxia associated with dolostone horizons enhanced organic matter preservation. Full article

The development of modern society has intensified fossil fuel consumption, resulting in the depletion of oil resources and rising greenhouse gas emissions. In this context, the promotion of renewable alternatives in the transport sector has become essential, with Hydrotreated Vegetable Oil (HVO) emerging as a promising transitional fuel due to its compatibility with conventional diesel engines. To ensure proper engine operation and performance, the physical properties and chemical structure of HVO must be accurately characterized. Gas chromatography is commonly used for this purpose. While dedicated gas chromatography methods for HVO are available on specialized equipment, this study proposes a chromatographic method applicable to conventional gas chromatograph systems equipped with a flame ionization detector, enabling the analysis of HVO using commonly available laboratory equipment. The method was developed using commercially available HVO and pure n-alkanes (C₅–C₁₈) as reference compounds for component identification. The proposed approach enabled the estimation of carbon and hydrogen atom numbers in the analyzed fuel fractions and the determination of the stoichiometric air. The calculated values show good agreement with the literature data, confirming the reliability and applicability of the proposed boiling-point-based chromatographic method. Full article