Benzene, Toluene, Ethylbenzene And Xylene Research Articles

Enhancing high selectivity production of light aromatics from in-situ catalytic upgrading of cellulose pyrolysis vapors by regulating hierarchical core-shell ZSM-5@MCM-41

The catalytic upgrading of cellulose pyrolysis vapors is one of the effective methods to realize its high value utilization. Tuning the pore structure and acid sites of ZSM-5 (Z5) is a necessary strategy to develop effective catalysts for the production of light aromatics and the inhibition of carbon formation. In this study, a core-shell structure ZSM-5 @MCM-41 was developed and used for the first time in catalytic fast pyrolysis (CFP) of cellulose to prepare light aromatic hydrocarbons. The successful synthesis of the hierarchical core-shell ZSM-5 @MCM-41 was confirmed by nitrogen physisorption, X-ray diffraction (XRD), and transmission electron microscope (TEM) analysis. In aromatic hydrocarbon production, 1.0SH-Z5 @ M41 (1.0 mol/L, ZSM-5 @MCM-41) has the highest relative content of 98.76%. The relative content of BTEX (benzene, toluene, ethylbenzene, and xylene) is up to 89.83%, which is 2.39 times that of traditional microporous Z5. The quadratic polynomials were developed to correlate the Brønsted-to-Lewis acid site strength ratio (BLR) and mesopore-to-micropore volume ratio (MMR) with the relative content of BTEX. The mechanism of in-situ catalytic upgrading of cellulose pyrolysis vapor over ZSM-5 @MCM-41 was revealed. Due to high selectivities and low coke formation, ZSM-5 @MCM-41 offers an improved option for making monocyclic aromatics from cellulosic biomass.

Fabrication and performance evaluation of tannin iron complex (TA-FeIII/PES) UF membrane in treatment of BTEX wastewater

Oil exploration generates produced water that is characterized as hazardous and toxic waste. Produced water contains a mixture of various pollutants, including monoaromatic hydrocarbons BTEX (benzene, toluene, ethylbenzene, and xylene), compounds that are carcinogenic even in small concentrations. In this study, tannin iron complex (TA-FeIII), blended into polyethersulfone (PES) membrane was evaluated for the treatment of BTEX-containing wastewater. The membranes were fabricated using the non-solvent induced phase separation (NIPS) method and loading of the TA-FeIII complex on the membranes varied from 0–0.9 wt%. The fabricated membranes were characterized using various techniques such as scanning electron microscopy (SEM), water contact angle (WCA), Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM) to check the surface morphology, hydrophilicity, surface functionality and surface roughness of the fabricated membranes, respectively. The TA-FeIII modified membranes showed increased pure water flux from 100 (PES 0) to ∼150 (PES 0.9) L/(m2‧h) at 100 kPa. The performance of the fabricated membranes was tested using 70 mg/L synthetic BTEX solution. Overall BTEX rejection > 70% was achieved at increasing TA-FeIII loadings compared to BTEX rejection < 65% for the pure PES membrane. Rejection of the BTEX compounds was mainly through the size exclusion mechanism. These modified TA-FeIII/PES UF membranes proved to be effective in the treatment of BTEX-containing water, and also have the potential to be applied in oily wastewater treatment.

Microfluidic-assisted toxicity studies of jet fuels on environmental microorganisms – Towards new lab-on-a-chip sensing applications

In this paper, a lab-on-a-chip (LOC) for cellular studies with software-enhanced metrological parametrisation of toxin-to-cell effects on-chip is shown. A special design of LOC is proposed herein whose performance prior to use was confirmed utilising numerical simulations based on a laminar exhaust microflow module. Model microorganisms – Euglena gracilis – were used as a bioindicator to evaluate the toxicity of jet fuels, i.e. Jet A-1 and Jet A-1 + HEFA (Hydroprocessed Esters and Fatty Acids). Apart from the biological results that show notable cell degradation for both of the fuels after 20 min of exhaust exposure (e.g. mobility decrease by 80 % and 100 % for Jet A-1 and Jet A-1 + HEFA), interesting outcomes were also obtained in an exhaust gas chromatography analysis, being in strong correlation with the observed euglena colony behaviour. The major focus was put herein on the concentration of VOCs (Volatile Organic Compounds) and BTEX (Benzene, Toluene, Ethylbenzene and Xylene isomers). Although the sum of volatile hydrocarbon compounds in the exhaust gas decreased due to the addition of HEFA-type hydrocarbons to the fuel, the concentration of the most toxic, BTEX group, was increased about two times compared to the standard Jet A-1. On that basis, our preliminary tests show that further research in this regard is required, in the context of both the toxin-to-cell impact and its direct correlation with the fuel composition.

Air pollution characteristics and human health risk assessment of underground parking garages in Xi’an, China

Due to the rapid increase of population density and automobile vehicle numbers in mega-cities, large underground garages have become universal supporting facilities to meet the demand for parking spaces in the recently-built commercial complexes and high-rise residential communities. Natural ventilation was insufficient to discharge vehicle-induced pollutants out of the enclosed underground spaces, which could pose a potential threat to people’s health. This study aims to determine the spatial and temporal distribution characteristics of pollutants concentration and the health risk of underground parking garages (UPGs)’ staff and users. Field measurements were conducted on the air pollutants concentrations and the users’ exposure characteristics in 11 commercial UPGs and three high-rise residential UPGs with natural ventilation in Xi’an. The pollutants concentrations were higher in the afternoon and morning of commercial and high-rise residential UPGs. In general, the particulate matters (PM2.5 and PM10), HCHO, TVOC and BTEX (benzene, toluene, ethylbenzene and xylenes) concentrations in commercial and residential UPGs were 0.069/0.067 mg/m³, 0.12/0.097 mg/m³, 0.014/0.017 mg/m³, 1.8/1.8 mg/m³, 0.056/0.10 mg/m³, 0.19/0.29 mg/m³ and 0.41/0.49 mg/m³, respectively. TVOC and BTEX concentrations in UPGs significantly correlated with traffic volume ( p < 0.01). In different groups, the entropy values of carcinogenic and non-carcinogenic risks were: staffs > children travelling with adults > adults. In particular, occupational long-term (employee) exposure could lead to both carcinogenic and non-carcinogenic risks.

BTEX exposure in indoor air in schools in Bulgaria

Exposure to indoor air pollutants is one of the primary environmental health stressors, the most important categories of chemicals that occur in the indoor air are BTEX (benzene, toluene, ethylbenzene and xylenes). All of them are used in many commercial building products and materials use indoor. Each of the chemicals in the mixture of concern is volatile, well absorbed, extensively metabolized, and does not persist in the body for long periods of time. All of the BTEX chemicals can produce neurological impairment. The aim of this work is on research and analysis of indoor air quality. seasonal fluctuations and to assess the impact of chemical pollutants in a closed environment in southwest Bulgaria.

Catalytic co-cracking of biomass and waste plastics with sawdust mediated ZSM-5 synthesized via activating gel process

Minimizing the catalyst cost is critical to achieving long-term economic feasibility for obtaining bio-chemicals directly from biomass. In the present study, low cost ZSM-5 was synthesized via hydrothermal crystallization of the activated aluminosilicate gel without adding any organic ammonium templates and additional seed crystals. The activation process promoted the depolymerization of the silica-alumina species and the formation of active pasty gel containing nucleation precursors, consequently accelerating the subsequent crystallization reaction. The addition of eucalyptus sawdust (ES) in the synthesis process increased the BET (Brunauer-Emmett-Teller) surface area and acidity of the resultant zeolites. The ES-mediated ZSM-5 (AGZ-10) achieved a higher benzene, toluene, ethylbenzene and xylene (BTEX) carbon yield (18.9 %) from co-cracking of ES and waste plastics (WP) (ES/WP mass ratio at 1:1) at 500 °C and exhibited better synergistic effect and anti-coking ability compared to the commercial ZSM-5. The results provide an efficient synthetic strategy to produce low-cost zeolites, and a promising technique to effectively utilize biomass and plastic wastes.

Application of Headspace-SIFT-MS to Direct Analysis of Hazardous Volatiles in Drinking Water

Harmful volatile organic compounds (VOCs) are present in drinking water due to anthropogenic activities, such as oil refining (e.g., benzene) and disinfection (e.g., the so-called trihalomethanes, THMs). Gas chromatography (GC)-based techniques are widely applied for analysis of these compounds in the laboratory but have some throughput drawbacks due to sample preparation and the extended analysis time (due to chromatographic separation). Selected ion flow tube mass spectrometry (SIFT-MS) is a direct-injection mass spectrometry (DIMS) technique that has potential to reduce sample preparation and analysis times through direct analysis of aqueous headspace with no preconcentration, drying, or other water management. This study applies headspace-SIFT-MS to the analysis of benzene, related petroleum aromatics, and THMs to evaluate the potential for enhanced sample throughput for drinking water analysis (10 samples per hour). Headspace-SIFT-MS achieved a limit of quantitation (LOQ) of 0.1 to 0.2 μg L−1 for benzene, toluene, ethylbenzene and xylenes (BTEX), and 1 to 2 μg L−1 for the THMs. These LOQs achieve the current European Union and United States regulatory limits but are higher than modern GC methods. Therefore, the potential application of SIFT-MS is envisaged to lie in rapid screening in the laboratory, or field-based real-time monitoring.

Isolation of Pseudomonas aromaticivorans sp. nov from a hydrocarbon-contaminated groundwater capable of degrading benzene-, toluene-, m- and p-xylene under microaerobic conditions.

Members of the genus Pseudomonas are known to be widespread in hydrocarbon contaminated environments because of their remarkable ability to degrade a variety of petroleum hydrocarbons, including BTEX (benzene, toluene, ethylbenzene and xylene) compounds. During an enrichment investigation which aimed to study microaerobic xylene degradation in a legacy petroleum hydrocarbon-contaminated groundwater, a novel Gram-stain-negative, aerobic, motile and rod-shaped bacterial strain, designated as MAP12T was isolated. It was capable of degrading benzene, toluene, meta- and para- xylene effectively under both aerobic and microaerobic conditions. The 16S rRNA gene sequence analysis revealed that strain MAP12T belongs to the genus Pseudomonas, with the highest 16S rRNA gene similarity to Pseudomonas linyingensis LYBRD3-7T (98.42%), followed by Pseudomonas sagittaria JCM 18195T (98.29%) and Pseudomonas alcaliphila JCM 10630T (98.08%). Phylogenomic tree constructed using a concatenated alignment of 92 core genes indicated that strain MAP12T is distinct from any known Pseudomonas species. The draft genome sequence of strain MAP12T is 4.36 Mb long, and the G+C content of MAP12T genome is 65.8%. Orthologous average nucleotide identity (OrthoANI) and digital DNA–DNA hybridization (dDDH) analyses confirmed that strain MAP12T is distinctly separated from its closest neighbors (OrthoANI < 89 %; dDDH < 36%). Though several members of the genus Pseudomonas are well known for their aerobic BTEX degradation capability, this is the first report of a novel Pseudomonas species capable of degrading xylene under microaerobic conditions. By applying genome-resolved metagenomics, we were able to partially reconstruct the genome of strain MAP12T from metagenomics sequence data and showed that strain MAP12T was an abundant member of the xylene-degrading bacterial community under microaerobic conditions. Strain MAP12T contains ubiquinone 9 (Q9) as the major respiratory quinone and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine as major polar lipids. The major cellular fatty acids of strain MAP12T are summed feature 3 (C16:1ω6c and/or C16:1ω7c), C16:0 and summed feature 8 (C18:1ω6c and/or C18:1ω7c). The results of this polyphasic study support that strain MAP12T represents a novel species of the genus Pseudomonas, hence the name of Pseudomonas aromaticivorans sp. nov. is proposed for this strain considering its aromatic hydrocarbon degradation capability. The type strain is MAP12T (=LMG 32466, =NCAIM B.02668).

Catalytic pyrolysis of waste polyethylene into benzene, toluene, ethylbenzene and xylene (BTEX)-enriched oil with dielectric barrier discharge reactor

The increasing demand for plastics has resulted in significant plastic waste accumulation and environmental pollution. Catalytic pyrolysis is an attractive treatment method to mitigate the plastic waste management problems and recover high-value oil products. In our study, waste polyethylene (PE) was pyrolyzed to produce benzene, toluene, ethylbenzene and xylene (BTEX)-enriched oil a using dielectric barrier discharge plasma catalytic pyrolysis reactor. Ga-modified Hydro-Zeolite Socony Mobile-Five (HZSM-5) was used as a pyrolysis catalyst. The effects of the PE to Ga/HZSM-5 ratio and discharge power on BTEX enhancement and carbon deposition are discussed. The greatest BTEX selectivity (77.04%) and relatively low coke yield (1.37%) were achieved when the PE/(Ga/HZSM-5) ratio was 2:1 with a non-thermal plasma (NTP) discharge power of 20 W. The regeneration effects of conventional thermal oxidation and NTP on the zeolite catalyst were compared. NTP regeneration at a low temperature (150 °C) achieved the same coke removal rate as that of thermal regeneration at high temperatures (500 °C). Ga/HZSM-5 subjected to NTP regeneration showed higher activity for BTEX formation (BTEX selectivity was 42.10%) as compared to that shown by Ga/HZSM-5 subjected to thermal regeneration (BTEX selectivity was 40.59%). The NTP synergistic catalytic pyrolysis of plastics over Ga/HZSM-5 was found to be a promising strategy for mitigating the plastic waste management problems and upgrading the quality of oil products.

Big-Data Analysis and Machine Learning Based on Oil Pollution Remediation Cases from CERCLA Database

The U.S. Environmental Protection Agency’s (EPA) Superfund—the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) database—has collected and built an open-source database based on nearly 2000 US soil remediation cases since 1980, providing detailed information and references for researchers worldwide to carry out remediation work. However, the cases were relatively independent to each other, so the whole database lacks systematicness and instructiveness to some extent. In this study, the basic features of all 144 soil remediation projects in four major oil-producing states (California, Texas, Oklahoma and Alaska) were extracted from the CERCLA database and the correlations among the pollutant species, pollutant site characteristics and selection of remediation methods were analyzed using traditional and machine learning techniques. The Decision Tree Classifier was selected as the machine learning model. The results showed that the growth of new contaminated sites has slowed down in recent years; physical remediation was the most commonly used method, and the probability of its application is more than 80%. The presence of benzene, toluene, ethylbenzene and xylene (BTEX) substances and the geographical location of the site were the two most influential factors in the choice of remediation method for a specific site; the maximum weights of these two features reaches 0.304 and 0.288.

The Effect of Y Zeolites with Different Pores on Tetralin Hydrocracking for the Production of High-Value Benzene, Toluene, Ethylbenzene and Xylene Products

A series of Y zeolites with different pore properties was prepared as a support for hydrocracking catalysts for the production of BTEX (benzene, toluene, ethyl-benzene, and xylene) from tetralin. Some important characterizations, including N2 adsorption–desorption, NH3-TPD, Py-IR, and HRTEM, were applied to obtain the properties of different catalysts. Meanwhile, the tetralin hydrocracking performances of those catalysts were investigated on a high-pressure fixed-bed microreactor. The results showed that Si/Al ratio is the core property of zeolites and that the increase in the Vmicro/Vmeso of zeolites could facilitate the formation of BTEX products by hydrocracking tetralin. The method of hydrocracking tetralin was proposed. It was also found that the hydrogenation–cracking path was controlled by aromatic saturation thermodynamics, and strong acidity aided the backward shift of equilibrium temperature.

The concentration of BTEX in selected urban areas of Malaysia during the COVID-19 pandemic lockdown

Volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene (BTEX) are air pollutants that harm human health. This study aims to identify BTEX concentrations before the lockdown known as the Movement Control Order was imposed (BMCO), during the implementation of the Movement Control Order (MCO), and then during the Conditional Movement Control Order (CMCO). These orders were introduced during the COVID-19 pandemic in Malaysia. The study utilised data measured by the continuous monitoring of BTEX using online gas chromatography instruments located at three urban area stations. The results showed that the BTEX concentrations reduced by between −38% and −46% during the MCO compared to the BMCO period. The reduction of human mobility during the MCO and CMCO influenced the lower BTEX concentrations recorded at a station within the Kuala Lumpur area. The results of the BTEX diagnostic ratios and principal component analysis showed that the major source of BTEX, especially during the BMCO and CMCO periods, was motor vehicle emissions. Further investigation, using correlation analysis and polar plots, showed that the BTEX concentrations were also influenced by meteorological variables such as wind speed, air temperature and relative humidity.

BTEX induces histopathological alterations, oxidative stress response and DNA damage in the testis of the freshwater leech Erpobdella johanssoni (Johansson, 1927)

The widespread application of the hydrocarbons benzene, toluene, ethylbenzene and xylene (BTEX) has led to their consideration as major aquatic environmental pollutants, and exposure to these hydrocarbons has become a serious concern given their detrimental health effects on aquatic species. We investigated in the present study the impact of chronic exposure to BTEX on the testis of the freshwater leech Erpobdella johanssoni. The results revealed that BTEX induced severe histological alterations revealed by vacuolar degeneration in the spermatogenic cysts, and a complete loss of normal cysts was observed. The cytophore was grossly destroyed, and extensive necrosis and detached germ cells from cytophore were observed. Interestingly, BTEX exposure induced a significant increase in malondialdehyde (MDA) levels by 85.71% in the testicular tissue of treated leeches compared to the control (P < 0.00005), whereas the activity levels of SOD, GPx and CAT antioxidant biomarkers were significantly decreased by 60%, 81.81% and 47.5%, respectively. Additionally, using the alkaline comet assay, we observed that BTEX exposure induced significant DNA fragmentation in the testis cells of treated leeches compared to controls (P < 0.00005). Overall, this study unravels the histopathologic, oxidative stress and DNA damage induced by BTEX on the testis of the freshwater leech E. johanssoni.

Synthetic Saccharomyces cerevisiae tolerate and degrade highly pollutant complex hydrocarbon mixture

Fungal laccase (Lac) has become a very useful biocatalyst in different industries, bio-refineries and, most importantly, bioremediation. Many reports have also linked hydrocarbon tolerance and degradation by various microorganisms with Lac secretion. In this study, Trametes trogii Lac (Ttlcc1) was engineered into Saccharomyces cerevisiae strain CEN.PK2–1 C under the constitutive GPD promoter (pGPD) for multi-fold synthesis with efficient hydrocarbon tolerance and degradation. Protein expression in heterologous hosts is strictly strain-specific, it can also be influenced by the synthetic design and culture conditions. We compared synthetic designs with different shuttle vectors for the yeast strains and investigated the best culture conditions by varying the pH, temperature, carbon, nitrogen sources, and CuSO4 amount. Two S. cerevisiae strains were built in this study: byMM935 and byMM938. They carry the transcription unit pGPD-Ttlcc1-CYC1t either inside the pRSII406 integrative plasmid (byMM935) or the pRSII426 multicopy plasmid (byMM938). The performance of these two synthetic strains were studied by comparing them to the wild-type strain (byMM584). Both byMM935 and byMM938 showed significant response to different carbon sources (glucose, galactose, lactose, maltose, and sucrose), nitrogen sources (NH4Cl, NH4NO3, KNO3, malt extract, peptone, and yeast extract), and solid state fermentation of different plant biomasses (bagasse, banana peels, corn cob, mandarin peels, and peanut shells). They performed best in optimized growth conditions with specific carbon and nitrogen sources, and a preferred pH in the range 3.5–4.5, temperature between 30 and 40 0C, and 1 mM CuSO4. In optimized yeast-growth medium, strain byMM935 showed the highest laccase activities of 1.621 ± 0.063 U/mL at 64 h, whereas byMM938 gave its highest activity (1.417 ± 0.055 U/mL) at 48 h. In this work, we established, by using Bushnell Hass synthetic medium, that the new Ttlcc1-yeast strains tolerated extreme pH and complex hydrocarbon mixture (CHM) toxicity. They degraded 60–90% of the key components in CHM within 48 h, including poly-cyclic aromatic hydrocarbons, alkyl indenes, alkyl tetralines, alkyl benzenes, alkyl biphenyls, and BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes). This is the first report on the hydrocarbon degradation potential of a Ttlcc1-yeast. Compared to the native organism, such synthetic strains are better suited for meeting growing demands and have potentials for application in large-scale in situ bioremediation of hydrocarbon-polluted sites.

Global preterm births attributable to BTEX (benzene, toluene, ethylbenzene, and xylene) exposure

Epidemiological studies have shown that long-term exposure to toxic volatile organic compounds, such as benzene, toluene, ethylbenzene, and xylene (BTEX), is associated with preterm births (PTB). However, global PTB attributable to long-term BTEX exposure has not been reported in the literature yet. In this study, we employed a global chemical transport model, GEOS-Chem (Goddard Earth Observing System coupled with chemistry), in conjunction with an epidemiological model, to quantify the global country-specific PTB associated with long-term BTEX exposure at the horizontal resolution of 1 km × 1 km for the year 2015. Model simulated surface annual mean BTEX concentrations in GEOS-Chem have been thoroughly evaluated against global in-situ observations, which demonstrated that model simulated BTEX concentrations fairly agreed with observations but tended to be underestimated in India. Our study found that the global annual total PTB attributable to BTEX was 2.01 million [95% confidence interval (95CI): 1.16–2.70 million] in 2015, with largest contributions from India (28.3%), followed by China (27.5%), Pakistan (6.2%), Indonesia (4.2%), Bangladesh (3.7%) and United States (2.3%). The global annual total PTB due to BTEX exposure accounted for 19.6% (95CI: 11.3–26.4%) relative to the global annual total all-cause PTB (10.24 million) in 2015. Our study has significant implications on air pollution mitigation policy associated with country-specific anthropogenic BTEX emission reductions to achieve the benefit of human health.

The role of temperature profile during the pyrolysis of end-of-life-tyres in an industrially relevant conditions auger plant

Pyrolysis is a chemical recycling process of interest as a means to achieve a sustainable circular economy for end-of-life tyres (ELTs). In the pyrolysis process, ELTs are converted into tyre pyrolysis gas (TPG), tyre pyrolysis oil (TPO) and raw recovered carbon black (RRCB). This work investigates for the first time the effect of different temperature profiles by using a single-auger pyrolysis reactor in an industrially relevant scale (TRL-5). Since the development of this process at this representative scale is quite limited and the temperature profile has not been previously studied, the results achieved in this work can provide a useful database for the development of this process at industrial scale. For this purpose, two different sources of ELTs, commercial truck tyres (CTTs) and passenger car tyres (PCTs), were used. Accordingly, the experimental campaign was conducted using two different incremental temperature profiles (425-550-775 °C and 600-700-800 °C) based on those that can be replicated in an industrial-scale auger pyrolysis plant. For the sake of comparison, two isothermal heating conditions (500-500-500 °C and 600-600-600 °C) were also tested. The results confirmed the remarkable influence of temperature profile on both the distribution and properties of products. The 425-550-775 °C temperature profile was found to enhance limonene production, which is associated with the minimisation of secondary reactions in the first heating zone of the reactor. Additionally, there were very low carbonaceous deposits found in the RRCB because of the high severity of devolatilisation conditions in the third heating zone of the reactor. On the other hand, when the temperature profile was raised, the production of single-ring aromatics, particularly benzene, toluene, ethylbenzene and xylenes (BTEX) significantly increased in the TPO at the expense of limonene. Thus, from this strategy, it is possible to tune the properties of the products depending on the requirements of the application in a single step, getting closer for circular economy in the ELT recycling domain.

Association between BTEX (benzene, toluene, ethylbenzene and xylene) concentration in ambient air with hematological and spirometric indices: a population-based study

The study aimed to evaluated the relationship between BTEX (benzene, toluene, ethyl benzene and xylene) concentrations in the ambient air with human biomarkers in Assaluyeh city, Iran. According to the results, the average benzene concentration in the high pollution city was measured at 30.05 µg/m3, which is higher than the value recommended (0.03 mg/m3) by the U.S. Environmental Protection Agency (U.S. EPA). The mean spirometric parameters of the resident population in two high and low pollution areas were forced vital capacity (FVC) (high = 4.52; low = 4.78 L), forced expiratory volume in 1 second (FEV1) (high = 3.52; low = 3.88 L), FEV1/FVC (high = 77.9; low = 82.08%), peak expiratory flow (PEF) (high = 9.76; low = 27.85 L/min), and forced inspiratory flow 25–75% (FEF25-75) (high = 3.17; low = 3.95 L/s). Besides, no statistically significant difference was observed between the two groups by comparison of blood tests and the mean concentration of BTEX. BTEX concentration was measured at zero in low pollution areas due to lack of traffic and industries, but it was higher than the respiratory air standard and in the high-pollution area due to the being close to gas and petrochemical stations and industries in the surrounding. As a result, prolonged exposure to higher concentrations of BTEX increases the risks of respiratory dysfunction.

Microbial bioremediation of produced water under different redox conditions in marine sediments

The discharge of produced water from offshore oil platforms is an emerging concern due to its potential adverse effects on marine ecosystems. In this study, we investigated the feasibility and capability of using marine sediments for the bioremediation of produced water. We utilized a combination of porewater and solid phase analysis in a series of sediment batch incubations amended with produced water and synthetic produced water to determine the biodegradation of hydrocarbons under different redox conditions. Significant removal of benzene, toluene, ethylbenzene and xylene (BTEX) compounds was observed under different redox conditions, with biodegradation efficiencies of 93−97% in oxic incubations and 45−93% in anoxic incubations with nitrate, iron oxide or sulfate as the electron acceptor. Higher biodegradation rates of BTEX were obtained by incubations dominated by nitrate reduction (104−149 nmolC/cm3/d) and oxygen respiration (52−57 nmolC/cm3/d), followed by sulfate reduction (14−76 nmolC/cm3/d) and iron reduction (29−39 nmolC/cm3/d). Chemical fingerprint analysis showed that hydrocarbons were biodegraded to smaller alcohols/acids under oxic conditions compared to anoxic conditions with nitrate, indicating that the presence of oxygen facilitated a more complete biodegradation process. Toxicity of treated produced water to the marine copepod Acartia tonsa was reduced by half after sediment incubations with oxygen and nitrate. Our study emphasizes the possibility to use marine sediment as a biofilter for treating produced water at sea without extending the oil and gas platform or implementing a large-scale construction.

The Porcine Odorant-Binding Protein as a Probe for an Impedenziometric-Based Detection of Benzene in the Environment.

Odorant-binding proteins (OBPs) are a group of small and soluble proteins present in both vertebrates and insects. They have a high level of structural stability and bind to a large spectrum of odorant molecules. In the environmental field, benzene is the most dangerous compound among the class of pollutants named BTEX (benzene, toluene, ethylbenzene, and xylene). It has several effects on human health and, consequently, it appears to be important to monitor its presence in the environment. Commonly, its detection requires the use of very sophisticated and time-consuming analytical techniques (GC-MS, etc.) as well as the presence of specialized personnel. Here, we present the application of an odorant-binding protein (pOBP) isolated from pigs as a molecular recognition element (MRE) for a low-energy impedenziometric biosensor for outdoor and real-time benzene detection. The obtained results show that the biosensor can detect the presence of 64 pM (5 µg/m3) benzene, the limit value of exposure for human health set by the European Directive 2008/50/EC.

An assessment of spatial distribution and atmospheric concentrations of ozone, nitrogen dioxide, sulfur dioxide, benzene, toluene, ethylbenzene, and xylenes: ozone formation potential and health risk estimation in Bolu city of Turkey.

Atmospheric pollutants including ozone, nitrogen dioxide, sulfur dioxide, and BTEX (benzene, toluene, ethylbenzene, and xylenes) compounds were evaluated concerning their spatial distribution, temporal variation, and health risk factor. Bolu plateau where sampling was performed has a densely populated city center, semi-rural areas, and forested areas. Additionally, the ozone formation potentials of BTEXs were calculated, and toluene was found to be the most important compound in ground level ozone formation. The spatial distribution of BTEXs and nitrogen dioxide pollution maps showed that their concentrations were higher around the major roads and city center, while rural-forested areas were found to be rich in ozone. BTEXs and nitrogen dioxide were found to have higher atmospheric concentrations in winter. That was mostly related to the source strength and low mixing height during that season. The average toluene to benzene ratios demonstrated that there was a significant influence of traffic emissions in the region. Although there was no significant change in sulfur dioxide concentrations in the summer and winter seasons of 2017, the differences in the spatial distribution showed that seasonal sources such as domestic heating and intensive outdoor barbecue cooking were effective in the atmospheric presence of this pollutant. The lifetime cancer risk through inhalation of benzene was found to be comparable with the limit value (1 × 10-6) recommended by USEPA. On the other hand, hazard ratios for BTEXs were found at an acceptable level for different outdoor environments (villages, roadside, and city center) for both seasons.