Determination of biodegradation process of benzene, toluene, ethylbenzene and xylenes in seabed sediment by purge and trap gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Han, Dongqiang [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics; China Pharmaceutical Univ., Nanjing (China). Physics Teaching and Research Section, Dept. of Basic Sciences; Ma, Wanyun; Chen, Dieyan [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics

2007-12-15

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are commonly found in crude oil and are used in geochemical investigations as direct indicators of the presence of oil and gas. BTEX are easily volatile and can be degraded by microorganisms, which affect their precise measurement seriously. A method for determining the biodegradation process of BTEX in seabed sediment using dynamic headspace (purge and trap) gas chromatography with a photoionization detector (PID) was developed, which had a detection limit of 7.3-13.2 ng L{sup -1} and a recovery rate of 91.6-95.0%. The decrease in the concentration of BTEX components was monitored in seabed sediment samples, which was caused by microorganism biodegradation. The results of BTEX biodegradation process were of great significance in the collection, transportation, preservation, and measurement of seabed sediment samples in the geochemical investigations of oil and gas. (orig.)

Uptake of toluene and ethylbenzene by plants: removal of volatile indoor air contaminants.

Science.gov (United States)

Sriprapat, Wararat; Suksabye, Parinda; Areephak, Sirintip; Klantup, Polawat; Waraha, Atcharaphan; Sawattan, Anuchit; Thiravetyan, Paitip

2014-04-01

Air borne uptake of toluene and ethylbenzene by twelve plant species was examined. Of the twelve plant species examined, the highest toluene removal was found in Sansevieria trifasciata, while the ethylbenzene removal from air was with Chlorophytum comosum. Toluene and ethylbenzene can penetrate the plant׳s cuticle. However, the removal rates do not appear to be correlated with numbers of stomata per plant. It was found that wax of S. trifasciata and Sansevieria hyacinthoides had greater absorption of toluene and ethylbenzene, and it contained high hexadecanoic acid. Hexadecanoic acid might be involved in toluene and ethylbenzene adsorption by cuticles wax of plants. Chlorophyll fluorescence analysis or the potential quantum yield of PSII (Fv/Fm) in toluene exposed plants showed no significant differences between the control and the treated plants, whereas plants exposed to ethylbenzene showed significant differences or those parameters, specifically in Dracaena deremensis (Lemon lime), Dracaena sanderiana, Kalanchoe blossfeldiana, and Cordyline fruticosa. The Fv/Fm ratio can give insight into the ability of plants to tolerate (indoor) air pollution by volatile organic chemicals (VOC). This index can be used for identification of suitable plants for treating/sequestering VOCs in contaminated air. Copyright © 2014 Elsevier Inc. All rights reserved.

Optimization of non-thermal plasma efficiency in the simultaneous elimination of benzene, toluene, ethyl-benzene, and xylene from polluted airstreams using response surface methodology.

Science.gov (United States)

Najafpoor, Ali Asghar; Jonidi Jafari, Ahmad; Hosseinzadeh, Ahmad; Khani Jazani, Reza; Bargozin, Hasan

2018-01-01

Treatment with a non-thermal plasma (NTP) is a new and effective technology applied recently for conversion of gases for air pollution control. This research was initiated to optimize the efficient application of the NTP process in benzene, toluene, ethyl-benzene, and xylene (BTEX) removal. The effects of four variables including temperature, initial BTEX concentration, voltage, and flow rate on the BTEX elimination efficiency were investigated using response surface methodology (RSM). The constructed model was evaluated by analysis of variance (ANOVA). The model goodness-of-fit and statistical significance was assessed using determination coefficients (R 2 and R 2 adj ) and the F-test. The results revealed that the R 2 proportion was greater than 0.96 for BTEX removal efficiency. The statistical analysis demonstrated that the BTEX removal efficiency was significantly correlated with the temperature, BTEX concentration, voltage, and flow rate. Voltage was the most influential variable affecting the dependent variable as it exerted a significant effect (p < 0.0001) on the response variable. According to the achieved results, NTP can be applied as a progressive, cost-effective, and practical process for treatment of airstreams polluted with BTEX in conditions of low residence time and high concentrations of pollutants.

Assessment of genotoxicity of methyl-tert-butyl ether, benzene, toluene, ethylbenzene, and xylene to human lymphocytes using comet assay

International Nuclear Information System (INIS)

Chen, Colin S.; Hseu, You C.; Liang, Shih H.; Kuo, J.-Y.; Chen, Ssu. C.

2008-01-01

Methyl-tert-butyl ether (MTBE) is a gasoline oxygenate and antiknock additive substituting for lead alkyls currently in use worldwide. Benzene, toluene, ethylbenzene, and xylene (BTEX) are volatile monoaromatic hydrocarbons which are commonly found together in crude petroleum and petroleum products such as gasoline. The aim of this study is to evaluate the genotoxic effects of these tested chemicals in human lymphocytes. Using the alkaline comet assay, we showed that all of the tested chemicals induce DNA damage in isolated human lymphocytes. This effect could follow from the induction of DNA strands breaks. The neutral version of the test revealed that MTBE, benzene, and xylenes induce DNA double-strand breaks at 200 μM. Apart from MTBE, the spin traps, 5,5-dimethyl-pyrroline-N-oxide (DMPO) and N-tert-butyl-α-phenylnitrone (PBN) can decrease the level of DNA damage in BTEX at 200 μM. This indicated that DNA damage could result from the participation of free radicals in DNA-damaging effect, which was further supported by the fact that post-treatment of formamidopyrimidine-DNA glycosylase (Fpg), enzyme recognizing oxidized DNA purines, gave rise to a significant increase in the extent of DNA damage in cells treated with benzene, and xylene at 200 μM. The results obtained suggested that MTBE and BTEX could induce a variety type of DNA damage such as single-strand breaks (SSBs), double-strand breaks (DSBs), and oxidative base modification

Atmospheric benzene and toluene

International Nuclear Information System (INIS)

Rasmussen, R.A.; Khalil, M.A.K.

1983-01-01

Atmospheric concentrations of benzene (C 6 H 6 ) and toluene (C 7 H 8 )have been observed at nine remote locations of the world ranging in latitude from inside the arctic circle to the south pole. The observations span all seasons at each location. In the northern hemisphere it is observed that C 6 H 6 and C 7 H 8 are most abundant during winter and least abundant during summer. Based on the limited data available, such cycles are not observed in the tropics. These findings are consistent with the expected latitudinal and seasonal variations of OH radicals which cause benzene and toluene to be removed from the atmosphere. The latitude distribution shows high concentrations at mid latitude and low levels in the southern hemisphere. This finding is consistent with the present understanding that the sources of benzene and toluene are primarily anthropogenic. The observed concentration distribution and varibility are consistent with the short expected atmospheric lifetime of the order of months for benzene and days for toluene

Spatial variability in levels of benzene, formaldehyde, and total benzene, toluene, ethylbenzene and xylenes in New York City: a land-use regression study.

Science.gov (United States)

Kheirbek, Iyad; Johnson, Sarah; Ross, Zev; Pezeshki, Grant; Ito, Kazuhiko; Eisl, Holger; Matte, Thomas

2012-07-31

Hazardous air pollutant exposures are common in urban areas contributing to increased risk of cancer and other adverse health outcomes. While recent analyses indicate that New York City residents experience significantly higher cancer risks attributable to hazardous air pollutant exposures than the United States as a whole, limited data exist to assess intra-urban variability in air toxics exposures. To assess intra-urban spatial variability in exposures to common hazardous air pollutants, street-level air sampling for volatile organic compounds and aldehydes was conducted at 70 sites throughout New York City during the spring of 2011. Land-use regression models were developed using a subset of 59 sites and validated against the remaining 11 sites to describe the relationship between concentrations of benzene, total BTEX (benzene, toluene, ethylbenzene, xylenes) and formaldehyde to indicators of local sources, adjusting for temporal variation. Total BTEX levels exhibited the most spatial variability, followed by benzene and formaldehyde (coefficient of variation of temporally adjusted measurements of 0.57, 0.35, 0.22, respectively). Total roadway length within 100 m, traffic signal density within 400 m of monitoring sites, and an indicator of temporal variation explained 65% of the total variability in benzene while 70% of the total variability in BTEX was accounted for by traffic signal density within 450 m, density of permitted solvent-use industries within 500 m, and an indicator of temporal variation. Measures of temporal variation, traffic signal density within 400 m, road length within 100 m, and interior building area within 100 m (indicator of heating fuel combustion) predicted 83% of the total variability of formaldehyde. The models built with the modeling subset were found to predict concentrations well, predicting 62% to 68% of monitored values at validation sites. Traffic and point source emissions cause substantial variation in street-level exposures

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1.

Science.gov (United States)

Joshi, Geetika; Schmidt, Radomir; Scow, Kate M; Denison, Michael S; Hristova, Krassimira R

2016-09-01

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds' impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1.

Spatial variability in levels of benzene, formaldehyde, and total benzene, toluene, ethylbenzene and xylenes in New York City: a land-use regression study

Directory of Open Access Journals (Sweden)

Kheirbek Iyad

2012-07-01

Full Text Available Abstract Background Hazardous air pollutant exposures are common in urban areas contributing to increased risk of cancer and other adverse health outcomes. While recent analyses indicate that New York City residents experience significantly higher cancer risks attributable to hazardous air pollutant exposures than the United States as a whole, limited data exist to assess intra-urban variability in air toxics exposures. Methods To assess intra-urban spatial variability in exposures to common hazardous air pollutants, street-level air sampling for volatile organic compounds and aldehydes was conducted at 70 sites throughout New York City during the spring of 2011. Land-use regression models were developed using a subset of 59 sites and validated against the remaining 11 sites to describe the relationship between concentrations of benzene, total BTEX (benzene, toluene, ethylbenzene, xylenes and formaldehyde to indicators of local sources, adjusting for temporal variation. Results Total BTEX levels exhibited the most spatial variability, followed by benzene and formaldehyde (coefficient of variation of temporally adjusted measurements of 0.57, 0.35, 0.22, respectively. Total roadway length within 100 m, traffic signal density within 400 m of monitoring sites, and an indicator of temporal variation explained 65% of the total variability in benzene while 70% of the total variability in BTEX was accounted for by traffic signal density within 450 m, density of permitted solvent-use industries within 500 m, and an indicator of temporal variation. Measures of temporal variation, traffic signal density within 400 m, road length within 100 m, and interior building area within 100 m (indicator of heating fuel combustion predicted 83% of the total variability of formaldehyde. The models built with the modeling subset were found to predict concentrations well, predicting 62% to 68% of monitored values at validation sites. Conclusions Traffic and

[Studies of ozone formation potentials for benzene and ethylbenzene using a smog chamber and model simulation].

Science.gov (United States)

Jia, Long; Xu, Yong-Fu

2014-02-01

Ozone formation potentials from irradiations of benzene-NO(x) and ethylbenzene-NO(x) systems under the conditions of different VOC/NO(x) ratios and RH were investigated using a characterized chamber and model simulation. The repeatability of the smog chamber experiment shows that for two sets of ethylbenzene-NO(x) irradiations with similar initial concentrations and reaction conditions, such as temperature, relative humidity and relative light intensity, the largest difference in O3 between two experiments is only 4% during the whole experimental run. On the basis of smog chamber experiments, ozone formation of photo-oxidation of benzene and ethylbenzene was simulated in terms of the master chemical mechanism (MCM). The peak ozone values for benzene and ethylbenzene simulated by MCM are higher than the chamber data, and the difference between the MCM-simulated results and chamber data increases with increasing RH. Under the conditions of sunlight irradiations, with benzene and ethylbenzene concentrations being in the range of (10-50) x 10(-9) and NO(x) concentrations in the range of (10-100) x 10(-9), the 6 h ozone contributions of benzene and ethylbenzene were obtained to be (3.1-33) x 10(-9) and (2.6-122) x 10(-9), whereas the peak O3 contributions of benzene and ethylbenzene were (3.5-54) x 10(-9) and (3.8-164) x 10(-9), respectively. The MCM-simulated maximum incremental reactivity (MIR) values for benzene and ethylbenzene were 0.25/C and 0.97/C (per carbon), respectively. The maximum ozone reactivity (MOR) values for these two species were obtained to be 0.73/C and 1.03/C, respectively. The MOR value of benzene from MCM is much higher than that obtained by carter from SAPRC, indicating that SAPRC may underestimate the ozone formation potential of benzene.

On the origin of benzene, toluene, ethylbenzene and xylene in extra virgin olive oil.

Science.gov (United States)

Biedermann, M; Grob, K; Morchio, G

1995-04-01

Concentrations of benzene, toluene, C2-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4-10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism.

Determinação de benzeno, tolueno, etilbenzeno e xilenos em gasolina comercializada nos postos do estado do Piauí Determination of benzene, toluene, ethylbenzene and xylenes in commercial gasoline from Piaui state

Directory of Open Access Journals (Sweden)

Flamys Lena do N. Silva

2009-01-01

Full Text Available Automotive gasoline consists of a complex mixture of flammable and volatile hydrocarbons derived from crude oil with carbon numbers within the range of 4-12 and boiling points range of 30-225 ºC. Its composition varies with the kind of crude oil and the type of refinery process that they undergone. Aromatics hydrocarbons, in particular benzene, toluene, ethylbenzene and isomeric xylenes (BTEX are the toxic group constituents presents. GC-FID was employed to quantify these hydrocarbons in 50 commercial gasoline samples from Piauí state. Statistical analysis techniques, such as PCA and HCA were used to analyze the data. Moreover, several validation parameters were evaluated.

Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods

Science.gov (United States)

Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

2017-01-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products. PMID:29261711

A chromosomally based tod-luxCDABE whole-cell reporter for benzene, toluene, ethybenzene, and xylene (BTEX) sensing

International Nuclear Information System (INIS)

Applegate, B.M.; Kehrmeyer, S.R.; Sayler, G.S.

1998-01-01

A tod-luxCDABE fusion was constructed and introduced into the chromosome of Pseudomonas putida F1, yielding the strain TVA8. This strain was used to examine the induction of the tod operon when exposed to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and aqueous solutions of JP-4 jet fuel constituents. Since this system contained the complete lux cassette (luxCDABE), bacterial bioluminescence in response to putative chemical inducers of the tod operon was measured on-line in whole cells without added aldehyde substrate. There was an increasing response to toluene concentrations from 30 microg/liter to 50 mg/liter, which began to saturate at higher concentrations. The detection limit was 30 microg/liter. There was a significant light response to benzene, m- and p-xylenes, phenol, and water-soluble JP-4 jet fuel components, but there was no bioluminescence response upon exposure to o-xylene. The transposon insertion was stable and had no negative effect on cell growth

Effects of Relative Humidity on Ozone and Secondary Organic Aerosol Formation from the Photooxidation of Benzene and Ethylbenzene

Science.gov (United States)

Jia, L.; Xu, Y.

2012-12-01

The formation of ozone and secondary organic aerosol from benzene-NOx and ethylbenzene-NOx irradiations was investigated under different levels of relative humidity (RH) in a smog chamber. The results show that the increase in RH can greatly reduce the maximum O3 by the transformation of -NO2 and -ONO2-containing products into the particle phase. In benzene irradiations, the SOA number concentration increases over 26 times as RH rises from ethylbenzene irradiations, ethylglyoxal favors the formation of monohydrate, which limits the RH effects. During evaporating processes, the lost substances have similar structures for both benzene and ethylbenzene. This demonstrates that ethyl-containing substances are very stable and difficult to evaporate. For benzene some of glyoxal hydrates are left to form C-O-C and C=O-containing species like hemiacetal and acetal after evaporation, whereas for ethylbenzene, glyoxal favors cross reactions with ethylglyoxal during the evaporating process. It is concluded that the increase in RH can irreversibly enhance the yields of SOA from both benzene and ethylbenzene.

Solid-Liquid Equilibria for the Binary Mixtures 1,4-Xylene + Ethylbenzene and 1,4-Xylene + Toluene

DEFF Research Database (Denmark)

Huyghe, Raphaël; Rasmussen, Peter; Thomsen, Kaj

2004-01-01

Solid-liquid equilibrium (SLE) data for the binary mixtures 1,4-xylene + ethylbenzene, and 1,4-xylene + toluene have been measured using differential scanning calorimetry (DSC) in the temperature range from 133.15 K to 293.15 K.......Solid-liquid equilibrium (SLE) data for the binary mixtures 1,4-xylene + ethylbenzene, and 1,4-xylene + toluene have been measured using differential scanning calorimetry (DSC) in the temperature range from 133.15 K to 293.15 K....

Treatment of co-mingled benzene, toluene and TCE in groundwater.

Science.gov (United States)

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 μg/L and 500 μg/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. Copyright © 2014 Elsevier B.V. All rights reserved.

The (p, ρ, T) of (methanol + benzene) and (methanol + ethylbenzene)

International Nuclear Information System (INIS)

Naziev, Yashar M.; Shahverdiyev, Astan N.; Hasanov, Vaqif H.

2005-01-01

The (p, ρ, T) of methanol, ethylbenzene and (methanol + benzene) and (methanol + ethylbenzene) at temperatures between (290 and 500) K and pressures in the range (0.1 to 60) MPa have been measured with a magnetic suspension densimeter with an uncertainty of ±0.1%. Our measurements with methanol deviate from the literature values by less than 0.2%. The (p, ρ, T) measurements were fitted with experimental uncertainties by an empirical equation. The temperature and mole fraction dependence of the coefficients of the equation of state are presented

The oxidative conversion of toluene to benzene

NARCIS (Netherlands)

Jong, de J.G.; Batist, P.A.

1971-01-01

An oxidative reaction is described in which toluene is converted into benzene. The reaction is catalyzed by bismuth uranate. Selectivities up to 70% are obtained if toluene vapor reacts with the catalyst without O (g) being present; the catalyst becomes partially reduced, but is easily reoxidized

Instrument for benzene and toluene emission measurements of glycol regenerators

International Nuclear Information System (INIS)

Hanyecz, Veronika; Szabó, Gábor; Mohácsi, Árpád; Puskás, Sándor; Vágó, Árpád

2013-01-01

We introduce an in-field and in-explosive atmosphere useable instrument, which can measure the benzene and toluene concentration in two gas and two glycol samples produced by natural gas dehydration units. It is a two-phase, on-line gas chromatograph with a photoacoustic spectroscopy based detector. The time resolution is 10 min per cycle and the minimum detectable concentrations are 2 mg m −3 for benzene, 3 mg m −3 for toluene in natural gas, and 5 g m −3 for benzene and 6 g m −3 for toluene in glycol. Test measurements were carried out at a dehydration plant belonging to MOL Hungarian Oil and Gas Company. Benzene and toluene emissions of gas dehydration unit are calculated from the measured values based on mass balance of a glycol regenerator. The relationship between the outdoor temperature and the measured concentration was observed which is caused by temperature-dependent operation of the whole dehydration unit. Emission decreases with increase of outdoor temperature. (paper)

Direct atmospheric pressure chemical ionization-tandem mass spectrometry for the continuous real-time trace analysis of benzene, toluene, ethylbenzene, and xylenes in ambient air.

Science.gov (United States)

Badjagbo, Koffi; Picard, Pierre; Moore, Serge; Sauvé, Sébastien

2009-05-01

Real-time monitoring of benzene, toluene, ethylbenzene, and xylenes (BTEX) in ambient air is essential for the early warning detection associated with the release of these hazardous chemicals and in estimating the potential exposure risks to humans and the environment. We have developed a tandem mass spectrometry (MS/MS) method for continuous real-time determination of ambient trace levels of BTEX. The technique is based on the sampling of air via an atmospheric pressure inlet directly into the atmospheric pressure chemical ionization (APCI) source. The method is linear over four orders of magnitude, with correlation coefficients greater than 0.996. Low limits of detection in the range 1-2 microg/m(3) are achieved for BTEX. The reliability of the method was confirmed through the evaluation of quality parameters such as repeatability and reproducibility (relative standard deviation below 8% and 10%, respectively) and accuracy (over 95%). The applicability of this method to real-world samples was evaluated through measurements of BTEX levels in real ambient air samples and results were compared with a reference GC-FID method. This direct APCI-MS/MS method is suitable for real-time analysis of BTEX in ambient air during regulation surveys as well as for the monitoring of industrial processes or emergency situations.

Biodegradation of benzene by halophilic and halotolerant bacteria under aerobic conditions.

Science.gov (United States)

Nicholson, Carla A; Fathepure, Babu Z

2004-02-01

A highly enriched halophilic culture was established with benzene as the sole carbon source by using a brine soil obtained from an oil production facility in Oklahoma. The enrichment completely degraded benzene, toluene, ethylbenzene, and xylenes within 1 to 2 weeks. Also, [14C]benzene was converted to 14CO2, suggesting the culture's ability to mineralize benzene. Community structure analysis revealed that Marinobacter spp. were the dominant members of the enrichment.

Degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria

NARCIS (Netherlands)

Weelink, S.A.B.

2008-01-01

Accidental spills, industrial discharges and gasoline leakage from underground storage tanks have resulted in serious pollution of the environment with monoaromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX). High concentrations of BTEX have been detected in

Comparison of measurement methods for benzene and toluene

Science.gov (United States)

Wideqvist, U.; Vesely, V.; Johansson, C.; Potter, A.; Brorström-Lundén, E.; Sjöberg, K.; Jonsson, T.

Diffusive sampling and active (pumped) sampling (tubes filled with Tenax TA or Carbopack B) were compared with an automatic BTX instrument (Chrompack, GC/FID) for measurements of benzene and toluene. The measurements were made during differing pollution levels and different weather conditions at a roof-top site and in a densely trafficked street canyon in Stockholm, Sweden. The BTX instrument was used as the reference method for comparison with the other methods. Considering all data the Perkin-Elmer diffusive samplers, containing Tenax TA and assuming a constant uptake rate of 0.406 cm3 min-1, showed about 30% higher benzene values compared to the BTX instrument. This discrepancy may be explained by a dose-dependent uptake rate with higher uptake rates at lower dose as suggested by laboratory experiments presented in the literature. After correction by applying the relationship between uptake rate and dose as suggested by Roche et al. (Atmos. Environ. 33 (1999) 1905), the two methods agreed almost perfectly. For toluene there was much better agreement between the two methods. No sign of a dose-dependent uptake could be seen. The mean concentrations and 95% confidence intervals of all toluene measurements (67 values) were (10.80±1.6) μg m -3 for diffusive sampling and (11.3±1.6) μg m -3 for the BTX instrument, respectively. The overall ratio between the concentrations obtained using diffusive sampling and the BTX instrument was 0.91±0.07 (95% confidence interval). Tenax TA was found to be equal to Carbopack B for measuring benzene and toluene in this concentration range, although it has been proposed not to be optimal for benzene. There was also good agreement between the active samplers and the BTX instrument.

Assessing human variability in kinetics for exposures to multiple environmental chemicals: a physiologically based pharmacokinetic modeling case study with dichloromethane, benzene, toluene, ethylbenzene, and m-xylene.

Science.gov (United States)

Valcke, Mathieu; Haddad, Sami

2015-01-01

The objective of this study was to compare the magnitude of interindividual variability in internal dose for inhalation exposure to single versus multiple chemicals. Physiologically based pharmacokinetic models for adults (AD), neonates (NEO), toddlers (TODD), and pregnant women (PW) were used to simulate inhalation exposure to "low" (RfC-like) or "high" (AEGL-like) air concentrations of benzene (Bz) or dichloromethane (DCM), along with various levels of toluene alone or toluene with ethylbenzene and xylene. Monte Carlo simulations were performed and distributions of relevant internal dose metrics of either Bz or DCM were computed. Area under the blood concentration of parent compound versus time curve (AUC)-based variability in AD, TODD, and PW rose for Bz when concomitant "low" exposure to mixtures of increasing complexities occurred (coefficient of variation (CV) = 16-24%, vs. 12-15% for Bz alone), but remained unchanged considering DCM. Conversely, AUC-based CV in NEO fell (15 to 5% for Bz; 12 to 6% for DCM). Comparable trends were observed considering production of metabolites (AMET), except for NEO's CYP2E1-mediated metabolites of Bz, where an increased CV was observed (20 to 71%). For "high" exposure scenarios, Cmax-based variability of Bz and DCM remained unchanged in AD and PW, but decreased in NEO (CV= 11-16% to 2-6%) and TODD (CV= 12-13% to 7-9%). Conversely, AMET-based variability for both substrates rose in every subpopulation. This study analyzed for the first time the impact of multiple exposures on interindividual variability in toxicokinetics. Evidence indicates that this impact depends upon chemical concentrations and biochemical properties, as well as the subpopulation and internal dose metrics considered.

Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

Science.gov (United States)

Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

2007-01-01

The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

Experimental study and kinetic modeling of the thermal degradation of aromatic volatile organic compounds (benzene, toluene and xylene-para) in methane flames; Etude experimentale et modelisation cinetique de la degradation thermique des composes organiques volatils aromatiques benzenes, toluene et para-xylene dans des flammes de methane

Energy Technology Data Exchange (ETDEWEB)

Dupont, L.

2001-02-01

This study treats of the thermal degradation of a family of aromatic volatile organic compounds (VOCs) in laminar premixed methane flames at low pressure. The experimental influence of benzene, toluene and xylene-para on the structure of a reference methane flame has been studied. The molar fraction profiles of the stable and reactive, aliphatic, aromatic and cyclic species have been established by the coupling of the molecular beam sampling/mass spectroscopy technique with the gas chromatography/mass spectroscopy technique. Temperature profiles have been measured using a covered thermocouple. A detailed kinetic mechanism of oxidation of these compounds in flame conditions has been developed. Different available sub-mechanisms have been used as references: the GDF-Kin 1.0 model for the oxidation of methane and the models of Tan and Franck (1996) and of Lindstedt and Maurice (1996) in the case of benzene and toluene. In the case of para-xylene, a model has been developed because no mechanisms was available in the literature. These different mechanisms have been refined, completed or adjusted by comparing the experimental results with those obtained by kinetic modeling. The complete kinetic mechanism, comprising 156 chemical species involved in 1072 reactions allows to reproduce all the experimental observations in a satisfactory manner. The kinetic analysis of reactions velocity has permitted to determine oxidation kinetic schemes for benzene, toluene, xylene-para and for the cyclopentadienyl radical, main species at the origin of the rupture of the aromatic cycle. Reactions of recombination with the methyl radicals formed during methane oxidation, of the different aromatic or aliphatic radicals created during the oxidation of aromatics, play an important role and lead to the formation of several aromatic pollutants (ethyl-benzene for instance) or aliphatic pollutants (butadiene or penta-diene for instance) in flames. (J.S.)

Low temperature oxidation of benzene and toluene in mixture with n-decane.

Science.gov (United States)

Herbinet, Olivier; Husson, Benoit; Ferrari, Maude; Glaude, Pierre-Alexandre; Battin-Leclerc, Frédérique

2013-01-01

The oxidation of two blends, benzene/ n -decane and toluene/ n -decane, was studied in a jet-stirred reactor with gas chromatography analysis (temperatures from 500 to 1100 K, atmospheric pressure, stoichiometric mixtures). The studied hydrocarbon mixtures contained 75% of aromatics in order to highlight the chemistry of the low-temperature oxidation of these two aromatic compounds which have a very low reactivity compared to large alkanes. The difference of behavior between the two aromatic reactants is highly pronounced concerning the formation of derived aromatic products below 800 K. In the case of benzene, only phenol could be quantified. In the case of toluene, significant amounts of benzaldehyde, benzene, and cresols were also formed, as well as several heavy aromatic products such as bibenzyl, phenylbenzylether, methylphenylbenzylether, and ethylphenylphenol. A comparison with results obtained with neat n -decane showed that the reactivity of the alkane is inhibited by the presence of benzene and, to a larger extent, toluene. An improved model for the oxidation of toluene was developed based on recent theoretical studies of the elementary steps involved in the low-temperature chemistry of this molecule. Simulations using this model were successfully compared with the obtained experimental results.

The volumetric properties of (1,2-propanediol carbonate+benzene, or toluene, or styrene) binary mixtures at temperatures from T=293.15 K to T=353.15 K

International Nuclear Information System (INIS)

Wang Haijun; Wu Yonghua; Huang Jihou

2006-01-01

The densities and excess molar volumes V m E for binary liquid mixtures of (1,2-propanediol carbonate+benzene, or toluene, or ethylbenzene, or styrene) have been measured as a function of compositions using a vibrating-tube densimeter in the temperature range of (293.15 to 353.15) K and at atmospheric pressure. The V m E results were correlated using the fourth-order Redlich-Kister equation. It was found that the V m E in these systems studied increases with rising temperature

Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Shamizadeh, Mohammad; Moradian, Rostam; Astinchap, Bandar

2014-01-01

Highlights: • Co 3 O 4 nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co 3 O 4 nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared

Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Gholivand, Mohammad Bagher, E-mail: MB.Gholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba; Shamizadeh, Mohammad [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Moradian, Rostam; Astinchap, Bandar [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Technology Research Laboratory, Razi University, Kermanshah (Iran, Islamic Republic of)

2014-04-01

Highlights: • Co{sub 3}O{sub 4} nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co{sub 3}O{sub 4} nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared.

Effects of vehicle ventilation system, fuel type, and in-cabin smoking on the concentration of toluene and ethylbenzene in Pride cars

Directory of Open Access Journals (Sweden)

Masoud Rismanchian

2013-01-01

Conclusion: The ventilation condition, fuel type, and in-cabin smoking were not significantly impressive on the toluene and ethylbenzene concentrations inside the cars. However, simultaneous usage of the vehicle ventilation system and natural ventilation (windows could lead to little decrease in toluene concentration levels inside the car, while smoking consumption by passengers can increase them.

Normal and Inverse Diffusive Isotope Fractionation of Deuterated Toluene and Benzene in Aqueous Systems

DEFF Research Database (Denmark)

Rolle, Massimo; Jin, Biao

2017-01-01

and toluene. Multitracer experiments were carried out in 1-D gel dissection tubes and in a quasi-2-D flow-through porous medium. The experiments allowed us to simultaneously and directly compare the diffusive and dispersive behavior of benzene and toluene. We observed an unexpected, opposite behavior...... of the two monoaromatic hydrocarbons. Toluene showed a normal diffusive isotope effect (DC7D8/DC7H8 = 0.96) with enrichment of the nondeuterated isotopologue in the direction of the diffusive and transverse dispersive fluxes. Conversely, the measured trends for benzene indicate inverse diffusive...

Sonochemical treatment of benzene/toluene contaminated wastewater

Energy Technology Data Exchange (ETDEWEB)

Thoma, G.; Gleason, M. [Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Chemical Engineering; Popov, V. [Scientific Production Association Typhoon, Obninsk (Russian Federation). Inst. of Experimental Meterology

1998-12-31

Studies of the destruction of benzene and toluene in water were undertaken using ultrasonic irradiation in a parallel place Near Field Acoustic Processor (NAP). This magnetostrictive system is capable of degrading both benzene and toluene in a continuous stirred tank reactor configuration. The reaction kinetics were characterized by first order rate constants for the disappearance of the parent compound; these ranged from 2.7 {times} 1{sup {minus}3} to 3.7 {times} 10{sup {minus}2} mm{sup {minus}1} over an applied power density range of 0.6 to 3.6 watt mL{sup {minus}1} and target concentration of approximately 25 to 900 {micro}M. The rate constant is shown to be inversely proportional to the target compound concentration, indicating higher order reaction kinetics. The conversion efficiency for the system was characterized through the G efficiency commonly used in radiation chemistry. The G efficiency ranged between 4 {times} 10{sup {minus}5} to 2.2 {times} 10{sup {minus}4} molecules destroyed per 100 eV of electrical energy drawn from the wall outlet. These values are comparable to those of other advanced oxidation processes. Suggestions are made regarding methods to improve this technology.

Normal and Inverse Diffusive Isotope Fractionation of Deuterated Toluene and Benzene in Aqueous Systems

DEFF Research Database (Denmark)

Rolle, Massimo; Jin, Biao

2017-01-01

Diffusive isotope fractionation of organic contaminants in aqueous solution is difficult to quantify, and only a few experimental data sets are available for compounds of environmental interest. In this study, we investigate diffusive fractionation of perdeuterated and nondeuterated benzene...... and toluene. Multitracer experiments were carried out in 1-D gel dissection tubes and in a quasi-2-D flow-through porous medium. The experiments allowed us to simultaneously and directly compare the diffusive and dispersive behavior of benzene and toluene. We observed an unexpected, opposite behavior...... of the two monoaromatic hydrocarbons. Toluene showed a normal diffusive isotope effect (DC7D8/DC7H8 = 0.96) with enrichment of the nondeuterated isotopologue in the direction of the diffusive and transverse dispersive fluxes. Conversely, the measured trends for benzene indicate inverse diffusive...

Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

Directory of Open Access Journals (Sweden)

Amaury Pérez Sánchez

2017-07-01

Full Text Available Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by using the process simulator CHEMCAD® version 5.2.0, in order to determine the composition and mass flow-rate of each process involved in the production, as well as the main operating parameters of the equipment used. Two sensitivity studies were carried out: firstly, the influence of the temperature and pressure values applied at the LLV Separator on the amounts of ethyl-benzene and styrene to be obtained by the intermediate and top currents of this equipment; secondly, the influence of the operating pressure of the Distillation Column No. 1 (benzene-toluene column on the quantity of ethyl-benzene and styrene obtained at the bottom stream. The simulating software MATLAB® version 7.8.0 was used to process the results obtained. Results: Around 9234.436 kg/h of styrene is obtained in the last distillation column with 99.6% purity. Additionally, it was found that the water is the main impurity found on this stream, which represents 0.35% of the weight. Conclusions: The LLV Separator must operate at a low temperature (5 – 10 ºC and at a relatively high pressure (10 bar, whereas the Distillation Column No. 1 must work at a pressure near atmospheric (1.0 bar, or preferably under vacuum conditions in order to obtain the highest yields of styrene and ethyl-benzene.

Session 4: Study of alkyl-aromatics hydrodealkylation reaction to orient the production of benzene from the catalytic reforming process

Energy Technology Data Exchange (ETDEWEB)

Toppi, S.; Thomas, C.; Sayag, C.; Brodzki, D.; Djega-Mariadassou, G. [Universite Pierre et Marie Curie, Lab. de Reactivite de Surface, UMR CNRS 7609, 75 - Paris (France); Toppi, S.; Travers, C.; Le Peltier, F. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

2004-07-01

Due to more stringent environmental constraints, the benzene content in the gasoline decreases regularly and has been fixed to 1% since January 2001. In the same time, the demand in aromatics, benzene, toluene, and xylenes, for the petrochemistry continuously increases. The aim of this work is to study the hydrodealkylation reactions and particularly the benzene formation under reforming operating conditions, with the bifunctional industrial catalyst. It is, therefore, of great importance to determine the role of each function of the catalyst involved in the benzene production in order to orient the reaction by modification of the catalyst. n-propylbenzene transformation was investigated on each family of model catalysts and allowed us to propose a detailed scheme for the reaction on acidic and metallic sites. The identified reactions are: - on metallic sites: dehydrogenation, cyclisation and hydrogenolysis A detailed reaction scheme for this transformation has already been proposed involving the formation of cyclisation products and the existence of a common reactive adsorbate for the indene compounds and ethylbenzene; - on acidic sites: dehydrogenation, isomerization and cracking. The study of the cracking reactions coupled with measurements of the acidity of the catalyst, shows that benzene is the preferentially formed cracking product, on the Broensted sites of the catalyst, through a carbo-cationic mechanism. Conversely, ethylbenzene and toluene are formed through a 'radical' mechanism over the Lewis acid sites of alumina. As far as the cracking reaction leading to benzene is concerned, two compulsory steps were pointed out: the first one is the isomerization of n-propylbenzene to iso-propylbenzene, and the second one is the cracking of iso-propylbenzene into benzene. The increase of strong Broensted acidity over model acidic catalysts, has been correlated with a strong increase of the benzene formation rate, emphasizing the role of strong Broensted

Catabolite-mediated mutations in alternate toluene degradative pathways in Pseudomonas putida.

Science.gov (United States)

Leddy, M B; Phipps, D W; Ridgway, H F

1995-01-01

Pseudomonas putida 54g grew on mineral salts with toluene and exhibited catechol-2,3-dioxygenase (C23O) activity, indicating a meta pathway. After 10 to 15 days on toluene, nondegrading (Tol-) variants approached nearly 10% of total CFU. Auxotrophs were not detected among variants, suggesting selective loss of catabolic function(s). Variant formation was substrate dependent, since Tol- cells were observed on neither ethylbenzene, glucose, nor peptone-based media nor when toluene catabolism was suppressed by glucose. Unlike wild-type cells, variants did not grow on gasoline, toluene, benzene, ethylbenzene, benzoate, or catechol, suggesting loss of meta pathway function. Catabolic and C23O activities were restored to variants via transfer of a 78-mDa TOL-like plasmid from a wild-type Tol+ donor. Tests for reversion of variants to Tol+ were uniformly negative, suggesting possible delection or excision of catabolic genes. Deletions were confirmed in some variants by failure to hybridize with a DNA probe specific for the xylE gene encoding C23O. Cells grown on benzoate remained Tol+ but were C23O- and contained a plasmid of reduced size or were plasmid free, suggesting an alternate chromosomal catabolic pathway, also defective in variants. Cells exposed to benzyl alcohol, the initial oxidation product of toluene, accumulated > 13% variants in 5 days, even when cell division was repressed by nitrogen deprivation to abrogate selection processes. No variants formed in identical ethylbenzene-exposed controls. The results suggest that benzyl alcohol mediates irreversible defects in both a plasmid-associated meta pathway and an alternate chromosomal pathway. PMID:7642499

On-line CO, CO2 emissions evaluation and (benzene, toluene, xylene) determination from experimental burn of tropical biomass.

Science.gov (United States)

Tawfiq, Mohammed F; Aroua, Mohamed Kheireddine; Sulaiman, Nik Meriam Nik

2015-07-01

Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass. Copyright © 2015. Published by Elsevier B.V.

Velocity-dependent emission factors of benzene, toluene and C 2-benzenes of a passenger car equipped with and without a regulated 3-way catalyst

Science.gov (United States)

Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian; Mattrel, Peter

Time-resolved chemical ionization mass spectrometry (CI-MS) has been used to investigate the velocity-dependent emission factors for benzene, toluene, the C 2-benzenes (xylenes and ethyl benzene) and nitrogen monoxide of a gasoline-driven passenger car (1.4 l, model year 1995) driven with or without catalytic exhaust gas treatment. A set of seven different driving cycles - including the European Driving Cycle (EDC), the US Urban (FTP 75) and the Highway driving cycles - with a total driving time of 12,000 s have been studied. From the obtained emission data, two sets of 15,300 and 17,200 data points which represent transient driving in the velocity range of 0-150 km h -1 and in an acceleration window of -2-3 m s -2 were explored to gain velocity-dependent emission factors. The passenger car, equipped with a regulated rhodium-platinum based three-way catalyst, showed optimal conversion efficiency (>95%) for benzene in the velocity range of 60-120 km h -1. The conversion of benzene was reduced (speed and engine load (>130 km h -1). Whereas the conversion efficiency for the class of C 2-benzenes was reduced to 10%, no net conversion could be found for toluene and benzene when driven above 130 km h -1. In contrast, the benzene and toluene emissions exceeded those of the untreated exhaust gas in the velocity range of 130-150 km h -1 by 50-92% and by 10-34%, respectively. Thus, benzene and toluene were formed across the examined three-way catalyst if the engine is operated for an extended time in a fuel-rich mode (lambda<1).

Removal of benzene and toluene from a refinery waste air stream by water sorption and biotrickling filtration

Directory of Open Access Journals (Sweden)

Paolo Viotti

2015-11-01

Full Text Available The paper presents the results of an analysis of a two-stage pilot plant for the removal of toluene and benzene from the exhaust air of an industrial wastewater treatment plant (WWTP. The two-stage air process combines a water scrubber and a biotrickling filter (BTF in sequence, and treats air stripped from the liquid phase compartments of the WWTP. During the experimental period, the pilot plant treated an airflow of 600 Nm3h-1. Average concentrations of the waste air stream entering the water scrubber were 10.61 mg Nm-3 benzene and 9.26 mg Nm-3 toluene. The water scrubber obtained medium-high removal efficiencies (averages 51% and 60%, for benzene and toluene, respectively. Subsequent passage through the BTF allowed a further reduction of average concentrations, which decreased to 2.10 mg Nm-3 benzene and to 0.84 mg Nm-3 toluene, thereby allowing overall average removal efficiencies (REs of 80% and 91% for benzene and toluene, respectively. Results prove the benefits obtained from a combination of different removal technologies: water scrubbers to remove peak concentrations and soluble compounds, and BTFs to remove compounds with lower solubility, due to the biodegradation performed by microorganisms.

Quantification of benzene, toluene, ethylbenzene and o-xylene in internal combustion engine exhaust with time-weighted average solid phase microextraction and gas chromatography mass spectrometry.

Science.gov (United States)

Baimatova, Nassiba; Koziel, Jacek A; Kenessov, Bulat

2015-05-11

A new and simple method for benzene, toluene, ethylbenzene and o-xylene (BTEX) quantification in vehicle exhaust was developed based on diffusion-controlled extraction onto a retracted solid-phase microextraction (SPME) fiber coating. The rationale was to develop a method based on existing and proven SPME technology that is feasible for field adaptation in developing countries. Passive sampling with SPME fiber retracted into the needle extracted nearly two orders of magnitude less mass (n) compared with exposed fiber (outside of needle) and sampling was in a time weighted-averaging (TWA) mode. Both the sampling time (t) and fiber retraction depth (Z) were adjusted to quantify a wider range of Cgas. Extraction and quantification is conducted in a non-equilibrium mode. Effects of Cgas, t, Z and T were tested. In addition, contribution of n extracted by metallic surfaces of needle assembly without SPME coating was studied. Effects of sample storage time on n loss was studied. Retracted TWA-SPME extractions followed the theoretical model. Extracted n of BTEX was proportional to Cgas, t, Dg, T and inversely proportional to Z. Method detection limits were 1.8, 2.7, 2.1 and 5.2 mg m(-3) (0.51, 0.83, 0.66 and 1.62 ppm) for BTEX, respectively. The contribution of extraction onto metallic surfaces was reproducible and influenced by Cgas and t and less so by T and by the Z. The new method was applied to measure BTEX in the exhaust gas of a Ford Crown Victoria 1995 and compared with a whole gas and direct injection method. Copyright © 2015 Elsevier B.V. All rights reserved.

Top-down estimates of benzene and toluene emissions in Pearl River Delta and Hong Kong, China

OpenAIRE

X. Fang; M. Shao; A. Stohl; Q. Zhang; J. Zheng; H. Guo; C. Wang; M. Wang; J. Ou; R. L. Thompson; R. G. Prinn

2015-01-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and tolu...

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

Science.gov (United States)

Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

2016-03-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12-75) and 5 (2-7) Gg yr-1 for the PRD and HK, respectively, and the toluene emissions were 131 (44-218) and 6 (2-9) Gg yr-1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant) emissions in the PRD and HK in the future.

Effects of in-cabin decoration and deodorizer use on the interior concentrations of toluene and ethylbenzene in pride cars manufactured in Iran

Directory of Open Access Journals (Sweden)

Masoud Rismanchian

2014-01-01

Conclusion: Total means concentration of toluene inside the cars was higher than that of ethylbenzene. Models of the studied vehicles were not significantly affecting the concentrations of the target volatile organic compounds.

Study of hydroxylation of benzene and toluene using a micro-DBD plasma reactor

International Nuclear Information System (INIS)

Sekiguchi, H; Ando, M; Kojima, H

2005-01-01

The hydroxylation behaviour of benzene and toluene were studied using a micro-plasma reactor, where an atmospheric non-thermal plasma was generated by a dielectric barrier discharge (DBD). The results indicated that oxidation products primarily consisted of phenol and C 4 -compounds for benzene hydroxylation, whereas cresol, benzaldehyde, benzylalcohol and C 4 -compounds were detected for toluene hydroxylation. By taking into consideration the reaction mechanism in the plasma reactor, these products were classified into (1) oxidation of the aromatic ring and functional group on the ring and (2) cleavage of the aromatic ring or dissociation of the functional group on the ring

Measurement method for benzene, toluene, and xylene in the atmosphere by the gas chromatographic method

Energy Technology Data Exchange (ETDEWEB)

Shiroyama, H

1975-08-01

The chromatographic method for measuring benzene, toluene, and xylene (three isomers) in the atmosphere was evaluated using the Varian model 2740-10 gas chromatograph. As a solvent, n-hexane was most suitable, and the detection limit was improved by increasing the purity of n-hexane. The calibration curves were prepared, the recovery rate was calculated (76.0-99.4 percent), and the correlation coefficient was obtained from regression curves (r equals 0.97-0.99). Samples collected at a naphtha cracking plant, an aluminum smelting mill, a pharmaceutical plant, a carbon electrode manufacturing plant, a plywood manufacturing plant, a plastic bathtub manufacturing plant, and along a major highway were analyzed. All three substances were detected in all samples with the concentration of toluene high compared to the other two. Among xylene isomers, the concentration of p-xylene was always the lowest while m- and o-xylene varied from place to place. In the atmosphere along the highway, the benzene, toluene, and xylene determined were 0.01-0.09 ppM. No benzene, toluene, and xylene were detected in atmospheric samples used as controls.

Irradiation with benzene, toluene and phenol electron beams in aqueous solution

International Nuclear Information System (INIS)

Santoyo O, E.L.; Lopez V, H.; Vazquez A, O.; Lizama S, B.E.; Garcia F, M.

1998-01-01

It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO 2 and H 2 O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

OpenAIRE

Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

2016-01-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and ...

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

Directory of Open Access Journals (Sweden)

X. Fang

2016-03-01

Full Text Available Benzene (C6H6 and toluene (C7H8 are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD and Hong Kong (HK, which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12–75 and 5 (2–7 Gg yr−1 for the PRD and HK, respectively, and the toluene emissions were 131 (44–218 and 6 (2–9 Gg yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant emissions in the PRD and HK in the future.

Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

1998-12-31

Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

Benzene and toluene concentrations in a hemodialysis room in a medium sized South Korean city.

Science.gov (United States)

Kang, Moon-Soo; Hong, Joong-Rock; Gil, Hyo-Wook; Yang, Jong-Oh; Lee, Eun-Young; Hong, Sae-Yong; Jun, Yong-Taek; Son, Bu-Soon

2008-09-01

The current study was designed to determine whether the indoor air pollution in a hemodialysis room (HD) was different from that of other comparable areas in a hospital. Five air monitor samplers were hung on the ceiling and placed on the table in both the HD and general ward nursing stations, respectively. In addition, five samplers were placed in the nurse's breathing zone of the HD and the general ward, respectively. Ten air monitor samplers were also placed on the edge of the bed in the HD, which represented the patient's breathing zone. The levels of benzene and toluene were analyzed by GC/MS. In the general ward, the toluene concentration was significantly higher in the nurse breathing zone than that for the ceiling or table samples (p=0.001). The benzene concentration was also significantly higher in the general ward nurse breathing zone than that in the HD (p=0.006). In addition, the benzene concentrations on the table were higher at the general ward as compared to the HD (p=0.028), but there was no significant difference between the ceiling, general ward station and HD. Both the benzene and toluene concentrations in the HD appear to be more affected by the outdoor atmospheric conditions than by any potential indoor internal sources.

Substrate interactions of benzene, toluene, and para-xylene during microbial degradation by pure cultures and mixed culture aquifer slurries

International Nuclear Information System (INIS)

Alvarez, P.J.J.; Vogel, T.M.

1991-01-01

Release of petroleum hydrocarbons in the environment is a widespread occurrence. One particular concern is the contamination of drinking water sources by the toxic, water-soluble, and mobile petroleum components benzene, toluene, and xylene (BTX). Benzene, toluene, and p-xylene (BTX) were degraded by indigenous mixed cultures in sandy aquifer material and by two pure cultures isolated from the same site. Although BTX compounds have a similar chemical structure, the fate of individual BTX compounds differed when the compounds were fed to each pure culture and mixed culture aquifer slurries. The identification of substrate interactions aided the understanding of this behavior. Beneficial substrate interactions included enhanced degradation of benzene-dependent degradation of toluene and p-xylene by Arthrobacter sp. strain HCB. Detrimental substrate interactions included retardation in benzene and toluene degradation by the presence of p-xylene in both aquifer slurries and Pseudomonas incubations. The catabolic diversity of microbes in the environment precludes generalizations about the capacity of individual BTX compounds to enhance or inhibit the degradation of other BTX compounds

Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam

International Nuclear Information System (INIS)

Gonzalez Vanderhaghen, D.E.

1998-01-01

In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 μA). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

KAUST Repository

Hossain, Mohammad M.

2012-10-01

The kinetics of ethylbenzene (EB) dehydrogenation over a FeO x-meso-Al 2O 3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N 2 adsorption shows that the synthesized FeO x-meso-Al 2O 3 catalyst is mesoporous with pore size between 9 and 35nm. TPR profile indicates that iron on meso-Al 2O 3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH 3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeO x-meso-Al 2O 3 catalyst mainly gives styrene (∼99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80kJ/mol) found to be significantly lower than that of the undesired products benzene (144kJ/mol) and toluene (164kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55kJ/mol and 19kJ/mol, respectively. © 2012 Elsevier B.V.

Detection rates, trends in and factors affecting observed levels of selected volatile organic compounds in blood among US adolescents and adults.

Science.gov (United States)

Jain, Ram B

2017-12-01

Data from National Health and Nutrition Examination Survey were analyzed to evaluate detection rates, trend in and factors affecting the observed levels of 1,4-dichlorobenzene, benzene, ethylbenzene, o-xylene, styrene, toluene, and m/p-xylene among US adolescents and adults over 2005-2012. Over 2005-20102, among adolescents, detection rates declined by more than 50% for benzene, ethylbenzene, and o-xylene, and among adults, detection rates declined by more than 50% for ethylbenzene and o-xylene and by a little less than 50% for benzene. Among adults, adjusted levels of 1, 4-dichlorobenzene, benzene, ethylbenzene, o-xylene, toluene, and m/p-xylene decreased by 13.7%, 17.1%, 20%, 17.7%, 23.2%, and 18.7% respectively for every two-year survey cycle. Among adolescents, percentage decline in the levels of 1, 4-dichlorobenzene, benzene, ethylbenzene, o-xylene, styrene, toluene, and m/p-xylene was 15.2%, 21.4%, 19.3%, 16.1%, 47.8%, and 17.7% respectively for every two year survey period. The ratio of adjusted geometric means for adult smokers as compared to adult nonsmokers was 10.7 for benzene, 3.5 for ethylbenzene, 2.0 for o-xylene, 3.4 for styrene, 3.5 for toluene, and 2.2 for m/p-xylene. Among adolescents, gender did not affect the adjusted levels of any of the seven VOCs, and the order in which adjusted levels for 1, 4-dichlorobenzene by race/ethnicity was observed was: non-Hispanic white (0.038ng/mL)non-Hispanic black (0.178ng/mL) and most of the pairwise comparisons were statistically significantly different (pvs. 0.025ng/mL). For adults, gender did not affect the adjusted levels of 1, 4-dicholorobenzene, ethylbenzene, o-xylene, styrene, toluene, and m/p-xylene. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of Benzene & Toluene removal from synthetic polluted air with use of Nano photocatalyticTiO2/ ZNO process.

Science.gov (United States)

Gholami, Mitra; Nassehinia, Hamid Reza; Jonidi-Jafari, Ahmad; Nasseri, Simin; Esrafili, Ali

2014-02-05

Mono aromatic hydrocarbons (BTEX) are a group of hazardous pollutants which originate from sources such as refineries, gas, and oil extraction fields, petrochemicals and paint and glue industries.Conventional methods, including incineration, condensation, adsorption and absorption have been used for removal of VOCs. None of these methods is economical for removal of pollutants of polluted air with low to moderate concentrations. The heterogeneous photocatalytic processes involve the chemical reactions to convert pollutant to carbon dioxide and water. The aim of this paper is a comparison of Benzene & Toluene removal from synthetic polluted air using a Nano photocatalytic TiO2/ ZNO process. The X-ray diffraction (XRD) patterns showed that Nano crystals of TiO2 and ZNO were in anatase and rutile phases. Toluene & benzene were decomposed by TiO2/ ZNO Nano photocatalyst and UV radiation. Kruskal-wallis Test demonstrated that there are significant differences (pvalue UV intensity and decreasing initial concentrations. Effect of TiO2/ZNO Nano photocatalyst on benzene is less than that on toluene. In this research, Toluene & benzene removal by TiO2/ZNO and UV followed first-order reactions.

Lab-In-Syringe automation of stirring-assisted room-temperature headspace extraction coupled online to gas chromatography with flame ionization detection for determination of benzene, toluene, ethylbenzene, and xylenes in surface waters.

Science.gov (United States)

Horstkotte, Burkhard; Lopez de Los Mozos Atochero, Natalia; Solich, Petr

2018-06-22

Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V HS /V Sample of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L -1 level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L -1 were obtained in analyses of surface water. Copyright © 2018 Elsevier B.V. All rights reserved.

Liquid-liquid extraction/headspace/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene, (o-, m- and p-)xylene and styrene in olive oil using surfactant-coated carbon nanotubes as extractant.

Science.gov (United States)

Carrillo-Carrión, Carolina; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2007-11-09

BTEX-S compounds are widely distributed in the environment and can be present in different foodstuffs, including olive oil. Taking into account the risks of the exposure to these compounds, analytical methods for their determination in different matrices are mandatory. In this paper, the use of surfactant-coated multiwalled carbon nanotubes as additive in liquid-liquid extraction is applied for the determination of single-ring aromatic compounds in olive oil samples. After sample treatment, the aqueous extracts are subsequently analyzed by headspace/gas chromatography/mass spectrometry allowing the determination of BTEX-S within ca. 15 min. Each stage of the proposed LLE/HS/GC/MS configuration involves a selectivity enhancement avoiding the interference of other compounds of the sample matrix. Limits of detection were in the range 0.25 ng mL(-1) (obtained for ethylbenzene) and 0.43 ng mL(-1) (for benzene). The repeatability of the proposed method expressed as RSD varied between 1.9% (styrene) and 3.3% (benzene) (n=11).

Method development and optimization for the determination of benzene, toluene, ethylbenzene and xylenes in water at trace levels by static headspace extraction coupled to gas chromatography-barrier ionization discharge detection.

Science.gov (United States)

Pascale, Raffaella; Bianco, Giuliana; Calace, Stefania; Masi, Salvatore; Mancini, Ignazio M; Mazzone, Giuseppina; Caniani, Donatella

2018-05-04

Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 μg/L and from 0.202 to 2.452 μg/L, respectively. The recovery was between 0.74 ± 0.13 and 1.15 ± 0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC-BID is a successful method for BTEX analysis in water samples at the μg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units. Copyright © 2018. Published by Elsevier B.V.

Distinguishing Petroleum (Crude Oil and Fuel) From Smoke Exposure within Populations Based on the Relative Blood Levels of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX), Styrene and 2,5-Dimethylfuran by Pattern Recognition Using Artificial Neural Networks.

Science.gov (United States)

Chambers, D M; Reese, C M; Thornburg, L G; Sanchez, E; Rafson, J P; Blount, B C; Ruhl, J R E; De Jesús, V R

2018-01-02

Studies of exposure to petroleum (crude oil/fuel) often involve monitoring benzene, toluene, ethylbenzene, xylenes (BTEX), and styrene (BTEXS) because of their toxicity and gas-phase prevalence, where exposure is typically by inhalation. However, BTEXS levels in the general U.S. population are primarily from exposure to tobacco smoke, where smokers have blood levels on average up to eight times higher than nonsmokers. This work describes a method using partition theory and artificial neural network (ANN) pattern recognition to classify exposure source based on relative BTEXS and 2,5-dimethylfuran blood levels. A method using surrogate signatures to train the ANN was validated by comparing blood levels among cigarette smokers from the National Health and Nutrition Examination Survey (NHANES) with BTEXS and 2,5-dimethylfuran signatures derived from the smoke of machine-smoked cigarettes. Classification agreement for an ANN model trained with relative VOC levels was up to 99.8% for nonsmokers and 100.0% for smokers. As such, because there is limited blood level data on individuals exposed to crude oil/fuel, only surrogate signatures derived from crude oil and fuel were used for training the ANN. For the 2007-2008 NHANES data, the ANN model assigned 7 out of 1998 specimens (0.35%) and for the 2013-2014 NHANES data 12 out of 2906 specimens (0.41%) to the crude oil/fuel signature category.

Decomposition Characteristics of Benzene, Toluene and Xylene in an Atmospheric Pressure DC Corona Discharge II. Characteristics of Deposited By-products and Decomposition Process

OpenAIRE

SAKAI, Seiji; TAKAHASHI, Kazuhiro; SATOH, Kohki; ITOH, Hidenori

2016-01-01

Gaseous by-products and deposited material obtained from the decomposition of benzene, toluene and xylene in an atmospheric pressure DC corona discharge were minutely investigated by gas chromatograph mass spectrometry and infrared absorption spectroscopy, and the decomposition processes of benzene, toluene and xylene were estimated. It was found that carbon dioxide (CO2), carbon monoxide (CO), formic acid (HCOOH) and formic anhydride ((CHO)2) were the major gaseous by-products from benzene, ...

UV Fourier transform measurements of tropospheric O3, NO2, SO2, benzene, and toluene

International Nuclear Information System (INIS)

Vandaele, A.C.; Tsouli, A.; Carleer, M.; Colin, R.

2002-01-01

Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO 2 , SO 2 , O 3 , benzene, and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O 3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO 2 concentrations were anti-correlated to the O 3 concentrations, is expected. SO 2 also showed a pronounced dependence on car traffic. Average benzene and toluene concentrations were, respectively 1.7 ppb and between 4.4 and 6.6 pbb, but high values of toluene up to 98.8 ppb were observed. SO 2 concentrations and to a lesser extent, those of NO 2 and O 3 , were dependent on the wind direction. Ozone in Brussels has been found to be influenced by the meteorological conditions prevailing in central Europe. Comparisons with other measurements have shown that O 3 and SO 2 data are in general in good agreement, but our NO 2 concentrations seem to be generally higher. (author)

Detection of benzene and toluene gases using a midinfrared continuous-wave external cavity quantum cascade laser at atmospheric pressure.

Science.gov (United States)

Sydoryk, Ihor; Lim, Alan; Jäger, Wolfgang; Tulip, John; Parsons, Matthew T

2010-02-20

We demonstrate the application of a commercially available widely tunable continuous-wave external cavity quantum cascade laser as a spectroscopic source for the simultaneous detection of multiple gases. We measured broad absorption features of benzene and toluene between 1012 and 1063 cm(-1) (9.88 and 9.41 microm) at atmospheric pressure using an astigmatic Herriott multipass cell. Our results show experimental detection limits of 0.26 and 0.41 ppm for benzene and toluene, respectively, with a 100 m path length for these two gases.

Investigation of benzene and toluene layers on 0001 surface of graphite by means of neutron scattering

International Nuclear Information System (INIS)

Monkenbusch, M.

1981-01-01

The structures of benzene (C 6 H 6 , C 6 D 6 ) and toluene (C 6 H 5 -CH 3 , C 6 D 5 -CD 3 ) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10 -4 cm 2 /s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

Evaluation of the occupational risk for exposition to Benzene, Toluene and Xylene in a paintings industry in Bogota

International Nuclear Information System (INIS)

Rubiano D, Maria del Pilar; Marciales C, Clara; Duarte A, Martha

2002-01-01

It was determined Benzene, Toluene and Xylene (BTX) levels in air from paint manufacture assigned to Instituto Colombiano de Seguro Social with the purpose to evaluate the occupational hazard caused by the use of these solvents. These results were compared with the threshold limit value (TLV). It was selected as sampling strategy, the methodology of partial period with consecutive samples and charcoal tubes as adsorbent of solvents. The extraction was realized with carbon disulfide and it was used gas chromatography with FID as analysis method. It was found that the method is highly selective because in presence of the others ten solvents, utilized in paint manufacture, were obtained a good separation for BTX. The precision, expressed a variance coefficient, was lower than 10%, the accuracy varied between 85 and 99 % for the three solvents. The airborne concentration found was between no detectable and 55,1 mg/m 3 for benzene, 18,3 and 253 mg/m 3 for toluene and 11,8 and 122,2 mg/m 3 for xylene. The corrected TLV values for benzene, toluene and xylenes according to the brief and scale model for the ten hours shift were 1,1, 132 and 304 mg/m 3 respectively. It was found occupational risk for benzene in some workplaces; this one is worried because benzene is not used as raw material for the paint manufacture. It was determinate that exist occupational risk in almost every workplace of the industry when it is considered the mixture of the three solvents

Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation

International Nuclear Information System (INIS)

Almeida, Kelly Cristina Santana de

2006-01-01

A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 μg/L for benzene, 0.70 μg/L for toluene, and 1.54 μg/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 μg/L to 2.0 μg/L, the concentration of toluene varied from 60 Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

Benzene, toluene and p-xylene interactions and the role of microbial communities in remediation using bioventing

Energy Technology Data Exchange (ETDEWEB)

Sui, H. [Tianjin Univ., Tianjin (China). School of Chemical Engineering and Technology; Tianjin Univ., Tianjin (China). National Engineering Research Center for Distillation Technology; Li, X.G.; Jiang, B. [Tianjin Univ., Tianjin (China). National Engineering Research Center for Distillation Technology

2005-04-01

Bioventing is a promising in-situ soil remediation technology used to clean soils and groundwater contaminated by aromatic hydrocarbon components benzene, toluene and xylene (BTX). These contaminants are present at numerous hazardous waste sites. Bioventing provides enough oxygen to stimulate aerobic biodegradation by indigenous microorganisms. It is not constrained by contaminant volatility and can therefore be applied to contaminants that are readily biodegradable even if they are not highly volatile. This study examined the volatilization and biodegradation of BTX during bioventing from unsaturated soil. It focused on the occurrence of any substrate interaction and the effects of indigenous microbial inocula. The soil was inoculated with indigenous microorganisms obtained from the Dagang Oil Field in Tianjin, China. Then, different amounts of BTX were added to the soil in a stainless steel column through which carbon dioxide free air and pure nitrogen flowed. The volatilization-to-biodegradation ratios of BTX were 6:1, 2:1 and 2:1 respectively. After 3 weeks, the final concentration in the soil gas was 0.128 mg/L benzene, 0.377 mg/L toluene and 0.143 mg/L xylene. The substrate interactions that occurred were as follows: benzene and xylene degradation was accelerated while toluene was being degraded; and, the presence of xylene increased the lag period for benzene degradation. It was concluded that bioventing is an effective remediation technology for aromatic hydrocarbons and can significantly reduce the remediation time if target residual BTX concentration of 0.1 mg/L is to be reached. BTX removal becomes more significant with time, particularly when soils are inoculated with indigenous microbial communities from contaminated soil. 22 refs., 5 tabs., 7 figs.

Effective ligand functionalization of zirconium-based metal-organic frameworks for the adsorption and separation of benzene and toluene: a multiscale computational study.

Science.gov (United States)

Wu, Ying; Chen, Huiyong; Liu, Defei; Xiao, Jing; Qian, Yu; Xi, Hongxia

2015-03-18

The adsorption and separation properties of benzene and toluene on the zirconium-based frameworks UiO-66, -67, -68, and their functional analogues UiO-Phe and UiO-Me2 were studied using grand canonical Monte Carlo simulations, density functional theory, and ideal adsorbed solution theory. Remarkable higher adsorption uptakes of benzene and toluene at low pressures on UiO-Phe and -Me2 were found compared to their parent framework UiO-67. It can be ascribed to the presence of functional groups (aromatic rings and methyl groups) that significantly intensified the adsorption, majorly by reducing the effective pore size and increasing the interaction strength with the adsorbates. At high pressures, the pore volumes and accessible surfaces of the frameworks turned out to be the dominant factors governing the adsorption. In the case of toluene/benzene separation, toluene selectivities of UiOs showed a two-stage separation behavior at the measured pressure range, resulting from the greater interaction affinities of toluene at low pressures and steric hindrance effects at high pressures. Additionally, the counterbalancing factors of enhanced π delocalization and suitable pore size of UiO-Phe gave rise to the highest toluene selectivity, suggesting the ligand functionalization strategy could reach both high adsorption capacity and separation selectivity from aromatic mixtures at low concentrations.

Thermophilic biofiltration of benzene and toluene.

Science.gov (United States)

Cho, Kyung-Suk; Yoo, Sun-Kyung; Ryu, Hee Wook

2007-12-01

In the current studies, we characterized the degradation of a hot mixture of benzene and toluene (BT) gases by a thermophilic biofilter using polyurethane as packing material and high-temperature compost as a microbial source. We also examined the effect of supplementing the biofilter with yeast extract (YE). We found that YE substantially enhanced microbial activity in the thermophilic biofilter. The degrading activity of the biofilter supplied with YE was stable during long-term operation (approximately 100 d) without accumulating excess biomass. The maximum elimination capacity (1,650 g x m(-3) h(-1)) in the biofilter supplemented with YE was 3.5 times higher than that in the biofilter without YE (470 g g x m(-3) h(-1)). At similar retention times, the capacity to eliminate BT for the YE-supplemented biofilter was higher than for previously reported mesophilic biofilters. Thus, thermophilic biofiltration can be used to degrade hydrophobic compounds such as a BT mixture. Finally, 16S rDNA polymerase chain reaction-DGGE (PCR-DGGE) fingerprinting revealed that the thermophilic bacteria in the biofilter included Rubrobacter sp. and Mycobacterium sp.

Concentrations of benzene and toluene in the atmosphere of the southwestern area at the Mexico City Metropolitan Zone

Energy Technology Data Exchange (ETDEWEB)

Bravo, H.; Sosa, R.; Sanchez, P. [Universidad Autonoma de Mexico, Ciudad Universitaria (Mexico). Centro de Ciencias de la Atmosfera; Bueno, E.; Gonzalez, L. [Centro Nacional de Investigacion y Capacitacion Ambiental, Instituto Nacional de Ecologia, SEMARNAP, Mexico (Mexico)

2002-08-01

The Mexico City Metropolitan Zone (MCMZ) presents important emissions of hazardous air pollutants. It is well documented that the MCMZ suffers a critical air pollution problem due to high ozone and particulate matter concentrations. However, toxic air pollutants such as benzene and toluene have not been considered. Benzene has accumulated sufficient evidence as a human carcinogen, and the ratio benzene/toluene is an excellent indicator to evaluate control strategies efficiency. In order to evaluate the levels of these two air toxic pollutants in the MCMZ, ambient air samples were collected in canisters and analyzed with a gas chromatograph with a flame ionization detector, according to procedures described in the United States Environmental Protection Agency (USEPA) method TO-15. Quality assurance was performed collecting duplicate samples which were analyzed in replicate to quantify the precision of air-quality measurements. Three different sites located in the Southwestern area in the MCMZ were selected for the sampling: the University campus, a gas station, and a vertical condominium area, in the same neighborhood, which presents different activities. At these sites, grab air samples were collected during the morning hours (7-8 a.m.), while for the University area, 24 h integrated air samples were collected simultaneously, with grab samples. Benzene concentrations (24 h sampling) in the atmosphere around the University campus have similar present levels as in other cities of North America. Mean values in this site were about 1.7 ppb. A significant variation exists between the benzene and toluene concentrations in the studied sites, being the more critical values than those registered at the gas station (an average of 25.8 ppb and a maximum of 141 ppb of benzene). There is a fuel regulation for gasoline in Mexico, which allows a maximum of 1 percent of benzene. However, since more than 60 percent of vehicles do not have catalytic converters (models before 1991

Biological monitoring of benzene exposure for process operators during ordinary activity in the upstream petroleum industry.

Science.gov (United States)

Bråtveit, Magne; Kirkeleit, Jorunn; Hollund, Bjørg Eli; Moen, Bente E

2007-07-01

This study characterized the exposure of crude oil process operators to benzene and related aromatics during ordinary activity and investigated whether the operators take up benzene at this level of exposure. We performed the study on a fixed, integrated oil and gas production facility on Norway's continental shelf. The study population included 12 operators and 9 referents. We measured personal exposure to benzene, toluene, ethylbenzene and xylene during three consecutive 12-h work shifts using organic vapour passive dosimeter badges. We sampled blood and urine before departure to the production facility (pre-shift), immediately after the work shift on Day 13 of the work period (post-shift) and immediately before the following work shift (pre-next shift). We also measured the exposure to hydrocarbons during short-term tasks by active sampling using Tenax tubes. The arithmetic mean exposure over the 3 days was 0.042 ppm for benzene (range ethylbenzene and 0.03 ppm for xylene. Full-shift personal exposure was significantly higher when the process operators performed flotation work during the shift versus other tasks. Work in the flotation area was associated with short-term (6-15 min) arithmetic mean exposure to benzene of 1.06 ppm (range 0.09-2.33 ppm). The concentrations of benzene in blood and urine did not differ between operators and referents at any time point. When we adjusted for current smoking in regression analysis, benzene exposure was significantly associated with the post-shift concentration of benzene in blood (P = 0.01) and urine (P = 0.03), respectively. Although these operators perform tasks with relatively high short-term exposure to benzene, the full-shift mean exposure is low during ordinary activity. Some evidence indicates benzene uptake within this range of exposure.

Determination of Benzene, Toluene, and Xylene by means of an ion mobility spectrometer device using photoionization

Science.gov (United States)

Leonhardt, J. W.; Bensch, H.; Berger, D.; Nolting, M.; Baumbach, J. I.

1995-01-01

The continuous monitoring of changes on the quality of ambient air is a field of advantage of ion mobility spectrometry. Benzene, Toluene, and Xylene are substances of special interest because of their toxicity. We present an optimized drift tube for ion mobility spectrometers, which uses photo-ionization tubes to produce the ions to be analyzed. The actual version of this drift tube has a length of 45 mm, an electric field strength established within the drift tube of about 180 V/cm and a shutter-opening-time of 400 mus. With the hydrogen tube used for ionisation a mean flux of 10(exp 12) photons/sq cm s was established for the experiments described. We discuss the results of investigations on Benzene, Toluene, and Xylene in normal used gasoline SUPER. The detection limits obtained with the ion mobility spectrometer developed in co-operation are in the range of 10 ppbv in this case. Normally, charge transfer from Benzene ions to Toluene takes place. Nevertheless the simultaneous determination in mixtures is possible by a data evaluation procedure developed for this case. The interferences found between Xylene and others are rather weak. The ion mobility spectra of different concentrations of gasoline SUPER are attached as an example for the resolution and the detection limit of the instrument developed. Resolution and sensitivity of the system are well demonstrated. A hand-held portable device produced just now is to be tested for special environmental analytical problems in some industrial and scientific laboratories in Germany.

Reactions of the CN Radical with Benzene and Toluene: Product Detection and Low-Temperature Kinetics

Energy Technology Data Exchange (ETDEWEB)

Trevitt, Adam J.; Goulay, Fabien; Taatjes, Craig A.; Osborn, David L.; Leone, Stephen R.

2009-12-23

Low temperature rate coefficients are measured for the CN + benzene and CN + toluene reactions using the pulsed Laval nozzle expansion technique coupled with laser-induced fluorescence detection. The CN + benzene reaction rate coefficient at 105, 165 and 295 K is found to be relatively constant over this temperature range, 3.9 - 4.9 x 10-10 cm3 molecule-1 s-1. These rapid kinetics, along with the observed negligible temperature dependence, are consistent with a barrierless reaction entrance channel and reaction efficiencies approaching unity. The CN + toluene reaction is measured to have a slower rate coefficient of 1.3 x 10-10 cm3 molecule-1 s-1 at 105 K. At room temperature, non-exponential decay profiles are observed for this reaction that may suggest significant back-dissociation of intermediate complexes. In separate experiments, the products of these reactions are probed at room temperature using synchrotron VUV photoionization mass spectrometry. For CN + benzene, cyanobenzene (C6H5CN) is the only product recorded with no detectable evidence for a C6H5 + HCN product channel. In the case of CN + toluene, cyanotoluene (NCC6H4CH3) constitutes the only detected product. It is not possible to differentiate among the ortho, meta and para isomers of cyanotoluene because of their similar ionization energies and the ~;; 40 meV photon energy resolution of the experiment. There is no significant detection of benzyl radicals (C6H5CH2) that would suggest a H-abstraction or a HCN elimination channel is prominent at these conditions. As both reactions are measured to be rapid at 105 K, appearing to have barrierless entrance channels, it follows that they will proceed efficiently at the temperatures of Saturn?s moon Titan (~;;100 K) and are also likely to proceed at the temperature of interstellar clouds (10-20 K).

Comparative Study Between Ethylbenzene Disproportionation Reaction and its Ethylation Reaction with Ethanol over ZSM-5

KAUST Repository

Tukur, N. M.

2009-06-23

Ethylation of ethylbenzene with ethanol has been studied over ZSM-5 catalyst in a riser simulator that mimics the operation of a fluidized-bed reactor. The feed molar ratio of ethylbenzene:ethanol is 1:1. The study was carried out at 350, 400, 450, and 500°C for reaction times of 3, 5, 7, 10, 13, and 15 s. Comparisons are made between the results of the ethylbenzene ethylation reaction with that of ethylbenzene disproportionation reaction earlier reported. The effect of reaction conditions on ethylbenzene reactivity, p-diethylbenzene selectivity, total diethylbenzene (DEB) isomers selectivity, p-DEB-to-m-DEB ratio, benzene-to-DEB molar ratio, and benzene selectivity, are reported. Benzene selectivity is about 10 times more in the EB disproportion reaction as compared to its ethylation reaction with ethanol at 350°C. In addition, the results showed a p-DEB/m-DEB ratio for the EB ethylation reaction varying between 1.2-1.7, which is greater than the equilibrium values. Increase in temperature shifts the alkylation/dealkylation equilibrium towards dealkylation, thereby decreasing conversion and selectivity to DEB. © Springer Science+Business Media, LLC 2009.

Acute toxicity of toluene, hexane, xylene, and benzene to the rotifers Brachionus calyciflorus and Brachionus plicatilis

Energy Technology Data Exchange (ETDEWEB)

Ferrando, M.D.; Andreu-Moliner, E. (Univ. of Valencia (Spain))

1992-08-01

A large number of studies on the biological effects of oil pollution in the aquatic environment deal with the effects of whole crude or refined oils or their water-soluble fractions. However, low boiling, aromatic hydrocarbons, which are probably the most toxic constituents of oil, have until now not been examined in sufficient detail. Toluene, benzene and xylene, constitute a major component of various oils. They may be readily lost by weathering but are toxic in waters that are relatively stagnant and are chronically polluted. Korn et al. have stated that toluene is more toxic than many other hydrocarbons such as benzene, though the latter are more water-soluble. Report of the effects of exposure to organic solvents like hexane or toluene are still limited although organic solvents are a well-known group of neurointoxicants. Various benzene derivates continue to be used as chemical intermediates, solvents, pesticides, so on, in spite of incomplete knowledge of their chronic toxicity. The majority of toxicity studies about the effects of pollution on aquatic organisms under controlled conditions have used either fish or the cladoceran Daphnia magna and there are few studies reported using rotifers. The effects of herbicides on population variables of laboratory rotifer cultures have been investigated. Rotifers are one of the main sources of zooplankton production and they have an important ecological significance in the aquatic environment. The present work was designed to investigate the effect of short-term exposure to some petroleum derivates which might be expected to occur immediately under an oil-slick, on freshwater and brackish environment rotifers. 18 refs., 1 tab.

Tar removal from biosyngas in the biomass gasification process. (Liquid + liquid) equilibrium {water + solvent (paraxylene and methyl hexadecanoate) + model molecules of tar (benzene, toluene, phenol)}

International Nuclear Information System (INIS)

Bassil, Georgio; Mokbel, Ilham; Abou Naccoul, Ramy; Stephan, Juliette; Jose, Jacques; Goutaudier, Christelle

2012-01-01

Highlights: ► (Liquid + liquid) equilibria at atmospheric pressure. ► Solubility of benzene (or toluene or phenol) in paraxylene at (303 to 343) K. ► Solubility of benzene (or toluene or phenol) in methyl palmitate or methyl hexadecanoate at (303 to 343) K. ► Correlation of LLE using NRTL model. - Abstract: Tar is generated in the process by the condensation of the gas resulting from biomass gasification. The objective of this work is a contribution to the database on thermodynamic quantity which will be useful at the operation of tar removal from aqueous medium. With this aim, (liquid + liquid) equilibrium of {water + solvent (paraxylene and methyl hexadecanoate) + model molecules of tar (benzene, toluene, phenol)} was studied at temperatures (303.2, 323.2, and 343.2) K. The data obtained were correlated with the non-random two-liquid (NRTL) model.

Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

Directory of Open Access Journals (Sweden)

Anne B. Stephansen

2017-07-01

Full Text Available The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3 is found to undergo internal conversion in the triplet manifold within ≈100–150 fs (toluene or ≈180–200 fs (p-xylene as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.

(Liquid + liquid) equilibrium at T = 298.15 K for ternary mixtures of alkane + aromatic compounds + imidazolium-based ionic liquids

International Nuclear Information System (INIS)

Domínguez, Irene; Requejo, Patricia F.; Canosa, José; Domínguez, Ángeles

2014-01-01

Highlights: • The LLE ternary phase diagrams with 2 imidazolium-based ionic liquids were measured. • The LLE data were experimental determined at T = 298.15 K and p = 1 atm. • Mixtures of (octane or nonane) and (benzene or toluene or ethylbenzene) were studied. • LLE experimental data were correlated with NRTL and UNIQUAC thermodynamic models. - Abstract: Ionic liquids, with their unique and tunable properties, can be an advantageous alternative as extractive solvents in separation processes involving systems containing aliphatic and aromatic hydrocarbons. In this work, (liquid + liquid) equilibrium (LLE) data for the ternary systems {nonane (1) + benzene (2) + 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMim][NTf 2 ] (3)}, {octane (1) + benzene (2) + 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, [PMim][NTf 2 ] (3)}, and {nonane (1) + aromatic compound (benzene or toluene or ethylbenzene) (2) + [PMim][NTf 2 ] (3)} were determined at T = 298.15 K and atmospheric pressure. Selectivity and solute distribution ratio, derived from the equilibrium data, were used to determine if this ionic liquid can be considered as a potential solvent for the separation of aromatic compounds (benzene, toluene, and ethylbenzene) from alkanes (octane and nonane). The experimental data were satisfactorily correlated with NRTL and UNIQUAC models

Rapid determination of benzene derivatives in water samples by trace volume solvent DLLME prior to GC-FID

Energy Technology Data Exchange (ETDEWEB)

Diao, Chun Peng; Wei, Chao Hai; Feng, Chun Hua [South China Univ. of Technology, Guangzhou Higher Education Mega Center (China). College of Environmental Science and Engineering; Guangdong Regular Higher Education Institutions, Guangzhou (China). Key Lab. of Environmental Protection and Eco-Remediation

2012-05-15

An inexpensive, simple and environmentally friendly method based on dispersive liquid liquid microextraction (DLLME) for rapid determination of benzene derivatives in water samples was proposed. A significant improvement of DLLME procedure was achieved. Trace volume ethyl acetate (60 {mu}L) was exploited as dispersion solvent instead of common ones such as methanol and acetone, the volume of which was more than 0.5 mL, and the organic solvent required in DLLME was reduced to a great extent. Only 83-{mu}L organic solvent was consumed in the whole analytic process and the preconcentration procedure was less than 10 min. The advantageous approach coupled with gas chromatograph-flame ionization detector was proposed for the rapid determination of benzene, toluene, ethylbenzene and xylene isomers in water samples. Results showed that the proposed approach was an efficient method for rapid determination of benzene derivatives in aqueous samples. (orig.)

Atmospheric levels of BTEX compounds during the 2008 Olympic Games in the urban area of Beijing.

Science.gov (United States)

Liu, Junfeng; Mu, Yujing; Zhang, Yujie; Zhang, Zhimin; Wang, Xiaoke; Liu, Yanju; Sun, Zhenquan

2009-12-15

The hourly concentrations of BTEX (Benzene, Toluene, Ethylbenzene, m,p-Xylene and o-Xylene) in the urban area of Beijing were measured during July-October 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. The atmospheric BTEX were pre-concentrated on Tenax-TA tubes, and analyzed by GC-PID (Gas Chromatography with Photo Ionization Detector) after thermal desorption. During the games, the mean daytime concentrations of benzene, toluene, ethylbenzene, m,p-xylene and o-xylene were 2.37, 3.97, 1.92, 3.51 and 1.90 microg/m3, respectively, and were 52.8%, 63.9%, 56.4%, 56.8% and 46.9%, respectively lower than those after the games. The significantly positive correlation between BTEX and CO as well as the ratio of benzene/toluene suggested that the vehicle exhaust was the major source of BTEX during the whole investigated period. The extremely high ratios of ethylbenzene to m,p-xylene (E/X) were mainly observed at noontime in haze days, indicating that photochemical reactions were highly active under these typical days.

Anaerobic BTEX biodegradation linked to nitrate and sulfate reduction

International Nuclear Information System (INIS)

Dou Junfeng; Liu Xiang; Hu Zhifeng; Deng Dong

2008-01-01

Effective anaerobic BTEX biodegradation was obtained under nitrate and sulfate reducing conditions by the mixed bacterial consortium that were enriched from gasoline contaminated soil. Under the conditions of using nitrate or sulfate as reducing acceptor, the degradation rates of the six tested substrates decreased with toluene > ethylbenzene > m-xylene > o-xylene > benzene > p-xylene. The higher concentrations of BTEX were toxic to the mixed cultures and led to reduce the degradation rates of BTEX. Benzene and p-xylene were more toxic than toluene and ethylbenzene. Nitrate was a more favorable electron acceptor compared to sulfate. The measured ratios between the amount of nitrate consumed and the amount of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene degraded were 9.47, 9.26, 11.14, 12.46, 13.36 and 13.02, respectively. The measured ratios between sulfate reduction and BTEX degradation were 3.51, 4.33, 4.89, 4.81, 4.86 and 4.76, respectively, which were nearly the same to theoretical ones, and the relative error between the measured and calculated ratios was less than 10%

Computational and Experimental Study of the Structure of Diffusion Flames of Jet Fuel and Its Surrogates at Pressures up to 40 ATM

Science.gov (United States)

2012-11-21

examination of some of the aromatics show that the model captures well benzene from toluene decomposition in BF, but underpredicts styrene and ethylbenzene ...critical toluene pyrolysis products and stable soot precursors were compared with computational models using two semi-detailed chemical mechanisms... ethylbenzene , which at least one of the mechanisms reproduces quite well. The largest measured species in the incipiently sooting flame is indene, whose

Research and development for ethylbenzene production

Energy Technology Data Exchange (ETDEWEB)

Xue, Mingwei; Sun, Hongmin; Shen, Zhenhao; Zhang, Bin; Yang, Weimin [SINOPEC Shanghai Research Institute of Petrochemical Technology (China); Huan, Mingyao

2013-11-01

Ethylbenzene (EB) is important raw material for the production of styrene. Now, EB is mainly produced by the alkylation of benzene with ethylene catalyzed by zeolite in vapour phase or liquid phase. Shanghai Research Institute of Petrochemical Technology (SRIPT) began to research the catalysts for the production of ethylbenezene in 1993. With near 20 years work, three series of catalysts for the alkylation of benzene with pure ethylene, dilute ethylene and ethanol are in commerical in China. This paper mainly introduced the research and development of SRIPT for the EB production. (orig.)

Long-term phenol, cresols and BTEX monitoring in urban air.

Science.gov (United States)

Sturaro, Alberto; Rella, Rocco; Parvoli, Giorgio; Ferrara, Daniela

2010-05-01

This paper reports the results of a long-term monitoring of benzene, toluene, ethylbenzene, xylenes (BTEX), phenol and cresols in the air of Padua during a wide period of the year 2007 using two radial passive samplers (Radiello system) equipped with BTEX- and phenol-specific cartridges. Two sites were monitored, one in the industrial area and one close to the town centre. Relevant pollution episodes have been observed during both the winter and summer periods. Benzene, together with toluene, ethylbenzene and xylenes showed their maximum concentrations during the winter season, but the secondary pollutant phenol was higher than benzene for a large period of the year when the meteorological conditions blocked the pollutants in the lower layers of the atmosphere and solar radiation increased the benzene photo-oxidation process.

[Removal of volatile organic compounds in soils by soil vapor extraction (SVE)].

Science.gov (United States)

Yin, Fu-xiang; Zhang, Sheng-tian; Zhao, Xin; Feng, Ke; Lin, Yu-suo

2011-05-01

An experiment study has been carried out to investigate effects of the diameter of soil columns, the size of soil particulate and different contaminants on efficiency of simulated soil vapor extraction (SVE). Experiments with benzene, toluene, ethylbenzene and n-propylbenzene contaminated soils showed that larger bottom area/soil height (S/H) of the columns led to higher efficiency on removal of contaminants. Experiments with contaminated soils of different particulate size showed that the efficiency of SVE decreased with increases in soil particulate size, from 10 mesh to between 20 mesh and 40 mesh and removal of contaminants in soils became more difficult. Experiments with contaminated soils under different ventilation rates suggested that soil vapor extraction at a ventilation rate of 0.10 L x min(-1) can roughly remove most contaminants from the soils. Decreasing of contaminants in soils entered tailing stages after 12 h, 18 h and 48 h for benzene, toluene and ethylbenzene, respectively. Removal rate of TVOCs (Total VOCs) reached a level as high as 99.52%. The results of the experiment have indicated that molecule structure and properties of the VOCs are also important factors which have effects on removal rates of the contaminants. Increases in carbon number on the benzene ring, decreases in vapor pressure and volatile capability resulted in higher difficulties in soil decontamination. n-propylbenzene has a lower vapor pressure than toluene and ethylbenzene which led to a significant retard effect on desorption and volatilization of benzene and ethylbenzene.

Anaerobic degradation of benzene by marine sulfate-reducing bacteria

Science.gov (United States)

Musat, Florin; Wilkes, Heinz; Musat, Niculina; Kuypers, Marcel; Widdel, Friedrich

2010-05-01

Benzene, the archetypal aromatic hydrocarbon is a common constituent of crude oil and oil-refined products. As such, it can enter the biosphere through natural oil seeps or as a consequence of exploitation of fossil fuel reservoirs. Benzene is chemically very stable, due to the stabilizing aromatic electron system and to the lack of functional groups. Although the anaerobic degradation of benzene has been reported under denitrifying, sulfate-reducing and methanogenic conditions, the microorganisms involved and the initial biochemical steps of degradation remain insufficiently understood. Using marine sediment from a Mediterranean lagoon a sulfate-reducing enrichment culture with benzene as the sole organic substrate was obtained. Application of 16S rRNA gene-based methods showed that the enrichment was dominated (more than 85% of total cells) by a distinct phylotype affiliated with a clade of Deltaproteobacteria that include degraders of other aromatic hydrocarbons, such as naphthalene, ethylbenzene and m-xylene. Using benzoate as a soluble substrate in agar dilution series, several pure cultures closely related to Desulfotignum spp. and Desulfosarcina spp. were isolated. None of these strains was able to utilize benzene as a substrate and hybridizations with specific oligonucleotide probes showed that they accounted for as much as 6% of the total cells. Incubations with 13C-labeled benzene followed by Halogen in situ Hybridization - Secondary Ion Mass Spectroscopy (HISH-SIMS) analysis showed that cells of the dominant phylotype were highly enriched in 13C, while the accompanying bacteria had little or no 13C incorporation. These results demonstrate that the dominant phylotype was indeed the apparent benzene degrader. Dense-cell suspensions of the enrichment culture did not show metabolic activity toward added phenol or toluene, suggesting that benzene degradation did not proceed through anaerobic hydroxylation or methylation. Instead, benzoate was identified in

Enthalpy of mixing and heat of vaporization of ethyl acetate with benzene and toluene at 298.15 k and 308.15 k

Directory of Open Access Journals (Sweden)

K. L. Shivabasappa

2008-03-01

Full Text Available The present work was carried out in two phases. First, enthalpy of mixing was measured and then the heat of vaporization for the same mixtures was obtained. The data are useful in the design of separation equipments. From the various designs available for the experimental determination of enthalpy of mixing, and heat of vaporization, the apparatus was selected, modified and constructed. The apparatus of enthalpy of mixing was tested with a known system Benzene - i-Butyl Alcohol and the data obtained was in very good agreement with literature values. Experiments were then conducted for mixtures of Ethyl Acetate with Benzene and Toluene. The experimental data was fitted to the standard correlations and the constants were evaluated. Heat of vaporization data were obtained from a static apparatus and tested for accuracy by conducting experiments with a known system Benzene - n-Hexane and the data obtained were found to be in agreement with literature values. Experiments were then conducted to measure heat of vaporization for the mixtures of Ethyl Acetate with Benzene and Toluene. Using experimental data of enthalpy of mixing from the first phase, and heat capacity data, the heat of vaporization were calculated.

Experimental treatment of a refinery waste air stream, for BTEX removal, by water scrubbing and biotrickling on a bed of Mitilus edulis shells.

Science.gov (United States)

Torretta, Vincenzo; Collivignarelli, Maria Cristina; Raboni, Massimo; Viotti, Paolo

2015-01-01

The paper presents the results of a two-stage pilot plant for the removal of benzene, toluene, ethylbenzene and xylene (BTEX) from a waste air stream of a refinery wastewater treatment plant (WWTP). The pilot plant consisted of a water scrubber followed by a biotrickling filter (BTF). The exhausted air was drawn from the main works of the WWTP in order to prevent the free migration to the atmosphere of these volatile hazardous contaminants. Concentrations were detected at average values of 12.4 mg Nm(-3) for benzene, 11.1 mg Nm(-3) for toluene, 2.7 mg Nm(-3) for ethylbenzene and 9.5 mg Nm(-3) for xylene, with considerable fluctuation mainly for benzene and toluene (peak concentrations of 56.8 and 55.0 mg Nm(-3), respectively). The two treatment stages proved to play an effective complementary task: the water scrubber demonstrated the ability to remove the concentration peaks, whereas the BTF was effective as a polishing stage. The overall average removal efficiency achieved was 94.8% while the scrubber and BTF elimination capacity were 37.8 and 15.6 g BTEX d(-1) m(-3), respectively. This result has led to outlet average concentrations of 1.02, 0.25, 0.32 and 0.26 mg Nm(-3) for benzene, toluene, ethylbenzene and xylene, respectively. The paper also compares these final concentrations with toxic and odour threshold concentrations.

Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG) Field Demonstration Report: IRP Site 4, POL Area, Springfield ANG Base, Springfield, Ohio

National Research Council Canada - National Science Library

Reed, Dennis

2003-01-01

...) methodology to compare the approaches. Soil core composites were analyzed for trichloroethylene, gasoline-range organics, volatile petroleum hydrocarbons, benzene, toluene, ethylbenzene, and xylenes...

Impact of a new gasoline benzene regulation on ambient air pollutants in Anchorage, Alaska

Science.gov (United States)

Yano, Yuriko; Morris, Stephen S.; Salerno, Christopher; Schlapia, Anne M.; Stichick, Mathew

2016-05-01

The purpose of this study was to quantify the impact of a new U.S. Environmental Protection Agency (EPA) standard that limits the amount of benzene allowed in gasoline on ambient benzene concentrations. This new standard, together with two companion regulations that limit cold-temperature automotive emissions and the permeability of portable fuel containers, was expected to lower the levels of ambient benzene and other volatile organic compounds (VOCs) nationwide. In this study the impact of the gasoline benzene standard was evaluated in Anchorage, Alaska in a two-phase ambient air monitoring study conducted before and after the new gasoline standard was implemented. Gasoline sold by Anchorage retailers was also evaluated in each phase to determine the content of benzene and other gasoline components. The average benzene content in Anchorage gasoline was reduced by 70%, from 5.05% (w/w) to 1.53% (w/w) following the implementation of the standard. The annual mean ambient benzene concentration fell by 51%, from 0.99 ppbv in Phase 1 to 0.49 ppbv in Phase 2. Analysis suggests the change in gasoline benzene content alone reduced benzene emissions by 46%. The changes in toluene, ethylbenzene, and xylene content in gasoline between Phase 1 and 2 were relatively small and the differences in the mean ambient concentrations of these compounds between phases were modest. Our results suggest that cold winter communities in high latitude and mountainous regions may benefit more from the gasoline benzene standard because of high benzene emissions resulting from vehicle cold start and a tendency to develop atmospheric stagnation conditions in the winter.

Fabrication of CDs/CdS-TiO2 ternary nano-composites for photocatalytic degradation of benzene and toluene under visible light irradiation

Science.gov (United States)

Wang, Meng; Hua, Jianhao; Yang, Yaling

2018-06-01

An efficient cadmium sulfide quantum-dots (CdS QDs) and carbon dots (CDs) modified TiO2 photocatalyst (CdS/CDs-TiO2) was successfully fabricated. The as-prepared ternary nano-composites simultaneously improved the photo-corrosion of CdS and amplified its photocatalytic activity. The introduction of CdS QDs and CDs could enhance more absorbance of light, prevent the undesirable electron/hole recombination, and promote charge separation, which was important for the continuous formation of rad OH and rad O2- radicals. When the optimal mass ratio of CdS QDs to CDs was 3:1, above 90% degradation efficiencies were achieved for benzene within 1 h and toluene in 2 h, while that of pure TiO2 (P25), CdS QDs-TiO2, CDs-TiO2 nano-composites was around 15%. Owing to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was more difficult than benzene to carry on. The new fabricated nano-composites showed good prospective application of cleaning up refractory pollutants and the resource utilization.

Directional synthesis of ethylbenzene through catalytic transformation of lignin.

Science.gov (United States)

Fan, Minghui; Jiang, Peiwen; Bi, Peiyan; Deng, Shumei; Yan, Lifeng; Zhai, Qi; Wang, Tiejun; Li, Quanxin

2013-09-01

Transformation of lignin to ethylbenzene can provide an important bulk raw material for the petrochemical industry. This work explored the production of ethylbenzene from lignin through the directional catalytic depolymerization of lignin into the aromatic monomers followed by the selective alkylation of the aromatic monomers. For the first step, the aromatics selectivity of benzene derived from the catalytic depolymerization of lignin reached about 90.2 C-mol% over the composite catalyst of Re-Y/HZSM-5 (25). For the alkylation of the aromatic monomers in the second step, the highest selectivity of ethylbenzene was about 72.3 C-mol% over the HZSM-5 (25) catalyst. The reaction pathway for the transformation of lignin to ethylbenzene was also addressed. Present transformation potentially provides a useful approach for the production of the basic petrochemical material and development of high-end chemicals utilizing lignin as the abundant natural aromatic resource. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of nitrate addition on biorestoration of fuel-contaminated aquifer: Field demonstration

International Nuclear Information System (INIS)

Hutchins, S.R.; Downs, W.C.; Wilson, J.T.; Smith, G.B.; Kovacs, D.A.

1991-01-01

A spill of JP-4 jet fuel at the U.S. Coast Guard Air Station in Traverse City, Michigan, contaminated a water-table aquifer. An infiltration gallery (30 ft X 30 ft) was installed above a section of the aquifer containing 700 gal JP-4. Purge wells recirculated three million gallons of ground water per week through the infiltration gallery at a rate designed to raise the water table above the contaminated interval. Ground water containing ambient concentrations was first recirculated for 40 days. Concentrations of benzene in monitoring wells beneath the infiltration gallery were reduced from 760 to <1 micrograms/1. Concentrations of toluene, ethylbenzene, m,p-xylene, and o-xylene were reduced from 4500 to 17,840 to 44,2600 to 490, and 1400 to 260 micrograms/1, respectively. Average core concentrations of benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene were reduced from 0.84 to 0.032, 33 to 0.13, 18 to 0.36, 58 to 7.4, and 26 to 3.2 mg/kg, respectively. Ground water amended with nitrate (10 mg/1 nitrate-nitrogen) and nutrients was then recirculated for 76 days. Final core concentrations of benzene, toluene, ethylbenzene, m,p-xylene and o-xylene were 0.017, 0.036, 0.019, 0.059, and 0.27 mg/kg, respectively. Final aqueous concentrations were <1 micrograms/1 for benzene and toluene, 6 micrograms/1 for ethylbenzene, and 20 to 40 micrograms/1 for the xylene isomers, in good agreement with predicted values based on residual fuel content and partitioning theory. Although alkylbenzene concentrations have been substantially reduced, the test plot is still contaminated with the weathered fuel. Based on stoichiometry, approximately 10 times more nitrate was consumed than could be accounted for by BTX degradation alone, indicating that other compounds were also degraded under denitrifying conditions

Transgenic plants of Petunia hybrida harboring the CYP2E1 gene efficiently remove benzene and toluene pollutants and improve resistance to formaldehyde

Directory of Open Access Journals (Sweden)

Daoxiang Zhang

2011-01-01

Full Text Available The CYP2E1 protein belongs to the P450 enzymes family and plays an important role in the metabolism of small molecular and organic pollutants. In this study we generated CYP2E1 transgenic plants of Petunia using Agrobacterium rhizogenes K599. PCR analysis confirmed that the regenerated plants contained the CYP2E1 transgene and the rolB gene of the Ri plasmid. Southern blotting revealed the presence of multiple copies of CYP2E1 in the genome of transgenic plants. Fluorescent quantitative PCR revealed exogenous CYP2E1 gene expression in CYP2E1 transgenic plants at various levels, whereas no like expression was detected in either GUS transgenic plants or wild-types. The absorption of benzene and toluene by transgenic plants was analyzed through quantitative gas chromatography. Transgenic plants with high CYP2E1 expression showed a significant increase in absorption capacity of environmental benzene and toluene, compared to control GUS transgenic and wild type plants. Furthermore, these plants also presented obvious improved resistance to formaldehyde. This study, besides being the first to reveal that the CYP2E1 gene enhances plant resistance to formaldehyde, also furnishes a new method for reducing pollutants, such as benzene, toluene and formaldehyde, by using transgenic flowering horticultural plants.

Phylogenetic and functional diversity within toluene-degrading, sulphate-reducing consortia enriched from a contaminated aquifer.

Science.gov (United States)

Kuppardt, Anke; Kleinsteuber, Sabine; Vogt, Carsten; Lüders, Tillmann; Harms, Hauke; Chatzinotas, Antonis

2014-08-01

Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers.

Biofiltration and inhibitory interactions of gaseous benzene, toluene, xylene, and methyl tert-butyl ether.

Science.gov (United States)

Shim, Eun-Hwa; Kim, Jaisoo; Cho, Kyung-Suk; Ryu, Hee Wook

2006-05-01

This study evaluated the individual and combined removal capacities of benzene, toluene, and xylene (B, T, and X) in the presence and absence of methyl tert-butyl ether (MTBE) in a polyurethane biofilter inoculated with a BTX-degrading microbial consortium, and further examined their interactive effects in various mixtures. In addition, Polymerase chain reaction-denaturing gradient gel electrophoresis and phylogenetic analysis of 16S rRNA gene sequences were used to compare the microbial community structures found in biofilters exposed to the various gases and gas mixtures. The maximum individual elimination capacities (MECs) of B, T, and X were 200, 238, and 400 g m(-3) h(-1), respectively. There was no significant elimination of MTBE alone. Addition of MTBE decreased the MECs of B,T, and X to 75, 100, and 300 g m(-3) h(-1), respectively, indicating that benzene was most strongly inhibited by MTBE. When the three gases were mixed (B + T + X), the removal capacities of individual B, T, and X were 50, 90, and 200 g m(-3) h(-1), respectively. These capacities decreased to 40, 50, and 100 g m(-3) h(-1) when MTBE was added to the mix. The MEC of the three-gas mixture (B + T + X) was 340 g m(-3) h(-1), and that of the four-gas mixture was 200 g m(-3) h(-1). Although MTBE alone was not degraded by the biofilter, it could be co-metabolically degraded in the presence of toluene, benzene, or xylene with the MECs of 34, 23, and 14 g m(-3) h(-1), respectively. The microbial community structure analysis revealed that two large groups could be distinguished based on the presence or absence of MTBE, and many of the dominant bacteria in the consortia were closely related to bacteria isolated from aromatic hydrocarbon-contaminated sites and/ or oil wastewaters. These findings provide important new insights into biofiltration and may be used to improve the rational design of biofilters for remediation of petroleum gas-contaminated airstreams according to composition types of mixed

Optimizing BTEX biodegradation under denitrifying conditions

International Nuclear Information System (INIS)

Hutchins, S.R.

1991-01-01

Leaking underground storage tanks are a major source of ground water contamination by petroleum hydrocarbons. Gasoline and other fuels contain benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX), which are hazardous compounds, regulated by the U.S. Environmental Protection Agency (EPA). Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Michigan, were amended with selected concentrations of nutrients and one or more hydrocarbons. Toluene, ethylbenzene, m-xylene, and p-xylene, were degraded to below 5 micrograms/L when present as sole source substrates; stoichiometric calculations indicated that nitrate removal was sufficient to account for 70 to 80% of the compounds being mineralized. o-Xylene was recalcitrant when present as a sole source substrate, but was slowly degraded in the presence of the other hydrocarbons. Benzene was not degraded within one year, regardless of whether it was available as a sole source substrate or in combination with toluene, phenol, or catechol. Pre-exposure to low levels of BTEX and nutrients had variable effects, as did the addition of different concentrations of ammonia and phosphate. Nitrate concentrations as high as 500 mg/L NO3-N were slightly inhibitory. These data indicate that nitrate-mediated biodegradation of BTEX at Traverse City can occur under a variety of environmental conditions with rates relatively independent of nutrient concentrations. However, the data reaffirm that benzene is recalcitrant under strictly anaerobic conditions in these samples

Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

Science.gov (United States)

Landmeyer, James E.; Effinger, Thomas N.

2016-01-01

Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

Solid acid zeolite catalysts for benzene/ ethylene alkylation reactions

OpenAIRE

2011-01-01

Alkylation of benzene with ethylene to ethylbenzene is widely used in the petrochemical industry. Ethylbenzene is an important raw material in the petrochemical industry. It is used as feedstock for the production of styrene, an important material for plastic and rubber production.The conventional catalyst for this alkylation process is AlCl₃, which accounted for 24% of the worldwide ethylbenzene production in 2009.As utilization of this catalyst involves problems with separation, handling, s...

Biosorption removal of benzene and toluene by three dried macroalgae at different ionic strength and temperatures: Algae biochemical composition and kinetics.

Science.gov (United States)

Flores-Chaparro, Carlos E; Chazaro Ruiz, Luis Felipe; Alfaro de la Torre, Ma Catalina; Huerta-Diaz, Miguel Angel; Rangel-Mendez, Jose Rene

2017-05-15

Release of low-molecular aromatic hydrocarbons (HC) into natural waters brings severe consequences to our environment. Unfortunately very limited information is available regarding the treatment of these pollutants. This work evaluated the use of brown, green and red macroalgae biomass as biosorbents of benzene and toluene, two of the most soluble HC. Raw seaweed biomasses were completely characterized, then evaluated under different temperatures and ionic strengths to assess their potential as biosorbents and to elucidate the biosorption mechanisms involved. Brown macroalgae registered the highest removal capacities for benzene and toluene (112 and 28 mg·g -1 , respectively), and these were not affected at ionic strength < 0.6 M. Langmuir and Sips isotherm equations well described biosorption data, and the pseudo-second order model provided the best fit to the kinetics rate. Hydrocarbons are adsorbed onto the diverse chemical components of the cell wall by London forces and hydrophobic interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Light Nonaqueous-Phase Liquid Weathering at Various Fuel Release Sites

National Research Council Canada - National Science Library

Henry, Bruce

1999-01-01

...) contracted with Parsons ES to perform this fuels weathering study. Of particular interest for this study is the weathering or natural depletion of benzene, toluene, ethylbenzene, and xylenes (BTEX...

Phytoremediation removal rates of benzene, toluene, and chlorobenzene.

Science.gov (United States)

Limmer, Matt A; Wilson, Jordan; Westenberg, David; Lee, Amy; Siegman, Mark; Burken, Joel G

2018-06-07

Phytoremediation is a sustainable remedial approach, although performance efficacy is rarely reported. In this study, we assessed a phytoremediation plot treating benzene, toluene, and chlorobenzene. A comparison of the calculated phytoremediation removal rate with estimates of onsite contaminant mass was used to forecast cleanup periods. The investigation demonstrated that substantial microbial degradation was occurring in the subsurface. Estimates of transpiration indicated that the trees planted were removing approximately 240,000 L of water per year. This large quantity of water removal implies substantial removal of contaminant due to large amounts of contaminants in the groundwater; however, these contaminants extensively sorb to the soil, resulting in large quantities of contaminant mass in the subsurface. The total estimate of subsurface contaminant mass was also complicated by the presence of non-aqueous phase liquids (NAPL), additional contaminant masses that were difficult to quantify. These uncertainties of initial contaminant mass at the site result in large uncertainty in the cleanup period, although mean estimates are on the order of decades. Collectively, the model indicates contaminant removal rates on the order of 10 -2 -10 0 kg/tree/year. The benefit of the phytoremediation system is relatively sustainable cleanup over the long periods necessary due to the presence of NAPL.

Long-term study on workers occupationally exposed to ethylbenzene.

Science.gov (United States)

Bardodĕj, Z; Círek, A

1988-01-01

Ethylbenzene is synthesized from benzene; subject to catalytic dehydrogenation it yields styrene, a raw material for the production of synthetic rubber and plastics. Long-term biomonitoring of occupational ethylbenzene exposures, carried out in the past 20 years in some 200 ethylbenzene-production workers, revealed this substance to pose little hazard to human health. As it turned out, mandelic acid concentrations in these workers' urine never exceeded 3.25 mmol.l-1 and none of the exposed showed damage to hematopoiesis and/or liver tissue. Over the last 10 years no case of malignancy has been recorded in this industrial facility belonging to a larger chemical complex where the overall incidence of cancer is about 3 times the national average. Today's low-level ethylbenzene exposures would make it fully justifiable if the present-day MAC limits, both whole-shift (200 mg.m-3) and peak (1,000 mg.m-3), were to be halved, i.e. to be lowered to 100 mg.m3 and 500 mg.m3 respectively. These newly recommended limit values are no more exceeded nowadays.

Silicone sensing phase for detection of aromatic hydrocarbons in water employing near-infrared spectroscopy.

Science.gov (United States)

Albuquerque, Jackson S; Pimentel, M Fernanda; Silva, Valdinete L; Raimundo, Ivo M; Rohwedder, Jarbas J R; Pasquini, Celio

2005-01-01

The use of silicone for detection of aromatic hydrocarbons in water using near-infrared spectroscopy is proposed. A sensing phase of poly(dimethylsiloxane) (PDMS) was prepared, and a rod of this material was adapted to a transflectance probe for measurements from 850 to 1800 nm. Deionized water samples contaminated separately with known amounts of benzene, toluene, ethylbenzene, and m-xylene were used for evaluation of the PDMS sensing phase, and measurements were made in a closed reactor with constant stirring. Equilibrium states were obtained after 90, 180, 360, and 405 min for benzene, toluene, ethylbenzene, and m-xylene, respectively. The PDMS sensing phase showed a reversible response, presenting linear response ranges up to 360, 290, 100, and 80 mg L(-1), with detection limits of 8.0, 7.0, 2.6, and 3.0 mg L(-1) for benzene, toluene, ethylbenzene, and m-xylene, respectively. Reference spectra obtained with different rods showed a relative standard deviation of 0.5%, indicating repeatability in the sensing phase preparation. A relative standard deviation of 6.7% was obtained for measurements performed with six different rods, using a 52 mg L(-1) toluene aqueous solution. The sensing phase was evaluated for identification of sources of contamination of water in simulated studies, employing Brazilian gasoline type A (without ethanol), gasoline type C (with 25% of anhydrous ethanol), and diesel fuel. Principal component analysis was able to classify the water in distinct groups, contaminated by gasoline A, gasoline C, or diesel fuel.

The effect of gallium supported on mesoporous silica and its catalytic activity for oxidation of benzene, toluene and o-xylene

Energy Technology Data Exchange (ETDEWEB)

Schwanke, A.J.; Pergher, S.; Probst, L.F.D. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Balzer, R. [Universidade Federal do Parana (UFPR), PR (Brazil)

2016-07-01

Full text: Benzene, toluene and xylene (BTX) are a particular class of volatile organic compounds, which are highly toxic pollutants. In this study, samples of gallium-containing mesoporous silica (MS-Ga7% and MS-Ga11%) were synthesized and their catalytic activity in the oxidation of BTX was investigated. The physicochemical characterization by XRD, XPS, XRF, nitrogen adsorption and desorption isotherms at 77K, FTIR, SEM and TEM shows that the inclusion of gallium in the mesoporous silica structure leads to an increase in the number of oxygen vacancies in the structure of the MS-Ga system, which can result in an increase in the total and surface oxygen mobility. The results show the highest conversion for benzene (65%), with >40% for toluene and >28% for o-xylene. The high catalytic activity observed was attributed to a combination of several factors including a higher number of active sites (gallium and gallium oxide) being exposed, with a greater mobility of the active oxygen species on the surface of the catalyst promoting the catalytic activity. (author)

Irradiation with benzene, toluene and phenol electron beams in aqueous solution; Irradiacion con haces de electrones de benceno, tolueno y fenol en solucion acuosa

Energy Technology Data Exchange (ETDEWEB)

Santoyo O, E L; Lopez V, H; Vazquez A, O; Lizama S, B E; Garcia F, M [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO{sub 2} and H{sub 2}O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author.

FOOTPRINT: A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol

Science.gov (United States)

FOOTPRINT is a screening model used to estimate the length and surface area of benzene, toluene, ethylbenzene, and xylene (BTEX) plumes in groundwater, produced from a gasoline spill that contains ethanol.

Biodegradation of BTEX (Benzene, Toluene, Ethylbenzene and Xylenes) composites present in the petrochemical effluents industries; Biodegradacao dos compostos BTX (Benzeno, Tolueno e Xilenos) presentes em efluentes petroquimicos

Energy Technology Data Exchange (ETDEWEB)

Minatti, Gheise; Mello, Josiane M.M. de; Souza, Selene M.A. Guelli Ulson de; Ulson de, Antonio Augusto [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2008-07-01

The compounds BTX inside of the petrochemical effluent have presented a high potential of pollution, representing a serious risk to the environment and to the human. The great improvements in the field of biological treatment of liquid effluent were reached through the process using biofilm capable of degrading toxic compounds. The objective of this paper is to determine the degradation kinetics of BTX using biofilm. The experimental data were compared with two kinetic models, kinetic of first order and model of Michaelis-Menten. The kinetic parameters of BTX compounds were experimentally obtained in a bioreactor in batch with biomass immobilized in activated-carbon, being fed daily with solution of nutrients and BTX. For the kinetic models studied in this paper, the best performance was achieved with the model of Michaelis-Menten showing a good correlation coefficient for the three compounds. The biomass amount in these bioreactors was 49.18, 28.35 and 5.15 mg of SSV per gram of support for the toluene, benzene and o-xylene, respectively. The experimental tests showed that the biomass inside of bioreactor is capable to degrade all compounds in a time of approximately 300 minutes. (author)

Real-time monitoring of benzene, toluene, and p-xylene in a photoreaction chamber with a tunable mid-infrared laser and ultraviolet differential optical absorption spectroscopy.

Science.gov (United States)

Parsons, Matthew T; Sydoryk, Ihor; Lim, Alan; McIntyre, Thomas J; Tulip, John; Jäger, Wolfgang; McDonald, Karen

2011-02-01

We describe the implementation of a mid-infrared laser-based trace gas sensor with a photoreaction chamber, used for reproducing chemical transformations of benzene, toluene, and p-xylene (BTX) gases that may occur in the atmosphere. The system performance was assessed in the presence of photoreaction products including aerosol particles. A mid-infrared external cavity quantum cascade laser (EC-QCL)-tunable from 9.41-9.88 μm (1012-1063 cm(-1))-was used to monitor gas phase concentrations of BTX simultaneously and in real time during chemical processing of these compounds with hydroxyl radicals in a photoreaction chamber. Results are compared to concurrent measurements using ultraviolet differential optical absorption spectroscopy (UV DOAS). The EC-QCL based system provides quantitation limits of approximately 200, 200, and 600 parts in 10(9) (ppb) for benzene, toluene, and p-xylene, respectively, which represents a significant improvement over our previous work with this laser system. Correspondingly, we observe the best agreement between the EC-QCL measurements and the UV DOAS measurements with benzene, followed by toluene, then p-xylene. Although BTX gas-detection limits are not as low for the EC-QCL system as for UV DOAS, an unidentified by-product of the photoreactions was observed with the EC-QCL, but not with the UV DOAS system.

Transformation of Nitrate and Toluene in Groundwater by Sulfur Modified Iron(SMI-III)

Science.gov (United States)

Lee, W.; Park, S.; Lim, J.; Hong, U.; Kwon, S.; Kim, Y.

2009-12-01

In Korea, nitrate and benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are frequently detected together as ground water contaminants. Therefore, a system simultaneously treating both nitrate (inorganic compound) and BTEX (organic compounds) is required to utilize groundwater as a water resource. In this study, we investigated the efficiency of Sulfur Modified Iron (SMI-III) in treating both nitrate and BTEX contaminated groundwater. Based on XRD (X-Ray Diffraction) analysis, the SMI-III is mainly composed of Fe3O4, S, and Fe. A series of column tests were conducted at three different empty bed contact times (EBCTs) for each compound. During the experiments, removal efficiency for both nitrate and toluene were linearly correlated with EBCT, suggesting that SMI-III have an ability to transform both nitrate and toluene. The concentration of SO42- and oxidation/reduction potential (ORP) were also measured. After exposed to nitrate contaminated groundwater, the composition of SMI-III was changed to Fe2O3, Fe3O4, Fe, and Fe0.95S1.05. The trends of effluent sulfate concentrations were inversely correlated with effluent nitrate concentrations, while the trends of ORP values, having the minimum values of -480 mV, were highly correlated with effluent nitrate concentrations. XRD analysis before and after exposed to nitrate contaminated groundwater, sulfate production, and nitrite detection as a reductive transformation by-product of nitrate suggest that nitrate is reductively transformed by SMI-III. Interestingly, in the toluene experiments, the trends of ORP values were inversely correlated with effluent toluene concentrations, suggesting that probably degrade through oxidation reaction. Consequently, nitrate and toluene probably degrade through reduction and oxidation reaction, respectively and SMI-III could serve as both electron donor and acceptor.

Incineration of toluene and chlorobenzene in a laboratory incinerator

International Nuclear Information System (INIS)

Mao, Z.; Mcintosh, M.J.; Demirgian, J.C.

1992-01-01

This paper reports experimental results on the incineration of toluene and chlorobenzene in a small laboratory incinerator. Temperature of the incinerator, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane, toluene, benzene, chlorobenzene, hydrogen chloride and carbon monoxide in the flue gas were simultaneously analyzed. Experimental results indicate that benzene is a major product of incomplete combustion (PIC) besides carbon monoxide in the incineration of toluene and chlorobenzene, and is very sensitive to combustion conditions. This suggests that benzene is a target analyle to be monitored in full-scale incinerators

Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: A case study in Johannesburg, South Africa.

Science.gov (United States)

Moolla, Raeesa; Curtis, Christopher J; Knight, Jasper

2015-12-15

Of increasing concern is pollution by volatile organic compounds, with particular reference to five aromatic hydrocarbons (benzene, toluene, ethyl benzene and two isomeric xylenes; BTEX). These pollutants are classified as hazardous air pollutants. Due to the potential health risks associated with these pollutants, BTEX concentrations were monitored at a bus diesel-refueling bay, in Johannesburg, South Africa, using gas chromatography, coupled with a photo-ionization detector. Results indicate that o-xylene (29-50%) and benzene (13-33%) were found to be the most abundant species of total BTEX at the site. Benzene was within South African occupational limits, but above international occupational exposure limits. On the other hand, occupational concentrations of toluene, ethyl-benzene and xylenes were within national and international occupational limits throughout the monitoring period, based on 8-hour workday weighted averages. Ethyl-benzene and p-xylene concentrations, during winter, correspond to activity at the site, and thus idling of buses during refueling may elevate results. Overall, occupational air quality at the refueling bay is a matter of health concern, especially with regards to benzene exposure, and future reduction strategies are crucial. Discrepancies between national and international limit values merit further investigation to determine whether South African guidelines for benzene are sufficiently precautionary. Copyright © 2015 Elsevier B.V. All rights reserved.

Health assessment for Smith's Farm, Shepherdsville, Bullitt County, Kentucky, Region 4. CERCLIS No. KYD097267413. Preliminary report

Energy Technology Data Exchange (ETDEWEB)

1988-11-15

The Smith's Farm site is on the National Priorities List. The environmental contamination on-site consists of ethylbenzene, bis-(2-ethylhexyl)phthalate, toluene, xylene, polychlorinated biphenyls, arsenic, chromium, lead, and nickel in soil; ethylbenzene, arsenic, mercury, nickel, cadmium, and zinc in surface water; ethylbenzene, toluene, bis-(2-ethylhexyl)phthalate, polychlorinated biphenyls, arsenic, chromium, lead, and nickel in sediment; and 1,1,1-trichlorethane, vinyl chloride, isophorone, benzene, trans-1,2-dichloroethylene, trichloroethylene, xylenes, arsenic, nickel, and lead in leachate. Based on the available information, the site is considered to be of potential public health concern because of the risk to human health caused by the possibility of exposure to hazardous substances.

Cost-Effective, Ultra-Sensitive Groundwater Monitoring for Site Remediation and Management

Science.gov (United States)

2015-05-01

the In Situ Sampler (IS2). The finished product provides an account of the theory, the engineering design process, and the first field data generated...38 Figure 27. Concentrations of ethylbenzene and isopropylbenzene reported in the demonstration well using samples...Realignment and Closure BTEX benzene, toluene, ethylbenzene , and xylenes CAS Chemical Abstract Service COTS commercial off-the-shelf DC direct

Coal chemistry. 8. Reactions of tetralin with coal and with some carbon-14-containing model compounds

International Nuclear Information System (INIS)

Collins, C.J.; Raaen, V.F.; Benjamin, B.M.; Maupin, P.H.; Roark, W.H.

1979-01-01

When coal was treated with tetralin-l- 14 C at 400 0 C, small yields of α- and β-methylnaphthalenes- 14 C were observed. In order to determine the mechanism of the reaction, tetralin was heated with 14 C-labeled 1,3-diphenylpropanes (1), with 1,3-diphenylpropene (2), and with 14 C-labeled phenetoles (3). In each case methylnaphthalenes were observed, and the origins of the methyl groups were determined with carbon-14. In addition to the methylnaphthalenes, 1 and 2 also yielded toluene and ethylbenzene (after 19 h), whereas phenetole-β- 14 C (3-β- 14 C) yielded toluene (unlabeled) plus ethyl- 14 C-benzene, benzene, phenol, and a mixture of α- and β-ethyl- 14 C-naphthalenes. Crossover experiments with labeled phenetole and unlabeled ethyl p-tolyl ether proved the intramolecularity of the reaction phenetole → toluene + ethylbenzene, thus illustrating a 1,2-phenyl shift from oxygen to carbon

(Liquid + liquid) phase behavior for systems containing (aromatic + TBA + methylcyclohexane)

International Nuclear Information System (INIS)

Ghanadzadeh, H.; Ghanadzadeh, A.

2004-01-01

The determination region of solubility of TBA (tert-butanol) with representative compounds of the gasoline was investigated experimentally at temperature of 298.2 K. Type 1 (liquid + liquid) phase diagrams were obtained for (methylcyclohexane + TBA + aromatic compounds). These results were correlated simultaneously by the UNIQUAC model. The values of the interaction parameters between each pair of components in the systems were obtained for the UNIQUAC model using the experimental result. The root mean square deviation (RMSD) between the observed and calculated mole percents was 1.88 for (methylcyclohexane + TBA + benzene), 2.45 for (methylcyclohexane + TBA + toluene) and 2.86 for (methylcyclohexane + TBA + ethylbenzene). The mutual solubility of methylcyclohexane and aromatic compounds (e.g., benzene toluene and ethylbenzene (BTE)) was also investigated by the addition of TBA at temperature of 298.2 K

Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam; Radiolisis de benceno, tolueno y fenol en solucion acuosa utilizando haces de electrones

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Vanderhaghen, D E

1999-12-31

In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 {mu}A). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam; Radiolisis de benceno, tolueno y fenol en solucion acuosa utilizando haces de electrones

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Vanderhaghen, D.E

1998-12-31

In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 {mu}A). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

Occurrence and Distribution of Pharmaceutical Organic Compounds in the Groundwater Downgradient of a Landfill (Grindsted, Denmark)

DEFF Research Database (Denmark)

Holm, John V.; Rügge, Kirsten; Bjerg, Poul Løgstrup

1995-01-01

Usually landfill leachates contain specific organic compounds as BTEXs (benzene, toluene, ethylbenzene, and xylenes), chlorinated aliphatic hydrocarbons and chlorobenzenes originating from household chemicals and waste from small businesses (I). However, where industrial waste has been landfilled...

Toluene pyrolysis studies and high temperature reactions of propargyl chloride

Energy Technology Data Exchange (ETDEWEB)

Kern, R.D.; Chen, H.; Qin, Z. [Univ. of New Orleans, LA (United States)

1993-12-01

The main focus of this program is to investigate the thermal decompositions of fuels that play an important role in the pre-particle soot formation process. It has been demonstrated that the condition of maximum soot yield is established when the reaction conditions of temperature and pressure are sufficient to establish a radical pool to support the production of polyaromatic hydrocarbon species and the subsequent formation of soot particles. However, elevated temperatures result in lower soot yields which are attributed to thermolyses of aromatic ring structures and result in the bell-shaped dependence of soot yield on temperature. The authors have selected several acyclic hydrocarbons to evaluate the chemical thermodynamic and kinetic effects attendant to benzene formation. To assess the thermal stability of the aromatic ring, the authors have studied the pyrolyses of benzene, toluene, ethylbenzene, chlorobenzene and pyridine. Time-of-flight mass spectrometry (TOF) is employed to analyze the reaction zone behind reflected shock waves. Reaction time histories of the reactants, products, and intermediates are constructed and mechanisms are formulated to model the experimental data. The TOF work is often performed with use of laser schlieren densitometry (LS) to measure density gradients resulting from the heats of various reactions involved in a particular pyrolytic system. The two techniques, TOF and LS, provide independent and complementary information about ring formation and ring rupture reactions.

Relationship between hydrocarbon structure and induction of P450: effects on protein levels and enzyme activities.

Science.gov (United States)

Backes, W L; Sequeira, D J; Cawley, G F; Eyer, C S

1993-12-01

1. Treatment of male rat with the small aromatic hydrocarbons, benzene, toluene, ethylbenzene, n-propylbenzene, m-xylene, and p-xylene increased several P450-dependent activities, with ethylbenzene, m-xylene, and n-propylbenzene producing the greatest response. Hydrocarbon treatment differentially affected toluene metabolism, producing a response dependent on the metabolite monitored. In untreated rats, benzyl alcohol was the major hydroxylation product of toluene metabolism, comprising > 99% of the total metabolites formed. Hydrocarbon treatment increased the overall rate of toluene metabolism by dramatically increasing the amount of aromatic hydroxylation. Ethylbenzene, n-propylbenzene and m-xylene were the most effective inducers of aromatic hydroxylation of toluene. In contrast, production of the major toluene metabolite benzyl alcohol was increased only after treatment with m-xylene. 2. P450 2B1/2B2 levels were induced by each of the hydrocarbons examined, with the magnitude of induction increasing with increasing hydrocarbon size. P450 1A1 was also induced after hydrocarbon exposure; however, the degree of induction was smaller than that observed for P450 2B1/2B2. P450 2C11 levels were suppressed after treatment with benzene, ethylbenzene and n-propylbenzene. 3. Taken together these results display two induction patterns. The first generally corresponds to changes in the P450 2B subfamily, where activities (e.g. the aromatic hydroxylations of toluene) were most effectively induced by ethylbenzene, n-propylbenzene and m-xylene. In the second, induction was observed only after m-xylene treatment, a pattern that was found when the metabolism of the substrate was catalysed by both the P450 2B subfamily and P450 2C11. Hydrocarbons that both induced P450 2B1/2B2 and suppressed P450 2C11 (such as ethylbenzene and n-propylbenzene) showed little change in activities catalysed by both isozymes (e.g. aliphatic hydroxylation of toluene, and aniline hydroxylation

Time course for the modulation of hepatic cytochrome P450 after administration of ethylbenzene and its correlation with toluene metabolism.

Science.gov (United States)

Yuan, W; Sequeira, D J; Cawley, G F; Eyer, C S; Backes, W L

1997-03-01

The goal of the present study was to examine the time course for changes in P450 expression and hydrocarbon metabolism after acute treatment with the simple aromatic hydrocarbon ethylbenzene (EB) and to correlate these alterations with the changes observed in alkylbenzene metabolism. Male Holtzman rats were treated with a single intraperitoneal injection of EB, and the effects on specific P450-dependent activities, immunoreactive P450 isozyme levels, and RNA levels were measured at various times after injection. Toluene was used as the test alkylbenzene for examination of the EB-mediated changes on in vitro hydrocarbon metabolism. In untreated rats, toluene was metabolized almost entirely by aliphatic hydroxylation (to benzyl alcohol); however, in EB-treated rats, significant quantities of benzyl alcohol, o-cresol, and p-cresol were produced. Interestingly, 5-10 h after EB treatment, there was a 40% decrease in benzyl alcohol production. By 24 h, rates of benzyl alcohol formation returned to control levels, whereas there was a 7-fold increase in o-cresol and a greater that 50-fold increase in p-cresol production. The changes in the disposition of toluene were then correlated with changes in particular P450 isozymes. Several P450 isozymes were induced after EB administration. P450 2B1/2-dependent testosterone 16 beta-hydroxylation and P450 2B1/2-immunoreactive protein were elevated 30-fold after EB administration, reaching maxima by 24 h and remaining elevated 48 h after exposure. Changes in P450 2B1 and 2B2 RNA preceded those of the proteins. Similar results were observed with P450 1A1. P450 2E1 RNA levels were elevated after a single EB injection. However, the elevation in P450 2E1-dependent activities and immunoreactive protein levels preceded the changes in RNA, suggesting that multiple steps are affected by EB exposure. In contrast to the increases in some isozymes, P450 2C11 protein was rapidly suppressed (within the first 2-10 h) after hydrocarbon exposure

The Genome of the Toluene-Degrading Pseudomonas veronii Strain 1YdBTEX2 and Its Differential Gene Expression in Contaminated Sand.

Directory of Open Access Journals (Sweden)

Marian Morales

Full Text Available The natural restoration of soils polluted by aromatic hydrocarbons such as benzene, toluene, ethylbenzene and m- and p-xylene (BTEX may be accelerated by inoculation of specific biodegraders (bioaugmentation. Bioaugmentation mainly involves introducing bacteria that deploy their metabolic properties and adaptation potential to survive and propagate in the contaminated environment by degrading the pollutant. In order to better understand the adaptive response of cells during a transition to contaminated material, we analyzed here the genome and short-term (1 h changes in genome-wide gene expression of the BTEX-degrading bacterium Pseudomonas veronii 1YdBTEX2 in non-sterile soil and liquid medium, both in presence or absence of toluene. We obtained a gapless genome sequence of P. veronii 1YdBTEX2 covering three individual replicons with a total size of 8 Mb, two of which are largely unrelated to current known bacterial replicons. One-hour exposure to toluene, both in soil and liquid, triggered massive transcription (up to 208-fold induction of multiple gene clusters, such as toluene degradation pathway(s, chemotaxis and toluene efflux pumps. This clearly underlines their key role in the adaptive response to toluene. In comparison to liquid medium, cells in soil drastically changed expression of genes involved in membrane functioning (e.g., lipid composition, lipid metabolism, cell fatty acid synthesis, osmotic stress response (e.g., polyamine or trehalose synthesis, uptake of potassium and putrescine metabolism, highlighting the immediate response mechanisms of P. veronii 1YdBTEX2 for successful establishment in polluted soil.

Experimental and kinetic modeling investigation of rich premixed toluene flames doped with n-butanol.

Science.gov (United States)

Li, Yuyang; Yuan, Wenhao; Li, Tianyu; Li, Wei; Yang, Jiuzhong; Qi, Fei

2018-04-25

n-Butanol is a promising renewable biofuel and has a lot of advantages as a gasoline additive compared with ethanol. Though the combustion of pure n-butanol has been extensively investigated, the chemical structures of large hydrocarbons doped with n-butanol, especially for aromatic fuels, are still insufficiently understood. In this work, rich premixed toluene/n-butanol/oxygen/argon flames were investigated at 30 Torr with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The blending ratio of n-butanol was varied from 0 to 50%, while the equivalence ratio was maintained at a quite rich value (1.75) for the purpose of studying the influence of n-butanol on the aromatic growth process. Flame species including radicals, reactive molecules, isomers and polycyclic aromatic hydrocarbons (PAHs) were identified and their mole fraction profiles were measured. A kinetic model of toluene/n-butanol combustion was developed from our recently reported toluene and n-butanol models. It is observed that the production of most toluene decomposition products and larger aromatics was suppressed as the blending ratio of n-butanol increases. Meanwhile, the addition of n-butanol generally enhanced the formation of most observed C2-C4 hydrocarbons and C1-C4 oxygenated species. The rate of production (ROP) analysis and experimental observations both indicate that the interaction between toluene and n-butanol in their decomposition processes mainly occurs at the formation of small intermediates, e.g. acetylene and methyl. In particular, the interaction between toluene and n-butanol in methyl formation influences the formation of large monocyclic aromatics such as ethylbenzene, styrene and phenylacetylene, making their maximum mole fractions decay slowly upon increasing the blending ratio of n-butanol compared with toluene and benzyl. The increase of the blending ratio of n-butanol reduces the formation of key PAH precursors such as benzyl, fulvenallenyl

EFFECT OF BTEX ON THE DEGRADATION OF MTBE AND TBA BY MIXED BACTERIAL CONSORTIUM

Science.gov (United States)

Methyl tert-butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Tertiary butyl alcohol (TBA) is a prevalent intermediate of MTBE degradation. Therefore, there is a significant p...

SPATIAL AND TEMPORAL VARIABILITY IN ACROLEIN AND SELECT VOLATILE ORGANIC COMPOUNDS IN DETROIT, MICHIGAN

Science.gov (United States)

The variability in outdoor concentrations of acrolein, benzene, toluene, ethylbenzene and xylenes (BTEX), and 1,3-butadiene was examined for data measured during summer 2004 of the Detroit Exposure and Aerosol Research Study (DEARS). Results for acrolein indicated no significant...

IN VITRO CYTOTOXICITY OF BTEX METABOLITES IN HELA CELL LINES

Science.gov (United States)

Fuel leakage from underground storage tanks is a major source of groundwater contamination. Although the toxicity of regulated compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) are well recognized, the cytotoxicity of their metabolites has not been studied exte...

Coke burning behavior of a catalyst of ZSM-5/ZSM-11 co-crystallized zeolite in the alkylation of benzene with FCC off-gas to ethylbenzene

Energy Technology Data Exchange (ETDEWEB)

Song, Yi; Zhai, Yuchun [Northeastern University, Shenyang, 110006 (P. R. China); Liu, Shenglin; Wang, Qingxia; Xu, Longya [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, P. O. Box 110, Dalian 116023 (P. R. China)

2006-04-15

Since the commercialization of ethylbenzene production via alkylation of benzene with the dilute ethene in FCC off-gas over a ZSM-5/ZSM-11 co-crystallized zeolite catalyst in China, the catalyst has been regenerated several times and showed good regeneration performance. During the alkylation process, the catalytic activity decreases, some of the catalyst pores are blocked and the acid centers are partly covered by coke deposition. Influence of the factors such as catalyst particle size, temperature, etc. on the burning rate of the coke was investigated by the TG technique, and a rate equation for coke burning on the ZSM-5/ZSM-11 co-crystallized catalyst was established. (author)

Exploring the C-X…π Halogen Bonding Motif: An Infrared and Raman Study of the Complexes of CF3X (X = Cl, Br and I with the Aromatic Model Compounds Benzene and Toluene

Directory of Open Access Journals (Sweden)

Wouter A. Herrebout

2013-06-01

Full Text Available The formation of halogen bonded complexes formed between the trifluorohalomethanes CF3Cl, CF3Br and CF3I and the Lewis bases benzene and toluene at temperatures below 150K was investigated using FTIR and Raman spectroscopy. Experiments using liquid krypton as solvent show that for both CF3Br and CF3I substantial fractions of the monomers can be involved in 1:1 complexes. In addition, weak absorptions illustrating the formation of 2:1 complexes between CF3I and benzene are observed. Using spectra recorded at temperatures between 120 and 140 K, observed information on the relative stability was obtained for all complexes by determining the complexation enthalpies in solution. The resulting values for CF3Br.benzene, CF3I.benzene and (CF3I2.benzene are −6.5(3, −7.6(2 and −14.5(9 kJ mol−1. The values for CF3Br.toluene and CF3I.toluene are −6.2(5 and −7.4(5 kJ mol−1. The experimental complexation enthalpies are compared with theoretical data obtained by combining results from MP2/aug-cc-pVDZ(-PP and MP2/aug-cc-pVTZ(-PP ab initio calculations, from statistical thermodynamical calculations and from Monte Carlo Free Energy Perturbation simulations. The data are also compared with results derived for other C-X···π halogen bonded complexes involving unsaturated Lewis bases such as ethene and ethyne.

Extraction of aromatics from naphtha with ionic liquids

NARCIS (Netherlands)

Meindersma, G.W.

2005-01-01

The objective of this study was the development of a separation technology for the selective recovery and purification of aromatic compounds benzene, toluene, ethylbenzene and xylenes (BTEX) from liquid ethylene cracker feeds. Most ethylene cracker feeds contain 10 ¿ 25% of aromatic components,

Degradation of BTEX by anaerobic bacteria: physiology and application

NARCIS (Netherlands)

Weelink, S.A.B.; Eekert, van M.H.A.; Stams, A.J.M.

2010-01-01

Pollution of the environment with aromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX) is often observed. The cleanup of these toxic compounds has gained much attention in the last decades. In situ bioremediation of aromatic hydrocarbons contaminated soils and

MTBE BIOREMEDIATION WITH BIONETS CONTAINING ISOLITE®, PM1, SOLID OXYGEN SOURCE (SOS) OR AIR

Science.gov (United States)

MTBE, a gasoline additive, is a persistent and foul tasting contaminant that is more mobile in groundwater than BTEX (benzene, toluene, ethylbenzene, xylenes). It is turning up at many American crossroads. The objective of this well controlled study was to determine if biological...

MTBE BIOREMEDIATION WITH BIONETS(TM) CONTAINING ISOLITE, PM1, SOLD OXYGEN SOURCE (SOS) OR AIR

Science.gov (United States)

MTBE, a gasoline additive, is a persistent and foul tasting contaminant that is more mobile in groundwater than BTEX (benzene, toluene, ethylbenzene, xylenes). It is turning up at many American crossroads. The objective of this well controlled study was to determine if biological...

Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge.

Science.gov (United States)

Wang, Shizong; Yang, Qi; Bai, Zhiyong; Wang, Shidong; Wang, Yeyao; Nowak, Karolina M

2015-01-01

The acclimation of aerobic-activated sludge for degradation of benzene derivatives was investigated in batch experiments. Phenol, benzoic acid, toluene, aniline and chlorobenzene were concurrently added to five different bioreactors which contained the aerobic-activated sludge. After the acclimation process ended, the acclimated phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic-activated sludge were used to explore the co-metabolic degradation activities of trichloroethylene (TCE). Monod equation was employed to simulate the kinetics of co-metabolic degradation of TCE by benzene derivative-grown sludge. At the end of experiments, the mixed microbial communities grown under different conditions were identified. The results showed that the acclimation periods of microorganisms for different benzene derivatives varied. The maximum degradation rates of TCE for phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic sludge were 0.020, 0.017, 0.016, 0.0089 and 0.0047 mg g SS(-1) h(-1), respectively. The kinetic of TCE degradation in the absence of benzene derivative followed Monod equation well. Also, eight phyla were observed in the acclimated benzene derivative-grown aerobic sludge. Each of benzene derivative-grown aerobic sludge had different microbial community composition. This study can hopefully add new knowledge to the area of TCE co-metabolic by mixed microbial communities, and further the understanding on the function and applicability of aerobic-activated sludge.

[Chemical hazards when working with solvent glues].

Science.gov (United States)

Domański, Wojciech; Makles, Zbigniew

2012-01-01

Solvent glues are used in a wide variety of industries, e.g., textile, footwear and rubber. The problem of workers' exposure to solvent vapors is rarely tackled within the area of occupational safety and health in small and medium-sized enterprises. In order to assess exposure to solvents, organic solvents emitted by glues were identified in the samples of workplace air. The concentration of acetone, benzene, cyclohexane, ethylbenzene, n-hexane, methylcyclohexane, butyl acetate and toluene were determined. The obtained results evidenced the presence of cyclohexane, ethylbenzene, ethylcyclohexane, heptane, n-hexane, o-xylene, methylcyclohexane, methylcyclopentane, butyl acetate and toluene in workplace air. The concentration of those compounds in workplace air was low, usually below 0.15 of MAC. At some workstations the presence of benzene was also observed. Occupational risk was assessed at workstations where gluing took place. It showed that the risk at those workstations was medium or low.

Benzene from Traffic

DEFF Research Database (Denmark)

Palmgren, F.; Berkowicz, R.; Skov, H.

The measurements of benzene showed very clear decreasing trends in the air concentrations and the emissions since 1994. At the same time the measurements of CO and NOx also showed a decreasing trend, but not so strong as for benzene. The general decreasing trend is explained by the increasing...... number of petrol vehicles with three way catalysts, 60-70% in 1999. The very steep decreasing trend for benzene at the beginning of the period from 1994 was explained by the combination of more catalyst vehicles and reduced benzene content in Danish petrol. The total amount of aromatics in petrol......, including toluene, increased only weakly. The analyses of air concentrations were confirmed by analyses of petrol sold in Denmark. The concentration of benzene at Jagtvej in Copenhagen is still in 1998 above the expected new EU limit value, 5 µg/m3 as annual average. However, the reduced content of benzene...

MICROBIAL ANALYSIS OF MTBE, BTEX BIOREMEDIATION: BIONETS CONTAINING PM1, SOS, ISOLITE.

Science.gov (United States)

MTBE and BTEX (benzene, toluene, ethylbenzene, and xylene) are major problems of many sites in the United States. The objective of this study was to determine if biologically active in-situ BioNets could bioremediation MTBE and BTEX contaminated groundwater. Seven BioNets were ...

BTEX AND MTBE BIOREMEDIATION: BIONETS™ CONTAINING SOS, PM1 AND ISOLITE®

Science.gov (United States)

MTBE and BTEX (benzene, toluene, ethylbenzene, and xylenes) are major problems of many sites in the United States. The objective of this study was to determine if biologically active in situ BioNets could bioremediate MTBE and BTEX contaminated groundwater. Seven BioNets w...

MICROBIAL ANALYSIS OF MTBE, BTEX BIOREMEDIATION: BIONETS(TM) CONTAINING PM1, SOS, ISOLITE (R)

Science.gov (United States)

MTBE and BTEX (benzene, toluene, ethylbenzene, and xylene) are major problems of many sites in the United States. The objective of this study was to determine if biologically active in-situ BioNets could bioremediation MTBE and BTEX contaminated groundwater. Seven BioNets were ...

MICROBIAL ANALYSIS OF MTBE, BTEX BIOREMEDIATION: BIONETS CONTAINING PM1, SOS, ISOLITE�

Science.gov (United States)

MTBE and BTEX (benzene, toluene, ethylbenzene, and xylene) are major problems of many sites in the United States. The objective of this study was to determine if biologically active in-situ BioNets could bioremediate MTBE and BTEX contaminated groundwater. Seven BioNets were plac...

The conversion of BTEX compounds by single and defined mixed cultures to medium-chain-length polyhydroxyalkanoate.

Science.gov (United States)

Nikodinovic, Jasmina; Kenny, Shane T; Babu, Ramesh P; Woods, Trevor; Blau, Werner J; O'Connor, Kevin E

2008-09-01

Here, we report the use of petrochemical aromatic hydrocarbons as a feedstock for the biotechnological conversion into valuable biodegradable plastic polymers--polyhydroxyalkanoates (PHAs). We assessed the ability of the known Pseudomonas putida species that are able to utilize benzene, toluene, ethylbenzene, p-xylene (BTEX) compounds as a sole carbon and energy source for their ability to produce PHA from the single substrates. P. putida F1 is able to accumulate medium-chain-length (mcl) PHA when supplied with toluene, benzene, or ethylbenzene. P. putida mt-2 accumulates mcl-PHA when supplied with toluene or p-xylene. The highest level of PHA accumulated by cultures in shake flask was 26% cell dry weight for P. putida mt-2 supplied with p-xylene. A synthetic mixture of benzene, toluene, ethylbenzene, p-xylene, and styrene (BTEXS) which mimics the aromatic fraction of mixed plastic pyrolysis oil was supplied to a defined mixed culture of P. putida F1, mt-2, and CA-3 in the shake flasks and fermentation experiments. PHA was accumulated to 24% and to 36% of the cell dry weight of the shake flask and fermentation grown cultures respectively. In addition a three-fold higher cell density was achieved with the mixed culture grown in the bioreactor compared to shake flask experiments. A run in the 5-l fermentor resulted in the utilization of 59.6 g (67.5 ml) of the BTEXS mixture and the production of 6 g of mcl-PHA. The monomer composition of PHA accumulated by the mixed culture was the same as that accumulated by single strains supplied with single substrates with 3-hydroxydecanoic acid occurring as the predominant monomer. The purified polymer was partially crystalline with an average molecular weight of 86.9 kDa. It has a thermal degradation temperature of 350 degrees C and a glass transition temperature of -48.5 degrees C.

Excess molar volumes and refractive indices of (methoxybenzene+benzene, or toluene, or o-xylene, or m-xylene, or p-xylene, or mesitylene) binary mixtures between T=(288.15 to 303.15)K

International Nuclear Information System (INIS)

Al-Kandary, Jasem A.; Al-Jimaz, Adel S.; Abdul-Latif, Abdul-Haq M.

2006-01-01

Densities ρ and refractive indices n D for (anisole+benzene, or toluene, or o-xylene, or m-xylene or p-xylene or mesitylene) binary mixtures over the entire range of mole fraction, at temperatures (288.15, 293.15, 298.15, and 303.15)K and atmospheric pressure, have been measured. The excess molar volume V E and molar refraction deviation ΔR m , have been calculated and fitted to the Redlich-Kister polynomial relation to estimate the binary coefficients and standard errors. The excess molar volumes are positive for (anisole+mesitylene) binary mixtures and negative for (anisole+benzene, or toluene, or xylene isomers) binary mixtures at various temperatures. Partial molar volumes V-bar i and partial excess molar volumes V-bar i E have been also derived from the experimental data. The calculated values have been used to explain the dependency of intermolecular interaction between the mixing components on the alkyl substitution on benzene ring

Efeito do cromo nas propriedades catalíticas da MCM-41

OpenAIRE

Oliveira,Alcineia Conceição; Rangel,Maria do Carmo; Fierro,José Luís Garcia; Reyes,Patrício; Oportus,Marcelo

2005-01-01

The effect of chromium on the catalytic properties of MCM-41 was evaluated in order to develop new catalysts for the trimethylbenzene transalkylation with benzene to produce ethylbenzene, a high-value aromatic in the industry. It was found that chromium decreases the specific surface area but increases the acidity, turning MCM-41 into an active and selective catalyst for ethylbenzene and toluene production. The coke produced on the catalyst is hydrogenated and mainly located outside the pores...

Adsorption isotherms of some alkyl aromatic hydrocarbons and surface energies on partially dealuminated Y faujasite zeolite by inverse gas chromatography.

Science.gov (United States)

Kondor, Anett; Dallos, András

2014-10-03

Adsorption isotherm data of some alkyl aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) measured in the temperature range of 423-523K on a partially dealuminated faujasite type DAY F20 zeolite by inverse gas chromatography are presented in this work. The temperature dependent form of Tóth's equation has been fitted to the multiple temperature adsorption isotherms of benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene with standard deviations of 4.6, 5.0, 5.9, 4.3, 5.1 and 6.3mmolkg(-1) and coefficients of determinations (r(2)) of 0.977, 0.971, 0.974, 0.975, 0.991 and 0.991, respectively. The gas-solid equilibria and modeling were interpreted on the basis of the interfacial properties of the zeolite, by dispersive, specific and total surface energy heterogeneity profiles and distributions of the adsorbent measured by surface energy analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Petroleum hydrocarbon biodegradation under mixed denitrifying/microaerophilic conditions

International Nuclear Information System (INIS)

Miller, D.E.; Hutchins, S.R.

1995-01-01

Data are presented for aqueous-flow, soil-column microcosms in which removal of benzene, toluene, ethylbenzene, and xylenes (BTEX) is observed for two operating conditions: (1) nitrate, 25 to 26 mg(N)/L, as the single electron acceptor and (2) nitrate, 27 to 28 mg(N)/L combined with low levels of oxygen, 0.8 to 1.2 mg O 2 /L. Soils used in this study include aquifer material from Traverse City, Michigan; Park City, Kansas; and Eglin Air Force Base (AFB), Florida. BTEX compounds are introduced at concentrations ranging from 2.5 to 5 mg/L, with total BTEX loading from 20 to 22 mg/L Complete removal of toluene and partial removal of ethylbenzene, m-xylene, and o-xylene were observed for all soils during trials in which nitrate was the only electron acceptor. Combining low levels of oxygen with nitrate produced varying effects on BTEX removal, nitrate utilization, and nitrite production. Benzene proved recalcitrant throughout all operating trials

Evaluation of processing factors for selected organic contaminants during virgin olive oil production: Distribution of BTEXS during olives processing.

Science.gov (United States)

López-Blanco, Rafael; Gilbert-López, Bienvenida; Rojas-Jiménez, Rubén; Robles-Molina, José; Ramos-Martos, Natividad; García-Reyes, Juan F; Molina-Díaz, Antonio

2016-05-15

The presence of BTEXS (benzene, toluene, ethylbenzene, xylenes and styrene) in virgin olive oils can be attributed to environmental contamination, but also to biological processes during oil lipogenesis (styrene). In this work, the processing factor of BTEXS from olives to olive oil during its production was evaluated at lab-scale with an Abencor system. Benzene showed the lowest processing factor (15%), whereas toluene and xylenes showed an intermediate behavior (with 40-60% efficiency), and ethylbenzene and styrene were completely transferred (100%). In addition, an attempt to examine the contribution of potential sources to olives contamination with BTEXS was carried out for the first time. Two types of olives samples were classified according to their proximity to the contamination source (road). Although higher levels of BTEXS were found in samples close to roads, the concentrations were relatively low and do not constitute a major contribution to BTEXS usually detected in olive oil. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling the competitive effect of ammonium oxidizers and heterotrophs on the degradation of MTBE in a packed bed reactor

DEFF Research Database (Denmark)

Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

2008-01-01

A mathematical model was used to study effects on the degradation of methyl tert-butyl ether (MTBE) in a packed bed reactor due to the presence of contaminants such as ammonium, and the mix of benzene, toluene, ethylbenzene and xylenes (BTEX). It was shown that competition between the slower...

Practical Cost-Optimization of Characterization and Remediation Decisions at DNAPL Sites with Consideration of Prediction Uncertainty

Science.gov (United States)

2011-05-01

transverse dispersivity [m] BTEX benzene, toluene, ethylbenzene, and xylene B lumped parameter defined as /cal calB J M β= CDM Camp Dresser ...Groundwater at Fort Lewis generally flows to northwest in the Vashon aquifer and west- southwest in the SLA aquifer. A simplified geologic cross section of the

Effects of gasoline components on MTBE and TBA cometabolism by Mycobacterium austroafricanum JOB5.

Science.gov (United States)

House, Alan J; Hyman, Michael R

2010-07-01

In this study we have examined the effects of individual gasoline hydrocarbons (C(5-10,12,14) n-alkanes, C(5-8) isoalkanes, alicyclics [cyclopentane and methylcyclopentane] and BTEX compounds [benzene, toluene, ethylbenzene, m-, o-, and p-xylene]) on cometabolism of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA) by Mycobacterium austroafricanum JOB5. All of the alkanes tested supported growth and both MTBE and TBA oxidation. Growth on C(5-8) n-alkanes and isoalkanes was inhibited by acetylene whereas growth on longer chain n-alkanes was largely unaffected by this gas. However, oxidation of both MTBE and TBA by resting cells was consistently inhibited by acetylene, irrespective of the alkane used as growth-supporting substrate. A model involving two separate but co-expressed alkane-oxidizing enzyme systems is proposed to account for these observations. Cyclopentane, methylcyclopentane, benzene and ethylbenzene did not support growth but these compounds all inhibited MTBE and TBA oxidation by alkane-grown cells. In the case of benzene, the inhibition was shown to be due to competitive interactions with both MTBE and TBA. Several aromatic compounds (p-xylene > toluene > m-xylene) did support growth and cells previously grown on these substrates also oxidized MTBE and TBA. Low concentrations of toluene (TBA oxidation by alkane-grown cells whereas higher concentrations were inhibitory. The effects of acetylene suggest strain JOB5 also has two distinct toluene-oxidizing activities. These results have been discussed in terms of their impact on our understanding of MTBE and TBA cometabolism and the enzymes involved in these processes in mycobacteria and other bacteria.

Catalytic transformation of methyl benzenes over zeolite catalysts

KAUST Repository

Al-Khattaf, S.

2011-02-01

Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over ZSM-5, TNU-9, mordenite and SSZ-33 catalysts in a novel riser simulator at different operating conditions. Catalytic experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction conditions on the isomerization to disproportionation product ratio, distribution of trimethylbenzene (TMB) isomers, and p-xylene/o-xylene ratios are reported. The sequence of reactivity of the three alkyl benzenes depends upon the pore structure of zeolites. The zeolite structure controls primarily the diffusion of reactants and products while the acidity of these zeolites is of a secondary importance. In the case of medium pore zeolites, the order of conversion was m-xylene > 1,2,4-TMB > toluene. Over large pore zeolites the order of reactivity was 1,2,4-TMB > m-xylene > toluene for SSZ-33 catalyst, and m-xylene ∼ 1,2,4-TMB > toluene over mordenite. Significant effect of pore size between ZSM-5 and TNU-9 was observed; although TNU-9 is also 3D 10-ring channel system, its slightly larger pores compared with ZSM-5 provide sufficient reaction space to behave like large-pore zeolites in transformation of aromatic hydrocarbons. We have also carried out kinetic studies for these reactions and activation energies for all three reactants over all zeolite catalysts under study have been calculated. © 2011 Elsevier B.V.

Novel synthesis of methoxymethyl benzene by electrochemical coupling reaction of toluene with methanol in ionic liquid media.

Science.gov (United States)

Chen, Fengtao; Wang, Bo; Ma, Hongzhu

2009-06-15

An ionic liquid (1-butyl-3-methylimidazolium dibutyl phosphate) was prepared and characterized by cyclic voltammogram (CV) and Fourier transform infrared spectrometer (FT-IR). The ionic liquid exhibited good catalytic activity for the electrochemical reaction of toluene with methanol assisted with a pair of porous graphite plane electrodes and product yield higher than 56% was observed. In addition, the electrochemical process was detected by UV-vis spectrum and the products were analyzed by gas chromatography/mass spectrometry (GC/MS). According to the experimental results, a possible free radical reaction mechanism was proposed. It may be concluded that a simply and feasible electrochemical coupling reaction at room temperature and atmospheric pressure may be possible. Compared with methyl tert-butyl ether (MTBE), the main product (methoxymethyl benzene) used as booster to improve fuel combustion was also studied.

Atmospheric BTEX-concentrations in an area with intensive street traffic

Science.gov (United States)

Buczynska, Anna Jolanta; Krata, Agnieszka; Stranger, Marianne; Locateli Godoi, Ana Flavia; Kontozova-Deutsch, Velichka; Bencs, László; Naveau, Inge; Roekens, Edward; Van Grieken, René

The major threat to clean air in developed and industrializing countries is now posed by traffic emissions. The effects of traffic road modifications on the air quality are, however, rarely reported in the literature. The aim of this study was to determine the influence of the modernization and renovation of a traffic artery in the region of Mortsel (Antwerp, Belgium) on the concentration of volatile organic compounds such as: benzene, toluene, ethylbenzene and m-, p-, o-xylenes (BTEX). The original goal of the reconstruction works was to reduce the traffic lanes of one of the busiest streets in Antwerp, in order to discourage the road traffic and in consequence also to improve the air quality in this region. The average concentrations of BTEX before these works in 2003 were: 1.6, 7.0, 0.9, 2.3, and 0.9 μg/m 3, for benzene, toluene, ethylbenzene, m + p xylenes, and o-xylene, respectively. However, after the completion of the works, in 2005, they were slightly higher: 2.5, 9.5, 1.6, 3.4, and 1.3 μg/m 3, respectively. The scatter plots of benzene against toluene, ethylbenzene and xylenes in 2003 and 2005 showed very good correlations. This fact indicated that all of the measured compounds originated from the same source, namely the road traffic. Moreover, the data obtained from an air-monitoring station at less than 6 km distance from the sampling site (operated by the Flemish Environment Agency, and located in Borgerhout, Antwerp), confirmed the lack of influence of background concentrations of BTEX. The obtained results led to the conclusion that the reduction of the number of traffic lanes had apparently increased the traffic jams and also increased the emission from cars. Therefore, these modernization works had even a negative impact on the local concentration of traffic-related pollutants as BTEX.

Poluição e a densidade de vegetação: BTEX em algumas áreas públicas de Curitiba - PR, Brasil Pollution and density of vegetation: BTEX in some public areas of Curitiba - PR, Brazil

Directory of Open Access Journals (Sweden)

Ana Flavia Locateli Godoi

2010-01-01

Full Text Available The occurrence of benzene, toluene, ethylbenzene, and xylenes (BTEX in some public areas of Curitiba-PR, Brazil, was evaluated. Their concentrations were then related to the vegetation's density in each area. Average benzene concentrations varied from 3.9 to 6.1 μg m-3, with higher values occurring in poorly dense vegetation areas. For toluene, average concentrations ranged from 6.5 to 7.2 μg m-3. The effect of such pollutants was evaluated by means of a bio indicator, Tillandsia stricta. Variation in total chlorophyll content and in stomatic density were detected in some samples and may be related to the BTEX concentrations found in the studied areas.

Atmospheric levels of aldehydes and BTEX and their relationship with vehicular fleet changes in Rio de Janeiro urban area.

Science.gov (United States)

Martins, Eduardo Monteiro; Arbilla, Graciela; Bauerfeldt, Glauco Favilla; de Paula, Murilo

2007-05-01

A comprehensive monitoring campaign to assess aldehydes and BTEX concentrations was performed during 12 months, in the Tijuca district (Rio de Janeiro), an area with commercial activities and a high flux of vehicles. The mean concentrations of formaldehyde and acetaldehyde were 151 and 30 ppb, respectively. The high formaldehyde/acetaldehyde ratio was attributed to extensive use of compressed natural gas (CNG). The number of CNG vehicles in the metropolitan Region of Rio de Janeiro increased from 23000 in January 2001 to 161000 in January 2005. Monitoring data show that, for the same period, methane and formaldehyde concentrations increased while NO(x) and CO levels diminished. Mean concentrations for benzene, toluene, ethylbenzene, m,p-xylene and o-xylene, were 1.1, 4.8, 3.6, 10.4 and 3.0 micro gm(-3), respectively. Benzene and toluene concentrations were lower than the values determined in 1996, for the same location. The levels of ethylbenzene and xylenes determined in this work are similar to values obtained in 1996. This fact may be explained as a consequence of changes in the gasoline composition.

Evaluation of biomass production in unleaded gasoline and BTEX-fed batch reactors.

Science.gov (United States)

Acuna-Askar, K; Englande, A J; Ramirez-Medrano, A; Coronado-Guardiola, J E; Chavez-Gomez, B

2003-01-01

BTEX removal under aerobic conditions by unleaded gasoline acclimated biomass and BTEX acclimated biomass, and the effect of surfactant on BTEX biodegradation were evaluated. The effect of BTEX concentration as the sole source of carbon for biomass acclimation and the effect of yeast extract on cell growth in unleaded gasoline-fed reactors were also evaluated. For the unleaded gasoline acclimated biomass, benzene was shown the most recalcitrant among all BTEX, followed by o-xylene and toluene with 16-23%, 35-41% and 57-69% biodegradation, respectively. Ethylbenzene was consistently the fastest BTEX chemical removed with 99% biodegradation for the four bioreactor acclimated biomasses tested. For the 1,200 ppm BTEX acclimated biomass, benzene showed the highest removal efficiency (99%) among the four biomass environmental conditions tested, along with 99% toluene and 99% ethylbenzene biodegradation. O-xylene showed 92-94% removal. In all bioassays tested Tergitol NP-10 was fully removed, and did not have a substantial effect on BTEX biodegradation at the end of a 10-day evaluation.

Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

Science.gov (United States)

Zhu, Hongying; Huang, Guangming

2015-03-31

In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages. Copyright © 2015 Elsevier B.V. All rights reserved.

Geochemical indicators of intrinsic bioremediation

International Nuclear Information System (INIS)

Borden, R.C.; Gomez, C.A.; Becker, M.T.

1995-01-01

A detailed field investigation has been completed at a gasoline-contaminated aquifer near Rocky Point, NC, to examine possible indicators of intrinsic bioremediation and identify factors that may significantly influence the rae and extent of bioremediation. The dissolved plume of benzene, toluene, ethylbenzene, and xylene (BTEX) in ground water is naturally degrading. Toluene and o-xylene are most rapidly degraded followed by m-, p-xylene, and benzene. Ethylbenzene appears to degrade very slowly under anaerobic conditions present in the center of the plume. The rate and extent of biodegradation appears to be strongly influenced by the type and quantity of electron acceptors present in the aquifer. At the upgradient edge of the plume, nitrate, ferric iron, and oxygen are used as terminal electron acceptors during hydrocarbon biodegradation. The equivalent of 40 to 50 mg/l of hydrocarbon is degraded based on the increase in dissolved CO 2 relative to background ground water. Immediately downgradient of the source area, sulfate and iron are the dominant electron acceptors. Toluene and o-xylene are rapidly removed in this region. Once the available oxygen, nitrate, and sulfate are consumed, biodegradation is limited and appears to be controlled by mixing and aerobic biodegradation at the plume fringes

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Science.gov (United States)

Robertson, W J; Franzmann, P D; Mee, B J

2000-02-01

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Comparison of aromatic hydrocarbon measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

Directory of Open Access Journals (Sweden)

B. T. Jobson

2010-02-01

Full Text Available A comparison of aromatic hydrocarbon measurements is reported for the CENICA supersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003. Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS, long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS, and Gas Chromatography-Flame Ionization analysis (GC-FID of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6, and were in reasonable agreement for toluene, C₂-alkylbenzenes and C₃-alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430 m distance, and the point measurements collected at 37-m sampling height were best for benzene (r=0.61, and reasonably good for toluene, C₂-alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5. There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the PTR-MS ethylbenzene interference. Mixing ratios measured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C₂-alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients – horizontal, vertical, or both – in toluene mixing ratios were significant, and

Comparison of Aromatic Hydrocarbon Measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

International Nuclear Information System (INIS)

Jobson, Bertram T.; Volkamer, Rainer M.; Velasco, E.; Allwine, Gene; Westberg, Halvor H.; Lamb, Brian K.; Alexander, M.L.; Berkowitz, Carl M.; Molina, Luisa T.

2010-01-01

A comparison of aromatic hydrocarbon measurements is reported for the CENICA upersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003). Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS), long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS), and Gas Chromatography-Flame Ionization analysis (GC-FID) of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6), and were in reasonable agreement for toluene, C 2 -alkylbenzenes and C3-alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430m distance), and the point measurements collected at 37-m sampling height were best for benzene (r=0.61), and reasonably good for toluene, C2-alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5). There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the PTR-MS ethylbenzene interference. Mixing ratios easured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C2-alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients - horizontal, vertical, or both - in toluene mixing ratios were significant, and up to a factor of 2 despite the fact that all measurements were conducted above

Análise por cromatografia gasosa de BTEX nas emissões de motor de combustão interna alimentado com diesel e mistura diesel-biodiesel (B10 Analysis of BTEX in the emissions from an internal combustion engine burning diesel oil and diesel-biodiesel mixture (B10 by gas chromatography

Directory of Open Access Journals (Sweden)

Sérgio L. Ferreira

2008-01-01

Full Text Available This paper describes the procedures for analysing pollutant gases emitted by engines, such as volatile organic compounds (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene by using high resolution gas chromatography (HRGC. For IC engine burning, in a broad sense, the use of the B10 mixture reduces drastically the emissions of aromatic compounds. Especially for benzene the reduction of concentrations occurs at the level of about 24.5%. Although a concentration value below 1 µg mL-1 has been obtained, this reduction is extremely significant since benzene is a carcinogenic compound.

Fenton-like initiation of a toluene transformation mechanism

Science.gov (United States)

In Fenton-driven oxidation treatment systems, reaction intermediates derived from parent compounds can play a significant role in the overall treatment process. Fenton-like reactions in the presence of toluene or benzene, involved a transformation mechanism that was highly effici...

Anticonvulsant and antipunishment effects of toluene.

Science.gov (United States)

Wood, R W; Coleman, J B; Schuler, R; Cox, C

1984-08-01

Toluene can have striking acute behavioral effects and is subject to abuse by inhalation. To determine if its actions resemble those of drugs used in the treatment of anxiety ("anxiolytics"), two sets of experiments were undertaken. Inasmuch as prevention of pentylenetetrazol-induced convulsions is an identifying property of this class of agents, we first demonstrated that pretreatment with injections of toluene delayed the onset of convulsive signs and prevented the tonic extension phase of the convulsant activity in a dose-related manner. Injections of another alkyl benzene, m-xylene, were of comparable potency to toluene. Inhalation of toluene delayed the time to death after pentylenetetrazol injection in a manner related to the duration and concentration of exposure; at lower convulsant doses, inhalation of moderate concentrations (EC50, 1311 ppm) prevented death. Treatment with a benzodiazepine receptor antagonist (Ro 15-1788) failed to reduce the anticonvulsant activity of inhaled toluene. Anxiolytics also attenuate the reduction in response rate produced by punishment with electric shock. Toluene increased rates of responding suppressed by punishment when responding was maintained under a multiple fixed-interval fixed-interval punishment schedule of reinforcement. Distinct antipunishment effects were observed after 2 hr of exposure to 1780 and 3000 ppm of toluene; the rate-increasing effects of toluene were related to concentration and to time after the termination of exposure. Thus, toluene and m-xylene resemble in several respects clinically useful drugs such as the benzodiazepines.

Occupational health risk assessment of volatile organic compounds emitted from the coke production unit of a steel plant.

Science.gov (United States)

Dehghani, Fateme; Omidi, Fariborz; Heravizadeh, Omidreza; Barati Chamgordani, Saied; Gharibi, Vahid; Sotoudeh Manesh, Akbar

2018-03-27

In this study, cancer and non-cancer risks of exposure to volatile organic compounds in the coke production unit of a steel plant were evaluated. To determine individual exposure to benzene, toluene, xylene and ethylbenzene, personal samples were taken from the breathing zone of workers according to National Institute for Occupational Safety and Health (NIOSH) method 1501. Cancer and non-cancer risk assessment was performed, using US Environmental Protection Agency (US EPA) methods. Samples analysis showed that the concentration of benzene in the energy and biochemistry and the benzol refinement sections was higher than occupational exposure limits. The cancer risk for benzene in all sections was significantly higher than allowable limit; the non-cancer risk for benzene in all sections and toluene in the benzol refinement section was also higher than 1.0. In conclusion, the current control measures are not sufficient and should be improved for efficient control of occupational exposures.

Airborne concentrations of benzene associated with the historical use of some formulations of liquid wrench.

Science.gov (United States)

Williams, Pamela R D; Knutsen, Jeffrey S; Atkinson, Chris; Madl, Amy K; Paustenbach, Dennis J

2007-08-01

The current study characterizes potential inhalation exposures to benzene associated with the historical use of some formulations of Liquid Wrench under specific test conditions. This product is a multiuse penetrant and lubricant commonly used in a variety of consumer and industrial settings. The study entailed the remanufacturing of several product formulations to have similar physical and chemical properties to most nonaerosol Liquid Wrench formulations between 1960 and 1978. The airborne concentrations of benzene and other constituents during the simulated application of these products were measured under a range of conditions. Nearly 200 breathing zone and area bystander air samples were collected during 11 different product use scenarios. Depending on the tests performed, average airborne concentrations of benzene ranged from approximately 0.2-9.9 mg/m(3) (0.08-3.8 ppm) for the 15-min personal samples; 0.1-8 mg/m(3) (0.04-3 ppm) for the 1-hr personal samples; and 0.1-5.1 mg/m(3) (0.04-2 ppm) for the 1-hr area samples. The 1-hr personal samples encompassed two 15-min product applications and two 15-min periods of standing within 5 to 10 feet of the work area. The measured airborne concentrations of benzene varied significantly based on the benzene content of the formulation tested (1%, 3%, 14%, or 30% v/v benzene) and the indoor air exchange rate but did not vary much with the base formulation of the product or the two quantities of Liquid Wrench used. The airborne concentrations of five other volatile chemicals (ethylbenzene, toluene, total xylenes, cyclohexane, and hexane) were also measured, and the results were consistent with the volatility and concentrations of these chemicals in the product tested. A linear regression analysis of air concentration compared with the chemical mole fraction in the solution and air exchange rate provided a relatively good fit to the data. The results of this study should be useful for evaluating potential inhalation

Use of urinary biomarkers to characterize occupational exposure to BTEX in healthcare waste autoclave operators.

Science.gov (United States)

Rafiee, Ata; Delgado-Saborit, Juana Maria; Gordi, Elham; Quémerais, Bernadette; Kazemi Moghadam, Vahid; Lu, Wenjing; Hashemi, Fallah; Hoseini, Mohammad

2018-08-01

Urinary benzene, toluene, ethylbenzene, and xylenes (BTEX) can be used as a reliable biomarker of exposure to these pollutants. This study was aimed to investigate the urinary BTEX concentration in operators of healthcare waste (HCW) autoclaves. This cross-sectional study was conducted in selected hospitals in Tehran, Iran between April and June 2017. Twenty operators (as the case group) and twenty control subjects were enrolled in the study. Personal urine samples were collected at the beginning and end of the work shift. Urinary BTEX were measured by a headspace gas chromatography-mass spectrometry (GC/MS). A detailed questionnaire was used to gather information from subjects. Results showed that the median of urinary benzene, toluene, ethylbenzene, m-p xylene, and o-xylene levels in the exposed group were 3.26, 3.36, 0.84, 3.94 and 4.48 μg/L, respectively. With the exception of ethylbenzene, subjects in the exposed group had significantly higher urinary BTEX levels than control group (p autoclave used were also identified as predictors of urinary BTEX concentrations. The healthcare waste treatment autoclaves can be considered as a significant BTEX exposure source for operators working with these treatment facilities. The appropriate personal protection equipment and control measures capable in reducing BTEX exposure should be provided to HCW workers to reduce their exposures to BTEX. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation; Avaliacao da contaminacao da agua do mar por benzeno, tolueno e xileno na regiao de Ubatuba, litoral norte (SP) e estudo da degradacao destes compostos por radiacao ionizante

Energy Technology Data Exchange (ETDEWEB)

Almeida, Kelly Cristina Santana de

2006-07-01

A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 {mu}g/L for benzene, 0.70 {mu}g/L for toluene, and 1.54 {mu}g/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 {mu}g/L to 2.0 {mu}g/L, the concentration of toluene varied from < 0.70 {mu}g/L to 3.24 {mu}g/L and the maximum value of xylene observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard and exposed to ionizing radiation using a source of {sup 60}Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation; Avaliacao da contaminacao da agua do mar por benzeno, tolueno e xileno na regiao de Ubatuba, litoral norte (SP) e estudo da degradacao destes compostos por radiacao ionizante

Energy Technology Data Exchange (ETDEWEB)

Almeida, Kelly Cristina Santana de

2006-07-01

A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 {mu}g/L for benzene, 0.70 {mu}g/L for toluene, and 1.54 {mu}g/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 {mu}g/L to 2.0 {mu}g/L, the concentration of toluene varied from < 0.70 {mu}g/L to 3.24 {mu}g/L and the maximum value of xylene observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard and exposed to ionizing radiation using a source of {sup 60}Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

OpenAIRE

Pérez-Sánchez, Amaury; Sánchez, Eddy Javier Pérez; Segura Silva, Rutdali María

2017-01-01

Abstract Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried ou...

Information draft on the development of air standards for toluene

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-01-01

Toluene is a colorless, volatile liquid with a benzene-like odour. Its predominant use is in the production of benzene, as an octane enhancer in gasoline, as a solvent in aerosol spray paints, wall paints, lacquers, inks, adhesives, resins, and in such consumer products as spot removers, paint strippers, cosmetics, perfumes and antifreezes. Approximately 150 Ontario industrial sources reported toluene releases to the air totaling 4,245 to 5,300 tonnes during the reporting years from 1993 to 1996, making toluene one of the top pollutants by release quantities in Ontario and Canada for all these years. It is absorbed via the lungs and the gastrointestinal tract, both in humans and animals. Once absorbed, it tends to accumulate in the fatty tissues, and in vascularized tissues such as nerve cells and brain tissue. Toluene adversely affects the central nervous system (CNS) of humans and experimental animals. Observed symptoms in exposed humans range from decrease in psychometric performance, to headache, intoxication, convulsions, narcosis and death. Health Canada concluded that toluene is unlikely to be carcinogenic, although the available data is insufficient for definite classification. Ontario has 24-hour ambient air quality criterion and a half-hour Point of Impingement standard for toluene of 2,000 microgram/cubic meter, based on odour effects. The US Environmental Protection Agency inhalation reference concentration (also adopted by most of the American states) is 400 microgram/cubic meter. The WHO recommended a guideline value of 7500 microgram/cubic meter. Health Canada And Environment Canada established a tolerable concentration of 3750 microgram/cubic meter. 69 refs., 2 tabs., appendix

Simple and accurate quantification of BTEX in ambient air by SPME and GC-MS.

Science.gov (United States)

Baimatova, Nassiba; Kenessov, Bulat; Koziel, Jacek A; Carlsen, Lars; Bektassov, Marat; Demyanenko, Olga P

2016-07-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) comprise one of the most ubiquitous and hazardous groups of ambient air pollutants of concern. Application of standard analytical methods for quantification of BTEX is limited by the complexity of sampling and sample preparation equipment, and budget requirements. Methods based on SPME represent simpler alternative, but still require complex calibration procedures. The objective of this research was to develop a simpler, low-budget, and accurate method for quantification of BTEX in ambient air based on SPME and GC-MS. Standard 20-mL headspace vials were used for field air sampling and calibration. To avoid challenges with obtaining and working with 'zero' air, slope factors of external standard calibration were determined using standard addition and inherently polluted lab air. For polydimethylsiloxane (PDMS) fiber, differences between the slope factors of calibration plots obtained using lab and outdoor air were below 14%. PDMS fiber provided higher precision during calibration while the use of Carboxen/PDMS fiber resulted in lower detection limits for benzene and toluene. To provide sufficient accuracy, the use of 20mL vials requires triplicate sampling and analysis. The method was successfully applied for analysis of 108 ambient air samples from Almaty, Kazakhstan. Average concentrations of benzene, toluene, ethylbenzene and o-xylene were 53, 57, 11 and 14µgm(-3), respectively. The developed method can be modified for further quantification of a wider range of volatile organic compounds in air. In addition, the new method is amenable to automation. Copyright © 2016 Elsevier B.V. All rights reserved.

Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

OpenAIRE

Amaury Pérez Sánchez; Eddy Javier Pérez Sánchez; Rutdali María Segura Silva

2017-01-01

Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by usin...

Combined removal of a BTEX, TCE, and cis-DCE mixture using Pseudomonas sp. immobilized on scrap tyres.

Science.gov (United States)

Lu, Qihong; de Toledo, Renata Alves; Xie, Fei; Li, Junhui; Shim, Hojae

2015-09-01

The simultaneous aerobic removal of a mixture of benzene, toluene, ethylbenzene, and o,m,p-xylene (BTEX); cis-dichloroethylene (cis-DCE); and trichloroethylene (TCE) from the artificially contaminated water using an indigenous bacterial isolate identified as Pseudomonas plecoglossicida immobilized on waste scrap tyres was investigated. Suspended and immobilized conditions were compared for the removal of these volatile organic compounds. For the immobilized system, toluene, benzene, and ethylbenzene were completely removed, while the highest removal efficiencies of 99.0 ± 0.1, 96.8 ± 0.3, 73.6 ± 2.5, and 61.6 ± 0.9% were obtained for o-xylene, m,p-xylene, TCE, and cis-DCE, respectively. The sorption kinetics of contaminants towards tyre surface was also evaluated, and the sorption capacity generally followed the order of toluene > benzene > m,p-xylene > o-xylene > ethylbenzene > TCE > cis-DCE. Scrap tyres showed a good capability for the simultaneous sorption and bioremoval of BTEX/cis-DCE/TCE mixture, implying a promising waste material for the removal of contaminant mixture from industrial wastewater or contaminated groundwater.

Assessment of the BTEX concentrations and reactivity in a confined parking area in Rio de Janeiro, Brazil

Science.gov (United States)

de Castro, Barbara Prestes; de Souza Machado, Gladson; Bauerfeldt, Glauco Favila; Nunes Fortes, Julio Domingos; Martins, Eduardo Monteiro

2015-03-01

In this work, the contribution of evaporative emissions from light passenger vehicles to the degradation of the air quality was investigated on the basis of the indoor quantification of the monoaromatic volatile compounds Benzene, Toluene, Ethylbenzene and Xylenes (BTEX), specifically, a confined shopping mall parking area in the northern zone of Rio de Janeiro, a site that represents the reality of the vehicular fleet of the Metropolitan Region of Rio de Janeiro. In order to evaluate the concentration of the BTEX compounds, samples were collected, by an active sampling system using charcoal cartridge as adsorbent. The samples were extracted with organic solvent and subsequently analyzed by gas chromatography-mass spectrometry (GCMS). The average results were 54.14 μg m-3 (benzene), 209.24 μg m-3 (toluene), 45.87 μg m-3 (ethylbenzene) and 118.93 μg m-3 (xylenes). These results are compared with results from the literature of vehicular emissions in confined spaces such as garages and tunnels. Possible correlations with emissions from moving vehicles, obtained from previous studies in a tunnel of large circulation and emissions obtained in other underground parkings, are also investigated. The results suggest different emission sources.

Intrinsic bioremediation of a BTEX and MTBE plume under mixed aerobic/denitrifying conditions

International Nuclear Information System (INIS)

Borden, R.C.; Daniel, R.A.

1995-01-01

A shallow Coastal Plain aquifer in rural Sampson Country, North Carolina, has been contaminated with petroleum hydrocarbon from a leaking underground storage tank containing gasoline.An extensive field characterization has been performed to define the horizontal and vertical distribution of soluble gasoline components and indicator parameters. A plume of dissolved methyl tert-butyl ether (MTBE) and the aromatic hydrocarbons benzene, toluene, ethylbenzene, and xylene isomers (BTEX) is present in the aquifer and has migrated over 600 ft from the source area. Background dissolved oxygen concentrations range from 7 to 8 mg/L, and nitrate concentrations range from 5 to 22 mg/L as N due to extensive fertilization of fields surrounding the spill. In the center of the BTEX plume, oxygen concentrations decline to less than 1 mg/L while nitrate concentrations remain high. The total mass flux of MTBE and all BTEX components decline with distance downgradient relative to a conservative tracer (chloride). At the source, the total BTEX concentration exceeds 75 mg/L while 130 ft downgradient, total BTEX concentrations are less than 4.9 mg/L, a 15-fold reduction. Toluene and ethylbenzene decline most rapidly followed by m-p-xylene, o-xylene and finally benzene. Biodegradation of TEX appears to be enhanced by the excess nitrate present in the aquifer while benzene biodegradation appears to be due to strictly aerobic processes

Experimental and theoretical study of surface tension of binary mixtures of (n-alkyl acetates + heptane, benzene, and toluene)

International Nuclear Information System (INIS)

Rafati, Amir Abbas; Ghasemian, Ensieh

2009-01-01

Surface properties of binary mixtures of (n-alkyl acetates + heptane, benzene, and toluene) have been measured by surface tension method at T = 298.15 K and atmospheric pressure. Also, the surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures with a group contribution method for the calculation of activity coefficient. The mean relative standard deviations obtained from the comparison of experimental (measured) and calculated surface tension values for the eight binary systems are less than 1.5%, which leads to concluding that the model shows a good accuracy in different situations in comparison with other predicted equations. In addition, the relative Gibbs adsorption and the surface mole fraction have been evaluated using this model. The surface tension deviations were calculated from experimental results and have been fitted to the Redlich-Kister type polynomial relation

Epoxidation of cyclohexene by ethyl-benzene hydroperoxide in the presence of molybdenum catalyst

International Nuclear Information System (INIS)

Sapunov, V.N.; Litvintsev, I.Yu.; Margitfal'vi, J.; Lebedev, N.N.

1977-01-01

A study has been made of the kinetic experimental pattern and mechanism of epoxidation of cyclohexene by ethylbenzene hydroperoxide during catalysis by Mo(CO) 6 in various solvents. A first order of reaction with respect to the catalyst and complex order of reaction with respect to the hydroperoxide and olefine have been established. Simple (square and cross) inhibition by reaction products, cyclohexene oxide and methylphenylcarbinol, have been found. An increase in the dielectric constant of the solvent diminishes the epoxidation rate. The mechanism scheme of the process is proposed and main kinetic parameters calculated

Highly selective GaN-nanowire/TiO2-nanocluster hybrid sensors for detection of benzene and related environment pollutants

International Nuclear Information System (INIS)

Aluri, Geetha S; Motayed, Abhishek; Davydov, Albert V; Oleshko, Vladimir P; Bertness, Kris A; Sanford, Norman A; Rao, Mulpuri V

2011-01-01

Nanowire-nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires (NWs) with titanium dioxide (TiO 2 ) nanoclusters for selectively sensing benzene and other related aromatic compounds. Hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN NWs followed by the deposition of TiO 2 nanoclusters using RF magnetron sputtering. The sensor fabrication process employed standard microfabrication techniques. X-ray diffraction and high-resolution analytical transmission electron microscopy using energy-dispersive x-ray and electron energy-loss spectroscopies confirmed the presence of the anatase phase in TiO 2 clusters after post-deposition anneal at 700 deg. C. A change of current was observed for these hybrid sensors when exposed to the vapors of aromatic compounds (benzene, toluene, ethylbenzene, xylene and chlorobenzene mixed with air) under UV excitation, while they had no response to non-aromatic organic compounds such as methanol, ethanol, isopropanol, chloroform, acetone and 1,3-hexadiene. The sensitivity range for the noted aromatic compounds except chlorobenzene were from 1% down to 50 parts per billion (ppb) at room temperature. By combining the enhanced catalytic properties of the TiO 2 nanoclusters with the sensitive transduction capability of the nanowires, an ultra-sensitive and selective chemical sensing architecture is demonstrated. We have proposed a mechanism that could qualitatively explain the observed sensing behavior.

Two-step treatment of harmful industrial wastewater: an analysis of microbial reactor with integrated membrane retention for benzene and toluene removal

Directory of Open Access Journals (Sweden)

Trusek-Holownia Anna

2015-12-01

Full Text Available Standards for highly toxic and carcinogenic pollutants impose strict guidelines, requiring values close to zero, regarding the degradation of such pollutants in industrial streams. In many cases, classic bioremoval processes fail. Therefore, we proposed a stream leaving the microbial membrane bioreactor (MBR that is directed to an additional membrane separation mode (NF/RO. Under certain conditions, the integrated process not only benefits the environment but may also increase the profitability of the bioreactor operation. An appropriate model was developed and tested in which the bioremoval of benzene and toluene by Pseudomonas fluorescens was used as an example. This paper presents equations for selecting the operation parameters of the integrated system to achieve the expected degree of industrial wastewater purification.

Demonstration of In situ Anaerobic Transformation of Toluene and Xylene Using Single-Well Push-Pull Tests and Deuterated BTEX Surrogates

Science.gov (United States)

Field, J. A.; Reusser, D. E.; Beller, H. R.; Istok, J. D.

2001-12-01

Obtaining unambiguous evidence of in-situ transformation of benzene, toluene, ethylbenzene and xylene (BTEX) in the subsurface is a difficult task. Recently, benzylsuccinic acid and its methyl analogues were shown to be unequivocal degradation products of anaerobic toluene and xylene biodegradation. Conducting tracer tests at BTEX-contaminated field sites is problematic because background contaminant concentrations potentially interfere with the interpretation of field test data. To avoid the time and cost associated with removing background contaminants, alternative approaches are needed. Deuterated analogs of toluene and xylene are well-suited for use in field tracer tests because they are inexpensive and can be distinguished analytically from background toluene and xylene. In this study, single-well push-pull tests, in which deuterated toluene and xylene were injected, were performed to assess the in-situ anaerobic biotransformation of toluene and xylene in BTEX-contaminated wells. A total of 4 single-well push-pull tests were conducted at BTEX-contaminated field sites near Portland, OR and Kansas City, KS. Test solutions consisting of 100 mg/L bromide, 250 mg/L nitrate, 0.4 to 2.5 mg/L toluene-d8, and 0.4 to 1.0 mg/L o-xylene-d10.were injected at a rate of 0.5 - 2 L/min. During the extraction phase, samples were taken daily to biweekly for up to 30 days. Samples for volatile organic analytes were collected in 40-mL volatile organic analysis (VOA) vials without headspace. Samples for BSA and methyl-BSA were collected in 1 L glass bottles and preserved with 5% (w/w) formalin. Samples were shipped on ice and stored at 4 C until analysis. Unambiguous evidence of toluene and xylene biotransformation was obtained with the in-situ formation of BSA and methyl-BSA. The concentrations of BSA ranged from below the detection limit (0.2 ug/L) to 1.5 ug/L. The concentrations of methyl-BSA ranged from below detection to the quantitation limit (0.7 ug/L). The highest BSA

Degradative capacities and bioaugmentation potential of an anaerobic benzene-degrading bacterium strain DN11

Energy Technology Data Exchange (ETDEWEB)

Yuki Kasai; Yumiko Kodama; Yoh Takahata; Toshihiro Hoaki; Kazuya Watanabe [Marine Biotechnology Institute, Kamaishi (Japan)

2007-09-15

Azoarcus sp. strain DN11 is a denitrifying bacterium capable of benzene degradation under anaerobic conditions. The present study evaluated strain DN11 for its application to bioaugmentation of benzene-contaminated underground aquifers. Strain DN11 could grow on benzene, toluene, m-xylene, and benzoate as the sole carbon and energy sources under nitrate-reducing conditions, although o- and p-xylenes were transformed in the presence of toluene. Phenol was not utilized under anaerobic conditions. Kinetic analysis of anaerobic benzene degradation estimated its apparent affinity and inhibition constants to be 0.82 and 11 {mu}M, respectively. Benzene-contaminated groundwater taken from a former coal-distillation plant site in Aichi, Japan was anaerobically incubated in laboratory bottles and supplemented with either inorganic nutrients (nitrogen, phosphorus, and nitrate) alone, or the nutrients plus strain DN11, showing that benzene was significantly degraded only when DN11 was introduced. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments, and quantitative PCR revealed that DN11 decreased after benzene was degraded. Following the decrease in DN11 16S rRNA gene fragments corresponding to bacteria related to Owenweeksia hongkongensis and Pelotomaculum isophthalicum, appeared as strong bands, suggesting possible metabolic interactions in anaerobic benzene degradation. Results suggest that DN11 is potentially useful for degrading benzene that contaminates underground aquifers at relatively low concentrations. 50 refs., 6 figs., 1 tab.

The impact of candle burning during All Saints' Day ceremonies on ambient alkyl-substituted benzene concentrations.

Science.gov (United States)

Olszowski, Tomasz; Kłos, Andrzej

2013-11-01

Research findings concerning benzene, toluene, ethylobenzene, meta-, para- and ortho-xylene as well as styrene (BTEXS) emission at public cemeteries during All Saints' Day are presented here. Tests were carried out at town-located cemeteries in Opole and Grodków (southern Poland) and, as a benchmark, at the centres of those same towns. The purpose of the study was to estimate BTEXS emissions caused by the candle burning and, equally important to examine, whether emissions generated by the tested sources were similar to the BTEXS emissions generated by road transport. During the festive period, significant increases in benzene concentrations, by 200 % and 144 %, were noted at the cemeteries in Opole and Grodków, as well as in toluene, by 366 % and 342 %, respectively. Styrene concentrations also increased. It was demonstrated that the ratio of toluene to benzene concentrations from emissions caused by the burning candles are comparable to the ratio established for transportation emissions.

Parallel characterization of anaerobic toluene- and ethylbenzene-degrading microbial consortia by PCR-denaturing gradient gel electrophoresis, RNA-DNA membrane hybridization, and DNA microarray technology

Science.gov (United States)

Koizumi, Yoshikazu; Kelly, John J.; Nakagawa, Tatsunori; Urakawa, Hidetoshi; El-Fantroussi, Said; Al-Muzaini, Saleh; Fukui, Manabu; Urushigawa, Yoshikuni; Stahl, David A.

2002-01-01

A mesophilic toluene-degrading consortium (TDC) and an ethylbenzene-degrading consortium (EDC) were established under sulfate-reducing conditions. These consortia were first characterized by denaturing gradient gel electrophoresis (DGGE) fingerprinting of PCR-amplified 16S rRNA gene fragments, followed by sequencing. The sequences of the major bands (T-1 and E-2) belonging to TDC and EDC, respectively, were affiliated with the family Desulfobacteriaceae. Another major band from EDC (E-1) was related to an uncultured non-sulfate-reducing soil bacterium. Oligonucleotide probes specific for the 16S rRNAs of target organisms corresponding to T-1, E-1, and E-2 were designed, and hybridization conditions were optimized for two analytical formats, membrane and DNA microarray hybridization. Both formats were used to characterize the TDC and EDC, and the results of both were consistent with DGGE analysis. In order to assess the utility of the microarray format for analysis of environmental samples, oil-contaminated sediments from the coast of Kuwait were analyzed. The DNA microarray successfully detected bacterial nucleic acids from these samples, but probes targeting specific groups of sulfate-reducing bacteria did not give positive signals. The results of this study demonstrate the limitations and the potential utility of DNA microarrays for microbial community analysis.

Polyfunctional catalyst for processiing benzene fractions

Energy Technology Data Exchange (ETDEWEB)

G. Byakov; B.D. Zubitskii; B.G. Tryasunov; I.Ya. Petrov [Kuznetsk Basin State Technical University, Kemerovo (Russian Federation)

2009-05-15

A by-product of the coke industry is a raw benzene fraction benzene- 1 which may serve as for catalytic processes. The paper reports a study on the influence of the composition and temperatures on the activity and selectivity of NiO-V{sub 2}O{sub 6}-MoO{sub 3}/{gamma}-Al{sub 2}O{sub 3} catalysts and the corresponding binary and tertiary subsystems are studied by a pulse method in model reactions; the hydrodealkylating of toluene and the hydrodesulfurizing of thioprhene. The optimal catalyst composition is established. The new catalyst is compared with industrial catalysts.

Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity

Directory of Open Access Journals (Sweden)

T. Karl

2009-01-01

Full Text Available Toluene and benzene are used for assessing the ability to measure disjunct eddy covariance (DEC fluxes of Volatile Organic Compounds (VOC using Proton Transfer Reaction Mass Spectrometry (PTR-MS on aircraft. Statistically significant correlation between vertical wind speed and mixing ratios suggests that airborne VOC eddy covariance (EC flux measurements using PTR-MS are feasible. City-median midday toluene and benzene fluxes are calculated to be on the order of 14.1±4.0 mg/m²/h and 4.7±2.3 mg/m²/h, respectively. For comparison the adjusted CAM2004 emission inventory estimates toluene fluxes of 10 mg/m²/h along the footprint of the flight-track. Wavelet analysis of instantaneous toluene and benzene measurements during city overpasses is tested as a tool to assess surface emission heterogeneity. High toluene to benzene flux ratios above an industrial district (e.g. 10–15 g/g including the International airport (e.g. 3–5 g/g and a mean flux (concentration ratio of 3.2±0.5 g/g (3.9±0.3 g/g across Mexico City indicate that evaporative fuel and industrial emissions play an important role for the prevalence of aromatic compounds. Based on a tracer model, which was constrained by BTEX (BTEX– Benzene/Toluene/Ethylbenzene/m, p, o-Xylenes compound concentration ratios, the fuel marker methyl-tertiary-butyl-ether (MTBE and the biomass burning marker acetonitrile (CH₃CN, we show that a combination of industrial, evaporative fuel, and exhaust emissions account for >87% of all BTEX sources. Our observations suggest that biomass burning emissions play a minor role for the abundance of BTEX compounds in the MCMA (2–13%.

Efeito do cromo nas propriedades catalíticas da MCM-41 The effect of chromium on the catalytic properties of MCM-41

Directory of Open Access Journals (Sweden)

Alcineia Conceição Oliveira

2005-02-01

Full Text Available The effect of chromium on the catalytic properties of MCM-41 was evaluated in order to develop new catalysts for the trimethylbenzene transalkylation with benzene to produce ethylbenzene, a high-value aromatic in the industry. It was found that chromium decreases the specific surface area but increases the acidity, turning MCM-41 into an active and selective catalyst for ethylbenzene and toluene production. The coke produced on the catalyst is hydrogenated and mainly located outside the pores and thus can be easily removed. The catalyst is more active and selective than mordenite, a commercial catalyst, and thus more promising for commercial applications.

Photochemical reaction of triplet 9,10-anthraquinone with ethylbenzene in the presence of DPPH as a radical trapping agent

International Nuclear Information System (INIS)

Moger, G.

1983-01-01

DPPH was used as a scavenger of α-phenyl-ethyl radicals produced in the photochemical reaction between triplet anthraquinone (Qsup(T)) and ethylbenzene (RH 2 ) in benzene solutions. The rate constant ratio ksub(2)/ksub(-1) was determined from the measurements of the quantum yield of scavenging against (RH 2 ) and found to be (0.49+-0.015) M at 25 deg C. (author)

Hydrocarbon removal with constructed wetlands

OpenAIRE

Eke, Paul Emeka

2008-01-01

Wetlands have long played a significant role as natural purification systems, and have been effectively used to treat domestic, agricultural and industrial wastewater. However, very little is known about the biochemical processes involved, and the use of constructed treatment wetlands in the removal of petroleum aromatic hydrocarbons from produced and/or processed water. Wastewaters from the oil industry contain aromatic hydrocarbons such as benzene, toluene, ethylbenzene and x...

Solubility, density and excess molar volume of binary mixtures of aromatic compounds and common ionic liquids at T=283.15K and atmospheric pressure

OpenAIRE

Emilio J Gonzalez; Patricia Requejo; Filipa Maia; Ángeles Dominguez; Maria Eugénia Macedo

2015-01-01

In this work, the solubility of aromatic compounds (benzene, or toluene, or ethylbenzene, or o-xylene, or m-xylene, or p-xylene) in several ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, or 1-propyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, or 1-ethyl-3-methylpyridinium ethylsulfate, or 1-hexyl-3-methylimidazolium dicyana...

Ordered mesoporous carbon film as an effective solid-phase microextraction coating for determination of benzene series from aqueous media

Energy Technology Data Exchange (ETDEWEB)

Jiang, Hui [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); School of Geography Science, Nantong University, Nantong 226001 (China); Li, Jiansheng, E-mail: lijsh@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Jiang, Mingyue; Lu, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Lianjun, E-mail: wanglj@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

2015-08-12

The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m{sup 2}/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5–500 μg/L), low detection limits (0.01–0.05 μg/L) and good repeatabilities (4.0–5.8% for one fiber, 2.9–8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs. - Highlights: • Ordered mesoporous carbon film supported on graphite fiber was first reported as solid-phase microextraction coating. • The strategy for the film preparation was combined dip-coating technology with evaporation-induced self-assembly approach. • The obtained fiber showed enhanced thermal stability and organic solvents resistance. • The

Substoichiometric isotope dilution analysis of arsenic in biological and environmental standard reference materials by solvent extraction using toluene-3,4-dithiol in benzene

International Nuclear Information System (INIS)

Chutke, N.L.; Ambulkar, Ms.M.N.; Weginwar, R.G.; Garg, A.N.

1994-01-01

A radiochemical solvent extraction procedure has been developed for the determination of As(III) using 76 As tracer. It is based on the complexation of As(III) with toluene-3,4-dithiol (TDT) at pH 2 and subsequent extraction in benzene. The effect of various parameters such as pH, time of equilibration, nature of solvent, quantitative character and interferences have been studied. The method has been further developed into substoichiometric isotope dilution analysis for the determination of As at < 1μg level and employed for the analysis of several environmental and biological standard Reference Materials from NIST (USA), IAEA (Vienna) and NIES (Japan). (author) 39 refs.; 4 figs.; 4 tabs

Chemical composition of surgical smoke formed in the abdominal cavity during laparoscopic cholecystectomy – Assessment of the risk to the patient

Directory of Open Access Journals (Sweden)

Miłosz Dobrogowski

2014-04-01

Full Text Available Objectives: The aim of this study was to assess the exposure of patients to organic substances produced and identified in surgical smoke formed in the abdominal cavity during laparoscopic cholecystectomy. Material and Methods: Identification of these substances in surgical smoke was performed by the use of gas chromatography-mass spectrometry (GC-MS with selective ion monitoring (SIM. The selected biomarkers of exposure to surgical smoke included benzene, toluene, ethylbenzene and xylene. Their concentrations in the urine samples collected from each patient before and after the surgery were determined by SPME-GC/MS. Results: Qualitative analysis of the smoke produced during laparoscopic procedures revealed the presence of a wide variety of potentially toxic chemicals such as benzene, toluene, xylene, dioxins and other substances. The average concentrations of benzene and toluene in the urine of the patients who underwent laparoscopic cholecystectomy, in contrast to the other determined compounds, were significantly higher after the surgery than before it, which indicates that they were absorbed. Conclusions: The source of the compounds produced in the abdominal cavity during the surgery is tissue pyrolysis in the presence of carbon dioxide atmosphere. All patients undergoing laparoscopic procedures are at risk of absorbing and excreting smoke by-products. Exposure of the patient to emerging chemical compounds is usually a one-time and short-term incident, yet concentrations of benzene and toluene found in the urine were significantly higher after the surgery than before it.

Site-specific variability in BTEX biodegradation under denitrifying conditions

International Nuclear Information System (INIS)

Kao, C.M.; Borden, R.C.

1997-01-01

Laboratory microcosm experiments were conducted to evaluate the feasibility of benzene, toluene, ethylbenzene, m-xylene, and o-xylene (BTEX) biodegradation under denitrifying conditions. Nine different sources of inocula, including contaminated and uncontaminated soil cores from four different sites and activated sludge, were used to establish microcosms. BTEX was not degraded under denitrifying conditions in microcosms inoculated with aquifer material from Rocky Point and Traverse City. However, rapid depletion of glucose under denitrifying conditions was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing aquifer material from Fort Bragg and Sleeping Bear Dunes and sewage sludge. Benzene was recalcitrant in all microcosms tested. The degradation of o-xylene ceased after toluene, ethylbenzene, and m-xylene were depleted in the Fort Bragg and sludge microcosms, but o-xylene continued to degrade in microcosms with contaminated Sleeping Bear Dunes soil. The most probable number (MPN) of denitrifiers in these nine different inocula were measured using a microtiter technique. There was no correlation between the MPN of denitrifiers and the TEX degradation rate under denitrifying conditions. Experimental results indicate that the degradation sequence and TEX degradation rate under denitrifying conditions may differ among sites. Results also indicate that denitrification alone may not be a suitable bioremediation technology for gasoline-contaminated aquifers because of the inability of denitrifiers to degrade benzene

Toluene degradation by non-thermal plasma combined with a ferroelectric catalyst.

Science.gov (United States)

Liang, Wen-Jun; Ma, Lin; Liu, Huan; Li, Jian

2013-08-01

Degradation of toluene in a gas by non-thermal plasma with a ferroelectric catalyst was studied at normal temperature and atmospheric pressure. Spontaneous polarization material (BaTiO3) and photocatalyst (TiO2) were added into plasma system simultively. Toluene degradation efficiency and specific energy density during the discharge process were investigated. Furthermore, byproducts and degradation mechanisms of toluene were also investigated. The toluene degradation efficiency increased when non-thermal plasma technology was combined with the catalyst. The toluene degradation efficiencies of the different catalysts tested were in the following order: BaTiO3/TiO2>BaTiO3>TiO2>no catalyst. A mass ratio of 2.38:1 was optimum for the BaTiO3 and TiO2 catalyst. The outlet gas was analyzed by gas chromatography and Fourier transform infrared spectroscopy, and the main compounds detected were CO2, H2O, O3 and benzene ring derivatives. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dielectric properties of liquid systems: study of interactions in the systems carbon tetrachloride with benzene, toluene, and p-xylene

Directory of Open Access Journals (Sweden)

Adrián H. Buep

2014-12-01

Full Text Available Intermolecular associations in liquid systems of non-polar and slightly polar compounds were studied through excess molar volumes (VEM and excess dielectric properties (εE and n2ED for mixtures of carbon tetrachloride (CCl4 with benzene (C6H6, toluene (C6H5CH3, and p-xylene (p-(CH32C6H4. These excess properties were calculated from measurements of density (ρ, static permittivity (ε, and refractive index (nD over the whole range of concentrations at 298.15 K. The values of the excess dielectric properties for these mixtures were fitted in two different ways, one through least squares using the Redlich–Kister equation and the other using a model developed to explain deviations from ideality. The first fit was found to be descriptive while the second gave the equilibrium constant values for the interaction products actually formed in the mixtures and the respective electronic polarizabilities and dipole moments, indicating the existence of interaction products.

BTEX compounds in water - future trends and directions for water treatment

OpenAIRE

Fayemiwo, OM; Daramola, MO; Moothi, K

2017-01-01

BTEX (benzene, toluene, ethylbenzene, and xylene) compounds are common water resource and potable water pollutants that are often left undetected and untreated by municipal treatment systems in spite of the negative repercussions associated with their ingestion. The US EPA has classified these pollutants as priority pollutant, yet they are persistently present in a variety of water resources. In this review paper, we highlight the sources and reported concentrations of BTEX compounds in water...

Surfactant use with nitrate-based bioremediation

International Nuclear Information System (INIS)

Wilson, B.H.; Hutchins, S.R.; West, C.C.

1995-01-01

This study presents results of an initial survey on the effect of six surfactants on the biodegradation of petroleum hydrocarbons in bioremediation applications using nitrate as the electron acceptor. Aquifer material from Park City, Kansas, was used for the study. The three atomic surfactants chosen were Steol CS-330, Dowfax 8390 and sodium dodecylbenzene sulfonate (SDBS); the three nonionic surfactants were T-MAZ-60, Triton X-100, and Igepal CO-660. Both Steol CS-330 and T-MAZ-60 biodegraded under denitrifying conditions. The Steol inhibited biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXTMB). Only toluene was rapidly degraded in the presence of T-MAZ-60. Biodegradation of all compounds, including toluene, appears to be inhibited by Dowfax 8390 and SDBS. No biodegradation of Dowfax 8390 or SDBS was observed. SDBS inhibited denitrification, but Dowfax 8390 did not. For the microcosms containing Triton X-100 or Igepal CO-660, removal of toluene, ethylbenzene, m-xylene, 1,3,5-TMB, and 1,2,4-TMB were similar to their removals in the no-surfactant treatment. These two surfactants did not biodegrade, did not inhibit biodegradation of the alkylbenzenes, and did not inhibit denitrification. Further studies are continuing with aquifer material from Eglin Air Force Base

Occupational Exposure of Petroleum Depot Workers to BTEX Compounds

Directory of Open Access Journals (Sweden)

M Rezazadeh Azari

2011-12-01

Full Text Available Background: Benzene, toluene, ethylbenzene and xylene (BTEX are the most important toxic volatile compounds in the air and could be easily absorbed through the respiratory tract. In recent years, the risk of exposure to BTEX compounds, especially benzene as a carcinogen, has been considered in petroleum depot stations. Objective: To assess the occupational exposure of petroleum depot workers in Iran to BTEX compounds. Methods: After completing a questionnaire and assessing occupational exposure to BTEX compounds, 78 (46 exposed and 32 non-exposed depot workers were randomly selected to participate in this study. Air sampling and analysis of BTEX was conducted according to the NIOSH method No. 1501. Analysis of urinary hippuric acid, as an indicator of toluene exposure, was carried out according to NIOSH method No. 8300. Personal monitoring of the high exposure group to BTEX compounds was repeated to verify the results obtained in the first phase of the monitoring. Results: Among the 9 operating groups studied, occupational exposure to benzene and toluene was higher in quality control and gasoline loading operators—the median exposure ranged from 0.16 to 1.63 ppm for benzene and 0.2 to 2.72 ppm for toluene. Median exposure of other group members to BTEX compounds was below the detection limit of analytical method (0.07, 0.06, 0.05, and 0.05 ppm, respectively. The level of toluene exposure measured showed correlation with neither post-shift urinary hippuric acid (Spearman's rho=0.128, p=0.982 nor with the difference between post- and pre-shift urinary hippuric acid (Spearman's rho=0.089, p=0.847 in depot operational workers. Conclusion: Gasoline loading operators are exposed to a relatively high level of benzene.

Socioeconomic and personal behavioral factors affecting children's exposure to VOCs in urban areas in Korea.

Science.gov (United States)

Byun, Hyaejeong; Ryu, Kyongnam; Jang, Kyungjo; Bae, Hyunjoo; Kim, Dongjin; Shin, Hosung; Chu, Jangmin; Yoon, Chungsik

2010-02-01

Volatile organic compounds (VOCs) are known to cause adverse health effects. We investigated the relationships between children's VOC exposure and socioeconomic and human activity factors with passive personal samplers, questionnaires, and time-activity diaries (TAD). Statistical analyses were conducted using SAS 9.1, and the results were organized using SigmaPlot 8.0 software. Chemicals such as benzene, toluene, 2-butanone, ethylbenzene, xylene, chloroform, n-hexane, heptane, and some kinds of decanes, which are known to adversely affect public health, were identified in measured samples. These were mainly emitted from outdoor sources (e.g., vehicular traffic) or indoor sources (e.g., household activities such as cooking and cleaning) or both. We concluded that region was the most important socioeconomic factor affecting children's VOC exposure, and the significant compounds were n-hexane (p = 0.006), 1,1,1-trichloroethane (p = 0.001), benzene (p = 0.003), toluene (p = 0.002), ethylbenzene (p = 0.020), m-, p-xylene (p = 0.014), dodecane (p = 0.003), and hexadecane (p = 0.001). Parental education, year of home construction and type of housing were also slightly correlated with personal VOC exposure. Only the concentration of o-xylene (p = 0.027) was significantly affected by the parental education, and the concentrations of benzene (p = 0.030) and 2-butanone (p = 0.049) by the type of housing. Also, tridecane (p = 0.049) and n-hexane (p = 0.033) were significantly associated with the year of home construction. When household activities such as cooking were performed indoors, children's VOC concentrations tended to be higher, especially for n-hexane, chloroform, heptane, toluene (p factors simultaneously, socioeconomic factors such as region had a greater effect on children's VOC exposures than indoor activities. From this study, we can suggest that socioeconomic factors as well as environmental factors should be considered when formulating environmental policy to

Dissolution rate of BTEX contaminants in water

International Nuclear Information System (INIS)

Njobuenwu, D.O.; Amadi, S.A.; Ukpaka, P.C.

2005-01-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) and substituted benzenes are the most common aromatic compounds in petroleum. BTEX components are the most soluble and mobile fraction of crude oil and many petroleum products, and frequently enter soil, sediments and aquatic environments because of accidental spills, leaks and improper oil waste disposal practices. The mass transfer process of hydrocarbons in aquatic mediums has received considerable attention in the literature. This paper focused on the molecular mass transfer rate of BTEX in water, with the aim of understanding and predicting contaminant fate and transport. A comprehensive model was developed to simulate the molecular dissolution rate of BTEX in a natural water stream. The model considered the physicochemical properties of the BTEX compounds and physical processes relevant to the spreading of contaminants in the sea. The dissolution rate was a function of oil slick area, dissolution mass transferability and oil solubility in water. The total dissolution rate N was calculated and the dissolution mass transfer coefficient K was given as the point value of mass transfer coefficient. Results for the dissolution rate based on the solubility of the components in the water were compared with analytical solutions from previous studies and showed good agreement. The model showed that benzene had the largest dissolution rate, while o-xylene had the lowest rate because of its lower fraction. Benzene dissolution rate was approximately 2.6, which was 20.6 times that of toluene and ethylbenzene. It was concluded that the model is useful in predicting and monitoring the dissolution rate of BTEX contaminants in soil and water systems. 22 refs., 2 tabs., 3 figs

Mutual diffusion of binary liquid mixtures containing methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride

Energy Technology Data Exchange (ETDEWEB)

Guevara-Carrion, Gabriela; Janzen, Tatjana; Muñoz-Muñoz, Y. Mauricio; Vrabec, Jadran, E-mail: jadran.vrabec@uni-paderborn.de [Thermodynamics and Energy Technology, University of Paderborn, 33098 Paderborn (Germany)

2016-03-28

Mutual diffusion coefficients of all 20 binary liquid mixtures that can be formed out of methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride without a miscibility gap are studied at ambient conditions of temperature and pressure in the entire composition range. The considered mixtures show a varying mixing behavior from almost ideal to strongly non-ideal. Predictive molecular dynamics simulations employing the Green-Kubo formalism are carried out. Radial distribution functions are analyzed to gain an understanding of the liquid structure influencing the diffusion processes. It is shown that cluster formation in mixtures containing one alcoholic component has a significant impact on the diffusion process. The estimation of the thermodynamic factor from experimental vapor-liquid equilibrium data is investigated, considering three excess Gibbs energy models, i.e., Wilson, NRTL, and UNIQUAC. It is found that the Wilson model yields the thermodynamic factor that best suits the simulation results for the prediction of the Fick diffusion coefficient. Four semi-empirical methods for the prediction of the self-diffusion coefficients and nine predictive equations for the Fick diffusion coefficient are assessed and it is found that methods based on local composition models are more reliable. Finally, the shear viscosity and thermal conductivity are predicted and in most cases favorably compared with experimental literature values.

Are biogenic emissions a significant source of summertime atmospheric toluene in the rural Northeastern United States?

OpenAIRE

M. L. White; R. S. Russo; Y. Zhou; J. L. Ambrose; K. Haase; E. K. Frinak; R. K. Varner; O. W. Wingenter; H. Mao; R. Talbot; B. C. Sive

2009-01-01

Summertime atmospheric toluene enhancements at Thompson Farm in the rural northeastern United States were unexpected and resulted in a toluene/benzene seasonal pattern that was distinctly different from that of other anthropogenic volatile organic compounds. Consequently, three hydrocarbon sources were investigated for potential contributions to the enhancements during 2004–2006. These included: (1) increased warm season fuel evaporation coupled with changes in reformulated gasoline (RFG) con...

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents.

Science.gov (United States)

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng; Ma, Jing

2018-03-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o -cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o -cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o -cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260-280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o -cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o -cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively.

Mass concentrations of BTEX inside air environment of buses in Changsha, China

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiaokai; Zhang, Guoqiang; Zhang, Quan [College of Civil Engineering, Hunan University, Changsha 410082, Hunan (China); Chen, Hong [College of Environmental Science and Engineering, Hunan University, Changsha 410082, Hunan (China)

2011-02-15

In order to estimate the mass concentrations of benzene (B), toluene (T), ethylbenzene (E) and xylenes (X) inside air environment of buses and to analyze the influencing factors of the BTEX pollution levels, 22 public buses were investigated in Changsha, China. The interior air was collected through activated charcoal adsorption tubes and then the air samples were analyzed with thermally desorbed gas chromatograph. The mass concentrations ranged from 21.3 to 106.4 {mu}g/m{sup 3} for benzene, from 53.5 to 266.0 {mu}g/m{sup 3} for toluene, from 19.6 to 95.9 {mu}g/m{sup 3} for ethylbenzene and from 46.9 to 234.8 {mu}g/m{sup 3} for xylenes. Their mean values were 68.7, 179.7, 62.5 and 151.8 {mu}g/m{sup 3}, respectively. The rates of buses tested where the interior concentrations exceeded the limit levels of Chinese Indoor Air Quality Standard were 45.5% for toluene and 13.6% for xylenes. The BTEX levels increased when in-car temperature or relative humidity rose, and decreased when car age or travel distance increased. The BTEX concentrations were higher in leather trims buses than in non-leather trims ones, in air-conditioned buses than in non-air-conditioned ones, and in high-grade buses than in low-grade ones. According to the analysis of multiple linear regression equation, car age and in-car temperature were two most important factors influencing the BTEX pollution levels in the cabins of public buses. (author)

Benzene biodegradation using an anaerobic column coupled to Mn(IV) reduction

Energy Technology Data Exchange (ETDEWEB)

Villatoro-Monzon, W.R.; Velasquez-Mejia, E.K.; Morales-Ibarria, M.G.; Razo-Flores, E. [Instituto Mexicano del Petroleo (Mexico). Programo de Biotenologia del Petroleo

2004-07-01

Benzene, toluene, and o, m, p-xylene compounds make up a large proportion of gasoline. Due to spills and leaks from underground tanks, these compounds frequently contaminate groundwater and sediment. In particular the high solubility of benzene makes it very mobile and an extra danger to groundwater. Moreover, there are strong links between benzene and cancer and thus benzene is considered a serious pollutant. Contaminated sites usually become anaerobic due to microbe action. In this study, benzene biodegradation was done in a glass column inoculated with anaerobic Rhine River sediment and using Mn(IV) as the final electron acceptor. Under steady state operation, benzene biodegradation efficiency was as high as 95 per cent. Carbon dioxide and Mn(II) recovery rates were 81 and 77 per cent respectively. Reactor sediment was withdrawn on day 104 and subject to DGGE profiling. This sediment showed different band patterns than the original sediment that was not exposed to benzene. The authors conclude that the species associated with the degradation of benzene are of the genus Propionibacterium and Actinomyces. 17 refs., 2 figs.

Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab

2014-10-22

The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab; Raj, Abhijeet Dhayal; Alshoaibi, Ahmed S.; Alhassan, Saeed M.; Chung, Suk-Ho

2014-01-01

The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

Benzene observations and source appointment in a region of oil and natural gas development

Science.gov (United States)

Halliday, Hannah Selene

Benzene is a primarily anthropogenic volatile organic compound (VOC) with a small number of well characterized sources. Atmospheric benzene affects human health and welfare, and low level exposure (Atmospheric Observatory (PAO) in Colorado to investigate how O&NG development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's DISCOVER-AQ field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO. A limited information source attribution with the PAO dataset was completed using the EPA's positive matrix factorization (PMF) source receptor model. Six VOCs from the PTR-QMS measurement were used along with CO and NO for a total of eight chemical species. Six sources

Indole-based assay to assess the effect of ethanol on Pseudomonas putida F1 dioxygenase activity.

Science.gov (United States)

da Silva, Márcio Luis Busi; Alvarez, Pedro J J

2010-06-01

Toluene dioxygenase (TDO) is ubiquitous in nature and has a broad substrate range, including benzene, toluene, ethylbenzene and xylenes (BTEX). Pseudomonas putida F1 (PpF1) induced on toluene is known to produce indigo from indole through the activity of TDO. In this work, a spectrophotometric assay previously developed to measure indole to indigo production rates was modified to characterize the effects of various ethanol concentrations on toluene aerobic biodegradation activity and assess catabolite repression of TDO. Indigo production rate by cells induced on toluene alone was 0.0012 +/- 0.0006 OD(610) min(-1). The presence of ethanol did not fully repress TDO activity when toluene was also available as a carbon source. However, indigo production rates by PpF1 grown on ethanol:toluene mixtures (3:1 w/w) decreased by approximately 50%. Overall, the proposed spectrophotometric assay is a simple approach to quantify TDO activity, and demonstrates how the presence of ethanol in groundwater contaminated with reformulated gasoline is likely to interfere with naturally occurring microorganisms from fully expressing their aerobic catabolic potential towards hydrocarbons bioremediation.

Turbulence effects on volatilization rates of liquids and solutes.

Science.gov (United States)

Lee, Jiunn-Fwu; Chao, Huan-Ping; Chiou, Cary T; Manes, Milton

2004-08-15

Volatilization rates of neat liquids (benzene, toluene, fluorobenzene, bromobenzene, ethylbenzene, m-xylene, o-xylene, o-dichlorobenzene, and 1-methylnaphthalene) and of solutes (phenol, m-cresol, benzene, toluene, ethylbenzene, o-xylene, and ethylene dibromide) from dilute water solutions have been measured in the laboratory over a wide range of air speeds and water-stirring rates. The overall transfer coefficients (K(L)) for individual solutes are independent of whether they are in single- or multi-solute solutions. The gas-film transfer coefficients (kG) for solutes in the two-film model, which have hitherto been estimated by extrapolation from reference coefficients, can now be determined directly from the volatilization rates of neat liquids through a new algorithm. The associated liquid-film transfer coefficients (kL) can then be obtained from measured K(L) and kG values and solute Henry law constants (H). This approach provides a novel means for checking the precision of any kL and kG estimation methods for ultimate prediction of K(L). The improved kG estimation enables accurate K(L) predictions for low-volatility (i.e., low-H) solutes where K(L) and kGH are essentially equal. In addition, the prediction of K(L) values for high-volatility (i.e., high-H) solutes, where K(L) approximately equal to kL, is also improved by using appropriate reference kL values.

Field demonstration of natural biodegradation of BTEX compounds

International Nuclear Information System (INIS)

Borden, R.C.; Davis, C.W.; LeBrun, L.E. IV

1993-01-01

An extensive field study is being conducted at an underground storage tank (UST) release in Sampson Co., NC to aid in understanding the physical, chemical and biological processes controlling the rate and extent of natural bioremediation. Uncontaminated groundwater at the site contains roughly 5 mg/l dissolved oxygen and 15 mg/l nitrate as N. Although the USTs and some soil were removed, much of the NAPL contaminated soil could not be excavated and remains behind as a continuing source of dissolved BTEX. The NAPL gasoline in the subsurface has been naturally biodegrading for several years. Because of the low ground water velocity and high levels of contamination, bioremediation is not yet complete but the effects of oxygen and nitrates enhanced bioremediation are evident. Toluene, ethylbenzene, m + p-xylene and to a lesser extent o-xylene are rapidly removed in a zone less than 125 ft (40 m) wide immediately downgradient from the NAPL source area. A long narrow plume of dissolved benzene and MTBE persists and is migrating downgradient towards a small creek. Biodegradation of the benzene plume appears to be limited by diffusion of oxygen into the anoxic plume. In aerobic microcosms, all BTEX components were rapidly removed to below detection. Toluene and ethylbenzene were removed to below 10 ug/l in the denitrifying microcosms after an extended lag period

Turbulence effects on volatilization rates of liquids and solutes

Science.gov (United States)

Lee, J.-F.; Chao, H.-P.; Chiou, C.T.; Manes, M.

2004-01-01

Volatilization rates of neat liquids (benzene, toluene, fluorobenzene, bromobenzene, ethylbenzene, m-xylene, o-xylene, o-dichlorobenzene, and 1-methylnaphthalene) and of solutes (phenol, m-cresol, benzene, toluene, ethylbenzene, o-xylene, and ethylene dibromide) from dilute water solutions have been measured in the laboratory over a wide range of air speeds and water-stirring rates. The overall transfer coefficients (KL) for individual solutes are independent of whether they are in single- or multi-solute solutions. The gas-film transfer coefficients (kG) for solutes in the two-film model, which have hitherto been estimated by extrapolation from reference coefficients, can now be determined directly from the volatilization rates of neatliquids through anew algorithm. The associated liquid-film transfer coefficients (KL) can then be obtained from measured KL and kG values and solute Henry law constants (H). This approach provides a novel means for checking the precision of any kL and kG estimation methods for ultimate prediction of KL. The improved kG estimation enables accurate K L predictions for low-volatility (i.e., low-H) solutes where K L and kGH are essentially equal. In addition, the prediction of KL values for high-volatility (i.e., high-H) solutes, where KL ??? kL, is also improved by using appropriate reference kL values.

Reductions in commuter exposure to volatile organic compounds in Mexico City due to the environmental program ProAire2002-2010.

Science.gov (United States)

Shinohara, Naohide; Ángeles, Felipe; Basaldud, Roberto; Cardenas, Beatriz; Wakamatsu, Shinji

2017-05-01

We investigated commuter exposure to volatile organic compounds in the metropolitan area of Mexico City in 2011 in private car, microbus, bus, metro, metrobus, and trolley bus. A similar survey was conducted in 2002 before initiation of the ProAire2002-2010 program aimed at reducing air pollution. Formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene were sampled while traveling during the morning rush hour in May 2011. Compared with the 2002 survey, in-vehicle concentrations were substantially lower in 2011, except for formaldehyde in microbuses (35% higher than in 2002). The reductions were 17-42% (except microbuses), 25-44%, 41-61%, 43-61%, 71-79%, 80-91%, and 79-93% for formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene, respectively. These reductions are considered to be the outcome of some of the actions in the ProAire2002-2010 program. In some microbuses, use of liquid petroleum gas may have increased in-vehicle formaldehyde concentrations. The reduction in predicted excess cancer incidence of commuters because of ProAire2002-2010 was estimated to be 1.4 cases/yr. In addition, if every microbus commuter changed their transport mode to bus, metro, or metrobus in the future, the estimated excess cancer incidence of commuters could be further decreased from 6.4 to 0.88-2.2 cases/year.

Thermodynamic properties of (tetradecane + benzene, + toluene, + chlorobenzene, + bromobenzene, + anisole) binary mixtures at T = (298.15, 303.15, and 308.15) K

International Nuclear Information System (INIS)

Mutalik, Venkatesh; Manjeshwar, Lata S.; Sairam, Malladi; Aminabhavi, Tejraj M.

2006-01-01

Density ρ, viscosity η, and refractive index n D , values for (tetradecane + benzene, + toluene, + chlorobenzene, + bromobenzene, + anisole) binary mixtures over the entire range of mole fraction have been measured at temperatures (298.15, 303.15, and 308.15) K at atmospheric pressure. The speed of sound u has been measured at T = 298.15 K only. Using these data, excess molar volume V E , deviations in viscosity Δη, Lorentz-Lorenz molar refraction ΔR, speed of sound Δu, and isentropic compressibility Δk s have been calculated. These results have been fitted to the Redlich and Kister polynomial equation to estimate the binary interaction parameters and standard deviations. Excess molar volumes have exhibited both positive and negative trends in many mixtures, depending upon the nature of the second component of the mixture. For the (tetradecane + chlorobenzene) binary mixture, an incipient inversion has been observed. Calculated thermodynamic quantities have been discussed in terms of intermolecular interactions between mixing components

Selective Oxidation of Cyclohexene, Toluene and Ethyl Benzene Catalyzed by Bis-(L-tyrosinatocopper(II, Immersed in a Magnetite-Infused Silica Matrix

Directory of Open Access Journals (Sweden)

Massomeh Ghorbanloo

2016-01-01

Full Text Available Bis-(L-tyrosinatocopper(II was reacted with 3-(chloropropyl-trimethoxysilane functionalized silica that has infused magnetite to yield a magnetically separable catalyst in which the copper carboxylate is covalently linked to the silica matrix through the silane linkage. The immobilized catalyst has been characterized by spectroscopic studies (such as FT-IR, EPR, Magnetic Measurement, SEM and chemical analyses. The immobilized catalytic system functions as an efficient heterogeneous catalyst for oxidation of cyclohexene, toluene and ethyl benzene in the presence of hydrogen peroxide (as an oxidant and sodium bicarbonate (a co-catalyst. The reaction conditions have been optimized for solvent, temperature and amount of oxidant and catalyst. Comparison of the encapsulated catalyst with the corresponding homogeneous catalyst showed that the heterogeneous catalyst had higher activity and selectivity than the homogeneous catalyst. The immobilized catalyst could be readily recovered from the reaction mixture by using a simple magnet, and  reused up to five times without any loss of activity.

Adsorption of benzene and toluene from aqueous solutions onto activated carbon and its acid and heat treated forms: influence of surface chemistry on adsorption.

Science.gov (United States)

Wibowo, N; Setyadhi, L; Wibowo, D; Setiawan, J; Ismadji, S

2007-07-19

The influence of surface chemistry and solution pH on the adsorption of benzene and toluene on activated carbon and its acid and heat treated forms were studied. A commercial coal-based activated carbon F-400 was chosen as carbon parent. The carbon samples were obtained by modification of F-400 by means of chemical treatment with HNO3 and thermal treatment under nitrogen flow. The treatment with nitric acid caused the introduction of a significant number of oxygenated acidic surface groups onto the carbon surface, while the heat treatment increases the basicity of carbon. The pore characteristics were not significantly changed after these modifications. The dispersive interactions are the most important factor in this adsorption process. Activated carbon with low oxygenated acidic surface groups (F-400Tox) has the best adsorption capacity.

Experimental densities, refractive indices, and speeds of sound of 12 binary mixtures containing alkanes and aromatic compounds at T = 313.15 K

International Nuclear Information System (INIS)

Calvar, Noelia; Gomez, Elena; Gonzalez, Begona; Dominguez, Angeles

2009-01-01

Densities, speeds of sound, and refractive indices of 12 binary systems of alkanes (hexane, heptane, octane, and nonane) with aromatics (benzene, or toluene, or ethylbenzene) at T = 313.15 K and at atmospheric pressure were determined over the whole composition range, and are presented in this paper. From the experimental results, the derived and excess properties (isentropic compressibility, excess molar volumes, and excess molar isentropic compressibility) at T = 313.15 K were calculated and satisfactorily fitted to the Redlich-Kister equation.

Radiolysis of Aqueous Toluene Solutions

International Nuclear Information System (INIS)

Christensen, H.C.; Gustafson, R.

1971-04-01

Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N 2 O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N 2 O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H 2 ). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

Air Pollutant Mapping with a Mobile Laboratory during the BEE-TEX Field Study

Directory of Open Access Journals (Sweden)

Tara I. Yacovitch

2015-01-01

Full Text Available The Aerodyne Mobile Laboratory was deployed to the Houston Ship Channel and surrounding areas during the Benzene and Other Toxics Exposure field study in February 2015. We evaluated atmospheric concentrations of volatile organic hydrocarbons and other hazardous air pollutants of importance to human health, including benzene, 1,3-butadiene, toluene, xylenes, ethylbenzenes, styrene, and NO 2 . Ambient concentration measurements were focused on the neighborhoods of Manchester, Harrisburg, and Galena Park. The most likely measured concentration of 1,3-butadiene in the Manchester neighborhood (0.17 ppb exceeds the Environmental Protection Agency's E-5 lifetime cancer risk level of 0.14 ppb. In all the three neighborhoods, the measured benzene concentration falls below or within the E-5 lifetime cancer risk levels of 0.4–1.4 ppb for benzene. Pollution maps as a function of wind direction show the impact of nearby sources.

Which hydrogen atom of toluene protonates PAH molecules in (+)-mode APPI MS analysis?

Science.gov (United States)

Ahmed, Arif; Ghosh, Manik Kumer; Choi, Myung Chul; Choi, Cheol Ho; Kim, Sunghwan

2013-03-01

A previous study (Ahmed, A. et al., Anal. Chem. 84, 1146-1151( 2012) reported that toluene used as a solvent was the proton source for polyaromatic hydrocarbon compounds (PAHs) that were subjected to (+)-mode atmospheric-pressure photoionization. In the current study, the exact position of the hydrogen atom in the toluene molecule (either a methyl hydrogen or an aromatic ring hydrogen) involved in the formation of protonated PAH ions was investigated. Experimental analyses of benzene and anisole demonstrated that although the aromatic hydrogen atom of toluene did not contribute to the formation of protonated anthracene, it did contribute to the formation of protonated acridine. Thermochemical data and quantum mechanical calculations showed that the protonation of anthracene by an aromatic ring hydrogen atom of toluene is endothermic, while protonation by a methyl hydrogen atom is exothermic. However, protonation of acridine by either an aromatic ring hydrogen or a methyl hydrogen atom of toluene is exothermic. The different behavior of acridine and anthracene was attributed to differences in gas-phase basicity. It was concluded that both types of hydrogen in toluene can be used for protonation of PAH compounds, but a methyl hydrogen atom is preferred, especially for non-basic compounds.

Occupational Exposure of Diesel Station Workers to BTEX Compounds at a Bus Depot

Directory of Open Access Journals (Sweden)

Raeesa Moolla

2015-04-01

Full Text Available Diesel fuel is known to emit pollutants that have a negative impact on environmental and human health. In developing countries like South Africa, attendants are employed to pump fuel for customers at service stations. Attendants refuel vehicles with various octane unleaded fuel, lead-replacement petrol and diesel fuel, on a daily basis. Attendants are at risk to adverse health effects associated with the inhalation of volatile organic compounds released from these fuels. The pollutants released include benzene, toluene, ethylbenzene and xylenes (BTEX, which are significant due to their high level of toxicity. In this study, a risk assessment of BTEX was conducted at a diesel service station for public buses. Using Radiello passive samplers, it was found that benzene concentrations were above recommended international standards. Due to poor ventilation and high exposure duration, the average benzene concentration over the sampling campaign exceeded the US Environmental Protection Agency’s chronic inhalation exposure reference concentration. Lifetime cancer risk estimation showed that on average there is a 3.78 × 10−4 cancer risk, corresponding to an average chronic daily intake of 1.38 × 10−3 mg/kg/day of benzene exposure. Additionally, there were incidences where individuals were at potential hazard risk of benzene and toluene that may pose non-carcinogenic effects to employees.

Evaporative Gasoline Emissions and Asthma Symptoms

Science.gov (United States)

Gordian, Mary Ellen; Stewart, Alistair W; Morris, Stephen S

2010-01-01

Attached garages are known to be associated with indoor air volatile organic compounds (VOCs). This study looked at indoor exposure to VOCs presumably from evaporative emissions of gasoline. Alaskan gasoline contains 5% benzene making benzene a marker for gasoline exposure. A survey of randomly chosen houses with attached garages was done in Anchorage Alaska to determine the exposure and assess respiratory health. Householders were asked to complete a health survey for each person and a household survey. They monitored indoor air in their primary living space for benzene, toluene, ethylbenzene and xylenes for one week using passive organic vapor monitoring badges. Benzene levels in homes ranged from undetectable to 58 parts per billion. The median benzene level in 509 homes tested was 2.96 ppb. Elevated benzene levels in the home were strongly associated with small engines and gasoline stored in the garage. High concentrations of benzene in gasoline increase indoor air levels of benzene in residences with attached garages exposing people to benzene at levels above ATSDR’s minimal risk level. Residents reported more severe symptoms of asthma in the homes with high gasoline exposure (16%) where benzene levels exceeded the 9 ppb. PMID:20948946

Temperature influence on mixing properties of {ethyl tert-butyl ether (ETBE) + gasoline additives}

International Nuclear Information System (INIS)

Gonzalez-Olmos, R.; Iglesias, M.

2007-01-01

The densities and ultrasonic velocity of {ethyl tert-butyl ether (ETBE) + (benzene, toluene, ethylbenzene, isooctane, tert-butyl alcohol, and ethanol)} over the temperature range (288.15 to 323.15) K and atmospheric pressure, have been measured over the whole concentration range. The experimental excess volumes and deviation of isentropic compressibilities data have been analysed in terms of different theoretical models. The gathered data improve open literature related to gasoline additives, and help to understand the ETBE volumetric and acoustic trend into different chemical environment

2-{1-[2-(Bis{2-[1-(5-chloro-2-hydroxyphenylethylideneamino]ethyl}aminoethyliminio]ethyl}-4-chlorophenolate toluene hemisolvate

Directory of Open Access Journals (Sweden)

Seik Weng Ng

2009-02-01

Full Text Available In the toluene hemisolvated tripodal tris(2-aminoethylamine Schiff base, C30H33Cl3N4O3·0.5C7H8, one of the three imino N atoms is protonated, forming a hydrogen bond with the O atom at an adjacent benzene ring. The other two imino N atoms act as hydrogen-bond acceptors from phenolate OH groups. The toluene solvent molecule is disordered about a centre of inversion.

Dermal exposure assessment to benzene and toluene using charcoal cloth pads

NARCIS (Netherlands)

Wendel de Joode, B. van; Tielemans, E.; Vermeulen, R.; Wegh, H.; Kromhout, H.

2005-01-01

Charcoal cloth pads have been used to assess volatile chemicals on the skin in a laboratory setting; however, they have not yet been applied to measure dermal exposure in occupational settings. This study aimed at evaluating whether charcoal pads can be used to assess dermal exposure to benzene and

Correlation and prediction of the phase behavior and thermal properties of binary and ternary systems of 2,2′-oxybis[propane] + benzene, toluene, cyclohexane or n-heptane

International Nuclear Information System (INIS)

Didaoui, Saéda; Ait-Kaci, Ahmed

2013-01-01

Highlights: ► To provide original data of excess enthalpies of systems containing additive gasoline. ► To predict excess functions using statistical model. ► To examine the thermal behavior of ethers with hydrocarbons using theoretical models. ► Increasing information of thermodynamic behavior will increase quality of the fuel and economy. - Abstract: The experimental excess molar enthalpies data of liquid binary and ternary mixtures of DIPE with benzene, toluene, cyclohexane and n-heptane have been measured at 303.15 K and constant pressure using a Calvet type microcalorimeter, C80 (Setaram, France). A Redlich–Kister type equation was used to correlate experimental values. The theoretical results obtained by the DISQUAC model are significantly closer to the experimental values

Correlation and prediction of the phase behavior and thermal properties of binary and ternary systems of 2,2′-oxybis[propane] + benzene, toluene, cyclohexane or n-heptane

Energy Technology Data Exchange (ETDEWEB)

Didaoui, Saéda, E-mail: sdidaoui@hotmail.com [Laboratoire de thermodynamique et de modélisation moléculaire, Faculté de chimie, Université des Sciences et de la Technologie Houari Boumediene B.P.32, El-Alia Bab-Ezzouar 16111 Alger (Algeria); Ait-Kaci, Ahmed [Laboratoire de thermodynamique et de modélisation moléculaire, Faculté de chimie, Université des Sciences et de la Technologie Houari Boumediene B.P.32, El-Alia Bab-Ezzouar 16111 Alger (Algeria)

2013-09-10

Highlights: ► To provide original data of excess enthalpies of systems containing additive gasoline. ► To predict excess functions using statistical model. ► To examine the thermal behavior of ethers with hydrocarbons using theoretical models. ► Increasing information of thermodynamic behavior will increase quality of the fuel and economy. - Abstract: The experimental excess molar enthalpies data of liquid binary and ternary mixtures of DIPE with benzene, toluene, cyclohexane and n-heptane have been measured at 303.15 K and constant pressure using a Calvet type microcalorimeter, C80 (Setaram, France). A Redlich–Kister type equation was used to correlate experimental values. The theoretical results obtained by the DISQUAC model are significantly closer to the experimental values.

Outline and operations of benzene plant

Energy Technology Data Exchange (ETDEWEB)

Omori, S; Hirooka, N; Nakamura, M; Goto, T

1983-01-01

An account is given of plant which can process 130,000 tonnes of by-product coke oven gas light oil (GLO) per year (via hydrodesulfurization, extraction and distillation) to produce benzene, toluene and xylene. The flowsheets and component equipment of the various production processes are explained, together with special features such as the production of hydrogen from coke oven gas by the PSA process and the processing of GLO by the ARCO process. Plant operation is outlined and the results of performance tests are noted.

Organic chemistry. A rhodium catalyst for single-step styrene production from benzene and ethylene.

Science.gov (United States)

Vaughan, Benjamin A; Webster-Gardiner, Michael S; Cundari, Thomas R; Gunnoe, T Brent

2015-04-24

Rising global demand for fossil resources has prompted a renewed interest in catalyst technologies that increase the efficiency of conversion of hydrocarbons from petroleum and natural gas to higher-value materials. Styrene is currently produced from benzene and ethylene through the intermediacy of ethylbenzene, which must be dehydrogenated in a separate step. The direct oxidative conversion of benzene and ethylene to styrene could provide a more efficient route, but achieving high selectivity and yield for this reaction has been challenging. Here, we report that the Rh catalyst ((Fl)DAB)Rh(TFA)(η(2)-C2H4) [(Fl)DAB is N,N'-bis(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; TFA is trifluoroacetate] converts benzene, ethylene, and Cu(II) acetate to styrene, Cu(I) acetate, and acetic acid with 100% selectivity and yields ≥95%. Turnover numbers >800 have been demonstrated, with catalyst stability up to 96 hours. Copyright © 2015, American Association for the Advancement of Science.

Radiolysis of Aqueous Toluene Solutions

Energy Technology Data Exchange (ETDEWEB)

Christensen, H C; Gustafson, R

1971-04-15

Aqueous toluene solutions have been irradiated with Co gamma-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N{sub 2}O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G = 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N{sub 2}O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H{sub 2}). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

Background Atmospheric Levels of Aldehydes, BTEX and PM10 Pollutants in a Medium-Sized City of Southern Italy

International Nuclear Information System (INIS)

Iovino, P.; Salvestrini, S.; Capasso, S.

2007-01-01

Background atmospheric levels of aldehydes, BTEX and PM10 pollutants were measured in the suburb of Caserta (Italy), 75 thousands inhabitants, 41 0 04' N, on rainless weekdays and weekends during 2005. On weekdays the average daily concentrations (μg m -3 ) were 41.6 PM10, 8.6 benzene, 25.2 toluene, 6.3 ethylbenzene, 14.0 (m+p)-xylene, 11.7 o-xylene, 6.5 formaldehyde, 3.3 acetaldehyde. All the pollutant concentrations were strictly correlated (mean correlation coefficients = 0.90). At weekends the concentrations were lower by about 1.6 times. Both on weekdays and at weekends the PM10 and benzene levels exceeded the limits set by the EU Directive 30/1999 and 69/2000, respectively

Densities and excess volumes of binary mixtures of N,N-dimethylformamide with aromatic hydrocarbon at different temperature

International Nuclear Information System (INIS)

Peng Sanjun; Hou Haiyun; Zhou Congshan; Yang Tao

2007-01-01

Density of three binary mixtures formed by N,N-dimethylformamide (DMF) with aromatic hydrocarbon (one of benzene, toluene, and ethylbenzene) has been determined over the full range of compositions at the temperatures range (293.15 to 353.15)K and atmospheric pressure using a vibrating-tube densimeter. From these experiments, excess molar volumes (V m E ) could be calculated and fitted by the fourth-order Redlich-Kister equation, so the coefficients and the standard error (σ) could be got. Our result shows V m E decreases when temperature increases in the studied systems

Effect of temperature on the physical properties of two ionic liquids

International Nuclear Information System (INIS)

Pereiro, Ana B.; Veiga, Helena I.M.; Esperanca, Jose M.S.S.; Rodriguez, Ana

2009-01-01

Density, speed of sound, refractive index, and dynamic viscosity of the ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, BMpyr NTf 2 , and trihexyl(tetradecyl) phosphonium dicyanamide, P 66614 dca, were studied as a function of temperature at atmospheric pressure. Thermal expansion coefficient, α p , molecular volumes, and standard entropies of these ILs were calculated from the experimental density values. The solubility of three aromatic components (benzene, toluene, and ethylbenzene) in the selected ILs was carried out at T = 298.15 K and atmospheric pressure and compared with literature values for sulfolane.

Degradation of BTEX in aqueous solution by hydrodynamic cavitation

Energy Technology Data Exchange (ETDEWEB)

Braeutigam, P.; Wu, Z.-L.; Stark, A.; Ondruschka, B. [Institute for Technical Chemistry and Environmental Chemistry, Friedrich Schiller University, Jena (Germany)

2009-05-15

A self-made low-pressure device (up to 100 psi) for hydrodynamic cavitation was tested with the reaction of BTEX (benzene, toluene, ethylbenzene, and xylenes) in water. Experimental parameters, such as inlet pressure, solution temperature, and concentration of the chosen substrates, as well as the effect of different restrictions were investigated. The energy efficiency of the process was measured in comparison to two acoustic cavitation systems (24 and 850 kHz). The products of the BTEX degradation were identified and a pyrolytic degradation pathway is concluded. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Dealkylation of alkylbenzenes: a significant pathway in the toluene, o-, m-, p-xylene + OH reaction.

Science.gov (United States)

Noda, Jun; Volkamer, Rainer; Molina, Mario J

2009-09-03

The OH-radical initiated oxidation of a series of monocyclic aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylene) in the presence of oxygen and NO(x) was investigated in a flowtube coupled with a chemical ionization mass spectrometer (CIMS). OH-radical addition to the aromatic ring--the major reaction pathway--has previously been shown to have a particular sensitivity to experimental conditions. This is the first flowtube study that demonstrates the atmospheric relevance of product yields from the OH-addition channel on the millisecond time scale (35-75 ms); the phenol yield from benzene and cresol yields from toluene are found to be 51.0 +/- 4.3% and 17.7 +/- 2.1%, in excellent agreement with previous studies under close to atmospheric conditions. We further report unambiguous experimental evidence that dealkylation is a novel and significant pathway for toluene and o-, m-, and p-xylene oxidation. At 150 Torr of O2 partial pressure, toluene is found to dealkylate with a yield of 5.4 +/- 1.2% phenol; similarly, m-, o-, and p-xylene dealkylate with yields of 11.2 +/- 3.8%, 4.5 +/- 3.2%, and 4.3 +/- 3.1% cresol, respectively. A dealkylation mechanism via OH-addition in the ipso position is feasible (DeltaH = -9 kcal/mol for phenol formation from toluene) but does not lend itself easily to explain the significant isomer effect observed among xylenes; instead an alternative mechanism is presented that can explain this isomer effect and forms phenol and likely epoxide type products with identical m/z (indistinguishable in our CIMS analysis) via a carbene-type intermediate. Dealkylation adds to the atmospheric production of phenol- and likely epoxide-type products, with aldehydes as expected co-products, and helps improve the carbon balance in the initial stages of aromatic oxidation.

Radial diffusive samplers for determination of 8-h concentration of BTEX, acetone, ethanol and ozone in ambient air during a sea breeze event

Science.gov (United States)

Roukos, Joelle; Locoge, Nadine; Sacco, Paolo; Plaisance, Hervé

2011-01-01

The radial diffusive sampler Radiello ® filled with Carbograph 4 was evaluated for monitoring BTEX, ethanol and acetone concentrations for 8-hour exposure time. The sampling rates were first evaluated in an exposure chamber under standard conditions. Benzene and toluene showed the highest sampling rates with satisfactory standard deviations. Ethylbenzene and xylenes showed medium sampling rates but higher standard deviations that can be attributed to a low affinity of these compounds with the adsorbent medium for short sampling time. Acetone has a fair result because of the increase of its partial pressure in the vicinity of the adsorbent surface in the course of sampling. The Carbograph 4 adsorbent does not seem to be suitable for sampling ethanol, likely because of its high volatility. The influences of three environmental factors (temperature (T), relative humidity (RH) and concentration level (C)) on the sampling rates were also evaluated, following a fractional factorial design at two factor levels (low and high). Results were only investigated on benzene, toluene and acetone. Temperature and relative humidity are found to be the most important factors leading to variability of the benzene and toluene sampling rates. The applicability of the sampler for 8-hour sampling was demonstrated by the results of a measurement campaign carried out during a sea breeze event. Mapping of benzene, toluene and acetone concentrations showed the highest concentrations in the industrial zone following the wind direction coming from the North. Nevertheless, the sea breeze tends to reduce the spread of the industrial plumes. On the contrary, the ozone map presents the lowest concentrations at the same industrial area indicating a net consumption of ozone. The highest ozone concentrations were found in the southeastern zone suggesting a local ozone formation.

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

Science.gov (United States)

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

Formation of highly oxygenated organic molecules from aromatic compounds

Science.gov (United States)

Molteni, Ugo; Bianchi, Federico; Klein, Felix; El Haddad, Imad; Frege, Carla; Rossi, Michel J.; Dommen, Josef; Baltensperger, Urs

2018-02-01

Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) and ethylbenzene), as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl). We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

Formation of highly oxygenated organic molecules from aromatic compounds

Directory of Open Access Journals (Sweden)

U. Molteni

2018-02-01

Full Text Available Anthropogenic volatile organic compounds (AVOCs often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs, such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene and ethylbenzene, as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl. We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

Thermally enhanced bioremediation of a gasoline-contaminated aquifer using toluene oxidizing bacteria

International Nuclear Information System (INIS)

Deeb, R.; Alvarez-Cohen, L.

1994-01-01

The combined application of steam injection and vacuum extraction has proved to be very effective for the in situ remediation of a gasoline contaminated aquifer. It is expected that the steam treated zone with its near-sterile nature, increased temperature, and decreased level of contaminant concentration will provide a superior environment for enhanced bioremediation, and will favor the survival of an introduced microbial culture for the destruction of residual gasoline hydrocarbons and especially BTEX compounds (Benzene, Toluene, Ethyl benzene, and Xylene). A mixed microbial culture seeded from the pre-steamed aquifer material was enriched in a laboratory chemostat on toluene, a major gasoline aromatic. Studies were conducted to determine the optimal conditions for microbial growth and activity. Growth rate studies conducted at different temperatures revealed that cell growth was optimal at 35 C, a temperature at which the aquifer can be maintained using the existing steam injection wells. The enriched culture was shown to degrade all BTEX compounds successfully both individually and in mixtures. Substrate toxicity was observed for some of the gasoline aromatics but at concentration levels well above those found in groundwater. When cells were exposed to mixtures of BTEX compounds, the biodegradation of xylene, the most recalcitrant aromatic among BTEX compounds, was stimulated. When cells were exposed to gasoline, BTEX degradation proceeded with no apparent inhibition by gasoline aliphatics; little aliphatic degradation took place, however, suggesting the absence of monooxygenase enzymes in the mixed culture. In mixtures of both toluene and propane enriched cultures, only dioxygenase activity was observed

The impacts of ethanol-enhanced fuels on monitored natural attenuation

International Nuclear Information System (INIS)

Barker, J.; Mocanu, M.; Augustine, D.; Molson, J.

2007-01-01

A study was conducted to determine the impact of ethanol fuels on the fate and transport of gasoline hydrocarbons in groundwater. Past laboratory and field studies have shown that ethanol degrades rapidly in the subsurface and can decrease the biodegradation of other gasoline hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) through substrate competition and depletion of nutrients, oxygen and other electron receptors. In this study, 3 gasoline residuals were placed in the Borden Research Aquifer. One fuel contained 90 per cent gasoline and 10 per cent ethanol, the second contained 95 per cent ethanol and 5 per cent gasoline and the third did not have any ethanol. Ethanol from the first 2 samples dissolved rapidly. More than 60 per cent of the ethanol was biotransformed over a 150 day period of transport. Benzene and toluene were more persistent in the plume with 95 per cent ethanol, confirming that ethanol reduced their biotransformation. A 3-D numerical simulation using the BIONAPL model for gasoline dissolution, fate and transport demonstrated that benzene plumes derived from ethanol fuels may be twice as long as plumes from non-ethanol gasoline, although the benzene mass is small. It was suggested that in order to ensure effective remediation, studies should address the design and use of monitored natural attenuation. Plumes should be evaluated early in their evolution when the risk of benzene migration is highest. 12 refs., 3 tabs., 6 figs

Documentation of time-scales for onset of natural attenuation in an aquifer treated by a crude-oil recovery system

Energy Technology Data Exchange (ETDEWEB)

Ponsin, Violaine [Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement FRE, 3416 Marseille (France); French Environment and Energy Management Agency, 20 avenue de Grésillé, BP 90406 Angers Cedex 01 (France); Maier, Joachim; Guelorget, Yves [ICF Environnement, 14/30 rue Alexandre Bâtiment C F, 92635 Gennevilliers (France); Hunkeler, Daniel; Bouchard, Daniel; Villavicencio, Hakeline [Centre for Hydrogeology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel (Switzerland); Höhener, Patrick, E-mail: patrick.hohener@univ-amu.fr [Aix-Marseille Université-CNRS, Laboratoire Chimie Environnement FRE, 3416 Marseille (France)

2015-04-15

A pipeline transporting crude-oil broke in a nature reserve in 2009 and spilled 5100 m{sup 3} of oil that partly reached the aquifer and formed progressively a floating oil lens. Groundwater monitoring started immediately after the spill and crude-oil recovery by dual pump-and-skim technology was operated after oil lens formation. This study aimed at documenting the implementation of redox-specific natural attenuation processes in the saturated zone and at assessing whether dissolved compounds were degraded. Seven targeted water sampling campaigns were done during four years in addition to a routine monitoring of hydrocarbon concentrations. Liquid oil reached the aquifer within 2.5 months, and anaerobic processes, from denitrification to reduction of sulfate, were observable after 8 months. Methanogenesis appeared on site after 28 months. Stable carbon isotope analyses after 16 months showed maximum shifts in δ{sup 13}C of + 4.9 ± 0.22‰ for toluene, + 2.4 ± 0.19‰ for benzene and + 0.9 ± 0.51‰ for ethylbenzene, suggesting anaerobic degradation of these compounds in the source zone. Estimations of fluxes of inorganic carbon produced by biodegradation revealed that, in average, 60% of inorganic carbon production was attributable to sulfate reduction. This percentage tended to decrease with time while the production of carbon attributable to methanogenesis was increasing. Within the investigation time frame, mass balance estimations showed that biodegradation is a more efficient process for control of dissolved concentrations compared to pumping and filtration on an activated charcoal filter. - Highlights: • One of the world largest terrestrial oil spills is studied for 4 years. • Initially pristine aerobic groundwater turns anoxic in 8 months. • Sulfate reduction is the most important redox process thereafter. • Biologically enhanced dissolution of toluene and benzene is evidenced. • Stable carbon isotopes prove the degradation of benzene and

Formation and reactions of radical cations of substituted benzenes in aqueous media

International Nuclear Information System (INIS)

Holcman, J.

1977-08-01

Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH - , either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH - and Fe 2+ , or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH - , together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)

An overview of environmental and toxicological aspects of aromatic hydrocarbons. IV. Ethylbenzene.

Science.gov (United States)

Fishbein, L

1985-09-01

The solvent aspects of exposure to ethylbenzene are reviewed via an initial examination of the production, use, occurrence, and disposition of ethylbenzene as well as populations potentially at risk. While occupational exposure to ethylbenzene during its production and subsequent conversion to styrene is believed to be minimal, the broader occupational exposure to ethylbenzene during the production and use of 'mixed xylenes' is another area of concern. The general public can be exposed to ethylbenzene in ambient air as a result of its occurrence in motor vehicle exhaust. Additional exposure can arise in indoor environments, mostly from passive exposure to cigarette smoke. Ethylbenzene is primarily an irritant to the skin and mucous membranes and possesses narcotic properties at high concentrations.

Rapid intrinsic biodegradation of benzene, toluene, and xylenes at the boundary of a gasoline-contaminated plume under natural attenuation

Energy Technology Data Exchange (ETDEWEB)

Takahata, Yoh; Hoaki, Toshihiro [Taisei Corp., Yokohama (Japan). Civil Engineering Research Inst.; Kasai, Yuki; Watanabe, Kazuya [Marine Biotechnology Institute, Kamaishi (Japan)

2006-12-15

A groundwater plume contaminated with gasoline constituents [mainly benzene, toluene, and xylenes (BTX)] had been treated by pumping and aeration for approximately 10 years, and the treatment strategy was recently changed to monitored natural attenuation (MNA). To gain information on the feasibility of using MNA to control the spread of BTX, chemical and microbiological parameters in groundwater samples obtained inside and outside the contaminated plume were measured over the course of 73 weeks. The depletion of electron acceptors (i.e., dissolved oxygen, nitrate, and sulfate) and increase of soluble iron were observed in the contaminated zone. Laboratory incubation tests revealed that groundwater obtained immediately outside the contaminated zone (the boundary zone) exhibited much higher potential for BTX degradation than those in the contaminated zone and in uncontaminated background zones. The boundary zone was a former contaminated area where BTX were no longer detected. Denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified bacterial 16S rRNA gene fragments revealed that DGGE profiles for groundwater samples obtained from the contaminated zone were clustered together and distinct from those from uncontaminated zones. In addition, unique bacterial rRNA types were observed in the boundary zone. These results indicate that the boundary zone in the contaminant plumes served as a natural barrier for preventing the BTX contamination from spreading out. (orig.)

Assessing Emissions of Volatile Organic Componds from Landfills Gas

Directory of Open Access Journals (Sweden)

Fahime Khademi

2016-01-01

Full Text Available Background: Biogas is obtained by anaerobic decomposition of organic wastes buried materials used to produce electricity, heat and biofuels. Biogas is at the second place for power generation after hydropower and in 2000 about 6% of the world power generation was allocated to biogas. Biogas is composed of 40–45 vol% CO2, 55–65 vol% CH4, and about 1% non-methaneVOCs, and non-methane volatile organic compounds. Emission rates are used to evaluate the compliance with landfill gas emission regulations by the United States Environmental Protection Agency (USEPA. BTEX comounds affect the air quality and may be harmful to human health. Benzene, toluene, ethylbenzene and xylene isomers that are generally called BTEX compounds are the most abundant VOCs in biogas. Methods: Sampling of VOCs in biogas vents was operated passively or with Tedlar bags. 20 samples were collected from 40 wells of old and new biogas sites of Shiraz’ landfill. Immediately after sampling, the samples were transferred to the laboratory. Analysis of the samples was performed with GC-MS. Results: The results showed that in the collection of the old and new biogas sites, the highest concentration of VOCs was observed in toluene (0.85ppm followed by benzene (0.81ppm, ethylbenzene (0.13ppm and xylene (0.08ppm. Conclusion: The results of the study showed that in all samples, most available compounds in biogas vents were aromatic hydrocarbon compounds.These compounds’ constituents originate from household hazardous waste materials deposited in the landfill or from biological/chemical decomposition processes within the landfill.

Manufacture of aromatic hydrocarbons from coal hydrogenation products

Energy Technology Data Exchange (ETDEWEB)

A.S. Maloletnev; M.A. Gyul' malieva [Institute for Fossil Fuels, Moscow (Russian Federation)

2007-08-15

The manufacture of aromatic hydrocarbons from coal distillates was experimentally studied. A flow chart for the production of benzene, ethylbenzene, toluene, and xylenes was designed, which comprised the hydrogen treatment of the total wide-cut (or preliminarily dephenolized) fraction with FBP 425{sup o}C; fractional distillation of the hydrotreated products into IBP-60, 60-180, 180-300, and 300-425{sup o}C fractions; the hydro-cracking of middle fractions for increasing the yield of gasoline fractions whenever necessary; the catalytic reform of the fractions with bp up to 180{sup o}C; and the extraction of aromatic hydrocarbons.

Continued development of an atmospheric monitoring mass spectrometry system - task 2.2. Topical report, January 1, 1995 - December 31, 1995

International Nuclear Information System (INIS)

King, F.L.

1998-01-01

The objective of this project was the development of a mass spectrometric methodology applicable to the field determination of Volatile Organic Compounds (VOC's), such as BTEX components (Benzene, Toluene, Ethylbenzene, and Xylenes). A combination of chemical ionization, selective ion storage, and tandem mass spectrometry was planned to be employed with an ion trap mass spectrometry system. The Gas Chromatography Mass Spectrometry (GC-MS) interface on the ion trap system was modified to permit direct atmospheric monitoring. Through the use of tandem mass spectrometry methods the need for chromatographic separation would be eliminated reducing the overall size and complexity of the system

DNA damage by ethylbenzenehydroperoxide formed from carcinogenic ethylbenzene by sunlight irradiation

International Nuclear Information System (INIS)

Toda, Chitose; Uchida, Takafumi; Midorikawa, Kaoru; Murata, Mariko; Hiraku, Yusuke; Okamoto, Yoshinori; Ueda, Koji; Kojima, Nakao; Kawanishi, Shosuke

2003-01-01

Ethylbenzene, widely used in human life, is a non-mutagenic carcinogen. Sunlight-irradiated ethylbenzene caused DNA damage in the presence of Cu 2+ , but unirradiated ethylbenzene did not. A Cu + -specific chelator bathocuproine inhibited DNA damage and catalase showed a little inhibitory effect. The scopoletin assay revealed that peroxides and H 2 O 2 were formed in ethylbenzene exposed to sunlight. These results suggest that Cu + and alkoxyl radical mainly participate in DNA damage, and H 2 O 2 partially does. When catalase was added, DNA damage at thymine and cytosine was inhibited. Ethylbenzenehydroperoxide, identified by GC/MS analysis, induced the formation of 8-oxo-7,8-dihydro-2 ' -deoxyguanosine and caused DNA damage at consecutive guanines, as observed with cumenehydroperoxide. Equimolar concentrations of H 2 O 2 and acetophenone were produced by the sunlight-irradiation of 1-phenylethanol, a further degraded product of ethylbenzene. These results indicate a novel pathway that oxidative DNA damage induced by the peroxide and H 2 O 2 derived from sunlight-irradiated ethylbenzene may lead to expression of the carcinogenicity

Evaluation of potential toxicity from co-exposure to three CNS depressants (toluene, ethylbenzene, and xylene) under resting and working conditions using PBPK modeling.

Science.gov (United States)

Dennison, James E; Bigelow, Philip L; Mumtaz, Moiz M; Andersen, Melvin E; Dobrev, Ivan D; Yang, Raymond S H

2005-03-01

Under OSHA and American Conference of Governmental Industrial Hygienists (ACGIH) guidelines, the mixture formula (unity calculation) provides a method for evaluating exposures to mixtures of chemicals that cause similar toxicities. According to the formula, if exposures are reduced in proportion to the number of chemicals and their respective exposure limits, the overall exposure is acceptable. This approach assumes that responses are additive, which is not the case when pharmacokinetic interactions occur. To determine the validity of the additivity assumption, we performed unity calculations for a variety of exposures to toluene, ethylbenzene, and/or xylene using the concentration of each chemical in blood in the calculation instead of the inhaled concentration. The blood concentrations were predicted using a validated physiologically based pharmacokinetic (PBPK) model to allow exploration of a variety of exposure scenarios. In addition, the Occupational Safety and Health Administration and ACGIH occupational exposure limits were largely based on studies of humans or animals that were resting during exposure. The PBPK model was also used to determine the increased concentration of chemicals in the blood when employees were exercising or performing manual work. At rest, a modest overexposure occurs due to pharmacokinetic interactions when exposure is equal to levels where a unity calculation is 1.0 based on threshold limit values (TLVs). Under work load, however, internal exposure was 87%higher than provided by the TLVs. When exposures were controlled by a unity calculation based on permissible exposure limits (PELs), internal exposure was 2.9 and 4.6 times the exposures at the TLVs at rest and workload, respectively. If exposure was equal to PELs outright, internal exposure was 12.5 and 16 times the exposure at the TLVs at rest and workload, respectively. These analyses indicate the importance of (1) selecting appropriate exposure limits, (2) performing unity

Bubble points of the binary mixtures formed by ethylbenzene with some chloroaliphatics and substituted benzenes at p = 94.7 kPa

Energy Technology Data Exchange (ETDEWEB)

Vittal Prasad, T.E. [Properties Group, Chemical Engineering Laboratory, Indian Institute of Chemical Technology, Hyderabad 500 007 (India); Srinivas, M.Y. [Swami Ramananda Tirtha Institute of Science and Technology, Nalgonda 508 001 (India); Prasad, D.H.L. [Properties Group, Chemical Engineering Laboratory, Indian Institute of Chemical Technology, Hyderabad 500 007 (India)]. E-mail: dasika@iict.res.in

2006-10-15

Bubble points at a pressure of 94.7 kPa, over the entire composition range are measured for the binary mixtures formed by ethylbenzene with: 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and nitrobenzene making use of a Swietoslawski type ebulliometer. The liquid phase composition versus temperature measurements are found to be well represented by the Wilson model.

Characteristics and health effects of BTEX in a hot spot for urban pollution.

Science.gov (United States)

Dehghani, Mansooreh; Fazlzadeh, Mehdi; Sorooshian, Armin; Tabatabaee, Hamid Reza; Miri, Mohammad; Baghani, Abbas Norouzian; Delikhoon, Mahdieh; Mahvi, Amir Hossein; Rashidi, Majid

2018-07-15

This study reports a spatiotemporal characterization of toluene, benzene, ethylbenzene, and xylenes concentrations (BTEX) in an urban hot spot in Iran, specifically at an bus terminal region in Shiraz. Sampling was carried out according to NIOSH Compendium Method 1501. The inverse distance weighting (IDW) method was applied for spatial mapping. The Monte Carlo simulation technique was applied to evaluate carcinogenic and non-carcinogenic risk owing to BTEX exposure. The highest average BTEX concentrations were observed for benzene in the morning (at 7:00-9:00 A.M. local time) (26.15 ± 17.65 µg/m 3 ) and evening (at 6:00-8:00 P.M. local time) (34.44 ± 15.63 µg/m 3 ). The benzene to toluene ratios in the morning and evening were 2.02 and 3.07, respectively. The main sources of BTEX were gas stations and a municipal solid waste transfer station. The inhalation lifetime cancer risk (LTCR) for benzene in the morning and evening were 1.96 × 10 -4 and 2.49 × 10 -4 , respectively, which exceeds the recommended value by US EPA and WHO. The hazard quotient (HQ) of all these pollutants was less than 1. The results of this work have implications for public health near 'hot spots' such as IKBT where large populations are exposed to carcinogenic emissions. Copyright © 2018 Elsevier Inc. All rights reserved.

Chemical sensors of benzene and toluene based on inorganic and hybrid organic-inorganic polymers elaborated by a sol-gel process

International Nuclear Information System (INIS)

Calvo Munoz, Maria Luisa

2000-01-01

As mono-cyclic aromatic hydrocarbons (MAH) are a matter of concern in terms of pollution, and are to be monitored due to new regulations regarding air quality control, this research thesis first aims at explaining why these compounds are to be monitored, at recalling their sources, at outlining what we know about their negative impact on health and how this impact is determined, which are the means implemented to monitor these compounds and which are their drawbacks, and at recalling which requirements are defined by European directives. The author then reports a literature survey of the current technology regarding chemical sensors, and identifies the required characteristics of an ideal sensor. The author proposes a review of studied performed on sol-gel process and of inorganic polymer synthesis methods based on sol-gel process. He reports the synthesis and characterization of inorganic or hybrid organic-inorganic host matrices, monolithic or in thin layers, used to produce MAH sensors. A matrix pore local polarity study is reported. Benzene and toluene trapping is studied with respect to the polarity and thickness of the host matrix. Pollutant trapping is directly monitored by their absorption in the near-UV and visible range. The author finally reports the study of interactions between fluorescent probe molecules and pollutants, as well as the effect of an interfering gas (oxygen) on the fluorescence of probe molecules [fr

Study of the efectiveness of the mixed solvents for radically removing thiophenes from benzene and toluene by extractive rectification

Energy Technology Data Exchange (ETDEWEB)

Miroshnicenko, A.A.; Fedosyuk, A.A.

1981-01-01

A study has been made of the selectivity of solvents under the conditions of liquid-liquid equilibrium in the systems which include thiophene, benzene, toluene, the polar solvent and n-decane. The presence of the latter has maintained the heterogeneity of the mixtures being studied. The systems under consideration were drawn up in volumetric ratios. Equilibrium was studied in thermostat units. The equilibrium phases were analyzed by a special method, while the coefficient of the relative distribution of the components with respect to selectivity was calculated by the known relations. The investigations of the systems with different solvents have shown that there are functionally selective classes of extractants in which selectivity is determined by free unsubstituted functional groups of a solvent. The growth of the selectivity of solvents according to the following classes has been observed: aprotic ones with a keto group < protic ones with a hydroxyl < < unsubstituted amides of acids < sulphones < sulphoxides. To study the liquid-vapor equilibrium, use was made of the most selective extractants (including DMSO, Pyrrolidone-2, carbamide, ethylene carbamide, and NMP) which were revealed earlier in extraction investigations. Since the most selective representative of acid amides, namely, ethylene carbamide and carbamide, are solids, they were studied in mixtures with the less selective liquid solvents of NMP and pyrrolidone-2. NMP-ethylene-carbamide-water and pyrrolidone-2-ethylene carbamida-water are the most selective mixed solvents, and preference is given to the latter one.

Dispersion and exposure of sour gas flare emissions

International Nuclear Information System (INIS)

Davies, M.

2002-01-01

This presentation described the implications of flare research project findings with reference to reduced combustion efficiency, stack plume down wash and minor species. A plume model shows that reduced combustion efficiency decreases the energy available for plume rise. Reduced combustion may therefore decrease H 2 S to SO 2 conversion. Stack plume down wash can decrease plume rise under high wind speed conditions, and in extreme cases can also preclude any plume rise. Minor species include vapour phase emissions of polynuclear aromatic hydrocarbons (PAH), benzene, toluene, ethyl-benzene and xylenes (BTEX), and aldehydes. They also include particulate phase emissions such as soot and PAH. Observed concentrations of minor species were presented along with predicted vapour phase concentrations and particulate phase emissions. The standard modelling approaches used in this study included the Gaussian plume model, flame height, plume rise and dispersion. figs

Comparison of the decomposition characteristics of aromatic VOCs using an electron beam hybrid system

International Nuclear Information System (INIS)

Son, Youn-Suk; Kim, Ki-Joon; Kim, Ji-Yong; Kim, Jo-Chun

2010-01-01

We applied a hybrid technique to assess the decomposition characteristics of ethylbenzene and toluene that annexed the catalyst technique with existing electron beam (EB) technology. The removal efficiency of ethylbenzene in the EB-catalyst hybrid turned out to be 30% greater than that of EB-only treatment. We concluded that ethylbenzene was decomposed more easily than toluene by EB irradiation. We compared the independent effects of the EB-catalyst hybrid and catalyst-only methods, and observed that the efficiency of the EB-catalyst hybrid demonstrated approximately 6% improvement for decomposing toluene and 20% improvement for decomposing ethylbenzene. The G-values for ethylbenzene increased with initial concentration and reactor type: for example, the G-values by reactor type at 2800 ppmC were 7.5-10.9 (EB-only) and 12.9-25.7 (EB-catalyst hybrid). We also observed a significant decrease in by-products as well as in the removal efficiencies associated with the EB-catalyst hybrid technique.

Comparison of the decomposition characteristics of aromatic VOCs using an electron beam hybrid system

Science.gov (United States)

Son, Youn-Suk; Kim, Ki-Joon; Kim, Ji-Yong; Kim, Jo-Chun

2010-12-01

We applied a hybrid technique to assess the decomposition characteristics of ethylbenzene and toluene that annexed the catalyst technique with existing electron beam (EB) technology. The removal efficiency of ethylbenzene in the EB-catalyst hybrid turned out to be 30% greater than that of EB-only treatment. We concluded that ethylbenzene was decomposed more easily than toluene by EB irradiation. We compared the independent effects of the EB-catalyst hybrid and catalyst-only methods, and observed that the efficiency of the EB-catalyst hybrid demonstrated approximately 6% improvement for decomposing toluene and 20% improvement for decomposing ethylbenzene. The G-values for ethylbenzene increased with initial concentration and reactor type: for example, the G-values by reactor type at 2800 ppmC were 7.5-10.9 (EB-only) and 12.9-25.7 (EB-catalyst hybrid). We also observed a significant decrease in by-products as well as in the removal efficiencies associated with the EB-catalyst hybrid technique.

Impact of cigarette smoking on volatile organic compound (VOC) blood levels in the U.S. population: NHANES 2003-2004.

Science.gov (United States)

Chambers, David M; Ocariz, Jessica M; McGuirk, Maureen F; Blount, Benjamin C

2011-11-01

The impact of cigarette smoking on volatile organic compound (VOC) blood levels is studied using 2003-2004 National Health and Nutrition Examination Survey (NHANES) data. Cigarette smoke exposure is shown to be a predominant source of benzene, toluene, ethylbenzene, xylenes and styrene (BTEXS) measured in blood as determined by (1) differences in central tendency and interquartile VOC blood levels between daily smokers [≥1 cigarette per day (CPD)] and less-than-daily smokers, (2) correlation among BTEXS and the 2,5-dimethylfuran (2,5-DMF) smoking biomarker in the blood of daily smokers, and (3) regression modeling of BTEXS blood levels versus categorized CPD. Smoking status was determined by 2,5-DMF blood level using a cutpoint of 0.014 ng/ml estimated by regression modeling of the weighted data and confirmed with receiver operator curve (ROC) analysis. The BTEXS blood levels among daily smokers were moderately-to-strongly correlated with 2,5-DMF blood levels (correlation coefficient, r, ranging from 0.46 to 0.92). Linear regression of the geometric mean BTEXS blood levels versus categorized CPD showed clear dose-response relationship (correlation of determination, R(2), ranging from 0.81 to 0.98). Furthermore, the pattern of VOCs in blood of smokers is similar to that reported in mainstream cigarette smoke. These results show that cigarette smoking is a primary source of benzene, toluene and styrene and an important source of ethylbenzene and xylene exposure for the U.S. population, as well as the necessity of determining smoking status and factors affecting dose (e.g., CPD, time since last cigarette) in assessments involving BTEXS exposure. Published by Elsevier Ltd.

Bioremediation of petroleum hydrocarbons from crude oil-contaminated soil with the earthworm: Hyperiodrilus africanus.

Science.gov (United States)

Ekperusi, O A; Aigbodion, F I

2015-12-01

A study on the bioremediation potentials of the earthworm Hyperiodrilus africanus (Beddard) in soil contaminated with crude oil was investigated. Dried and sieved soils were contaminated with 5 ml each of crude oil with replicates and inoculated with earthworms and monitored daily for 12 weeks. Physicochemical parameters such as pH, total organic carbon, sulfate, nitrate, phosphate, sodium, potassium, calcium and magnesium were determined using standard procedures. Total petroleum hydrocarbon (TPH) was determined using atomic absorption spectrophotometer (AAS), while BTEX constituents and earthworms tissues were analyzed using Gas Chromatography with Flame Ionization Detector (GC-FID). The results showed that the earthworm significantly enhanced the physicochemical parameters of the contaminated soil resulting in a decrease of the total organic carbon (56.64 %), sulfate (57.66 %), nitrate (57.69 %), phosphate (57.73 %), sodium (57.69 %), potassium (57.68 %), calcium (57.69 %) and magnesium (57.68 %) except pH (3.90 %) that slightly increased. There was a significant decrease in the TPH (84.99 %), benzene (91.65 %), toluene (100.00 %), ethylbenzene (100.00 %) and xylene (100.00 %). Analyses of the tissues of the earthworm at the end of the experiment showed that the earthworms bioaccumulated/biodegraded 57.35/27.64 % TPH, 38.91/52.73 % benzene, 27.76/72.24 % toluene, 42.16/57.85 % ethylbenzene and 09.62/90.38 % xylene. The results showed that the earthworms H. africanus could be used to bioremediate moderately polluted soil with crude oil contamination in the Niger Delta region of Nigeria.

Vapor deposition of molybdenum oxide using bis(ethylbenzene) molybdenum and water

International Nuclear Information System (INIS)

Drake, Tasha L.; Stair, Peter C.

2016-01-01

Three molybdenum precursors—bis(acetylacetonate) dioxomolybdenum, molybdenum isopropoxide, and bis(ethylbenzene) molybdenum—were tested for molybdenum oxide vapor deposition. Quartz crystal microbalance studies were performed to monitor growth. Molybdenum isopropoxide and bis(ethylbenzene) molybdenum achieved linear growth rates 0.01 and 0.08 Å/cycle, respectively, using atomic layer deposition techniques. Negligible MoO_x growth was observed on alumina powder using molybdenum isopropoxide, as determined by inductively coupled plasma optical emission spectroscopy. Bis(ethylbenzene) molybdenum achieved loadings of 0.5, 1.1, and 1.9 Mo/nm"2 on alumina powder after one, two, and five cycles, respectively, using atomic layer deposition techniques. The growth window for bis(ethylbenzene) molybdenum is 135–150 °C. An alternative pulsing strategy was also developed for bis(ethylbenzene) molybdenum that results in higher growth rates in less time compared to atomic layer deposition techniques. The outlined process serves as a methodology for depositing molybdenum oxide for catalytic applications. All as-deposited materials undergo further calcination prior to characterization and testing.

Role of charge transfer and spin-orbit coupling in fluorescence quenching : a case study with oxonine and substituted benzenes

OpenAIRE

Föll, Rudolf E.; Kramer, Horst E. A.; Steiner, Ulrich

1990-01-01

Fluorescence quenching of oxonine in methanol was investigated by means of a computerized dye laser flash spectrometer for the ∆G°et, dependence of the quenching rate constant (kq) and the efficiencies of induced dye triplet formation (ηT), reduced dye radical formation (ηR), and induced internal conversion. A total of 34 substituted benzenes including 20 monohalogenated benzenes, toluenes, and anisoles were used as quenchers spanning a range of -0.85 ≤ ∆G°et ≤ 1.4 eV for a possible photoelec...

Environmental and biological applications of microplasmas

International Nuclear Information System (INIS)

Becker, K; Koutsospyros, A; Yin, S-M; Christodoulatos, C; Abramzon, N; Joaquin, J C; Brelles-Marino, G

2005-01-01

Stable glow-type discharge plasmas at elevated pressures can be generated and maintained easily when the plasma is spatially confined to cavities with critical dimensions below 1 mm ('microplasmas'). We studied the properties of several atmospheric-pressure microplasmas and their use in the remediation of volatile organic compounds (VOCs) and biological decontamination. The VOCs studied include individual prototypcal aliphatic and aromatic compounds as well as mixtures such as BTEX (benzene, toluene, ethylbenzene and xylene). The biological systems under study included individual bacteria as well as bacterial biofilms, which are highly structured communities of bacteria that are very resistant to antibiotics, germicides, and other conventional forms of destruction

THz wave sensing for petroleum industrial applications

Science.gov (United States)

Al-Douseri, Fatemah M.; Chen, Yunqing; Zhang, X.-C.

2006-04-01

We present the results of terahertz (THz) sensing of gasoline products. The frequency-dependent absorption coefficients, refractive indices, and complex dielectric constants of gasoline and xylene isomers were extracted in the spectral range from 0.5 3.0 THz. The THz spectra of gasoline (#87, #89, #93) and related BTEX (benzene, toluene, ethylbenzene, and xylene) compounds were studied by using Fourier transform infrared spectroscopy (FTIR) in the 1.5 20 THz (50 660 cm-1). The xylene isomers, which are used as antiknock agent in gasoline were determined quantitatively in gasoline in the THz range. Our investigations show the potential of THz technology for the petroleum industrial applications.

Critical issues in benzene toxicity and metabolism: the effect of interactions with other organic chemicals on risk assessment.

Science.gov (United States)

Medinsky, M A; Schlosser, P M; Bond, J A

1994-11-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several investigators have demonstrated that a combination of metabolites (hydroquinone and phenol, for example) is necessary to duplicate the hematotoxic effect of benzene. Enzymes implicated in the metabolic activation of benzene and its metabolites include the cytochrome P450 monooxygenases and myeloperoxidase. Since benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. Other organic molecules that are substrates for cytochrome P450 can inhibit the metabolism of benzene. For example, toluene has been shown to inhibit the oxidation of benzene in a noncompetitive manner. Enzyme inducers, such as ethanol, can alter the target tissue dosimetry of benzene metabolites by inducing enzymes responsible for oxidation reactions involved in benzene metabolism. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes, such as enzymatic oxidation, and deactivation processes, like conjugation and excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Methane and Benzene in Drinking-Water Wells Overlying the Eagle Ford, Fayetteville, and Haynesville Shale Hydrocarbon Production Areas.

Science.gov (United States)

McMahon, Peter B; Barlow, Jeannie R B; Engle, Mark A; Belitz, Kenneth; Ging, Patricia B; Hunt, Andrew G; Jurgens, Bryant C; Kharaka, Yousif K; Tollett, Roland W; Kresse, Timothy M

2017-06-20

Water wells (n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO 2 reduction pathway, not from thermogenic shale gas. Two samples contained methane from the fermentation pathway that could be associated with hydrocarbon degradation based on their co-occurrence with hydrocarbons such as ethylbenzene and butane. Benzene was detected at low concentrations (2500 years, indicating the benzene was from subsurface sources such as natural hydrocarbon migration or leaking hydrocarbon wells. One sample contained benzene that could be from a surface release associated with hydrocarbon production activities based on its age (10 ± 2.4 years) and proximity to hydrocarbon wells. Groundwater travel times inferred from the age-data indicate decades or longer may be needed to fully assess the effects of potential subsurface and surface releases of hydrocarbons on the wells.

Urinary trans-trans muconic acid (exposure biomarker to benzene) and hippuric acid (exposure biomarker to toluene) concentrations in Mexican women living in high-risk scenarios of air pollution.

Science.gov (United States)

Pruneda-Alvarez, Lucía G; Ruíz-Vera, Tania; Ochoa-Martínez, Angeles C; Pérez-Maldonado, Iván N

2017-11-02

This study aimed to determine t,t-muconic acid (t,t-MA; exposure biomarker for benzene) and hippuric acid (HA; exposure biomarker for toluene) concentrations in the urine of women living in Mexico. In a cross-sectional study, apparently healthy women (n = 104) were voluntarily recruited from localities with a high risk of air pollution; t,t-MA and HA in urine were quantified using a high-performance liquid chromatography (HPLC) technique. Mean urinary levels of t,t-MA ranged from 680 to 1,310 μg/g creatinine. Mean values of HA ranged from 0.38 to 0.87 g/g creatinine. In conclusion, compared to data recently reported in literature, we found high urinary levels of t,t-MA and HA in assessed women participating in this study. We therefore deem the implementation of a strategy aimed at the reduction of exposure as a necessary measure for the evaluated communities.

Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes

Science.gov (United States)

Ahuja, Ritu; Punji, Benudhar; Findlater, Michael; Supplee, Carolyn; Schinski, William; Brookhart, Maurice; Goldman, Alan S.

2011-02-01

Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products—that is, secondary alkyl arenes—with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts—specifically ‘pincer’-ligated iridium complexes—and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.

Laboratory studies on the uptake of aromatic hydrocarbons by ice crystals during vapor depositional crystal growth

Science.gov (United States)

Fries, Elke; Starokozhev, Elena; Haunold, Werner; Jaeschke, Wolfgang; Mitra, Subir K.; Borrmann, Stephan; Schmidt, Martin U.

Uptake of aromatic hydrocarbons (AH) by ice crystals during vapor deposit growth was investigated in a walk-in cold chamber at temperatures of 242, 251, and 260 K, respectively. Ice crystals were grown from ambient air in the presence of gaseous AH namely: benzene (C 6H 6), toluene (methylbenzene, C 7H 8), the C 8H 10 isomers ethylbenzene, o-, m-, p-xylene (dimethylbenzenes), the C 9H 12 isomers n-propylbenzene, 4-ethyltoluene, 1,3,5-trimethylbenzene (1,3,5-TMB), 1,2,4-trimethylbenzene (1,2,4-TMB), 1,2,3-trimethylbenzene (1,2,3-TMB), and the C 10H 14 compound tert.-butylbenzene. Gas-phase concentrations calculated at 295 K were 10.3-20.8 μg m -3. Uptake of AH was detected by analyzing vapor deposited ice with a very sensitive method composed of solid-phase micro-extraction (SPME), followed by gas chromatography/mass spectrometry (GC/MS). Ice crystal size was lower than 1 cm. At water vapor extents of 5.8, 6.0 and 8.1 g m -3, ice crystal shape changed with decreasing temperatures from a column at a temperature of 260 K, to a plate at 251 K, and to a dendrite at 242 K. Experimentally observed ice growth rates were between 3.3 and 13.3×10 -3 g s -1 m -2 and decreased at lower temperatures and lower value of water vapor concentration. Predicted growth rates were mostly slightly higher. Benzene, toluene, ethylbenzene, and xylenes (BTEX) were not detected in ice above their detection limits (DLs) of 25 pg g ice-1 (toluene, ethylbenzene, xylenes) and 125 pg g ice-1 (benzene) over the entire temperature range. Median concentrations of n-propylbenzene, 4-ethyltoluene, 1,3,5-TMB, tert.-butylbenzene, 1,2,4-TMB, and 1,2,3-TMB were between 4 and 176 pg g ice-1 at gas concentrations of 10.3-10.7 μg m -3 calculated at 295 K. Uptake coefficients ( K) defined as the product of concentration of AH in ice and density of ice related to the product of their concentration in the gas phase and ice mass varied between 0.40 and 10.23. K increased with decreasing temperatures. Values of

PERFORMANCE INDICES TO DESIGN A MULTICOMPONENT BATCH DISTILLATION COLUMN USING A SHORTCUT METHOD

Directory of Open Access Journals (Sweden)

A. Narvaes-Garcia

2015-06-01

Full Text Available AbstractIn this paper, three quality or performance indices (Luyben's capacity factor, total annual costs, and annual profit were applied for the design of a batch distillation column working at variable reflux. This work used the Fenske-Underwood-Gilliland short-cut method to solve a problem of four components (benzene, toluene, ethyl-benzene, and ortho-xylene that needed to be separated and purified to a mole fraction of 0.97 or better. The performance of the system was evaluated using distillation columns with 10, 20, 30, 40 and 50 theoretical stages with a boil-up vapor flow set at 100 kmol/h. It was found that the annual profit was the best quality index, while the best case for variable reflux was the column with 50 stages. It was confirmed that the best case always required a reflux ratio close to the minimum.

Highly Solvent Tolerance in Serratia marcescens IBBPo15

Directory of Open Access Journals (Sweden)

Mihaela Marilena Stancu

Full Text Available ABSTRACT The aim of this study was to investigate the solvent tolerance mechanisms in Serratia marcescens strain IBBPo15 (KT315653. Serratia marcescens IBBPo15 exhibited remarkable solvent-tolerance, being able to survive in the presence of high concentrations (above 40% of toxic organic solvents, such as cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. S. marcescens IBBPo15 produced extracellular protease and the enzyme production decreased in cells exposed to 5% cyclohexane, n-hexane, toluene, styrene, and ethylbenzene, as compared with the control and n-decane exposed cells. S. marcescens IBBPo15 cells produced carotenoid pigments and alteration of pigments profile (i.e., phytoene, lycopene were observed in cells exposed to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. The exposure of S. marcescens IBBPo15 cells to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, ethylbenzene induced also changes in the intracellular (e.g., 50 kDa protein and extracellular (e.g., 39, 41, 43, 53, 110 kDa proteins proteins profile. Significant RAPD, ARDRA, rep-PCR and PCR pattern modifications were not observed in DNA extracted from S. marcescens IBBPo15 cells exposed to 5% cyclohexane, n-hexane, n-decane, toluene, styrene, and ethylbenzene. Though only HAE1 and acrAB genes were detected in the genome of S. marcescens IBBPo15 cells, the unspecific amplification of other fragments being observed also when the primers for ompF and recA genes were used.

Methane from benzene in argon dielectric barrier discharge

International Nuclear Information System (INIS)

Das, Tomi Nath; Dey, G.R.

2013-01-01

Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

Combinations of Aromatic and Aliphatic Radiolysis.

Science.gov (United States)

LaVerne, Jay A; Dowling-Medley, Jennifer

2015-10-08

The production of H(2) in the radiolysis of benzene, methylbenzene (toluene), ethylbenzene, butylbenzene, and hexylbenzene with γ-rays, 2-10 MeV protons, 5-20 MeV helium ions, and 10-30 MeV carbon ions is used as a probe of the overall radiation sensitivity and to determine the relative contributions of aromatic and aliphatic entities in mixed hydrocarbons. The addition of an aliphatic side chain with progressively from one to six carbon lengths to benzene increases the H(2) yield with γ-rays, but the yield seems to reach a plateau far below that found from a simple aliphatic such as cyclohexane. There is a large increase in H(2) with LET (linear energy transfer) for all of the substituted benzenes, which indicates that the main process for H(2) formation is a second-order process and dominated by the aromatic entity. The addition of a small amount of benzene to cyclohexane can lower the H(2) yield from the value expected from a simple mixture law. A 50:50% volume mixture of benzene-cyclohexane has essentially the same H(2) yield as cyclohexylbenzene at a wide variation in LET, suggesting that intermolecular energy transfer is as efficient as intramolecular energy transfer.

Are biogenic emissions a significant source of summertime atmospheric toluene in the rural Northeastern United States?

Directory of Open Access Journals (Sweden)

M. L. White

2009-01-01

Full Text Available Summertime atmospheric toluene enhancements at Thompson Farm in the rural northeastern United States were unexpected and resulted in a toluene/benzene seasonal pattern that was distinctly different from that of other anthropogenic volatile organic compounds. Consequently, three hydrocarbon sources were investigated for potential contributions to the enhancements during 2004–2006. These included: (1 increased warm season fuel evaporation coupled with changes in reformulated gasoline (RFG content to meet US EPA summertime volatility standards, (2 local industrial emissions and (3 local vegetative emissions. The contribution of fuel evaporation emission to summer toluene mixing ratios was estimated to range from 16 to 30 pptv d⁻¹, and did not fully account for the observed enhancements (20–50 pptv in 2004–2006. Static chamber measurements of alfalfa, a crop at Thompson Farm, and dynamic branch enclosure measurements of loblolly pine trees in North Carolina suggested vegetative emissions of 5 and 12 pptv d⁻¹ for crops and coniferous trees, respectively. Toluene emission rates from alfalfa are potentially much larger as these plants were only sampled at the end of the growing season. Measured biogenic fluxes were on the same order of magnitude as the influence from gasoline evaporation and industrial sources (regional industrial emissions estimated at 7 pptv d⁻¹ and indicated that local vegetative emissions make a significant contribution to summertime toluene enhancements. Additional studies are needed to characterize the variability and factors controlling toluene emissions from alfalfa and other vegetation types throughout the growing season.

Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks

Energy Technology Data Exchange (ETDEWEB)

Gagnaire, Francois; Langlais, Cristina; Grossmann, Stephane; Wild, Pascal [Institut National de Recherche et de Securite, Departement Polluants et Sante, Vandoeuvre Cedex (France)

2007-02-15

Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene. (orig.)

Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks.

Science.gov (United States)

Gagnaire, François; Langlais, Cristina; Grossmann, Stéphane; Wild, Pascal

2007-02-01

Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene.

Volatile organic compounds speciation and their influence on ozone formation potential in an industrialized urban area in Brazil.

Science.gov (United States)

Galvão, Elson Silva; Santos, Jane Meri; Reis Junior, Neyval Costa; Stuetz, Richard Michael

2016-09-01

Speciation and the influence on the ozone formation potential (OFP) from volatile organic compounds (VOCs) have been studied between February June 2013 in Vitória, ES, Brazil. Passive samplers were installed at three air-quality monitoring stations and a total of 96 samplings were collected. A total of 78 VOCs were characterized by gas chromatograph-mass spectrometer. The predominant group was organic acids, followed by alcohols and substituted aromatics and 14 precursor species were quantified. An analysis correlating concentrations with wind direction was conducted to identify possible sources. The OFP was calculated applying the scale of maximum incremental reactivity proposed by Carter.[ 23 ] Ozone precursors with the greatest OFP such as undecane, toluene, ethylbenzene and m, p-xylene compounds were the most abundant with means of 0.855, 0.365, 0.259 and 0.289 µg m(-3), respectively. The benzene, toluene, ethylbenzene and xylene (BTEX) group was found below the limits considered harmful to the health of the population living in Vitória. The OFP calculated for the precursors group was 22.55 µg m(-3) for the rainy season and 32.11 µg m(-3) for the dry season. The VOC/NOx ratio in Vitória is approximately 1.71, indicating that the region has a VOC-limiting condition for the production of ozone.

Biodegradation of volatile organic compounds by five fungal species

Energy Technology Data Exchange (ETDEWEB)

Qi, B.; Moe, W.M. [Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA (United States); Kinney, K.A. [Dept. of Civil Engineering, Univ. of Texas, Austin (United States)

2002-07-01

Five fungal species, Cladosporium resinae (ATCC 34066), Cladosporium sphaerospermum (ATCC 200384), Exophiala lecanii-corni (CBS 102400), Mucor rouxii (ATCC 44260), and Phanerochaete chrysosporium (ATCC 24725), were tested for their ability to degrade nine compounds commonly found in industrial off-gas emissions. Fungal cultures inoculated on ceramic support media were provided with volatile organic compounds (VOCs) via the vapor phase as their sole carbon and energy sources. Compounds tested included aromatic hydrocarbons (benzene, ethylbenzene, toluene, and styrene), ketones (methyl ethyl ketone, methyl isobutyl ketone, and methyl propyl ketone), and organic acids (n-butyl acetate, ethyl 3-ethoxypropionate). Experiments were conducted using three pH values ranging from 3.5 to 6.5. Fungal ability to degrade each VOC was determined by observing the presence or absence of visible growth on the ceramic support medium during a 30-day test period. Results indicate that E. lecanii-corni and C. sphaerospermum can readily utilize each of the nine VOCs as a sole carbon and energy source. P. chrysosporium was able to degrade all VOCs tested except for styrene under the conditions imposed. C. resinae was able to degrade both organic acids, all of the ketones, and some of the aromatic compounds (ethylbenzene and toluene); however, it was not able to grow utilizing benzene or styrene under the conditions tested. With the VOCs tested, M. rouxii produced visible growth only when supplied with n-butyl acetate or ethyl 3-ethoxypropionate. Maximum growth for most fungi was observed at a pH of approximately 5.0. The experimental protocol utilized in these studies is a useful tool for assessing the ability of different fungal species to degrade gas-phase VOCs under conditions expected in a biofilter application. (orig.)

Organic compound emissions from a landfarm used for oil and gas solid waste disposal.

Science.gov (United States)

Lyman, Seth N; Mansfield, Marc L

2018-04-13

Solid or sludgy hydrocarbon waste is a by-product of oil and gas exploration and production. One commonly used method of disposing of this waste is landfarming. Landfarming involves spreading hydrocarbon waste on soils, tilling it into the soil, and allowing it to biodegrade. We used a dynamic flux chamber to measure fluxes of methane, a suite of 54 nonmethane hydrocarbons, and light alcohols from an active and a remediated landfarm in eastern Utah. Fluxes from the remediated landfarm were not different from a polytetrafluoroethylene (PTFE) sheet or from undisturbed soils in the region. Fluxes of methane, total nonmethane hydrocarbons, and alcohols from the landfarm in active use were 1.41 (0.37, 4.19) (mean and 95% confidence limits), 197.90 (114.72, 370.46), and 4.17 (0.03, 15.89) mg m -2  hr -1 , respectively. Hydrocarbon fluxes were dominated by alkanes, especially those with six or more carbons. A 2-ha landfarm with fluxes of the magnitude we observed in this study would emit 95.3 (54.3, 179.7) kg day -1 of total hydrocarbons, including 11.2 (4.3, 33.9) kg day -1 of BTEX (benzene, toluene, ethylbenzene, and xylenes). Solid and sludgy hydrocarbon waste from the oil and gas industry is often disposed of by landfarming, in which wastes are tilled into soil and allowed to decompose. We show that a land farm in Utah emitted a variety of organic compounds into the atmosphere, including hazardous air pollutants and compounds that form ozone. We calculate that a 2-ha landfarm facility would emit 95.0 ± 66.0 kg day -1 of total hydrocarbons, including 11.1 ± 1.5 kg day -1 of BTEX (benzene, toluene, ethylbenzene, and xylenes).

Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

DEFF Research Database (Denmark)

Emmerling, Uwe; Rasmussen, Peter

1998-01-01

a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC......Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...

Excess enthalpies of ternary mixtures of (oxygenated additives + aromatic hydrocarbon) mixtures in fuels and bio-fuels: (Dibutyl-ether + 1-propanol + benzene), or toluene, at T = (298.15 and 313.15) K

International Nuclear Information System (INIS)

Alaoui, Fatima E.M.; Aguilar, Fernando; González-Fernández, María Jesús; Dakkach, Mohamed; Montero, Eduardo A.

2015-01-01

Highlights: • New excess enthalpy data for ternary mixtures of (dibutyl ether + aromatic hydrocarbon + 1-propanol) are reported. • 2 ternary systems at T = (298.15 and 313.15) K were measured by means of an isothermal flow calorimeter. • 230 data were fitted to a Redlich–Kister rational equation. • Intermolecular and association effects involved in these systems have been discussed. - Abstract: New experimental excess molar enthalpy data of the ternary systems (dibutyl ether + 1-propanol + benzene, or toluene), and the corresponding binary systems at T = (298.15 and 313.15) K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and ternary systems show endothermic character at both temperatures. The experimental data for the systems have been fitted using the Redlich–Kister rational equation. Considerations with respect the intermolecular interactions amongst ether, alcohol and hydrocarbon compounds are presented

Determination of BTEX in surface and ground waters at Centro Experimental Aramar area

Energy Technology Data Exchange (ETDEWEB)

Matoso, Erika; Oliveira, Rando M. de; Segre, Nádia, E-mail: ematoso@hotmail.com [Centro Tecnológico da Marinha em São Paulo (CEA/CTMSP), Iperó, SP (Brazil). Centro Experimental Aramar

2017-07-01

The mixture of the monocyclic aromatic compounds benzene, toluene, ethylbenzene and xylene isomers is defined as BTEX. The presence of BTEX in the environment is regularly associated with petroleum and its byproducts leakages or industrial effluent discharge. BTEX may cause serious problems to human and animal health. Human exposure to these aromatic compounds can lead to eye and skin irritation, central nervous system weakening and bone marrow depression. According to World Health Organization (WHO) benzene can cause cancer development. A new unit process in Centro Experimental Aramar (CEA) using BTEX-containing products will be launched shortly. Therefore, BTEX monitoring will be necessary since effluents release in Brazil is controlled by CONAMA regulations. Besides, as these compounds has never been evaluated in CEA, it is important to provide knowledge on the current BTEX concentration, in order to establish pre-operational values in CEA region and nearby. The CONAMA regulations for BTEX in superficial waters sets very low limits (such as 0,002 mg L- 1 for toluene and 0,005 mg L-1 for benzene). For this reason, it was developed in this work an analytical method by Headspace-GC-MS to achieve these values. The figures of merit determined were limit of detection (LOD), limit of quantification (LOQ), precision and accuracy. BTEX was analyzed in superficial waters from three different sampling points at Ipanema River and ground water collected in eight different sampling points. All sampling points were located a ratio 10 km radius from CEA. (author)

Determination of BTEX in surface and ground waters at Centro Experimental Aramar area

International Nuclear Information System (INIS)

Matoso, Erika; Oliveira, Rando M. de; Segre, Nádia

2017-01-01

The mixture of the monocyclic aromatic compounds benzene, toluene, ethylbenzene and xylene isomers is defined as BTEX. The presence of BTEX in the environment is regularly associated with petroleum and its byproducts leakages or industrial effluent discharge. BTEX may cause serious problems to human and animal health. Human exposure to these aromatic compounds can lead to eye and skin irritation, central nervous system weakening and bone marrow depression. According to World Health Organization (WHO) benzene can cause cancer development. A new unit process in Centro Experimental Aramar (CEA) using BTEX-containing products will be launched shortly. Therefore, BTEX monitoring will be necessary since effluents release in Brazil is controlled by CONAMA regulations. Besides, as these compounds has never been evaluated in CEA, it is important to provide knowledge on the current BTEX concentration, in order to establish pre-operational values in CEA region and nearby. The CONAMA regulations for BTEX in superficial waters sets very low limits (such as 0,002 mg L- 1 for toluene and 0,005 mg L-1 for benzene). For this reason, it was developed in this work an analytical method by Headspace-GC-MS to achieve these values. The figures of merit determined were limit of detection (LOD), limit of quantification (LOQ), precision and accuracy. BTEX was analyzed in superficial waters from three different sampling points at Ipanema River and ground water collected in eight different sampling points. All sampling points were located a ratio 10 km radius from CEA. (author)

Real-time monitoring of respiratory absorption factors of volatile organic compounds in ambient air by proton transfer reaction time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhonghui [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Yanli [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Yan, Qiong [Department of Respiratory Diseases, Guangzhou No. 12 People' s Hospital, Guangzhou 510620 (China); Zhang, Zhou [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wang, Xinming, E-mail: wangxm@gig.ac.cn [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)

2016-12-15

Respiratory absorption factors (AFs) are essential parameters in the evaluation of human health risks from toxic volatile organic compounds (VOCs) in ambient air. A method for the real time monitoring of VOCs in inhaled and exhaled air by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) has been developed to permit the calculation of respiratory AFs of VOCs. Isoprene was found to be a better breath tracer than O{sub 2}, CO{sub 2}, humidity, or acetone for distinguishing between the expiratory and inspiratory phases, and a homemade online breath sampling device with a buffer tube was used to optimize signal peak shapes. Preliminary tests with seven subjects exposed to aromatic hydrocarbons in an indoor environment revealed mean respiratory AFs of 55.0%, 55.9%, and 66.9% for benzene, toluene, and C8-aromatics (ethylbenzene and xylenes), respectively. These AFs were lower than the values of 90% or 100% used in previous studies when assessing the health risks of inhalation exposure to hazardous VOCs. The mean respiratory AFs of benzene, toluene and C8-aromatics were 66.5%, 70.2% and 82.3% for the three female subjects; they were noticeably much higher than that of 46.4%, 45.2% and 55.3%, respectively, for the four male subjects.

Characterization of selected volatile organic compounds, polycyclic aromatic hydrocarbons and carbonyl compounds at a roadside monitoring station

Science.gov (United States)

Ho, K. F.; Lee, S. C.; Chiu, Gloria M. Y.

Volatile organic compounds (VOCs), PAHs and carbonyl compounds are the major toxic components in Hong Kong. Emissions from motor vehicles have been one of the primary pollution sources in the metropolitan areas throughout Hong Kong for a long time. A 1-yr monitoring program for VOCs, PAHs and carbonyl compounds had been performed at a roadside urban station at Hong Kong Polytechnic University in order to determine the variations and correlations of each selected species (VOCs, PAHs and carbonyl compounds). This study is aimed to analyze toxic volatile organic compounds (benzene, toluene, ethylbenzene and xylene), two carbonyl compounds (formaldehyde, acetaldehyde), and selective polycyclic aromatic hydrocarbons. The monitoring program started from 16 April 1999 to 30 March 2000. Ambient VOC concentrations, many of which originate from the same sources as particulate PAHs and carbonyls compounds, show significant quantities of benzene, toluene and xylenes. Correlations and multivariate analysis of selected gaseous and particulate phase organic pollutants were performed. Source identification by principle component analysis and hierarchical cluster analysis allowed the identification of four sources (factors) for the roadside monitoring station. Factor 1 represents the effect of diesel vehicle exhaust. Factor 2 shows the contribution of aromatic compounds. Factor 3 explains photochemical products—formaldehyde and acetaldehyde. Factor 4 explains the effect of gasoline vehicle exhaust.

Conceptual process design of extractive distillation processes for ethylbenzene/styrene separation

NARCIS (Netherlands)

Jongmans, Mark; Hermens, E.; Raijmakers, M.; Maassen, J.I.W.; Schuur, Boelo; de Haan, A.B.

2012-01-01

In the current styrene production process the distillation of the close-boiling ethylbenzene/styrene mixture to obtain an ethylbenzene impurity level of 100 ppm in styrene accounts for 75–80% of the energy requirements. The future target is to reach a level of 1–10 ppm, which will increase the

HYDROCARBON-DEGRADING BACTERIA AND SURFACTANT ACTIVITY

Energy Technology Data Exchange (ETDEWEB)

Brigmon, R; Topher Berry, T; Grazyna A. Plaza, G; jacek Wypych, j

2006-08-15

Fate of benzene ethylbenzene toluene xylenes (BTEX) compounds through biodegradation was investigated using two different bacteria, Ralstonia picketti (BP-20) and Alcaligenes piechaudii (CZOR L-1B). These bacteria were isolated from extremely polluted petroleum hydrocarbon contaminated soils. PCR and Fatty Acid Methyl Ester (FAME) were used to identify the isolates. Biodegradation was measured using each organism individually and in combination. Both bacteria were shown to degrade each of the BTEX compounds. Alcaligenes piechaudii biodegraded BTEXs more efficiently while mixed with BP-20 and individually. Biosurfactant production was observed by culture techniques. In addition 3-hydroxy fatty acids, important in biosurfactant production, was observed by FAME analysis. In the all experiments toluene and m+p- xylenes were better growth substrates for both bacteria than the other BTEX compounds. In addition, the test results indicate that the bacteria could contribute to bioremediation of aromatic hydrocarbons (BTEX) pollution increase biodegradation through the action by biosurfactants.

Final Technical Report - Autothermal Styrene Manufacturing Process with Net Export of Energy

Energy Technology Data Exchange (ETDEWEB)

Trubac, Robert , E.; Lin, Feng; Ghosh, Ruma: Greene, Marvin

2011-11-29

The overall objectives of the project were to: (a) develop an economically competitive processing technology for styrene monomer (SM) that would reduce process energy requirements by a minimum 25% relative to those of conventional technology while achieving a minimum 10% ROI; and (b) advance the technology towards commercial readiness. This technology is referred to as OMT (Oxymethylation of Toluene). The unique energy savings feature of the OMT technology would be replacement of the conventional benzene and ethylene feedstocks with toluene, methane in natural gas and air or oxygen, the latter of which have much lower specific energy of production values. As an oxidative technology, OMT is a net energy exporter rather than a net energy consumer like the conventional ethylbenzene/styrene (EB/SM) process. OMT plants would ultimately reduce the cost of styrene monomer which in turn will decrease the costs of polystyrene making it perhaps more cost competitive with competing polymers such as polypropylene.

Atmospheric benzene observations from oil and gas production in the Denver-Julesburg Basin in July and August 2014

Science.gov (United States)

Halliday, Hannah S.; Thompson, Anne M.; Wisthaler, Armin; Blake, Donald R.; Hornbrook, Rebecca S.; Mikoviny, Tomas; Müller, Markus; Eichler, Philipp; Apel, Eric C.; Hills, Alan J.

2016-09-01

High time resolution measurements of volatile organic compounds (VOCs) were collected using a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the Platteville Atmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (O&NG) development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's "Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality" (DISCOVER-AQ) field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO.

Effect of temperature on the volumetric properties of (cyclohexanone+an aromatic hydrocarbon)

International Nuclear Information System (INIS)

Wang Haijun; Liu Wei; Wu Yonghua

2004-01-01

The excess molar volume VmE of (cyclohexanone+benzene, or toluene, or ethylbenzene, or styrene) were obtained from the densities measured by means of a vibrating-tube densimeter over the whole composition range at temperatures (293.15, 303.15, 313.15, 323.15, 333.15, 343.15, 353.15) K and atmospheric pressure. The excess molar volume VmE provide the temperature dependence of VmE in the temperature range of (293 to 353) K. The VmE results were correlated using the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. It was found that the VmE in the systems studied increase with rising temperature

Utilizing the fluidized bed to initiate water treatment on site

International Nuclear Information System (INIS)

Ahmadvand, H.; Germann, G.; Gandee, J.P.; Buehler, V.T.

1995-01-01

Escalating wastewater disposal costs coupled with enforcement of stricter regulations push industrial sites previously without water treatment to treat on site. These sites, inexperienced in water treatment, require a treatment technology that is easily installed, operated, and maintained. The aerobic granular activated carbon (GAC) fluidized bed incorporates biological and adsorptive technologies into a simple, cost-effective process capable of meeting strict effluent requirements. Two case studies at industrial sites illustrate the installation and operation of the fluidized bed and emphasize the ability to use the fluidized bed singularly or as an integral component of a treatment system capable of achieving treatment levels that allow surface discharge and reinjection. Attention is focused on BTEX (benzene, toluene, ethylbenzene, and xylenes)

Procedure manual: protocol for regulation of petroleum hydrocarbons in water under the special waste and contaminated sites regulation

International Nuclear Information System (INIS)

Evans, P.; Partridge, E.

2002-05-01

This document details the regulation governing numerical standards for petroleum hydrocarbons in water under the special waste and contaminated sites regulations of British Columbia. Groundwater containing benzene, toluene, ethylbenzene or xylenes in excess of the leachate standards is exempted from the regulatory regime of the Special Waste Regulation. The document contains a description of the conditions that apply to the management of petroleum hydrocarbons in water at contaminated sites. Some definitions are included, followed by an overview of the regulation. The third section deals with authorization and mandatory conditions, while additional requirements that might apply are enumerated in section four. This protocol directly affects the Environmental Management, and the Environmental Protection Regional Operations organizations. 1 tab

Results of groundwater monitoring in some 'hot spots' in Serbia in period 1999-2000

International Nuclear Information System (INIS)

Hirsbrunner, W.; Komarcic, M.

2002-01-01

Swiss Disaster Relief (SDR), part of Swiss Agency for Development and Cooperation (SDC) took over the program on a bilateral agreement with the Federal Republic of Yugoslavia (FRY) in 5 towns. Investigation covered ge-neral parameters (conductivity, KMnO 4 demand, TOC-total organic carbon, total hydrocarbons, mineral oil and phenols), heavy metals (As, Hg, Pb, Zn, V and Cu), polycyclic aromatic hydrocarbons (PAH) (total and main components), PCB-polychlorinated biphenyls (total and main components), BTEX (benzene, toluene, ethylbenzene and xylenes) and chlorinated hydrocarbons. Duration of the program was defined for one year, from November 1999 to the end of the year 2000, and samples were collected every two months. Common findings for all locations are presented

The East Garrington Trench and Gate system: it works

International Nuclear Information System (INIS)

Bowles, M.; Rimbey, S.; Bentley, L.; Thomas, D.; Hoyne, B.

1997-01-01

A 'trench and gate' system (a modification of the 'funnel and gate' system) has been installed at the Amoco-operated East Garrington gas plant in Alberta to provide long-term remediation for treating contaminated groundwater plumes hosted by low hydraulic conductivity sediments. Modification to the funnel and gate design includes an up gradient high hydraulic conductivity trench and a down gradient infiltration gallery which was found to be effective in biodegrading BTEX (benzene, toluene, ethylbenzene and xylene) compounds. A comprehensive monitoring program was set up to characterize the groundwater flow system. Several indigenous hydrocarbon degrading organisms have been identified. It was shown that locally, under aerobic conditions, phosphorus was the limiting nutrient. 13 refs., 3 tabs., 10 figs

Catalytic oxidation of volatile organic compounds (n-hexane, benzene, toluene, o-xylene promoted by cobalt catalysts supported on γ-Al2O3-CeO2

Directory of Open Access Journals (Sweden)

R. Balzer

2014-09-01

Full Text Available Cobalt catalysts supported on γ-alumina, ceria and γ-alumina-ceria, with 10 or 20%wt of cobalt load, prepared by the wet impregnation method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission transmission electron microscopy (FETEM, N2 adsorption-desorption isotherms (BET/BJH methods, energy-dispersive X-ray spectroscopy (EDX, X-ray photoemission spectroscopy (XPS, O2-chemisorption and temperature programmed reduction (TPR were used to promote the oxidation of volatile organic compounds (n-hexane, benzene, toluene and o-xylene. For a range of low temperatures (50-350 °C, the activity of the catalysts with a higher cobalt load (20% wt was greater than that of the catalysts with a lower cobalt load (10% wt. The Co/γ-Al2O3-CeO2 catalytic systems presented the best performances. The results obtained in the characterization suggest that the higher catalytic activity of the Co20/γ-Al2O3-CeO2 catalyst may be attributed to the higher metal content and amount of oxygen vacancies, as well as the effects of the interaction between the cobalt and the alumina and cerium oxides.

Removal of benzene under acidic conditions in a controlled Trickle Bed Air Biofilter.

Science.gov (United States)

Hassan, Ashraf Aly; Sorial, George A

2010-12-15

Trickle Bed Air Biofilters (TBABs) are considered to be economical and environmental-friendly for treatment of Volatile Organic Compounds (VOCs). Hydrophilic VOCs are easily degradable while hydrophobic ones pose a great challenge for adequate treatment due to the transfer of the VOC to the liquid phase. In this study the utilization of acidic pH is proposed for the treatment of benzene vapors. The acidic pH would encourage the growth of fungi as the main consortium. A TBAB operated at pH 4 was used for the treatment of an air stream contaminated with benzene under different loading rates ranging from 37 to 76.8 g/(m(3)h). The purpose of introducing fungi was to compare the performance with traditional TBAB operating under neutral pH in order to assess the biodegradation of benzene in mixtures with other compounds favoring acidic conditions. The experimental plan was designed to assess long-term performance with emphasis based on different benzene loading rates, removal efficiency with TBAB depth, and carbon mass balance closure. At benzene loading rate of 64 g/(m(3)h), the removal efficiency was 90%. At the maximum loading rate of 77 g/(m(3)h), the removal efficiency was 75% marking the maximum elimination capacity for the TBAB at 58.8 g/(m(3)h). Operating at acidic pH successfully supported the degradation of benzene in TBAB. It is worthwhile to note that benzene appears in mixtures with n-hexane and toluene, which are reported to be better degraded under such conditions. Copyright © 2010 Elsevier B.V. All rights reserved.

Assessment of the BTEX concentrations and health risk in urban nursery schools in Gliwice, Poland

Directory of Open Access Journals (Sweden)

Anna Mainka

2016-12-01

Full Text Available Indoor air quality (IAQ in nursery school is believed to be different from elementary school. Moreover, younger children are more vulnerable to air pollution than higher grade children because they spend more time indoors, and their immune systems and bodies are less mature. The purpose of this study was to compare the concentrations of the monoaromatic volatile benzene, toluene, ethylbenzene m,p-xylene and o-xylene (BTEX in urban nursery schools located in Gliwice, Poland. The nursery schools were chosen to include areas with different urbanization and traffic density characteristics in order to gather a more diverse picture of exposure risks in the various regions of the city. BTEX were sampled during winter and spring seasons in older and younger children classrooms. The samples were thermally desorbed (TD and then analyzed with use of gas chromatography (GC. In addition, outdoor measurements were carried out in the playground at each nursery school. BTEX quantification, indoor/outdoor concentration, and correlation coefficients were used to identify pollutant sources. Elevated levels of o-xylene and ethylbenzene were found in all monitored classrooms during the winter season. Outdoor concentrations were lower than indoors for each classroom. Indicators based on health risk assessment for chronic health effects associated with carcinogenic benzene or non-carcinogenic BTEX were proposed to rank sites according to their hazard level.

Crystal dimension of ZSM-5 influences on para selective disproportionation of ethylbenzene.

Science.gov (United States)

Hariharan, Srinivasan; Palanichamy, Muthaiahpillai

2014-03-01

Crystal size and crystal dimensions are vital role in shape selective feature. Para selective disproportionation of EthylBenzene (Dip-EB) was investigated over ZSM-5 synthesized in acidic medium. The catalysts were prepared by hydrothermal process with various Si/Al ratios (50, 75 and 100) using fluoride ion precursor. This fluoride ion precursor dissolves the ZSM-5 nutrients below it neutral pH between 4 and 6. The synthesized material was subjected into various physico chemical characterizations such as XRD, SEM, TGA and BET analyses. The XRD patterns showed high crystalline nature and their resulting SEM images were also indicate thin prismatic crystals of large dimension compared with alkaline medium synthesized one. The BET results earned good textural property. Catalytic activity of vapor phase Dip-EB was carried out between 523 and 673 K. As their result, diethylbenzene (DEB) isomers were obtained, but para selective Diethylbenzene (p-DEB) was observed higher than others. The high selectivity towards p-DEB was due to large crystal dimension of ZSM-5 catalysts synthesized in fluoride medium. Hence it is good commercial application for petrochemical feed stock production.

Temperature Dependences for the Reactions of Ar+, O2+, and C7H7+ with Toluene and Ethylbenzene

Science.gov (United States)

2013-07-01

Pi-Pi-Interactions; Flowing Afterglow; Charge-Transfer; Gas -Phase; Electronic-Structure; Mass-Spectrometry; Gaseous Benzene; Tropylium Ion; Cations...filter and the desired mass ion was selected. he ions enter the flow tube through a Venturi inlet and are car- ied downstreamby a heliumbuffer. After...9 cm of the flow tube, and subsequently the flow was sampled hrough a small orifice in a rounded nose cone. The remainder of he flow was pumped away

Study of the catalytic system, ethylbenzene-aluminum bromide, by the methods of NMR and EPR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lipovich, V.G.; Bazhenova, A.P.; Kalabin, G.A.; Laperdina, T.G.; Latysheva, L.E.; Saraev, V.V.

1981-01-01

By the methods of NMR, EPR, and deuterium exchange it was shown that in the presence of air or oxygen in the system, ethylbenzene (I)-A1Br/sub 3/, disproportionation processes are activated, as a result of which in the /sup 1/H and /sup 13/ C NMR spectra new signals for the alkyl group of I and a signal for benzene alone appear. With accumulation in the composite layer of the catalytic system of a sufficient quantity of triethylbenzene, its protonation occurs with formation of the 2,4,6-triethylbenzenium ion. Interconversion of the two types of EPR signals, registerable on admission of air into the I-A1Br/sub 3/ system, occurs because of positional isomerization of the forming di- and triethylbenzenes. It was shown that in the presence of air in the system I-isopropylbenzene-A1Br/sub 3/, the degree of deuterium exchange between a-positions of alkyl groups is increased by 10-15% by comparison with the degassed system.

Analysis of air toxics, criteria pollutants and meteorological monitoring data in Valdez, Alaska

International Nuclear Information System (INIS)

Stopenhagen, K.W.; Kester, R.A.; Caniparoli, D.G.; Gravely, R.J.

1991-01-01

An ambient monitoring network began operation in Valdez, Alaska in August 1990. The twelve month study for the Alyeska Pipeline Service Company will gather data for regulatory compliance, risk assessment dispersion modeling. The network consists of seven sites. Four sites measure selected species of VOCs by laboratory grade gas chromatographs. The GCS yield hourly concentrations, special plumbing, valving and computer software enable unattended and automated operation. Chromatography is performed by flame ionization detector. Pollutants measured are benzene, ethyl-benzene, toluene and xylenes. Criteria pollutants are measured at four sites; one of which is for permit compliance. VOC and Criteria data presented will show site-by-site concentration comparisons, relate values to ambient standards, and applicability of previous modeling results. A discussion of the use of lab-grade gas chromatographs in the field for automated continuous sampling will be included. Meteorological data discussion will analyze circulation patterns within the fjord for patterns such as cross fjord transport and terrain induced flow regimes

Column studies on BTEX biodegradation under microaerophilic and denitrifying conditions

International Nuclear Information System (INIS)

Hutchins, S.R.; Moolenaar, S.W.; Rhodes, D.E.

1992-01-01

Two column tests were conducted using aquifer material to simulate the nitrate field demonstration project carried out earlier at Traverse City, Michigan. The objectives were to better define the effect nitrate addition had on biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEX) in the field study, and to determine whether BTEX removal can be enhanced by supplying a limited amount of oxygen as a supplemental electron acceptor. Columns were operated using limited oxygen, limited oxygen plus nitrate, and nitrate alone. In the first column study, benzene was generally recalcitrant compared to the alkylbenzenes (TEX), although some removal did occur. In the second column study, nitrate was deleted from the feed to the column originally receiving nitrate alone and added to the feed of the column originally receiving limited oxygen alone. Although the requirement for nitrate for optimum TEX removal was clearly demonstrated in these columns, there were significant contributions by biotic and abiotic processes other than denitrification which could not be quantified

Analysis of chemical contamination within a canal in a Mexican border colonia.

Science.gov (United States)

Owens, Janel E; Niemeyer, Emily D

2006-04-01

This study examines urban pollution within Derechos Humanos, a colonia popular in Matamoros, Tamaulipas, Mexico. General water quality indicators (coliform bacteria, total dissolved solids, ecologically relevant cations and anions), heavy metals (copper, lead, nickel, zinc, iron and cadmium), and volatile organic compounds (benzene, toluene, ethylbenzene, styrene, and dichlorobenzene and xylene isomers) were quantified within a wastewater canal running adjacent to the community. Water samples were collected at multiple sites along the banks of the canal and evidence of anthropogenic emissions existed at each sampling location. Sample site 2, approximately 10 m upstream of the colonia, contained both the widest range of hazardous pollutants and the greatest number exceeding US Environmental Protection Agency surface water standards. At each sampling location, high concentrations of total coliform (> 10(4) colonies/100 mL sample), lead (ranging from 0.05 to 0.40 mg/L), nickel (levels from 0.21 to 1.45 mg/L), and benzene (up to 9.80 mg/L) were noted.

Hydrotropic effect and thermodynamic analysis on the solubility and mass transfer coefficient enhancement of ethylbenzene

International Nuclear Information System (INIS)

Morais, Antony Bertie; Jayakumar, Chinnakannu; Gandhi, Nagarajan Nagendra

2013-01-01

Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0-3.0mol·L"−"1) and different system temperatures (303-333 K) on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, K_s, a measure of the effectiveness of a hydrotrope, was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined

Hydrotropic effect and thermodynamic analysis on the solubility and mass transfer coefficient enhancement of ethylbenzene

Energy Technology Data Exchange (ETDEWEB)

Morais, Antony Bertie; Jayakumar, Chinnakannu; Gandhi, Nagarajan Nagendra [Anna University, Chennai (India)

2013-04-15

Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0-3.0mol·L{sup −1}) and different system temperatures (303-333 K) on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, K{sub s}, a measure of the effectiveness of a hydrotrope, was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined.

Microbial conversion of ethylbenzene to 1-phenethanol and acetophenone by Nocardia tartaricans ATCC 31190.

Science.gov (United States)

Cox, D P; Goldsmith, C D

1979-09-01

A culture of Nocardia tartaricans ATCC 31190 was capable of catalyzing the conversion of ethylbenzene to 1-phenethanol and acetophenone while growing in a shake flask culture with hexadecane as the source of carbon and energy. This subterminal oxidative reaction with ethylbenzene appears not to have been previously reported for Nocardia species. When N. tartaricans was grown on glucose as its source of carbon and energy and ethylbenzene was added, no subsequent production of 1-phenethanol or acetophenone was observed. The mechanisms of 1-phenethanol and acetophenone production from ethylbenzene are thought to involve a subterminal oxidation of the alpha-carbon of the alkyl group to 1-phenethanol followed by biological oxidation of the latter to acetophenone.

Inhalation exposure and health risk levels to BTEX and carbonyl compounds of traffic policeman working in the inner city of Bangkok, Thailand

Science.gov (United States)

Kanjanasiranont, Navaporn; Prueksasit, Tassanee; Morknoy, Daisy

2017-03-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) and carbonyl compounds (CCs) are recognized traffic-related air pollutants in urban environments and are the focus of this study. In Bangkok, the BTEX and CC concentrations in both ambient air and personal exposure samples were studied during two periods (April-May and August-September 2014) at four different sampling sites around the Pathumwan District (three intersections and one T-junction). Traffic policemen, representing the high-exposure group for these toxic air pollutants, were observed, and the health risk to these workers was evaluated. Toluene was the predominant aromatic compound in the ambient and personal exposure samples. The maximum average ambient concentration of BTEX was 2968.96 μg/m3. Formaldehyde and acetaldehyde were the most abundant CCs at all of the sampling sites, with the greatest mean concentrations of these substances being 21.50 μg/m3 and 64.82 μg/m3, respectively. In the personal exposure samples, the highest levels of BTEX, formaldehyde and acetaldehyde concentrations were 2231.85 μg/m3, 10.61 μg/m3, and 16.03 μg/m3, respectively. In terms of risk assessment, benzene posed the greatest cancer risk (at the 95% CI), followed by toluene, acetaldehyde and formaldehyde (1.15E-02, 5.14E-03, 2.84E-04, and 2.52E-04, respectively). Three risk factors were investigated to reduce the total cancer risk levels: reducing the chemical concentration, exposure time and exposure duration. The use of a mask (chemical concentration) was the best way to reduce the risk to traffic police. However, the risk value of benzene (average 1.57E-05) was still higher than an acceptable value when using a mask.

Influence of frequently used industrial solvents and monomers of plastics on xenobiotic metabolism

Energy Technology Data Exchange (ETDEWEB)

Gut, I. (Institut Hygieny a Epidemiologie, Prague (Czechoslovakia))

1983-11-01

In male Wistar rats, inhalation of benzene, toluene, or styrene induced a dose-dependent increase of the in vitro hepatic microsomal metabolism of benzene, but toluene metabolism and microsomal cytochrome P-450 level were little affected. In phenobarbital pretreated rats the solvents induced increased biotransformation of benzene metabolism toluene, but relatively less than in controls, and benzene and toluene inhalation actually caused an apparent destruction of cytochrome P-450. In vivo rates of metabolism of toluene and styrene were in good agreement with the in vitro hepatic microsomal biotransformation of benzene or toluene, but benzene metabolism not due to inhibition of benzene metabolism in vivo caused by benzene metabolites. In simultaneously administered two solvents, toluene, styrene or xylene markedly inhibited metabolism of benzene-/sup 14/C, but toluene-/sup 14/C metabolsim was little affected by coadministered benzene, styrene or xylene. Various industrial solvents inhibited metabolism of acrylonitrile along the oxidative pathway leading to thiocyanate, but actually increased the rate of the conjugative pathway beginning with cyanoethylation of glutathion and the final products. Various derivatives of benzene had low inhibiting effect on antipyrine metabolism and clinical significance of such effect is of little significance. Inhibition of benzene metabolism by toluene followed in significantly decreased myelotoxicity of benzene, but the modification of acrylonitrile metabolism and pharmacokinetics by organic solvents given at low doses markedly increased lethal effects of acrylonitrile. The prediction of in vivo rates of metabolism based on the in vitro rates of hepatic microsomal metabolism is therefore possible, provided the inhibiting potency of the xenobiotic and/or its metabolites, self-induction of their metabolism, as well as differences in their pharmacokinetics are considered.

The Initial Comparison Study of Sodium Lignosulfonate, Sodium Dodecyl Benzene Sulfonate, and Sodium p-Toluene Sulfonate Surfactant for Enhanced Oil Recovery

Science.gov (United States)

Khoirul Anas, Argo; Iman Prakoso, Nurcahyo; Sasvita, Dilla

2018-04-01

Surfactant (surface active agent) exhibit numerous interesting properties that enable their use as additional component in mobilising of residual oil from capillary pore after secondary recovery process using gas injection and water flooding. In this study, Sodium Lignosulfonate (SLS) surfactant was successfully synthesized by applying batch method using lignin from oil palm empty fruit bunches as precursor. Furthermore, its performance in reducing interfacial tension of crude oil and formation water colloidal system was compared with commercial available surfactant including Sodium Dodecyl Benzene Sulfonate (SDBS) and Sodium p-Toluene Sulfonate (SpTS). The synthesized SLS surfactant was characterized by using Fourier Transform Infrared (FTIR) spectroscopy. Meanwhile, its performance in reducing interfacial tension of crude oil and formation water colloidal system was analyzed by using compatibility test, phase behaviour analysis, and interfacial tension (IFT) measurement. The compatibility test shows that SLS, SDBS, and SpTS surfactants were compatible with formation water. In addition, the phase behaviour analysis shows that SLS surfactant was better than SpTS surfactant, while SDBS surfactant generates the highest performance proved by the best microemulsion formation resulted by SDBS. Furthermore, the optimum concentration of SLS, SDBS, and SpTS surfactants in reducing the interfacial tension of crude oil and formation water was 1.0%. The IFT measurement indicates that the performance of SLS with the value of 1.67 mN/m was also better than SpTS surfactant with the value of 3.59 mN/m. Meanwhile, SDBS surfactant shows the best performance with the IFT value of 0.47 mN/m.

Comments for the Update to the ATSDR Toxicological Profile for JP-5 and JP-8 Occurring in FY14

Science.gov (United States)

2013-12-30

Exposure Chamber. Made of stainless steel, about the size and shape of an attaché case, this IN-TOX product will hold up to 24 mice, each contained in...hydrocarbon markers (n- octane, n-decane, n-tetradecane, toluene, ethylbenzene , and m-xylene)” is incomplete and therefore incorrect. The model, in...aromatic hydrocarbon markers (n-octane, n-decane, n- tetradecane, toluene, ethylbenzene , and m-xylene), plus three chemical lumped compartments based

Potential occurrence of MTBE and BTEX in groundwater resources of Amman-Zarqa basin, Jordan

International Nuclear Information System (INIS)

Al Kuisi, Mustafa; Saffarini, Ghazi; Yaseen, Najal; Alawi, Mahmoud

2012-01-01

This study investigates potential occurrence, distribution, and sources of the newly added gasoline oxygenate, methyl-tert-butyl ether (MTBE) and the petroleum derivatives benzene, toluene, ethylbenzene, and xylenes called collectively, BTEX, in Jordan's heavily populated Amman-Zarqa Basin (AZB). It presents the first data on the levels of MTBE and BTEX in the aquifers of this basin. One hundred and seventy-nine (179) groundwater wells were sampled near petrol service stations, oil refinery storage tanks, car wrecks, bus stations, and chemical industries at different locations in the basin. Headspace GC and purge and trap GC-MS were utilized to determine the target substances in the samples. Concentrations of BTEX varied between no-detection (minimum) for all of them to 6.6 μg/L (maximum) for ethylbenzene. MTBE was found in few samples but none has exceeded the regulated levels; its concentrations ranged between no-detection to 4.1 μg/L. However, though the contamination levels are very low they should be considered alarming. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Accumulation and turnover of metabolites of toluene and xylene in nasal mucosa and olfactory bulb in the mouse

International Nuclear Information System (INIS)

Ghantous, H.; Dencker, L.; Danielsson, B.R.G; Gabrielsson, J.; Bergman, K.

1990-01-01

Autoradiography of male mice following inhalation of the radioactively labelled solvents, toluene, xylene, and styrene, revealed an accumulation of non-volatile metabolites in the nasal mucosa and olfactory bulb of the brain. Since no accumulation occurred after benzene inhalation, it was assumed that the activity represented aromatic acids, which are known metabolites of these solvents. This was supported by the finding that also radioactive benzoic acid (main metabolite of toluene) and salicylic acid accumulated in the olfactory bulb. High-performance liquid chromatography revealed that after toluene inhalation (for 1 hr), nasal mucosa and olfactory bulb contained mainly benzoic acid, with a strong accumulation in relation to blood plasma, and considerably less of its blycine conjugate, hippuric acid. After xylene inhalation, on the other hand, methyl hippuric acid dominated over the non-conjugated metabolite, toluic acid. The results indicate a specific, possibly axonal flow-mediated transport of aromatic acids from the nasal mucosa to the olfactory lobe of the brain. The toxicological significance of these results remains to be studied. (author)

Hoe Creek groundwater restoration, 1989

Energy Technology Data Exchange (ETDEWEB)

Renk, R.R.; Crader, S.E.; Lindblom, S.R.; Covell, J.R.

1990-01-01

During the summer of 1989, approximately 6.5 million gallons of contaminated groundwater were pumped from 23 wells at the Hoe Creek underground coal gasification site, near Gillette, Wyoming. The organic contaminants were removed using activated carbon before the water was sprayed on 15.4 acres at the sites. Approximately 2647 g (5.8 lb) of phenols and 10,714 g (23.6 lb) of benzene were removed from the site aquifers. Phenols, benzene, toluene, ethylbenzene, and naphthalene concentrations were measured in 43 wells. Benzene is the only contaminant at the site exceeds the federal standard for drinking water (5 {mu}g/L). Benzene leaches into the groundwater and is slow to biologically degrade; therefore, the benzene concentration has remained high in the groundwater at the site. The pumping operation affected groundwater elevations across the entire 80-acre site. The water levels rebounded quickly when the pumping operation was stopped on October 1, 1989. Removing contaminated groundwater by pumping is not an effective way to clean up the site because the continuous release of benzene from coal tars is slow. Benzene will continue to leach of the tars for a long time unless its source is removed or the leaching rate retarded through mitigation techniques. The application of the treated groundwater to the surface stimulated plant growth. No adverse effects were noted or recorded from some 60 soil samples taken from twenty locations in the spray field area. 20 refs., 52 figs., 8 tabs.

Atmospheric Benzene Observations from an Oil and Gas Field in the Denver Julesburg Basin in July and August 2014

Science.gov (United States)

Halliday, Hannah S.; Thompson, Anne M.; Wisthaler, Armin; Blake, Donald; Hornbrook, Rebecca S.; Mikoviny, Tomas; Mueller, Markus; Eichler, Philipp; Apel, Eric C.; Hills, Alan

2016-01-01

High time resolution measurements of volatile organic compounds (VOCs) were collectedusing a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the PlattevilleAtmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (ONG) developmentimpacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurementswere carried out in July and August 2014 as part of NASAs Deriving Information on Surface Conditions fromColumn and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign. ThePTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontalsurveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (meanbenzene 0.53 ppbv, maximum benzene 29.3 ppbv), primarily at night (mean nighttime benzene 0.73ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurementsindicate that benzene originated from within the WGF, and typical source signatures detected in the canistersamples implicate emissions from ONG activities rather than urban vehicular emissions as primary benzenesource. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerlyflow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that trafficemissions were not responsible for the observed high benzene levels. Previous measurements at the BoulderAtmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzeneenhancements between the two atmospheric observatories. Fugitive emissions of benzene from ONGoperations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO.

THE MATHEMATICAL MODEL DEVELOPMENT OF THE ETHYLBENZENE DEHYDROGENATION PROCESS KINETICS IN A TWO-STAGE ADIABATIC CONTINUOUS REACTOR

Directory of Open Access Journals (Sweden)

V. K. Bityukov

2015-01-01

Full Text Available The article is devoted to the mathematical modeling of the kinetics of ethyl benzene dehydrogenation in a two-stage adiabatic reactor with a catalytic bed functioning on continuous technology. The analysis of chemical reactions taking place parallel to the main reaction of styrene formation has been carried out on the basis of which a number of assumptions were made proceeding from which a kinetic scheme describing the mechanism of the chemical reactions during the dehydrogenation process was developed. A mathematical model of the dehydrogenation process, describing the dynamics of chemical reactions taking place in each of the two stages of the reactor block at a constant temperature is developed. The estimation of the rate constants of direct and reverse reactions of each component, formation and exhaustion of the reacted mixture was made. The dynamics of the starting material concentration variations (ethyl benzene batch was obtained as well as styrene formation dynamics and all byproducts of dehydrogenation (benzene, toluene, ethylene, carbon, hydrogen, ect.. The calculated the variations of the component composition of the reaction mixture during its passage through the first and second stages of the reactor showed that the proposed mathematical description adequately reproduces the kinetics of the process under investigation. This demonstrates the advantage of the developed model, as well as loyalty to the values found for the rate constants of reactions, which enable the use of models for calculating the kinetics of ethyl benzene dehydrogenation under nonisothermal mode in order to determine the optimal temperature trajectory of the reactor operation. In the future, it will reduce energy and resource consumption, increase the volume of produced styrene and improve the economic indexes of the process.

Photodissociation of ethylbenzene and n-propylbenzene in a molecular beam

Science.gov (United States)

Huang, Cheng-Liang; Jiang, Jyh-Chiang; Lee, Yuan T.; Ni, Chi-Kung

2002-10-01

The photodissociation of jet-cooled ethylbenzene and n-propylbenzene at both 193 and 248 nm was studied using vacuum ultraviolet photoionization/multimass ion imaging techniques. The photofragment translational energy distributions from both the molecules obtained at 193 nm show that the probability of portioning energy to product translational energy decreases monotonically with increasing translational energy. They indicate that the dissociation occurs from the ground electronic state. However, the photofragment translational energy distributions from both molecules obtained at 248 nm contain a fast and a slow component. 75% of ethylbenzene and 80% of n-propylbenzene following the 248 nm photoexcitation dissociate from electronic excited state, resulting in the fast component. The remaining 25% of ethylbenzene and 20% of n-propylbenzene dissociate through the ground electronic state, giving rise to the slow component. A comparison with an ab initio calculation suggests that the dissociation from the first triplet state corresponds to the fast component in translational energy distribution.

Volumetric, Viscometric and Excess Properties of Binary Mixtures of 1-Iodobutane with Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Mesitylene at Temperatures from 303.15 to 313.15 K

Directory of Open Access Journals (Sweden)

Sangita Sharma

2013-01-01

Full Text Available Densities and viscosities have been determined for binary mixtures of 1-iodobutane with benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene at 303.15, 308.15, and 313.15 K for the entire composition range at atmospheric pressure. The excess molar volumes, , deviations in viscosity, Δη, and excess Gibbs’ free energy of activation flow, Δ have been calculated from the experimental values. The experimental data were fitted to Redlich-Kister polynomial equation. The variations of these parameters with composition of the mixtures and temperature have been discussed in terms of molecular interactions occurring in these mixtures. Further, the viscosities of these binary mixtures were calculated theoretically from their corresponding pure component data by using empirical relations like Bingham, Arrhenius and Eyring, Kendall and Munroe, Hind, Katti and Chaudhari, Grunberg and Nissan, and Tamura and Kurata. Comparison of various interaction parameters has been expressed to explain the intermolecular interactions between iodobutane and selected hydrocarbons.

Volatile organic compounds and particulate matter in child care facilities in the District of Columbia: Results from a pilot study.

Science.gov (United States)

Quirós-Alcalá, L; Wilson, S; Witherspoon, N; Murray, R; Perodin, J; Trousdale, K; Raspanti, G; Sapkota, A

2016-04-01

Many young children in the U.S. spend a significant portion of their day in child care facilities where they may be exposed to contaminants linked to adverse health effects. Exposure data on volatile organic compounds (VOCs) and particulate matter (PM) in these settings is scarce. To guide the design of a larger exposure assessment study in urban child care facilities, we conducted a pilot study in which we characterized indoor concentrations of select VOCs and PM. We recruited 14 child care facilities in the District of Columbia (Washington, DC) and measured indoor concentrations of seven VOCs (n=35 total samples; 2-5 samples per facility): benzene, carbon tetrachloride, chloroform, ethylbenzene, o-xylene, p-xylene, and toluene in all facilities; and collected real-time PM measurements in seven facilities. We calculated descriptive statistics for contaminant concentrations and computed intraclass correlation coefficients (ICC) to evaluate the variability of VOC levels indoors. We also administered a survey to collect general health information on the children attending these facilities, and information on general housekeeping practices and proximity of facilities to potential sources of target contaminants. We detected six of the seven VOCs in the majority of child care facilities with detection frequencies ranging from 71% to 100%. Chloroform and toluene were detected in all samples. Median (range) concentrations for toluene, chloroform, benzene, o-xylene, ethylbenzene, and carbon tetrachloride were: 5.6µg/m(3) (0.6-16.5µg/m(3)), 2.8µg/m(3) (0.4-53.0µg/m(3)), 1.4µg/m(3) (below the limit of detection or air fresheners and/or scented candles were used in half of the facilities, and at least one child in each facility had physician-diagnosed asthma (median asthma prevalence rate=10.2%). We found quantifiable levels of VOCs and PM in the child care facilities sampled. Given that exposures to environmental contaminants during critical developmental stages may

Early Liver and Kidney Dysfunction Associated with Occupational Exposure to Sub-Threshold Limit Value Levels of Benzene, Toluene, and Xylenes in Unleaded Petrol.

Science.gov (United States)

Neghab, Masoud; Hosseinzadeh, Kiamars; Hassanzadeh, Jafar

2015-12-01

Unleaded petrol contains significant amounts of monocyclic aromatic hydrocarbons such as benzene, toluene, and xylenes (BTX). Toxic responses following occupational exposure to unleaded petrol have been evaluated only in limited studies. The main purpose of this study was to ascertain whether (or not) exposure to unleaded petrol, under normal working conditions, is associated with any hepatotoxic or nephrotoxic response. This was a cross-sectional study in which 200 employees of Shiraz petrol stations with current exposure to unleaded petrol, as well as 200 unexposed employees, were investigated. Atmospheric concentrations of BTX were measured using standard methods. Additionally, urine and fasting blood samples were taken from individuals for urinalysis and routine biochemical tests of kidney and liver function. The geometric means of airborne concentrations of BTX were found to be 0.8 mg m(-3), 1.4 mg m(-3), and 2.8 mg m(-3), respectively. Additionally, means of direct bilirubin, alanine aminotransferase, aspartate aminotransferase, blood urea and plasma creatinine were significantly higher in exposed individuals than in unexposed employees. Conversely, serum albumin, total protein, and serum concentrations of calcium and sodium were significantly lower in petrol station workers than in their unexposed counterparts. The average exposure of petrol station workers to BTX did not exceed the current threshold limit values (TLVs) for these chemicals. However, evidence of subtle, subclinical and prepathologic early liver and kidney dysfunction was evident in exposed individuals.

BTEX and MTBE adsorption onto raw and thermally modified diatomite.

Science.gov (United States)

Aivalioti, Maria; Vamvasakis, Ioannis; Gidarakos, Evangelos

2010-06-15

The removal of BTEX (benzene, toluene, ethyl-benzene and xylenes) and MTBE (methyl tertiary butyl ether) from aqueous solution by raw (D(R)) and thermally modified diatomite at 550, 750 and 950 degrees C (D(550), D(750) and D(950) respectively) was studied. Physical characteristics of both raw and modified diatomite such as specific surface, pore volume distribution, porosity and pH(solution) were determined, indicating important structural changes in the modified diatomite, due to exposure to high temperatures. Both adsorption kinetic and isotherm experiments were carried out. The kinetics data proved a closer fit to the pseudo-second order model. Maximum values for the rate constant, k(2), were obtained for MTBE and benzene (48.9326 and 18.0996 g mg(-1)h(-1), respectively) in sample D(550). The isotherm data proved to fit the Freundlich model more closely, which produced values of the isotherm constant 1/n higher than one, indicating unfavorable adsorption. The highest adsorption capacity, calculated through the values of the isotherm constant k(F), was obtained for MTBE (48.42 mg kg(-1) (mg/L)(n)) in sample D(950). Copyright 2010 Elsevier B.V. All rights reserved.

Emission and source characterization of monoaromatic hydrocarbons from coke production

Energy Technology Data Exchange (ETDEWEB)

He, Q.S.; Wang, X.M.; Sheng, G.Y.; Fu, J.M. [Chinese Academy of Sciences, Guangzhou (China). State Key Laboratory of Organic Geochemistry

2005-09-15

Monoaromatic hydrocarbons (MAHs) from indigenous and industrial coking processes are studied in Shanxi province. They are sampled on the top of coke ovens and in the chimneys using stainless steel canister and determined by GC/MSD after preconcentration with liquid nitrogen. Benzene, toluene and xylene are the main components among MAHs emitted from coking processes. Benzene and the total MAHs concentrations were as high as 3421.0 microg/m3 and 4 865.9 microg/m3 in the air from indigenous coking, 548.7 microg/m3 and 1 054.8 microg/m3 in the oventop air from industrial coking, and 1 376.4 microg/m3 and 1 819.4 microg/m3 in stack gas from industrial coking, respectively. The MAHs concentrations vary greatly during the indigenous coking process, which in the prophase (from firing to 10 days) is obviously higher than in the anaphase (10 days to quenching the coke). In industrial coking the MAHs in the oventop air are highest when charging the coal and next when transferring the hot coke, but in stack gas they are highest when charging coal and lowest when transferring the coke. Benzene, toluene, ethylbenzene and xylene (BTEX) in industrial coking samples show good linearity, indicating that MAHs in industrial coking might come predominantly from coal pyrolysis; but BTEX distribute dispersedly in indigenous coking samples, indicating that its emission might be affected by many factors. In all samples BTEX ratios especially high B/E ratio, is unique among MAHs sources, and might be helpful to characterize pollution from coking.

[Emission and source characterization of monoaromatic hydrocarbons from coke production].

Science.gov (United States)

He, Qiu-Sheng; Wang, Xin-Ming; Sheng, Guo-Ying; Fu, Jia-Mo

2005-09-01

Monoaromatic hydrocarbons (MAHs) from indigenous and industrial coking processes are studied in Shanxi province. They are sampled on the top of coke ovens and in the chimneys using stainless steel canister and determined by GC/MSD after preconcentration with liquid nitrogen. Benzene, toluene and xylene are the main components among MAHs emitted from coking processes. Benzene and the total MAHs concentrations were as high as 3421.0 microg/m3 and 4 865.9 microg/m3 in the air from indigenous coking, 548.7 microg/m3 and 1 054.8 microg/m3 in the oventop air from industrial coking, and 1 376.4 microg/m3 and 1 819.4 microg/m3 in stack gas from industrial coking, respectively. The MAHs concentrations vary greatly during the indigenous coking process, which in the prophase (from firing to 10 days) is obviously higher than in the anaphase (10 days to quenching the coke). In industrial coking the MAHs in the oventop air are highest when charging the coal and next when transferring the hot coke, but in stack gas they are highest when charging coal and lowest when transferring the coke. Benzene, toluene, ethylbenzene and xylene (BTEX) in industrial coking samples show good linearity, indicating that MAHs in industrial coking might come predominantly from coal pyrolysis; but BTEX distribute dispersedly in indigenous coking samples, indicating that its emission might be affected by many factors. In all samples BTEX ratios especially high B/E ratio, is unique among MAHs sources, and might be helpful to characterize pollution from coking.

Assessment of indoor air concentrations of VOCs and their associated health risks in the library of Jawaharlal Nehru University, New Delhi.

Science.gov (United States)

Kumar, Amit; Singh, Bhupendra Pratap; Punia, Monika; Singh, Deepak; Kumar, Krishan; Jain, V K

2014-02-01

The present work investigated the levels of total volatile organic compounds (TVOC) and benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX) in different microenvironments in the library of Jawaharlal Nehru University in summer and winter during 2011-2012. Carcinogenic and non-carcinogenic health risks due to organic compounds were also evaluated using US Environmental Protection Agency (USEPA) conventional approaches. Real-time monitoring was done for TVOC using a data-logging photo-ionization detector. For BTEX measurements, the National Institute for Occupational Safety and Health (NIOSH) standard method which consists of active sampling of air through activated charcoal, followed by analysis with gas chromatography, was performed. Simultaneously, outdoor measurements for TVOC and BTEX were carried out. Indoor concentrations of TVOC and BTEX (except benzene) were higher as compared to the outdoor for both seasons. Toluene and m/p-xylene were the most abundant organic contaminant observed in this study. Indoor to outdoor (I/O) ratios of BTEX compounds were generally greater than unity and ranged from 0.2 to 8.7 and 0.2 to 4.3 in winter and summer, respectively. Statistical analysis and I/O ratios showed that the dominant pollution sources mainly came from indoors. The observed mean concentrations of TVOC lie within the second group of the Molhave criteria of indoor air quality, indicating a multifactorial exposure range. The estimated lifetime cancer risk (LCR) due to benzene in this study exceeded the value of 1 × 10(-6) recommended by USEPA, and the hazard quotient (HQ) of non-cancer risk came under an acceptable range.

Health risk assessment of ambient air concentrations of benzene, toluene and xylene (BTX) in service station environments.

Science.gov (United States)

Edokpolo, Benjamin; Yu, Qiming Jimmy; Connell, Des

2014-06-18

A comprehensive evaluation of the adverse health effects of human exposures to BTX from service station emissions was carried out using BTX exposure data from the scientific literature. The data was grouped into different scenarios based on activity, location and occupation and plotted as Cumulative Probability Distributions (CPD) plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ) at 50% (CEXP50) and 95% (CEXP95) exposure levels. HQ50 and HQ95 > 1 were obtained with benzene in the scenario for service station attendants and mechanics repairing petrol dispensing pumps indicating a possible health risk. The risk was minimized for service stations using vapour recovery systems which greatly reduced the benzene exposure levels. HQ50 and HQ95 service station attendants than any other scenario.

ZnO nanorod array polydimethylsiloxane composite solid phase micro-extraction fiber coating: fabrication and extraction capability.

Science.gov (United States)

Wang, Dan; Wang, Qingtang; Zhang, Zhuomin; Chen, Guonan

2012-01-21

ZnO nanorod array coating is a novel kind of solid-phase microextraction (SPME) fiber coating which shows good extraction capability due to the nanostructure. To prepare the composite coating is a good way to improve the extraction capability. In this paper, the ZnO nanorod array polydimethylsiloxane (PDMS) composite SPME fiber coating has been prepared and its extraction capability for volatile organic compounds (VOCs) has been studied by headspace sampling the typical volatile mixed standard solution of benzene, toluene, ethylbenzene and xylene (BTEX). Improved detection limit and good linear ranges have been achieved for this composite SPME fiber coating. Also, it is found that the composite SPME fiber coating shows good extraction selectivity to the VOCs with alkane radicals.

Integration of decentralized torrefaction with centralized catalytic pyrolysis to produce green aromatics from coffee grounds.

Science.gov (United States)

Chai, Li; Saffron, Christopher M; Yang, Yi; Zhang, Zhongyu; Munro, Robert W; Kriegel, Robert M

2016-02-01

The aim of this work was to integrate decentralized torrefaction with centralized catalytic pyrolysis to convert coffee grounds into the green aromatic precursors of terephthalic acid, namely benzene, toluene, ethylbenzene, and xylenes (BTEX). An economic analysis of this bioproduct system was conducted to examine BTEX yields, biomass costs and their sensitivities. Model predictions were verified experimentally using pyrolysis GC/MS to quantify BTEX yields for raw and torrefied biomass. The production cost was minimized when the torrefier temperature and residence time were 239°C and 34min, respectively. This optimization study found conditions that justify torrefaction as a pretreatment for making BTEX, provided that starting feedstock costs are below $58 per tonne. Copyright © 2015. Published by Elsevier Ltd.

Remediation of hydrocarbons in crude oil-contaminated soils using Fenton's reagent.

Science.gov (United States)

Ojinnaka, Chukwunonye; Osuji, Leo; Achugasim, Ozioma

2012-11-01

Sandy soil samples spiked with Bonny light crude oil were subsequently treated with Fenton's reagent at acidic, neutral, and basic pH ranges. Oil extracts from these samples including an untreated one were analyzed 1 week later with a gas chromatograph to provide evidence of hydrocarbon depletion by the oxidant. The reduction of three broad hydrocarbon groups-total petroleum hydrocarbon (TPH); benzene, toluene, ethylbenzene, and xylene (BTEX); and polycyclic aromatic hydrocarbon (PAH) were investigated at various pHs. Hydrocarbon removal was efficient, with treatment at the acidic pH giving the highest removal of about 96% for PAH, 99% for BTEX, and some TPH components experiencing complete disappearance. The four-ringed PAHs were depleted more than their three-ringed counterparts at the studied pH ranges.

Enhanced biodegradation of hydrocarbons in-situ via bioventing

International Nuclear Information System (INIS)

Newman, B.; Martinson, M.; Smith, G.; McCain, L.

1993-01-01

This case study discusses the remediation of soils beneath a former service station impacted with volatile and semi-volatile petroleum compounds. Subsurface investigation revealed hydrocarbon contamination representative of weathered gasoline and diesel fuel in a stratified soil profile consisting of sand and silts. Only unsaturated soils were contaminated with no impact to ground water. A bioventing corrective action approach was selected which included excavation of 6,100 cubic yards of impacted soils with soil mixing to add inorganic nutrients and eliminate soil heterogeneities. Soils were then returned to the excavation after forced-air ventilation lateral lines were installed at the floor of the excavation. Soil vapor concentrations of benzene, toluene, ethylbenzene, xylenes (BTEX) rapidly declined within the first three months of system operation to nondetectable levels

[Pollution characteristics and health risk assessment of atmospheric VOCs in the downtown area of Guangzhou, China].

Science.gov (United States)

Li, Lei; Li, Hong; Wang, Xue-Zhong; Zhang, Xin-Min; Wen, Chong

2013-12-01

The measurements of 31 kinds of VOCs in the ambient air of a site were carried out in the downtown of Guangzhou by online method from November 5, 2009 to November 9, 2009. The ambient level and composition characteristics, temporal variation characteristics, sources identification, and chemical reactivity of VOCs were studied, and the health risk of VOCs in the ambient air in the study area was assessed by using the international recognized health risk assessment method. Results showed that the mean and the range of the mass concentrations of 31 VOCs were 114.51 microg x m(-3) and 29.42-546.06 microg x m(-3), respectively. The mass concentrations of 31 VOCs, and those of alkanes, alkenes, and aromatics all showed a changing trend of higher in the morning and in the evening, and lower at noontime. Vehicular exhaust, gasoline and liquefied petroleum gas evaporates were the main sources of VOCs with the volatilization of paints and solvents being important emission sources. Toluene, trans-2-butene, m/p-xylene, i-butane, and 1,3,5-trimethylbenzene were the key reactive species among the 31 VOCs. Vehicular exhaust and gasoline evaporation were the main sources of VOCs leading to the formation of ozone. Health risk assessment showed that n-hexane, 1,3-butadiene, benzene, toluene, ethylbenzene, m/p-xylene and o-xylene had no appreciable risk of adverse non-cancer health effect on the exposed population, but 1, 3-butadiene and benzene had potential cancer risk. By comparing the corresponding data about health risk assessment of benzene compounds in some cities in China, it is concluded that benzene can impose relatively high cancer risk to the exposed populations in the ambient air of some cities in China. Therefore, strict countermeasures should be taken to further control the pollution of benzene in the ambient air of cities, and it is imperative to start the related studies and develop the atmospheric environmental health criteria and national ambient air quality

Performance of rare earth modified faujasites in the process of toluene disproportionation

International Nuclear Information System (INIS)

Azzouz, A.; Fourar, M.; Berrak, A.

1984-06-01

The purpose of the present paper is the study of the performances of some catalysts based on y-type faujasite exchanged with La (3+) and Ce (3+) cations in the process of toluene disproportionation to benzene and xylenes. In the first stage the crystallographic study by the X-rays diffraction method shows that the cation exchange causes 311 plane displacements in the zeolite structure, accompanied by a decrease of diffraction limit intensity. Further the faujasite pretreatment with NH4 (4+) ions plays some role in the protection of the crystallinity. Moreover the cation exchange seems to take an optimum value around 73% for which the toluene conversion is maximum. This phenomenon is probably due to a decrease of the internal free volume for a pronounced cation exchange. The best performances are obtained by the zeolite that has undergone a slow and programmed thermal activation after cation exchange. This is probably due to the slowness of ion rearrangement phenomena, and of the catalytic surface restructuration. In the second stage the realization of toluene disproportionation process shows that the cation exchange with such elements confers to the faujasite an appreciable catalytic activity in the temperature range of 350-500 degC. The catalysts obtained permit about 20-60% toluene conversions. The catalytic activity is slightly higher in La-modified samples, whereas those containing Ce (3+) present relatively a better selectivity to the main process. Nevertheless, both types of catalysts show approximately a similar behaviour, favourizing the p-xylene formation. The proportion of the latter exceeds that of thermodynamic equilibrium at temperatures less than 430 degC. The temperature increase affects this selectivity. This is probably due to dehydration phenomenon which are frequent around this value

Toxicokinetic Study for Investigation of Sex Differences in Internal Dosimetry of Jet Propulsion Fuel 8 (JP-8) in the Laboratory Rat

Science.gov (United States)

2013-07-26

brain and observed cochlea concentrations of n-octane, n-decane, n-tetradecane, ethylbenzene , m-xylene and toluene in rats exposed to JP-8 (high...occur in combination with noise expo- sures (Department of the Army, 1998). The hydrocarbons ethylbenzene , toluene, and p-xylene, known to be present in...to supply JP-8 to the Cannon nose-only exposure system. Rats were exposed to JP-8 on a 52-position Cannon nose-only exposure system (Lab Products

Aromatic hydrocarbons at urban, sub-urban, rural (8°52'N; 67°19'W) and remote sites in Venezuela

Science.gov (United States)

Holzinger, R.; Kleiss, B.; Donoso, L.; Sanhueza, E.

Using the novel on-line proton transfer reaction mass spectrometry (PTR-MS) technique, atmospheric concentrations of benzene, toluene, xylenes, and C 9-benzenes were measured in Caracas (urban), Altos de Pipe (sub-urban), Calabozo (rural) and Parupa (remote), during various campaigns in 1999 and 2000. Average daytime mixing ratios measured in Caracas are 1.1, 3.2, 3.7, and 2.7 nmol/mol for benzene, toluene, xylenes, and C 9-benzenes. At the sub-urban site, located only few km from Caracas, relatively low levels (˜20% of the levels measured in Caracas) of these aromatic hydrocarbons were observed. At the rural site during the dry season, higher concentrations of benzene (0.15 nmol/mol) were recorded, whereas those of toluene (0.08 nmol/mol) were lower during that time. The aromatic hydrocarbon ratios in the wet season (benzene: 0.08 nmol/mol; toluene: 0.09 nmol/mol) are consistent with an aged urban plume, whereas biomass burning emissions dominate during the dry season. From rural and urban [benzene]/[toluene] ratios a mean HO concentration of 2.6×10 6 molecules/cm 3 was estimated during the wet season. This value must be considered an overestimate because it does not account for background concentrations which are likely for benzene and toluene. At the remote "La Gran Sabana" region (Parupa) very low mixing ratios (0.031 and 0.015 nmol/mol for benzene and toluene) are showing the pristine region to be unaffected by local sources. From the [benzene]/[toluene] ratio we deduced, that "urban" air arriving from the coastline (350 km) is likely mixed with air containing some background of benzene and toluene. Urban emissions (automobiles) should be the major source of aromatic compounds, however, during the dry season biomass burning seems to make an important contribution.

An in-situ FTIR study of the side-chain alkylation of toluene with methanol

International Nuclear Information System (INIS)

King, S.T.; Garces, J.

1985-01-01

The side-chain alkylation of toluene with methanol to styrene and ethylbenzene can be an economically attractive industrial process if it has high enough conversion and selectivity. This process has been investigated by many others using zeolites or metal oxides as the catalyst. It has been generally accepted that high basicity in certain size pores in the catalyst is required for such side-chain alkylation. However, the actual reaction mechanism is still not understood. In this paper the results of an in-situ FT-IR study of the side-chain alkylation in Li, Na, K, Rb and Cs exchanged X zeolites is discussed. It was found that the KX, RbX and CsX zeolites, which are capable of side-chain alkylation, also form surface formate and a surface precursor of formate from methanol decomposition. While the surface formate itself is not the alkylation agent, the observed formate precursor may be the intermediate for side-chain alkylation

Preliminary study to prepare a reference material of toluene metabolite - o-cresol and benzene metabolite-phenol - in human

Czech Academy of Sciences Publication Activity Database

Šperlingová, I.; Dabrowská, L.; Stránský, V.; Kučera, Jan; Tichý, M.

2006-01-01

Roč. 11, č. 5 (2006), s. 231-235 ISSN 0949-1775 R&D Projects: GA MZd NR7831 Institutional research plan: CEZ:AV0Z10480505 Keywords : reference material * toluene metabolites * o-cresol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.640, year: 2006

Oxidative Dehydrogenation (ODH) of Ethylbenzene with and over ...

Indian Academy of Sciences (India)

SALEM CHEKNOUN

2018-03-27

Mar 27, 2018 ... attention from both fundamental and industrial point of view because of their ... propane and isobutene selective oxidation to acrylic or isobutyric acids ... Ethylbenzene is one of the most important arylalka- nes, being a starting ...

Effect of trichloroethylene (TCE) and toluene concentrations on TCE and toluene biodegradation and the population density of TCE and toluene degraders in soil.

OpenAIRE

Mu, D Y; Scow, K M

1994-01-01

Toluene is one of several cosubstrates able to support the cometabolism of trichloroethylene (TCE) by soil microbial communities. Indigenous microbial populations in soil degraded TCE in the presence, but not the absence, of toluene after a 60- to 80-h lag period. Initial populations of toluene and TCE degraders ranged from 0.2 x 10(3) to 4 x 10(3) cells per g of soil and increased by more than 4 orders of magnitude after the addition of 20 micrograms of toluene and 1 microgram of TCE per ml ...

Assessment of Surface Water Contamination from Coalbed Methane Fracturing-Derived Volatile Contaminants in Sullivan County, Indiana, USA.

Science.gov (United States)

Meszaros, Nicholas; Subedi, Bikram; Stamets, Tristan; Shifa, Naima

2017-09-01

There is a growing concern over the contamination of surface water and the associated environmental and public health consequences from the recent proliferation of hydraulic fracturing in the USA. Petroleum hydrocarbon-derived contaminants of concern [benzene, toluene, ethylbenzene, and xylenes (BTEX)] and various dissolved cations and anions were spatially determined in surface waters around 15 coalbed methane fracking wells in Sullivan County, IN, USA. At least one BTEX compound was detected in 69% of sampling sites (n = 13) and 23% of sampling sites were found to be contaminated with all of the BTEX compounds. Toluene was the most common BTEX compound detected across all sampling sites, both upstream and downstream from coalbed methane fracking wells. The average concentration of toluene at a reservoir and its outlet nearby the fracking wells was ~2× higher than other downstream sites. However, one of the upstream sites was found to be contaminated with BTEX at similar concentrations as in a reservoir site nearby the fracking well. Calcium (~60 ppm) and sulfates (~175 ppm) were the dominant cations and anions, respectively, in surface water around the fracking sites. This study represents the first report of BTEX contamination in surface water from coalbed methane hydraulic fracturing wells.

Research on release rate of volatile organic compounds in typical vessel cabin

Directory of Open Access Journals (Sweden)

ZHANG Jinlan

2018-02-01

Full Text Available [Objectives] Volatile Organic Compounds (VOC should be efficiently controlled in vessel cabins to ensure the crew's health and navigation safety. As an important parameter, research on release rate of VOCs in cabins is required. [Methods] This paper develops a method to investigate this parameter of a ship's cabin based on methods used in other closed indoor environments. A typical vessel cabin is sampled with Tenax TA tubes and analyzed by Automated Thermal Desorption-Gas Chromatography-Mass Spectrometry (ATD-GC/MS. The lumped mode is used and the release rate of Benzene, Toluene, Ethylbenzene and Xylene (BTEX, the typical representatives of VOCs, is obtained both in closed and ventilated conditions. [Results] The results show that the content of xylene and Total Volatile Organic Compounds (TVOC exceed the indoor environment standards in ventilated conditions. The BTEX release rate is similar in both conditions except for the benzene. [Conclusions] This research builds a method to measure the release rate of VOCs, providing references for pollution character evaluation and ventilation and purification system design.

Rapid sampling of BTEX in air by SPME in the city of Nice and at the Nice-Cote d'Azur airport

International Nuclear Information System (INIS)

Tumbiolo, S.; Gal, J.F.; Maria, P.Ch.; Laborde, P.; Teton, S.

2006-01-01

This article presents the results of a tentative application of Solid Phase Micro Extraction (SPME) to the analysis of BTEX (benzene, toluene, ethyl-benzene and xylenes) at the μg/m 3 level in indoor and outdoor air. The salient features of the method validation are reported. Sampling by QUALITAIR using Radiello passive samplers, was carried out from 2001 to 2004 in the city of Nice and its airport. Urban traffic impact was proved, but a link between BTX concentrations and the variations of airport activities was not clearly established. During the same period, several samplings were performed using SPME. Taking into account the short (30 minutes) sampling time, rapid changes of BTEX concentrations were evidenced, as for example the start of airplane engines. As field studies have shown, SPME technique appears as a method of choice for fast qualitative analysis and quantitative determination of Volatile Organic Compounds (VOC). The small dimensions of the SPME sampling system and the short sampling time let envisage its utilisation for the rapid diagnostic and the monitoring of indoor air quality. (author)

Avaliação da influência do etanol sobre o grau de volatilização BTEX em solos impactados por derrames de gasolina/etanol Evaluation of the ethanol influence over the volatilization grade of BTEX in soil impacted by gasoline/ethanol spills

Directory of Open Access Journals (Sweden)

Alexandra Rodrigues Finotti

2009-12-01

Full Text Available O principal objetivo deste trabalho foi a avaliação quantitativa da influência do etanol sobre a volatilização de BTEX (benzeno, tolueno, etilbenzeno e xilenos em mistura de gasolina e etanol anidro 25% (v/v em colunas experimentais, que simularam solos contaminados com gasolina pura e gasolina/etanol. Todos os BTEX apresentaram expressivo aumento das taxas de volatilização na coluna contendo a mistura gasolina/etanol. Porém, em termos percentuais, o maior e menor aumento nas taxas de volatilização foi observado para tolueno e benzeno, respectivamente. Em amostras de controle, com o percentual de etanol variando entre 0 e 25%, não foi observado aumento no grau de volatilização do etilbenzeno, enquanto que o grau de volatilização dos xilenos foi reduzido. Estes resultados sugerem que, além de forças de interação intermoleculares, efeitos de interação líquido/estrutura do solo podem estar exercendo importante papel na volatilização dos BTEX.The main objective of this paper was the quantitative evaluation of the ethanol's influence about the volatilization of BTEX (benzene, toluene, ethylbenzene and xylenes in a mixture of gasoline and anhydrous ethanol 25% (v/v in experimental columns that simulated soil contamination with gasoline/ethanol. All the BTEX presented expressive increase of volatilization rates in the gasoline-ethanol column. However, in terms of percentage, the highest and lowest volatilization grades were observed for toluene and benzene, respectively. In batch tests (control samples, with mixtures of gasoline ethanol with 0 and 25% (v/v in ethanol, no increase of the volatilization grade was observed for ethylbenzene and the volatilization grade for xylenes was reduced. Matrix effects seem to be, besides the intermolecular interaction forces, important contributions for the volatilization grade of BTEX in this kind of sample.

A field campaign for measurement of benzene in urban area of Venice

International Nuclear Information System (INIS)

Allegrini, I.; Febo, A.; Giliberti, C.; Giusto, M.; Montagnoli, M.

1996-01-01

A field campaign for the measurement of benzene and toluene in urban areas has been planned by the city of Venice in collaboration with CNR during the period June-July 1994. The measurements were provided by three automatic systems, available from the companies Chrompack, Elecos and Perkin-Elmer. The main aims of this campaign were to collect information on spatial and temporal distribution of these pollutants, in order to estimate the exposure risk for people in an urban polluted environment, and to identify the most reliable and accurate systems to measure this pollutant. From the comparison between the temporal trend of benzene and natural radioactivity it can be deduced that the concentration levels of primary pollutants at ground state are not simply linked to emissions, but they are strongly modulated by atmospheric diffusion processes. The reliability of the experimental results was demonstrated by a statistical treatment, and it was shown that it is necessary to carry out measurements at sufficiently high frequencies to represent the real environmental situation

Benzene destruction in claus process by sulfur dioxide: A reaction kinetics study

KAUST Repository

Sinha, Sourab

2014-07-02

Benzene, toluene and xylene (BTX) are present as contaminants in the H 2S gas stream entering a Claus furnace. The exhaust gases from the furnace enter catalytic units, where BTX form soot particles. These particles clog and deactivate the catalysts. A solution to this problem is BTX oxidation before the gases enter catalyst beds. This work presents a theoretical investigation on benzene oxidation by SO2. Density functional theory is used to develop a detailed mechanism for phenyl radical -SO2 interactions. The mechanism begins with SO2 addition to phenyl radical after overcoming an energy barrier of 6.4 kJ/mol. This addition reaction is highly exothermic, where a reaction energy of 182 kJ/mol is released. The most favorable pathway involves O-S bond breakage, leading to the release of SO. A remarkable similarity between the pathways for phenyl radical oxidation by O2 and its oxidation by SO2 is observed. The reaction rate constants are also evaluated to facilitate process simulations. © 2014 American Chemical Society.

Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

KAUST Repository

Atanda, Luqman

2011-07-01

Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

Personal exposure to volatile organic compounds in the Czech Republic.

Science.gov (United States)

Svecova, Vlasta; Topinka, Jan; Solansky, Ivo; Sram, Radim J

2012-09-01

Personal exposures to volatile organic compounds (VOCs) were measured in the three industrial cities in the Czech Republic, Ostrava, Karvina and Havirov, while the city of Prague served as a control in a large-scale molecular epidemiological study identifying the impacts of air pollution on human health. Office workers from Ostrava and city policemen from Karvina, Havirov and Prague were monitored in the winter and summer of 2009. Only adult non-smokers participated in the study (N=160). Radiello-diffusive passive samplers were used to measure the exposure to benzene, toluene, ethylbenzene, meta- plus para-xylene and ortho-xylene (BTEX). All participants completed a personal questionnaire and a time-location-activity diary (TLAD). The average personal BTEX exposure levels in both seasons were 7.2/34.3/4.4/16.1 μg/m(3), respectively. The benzene levels were highest in winter in Karvina, Ostrava and Prague: 8.5, 7.2 and 5.3 μg/m(3), respectively. The personal exposures to BTEX were higher than the corresponding stationary monitoring levels detected in the individual localities (Pfireplace or gas stove, automobile use and being in a restaurant were important predictors for benzene personal exposure. Ostrava's outdoor benzene pollution was a significant factor increasing the exposure of the Ostrava study participants in winter (P<0.05).

Development of a Small, Inexpensive, and Field-deployable Gas Chromatograph for the Automated Collection, Separation, and Analysis of Gas-phase Organic Compounds

Science.gov (United States)

Skog, K.; Xiong, F.; Gentner, D. R.

2017-12-01

The identification and quantification of gas-phase organic compounds, like volatile organic compounds (VOCs), in the atmosphere relies on separation of complex mixtures and sensitive detection. Gas chromatography (GC) is widely applied, but relies on the need for high-purity compressed gases for separation and, often for detection. We have developed a low-cost, compact GC-based system for the collection and quantitative chemical speciation of complex mixtures of common atmospheric VOCs without the need for compressed high-purity gases or expensive detectors. We present results of lab and field testing against a commercially-available GC system. At optimized linear velocities challenging VOC pairs of similar volatility were resolved within 30 minutes, including n- and i-pentane; n-pentane and isoprene; and ethylbenzene and m/p-xylene. For 5-30 minute samples, we observe ppt-level detection limits for common VOCs such as benzene, toluene, ethylbenzene, xylenes, alpha-pinene, and limonene. We also present results of in-field use for VOC measurements. In all, this instrument is accurate, precise, small, and inexpensive (<$2500). Its lack of compressed gas cylinders make it ideal for field deployment and has been demonstrated to produce similar quality data to available GC technology.

[Emission characteristics and safety evaluation of volatile organic compounds in manufacturing processes of automotive coatings].

Science.gov (United States)

Zeng, Pei-Yuan; Li, Jian-Jun; Liao, Dong-Qi; Tu, Xiang; Xu, Mei-Ying; Sun, Guo-Ping

2013-12-01

Emission characteristics of volatile organic compounds (VOCs) were investigated in an automotive coating manufacturing enterprise. Air samples were taken from eight different manufacturing areas in three workshops, and the species of VOCs and their concentrations were measured by gas chromatography-mass spectrometry (GC-MS). Safety evaluation was also conducted by comparing the concentration of VOCs with the permissible concentration-short term exposure limit (PC-STEL) regulated by the Ministry of Health. The results showed that fifteen VOCs were detected in the indoor air of the automotive coatings workshop, including benzene, toluene, ethylbenzene, xylene, ethyl acetate, butyl acetate, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, trimethylbenzene and ethylene glycol monobutyl ether, Their concentrations widely ranged from 0.51 to 593.14 mg x m(-3). The concentrations of TVOCs were significantly different among different manufacturing processes. Even in the same manufacturing process, the concentrations of each component measured at different times were also greatly different. The predominant VOCs of indoor air in the workshop were identified to be ethylbenzene and butyl acetate. The concentrations of most VOCs exceeded the occupational exposure limits, so the corresponding control measures should be taken to protect the health of the workers.

Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

KAUST Repository

Al-Khattaf, Sulaiman

2008-01-01

Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported

Relating BTEX degradation to the biogeochemistry of an anaerobic aquifer

International Nuclear Information System (INIS)

Toze, S.G.; Power, T.R.; Davis, G.B.

1995-01-01

Trends in chemical and microbiological parameters in a petroleum hydrocarbon plume within anaerobic groundwater have been studied. Previously, microbial degradation of the hydrocarbon compounds had been substantiated by the use of deuterated hydrocarbons to determine natural (intrinsic) degradation rates within the contaminant plume. Here, sulfate concentration decreases, Eh decreases, and hydrogen sulfide and bicarbonate concentration increases are shown to be associated with the contaminant plume. These trends indicate microbial degradation of the benzene, toluene, ethylbenzene, and xylene (BTEX) compounds by sulfate-reducing bacteria. Stoichiometry indicates that other consortia of bacteria play a role in the degradation of the hydrocarbons. Total microbial cell numbers were higher within the plume than in the uncontaminated groundwater. There is, however, no direct correlation between total microbial cell numbers, and BTEX, sulfate, bicarbonate, and hydrogen sulfide concentrations within the plume

Analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of Happy Valley-Goose Bay, eastern Canadian subarctic

DEFF Research Database (Denmark)

Fonkwe, Merline L D; Trapp, Stefan

2016-01-01

-gas chromatography-mass spectrometry. BTEX compounds were detected in tree cores, corroborating known groundwater contamination. A zone of anomalously high concentrations of total BTEX constituents was identified and recommended for monitoring by groundwater wells. Tree cores collected outside the landfill site......This research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (BTEX) compounds and methyl tertiary-butyl ether (MTBE) in groundwater in eastern Canada subarctic environments, using a former landfill site in the remote community of Happy...... Valley-Goose Bay, Labrador. Petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. Tree cores were taken from trembling aspen, black spruce, and white birch and analyzed by headspace...

Conversion of kraft lignin over hierarchical MFI zeolite.

Science.gov (United States)

Kim, Seong-Soo; Lee, Hyung Won; Ryoo, Ryong; Kim, Wookdong; Park, Sung Hoon; Jeon, Jong-Ki; Park, Young-Kwon

2014-03-01

Catalytic pyrolysis of kraft lignin was carried out using pyrolysis gas chromatography/mass spectrometry. Hierarchical mesoporous MFI was used as the catalyst and another mesoporous material Al-SBA-15 was also used for comparison. The characteristics of mesoporous MFI were analyzed by X-ray diffraction patterns, N2 adsorption-desorption isotherms, and temperature programmed desorption of NH3. Two catalyst/lignin mass ratios were tested: 5/1 and 10/1. Aromatics and alkyl phenolics were the main products of the catalytic pyrolysis of lignin over mesoporous MFI. In particular, the yields of mono-aromatics such as benzene, toluene, ethylbenzene, and xylene were increased substantially by catalytic upgrading. Increase in the catalyst dose enhanced the production of aromatics further, which is attributed to decarboxylation, decarbonlyation, and aromatization reactions occurring over the acid sites of mesoporous MFI.

EVALUATION OF PETROLEUM HYDROCARBONS ELUTION FROM SOIL

Directory of Open Access Journals (Sweden)

Janina Piekutin

2015-06-01

Full Text Available The paper presents studies on oil removal from soil by means of water elution with a help of shaking out the contaminants from the soil. The tests were performed on simulated soil samples contaminated with a mixture of petroleum hydrocarbons. The study consisted in recording the time influence and the number of elution cycles to remove contaminants from the soil. The samples were then subject to the determination of petroleum hydrocarbons, aliphatic hydrocarbons, and BTEX compounds (benzene, toluene, ethylbenzene, xylene. Due to adding various concentrations of petroleum into particular soil samples and applying different shaking times, it was possible to find out the impact of petroleum content and sample shaking duration on the course and possibility of petroleum substances removal by means of elution process.

Successive changes in community structure of an ethylbenzene-degrading sulfate-reducing consortium.

Science.gov (United States)

Nakagawa, Tatsunori; Sato, Shinya; Yamamoto, Yoko; Fukui, Manabu

2002-06-01

The microbial community structure and successive changes in a mesophilic ethylbenzene-degrading sulfate-reducing consortium were for the first time clarified by the denaturing gradient gel electrophoresis (DGGE) analysis of the PCR amplified 16S rRNA gene fragments. At least ten bands on the DGGE gel were detected in the stationary phase. Phylogenetic analysis of the DGGE bands revealed that the consortium consisted of different eubacterial phyla including the delta subgroup of Proteobacteria, the order Sphingobacteriales, the order Spirochaetales, and the unknown bacterium. The most abundant band C was closely related to strain mXyS1, an m-xylene-degrading sulfate-reducing bacterium (SRB), and occurred as a sole band on DGGE gels in the logarithmic growth phase that 40% ethylbenzene was consumed accompanied by sulfide production. During further prolonged incubation, the dominancy of band C did not change. These results suggest that SRB corresponds to the most abundant band C and contributes mainly to the degradation of ethylbenzene coupled with sulfate reduction.

Selective and Stable Ethylbenzene Dehydrogenation to Styrene over Nanodiamonds under Oxygen-lean Conditions.

Science.gov (United States)

Diao, Jiangyong; Feng, Zhenbao; Huang, Rui; Liu, Hongyang; Hamid, Sharifah Bee Abd; Su, Dang Sheng

2016-04-07

For the first time, significant improvement of the catalytic performance of nanodiamonds was achieved for the dehydrogenation of ethylbenzene to styrene under oxygen-lean conditions. We demonstrated that the combination of direct dehydrogenation and oxidative dehydrogenation indeed occurred on the nanodiamond surface throughout the reaction system. It was found that the active sp(2)-sp(3) hybridized nanostructure was well maintained after the long-term test and the active ketonic carbonyl groups could be generated in situ. A high reactivity with 40% ethylbenzene conversion and 92% styrene selectivity was obtained over the nanodiamond catalyst under oxygen-lean conditions even after a 240 h test, demonstrating the potential of this procedure for application as a promising industrial process for the ethylbenzene dehydrogenation to styrene without steam protection. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetics of Natural Attenuation: Review of the Critical Chemical Conditions and Measurements at Bore Scale

Directory of Open Access Journals (Sweden)

O. Atteia

2002-01-01

Full Text Available This paper describes the chemical conditions that should favour the biodegradation of organic pollutants. Thermodynamic considerations help to define the reaction that can occur under defined chemical conditions. The BTEX (benzene, toluene, ethylbenzene, and xylene degradation is focused on benzene, as it is the most toxic oil component and also because it has the slowest degradation rate under most field conditions. Several studies on benzene degradation allow the understanding of the basic degradation mechanisms and their importance in field conditions. The use of models is needed to interpret field data when transport, retardation, and degradation occur. A detailed comparison of two existing models shows that the limits imposed by oxygen transport must be simulated precisely to reach correct plumes shapes and dimensions, and that first-order kinetic approaches may be misleading. This analysis led us to develop a technique to measure directly biodegradation in the field. The technique to recirculate water at the borehole scale and the CO2 analysis are depicted. First results of biodegradation show that this technique is able to easily detect the degradation of 1 mg/l of hydrocarbons and that, in oxic media, a fast degradation rate of mixed fuel is observed.

Ethylbenzene-induced hearing loss, neurobehavioral function, and neurotransmitter alterations in petrochemical workers.

Science.gov (United States)

Zhang, Ming; Wang, Yanrang; Wang, Qian; Yang, Deyi; Zhang, Jingshu; Wang, Fengshan; Gu, Qing

2013-09-01

To estimate hearing loss, neurobehavioral function, and neurotransmitter alteration induced by ethylbenzene in petrochemical workers. From two petrochemical plants, 246 and 307 workers exposed to both ethylbenzene and noise were recruited-290 workers exposed to noise only from a power station plant and 327 office personnel as control group, respectively. Hearing and neurobehavioral functions were evaluated. Serum neurotransmitters were also determined. The prevalence of hearing loss was much higher in petrochemical groups than that in power station and control groups (P workers (P hearing loss, neurobehavioral function impairment, and imbalance of neurotransmitters.

Spatial Variability and Application of Ratios between BTEX in Two Canadian Cities

Directory of Open Access Journals (Sweden)

Lindsay Miller

2011-01-01

Full Text Available Spatial monitoring campaigns of volatile organic compounds were carried out in two similarly sized urban industrial cities, Windsor and Sarnia, ON, Canada. For Windsor, data were obtained for all four seasons at approximately 50 sites in each season (winter, spring, summer, and fall over a three-year period (2004, 2005, and 2006 for a total of 12 sampling sessions. Sampling in Sarnia took place at 37 monitoring sites in fall 2005. In both cities, passive sampling was done using 3M 3500 organic vapor samplers. This paper characterizes benzene, toluene, ethylbenzene, o, and (m + p-xylene (BTEX concentrations and relationships among BTEX species in the two cities during the fall sampling periods. BTEX concentration levels and rank order among the species were similar between the two cities. In Sarnia, the relationships between the BTEX species varied depending on location. Correlation analysis between land use and concentration ratios showed a strong influence from local industries. Use one of the ratios between the BTEX species to diagnose photochemical age may be biased due to point source emissions, for example, 53 tonnes of benzene and 86 tonnes of toluene in Sarnia. However, considering multiple ratios leads to better conclusions regarding photochemical aging. Ratios obtained in the sampling campaigns showed significant deviation from those obtained at central monitoring stations, with less difference in the (m + p/E ratio but better overall agreement in Windsor than in Sarnia.

The emissions of monoaromatic hydrocarbons from small polymeric toys placed in chocolate food products.

Science.gov (United States)

Marć, Mariusz; Formela, Krzysztof; Klein, Marek; Namieśnik, Jacek; Zabiegała, Bożena

2015-10-15

The article presents findings on the emissions of selected monoaromatic hydrocarbons from children's toys placed in chocolate food products. The emission test system involved the application of a new type of microscale stationary emission chamber, μ-CTE™ 250. In order to determine the type of the applied polymer in the manufacture of the tested toys, Fourier transform infrared spectroscopy and thermogravimetric analysis coupled with differential scanning calorimetry were used. It was found that the tested toy components or the whole toys (figurines) are made of two main types of polymers: polyamide and acrylonitrile-butadiene-styrene copolymer. Total number of studied small polymeric toys was 52. The average emissions of selected monoaromatic hydrocarbons from studied toys made of polyamide were as follows: benzene: 0.45 ± 0.33 ng/g; toluene: 3.3 ± 2.6 ng/g; ethylbenzene: 1.4 ± 1.4 ng/g; p,m-xylene: 2.5 ± 4.5 ng/g; and styrene: 8.2 ± 9.9 ng/g. In the case of studied toys made of acrylonitrile-butadiene-styrene copolymer the average emissions of benzene, toluene, ethylbeznene, p,m-xylene and styrene were: 0.31 ± 0.29 ng/g; 2.5 ± 1.4 ng/g; 4.6 ± 8.9 ng/g; 1.4 ± 1.1 ng/g; and 36 ± 44 ng/g, respectively. Copyright © 2015. Published by Elsevier B.V.

Tailored ceria nanoparticles for CO2 mediated ethylbenzene dehydrogenation

NARCIS (Netherlands)

Kovacevic, M.

2016-01-01

Styrene production via ethylbenzene dehydrogenation (EBDH) is one of the ten most important petrochemical processes. Possessing highly reactive double bond which facilitates self-polymerization and polymerization with other monomers, styrene is the fourth utmost essential bulk monomer at present.

Exposure Evaluation for Benzene, Lead and Noise in Vehicle and Equipment Repair Shops

Energy Technology Data Exchange (ETDEWEB)

Sweeney, Lynn C. [Washington State Univ., Pullman, WA (United States)

2013-04-01

An exposure assessment was performed at the equipment and vehicle maintenance repair shops operating at the U. S. Department of Energy Hanford site, in Richland, Washington. The maintenance shops repair and maintain vehicles and equipment used in support of the Hanford cleanup mission. There are three general mechanic shops and one auto body repair shop. The mechanics work on heavy equipment used in construction, cranes, commercial motor vehicles, passenger-type vehicles in addition to air compressors, generators, and farm equipment. Services include part fabrication, installation of equipment, repair and maintenance work in the engine compartment, and tire and brake services. Work performed at the auto body shop includes painting and surface preparation which involves applying body filler and sanding. 8-hour time-weighted-average samples were collected for benzene and noise exposure and task-based samples were collected for lead dust work activities involving painted metal surfaces. Benzene samples were obtained using 3M™ 3520 sampling badges and were analyzed for additional volatile organic compounds. These compounds were selected based on material safety data sheet information for the aerosol products used by the mechanics for each day of sampling. The compounds included acetone, ethyl ether, toluene, xylene, VM&P naphtha, methyl ethyl ketone, and trichloroethylene. Laboratory data for benzene, VM&P naphtha, methyl ethyl ketone and trichloroethylene were all below the reporting detection limit. Airborne concentrations for acetone, ethyl ether, toluene and xylene were all less than 10% of their occupational exposure limit. The task-based samples obtained for lead dusts were submitted for a metal scan analysis to identify other metals that might be present. Laboratory results for lead dusts were all below the reporting detection limit and airborne concentration for the other metals observed in the samples were less than 10% of the occupational exposure limit

Observations of atmospheric monoaromatic hydrocarbons at urban, semi-urban and forest environments in the Amazon region

Science.gov (United States)

Paralovo, Sarah L.; Borillo, Guilherme C.; Barbosa, Cybelli G. G.; Godoi, Ana Flavia L.; Yamamoto, Carlos I.; de Souza, Rodrigo A. F.; Andreoli, Rita V.; Costa, Patrícia S.; Almeida, Gerson P.; Manzi, Antonio O.; Pöhlker, Christopher; Yáñez-Serrano, Ana M.; Kesselmeier, Jürgen; Godoi, Ricardo H. M.

2016-03-01

The Amazon region is one of the most significant natural ecosystems on the planet. Of special interest as a major study area is the interface between the forest and Manaus city, a state capital in Brazil embedded in the heart of the Amazon forest. In view of the interactions between natural and anthropogenic processes, an integrated experiment was conducted measuring the concentrations of the volatile organic compounds (VOCs) benzene, toluene, ethylbenzene and meta, ortho, para-xylene (known as BTEX), all of them regarded as pollutants with harmful effects on human health and vegetation and acting also as important precursors of tropospheric ozone. Furthermore, these compounds also take part in the formation of secondary organic aerosols, which can influence the pattern of cloud formation, and thus the regional water cycle and climate. The samples were collected in 2012/2013 at three different sites: (i) The Amazon Tall Tower Observatory (ATTO), a pristine rain forest region in the central Amazon Basin; (ii) Manacapuru, a semi-urban site located southwest and downwind of Manaus as a preview of the Green Ocean Amazon Experiment (GoAmazon 2014/15); and (iii) the city of Manaus (distributed over three sites). Results indicate that there is an increase in pollutant concentrations with increasing proximity to urban areas. For instance, the benzene concentration ranges were 0.237-19.6 (Manaus), 0.036-0.948 (Manacapuru) and 0.018-0.313 μg m-3 (ATTO). Toluene ranges were 0.700-832 (Manaus), 0.091-2.75 μg m-3 (Manacapuru) and 0.011-4.93 (ATTO). For ethylbenzene, they were 0.165-447 (Manaus), 0.018-1.20 μg m-3 (Manacapuru) and 0.047-0.401 (ATTO). Some indication was found for toluene to be released from the forest. No significant difference was found between the BTEX levels measured in the dry season and the wet seasons. Furthermore, it was observed that, in general, the city of Manaus seems to be less impacted by these pollutants than other cities in Brazil and in other

Estimation of Partition Coefficients of Benzene, Toluene, Ethylbenzene, and ρ-Xylene by Consecutive Extraction with Solid Phase Microextraction

International Nuclear Information System (INIS)

Eom, In Yong

2011-01-01

The results show that the partition coefficients of the BTEX compound can be estimated using the SPME method under the consecutive extraction mode. The proposed technique is much simpler than previously reported methods. Its novelty is that it eliminated the calibration step in the GC/FID, i. e., liquid injection method. The use of the autosampler for the SPME fiber can facilitate the adoption of consecutive extractions; thus, it allows estimation of the partition coefficients of various analytes. Recently, GC/MS has increasingly been used in analytical laboratories; this may facilitate the identification of an unknown analyte as well as the computation of the corresponding partition coefficients with the proposed method. It is very important to use partition coefficients of organic pollutants to predict their fate in the environment. A liquid-liquid extraction technique was used to determine the partition coefficients of organic compounds between water and organic solvent. The concentration of the target compounds must be determined after equilibrium is established between the two phases. The partition coefficients can be estimated using the capacity factors of HPLC and GC

Review: Microbial degradation of toluene | Gopinath | African ...

African Journals Online (AJOL)

In spite of positive potential application, toluene results in many mishaps especially health hazards; hence amputation of toluene is crucial for human welfare as well as environmental issues. This review deals with destruction of toluene using microbial degradation. The overall aerobic biodegradation of toluene into carbon ...

Emission of BTEX and PAHs from molding sands with furan cold setting resins containing different contents of free furfuryl alcohol during production of cast iron

Directory of Open Access Journals (Sweden)

Mariusz Holtzer

2015-11-01

Full Text Available At present, furan resin is the largest selling no-bake system of moulding sands. The most commonly used furan no-bake binders (FNB are condensation products of furfuryl alcohol (FA urea, formaldehyde and phenol. They are generally cured by exposure to organic sulfonic acids. FNB provide excellent mold and core strength, cure rapidly and allow the sand to be reclaimed at fairly high yields, generally 75%-80%, especially in applications where due allowance is made for the need to keep total sulfur content below 0.1%. However, due to probable carcinogenic properties of furfuryl alcohol, the EU Directive limits the content of this substance (in a monomer form in resin to 25%. The classification of furfuryl alcohol and the resulting furan resin products has changed from "harmful" to "toxic" by inhalation? The aim of this study was to determine the effect of free furfuryl alcohol content in the resin on the emission of harmful substances from the BTEX (Benzene Toluene Ethylbenzene & Xylene and PAHs (polycyclic aromatic hydrocarbon group exposed to high temperature and how it affects the emissions allowance of reclaimed sand in the matrix. Three resins from a leading manufacturer were examined, which contain a free furfuryl alcohol content of 71%-72%, about 50% and < 25%, respectively. The hardener for each resin was 65% aqueous solution of paratoluenesulfonic acid. Tests were carried out in semi-industrial conditions where liquid cast-iron was poured into sample sand mold at 1,350 ìC. The matrix of the studied sands was reclaimed in the amount of 0, 50%, 100%, respectively. With the increase of free furfuryl alcohol content, the volume of evolved gases decreased. For all resins the main component from the BTEX group dominating in the emitted gases was benzene; however toluene also appeared in the amount of a few percentages. In contrast, ethylbenzene and xylenes occurred only in the gases emitted from resin-bonded sands with the largest furfuryl

Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons

Science.gov (United States)

Cui, Long; Zhang, Zhou; Huang, Yu; Lee, Shun Cheng; Blake, Donald Ray; Ho, Kin Fai; Wang, Bei; Gao, Yuan; Wang, Xin Ming; Kwok Keung Louie, Peter

2016-12-01

Volatile organic compound (VOC) control is an important issue of air quality management in Hong Kong because ozone formation is generally VOC limited. Several oxygenated volatile organic compound (OVOC) and VOC measurement techniques - namely, (1) offline 2,4-dinitrophenylhydrazine (DNPH) cartridge sampling followed by high-performance liquid chromatography (HPLC) analysis; (2) online gas chromatography (GC) with flame ionization detection (FID); and (3) offline canister sampling followed by GC with mass spectrometer detection (MSD), FID, and electron capture detection (ECD) - were applied during this study. For the first time, the proton transfer reaction-mass spectrometry (PTR-MS) technique was also introduced to measured OVOCs and VOCs in an urban roadside area of Hong Kong. The integrated effect of ambient relative humidity (RH) and temperature (T) on formaldehyde measurements by PTR-MS was explored in this study. A Poly 2-D regression was found to be the best nonlinear surface simulation (r = 0.97) of the experimental reaction rate coefficient ratio, ambient RH, and T for formaldehyde measurement. This correction method was found to be better than correcting formaldehyde concentrations directly via the absolute humidity of inlet sample, based on a 2-year field sampling campaign at Mong Kok (MK) in Hong Kong. For OVOC species, formaldehyde, acetaldehyde, acetone, and MEK showed good agreements between PTR-MS and DNPH-HPLC with slopes of 1.00, 1.10, 0.76, and 0.88, respectively, and correlation coefficients of 0.79, 0.75, 0.60, and 0.93, respectively. Overall, fair agreements were found between PTR-MS and online GC-FID for benzene (slope = 1.23, r = 0.95), toluene (slope = 1.01, r = 0.96) and C2-benzenes (slope = 1.02, r = 0.96) after correcting benzene and C2-benzenes levels which could be affected by fragments formed from ethylbenzene. For the intercomparisons between PTR-MS and offline canister measurements by GC-MSD/FID/ECD, benzene showed good agreement

Hydrogen bonding in (substituted benzene)·(water)n clusters with n≤4

International Nuclear Information System (INIS)

Barth, H.-D.; Buchhold, K.; Djafari, S.; Reimann, B.; Lommatzsch, U.; Brutschy, B.

1998-01-01

Infrared ion-depletion spectroscopy, a double resonance method combining vibrational predissociation with resonant two-photon ionization (R2PI) spectroscopy, has been applied to study mixed clusters of the type (substituted benzene)·(H 2 O) n with n≤4. The UV chromophores were p-difluorobenzene, fluorobenzene, benzene, toluene, p-xylene and anisole. From the IR depletion spectra in the region of the OH stretching vibrations it could be shown that the water molecules are attached as subclusters to the chromophores. Size and configuration of the subclusters could be deduced from the IR depletion spectra. In the anisole·(H 2 O) 1 a nd 2 complexes the water clusters form an ordinary hydrogen bond to the oxygen atom of the methoxy group. In all other mixed complexes a π-hydrogen bond is formed between one of the free OH groups of a water subcluster and the π-system of the chromophore. According to the strength of this interaction the frequency of the respective absorption band exhibits a characteristic red-shift which could be related to the total atomic charges in the aromatic ring. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

[Changes in the peripheral blood of workers engaged in ethylbenzene-styrene and synthetic rubber and latex manufacture].

Science.gov (United States)

Khristeva, V

1986-01-01

A total of 67 workers were examined from the production of "Ethyl benzene-styrene" and 184 workers from the production of "Synthetic rubber and latex", as well as a control group of 59 employees. The workers from the first production are exposed to the effect of styrene, ethyl benzene and toluene. The concentrations of the substances surpass MAC, with several times, at the majority of the working places. The workers with a length of service over 10 years predominate. The workers from the second production are exposed to the combined effect of styrene and divinyl, their concentrations fluctuating from 2 to 8 times over MAC. The workers with a length of service over 10 years are 71.7%. The deviations, established in the hematological indices studied are compared with the results from a study on the workers from those productions of 6 years ago. Dynamics in the changes was established among the workers from the production of "Synthetic rubber and latex", associated with the duration of occupational exposure to styrene and divinyl. In case of a shorter length of service, the deviations are functional (reduction of peroxidase activity in granulocytes), increase of hemoglobin and hematocrit, associated with the adaptive reaction of organism. Pronounced anemic syndrome was established in a considerable number (24 workers) after an exposure of 10 years as well as lymphocytosis (35 subjects) and leukopenia (9 subjects).

Fate and transport of petroleum hydrocarbons in soil and ground water at Big South Fork National River and Recreation Area, Tennessee and Kentucky, 2002-2003

Science.gov (United States)

Williams, Shannon D.; Ladd, David E.; Farmer, James

2006-01-01

In 2002 and 2003, the U.S. Geological Survey (USGS), by agreement with the National Park Service (NPS), investigated the effects of oil and gas production operations on ground-water quality at Big South Fork National River and Recreation Area (BISO) with particular emphasis on the fate and transport of petroleum hydrocarbons in soils and ground water. During a reconnaissance of ground-water-quality conditions, samples were collected from 24 different locations (17 springs, 5 water-supply wells, 1 small stream, and 1 spring-fed pond) in and near BISO. Benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were not detected in any of the water samples, indicating that no widespread contamination of ground-water resources by dissolved petroleum hydrocarbons probably exists at BISO. Additional water-quality samples were collected from three springs and two wells for more detailed analyses to obtain additional information on ambient water-quality conditions at BISO. Soil gas, soil, water, and crude oil samples were collected at three study sites in or near BISO where crude oil had been spilled or released (before 1993). Diesel range organics (DRO) were detected in soil samples from all three of the sites at concentrations greater than 2,000 milligrams per kilogram. Low concentrations (less than 10 micrograms per kilogram) of BTEX compounds were detected in lab-analyzed soil samples from two of the sites. Hydrocarbon-degrading bacteria counts in soil samples from the most contaminated areas of the sites were not greater than counts for soil samples from uncontaminated (background) sites. The elevated DRO concentrations, the presence of BTEX compounds, and the low number of -hydrocarbon-degrading bacteria in contaminated soils indicate that biodegradation of petroleum hydrocarbons in soils at these sites is incomplete. Water samples collected from the three study sites were analyzed for BTEX and DRO. Ground-water samples were collected from three small springs at the

Aromatic hydrocarbons in a controlled ecological life support system during a 4-person-180-day integrated experiment.

Science.gov (United States)

Dai, Kun; Yu, Qingni; Zhang, Zhou; Wang, Yuan; Wang, Xinming

2018-01-01

Indoor air quality is vital to the health and comfort of people who live inside a controlled ecological life support system (CELSS) built for long-term space explorations. Here we measured aromatic hydrocarbons to assess their sources and health risks during a 4-person-180-day integrated experiment inside a CELSS with four cabins for growing crops, vegetables and fruits and other two cabins for working, accommodations and resources management. During the experiment, the average concentrations of benzene, ethylbenzene, m,p-xylenes and o-xylene were found to decrease exponentially from 7.91±3.72, 37.2±35.2, 100.8±111.7 and 46.8±44.1μg/m 3 to 0.39±0.34, 1.4±0.5, 2.8±0.7 and 2.1±0.9μg/m 3 , with half-lives of 25.3, 44.8, 44.7 and 69.3days, respectively. Toluene to benzene ratios indicated emission from construction materials or furniture to be a dominant source for toluene, and concentrations of toluene fluctuated during the experiment largely due to the changing sorption by growing plants. The cancer and no-cancer risks based on exposure pattern of the crews were insignificant in the end of the experiment. This study also suggested that using low-emitting materials/furniture, growing plants and purifying air actively would all help to lower hazardous air pollutants inside CELSS. Broadly, the results would benefit not only the development of safe and comfort life support systems for space exploration but also the understanding of interactions between human and the total environment in closed systems. Copyright © 2017 Elsevier B.V. All rights reserved.

The Great Bear Flare Pit Project : review of work to date

International Nuclear Information System (INIS)

Ridal, J.; Lean, D.; Findlay, S.C.

1998-01-01

Published information regarding potential toxic agents associated with flare emissions and a study to determine the risk posed to Treaty 8 First Nations (T8FN) peoples and wildlife was reviewed as part of the Great Bear Flare Pit Project (GBFPP). The project is concerned with the study of water and soil contamination in the immediate vicinity of flare pits in the Del Rio, Doig basin, Blueberry River, and Halfway River regions of T8FN lands in Alberta. The GBFPP has established good baseline data on metal contamination, and other contaminants such as benzene, toluene, ethylbenzene, xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAHs) in the immediate vicinity of selected flare pits. Based on a critical assessment of reports published to date a series of prioritized recommendations for further research are made. 18 refs., 2 tabs

Evaluating intrinsic bioremediation at five sour gas processing facilities in Alberta

International Nuclear Information System (INIS)

Armstrong, J. E.; Moore, B. J.; Sevigny, J. H.; Forrester, P. I.

1997-01-01

Mass attenuation through intrinsic bioremediation of the aromatic hydrocarbons benzene, toluene, ethylbenzene and xylene (BTEX) was studied at four facilities in Alberta. The objective of the study was to assess whether intrinsic bioremediation could attenuate BTEX-contaminated groundwater plumes at the four sites. The depletion of electron acceptors, and the enriched metabolic byproducts within the BTEX plumes indicate that BTEX biodegradation is occurring at all four sites. Bacterial plate counts were generally higher at three of the sites and lower at one site. At the three sites microcosm experiments indicated aerobic biodegradation, while anaerobic biodegradation was observed at only two sites after four to five months incubation. Theoretical estimates of the biodegradation potential were calculated for each site with intrinsic bioremediation appearing to have bioremediation potential at three of the sites. 13 refs., 4 tabs., 4 figs

Microbes safely, effectively bioremediate oil field pits

International Nuclear Information System (INIS)

Shaw, B.; Block, C.S.; Mills, C.H.

1995-01-01

Natural and augmented bioremediation provides a safe, environmental, fast, and effective solution for removing hydrocarbon stains from soil. In 1992, Amoco sponsored a study with six bioremediation companies, which evaluated 14 different techniques. From this study, Amoco continued using Environmental Protection Co.'s (EPC) microbes for bioremediating more than 145 sites near Farmington, NM. EPC's microbes proved effective on various types of hydrocarbon molecules found in petroleum stained soils from heavy crude and paraffin to volatiles such as BTEX (benzene, toluene, ethylbenzene, xylene) compounds. Controlled laboratory tests have shown that these microbes can digest the hydrocarbon molecules with or without free oxygen present. It is believed that this adaptation gives these microbes their resilience. The paper describes the bioremediation process, environmental advantages, in situ and ex situ bioremediation, goals of bioremediation, temperature effects, time, cost, and example sites that were treated

In situ closed-loop bioremediation: Rapid closure in a northern climate

International Nuclear Information System (INIS)

Weymann, D.F.; Hammerbeck, L.M.

1995-01-01

In situ closed-loop bioremediation was employed to achieve site closure at a former railyard in Minneapolis, Minnesota. Soil and groundwater were contaminated with gasoline. The closed-loop remediation system design incorporated three downgradient groundwater recovery wells and a low-pressure pipe infiltration gallery. Aboveground treatment of recovered groundwater was provided by a fixed-film bioreactor. The total reported benzene, toluene, ethylbenzene, and xylenes (BTEX)-removal efficiency of the bioreactor ranged from 98.8% to 100%. Concentrations of BTEX components in groundwater wells were reduced by 45% to 98%. The cleanup goals set by the Minnesota Pollution Control Agency were met within the first 6 months of treatment, and the remediation system was shut down after 20 months of operation. This project further demonstrates the effectiveness of reactor-based, closed-loop in situ bioremediation at sites with favorable conditions

Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran

Science.gov (United States)

Hazrati, Sadegh; Rostami, Roohollah; Farjaminezhad, Manoochehr; Fazlzadeh, Mehdi

2016-05-01

BTEX concentrations in indoor and outdoor air of 50 homes were studied in Ardabil city and their influencing parameters including; heating system, using gas stove and samovar, tobacco smoking, the floors in which the monitored homes were located, and kitchen plan were considered in the study. Risk assessment analysis was carried out with the obtained concentrations based on EPA IRIS reference doses. BTEX compounds were sampled by charcoal tubes and the samples were analyzed by a GC-FID. Concentrations of benzene (15.18 μg/m3 vs. 8.65 μg/m3), toluene (69.70 μg/m3 vs. 40.56 μg/m3), ethylbenzene (12.07 μg/m3 vs. 4.92 μg/m3) and xylene (48.08 μg/m3 vs. 7.44 μg/m3) in indoor air were significantly (p < 0.05) higher than the levels quantified for outdoor air. The obtained concentrations of benzene were considerably higher than the recommended value of 5 μg/m3 established by Iran environmental protection organization. Among the BTEX compounds, benzene (HQ = 0.51) and xylene (HQ = 0.47) had notable hazard quotient and were the main pollutants responsible for high hazard index in the monitored homes (HI = 1.003). The results showed considerably high cancer risk for lifetime exposure to the indoor (125 × 10-6) and outdoor (71 × 10-6) benzene. Indoor benzene concentrations in homes were significantly influenced by type of heating system, story, and natural gas appliances.

Analysis of anaerobic BTX biodegradation in a subarctic aquifer using isotopes and benzylsuccinates.

Science.gov (United States)

McKelvie, Jennifer R; Lindstrom, Jon E; Beller, Harry R; Richmond, Sharon A; Sherwood Lollar, Barbara

2005-12-01

In situ biodegradation of benzene, toluene, and xylenes in a petroleum hydrocarbon contaminated aquifer near Fairbanks, Alaska was assessed using carbon and hydrogen compound specific isotope analysis (CSIA) of benzene and toluene and analysis of signature metabolites for toluene (benzylsuccinate) and xylenes (methylbenzylsuccinates). Carbon and hydrogen isotope ratios of benzene were between -25.9 per thousand and -26.8 per thousand for delta13C and -119 per thousand and -136 per thousand for delta2H, suggesting that biodegradation of benzene is unlikely at this site. However, biodegradation of both xylenes and toluene were documented in this subarctic aquifer. Biodegradation of xylenes was indicated by the presence of methylbenzylsuccinates with concentrations of 17-50 microg/L in three wells. Anaerobic toluene biodegradation was also indicated by benzylsuccinate concentrations of 10-49 microg/L in the three wells with the highest toluene concentrations (1500-5000 microg/L toluene). Since benzylsuccinate typically accounts for a very small fraction of the toluene present in groundwater (generally data is particularly valuable given the challenge of verifying biodegradation in subarctic environments where degradation rates are typically much slower than in temperate environments.

Evaluation of missing value methods for predicting ambient BTEX concentrations in two neighbouring cities in Southwestern Ontario Canada

Science.gov (United States)

Miller, Lindsay; Xu, Xiaohong; Wheeler, Amanda; Zhang, Tianchu; Hamadani, Mariam; Ejaz, Unam

2018-05-01

High density air monitoring campaigns provide spatial patterns of pollutant concentrations which are integral in exposure assessment. Such analysis can assist with the determination of links between air quality and health outcomes, however, problems due to missing data can threaten to compromise these studies. This research evaluates four methods; mean value imputation, inverse distance weighting (IDW), inter-species ratios, and regression, to address missing spatial concentration data ranging from one missing data point up to 50% missing data. BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations were measured in Windsor and Sarnia, Ontario in the fall of 2005. Concentrations and inter-species ratios were generally similar between the two cities. Benzene (B) was observed to be higher in Sarnia, whereas toluene (T) and the T/B ratios were higher in Windsor. Using these urban, industrialized cities as case studies, this research demonstrates that using inter-species ratios or regression of the data for which there is complete information, along with one measured concentration (i.e. benzene) to predict for missing concentrations (i.e. TEX) results in good agreement between predicted and measured values. In both cities, the general trend remains that best agreement is observed for the leave-one-out scenario, followed by 10% and 25% missing, and the least agreement for the 50% missing cases. In the absence of any known concentrations IDW can provide reasonable agreement between observed and estimated concentrations for the BTEX species, and was superior over mean value imputation which was not able to preserve the spatial trend. The proposed methods can be used to fill in missing data, while preserving the general characteristics and rank order of the data which are sufficient for epidemiologic studies.

Toluene stability Space Station Rankine power system

Science.gov (United States)

Havens, V. N.; Ragaller, D. R.; Sibert, L.; Miller, D.

1987-01-01

A dynamic test loop is designed to evaluate the thermal stability of an organic Rankine cycle working fluid, toluene, for potential application to the Space Station power conversion unit. Samples of the noncondensible gases and the liquid toluene were taken periodically during the 3410 hour test at 750 F peak temperature. The results obtained from the toluene stability loop verify that toluene degradation will not lead to a loss of performance over the 30-year Space Station mission life requirement. The identity of the degradation products and the low rates of formation were as expected from toluene capsule test data.

Leachate From Expanded Polystyrene Cups Is Toxic to Aquatic Invertebrates (Ceriodaphnia dubia

Directory of Open Access Journals (Sweden)

Clara Thaysen

2018-02-01

Full Text Available Expanded polystyrene (EPS products and their associated chemicals (e.g., styrenes are widespread in the marine environment. As a consequence, bans on their use for single-use packaging materials are being proposed in several municipalities. To better understand how science can inform decision-making, we looked at the available scientific literature about contamination and effects and conducted experiments to measure chemical leachate from polystyrene products and toxicity from the leachate. We conducted leaching experiments with common food matrices (water, soup broth, gravy, black coffee and coffee with cream and sugar at relevant temperatures (70 and 95°C that are consumed in or with several polystyrene products (coffee cup lids, polystyrene stir sticks, polystyrene spoons, EPS cups, EPS bowls, and EPS takeout containers. We analyzed each sample for styrene, ethylbenzene, toluene, benzene, meta- and para- xylene, isopropylbenzene, and isopropyltoluene—chemicals associated with polystyrene products. To determine whether the leachates are toxic, we conducted chronic toxicity tests, measuring survival and reproductive output in Ceriodaphnia dubia. Toxicity tests included nine treatments: seven concentrations of ethylbenzene, EPS cup leachate and a negative control. Overall, we found that temperature has a significant effect on leaching. We only detected leachates in trials conducted at higher temperature −95°C. Ethylbenzene was the only target analyte with final concentrations above the method limit of detection, and was present in the greatest concentrations in EPS and with soup broth. Measurable concentrations of ethylbenzene in the leachate ranged from 1.3 to 3.4 μg/L. In toxicity tests, the calculated LC50 for ethylbenzene was 14 mg/L and the calculated LC20 was 210 μg/L. For the treatment exposed to the EPS cup leachate, mortality was 40%—four times greater than the negative control. Finally, there was no significant difference (p

Health Risk Assessment and DNA Damage of Volatile Organic Compounds in Car Painting Houses

Directory of Open Access Journals (Sweden)

Patpida Siripongpokin

2014-06-01

Full Text Available Car painters who work near volatile organic compounds (VOCs sources, including paints, solvents and painting processes may be exposed to highly elevated VOCs levels. This study investigates air samples from car painting houses in Thailand to evaluate the health risks following inhalation exposure. Personal air samplings were obtained at nine garages in Phitsanulok, Thailand from June to September 2012. The concentrations of benzene, toluene, ethylbenzene, xylenes, and styrene in the air workplaces were significantly higher than in a control group of office workers (p < 0.05. Toluene, xylene and ethylbenzene were the most abundant species. However, all VOCs in these air samples were lower than TWA limit of Thailand and the OSHA standard. The lifetime cancer and non-cancer risks for the workers exposed to VOCs were also assessed. The average lifetime cancer risk was 41.0 (38.2-47.2 per million, which is in the acceptable risk. The average lifetime non-cancer risk, the HI, was 0.962 (0.643-1.397, which is well below the reference hazard level. Urine samples, collected after 8-h work periods which were analyzed for VOCs metabolites, including t,t muconic acid, hippuric acid, mandelic acid and m-hippuric acid, demonstrate that the average levels of metabolites in car painters and in controls were close. All VOCs metabolites in urine samples were lower than BEI of ACGIH standard. Blood samples, collected after 8-h work periods which were analyzed by single cell gel electrophoresis (comet assay. The DNA damage, assessed by tail moment, demonstrates that the average of tail moment in car painters were significantly higher than in the controls (p < 0.05.

Improved Understanding of Sources of Variability in Groundwater Sampling for Long-Term Monitoring Programs

Science.gov (United States)

2013-02-01

contents be construed as reflecting the official policy or position of the Department of Defense. Reference herein to any specific commercial product ... Ethylbenzene , and Vinyl Chloride. One pair of sample and duplicate results was reported as non-detect for Ethylbenzene and were not included in the RPD...by TestAmerica for 1,1-Dichloroethane, Benzene, Chlorobenzene, Ethylbenzene , and Vinyl Chloride resulted in all RPD values meeting the RDP criteria

Modeling annual benzene, toluene, NO2, and soot concentrations on the basis of road traffic characteristics

International Nuclear Information System (INIS)

Carr, David; Ehrenstein, Ondine von; Weiland, Stephan; Wagner, Claudia; Wellie, Oliver; Nicolai, Thomas; Mutius, Erika von

2002-01-01

The investigation of potential adverse health effects of urban traffic-related air pollution is hampered by difficulties encountered with exposure assessment. Usually public measuring sites are few and thereby do not adequately describe spatial variation of pollutant levels over an urban area. In turn, individual monitoring of pollution exposure among study subjects is laborious and expensive. We therefore investigated whether traffic characteristics can be used to adequately predict benzene, NO 2 , and soot concentrations at individual addresses of study subjects in the city area of Munich, Germany. For all road segments with expected traffic volumes of at least 4000 vehicles a day (n=1840), all vehicles were counted manually or a single weekday in 1995. The proportion of vehicles in 'stop-go' mode, n estimate of traffic jam, was determined. Furthermore, annual concentrations of benzene, NO 2 , and soot from 18 high-concentration sites means: 8.7, 65.8, and 12.9 μg/m 3 , respectively) and from 16 school sites with moderate concentrations (means: 2.6, 32.2, and 5.7 μg/m 3 , respectively) were measured from 1996 to 1998. Statistical analysis of the data was performed using components of two different statistical models recently used to predict air pollution levels in comparable settings. Two traffic characteristics, traffic volume and traffic jam percentage, adequately described air pollutant concentrations (R 2 : 0.76-0.80, P=0.0001). This study shows that air pollutant concentrations can be accurately predicted by two traffic characteristics and that these models compare favorably with other more complex models in the literature

Analysis of chemical contamination within a canal in a Mexican border colonia

Energy Technology Data Exchange (ETDEWEB)

Owens, Janel E. [Department of Chemistry and Biochemistry, Southwestern University, Georgetown, TX 78626 (United States); Niemeyer, Emily D. [Department of Chemistry and Biochemistry, Southwestern University, Georgetown, TX 78626 (United States)]. E-mail: niemeyee@southwestern.edu

2006-04-15

This study examines urban pollution within Derechos Humanos, a colonia popular in Matamoros, Tamaulipas, Mexico. General water quality indicators (coliform bacteria, total dissolved solids, ecologically relevant cations and anions), heavy metals (copper, lead, nickel, zinc, iron and cadmium), and volatile organic compounds (benzene, toluene, ethylbenzene, styrene, and dichlorobenzene and xylene isomers) were quantified within a wastewater canal running adjacent to the community. Water samples were collected at multiple sites along the banks of the canal and evidence of anthropogenic emissions existed at each sampling location. Sample site 2, approximately 10 m upstream of the colonia, contained both the widest range of hazardous pollutants and the greatest number exceeding US Environmental Protection Agency surface water standards. At each sampling location, high concentrations of total coliform (>10{sup 4} colonies/100 mL sample), lead (ranging from 0.05 to 0.40 mg/L), nickel (levels from 0.21 to 1.45 mg/L), and benzene (up to 9.80 mg/L) were noted. - This study quantifies widespread industrial and urban contamination within a canal located in a colonia (unplanned community) in Matamoros, Tamaulipas on the US-Mexico border.

Thermal decomposition of foundry resins: A determination of organic products by thermogravimetry–gas chromatography–mass spectrometry (TG–GC–MS

Directory of Open Access Journals (Sweden)

A. Kmita

2018-03-01

Full Text Available The article presents the results of research on thermal decomposition of Ester-Cured Alkaline Phenolic No-Bake (ALPHASET binders used in molding technology. In the ALPHASET system phenol-formaldehyde resin of resole type is cured with a liquid mixture of esters. Under the influence of the molten metal the thermal decomposition of the binder follows, resulting in the evolution of gases, often harmful, e.g. from benzene, toluene, ethylbenzene and xylenes (BTEX or Polycyclic Aromatic Hydrocarbon (PAH groups. The identification of gases evolved during the pyrolysis of the binders was carried out and their decomposition temperatures were determined using the Thermogravimetry–Gas Chromatography–Mass Spectrometry (TG–GC–MS technique. The tests were subjected to two types of binders from different manufacturers. Among the products of pyrolysis there have been identified mainly benzene and its derivatives, and phenol and its derivatives. Compounds identified in pyrolytic gas are largely considered to be harmful to humans and the environment (some of the compounds are carcinogenic and mutagenic. The presented results of the TG–GC–MS measurements show that the applied analytic methods are feasible to perform a qualitative and also quantitative characterization of the binder samples.

Analysis of chemical contamination within a canal in a Mexican border colonia

International Nuclear Information System (INIS)

Owens, Janel E.; Niemeyer, Emily D.

2006-01-01

This study examines urban pollution within Derechos Humanos, a colonia popular in Matamoros, Tamaulipas, Mexico. General water quality indicators (coliform bacteria, total dissolved solids, ecologically relevant cations and anions), heavy metals (copper, lead, nickel, zinc, iron and cadmium), and volatile organic compounds (benzene, toluene, ethylbenzene, styrene, and dichlorobenzene and xylene isomers) were quantified within a wastewater canal running adjacent to the community. Water samples were collected at multiple sites along the banks of the canal and evidence of anthropogenic emissions existed at each sampling location. Sample site 2, approximately 10 m upstream of the colonia, contained both the widest range of hazardous pollutants and the greatest number exceeding US Environmental Protection Agency surface water standards. At each sampling location, high concentrations of total coliform (>10 4 colonies/100 mL sample), lead (ranging from 0.05 to 0.40 mg/L), nickel (levels from 0.21 to 1.45 mg/L), and benzene (up to 9.80 mg/L) were noted. - This study quantifies widespread industrial and urban contamination within a canal located in a colonia (unplanned community) in Matamoros, Tamaulipas on the US-Mexico border

Chromatographic Determination of Toluene and its Metabolites in Urine for Toluene Exposure - A Review

International Nuclear Information System (INIS)

Mohamad Raizul Zinalibdin; Abdul Rahim Yacob; Mohd Marsin Sanagi

2016-01-01

The determinations of toluene and their metabolites in biological samples such as urine and blood allow the estimation of the degree of exposure to this chemical. Chromatographic methods and preliminary methods are now universally employed for this purpose. Preliminary color test methods are well established for qualitative determination of toluene and its metabolites. Mobile test kits using color test methods are a vast tool for screening urine samples but chromatographic methods are still needed for confirmation and quantitative analysis. Gas chromatography (GC) methods are well-adapted for the determination of toluene metabolite in urine, but these methods often require several pretreatment steps. Meanwhile, high performance liquid chromatography (HPLC) is becoming a powerful tool for the accurate and easy determination of toluene metabolites considering its decisive advantages for routine monitoring. Furthermore, recent development in HPLC could widen the usefulness of this method to solve the most complex analytical problems that could be encountered during the measurement. (author)

Remediation of Groundwater Polluted by Aromatic Compounds by Means of Adsorption

Directory of Open Access Journals (Sweden)

Silvana Canzano

2014-07-01

Full Text Available In this work, an experimental and modeling analysis of the adsorption of four aromatic compounds (i.e., toluene, naphthalene, o-xylene and ethylbenzene onto a commercial activated carbon is carried out. The aim is to assess the suitability of the adsorption process for the treatment of polluted groundwater, also when a multiple contamination is detected. Batch adsorption tests from simulated polluted groundwater are performed in single-compound systems and in two binary systems (i.e., toluene + naphthalene and o-xylene + ethylbenzene, at constant temperature (20 °C and pH (7. Experimental results in single-compound systems reveal that all of the analytes are significantly adsorbed on the tested activated carbon. In particular, toluene and naphthalene adsorption capacities are the highest and of similar value, while for o-xylene and ethylbenzene, the performances are lower. The adsorption of these compounds seems to be influenced by a combined effect of several parameters, such as hydrophobicity, molecule size, structure of the molecule, etc. Experimental results in binary systems show a different behavior of the two systems, which confirms their complexity and explains the interest in these complex adsorption systems. In particular, toluene and naphthalene are mutually competitive, while in the case of o-xylene + ethylbenzene, only the former undergoes competitive effects. The analysis of the entire experimental data set is integrated with a dedicated modeling analysis using the extended Langmuir model. For both single-compound and binary systems, this model provides acceptable results, in particular for low equilibrium concentrations, like those more commonly found in groundwater, and for the compounds involved in adsorptive competitive effects.

Evaluation of the performance of a passive sampler in the monitoring of benzene and other volatile aromatic compounds in urban and indoor sites

International Nuclear Information System (INIS)

Bertoni, G.; Tappa, R.; Allegrini, I.

1999-01-01

Laboratory and field tests have been performed on a new passive device, properly designed for the collection of volatile organic compounds from ambient air on an active charcoal layer. Tests performed in order to determine accuracy and precision, response linearity and employment limits show that this device may be helpful in long and medium-time determinations of BTX (benzene, toluene and xylenes) in the atmosphere. The sampler is optimised for a four weeks sampling in open air [it

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

Science.gov (United States)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby

2016-07-01

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

Energy Technology Data Exchange (ETDEWEB)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby, E-mail: bka.ism@gmail.com [Atomic and Molecular Physics Lab, Department of Applied Physics, Indian School of Mines, Dhanbad (India)

2016-07-21

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

[Exposure to benzene and hematologic changes in workers at the Ina-Oki Drnisplast factory in Drnis].

Science.gov (United States)

Mikulandra, O; Cala, D; Marković, V; Zorić, A

1993-12-01

In the summer of 1984 workers in the "INA-OKI Drnisplast" factory frequently complained about headaches, weight loss and irregular menstrual cycles. According to the factory engineers that might have been due to an altered composition of the paints and glues that were used in the manufacturing process that year. Those had been found to lack specifications of chemical composition. Experts from the Institute for the Safety at Work from Zagreb were called in to perform measurements of organic solvents content in the workroom air. Benzene concentrations were found to be up to five times higher than the maximum permissible levels, those of toluene up to three times and of cyclohexane up to ten times higher. The polluted part of the factory was closed down, changes were introduced into the working process (use of paints was stopped, only glues without benzene content were allowed and proper ventilation was installed) and all the workers, twenty in all, received medical treatment. After three months the working process was resumed. In 1989 all the twenty workers underwent a control medical examination. All showed signs of recovery, both objective and subjective. Their blood tests values were within normal range. All the workers continued working, save one who retired in 1988 upon recommendation of a disability commission. The cause of disablement was occupational disease--benzene poisoning. On the basis of this experience emphasis is placed on the importance, in working with benzene, of complying with the Legislation on working capacity assessment for jobs requiring special working conditions and with the Safety at work act.

Benzene: questions and answers

International Nuclear Information System (INIS)

1999-01-01

This information booklet is intended to inform residents near natural gas dehydration facilities about benzene and its levels in the atmosphere. It was issued following the federal government's decision to place benzene on its Priority Substances List and to require industry to establish means for reducing benzene emissions from natural gas dehydrators and to inform residents about benzene emissions from glycol dehydration facilities. Accordingly, the booklet explains what benzene is (a colourless flammable liquid component of hydrocarbons) how it gets into the air (during gasoline refining, vehicle refueling and the production of steel and petrochemicals), the associated health hazards (a recognized carcinogen, causing an increased incidence of leukemia in concentrations of 100 parts per million), defines a glycol dehydrator (a facility built at or near some natural gas fields for the removal of water from the natural gas to prevent corrosion and freezing of pipelines), and enumerates the steps that are being taken to reduce benzene levels in the air (benzene levels in gasoline have been reduced, along with benzene emissions from petrochemical plants, refineries, steel plants and glycol dehydrators by 54 per cent to date; this will rise to 90 per cent by 2005). In addition to these actions, industry plans call for all existing glycol dehydrators within 750 metres of any permanent residence to be limited to benzene emissions of no more than three tonnes per year before 2001; new glycol dehydrators after that date will be expected to have benzene emissions reduced to the lowest level that can be practically achieved

Ionic liquid screening for ethylbenzene/styrene separation by extractive distillation

NARCIS (Netherlands)

Jongmans, M.T.G.; Schuur, B.; Haan, de A.B.

2011-01-01

The separation of ethylbenzene from styrene by distillation is very energy-intensive, because of the low relative volatility (1.3–1.4). Extractive distillation is a promising alternative to separate the close boiling mixture, in which the solvent selection is crucial for the process feasibility. In

Primary atmospheric oxidation mechanism for toluene.

Science.gov (United States)

Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

2009-01-08

The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere.

Synthesis of Nitrogen-Doped Mesoporous Carbon for the Catalytic Oxidation of Ethylbenzene

Science.gov (United States)

Wang, Ruicong; Yu, Yifeng; Zhang, Yue; Lv, Haijun; Chen, Aibing

2017-06-01

Nitrogen-doped ordered mesoporous carbon (NOMC) was fabricated via a simple hard-template method by functionalized ionic liquids as carbon and nitrogen source, SBA-15 as a hard-template. The obtained NOMC materials have a high nitrogen content of 5.55 %, a high surface area of 446.2 m2 g-1, and an excellent performance in catalysing oxidation of ethylbenzene. The conversion rate of ethylbenzene can be up to 84.5% and the yield of acetophenone can be up to 69.9%, the results indicated that the NOMC materials have a faster catalytic rate and a higher production of acetophenone than catalyst-free and CMK-3, due to their uniform pore size, high surface area and rich active sites in the carbon pore walls.

Inhibition of cardiac sodium currents by toluene exposure

Science.gov (United States)

Cruz, Silvia L; Orta-Salazar, Gerardo; Gauthereau, Marcia Y; Millan-Perez Peña, Lourdes; Salinas-Stefanón, Eduardo M

2003-01-01

Toluene is an industrial solvent widely used as a drug of abuse, which can produce sudden sniffing death due to cardiac arrhythmias. In this paper, we tested the hypothesis that toluene inhibits cardiac sodium channels in Xenopus laevis oocytes transfected with Nav1.5 cDNA and in isolated rat ventricular myocytes. In oocytes, toluene inhibited sodium currents (INa+) in a concentration-dependent manner, with an IC50 of 274 μM (confidence limits: 141–407μM). The inhibition was complete, voltage-independent, and slowly reversible. Toluene had no effect on: (i) the shape of the I–V curves; (ii) the reversal potential of Na+; and (iii) the steady-state inactivation. The slow recovery time constant from inactivation of INa+ decreased with toluene exposure, while the fast recovery time constant remained unchanged. Block of INa+ by toluene was use- and frequency-dependent. In rat cardiac myocytes, 300 μM toluene inhibited the sodium current (INa+) by 62%; this inhibition was voltage independent. These results suggest that toluene binds to cardiac Na+ channels in the open state and unbinds either when channels move between inactivated states or from an inactivated to a closed state. The use- and frequency-dependent block of INa+ by toluene might be responsible, at least in part, for its arrhythmogenic effect. PMID:14534149

Rates of BTEX Biodegradation under Nitrate Reducing Conditions in Wetland Sediments Impacted by Contaminated Groundwater

Science.gov (United States)

Olson, L. K.; McGuire, J. T.; Cozzarelli, I.; Smith, E. W.; Kneeshaw, T.

2010-12-01

Biodegradation rates are often controlled by dynamic interactions that occur at mixing interfaces between water masses of differing redox state. This study seeks to understand the controls on rates of BTEX (benzene, toluene, ethylbenzene and m,p,o-xylenes) degradation at a mixing interface by using in-situ experiments to simulate contaminated aquifer water containing nitrate discharging to a methanogenic wetland. BTEX biodegradation was evaluated during “dry” conditions (2009) and “wet” conditions (2010) in a shallow wetland near Bemidji, MN using innovative in-situ microcosms (ISMs) to measure rates of change over 8 weeks (2009) and 9 weeks (2010). ISM samplers contained an inner chamber filled with wetland sediments that were allowed to incubate for 2 weeks. This chamber was then closed to the surrounding environment and amended with test solution composed of contaminated groundwater augmented with tracer (bromide), nitrate and BTEX spike. Analysis of ISM sediments suggests that nitrate reduction and biodegradation rates are a function of both mineralogical and microbiological controls. Loss of nitrate, interpreted as nitrate reduction, was observed in both the dry and wet years with reduction slightly faster in the dry year (2.21mg/L/day versus 1.59 mg/L/day). Nitrate reduction was likely coupled to oxidation of various electron donors present in the system, including not only BTEX but also naturally occurring labile organic matter (ex. acetate) and inorganic electron donors (ex. Fe2+). BTEX degradation rates were considerably higher during the “wet” year than the “dry” year, with the fastest rates occurring immediately following test solution additions. For example, in the first 2 days of the “wet” ISM experiments degradation rates were 57.97ug/L/day for Benzene, 73.24ug/L/day for Toluene, 12.37ug/L/day for Ethyl Benzene and 85.61ug/L/day for Xylene compared to an ISM from the dry year which had slower degradation rates of 2.83ug/L/day for

Recent Development of Catalysts for Removal of Volatile Organic Compounds in Flue Gas by Combustion: A Review

Directory of Open Access Journals (Sweden)

Marco Tomatis

2016-01-01

Full Text Available Volatile organic compounds (VOCs emitted from anthropogenic sources pose direct and indirect hazards to both atmospheric environment and human health due to their contribution to the formation of photochemical smog and potential toxicity including carcinogenicity. Therefore, to abate VOCs emission, the catalytic oxidation process has been extensively studied in laboratories and widely applied in various industries. This report is mainly focused on the benzene, toluene, ethylbenzene, and xylene (BTEX with additional discussion about chlorinated VOCs. This review covers the recent developments in catalytic combustion of VOCs over noble metal catalysts, nonnoble metal catalysts, perovskite catalysts, spinel catalysts, and dual functional adsorbent-catalysts. In addition, the effects of supports, coke formation, and water effects have also been discussed. To develop efficient and cost-effective catalysts for VOCs removal, further research in catalytic oxidation might need to be carried out to strengthen the understanding of catalytic mechanisms involved.

Catalytic Reforming of Lignin-Derived Bio-Oil Over a Nanoporous Molecular Sieve Silicoaluminophosphate-11.

Science.gov (United States)

Park, Y K; Kang, Hyeon Koo; Jang, Hansaem; Suh, Dong Jin; Park, Sung Hoon

2016-05-01

Catalytic pyrolysis of lignin, a major constituent of biomass, was performed. A nanoporous molecular sieve silicoaluminophosphate-11 (SAPO-11) was selected as catalyst. Thermogravimetric analysis showed that 500 degrees C was the optimal pyrolysis temperature. Pyrolyzer-gas chromatography/mass spectroscopy was used to investigate the pyrolysis product distribution. Production of phenolics, the dominant product from the pyrolysis of lignin, was promoted by the increase in the catalyst dose. In particular, low-molecular-mass phenolics were produced more over SAPO-11, while high-molecular-mass phenolics and double-bond-containing phenolics were produced less. The fraction of aromatic compounds, including benzene, toluene, xylene, and ethylbenzene, was also increased by catalytic reforming. The catalytic effects were more pronounced when the catalyst/biomass ratio was increased. The enhanced production of aromatic compounds by an acidic catalyst obtained in this study is in good agreement with the results of previous studies.

MTBE and aromatic hydrocarbons in North Carolina stormwater runoff.

Science.gov (United States)

Borden, Robert C; Black, David C; McBlief, Kathleen V

2002-01-01

A total of 249 stormwater samples were collected from 46 different sampling locations in North Carolina over an approximate 1-year period and analyzed to identify land use types where fuel oxygenates and aromatic hydrocarbons may be present in higher concentrations and at greater frequency. Samples were analyzed by gas chromatography-mass spectrometry in ion selective mode to achieve a quantitation limit of 0.05 microg/l. m-,p-Xylene and toluene were detected in over half of all samples analyzed, followed by MTBE: o-xylene: 1,3,5-trimethylbenzene: ethylbenzene; and 1,2,4-trimethylbenzene. Benzene, DIPE, TAME and 1,2,3-trimethylbenzene were detected in runoff from a gas station or discharge of contaminated groundwater from a former leaking underground storage tank. For all of the aromatic hydrocarbons, the maximum observed contaminant concentrations were over an order of magnitude lower than current drinking water standards.

Distribution of Organic Compounds from Municipal Solid Waste in the Groundwater Downgradient of a Landfill (Grindsted, Denmark)

DEFF Research Database (Denmark)

Rügge, Kirsten; Bjerg, Poul Løgstrup; Christensen, Thomas Højlund

1995-01-01

, and xylenes as dominating. No pesticides were identified, but some phenoxy acids, which could be metabolites of known pesticides, were found. In a distance of approximately 60 m from the landfill, most of the specific organic compounds were no longer detectable. Since dilution and sorption apparently cannot......The distribution of organic compounds in the leachate plume downgradient of the Grindsted Landfill was mapped along two 300 m long transects (285 groundwater samples). At the border of the landfill, elevated concentrations of dissolved organic matter 30-1 10 mg of C L-' (measured as nonvolatile...... organic carbon, NVOC) were found. In a distance of 130 m downgradient of the landfill, the NVOC had decreased to background level, which is 1-3 mg of C L-l. More than 15 organic compounds were identified in the groundwater at the downgradient border of the landfill with benzene, toluene, ethylbenzene...

76 FR 76259 - National Emissions Standards for Hazardous Air Pollutants: Primary Aluminum Reduction Plants

Science.gov (United States)

2011-12-06

... Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene...). The rule is applicable to facilities with affected sources associated with the production of aluminum... are subject to the requirements of this NESHAP: 14 primary aluminum production plants and one carbon...

Risk factor benzene

Energy Technology Data Exchange (ETDEWEB)

Stobbe, H.

1981-01-01

Nearly one hundred years ago clinical and epidemiological studies have already assigned benzene as a markedly haematotoxic substance. Nowadays benzene is known as an important professional noxa, which is straight off directed against the haematopoietic system, essentially to a dose-time-effect. By this it can be taken as a model also for other noxious substances. Similar solvents often contain so-called 'hidden benzene', that means not declared benzene, so that the consumer doesn't know what dangerous substance are available for his personal use. Impairments caused by benzene mostly are manifested earliest after months, years or for tens of years, and the point is, that these haematopoietic disorders are irreversible disturbances of the haematopoietic stem cell compartment. The consequence of this fact is a deep involvement of the proliferation of the erythro-, mono-, granulo- and thrombopoietic cell lines, mostly with predominance of one of these myeloproliferative cell systems. In the further progression of the impairments due to benzene three different clinical pictures can be observed: the aplastic bone marrow syndrome (i.e. aplastic anemia), the haematopoietic dysplasia (i.e. preleukemia) and the acute leukemias (with the subtypes erythroleukosis, myeloblastic-promyelocytic or myelomonocytic from respectively). Also the transition from one clinical picture to another is possible.

Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei

International Nuclear Information System (INIS)

Sabourin, P.J.; Sun, J.D.; MacGregor, J.T.; Wehr, C.M.; Birnbaum, L.S.; Lucier, G.; Henderson, R.F.

1990-01-01

Metabolism of benzene is thought to be necessary to produce the toxic effects, including carcinogenicity, associated with benzene exposure. To extrapolate from the results of rodent studies to potential health risks in man, one must know how benzene metabolism is affected by species, dose, dose rate, and repeated versus single exposures. The purpose of our studies was to determine the effect of repeated inhalation exposures on the metabolism of [14C]benzene by rodents. Benzene metabolism was assessed by characterizing and quantitating urinary metabolites, and by quantitating 14C bound to hemoglobin and micronuclei induction. F344/N rats and B6C3F1 mice were exposed, nose-only, to 600 ppm benzene or to air (control) for 6 hr/day, 5 days/week for 3 weeks. On the last day, both benzene-pretreated and control animals were exposed to 600 ppm, 14C-labeled benzene for 6 hr. Individual benzene metabolites in urine collected for 24 hr after the exposure were analyzed. There was a significant decrease in the respiratory rate of mice (but not rats) pretreated with benzene which resulted in lower levels of urinary [14C]benzene metabolites. The analyses indicated that the only effects of benzene pretreatment on the metabolite profile in rat or mouse urine were a slight shift from glucuronidation to sulfation in mice and a shift from sulfation to glucuronidation in rats. Benzene pretreatment also had no effect, in either species, on formation of [14C]benzene-derived hemoglobin adducts. Mice and rats had similar levels of hemoglobin adduct binding, despite the higher metabolism of benzene by mice. This indicates that hemoglobin adduct formation occurs with higher efficiency in rats. After 1 week of exposure to 600 ppm benzene, the frequency of micronucleated, polychromatic erythrocytes (PCEs) in mice was significantly increased

Tracer kinetic investigations on isomerization and synthesis of /sup 8/C-aromates. II. Isomerization of ethylbenzene by means of heterogeneous catalysts

Energy Technology Data Exchange (ETDEWEB)

Dermietzel, J; Roesseler, M; Jockisch, W; Wienhold, C [Akademie der Wissenschaften der DDR, Leipzig. Zentralinstitut fuer Isotopen- und Strahlenforschung; Franke, H; Klempin, J; Barz, H J [VEB Petrolchemisches Kombinat Schwedt (German Democratic Republic)

1978-01-01

The mechanism of ethylbenzene isomerization on Pt/Al/sub 2/O/sub 3/ catalysts by means of /sup 14/C labelled compounds has been investigated, measuring the isotope distribution between ring and alkyl carbon atoms. The results suggest that ethylbenzene isomerizes via structure rearrangement involving ring carbon atoms. A similar mechanism takes place in xylene isomerization under increased hydrogen partial pressure, while under normal pressure 1,2-methyl group shifting is dominating. All three xylenes are formed from ethylbenzene by parallel reactions.

Liquid-liquid equilibria for binary and ternary systems containing glycols, aromatic hydrocarbons, and water: Experimental measurements and modeling with the CPA EoS

DEFF Research Database (Denmark)

Folas, Georgios; Kontogeorgis, Georgios; Michelsen, Michael Locht

2006-01-01

Liquid-liquid equilibrium data of four binary glycol + aromatic hydrocarbon systems and three ternary systems containing water have been measured at atmospheric pressure. The measured systems are monoethylene glycol (MEG) + benzene or toluene, triethylene glycol (TEG) + benzene or toluene, MEG...... + water + benzene, MEG + water + toluene, and TEG + water + toluene. The binary systems are correlated with the Cubic-Plus-Association (CPA) equation of state while the ternary systems are predicted from interaction parameters obtained from the binary systems. Very satisfactory liquid-liquid equilibrium...... correlations are obtained for the binary systems using temperature-independent interaction parameters, while adequate predictions are achieved for multicomponent water + glycol + aromatic hydrocarbons systems when accounting for the solvation between the aromatic hydrocarbons and glycols or water....

Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites

KAUST Repository

Tope, Balkrishna B.

2011-11-01

Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.

Solvent and polymer concentration effects on the surface morphology evolution of immiscible polystyrene/poly(methyl methacrylate) blends

International Nuclear Information System (INIS)

Cui Liang; Ding Yan; Li Xue; Wang Zhe; Han Yanchun

2006-01-01

The effects of solvent nature on the surface topographies of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend films spin-coated onto the silicon wafer were investigated. Four different solvents, such as ethylbenzene, toluene, tetrahydrofuran and dichloromethane, were chosen. They are better solvents for PS than that for PMMA. When dichloromethane, tetrahydrofuran and toluene were used, PMMA-rich phase domains protruded from the background of PS. When ethylbenzene was used, PS-rich phase domains elevated on the average height of PMMA-rich phase domains. In addition, continuous pits, networks and isolated droplets consisted of PS formed on the blend film surfaces with the decrease of polymer concentrations. The mechanism of the surface morphology evolution was discussed in detail

Molecular Transporters for Desalination Applications

Science.gov (United States)

2014-08-02

products of fructose decomposition. Note that only toluene, ethylbenzene , styrene, indene, and graphite reactions produce graphitic carbon. that... Ethylbenzene Styrene Indene Graphite Table 4: Calculated Gibbs’ free energies of formation for all non -oxygen-containing products of fructose...PyBA in order to compare graphitic carbon production . It should be noted at this point that CNT growth uses a transition metal catalyst to form

Biodegradation and growth characteristics of a toluene-degrading ...

African Journals Online (AJOL)

A toluene-degrading strain was isolated from active sludge in this study. Both growth characteristic and the performance to degrade toluene by the strain in batch culture mode were evaluated. Results showed that the isolated strain presented a good ability to remove toluene with the maximum removal efficiency of 93.8%.

The Structure of Ethylbenzene, Styrene and Phenylacetylene Determined by Total Neutron Scattering.

Science.gov (United States)

Szala-Bilnik, Joanna; Falkowska, Marta; Bowron, Daniel T; Hardacre, Christopher; Youngs, Tristan G A

2017-09-20

Organic solvents such as phenylacetylene, styrene and ethylbenzene are widely used in industrial processes, especially in the production of rubber or thermoplastics. Despite their important applications detailed knowledge about their structure is limited. In this paper the structures of these three aromatic solvents were investigated using neutron diffraction. The results show that many of their structural characteristics are similar, although the structure of phenylacetylene is more ordered and has a smaller solvation sphere than either ethylbenzene or styrene. Two regions within the first coordination sphere, in which the surrounding molecules show different preferable orientations with respect to the central molecule, were found for each liquid. Additionally, the localisation of the aliphatic chains reveals that they tend to favour closer interactions with each other than to the aromatic rings of the adjacent molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intrinsic bioremediation of petroleum hydrocarbons in a gas condensate-contaminated aquifer

International Nuclear Information System (INIS)

Gieg, L.M.; McInerney; Tanner, R.S.; Harris, S.H. Jr.; Sublette, K.L.; Suflita, J.M.; Kolhatkar, R.V.

1999-01-01

A study was designed to determine if the intrinsic bioremediation of gas condensate hydrocarbons represented an important fate process in a shallow aquifer underlying a natural gas production site. For over 4 yr, changes in the groundwater, sediment, and vadose zone chemistry in the contaminated portion of the aquifer were interpreted relative to a background zone. Changes included decreased dissolved oxygen and sulfate levels and increased alkalinity, Fe(II), and methane concentrations in the contaminated groundwater, suggesting that aerobic heterotrophic respiration depleted oxygen reserves leaving anaerobic conditions in the hydrocarbon-impacted subsurface. Dissolved hydrogen levels in the contaminated groundwater indicated that sulfate reduction and methanogenesis were predominant biological processes, corroborating the geochemical findings. Furthermore, 10--1000-fold higher numbers of sulfate reducers and methanogens were enumerated in the contaminated sediment relative to background. Putative metabolites were also detected in the contaminated groundwater, including methylbenzylsuccinic acid, a signature intermediate of anaerobic xylene decay. Laboratory incubations showed that benzene, toluene, ethylbenzene, and each of the xylene isomers were biodegraded under sulfate-reducing conditions as was toluene under methanogenic conditions. These results coupled with a decrease in hydrocarbon concentrations in contaminated sediment confirm that intrinsic bioremediation contributes to the attenuation of hydrocarbons in this aquifer

Organic aerosol formation during the atmospheric degradation of toluene.

Science.gov (United States)

Hurley, M D; Sokolov, O; Wallington, T J; Takekawa, H; Karasawa, M; Klotz, B; Barnes, I; Becker, K H

2001-04-01

Organic aerosol formation during the atmospheric oxidation of toluene was investigated using smog chamber systems. Toluene oxidation was initiated by the UV irradiation of either toluene/air/NOx or toluene/air/CH3ONO/NO mixtures. Aerosol formation was monitored using scanning mobility particle sizers and toluene loss was monitored by in-situ FTIR spectroscopy or GC-FID techniques. The experimental results show that the reaction of OH radicals, NO3 radicals and/or ozone with the first generation products of toluene oxidation are sources of organic aerosol during the atmospheric oxidation of toluene. The aerosol results fall into two groups, aerosol formed in the absence and presence of ozone. An analytical expression for aerosol formation is developed and values are obtained for the yield of the aerosol species. In the absence of ozone the aerosol yield, defined as aerosol formed per unit toluene consumed once a threshold for aerosol formation has been exceeded, is 0.075 +/- 0.004. In the presence of ozone the aerosol yield is 0.108 +/- 0.004. This work provides experimental evidence and a simple theory confirming the formation of aerosol from secondary reactions.

Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

Directory of Open Access Journals (Sweden)

Zhengjun Zhang

2011-12-01

Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

Advances in Biodegradation of Multiple Volatile Organic Compounds

Science.gov (United States)

Zhang, M.; Yoshikawa, M.

2017-12-01

Bioremediation of soil and groundwater containing multiple contaminants remains a challenge in environmental science and engineering because complete biodegradation of all components is necessary but very difficult to accomplish in practice. This presentation provides a brief overview on advances in biodegradation of multiple volatile organic compounds (VOCs) including chlorinated ethylenes, benzene, toluene and dichloromethane (DCM). Case studies on aerobic biodegradation of benzene, toluene and DCM, and integrated anaerobic-aerobic biodegradation of 7 contaminants, specifically, tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (cis-DCE), vinyl chloride (VC), DCM, benzene and toluene will be provided. Recent findings based on systematic laboratory experiments indicated that aerobic toluene degradation can be enhanced by co-existence of benzene. Propioniferax, not a known benzene, toluene and DCM degrader can be a key microorganism that involves in biodegradation when the three contaminants co-exist. Integrated anaerobic-aerobic biodegradation is capable of completely degrading the seven VOCs with initial concentrations less than 30 mg/L. Dehalococcoides sp., generally considered sensitive to oxygen, can survive aerobic conditions for at least 28 days, and can be activated during the subsequent anaerobic biodegradation. This presentation may provide a systematic information about biodegradation of multiple VOCs, and a scientific basis for the complete bioremediation of multiple contaminants in situ.

Effect of diluent on extraction of uranyl nitrate from nitric acid solution by tri-n-octylamine

International Nuclear Information System (INIS)

Kojima, Takashi; Ukon, Toshiaki; Fukutomi, Hiroshi

1979-01-01

The distribution ratios in the extraction equilibriums of uranylnitrate from 3 M HNO 3 by tri-n-octylamine (TOA) nitrate salt in nitrobenzene, chlorobenzene, benzene, toluene, cyclohexane, nitrobenzene-benzene and benzene-cylohexane mixtures have been determined in varying the concentrations of uranyl nitrate and TOA nitrate salt. The extraction mechanisms have been discussed in detail based on the law of mass action. It has been concluded that the extractions of uranyl nitrate by TOA nitrate salt in nitrobenzene, 74% nitrobenzene-benzene and 49% nitrobenzene-benzene mixture are represented by the equation TOAHNO 3 (org) + UO 2 2+ (aq) + 2 NO 3 - (aq) = TOAHUO 2 (NO 3 - ) 3 (org), while the extractions of uranyl nitrate by TOA nitrate salt in chlorobenzene, benzene, toluene, cyclohexane, benzene-cyclohexane mixtures and 24% nitrobenzene-benzene mixture are represented by the equation 2 TOAHNO 3 (org) + UO 2 2+ (aq) + 2 NO 3 - (aq) = TOAHUO 2 (NO 3 ) 3 TOAHNO 3 (org). In the latter the extraction equilibrium constants increase in the order of chlorobenzene < benzene < toluene < cyclohexane and with decreasing of the volume fraction of benzene in benzene-cyclohexane mixtures. The effects of diluent have been discussed in detail on the basis of the Hildebrand-Scatchard theory of regular solutions. (author)

Aromaticity of benzene in condensed phases. A case of a benzene-water system

Science.gov (United States)

Zborowski, Krzysztof K.

2014-05-01

A theoretical Density Functional Theory study was performed for a benzene molecule in water cages. Two DFT functionals (B3LYP and BLYP) were employed. The optimized geometries of the studied clusters were used to calculate the aromaticity of benzene in a condensed phase using the aromaticity indices: HOMA, NICS, PDI, and H. The results were compared with aromaticity of a single benzene molecule in the gas phase and in the solvent environment provided by the PCM continuum model. It is argued that high aromaticity of benzene in the gas phase is retained in the water environment.

Problem Definition Studies on Potential Environmental Pollutants. 4. Physical, Chemical, Toxicological, and Biological Properties of Benzene; Toluene; Xylenes; and para-Chlorophenyl Methyl Sulfide, Sulfoxide, and Sulfone

Science.gov (United States)

1976-06-01

microorganisms. The presence of nitro, amino or sulfonic acid groups or halogens on the ring will almost always render benzene and related compounds...benzoquinone --- muconic acid Their later experiments with tea and grape leaf homogenates support this * conclusion. 12 2 Tkhelidze 1 2 3 showed that grape ...of such chemicals as phenol, aniline, cumene, adipic acid , diphenyl, and ethyl- * benzene, each of which is a starting material for other products

Oxidative dehydrogenation of ethylbenzene using nitrous oxide over vanadia-magnesia catalysts

NARCIS (Netherlands)

Shiju, N.R.; Anilkumar, M.; Gokhale, S.P.; Rao, B.S.; Satyanarayana, C.V.V.

2011-01-01

A series of V-Mg-O catalysts with different loadings of vanadia were prepared by the wet impregnation method and the effect of the local structure of these catalysts on the oxidative dehydrogenation of ethylbenzene with N2O was investigated. High styrene selectivity (97%) was obtained at 773 K. The

Preparation of Magnetic Sorbent with Surface Modified by C18for Removal of Selected Organic Pollutants from Aqueous Samples

Science.gov (United States)

Kuráň, Pavel; Pilnaj, Dominik; Ciencialová, Lucie; Pšenička, Martin

2017-12-01

Magnetic sorbents have great potential in environmental applications due to their simple synthesis and separation in magnetic field, usability in heterogeneous systems and low toxicity. Possible syntheses, surface modifications and characteristics were described by Li et al 2013. This type of solid-phase extraction is being successfully used in various fields as health care, microbiology, biotechnologies or sample preconcentration in analytical chemistry. In this preliminary study we report on the preparation and application of magnetically separable sorbent with surface modified by C18 alkyl chain for purification of water contaminated by environmentally hazardous organic compounds. Magnetic cores were co-precipitated from Fe2+ and Fe3+ chlorides in alkalic aqueous solution. Surface of synthetized Fe3O4 was modified with SiO2 by tetraethylorthosilicate to assure physico-chemical stability. Furthermore, Fe3O4/SiO2 complex has been treated by C18 functional group, which provides good affinity towards hydrophobic substances in water. Efficiency of sorption under various conditions has been examined on benzene, toluene, ethylbenzene and xylenes (BTEX), compounds found in petroleum products which contaminate air, soil and groundwater near of store tanks. Sorption kinetics was followed by gas chromatography with mass spectrometry. The preliminary sorption kinetics data and efficiency of BTEX removal point at the possible application of prepared magnetic sorbent for BTEX removal, especially for ethylbenzene and xylenes.

Mutagenic atmospheres resulting from the photooxidation of aromatic hydrocarbon and NOx mixtures

Science.gov (United States)

Riedel, Theran P.; DeMarini, David M.; Zavala, Jose; Warren, Sarah H.; Corse, Eric W.; Offenberg, John H.; Kleindienst, Tadeusz E.; Lewandowski, Michael

2018-04-01

Although many volatile organic compounds (VOCs) are regulated to limit air pollution and the consequent health effects, the photooxidation products generally are not. Thus, we examined the mutagenicity in Salmonella TA100 of photochemical atmospheres generated in a steady-state atmospheric simulation chamber by irradiating mixtures of single aromatic VOCs, NOx, and ammonium sulfate seed aerosol in air. The 10 VOCs examined were benzene; toluene; ethylbenzene; o-, m-, and p-xylene; 1,2,4- and 1,3,5-trimethylbenzene; m-cresol; and naphthalene. Salmonella were exposed at the air-agar interface to the generated atmospheres for 1, 2, 4, 8, or 16 h. Dark-control exposures produced non-mutagenic atmospheres, illustrating that the gas-phase precursor VOCs were not mutagenic at the concentrations tested. Under irradiation, all but m-cresol and naphthalene produced mutagenic atmospheres, with potencies ranging from 2.0 (p-xylene) to 11.4 (ethylbenzene) revertants m3 mgC-1 h-1. The mutagenicity was due exclusively to direct-acting late-generation products of the photooxidation reactions. Gas-phase chemical analysis showed that a number of oxidized organic chemical species enhanced during the irradiated exposure experiments correlated (r ≥ 0.81) with the mutagenic potencies of the atmospheres. Molecular formulas assigned to these species indicated that they likely contained peroxy acid, aldehyde, alcohol, and other functionalities.

Exposure to Particle Matters and Hazardous Volatile Organic Compounds in Selected Hot Spring Hotels in Guangdong, China

Directory of Open Access Journals (Sweden)

Qiusheng He

2016-04-01

Full Text Available In Guangdong province, many hot springs were exploited and developed into popular places for tourist. In addition, hotels have been set up near hot spring sites to attract people, including local citizens, to spend their spare time inside these so-called “spring hotels”. In our study, indoor air quality was investigated in four hot spring hotels in Guangdong province, China. Measured indoor pollutants included CO2, CO, PM10, PM2.5 and Volatile Organic Compounds (VOCs. As the result show, high concentrations of carbon dioxide might be attributed to poor ventilation; and the variations of indoor PM10, PM2.5 concentrations were related to occupants’ activities. Alpha-pinene and toluene were the most common VOC species in the hot spring hotels other than monocyclic aromatic hydrocarbons like Benzene, Toluene, Ethylbenzene and Xylenes (BTEX, which were at medium levels among the reported indoor pollutants. High cancer risk of benzene in the newly decorated rooms should be seriously taken into consideration in the future. Indoor to Outdoor air concentration ratios (I/O for CO2 and VOCs were higher than 1, indicating their strong indoor sources. Negative correlations were found between indoor CO2 and all the other compounds, and VOCs were shown to be significantly correlated (p < 0.01 to each other, including aromatic hydrocarbons and mono-terpenes. For indoor and outdoor air compounds, correlation coefficients among all compounds did not show a significant correlation, which indicated that these pollutants had different sources. Principal components analysis by SPSS showed that indoor materials, inhabitants’ activities and respiration, cleaning products and outdoor sources were the main sources of indoor detected pollutants in hot spring hotels.

Secondary organic aerosol formation through fog processing of VOCs

Science.gov (United States)

Herckes, P.; Hutchings, J. W.

2010-07-01

Volatile Organic Compounds (VOCs) including benzene, toluene, ethylbenzene and xylenes (BTEX) have been determined in highly concentrated amounts (>1 ug/L) in intercepted clouds in northern Arizona (USA). These VOCs are found in concentrations much higher than predicted by partitioning alone. The reactivity of BTEX in the fog/cloud aqueous phase was investigated through laboratory studies. BTEX species showed fast degradation in the aqueous phase in the presence of peroxides and light. Observed half-lives ranged from three and six hours, substantially shorter than the respective gas phase half-lives (several days). The observed reaction rates were on the order of 1 ppb/min but decreased substantially with increasing concentrations of organic matter (TOC). The products of BTEX oxidation reactions were analyzed using HPLC-UV and LCMS. The first generation of products identified included phenol and cresols which correspond to the hydroxyl-addition reaction to benzene and toluene. Upon investigating of multi-generational products, smaller, less volatile species are predominant although a large variety of products is found. Most reaction products have substantially lower vapor pressure and will remain in the particle phase upon droplet evaporation. The SOA generation potential of cloud and fog processing of BTEX was evaluated using simple calculations and showed that in ideal situations these reactions could add up to 9% of the ambient aerosol mass. In more conservative scenarios, the contribution of the processing of BTEX was around 1% of ambient aerosol concentrations. Overall, cloud processing of VOC has the potential to contribute to the atmospheric aerosol mass. However, the contribution will depend upon many factors such as the irradiation, organic matter content in the droplets and droplet lifetime.

Calixarene Langmuir-Blodgett Thin Films For Volatile Organic Compounds

International Nuclear Information System (INIS)

Capan, R.

2010-01-01

Volatile Organic Compounds (VOC's) such as benzene, toluene, chloroform are chemicals that evaporate easily at room temperature and create many health effects on young children, elderly and a person with heightened sensitivity to chemicals. Concentrations of many VOC's are consistently higher indoors (up to ten times higher) than outdoors because many household products (for example paints, varnishes, many cleaning, disinfecting, cosmetic, degreasing, hobby products etc.) contains VOC's. Some effects of VOC's for human beings can be followed as the eye, nose, and throat irritations; headaches, loss of coordination, nausea; damage to liver, kidneys, and central nervous system. These are big incentives for the development of portable, user-friendly VOC's sensors and for the investigation of the sensing properties of new materials to be prepared as a thin film sensing element. Langmuir-Blodgett (LB) ultra-thin film technique allows us to produce monolayer or multilayer organic thin films that can be used as chemical sensing elements.In this work, materials known as the calix[n]arene are investigated for the production of sensing material against several VOC's such as the chloroform, benzene, ethylbenzene and toluene by using LB thin film techniques. UV-visible, Quartz Crystal Microbalance (QCM) system and Surface Plasmon Resonance (SPR) measurement techniques are used to check the quality of the deposition process onto a solid substrate. Surface morphology and sensing properties of the final sensing layers are then studied by Atomic Force Microscopy (AFM) and SPR techniques. Our results indicated that selected calixarene materials are sensitive enough and quite suitable to fabricate a highly ordered, reproducible and uniform LB film that can be used as a very thin sensing layer against VOC's.

Phase equilibrium study of the binary systems (N-hexyl-3-methylpyridinium tosylate ionic liquid + water, or organic solvent)

International Nuclear Information System (INIS)

Domanska, Urszula; Krolikowski, Marek

2011-01-01

Highlights: → Synthesis, DSC, and measurements of phase equilibrium of N-hexyl-3-methylpyridinium tosylate. → Solvents used: water, alcohols, benzene, alkylbenzenes, and aliphatic hydrocarbons. → Correlation with UNIQUAC, Wilson and NRTL models. → Comparison with different tosylate-based ILs. - Abstract: The (solid + liquid) phase equilibrium (SLE) and (liquid + liquid) phase equilibrium (LLE) for the binary systems ionic liquid (IL) N-hexyl-3-methylpyridinium tosylate (p-toluenesulfonate), {([HM 3 Py][TOS] + water, or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or an aromatic hydrocarbon (benzene, toluene, or ethylbenzene, or propylbenzene), or an alkane (n-hexane, n-heptane, n-octane)} have been determined at ambient pressure using a dynamic method. Simple eutectic systems with complete miscibility in the liquid phase were observed for the systems involving water and alcohols. The phase equilibrium diagrams of IL and aromatic or aliphatic hydrocarbons exhibit eutectic systems with immiscibility in the liquid phase with an upper critical solution temperature as for most of the ILs. The correlation of the experimental data has been carried out using the UNIQUAC, Wilson and the non-random two liquid (NRTL) correlation equations. The results reported here have been compared with analogous phase diagrams reported by our group previously for systems containing the tosylate-based ILs.

Evaluation of the efficiency of an experimental biocover to reduce BTEX emissions from landfill biogas.

Science.gov (United States)

Lakhouit, Abderrahim; Schirmer, Waldir N; Johnson, Terry R; Cabana, Hubert; Cabral, Alexandre R

2014-02-01

Landfill emissions include volatile organic compounds (VOCs) and, particularly, benzene, toluene, ethyl-benzene and xylene isomers (collectively called BTEX). The latter are the most common VOCs found in landfill biogas. BTEX affect air quality and may be harmful to human health. In conjunction with a study aiming to evaluate the efficiency of passive methane oxidizing biocovers, a complementary project was developed with the specific goal of evaluating the reduction in VOC emissions due to the installation of a biocover. One of the biocovers constructed at the Saint-Nicéphore (Quebec, Canada) landfill site was instrumented for this purpose. The total BTEX concentration in the raw biogas ranged from 28.7 to 65.4ppmv, and the measured concentration of BTEX in biogas emitted through the biocover ranged from below the limit of detection (BLD) to 2.1ppmv. The other volatile organic compounds (OVOCs) concentration varied from 18.8 to 40.4ppmv and from 0.8 to 1.2ppmv in the raw biogas and in the emitted biogas, respectively. The results obtained showed that the biocover effectiveness ranged from 67% to 100% and from 96% to 97% for BTEX and OVOC, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Remedial technology for contaminated natural gas dehydrator sites

International Nuclear Information System (INIS)

Prosen, B.J.; Korreck, W.M.; Armstrong, J.M.

1991-01-01

Ground water and soil contamination at many of Michigan's oil and gas well sites has been attributed to natural gas dehydration processes. Since water was once thought to be the only by-product from the dehydration process, condensate from the process was discharged directly to the ground for several years. This condensate was later found to contain benzene, toluene, ethyl-benzene, and xylenes (BTEX), and the process of discharging condensate to the ground was stopped. Many oil and gas well sites had become impacted from the process during this time. Although condensate is no longer discharged to the ground, soil and water contamination still remains at many of these sites. In the last few years, the Michigan Department of Natural Resources has targeted over 90 well sites for assessment of contamination associated with gas dehydration. The results of many of these assessments indicate that soil and ground water have been impacted, and the State of Michigan has mandated cleanup of these sites. Remedial technologies which have been used to contain and/or clean up the sites include excavation and product removal, soil venting, purge and treat, and enhanced biodegradation. This paper is a discussion of the technology, implementation, and results from each of these methods

Knitting aromatic polymers for efficient solid-phase microextraction of trace organic pollutants.

Science.gov (United States)

Liu, Shuqin; Hu, Qingkun; Zheng, Juan; Xie, Lijun; Wei, Songbo; Jiang, Ruifen; Zhu, Fang; Liu, Yuan; Ouyang, Gangfeng

2016-06-10

A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas.

Science.gov (United States)

Marrero, Josette E; Townsend-Small, Amy; Lyon, David R; Tsai, Tracy R; Meinardi, Simone; Blake, Donald R

2016-10-04

Oil and natural gas operations have continued to expand and move closer to densely populated areas, contributing to growing public concerns regarding exposure to hazardous air pollutants. During the Barnett Shale Coordinated Campaign in October, 2013, ground-based whole air samples collected downwind of oil and gas sites revealed enhancements in several potentially toxic volatile organic compounds (VOCs) when compared to background values. Molar emissions ratios relative to methane were determined for hexane, benzene, toluene, ethylbenzene, and xylene (BTEX compounds). Using methane leak rates measured from the Picarro mobile flux plane (MFP) system and a Barnett Shale regional methane emissions inventory, the rates of emission of these toxic gases were calculated. Benzene emissions ranged between 51 ± 4 and 60 ± 4 kg h -1 . Hexane, the most abundantly emitted pollutant, ranged from 642 ± 45 to 1070 ± 340 kg h -1 . While observed hydrocarbon enhancements fall below federal workplace standards, results may indicate a link between emissions from oil and natural gas operations and concerns about exposure to hazardous air pollutants. The larger public health risks associated with the production and distribution of natural gas are of particular importance and warrant further investigation, particularly as the use of natural gas increases in the United States and internationally.

Measurement of spatial and temporal variation in volatile hazardous air pollutants in Tacoma, Washington, using a mobile membrane introduction mass spectrometry (MIMS) system.

Science.gov (United States)

Davey, Nicholas G; Fitzpatrick, Cole T E; Etzkorn, Jacob M; Martinsen, Morten; Crampton, Robert S; Onstad, Gretchen D; Larson, Timothy V; Yost, Michael G; Krogh, Erik T; Gilroy, Michael; Himes, Kathy H; Saganić, Erik T; Simpson, Christopher D; Gill, Christopher G

2014-09-19

The objective of this study was to use membrane introduction mass spectrometry (MIMS), implemented on a mobile platform, in order to provide real-time, fine-scale, temporally and spatially resolved measurements of several hazardous air pollutants. This work is important because there is now substantial evidence that fine-scale spatial and temporal variations of air pollutant concentrations are important determinants of exposure to air pollution and adverse health outcomes. The study took place in Tacoma, WA during periods of impaired air quality in the winter and summer of 2008 and 2009. Levels of fine particles were higher in winter compared to summer, and were spatially uniform across the study area. Concentrations of vapor phase pollutants measured by membrane introduction mass spectrometry (MIMS), notably benzene and toluene, had relatively uniform spatial distributions at night, but exhibited substantial spatial variation during the day-daytime levels were up to 3-fold higher at traffic-impacted locations compared to a reference site. Although no direct side-by-side comparison was made between the MIMS system and traditional fixed site monitors, the MIMS system typically reported higher concentrations of specific VOCs, particularly benzene, ethylbenzene and naphthalene, compared to annual average concentrations obtained from SUMA canisters and gas chromatographic analysis at the fixed sites.

Adsorption of BTEX, MTBE and TAME on natural and modified diatomite.

Science.gov (United States)

Aivalioti, Maria; Papoulias, Panagiotis; Kousaiti, Athanasia; Gidarakos, Evangelos

2012-03-15

The removal of BTEX (benzene, toluene, ethyl-benzene and m-,p-,o-xylenes), MTBE (methyl tertiary butyl ether) and TAME (tertiary amyl methyl ether) from aqueous solutions by raw, thermally, chemically and both chemically and thermally treated diatomite was studied, through batch adsorption experiments. In total, 14 different diatomite samples were created and tested. Selected physical characteristics of the adsorbents, such as specific surface area and pore volume distribution, were determined. Matrix and competitive adsorption effects were also explored. It was proved that the diatomite samples were effective in removing BTEX, MTBE and TAME from aqueous solutions, with the sample treated with HCl being the most effective, as far as its adsorption capacity and equilibrium time are concerned. Among the contaminants, BTEX appeared to have the strongest affinity, based on mass uptake by the diatomite samples. Matrix effects were proved to be strong, significantly decreasing the adsorption of the contaminants onto diatomite. The kinetics data proved a closer fit to the pseudo second order model, while the isotherm experimental data were a better fit to the Freundlich model. However, the latter produced values of the isotherm constant 1/n greater than one, indicating unfavorable adsorption. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of ethanol, cimetidine and propranolol on toluene metabolism in man

DEFF Research Database (Denmark)

Døssing, M; Bælum, Jesper; Hansen, S H

1984-01-01

In a climatic exposure chamber four healthy volunteers were exposed to 100ppm toluene, 100ppm toluene + ethanol, 100ppm toluene + cimetidine, and 100ppm toluene + propranolol for 7h each at random over four consecutive days. A control experiment and 3.5h of exposure to 200ppm toluene were also...

Remediation of sandy soils contaminated with hydrocarbons and halogenated hydrocarbons by soil vapour extraction.

Science.gov (United States)

Albergaria, José Tomás; Alvim-Ferraz, Maria da Conceição M; Delerue-Matos, Cristina

2012-08-15

This paper presents the study of the remediation of sandy soils containing six of the most common contaminants (benzene, toluene, ethylbenzene, xylene, trichloroethylene and perchloroethylene) using soil vapour extraction (SVE). The influence of soil water content on the process efficiency was evaluated considering the soil type and the contaminant. For artificially contaminated soils with negligible clay contents and natural organic matter it was concluded that: (i) all the remediation processes presented efficiencies above 92%; (ii) an increase of the soil water content led to a more time-consuming remediation; (iii) longer remediation periods were observed for contaminants with lower vapour pressures and lower water solubilities due to mass transfer limitations. Based on these results an easy and relatively fast procedure was developed for the prediction of the remediation times of real soils; 83% of the remediation times were predicted with relative deviations below 14%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of airborne BTEX exposures during use of lawnmowers and trimmers.

Science.gov (United States)

Avens, Heather J; Maskrey, Joshua R; Insley, Allison L; Unice, Kenneth M; Reid, Rachel C D; Sahmel, Jennifer

2018-02-08

Few studies have evaluated airborne exposures to benzene, toluene, ethylbenzene, and xylenes (BTEX) during operation of two-stroke and four-stroke small engines, such as those in lawn maintenance equipment. Full-shift, 8-hour personal samples were collected during a simulation study to characterize yard maintenance activities including mowing, trimming, and fueling. Short-term, 15-minute personal samples were collected to separately evaluate mowing and trimming exposures. Mean 8-hour time weighted average (TWA) BTEX concentrations were 2.3, 5.8, 0.91, and 4.6 ppb, respectively (n = 2). Mean 15-minute TWA BTEX concentrations were 1.6, 1.8, 0.22, and 1.3 ppb, respectively, during mowing and 1.2, 3.6, 0.68, and 3.3 ppb, respectively, during trimming (n = 3 per task). Measured BTEX concentrations during fueling were 20-110, 61-310, 8-41, and 40-203 ppb, respectively (n = 2, duration 2-3 minutes). These exposure concentrations were well below applicable US occupational exposure limits.

Solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Crittenden, J. C. [Michigan Technological University, Houghton, Michigan (United States); Zhang, Y.; Hand, D. W.; Perram, D. L.; Marchand, E. G.

1996-05-15

A field test of a solar photocatalytic process for detoxification of water was conducted at Tyndall Air Force Base, Florida, where benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were found in the fuel-contaminated groundwater. Platinized titanium dioxide supported on silica gel is packed in tubular photoreactors and used for single-pass operations. Catalyst fouling, destruction inhibition, and water pretreatment are investigated in addition to BTEX destruction. Ionic species were found to be primarily responsible for photocatalyst fouling and destruction inhibition. A simple pretreatment unit was developed for removing turbidity, adding oxidant, and ionic species. By using pretreatment, the reactor system operated efficiently, and no loss in catalyst photoactivity was found during the month-long test. On a rainy day, BTEX compounds of a total influent concentration of more than 2 mg/L were destroyed within 6.5 minutes of empty-bed contact time. Test results with various flow rates, reactor diameters, influent concentrations, solar irradiances, and weather conditions confirm the application potential of the process.

Superfund record of decision (EPA Region 3): Paoli Rail Yard, Paoli, PA. (First remedial action), July 1992. Final report

International Nuclear Information System (INIS)

1992-01-01

The 428-acre Paoli Rail Yard site is a maintenance, storage, and repair facility located north of Paoli in Chester County, Pennsylvania. Soil contamination in and around the car shop is attributed to releases of fuel oil and PCB-laden transformer fluid from rail cars during maintenance and repair activities. In 1985, EPA identified PCB contamination in soil and sediment, and on building surfaces. The rail companies agreed to address site clean-up activities, including erosion, sedimentation, and stormwater characteristics and control, decontamination, soil sampling, excavation of 3,500 cubic yards residential soil, and implementation of worker protection measures. The ROD provides a final remedy for contaminated soil (from the rail yard and residences), sediment, and structures at the Paoli Rail Yard, and contaminated ground water. The primary contaminants of concern affecting the soil, sediment, debris, and ground water are VOCs, including benzene, ethylbenzene, toluene, xylenes; and other organics, including PCBs. The selected remedial action for the site are included

Solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts

International Nuclear Information System (INIS)

Crittenden, J.C.; Zhang, Y.; Hand, D.W.; Perram, D.L.; Marchand, E.G.

1996-01-01

A field test of a solar photocatalytic process for detoxification of water was conducted at Tyndall Air Force Base, Florida, where benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were found in the fuel-contaminated groundwater. Platinized titanium dioxide supported on silica gel is packed in tubular photoreactors and used for single-pass operations. Catalyst fouling, destruction inhibition, and water pretreatment are investigated in addition to BTEX destruction. Ionic species were found to be primarily responsible for photocatalyst fouling and destruction inhibition. A simple pretreatment unit was developed for removing turbidity, adding oxidant, and ionic species. By using pretreatment, the reactor system operated efficiently, and no loss in catalyst photoactivity was found during the month-long test. On a rainy day, BTEX compounds of a total influent concentration of more than 2 mg/L were destroyed within 6.5 minutes of empty-bed contact time. Test results with various flow rates, reactor diameters, influent concentrations, solar irradiances, and weather conditions confirm the application potential of the process

Enhanced photocatalytic degradation of pollutants in petroleum refinery wastewater under mild conditions

International Nuclear Information System (INIS)

Saien, J.; Nejati, H.

2007-01-01

A circulating photocatalytic reactor was used for removing aliphatic and aromatic organic pollutants in refinery wastewater. The TiO 2 added wastewater samples, while saturating with air, were irradiated with an immersed mercury UV lamp (400 W, 200-550 nm). Optimal catalyst concentration, fluid pH and temperature were obtained at amounts of near 100 mg L -1 , 3 and 318 K, respectively. A maximum reduction in chemical oxygen demand of more than 90% was achieved after about 4 h irradiation and hence, 73% after about only 90 min; significant pollutant removal was also achievable in the other conditions. The identification of the organic pollutants, provided by means of a GC/MS and a GC analysis systems, equipped with headspace injection technique, showed that the major compounds were different fractions of petroleum aliphatic hydrocarbons (up to C 10 ) and the well-known aromatic compounds such as benzene, toluene and ethylbenzene. The results showed a high efficiency degradation of all of these pollutants

Enhanced photocatalytic degradation of pollutants in petroleum refinery wastewater under mild conditions

Energy Technology Data Exchange (ETDEWEB)

Saien, J. [Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan 65174 (Iran, Islamic Republic of)], E-mail: saien@basu.ac.ir; Nejati, H. [Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan 65174 (Iran, Islamic Republic of)

2007-09-05

A circulating photocatalytic reactor was used for removing aliphatic and aromatic organic pollutants in refinery wastewater. The TiO{sub 2} added wastewater samples, while saturating with air, were irradiated with an immersed mercury UV lamp (400 W, 200-550 nm). Optimal catalyst concentration, fluid pH and temperature were obtained at amounts of near 100 mg L{sup -1}, 3 and 318 K, respectively. A maximum reduction in chemical oxygen demand of more than 90% was achieved after about 4 h irradiation and hence, 73% after about only 90 min; significant pollutant removal was also achievable in the other conditions. The identification of the organic pollutants, provided by means of a GC/MS and a GC analysis systems, equipped with headspace injection technique, showed that the major compounds were different fractions of petroleum aliphatic hydrocarbons (up to C{sub 10}) and the well-known aromatic compounds such as benzene, toluene and ethylbenzene. The results showed a high efficiency degradation of all of these pollutants.

Design of Batch Distillation Columns Using Short-Cut Method at Constant Reflux

Directory of Open Access Journals (Sweden)

Asteria Narvaez-Garcia

2013-01-01

Full Text Available A short-cut method for batch distillation columns working at constant reflux was applied to solve a problem of four components that needed to be separated and purified to a mole fraction of 0.97 or better. Distillation columns with 10, 20, 30, 40, and 50 theoretical stages were used; reflux ratio was varied between 2 and 20. Three quality indexes were used and compared: Luyben’s capacity factor, total annual cost, and annual profit. The best combinations of theoretical stages and reflux ratio were obtained for each method. It was found that the best combinations always required reflux ratios close to the minimum. Overall, annual profit was the best quality index, while the best combination was a distillation column with 30 stages, and reflux ratio’s of 2.0 for separation of benzene (i, 5.0 for the separation of toluene (ii, and 20 for the separation of ethylbenzene (iii and purification of o-xylene (iv.

In situ radio-frequency heating for soil remediation at a former service station: case study and general aspects

Energy Technology Data Exchange (ETDEWEB)

Huon, G.; Simpson, T.; Maini, G. [Ecologia Environmental Solutions Ltd., Sittingbourne, Kent (United Kingdom); Holzer, F.; Kopinke, F.D.; Roland, U. [Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig (Germany); Will, F. [Total UK, Watford (United Kingdom)

2012-08-15

In situ radio-frequency heating (ISRFH) was successfully applied during remediation of a former petrol station. Using a three-electrode array in combination with extraction wells for soil vapor extraction (SVE), pollution consisting mainly of benzene, toluene, ethylbenzene, xylenes, and mineral oil hydrocarbons (in total about 1100 kg) was eliminated from a chalk soil in the unsaturated zone. Specially designed rod electrodes allowed selective heating of a volume of approximately 480 m{sup 3}, at a defined depth, to a mean temperature of about 50 C. The heating drastically increased the extraction rates. After switching off ISRFH, SVE remained highly efficient for some weeks due to the heat-retaining properties of the soil. Comparison of an optimized regime of ISRFH/SVE with conventional ''cold'' SVE showed a reduction of remediation time by about 80 % while keeping the total energy consumption almost constant. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Evaluation of advanced gas chromatographs for on-site analysis. Final CRADA report for number Y-1295-0374

Energy Technology Data Exchange (ETDEWEB)

Wise, M.B.; Guerin, M.R.; Palausky, A.; Merriweather, R. [Lockheed Martin Energy Research, Oak Ridge, TN (United States); Forsberg, R.E. [Mine Safety Appliances-Baseline Industries, Lyons, CO (United States)

1997-02-21

The EKHO gas chromatography (GC) is being marketed by Mine Safety Appliances as an instrument for on-site environmental analysis and for process applications. This GC utilizes a unique bundled capillary column produced in Russia that provides very fast analysis and a wide linear dynamic range. Oak Ridge National Laboratory (ORNL) has been involved in a CRADA with Mine Safety Appliances in order to evaluate the analytical performance of the EKHO GC and is suitability for on-site environmental applications. Tests that were performed at ORNL included the analysis of air, water, and soil samples for aromatic hydrocarbons including benzene, toluene, xylene, and ethylbenzene (BTEX). These compounds were selected in order to simulate contamination by gasoline and other petroleum fuels. Performance factors that were studied included the instrument detection limits, the linearity, dynamic range, and precision for replicate samples. Other factors that were evaluated include the ease of set-up and operation.

Integrated environmental risk assessment for petroleum-contaminated sites - a North American case study

International Nuclear Information System (INIS)

Chen, Z.; Huang, G.H.; Chakma, A.

1998-01-01

In this study, an integrated risk assessment approach is proposed for evaluating environmental risks derived from petroleum-contaminated sites. The proposed approach is composed of (i) a hydrocarbon spill screening model (HSSM) which is used for simulating immiscible flow of released hydrocarbons in vadose zone, formation of lens in capillary fringe, dissolution of pollutants at water table, and transport of the pollutants to receptors, and (ii) a fuzzy relation analysis (FRA) model which is developed for comprehensively evaluating risks caused by a number of pollutants with different impact characteristics, based on the HSSM results. This hybrid HSSM-FRA approach was applied to a case study for a petroleum-contaminated site in western Canada, where soil and groundwater was contaminated by industrial wastes containing benzene, toluene, ethylbenzene and xylenes (BTEXs). The results suggest that the HSSM-FRA can provide insight into the potential risk to the receptor of concern downward the aquifer and can serve as a basis for further remediation-related decision analysis. (author)

Investigation of carriers of lustrous carbon at high temperatures by infrared spectroscopy (FTIR

Directory of Open Access Journals (Sweden)

S. Eichholz

2010-10-01

Full Text Available Lustrous carbon is very important in processes of iron casting in green sand. Lustrous carbon (pirografit is a microcrystalline carbon form, which evolves from a gaseous phase. In the case of applying additions, generating lustrous carbon, for sands with bentonite, there is always a danger of emitting – due to a high temperature of liquid cast iron and a humidity - compounds hazardous for a human health. There can be: CO, SO2, benzene, toluene, ethylbenzene, xylene (the so-called: BTEX as well as polycyclic aromatic hydrocarbons(PAHs. In order to asses the selected mixtures: bentonite – carrier of lustrous carbon, in which a coal dust fraction was limited, thethermogravimetric analysis and the analysis of evolving gases were performed. Examinations were carried out in the ApplictaionsLaboratory NITZSCH-Gerätebau GmbH ,Selb/Bavaria, Germany. The NETZSCH TG 209 F1 Iris® thermal analyzer coupled to the BRUKER Optics FTIR TENSOR(TM was used to measure.