Experimental study and machine learning modeling of water removal efficiency from crude oil using demulsifier

This study deals with the investigation of the water removal efficiency (WRE) from crude oil using a commercial demulsifier. The impacts of time, demulsifier concentration, and temperature on WRE were experimentally studied. The results implied the fact that temperature plays a substantial role in the demulsification and has a direct correlation with WRE. In addition, while increasing the concentration up to 40 ppm contributed to reaching a higher WRE, it did not have positive effects on efficiency at higher concentrations (overdose) and just led to more demulsifier consumption. The concentration dependence of WRE was also diminished at high temperatures. At higher levels of temperature and concentration, the time required to reach a high WRE was noticeably reduced. In order to generalize the findings of this study, the measured experimental data were employed to design predictive methods for WRE based on two smart soft-computing paradigms, including Multilayer perceptron (MLP) and Gaussian process regression (GPR). Despite the high accuracy of both models, the MLP model presented the best consistencies with experimental data with average absolute relative error and relative root mean squared error of 0.84%, and 0.01%, respectively during the testing (validation) step. Also, a visual description through the contour diagram confirmed the capability of the recently proposed models to describe the physical variations of WRE under various operating conditions. Ultimately, a sensitivity analysis based on the MLP model was undertaken to shed light on the order of significance of operational factors in controlling WRE. Overall, the findings of the current research, in turn, have a satisfactory contribution to the efficient design of the water removal process from crude oil based on demulsifiers.

Retz.) Sm.: a suitable plant species for remediation of crude oil and mercury-contaminated soil

The aim of this study was to evaluate the efficiency of Costus speciosus (Koen ex. Retz.) Sm. in the degradation of crude oil and reduction of mercury (Hg) from the contaminated soil in pot experiments in the net house for 180 days. C. speciosus was transplanted in soil containing 19150 mg kg-1 crude oil and 3.2 mg kg-1 Hg. The study includes the evaluation of plant biomass, height, root length, total petroleum hydrocarbon (TPH) degradation, and Hg reduction in soil, TPH, and Hg accumulation in plants grown in fertilized and unfertilized pots, chlorophyll production, and rhizospheric most probable number (MPN) at 60-day interval. The average biomass production and heights of C. speciosus in contaminated treatments were significantly (p < 0.05) lower compared to the unvegetated control. Plants grown in contaminated soil showed relatively reduced root surface area compared to the uncontaminated treatments. TPH degradation in planted fertilized, unplanted, and planted unfertilized pot was 63%, 0.8%, and 38%, respectively. However, compared to unvegetated treatments, TPH degradation was significantly higher (p < 0.05) in vegetated treatments. A comparison of fertilized and unfertilized soils showed that TPH accumulation in plant roots and shoots was relatively higher in fertilized soils. Hg degradation in soil was significantly (p < 0.05) more in planted treatment compared to unplanted treatments. The fertilized soil showed relatively more Hg degradation in soil and its accumulation in roots and shoots of plants in comparison to unfertilized soil. MPN in treatments with plants was significantly greater (p < 0.05) than without plants. The plant's ability to produce biomass, chlorophyll, break down crude oil, reduce Hg levels in soil, and accumulate TPH and Hg in roots and shoots of the plant all point to the possibility of using this plant to remove TPH and Hg from soil.

Gamma radiation-induced grafting of poly(butyl acrylate) onto ethylene vinyl acetate copolymer for improved crude oil flowability

Ethylene vinyl acetate (EVA) copolymers are widely employed as pour point depressants to enhance the flow properties of crude oil. However, EVA copolymers have limitations that necessitate their development. This work investigated the modification of EVA via gamma radiation-induced grafting of butyl acrylate (BuA) monomers and the evaluation of grafted EVA as a pour point depressant for crude oil. The successful grafting of poly(butyl acrylate) p(BuA) onto EVA was verified through grafting parameters, FTIR spectroscopy, and 1H NMR spectroscopy. Treating crude oil with 3000 ppm of (EVA)0kGy, (EVA)50kGy, and (1EVA:3BuA)50kGy yielded substantial reductions in pour point of 24, 21, and 21 °C, respectively. Also, rheological characterization demonstrated improving evidenced by a viscosity reduction of 76.20%, 67.70%, and 71.94% at 25 °C, and 83.16%, 74.98%, and 81.53% at 12 °C. At low dosages of 1000 ppm, the EVA-g-p(BuA) exhibited superior pour point reductions compared to unmodified EVA, highlighting the benefit of incorporating p(BuA) side chains. The grafted EVA copolymers with p(BuA) side chains showed excellent potential as crude oil flow improvers by promoting more effective adsorption and co-crystallization with paraffin wax molecules.

Oil droplet fouling on lesser sandeel (Ammodytes marinus) eggshells does not enhance the crude oil induced developmental toxicity

The oil industry's expansion and increased operational activity at older installations, along with their demolition, contribute to rising cumulative pollution and a heightened risk of accidental oil spills. The lesser sandeel (Ammodytes marinus) is a keystone prey species in the North Sea and coastal systems. Their eggs adhere to the seabed substrate making them particularly vulnerable to oil exposure during embryonic development. We evaluated the sensitivity of sandeel embryos to crude oil in a laboratory by exposing them to dispersed oil at concentrations of 0, 15, 50, and 150 µg/L oil between 2 and 16 days post-fertilization. We assessed water and tissue concentrations of THC and tPAH, cyp1a expression, lipid distribution in the eyes, head and trunk, and morphological and functional deformities. Oil droplets accumulated on the eggshell in all oil treatment groups, to which the embryo responded by a dose-dependent rise in cyp1a expression. The oil exposure led to only minor sublethal deformities in the upper jaw and otic vesicle. The findings suggest that lesser sandeel embryos are resilient to crude oil exposure. The lowest observed effect level documented in this study was 36 µg THC/L and 3 µg tPAH/L. The inclusion of these species-specific data in risk assessment models will enhance the precision of risk evaluations for the North Atlantic ecosystems.

Degradation and enhanced oil recovery potential of Alcanivorax borkumensis through production of bio-enzyme and bio-surfactant

Microbial enhanced oil recovery (EOR) has become the focus of oilfield research due to its low cost, environmental friendliness and sustainability. The degradation and EOR capacity of A. borkumensis through the production of bio-enzyme and bio-surfactant were first investigated in this study. The total protein concentration, acetylcholinesterase, esterase, lipase, alkane hydroxylase activity, surface tension, and emulsification index (EI) were determined at different culture times. The bio-surfactant was identified as glycolipid compound, and the yield was 2.6 ± 0.2 g/L. The nC12 and nC13 of crude oil were completely degraded, and more than 40.0 % of nC14-nC24 was degraded by by A. borkumensis. The results of the microscopic etching model displacement and core flooding experiments showed that emulsification was the main mechanism of EOR. A. borkumensis enhanced the recovery rate by 20.2 %. This study offers novel insights for the development of environmentally friendly and efficient oil fields.

Surface active dicationic ionic liquids as green oil spill dispersants

The utilization of chemical dispersants as a way of mitigating of oil spills in marine eco-system has been extensively documented worldwide. Hence, in this research we have successfully synthesized two amphiphilic asymmetric Dicaionic Ionic Liquids (DILs). The efficacy of these synthesized DILs as dispersants was assessed using the baffled flask test (BFT). The results indicated a dispersant effectiveness ranging from 47.98 % to 79.76 % for the dispersion of heavy crude oil across various temperature ranges (10-30 °C). These dispersant-to-oil ratios (DOR) were maintained at 3: 100 (V%), showcasing promising dispersant capabilities for mitigating heavy crude oil spills. Additionally, acute toxicity tests conducted on Nile tilapia and Oreochromis niloticus have demonstrated the relatively low toxicity of the IL-dispersants, with Lethal Concentration 50 (LC50) values exceeding 100 ppm after 96 h. This suggests a practically slight toxic effect on the tested fish. In summary, the newly developed IL-dispersants are considered to be conducive to environmentally benign oil spill remediation.

Modulatory effects of quercetin on histological changes, biochemical and oxidative stress of rat placenta induced by inhalation exposure to crude oil vapor

The inhalation exposure to crude oil vapor (COV) has been shown to have adverse effects on the placenta and fetal development. The modulatory effects of quercetin (QUE) as a natural phenolic compound with antioxidant properties are promising for the protection of placental structure. This study aimed to investigate the modulatory role of QUE in mitigating histopathological damage, oxidative stress, and biochemical alteration in the placenta of COV-exposed pregnant rats. Forty-eight pregnant rats were divided into eight groups (days 15 and 20) as follows: 1-2) Control groups, 3-4) COV groups, 5-6) COV+QUE groups, and 7-8) QUE-treated groups (50 mg/kg). The inhalation method was used to expose pregnant rats to COV, and QUE was administered orally. On the 15th and 20th days of gestation, placental tissue was analyzed using PAS and H&E staining and immunohistochemistry. The expression of the caspase-3 gene and oxidative stress biomarkers including TAC, CAT, MDA, GPx, and SOD were investigated in the placental tissue. The COV significantly decreased the weight, diameter, and thickness of the placenta as well as the thickness of the junctional zone and labyrinth and the number of trophoblast giant cells in 15- and 20-day-old placentas (P<0.05). Also, COV significantly increased placental expression of caspase-3 and the oxidative stress biomarkers (P<0.05). The administration of QUE along with exposure to COV reduced morphometric and histological alteration, oxidative stress, and caspase-3 expression (P<0.05). Our findings indicated that QUE in COV-exposed pregnant rats can prevent placental histopathological alternations by increasing the activity of the antioxidant system.

An experimental investigation and flow-system simulation about the influencing of silica-magnesium oxide nano-mixture on enhancing the rheological properties of Iraqi crude oil

This study aims to investigate the effects of introducing a 50/50 mixture of silica and magnesium oxide nanoparticles (SNP + MgONP) to the viscosity of Al-Ahdab crude oil (Iraq) at varied concentrations and temperatures. It is observed that the viscosity value drops from 38.49 to 7.8 cP. The highest degree of viscosity reduction is measured to be 56.91% at the maximum temperature of 50 °C and the greatest concentration of 0.4 wt% SM4. The Bingham model can be used to classify the behavior of the crude oil before the Nano-mixture is added. The liquid behavior grew closer to Newtonian behavior once the Nano-mixture was added. Along with a rise in plastic and effective viscosity values, the yield stress value decreases as the concentration of the Nano-mixture increases. The numerical data demonstrate that when the volume proportion of nanoparticles increases, the pressure distribution decreases. Furthermore, as the nanoparticle volume fraction increases, the drag decrease would also increase. SM4 obtains a maximum drag reduction of 53.17%. It is discovered that the sample SM4 has a maximum flow rate increase of 2.408%. Because they reduce the viscosity of crude oil, nanoparticles also reduce the friction factor ratio.

Toxicological Effects of Inhaled Crude Oil Vapor

PURPOSE OF REVIEW

The purpose of this review is to assess the toxicological consequences of crude oil vapor (COV) exposure in the workplace through evaluation of the most current epidemiologic and laboratory-based studies in the literature.

RECENT FINDINGS

Crude oil is a naturally occuring mixture of hydrocarbon deposits, inorganic and organic chemical compounds. Workers engaged in upstream processes of oil extraction are exposed to a number of risks and hazards, including getting crude oil on their skin or inhaling crude oil vapor. There have been several reports of workers who died as a result of inhalation of high levels of COV released upon opening thief hatches atop oil storage tanks. Although many investigations into the toxicity of specific hydrocarbons following inhalation during downstream oil processing have been conducted, there is a paucity of information on the potential toxicity of COV exposure itself. This review assesses current knowledge of the toxicological consequences of exposures to COV in the workplace.

Nanomagnetic Cyclodextrin decorated with ionic liquid as green and reversible Demulsifier for breaking of crude oil emulsions

Application of the chemical demulsifiers is the best choice for breaking the water in crude oil (W/O) emulsions in the petroleum industry. Here, novel, environmentally friendly, efficient, and easily reusable Fe3O4 nanomagnetic compounds based on imidazolium-decorated cyclodextrin were successfully synthesized and applied to demulsify the water in crude oil (W/O) emulsions. At first, Fe3O4 nanoparticles were decorated with β-cyclodextrin (β-CD) to prepare Fe3O4@β-CD@IL magnetic nanoparticles. Then, imidazole (Im) was separately reacted with 1-bromohexane and 1-bromodecane to prepare [Im-C6][Br] and [Im-C10][Br] ionic liquids, respectively. The prepared imidazolium-based ionic liquids were reacted with N-propyltriethoxysilane to synthesize [ImSi-C6][Br] and [ImSi-C10][Br]. Finally, [ImSi-Cn][Br] was immobilized on Fe3O4@β-CD to obtain nanomagnetic demulsifiers. Structure of the synthesized compounds was confirmed using different methods such as FT-IR, NMR, and elemental analysis. TGA, VSM, and FESEM methods were used to investigate the thermal stability, magnetic properties, and the morphology, respectively. Fe3O4@βCD and Fe3O4@βCD@[ImSi-C10][Br] nanoparticles respectively showed the particle size in the range of 40-70 nm and 50-80 nm. After grafting the imidazolium-based ionic liquid on the surface of support, the magnetization number reduced from 25.6 emu/g for Fe3O4@β-CD to 24.9 emu/g for Fe3O4@β-CD@[ImSi-C10][Br]. Synthesized material employed to break the (10:90 and 30:70 Vol%) W/O emulsions at the concentration range of 1000-5000 ppm. The maximum demulsification efficiency (DE%) of 92 % was obtained using a Fe3O4@β-CD@[ImSi-C10][Br] at 5000 ppm for (30:70 Vol%) W/O emulsion within 24 h. Interfacial tension (IFT) values decreased with increasing the DE%. The Fe3O4@βCD@[ImSi-C10][Br] demulsifier was reused five times with acceptable yields. The cooperation of imidazolium and β-CD in the green nanomagnetic demulsifiers led to the efficient demulsification of the W/O emulsions. The preparation of different ionic liquids or changing the counter anions are our potential future directions for this research. Demulsification at high demulsifier concentration can be considered a limitation of the nanomagnetic cyclodextrin decorated with ionic liquid. But due to the low amount of ionic liquid immobilized in the synthesized demulsifier, the cost of the final demulsifier is lower that other demulsifiers with full ionic liquid backbones, which increases its potential for industrial applications.

Unlocking bioremediation potential for site restoration: A comprehensive approach for crude oil degradation in agricultural soil and phytotoxicity assessment

Crude oil contamination has inflicted severe damage to soil ecosystems, necessitating effective remediation strategies. This study aimed to compare the efficacy of four different techniques (biostimulation, bioaugmentation, bioaugmentation + biostimulation, and natural attenuation) for remediating agricultural soil contaminated with crude oil using soil microcosms. A consortium of previously characterized bacteria Xanthomonas boreopolis, Microbacterium schleiferi, Pseudomonas aeruginosa, and Bacillus velezensis was constructed for bioaugmentation. The microbial count for the constructed consortium was recorded as 2.04 ± 0.11 × 108 CFU/g on 60 d in augmented and stimulated soil samples revealing their potential to thrive in chemically contaminated-stress conditions. The microbial consortium through bioaugmentation + biostimulation approach resulted in 79 ± 0.92% degradation of the total polyaromatic hydrocarbons (2 and 3 rings ∼ 74%, 4 and 5 rings ∼ 83% loss) whereas, 91 ± 0.56% degradation of total aliphatic hydrocarbons (C8-C16 ∼ 90%, C18-C28 ∼ 92%, C30 to C40 ∼ 88% loss) was observed in 60 d. Further, after 60 d of microcosm treatment, the treated soil samples were used for phytotoxicity assessment using wheat (Triticum aestivum), black chickpea (Cicer arietinum), and mustard (Brassica juncea). The germination rates for wheat (90%), black chickpea (100%), and mustard (100%) were observed in 7 d with improved shoot-root length and biomass in both bioaugmentation and biostimulation approaches. This study projects a comprehensive approach integrating bacterial consortium and nutrient augmentation strategies and underscores the vital role of innovative environmental management practices in fostering sustainable remediation of oil-contaminated soil ecosystems. The formulated bacterial consortium with a nutrient augmentation strategy can be utilized to restore agricultural lands towards reduced phytotoxicity and improved plant growth.

In vitro assessment of crude oil degradation by Acinetobacter junii and Alcanivorax xenomutans isolated from the coast of Ghana

This study was aimed at using in vitro microcosm experiments to assess crude oil degradation efficiency of Acinetobacter junii and Alcanivorax xenomutans isolated along Ghana's coast. Uncontaminated seawater from selected locations along the coast was used to isolate bacterial species by employing enrichment culture procedures with crude oil as the only carbon source. The isolates were identified by means of the extended direct colony transfer method of the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy (MALDI-TOF MS), as Acinetobacter junii, and Alcanivorax xenomutans. Remediation tests showed that Acinetobacter junii yielded degradation efficiencies of 27.59 %, 41.38 % and 57.47 %. Whereas efficiencies of 21.14 %, 32.18 % and 43.68 % were recorded by Alcanivorax xenomutans representing 15, 30 and 45 days respectively. Consortia of Acinetobacter junii, and Alcanivorax xenomutans also yielded 32.18 %, 48.28 % and 62.07 % for the selected days respectively. Phylogenetic characterization using ClustalW and BLAST of sequences generated from the Oxford Nanopore Sequencing technique, showed that the Ghanaian isolates clustered with Alcanivorax xenomutans and Acinetobacter junii species respectively. An analysis of the sequenced data for the 1394-bp portion of the 16S rRNA gene of the isolates revealed >99 % sequence identity with the isolates present on the GenBank database. The isolates of closest identity were Alcanivorax xenomutans and Acinetobacter junii with accession numbers, NR_133958.1 and KJ147060.1 respectively. Acinetobacter junii and Alcanivorax xenomutans isolated from Ghana's coast under pristine seawater conditions have therefore demonstrated their capacity to be used for the remediation of crude oil spills.

Effects of petrogenic pollutants on North Atlantic and Arctic Calanus copepods: From molecular mechanisms to population impacts

Oil and gas industries in the Northern Atlantic Ocean have gradually moved closer to the Arctic areas, a process expected to be further facilitated by sea ice withdrawal caused by global warming. Copepods of the genus Calanus hold a key position in these cold-water food webs, providing an important energetic link between primary production and higher trophic levels. Due to their ecological importance, there is a concern about how accidental oil spills and produced water discharges may impact cold-water copepods. In this review, we summarize the current knowledge of the toxicity of petroleum on North Atlantic and Arctic Calanus copepods. We also review how recent development of high-quality transcriptomes from RNA-sequencing of copepods have identified genes regulating key biological processes, like molting, diapause and reproduction in Calanus copepods, to suggest linkages between exposure, molecular mechanisms and effects on higher levels of biological organization. We found that the available ecotoxicity threshold data for these copepods provide valuable information about their sensitivity to acute petrogenic exposures; however, there is still insufficient knowledge regarding underlying mechanisms of toxicity and the potential for long-term implications of relevance for copepod ecology and phenology. Copepod transcriptomics has expanded our understanding of how key biological processes are regulated in cold-water copepods. These advances can improve our understanding of how pollutants affect biological processes, and thus provide the basis for new knowledge frameworks spanning the effect continuum from molecular initiating events to adverse effects of regulatory relevance. Such efforts, guided by concepts such as adverse outcome pathways (AOPs), enable standardized and transparent characterization and evaluation of knowledge and identifies research gaps and priorities. This review suggests enhancing mechanistic understanding of exposure-effect relationships to better understand and link biomarker responses to adverse effects to improve risk assessments assessing ecological effects of pollutant mixtures, like crude oil, in Arctic areas.

Comparison of two field systems for determination of crude oil biodegradation in cold seawater

Marine oil spills have devastating environmental impacts and extrapolation of experimental fate and impact data from the lab to the field remains challenging due to the lack of comparable field data. In this work we compared two field systems used to study in situ oil depletion with emphasis on biodegradation and associated microbial communities. The systems were based on (i) oil impregnated clay beads and (ii) hydrophobic Fluortex adsorbents coated with thin oil films. The bacterial communities associated with the two systems displayed similar compositions of dominant bacterial taxa. Initial abundances of Oceanospirillales were observed in both systems with later emergences of Flavobacteriales, Alteromonadales and Rhodobacterales. Depletion of oil compounds was significantly faster in the Fluortex system and most likely related to the greater bioavailability of oil compounds as compared to the clay bead system.

Convenient high resolution mass spectrometry characterization of aromatic sulfur-containing petroleum components following by preliminary S-alkylation with aliphatic alcohols

This paper describes rather suitable and variable preliminary derivatization strategy that may precede the molecular level characterization of sulfur-containing compounds of a particularly aromatic nature by high-resolution MALDI and ESI mass spectrometry. We demonstrated for the first time that free aliphatic alcohols (primary 1-alkanols C3-C20) in the presence of triflic acid provide easy S-alkylation of not only saturated sulfides but also most typical aromatic sulfur-containing compounds (benzothiophene, dibenzothiophene and their homologues) widely distributed and frequently analyzed in oil. The reaction proceeds quantitatively at rather mild conditions and gives rise to corresponding S-alkyl sulfonium salts the cation moieties of which can be detected using MALDI and ESI mass spectrometry with excellent signal/noise (S/N) ratios; the response ratios for target ions being quite close for both methods. Collision-induced dissociation (CID) of S-alkylsulfonium cations proceeds only by the elimination of entire S-alkyl group yielding protonated molecule of the analyte. This process can be useful for a reliable determination of target aromatic heterocyclic compounds in complex mixtures. The applicability of the method is illustrated by the analysis of deasphalted medium petroleum sample. The proposed derivatization principle is considered to be highly applicable as an alternative approach to routine characterization and sensitive determination of most typical sulfur-containing compounds and particularly of aromatic S-heterocycles in crude oils by soft-ionization mass spectrometry methods.

Assessment of asphaltene and resin fractions in crude oil using laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL)

Crude oil is one of the most significant petrogenic sources of polycyclic aromatic compounds (PACs). These substances play an essential role in the pollution of the marine environment. Therefore, the rapid identification of this pollutant source and its fractions is vital. For this purpose, a fast and on-site method of laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL) is proposed here using solvent densitometry. Three optical parameters of the self-quenching (K), the extinction (α), and the peak concentration (Cp) are experimentally extracted from MBL graphs. Note that the parameters above are known to be unique characteristics of various crude oils. The corresponding compounds are generally classified into saturate, aromatic, resin, and asphaltene fractions, abbreviated as SARA. Differentiation among these fractions is achieved using the LIFS-MBL method by selecting the optimal excitation wavelength at 405 nm. This line effectively rules out the light aromatic rings and focuses on heavy fractions. The correlation of optical parameters with heavy oil fractions is verified according to analysis of variance. Statistical relations are proposed to calculate crude oil fractions values. The values of light fractions including saturate and aromatic components can also be determined by the heavy fractions. In this method, the test time is notably reduced from four days using the standard methods to less than half an hour according to the presented LIFS-MBL technique.

RNA-sequencing analysis reveals the co-biodegradation performance of crude oil by marine Chlorella vulgaris under norfloxacin stress

In this study, the microalgal growth and crude oil (CRO) biodegradation by marine Chlorella vulgaris (C. vulgaris) were assessed under norfloxacin (NFX) stress. The presence of NFX negatively affected the bio-removal of CRO within 5 days, as the NFX concentration increased from 100 to 1600 μg/L, due to its toxicity as an antibiotic. However, its negative impact on the final degradation capabilities of C. vulgaris was less significant (P-value <0.05). After 9 days of cultivation, CRO bio-removal efficiencies still exceeded 90 %, while NFX bio-removal efficiencies maintained over 47 %. RNA-seq analysis revealed that the degradation of CRO and NFX was attributed to the combined action of functional genes involved in scavenging reactive oxygen species. The production of pigments and the bio-removal performance of C. vulgaris in CRO, NFX, and CRO & NFX coexistence media were consistent with the changes in the number of differentially expressed genes in these samples.

Resource utilization of expired progesterone medicines as flow improver for waxy crude oils

At present, the treatment of expired medicines mainly involves burning, which means waste of resources and carbon dioxide emissions, and it does not comply with the concept of resource recycling. In this study, in order to explore the resource utilization pathways of expired medicines, progesterone drugs were evaluated as crude oil flow improvers as an example. The results shows that progesterone injection (PI) and progesterone capsule (PC) both act as viscosity reducer and pour point depressant in different crude oil, and 500 ppm PI and 300 ppm PC are the best dosage respectively. 500 ppm PI can reduce the viscosity of HN oil sample by 60.40%, and depress the pour point by 8.5 °C. 300 ppm PC can reduce the viscosity of HN oil by 54.7%, and depress the pour point by 10.9 °C. Furthermore, through DSC and wax crystal morphology analysis, the possible mechanism of this expired medicine as crude oil flow improver was further discussed. Finally, considering the costs of concentration, transportation, treatment, processing and other links, the possible cost of crude oil flow improver was summed up, and its market feasibility was analyzed. This study provides a reference case for the resource utilization of expired medicines.

Do distributions of diamondoid hydrocarbons accumulated in oil-contaminated fish tissues help to identify the sources of oil?

Identifying the sources of environmental oil contamination can be challenging, especially for oil in motile organisms such as fish. Lipophilic hydrocarbons from oil can bioaccumulate in fish adipose tissue and potentially provide a forensic "fingerprint" of the original oil. Herein, diamondoid hydrocarbon distributions were employed to provide such fingerprints. Indices produced from diamondoids were used to compare extracts from fish adipose tissues and the crude and fuel oils to which the fish were exposed under laboratory conditions. A suite of 20 diamondoids was found to have bioaccumulated in the dietary-exposed fish. Cross-plots of indices between fish and exposure oils were close to the ideal 1:1 relationship. Comparisons with diamondoid distributions of non-exposure oils produced overall, but not exclusively, weaker correlations. Linear Discriminatory Analysis on a combined set of 15 diamondoid and bicyclane molecular ratios was able to identify the exposure oils, so a use of both compound classes is preferable.

Theoretical investigation of asphaltene molecules in crude oil viscoelasticity enhancement

Understanding the mechanisms of viscosity enhancement in crude oil phases is crucial for optimizing extraction and transportation processes. The enhanced viscosity mechanism of crude oil phase can be attributed to the intricate intermolecular interactions between asphaltene molecules. However, the molecular mechanism of the viscosification of asphaltene molecules in crude oil is not yet to be fully understood. In this work, molecular dynamics simulations were employed to investigate the dynamic behavior and viscosification mechanism of asphaltene molecules in complex oil phases. Research suggests that the neutral surface of asphaltenes features abundant positive and negative electrostatic potential regions, facilitating complementary pairing between these areas. This significantly augments electrostatic interactions among asphaltene molecules. Besides, the expansive nonpolar expanse on the normal asphaltene surface facilitates interactions between asphaltenes and crude oil molecules. This leads the crude oil viscosity of the system containing normal asphaltene is higher than that of the system containing acidic asphaltene under the same mass fraction (382 μ Pa·s for AAsp and 416 μ Pa·s for NAsp). This work provides insight into the viscosity enhancement mechanisms in crude oil phases and is helpful in improving the efficiency of crude oil extraction and transportation.

Effect of the bare and functionalized single-wall carbon nanotubes on inhibition of asphaltene molecules aggregation: A molecular dynamic simulation

A comprehensive study has been carried out by utilizing the molecular dynamics technique in order to investigate the behavior of the N-(1-hexylheptyl)-N'-(2-phenylpropanoicacid)-perylene-3,4,9,10-tetracarboxylicbisimide (PAP) molecules in the n-heptane/toluene solution as well as the role of the bare and functionalized single-wall carbon nanotubes (SWCNTs) with the carboxyl groups (-COOH) on the aggregation of PAP molecules. It was found that the CNTs benefit two mechanism of steric hindrance and adsorbing the PAP molecules to suppress the affinity of PAP molecules to association. The results ascertain that the constant amount of the carboxyl groups acts more efficiently in restricting the growth of aggregate size if they are distributed on the surface of a larger CNT. Both of the increased nonbonding interactions between the functionalized CNTs and the PAP molecules, and the number of formed hydrogen bonds between them clearly proved the efficiency of the -COOH groups in improving the stability of PAP molecules. The strength of the adsorption free energies revealed that the PAP molecule shows more tendency to be adsorbed on the surface of CNT modified with carboxyl groups. Increasing the dosage of the -COOH groups on the surface of the CNTs with constant dimension causes an increment in the PAP molecules' solvent accessible surface area (SASA) value, indicating enhanced stability of the PAP molecules. Finally, the results would facilitate future studies on manipulating the asphaltene precipitation in the oil industry.

Ecological changes in subtidal macrobenthic communities of the Taean coast following the Hebei Spirit oil spill: A 10-year longitudinal study

We examined long-term response (2008-2017) of the macrobenthos to the Hebei Spirit oil spill that occurred around the Taean coast, Korea, in December 2007. Oil concentrations were below the Korea/US environmental standards as of January 2008. Organic matter, chlorophyll-a, and zooplankton abundance dominated by Noctiluca scintillans were higher after the spill. Macrobenthic diversity recovered to pre-incident (2007) level in 2011. Biomass exceeded that level in 2011 and the increase prolonged for 5 years. Cross-correlation and regression analyses showed that chlorophyll-a at year t and zooplankton abundance at t-2 had a significant relationship with macrobenthic biomass at t (p < 0.05 for both), suggesting the transfer of increased organic matter (transformed from crude oil within the pelagic ecosystem) into the benthic ecosystem. Coastal wetlands around the incident area, vulnerable to oil pollution and slowly remobilizing accumulated oil, seemed to affect pelagic ecosystem processes and the unexpectedly increased and sustained biomass.

Unravelling the dynamics of human development and economic growth on crude oil production based on ARDL and NARDL models

This paper estimates and establishes the causality between the Human Development Index (HDI), Gross Domestic Product (GDP), inflation and CO2 emissions on crude oil production (COP) in Cameroon from 1977 to 2019. To do so, the Augmented Dicky-Fuller and Zivot-Andrews stationarity tests, ARDL and NARDL modelling, as well as Toda-Yamamoto causality test are performed. Unlike previous studies on COP, this study incorporates the asymmetric impact (NARDL). The results indicate that CO2 emissions and GDP have a negative impact on COP in the long-run, while HDI and inflation have a positive impact in the short-run. GDP and HDI have a non-linear impact in the short run, while in the long-run inflation and CO2 emissions have a non-linear impact on COP. From these results, it is interesting to note that, in order to allow future generations to benefit from the oil windfall. The diversification of the Cameroonian economy, the control of inflation and the use of less polluting crude oil extraction technologies must be imperative.•A step-by-step procedure of the ARDL, NARDL and causality test is provided.•The multiplier effects of GDP, HDI, inflation and CO2 emissions on COP are simulated.•The impact of GDP and HDI on COP is non-linear.

Potential of some microbial isolates on diesel hydrocarbons removal, bio surfactant production and biofilm formation

Potential of Arthrobacter citreus B27Pet, Bacillus thuringiensis B48Pet and Candida catnulata to produce biosurfactant using four different carbon sources (naphthalene, hexadecane, diesel and petroleum crude oil) was investigated. Removal of petroleum crude oil from aqueous culture and degradation of diesel were also determined using single and mixed culture of strains. The biofilm existence in single and mixed culture of strains was considered using naphthalene, hexadecane and diesel in culture medium. Cell surface hydrophobicity of A. citreus was higher than other isolates which also showed maximum surface tension reduction and emulsification index. As a whole, remarkable biosurfactant production occurred using petroleum crude oil as a carbon source in medium. A. citreus was found to be more robust than other tested strains in removal efficiency of crude oil due to its biosurfactant production capability. Statistically significant positive correlation was observed between biofilm existence and surface tension using diesel and hexadecane as carbon source. Overall diesel biodegradation efficiency by the mix culture of three applied strains was about 75% within a short period of time (10 days) which was accompanied with high biofilm production.

Heavy metals contamination of seafood from the crude oil-impacted Niger Delta Region of Nigeria: A systematic review and meta-analysis

This study aims at computing the pooled mean estimate (PME) and health risks of heavy metals in seafood obtained from the Niger Delta Region of Nigeria (NDRN), using data from existing literatures. Pubmed, Scopus and Google Scholar were searched to retrieve articles that investigated the heavy metal contents of edible seafood from the NDRN. Search hits were screened against predetermined criteria following which relevant data were extracted from eligible articles. The PME for each metal was computed by performing a maximum likelihood random effect model meta-analysis using the R Studio Software. Outcome from the meta-analysis involving 58 studies and a total of 2983 seafood samples revealed the following PMEs (mg/kg dry wt seafood) for the investigated heavy metals: As (0.777), Cd (0.985), Co (4.039), Cr (2.26), Cu (11.45), Fe (143.39), Hg (0.0058), Mn (13.56), Ni (5.26), Pb (4.35), and Zn (29.32). The health risk assessment suggests that seafood from this region poses considerable carcinogenic and non-carcinogenic risks to human consumers. Our finding calls for urgent actions aimed at identifying and eliminating point sources of heavy metals pollution of the NDRN marine environment. Inhabitants of NDRN are encouraged to reduce seafood consumption while diversifying their protein sources to include non-seafood options.

on biodegradation efficiency of crude oil and anthracene

Biosurfactants are surface active molecules generated by various microorganisms, including bacteria, actinobacteria, algae, and fungi. In this study, bacterial strains are isolated from soil contaminated with used motor oil and examined for potential biosurfactant production. A minimum salt medium (MSM), with crude oil as the only carbon source, is used to isolate potential biosurfactant-producing bacterial strains. About 23 strains are isolated, and all are subjected to the primary screening methods for biosurfactant production. Based on the emulsification index, oil displacement, and drop collapse screening methods, two isolates with potential biosurfactant-producing ability are selected for further studies. The synthesis of biosurfactants, crude oil and anthracene biodegradation is carried out with strains DTS1 and DTS2. Both strains show significant outcomes in crude oil degradation. In addition, both strains can utilize anthracene as the sole carbon source. During the degradation course, changes in the growth conditions are continuously monitored by measuring turbidity and pH. In this degradation study, the biosurfactant production aptitude of the isolated strains plays an essential role in increasing the bioavailability of hydrophobic hydrocarbons. These strains are identified down to the molecular level by employing 16S rRNA gene sequencing, and the acquired sequences are submitted to get the accession numbers. These prospective strains can be utilized to remediate hydrocarbon-contaminated environments.

Bio-sorptive remediation of crude oil polluted sea water using plantain (Musa parasidiaca) leaves as bio-based sorbent: Parametric optimization by Taguchi technique, equilibrium isotherm and kinetic modelling studies

This study investigated the potential of employing plantain leaves as a natural bio-based sorbent for crude oil spill polluted seawater remediation. Type L9(34) Taguchi orthogonal array technique was used to evaluate the effect of four independent bio-sorption factors at three different levels (crude oil initial concentration (X1 7.8, 11.5 and 15.6 g/L), seawater-crude oil temperature (X2 25, 35 and 45 °C), bio-sorbent dosage (X3 1, 2 and 3 g) and bio-sorbent particle size (X4 1.18, 2.36 and 4.72 mm) on two response indices (bio-sorption efficiency (%) and bio-sorption capacity (g/g)). Taguchi optimization technique, numerical-desirability index function optimization technique and a proposed optimization method were utilized to determine the optimum bio-sorption factors needed for the optimum bio-sorption efficiency and bio-sorption capacity. The results demonstrated that the crude oil bio-sorption efficiency of the plantain leaves was significantly influenced by X1, X3 and X4 and the bio-sorption capacity was mainly influenced by X1 and X3. The optimum bio-sorption efficiency and the optimum bio-sorption capacity were 99.05 % and 12.82 g/g, respectively, obtained at optimum combination of factors and levels of X11 (7.8 g/L), X33 (3 g) and X41 (1.18 mm) for bio-sorption efficiency and X13 (15.6 g/L) X31 (1 g) for bio-sorption capacity. The Freundlich and Dubinin-Rudeshkevich isotherm models best explain the equilibrium bio-sorption data, while the pseudo-second order kinetic model best describes the bio-sorption kinetics. The bio-sorptive remediation mechanism followed dual mechanism of physical and chemical bio-sorption and the mass transfer controlled by film diffusion. The maximum bio-sorption capacity (K f ) was 14.0 gg-1.

Environmental impact of fouling for crude oil flow in preheat pipes according to oil blends

Crude oil fouling is a complex process caused by multiple mechanisms. This study examined fouling's environmental impact on a distillation unit's heating tubes and heat exchangers, proposing optimal pollution levels to reduce emissions and achieve sustainability goals. The study evaluated five crude oil blends in terms of API, sulphur, salt content, and other physical properties. Contaminated water was analyzed through biological and chemical means, while CO2, NOx, and SOx emissions were calculated from actual fuel and power consumption. Solid and sludge sediments were observed throughout all plate heat exchangers, consisting primarily of iron hydroxides and manganese oxides. Rationalizing energy use reduced the burden on the environment and fuel consumption by 7 %, with a 2 % reduction in energy needed to refine crude oil feeding units when fouling is removed after maintenance. By optimizing pollution levels and reducing energy consumption, the environmental impact of fouling can be mitigated.

Do implied volatilities of stock and commodity markets affect conventional & shariah indices differently? An evidence by OVX, GVZ and VIX

The current study aims to investigate how index returns of conventional and shariah indices of the USA, Europe, and Asia are affected by changes in oil prices, gold prices, VIX, gold-VIX, and oil-VIX. In our investigation, we used the S&P 500, S&P Europe 350, S&P Pan Asia, and their relevant shariah counterparts for the USA, Europe, and Asia. To examine how the explanatory factors affect the overall distribution of the explained variables, we used OLS and quantile regression. For the time frame prior to Covid-19, we discover that all volatility indices-OVX, GVZ, and VIX-influence returns of all indices simultaneously, and that all variables-aside from the spot price of oil-have a greater impact during the bear phase according to QR findings. Further, Volatility indices have a greater impact on volatility of index returns during the Covid-19 period. This is largely because the Covid-19 outbreak had a rapid impact on economies all around the world, and the only thing that affected financial markets consistently was high volatility. This is further supported by the findings of BEKK, which demonstrate that volatility extends across all markets and originates from commodities like gold, oil, gold-VIX, and VIX. Evidence for this can be seen in the fact that during the COVID-19 period, stock prices reacted more favorably to oil price volatility than to oil spot prices, which even went negative on April 20, 2020. Because of this, market stability can be promoted by reducing volatility through the prompt dissemination of crucial information, even while governments have little direct control over the prices of significant commodities like gold and crude oil.

Transcriptome analysis of a springtail, Folsomia candida, reveals energy constraint and oxidative stress during petroleum hydrocarbon exposure

Petroleum hydrocarbon (PHC) contamination in soil is ubiquitous and poses harmful consequences to many organisms. The toxicity of PHC-impacted soil is difficult to predict due to variations in mixture composition and the impacts of natural weathering processes. Hence, high-throughput methods to assess PHC-impacted soils is required to expedite land management decisions. Next-generation sequencing is a robust tool that allows researchers to investigate the effects of contaminants on the transcriptome of organisms and identify molecular biomarkers. In this study, the effects of PHCs on conventional endpoints (i.e., survival and reproduction) and gene expression rates of a model springtail species, Folsomia candida were investigated. Age-synchronized F. candida were exposed to ecologically-relevant concentrations of soils spiked with fresh crude oil to calculate the reproductive EC25 and EC50 values using conventional toxicity testing. Soils spiked to these concentrations were then used to evaluate effects on the F. candida transcriptome over a 7-day exposure period. RNA-seq analysis found 98 and 132 differentially expressed genes when compared to the control for the EC25 and EC50 treatment groups, respectively. The majority of up-regulated genes were related to xenobiotic biotransformation reactions and oxidative stress response, while down-regulated genes coded for carbohydrate and peptide metabolic processes. Promotion of the pentose phosphate pathway was also found. Results suggest that the decreased reproduction rates of F. candida exposed to PHCs is due to energy constraints caused by inhibition of carbohydrate metabolic processes and allocation of remaining energy to detoxify xenobiotics. These findings provide insights into the molecular effects in F. candida following exposure to crude oil for seven days and highlight their potential to be used as a high-throughput screening test for PHC-contaminated sites. Adverse molecular effects can be measured as early as 24 h following exposure, whereas conventional toxicity tests may require a minimum of four weeks.

Respiratory Health Effects of Pollution Due to Artisanal Crude-Oil Refining in Bayelsa, Nigeria

Purpose

Artisanal refining of crude oil has been associated with the manifestations of various health problems directly related to the release of particulate matter, including polycyclic aromatic hydrocarbons (PAHs), into the environment. This study thus assessed the respiratory health effects associated with being resident in areas where crude oil is artisanally refined in Bayelsa State.

Material and methods

This study utilized a comparative, cross-sectional design and was conducted in three communities in Bayelsa State. These included Sampou (a mildly exposed community), Nembe, and Gbarain (severely exposed communities). A sample population of 615 adults selected by multistage sampling completed the study instrument, which assessed data on their respiratory health. Environmental monitoring of the PAHs levels of the samples was done, and concentrations were determined using the gas chromatography/flame ionization detector (GC/FID). The Statistical Package for Social Sciences version 25 was used to conduct descriptive and inferential analyses.

Results

Findings revealed that the highest number of moderate to severe respiratory disease symptoms was experienced by respondents from Nembe 12 (41.4%), followed by those from Sampou 8 (27.6%), and then by those from Gbarain 9 (31.0%). Also, coughing that occurred mostly when lying down was found to be significantly prevalent among residents of Nembe [35 (47.9%); p-value: 0.016], among other symptoms. Respiratory disease symptoms were more likely to be found among females (p-value: 0.037), smokers (p-value: 0.002), and those having a low health risk perception related to PAHs exposure (p-value: 0.002).

Conclusion

Respondents from the three study sites had in the past 12 months experienced various respiratory disease symptoms, which could be directly related to their exposure to pollution from artisanal crude oil refining. Artisanal refining of crude oil should be continually dissuaded through unwavering enforcement of environmental health laws in order to further improve public and environmental health.

MXene/Graphene modified cellulose aerogel for photo-electro-assisted all-weather cleanup of high-viscous crude oil from spill

The frequent occurrence of oil spills has led to serious environmental pollution and ecological issues. Given the high-viscosity of crude oil, it is essential to develop sorbents with efficient viscosity reduction and sorption capacity in various environmental conditions. Herein, a superhydrophobic carboxymethyl cellulose (CMC) aerogel co-modified by MXene and graphene jointly (M-Mxene/Gr CA) with aligned channels structure was prepared. The aligned channels structure can effectively improve the longitudinal thermal conductivity and reduce the sorption resistance. Through the modification of MXene and graphene, the aerogel realized efficient photo/electro-thermal conversion, thus ensuring its adaption to various working environments. The rapid heat generation can significantly reduce the viscosity of crude oil, achieving rapid recovery. Under one sun illumination (1.0 kW/m2), the surface temperature of M-Mxene/Gr CA can reach 72.6 °C and its sorption capability for high-viscous crude oil reaches 18 g/g. Combining photo-thermal and electro-thermal (0.5 kW/m2 and 23 V), the average sorption rate of crude oil can reach 1.3 × 107 g m-3 s-1. Finally, we present a continuous sorption system to recover offshore oil spills under the assistance of a pump. This work provides a new option for tackling high-viscous offshore oil spills due to its environmental friendliness and fast sorption capacity.

immobilized beads for optimized biosurfactant production and degradation of crude oil

The widespread exploration and exploitation of crude oil has increased the prevalence of petroleum hydrocarbon pollution in the marine and coastal environment. Bioremediation of petroleum hydrocarbons using cell immobilization techniques is gaining increasing attention. In this study, the crude oil degradation performance of bacterial and fungal co-culture was optimized by entrapping both cells in sodium-alginate and polyvinyl alcohol composite beads. Results indicate that fungal cells remained active after entrapment and throughout the experiment, while bacterial cells were non-viable at the end of the experimental period in treatments with the bacterial-fungal ratio of 1:2. A remarkable decrease in surface tension from 72 mN/m to 36.51 mN/m was achieved in treatments with the bacterial-fungal ratio of 3:1. This resulted in a significant (P < 0.05) total petroleum hydrocarbon (TPH) removal rate of 89.4%, and the highest degradation of n-alkanes fractions (from 2129.01 mg/L to 118.53 mg/L), compared to the other treatments. Whereas PAHs removal was highest in treatments with the most fungal abundance (from 980.96 μg/L to 177.3 μg/L). Furthermore, enzymes analysis test revealed that catalase had the most effect on microbial degradation of the target substrate, while protease had no significant impact on the degradation process. High expression of almA and PAH-RHDa genes was achieved in the co-culture treatments, which correlated significantly (P < 0.05) with n-alkanes and PAHs removal, respectively. These results indicate that the application of immobilized bacterial and fungal cells in defined co-culture systems is an effective strategy for enhanced biodegradation of petroleum hydrocarbons in aqueous systems.

Biodegradation of saturate fraction of crude oil and production of signature carboxylic acids

Bacteria degrading large portion of saturated hydrocarbons are important for crude oil bioremediation. This study investigates Novosphingobium sp. S1, Gordonia amicalis S2 and Gordonia terrae S5 capability of degrading wide range of saturated hydrocarbons from Congo Bilondo crude oil and discusses the degradation pathway. A parallel analytical approach combining GC-MS and LC-HRMS enabled characterization of saturated hydrocarbons and comprehensive determination of carboxylic acid metabolites produced during biodegradation, respectively. Results showed that the three strains could efficiently degrade the n-alkanes (C10-C28) as well as methyl-substituted alkanes (C11-C26). The series of mono-, hydroxy- and dicarboxylic acids identified in this study confirmed the active biodegradation of the saturate fraction and suggest their degradation was via the bi-terminal oxidation pathway. This is the first study linking these bacterial species to bi-terminal oxidation of the saturated hydrocarbons. The study highlights the potential application of the bacterial strains in the bioremediation of crude oil contaminated sites. Additionally, while carboxylic acids is indicated as a suitable and valuable metabolic biomarker, its application is considered feasible and cost effective for rapid monitoring and evaluation of hydrocarbon biodegradation.

Degradation of crude oil-associated polycyclic aromatic hydrocarbons by marine-derived fungi

One of the major environmental concerns today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Crude oil is a complex mixture of hydrocarbons like alkanes, naphthene and polycyclic aromatic hydrocarbons (PAHs). PAHs are known to be highly toxic to humans and animals due to their carcinogenic and mutagenic effects. PAHs are environmentally recalcitrant due to their hydrophobicity which makes them difficult to degrade, thus making them persistent environmental contaminants. The mechanical and chemical methods in practice currently to remove hydrocarbon contaminants have limited effectiveness and are expensive. Bioremediation is a cost-effective technology for treating hydrocarbon-contaminated sites as it results in the complete mineralisation of the pollutant. This study demonstrates the degradation of crude oil and associated PAHs using ten fungal cultures isolated from the aquatic environment. The current study reported a 98.6% and 92.9% reduction in total PAHs in crude oil by Fusarium species, i.e. isolate NIOSN-T4 and NIOSN-T5, respectively. The fungal isolate, NIOSN-T4, identified as Fusarium equiseti, showed maximum PAH degradation efficiency of LMW PAHs 97.8%. NIOSN-M126, identified as Penicillium citrinum, exhibited a 100% removal of HMW PAHs. Microorganisms possess an untapped potential for various applications in biotechnology, and the current study demonstrated the potential of marine fungi for use in the bioremediation of xenobiotic hydrocarbons in the environment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03753-2.

On-line determination of the water cut and chlorine impurities in crude oil using a pulsed beam of fast neutrons

A neutron-based sensor has been developed able to measure the water cut and the chlorine content in crude oil. The sensor is based upon the use of a pulsed fast neutron source. Two different cases were studied. Case ''A'': chlorine detection with no water present and case ''B'': water cut measurements with no chlorine present. The minimum detection limits for case A and case B were found to be (62 ± 6) mg/L and (2 ± 2) vol%, respectively.

Determination of Cl and S in crude oil by ICP-OES after sample digestion by microwave-induced combustion in disposable vessels

A simple, fast and promising sample preparation method based on microwave-induced combustion in disposable vessels (MIC-DV) was developed for Cl and S determination in crude oil by inductively coupled plasma optical emission spectrometry (ICP-OES). The MIC-DV consists of a new approach of conventional microwave-induced combustion (MIC). For the combustion, crude oil was pipetted on a disk of filter paper and placed on a quartz holder, followed by the addition of igniter solution (40 μL of 10 mol L^-1 NH₄NO₃). The quartz holder was inserted into a commercial 50 mL disposable polypropylene vessel containing the absorbing solution, which was then inserted in an aluminium rotor. The combustion occurs under atmospheric pressure in a domestic microwave oven not compromising the operator's safety. The following parameters of combustion were evaluated: type, concentration and volume of absorbing solution, sample mass and the possibility of performing consecutive combustion cycles. Using MIC-DV, up to 10 mg of crude oil were efficiently digested, using 2.5 mL of ultrapure H₂O as absorbing solution. Moreover, up to 5 consecutive combustion cycles were possible without analyte losses, reaching a total sample mass of 50 mg. The MIC-DV method was validated according to Eurachem Guide recommendations. Results obtained for Cl and S by MIC-DV were in agreement with those obtained using conventional MIC, as well as those obtained for S in a certified reference material of crude oil (NIST 2721). Analyte spike recovery experiments were performed and recoveries at three concentration levels ranged from 99 to 101% for Cl and from 95 to 97% for S, indicating a good accuracy. The limit of quantification achieved by ICP-OES after MIC-DV were 73 and 50 μg g^-1 for Cl and S respectively, applying 5 consecutive combustion cycles.

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Prenatal exposure to crude oil vapor reduces differentiation potential of rat fetal mesenchymal stem cells by regulating ERK1/2 and PI3K signaling pathways: Protective effect of quercetin

It has been indicated that crude oil vapor (COV) induces tissue damage by several molecular mechanisms. Quercetin (QT) as an important component of food with antioxidant properties has a protective role against cell toxicity caused by many pollutants. However, data related to the adverse effects of crude oil vapor (COV) on stem cell fate and differentiation and the role of quercetin (QT) in protecting stem cells against the toxicity caused by these pollutants is very limited. This study aimed to explore the protective effect of QT against the adverse effects of COV on fetal mesenchymal stem cells (fMSCs) differentiation. Twenty-four pregnant Wistar rats were categorized into 4 groups including the control, COV, COV+QT, and QT. Rats were exposed to COV from gestational day (GD) 0-15 and received QT by gavage. The fMSCs were isolated from fetuses, and cell proliferation, differentiation potential, expression of osteogenesis and adipogenesis-related genes, and phosphorylation of PI3K and ERK1/2 signaling proteins were evaluated. The results showed that COV reduced the proliferation and differentiation of fMSCs through the activation of PI3K and ERK1/2 signaling pathways. Also, COV significantly decreased the expression of osteonectin, ALP, BMP-6, Runx-2, PPARγ, and CREBBP genes in differentiated cells. QT treatment increased the proliferation and differentiation of fMSCs in COV-exposed rats. In conclusion, our findings suggest that prenatal exposure to COV impaired fMSCs differentiation and QT reduced the adverse effects of COV by regulating ERK1/2 and PI3K signaling pathways.

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.

Highlighting the potential for crude oil bioremediation of locally isolated Cunninghamella echinulata and Mucor circinelloides

The current investigation was carried out to assess the potential of fungi isolated from polluted soil samples in Al Jubail, Saudi Arabia, to degrade crude oil. In a minimal salt medium with 1% crude oil as the carbon source, the growth potential of various fungal isolates was examined. Among twelve fungal isolates, YS-6 and YS-10, identified as Cunninghamella echinulata and Mucor circinelloides based on multiple sequence comparisons and phylogenetic analyses, were selected as having superior crude oil degrading abilities. To the best of our knowledge, the isolated species have never been detected in polluted soil samples in the eastern province of Saudi Arabia. YS-6 and YS-10 have shown their capacity to metabolize crude oil by removing 59.7 and 78.1% of crude oil, respectively. Interestingly, they succeeded in reducing the surface tension to 41.2 and 35.9 mN/m, respectively. Moreover, the emulsification activity and hydrophobicity were determined to be 36.7, 44.9, 35.9, and 53.4%, respectively. The recovery assays included zinc sulfate, ammonium sulfate, acid precipitation, and solvent extraction techniques. All these approaches showed that the amount of biosurfactants correlates to the tested hydrocarbons. Furthermore, the enzyme activity of these two isolates generated significantly more laccase (Lac) than manganese peroxidase (MnP) and lignin peroxidase (LiP), as compared to the control. In conclusion, our study highlights new perspectives on the fungal resources found in persistently polluted terrestrial ecosystems. This knowledge will be useful for bioremediation, safe disposal of petroleum-oil contamination, and other industrial uses.

Dynamic risk connectedness of crude oil price and sustainable investment in the United States: evidence from DCC-GARCH

Sustainable investment is widely regarded as an important market-based approach to achieving inclusive green growth. To achieve the inclusive green growth objective, companies providing sustainable products must be profitable enough to attract private capital. Oil price changes can however affect the profitability of such companies. This study assesses volatility transmission between crude oil prices and sustainable investment in the USA. Using the dynamic conditional correlation-generalized autoregressive conditional heteroskedasticity (DCC-GARCH) method, daily data from September 28, 2012, to October 19, 2022, is analyzed. There are several key findings from this analysis. The risk connectedness of crude oil and sustainable investment is found to vary with time. Results further show that the risk connectedness increases in periods of important economic and geopolitical events. The greatest risk connectedness of crude oil and sustainable investment is observed during the outbreak of coronavirus disease (COVID-19). Moreover, the result shows that crude oil is the main risk transmitter, whereas, both the energy efficiency and pollution mitigation indices (i.e., sustainable investment) are risk receivers, and crude oil is constantly dominating sustainable investment. The study findings provide valuable insights for investors and policymakers alike.

Microbial communities succession post to polymer flood demonstrate a role in enhanced oil recovery

The role of indigenous microbial communities in residual oil extraction following a recovery process is not well understood. This study investigated the dynamics of resident microbial communities in oil-field simulating sand pack bioreactors after the polymer flooding stage resumed with waterflooding and explored their contribution to the oil extraction process. The microbial community succession was studied through high-throughput sequencing of 16S rRNA genes. The results revealed alternating dominance of minority populations, including Dietzia sps., Acinetobacter sps., Soehngenia sps., and Paracoccus sps., in each bioreactor following the flooding process. Additionally, the post-polymer waterflooding stage led to higher oil recovery, with hydroxyethylcellulose, tragacanth gum, and partially hydrolyzed polyacrylamide polymer-treated bioreactors yielding additional recovery of 4.36%, 5.39%, and 3.90% residual oil in place, respectively. The dominant microbial communities were previously reported to synthesize biosurfactants and emulsifiers, as well as degrade and utilize hydrocarbons, indicating their role in aiding the recovery process. However, the correlation analysis of the most abundant taxa showed that some species were more positively correlated with the oil recovery process, while others acted as competitors for the carbon source. The study also found that higher biomass favored the plugging of high permeability zones in the reservoir, facilitating the dislodging of crude oil in new channels. In conclusion, this study suggests that microbial populations significantly shift upon polymer treatment and contribute synergistically to the oil recovery process depending on the characteristics of the polymers injected. KEY POINTS: • Post-polymer flooded microbial ecology shows unique indigenous microbial consortia. • Injected polymers are observed to act as enrichment substrates by resident communities. • The first study to show successive oil recovery stage post-polymer flood without external influence.

Investigating the crude oil biodegradation performance in membrane bioreactor by using a consortium of symbiotic bacteria

Crude oil pollution is one of the most serious environmental issues today, and the clean-up procedure is perhaps the most difficult. Within one to three weeks, the vast majority of oil bacteria may degrade approximately 60% of the crude oil, leaving approximately 40% intact. The by-product metabolites produced during the breakdown of oil are essentially organic molecules in nature. These metabolites inhibit its enzymes, preventing the oil bacteria from further degrading the oil. By combining a variety of different oils with heterotrophic bacteria in a bioreactor, the rate of crude oil biodegradation was accelerated. In this study, two strains of oil-resistant, heterotrophic bacteria (OG1 and OG2-Erythrobacter citreus) and a bacterium that uses hydrocarbons (AR3-Pseudomonas pseudoalcaligenes) were used. Gas chromatography-mass spectroscopy was used to investigate the effectiveness of this consortium of symbiotic bacteria in the biodegradation of crude oil. According to gravimetric and gas chromatography analyses, the consortium bacteria digested 69.6% of the crude oil in the bioreactor, while the AR3 single strain was only able to destroy 61.9% of it. Under the same experimental conditions, consortium bacteria degraded approximately 84550.851 ppb (96.3%) of 16 aliphatic hydrocarbons and 9333.178 ppb (70.5%) of 16 aromatic hydrocarbons in the bioreactor. It may be inferred that the novel consortium of symbiotic bacteria accelerated the biodegradation process and had great potential for use in increasing the bioremediation of hydrocarbon-contaminated locations.

The loss of crude oil droplets by filter feeders and the role of surfactants

Various methods of oil spill remediation exist, e.g., floating booms, controlled burning and the release of chemical surfactants. These surfactants facilitate the breakup of the slick into micron-sized droplets. Here, we studied the impact such a surfactant has on the size distribution of oil droplets in the water column and in the gut of the filter feeder Daphnia magna. We also studied the effect of surfactants on detachment conditions of chemically and mechanically dispersed oil (respectively MDO and CDO) droplets from capture fibers. Our results show that including solubilized dioctyl sulfosuccinate sodium salt in the mixing of the emulsion produces smaller droplets and a narrower size distribution in the water. In the gut, the size of ingested droplets does not change whether the oil is mixed mechanically or chemically. Also, surfactant coated droplets detach at a lower velocity than mechanically dispersed droplet because of their lower oil/water interfacial tension.

A step closer to real practice: Integrated tandem photocatalysis-biofilm process towards degradation of crude oil

Intimately coupled photocatalysis and biodegradation (ICPB) systems represent a promising wastewater treatment technology. The implementation of ICPB systems for oil spill treatment is a pressing concern. In this study, we developed an ICPB system comprising BiOBr/modified g-C₃N₄ (M-CN) and biofilms for the treatment of oil spills. The results demonstrate that the ICPB system achieved the rapid degradation of crude oil, outperforming the single photocatalysis and biodegradation methods by degrading 89.08 ± 5.36% within 48 h. The combination of BiOBr and M-CN formed a Z-scheme heterojunction structure, enhancing the redox capacity. The interaction between the holes (h⁺) and the negative charge on the biofilm surface promoted the separation of electrons (e^-) and h⁺, thereby accelerating the degradation process of crude oil. Moreover, ICPB system maintained an excellent degradation ratio after three cycles and its biofilms progressively adapted to the adverse effects of crude oil and light. The microbial community structure remained stable throughout the degradation of crude oil, with Acinetobacter and Sphingobium identified as the dominant genera in biofilms. The proliferation of the Acinetobacter genus appeared to be the main factor contributing to the promotion of crude oil degradation. Our work demonstrates that the integrated tandem strategies perhaps represent a feasible pathway toward practical crude oil degradation.

Optimization of water/oil emulsion preparation: Impact of time, speed, and homogenizer type on droplet size and dehydration efficiency

Due to their distinctive physical and chemical properties, emulsions are widely used in various industries such as pharmaceuticals, cosmetics, food, energy, and oil. Emulsion preparation differs from one application to another due to the effect of multiple parameters that can control droplet size and stability. However, there is a lack of fundamental understanding of the effect of emulsion preparation on its stability and performance. The emulsion preparation protocols can directly affect dehydration efficiency and stability. Herein, we report the influence of preparation conditions on the properties of the formed emulsions; we investigated the effect of mixing time, speed, and mixer type on the synthetic crude oil emulsion's droplet size and dehydration efficiency.

Biomarker responses in mussels (Mytilus trossulus) from the Baltic Sea exposed to water-accommodated fraction of crude oil and a dispersant at different salinities

Oil spills pose significant environmental risks, particularly in cold seas. In the Baltic Sea, the low salinity (from 0 to 2 up to 18) affects the behaviour of the spilled oil as well as the efficiency and ecological impacts of oil spill response methods such as mechanical collection and the use of dispersants. In the present study, mussels (Mytilus trossulus) were exposed under winter conditions (5 °C) to the water-accommodated fraction (WAF) of Naphthenic North Atlantic crude oil prepared by mechanical dispersion or to the chemically enhanced fraction (CEWAF) obtained using the dispersant Finasol OSR 51 at salinities of 5.6 and 15.0. Especially at the lower salinity, high bioaccumulation of polycyclic aromatic hydrocarbons was recorded in mussels in the CEWAF treatments, accompanied by increased biomarker responses. In the WAF treatments these impacts were less evident. Thus, the use of dispersants in the Baltic Sea still needs to be carefully considered.

Dietary crude oil exposure during sex differentiation skewed adult sex ratio towards males in the zebrafish

Dietary crude oil exposure has detrimental morpho-physiological effects in fishes, including endocrine disruption. However, little is known about how it influences sex differentiation and its potential for skewing sex ratios of populations. Appropriate sex ratio is important for maintaining effective population size and structure. Deviations of these ratios can compromise population growth and maintenance and may induce changes in a species' evolutionary trajectory. We assessed the potential of dietary exposure to crude oil (6.5, 11.4, and 17.5 mg/kg food) to alter sex differentiation in the zebrafish (Danio rerio) (20-35 days post fertilization (dpf)) and subsequently skew the adult (90 dpf) sex ratio. Multiple health- and fitness-related phenotypic traits (i.e., body mass and length, condition factor, heart rate, oxygen consumption, and their capacity to cope with hypoxia) were also assessed to better understand the effects of dietary crude oil exposure. We showed that dietary exposure to crude oil during the process of sex differentiation skewed sex ratio towards males (up to 0.34:1 female to male ratio in the highest oil concentration). Remarkably, this effect occurred independently of affecting physiological variables and female gonad characteristics, thus highlighting just how subtle the effects of dietary crude oil exposure can be. Our results suggest that, although fish were in an apparently healthy state during experimentation, sex ratio was still impacted, potentially compromising the resilience of the population. Therefore, considering how complex chemical mixtures affect organisms at several levels (molecular-individual) in experimental designs is warranted to better understand the implications of the exposures and the hazards that populations face in the wild.

Biodegradation of asphaltene by lipopeptide-biosurfactant producing hydrocarbonoclastic, crude oil degrading Bacillus spp

Asphaltene is the most recalcitrant compound in crude oil. Bacteria were isolated from crude oil contaminated soil and their efficiency for hydrocarbon degradation was determined using GC-MS and isolates were screened for biosurfactant production using FT-IR. Two Bacillus spp. having hydrocarbonoclastic and lipo-peptide biosurfactant-producing abilities were experimented for their asphaltene removal potential through oil removal efficiency (ORE%) and asphaltene degradation efficiency (ADE%). B. thuringeinsis SSL1 and B. cereus SSL3 could degrade 76.4% and 67.4% of asphaltene (20gL^-1), in vitro, respectively, which is much higher than previous reports. B. thuringiensis SSL1 is recommended for effective breakdown of asphaltene, total petroleum hydrocarbon, and polyaromatic hydrocarbon degradation, aided by its biosurfactants, which is useful for crude oil cleanup. Biosurfactants are important for enhancing the availability of hydrophobic hydrocarbons to bacteria, which is beneficial for efficient crude oil remediation. These findings could lead to more effective strategies for complete clean-up of crude oil pollution.