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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  

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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 toluene: methanol (5:1), (3:1), (1:1), (1:3) and (1:5) molar ratios have been applied. It found that 1:1 most suitable molar ratio for side chain alkylation of toluene. The mixture was pumped into t...

Abdallah, Mohamed Hassen Ahmed

2011-01-01

3

Formation mechanisms for benzene and toluene during sewage sludge incineration  

Energy Technology Data Exchange (ETDEWEB)

Air-dried sewage sludge was combusted in a laboratory furnace at different temperatures and percents stoichiometric oxygen. The concentrations of benzene and toluene in the effluent gas were determined. The quantity of benzene and toluene increased with decreasing oxygen levels. Increasing the temperature from 750 to 1000/sup 0/C caused an increase in the concentration of benzene. The temperature of maximum toluene production was 850/sup 0/C. Above that temperature toluene was thermally unstable. The fatty acids in the grease and oil fraction of the sludge were found to be the source of the benzene and toluene. Reaction mechanisms leading from the fatty acids to benzene an toluene were proposed.

Burns, L.R.

1986-01-01

4

Transformation of toluene and benzene by mixed methanogenic cultures.  

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The aromatic hydrocarbons toluene and benzene were anaerobically transformed by mixed methanogenic cultures derived from ferulic acid-degrading sewage sludge enrichments. In most experiments, toluene or benzene was the only semicontinuously supplied carbon and energy source in the defined mineral medium. No exogenous electron acceptors other than CO2 were present. The cultures were fed 1.5 to 30 mM unlabeled or 14C-labeled aromatic substrates (ring-labeled toluene and benzene or methyl-labele...

Grbic?-galic?, D.; Vogel, T. M.

1987-01-01

5

Study of benzene and toluene adsorption on granular activated carbon  

Energy Technology Data Exchange (ETDEWEB)

Benzene and toluene are among the organic compounds designated by EPA as priority pollutants because of their toxicity to man and the environment. Activated carbon has been used to remove organic compounds from waters for many years. However, little or no information is available in the literature on the removal of specific organic compounds by activated carbon. Therefore, this study was undertaken to investigate the adsorption of benzene and toluene from aqueous solutions onto granular activated carbon. Calgon Filtrasorb 400 carbon was used as the adsorbent. The samples were analyzed on a Perkin-Elmer Sigma 3B gas chromatograph with flame ionization equipped with an HS-6 Head Space Sampler. The data fit the Freundlich isotherm model well with a high correlation coefficient. The pH of the test solutions at 3, 6.5, and 9 shows no effect on benzene adsorption and slight effect on toluene adsorption. The study shows that the amount of benzene or toluene adsorbed increases with increasing initial concentrations. Competitive adsorption of benzene and toluene when present in aqueous mixtures together and with chloroform, acetone, and tert-butanol, shows a significant reduction in benzene adsorption and a little effect on toluene adsorption. Also this study shows that ozone oxidizes benzene and toluene more effectively at pH 3 and 6.5 than at pH 9. The benzene adsorption is reduced somewhat in the presence of ozone byproducts of benzene. However, the toluene adsorption is enhanced in the presence of toluene ozonation byproducts.

Samaneh, T.S.A.

1981-01-01

6

Metabolism of Benzene, Toluene, and Xylene Hydrocarbons in Soil†  

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Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted us to investigate the metabolism of 14C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically replenished any O2 consumed. The decrease in solvent vapors and the produ...

1998-01-01

7

Radiolysis of cyclic polyether solutions in benzene and toluene  

International Nuclear Information System (INIS)

Effect of a number of macrocyclic polyethers on dimer product formation during liquid phase benzene and toluene ?-radiolysis ("6"0Co, dose rates 5.0-5.4 Gy/s) is investigated. It is stated that radiation-chemical yield of diphenyl and phenyl cyclohexadienes is considerably decreased during benzene radiolysis in the presence of additions while during toluene radiolysis some increase in dimer yield is observed (excluding dibenzyl in case of dibenzo-24-crown-8 addtion). Possible mechanisms of crown ethers effect on radiolysis of aromatic hydrocarbons are suggested

1986-01-01

8

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

9

Cation transport in gaseous, critical, and liquid benzene and toluene  

Science.gov (United States)

The mobilities ?+ of cations in the fluids of benzene and toluene are 200-3000 fold lower than those of electrons. However, the variations of the cation mobilities with density and temperature are qualitatively similar to those of electrons, to an unexpected degree. In the liquid phase under its vapor pressure at T/TcWalden's rule (?+~?-x, x=1.0), but in toluene it does not (x=1.1). The ratio of the diffusion coefficients (cation/solvent molecule) is equal to about 0.25 in toluene and 0.50 in benzene. Near the critical point there is a slight maximum in ?+. The maximum is more marked in the density normalized mobility ?+n; it occurs at n/nc=2.0 in benzene and 1.6 in toluene. The mobilities in the critical fluids are 2.76×10-3 and 2.50×10-3 cm2/V s in benzene and toluene, respectively. In the low density gases the ion scattering cross sections, taken to have the form ?v=A? v-?, display ?=1.4 for benzene and 1.5 for toluene. The cross sections, appropriately averaged over the Maxwellian distribution of velocities, have magnitudes similar to those expected from scattering by the r-4 polarization potential, but have a greater than expected value of ?. The average ion scattering cross sections are about eightfold greater than the corresponding electron scattering cross sections. The value of ?+n in the coexistence vapor is 6.3×1018 molecule/cm V s in benzene up to n/nc=1.0, and is 6.0×1018 in toluene up to n/nc=0.15. At higher densities in the latter ?+n decreases gently, reaching (?+n)min=4.4×1018 at n/nc=0.9. The temperature coefficient of ?+ at constant n increases with n up to nc, near the coexistence curve. The increased temperature coefficient is attributed to clustering, but the clusters are small.

Huang, Sam S.-S.; Freeman, Gordon R.

1980-02-01

10

Measurements of benzene, toluene and xylenes in urban air  

Science.gov (United States)

Results from measurements of benzene, toluene and xylenes in the city centre of Oslo are presented. The samples were collected in March and August/September 1980 at two of the stations used in an air pollution monitoring program. One was in a street canyon station and the other was a reference station. The sampling equipment was two charcoal filters in series, placed in a filter holder with a disk of glass fibre prefilter in front. Analysis was by high resolution gas chromatography. The single measured separate values of these aromatics ranged from 1 to 210?m -3. Benzene concentrations especially ranged from 4 to 114 ?g m -3. The concentrations of benzene and toluene seemed to be higher in August/September than in March, while the concentrations of the xylenes seemed to be about the same. The variations in concentrations of the aromatics follow each other closely in both measuring periods which indicates that all components are emitted from the same sources and are dispersed in the same way. Correlation between benzene and CO and between benzene and ambient temperature are discussed.

Wathne, Bente M.

11

Reductive dehalogenation of chlorinated benzenes and toluenes under methanogenic conditions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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)-->1,2,3-TCB + 1,2,4-TCB-->1,2-dichlorobenzene (DCB) + 1...

1993-01-01

12

Comparison of measurement methods for benzene and toluene  

Science.gov (United States)

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

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

13

Gas yields in the radiolysis of benzene, toluene styrene and their mixtures  

International Nuclear Information System (INIS)

The G-values of H_2, CH_4 and C_2H_2 are determined in toluene-benzene and toluene-styrene mixtures. From the results it is concluded that CH_3 radicals generated from toluene are captured both by benzene and styrene but, as expected, the reaction is much more efficient with styrene. A radical precursor of C_2H_2 which could be hexatrienyl is efficiently scavenged by toluene, presumably by H atom transfer. This reaction also accounts for the very low yield of C_2H_2 in pure toluene. (author)

1982-01-01

14

Modeling Biodegradation Kinetics on Benzene and Toluene and Their Mixture  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this work was to model the biodegradation kinetics of toxic compounds toluene and benzene as pure substrates and in a mixture. As a control, Monod and Andrews models were used. To predict substrates interactions, more sophisticated models of inhibition and competition, and SKIP (sum kinetics interactions parameters model were applied. The models evaluation was performed based on the experimental data from Pseudomonas putida F1 activities published in the literature. In parameter identification procedure, the global method of particle swarm optimization (PSO was applied. The simulation results show that the better description of the biodegradation process of pure toxic substrate can be achieved by Andrews' model. The biodegradation process of a mixture of toxic substrates is modeled the best when modified competitive inhibition and SKIP models are used. The developed software can be used as a toolbox of a kinetics model catalogue of industrial wastewater treatment for process design and optimization.

Aparecido N. Módenes

2007-10-01

15

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

16

Study of thermodesorption of ethyl benzene from zeolite catalysts  

International Nuclear Information System (INIS)

Thermodesorption of ethyl benzene from different cation and decationized zeolite forms of NaX and NaY types including BeY, NdY, CeY has been investigated by the chromatography method. The thermodesorption spectrum of all the specimens investigated consists of a single peak. Na cation exchange for polyvalent cations results in shifting temperature of thermodesorption type maximum to the low-temperature region. Calculated are diffusion activation energy, pre-exponential factors, effective diffusion coefficients. Dependences of the reaction rate of oxidizing dehydrogenation of ethyl benzene, effective diffusion coefficient on the value of electrostatic cation potential in the Y zeolite go through the NdY maximum

1978-01-01

17

Secondary organic aerosol formation from m-xylene, toluene, and benzene  

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Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the SOA yields (d...

2007-01-01

18

Secondary organic aerosol formation from m-xylene, toluene, and benzene  

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Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the SOA yields (d...

2007-01-01

19

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

20

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.

2012-05-01

 
 
 
 
21

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

Directory of Open Access Journals (Sweden)

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

Seik Weng Ng

2009-02-01

22

Incorporation of oxygen from water into toluene and benzene during anaerobic fermentative transformation  

International Nuclear Information System (INIS)

Toluene and benzene were anaerobically transformed and eventually mineralized in mixed methanogenic cultures. However, the source of oxygen for the initial oxidation step had been unknown, owing to the presence of both methanol and water. No exogenous electron acceptors other than carbon dioxide, toluene, and benzene were present in the defined mineral medium. Through the use of "1"8O-labeled water, the oxygen incorporated into the monoaromatic compounds was shown to come from water. The cresol from the toluene and the phenol from the benzene contain up to 8% "1"8O label after incubation in 9% "1"8O-labeled medium. Gas chromatography-mass spectrometry was used to detect the "1"8O-labeled aromatic metabolites

1986-01-01

23

Hematological indices of peripheral blood in workers occupationally exposed to benzene, toluene and xylene  

Energy Technology Data Exchange (ETDEWEB)

In 106 workers occupationally exposed to benzene, toluene and xylene through 1 to 122 months basic hematological indices of peripheral blood were evaluated. The benzene, toluene and xylene concentrations in the air at workplaces were equal to 0-370, 0-580 and 0-506 mg/m3, respectively. The workers were subdivided into three subgroups according to the service time corresponding to 1-29, 31-54 and 55-122 months. The first hematological changes noted in the workers studied consisted of diminishing the mean corpuscular hemoglobin and the mean corpuscular hemoglobin concentration in erythrocytes. Increased numbers of reticulocytes, lowered total count of leukocytes due to decreased numbers of T and ''non-T, non-B'' cells as well as increased numbers of monocytes were other signs of exposure investigated. Increased numbers of reticulocytes were noted in all workers independently of service time whereas other hematological alterations presented above were marked only in the subgroup of workers exposed to benzene, toluene and xylene through 55 to 122 months. It was stated that the T cell count decreased gradually in relationship with an extent of exposure time (negative correlation). Since laboratory examinations serving the evaluation of health state of workers exposed are only few it was postulated that the E rosette test may be of practical use for monitoring the toxic effect of benzene, toluene and xylene on the lymphocyte system.

Moszczynski, P.; Lisiewicz, J.

1983-12-01

24

Hematological indices of peripheral blood in workers occupationally exposed to benzene, toluene and xylene  

Energy Technology Data Exchange (ETDEWEB)

In 106 workers occupationally exposed to benzene, toluene and xylene through 1 to 122 months basic hematological indices of peripheral blood were evaluated. The benzene, toluene and xylene concentrations in the air at workplaces were equal to 0-370, 0-580 and 0-506 mg/m/sup 3/, respectively. The workers were subdivided into three subgroups according to the service time corresponding to 1-29, 31-54 and 55-122 months. The first hematological changes noted in the workers studied consisted of diminishing the mean corpuscular hemoglobin and the mean corpuscular hemoglobin concentration in erythrocytes. Increased numbers of reticulocytes, lowered total count of leukocytes due to decreased numbers of T and ''non-T, non-B'' cells as well as increased numbers of monocytes were other signs of exposure investigated. Increased numbers of reticulocytes were noted in all workers independently of service time whereas other hematological alterations presented above were marked only in the subgroup of workers exposed to benzene, toluene and xylene through 55 to 122 months. It was stated that the T cell count decreased gradually in relationship with an extent of exposure time. Since laboratory examinations serving the evaluation of health state of workers exposed are only few it was postulated that the E rosette test may be of practical use for monitoring the toxic effect of benzene, toluene and xylene on the lymphocyte system.

Moszczcynski, P.; Lisiewicz, J.

1983-01-01

25

Photoacoustic spectroscopy-based detector for measuring benzene and toluene concentration in gas and liquid samples  

International Nuclear Information System (INIS)

Here we present a novel instrument for on-line, automatic measurement of benzene and toluene concentration in gas and liquid samples produced in the natural gas industry. Operation of the instrument is based on the collection of analytes on an adsorbent, separation using a chromatographic column and detection by near-infrared diode laser-based photoacoustic spectroscopy. Sample handling, measurement and data evaluation are carried out fully automatically, using an integrated, programmable electronic unit. The instrument was calibrated in the laboratory for natural gas, nitrogen and liquid glycol samples, and tested under field conditions at a natural gas dehydration unit of the MOL Hungarian Oil and Gas Company. Minimum detectable concentrations (3?m?1) were found to be 2.5 µg l?1 for benzene and 4 µg l?1 for toluene in gas samples, while 1.5 mg l?1 for benzene and 3 mg l?1 for toluene in liquid samples, which is suitable for measuring benzene and toluene concentration in natural gas and glycol samples occurring at natural gas dehydration plants

2011-12-01

26

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

Science.gov (United States)

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

2013-01-01

27

Research on biological effects induced by ?-irradiation combined with benzene, toluene and carbon monoxide inhalation  

International Nuclear Information System (INIS)

Objective: To explore the patterns of biological effects induced by ?-rays irradiation combined with simultaneous inhalation benzene, toluene or carbon monoxide and to analyze their antagonistic,additive or synergistic interaction. Methods: Ninety healthy male rabbits were equally divided into 9 groups. Eight of which were assigned to be test groups according to four-factor-two-dose-level orthogonal layout {L8(27) } program and the other one was the control group. The two dose-levels of these four agents were: the ?-irradiation doses were 0.0075 Gy/d and 0.0375 Gy/d, and the two concentrations of benzene, toluene and carbon monoxide were 40 +-15 and 162 +- 33 mg/m3, 90 +- 30 and 407 +- 68 mg/m3, 93 +- 4 and 278 +- 8 mg/m3, respectively. The animals were exposed to ?-irradiation combined with benzene,toluene or CO vapour 2 h a day and 5 days a week for successive 8 weeks. Variance analysis and comparison between test groups were made for analyzing the test data. Results: (1) It was showed that ?-irradiation, benzene and toluene could all induce chromosome aberrations, SCEs and micronuclei of lymphocytes and chromosome aberrations of bone marrow cells; but no effect could be seen in CO alone treated group. (2) The ratios (?) of biological effects jointly induced by the four agents and the sum of those induced separately by them were 2.16, 1.58, 2.07, 2.67, 1.25 and 1.18 for dicentric + ring,acentric, aberration cells, total aberration, micronuclei and micronucleus cells, respectively,and it was as high as 5.97 for aberrant sperms.The ratios showed that the interactions were synergistic(?>1). However,interactions between ?-rays and benzene was antagonistic for acentric of lymphocytes. (3) The four agents could all obviously cause decrease of weight index of testis, ?-rays,toluene and CO could all markedly reduce the number of sperms and increase the ratio of aberrant sperms. Conclusion: ?-irradiation combined with benzene, toluene and CO inhalation can lead to significant interactions which are mainly synergistic,while CO can cause obvious effects on sex gland when it is combined with ?-rays, benzene and toluene

2000-10-01

28

Biotransformation of benzene and toluene to catechols by phenol hydroxylase from Arthrobacter sp. W1.  

Science.gov (United States)

Phenol hydroxylase gene engineered microorganism (PHIND) was used to synthesize catechols from benzene and toluene by successive hydroxylation reaction. HPLC-MS and (1)H NMR analysis proved that the products of biotransformation were the corresponding catechols via the intermediate production of phenols. It was indicated that the main products of toluene oxidation were o-cresol and p-cresol. 3-Methylcatechol was the predominant product for m-cresol biotransformation. Formation rate of catechol (25 ?M/min/g cell dry weight) was 1.43-fold higher than that of methylcatechols. It was suggested that phenol hydroxylase could be successfully used to transform both benzene and toluene to catechols by successive hydroxylation. PMID:22854893

Ma, Fang; Shi, Sheng-Nan; Sun, Tie-Heng; Li, Ang; Zhou, Ji-Ti; Qu, Yuan-Yuan

2013-06-01

29

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

30

Biotransformation of toluene, benzene and naphthalene under anaerobic conditions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aromatic hydrocarbons are widespread in nature, due to increasing industrial activity, and often contribute to polluted soils, sediments, and groundwater. Most of these compounds are toxic at relatively high concentrations, but some are already carcinogenic at very low concentrations, e.g. benzene. A growing awareness of the health risks associated with contamination has directed research to the removal or degradation of such compounds. The use of microorganisms to degrade toxic compounds (bi...

1997-01-01

31

Kinetics of the reactions of hydroxyl radical with benzene and toluene  

International Nuclear Information System (INIS)

Absolute rate constants for the reactions of the hydroxyl radical with benzene and toluene were measured within the temperature and pressure ranges 213 less than or equal to T less than or equal to 1150 K and 20 less than or equal to P less than or equal to 200 torr by using He, Ar, and SF_6 as diluent gases. To help elucidate the variations in reaction mechanism with temperature, we also studied OH reactions with deuterated benzene (C_6D_6) and with selectively deuterated toluenes (C_6H_5CD_3, C_6D_5CD_3, and C_6D_5CH_3). Three major reaction channels were characterized kinetically. At T less than or equal to 298 K, electrophilic addition of the OH radical to the aromatic ring is the dominant reactive pathway in all systems studied. At temperatures above 500 K, rapid decomposition of the thermalized adduct back to reactants diminishes the importance of the addition channel and leads to bimolecular reaction rate-constant values significantly lower than those measured near room temperature. At elevated temperatures, the ring hydrogen abstraction (for benzene) and side-chain hydrogen abstraction (for toluene) pathways are shown to be predominant. The measured bimolecular rate constants increase monotonically with increases in temperature above 500 K, and kinetic separation of the two hydrogen abstraction modes for toluene is achieved

1981-07-23

32

Penetration of benzene, toluene and xylenes contained in gasolines through human abdominal skin in vitro.  

Science.gov (United States)

Few studies are available in literature on the risk for humans from skin exposure to gasolines. This work is focused on the in vitro skin penetration of benzene (carcinogenic substance), toluene and xylenes. We examined three commercial gasolines using the Franz diffusion cells and human abdominal full thickness skin. Gasoline composition was determined using a multi-dimensional gas chromatographic (MDGC) technique. Aromatic compounds into the receptor fluid, consisting of saline solution were quantitated by a gas chromatography technique equipped with a flame ionization detector (GC-FID) and coupled with a headspace-solid phase micro extraction system (HS-SPME). Among the three substances, benzene showed the highest average apparent permeability coefficient (K(p)=43.8x10(-5)cmh(-1)) compared to toluene (K(p)=6.48x10(-5)cmh(-1)) and xylenes (K(p)=0.84x10(-5)cmh(-1)). This value could be explained by the lower boiling point and higher water solubility of benzene. Lag times were about 1h for benzene and 2h for toluene and xylenes. Averaged total recoveries in the receptor fluid were 0.43% of dose for benzene, 0.06% for toluene and 0.008% for xylenes. A statistical significative difference (Student's t-test, P<0.05) between the fluxes calculated for the three gasolines are noted only for xylene and for toluene between gasolines #1 (richer in aromatic compounds) and #3. The obtained apparent permeability coefficient are useful for determining the permeability of these aromatics components from gasolines of a different composition. Hands exposure risk, calculated using RfD and RfC as defined by US EPA, is critical for benzene. The risk of skin permeation of gasoline, and, in particular, of benzene, should be better evaluated for those workers who have a large potential for exposure. Adequate personal protective equipment should be used in the high exposure jobs, mainly for hands and forearms. PMID:16829017

Adami, G; Larese, F; Venier, M; Barbieri, P; Lo Coco, F; Reisenhofer, E

2006-12-01

33

Nucleotide sequence analysis of genes encoding a toluene/benzene-2-monooxygenase from Pseudomonas sp. strain JS150.  

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It was previously shown by others that Pseudomonas sp. strain JS150 metabolizes benzene and alkyl- and chloro-substituted benzenes by using dioxygenase-initiated pathways coupled with multiple downstream metabolic pathways to accommodate catechol metabolism. By cloning genes encoding benzene-degradative enzymes, we found that strain JS150 also carries genes for a toluene/benzene-2-monooxygenase. The gene cluster encoding a 2-monooxygenase and its cognate regulator was cloned from a plasmid ca...

Johnson, G. R.; Olsen, R. H.

1995-01-01

34

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

35

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

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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 reac...

2013-01-01

36

Simultaneous Determination of Benzene and Toluene in Pesticide Emulsifiable Concentrate by Headspace GC-MS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The toxic inert ingredients in pesticide formulations are strictly regulated in many countries. In this paper, a simple and efficient headspace-gas chromatography-mass spectrometry (HSGC-MS) method using fluorobenzene as an internal standard (IS) for rapid simultaneous determination of benzene and toluene in pesticide emulsifiable concentrate (EC) was established. The headspace and GC-MS conditions were investigated and developed. A nonpolar fused silica Rtx-5 capillary column (30?m × 0.20...

Cao, Lidong; Jiang, Hua; Yang, Jing; Fan, Li; Li, Fengmin; Huang, Qiliang

2013-01-01

37

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

Science.gov (United States)

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

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

1995-01-01

38

Secondary organic aerosol formation from m-xylene, toluene, and benzene  

Directory of Open Access Journals (Sweden)

Full Text Available Secondary organic aerosol (SOA formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2 react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene, the SOA yields (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted under low-NOx conditions substantially exceed those under high-NOx conditions, suggesting the importance of peroxy radical chemistry in SOA formation. Under low-NOx conditions, the SOA yields for m-xylene, toluene, and benzene are constant (36%, 30%, and 37%, respectively, indicating that the SOA formed is essentially nonvolatile. Under high-NOx conditions, aerosol growth occurs essentially immediately, even when NO concentration is high. The SOA yield curves exhibit behavior similar to that observed by Odum et al. (1996, 1997a, b, although the values are somewhat higher than in the earlier study. The yields measured under high-NOx conditions are higher than previous measurements, suggesting a "rate effect" in SOA formation, in which SOA yields are higher when the oxidation rate is faster. Experiments carried out in the presence of acidic seed aerosol reveal no change of SOA yields from the aromatics as compared with those using neutral seed aerosol.

J. H. Seinfeld

2007-03-01

39

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 (C_6H_6, C_6D_6) and toluene (C_6H_5-CH_3, C_6D_5-CD_3) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10"-"4 cm"2/s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

1981-01-01

40

Ambient air levels and occupational exposure to benzene, toluene, and xylenes in northwestern Italy.  

Science.gov (United States)

The purpose of this study was to determine benzene, toluene, and xylenes air pollution in two cities in Italy (Biella and Torino) having different traffic intesities and to investigate whether new environmental conditions occurred consequent to the changes of gasoline composition in Europe during the last 20 yr. Furthermore, three types of urban occupational exposure (petrol pump attendants, traffic policemen, and municipal employees) to the same hydrocarbons were compared to verify three different expected levels of exposure. Results in Biella demonstrate a direct relationship between traffic density and level of human exposure to these pollutants. Air concentrations for benzene were 2.3 micrograms/m3 in a suburban area having low traffic and 10.3 micrograms/m3 in the central area having high traffic. The comparison to trend analysis recently carried out in Torino indicates it is possible to improve the situation in the central area of Biella by adopting the same traffic limitations imposed in Torino. Personal sampling devices demonstrated that only the petrol pump attendants show, by means of a multivariate analysis, statistically significant higher levels of benzene compared to the other two professional categories, in both winter and summer. Values found in the present study for petrol pump attendants were around 1 mg/m3. Environmental and occupational exposure to benzene, toluene, and xylenes could be largely lowered by adopting preventive measures including traffic restrictions, the reduction of aromatic chemical content in gasoline, and the recovery of gasoline vapors at petrol pump stations. PMID:12712594

Bono, Roberto; Scursatone, Enzo; Schilirò, Tiziana; Gilli, Giorgio

2003-03-28

 
 
 
 
41

Coordination chemistry of metal surfaces. 3. Benzene and toluene interactions with nickel surfaces  

International Nuclear Information System (INIS)

Ni surfaces were the low Miller index planes (111), (110), and (100) and the stepped and stepped-kinked surfaces 9(111) x (111) and 7(111) x (310). Effects of surface C and O were established for low surface coverages. Benzene chemisorption was fully associative (molecular) on Ni(111) up to 100"0C; no H-D exchange occurred between C_6H_6 and C_6D_6 up to 100"0C. Up to 100"0C, benzene was displaced as C_6H_6(g) by P(CH_3)_3. Benzene reversible thermal desorption occurred at 115 to 125"0C, accompanied by extensive irreversible decomposition to H_2(g) + Ni(111)-C. Analogous behavior was observed for benzene chemisorbed on the stepped and stepped-kinked surface. On the (110) surface, the benzene thermal desorption and benzene chemical displacement by P(CH_3)_3 was comparable to the stepped-kinked surface. Chemisorption of benzene on Ni(100) was differentiated from the other surfaces: the degree of thermal reversibility was higher than and the temperature for the thermal desorption maximum was 100"0C higher than that for Ni(111). H-D exchange did not occur with D_2 + C_6H_6 and with C_6H_6 + C_6D_6 on Ni(100). Toluene chemisorption on all the nickel surfaces was thermally irreversible and toluene was not displaced from these surfaces by strong field ligands like P(CH_3)_3 and CH_3NC. Heating the Ni-toluene surfaces led to hydrogen evolution. For the decomposition of C_6D_5CD_3 on Ni(111) there were two D_2 thermal desorption maxima, 130 and 190"0C. For the analogous decomposition of C_6H_5CD_3 and C_6D_5CH_3 respectively, there were single D_2 desorption curves with maxima at 130 and 185"0C, respectively. Thus, aliphatic C-H bonds are broken first and no aromatic C-H bond is broken until near 160"0C. Identical behavior was observed for the stepped and stepped-kinked surfaces, and an analogous behavior was observed for the (100) surface

1981-02-25

42

Separation of aromatic hydrocarbons (toluene or benzene) from aliphatic hydrocarbon (n-heptane) by extraction with ethylene carbonate  

Energy Technology Data Exchange (ETDEWEB)

Selectivity factors and partition coefficients of ethylene carbonate and the (ethylene carbonate + sulfolane) solvent mixture for the separation of benzene or toluene from (benzene or toluene + n-heptane) are obtained from the experimental (liquid + liquid) equilibrium data for ternary mixtures of (ethylene carbonate + benzene or toluene + n-heptane) at temperatures of (303.15 and 313.15) K and quaternary mixture of (ethylene carbonate + sulfolane + benzene + n-heptane) at 303.15 K. The composition of liquid phases at equilibrium was determined by gas-liquid chromatography and the results were correlated with the UNIQUAC and NRTL activity coefficient models. The parameters of the models were evaluated and reported. The phase diagrams for the mixtures studied are presented and the correlated tie line results have been compared with the experimental results. The comparisons indicate the applicability of the UNIQUAC and NRTL activity coefficients model for (liquid + liquid) equilibrium calculations of the mixtures studied.

Mohsen-Nia, M., E-mail: m.mohsennia@kashanu.ac.i [Thermodynamic Research Laboratory, University of Kashan, Kashan (Iran, Islamic Republic of); Department of Chemical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Mohammad Doulabi, F.S. [Thermodynamic Research Laboratory, University of Kashan, Kashan (Iran, Islamic Republic of)

2010-10-15

43

Separation of aromatic hydrocarbons (toluene or benzene) from aliphatic hydrocarbon (n-heptane) by extraction with ethylene carbonate  

International Nuclear Information System (INIS)

Selectivity factors and partition coefficients of ethylene carbonate and the (ethylene carbonate + sulfolane) solvent mixture for the separation of benzene or toluene from (benzene or toluene + n-heptane) are obtained from the experimental (liquid + liquid) equilibrium data for ternary mixtures of (ethylene carbonate + benzene or toluene + n-heptane) at temperatures of (303.15 and 313.15) K and quaternary mixture of (ethylene carbonate + sulfolane + benzene + n-heptane) at 303.15 K. The composition of liquid phases at equilibrium was determined by gas-liquid chromatography and the results were correlated with the UNIQUAC and NRTL activity coefficient models. The parameters of the models were evaluated and reported. The phase diagrams for the mixtures studied are presented and the correlated tie line results have been compared with the experimental results. The comparisons indicate the applicability of the UNIQUAC and NRTL activity coefficients model for (liquid + liquid) equilibrium calculations of the mixtures studied.

2010-10-01

44

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

45

Carbon and hydrogen isotope fractionation of benzene and toluene during hydrophobic sorption in multistep batch experiments.  

Science.gov (United States)

The application of compound-specific stable isotope analysis (CSIA) for evaluating degradation of organic pollutants in the field implies that other processes affecting pollutant concentration are minor with respect to isotope fractionation. Sorption is associated with minor isotope fractionation and pollutants may undergo successive sorption-desorption steps during their migration in aquifers. However, little is known about isotope fractionation of BTEX compounds after consecutive sorption steps. Here, we show that partitioning of benzene and toluene between water and organic sorbents (i.e. 1-octanol, dichloromethane, cyclohexane, hexanoic acid and Amberlite XAD-2) generally exhibits very small carbon and hydrogen isotope effects in multistep batch experiments. However, carbon and hydrogen isotope fractionation was observed for the benzene-octanol pair after several sorption steps (??(13)C=1.6±0.3‰ and ??(2)H=88±3‰), yielding isotope fractionation factors of ?C=1.0030±0.0005 and ?H=1.195±0.026. Our results indicate that the cumulative effect of successive hydrophobic partitioning steps in an aquifer generally results in insignificant isotope fractionation for benzene and toluene. However, significant carbon and hydrogen isotope fractionation cannot be excluded for specific sorbate-sorbent pairs, such as sorbates with ?-electrons and sorbents with OH-groups. Consequently, functional groups of sedimentary organic matter (SOM) may specifically interact with BTEX compounds migrating in an aquifer, thereby resulting in potentially relevant isotope fractionation. PMID:24726480

Imfeld, G; Kopinke, F-D; Fischer, A; Richnow, H-H

2014-07-01

46

Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenze, and Xylene (BTEX) Hydrocarbons by the Fungus Cladophialophora sp. Strain T1  

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The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene, ethylbenzene, and xylenes) were degraded by a combination of assimilation and cometabolism. Toluene and ethylbenzene were used as sources of carbon and energy, whereas the xylenes were cometabolized to...

Prenafeta-boldu?, F. X.; Vervoort, J.; Grotenhuis, J. T. C.; Groenestijn, J. W.

2002-01-01

47

Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Hydrocarbons by the Fungus Cladophialophora sp. Strain T1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene, ethylbenzene, and xylenes) were degraded by a combination of assimilation and cometabolism. Toluene and ethylbenzene were used as sources of carbon and energy, whereas the xylenes were cometabolized to...

Prenafeta-boldu?, F. X.; Vervoort, J.; Grotenhuis, J. T. C.; Groenestijn, J. W.

2002-01-01

48

Simultaneous determination of methyl tert.-butyl ether and its degradation products, other gasoline oxygenates and benzene, toluene, ethylbenzene and xylenes in Catalonian groundwater by purge-and-trap-gas chromatography-mass spectrometry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In Catalonia (northeast Spain), a monitoring program was carried out to determine methyl tert.-butyl ether (MTBE), its main degradation products, tert.-butyl alcohol (TBA), tert.-butyl formate (TBF), and other gasoline additives, the oxygenate dialkyl ethers ethyl tert.-butyl ether, tert.-amyl methyl ether and diisopropyl ether and the aromatic compounds benzene, toluene, ethylbenzene and xylene (BTEX) in 21 groundwater wells that were located near different gasoline point sources (a gasoline...

Rosell Linares, Mo?nica; Lacorte Bruguera, Silvia; Ginebreda Marti?, Antoni; Barcelo?, Damia?

2003-01-01

49

Reactions of the CN radical with benzene and toluene: product detection and low-temperature kinetics.  

Science.gov (United States)

Low-temperature rate coefficients are measured for the CN + benzene and CN + toluene reactions using the pulsed Laval nozzle expansion technique coupled with laser-induced fluorescence detection. The CN + benzene reaction rate coefficient at 105, 165, and 295 K is found to be relatively constant over this temperature range, (3.9-4.9) x 10(-10) cm(3) molecule(-1) s(-1). These rapid kinetics, along with the observed negligible temperature dependence, are consistent with a barrierless reaction entrance channel and reaction efficiencies approaching unity. The CN + toluene reaction is measured to have a rate coefficient of 1.3 x 10(-10) cm(3) molecule(-1) s(-1) at 105 K. At room temperature, nonexponential decay profiles are observed for this reaction that may suggest significant back-dissociation of intermediate complexes. In separate experiments, the products of these reactions are probed at room temperature using synchrotron VUV photoionization mass spectrometry. For CN + benzene, cyanobenzene (C(6)H(5)CN) is the only product recorded with no detectable evidence for a C(6)H(5) + HCN product channel. In the case of CN + toluene, cyanotoluene (NCC(6)H(4)CH(3)) constitutes the only detected product. It is not possible to differentiate among the ortho, meta, and para isomers of cyanotoluene because of their similar ionization energies and the approximately 40 meV photon energy resolution of the experiment. There is no significant detection of benzyl radicals (C(6)H(5)CH(2)) that would suggest a H-abstraction or a HCN elimination channel is prominent at these conditions. As both reactions are measured to be rapid at 105 K, appearing to have barrierless entrance channels, it follows that they will proceed efficiently at the temperatures of Saturn's moon Titan ( approximately 100 K) and are also likely to proceed at the temperature of interstellar clouds (10-20 K). PMID:20043665

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

2010-02-01

50

Secondary organic aerosol formation from m-xylene, toluene, and benzene  

Directory of Open Access Journals (Sweden)

Full Text Available Secondary organic aerosol (SOA formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2 react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene, the SOA yields (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted under low-NOx conditions substantially exceed those under high-NOx conditions, suggesting the importance of peroxy radical chemistry in SOA formation. Under low-NOx conditions, the SOA yields for m-xylene, toluene, and benzene are constant (36%, 30%, and 37%, respectively, indicating that the SOA formed is effectively nonvolatile under the range of Mo(>10 ?g m?3 studied. Under high-NOx conditions, aerosol growth occurs essentially immediately, even when NO concentration is high. The SOA yield curves exhibit behavior similar to that observed by Odum et al. (1996, 1997a, b, although the values are somewhat higher than in the earlier study. The yields measured under high-NOx conditions are higher than previous measurements, suggesting a "rate effect" in SOA formation, in which SOA yields are higher when the oxidation rate is faster. Experiments carried out in the presence of acidic seed aerosol reveal no change of SOA yields from the aromatics as compared with those using neutral seed aerosol.

J. H. Seinfeld

2007-07-01

51

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

Science.gov (United States)

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

2014-01-01

52

Degradation of a benzene-toluene mixture by hydrocarbon-adapted bacterial communities.  

Science.gov (United States)

We examined the rate of degradation of a benzene-toluene mixture in aerobic microcosms prepared with samples of an aquifer that lies below a petrochemical plant (SIReN, UK). Five samples exposed to different concentrations of benzene (from 0.6 to 317 mg l(-1)) were used. Fast degradation (approx. 1-6 mg l(-1) day(-1)) of both contaminants was observed in all groundwater samples and complete degradation was recorded by the seventh day except for one sample. We also identified the microbial community in each of the samples by culture-independent techniques. Two of the less impacted samples harbour the aerobic benzene degrader Pseudomonas fluorescens, while Acidovorax and Arthrobacter spp. were found in the most polluted sample and are consistent with the population observed in situ. Hydrogenophaga was found in the deepest sample while Rhodoferax spp. were recovered in an alkaline sample (pH 8.4) and may also be implicated in benzene degradation. Time series analysis shows that each of the samples has a different community but they remain stable over the degradation period. This study provides new information on a well not previously studied (no. 309s) and confirms that adapted communities have the ability to degrade hydrocarbon mixtures and could be used in further bioaugmentation approaches in contaminated sites. PMID:21949494

Aburto, Arturo; Peimbert, Mariana

2011-09-01

53

Study of adsorption structure of benzene and toluene on Si(1 1 1)7 × 7 surfaces  

Science.gov (United States)

The adsorption of benzene and toluene on Si(1 1 1)7 × 7 was investigated using scanning tunneling microscopy (STM) and theoretical calculations. For both aromatic molecules, bright spots in the STM images and populations of the subunits, each consisting of three reacted adatoms, indicated that an adsorbed molecule is involved in a configuration with an adatom and its adjacent rest atom. The structures of adsorbed benzene and toluene were also examined using theoretical calculations involving the cluster model of Si 30H 28. Several structures were obtained as energetically favorable structures using geometrical optimization calculations. By comparing the binding energies of each structure, the 1,4-cyclohexadiene-like adsorption structure was found to be most energetically favorable for benzene and toluene adsorption. These calculated adsorption structures are in good agreement with the experimental results.

Tomimoto, Hiroyuki; Sekitani, Tetsuji; Sumii, Ryohei; Oda Sako, Erika; Wada, Shin-ichi; Tanaka, Kenichiro

2004-09-01

54

Benzene, toluene and xylenes levels in new and used vehicles of the same model.  

Science.gov (United States)

The aim of this work was to determine the level of benzene, toluene, o-xylene and m, p-xylene (BTX) in air samples collected from the cabins of new and used vehicles of the same model. Ten new vehicles were examined in order to check interior emission from materials used to equip the passenger compartment. In order to compare and define the impact of exhaust gases, air samples were also collected from two used cars, at different mileages (up to 20,000 km). All vehicles tested were of the same type. Samples were collected onto Carbograph 1TD sorbent, thermally desorbed and examined with the use of gas chromatography with flame ionisation and mass spectrometry detectors. All results obtained were referred to Polish and German requirements for indoor air quality (both in public buildings and in workspace environments). Average benzene, toluene, o-xylene and m, p-xylene concentrations in new cars were determined at the level of 11.8 microg/m3, 82.7 micro/m3, 21.2 microg/m3 and 89.5 micro/m3, respectively. In the used cars, BTX concentration increased with increasing vehicle mileage. The most significant increase of BTX concentration was observed above 11,000 km mileage. PMID:24552062

Faber, Joanna; Brodzik, Krzysztof; Golda-Kopek, Anna; Lomankiewicz, Damian

2013-11-01

55

Energy resolution measurements of benzene, toluene and cyclohexane scintillators for monoenergetic ?-rays  

International Nuclear Information System (INIS)

Energy resolution and difference of the maximum energy of Compton electrons from the half-height of the Compton edge was measured experimentally for benzene (C6H6), cyclohexane (C6H12) and toluene scintillators for monoenergetic ?-rays using a ?-? coincidence technique. For 0.5-1.2 MeV ?-rays, the energy resolution for C6H6, C6H12 and toluene scintillators varies from 23.8-12.6%, 28.6-2.5% and 23.5-4.6%, respectively. The corresponding energy difference between the maximum Compton electron energy and the half height of the Compton edge for C6H6, C6H12 and toluene scintillators varies from 13.2-7.6%, 17.7-10.2% and 10.2-6.8%, respectively. The energy resolution of the C6H6 detector agrees within 5-10% of that obtained with an identical C6D6 scintillator. (author)

1996-02-01

56

High energy electron beam generation of oxidants for the treatment of benzene and toluene in the presence of radical scavengers  

International Nuclear Information System (INIS)

High energy electron beam irradiation of benzene and toluene in aqueous solution results in their destruction and the formation of highly oxidized reaction byproducts. The product distribution depends upon absorbed dose and pH and results from the reaction of benzene and toluene with the hydroxyl radical (OH·), followed by continued oxidation of intermediate by-products. The dose required to remove 99% (D0.99) of the benzene from solution, at an initial solute concentration of 17.0 ? M (1.3 mg l-1), was 95 krad. In presence of a known radical scavenger, i.e. 3.3 mM methanol, a dose of 1510 krad was required to achieve the same removal. Toluene showed greater removal, in the absence of methanol, than benzene under similar experimental condition. The D0.99 required to destroy an initial toluene concentration of 47.7 ?M (4.4 mg l-1) was 165 krad, whereas the D0.99 for an initial toluene concentration of 16.4 ? M, in the presence of 3.3 mM methanol, was 2074 krad. (Author)

1994-05-01

57

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

58

Combination of the tod and the tol pathways in redesigning a metabolic route of Pseudomonas putida for the mineralization of a benzene, toluene, and p-xylene mixture.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Construction of a hybrid strain which is capable of mineralizing components of a benzene, toluene, and p-xylene mixture simultaneously was attempted by redesigning the metabolic pathway of Pseudomonas putida. Genetic and biochemical analyses of the tod and the tol pathways revealed that dihydrodiols formed from benzene, toluene, and p-xylene by toluene dioxygenase in the tod pathway could be channeled into the tol pathway by the action of cis-p-toluate-dihydrodiol dehydrogenase, leading to co...

Lee, J. Y.; Jung, K. H.; Choi, S. H.; Kim, H. S.

1995-01-01

59

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

60

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

International Nuclear Information System (INIS)

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

1991-01-01

 
 
 
 
61

UV Fourier transform absorption cross sections of benzene, toluene, meta-, ortho-, and para-xylene  

International Nuclear Information System (INIS)

New measurements of the absorption cross sections of gaseous benzene, toluene, meta-, ortho-, and para-xylene have been performed with a Fourier transform spectrometer Bruker IFS120 M at the resolution of 1 cm-1 over the 30 000-42 000 cm-1 spectral range. The recordings were carried out under different pressure and temperature conditions with pure samples. The effect of the temperature on the absorption cross sections is investigated. Comparison with the literature shows large differences, largely attributed to the experimental difficulties encountered during these previous measurements and to a resolution effect. To our knowledge, it is the first time that such a dataset of UV absorption cross sections with temperature dependence is reported in the literature. Such data should be useful for upcoming remote sensing applications, such as atmospheric studies both on Earth and on other planets.

2009-01-01

62

Effects of acute exposure of toluene and methyl ethyl ketone on psychomotor performance  

Energy Technology Data Exchange (ETDEWEB)

Organic solvents are used frequently in industry and workers are often exposed to various combinations of these chemicals. Several are CNS depressants, and the purpose of this experiment was to assess the behavioral effects of 4-hour inhalation exposures to two solvents, toluene and methyl ethyl ketone (MEK) alone and combined. Ethanol at 0.08% blood levels was used as a positive control. A total of 144 paid volunteers were randomly assigned to one of eight treatment combinations in a series of four two-group between subjects studies. Results indicated that toluene at 100 ppm produced a small but significant impairment on one measure of a visual-vigilance task by lowering the percentage of correct hits. MEK at 200 ppm produced no interpretable significant effects on any of these measures. Additivity was not evident when individuals were exposed to MEK (100 ppm) and toluene (50 ppm) in combination, as no significant performance differences were noted. Ethanol, at 0.08%, affected both the visual-vigilance and a choice-reaction time task at statistically significant levels on two measures, confirming the sensitivity of these two tasks to CNS depressants.

Dick, R.B.; Setzer, J.V.; Wait, R.; Hayden, M.B.; Taylor, B.J.; Tolos, B.; Putz-Anderson, V.

1984-01-01

63

Mobility of Supercooled liquid Toluene, Ethylbenzene, and Benzene near their Glass Transition Temperatures Investigated using Inert Gas Permeation  

Energy Technology Data Exchange (ETDEWEB)

We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg and as a result the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 K to 135 K. In this temperature range, diffusivities are found to vary across five orders of magnitude (~10-14 to 10-9 cm2/s). These data are compared to viscosity measurements and used to determine the low temperature fractional Stokes-Einstein exponent. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

May, Robert A.; Smith, R. Scott; Kay, Bruce D.

2013-11-21

64

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

International Nuclear Information System (INIS)

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

1993-01-01

65

Thermodynamics of mixtures containing oxaalkanes. 6. Random mixing in ether + benzene, or + toluene systems  

International Nuclear Information System (INIS)

The Flory model has been applied to linear or cyclic ether + benzene, or +toluene mixtures. In addition, the relative variation of the molar excess enthalpy, HmE, along homologous series of the considered systems, has been discussed taking into account the contributions to HmE from the ether-ether, aromatic-aromatic and ether-aromatic interactions. It has been shown that in CH3(CH2)u-1O(CH2CH2O)v(CH2)u-1CH3 + benzene mixtures, the u increase (v fixed) leads to a weakening of interactions between unlike molecules, and that proximity effects also weaken this type of interactions. In contrast, the v increase (u fixed) or cyclization lead to stronger interactions between unlike molecules. From the application of the model, it is concluded that the random mixing hypothesis may be considered to be valid to a large extent for many of the investigated solutions. Erroneously, strong orientational effects are predicted for 1,3-dioxolane, or 1,4-dioxane + benzene systems, but this has been attributed to the model can not describe asymmetric HmE curves when the mixture compounds show close values for Vi (molar volume) and for Vi* (reduction parameter for volume). Previous calculations on the basis of the Kirkwood-Buff integrals formalism confirm that the mixture structure is close to random mixing. Flory results on the excess molar volumes have been discussed taking into account the so-called curvature and P* contributions to this excess function.

2011-02-20

66

Analysis of benzene, toluene, ethylbenzene and xylenes in soils by headspace and gas chromatography/flame ionization detector  

Directory of Open Access Journals (Sweden)

Full Text Available The constituents of gasoline: benzene, toluene, ethylbenzene and xylenes (BTEX are frequently found in soils due to leaks in fuel storage tanks and they present chronic toxicity. In this work it was developed and validated a methodology of BTEX analysis in soil by gas chromatography/ flame ionization detector and static headspace. The recovery of BTEX in soil samples was evaluated using soils with different textures (sandy and loamy. The analysis method showed good resolution, in a low time of analysis (less than 30 minutes. Limits of quantification of 0.05 mg Kg¯¹ soil for benzene, toluene, ethylbenzene and xylenes are below the guiding values that range from 0.15 to 95 mg Kg¯¹ soil, established to determine soil quality. It was verified that the methodology enables the use of this method for BTEX analysis of soil samples for passive environmental identification of gas stations.

Jurandir Pereira Pinto

2006-02-01

67

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Benzene, toluene, and p-xylene (BTX) were degraded by indigenous mixed cultures in sandy aquifer material and by two pure cultures isolated from the same site. Although BTX compounds have a similar chemical structure, the fate of individual BTX compounds differed when the compounds were fed to each pure culture and mixed culture aquifer slurries. The identification of substrate interactions aided the understanding of this behavior. Beneficial substrate interactions included enhanced degradati...

1991-01-01

68

The rate constants for reaction of {sup {center_dot}}OH radicals with benzene and toluene  

Energy Technology Data Exchange (ETDEWEB)

The rate constant for reaction of {sup {center_dot}}OH radical with toluene in aqueous solutions saturated with N{sub 2}O or containing 0.1 M H{sub 2}O{sub 2} has been determined by pulse radiolysis to be 8.1x10{sup 9} l mol{sup -1} s{sup -1}. This rate constant is comparable to the value of 7.8x10{sup 9} l mol{sup -1} s{sup -1} for reaction with benzene determined under similar conditions. This latter rate constant provides a reference value of 1.3x10{sup 9} l mol{sup -1} s{sup -1} with which to compare the partial rate constants for reaction of {sup {center_dot}}OH at the various positions of substituted aromatics. Comparison of the kinetic responses in the N{sub 2}O and H{sub 2}O{sub 2} systems provides a direct measure of the pseudo-first-order rate constant for reaction of {sup {center_dot}}O{sup -} with water as 7.9x10{sup 7} s{sup -1}.

Schuler, Robert H. E-mail: schuler.1@nd.edu; Albarran, Guadalupe

2002-06-01

69

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, ?-Al2O3/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. PMID:23681937

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

2014-03-01

70

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

International Nuclear Information System (INIS)

It was determined Benzene, Toluene and Xylene (BTX) levels in air from paint manufacture assigned to Instituto Colombiano de Seguro Social with the purpose to evaluate the occupational hazard caused by the use of these solvents. These results were compared with the threshold limit value (TLV). It was selected as sampling strategy, the methodology of partial period with consecutive samples and charcoal tubes as adsorbent of solvents. The extraction was realized with carbon disulfide and it was used gas chromatography with FID as analysis method. It was found that the method is highly selective because in presence of the others ten solvents, utilized in paint manufacture, were obtained a good separation for BTX. The precision, expressed a variance coefficient, was lower than 10%, the accuracy varied between 85 and 99 % for the three solvents. The airborne concentration found was between no detectable and 55,1 mg/m3 for benzene, 18,3 and 253 mg/m3 for toluene and 11,8 and 122,2 mg/m3 for xylene. The corrected TLV values for benzene, toluene and xylenes according to the brief and scale model for the ten hours shift were 1,1, 132 and 304 mg/m3 respectively. It was found occupational risk for benzene in some workplaces; this one is worried because benzene is not used as raw material for the paint manufacture. It was determinate that exist occupational risk in almost every workplace of the industry when it is considered the mixture of the three solvents

2002-01-01

71

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

72

The Role of Acid Strength of Modified NaX Zeoliteson Gas Phase Ethylation of Benzene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The role of acid strength of modified NaX zeolites in gas phase ethylation of benzene were studied over Ce exchanged NaX zeolite of different types. Acidity of the modified zeolite was investigated by means of adsorbing ammonia at different temperature. The conversion of reactantsvaries with the acid strength as well as the different types of the zeolites. The strong acid sites are active centers while the weak acid sites are inactive. The influences of various process parameters such as temp...

Sanghamitra Barman

2010-01-01

73

Redetermination of ethyl­ene­diammonium bis­(p-methyl­benzene­sulfonate) monohydrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the asymmetric unit of the title compound, C2H10N2 2+·2C7H7O3S?·H2O, there are two independent 4-methyl­benzene­sulfonate anions, one ethyl­enediammonium cation and a water mol­ecule. The present redetermination was carried out to improve the treatment of disorder, which was not refined in the previous study [Ahn & Kim (1985 ?). J. Korean Chem. Soc. 29, 335–340]. One of the sulfonate groups is disordered over two positions, with site-occupan...

Shen-tu, Chao; Ma, Lin-lin; Xu, Wei; Chen, Ying; Jin, Zhi-min

2007-01-01

74

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

2001-10-01

75

Removal of benzene and methyl ethyl ketone vapor: comparison of hypercrosslinked polymeric adsorbent with activated carbon.  

Science.gov (United States)

A novel hypercrosslinked polymeric adsorbent (HY-1) with high surface area and specific bimodal pore size distribution in the regions of micropore (0.5-2.0 nm) and meso-macropore (30-70 nm) was prepared. Adsorption properties of benzene and methyl ethyl ketone (MEK) vapors onto HY-1 were investigated and compared with a commercial microporous activated carbon (m-GAC). The equilibrium adsorption data showed that the adsorption capacities of benzene and MEK on HY-1 were larger than those of m-GAC at the higher relative pressure. The Dubinin-Radushkevich (D-R) equation was found to fit the experimental data well. The isosteric enthalpy of adsorption for benzene and MEK were calculated. The m-GAC exhibited much higher values of ?H(st) for the VOCs than HY-1 at the whole loading studied, which can lead to significant temperature rises during the adsorption step. The results of dynamic experiments revealed that HY-1 had a good dynamic adsorption capacity with a longer breakthrough time and shorter length of mass transfer zone due to its specific bimodal property. Therefore, HY-1 will be a particularly efficient and competitive adsorbent for VOCs recovery, especially at medium-high concentrations. PMID:22204838

Long, Chao; Li, Ying; Yu, Weihua; Li, Aimin

2012-02-15

76

A Chromosomally Based tod-luxCDABE Whole-Cell Reporter for Benzene, Toluene, Ethybenzene, and Xylene (BTEX) Sensing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 who...

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

1998-01-01

77

Health Risk Assessment of Ambient Air Concentrations of Benzene, Toluene and Xylene (BTX in Service Station Environments  

Directory of Open Access Journals (Sweden)

Full Text Available A comprehensive evaluation of the adverse health effects of human exposures to BTX from service station emissions was carried out using BTX exposure data from the scientific literature. The data was grouped into different scenarios based on activity, location and occupation and plotted as Cumulative Probability Distributions (CPD plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ at 50% (CEXP50 and 95% (CEXP95 exposure levels. HQ50 and HQ95 > 1 were obtained with benzene in the scenario for service station attendants and mechanics repairing petrol dispensing pumps indicating a possible health risk. The risk was minimized for service stations using vapour recovery systems which greatly reduced the benzene exposure levels. HQ50 and HQ95 < 1 were obtained for all other scenarios with benzene suggesting minimal risk for most of the exposed population. However, HQ50 and HQ95 < 1 was also found with toluene and xylene for all scenarios, suggesting minimal health risk. The lifetime excess Cancer Risk (CR and Overall Risk Probability for cancer on exposure to benzene was calculated for all Scenarios and this was higher amongst service station attendants than any other scenario.

Benjamin Edokpolo

2014-06-01

78

Vapour generation-Fourier transform infrared spectrometric determination of benzene, toluene and methyl tert.-butyl ether in gasolines  

Energy Technology Data Exchange (ETDEWEB)

A simple and fast procedure has been developed for the direct and simultaneous determination by Fourier transform infrared (FTIR) spectrometry of benzene, toluene and methyl tert.-butyl ether (MTBE) in gasoline samples. The method is based on the injection of 1{mu}l of gasoline into an electrically heated Pyrex glass reactor in which the sample is volatilized at 90C. The vapour generated is transported by means of a nitrogen carrier flow of 400 ml min{sup -1} inside an IR multiple pass gas cell and the spectrum in the mid-IR region is registered between 1600 and 500 cm{sup -1} as a function of time. The flow injection recordings obtained for the IR bands between 671-675 cm{sup -1}, 727-731 cm{sup -1}, and 1210-1214 cm{sup -1} were employed for the determination of benzene, toluene and MTBE respectively, using different criteria for establishing the baseline correction. Results obtained in the analysis of commercial samples of gasoline agree with those found by gas chromatography and another FTIR reference procedure

Lopez-Anreus, Emilio; Garrigues, Salvador; Guardia, Miguel de la [Department of Analytical Chemistry, University of Valencia, Valencia (Spain)

1996-10-30

79

Electrodeposited ZnO/ Zn Photo catalysts for the Degradation of Benzene-Toluene-Xylene Mixture in Aqueous Phase  

International Nuclear Information System (INIS)

The recognition of the ability of volatile organic compounds, (VOCs) to pollute the ground water is now well documented. VOCs such as benzene, toluene and xylene from the petroleum industries processed water leaked through the underground old piping system into the soils and groundwater during its transportation to the wastewater plant. Photo catalysis have been used as a potential system in the degradation of VOCs in the wastewater. However, the powdered form photo catalysts that were used in various studies are difficult to be separated from the aqueous solution at the end of the treatment. Therefore, the main objective of this research is to prepare the electrodeposited photo catalysts for the degradation of aromatic hydrocarbon mixture, benzene-toluene-xylene (BTX) solution under UV light (354 nm). The concentrations of electrolyte and electrodeposition voltages used to prepare the photo catalysts were studied for their efficiency in the degradation. From the research, ZnO/ Zn prepared in 0.8 M NaOH and under 12 V possessed the best catalytic degradation performance by degrading 32.37 % of BTX in the solution. The ZnO/ Zn photo catalyst was characterized using X-ray Diffraction Techniques (XRD) which illustrated high crystallinity of Zn species and reasonably high amorphous phase of ZnO species. (author)

2012-12-01

80

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

 
 
 
 
81

Evaluation of seawater contamination with benzene, toluene and xylene in EHE Ubatuba Region and study of their degradation by ionizing radiation  

International Nuclear Information System (INIS)

A major concern with leaking petroleum is the environmental contamination by 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 xylenes, and their removal by exposure to 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 headspace concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 ?g/L for benzene, 0.70 /L for toluene, and 1.54 /L for xylenes, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MDL, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylenes, 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. The results showed 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. For toluene the removal were from 20% to 60% with 15 kGy and xylenes were removed from 20% to 80% with 15 kGy and similar concentrations. (author)

2007-10-05

82

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

83

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

Science.gov (United States)

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 microM. 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 microM. 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 microM. 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. PMID:17900805

Chen, Colin S; Hseu, You C; Liang, Shih H; Kuo, Jar-Yi; Chen, Ssu C

2008-05-01

84

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

International Nuclear Information System (INIS)

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

2009-03-01

85

Section i: Thermodynamic Properties of Hydrocarbon Radicals, Peroxy Hydrocarbon and Peroxy Chlorohydrocarbon Molecules and Radicals. Section II. Kinetics and Reaction Mechanisms For: (1) Chloroform Pyrolysis and Oxidation; (2) Benzene and Toluene Oxidation Under Atmospheric Conditions.  

Science.gov (United States)

Alkyl radicals are important active intermediates in gas phase photochemistry and combustion reaction systems. With the exception of a limited number of the most elementary radicals, accurate thermodynamic properties of alkyl radicals are either not available or only rough estimations exist. An H atom Bond Increment approach is developed and a data base is derived, for accurately estimating thermodynamic properties (Delta H_{f }^circ298, S ^circ298 and Cp(T)) for generic classes of hydrocarbon radical species. Reactions of alkyl radicals with molecular oxygen are one of the major reaction paths for these radicals in atmospheric photochemistry, oxidation of hydrocarbon liquids and combustion process. Alkyl hydroperoxides are subsequently formed through the alkyl peroxy radicals reactions with varied chemical species present in the reaction system. Thermodynamic properties of the alkyl hydroperoxides and related radicals are therefore frequently required in gas phase modeling and kinetic studies on these systems. The thermodynamic properties of alkyl hydroperoxides, alkyl peroxy radicals and hydroperoxyl-1-ethyl radicals including the species with fluorine and chlorine substituents on the alpha-carbon are evaluated using molecular orbital calculations. Chloroform is used as a model chlorocarbon system with high Cl/H ratio to investigate thermal decomposition processes of chlorocarbons in oxidative and pyrolytic reaction environments. A detailed reaction mechanism is developed to describe the important features of products and reagent loss and is shown to predict the experimental data well. Reaction pathways and rate constants are developed for CCl _3, CCl_2 and rm C_2Cl_3 radical addition to O_2 and combination with O, OH HO_2 and ClO. The reversible addition reaction of OH radical with benzene to form the hydroxyl-2,4-cyclohexadienyl (benzene -OH) adduct and the subsequent reactions of this benzene -OH adduct with O_2 are important initial steps for the photooxidation of benzene and other aromatic species in the atmosphere. OH addition to the benzene ring, the subsequent reaction of O_2 with the hydroxyl-2,4-cyclohexadienyl to form hydroxyl -2-peroxy-4-cyclohexenyl (benzene-OH-O_2 adduct), are chemical activation reactions and are a function of both pressure and temperature. The kinetics of these two reaction systems at various pressure & temperatures using a quantum version of Rice-Ramsperger-Kassel theory (QRRK) and a modified strong collision approach are analyzed and calculated. The analogue reaction system of toluene photooxidation is also analyzed. Reaction mechanisms are developed for initial steps of atmospheric oxidation of benzene and toluene, which include reverse reaction rates determined from thermodynamic parameters and microscopic reversibility. The model results show good agreement with the limited available experimental data.

Lay, Tsan-Horng

1995-01-01

86

Bubble point measurements of binary mixtures formed by ethyl benzene with selected compounds at 95.35 kPa  

International Nuclear Information System (INIS)

Bubble point temperatures (at 95.35 kPa) over the entire composition range were measured for the binary mixtures formed by ethyl benzene with: acetyl acetone, o-, and p-cresols, 1-hexanol, and tetraethoxysilane, employing a Swietoslawski type ebulliometer. Wilson equation was used to represent the measured liquid phase composition versus bubble point temperature data, and the computed values of the vapor phase mole fractions, activity coefficients, and excess Gibbs free energy were tabulated and briefly discussed

2008-09-01

87

Bubble point measurements of binary mixtures formed by ethyl benzene with selected compounds at 95.35 kPa  

Energy Technology Data Exchange (ETDEWEB)

Bubble point temperatures (at 95.35 kPa) over the entire composition range were measured for the binary mixtures formed by ethyl benzene with: acetyl acetone, o-, and p-cresols, 1-hexanol, and tetraethoxysilane, employing a Swietoslawski type ebulliometer. Wilson equation was used to represent the measured liquid phase composition versus bubble point temperature data, and the computed values of the vapor phase mole fractions, activity coefficients, and excess Gibbs free energy were tabulated and briefly discussed.

Vittal Prasad, T.E. [Properties Group, Chemical Engineering Laboratory, Indian Institute of Chemical Technology, Hyderabad 500 007 (India); Vasavi, M.; Jyotsna, M.; Jhansi, V.; Smitha, G. [Bhoj Reddy Engineering College for Women, Hyderabad 500 059 (India); Prasad, D.H.L. [Properties Group, Chemical Engineering Laboratory, Indian Institute of Chemical Technology, Hyderabad 500 007 (India)], E-mail: dasika@iict.res.in

2008-09-15

88

Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol).  

Science.gov (United States)

A reference material for the biological monitoring of occupational exposure to toluene, benzene and phenol was prepared. O-cresol and hippuric acid (metabolites of toluene) are used for the biological monitoring of occupational exposure to toluene. Phenol, a metabolite of benzene, is used for the biological monitoring of exposure to benzene, but phenol can of course also be used as an indicator of exposure to phenol as well. The reference material (RM) used for the determination of these metabolites was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to toluene and those taking part in an inhalation experiment. Tests for homogeneity and stability were performed by determining urine concentrations of o-cresol, hippuric acid, creatinine and phenol. To investigate the stability of the RM, the urinary concentrations of o-cresol and phenol were monitored for eighteen months using GC and HPLC, while those of hippuric acid and creatinine were followed for five and six years, respectively, using HPLC. Analysis of variance showed that the concentrations did not change. The certified concentration values (and their uncertainties) of the substances in this reference material (phenol concentration c=6.46+/-0.58 mg l(-1); o-cresol concentration c=1.17+/-0.15 mg l(-1); hippuric acid concentration c=1328+/-30 mg l(-1); creatinine concentration c=0.82+/-0.10 g l(-1)) were evaluated via the interactive statistical programme IPECA. PMID:16953321

Sperlingová, I; Dabrowská, L; Stránský, V; Kucera, J; Tichý, M

2007-04-01

89

Evaluation of seawater contamination with benzene, toluene and xylene in EHE Ubatuba Region and study of their degradation by ionizing radiation  

Energy Technology Data Exchange (ETDEWEB)

A major concern with leaking petroleum is the environmental contamination by 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 xylenes, and their removal by exposure to 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 headspace concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 {mu}g/L for benzene, 0.70 /L for toluene, and 1.54 /L for xylenes, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MDL, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylenes, 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 xylenes observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard were exposed to ionizing radiation using a source of {sup 60}Co. The results showed 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. For toluene the removal were from 20% to 60% with 15 kGy and xylenes were removed from 20% to 80% with 15 kGy and similar concentrations. (author)

Almeida, Kelly Cristina Santana de; Cardoso, Vanessa Miguel; Mori, Manoel Nunes; Duarte, Celina Lopes [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: kellycsalmeida@ig.com.br; vcardose@usp.br; mnmori@ipen.br; clduarte@ipen.br

2007-07-01

90

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

2004-10-01

91

Modeling annual benzene, toluene, NO2, and soot concentrations on the basis of road traffic characteristics  

International Nuclear Information System (INIS)

The investigation of potential adverse health effects of urban traffic-related air pollution is hampered by difficulties encountered with exposure assessment. Usually public measuring sites are few and thereby do not adequately describe spatial variation of pollutant levels over an urban area. In turn, individual monitoring of pollution exposure among study subjects is laborious and expensive. We therefore investigated whether traffic characteristics can be used to adequately predict benzene, NO2, and soot concentrations at individual addresses of study subjects in the city area of Munich, Germany. For all road segments with expected traffic volumes of at least 4000 vehicles a day (n=1840), all vehicles were counted manually or a single weekday in 1995. The proportion of vehicles in 'stop-go' mode, n estimate of traffic jam, was determined. Furthermore, annual concentrations of benzene, NO2, and soot from 18 high-concentration sites means: 8.7, 65.8, and 12.9 ?g/m3, respectively) and from 16 school sites with moderate concentrations (means: 2.6, 32.2, and 5.7 ?g/m3, respectively) were measured from 1996 to 1998. Statistical analysis of the data was performed using components of two different statistical models recently used to predict air pollution levels in comparable settings. Two traffic characteristics, traffic volume and traffic jam percentage, adequately described air pollutant concentrations (R2: 0.76-0.80, P=0.0001). This study shows that air pollutant concentrations can be accurately predicted by two traffic characteristics and that these models compare favorably with other more complex models in the literature

2002-10-01

92

Complete Genome Sequences of Pseudomonas monteilii SB3078 and SB3101, Two Benzene-, Toluene-, and Ethylbenzene-Degrading Bacteria Used for Bioaugmentation.  

Science.gov (United States)

Pseudomonas monteilii SB3078 and SB3101 are benzene-, toluene-, and ethylbenzene-degrading strains used for bioaugmentation in relation to treatment of wastewater contaminated with petrochemical hydrocarbons. Complete genome sequencing of the bioaugmentation strains confirms that they are very closely related (100.0% average nucleotide identity). Both strains contain extensive integration of phage elements, with the main difference being insertion of additional phage elements in the SB3078 genome. PMID:24874689

Dueholm, Morten S; Albertsen, Mads; D'Imperio, Seth; Tale, Vaibhav P; Lewis, Derrick; Nielsen, Per Halkjær; Nielsen, Jeppe Lund

2014-01-01

93

Apparent molar volumes of tri-n-butyl phosphate in C6-C16 n-alkanes, benzene, toluene and tetra chloromethane diluents  

International Nuclear Information System (INIS)

As commercial PUREX diluent is a mixture of various n-alkanes, for development of a group contribution approach to density parameters, apparent molar volume of TBP was experimentally measured in C6-C16 n-alkanes, benzene, toluene and tetra chloromethane. Contrary to observation of Leroy, authors observed a linear dependence of apparent molar volume at infinite dilution with the carbon number of the diluent. In this paper, these results are explained. (author)

2009-01-07

94

Electrodecomposition in subcritical water using o-xylene as a model for benzene, toluene, ethylbenzene, and xylene pollutants.  

Science.gov (United States)

The possibility of the combination of electrolysis and subcritical water as a novel electrolyte was investigated. A stainless steel reactor was used as an undivided electrochemical cell containing platinum as the anode and a stainless steel reactor as the cathode. At first, the effect of temperature on the electrolysis current as the main parameter was studied in a cell containing only pure water and a supporting electrolyte. It was realized that the electrolysis current (and, consequently, the electrolysis efficiency) increased linearly with temperature because of the change in viscosity and other physicochemical properties of subcritical water. As a result, at 553 K the electrolysis efficiency was over 14-fold higher than that under ambient conditions. The possibility of the applicability of the above combined techniques for the decomposition of o-xylene was also followed as a model for benzene, toluene, ethylbenzene, and xylene (BTEX) compounds. The effect of experimental conditions such as the electrolysis duration, the electrolysis voltage, and the temperature of subcritical water was investigated. Several decomposed products were identified. o-Xylene was directly electro-oxidized to 2-methylbenzyl alcohol and consecutively to the other oxidation products. Also, hydroxide ions were oxidized to oxygen molecules, where hydrogen was generated on the cathodic surface. The final oxidation product of the electro-oxidation reaction was identified as carbon dioxide. The results indicate that more than 95% of o-xylene can be decomposed under optimum conditions. PMID:18637665

Asghari, Feridoun Salak; Yoshida, Hiroyuki

2008-08-14

95

Biodegradation and transport of benzene, toluene, and xylenes in a simulated aquifer: comparison of modelled and experimental results  

Science.gov (United States)

Both laboratory experiments and numerical modelling were conducted to study the biodegradation and transport of benzene-toluene-xylenes (BTX) in a simulated semi-confined aquifer. The factors incorporated into the numerical model include advection, hydrodynamic dispersion, adsorption, and biodegradation. The various physico-chemical parameters required by the numerical model were measured experimentally.In the experimental portion of the study, BTX compounds were introduced into the aquifer sand. After the contaminants had been transported through the system, BTX concentrations were measured at 12 equally spaced wells. Subsequently, microorganisms obtained from the activated sludge of a sewage treatment plant and cultured in BTX mixtures were introduced into the aquifer through the 12 sampling wells. The distribution data for BTX adsorption by the aquifer sand form a nonlinear isotherm. The degree of adsorption by the sand varies, depending on the composition of the solute. The degradation time, measured from the time since the bacteria were added to the aquifer until a specific contaminant was no longer detectable, was 35-42 h for BTX. The dissolved oxygen, after degradation by BTX compounds and bacteria, was consumed by about 40-60% in the entire simulated aquifer; thus the aerobic conditions were maintained. This study provides insights for the biodegradation and transport of BTX in aquifers by numerical modelling and laboratory experiments. Experimental and numerical comparisons indicate that the results by Monod degradation kinetics are more accurate than those by the first-order degradation kinetics.

Jean, Jiin-Shuh; Tsai, Ching-Lang; Ju, Shen-Haw; Tsao, Chun-Wen; Wang, Shih-Ming

2002-11-01

96

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

2011-01-01

97

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

Energy Technology Data Exchange (ETDEWEB)

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 V{sub m}{sup E} values have been fitted to the Redlich-Kister polynomial equation, and other volumetric properties such as the partial molar volumes, V{sub i}-bar, the apparent molar volume, V{sub {phi}}{sub i}, and the partial molar excess volumes at infinite dilution, (V{sub i}{sup E}-bar){sup {infinity}}, were calculated over the whole composition range. The Prigogine-Flory-Patterson (PFP) theory and its applicability in predicting V{sub m}{sup E} 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 V{sub m}{sup E} behaviour, the correlation fails.

Sun Yuping; Su Liyan [School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu 214122 (China); Wang Haijun [School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu 214122 (China)], E-mail: wanghj329@hotmail.com

2009-10-15

98

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)

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.

2009-10-01

99

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

2011-01-01

100

Benzene, toluene, ethylbenzene, and xylenes (BTEX) degradation in vadose zone soils during vapor transport: First-order rate constants  

Energy Technology Data Exchange (ETDEWEB)

Many currently available screening-level models for predicting long-term vapor-phase diffusive transport from soils and groundwater to ambient and indoor air neglect degradation mechanisms. In this paper, we summarize ranges of conditions which support aerobic biodegradation of benzene, toluene, ethylbenzene, and xylenes in unsaturated soils, and examine existing experimental information on the range of possible biodegradation rate under these conditions. Mathematical solutions for incorporating degradation mechanisms into vadose-zone vapor transport models an presented for the purpose of consistent definition of degradation rate parameters. Results of previous experiment measurements, and published data on vadose zone BTEX degradation are tabulated as first-order rate parameters and half-life values, with supporting information, including chemical concentration levels, soil characteristic, oxygen levels, and details on the particular experimental scenario. The tabulated first-order rate parameters are presented in a format consistent with the previously mentioned mathematical definitions. Results of this investigation, review, and compilation show that defining a degradation rate based on soil pore water concentration, and presuming that degradation is limited to the pore water phase of the soil matrix, may help explain some observed phenomena, such as reduced degradation for chemicals sorbed to soil, or which are partitioned into a residual hydrocarbon phase. In aerobic soil conditions over broad ranges in soil pore water concentrations, it appears that microbial degradation of BTEX is reasonably described by Monod-type kinetics. At soil pore waters concentrations below approximately 0.2 mg/L, first-order kinetics apply. At and below concentration level, based on available data, a conservative estimate (underpredicting degradation) of a first-order rate constant is 0.4 hr{sup -1}, based on soil pore water concentration.

DeVaull, G.E.; Ettinger, R.A.; Salanitro, J.P.; Gustafson, J.B. [Shell Development Co., Houston, TX (United States)

1997-12-31

 
 
 
 
101

Genetic organization and regulation of a meta cleavage pathway for catechols produced from catabolism of toluene, benzene, phenol, and cresols by Pseudomonas pickettii PKO1.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Plasmid pRO1957 contains a 26.5-kb BamHI restriction endonuclease-cleaved DNA fragment cloned from the chromosome of Pseudomonas pickettii PKO1 that allows P. aeruginosa PAO1c to grow on toluene, benzene, phenol, or m-cresol as the sole carbon source. The genes encoding enzymes for meta cleavage of catechol or 3-methylcatechol, derived from catabolism of these substrates, were subcloned from pRO1957 and were shown to be organized into a single operon with the promoter proximal to tbuE. Deleti...

Kukor, J. J.; Olsen, R. H.

1991-01-01

102

Heterogeneous photocatalytic oxidation of benzene, toluene, cyclohexene and cyclohexane in humidified air. Comparison of decomposition behavior on photoirradiated TiO{sub 2} catalyst  

Energy Technology Data Exchange (ETDEWEB)

Gas-solid heterogeneous photocatalytic decomposition of benzene, toluene, cyclohexane and cyclohexene over TiO{sub 2} was studied at room temperature, and their reactivities were compared. Catalyst deactivation was ascribed to the formation of the carbon deposits on TiO{sub 2} surface, and the formation and decomposition behavior of the carbon deposits affected the decomposition rate. Deactivated TiO{sub 2} catalysts were photochemically regenerated in the presence of water vapor, and the carbon deposits were decomposed to CO{sub x}.

Einaga, Hisahiro; Futamura, Shigeru; Ibusuki, Takashi [National Institute of Advanced Industrial Science and Technology, AIST Tsukuba West, 16-1 Onogawa, Tsukuba, 305-8569 Ibaraki (Japan)

2002-09-01

103

Experimental density, viscosity, interfacial tension and water solubility of ethyl benzene-?-methyl benzyl alcohol–water system  

International Nuclear Information System (INIS)

Highlights: • Properties were measured for MBA (methyl benzyl alcohol)-EB (ethyl benzene)-water. • MBA concentration was found to influence all the properties strongly. • The water solubility, density, and viscosity increased at high MBA concentration. • The interfacial tension decreased sharply at high MBA concentration. • MBA dictates the phase separation and mass transfer of the ternary system. -- Abstract: Density, viscosity, interfacial tension, and water solubility were measured for the (?-methyl benzyl alcohol (MBA) + Ethyl benzene (EB)) system at different concentrations of MBA in contact with water and sodium hydroxide solution (0.01 mol · kg?1) as aqueous phases. The properties were measured to identify the component which plays a governing role in changing the physical properties relevant to mass transfer and phase separation of the ternary system. The concentration of MBA was found to be the major factor influencing all the properties. The water solubility, the density, and the viscosity increased notably at higher concentrations of MBA; while, the interfacial tension decreased strongly. The use of 0.01 mol · kg?1 NaOH as an aqueous phase resulted in a decrease of the interfacial tension and a minor decrease in the water solubility. The density data were correlated using a quadratic mixing rule to describe the influence of concentration at any temperature. The viscosity data are correlated using the Nissan and Grunberg and Katti-Chaudhri equations. The Szyzkowski’s equation was used to correlate the interfacial tension data. The water solubility data were described using an exponential relationship. All the correlations described the experimental physical property data adequately

2013-08-01

104

090317 Toluene SGV publication final  

…contain benzene at levels of up to 0.01 per cent, while industrial grade toluene may contain benzene at levels of up to 25 per cent (IPCS, 1985). Toluene is a commercially important chemical produced throughout the world in enormous quantities (IPCS, 1985). The annual consumption of toluene across the…

105

Heterogeneous adsorption and catalytic oxidation of benzene, toluene and xylene over spent and chemically regenerated platinum catalyst supported on activated carbon  

Science.gov (United States)

The heterogeneous adsorption and catalytic oxidation of benzene, toluene and o-xylene (BTX) over the spent platinum catalyst supported on activated carbon (Pt/AC) as well as the chemically treated spent catalysts were studied to understand their catalytic and adsorption activities. Sulfuric aqueous acid solution (0.1N, H 2SO 4) was used to regenerate the spent Pt/AC catalyst. The physico-chemical properties of the catalysts in the spent and chemically treated states were analyzed by using nitrogen adsorption-desorption isotherm and elemental analysis (EDX). The gravimetric adsorption and the light-off curve analysis were employed to study the BTX adsorption and oxidation on the spent catalyst and its modified Pt/AC catalysts. The experimental results indicate that the spent Pt/AC catalyst treated with the H 2SO 4 aqueous solution has a higher toluene adsorption and conversion ability than that of the spent Pt/AC catalyst. A further studies of H 2SO 4 treated Pt/AC catalyst on their catalytic and heterogeneous adsorption behaviours for BTX revealed that the activity of the H 2SO 4 treated Pt/AC catalyst follows the sequence of benzene > toluene > o-xylene. The adsorption equilibrium isotherms of BTX on the H 2SO 4 treated Pt/AC were measured at different temperatures ranging from 120 to 180 °C. To correlate the equilibrium data and evaluate their adsorption affinity for BTX, the two sites localized Langmuir (L2m) isotherm model was employed. The heterogeneous surface feature of the H 2SO 4 treated Pt/AC was described in detail with the information obtained from the results of isosteric enthalpy of adsorption and adsorption energy distributions. Furthermore, the activity of H 2SO 4 treated Pt/AC about BTX was found to be directly related to the Henry's constant, isosteric enthalpy of adsorption and adsorption energy distribution functions.

Shim, Wang Geun; Kim, Sang Chai

2010-06-01

106

Induction of hsp70, hsp60, hsp83 and hsp26 and oxidative stress markers in benzene, toluene and xylene exposed Drosophila melanogaster: Role of ROS generation  

International Nuclear Information System (INIS)

Exposure to benzene, toluene and xylene in the human population may pose a health risk. We tested a working hypothesis that these test chemicals cause cellular toxicity to a non-target organism, Drosophila melanogaster. Third instar larvae of D. melanogaster transgenic for hsp70, hsp83 and hsp26 and Oregon R+ strain were exposed to 1.0-100.0 mM benzene, toluene and xylene for 2-48 h to examine the heat shock proteins (hsps), ROS generation, anti-oxidant stress markers and developmental end points. The test chemicals elicited a concentration- and time-dependent significant (p hsp83 ? hsp26 as evident by ?-galactosidase activity after 24 h. RT-PCR amplification studies in Oregon R+ larvae revealed a similar induction pattern of these genes along with hsp60 in the order of hsp70 > hsp60 > hsp26 ? hsp83. Under similar experimental conditions, a significant induction of ROS generation and oxidative stress markers viz. superoxide dismutase, catalase, glutathione S-transferase, thioredoxin reductase, glutathione, malondialdehyde and protein carbonyl content was observed. Sub-organismal response was propagated towards organismal response i.e., a delay in the emergence of flies and their reproductive performance. While hsp70 was predominantly induced in the organism till 24 h of treatment with the test chemicals, a significant or insignificant regression of Hsp70 after 48 h was concurrent with a significant induction (p hsp83 ? hsp26 in comparison to the former. A significant positive correlation was observed between ROS generation and these hsps in the exposed organism till 24 h and a negative correlation between ROS generation and hsp70 in them after 48 h indicating a modulatory role of ROS in the induction of hsps. The study suggests that among the tested hsps, hsp70 may be used as an early bioindicator of cellular toxicity against benzene, toluene and xylene and D. melanogaster as an alternative animal model for screening the risk posed by environmental chemicals

2009-03-01

107

Health Risk Assessment of Ambient Air Concentrations of Benzene, Toluene and Xylene (BTX) in Service Station Environments  

Science.gov (United States)

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

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

2014-01-01

108

A preliminary study on ambient levels of carbonyls, benzene, toluene and xylene in the south-west of the Iberian Peninsula (Huelva coast), Spain.  

Science.gov (United States)

We report the first observations of volatile organic compound (VOC) concentrations, including aldehydes, in the coastal, industrial area of Huelva near the Doñana National Park (south-west of the Iberian Peninsula). The periods studied were July-September 2008 and February-November 2009. Formaldehyde, acetaldehyde, acetone, propanal, benzene, toluene and m/p-xylenes were identified and quantified. Acetone and formaldehyde were the most abundant carbonyls, followed by acetaldehyde and propanal. Maximum and minimum values for all these compounds in the period of measurement, and their relationship with meteorological parameters or influence of anthropogenic or biogenic emissions, are analysed. Finally, different concentration ratios and correlations were calculated to assess the effect of the anthropogenic or biogenic processes on the observed VOC levels. PMID:23530343

Villanueva, Florentina; Notario, Alberto; Adame, José Antonio; Millán, María Cruz; Mabilia, Rosanna; Albaladejo, José

2013-01-01

109

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 < 1?g level and employed for the analysis of several environmental and biological standard Reference Materials from NIST (USA), IAEA (Vienna) and NIES (Japan). (author) 39 refs.; 4 figs.; 4 tabs

1994-11-01

110

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

International Nuclear Information System (INIS)

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

2006-08-01

111

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

Science.gov (United States)

Consecutive reactions of adducts, resulting from OH radicals and aromatics, with the tropospheric scavenger molecules O2, NO and NO2 have been studied for benzene, 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.

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

2006-08-01

112

Isotope effects in aqueous systems. 13. The hydrophobic interaction. Some thermodynamic properties of benzene/water and toluene/water solutions and their isotope effects  

International Nuclear Information System (INIS)

Henry's law constants, K/sub H/ = K_0 + K"1X, have been measured as a function of concentration for the water-rich and benzene-rich solutions C"6H"6/H"2O and C"6H"6/D"2O and for the water-rich solutions C"6D"6/H"2O and C"6D"6/D"2O at several temperatures The constants K_0 and K"1 are sensitive to temperature and to isotopic label. The vapor pressure results have been supplemented with measurements of the apparent molar volumes of the solutions listed above, as well as for H"2O"- and D"2O-rich solutions of toluene and deuteriotoluene, and with determinations of the solubilities and solubility isotope effects of the toluene solutions. The data have been interpreted in the context of the theory of isotope effects in condensed-phase systems. That analysis indicates that a significant dynamical vibrational coupling between solute and solvent normal modes occurs in these solutions. The result is of interest particularly as it pertains to models of the hydrophobic interaction

1982-04-29

113

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

2013-11-01

114

Petroleum hydrocarbon toxicity in vitro: effect of n-alkanes, benzene and toluene on pulmonary alveolar macrophages and lysosomal enzymes of the lung  

Energy Technology Data Exchange (ETDEWEB)

The in vitro effects of straight chain alkanes (nC6-nC10), benzene and toluene on pulmonary alveolar macrophages (PAM) of rats and rabbits was studied. The concentrations used ranged from 0.02 to 1.0 mM. All hydrocarbons used in the study were cytotoxic to isolated cultured PAM cells in a dose-dependent manner. The LC50 for these hydrocarbons towards rat PAM cells was estimated to be 1.0 mM for nC8, 2 mM for nC7, 5 mM for nC9 and 10 mM for nC6, nC10, benzene and toluene. Rabbit PAM cells were more sensitive to the hydrocarbons, resulting in an LC50 half that for rat PAM cells. Hydrocarbons also caused extracellular release of the lysosomal enzymes cathepsin D (EC 3.4.23.5) and cathepsin B (EC 3.4.22.1) in a manner corresponding with cell damage. There was more cathepsin D activity released from cells than cathepsin B. In addition, hydrocarbons also caused the release of cathepsin B and D from isolated lysosomes, and there was 10-15% more enzyme activity released in the culture medium of lysosomes exposed to concentrations of 0.5 and 1.0 mM compared to PAM cell cultures of either rats or rabbits. Hydrocarbons also caused loss of cell respiration and stimulated a dose-dependent and a time-dependent increase in lipid peroxidation. The two alkanes nC7 and nC8 caused the greatest increase in lipid peroxidation and the greatest loss of cell respiration. The results indicate that there is a relationship between chain length of alkanes and their cytotoxicity to PAM cells. The results also demonstrate a good correlation between decreased cell viability, increased lysosomal enzyme release, decreased cell respiration and increased lipid peroxidation in response to the hydrocarbons.

Suleiman, S.A.

1987-04-01

115

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The formation of halogen bonded complexes formed between the trifluorohalomethanes CF3Cl, CF3Br and CF3I and the Lewis bases benzene and toluene at temperatures below 150K was investigated using FTIR and Raman spectroscopy. Experiments using liquid krypton as solvent show that for both CF3Br and CF3I substantial fractions of the monomers can be involved in 1:1 complexes. In addition, weak absorptions illustrating the formation of 2:1 complexes between CF3I and benzene are observed. Using spec...

Nick Nagels; Dieter Hauchecorne; Herrebout, Wouter A.

2013-01-01

116

090323 Benzene SGV final  

…hydrodealkylation (ATSDR, 2007). The major impurities found in commercial benzene are toluene, xylene, phenol, thiophene, carbon disulphide, acetylnitrile and pyridine (ATSDR, 2007). Benzene is used throughout the world in enormous quantities. Other than its use as an additive to petrol, the vast majority of benzene…

117

Assessing air quality inside vehicles and at filling stations by monitoring benzene, toluene, ethylbenzene and xylenes with the use of semipermeable devices.  

Science.gov (United States)

BTEX (benzene, toluene, ethylbenzene, and xylenes) were used as target molecules to evaluate the quality of air inside motor vehicles and near filling stations, using semipermeable membrane devices (SPMDs) as low-cost passive sampling devices. A direct, fast, simple methodology based on the use of headspace-gas chromatography-mass spectrometry detection (HS-GC-MS) was developed for BTEX determinations, without any sample pre-treatment. SPMDs (25.4 cm2 surface, filled with 100 microL triolein) were employed as static samplers. After the selected deployment time, the SPMDs were heated inside a HS vial at 150 degrees C for 20 min and BTEX compounds were determined by GC-MS in selected ion monitoring (SIM) mode in less than 12 min. The proposed method provides limits of detection of less than 1 ng SPMD(-1) for all compounds studied; which is equivalent to 0.3-8 ng m(-3) in air for a deployment time of 24 h, and to 9-200 microg m(-3) for 10 min time, as a function of the compound considered. Using sampling times of around 24 h, concentrations from 0.2 to 145 microg m(-3) were measured inside motor vehicles. For exposure times from 2 to 40 min, concentrations of BTEX ranging from 0.03 to 79 mg m(-3) were measured at filling stations, especially during refueling of vehicles with gasoline. PMID:17531831

Esteve-Turrillas, Francesc A; Pastor, Agustín; de la Guardia, Miguel

2007-06-12

118

Preparation and application of carbon nanotubes/poly(o-toluidine) composite fibers for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes.  

Science.gov (United States)

A novel nanocomposite coating of poly(o-toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless-steel wire. The applicability of the fiber was assessed for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o-toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid-phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03-0.06 ?g/L. The method showed linearity in the range of 0.5-300 ?g/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 ?g/L concentration level (n = 5) using a single fiber were 1.2-5.2 and 3.2-7.5%, respectively. The fiber-to-fiber RSD (%; n = 3) at 5 ?g/L was 6.1-9.2%. PMID:24106154

Behzadi, Mansoureh; Noroozian, Ebrahim; Mirzaei, Mohammad

2013-11-01

119

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

Science.gov (United States)

In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co3O4 nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC-MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared. PMID:24725745

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

2014-04-25

120

(E)-2-[4-(Di-ethyl-amino)-styr-yl]-1-methyl-quinolin-1-ium 4-chloro-benzene-sulfonate monohydrate.  

Science.gov (United States)

The asymmetric unit of the title hydrated salt, C22H25N2 (+)·C6H4ClO3S(-)·H2O, comprises two 2-[4-(di-ethyl-amino)-styr-yl]-1-methyl-quinolin-1-ium cations, two 4-chloro-benzene-sul-fon-ate anions and two solvent water mol-ecules. One ethyl group of both cations displays disorder over two positions in a 0.659?(2):0.341?(2) ratio in one mol-ecule and in a 0.501?(2):0.499?(2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893?(7):0.107?(7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57?(18)° in one cation and 14.4?(2)° in the other. In the crystal, cations, anions and water mol-ecules are linked into chains along the [010] direction by O-H?Osulfonate hydrogen bonds, together with weak C-H?Osulfonate and C-H?Cl inter-actions. The cations are stacked by ?-? inter-actions, with centroid-centroid distances in the range 3.675?(2)-4.162?(3)?Å. PMID:24826116

Chantrapromma, Suchada; Kaewmanee, Narissara; Boonnak, Nawong; Quah, Ching Kheng; Fun, Hoong-Kun

2014-04-01

 
 
 
 
121

Determination of gas-phase produced ethyl parathion and toluene 2,4-diisocyanate by ion mobility spectrometry, gas chromatography and liquid chromatography.  

Science.gov (United States)

Ethyl parathion and toluene 2,4-diisocyanate (2,4-TDI) vapors were generated using a vapor generation system that was designed for the evaporation of liquid samples at known flow rates. The vapor generation of parathion and 2,4-TDI posed a challenge because of their low volatility and tendency to absorb into surfaces of the vapor generation system. Experimental concentration of parathion was determined using gas chromatography-mass spectrometry (GC-MS). 2,4-TDI was derivatized with 1-(2-pyridyl)piperazine to urea derivative which concentration was analyzed using high performance liquid chromatography (HPLC). In addition, in combination with vapor generator, aspiration IMS was used for monitoring ion mobility cell (IMCell) and semiconductor cell (SCCell) responses to parathion and 2,4-TDI vapors. The chromatographic results correlated well with the IMCell response data, showing high specificity of IMS to parathion and 2,4-TDI. The concentrations of parathion and 2,4-TDI at the detection limit of IMS were significantly lower than IDLH threshold values of parathion or 2,4-TDI, demonstrating high sensitivity of IMS to both compounds. The IMS patterns of both chemicals and the influence of humidity on IMCell and SCCell sensitivity were analyzed. PMID:19071713

Nousiainen, Marjaana; Peräkorpi, Kaleva; Sillanpää, Mika

2007-05-15

122

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

International Nuclear Information System (INIS)

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

2006-11-01

123

Excess and deviation properties for the binary mixtures of methylcyclohexane with benzene, toluene, p-xylene, mesitylene, and anisole at T = (298.15, 303.15, and 308.15) K  

International Nuclear Information System (INIS)

Experimental data on density, viscosity, and refractive index at T = (298.15, 303.15, and 308.15) K, while speed of sound values at T = 298.15 K are presented for the binary mixtures of (methylcyclohexane + benzene), methylbenzene (toluene), 1,4-dimethylbenzene (p-xylene), 1,3,5-trimethylbenzene (mesitylene), and methoxybenzene (anisole). From these data of density, viscosity, and refractive index, the excess molar volume, the deviations in viscosity, molar refraction, speed of sound, and isentropic compressibility have been calculated. The computed values have been fitted to Redlich-Kister polynomial equation to derive the coefficients and estimate the standard errors. Variations in the calculated excess quantities for these mixtures have been studied in terms of molecular interactions between the component liquids and the effects of methyl and methoxy group substitution on benzene ring

2006-12-01

124

Thermodynamics of fuels with a bio-synthetic component (IV): (Vapor + liquid) equilibrium data for the ternary mixture (ethyl 1,1-dimethylethyl ether + 1-hexene + toluene) at T = 313.15 K  

Energy Technology Data Exchange (ETDEWEB)

The paper reports experimental p-x data for the ternary system (ethyl 1,1-dimethylethyl ether + 1-hexene + toluene) at T = 313.15 K. The ether, synthesized from ethanol of biological origin, increases the interest of this compound as an additive for gasolines. An isothermal total pressure cell was used for the measurements. Data reduction by Barker's method provides correlations for G{sup E}, using Wilson, NRTL, UNIQUAC models and the Wohl expansion for the ternary system and the calculation of the vapor phase composition. Good results are obtained for the correlation by all the models.

Villamanan, Rosa M. [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: rvillama@dce.uva.es; Segovia, Jose J. [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: josseg@eis.uva.es; Carmen Martin, M. [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: mcmg@eis.uva.es; Vega-Maza, David [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: davveg@eis.uva.es; Chamorro, Cesar R. [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: cescha@eis.uva.es; Villamanan, Miguel A. [Research Group TERMOCAL-Thermodynamics and Calibration University of Valladolid, Paseo del Cauce s/n, 47011 Valladolid (Spain)], E-mail: miguel.villamanan@eis.uva.es

2009-02-15

125

Improved process disproportionates toluene at Fina's refinery in Port Arthur, Tex  

Energy Technology Data Exchange (ETDEWEB)

Fina Oil and Chemical Co. has increased its aromatics production profitability by the installation of an improved toluene disproportionation unit, called the Fina T2BX process, at its Port Arthur, Tex, refinery. The improved process incorporates a proprietary catalyst to disproportionate toluene into benzene and xylenes (mixed para, meta, ortho xylenes, and ethylbenzene). During the past 10 years, the aromatics market has consistently shown a difference between the prices of benzene, toluene, and xylenes. Benzene prices have been above toluene, while xylenes have been equal to or greater than toluene. This pricing scenario favors the conversion of toluene to either benzene alone or a mixture of benzene and xylenes. Other factors, such as a captive market for benzene or xylenes, can increase the value of converting excess toluene to more useful and profitable benzene or xylenes. Two processes are currently available for these conversions. These are hydrodealkylation of toluene and toluene disproportionation, or transalkylation.

Menard, K.P.

1987-03-16

126

(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

2007-08-01

127

(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  

Energy Technology Data Exchange (ETDEWEB)

(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.

Chen Dongchu [College of Chemistry and Chemical Engineering, Central South University, Changsha 411083 (China)]. E-mail: dcchen@hnust.edu.cn; Ye Hongqi [College of Chemistry and Chemical Engineering, Central South University, Changsha 411083 (China); Wu Hao [College of Chemistry and Chemical Engineering, Central South University, Changsha 411083 (China)

2007-08-15

128

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

2007-01-01

129

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

130

090323 Benzene SGV final  

…2007). It is slightly soluble in water but is easily miscible with most organic solvents (IPCS, 1993; ATSDR, 2007; ECB, 2007). Benzene, toluene, ethylbenzene and xylene are often referred to collectively as BTEX because they have closely related chemical structures, and have similar fate and transport…

131

Prevention of occupational diseases due to benzene, toluene, xylene and ethylbenzene. Praevention beruflich bedingter Gesundheitsschaeden durch Benzol, Toluol, Xylole und Ethylbenzol  

Energy Technology Data Exchange (ETDEWEB)

The aim of the study was to create the preconditions for medical checks on persons professionally exposed to BTX aromatics and to re-evaluate the previous monitoring practice in order to derive an appropriate surveillance concept. To monitor persons professionally exposed to harmful materials three conditions must be fulfilled: valid analytical methods to determine the aromatic hydrocarbons in the air at work as well as in biological material and their metabolites in urine. To that end adequate methods of chemical analysis and diagnosis were developed, suitable biological parameters to assess the internal exposure. This meant, on the one hand, that the suitability of the monitoring parameters used so far had to be verified and, on the other hand, that new and more informative biological indicators of aromatic-hydrocarbon exposure had to be sought after. For this purpose refined technical analytical methods were tried in order to investigate the metabolic paths of alkyl benzene that have so far evaded examination - limits or standard values to evaluate the results of the biological monitoring. Checks on professionally exposed groups establishing a relation between the outer and internal exposure to noxious agents were an approach to the derivation of such limits. Furthermore the aim of the investigation consisted in resolving contradictory opinions on the suitability of different biological material - especially blood and urine - for medical checks, in order to give a more precise definition of the different information to be gained from individual indicators in relation to the biological matrix examined, and thus to make use of it for a monitoring concept. Finally the attempt was made to assess the value of each of the two measuring strategies: ambient and biological monitoring, within occupational hygiene.

Angerer, J.

1983-01-01

132

Knoevenagel condensation of aromatic aldehydes with ethyl 4-chloro-3-oxobutanoate in ionic liquids  

Energy Technology Data Exchange (ETDEWEB)

Knoevenagel condensations of aromatic aldehydes with ethyl 4-chloro-3-oxobutanoate catalyzed by morpholine/acetic acid were carried out in ionic liquids to give ethyl 2-chloroacetyl-3-arylpropenoates in 44-84% yield after 0.5 to 2 h at room temperature (25-28 deg C). These conditions represent a greener protocol for the Knoevenagel condensation than those using refluxing benzene or toluene as solvent. Aromatic aldehydes having aryl groups 4-chlorophenyl, 4-methoxyphenyl, 2-thiofuranyl, 2-furanyl, phenyl and 3,4-methylenedioxyphenyl gave (E)/(Z) diastereomeric ratios of products from 56/44 to 85/15. The two isomers of each compound were separately isolated and characterized. The structure of the (E)-isomer of ethyl 2-chloroacetyl-3-(3',4'methylenedioxyphenyl) propenoate was determined by X-ray crystallography and an unequivocal methodology of (E)/(Z)-structural analysis by {sup 13}C NMR (nuclear magnetic resonance) is presented. (author)

Paula, Bruno R.S. de; Zampieri, Davila S.; Rodrigues, Jose Augusto R.; Moran, Paulo J.S., E-mail: moran@iqm.unicamp.br [Institute of Chemistry, University of Campinas, Campinas-SP (Brazil); Zukerman-Schpector, Julio [Department of Chemistry, Federal University of Sao Carlos, SP (Brazil); Tiekink, Edward R.T. [Department of Chemistry, University of Malaya, Kuala Lampur (Malaysia)

2012-05-15

133

Toulouse urban area aromatic volatile organic compounds: benzene, toluene, xylenes (BTX) and nitrogen dioxide distribution study; Etude de la distribution atmospherique de composes organiques volatils aromatiques: benzene, toluene, xylenes (BTX) et du dioxyde d'azote sur l'agglomeration toulousaine  

Energy Technology Data Exchange (ETDEWEB)

The Observatoire regional de l'air en Midi-Pyrenees (ORAMIP) - a French regional atmospheric pollution measurements network - is in charge of air quality observation over the Toulouse urban area. Air quality measurements are done daily, using almost 80 analysers spread in more than thirty stations. Regulation for atmospheric pollution major indicators (ozone, nitrogen dioxide, sulphur dioxide...) has constantly evolved, and some compounds, e.g. benzene, have been regimented only very soon. ORAMIP, in partnership with the Ecole Nationale Superieure de Chimie de Toulouse (ENSCT) Chemistry Energy and Environment Laboratory, has carried out background BTX average concentrations measurements and evaluation by passive sampling study over Toulouse urban agglomeration. This study was carried out during two 1999 springtime and summer periods, over about sixty sites. These points were chosen among those of the NO{sub 2} measurements 1991-1992 and 1996-1997 ORAMIP campaigns. During the two periods, wind conditions were similar but it happened to rain during the first period. Although NO{sub 2} is decomposed in water, benzene, very few soluble, has some concentrations very close from one period to another. BTX pollution over Toulouse has in majority been produced by motor vehicle exhaust gases. The benzene average amount over the two Toulouse campaigns is equal to 2,2 {mu}g/m{sup 3}, very close to the French quality focus, and well under the average value of 5 {mu}g/m{sup 3} recommended by EEC countries, knowing that those regulations are given for a whole year. Moreover, 'P98/annual average' Khuner reports for 1999 NO{sub 2} settled urban captors and for punctual campaigns with passive samplers are similar (2,7 and 2). This study allowed us to show that BTX and NO{sub 2} in Toulouse atmosphere result essentially from exhaust gases: It would be important to measure benzene over annual periods, in order to know its exact values over such a period, and to observe its potential seasonal variations. Moreover, as far as the benzene limit value contained in gasoline went from 5 % to 1 % since 2000 January 1, it would be interesting to carry out again a passive sampling study to observe possible differences pointed out with such a reform. (authors)

Meybeck, M.; Della Massa, J.P. [Observatoire Regional de l' Air en Midi Pyrenees, ORAMIP, 31 - Colomiers (France); Simon, V.; Grasset, E.; Torres, L. [Ecole Nationale Superieure de Chimie, 31 - Toulouse (France)

2001-01-01

134

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

1994-07-11

135

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

2013-03-01

136

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)

Summary 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.

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

2013-01-01

137

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.

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

2013-01-01

138

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

2013-01-01

139

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

International Nuclear Information System (INIS)

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

2007-12-01

140

(Liquid + liquid) equilibria in the binary systems (aliphatic, or aromatic hydrocarbons + 1-ethyl-3-methylimidazolium ethylsulfate, or 1-butyl-3-methylimidazolium methylsulfate ionic liquids)  

Energy Technology Data Exchange (ETDEWEB)

(Liquid + liquid) equilibria of 14 binary systems composed of n-hexane, n-heptane, benzene, toluene, o-xylene, m-xylene, or p-xylene and 1-ethyl-3-methylimidazolium ethylsulfate, [emim]EtSO{sub 4}, or 1-butyl-3-methylimidazolium methylsulfate, [bmim]MeSO{sub 4}, ionic liquids have been done in the temperature range from (293.2 to 333.2) K. The solubility of aliphatic is less than those of the aromatic hydrocarbons. In particular, the solubility of hydrocarbons in both ionic liquids increases with the temperature in the order n-heptane < n-hexane < m-xylene < p-xylene < o-xylene < toluene < benzene. Considering the high solubility of aromatics and the low solubility of aliphatic hydrocarbons as well as totally immiscibility of the ionic liquids in all hydrocarbons, these new green solvents may be used as potentials extracting solvents for the separation of aromatic and aliphatic hydrocarbons.

Garcia, Julian, E-mail: jgarcia@quim.ucm.e [Department of Chemical Engineering, Complutense University of Madrid, E-28040 Madrid (Spain); Torrecilla, Jose S.; Fernandez, Adela; Oliet, Mercedes; Rodriguez, Francisco [Department of Chemical Engineering, Complutense University of Madrid, E-28040 Madrid (Spain)

2010-01-15

 
 
 
 
141

(Liquid + liquid) equilibria in the binary systems (aliphatic, or aromatic hydrocarbons + 1-ethyl-3-methylimidazolium ethylsulfate, or 1-butyl-3-methylimidazolium methylsulfate ionic liquids)  

International Nuclear Information System (INIS)

(Liquid + liquid) equilibria of 14 binary systems composed of n-hexane, n-heptane, benzene, toluene, o-xylene, m-xylene, or p-xylene and 1-ethyl-3-methylimidazolium ethylsulfate, [emim]EtSO4, or 1-butyl-3-methylimidazolium methylsulfate, [bmim]MeSO4, ionic liquids have been done in the temperature range from (293.2 to 333.2) K. The solubility of aliphatic is less than those of the aromatic hydrocarbons. In particular, the solubility of hydrocarbons in both ionic liquids increases with the temperature in the order n-heptane < n-hexane < m-xylene < p-xylene < o-xylene < toluene < benzene. Considering the high solubility of aromatics and the low solubility of aliphatic hydrocarbons as well as totally immiscibility of the ionic liquids in all hydrocarbons, these new green solvents may be used as potentials extracting solvents for the separation of aromatic and aliphatic hydrocarbons.

2010-01-01

142

Monohydroxylation of phenol and 2,5-dichlorophenol by toluene dioxygenase in Pseudomonas putida F1.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pseudomonas putida F1 contains a multicomponent enzyme system, toluene dioxygenase, that converts toluene and a variety of substituted benzenes to cis-dihydrodiols by the addition of one molecule of molecular oxygen. Toluene-grown cells of P. putida F1 also catalyze the monohydroxylation of phenols to the corresponding catechols by an unknown mechanism. Respirometric studies with washed cells revealed similar enzyme induction patterns in cells grown on toluene or phenol. Induction of toluene ...

Spain, J. C.; Zylstra, G. J.; Blake, C. K.; Gibson, D. T.

1989-01-01

143

Reactions of solid benzene with accelerated CH2+ ions  

International Nuclear Information System (INIS)

Carbene (14CH2+) ions, kinetic energy 10 eV, were impinged on solid benzene at -1960C and the product yields determined. These were compared with the results obtained when bare carbon (14C+) ions were used. In addition, the radioactivity distribution between the ring and the methyl group of the toluene product was established. Results support the earlier suggestion that carbene is an important intermediate in the benzene-to-toluene and benzene-to-cycloheptatriene syntheses. Surprisingly, labeled benzene was found to result from irradiating benzene with the 14CH2+ beam

1976-08-12

144

Gamma radiolysis of toluene and deuterated toluenes: Pt. 1; Isotopic exchange  

Energy Technology Data Exchange (ETDEWEB)

The {gamma} radiolysis of liquid toluene and toluene-d{sub 8} was studied at 50degC. For toluene, product yields were 0.14 molecules of hydrogen, 0.006 of methane, 0.090 of biphenyl and 0.9 of ''polymer'' for each 100 eV absorbed. For toluene-d{sub 8}, these yields are lower by a factor of two to three. Radiolysis of mixtures of toluene and toluene-d{sub 8} shows a disproportionately high decomposition of the light toluene, suggesting that energy initially absorbed in toluene-d{sub 8} transfers to toluene before decomposition occurs. Deuterium tracer studies indicate that about 14% of the hydrogen arises from unimolecular processes, whereas none of the methane or bibenzyl arises in this way. Studies using an electron scavenger, ethyl bromide, and a proton scavenger, ethanol, showed that the hydrogen yield did not likely have long-lived electrons or ions as precursors. Thus the energy transfer from toluene-d{sub 8} to toluene is probably by direct excitation transfer, and not by charge transfer. (author).

Sagert, N.H.; MacFarlane, R.; Kremers, W. (Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Nuclear Research Establishment)

1991-01-01

145

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

Energy Technology Data Exchange (ETDEWEB)

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

Gonzalez-Olmos, R. [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Avinguda Paisos Catalans 26, Campus Sescelades, 43007 Tarragona (Spain)], E-mail: rafael.gonzalez@urv.net; Iglesias, M. [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Avinguda Paisos Catalans 26, Campus Sescelades, 43007 Tarragona (Spain)

2007-12-15

146

Low cost benzene reduction for RFG  

Energy Technology Data Exchange (ETDEWEB)

In the typical refinery benzene comes from several sources including: light straight run gasoline, isomerate, reformate, hydrocrackate, FCC gasoline, and coker gasoline. However the benzene from the reformer usually represents 50--80% of the total. As a result the reformate is the natural place to focus benzene reduction. The benzene content of the reformate is normally in the range of 2.5 to 8 volume %. The higher benzene concentrations occur in high pressure reformers due to hydrodealkylation of toluene and heavier alkylbenzenes. Benzene can be reduced in the reformate by removing benzene precursors such as cyclic C{sub 6}`s in the reformer feed. However, hydrodealkylation of other aromatics in the reformer will still leave a reformate benzene content of 1 to 1.5 volume %. More complete control of benzene can be achieved by removing it from the reformate rather than by treating the reformer feed stream. The paper describes the conventional benzene saturation process and the CDHydro process, which combines fractionation with hydrogenation. Capitalized costs are summarized. Refiners can maintain gasoline compositions with high aromatic contents by using the flexibility offered by the Complex Model. CDHydro provides a very cost effective method of benzene control for the refiner. Benzene reduction targets for both 1995 and 2000 are easily met. CDHydro can provide much higher benzene removal than required by the models, thus giving the refiner valuable options for averaging and trading credits.

Rock, K.L. [CDTECH, Houston, TX (United States)

1995-09-01

147

Toluene 3-Monooxygenase of Ralstonia pickettii PKO1 Is a para-Hydroxylating Enzyme  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oxygenases are promising biocatalysts for performing selective hydroxylations not accessible by chemical methods. Whereas toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 hydroxylates monosubstituted benzenes at the para position and toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 hydroxylates at the ortho position, toluene 3-monooxygenase (T3MO) of Ralstonia pickettii PKO1 was reported previously to hydroxylate toluene at the meta position, producing primarily m-creso...

Fishman, Ayelet; Tao, Ying; Wood, Thomas K.

2004-01-01

148

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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 petroleum 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.

Elaine A. A. F. Gobato

2001-04-01

149

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 SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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 det [...] ermination of the volatile components in drinking water. Benzene, Toluene and Xylene (BTX) are important compounds usually present in drinking water, from contamination by petroleum 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.

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

150

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

151

Bis[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carb-oxy-lic acid] 2,5-dicarb-oxy-benzene-1,4-di-carboxyl-ate octa-hydrate.  

Science.gov (United States)

The asymmetric unit of the title compound, 2C(14)H(18)N(5)O(3) (+)·C(10)H(5)O(8) (2-)·8H(2)O, contains one [H(2)ppa](+)cation, one half of an [H(2)btec](2-) anion (H(4)btec = 1,2,4,5-benzene-tetra-carb-oxy-lic acid and Hppa = 8-ethyl-5-oxo-2-piperazin-1-yl-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carb-oxy-lic acid) that is completed by inversion symmetry and four water mol-ecules. In the crystal, the mol-ecules are connected by inter-molecular hydrogen-bonding inter-actions and ?-? stacking between the benzene rings of the [H(2)btec](2-) anion and the pyrimidine rings of the [H(2)ppa](+) cation [centroid-centroid distance = 3.597?(3)?Å], generating a three-dimensional supra-molecular structure. PMID:21754029

Zhang, Guang-Ju; He, Jiang-Hong; Yan, Shi-Wei; Ye, Zhong-Li; Xin, Guang-Hua

2011-04-01

152

Incineration of toluene and chlorobenzene in a laboratory incinerator  

Energy Technology Data Exchange (ETDEWEB)

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

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

1992-01-01

153

Benzene complexes in cyclopentadienylcobalt(I) reaction systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Photolysis of (C5H5)Co(CO)2 in an aromatic solvent, such as benzene, toluene or s-mesitylene generates the corresponding (C5H5)Co(arene) and (C5H5)Co(arene)2 complexes. The benzene complex (C5H5)Co(C6H6) reacts with 2-butyne to form the hexamethyl benzene derivative (C5H5)Co(C6(CH3)6) but does not catalyze th...

Lee, Wai-sun; Koola, Johnson D.; Brintzinger, Hans-herbert

1981-01-01

154

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

155

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)

2007-06-01

156

Interaction of ethyl radicals with toluene as the main route to formation of aluminium-free products in the reaction of (C2H5O)5AlC2H5 + XeF2  

International Nuclear Information System (INIS)

The mechanism of redox interaction of organoaluminium compounds (OAC) with XeF2 followed by chemiluminescence and the effect of the solvent nature on this interaction are investigated. It is shown that, when using toluene as a solvent, the reaction products not containing aluminium, are formed at the expense of alkyl radical interaction with the solvent. A free-radical mechanism of the reaction of OAC with XeF2 is established by data on chemiluminescence inhibition and gas liberation. Chemiluminescence followed by liberation of gaseous xenon is discovered during inhibitor (galvinoxyl) interaction with XeF2

1987-01-01

157

Occupational exposure to benzene in the shoe industry  

Energy Technology Data Exchange (ETDEWEB)

In order to determine the possible actual exposure to benzene in the shoe industry from industrially used solvents, glues, and paints containing benzene as a nondeclared constituent, phenol in urine and benzene in blood, as indices of internal exposure to benzene, were measured in workers (N = 33). Since toluene, in contrast to benzene, is declared as a constituent in several glues, toluene in the blood of workers was also analysed. All analyses were performed using gas chromatography. Urine samples were collected on Monday morning (MI) before work and on Wednesday (WI) before and (WII) after work. Venous blood samples were taken on Wednesday only, 1/2 hour after work. There was no difference in the phenol concentrations of MI and WI, while the phenol concentration of WII was about twice as high as that in WI. In all blood samples, benzene was found, as well as toluene, which was about four times higher in comparison with benzene. A correlation (r = 0.465; p less than .01) was found between the difference in pre- and postshift phenol concentrations (WII-WI) in urine and the benzene concentrations in blood. The results presented show that a trace amount of benzene, which is often not declared as a constitutent in industrially used chemicals, could be a source of marked exposure to benzene. It can also be concluded that changes in phenol in urine (if preshift and postshift samples are taken) might be a sufficiently sensitive parameter to assess exposure to benzene even when other data concerning the presence of benzene in the working atmosphere are not available.

Karacic, V.; Skender, L.; Prpic-Majic, D.

1987-01-01

158

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

159

Poly[ethyl­enediaminium [di-?-aqua-(?6-benzene-1,2,4,5-tetra­carboxyl­ato-?10 O 1,O 1?:O 2,O 2?:O 2?:O 4,O 4?:O 5:O 5,O 5?)dithallium(I)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compound, {(C2H10N2)[Tl2(C10H2O8)(H2O)2)]}n, was prepared using (enH2)2(btc)·2H2O and thallium(I) nitrate (en = ethyl­enediamine and btcH4 = benzene-1,2,4,5-tetra­carboxylic acid). The enH2 cation and btc ligand are each located on an inversion centre. The TlI atom is seven-coordinated by three btc ligands and two water mol­ecules in an irregular geometry due to the stereochemically active lone pair on the Tl centre. The water mol­ecule and btc ligand are bonded to the Tl atoms...

Rafizadeh, Masoud; Manteghi, Faranak

2008-01-01

160

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

2013-01-01

 
 
 
 
161

Degradation of toluene and m-xylene and transformation of o-xylene by denitrifying enrichment cultures.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Seven different sources of inocula that included sediments, contaminated soils, groundwater, process effluent, and sludge were used to establish enrichment cultures of denitrifying bacteria on benzene, toluene, and xylenes in the absence of molecular oxygen. All of the enrichment cultures demonstrated complete depletion of toluene and partial depletion of o-xylene within 3 months of incubation. The depletion of o-xylene was correlated to and dependent on the metabolism of toluene. No losses o...

Evans, P. J.; Mang, D. T.; Young, L. Y.

1991-01-01

162

Evidence for acetyl coenzyme A and cinnamoyl coenzyme A in the anaerobic toluene mineralization pathway in Azoarcus tolulyticus Tol-4  

Energy Technology Data Exchange (ETDEWEB)

Benzene, toluene, ethylbenzene, and xylenes (BTEX compounds) are primary contimantes of concern in aquifers and sediments where petroleum leakages and spills have occured. This paper describes anaerobic toluene metabolism by a new bacterium, which was isolated from petroleum contaminated aquifer sediment. Also provided is evidence for important modifications in the acetylCoA pathway of anaerobic toluene metabolism. 42 refs., 6 figs., 6 tabs.

Chee-Sanford, J.C.; Frost, J.W.; Fries, M.R.; Zhou, Jizhong [Michigan State Univ., East Lansing, MI (United States)] [and others

1996-03-01

163

Chronic neurobehavioural effects of toluene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neurobehavioural tests were undertaken by 30 female workers exposed to toluene and matched controls with low occupational exposure to toluene. The environmental air levels (TWA) of toluene was 88 ppm for the exposed workers and 13 ppm for the controls. The toluene in blood concentrations for the exposed workers was 1.25 mg/l and for the controls 0.16 mg/l. Statistically significant differences between workers exposed to toluene and controls in neurobehavioural tests measuring manual dexterity...

Foo, S. C.; Jeyaratnam, J.; Koh, D.

1990-01-01

164

Kinetics of toluene degradation by a nitrate-reducing bacterium isolated from a groundwater aquifer  

Energy Technology Data Exchange (ETDEWEB)

Groundwater from a xylene-contaminated aquifer was enriched in the laboratory in the presence of toluene, xylenes, ethylbenzene, and benzene. A pure culture that degrades toluene and m-xylene under nitrate-reducing conditions was isolated. Fatty acid analysis, 16S rRNA sequencing, and morphological traits indicate that the isolate was a strain of Azoarcus tolulyticus. The kinetics of toluene degradation under nitrate-reducing conditions by this isolate was determined. Nitrate reduction does not proceed beyond nitrite. Nitrate and toluene are substrate limiting at low concentrations, whereas toluene, nitrate, and nitrite are inhibitory at high concentrations. Several inhibition models were compared to experimental data to represent inhibition by these substrates. A kinetic model for toluene and nitrate degradation as well as for cell growth and nitrite production was developed and compared to experimental data. The results of this work may find important application in the remediation of groundwater aquifers contaminated with aromatic hydrocarbons.

Elmen, J.; Pan, W.; Leung, S.Y.; Magyarosy, A.; Keasling, J.D. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

1997-07-05

165

Kinetics of toluene degradation by a nitrate-reducing bacterium isolated from a groundwater aquifer.  

Science.gov (United States)

Groundwater from a xylene-contaminated acquifer was enriched in the laboratory in the presence of toluene, xylenes, ethylbenzene, and benzene. A pure culture that degrades toluene and m-xylene under nitrate-reducing conditions was isolated. Fatty acid analysis, 16S rRNA sequencing, and morphological traits indicate that the isolate was a strain of Azoarcus tolulyticus. The kinetics of toluene degradation under nitrate-reducing conditions by this isolate was determined. Nitrate reduction does not proceed beyond nitrite. Nitrate and toluene are substrate limiting at low concentrations, whereas toluene, nitrate, and nitrite are inhibitory at high concentrations. Several inhibition models were compared to experimental data to represent inhibition by these substrates. A kinetic model for toluene and nitrate degradation as well as for cell growth and nitrite production was developed and compared to experimental data. The results of this work may find important application in the remediation of groundwater aquifers contaminated with aromatic hydrocarbons. PMID:18636447

Elmén, J; Pan, W; Leung, S Y; Magyarosy, A; Keasling, J D

1997-07-01

166

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-(acetyloxyphenyl]-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

2013-07-01

167

Protein Engineering of Toluene-o-Xylene Monooxygenase from Pseudomonas stutzeri OX1 for Synthesizing 4-Methylresorcinol, Methylhydroquinone, and Pyrogallol  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Toluene-o-xylene monooxygenase (ToMO) from Pseudomonas stutzeri OX1 oxidizes toluene to 3- and 4-methylcatechol and oxidizes benzene to form phenol; in this study ToMO was found to also form catechol and 1,2,3-trihydroxybenzene (1,2,3-THB) from phenol. To synthesize novel dihydroxy and trihydroxy derivatives of benzene and toluene, DNA shuffling of the alpha-hydroxylase fragment of ToMO (TouA) and saturation mutagenesis of the TouA active site residues I100, Q141, T201, and F205 were used to ...

Vardar, Go?nu?l; Wood, Thomas K.

2004-01-01

168

CFD SIMULATIONS OF BENZENE –TOLUENE SYSTEM OVER SIEVE TRAY  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 conditio...

2012-01-01

169

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

2012-08-01

170

Toluene embryopathy: two new cases.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Toluene embryopathy is characterised by microcephaly, central nervous system dysfunction, attentional deficits and hyperactivity, developmental delay with greater language deficits, minor craniofacial and limb anomalies, and variable growth deficiency. Previously, three affected children, born to women who inhaled toluene regularly throughout pregnancy, have been reported. Two more cases are described emphasising the importance of toluene as a potential human teratogen.

Hersh, J. H.

1989-01-01

171

090317 Toluene supplementary note final  

Supplementary information for the derivation of SGV for toluene Better Regulation Science Programme Science report: SC050021 Technical Review Toluene - Supplementary information for the derivation of SGVs for toluene ii The Environment Agency is the leading public body protecting and improving the…

172

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 medium, accumulates m-cresol in the medium, indicating that m-cresol is an intermediate of toluene catabolism. Moreover, incubation of such cells in the presence of 18O2 followed by gas chromatography...

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

1994-01-01

173

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

2010-07-01

174

Overview of environmental and toxicological aspects of aromatic hydrocarbons. II. Toluene  

Energy Technology Data Exchange (ETDEWEB)

The salient aspects of the exposure to toluene were reviewed via an initial examination of the production, use, occurrence and disposition of toluene, as well as populations at potential risk. Special note should be taken as to the increasing use of toluene as a ''safe'' replacement for benzene in solvent applications and its increasing use in many consumer products. There is a broad potential for exposure by industrial workers and the general public (via vehicle exhausts and consumer products). The effects on humans and animals as well as the genetic effects of toluene were also reviewed following an initial consideration for its absorption and elimination. The narcotic and neurotoxic properties of toluene represent the main recognized health hazards to humans. 107 references.

Fishbein, L.

1985-04-01

175

Facts about Benzene  

Science.gov (United States)

... for All Disasters Illness Injury Food & Water Animals & Insects Returning Home After a Disaster Carbon Monoxide Environmental ... to benzene in the air. If the benzene release was outside, move away from the area where ...

176

Optical and dielectric functions of liquid methylated benzenes in the 2- to 10-eV spectral region  

Energy Technology Data Exchange (ETDEWEB)

The optical and dielectric functions have been determined in the 2 to 10-eV spectral region for four polycyclic hydrocarbons: benzene, toluene, xylene, and trimethylbenzene. The effect of substitution on the spectra of these liquid alkyl benzenes is investigated and comparisons are made to the appropriate gas-phase spectra.

Attrey, J.S.; Birkhoff, R.D.; Painter, L.R.

1982-12-01

177

Solubilities of some organic solutes in 1-ethyl-3-methylimidazolium acetate. Chromatographic measurements and predictions from COSMO-RS  

International Nuclear Information System (INIS)

Highlights: ? New solubility data are reported. ? Two experimental procedures for measuring solubilities are used. ? The experimental results from both procedures are compared. ? Experiments are compared with the theoretical calculations. - Abstract: Infinite-dilution activity coefficients and Henry’s constants for several organic solutes in 1-ethyl-3-methylimidazolium acetate [EMIM][Ac] were measured from T = 313 K to T = 413 K using two types of gas–liquid chromatography columns: packed columns and an open tubular wall-coated (OTWC) column. The organic solutes include n-hexane, 1-hexene, cyclohexane, heptane, benzene, toluene, ethyl acetate, tetrahydrofuran, 1,4-dioxane, acetonitrile, nitromethane, 1,2-methoxyethane, 1-propanol, 2-propanol, t-butanol and t-amyl alcohol. Results using packed columns are in good agreement with those using the OTWC column. However, there is a useful advantage associated with an OTWC column: for solutes such as alcohols, that have strong interactions with the stationary phase, measurements are faster due to their shorter retention time compared to those in packed columns.

2012-04-01

178

Biomonitoring of occupational toluene exposure  

Energy Technology Data Exchange (ETDEWEB)

Toluene exposure was studied in 20 workers employed in painting and hand-finishing in an art furniture factory. Toluene was determined in the environmental air of places of work and in the alveolar air and blood of the workers. Hippuric acid and cresols were also tested in the workers' urine. Blood and urine tests were carried out before the work shift on Monday and Friday morning and at the end of the work shift on Friday afternoon. The other tests were performed on Friday afternoon only. Alveolar toluene concentrations, which were significantly correlated with environmental toluene concentrations (r . 0.6230; P less than 0.01), corresponded to 19.4% of the toluene concentration in the atmosphere. Blood toluene was also found in painters on Monday morning and was significantly correlated with the other parameters. On Friday afternoon it was three times higher than the environmental toluene concentration. Urinary o-Cresol was highly correlated with toluene in the atmosphere, in blood and with hippuric acid in urine. On the basis of the slope of the regression line the ratio between urinary o-Cresol and blood toluene concentration was 0.99. At the end of the work shift urinary hippuric acid concentration was highly correlated with o-Cresoluria and with toluene in blood and in the atmosphere.

Apostoli, P.; Brugnone, F.; Perbellini, L.; Cocheo, V.; Bellomo, M.L.; Silvestri, R.

1982-01-01

179

Possible genotoxicity in low level benzene exposure.  

Science.gov (United States)

Structural chromosome aberrations and sister chromatid exchanges (SCEs) in peripheral blood were studied in female workers employed in the shoe-making industry in two periods: 1987 (group I; N = 38) and 1992 (group II; N = 45). Only 11 of the workers were present in both groups and their results are presented both together and separately. Occupational exposure to benzene and toluene was confirmed through their determination in the working area, blood, and phenol in pre- and post-shift urine. The results were compared with those from the control group (N = 35). Benzene in the working atmosphere was significantly higher in 1987 compared to 1992, but was always lower than the current Croatian permissible concentration of 50 mg m-3 (in the near future this value will be changed to 15 mg m-3). A statistically significant difference was also found in biological markers of benzene exposure between the two periods of the investigation. Increased absorption in the first period occurred because of intensified production in 1987, and this decreased significantly in 1992 because of the war in Croatia. The cytogenetic study showed a significant increase in dicentric chromosomes in exposed groups I and II when compared to the control group. Statistically significant higher SCE frequencies were found in group I compared to the control group and also compared to group II. Between exposed group II and the controls no statistically significant difference in SCEs was found. Comparing the same 11 workers present in both periods the results showed no difference in chromosome aberrations between the two periods of examination. SCE frequencies were significantly higher in 1987 when greater benzene absorption occurred, confirmed by biomarkers of benzene exposure. The presented results indicate that genotoxicity may occur in workers exposed to low levels of benzene in the shoe industry. PMID:7747744

Karaci?, V; Skender, L; Bosner-Cucanci?, B; Bogadi-Sare, A

1995-03-01

180

Benzene: questions and answers  

International Nuclear Information System (INIS)

This information booklet is intended to inform residents near natural gas dehydration facilities about benzene and its levels in the atmosphere. It was issued following the federal government's decision to place benzene on its Priority Substances List and to require industry to establish means for reducing benzene emissions from natural gas dehydrators and to inform residents about benzene emissions from glycol dehydration facilities. Accordingly, the booklet explains what benzene is (a colourless flammable liquid component of hydrocarbons) how it gets into the air (during gasoline refining, vehicle refueling and the production of steel and petrochemicals), the associated health hazards (a recognized carcinogen, causing an increased incidence of leukemia in concentrations of 100 parts per million), defines a glycol dehydrator (a facility built at or near some natural gas fields for the removal of water from the natural gas to prevent corrosion and freezing of pipelines), and enumerates the steps that are being taken to reduce benzene levels in the air (benzene levels in gasoline have been reduced, along with benzene emissions from petrochemical plants, refineries, steel plants and glycol dehydrators by 54 per cent to date; this will rise to 90 per cent by 2005). In addition to these actions, industry plans call for all existing glycol dehydrators within 750 metres of any permanent residence to be limited to benzene emissions of no more than three tonnes per year before 2001; new glycol dehydrators after that date will be expected to have benzene emissions reduced to the lowest level that can be practically achieved

1999-01-01

 
 
 
 
181

Tetraethylammonium toluene-4-sulfonate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There are two tetraethylammonium cations and two toluene-4-sulfate anions in the asymmetric unit of the title salt, C8H20N+·C7H7O3S?. One of the anions is disordered over two positions, with refined occupancies of 0.447?(3) and 0.553?(3). In the crystal, the cations and anions are linked by C—H...O hydrogen bonds, forming ribbons along [10-1]. The ribbons are linked via C—H...O hydrogen bonds, forming a two-dimensional network lying parallel to (10-1).

Diana Malgorzata Brus; Justyna Czyrko; Krzysztof Brzezinski

2013-01-01

182

Demand boom boosts ethyl, butyl acetate  

International Nuclear Information System (INIS)

US ethyl and butyl acetate markets are being described as 'extremely tight.' One major domestic producer is 'in a sold-out position' and has 'gone on sales control' with respect to these two products. Producers say that sales of both ethyl and butyl acetate have increased during the past year, and industry observers say they expect to see an April 1 price initiative of 2 cts to 3 cts/lb, and possibly a second increase in October. While one producer suggests that this market strength could be 'a sign that the coatings industry is turning around,' most agree that reformulation is the principal driver of growth. Ethyl acetate is said to be replacing methyl ethyl ketone in many formulations, while butyl acetate and butyl acetate blends are substituting for methyl isobutyl ketone. In addition, both ethyl and butyl acetate work as substitutes for xylene and toluene in certain applications. In an effort to conform to the requirements of the Clean Air Act of 1990 and to cooperate with the Environmental Protection Agency's 33/50 voluntary emissions reduction program, coatings manufacturers are moving as quickly as possible to eliminate solvents from their products. And although solvents as a whole will eventually see a dramatic decline in consumption, the temporary beneficiaries of reformulation will be certain of the oxygenated solvents, says Jeff Back, business manager at Kline ampersand Co

1993-02-24

183

Thermodynamics of biofuels: Excess enthalpies for binary mixtures involving ethyl 1,1-dimethylethyl ether and hydrocarbons at different temperatures using a new flow calorimeter  

International Nuclear Information System (INIS)

Excess molar enthalpies for the binary systems: (ethyl 1,1-dimethylethyl ether + heptane); (ethyl 1,1-dimethylethyl ether + cyclohexane); (ethyl 1,1-dimethylethyl ether + toluene); (cyclohexane + toluene), and (toluene + heptane) have been measured at T = (298.15 and 313.15) K using a new isothermal flow calorimeter developed in the laboratory. The technique was previously checked by measuring test systems. The experimental results have been correlated with the Redlich-Kister polynomial equation. The mixing effects observed and the influence of the temperature are discussed.

2009-06-01

184

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

185

090317 Toluene SGV publication final  

…(personal communication, 2009), average background concentrations of toluene in glacial drift deposits on a large housing estate in an urban area of the West Midlands were below the detection limit of 1 g kg-1 . ECB (2003) reported average toluene concentrations in unspecified soils in the Netherlands…

186

090317 Toluene SGV publication final  

…Criteria Values for toluene are summarised in Table 1. The recommended inhalation tolerable daily intake (TDI) is based on CNS effects seen in workers exposed to toluene. Toxicity data from repeated oral exposure are not available for humans. The recommended oral TDI in Table 1 is based on increased liver…

187

090317 Toluene SGV publication final  

…used in industry as an intermediate in the production of other substances (ECB, 2003). A major use of toluene is as a petrol additive to improve octane rating (ATSDR, 2000). The average concentration of toluene in UK fuels is 5 to 11 per cent (CONCAWE, 1997; UKPIA, 2005). The annual petrol consumption…

188

090317 Toluene supplementary note final  

…Better Regulation Science Programme Science report: SC050021 Technical Review Toluene - Supplementary information for the derivation of SGVs for toluene ii The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It's our job to make sure that air,…

189

1-Ethyl-3-(2,4,6-trimethylphenylimidazolium 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-trimethylphenylimidazolium tetrafluoroborate with sodium tetrafluoroborate. The imidazole ring makes a dihedral angle of 78.92?(13° with the benzene ring.

Jin-Tao Guan

2010-08-01

190

Thermodynamic parameters of conformational equilibrium in 1,2-dichloroethane: influence of medium, benzene and compensation effects  

Science.gov (United States)

The conformational equilibrium of 1,2-dichloroethane (DCE) in 19 different media (vapour phase, liquid, solutions in n-hexane, n-heptane, carbon tetrachloride, benzene, toluene, ethyl benzene (EB), carbon disulphide, diethyl ether, bromoform, chloroform, dichloromethane, pyridine, acetone, methanol- d3, acetonitrile, glassy polystyrene (PS) matrix and 1:1 mixture of PS and EB) has been studied by IR absorption spectra. The enthalpy differences ( ?H0) between trans (t) and gauche (g) conformers were determined from the dependencies of 1n( It/ Ig) upon T-1, where I1 and Ig are the integrated intensities of the bands belonging to trans and gauche conformers, respectively. The values of RT ln( It/ Ig) and ( R ln( It/ Ig) + ?H0/ T) obtained at 296 K were used as measures of the free enthalpy ( ?G0) and entropy ( ?SD) differences of the conformers respectively, when considering their changes with solvent. Good correlations between ?G0, ?H0 and the function of the dielectric permittivity of the medium ( 0.5 - (? - 1)/(2? + 1)) 1/2 were observed for all solvents except methanol- d3 (effect of self-association) and the aromatic solvents (benzene effect). Notwithstanding the similar structures and dielectric permittivities of EB and PS, the former medium behaves as a significantly more polar solvent. The analysis of the ?H0 values obtained for DCE in PS and EB enabled confirmation of Eliel and Hofer's concept of the origin of the benzene effect; the effect is assigned to the relatively high anisotropy of the polarizability tensor of aromatic compounds. As a consequence, the electrostatic and dispersion interactions of a solute dipole with a neighbouring aromatic ring is crucial to their mutual orientation. Significantly non-linear (close to quadratic) dependencies ln( It/ Ig) = f( T-1) were observed for DCE in toluene and EB in the range 180-370 K: the ?H0 value increased from -170 cal mol -1 at 358 K to 820 cal mol -1 at 190 K for the toluene solution. These results are considered within the framework of the manifestations of the benzene effect. Significant changes in ?S0 with the media have been found; they cover more than 2.0 cal mol -1 K -1 when going from the vapour phase to polar solvents. Satisfactory correlation between ?H0 and ?S0 (compensation effect) has been observed, the points corresponding to all the media, including methanol- d4 and the aromatic solvents, being scattered along a straight line. The tangent of the slope ( ??S0/ ??HD) = (1.4 ± 0.4) × 10 -3 K -1 is close to those determined earlier for 1,2-bromofluoroethane, trans-1,2-dichlorocyclohexane and o-iodophenol.

Stolov, A. A.; Remizov, A. B.

1995-10-01

191

090323 Benzene SGV final  

…to be degraded last (ATSDR, 2007). Exposure assessment Occurrence in soil Most soils will contain very little, if any, benzene as a result of natural processes. Benzene is released to the soil environment through industrial discharges, waste disposal, fuel leaks or spillages (IPCS, 1993; ATSDR, 2007)…

192

090323 Benzene SGV final  

…degreasing agents; in the production of artificial leather and rubber goods and in the shoe industry. Benzene is also added to petrol to improve the octane rating (ATSDR, 2007). The European petrol quality requirements limit benzene in petrol to a maximum of one percent by volume (ECB, 2007). Annual consumption…

193

090323 Benzene SGV final  

…benzene SGV SCHO0309BPQI-E-P 2 Uses as a solvent include/included: in the manufacture of products such as solvents, industrial paints, rubber cements, adhesives, paint removers and degreasing agents; in the production of artificial leather and rubber goods and in the shoe industry. Benzene is also added to…

194

Novel Toluene Elimination System in a Toluene-Tolerant Microorganism  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In studies of Pseudomonas putida IH-2000, a toluene-tolerant microorganism, membrane vesicles (MVs) were found to be released from the outer membrane when toluene was added to the culture. These MVs were found to be composed of phospholipids, lipopolysaccharides (LPS), and very low amounts of outer membrane proteins. The MVs also contained a higher concentration of toluene molecules (0.172 ± 0.012 mol/mol of lipid) than that found in the cell membrane. In contrast to the wild-type strain, th...

Kobayashi, Hideki; Uematsu, Katsuyuki; Hirayama, Hisako; Horikoshi, Koki

2000-01-01

195

Soot formation in shock-tube pyrolysis of toluene, toluene-methanol, toluene-ethanol, and toluene-oxygen mixtures  

Energy Technology Data Exchange (ETDEWEB)

Soot formation during the pyrolysis of argon diluted mixtures of toluene and binary mixtures of toluene-methanol and toluene-ethanol, and during the oxidation of toluene has been studied in a reflected shock tube. Soot induction times and rates of soot formation were measured at 632.8 and 1,152.0 nm by a laser beam attenuation method and these showed an Arrhenius dependence on shock temperature. Soot yields and soot amounts were also measured. The soot yield and amount were found to decrease with the addition of methanol and ethanol to toluene, with more pronounced effects for the methanol addition. The addition of oxygen to toluene strongly suppressed soot with a shift of the soot yield to lower temperatures. This laser effect was not found during alcohol addition to the toluene and therefore an alternative route to the soot formation at lower temperatures is suggested. A kinetic model was used to interpret the experimental trends and reasonably reproduced the experimental observations. However, the lack of good quantitative agreement emphasized the urgent need in establishing reliable kinetic data and reaction pathways on the oxidation of the benzyl radical and PAH species.

Alexiou, A.; Williams, A. [Leeds Univ. (United Kingdom). Dept. of Fuel and Energy

1996-01-01

196

Calorimetric study of methyl and ethyl 2-thiophenecarboxylates and ethyl 2- and 3-thiopheneacetates  

International Nuclear Information System (INIS)

The standard (p0=0.1MPa) molar enthalpies of formation, in the condensed phase, of the liquids methyl 2-thiophenecarboxylate, ethyl 2-thiophenecarboxylate, ethyl 2-thiopheneacetate, and ethyl 3-thiopheneacetate, at T = 298.15 K, were derived from the standard massic energies of combustion, in oxygen, to yield CO2 (g) and H2SO4 . 115H2O (aq), measured by rotating bomb combustion calorimetry. For these four compounds, the standard molar enthalpies of vaporization, ?lgHm0, at T = 298.15 K, were obtained by high temperature Calvet microcalorimetry. The standard (p0=0.1MPa) molar enthalpies of formation, in the gaseous phase, were derived from the experimental results and they are interpreted in terms of enthalpic increments of the introduction of a methylene group to the substituent chain. Moreover, the results are compared with the analogue benzene derivative.

2009-08-01

197

Benzene from Traffic : Fuel Content and Ambient Air Concentrations  

DEFF Research Database (Denmark)

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

Palmgren, F.; Berkowicz, R.

2000-01-01

198

090317 Toluene SGV publication final  

…into soil, toluene will tend to sink through the unsaturated zone until it reaches the saturated zone (Environment Agency, 2003). It is a light non-aqueous phase liquid (LNAPL) and will tend to collect at the

199

090317 Toluene SGV publication final  

…reported average toluene concentrations in unspecified soils in the Netherlands of 0.001 mg kg-1 , while seven samples from uncontaminated sites in Florida, USA, reported results below the detection limit of

200

Effects of ethanol on blood toluene concentrations  

Energy Technology Data Exchange (ETDEWEB)

The metabolism of toluene was found to be inhibited by a large dose of alcohol in seven volunteers exposed to 80 ppm of toluene under experimental conditions. When alcohol was taken during exposure, blood toluene concentrations were 42.5% greater on average than during exposure with no alcohol. This is probably due to competition for alcohol dehydrogenase which is required for the breakdown of both ethanol and toluene. In men exposed to toluene at work, it was found that blood toluene concentrations were lowest in those who drank regularly. These results suggest that continued alcohol intake increases the metabolism of toluene, presumably by inducing the microsomal oxidising enzyme system in the liver.

Waldron, H.A.; Cherry, N.; Johnston, J.D.

1983-04-01

 
 
 
 
201

Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol relate...

Inoue, O.; Seiji, K.; Nakatsuka, H.; Watanabe, T.; Yin, S.; Li, G. L.; Cai, S. X.; Jin, C.; Ikeda, M.

1989-01-01

202

Toxicological profile for toluene. Update. Final report  

Energy Technology Data Exchange (ETDEWEB)

This Statement was prepared to give you information about toluene and to emphasize the human health effects that may result from exposure to it. Toluene has been found in at least 851 of the sites on the NPL. However, the number of NPL sites evaluated for toluene is not known. This information is important because exposure to toluene may cause harmful health effects and because these sites are potential or actual sources of human exposure to toluene.

Dorsey, A.S.; Donohue, J.M.

1994-05-01

203

Measurements of photo-oxidation products from the reaction of a series of alkyl-benzenes with hydroxyl radicals during EXACT using comprehensive gas chromatography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Photo-oxidation products from the reaction of a series of alkyl-benzenes, (benzene, toluene, p-xylene and 1,3,5-trimethyl-benzene) with hydroxyl radicals in the presence of NOx have been investigated using comprehensive gas chromatography (GCxGC). A GCxGC system has been developed which utilises valve modulation and independent separations as a function of both volatility and polarity. A number of carbonyl-type compounds were identified during a series of reactions carr...

Hamilton, J. F.; Lewis, A. C.; Bloss, C.; Wagner, V.; Henderson, A. P.; Golding, B. T.; Wirtz, K.; Martin-reviejo, M.; Pilling, M. J.

2003-01-01

204

Leukemia and Benzene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the numbers of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow...

Robert Snyder

2012-01-01

205

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

Science.gov (United States)

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. PMID:24052143

Olszowski, Tomasz; K?os, Andrzej

2013-11-01

206

Measuring the static dielectric constants of pure carbon dioxide and carbon dioxide mixed with ethanol and toluene at elevated pressures  

Energy Technology Data Exchange (ETDEWEB)

Static dielectric constants (relative permittivities) of binary carbon dioxide/ethanol mixtures and carbon dioxide/toluene mixtures of various compositions at 10 MPa and 313 K, which were experimentally determined, are presented. In addition, the dielectric constant of pure carbon dioxide was measured at temperatures of 293, 313 and 336 K in the pressure range of up to 30 MPa. The measurements were conducted with a new type of sensor design. The dielectric constant of pure carbon dioxide shows a pronounced dependence on pressure close to the critical pressure. There is a nearly linear relationship between density and the dielectric constant. The dielectrical behavior of the mixtures of supercritical carbon dioxide with ethanol and toluene is qualitatively very similar to that of liquid benzene/ethanol and benzene/toluene mixtures at normal pressure. (orig.)

Wesch, A. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Technische Chemie; Dahmen, N. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Technische Chemie; Ebert, K.H. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Technische Chemie

1996-08-01

207

Jailbreaking benzene dimers.  

Science.gov (United States)

We suggest four new benzene dimers, (C(6)H(6))(2), all featuring one or more cyclohexadiene rings trans-fused to 4- or 6-membered rings. These hypothetical dimers are 50-99 kcal/mol less stable than two benzenes, but have computed activation energies to fragmentation ?27 kcal/mol. A thorough search of potential escape routes was undertaken, through cyclobutane ring cleavage to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of the 6-membered rings, and Diels-Alder dimerizations. Some channels for reaction emerge, but there is a reasonable chance that some of these new benzene dimers can be made. PMID:22536749

Rogachev, Andrey Yu; Wen, Xiao-Dong; Hoffmann, Roald

2012-05-16

208

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

209

Sensitive detection of a novel class of toluene-degrading denitrifiers, Azoarcus tolulyticus, with small-subunit rRNA primers and probes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Azoarcus tolulyticus is a new class of widely distributed toluene-degrading denitrifiers of potential importance in remediating benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated environments. To detect these organisms in the environment, 16S rRNA gene-based phylogenetic probes were developed. Two sets of specific PCR amplification primers and two oligonucleotide hybridization probes were designed and tested against both closely and distantly related environmental isolates. All of...

1997-01-01

210

Assessment of the Amur River ecosystem pollution with benzene and its derivatives caused by an accident at the chemical plant in Jilin City, China.  

Science.gov (United States)

Assessment of concentrations of benzene and its derivatives in the Amur water and fish caught in summer and autumn 2006 was carried out after Jilin chemical plant accident (winter 2005) in the People’s Republic of China. Fish sampling of Leiocassis ussuriensis conducted in the Amur River near Khabarovsk identified benzene, toluene, ethylbenzene, isopropylbenzene, xylene reaching to 16, 98.7, 55, 54, and 206 ?g kg?1, respectively. For Hypophthalmichtys molitrix Valenciennes sampled in the lower reaches of the Amur benzene, toluene, ethylbenzene, xylene were found in amounts to 9, 15.4, 16 ?g kg?1, and, benzene and xylene reaching 6 and 16 ?g kg?1 were found in Huso dauricus and benzene and xylene of 2–6 and 13–16 ?g kg?1, respectively, in Acipenser schrenckii. The above toxicants were not detected in the Amur water near the river mouth in autumn 2006. PMID:19572090

Levshina, S I; Efimov, N N; Bazarkin, V N

2009-12-01

211

Anaerobic degradation of alkylated benzenes in denitrifying laboratory aquifer columns  

International Nuclear Information System (INIS)

Toluene and m-xylene were rapidly mineralized in an anaerobic laboratory aquifer column operated under continuous-flow conditions with nitrate as an electron acceptor. The oxidation of toluene and m-xylene was coupled with the reduction of nitrate, and mineralization was confirmed by trapping 14CO2 evolved from 14C-ring-labeled substrates. Substrate degradation also took place when nitrous oxide replaced nitrate as an electron acceptor, but decomposition was inhibited in the presence of molecular oxygen or after the substitution of nitrate by nitrite. The m-xylene-adapted microorganisms in the aquifer column degraded toluene, benzaldehyde, benzoate, m-toluylaldehyde, m-toluate, m-cresol, p-cresol, and p-hydroxybenzoate but were unable to metabolize benzene, naphthalene, methylcyclohexane, and 1,3-dimethylcyclohexane. Isotope-dilution experiments suggested benzoate as an intermediate formed during anaerobic toluene metabolism. The finding that the highly water-soluble nitrous oxide served as electron acceptor for the anaerobic mineralization of some aromatic hydrocarbons may offer attractive options for the in situ restoration of polluted aquifers

1988-01-01

212

A detailed kinetic modeling study of toluene oxidation in a premixed laminar flame  

Energy Technology Data Exchange (ETDEWEB)

An improved chemical kinetic model for the toluene oxidation based on experimental data obtained in a premixed laminar low-pressure flame with vacuum ultraviolet (VUV) photoionization and molecular beam mass spectrometry (MBMS) techniques has been proposed. The present mechanism consists of 273 species up to chrysene and 1740 reactions. The rate constants of reactions of toluene, decomposition, reaction with oxygen, ipso-additions and metatheses with abstraction of phenylic H-atom are updated; new pathways of C{sub 4} + C{sub 2} species giving benzene and fulvene are added. Based on the experimental observations, combustion intermediates such as fulvenallene, naphtol, methylnaphthalene, acenaphthylene, 2-ethynylnaphthalene, phenanthrene, anthracene, 1-methylphenanthrene, pyrene and chrysene are involved in the present mechanism. The final toluene model leads to an overall satisfactory agreement between the experimentally observed and predicted mole fraction profiles for the major products and most combustion intermediates. The toluene depletion is governed by metathese giving benzyl radicals, ipso-addition forming benzene and metatheses leading to C{sub 6}H{sub 4}CH{sub 3} radicals. A sensitivity analysis indicates that the unimolecular decomposition via the cleavage of a C-H bond has a strong inhibiting effect, while decomposition via C-C bond breaking, ipso-addition of H-atom to toluene, decomposition of benzyl radicals and reactions related to C{sub 6}H{sub 4}CH{sub 3} radicals have promoting effect for the consumption of toluene. Moreover, flow rate analysis is performed to illustrate the formation pathways of mono- and polycyclic aromatics.

Tian, Z; Pitz, W J; Fournet, R; Glaude, P; Battin-Leclerc, F

2009-12-18

213

090317 Toluene SGV publication final  

…bw = bodyweight MDI = mean daily intake TDI = tolerable daily intake 3 urban or rural soils. According to Wolverhampton City Council (personal communication, 2009), average background concentrations of toluene in glacial drift deposits on a large housing estate in an urban area of the West Midlands were…

214

090317 Toluene SGV publication final  

…nervous system (CNS) is the main human health concern following medium- to long-term inhalation exposure. Although there is a lack of human studies of oral toxicity, nervous system toxicity has been observed in animal studies following ingestion. Health Criteria Values for toluene are summarised in Table…

215

090317 Toluene supplementary note final  

…stems and leaves (Collins et al., 2002). Upon entering the leaves, toluene may be lost through transpiration or metabolised (Burken and Schnoor, 1998). Any resulting metabolites can either be transpired, or retained in the leaves as bound residues (Collins et al., 2002), or incorporated into cell structures…

216

090317 Toluene supplementary note final  

…various extents - depending on plant species - by loss through volatilisation and transpiration. Gaseous pollutants primarily enter leaves via their stomata, but can also be absorbed through the epidermis of aboveground parts. Uptake of gaseous toluene by leaves varies between plant species, depending on…

217

090317 Toluene supplementary note final  

…means that roots are an important organ for metabolism of organic compounds (Collins et al., 2002). Resulting metabolites may be retained in the roots or transported around the plant. These metabolites may be more or less toxic to humans than the original organic chemical. As toluene is only moderately…

218

090317 Toluene SGV publication final  

…background to the CLEA model (Environment Agency, 2009b) and Human health toxicological assessment of contaminants in soil (Environment Agency, 2009c), and Contaminants in soil: updated collation of toxicological data and intake values for humans. Toluene (Environment Agency, 2009d). Supplementary information…

219

090317 Toluene SGV publication final  

…2003). Toluene is used as an intermediate or as a solvent in the manufacture of numerous products including household aerosols, paint, varnishes, adhesives, glue, explosives, dyes, detergents, pesticides, wood preservatives, pharmaceuticals, nail polish, cosmetics, stain removers, fabric dyes and in some…

220

090317 Toluene supplementary note final  

…Dissemination Status: Publicly available / released to all regions Keywords: Toluene, plant uptake, vegetable, fruit, soil-to-plant concentration factor Environment Agency's Project Manager: Jo Jeffries Science Department Science Project Number: SC050021 Product Code: SCHO0309BPQD-E-P This report is…

 
 
 
 
221

090317 Toluene supplementary note final  

…were carried out in October 2008 to identify toluene soil-to-plant concentration factors for the produce categories used within the CLEA model. Section 2.3 provides a review of the available literature. These databases cover the period 1992 to present. The databases were searched for publications from…

222

090317 Toluene SGV publication final  

…Toluene is used as an intermediate or as a solvent in the manufacture of numerous products including household aerosols, paint, varnishes, adhesives, glue, explosives, dyes, detergents, pesticides, wood preservatives, pharmaceuticals, nail polish, cosmetics, stain removers, fabric dyes and in some printing…

223

090323 Benzene SGV final  

…intermediate in the production of other chemicals: ethylbenzene (used to make styrene), cumene (used to make phenol and acetone), cyclohexane (used to make nylon), nitrobenzene, alkylbenzene, maleic acid anhydride and chlorinated benzenes (IPCS, 1993; ATSDR, 2007; ECB, 2007). The estimated annual production of…

224

Economical benzene emission reduction  

International Nuclear Information System (INIS)

Benzene has been classified as a toxic compound under the Canadian Environmental Protection Act. This has prompted the Alberta Energy and Utilities Board (AEUB) to introduce specific reporting and monitoring guidelines for the oil and gas industry regarding excessive benzene emissions. Glycol dehydration units have been determined to be the major single source of benzene emissions causing air and soil pollution. DualTank Corp. has designed a condensation and storage tank unit to enhance emission reduction, odour elimination and liquid recovery from dehydration units. Their newly designed combined tank unit consists of a large, uninsulated surface area for cooling, and an excessive internal volume for increased retention time. The first prototype was installed in December 1998 at an Enerplus Resources Site. The system provides excellent benzene emission reduction and the elimination of odours and visual plumes. Effective January 1, 1999, the petroleum and natural gas industry must either clean up excessive emissions voluntarily or face government imposed regulations, facility shutdowns and/or fines. 1 fig

1999-05-01

225

Economical benzene emission reduction  

Energy Technology Data Exchange (ETDEWEB)

Benzene has been classified as a toxic compound under the Canadian Environmental Protection Act. This has prompted the Alberta Energy and Utilities Board (AEUB) to introduce specific reporting and monitoring guidelines for the oil and gas industry regarding excessive benzene emissions. Glycol dehydration units have been determined to be the major single source of benzene emissions causing air and soil pollution. DualTank Corp. has designed a condensation and storage tank unit to enhance emission reduction, odour elimination and liquid recovery from dehydration units. Their newly designed combined tank unit consists of a large, uninsulated surface area for cooling, and an excessive internal volume for increased retention time. The first prototype was installed in December 1998 at an Enerplus Resources Site. The system provides excellent benzene emission reduction and the elimination of odours and visual plumes. Effective January 1, 1999, the petroleum and natural gas industry must either clean up excessive emissions voluntarily or face government imposed regulations, facility shutdowns and/or fines. 1 fig.

Schuetz, R. [DualTank Corp., Calgary, AB (Canada)

1999-05-01

226

Biodegradation of Benzene.  

Science.gov (United States)

Two species of bacteria capable of degrading the aromatic hydrocarbon benzene in vivo have been isolated from soil samples that were obtained from areas which had been drenched with kerosene (JP-4), gasoline, and diesel fuel for several years. It was reas...

B. M. Agerton J. C. Cornette

1973-01-01

227

090323 Benzene SGV final  

…produced is used as a chemical intermediate in the production of other chemicals: ethylbenzene (used to make styrene), cumene (used to make phenol and acetone), cyclohexane (used to make nylon), nitrobenzene, alkylbenzene, maleic acid anhydride and chlorinated benzenes (IPCS, 1993; ATSDR, 2007; ECB, 2007…

228

Benzene hematotoxicity and leukemogenesis  

Energy Technology Data Exchange (ETDEWEB)

Benzene is ubiquitous and accepted as a human carcinogen by regulatory agencies. Proposed regulations assume without proof that the carcinogenic response to benzene exposure is one hit implying a linear with no threshold. There is no solid experimental proof for this concept. This research involves exposure of CBA/Ca male mice to benzene vapor in varying concentrations. Exposure to 300 ppm 6 hrs/day, 5 days/week, for 16 weeks is highly leukemogenic. Exposure for the same time to 100 ppm is also leukemogenic. Concentrations from 25 ppm to 400 ppm 6 hrs/day, 5 days/week, for 10 exposures produce an increasing lymphopenia. Exposure to 100 ppm for the same exposure time produces anemia, decrease in stem cell content of marrow, and marrow cellularity. Further dose-effect studies are required to test the one hit hypothesis and to determine whether the same integral dose of benzene administered over variable exposure has the same or different biological responses. It is of concern that biologic effects are observed at 25 ppm only 2.5 times the present permissible time-weighted average exposure during a working day and research by others has demonstrated an effect (noncarcinogenic) at 10 ppm. 18 references, 1 figure.

Cronkite, E.P.

1986-01-01

229

090323 Benzene SGV final  

…also an important industrial chemical and is produced commercially by recovery from both petroleum and coal sources and from condensate from natural gas production (ATSDR, 2007; ECB, 2007). The majority of benzene is recovered from the petrochemical and petroleum refining industries where sources include…

230

27 CFR 21.132 - Toluene.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Toluene. 21.132 Section 21.132 Alcohol...Specifications for Denaturants § 21.132 Toluene. (a) Distillation range. ...Standard No. D 362-75 for industrial grade toluene; for incorporation by reference,...

2010-04-01

231

Neurobehavioral Effects of Toluene: A Review.  

Science.gov (United States)

Toluene appears to produce reversible effects upon liver, renal and nervous systems. Its usual route of intake is via respiration. The nervous system appears to be the most sensitive to the effects of toluene. Although there are few studies of toluene's n...

V. A. Benignus

1981-01-01

232

Hematotoxicity and carcinogenicity of benzene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

1989-01-01

233

090320 benzene supplementary note final  

Supplementary information for the derivation of SGV for benzene Better Regulation Science Programme Science report: SC050021 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the…

234

Pallidol hexa-acetate ethyl acetate monosolvate  

Science.gov (United States)

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.

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

2013-01-01

235

Biodegradation of benzene and a BTX mixture using immobilized activated sludge  

Energy Technology Data Exchange (ETDEWEB)

Aerobic biodegradation of benzene was studied using activated sludge immobilized in calcium alginate (immobilization by entrapment), and also attached to a silica based catalyst support (immobilization by attachment). Hydrogen peroxide was used as a source of dissolved oxygen to eliminate physical removal of benzene due to aeration. Abiotic losses of benzene were accounted for. A recirculation reactor, run in both batch and continuous feed mode, was used to determine the kinetic parameters. The system response was examined by following changes in benzene concentration, flow rate, and biomass loading. The system was modeled mathematically and the kinetic parameters were determined. Biological removal of a mixture of benzene, toluene and o, m and p-xylene (BTX) was also studied. In a typical batch experiment starting with 100 ppm benzene, the substrate utilization rate (k{sub M}), when expressed per unit weight of dry catalyst, had a value of 0.4453 ppm/h/g dry beads for the alginate system, and 0.067 ppm/h/g dry beads for the celite catalyst carrier. Activated sludge was characterized for biodegradation of benzene. Isolations were done for unacclimated, acclimated and end run samples. About 67% of the isolates could be assigned to a genus. These were Bacillus, Microbacterium, Plesiomonas, Kurthia, Klebsiella, Lactobacillus, and Pseudomonas. From among the fifteen isolates found in the end run group, an isolate identified as Pseudomonas was established as a primary degrader of benzene.

Lodaya, M.P.

1989-01-01

236

Toluene stability Space Station Rankine power system  

Science.gov (United States)

A dynamic test loop is designed to evaluate the thermal stability of an organic Rankine cycle working fluid, toluene, for potential application to the Space Station power conversion unit. Samples of the noncondensible gases and the liquid toluene were taken periodically during the 3410 hour test at 750 F peak temperature. The results obtained from the toluene stability loop verify that toluene degradation will not lead to a loss of performance over the 30-year Space Station mission life requirement. The identity of the degradation products and the low rates of formation were as expected from toluene capsule test data.

Havens, V. N.; Ragaller, D. R.; Sibert, L.; Miller, D.

1987-01-01

237

Thermodynamics of mixtures involving some (benzene derivatives+benzonitrile)  

International Nuclear Information System (INIS)

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 VE and Cp,mE are obtained. The magnitude of these experimental quantities together with HE literature data is discussed in terms of the nature and type of intermolecular interactions in binary mixtures

2007-04-01

238

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Zeng, Wu-lan

2008-01-01

239

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

240

Acute neurobehavioural effects of toluene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An acute inhalation chamber study of 42 college students was performed to investigate the relation between exposure to 0, 75, and 150 ppm of toluene and changes in central nervous system function and symptoms. Paid subjects were exposed for seven hours over three days. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory); perception (pattern recognition); psychomotor skill (simple reaction time, continuous performance, digit symbol, hand-eye coordination, finger...

Echeverria, D.; Fine, L.; Langolf, G.; Schork, A.; Sampaio, C.

1989-01-01

 
 
 
 
241

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)

1962-03-01

242

Altering Toluene 4-Monooxygenase by Active-Site Engineering for the Synthesis of 3-Methoxycatechol, Methoxyhydroquinone, and Methylhydroquinone  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Wild-type toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 oxidizes toluene to p-cresol (96%) and oxidizes benzene sequentially to phenol, to catechol, and to 1,2,3-trihydroxybenzene. In this study T4MO was found to oxidize o-cresol to 3-methylcatechol (91%) and methylhydroquinone (9%), to oxidize m-cresol and p-cresol to 4-methylcatechol (100%), and to oxidize o-methoxyphenol to 4-methoxyresorcinol (87%), 3-methoxycatechol (11%), and methoxyhydroquinone (2%). Apparent Vmax values ...

2004-01-01

243

Cross-regulation of toluene monooxygenases by the transcriptional activators TbmR and TbuT.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The toluene-3-monooxygenase from Burkholderia pickettii PKO1 and the toluene/benzene-2-monooxygenase from Burkholderia (Pseudomonas) sp. strain JS150 are distinct enzymes which differ not only in catalytic specificity and substrate range but also in the arrangement and sequence of the genes within the operons that encode the enzymes, tbuA1UBVA2C and tbmABCDEF, respectively. In the present study, we examined the transcriptional activation of the PtbuA1 and PtbmA promoters by their cognate regu...

Leahy, J. G.; Johnson, G. R.; Olsen, R. H.

1997-01-01

244

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 be...

2006-01-01

245

Toluene depresses plasma corticosterone in pregnant rats  

DEFF Research Database (Denmark)

Combined exposure to stressors and chemicals may result in synergistic effects. The effects of prenatal exposure to the organic solvent toluene resemble those observed in offspring of gestationally stressed dams, a possible common mechanism being transfer of stress-/toluene-induced increments of corticosteroids from the maternal to the foetal compartment. Pregnant rats were subjected to either 1500 ppm toluene 6 hr/day and/or a schedule of "Chronic mild stress" during the last two weeks of gestation. Exposure to toluene was associated with reduced birth weight and lower maternal weight gain, the latter being enhanced by maternal stress. A depressant effect of toluene on maternal corticosterone was observed, hence the study does not provide immediate evidence that transfer of elevated levels of corticosterone from the maternal to the foetal compartment mediates the effects of prenatal exposure to toluene.

Hougaard, Karin S; Hansen, Ã?se Marie

2003-01-01

246

Recurrent asthma induced by toluene diisocyanate.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A worker developed toluene diisocyanate induced asthma in 1974. On reassessment, 11 years after leaving the chemical plant where toluene diisocyanate was produced, he had no respiratory symptoms and normal bronchial reactivity in response to methacholine, and showed no reaction when challenged with a subirritant concentration of toluene diisocyanate. He developed asthma within five months of returning to the workplace. Repeat challenge testing showed bronchial hyperreactivity to methacholine ...

Banks, D. E.; Rando, R. J.

1988-01-01

247

Biodegradation of toluene in a trickling filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A trickling filter packed with PVC 16 mm Raschig rings was used to study the degradation of toluene in a polluted air stream, by means of a bacterial biofilm of Pseudomonas putida ATCC 17484. A polluted stream was simulated by blending air with a controlled amount of toluene. The mixing was accomplished in a special mixing chamber designed for that purpose. Induction of the enzymes of the toluene degradative pathway and adaptation of the inoculum were done in batch cultures with mini...

Peixoto, J.; Mota, M.

1998-01-01

248

Hydrotreating of wheat straw in toluene and ethanol.  

Science.gov (United States)

In the present work, wheat straw was hydroliquefied at a temperature of 300°C for 4h in ethanol or toluene in order to obtain bio-components which are useful for fuel purposes. The experiments were performed in a 100mL batch reactor under hydrogen pressure of 70bar. Typically, 2g of straw and 0.1g of catalyst (66%Ni/SiO2-Al2O3) were dispersed in 15g of solvent. The main compounds of the oil produced during the liquefaction of hemicellulose, cellulose and lignin of wheat straw in both solvents are: tetrahydrofuran-2-methanol, 1,2-butanediol and butyrolactone. Besides the mentioned compounds, ethanol favoured the decomposition of bigger molecules to short-chain alcohols such as 1-butanol, 1,2-propanediol and 1,2-ethanediol. Toluene contributes to the production of furans and other cyclic compounds. The light fractions distilled together with the solvent also contain the following: 1-propanol, 2-methyl-cyclopentanone, acetic acid and ethyl acetate. PMID:24787323

Murnieks, Raimonds; Kampars, Valdis; Malins, Kristaps; Apseniece, Lauma

2014-07-01

249

Composition of Toluene-Degrading Microbial Communities from Soil at Different Concentrations of Toluene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Hubert, Casey; Shen, Yin; Voordouw, Gerrit

1999-01-01

250

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

251

(2E-2-Benzylidene-4-ethyl-3,4-dihydronaphthalen-1(2H-one  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C19H18O, the exocyclic C=C double bond has an E configuration. The ethyl substituent on the cyclohexanone ring is in an axial position. The cyclohexanone ring adopts a half-chair conformation, presumably due to conjugation in the benzene ring.

Mohamed Akhazzane

2011-07-01

252

Ethyl 3-oxo-3H-benzo[f]chromene-2-carboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C16H12O4, the chromene ring system is almost planar [maximum deviation = 0.026?(1?Å] and makes dihedral angles of 1.24?(9 and 26.5?(2° with the fused benzene ring and the plane of the ethyl carboxylate group, respectively.

H. K. Arunkashi

2010-10-01

253

Ethyl 3-oxo-3H-benzo[f]chromene-2-carboxyl­ate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C16H12O4, the chromene ring system is almost planar [maximum deviation = 0.026?(1)?Å] and makes dihedral angles of 1.24?(9) and 26.5?(2)° with the fused benzene ring and the plane of the ethyl carboxylate group, respectively.

Vindu Vahini, M.; Devarajegowda, H. C.; Mahadevan, K. M.; Meenakshi, T. G.; Arunkashi, H. K.

2010-01-01

254

N-[(E-(9-Ethyl-9H-carbazol-3-ylmethylidene]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

2010-06-01

255

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

256

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Guan, Jin-tao; Hou, Jian-guo; Zhang, Zhi-yong; Zhao, Si-yin

2010-01-01

257

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

258

[Hydroxy(tosyloxyiodo]benzene Mediated α-Azidation of Ketones  

Directory of Open Access Journals (Sweden)

Full Text Available Reaction of various ketones with [hydroxy(tosyloxyiodo]benzene (HTIB followed by treatment of the α-tosyloxy ketones thus generated in situ with NaN3 offers a one-pot procedure for the synthesis of α-azido ketones. The HTIB used in this conversion may also be generated in situ by using iodosobenzene in combination with p-toluene- sulphonic acid.

Anita Batra

2006-07-01

259

090320 benzene supplementary note final  

…Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It's our job to make sure that air, land and water are looked after by everyone in today's society…

260

090320 benzene supplementary note final  

…Better Regulation Science Programme Science report: SC050021 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It's our job to make sure that air,…

 
 
 
 
261

090320 benzene supplementary note final  

…1 Introduction 1 2 Plant uptake review 2 2.1 Literature search strategy 2 2.2 Plant processes and phytotoxicity 2 2.3 Soil-to-plant concentration factors 3 2.4 Summary and recommendations 5 References 6 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene 1 1 Introduction…

262

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

Directory of Open Access Journals (Sweden)

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

M. L. White

2009-01-01

263

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

Directory of Open Access Journals (Sweden)

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

M. L. White

2008-06-01

264

21 CFR 520.580 - Dichlorophene and toluene capsules.  

Science.gov (United States)

...2009-04-01 false Dichlorophene and toluene capsules. 520.580 Section 520...DRUGS § 520.580 Dichlorophene and toluene capsules. (a) Specifications. ...milligrams of dichlorophene and 60 milligrams of toluene or multiples thereof. (b)...

2009-04-01

265

Studies of the exchange reaction between deuterium oxide and substituted benzenes and of the clustering reaction between water and substituted phenols in chemical ionization mass spectrometry  

International Nuclear Information System (INIS)

Evidence is presented for the protonation site in substituted benzenes. Benzene itself was found to undergo an exchange of ring hydrogens only when protonated. In addition, benzene did not undergo a clustering reaction with water. Based on similar behavior, benzene, toluene, bromobenzene, iodobenzene, fluorobenzene, the xylenes, mesitylene, and the di- and tri-fluorobenzenes were found to protonate on the ring. Nitrobenzene, anisole, phenol, benzaldehyde, and aniline were found to protonate on the substituent. These results are consistent with theoretical predictions for benzene, toluene, and the xylenes. However, discrepancies exist for anisole and phenol (in coomparison to calculations done on the cresols and methylanisoles). The result for anisole also disagrees with a determination by an ICR technique. Kinetics of the exchange reaction for benzene, toluene, the xylenes, and mesitylene were observed. Based on a simple model of consecutive pseudo-first order reactions, rate constants for each step in the reaction sequence were determined. The possibility of a more complicated mechanism is also discussed. The clustering reaction between water molecules and a chemical ionization sample has been studied for a series of substituted phenols. In the nitrophenols, protonation at the nitro group is favored whereas in the methylphenols, ethylphenols, chlorophenols, hydroxphenols, and aminophenols, protonation at the hydroxy group is favored. In the pulsed ionization mode equilibrium effects dominated the spectra obtained in the continuous ionization mode

1977-01-01

266

Regrading 'Chemial toxicity of tritiated toluene'  

International Nuclear Information System (INIS)

When determining the inhalation hazards associated with labelled compounds, such as tritiated toluene, it is necessary to consider chemical toxicity as well as radiotoxicity when handling these compounds. In the case of tritiated toluene chemical toxicity could result in neurological impairment. (U.K.)

1982-01-01

267

ZSM-5 catalyst developed for toluene disproportionation  

Energy Technology Data Exchange (ETDEWEB)

Toluene disproportionation over a new ZSM-5 catalyst formulation shows better activity and stability compared to the current Mobil Toluene disproportionation (MTDP) catalyst. Subsequent adiabatic pilot plant operations confirmed the activity and stability of the new catalyst. This process flexibility is expected to translate into considerable economic advantages for the process using the new catalyst formulation.

Han, S.; Shihabi, D.S. (Mobil Research and Development Corp., Princeton, NJ (USA)); Absil, R.P.L.; Huang, Y.Y.; Leiby, S.M.; Marler, D.O.; McWilliams, J.P. (Mobil Research and Development Corp., Paulsboro, NJ (USA))

1989-08-21

268

Ethyl 4-nitrophenylacetate  

Directory of Open Access Journals (Sweden)

Full Text Available In the asymmetric unit of the title compound, C10H11NO4, there are two crystallographically independent molecules, which are connected via a C—H...O hydrogen bond. The crystal structure is stabilized by this hydrogen bond together with an N—O...? contact [O...Cg 3.297?(5?Å; Cg is the centroid of one of the benzene rings].

Hui-Qing Peng

2008-02-01

269

Methane from benzene in argon dielectric barrier discharge  

International Nuclear Information System (INIS)

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

2013-03-15

270

Methane from benzene in argon dielectric barrier discharge  

Energy Technology Data Exchange (ETDEWEB)

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

Das, Tomi Nath, E-mail: tndas@barc.gov.in [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Dey, G.R., E-mail: grdey@barc.gov.in [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2013-03-15

271

Reduction of benzene in gasoline  

Energy Technology Data Exchange (ETDEWEB)

The benzene concentration in the gasoline pool of a petroleum refinery is decreased by alkylation of the benzene in a catalytic dewaxing reactor using the olefinic by-products from the dewaxing reaction as alkylating agents. The catalytic dewaxing is preferably carried out in the presence of an intermediate pore size zeolite such as ZSM-5 using a distillate or lube boiling range dewaxing feed. The benzene rich feed preferably contains less than about 2% C[sub 7+] aromatics in order to reduce alkylation on non-objectionable species in the reformate. (author)

Harandi, M.N.

1992-09-17

272

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

273

Two cases of acute toluene intoxication.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two patients exposed to high concentrations of toluene in air (greater than 7000 mg/m3) were found at the bottom of a small swimming pool under construction. Their symptoms were stupefaction, paresis, and amnesia. Patient A had been exposed for three hours and patient B for two hours. Ninety minutes after the exposure, the toluene blood concentration in patient A was 4.1 mg/l and in patient B 2.2 mg/l. Urinary ortho-cresol secretion was shown to be a good index of exposure to toluene. After h...

Meulenbelt, J.; Groot, G.; Savelkoul, T. J.

1990-01-01

274

Diethyl 4,5-diphenyl-3,6-bis(trimethylsilyl)benzene-1,2-dicarboxylate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C30H38O4Si2, the two phenyl rings are twisted away from the central benzene ring by 70.28?(8) and 67.42?(7)°. The two Si atoms attached to the benzene ring deviate in opposite directions from the ring plane by 0.258?(3) and 0.206?(3)?Å, respectively. One ethyl group is disordered over two conformations in a 0.568?(5):0.432?(5) ratio. The crystal packing exhibits weak intermolecular C—H...O interactions.

2011-01-01

275

GC/MS analysis of gasoline vapor  

Energy Technology Data Exchange (ETDEWEB)

Methods described in this work provide quantitative determination of benzene, toluene, ethyl benzene, and xylenes in various gasoline samples using gas chromatography/mass spectroscopy procedures. Results were subjected to statistical analysis.

Chen, E.C.M.; Dojahn, J.G.; Haberman, C.A. [Univ. of Houston Clear Lake, Houston, TX (United States)

1995-12-31

276

R-BTEX (Trade Name) Prototype Performance Testing Results. Topical Report, June 1992-April 1993.  

Science.gov (United States)

Emissions of benzene, toluene, ethyl benzene, and the xylene isomers (BTEX) and other volatile organic compounds (VOC) from glycol dehydration units have become a major concern for the natural gas industry as a result of increasing regulatory pressure. Se...

C. O. Rueter D. B. Myers K. S. Fisher P. A. Thompson

1994-01-01

277

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

278

Toluene interactions with the 7 × 7 and sputtered Si(111) surfaces: evidence of methyl-induced and oxygen-enhanced dissociation pathways  

Science.gov (United States)

The effects of methyl substitution on the room-temperature (RT) adsorption and reactivity of toluene and benzene on Si(111)7 × 7 have been investigated by thermal desorption spectrometry (TDS). In particular, the mass 100 (molecular) desorption profile for the low RT exposure of d8-toluene to Si(111)7 × 7 consists of desorption peaks at 370 and 420 K, with the intensity of the peak at 420 K saturating at a lower exposure than the peak at 370 K. The similarities in the exposure dependence of the TDS profiles of toluene and those of benzene suggest a similar adsorption configuration, i.e. a ?-bonded configuration with the ring (near-)parallel to the surface. In addition to the strong molecular desorption, the presence of a relatively weak mass 4 desorption peak at 800 K at higher exposure indicates a weak secondary surface process involving the deposition of D atoms on Si(111)7 × 7 as Si?D. Furthermore, the observation of a similar mass 4 desorption peak at 800 K for the RT exposures of other selectively deuterated toluene isotopes CH 3?C 6D 5 and CD 3?C 6H 5 to Si(111)7 × 7 suggests that there is no exclusive D (H) abstraction at either the aromatic or aliphatic position of the adsorbed olefin molecule. The lack of a corresponding mass 4 desorption profile (at 800 K) for the RT exposure of d6-benzene to Si(111)7 × 7 indicates that the deposition of D atoms on the Si surface originates from the complete dissociation of toluene into C and D atoms, which is likely induced by a methyl-to-surface interaction. Moreover, the overall increase in the mass 4 desorption for the RT exposure of d8-toluene to a sputtered Si surface shows that the sputtered Si surface is more reactive than the 7 × 7 surface. The presence of a new broad mass 4 desorption peak at 540 K suggests an additional pathway by which D 2 molecules evolve directly from the dissociation of adsorbed toluene molecules on the sputtered Si surface. In addition, a RT O 2 post-exposure to d8-toluene adsorbed on Si(111)7 × 7 is found to induce a large increase in the D 2 (mass 4) desorption at 800 K. The increase in the toluene dissociation can be attributed to either a surface-enhanced oxidation or an O 2-induced effect that stabilizes the adsorbed toluene molecules to a higher temperature (>; 350 K) where dehydrogenation and dissociation occur. It is, however, difficult to determine the mechanism for the enhanced dissociation from TDS alone.

MacPherson, C. D.; Leung, K. T.

1995-03-01

279

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate  

International Nuclear Information System (INIS)

Highlights: ? Measurements of activity coefficients at infinite dilution using GLC. ? Forty-two organic solvents and water in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate. ? High selectivity for heptane/thiophene. ? Possible entrainer for different separation processes with water. ? The excess thermodynamic functions and the gas–liquid partition coefficients were calculated. - Abstract: The activity coefficients at infinite dilution, ?13?, for 43 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, ketones, acetonitrile, pyridine, and 1-nitropropane in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][MeSO3] were determined by gas–liquid chromatography at six temperatures within the range (308.15 to 358.15) K. The interaction of these 42 organic compounds and water with the ionic liquid were described with the partial molar excess Gibbs free energy, ?G1E,?, enthalpy ?H1E,?, and entropy Tref?S1E,? at infinite dilution, calculated from the experimental ?13? values obtained over the temperature range. The gas–liquid partition coefficients, KL were calculated for all solutes. The values of the selectivity for few separation problems as heptane/toluene, cyclohexane/benzene, heptane/xylenes and heptane/thiophene were calculated from ?13? and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other ionic liquids based on [EMIM]+ cation. Comparison with the results published earlier for [EMIM][MeSO3] show much lower selectivities in the discussed separation problems. By contrast with the former measured ILs [EMIM][MeSO3] reveals the average selectivity for the separation of aromatics/aliphatics and low capacity for benzene. An interesting high value of selectivity was observed in the separation of thiophene/aliphatics. Very high values of selectivity may be expected in the separation of the azeotropic systems including water. The density of [EMIM][MeSO3] within temperature range from (298.15 to 358.15) K was measured and compared to the literature values.

2012-11-01

280

Atmospheric oxidation mechanism of toluene.  

Science.gov (United States)

The atmospheric oxidation mechanism of toluene initiated by OH radical addition is investigated by quantum chemistry calculations at M06-2X, G3MP2-RAD, and ROCBS-QB3 levels and by kinetics calculation by using transition state theory and unimolecular reaction theory coupled with master equation (RRKM-ME). The predicted branching ratios are 0.15, 0.59, 0.05, and 0.14 for OH additions to ipso, ortho, meta, and para positions (forming R1-R4 adducts), respectively. The fate of R2, R4, and R1 is investigated in detail. In the atmosphere, R2 reacts with O2 either by irreversible H-abstraction to form o-cresol (36%), or by reversible recombination to R2-1OO-syn and R2-3OO-syn, which subsequently cyclize to bicyclic radical R2-13OO-syn (64%). Similarly, R4 reacts with O2 with branching ratios of 61% for p-cresol and 39% for R4-35OO-syn, while reaction of R1 and O2 leads to R1-26OO-syn. RRKM-ME calculations show that the reactions of R2/R4 with O2 have reached their high-pressure limits at 760 Torr and the formation of R2-16O-3O-s is only important at low pressure, i.e., 5.4% at 100 Torr. The bicyclic radicals (R2-13OO-syn, R4-35OO-syn, and R1-26OO-syn) will recombine with O2 to produce bicyclic alkoxy radicals after reacting with NO. The bicyclic alkoxy radicals would break the ring to form products methylglyoxal/glyoxal (MGLY/GLY) and their corresponding coproducts butenedial/methyl-substituted butenedial as proposed in earlier studies. However, a new reaction pathway is found for the bicyclic alkoxy radicals, leading to products MGLY/GLY and 2,3-epoxybutandial/2-methyl-2,3-epoxybutandial. A new mechanism is proposed for the atmospheric oxidation mechanism of toluene based on current theoretical and previous theoretical and experimental results. The new mechanism predicts much lower yield of GLY and much higher yield of butenedial than other atmospheric models and recent experimental measurements. The new mechanism calls for detection of proposed products 2,3-epoxybutandial and 2-methyl-2,3-epoxybutandial. PMID:24901213

Wu, Runrun; Pan, Shanshan; Li, Yun; Wang, Liming

2014-06-26

 
 
 
 
281

9-Ethyl-9H-carbazole-3-carbaldehyde  

Directory of Open Access Journals (Sweden)

Full Text Available The title molecule, C15H13NO, approximates a planar conformation except for the alkyl chain (ethyl group bonded to the N atom with a maximum deviation from the least-squares plane through the 15 planar atoms of 0.120?(2?Å for the O atom. The distance of the formyl O atom from the plane of the carbazole ring is 0.227?(2?Å. The N—C bond lengths in the central ring are significantly different, reflecting the electron-withdrawing properties of the aldehyde group. As a consequence, charge transfer may occur from the carbazole N atom to the substituted benzene ring.

Mao-Sen Yuan

2010-08-01

282

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

International Nuclear Information System (INIS)

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

2008-03-01

283

Primary atmospheric oxidation mechanism for toluene.  

Science.gov (United States)

The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere. PMID:19118482

Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

2009-01-01

284

Gamma-radiolysis of toluene and deuterated toluenes: Pt. 2; Liquid products  

Energy Technology Data Exchange (ETDEWEB)

The {gamma}-radiolysis of liquid toluene (toluene-d{sub 0}), toluene-d{sub 3}, toluene-d{sub 5} and toluene-d{sub 8} has been studied at ambient temperature, with the emphasis of the study being on the liquid products formed during the process. Product identification and measurement were done using high-performance liquid chromatography and gas chromatography combined with mass spectrometry. The dimer and trimer yields accounted for most of the previously obtained ''polymer'' yields of 0.09 {mu}mol for each joule absorbed. For toluene-d{sub 0}, toluene-d{sub 8} and ring-deuterated toluene-d{sub 5}, the major process leading to liquid products was rupture of carbon-hydrogen bonds (mainly on the methyl group but also on the phenyl group). For methyl-deuterated toluene-d{sub 3}, the major process leading to such products was rupture of the carbon-carbon bond joining the methyl group to the ring. These conclusions were confirmed from the isotopic composition of the deuterated dimer and trimer products. (author).

Sagert, N.H.; Quinn, M.J.; Sanipelli, G.G.; Kremers, W. (Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Nuclear Research Establishment); Buchannon, W.D.; Westmore, J.B. (Manitoba Univ., Winnipeg, MB (Canada). Dept. of Chemistry)

1991-01-01

285

Pharmacokinetics of benzene in a human after exposure at about the permissible limit  

Energy Technology Data Exchange (ETDEWEB)

This limited range of experimental human exposure indicates that: 1. In the single experimental subject, the amount of benzene retained in the body 10 hours and more after exposure depends on the multiple of the concentration and duration of exposure. 2. At concentrations about the threshold limit value, the presence of other hydrocarbons does not affect the retention or elimination of benzene. 3. The amount of benzene retained in the body for 10 or more hours is dependent on the energy expenditure of the subject during exposure. There is reason to think that elimination after exposure is similarly affected. 4. While the principal route for elimination of benzene is the metabolite, conjugated phenol, in urine, the proportion eliminated in breath depends on the duration of exposure in the 1- to 8-hour range. 5. Three or four distinct compartments for retaining benzene are apparent and these may be identified with specific groups of organs in the body. 6. Mathematical modelling of the system can provide a reasonably accurate representation of benzene behavior in the body, and should enable dosage to individual or groups of organs to be estimated after occupational exposure. 7. Diurnal variation in the elimination of benzene after exposure may introduce a factor of uncertainty of about two into the prediction of exposure from biological monitoring. 8. Patterns of retention and elimination of toluene are very similar to those of benzene, though the principal metabolite in urine is different, and there may be a limit to the maximum amount that can be excreted by that route due to the relatively low solubility of hippuric acid in aqueous solutions.

Sherwood, R.J.

1988-01-01

286

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

287

Ethyl 4,9-dimethyl-9H-carbazole-3-carboxyl-ate  

Science.gov (United States)

In the title compound, C17H17NO2, the carbazole skeleton includes an eth­oxy­carbonyl group at the 3-position. The indole three-ring system is almost planar [maximum deviation = 0.065?(2)?Å], and the ethyl ester group is inclined to its mean plane by 15.48?(2)°. In the crystal, there are ?–? stacking inter­actions between parallel benzene rings and between parallel benzene and pyrrole rings of adjacent mol­ecules [centroid–centroid distances = 3.9473?(8) and 3.7758?(8)?Å, respectively]. Weak C—H?? inter­actions are also present.

Oncuoglu, Serkan; Dilek, Nefise; Caylak Delibas, Nagihan; Ergun, Yavuz; Hokelek, Tuncer

2014-01-01

288

Ethyl 4,9-dimethyl-9H-carbazole-3-carboxyl-ate.  

Science.gov (United States)

In the title compound, C17H17NO2, the carbazole skeleton includes an eth-oxy-carbonyl group at the 3-position. The indole three-ring system is almost planar [maximum deviation = 0.065?(2)?Å], and the ethyl ester group is inclined to its mean plane by 15.48?(2)°. In the crystal, there are ?-? stacking inter-actions between parallel benzene rings and between parallel benzene and pyrrole rings of adjacent mol-ecules [centroid-centroid distances = 3.9473?(8) and 3.7758?(8)?Å, respectively]. Weak C-H?? inter-actions are also present. PMID:24764961

Oncüo?lu, Serkan; Dilek, Nefise; Caylak Deliba?, Nagihan; Ergün, Yavuz; Hökelek, Tuncer

2014-03-01

289

Biomarkers of environmental benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model. 44 refs., 3 figs., 1 tab.

Weisel, C.; Yu, R.; Roy, A.; Georgopoulos, P. [Environmental and Occupational Health Sciences Institute, Piscataway, NJ (United States)

1996-12-01

290

(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

291

Ruthenium Nanoparticles Intercalated in Hectorite: A Reusable Hydrogenation Catalyst for Benzene and Toluene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The cationic organometallic aqua complexes formed by hydrolysis of [(C6H6)RuCl2]2 in water, mainly [(C6H6)Ru(H2O)3]2+, intercalate into sodium hectorite by ion exchange, replacing the sodium cations between the anionic silicate layers. The yellow hectorite thus obtained reacts in ethanol with molecular hydrogen (50 bar, 100°C) with decomposition of the organometallic aqua complexes to give a bl...

2009-01-01

292

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.

Majid Kakavand

2004-10-01

293

Positronium inhibition by chlorine substituted benzenes in benzene  

International Nuclear Information System (INIS)

Positron lifetime measurements have been performed on CCl4 and 12 different chlorobenzenes in benzene solutions. The solutes cause inhibition of Ps-formation but no quenching. The strongest inhibition effect was caused by CCl4. Among the chlorobenzenes it was found that the isomeric forms of trichlorobenzenes were the most effective inhibitors and hexachlorobenzene had the smallest effect of inhibition. (Auth.)

1976-10-15

294

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

1999-06-01

295

Locating and estimating air emissions from sources of toluene  

Energy Technology Data Exchange (ETDEWEB)

;Table of Contents: Purpose of Document; Overview of Document Contents; Background; Emissions from Toluene Producton; Emissions from Major Uses of Toluene; Emissions from the Use of Toluene-Containing Materials; By-Product Emissions, Processes Unrelated to Production or Use of Toluene; Ambient Air and Stationary Source Test Procedures; Potential Source Categories of Toluene Emissions; Lists of Paint, Ink, and Printing Facilities with Annual Sales Greater Than $1 Million; Toluene Source Categories in Surface Coating Operations; and Summary of Emission Factors Listed In This Document.

1994-03-01

296

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

297

On the atmospheric oxidation of liquid toluene  

Energy Technology Data Exchange (ETDEWEB)

This communication presents preliminary computational results on the interaction between triplet ({sup 3}{Sigma}) and singlet ({sup 1}(1){Sigma}, {sup 1}{Delta}) oxygen molecules with toluene. All three oxygen species form very weak complexes with toluene and all also appear capable of abstracting a benzylic hydrogen atom to form the HO{sub 2} radical. Reaction with singlet molecular oxygen does not convincingly explain the formation of benzylhydroperoxide from toluene residues stored over a long time in brown glass bottles, and it is speculated that this may be a surface-catalysed photochemical reaction. The possible involvement of singlet oxygen molecules in the spontaneous ignition of tyre rubber and of soft coal is discussed briefly and the need for new experimental studies is stressed.

Pritchard, H.O. [York University, New York, ON (Canada). Dept. of Chemistry

2006-07-01

298

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

299

Neurobehavioral performance in workers exposed to toluene.  

Science.gov (United States)

Toluene is widely used in adhesive, printing, painting and petroleum industries in many countries. This study was conducted to examine the effect of chronic exposure to toluene below 100ppm on neurobehavioral performance using a computerized neurobehavioral test battery that emphasizes simple instructions and practice prior to testing. The Behavioral Assessment and Research System (BARS) with Korean language instructions was administered to 54 workers from three different industries: oil refinery, gravure printing, and rubber boat manufacturing. The battery consisted of the following tests: Digit Span (DS), Simple Reaction Time (SRT), Selective Attention (SAT), Finger Tapping (FT), and Symbol Digit (SD). Urine was collected at the end-of-shift to analyze urinary hippuric acid to assess exposure level to toluene. Based on the previous air toluene level, workers were divided into three groups: Low (21 workers, less than 10ppm), Moderate (13 workers, 20-30ppm) and High (20 workers, 70-80ppm) exposure status. Analysis of Covariance (ANCOVA) adjusting for age, education and work duration as covariates, was performed to examine the relationship between the neurobehavioral performance and the exposure groups. Poorer performance of the High exposure group was found on FT-preferred (F=7.034, p=0.002) and SAT latency (F=11.710, p=0.000). Age showed a significant correlation with SD (r=0.417, p=0.002) and SAT number correct (r=-0.460, p=0.000). Years of education and work duration were not significantly correlated with any items. This study supports that toluene exposure below 100ppm is associated with neurobehavioral changes and that high-level toluene exposure could cause not only attention and concentration, but also motor performance deficits. PMID:21783537

Kang, Seong-Kyu; Rohlman, Diane S; Lee, Mi-Young; Lee, Hye-Sil; Chung, Soo-Young; Anger, W Kent

2005-05-01

300

090320 benzene supplementary note final  

…stems and leaves (Collins et al., 2002). Upon entering the leaves, benzene may be lost through transpiration (Burken and Schnoor, 1998) or metabolised. Any resulting metabolites can either be transpired, or retained in the leaves as bound residues (Collins et al., 2002), or incorporated into cell structures…

 
 
 
 
301

090320 benzene supplementary note final  

…various extents - depending on plant species - by loss through volatilisation and transpiration. Gaseous pollutants primarily enter leaves via their stomata, but can also be absorbed through the epidermis of aboveground parts. Surveys of benzene concentrations in plants have found that they tend to accumulate…

302

090320 benzene supplementary note final  

…means that roots are an important organ for metabolism of organic compounds (Collins et al., 2002). Resulting metabolites may be retained in the roots or transported around the plant. These metabolites may be more or less toxic to humans than the original organic chemical. As benzene is only moderately…

303

090320 benzene supplementary note final  

…-plant concentration factors for the produce categories used within the CLEA model. Section 2.3 provides a review of the available literature. It attempts to recommend soil-to-plant concentration factors for use in the CLEA model for deriving Soil Guideline Values (SGVs). Technical Review Benzene - Supplementary…

304

Concentrations and emissions of benzene  

Mar 13, 2008 ... Benzene emissions fell by 72 per cent between 1990 and 2007, and by 41 per ... \\and the main source of 1,3-butadiene is motor vehicle exhausts where 1 ... \\Internet Links: UK National Atmospheric Emissions Inventory (NAEI) ...

305

Ethyl 2-(2,3,4,5,6-Penta­bromo­phen­yl)acetate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compound PBPEA, C10H7Br5O2, has its ethyl acetate portion nearly orthogonal to the benzene ring, with a C—C—C—C torsion angle of 88.3?(5)°. The packing involves an inter­molecular contact with a Br?Br distance of 3.491?(1)?Å, having C—Br?Br angles of 173.4?(2) and 106.0?(2)°. The crystal studied was an inversion twin.

2010-01-01

306

Ethyl trans-12-(pyridin-4-yl)-9,10-ethano-anthracene-11-carboxyl-ate.  

Science.gov (United States)

In the title compound, C24H21NO2, the residues at the central ethyl-ene bridge are trans to each other. The dihedral angles between the pyridine and benzene rings are 67.09?(6) and 61.41?(5)°. In the crystal, centrosymmetrically related mol-ecules are linked into dimers by pairs of C-H?O hydrogen bonds. PMID:24860327

Chandrasekar, S; Sharma Om, Prakash; Srinivasapriyan, V; SureshKumar, M; Ramanathan, C R

2014-05-01

307

Catalytic oxidation of CO, hydrocarbons and ethyl acetate over perovskite-type complex oxides  

International Nuclear Information System (INIS)

The catalytic activity of M"1M"2O_3 perovskite-type complex oxides (M"1 = La, Y, Nd, Yb, M"2 = Co, Mn, Ni) was investigated in the oxidation of CO, propylene, benzene, ethylbenzene, o-xylol and ethyl acetate. Co-containing catalysts were more active than Mn-containing ones in the oxidation. The relationship between the catalytic and adsorption properties was established. 8 refs., 5 figs

1994-01-01

308

Menstrual function in workers exposed to toluene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rates of menstrual disorders were studied in 231 female production workers with high exposure to toluene (mean 88 (range 50-150 ppm) in a factory manufacturing audio speakers and compared with a control group of 58 female production workers in other departments in the same factory who had little or no exposure to toluene (0-25 ppm). An external community control group of 187 working class women under routine care at public maternal and child health centres were also studied. Detailed menstrua...

Ng, T. P.; Foo, S. C.; Yoong, T.

1992-01-01

309

Isolation and Characterization of Toluene-Sensitive Mutants from the Toluene-Resistant Bacterium Pseudomonas putida GM73  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To understand the mechanism underlying toluene resistance of a toluene-tolerant bacterium, Pseudomonas putida GM73, we carried out Tn5 mutagenesis and isolated eight toluene-sensitive mutants. None of the mutants grew in the presence of 20% (vol/vol) toluene in growth medium but exhibited differential sensitivity to toluene. When wild-type cells were treated with toluene (1% [vol/vol]) for 5 min, about 2% of the cells could form colonies. In the mutants Ttg1, Ttg2, Ttg3, and Ttg8, the same tr...

Kim, Kwang; Lee, Sungjin; Lee, Kyunghee; Lim, Dongbin

1998-01-01

310

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

311

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

312

Experimental study of the density and viscosity of 1-ethyl-3-methylimidazolium ethyl sulfate  

International Nuclear Information System (INIS)

Highlights: ? Density of the ionic liquid [EMIM][EtSO4]. ? Viscosity of the ionic liquid [EMIM][EtSO4]. ? Thermodynamic properties of ionic liquid [EMIM][EtSO4]. ? Equation of state of ionic liquid [EMIM][EtSO4]. - Abstract: Density and viscosity of 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO4] have been measured over the temperature range from (283.15 to 413.15) K and at pressures up to 140 MPa and in the temperature range from (283.15 to 373.15) K at 0.1 MPa, respectively. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be (0.01 to 0.08)%, 0.1%, 15 mK, and 0.35%, respectively. The measurements were carried out with an Anton–Paar DMA HPM vibration-tube densimeter and a fully automated SVM 3000 Anton–Paar rotational Stabinger viscometer. The vibration-tube densimeter was calibrated using various reference fluids, double-distilled water, methanol, toluene, and aqueous NaCl solutions. An empiric equation of state for [EMIM][EtSO4] has been developed using the measured (p, ?, T) data. This equation was used to calculate the various thermodynamic properties of the IL and for compare with measured properties (speed of sound and enthalpy). Theoretically based Arrhenius–Andrade and Vogel–Tamman–Fulcher type equations were use to describe of the temperature dependence of measured viscosities for [EMIM][EtSO4]. All measured properties were detailed compared with the reported data by other author.

2012-04-01

313

Toluene exposure increases aminophylline-induced seizure susceptibility in mice  

International Nuclear Information System (INIS)

The effects of toluene on the sensitivity to seizures induced by aminophylline were investigated. Mice were pretreated with an ip injection of corn oil or toluene (100-500 mg/kg) followed by a timed intravenous infusion of aminophylline at various time intervals to assess the seizure thresholds and lethal doses. Toluene increased seizure susceptibility to aminophylline in a dose- and time-dependent manner. Toluene-induced enhancement of seizure susceptibility to aminophylline occurred as early as 30 min and persisted for at least 3 days after a single administration of toluene (500 mg/kg). Treatment of benzaldehyde, one of toluene's metabolites, also showed an increase in the susceptibility to aminophylline. The enhancing effect was also observed in caffeine-induced seizures 1 h, but not 1 day after toluene treatment. These results suggest that individuals with toluene exposure may increase the risk for convulsive and even lethal complications associated with the therapeutic use of aminophylline

2003-12-01

314

Intrinsic bioremediability of an aromatic hydrocarbon-polluted groundwater: diversity of bacterial population and toluene monoxygenase genes  

Energy Technology Data Exchange (ETDEWEB)

The functional and phylogenetic biodiversity of bacterial communities in a benzene, toluene, ethylbenzene and xylene (BTEX)-polluted groundwater was analysed. To evaluate the feasibility of using an air sparging treatment to enhance bacterial degradative capabilities, the presence of degrading microorganisms was monitored. The amplification of gene fragments corresponding to toluene monooxygenase (tmo), catechol 1,2-dioxygenase, catechol 2,3-dioxygenase and toluene dioxygenase genes in DNA extracted directly from the groundwater samples was associated with the presence of indigenous degrading bacteria. Five months of air injection reduced species diversity in the cultivable community (as calculated by the Shannon-Weaver index), while little change was noted in the degree of biodiversity in the total bacterial community, as characterised by denaturing gradient gel electrophoresis (DGGE) analysis. BTEX-degrading strains belonged to the genera Pseudomonas, Microbacterium, Azoarcus, Mycobacterium and Bradyrhizobium. The degrading capacities of three strains in batch liquid cultures were also studied. In some of these microorganisms different pathways for toluene degradation seemed to operate simultaneously. Pseudomonas strains of the P24 operational taxonomic unit, able to grow only on catechol and not on BTEX, were the most abundant, and were present in the groundwater community at all stages of treatment, as evidenced both by cultivation approaches and by DGGE profiles. The presence of different tmo-like genes in phylogenetically distant strains of Pseudomonas, Mycobacterium and Bradyrhizobium suggested recent horizontal gene transfer in the groundwater. (orig.)

Cavalca, L.; Dell' Amico, E.; Andreoni, V. [Dipt. di Scienze e Tecnologie Alimentari e Microbiologiche, Univ. degli Studi di Milano, Milan (Italy)

2004-07-01

315

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. The absence of a toluene dihydrodiol intermediate or toluene dioxygenase and toluene dihydrodiol de...

M. S. Shields S. O. Montgomery P. J. Chapman S. M. Cuskey P. H. Pritchard

1989-01-01

316

Structure of Diffusion Flames Burning Pure, Binary, and Ternary Solutions of Methanol, Heptane, and Toluene,  

Science.gov (United States)

The structure of counterflow diffusions flames burning heptane, toluene, binary solutions of methanol and toluene, and heptane and toluene, and ternary solutions of methanol, heptane, and toluene is characterized in the vicinity of extinction. Composition...

A. Hamins K. Seshadri

1987-01-01

317

Trends in electron-ion dissociative recombination of benzene analogs with functional group substitutions: Negative Hammett ?para values  

Science.gov (United States)

An in-depth study of the effects of functional group substitution on benzene's electron-ion dissociative recombination (e-IDR) rate constant has been conducted. The e-IDR rate constants for benzene, biphenyl, toluene, ethylbenzene, anisole, phenol, and aniline have been measured using a Flowing Afterglow equipped with an electrostatic Langmuir probe (FALP). These measurements have been made over a series of temperatures from 300 to 550 K. A relationship between the Hammett ?para values for each compound and rate constant has indicated a trend in the e-IDR rate constants and possibly in their temperature dependence data. The Hammett ?para value is a method to describe the effect a functional group substituted to a benzene ring has upon the reaction rate constant.

Osborne, David; Lawson, Patrick Andrew; Adams, Nigel; Dotan, Itzhak

2014-06-01

318

Laser photochemical synthesis of benzene and its derivatives. [Substituted benzenes  

Energy Technology Data Exchange (ETDEWEB)

A cw CO/sub 2/ tunable laser is employed to irradiate an allyl halide selected from allyl chloride, allyl bromide, allyl fluoride, 2-methyl-3-chloropropene, and 2,3-dichloropropene and contained in one or more reaction cells at a predetermined pressure. A predetermined power level from about 25 to 150 watts, an irradiating time from about 0.2 second to about 60 seconds, and a selected radiation line for example P(36), P(32), P(26), or P(22) (that is resonant with an absorption band of the selected allyl halide) are employed to achieve dissociation of the selected allyl halide and to achieve a laser-induced photochemical synthesis of benzene and substituted benzenes.

McDonald, J.K.; Merritt, J.A.

1983-12-27

319

The rotation-torsion contour of the 2668 Å origin band of toluene. High-resolution 295 K absorption spectrum  

Science.gov (United States)

The 2668 Å vibrational origin band of toluene was measured and analyzed using an asymmetric-top/free-internal-rotor model. The change in the methyl group geometry between the ground ( eA' 1) and the excited eA? 1 ( ?? ?) state was found to be slight. Rough values found for the changes in the phenyl frame rotational constants are similar to those for other monosubstituted benzenes with substituents lacking lone-pair electrons. The torsional structure in the toluene origin band is blue-degraded whereas the rotational structure in each ? m = 0 torsional manifold of transitions is red-degraded. Deconvolution of the torsional structure in the calculated contour shows that strong R-branch heads for transitions emanating from each torsional level of the ground state persist in the experimental contour for 0 ? | m| ? 12.

Leugers, M. A.; Seliskar, C. J.

1982-01-01

320

Effect of methyl substitution of benzene on the percutaneous absorption and skin irritation in hairless rats.  

Science.gov (United States)

The permeation rate and skin retention of benzene and methylbenzenes were assessed in vitro using hairless rat skin. The effects of unocclusive dermal exposures of these chemicals (15 microl every 2h for 8h a day for 4 days) on the transepidermal water loss (TEWL), erythema and skin histopathology were measured in CD hairless rats. The expression of IL-1 alpha and TNF-alpha in the skin and blood were measured at the end of dermal exposures. The flux of benzene was about 1.5-, 2.5- and 80-fold higher than toluene, xylene and tetramethyl benzene isomers (TMB), respectively, and the values were inversely correlated with molecular weight (r(2)=0.7455) and logoctanol-water partition coefficient (r(2)=0.7831). The retention of chemicals in stratum corneum (SC) was in the order of TMB>xylene>toluene approximately benzene. The TEWL and erythema data demonstrated that the irritation was in the following order: TMB>xylene>benzene. The histo-pathological examination showed that xylene and TMB induced granulocyte infiltration, swelling of the epidermis, and extensive disruption and damage of stratum corneum. Likewise, the expression of IL-1 alpha in the blood and TNF-alpha in the skin after dermal exposures was higher for TMB followed by xylene and benzene compared to control. In conclusion, the aromatic hydrocarbon chemicals induced cumulative irritation upon low-level repeat exposures for a 4-day period and the irritation increased with the number of methyl groups of benzene. The affinity of the chemical to SC and their gradual accumulation in the skin in the present study is the reason for the differences in the skin irritation profiles of different aromatic chemicals. Our ultimate goal is to develop a biologically based model that connects skin retention of chemical to the skin irritation response. The findings of the present study will be helpful in understanding the role of these chemicals in the jet fuel and various petroleum based fuels in inducing skin irritation response. PMID:16087301

Ahaghotu, E; Babu, R J; Chatterjee, A; Singh, M

2005-12-15

 
 
 
 
321

Disproportionation of a toluene fraction of liquid products of pyrolysis  

Energy Technology Data Exchange (ETDEWEB)

Comparative data are obtained on disproportionation of reactive toluene and toluene fraction of 95-120/sup 0/ pyrobenzine, showing the possibility of direct use of the industrial toluene fraction for the disproportionation process, and the advisability of including it as a possible variant in an integrated system of liquid pyrolysis product processing.

Garnish, A.M.; Druzhinina, I.A.; Khairova, L.A.; Kuz' mina, V.A.

1980-01-01

322

Assimilation and conversion of toluene by higher plants  

Energy Technology Data Exchange (ETDEWEB)

It was established that higher plants are capable of absorbing and detoxifying toluene. Both the roots and the aerial organs have this ability. A number of toluene metabolites (organic acids, amino acids, and sugars) were isolated and identified. It was shown that organic acids are the primary products of cleavage of the toluene aromatic ring. 6 references, 3 tables.

Durmishidze, S.V.; Ugrekhelidze, D.Sh.; Dzhikiya, A.N.

1974-01-01

323

Solvent extraction-spectrophotometric determination of boron with 3,5-di-tert-butylcatechol and ethyl violet  

Energy Technology Data Exchange (ETDEWEB)

Boric acid and 3,5-di-tert-butylcathechol formed a complex anion at pH 6.3-8.7 which was extracted into toluene as an ion pair with ethyl violet (EV); the excess EV coextracted into toluene was removed by adding 3% hydrogen peroxide. Boron was determined spectrophotometrically by measuring the absorbance of EV of the ion pair in toluene at 610 nm. The calibration curve was linear within a range of 0.043 ..mu..g of boron, and the molar absorptivity was 10.5 x 10/sup 4/ L mol/sup -1/ cm/sup -1/. This method, using the new complexing agent, was applied to the determination of boron in seawater and found to be appreciably satisfactory compared with other methods. 7 references, 3 tables, 2 figures.

Oshima, M.; Motomizu, S.; Toei, K.

1984-01-01

324

Diethyl 4,5-diphenyl-3,6-bis­(trimethyl­sil­yl)benzene-1,2-dicarboxyl­ate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C30H38O4Si2, the two phenyl rings are twisted away from the central benzene ring by 70.28?(8) and 67.42?(7)°. The two Si atoms attached to the benzene ring deviate in opposite directions from the ring plane by 0.258?(3) and 0.206?(3)?Å, respectively. One ethyl group is disordered over two conformations in a 0.568?(5):0.432?(5) ratio. The crystal packing exhibits weak inter­molecular C—H?O inter­actions.

2011-01-01

325

Slow Neutron Scattering by Benzene  

International Nuclear Information System (INIS)

We have calculated the scattering of slow neutrons by the benzene molecule. The calculations are carried out within the framework of the time dependent formalism of Zemach and Glauber. Detailed account is taken of the effects of the molecular vibrations on the neutron scattering. Among the results explicitly calculated are the slow neutron total scattering cross-section as a function of energy and the energy angular distribution of singly scattered sections. (author)

1963-01-01

326

(?5-Penta­methyl­cyclo­penta­dien­yl)(?6-p-toluene­sulfonamide)ruthenium(II) tetra­phenyl­borate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The crystal structure of the title compound, [Ru(C10H15)(C7H9NO2S)]C24H20B, has been determined as part of our investigation into the structural and biological properties of organometallic RuII–arene–Cp* complex salts of the type [R-PhRuCp*]+·X ? (where Cp* is penta­methyl­cyclo­penta­diene). Tethering the RuCp* group to the benzene ring of p-toluene­sulfonamide results in only minor changes to the mol­ecular geometry of the sulfonamide, but, together with cryst...

Loughrey, Bradley T.; Williams, Michael L.; Poulsen, Sally-ann; Healy, Peter C.

2008-01-01

327

Gene components responsible for discrete substrate specificity in the metabolism of biphenyl (bph operon) and toluene (tod operon).  

Digital Repository Infrastructure Vision for European Research (DRIVER)

bph operons coding for biphenyl-polychlorinated biphenyl degradation in Pseudomonas pseudoalcaligenes KF707 and Pseudomonas putida KF715 and tod operons coding for toluene-benzene metabolism in P. putida F1 are very similar in gene organization as well as size and homology of the corresponding enzymes (G. J. Zylstra and D. T. Gibson, J. Biol. Chem. 264:14940-14946, 1989; K. Taira, J. Hirose, S. Hayashida, and K. Furukawa, J. Biol. Chem. 267:4844-4853, 1992), despite their discrete substrate r...

Furukawa, K.; Hirose, J.; Suyama, A.; Zaiki, T.; Hayashida, S.

1993-01-01

328

Toluene Levels in Blood and Brain of Rats as a Function of Toluene Level in Inspired Air.  

Science.gov (United States)

The relationship of toluene concentration in blood and brain to the concentration of toluene in inspired air has not been explicitly studied. Sixty rats were exposed by inhalation to 50, 100, 500, or 1000 ppm toluene for 3 hr. Immediately following exposu...

V. A. Benignus K. E. Muller J. A. Graham C. N. Barton

1984-01-01

329

Behavior of toluene added to sludge-amended soils  

Energy Technology Data Exchange (ETDEWEB)

Toluene is a priority pollutant that can be introduced to soils in a variety of wastes, including some municipal sludges. Laboratory experiments were conducted to study the behavior of toluene in two soils in the presence and absence of municipal sludge. Sludge additions increased toluene adsorption in two soils because of increased organic C content. The source of organic C (soil or sludge) and soil clay content also influenced toluene adsorption. Toluene adsorption-desorption was reversible in one soil, but slightly hysteretic in the other soil. An air-flow incubation system was used to evaluate toluene volatilization and degradation. The primary fate of surface-applied toluene in both soils was volatilization. Toluene volatilization rates were independent of sludge treatments. Toluene degradation was negligible in all treatments because of rapid volatilization losses. Despite increased toluene adsorption in the presence of sludge and reduced volatilization in saturated soils, gaseous transfer dominated all soils and treatments so that no toluene remained after 10 d.

Jin, Y.; O' Connor, G.A.

1990-01-01

330

Effect of trichloroethylene (TCE) and toluene concentrations on TCE and toluene biodegradation and the population density of TCE and toluene degraders in soil.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Toluene is one of several cosubstrates able to support the cometabolism of trichloroethylene (TCE) by soil microbial communities. Indigenous microbial populations in soil degraded TCE in the presence, but not the absence, of toluene after a 60- to 80-h lag period. Initial populations of toluene and TCE degraders ranged from 0.2 x 10(3) to 4 x 10(3) cells per g of soil and increased by more than 4 orders of magnitude after the addition of 20 micrograms of toluene and 1 microgram of TCE per ml ...

Mu, D. Y.; Scow, K. M.

1994-01-01

331

Inquinamento outdoor - indoor da toluene e xileni  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Obiettivi: il toluene e lo xilene (TX) rappresentano alcuni degli inquinanti aromatici più diffusi perché ubiquitari. Poiché la loro contaminazione può determinare effetti tossico-nocivi, lo scopo di questo studio è stato quello di valutare la concentrazione dei TX in alcuni distretti di Roma, al fine di accertare l’esposizione della popolazione e promuovere il “Risk Management” dell’inquinamento da idrocarburi in ambiente.

...

Moscato, U.; La Torre, G.; La Torre, F.; Pierangelini, A.; Ricciardi, G.

2003-01-01

332

Developmental toxicity of prenatal exposure to toluene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Organic solvents have become ubiquitous in our environment and are essential for industry. Many women of reproductive age are incresingly exposed to solvents such as toluene in occupational settings (ie, long-term, lowconcentration exposures) or through inhalant abuse (eg, episodic, binge exposures to high concentrations). The risk for teratogenic outcome is much less with low to moderate occupational solvent exposure compared with the greater potential for adverse pregnancy outcomes, develop...

Bowen, Scott E.; Hannigan, John H.

2006-01-01

333

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

2011-03-01

334

The substituent effect on benzene dications.  

Science.gov (United States)

It was recently postulated that the benzene ring and its 4n + 2 ?-electron analogues are resistant to the substituent effect due to the fact that such systems tend to retain their delocalized character. Therefore, the 4n ?-electron dicationic form of benzene should appear to be less resistant to the substituent effect, as compared with its parent neutral molecule. For this reason the effect of substitution on the dicationic form of benzene was thoroughly investigated and the consequences of single and double substitution (of para- and meta-type) were assessed by means of several parameters, including various aromaticity indices and the Substituent Effect Stabilization Energy (SESE) parameter. It is shown that, distinct from neutral benzene, its dicationic form is much more sensitive to the substitution. However, the dicationic benzene itself, as a moiety with a significant deficit of electrons, will be considered as a strongly electron-withdrawing centre, thus interacting in a cooperative way with electron-donating substituents and in an anticooperative way with electron-withdrawing substituents. Clear differences between singlet- and triplet-state dicationic forms of benzene were also found. Triplet state structures seem to be significantly more delocalized, and as a consequence less sensitive to the substituent effect than the singlet state structures. Finally, the para- and meta-type substitution was investigated and it was found that the disubstituted dicationic benzene exhibits significantly different behaviour from that of neutral benzene. Although the difference between para- and meta-substitution can be found for dicationic benzene, the mechanism responsible for such an observation is different from that present in neutral benzene. Finally, it is shown how and why double ionization of benzene reduces its aromatic character in the singlet dication whereas aromaticity is essentially conserved in the triplet dication. The above findings highlight that in the case of charged analogues of benzene the aromaticity indices can be misleading and are to be used with great precaution. PMID:24469543

Palusiak, Marcin; Domaga?a, Ma?gorzata; Dominikowska, Justyna; Bickelhaupt, F Matthias

2014-03-14

335

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

336

Inquinamento outdoor - indoor da toluene e xileni  

Directory of Open Access Journals (Sweden)

Full Text Available

Obiettivi: il toluene e lo xilene (TX rappresentano alcuni degli inquinanti aromatici più diffusi perché ubiquitari. Poiché la loro contaminazione può determinare effetti tossico-nocivi, lo scopo di questo studio è stato quello di valutare la concentrazione dei TX in alcuni distretti di Roma, al fine di accertare l’esposizione della popolazione e promuovere il “Risk Management” dell’inquinamento da idrocarburi in ambiente.

Metodi: il campionamento dei TX è stato realizzato in tre fasi, utilizzando campionatori passivi a simmetria radiale, disposti in circa 150 siti, per un tempo di esposizione di due giorni. I campioni sono stati desorbiti in solvente ed analizzati in Gas-Cromatografia-FID. I dati sono stati elaborati attraverso la statistica descrittiva ed analisi del coefficiente di correlazione tra i livelli di TX outdoor- indoor. È stata inoltre condotta un’analisi di regressione lineare multipla (metodo backward elimination con i valori di TX indoor come variabili dipendenti e come covariate i valori di TX outdoor, la velocità dell’aria, la temperatura, l’umidità relativa e la presenza di fumatori. Risultati: i valori medi delle concentrazioni di toluene (outdoor 1,43–461,6 mg/m3; indoor 16,7- 185,3 mg/m3 e dello xilene (outdoor 1,1–72,2 mg/m3; indoor 14,8-320,2 mg/m3 indicano un coefficiente di correlazione di 0.637 (primo periodo e 0.683 (terzo periodo di misurazione fra valori di toluene outdoor-indoor mentre, rispettivamente, di 0.928 e 0.955 per lo xilene, con elevatissimi livelli di significatività statistica per ambedue (p ‹ 0.0001. L’analisi multivariata mostra una stretta relazione tra i valori outdoor-indoor dei TX. Mentre i livelli di toluene indoor sono circa un quinto dei valori registrati all’esterno, i livelli di xilene indoor, altresì, sono da due a quattro volte maggiori dei valori outdoor.

Conclusioni: i risultati suggeriscono che l’esposizione a toluene e xilene non dovrebbe essere sottostimata in quanto responsabile di effetti prevalentemente cronici sulla popolazione esposta, in particolare negli ambienti confinati.

U. Moscato

2003-05-01

337

Benzodiazepine-like discriminative stimulus effects of toluene vapor.  

Science.gov (United States)

In vitro studies show that the abused inhalant toluene affects a number of ligand-gated ion channels.The two most consistently implicated of these are ?-aminobutyric acid type A(GABAA) receptors which are positively modulated by toluene and N-methyl-D-aspartate(NMDA) receptors which are negatively modulated by toluene. Behavioral studies also suggest an interaction of toluene with GABAA and/or NMDA receptors but it is unclear if these receptors underlie the abuse-related intoxicating effects of toluene. Seventeen B6SJLF1/J mice were trained using a two-choice operant drug discrimination procedure to discriminate 10 min of exposure to 2000 ppm toluene vapor from 10 min of exposure to air. The discrimination was acquired in a mean of 65 training sessions. The stimulus effects of 2000 ppm toluene vapor were exposure concentration-dependent but rapidly diminished following the cessation of vapor exposure. The stimulus effects of toluene generalized to the chlorinated hydrocarbon vapor perchloroethylene but not 1,1,2-trichloroethane nor the volatile anesthetic isoflurane. The competitive NMDA antagonist CGS-19755, the uncompetitive antagonist dizocilpine and the glycine-site antagonist L701,324 all failed to substitute for toluene. The classical nonselective benzodiazepines midazolam and chlordiazepoxide produced toluene-like stimulus effects but the alpha 1 subunit preferring positive GABAA modulator zaleplon failed to substitute for toluene. The barbiturates pentobarbital and methohexital and the GABAA positive modulator neurosteroid allopregnanolone did not substitute for toluene. These data suggest that the stimulus effects of toluene may be at least partially mediated by benzodiazepine-like positive allosteric modulation of GABAA receptors containing alpha 2, 3 or 5 subunits. PMID:24436974

Shelton, Keith L; Nicholson, Katherine L

2013-11-15

338

Novel Pathway of Toluene Catabolism in the Trichloroethylene-Degrading Bacterium G4  

Digital Repository Infrastructure Vision for European Research (DRIVER)

o-Cresol and 3-methylcatechol were identified as successive transitory intermediates of toluene catabolism by the trichloroethylene-degrading bacterium G4. The absence of a toluene dihydrodiol intermediate or toluene dioxygenase and toluene dihydrodiol dehydrogenase activities suggested that G4 catabolizes toluene by a unique pathway. Formation of a hybrid species of 18O- and 16O-labeled 3-methylcatechol from toluene in an atmosphere of 18O2 and 16O2 established that G4 catabolizes toluene by...

Shields, Malcolm S.; Montgomery, Stacy O.; Chapman, Peter J.; Cuskey, Stephen M.; Pritchard, P. H.

1989-01-01

339

Vapor-liquid equilibria of binary mixtures with ethyl tert-butyl ether  

Energy Technology Data Exchange (ETDEWEB)

In this work P-T-x-y vapor-liquid equilibria were obtained for ethyl tert-butyl ether (ETBE) + toluene at temperatures of 273.15, 311.15, and 333.15 K and for 2-methylbutane (isopentane) + ETBE at temperatures of 293.15 and 303.15 K. These mixtures are found to be almost ideal, and the reported data are well described using a Peng-Robinson equation of state, modified by Stryjek and Vera with the van der Waals one-fluid mixing rule.

Steinhagen, V. (Technische Univ., Berlin (Germany). Inst. fuer Thermodynamik und Reaktionstechnik); Sandler, S.I. (Univ. of Delaware, Newark, DE (United States). Dept. of Chemical Engineering)

1994-07-01

340

Ferromagnetic resonance spectroscopy of carboxylated cobalt-containing nanocomposite ethyl methacrylate/acrylic acid copolymers  

Science.gov (United States)

We have used ferromagnetic resonance spectroscopy to study the effect of the concentration of cobalt nanoparticles (5-9 nm) incorporated into ethyl methacrylate/acrylic acid copolymers (monomer ratios 100:1 and 10:1) on the magnitude of the resonant field in ferromagnetic resonance and on the effective magnetization of thin-film samples of these nanocomposite polymer materials. The cobalt nanoparticles were obtained by thermolysis of Co2(CO)8 in 5% solutions of the indicated copolymers in toluene. From the solutions obtained, we prepared films of thickness 1 ?m on aluminum substrates.

Voytsihovskaya, S. A.; Sokolov, M. E.; Panyushkin, V. T.; Gromov, P. Yu.; Shcherbina, A. A.; Matveev, V. V.

2013-01-01

 
 
 
 
341

Evaluation of the performance of a passive sampler in the monitoring of benzene and other volatile aromatic compounds in urban and indoor sites  

International Nuclear Information System (INIS)

Laboratory and field tests have been performed on a new passive device, properly designed for the collection of volatile organic compounds from ambient air on an active charcoal layer. Tests performed in order to determine accuracy and precision, response linearity and employment limits show that this device may be helpful in long and medium-time determinations of BTX (benzene, toluene and xylenes) in the atmosphere. The sampler is optimised for a four weeks sampling in open air

1999-01-01

342

Systems biology of human benzene exposure  

Science.gov (United States)

Toxicogenomic studies, including genome-wide analyses of susceptibility genes (genomics), gene expression (transcriptomics), protein expression (proteomics), and epigenetic modifications (epigenomics), of human populations exposed to benzene are crucial to understanding gene-environment interactions, providing the ability to develop biomarkers of exposure, early effect and susceptibility. Comprehensive analysis of these toxicogenomic and epigenomic profiles by bioinformatics in the context of phenotypic endpoints, comprises systems biology, which has the potential to comprehensively define the mechanisms by which benzene causes leukemia. We have applied this approach to a molecular epidemiology study of workers exposed to benzene. Hematotoxicity, a significant decrease in almost all blood cell counts, was identified as a phenotypic effect of benzene that occurred even below 1ppm benzene exposure. We found a significant decrease in the formation of progenitor colonies arising from bone marrow stem cells with increasing benzene exposure, showing that progenitor cells are more sensitive to the effects of benzene than mature blood cells, likely leading to the observed hematotoxicity. Analysis of transcriptomics by microarray in the peripheral blood mononuclear cells of exposed workers, identified genes and pathways (apoptosis, immune response, and inflammatory response) altered at high (>10ppm) and low (<1ppm) benzene levels. Serum proteomics by SELDI-TOF-MS revealed proteins consistently down-regulated in exposed workers. Preliminary epigenomics data showed effects of benzene on the DNA methylation of specific genes. Genomic screens for candidate genes involved in susceptibility to benzene toxicity are being undertaken in yeast, with subsequent confirmation by RNAi in human cells, to expand upon the findings from candidate gene analyses. Data on these and future biomarkers will be used to populate a large toxicogenomics database, to which we will apply bioinformatic approaches to understand the interactions among benzene toxicity, susceptibility genes, mRNA, and DNA methylation through a systems biology approach.

Zhang, Luoping; McHale, Cliona M.; Rothman, Nathaniel; Li, Guilan; Ji, Zhiying; Vermeulen, Roel; Hubbard, Alan E.; Ren, Xuefeng; Shen, Min; Rappaport, Stephen M.; North, Matthew; Skibola, Christine F.; Yin, Songnian; Vulpe, Christopher; Chanock, Stephen J.; Smith, Martyn T.; Lan, Qing

2010-01-01

343

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

344

21 CFR 172.868 - Ethyl cellulose.  

Science.gov (United States)

...2009-04-01 2009-04-01 false Ethyl cellulose. 172.868 Section 172.868 Food and...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...

2009-04-01

345

Impact of trichloroethylene and toluene on nitrogen cycling in soil.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of trichloroethylene (TCE) and toluene on soil nitrogen-cycling activities were examined. Ammonium oxidation potential (AOP) was reduced after incubation with as little as 1 microgram of TCE ml-1, and the effects were generally greater when toluene was present and increased with longer exposure. Arginine ammonification potential and denitrification enzyme activity were constant regardless of TCE concentration or the presence of toluene, while nitrite oxidation potential (NOP) exhi...

Fuller, M. E.; Scow, K. M.

1997-01-01

346

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

347

Antipyrine clearance during experimental and occupational exposure to toluene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 u...

Døssing, M.; Baelum, J.; Lundqvist, G. R.

1983-01-01

348

Toluene mediated oxidative stress and granulo-monocytopoiesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 erythroc...

Boži? Tatjana P.; Z?, Stevanovic? Jelka; 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

349

Anaerobic degradation of toluene by a denitrifying bacterium.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO2, and 29% was assimilated into biomass. The oxidation of toluene to CO2 was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was toler...

Evans, P. J.; Mang, D. T.; Kim, K. S.; Young, L. Y.

1991-01-01

350

Anaerobic degradation of toluene by a denitrifying bacterium  

Energy Technology Data Exchange (ETDEWEB)

A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO{sub 2}, and 29% was assimilated into biomass. The oxidation of toluene to CO{sub 2} was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 {mu}mol min{sup {minus}1} liter{sup {minus}1} (56 nmol min{sup {minus}1} mg of protein{sup {minus}1}) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene.

Evans, P.J.; Mang, D.T.; Kwang Shin Kim; Young, L.Y. (New York Univ. Medical Center, NY (United States))

1991-04-01

351

Decomposition of toluene in a gliding arc discharge plasma reactor  

Science.gov (United States)

The decomposition of toluene in a gliding arc discharge (glidarc) was performed and studied. Experimental results indicate that the glidarc technology can effectively decompose toluene molecules and has bright prospects of being applied as an alternative tool to decompose volatile organic compounds. It is found that a change in the electrode material had an insignificant effect on the toluene removal efficiency. The toluene removal efficiency increases with increasing inlet gas temperature. The water vapor present in the gas mixture has a favorable effect on the toluene decomposition in the plasma. The energy efficiency is 29.46 g (kWh-1) at a relative humidity of 50% and a specific energy input of 0.26 kWh m-3, which is higher than other types of non-thermal plasmas. Too much or too little oxygen content does not favor toluene decomposition. The major gas phase products detected by FT-IR from the decomposition of toluene with air participation were CO, CO2, H2O and NO2. Some brown depositions were found on the surface of the electrodes, which were polar oxygenous and nitrogenous compounds determined by the GC-MS analysis, such as benzaldehyde, benzoic acid, quinine and nitrophenol from the reaction of toluene with radicals. A possible mechanism for toluene destruction via glidarc technology is proposed and summarized.

Du, Chang Ming; Yan, Jian Hua; Cheron, Bruno

2007-11-01

352

Decomposition of toluene in a gliding arc discharge plasma reactor  

Energy Technology Data Exchange (ETDEWEB)

The decomposition of toluene in a gliding arc discharge (glidarc) was performed and studied. Experimental results indicate that the glidarc technology can effectively decompose toluene molecules and has bright prospects of being applied as an alternative tool to decompose volatile organic compounds. It is found that a change in the electrode material had an insignificant effect on the toluene removal efficiency. The toluene removal efficiency increases with increasing inlet gas temperature. The water vapor present in the gas mixture has a favorable effect on the toluene decomposition in the plasma. The energy efficiency is 29.46 g (kWh{sup -1}) at a relative humidity of 50% and a specific energy input of 0.26 kWh m{sup -3}, which is higher than other types of non-thermal plasmas. Too much or too little oxygen content does not favor toluene decomposition. The major gas phase products detected by FT-IR from the decomposition of toluene with air participation were CO, CO{sub 2}, H{sub 2}O and NO{sub 2}. Some brown depositions were found on the surface of the electrodes, which were polar oxygenous and nitrogenous compounds determined by the GC-MS analysis, such as benzaldehyde, benzoic acid, quinine and nitrophenol from the reaction of toluene with radicals. A possible mechanism for toluene destruction via glidarc technology is proposed and summarized.

Du Changming [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Yan Jianhua [Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027 (China); Cheron, Bruno [UMR 6614 (CORIA), University of Rouen, 76821 Mont Saint Aignan (France)

2007-11-15

353

Decomposition of toluene in a gliding arc discharge plasma reactor  

International Nuclear Information System (INIS)

The decomposition of toluene in a gliding arc discharge (glidarc) was performed and studied. Experimental results indicate that the glidarc technology can effectively decompose toluene molecules and has bright prospects of being applied as an alternative tool to decompose volatile organic compounds. It is found that a change in the electrode material had an insignificant effect on the toluene removal efficiency. The toluene removal efficiency increases with increasing inlet gas temperature. The water vapor present in the gas mixture has a favorable effect on the toluene decomposition in the plasma. The energy efficiency is 29.46 g (kWh-1) at a relative humidity of 50% and a specific energy input of 0.26 kWh m-3, which is higher than other types of non-thermal plasmas. Too much or too little oxygen content does not favor toluene decomposition. The major gas phase products detected by FT-IR from the decomposition of toluene with air participation were CO, CO2, H2O and NO2. Some brown depositions were found on the surface of the electrodes, which were polar oxygenous and nitrogenous compounds determined by the GC-MS analysis, such as benzaldehyde, benzoic acid, quinine and nitrophenol from the reaction of toluene with radicals. A possible mechanism for toluene destruction via glidarc technology is proposed and summarized

2007-11-01

354

Percutaneous absorption of benzene: research and regulation  

Energy Technology Data Exchange (ETDEWEB)

This article attempts to review several aspects of the regulation of benzene in the United States with an emphasis on percutaneous penetration (absorption of benzene into the skin). The author's purpose is not merely to highlight a regulatory crisis encountered by the American rubber industry, but to also provide a vivid example of how toxic substances and carcinogens are regulated in the United States. This paper, therefore, will address the following three areas: first, a chronology of benzene regulation, both voluntary and mandatory; second, a brief review of the early literature on the percutaneous penetration of benzene; and third, a summary of recent studies on benzene penetration which were conducted under the auspices of the American rubber industry.

Ryan, F.T.

1981-01-01

355

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

Energy Technology Data Exchange (ETDEWEB)

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

Ghantous, H.; Dencker, L.; Danielsson, B.R.G (Department of Toxicology, Uppsala University, Uppsala (Sweden)); Gabrielsson, J. (Department of Biopharmaceutics and Pharmacokinetics, Uppsala University, Uppsala (Sweden)); Bergman, K. (Toxicology Laboratory, National Swedish Food Administration, Uppsala (Sweden))

1990-01-01

356

Permeation of polymeric materials by toluene  

Energy Technology Data Exchange (ETDEWEB)

The permeation of toluene through protective clothing materials composed of butyl, butyl-coated nomex, neoprene, and polyvinyl alcohol was tested at 25/sup 0/C and 45/sup 0/C with the use of ASTM method F-739. Butyl exhibited breakthrough of 18 min at 25/sup 0/C and 11 min at 45/sup 0/ C. Butyl nomex exhibited breakthrough times of 11 min and 25/sup 0/C and 6 min at 45/sup 0/C. PVA showed no breakthrough in 20 hr. The steady-state permeation rates and the diffusion coefficients were determined.

Vahdat, N.

1987-02-01

357

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

International Nuclear Information System (INIS)

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

1977-01-01

358

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

2007-04-26

359

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

360

Apparent Benzene Solubility in Tetraphenylborate Slurries  

International Nuclear Information System (INIS)

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

1997-01-01

 
 
 
 
361

75 FR 52768 - Withdrawal of Approval of New Animal Drug Applications; Dichlorophene and Toluene Capsules  

Science.gov (United States)

...Drug Applications; Dichlorophene and Toluene Capsules AGENCY: Food and Drug Administration...NADAs) for use of dichlorophene and toluene deworming capsules for cats and dogs...101-497 for TINY TIGER (dichlorophene/toluene) Worming Capsules, NADA 101-498...

2010-08-27

362

Comparison of blood toluene levels after inhalation and oral administration  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this investigation was to compare blood toluene levels in Sprague-Dawley rats after oral and inhalation administration. Groups of 30 rats were dosed by gavage with 86.7, 217, 433, or 867 mg toluene/kg body wt or exposed for up to 6 hr, 5 rats per exposure, to an atmosphere of either 200 or 1000 ppm toluene. Blood was sampled by cardiac puncture from 5 rats in each of the six dose groups at 0.5, 1.0, 2.0, 4.0, 6.0, and 24.0 hr after gavage dosing or the beginning of the inhalation exposure. Blood toluene levels were analyzed. A four-parameter model was fitted to the blood toluene levels of the orally dosed rats. The area under the curve generated by this model, representing total blood toluene concentration over 6 hr, was calculated and compared to the area under the blood toluene curve for the 6-hr inhalation exposure. Integrated areas from the two routes of exposure were used for direct comparison of oral and inhalation exposures. The data demonstrate that gavage dosing can be used to approximate inhalation exposure to toluene.

Sullivan, M.J.; Conolly, R.B.

1988-02-01

363

Active efflux of toluene in a solvent-resistant bacterium.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigated the mechanisms behind the organic-solvent resistance of the solvent-tolerant strain Pseudomonas putida S12. By use of 14C-labeled toluene, we obtained evidence that an energy-dependent export system may be responsible for this resistance to toluene.

Isken, S.; Bont, J. A.

1996-01-01

364

BEHAVIOR OF TOLUENE ADDED TO SLUDGE-AMENDED SOILS  

Science.gov (United States)

Toluene is a priority pollutant that can be introduced to soils in a variety of wastes, including some municipal sludges. aboratory experiments were conducted to study the behavior of toluene in two soils in the presence and absence of municipal sludge. ludge additions increased ...

365

CARDIOVASCULAR AND THERMOREGULATORY RESPONSE TO ORAL TOLUENE IN THE RAT.  

Science.gov (United States)

Toluene and other volatile organic compounds have often been shown to affect behavior in animals when given by inhalation, and less effective when given orally. Previous work showed that toluene increased heart rate (HR) and motor activity (MA), and reduced core temperature (Tc) ...

366

Low benzene content gasoline producing process  

Energy Technology Data Exchange (ETDEWEB)

A process is claimed for the production of a gasoline having a low benzene content. A catalytic reformate and a stripped liquid produced in the gas concentration unit of an fcc unit are fractionated in a dehexanizer to concentrate the benzene and C3-C4 olefins these two streams contain into a single stream. This stream is passed into an alkylation zone wherein at least some of the benzene is alkylated with the olefins. The alkylation zone effluent is stripped and recombined with C7-plus dehexanizer bottoms stream to form a gasoline product stream.

Herout, R.C.; Uitti, K.D.

1980-06-24

367

Enhanced visible-light induced degradation of benzene on Mg-ferrite/hematite/PANI nanospheres: In situ FTIR investigation  

International Nuclear Information System (INIS)

Graphical abstract: The dramatic enhanced visible-light photocatalytic activity of Mg-ferrite/hematite nanospheres photocatalyst on benzene were obtained after hybridized by polyaniline (PANI) using the chemisorption method. 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 CO2 is produced as the final product during the reaction process. Highlights: ? Mg-ferrite/hematite/PANI photocatalysts showed enhanced photocatalytic activity. ? Ethyl acetate, carboxylic acid and aldehyde were the intermediate products. ? CO2 was produced as the final product during the reaction process. ? The high efficiency of charge separation was mainly ascribed to the hybrid effect. - Abstract: 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 CO2 is determined as the final product during the reaction process.

2012-11-30

368

Sensitive detection of a novel class of toluene-degrading denitrifiers, Azoarcus tolulyticus, with small-subunit rRNA primers and probes.  

Science.gov (United States)

Azoarcus tolulyticus is a new class of widely distributed toluene-degrading denitrifiers of potential importance in remediating benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated environments. To detect these organisms in the environment, 16S rRNA gene-based phylogenetic probes were developed. Two sets of specific PCR amplification primers and two oligonucleotide hybridization probes were designed and tested against both closely and distantly related environmental isolates. All of these primers and probes were specific to the species A. tolulyticus. The sensitivity of the PCR amplification primer sets was evaluated with DNA isolated from A. tolulyticus Tol-4 pure culture and from sterile soils seeded with a known number of Tol-4 and Escherichia coli cells. These primer sets were able to detect 1 fg to 1 pg of template DNA from the pure culture and 1.11 x 10(2) to 1.1 x 10(8) Tol-4 cells per g of soil in the presence of 1.56 x 10(10) E. coli cells. These two PCR amplification primers were also successfully tested at two field sites. The primers identified the A. tolulyticus strains among the toluene-degrading bacteria isolated from a low-O2-high-NO(3)- aquifer at Moffett Field, Calif. Also, the presence of A. tolulyticus was detected in the groundwater samples from a BTEX-contaminated aquifer at an industrial site in Detroit, Mich., which showed anaerobic toluene degradation. PMID:9172359

Zhou, J; Palumbo, A V; Tiedje, J M

1997-06-01

369

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.

Cuiqin Wu

2006-12-01

370

Ethyl 2-(5-bromo-3-ethylsulfinyl-1-benzofuran-2-ylacetate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C14H15BrO4S, was prepared by the oxidation of ethyl 2-(5-bromo-3-ethylsulfanyl-1-benzofuran-2-ylacetate with 3-chloroperoxybenzoic acid. The crystal structure is stabilized by aromatic ?–? interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.814?(9?Å], and possibly by weak C—H...? interactions. In addition, the crystal structure exhibits three intermolecular C—H...O non-classical hydrogen bonds. The ethyl group bonded to carboxylate O atom is disordered over two positions, with refined site-occupancy factors of 0.686?(18 and 0.314?(18.

Hong Dae Choi

2009-04-01

371

1-Ethyl-2-phenyl-3-[2-(trimethylsilylethynyl]-1H-indole  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C21H23NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with trimethylsilylacetylene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244?(15?Å] and is oriented at a dihedral angle of 51.48?(4° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C—H...? interactions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the trimethylsilyl unit are equally disordered over two sets of sites.

Iaroslav Baglai

2013-06-01

372

Rearrangements of toluene and cycloheptatriene cations  

International Nuclear Information System (INIS)

The losses of CH3 and CH6 from the gaseous toluene cation (1) were studied using seven isotopic isomers of I and two of cycloheptatriene (2) utilizing high resolution (1: 500000) measurement of the abundance of the isobaric ionic products. Four distinct isomerization pathways, competitive with other I reactions, can be identified: (i) scrambling of the ring hydrogen atoms without involvement of the methyl group; (ii) isomerization I reversible 2 possibly through norcaradiene (7) as an intermediate; (iii) single exchange of an ?-H and ring-H, possibly through methylenecyclohexadiene (8) as an intermediate; and (iv) complete scrambling of carbon as well as hydrogen atoms, possibly through opening of the aromatic ring. Reaction ii appears to involve the tightest activated complex, and i and ii the lowest activation energy; iii is intermediate, while iv has the loosest activated complex and highest activation energy. An additional pathway for the isomerization of 2, possibly through bis(methylene)cyclopentene, is also indicated. (auth)

1975-10-15

373

EPR study of Gallium atoms in benzene  

Energy Technology Data Exchange (ETDEWEB)

An EPR study of a Ga atom matrix isolated in benzene at 77 K has revealed the presence of a paramagnetic species with the magnetic parameters {alpha}{sub zz}(69) = 256 MHz, {alpha}{sub xx}(69) = 270 MHz, {alpha}{sub yy}(69) = 284 MHz, {alpha}{sub zz}(71) = 325 MHz, {alpha}{sub xx}(71) = 343 MHz, {alpha}{sub yy}(71) = 361 Mhz, g{sub zz} = 1.9970, g{approximately}{sub xx} = 1.9750, and g{sub yy} = 1.9350. These parameters are consistent with a trapped atom or a weak Ga-benzene complex that has had the degeneracy of the Ga p orbitals lifted by interaction with the benzene matrix. This contrasts with Al in benzene which gives a mononuclear monoligand complex, Al(C{sub 6}H{sub 6}), with quite strong bonding between the metal atom and the ligand.

Howard, J.A.; Joly, H.A.; Mile, B.; Sutcliffe, R. (National Research Council of Canada, Ottawa, Ontario (Canada))

1991-09-05

374

Recommended sublimation pressure and enthalpy of benzene  

International Nuclear Information System (INIS)

Highlights: • Sublimation pressures of benzene were measured. • Benzene thermodynamic properties in the state of ideal gas were calculated. • Recommended sublimation pressure and enthalpy of benzene were developed. -- Abstract: Recommended vapor pressures of solid benzene (CAS Registry Number: 71-43-2) which are consistent with thermodynamically related crystalline and ideal-gas heat capacities as well as with properties of the liquid phase at the triple point temperature (vapor pressure, enthalpy of vaporization) were established. The recommended data were developed by a multi-property simultaneous correlation of vapor pressures and related thermal data. Vapor pressures measured in this work using the static method in the temperature range from 233 K to 260 K, covering pressure range from 99 Pa to 1230 Pa, were included in the simultaneous correlation. The enthalpy of sublimation was established with uncertainty significantly lower than the previously recommended values

2014-01-01

375

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...subsequent to discharge from bulk terminals and other exemptions specified...Media: Carbon dioxide, dry chemical, or foam. ...benzene concentration in bulk material samples was also...Laboratory Method No. 12 for Bulk Samples Analyte:...

2010-07-01

376

Potassium 2-iodo-benzene-sulfonate monohydrate.  

Science.gov (United States)

In the crystal structure of the title compound, K(+)·C(6)H(4)IO(3)S(-)·H(2)O, the potasium cation is 2.693?(3)-2.933?(3)?Å from the sulfonate and water O atoms (including symmetry-related atoms) and forms a two-dimensional sheet-like structure in the bc plane, with the iodo-benzene rings protruding above and below. The water mol-ecule of crystallization is hydrogen-bonded to sulfonate O atoms within this two-dimensional arrangement. Symmetry-related iodo-benzene rings are arranged perpendicular to one another with the I atom ca 4.1?Å from the centroid of the neighbouring benzene ring. In the crystal structure, these two-dimensional sheet-like supramolecular structures are arranged parallel to one another, stacked along the a-axis direction, with the benzene rings inter-digitated. PMID:21203089

Arshad, Muhammad Nadeem; Khan, Islam Ullah; Ahmad, Saeed; Shafiq, Muhammad; Stoeckli-Evans, Helen

2008-01-01

377

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the sample or clarifying with a clarification kit. 3. Apparatus. 3.1. Liquid chromatograph equipped with a UV detector. 3.2. HPLC Column that will separate benzene from other components in the bulk sample being analyzed. The...

2010-07-01

378

Adsorption of toluene and toluene–water vapor mixture on almond shell based activated carbons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of work is to study the adsorption of a common volatile organic compound such as toluene using activated carbons prepared by chemical activation with phosphoric acid of a lignocellulosic precursor, almond shell, under different conditions. The Impregnation ratio, temperature and time of activation were modified to obtain activated carbons with different characteristics. Regarding the characteristics of the activated carbons, the effects of porous structure and surface chemistry on the...

Marti?nez Yuso, A.; Izquierdo Pantoja, Mari?a Teresa; Rubio Villa, Begon?a; Carrot, P. J. M.

2013-01-01

379

Aromaticity of benzene in condensed phases. A case of a benzene-water system  

Science.gov (United States)

A theoretical Density Functional Theory study was performed for a benzene molecule in water cages. Two DFT functionals (B3LYP and BLYP) were employed. The optimized geometries of the studied clusters were used to calculate the aromaticity of benzene in a condensed phase using the aromaticity indices: HOMA, NICS, PDI, and H. The results were compared with aromaticity of a single benzene molecule in the gas phase and in the solvent environment provided by the PCM continuum model. It is argued that high aromaticity of benzene in the gas phase is retained in the water environment.

Zborowski, Krzysztof K.

2014-05-01

380

Morpholine-4-carboxamidinium ethyl carbonate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The asymmetric unit of the title salt, C5H12N3O+·C3H5O3?, contains two carboxamidinium and two ethyl carbonate ions. In the crystal, the C—N bond lengths in the central CN3 units of the cations range between 1.324?(2) and 1.352?(2)?Å, indicating partial double-bond character. The central C atoms are bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charges are delocalized in the CN3 planes. The morpholine ring...

Ioannis Tiritiris

2012-01-01

 
 
 
 
381

Preliminary response of a pristine aquifer when facing toluene contamination  

Science.gov (United States)

Toluene is a common groundwater contaminant due to the wide spread of gasoline and industrial solvents. The understanding of how and when ecosystems initially respond to the presence of toluene is yet limited, because field investigations rarely start before a contamination has occurred. In order to investigate for the first time such a scenario, a pristine indoor aquifer model (0.8 - 0.7 - 5 m) was constructed, filled with natural sediment, flushed with natural groundwater at a rate of 9 L/hr, and subsequently exposed to a toluene contamination. Investigation was done to the chemical and biological parameters of the model, including oxygen concentration (9.6 mg/L), nitrate concentration (5.8 mg/L), small organic carbon content (0.8 mg/L), microbial abundance (4 x 104 cell/mL), and ATP (0.01 nM). This agreed with the condition of a typical pristine and oligotrophic aquifer. A 30-hr aqueous toluene pulse (water saturated with toluene) was injected into the system together with a conservative tracer (90% D2O). Water samples were collected 4.2 m away from the injection source. The comparison between the toluene and D2O breakthrough curves indicated that a portion of toluene was removed by degradation at a pseudo 1st order rate of 0.017/hr. Stable carbon isotope values of toluene were also measured along with the breakthrough curves. ?13C values were more positive than the original input, confirming that biodegradation had taken place. Subsequent to the pulse, a constant injection of aqueous toluene together with bromide was applied to obtain a deeper insight of the biological and geochemical processes in the aquifer. High resolution water sampling over the entire aquifer model was conducted 80 hrs after the start of constant injection. Microbial abundance and living biomass (ATP) were observed to be 10 - and 100 -, respectively, higher than under pristine conditions. Biodegradation was detected by comparing the concentration of toluene and bromide, and was confirmed by a significant depletion of oxygen concentrations in the center of the plume. Subsequent sediment sampling revealed a pronounced decrease in bacterial diversity and evenness in the toluene plume, indicating fast establishment of the degraders and disappearance of sensitive members. Changes of microbial community composition were accompanied by a build up of biomass and high bacterial carbon production rates. Our study shows that microbial degradation of toluene occurs immediately (within 50 hrs) after exposure of the pristine aquifer to the contaminant. Changes in biological and geochemical processes give additional evidences that the system responds very fast towards toluene contamination and has a high potential for natural attenuation.

Qiu, S.; Herzyk, A.; Maloszewski, P.; Larentis, M.; Griebler, C.; Elsner, M.

2012-04-01

382

Oegonirriterande Egenskaper hos Tio Organiska Aemnen (Eye Irritating Properties of Ten Organic Substances).  

Science.gov (United States)

The acute eye irritating properties of ethyl benzene, isopropanol, isophorone, isobutanol, triethanolamine, 2-ethylhyxyl acrylate, cyclohexanol, morpholine, toluene and hexylamine were examined according to 'OECD Guidelines for Testing of Chemicals, No 40...

B. Koch H. Marchner S. A. Persson

1985-01-01

383

Molecular dynamics study of benzene-benzene and benzene-potassium ion interactions using polarizable potential models  

Energy Technology Data Exchange (ETDEWEB)

We have constructed a polarizable potential model for benzene using molecular dynamics techniques. The atomic site polarizabilities for carbon and hydrogen were taken from the recent work of Applequist [J. Phys. Chem. 97, 6016 (1993)], which reproduced the experimental molecular polarizability of the benzene molecule very accurately. Our model describes well the available experimental data such as the structure and thermodynamic properties of liquid benzene and the equilibrium properties of the liquid/vapor interface of benzene. The lowest minimum-energy structure of the benzene dimer predicted by our model has a T-shape with a potential energy of -2.5 kcal/mol. This value agrees with the experimentally obtained value (-2.4{+-}0.4 kcal/mol), which was determined from a high-precision ionization measurement. The cyclic minimum-energy structures are found for both the benzene trimer and tetramer clusters. The computed density profile shows that the interface is not sharp at a microscopic level and has a thickness about 5 Aa at 300 K. The calculated surface tension is 25{+-}2 dyn/cm, which is in excellent agreement with the experimentally obtained value of 28 dyn/cm. The results of our model also compare well with the corresponding results for benzene obtained by Jorgensen and Severance [J. Am. Chem. Soc. 112, 4768 (1990)], who used nonpolarizable potential parameters. We also report the details of our study of K{sup +}(C{sub 6}H{sub 6}){sub n=1-6} clusters. We found that the polarization effects were quite significant in these systems. (c) 2000 American Institute of Physics.

Dang, Liem X. [P. O. Box 999 Mail Stop K8-91, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2000-07-01

384

Molecular dynamics study of benzene-benzene and benzene-potassium ion interactions using polarizable potential models  

International Nuclear Information System (INIS)

We have constructed a polarizable potential model for benzene using molecular dynamics techniques. The atomic site polarizabilities for carbon and hydrogen were taken from the recent work of Applequist [J. Phys. Chem. 97, 6016 (1993)], which reproduced the experimental molecular polarizability of the benzene molecule very accurately. Our model describes well the available experimental data such as the structure and thermodynamic properties of liquid benzene and the equilibrium properties of the liquid/vapor interface of benzene. The lowest minimum-energy structure of the benzene dimer predicted by our model has a T-shape with a potential energy of -2.5 kcal/mol. This value agrees with the experimentally obtained value (-2.4±0.4 kcal/mol), which was determined from a high-precision ionization measurement. The cyclic minimum-energy structures are found for both the benzene trimer and tetramer clusters. The computed density profile shows that the interface is not sharp at a microscopic level and has a thickness about 5 Aa at 300 K. The calculated surface tension is 25±2 dyn/cm, which is in excellent agreement with the experimentally obtained value of 28 dyn/cm. The results of our model also compare well with the corresponding results for benzene obtained by Jorgensen and Severance [J. Am. Chem. Soc. 112, 4768 (1990)], who used nonpolarizable potential parameters. We also report the details of our study of K+(C6H6)n=1-6 clusters. We found that the polarization effects were quite significant in these systems. (c) 2000 American Institute of Physics

2000-07-01

385

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

386

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

2009-01-01

387

Radiolysis of Aqueous Benzene Solutions  

International Nuclear Information System (INIS)

Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co ?-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

1964-01-01

388

Morpholine-4-carboxamidinium ethyl carbonate  

Directory of Open Access Journals (Sweden)

Full Text Available The asymmetric unit of the title salt, C5H12N3O+·C3H5O3?, contains two carboxamidinium and two ethyl carbonate ions. In the crystal, the C—N bond lengths in the central CN3 units of the cations range between 1.324?(2 and 1.352?(2?Å, indicating partial double-bond character. The central C atoms are bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charges are delocalized in the CN3 planes. The morpholine rings are in chair conformations. The C—O bond lengths in both ethyl carbonate ions are characteristic for delocalized double bonds [1.243?(2–1.251?(2?Å] and typical single bonds [1.368?(2 and 1.375?(2?Å]. In the crystal, N—H...O hydrogen bonds between cations and anions generate a two-dimensional network in the ac plane.

Ioannis Tiritiris

2012-12-01

389

Acute cardiotoxic effects of high dose toluene: an experimental study  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: This study aimed to investigate the acute cardiotoxic effects of high dose toluene and its damage mechanisms on heart tissue in the acute period.Methods: Twenty adult male Wistar Albino rats (200-220 g were used in this controlled experimental animal study. Animals were divided into two equal groups: a control group (Group 1 and a high dose (6 mL/kg/gavage toluene-administered group (Group 2. Arterial blood pressure (BP and heart rate (HR values were measured at 30th, 60th and 90th minutes after toluene was administered. At the end of the experimental period, blood samples and heart tissues were taken from the rats. Serum troponin T levels were assayed. Heart tissue sections were stained using routine histological methods and examined under a light microscope. In addition, the sections were immunohistochemically stained using the avidin-biotin-peroxidase method to determine caspase-3 immunoreactivity and TUNEL to detect apoptosis. To compare the apoptotic index, the Mann-Whitney U test was used. For comparisons between the two groups, the independent t- test was used. In addition, time-based changes of intra-group parameters were evaluated using paired t tests. Results: BP and HR values were low in toluene-treated rats compared to the control group. Troponin T levels were increased in toluene-administered animals as compared with controls [Toluene group: 0.140 (0.010-2.000 ng/mL vs control group: 0.010 (0.010-0.010 ng/mL, p=0.01]. Histopathologic examination of heart tissue sections showed congestion and edema in toluene administrated rats. Higher TUNEL positivity and (+++ immunoreactivity for caspase-3 protein were observed in the toluene group compared to the control group. Conclusion: The present study demonstrated that high doses of toluene cause apoptosis and may lead to impairment of cardiac function in the acute period.

Ufuk Ta?

2013-03-01

390

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

391

Acute behavioural comparisons of toluene and ethanol in human subjects.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A comparison of toluene and ethanol (EtOH) induced changes in central nervous system (CNS) function and symptoms were evaluated in two studies, and when possible the effects of toluene were expressed in EtOH equivalent units. The toluene concentrations were 0, 75, and 150 ppm, bracketing the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) of 100 ppm. The socially relevant EtOH doses were 0.00, 0.33, and 0.66 g EtOH/kg body weight, equivalent to two ...

1991-01-01

392

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.

2010-06-01

393

Multi-scale simulation on solid benzene  

Science.gov (United States)

Solid Benzene is used in organic semiconductors for photovoltaics, which often include pi-conjugated systems. We use MD simulations method to explore the relationship between the structure and interaction energy of two kinds of solid benzene, with the Pbca and P21c crystallgraphic structures respectively. Simple relevant force fields (PCFF and CVFF) are examined with regard to their performance on the structure and energetics of benzene dimers and benzene crystals which serve as well characterized model systems. However, MD simulations cannot get the transport properties. So the combination of reliable classical atomistic simulations and quantum-mechanical methods is needed to understand the dynamics of charge transport and self-assembly processes involving pi-conjugated oligomers and polymers. As alternative and accurate models, we explore atomistic models with additional sites which represent the location of the pi electrons and are characterized by suitable charges and van-der-Waals parameters. With these parameters, it will be possible to reproduce the dimer geometries and energies, the crystal structure of solid benzene, as well as pi-stacking forces and free energies for similar systems.

Liu, Hua; Heinz, Hendrik

2009-03-01

394

Benzene monitoring at CPPI service stations  

International Nuclear Information System (INIS)

A study was conducted in which ambient airborne concentration levels of benzene were measured at a representative set of gasoline service stations in Toronto and Vancouver. Benzene is considered to be toxic under the Canadian Environmental Protection Act (CEPA). It is a component in gasoline (0.1 to 4.7 per cent by volume) and is present in vehicle evaporative and exhaust emissions. Measurements were made every 18 days at each station for one year. The objective of the study was to assess the ambient and employee exposure levels of benzene at service stations and to determine whether the levels were typical of those published in the literature. In a 1986 PACE (Petroleum Association for Conservation of the Canadian Environment) survey of exposure to gasoline hydrocarbon vapours at Canadian service stations, airborne benzene concentration data was inconsistent with similar ambient and personal exposure data in the international literature. It was concluded that both the mean ambient benzene concentration and the personal exposure level measurements in this study were generally lower than similar measurements made in other countries. The same observation was made with respect to ambient and personal exposure levels measured in this study vis-a-vis those measured during the PACE study conducted in 1985/86. . 31 refs., 24 tabs., 5 figs

1996-03-01

395

Psychomotor performance and subjective symptoms at low level toluene exposure  

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Objectives: Possible effects of long term occupational exposure to toluene below the level of 100 ppm on psychomotor performance and subjective symptoms were investigated in a cross sectional approach.

Zupanic, M.; Demes, P.; Seeber, A.

2002-01-01

396

Conducting Polymer Electrochemically Generated Via Anodic Oxidation of Toluene.  

Science.gov (United States)

As opposed to the much harsher conditions demanded in homogeneous solutions, a conducting polymer of toluene is readily formed by anodic oxidation of acetonitrile solutions containing the precursor. The fabrication of new conductive polymers is of interes...

D. B. Parry J. M. Harris K. Ashley S. Pons

1988-01-01

397

Extraction-spectrophotometric determination of boron with 4,6-di-tert-butyl-3-methoxycatechol and ethyl violet  

Energy Technology Data Exchange (ETDEWEB)

4,6-Di-tert-butyl-3-methoxycatechol (DBMC) has been developed as a new reagent for boron, the complex anion formed being extracted as an ion-associate with Ethyl Violet into toluene, and the absorbance measured at 610 nm. The calibration graph is linear up to 0.43 ..mu..g of boron, the molar absorptivity is 1.02 x 10/sup 5/ 1.mole/sup -1/.cm/sup -1/ and the relative standard deviation 1.2%. The method has been applied to the determination of boron in sea-water and river water with satisfactory results. (author).

Oshima, Mitsuko; Shibata, Kiyomi; Gyouten, Takako; Motomizu, Shoji; Toei, Kyoji

1988-05-01

398

Extraction-spectrophotometric determination of boron with 4,6-di-tert-butyl-3-methoxycatechol and ethyl violet  

International Nuclear Information System (INIS)

4,6-Di-tert-butyl-3-methoxycatechol (DBMC) has been developed as a new reagent for boron, the complex anion formed being extracted as an ion-associate with Ethyl Violet into toluene, and the absorbance measured at 610 nm. The calibration graph is linear up to 0.43 ?g of boron, the molar absorptivity is 1.02 x 105 1.mole-1.cm-1 and the relative standard deviation 1.2%. The method has been applied to the determination of boron in sea-water and river water with satisfactory results. (author)

1988-01-01

399

Piperidine-1-carboxamidinium ethyl carbonate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title salt, C6H14N3+·C3H5O3?, the C—N bond lengths in the central CN3 unit of the carboxamidinium cation are 1.3262?(18, 1.3359?(18 and 1.3498?(18?Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3 plane. The piperidine ring is in a chair conformation. The C—O bond lengths in the ethyl carbonate anion are characteristic for a delocalized double bond and a typical single bond. In the crystal, N—H...O hydrogen bonds between cations and anions generate a two-dimensional network in the direction of the ab plane, whereas adjacent ion pairs form chains running along the b axis.

Ioannis Tiritiris

2012-12-01

400

Rheology of asphaltene-toluene/water interfaces.  

Science.gov (United States)

The stability of water-in-crude oil emulsions is frequently attributed to a rigid asphaltene film at the water/oil interface. The rheological properties of these films and their relationship to emulsion stability are ill defined. In this study, the interfacial tension, elastic modulus, and viscous modulus were measured using a drop shape analyzer for model oils consisting of asphaltenes dissolved in toluene for concentrations varying from 0.002 to 20 kg/m(3). The effects of oscillation frequency, asphaltene concentration, and interface aging time were examined. The films exhibited viscoelastic behavior. The total modulus increased as the interface aged at all asphaltene concentrations. An attempt was made to model the rheology for the full range of asphaltene concentration. The instantaneous elasticity was modeled with a surface equation of state (SEOS), and the elastic and viscous moduli, with the Lucassen-van den Tempel (LVDT) model. It was found that only the early-time data could be modeled using the SEOS-LVDT approach; that is, the instantaneous, elastic, and viscous moduli of interfaces aged for at most 10 minutes. At longer interface aging times, the SEOS-LVDT approach was invalid, likely because of irreversible adsorption of asphaltenes on the interface and the formation of a network structure. PMID:16316096

Sztukowski, Danuta M; Yarranton, Harvey W

2005-12-01

 
 
 
 
401

Polypropylene-based composites reinforced by toluene diisocyanate modified wood  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Composites made of polypropylene, a mixture of polypropylene and poly(lactic acid) and spruce wood fibres both non-modified and modified with toluene 2,4-diisocyanate - were prepared by melt blending. The chemical modifications of wood fibres with toluene 2,4-diisocyanate were evidenced by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Wood fibre reinforced polypropylene/poly(lactic acid) composites prepared with addition of maleic anhydride polypropylene as cou...

2013-01-01

402

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

Science.gov (United States)

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. PMID:23688693

Filley, Christopher M

2013-06-01

403

Vapor–Liquid Equilibrium in Diluted Polymer + Toluene Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vapor–liquid equilibrium data were determined for five polymer plus toluene systems at isothermal conditions between 60 and 100 oC. Polymers comprise copolymers and terpolymers of octadecyl acrylate, acrylic acid, styrene, and 1-vinyl-2-pyrrolidone because of their practical importance as flow improvers for crude oil and/or derivatives. All-glass micro-ebulliometer with circulation of liquid phase was used for measurement of total pressure over polymer + toluene mixtures. Two predictive g...

2011-01-01

404

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

405

[Exposure to benzene of service station employees and composition of benzene].  

Science.gov (United States)

The International Agency for Research on Cancer (IARC) classifies gasoline vapours and exhaust fumes from gasoline fueled automobiles as potential human carcinogens. Data on the chemical composition of gasoline marketed in Italy and especially on the concentration of benzene, are rather poor. Within the framework of an investigation aimed at assessing the mean annual level of exposure to aromatic hydrocarbons among gasoline pump attendants, made on a sample of attendants in Rome between December 1991 and November 1992, samples of gasoline were also collected so as to determine the benzene content of the gasoline over the investigation period, assess the variability of benzene concentration in the various gasolines and according to the season of the year, and take account of gasoline composition in analysing the factors determining individual exposure levels of pump attendants. Benzene exposure was measured via gas chromatography of air samples obtained with personal pumps in the breathing zone. The mean benzene exposure level (8 h TWA) of the 27 subjects under study was 1.73 mg/m3 (SD = 5.53). The benzene concentration in the samples of gasoline, which were collected on the same day as personal exposure monitoring was performed, was measured by means of high resolution gas chromatography (hr-GC). Mean benzene levels of 25.03 g/l (SD = 3.47), equivalent to 2.86% by volume, were measured in 24 samples of alkylated gasoline, and mean levels of 23.18 g/l (SD = 3.93), equivalent to 2.65% v/v, were measured in 10 samples of lead-free gasoline. Statistically significant associations were found between individual exposure to benzene and the quantity of gasoline pumped (r = 0.69) and the quantity of benzene present in the gasoline sold on the day monitoring was performed (r = 0.70). Using regression analysis, the estimated increase in the level of personal benzene exposure was 0.01 mg/m3 for every increase of 100 g in the benzene content of the total amount of gasoline sold. This estimation could be used to quantify the expected reduction in benzene exposure levels in service station attendants following a reduction in the benzene content of gasoline. PMID:7885296

Lagorio, S; Fuselli, S; Iavarone, I; Vanacore, N; Carere, A

1994-01-01

406

Hepatic metabolism of toluene after gastrointestinal uptake in humans  

DEFF Research Database (Denmark)

The metabolism of toluene and the influence of small doses of ethanol were measured in eight male volunteers after gastrointestinal uptake, the toluene concentration in alveolar air and the urinary excretion of hippuric acid and ortho-cresol being used as the measures of metabolism. During toluene exposure to 2 mg.min-1 for 3 h the alveolar toluene concentration was 0.07 (range 0-0.11) mg.m-3; exposure to 6 mg.min-1 for 30 min increased the alveolar concentration to 0.9 (range 0.03-2.6) mg.m-3. Ingestion of 0.08, 0.16, and 0.32 g of ethanol per kilogram of body weight during toluene exposure of 2 mg.min-1 increased the alveolar concentration within 10 min, and maximal alveolar concentrations of 5 (SD 3), 24 (SD 11), and 39 (SD 28) mg.m-3 were reached after 30, 60, and 90 min for the three doses, respectively. Hippuric acid excretion was only decreased by an ethanol dose of 0.32 g.kg-1. Very low doses of ethanol inhibit toluene metabolism, and the procedure is sensitive enough to measure metabolic interactionsbetween solvents and other xenobiotics in humans.

Bælum, Jesper; Mølhave, Lars

1993-01-01

407

Semicontinuous microcosm study of aerobic cometabolism of trichloroethylene using toluene  

International Nuclear Information System (INIS)

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-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

2007-09-30

408

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.

2003-01-01

409

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

410

Determination of Toluene's degradation products under simulated atmospheric conditions  

Science.gov (United States)

The toluene oxidation process was studied by blacklight irradiation of 1-10ppm each of toluene and oxides of nitrogen in 22-liter pyrex flasks, in zero-air at 50% relative humidity. The products were recovered from the walls by extraction with methanol or dichloromethane. Some gas-phase products were recovered in the solvent as well. The extracts were analyzed on a Finnigan MAT triple stage quadrupole mass spectrometer/data system by direct probe injection. Once their molecular weights were determined, the products were fragmented by collision-dissociation (CID) in the middle quadrupole to produce characteristic daughter ions. To assist in the spectral interpretation, toluene in three isomeric forms was subjected to simulated atmospheric reaction. In addition to normal (H8) toluene, methyl-deuterated (D3) and per-deuterated (D8) toluene were used. This study confirmed the existence of a number of products identified in past studies, confirmed the formation of some products which have been hypothesized in several proposed mechanisms for toluene oxidation, identified a number of previously unidentified and unproposed products.

Dumdei, B. E.

1984-12-01

411

Development of a hybrid fermentation-enzymatic bioprocess for the production of ethyl lactate from dairy waste.  

Science.gov (United States)

This work explores the potential for the development of a hybrid fermentation-enzymatic process for the production of ethyl lactate from dairy waste. Cheese whey was used in Kluyveromyces marxianus and Lactobacillus bulgaricus batch cultures to produce ethanol and lactic acid respectively. Subsequently, the fermentation products were transferred into an organic phase through liquid-liquid extraction and ethyl lactate was formed in an esterification reaction catalyzed by lipases. The production of ethanol and lactic acid achieved under different conditions was 23gL(-1) and 29gL(-1), respectively. Furthermore, the efficiency of various organic solvents for the esterification reaction was evaluated and toluene was chosen for application in the process. The effect of water content was determined aiming to maximize the product yield and 40mgml(-1) was the optimal enzyme concentration. The bioprocess achieved maximum conversion of 33% constituting a valuable alternative to the application of energy demanding chemically derived methods. PMID:24785788

Koutinas, Michalis; Menelaou, Maria; Nicolaou, Evrydiki N

2014-08-01

412

Stable Hydrogen and Carbon Isotope Fractionation during Microbial Toluene Degradation: Mechanistic and Environmental Aspects†  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Primary features of hydrogen and carbon isotope fractionation during toluene degradation were studied to evaluate if analysis of isotope signatures can be used as a tool to monitor biodegradation in contaminated aquifers. D/H hydrogen isotope fractionation during microbial degradation of toluene was measured by gas chromatography. Per-deuterated toluene-d8 and nonlabeled toluene were supplied in equal amounts as growth substrates, and kinetic isotope fractionation was calculated from the shif...

Morasch, Barbara; Richnow, Hans H.; Schink, Bernhard; Meckenstock, Rainer U.

2001-01-01

413

Effects of ethanol and phenobarbital treatments on the pharmacokinetics of toluene in rats.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rats were exposed to toluene at a wide range of concentrations from 50 to 4000 ppm for six hours, and the effects of ethanol and phenobarbital (PB) treatments on the pharmacokinetics of toluene metabolism were investigated. Ethanol treatment influenced toluene metabolism mainly at low exposure concentrations. Thus ethanol accelerated the clearance of toluene from blood only when the blood concentration of toluene was not high (less than 360 microM), and ethanol increased hippuric acid (HA) ex