Heavy Hydrocarbons Research Articles

Petrophysical Characterization and Gas Accumulation of Wufeng-Longmaxi Shale Reservoir in Eastern Margin of Sichuan Basin, SW China

Shale gas plays a significant role in meeting the increasing demand of energy resources, which enables the exploration and exploitation of gas from shale reservoir to be emphasized gradually. Aiming to serve a more responsible and efficient shale gas development, for example, to guide the hydraulic/nonaqueous fracturing operation, this work organized a comprehensive assessment on the petrophysical characterization and gas accumulation of the Upper Ordovician Wufeng-Lower Silurian Longmaxi shale reservoir (abbreviated as WL shale). Results indicate that the WL shale in Well-YC4 contains three third-order sequences (SS1-lower WL, SS2-middle WL, and SS3-upper WL), and each sequence contains a transgressive system tract (TST) and a high-stand system tract (HST), according to the logging information. Meanwhile, the SS1, SS2, and SS3 experienced variable sedimentary environment—with different relatively oxygenic and hydrodynamics. And the bottom section (SS1 and SS2) has a soft great brittle index (BI) value than the upper section (SS3), suggesting the bottom WL shale is better suited for hydraulic fracturing than the upper section. Besides, the organic matter indicates the WL shale has a decent hydrocarbon generation ability, and the thermal evolution degree is also conducive to the full generation of shale gas. The gas content of WL shale ranges in the scope of 0.76 m3/t~2.38 m3/t, in which CH4 is the primary composition and occupies 95.51%~99.36%, and the content of heavy hydrocarbon gases is limited. Besides, the drying coefficient indicates the dry gas is the dominate molecular composition in the gas content of WL shale. Hopefully, this work is instructive to a certain extent for the researchers and engineers who are working on WL shale gas in Sichuan basin.

Hydrogen Pressure as a Key Parameter to Control the Quality of the Naphtha Produced in the Hydrocracking of an HDPE/VGO Blend

The hydrocracking of high-density polyethylene (HDPE) blended with vacuum gas oil (VGO) has been studied to assess the effect of H2 pressure on the yield and composition of the products and with the aim of obtaining commercial fuels, mainly naphtha. The experiments have been performed using a PtPd/HY catalyst in a semibatch reactor under the following conditions: H2 pressure, 20–110 bar; 440 °C; catalyst to feed ratio, 0.1 gcat (gfeed)−1; HDPE to total feed ratio, 0.2 gHDPE (gfeed)−1; and reaction time, 2 h. The composition of the main fractions produced (gas, naphtha, and light cycle oil) reveals the interest in carrying out the process at 110 bar. Thus, conversions of 96 and 79% for the removal of heavy hydrocarbons and the removal of HDPE molecules have been obtained, respectively, together with a yield of naphtha of 53.4 wt%. This naphtha is mainly paraffinic, and it has a RON of 91.5 (within the commercial standards). Furthermore, three fractions have been observed in the analysis (temperature-programmed oxidation) of the coke. This analysis reveals that at 110 bar, the coke retained in the HY zeolite cages is less developed and burns at a moderate temperature.

Design of Constructed Wetland Treatment Measures for Highway Runoff in a Water Source Protection Area

Road runoff contains high levels of pollutants, such as heavy metals and hydrocarbons. If they are directly discharged into sensitive water bodies, they will cause irreversible pollution and damage to the water environment. Furthermore, the leakage of hazardous chemicals into sensitive waters will lead to serious consequences, so determining how to deal with road surface runoff has become an urgent problem. This research adopts a scheme for collecting and processing road runoff in a water source protection area using artificial wetlands. After optimizing and improving the general vertical flow of the wetland structure, a composite wetland structure and a relatively novel tandem wetland structure are proposed. An indoor model is established for experiments on various main wetland structure schemes. The results show that the two newly proposed wetland structures improve the possibility of water level control in general vertical flow structures. At the same time, the movement distance of the water flow in the wetland structure is changed to improve the treatment effect of runoff. The removal effect of composite and tandem wetland structures for heavy metals, petroleum substances, and COD (chemical oxygen demand) is significantly better than that of general vertical flow structures. Among them, the composite structure is better than the tandem structure at removing heavy metals, petroleum substances, and COD. However, due to the water discharge method of the structures, the latter has a better effect than the former in the treatment of suspended substances.

Reduction of Heavy Hydrocarbons from Oilfield Produced Water

This paper presents attempts to reduce the concentration of organic pollutants in oilfield produced wastewater before its discharge into natural water bodies or reinjection into the wells. The contaminant content was significantly decreased by wastewater treatment, based on solid phase adsorption, photocatalytic degradation of organic molecules and chemical oxidation of oily compounds. The study was conducted with real wastewater, which is in practice released in the environment. The produced water samples, taken from four sampling points in the oilfield site, were analyzed for physicochemical (temperature, redox potential (Eh), conductivity, pH, dissolved oxygen) and specific (chemical oxygen demand (COD), total oily hydrocarbons (TOH), phenols) parameters, cations (Ca2+, Mg2+, Na+, K+) and anions (Cl−, HCO3−, SO42−, S2−), in order to determine the initial water status. The organic contaminants in oilfield produced water showed COD of 39–58 mg/L, TOH of 152–363 mg/L and phenols of 0.07–0.21 mg/L. The TOH was chosen as a suitable parameter for the evaluation of the treatment method efficiency. The adsorption on activated charcoal decreased the TOH levels up to 52 mg/L, which corresponds to 85% removal of oily compounds. Chemical oxidation, carried out with Ca(ClO)2 in a concentration of 400 mg/L for 1 h at room temperature, showed TOH removal in the range of 80–94% for different wastewater samples. The use of 300 mg/L TiO2 or ZnO under UV irradiation for 12 h led to TOH removal of 25–78% and 82–92%, respectively. Both photocatalysts were characterized by using X-ray diffraction, reflectance UV-vis spectroscopy and scanning electron microscopy. The crystal forms anatase and wurtzite for TiO2 and ZnO, respectively, were found. The estimated band gap of 3.48 eV for direct transition in TiO2 and 3.25 eV for ZnO agrees well with that reported in the literature. Higher photodegradation of organic compounds was observed for ZnO, indicating that it absorbed more light photons than TiO2 did. A mechanism for photocatalytic degradation over a more efficient photocatalyst, ZnO, was proposed based on the GC-MS analysis of raw water and treated effluents produced for 6 and 12 h.

Estimating water content of natural gas mixtures considering heavy hydrocarbons contribution using artificial neural networks

The accurate estimation of the water content of natural gas is the basis for proper equipment design in natural gas processing and transmission facilities. Methods for estimating the water content of natural gas have been reported based on pressure and temperature data, and the concentration of acid gases. This work aims to develop a predictive model based on artificial neural networks (ANN) to estimate the water content of natural gas, considering the contribution of heavier hydrocarbons than methane, commonly present in the rich gases, gas condensates, or liquefied petroleum gases. The novelty of the proposed model is the incorporation of natural gas richness (GPM) as an input parameter for calculating the water content of natural gas, in addition to temperature, pressure, and acid gas equivalent content. Experimental data from the literature is used in the ANN training and validation, with the help of the BigML machine learning platform to perform a multi-layer-feedforward neural network. The ANN performance showed the ability to accurately predict the water content for different gas mixtures (rich, lean, sweet, and sour gases). Comparisons with available models in the literature are performed, showing that the ANN model provides accurate estimations (AAD: < 10%).

Combined Phenanthrene and Copper Pollution Imposed a Selective Pressure on the Rice Root-Associated Microbiome.

Combined organic and inorganic pollutants can greatly impact crops and microbes, but the interaction between coexisted pollutants and their effects on root-associated microbes under flooding conditions remains poorly understood. In this study, greenhouse experiments were conducted to investigate the individual and combined effects of phenanthrene (PHE) and copper (Cu) on rice uptake and root-associated microbial coping strategies. The results showed that more than 90% of phenanthrene was degraded, while the existence of Cu significantly reduced the dissipation of PHE in the rhizosphere, and the coexistence of phenanthrene and copper promoted their respective accumulation in plant roots. Copper played a dominant role in the interaction between these two chemicals. Microbes that can tolerate heavy metals and degrade PAHs, e.g., Herbaspirillum, Sphingobacteriales, and Saccharimonadales, were enriched in the contaminated soils. Additionally, microbes associated with redox processes reacted differently under polluted treatments. Fe reducers increased in Cu-treated soils, while sulfate reducers and methanogens were considerably inhibited under polluted treatments. In total, our results uncover the combined effect of heavy metals and polycyclic aromatic hydrocarbons on the assemblage of root-associated microbial communities in anaerobic environments and provide useful information for the selection of effective root-associated microbiomes to improve the resistance of common crops in contaminated sites.

Key Oil Content Parameter Correction of Shale Oil Resources: A Case Study of the Paleogene Funing Formation, Subei Basin, China

Estimating shale oil resources is critical in shale oil exploration, and the pyrolysis parameter S1 is a frequently used parameter to assess the oil amount in shale. However, S1 loses some light and heavy hydrocarbons due to core storage conditions and experimental technology, resulting in underestimating shale oil resources. In this paper, a set of models were developed to correct the light and heavy hydrocarbon losses for S1 based on conventional and multistage Rock-Eval experiments on liquefrozen and room-temperature shales collected from the Funing Formation, Subei Basin. Two types of correction models of heavy hydrocarbon loss for liquefrozen and room-temperature shales were determined by comparing the conventional and multistage Rock-Eval experiments, respectively. The light hydrocarbon loss correction model was obtained according to conventional Rock-Eval experiments on liquefrozen and room-temperature shales. Moreover, the estimation models of adsorbed, free, and movable amounts of oil were determined and validated by the oil saturation index (OSI) method. The results show that the total, adsorbed, free, and movable oil contents can be estimated well by these correction models. A case study from the Funing Formation, Subei Basin, indicates that the higher the content of total oil, the higher the amounts of free and movable oil, indicating that shale with more oil also has a more excellent mobile and developable potential. Organic matter is the main adsorbent for shale oil. Shales with TOC greater than 1.5% generally have greater free (movable) oil amounts, which may be the optimal target for shale oil exploration and exploitation. This study provides an innovative approach to correct the key parameters of shale oil resources, and thus, is crucial for the exploration and development of shale oil in the Funing Formation, Subei Basin.

Influence of oil structures on the component composition of free gases of potash reservoirs at the BPPU-4 mine field of PJSC “Uralkali”

The influence of oil structures on the content of heavy hydrocarbon gases in the component composition of free gases in the rocks of the overlying silvinite formations is considered. There is an assumption about the influence of reef formations on the overlying sedimentary deposits and the development of sub-vertical cracks, through which heavy hydrocarbon gases can penetrate into the overlying potash layers. The aim of the study is to study the relationship between the nature of the distribution of heavy hydrocarbon gases and geological disturbances and the subsequent prediction of the gas-dynamic situation during the development of potash reservoirs. The method consists of drilling holes into the roof of the mine, sealing the hole with a sealer, and then taking gas from the sealed part to the sampler and analyzing it on a gas chromatograph. The highest values of heavy hydrocarbon gases were determined for the Bc, AБ and KpII formations at the BPPU-4 mine field of PJSC Uralkali.

Health Risk Factors of Emissions from Internal Combustion Engine Vehicles: An Up-to-Date Status of the Problem

Introduction: Motor transport with internal combustion engines powered by diesel fuel and gasoline is one of the main sources of ambient air pollution since its emissions pose an urgent medical and environmental challenge. The objective of the study was to identify priority pollutants from emissions of motor vehicles powered by internal combustion engines based on the results of a systematic review in order to substantiate the main preventive strategy to mitigate the associated public health adverse effects. Methods: We did keyword search for relevant publications in several electronic databases, such as the Russian Science Citation Index, CyberLeninka, Scopus, and WoS. Research papers published in 2000–2021 were selected for the analysis. Out of 103 topical full-text publications, 59 works met the criteria for inclusion in the systematic review. Results: We observed that atmospheric emissions of internal combustion engines represent a complex agglomeration of gases, vapors, and particulate matter. The chemicals present in the emissions impair the oxygen transport function by inhibiting cellular respiration, cause irritation of mucous membranes, have mutagenic and carcinogenic effects, contribute to the occurrence of acid rains and to global warming. The biological effect of airborne particles largely depends on their size. It has been established that an increase in the number of airborne particles with an aerodynamic diameter less than 10 μm is associated with the risk of endothelial inflammation, thrombosis, increased cell permeability, and DNA methylation. It has been also demonstrated that a 5 µg/m3 increment in ambient concentrations of fine particles (&lt; 2.5 μm) causes a 7 % increase in the mortality rate. At the same time, PM2.5 exposure-related risks of excess deaths from cardiovascular diseases are twice as high as those posed by exposure to PM10. Conclusions: Diesel and gasoline engine exhausts are a significant risk factor for human health. An effective preventive strategy should be aimed at replacing heavy hydrocarbon motor fuels by compressed gas using hydrogen cells and electric motors.

Production of Hydrogen From Heavy Hydrocarbons

The mechanism of the effect of an arc discharge on heavy hydrocarbon raw materials is studied in the work. The mechanism of formation of charged particles in micro-discharges with recessed electrodes is shock ionization. As a result of the interaction of hydrocarbon raw materials with an arc discharge, long hydrocarbon molecules are broken down, light hydrocarbons such as ethylene, hydrogen, and methane are formed. In the case of the organization of a micro-arc discharge, a gentle thermal regime also provides a gentle splitting of long hydrocarbon molecules, and in this case gasoline fractions of oil are formed in greater quantities compared to the case of exposure to raw materials by a conventional arc discharge.

Experimental Analysis and Performance Investigation of Immiscible Super-Critical CO2 Flooding Processes in Tight Oil Reservoir

CO2 flooding, a promising technique of enhanced oil recovery, is widely used for its capability of boosting oil recovery, and reducing greenhouse gas emissions. In this study, the oil displacement performance of supercritical CO2 is tested in laboratory under immiscible flooding. The results show that: Supercritical CO2 improves oil recovery, by virtue of its low viscosity, high diffusivity, and easy dissolution. With the same pore volume (PV), supercritical CO2 flooding significantly boosted the oil recovery factor. The factor reached the maximum, when almost 1.5PV of CO2 was injected. As CO2 moved from the gas phase to the supercritical state, the oil displacement efficiency increased by 10%. To obtain the same oil recovery factor, non-supercritical flooding needed to inject more CO2 than supercritical flooding. Light hydrocarbon components (C1-7) in crude oil were gradually extracted before CO2 breakthrough, while heavy hydrocarbon components (C7+) were extracted mainly after CO2 breakthrough. In addition, supercritical CO2 flooding extracted more intermediate hydrocarbons than critical CO2 flooding. To sum up, supercritical flooding outperforms non-supercritical flooding in injection performance, oil displacement efficiency, and oil exchange rate.

Kinetic study of the thermolysis process of oil sludge (atasu-alashankou) with nickel, cobalt and iron deposited on microsilicate

The object of research is the process of thermal degradation of oil sludge in the presence of heterogeneous catalysts. The creation of efficient technological processes for processing the organic part of oil sludge into motor fuels, raw materials for petrochemicals and the disposal of microsilicate is an important urgent task, the solution of which will allow to obtain a significant economic and environmental effect. The problem to be solved is to establish the general kinetic laws of the process of thermal degradation of oil sludge in the presence of microsilicate with deposited metals. The advantage of the Ozawa– Flynn–Wall method is that it is possible to determine the kinetic parameters for each value of oil sludge conversion, that is, for different stages of thermal degradation. The activation energy of oil sludge 67.1 kJ/mol, and with a catalyst 59 kJ/mol are calculated for each degree of conversion (α), respectively. The value of the correlation coefficient was (R2≥0.997) provides good convergence with experimental results. Compared with other methods of thermal processing of oil sludge, catalytic thermal degradation has a number of advantages: relatively low process temperatures (400–650 °C), low sensitivity to the composition of raw materials and the processing process, which meets all modern requirements of chemical production. Regularities of thermokinetic parameters of thermal decomposition of oil sludge were studied using raw materials obtained during the process of oil transportation, in the presence of catalyst with applied metal (nickel, iron, cobalt) to microsilicate. Obtained results of oil sludge decomposition kinetics can be used in creating a database for mathematical modeling of process of heavy hydrocarbon raw materials processing

РОЛЬ ЛЕТКИХ КОМПОНЕНТІВ У ПРОЦЕСІ ТЕРМАЛЬНОЇ ДЕCТРУКЦІЇ ТА ЗАПАЛЮВАННЯ БІОМАСИ ЛУШПИННЯ СОНЯШНИКА

The final composition of volatile components in the process of oxidative pyrolysis depends on the temperature level of the process. The gas output increases with the growth of hydrogen, methane and heavy hydrocarbons concentration in the process of pyrolysis in the range of 200-500°C. In this case, there is a noticeable decrease in undesirable impurities in the output of carbon dioxide and nitrogen in the fuel gas. The obtained data on the dynamics of thermal decomposition of biomass under heating conditions reflect the complex dependence of the yield of total gas individual components both on time and on the temperature of the process. The more volatiles contained in the source fuel, (the other things being equal) the faster the gas mixture ignites, and the more intensely it burns out. The composition and temperature of the gas mixture affects the pressure drop and auto-ignition temperature in the pyrolysis chamber. It was found that the lowest self-ignition temperature of a gas mixture is 490°C. A series of experiments to determine the critical condition for self-ignition at a constant temperature of 490°C and various initial pressures of the mixture (100-300 kPa) was carried out. It was found that the transition from a smooth increase in pressure of 90 kPa to an explosive one (up to 300-400 kPa) depends on the composition and temperature of the gas mixture. Therefore, the composition of the gas and its ignition temperature can be controlled by adjusting the mode of pressure increase in the reactor.

Biogenic Methane Accumulation and Production in the Jurassic Low-Rank Coal, Southwestern Ordos Basin

Geological conditions are the key for coalbed methane (CBM) accumulation and production. However, the geological feature of CBM accumulation and production in the Jurassic of Ordos Basin lacks systematic and detailed evaluation, resulting in poor CBM production in this area. This study has determined the genetic types of gas according to geochemistry characteristics of the gas, the geological factors to control CBM accumulation and production performance were revealed, and a comprehensive method was established to evaluate favorable areas based on 32 sets of CBM well production data from Jurassic Yan’an Formation. The results show the coal macerals are rich in inertinite (41.13~91.12%), and the maximum reflectance of vitrinite (Ro,max) in coal is 0.56~0.65%. According to gas compositions and carbon isotopes analysis, the δ13C(CH4) is less than −55‰, and the content of heavy hydrocarbon is less than 0.05%. The value of C1/(C2 + C3) is 6800~98,000, that is, the CBM is a typical biogenic gas of low-rank coal. The CBM accumulation model is the secondary biogenic on the gentle slope of the basin margin, in which gas content is closely related to buried depth and hydrodynamic environment, i.e., the high gas content areas are mainly located in the groundwater weak runoff zone at the burial depth of 450 m~650 m, especially in the syncline. Meanwhile, gas production mainly depends on the location of the structure. The high gas production areas of vertical wells were distributed on the gentle slope with high gas content between anticline and syncline, and the horizontal wells with good performance were located near the core of the syncline. According to the above analysis combined with the random forest model, the study area was divided into different production favorable areas, which will provide a scientific basis for the CBM production wells.

Mixed Contaminants: Occurrence, Interactions, Toxicity, Detection, and Remediation.

The ever-increasing rate of pollution has attracted considerable interest in research. Several anthropogenic activities have diminished soil, air, and water quality and have led to complex chemical pollutants. This review aims to provide a clear idea about the latest and most prevalent pollutants such as heavy metals, PAHs, pesticides, hydrocarbons, and pharmaceuticals—their occurrence in various complex mixtures and how several environmental factors influence their interaction. The mechanism adopted by these contaminants to form the complex mixtures leading to the rise of a new class of contaminants, and thus resulting in severe threats to human health and the environment, has also been exhibited. Additionally, this review provides an in-depth idea of various in vivo, in vitro, and trending biomarkers used for risk assessment and identifies the occurrence of mixed contaminants even at very minute concentrations. Much importance has been given to remediation technologies to understand our current position in handling these contaminants and how the technologies can be improved. This paper aims to create awareness among readers about the most ubiquitous contaminants and how simple ways can be adopted to tackle the same.

Co-pyrolysis of municipal solid waste (MSW) and biomass with Co/sludge fly ash catalyst

Catalytic co-pyrolysis of municipal solid waste (MSW) and biomass pine sawdust (PSD) under sludge fly ash (SFA) could be a breakthrough towards the energy challenges and waste management. This paper aims to develop a unique cobalt-alkali-SFA (Co-A-SFA) catalyst, in order to investigate its influence under optimal operating conditions in a fixed bed reactor for syngas production. The catalytic activity was assessed under different Co loading and support ratios. The results indicated that in the presence of Co-A-SFA catalyst, gas production increased due to alkali pretreated fly ash catalyst. Moreover, increasing the Co loading from 5 wt% to 10 wt%, the syngas production increased irrespective of the individual feedstock ratios. Under catalytic conditions of 5 and 10 wt% the H2 yield to 25.4% and 28.3% for 50/50 MSW/PSD compared to 11.5 wt% under no catalyst. Catalytic co-pyrolysis of MSW and PSD also minimized the concentration of complex liquid compounds and heavy hydrocarbons. Therefore, this study establishes a new approach towards energy production and sustainable waste management through useful resource utilization of MSW, PSD and SFA. The outcomes acquired in this investigation showed that blended feedstock in co-pyrolysis of MSW and pine sawdust could enhance production of valuable syngas under SFA-based catalyst.

Characterization of Pyrolysis Kinetics of Continental Shale: Comparison and Enlightenment of the Parallel Reaction Model and the Overall Reaction Model

A total of nine immature–low maturity oil shale samples from Fushun and Maoming, the main oil shale producing areas in China, and three mature shale samples from the Jiyang Depression, China, were selected for use in hydrocarbon generation thermal simulation experiments in an open system and a closed system. The parallel first–order reaction kinetic model and the overall nth–order reaction kinetic model were used to calibrate the pyrolysis kinetic parameters of the samples. This comparative study revealed following conclusion. The generation period of the gaseous hydrocarbons (C1–5) was the longest, and the generation period of the heavy hydrocarbon (C14+) was the shortest. The activation energy of the hydrocarbon generation reaction was closely related to the maturity of the organic matter, i.e., the higher the maturity of the sample, the higher the activation energy of the reaction, which indicates that oil shale/shale oil conversion requires higher temperature conditions. The parallel first–order reaction model regards the hydrocarbon generation reaction as a series of first–order reactions, and it has a better fitting effect for the longer hydrocarbon generation period reactions, such as generating gaseous hydrocarbons (C1–5) and light components (C6–14) from organic matter. The overall nth–order reaction treats the reaction as a nth–order reaction, and the nth–order reaction has a better fitting effect for reactions with a narrow hydrocarbon generation window, such as generating heavy components from organic matter. In the process of generating hydrocarbons from organic matter, the order of the reaction is the sum of the orders of the sub–reactions. The more hydrocarbon–generating parent material, the higher order of hydrocarbon–generating reaction. The reaction order sequence of the generation of different hydrocarbons from organic matter is as follows: generation of gaseous hydrocarbons &amp;gt; generation of light hydrocarbons &amp;gt; generation of heavy hydrocarbons.

The Volume and Geochemical Characteristics of Desorption Gases From Wufeng–Longmaxi (O3w-S1l) Shale in the Xishui Area, North Guizhou, China

The Upper Ordovician–Lower Silurian Wufeng–Longmaxi (O3w-S1l) shale is widely distributed in the Xishui area, north Guizhou, China. However, the potential and characteristics of shale gases in the Xishui area are not well evaluated, which has limited the exploration of shale gas in this area. In this study, we collected 14 fresh core samples of Wufeng–Longmaxi Formations from Well XK-3 and conducted gas desorption experiments to evaluate the potential of shale gas resources in the Xishui area. After analyzing the chemical and isotopic composition of desorption gases, the origin and genesis of the shale gas were systematically studied. Our results show that the volume of desorption gases varies from 2.14 m3/t to 6.01 m3/t, with a mean value of 4.12 m3/t, showing great potential for shale gas in this area. The positive correlation between total organic carbon (TOC) and desorption gas volume indicates that organic matter provides the main pore volume for shale gas preservation. The desorption gases are very dry, which are mainly composed of methane (99.64‰–99.74%) with a very low content of ethane, and no nitrogen, carbon dioxide, and hydrogen sulfide are detected. Based on geochemical diagrams, the desorption gases are identified as oil-associated thermogenic gases. The carbon isotopic values of methane and ethane display reversal distribution, due to the mixing of primary gases from kerogen cracking and the secondary gases from retained oil cracking and further possible cracking of heavy gaseous hydrocarbons (C3H8—C5H12) at higher thermal maturity (Ro &amp;gt; 2.00%). After comparing with Jiaoshiba, Changning, Weiyuan, and Dingshan areas, the carbon isotopic values of shale gases of Wufeng–Longmaxi shale also show different features at different areas, which are mainly controlled by the thermal maturity levels of the shale.

Systematic study on dynamic pyrolysis behaviors, products, and mechanisms of weathered petroleum-contaminated soil with Fe2O3

Weathered petroleum-contaminated soil (WPCS) with a high proportion of heavy hydrocarbons is difficult to remediate. Our previous research demonstrated that Fe2O3-assisted pyrolysis was a cost-effective technology for the remediation of WPCS. However, the pyrolysis behaviors, products, and mechanisms of the WPCS with Fe2O3 are still unclear. In this study, a combination of Thermogravimetric–Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) techniques were used to explore these pyrolysis characteristics. The thermal desorption/degradation of light and heavy hydrocarbons in the WPCS mainly occurred at 200–400 °C and 400–550 °C, respectively. The activation energy of thermal reaction of heavy hydrocarbons was decreased in the presence of Fe2O3 during the WPCS pyrolysis processes. In the process, the released inorganic gaseous products were mainly H2O and CO2, while the released organic gaseous compounds were primarily cycloalkanes, alkanes, acids/esters, alcohols, and aldehydes. Compared with the WPCS pyrolysis without Fe2O3, the yields of gaseous products released during the WPCS pyrolysis with Fe2O3 were reduced significantly, and some gaseous products were even not detected. This phenomenon was contributed by the following two reasons: 1) heavy hydrocarbons in the WPCS were more easily transformed into coke in the presence of Fe2O3 during pyrolysis; 2) some released gaseous products were reacted with Fe2O3 and fixed on the soil particles. Therefore, the WPCS pyrolysis with Fe2O3 can effectively reduce the burden of tail gas treatment. Criado method analysis results suggested that the reaction mechanism of heavy hydrocarbons during the WPCS pyrolysis with Fe2O3 was rendered as the synergic effects of diffusion, order-based, and random nucleation and growth reactions.

Removal of heavy metals and hydrocarbons by microalgae from wastewater in the steel industry

Steel-industry effluents contain hazardous compounds such as heavy metals and hydrocarbons, which can damage the environment. Traditional remediation technologies generate secondary impacts and, therefore, developing more sustainable methods is imperative. In this work, the tolerance capacity of Tetradesmus obliquus, Chlorella sorokiniana, Chlorella vulgaris, Arthrospira platensis and Arthrospira maxima (spirulina) to steel hot-rolling wastewater was tested through their exposure to increasing concentrations of residue. Based on the results obtained, A. maxima was cultured in presence of wastewater and scaled to semi-industrial production systems. Influence of microalgae growth on wastewater composition was evaluated by the end of the experiment by measuring concentrations of contaminants of concern (iron and hydrocarbons). Results showed a reduction of hydrocarbons and iron of 75 and 97.9%, respectively. The findings obtained in this study stablish that spirulina cultures might be used as a novel and environmentally sustainable bioremediation tool for steel-industry wastewater.