Low Molecular Weight Hydrocarbons Research Articles

Measuring aliphatic hydrocarbons in sediments by direct thermal desorption-gas chromatography-mass spectrometry: Matrix effects and quantification challenges

Direct sample introduction thermal desorption (TD) coupled to GC–MS was investigated for the analysis of paraffinic hydrocarbons (HCs) from polluted sediments. TD-GC–MS is sometimes used for analysing paraffinic HCs from atmospheric particles but rarely for their direct desorption from sediments. So, the new TD methodology, applied to sediments, required development, optimization and validation. A definitive screening experimental design was performed to discriminate the critical factors on TD efficiency, from model sediments containing various organic matter (OM) amounts. Low molecular weight HCs had extraction behaviours markedly different from high molecular ones (HMW-HCs), but a compromise was found using very few sediment amount (5 mg), high temperature rate (55 °C min−1) and final temperature (350 °C). Linear HCs (n-C10 to n-C40) could be quantified using the matrix-matched calibration method, with very low detection limits (3.8–13.4 ng). The amount of the overall paraffinic alkanes was also determined as a sum of unresolved components between predefined equivalent carbon ranges. The developed solventless methodology was compared to an optimized solvent microwave assisted extraction (MAE). Matrix effects could be higher for TD compared to MAE but it depended on sediment matrix. When matrix effect was strong, particularly on HMW-HCs signal depletion, a dilution with pure non-porous sand was favourable for accurate quantification. The sum of resolved and unresolved HCs gave comparable results between MAE and TD extractions, with an exception of alkanes greater than C30 which were less quantitatively extracted via TD. However, TD-GC–MS was more sensitive than MAE-GC–MS. So TD-GC–MS is useful for analyzing sediments containing a great range of paraffinic HCs (C9-C34) and it has the advantages of being fully automated, with few sample preparation and operator intervention, using very low amounts of solvent, and generating few wastes.

Catalytic hydrothermal liquefaction of Camelina sativa residues for renewable biogasoline production

ABSTRACT Camelina sativa plant residue was used as feedstock for the production of biogasoline (a mixture of paraffinic and olefinic hydrocarbons) by catalytic hydrothermal liquefaction (cHTL) process. The experiments were conducted at temperature range 200–375°C and pressure range 10–19 MPa. Molecular hydrogen was added for the hydro-deoxygenation processes. Various experiments were performed to understand the contributions of process parameters such as temperature, pressure, hydrogen, and retention time on reaction conversion and products distribution. This was followed by screening of different catalyst supports – γ-Al2O3, HZSM-5, SiO2-Al2O3, SBA-15, and Al2O3-HZSM-5 to understand their impacts as well as catalytic activities. The Al2O3/HZSM-5 exhibited the best properties and was impregnated with a varying range of cobalt metal for the HTL of Camelina sativa. The 5%Co/γ-Al2O3-HZSM-5 catalyst exhibited highest liquefaction conversion (79%) and biogasoline yield (43%) at optimized reaction conditions due to the presence of strong brønsted acidity on the catalyst were that enhanced both the hydrocarbon cracking and hydrogenation leading to the production of low boiling point and low molecular weight hydrocarbon within the boiling point range of fossil gasoline. Across all the data point used in the work, the average deviation was within ± 3%, these are mostly indicated by the error bars.

The content and composition of organic compounds in the bottom sediments of the Norilsk-Pyasina water system one year after the accidental spill of diesel fuel

One year after the emergency diesel fuel spill in Norilsk, hydrocarbon concentrations in bottom sediments of the Norilsk-Pyasina water system decreased. However the average concentrations of hydrocarbons in surface sediments decreased in the same sequence (μg/g) as in 2020: the mouth of the Ambarnaya R. (835, σ = 1788) > Bezymyanny Cr.–the Daldykan R.–the Ambarnaya R. (306, σ = 273) > the Pyasina R. (23, σ = 20) > the Pyasino Lake (12, σ = 8). Concentrations decreased due to degradation of low molecular weight hydrocarbons. The content of polycyclic aromatic hydrocarbons in 2021 also changed in a smaller range (0–1027 ng/g) than in 2020 (0–3865 ng/g). Petroleum origin of polycyclic aromatic hydrocarbons in the sediments of the Ambarnaya R. (including the mouth), Bezymyanny Cr. and the Daldykan R. is confirmed by the dominance of alkylated naphthalene homologues in their composition. Hydrocarbons accumulation in some layers of the sedimentary column is caused not only by the spill of diesel fuel, but also by the organic matter from the surrounding swamps, from wetlands and floodplain lakes, as well as by the burial of the surface layer by the 2021 flood.

Spatial evolution and temporal stability of hydrothermal processes at sediment-covered spreading centers: Constraints from Guaymas Basin, Gulf of California

The Guaymas Basin, Gulf of California is a hydrothermally active sediment-covered oceanic spreading center in the early stages of rifting. Hot-spring fluids were collected from its southern trough in 1998, 2003, and 2008 and analyzed for the concentration and isotopic composition of organic and inorganic aqueous species to assess subseafloor geochemical processes. Fluids discharged from the seafloor through hydrothermal edifices with measured temperatures of 91 to 317 °C. In general, fluids exiting larger structures were characterized by higher temperatures than fluids venting from smaller structures. Measured pH (25 °C) ranged from 5.7 to 7.1. Endmember fluids were characterized by near-zero concentrations of Mg and SO4, depletions in Na, and enrichments in K, Ca, and Cl relative to seawater, reflecting extensive interaction with sediment during circulation. Thermal maturation of sedimentary organic matter resulted in the addition of abundant ΣNH4+, ΣCO2, CH4, short-chain n-alkanes, and carboxylic acids to solution. Organic compounds added to fluids during recharge pass through high temperature deep-seated reaction zones and reach high levels of thermal maturity while others may be added by entrainment of lower temperature sedimentary pore fluids in hydrothermal upflow zones.The relative abundance of many organic compounds mobilized during hydrothermal alteration is consistent with metastable states of thermodynamic equilibrium that likely record subseafloor temperature conditions. The isotope composition of low molecular weight hydrocarbons and elevated concentrations of dissolved Cl suggest that temperatures may have exceeded the two-phase boundary for seawater and subsequently cooled before discharging at the seafloor. Periods of high temperature fluid-sediment or fluid-rock interaction followed by cooling may provide a mechanism for the aqueous mobilization and concentration of sulfide-forming metals in subseafloor mineral deposits. Fluid compositions have remained constant at the southern trough of Guaymas Basin for at least 26 years, indicating decadal stability in the physical and chemical conditions in subseafloor environments as well as the km-scale regional recharge zones containing unaltered sediment.

Revealing the mechanism of nicotine pyrolysis: Insights from DFT calculations

Nicotine is the most abundant alkaloid in tobacco, so it is of great significance to reveal its pyrolysis mechanism for further understanding of tobacco pyrolysis mechanism. The mechanistic pathways for nicotine decomposition were constructed according to density functional theory (DFT) calculations and pyrolysis experiments. The M062X/6–31 +G (d, p) method and basis set were selected for performing calculations. The results indicated that there were four bonds in nicotine molecule that were susceptible to cleavage with the order of: C7-N11 > C10-N11 > C12-N11 > C4-C7. Combining previous pyrolysis experiments, four possible pathways for nicotine pyrolysis under a radical system were analyzed, and the activation energy of each pathway was compared to determine the most probable reaction. After the cleavage of C7-N11 and C10-N11 bonds, low molecular weight hydrocarbons and some nitrile compounds were generated. C12-N11 bond cleavage produced more complex substances, such as 2-methyl-1H-pyrrole, 7H-cyclopentapyridine, and quinoline, which required the highest activation energy. C4-C7 bond cleavage led to the formation of pyridine, substituted pyridines, and pyrrole. Among them, the binding energy of 3-pyridinecarbonitrile was the highest (−137.75 kcal/mol). Finally, the mechanistic pathways for nicotine decomposition were validated through nornicotine pyrolysis. It revealed that the highest relative content of 3-ethenylpyridine and relatively low content of quinoline in nornicotine pyrolysis products were consistent with the activation energy analysis for nicotine decomposition pathways, which further demonstrated the theoretical and experimental support for the mechanistic pathways of nicotine decomposition.

CHANGES IN CONTENT AND COMPOSITION OF HYDROCARBONS IN THE BOTTOM SEDIMENTS OF THE NORILO-PYASINSK WATER SYSTEM A YEAR AFTER THE EMERGENCY DIESEL FUEL SPILL

One year after the emergency diesel fuel spill in Norilsk, hydrocarbon concentrations in bottom sediments of the Norilo-Pyasinsky water system decreased. But on average in the areas they decreased in the same sequence (µg/g) as in 2020: the mouth of the Ambarnaya R. (835, σ = 1788) Bezymyanny Cr. – the Daldykan R. – the Ambarnaya R. (306, σ = 273) Pyasina R. (23, σ = 20) Lake Pyasino (12, σ = 8). Concentrations decreased due to degradation of low molecular weight hydrocarbons. The content of polycyclic aromatic hydrocarbons in 2021 also changed in a smaller range (0–1027 ng/g) than in 2020 (0–3865 ng/g). Petroleum origin of hydrocarbons in the sediments of the Ambarnaya R. (including the mouth), Bezymyanny Cr. and Daldykan R. confirms the dominance of alkylated naphthalene homologues in their composition. Hydrocarbons accumulation in some horizons of the sedimentary strata is caused not only by seepage of diesel fuel, but also to the introduction of organic matter from the surrounding swamps from wetlands and floodplain lakes, as well as the burial of the surface layer by the 2021 flood.

Определение взрывоопасности сжиженного природного газа

Excess explosion pressure is one of the main indicators characterizing the explosiveness of a gas. Precise determination of the dependence of the explosion pressure on the distance allows to ensure the safe layout of production facilities with minimal economic costs. Every year, all over the world and in Russia in particular, there is an increase in energy consumption. There is a shift in the global energy system towards the large-scale use of low-carbon energy sources, which is caused by the policy of decarbonization of the fuel and energy complex as part of the fight against global warming. The advantage of operating natural gas in a liquefied state led to the development of the liquefied natural gas market in Russia, with the development of which the risk of accidents at the facilities in this segment of the economy increases. However, the existing methods do not allow calculating the explosion pressure for a mixture of low molecular weight hydrocarbons, which is liquefied natural gas. A new formula for calculating the explosion pressure is proposed considering the composition of the liquefied natural gas. The conducted studies showed the possibility of using the proposed formula to determine the parameters of the explosion of mixtures of low molecular weight hydrocarbons, in particular, liquefied natural gas. It is shown that, despite the linear dependence of the change in the maximum explosion pressure of methane on the change in the percentage of impurities of its homologues, the expected composition of the mixture components differs from that calculated according to the Le Chatelier rule, which can be taken into account in further studies. A comparative analysis of the explosion pressure according to the proposed methodology and the standard showed deviations for grades V, B, and A were 34.99; 20.45; and 2.1%, respectively, which significantly reduces the possible consequences of the explosion and creates a significant error in determining the safe distance. In order to exclude the possibility of obtaining underestimated indicators of the explosion pressure of the liquefied natural gas, it is recommended to use an adjusted methodology.

Bacterial volatiles as PGPRs: Inducing plant defense mechanisms during stress periods

The increase in population and food demand has led to the excessive utilization of chemical fertilizers. These fertilizers, in turn, affected the soil properties and decreased the fertility of the soil. The side effects of these chemicals have forced scientists to focus on plant growth-promoting rhizobacteria (PGPR) for sustainable farming. Some microbes and plants have a mutual relationship, and they use to help each other in various ways Rhizobacteria that promote plant growth enhance health of the plant and growth by increasing nutrient accessibility and assisting plants during abiotic and biotic stress. By direct or indirect mechanisms, the bacterial releases of volatile organic compounds (VOCs) are crucial in boosting plant development and disease resistance. The release of a range of low-molecular weight hydrocarbons, including the growth-promoting volatile organic compounds, 3‑hydroxy-2-butanone (acetone), 2,3-butanediol, 2-pentylfuran, or dimethylhexadecylamine, was found by chemical analysis of bacterial volatile emissions. The plants provide nutrients and shelter to the microbes. Therefore, PGPRs play a vital role in sustainable agriculture In this review, the mechanism of action of VOCs for growth promotion and how they trigger the plant defense mechanism during biotic and abiotic stress will be addressed.This review will addressthe mechanism of action of VOCs for growth promotion and how they trigger the plant defense mechanism during biotic and abiotic stress.

Development of a simple and efficient oil-soluble nanocatalytic system for aquathermolysis upgrading of heavy crude oil

Catalytic aquathermolysis is one of the key and cost-effective chemical method for recovering heavy oil. This process transforms the asphaltene and resin compounds of the oil into lighter fractions. Oil-soluble transition metal-based catalysts have been reported as efficient catalysts that improve the viscosity reduction efficiency of the aquathermolysis process. Previous studies have mainly focused on using long alkyl chains as oil-soluble ligands to prepare the catalysts. However, aromatic ligands that effectively interact with asphaltene and resin fractions have not been extensively studied. In other words, the molecular structure of ligand used in the catalyst synthesis significantly changes its activity in aquathermolysis. This study aims to fill this gap using catechol as a novel ligand to develop oil-soluble catalyst (Ni-OSC), which can interact with heavy oil fractions during aquathermolysis. Ni-OSC decreased the content of resin and asphaltene by 32.1% and 26.5%, respectively, and increased the amounts of saturated and aromatic hydrocarbons by 19.6% and 22.9%, respectively, compared to heavy oil. Moreover, a GC–MS study indicated that low molecular weight hydrocarbons in the composition of heavy oil increased, and the relative content of alkanes raised to 79% in the presence of Ni-OSC. The catalyst also increased the concentration of alkylbenzenes and naphthalenes in the composition of aromatic compounds, improving the quality and recovery of heavy oil. Furthermore, the viscosity of heavy oil was considerably reduced, and a maximum hydrogen to carbon ratio of 2.03 was observed in Ni-OSC system. To the best of our knowledge, this is the highest reported hydrogen-to-carbon ratio for catalytic aquathermolysis of heavy oil using oil-soluble catalysts.

Unraveling the catalytic activity of CaClOH-rich incineration fly ash in the pyrolysis of single-use plastics

In recent years, increased population and economic growth have resulted in an explosion in demand, production, and disposal of non-biodegradable commodity plastics. Pyrolysis, the anaerobic thermochemical breakdown of plastics such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) into lower molecular weight hydrocarbons with applications as fuels, waxes, and lubricants, has emerged as one of the most promising industrial technologies for the end-of-life treatment of plastics. While a range of inorganic materials have shown efficacy in catalyzing plastic pyrolysis and reducing their energetic demands, the use of existing inexpensive waste materials such as incineration fly ash (IFA) for this application has largely been overlooked. Herein, we demonstrate the viability of IFA as a catalyst for the pyrolysis of PE, PP, and PS, which account for almost 60% of all the waste plastics produced globally. The presence of IFA improved reaction conversions and liquid yields and resulted in positive outcomes for the pyrolysis of real-life plastic waste such as high density polyethylene (HDPE) detergent bottles and low density polyethylene (LDPE) plastic bags. Specifically, the pyrolysis of virgin HDPE pellets with IFA showed increased conversion from 46.7% to 92.8% and liquid yield from 35.1% to 81.6%, respectively. Through a set of control experiments, we determined that the catalytic activity of IFA could be attributed mainly to calcium hydroxychloride (CaClOH), which differed from other common calcium-containing minerals such as calcium oxide (CaO) and calcium chloride (CaCl2). Our findings demonstrate the unique catalytic possibilities offered by overlooked waste materials such as IFA in the upcycling of single-use plastics into liquid hydrocarbons and offer new insights on the use of different calcium-based catalysts for plastic pyrolysis.

Isolation, identification, and screening of biosurfactant-producing and hydrocarbon-degrading bacteria from oil and gas industrial waste

Qatar is one of the biggest oil and gas producers in the world, coupled with it is challenging environmental conditions (high average temperature: >40 °C, low annual rainfall: 46.71 mm, and high annual evaporation rate: 2200 mm) harbors diverse microbial communities that are novel and robust, with the potential to biodegrade hydrocarbons. In this study, we collected hydrocarbon contaminated sludge, wastewater and soil samples from oil and gas industries in Qatar. Twenty-six bacterial strains were isolated in the laboratory from these samples using high saline conditions and crude oil as the sole carbon source. A total of 15 different bacterial genera were identified in our study that have not been widely reported in the literature or studied for their usage in the biodegradation of hydrocarbons. Interestingly, some of the bacteria that were identified belonged to the same genus however, demonstrated variable growth rates and biosurfactant production. This indicates the possibility of niche specialization and specific evolution to acquire competitive traits for better survival. The most potent strain EXS14, identified as Marinobacter sp., showed the highest growth rate in the oil-containing medium as well as the highest biosurfactant production. When this strain was further tested for biodegradation of hydrocarbons, the results showed that it was able to degrade 90 to 100% of low and medium molecular weight hydrocarbons and 60 to 80% of high molecular weight (C35 to C50) hydrocarbons. This study offers many promising leads for future studies of microbial species and their application for the treatment of hydrocarbon contaminated wastewater and soil in the region and in other areas with similar environmental conditions.

Thermodynamic and Experimental Substantiation of the Possibility of Formation and Extraction of Organometallic Compounds as Indicators of Deep Naphthogenesis

In this article, typomorphic associations of microelements in carbonaceous caustobioliths and oils are defined as indicators of naphthogenesis based on the analytical survey of the literature and our own research. Various approaches to the studying of crude oil genesis from the position of abiotic and complex approaches (polygenesis) are considered. Such approaches are relevant to the prospect and development of offshore oil deposits, localized at ultra-deep levels. For deep deposits, the most prominent hypothesis of oil origin is the abiogenious theory. In the foundation of that approach lays the assumption that hydrocarbons are formed mainly due to reactions of the formed mantle gases and the host rock. Key factors for these reactions to proceed are specific conditions concerning temperature, pressure, and specific catalysts. The article presents the results of thermodynamic and quantum-chemical modeling of the possibility of the organic and organometallic compound formation using the software package HSC Chemistry 6.0. Pointed out the possibility of a low molecular weight hydrocarbon formation due to the contact of ascending flows of mantle gases with cooling natural barriers. The primary synthesis proceeds with the interaction of fluid forms of H2, CO2, and H2S. The estimation of the bonding energy depending on the structure of organometallic compounds was performed using the Avogadro software package. The program used the method of bond potential energy minimization to find the most stable structure of molecules. The metals nickel and vanadium, as the main companion metals of oil, are of the most interest from the position of analysis of their form of existence in the possible formation of hydrocarbons. Vanadium’s and nickel’s accumulation in asphaltene fractions of oils, probably, is caused by complex compounds of metalloporphyrin’s formation. In addition, the high sulfur content is probably associated with polymerization of organic molecules due to the formation of di-sulphide bonds. The method of cavitation extraction of organometallic compounds from oil and complex mineral–oil raw materials has been developed for experimental confirmation of microelements the extraction capability from oil raw materials.

COMPARISON OF DIFFERENT SOLID PHASE MICROEXTRACTION FIBERS IN EXTRACTION OF VOLATILE COMPOUNDS FROM ADIPOSE TISSUE

The volatile compounds (VCs) in headspace of adipose tissues (perirenal, tail, caul) were extracted by solid-phase microextraction (SPME) fiber coated with carboxen/ polydimethylsiloxane (CAR/PDMS) or divinylbenzene/ carboxen/ polydimethylsloxane (DVB/CAR/PDMS). In extraction with CAR/PDMS coating compared to DVB/CAR/PDMS, more VCs were obtained in perirenal (53 versus 41), tail (51 vs 47) and caul (35 vs 33) fats. Increased retention index for aldehydes increased the adsorption on DVB/CAR/PDMS. This fiber also provided a good yield for carboxylic acids. CAR/PDMS fiber could be recommended for VCs from adipose tissues if the goal is to identify aldehydes, especially fatty acid oxidation products and low molecular weight hydrocarbons, as well as greater number of VCs. However, in case of targeting carboxylic acids, esters, and also high molecular weight aldehydes, DVB/CAR/PDMS could be utilized due to its high affinity for mentioned compounds. Furthermore, the optimum extraction time should be studied to determine the time for VCs to reach equilibrium.

Biologically bound nickel accelerated de-polymerization of polyethylene to high value hydrocarbons and hydrogen

The synergy of Ni-phytocat and microwave driven process leads to highly desirable monocyclic aromatics and low molecular weight hydrocarbons, and H2, thereby paving the way to harness complete circular chemical potential of plastic waste.

Reducing the viscosity of missan heavy crude oil using combinations of low molecular weight hydrocarbon compounds

This work studied the facilitation of the transportation of Missan heavy crude oil characterized with high viscosity 84.61 cp at 15 °C, low API 23.1, by reducing its viscosity from break down asphaltene agglomerates using five solvents with some novel combinations of chemical additives were used for this study (naphtha & toluene, naphtha & xylene, naphtha & kerosene, toluene & kerosene, and xylene & kerosene).The viscosity of crude oil was measured after being treated with these chemicals at different concentrations (4, 8, and 12 weight%) and temperatures 15, 25, 35, and 45 °C. It has been found that increasing the concentration of naphtha with xylene from 4% to 12% causes a decrease in viscosity, from 48.62 cp at 15°C to 30.11 cp. The viscosity of a mixture of naphtha and kerosene drops from 50.15 cp at 15°C to 31.70 cp when the concentration is raised from 4% to 12%. The addition of toluene to kerosene causes the viscosity to drop from 51.76 cp at 15°C to 33.67 cp when the concentration of toluene is raised from 4% to 12%. Increasing the xylene concentration from 4% to 12% in kerosene led to a decrease in viscosity from 53.65 cp at 15°C to 34.88 cp at the same temperature. The findings of the present work could be applied to the petroleum industry for the purpose of transporting heavy oil of Missan or any other heavy crude.

Nitrogen dependence of rhamnolipid mediated degradation of petroleum crude oil by indigenous Pseudomonas sp. WD23 in seawater.

Effect of oil spills on living forms demands for safe, ecofriendly and cost-effective methods to repair the damage. Pseudomonads have exceptional tolerance to xenobiotics and can grow at varied environmental conditions. This study aims at biosurfactant mediated degradation of petroleum crude oil by an indigenous Pseudomonas sp. WD23 in sea water. Pseudomonas sp. WD23 degraded 34% of petroleum crude oil (1.0% v/v) on supplementation of yeast extract (0.05g/L) with glucose (1.0g/L) in seawater. The strain produced a biosurfactant which was confirmed as a rhamnolipid (lipid: rhamnose 1:3.35) by FT-IR, LCMS and quantitative analysis. Produced rhamnolipid had low CMC (20.0mg/L), emulsified petroleum oils (75-80%) and had high tolreance to varied conditions of pH, temperature and ionic strength. OFAT studies were performed to analyse the effect of petroleum crude oil, glucose, inoculum, yeast extract, pH, agitation speed and incubation time on degradation by Pseudomonas sp. WD23. Petroleum crude oil and glucose had significant effect on biodegradation, rhamnolipid production and growth, further optimized by central composite design. At optimum conditions of 3.414% v/v PCO and 6.53g/L glucose, maximum degradation of 81.8±0.67% was observed at pH 7.5, 100 RPM, 15.0% v/v inoculum in 28 days, with a 3-fold increase in biodegradation. GCMS analysis revealed degradation (86-100%) of all low and high molecular weight hydrocarbons present in petroleum crude oil. Hence, the strain Pseudomonas sp. WD23 can be effectively developed for management of oil spills in seas and oceans due to its excellent degradation abilities.

Catalytic Fast Pyrolysis of JP-10 and 3-Carene Using Analytical Py-GC/MS for the Production of Low Molecular Weight Hydrocarbons

Catalytic Fast Pyrolysis of JP-10 and 3-Carene Using Analytical Py-GC/MS for the Production of Low Molecular Weight Hydrocarbons

Insights into removal efficiency and mechanism of microwave remediation of soils contaminated with polyaromatic hydrocarbons of low molecular weight assisted by bluecoke-based conditioner

Microwave remediation of polyaromatic hydrocarbons-contaminated soils has garnered extensive attention owing to its cost effectiveness, time saving, homogeneous heating, and low energy consumption. The prepared bluecoke-based conditioner (KHCO3@BC) was used in this study to enhance microwave remediation and improve the naphthalene (NA) removal efficiency and soil properties. We investigated the optimal conditions, including the heating time, microwave power, bluecoke-based conditioner, initial concentration of NA, and moisture content of the soils. We evaluated the removal efficiency of NA and compared the remediation products after the addition of bluecoke, KHCO3, and KHCO3@BC conditioners. The results showed that the removal efficiency of NA reached 96.46% under the following optimized conditions: heating time of 20 min, microwave power of 700 W, 2 g of KHCO3@BC conditioner, initial NA concentration of 1 wt%, and soil moisture content of 4 wt%. The KHCO3@BC conditioner improved the contents of total K and fast-acting K during microwave remediation, and the mechanical components of the remediation soils were also optimized significantly. We proposed a feasible mechanism and evaluated the main reasons for the removal of NA from the soils based on the mechanical components of remediation soil and the remediation products, namely, gas stripping, boiling vaporization of NA, and breakage of soil grains by thermal stress.

Integrative description of changes occurring on zebrafish embryos exposed to water-soluble crude oil components and its mixture with a chemical surfactant

The effects of crude oil spills are an ongoing problem for wildlife and human health in both marine and freshwater aquatic environments. Bioassays of model organisms are a convenient way to assess the potential risks of the substances involved in oil spills. Zebrafish embryos (ZFE) are a useful to reach a fast and detailed description of the toxicity of the pollutants, including both the components of the crude oil itself and substances that are commonly used for crude oil spill mitigation (e.g. surfactants). Here, we evaluated the survival rate, as well as histological, morphological, and proteomic changes in ZFE exposed to Water Accumulated Fraction (WAF) of light crude oil and in mixture with Dioctyl Sulfosuccinate Sodium (DOSS, e.g. CEWAF: Chemically Enhanced WAF), a surfactant that is frequently used in chemical dispersant formulations. Furthermore, we compared the hydrocarbon concentration of WAF and CEWAF of the sublethal dilution. In histological, morphological, and gene expression variables, the ZFE exposed to WAF showed less changes than those exposed to CEWAF. Proteomic changes were more dramatic in ZFE exposed to WAF, with important alterations in spliceosomal and ribosomal proteins, as well as proteins related to eye and retinal photoreceptor development and heart function. We also found that the concentration of high molecular weight hydrocarbons in water was slighly higher in presence of DOSS, but the low molecular weight hydrocarbons concentration was higher in WAF. These results provide an important starting point for identifying useful crude-oil exposure biomarkers in fish species.

HYDROCRAKING OF HEAVY DISTILLATE INTO CLEAN DIESEL OIL USING Ni-Mo/Al2O3 CATALYST

Diesel oil is high pollution fuel and the quality of this fuel must he improved to obtain clean diesel oil Crude oil production and its quality tend to decrease. Light fuel oil demand rate is higher than that of residual fuel. Diesel oil produced in the refineries generally consists of predominantly straight-run diesel oil: however, compounds such as thermally and catalytically cracked diesel oils are sometimes included. The quality of straight-run diesel oil, such as hydrocarbon types and sulfur content, will in general reflect the nature of crude oil. Cracked stocks either thermal or catalytic cracked diesel oils, contain higher percentage of aromatic, olefin and sulfur contents and these cracked diesel products must be hydrogenated prior to rounting to final products. The passage of the Clean Air Act Amendment of 1990 in the U.S.A has forced American refineries to install new facilities to comply with stricter specifications for fuels such as gasoline and diesel oil. Hydrocracking processes are a combination of desulfurization and conversion developed primary to process feeds having a high content of unsaturated hydrocarbons (olefin and polycyclic aromatics) and non-hydrocarbon compounds (sulfur and nitrogen compounds) with a bifunctional catalyst. A variety of bifunctional catalysts and processing designs may be used commercially depending on the feedstock used and desired products. Influence of both feedstock compositions (paraffinic and non-paraffinic vacuum distillate, and wax) and the acidity of bifunctional catalysts on the performance of hydrocracked diesel oil products are discussed briefly in this paper. Low yield or selectivity of diesel oil products by high catalyst acidity, it is suggested that the higher secondary splitting has taken place in converting cracked products into large amounts of low-molecular weight hydrocarbons such as gasoline and LPG. High diesel index product of the paraffinic feedstock due to the high paraffin content of the produced diesel oil.