Concentrations Of Ethylbenzene Research Articles

Ethylbenzene and toluene interactions with biochar from municipal solid waste in single and dual systems

The present study investigated adsorptive removal of toluene and ethylbenzene from the aqueous media via using biochar derived from municipal solid waste (termed “MSW-BC”) in a single and binary contaminant system at 25–45 °C. The adsorption was evaluated at different pH (3–10), experimental time (up to 24 h), and initial adsorbate concentrations (10–600 μg/L) in single and binary contaminant system. A fixed-bed column experiment was also conducted using MSW-BC (0.25%) and influent concentration of toluene and ethylbenzene (4 mg/L) at 2 mL/min of flow rate. The adsorption of toluene and ethylbenzene on the MSW-BC was mildly dependent on the pH, and the peak adsorption ability (44–47 μg/g) was recorded at a baseline pH of ~8 in mono and dual contaminant system. Langmuir and Hill are the models that match the isotherm results in a single contaminant environment for both toluene (R2 of 0.97 and 0.99, respectively) and ethylbenzene (R2 of 0.99 and 0.99, respectively) adsorption. In the binary system, the isotherm models matched in the order of Langmuir > Hill > Freundlich for toluene, whereas Hill > Freundlich > Langmuir for ethylbenzene. The adsorption in the batch experiment was likely to take place via cooperative and multilayer adsorption onto MSW-BC involving hydrophobic, π- π and n- π attractions, specific interaction such as hydrogen–π and cation–π interactions, and van der Waals interactions. The thermodynamic results indicate exothermic adsorption occurred by physical attractions between toluene and ethylbenzene, and MSW-BC. The breakthrough behavior of toluene and ethylbenzene was successfully described with Yoon-Nelson and Thomas models. The data demonstrate that the low-cost adsorbent derived from the municipal solid waste can be utilized to remove toluene and ethylbenzene in landfill leachate.

Stable metal-organic frameworks based mixed matrix membranes for Ethylbenzene/N2 separation

To remove volatile organic compounds (VOCs) from air, N2 or other waste gas streams in industrial processes is significant to the environmental protection and human health, as well as gain the opportunity to reuse these valuable chemicals. Mixed matrix membranes (MMMs) based on metal-organic frameworks (MOFs) have been proved to have potential application in this field. In this work, MIL-101 and UiO-66 are selected to construct MMMs for efficient ethylbenzene separation because of following factors: (1) the high ethylbenzene adsorption capacities; (2) the three-dimensional channels with large pore size; and (3) the ideal hydrothermal stability of structures. [email protected] and [email protected] MMMs have been prepared in an environment-friendly way and evaluated for the ethylbenzene/N2 separation performance. SEM, TGA, FITR and XRD results indicate that continuous MMMs with different filler loading ratios have been fabricated successfully. The results show that [email protected] and [email protected] with the MOF loading radio of 20 wt% possess ethylbenzene/N2 permselectivity of 284 and 100 respectively at 25 °C, 0.05 MPa and moderate feed ethylbenzene concentration (1000 ppm), which increased by 10.5 and 3.0 times compared with the pristine Pebax membrane. Effects of upstream pressure, feed concentration, and operating temperature on separation performance have been investigated for ethylbenzene/N2 separation. Due to the selective adsorption capacity to ethylbenzene, as well as the large pore size of MIL-101(Cr), [email protected] can be applied as efficient membrane materials in ethylbenzene capture system for high concentration region at ambient temperature.

Exposure to BTEX concentration and the related health risk assessment in printing and copying centers.

This study was derived to investigation of BTEX (benzene, toluene, ethylbenzene, xylenes) concentrations in printing and copying centers (PCCs) in Ardabil city of Iran. Fifty-three PCCs were randomly selected from all the 136 number of PCCs and BTEX was sampled form their indoor air. The results showed that the concentration of BTEX in the indoor air PCCs is lower than the OELs (occupational exposure limit) in all cases. The obtained mean concentrations of benzene, toluene, ethylbenzene, and xylene were 93.6±63.2, 150.6±99.2, 34.3±16.8, and 29.5±15.2 μg/m3 respectively. Type of printer, number of printing and copying device, and type of ventilation system had significant influence on the BTEX concentration. The mean inhalation lifetime cancer risk (LTCR) value for benzene and ethylbenzene in the indoor air of the PCCs with LaserJet and inkjet printers was 44.4 × 10-6 and 153.3 × 10-6, and 23.4×10-6 and 54.2× 10-6, respectively, which were higher than EPA (Environmental Protection Agency) and World Health Organization (WHO) recommended limits. The hazard quotient (HQ) of benzene in the indoor air of the PCCs with inkjet printers was >1, which indicates that the non-carcinogenic risks associated with exposure to these compounds are considerable.

The concentration of benzene, toluene, ethylbenzene, and xylene in ambient air of the gas stations in Iran: A systematic review and probabilistic health risk assessment.

Exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) has been reported in gas stations. Exposure to BTEX can result in adverse health outcomes in workers such as cancer and neurological effects. The health risk assessments of exposure to BTEX could be useful in choosing suitable control measures. In this review, data from previous studies of gas station environments in Iran were collected from years 2000 to 2020. The health risk assessments were conducted through the estimation of cancer and noncancer risks using a Monte Carlo simulation based on the US Environmental Protection Agency method. The results showed that exposure to BTEX in some cities of Iran was greater than the occupational exposure limits. The results of cancer risk assessments demonstrated that cancer risk was not increased. However, results of noncancer risk assessments demonstrated that neurological toxicity from exposure to BTEX was significant in different cities of Iran. The health risk assessments indicated that workers at gas station are at health risk.

The effects of ethylbenzene on HEI-OC1 cells proliferation and oxidative stress level

Objective: To study the changes of proliferation and oxidation indexes of Cochlear hair cell line (HEI-OC1 cells) exposed to ethylbenzene. Methods: From July to December 2019, 11 groups with ethylbenzene concentrations of 0, 30, 60, 90, 300, 600, 900 μmol/L and 3, 6, 9, 10 mmol/L, were used to determine the proliferation activity of HEI-OC1 cells exposed to ethylbenzene for 24 hours, and the cells were treated with 0, 1, 2, 4, 8, 16, 32, 64 mmol/L ethylbenzene for 24 hours, then the 50% inhibitory concentration of ethylbenzene was calculated. After HEI-OC1 cells were exposed to 0, 6, 9 and 12 mmol/L ethylbenzene for 24 hours, the malondialdehyde (MDA) content, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured. Results: Compared with 0 mmol/L concentration group, the survival rate of HEI-OC1 cells at 6, 9, 12 mmol/L concentration was significantly decreased (P<0.01) . The 50% inhibitory concentration of ethylbenzene on HEI-OC1 cells was 12.86 mmol/L (R(2)=99.05) . There were significant differences in SOD and GSH-Px activity in HEI-OC1 cells treated with ethylbenzene at different concentrations (0, 6, 9, 12 mmol/L) for 24 hours (F=65.11, 6.48, 22.85, P<0.05) . Compared with 0 mmol/L concentration group, the MDA content of HEI-OC1 cells was significantly increased in 9 and 12 mmol/L concentration groups, the SOD activity was significantly decreased in 12 mmol/L concentration group, and the GSH-Px activity was significantly decreased in 6 and 12 mmol/L concentration groups. Conclusion: Ethylbenzene can inhibit the proliferation of HEI-OC1 cells and cause oxidative damage.

Exposure Assessment of Toxicologically Relevant Volatile Organic Compounds Emitted from Polymer-Based Costume Masks.

Plastic costume masks regularly exhibit unpleasant odors that may be associated with the emissions of volatile organic compounds (VOCs). Upon inhalation, VOCs might adversely affect the wearer's health if the exposure exceeds regulatory threshold values. The VOCs emitted from a selection of costume masks (n = 12) were characterized semiquantitatively with a screening method based on GC/MS measurements in dynamic headspace sampling mode. Furthermore, odors associated with the masks were evaluated by a sensory panel. Two masks emitted particularly high concentrations of ethylbenzene, xylenes, and cyclohexanone and exhibited the most intense and unpleasant odors, which were described as rubber-like, pungent, and leather-like. To simulate and assess the inhalation exposures for wearers of these masks, an innovative experimental setup based on a doll's head was developed, with sampling of emitted volatiles on adsorption material and subsequent analysis by thermal desorption-GC/MS. The measured inhalable concentrations of cyclohexanone exceeded the derived no-effect level (DNEL) for systemic effects on the general population over several hours of wearing, and also after repeated use. Importantly, the cyclohexanone DNEL was reevaluated in relation to a recent study on inhalation toxicity in rodents and was found to be significantly lower (1.4 mg·m-3) compared to the industry-derived values (10-20 mg·m-3), thus aggravating the health risks associated with inhalation exposure from some of the costume masks tested. Finally, a comparison of the inhalable concentrations derived from the simulated exposure assessments with those derived from measurements in miniaturized emission test chambers indicate that microchambers represent a useful tool for high-throughput analysis. The influences of temperature and inhalation/exhalation flow rates on VOC exposures were also studied.

Thermo-Chemical Treatment for Carcass Disposal and the Application of Treated Carcass as Compost

A mechanized thermo-chemical treatment system was developed to treat the undecomposed carcass and remediate livestock burial sites. Animal carcasses were thus processed via crushing, mixing, and treatment with quicklime treatment, heat treatment (200–500 °C), and mixing with sawdust. The machinery was applied to two sites where 16,000 chickens and 418 pigs had previously been buried in fiber-reinforced plastic storage bins. No dioxins were detected in the gas discharged during processing, and the concentration of total volatile organic compound, toluene, ethylbenzene, xylene, and styrene were 430.3, 139.0, 18.3, 21.4, and 10.4 μg/m3, respectively, which were below the air pollutant emission standards issued by the Korean Ministry of Environment. Korean standards stipulating the use of treated carcasses as compost (C, N, and P content, heavy metal concentration, Escherichia coli, and Salmonella) were met, but the germination index value was less than 70, not satisfying the criteria. Plant height, leaf length, leaf width, and dry weight of lettuce grown in soil amended with treated carcass product were significantly lower than those grown in low nutrient soil due to the poor germination index of the treated carcass. These results indicate that a composting process is required before the use of the treated carcass as a fertilizer. The addition of zeolite retarded the elution of ammonia from the carcasses and its efficiency was about 87.9%. It is expected that the mechanized thermo-chemical treatment process developed in this study could replace other technologies for the remediation of livestock burial sites.

BTEX compounds leachates from cigarette butts into water environment: A primary study.

Cigarette butts (CBs) are the most abundant types of litter in the environment and may contain toxic chemicals such as BTEX that pose serious risks to the water bodies and health of aquatic organisms. So far there is no systematic study on BTEX compounds (benzene, toluene, ethylbenzene, o-xylene, and p-xylene) leaching from CBs into water environments. In this work, the leaching concentrations of BTEX compounds in deionized water (DW) and river water (RW) samples were studied for the first time. The mean concentrations of benzene, toluene, ethylbenzene, p-xylene, and o-xylene at contact times of 15min to 1 day in water samples ranged from 0.13 to 0.18, 0.39-0.9, 0.11-0.25, 0.12-0.38, and 0.09-0.19μgL-1 respectively. Benzene, toluene, ethylbenzene, o-xylene and p-xylene were detected at all contact times in both DW and RW samples. There were no significant differences of the leachate levels of BTEX compounds between DW and RW samples. The highest and lowest mean concentration levels in both DW and RW samples were determined for toluene and o-xylene respectively. The time after smoking had a significant effect on BTEX levels in leachates. The concentration levels of benzene, toluene, ethylbenzene, o-xylene and p-xylene leachates in water samples, after only 15min, were reduced by 100, 93, 70, 68, and 59 percent respectively. Our data revealed that leached concentrations of benzene did not exceed the Water Framework Directive (WFD) guidelines, but with regard to the amount of CBs littered each year and other toxic chemicals contents of CBs this can still be a threat for aquatic creatures and possibly humans as well. Further studies are needed to cover the knowledge gap on the toxic leachates from CBs into water systems.

Area under the blood concentration-time curve (AUC) of ethylbenzene concentration in rats: relationship to inhalation and oral administration route-dose

For human risk assessment of toxic chemicals, especially volatile organic compounds (VOCs), the Ministry of the Environment, Government of Japan, has called for the interconversion of inhalation-dose and oral-dose data, two common exposure routes. To address this issue, the present study investigated the time-course changes of ethylbenzene (EB) concentrations in the blood of rats during and after 6-hr inhalation exposure to EB (25, 50, 100, and 200 ppm) and after oral administration of EB by a single oral gavage (25, 50, 100, and 200 mg/kg) of EB. The Area Under the blood concentration-time Curve (AUC) at each blood collection time point (0, 30, 60, 120, 180, 360, 420, 540, and 1440 min, after starting exposure) was determined. The inhalation dose of 25 ppm corresponded closely to the oral administration of 25 mg/kg・bw (r value of 0.859), and the inhalation dose of 200 ppm correlated with the oral administration of 100 mg/kg・bw (r value of 0.948). These results suggest that this comparison using the AUC data at each blood collection time point is valuable for understanding the route- and dose-effects of EB. This study will improve risk assessment of human exposure to EB and other VOCs.

Petroleum hydrocarbon pollution in the Niger Delta: human health risk assessment of BTEX in biota

Based on the context of extensive petroleum hydrocarbon pollution in southern Nigeria, the concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in seafood were determined, and the health risks of these compounds were evaluated. Biota samples (Crayfish, Goby fish, Moonfish, Mudskipper, Mullet, Sardine and Tilapia) were collected from the Bonny Estuary from 2016 to 2018 and analyzed according to US EPA method 5030/8260C to determine the concentrations of BTEX. Risk assessment of BTEX to humans through the dietary route was conducted based on the lifetime cancer risk (LTCR) for benzene and the hazard quotient (HQ) for BTEX. The following BTEX concentration ranges were observed: benzene: < 0.01–0.36 mg/kg; toluene: 0.22–19.85 mg/kg; ethylbenzene: < 0.00–1.54 mg/kg; xylene: < 0.00–7.28 mg/kg. The median LTCR for benzene in children and adults was 0.65 and 0.30, respectively, which are higher than the limit recommended by the World Health Organization. The model showed that the LTCR is reducible by 99.9% and 66.6% if the concentration of benzene is 0.00001 mg/kg, and fresh seafood consumption is reduced to 10.4 g/day. The HQ for all BTEX compounds was greater than 1 (benzene: 1.0 × 104 (child), 4.9 × 103 (adult); toluene: 1.9 × 105 (child), 9.0 × 104 (adult); ethylbenzene: 9.4 × 103 (child), 4.4 × 103 (adult); xylene: 2.5 × 104 (child), 1.2 × 104 (adult)), which signifies a high non-cancer health risk to humans. These results are a reflection of the high level of petroleum hydrocarbon pollution in southern Nigeria and the debilitating human health consequences that could accompany it.

Enhancement of ethylbenzene removal from contaminated gas and corresponding mechanisms in biotrickling filters by a biosurfactant from piggery wastewater

This study prepared a biosurfactant by using piggery wastewater to enhance ethylbenzene removal from contaminated gas in a biotrickling filter (BTF). Experiments were conducted to investigate the enhancement of ethylbenzene removal and the biofilm characteristics in present of the biosurfactant. Results demonstrated that the optimal biosurfactant concentration was 0.1 CMC and the corresponding ethylbenzene removal rate was 87.2%, much higher than that (68.9%) achieved in free of biosurfactant. The inlet ethylbenzene concentration and the empty bed residence time (EBRT) affected ethylbenzene removal as well. In present of 0.1 CMC of biosurfactant, ethylbenzene removal rate decreased from 87.2% to 72.2% with the increasing inlet ethylbenzene from 1000 to 2200 mg/m3, and decreased from 91.1% to 42.7% with the EBRT shorten from 30 to 7.5 s. For the enhancement mechanisms of ethylbenzene removal in BTF, the biosurfactant changed the contents of extracellular polymers (EPS) and decreased negative surface charge of the biofilm in the BTF, which improved the mass transfer of ethylbenzene to biofilm and facilitated the aggregation of microbes, and further improved the removal of ethylbenzene. All in all, the biosurfactant would be a feasible way to enhance the removal of ethylbenzene by the BTF.

Monitoring the BTEX Volatiles during 3D Printing with Acrylonitrile Butadiene Styrene (ABS) Using Electronic Nose and Proton Transfer Reaction Mass Spectrometry.

We describe a concept study in which the changes of concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and styrene within a 3D printer enclosure during printing with different acrylonitrile butadiene styrene (ABS) filaments were monitored in real-time using a proton transfer reaction mass spectrometer and an electronic nose. The quantitative data on the concentration of the BTEX compounds, in particular the concentration of carcinogenic benzene, were then used as reference values for assessing the applicability of an array of low-cost electrochemical sensors in monitoring the exposure of the users of consumer-grade fused deposition modelling 3D printers to potentially harmful volatiles. Using multivariate statistical analysis and machine learning, it was possible to determine whether a set threshold limit value for the concentration of BTEX was exceeded with a 0.96 classification accuracy and within a timeframe of 5 min based on the responses of the chemical sensors.

Research on emissions controlling of coal-made Fischer–Tropsch process diesel/methanol unconventional pollutants

ABSTRACT Thirty unconventional gaseous substances in Fischer–Tropsch process diesel/methanol-mixed fuel with different methanol blending ratios were measured and classified for diesel engine pollutant discharge. The measurement results showed high concentrations of several unconventional pollutants, including propylene, 1,3 butadiene, acrolein, benzene, toluene, ethylbenzene, and xylene, accounting for approximately 83% of the total concentration. The methanol blending ratio was increased from 0 to 15%, the amounts of unconventional pollutants such as olefins, alkanes, and aromatic hydrocarbons were decreased by 38.4%, 27.7%, and 23.7%, respectively, and the amounts of aldehydes and ketones were increased by 31.2%. The amounts of unconventional pollutants such as 1,3 butadiene, n-hexane, and benzene were decreased by 36.6%, 28.8%, and 29.2%, and the amount of acrolein was increased by 28.7%. At maximum torque, aromatic hydrocarbon emissions were reduced by 23.8%, aldehyde and ketone emissions were reduced by 44.8%, olefin emissions were increased by 142.8%, and alkane emissions were reduced by 14.5%; compared to maximum torque conditions, olefins under calibration category emissions were increased by 41.2%, alkane emissions were increased by 8.8%, aromatic hydrocarbon emissions were increased by 9.5%, and aldehyde and ketone emissions were increased by 25%.

Indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene in some Italian schools evaluation of areas with different air pollution

The air quality of indoor environments is an aspect of great importance and of growing interest, particularly considering the length of time that people stay in confined spaces. The objective of this study was to study the indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in 8 Italian schools, many of which are located in some of the most highly polluted areas in Italy. This wanted to provide useful information for understanding the status of air quality in sensitive indoor and outdoor areas (schools) and to support the development of recommendations and indications useful to territorial administrations in the improvement of environmental quality strategies. The sampling campaigns were performed with passive samplers from 2014 to 2015, studying both the hot and cold seasons. A common sampling and analytical protocol was applied in all the study areas. Passive sampler data were also compared with BTEX measurements from fixed-site monitoring stations selected as references for each school. Our findings showed the prevalence of low BTEX concentrations with relatively high values limited to toluene, ethylbenzene and xylene in a few monitoring sites and periods. The mean concentration values of benzene, toluene, ethylbenzene and xylene varied from 0.10 μg/m3 to 10.75 μg/m3, from 0.10 μg/m3 to 28.18 μg/m3, from 0.10 μg/m3 to 11.1 μg/m3 and from 0.10 μg/m3 to 14.45 μg/m3, respectively. In indoor environments, the concentrations were equal to or higher than the values measured outdoors in most cases, frequently reporting I/O ratios greater than 1.

Comparing BTEX concentration related to surgical smoke in different operating rooms

The available evidence on the indoor air quality of operating rooms (ORs) in the Low- and Middle-income Countries (LMICs) is very scarce. Moreover, there is no study on the comparing the concentration of indoor air pollutants in different ORs. Therefore, this study aimed to measure and compare the benzene, toluene, ethylbenzene and xylene (BTEX) concentrations in the air of different ORs in hospitals of Sabzevar, Iran. Moreover, carcinogenic and non-carcinogenic risk of exposure to these pollutants were assessed using Monte Carlo simulations technique. This cross-sectional study was based on volatile organic compounds (VOCs) passive sampling of eight ORs including General surgery, Curettage, Eye surgery, Neurosurgery, Orthopedic, Laparoscopic, Cesarean and Ear, nose, throat (ENT) in two monthly campaigns from November 2019 to February 2020. One-way ANOVA and Post-hoc analyses were used to compare the concentration of BTEX compounds in different ORs. The overall mean (standard deviation (SD)) of benzene, toluene, ethylbenzene, xylene and total BTEX concentrations were 10.0 (1.8), 7.2 (1.9), 1.8 (0.6), 0.4 (0.2) and 19.4 (4.1) μg/m3. The Curettage OR had the highest (12.93 μg/m3) and ENT OR had the lowest (7.42 μg/m3) benzene concentrations. The highest concentrations of toluene, ethylbenzene and total BTEX were observed in General surgery OR. The cancer risks of exposure to benzene in all ORs were higher than the acceptable range recommended by Unite State Environmental Protection Agency (USEPA, 1 × 106). However, the hazard quotient (HQ) values for all ORs were at safe level (HQ < 1). Overall, our study suggested that the concentrations of BTEX compounds were significantly difference in different ORs and benzene had a carcinogenic risk for personnel and surgical staff in different ORs.

Exposure levels of volatile organic compounds and potential health risks for passengers and workers at an intercity bus terminal

This work focuses on the concentration and health effects of volatile organic compounds (VOCs) at an intercity bus terminal in Taipei City, Taiwan. In this study, 36 VOCs were detected in the bus terminal, including 19 hazardous air pollutants. The measurement results indicate that ethanol, acetone, toluene, and methyl tert-butyl ether (MTBE) were the main VOCs dominating this bus terminal. Moreover, the average concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds was 106.0 μg/m3 inside the bus terminal, contributing to approximately 70% of the hazardous air pollutants. The measurement results suggest that traffic emissions, especially from diesel buses, were the major pollution sources in the bus terminal. The cancer risk for 1,3-butadiene, benzene, ethylbenzene, and naphthalene exceeded the suggested value by the U.S. EPA. In addition, the individual chronic hazard quotient of benzene was higher than the recommended level. The findings of this work imply that bus terminal workers face a potential health risk, which is a matter of concern.

Potential sources and measured concentrations of VOCs in Balikesir ambient atmosphere

The assessment of volatile organic compounds (VOCs) has become an important field of interest in atmospheric pollution. This study quantifies and characterizes the ambient levels and spatial distribution of VOCs in urban and rural areas of Balikesir city, Turkey. For these assessments, passive sampling of VOCs performed at approximately 50 locations in and around the city of Balikesir. Twenty-five VOCs were regularly monitored and analyzed with the GC-FID system. The sampling periods were carried out for seven-day periods during March and August 2010. In the study, mean ∑VOC concentrations were found to be as high 67 and 51 µg m–3 for the winter and summer seasons, respectively. Median concentrations of benzene, toluene, ethylbenzene, m,p-xylene and o-xylene were 2.6, 11, 1.30, 1.80 and 0.73 μg m-3, respectively. Although there were some changes between concentrations of VOC groups between the summer and winter campaigns, differences were not dramatic. Winter-to-summer ratios of the target compounds ranged from 0.2 (1,2,4-trimethylbenzene) to 9 (hexane). Most of the target compounds have higher concentrations in winter. Only few VOCs, including n-propylbenzene, 1,2,4- trimethylbenzene, 1-undecene and 1,2,4- trichlorobenzene have higher concentrations in summer. Spatial distribution of VOCs demonstrated that the roads are hot spots for measured VOC concentrations. The drinking water treatment plant, industrial solvent emissions from pesticide and insecticide applications in agriculture, and emissions from traffic were the sources that contribute to total VOC load in the Balikesir atmosphere.

Seasonal Variation, Sources, and Health Risk Assessment of Indoor/Outdoor BTEX at Nursery Schools in Hanoi, Vietnam

There is an increasing research interest in indoor air quality at schools as children who are among the most sensitive to air pollution spend a lot of time indoors. This study aims to estimate BTEX levels, sources, and assess their health risk at ten preschools in Hanoi, Vietnam. Two sampling campaigns were conducted in November and December, 2017, and May and June, 2018, with a total of 80 samples collected. BTEX were sampled by mini air samplers, and the analysis was performed by using GC/MS. During class, indoor concentrations of benzene, toluene, ethylbenzene, and xylene were within the range of 1.22–6.01, 1.6–63.4, 0.94–6.34, and 0.86–3.52 μg m−3, while corresponding values obtained in the absence of children were 1.62–6.90, 1.20–125.3, 0.58–25.1, and 0.60–6.65 μg m−3, respectively. Indoor/outdoor ratios of BTEX varied from school to school, and ranged from 0.4 to 14.2, implying the presence of indoor emission sources. Insignificant indoor sources of benzene were found in all examined schools, whereas there were sources of toluene, ethylbenzene, and xylenes, probably associated with paint’s solvents, glues, and cleaning agents. Outdoor BTEX originated from the common sources, being mainly composed of automobile traffic. There was insignificant cancer and non-carcinogenic risk to children at the monitored preschools, with LCR values within the range of 0.059–6.6 × 10−5, and HQ values below 0.31. Monte Carlo simulation revealed that indoor and outdoor concentrations of BTEX influenced the most the results on lifetime cancer risk for indoors and outdoors, with a typical contribution of more than 90% to LCR variance.

Removal of ethyl benzene vapor pollutant from the air using TiO2 nanoparticles immobilized on the ZSM-5 zeolite under UVradiation in lab scale.

Ethyl benzene is a volatile organic compound that is used in the many industries, including Oil and Gas, Oil colored and Insecticides. Due to the toxic effects of this chemical substance control and elimination of this vapor is necessary. Photo catalytic degradation is a possible method to remove organic compounds from air. This study was performed to determine the efficiency of photo catalytic removal of ethyl benzene vapor using TiO2 nanoparticles immobilized on the ZSM-5 zeolite under UV radiation. This was an experimental study. The surface and volume of the pores of the bed were determined by the Bruner-Emmett-Teller (BET) method and Surface structure was determined by Scanning Electron Microscope (SEM), EDAX and X-Ray Diffraction (XRD). Dynamic air flow and different concentrations of ethyl benzene (25, 75 and 125ppm) and flow rates (0.5, 0.7, and 1.0L/min) were produced and the removal efficiency of ethyl benzene vapor were investigated using ZSM-5 and TiO2/ZSM-5/UV processes. The temperature and relative humidity were set at 25 ± 2°c and 35%. Evaluations for BET showed the specific surface areas decreased after loading TiO2 on ZSM-5. XRD and EDAX analysis and SEM images showed that zeolite structure was stabled and nanoparticles were successfully stabilized on Ze. The results showed that the highest removal efficiency (52%) by the process of TiO2/ZSM-5/UV (5wt%) at concentration 25ppm and flow rate 0.5L/min respectively. The result of this study showed that the TiO2/ZSM-5catalyst may be a applicable and hopeful method to removal of ethyl benzene from air flow under UV irradiation.

Simulating the spatiotemporal distribution of BTEX with an hourly grid-scale model.

Modeling approaches have been utilized to simulate ambient pollutant concentrations, but very limited efforts have been made to estimate volatile organic compounds in the atmosphere. For this reason, an hourly grid-scale simulation model was developed to determine ambient air concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX data were collected over a one-year time frame from the database of the Taiwan Environmental Protection Administration's photochemical assessment monitoring stations. Multivariate linear regression models were used along with correlation analysis to simulate hourly grid-scale BTEX concentrations, using criteria pollutants and selected meteorological variables as predictors. The simulation model was validated in the southern Taiwan area via a portable micro gas chromatography system (n=121) with significant correlation (r=0.566**, ** indicated p<0.01). Moreover, the grid-scale model was applied to areas covering about 72% of the population in Taiwan. A geographic information system (GIS) was used to visualize the spatial distribution of BTEX concentrations from the modeling results. This new grid-scale modeling strategy, which incorporated the GIS output of the simulated data, provides a useful alternative tool for personal exposure analysis and health risk assessment of ambient air BTEX.