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1

BTEX [benzene, toluene, ethyl benzene, xylene] control via biofiltration  

Energy Technology Data Exchange (ETDEWEB)

In the use of biofiltration for controlling air pollution problems, the polluted air is conditioned and then passed through a filter, usually ca 1 m thick, composed of a variety of organic and inorganic materials, where naturally occurring and/or inoculated microorganisms break down the offending compounds, releasing clean air plus harmless and odor-free compounds to the atmosphere. One of the main areas of interest for applying biofiltration in North America has been for site remediation of soils contaminated with hydrocarbons, particularly benzene, toluene, ethyl benzene, and xylene (BTEX) associated with gasoline spills. The Ambio Biofiltration biofilter, which is compost-based, has had its first commercial application at a gas station in Quebec, on the end of a soil vapor extraction system. The soil under the station was found to have high BTEX levels, so wells were drilled at the site and a vapor extraction system was installed. Total air flow from the system is ca 50 ft[sup 3]/min, which is easily handled by the Ambio system. The biofilters have removed over 90% of total BTEX (86-98% for individual compounds) and after several months of operation, emission levels are lower than the detection limit of ca 0.5 ppM. Cost of the system is ca $20-30/kg of total BTEX treated. The Ambio unit is compact and has had no problem operating in the middle of one of the coldest winters on record. Infrastructure requirements for the Ambio system are simple and filter life should be in excess of five years. 2 figs.

Pride, C

1994-08-01

2

Formation of ethyl benzene and styrene by side chain methylation of toluene using different zeolite catalysts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The principle aim of this work was to obtain good selectivities of styrene and ethyl benzene by alkylation of toluene with methanol in a single step. In order to achieve this side chain alkylation different alkali metal on HZSM-5, Y and BEA zeolites catalyst were prepared. Different molar ratio of t...

Abdallah, Mohamed Hassen Ahmed

3

Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations  

International Nuclear Information System (INIS)

This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

2004-01-01

4

Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations; Exposition par inhalation au benzene, toluene, ethylbenzene et xylenes (BTEX) dans l'air. Source, mesures et concentrations  

Energy Technology Data Exchange (ETDEWEB)

This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

Del Gratta, F.; Durif, M.; Fagault, Y.; Zdanevitch, I

2004-12-15

5

Evaluating the effects of maternal exposure to benzene, toluene, ethyl benzene, and xylene on oral clefts among offspring in Texas: 1999-2008.  

UK PubMed Central (United Kingdom)

BACKGROUND: There is evidence from previous studies that maternal occupational exposure to hazardous air pollutants (HAPs) is positively associated with oral clefts; however, studies evaluating the association between residential exposure to these toxicants and oral clefts are lacking. Therefore, our goal was to conduct a case-control study examining the association between estimated maternal residential exposure to benzene, toluene, ethyl benzene, and xylene (BTEX) and the risk of oral clefts among offspring. METHODS: Data on 6045 nonsyndromic isolated oral cleft cases (3915 cleft lip with or without cleft palate [CL?±?P] and 2130 nonsyndromic isolated cleft palate [CP] cases) delivered between 1999 and 2008 were obtained from the Texas Birth Defects Registry. The control group was a sample of unaffected live births, frequency matched to cases on year of birth. Census tract-level estimates of annual average exposures were obtained from the U.S. Environmental Protection Agency 2005 Hazardous Air Pollutant Exposure Model (HAPEM5) for each pollutant and assigned to each subject based on maternal residence during pregnancy. Logistic regression was used to assess the relationship between estimated maternal exposure to each pollutant (BTEX) separately and the risk of oral clefts in offspring. RESULTS: High estimated maternal exposure to benzene was not associated with oral clefts, compared with low estimated exposure (CL?±?P adjusted OR?=?0.95; 95% CI?=?0.81?-?1.12; CP adjusted OR?=?0.85; 95% CI?=?0.67?-?1.09). Similar results were seen for the other pollutants. CONCLUSION: In our study, there was no evidence that maternal exposure to environmental levels of BTEX was associated with oral clefts. Birth Defects Research (Part A) 97:532-537, 2013. © 2013 Wiley Periodicals, Inc.

Ramakrishnan A; Lupo PJ; Agopian AJ; Linder SH; Stock TH; Langlois PH; Craft E

2013-08-01

6

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)

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.

K. L. Shivabasappa; P. Nirguna Babu; Y. Jagannadha Rao

2008-01-01

7

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 A (more) lcohol 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.

Shivabasappa, K. L.; Babu, P. Nirguna; Rao, Y. Jagannadha

2008-03-01

8

Ethyl benzene from ethane and benzene  

Energy Technology Data Exchange (ETDEWEB)

A new process to produce ethyl benzene for styrene production by employing a new zeolite catalyst starting with ethane and benzene. The demand for styrene is projected to growth due to new polymer technology under development.

Pogue, R. [Dow Chemical Co., Freeport, TX (United States)

1996-10-01

9

Process for the preparation of ethyl benzene  

Energy Technology Data Exchange (ETDEWEB)

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 300.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered.

Smith, Jr., Lawrence A. (Houston, TX); Arganbright, Robert P. (Houston, TX); Hearn, Dennis (Houston, TX)

1995-01-01

10

Reductive dehalogenation of chlorinated benzenes and toluenes under methanogenic conditions  

Energy Technology Data Exchange (ETDEWEB)

The anaerobic metabolism of chlorinated benzenes and toluenes was evaluated in soil slurry microcosms under methanogenic conditions. A mixture of hexachlorobenzene, pentachlorobenzene, and 1,2,4-trichlorobenzene (TCB) in soil slurries was biotransformed through sequential reductive dechlorination to chlorobenzene (CB). The metabolic pathway for hexachlorobenzene and pentachlorobenzene decay proceeded via 1,2,3,4-tetrachlorobenzene (TTCB) [yields] 1,2,3-TCB + 1,2,4-TCB [yields] 1,2-dichlorobenzene (DCB) + 1,4-DCB [yields] CB. In a mineral salts medium, the CB-adapted soil microorganisms dehalogenated individual 1,2,4,5-TTCB, 1,2,3,4-TTCB, 1,2,3-TCB, and 1,2,4-TCB but not 1,2,3,5-TTCB or 1,3,5-TCB. Similarly, a mixture of 2,3,6-trichlorotoluene (TCT), 2,5-dichlorotoluene (DCT), and 3,4-DCT was reductively dechlorinated in soil slurries to predominantly toluene and small amounts of 2-, 3-, and 4-chlorotoluene (CT). Toluene was further degraded. When tested individually in a mineral salts medium, the CT-adapted soil microorganisms dechlorinated several TCT and DCT isomers. Key metabolic routes for TCTs followed: 2,3,5-TCT [yields] 2,5-DCT [yields] 2-CT [yields] toluene; 2,4,5-TCT [yields] 2,5-DCT + 3,4-DCT [yields] 3-CT + 4-CT [yields] toluene. Among DCTs tested, 2,4-DCT and 3,4-DCT were dechlorinated via the removal of o- and m-chlorine, respectively, to 4-CT and subsequently to toluene via p-chlorine removal. Likewise, 2,5-DCT was dechlorinated via 2-CT to toluene. Evidently, microorganisms capable of removing o-, m-, and p-chlorines are present in the soil system, as reflected by the dechlorination of different isomers of CBs and CTs to CB and toluene, respectively. These findings help clarify the metabolic fate of chlorinated benzenes and toluenes in anaerobic environments.

Ramanand, K.; Balba, M.T. (TreaTek-CRA Company, Grand Island, NY (United States)); Duffy, J. (Occidental Chemical Corporation, Grand Island, NY (United States))

1993-10-01

11

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

Science.gov (United States)

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.

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

2007-01-01

12

Simultaneous removal of ethyl acetate and toluene in air streams using compost-based biofilters.  

UK PubMed Central (United Kingdom)

Biofitration was successfully applied to treat air streams containing a mixture of ethyl acetate and toluene. The experiment was performed by two identical bench-scale biofilters, which were acclimated by ethyl acetate and toluene, respectively. During a 3 month steady-state performance, the two biofilters showed equivalent elimination capacity (EC) for toluene (50 g/m(3) bed/h of pure toluene). However, the biofilter acclimated with ethyl acetate showed a much higher EC for ethyl acetate (400 g/m(3) bed/h of pure ethyl acetate) than that acclimated with toluene (250 g/m(3) bed/h). The concurrent biofiltration of toluene was inhibited by the presence of ethyl acetate. The results also showed that more nitrogen and phosphorus were consumed in the process of the biofiltration of toluene compared with the treatment of ethyl acetate. After the 3 month experiment, the pH of the media treating ethyl acetate dropped from 6.71 to 5.50, whereas the pH of the media treating toluene increased from 6.71 to 7.08.

Liu Y; Quan X; Sun Y; Chen J; Xue D; Chung JS

2002-11-01

13

TCE degradation by toluene/benzene monooxygenase of Pseudomonas aeruginosa JI104 and Escherichia coli recombinant  

Energy Technology Data Exchange (ETDEWEB)

Pseudomonas aeruginosa JI104 incorporates more than three degradation pathways for aromatic compounds such as benzene, toluene, and xylene. A dioxygenase and two monooxygenases were cloned in Escherichia coli XL1-Blue. The dioxygenase yielding cis-toluene dihydrodiol and one of the monooxygenases producing o-cresol from toluene did not exhibit conspicuous activity in trichloroethylene (TCE) oxygenation, although DNA sequencing proved that the former enzyme was an isozyme of toluene dioxygenase of the known TCE decomposer P.putida F1. The other toluene/benzene monooxygenase that could generate o-, m-, and p-cresol simultaneously from toluene showed TCE oxygenation activity resulting in TCE decomposition in E. coli. The activity was inhibited competitively by toluene, ethylbenzene, and o- and m-xylene: their inhibition constants were greater than those of propylbenzene and p-xylene. When the E. coli recombinant harboring the monooxygenase was induced by isopropyl {beta}-D-thiogalactopyranoside (IPTG) and incubated in the absence of toluene, TCE degradation activity decreased during incubation, compared to that with toluene. Toluene probably controlled the lifetime of the enzyme.

Koizumi, Junichi [National Univ. of Yokohama (Japan). Div. of Bioengineering; Kitayama, Atsushi [Univ. of Tokyo (Japan). Dept. of Biochemistry and Biotechnology

1995-12-31

14

Evaluation of exposure biomarkers in offshore workers exposed to low benzene and toluene concentrations.  

UK PubMed Central (United Kingdom)

PURPOSE: Characterize ethylbenzene and xylene air concentrations, and explore the biological exposure markers (urinary t,t-muconic acid (t,t-MA) and unmetabolized toluene) among petroleum workers offshore. Offshore workers have increased health risks due to simultaneous exposures to several hydrocarbons present in crude oil. We discuss the pooled benzene exposure results from our previous and current studies and possible co-exposure interactions. METHODS: BTEX air concentrations were measured during three consecutive 12-h work shifts among 10 tank workers, 15 process operators, and 18 controls. Biological samples were collected pre-shift on the first day of study and post-shift on the third day of the study. RESULTS: The geometric mean exposure over the three work shifts were 0.02 ppm benzene, 0.05 ppm toluene, 0.03 ppm ethylbenzene, and 0.06 ppm xylene. Benzene in air was significantly correlated with unmetabolized benzene in blood (r = 0.69, p < 0.001) and urine (r = 0.64, p < 0.001), but not with urinary t,t-MA (r = 0.27, p = 0.20). Toluene in air was highly correlated with the internal dose of toluene in both blood (r = 0.70, p < 0.001) and urine (r = 0.73, p < 0.001). Co-exposures were present; however, an interaction of metabolism was not likely at these low benzene and toluene exposures. CONCLUSION: Urinary benzene, but not t,t-MA, was a reliable biomarker for benzene at low exposure levels. Urinary toluene was a useful biomarker for toluene exposure. Xylene and ethylbenzene air levels were low. Dermal exposure assessment needs to be performed in future studies among these workers.

Hopf NB; Kirkeleit J; Bråtveit M; Succop P; Talaska G; Moen BE

2012-04-01

15

Biodegradation of methane, benzene, and toluene by a consortium MBT14 enriched from a landfill cover soil.  

UK PubMed Central (United Kingdom)

In this study, landfill cover soil was used as an inoculum source to enrich a methane, benzene, and toluene-degrading consortium MBT14. Under a single substrate, the maximum degradation rates of methane, benzene and toluene were 1.96, 0.15, and 0.77 mmole g-DCW(-1) h(-1), respectively. Although the coexistence of benzene and toluene inhibited the methane degradation rates, the consortium was able to simultaneously degrade methane, benzene and toluene. Methane had an insignificant effect on benzene or toluene degradation. Based on 16S rDNA sequencing analysis, Cupriavidus spp. are dominant in the consortium MBT14. The combined results of this study indicate that the consortium MBT 14 is a promising bioresource for removing CH(4), benzene, and toluene from a variety of environments.

Lee EH; Park H; Cho KS

2013-01-01

16

Biodegradation of methane, benzene, and toluene by a consortium MBT14 enriched from a landfill cover soil.  

Science.gov (United States)

In this study, landfill cover soil was used as an inoculum source to enrich a methane, benzene, and toluene-degrading consortium MBT14. Under a single substrate, the maximum degradation rates of methane, benzene and toluene were 1.96, 0.15, and 0.77 mmole g-DCW(-1) h(-1), respectively. Although the coexistence of benzene and toluene inhibited the methane degradation rates, the consortium was able to simultaneously degrade methane, benzene and toluene. Methane had an insignificant effect on benzene or toluene degradation. Based on 16S rDNA sequencing analysis, Cupriavidus spp. are dominant in the consortium MBT14. The combined results of this study indicate that the consortium MBT 14 is a promising bioresource for removing CH(4), benzene, and toluene from a variety of environments. PMID:23245302

Lee, Eun-Hee; Park, Hyunjung; Cho, Kyung-Suk

2013-01-01

17

Kinetic modeling of benzene and toluene decomposition in air and in flue gas under electron beam irradiation  

International Nuclear Information System (INIS)

Computer simulations of benzene and toluene decomposition in air (79% N2+21% O2) and in flue gas (87% N2+10% O2+3% H2O+160 ppm SO2+80 ppm NO) under electron beam (EB) irradiation were carried out using computer code KINETIC and GEAR method. 285 reactions involving 73 species and 294 reactions involving 78 species were considered for simulation of benzene and toluene decomposition, respectively. Calculation results of benzene and toluene decomposition in air under electron beam agree well with the published experimental results. ·OH radicals play a main role in benzene or toluene decomposition. - Highlights: ? Benzene/toluene decompositions under electron beam irradiation were simulated. ? Computer code KINETIC and GEAR method were used. ? By-products of benzene/toluene decomposition under EB irradiation were predicted.

2012-01-01

18

Toluene and benzene inhalation influences on ventricular arrhythmias in the rat.  

Science.gov (United States)

We have previously found that toluene did not share the capacity of benzene for increasing the arrhythmogenic action of epinephrine in the rat, but appeared to elicit the opposite effect. The present experiments were carried out to verify this observation in rats subjected to more severe ventricular arrhythmias. In animals previously inhaling either air, toluene or benzene and anesthetized with pentobarbital, arrhythmias were produced by coronary ligation or aconitine. In both models, toluene decreased and benzene increased the number of ectopic ventricular beats in the 30 min following induction of arrhythmia. Gas chromatographic measurement of toluene levels in the heart during and after inhalation revealed essentially constant concentrations at the time of arrhythmia evaluation, equivalent to approximately one-third the peak levels observed at the end of inhalation. Although the mechanism of the effect of toluene on arrhythmia could not be ascertained, nonspecific membrane stabilization or central serotonergic stimulation were considered as possible explanations. Since both mechanisms could be operant also in the case of benzene, the opposite effects of the solvents on arrhythmia could not be readily accounted for. PMID:2333062

Magos, G A; Lorenzana-Jiménez, M; Vidrio, H

19

Occupational exposure to benzene, toluene and xylene and the T lymphocyte functions  

Energy Technology Data Exchange (ETDEWEB)

In 72 workers having occupational contact with benzene, toluene or xylene during 31 to 122 months, the T lymphocyte functions were evaluated. Workers after a service of 55-122 months showed a decreased T lymphocyte count without, however, alterations in their functions. No clinical signs of diminished immunological reactivity were noted in the subjects studied. The E rosette test is of importance in the evaluation of early effects on the lymphocyte system of the toxic action of benzene and its homologues.

Moszczynsky, P.; Lisiewicz, J.

1984-01-01

20

Degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) by the lignin-degrading basidiomycete Phanerochaete chrysosporium.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Degradation of the BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes) group of organopollutants by the white-rot fungus Phanerochaete chrysosporium was studied. Our results show that the organism efficiently degrades all the BTEX components when these compounds are added either individ...

Yadav, J S; Reddy, C A

 
 
 
 
21

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

UK PubMed Central (United Kingdom)

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.

Herbinet O; Husson B; Ferrari M; Glaude PA; Battin-Leclerc F

2013-01-01

22

Photodissociation spectroscopy of (benzene-toluene)+. Charge delocalization in the hetero-dimer ion  

International Nuclear Information System (INIS)

The electronic spectrum of the benzene-toluene hetero-dimer ion is measured in the 380-1400 nm region. The spectrum shows intense bands around 1175 and 670 nm and a weaker band around 920 nm, which correspond to charge resonance (CR) bands of homo-dimer ions. The observation indicates that the positive charge stays on the benzene part in some probability, although the ionization potential of benzene is 0.4162 eV higher than that of toluene. A local excitation (LE) band is observed around 420 nm, where a ?relata of a relation? transition is locally excited in the charged benzene or toluene molecule. On the basis of the positions of the CR-like bands, as well as the intensity of the LE band relative to that of homo-dimer ions, the probability of finding the charge on the benzene molecule is analyzed to be approximately 36%. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

1998-12-15

23

Engineering case report. Toluene and methyl ethyl ketone exposure from a commercially available contact adhesive.  

UK PubMed Central (United Kingdom)

A maintenance worker became ill after working indoors over the course of 3 days with a commercially available contact adhesive containing toluene and methyl ethyl ketone. Respiratory protection or local exhaust ventilation was not used. The worker subsequently suffered from numerous medical symptoms including tremors and elevated blood pressure. Magnetic resonance imaging documented the occurrence of encephalopathy. The worker has alleged that the cause of these effects was exposure to the vapors from the contact adhesive. The objective of this study was to characterize/estimate the level of the worker's exposure by obtaining air samples in an exposure chamber while performing similar activities under similar conditions. We found that the worker may have been exposed to approximately 159 ppm toluene and 58 ppm methyl ethyl ketone 8-hr time-weighted averages for 8 hr of adhesive application. The maximum 15-min average exposures were 233 ppm toluene and 85 ppm methyl ethyl ketone.

Mills WJ; Grigg BJ; Offermann FJ; Gustin BE; Spingarn NE

2012-01-01

24

Engineering case report. Toluene and methyl ethyl ketone exposure from a commercially available contact adhesive.  

Science.gov (United States)

A maintenance worker became ill after working indoors over the course of 3 days with a commercially available contact adhesive containing toluene and methyl ethyl ketone. Respiratory protection or local exhaust ventilation was not used. The worker subsequently suffered from numerous medical symptoms including tremors and elevated blood pressure. Magnetic resonance imaging documented the occurrence of encephalopathy. The worker has alleged that the cause of these effects was exposure to the vapors from the contact adhesive. The objective of this study was to characterize/estimate the level of the worker's exposure by obtaining air samples in an exposure chamber while performing similar activities under similar conditions. We found that the worker may have been exposed to approximately 159 ppm toluene and 58 ppm methyl ethyl ketone 8-hr time-weighted averages for 8 hr of adhesive application. The maximum 15-min average exposures were 233 ppm toluene and 85 ppm methyl ethyl ketone. PMID:22548642

Mills, William J; Grigg, Benjamin J; Offermann, Francis J; Gustin, Barry E; Spingarn, Neil E

2012-01-01

25

Hydrogen isotope analysis of benzene and toluene emitted from vehicles  

Science.gov (United States)

The isotopic analysis of atmospheric volatile organic compounds (VOCs), and in particular their hydrogen isotope ratio (?2H), has the potential to be an effective tool for clearly identifying sources of VOCs. However, to date there have been very few such analyzes. Here, we have analyzed the ?2H values of VOCs using thermal desorption and chromatography, thermal conversion, and isotope ratio mass spectrometry (TD-GC/TC/IRMS). After determining the analytical conditions needed for high precision and accurate analysis, we adopted minimum peak area thresholds of 10 Vs for the low concentration samples and 15 Vs for other samples. We also confirmed that breakthrough during adsorption of samples would have only minimal effect. We found that the collected samples could be stored for at least 7 days. Precisions of 1.1‰-5.3‰ (n = 7) were obtained for 28 standard compounds in a standard gas containing 58 VOCs (C6-C11). Next, we collected the exhaust gas produced in cold mode and hot mode from five vehicles, and measured the ?2H values. For benzene, we found that the ?2H value for the hot mode vehicle emissions was 19.3-104.7‰ lighter than that for the cold mode, while the ?2H value of the vaporized gasoline was 0.7-25.2‰ close to that in the cold mode. It should, therefore, be possible to distinguish cold mode vehicle emissions from those of the hot mode by analyzing the hydrogen isotope ratio. For benzene, particularly, the difference in ?2H values between 2 modes is important since emitted in large quantity from vehicles generally. Additionally, we measured VOCs in vaporized gasoline and roadside air, and compared the results with those for vehicle emissions. The roadside samples were characterized mainly by the hot mode. It has been shown that the hot mode has a significant impact on roadside VOCs, if no isotopic fractionation in the atmosphere is assumed. The results suggest that our approach could improve our understanding of the origin and fate of atmospheric VOCs, by allowing measurement of the ?2H values of further target compounds and sources.

Kikuchi, Nami; Kawashima, Hiroto

2013-06-01

26

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

International Nuclear Information System (INIS)

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 CO2 and H2O. 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

1998-01-01

27

Sorption equilibria of benzene and toluene on two New Jersey coastal plain ground water aquifer solids  

Energy Technology Data Exchange (ETDEWEB)

Studies examining sorption equilibria of benzene and toluene to New Jersey coastal plain aquifer solids were performed. Adsorption to the Cohansey aquifer solids, a coarse to fine grade sand with a 2.6% organic carbon content, and to the Potomac-Raritan-Magothy aquifer solids, a sandy loam with a 1.3% organic carbon content, was found to be dependent on adsorber mass. Equilibrium adsorption could be characterized by either linear or Freundlich isotherms. Toluene exhibited a greater affinity to sorb than benzene. Greater adsorption was in general observed for both substances to the Cohansey material, which was attributed to its greater organic matter (carbon) content. Consecutive desorption experiments displayed an apparent hysteresis.

Uchrin, C.G.; Mangels, G.

1987-01-01

28

Determination of benzene - and toluene traces, in ethanol, by gas chromatography and a photoionization detector  

International Nuclear Information System (INIS)

[en] Analysis results of a set of samples of ethanol containing benzene and toluene traces, using gas chromatography and a photoionization detector are presented. (A.R.H.)[pt] Apresentam-se os resultados da analise de uma serie de amostras de etanol contendo tracos de benzeno e tolueno, utilizando-se a cromatografia a gas com um detector de foto-ionizacao. (A.R.H.)

1981-01-01

29

Effect of temperature and dissolved oxygen on the growth kinetics of Pseudomonas putida F1 growing on benzene and toluene.  

Science.gov (United States)

Batch experiments were conducted to determine the effect of temperature and dissolved oxygen concentration on the rates of growth and substrate (benzene and toluene) degradation by the toluene degrading strain, Pseudomonas putida F1. Over a range of temperature from 15 to 35 degrees C the maximum specific growth rate followed the Topiwala-Sinclair relationship when either benzene or toluene served as the sole carbon and energy source. Oxygen limited growth followed Monod saturation kinetics with the specific growth rate given as a function of the dissolved oxygen concentration. The oxygen half-saturation coefficient was found to be approximately 1 mg/l regardless of whether benzene or toluene was the substrate. Similar experiments with Burkholderia (Ralstonia) pickettii PKO1 for grown on toluene revealed an oxygen half-saturation coefficient of 0.7 mg/l. PMID:14664855

Alagappan, Gunaseelan; Cowan, Robert M

2004-02-01

30

Effect of temperature and dissolved oxygen on the growth kinetics of Pseudomonas putida F1 growing on benzene and toluene.  

UK PubMed Central (United Kingdom)

Batch experiments were conducted to determine the effect of temperature and dissolved oxygen concentration on the rates of growth and substrate (benzene and toluene) degradation by the toluene degrading strain, Pseudomonas putida F1. Over a range of temperature from 15 to 35 degrees C the maximum specific growth rate followed the Topiwala-Sinclair relationship when either benzene or toluene served as the sole carbon and energy source. Oxygen limited growth followed Monod saturation kinetics with the specific growth rate given as a function of the dissolved oxygen concentration. The oxygen half-saturation coefficient was found to be approximately 1 mg/l regardless of whether benzene or toluene was the substrate. Similar experiments with Burkholderia (Ralstonia) pickettii PKO1 for grown on toluene revealed an oxygen half-saturation coefficient of 0.7 mg/l.

Alagappan G; Cowan RM

2004-02-01

31

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

International Nuclear Information System (INIS)

The structures of benzene (C6H6, C6D6) and toluene (C6H5-CH3, C6D5-CD3) 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 cm2/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).

1981-01-01

32

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

International Nuclear Information System (INIS)

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 ?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 ben(>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 site remedial with a mobile Electron Beam facility. (Author)

1998-01-01

33

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

International Nuclear Information System (INIS)

Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO2, SO2, O3, benzene, and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO2 concentrations were anti-correlated to the O3 concentrations, is expected. SO2 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. SO2 concentrations and to a lesser extent, those of NO2 and O3, 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 O3 and SO2 data are in general in good agreement, but our NO2 concentrations seem to be generally higher. (author)

2002-01-01

34

Occupational exposure to benzene, toluene, xylene and ethylbenzene during routine offshore oil and gas production operations  

Energy Technology Data Exchange (ETDEWEB)

The main objective of the project was to measure full-shift time weighted average personal exposures to benzene across a representative range of tasks and installations in the offshore industry. This would enable HSE and UKOOA to establish an overview of benzene exposure for typical operations and to assess the impact that the lowering of the Maximum Exposure Limit (from 5 ppm to 1 ppm) would have on the offshore industry. Although benzene was of primary interest, the sampling tubes were also analysed for other aromatic hydrocarbons of interest offshore (toluene, xylene and ethylbenzene). Over 91% of the results for benzene (current MEL, 5 ppm) were below 0.05 ppm. 6.2% were greater than 0.1 ppm. The 50th percentile was less than the limit of detection, the 95th percentile was 0.11 ppm and the 99th percentile was 0.502 ppm. The benzene results were analysed by Installation, Installation Type, Job Type and Shift. Although not statistically significant, analysis of Variance of the data suggested that: (1) gas and condensate installations had the highest average exposures; (2) laboratory and production chemists, plant operators and supervisors had higher average exposures than mechanical and instrument technicians, and marine crew; and (3) night shift exposures are higher than day shift exposures. Results for the three other analytes were generally low. Only three results for toluene (OES, 50 ppm) were greater than 0.5 ppm, the 99th percentile being 0.58 ppm. Five results for xylene (OES, 100 ppm) were greater than 1 ppm, the highest being 2.4 ppm. Two of the five results were from workers who were painting. The highest result for ethylbenzene (OES, 100 ppm) was 0.63 ppm. In certain cases it is possible to link higher exposures with certain job descriptions provided by the surveyor but given the values of these results with respect to the relevant OES, no further analysis was made. (author)

Whiteley, S.; Plant, S. [Health and Safety Laboratory (United Kingdom)

2000-02-01

35

Proton exchange in gas-phase isopropylation of benzene and toluene  

International Nuclear Information System (INIS)

[en] In the gas-phase radiolysis of a C3H8 (100 mm)-C6H6 (5 mm)--C6D6 (5 mm) mixture, it has been found that the isopropylbenzene (IPB) produced by the attack of the i-C3H7+ ions derived from propane to benzene involves IPB-d1, -d2, -d3, and -d4 as well as IPB-d6 and -d5, and the relative yields of these IPBs increase with increasing degree of the H--D exchange. The result suggests that the proton exchange between the rings of the intermediate complexes, C3H7C6H6+ and C3H7C6D6+ and of the reactant benzene molecules occurs. The degree of the H--D exchange decreases with increasing temperature. The H--D exchange during the isopropylation has also been studied in propane--toluene and propane--benzene--toluene systems. The reversible ? complex formation between the intermediate complexes and the reactant aromatic molecules followed by the proton exchange has been proposed. 6 figures

1978-04-12

36

Biofiltration of odours - industrial pilot to treat methyl ethyl ketone and toluene  

Energy Technology Data Exchange (ETDEWEB)

Methyl ethyl ketone and toluene in the off-gases of a plant producing polyvinyl chloride sheeting for the automotive industry and swimming pools caused frequent odour complaints from the neighbourhood. A pilot project was developed to investigate the removal of the compounds under actual operating conditions by passing part of the exhaust through a compost-based, three-stage biofilter. It was determined over the 156 days of operation that the removal efficiencies of methyl ethyl ketone and toluene averaged 73% and 49%, respectively. It was also shown that shutdowns and disruptions of the laminating process for short and extended periods did not affect the biofilter performance. Addition of 100g/L solution of KNO{sub 3} as a nitrogen source did not improve the performance. Carbon dioxide concentration data and the presence of an average microbial population of 52 million colony forming units per gram provided evidence that biological degradation played a significant role in the reduction of methyl ethyl ketone and toluene in the off-gases of the laminator. (author)

Otten, L.; Elsie, K. [Univ. of Guelph, School of Engineering, Guelph, Ontario (Canada)

2002-06-15

37

Evaluation of solar photosensitization of benzene, toluene and Escherichia coli with methylene blue and rose bengal  

Energy Technology Data Exchange (ETDEWEB)

There exists a need for research, at all levels, tailored to address the needs of smaller, and possibly lesser developed, communities. One such area for research is the simultaneous disinfection and detoxification of a mildly contaminated water source. While photosensitization has been studied for disinfection, most of the work with regard to microorganisms has been done in the medical field. Research was conducted to provide preliminary determination of the efficacy of two dyes, methylene blue and rose bengal, for simultaneous photosensitized disinfection and detoxification. Specifically, the destruction of the aromatic hydrocarbons benzene and toluene, and the bacteria Escherichia coli, were investigated.

Cooper, A.T.; Goswami, D.Y.

1999-07-01

38

Simulating Retention in Gas-Liquid Chromatography: Benzene, Toluene, and Xylene Solutes  

Energy Technology Data Exchange (ETDEWEB)

Accurate predictions of retention times, retention indices, and partition constants are a long sought-after goal for theoretical studies in chromatography. Although advances in computational chemistry have improved the understanding of molecular interactions, little attention has been focused on chromatography, let alone calculations of retention properties. Configurational-bias Monte Carlo simulations in the isobaric-isothermal Gibbs ensemble were used to investigate the partitioning of benzene, toluene, and the three xylene isomers between a squalane liquid phase and a helium vapor phase. The united-atom representation of the TraPPE (Transferable Potentials for Phase Equilibria) force field was used for all solutes and squalane. The Gibbs free energies of transfer and Kovats retention indices of the solutes were calculated directly from the partition constants (which were averaged over several independent simulations). While the calculated Kovats indices of benzene and toluene at T = 403 K are significantly higher than their experimental counterparts, much better agreement is found for the xylene isomers at T = 365 K.

WICK,COLLIN D.; MARTIN,MARCUS G.; SIEPMANN, J. ILJA; SCHURE,MARK R.

2000-07-12

39

Genotoxicity and apoptosis in Drosophila melanogaster exposed to benzene, toluene and xylene: Attenuation by quercetin and curcumin  

International Nuclear Information System (INIS)

Monocyclic aromatic hydrocarbons (MAHs) such as benzene, toluene and xylene are being extensively used for various industrial and household purposes. Exposure to these hydrocarbons, occupationally or non-occupationally, is harmful to organisms including human. Several studies tested for toxicity of benzene, toluene and xylene, and interestingly, only a few studies looked into the attenuation. We used Drosophila model to test the genotoxic and apoptotic potential of these compounds and subsequently evaluated the efficiency of two phytochemicals, namely, quercetin and curcumin in attenuating test chemical induced toxicity. We exposed third instar larvae of wild type Drosophila melanogaster (Oregon R+) to 1.0-100.0 mM benzene, toluene or xylene, individually, for 12, 24 and 48 h and examined their apoptotic and genotoxic potential. We observed significantly (P

2011-05-15

40

Kinetics of liquid-phase hydrogenation of benzene on palladium catalysts and hydrogenation of toluene on palladium and platinum catalysts  

Energy Technology Data Exchange (ETDEWEB)

A kinetic study has been made of the liquid-phase hydrogenation of benzene of Pd/activated carbon at temperatures of 110-170/sup 0/C and pressures of 0.5-6 MPa. The experimental data are described by a kinetic equation obtained previously for liquid-phase hydrogenation of benzene on Pt and Ru catalysts. This equation is also applicable to the process of toluene hydrogenation of Pd (170/sup 0/) and Pt (90/sup 0/).

Konyukhov, V.Yu.; Tret' yakov, S.D.; Zyskin A.G.; Kul' kova, N.V.; Temkin, M.I.

1987-09-01

 
 
 
 
41

Conversion of toluene to benzene and mixed xylenes on old Thermofor Catalytic Cracking Units (TCC) in Russia  

Energy Technology Data Exchange (ETDEWEB)

World demand on toluene was in regression during the last years due to environmental and economical reasons, and there is a surplus of this compound from the processing to the petrochemical products. Disproportionation and transalkylation for the production of benzene and xylenes from toluene are now important industrial processes (Ikai Wang, 1999.). We analyze here the possibility of processing toluene on the Russian 43-102 'Houdry' type continuous Catalytic Cracking units (TCC), by studying the behaviour of EMCAT-100 catalyst on the disproportionation of toluene under the VHSV, temperature and catalyst/feed mass ratio characteristic for 43-102 facilities. Our previous results show that toluene disproportionation could be carried out on the Russian TCC units. (author)

Romero, Alfonso; Usachev, Nikolai Y.; Kalinin, Valera P. [Russian Academy of Sciences, Moscow (Russian Federation). Zelinsky Institute of Organic Chemistry]. E-mails: romero@orc.ru; ny@ioc.ac.ru

2004-07-01

42

Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples.  

UK PubMed Central (United Kingdom)

We present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications.

Iglesias RA; Tsow F; Wang R; Forzani ES; Tao N

2009-11-01

43

Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples.  

Science.gov (United States)

We present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications. PMID:19780581

Iglesias, Rodrigo A; Tsow, Francis; Wang, Rui; Forzani, Erica S; Tao, Nongjian

2009-11-01

44

The rate constants for reaction of ·OH radicals with benzene and toluene  

International Nuclear Information System (INIS)

[en] The rate constant for reaction of ·OH radical with toluene in aqueous solutions saturated with N2O or containing 0.1 M H2O2 has been determined by pulse radiolysis to be 8.1x109 l mol-1 s-1. This rate constant is comparable to the value of 7.8x109 l mol-1 s-1 for reaction with benzene determined under similar conditions. This latter rate constant provides a reference value of 1.3x109 l mol-1 s-1 with which to compare the partial rate constants for reaction of ·OH at the various positions of substituted aromatics. Comparison of the kinetic responses in the N2O and H2O2 systems provides a direct measure of the pseudo-first-order rate constant for reaction of ·O- with water as 7.9x107 s-1

2002-01-01

45

Degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) by the lignin-degrading basidiomycete Phanerochaete chrysosporium  

Energy Technology Data Exchange (ETDEWEB)

BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), from gasoline, aviation fuels, and industrial syntheses, frequently contaminate soil, sediments, and ground water. Both aerobic and anaerobic bacterial have been shown to degrade BTEX compounds, but no one pure strain of bacterial is known to degrade all components of BTEX efficiently. Phanerochaite chrysosporium, a naturally occurring wood-degrading white-rot fungus, has a versatile ability to degrade a wide spectrum of organopollutants. This paper investigates biodegradation of the BTEX components by P. chrysosporium. The results demonstrate that P. chrysosporium simultaneously degrades all the BTEX components and that this degradation is favored under nonligninolytic culture conditions when no designated lignin peroxidases(LIPs) and manganese-dependent peroxidases (MNPs) are produced.

Yadav, J.S.; Reddy, C.A. (Michigan State Univ., East Lansing (United States))

1993-03-01

46

HEADSPACE SOLID-PHASE MICROEXTRACTION FOR THE DETERMINATION OF BENZENE, TOLUENE, ETHYLBENZENES, AND XYLENES IN FOUNDRY MOLDING SAND  

Science.gov (United States)

The use of headspace solid-phase microextraction (HS-SPME) to determine benzene, toluene, ethylbenzene, and xylenes (BTEX) in foundry molding sand, specifically a 'green sand' (clay-bonded sand) was investigated. BTEX extraction was conducted using a 75'M Carboxen-polydimethylsiloxane (CAR-PDMS) fi...

47

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)

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.)

Dupont, L.

2001-02-01

48

Wetlands for the remediation of BTEX [benzene, toluene, ethylbenzene, xylenes] contamination: Amalgamation of policy and technology  

Energy Technology Data Exchange (ETDEWEB)

The fate and transport of benzene, toluene, ethylbenzene, and xylenes (BTEX) as they pass from a groundwater to a surface water environment was studied in three separate field experiments. The first examined the fate of BTEX from a spilled gasoline plume as it travelled vertically in the groundwater flow regime from a mineral soil unit through an organic soil unit to a surface wetland. The second considered surface water processes in the swamp that result in losses of BTEX concentrations. The final experiment evaluated the effects of seasonal and temporal changes on the processes occurring in the swamp that affect the fate and transport of BTEX under natural flow conditions. Significant reductions in BTEX were observed as the plume travelled vertically to reach the surface water. Reductions in contaminant levels were primarily due to sorption and biodegradation. On reaching the surface, overall reduction of compound concentration over 6 m of horizontal flow ranged from 92% for benzene to 85% for m-xylene. BTEX losses were mainly due to dilution, volatilization, and sorption. Limitations existing in the approach taken by present legislation and guidelines for wetland protection are discussed. Reactive legislation and guidelines should allow natural remediation of contamination in wetlands to be considered, especially when contaminant remediation requires alteration of the hydrologic flow regime or removal of contaminated material that may result in elimination of the wetland. 70 refs., 20 figs., 14 tabs.

Main, C.J.

1993-01-01

49

Adsorption of vapor-phase VOCs (benzene and toluene) on modified clays and its relation with surface properties  

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to investigate the potential use of modified clays for the adsorption of volatile organic compounds (VOCs) present in air. These VOCs which include toluene and benzene, are among the main air pollutants that represent a human health risk at high concentrations, mostly in indoor environments. In this study, a Mexican bentonite was used to prepare 3 modified clays, notably an organoclay (OC-CPC) by intercalating cetylpyridinium chloride (CPC); an aluminum-pillared clay (Al-PILC); and an inorganic-organic clay (IOC-CPC) prepared from Al-PILC intercalating CPC. Their structures were differentiated by infrared and thermogravimetric analyses, and the interlayer distance was assessed through X-ray diffraction. Toluene and benzene adsorption on OC-CPC was higher than in IOC-CPC and Al-PILC. Natural clay showed no adsorption capacity for these compounds. Comparison of the gas chromatography retention times for non polar and low-polarity compounds (octyne and benzene) in columns packed with OC-CPC and a commercial non polar column (squalene) showed that the OC-CPC possessed a higher organophilic (non polar) nature than squalene. This explains the higher benzene and toluene adsorption capacity of the OC-CPC compared with the other modified clays. It was concluded that organoclays represent a potential alternative for the adsorption of volatile organic compounds such as benzene and toluene present in indoor environments. Since the OC-CPC is hydrophobic by nature, the relative humidity of water vapour in the environment would not affects its adsorption capacity. 27 refs., 5 tabs., 5 figs.

Lopez-Cortes, C.; Gallardo-Velazquez, T.; Arellano-Cardenas, S. [National School of Biological Sciences (Mexico). Biophysics Dept.; Osorio-Revilla, G. [National School of Biological Sciences (Mexico). Biochemical Engineering Dept.

2008-04-15

50

Effects of packing material on the biofiltration of benzene, toluene and xylene vapours.  

UK PubMed Central (United Kingdom)

Biofiltration was used to eliminate volatile organic compounds from air streams in bench-scale reactors inoculated with an adapted consortium. Organic and inert supports were tested on 100 days of operation. The supports were: peat, vermiculite, a mixture of vermiculite and activated carbon, tree bark and, porous glass Rashig rings. A mixture of benzene, toluene and xylene vapors with a load of 200 gC m(-3) h(-1) was fed to the biofilters with an empty bed residence time of 60 s. Removal efficiencies higher than 95% were obtained with the mixture of vermiculite and activated carbon, 85% for peat and bark, 80% for vermiculite and 65% for the Rashig rings. In all cases, drying problems in beds were observed after several days of operation. Water addition with or without nutrients was required to maintain and increase the performance of biofilters. In steady state operation, experiments at loads ranging from 50 to 400 gC m(-3) h(-1) were carried out and a maximum elimination capacity of 260 gC m(-3) h(-1) was obtained for vermiculite-activated carbon support. The three xylene isomers were degraded. Observations of the supports surface by scanning electronic microscopy at the end of the biofiltration experiment showed abundant growth of fungi, which were not in the inoculum, had colonized the biofilter.

Ortiz I; Revah S; Auria R

2003-03-01

51

Research on benzene, toluene and dimethylbenzene detection based on a cataluminescence sensor.  

UK PubMed Central (United Kingdom)

We present a sensitive and quick way to determine benzene, toluene and dimethylbenzene (BTEX) in air, applying a cataluminescence (CTL) sensor based on a nano-sized composite material, ?-Al2 O3 /PtO2 . The factors that affect the sensor's performance were studied, including the sensing material, temperature, rate of air carrier and wavelength. It was shown that when Pt accounted for 0.2% of the sensing material, the rate of the air carrier that carries target gas was 450?mL/min, the determination wavelength was 400?nm and temperature was 236°C, this sensor showed the best CTL intensity to BTEX. In addition, the CTL intensity had a high linear relation with the concentration of BTEX, with a linear range from 0.5 to 100?mL/m(3) , and a detection limit 0.22?mL/m(3) . This nano-sized material had a quick response within 1.5?s, short recovery time within 1?min and a long lifetime, showing good potential for a variety of applications. Copyright © 2013 John Wiley & Sons, Ltd.

Sun Y; Cao X; Liu Y; Wang N; He R

2013-05-01

52

Research on benzene, toluene and dimethylbenzene detection based on a cataluminescence sensor.  

Science.gov (United States)

We present a sensitive and quick way to determine benzene, toluene and dimethylbenzene (BTEX) in air, applying a cataluminescence (CTL) sensor based on a nano-sized composite material, ?-Al2 O3 /PtO2 . The factors that affect the sensor's performance were studied, including the sensing material, temperature, rate of air carrier and wavelength. It was shown that when Pt accounted for 0.2% of the sensing material, the rate of the air carrier that carries target gas was 450?mL/min, the determination wavelength was 400?nm and temperature was 236°C, this sensor showed the best CTL intensity to BTEX. In addition, the CTL intensity had a high linear relation with the concentration of BTEX, with a linear range from 0.5 to 100?mL/m(3) , and a detection limit 0.22?mL/m(3) . This nano-sized material had a quick response within 1.5?s, short recovery time within 1?min and a long lifetime, showing good potential for a variety of applications. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23681937

Sun, Yan; Cao, Xiaoan; Liu, Yonghui; Wang, Nijing; He, Ruiwen

2013-05-17

53

Subclinical effects of groundwater contaminants. Pt. 4. Effects of repeated oral exposure to combinations of benzene and toluene on regional brain monoamine metabolism in mice  

Energy Technology Data Exchange (ETDEWEB)

The effect of combined treatment with benzene and toluene on the endogenous concentrations of the catecholamines norepinephrine (NE) and dopamine (DA), the catecholamine metabolites vanillylmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the indoleamine serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA), were investigated in six discrete brain regions of CD-1 mice. Groups of male, adult mice were continuously exposed to benzene (166 mg/l), toluene (80 and 325 mg/l), and combinations of benzene + toluene (80 or 325 mg/l) in drinking water for 4 weeks. Benzene produced increases of NE in the hypothalamus, cortex, midbrain and medulla oblongata, DA in the hypothalamus and corpus striatum, and 5-HT in all dissected brain regions except cerebellum. Elevated levels of various monoamine metabolites were also observed in these brain areas. Toluene ingestion alone also significantly increased the concentrations of NE, DA, 5-HT, and their metabolites in several brain regions. Mice given the combined treatments exhibited raised regional neurochemical levels when compared to the untreated controls. Increased concentrations of biogenic amine metabolites in several brain regions were greater in the combined exposures of benzene and toluene than when either chemical was used alone. The findings were different from those observed on immune parameters using similar treatment protocols, where simultaneous exposure to toluene prevented the immunotoxic effects of benzene. (orig./MG).

Hsieh, G.C.; Parker, R.D.R. (Utah State Univ., Logan, UT (USA). Dept. of Biology); Sharma, R.P. (Utah State Univ., Logan, UT (USA). Dept. of Animal, Dairy and Veterinary Sciences)

1990-11-01

54

Development of portable preconcentration-gas chromatography system for fast analysis of trace benzene, toluene and xylene in air  

International Nuclear Information System (INIS)

An automated on-line portable preconcentration-short column gas chromatography was developed, which used preconcentrator using adsorption tube with Tenax-GR and Curie-point heating. The developed system operated with 3 steps of processing, preconcentration, thermal desorption, and analysis and cleaning, and could continued operating within 1 ? 2 min cycle. The recoveries of preconcentrator for toluene was ranged between 94.7±6.6% and 103.8±3.1% with less than 7% of RSD. For benzene, toluene and xylene(BTX) standard gas test, IDL was 41, 49, 472 ng/m3 benzene, toluene and ?-xylene, respectively. The BTX mixture was analyzed within 30 sec with baseline separation by the system equipped with 4 m long capillary column. The deficiency of separation power caused by short column was solved by the control of sample injection volume and inlet/outlet pressure ratio. The automated portable preconcentration-short column gas chromatograph system was found to be useful for the continuous air monitoring of BTX at ppb levels ambient air

2001-01-01

55

Removal of toluene and benzene from flue gas by a biotrickling filtration system which uses an urethane foam filter  

Energy Technology Data Exchange (ETDEWEB)

A lab-scale research was conducted to study the toluene/benzene removal performance of a biotrickling filtration system. Urethane foam, which constituted a lattice-like structure internally, was used as the microbial carrier for the removal. This structure was found to be effective for minimizing drops in pressure (due to clogging), even under high space velocity conditions. The large specific surface area of the carrier (1200 m2/m3) also contributed to better removal performance. The space velocity (versus the packed bed) at 500 h-1(100 h-1 for most conventional biofiltration systems). Provided the target removal performance is obtained by such configuration, it may become possible to reduce the size of the biofiltration packed bed to one-fifth of that of conventional biofiltration systems. The test apparatus included a hard vinyl chloride column into which the microbial carrier was charged (layer of 500 mm). A nutrient solution, consisting of tap water mixed with nitrogen and phosphorus, was intermittently supplied into the column. The supply of nitrogen sources for microbial growth was regulated (ratio by weight versus the organic carbon load: Nitrogen:Carbon = 15:100) for improving removal performance. The temperature inside the column was maintained at 25. The flue gas was prepared by using reagent grade chemicals. The concentration of toluene and benzene was set at about 30 ppm. Following treatment of two months, the average removal percentages of toluene and benzene were 82% and 62%, respectively. On the other hand, average pressure drops (due to clogging) of the same were small, 12.8 mmH{sub 2}O/m and 7.2 mmH{sub 2}O/m, respectively. Such results indicated that this biotrickling filtration system using urethane foam has great potential as a considerably downsized system.

Yamashita, Shigeki; Kitagawa, Mashayoshi [EBARA Research Co., Ltd., Fujisawa (Japan). Center for Technology Development

1998-12-31

56

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

International Nuclear Information System (INIS)

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.

1998-01-01

57

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)

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.

1918-11-11

58

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)

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 ?g/L for benzene, 0.70 ?g/L for toluene, and 1.54 ?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 ?g/L to 2.0 ?g/L, the concentration of toluene varied from 60Co, 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)

2006-01-01

59

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

International Nuclear Information System (INIS)

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 ?M. Apart from MTBE, the spin traps, 5,5-dimethyl-pyrroline-N-oxide (DMPO) and N-tert-butyl-?-phenylnitrone (PBN) can decrease the level of DNA damage in BTEX at 200 ?M. 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 ?M. 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.

2008-05-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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 {mu}M. Apart from MTBE, the spin traps, 5,5-dimethyl-pyrroline-N-oxide (DMPO) and N-tert-butyl-{alpha}-phenylnitrone (PBN) can decrease the level of DNA damage in BTEX at 200 {mu}M. 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 {mu}M. 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.

Chen, Colin S. [Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 824, Taiwan (China); Hseu, You C. [Department of Cosmeceutics, China Medical University, Taichung, Taiwan (China); Liang, Shih H.; Kuo, J.-Y. [Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 824, Taiwan (China); Chen, Ssu. C. [Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 824, Taiwan (China)], E-mail: osycchna@ksts.seed.net.tw

2008-05-01

 
 
 
 
61

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

UK PubMed Central (United Kingdom)

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 point source emissions cause substantial variation in street-level exposures to common toxic volatile organic compounds in New York City. Land-use regression models were successfully developed for benzene, formaldehyde, and total BTEX using spatial indicators of on-road vehicle emissions and emissions from stationary sources. These estimates will improve the understanding of health effects of individual pollutants in complex urban pollutant mixtures and inform local air quality improvement efforts that reduce disparities in exposure.

Kheirbek I; Johnson S; Ross Z; Pezeshki G; Ito K; Eisl H; Matte T

2012-01-01

62

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

Energy Technology Data Exchange (ETDEWEB)

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.)

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

63

Effect of substrate interaction on the degradation of methyl tert-butyl ether, benzene, toluene, ethylbenzene, and xylene by Rhodococcus sp.  

UK PubMed Central (United Kingdom)

It was examined the substrate interactions of benzene (B), tolulene (T), ethylbenzene (E), xylene (X), and methyl tert-butyl ether (M) in binary, ternary, quaternary, and quinary mixtures by Rhodococcus sp. EH831 that could aerobically degrade all of five single components. The specific degradation rates (SDRs) of B, T, E, X, and M were 234, 913, 131, 184 and 139 micromol g-dry cell weight (DCW)(-1)h(-1), respectively. In binary, ternary, quaternary, and quinary mixtures of them, ethylbenzene was the strongest inhibitor for the other substrates, and methyl tert-butyl ether was the weakest inhibitor. Interestingly, no degradation of benzene and methyl tert-butyl ether was found in the coexistence of ethylbenzene. The degradation of benzene followed only after toluene became exhausted when both was present. Ethylbenzene was least inhibited by methyl tert-butyl ether and most inhibited by toluene.

Lee EH; Cho KS

2009-08-01

64

Interaction between the aromatic hydrocarbons benzene, toluene, ethylbenzene, p-, m-, o-xylene and the alga Selenastrum capricornutum: Hydrocarbon toxicity, bioconcentration and physiological effects  

Energy Technology Data Exchange (ETDEWEB)

An airtight exposure system was employed for toxicity testing of 6 volatile aromatic hydrocarbons collectively referred to as BTEX (benzene, toluene, ethylbenzene, and xylenes) using the green unicellular alga Selenastrum capricornutum. Relative toxicity of the aromatics, in order of increasing toxicity, was benzene, toluene, ethylbenzene, and p-, m-, and o-xylene. Examination of the toxicity of hydrocarbon mixtures revealed an additive toxicological interaction between benzene, toluene, and m-xylene. A synergistic interaction between toluene and benzene was evident at higher concentration levels. Bioconcentration values, defined as the log of the ratio between the amount sorbed and the total amount added to the aqueous medium, ranged from 1.63 for benzene to 2.41 for p-xylene. Both bioconcentration and toxicity strongly correlated with the octanol/water partition coefficient. The microsome intracellular component was found to bioconcentrate aromatics to the same degree as the whole cell. The impact of BTEX on membrane integrity was examined by [sup 14]C and fluorescent dye techniques. Exposure of algal cells to increasing benzene or o-xylene concentrations resulted in a significant release of labelled photosynthates. Exposure of cells to increasing concentrations of a BTEX mixture for 24 h resulted in a 35-90% reduction in the ability of the cells to retain the uranin dye stain. The same BTEX concentrations were found to inhibit algal growth by 25-99% after an 8-d exposure period. No conclusive evidence of algal biodegradation of the aromatics was found. 132 refs., 30 figs., 8 tabs.

Herman, D.C.

1990-01-01

65

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)

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.

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

66

Determination of Benzene, Toluene and Xylene (BTX) Concentrations in Air Using HPLC Developed Method Compared to Gas Chromatography  

Directory of Open Access Journals (Sweden)

Full Text Available A new method for analysis of benzene, toluene, and xylene (BTX) using High Performance Liquid Chromatography-UV detection (HPLC-UV) is described and compared to the gas chromatography (GC) method. A charcoal adsorption tube connected to a small pump was used to obtain samples from an atmosphere chamber standard. Samples were extracted with methanol and analyzed by HPLC-UV. Chromatography was isocratic in a mobile phase consisting of water-methanol (30-70). The flow rate was set at 1 ml/min. The analyses were completely separated and were quantified using both methods. The results demonstrated no statistically significant differences between BTX concentrations between the two analytical methods with a correlation coefficient of 0.98-0.99. The GC method provided higher sensitivity than HPLC, but the HPLC determination of BTX were applicable to real samples because its sensivity was lower than the thershold limit recommended by the American Conference of Governmental Industrial Hygienist (ACGIH) for an 8-hour workday.

Abdulrahman Bahrami; Hosien Mahjub; Marzieh Sadeghian; Farideh Golbabaei

2011-01-01

67

Separation of toluene from alkanes using 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid at T = 298.15 K and atmospheric pressure  

International Nuclear Information System (INIS)

In this paper, the separation of toluene from aliphatic hydrocarbons (heptane, or octane, or nonane) was analyzed by solvent extraction with 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid, [EMpy][ESO4]. Liquid-liquid equilibrium (LLE) data for the ternary systems {heptane (1) + toluene (2) + [EMpy][ESO4] (3)}, {octane (1) + toluene (2) + [EMpy][ESO4] (3)}, and {nonane (1) + toluene (2) + [EMpy][ESO4] (3)} were obtained by measurements at T = 298.15 K and atmospheric pressure. The selectivity, % removal of aromatic, and solute distribution ratio, obtained from experimental equilibrium results, were used to determine the ability of [EMpy][ESO4] as a solvent. The degree of consistency of the experimental LLE values was ascertained using the Othmer-Tobias and Hand equations. The experimental results for the ternary systems were correlated with the NRTL model. Finally, the results obtained were compared with other ionic liquids and other solvents.

2010-01-01

68

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)

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 site remedial with a mobile Electron Beam facility. (Author)

Gonzalez Vanderhaghen, D.E

1998-12-31

69

Purifying a fraction of coke chemical benzene, toluene and xylene using concentrated sulfuric acid with an additive of alpha methylstyrol fraction  

Energy Technology Data Exchange (ETDEWEB)

C6H6 with a thiophene content of 0.05 to 0.08 percent is produced with purification of a benzene, toluene and xylene fraction by a known method using concentrated H2SO4. The purification of a benzene, toluene and xylene (BTK) fraction with a thiophene content of 0.55 percent at 20 to 80 degrees using 2 to 8 percent concentrated H2SO4 with an additive of 0.5 to 4 percent alpha methylstyrol fraction (MSF), produced as a by product in synthesis of phenol by a coumol method is studied in laboratory conditions. It is established that in order to produce C6H6 with a thiophene content of less than 0.01 percent from a benzene, toluene and xylene fraction by means of S2SO4 with an additive of 2.5 percent alpha methylstyrol fraction, greater than or equal to 5 percent H2SO4 is required. With the same volume of H2SO4, a 6 percent additive of 0.5 to 4 percent alpha methylstryol fraction reduces the content of the thiophene in the C6H6 to 0.0120 to 0.0010 percent. The most effective purification is at 40 degrees, a 5 percent concentration of H2SO4 and an additive of 2 to 2.5 percent alpha methylsytrol fraction. The results of laboratory tests are confirmed in commercial tests.

Tecza, W.; Lisicki, Z.

1984-01-01

70

Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer.  

UK PubMed Central (United Kingdom)

The capabilities of a portable mass spectrometer for real-time monitoring of trace levels of benzene, toluene, and ethylbenzene in air are illustrated. An atmospheric pressure interface was built to implement atmospheric pressure chemical ionization for direct analysis of gas-phase samples on a previously described miniature mass spectrometer (Gao et al. Anal. Chem.2006, 78, 5994-6002). Linear dynamic ranges, limits of detection and other analytical figures of merit were evaluated: for benzene, a limit of detection of 0.2 parts-per-billion was achieved for air samples without any sample preconcentration. The corresponding limits of detection for toluene and ethylbenzene were 0.5 parts-per-billion and 0.7 parts-per-billion, respectively. These detection limits are well below the compounds' permissible exposure levels, even in the presence of added complex mixtures of organics at levels exceeding the parts-per-million level. The linear dynamic ranges of benzene, toluene, and ethylbenzene are limited to approximately two orders of magnitude by saturation of the detection electronics.

Huang G; Gao L; Duncan J; Harper JD; Sanders NL; Ouyang Z; Cooks RG

2010-01-01

71

Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer.  

Science.gov (United States)

The capabilities of a portable mass spectrometer for real-time monitoring of trace levels of benzene, toluene, and ethylbenzene in air are illustrated. An atmospheric pressure interface was built to implement atmospheric pressure chemical ionization for direct analysis of gas-phase samples on a previously described miniature mass spectrometer (Gao et al. Anal. Chem.2006, 78, 5994-6002). Linear dynamic ranges, limits of detection and other analytical figures of merit were evaluated: for benzene, a limit of detection of 0.2 parts-per-billion was achieved for air samples without any sample preconcentration. The corresponding limits of detection for toluene and ethylbenzene were 0.5 parts-per-billion and 0.7 parts-per-billion, respectively. These detection limits are well below the compounds' permissible exposure levels, even in the presence of added complex mixtures of organics at levels exceeding the parts-per-million level. The linear dynamic ranges of benzene, toluene, and ethylbenzene are limited to approximately two orders of magnitude by saturation of the detection electronics. PMID:19879158

Huang, Guangming; Gao, Liang; Duncan, Jason; Harper, Jason D; Sanders, Nathaniel L; Ouyang, Zheng; Cooks, R Graham

2009-09-30

72

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)

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.

Daoxiang Zhang; Taihe Xiang; Li Peihan; Lumin Bao

2011-01-01

73

Volumetric properties of binary liquid mixtures: Application of the Prigogine-Flory-Patterson theory to excess molar volumes of dichloromethane with benzene or toluene  

International Nuclear Information System (INIS)

[en] The values of the density were measured for binary liquid mixtures of benzene and toluene with dichloromethane over entire range of concentration using a vibrating-tube densimeter at T = (288.15, 293.15, 298.15, and 303.15) K and atmospheric pressure. The excess molar volumes, calculated from the density results, are positive for the systems of dichloromethane with benzene over the whole concentration range and present an approximate sigmoid curve for the dichloromethane with toluene. The VmE values have been fitted to the Redlich-Kister polynomial equation, and other volumetric properties such as the partial molar volumes, Vi-bar, the apparent molar volume, V?i, and the partial molar excess volumes at infinite dilution, (ViE-bar)?, were calculated over the whole composition range. The Prigogine-Flory-Patterson (PFP) theory and its applicability in predicting VmE at T = 298.15 K are tested. Good agreement was found for the mixtures dichloromethane with benzene. For the mixtures dichloromethane with toluene, which shows an approximate S-shaped VmE behaviour, the correlation fails.

2009-01-01

74

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

UK PubMed Central (United Kingdom)

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.

Zhang D; Xiang T; Li P; Bao L

2011-10-01

75

Optimization of SPE for Analysis of Mandelic Acid as a Biomarker of Exposure to Ethyl Benzene  

Directory of Open Access Journals (Sweden)

Full Text Available Ethyl benzene is an important constituent of widely used solvents in industries and laboratories, causing widespread environmental and industrial pollutions. For evaluation of occupational exposure to such pollutants, biological monitoring is an essential process, in which, preparation of environmental and biological samples is one of the most time-consuming and error-prone aspects prior to chromatographic techniques. The use of solid-phase extraction (SPE) has been grown and is a fertile technique of sample preparation as it provides better results than those of liquid-liquid extraction (LLE). In this study, SPE using bonded silica has been optimized with regard to sample pH, sample concentration, elution solvent, elution volume, sorbent type, and sorbent mass. Through experimental evaluation, a strong anion exchange silica cartridge (SAX) has been found successful in simplifying sample preparation. The present approach proved that, mandelic acid could be retained on SAX sorbent based on specific interaction. Further study was employed using 10% acetic acid to extract the analyte from spiked urine and gave a clean sample for HPLC-UV system. In this study, a high performance liquid chromatography, using reverse-phase column was used. The isocratic run was done at a constant flow rate of 0.85 ml/min, the mobile phase was water/methanol/acetic acid and a UV detector was used, setting at 225 nm. At the developed conditions the extraction recovery was exceeded 98%. The factors were evaluated statically and also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments.

SJ Shahtaheri, M Abdollahi, F Golbabaei, A Rahimi-Froushani, F Ghamari

2004-01-01

76

Benzene, toluene, ozone, NO{sub 2} and SO{sub 2} measurements in an urban street canyon in Thessaloniki, Greece  

Energy Technology Data Exchange (ETDEWEB)

Benzene, toluene, sulphur dioxide, ozone and nitrogen dioxide were measured at a mean level of 13.5 m above ground in a narrow, four-lane street canyon (height 30 m, width 20 m) in Thessaloniki, Greece during the period January-July 1997 by means of a commercial differential optical absorption spectrometer (OPSIS DOAS). Primary pollutant levels were found to be 2.5-4.4 times higher during the cold part of the year than during the warm part of the year, the winter/summer ratio increasing with the reaction rate constant with OH for each of the measured species. Ozone, on the other hand, exhibited a winter/summer ratio of 0.36. NO{sub 2} originates from both primary and secondary sources; its winter/summer concentration ratio of 1.4 lies, therefore, between those of primary pollutants and ozone. Pollution levels were influenced considerably by wind speed, while for the street canyon under study wind direction did not influence pollutant levels considerably. While primary pollution was found to decrease with increasing wind speed, ozone increased. Benzene mean levels during the study period were around 6 ppb and hence much higher than the EU annual limit value of 5 {mu}g m{sup -3} (1.44 ppb at STP). Toluene mean levels were around 14 ppb and hence also several times above the WHO recommendation of 2 ppb for 24 h. The apportionment of traffic emissions in four time zones used in most inventories in urban airshed models was tested using benzene and toluene measurements at low (<1 m s {sup -1}) wind speeds. The agreement between model emissions and calculated emissions apportionment into the four time zones was good, except for Zone D (23:00-1:59), where model inventory emissions were somewhat too low. (author)

Kourtidis, K.A.; Ziomas, I.; Zerefos, C.; Kosmidis, E.; Symeonidis, P.; Christophilopoulos, E.; Karathanassis, S. [Aristotle University of Thessaloniki (Greece). Physics Department, Laboratory of Atmospheric Physics; Mploutsos, A. [Aristotle University of Thessaloniki (Greece). Department of Geology, Laboratory of Meteorology and Climatology

2002-11-01

77

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)

A radiochemical solvent extraction procedure has been developed for the determination of As(III) using 76As 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

1994-01-01

78

2,4-Dichloro-1-[1-(2,4-dichlorobenzyloxy)ethyl]benzene  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C15H12Cl4O, the dihedral angle between the least-squares planes of the two benzene rings is 82.6?(9)°. The dihedral angles between the COC mean plane of the oxy group and the two benzene rings are 84.3?(5) and 10.8?(5)°. In the crystal, two weak ?–? interactions [centroid–centroid distances = 3.9989?(8) and 3.7912?(8)?Å] and a C—H...? interaction are observed.

Jerry P. Jasinski; Ray J. Butcher; C. S. Chidan Kumar; H. S. Yathirajan; B. Narayana

2010-01-01

79

N,N?-Bis(2-hydroxy­ethyl)benzene-1,4-dicarboxamide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mol­ecule of the title compound, C12H16N2O4, is centrosymmetric and the amide group is twisted relative to the benzene ring by 14.40?(13)°. The mol­ecules are hydrogen bonded into a three-dimensional framework, with the hydr­oxy O atoms acting as acceptors in N—H?O hydrogen bonds and as donors i...

Bednarek, Gabriela; Kusz, Joachim; Ratuszna, Alicja; Ossowski, Jerzy; Su?kowski, Wies?aw W.

80

Determination of benzene, toluene and N-hexane in urine and blood by headspace solid-phase microextration/gas-chromatography for the biomonitoring of occupational exposure  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A análise de tolueno, benzeno e n-hexano inalterados em urina e sangue humano é uma ferramenta para avaliar a exposição ocupacional a esses solventes. Um método simples usando microextração em fase sólida acoplada ao headspace (HS-SPME), usando fibras de carboxeno/polidimetilsiloxano (CAR-PDMS) e PDMS, para análise simultânea por cromatografia gasosa de tolueno, benzeno e n-hexano em urina e em sangue foi desenvolvido com intuito de realizar a monitorização bi (more) ológica de indivíduos expostos ocupacionalmente a esses solventes. O método foi aplicado na análise de amostras de trabalhadores que utilizavam colas, contendo solventes, na recuperação de calçados. O tolueno foi detectado em todas as amostras de sangue coletadas em sapatarias quando se utilizou a fibra de CAR-PDMS (16,0-55,2 ?g L-1, n=7) e o n-hexano foi detectado em duas amostras (33,0 and 41,3 ?g L-1). O benzeno não foi detectado em nenhuma das amostras de sangue e/ou urina. Nenhum dos solventes pode ser quantificado nas amostras de urina. Abstract in english Analysis of unchanged toluene, benzene and n-hexane in human blood and urine can be useful to evaluate occupational exposure to these solvents. A simple method was developed using headspace-solid phase microextraction (HS-SPME) for simultaneous gas-chromatography analysis of toluene, benzene and n-hexane in urine and blood; with purpose of biological monitoring of occupational exposure. Carboxen/polidimethylsiloxane fiber (CAR-PDMS) and PDMS fiber coating were employed in (more) this analysis. Blood and urine samples were collected from handling glue workers. The toluene was detected in all blood samples collected from workers handling glue in shoe repair shops, when using CAR-PDMS fibers (16.0-55.2 ?g L-1, n=7). n-Hexane was only detected in two blood samples (33.0 and 41.3 ?g L-1) and benzene was not detected in anyone. No solvent could be quantified in urine samples.

Gomes, Paulo C. F. de Lima; D'Andrea, Éverton D.; Mendes, Camila B.; Siqueira, Maria Elisa P. B. de

2010-01-01

 
 
 
 
81

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)

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. PMID:17208366

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

2006-12-10

82

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

UK PubMed Central (United Kingdom)

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.

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

2007-07-01

83

Headspace solid-phase microextraction (HS-SPME) for the determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in foundry molding sand  

Energy Technology Data Exchange (ETDEWEB)

The use of headspace solid-phase microextraction (HS-SPME) to determine benzene, toluene, ethylbenzene, and xylenes (BTEX) in foundry molding sand, specifically a 'green sand' (clay-bonded sand) was investigated. The BTEX extraction was conducted using a 75 {mu} M carboxen-polydimethylsiloxane (CAR-PDMS) fiber, which was suspended above 10 g of sample. The SPME fiber was desorbed in a gas chromatograph injector port (280{sup o}C for 1 min) and the analytes were characterized by mass spectrometry. The effects of extraction time and temperature, water content, and clay and bituminous coal percentage on HS-SPME of BTEX were investigated. Because green sands contain bentonite clay and carbonaceous material such as crushed bituminous coal, a matrix effect was observed. The detection limits for BTEX were determined to be {lt}= 0.18 ng g{sup -1} of green sand.

Dungan, R.S. [USDA ARS, Beltsville, MD (United States). Environmental Management & Byproducts Utilization Laboratory

2005-07-01

84

Comparative genomic analysis and benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) degradation pathways of Pseudoxanthomonas spadix BD-a59.  

Science.gov (United States)

Pseudoxanthomonas spadix BD-a59, isolated from gasoline-contaminated soil, has the ability to degrade all six BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylene) compounds. The genomic features of strain BD-a59 were analyzed bioinformatically and compared with those of another fully sequenced Pseudoxanthomonas strain, P. suwonensis 11-1, which was isolated from cotton waste compost. The genome of strain BD-a59 differed from that of strain 11-1 in many characteristics, including the number of rRNA operons, dioxygenases, monooxygenases, genomic islands (GIs), and heavy metal resistance genes. A high abundance of phage integrases and GIs and the patterns in several other genetic measures (e.g., GC content, GC skew, Karlin signature, and clustered regularly interspaced short palindromic repeat [CRISPR] gene homology) indicated that strain BD-a59's genomic architecture may have been altered through horizontal gene transfers (HGT), phage attack, and genetic reshuffling during its evolutionary history. The genes for benzene/toluene, ethylbenzene, and xylene degradations were encoded on GI-9, -13, and -21, respectively, which suggests that they may have been acquired by HGT. We used bioinformatics to predict the biodegradation pathways of the six BTEX compounds, and these pathways were proved experimentally through the analysis of the intermediates of each BTEX compound using a gas chromatograph and mass spectrometry (GC-MS). The elevated abundances of dioxygenases, monooxygenases, and rRNA operons in strain BD-a59 (relative to strain 11-1), as well as other genomic characteristics, likely confer traits that enhance ecological fitness by enabling strain BD-a59 to degrade hydrocarbons in the soil environment. PMID:23160122

Choi, Eun Jin; Jin, Hyun Mi; Lee, Seung Hyeon; Math, Renukaradhya K; Madsen, Eugene L; Jeon, Che Ok

2012-11-16

85

The effect of water presence on the photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene in the gas-phase  

Science.gov (United States)

In the present work, the gas-solid heterogeneous photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene (BTEX) over UV-irradiated titanium dioxide was studied in an annular reactor operated in the CSTR (continuous stirred-tank reactor) mode. GC-FID and GC-MS were used for analysing reactor inlet and outlet streams. Initial BTEX concentrations were in the low parts per million (ppmv) range, whereas the water concentration was in the range of 0-35,230 ppmv and the residence time varied from 50 to 210 s. The effect of water addition on the photocatalytic process showed strong dependence on the type of the BTEX and the water vapour concentration. The increase in residence time resulted in a considerable increase in the conversion achieved for all compounds and experimental conditions. There was a clear interaction between residence time and water presence regarding the effect on conversions achieved. It was established that conversions over 95% could be achieved by adjusting appropriately the experimental conditions and especially the water concentration in the reactor. In all cases, no by-products were detected above the detection limit and carbon dioxide was the only compound detected. Finally, various Langmuir-Hinshelwood kinetic models have been tested in the analysis of the experimental data obtained. The kinetic data obtained confirmed that water had an active participation in the photocatalytic reactions of benzene, toluene, ethylbenzene and m-xylene since the model involving reaction of BTEX and water adsorbed on different active sites yielded the most successful fitting to the experimental results for the first three compounds, whereas the kinetic model based on the assumption that reaction between VOC and water dissociatively adsorbed on the photocatalyst takes place was the most appropriate in the case of m-xylene.

Korologos, Christos A.; Philippopoulos, Constantine J.; Poulopoulos, Stavros G.

2011-12-01

86

Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils.  

UK PubMed Central (United Kingdom)

A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 ?g kg(-1) range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.

Zhou YY; Yu JF; Yan ZG; Zhang CY; Xie YB; Ma LQ; Gu QB; Li FS

2013-04-01

87

Degradation of benzene, toluene, and xylene isomers by a bacterial consortium obtained from rhizosphere soil of Cyperus sp. grown in a petroleum-contaminated area.  

UK PubMed Central (United Kingdom)

Increasing contamination of soil and groundwater with benzene, toluene, and xylene (BTX) due to activities of the chemical and oil refinery industry has caused serious environmental damage. Efficient methods are required to isolate and degrade them. Microorganisms associated with rhizosphere soil are considered efficient agents to remediate hydrocarbon contamination. In this study, we obtained a stabilized bacterial consortium from the rhizosphere soil of Cyperus sp. grown in a petroleum-contaminated field in Southern Mexico. This consortium was able to completely degrade BTX in 14 days. Bacteria isolated from the consortium were identified by 16S rRNA gene sequence analysis as Ralstonia insidiosa, Cellulomonas hominis, Burkholderia kururiensis, and Serratia marcescens. The BTX-degradation capacity of the bacterial consortium was confirmed by the detection of genes pheA, todC1, and xylM, which encoded phenol hydroxylase, toluene 1,2-dioxygenase, and xylene monooxygenase, respectively. Our results demonstrate feasibility of BTX biodegradation by indigenous bacteria that might be used for soil remediation in Southern Mexico.

Ortega-González DK; Zaragoza D; Aguirre-Garrido J; Ramírez-Saad H; Hernández-Rodríguez C; Jan-Roblero J

2013-04-01

88

Deuterium and tritium labelling of aromatic hydrocarbons by zeolite-catalysed exchange with perdeuteriobenzene, tritiated benzene, and [p-3H]toluene  

International Nuclear Information System (INIS)

[en] Three hydrogen zeolites, HNaY, H-Mordenite, and HZSM-5, have been employed as catalysts for hydrogen isotope exchange reactions. The zeolites catalysed exchange between the isotope sources perdeuteriobenzene, tritiated benzene, and [p-3H]toluene, and a wide range of organic substrates, thus providing a useful labelling technique. The extent and orientation of exchange in reaction products were assessed through the techniques of radio-gas chromatography, mass spectrometry, and 3H n.m.r. spectroscopy. Substituted benzenoid compounds were non-specifically labelled in the aromatic centres at temperatures from 40 to 175 deg C, but heterocyclic compounds and alkanes were not exchanged. A series of competitive exchange experiments gave an insight into the reasons for the lack of reactivity of some substrates. Inspection of the multiple exchange parameters and relative rates of exchange of substrates of different bulk suggested correlations between zeolite pore sizes, substrate reactivity, and labelling patterns. Consideration of these experimental results together with those from redistribution reactions with [p-3H]toluene led to interpretation of results in terms of acid exchange mechanisms, where these mechanisms are mediated by the constraints of zeolite pore geometry. (author)

1984-01-01

89

Degradation of benzene, toluene, and xylene isomers by a bacterial consortium obtained from rhizosphere soil of Cyperus sp. grown in a petroleum-contaminated area.  

Science.gov (United States)

Increasing contamination of soil and groundwater with benzene, toluene, and xylene (BTX) due to activities of the chemical and oil refinery industry has caused serious environmental damage. Efficient methods are required to isolate and degrade them. Microorganisms associated with rhizosphere soil are considered efficient agents to remediate hydrocarbon contamination. In this study, we obtained a stabilized bacterial consortium from the rhizosphere soil of Cyperus sp. grown in a petroleum-contaminated field in Southern Mexico. This consortium was able to completely degrade BTX in 14 days. Bacteria isolated from the consortium were identified by 16S rRNA gene sequence analysis as Ralstonia insidiosa, Cellulomonas hominis, Burkholderia kururiensis, and Serratia marcescens. The BTX-degradation capacity of the bacterial consortium was confirmed by the detection of genes pheA, todC1, and xylM, which encoded phenol hydroxylase, toluene 1,2-dioxygenase, and xylene monooxygenase, respectively. Our results demonstrate feasibility of BTX biodegradation by indigenous bacteria that might be used for soil remediation in Southern Mexico. PMID:23564628

Ortega-González, Diana Katherine; Zaragoza, Diego; Aguirre-Garrido, José; Ramírez-Saad, Hugo; Hernández-Rodríguez, César; Jan-Roblero, Janet

2013-04-07

90

Exploring the C-X…? halogen bonding motif: an infrared and Raman study of the complexes of CF?X (X = Cl, Br and I) with the aromatic model compounds benzene and toluene.  

UK PubMed Central (United Kingdom)

The formation of halogen bonded complexes formed between the trifluorohalomethanes CF?Cl, CF?Br and CF?I 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 CF?Br and CF?I substantial fractions of the monomers can be involved in 1:1 complexes. In addition, weak absorptions illustrating the formation of 2:1 complexes between CF?I 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 CF?Br.benzene, CF?I.benzene and (CF?I)?.benzene are -6.5(3), -7.6(2) and -14.5(9) kJ mol?¹. The values for CF?Br.toluene and CF?I.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···? halogen bonded complexes involving unsaturated Lewis bases such as ethene and ethyne.

Nagels N; Hauchecorne D; Herrebout WA

2013-01-01

91

Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline.  

UK PubMed Central (United Kingdom)

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach.

Kütt A; Movchun V; Rodima T; Dansauer T; Rusanov EB; Leito I; Kaljurand I; Koppel J; Pihl V; Koppel I; Ovsjannikov G; Toom L; Mishima M; Medebielle M; Lork E; Röschenthaler GV; Koppel IA; Kolomeitsev AA

2008-04-01

92

Separation of benzene from alkanes using 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid at several temperatures and atmospheric pressure: Effect of the size of the aliphatic hydrocarbons  

International Nuclear Information System (INIS)

The ionic liquid 1-ethyl-3-methylpyridinium ethylsulfate, [EMpy][ESO4], was studied for the separation of benzene from aliphatic hydrocarbons (octane or nonane) by solvent extraction through the determination of the (liquid + liquid) equilibrium (LLE) of the ternary systems: {octane (1) + benzene (2) + [EMpy][ESO4] (3)} and {nonane (1) + benzene (2) + [EMpy][ESO4] (3)} at T = (283.15 and 298.15) K and atmospheric pressure. Binodal curves were determined using the 'cloud point' method, and tie-line compositions were obtained by density measurements. The values of selectivity and distribution coefficient, derived from the tie-line data, were used to decide if this ionic liquid can be used as potential solvent for the separation of benzene from aliphatic hydrocarbons using liquid extraction. These results were analyzed and compared to those previously reported for the systems {hexane + benzene + [EMpy][ESO4]} and {heptane + benzene + [EMpy][ESO4]}. The experimental results show that this ionic liquid is suitable for the extraction of benzene from mixtures containing octane and nonane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations. The experimental results for the ternary systems were well correlated with the NRTL model. No literature data were found for the mixtures discussed in this paper.

2010-01-01

93

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)

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)

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

2008-07-01

94

Gas-phase reaction of daughter ions from the decay of multitritiated propane with benzene and toluene. Solution of a longstanding anomaly  

International Nuclear Information System (INIS)

The population of the daughter ions from the decay of multitritiated propane has been sampled by using as a probe their gas-phase reactions with benzene and toluene at pressures up to 400 torr. Tritiated n- and isopropylated arenes account together for 70 to 75% of the total activity of the decay ions. This observation - and the failure to detect aromatic allylation - removes an early radiochemical anomaly, by showing that decay of tritiated propane yields propyl ions as the most abundant daughter species, following a trend established for all other tritiated hydrocarbons. The abnormally high abundance of allyl ions measured by mass spectrometry is traced to the decomposition C3H7+ ? C3H5 + H2 allowed by its low activation energy, the lack of collisional stabilization, and the long residence time which characterizes operation of a charge mass spectrometer. The excitation energy required for the decomposition is likely to arise from the deformation energy of the propyl cations, born from the sudden nuclear transition in a shape reminiscent of the parent hydrocarbon molecule.

1982-01-01

95

Gas-phase reaction of daughter ions from the decay of multitritiated propane with benzene and toluene. Solution of a longstanding anomaly  

Energy Technology Data Exchange (ETDEWEB)

The population of the daughter ions from the decay of multitritiated propane has been sampled by using as a probe their gas-phase reactions with benzene and toluene at pressures up to 400 torr. Tritiated n- and isopropylated arenes account together for 70 to 75% of the total activity of the decay ions. This observation - and the failure to detect aromatic allylation - removes an early radiochemical anomaly, by showing that decay of tritiated propane yields propyl ions as the most abundant daughter species, following a trend established for all other tritiated hydrocarbons. The abnormally high abundance of allyl ions measured by mass spectrometry is traced to the decomposition C/sub 3/H/sub 7//sup +/ ..-->.. C/sub 3/H/sub 5/ + H/sub 2/ allowed by its low activation energy, the lack of collisional stabilization, and the long residence time which characterizes operation of a charge mass spectrometer. The excitation energy required for the decomposition is likely to arise from the deformation energy of the propyl cations, born from the sudden nuclear transition in a shape reminiscent of the parent hydrocarbon molecule.

Cacace, F. (Univ. of Rome, Italy); Cipollini, R.; Giacomello, P.

1982-05-27

96

Detection of the gasoline components methyl tert-butyl ether, benzene, toluene, and m-xylene using ion mobility spectrometers with a radioactive and UV ionization source.  

Science.gov (United States)

For the first time, ion mobility spectrometers (IMS) with radioactive and UV ionization sources in combination with multicapillary columns (MCCs) have been used to determine methyl tert-butyl ether (MTBE), a gasoline additive, in water and nitrogen as well as the monoaromatic compounds benzene, toluene, and m-xylene (BTX). A membrane extraction unit was set up to extract the substances from water, which is simple, effective, and easy to automate for further applications. Thus, the detection of MTBE and BTX of gasoline vapors was accomplished after a preliminary silicone membrane extraction. Two-dimensional data analyses of IMS-chromatograms allow us to separate these substances clearly according to their different retention and drift times. Method detection limits for MTBE were 2 microg/L (UV) and 30 pg/L (63Ni) in nitrogen and 20 mg/L (UV) and 1 microg/L (63Ni) in water. Rather a good reproducibility was achieved with relative standard deviations of between 2.9 and 9%. The method presented in this article has been proven to be suitable for nearly real-time monitoring as the total analysis time is less than 90 s. As an example of application, the detection of MTBE and BTX in a mixture of volatile organic compounds of pure gasoline using the 2-D IMS-chromatogram is presented. PMID:12659213

Baumbach, Jörg Ingo; Sielemann, Stefanie; Xie, Zhiyong; Schmidt, Hartwig

2003-03-15

97

Detection of the gasoline components methyl tert-butyl ether, benzene, toluene, and m-xylene using ion mobility spectrometers with a radioactive and UV ionization source.  

UK PubMed Central (United Kingdom)

For the first time, ion mobility spectrometers (IMS) with radioactive and UV ionization sources in combination with multicapillary columns (MCCs) have been used to determine methyl tert-butyl ether (MTBE), a gasoline additive, in water and nitrogen as well as the monoaromatic compounds benzene, toluene, and m-xylene (BTX). A membrane extraction unit was set up to extract the substances from water, which is simple, effective, and easy to automate for further applications. Thus, the detection of MTBE and BTX of gasoline vapors was accomplished after a preliminary silicone membrane extraction. Two-dimensional data analyses of IMS-chromatograms allow us to separate these substances clearly according to their different retention and drift times. Method detection limits for MTBE were 2 microg/L (UV) and 30 pg/L (63Ni) in nitrogen and 20 mg/L (UV) and 1 microg/L (63Ni) in water. Rather a good reproducibility was achieved with relative standard deviations of between 2.9 and 9%. The method presented in this article has been proven to be suitable for nearly real-time monitoring as the total analysis time is less than 90 s. As an example of application, the detection of MTBE and BTX in a mixture of volatile organic compounds of pure gasoline using the 2-D IMS-chromatogram is presented.

Baumbach JI; Sielemann S; Xie Z; Schmidt H

2003-03-01

98

Effect of switching gas inlet position on the performance of a polyurethane biofilter under transient loading for the removal of benzene, toluene and xylene mixtures.  

UK PubMed Central (United Kingdom)

The performance of a polyurethane (PU) biofilter was evaluated using different operating modes (unidirectional flow (UF) and flow-directional switching (FDS) operations) under transient loading conditions (intermittent and shutdown). Gas mixtures containing benzene, toluene and xylene (BTX) were employed as model gases. Quantitative real-time PCR methods were used for targeting the tmoA gene responsible for BTX degradation and estimating density of the BTX-degraders in the PU filter bed. Although the overall BTX Removal efficiencies at the outlet (50 h(-1) of space velocity) were similar between the UF and FDS biofilters, the removability of BTX in the FDS biofilter was higher than that in the UF biofilter until the 3rd sampling position (68 h(-1) of space velocity). The BTX removal potentials and tmoA gene copy numbers of the FDS biofilter remained constant, irrespective of the distances from the inlet, but those of the UF biofilter increased with increasing distance from the inlet position. These results indicate that an even distribution of BTX degraders in the FDS filter bed contributed to better BTX removal performance. After a 10 day-shutdown, the performances of the UF and SDF biofilters were rapidly restored within 1 day.

Lee EH; Ryu HW; Cho KS

2011-01-01

99

Effect of isobutanol on toluene biodegradation in nitrate amended, sulfate amended and methanogenic enrichment microcosms.  

UK PubMed Central (United Kingdom)

Isobutanol is an alternate fuel additive that is being considered because of economic and lower emission benefits. However, future gasoline spills could result in co-contamination of isobutanol with gasoline components such as benzene, toluene, ethyl-benzene and xylene. Hence, isobutanol could affect the degradability of gasoline components thereby having an effect on contaminant plume length and half-life. In this study, the effect of isobutanol on the biodegradation of a model gasoline component (toluene) was examined in laboratory microcosms. For this, toluene and isobutanol were added to six different toluene degrading laboratory microcosms under sulfate amended, nitrate amended or methanogenic conditions. While toluene biodegradation was not greatly affected in the presence of isobutanol in five out of the six different experimental sets, toluene degradation was completely inhibited in one set of microcosms. This inhibition occurred in sulfate amended microcosms constructed with inocula from wastewater treatment plant activated sludge. Our data suggest that toluene degrading consortia are affected differently by isobutanol addition. These results indicate that, if co-contamination occurs, in some cases the in situ half-life of toluene could be significantly extended.

Jayamani I; Cupples AM

2013-09-01

100

Effect of isobutanol on toluene biodegradation in nitrate amended, sulfate amended and methanogenic enrichment microcosms.  

Science.gov (United States)

Isobutanol is an alternate fuel additive that is being considered because of economic and lower emission benefits. However, future gasoline spills could result in co-contamination of isobutanol with gasoline components such as benzene, toluene, ethyl-benzene and xylene. Hence, isobutanol could affect the degradability of gasoline components thereby having an effect on contaminant plume length and half-life. In this study, the effect of isobutanol on the biodegradation of a model gasoline component (toluene) was examined in laboratory microcosms. For this, toluene and isobutanol were added to six different toluene degrading laboratory microcosms under sulfate amended, nitrate amended or methanogenic conditions. While toluene biodegradation was not greatly affected in the presence of isobutanol in five out of the six different experimental sets, toluene degradation was completely inhibited in one set of microcosms. This inhibition occurred in sulfate amended microcosms constructed with inocula from wastewater treatment plant activated sludge. Our data suggest that toluene degrading consortia are affected differently by isobutanol addition. These results indicate that, if co-contamination occurs, in some cases the in situ half-life of toluene could be significantly extended. PMID:23224907

Jayamani, Indumathy; Cupples, Alison M

2012-12-09

 
 
 
 
101

Ultrasonic-assisted drop-to-drop solvent microextraction in a capillary tube for analyzing trace benzene, toluene, xylene in one drop of a water sample  

Energy Technology Data Exchange (ETDEWEB)

A novel analytical technique termed ultrasonic-assisted drop-to-drop solvent microextraction (USA-DDSME) in a capillary tube was developed to determine trace benzene, toluene, xylene in one drop of a water sample, which was combined with gas chromatography-flame ionization detection (GC-FID). The advantages of this method are rapidity, convenience, ease of operation, simplicity of the device, and extremely little solvent and sample consumption. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, the volume of sample, extraction time and effect of salt concentration were optimized. The best optimum parameters for extraction were achieved with 3 {mu}L of extraction solvent. Chloroform was divided into four equal divisions in 20 {mu}L water sample (without salt addition) in a capillary tube and ultrasonicated for 10 min, centrifugalized at 2,500 rpm for 5 min to let the extraction solvent settle at the bottom of the capillary tube, then 1 {mu}L of the separated extraction solvent was injected into the GC-FID for analysis. Linearity of the method was determined by analyzing spiked water samples over a concentration range of 0.1-50 {mu}g mL{sup -1}. Correspondingly, the LOD values were 0.01 {mu}g mL{sup -1}. All calibration curves were found to have good linearity with correlation coefficients (r{sup 2}) > 0.995. The precision (RSD) of the system, measured by six repeated determinations of the analytes at 1 {mu}g mL{sup -1} were in the range of 1.6-3.5%. (orig.)

Zhang, Maosheng; Wu, Lijuan [Zhangzhou Normal Univ. (China). Dept. of Chemistry and Environmental Science; Fujian Province Univ. (China). Key Lab. of Analytical Science; Huang, Jiarong [Zhangzhou Entry-Exit Inspection and Quarantine Bureau (China); Zheng, Xianghua [Xiamen Entry-Exit Inspection and Quarantine Bureau (China). Inspection and Quarantine Technical Center

2010-12-15

102

Benzene, toluene and xylene biodegradation by Pseudomonas putida CCMI 852 Biodegradação de benzeno, tolueno e xileno pela Pseudomonas putida CCMI 852  

Directory of Open Access Journals (Sweden)

Full Text Available A minimal liquid medium containing benzene (B), toluene (T) and xylene (X) and mixtures thereof, was used to evaluate degradation activity of Pseudomonas putida CCMI 852 containing a TOL plasmid. Experiments were developed with B, T and X (100 mg L-1), with mixtures of BT, BX, and TX (50 + 50 mg L-1 each) and BTX (33.3 + 33.3 + 33.3 mg L-1 each), added to 500 mL of medium. After 18 to 24 hours, the inoculum was added and solvent disappearance was determined after 24 to 25 hours by GC. Results showed that P. putida CCMI 852 was able to metabolize T and X, but B was not metabolized. In a BTX mixture, B was not metabolized and T and X degradation rate decreased 50%.Meio mineral líquido contendo benzeno (B) ou tolueno (T) ou xileno (X) a 100 mg L-1 e suas misturas de BT, BX e TX (50 + 50 mg L-1 cada mistura) e BTX (33,3 + 33,3 + 33,3 mg L-1 cada mistura) foram utilizados para avaliar a atividade de degradação de B, T e X por Pseudomonas putida CCMI 852 contendo um plasmídeo TOL. Após 18 a 24 horas de homogenização da mistura, o inoculo foi adicionado e o decréscimo da concentração dos solventes foi determinado entre 24 e 25 horas por GC. Pseudomonas putida CCMI 852 foi capaz de metabolizar T e X, mas não B. Na mistura BTX, B não foi metabolizado também e a velocidade de degradação de T e X decresceu cerca de 50% comparado com soluções contendo apenas T ou X.

Marcelo Henrique Otenio; Maria Teresa Lopes da Silva; Maria Luiza Oliveira Marques; José Carlos Roseiro; Ederio Dino Bidoia

2005-01-01

103

Benzene, toluene and xylene biodegradation by Pseudomonas putida CCMI 852/ Biodegradação de benzeno, tolueno e xileno pela Pseudomonas putida CCMI 852  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Meio mineral líquido contendo benzeno (B) ou tolueno (T) ou xileno (X) a 100 mg L-1 e suas misturas de BT, BX e TX (50 + 50 mg L-1 cada mistura) e BTX (33,3 + 33,3 + 33,3 mg L-1 cada mistura) foram utilizados para avaliar a atividade de degradação de B, T e X por Pseudomonas putida CCMI 852 contendo um plasmídeo TOL. Após 18 a 24 horas de homogenização da mistura, o inoculo foi adicionado e o decréscimo da concentração dos solventes foi determinado entre 24 e 25 (more) horas por GC. Pseudomonas putida CCMI 852 foi capaz de metabolizar T e X, mas não B. Na mistura BTX, B não foi metabolizado também e a velocidade de degradação de T e X decresceu cerca de 50% comparado com soluções contendo apenas T ou X. Abstract in english A minimal liquid medium containing benzene (B), toluene (T) and xylene (X) and mixtures thereof, was used to evaluate degradation activity of Pseudomonas putida CCMI 852 containing a TOL plasmid. Experiments were developed with B, T and X (100 mg L-1), with mixtures of BT, BX, and TX (50 + 50 mg L-1 each) and BTX (33.3 + 33.3 + 33.3 mg L-1 each), added to 500 mL of medium. After 18 to 24 hours, the inoculum was added and solvent disappearance was determined after 24 to 25 (more) hours by GC. Results showed that P. putida CCMI 852 was able to metabolize T and X, but B was not metabolized. In a BTX mixture, B was not metabolized and T and X degradation rate decreased 50%.

Otenio, Marcelo Henrique; Silva, Maria Teresa Lopes da; Marques, Maria Luiza Oliveira; Roseiro, José Carlos; Bidoia, Ederio Dino

2005-09-01

104

Volumetric Properties of the Mixture Ethyl propenoate C5H8O2 + C6H6 Benzene (VMSD1212, LB4430_V)  

Science.gov (United States)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethyl propenoate C5H8O2 + C6H6 Benzene (VMSD1212, LB4430_V)' providing data by calculation of molar excess volume from low-pressure density measurements at variable mole fraction and constant temperature.

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

105

Volumetric Properties of the Mixture Ethyl propenoate C5H8O2 + C6H6 Benzene (VMSD1111, LB4426_V)  

Science.gov (United States)

This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture Ethyl propenoate C5H8O2 + C6H6 Benzene (VMSD1111, LB4426_V)' providing data from direct low-pressure measurement of mass density at variable mole fraction and constant temperature, in the single-phase region(s).

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

106

threo-Diethyl 2-ethyl-2-hy­droxy-3-(4-methyl­benzene­sulfonamido)­succinate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The asymmetric unit of the title compound, C17H25NO7S, contains two independent mol­ecules, which are enanti­omers forming a hydrogen-bonded dimer associated with two R 2 2(7) patterns. In each mol­ecule, one ethyl group from the two available ethyl ester functional gro...

Mekki, Sofiane; Rolland, Valérie; van Lee, Arie; Rolland, Marc

107

threo-Diethyl 2-ethyl-2-hy-droxy-3-(4-methyl-benzene-sulfonamido)-succinate.  

UK PubMed Central (United Kingdom)

The asymmetric unit of the title compound, C(17)H(25)NO(7)S, contains two independent mol-ecules, which are enanti-omers forming a hydrogen-bonded dimer associated with two R(2) (2)(7) patterns. In each mol-ecule, one ethyl group from the two available ethyl ester functional groups is disordered. In one mol-ecule, the ethyl group of the ester function from an ?-carb-oxy-lic acid is positionally disordered over two sets of sites with occupancies of 0.66:0.34. In the second mol-ecule, it is the ethyl group in the ?-ester function that is disordered over two sets of sites with occupancies of 0.58:0.42.

Mekki S; Rolland V; van Lee A; Rolland M

2011-08-01

108

threo-Diethyl 2-ethyl-2-hy-droxy-3-(4-methyl-benzene-sulfonamido)-succinate.  

Science.gov (United States)

The asymmetric unit of the title compound, C(17)H(25)NO(7)S, contains two independent mol-ecules, which are enanti-omers forming a hydrogen-bonded dimer associated with two R(2) (2)(7) patterns. In each mol-ecule, one ethyl group from the two available ethyl ester functional groups is disordered. In one mol-ecule, the ethyl group of the ester function from an ?-carb-oxy-lic acid is positionally disordered over two sets of sites with occupancies of 0.66:0.34. In the second mol-ecule, it is the ethyl group in the ?-ester function that is disordered over two sets of sites with occupancies of 0.58:0.42. PMID:22247718

Mekki, Sofiane; Rolland, Valérie; van Lee, Arie; Rolland, Marc

2011-07-30

109

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)

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.

Flamys Lena do N. Silva; José Ribeiro dos Santos Jr.; José Machado Moita Neto; Rosa Lina G. do N. P. da Silva; Danilo Luiz Flumignan; José Eduardo de Oliveira

2009-01-01

110

Ethyl 3-[6-(4-meth-oxy-benzene-sulfon-amido)-2H-indazol-2-yl]propano-ate monohydrate.  

UK PubMed Central (United Kingdom)

In the title compound, C(19)H(21)N(3)O(5)S·H(2)O, the central indazole system is essentially planar (r.m.s. deviation = 0.012?Å), while both the benzene ring and the mean plane defined by the non-H atoms of the ethyl propionic ester unit (r.m.s. deviation = 0.087?Å) are nearly perpendicular to the indazole plane, as indicated by the dihedral angles of 82.45?(8) and 75.62?(8)°, respectively. Consequently, the mol-ecule adopts a U-shaped geometry. In the crystal, the water mol-ecule, which is linked to the indazole system by a strong O-H?N hydrogen bond, is also involved in two additional N-H?O and O-H?O inter-actions, which link the organic mol-ecules into chains along the b-axis direction.

Abbassi N; Rakib el M; Hannioui A; Saadi M; El Ammari L

2013-02-01

111

Method for producing benzene arenes from coarse benzene  

UK PubMed Central (United Kingdom)

A process for preparing benzene-series arylhydrocarbon from crude benzene includes such steps as proportionally adding common triplet oil, hydrorefining, fractionating, extracting in solvent, distilling and rectifying to obtain high-purity (more than 99.9%) benzene, toluene and xylene.

SHE XICHUN ZHU

112

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  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 the (more) se 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.

Silva, Flamys Lena do N.; Santos Jr., José Ribeiro dos; Moita Neto, José Machado; Silva, Rosa Lina G. do N. P. da; Flumignan, Danilo Luiz; Oliveira, José Eduardo de

2009-01-01

113

(Liquid + liquid) equilibria of three ternary systems: (heptane + benzene + N-formylmorpholine), (heptane + toluene + N-formylmorpholine), (heptane + xylene + N-formylmorpholine) from T = (298.15 to 353.15) K  

International Nuclear Information System (INIS)

(Liquid + liquid) equilibrium (LLE) data for ternary systems: (heptane + benzene + N-formylmorpholine), (heptane + toluene + N-formylmorpholine), and (heptane + xylene + N-formylmorpholine) have been determined experimentally at temperatures ranging from 298.15 K to 353.15 K. Complete phase diagrams were obtained by determining solubility and tie-line data. Tie-line compositions were correlated by Othmer-Tobias and Bachman methods. The universal quasichemical activity coefficient (UNIQUAC) and the non-random two liquids equation (NRTL) were used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data. It is found that UNIQUAC and NRTL used for LLE could provide a good correlation. Distribution coefficients, separation factors, and selectivity were evaluated for the immiscibility region.

2007-01-01

114

Consecutive reactions of aromatic-OH adducts with NO, NO2 and O2: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline  

Directory of Open Access Journals (Sweden)

Full Text Available Consecutive reactions of adducts, resulting from OH radicals and aromatics, with the tropospheric scavenger molecules O2, NO and NO2 have been studied for benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline by observing decays of OH at temperatures where the thermal back-decomposition to OH is faster than 3 s?1, typically between 300 and 340 K. The experimental technique was resonance fluorescence with flash photolysis of water as source of OH. Biexponential decays were observed in the presence of either O2 or NO, and triexponential decays were obtained in the presence of NO2. The kinetic analysis was performed by fitting the relevant rate constants of the reaction mechanism to whole sets of decays obtained at various concentrations of aromatic and scavenger. In the case of hexamethylbenzene, the biexponential decays suggest the existence of the ipso-adduct, and the slightly higher necessary temperatures show that it is even more stable. In addition, smog chamber experiments at O2 concentrations from atmospheric composition down to well below 100 ppm have been carried out for benzene, toluene and p-xylene. The drop of the effective rate constant of removal by OH occurs at reasonable O2 levels, given the FP/RF results. Comparison of the adduct reactivities shows for all aromatics of this study that the reaction with O2 predominates over that with NO2 under all tropospheric conditions, and that a reaction with NO may only occur after the reaction with O2.

R. Koch; R. Knispel; M. Elend; M. Siese; C. Zetzsch

2007-01-01

115

Benzene and superior counterpart; Benzene et homologues superieurs  

Energy Technology Data Exchange (ETDEWEB)

A century ago, the first case of purpura and acute anemia provoked by benzene was described. Afterwards, others important toxic effects in relation with the exposure to this solvent were known: medullar aplasia, acute leukemia,carcinogenesis. The chronic intoxication by benzene is called benzenism, the term of benzolism is devoted to the intoxication provoked by the mixture of benzene and superior counterparts: toluene, xylenes. (N.C.)

NONE

1998-07-01

116

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)

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)

Almeida, Kelly Cristina Santana de

2006-07-01

117

A simplified Quick, Easy, Cheap, Effective, Rugged and Safe approach for the determination of trihalomethanes and benzene, toluene, ethylbenzene and xylenes in soil matrices by fast gas chromatography with mass spectrometry detection.  

UK PubMed Central (United Kingdom)

A method based on simplified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction followed by large-injection volume-fast gas chromatography and mass spectrometry detection has been developed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) and BTEX (benzene, toluene, ethylbenzene and xylenes) in soil samples. The simplified version of QuEChERS used meets the requirements of the "green chemistry" and provides reliable results with high sample throughput, low solvent consumption, little labour and the use of materials commonly employed in laboratories. The GC device used is equipped with a programmable temperature vaporizer (PTV), with a liner packed with Tenax-TA(®). Using the solvent-vent mode, the PTV allows the injection of large volumes of sample, affording an improvement in the sensitivity of the method. The chromatographic conditions used here allowed the separation of the compounds in less than 5.50 min. Good linearity was obtained for all the target compounds, with highly satisfactory repeatability and reproducibility values. The limits of detection were in the 0.2 to 15 ?g kg(-1) range. The method was validated by the analysis of two certified reference materials.

García Pinto C; Herrero Martín S; Pérez Pavón JL; Moreno Cordero B

2011-03-01

118

A simplified Quick, Easy, Cheap, Effective, Rugged and Safe approach for the determination of trihalomethanes and benzene, toluene, ethylbenzene and xylenes in soil matrices by fast gas chromatography with mass spectrometry detection.  

Science.gov (United States)

A method based on simplified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction followed by large-injection volume-fast gas chromatography and mass spectrometry detection has been developed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) and BTEX (benzene, toluene, ethylbenzene and xylenes) in soil samples. The simplified version of QuEChERS used meets the requirements of the "green chemistry" and provides reliable results with high sample throughput, low solvent consumption, little labour and the use of materials commonly employed in laboratories. The GC device used is equipped with a programmable temperature vaporizer (PTV), with a liner packed with Tenax-TA(®). Using the solvent-vent mode, the PTV allows the injection of large volumes of sample, affording an improvement in the sensitivity of the method. The chromatographic conditions used here allowed the separation of the compounds in less than 5.50 min. Good linearity was obtained for all the target compounds, with highly satisfactory repeatability and reproducibility values. The limits of detection were in the 0.2 to 15 ?g kg(-1) range. The method was validated by the analysis of two certified reference materials. PMID:21338768

García Pinto, Carmelo; Herrero Martín, Sara; Pérez Pavón, José Luis; Moreno Cordero, Bernardo

2011-01-19

119

Influence of Soil Components on the Biodegradation of Benzene, Toluene, Ethylbenzene, and o-, m-, and p-Xylenes by the Newly Isolated Bacterium Pseudoxanthomonas spadix BD-a59 ?  

Science.gov (United States)

A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxanthomonas has not included any known BTEX degraders. The BTEX biodegradation rate was very low in MSB broth, but adding a small amount of yeast extract greatly enhanced the biodegradation. Interestingly, degradation occurred very quickly in slurry systems amended with sterile soil solids but not with aqueous soil extract. Moreover, if soil was combusted first to remove organic matter, the enhancement effect on BTEX biodegradation was lost, indicating that some components of insoluble organic compounds are nutritionally beneficial for BTEX degradation. Reverse transcriptase PCR-based analysis of field-fixed mRNA revealed expression of the tmoA gene, whose sequence was closely related to that carried by strain BD-a59. This study suggests that strain BD-a59 has the potential to assist in BTEX biodegradation at contaminated sites.

Kim, Jeong Myeong; Le, Ngoc Thuan; Chung, Bok Sil; Park, Jin Ho; Bae, Jin-Woo; Madsen, Eugene L.; Jeon, Che Ok

2008-01-01

120

Influence of soil components on the biodegradation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes by the newly isolated bacterium Pseudoxanthomonas spadix BD-a59.  

Science.gov (United States)

A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxanthomonas has not included any known BTEX degraders. The BTEX biodegradation rate was very low in MSB broth, but adding a small amount of yeast extract greatly enhanced the biodegradation. Interestingly, degradation occurred very quickly in slurry systems amended with sterile soil solids but not with aqueous soil extract. Moreover, if soil was combusted first to remove organic matter, the enhancement effect on BTEX biodegradation was lost, indicating that some components of insoluble organic compounds are nutritionally beneficial for BTEX degradation. Reverse transcriptase PCR-based analysis of field-fixed mRNA revealed expression of the tmoA gene, whose sequence was closely related to that carried by strain BD-a59. This study suggests that strain BD-a59 has the potential to assist in BTEX biodegradation at contaminated sites. PMID:18835999

Kim, Jeong Myeong; Le, Ngoc Thuan; Chung, Bok Sil; Park, Jin Ho; Bae, Jin-Woo; Madsen, Eugene L; Jeon, Che Ok

2008-10-03

 
 
 
 
121

Influence of soil components on the biodegradation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes by the newly isolated bacterium Pseudoxanthomonas spadix BD-a59.  

UK PubMed Central (United Kingdom)

A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxanthomonas has not included any known BTEX degraders. The BTEX biodegradation rate was very low in MSB broth, but adding a small amount of yeast extract greatly enhanced the biodegradation. Interestingly, degradation occurred very quickly in slurry systems amended with sterile soil solids but not with aqueous soil extract. Moreover, if soil was combusted first to remove organic matter, the enhancement effect on BTEX biodegradation was lost, indicating that some components of insoluble organic compounds are nutritionally beneficial for BTEX degradation. Reverse transcriptase PCR-based analysis of field-fixed mRNA revealed expression of the tmoA gene, whose sequence was closely related to that carried by strain BD-a59. This study suggests that strain BD-a59 has the potential to assist in BTEX biodegradation at contaminated sites.

Kim JM; Le NT; Chung BS; Park JH; Bae JW; Madsen EL; Jeon CO

2008-12-01

122

Toluene embryopathy  

Energy Technology Data Exchange (ETDEWEB)

Three children with microcephaly, central nervous system dysfunction, minor craniofacial and limb anomalies, and variable growth deficiency were born to women who inhaled large quantities of pure toluene throughout pregnancy. The features in there patients were reminiscent of the patterns of malformation previously described following in utero exposure to alcohol, certain anticonvulsants, and hyperphenylalaninemia. It is possible that there is a variable and nonspecific teratogenic phenotype characterized by alterations in growth, development, and morphogenesis. Careful evaluation and monitoring of infants exposed to toluene in utero are needed to determine the significance of these findings.

Hersh, J.H.; Podruch, P.E.; Rogers, G.; Weisskopf, B.

1985-06-01

123

Electrophilic mercuration and thallation of benzene and substituted benzenes in trifluoroacetic acid solution*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mercuration and thallation of benzene and substituted benzenes was studied with mercuric and thallic trifluoroacetate, respectively, in trifluoroacetic acid. With the shortest reaction time (1 sec) at 0°, the relative rate of mercuration of toluene compared to that of benzene was 17.5, with the ...

Olah, George A.; Hashimoto, Iwao; Lin, Henry C.

124

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

International Nuclear Information System (INIS)

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.

1994-01-01

125

Alteraciones hematológicas en trabajadores expuestos ocupacionalmente a mezcla de benceno- tolueno-xileno (BTX) en una fábrica de pinturas Blood disorders among workers exposed to a mixture of benzene-toluene-xylene (BTX) in a paint factory  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivos. Evaluar las tres series celulares sanguíneas e identificar la presencia de hipocromía, macrocitosis, leucopenia, linfocitopenia y trombocitopenia en un grupo de trabajadores expuestos a la mezcla de benceno-tolueno-xileno (BTX). Materiales y métodos. Estudio transversal donde se incluyó a 97 trabajadores de una empresa de pinturas de México a los que se les realizó una biometría hemática convencional y les fue estimada la exposición a través de la dosis diaria potencial acumulada para vapores de BTX. Resultados. Del total de trabajadores, 19,6%, mostró macrocitosis, 18,6%, linfocitopenia, 10,3% hipocromía, 7,2% trombocitopenia y 5,2% leucopenia. La asociación cruda de macrocitosis con exposición a dosis alta de mezcla de BTX fue la única significativa (OR:3,6; IC95%: 1,08 - 13,9; p=0,02) y en la que se estructuró un modelo de regresión logística (OR:6,7; IC95%: 1,33 - 13,55; p:0,02) ajustada por edad, consumo de alcohol y tabaquismo. Conclusiones. Todos los componentes citohemáticos analizados mostraron cambios leves; que podrían estar asociados con la exposición a la mezcla de BTX. De ellos, la macrocitosis podría constituirse en una manifestación precoz que merece ser vigilada.Objectives. Evaluate the three blood cell series and identify the presence of hypochromia, macrocytosis, leucopenia, lymphopenia, and thrombocytopenia in a group of workers exposed to the mixture of benzene-toluene-xylene (BTX). Materials and methods. A cross-sectional study which included 97 workers from a paint factory in Mexico. The participants underwent conventional blood count and tests for potential cumulative daily dose of BTX fumes, to estimate exposure. Results. From the total of workers, 19.6% showed macrocytosis, 18.6%, lymphopenia, hypochromia 10.3%, 7.2% and 5.2% thrombocytopenia leukopenia. The crude association of macrocytosis with exposure to high doses of BTX mixture was the only with statistical significance (OR: 3.6, 95% CI 1.08 to 13.9, P = 0.02), and the base for a logistic regression model (OR: 6.7, 95% CI 1.33 to 13.55, P = 0.02) adjusted for age, alcohol consumption, and smoking. Conclusions. All blood cytological components analyzed demonstrated mild changes, potentially associated with exposure to the mixture of BTX. Macrocytosis could constitute an early manifestation worthy for surveillance.

Luis Haro-García; Nadia Vélez-Zamora; Guadalupe Aguilar-Madrid; Susana Guerrero-Rivera; Vanessa Sánchez-Escalante; Sergio R. Muñoz; Edward Mezones-Holguín; Cuauhtémoc Juárez-Pérez

2012-01-01

126

Alteraciones hematológicas en trabajadores expuestos ocupacionalmente a mezcla de benceno- tolueno-xileno (BTX) en una fábrica de pinturas/ Blood disorders among workers exposed to a mixture of benzene-toluene-xylene (BTX) in a paint factory  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Objetivos. Evaluar las tres series celulares sanguíneas e identificar la presencia de hipocromía, macrocitosis, leucopenia, linfocitopenia y trombocitopenia en un grupo de trabajadores expuestos a la mezcla de benceno-tolueno-xileno (BTX). Materiales y métodos. Estudio transversal donde se incluyó a 97 trabajadores de una empresa de pinturas de México a los que se les realizó una biometría hemática convencional y les fue estimada la exposición a través de la dos (more) is diaria potencial acumulada para vapores de BTX. Resultados. Del total de trabajadores, 19,6%, mostró macrocitosis, 18,6%, linfocitopenia, 10,3% hipocromía, 7,2% trombocitopenia y 5,2% leucopenia. La asociación cruda de macrocitosis con exposición a dosis alta de mezcla de BTX fue la única significativa (OR:3,6; IC95%: 1,08 - 13,9; p=0,02) y en la que se estructuró un modelo de regresión logística (OR:6,7; IC95%: 1,33 - 13,55; p:0,02) ajustada por edad, consumo de alcohol y tabaquismo. Conclusiones. Todos los componentes citohemáticos analizados mostraron cambios leves; que podrían estar asociados con la exposición a la mezcla de BTX. De ellos, la macrocitosis podría constituirse en una manifestación precoz que merece ser vigilada. Abstract in english Objectives. Evaluate the three blood cell series and identify the presence of hypochromia, macrocytosis, leucopenia, lymphopenia, and thrombocytopenia in a group of workers exposed to the mixture of benzene-toluene-xylene (BTX). Materials and methods. A cross-sectional study which included 97 workers from a paint factory in Mexico. The participants underwent conventional blood count and tests for potential cumulative daily dose of BTX fumes, to estimate exposure. Results. (more) From the total of workers, 19.6% showed macrocytosis, 18.6%, lymphopenia, hypochromia 10.3%, 7.2% and 5.2% thrombocytopenia leukopenia. The crude association of macrocytosis with exposure to high doses of BTX mixture was the only with statistical significance (OR: 3.6, 95% CI 1.08 to 13.9, P = 0.02), and the base for a logistic regression model (OR: 6.7, 95% CI 1.33 to 13.55, P = 0.02) adjusted for age, alcohol consumption, and smoking. Conclusions. All blood cytological components analyzed demonstrated mild changes, potentially associated with exposure to the mixture of BTX. Macrocytosis could constitute an early manifestation worthy for surveillance.

Haro-García, Luis; Vélez-Zamora, Nadia; Aguilar-Madrid, Guadalupe; Guerrero-Rivera, Susana; Sánchez-Escalante, Vanessa; Muñoz, Sergio R.; Mezones-Holguín, Edward; Juárez-Pérez, Cuauhtémoc

2012-06-01

127

A solid phase microextraction coating based on ionic liquid sol-gel technique for determination of benzene, toluene, ethylbenzene and o-xylene in water samples using gas chromatography flame ionization detector.  

Science.gov (United States)

Ionic liquid mediated sol-gel sorbents for head-space solid phase microextraction (HS-SPME) were developed for the extraction of benzene, toluene, ethylbenzene and o-xylene (BTEX) compounds from water samples in ultra-trace levels. The analytes were subsequently analyzed with gas chromatography coupled to flame ionization detector (GC-FID). Three different coating fibers were prepared including: poly(dimethylsiloxane) (PDMS), coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a higher temperature than decomposition temperature of ionic liquid (PDMS-IL-HT) and coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a lower temperature than decomposition temperature of ionic liquid (PDMS-IL-LT). Prepared fibers demonstrate many advantages such as high thermal and chemical stabilities due to the chemical bonding of the coatings with the silanol groups on the fused-silica surface fiber. These fibers have shown long life time up to 180 extractions. The scanning electron micrographs of the fibers surfaces revealed that addition of ionic liquid into the sol solution during the sol-gel process increases the fiber coating thickness, affects the form of fiber structure and also leaves high pores in the fiber surface that cause high surface area and therefore increases sample capacity of the fibers. The important parameters that affect the extraction efficiency are desorption temperature and time, sample volume, extraction temperature, extraction time, stirring speed and salt effect. Therefore these factors were investigated and optimized. Under optimal conditions, the dynamic linear range with PDMS-IL-HT, PDMS and PDMS-IL-LT fibers were 0.3-200,000; 50-200,000 and 170-150,000pgmL(-1) and the detection limits (S/N=3) were 0.1-2 and 15-200 and 50-500pgmL(-1), and limit of quantifications (S/N=10) were 0.3-8 and 50-700 and 170-1800, respectively. The relative standard deviations (RSD) for one fiber (repeatability) (n=5), were obtained from 3.1 up to 5.4% and between fibers or batch to batch (reproducibility) (n=3) in the range of 3.8-8.5% for three fibers. The developed method was successfully applied to the real water samples while the relative recovery percentages obtained for the spiked water samples at 20pgmL(-1) were from 91.2 to 103.3%. PMID:23582769

Sarafraz-Yazdi, Ali; Vatani, Hossein

2013-03-26

128

Protein Engineering of Toluene Monooxygenases for Synthesis of Chiral Sulfoxides?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Enantiopure sulfoxides are valuable asymmetric starting materials and are important chiral auxiliaries in organic synthesis. Toluene monooxygenases (TMOs) have been shown previously to catalyze regioselective hydroxylation of substituted benzenes and phenols. Here we show that TMOs are also capable ...

Feingersch, Roi; Shainsky, Janna; Wood, Thomas K.; Fishman, Ayelet

129

Poly[[[[1-ethyl-6,8-difluoro-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylato]cadmium]-?-benzene-1,4-dicarboxylato] trihydrate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title layered coordination polymer, {[Cd(C17H18F2N3O3)(C8H4O4)]·3H2O}n, the CdII atom exhibits a very distorted CdO6 octahedral geometry defined by one O3,O4-bidentate 1-ethyl-6,8-difluoro-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylate (lome) ligand, one O,O?-bidentate benzene-1,4-dicarboxylate (bdc) dianion and two O-monodentate bdc dianions. Both the bdc species in the asymmetric unit are completed by crystallographic inversion symmetry. The bridging bdc dianions link the cadmium nodes into a rectangular grid lying parallel to (01overline{1}). A network of N—H...O and O—H...O hydrogen bonds helps to establish the packing.

Xin-Ping Kang; Zhe An; Rena Kasimu

2010-01-01

130

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate.  

UK PubMed Central (United Kingdom)

The catalyst-free multicomponent reaction of 1,2-diaminobenzene, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate forms pyrrolo[1,2-a]quinoxaline derivatives in good yields. Ethylenediamine also reacts under similar conditions to produce new pyrrolo[1,2-a]pyrazine derivatives.

Piltan M; Moradi L; Abasi G; Zarei SA

2013-01-01

131

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The catalyst-free multicomponent reaction of 1,2-diaminobenzene, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate forms pyrrolo[1,2-a]quinoxaline derivatives in good yields. Ethylenediamine also reacts under similar conditions to produce new pyrrolo[1,2-a]pyrazine derivatives.

Mohammad Piltan; Loghman Moradi; Golaleh Abasi; Seyed Amir Zarei

132

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate  

Directory of Open Access Journals (Sweden)

Full Text Available The catalyst-free multicomponent reaction of 1,2-diaminobenzene, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate forms pyrrolo[1,2-a]quinoxaline derivatives in good yields. Ethylenediamine also reacts under similar conditions to produce new pyrrolo[1,2-a]pyrazine derivatives.

Mohammad Piltan; Loghman Moradi; Golaleh Abasi; Seyed Amir Zarei

2013-01-01

133

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate.  

Science.gov (United States)

The catalyst-free multicomponent reaction of 1,2-diaminobenzene, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate forms pyrrolo[1,2-a]quinoxaline derivatives in good yields. Ethylenediamine also reacts under similar conditions to produce new pyrrolo[1,2-a]pyrazine derivatives. PMID:23616791

Piltan, Mohammad; Moradi, Loghman; Abasi, Golaleh; Zarei, Seyed Amir

2013-03-11

134

Electrophilic mercuration and thallation of benzene and substituted benzenes in trifluoroacetic acid solution.  

UK PubMed Central (United Kingdom)

The mercuration and thallation of benzene and substituted benzenes was studied with mercuric and thallic trifluoroacetate, respectively, in trifluoroacetic acid. With the shortest reaction time (1 sec) at 0 degrees , the relative rate of mercuration of toluene compared to that of benzene was 17.5, with the isomer distribution in toluene of: ortho, 17.4%; meta, 5.9%; and para, 76.7%. The isomer distribution in toluene varied with the reaction time, significantly more at 25 degrees than at 0 degrees . The competitive thallation of benzene and toluene with thallic trifluoroacetate in trifluoroacetic acid at 15 degrees showed the relative rate, toluene/benzene, to be 33, with the isomer distribution in toluene of: ortho, 9.5%; meta, 5.5%; and para, 85.0%. With increasingly higher reaction temperatures in both mercuration and thallation reactions of aromatics, isomerization (both intramolecular and intermolecular) within the relevant ortho- and para-metallated intermediate ions and/or of the isomers becomes more important. Competitive rates and isomer distributions of mercuration and thallation of benzene and substituted benzenes were also determined. The predominant para substitution in both mercuration and thallation of methylbenzenes reflects, besides some steric factors, the strong stabilizing effect of para methyl groups on the arenium ion intermediates. Under predominantly kinetically controlled conditions, no anomalous increase in the amount of meta substitution was observed.

Olah GA; Hashimoto I; Lin HC

1977-10-01

135

Comparação entre injeção na coluna ("on-column") e headspace dinâmico na determinação de benzeno, tolueno e xilenos (BTX) em amostras de água/ Comparison between on-column injection and dynamic headspace in the determination of Benzene, Toluene and Xylene (BTX) in water  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english The analysis of water samples containing volatile organic compounds has become an important task in analytical chemistry. Gas chromatography has been widely used for the analysis of volatile organic compounds in water. The headspace analysis shows as a principal characteristic the possibility of determination of the volatile components in drinking water. Benzene, Toluene and Xylene (BTX) are important compounds usually present in drinking water, from contamination by petr (more) oleum derivatives. Since they are toxic compounds even when present in low concentration levels, their determination is important in order to define the quality of the water. The sampling technique using headspace, coupled with gas chromatography as the separation method, showed to be suitable for BTX analysis in several samples at the mug/L (ppb) level.

Gobato, Elaine A. A. F.; Lanças, Fernando M.

2001-04-01

136

Poly(N,N'-dichloro-N-ethyl-benzene-1, 3-disulfonamide) and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide as novel catalytic reagents for synthesis of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl)methanes under solid-state, solvent and water conditions  

International Nuclear Information System (INIS)

Easy and rapid preparation of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl) methanes from indole with various aldehydes and ketones using poly (N,N'-dichloro-N-ethyl-benzene-1,3-disulfonamide) [PCBS] and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide [TCBDA] as novel catalysts under various conditions are here described. (author)

2010-01-01

137

Poly(N,N'-dichloro-N-ethyl-benzene-1, 3-disulfonamide) and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide as novel catalytic reagents for synthesis of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl)methanes under solid-state, solvent and water conditions  

Energy Technology Data Exchange (ETDEWEB)

Easy and rapid preparation of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl) methanes from indole with various aldehydes and ketones using poly (N,N'-dichloro-N-ethyl-benzene-1,3-disulfonamide) [PCBS] and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide [TCBDA] as novel catalysts under various conditions are here described. (author)

Ghorbani-Vaghei, Ramin [Bu-Ali Sina University, Hamadan (Iran, Islamic Republic of). Faculty of Chemistry. Dept. of Organic Chemistry; Veisi, Hojat [Payame Noor University, Songhor, Kermanshah (Iran, Islamic Republic of). Dept. of Chemistry

2010-07-01

138

Reducing benzene  

Energy Technology Data Exchange (ETDEWEB)

This article discusses the forms of benzene in desalter effluent brine and use of chemical treatments for benzene control in wastewaters from US refineries. The regulation of benzene emissions by the US Environmental Protection Agency (EPA), the imposition of total annual benzene (TAB) limits, and the use of source reduction as an alternative to remediation are considered along with the large contribution of desalting operations to the TAB for a refinery. The ability to chemically treat benzene in desalter effluent brine as an economic alternative to remediation is explored. The impact of obverse (water-in-oil) emulsions, reverse (oil in water) emulsions, colloidal solutions, and molecular solutions on the benzene in desalter brine is considered along with their chemical treatments. Two case studies of the reduction of benzene in effluent brine are presented with the dosages of chemicals used provided.

Moffitt, M.; Dion, M.; Hart, P. [BetzDearborn Inc. (United States)

2001-11-01

139

Anticonvulsant and antipunishment effects of toluene  

Energy Technology Data Exchange (ETDEWEB)

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, the authors first demonstrated that pretreatment of mice 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 of death after pentylenetetrazol injection in a manner related to the duration and concentration of exposure; at lower convulsant doses, inhalation of moderate concentrations (EC/sub 58/, 1300 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 in rats 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. 51 references, 3 figures, 2 tables.

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

1984-01-01

140

Dioxygenase-catalysed oxidation of disubstituted benzene substrates: benzylic monohydroxylation versus aryl cis-dihydroxylation and the meta effect.  

Science.gov (United States)

Biotransformations of a series of ortho-, meta- and para-substituted ethylbenzene and propylbenzene substrates have been carried out, using Pseudomonas putida UV4, a source of toluene dioxygenase (TDO). The ortho- and para-substituted alkylbenzene substrates yielded, exclusively, the corresponding enantiopure cis-dihydrodiols of the same absolute configuration. However, the meta isomers, generally, gave benzylic alcohol bioproducts, in addition to the cis-dihydrodiols (the meta effect). The benzylic alcohols were of identical (R) absolute configuration but enantiomeric excess values were variable. The similar (2R) absolute configurations of the cis-dihydrodiols are consistent with both the ethyl and propyl groups having dominant stereodirecting effects over the other substituents. The model used earlier, to predict the regio- and stereo-chemistry of cis-dihydrodiol bioproducts derived from substituted benzene substrates has been refined, to take account of non-symmetric substituents like ethyl or propyl groups. The formation of benzylic hydroxylation products, from meta-substituted benzene substrates, without further cis-dihydroxylation to yield triols provides a further example of the meta effect during toluene dioxygenase-catalysed oxidations. PMID:17036124

Boyd, Derek R; Sharma, Narain D; Bowers, Nigel I; Dalton, Howard; Garrett, Mark D; Harrison, John S; Sheldrake, Gary N

2006-07-31

 
 
 
 
141

Dioxygenase-catalysed oxidation of disubstituted benzene substrates: benzylic monohydroxylation versus aryl cis-dihydroxylation and the meta effect.  

UK PubMed Central (United Kingdom)

Biotransformations of a series of ortho-, meta- and para-substituted ethylbenzene and propylbenzene substrates have been carried out, using Pseudomonas putida UV4, a source of toluene dioxygenase (TDO). The ortho- and para-substituted alkylbenzene substrates yielded, exclusively, the corresponding enantiopure cis-dihydrodiols of the same absolute configuration. However, the meta isomers, generally, gave benzylic alcohol bioproducts, in addition to the cis-dihydrodiols (the meta effect). The benzylic alcohols were of identical (R) absolute configuration but enantiomeric excess values were variable. The similar (2R) absolute configurations of the cis-dihydrodiols are consistent with both the ethyl and propyl groups having dominant stereodirecting effects over the other substituents. The model used earlier, to predict the regio- and stereo-chemistry of cis-dihydrodiol bioproducts derived from substituted benzene substrates has been refined, to take account of non-symmetric substituents like ethyl or propyl groups. The formation of benzylic hydroxylation products, from meta-substituted benzene substrates, without further cis-dihydroxylation to yield triols provides a further example of the meta effect during toluene dioxygenase-catalysed oxidations.

Boyd DR; Sharma ND; Bowers NI; Dalton H; Garrett MD; Harrison JS; Sheldrake GN

2006-09-01

142

Stereospecific sulfoxidation by toluene and naphthalene dioxygenases.  

Science.gov (United States)

Studies on the sulfoxidation of aryl alkyl sulfides by purified toluene dioxygenase and naphthalene dioxygenase showed that naphthalene dioxygenase produces sulfoxides of (S) absolute configuration in high enantiomeric purity while those formed by toluene dioxygenase are of variable enantiomeric purity depending on the p-substituents on the benzene ring. Oxygen uptake experiments with naphthalene dioxygenase showed that the reaction rate and degree of oxygen incorporation are affected by both aryl and alkyl substituents. 18O2-Incorporation experiments showed that the oxygen atom of methyl phenyl sulfoxide formed by toluene dioxygenase and naphthalene dioxygenase is derived exclusively from O2. Accompanying studies showed that chloroperoxidase produces single (R)-sulfoxides (> 98% enantiomeric excess) from the aryl alkyl sulfides examined in the present study. PMID:7612022

Lee, K; Brand, J M; Gibson, D T

1995-07-01

143

Stereospecific sulfoxidation by toluene and naphthalene dioxygenases.  

UK PubMed Central (United Kingdom)

Studies on the sulfoxidation of aryl alkyl sulfides by purified toluene dioxygenase and naphthalene dioxygenase showed that naphthalene dioxygenase produces sulfoxides of (S) absolute configuration in high enantiomeric purity while those formed by toluene dioxygenase are of variable enantiomeric purity depending on the p-substituents on the benzene ring. Oxygen uptake experiments with naphthalene dioxygenase showed that the reaction rate and degree of oxygen incorporation are affected by both aryl and alkyl substituents. 18O2-Incorporation experiments showed that the oxygen atom of methyl phenyl sulfoxide formed by toluene dioxygenase and naphthalene dioxygenase is derived exclusively from O2. Accompanying studies showed that chloroperoxidase produces single (R)-sulfoxides (> 98% enantiomeric excess) from the aryl alkyl sulfides examined in the present study.

Lee K; Brand JM; Gibson DT

1995-07-01

144

Electron beam degradation of simulated toluene-containing exhaust gas  

International Nuclear Information System (INIS)

With toluene as an example, experimental investigation on VOCs treatment by electron beam irradiation was carried out. The system uses 0.8 MeV electron beams to irradiate simulated toluene-containing gases to 5kGy-40kGy for investigatiing effects of initial concentration, absorbed dose, humidity on toluene removal rate. The toluene removal rate increased with absorbed dose. With 0.5-l.2Nm3/h of the gas flow at an initial toluene concentration of 1600mg/Nm3, the toluene removal rate was 46.5% at 10kGy and 72.2% at 40kGy. And increasing humidity increased the toluene removal rate, too. Qualitative analysis on by-products of the toluene degradation was made by means of Gas Chromatogram-Mass Spectrometer (GC/MS) and Chromatography of Ions (IC). It was found that the by-products consist of mainly benzaldehyde and formic acid, plus a little benzoic acid, benzyl alcohol, methyl pyridine, nitrotoluene, o-cresol, phenol and benzoin ethyl etherl. Mechanisms of the E-beam toluene removal, i.e. the contributions of OH free radicals and O2 to the oxidation of toluene, were discussed. (authors)

2007-01-01

145

Cerebellar dysfunction caused by sniffing of toluene-containing thinner  

Energy Technology Data Exchange (ETDEWEB)

A 19-year-old man who had sniffed lacquer thinner for 8 months was found to suffer from cerebellar dysfunction and visual disorders. He had blurred vision, dysarthria, nystagmus, slight intention tremor, staggering gait and an abnormal EEG. The thinner contained 68% toluene, 18% ethyl acetate, 9% methyl isobutyl ketone (MIBK), 3% isopropyl alcohol (IPA) and 3% butyl acetate. The concentration of each solvent in the plastic bag used for sniffing was 12,000 ppm toluene, 11,500 ppm ethyl acetate, 6,000 ppm IPA and 2,000 ppm MIBK. Previously reported cerebellar dysfunction due to toluene or toluene-containing solvents are summarized and discussed. Based on these reports and the present case, toluene is presumed to impair function in the order of the vermis,cerebellar hemispheres, and cerebrum, when a relatively high concentration of toluene is inhaled. The effects of organic solvents, especially toluene, on the cerebellum are considered to be very important from the viewpoint of occupational health, since toluene is widely used in industry and many workers are exposed to it.

Takeuchi, Y. (Nagoya Univ. School of Medicine, Japan); Hisanaga, N.; Ono, Y.; Ogawa, T.; Hamaguchi, Y.; Okamoto, S.

1982-01-01

146

Health Aspects of Toluene and Xylene Exposures Associated with Motor Gasoline,  

Science.gov (United States)

In response to concerns that exposures to toluene and xylenes during the manufacture, distribution and use of motor gasolines may present similar risks to the potential blood and bone marrow abnormalities from over-exposure to benzene, the report reviews ...

A. R. Eyres

1987-01-01

147

Optimización de iones de fierro para la eliminación de piocianina en la reacción de degradación de Tolueno, Benceno y Fenol por Pseudomonas aeruginosa/ Optimization of iron ions to eliminate pyocyanine in the degradation reaction of Toluene, Benzene and Phenol by Pseudomonas aeruginosa  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Una amplia gama de substancias xenobióticas representan un serio problema como contaminantes ambientales por su toxicidad; entre ellos los compuestos aromáticos pueden ser biodegradados por microorganismos que los usan como fuente de carbono y energía. El género Pseudomonas destaca por sus múltiples aplicaciones biotecnológicas debido a su gran versatilidad metabólica; puede producir metabolitos útiles, transformaciones enzimáticas, biodegradación y biorremediac (more) ión de suelos, y en aguas contaminadas con petróleo y plaguicidas. En esta investigación se usaron células de P. aeruginosa para degradar tolueno, benceno y fenol. La cepa fue cultivada en medio mineral sólido y se establecieron las concentraciones óptimas para el desarrollo de células viables: 0.31, 0.19 y 0.13 M para tolueno, benceno y fenol. Los ambientes con concentraciones limitadas de Fe(III) favorecen la producción de piocianina, pigmento que puede interferir en el método analítico de biodegradación de compuestos aromáticos. Este efecto fue eliminado aumentando la concentración de iones de fierro en el medio. Con base en lo anterior, se optimizó y estableció el medio de cultivo mineral con 0.04 g L-1 de FeSO4 en presencia de tolueno (0.03 M) y con esta concentración inicial la tasa de biodegradación fue 75 %. Las pruebas de degradación específicas para los compuestos aromáticos mostraron que la cepa de P. aeruginosa usada puede degradar tolueno, benceno y fenol. Las tasas de degradación fueron mayores para tolueno (58.4 %) y benceno (70.11 %) con concentraciones iniciales de 0.14 M y 0.16 M, y la degradación fue menor para fenol (24.65 %) con una concentración inicial 0.10 M. La capacidad degradadora de P. aeruginosa tuvo proporción directa con su crecimiento en presencia de los xenobióticos estudiados, mostrando una mayor cantidad de proteína celular en los cultivos con benceno (1.4982 mg mL-1), tolueno (0.8629 mg mL-1) y menor en los cultivos desarrollados en presencia de fenol (0.4431 mg mL-1); lo cual muestra que un deficiente desarrollo bacteriano (biomasa) influye en una subóptima biodegradación. Abstract in english A wide range of xenobiotic substances represent a serious problem as environmental pollutants because of their toxicity, among them are found aromatic compounds that can be biodegraded by microorganisms, which use them as their source of carbon and energy. The genus Pseudomonas is outstanding for its multiple biotechnological applications due to its remarkable metabolic versatility. It is capable of producing useful metabolites, enzymatic transformations, biodegradation a (more) nd bioremediation in soil, as well as in water polluted with oil and pesticides. In this study, cells of P. aeruginosa were used to degrade toluene, benzene and phenol. The strain was cultivated in a solid mineral medium, and the following optimal concentrations were established for the development of viable cells: 0.31, 0.19, and 0.13 M for toluene, benzene and phenol. The environments with limited concentrations of Fe(III) favored the production of pyocyanine, a pigment that can interfere in the analytical method of aromatic compound biodegradation. This effect was eliminated by increasing the concentration of iron ions in the medium. On this basis, the mineral culture medium was optimized and established at 0.04 g L-1 FeSO4 in presence of toluene (0.03 M). With this initial concentration, a rate of biodegradation of 75 % was obtained. The specific degradation tests for the aromatic compounds showed that the P. aeruginosa strain used can degrade toluene, benzene and phenol. The rates of degradation were higher for toluene (58.4 °/o) and benzene (70.11 °/o) with the initial concentrations of 0.14 M and 0.16 M. Degradation was less for phenol (24.65 %) with an initial concentration of 0.10 M. The degrading capacity of P. aeruginosa was directly proportional to its growth in the presence of the xenobiotic substances studied. A larger amount of cell protein was exhibited in cultur

Rangel-García, María de L.; Rodríguez-Martínez, Jesús; Garza-García, Yolanda; Martínez-Hernández, José L.

2010-03-01

148

Exposure Evaluation for Benzene, Lead and Noise in Vehicle and Equipment Repair Shops  

Energy Technology Data Exchange (ETDEWEB)

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. Noise dosimetry sampling was performed on a random basis and was representative of the different work activities within the four shops. Twenty three percent of the noise samples exceeded the occupational exposure limit of 85 decibels for an 8-hour time-weightedaverage. Work activities where noise levels were higher included use of impact wrenches and grinding wheels.

Sweeney, Lynn C.

2013-04-10

149

Radiolysis of Aqueous Toluene Solutions  

International Nuclear Information System (INIS)

Aqueous toluene solutions have been irradiated with Co ?-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-, N2O- 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 N2O-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(H2). 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

1971-01-01

150

A novel toluene-3-monooxygenase pathway cloned from Pseudomonas pickettii PKO1.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Plasmid pRO1957, which contains a 26.5-kb fragment from the chromosome of Pseudomonas pickettii PKO1, allows P. aeruginosa PAO1 to grow on toluene or benzene as a sole carbon and energy source. A subclone of pRO1957, designated pRO1966, when present in P. aeruginosa PAO1 grown in lactate-toluene med...

Olsen, R H; Kukor, J J; Kaphammer, B

151

Characterization and Role of tbuX in Utilization of Toluene by Ralstonia pickettii PKO1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The tbu regulon of Ralstonia pickettii PKO1 encodes enzymes involved in the catabolism of toluene, benzene, and related alkylaromatic hydrocarbons. The first operon in this regulon contains genes that encode the tbu pathway's initial catabolic enzyme, toluene-3-monooxygenase, as well as TbuT, the Nt...

Kahng, Hyung-Yeel; Byrne, Armando M.; Olsen, Ronald H.; Kukor, Jerome J.

152

Heterogeneous catalysis by solid superacids--14. Perfluorinated resinsulfonic acid (nafion-h) catalyzed Friedel-crafts alkylation of toluene and phenol with alkyl chloroformates and oxalates  

Energy Technology Data Exchange (ETDEWEB)

Product distributions obtained in the alkylation of toluene with methyl, ethyl, and isopropyl chloroformate and dimethyl oxalate and of phenol with methyl and ethyl chloroformate and dimethyl- and diethyloxalate.

Olah, G.A.; Meidar, D.; Malhotra, R.; Olah, J.A.; Narang, S.C.

1980-01-01

153

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...

154

Electrocardiographic effects of toluene in the anesthetized rat.  

Science.gov (United States)

The influence of inhalation of near lethal quantities of toluene on some ECG parameters, as well as the possible cardiac sensitizing effect of the solvent, were determined in chloralose-anesthetized rats. These actions were compared with those of its close analogue benzene. Both solvents produced tachycardia; toluene increased the duration of QRS and specially PR, while benzene decreased P wave duration. No other systematic changes in ECG morphology or evidence of arrhythmia were observed. Toluene appeared to decrease the number of ectopic beats induced by epinephrine, in contrast to benzene, which increased it markedly. These results suggest that toluene administered by inhalation up to near lethal doses is devoid of untoward ECG effect in the chloralose-anesthetized rat, its only action being a decrease in intraventricular and particularly AV conduction. It does not share the myocardial sensitizing properties of benzene and in fact appears to elicit some protection from the arrhythmogenic effects of epinephrine, although no definite conclusions as to this action can be derived due to limitations in the experimental model used. PMID:3963933

Vidrio, H; Magos, G A; Lorenzana-Jimenez, M

1986-01-01

155

Applicability of urinary benzene to biological monitoring of occupational and environmental exposure to very low benzene concentrations.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To verify whether urinary benzene is an applicable biomarker of occupational exposure to very low concentrations of benzene, considering the influence of cigarette smoke and benzene-toluene co-exposure. MATERIALS AND METHODS: 23 filling station attendants with occupational exposure to benzene and 31 controls were analyzed. Occupational and environmental exposure was monitored and t,t-muconic acid (t,t-MA), S-phenylmercapturic acid (SPMA), urinary benzene and creatinine in the urine samples were tested. RESULTS: Occupational exposure to benzene and toluene was significantly higher in the filling station attendants than in the controls, whereas t,t-MA, SPMA and urinary benzene were not different in the two groups. Instead, the smoker group showed significantly higher values for the above biomarkers than the non-smoker group, each of which included both exposed workers and controls. SPMA was dependent on airborne benzene and cigarette smoking, and urinary benzene only on cigarette smoking, while t,t-MA was not dependent on either of these variables. CONCLUSIONS: At very low concentrations of occupational exposure to benzene, urinary benzene is less valid than SPMA as a biomarker, even if both are strongly influenced by smoking habit. Abstention from smoking should therefore be recommended for at least two hours before urine collection.

Lovreglio P; Carrieri M; Barbieri A; Sabatini L; Fracasso ME; Doria D; Iavicoli S; Drago I; D'errico MN; Imbriani M; Violante FS; Bartolucci GB; Soleo L

2011-01-01

156

Cinnarizinium bis-(p-toluene-sulfonate) dihydrate.  

UK PubMed Central (United Kingdom)

THE ASYMMETRIC UNIT OF THE TITLE SALT [SYSTEMATIC NAME: 1-benzhydryl-4-cinnamylpiperazine-1,4-diium bis-(p-toluene-sulfonate) dihydrate], C26H30N2 (2+)·2C7H7O3S(-)·2H2O, consists of a diprotonated cinnarizinium cation hydrogen bonded through two water mol-ecules to two independent p-toluene-sulfonate anions, one which is disordered over two sets of sites in a 0.793?(3):0.207?(3) ratio. In the cation, the piperazine ring adopts a chair configuration and contains two positively charged N atoms with quarternery character. The dihedral angle between the two benzene rings in the benzhydr-yl group is 71.8?(1)°. The benzene ring flanked opposite the piperazine ring is twisted by 75.9?(9) and 8.8?(3)° from these two benzene rings. In the crystal, the [N-H?Owater-H?O( S)]2 hydrogen-bonded asymmetric unit is connected by further O-H?O hydrogen bonds linking the components into chains along [100].

Kavitha CN; Butcher RJ; Jasinski JP; Yathirajan HS; Dayananda AS

2013-04-01

157

A comparison of the traffic-related benzene, toluene, xylene, and platinum exposure of children living in eastern and western German states; Vergleich der Belastung von Kindern aus den alten und neuen Bundeslaendern mit den verkehrsbedingten Schadstoffen Benzol, Toluol, Xylol und Platin  

Energy Technology Data Exchange (ETDEWEB)

A field study was performed to assess the internal exposure of 149 five- to seven-year old children to traffic-related pollutants. The study was carried out in areas with high and low traffic density located in Western Germany (Essen/Ruhr, Borken, Northrhine-Westphalia) and Eastern Germany (Halle/Saale, Osterburg, Saxony-Anhalt). The benzene, toluene, o-, m-, p-xylene (BTX) concentrations in blood and the platinum excretion in urine served as markers for a traffic-related exposure. The parents were asked to answer a questionaire, which asked for such information as traffic density in the vicinity of the dwelling, redecoration activities inside the rooms, exposure to solvent containing household products, passive smoking, etc. The results of this study show, that emissions from traffic have a significant influence on the internal BTX burden of children. The internal benzene exposure is mainly a result of the benzene concentration in outdoor air, which as a result of the absence of indoor sources is reflected in indoor air. Regarding toluene and xylene indoor air concentrations were generally higher than those outdoors indicating that several relevant indoor sources exist. The urinary platinum (Pt)-excretion of the children from both high traffic areas (Essen/Ruhr, Halle/Saale) tended to higher values when compared with the Pt excretion of those children from the low-traffic areas. However, this differences were statistically not significant. The results of this study do not definitively prove whether emissions from automobile catalysts are responsible for the slightly higher Pt exposure of these children. Keywords: BTX; children; human biological monitoring; platinum; traffic-related exposure (orig.) [German] Im Rahmen des Human-Biomonitorings wurde die verkehrsbedingte interne Fremdstoffbelastung von 149 fuenf- bis siebenjaehrigen Kindern aus je einem hoch und einem niedrig mit Strassenverkehr belastetem Areal aus den alten Bundeslaendern (Essen/Ruhr, Borken, beide Nordrhein-Westfalen) sowie aus den neuen Bundeslaendern (Halle/Saale, Osterburg, beide Sachsen-Anhalt) untersucht. Als Market fuer eine verkehrsbedingte Exposition dienten benzol, Toluol und o-, m-, p-Xylol (BTX) im Blut und Platin im Morgenurin der Kinder. Mittels Fragebogen wurden Angaben zum Ausmass der Verkehrsexposition und zu moeglichen Stoereinfluessen (Zahnersatz, Passivrauchen, Exposition gegenueber loesungsmittelhaltigen Haushaltsprodukten etc.) erfragt. Die Ergebnisse dieser Studie zeigen, dass Emissionen des Kfz-Verkehrs einen nachweisbaren Einfluss auf die interne BTX-Belastung von Kindern haben. Waehrend sich die interne Benzol-belastung im Wesentlichen durch die Aussenluftbelastung mit Benzol durch die Kfz-Verkehrsdichte charakterisieren laesst, die sich mangels interner Quellen in der Innenraumluft widerspiegelt, existieren fuer das Toluol und die Xylole weitere relevante Quellen in Innenraeumen, was sich dadurch zeigt, dass die Toluol- und Xylolkonzentration in der Innenraumluft die in der Aussenluft uebersteigt. Die Platinkonzentrationen im Urin der Kinder aus den beiden verkehrsbelasteten Arealen zeigten im Vergleich zu den Kindern aus den weniger verkehrsbelasteten Arealen eine Tendenz zu hoeheren Werten, die jedoch statistisch nicht signifikant war. Die Ergebnisse lassen deshalb keinen eindeutigen Schluss darueber zu, ob die Ursache in der Freisetzung von Platin aus Autoabgaskatalysatoren liegt. Schlagwoerter: BTX; Human-Biomonitoring; Kinder; Platin; Verkehrsbelastung (orig.)

Begerow, J.; Dunemann, L. [Hygiene-Inst. des Ruhrgebiets, Inst. fuer Umwelthygiene und Umweltmedizin, Gelsenkirchen (Germany); Jermann, E.; Turfeld, M. [Medizinisches Inst. fuer Umwelthygiene, Duesseldorf (Germany); Sugiri, D.; Kraemer, U. [Inst. fuer Umweltmedizinische Forschung gGmbH, Duesseldorf (Germany); Schumann, G. [Hygieneinstitut Sachsen-Anhalt, Magdeburg (Germany)

2003-07-01

158

Polyfunctional catalyst for processiing benzene fractions  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-05-15

159

Investigation of the near-degeneracy effects of the mono-alkyl substituted benzenes by ESR and ENDOR  

International Nuclear Information System (INIS)

Author.In the first chapter, we introduce the theory of ESR and ENDOR spectroscopy. In the second chapter, a description is given of the ESR and ENDOR spectrometers used in our measurements, also included is the sample preparation technique. Chapter three gives an outline of the Huckel and Mclachlan molecular orbital theory used in this thesis. We also discuss the mechanism of proton hyperfine coupling. The effect of alkyl substitution in the lifting of the degeneracy of benzene and the possible explanation of the resulting spin densities, such as the thermal mixing, Jahn-Teller and vibronic effects. In chapter four, we present the results of our ESR and ENDOR measurements on a number of mono-alkyl substituted benzenes. Proton hyperfine splitting constants of toluene, ethyl, n-propyl, n-butyl, n-amyl, iso-propyl, sec-butyl, t-butyl benzenes, 1-phenyl hexane and 1-phenyl heptane are reported. The results are discussed in the light of spin density calculations using the HMO and Mclachlan methods and compared with other calculations found in the literature. Estimations of the mining between the two lowest antibonding states have been made. Finally, temperature dependence of some of the splittings were measured in an attempt to determine the importance of the thermal contribution of the mixing

1988-01-01

160

[Lesser validity of urinary benzene than S-phenylmercapturic acid for measuring occupational and environmental exposure to very low concentrations of benzene].  

UK PubMed Central (United Kingdom)

AIM: To study the validity of urinary benzene as a biomarker of low and very low exposure to this toxicant, as compared with t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (SPMA), also taking into account the influence of cigarette smoking and co-exposure to toluene on the urinary excretion of benzene. MATERIALS AND METHODS: The results obtained in two different studies were compared: in the first, workers occupationally exposed to low concentrations of benzene (18 fuel tanker drivers and 23 filling station attendants) were compared with 31 controls and in the second, workers exposed to very low concentrations of benzene (the same 23 filling station attendants) were compared with the 31 controls. Exposure to airborne benzene and toluene was monitored with passive personal samplers (Radiello). Then the urine collected at the end of the work shift was analyzed for t,t-MA, SPMA and urinary benzene. All participants also filled out a questionnaire about their lifestyle habits. RESULTS: There were no differences among the three groups in terms of age and smoking habit. Occupational exposure to benzene and toluene and the urinary concentrations of t,t-MA, SPMA and urinary benzene were higher in the fuel tanker drivers than the filling station attendants and higher in the latter than in the controls. Cigarette smoking was found to be associated with urinary excretion of t,t-MA, SPMA and urinary benzene at both low and very low exposure to benzene. The biomarkers t,t-MA, SPMA and urinary benzene were almost always correlated, for both low and very low exposure to benzene. Notably, for low exposure to benzene a dependency relation was found with the levels of t,t-MA, SPMA and urinary benzene on both cigarette smoking and airborne benzene, whereas for very low exposure to benzene there was a dependency relation of SPMA on cigarette smoking and airborne benzene, of urinary benzene only on cigarette smoking and of t,t-MA on none of the variables considered. CONCLUSIONS: For occupational exposure to low concentrations of benzene, urinary benzene and SPMA showed a comparable validity, while for exposure to very low concentrations of this toxicant the validity of SPMA was confirmed while urinary benzene was found to be less useful. Cigarette smoking was the main factor conditioning the excretion of all the biomarkers of benzene in conditions of both low and very low exposure to the toxicant, so for the analysis of occupational exposure to benzene it is best to recommend abstention from smoking at least in the hours immediately before urine collection.

Lovreglio P; Barbieri A; Carrieri M; Sabatini L; Fracasso ME; Doria D; Drago I; Basso A; D'Errico MN; Bartolucci GB; Violante FS; Soleo L

2011-04-01

 
 
 
 
161

Poly(N,N'-dichloro-N-ethyl-benzene-1, 3-disulfonamide) and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide as novel catalytic reagents for synthesis of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl)methanes under solid-state, solvent and water conditions  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Descreve-se a preparação fácil e rápida de bis-indolil, tris-indolil, di(bis-indolil), tri(bis-indolil) e tetra(bis-indolil) metanos a partir de indole com diferentes aldeídos e cetonas, sob diferentes condições reacionais, usando poly(N,N´-dicloro-N-etil-benzeno-1,3 -disulfonamida), [PCBS], e N,N,N´,N´-tetraclorobenzeno-1,3-disulfonamida, [TCBDA], como novos catalizadores. Abstract in english Easy and rapid preparation of bis-indolyl, tris-indolyl, di(bis-indolyl), tri(bis-indolyl) and tetra(bis-indolyl) methanes from indole with various aldehydes and ketones using poly (N,N'-dichloro-N-ethyl-benzene-1,3-disulfonamide) [PCBS] and N,N,N',N'-tetrachlorobenzene-1,3-disulfonamide [TCBDA] as novel catalysts under various conditions are here described.

Ghorbani-Vaghei, Ramin; Veisi, Hojat

2010-01-01

162

Luminescence of toluene and deuterium-substituted toluenes at 770 K in polycrystalline methylcyclohexane  

International Nuclear Information System (INIS)

The luminescence spectra of C6H5CH3, o-, m- and p-DC6H4CH3, C6H5CD3, C6D5CH3 and C6D5CD3 in polycrystalline methylcyclohexane at 770 K have been studied. The vibrational analyses of the phosphorescences and fluorescences of these isotopically related molecules are reported. For the phosphorescences, progressions in a totally symmetric ring carbon-carbon stretching frequency, based mainly on one quantum of a non-totally symmetric vibration of esub(2g) parentage in benzene, are interpreted to signify a planar, non-regular hexagon ring structure for the lowest triplet state of the toluenes. In the fluorescences, progressions in the ring breathing mode, with a different esub(2g) mode of benzene serving as a false origin, are suggestive of an expanded regular hexagon ring geometry of the lowest excited singlet state. (author).

1976-01-01

163

CFD SIMULATIONS OF BENZENE –TOLUENE SYSTEM OVER SIEVE TRAY  

Directory of Open Access Journals (Sweden)

Full Text Available High degree of competitiveness associated with petroleum leads to the exhaustive search for new technologies that enable greater efficiency in the related processes. A three-dimensional mathematical homogeneous biphasic model was implemented in the commercial code of computational fluid dynamics (CFD), FLUENT package to predict concentration and temperature distributions on sieve trays of distillation columns and good simulation results are obtained. The tray geometries and operating conditions are based on the experimental works of Indian oil corporation limited(R & D). The dispersed gas phase and continuous liquid phase are modelled in the Mixture model for two interpenetrating phases with inter phase momentum, heat and mass transfer. The main objective of this study has been to find the extent to which CFD can be used as a prediction tool for real behaviour, and concentration and temperature distributions of sieve trays. The simulation results are shown that CFD is a powerful tool in tray design, analysis and trouble shooting, and can be considered as a new approach for efficiency calculations.

Sumit Singh

2012-01-01

164

Health aspects of toluene and xylene exposures associated with motor gasoline  

Energy Technology Data Exchange (ETDEWEB)

In response to concerns that exposures to toluene and xylenes during the manufacture, distribution, and use of motor gasolines may present similar risks to the potential blood and bone marrow abnormalities from over-exposure to benzene, the report reviews current scientific knowledge on human and animal health effects. Data are also presented on the ranges of concentrations of toluene and xylenes in European gasolines and on exposures to their vapors during the manufacture and distribution of motor gasolines.

Eyres, A.R.

1987-01-01

165

4-(3-Carboxy-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinolin-7-yl)piperazin-1-ium 4-carboxybenzoate–benzene-1,4-dicarboxylic acid (2/1)  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C16H19FN3O3+·C8H5O4?·0.5C8H6O4, the benzene-1,4-dicarboxylic acid molecule is located on a centre of symmetry. In the crystal, the molecules and ions are connected by intermolecular C—H...O and O—H...O hydrogen bonds and ?–? stacking interactions [with a centroid–centroid distance of 3.402?(2)?Å], generating a three-dimensional supramolecular structure.

Shi-Wei Yan; Hai-Yan Chen; Guang-Ju Zhang; Qin Liao; Yan-Chen Liang

2011-01-01

166

Isolation and characterization of benzene-tolerant Rhodococcus opacus strains.  

Science.gov (United States)

Twenty-two benzene-utilizing bacteria were isolated from soil samples. Among them, three isolates were highly tolerant to benzene. They grew on benzene when liquid benzene was added to the basal salt medium at 10--90% (v/v). Taxonomical analysis identified the benzene-tolerant isolates as Rhodococcus opacus. One of the benzene-tolerant isolates, designated B-4, could utilize many aromatic and aliphatic hydrocarbons including benzene, toluene, styrene, xylene, ethylbenzene, propylbenzene, n-octane and n-decane as sole sources of carbon and energy. Strain B-4 grew well in the presence of 10% (v/v) organic solvents that it was capable of using as growth substrates. Genetic analysis revealed the benzene dioxygenase pathway is involved in benzene catabolism in strain B-4. A deletion-insertion mutant defective in the benzene dioxygenase large and small subunits genes (bnz A 1 and bnz A 2) was as tolerant to organic solvents as the wild-type strain B-4, suggesting that utilization or degradation of organic solvents is not essential for the organic solvent tolerance of R. opacus B-4. PMID:16233805

Na, Kyung-Su; Kuroda, Akio; Takiguchi, Noboru; Ikeda, Tsukasa; Ohtake, Hisao; Kato, Junichi

2005-04-01

167

Isolation and characterization of benzene-tolerant Rhodococcus opacus strains.  

UK PubMed Central (United Kingdom)

Twenty-two benzene-utilizing bacteria were isolated from soil samples. Among them, three isolates were highly tolerant to benzene. They grew on benzene when liquid benzene was added to the basal salt medium at 10--90% (v/v). Taxonomical analysis identified the benzene-tolerant isolates as Rhodococcus opacus. One of the benzene-tolerant isolates, designated B-4, could utilize many aromatic and aliphatic hydrocarbons including benzene, toluene, styrene, xylene, ethylbenzene, propylbenzene, n-octane and n-decane as sole sources of carbon and energy. Strain B-4 grew well in the presence of 10% (v/v) organic solvents that it was capable of using as growth substrates. Genetic analysis revealed the benzene dioxygenase pathway is involved in benzene catabolism in strain B-4. A deletion-insertion mutant defective in the benzene dioxygenase large and small subunits genes (bnz A 1 and bnz A 2) was as tolerant to organic solvents as the wild-type strain B-4, suggesting that utilization or degradation of organic solvents is not essential for the organic solvent tolerance of R. opacus B-4.

Na KS; Kuroda A; Takiguchi N; Ikeda T; Ohtake H; Kato J

2005-04-01

168

Materials balance for benzene: Level II. Final report  

Energy Technology Data Exchange (ETDEWEB)

A Level II materials balance was performed on benzene. Data are reported for benzene production from petroleum by four processes (catalytic reformation, toluene dealkylation, toluene disproportionation, and isolation from pyrolysis gasoline) for production from coal during coking. Amounts of benzene consumed for the synthesis of eight direct derivatives (ethylbenzene, cumene, cyclohexane, nitrobenzene, maleic anhydride, mono- and dichlorobenzene, alkylbenzenes, and biphenyl) and exports are presented. These uses constitute approximately 99 percent of total benzene usage. Nonconsumptive uses (solvents and pesticide component) are also tabulated. Releases due to each of the above processes are reported or estimated where possible using published and unpublished data. In addition, releases due to indirect production (refinery operation, coke oven operations, oil spills, non-ferrous metals manufacturing, ore mining, wood processing, coal mining, and two phases of the textile industry) are presented. Production of benzene as a component of gasoline and releases due to all phases of gasoline use are estimated. Locations of sites with high levels of benzene releases due to production and use are tabulated: the major 'hotspots' are Baton Rouge, Louisiana; Houston/Galveston, Texas; Midland, Michigan; and Puerto Rico. The uncertainty ranges of all numbers used or derived in this report are evaluated when possible and tabulated. Data gaps are evaluated and general recommendations are presented. The results of the report are summarized in two figures: the Environmental Flow Diagram for benzene in Appendix A, and the Materials Balance Flow Diagram in the Executive Summary.

Hall, R.L.; Burger, R.; Montecalvo, F.

1980-05-01

169

Pallidol hexaacetate ethyl acetate monosolvate  

Directory of Open Access Journals (Sweden)

Full Text Available The entire molecule of pallidol hexaacetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis[4-(acetyloxy)phenyl]-4b,5,9b,10-tetrahydroindeno[2,1-a]indene-1,3,6,8-tetrayl tetraacetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate molecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexaacetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?Å) is 54.73?(6)°, indicating a significant fold in the molecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carboxy)—C—C torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)°]. In the crystal, a three-dimensional architecture is sustained by C—H...O interactions which encompass channels in which the disordered ethyl acetate molecules reside.

Qinyong Mao; Dennis K. Taylor; Seik Weng Ng; Edward R. T. Tiekink

2013-01-01

170

Mapping the binding pocket of dual antagonist almorexant to human orexin 1 and orexin 2 receptors: comparison with the selective OX1 antagonist SB-674042 and the selective OX2 antagonist N-ethyl-2-[(6-methoxy-pyridin-3-yl)-(toluene-2-sulfonyl)-amino]-N-pyridin-3-ylmethyl-acetamide (EMPA).  

Science.gov (United States)

The orexins and their receptors are involved in the regulation of arousal and sleep-wake cycle. Clinical investigation with almorexant has indicated that this dual OX antagonist is efficacious in inducing and maintaining sleep. Using site-directed mutagenesis, beta(2)-adrenergic-based OX(1) and OX(2) modeling, we have determined important molecular determinants of the ligand-binding pocket of OX(1) and OX(2). The conserved residues Asp(45.51), Trp(45.54), Tyr(5.38), Phe(5.42), Tyr(5.47), Tyr(6.48), and His(7.39) were found to be contributing to both orexin-A-binding sites at OX(1) and OX(2). Among these critical residues, five (positions 45.51, 45.54, 5.38, 5.42, and 7.39) were located on the C-terminal strand of the second extracellular loop (ECL2b) and in the top of TM domains at the interface to the main binding crevice, thereby suggesting superficial OX receptor interactions of orexin-A. We found that the mutations W214A(45.54), Y223A(5.38), F227A(5.42), Y317A(6.48), and H350A(7.39) resulted in the complete loss of both [(3)H]almorexant and [(3)H]N-ethyl-2-[(6-methoxy-pyridin-3-yl)-(toluene-2-sulfonyl)-amino]-N-pyridin-3-ylmethyl-acetamide (EMPA) binding affinities and also blocked their inhibition of orexin-A-evoked [Ca(2+)](i) response at OX(2). The crucial residues Gln126(3.32), Ala127(3.33), Trp206(45.54), Tyr215(5.38), Phe219(5.42), and His344(7.39) are shared between almorexant and 1-(5-(2-fluoro-phenyl)-2-methyl-thiazol-4-yl)-1-((S)-2-(5-phenyl-(1,3,4)oxadiazol-2-ylmethyl)-pyrrolidin-1-yl)-methanone (SB-674042) binding sites in OX(1). The nonconserved residue at position 3.33 of orexin receptors was identified as occupying a critical position that must be involved in subtype selectivity and also in differentiating two different antagonists for the same receptor. In summary, despite high similarities in the ligand-binding pockets of OX(1) and OX(2) and numerous aromatic/hydrophobic interactions, the local conformation of helix positions 3.32, 3.33, and 3.36 in transmembrane domain 3 and 45.51 in ECL2b provide the structural basis for pharmacologic selectivity between OX(1) and OX(2). PMID:20404073

Malherbe, Pari; Roche, Olivier; Marcuz, Anne; Kratzeisen, Claudia; Wettstein, Joseph G; Bissantz, Caterina

2010-04-19

171

Mapping the binding pocket of dual antagonist almorexant to human orexin 1 and orexin 2 receptors: comparison with the selective OX1 antagonist SB-674042 and the selective OX2 antagonist N-ethyl-2-[(6-methoxy-pyridin-3-yl)-(toluene-2-sulfonyl)-amino]-N-pyridin-3-ylmethyl-acetamide (EMPA).  

UK PubMed Central (United Kingdom)

The orexins and their receptors are involved in the regulation of arousal and sleep-wake cycle. Clinical investigation with almorexant has indicated that this dual OX antagonist is efficacious in inducing and maintaining sleep. Using site-directed mutagenesis, beta(2)-adrenergic-based OX(1) and OX(2) modeling, we have determined important molecular determinants of the ligand-binding pocket of OX(1) and OX(2). The conserved residues Asp(45.51), Trp(45.54), Tyr(5.38), Phe(5.42), Tyr(5.47), Tyr(6.48), and His(7.39) were found to be contributing to both orexin-A-binding sites at OX(1) and OX(2). Among these critical residues, five (positions 45.51, 45.54, 5.38, 5.42, and 7.39) were located on the C-terminal strand of the second extracellular loop (ECL2b) and in the top of TM domains at the interface to the main binding crevice, thereby suggesting superficial OX receptor interactions of orexin-A. We found that the mutations W214A(45.54), Y223A(5.38), F227A(5.42), Y317A(6.48), and H350A(7.39) resulted in the complete loss of both [(3)H]almorexant and [(3)H]N-ethyl-2-[(6-methoxy-pyridin-3-yl)-(toluene-2-sulfonyl)-amino]-N-pyridin-3-ylmethyl-acetamide (EMPA) binding affinities and also blocked their inhibition of orexin-A-evoked [Ca(2+)](i) response at OX(2). The crucial residues Gln126(3.32), Ala127(3.33), Trp206(45.54), Tyr215(5.38), Phe219(5.42), and His344(7.39) are shared between almorexant and 1-(5-(2-fluoro-phenyl)-2-methyl-thiazol-4-yl)-1-((S)-2-(5-phenyl-(1,3,4)oxadiazol-2-ylmethyl)-pyrrolidin-1-yl)-methanone (SB-674042) binding sites in OX(1). The nonconserved residue at position 3.33 of orexin receptors was identified as occupying a critical position that must be involved in subtype selectivity and also in differentiating two different antagonists for the same receptor. In summary, despite high similarities in the ligand-binding pockets of OX(1) and OX(2) and numerous aromatic/hydrophobic interactions, the local conformation of helix positions 3.32, 3.33, and 3.36 in transmembrane domain 3 and 45.51 in ECL2b provide the structural basis for pharmacologic selectivity between OX(1) and OX(2).

Malherbe P; Roche O; Marcuz A; Kratzeisen C; Wettstein JG; Bissantz C

2010-07-01

172

21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.  

Science.gov (United States)

... false Ethyl alcohol containing ethyl acetate. 584.200 Section 584.200 Food...200 Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR...

2010-04-01

173

2-[(1Z)-(9-Ethyl-9H-carbazol-3-yl)methyleneamino]-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile–benzene (2/1)  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, 2C24H21N3S·C6H6, the two independent Schiff base molecules (A and B) in the asymmetric unit differ in the orientation of the tetrahydrobenzothiophene ring system with respect to the carbazole ring system by 180° rotation about the C—C bond in the C—C=N—C linkage. The two molecules also differ in the orientation of the ethyl groups [C—N—C—C torsion angle of 90.7?(3)° in molecule A, and ?79.4?(3)° in molecule B]. In molecule B, two methylene C atoms of the cyclohexene ring are disordered over two sites with occupancies of 0.58?(1) and 0.42?(1). The cyclohexene rings in both molecules adopt half-chair conformations. The dihedral angle between the thiophene ring and the carbazole ring system is 8.07?(9)° in molecule A [3.10?(9)° in molecule B]. In the crystal structure, the independent molecules are linked into dimers by intermolecular C—H...N hydrogen bonds. In addition, C—H...? interactions are observed.

Hoong-Kun Fun; Jia Hao Goh; Abdullah M. Asiri; Salman A. Khan; Khalid A. Khan

2010-01-01

174

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2007-09-15

175

Method for producing benzene aromatic hydrocarbon from crude benzole  

UK PubMed Central (United Kingdom)

The present invention relates to process of producing benzene series arene with crude benzole. Whole fraction crude benzole and other hydrocarbon oil are mixed, and the mixed oil is produced into high purity benzene, toluene and xylene through the process including hydrorefining, reforming, solvent extracting, distilling, rectifying and other steps. The present invention has the features of no arene loss, total arene yield over 100 %, high purity of arene products over 99.9 %, low S and N impurity content in arene products less than 1 ppm and long operation period of the processing apparatus. The present invention is especially suitable for use in refinery possessing hydrogenation equipment and reforming equipment.

SHE XICHUN ZHU

176

Decreased benzene evaporative emission from an oxygenated fuel  

Energy Technology Data Exchange (ETDEWEB)

A chromatographic head-space analysis was developed to determine the vapor phase concentrations of non-oxygenated and oxygenated fuels. The effect of ether oxygenates on benzene evaporative emissions was evaluated. A base fuel and three oxygenated fuels were prepared to contain 1 volume percent benzene at matched volatility levels. Head-space composition for each blend was measured, as a function of temperature, to determine the effects of oxygenates on benzene volatility. Results indicate MTBE (methyl tert-butyl ether), ETBE (ethyl tert-butyl ether), and TAME (tert-amyl methyl ether) each reduce benzene vapor phase concentrations. Benzene reductions averaged approximately 14 percent for fuels containing 2.7 weight percent oxygen. Reductions were temperature dependent, but not generally dependent upon type of ether oxygenate. Significant environmental benefits result from reducing benzene volatility and the resulting decrease in evaporative emissions. Benzene is classified by the EPA as a known human carcinogen. The 1990 Clean Air Act Amendments require reductions in gasoline benzene levels to reduce toxic emissions.

Bobro, C.H.; Karas, L.J.; Leaseburge, C.D.; Skahan, D.J. [ARCO Chemical CO., Newton Square, PA (United States)

1994-12-31

177

Metabolic acidosis in toluene sniffing.  

UK PubMed Central (United Kingdom)

ABSTRACTToluene sniffing, frequently described under the generic category of "glue sniffing," is a potential cause of normal anion gap metabolic acidosis due to distal renal tubular acidosis. Urine anion gap is used to diagnose metabolic acidosis of a normal anion gap variety; however, pitfalls exist when using urine anion gap in the setting of toluene sniffing. We present the case of a young woman who had a normal anion gap metabolic acidosis due to toluene sniffing and an unexpectedly low urine anion gap. In such a scenario, the urine anion gap will underestimate the rate of ammonia excretion when the conjugate bases of acids other than HCl are excreted in large quantities. Estimation of the urine osmolal gap will provide a more accurate ammonia excretion rate in these circumstances. The challenges in interpretation of the urine anion gap and ammonia excretion in the setting of distal renal tubular acidosis due to toluene toxicity are discussed.

Tuchscherer J; Rehman H

2013-07-01

178

Metabolic acidosis in toluene sniffing.  

Science.gov (United States)

ABSTRACTToluene sniffing, frequently described under the generic category of "glue sniffing," is a potential cause of normal anion gap metabolic acidosis due to distal renal tubular acidosis. Urine anion gap is used to diagnose metabolic acidosis of a normal anion gap variety; however, pitfalls exist when using urine anion gap in the setting of toluene sniffing. We present the case of a young woman who had a normal anion gap metabolic acidosis due to toluene sniffing and an unexpectedly low urine anion gap. In such a scenario, the urine anion gap will underestimate the rate of ammonia excretion when the conjugate bases of acids other than HCl are excreted in large quantities. Estimation of the urine osmolal gap will provide a more accurate ammonia excretion rate in these circumstances. The challenges in interpretation of the urine anion gap and ammonia excretion in the setting of distal renal tubular acidosis due to toluene toxicity are discussed. PMID:23778000

Tuchscherer, Jon; Rehman, Habib

2013-07-01

179

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

UK PubMed Central (United Kingdom)

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.

Ahmed A; Ghosh MK; Choi MC; Choi CH; Kim S

2013-03-01

180

Which Hydrogen Atom of Toluene Protonates PAH molecules in (+)-Mode APPI MS Analysis?  

Science.gov (United States)

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.

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

2013-03-01

 
 
 
 
181

DETERMINATION OF BENZENE IN AIR BY MICROCOLUMN ADSORPTION AND THERMAL DESORPTION IN GC INLET  

Directory of Open Access Journals (Sweden)

Full Text Available The air sample is passed through the glass microcolumn filled with Tenax, which is then transferred into a modified GC injection port for thermal desorption and without cryofocusation analyzed. A linear working range for benzene, toluene, ethylbenzene and p-xylene at the amounts of 4-20 ng per microcolumn was established with correlation coeficients (r2) within the range, 0.99896 – 0.99952. Limit of detection for benzene (analyzing 200 ml of air sample) lies under 3µg/m3. The method has been successfully applied for the determination of benzene in crossroad air.

Eva Krá?ovi?ová; Ján Hriv?ák; Peter Tölgyessy

2006-01-01

182

N-acetyl-beta-D-glucosaminidase in lymphocytes of workers exposed to benzene and its homologues  

Energy Technology Data Exchange (ETDEWEB)

In 108 workers having occupational contact with benzene and its homologues by 1 to 122 months, the activity of N-acetyl-beta-D-glucosaminidase (NAG) within the peripheral blood lymphocytes was estimated by means of cytochemical method. The benzene, the toluene and the xylene concentration at work stands was equal to 0-370, 0-580 and 0-560 mg/cu . m, respectively. In 41 workers having the service time equal to 55-122 months the NAG deficiency within the lymphocyte lysosomes was stated. Above phenomenon is probably due to disintegration of lysosomes caused by lipophilic properties of benzene.

Moszczynski, P.; Lisiewicz, J.

1984-01-01

183

Toluene 2-Monooxygenase-Dependent Growth of Burkholderia cepacia G4/PR1 on Diethyl Ether.  

Science.gov (United States)

Aerobic bacterial growth on aromatic hydrocarbons typically requires oxygenase enzymes, which are known to fortuitously oxidize nongrowth substrates. In this study, we found that oxidation of diethyl ether by toluene 2-monooxygenase supported more rapid growth of Burkholderia cepacia G4/PR1 than did the aromatic substrates n-propylbenzene and o-xylene. The wild-type Burkholderia cepacia G4 failed to grow on diethyl ether. Purified toluene 2-monooxygenase protein components oxidized diethyl ether stoichiometrically to ethanol and acetaldehyde. Butyl methyl ether, diethyl sulfide, and 2-chloroethyl ethyl ether were oxidized by B. cepacia G4/PR1. PMID:16535583

Hur, H; Newman, L M; Wackett, L P; Sadowsky, M J

1997-04-01

184

Toluene 2-Monooxygenase-Dependent Growth of Burkholderia cepacia G4/PR1 on Diethyl Ether.  

UK PubMed Central (United Kingdom)

Aerobic bacterial growth on aromatic hydrocarbons typically requires oxygenase enzymes, which are known to fortuitously oxidize nongrowth substrates. In this study, we found that oxidation of diethyl ether by toluene 2-monooxygenase supported more rapid growth of Burkholderia cepacia G4/PR1 than did the aromatic substrates n-propylbenzene and o-xylene. The wild-type Burkholderia cepacia G4 failed to grow on diethyl ether. Purified toluene 2-monooxygenase protein components oxidized diethyl ether stoichiometrically to ethanol and acetaldehyde. Butyl methyl ether, diethyl sulfide, and 2-chloroethyl ethyl ether were oxidized by B. cepacia G4/PR1.

Hur H; Newman LM; Wackett LP; Sadowsky MJ

1997-04-01

185

The Impact of Candle Burning During All Saints' Day Ceremonies on Ambient Alkyl-Substituted Benzene Concentrations.  

UK PubMed Central (United Kingdom)

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.

Olszowski T; K?os A

2013-09-01

186

Benzene Monitor System report  

International Nuclear Information System (INIS)

Two systems for monitoring benzene in aqueous streams have been designed and assembled by the Savannah River Technology Center, Analytical Development Section (ADS). These systems were used at TNX to support sampling studies of the full-scale open-quotes SRAT/SME/PRclose quotes and to provide real-time measurements of benzene in Precipitate Hydrolysis Aqueous (PHA) simulant. This report describes the two ADS Benzene Monitor System (BMS) configurations, provides data on system operation, and reviews the results of scoping tests conducted at TNX. These scoping tests will allow comparison with other benzene measurement options being considered for use in the Defense Waste Processing Facility (DWPF) laboratory. A report detailing the preferred BMS configuration statistical performance during recent tests has been issued under separate title: Statistical Analyses of the At-line Benzene Monitor Study, SCS-ASG-92-066. The current BMS design, called the At-line Benzene Monitor (ALBM), allows remote measurement of benzene in PHA solutions. The authors have demonstrated the ability to calibrate and operate this system using peanut vials from a standard Hydragard trademark sampler. The equipment and materials used to construct the ALBM are similar to those already used in other applications by the DWPF lab. The precision of this system (±0.5% Relative Standard Deviation (RSD) at 1 sigma) is better than the purge ampersand trap-gas ctograpy reference method currently in use. Both BMSs provide a direct measurement of the benzene that can be purged from a solution with no sample pretreatment. Each analysis requires about five minutes per sample, and the system operation requires no special skills or training. The analyzer's computer software can be tailored to provide desired outputs. Use of this system produces no waste stream other than the samples themselves (i.e. no organic extractants).

1992-01-01

187

Benzene Monitor System report  

Energy Technology Data Exchange (ETDEWEB)

Two systems for monitoring benzene in aqueous streams have been designed and assembled by the Savannah River Technology Center, Analytical Development Section (ADS). These systems were used at TNX to support sampling studies of the full-scale {open_quotes}SRAT/SME/PR{close_quotes} and to provide real-time measurements of benzene in Precipitate Hydrolysis Aqueous (PHA) simulant. This report describes the two ADS Benzene Monitor System (BMS) configurations, provides data on system operation, and reviews the results of scoping tests conducted at TNX. These scoping tests will allow comparison with other benzene measurement options being considered for use in the Defense Waste Processing Facility (DWPF) laboratory. A report detailing the preferred BMS configuration statistical performance during recent tests has been issued under separate title: Statistical Analyses of the At-line Benzene Monitor Study, SCS-ASG-92-066. The current BMS design, called the At-line Benzene Monitor (ALBM), allows remote measurement of benzene in PHA solutions. The authors have demonstrated the ability to calibrate and operate this system using peanut vials from a standard Hydragard{trademark} sampler. The equipment and materials used to construct the ALBM are similar to those already used in other applications by the DWPF lab. The precision of this system ({+-}0.5% Relative Standard Deviation (RSD) at 1 sigma) is better than the purge & trap-gas chromatograpy reference method currently in use. Both BMSs provide a direct measurement of the benzene that can be purged from a solution with no sample pretreatment. Each analysis requires about five minutes per sample, and the system operation requires no special skills or training. The analyzer`s computer software can be tailored to provide desired outputs. Use of this system produces no waste stream other than the samples themselves (i.e. no organic extractants).

Livingston, R.R.

1992-10-12

188

Benzene in the workplace  

Energy Technology Data Exchange (ETDEWEB)

It has long been recognized that overexposure to benzene could result in damage to the blood-forming organs of the body. More recently, it has become apparent that chronic high levels of exposure are associated with the development of leukemia. Animal experiments have also suggested that overexposure to benzene may result in certain reproductive risks. Toxicological and epidemiological evidence indicate that benzene is capable of causing serious blood effects at high levels. While the effects observed in animals are very weak, more research is underway to define the limits of exposure believed to be safe with respect to reproductive effects in workers of either sex. Levels of benzene in air at 10 ppM or less can be determined with sufficient accuracy to evaluate the integrated or peak exposures of workers during their working hours. Where exposure in excess of accepted levels occurs, substitution with other less toxic materials, coupled with adequate controls and strict work practices for handling benzene or benzene-containing compounds, are capable of minimizing or eliminating health hazards associated with this extremely important and useful chemical.

Brief, R.S.; Lynch, J.; Bernath, T.; Scala, R.A.

1980-09-01

189

Shape-selective reactions with zeolite catalysts. VI. Alkylation of benzene with propylene to produce cumene  

Energy Technology Data Exchange (ETDEWEB)

Zeolite catalysts have been tested for alkylation of benzene with propylene to produce cumene and cymene from toluene by alkylation with propylene. Conditions of reaction were optimized with certain rare-earth-modified zeolites to give 75-80% cumene yields. Previous papers in this series have been concerned primarily with alkylation of benzene or toluene with methanol or ethylene. The latter reagents are very active under alkylating conditions and will oligomerize and react to give a variety of undesired by-products. Five to ten molar excesses of the aromatic component are needed to promote the desired alkylation reaction. Propylene is also very active and requires a similar excess of the aromatic component. In addition, there is potential for production of n- and isopropylbenzene. The results from alkylation of benzene with propylene using HZSM-5 are discussed here. 15 references.

Kaeding, W.W.; Holland, R.E.

1988-01-01

190

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

UK PubMed Central (United Kingdom)

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 <0.001-0.69 ppm), 0.05 ppm for toluene, 0.02 ppm for 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.

Bråtveit M; Kirkeleit J; Hollund BE; Moen BE

2007-07-01

191

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

Science.gov (United States)

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 <0.001-0.69 ppm), 0.05 ppm for toluene, 0.02 ppm for 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. PMID:17607018

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

2007-07-02

192

Metabolites detected during biodegradation of 13C6-benzene in nitrate-reducing and methanogenic enrichment cultures.  

UK PubMed Central (United Kingdom)

The mechanism for anaerobic metabolism of benzene remains unknown. To date, there have been only a few studies reporting metabolites of anaerobic benzene biodegradation, in part because anaerobic benzene-degrading enrichment cultures are not very common and only two isolates have been characterized to date. Phenol and benzoate, metabolites consistent with benzene hydroxylation or benzene carboxylation, have been identified previously in mixed cultures, and more recently benzene methylation to toluene has been proposed as another possible mechanism for anaerobic benzene degradation. In this study, 13C6-benzene was added to nitrate-reducing and methanogenic enrichment cultures and specific 13C-labeled metabolites were monitored over time. The putative metabolites were detected by gas chromatography/mass spectrometry in ether extracts of 100-mL samples of culture taken at each time point. This method of analysis provided the sensitivity required to accurately quantify low concentrations of these compounds. In addition, benzoate trapping was used in an attemptto increase concentrations of upstream metabolites. In both cultures, in the presence and absence of unlabeled benzoate (trap), [ring-13C]-toluene and [ring-13C]benzoate were detected transiently during degradation. The data strongly support initial methylation of benzene to toluene, followed bytransformation to benzoate. Although benzene methylation has been proposed previously, this is the first direct evidence to supportthis pathway. In the methanogenic culture only, 13C6-phenol was also detected. The transient appearance of phenol, which appeared to be further transformed to benzoate, suggests that a pathway involving hydroxylation to phenol, as proposed in other studies, was also operative.

Ulrich AC; Beller HR; Edwards EA

2005-09-01

193

Vibrations of the low energy states of toluene (X?(1)A1 and A?(1)B2) and the toluene cation (X?(2)B1).  

UK PubMed Central (United Kingdom)

We commence by presenting an overview of the assignment of the vibrational frequencies of the toluene molecule in its ground (S0) state. The assignment given is in terms of a recently proposed nomenclature, which allows the ring-localized vibrations to be compared straightforwardly across different monosubstituted benzenes. The frequencies and assignments are based not only on a range of previous work, but also on calculated wavenumbers for both the fully hydrogenated (toluene-h8) and the deuterated-methyl group isotopologue (?3-toluene-d3), obtained from density functional theory (DFT), including artificial-isotope shifts. For the S1 state, one-colour resonance-enhanced multiphoton ionization (REMPI) spectroscopy was employed, with the vibrational assignments also being based on previous work and time-dependent density functional theory (TDDFT) calculated values; but also making use of the activity observed in two-colour zero kinetic energy (ZEKE) spectroscopy. The ZEKE experiments were carried out employing a (1 + 1(')) ionization scheme, using various vibrational levels of the S1 state with an energy <630 cm(-1) as intermediates; as such we only discuss in detail the assignment of the REMPI spectra at wavenumbers <700 cm(-1), referring to the assignment of the ZEKE spectra concurrently. Comparison of the ZEKE spectra for the two toluene isotopologues, as well as with previously reported dispersed-fluorescence spectra, and with the results of DFT calculations, provide insight both into the assignment of the vibrations in the S1 and D0(+) states, as well as the couplings between these vibrations. In particular, insight into the nature of a complicated Fermi resonance feature at ?460 cm(-1) in the S1 state is obtained, and Fermi resonances in the cation are identified. Finally, we compare activity observed in both REMPI and ZEKE spectroscopy for both toluene isotopologues with that for fluorobenzene and chlorobenzene.

Gardner AM; Green AM; Tamé-Reyes VM; Wilton VH; Wright TG

2013-04-01

194

The use of radioisotopes in radiation chemistry: the effect of radiation on toluene  

International Nuclear Information System (INIS)

The radiation chemistry of organic compounds can often be studied more effectively and in greater detail using compounds labelled with radioisotopes. Use of this approach permits observation of products not otherwise detectable and provides information about the processes by which they are formed. The versatility of this technique is illustrated by results obtained in a study of the radiation chemistry of toluene. Toluene labelled in the methyl group with tritium (one atom per 600 mol.), was prepared and was exposed in the vapour phase to gamma-radiation (1.46 eV/mol.). The product was fractionated and the volatile fractions were injected into a gas fractometer equipped with an ionization chamber to permit simultaneous recording of radioactivity and thermal conductivity. Concentrations of tritium in the various products were determined from relative areas under peaks in the two curves. From the concentrations of tritium in these products it can be deduced that the methane is formed exclusively from the methyl group of toluene and that the xylenes are formed by attack of methyl radicals on toluene. Oxidation of the recovered toluene showed that transfer of tritium from the methyl group, to the benzene ring had occurred to some extent during the irradiation. The benzoic acid contained one tritium atom per 140000 molecules, corresponding to a G value of 0.3 for the ''exchange'' reaction. This appearance of tritium in the ring could result either from abstraction of methyl hydrogen by a tolyl radical or from reconversion of a symmetrical intermediate, such as the tropylium ion to toluene. To provide information on this point the irradiation of toluene labelled with carbon-14 is being investigated. (author)

1962-01-01

195

Ethyl gets MMT approval  

Energy Technology Data Exchange (ETDEWEB)

A federal appeals court in Washington agreed with ethyl (Richmand, VA) that it need not reregister methylcyclopentadienyl manganese (MMT), its manganese-based fuel additive. The unanimous three-judge ruling removes the last regulatory obstacle for Ethyl and compels EPA to let the company market MMT.

Stringer, J.

1995-11-01

196

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

197

Toluene pyrolysis studies and high temperature reactions of propargyl chloride  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1993-12-01

198

Methane from benzene in argon dielectric barrier discharge.  

UK PubMed Central (United Kingdom)

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.

Das TN; Dey GR

2013-03-01

199

Thermodynamics of mixtures involving some (benzene derivatives+benzonitrile)  

Energy Technology Data Exchange (ETDEWEB)

Interactions of binary mixtures involving some benzene derivatives (ethylbenzene, o-, m-, p-xylene, isopropylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and methoxybenzene) with benzonitrile were investigated in continuation of our previous studies on binary systems (benzene or toluene+benzonitrile). Heat capacities by volume unit, determined with a Picker flow calorimeter at T=298.15K, and densities, measured by using Picker vibrating densimeters at the temperatures (298.15 and 308.15)K, are reported. Measurements were made over the entire range of mole fraction. From the primary measurements, the corresponding excess quantities V{sup E} and C{sub p,m}{sup E} are obtained. The magnitude of these experimental quantities together with H{sup E} literature data is discussed in terms of the nature and type of intermolecular interactions in binary mixtures.

Calvo-Iglesias, E. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)]. E-mail: faencina@usc.es; Bravo, R. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Pintos, M. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Amigo, A. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Roux, A.H. [Thermodynamique des Solutions et des Polymeres, UMR CNRS 6003, Universite Blaise Pascal, 63177 Aubiere cedex (France); Roux-Desgranges, G. [Thermodynamique des Solutions et des Polymeres, UMR CNRS 6003, Universite Blaise Pascal, 63177 Aubiere cedex (France)

2007-04-15

200

Chemical kinetic study of the oxidation of toluene and related cyclic compounds  

Energy Technology Data Exchange (ETDEWEB)

Chemical kinetic models of hydrocarbons found in transportation fuels are needed to simulate combustion in engines and to improve engine performance. The study of the combustion of practical fuels, however, has to deal with their complex compositions, which generally involve hundreds of compounds. To provide a simplified approach for practical fuels, surrogate fuels including few relevant components are used instead of including all components. Among those components, toluene, the simplest of the alkyl benzenes, is one of the most prevalent aromatic compounds in gasoline in the U.S. (up to 30%) and is a promising candidate for formulating gasoline surrogates. Unfortunately, even though the combustion of aromatics been studied for a long time, the oxidation processes relevant to this class of compounds are still matter of discussion. In this work, the combustion of toluene is systematically approached through the analysis of the kinetics of some important intermediates contained in its kinetic submechanism. After discussing the combustion chemistry of cyclopentadiene, benzene, phenol and, finally, of toluene, the model is validated against literature experimental data over a wide range of operating conditions.

Mehl, M; Frassoldati, A; Fietzek, R; Faravelli, T; Pitz, W; Ranzi, E

2009-10-01

 
 
 
 
201

Electronic absorption spectra of alkyl derivatives of bis-benzene chromium(O) in the gas phase  

Energy Technology Data Exchange (ETDEWEB)

The authors analyze the electronic absorption and photoelectron spectra of the alkylated chromium complexes of bis-benzene and bis-toluene construct a quantum-chemical atomic model to determine ionization potentials, oscillator strengths, Rydberg constants and corrections, and various spin, dipole, and forbidden transitions allowed by the symmetry groups used for the complexes. Line widths are analyzed and tabulated.

Ketkov, S.Yu.; Domrachev, G.A.; Razuvaev, G.A.

1987-08-01

202

Estimating airborne benzene exposures from air monitoring data for mineral spirits.  

UK PubMed Central (United Kingdom)

"Low aromatics" vs. "regular" mineral spirits differ substantially in their aromatic hydrocarbon content. Mineral spirits contain benzene and other compounds that boil at temperatures below the cited boiling point range of 300 ° to 415 °F. Available published information shows that until at least 2000, the benzene content of regular mineral spirits was typically 0.1% wt/wt and at times could have been 1.0% wt/wt. The present analysis accounts for benzene's higher volatility compared to mineral spirits as a whole and applies thermodynamic principles to estimate benzene vapor exposure as a subset of measured exposure to total hydrocarbons generated by the evaporation of mineral spirits. For a scenario in which the bulk mineral spirits only partially evaporate, this analysis explains the error in assuming that the mole fraction of benzene to "everything else" is the same in the vapor and liquid phases. It is shown that for a given concentration of total hydrocarbon vapor, the benzene vapor concentration can be more than 65-fold greater during mineral spirits evaporation compared to after all the mineral spirits has evaporated. In turn, it is reasonable to expect that during the use of regular mineral spirits, containing benzene typically at 0.1% wt/wt (as applies to usage prior to 2000), benzene vapor exposures could have exceeded 1 ppm even though the mineral spirits vapor exposure did not exceed 100 ppm, the ACGIH® TLV® time-weighted average (TWA) value for mineral spirits. The same analysis can be applied to current petrochemical products, such as toluene, that contain benzene and for which the required physico-chemical information is available. The analysis provides evidence that the material safety data sheet (MSDS) for a petrochemical product containing benzene at less than 0.1% wt/wt should, pursuant to Hazard Communication Standard requirements, identify the benzene as a hazardous ingredient.

Kopstein M

2011-05-01

203

Estimating airborne benzene exposures from air monitoring data for mineral spirits.  

Science.gov (United States)

"Low aromatics" vs. "regular" mineral spirits differ substantially in their aromatic hydrocarbon content. Mineral spirits contain benzene and other compounds that boil at temperatures below the cited boiling point range of 300 ° to 415 °F. Available published information shows that until at least 2000, the benzene content of regular mineral spirits was typically 0.1% wt/wt and at times could have been 1.0% wt/wt. The present analysis accounts for benzene's higher volatility compared to mineral spirits as a whole and applies thermodynamic principles to estimate benzene vapor exposure as a subset of measured exposure to total hydrocarbons generated by the evaporation of mineral spirits. For a scenario in which the bulk mineral spirits only partially evaporate, this analysis explains the error in assuming that the mole fraction of benzene to "everything else" is the same in the vapor and liquid phases. It is shown that for a given concentration of total hydrocarbon vapor, the benzene vapor concentration can be more than 65-fold greater during mineral spirits evaporation compared to after all the mineral spirits has evaporated. In turn, it is reasonable to expect that during the use of regular mineral spirits, containing benzene typically at 0.1% wt/wt (as applies to usage prior to 2000), benzene vapor exposures could have exceeded 1 ppm even though the mineral spirits vapor exposure did not exceed 100 ppm, the ACGIH® TLV® time-weighted average (TWA) value for mineral spirits. The same analysis can be applied to current petrochemical products, such as toluene, that contain benzene and for which the required physico-chemical information is available. The analysis provides evidence that the material safety data sheet (MSDS) for a petrochemical product containing benzene at less than 0.1% wt/wt should, pursuant to Hazard Communication Standard requirements, identify the benzene as a hazardous ingredient. PMID:21476170

Kopstein, Melvyn

2011-05-01

204

New method for spectrophotometric determination of benzene in air  

Energy Technology Data Exchange (ETDEWEB)

A new spectrophotometric method for the determination of benzene in air is described. The method is based upon the nitration of benzene to m-dinitrobenzene and subsequent reduction to m-phenylenediamine. m-Phenylenediamine is determined by diazotization-coupling reaction. ..cap alpha..-Naphthol is used as a coupling reagent. Beer's law is obeyed in the range of 10-80 ..mu..g of m-dinitribenzene per 25 mL sample. The dye shows a wavelength of maximum absorption at 530 nm. The dye is stable for approx. 30 h. Toluene, the major interferent, can be separated. Beer's law, sensitivity, reproducibility, and other reaction conditions such as time, temperature, and acidity were studied. Formation of stable dye is the main advantage of the method over the butanone method for benzene, in which the colored complex is stable for only 5 min. It is possible to determine traces of benzene (0.05-0.30 ..mu..g/mL) by extracting the azo dye in 10 mL iso-amyl alcohol; this also increases the stability of the dye up to 42 h. 11 references, 4 tables.

Verma, P.; Gupta, V.K.

1984-01-01

205

Benzene hematotoxicity and leukemogenesis  

Energy Technology Data Exchange (ETDEWEB)

Eight-to-twelve-week-old male and female C57B1/6 BNL mice were exposed to air or benzene vapor in air at a concentration of 10, 25, 100, 300, or 400 ppm. Benzene at concentrations of 100 ppm or higher for 10 exposures of 6 hours per day 5 days a week produced a reduction in bone marrow cellularity and the number of pluripotent stem cells in the bone marrow. The fraction of stem cells in DNA synthesis was also increased. Exposure to 300 ppm 6 hours a day 5 days a week for 2, 4, 8, and 16 weeks produced a diminution in the stem cell levels in bone marrow which returned to those of controls 2 weeks after benzene exposure for 2 and 4 weeks, 16 weeks after exposure for 8 weeks, and to 92% of controls 25 weeks after 16 weeks of exposure. There was a more rapid return of blood lymphocytes to the control level. Mice exposed to 300 ppm for 6 hours/day, 5 days per week for 16 weeks began dying at 330 days of age, whereas no deaths were observed in sham-exposed mice until 440 days of age. The benzene-exposed mice died in two waves: the first was from 330-390 days of age, with a second wave commencing at 570 days of age. The first wave of mortality was due primarily to thymic lymphomata. The second wave was due to a mixture of nonthymic lymphomata and solid tumors. 19 references, 7 figures, 1 table.

Cronkite, E.P.; Drew, R.T.; Inoue, T.; Bullis, J.E.

1985-01-01

206

Para-methylstyrene from toluene and acetaldehyde  

Energy Technology Data Exchange (ETDEWEB)

High yields of para-methylstyrene (PMS) were obtained in this study by coupling toluene and acetaldehyde then cracking the resultant 1,1-ditolylethane (DTE) to give equimolar amounts of PMS and toluene. In the first step, a total DTE and ''trimer'' yield of 98% on toluene and 93% on acetaldehyde was obtained using 98% sulfuric acid as catalyst at 5-10/sup 0/C. In the second step, a choline chloride-offretite cracked DTE with 84.0% conversion and 91% selectivity to PMS and toluene. Additional PMS can be obtained by cracking the by-product ''trimer'' formed by coupling DTE and toluene with acetaldehyde. Zeolite Rho was as active but yielded less PMS (86%) and produced more para-ethyltoluene (PET), an undesirable by-product.

Innes, R.A.; Occelli, M.L.

1984-08-01

207

Carbon doping of MgB{sub 2} by toluene and malic-acid-in-toluene  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Both toluene and malic acid contribute carbon to MgB{sub 2}. {yields} Toluene is more effective than malic acid for transport properties. {yields} Total carbon can be measured by LECO carbon analysis. - Abstract: The decomposition of malic acid (C{sub 4}H{sub 6}O{sub 5}) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C{sub 7}H{sub 8}) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained {approx}0.4 wt.% C while the toluene/malic acid mixture had {approx}1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB{sub 2} monofilamentary wires established that the toluene/malic acid doped sample had the highest B{sub c2}. However, the toluene-only sample had the highest transport J{sub c} over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.

Bohnenstiehl, S.D., E-mail: bohnenstiehl.1@osu.ed [Center for Superconducting and Magnetic Materials, Department of Materials Science and Engineering, Ohio State University, Columbus, OH (United States); Susner, M.A.; Yang, Y.; Collings, E.W.; Sumption, M.D. [Center for Superconducting and Magnetic Materials, Department of Materials Science and Engineering, Ohio State University, Columbus, OH (United States); Rindfleisch, M.A.; Boone, R. [Hyper Tech Research, Inc., 539 Industrial Mile Road, Columbus, OH 43228 (United States)

2011-02-15

208

Membrane bioreactor for TCE cometabolism with toluene  

Energy Technology Data Exchange (ETDEWEB)

Biofilters have been of limited use for cometabolism of chlorinated organic compounds such as trichloroethylene (TCE). In cometabolism, cosubstrates must be available as primary carbon and energy sources and to induce synthesis of necessary enzymes to cometabolize the target compound. The cosubstrates often inhibit cometabolism of the target compound, however. A hollow fiber membrane bioreactor was investigated that allowed for addition of cosubstrates to the microbial population while maintaining low enough concentrations to prevent inhibition. The system involves a bundle of polypropylene fibers through which VOC contaminated air passes. The fibers are immersed in a recirculating nutrient/cosubstrate solution. This system is suited to cometabolism as the cosubstrate is diluted into the nutrient solution. A mixed culture of toluene degraders was developed from a municipal wastewater mixed liquor sample. Batch experiments were performed to determine whether the culture could cometabolize TCE, the toluene degradation rate kinetics and the extent of toluene and TCE inhibition. In batch experiments, TCE was cometabolized only after toluene was degraded. No inhibition or injury to the toluene degrading ability was observed at up to 15 mg/L toluene or up to 1.5 mg/L TCE. The culture was inoculated into the hollow-fiber membrane bioreactor. Initially toluene was supplied to the reactor at a concentration of 200 ppm to build a sufficient biomass density on the fibers. After steady-state toluene removal was achieved, a toluene-TCE mixture was added to the reactor. This paper investigates if addition of toluene to the reactor in gas or liquid phase is more favorable for cometabolism, the use of a pulsing strategy, and the benefits of including a simple biomass removal method.

Dolasa, A.R.; Ergas, S.J.

1999-07-01

209

Comparative studies on toluene removal and pressure drop in biofilters using different packing materials.  

UK PubMed Central (United Kingdom)

To select the best available packing material for malodorous organic gases such as toluene and benzene, biofilter performance was compared in biofilters employed different packing materials including porous ceramic (celite), Jeju scoria (lava), a mixture of granular activated carbon (GAC) and celite (GAC/celite), and cubic polyurethane foam (PU). A toluene-degrading bacterium, Stenotrophomonas maltophilia T3-c, was used as the inoculum. The maximum elimination capacities in the celite, lava, and GAC/celite biofilters were 100, 130, and 110 gm(-3) hr(-1), respectively. The elimination capacity for the PU biofilter was approximately 350 g m(-3) hr(-1) at an inlet loading of approximately 430 g m(-3) hr(-1), which was 2 to 3.5 times higher than for the other biofilters. The pressure drop gradually increased in the GAC/ celite, celite and lava biofilters after 23 day due to bacterial over-growth, and the toluene removal efficiency remarkably decreased with increasing pressure drop. Backwashing method was not effective for the control of biomass in these biofilters. In the PU biofilter however, backwashing allowed maintenance of a pressure drop of 1 to 3 mm H2O m(-1) and a removal efficiency of > 80%, indicating that the PU was the best packing material for toluene removal among the packing materials tested.

Ryu HW; Kim SJ; Cho KS

2010-05-01

210

Benzene vapor recovery and processing  

International Nuclear Information System (INIS)

[en] The National Emissions Standards for Hazardous Air Pollutants, or NESHAPs, have provided a powerful motivation for interest in, and attention to, benzene vapor emissions in recent times. Benzene and its related aromatics are volatile organic compounds (VOCs), which marks them for surveillance as potential contributors to air pollution. In addition, benzene is a suspected carcinogen, which applies a special urgency to its control. The regulations governing the control of benzene emissions were issued as Title 40, Code of Federal Regulations, Part 61, subpart Y (Storage Vessels); subpart BB (Transfer Operations); and subpart FF (Waste Operations). These regulations specify very particular emission reduction guidelines for various generating sources. The problem in the hydrocarbon processing industry is to identify significant sources of benzene vapors in plants, and then to collect and process these vapors in an environmentally acceptable manner. This paper discusses various methods for collecting benzene fumes in these facilities

1991-01-01

211

Composition of toluene-degrading microbial communities from soil at different concentrations of toluene  

Energy Technology Data Exchange (ETDEWEB)

Toluene-degrading bacteria were isolated from hydrocarbon-contaminated soil by incubating liquid enrichment cultures and agar plate cultures in desiccators in which the vapor pressure of toluene was controlled by dilution with vacuum pump oil. Incubation in desiccators equilibrated with either 100, 10, or 1% (wt/wt) toluene in vacuum pump oil and testing for genomic cross-hybridization resulted in four genomically distinct strains (standards) capable of growth on toluene (strains Cstd1, Cstd2, and Cstd5, and Cstd7). The optimal toluene concentrations for growth of these standards on plating media differed considerably. Cstd1 grew best in an atmosphere equilibrated with 0.1% (wt/wt) toluene, but Cstd5 failed to grow in this atmosphere. Conversely, Cstd5 grew well in the presence of 10% (wt/wt) toluene, which inhibited growth of Cstd1. 16S ribosomal DNA sequencing and cross-hybridization analysis indicated that both Cstd1 and Cstd5 are members of the genus Pseudomonas. An analysis of the microbial communities in soil samples that were incubated with 10% (wt/wt) toluene with reverse sample genome probing indicated that Pseudomonas strain Cstd5 was the dominant community member. However, incubation of soil samples with 0.1% (wt/wt) toluene resulted in a community that was dominated by Pseudomonas strain Q7, a toluene degrader that has been described previously. Q7 was not able to grow by itself in an atmosphere equilibrated with 0.1% (wt/wt) toluene but grew efficiently in coculture with Cstd1, suggesting that toluene or metabolic derivatives of toluene were transferred from Cstd1 to Q7.

Hubert, C.; Shen, Y.; Voordouw, G. (Univ. of Calgary, Alberta (Canada). Dept. of Biological Sciences)

1999-07-01

212

(Z)-Methyl 2-[(2-eth­oxy-6-formyl­phen­oxy)meth­yl]-3-(4-ethyl­phen­yl)acrylate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compound, C22H24O5, consists of two substituted benzene rings linked by an ethyl acrylate group. The dihedral angle between the two benzene rings is 58.39?(7)°. The crystal packing is governed by two C—H?O inter­actions, one of which forms centrosymmetric dimers with a graph-set descriptor...

Gangadharan, Rajeswari; Sethusankar, K.; Selvakumar, Raman; Bakthadoss, Manickam

213

Studies of TPB dissolved in Toluene  

Science.gov (United States)

Scintillation light in liquid argon calorimeters is produced at 128 nm. This must be shifted to the visible so that the light can be observed by phototubes. A traditional method for accomplishing this is to dissolve Tetraphenyl butadiene and plastic into toluene, and then use this mixture to coat surfaces. After the toluene evaporates, the TPB in the thin plastic skin will shift the light. In both the WARP and MicroBooNE experiments, it has been observed that impure TPB will react with Toluene when exposed to light turning the mixture green. We report on this effect in this talk. )

Jerry, Ruel; Winslow, Lindley; Conrad, Janet

2010-02-01

214

Benzene oxidation coupled to sulfate reduction  

Science.gov (United States)

Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to I ??M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [14C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as 14CO2. Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of 14CO2 from [14C]benzene. Benzene metabolism stopped when the sediments became sulfate depleted, and benzene uptake resumed when sulfate was added again. The stoichiometry of benzene uptake and sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for benzene oxidation. Isotope trapping experiments performed with [14C]benzene revealed that there was no production of such potential extracellular intermediates of benzene oxidation as phenol, benzoate, p-hydroxybenzoate, cyclohexane, catechol, and acetate. The results demonstrate that benzene can be oxidized in the absence of O2, with sulfate serving as the electron acceptor, and suggest that some sulfate reducers are capable of completely oxidizing benzene to carbon dioxide without the production of extracellular intermediates. Although anaerobic benzene oxidation coupled to chelated Fe(III) has been documented previously, the study reported here provides the first example of a natural sediment compound that can serve as an electron acceptor for anaerobic benzene oxidation.

Lovley, D. R.; Coates, J. D.; Woodward, J. C.; Phillips, E. J. P.

1995-01-01

215

N-(2,6-Diisopropyl-phen-yl)formamide toluene 0.33-solvate.  

UK PubMed Central (United Kingdom)

The crystal packing of the title compound, C(13)H(19)NO·0.33C(7)H(8), shows a channel at [001], which contains grossly disordered toluene solvent mol-ecules. The angle between the benzene ring and the mean plane of the formamide group is 71.1?(1)°. The amide groups of neighbouring mol-ecules are connected by N-H?O hydrogen bonds, forming 2(1) helical chains propagating along [001]. Mol-ecules are also connected by weak inter-molecular C-H?O hydrogen bonds, forming 6(1) helices.

Berger M; Bats JW; Auner N

2012-05-01

216

N-(2,6-Diisopropylphenyl)formamide toluene 0.33-solvate  

Directory of Open Access Journals (Sweden)

Full Text Available The crystal packing of the title compound, C13H19NO·0.33C7H8, shows a channel at [001], which contains grossly disordered toluene solvent molecules. The angle between the benzene ring and the mean plane of the formamide group is 71.1?(1)°. The amide groups of neighbouring molecules are connected by N—H...O hydrogen bonds, forming 21 helical chains propagating along [001]. Molecules are also connected by weak intermolecular C—H...O hydrogen bonds, forming 61 helices.

Matthias Berger; Jan W. Bats; Norbert Auner

2012-01-01

217

Hematotoxicity and carcinogenicity of benzene  

Energy Technology Data Exchange (ETDEWEB)

The hematotoxicity of benzene exposure has been well known for a century. Benzene causes leukocytopenia, thrombocytopenia, pancytopenia, etc. The clinical and hematologic picture of aplastic anemia resulting from benzene exposure is not different from classical aplastic anemia; in some cases, mild bilirubinemia, changes in osmotic fragility, increase in lactic dehydrogenase and fecal urobilinogen, and occasionally some neurological abnormalities are found. Electromicroscopic findings in some cases of aplastic anemia with benzene exposure were similar to those observed by light microscopy. Benzene hepatitis-aplastic anemia syndrome was observed in a technician with benzene exposure. Ten months after occurrence of hepatitis B, a severe aplastic anemia developed. The first epidemiologic study proving the leukemogenicity of benzene was performed between 1967 and 1973 to 1974 among shoe workers in Istanbul. The incidence of leukemia was 13.59 per 100,000, which is a significant increase over that of leukemia in the general population. Following the prohibition and discontinuation of the use of benzene in Istanbul, there was a striking decrease in the number of leukemic shoe workers in Istanbul. In 23.7% of the series, consisting of 59 leukemic patients with benzene exposure, there was a preceding pancytopenic period. Furthermore, a familial connection was found in 10.2% of them. The 89.8% of the series showed the findings of acute leukemia. The possible factors that may determine the types of leukemia in benzene toxicity are discussed. The possible role of benzene exposure is presented in the development of malignant lymphoma, multiple myeloma, and lung cancer.

Aksoy, M. (Scientific and Technical Research Council of Turkey, Kocaeli (Turkey))

1989-07-01

218

Determination of conformational and spectroscopic features of ethyl trans-alfa-cyano-3-indole-acrylate compound: an experimental and quantum chemical study.  

Science.gov (United States)

The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and non-linear optical properties of ethyl trans-alfa-cyano-3-indole-acrylate (C(14)H(12)N(2)O(2)) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000-400 cm(-1) and 4000-10 cm(-1), respectively. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The (1)H, (13)C and DEPT NMR spectra were recorded in DMSO solution, and gauge-invariant atomic orbitals (GIAO) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were recorded in the range of 200-800 nm in various solvents of different polarity (acetone, benzene, chlorobenzene, chloroform, DMSO, ethanol, methanol and toluene). Solvent effects were calculated using TD-DFT and CIS method. To investigate the non-linear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations. PMID:23274474

Cinar, Mehmet; Karabacak, Mehmet

2012-12-05

219

Determination of conformational and spectroscopic features of ethyl trans-alfa-cyano-3-indole-acrylate compound: an experimental and quantum chemical study.  

UK PubMed Central (United Kingdom)

The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and non-linear optical properties of ethyl trans-alfa-cyano-3-indole-acrylate (C(14)H(12)N(2)O(2)) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000-400 cm(-1) and 4000-10 cm(-1), respectively. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The (1)H, (13)C and DEPT NMR spectra were recorded in DMSO solution, and gauge-invariant atomic orbitals (GIAO) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were recorded in the range of 200-800 nm in various solvents of different polarity (acetone, benzene, chlorobenzene, chloroform, DMSO, ethanol, methanol and toluene). Solvent effects were calculated using TD-DFT and CIS method. To investigate the non-linear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

Cinar M; Karabacak M

2013-03-01

220

SYNTHESIS OF PROPYLBENZENE FROM TOLUENE AND ETHYLENE  

UK PubMed Central (United Kingdom)

Methods are provided for producing alkylbenzenes, such as propylbenzene, from aromatics, such as toluene, and alkenes, such as ethylene. Such methods comprise combining the toluene with about 100 ppm to about 350 ppm water and alkali metal catalyst, activating the catalyst at about 18O DEG C. to about 220 DEG C., adding the ethylene and conducting the synthesis reaction at about 130 DEG C. to about 15O DEG C.

BELMONT STEPHEN E; NELSON ROBERT W; CURTIS CHRISTOPHER A

 
 
 
 
221

Synthesis of propylbenzene from toluene and ethylene  

UK PubMed Central (United Kingdom)

Methods are provided for producing alkylbenzenes, such as propylbenzene, from aromatics, such as toluene, and alkenes, such as ethylene. Such methods comprise combining the toluene with about 100 ppmto about 350 ppm water and alkali metal catalyst, activating the catalyst at about 18O DEG C to about 220 DEG C, adding the ethylene and conducting the synthesis reaction at about 130 DEG C to about 15O DEG C.

BELMONT STEPHEN E; NELSON ROBERT W; CURTIS CHRISTOPHER A

222

Health assessment of toluene in California drinking water  

Energy Technology Data Exchange (ETDEWEB)

This report reviews existing literature pertinent to the health risk posed by the use of toluene-contaminated drinking water. Also included in the study is an estimate of the toluene exposure of California residents based on the most recent data on toluene concentrations in California drinking water supplies. The concentration of toluene in drinking water that may cause adverse health effects is delineated.

Reed, N.; Reed, W.; Beltran, L.; Li, R.; Encomienda, I.

1989-03-08

223

Toluene-induced ototoxicity by subcutaneous administration  

Energy Technology Data Exchange (ETDEWEB)

Inhalation exposure of rats to toluene causes irreversible hearing loss (e.g., Pryor et al.). To determine whether noise emanating from the inhalation system was a major contributing factor and whether exposure by a noninhalation route would cause a similar effect, weanling, male Fischer-344 rats were injected SC twice daily in a quiet environment with PEG-300 (control) or with 1.5 or 1.7 g/kg of toluene for 7 days. After being trained to perform a multisensory conditioned avoidance response (CAR) task, tone intensity-response functions were generated at 4, 8, 12, and 20 kHz, and behavioral auditory response thresholds were estimated. Toluene caused a dose-related hearing loss at frequencies of 8 kHz and above, with no effect on performance of the CAR in response to light, nonaversive footshock, or the 4-kHz tone. The similarity of this effect to that observed following inhalation exposure indicates that noise is not a major factor in the toluene-induced hearing loss, although possible interactions between noise and toluene remain to be investigated. These results also demonstrate that direct penetration of the toluene vapors through the external ear structure, as might occur during inhalation exposure, is not a necessary condition for inducing the hearing loss.

Pryor, G.T.; Howd, R.A.

1986-01-01

224

N-[(E)-(9-Ethyl-9H-carbazol-3-yl)methylidene]aniline  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C21H18N2, was obtained as the product of the reaction between 9-ethyl-9H-carbazole-3-carbaldehyde and aniline in ethanol. The crystal packing is stabilized mainly by C—H...? interactions between the carbazole benzene rings and the methylene H atoms.

Nuray Yeksan; Ece Uzkara; Orhan Zeybek; Erol Asker

2010-01-01

225

1-Ethyl-3-(2,4,6-trimethylphenyl)imidazolium tetrafluoroborate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C14H19N2+·BF4?, was obtained by reaction of 1-ethyl-3-(2,4,6-trimethylphenyl)imidazolium tetrafluoroborate with sodium tetrafluoroborate. The imidazole ring makes a dihedral angle of 78.92?(13)° with the benzene ring.

Jin-Tao Guan; Jian-Guo Hou; Zhi-Yong Zhang; Si-Yin Zhao

2010-01-01

226

Solvent extraction separation of thorium(IV) with 2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester (PC-88A)  

International Nuclear Information System (INIS)

Solvent extraction separation of thorium(IV) has been carried out with 2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester (PC-88A) in toluene from nitric acid media. Various parameters like acid concentration, reagent concentration, diluent, stripping agent, equilibrium time and diverse ions affecting the extraction of thorium(IV) were studied systematically. Thorium was quantitatively extracted from 0.1-1.0 M nitric acid with 1 x 10-2 M PC-88A in toluene. It was then stripped out from the organic phase with 10 M nitric acid and determined spectrophotometrically by thoron method. Further, the separation of thorium was carried out from uranium, lanthanum and cerium depending on the difference in the extraction behaviour of these metals with PC-88A. (author)

1999-01-01

227

Protein Engineering of Toluene Monooxygenases for Synthesis of Chiral Sulfoxides?  

Science.gov (United States)

Enantiopure sulfoxides are valuable asymmetric starting materials and are important chiral auxiliaries in organic synthesis. Toluene monooxygenases (TMOs) have been shown previously to catalyze regioselective hydroxylation of substituted benzenes and phenols. Here we show that TMOs are also capable of performing enantioselective oxidation reactions of aromatic sulfides. Mutagenesis of position V106 in the ?-hydroxylase subunit of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 and the analogous position I100 in toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 improved both rate and enantioselectivity. Variant TomA3 V106M of TOM oxidized methyl phenyl sulfide to the corresponding sulfoxide at a rate of 3.0 nmol/min/mg protein compared with 1.6 for the wild-type enzyme, and the enantiomeric excess (pro-S) increased from 51% for the wild type to 88% for this mutant. Similarly, T4MO variant TmoA I100G increased the wild-type oxidation rate by 1.7-fold, and the enantiomeric excess rose from 86% to 98% (pro-S). Both wild-type enzymes showed lower activity with methyl para-tolyl sulfide as a substrate, but the improvement in the activity and enantioselectivity of the mutants was more dramatic. For example, T4MO variant TmoA I100G oxidized methyl para-tolyl sulfide 11 times faster than the wild type did and changed the selectivity from 41% pro-R to 77% pro-S. A correlation between regioselectivity and enantioselectivity was shown for TMOs studied in this work. Using in silico homology modeling, it is shown that residue I100 in T4MO aids in steering the substrate into the active site at the end of the long entrance channel. It is further hypothesized that the main function of V106 in TOM is the proper positioning or docking of the substrate with respect to the diiron atoms. The results from this work suggest that when the substrate is not aligned correctly in the active site, the oxidation rate is decreased and enantioselectivity is impaired, resulting in products with both chiral configurations.

Feingersch, Roi; Shainsky, Janna; Wood, Thomas K.; Fishman, Ayelet

2008-01-01

228

Construction and comparison of fluorescence and bioluminescence bacterial biosensors for the detection of bioavailable toluene and related compounds  

Energy Technology Data Exchange (ETDEWEB)

Environmental pollution with petroleum products such as benzene, toluene, ethylbenzene, and xylenes (BTEX) has garnered increasing awareness because of its serious consequences for human health and the environment. We have constructed toluene bacterial biosensors comprised of two reporter genes, gfp and luxCDABE, characterized by green fluorescence and luminescence, respectively, and compared their abilities to detect bioavailable toluene and related compounds. The bacterial luminescence biosensor allowed faster and more-sensitive detection of toluene; the fluorescence biosensor strain was much more stable and thus more applicable for long-term exposure. Both luminescence and fluorescence biosensors were field-tested to measure the relative bioavailability of BTEX in contaminated groundwater and soil samples. The estimated BTEX concentrations determined by the luminescence and fluorescence bacterial biosensors were closely comparable to each other. Our results demonstrate that both bacterial luminescence and fluorescence biosensors are useful in determining the presence and the bioavailable fractions of BTEX in the environment. - The choice of reporter genes for toluene bacterial biosensors to determine BTEX bioavailability is case-specific.

Li, Y.-F. [Department of Bioenvironmental Systems Engineering, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Li, F.-Y. [Department of Chemistry, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Ho, C.-L. [Division of Wood Cellulose, Taiwan Forestry Research Institute, 53 Nanhai Road, Taipei 100, Taiwan (China); Liao, V.H.-C. [Department of Bioenvironmental Systems Engineering, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)], E-mail: vivianliao@ntu.edu.tw

2008-03-15

229

Construction and comparison of fluorescence and bioluminescence bacterial biosensors for the detection of bioavailable toluene and related compounds  

International Nuclear Information System (INIS)

[en] Environmental pollution with petroleum products such as benzene, toluene, ethylbenzene, and xylenes (BTEX) has garnered increasing awareness because of its serious consequences for human health and the environment. We have constructed toluene bacterial biosensors comprised of two reporter genes, gfp and luxCDABE, characterized by green fluorescence and luminescence, respectively, and compared their abilities to detect bioavailable toluene and related compounds. The bacterial luminescence biosensor allowed faster and more-sensitive detection of toluene; the fluorescence biosensor strain was much more stable and thus more applicable for long-term exposure. Both luminescence and fluorescence biosensors were field-tested to measure the relative bioavailability of BTEX in contaminated groundwater and soil samples. The estimated BTEX concentrations determined by the luminescence and fluorescence bacterial biosensors were closely comparable to each other. Our results demonstrate that both bacterial luminescence and fluorescence biosensors are useful in determining the presence and the bioavailable fractions of BTEX in the environment. - The choice of reporter genes for toluene bacterial biosensors to determine BTEX bioavailability is case-specific

2008-01-01

230

Ethyl alcohol production  

Energy Technology Data Exchange (ETDEWEB)

Recent price increases and temporary shortages of petroleum products have caused farmers to search for alternate sources of fuel. The production of ethyl alcohol from grain is described and the processes involved include saccharification, fermentation and distillation. The resulting stillage has potential as a livestock feed.

Hofman, V.; Hauck, D.

1980-11-01

231

Device and process for continuously producing 2-ethyl anthracene quinone in channelization way  

UK PubMed Central (United Kingdom)

The invention discloses a device and a process for continuously producing 2-ethyl anthracene quinone in a channelization way. The device is shown in the figure, and the process is specifically shown as below: putting fuming sulfuric acid in a second storage tank putting solid raw material 2-(4- ethyl benzene formoxyl) benzoic acid in a storage tank I rising the temperature to 125-190 DEG C to keep the 2-(4- ethyl benzene formoxyl) benzoic acid in a liquid state rapidly and evenly mixing the 2-(4- ethyl benzene formoxyl) benzoic acid in the storage tank I and the fuming sulfuric acid in a storage tank II in a Y-type jet mixer and then filling the mixture in a pipe-type reactor, controlling the reaction temperature in the pipe-type to be 120-180 DEG C and the reaction time to be 2-10 min and hydrolyzing the obtained reaction liquid in a hydrolization pot to separate out the product 2-ethyl anthracene quinone. The device has the advantages of simplicity, high process safety, easy control of reaction conditions, realization of serialization production, productivity reaching more than 90 percent, stable product quality and large scale industrial production by only less investment.

WEIKE SU; JIANJUN LI; SHOUWANG LIN; CANLIANG JIN; DONGMING PAN

232

Aerobic cometabolism of trichloroethene and cis-dichloroethene with benzene and chlorinated benzenes as growth substrates.  

Science.gov (United States)

Using inoculum from a microcosm study that exhibited aerobic transformation of cis-1,2-dichloroethene (cDCE) and trichloroethene (TCE) commensurate with biodegradation of monoaromatic compounds, enrichment cultures were developed by providing benzene, chlorobenzene (CB), dichlorobenzene (DCB) isomers and 1,2,4-trichlorobenzene as carbon and energy sources. Isolates that grow on benzene, CB, 1,2-DCB and 1,3-DCB were identified as Rhodococcus, Ralstonia, Variovorax and Ralstonia spp., respectively. Cometabolic transformation of cDCE and TCE by resting cells was demonstrated. Transformation capacities (T(c)=0.47-1.0 ?g TCE mg(-1)biomass; 1.3-5.3 ?g cDCE mg(-1)biomass), transformation yields (T(y)=0.18-0.27 ?g TCE mg(-1)substrate; 0.46-2.1 ?g cDCE mg(-1)substrate), and pseudo-first-order cometabolic degradation rate constants (0.00081-0.0031 L mg TCE(-1)d(-1); 0.0012-0.030 L mg cDCE(-1)d(-1)) for resting cells grown on benzene, CB, 1,2-DCB and 1,3-DCB were generally lower in comparison to phenol and toluene-grown isolates. Cometabolic transformation of cDCE and TCE also occurred while the cultures concurrently consumed their growth substrate (T(c)(')=0.15-0.33 ?g TCE mg(-1)biomass; 4.9-11 ?g cDCE mg(-1)biomass; T(y)(')=0.06-0.11 ?g TCE mg(-1)substrate; 1.7-4.6 ?g cDCE mg(-1)substrate), a condition that is more likely to be encountered in situ compared to cometabolic transformations by resting cells. This study is the first to report transformation rates, capacities, and yields for cometabolism of cDCE and TCE during aerobic growth on benzene, CB, 1,2-DCB and 1,3-DCB. This type of information is needed to predict the potential for natural attenuation when these compounds occur as co-contaminants. PMID:21531438

Elango, Vijai; Kurtz, Harry D; Freedman, David L

2011-04-30

233

Ultraselective and sensitive detection of xylene and toluene for monitoring indoor air pollution using Cr-doped NiO hierarchical nanostructures.  

UK PubMed Central (United Kingdom)

Ultraselective and sensitive detection of xylene and toluene with minimum interferences of other indoor air pollutants such as benzene, ethanol, and formaldehyde is achieved using NiO hierarchical nanostructures doped with Cr. Pure and 1.15-2.56 at% Cr-doped NiO flower-like hierarchical nanostructures assembled from nanosheets are prepared by a simple solvothermal reaction and their gas sensing characteristics toward o-xylene and toluene gases are investigated. The 1.15 at% Cr-doped NiO hierarchical nanostructures show high responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 11.61 and 7.81, respectively) and negligible cross-responses to 5 ppm of benzene, formaldehyde, ethanol, hydrogen, and carbon monoxide. However, pure NiO nanostructures show low responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 2.01 and 1.14, respectively) and no selectivity toward any specific gas is observed. Significant enhancement of the response and selectivity to o-xylene and toluene is attributed to the decrease in the hole concentration in NiO and the catalytic oxidation of methyl groups by Cr doping.

Kim HJ; Yoon JW; Choi KI; Jang HW; Umar A; Lee JH

2013-08-01

234

Analysis of structure, function, and activity of a benzene-degrading microbial community.  

UK PubMed Central (United Kingdom)

We identified phylotypes performing distinct functions related to benzene degradation in complex microbial biofilms from an aerated treatment pond containing coconut textile. RNA- and protein-stable isotope probing (SIP) and compound-specific stable isotope analysis were applied to delineate bacteria and predominant pathways involved in the degradation of benzene. In laboratory microcosms, benzene was degraded at rates of ? 11 ?M per day and per gram coconut textile under oxic conditions. Carbon isotope fractionation with isotopic enrichment factors (?) of -0.6 to -1‰ and no significant hydrogen isotope fractionation indicated a dihydroxylation reaction for the initial ring attack. The incubation with [(13)C?]-benzene led to (13)CO? formation accompanied by (13)C-labeling of RNA and proteins of the active biomass. Phylogenetic analysis of the (13)C-labeled RNA revealed that phylotypes related to Zoogloea, Ferribacterium, Aquabacterium, and Hydrogenophaga within the Betaproteobacteria predominantly assimilated carbon from benzene. Although the phylogenetic classification of identified (13)C-labeled proteins was biased by the incomplete metagenome information of public databases, it matched with RNA-SIP results at genus level. The detection of (13)C-labeled proteins related to toluene dioxygenase and catechol 2,3-dioxygenase suggests benzene degradation by a dihydroxylation pathway with subsequent meta-cleavage of formed catechol.

Jechalke S; Franchini AG; Bastida F; Bombach P; Rosell M; Seifert J; von Bergen M; Vogt C; Richnow HH

2013-07-01

235

Analysis of structure, function, and activity of a benzene-degrading microbial community.  

Science.gov (United States)

We identified phylotypes performing distinct functions related to benzene degradation in complex microbial biofilms from an aerated treatment pond containing coconut textile. RNA- and protein-stable isotope probing (SIP) and compound-specific stable isotope analysis were applied to delineate bacteria and predominant pathways involved in the degradation of benzene. In laboratory microcosms, benzene was degraded at rates of ? 11 ?M per day and per gram coconut textile under oxic conditions. Carbon isotope fractionation with isotopic enrichment factors (?) of -0.6 to -1‰ and no significant hydrogen isotope fractionation indicated a dihydroxylation reaction for the initial ring attack. The incubation with [(13)C?]-benzene led to (13)CO? formation accompanied by (13)C-labeling of RNA and proteins of the active biomass. Phylogenetic analysis of the (13)C-labeled RNA revealed that phylotypes related to Zoogloea, Ferribacterium, Aquabacterium, and Hydrogenophaga within the Betaproteobacteria predominantly assimilated carbon from benzene. Although the phylogenetic classification of identified (13)C-labeled proteins was biased by the incomplete metagenome information of public databases, it matched with RNA-SIP results at genus level. The detection of (13)C-labeled proteins related to toluene dioxygenase and catechol 2,3-dioxygenase suggests benzene degradation by a dihydroxylation pathway with subsequent meta-cleavage of formed catechol. PMID:23398624

Jechalke, Sven; Franchini, Alessandro G; Bastida, Felipe; Bombach, Petra; Rosell, Mónica; Seifert, Jana; von Bergen, Martin; Vogt, Carsten; Richnow, Hans H

2013-03-11

236

Sorption of benzene and toluene by poly(tetrafluoroethylene) during headspace analysis  

Energy Technology Data Exchange (ETDEWEB)

The determination of physical properties by gas chromatographic headspace analysis does not provide for cancellation of errors caused by sample adsorption or absorption. Caution must be exercised to carefully quantify the amount of solute absorbed by the polytetrafluoroethylene coating on septa and stirring bars. An alternative approach would be to use alumina and glass coatings. 5 references, 1 table.

Keeley, D.F.; Hoffpauir, M.A.; Meriwether, J.R.

1986-05-01

237

Quantitation methods for the determination of benzene, toluene, ethylbenzene and xylenes in oil contaminated soils  

Energy Technology Data Exchange (ETDEWEB)

Some pretreatment methods for the determination of BTEX content in oil contaminated soil, such as solvent extraction with mechanical shaking, purge and trap and solid phase micro-extraction, were studied. Prepared samples were fine clay, loam and coarse sand which were series of particle size. Those samples were dried in 120 deg.C oven or wetted by adding some reagent water. After then, they were contaminated by spiking BTEX. The results showed that extraction limits and linear dynamic ranges of different extraction methods represented very large differences. So appropriate pretreatment methods were applied to the soil types and BTEX content. (author). 4 refs., 5 tabs.

Jeon, Chi-Wan; Lee, Jung-Hwa; Kim, Sang-Yeon; Choi, Byeng-Ihn [Korea Institute of Geoscience and Mineral Resources, Taejeon(Korea)

2001-06-01

238

Exposure to indoor air pollutants (polycyclic aromatic hydrocarbons, toluene, benzene) in Mexican indigenous women.  

UK PubMed Central (United Kingdom)

UNLABELLED: Indoor air pollution is considered to be a serious public health issue in Mexico; therefore, more studies regarding this topic are necessary. In this context, we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds in: (i) women who use firewood combustion (indoor) for cooking and heating using traditional open fire; (ii) women who use firewood combustion (outdoor) for cooking and heating using traditional open fire; and (iii) women who use LP gas as the principal energy source. We studied 96 healthy women in San Luis Potosi, México. Urine samples were collected, and analyses of the following urinary exposure biomarkers were performed by high-performance liquid chromatography: 1-hydroxypyrene (1-OHP), trans, trans-muconic acid, and hippuric acid (HA). The highest levels of 1-OHP, trans, trans-muconic acid, and HA were found in communities where women were exposed to indoor biomass combustion smoke (or products; geometric mean ± s.d., 3.98 ± 5.10 ?mol/mol creatinine; 4.81 ± 9.60 ?g/l 1-OHP; 0.87 ± 1.78 mg/g creatinine for trans, trans-muconic acid; and 1.14 ± 0.91 g/g creatinine for HA). Our findings indicate higher exposure levels to all urinary exposure biomarkers studied in women who use indoor firewood combustion for cooking and heating (using traditional open fire). PRACTICAL IMPLICATIONS: High mean levels of 1-hydroxypyrene, t,t-muconic acid, and hippuric acid were found in women who use firewood combustion (indoor) for cooking and heating using traditional open fire and taking into account that millions of women and children in Mexico are living in scenarios similar to those studied in this report, the assessment of health effects in women and children exposed to polycyclic aromatic hydrocarbons and volatile organic compounds is urgently needed. Moreover, it is immediately necessary an intervention program to reduce exposure.

Pruneda-Álvarez LG; Pérez-Vázquez FJ; Salgado-Bustamante M; Martínez-Salinas RI; Pelallo-Martínez NA; Pérez-Maldonado IN

2012-04-01

239

(E,E,E)-1,3,5-Tris[4-(acetylsulfanyl)styryl]benzene toluene hemisolvate  

DEFF Research Database (Denmark)

The first crystal structure of a three-terminal sulfur end-capped oligophenylenevinylene, C36H30O3S3 x 0.5C7H8, has been determined at 122 (1) K. The molecular threefold symmetry is not utilized in the crystal structure. It is confirmed that the double bonds have been fully transformed into a trans configuration by iodine treatment.

SØrensen, Henning Osholm; Magnussen, Magnus

2005-01-01

240

REFORMATE BENZENE REDUCTION VIA TRANSALKYLATION  

UK PubMed Central (United Kingdom)

A process for reducing benzene content in a reformate stream, including: fractionating a full range reformate comprising benzene, C7 to C9 monoalkyl aromatics, and C1O+ polyalkyl aromatics into at least three fractions including a light reformate fraction comprising the benzene a medium reformate fraction comprising the C7 to C9 monoalkyl aromatics and a heavy reformate fraction comprising the C10+ polyalkyl aromatics feeding the light reformate fraction, the heavy reformate fraction and a transalkylation catalyst to a transalkylation reaction zone contacting the light fraction and the heavy fraction in presence of the transalkylation catalyst in the transalkylation reaction zone to react at least a portion of the benzene with C1O+ polyalkyl aromatics to form monoalkyl aromatics separating an effluent from the transalkylation reaction zone to form a catalyst fraction and a liquid fraction comprising the monoalkyl aromatics.

ROCK KERRY L; BOYER CHRISTOPHER C; SMITH LAWRENCE A

 
 
 
 
241

Chemical Kinetic Study of Toluene Oxidation  

Energy Technology Data Exchange (ETDEWEB)

A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. A detailed chemical-kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels, toluene decomposition reactions and the benzyl + 0 reaction. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Under nonpremixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations are performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in nonpremixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. For both premixed and nonpremixed systems, sensitivity analysis was used to identify the reaction rate constants that control the overall rate of oxidation in each of the systems considered. Under shock tube conditions, the reactions that influence ignition delay time are H + O{sub 2} chain branching, the toluene decomposition reaction to give an H atom, and the toluene + H abstraction reaction. The reactions that influence autoignition in nonpremixed systems involve the benzyl + HO{sub 2} reaction and the phenyl + O{sub 2} reaction.

Pitz, W J; Seiser, R; Bozzelli, J W; Seshadri, K; Chen, C-J; Da Costa, I; Fournet, R; Billaud, F; Battin-Leclerc, F; Westbrook, C K

2001-12-17

242

Determination of (BTEX) of the gasoline's combustion in Ecuador  

International Nuclear Information System (INIS)

The contents of benzene, toluene, ethyl benzene and xylenes (BTEX) were determined and quantified in the gasoline's combustion on an internal combustion engine. Gas chromatography with flame ionization detector were used for chemical determinations

1998-01-01

243

Toluene degradation products in simulated atmospheric conditions  

Energy Technology Data Exchange (ETDEWEB)

The oxidation products of toluene in simulated atmospheric conditions have been determined in detail. The products identified are listed and their probable formation and destruction mechanisms are outlined. The significance of the results for pollution control are briefly discussed. 24 references.

Dumdei, B.E.; Obrien, R.J.

1984-09-20

244

Ethyl 1-acetyl-1H-indole-3-carboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C13H13NO3, was synthesized by acetylation of ethyl 1H-indole-3-carboxylate. The aromatic ring system of the molecule is essentially planar, but the saturated ethyl group is also located within this plane and the overall r.m.s. deviation from planarity is only 0.034?Å. Pairs of C—H...O interactions connect molecules into chains along the diagonal of the unit cell. Molecules also form weakly connected dimers via ?...? stacking interactions of the indole rings with centroid–centroid separations of 3.571?(1)?Å. C—H...? interactions between methylene and methyl groups and the indole and benzene ring complete the directional intermolecular interactions found in the crystal structure.

Tasneem Siddiquee; Shahid Islam; Dennis Bennett; Matthias Zeller; Mahmun Hossain

2009-01-01

245

Reproductive and developmental toxicity of toluene: a review.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Toluene is a widely used industrial solvent, and humans may also have high exposures to toluene from the deliberate inhalation ("sniffing") of paint reducer, paint thinner, or paint for their narcotic effects. A number of case reports describe neonatal effects that have been attributed to toluene ab...

Donald, J M; Hooper, K; Hopenhayn-Rich, C

246

Benzene pollution from gasoline usage.  

UK PubMed Central (United Kingdom)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 micrograms l-1.

Foo SC

1991-04-01

247

Benzene pollution from gasoline usage  

Energy Technology Data Exchange (ETDEWEB)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 microgramme l{sup {minus}1}. 3 figs., 14 refs., 1 tab.

Foo, S.C. (National Univ. of Singapore (Singapore))

1991-04-01

248

Benzene pollution from gasoline usage.  

Science.gov (United States)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 micrograms l-1. PMID:1857958

Foo, S C

1991-04-01

249

ITP Filtrate Benzene Removal Alternatives  

Energy Technology Data Exchange (ETDEWEB)

Existing ITP filtrate hold tanks may provide sufficient capacity and residence time to strip dissolved benzene from the incoming filtrate using nitrogen sparging in the bottom of the old tanks. This is based on equilibrium supported by late Wash test data using aged washed slurry. Theoretical considerations indicate that benzene stripping will be more difficult from the ITP unwashed high salt filtrates due to reduced mass transfer. Therefore experimental sparging data is needed to quantify the theoretical effects.Foaming limits which dictate allowable sparging rate will also have to be established. Sparging in the hold tanks will require installation of sintered metal spargers, and possibly stirrers and foam monitoring/disengagement equipment. The most critical sparging needs are at the start of the precipitation/concentration cycle, when the filtrate flux rate is the highest,and at the end of wash cycle where Henry`s equilibrium constant falls off,requiring more gas to sparge the dissolved benzene. With adequate recycle (for proper distribution) or sparging in the old tanks, the 30 inch column could be used for the complete ITP process. A courser packing would reduce back pressure while enabling benzene stripping. The Late Wash Tests indicate adequate benzene stripping even at reduced gas flow. This will require experimental verification under ITP conditions. Using the 30 in. column vs 18 in. during the wash cycle will enhance stripping without need for additional sparging provided the minimum flow requirements are met.

Dworjanyn, L.O. [Westinghouse Savannah River Company, Aiken, SC (United States)

1993-05-21

250

Unexpected change of the sense of the enantioselective hydrogenation of ethyl pyruvate catalyzed by a Pt-alumina-cinchona alkaloid system.  

Science.gov (United States)

In the enantioselective hydrogenation of ethyl pyruvate (EtPy) over beta-isocinchonine (beta-ICN) modified Pt-alumina catalysts, the major enantiomer was (R)-ethyl lactate ((R)-EtLt (ee 50%)) in toluene, while in AcOH (S)-EtLt (ee 60%) was formed; the (R) configuration is opposite to what is expected from the absolute configuration of the cinchonine backbone. PMID:12122699

Bartók, M; Sutyinszki, M; Felföldi, K; Szöllósi, Gy

2002-05-21

251

Unexpected change of the sense of the enantioselective hydrogenation of ethyl pyruvate catalyzed by a Pt-alumina-cinchona alkaloid system.  

UK PubMed Central (United Kingdom)

In the enantioselective hydrogenation of ethyl pyruvate (EtPy) over beta-isocinchonine (beta-ICN) modified Pt-alumina catalysts, the major enantiomer was (R)-ethyl lactate ((R)-EtLt (ee 50%)) in toluene, while in AcOH (S)-EtLt (ee 60%) was formed; the (R) configuration is opposite to what is expected from the absolute configuration of the cinchonine backbone.

Bartók M; Sutyinszki M; Felföldi K; Szöllósi G

2002-05-01

252

NOVEL PATHWAY OF TOLUENE CATABOLISM IN THE TRICHLOROETHYLENE DEGRADING BACTERIUM G4  

Science.gov (United States)

o-Cresol and 3-methylcatechol were identified as successive transitory intermediates of toluene catabolism by the trichloroethylene-degrading bacterium G4. he absence of a toluene dihydrodiol intermediate or toluene dioxygenase and toluene dihydrodiol dehydrogenase activities sug...

253

Study of the rearrangement of N-alkylaniline to p-aminoalkylbencene. I. N-ethyl-l-14C-aniline  

International Nuclear Information System (INIS)

The rearrangement of N-ethylaniline to p-aminoethylbenzene has been studied over the temperature range 200-300 degree centigrade using different catalysts: Cl2Co, Cl2Zn, Cl2Ni, Cl3Al, Cl2Cd and Br H.N-ethyl-1-14C-aniline has been synthesized from ethyl-1-14C-iodide and aniline and its rearrangement to p-aminoethyl-benzene proves that the ethyl group does not rearrange itself during the reaction. A scheme for the degradation of both the N-ethyl-1-14C aniline and the p-aminoethylbenzene produces is described. (Author) 14 refs.

1961-01-01

254

Nonspecific esterase activity in lymphocytes of workers occupationally exposed to benzene and its homologues  

Energy Technology Data Exchange (ETDEWEB)

Activity of nonspecific esterase (NE) was determined in peripheral blood lymphocytes from workers occupationally exposed to organic solvents containing benzene, toluene and xylene, using a semiquantitative histochemical method. The benzene, toluene and xylene concentration at the workplace of the subjects studied, was equal to 0-370,0-580 and 0-560 mg/. m/sup 3/ respectively. In subjects having a working time longer than 54 months a decreased count of lymphocytes showing presence of NE in intact lysosomes and increased count of cells with presence of this enzyme both in the partially destroyed lysosomes and in the cell cytoplasm was observed. The above phenomenon demonstrates the lysosome damage and consecutive replacing of the enzyme activity from the lysosome into the cytoplasm. Since there was a positive correlation between the exposure time and numbers of cells with damaged NE-positive lysosomes it may be suggested that the semiquantitative histochemical estimation of NE activity within the lymphocytes can be used for monitoring the toxic effect of benzene and its homologues on lymphocytes.

Moszczynski, P.; Lisiewicz, J.

1985-01-01

255

Critical influences on the rate of intramolecular vibrational redistribution: a comparative study of toluene, toluene-d3 and p-fluorotoluene.  

UK PubMed Central (United Kingdom)

The intramolecular vibrational redistribution (IVR) dynamics following the excitation of a mode in the first electronically excited states of toluene, toluene-d3 and p-fluorotoluene that has predominantly C-CH3 stretching character and an internal energy of ?1200 cm(-1) have been compared using picosecond time-resolved photoelectron imaging spectroscopy as a probe. Temporal changes in the intensities of spectral features in each molecule have enabled IVR lifetimes of 12, 15 and 50 ps, respectively, to be determined. Our measurements show that doorway states are critical in mediating the IVR dynamics in toluene and toluene-d3, and we deduce that these doorway states, which are assigned in the course of this work, are also instrumental in reducing the IVR lifetimes of these molecules relative to p-fluorotoluene.

Davies JA; Green AM; Gardner AM; Withers CD; Wright TG; Reid KL

2013-09-01

256

Inhibition of pure cultures of methanogens by benzene ring compounds  

Energy Technology Data Exchange (ETDEWEB)

The inhibition of methane production by Methanosaeta concilii GP6, Methanospirillum hungatei GP1, Methanobacterium espanolae GP9, and Methanobacterium cryantii M.o.H. during short-term (6-h) exposure to eight benzene ring compounds was studied. The concentration that caused 50% inhibition of the methane production rate (IC{sub 50}) was dependent on the species and the toxicant. Pentachlorophenol was the most toxic of the tested compounds, with an IC{sub 50} of less than 8 mg/liter for all species except M. hungatei. Abietic acid was the next most toxic compound for all the species, with an IC{sub 50} in the range of 21.4 to 203 mg/liter. Sodium benzoate was generally the least toxic, with an IC{sub 50} in the range of 1,225 to 32,400 mg/liter. 3-Chlorobenzoate was substantially more toxic (IC{sub 50}, 450 to 1,460 mg/liter) than benzoate. The inhibition by benzene, phenol, vanillic acid, and toluene was intermediate to that of pentachlorophenol and benzoate. Long-term incubation (days) studies to determine effect on growth indicated that all eight compounds were usually much more toxic than predicted from the short-term data. In these latter studies, there was generally a good correlation in the observed inhibition as determined from growth and methane production.

Patel, G.B.; Agnew, B.J.; Dicaire, C.J. (National Research Council of Canada, Ottawa, Ontario (Canada))

1991-10-01

257

Diffusion and adsorption of benzene in Regina clay  

Energy Technology Data Exchange (ETDEWEB)

Surface or near-surface spills of hydrocarbons such as gasoline and diesel often occur in clay soils which are fractured and unsaturated. For cost-effective remediation, the extent of contamination and the distribution of the various phases should be determined before the development of remediation methods. The four volatile compounds that are commonly associated with gasoline leaking from underground fuel storage tanks are benzene, toluene, ethlybenzene and xylene. Existing diffusion test methods have been used successfully for inorganic species, but the successful application of these methods to volatile organic compounds is limited. The main difficulty with experiments using volatile organics is that there is a need for careful sample handling and sensitive analytical methods to accurately measure the aqueous concentration. Work was carried out to develop an apparatus that could be used to measure the diffusion and adsorption of volatile organics in clay. The best visual fit to the experimental data for the single reservoir test was an effective diffusion coefficient of 0.01 mL/g, and an adsorption coefficient of 0.1 mL/g. Based on diffusion cell tests, there are relatively low levels of retardation for benzene as it moves in clay soils with low organic carbon content. The implications for remediation are summarized. 28 refs., 16 figs., 5 tabs.

Donahue, R.B. [Clifton Associates Ltd., Saskatoon, SK (Canada); Barbour, S.L. [Saskatchewan Univ., Dept. of Civil Engineering, Saskatoon, SK (Canada); Headley, J.V. [National Hydrology Research Inst., Saskatoon, SK, (Canada)

1999-06-01

258

Diffusion and adsorption of benzene in Regina clay  

International Nuclear Information System (INIS)

Surface or near-surface spills of hydrocarbons such as gasoline and diesel often occur in clay soils which are fractured and unsaturated. For cost-effective remediation, the extent of contamination and the distribution of the various phases should be determined before the development of remediation methods. The four volatile compounds that are commonly associated with gasoline leaking from underground fuel storage tanks are benzene, toluene, ethlybenzene and xylene. Existing diffusion test methods have been used successfully for inorganic species, but the successful application of these methods to volatile organic compounds is limited. The main difficulty with experiments using volatile organics is that there is a need for careful sample handling and sensitive analytical methods to accurately measure the aqueous concentration. Work was carried out to develop an apparatus that could be used to measure the diffusion and adsorption of volatile organics in clay. The best visual fit to the experimental data for the single reservoir test was an effective diffusion coefficient of 0.01 mL/g, and an adsorption coefficient of 0.1 mL/g. Based on diffusion cell tests, there are relatively low levels of retardation for benzene as it moves in clay soils with low organic carbon content. The implications for remediation are summarized. 28 refs., 16 figs., 5 tabs.

1999-01-01

259

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

Energy Technology Data Exchange (ETDEWEB)

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 sites in the formation of benzene. With the bifunctional Pt-Al{sub 2}O{sub 3}-Cl catalysts, an increase of the acidity is also correlated to a strong increase of the benzene formation rate, while ethylbenzene and toluene formation rates are not affected. The introduction of Sn in this previous catalyst leads from one hand, to a decrease of the global activity and, to the other hand, when Sn content is higher than 0,1 wt% to a decrease of the formation of benzene. This latter decrease could be attributed to a modification of the Broensted acid sites through the Sn atoms interacting with the support. The studies performed on model monofunctional and bifunctional catalysts allowed us to conclude that on bifunctional catalysts, toluene and ethylbenzene are formed on metallic sites by hydrogenolysis while benzene comes from the cracking of n-propylbenzene through isopropylbenzene formation on strong Broensted acid sites. From these studies new ways for reforming catalysts preparation could be considered to limit the benzene content in the reformate and particularly, the limitation as far as possible, of the chlorine content, and may be the use of more adequate tin precursor. (authors)

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

260

Phase equilibria in ionic liquid-aromatic compound mixtures, including benzene fluorination effects.  

UK PubMed Central (United Kingdom)

This work extends the scope of previous studies on the phase behavior of mixtures of ionic liquids with benzenes or its derivatives by determining the solid-liquid and liquid-liquid phase diagrams of mixtures containing an ionic liquid and a fluorinated benzene. The systems studied include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide plus hexafluorobenzene or 1,3,5-trifluorobenzene and 1-ethyl-3-methylimidazolium triflate or N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide plus benzene. The phase diagrams exhibit different kinds of solid-liquid behavior: the (usual) occurrence of eutectic points; the (not-so-usual) presence of congruent melting points and the corresponding formation of inclusion crystals; or the observation of different ionic liquid crystalline phases (polymorphism). These different types of behavior can be controlled by temperature annealing during crystallization or by the nature of the aromatic compound and can be interpreted, at a molecular level, taking into account the structure of the crystals or liquid mixtures, together with the unique characteristics of ionic liquids, namely the dual nature of their interactions with aromatic compounds.

Blesic M; Lopes JN; Pádua AA; Shimizu K; Gomes MF; Rebelo LP

2009-05-01

 
 
 
 
261

FIELD COMPARISON OF TWO KINDS OF CHARCOAL TUBES FOR SAMPLING AROMATIC HYDROCARBONS (TOLUENE & XYLENE) IN A PAINT FACTORY  

Directory of Open Access Journals (Sweden)

Full Text Available In order to evaluate the effectiveness of the Iranian made charcoal tubes in the field , 60 local made and 60 imported ones (SKC type) were randomly selected and placed side by side for sampling aromatic hydrocarbons (including Benzene, Toluene, Xylene) in workers breathing zone in a paint factory. The results indicated that there were no statistically significant differences between the mean concentrations of aromatic hydrocarbons measured in studied groups. The ratios of pressure drop to flow rate of Iranian made tubes were statistically higher than the SKC ones (P<0.0l).

P .Nassiri; F. Golbabai; A. Barzegar

1996-01-01

262

Modelling and Simulation Of Benzene Alkylation Process Reactors For Production Of Ethylbenzene  

Directory of Open Access Journals (Sweden)

Full Text Available The goal of this paper is to develop a simulation software for the ethyl benzene production unit in aPetrochemical Complex of Iran. Ethyl benzene whose consumption has rapidly increased in recent years, isthe feed for production of styrene monomer. This material is produced from alkylation of benzene withethylene. A process simulator can play a very important role in the development of this process. In thisresearch, alkylation of benzene for production of ethylbenzene has been simulated. First the mass, energyand momentum balance equations have been developed for the axial flow reactor. Optimization techniqueshave then been applied to modify the kinetic equations presented in literature to somehow satisfy the unitconditions. Finally the model predicted values such as pressure, reactor temperature, reactant conversionand products compositions have been compared with those of experimental ones adopted from theindustrial unit. The comparison reveals that the model predicted values are adequately in compliance withthe experimental data and hence can be used, with sufficient accuracy, to design pilot plants and other newunits.

Hamid Ganji; Jafar S. Ahari; Amir Farshi; Majid Kakavand

2004-01-01

263

The Solubility of Phenylborate Compounds in Benzene  

Energy Technology Data Exchange (ETDEWEB)

The original goal of this scoping study was to determine if the solubility of sodium and potassium tetraphenylborates in benzene was sufficiently large to justify designing and performing kinetic studies on a benzene-phase catalytic reaction.

Eibling, R.E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1998-04-01

264

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...of this section: DANGER BENZENE CANCER HAZARD FLAMMABLEâNO SMOKING AUTHORIZED...warning: DANGER CONTAINS BENZENE CANCER HAZARD (3) Information and training...usually available, emerging diagnostic technology and innovative regimes make...

2013-07-01

265

The Solubility of Phenylborate Compounds in Benzene  

International Nuclear Information System (INIS)

The original goal of this scoping study was to determine if the solubility of sodium and potassium tetraphenylborates in benzene was sufficiently large to justify designing and performing kinetic studies on a benzene-phase catalytic reaction.

1998-01-01

266

Occupational exposure to benzene in China.  

UK PubMed Central (United Kingdom)

Of a total of 528,729 workers exposed to benzene or benzene mixtures in China, 508,818 (96.23%) were examined. Altogether 2,676 cases of benzene poisoning were found, a prevalence of 0.15%. A higher prevalence of benzene poisoning was found in the cities of Hangjou, Hefei, Nanjing, Shenyang, and Xian. The geometric mean concentration of benzene in 50,255 workplaces was 18.1 mg/m3 but 64.6% of the workplaces had less than 40 mg/m3. There was a positive correlation between the prevalence of benzene poisoning and the concentration in shoemaking factories. The prevalence of benzene induced aplastic anaemia in shoemakers was about 5.8 times that occurring in the general population. The results of this investigation show the need for a practicable hygiene standard to prevent benzene poisoning.

Yin SN; Li Q; Liu Y; Tian F; Du C; Jin C

1987-03-01

267

ASSESSMENT OF HUMAN EXPOSURE TO TOLUENE DIISOCYANATE  

Directory of Open Access Journals (Sweden)

Full Text Available Assessment of human exposure to toluene diisocyanate. Toluene diisocyanate (TDI), an aromatic compound, may be dangerous for human health. Diisocyanates have wide industrial use in the fabrication of flexible and rigid foams, fibers, elastomers, and coatings such as paints and varnishes. Isocyanates are known skin and respiratory sensitizers, and proper engineering controls should be in place to prevent exposure to isocyanate liquid and vapor; exposure to TDI vapors is well documented to increase asthma risk. The study focused on the exposure of workers and nearby populations to toluene diisocyanate in a Polyurethane Foam Factory located in Baia Mare, Romania. Workplace air measurements were performed in different departments of the plant, after sampling either in fixed points or as personal monitoring. Sampling in four different locations of Baia Mare town was carried out, - during and after the foaming process. TDI sampling was performed on silica cartridge followed by GC-MS analysis. TDI concentration at workplace was lower than 0,035 mg/m³, which represents the permissible exposure limit, while in the city the TDI concentration had shown values below 0,20 ?g/m³. Health assessment of a group of 49 workers was based on questionnaire interview, determination of TDI antibodies and lung function tests. Data collected until this stage do not show any negative effects of TDI on the employees health. Since this plant had only recently begun operating, continuous workplace and ambient air TDI monitoring, along with workers health surveillance, is deemed necessary.

OLIVIA ANCA RUSU; CRISTINA NEAGU; IRINA DUMITRASCU; IULIA NEAMTIU; ALEXANDRU ZEIC; EUGEN GURZAU

2011-01-01

268

77 FR 23625 - Quizalofop Ethyl; Pesticide Tolerances  

Science.gov (United States)

...EPA-HQ-OPP-2010-1018; FRL-9340-5] Quizalofop Ethyl; Pesticide Tolerances AGENCY...establishes tolerances for residues of quizalofop ethyl in or on multiple commodities...tolerances for residues of the herbicide quizalofop ethyl,...

2012-04-20

269

N-[(3-Ethyl-phen-yl)carbamo-thio-yl]-2,2-di-phenyl-acetamide.  

UK PubMed Central (United Kingdom)

In the title mol-ecule, C23H22N2OS, the di-phenyl-acetyl and ethyl-benzene groups adopt a trans-cis conformation, respectively, with respect to the S atom across the (S=)C-N bonds. This conformation is stabilized by an intra-molecular N-H?O hydrogen bond and a weak C-H?S hydrogen bond. The ethyl-substituted benzene ring forms dihedral angles of 87.53?(15) and 73.94?(15)° with the phenyl rings. In the crystal, N-H?O hydrogen bonds link mol-ecules into chains along [100]. A weak C-H?? inter-action is also observed.

Yusof MS; Razali NR; Arshad S; Rahman AA; Razak IA

2013-01-01

270

Impact of nitrate dose on toluene degradation under denitrifying condition.  

UK PubMed Central (United Kingdom)

In this study, we investigated the impact of nitrate dose on toluene degradation by Pseudomonas putida to elucidate the upper limit of nitrate concentration and whether an optimum ratio of nitrate to toluene concentration exists. Batch microcosm studies were conducted in order to monitor toluene degradation for various ratios (2-20) of nitrate to toluene with nitrate concentrations ranging from 0 to 700 mg?L(-1) for a given toluene concentration of 50 and 25 mg?L(-1) during 4-day (short term) and 14-day (long term) incubation time, respectively. The short-term study revealed that nitrate concentration of 500 mg?L(-1) was toxic to bacteria and the optimum concentration was 300 mg?L(-1) yielding the highest toluene degradation rate (0.083 mg?L(-1)?h(-1)). In the batch study of long term, toluene degradation was limited to 6 days after which the nitrate at 50 mg?L(-1) was depleted, indicating that nitrate was a necessary electron acceptor. For both batch studies, an optimum ratio of 6 was found yielding the highest toluene degradation rate. This indicates that an appropriate nitrate dose is essential for efficient degradation of toluene when bioremediation of groundwater contaminated with toluene is under consideration.

Kim DJ; Park MR; Lim DS; Choi JW

2013-05-01

271

Composition of extracts produced by brown coal treatment with toluene under supercritical conditions  

Energy Technology Data Exchange (ETDEWEB)

Brown coal from the Sieniawa mine in Poland was extracted using toluene at 613 K, and 9 MPa in an OL 105 reactor. Chemical composition of coal extracts is shown in 3 tables. Coal extract analysis was based on differential extract solvolysis in benzene and hexane, fractionation by means of adsorption liquid chromatography, ion exchange chromatography as well as identification of functional groups and compounds using infrared spectrometry or gas chromatography. The coal extract consisted of 90% of compounds with molecular weight below 600 (of these, more than 40% were hydrocarbons), and 10% of various oxygen compounds. N-alkanes, triterpenes, aromatic hydrocarbons and hydroaromatic hydrocarbons with alkyl side chains predominated in the hydrocarbons. Simple and complex phenols or their homologues predominated in the oxygen compounds. 13 references.

Bodzek, D.; Bularz, K.; Szkuta-Pochopien, T.

1984-11-01

272

(Z)-Methyl 2-[(2-eth-oxy-6-formyl-phen-oxy)meth-yl]-3-(4-ethyl-phen-yl)acrylate.  

Science.gov (United States)

The title compound, C(22)H(24)O(5), consists of two substituted benzene rings linked by an ethyl acrylate group. The dihedral angle between the two benzene rings is 58.39?(7)°. The crystal packing is governed by two C-H?O inter-actions, one of which forms centrosymmetric dimers with a graph-set descriptor of R(2) (2)(18). PMID:22199755

Gangadharan, Rajeswari; Sethusankar, K; Selvakumar, Raman; Bakthadoss, Manickam

2011-11-09

273

Cloning of the genes for and characterization of the early stages of toluene and o-xylene catabolism in Pseudomonas stutzeri OX1.  

UK PubMed Central (United Kingdom)

In order to study the toluene and o-xylene catabolic genes of Pseudomonas stutzeri OX1, a genomic library was constructed. A 28-kb EcoRI restriction endonuclease DNA fragment, cloned into the vector plasmid pLAFR1 and designated pFB3401, permitted Pseudomonas putida PaW340 to convert toluene and o-xylene into the corresponding meta-ring fission products. Physical and functional endonuclease restriction maps have been derived from the cloned DNA fragment. Further subcloning into and deletion analysis in the Escherichia coli vector pGEM-3Z allowed the genes for the conversion of toluene or o-xylene into the corresponding catechols to be mapped within a 6-kb region of the pFB3401 insert and their direction of transcription to be determined. Following exposure to toluene, E. coli cells carrying this 6-kb region produce a mixture of o-cresol, m-cresol, and p-cresol, which are further converted to 3-methylcatechol and 4-methylcatechol. Similarly, a mixture of 2,3-dimethylphenol and 3,4-dimethylphenol, further converted into dimethylcatechols, was detected after exposure to o-xylene. The enzyme involved in the first step of toluene and o-xylene degradation exhibited a broad substrate specificity, being able to oxidize also benzene, ethylbenzene, m-xylene, p-xylene, styrene, and naphthalene. Deletions of the 6-kb region which affect the ability to convert toluene or o-xylene into the corresponding methylphenols compromise also their further oxidation to methylcatechols. This suggests that a single enzyme system could be involved in both steps of the early stages of toluene and o-xylene catabolism.

Bertoni G; Bolognese F; Galli E; Barbieri P

1996-10-01

274

Ethyl`s MMT ready to hit the road  

Energy Technology Data Exchange (ETDEWEB)

After spending two decades and about $30 million on the fight to sell the fuel octane booster methylcyclopentadienyl manganese tricarbonyl (MMT), Ethyl has started marketing the product. Ethyl president and chief operating officer Thomas Gottwald says he expects a profit from MMT from the outset. {open_quotes}MMT is a gangbuster new product,{close_quotes} says Paul Raman, an analyst with S.G. Warburg (New York), {open_quotes}and it will be very profitable for Ethyl.{close_quotes} Ethyl`s effort to bring MMT to market faced pressure from EPA and automakers. EPA says MMT should not be marketed until more research is done on health effects of the manganese-based additive. US automakers oppose MMT, fearing it will damage catalytic converters. Last October Ethyl won a federal appeals court decision compelling EPA to approve MMT use. Gottwald says the MMT fight has been well worth it: {open_quotes}We fought with our eye on the bottom line.{close_quotes}

Stringer, J.

1996-01-03

275

EPA dashes ethyl`s hopes for MMT  

Energy Technology Data Exchange (ETDEWEB)

Up until the Environmental Protection Agency (EPA; Washington) decided to deny Ethyl`s (Richmond, VA) petition to sell manganese-based gasoline additive MMT, many on Wall Street were bullish. Bets were that MMT sales could create an up to $200 million/year sales windfall for Ethyl with $60 million/year income, and push its near $26/share price up by at least 50 cts. But EPA ruled January 8 against MMT in unleaded gas due to its potential to increase hydrocarbon emissions. What kept analysts hoping is that octane enhancer MMT`s environmental impacts are mixed. An Ethyl spokesman says that MMT cut tailpipe emissions of nitrogen oxide by 20% and carbon monoxide by 7%. Ethyl also points out that MMT could save as much as 85,000 barrels/day of imported oil because of lower energy requirements in blending. And the product has sold for 13 years in Canada with no reported ill health effects. But, points out Smith, Barney (New York) analyst James Wilbur, Canada is not the congested Los Angeles basin, where the unknown effects of small amounts of heavy metal manganese would show up a lot faster if every car burnt MMT. For now, the financial effect of the decision is negligible, although at some point Ethyl may have to take a write-down on its Orangeburg, NC plant.

Heller, K.

1992-01-15

276

Ultraselective and sensitive detection of xylene and toluene for monitoring indoor air pollution using Cr-doped NiO hierarchical nanostructures  

Science.gov (United States)

Ultraselective and sensitive detection of xylene and toluene with minimum interferences of other indoor air pollutants such as benzene, ethanol, and formaldehyde is achieved using NiO hierarchical nanostructures doped with Cr. Pure and 1.15-2.56 at% Cr-doped NiO flower-like hierarchical nanostructures assembled from nanosheets are prepared by a simple solvothermal reaction and their gas sensing characteristics toward o-xylene and toluene gases are investigated. The 1.15 at% Cr-doped NiO hierarchical nanostructures show high responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 11.61 and 7.81, respectively) and negligible cross-responses to 5 ppm of benzene, formaldehyde, ethanol, hydrogen, and carbon monoxide. However, pure NiO nanostructures show low responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 2.01 and 1.14, respectively) and no selectivity toward any specific gas is observed. Significant enhancement of the response and selectivity to o-xylene and toluene is attributed to the decrease in the hole concentration in NiO and the catalytic oxidation of methyl groups by Cr doping.Ultraselective and sensitive detection of xylene and toluene with minimum interferences of other indoor air pollutants such as benzene, ethanol, and formaldehyde is achieved using NiO hierarchical nanostructures doped with Cr. Pure and 1.15-2.56 at% Cr-doped NiO flower-like hierarchical nanostructures assembled from nanosheets are prepared by a simple solvothermal reaction and their gas sensing characteristics toward o-xylene and toluene gases are investigated. The 1.15 at% Cr-doped NiO hierarchical nanostructures show high responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 11.61 and 7.81, respectively) and negligible cross-responses to 5 ppm of benzene, formaldehyde, ethanol, hydrogen, and carbon monoxide. However, pure NiO nanostructures show low responses to 5 ppm of o-xylene and toluene (ratio of resistance to gas and air = 2.01 and 1.14, respectively) and no selectivity toward any specific gas is observed. Significant enhancement of the response and selectivity to o-xylene and toluene is attributed to the decrease in the hole concentration in NiO and the catalytic oxidation of methyl groups by Cr doping. Electronic supplementary information (ESI) available: X-ray diffraction patterns and SEM images of pure and Cr-doped Ni precursors; XPS spectra, pore size distribution, gas response, sensor resistance in air, gas selectivity of pure and Cr-doped NiO hierarchical nanostructures. See DOI: 10.1039/c3nr01281f

Kim, Hyo-Joong; Yoon, Ji-Wook; Choi, Kwon-Il; Jang, Ho Won; Umar, Ahmad; Lee, Jong-Heun

2013-07-01

277

(E)-Ethyl N?-[1-(2-hydroxyphenyl)ethylidene]hydrazinecarboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available In the molecule of the title compound, C11H14N2O3, the dihedral angle between the benzene ring and the hydrazinecarboxylate mean plane is 3.65?(12)°. Intramolecular C—H...N and O—H...N hydrogen bonds result in the formation of a nearly planar six-membered ring, which is oriented at a dihedral angle of 2.38?(3)° with respect to the benzene ring, and a five-membered ring having an envelope conformation. In the crystal structure, intermolecular N—H...O and C—H...N hydrogen bonds link the molecules. There is a C—H...? contact between the benzene ring and the methyl group of the ethyl substituent.

Bo Gao

2008-01-01

278

Solubility of water in MEK-toluene  

Energy Technology Data Exchange (ETDEWEB)

The authors studied the solubility of H/sub 2/O in MEK-toluene mixture (60:40, vol.%), used as a solvent during oil dewaxing and paraffin deoiling. The study was carried out visually by the polythermal method at a temperature of +56 to-42 degrees. MEK was preliminarily dehydrated by zeolite and H/sub 2/O-content in the dehydrated solvent was controlled by a special method. The dependencies describing the solubility of H/sub 2/O in the mixture under study are presented.

Roschin, Yu.N.; Vazhnova, G.P.

1981-01-01

279

l-Histidinium p-toluene-sulfonate.  

Science.gov (United States)

In the title salt, C6H10N3O2 (+)·C7H7O3S(-), the imidazole ring makes a dihedral angle of 70.93?(12)° with the plane of the toluene ring. In the crystal, the ions are linked via N-H?O and weak C-H?O hydrogen bonds forming two-dimensional networks lying parallel to (001). These networks are linked via C-H?? inter-actions, forming a three-dimensional structure. PMID:23723944

Muralidharan, Srinivasan; Nagapandiselvi, Perumal; Srinivasan, Thothadri; Gopalakrishnan, Rengasamy; Velmurugan, Devadasan

2013-04-30

280

l-Histidinium p-toluene-sulfonate.  

UK PubMed Central (United Kingdom)

In the title salt, C6H10N3O2 (+)·C7H7O3S(-), the imidazole ring makes a dihedral angle of 70.93?(12)° with the plane of the toluene ring. In the crystal, the ions are linked via N-H?O and weak C-H?O hydrogen bonds forming two-dimensional networks lying parallel to (001). These networks are linked via C-H?? inter-actions, forming a three-dimensional structure.

Muralidharan S; Nagapandiselvi P; Srinivasan T; Gopalakrishnan R; Velmurugan D

2013-05-01

 
 
 
 
281

Substrate- and nutrient-limited toluene biotransformation in sandy soil  

Energy Technology Data Exchange (ETDEWEB)

Lab microcosm tests of the rate of toluene biodegradation were performed using soil from the A, B, and C horizons of the unsaturated zone of a sandy field site. Toluene biodegradation was rapid, occurring at a time scale comparable to the rate of sorption in many of the microcosms and demonstrating the potential for bioremediation of these contaminants in unsaturated soil. In the A horizon, with an initial toluene concentration in the solution phase of 4.5 mg/L, degradation was controlled by substrate-limited growth on toluene as the primary substrate. Soil from the B and C horizons initially showed similar behavior with a lower toluene concentrations of about 2.5 mg/L. The maximum utilization rate ([mu][sub max]) for soil from all three depths was 2.0 d[sup [minus]1]. With repeated exposure to moderate to high concentrations of toluene, transformation in the B- and C-horizon soil appeared to be zero order, at a rate of 1.0 to 2.0 [mu]g toluene/g soil/d. In C-horizon soil that had been taken directly from the field, the transformation rate was almost immeasurably slow. Addition of nitrogens as either ammonium or nitrate accelerated the degradation, showing that nitrogen was the most limiting nutrient. The apparent adaptation period observed before rapid toluene removal was fit by a substrate-limited growth model. Greater numbers of toluene-degrading microorganisms were found in soil exposed to toluene than in unexposed soil, supporting biomass growth as the explanation for the adaptation period. The results of enumeration of heterotrophs compared to the numbers of toluene degraders suggested that a small proportion to the total viable microorganisms were responsible for degradation of toluene.

Allen-King, R.M. (Washington State Univ., Pullman, WA (United States). Dept. of Geology); Barker, J.F.; Gillham, R.W. (Univ. of Waterloo, Ontario (Canada). Waterloo Centre for Groundwater Research); Jensen, B.K. (Water Quality Inst., Horsholm (Denmark). Environmental Biotechnology Section)

1994-05-01

282

Bioremediation of chlorinated benzene compounds  

Energy Technology Data Exchange (ETDEWEB)

In early 1994, investigations at a pharmaceutical manufacturing site revealed extensive areas of soil contaminated with chlorinated benzenes. The soil was a heavy clay and contained chlorobenzene (CB), 1,2-dichlorobenzene (referred to in this paper as DCB), and small amounts of 1,3- and 1,4-dichlorobenzene and other solvents. The soil was bioremediated in a pilot-scale treatment using an ex situ process with various inorganic and organic amendments. Approximately 90% of the DCB mass present in the soil was removed over a period of 2 to 3 weeks. Up to 100-fold increases in both total heterotrophs and specific degraders were observed. Residual concentrations of chlorinated benzenes were generally below detection limits. Adding organic matter did not appear to significantly enhance the treatment efficiency. Mass balance calculations applied to the treatment indicated that less than 5% of the chlorinated benzenes were removed by volatilization. Evidence was obtained that approximately 90% of the DCB was removed by biodegradation in these pilot-scale trials. Laboratory shake flask trials were conducted which confirmed that the soils in the pilot-scale treatment contained microorganisms capable of mineralizing CB and DCB.

Peck, P.C.; Rhodes, S.H. [Minenco Bioremediation Services, N. Sydney, New South Wales (Australia); Guerin, T.F. [Minenco Bioremediation Services, Bundoora, Victoria (Australia)

1995-12-31

283

Ethyl fuel from nonpetroleum sources  

Energy Technology Data Exchange (ETDEWEB)

It has been shown that ethanol-ester mixtures - Ethyl Fuel - can be prepared from nonpetroleum sources such as coal, oil shale, etc. Production consists of the following steps: gasification of basic feedstock, synthesis of methanol and carbonylation of methanol to Ethyl Fuel. Depending on the final composition, preparation from methanol can be carried out with 92 + % selectivity. Based on our studies, Ethyl Fuel produced from methanol could be significantly cheaper than anhydrous ethanol produced via fermentation of starch or cellulose feedstocks. Evaluation of the 5, 10 and 15 vol % mixtures of Ethyl Fuel with commercial unleaded gasoline showed that it can be mixed with conventional gasoline to give a blend having essentially the same properties as those observed for blends of 100% anhydrous ethanol and gasoline. Evaluation of the Ethyl Fuel/gasoline blends did not show added corrosion problems over those shown for 100% anhydrous ethanol-gasoline blends. Octane numbers and blending octane rating were only slightly lower than for the fuels made of a 100% anhydrous ethanol and gasoline. The water tolerance and phase separation of Ethyl Fuel blends were essentially identical to that of blends from pure ethanol.

Beuther, H.; Kobylinski, T.P.; Singerman, G.M.; Pretzer, W.R.

1980-02-01

284

Chemical Kinetic Characterization of Combustion Toluene  

Energy Technology Data Exchange (ETDEWEB)

A study is performed to elucidate the chemical kinetic mechanism of combustion of toluene. A detailed chemical kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Critical conditions of extinction and ignition were measured in strained laminar flows under nonpremixed conditions in the counterflow configuration. Numerical calculations are performed using the chemical kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and ignition are predicted and compared with the experimental data. For both premixed and nonpremixed systems, sensitivity analysis was used to identify the reaction rate constants that control the overall rate of oxidation in each of the systems considered.

Pitz, W J; Seiser, R; Bozzelli, J W; Da Costa, I; Fournet, R; Billaud, F; Battin-Leclerc, F; Seshadri, K; Westbrook, C K

2001-03-20

285

ESTUDIO DEL EQUILIBRIO LÍQUIDO-LÍQUIDO DE BENCENO + (HEXANO, HEPTANO Y CICLOHEXANO) CON EL LÍQUIDO IÓNICO 1-ETIL-3-METILIMIDAZOLIO ETILSULFATO A 308,15 K/ STUDY 0F LIQUID-LIQUID EQUILIBRIIM 0F BENZENE + (HEXAXE, HEPTME A\\D CYCLOHEXAXE) WITH THE IOMC LIQUID 1-ETHYL-3-METHYLIMIDAZ0LIIM ETHYLSULFATE AT 308.15 K/ ESTUDO DO EQUILÍBRIO LÍQUIDO-LÍQUIDO DE BENZENO + (HEXANO, HEPTANO E CICLO-HEXANO) COM O LÍQUIDO IÔNICO 1-ETIL-3-METILIMIDAZOLIO ETILSULFATO A 308,15 K  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O equilíbrio líquido-líquido (ELL) de los sistemas ternários benzeno + (hexa-no, heptano e ciclo-hexano) com o líquido iônico 1-etil-3-metilimidazólio etilsulfato (EMIM-EtS0(4)) com 308,15 K, seletividade (S) e o coeficiente de distribuição (?) são calculados a partir dos dados experimentais. Ela determina a capacidade de líquido iônico como solvente para a separação de aromático a partir de suas misturas com hidrocar-bonetos alifáticos. A região de (more) imiscibilidade aumentou na seguinte ordem: ciclo-hexano Abstract in spanish Se determinó el equilibrio líquido-líquido (ELL) de los sistemas ternarios benceno + (hexano, heptano y ciclohexano) con el líquido iónico 1-etil-3-metilimidazolio etilsulfato (EMIM-EtSO4) a 308,15 K; la selectividad (S) y el coeficiente de distribución (?) se calcularon desde los datos experimentales que se utilizaron para determinar la capacidad del líquido iónico como solvente para la separación del aromático desde sus mezclas con hidrocarburos alifátic (more) os. La región de inmiscibilidad aumentó en el siguiente orden: ciclohexano Abstract in english The equilibrium liquid-liquid (ELL) of ternary systems benzene + (hexane, heptane and cyclohexane) with the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMIM-EtS0(4)) at 308.15 K, selectivity (S) and the distribution coefficient (?) are calculated from experimental data. The ability of ionic liquid as solvent for separation of the aromatic from their mixtures with ali-phatic hydrocarbons is analyzed. The region of immiscibility increased in the following or (more) der: cyclohexane

Martínez Reina, Marlon; Amado González, Eliseo; Muñoz Muñoz, Yonny Mauricio

2012-01-01

286

Mixed Aggregates of an Alkyl Lithium Reagent and a Chiral Lithium Amide Derived from N-Ethyl-O-Triisopropylsilyl Valinol.  

UK PubMed Central (United Kingdom)

The crystal structure of a mixed aggregate containing lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine derived from (S)-valinol and cyclopentyllithium is determined by X-ray diffraction. The mixed aggregate adopts a ladder structure in solid state. The ladder-type mixed aggregate is also the major species in a toluene-d8 solution containing approximately 1:1 mole ratio of the lithiated chiral amide to cyclopentyllithium. A variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula (D-FW) weight correlation analyses and other one- and two-dimensional NMR techniques allowed us to characterize the complex in solution. Solution state structures of the mixed aggregates of n-butyl, sec-butyllithium, isopropyllithium with lithiated (S)-N-ethyl-3-methyl-1-(triisopropylsilyloxy)butan-2-amine are also reported. Identical dimeric, ladder-type, mixed aggregates are the major species at a stoichiometric ratio of 1:1 lithium chiral amide to alkyllithium in toluene-d8 solution for all of the different alkyllithium reagents.

Su C; Hopson R; Williard PG

2013-08-01

287

Is toluene diamine a sensitizer and is there cross-reactivity between toluene diamine and toluene diisocyanate?  

UK PubMed Central (United Kingdom)

Toluene diamine (TDA) is formed when toluene diisocyanate (TDI), a potent sensitizer, comes in contact with an aqueous environment. The sensitizing capacity of TDA and the cross-reactivity between TDI and TDA are unknown. TDA (5-25%) and TDI (0.3%), dissolved in acetone/olive oil (AOO) (4:1) were tested in the mouse local lymph node assay (LLNA). To determine the capacity of TDA to elicit an asthmatic response and to determine the cross-reaction with TDI, a locally developed experimental mouse model of chemical-induced asthma was used. On days 1 and 8, BALB/c mice received 20 microl of TDI (0.3%), TDA (20%), or AOO (4:1) on each ear. On day 15, they received an intranasal instillation of TDI (0.1%), TDA (0.5%) or AOO (3:2). The EC(3) of TDA in the LLNA is 19%. In the model of chemical-induced asthma, TDI induced a ventilatory response [increased Penh after challenge; increased airway hyperreactivity (AHR)], inflammatory changes (bronchoalveolar lavage neutrophils), and immunological changes (increased CD19(+) lymphocytes, IL-4 and total serum IgE), whereas TDA did not show any of these responses. Mice sensitized with TDI and challenged with TDA also did not show any airway or inflammatory response, although they had increased levels of total serum IgE. Mice sensitized with TDA and challenged with TDI did not show any response. According to the classification of sensitizers in the LLNA, TDA is a weak dermal sensitizer. In the experimental mouse model of chemical-induced asthma, TDA does not act as a respiratory sensitizer, at the concentration used. No cross-reactivity between TDI and TDA was found.

Vanoirbeek JA; De Vooght V; Synhaeve N; Nemery B; Hoet PH

2009-06-01

288

Is toluene diamine a sensitizer and is there cross-reactivity between toluene diamine and toluene diisocyanate?  

Science.gov (United States)

Toluene diamine (TDA) is formed when toluene diisocyanate (TDI), a potent sensitizer, comes in contact with an aqueous environment. The sensitizing capacity of TDA and the cross-reactivity between TDI and TDA are unknown. TDA (5-25%) and TDI (0.3%), dissolved in acetone/olive oil (AOO) (4:1) were tested in the mouse local lymph node assay (LLNA). To determine the capacity of TDA to elicit an asthmatic response and to determine the cross-reaction with TDI, a locally developed experimental mouse model of chemical-induced asthma was used. On days 1 and 8, BALB/c mice received 20 microl of TDI (0.3%), TDA (20%), or AOO (4:1) on each ear. On day 15, they received an intranasal instillation of TDI (0.1%), TDA (0.5%) or AOO (3:2). The EC(3) of TDA in the LLNA is 19%. In the model of chemical-induced asthma, TDI induced a ventilatory response [increased Penh after challenge; increased airway hyperreactivity (AHR)], inflammatory changes (bronchoalveolar lavage neutrophils), and immunological changes (increased CD19(+) lymphocytes, IL-4 and total serum IgE), whereas TDA did not show any of these responses. Mice sensitized with TDI and challenged with TDA also did not show any airway or inflammatory response, although they had increased levels of total serum IgE. Mice sensitized with TDA and challenged with TDI did not show any response. According to the classification of sensitizers in the LLNA, TDA is a weak dermal sensitizer. In the experimental mouse model of chemical-induced asthma, TDA does not act as a respiratory sensitizer, at the concentration used. No cross-reactivity between TDI and TDA was found. PMID:19332649

Vanoirbeek, Jeroen A J; De Vooght, Vanessa; Synhaeve, Nicholas; Nemery, Benoit; Hoet, Peter H M

2009-03-30

289

Toxicological profile for benzene. Final report  

Energy Technology Data Exchange (ETDEWEB)

The Statement was prepared to give information about benzene and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,300 hazardous waste sites as the most serious in the nation. Benzene has been found in at least 743 of these sites. However, one does not know how many of the 1,300 NPL sites have been evaluated for benzene. As EPA evaluates more sites, the number of sites at which benzene is found may change. The information is important to know because benzene may cause harmful health effects and because these sites are potential or actual sources of human exposure to benzene.

Jewell, C.S.E.; Hibbs, B.F.; Brankovan, V.; Anderson, E.

1993-04-01

290

Thermal study of metalloporphyrin complexes with benzene  

International Nuclear Information System (INIS)

Crystallosolvates of MP (P - dianions of tetra(3,5-di-tret-butylphenyl)porphyrin, M - Co, Ni, Cu, Zn, Cd, Hg) complexes with benzene are obtained by isothermal evaporation of the solutions at 35 Deg C. The processes of their thermal decomposition are investigated. Composition, temperature and enthalpy of benzene evaporation from the crystallosolvates are determined. It is detected that ?-system of of macrocycle of metalloporphyrinates appears as ?-donor to aromatic system of benzene molecule

2005-01-01

291

Anaerobic degradation of toluene by pure cultures of denitrifying bacteria.  

UK PubMed Central (United Kingdom)

Several denitrifying Pseudomonas spp., isolated with various aromatic compounds, were tested for the ability to degrade toluene in the absence of molecular oxygen. Four out of seven strains were able to degrade toluene in the presence of N2O. More than 50% of the 14C from ring-labelled toluene was released as CO2, and up to 37% was assimilated into cell material. Furthermore it was demonstrated for two strains that they were able to grow on toluene as the sole carbon and energy source in the presence of N2O. Suspensions of cells pregrown on toluene degraded toluene, benzaldehyde or benzoate without a lag phase and without accumulation of intermediates. p-Cresol, p-hydroxybenzylalcohol, p-hydroxybenzaldehyde or p-hydroxybenzoate was degraded much slower or only after distinct lag times. In the presence of fluoroacetate [14C]toluene was transformed to [14C]benzoate, which suggests that anaerobic toluene degradation proceeds through oxidation of the methyl side chain to benzoate.

Schocher RJ; Seyfried B; Vazquez F; Zeyer J

1991-01-01

292

Health Assessment of Toluene in California Drinking Water,  

Science.gov (United States)

The report is a review of the existing literature pertinent to the health risk posed by the use of toluene-contaminated drinking water. Also included in the study is an estimate of the toluene exposure of California residents based on the most recent data...

N. Reed W. Reed L. Beltran R. Li I. Encomienda

1989-01-01

293

Health Risk Assessment and Applied Action Level of Toluene.  

Science.gov (United States)

The purpose of the document is to provide information on the toxicity of toluene and to estimate Applied Action Levels (AALs) for toluene in water, air, and soil. The information provided will aid the California Dept. of Health Services manage hazardous w...

N. R. Reed W. A. Reed K. Weir I. Encomienda L. M. Beltran

1989-01-01

294

Production of Phenol from Benzene via Cumene  

Science.gov (United States)

|Describes an undergraduate chemistry laboratory experiment involving the production of phenol from benzene with the intermediate production of isopropylbenzene and isopropylbenzene hydroperoxide. (SL)|

Daniels, D. J.; And Others

1976-01-01

295

4-Methyl-N-[(E)-4-methyl-1-(4-methyl­phenyl­sulfon­yl)-1,2-dihydropyridin-2-yl­idene]benzene­sulfonamide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The reaction of 2-(amino­meth­yl)pyridine and 4-toluene­sulfonyl chloride in CH2Cl2 at pH 8 led to the title compound, C20H20N2O4S2. The aromatic rings are almost perpendicular to each other and the dihedral angles between the aromatic ring planes are 74.33?(9) (central pyridine versus benzene ring ...

Tabatabaee, Masoumeh; Ghassemzadeh, Mitra; Hesami, Liela; Neumüller, Bernhard

296

MEASUREMENT OF BENZENE OXIDE IN THE BLOOD OF RATS FOLLOWING ADMINISTRATION OF BENZENE  

Science.gov (United States)

Although it is generally assumed that metabolism of benzene proceeds through an initial step involving oxidation to benzene oxide (BO) by CYP450 in the liver, the production of BO has never been unambiguously confirmed in animals dosed with benzene. Furthermore, prevailing hypo...

297

Biodegradation of benzene homologues in contaminated sediment of the East China Sea.  

Science.gov (United States)

This study focused on acclimating a microbial enrichment to biodegrade benzene, toluene, ethylbenzene and xylenes (BTEX) in a wide range of salinity. The enrichment degraded 120 mg/L toluene within 5d in the presence of 2M NaCl or 150 mg/L toluene within 7d in the presence of 1-1.5M NaCl. PCR-DGGE (polymerase chain reaction-denatured gradient gel electrophoresis) profiles demonstrated the dominant species in the enrichments distributed between five main phyla: Gammaproteobacteria, Sphingobacteriia, Prolixibacter, Flavobacteriia and Firmicutes. The Marinobacter, Prolixibacter, Balneola, Zunongwangia, Halobacillus were the dominant genus. PCR detection of genotypes involved in bacterial BETX degradation revealed that the degradation pathways contained all the known initial oxidative attack of BTEX by monooxygenase and dioxygenase. And the subsequent ring fission was catalysed by catechol 1,2-dioxygenase and catechol 2,3-dioxygenase. Nuclear magnetic resonance (NMR) spectroscopy profiles showed that the bacterial consortium adjusted the osmotic pressure by ectoine and hydroxyectoine as compatible solutes to acclimate the different salinity conditions. PMID:22989641

Li, Hui; Zhang, Qian; Wang, Xiao-Li; Ma, Xing-Yuan; Lin, Kuang-Fei; Liu, Yong-Di; Gu, Ji-Dong; Lu, Shu-Guang; Shi, Lei; Lu, Qiang; Shen, Ting-Ting

2012-08-24

298

Biodegradation of benzene homologues in contaminated sediment of the East China Sea.  

UK PubMed Central (United Kingdom)

This study focused on acclimating a microbial enrichment to biodegrade benzene, toluene, ethylbenzene and xylenes (BTEX) in a wide range of salinity. The enrichment degraded 120 mg/L toluene within 5d in the presence of 2M NaCl or 150 mg/L toluene within 7d in the presence of 1-1.5M NaCl. PCR-DGGE (polymerase chain reaction-denatured gradient gel electrophoresis) profiles demonstrated the dominant species in the enrichments distributed between five main phyla: Gammaproteobacteria, Sphingobacteriia, Prolixibacter, Flavobacteriia and Firmicutes. The Marinobacter, Prolixibacter, Balneola, Zunongwangia, Halobacillus were the dominant genus. PCR detection of genotypes involved in bacterial BETX degradation revealed that the degradation pathways contained all the known initial oxidative attack of BTEX by monooxygenase and dioxygenase. And the subsequent ring fission was catalysed by catechol 1,2-dioxygenase and catechol 2,3-dioxygenase. Nuclear magnetic resonance (NMR) spectroscopy profiles showed that the bacterial consortium adjusted the osmotic pressure by ectoine and hydroxyectoine as compatible solutes to acclimate the different salinity conditions.

Li H; Zhang Q; Wang XL; Ma XY; Lin KF; Liu YD; Gu JD; Lu SG; Shi L; Lu Q; Shen TT

2012-11-01

299

TrgI, toluene repressed gene I, a novel gene involved in toluene-tolerance in Pseudomonas putida S12.  

UK PubMed Central (United Kingdom)

Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent efflux pump SrpABC and its regulatory genes srpRS were heavily up-regulated. The increased energy demand brought about by toluene stress was also reflected in transcriptional changes: genes involved in sugar storage were down-regulated whereas genes involved in energy generation such as isocitrate dehydrogenase and NADH dehydrogenases, were up-regulated in the presence of toluene. Several flagella-related genes were up-regulated and a large group of transport genes were down-regulated. In addition, a novel Pseudomonas-specific gene was identified to be involved in toluene tolerance of P. putida S12. This toluene-repressed gene, trgI, was heavily down-regulated immediately upon toluene exposure in batch cultures. The relationship of trgI with solvent tolerance was confirmed by the increased resistance to toluene shock and toluene induced lysis of trgI knock-out mutants. We propose that down-regulation of trgI plays a role in the first line of defence against solvents.

Volkers RJ; Ballerstedt H; Ruijssenaars H; de Bont JA; de Winde JH; Wery J

2009-03-01

300

Ethyl diazoacetate synthesis in flow  

Science.gov (United States)

Summary Ethyl diazoacetate is a versatile compound in organic chemistry and frequently used on lab scale. Its highly explosive nature, however, severely limits its use in industrial processes. The in-line coupling of microreactor synthesis and separation technology enables the synthesis of this compound in an inherently safe manner, thereby making it available on demand in sufficient quantities. Ethyl diazoacetate was prepared in a biphasic mixture comprising an aqueous solution of glycine ethyl ester, sodium nitrite and dichloromethane. Optimization of the reaction was focused on decreasing the residence time with the smallest amount of sodium nitrite possible. With these boundary conditions, a production yield of 20 g EDA day?1 was achieved using a microreactor with an internal volume of 100 ?L. Straightforward scale-up or scale-out of microreactor technology renders this method viable for industrial application.

Delville, Marielle M E; van Hest, Jan C M

2013-01-01

 
 
 
 
301

Ethyl diazoacetate synthesis in flow.  

UK PubMed Central (United Kingdom)

Ethyl diazoacetate is a versatile compound in organic chemistry and frequently used on lab scale. Its highly explosive nature, however, severely limits its use in industrial processes. The in-line coupling of microreactor synthesis and separation technology enables the synthesis of this compound in an inherently safe manner, thereby making it available on demand in sufficient quantities. Ethyl diazoacetate was prepared in a biphasic mixture comprising an aqueous solution of glycine ethyl ester, sodium nitrite and dichloromethane. Optimization of the reaction was focused on decreasing the residence time with the smallest amount of sodium nitrite possible. With these boundary conditions, a production yield of 20 g EDA day(-1) was achieved using a microreactor with an internal volume of 100 ?L. Straightforward scale-up or scale-out of microreactor technology renders this method viable for industrial application.

Delville MM; van Hest JC; Rutjes FP

2013-01-01

302

Process for producing ethyl alcohol  

UK PubMed Central (United Kingdom)

The invention refers to the food industry, namely to a process for producing ethyl alcohol. The process for producing ethyl alcohol includes crude juice obtaining from Sorghum saccharatum, acidulation thereof with an inorganic acid up to the pH 2.5...3.2 with ageing during 4...6 hours, sulphitation with sulphurous anhydride up to 50...80 mg/dm3, addition of the diffusion grape juice in a volume ratio of 1:(0.5...1), introduction of winy sediments of leavens Saccharomyces cerevisae in a volume of 2...3%, fermentation of the obtained mixture and distillation-rectification of the biomass. The result consists in improving the quality of the ethyl alcohol and increasing the production output.

PARASCA PETRU; URITU DIONIS; MORARU GHEORGHE; STICIUC MIHAI

303

Major sources of benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

Data from EPA's TEAM Study allow us to identify the major sources of exposure to benzene for much of the U.S. population. These sources turn out to be quite different from what had previously been considered the important sources. The most important source of exposure for 50 million smokers is the mainstream smoke from their cigarettes, which accounts for about half of the total population burden of exposure to benzene. Another 20% of nationwide exposure is contributed by various personal activities, such as driving and using attached garages. (Emissions from consumer products, building materials, paints, and adhesives may also be important, although data are largely lacking.) The traditional sources of atmospheric emissions (auto exhaust and industrial emissions) account for only about 20% of total exposure. Environmental tobacco smoke is an important source, accounting for about 5% of total nationwide exposure. A number of sources sometimes considered important, such as petroleum refining operations, petrochemical manufacturing, oil storage tanks, urban-industrial areas, service stations, certain foods, groundwater contamination, and underground gasoline leaks, appear to be unimportant on a nationwide basis.

Wallace, L.A. (Environmental Protection Agency, Washington, DC (USA))

1989-07-01

304

Atmospheric chemistry of ethyl propionate.  

UK PubMed Central (United Kingdom)

Ethyl propionate is a model for fatty acid ethyl esters used as first-generation biodiesel. The atmospheric chemistry of ethyl propionate was investigated at 980 mbar total pressure. Relative rate measurements in 980 mbar N(2) at 293 ± 0.5 K were used to determine rate constants of k(C(2)H(5)C(O)OC(2)H(5) + Cl) = (3.11 ± 0.35) × 10(-11), k(CH(3)CHClC(O)OC(2)H(5) + Cl) = (7.43 ± 0.83) × 10(-12), and k(C(2)H(5)C(O)OC(2)H(5) + OH) = (2.14 ± 0.21) × 10(-12) cm(3) molecule(-1) s(-1). At 273-313 K, a negative Arrhenius activation energy of -3 kJ mol(-1) is observed.. The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar N(2) gave the following products (stoichiometric yields): ClCH(2)CH(2)C(O)OC(2)H(5) (0.204 ± 0.031), CH(3)CHClC(O)OC(2)H(5) (0.251 ± 0.040), and C(2)H(5)C(O)OCHClCH(3) (0.481 ± 0.088). The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar of N(2)/O(2) (with and without NO(x)) gave the following products: ethyl pyruvate (CH(3)C(O)C(O)OC(2)H(5)), propionic acid (C(2)H(5)C(O)OH), formaldehyde (HCHO), and, in the presence of NO(x), PAN (CH(3)C(O)OONO(2)). The lack of acetaldehyde as a product suggests that the CH(3)CH(O)C(O)OC(2)H(5) radical favors isomerization over decomposition. From the observed product yields, we conclude that H-abstraction by chlorine atoms from ethyl propionate occurs 20.4 ± 3.1%, 25.1 ± 4.0%, and 48.1 ± 8.8% from the CH(3)-, -CH(2)-, and -OCH(2)- groups, respectively. The rate constant and branching ratios for the reaction between ethyl propionate and the OH radical were investigated theoretically using quantum mechanical calculations and transition state theory. The stationary points along the reaction path were optimized using the CCSD(T)-F12/VDZ-F12//BH&HLYP/aug-cc-pVTZ level of theory; this model showed that OH radicals abstract hydrogen atoms primarily from the -OCH(2)- group (80%).

Andersen VF; Ørnsø KB; Jørgensen S; Nielsen OJ; Johnson MS

2012-05-01

305

2-(1H-1,2,3-Benzotriazol-1-yl)-1-(4-ethylbenzoyl)ethyl 2,4-dichlorobenzoate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title molecule, C24H19Cl2N3, the dihedral angles between the benzotriazole group and the ethyl- and dichloro-substituted benzene rings are 16.53?(1) and 82.09?(1)°, respectively. The crystal structure is stabilized by weak intermolecular C—H...O interactions.

Wu-Lan Zeng

2008-01-01

306

Comparison between urinary o-cresol and toluene as biomarkers of toluene exposure.  

Science.gov (United States)

The characteristics of urinary o-cresol (o-C) and urinary toluene (TOL-U) as biomarkers of occupational exposure to toluene were comparatively evaluated. One hundred healthy male rotogravure printing workers and 161 male and female control subjects were studied. Personal exposure to airborne toluene (TOL-A) during the shift was determined as a time-weighted average. Simple analytical procedures based on solid phase microextraction followed by gas chromatography/mass spectometry analysis were applied to the determination of end-shift o-C and TOL-U. Median TOL-A was 48 (6.0-162.0) mg/m3 in printers and 0.021 (<0.003-0.137) mg/m3 in controls. o-C was 0.185 (0.032-0.948) mg/g creatinine in printers and 0.027 (<0.006-0.330) mg/g creatinine in the controls. TOL-U was 7.6 (1.8-23.9) microg/L in printers and 0.140 (0.094-0.593) microg/L in the controls. According to all indices, exposure to toluene was higher in printers than in the controls. Nevertheless, the distribution of o-C in the two groups partially overlapped, whereas such behavior was not found in TOL-U. Both o-C and TOL-U in printers were correlated with TOL-A (Pearson's on log10-transformed variables r = 0.704 and 0.844, respectively) and with each other (r = 0.683). Smoking habits significantly increased the excretion of o-C but not of TOL-U. From the point of view of sampling conditions and analytical requirements, TOL-U and o-C showed similar properties, but comparison of their intrinsic characteristics showed that TOL-U had higher specificity and sensitivity, lower background values, was better correlated with airborne exposure, and was not influenced by cigarette smoking. Therefore TOL-U may be considered superior to o-C as a biomarker of occupational exposure to toluene. PMID:17162475

Fustinoni, Silvia; Mercadante, Rosa; Campo, Laura; Scibetta, Licia; Valla, Carla; Consonni, Dario; Foà, Vito

2007-01-01

307

Effect of pressure on the solubilities of benzene and alkylbenzenes in water  

Energy Technology Data Exchange (ETDEWEB)

The solubilities of benzene, toluene, ethylbenzene, and n-propylbenzene in water were measured at 25{degree}C at pressures to 400 MPa (100 MPa for benzene). The maxima in the solubilities are observed at 200, 150, and 140 MPa for toluene, ethylbenzene, and n-propylbenzene, respectively. The volume changes, {Delta}V{degree}, accompanying the solution are estimated at high pressures from the pressure dependences of the solubilities. The compressions of ethylbenzene, n-propylbenzene, and m-xylene were measured at 25{degree}C up to 350 MPa with a mercury-trapped piezometer in order to estimate the molar volumes, V{degree}, of the solutes. The partial molar volumes, V{degree}, of benzene and alkylbenzenes in water at high pressures up to 400 MPa were estimated from the {Delta}V{degree} and V{degree}, and the isothermal partial molar compressibilities, {beta}{sub {tau}}{degree} ({triple bond} 1/V{degree} ({delta}V{degree}/{delta}P){sub {tau}}), were also determined. The {beta}{sub {tau}}{degree} of ethylbenzene and n-propylbenzene at atmospheric pressure were -1.6 {times} 10{sup {minus}4} and {minus}2.1 {times} 10{sup {minus}4} MPa{sup {minus}1}, respectively; these quantities became positive at ca. 50 MPa. The {beta}{sub {tau}}{degree} for the other solutes were positive and decreased with increasing pressure. The compressibilities, {beta}{sub h}, of the hydration shells around the solutes were estimated by a model of the hydration state. The results suggest that the hydration shell is destroyed by compression and disappears above 100 MPa.

Sawamura, Seiji; Kitamura, Kiyoshi; Taniguchi, Yoshihiro (Ritsumeikan Univ., Kyoto (Japan))

1989-06-15

308

1,4-Bis(1,1-dimethyl-prop-yl)-2,5-dimeth-oxy-benzene.  

UK PubMed Central (United Kingdom)

The title compound, C(18)H(30)O(2), was prepared by Friedel-Crafts alkyl-ation of 1,4-dimeth-oxy-benzene with 2-methyl-2-butanol. The complete mol-ecule is generated by the application of a crystallographic centre of inversion. The two meth-oxy groups are oriented in the same plane of the aromatic ring [C-C-O-C torsion angle = 9.14?(16)°]. While one methyl group of the tert-pentyl substituent is coplanar with the benzene ring [C-C-C-C = 0.45?(15)°] and lies towards the less-hindered H atom, the other methyl and ethyl groups are directed to either side of the benzene ring [C-C-C-C torsion angles = 118.78?(12) and 59.11?(14)°, respectively]. In the crystal, the hydro-phobic mol-ecules pack to form a brick-wall-like architecture.

Amimoto K

2011-10-01

309

1,4-Bis(1,1-dimethyl-prop-yl)-2,5-dimeth-oxy-benzene.  

Science.gov (United States)

The title compound, C(18)H(30)O(2), was prepared by Friedel-Crafts alkyl-ation of 1,4-dimeth-oxy-benzene with 2-methyl-2-butanol. The complete mol-ecule is generated by the application of a crystallographic centre of inversion. The two meth-oxy groups are oriented in the same plane of the aromatic ring [C-C-O-C torsion angle = 9.14?(16)°]. While one methyl group of the tert-pentyl substituent is coplanar with the benzene ring [C-C-C-C = 0.45?(15)°] and lies towards the less-hindered H atom, the other methyl and ethyl groups are directed to either side of the benzene ring [C-C-C-C torsion angles = 118.78?(12) and 59.11?(14)°, respectively]. In the crystal, the hydro-phobic mol-ecules pack to form a brick-wall-like architecture. PMID:22058795

Amimoto, Kiichi

2011-09-30

310

Extraction and separation studies of tellurium(IV) with tris-(2-ethyl hexyl) phosphate  

Energy Technology Data Exchange (ETDEWEB)

A method is proposed for the extraction of microgram levels of tellurium(IV) from halide media with tris-(2-ethyl hexyl) phosphate dissolved in toluene as extractant. The optimum conditions have been evaluated from a critical study of acid concentration, extractant concentration, period of equilibration and effect of solvent. Tellurium ion from the organic phase is stripped with water and determined spectrophotometrically with stannous chloride. The method affords binary separation of tellurium from copper, bismuth, gold and selenium and is applicable to the analysis of alloy samples and synthetic mixtures. The method is fast, accurate and precise. (author).

Desai, G.S.; Shinde, V.M. (Institute of Science, Bombay (India). Analytical Lab.)

1992-04-01

311

The effect of toluene on oxidative processes in rat blood  

Directory of Open Access Journals (Sweden)

Full Text Available This study was designed to investigate the effects of toluene treatment on oxidative stress in rat blood. Since toluene metabolism produces reactive oxygen and nitrogen species, it was hypothesized that the toluene treatment would: 1) provoke changes in the activities of antioxidant enzymes, 2) impair the integrity of the cell membrane and 3) induce structural changes in the plasma proteins. Female Wistar rats were treated with toluene intraperitonally, at a daily dose of 0.38 mmol/kg body weight for 12 days, and 5 mmol/kg body weight for 6 days, respectively, with propylene glycol as the carrier. Toluene significantly increased superoxide dismutase activity at low doses, catalase activity at high doses and the level of erythrocytes malondialdehyde in both treated groups when compared to the control group. The nitrite (NO2-) level in both treated groups was not different from that in the control animals. Toluene caused oxidative modification of plasma proteins and, consequently, changes in the concentration of glycoproteins and lipoproteins when compared to the control group. The observed alterations indicate that toluene treatment might be involved in free radical processes.

SILVANA S. STAJKOVIC; SUNCICA Z. BOROZAN; GORDANA GADJANSKI-OMEROVIC

2009-01-01

312

Photocatalytic oxidation of toluene to benzaldehyde by molecular oxygen  

Energy Technology Data Exchange (ETDEWEB)

The visible light irradiation of aqueous solutions containing toluene, uranyl(VI) ions, and O{sub 2} results in the formation of benzaldehyde as a major product. Small amounts of PhCH{sub 2}OH are also formed. The yields of benzaldehyde are 3 times greater for toluene-h{sub 8} than for toluene-d{sub 8}, but the kinetic isotope effect for the quenching of the excited state {sup *}UO{sub 2}{sup 2+} by toluene is negligible (k{sub toluene-h(8)}/k{sub toluene-d(8)}=1.2). This and other evidence indicate that the quenching takes place in two parallel pathways. The major one involves the aromatic portion of tolune and leads to the recovery of the reactants. The minor, productive path takes place by hydrogen atom abstraction from the methyl group, followed by the oxidation of PhCH{sub 2}{sup {center_dot}}. Cumene, benzyl alcohol, and benzaldehyde react similarly. 31 refs., 5 figs., 1 tab.

Mao, Y.; Bakac, A. [Ames LAb., IA (United States)]|[Iowa State Univ., Ames, IA (United States)

1996-03-07

313

Ethyl 4-(1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-2-yl)benzoate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C21H15NO4, was synthesized by reducing the Schiff base obtained from acenaphthenequinone and ethyl-4-aminobenzoate. The dihedral angle between the essentially planar 1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinoline ring system [maximum deviation = 0.061?(2)?Å] and the benzene ring is 75.08?(10)°. In the crystal, molecules are connected via weak intermolecular C—H...O hydrogen bonds, forming a two-dimensional network. The ethyl group is disordered over two sets of sites with a refined occupancy ratio of 0.502?(12):0.498?(12).

Yi Chen Chan; Abdussalam Salhin; Melati Khairuddean; Madhukar Hemamalini; Hoong-Kun Fun

2011-01-01

314

Characterization of the triplet state of tris(8-hydroxyquinoline)aluminium(III) in benzene solution.  

UK PubMed Central (United Kingdom)

The lowest triplet state of tris(8-hydroxyquinoline)aluminium(III) (Alq3) has been prepared by pulse radiolysis/energy transfer from appropriate donors in benzene solutions and has an absorption maximum around 510 nm with a lifetime of about 50 mus. It is quenched by molecular oxygen, leading to singlet oxygen formation. From flash photolysis and singlet oxygen formation measurements, a quantum yield of triplet formation of 0.24 was determined for direct photolysis of the complex. A value of 2.10 +/- 0.10 eV was determined for the energy of the lowest triplet state by energy transfer studies and was confirmed by phosphorescence measurements on Alq3, either in the heavy atom solvent ethyl iodide or photosensitized by benzophenone in benzene. Dexter (exchange) energy transfer was observed from triplet Alq3 to platinum(II) octaethylporphyrin.

Burrows HD; Fernandes M; Seixas de Melo J; Monkman AP; Navaratnam S

2003-12-01

315

Solubility of phosphonium ionic liquid in alcohols, benzene, and alkylbenzenes.  

Science.gov (United States)

The (solid + liquid) phase equilibria and (liquid + liquid) phase equilibria of binary mixtures containing quaternary phosphonium salt-tetrabutylphosphonium methanesulfonate and alcohols or alkylbenzenes were investigated. The systems {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + 1-butanol, or 1-hexanol, 1-octanol, 1-decanol, or 1-dodecanol} and {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + benzene, or toluene, ethylbenzene, or propylbenzene} have been measured by a dynamic method at a wide range of temperatures from 220 to 386 K. Solid-liquid equilibria with immiscibility in the liquid phase were detected with the aromatic hydrocarbons ethylbenzene and propylbenzene. The basic thermodynamic properties of pure ionic liquid--the melting point, enthalpy of fusion, enthalpy of solid-solid-phase transition, and glass transition--have been determined by differential scanning calorimetry. The experimental data of systems with alcohols were correlated by means of the UNIQUAC ASM and NRTL1 equations and of systems with alkylbenzenes with Wilson and NRTL equations utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular equation used. PMID:17391024

Doma?ska, Urszula; Casás, Lidia M

2007-03-29

316

Solubility of phosphonium ionic liquid in alcohols, benzene, and alkylbenzenes.  

UK PubMed Central (United Kingdom)

The (solid + liquid) phase equilibria and (liquid + liquid) phase equilibria of binary mixtures containing quaternary phosphonium salt-tetrabutylphosphonium methanesulfonate and alcohols or alkylbenzenes were investigated. The systems {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + 1-butanol, or 1-hexanol, 1-octanol, 1-decanol, or 1-dodecanol} and {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + benzene, or toluene, ethylbenzene, or propylbenzene} have been measured by a dynamic method at a wide range of temperatures from 220 to 386 K. Solid-liquid equilibria with immiscibility in the liquid phase were detected with the aromatic hydrocarbons ethylbenzene and propylbenzene. The basic thermodynamic properties of pure ionic liquid--the melting point, enthalpy of fusion, enthalpy of solid-solid-phase transition, and glass transition--have been determined by differential scanning calorimetry. The experimental data of systems with alcohols were correlated by means of the UNIQUAC ASM and NRTL1 equations and of systems with alkylbenzenes with Wilson and NRTL equations utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular equation used.

Doma?ska U; Casás LM

2007-04-01

317

A mechanism describing the photochemical oxidation of toluene in smog  

Energy Technology Data Exchange (ETDEWEB)

The photo-oxidation of toluene/NO/sub x/ exhibits several features that distinquish it from olefin and paraffin smog systems: highly photolytic products, a relatively low production rate of peroxy radicals, and strong sinks for NO/sub x/. The underlying chemical behavior of the toluene smog system is discussed and a kinetic simulation mechanism is presented. The mechanism simulates toluene smog chamber experiments conducted at two facilities: the University of California at Riverside evacuable chamber, and the outdoor smog chamber at the University of North Carolina.

Killus, J.P.; Whiten, G.Z.

1982-01-01

318

In vitro antiperoxidative, free radical scavenging and xanthine oxidase inhibitory potentials of ethyl acetate fraction of Saraca ashoka flowers.  

Science.gov (United States)

Saraca ashoka is a widely used medicinal herb claimed to cure many diseases. This study investigated the antiperoxidative, free radical scavenging and xanthine oxidase (XO) inhibitory potential of the ethyl acetate fraction of S. ashoka flowers (SAF) and compared it with standard compounds like gallic acid, ascorbic acid, butylated hydroxyl toluene and allopurinol. The ethyl acetate fraction of SAF exhibited free radical scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and superoxide radical, along with hydroxyl radical scavenging activity. Lipid peroxidation inhibitory potential of SAF was studied using a linoleic acid emulsion system, which shows significant antioxidant potential. SAF also demonstrated significant XO (key enzyme linked to inflammation) inhibitory activity, which revealed its therapeutic potential as an antioxidant and XO inhibitor. HPLC profiling of the ethyl acetate fraction of SAF revealed that it contains ellagic acid as a major compound and thus the beneficial effects of this fraction may be due to the presence of this compound. PMID:21294042

Prathapan, A; Lijo Cherian, O; Nampoothiri, Suresh V; Mini, S; Raghu, K G

2011-02-01

319

In vitro antiperoxidative, free radical scavenging and xanthine oxidase inhibitory potentials of ethyl acetate fraction of Saraca ashoka flowers.  

UK PubMed Central (United Kingdom)

Saraca ashoka is a widely used medicinal herb claimed to cure many diseases. This study investigated the antiperoxidative, free radical scavenging and xanthine oxidase (XO) inhibitory potential of the ethyl acetate fraction of S. ashoka flowers (SAF) and compared it with standard compounds like gallic acid, ascorbic acid, butylated hydroxyl toluene and allopurinol. The ethyl acetate fraction of SAF exhibited free radical scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and superoxide radical, along with hydroxyl radical scavenging activity. Lipid peroxidation inhibitory potential of SAF was studied using a linoleic acid emulsion system, which shows significant antioxidant potential. SAF also demonstrated significant XO (key enzyme linked to inflammation) inhibitory activity, which revealed its therapeutic potential as an antioxidant and XO inhibitor. HPLC profiling of the ethyl acetate fraction of SAF revealed that it contains ellagic acid as a major compound and thus the beneficial effects of this fraction may be due to the presence of this compound.

Prathapan A; Lijo Cherian O; Nampoothiri SV; Mini S; Raghu KG

2011-02-01

320

METHOD FOR MAKING METHYL ETHYL KETONE CYANOHYDRIN  

UK PubMed Central (United Kingdom)

The invention concerns a method for making ketone methyl ethyl cyanohydrin of formula (I) characterised in that it consists in reacting hydrocyanic acid and ketone methyl ethyl in the presence of diethylamine as catalyst.

CROIZY JEAN-FRANCOIS; ESCH MARC; ESQUIROL GILBERT

 
 
 
 
321

21 CFR 573.420 - Ethyl cellulose.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Ethyl cellulose. 573.420 Section 573.420 Food and...Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in...

2010-04-01

322

Benzene and lymphohematopoietic malignancies in humans.  

UK PubMed Central (United Kingdom)

BACKGROUND: Quantitative evaluations of benzene-associated risk for cancer have relied primarily on findings from a cohort study of highly exposed U.S. rubber workers. An epidemiologic investigation in China (NCI/CAPM study) extended quantitative evaluations of cancer risk to a broader range of benzene exposures, particularly at lower levels. METHODS: We review the evidence implicating benzene in the etiology of hematopoietic disorders, clarify methodologic aspects of the NCI/CAPM study, and examine the study in the context of the broader literature on health effects associated with occupational benzene exposure. RESULTS: Quantitative relationships for cancer risk from China and the U.S. show a relatively smooth increase in risk for acute myeloid leukemia and related conditions over a broad dose range of benzene exposure (below 200 ppm-years mostly from the China study and above 200 ppm-years mostly from the U.S. study). CONCLUSIONS: Risks of acute myeloid leukemia and other malignant and nonmalignant hematopoietic disorders associated with benzene exposure in China are consistent with other information about benzene exposure, hematotoxicity, and cancer risk, extending evidence for hematopoietic cancer risks to levels substantially lower than had previously been established. Published 2001 Wiley-Liss, Inc.

Hayes RB; Songnian Y; Dosemeci M; Linet M

2001-08-01

323

Apparent Benzene Solubility in Tetraphenylborate Slurries  

Energy Technology Data Exchange (ETDEWEB)

Personnel conducted testing to determine the apparent solubility of benzene in potassium tetraphenylborate (KTPB) slurries. The lack of benzene vapor pressure suppression in these tests indicate that for a 6.5 wt percent solids KTPB slurry in 4.65 M Na+ salt solution at approximately 25 degrees Celsius, no significant difference exists between the solubility of benzene in the slurry and the solubility of benzene in salt solution without KTPB solids. The work showed similar results in slurry with 6,000 mg/L sludge and 2,000 mg/L monosodium titanate added. Slurries containing tetraphenylborate decomposition intermediates (i.e., 4,200 mg/L triphenylboron (3PB), 510 mg/L diphenylborinic acid (2PB) and 1,500 mg/L phenylboric acid (1PB) or 100 mg/L tri-n-butylphosphate (TBP)) also showed no significant difference in benzene solubility form filtrate containing no KTPB solids. Slurry containing 2,000 mg/L Surfynol 420 did exhibit significant additional benzene solubility, as did irradiated slurries. The vapor pressure depression in the irradiated slurries presumably results from dissolution of biphenyl and other tetraphenylborate irradiation products in the benzene.

Swingle, R.F.; Peterson, R.A.; Crawford, C.L.

1997-11-01

324

Examination on colour reaction of nicotinic acid-ethyl violet-uranyl ternary complex by solvent extraction spectrophotometry  

International Nuclear Information System (INIS)

[en] The test examination was made on solvent extraction colour reaction of the ternary complex formed by nicotinic acid, ethyl violet and uranyl in cyclohexane+MIBK (methyl isobutyl ketone) or benzene+MIBK. A difference was found between the published results and the authors'. It was shown that there is no chromomagnetic dependence with uranyl ion, but the approximate linear correlation is present with NO3- ion

1994-01-01

325

Toluene abuse and white matter: a model of toxic leukoencephalopathy.  

UK PubMed Central (United Kingdom)

The brain is the primary target of toluene (methylbenzene), the major solvent in spray paint and a constituent of many other easily obtained commercial and industrial products. The effects of acute intoxication can be dramatic and the lasting adverse effects of inhalants may be highly injurious. Mental status alterations range from acute confusional state to coma. Toluene abuse effects on white matter are demonstrable neuroradiologically and neuropathologically, and have important neurobehavioral consequences.

Filley CM

2013-06-01

326

Method for producing bis(trifluoromethyl)benzene  

UK PubMed Central (United Kingdom)

The invention relates to a method for producing a bis(trifluoromethyl)benzene. This method includes the steps of (a) chlorinating a compound represented by the general formula (1) by chlorine, thereby to produce a trichloromethyltrifluoromethylbenzene; and (b) fluorinating the trichloromethyltrifluoromethylbenzene by hydrogen fluoride, thereby to produce the bis(trifluoromethyl)benzene, where m is 1, 2 or 3. It is not necessary in the invention to handle solid in any reaction step. Therefore, the invention is very useful in the production of a bis(trifluoromethyl)benzene in an industrial scale.

ISHIDA MICHIO; KOIDE MAKOTO; KATSUHARA YUTAKA

327

A method for producing high octane benzene  

Energy Technology Data Exchange (ETDEWEB)

The method for producing high octane benzene, which involves the multi-stage catalytic reformation of benzene fractions at a higher temperature and pressure, is improved by subjecting the reformation products to rectification before the final stage, producing a primary fraction with a final boiling temperature of 105-120 degrees and a settling fraction; the settling fraction is given the last injections at the final reformation stage, and the products are mixed with the primary fraction in order to increase the yield and quality of benzene.

Akhmetov, A.F.; Ivanov, A.F.; Tanatarov, M.A.

1982-01-01

328

Semicontinuous microcosm study of aerobic cometabolism of trichloroethylene using toluene  

Energy Technology Data Exchange (ETDEWEB)

A semicontinuous slurry-microcosm method was applied to mimic trichloroethylene (TCE) cometabolic biodegradation field results at the Que-Jen in-situ pilot study. The microcosm study confirmed the process of aerobic cometabolism of TCE using toluene as the primary substrate. Based on the nucleotide sequence of 16S rRNA genes, the toluene-oxidizing bacteria in microcosms were identified, i.e. Ralstonia sp. P-10 and Pseudomonasputida. The first-order constant of TCE-degradation rate was 0.5 day{sup -1} for both Ralstonia sp. P-10 and P.putida. The TCE cometabolic-biodegradation efficiency measured from the slurry microcosms was 46%, which appeared pessimistic compared to over 90% observed from the in-situ pilot study. The difference in the TCE cometabolic-biodegradation efficiency was likely due to the reactor configurations and the effective time duration of toluene presence in laboratory microcosms (1 days) versus in-situ pilot study (3 days). The results of microcosm experiments using different toluene-injection schedules supported the hypothesis. With a given amount of toluene injection, it is recommended to maximize the effective time duration of toluene presence in reactor design for TCE cometabolic degradation.

Han, Y.L. [Department of Mineral and Petroleum Engineering, National Cheng Kung University, 1 University Avenue, Tainan 701, Taiwan (China); Kuo, M.C. Tom [Department of Mineral and Petroleum Engineering, National Cheng Kung University, 1 University Avenue, Tainan 701, Taiwan (China)], E-mail: mctkuobe@mail.ncku.edu.tw; Tseng, I.C. [Department of Life Sciences, National Cheng Kung University, 1 University Avenue, Tainan 701, Taiwan (China); Lu, C.J. [Department of Environmental Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China)

2007-09-30

329

Toluene mediated oxidative stress and granulo-monocytopoiesis  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of toluene exposure on some biochemical and hematological parameters was investigated in adult female Wistar rats. The animals were subjected to intraperitoneal administration of toluene diluted in propylene glycol and the diluent alone for 3, 7 and 11 consecutive days at the same time intervals. The effects of toluene and propylene glycol were evaluated biochemically by determining the plasma concentrations of total proteins albumin and ceruloplasmin (Cp) together with erythrocyte malondialdehyde (MDA), and hematological indices from peripheral blood and bone marrow. The biochemical acute phase response was manifested by an elevated Cp concentration in all experimental animals. The markedly enhanced MDA concentration and statistically significant decrease in albumin level in toluene treated rats, indicated damage, to blood vessel endothelia. Alterations of leukocytes of peripheral blood and bone marrow (BM) granulocytic-monocytic progenitor cells were typical of an inflammatory response, with stimulation of granulo-monocytopoiesis. Therefore, it can be assumed that both toluene and propylene glycol mediated sterile peritonitis and oxidative stress injury, with changes intensified by toluene action.

Boži? Tatjana P.; Stevanovi? Jelka Ž.; Kova?evi? Milica M.; Jovi? Slavoljub Z.; Luki? Sanja; Petakov Marijana D.; Borozan Sun?ica Z.; Mija?evi? Zora M.; Kneževi? Milijana A.; Bulaji? Snežana B.

2003-01-01

330

Toluene diffusion and reaction in unsaturated Pseudomonas putida biofilms  

Energy Technology Data Exchange (ETDEWEB)

Biofilms are frequently studied in the context of submerged or aquatic systems. However, much less is known about biofilms in unsaturated systems, despite their importance to such processes as food spoilage, terrestrial nutrient cycling, and biodegradation of environmental pollutants in soils. Using modeling and experimentation, the authors have described the biodegradation of toluene in unsaturated media by bacterial biofilms as a function of matric water potential, a dominant variable in unsaturated systems. They experimentally determined diffusion and kinetic parameters for Pseudomonas putida biofilms, then predicted biodegradation rates over a range of matric water potentials. For validation, the authors measured the rate of toluene depletion by intact biofilms and found the results to reasonably follow the model predictions. The diffusion coefficient for toluene through unsaturated P. putida biofilm averaged 1.3 {times} 10{sup {minus}7} cm{sup 2}/s, which is approximately two orders of magnitude lower than toluene diffusivity in water. Their studies show that, at the scale of the microbial biofilm, the diffusion of toluene to biodegrading bacteria can limit the overall rate of biological toluene depletion in unsaturated systems.

Holden, P.A.; Hunt, J.R.; Firestone, M.K. [Univ. of California, Berkeley, CA (United States)

1997-12-20

331

Studies of the Cataluminescence of Benzene Homologues onNanosized γ–Al2O3/Eu2O3 and the Development of a Gas Sensorfor Benzene Homologue Vapors  

Directory of Open Access Journals (Sweden)

Full Text Available The cataluminescence (CTL) of benzene and the benzene homologues tolueneand xylene on nanosized γ–Al2O3 doped with Eu2O3 (γ–Al2O3/Eu2O3) was studied and asensor of determining these gases was designed. The proposed sensor showed highsensitivity and selectivity at an optimal temperature of 432 ºC, a wavelength of 425 nm anda flow rate of 400 mL/min. Quantitative analysis was performed at the optimal conditions.The linear ranges of CTL intensity versus concentration of the benzene homologues were asfollows: benzene 2.4~5000 mL/m3, toluene 4.0~5000 mL/m3 and xylene 6.8~5000 mL/m3,with detection limits (3σ) of 1.8 mL/m3, 3.0 mL/m3 and 3.4 mL/m3 for each one,respectively. The response time of this system was less than 3 s. The coexistence of othergases, such as SO2, CO and NH3, caused interference at levels around 11.7%, 5.8% and8.9% respectively. The technique is a convenient and fast way of determining the vapors ofbenzene homologues in air.

Jieshan Lu; Xiaoan Cao; Canying Pan; Lianfeng Yang; Guangbo Lai; Jianling Chen; Cuiqin Wu

2006-01-01

332

Benzene and ethylene in Bio-SNG production. Nuisance, fuel or valuable products?  

Energy Technology Data Exchange (ETDEWEB)

Gasification of biomass with the aim to produce Substitute Natural Gas (SNG) is best performed at temperatures around 850C, where 50% of the combustion value of the producer gas is concentrated in hydrocarbons. After removal of the heavy hydrocarbons (i.e. tar) and sulphur components, the producer gas can be converted catalytically to a mixture of mainly methane, carbon dioxide and water. Using producer gas as intermediate instead of syngas can lead to 10% higher efficiency, as producer gas does contain a significant amount of methane already and because less heat is evolved in the conversion of the remainder than for a mixture of carbon monoxide and hydrogen. Some of the hydrocarbons in producer gas, notably benzene, toluene, acetylene and ethylene, together with some of the more volatile tar compounds, can be a nuisance in the conversion step, as they easily form carbon deposits on the methanation catalysts involved. Several strategies can be followed to make these annoying components useful. Here, we will focus on benzene and ethylene, as each represents nearly 90% of the total amount of aromatic and unsaturated hydrocarbons respectively in biomass producer gas. One approach, followed in the SNG demonstration plant in Guessing, is to remove benzene nearly completely from producer gas in a low-temperature scrubber. Recovered benzene with some of the scrubbing liquid is used as fuel to provide heat for the gasifier. Any benzene remaining in the producer gas and ethylene are converted in the fluidized bed methanation reactor. The fluidized bed creates conditions in which carbon deposits are gasified before they can harm the catalyst performance. The use of benzene as heat source in the gasifier reduces the need to burn part of the producer gas for that purpose. Effectively, more 'clean' producer gas becomes available for the methanation step. The MILENA type gasifier developed by ECN has a lower heat demand than the Guessing FICFB gasifier. Consequently, it has no use for benzene as an additional heat source. That is why ECN research focuses on solving problems associated with the conversion of benzene and ethylene to methane. One of the problems is removal of organic sulphur compounds, especially thiophene and its derivatives like benzo-thiophene. The main route pursued by ECN is conversion of thiophenes by a hydrodesulphurization (HDS) catalyst, followed by adsorption of the hydrogensulphide produced. Benzene removed from producer gas by liquid scrubbing or adsorption to a solid sorbent can also be recovered for use as fuel in a separate boiler. An advantage of that approach would be that benzene can be stored more easily than producer gas to match heat production with demand by e.g. a district heat system or to provide heat during gasifier maintenance. In fact, that would copy the approach followed in Harbooere with tar. Another promising option is cryogenic separation of producer gas. In principle, that would make it possible to separate and recover not only benzene but also ethylene. Even without purification, these may have more value as chemical base materials than when used as fuel. The cryogenic treatment would probably also capture sulphur compounds, thus considerably simplifying the gas cleaning needed for protection of the methanation catalyst. Advantages and disadvantages of the above options will be discussed. Experimental results of ECN research on hydrodesulphurization and adsorbents will be presented. Further research questions will be addressed.

Rabou, L.P.L.M. Rabou; Van der Drift, A. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

2011-11-15

333

3-Ethyl-4-[(E)-2-methylbenzylideneamino]-1H-1,2,4-triazole-5(4H)-thione  

Directory of Open Access Journals (Sweden)

Full Text Available Crystals of the title compound, C12H14N4S, were obtained from a condensation reaction of 4-amino-3-ethyl-1H-1,2,4-triazole-5(4H)-thione and 2-methylbenzaldehyde. In the molecular structure, there is a short N=C double bond [1.255?(2)?Å], and the benzene and triazole rings are located on opposite sites of this double bond. The two rings are approximately parallel to each other, the dihedral angle being 1.75?(11)°. A partially overlapped arrangement is observed between the nearly parallel triazole and benzene rings of adjacent molecules; the perpendicular distance of the centroid of the triazole ring from the benzene ring is 3.482?Å, indicating the existence of ?–? stacking in the crystal structure.

Shan-Heng Wang; Ying-Li Xu; Pei-Jin Xie; Wen-Long Wang; Shang Shan

2008-01-01

334

Methyl rotor dependent vibrational interactions in toluene.  

UK PubMed Central (United Kingdom)

The methyl rotor dependence of a three state Fermi resonance in S1 toluene at ?460 cm(-1) has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a(") 1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the "zero-order," locally coupled states. It is shown that this is the result of the local "zero-order" states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the ?m = ±3n (n = 1, 2, ...) coupling selection rule associated with torsion-rotation coupling in combination with the m(2) scaling of the rotor energies, which changes the ?E for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors.

Gascooke JR; Lawrance WD

2013-04-01

335

Methyl rotor dependent vibrational interactions in toluene.  

Science.gov (United States)

The methyl rotor dependence of a three state Fermi resonance in S1 toluene at ?460 cm(-1) has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a(") 1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the "zero-order," locally coupled states. It is shown that this is the result of the local "zero-order" states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the ?m = ±3n (n = 1, 2, ...) coupling selection rule associated with torsion-rotation coupling in combination with the m(2) scaling of the rotor energies, which changes the ?E for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors. PMID:23574222

Gascooke, Jason R; Lawrance, Warren D

2013-04-01

336

Letter Regarding Benzene Levels in Soft Drinks  

Science.gov (United States)

... You cite this list as evidence that the beverage industry has not eliminated the chemical combination that can form benzene. ... More results from www.fda.gov/food/foodborneillnesscontaminants/chemicalcontaminants

337

Spectra of isotopically mixed benzene trimers  

International Nuclear Information System (INIS)

[en] Isotopically mixed jets of benzene produced important new detailed structural results from the various possible isotopic benzene trimers in a supersonic jet. From different isotopic spectral shifts, a detailed and consistent model of the interaction between the three benzene molecules can be inferred. The splitting of the 0--0 transition of isotopically mixed trimers can be predicted from this model. This model is consistent with a ''zig--zag'' structure for the trimer, not a cyclic structure. In contrast to the dimer spectra, van der Waals modes were observed. We also discovered an important, new exciton splitting in the van der Waals modes. This splitting demonstrates for the first time that the van der Waals modes are uncoupled from molecular vibrations. Furthermore, it is a sensitive indicator of the identity of the molecules so coupled. The spectra of higher benzene clusters (dimer to pentamer) have also been measured

1989-02-01

338

Spectra of isotopically mixed benzene trimers  

Energy Technology Data Exchange (ETDEWEB)

Isotopically mixed jets of benzene produced important new detailed structural results from the various possible isotopic benzene trimers in a supersonic jet. From different isotopic spectral shifts, a detailed and consistent model of the interaction between the three benzene molecules can be inferred. The splitting of the 0--0 transition of isotopically mixed trimers can be predicted from this model. This model is consistent with a ''zig--zag'' structure for the trimer, not a cyclic structure. In contrast to the dimer spectra, van der Waals modes were observed. We also discovered an important, new exciton splitting in the van der Waals modes. This splitting demonstrates for the first time that the van der Waals modes are uncoupled from molecular vibrations. Furthermore, it is a sensitive indicator of the identity of the molecules so coupled. The spectra of higher benzene clusters (dimer to pentamer) have also been measured.

Boernsen, K.O.; Lin, S.H.; Selzle, H.L.; Schlag, E.W.

1989-02-01

339

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...5)). Examples of conditions that could make a referral unnecessary despite abnormal blood limits are iron or folate deficiency, menorrhagia, or blood loss due to some unrelated medical abnormality. Symptoms and signs of benzene...

2010-07-01

340

Enhanced ?-frustration in carbo-benzenic chromophores.  

UK PubMed Central (United Kingdom)

The synthesis, structure, and absorption spectra of highly ?-frustrated carbo-benzenes with indolic enamine substituents more or less directly conjugated to the C18 macro-aromatic core are described, and their peculiar reactivity is analyzed.

Baglai I; Maraval V; Bijani C; Saffon-Merceron N; Voitenko Z; Volovenko YM; Chauvin R

2013-08-01

 
 
 
 
341

Effect of dioxan and toluene as solvents on: Polycondensation leading to poly (2.5-furylene vinylene)s  

International Nuclear Information System (INIS)

This paper describes the influence of two different solvents, on a synthetic route leading to linear poly (2.5-furylene vinylene)s PFV, which involves the polycondensation of 5-methyl furfural in a basic medium, and on the characterization of PFV. The replacement of benzene by dioxan gives a linear polymeric structure possessing a high degree of conjugation, a good degree of polymerization, a remarkable stability to storage under ordinary condition and a partial solubility in common solvents, especially methylene chloride. Casting films from solution polymer gives brittle material, without any mechanical strength. However, the product obtained by using the toluene differs from the expected polymer. The results indicate that the raising of the degree of polymerization was done by increasing the time of reaction and successively introducing the monomer. Monomer, and dimer are isolated and characterized from the sub-product (oligomer) of the reaction. (author)

2008-01-01

342

Benzene and leukemia: An epidemiologic risk assessment  

Energy Technology Data Exchange (ETDEWEB)

To assess quantitatively the association between benzene and leukemia, the authors evaluated the rate of mortality experienced by a cohort occupationally exposed to benzene. Using data from historical air sampling surveys, they estimated the daily benzene exposure for each member of the cohort. The expected number of leukemia deaths was calculated and compared to the actual number of leukemia deaths that occurred. The overall standardized mortality ratio (SMR) for leukemia was 337. Person-years at risk within the cohort were stratified by increasing levels of cumulative benzene exposure. The resulting SMRs increased from 109 to 322 to 1,186 and to 6,637 with respective increases in cumulative benzene exposure from less than 40 ppm-years to 40-199, 200-399, and greater than 400. The shape of the exposure-response relation was examined with a case-control analysis. All of the analyses demonstrated that a strongly positive exposure-response relationship exists between benzene and leukemia. Previous attempts to quantify this cohort's risk of developing leukemia were based on surrogates of exposure, such as duration of employment. Using actual air sampling data to estimate individual exposures represents a marked improvement over these previous attempts and emphasizes the importance of conducting industrial hygiene surveys and maintaining historical exposure records.

Rinsky, R.A. (National Institute of Occupational Health and Safety, Cincinnati, OH (USA))

1989-07-01

343

Condensed phase behaviour of ionic liquid-benzene mixtures: congruent melting of a [emim][NTf2].C6H6 inclusion crystal.  

UK PubMed Central (United Kingdom)

The solid-liquid phase diagram of the (1-ethyl-3-methylimidazolium bis{(trifluoromethyl) sulfonyl} amide + benzene) system was determined and allowed us to identify and characterize an equimolar inclusion compound, [emim][NTf2].C6H6, with a congruent melting temperature: this type of behaviour, reported here for the first time, together with the X-ray structure of the inclusion compound lays emphasis upon the interactions that are responsible for the existence of liquid clathrates at higher benzene concentrations.

Lachwa J; Bento I; Duarte MT; Lopes JN; Rebelo LP

2006-06-01

344

Audition and exhibition to toluene - a contribution for the theme  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: With the technological advances and the changes in the productive processes, the workers are displayed the different physical and chemical agents in its labor environment. The toluene is solvent an organic gift in glues, inks, oils, amongst others. Objective: To compare solvent the literary findings that evidence that diligent displayed simultaneously the noise and they have greater probability to develop an auditory loss of peripheral origin. Method: Revision of literature regarding the occupational auditory loss in displayed workers the noise and toluene. Results: The isolated exposition to the toluene also can unchain an alteration of the auditory thresholds. These audiometric findings, for ototoxicity the exposition to the toluene, present similar audiograms to the one for exposition to the noise, what it becomes difficult to differentiate a audiometric result of agreed exposition - noise and toluene - and exposition only to the noise. Conclusion: The majority of the studies was projected to generate hypotheses and would have to be considered as preliminary steps of an additional research. Until today the agents in the environment of work and its effect they have been studied in isolated way and the limits of tolerance of these, do not consider the agreed expositions. Considering that the workers are displayed the multiples agent and that the auditory loss is irreversible, the implemented tests must be more complete and all the workers must be part of the program of auditory prevention exactly displayed the low doses of the recommended limit of exposition.

Augusto, Lívia Sanches Calvi; Kulay, Luiz Alexandre; Franco, Eloisa Sartori

2012-01-01

345

Similarities of toluene and o-cresol neuroexcitation in rats.  

Science.gov (United States)

Exposure to high concentrations of toluene vapors, or to intravenous o-cresol (a toluene metabolite) at about 0.9 mg/min, caused excitation of the somatosensory evoked potential (SEP) and EEG of Fischer 344 rats. SEP excitation was characterized by a large increase in a positive waveform at about 20-50 msec. Prolonged exposure to either compound caused numerous oscillations to appear from 20 msec to the end of the recording (150 msec). Both substances induced an increase in EEG beta activity and caused a large increase in activity at 5 Hz. Toluene exposed rats were lightly anesthetized, while o-cresol rats were conscious but hyperreactive. If exposure was continued, both sets of rats had involuntary muscle movements and tremors. Benzoic acid and hippuric acid, also metabolites of toluene, were similarly tested. Neither caused neuroexcitation (about 2.4 mg/min IV, 144 mg total dose). It was concluded, therefore, that metabolically derived cresols are plausible candidates for the neuroexcitatory properties of toluene. PMID:2818714

Mattsson, J L; Albee, R R; Gorzinski, S J

346

Toluene removal in a biofilm reactor for waste gas treatment  

DEFF Research Database (Denmark)

A lab-scale trickling filter for treatment of toluene-containing waste gas was investigated. The filter performance was investigated for various loads of toluene. Two levels of the gas flow were examined, 322 m d(-1) and 707 m d(-1). The gas inlet concentrations were varied in the range from 0.6 to 4.0 g m(-3). The toluene elimination increased linearly with increasing load, and at maximum load the elimination was 50 g m(-3) h(-1) (70% purification efficiency). This was in accordance with reported values for toluene removal in trickling filters. The removal was determined by the gas/liquid mass transfer and the biological degradation as well. An analytical model described the toluene removal as a half-order removal by use of two sets of parameters for the gas/liquid mass transfer and the biological degradation due to the two different gas flows. The mass transfer coefficients and the surface removal rates estimated by parameter fitting corresponded to previously observed values. The effect of the gas flow on the mass transfer coefficient and the biological removal rate may be explained by different flow patterns of the gas and the liquid phases. A characterisation of the biofilm showed an almost even biofilm growth over the filter height, which was in accordance with a constant liquid concentration throughout the column. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Pedersen, A.R.; Arvin, E.

1997-01-01

347

Performance and properties of nanoscale calcium peroxide for toluene removal.  

UK PubMed Central (United Kingdom)

Due to the large diameter and small surface, the contaminant degradation by conventional calcium peroxide (CaO2) is slow with high dosage required. The aggregation of conventional CaO2 also makes it difficult to operate. Nanoscale CaO2 was therefore synthesized and applied to remove toluene in this study. Prepared from nanoscale Ca(OH)2 and H2O2 in the ratio of 1:7, the finely dispersed nanoscale CaO2 particles were confirmed by the scanning electron microscope to be in the range of 100-200nm in size. Compared to their non nanoscale counterparts, the synthesized nanoscale CaO2 demonstrated a superior performance in the degradation of toluene, which could be eliminated in 3d at pH 6. The oxidation products of toluene were analyzed to include benzyl alcohol, benzaldehyde and three cresol isomers. With the addition of 2-propanol, hydroxyl radicals were indicated as the main reactive oxygen species in the oxidation of toluene by nanoscale CaO2. Superoxide radicals were also investigated as the marker of nanoscale CaO2 in the solution. Our study thus provides an important insight into the application of nanoscale CaO2 in the removal of toluene contaminants, which is significant, especially for controlling the petroleum contaminations.

Qian Y; Zhou X; Zhang Y; Zhang W; Chen J

2013-04-01

348

Influence of organobentonite structure on toluene adsorption from water solution  

Directory of Open Access Journals (Sweden)

Full Text Available Due to increase water pollution by organic compound derived from hydrocarbons such as toluene, several alternative technologies for remediation of polluted water have been originated. In this work natural bentonites were modified with cetyltrimethylammonium (CTMA+) for obtaining organophilic bentonites. The obtained CTMA-bentonites would be suitable for use as adsorbents of toluene present in water. The influence of structural characteristics of CTMA-bentonites on their adsorption capacity was studied. It was shown that adsorption of toluene depended on homogeneous interlayer space associated with arrangements of CTMA+ paraffin-monolayer and bilayer models, accompanied by a high degree ordering of the carbon chain of organic cation in both arrangements. However, packing density would not have an evident influence on the retention capacity of these materials. The solids obtained were characterized by chemical analysis, X-ray diffractions and infrared spectroscopy. Toluene adsorption was measured by UV-visible spectrophotometer. Adsorption capacity was studied by determining adsorption isotherms and adsorption coefficient calculation. The adsorption isotherms were straight-line indicating a partition phenomenon of toluene between the aqueous and organic phase present in organophilic bentonites.

Nuria Vidal; Cristina Volzone

2012-01-01

349

Influence of organobentonite structure on toluene adsorption from water solution  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Due to increase water pollution by organic compound derived from hydrocarbons such as toluene, several alternative technologies for remediation of polluted water have been originated. In this work natural bentonites were modified with cetyltrimethylammonium (CTMA+) for obtaining organophilic bentonites. The obtained CTMA-bentonites would be suitable for use as adsorbents of toluene present in water. The influence of structural characteristics of CTMA-bentonites on their a (more) dsorption capacity was studied. It was shown that adsorption of toluene depended on homogeneous interlayer space associated with arrangements of CTMA+ paraffin-monolayer and bilayer models, accompanied by a high degree ordering of the carbon chain of organic cation in both arrangements. However, packing density would not have an evident influence on the retention capacity of these materials. The solids obtained were characterized by chemical analysis, X-ray diffractions and infrared spectroscopy. Toluene adsorption was measured by UV-visible spectrophotometer. Adsorption capacity was studied by determining adsorption isotherms and adsorption coefficient calculation. The adsorption isotherms were straight-line indicating a partition phenomenon of toluene between the aqueous and organic phase present in organophilic bentonites.

Vidal, Nuria; Volzone, Cristina

2012-12-01

350

Synthesis and characterization of toluene-3,4-dithiolatoantimony(III) derivatives with some oxygen and/or sulphur donor ligands  

Science.gov (United States)

Replacement reactions of toluene-3,4-dithiolatoantimony(III) chloride with oxygen and/or sulphur donor ligands like benzoic acid, thiobenzoic acid, thioacetic acid, phenol, thiophenol, sodium salicylate and thio glycolic acid in 1:1 molar ratio as well as disodium oxalate in 2:1 molar ratio in refluxing anhydrous benzene yielded toluene-3,4-dithiolatoantimony(III) mono oxo and/or thio carboxylic or phenolic derivatives of the general formula ? {R = OOCC 6H 5, SOCC 6H 5, SOCCH 3, OC 6H 5, SC 6H 5, OOCC 6H 4(OH) and SCH 2COOH} and ? These newly synthesized derivatives are yellow and brown solids/liquids and are soluble in common organic solvents like benzene, chloroform, dichloromethane, etc. These derivatives have been characterized by melting point determination, molecular weight determination, elemental analysis (C, H, S and Sb), spectral {UV, IR and NMR ( 1H and 13C)} and thermal (TGA, DTA and DSC) studies.

Chauhan, H. P. S.; Bhatiya, Sumit; Bakshi, Abhilasha

2009-09-01

351

Synthesis and characterization of toluene-3,4-dithiolatoantimony(III) derivatives with some oxygen and/or sulphur donor ligands.  

UK PubMed Central (United Kingdom)

Replacement reactions of toluene-3,4-dithiolatoantimony(III) chloride with oxygen and/or sulphur donor ligands like benzoic acid, thiobenzoic acid, thioacetic acid, phenol, thiophenol, sodium salicylate and thio glycolic acid in 1:1 molar ratio as well as disodium oxalate in 2:1 molar ratio in refluxing anhydrous benzene yielded toluene-3,4-dithiolatoantimony(III) mono oxo and/or thio carboxylic or phenolic derivatives of the general formula {R=OOCC(6)H(5), SOCC(6)H(5), SOCCH(3), OC(6)H(5), SC(6)H(5), OOCC(6)H(4)(OH) and SCH(2)COOH} and These newly synthesized derivatives are yellow and brown solids/liquids and are soluble in common organic solvents like benzene, chloroform, dichloromethane, etc. These derivatives have been characterized by melting point determination, molecular weight determination, elemental analysis (C, H, S and Sb), spectral {UV, IR and NMR ((1)H and (13)C)} and thermal (TGA, DTA and DSC) studies.

Chauhan HP; Bhatiya S; Bakshi A

2009-09-01

352

Synthesis, spectroscopic, thermal and antimicrobial studies of toluene-3,4-dithiolatoarsenic(III) derivatives with some oxygen and sulphur donor ligands  

Science.gov (United States)

Replacement reactions of toluene-3,4-dithiolatoarsenic(III) chloride with oxygen and sulphur donor ligands like benzoic acid, thiobenzoic acid, anhydrous sodium acetate, thioacetic acid, phenol, thiophenol, sodium salicylate and thio glycolic acid in 1:1 molar ratio as well as disodium oxalate in 2:1 molar ratio in refluxing anhydrous benzene yielded toluene-3,4-dithiolatoarsenic(III) mono oxo or thio carboxylic or phenolic derivatives of the general formula SC6H3(CH3)SAsR {where R = OOCC6H5, SOCC6H5, OOCCH3, SOCCH3, OC6H5, SC6H5, OOCC6H4(OH), SCH2COOH} and SC6H3(CH3)SAsOOC-COOAsS(CH3)C6H3S. These synthesized derivatives are yellow, yellow-brown solids/ liquids and are soluble in common organic solvents like benzene, chloroform, dichloromethane, dimethyl formamide, dimethyl sulphoxide etc. These derivatives have been characterized by melting point determination, molecular weight determination, elemental analysis (C, H, S and As), spectral {UV, IR, NMR (1H and 13C), ESI-Mass, SEM and powder X-ray diffraction} and thermal (TGA, DTA and DSC) studies. Some of these compounds have been screened for their antimicrobial activities using the disc diffusion method. These derivatives have shown good activity as antibacterial and antifungal agents on some selected bacterial and fungal strains, which increased on increasing the concentration. Chloroamphenicol and terbinafin were used as standards for the comparison.

Chauhan, H. P. S.; Bhatiya, Sumit

2012-11-01

353

Synthesis, spectroscopic, thermal and antimicrobial studies of toluene-3,4-dithiolatoarsenic(III) derivatives with some oxygen and sulphur donor ligands.  

UK PubMed Central (United Kingdom)

Replacement reactions of toluene-3,4-dithiolatoarsenic(III) chloride with oxygen and sulphur donor ligands like benzoic acid, thiobenzoic acid, anhydrous sodium acetate, thioacetic acid, phenol, thiophenol, sodium salicylate and thio glycolic acid in 1:1 molar ratio as well as disodium oxalate in 2:1 molar ratio in refluxing anhydrous benzene yielded toluene-3,4-dithiolatoarsenic(III) mono oxo or thio carboxylic or phenolic derivatives of the general formula SC(6)H(3)(CH(3))SAsR {where R=OOCC(6)H(5), SOCC(6)H(5), OOCCH(3), SOCCH(3), OC(6)H(5), SC(6)H(5), OOCC(6)H(4)(OH), SCH(2)COOH} and SC(6)H(3)(CH(3))SAsOOC-COOAsS(CH(3))C(6)H(3)S. These synthesized derivatives are yellow, yellow-brown solids/ liquids and are soluble in common organic solvents like benzene, chloroform, dichloromethane, dimethyl formamide, dimethyl sulphoxide etc. These derivatives have been characterized by melting point determination, molecular weight determination, elemental analysis (C, H, S and As), spectral {UV, IR, NMR ((1)H and (13)C), ESI-Mass, SEM and powder X-ray diffraction} and thermal (TGA, DTA and DSC) studies. Some of these compounds have been screened for their antimicrobial activities using the disc diffusion method. These derivatives have shown good activity as antibacterial and antifungal agents on some selected bacterial and fungal strains, which increased on increasing the concentration. Chloroamphenicol and terbinafin were used as standards for the comparison.

Chauhan HP; Bhatiya S

2012-11-01

354

Initiation of nucleation in overheated benzene and solution of benzene-para-terphenyl in ?-radiation field  

International Nuclear Information System (INIS)

The influence of a small addition (0.16 mol%) of paraterphenyl scintillator on radiation sensitivity of overheated benzene was studied. It is found that the presence of terphenyl decreases noticeably the frequency of initiated nucleation in benzene. The effect observed is explained from the viewpoint of luminescence influence on the process of vapour phase nucleation in metastable liquid. 8 refs., 2 figs.

1993-01-01

355

Method for preparing quizalofop-p-ethyl  

UK PubMed Central (United Kingdom)

The invention relates to a preparation method for quizalofop-p-ethyl, in particular to a method which uses p-hydroxybenzaldehyde to replace the raw material hydroquinone used in the traditional technology and react with S (-)-N-tosyl ethyl lactate to prepare R (+)-2-(p-oxy) propionate which is then reacted with 2,6- dichloro-quinoxaline to prepare high-purity quizalofop-p-ethyl through condensation.

YUNSHENG MA; QINGLING SHI; QIYAN FAN; WENLEI WU; YAOGUANG ZHENG

356

Biofiltration of toluene vapors in a carbon-medium biofilter  

Energy Technology Data Exchange (ETDEWEB)

Treatment of toluene vapors in a biofilter with a packed bed of activated carbon pellets was tested. The flowrate was 0.14 m{sup 3}/min, the volume of the bed was 0.25 m{sup 3}, and the bed depth was 1 m. The reactor was capable of removing 70% of the toluene at an input concentration of 2,700 {micro}g/L with an empty bed detection time of 1.8 min. Total removal was 64 g/m{sup 3}/h. Organic carbon removed from the air in a biofilter may be oxidized or incorporated into the biomass. Measurements of heat production and carbon dioxide production indicated, respectively, that 29% or 38% of the removed toluene was oxidized, while the remainder, 62% to 71%, was incorporated into biomass by cell synthesis. The rapid growth of the biomass indicates clogging may occur in biofilters operated at these rates.

Medina, V.F. [RMT Inc., Waukesha, WI (United States); Devinny, J.S. [Univ. of Southern California, Los Angeles, CA (United States). Environmental Engineering Program; Ramaratnam, M. [Westates Carbon, Los Angeles, CA (United States)

1995-12-31

357

Silica encapsulation of toluene soluble quantum dots with high photostability.  

UK PubMed Central (United Kingdom)

We report the silica encapsulation of toluene soluble single quantum dots (QDs) with various silica layer thicknesses. The photoluminescence of silica-encapsulated QD showed a blue shift as the silica layer increased. Although the measured decay lifetime and the quantum yields of the silica-encapsulated QDs decreased as the SiO2 layer increased, the silica-encapsulated QDs showed good photostability for certain silica layer thicknesses. Furthermore, photoblinking, the characteristic optical property of single QD, did not change after silica encapsulation. Silica encapsulation of toluene soluble QDs offers great potential for advanced optical applications.

Isnaeni; Jin LH; Cho YH

2013-04-01

358

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] using gas-liquid chromatography  

International Nuclear Information System (INIS)

The activity coefficients at infinite dilution, ?i?, for both polar and non-polar solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] have been determined by gas-liquid chromatography at the temperatures from (303 to 343) K. The partial molar excess enthalpies at infinite dilution HiE,? of the solutes in the ionic liquid were also calculated from the temperature dependence of the ?i? values. The selectivity for the hexane/benzene and cyclohexane/benzene separation problems was calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literature.

2010-01-01

359

Learning impairments following postnatal exposure to benzene.  

Science.gov (United States)

Two groups of male hooded rats of the Sprague-Dawley strain were administered 550 mg/kg of benzene in corn oil or pure corn oil on Days 9, 11, and 13 postpartum. When tested on problems of the Hebb-Williams closed-field maze-learning task, the rats previously exposed to benzene manifest significantly impaired learning ability when compared to control rats in the total number of error zones entered over the 12 test problems. No significant differences were found in food consumption, water consumption, or weight gain. Moreover, none of the overt manifestations characteristic of acute or chronic benzene exposure were observed. Learning deficits were exhibited at levels of exposure previously considered subtoxic. PMID:6664789

Geist, C R; Drew, K L; Schoenheit, C M; Praed, J E

1983-12-01

360

Learning impairments following postnatal exposure to benzene.  

UK PubMed Central (United Kingdom)

Two groups of male hooded rats of the Sprague-Dawley strain were administered 550 mg/kg of benzene in corn oil or pure corn oil on Days 9, 11, and 13 postpartum. When tested on problems of the Hebb-Williams closed-field maze-learning task, the rats previously exposed to benzene manifest significantly impaired learning ability when compared to control rats in the total number of error zones entered over the 12 test problems. No significant differences were found in food consumption, water consumption, or weight gain. Moreover, none of the overt manifestations characteristic of acute or chronic benzene exposure were observed. Learning deficits were exhibited at levels of exposure previously considered subtoxic.

Geist CR; Drew KL; Schoenheit CM; Praed JE

1983-12-01

 
 
 
 
361

SYNCHROTRON X-RAY MICROTOMOGRAPHY, ELECTRON PROBE MICROANALYSIS, AND NMR OF TOLUENE WASTE IN CEMENT  

International Nuclear Information System (INIS)

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures, prepared with 1.22 to 3.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles, with diameters ranging from 20 to 250 microm; a search with EPMA for vesicles in the range of 1-20 microm proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Since the cements were cured in sealed bottles, the larger portion of toluene must be dispersed within the cement matrix. Evidence for toluene in the cement matrix comes from 29Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also, 2H NMR of d8-toluene/cement samples shows high mobility for all, toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt%, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating from the cement paste and forming vesicular structures that are preserved in the cured cement. Furthermore, at loadings above 3 wt%, the abundance of vesicles formed during toluene/cement paste mixing leads to macroscopic phase separation (most toluene floats to the surface of the cement paste).

1999-01-01

362

SYNCHROTRON X-RAY MICROTOMOGRAPHY, ELECTRON PROBE MICROANALYSIS, AND NMR OF TOLUENE WASTE IN CEMENT.  

Energy Technology Data Exchange (ETDEWEB)

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures, prepared with 1.22 to 3.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles, with diameters ranging from 20 to 250 {micro}m; a search with EPMA for vesicles in the range of 1-20 {micro}m proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Since the cements were cured in sealed bottles, the larger portion of toluene must be dispersed within the cement matrix. Evidence for toluene in the cement matrix comes from {sup 29}Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also, {sup 2}H NMR of d{sub 8}-toluene/cement samples shows high mobility for all, toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt%, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating from the cement paste and forming vesicular structures that are preserved in the cured cement. Furthermore, at loadings above 3 wt%, the abundance of vesicles formed during toluene/cement paste mixing leads to macroscopic phase separation (most toluene floats to the surface of the cement paste).

BUTLER,L.G.

1999-07-22

363

2-Phen-oxy-ethyl benzoate.  

UK PubMed Central (United Kingdom)

In the title compound, C15H14O3, the dihedral angle between the benzene rings is 75.85?(7)°. In the crystal, centrosymmetrically related mol-ecules are weakly associated through pairs of inter-actions between a benzene ring and an O atom of the ester group [ring centroid?O = 3.952?(7)?Å], and through pairs of inter-actions between the other benzene ring and an O atom of the phen-oxy group [ring centroid?O = 3.912?(7)?Å], giving chains extending along [110].

Al-Noaimi M; Warad I; Haddad SF; Husein A; Shareiah R

2013-05-01

364

A method for producing high octane benzene  

Energy Technology Data Exchange (ETDEWEB)

The method for producing high octane benzene, which involves catalytically reforming straight-run benzene fractions, performed in the presence of Pt/A1/sub 2/O/sub 3/ catalyst, and which includes rectifying the fluid reformation products before the final stage, producing the primary and settling fractions, injecting the settling fraction for the last reforming stage and mixing the fraction which has an initial boiling point of 85-104 degrees in order to improve the quality of the target product.

Tanatarov, M.A.; Akhmetov, A.F.; Kiladze, G.K.

1982-01-01

365

Benzene generation from phenylborate decomposition in saltstone  

Energy Technology Data Exchange (ETDEWEB)

High Level Waste Engineering requested SRTC to determine the effect of tetraphenylborate (TPB), triphenylboron (3PB), diphenylborine acid (2PB), and phenylboronic acid (1PB) on the Saltstone process. A previous SRTC report documented benzene evolution from phenylborate decomposition over 91 days, 28 day toxic characteristic leaching procedure (TCLP) results and interactions between phenylborates and components in the saltstone dry chemicals. The ITP Flowsheet team asked SRTC to continue to measure benzene evolution from saltstone samples prepared with 3PB and 2PB. This report documents that work.

Poirier, M.R.

2000-04-19

366

A simple HPLC method to determine urinary phenylmercapturic acid and its application to gasoline station attendants to biomonitor occupational exposure to benzene at less than 1 ppm.  

UK PubMed Central (United Kingdom)

The objective of this study was to establish a hand-saving method to measure phenylmercapturic acid (PMA) and to examine urinary PMA as a marker of occupational exposure to benzene at levels less than 1 ppm. A simple HPLC method was developed to analyse PMA by monitoring absorption at 195 nm of the ef? uent from an ODS-3 column with acetonitrile-methanol-perchloric acid-water as a mobile phase. The detection limit of the method was 0.2 ?g l(-1) with sufficient reproducibility. The method was applied to end-of-shift urine samples from 70 gasoline station attendants exposed to up to 107 ppb benzene, and 20 non-exposed controls of both sexes. Time-weighted average (TWA) exposure to benzene was measured by diffusive sampling. A regression analysis was applied to examine the quantitative relationship between the intensity of exposure to benzene and PMA in the end-of-shift urine samples. Multiple regression analysis showed no effects of age, sex, smoking and co-exposure to toluene and xylenes on urinary PMA. There was a linear relationship between TWA benzene exposure and urinary PMA (r = 0.60-0.67, P < 0.01). Background PMA in urine of the non-exposed controls was low and scattering of PMA around the regression line was narrow so that those with 20 ppb benzene exposure can be separated from the non-exposed by urinalysis for PMA. Thus, urinary PMA is sensitive enough for biological exposure monitoring of those exposed to less than 1 ppm benzene.

Inoue O; Kanno E; Yusa T; Kakizaki M; Watanabe T; Higashikawa K; Ikeda M

2001-01-01

367

A simple HPLC method to determine urinary phenylmercapturic acid and its application to gasoline station attendants to biomonitor occupational exposure to benzene at less than 1 ppm.  

Science.gov (United States)

The objective of this study was to establish a hand-saving method to measure phenylmercapturic acid (PMA) and to examine urinary PMA as a marker of occupational exposure to benzene at levels less than 1 ppm. A simple HPLC method was developed to analyse PMA by monitoring absorption at 195 nm of the ef? uent from an ODS-3 column with acetonitrile-methanol-perchloric acid-water as a mobile phase. The detection limit of the method was 0.2 ?g l(-1) with sufficient reproducibility. The method was applied to end-of-shift urine samples from 70 gasoline station attendants exposed to up to 107 ppb benzene, and 20 non-exposed controls of both sexes. Time-weighted average (TWA) exposure to benzene was measured by diffusive sampling. A regression analysis was applied to examine the quantitative relationship between the intensity of exposure to benzene and PMA in the end-of-shift urine samples. Multiple regression analysis showed no effects of age, sex, smoking and co-exposure to toluene and xylenes on urinary PMA. There was a linear relationship between TWA benzene exposure and urinary PMA (r = 0.60-0.67, P < 0.01). Background PMA in urine of the non-exposed controls was low and scattering of PMA around the regression line was narrow so that those with 20 ppb benzene exposure can be separated from the non-exposed by urinalysis for PMA. Thus, urinary PMA is sensitive enough for biological exposure monitoring of those exposed to less than 1 ppm benzene. PMID:23886275

Inoue, O; Kanno, E; Yusa, T; Kakizaki, M; Watanabe, T; Higashikawa, K; Ikeda, M

2001-01-01

368

Formation of alkylaromatic hydrocarbons with interaction between paraffins and benzene in an H-mordenite  

Energy Technology Data Exchange (ETDEWEB)

Alkylation of benzene by products of transformation of n-pentane and n-hexane in dealuminated H-mordenite (SiO2 to A12O3 of 80) in a medium of hydrogen at a pressure of 3.5 megapascals, a temperature of 300 to 380C in a through type installation is studied. The composition of the alkylaromatic hydrocarbons (UV), formed with interaction between n-pentane and n-hexane and benzene in a high silicon content H-mordenite is studied at a temperature of 300 to 380C and a pressure of 3.5 megapascals. It is established that with a minimal depth of alkylation, the primary formation of ethylbenzene and o-xylene is observed. Toluene and m-xylene and n-xylene are formed as a result of secondary reactions. A mechanism is proposed for disproportionation of the C5H6 paraffins in zeolites with basic formation of the corresponding C3 to C4 and C4 to C5 products, which provides for a stage of intermolecular transfer of the C2 fragments.

Kogan, S.B.; Bursian, N.R.; Karagan, V.K.

1984-01-01

369

Zeolites as catalysts in organic reactions: condensation of aldehydes with benzene derivatives  

Energy Technology Data Exchange (ETDEWEB)

Reactions of four aldehydes with five aromatic compounds have been carried out on a series of USY zeolites with unit cell size in the 24.56 to 24.25-{angstrom} range. Conversion decreased in the order formaldehyde > benzaldehyde > acetaldehyde > propionaldehyde and also in the series anisole > toluene > benzene > chlorobenzene. For aliphatic aldehydes a mixture of ortho-ortho, ortho-para, and para-para diarylmethanes was obtained. USY zeolites show a higher para-directing selectivity than AlCl{sub 3}. Benzaldehyde reacted with benzene derivatives to afford mixtures of diaryl- and triarylmethanes. Formation of ditolyl- and dianisylmethanes in the corresponding reactions indicated that bulky triarylmethanes, once formed inside the crystalline framework, have strong diffusional limitations to get out of the zeolite cavities and can undergo subsequent protolytic cleavage. A decrease in the activity of the zeolite to catalyze hydride transfer reactions lead to a decrease on the diphenylmethane yield. Finally, diphenylmethane appears as a primary product indicating that a series of consecutive reactions such as the formation of diarylcarbinols followed by protonation, water elimination, and hydride abstraction are taking place inside the pores of the zeolite before the real primary product comes out from the zeolite.

Climent, M.J.; Corma, A.; Garcia, H.; Primo, J. (Universidad Politecnica de Valencia (Spain))

1991-07-01

370

Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research.  

Science.gov (United States)

In 1977 Maltoni and Scarnato were the first to demonstrate that benzene is an experimental carcinogen in rats. With that and other experiments, Maltoni et al have shown that benzene administered by ingestion (stomach tube) or inhalation is a multipotential carcinogen in rats (of two different strains) and mice and produces a variety of tumors, namely: Zymbal gland carcinomas, oral and nasal cavity carcinomas, skin carcinomas, acanthomas, dysplasias and carcinomas of forestomach, mammary malignant tumors, hepatomas, liver angiosarcomas, hemolymphoreticular neoplasias, and pulmonary tumors. The incidence of Zymbal gland carcinomas and carcinomas of the oral and nasal cavities is affected by the length of treatment by inhalation and by the age of animals. However, the available epidemiological and experimental data at present do not provide precise information on the risk of doses around or below 10 ppm. Long-term carcinogenicity bioassays at 50, 25, 10, 5 and 1 ppm may be helpful for scientific risk assessment. In addition, these experiments have shown that toluene, xylene, and ethylbenzene, at high concentrations, cause an increase in the number of total malignant tumors. PMID:4003403

Maltoni, C; Conti, B; Cotti, G; Belpoggi, F

1985-01-01

371

Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research.  

UK PubMed Central (United Kingdom)

In 1977 Maltoni and Scarnato were the first to demonstrate that benzene is an experimental carcinogen in rats. With that and other experiments, Maltoni et al have shown that benzene administered by ingestion (stomach tube) or inhalation is a multipotential carcinogen in rats (of two different strains) and mice and produces a variety of tumors, namely: Zymbal gland carcinomas, oral and nasal cavity carcinomas, skin carcinomas, acanthomas, dysplasias and carcinomas of forestomach, mammary malignant tumors, hepatomas, liver angiosarcomas, hemolymphoreticular neoplasias, and pulmonary tumors. The incidence of Zymbal gland carcinomas and carcinomas of the oral and nasal cavities is affected by the length of treatment by inhalation and by the age of animals. However, the available epidemiological and experimental data at present do not provide precise information on the risk of doses around or below 10 ppm. Long-term carcinogenicity bioassays at 50, 25, 10, 5 and 1 ppm may be helpful for scientific risk assessment. In addition, these experiments have shown that toluene, xylene, and ethylbenzene, at high concentrations, cause an increase in the number of total malignant tumors.

Maltoni C; Conti B; Cotti G; Belpoggi F

1985-01-01

372

A field campaign for measurement of benzene in urban area of Venice  

International Nuclear Information System (INIS)

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.

1996-01-01

373

3-ethyl 5-methyl(+/-)2-[2-(N-tritylamino)ethoxymethyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-6-methyl-3,5-pyridinedicarboxylate  

UK PubMed Central (United Kingdom)

There is disclosed a process for the preparation of 3-ethyl 5-methyl (+/-) 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridine-dicarboxylate monobenzenesulphonate (amlodipine benzenesulphonate) of formula wherein 3-ethyl 5-methyl (+/-) 2-[2-(N-tritylamino)-ethoxymethyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate is reacted with benzenesulphonic acid in a methanolic or an aqueous methanolic medium at a temperature from 20 DEG C. to the reflux temperature and the title compound is isolated and purified. Amlodipine benzene sulphonate is a valuable anti-ischaemic and anti-hypertensive agent.

FURLAN BORUT; COPAR ANTON; JERIHA ALENKA

374

Microplants for ethyl alcohol production  

Energy Technology Data Exchange (ETDEWEB)

This report deals with the Design of Microplants for Ethyl Alcohol Production, as a part of the Energy for Rural Development concept suggested and supported by the Sao Paulo State Government, aimed at finding a new solution for the problem of energy independence for small rural enterprises and communities remote from the country's more developed centers. In order to arrive at a realistic concept for these Microplants with regard to their technical and economic feasibility and especially to their initial cost, original solutions were developed for several items of equipment necessary to the process. Specially notable among these are a wooden fractionating column packed with bamboo Raschig rings and a steel - reinforced cement-mortar tank for storing the final product.

Villen, R.A.

1981-01-01

375

Characterization of ethyl cellulose polymer.  

UK PubMed Central (United Kingdom)

Ethyl cellulose (EC) polymer was characterized for its property before considering the interactions with the plasicizer. Ethocel Std.10 FP Premium from Dow chemical company USA was tested for its solubility, morphology and thermal properties. Seven percentage of EC solution in ethanol was found to be the right viscosity used to prepare the film. The EC polymer and EC film without any plasticizers showed almost identical thermal behavior, but in X-ray diffraction showed different arrangements of crystallites and amorphous region. Dynamic mechanical analysis of film showed that without a plasticizer, EC film was not flexible and had very low elongation with high applied force. The aim of the work was to avoid using the commercially available EC dispersions Surelease® and Aquacoat®; both already have additives on it. Instead, Ethocel EC polymer (powder) was characterized in our laboratory in order to find out the properties of polymer before considering the interactions of the polymer with various plasticizers.

Mahnaj T; Ahmed SU; Plakogiannis FM

2013-09-01

376

Kinetics of toluene hydrogenation on a supported Ni catalyst  

Energy Technology Data Exchange (ETDEWEB)

The gas-phase hydrogenation of toluene to methylcyclohexane was studied on a noncommercial supported nickel catalyst. The reaction kinetics were investigated in a differential reactor operating at atmospheric pressure and temperatures between 120 and 200 C. The results revealed that the hydrogenation kinetics is of the order 0.5-2 with respect to hydrogen and that the reaction order increases with temperature. The reaction order with respect to toluene increases from slightly negative values to zero order over the temperature domain studied. The kinetics was modeled with an empirical power-law rate expression and with two mechanistic rate models. The latter models were based on the assumption of rapid competitive adsorption steps of toluene and hydrogen and rate-determining surface reaction steps involving addition of hydrogen atom pairs to adsorbed toluene and partially hydrogenated intermediate molecules. The surface coverages, the activation energy, and the optimal reaction temperature giving the maximum reaction rate were estimated using parameter values obtained from one of the mechanistic models.

Lindfors, L.P. (Neste Oy, Borga (Finland)); Salmi, T. (Lab. of Industrial Chemistry, Abo (Finland))

1993-01-01

377

Radiation-induced oxidation of toluene, Pt. 1  

International Nuclear Information System (INIS)

[en] Based on detailed analyses of the radiation yields of products formed during the radiation-induced oxidation of toluene, a mechanism is suggested to describe the experimental results. Certain rate constants with respect to radical interaction were calculated resulting in the radiation yields of products formed in these steps. (author)

1982-01-01

378

Reactions of methanol and toluene over molybdenum zeolites  

International Nuclear Information System (INIS)

The catalytic properties of zeolites ZSM-5, mordenite and Y either ion exchanged or impregnated with molybdenum for the conversion of methanol and toluene have been investigated. The distribution of products and change in catalytic properties is accounted for in terms of acidity and the location of molybdenum in zeolites

1988-01-01

379

Mass accommodation of aniline, phenol and toluene on aqueous droplets  

Energy Technology Data Exchange (ETDEWEB)

This report describes measurements of mass accommodation coefficients at a temperature of 283k for the volatile organic compounds aniline, phenol, and toluene using the droplet train method. Laser induced fluoresecence was used as a detection method for the trace molecules.

Heal, M.R.; Pilling, M.J.; Titcombe, P.E. [Univ. of Leeds (United Kingdom)] [and others

1995-11-15

380

Antipyrine clearance during experimental and occupational exposure to toluene  

DEFF Research Database (Denmark)

Exposure to toluene vapour enhances hepatic microsomal enzyme function in animals as assessed by the metabolism of the test drug antipyrine. Thirty six printing trade workers with long term occupational exposure to a mixture of organic solvents and 39 matched controls were randomly allocated into four groups. Eighteen printers and 21 controls were exposed to 100 ppm of toluene during 6.5 hours in an exposure chamber. The remaining 18 printers and 18 controls were exposed to 0 ppm of toluene under similar conditions. The salivary clearance of antipyrine was measured immediately after the stay in the exposure chamber to investigate a possible acute change in liver function and was repeated two weeks later, shortly before the summer vacation. Antipyrine clearance was measured again at the end of the summer vacation-four weeks after exposure. To study a possible effect of chronic exposure on antipyrine clearance 12 printing trade workers with 17 years (median) of occupational exposure to toluene vapour at concentrations of about 100 ppm were investigated before and four weeks after cessation of exposure. No difference in antipyrine clearance was found either within the groups or between the groups at any of the measurements.

DØssing, M; Bælum, Jesper

1983-01-01

 
 
 
 
381

Biofiltration of toluene using wood charcoal as the biofilter media.  

UK PubMed Central (United Kingdom)

A laboratory scale biofilter inoculated with Pseudomonas putida (MTCC 102) was used for degradation of toluene present in air. Wood charcoal was used as the filter media and a layer of glass beads (6mm) was used for improved air distribution. The biofilter was operated continuously for a period of 5months at four different flow rates - 0.06, 0.12, 0.18, and 0.24m(3)h(-1), with inlet concentration of toluene ranging from 0.04 to 4.5gm(-3). Air having toluene vapor was fed to the biofilter at various loadings ranging from 30.6 to 1104.5gm(-3)h(-1). The removal efficiency was obtained in the range of 70-99.5%. The maximum elimination capacity of 872.5gm(-3)h(-1) was observed at the inlet load of 1104.5gm(-3)h(-1). Wood charcoal was found to an effective biofilter media for toluene biodegradation.

Singh K; Singh RS; Rai BN; Upadhyay SN

2010-06-01

382

PHOSPHOLIPIDS OF FIVE PSEUDOMONAD ARCHETYPES FOR DIFFERENT TOLUENE DEGRADATION PATHWAYS  

Science.gov (United States)

Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine phospholipid profiles for five reference pseudomonad strains harboring distinct toluene catabolic pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, B...

383

Reproductive endocrine effects of acute exposure to toluene in men and women  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVES: Despite observation of adverse reproductive effects of toluene, including alterations of serum gonadotropins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) in humans, little is known of the mechanism of toxicity. The hypothesis was tested that toluene acutely supp...

Luderer, U.; Morgan, M. S.; Brodkin, C. A.; Kalman, D. A.; Faustman, E. M.

384

Enhanced visible-light induced degradation of benzene on Mg-ferrite/hematite/PANI nanospheres: in situ FTIR investigation.  

UK PubMed Central (United Kingdom)

The dramatic enhanced visible-light photocatalytic activity of Mg-ferrite/hematite nanospheres photocatalysts on benzene were obtained after hybridized by polyaniline (PANI) using the chemisorption method. The samples were characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra and UV-Vis diffuse reflectance spectroscopy. The enhancement of photocatalytic degradation of benzene under visible-light irradiation was mainly ascribed to the high efficiency of charge separation induced by the hybrid effect of PANI and Mg-ferrite/hematite. By using the in situ FTIR technique, ethyl acetate, carboxylic acid and aldehyde could be regarded as the intermediate products, and CO(2) is determined as the final product during the reaction process.

Shen Y; Zhao Q; Li X; Yuan D; Hou Y; Liu S

2012-11-01

385

Enhanced visible-light induced degradation of benzene on Mg-ferrite/hematite/PANI nanospheres: in situ FTIR investigation.  

Science.gov (United States)

The dramatic enhanced visible-light photocatalytic activity of Mg-ferrite/hematite nanospheres photocatalysts on benzene were obtained after hybridized by polyaniline (PANI) using the chemisorption method. The samples were characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra and UV-Vis diffuse reflectance spectroscopy. The enhancement of photocatalytic degradation of benzene under visible-light irradiation was mainly ascribed to the high efficiency of charge separation induced by the hybrid effect of PANI and Mg-ferrite/hematite. By using the in situ FTIR technique, ethyl acetate, carboxylic acid and aldehyde could be regarded as the intermediate products, and CO(2) is determined as the final product during the reaction process. PMID:23107291

Shen, Yu; Zhao, Qidong; Li, Xinyong; Yuan, Deling; Hou, Yang; Liu, Shaomin

2012-10-11

386

Extraction of toluene from aliphatic compounds using an ionic liquid as solvent: Influence of the alkane on the (liquid + liquid) equilibrium  

International Nuclear Information System (INIS)

Research highlights: ? An ionic liquid was analyzed as solvent for extraction of toluene from alkanes. ? Liquid-liquid equilibrium data were measured at 298.15 K and atmospheric pressure. ? Selectivity and solute distribution ratio were obtained and compared with literature. ? The Othmer-Tobias equation was used to ascertain the experimental LLE data. ? Experimental data were correlated using NRTL and UNIQUAC models. - Abstract: In this paper, the feasibility of using 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid, [EMim][ESO4], as solvent for the extraction of toluene from aliphatic compounds (hexane, heptane, octane, or nonane) was analyzed. (Liquid + liquid) equilibrium (LLE) data for the ternary systems {alkane (1) + toluene (2) + [EMim][ESO4] (3)} were measured at T = 298.15 K and atmospheric pressure. Selectivity and solute distribution ratio were calculated from the experimental LLE data, and the obtained values were compared to those previously reported using other ionic liquids and sulfolane. The degree of consistency of the experimental LLE data was ascertained using the Othmer-Tobias equation. Finally, the experimental LLE data were satisfactorily correlated with NRTL and UNIQUAC models.

2011-01-01

387

Determination of the unburnt benzene in the autovehicular emission  

International Nuclear Information System (INIS)

The exhaust benzene emission from passengers cars has been characterized using a methodology based on deuterated compounds. European vehicles were fueled with a gasoline containing a total benzene concentration (hydrogenated plus deuterated) ranging from 0.98 to 2.75 v/v. Since deuterated benzene at the tail pipe can be present only as unburnt from the fuel, calculating the relative ratio of hydro/deutero compound, the unreacted benzene and that formed in the combustion process can be recognized and the corresponding percentage of unburnt compound qualified. This approach allowed to confirm the benzene formation in the catalytic converter. The experimental data, both for a vehicle equipped with a three way catalytic muffler and for a carburetor car, fit the expected curve describing the percentage of emitted unburnt benzene (considered with respect to the total amount of benzene in the exhaust gas) vs. the benzene content of the gasoline.

1996-01-01

388

Determination of the unburnt benzene in the autovehicular emission  

Energy Technology Data Exchange (ETDEWEB)

The exahaust benzene emission from passengers cars has been characterized using a methodology based on deuterated compounds. European vehicles were fueled with a gasoline containing a total benzene concentration (hydrogenated plus deuterated) ranging from 0.98 to 2.75 v/v. Since deuterated benzene at the tailpipe can be present only as unburnt from the fuel, calculating the relative ratio of hydro/deutero compound, the unreacted benzene and that formed in the combustion process can be recognized and the corresponding percentage of unburnt compound qualified. This apporach allowed to confirm the benzene formation in the catalytic converter. The experimental data, both for a vehicle equipped with a three way catalytic muffler and for a carburetor car, fit the expected curve describing the percentage of emitted unburnt benzene (considered with respect to the total amount of benzene in the exhaust gas) vs. the benzene content of the gasoline.

Latella, A.; Buttini, P. [Eniricerche SpA, Monterotondo (Italy); Corno, C. [Eniricerche SpA, Milan (Italy); Marchesi, G. F. [Euron, San Donato Milanese, Milan (Italy)

1996-06-01

389

Toluene biofiltration by the fungus Scedosporium apiospermum TB1.  

UK PubMed Central (United Kingdom)

The performance of biofilters inoculated with the fungus Scedosporium apiospermum was evaluated. This fungus was isolated from a biofilter which operated with toluene for more than 6 months. The experiments were performed in a 2.9 L reactor packed with vermiculite or with vermiculite-granular activated carbon as packing material. The initial moisture content of the support and the inlet concentration of toluene were 70% and 6 g/m3, respectively. As the pressure drop increased from 5-40 mm H2O a strong initial growth was observed. Stable operation was maintained for 20 days with a moisture content of 55% and a biomass of 33 mg biomass/g dry support. These conditions were achieved with intermittent addition of culture medium, which permitted a stable elimination capacity (EC) of 100 g/m3(reactor)h without clogging. Pressure drop across the bed and CO2 production were related to toluene elimination. Measurement of toluene, at different levels of the biofilter, showed that the system attained higher local EC (200 g/m3(r)h) at the reactor outlet. These conditions were related to local humidity conditions. When the mineral medium was added periodically before the EC decreases, EC of approximately 258 g/m3(r)h were maintained with removal efficiencies of 98%. Under these conditions the average moisture content was 60% and 41 mg biomass/g dry support was produced. No sporulation was observed. Evaluation of bacterial content and activities showed that the toluene elimination was only due to S. apiospermum catabolism.

García-Peña EI; Hernández S; Favela-Torres E; Auria R; Revah S

2001-01-01

390

Excited-state decay of hydrocarbon radicals, investigated by femtosecond time-resolved photoionization: ethyl, propargyl, and benzyl.  

UK PubMed Central (United Kingdom)

The excited state decay of the hydrocarbon radicals ethyl, C(2)H(5); propargyl, C(3)H(3); and benzyl, C(7)H(7) was investigated by femtosecond time-resolved photoionization. Radicals were generated by flash pyrolysis of n-propyl nitrite, propargyl bromide, and toluene, respectively. It is shown that the 2 (2)A(') (3s) Rydberg state of ethyl excited at 250 nm decays with a time constant of 20 fs. No residual signal was observed at longer delay times. For the 3 (2)B(1) state of propargyl excited at 255 nm a slower decay with a time constant 50+/-10 fs was determined. The 4 (2)B(2) state of benzyl excited at 255 nm decays within 150+/-30 fs.

Zierhut M; Noller B; Schultz T; Fischer I

2005-03-01

391

Growth of the fungus Cladosporium sphaerospermum with toluene as the sole carbon and energy source  

Energy Technology Data Exchange (ETDEWEB)

The fungus Cladosporium sphaerospermum was isolated from a biofilter used for the removal of toluene from waste gases. This is the first report describing growth of a eukaryotic organism with toluene as the sole source of carbon and energy. The oxygen consumption rates, as well as the measured enzyme activities, of toluene-grown C. sphaerospermum indicate that toluene is degraded by an initial attack on the methyl group. 32 refs., 2 figs., 2 tabs.

Weber, F.J.; Hage, K.C.; De Bont, J.A.M. [Wageningen Agricultural Univ. (Netherlands)

1995-10-01

392

On the mechanism of the dehydroaromatization of hexane to benzene by an iridium pincer catalyst.  

UK PubMed Central (United Kingdom)

The developments in the area of transition-metal pincer complexes have opened up new avenues for conversion of saturated hydrocarbons to more useful aromatic compounds under homogeneous reaction conditions. In the backdrop of an interesting series of conversions of unbranched alkanes to benzene, toluene, and xylene (known as the BTX family aromatics) reported by Goldman and co-workers (Nature Chem. 2011, 3, 167), we herein present a comprehensive mechanistic picture obtained by using density functional computations. The reaction involves an iridium-PCP-pincer-catalyzed dehydroaromatization of hexane to benzene (in which PCP=?(3) -C6 H3 (iPrP)2 -1,3) by using tert-butylethylene (TBE) as a sacrificial acceptor. The most energetically preferred pathway for a sequence of dehydrogenations is identified to begin with a terminal C?H bond activation of n-hexane leading to the formation of hex-1-ene. Although the initial dehydrogenation of n-hexane was found to be endergonic, the accompanying exoergic hydrogenation of TBE to tert-butylethane (TBA) compensates the energetics to keep the catalytic cycle efficient. Subsequent dehydrogenations provide a hexa-1,3-diene and then a hexa-1,3,5-triene. The pincer bound triene is identified to undergo cyclization to furnish cyclohexadiene. Eventually, dehydrogenation of cyclohexa-1,3-diene offers benzene. In the most preferred pathway, the Gibbs free energy barrier for cyclization leading to the formation of cyclohexa-1,3-diene is found to exhibit the highest barrier (21.7?kcal?mol(-1) ).

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