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Biodegradation characteristics of naphthalene and benzene, toluene, ethyl benzene, and xylene (BTEX) by bacteria enriched from activated sludge.  

Science.gov (United States)

Naphthalene and BTEX (benzene, toluene, ethyl benzene, and xylene) are frequently detected toxic hydrocarbons in contaminated sites, which can easily enter the soil or groundwater system. To test the potential of treating these hydrocarbons in a conventional water resource recovery facility, municipal activated sludge was used as the seed and the bacteria successfully enriched using naphthalene or BTEX as the sole carbon source under aerobic conditions. The pseudo first order kinetic constant for naphthalene degradation by enriched bacteria was 14.053 L h(-1) g(-1). For BTEX degradation, kinetic constants of 0.234, 0.958, 1.212, and 0.455 L h(-1) g(-1)1' were obtained for benzene, toluene, ethyl benzene, and xylene, respectively, which collectively accounted for a total BTEX removal rate constant of 0.550 L h(-1) g(-1) . Through cloning and sequencing, Pseudomonas and Burkholderia were identified as the primary bacteria communities in the naphthalene degradation reactor, whereas for BTEX degradation, Pseudomonas and Acidovorax dominated in the reactor. PMID:24734475

Huang, Yuanxing; Li, Liang

2014-03-01

2

Benzene, toluene, ethyl benzene and xylenes in ambient air and Pinus sylvestris L. needles: a comparative study between Belgium, Hungary and Latvia  

Science.gov (United States)

Concentrations of benzene, toluene, ethyl benzene and xylenes (BTEX) in ambient air and in 1 yr old Pinus sylvestris pine needles were monitored along a busy road, petrol station and rural area of Belgium, Hungary and Latvia in a 1 yr period. To test P. sylvestris as a possible biomonitor for the BTEX concentrations, samples were taken in the four seasons. As the distribution of data was not normal, the level of pollution on different sites and seasons was compared and evaluated by non-parametric tests. The measured air concentrations did not differ significantly from one season to another throughout the year. There were, however, differences between sampling places. The C 2-alkylbenzene and toluene concentrations in the needles were similar in the autumn/winter and spring/summer periods but a significant decrease in their concentration was observed in every place between winter and spring. This effect was less obvious for toluene.

Keymeulen, Regine; Görgényi, Miklós; Héberger, Károly; Priksane, Anda; Van Langenhove, Herman

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

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

K. L. Shivabasappa

2008-03-01

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

Scientific Electronic Library Online (English)

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

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

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Diaquabis(L-phenylalaninato)nickel(II) encapsulated in zeolite: an efficient heterogeneous catalyst system for the oxidation of cyclohexene, toluene and ethyl benzene  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese L-Fenilalanina reage com zeólita Y submetida a uma troca iônica com níquel(II) para formar diaquabis(L-fenilalaninato)níquel(II), o qual é encapsulado nos poros da zeólita. Nesta forma encapsulada, o complexo de níquel funciona como um catalisador eficiente quando ciclo-hexeno, tolueno e etilbenzeno [...] são oxidados por peróxido de hidrogênio na presença de bicarbonato de sódio como cocatalisador. O catalisador foi facilmente recuperado da mistura de reação e foi reutilizado por três vezes sem perda observável de atividade. O catalisador heterogêneo apresentou atividade e seletividade significativamente mais altas quando comparado com o complexo diaquabis(L-fenilalaninato)níquel(II). Abstract in english L-Phenylalanine reacts with nickel-exchanged zeolite Y to form diaquabis(L-phenylalaninato)nickel(II), which is encapsulated in the pores of the zeolite. In this zeolite-encapsulated form, the nickel derivative functions as an efficient catalyst when cyclohexene, toluene and ethyl benzene are oxidiz [...] ed by hydrogen peroxide in the presence of sodium bicarbonate (as co-catalyst). The catalyst was readily recovered from the reaction mixture, and it could be re-used for other three runs without noticeable loss of activity. The heterogeneous catalyst exhibited significantly higher activity and selectivity compared with diaquabis(L-phenylalaninato)nickel(II) itself.

Massomeh, Ghorbanloo; Somayeh, Ghamari; Nahid, Shahbakhsh; Seik Weng, Ng.

2073-20-01

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The thermal conductivity of benzene and toluene  

Science.gov (United States)

The thermal conductivity of liquid toluene and benzene was measured in the temperature range 298 to 370 K, near the saturation line, using an absolute transient hot-wire technique. The measurements were made in a modified version of an existing instrument, equipped with a new automatic Wheatstone bridge, computer controlled. The bridge measures the time that the resistance of a 7- ?m-diameter platinum wire takes to reach predetermined values, programmed by the computer. The computer can generate up to 1024 analog voltages, via a 12-bit D/A converter. The accuracy of the measurements with this new arrangement was assessed by measuring the thermal conductivity of a primary standard, toluene, at several temperatures and was found to be of the order of 0.3%. Benzene was chosen because it is under study as a possible secondary standard for liquid thermal conductivity by the Subcommittee on Transport Properties of IUPAC.

Ramires, M. L. V.; Vieira Dos Santos, F. J.; Mardolcar, U. V.; de Castro, C. A. Nieto

1989-09-01

7

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

Science.gov (United States)

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 ?g/L and 500 ?g/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. PMID:24857895

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

2014-06-30

8

Thermophilic biofiltration of benzene and toluene.  

Science.gov (United States)

In the current studies, we characterized the degradation of a hot mixture of benzene and toluene (BT) gases by a thermophilic biofilter using polyurethane as packing material and high-temperature compost as a microbial source. We also examined the effect of supplementing the biofilter with yeast extract (YE). We found that YE substantially enhanced microbial activity in the thermophilic biofilter. The degrading activity of the biofilter supplied with YE was stable during long-term operation (approximately 100 d) without accumulating excess biomass. The maximum elimination capacity (1,650 g x m(-3) h(-1)) in the biofilter supplemented with YE was 3.5 times higher than that in the biofilter without YE (470 g g x m(-3) h(-1)). At similar retention times, the capacity to eliminate BT for the YE-supplemented biofilter was higher than for previously reported mesophilic biofilters. Thus, thermophilic biofiltration can be used to degrade hydrophobic compounds such as a BT mixture. Finally, 16S rDNA polymerase chain reaction-DGGE (PCR-DGGE) fingerprinting revealed that the thermophilic bacteria in the biofilter included Rubrobacter sp. and Mycobacterium sp. PMID:18167445

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

2007-12-01

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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 (60Co, 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

10

Diffusive Motions in Benzene and Toluene Studied with Slow Neutrons  

International Nuclear Information System (INIS)

The viscosity of benzene is described by the Arrhenius equation ? = const. exp (E/kBT), where E is the activation energy for viscous flow. The viscosity of toluene, however, follows this law only in the higher temperature region of its liquid range, i.e. above the Arrhenius temperature TA. In the whole normal liquid range the benzene molecule is supposed to be able to rotate many times about at least two symmetry axes between translational jumps. Davies and Matheson suggest that the onset of non-Arrhenius viscosity behaviour in toluene occurs at that temperature at which rotation about two axes becomes restricted, while rotation about the third remains free. Inelastic scattering experiments of slow neutrons have been performed on the two substances using a time-of-flight spectrometer for cold neutrons with an energy resolution of 12 %. The quasi-elastic scattering has been studied for small momentum transfer as a function of temperature. Diffusion coefficients have been determined assuming a Lorentzian cross-section. The temperature dependence of the diffusion coefficient for benzene follows an exponential law, but the coefficient is a few times larger than the macroscopic coefficient, showing that a large amount of rotational diffusion exists. For toluene there is a change in the temperature dependence of the coefficient at about TA. This is taken as an indication of a change in the number of degrees of rotational freedom of the toludegrees of rotational freedom of the toluene molecule around TA. The methyl group in toluene has a low barrier to rotation (?500 cal/mole). Therefore the hindered rotation levels of the methyl group as well as molecular rotation will contribute significantly to the inelastic scattering spectrum which overlaps the quasi-elastic peak. Th e inelastic component is subtracted by extrapolation but the possible contribution of the CH3 rotation to the quasi-elastic peak itself is neglected. (author)

11

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

Science.gov (United States)

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

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

12

Methyl-substitution of benzene and toluene in preparations of human bone marrow  

Energy Technology Data Exchange (ETDEWEB)

The metabolism of benzene and toluene was investigated in preparations of human bone marrow incubated with S-adenosyl-L-methionine. Benzene undergoes a methyl-substitution reaction to yield toluene as a metabolite. Furthermore, toluene undergoes methyl-substitution in preparations of human bone marrow incubated with S-adenosyl-L-methionine to yield o-xylene, m-xylene, and p-xylene. Metabolites were detected by gas chromatography and mass spectroscopy. No metabolism of either benzene or toluene was detected when a boiled bone marrow preparation was used in the incubation, demonstrating the enzymatic nature of the S-adenosyl-L-methionine dependent methylation of both benzene and toluene.

Flesher, J.W.; Myers, S.R. (Univ. of Kentucky, Lexington (USA))

1991-01-01

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Anti-benzene compounds. Conversion of benzene to toluene by methyl donors, in man.  

Science.gov (United States)

The level of benzene in blood can be efficiently reduced, an its noxious effect neutralized, by the concurrent administration of either of two groups of organic compounds: 1) methyl donors such as choline and betaine; and, 2) cysteine-HCL. Methionine acts as a precursor of cysteine in the body as uell as a methyl donor like choline and betaine. The appearance of toluene in blood was demonstrated after the sequential ingestion of choline plus betaine, benzene. The results are discussed in relation to clinical application in workers chronically exposed to benzene. PMID:594433

Braier, L

1977-01-01

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Enhanced Anaerobic Biodegradation of Benzene-Toluene-Ethylbenzene-Xylene-Ethanol Mixtures in Bioaugmented Aquifer Columns  

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Methanogenic flowthrough aquifer columns were used to investigate the potential of bioaugmentation to enhance anaerobic benzene-toluene-ethylbenzene-xylene (BTEX) degradation in groundwater contaminated with ethanol-blended gasoline. Two different methanogenic consortia (enriched with benzene or toluene and o-xylene) were used as inocula. Toluene was the only hydrocarbon degraded within 3 years in columns that were not bioaugmented, although anaerobic toluene degradation was observed after on...

Da Silva, Marcio L. B.; Alvarez, Pedro J. J.

2004-01-01

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A comparison of benzene, toluene and C 2-benzenes mixing ratios in automotive exhaust and in the suburban atmosphere during the introduction of catalytic converter technology to the Swiss Car Fleet  

Science.gov (United States)

Time-resolved chemical ionization mass spectrometry (CIMS) has been used to investigate the variations of the mixing ratios of benzene, toluene and the C 2-benzenes (xylenes and ethyl benzene) in automotive exhaust during transient engine operation. A significant increase of the benzene/toluene ratios from 0.35 to 1.31 (median) was found upon introduction of a catalytic converter system. A preliminary emission model was developed from these test stand measurements to simulate benzene/toluene ratios of passenger car fleets with variable proportions of three-way catalyst vehicles. Although only the emissions of gasoline-driven passenger cars have been considered so far, the predicted increase of the benzene/toluene ratios during the introduction period of the three-way catalyst from 1980 to 2000 is in good agreement with the observed increase of the atmospheric benzene/toluene ratio measured at a suburban monitoring site (Dübendorf, Switzerland) which is strongly influenced by road traffic emissions. At this site, the atmospheric concentrations of benzene and alkyl benzenes have been detected at hourly intervals since 1993. A steady decrease of the yearly mean from 3.54 to 2.00 ppb for toluene and from 2.87 to 1.33 ppb for the sum of C 2-benzenes was found from 1994 to 1998, respectively, when the proportion of three-way catalyst passenger cars increased from 60 to 82%. Nevertheless, the mean benzene concentration was only affected to a small degree (from 1.10 to 0.97 ppb) within the same period of time. Thus, the observed increase of the atmospheric benzene/toluene-mixing ratios from 0.32 to 0.58 (mean) is in good agreement with the predicted values from the presented emission model. Reduced catalyst conversion efficiency for benzene with respect to alkylated benzenes can explain most of the observed increase of the benzene/toluene and benzene/C 2-benzenes mixing rations. In addition, benzene emissions e.g. from the class of light duty vehicles, which are operated more frequently at sub-optimal combustion conditions, may also contribute to the unexpectedly stable atmospheric benzene concentration at the investigated suburban monitoring site.

Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian; Reimann, Stefan; Herzog, Alex; Jäckle, Hans W.

16

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

International Nuclear Information System (INIS)

The G-values of H2, CH4 and C2H2 are determined in toluene-benzene and toluene-styrene mixtures. From the results it is concluded that CH3 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 C2H2 which could be hexatrienyl is efficiently scavenged by toluene, presumably by H atom transfer. This reaction also accounts for the very low yield of C2H2 in pure toluene. (author)

17

Modeling Biodegradation Kinetics on Benzene and Toluene and Their Mixture  

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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

18

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

19

Methyl-substitution of benzene and toluene in preparations of human bone marrow.  

Science.gov (United States)

The metabolism of benzene and toluene was investigated in preparations of human bone marrow incubated with S-adenosyl-L-methionine. Benzene undergoes a methyl-substitution reaction to yield toluene as a metabolite. Furthermore, toluene undergoes methyl-substitution in preparations of human bone marrow incubated with S-adenosyl-L-methionine to yield o-xylene, m-xylene, and p-xylene. Metabolites were detected by gas chromatography and mass spectroscopy. No metabolism of either benzene or toluene was detected when a boiled bone marrow preparation was used in the incubation, demonstrating the enzymatic nature of the S-adenosyl-L-methionine dependent methylation of both benzene and toluene. PMID:1994190

Flesher, J W; Myers, S R

1991-01-01

20

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

 
 
 
 
21

In vitro metabolism of benzene, toluene, and xylene in rat liver  

International Nuclear Information System (INIS)

A headspace gas chromatographic method was used to study the metabolism of benzene, toluene, and m-xylene in rat liver. Metabolism of benzene was lower than that of toluene, or m-xylene. Investigating metabolic rates of subcellular fractions, it was found that glutathione and glutathione S-transferase in the cytosol are involved in metabolism of benzene and toluene by microsomes. When both benzene and toluene are present in the incubation medium, they act as inhibitors of each others metabolism. Toluene and m-xylene metabolism were induced by the pretreatment of rats with phenobarbital (75 mg/kg), or 3-methylcholanthrene (25 mg/kg), or Aroclor 1254 (75 mg/kg) for 3 days, whereas benzene metabolism was not induced by all pretreatments. Another series of experiments was conducted to compare the effects of benzene, toluene, and xylene pretreatment on liver metabolism. In vivo metabolism of 14C-toluene and possible covalent binding of 14C-toluene to microsomes were also investigated. 14C-toluene when incubated with liver microsomes in the presence of a NADPH generating system formed benzylalcohol and cresols. Some of the radioactivity was covalently bound preferentially to microsomal proteins. The binding process required cytochrome P-450 dependent mixed function oxidases. This study suggests that toluene is metabolized to several reactive intermediates by liver microsomal enzymes and these metabolites are responsible for the covalent bindites are responsible for the covalent binding to macromolecules which represents a subcellular mechanism by which toluene may express its own in vivo toxicity

22

Vapor-liquid equilibria for the binary systems of benzene/toluene, diphenylmethane/toluene, m-cresol/1,2,3,4-tetrahydronaphthalene, and quinoline/benzene  

Energy Technology Data Exchange (ETDEWEB)

Vapor-liquid equilibrium (VLE) data for the binary systems of benzene/toluene, diphenylmethane/toluene, m-cresol/1,2,3,4-tetrahydronaphthalene, and benzene/quinoline were measured at low to moderate pressures (0-1733 kPa) by using a static equilibrium cell. The data were isothermally correlated by using the Peng-Robinson equation of state to describe both vapor and liquid phases. The data were also correlated by using the Peng-Robinson equation of state to describe the vapor phase and the universal quasi-chemical (UNIQUAC) excess Gibbs free energy expression for the liquid phase.

Klara, S.M.; Mohamed, R.S.; Dempsey, D.M.; Holder, G.D.

1987-04-01

23

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

24

Mixture effects during the oxidation of toluene, ethyl acetate and ethanol over a cryptomelane catalyst.  

Science.gov (United States)

The catalytic oxidation of two-component VOC mixtures (ethanol, ethyl acetate and toluene) was studied over cryptomelane. Remarkable mixture effects were observed on the activity and the selectivity. Toluene inhibits both ethyl acetate and ethanol oxidation, this effect being more evident in the case of ethyl acetate. For instance, the temperature for 100% conversion is about 210 °C when ethyl acetate is oxidised alone, and 250 °C or higher, when it is oxidised in mixtures with toluene. On the contrary, toluene oxidation is only slightly inhibited by the presence of ethyl acetate, while the presence of ethanol has a promoting effect. Concerning the mixtures of ethyl acetate and ethanol, both compounds have a mutual inhibitory effect, which is more evident in the case of ethyl acetate (the temperature for 100% conversion of ethyl acetate is about 45 °C higher when ethyl acetate is oxidised in mixtures with ethanol, while in the case of ethanol the corresponding increase is only 10 °C). PMID:21044815

Santos, V P; Pereira, M F R; Órfão, J J M; Figueiredo, J L

2011-01-30

25

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.

26

Dermal exposure assessment to benzene and toluene using charcoal cloth pads.  

Science.gov (United States)

Charcoal cloth pads have been used to assess volatile chemicals on the skin in a laboratory setting; however, they have not yet been applied to measure dermal exposure in occupational settings. This study aimed at evaluating whether charcoal pads can be used to assess dermal exposure to benzene and toluene in workers of a petrochemical plant. Inhalation and dermal exposure levels to benzene and toluene were assessed for workers of a petrochemical plant performing different jobs. Benzene uptake was assessed by determining S-phenylmercapturic acid in workers' urine samples. Dermal exposure levels on the charcoal pads were adjusted for ambient air levels of benzene and toluene by subtracting the amount of benzene or toluene measured in personal air from the amount of benzene or toluene measured on the charcoal pad. In general, measured external and internal exposure levels were low. The estimated contribution of the dermal route to internal benzene exposure levels was less than 0.06% for all jobs. Toluene personal air concentrations and benzene and toluene dermal exposure levels differed statistically significantly between job titles. For benzene, differences between jobs were larger for adjusted dermal exposures (maximum 17-fold, P = 0.02) than for inhalation exposures (maximum two-fold, P = 0.08). Also for toluene, although less clear, differences between jobs were larger for adjusted dermal exposures (maximum 23-fold, P = 0.01) as compared to inhalation exposures (maximum 10-fold, P = 0.01). Charcoal pads appeared to measure dermal exposures to benzene and toluene in addition to ambient air levels. Future studies applying charcoal cloth pads for the dermal exposure assessment at workplaces with higher dermal exposure to organic solvents may provide more insight into the biological relevance of dermal exposure levels measured by charcoal cloth pads. In addition, the design of the dermal sampler might be improved by configuring a dermal sampler, where part of the sampler is protected against direct contact and splashes, but still permeable for the gas phase. This design would most likely result in a better ability to correct for airborne concentrations at a given body location. PMID:15083162

van Wendel de Joode, Berna; Tielemans, Erik; Vermeulen, Roel; Wegh, Hillion; Kromhout, Hans

2005-01-01

27

Monomer and dimer radical cations of benzene, toluene, and naphthalene.  

Science.gov (United States)

Pulse radiolytic generation of monomeric and dimeric cations of benzene, toluene, and naphthalene in aqueous acid media at room temperature and their spectrophotometric characterization is discussed. Results presented include measurements of each aromatic's solubility in H(2)O-H(2)SO(4) and H(2)O-HClO(4) media over the acidity range pH 1 to H(0) -7.0, facile oxidative generation, and real-time identification of appropriate cationic transients with respective lambda(max) (nm) and epsilon (M(-1) cm(-1)) values measured as follows: C(6)H(6)(*+) (443, 1145 +/- 75), C(6)H(5)CH(3)(*+) (428, 1230 +/- 90), C(10)H(8)(*+) (381, 3650 +/- 225, and 687, 2210 +/- 160), (C(6)H(6))(2)(*+) (860, 2835 +/- 235), (C(6)H(5)CH(3))(2)(*+) (950, 1685 +/- 155), and (C(10)H(8))(2)(*+) (1040, 4170 +/- 320). Kinetic measurements reveal the respective formation rates of monomeric cations to be near-diffusion controlled, while the forward rate values for the dimeric species generation are marginally slower. The proton activity corrected pK(a) values are found to remain between -2.6 and -1.3 for the ArH(*+) species (C(6)H(6)(*+) most acidic, C(10)H(8)(*+) least acidic), while the pK(a) values of (ArH)(2)(*+) species vary from -5.0 to -3.0 ((C(6)H(6))(2)(*+) most acidic, (C(10)H(8))(2)(*+) least acidic). In H(0) -5 in aqueous H(2)SO(4), the respective stabilization energy of (C(6)H(6))(2)(*+), (C(6)H(5)CH(3))(2)(*+), and (C(10)H(8))(2)(*+) is estimated to be 16.6, 15.0, and 13.7 kcal mol(-1). Thus, the aqueous acid solution emerges as an alternative medium for typical radical-cationic studies, while offering compatibility for the deprotonated radical characterization near neutral pH. PMID:19453117

Das, Tomi Nath

2009-06-11

28

Dynamics of Ethyl Benzene Synthesis Using Aspen Dynamics  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of the study is to generate a plant wide control strategy using Aspen Dynamics for synthesis of Ethyl Benzene process which consists of two CSTRs in series followed by two distillation columns. Steady state simulation has been carried out prior to dynamic simulation using Aspen Plus and exported to Aspen dynamics after providing the required sizing details under flow driven mode. In addition to default controllers, five more controllers are added and the necessary specifications regarding process variable, output variable and set point are specified for each controller. One cascade controller, two ratio controllers, two pressure controllers, four temperature controllers and six level controllers are used in the present study. Controllers are tuned by using Tyreus-Luyben and Ziegler-Nichols controller settings. The response of the whole process is studied for various step disturbances to find the optimal controller parameters and control structure.

A. Sarath Babu, Babasheb Londhe

2014-07-01

29

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 18O-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% 18O label after incubation in 9% 18O-labeled medium. Gas chromatography-mass spectrometry was used to detect the 18O-labeled aromatic metabolites

30

Solubilities of Toluene, Benzene and TCE in High-Biomass Systems  

Energy Technology Data Exchange (ETDEWEB)

We report measurements of solubility limits for benzene, toluene, and TCE in systems that contain varying levels of biomass up to 0.13 g/mL. The solubility limit increased from 20 to 48 mM when biomass (in the form of yeast) was added to aqueous batch systems containing benzene. The toluene solubility limit increased from 4.9 to greater than 20 mM. For TCE, the solubility increased from 8 mM to more than 1000 mM. Solubility for TCE was most heavily impacted by biomass levels, changing by two orders of magnitude.

Barton, John W. [Battelle Eastern Science & Technology Center; Vodraska, Christopher D [ORNL; Flanary, Sandie A. [Oak Ridge National Laboratory (ORNL); Davison, Brian H [ORNL

2008-01-01

31

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

32

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 SF6 as diluent gases. To help elucidate the variations in reaction mechanism with temperature, we also studied OH reactions with deuterated benzene (C6D6) and with selectively deuterated toluenes (C6H5CD3, C6D5CD3, and C6D5CH3). 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 achievedfor toluene is achieved

33

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, aberrationdicentric + 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

34

Combined effects of simultaneous ?-rays irradiation and inhalation of benzene, toluene and carbon monoxide on rabbits  

International Nuclear Information System (INIS)

Combined effects on rabbits induced by ?-rays irradiation in combination with inhalation of benzene, toluene and carbon monoxide and the interactive characteristics (antagonistic, additive or synergistic) of these agents were studied. Ninety healthy male rabbits were equally divided into 9 groups, eight of which were test groups assigned according to four factor- two-dose-level orthogonal layout [L8(27)] program and one was the control. The two dose-levels of the four factors were: for ?-rays irradiation, 0.0075 Gy/d and 0.0375 Gy/d, and for benzene, toluene and carbon monoxide, 40 +- 15 mg/m3 and 182 +- 33 mg/m3, 90 +- 30 mg/m3 and 407 +- 68 mg/m3, 93 +- 4 mg/m3 and 278 +- 8 mg/m3 respectively. The animals were exposed to ?-rays irradiation combined with benzene, toluene and CO vapor 2h a day and 5 days a week for a period of 8 weeks. Experimental results were analysed with the method of variance analysis and the test groups were compared. The results showed that (1) the interactive factor, the ratio (?) of the combined effects caused by the four agents to the sum of the four independent effects induced by those agents, was 2.16, 1.58, 2.07, 2.67, 1.31 and 1.18 for dicentric + ring, acentric, aberration cells, total aberration, micronuclei and SCEs/C in lymphocytes respectively, and the ratio for aberrant sperms was as high as 5.97. The ratios showed that interactions were maitios showed that interactions were mainly synergistic (? > 1). However, for acentric interactions between ?-rays and benzene was antagonistic. (2) The four agents could all obviously cause decrease in testis weight index, and ?-rays, benzene and CO could markedly reduce the number of sperms and increase the ratio of aberrant sperms. The interactions between ?-rays and benzene for the decrease in testis weight index and for the elevation of the ratio of aberrant sperms were synergistic. (3) CO could cause decrease in total amount of leucocytes, thrombocytes and hemoglobin, and toluene cause decrease in lymphocytes. (4) Gamma rays irradiation combined with inhalation of benzene, toluene and CO could produce significant interactions which were mainly synergistic, and CO, when combined with ?-rays, benzene and toluene, could cause obvious effects on gland

35

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.)

36

The impact of reduction in the benzene limit value in gasoline on airborne benzene, toluene and xylenes levels.  

Science.gov (United States)

Background benzene, toluene, xylenes (BTX) average concentrations have been measured over the urban agglomeration of Toulouse, France, during both springtime and summer periods of 1999 and 2001. The benzene average amount over the two Toulouse campaigns in 1999 is equal to 2.2 microg/m(3), very close to the French air quality standard and well under the average value of 5 microg/m(3) recommended by European Economic Community countries, recognising that those regulations are given for a whole year. BTX pollution over Toulouse has, in particular, been produced by motor vehicle exhaust gases. For the study conducted during the same periods of 2001, benzene concentrations were within the French quality value in the whole area. This is because the benzene limit value contained in gasoline went from 5% to 1% since 2000 January 1. It will 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. PMID:15504504

Simon, V; Baer, M; Torres, L; Olivier, S; Meybeck, M; Della Massa, J P

2004-12-01

37

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

International Nuclear Information System (INIS)

(>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water site remedial with a mobile Electron Beam facility. (Author)

38

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

International Nuclear Information System (INIS)

It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO2 and H2O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author

39

Hybrid Separation and Detection Device for Analysis of Benzene, Toluene, Ethylbenzene, and Xylenes in Complex Samples  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements tog...

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

2009-01-01

40

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Degradation of the BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes) group of organopollutants by the white-rot fungus Phanerochaete chrysosporium was studied. Our results show that the organism efficiently degrades all the BTEX components when these compounds are added either individually or as a composite mixture. Degradation was favored under nonligninolytic culture conditions in malt extract medium, in which extracellular lignin peroxidases (LIPs) and manganese-dependent pe...

Yadav, J. S.; Reddy, C. A.

1993-01-01

 
 
 
 
41

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

Science.gov (United States)

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.

Ng, N. L.; Kroll, J. H.; Chan, A. W. H.; Chhabra, P. S.; Flagan, R. C.; Seinfeld, J. H.

2007-07-01

42

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

International Nuclear Information System (INIS)

The structures of benzene (C6H6, C6D6) and toluene (C6H5-CH3, C6D5-CD3) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10-4 cm2/s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

43

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 1000C; no H-D exchange occurred between C6H6 and C6D6 up to 1000C. Up to 1000C, benzene was displaced as C6H6(g) by P(CH3)3. Benzene reversible thermal desorption occurred at 115 to 1250C, accompanied by extensive irreversible decomposition to H2(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(CH3)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 1000C higher than that for Ni(111). H-D exchange did not occur with D2 + C6H6 and with C6H6 + C6D6 on Ni(100). Toluene chemisorption on all the nickel surfaces was thermally irreversible and toluene was not displaced from these surfaces by strong fieisplaced from these surfaces by strong field ligands like P(CH3)3 and CH3NC. Heating the Ni-toluene surfaces led to hydrogen evolution. For the decomposition of C6D5CD3 on Ni(111) there were two D2 thermal desorption maxima, 130 and 1900C. For the analogous decomposition of C6H5CD3 and C6D5CH3 respectively, there were single D2 desorption curves with maxima at 130 and 1850C, respectively. Thus, aliphatic C-H bonds are broken first and no aromatic C-H bond is broken until near 1600C. Identical behavior was observed for the stepped and stepped-kinked surfaces, and an analogous behavior was observed for the (100) surface

44

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

International Nuclear Information System (INIS)

Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO2, SO2, O3, benzene, and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO2 concentrations were anti-correlated to the O3 concentrations, is expected. SO2 also showed a pronounced dependence on car traffic. Average benzene and toluene concentrations were, respectively 1.7 ppb and between 4.4 and 6.6 pbb, but high values of toluene up to 98.8 ppb were observed. SO2 concentrations and to a lesser extent, those of NO2 and O3, were dependent on the wind direction. Ozone in Brussels has been found to be influenced by the meteorological conditions prevailing in central Europe. Comparisons with other measurements have shown that O3 and SO2 data are in general in good agreement, but our NO2 concentrations seem to be generally higher. (author)

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Biodegradation of benzene, toluene, ethylbenzene, and o-xylene by the bacterium Mycobacterium cosmeticum byf-4.  

Science.gov (United States)

A new strain Mycobacterium cosmeticum byf-4 able to simultaneously degrade benzene, toluene, ethylbenzene, and o-xylene (BTE(o-)X) compounds has been isolated and identified previously in our laboratory. We further report here the extent of degradation of every BTE(o-)X component, and unravel the initial mechanism involved in BTE(o-)X degradation. This organism efficiently degrades all the BTE(o-)X components when these compounds are added either individually or as a composite mixture, and has a preference for toluene followed by benzene, ethylbenzene and then o-xylene. The significantly high carbon recovery indicated that the predominant fate for BTE(o-)X compounds was mineralization and incorporation into cell materials. The presence of BTE compounds in binary or ternary mixtures consistently had a negative effect on o-xylene degradation. The initial steps involved in the degradation of BTE(o-)X were investigated by isolation of metabolites and assay of reverse transcription RT-PCR. Isolation of metabolites suggested that the BTE(o-)X compounds were initially converted by a dioxygenase to their respective catechols. The gene sequence of the PCR amplicons revealed that this isolate contained a 454-bp toluene dioxygenase (TOD) fragment. The BTE(o-)X-specific induction of the genes encoding TOD was confirmed by RT-PCR analysis. These results indicated that TOD was possibly responsible for the initial steps of BTE(o-)X catabolism in M. cosmeticum byf-4. PMID:22960059

Zhang, Lili; Zhang, Chao; Cheng, Zhuowei; Yao, Yanlai; Chen, Jianmeng

2013-01-01

46

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

47

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.

48

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

49

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

50

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

51

Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenze, 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

52

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-12-23

53

Assessment of Toluene/Biphenyl Dioxygenase Gene Diversity in Benzene-Polluted Soils: Links between Benzene Biodegradation and Genes Similar to Those Encoding Isopropylbenzene Dioxygenases†  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The PCR-single-strand conformation polymorphism (SSCP) technique was used to assess the diversity and distribution of Rieske nonheme iron oxygenases of the toluene/biphenyl subfamily in soil DNA and bacterial isolates recovered from sites contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX). The central cores of genes encoding the catalytic ? subunits were targeted, since they are responsible for the substrate specificities of these enzymes. SSCP functional genotype fingerpri...

Witzig, Robert; Junca, Howard; Hecht, Hans-ju?rgen; Pieper, Dietmar H.

2006-01-01

54

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

Science.gov (United States)

Concentrations of benzene, toluene, C2-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4-10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism. PMID:7785357

Biedermann, M; Grob, K; Morchio, G

1995-04-01

55

Degradation of Eu(fod)3 electronic excitation energy in benzene, toluene, and o-xylene solutions  

International Nuclear Information System (INIS)

Ways of energy dissipation resulting from Eu(fod)3 electronic excitation in homological series of solvents-benzene, toluene and o-xylene have been studied. It is ascertained that probability of the electronic excitation energy degradation increases with an increase in the number of methyl groups at aromatic ring. The values of the activation energy of Eu(fod)3 chelate excited state quenching, which correlate with the number of methyl groups in the series benzene (35.6±1.3 kJ/mol), toluene (39.3±1.3 kJ/mol), o-xylene (54.4±0.8 kJ/mol), have been determined. The results obtained suggest that the main contribution to Eu(3+) electronic excitation energy degradation in homological series benzene, toluene, o-xylene is made by nonradiating energy transfer to high-frequency overtones of oscillations in the solvent C-H groups

56

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

57

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-07-12

58

Subclinical effects of groundwater contaminants. Pt. 3. Effects of repeated oral exposure to combinations of benzene and toluene on immunologic responses in mice  

Energy Technology Data Exchange (ETDEWEB)

Toxicity of environmental pollutants may be expressed as combined effects of chemicals. Benzene, a proven hematotoxic agent, frequently occurs with toluene in cocontaminated groundwater. Groups of CD-1 male mice were exposed continuously for 4 weeks to benzene (166 mg/l), toluene (80 and 325 mg/l), and combinations of benzene (166 mg/l) + toluene (80 mg/l or 325 mg/l) in drinking water. Benzene-induced anemia was alleviated by simultaneous toluene treatment. Leukopenia and lymphopenia were observed in the case of benzene only and benzene + toluene (80 mg/l)-treated mice. The cytopenia, however, was less severe in the benzen + toluene (325 mg/l)-treated group. Immunotoxicity induced by benzene treatment alone was characterized by involution of thymic mass and suppressions of both B- and T-cell mitogeneses, mixed lymphocyte culture response to alloantigens, the tumor lytic ability of cytotoxic T-lymphocytes as determined by {sup 51}Cr-release assay, and antibody production response to T-dependent antigen (sheep red blood cells). IL-2 secretion by Con A-stimulated mouse T-cells was decreased in the benzene-treated group. Toluene (325 mg/l) completely inhibited these adverse effects when it was coadministered with benzene, while the low dose of toluene (80 mg/l) did not protect against benzene-induced depressions of immune functions. Toluene administered alone at levels up to 325 mg/l showed no abvious immunotoxic effects. Results of this study demonstrated that toluene, in sufficient amounts, has an antagonistic effect on benzene immunotoxicity. (orig.).

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

1990-06-01

59

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)

60

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

 
 
 
 
61

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

International Nuclear Information System (INIS)

xposed simultaneously to test chemical along with quercetin or curcumin. The study further suggests the suitability of D. melanogaster as an alternate animal model for toxicological studies involving benzene, toluene and xylene and its potential in studying the protective role(s) of phytochemicals.

62

Heats of adsorption of benzene and toluene vapors on polyhydroxyaluminum montmorillonite  

Science.gov (United States)

Changes that occur in the surface properties and porous structure of montmorillonite when sodium ions are replaced with polyhydroxyaluminum ions are studied. It is established that thermal evacuation significantly affects the adsorption and energy properties of polyhydroxyaluminum montmorillonite (PHAM). The dependences of the differential isosteric heats of adsorption and desorption on the amount of adsorbed substance are determined from data on a series of isosteres for the sorption of benzene and toluene on dehydrated PHAMs, where the curves of the heats of sorption of C6H6 and C7H8 are of an extreme character. It is concluded that the occurrence of maxima is determined by the interaction between molecules of adsorbates and active centers (and with one another) due to packing upon the filling of the volumes of slittype micropores.

Muminov, S. Z.; Khandamov, D. A.; Agzamkhodzhaev, A. A.

2014-09-01

63

Separation of benzene, toluene, ethylbenzene, and xylenes by micellar electrokinetic capillary chromatography.  

Science.gov (United States)

The use of sodium dodecyl sulfate, urea, beta-cyclodextrin, and methanol as additives to the electrophoretic medium containing a Na2HPO4-boric acid buffer in the micellar electrokinetic capillary chromatography of benzene, toluene, ethylbenzene, and three isomers of xylene (collectively known as BTEX) was investigated. The results showed that with the addition of sodium dodecyl sulfate only, higher selectivity and sensitivity and shorter migration time could be achieved, which consequently resulted in better separation of BTEX studied. For this buffer system, good linearity (R2>0.99) was found over the range of 5 to 500 microg ml(-1) for individual BTEX compound and separation time of less than 5 min for BTEX was possible. PMID:15027649

Shim, H; Hwang, B; Yang, S T

2004-01-01

64

Genetic effects of thinner, benzene and toluene in Drosophila melanogaster. 2. Sex linked recessive lethal, mutations and translocations II-III  

Directory of Open Access Journals (Sweden)

Full Text Available The effects of thinner, benzene and toluene on the;induction of sex-linked recessive lethal mutations and translocations 11-111 in D~osophila melanogaster were investigated by means of a genetic scheme designed. by Oster and a modified z for statistical analysis. Thinner induced sex-linked recessive lethals while benzene and toluene did not. Translocations 11-111 were produced only by benzene.

Rosario Rodr\\u00EDguez Arnaiz

1985-01-01

65

Optimization of Solid Phase Micro-Extraction (SPME for Monitoring Occupational Exposure to Ethyl Benzene  

Directory of Open Access Journals (Sweden)

Full Text Available AbstractBackground and Objectives: Analytical methods for volatile organic compounds (VOCs in different samples need extraction of compounds, by applying hazardous solvents. Solid phase micro-extraction (SPME is a solvent-free equilibrium extraction method, in which proper calibration can allow quantitative determinations of VOCs at a very good sensitivity without the use of any organic solvent. VOCs are generally present in urine only at trace levels, therefore, a sensitive procedure is needed for their trace determinations. Throughout this study, headspace solid phase micro-extraction (HS-SPME was followed by GC-FID for ethyl benzene in spiked urine was optimized.Methods: In this study, the parameters influencing SPME and gas chromatography of ethyl benzene, including extraction time, temperature, desorption temperature, desorption time, salt addition, sample pH, sample volume and sample agitation were investigated. Results: Extraction procedure was performed at 30°C for 6 min, using 0.2 gml-1 of NaCl in the sample solution. The sample volume and sample pH were optimized at 5 ml and 7 (neutral pH, respectively. Desorption of the ethyl benzene was carried out for 60 sec. at 250°C. The method was also validated with three different spiked urine samples and illustrated an appropriate reproducibility over six consecutive days as well as six within-day experiments. During this investigation, parameters of accuracy, linearity, and detection limits of the procedure were also evaluated.Conclusion: The developed method of HS- SPME-GC-FID proved to be a simple, convenient, and practical procedure, and was successfully used for measuring of ethyl benzene in spiked urine.

H. Heidari

2009-08-01

66

Mobility of supercooled liquid toluene, ethylbenzene, and benzene near their glass transition temperatures investigated using inert gas permeation.  

Science.gov (United States)

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 are 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 to 135 K. In this temperature range, diffusivities are found to vary across 5 orders of magnitude (?10(-14) to 10(-9) cm(2)/s). The diffusivity data are compared to viscosity measurements and reveal a breakdown in the Stokes-Einstein relationship at low temperatures. However, the data are well fit by the fractional Stokes-Einstein equation with an exponent of 0.66. 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. PMID:23758621

May, R Alan; Smith, R Scott; Kay, Bruce D

2013-11-21

67

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 temperature, space-time and the feed ratio of benzene to ethanol on benzene conversion over most acidic zeolite were studied. The kinetic and adsorption constants of the rate equations were estimated by the best fit. From the estimated kinetic constants, the activation energies and frequency factors for various reactions were determined. The activation energy values compared well with those reported by other investigators for same reactions over similar catalysts.

Sanghamitra Barman

2010-01-01

68

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 wal that may result in elimination of the wetland. 70 refs., 20 figs., 14 tabs

69

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 rm 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.

70

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-04-15

71

Risk Assessment of Volatile Organic Compounds Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) in Consumer Products.  

Science.gov (United States)

Exposure and risk assessment was performed by evaluating levels of volatile organic compounds (VOC) benzene, toluene, ethylbenzene, and xylene (BTEX) in 207 consumer products. The products were categorized into 30 different items, consisting of products of different brands. Samples were analyzed for BTEX by headspace-gas chromatography/mass spectrometry (headspace-GC/MS) with limit of detection (LOD) of 1 ppm. BTEX were detected in 59 consumer products from 18 item types. Benzene was detected in whiteout (ranging from not detected [ND] to 3170 ppm), glue (1486 ppm), oil-based ballpoint pens (47 ppm), and permanent (marking) pens (2 ppm). Toluene was detected in a leather cleaning product (6071 ppm), glue (5078 ppm), whiteout (1130 ppm), self-adhesive wallpaper (15-1012 ppm), shoe polish (806 ppm), permanent pen (609 ppm), wig adhesive (372 ppm), tapes (2-360 ppm), oil-based ballpoint pen (201 ppm), duplex wallpaper (12-52 ppm), shoes (27 ppm), and air freshener (13 ppm). High levels of ethylbenzene were detected in permanent pen (ND-345,065 ppm), shoe polish (ND-277,928 ppm), leather cleaner (42,223 ppm), whiteout (ND-2,770 ppm), and glue (ND-792 ppm). Xylene was detected in permanent pen (ND-285,132 ppm), shoe polish (ND-87,298 ppm), leather cleaner (12,266 ppm), glue (ND-3,124 ppm), and whiteout (ND-1,400 ppm). Exposure assessment showed that the exposure to ethylbenzene from permanent pens ranged from 0 to 3.11 mg/kg/d (men) and 0 to 3.75 mg/kg/d (women), while for xylene, the exposure ranges were 0-2.57 mg/kg/d and 0-3.1 mg/kg/d in men and women, respectively. The exposure of women to benzene from whiteout ranged from 0 to 0.00059 mg/kg/d. Hazard index (HI), defined as a ratio of exposure to reference dose (RfD), for ethylbenzene was 31.1 (3.11 mg/kg/d/0.1 mg/kg/d) and for xylene (2.57 mg/kg/d/0.2 mg/kg/d) was 12.85, exceeding 1 for both compounds. Cancer risk for benzene was calculated to be 3.2 × 10(-5) based on (0.00059 mg/kg/d × 0.055 mg/kg-d(-1), cancer potency factor), assuming that 100% of detected levels in some products such as permanent pens and whiteouts were exposed in a worst-case scenario. These data suggest that exposure to VOC via some consumer products exceeded the safe limits and needs to be reduced. PMID:25343298

Lim, Seong Kwang; Shin, Han Seung; Yoon, Kyung Sil; Kwack, Seung Jun; Um, Yoon Mi; Hyeon, Ji Hyeon; Kwak, Hyo Min; Kim, Ji Yun; Kim, Tae Young; Kim, Yeon Joo; Roh, Tae Hyun; Lim, Duck Soo; Shin, Min Kyung; Choi, Seul Min; Kim, Hyung Sik; Lee, Byung-Mu

2014-01-01

72

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

73

Substrate interactions during the biodegradation of benzene, toluene, ethylbenzene, and xylene (BTEX) hydrocarbons by the fungus Cladophialophora sp. strain T1.  

Science.gov (United States)

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 different extents. o-Xylene and m-xylene were converted to phthalates as end metabolites; p-xylene was not degraded in complex BTEX mixtures but, in combination with toluene, appeared to be mineralized. The metabolic profiles and the inhibitory nature of the substrate interactions indicated that toluene, ethylbenzene, and xylene were degraded at the side chain by the same monooxygenase enzyme. Our findings suggest that soil fungi could contribute significantly to bioremediation of BTEX pollution. PMID:12039717

Prenafeta-Boldú, F X; Vervoort, J; Grotenhuis, J T C; Van Groenestijn, J W

2002-06-01

74

Anaerobic Degradation of Benzene, Toluene, Ethylbenzene, and o-Xylene in Sediment-Free Iron-Reducing Enrichment Cultures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX) are widespread contaminants in groundwater. We examined the anaerobic degradation of BTEX compounds with amorphous ferric oxide as electron acceptor. Successful enrichment cultures were obtained for all BTEX substrates both in the presence and absence of AQDS (9,10-anthraquinone-2,6-disulfonic acid). The electron balances showed a complete anaerobic oxidation of the aromatic compounds to CO2. This is the first...

Jahn, Michael K.; Haderlein, Stefan B.; Meckenstock, Rainer U.

2005-01-01

75

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Jurandir Pereira Pinto; Carmen Luísa Barbosa Guedes; Ilza Lobo; Rafael Augusto Melquiades

2006-01-01

76

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

Science.gov (United States)

Biofiltration was used to eliminate volatile organic compounds from air streams in bench-scale reactors inoculated with an adapted consortium. Organic and inert supports were tested on 100 days of operation. The supports were: peat, vermiculite, a mixture of vermiculite and activated carbon, tree bark and, porous glass Rashig rings. A mixture of benzene, toluene and xylene vapors with a load of 200 gC m(-3) h(-1) was fed to the biofilters with an empty bed residence time of 60 s. Removal efficiencies higher than 95% were obtained with the mixture of vermiculite and activated carbon, 85% for peat and bark, 80% for vermiculite and 65% for the Rashig rings. In all cases, drying problems in beds were observed after several days of operation. Water addition with or without nutrients was required to maintain and increase the performance of biofilters. In steady state operation, experiments at loads ranging from 50 to 400 gC m(-3) h(-1) were carried out and a maximum elimination capacity of 260 gC m(-3) h(-1) was obtained for vermiculite-activated carbon support. The three xylene isomers were degraded. Observations of the supports surface by scanning electronic microscopy at the end of the biofiltration experiment showed abundant growth of fungi, which were not in the inoculum, had colonized the biofilter. PMID:12703852

Ortiz, I; Revah, S; Auria, R

2003-03-01

77

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

78

Mixture effects of benzene, toluene, ethylbenzene, and xylenes (BTEX) on lung carcinoma cells via a hanging drop air exposure system.  

Science.gov (United States)

A recently developed hanging drop air exposure system for toxicity studies of volatile chemicals was applied to evaluate the cell viability of lung carcinoma A549 cells after 1 and 24 h of exposure to benzene, toluene, ethylbenzene, and xylenes (BTEX) as individual compounds and as mixtures of four or six components. The cellular chemical concentrations causing 50% reduction of cell viability (EC50) were calculated using a mass balance model and came to 17, 12, 11, 9, 4, and 4 mmol/kg cell dry weight for benzene, toluene, ethylbenzene, m-xylene, o-xylene, and p-xylene, respectively, after 1 h of exposure. The EC50 decreased by a factor of 4 after 24 h of exposure. All mixture effects were best described by the mixture toxicity model of concentration addition, which is valid for chemicals with the same mode of action. Good agreement with the model predictions was found for benzene, toluene, ethylbenzene, and m-xylene at four different representative fixed concentration ratios after 1 h of exposure, but lower agreement with mixture prediction was obtained after 24 h of exposure. A recreated car exhaust mixture, which involved the contribution of the more toxic p-xylene and o-xylene, yielded an acceptable, but lower quality, prediction as well. PMID:24836216

Liu, Faye F; Escher, Beate I; Were, Stephen; Duffy, Lesley; Ng, Jack C

2014-06-16

79

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

80

Actual commuter exposure to methyl-tertiary butyl ether, benzene and toluene while traveling in Korean urban areas  

Energy Technology Data Exchange (ETDEWEB)

This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area.

Lee, Jin-Woo; Jo, Wan-Kuen [Department of Environmental Engineering, Kyungpook National University, 702-701 Taegu (Korea, Republic of)

2002-05-27

 
 
 
 
81

Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature.  

Science.gov (United States)

The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene and acetonitrile. The obtained materials were applied as coatings onto nickel-titanium (Ni-Ti) alloy wires which were incorporated into solid-phase microextraction devices and finally tested for their ability to competitively adsorb vapors from the headspace of an aqueous solution containing a few volatile organic compounds. Porosity analysis showed that, regardless of the solvent used, only a high cross-linking level permitted the preparation of mesoporous copolymers (BJH radius typically in the range 13-15 nm), a requirement for providing accessibility to the targeted nanoscale-imprinted cavities. A noticeable exception was, however, observed for the MMA/DVB copolymers which exhibited much diminished BJH radius. The porosity data correlated well with the extraction profiles found, which suggested the presence of benzene-imprinted sites in all the highly cross-linked copolymers prepared in benzene, except for the MMA/DVB copolymers. Concerning the effect of an elevated conditioning temperature on the memory-effects created by the imprinting process, the results were clearly indicative that the tested copolymers, including the more robust highly cross-linked ones, are not suitable for high temperature applications such as solid-phase microextraction coupled to gas chromatography. PMID:24176503

Azenha, Manuel; Schillinger, Eric; Sanmartin, Esther; Regueiras, M Teresa; Silva, Fernando; Sellergren, Börje

2013-11-13

82

Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK  

Science.gov (United States)

Highly spatially resolved mixing ratios of benzene and toluene, nitrogen oxides (NOx) and ozone (O3) were measured in the atmospheric boundary layer above Greater London during the period 24 June to 9 July 2013 using a Dornier 228 aircraft. Toluene and benzene were determined in-situ using a proton transfer reaction mass spectrometer (PTR-MS), NOx by dual channel NOx chemiluminescence and O3 mixing ratios by UV absorption. Average mixing ratios observed over inner London at 360 ± 10 m a.g.l. were 0.20 ± 0.05, 0.28 ± 0.07, 13.2 ± 8.6, 21.0 ± 7.3 and 34.3 ± 15.2 ppbv for benzene, toluene, NO, NO2 and NOx respectively. Linear regression analysis between NO2, benzene and toluene mixing ratios yielded a trimodal distribution indicating that these compounds predominantly share the same or co-located sources within the city and that a significant fraction of NOx is directly emitted as NO2. Average mixing ratios measured at 360 ± 10 m a.g.l. over outer London were always lower than over inner London. Where traffic densities were highest, the toluene / benzene (T / B) concentration ratios were highest (average of 1.8 ± 0.3 ppbv ppbv-1) indicative of strong local sources. Daytime maxima in NOx, benzene and toluene mixing ratios were observed in the morning (~40 ppbv NOx, ~350 pptv toluene and ~200 pptv benzene) and for ozone in the mid-afternoon (~40 ppbv O3) all at 360 ± 10 m a.g.l.

Shaw, M. D.; Lee, J. D.; Davison, B.; Vaughan, A.; Purvis, R. M.; Lewis, A. C.; Hewitt, C. N.

2014-10-01

83

Theoretical explanation of nonexponential OH decay in reactions with benzene and toluene under pseudo-first-order conditions.  

Science.gov (United States)

OH radical reactions with benzene and toluene have been studied in the 200-600 K temperature range via the CBS-QB3 quantum chemistry method and conventional transition-state theory. Our study takes into account all possible hydrogen abstraction and OH-addition channels, including ipso addition. Reaction rates have been obtained under pseudo-first-order conditions, with aromatic concentrations in large excess compared to OH concentrations, which is the case in the reported experiments as well as in the atmosphere. The reported results are in excellent agreement with the experimental data and reproduce the discontinuity in the Arrhenius plots in the 300 K or = 400 K the reaction occurs exclusively by H abstraction. At 298 K, ipso addition contributes 13.0% to the overall OH + toluene reaction, while the major products correspond to ortho addition, which represents 43% of all possible channels. PMID:18661930

Uc, Víctor Hugo; Alvarez-Idaboy, J Raúl; Galano, Annia; Vivier-Bunge, Annik

2008-08-21

84

A comparative investigation on catalytic oxidation of CO, benzene, and toluene over birnessites derived from different routes  

Science.gov (United States)

Catalytic oxidation of CO, benzene, and toluene was studied over the octahedral layered birnessites (OL-1, OL-2, OL-3, and OL-4) derived from different routes. Physicochemical properties of the samples were characterized by a number of different analytical techniques. It is found that all of the samples have birnessite-type octahedral layered structure and an interlayer spacing of ca. 0.72 nm. Surface areas and pore volumes of the OL-3 and OL-4 samples were much higher than those of the OL-1 and OL-2 samples. There was co-presence of Mn3+, Mn4+ and/or Mn2+ on the surface of these samples. Based on the manganese ion contents, the average oxidation states of surface Mn species in the birnessite samples were in the range of 3.2-3.5, which was lower than those (3.5-3.9) obtained from the H2-TPR studies. The amounts of oxygen vacancies and lattice oxygen mobility of the OL-1 and OL-4 samples were higher than those of the OL-2 and OL-3 samples. Either in CO oxidation or in benzene or toluene oxidation, the catalytic activity decreased in the order of OL-1 > OL-4 >> OL-3 > OL-2, with the OL-1 sample showing the best performance (T50% = 115 and T100% = 150 °C for CO oxidation at 15,000 mL/(g h), T50% = 200 °C and T95% = 240 °C for benzene oxidation, and T50% = 190 °C and T95% = 230 °C for toluene oxidation at 40,000 mL/(g h)). We conclude that catalytic performance of the octahedral layered birnessite samples was associated with the Mn oxide nature, surface lattice oxygen mobility, and reducibility.

Ye, Qing; Lu, Heng; Zhao, Jun; Cheng, Shuiyuan; Kang, Tianfang; Wang, Dao; Dai, Hongxing

2014-10-01

85

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

86

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. T...

Abdulrahman Bahrami; Hosien Mahjub; Marzieh Sadeghian; Farideh Golbabaei

2011-01-01

87

Comparative study of the effects of toluene, benzene, 1,1,1-trichloroethane, diethyl ether, and flurothyl on anxiety and nociception in mice  

International Nuclear Information System (INIS)

The main purpose of this study was to compare the effects of solvents from different chemical classes on anxiety and nociception. Independent groups of mice were exposed to air (control group), toluene (1000-4000 ppm), benzene (1000-4000 ppm), 1,1,1-trichloroethane (TCE, 2000-12000 ppm), diethyl ether (10,000-30,000) or flurothyl (200-600 ppm). After a 30-min exposure, animals were tested either in the anxiety paradigm conditioned defensive burying (CDB) test or in the hot plate test. All solvents but flurothyl produced anxiolytic-like actions being the order of potency toluene > benzene > TCE > diethyl ether. When tested in the hot plate paradigm, toluene and TCE increased nociception, benzene and diethyl ether had no effects, and flurothyl decreased nociception Additional groups of mice were conditioned to recognize the aversive stimulus (electrified prod) prior to toluene exposure and then tested in the CDB test. In unconditioned animals, toluene increased the number of shocks that mice received; however, when mice had previous experience in the CDB test, toluene lacked this effect. Taken together, these results show that inhalants have different effects with different potencies both in the CDB and in the hot plate tests. Additionally, data suggest that acute administration of toluene could impair learning

88

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

International Nuclear Information System (INIS)

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

89

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

International Nuclear Information System (INIS)

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

90

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)

91

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)

92

Characterization of plasma-enhanced teflon AF for sensing benzene, toluene, and xylenes in water with near-IR surface plasmon resonance.  

Science.gov (United States)

Near-IR surface plasmon resonance is used to characterize Teflon AF films for refractive index-based detection of the aromatic hydrocarbon contaminants benzene, toluene, and xylenes in water. The technique requires no sample preparation, and film sensitivity is found to be enhanced by oxygen plasma etching. A diffusion equation model is used to extract the diffusion and partition coefficients, which indicate film enrichment factors exceeding two orders of magnitude, permitting a limit of detection of 183, 105 and 55 ppb for benzene, toluene, and xylenes, respectively. The effect of other potential interfering contaminants is quantified. PMID:24401397

Erickson, Tim A; Nijjar, Rajvir; Kipper, Matt J; Lear, Kevin L

2014-02-01

93

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-05-01

94

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 modificationification

95

IMPACT OF ETHANOL ON THE NATURAL ATTENUATION OF BENZENE, TOLUENE, AND O-XYLENE IN A NORMALLY SULFATE-REDUCING AQUIFER  

Science.gov (United States)

Two side-by-side field experiments were conducted in a shallow sulfate-reducing aquifer at a former service station site at Vandenberg Air Force Base, CA. On one side, we injected site groundwater amended with 1-3 mg/L benzene, toluene, and o-xylene (B, T, and o-X). On the othe...

96

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

97

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

International Nuclear Information System (INIS)

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

98

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

99

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: 0.76-0.8 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

100

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

 
 
 
 
101

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

Energy Technology Data Exchange (ETDEWEB)

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

Gonzalez Vanderhaghen, D.E

1998-12-31

102

Dynamics of an Oligotrophic Bacterial Aquifer Community during Contact with a Groundwater Plume Contaminated with Benzene, Toluene, Ethylbenzene, and Xylenes: an In Situ Mesocosm Study†  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An in situ mesocosm system was designed to monitor the in situ dynamics of the microbial community in polluted aquifers. The mesocosm system consists of a permeable membrane pocket filled with aquifer material and placed within a polypropylene holder, which is inserted below groundwater level in a monitoring well. After a specific time period, the microcosm is recovered from the well and its bacterial community is analyzed. Using this system, we examined the effect of benzene, toluene, ethylb...

Hendrickx, Barbara; Dejonghe, Winnie; Boe?nne, Wesley; Brennerova, Maria; Cernik, Miroslav; Lederer, Tomas; Bucheli-witschel, Margarete; Bastiaens, Leen; Verstraete, Willy; Top, Eva M.; Diels, Ludo; Springael, Dirk

2005-01-01

103

The effect of the potential fuel additive isobutanol on benzene, toluene, ethylbenzene, and p-xylene degradation in aerobic soil microcosms.  

Science.gov (United States)

Isobutanol is being considered as a fuel additive; however, the effect of this chemical on gasoline degradation (following a spill) has yet to be fully explored. To address this, the current study investigated the effect of isobutanol on benzene, toluene, ethylbenzene and p-xylene (BTEX) degradation in 14 sets of experiments in saturated soils. This involved four hydrocarbons for three soils (12 experiments) and two extra experiments with a lower level of isobutanol (for toluene only). Each soil and hydrocarbon combination involved four abiotic control microcosms and 12 sample microcosms (six with and six without isobutanol). The time for complete degradation of each hydrocarbon varied between treatments. Both toluene and ethylbenzene were rapidly degraded (5-13 days for toluene and 3-13 days for ethylbenzene). In contrast, the time for complete degradation for benzene ranged from 5 to 47 days. The hydrocarbon p-xylene was the most recalcitrant chemical (time for removal ranged from 14 to 86 days) and, in several microcosms, no p-xylene degradation was observed. The effect of isobutanol on hydrocarbon degradation was determined by comparing degradation lag times with and without isobutanol addition. From the 14 treatments, isobutanol only affected degradation lag times in three cases. In two cases (benzene and p-xylene), an enhancement of degradation (reduced lag times) was observed in the presence of isobutanol. In contrast, toluene degradation in one soil was inhibited (increased lag time). These results indicate that co-contamination with isobutanol should not inhibit aerobic BTEX degradation rates. PMID:25413118

Ding, Liang; Cupples, Alison M

2015-01-01

104

Biodegradation kinetics of benzene and toluene as single and mixed substrate: estimation of biokinetics parameters by applying particle swarm optimization  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english This paper aims to describe the microbial biodegradation kinetics of benzene and toluene as single and mixed substrates. Particle Swarm Optimization (PSO) is used as the parameter identification procedure. Initially, the Monod and Andrews models were used. To predict the interactions between the sub [...] strates, more sophisticated models of inhibition and the SKIP model were applied. The development of the changes on the competitive inhibition model was also described. The models were evaluated using experimental data on Pseudomonas putida F1 activity found in the literature. Simulation results showed that the best description of the biodegradation process of a pure substrate can be achieved by the Andrews model and in the case of a mixture by the modified competitive inhibition model. These results were expected because both substrates are catabolized by the same metabolic pathway through Pseudomonas putida F1. The SKIP model also captured the substrate interactions well. The performance of PSO was excellent and the methodology developed in this work can be considered as very efficient.

D.E.G., Trigueros; A.N., Módenes; M.A.S.S., Ravagnani.

2010-07-01

105

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

106

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-12-15

107

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

108

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 contai [...] ned the CYP2E1 transgene and the rolB gene of the Ri plasmid. Southern blotting revealed the presence of multiple copies of CYP2E1 in the genome of transgenic plants. Fluorescent quantitative PCR revealed exogenous CYP2E1 gene expression in CYP2E1 transgenic plants at various levels, whereas no like expression was detected in either GUS transgenic plants or wild-types. The absorption of benzene and toluene by transgenic plants was analyzed through quantitative gas chromatography. Transgenic plants with high CYP2E1 expression showed a significant increase in absorption capacity of environmental benzene and toluene, compared to control GUS transgenic and wild type plants. Furthermore, these plants also presented obvious improved resistance to formaldehyde. This study, besides being the first to reveal that the CYP2E1 gene enhances plant resistance to formaldehyde, also furnishes a new method for reducing pollutants, such as benzene, toluene and formaldehyde, by using transgenic flowering horticultural plants.

Daoxiang, Zhang; Taihe, Xiang; Li, Peihan; Lumin, Bao.

109

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

110

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.

111

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

112

Comparative Genomic Analysis and Benzene, Toluene, Ethylbenzene, and o-, m-, and p-Xylene (BTEX) Degradation Pathways of Pseudoxanthomonas spadix BD-a59  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pseudoxanthomonas spadix BD-a59, isolated from gasoline-contaminated soil, has the ability to degrade all six BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylene) compounds. The genomic features of strain BD-a59 were analyzed bioinformatically and compared with those of another fully sequenced Pseudoxanthomonas strain, P. suwonensis 11-1, which was isolated from cotton waste compost. The genome of strain BD-a59 differed from that of strain 11-1 in many characteristics, including th...

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

2013-01-01

113

Densities, viscosities, and excess properties of (N-methylmorpholine + cyclohexane, + benzene, and + toluene) at T = (298.15, 303.15, 313.15, 323.15) K  

International Nuclear Information System (INIS)

Densities, ?, and viscosities, ?, of binary mixtures (N-methylmorpholine + benzene, + toluene, and + cyclohexane) were measured over the whole mole fraction range at T = (298.15, 303.15, 313.15, 323.15) K. Densities and viscosities were used to compute the excess molar volumes VE, viscosity deviation ??, and the excess free energies of activation for viscous flow ?G*E. These data have been fitted to Redlich-Kister polynomial equation to derive the coefficients and estimate the standard deviation values. A discussion on these quantities in terms of molecular interactions is reported

114

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

Energy Technology Data Exchange (ETDEWEB)

In this paper, the separation of toluene from aliphatic hydrocarbons (heptane, or octane, or nonane) was analyzed by solvent extraction with 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid, [EMpy][ESO{sub 4}]. Liquid-liquid equilibrium (LLE) data for the ternary systems left braceheptane (1) + toluene (2) + [EMpy][ESO{sub 4}] (3)right brace, left braceoctane (1) + toluene (2) + [EMpy][ESO{sub 4}] (3)right brace, and left bracenonane (1) + toluene (2) + [EMpy][ESO{sub 4}] (3)right brace were obtained by measurements at T = 298.15 K and atmospheric pressure. The selectivity, % removal of aromatic, and solute distribution ratio, obtained from experimental equilibrium results, were used to determine the ability of [EMpy][ESO{sub 4}] as a solvent. The degree of consistency of the experimental LLE values was ascertained using the Othmer-Tobias and Hand equations. The experimental results for the ternary systems were correlated with the NRTL model. Finally, the results obtained were compared with other ionic liquids and other solvents.

Gonzalez, Emilio J. [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain); Calvar, Noelia [Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Facultade de Engenharia, Universidade de Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Gonzalez, Begona [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain); Dominguez, Angeles, E-mail: admguez@uvigo.e [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain)

2010-06-15

115

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

Energy Technology Data Exchange (ETDEWEB)

The ionic liquid 1-ethyl-3-methylpyridinium ethylsulfate, [EMpy][ESO{sub 4}], was studied for the separation of benzene from aliphatic hydrocarbons (octane or nonane) by solvent extraction through the determination of the (liquid + liquid) equilibrium (LLE) of the ternary systems: left braceoctane (1) + benzene (2) + [EMpy][ESO{sub 4}] (3)right brace and left bracenonane (1) + benzene (2) + [EMpy][ESO{sub 4}] (3)right brace at T = (283.15 and 298.15) K and atmospheric pressure. Binodal curves were determined using the 'cloud point' method, and tie-line compositions were obtained by density measurements. The values of selectivity and distribution coefficient, derived from the tie-line data, were used to decide if this ionic liquid can be used as potential solvent for the separation of benzene from aliphatic hydrocarbons using liquid extraction. These results were analyzed and compared to those previously reported for the systems left bracehexane + benzene + [EMpy][ESO{sub 4}]right brace and left braceheptane + benzene + [EMpy][ESO{sub 4}]right brace. The experimental results show that this ionic liquid is suitable for the extraction of benzene from mixtures containing octane and nonane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations. The experimental results for the ternary systems were well correlated with the NRTL model. No literature data were found for the mixtures discussed in this paper.

Gonzalez, Emilio J. [Departamento de Ingenieria Quimica, Universidad de Vigo, 36310 Vigo (Spain); Calvar, Noelia, E-mail: noecs@uvigo.e [Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Gomez, Elena [Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Dominguez, Angeles [Departamento de Ingenieria Quimica, Universidad de Vigo, 36310 Vigo (Spain)

2010-01-15

116

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

International Nuclear Information System (INIS)

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

117

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

118

Survival and reproduction of some blue-green and green algae as affected by sewage water, fertilizer factory effluent, brassica oil, phenol, toluene and benzene.  

Science.gov (United States)

Fourteen blue-green and green algae survived for widely different time periods ranging between 22-102 d in control culture medium. Irrespective of their long or short survival period in control cultures, their pro- or eukaryotic nature, their different morphological types or natural habitats, they all survived for a short time period ranging between 3-8 d in sewage water, 5-10 d in fertilizer factory effluent, (1/4)-2 d in brassica oil, (1/2)-2 d in phenol, 1-3 d in toluene, and 1-4 d in benzene (showing the relative toxicity of different chemicals to different algae, and the antialgal nature of brassica oil). Dilution decreased the toxicity of these agents very little, indicating that they all were very toxic to algae. None of the agent induced the formation of any reproductive or dormant cells. Sewage water, fertilizer factory effluent, brassica oil and/or benzene favored the formation of necridia cells in Phormidium bohneri, P. foveolarum, Microcoleus chthonoplastes, Lyngbya birgei, and L. major filaments. Scenedesmus quadricauda shed off all spines earlier, Hormidium flaccidum fragmented less or not at all, Scytonema millei formed no false branch and heterocyst, Aphanothece pallida and Gloeocapsa atrata cells did not divide, Cosmarium granatum cells did not form any zygospore and Oedogonium sp. not any oogonia-like cells under all or most of treatments with 25-100 % sewage water, 1-100 % fertilizer factory effluent, 1-100 % brassica oil, 25-100 % phenol, toluene and benzene. PMID:19330547

Agrawal, S C; Gupta, S

2009-01-01

119

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

120

Effects of inorganic nutrient levels on the biodegradation of benzene, toluene, and xylene (BTX) by Pseudomonas spp. in a laboratory porous media sand aquifer model.  

Science.gov (United States)

The effect of inorganic nutrients (sulfate, phosphate, and ammonium chloride) on the aerobic biodegradation of benzene, toluene, and xylene (BTX) by Pseudomonas spp. was studied in the laboratory using a glass sand tank. The increase of nutrient levels resulted in enhanced bacterial growth and BTX degradation. Sulfate and phosphate serve as key electron acceptors in the microbiological processes degrading BTX. The observed bacterial morphological changes during BTX degradation reveal that the filamentous bacteria were the dominant species at low temperatures about 20 degrees C. The spherical and rod-shaped cells became dominant at higher temperatures ranging from 25 degrees C to 28 degrees C. When the BTX mixture was allowed to be biodegraded for longer incubation periods of 21-42 h at high phosphate concentrations, large amounts of rod-shaped cells were clustered. The morphological adaptation appears to be controlled by the temperature and nutrient levels in the sandy medium where Pseudomonas spp. thrives. PMID:18329875

Jean, Jiin-Shuh; Lee, Ming-Kuo; Wang, Shih-Ming; Chattopadhyay, Pabitra; Maity, Jyoti Prakash

2008-11-01

 
 
 
 
121

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

122

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

123

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

Science.gov (United States)

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

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

2011-12-01

124

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

Science.gov (United States)

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

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

2013-01-01

125

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/ = K0 + K1X, have been measured as a function of concentration for the water-rich and benzene-rich solutions C6H6/H2O and C6H6/D2O and for the water-rich solutions C6D6/H2O and C6D6/D2O at several temperatures The constants K0 and K1 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 H2O- and D2O-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

126

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

127

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

International Nuclear Information System (INIS)

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

128

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

Science.gov (United States)

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach. PMID:18324831

Kütt, Agnes; Movchun, Valeria; Rodima, Toomas; Dansauer, Timo; Rusanov, Eduard B; Leito, Ivo; Kaljurand, Ivari; Koppel, Juta; Pihl, Viljar; Koppel, Ivar; Ovsjannikov, Gea; Toom, Lauri; Mishima, Masaaki; Medebielle, Maurice; Lork, Enno; Röschenthaler, Gerd-Volker; Koppel, Ilmar A; Kolomeitsev, Alexander A

2008-04-01

129

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 station attendants than any other scenario. PMID:24945191

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

2014-06-01

130

Materials Balance for Benzene: Level II.  

Science.gov (United States)

A Level II materials balance was performed on benzene. Data are reported for benzene production from petroleum by four processes (catalytic reformation, toluene dealkylation, toluene disproportionation, and isolation from pyrolysis gasoline) for productio...

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

1980-01-01

131

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

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A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxantho...

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

2008-01-01

132

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

133

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

Scientific Electronic Library Online (English)

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

R., Balzer; L. F. D., Probst; V., Drago; W. H., Schreiner; H. V., Fajardo.

2014-09-01

134

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

135

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

136

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

Scientific Electronic Library Online (English)

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

R., Balzer; L. F. D., Probst; V., Drago; W. H., Schreiner; H. V., Fajardo.

137

Response surface modeling of ultrasound-assisted dispersive liquid-liquid microextraction for determination of benzene, toluene and xylenes in water samples: Box-Behnken design.  

Science.gov (United States)

A simple, fast and effective pre-concentration procedure for the extraction of benzene, toluene and xylenes isomers (BTX) was developed using an ultrasound-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-flame ionization detector in water samples. The effects of different experimental parameters in the extraction step including type and volume of extraction and dispersive solvents, ionic strength, extraction time and sample volume were studied using two techniques, namely one-variable-at-a-time and response surface methodology. The results of "one-variable-at-a-time" showed that the ionic strength and extraction time were not significant on the extraction efficiency. Therefore, a three-factor, three-level Box-Behnken experimental design was employed to optimize the BTX extraction. The optimal conditions were determined to be a volume of extraction solvent (chloroform) of 51 ?L, volume of dispersive solvent (methanol) of 514 ?L and volume of sample of 12 mL. The enrichment factors of 241.2-305.1, the limit of detections of 205-382 ng L(-1) were obtained for the BTX at the optimum conditions. In addition, the relative standard deviations for 50 ?g L(-1) of the BTX in the water samples were found to be in the range of 1.9 %-5.7 % (n = 5). The developed procedure was then applied for the extraction and determination of BTX in the water samples. PMID:22555540

Khajeh, Mostafa; Zadeh, Fatemeh Musavi

2012-07-01

138

(1RS,6SR-Ethyl 4-(4-chlorophenyl-6-(4-fluorophenyl-2-oxocyclohex-3-ene-1-carboxylate toluene hemisolvate  

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Full Text Available In the crystal structure of the title compound, C21H18ClFO3·0.5C7H8, the toluene solvent molecules occupy special positions on centres of symmetry, and consequently are disordered across this site. The cyclohexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 72.90?(7° and their planes make dihedral angles of 30.09?(10 (chlorophenyl and 88.13?(6° (fluorophenyl with the approximately planar part of the cyclohexenone ring [maximum deviation from plane through five atoms is 0.030?(2?Å, the sixth atom is 0.672?(3Å out of this plane]. Weak intermolecular C—H...O and C—H...X (X = F, Cl interactions join molecules into a three-dimensional structure. Also, a relatively short and directional C—Cl...F—C contact is observed [Cl...F = 3.119?(2?Å, C—Cl...F = 157.5?(2° and C—F...Cl 108.3?(2°]. The solvent molecules fill the voids in the crystal structure and are kept there by relatively short and directional C—H...? interactions.

Grzegorz Dutkiewicz

2011-02-01

139

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  

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

Wouter A. Herrebout

2013-06-01

140

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

Scientific Electronic Library Online (English)

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

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

 
 
 
 
141

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

Directory of Open Access Journals (Sweden)

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

Marcelo Henrique Otenio

2005-09-01

142

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

143

Excess molar volumes of (acetophenone+benzene, or toluene, or 1,3-xylene, or 1,3,5-trimethylbenzene) at temperatures (298.15 and 328.15) K  

International Nuclear Information System (INIS)

The densities of (acetophenone+benzene, or toluene, or 1,3-xylene, or 1,3,5-trimethylbenzene) were measured at temperatures (298.15 and 328.15) K by means of a vibrating-tube densimeter. The excess molar volumes VmE calculated from the density data show that the deviations from ideal behaviour in the systems studied (all being negative) become more negative as the temperature is raised. The VmE results were correlated using the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters

144

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

Directory of Open Access Journals (Sweden)

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

Flamys Lena do N. Silva

2009-01-01

145

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

146

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  

International Nuclear Information System (INIS)

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 GE, 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

147

Sub-acute Toxicity Study of 3,6-Dimethyl-4-Ethyl-O-Acetyl Benzene Isolated from Soil Streptomyces Species  

Directory of Open Access Journals (Sweden)

Full Text Available The sub-acute toxicity study of 3,6-dimethyl-4-ethyl-0-acetyl benzene (BM-5, was carried out on Long Evan`s rats using daily administration (300 ?g/rat/day of compound for 14 consecutive days. Non-significant differences between weight of compound receiving rats and control rats (48?0.816 vs 46?0.816 were found. The change in hematological parameters was found to be nonsignificant (total count of RBC, 5.1?0.081 vs 4.63?0.094; white blood cell, 7.33?0.124 vs 5.73?0.124; platelets, 361666?10274 vs 261666?8498, (cell/ml ?106; percentage of hemoglobin 65.67?1.60 vs 56?0.816; ESR, 25?0.816 vs 19.67?0.471 for experimental and control rats, respectively and biochemical parameters (serum glutamate pyruvate transaminase, 8.5?0.408 vs 8.33 ?0.471 IU L-1; serum glutamate oxaloacetate transaminase, 9.83?0.235 vs 9.33?0.234 IU L-1; bilirubin, 0.36?0.104 vs 0.34?0.016 ?g dL-1; creatinine, 0.67 ?0.089 vs 0.61?0.009 mg dL-1; urea, 18.83?0.235 vs 18.5?0.408 mg dL-1; for experimental and control rats. Therefore, the changes in body weight, hematological and biochemical parameters were statistically non-significant. No detectable abnormalities were found in histopathology of heart, kidney, liver and lung in experimental group of rats as compared with that of the control group of rats.

Bytul M. Rahman

2002-01-01

148

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

Scientific Electronic Library Online (English)

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

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

149

Densities and Volumetric Properties of Binary Mixtures of Butyl Acrylate with Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Mesitylene at Temperatures from 288.15 K to 318.15 K  

Science.gov (United States)

The densities, ?, of binary mixtures of butyl acrylate (BA) with benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene, including those of pure liquids, over the entire composition range were measured at the temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K and atmospheric pressure. From the experimental data, the excess molar volumes, {V_m^E} were calculated. The {V_m^E} values were negative over the whole composition range for all the mixtures and at each temperature studied, except for BA + mesitylene which exhibit positive {V_m^E} values, indicating the presence of specific interactions between BA and aromatic hydrocarbon molecules. The deviations in {V_m^E} values follow the order: benzenep-xylene< m-xylene< o-xylene

Nain, Anil Kumar; Sharma, Rajni; Ali, Anwar; Gopal, Swarita

2010-06-01

150

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

Science.gov (United States)

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

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

2008-01-01

151

New polypyrrole-carbon nanotubes-silicon dioxide solid-phase microextraction fiber for the preconcentration and determination of benzene, toluene, ethylbenzene, and o-xylene using gas liquid chromatography.  

Science.gov (United States)

For the first time, a polypyrrole-carbon nanotubes-silicon dioxide composite film coated on a steel wire was prepared by an electrochemical method. Scanning electron microscopy images showed that this composite film was even and porous. The prepared fiber was used as an absorbent for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and o-xylene, followed by gas chromatographic analysis. This method presented an excellent performance, which was much better than that of a polypyrrole-carbon nanotube fiber. It was found that under the optimized conditions, the linear ranges were 0.01-200 ng/mL with correlation coefficients >0.9953, the detection limits were 0.005-0.020 ng/mL, the relative standard deviations were 3.9-6.4% for five successive measurements with a single fiber, and the reproducibility was 5.5-8.5% (n = 3). Finally, the developed method was successfully applied to real water samples, and the relative recoveries obtained for the spiked water samples were from 91.0 to 106.7%. PMID:24995551

Sarafraz-Yazdi, Ali; Rounaghi, Gholamhossein; Razavipanah, Iman; Vatani, Hossein; Amiri, Amirhassan

2014-09-01

152

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

Science.gov (United States)

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

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

2008-12-01

153

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

International Nuclear Information System (INIS)

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 13C NMR (nuclear magnetic resonance) is presented. (author)

154

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

155

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

156

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

157

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

Directory of Open Access Journals (Sweden)

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

Xin-Ping Kang

2010-11-01

158

Ethyl 3-[7-eth­oxy-6-(4-meth­oxy­benzene­sulfonamido)-2H-indazol-2-yl]propano­ate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C21H25N3O6S, the dihedral angle between the meth­oxy­benzene and indazole rings is 74.96?(5)°. The crystal packing is stabilized by an N—H?O hydrogen bond into a two-dimensional network. In addition, C—H?? inter­actions and a ?–? contact, with a centroid–centroid distance of 3.5333?(6)?Å, are observed. The crystal packing is stabilized by N—H?O and C—H?O hydrogen bonds.

Abbassi, Najat; Oulemda, Bassou; Rakib, El Mostapha; Geffken, Detlef; Zouihri, Hafid

2012-01-01

159

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

Scientific Electronic Library Online (English)

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

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

160

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

Scientific Electronic Library Online (English)

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

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

2012-06-01

 
 
 
 
161

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

Directory of Open Access Journals (Sweden)

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

Luis Haro-García

2012-06-01

162

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol.  

Science.gov (United States)

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated. PMID:24096064

Muthu, S; Renuga, S

2014-01-24

163

Characterization of anaerobic benzene-degrading cultures  

Energy Technology Data Exchange (ETDEWEB)

Microbial populations in 2 benzene-degrading consortia were characterized on a physiological and molecular level. Methanogenic and nitrate-reducing cultures were examined. The shortest doubling time of 8 to 9 days was observed in the nitrate-reducing cultures while the methanogenic cultures showed the highest substrate concentration and the maximum absolute rates of benzene degradation. The methanogenic culture also had 5 bacterial 16S rRNA sequences, of which 1 resembled a clone previously found in a sulphate-reducing benzene-degrading culture. Four bacterial and no archaeal 16S rRNA sequences were found in the nitrate-reducing culture. One clone was phylogenetically similar to both Azoarcus and Dechloromonas species. The study also isolated and characterized pure cultures that could anaerobically biodegrade benzene. Two cultures were successfully isolated from a nitrate-reducing enrichment culture. Both were capable of anaerobic benzene, toluene and benzoate degradation under nitrate-reducing conditions. The isolated pseudomonas was capable of aerobic benzene degradation and hydrogen utilization under nitrate-reducing conditions. The isolated and unidentified eubacterium clone did not appear to grow on any of the tested substrates. The study also identified the key metabolic processes in anaerobic benzene degradation. Studies with carbon isotopes showed that under methanogenic conditions, a pathway exists where benzene undergoes hydroxylation to phenol. Intermediates of benzene degradation were identified for nitrate-reducing conditions. This study presents the first evidence for a pathway where benzene undergoes methylation to toluene and further transformation to benzoate.

Ulrich, A.C.

2004-07-01

164

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.

2001-04-01

165

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.

166

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

167

Studies on the mechanism of benzene toxicity  

Energy Technology Data Exchange (ETDEWEB)

Using the 59Fe uptake method of Lee et al. it was shown that erythropoiesis in female mice was inhibited following IP administration of benzene, hydroquinone, p-benzoquinone, and muconaldehyde. Toluene protected against the effects of benzene. Coadministration of phenol plus either hydroquinone or catechol resulted in greatly increased toxicity. The combination of metabolites most effective in reducing iron uptake was hydroquinone plus muconaldehyde. We have also shown that treating animals with benzene leads to the formation of adducts of bone marrow DNA as measured by the 32P-postlabeling technique.

Snyder, R.; Dimitriadis, E.; Guy, R.; Hu, P.; Cooper, K.; Bauer, H.; Witz, G.; Goldstein, B.D. (Rutgers, State Univ. of New Jersey, Piscataway (USA))

1989-07-01

168

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

169

Identification of benzene metabolites in dermal fibroblasts as nonphenolic: regulation of cell viability, apoptosis, lipid peroxidation and expression of matrix metalloproteinase 1 and elastin by benzene metabolites.  

Science.gov (United States)

The skin is exposed to benzene and its derivatives, prevalent environmental chemicals. They may impair the structural integrity of the skin by increased expression of matrix metalloproteinase 1 (MMP-1; degrades structural collagen) and elastin, synthesized primarily by the dermal fibroblasts. We examined the metabolism of benzene in dermal fibroblasts and identified the benzene metabolites as toluene, benzaldehyde, aniline and benzoic acid. These metabolites were not toxic to the cells with regard to cell viability, apoptosis and lipid peroxidation, unlike the phenolic benzene metabolites (hydroquinone, t-butyl hydroquinone and phenol) or hydrogen peroxide. Toluene and phenol, which compose cigarette smoke, and benzaldehyde stimulated MMP-1 and/or elastin expression. In summary, the dermal fibroblasts metabolize benzene to nonphenolic metabolites that are less toxic to the cellular components than the phenolic benzene derivatives. Toluene, benzaldehyde and phenol can directly cause facial wrinkling and impaired structural integrity by upregulating MMP-1 and/or elastin. PMID:15087594

Philips, N; Burchill, D; O'Donoghue, D; Keller, T; Gonzalez, S

2004-01-01

170

{N,N?-Bis-[2-(di-phenyl-phosphan-yl)ethan-1-yl-idene]ethyl-enedi-amine}bromido-(p-toluene-sulfonyl-methyl isocyanide)iron(II) tetra-phenyl-borate  

Science.gov (United States)

In the title compound, [FeBr(C9H9NO2S)(C30H30N2P2)][B(C6H5)4], the FeII ion is in a distorted octa­hedral CBrN2P2 coordination geometry with a P—Fe—P angle of 109.95?(3)°. The relative orientation of the p-toluene­sulfonyl­methyl isocyanide ligand is defined by the C—S—C—N torsion angle of 67.1?(2)°. In the crystal, pairs of weak C—H?O hydrogen bonds connect the cations into inversion dimers, forming R 2 2(8) rings. PMID:24826104

Sues, Peter E.; Lough, Alan J.; Morris, Robert H.

2014-01-01

171

{N,N'-Bis-[2-(di-phenyl-phosphan-yl)ethan-1-yl-idene]ethyl-enedi-amine}bromido-(p-toluene-sulfonyl-methyl isocyanide)iron(II) tetra-phenyl-borate.  

Science.gov (United States)

In the title compound, [FeBr(C9H9NO2S)(C30H30N2P2)][B(C6H5)4], the Fe(II) ion is in a distorted octa-hedral CBrN2P2 coordination geometry with a P-Fe-P angle of 109.95?(3)°. The relative orientation of the p-toluene-sulfonyl-methyl isocyanide ligand is defined by the C-S-C-N torsion angle of 67.1?(2)°. In the crystal, pairs of weak C-H?O hydrogen bonds connect the cations into inversion dimers, forming R 2 (2)(8) rings. PMID:24826104

Sues, Peter E; Lough, Alan J; Morris, Robert H

2014-04-01

172

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

Scientific Electronic Library Online (English)

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

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

2010-03-01

173

Ethyl 2-acetylhydrazono-2-phenylacetate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C12H14N2O3, was synthesized as an intermediate for the synthesis of metamitron. The benzene ring forms dihedral angles of 86.3?(2 and 10.0?(3° with the ethyl group and the acetylimino plane, respectively. The crystal structure involves intermolecular C—H...O and N—H...O hydrogen bonds.

Liang-Zhong Xu

2008-01-01

174

Anaerobic benzene oxidation via phenol in Geobacter metallireducens  

DEFF Research Database (Denmark)

Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (<0.5 mu M) of phenol accumulated in cultures of Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with O-18 during growth in (H2O)-O-18, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation.

Zhang, Tian; Tremblay, Pier-Luc

2013-01-01

175

Anaerobic benzene oxidation via phenol in Geobacter metallireducens.  

Science.gov (United States)

Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with (18)O during growth in H2(18)O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation. PMID:24096430

Zhang, Tian; Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A; Bain, Timothy S; Lovley, Derek R

2013-12-01

176

Fenton-like initiation of a toluene transformation mechanism  

Science.gov (United States)

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

177

Deoxygenative reduction of carbon dioxide to methane, toluene, and diphenylmethane with [Et2Al]+ as catalyst.  

Science.gov (United States)

The strong Lewis acid [Et(2)Al](+) catalyzes the reduction of carbon dioxide with hydrosilanes under mild conditions to methane. In benzene solution, the side products toluene and diphenylmethane are also obtained through Lewis acid catalyzed benzene alkylation by reaction intermediates. PMID:22696242

Khandelwal, Manish; Wehmschulte, Rudolf J

2012-07-16

178

Ethyl 2-benzoyl-6-methylindolizine-7-carboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C19H17NO3, was synthesized using a tandem annulation reaction between 4-benzoyl-1H-pyrrole-2-carbaldehyde and (E-ethyl 4-bromobut-2-enoate under mild conditions. The dihedral angle between the benzene ring and the indolizine ring system is 41.73?(4°.

Shang-Tie Liao

2012-05-01

179

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

Science.gov (United States)

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-mass spectrometry analysis of m-cresol extracts showed that the oxygen in m-cresol was derived from molecular oxygen. Accordingly, this suggests that toluene-3-monooxygenation is the first step in the degradative pathway. Toluene-3-monooxygenase activity is positively regulated from a locus designated tbuT. Induction of the toluene-3-monooxygenase is mediated by either toluene, benzene, ethylbenzene, or m-cresol. Moreover, toluene-3-monooxygenase activity induced by these effectors also metabolizes benzene and ethylbenzene to phenol and 3-ethylphenol, respectively, and also after induction, o-xylene, m-xylene, and p-xylene are metabolized to 3,4-dimethylphenol, 2,4-dimethylphenol, and 2,5-dimethylphenol, respectively, although the xylene substrates are not effectors. Styrene and phenylacetylene are transformed into more polar products. PMID:8206853

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

1994-06-01

180

Effect of birefringence dispersion on the selectivity of benzene absorption measurements using interference-polarization filters  

Science.gov (United States)

A technique for calculating absorption interference patterns of aromatic hydrocarbons with allowance for the birefringence dispersion of an interference-polarization filter is proposed. An experimental model of an optical absorption gas analyzer based on a Wood filter with magnesium-fluoride plates for measuring benzene and toluene characteristics is described. The measurement data are compared with the calculation results. The possibility of applying a combined plate to improve the selectivity of absorption measurements for benzene with respect to toluene is considered.

Kolesnikov, S. A.; Kolesnikova, E. S.; Pisarevsky, Yu. V.; Turutin, Yu. A.

2013-11-01

 
 
 
 
181

Preparation of toluenes specifically labelled with C-14  

International Nuclear Information System (INIS)

The attempt to prepare toluene-2 C-14 starting from ethyl acetoacetate failed because the reaction of sodium ethyl acetoacetate with dibromopropane could not be performed. This labelling was also attempted starting from methyl tetrahydropyran. This synthesis was not successful because the preparationof 2-methyl pimelic acid was impossible. Labellimg of carbon-3 of toluene starting from succinic acid could not be carried out because the Grignard reaction of a-ketoglutaric acid as unsuccessful. The radioactive syntheses started from propanediol resp. from c-butyrolactone. (The labelling of carbon-3 of toluene was not possible in this case because the reduction of malonic acid to propanediol could not be carried out). The synthesis course was identical for all labellings. The synthesis differed only in the introduction of the activiy from potassium cyanide C-14. The starting compounds were reacted to propanedinitril, which was saponified to glutaric acid. The acid was reduced to pentanediol. From the diol, dibromopentane was produced. Reaction with potassium cyanide yielded, after saponification, pimelic acid. The acid was cyclizated to cyclohexanone, which was reduced to cyclohexanol. The OH group was replaced by bromine and subsequently by a methyl group. Dehydration yielded toluene. The following labellings were carried out: Toluene-2, -2.6, -1.2.6, -1.2 C-14. (G.G.)

182

Final amended report of the safety assessment of toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine as used in cosmetics.  

Science.gov (United States)

Toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine are diaminotoluenes used as colorants in permanent hair dyes and tints. Toluene-2,5-diamine is used in 79 products at concentrations up to 3%; toluene-2,5-diamine sulfate is used in 168 products at concentrations up to 4%. Toluene-3,4-diamine does not appear to be in current use. Previously, the Cosmetic Ingredient Review Expert Panel determined that all 3 ingredients were safe for use as hair dyes. New data suggest that differences in toxicity, especially with respect to carcinogenicity, may exist as a function of placement of amine groups around the benzene ring. The Expert Panel concluded that toluene-2,5-diamine and toluene-2,5-diamine sulfate and are safe as hair dye ingredients in the present practices of use and concentrations but that there are insufficient data supporting the safety of toluene-3,4-diamine. PMID:20448268

Burnett, Christina L; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Alan Andersen, F

2010-05-01

183

Toluene removal biofilter modeling.  

Science.gov (United States)

On the basis of the model proposed by De Visscher and Van Cleemput for methane oxidation in landfill cover soils, simulation models for biofiltration of toluene-contaminated air were performed for biofilters with or without substrate inhibition and operated at constant or varying airflow rates. The toluene oxidizing activity (V(max)) expressions of the derived models clearly indicate that V(max) is not a constant along a biofilter height. The equations derived when V(max) is set to zero can be used to predict the minimum concentration requirement for a viable biofiltration process. The simulation results show that the model of De Visscher and Van Cleemput, modified to incorporate Haldane kinetics, provides a good description of the biofiltration performance for toluene removal biofilters. Predictions of the minimum concentration that can be treated indicate that conventional biofilters are not suitable for indoor air pollutant removal. PMID:18672719

Li, Gui Qin; De Visscher, Alex

2008-07-01

184

Irradiation of benzene with 14CH+ and 14CH3+ ions  

International Nuclear Information System (INIS)

Solid benzene at -1960C was irradiated with 14CH+ and 14CH3+ ions in 10-eV kinetic energy. Yields were determined for the labeled hydrocarbon products: benzene, toluene, cycloheptatriene, diphenylmethane, biphenyl, and phenylcycloheptatriene. The radioactivity distributions between the ring and the methyl group of the toluene product were also determined. These results have been compared to those previously obtained with 14C+ and 14CH2+ ions. The comparisons have provided both insight into the reaction mechanisms and a tentative estimate of the distribution of the species (14CH/sub x/) that react with the benzene

185

CFD SIMULATIONS OF BENZENETOLUENE 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

186

The oxidation of toluene on transition metal oxides  

Science.gov (United States)

The oxidation of toluene on pure vanadium and molybdenum oxides was found to follow independent paths; it was benzene ring oxidation on V2O5 and side chain oxidation on MoO3. On mixed xV2O5 · yMoO3 oxides, the main reaction was the addition at the double bond preferably positioned meta rather than one-electron oxidation.

Tomskii, I. S.; Vishnetskaya, M. V.; Rufov, Yu. N.

2009-11-01

187

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Condensações de Knoevenagel de aldeídos aromáticos com 4-cloro-3-oxobutanoato de etila catalisadas por morfolina/ácido acético foram conduzidas em líquidos iônicos para fornecerem 2-cloroacetil-3-arilpropenoatos de etila em 44 a 84% de rendimentos após 0,5 a 2 h à temperatura ambiente (25-28 ºC). Es [...] tas condições representam um protocolo mais verde para a condensação de Knoevenagel do que aquelas realizadas com refluxo de benzeno e tolueno, utilizados como solventes. Aldeídos aromáticos contendo grupos arila, 4-clorofenila, 4-metoxifenila, 2-tiofuranila, 2-furanila, fenila e 3,4-metilenodioxifenila apresentaram razões diastereoméricas (E)/(Z) de 56/44 a 85/15. A estrutura do isômero-(E) do 2-cloroacetil-3-(3',4'-metilenodioxifenil)propenoato de etila foi determinada por difração de raio X, e uma metodologia inequívoca da análise estrutural-(E)/(Z) por RMN de 13C (ressonância magnética nuclear) é apresentada. Abstract in english 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 ºC). These conditions represent a greene [...] r 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 13C NMR (nuclear magnetic resonance) is presented.

Bruno R. S. de, Paula; Dávila S., Zampieri; Julio, Zukerman-Schpector; Edward R. T., Tiekink; José Augusto R., Rodrigues; Paulo J. S., Moran.

2012-05-01

188

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Condensações de Knoevenagel de aldeídos aromáticos com 4-cloro-3-oxobutanoato de etila catalisadas por morfolina/ácido acético foram conduzidas em líquidos iônicos para fornecerem 2-cloroacetil-3-arilpropenoatos de etila em 44 a 84% de rendimentos após 0,5 a 2 h à temperatura ambiente (25-28 ºC). Es [...] tas condições representam um protocolo mais verde para a condensação de Knoevenagel do que aquelas realizadas com refluxo de benzeno e tolueno, utilizados como solventes. Aldeídos aromáticos contendo grupos arila, 4-clorofenila, 4-metoxifenila, 2-tiofuranila, 2-furanila, fenila e 3,4-metilenodioxifenila apresentaram razões diastereoméricas (E)/(Z) de 56/44 a 85/15. A estrutura do isômero-(E) do 2-cloroacetil-3-(3',4'-metilenodioxifenil)propenoato de etila foi determinada por difração de raio X, e uma metodologia inequívoca da análise estrutural-(E)/(Z) por RMN de 13C (ressonância magnética nuclear) é apresentada. Abstract in english 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 ºC). These conditions represent a greene [...] r 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 13C NMR (nuclear magnetic resonance) is presented.

Bruno R. S. de, Paula; Dávila S., Zampieri; Julio, Zukerman-Schpector; Edward R. T., Tiekink; José Augusto R., Rodrigues; Paulo J. S., Moran.

189

Health aspects of toluene and xylene exposures associated with motor gasoline  

Energy Technology Data Exchange (ETDEWEB)

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

Eyres, A.R.

1987-01-01

190

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

191

(E-Ethyl 4-[4-(diethylaminostyryl]benzoate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title molecule, C21H25NO2, the dihedral angle between the two benzene rings is 4.8?(2°. Both the ethyl group of the ester group and one of the ethyl groups attached to the N atom are disordered over two sites, the approximate occupancies being 66:34 and 81:19, respectively. In the cystal structure, there are no direction-specific interactions.

Yong-Yan Yao

2008-01-01

192

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.

193

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

194

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

International Nuclear Information System (INIS)

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

195

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

Energy Technology Data Exchange (ETDEWEB)

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several investigators have demonstrated that a combination of metabolites (hydroquinone and phenol, for example) is necessary to duplicate the hematotoxic effect of benzene. Enzymes implicated in the metabolic activation of benzene and its metabolites include the cytochrome P450 monooxygenases and myeloperoxidase. Since benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. Other organic molecules that are substrates for cytochrome P450 can inhibit the metabolism of benzene. For example, toluene has been shown to inhibit the oxidation of benzene in a noncompetitive manner. Enzyme inducers, such as ethanol, can alter the target tissue dosimetry of benzene metabolites by inducing enzymes responsible for oxidation reactions involved in benzene metabolism. 24 refs., 6 figs., 2 tabs.

Medinsky, M.A.; Schlosser, P.M.; Bond, J.A. [Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)

1994-11-01

196

Anaerobic degradation of toluene and o-xylene by a methanogenic consortium  

Energy Technology Data Exchange (ETDEWEB)

Toluene and o-xylene were completely mineralized to stoichiometric amounts of carbon dioxide, methane, and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was creosote-contaminated sediment from Pensacola, Fla. The adaptation periods before the onset of degradation were long (100 to 120 days for toluene degradation and 200 to 255 days for o-xylene). Successive transfers of the toluene- and o-xylene-degrading cultures remained active. Cell density in the cultures progressively increased over 2 to 3 years to stabilize at approximately 10[sup 9] cells per ml. Degradation of toluene and o-xylene in stable mixed methanogenic cultures followed Monod kinetics, with inhibition noted at substrate concentrations above about 700 [mu]M for o-xylene, and 1,800 [mu]M for toluene. The cultures degraded toluene or o-xylene but did not degrade m-xylene, p-xylene, benzene, ethylbenzene, or naphthalene. The degradative activity was retained after pasteurization or after starvation for 1 year. Degradation of toluene and o-xylene was inhibited by the alternate electron acceptors oxygen, nitrate, and sulfate. Degradation was also inhibited by the addition of preferred substrates such as acetate, H[sub 2] propionate, methanol, acetone, glucose, amino acids, fatty acids, peptone, and yeast extract. These data suggest that the presence of natural organic substrates or cocontaminants may inhibit anaerobic degradation of pollutants such as toluene and o-xylene at contaminated sites.

Edwards, E.A.; Grbic-Galic, D. (Stanford Univ., CA (United States))

1994-01-01

197

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

198

Quantification of urinary metabolites of principle superior counterpart of benzene; Dosage des metabolites urinaires des principaux homologues superieurs du benzene  

Energy Technology Data Exchange (ETDEWEB)

In the aim of a medical surveillance of personnel exposed to superior counterpart of benzene, it is advisable to measure in urines, the hippuric, methyl hippuric and mandelic acids, as respective biological indicators of exposure to toluene, to xylenes and styrene (chapter 1). In a first time, we give some generalities on principal superior counterparts of benzene and about the biological surveillance of workers exposed to these products. Then, we present the quantification of their urinary metabolites, as it has be done in the stage. (N.C.)

Ruetsch, O. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Dept. de Protection de la Sante de l`Homme et de Dosimetrie]|[Lille-2 Univ., 59 (France)

1997-12-31

199

Peripheral blood effects in benzene-exposed workers.  

Science.gov (United States)

The hematotoxic effects of benzene exposure may be important in the occurrence of subsequent health effects. We sought to provide further information on peripheral blood effects by studying 928 workers in five factories in and around Shanghai, China exposed to a wide range of benzene concentrations. Specifically, we sought to investigate which blood indices are more strongly related to benzene exposure and which concentration levels of benzene result in peripheral blood changes. Lifestyle habits and demographic information was obtained via questionnaire, and potentially important genetic influences were determined by assessing single nucleotide polymorphisms in four genes (NQO1, MPO, CYP2E1, GSTT1). Weekly benzene exposure estimated from individual monitoring results ranged from 0.07 to 872 mg/m(3) with a median value of 7.4 mg/m(3). Twelve peripheral blood indices were examined. Stronger effects on peripheral blood were seen for red cell indices such as anemia and macrocytosis, albeit at higher (>10 ppm) exposure levels. The most sensitive parameters to benzene appeared to be neutrophils and the mean platelet volume (MPV), where effects were seen for benzene air concentrations of 7.8-8.2 ppm. Toluene exposure is a potential confounder for some peripheral blood effects, pointing to the need to scrutinize levels of both compounds in the occupational environment. PMID:20034484

Robert Schnatter, A; Kerzic, Patrick J; Zhou, Yimei; Chen, Min; Nicolich, Mark J; Lavelle, Karlene; Armstrong, Thomas W; Bird, Michael G; Lin, Lv; Fu, Hua; Irons, Richard D

2010-03-19

200

Anaerobic degradation of benzene by marine sulfate-reducing bacteria  

Science.gov (United States)

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

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

2010-05-01

 
 
 
 
201

Alkylation of benzene with carbon monoxide over Zn/H-ZSM-5 zeolite studied using in situ solid-state NMR spectroscopy.  

Science.gov (United States)

Using in situ solid-state NMR spectroscopy we show that CO can act as an alkylating reagent and react with benzene to produce toluene over a Zn/H-ZSM-5 zeolite. In the alkylation reaction, CO provides the methyl group of toluene via a methoxy intermediate. PMID:25126651

Wang, Xiumei; Xu, Jun; Qi, Guodong; Wang, Chao; Wang, Qiang; Deng, Feng

2014-10-01

202

Benzene contamination at a metal plating facility  

Science.gov (United States)

A metal plating facility in central Kentucky was required to complete a RCRA Facility Investigation to address a number of Solid Waste Management Units at the site. Twenty monitoring wells were installed at the facility. Ground water from the wells was sampled for total and dissolved metals, polychlorinated biphenyls, acid extractable compounds, base neutral compounds, and volatile organic compounds. Unexpectedly, relatively large concentrations of benzene, up to 120 ?g/l, were detected in samples from some of the wells, including wells that should have been hydraulically upgradient from the facility. As a result of the detection of benzene, the facility completed an investigation to identify the source. A nearby facility had completed a gasoline underground storage tank (UST) closure at about the time of the installation of the 20 wells. Reportedly the UST had small holes when removed. Three potential pathways of migration (a ditch, sanitary sewer, and a sink hole) from the nearby facility to the metal-plating facility and residual soils with very large concentrations of benzene, toluene, ethylbenzene, and xylenes have been identified.

Memon, B. A.; Burston, M. R.

2005-08-01

203

Consistent assignment of the vibrations of monosubstituted benzenes.  

Science.gov (United States)

We investigate the consistency of the labeling and assignments of the vibrations of the monosubstituted benzenes in the electronic ground state. In doing so, we also identify some inconsistencies in the labeling of the benzene modes. We commence by investigating the behavior of the benzene vibrations as one hydrogen is replaced by an artificial atomic substituent of increasing mass via quantum chemical calculations; the wavenumber variations with mass give insight into the assignments. We also examine how well the monohalobenzene vibrations can be described in terms of the benzene ones: consistent with some recent studies, we conclude that this is futile in a significant number of cases. We then show that "isotopic wavenumbers" obtained by artificially changing the mass of the fluorine atom in fluorobenzene are in very good agreement with the wavenumbers obtained via explicit calculation for the relevant monohalobenzene (chlorobenzene, bromobenzene, and iodobenzene) vibrations. As a consequence, we propose that the vibrations of monofluorobenzene be used as the basis for labelling the vibrational assignments of monosubstituted benzenes. As well as the four monohalobenzenes, we also apply this approach to the vibrations of aniline, toluene, benzonitrile, phenylacetylene, phenylphosphine, and nitrobenzene. This has allowed a much more consistent picture of the vibrational assignments to be obtained across ten monosubstituted benzenes. PMID:21950860

Gardner, Adrian M; Wright, Timothy G

2011-09-21

204

Consistent assignment of the vibrations of monosubstituted benzenes  

Science.gov (United States)

We investigate the consistency of the labeling and assignments of the vibrations of the monosubstituted benzenes in the electronic ground state. In doing so, we also identify some inconsistencies in the labeling of the benzene modes. We commence by investigating the behavior of the benzene vibrations as one hydrogen is replaced by an artificial atomic substituent of increasing mass via quantum chemical calculations; the wavenumber variations with mass give insight into the assignments. We also examine how well the monohalobenzene vibrations can be described in terms of the benzene ones: consistent with some recent studies, we conclude that this is futile in a significant number of cases. We then show that ``isotopic wavenumbers'' obtained by artificially changing the mass of the fluorine atom in fluorobenzene are in very good agreement with the wavenumbers obtained via explicit calculation for the relevant monohalobenzene (chlorobenzene, bromobenzene, and iodobenzene) vibrations. As a consequence, we propose that the vibrations of monofluorobenzene be used as the basis for labelling the vibrational assignments of monosubstituted benzenes. As well as the four monohalobenzenes, we also apply this approach to the vibrations of aniline, toluene, benzonitrile, phenylacetylene, phenylphosphine, and nitrobenzene. This has allowed a much more consistent picture of the vibrational assignments to be obtained across ten monosubstituted benzenes.

Gardner, Adrian M.; Wright, Timothy G.

2011-09-01

205

The cyanogen-ethylation  

International Nuclear Information System (INIS)

The substitution of agile hydrogen atom of different organic compounds on ?-cyanogen-ethyl group at the action of nitril of acrylic acid is the reaction of cyanogen-ethylation. The process is running on ion mechanism, where nucleophilic attack on ?-carbonic atom of acrylonitrile carry out by joining with agile hydrogen atom

206

Benzene release. status report  

Energy Technology Data Exchange (ETDEWEB)

Scoping benzene release measurements were conducted on 4 wt percent KTPB `DEMO` formulation slurry using a round, flat bottomed 100-mL flask containing 75 mL slurry. The slurry was agitated with a magnetic stirrer bar to keep the surface refreshed without creating a vortex. Benzene release measurements were made by purging the vapor space at a constant rate and analyzing for benzene by gas chromatography with automatic data acquisition. Some of the data have been rounded or simplified in view of the scoping nature of this study.

Dworjanyn, L.O. [Westinghouse Savannah River Company, AIKEN, SC (United States); Rappe, K.G.; Gauglitz, P.A. [Pacific Northwest National Lab., Richland, WA (United States)

1997-11-04

207

Transformation of microflora during degradation of gaseous toluene in a biofilter detected using PCR-DGGE.  

Science.gov (United States)

A laboratory-scale biofiltration system, the rotatory-switching biofilter (RSB), was operated for 199 days using toluene as a model pollutant. The target gaseous pollutant for the biofiltration experiment was approximately 300 ppmv of toluene. Toluene removal efficiency (RE, %) was initially approximately 20% with a 247-ppmv concentration (0.9 g m(-3)) of toluene during the first 10 days. Although the RE decreased several times whenever nitrogen was consumed, it again reached almost 100% when the nitrogen source was in sufficient supply. Denaturing gradient gel electrophoresis (DGGE) analysis was employed to assess the transformation ofmicroflora during operation of the biofilter The results based on a 16S rRNA gene profile showed that the microbial community structure changed with operation time. Although the microflora changed during the initial period (before day 40), transformation of the bacterial component was hardly observed after day 51. Statistical analyses of the DGGE profiles indicated that the bacterial community was almost unaffected by the environmental factors, such as adding ozone, high-level nitrogen supply, increase of loading toluene, and the shutdown of the RSB. The DGGE profile using tmoA-like genes, which encode proteins belonging to the hydroxylase component mono-oxygenases involved in the initial attack of aerobic benzene, toluene, ethylbenzene, and xylene degradation, confirmed the existence of toluene-degrading bacteria. There were at least four kinds of toluene-degradable bacteria having tmoA-like genes up to day 36, which decreased to two species after day 40. Sequence analysis after DGGE profiling revealed that Burkholderia cepacia, Sphingobacterium multivorum, and Pseudomonas putida were present in the biofilter. Only Alicycliphilus denitrificans was present throughout the whole operation period. In the initial stage of operating the RSB, many types of bacteria may have tried to adapt to the conditions, and subsequently, only selected bacteria were able to grow and to degrade toluene. PMID:22866576

Okunishi, Suguru; Morita, Yasutaka; Higuchi, Takashi; Maeda, Hiroto; Nishi, Katsuji

2012-07-01

208

40 CFR 268.40 - Applicability of treatment standards.  

Science.gov (United States)

...other catalytic reactors (this listing does not include inert support media).Benz(a)anthraceneBenzeneChrysene...other catalytic reactors (this listing does not include inert support media.).BenzeneEthyl benzeneToluene...

2010-07-01

209

Ethyl 2-acetyl-hydrazono-2-phenyl-acetate.  

Science.gov (United States)

The title compound, C(12)H(14)N(2)O(3), was synthesized as an inter-mediate for the synthesis of metamitron. The benzene ring forms dihedral angles of 86.3?(2) and 10.0?(3)° with the ethyl group and the acetyl-imino plane, respectively. The crystal structure involves inter-molecular C-H?O and N-H?O hydrogen bonds. PMID:21200890

Xu, Liang-Zhong; Yi, Xu; An, Guang-Wei; Zhang, Gong-Sheng; Li, Chun-Fang

2007-01-01

210

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...

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

1997-01-01

211

Ethyl 2-(4-nitrobenzamidobenzoate, a non-merohedral twin  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C16H14N2O5, a non-merohedral twin, the dihedral angle between the mean planes of the two benzene rings is 4.0?(9°. The ethyl group is disordered [0.643?(14 and 0.357?(14 occupancy]. The nitro group is twisted by 16.4?(4° from the mean plane of the benzene ring and the mean plane of the carbonyl group is twisted from the mean planes of the two benzene rings by 4.5?(0 and 4.7?(9°. An intramolecular N—H...O hydrogen bond occurs. The crystal packing is stabilized by weak intermolecular C—H...O hydrogen-bond interactions.

Sohail Saeed

2011-02-01

212

Steam reforming of toluene as model compound of biomass pyrolysis tar for hydrogen  

International Nuclear Information System (INIS)

Steam reforming of tar during biomass pyrolysis for hydrogen will not only avoid frequent equipment shutdown for maintenance and repair but also increase hydrogen yield. In this paper, the effects of temperature and steam/carbon molar ration on steam reforming of toluene as model compound of tar was studied by simulation of thermodynamic equilibrium and experiments using Ni/cordierite catalyst in a fixed bed reactor. The results of thermodynamic simulations indicate that the S/C molar ratio of 2 and the temperature range from 1023 K to 1173 K provide favorable operating conditions for steam reforming of toluene in order to get high hydrogen productivity. These operating parameters were adopted in the experiments using Ni/cordierite catalyst in a fixed bed reactor. H2 content remains about 66 mol% and slightly varies with the increasing temperature. Conversion efficiency of toluene increases with temperature, reaching 94.1% at 1173 K. The simulation was improved in order to be closer to experimental results. It is found that only a very small amount of toluene did not participate in the reaction. In the aromatic hydrocarbons of reactive system, benzene and naphthalene were the main products and the proportion of naphthalene decreases with increasing temperature while that of benzene increases.

213

HCCI experiments with toluene reference fuels modeled by a semidetailed chemical kinetic model  

Energy Technology Data Exchange (ETDEWEB)

A semidetailed mechanism (137 species and 633 reactions) and new experiments in a homogeneous charge compression ignition (HCCI) engine on the autoignition of toluene reference fuels are presented. Skeletal mechanisms for isooctane and n-heptane were added to a detailed toluene submechanism. The model shows generally good agreement with ignition delay times measured in a shock tube and a rapid compression machine and is sensitive to changes in temperature, pressure, and mixture strength. The addition of reactions involving the formation and destruction of benzylperoxide radical was crucial to modeling toluene shock tube data. Laminar burning velocities for benzene and toluene were well predicted by the model after some revision of the high-temperature chemistry. Moreover, laminar burning velocities of a real gasoline at 353 and 500 K could be predicted by the model using a toluene reference fuel as a surrogate. The model also captures the experimentally observed differences in combustion phasing of toluene/n-heptane mixtures, compared to a primary reference fuel of the same research octane number, in HCCI engines as the intake pressure and temperature are changed. For high intake pressures and low intake temperatures, a sensitivity analysis at the moment of maximum heat release rate shows that the consumption of phenoxy radicals is rate-limiting when a toluene/n-heptane fuel is used, which makes this fuel more resistant to autoignition than the primary reference fuel. Typical CPU times encountered in zero-dimensional calculations were on the order of seconds and minutes in laminar flame speed calculations. Cross reactions between benzylperoxy radicals and n-heptane improved the model predictions of shock tube experiments for {phi}=1.0 and temperatures lower than 800 K for an n-heptane/toluene fuel mixture, but cross reactions had no influence on HCCI simulations. (author)

Andrae, J.C.G. [Department of Chemical Engineering and Technology, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden); Brinck, T. [Department of Physical Chemistry, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden); Kalghatgi, G.T. [Shell Global Solutions (UK), P.O. Box 1, Chester CH1 3SH (United Kingdom)

2008-12-15

214

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

215

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

216

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

217

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

218

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

219

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

220

Methane from benzene in argon dielectric barrier discharge.  

Science.gov (United States)

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. PMID:23419905

Das, Tomi Nath; Dey, G R

2013-03-15

 
 
 
 
221

Toluene adsorption on Ni(111)  

Science.gov (United States)

The adsorption of toluene on Ni(111) at 110 K has been studied by reflection absorption infrared spectroscopy (RAIRS). These data show that the presence of the methyl group significantly disrupts the ?-interaction of the aromatic ring with the substrate, leading to a weakly adsorbed molecule in which only the CH 3 group is significantly perturbed by the presence of the metal surface. Toluene is initially adsorbed with its aromatic ring parallel to the surface. Increased coverage in the first layer leads to slight tilting of the aromatic ring towards both the x- z and y- z planes, where z is defined as the surface normal. This molecular geometry persists in the multilayers when adsorption is carried out at 110 K. However, annealing the multilayers leads to a reorientation of the molecules whereby the aromatic ring preferentially tilts away from the surface about the axis perpendicular to the Ph-Me bond.

Coats, A. M.; Cooper, E.; Raval, R.

1994-04-01

222

Synthesis of B/Si bidentate Lewis acids, o-(Fluorosilyl)(dimesitylboryl)benzenes, and their fluoride ion affinity.  

Science.gov (United States)

o-(Fluorosilyl)(dimesitylboryl)benzenes have been prepared as colorless crystals by reacting fluorodimesitylborane with o-(fluorodimethylsilyl)phenyllithium and o-(fluorodiphenylsilyl)phenyllithium. The o-(fluorosilyl)(dimesitylboryl)benzenes serve as B/Si bidentate Lewis acid and efficiently capture fluoride ion from potassium fluoride in the presence of [2.2.2]cryptand or 18-crown-6 in toluene, giving the corresponding mu-fluoro bridged products. The structures were characterized by X-ray crystal structure analysis and multinuclear NMR spectroscopy. Fluoride ion affinities of the o-(fluorosilyl)(dimesitylboryl)benzenes were evaluated in comparison with non-silylated triarylborane. PMID:18327943

Kawachi, Atsushi; Tani, Atsushi; Shimada, Junpei; Yamamoto, Yohsuke

2008-04-01

223

Índicesde refracción y densidad de mezclas binarias de heptano con ciclohexano, benceno y tolueno a 293.15, 298.15, 303.15 y 308.15 K / Refraction indexes and density for binary mixtures of heptane with cyclohexane, benzene and toluene at 293.15, 298.15, 303.15 K / Índices derefração e densidade de misturas binárias de heptano com ciclo-hexano, benzenoe tolueno a 293.15, 298.15, 303.15 e 308.15 K  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in portuguese Determinam-sedensidades e índices de refração de misturas binárias de ciclo-hexano, benzenoe tolueno com heptano a (293.15, 298.15, 303.15 e 308.15) K. Se calcularem osvolumes de excesso molar e o cambio do índice de refração (??D) a partir dosdados experimentais e ajustados à uma equação polinomial [...] de Redlich-Kister deordem quatro. Abstract in spanish Semidieron densidades e índices de refracción de mezclas binarias de ciclohexano,benceno y tolueno con heptano a (293.15, 298.15, 303.15 y 308.15) K. El volumende exceso molar y el cambio de índice de refracción (??D) son calculados desdelos datos experimentales y ajustados con una ecuación polinomi [...] al deRedlich-Kister de orden cuatro. Abstract in english Density and refraction indexes forbinary mixtures of cyclohexane, benzene and toluene with heptane (293.15, 298.15,303.15 and 308.15 K) were measured. Excess molar volume and refraction indexchange (??D) werecalculated from experimental data and adjusted with a fourth-orderRedlich-Kister polynomial [...] equation.

Marlon D., Martínez-Reina; Eliseo, Amado-González.

2012-06-01

224

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 methyld 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)

225

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

Science.gov (United States)

We commence by presenting an overview of the assignment of the vibrational frequencies of the toluene molecule in its ground (S0) state. The assignment given is in terms of a recently proposed nomenclature, which allows the ring-localized vibrations to be compared straightforwardly across different monosubstituted benzenes. The frequencies and assignments are based not only on a range of previous work, but also on calculated wavenumbers for both the fully hydrogenated (toluene-h8) and the deuterated-methyl group isotopologue (?3-toluene-d3), obtained from density functional theory (DFT), including artificial-isotope shifts. For the S1 state, one-colour resonance-enhanced multiphoton ionization (REMPI) spectroscopy was employed, with the vibrational assignments also being based on previous work and time-dependent density functional theory (TDDFT) calculated values; but also making use of the activity observed in two-colour zero kinetic energy (ZEKE) spectroscopy. The ZEKE experiments were carried out employing a (1 + 1') ionization scheme, using various vibrational levels of the S1 state with an energy chlorobenzene.

Gardner, Adrian M.; Green, Alistair M.; Tamé-Reyes, Victor M.; Wilton, Victoria H. K.; Wright, Timothy G.

2013-04-01

226

Dealkylation of Alkylbenzenes: A Significant Pathway in the Toluene, o-, m-, p-Xylene + OH Reaction  

Science.gov (United States)

The OH-radical initiated oxidation of a series of monocyclic aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylene) in the presence of oxygen and NOx was investigated in a flowtube coupled with a chemical ionization mass spectrometer (CIMS). OH-radical addition to the aromatic ring - the major reaction pathway - has previously been shown to have a particular sensitivity to experimental conditions. This is the first flowtube study that demonstrates the atmospheric relevance of product yields from the OH-addition channel on the millisecond time scale (35-75 ms); the phenol yield from benzene and cresol yields from toluene are found to be 51.0 ± 4.3% and 17.7 ± 2.1%, in excellent agreement with previous studies under close to atmospheric conditions. We further report unambiguous experimental evidence that dealkylation is a novel and significant pathway for toluene and o-, m-, and p-xylene oxidation. At 150 Torr of O2 partial pressure, toluene is found to dealkylate with a yield of 5.4 ± 1.2% phenol; similarly, m-, o-, and p-xylene dealkylate with yields of 11.2 ± 3.8%, 4.5 ± 3.2%, and 4.3 ± 3.1% cresol, respectively. A dealkylation mechanism via OH-addition in the ipso position is feasible (?H = -9 kcal/mol for phenol formation from toluene) but does not lend itself easily to explain the significant isomer effect observed among xylenes; instead an alternative mechanism is presented that can explain this isomer effect and forms phenol and likely epoxide type products with identical m/z (indistinguishable in our CIMS analysis) via a carbene-type intermediate. Dealkylation adds to the atmospheric production of phenol- and likely epoxide-type products, with aldehydes as expected co-products, and helps improve the carbon balance in the initial stages of aromatic oxidation.

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

2009-08-01

227

rac-2-Phenyl-1-[(2,4,6-triiso-propyl-benzene)-sulfon-yl]aziridine.  

Science.gov (United States)

In the title compound, C23H31NO2S, the geometry of the triiso-propyl-phenyl group is slightly distorted, with elongated C-C bonds at the ipso-C atom, and an S atom which deviates from the benzene ring plane by 0.228?(2)?Å. This distortion is caused by the bulky substituents and, in comparison, an unbent geometry is observed in N-toluene-sulfonyl-aziridine [Zhu et al. (2006 ?). Acta Cryst. E62, o1507-o1508]. ?-? inter-actions between adjacent benzene rings [centroid-centroid distance = 3.7928?(11)?Å] and are observed. PMID:24764875

Golz, Christopher; Preut, Hans; Strohmann, Carsten

2014-02-01

228

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

229

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 70 bar. Typically, 2g of straw and 0.1g of catalyst (66%Ni/SiO2-Al2O3) were dispersed in 15 g 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

230

Benzene vapor recovery and processing  

International Nuclear Information System (INIS)

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

231

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

232

[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

233

ASPEN HYSYS SIMULATION AND COMPARISON BETWEEN ORGANIC SOLVENTS (SULFOLANE AND DMSO) USED FOR BENZENE EXTRACTION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Due to the high increase of the production of aromatic hydrocarbons: benzene, toluene and xylenes BTX from oil because of the large activity of their big markets especially with the availability of great quantities of these aromatic fractions in the oil. This study has two main parts the first presents a general vision of the aromatic hydrocarbons, the second is going to focus on the liquid-liquid extraction with the selected solvents as a separation method. The solvent selection depends on m...

Zaiz, T.; Lanez, H.; Kechida, B.

2013-01-01

234

Hematotoxicity and carcinogenicity of benzene  

Energy Technology Data Exchange (ETDEWEB)

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

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

1989-07-01

235

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

236

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

237

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

Science.gov (United States)

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

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

2009-12-01

238

21 CFR 520.580 - Dichlorophene and toluene capsules.  

Science.gov (United States)

...2010-04-01 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)...

2010-04-01

239

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.)

240

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-02-15

 
 
 
 
241

Carbon doping of MgB2 by toluene and malic-acid-in-toluene  

International Nuclear Information System (INIS)

Research highlights: ? Both toluene and malic acid contribute carbon to MgB2. ? Toluene is more effective than malic acid for transport properties. ? Total carbon can be measured by LECO carbon analysis. - Abstract: The decomposition of malic acid (C4H6O5) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C7H8) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained ?0.4 wt.% C while the toluene/malic acid mixture had ?1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB2 monofilamentary wires established that the toluene/malic acid doped sample had the highest Bc2. However, the toluene-only sample had the highest transport Jc over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.

242

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

243

Ethyl 2-[3-(4-nitrobenzoylthioureido]benzoate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C17H15N3O5S, the nitro and thioureido groups are twisted by 7.2?(7 and 21.4?(2°, respectively, from the nitrobenzene ring plane whereas the thioureido and the ethyl ester group make dihedral angles of 43.0?(1 and 18.0?(2°, respectively, with the benzene rings to which they are attached. Intramolecular N—H...O hydrogen-bonding interactions are observed. In the crystal, intermolecular N—H...O hydrogen bonds connect the molecules into chains running along the a axis.

Sohail Saeed

2010-04-01

244

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

Science.gov (United States)

To select the best available packing material for malodorous organic gases such as toluene and benzene, biofilter performance was compared in biofilters employed different packing materials including porous ceramic (celite), Jeju scoria (lava), a mixture of granular activated carbon (GAC) and celite (GAC/celite), and cubic polyurethane foam (PU). A toluene-degrading bacterium, Stenotrophomonas maltophilia T3-c, was used as the inoculum. The maximum elimination capacities in the celite, lava, and GAC/celite biofilters were 100, 130, and 110 gm(-3) hr(-1), respectively. The elimination capacity for the PU biofilter was approximately 350 g m(-3) hr(-1) at an inlet loading of approximately 430 g m(-3) hr(-1), which was 2 to 3.5 times higher than for the other biofilters. The pressure drop gradually increased in the GAC/ celite, celite and lava biofilters after 23 day due to bacterial over-growth, and the toluene removal efficiency remarkably decreased with increasing pressure drop. Backwashing method was not effective for the control of biomass in these biofilters. In the PU biofilter however, backwashing allowed maintenance of a pressure drop of 1 to 3 mm H2O m(-1) and a removal efficiency of > 80%, indicating that the PU was the best packing material for toluene removal among the packing materials tested. PMID:21047004

Ryu, Hee Wook; Kim, So Jung; Cho, Kyung Suk

2010-05-01

245

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

Science.gov (United States)

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 of benzene, p-xylene, or m-xylene were observed in these initial enrichment cultures. However, m-xylene was degraded by a subculture that was incubated on m-xylene alone. Complete carbon, nitrogen, and electron balances were determined for the degradation of toluene and m-xylene. These balances showed that these compounds were mineralized with greater than 50% conversion to CO2 and significant assimilation into biomass. Additionally, the oxidation of these compounds was shown to be dependent on nitrate reduction and denitrification. These microbial degradative capabilities appear to be widespread, since the widely varied inoculum sources all yielded similar results. PMID:2014990

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

1991-02-01

246

Fuel Dependence of Benzene Pathways  

Energy Technology Data Exchange (ETDEWEB)

The relative importance of formation pathways for benzene, an important precursor to soot formation, was determined from the simulation of 22 premixed flames for a wide range of equivalence ratios (1.0 to 3.06), fuels (C{sub 1}-C{sub 12}), and pressures (20 to 760 torr). The maximum benzene concentrations in 15 out of these flames were well reproduced within 30% of the experimental data. Fuel structural properties were found to be critical for benzene production. Cyclohexanes and C{sub 3} and C{sub 4} fuels were found to be among the most productive in benzene formation; and long-chain normal paraffins produce the least amount of benzene. Other properties, such as equivalence ratio and combustion temperatures, were also found to be important in determining the amount of benzene produced in flames. Reaction pathways for benzene formation were examined critically in four premixed flames of structurally different fuels of acetylene, n-decane, butadiene, and cyclohexane. Reactions involving precursors, such as C{sub 3} and C{sub 4} species, were examined. Combination reactions of C{sub 3} species were identified to be the major benzene formation routes with the exception of the cyclohexane flame, in which benzene is formed exclusively from cascading fuel dehydrogenation via cyclohexene and cyclohexadiene intermediates. Acetylene addition makes a minor contribution to benzene formation, except in the butadiene flame where C{sub 4}H{sub 5} radicals are produced directly from the fuel, and in the n-decane flame where C{sub 4}H{sub 5} radicals are produced from large alkyl radical decomposition and H atom abstraction from the resulting large olefins.

Zhang, H; Eddings, E; Sarofim, A; Westbrook, C

2008-07-14

247

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

248

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

249

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

250

Pollution characteristics and health risk assessment of benzene homologues in ambient air in the northeastern urban area of Beijing, China.  

Science.gov (United States)

Ambient benzene homologues were measured at a site in the northeastern urban area of Beijing, China, from August 24 to September 4, 2012 by SUMMA canister sampling followed by laboratory determination using cryogenic cold trap pre-concentration-GC-MS/FID, and their health risks were also assessed. Daily total benzene homologues ranged from 0.99 to 49.71 microg/m3 with an average of 11.98 microg/m3. Benzene homologues showed higher concentrations in the morning and evening than that at noontime. Comparison with previous studies revealed a trend of decrease for ambient benzene homologues probably due to the effective emission control in Beijing in recent years. Vehicular exhaust was the main source while volatilization of paints and solvents also made substantial contributions. Health risk assessment showed that BTEX (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) and styrene had no appreciable adverse non-cancer health risks for the exposed population, while benzene has potential cancer risk of 1.34E-05. Available data from cities in China all implied that benzene imposes relatively higher cancer risk on the exposed populations and therefore strict control measures should be taken to further lower ambient benzene levels in China. PMID:24649709

Li, Lei; Li, Hong; Zhang, Xinmin; Wang, Li; Xu, Linghong; Wang, Xuezhong; Yu, Yanting; Zhang, Yujie; Cao, Guan

2014-01-01

251

Reactions of 9-Alkyl-3-aminocarbazoles with Ethyl-3-oxo-butanoate and Identification of the Products Obtained  

Directory of Open Access Journals (Sweden)

Full Text Available The reactions in benzene of 9-alkyl-3-aminocarbazoles with ethyl-3-oxobutanoateyielded ethyl-3-[(9-alkyl-9H-carbazol-3-ylamino]but-2-enoate condensation products or N-(9-ethyl-9H-carbazol-3-yl-3-oxobutanamide acylation products. The condensation productswere cyclized to the corresponding 4,7-dihydro-pyrido[2,3-c]-carbazol-1-ones upon heatingin mineral oil at 240-250 °C. The structures of the synthesized compounds were investigatedby IR, mass spectrometry, 1H- and 13C-NMR spectroscopy and MM2 molecular mechanicsand AM1 semi-empirical quantum mechanical methods.

Gema Mikulskiene

2006-01-01

252

40 CFR 442.2 - General definitions.  

Science.gov (United States)

...not limited to: asphalt; benzene; coal tar; crude oil; cutting oil; ethyl benzene...paraffin, and other waxes; tall oil; tar; toluene; xylene; and waste oil. ...wastewaters being discharged to publicly owned treatment works after a facility has...

2010-07-01

253

40 CFR 63.1103 - Source category-specific applicability, definitions, and requirements.  

Science.gov (United States)

...million by volume HAP that...ethylene production unit...million by volume; whichever...following HAP: benzene, cumene, ethyl benzene, hexane...styrene, toluene, o-xylene, m-xylene...Carbon black production...

2010-07-01

254

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

255

40 CFR 63.1103 - Source category-specific applicability, definitions, and requirements.  

Science.gov (United States)

...following HAP: benzene, cumene, ethyl benzene, hexane, naphthalene, styrene, toluene, o-xylene, m-xylene, p-xylene, or 1,3-butadiene (i) Comply with the waste requirements of subpart XX of this part. For ethylene...

2010-07-01

256

Stemofoline ethyl acetate solvate  

Directory of Open Access Journals (Sweden)

Full Text Available Crystals of the title compound, C22H29NO5·C4H8O2, {[systematic name: (2R,3R,5R,5aS,6R,8aR,9S-(5Z-5-[3-butyltetrahydro-6-methyl-2,5-methano-4,3,8a-[1]propanyl[3]ylidenefuro[3,2-f][1,4]oxazepin-7(5H-ylidene]-4-methoxy-3-methylfuran-2(5H-one ethyl acetate solvate} were isolated from the root extracts of Stemona aphylla (Stemonaceae. The structure closely resembles those of stemofoline derivatives which have previously been reported. Intermolecular contacts are observed between some C-bonded H atoms and nearby O atoms, perhaps indicating weak interactions which could influence the packing of species within the unit cell.

Pitchaya Mungkornasawakul

2009-08-01

257

40 CFR 265.1080 - Applicability.  

Science.gov (United States)

...million by volume above background...Chemical Production and Processes...Chemical Production and Processes...Barium; Benzene; Benzotrichloride...Acetate; Ethyl benzene; Ethyl...Thallium; Toluene; Toluene...Warfarin; Xylene; Zinc...polyether production service...the printed volume and on...

2010-07-01

258

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

259

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

International Nuclear Information System (INIS)

f 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.

260

Collision lifetimes of polyatomic molecules at low temperatures: Benzene-benzene vs benzene-rare gas atom collisions.  

Science.gov (United States)

We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom-molecule interaction. We then compare the results of the atom-benzene calculations with those for benzene-benzene collisions. The comparison illustrates that the mean lifetimes of the benzene-benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene-benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene. PMID:25362307

Cui, Jie; Li, Zhiying; Krems, Roman V

2014-10-28

 
 
 
 
261

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

262

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

Science.gov (United States)

Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers. PMID:24623528

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

2014-08-01

263

Reversible toluene adsorption on monolithic carbon aerogels.  

Science.gov (United States)

Thirteen monolithic carbon aerogels with different pore textures were used as toluene adsorbents. Adsorption was carried out under both static and dynamic conditions. Under static conditions at 25 degrees C and at saturation, an adsorption capacity as high as 1.36 cm(3) g(-1) or 1180 mg g(-1) was obtained. Toluene adsorption was a reversible process in all carbon aerogels, and the adsorbed toluene was completely recovered by heating them at 400 degrees C. Regenerated adsorbents showed larger surface area and micropore width than the original samples, indicating that no pore blockage was produced. Adsorption under dynamic conditions at 100 degrees C was also completely reversible after at least three consecutive adsorption-desorption cycles. The ability of these carbon aerogels to reversibly adsorb toluene could be useful for their application in thermal swing adsorption or pressure swing adsorption equipment. PMID:17433536

Maldonado-Hódar, Francisco J; Moreno-Castilla, Carlos; Carrasco-Marín, Francisco; Pérez-Cadenas, Agustín F

2007-09-30

264

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

265

46 CFR Table II to Part 150 - Grouping of Cargoes  

Science.gov (United States)

... Brake fluid base mixtures 1...Cyclopentadiene, Styrene, Benzene mixture Cyclopentene...pyridine copolymer in Toluene Alkylbenzene...Xylene Butyl toluene Cumene Cymene...C10 - C14) benzenes Diethylbenzene...Ethylbenzene Ethyl toluene 1-Hexadecylnaphthalene...solvent mixture Coal tar Coal...

2010-10-01

266

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

Science.gov (United States)

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

Bohnenstiehl, S. D.; Susner, M. A.; Yang, Y.; Collings, E. W.; Sumption, M. D.; Rindfleisch, M. A.; Boone, R.

2011-02-01

267

Major sources of benzene exposure.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Data from EPA's TEAM Study allow us to identify the major sources of exposure to benzene for much of the U.S. population. These sources turn out to be quite different from what had previously been considered the important sources. The most important source of exposure for 50 million smokers is the mainstream smoke from their cigarettes, which accounts for about half of the total population burden of exposure to benzene. Another 20% of nationwide exposure is contributed by various personal act...

Wallace, L. A.

1989-01-01

268

Benzene inhalation by parts washers: new estimates based on measures of occupational exposure to solvent coaromatics.  

Science.gov (United States)

Questions persist regarding assessment of workers' exposures to products containing low levels of benzene, such as mineral spirit solvent (MSS). This study summarizes previously unpublished data for parts-washing activities, and evaluates potential daily and lifetime cumulative benzene exposures incurred by workers who used historical and current formulations of a recycled mineral spirits solvent in manual parts washers. Measured benzene concentrations in historical samples from parts-washing operations were frequently below analytical detection limits. To better assess benzene exposure among these workers, air-to-solvent concentration ratios measured for toluene, ethylbenzene, and xylenes (TEX) were used to predict those for benzene based on a statistical model, conditional on physical-chemical theory supported by new thermodynamic calculations of TEX and benzene activity coefficients in a modeled MSS-type solvent. Using probabilistic methods, the distributions of benzene concentrations were then combined with distributions of other exposure parameters to estimate eight-hour time-weighted average (TWA) exposure concentration distributions and corresponding daily respiratory dose distributions for workers using these solvents in parts washers. The estimated 50th (95th) percentile of the daily respiratory dose and corresponding eight-hour TWA air concentration for workers performing parts washing are 0.079 (0.77) mg and 0.0030 (0.028) parts per million by volume (ppm) for historical solvent, and 0.020 (0.20) mg and 0.00078 (0.0075) ppm for current solvent, respectively. Both 95th percentile eight-hour TWA respiratory exposure estimates for solvent formulations are less than 10% of the current Occupational Safety and Health Administration permissible exposure limit of 1.0 ppm for benzene. PMID:20477986

Sheehan, Patrick; Bogen, Kenneth T; Hicks, Jeffrey; Goswami, Emily; Brorby, Gregory; Lau, Edmund C; Ott, Brian

2010-08-01

269

Aerosol formation and decomposition of dilute benzene derivatives by AC/DC corona discharge  

Energy Technology Data Exchange (ETDEWEB)

The most common treatment methods for removing volatile organic compounds (VOCs) include thermal decomposition, catalytic oxidation, carbon adsorption, destruction in non-thermal plasma (NTP) and condensation. Among these technologies, the use of NTP is gaining considerable attention, particularly AC/DC energized corona plasma systems because of their reliable operation, low cost and high efficiency. One of the ideal NTP based processes is to convert VOCs to environmentally sound compounds, such as water. However, since the plasma-initialed reactions are difficult to control, some undesirable products such as aerosols are often observed from VOC removal. The formation of aerosol must therefore be considered in structure-dependent VOC removal characteristics. This study examined the decomposition of three benzene derivatives by novel AC/DC corona discharge with a closed loop flow system in air. The experiments focused primarily on aerosol formation and the individual removal efficiency of benzene, toluene and styrene. The removal process of styrene, benzene and toluene were found to be different from each other because of their different reactivity with radicals. The generated radicals of styrene were efficiently used for the removal process, but the generated radicals of benzene and toluene were mainly quenched by bulk gases. The study showed that a large concentration of aerosols can be generated in humid air. The generated aerosols can be collected by electrostatic precipitation in the AC/DC energized plasma system. It was concluded that the chemical structure is one of most important factors that influence the removal process of VOCs for non-thermal plasma processing. 17 refs., 7 figs.

Zhang, X.; Chen, W.; Zhu, J.; Feng, W.; Yan, K. [Zhejiang Univ., Hangzhou (China). Industrial Ecology and Environment Research Inst.

2010-07-01

270

Mechanism of thermal toluene autoxidation.  

Science.gov (United States)

Aerobic oxidation of toluene (PhCH3) is investigated by complementary experimental and theoretical methodologies. Whereas the reaction of the chain-carrying benzylperoxyl radicals with the substrate produces predominantly benzyl hydroperoxide, benzyl alcohol and benzaldehyde originate mainly from subsequent propagation of the hydroperoxide product. Nevertheless, a significant fraction of benzaldehyde is also produced in primary PhCH3 propagation, presumably via proton rather than hydrogen transfer. An equimolar amount of benzyl alcohol, together with benzoic acid, is additionally produced in the tertiary propagation of PhCHO with benzylperoxyl radicals. The "hot" oxy radicals generated in this step can also abstract aromatic hydrogen atoms from PhCH3, and this results in production of cresols, known inhibitors of radical-chain reactions. The very fast benzyl peroxyl-initiated co-oxidation of benzyl alcohol generates HO2* radicals, along with benzaldehyde. This reaction also causes a decrease in the overall oxidation rate, due to the fast chain-terminating reaction of HO2*with the benzylperoxyl radicals, which causes a loss of chain carriers. Moreover, due to the fast equilibrium PhCH2OOH+HO2* right harpoon over left harpoonPhCH2OO* + H2O2, and the much lower reactivity of H2O2 compared to PhCH2OOH, the fast co-oxidation of the alcohol means that HO2* gradually takes over the role of benzylperoxyl as principal chain carrier. This drastically changes the autoxidation mechanism and, among other things, causes a sharp decrease in the hydroperoxide yield. PMID:18061915

Hermans, Ive; Peeters, Jozef; Vereecken, Luc; Jacobs, Pierre A

2007-12-21

271

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

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C15H18O4S, was prepared by the oxidation of ethyl 2-(3-ethylsulfanyl-5-methyl-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 = 3.655?(3?Å] and by three intermolecular C—H...O non-classical hydrogen bonds.

Hong Dae Choi

2009-04-01

272

Ethyl 6-(4-ethoxyphenyl-4-(furan-2-yl-2-oxocyclohex-3-ene-1-carboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C21H22O5, was prepared by NaOH-catalysed cyclocondensation of 3-(4-ethoxyphenyl-1-(furan-2-ylprop-2-en-1-one with ethyl acetoacetate. In the crystal, C—H...O and C—H...? interactions link the molecules. In the title molecule, the furan and cyclohexene rings are almost parallel [6.77?(11°] and the cyclohexene ring is approximately perpendicular to the benzene ring [84.79?(5°].

Amir Badshah

2009-01-01

273

Molecular Structure of Ethyl maltol  

Science.gov (United States)

Ethyl maltol was discovered in the 1970s. It was originally isolated from larch tree bark and is produced through fermentation-organic synthesis. Ethyl maltol occurs naturally in cereal, bread crust, coffee, and cocoa. This substance is also used as a flavor enhancer because it tends to mask bad tasting chemicals, and heightens richness and creaminess. The compound has been employed as a flavor enhancer in wine, chocolate, vanilla, fruit flavored drinks, pastries, candy, tobacco, cosmetics, and medicines.

2002-10-11

274

Shear Viscosity of Benzene, Toluene, and p-Xylene by Non-equilibrium Molecular Dynamics Simulations  

International Nuclear Information System (INIS)

Green and Kubo showed that the phenomenological coefficients describing many transport processes and time dependent phenomena in general could be written as integrals over a certain type of function called a time correlation function. The Green-Kubo formulas are the formal expressions for hydrodynamic field variables and some of the thermodynamic properties in terms of the microscopic variables of an N-particle system. The identification of microscopic expressions for macroscopic variables is made by a process of comparison of the conservation equations of hydrodynamics with the microscopic equations of change for conserved densities. The importance of these formulas is three-fold: they provide an obvious method for calculating transport coefficients using computer simulation, a convenient starting point for constructing analytic theories for non-equilibrium processes, and an essential information for designing non-equilibrium molecular dynamics (NEMD) algorithm.

275

Confinement of molecular liquids: consequences on thermodynamic, static and dynamical properties of benzene and toluene.  

Science.gov (United States)

We relate the dynamical behavior of molecular liquids confined in mesoscopic cylindrical pores to the thermodynamic properties, heat capacity and density and to the static structure by combining different experimental methods (H-NMR, calorimetry, elastic and inelastic neutron scattering, numerical simulations). The crystallization process is greatly reduced or avoided by confinement under standard cooling conditions, instead a glass transition temperature T(g) at the 1000s time scale can be observed. The pore averaged local structure of the confined liquid is not noticeably affected when "excluded-volume" corrections are carefully applied, but follows the density changes reflected by the Bragg peak intensities of the porous matrices. The pore size dependence of T(g) is dominated by two factors, surface interaction and finite-size effect. For the smallest pores ([Formula: see text], [Formula: see text] being the van der Waals radius of a molecule), one observes an increase of T(g) and a broadening of the transition region, related to the interaction with the surface that induces a slowing-down of the molecules close to the wall. This is confirmed by neutron scattering experiments and molecular-dynamics simulations at shorter time scales and higher temperatures, which indicate a remaining fraction of frozen molecules. For larger pore sizes, taking the decrease of density under confinement conditions into account, a decrease of T(g) is observed. This could be related to finite-size effects onto the putative cooperativity length that is often invoked to explain glass formation. However, no quantitative determination of this length (not to mention its T-dependence) can be extracted, since the interaction with the wall itself introduces an additional length that adds to the complexity of the problem. PMID:15007675

Alba-Simionesco, C; Dosseh, G; Dumont, E; Frick, B; Geil, B; Morineau, D; Teboul, V; Xia, Y

2003-09-01

276

(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

277

Evaluation of genotoxic effects of benzene and its derivatives in workers of gas stations.  

Science.gov (United States)

The search for reliable biomarkers of human exposure to benzene and its derivatives is still subject of research. Many of the proposed biomarkers have limitations ranging from the low sensitivity to the wide variability of results. Thus, the aim of our study was to assess the frequencies of chromosomal abnormalities (CA) and sister chromatid exchanges (SCE) in workers of gas stations, with (cases, n?=?19) and without (local controls, n?=?6) risk of exposure to benzene and its derivatives, comparing them with the results from the general population (external controls, n?=?38). The blood dosages of benzene, toluene, and xylenes were measured in all participants. Blood solvent levels were compared with the findings obtained in cytogenetic evaluation and a research protocol which included data of the workplace, lifestyle, and health of the individuals. We did not detect the presence of benzene and its derivatives and did not find chromosomal damage that may be associated with the gas station activity in cases. Moreover, although we found an association of increased SCE and the working time in the local controls, the values found for SCE are within normal limits. Thus, our evaluation of SCE and CA reflected the levels of benzene and its derivatives observed in the blood. We believe, therefore, that SCE and CA may actually constitute possible tests for the evaluation of these exposures. However, we believe that further studies, including individuals at risk, are important to confirm this assertion. PMID:24292950

Trevisan, Patrícia; da Silva, Juliane Nascimento; da Silva, Alessandra Pawelec; Rosa, Rafael Fabiano Machado; Paskulin, Giorgio Adriano; Thiesen, Flávia Valladão; de Oliveira, Ceres Andréia Vieira; Zen, Paulo Ricardo Gazzola

2014-04-01

278

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

279

Inhibition of pure cultures of methanogens by benzene ring compounds  

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-10-01

280

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

 
 
 
 
281

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...following legend: DANGER BENZENE CANCER HAZARD FLAMMABLE—NO SMOKING AUTHORIZED...legend: DANGER CONTAINS BENZENE CANCER HAZARD (2) Material safety data sheets...tubes should be capped with the supplied plastic caps immediately after sampling....

2010-07-01

282

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...employee's use of protective clothing or equipment and respirators... DANGER BENZENE CANCER HAZARD FLAMMABLE...personal protective clothing and equipment are required...wear the protective clothing and equipment. VII...Benzene I. Physical and Chemical Data A....

2010-07-01

283

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...removal. (j) Communication of benzene hazards...OSHA's Hazard Communication Standard, 29 CFR...D) The name, social security number...in which benzene affects your health. ...Extinguishing Media: Carbon dioxide...concentrations can affect central...

2010-07-01

284

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

... (1 ) Past work exposure to benzene...outside of the current work situation. ...signs which may be related to benzene exposure...relating to blood disorders: (B) A complete...employee's medical and work history related to exposure to...

2010-07-01

285

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Systemic absorption may cause depression of the hematopoietic...liquid benzene immediately causes pulmonary edema and...contact with benzene may cause erythema. Repeated...followed by a period of depression, drowsiness, or...

2010-07-01

286

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...physical signs relating to blood disorders: (B) A complete blood...Systemic absorption may cause depression of the hematopoietic system...liquid benzene immediately causes pulmonary edema and hemorrhage...Exposure to benzene may cause an early rise in serum...

2010-07-01

287

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

International Nuclear Information System (INIS)

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

288

Anaerobic Benzene Oxidation by Geobacter Species  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzen...

Zhang, Tian; Bain, Timothy S.; Nevin, Kelly P.; Barlett, Melissa A.; Lovley, Derek R.

2012-01-01

289

Role of delocalization in benzene  

Energy Technology Data Exchange (ETDEWEB)

The influence of [pi] delocalization on the geometry of benzene is examined at the ab initio SCF level of theory. We find that benzene favors a bond alternating geometry when its canonical [pi] MOs are replaced by three localized ethylenic orbitals, revealing that delocalization is in part responsible for the equilibrium symmetric structure. In apparent contrast, a [sigma]-[pi] energy partitioning analysis suggests that the benzene [sigma] framework is responsible for the symmetric structure, the [pi] system preferring a distorted geometry. Shaik et al. have therefore concluded that delocalization in not an important symmetrizing force in this molecule. We show, however, that the [pi] energy component contains a sizable and strongly geometry dependent contribution from the localized (Kekule) wave function. Thus, it appears to be misleading to judge the nature of delocalization based on a [sigma]-[pi] partition. We conclude that delocalization effects act to strongly stabilize symmetric benzene in essential accord with the concepts of classical resonance theory. 27 refs., 6 figs., 2 tabs.

Glendening, E.D.; Faust, R.; Streitwieser, A.; Vollhardt, K.P.C. (Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States)); Weinbold, F. (Univ. of Wisconsin, Madison, WI (United States))

1993-11-17

290

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

291

Atmospheric chemistry of ethyl propionate.  

Science.gov (United States)

Ethyl propionate is a model for fatty acid ethyl esters used as first-generation biodiesel. The atmospheric chemistry of ethyl propionate was investigated at 980 mbar total pressure. Relative rate measurements in 980 mbar N(2) at 293 ± 0.5 K were used to determine rate constants of k(C(2)H(5)C(O)OC(2)H(5) + Cl) = (3.11 ± 0.35) × 10(-11), k(CH(3)CHClC(O)OC(2)H(5) + Cl) = (7.43 ± 0.83) × 10(-12), and k(C(2)H(5)C(O)OC(2)H(5) + OH) = (2.14 ± 0.21) × 10(-12) cm(3) molecule(-1) s(-1). At 273-313 K, a negative Arrhenius activation energy of -3 kJ mol(-1) is observed.. The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar N(2) gave the following products (stoichiometric yields): ClCH(2)CH(2)C(O)OC(2)H(5) (0.204 ± 0.031), CH(3)CHClC(O)OC(2)H(5) (0.251 ± 0.040), and C(2)H(5)C(O)OCHClCH(3) (0.481 ± 0.088). The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar of N(2)/O(2) (with and without NO(x)) gave the following products: ethyl pyruvate (CH(3)C(O)C(O)OC(2)H(5)), propionic acid (C(2)H(5)C(O)OH), formaldehyde (HCHO), and, in the presence of NO(x), PAN (CH(3)C(O)OONO(2)). The lack of acetaldehyde as a product suggests that the CH(3)CH(O)C(O)OC(2)H(5) radical favors isomerization over decomposition. From the observed product yields, we conclude that H-abstraction by chlorine atoms from ethyl propionate occurs 20.4 ± 3.1%, 25.1 ± 4.0%, and 48.1 ± 8.8% from the CH(3)-, -CH(2)-, and -OCH(2)- groups, respectively. The rate constant and branching ratios for the reaction between ethyl propionate and the OH radical were investigated theoretically using quantum mechanical calculations and transition state theory. The stationary points along the reaction path were optimized using the CCSD(T)-F12/VDZ-F12//BH&HLYP/aug-cc-pVTZ level of theory; this model showed that OH radicals abstract hydrogen atoms primarily from the -OCH(2)- group (80%). PMID:22524192

Andersen, Vibeke F; Ørnsø, Kristian B; Jørgensen, Solvejg; Nielsen, Ole John; Johnson, Matthew S

2012-05-31

292

ATMOSPHERIC BENZENE DEPLETION BY SOIL MICROORGANISMS  

Science.gov (United States)

Gaseous benzene was rapidly depleted in exposure chambers containing viable soils and plants. When separate components of the system were analyzed, no benzene was detected in soils, plants, or water. Soil microorganisms were shown to be responsible for metabolizing benzene, yield...

293

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

Scientific Electronic Library Online (English)

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

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

2012-01-01

294

Effect of solvents on the radiation-induced polymerization of ethyl and isopropyl vinyl ethers  

International Nuclear Information System (INIS)

The effect of solvents on the radiation-induced cationic polymerization of ethyl and isopropyl vinyl ethers (EVE and IPVE, respectively) was investigated. EVE and IPVE polymerizations were carried out in bulk and in solution under superdry conditions in which polar impurities, especially water, have been reduced to negligible levels. This was accomplished by means of a sodium mirror technique using joint free baked out glass equipment and high vacuum. Plots of the monomer conversions and irradiation times were obtained for EVE and IPVE polymerizations in bulk and in benzene solution at constant monomer concentrations. The monomer concentration dependence of the polymerization rate was studied for EVE polymerization in bulk and in benzene, diethlyl ether, diglyme and methylene chloride, and for IPVE polymerization in bulk and in benzene. Solvent effect on the estimated propagating rate constants was examined for EVE and IPVE polymerization in bulk and in solution. The effect of temperature on the polymerization rate was also investigated for EVE polymerization in bulk ad in benzene, diethyl and diisopropyl ethers, methylene chloride and nitromethane, and for IPVE ploymerization in bulk and in benzene

295

Molecular Structure of Ethyl cyclotene  

Science.gov (United States)

Ethyl Cyclotene has a similar odor and flavor to Cyclotene. It is naturally found in coffee and tobacco. As a food additive, this compound has a very strong maple odor and taste. It contributes to the fragrance of rum and whiskey.

2006-09-18

296

Ethyl 3-[2-(p-tolylcarbamothioylhydrazinylidene]butanoate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C14H19N3O2S, was obtained from a condensation reaction of N-(p-tolylhydrazinecarbothioamide and ethyl acetoacetate. The molecule assumes an E configuration; the thiosemicarbazide and ester groups are located on the opposite sides of the C=N bond. The almost planar thiosemicarbazide unit (r.m.s. deviation = 0.0130?Å is tilted at a dihedral angle of 49.54?(12° with respect to the benzene ring. Intermolecular N—H...N and N—H...S hydrogen bonding stabilizes the crystal structure. The ethoxy group of the ester unit is disordered over two positions, with a site-occupancy ratio of 0.680?(10:0.320?(10.

Yan-Ling Zhang

2010-11-01

297

Volumetric, Viscometric, Ultrasonic, and Refractive Index Properties of Liquid Mixtures of Benzene with Industrially Important Monomers at Different Temperatures  

Science.gov (United States)

The densities, ?, viscosities, ?, ultrasonic speeds, u, and refractive indices, n D, of pure benzene, methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), styrene (STY), and their binary liquid mixtures have been measured over the entire composition range at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. The experimental data have been used to calculate excess molar volumes. Partial molar volumes of MA/EA/BA/STY in benzene at infinite dilution and at different temperatures have also been evaluated. The results were discussed in terms of molecular interactions prevailing in the mixtures.

Ali, A.; Nabi, F.; Tariq, M.

2009-04-01

298

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

Directory of Open Access Journals (Sweden)

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

P .Nassiri; F. Golbabai; A. Barzegar

1996-08-01

299

Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium trifluoroacetate.  

Science.gov (United States)

The activity coefficients at infinite dilution, gamma13(infinity) for 29 solutes, alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols and water in the ionic liquid 1-ethyl-3-methylimidazolium trifluoroacetate ([EMIM][TFA]), were determined by gas-liquid chromatography at temperatures from 298.15-368.15 K. The partial molar excess enthalpies at infinite dilution DeltaH1(E,infinity) values were calculated from the experimental gamma13(infinity) values obtained over the temperature range. The selectivities for the hexane/benzene and cyclohexane/benzene separation were calculated from gamma13(infinity) and compared to the literature values for other ionic liquids, NMP and sulfolane. PMID:17887791

Doma?ska, Urszula; Marciniak, Andrzej

2007-10-18

300

21 CFR 573.420 - Ethyl cellulose.  

Science.gov (United States)

...RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following...

2010-04-01

 
 
 
 
301

27 CFR 21.108 - Ethyl ether.  

Science.gov (United States)

...Firearms 1 2010-04-01 2010-04-01 false Ethyl ether. 21.108 Section 21.108 Alcohol, Tobacco Products...AND RUM Specifications for Denaturants § 21.108 Ethyl ether. (a) Odor. Characteristic odor. (b) Specific...

2010-04-01

302

Ethyl 2-[1-(3-methylbutyl-4-phenyl-1H-1,2,3-triazol-5-yl]-2-oxoacetate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C17H21N3O3, the non-planar (r.m.s. deviation = 0.212?Å ethyl (oxoacetate group is oriented towards the phenyl substituent. The triazole and benzene rings are twisted with respect to each other, making a dihedral angle of 41.69?(6°. In the crystal, molecules are arranged into centrosymmetric R22(10 dimers via pairs of C—H...O interactions involving the ethyl (oxoacetate groups. In addition, the triazole rings show ?–? stacking interactions, with their centroids at a distance of 3.745?(2?Å.

Muhammad Hafeez

2013-12-01

303

Determination of benzene and associated volatile compounds in mainstream cigarette smoke.  

Science.gov (United States)

There is continuing interest, by health professionals and individuals, in the composition of mainstream tobacco smoke. Regular official surveys of tar, nicotine and carbon monoxide yields are from time to time supplemented by special surveys of specific components. In this study, gas chromatography-mass spectrometry was used to identify and quantify benzene and certain other volatile compounds of interest in the mainstream smoke of 26 cigarette brands on the UK market and of smoke from hand rolled tobacco. Validation of the method adopted demonstrated the ability to identify and to measure reliably the yields of benzene and seven other compounds: toluene, ethylbenzene, m/p-xylene, o-xylene, styrene, isoprene and acrylonitrile. Yields of these analytes were ranked and compared with the tar yields of the brands. In general terms, brands yielding 3 mg of tar per cigarette. For many of the higher tar brands the yield of vapour phase analyte was approximately proportional to the tar yield. Smoking cigarettes with an average yield of 50 micron of benzene per cigarette has been compared with the occupational maximum exposure limit (16 mg m-3) concentration and with US studies on the home environment. Smoking the majority of brands examined could contribute significantly to the population exposure of benzene and the other volatile organic compounds considered in this study. PMID:9709493

Darrall, K G; Figgins, J A; Brown, R D; Phillips, G F

1998-05-01

304

21 CFR 172.868 - Ethyl cellulose.  

Science.gov (United States)

...2010-04-01 2009-04-01 true 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...

2010-04-01

305

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

306

Intermolecular interactions in solid benzene.  

Science.gov (United States)

The lattice dynamics and molecular vibrations of benzene and deuterated benzene crystals are calculated from force constants derived from density-functional theory (DFT) calculations and compared with measured inelastic neutron-scattering spectra. A very small change (0.5%) in lattice parameter is required to obtain real lattice-mode frequencies across the Brillouin zone. There is a strong coupling between wagging and breathing modes away from the zone center. This coupling and sensitivity to cell size arises from two basic interactions. Firstly, comparatively strong interactions that hold the benzene molecules together in layers. These include an intermolecular interaction in which H atoms of one molecule link to the center of the aromatic ring of a neighboring molecule. The layers are held to each other by weaker interactions, which also have components that hold molecules together within a layer. Small changes in the lattice parameters change this second type of interaction and account for the changes to the lattice dynamics. The calculations also reveal a small auxetic effect in that elongation of the crystal along the b axis leads to an increase in internal pressure in the ac plane, that is, elongation in the b direction induces expansion in the a and c directions. PMID:16460192

Kearley, G J; Johnson, M R; Tomkinson, J

2006-01-28

307

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

308

Measurements of alveolar concentrations of toluene.  

Science.gov (United States)

The use of a photoionisationdetector (PID) for measurement of alveolar concentrations of gases and vapours was evaluated during a human exposure experiment with toluene. Two other methods, the standard gaspipette method and the gasbag /charcoal method, was tested for comparison. The best method appeared to be the PID-method. The major disadvantage in using this instrument was the missing selectivity towards individual compounds in a mixed atmosphere. In all other respects, the method is just as good as or better than the standard gaspipette method and the gasbag method. Results from 40 measurements with the three methods on 16 persons were examined statistically, and the average toluene absorption at 100 ppm exposure levels was estimated to be 1.6 mg/min. PMID:6724703

Mølhave, L; Pedersen, O F

1984-01-01

309

Radiolysis of ferric hexafluoroacetoacetylacetonate-toluene solutions  

International Nuclear Information System (INIS)

Ferric hexafluoroacetylacetonate was used to determine the yield of radicals captured in the gamma radiolysis of air-free toluene at 27 deg C. The G value for disappearance of the ferric chelate by radical capture and for the resulting formation of inert ferrous hexafluoroacetylacetonate is 1.05 molecules/eV. The chelates were determined spectrophotimetrically. No hexafluoroacetylacetone was formed. Radicals that are scavenged are the methyl radical and an unknown radical which is capable of combining with the benzyl radical. The effect of ferric chelate is therefore actually to increase the yield of bibenzyl. Activation energies are calculated. Experiments on flash photolysis indicated that the ferric chelate does not react with excited toluene molecules. (N.D.H.)

310

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

311

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

312

Human response to varying concentrations of toluene  

DEFF Research Database (Denmark)

Thirty two males and 39 females aged 31-50 were exposed for 7 h to one of the three following conditions: (1) Clean air, (2) constant exposure to 100 ppm toluene, or (3) a varying exposure with the same time-weighted average, but with peaks of 300 ppm every 30 min. During exposure the subjects exercised in three 15-min periods with a load of 50 to 100 W. Exposure to toluene caused significant (P less than 0.05) complaints about poor air quality, altered temperature and noise perception, increased irritation in the nose and the lower airways, feeling of intoxication, and there were tendencies (P less than 0.1) towards irritation in the throat, headache and dizziness. In the four performance tests there was a tendency towards a lower score in a vigilance test while no effect of toluene exposure was seen in a peg board test, a five choice serial reaction test, or a colour test, indicating only minimal if any effect on the psychomotor or visual performance. There was no difference in the acute effects caused by the exposure containing peak concentrations and by the constant exposure.

Bælum, Jesper; Lundqvist, G R

1990-01-01

313

Ethyl 4-butylamino-3-nitrobenzoate  

Directory of Open Access Journals (Sweden)

Full Text Available In the crystal structure of the title compound, C13H18N2O4, the asymmetric unit consists of three crystallographically independent ethyl 4-butylamino-3-nitrobenzoate molecules. There is an intramolecular N—H...O hydrogen bond in each molecule, which generates an S(6 ring motif. The structure is stabilized by intermolecular N—H...O and C—H...O hydrogen bonds.

Shivanagere Nagojappa Narendra Babu

2009-09-01

314

40 CFR 261.31 - Hazardous wastes from non-specific sources.  

Science.gov (United States)

...or more (by volume) of one or...or more (by volume) of one or...non-halogenated solvents: Xylene, acetone, ethyl acetate, ethyl benzene, ethyl ether...or more (by volume) of one or...non-halogenated solvents: Toluene, methyl ethyl...purification) from the production or...

2010-07-01

315

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

316

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.

1989-01-01

317

Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei  

Energy Technology Data Exchange (ETDEWEB)

Metabolism of benzene is thought to be necessary to produce the toxic effects, including carcinogenicity, associated with benzene exposure. To extrapolate from the results of rodent studies to potential health risks in man, one must know how benzene metabolism is affected by species, dose, dose rate, and repeated versus single exposures. The purpose of our studies was to determine the effect of repeated inhalation exposures on the metabolism of (14C)benzene by rodents. Benzene metabolism was assessed by characterizing and quantitating urinary metabolites, and by quantitating 14C bound to hemoglobin and micronuclei induction. F344/N rats and B6C3F1 mice were exposed, nose-only, to 600 ppm benzene or to air (control) for 6 hr/day, 5 days/week for 3 weeks. On the last day, both benzene-pretreated and control animals were exposed to 600 ppm, 14C-labeled benzene for 6 hr. Individual benzene metabolites in urine collected for 24 hr after the exposure were analyzed. There was a significant decrease in the respiratory rate of mice (but not rats) pretreated with benzene which resulted in lower levels of urinary (14C)benzene metabolites. The analyses indicated that the only effects of benzene pretreatment on the metabolite profile in rat or mouse urine were a slight shift from glucuronidation to sulfation in mice and a shift from sulfation to glucuronidation in rats. Benzene pretreatment also had no effect, in either species, on formation of (14C)benzene-derived hemoglobin adducts. Mice and rats had similar levels of hemoglobin adduct binding, despite the higher metabolism of benzene by mice. This indicates that hemoglobin adduct formation occurs with higher efficiency in rats. After 1 week of exposure to 600 ppm benzene, the frequency of micronucleated, polychromatic erythrocytes (PCEs) in mice was significantly increased.

Sabourin, P.J.; Sun, J.D.; MacGregor, J.T.; Wehr, C.M.; Birnbaum, L.S.; Lucier, G.; Henderson, R.F. (Inhalation Toxicology Research Institute, Albuquerque, NM (USA))

1990-05-01

318

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

Directory of Open Access Journals (Sweden)

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

Shan-Heng Wang

2008-08-01

319

Analysis and evaluation of trans,trans-muconic acid as a biomarker for benzene exposure.  

Science.gov (United States)

Benzene is an important industrial chemical and, due to its occurrence in mineral oil and its formation in many combustion processes, a widespread environmental pollutant. Since benzene is hematoxic and has been classified as a human carcinogen, monitoring and control of benzene exposure is of importance. Although trans,trans-muconic acid (ttMA) was identified as a urinary metabolite of benzene at the beginning of this century, only recently has its application as a biomarker for occupational and environmental benzene exposure been investigated. The range of metabolic conversion of benzene to ttMA is about 2-25% and dependent on the benzene exposure level, simultaneous exposure to toluene, and probably also to genetic factors. For the quantitation of ttMA in urine, HPLC methods using UV and diode array detection as well as GC methods combined with MS or FID detection have been described. Sample pretreatment for both HPLC and GC analysis comprises centrifugation and enrichment by solid-phase extraction on anion-exchange sorbents. Described derivatization procedures prior to GC analysis include reaction with N,O-bis(trimethysilyl)acetamide, N,O-bis(trimethylsilyl)trifluoroacetamide, pentafluorobenzyl bromide and borontrifluoride-methanol. Reported limits of detection for HPLC methods range from 0.1 to 0.003 mg l(-1), whereas those reported for GC methods are 0.03-0.01 mg l(-1). Due to its higher specificity, GC methods appear to be more suitable for determination of low urinary ttMA levels caused by environmental exposure to benzene. In studies with occupational exposure to benzene (>0.1 ppm), good correlations between urinary ttMA excretion and benzene levels in breathing air are observed. From the reported regressions for these variables, mean excretion rates of ttMA of 1.9 mg g(-1) creatinine or 2.5 mg l(-1) at an exposure dose of 1 ppm over 8 h can be calculated. The smoking-related increase in urinary ttMA excretion reported in twelve studies ranged from 0.022 to 0.2 mg g(-1) creatinine. Only a few studies have investigated the effect of exposure to environmental levels of benzene (<0.01 ppm) on urinary ttMA excretion. A trend for slightly increased ttMA levels in subjects living in areas with high automobile traffic density was observed, whereas exposure to environmental tobacco smoke did not significantly increase the urinary ttMA excretion. It is concluded that urinary ttMA is a suitable biomarker for benzene exposure at occupational levels as low as 0.1 ppm. Biomonitoring of exposure to environmental benzene levels (<0.01 ppm) using urinary ttMA appears to be possible only if the ingestion of dietary sorbic acid, another precursor to urinary ttMA, is taken into account. PMID:9832246

Scherer, G; Renner, T; Meger, M

1998-10-01

320

Solution scattering studies of the hierarchical assembly of porphyrin trimers based on benzene triscarboxamide.  

Science.gov (United States)

The self-assembly of achiral and chiral porphyrin trimers based on benzene triscarboxamide in solution is studied with the help of NMR, FT-IR, UV-vis, and CD spectroscopy. These studies revealed that in apolar solvents the porphyrin trimers self-assembled in columnar stacks via a combination of hydrogen bonding and ?-? stacking interactions. While the critical aggregation constant is about 0.2 mM in chloroform, aggregation already occurs at micromolar concentrations in n-hexane. Small angle neutron scattering (SANS) studies in chloroform, toluene, and n-hexane confirmed aggregation of the trimers into columnar stacks. In chloroform and n-hexane, but not in toluene, the trimers gelated the solvent. In chloroform the stacks of the achiral trimer were found to contain on average about 70 molecules, while in toluene the stacks were much smaller and contained on average 7-9 molecules. In n-hexane the SANS studies revealed that the chiral trimer formed a gel with an average mesh size of the transient network of chains of approximately 90 nm, with chains being built up from effective cylindrical aggregates with an average length of 20 nm. PMID:25363515

van Hameren, Richard; van Buul, Arend M; Visser, Dirk; Heenan, Richard K; King, Stephen M; Rowan, Alan E; Nolte, Roeland J M; Pyckhout-Hintzen, Wim; Elemans, Johannes A A W; Feiters, Martin C

2014-11-19

 
 
 
 
321

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

Science.gov (United States)

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

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

2012-11-01

322

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

323

Somatosensory evoked potentials in workers exposed to toluene and styrene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Somatosensory evoked potentials (SEPs) were used to evaluate possible subclinical impairment of the nervous system due to occupational exposure to toluene and styrene. A group of 36 rotogravure printers with severe exposure to toluene, 20 workers with severe exposure to styrene in a glass laminate manufacturing plant, and a comparison group of healthy subjects were studied. The severity of exposure was documented by measurements of toluene and styrene concentrations in breathing zone air, by ...

Ste?tka?rova?, I.; Urban, P.; Procha?zka, B.; Luka?s, E.

1993-01-01

324

Anaerobic benzene oxidation by Geobacter species.  

Science.gov (United States)

The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 10(9) and 8.4 × 10(9) cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 10(9) cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. PMID:23001648

Zhang, Tian; Bain, Timothy S; Nevin, Kelly P; Barlett, Melissa A; Lovley, Derek R

2012-12-01

325

Mechanistic considerations in benzene physiological model development  

Energy Technology Data Exchange (ETDEWEB)

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Because benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol, and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus the potential exists for competition among various enzymes for phenol. Zonal localization of phase I and phase 11 enzymes in various regions of the liver acinus also impacts this competition. Biologically based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans. 39 refs., 4 figs., 2 tabs.

Medinsky, M.A.; Kenyon, E.M.; Seaton, M.J.; Schlosser, P.M. [Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)

1996-12-01

326

Anaerobic benzene oxidation by Geobacter species  

DEFF Research Database (Denmark)

The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 109 and 8.4 × 109 cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 109 cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. © 2012, American Society for Microbiology.

Zhang, Tian; Bain, Timothy S.

2012-01-01

327

Excess parameter studies on the binary mixtures of toluene with ketones at different temperatures  

International Nuclear Information System (INIS)

Density, ?, ultrasonic speed, u, and viscosity, ? of binary mixtures of toluene with acetone (AC), ethyl methyl ketone (EMK), and acetophenone (AP), including those of pure liquids are measured over the entire composition range at temperatures (298.15, 303.15, and 308.15) K respectively. From these experimental results, deviations in isentropic compressibility, ?ks and ultrasonic speed, ?u, excess intermolecular free length, LfE, excess Gibbs free energy of activation, ?G*E, partial molar volumes (V-barm,10,V-barm,20,V-bar?,10,V-bar?,20) partial molar compressibilities (K-barm,10,K-barm,20,K-bar?,10, and K-bar?,20) and their excess values (V-barm,10E,V-barm,20E,V-bar?,10E,V-bar?,20E,K-barm,10E,K-barm,20E, K-bar?,10E, and K-bar?,20E) of the components at infinite dilution are calculated. The values of ?ks and LfE are found to be negative, and those of ?u and ?G*E are found to be positive, indicating the presence of specific interactions between toluene and ketone molecules and the interactions follow the order: AC > EMK >llow the order: AC > EMK > AP.

328

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

329

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

330

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

331

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

International Nuclear Information System (INIS)

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)

332

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

333

Ethyl 1-(butan-2-yl-2-(2-methoxyphenyl-1H-benzimidazole-5-carboxylate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C21H24N2O3, the mean planes of the benzene ring and the benzimidazole ring system form a dihedral angle of 69.94?(7°. The ethyl group atoms of the ethanoate fragment are disordered over two sets of sites, with refined occupancies of 0.742?(6 and 0.258?(6. In the crystal, there are weak C—H...N hydrogen bonds which connect molecules into chains along the b axis. A weak intermolecular C—H...? interaction is also observed.

Natarajan Arumugam

2011-12-01

334

Ethyl 1-(butan-2-yl)-2-(2-methoxyphenyl)-1H-benzimidazole-5-carboxylate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C21H24N2O3, the mean planes of the benzene ring and the benzimidazole ring system form a dihedral angle of 69.94?(7)°. The ethyl group atoms of the ethanoate fragment are disordered over two sets of sites, with refined occupancies of 0.742?(6) and 0.258?(6). In the crystal, there are weak C—H...N hydrogen bonds which connect molecules into chains along the b axis. A weak intermolecular C—H...? interacti...

Natarajan Arumugam; Nurziana Ngah; Hasnah Osman; Aisyah Saad Abdul Rahim

2011-01-01

335

Ethyl 1-sec-butyl-2-(4-chlorophenyl)-1H-benzimidazole-5-carboxylate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C20H21ClN2O2, the ethyl 1H-benzimidazole-5-carboxylate ring system, excluding the methylene and methyl H atoms, is almost planar, with a maximum deviation of 0.055?(1)?Å, and makes a dihedral angle of 40.63?(4)° with the benzene ring. The sec-butyl group is disordered over two positions, with refined site occupancies of 0.855?(4) and 0.145?(4). In the crystal, molecules are linked into chains along [010...

Natarajan Arumugam; Aisyah Saad Abdul Rahim; Hasnah Osman; Ching Kheng Quah; Hoong-Kun Fun

2010-01-01

336

Ethyl 1-phenyl-2-[4-(trifluoromethoxy)phenyl]-1H-benzimidazole-5-carboxylate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C23H17F3N2O3, an intramolecular C—H...F hydrogen bond generates an S(6) ring motif. The essentially planar 1H-benzimidazole ring system [maximum deviation = 0.021?(2)?Å] forms dihedral angles of 25.00?(10) and 62.53?(11)° with the trifluoromethoxy-substituted benzene and phenyl rings, respectively. The twist of the ethyl acetate group from the least-squares plane of the 1H-benzimidazole ring system is d...

Yeong Keng Yoon; Mohamed Ashraf Ali; Tan Soo Choon; Suhana Arshad; Ibrahim Abdul Razak

2012-01-01

337

4-Hy-droxy-3-meth-oxy-benzaldehyde 4-ethyl-thio-semicarbazone.  

Science.gov (United States)

In the crystal structure of the title compound, C11H15N3O2S, the C-N-N-C and C-N-C-C torsion angles involving the benzene ring and ethyl group are 11.91?(15) and 99.4?(2)°, respectively. An intra-molecular N-H?N hydrogen bond is observed. In the crystal, mol-ecules are linked via N-H?O and N-H?S hydrogen bonds into a three-dimensional hydrogen bonded network. Finally, the molecules show a herringbone arrangement when viewed along the a axis. PMID:25249915

de Oliveira, Adriano Bof; Beck, Johannes; Daniels, Jörg; Feitosa, Bárbara Regina Santos

2014-08-01

338

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...building operations called tire building machine operators, who use solvents containing...passing the carbon disulfide through 13x molecular sieve). 4.2. Benzene, reagent...ideal gas 25 °C and 760 mm 78.11=molecular weight of benzene 8. Backup...

2010-07-01

339

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

... III. Signs and Symptoms Direct skin contact...the skin. Local effects of benzene vapor...initial stimulatory effect on the central nervous...followed by a period of depression, drowsiness... The detrimental effect on the blood-forming...Early signs and symptoms of benzene...

2010-07-01

340

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Use non-sparking tools to open benzene containers which are...section of charcoal and broken open. The glass wool is removed...Carbon disulfide from a number of sources was analyzed for benzene contamination...liquid chromatograph are: 1. Mobile phase—Methyl...

2010-07-01

 
 
 
 
341

Bio sensing Benzene in the refinery  

International Nuclear Information System (INIS)

A biosensor based on Pseudomonas putida cells was utilized for Benzene analysis in air of an oil refinery. Biosensoristic approach was compared to gaschromatografic essay. We also developed bio sensing Benzene genetically modified Escherichia coli and tested them with refinery samples. Microbial biosensor were useful to determine air pollution.

342

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Container means any barrel, bottle, can, cylinder, drum, reaction vessel, storage tank...Benzine do not contain benzene). 2. Formula: C6 H6 (CAS Registry Number...C and 760 mm 78.11=molecular weight of benzene 8. Backup Data. 8.1...

2010-07-01

343

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...benzene. Chemical Abstracts...vapor control systems for all...monitoring. Engineering and work...containers or process equipment...days of the introduction of benzene...subsequent chemical analysis...monitoring systems, passive...one lot of chemical to another...desorption process,...

2010-07-01

344

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

345

Direct Infrared Absorption Spectroscopy of Benzene Clusters  

Science.gov (United States)

In order to find out the global minimum structure of the benzene dimer we engaged in a series of low (0.5 cm-1) and high (0.015 cm-1) resolution direct absorption infrared measurements of benzene clusters in the 3.3 micron region of the fundamental C-H stretch. The benzene clusters are produced in a continuous supersonic expansion generated by a 24-cm long slit nozzle using helium, argon or neon as carrier gases. Low resolution spectra show a red shift in the CH stretch spectral region which is found to increase with increase in cluster size. When using argon, high resolution spectrum reveals new weak absorption lines between the strongest monomer lines, attributed to the Ar-Benzene complexe. Currently we are involved in recording the high resolution spectrum of the benzene dimer using helium as a carrier gas. R. Georges, A. Bonnamy, M Decroi and J Boissoles, {Molecular Physics 100,1551, (2002)

Chandrasekaran, Vijayanand; Biennier, L.; Georges, R.; Arunan, E.; Reddy, K. P. J.

2009-06-01

346

Treatment of MEK and toluene mixtures in biofilters: effect of operating strategy an performance during transient loading.  

Science.gov (United States)

In recent years, biofiltration has been increasingly applied as an air pollution control technology to minimize or eliminate emissions of volatile organic compounds from industrial sources and environmental remediation activities. Although the ability of this technology to maintain high removal efficiency during relatively steady loading conditions has been well established for many waste streams, relatively little research has focused on development of operating strategies that could improve treatment performance during transient loading conditions typical of industrial operations. In the research described herein, two operating strategies were evaluated over a period of 295 days in biofilters treating a model waste gas stream containing a two-component mixture of methyl ethyl ketone (MEK) and toluene. One biofilter was operated as a sequencing batch biofilter (SBB), and the other was operated as a conventional continuous-flow biofilter (CFB). During "normal" steady loading conditions, the model waste stream contained MEK concentrations ranging from 80 to 89 ppmv and toluene concentrations ranging from 28 to 30 ppmv. Both biofilter operating strategies resulted in stable long-term performance with greater than 99% contaminant removal during these normal loading conditions. On a regular basis, the influent MEK and toluene concentrations were temporarily increased to five times the normal influent concentration for the duration of 1 h to test performance during transient "shock loading" conditions. Biofilter performance during the model shock loading conditions demonstrate that SBB operating strategies can result in superior treatment in two important areas: (1) overall mass of contaminants removed and (2) minimum instantaneous removal efficiency. PMID:15112299

Atoche, Jorge C; Moe, William M

2004-05-20

347

Fluoro norcholesterol analogues. Synthesis of 6 beta-(2'-fluoro) ethyl-19-norcholest-5(10)-en-3 beta-ol  

International Nuclear Information System (INIS)

A synthetic route for labelling 6 beta-(2'-fluoro)ethyl-19-norcholest-5(10)-en-3 beta-ol (VII) with fluorine-18 was developed to evaluate the potential utility of VII as an adrenal imaging agent. 6 beta-p-Toluene-sulphonyloxymethyl-19-norcholest-5(10)-en-3 beta-ol acetate (I) was converted to the 6 beta-(2'-hydroxy)ethyl (VI) in a five-step process. The treatment of VI with N-N-diethyl (2-chloro-1,1,2,-trifluoroethyl)amine in methylene chloride and subsequent hydrolysis with base gave the required VII. Iodination of VI with triphenoxymethylphosphonium iodide followed by alkaline hydrolysis gave the 6 beta-(2'-iodo)ethyl (IX) which, on treatment with silver fluoride in acetonitrile, furnished the 6 beta-(2'-fluoro)ethyl (VII). Excellent conversion of the 6-beta-(2'-p-toluenesulphonyloxy)-ethyl (X) into VII was also achieved by heating with potassium fluoride for 2 hr in diethylene glycol in 76% yield, which is a readily applicable method for labelling with fluorine-18

348

21 CFR 178.3770 - Polyhydric alcohol esters of oxidatively refined (Gersthofen process) montan wax acids.  

Science.gov (United States)

...flask and adjust to volume. Determine the absorbance...the characteristic benzene peaks in the 250 mµ-260...solution to remove benzene by the procedure under...quantitatively, and adjust to volume in isooctane in...using as solvent xylene-ethyl alcohol in...ratio instead of toluene-ethyl alcohol...

2010-04-01

349

AGONISTIC SENSORY EFFECTS OF AIRBORNE CHEMICALS IN MIXTURES: ODOR, NASAL PUNGENCY, AND EYE IRRITATION  

Science.gov (United States)

Threshold responses of odor, nasal pungency (irritation), and eye irritation were measured for single chemicals (1-propanol, 1-hexanol, ethyl acetate, heptyl acetate, 2-pentanone, 2-heptanone, toluene, ethyl benzene, and propyl benzene) and mixtures of them (two three-component m...

350

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

351

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 ...

352

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. M.

1996-01-01

353

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

354

Characterization of ethyl cellulose polymer.  

Science.gov (United States)

Ethyl cellulose (EC) polymer was characterized for its property before considering the interactions with the plasicizer. Ethocel Std.10 FP Premium from Dow chemical company USA was tested for its solubility, morphology and thermal properties. Seven percentage of EC solution in ethanol was found to be the right viscosity used to prepare the film. The EC polymer and EC film without any plasticizers showed almost identical thermal behavior, but in X-ray diffraction showed different arrangements of crystallites and amorphous region. Dynamic mechanical analysis of film showed that without a plasticizer, EC film was not flexible and had very low elongation with high applied force. The aim of the work was to avoid using the commercially available EC dispersions Surelease® and Aquacoat®; both already have additives on it. Instead, Ethocel EC polymer (powder) was characterized in our laboratory in order to find out the properties of polymer before considering the interactions of the polymer with various plasticizers. PMID:21861778

Mahnaj, Tazin; Ahmed, Salah U; Plakogiannis, Fotios M

2013-01-01

355

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

Energy Technology Data Exchange (ETDEWEB)

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 CO{sub 2} is produced as the final product during the reaction process. Highlights: Black-Right-Pointing-Pointer Mg-ferrite/hematite/PANI photocatalysts showed enhanced photocatalytic activity. Black-Right-Pointing-Pointer Ethyl acetate, carboxylic acid and aldehyde were the intermediate products. Black-Right-Pointing-Pointer CO{sub 2} was produced as the final product during the reaction process. Black-Right-Pointing-Pointer 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 CO{sub 2} is determined as the final product during the reaction process.

Shen, Yu [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); School of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028 (China); Zhao, Qidong [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Li, Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia); Yuan, Deling; Hou, Yang [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Liu, Shaomin, E-mail: shaomin.liu@curtin.edu.au [Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia)

2012-11-30

356

Biomarkers of human exposure to benzene  

Energy Technology Data Exchange (ETDEWEB)

Three biomarkers for benzene exposure were developed. The first biomarker, muconic acid in urine, results from the ring opening of a benzene metabolite. A gas chromatography/mass spectroscopy (GC/MS) assay was developed to measure urinary muconic acid, and the analyte in urine samples from workers occupationally exposed to benzene was determined. Workers exposed to benzene concentrations as low as 4.4 ppm over an 8-h day showed higher urinary muconic acid concentrations than did any control individual (p < .005). The second biomarker, S-phenylcysteine (SPC) in hemoglobin (Hb), results from the addition of benzene oxide to a cysteine sulfhydryl group. A GC/MS assay was developed to measure SPC in the blood of F344/N rats and B67C3F mice exposed to benzene by inhalation. The cysteine moiety on rat Hb is at a more accessible site than on Hb of mice or humans, and rats showed considerably higher levels of SPC than did mice. As yet, we have been unable to detect SPC in the globin of humans occupationally exposed to benzene. The third biomarker is SPC in albumin. In humans occupationally exposed to average concentrations of 0, 4.4, 8.4, and 23.1 ppm benzene, 8 h/d, 5 d/wk, SPC increased in the exposed groups linearly, giving a statistically significant slope (p < .001) of 0.044 [+-] 0.008 pmol/mg albumin/ppm. The assay for SPC is arduous and often imprecise; assuming these difficulties can be overcome, muconic acid in urine and SPC in albumin may be useful for accurately determining benzene exposure. 25 refs., 4 figs., 1 tab.

Bechtold, W.E.; Henderson, R.F. (Inhalation Toxicology Research Institute, Albuquerque, NM (United States))

1993-01-01

357

Structure of ionic liquid-benzene mixtures.  

Science.gov (United States)

Neutron diffraction has been used to investigate the structure of liquid mixtures of 1,3-dimethylimidazolium hexafluorophosphate with benzene. Two concentrations of benzene were investigated, namely, 33 mol % and 67 mol %, and show similar structures in each case. The presence of benzene significantly alters the ionic liquid structure, in particular, in the cation-cation interactions, in agreement with the single-crystal structure described recently (Holbrey, J. D.; Reichert, W. M.; Nieuwenhuyzen, M.; Sheppard, O.; Hardacre, C.; Rogers, R. D. Chem. Commun. 2003, 476). In each case, the data was analyzed using an empirical potential structure refinement process. PMID:16851130

Deetlefs, Maggel; Hardacre, Christopher; Nieuwenhuyzen, Mark; Sheppard, Oonagh; Soper, Alan K

2005-02-01

358

46 CFR Table II to Part 150 - Grouping of Cargoes  

Science.gov (United States)

...ethyl ether Vinyl neodecanate Vinyl toluene 14. Acrylates Butyl...phenol Phenol Xylenols 22. Caprolactam Solutions Caprolactam solution 23-29. Unassigned...benzenes Alkyl acrylate-Vinyl pyridine copolymer in...

2010-10-01

359

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-11-15

360

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

 
 
 
 
361

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Oil and gas drilling, production and servicing operations. (vii) Coke oven batteries. (3) The cleaning...encountered are: the primary production and utilization of benzene...Guidelines A minimum battery of tests is to be...

2010-07-01

362

Cyanoborohydride-promoted radical arylation of benzene.  

Science.gov (United States)

Radical biaryl coupling of iodoarenes and benzene can be effectively promoted by tetrabutylammonium cyanoborohydride with air under photoirradiation conditions using a Xe lamp. The utility of this methodology is highlighted by its functional group tolerance and chemoselectivity. PMID:24697750

Kawamoto, Takuji; Sato, Aoi; Ryu, Ilhyong

2014-04-18

363

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...measurements are taken in a random manner over the 8-hour work shift. Random sampling means that any portion...arithmetic average of all such random samples taken on one work...Samples Analyte: Benzene Matrix: Air Procedure:...

2010-07-01

364

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...section applies to all occupational exposures to benzene. Chemical Abstracts Service Registry No. 71-43-2, except as provided in...Sampling and analysis must be performed with procedures meeting the requirements of the standard. There are a...

2010-07-01

365

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...for earnings lost during the period of removal either from a publicly or employer-funded...possible by virtue of the employee's removal. (j) Communication of benzene hazards...characterized by exhilaration, nervous excitation, and/or giddiness, followed...

2010-07-01

366

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...The carbon disulfide layer is removed, dried with anhydrous sodium sulfate, and distilled. The recovered carbon disulfide...4. Desorption data. Samples were prepared by injecting liquid benzene onto the A section of charcoal...

2010-07-01

367

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Guidelines, Benzene I. Physical and Chemical Data A. Substance identification. 1. Synonyms: Benzol, benzole, coal naphtha, cyclohexatriene, phene, phenyl hydride, pyrobenzol. (Benzin, petroleum benzin and Benzine do not contain...

2010-07-01

368

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...a number of methods available for monitoring...standard solutions. 4. Reagents. 4.1. Chromatographic...disulfide (CS2 ). Most commercially available carbon disulfide contains... 4.2. Benzene, reagent grade. 4.3....

2010-07-01

369

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the appearance of red cells. c. Description...smear for immature white cells such as band forms...myeloblasts. Any nucleate or multinucleated red blood cells should be reported. Large...indication of benzene-induced toxicity. An...

2010-07-01

370

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...pattern is more likely to be associated with benzene toxicity and merits thorough investigation. Anemia, leukopenia, macrocytosis or an abnormal differential white blood cell count should alert the physician to further investigate and/or refer...

2010-07-01

371

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...gloves, sleeves, aprons, etc.) over any parts of your body that could be exposed to liquid benzene. C. Eye and...cell and white cell counts are influenced by altitude, race, and sex, and therefore should be determined by the...

2010-07-01

372

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...pulmonary tissue. There is some absorption through the skin. Absorption may be more rapid in the...addition, there is benzene absorption through the skin. Local...that place the employee at increased risk. To assist the...

2010-07-01

373

Environmental effect of rapeseed oil ethyl ester  

International Nuclear Information System (INIS)

Exhaust emission tests were conducted on rapeseed oil methyl ester (RME), rapeseed oil ethyl ester (REE) and fossil diesel fuel as well as on their mixtures. Results showed that when considering emissions of nitrogen oxides (NOx), carbon monoxide (CO) and smoke density, rapeseed oil ethyl ester had less negative effect on the environment in comparison with that of rapeseed oil methyl ester. When fuelled with rapeseed oil ethyl ester, the emissions of NOx showed an increase of 8.3% over those of fossil diesel fuel. When operated on 25-50% bio-ester mixed with fossil diesel fuel, NOx emissions marginally decreased. When fuelled with pure rapeseed oil ethyl ester, HC emissions decreased by 53%, CO emissions by 7.2% and smoke density 72.6% when compared with emissions when fossil diesel fuel was used. Carbon dioxide (CO2) emissions, which cause greenhouse effect, decreased by 782.87 g/kWh when rapeseed oil ethyl ester was used and by 782.26 g/kWh when rapeseed oil methyl ester was used instead of fossil diesel fuel. Rapeseed oil ethyl ester was more rapidly biodegradable in aqua environment when compared with rapeseed oil methyl ester and especially with fossil diesel fuel. During a standard 21 day period, 97.7% of rapeseed oil methyl ester, 98% of rapeseed oil ethyl ester and only 61.3% of fossil diesel fuel were biologically decomposed. (author)

374

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

375

Toluene removal from air by Dieffenbachia in a closed environment  

Science.gov (United States)

Higher plants are likely to play a major role in bioregeneration systems for food, air and water supplies. Plants may also contribute by the removal of toxic organic substances from the air of a closed environment. Dieffenbachia amoena plants were exposed to 0 to 1.2 × 106 ?g toluene.m-3 at light intensities of 35 and 90 ?mol.m-2.s-1 in sealed chambers. Toluene removal, photosynthesis and respiration were measured. An increased light inten-sity increased the rate of toluene removal five-fold over the rate at the lower intensity; the kinetics suggest active regulation by the plant. The removal rate saturated at 2700 ?g toluene.h-1 at the lower intensity and failed to saturate at the higher intensity. Toluene exposure inhibited photosynthesis and respiration only transiently and without correlation to toluene concentration. These plants can act as efficient scavengers of toluene in a contaminated environment. 1990 and 1991 NASA/ASEE Summer Faculty Research Fellow, National Science and Technology Laboratory, John C. Stennis Space Center, Stennis Space Center, MS 39529

Porter, J. R.

1994-11-01

376

Acute cardiotoxic effects of high dose toluene: an experimental study  

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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

377

Linking Toluene Degradation with Specific Microbial Populations in Soil  

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Phospholipid fatty acid (PLFA) analysis of a soil microbial community was coupled with 13C isotope tracer analysis to measure the community’s response to addition of 35 ?g of [13C]toluene ml of soil solution?1. After 119 h of incubation with toluene, 96% of the incorporated 13C was detected in only 16 of the total 59 PLFAs (27%) extracted from the soil. Of the total 13C-enriched PLFAs, 85% were identical to the PLFAs contained in a toluene-metabolizing bacterium isolated from the same so...

Hanson, Jessica R.; Macalady, Jennifer L.; Harris, David; Scow, Kate M.

1999-01-01

378

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 mechan

379

Crystal structure of ethyl 2-(diethoxyphosphoryl-2-(2,3,4-trimethoxyphenylacetate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, C17H27O8P, was prepared by Michaelis–Arbuzov reaction of ethyl 2-bromo-2-(2,3,4-trimethoxyphenylacetate and triethyl phosphite. Such compounds rarely crystallize, but single crystals were recovered after the initial oil was left for approximately 10 years. The bond angle of the sp3-hybridized C atom connecting the benzene derivative with the phospho unit is widened marginally [112.5?(2°]. The terminal P—O bond length of 1.464?(2 ? clearly indicates a double bond, whereas the two O atoms of the ethoxy groups connected to the phosphorous atom have bond lengths of 1.580?(2?Å and 1.581?(3?Å. The three methoxy groups emerge out of the benzene-ring plane due to steric hindrance [C—C—O—C torsion angles = ?179.9?(3°, ?52.9?(4° and 115.3?(4°]. In the crystal, inversion dimers linked by pairs of C—H...O=P hydrogen bonds generate R22(14 loops. The chosen crystal was modelled as a non-merohedral twin.

Moritz Schubert

2014-09-01

380

21 CFR 184.1293 - Ethyl alcohol.  

Science.gov (United States)

...CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY...Ethyl alcohol (ethanol) is the chemical C2 H5 OH. (b) The ingredient...meets the specifications of the “Food Chemicals Codex,” 4th ed....

2010-04-01

 
 
 
 
381

The cyanogen-ethyl ethers of glycerin  

International Nuclear Information System (INIS)

The cyanogen-ethylation is one of the characteristic reaction of hydroxyl comprising compounds and run with addition them to acryl nitride. The catalysis of process are substances, which have basic character

382

Selective dimerization of 1,6-diynes catalyzed by ionic liquid-supported nickel complexes in an ionic liquid/toluene biphasic system.  

Science.gov (United States)

A NiCl(2)-6H(2)O/Zn reagent with a 2-aryliminomethylpyridine ligand catalyzed cyclization/polymerization of 1,6-diynes to yield mainly the corresponding poly(1,3-butadienylene) compounds, whereas NiBr(2)-3H(2)O/Zn with the use of 3-(2-(2-methoxyethoxy)-ethyl)-1-methyl-1H-imidazol-3-ium bromide as a ligand converted 1,6-diynes to the corresponding annulated 1,3,5,7-cyclooctatetraenes in a biphasic solvent system consisting of toluene and an ionic liquid. PMID:19137178

Goswami, Avijit; Ito, Taichi; Saino, Naoko; Kase, Kouki; Matsuno, Chikashi; Okamoto, Sentaro

2009-01-28

383

Catalytic oxidation of dichloromethane and toluene over platinum alumite catalyst.  

Science.gov (United States)

Catalytic oxidation technology is one of the most promising technologies for the reduction of volatile organic compound (VOC) emissions. It is very necessary to study the catalytic oxidation of mixture of VOCs and volatile organic compounds (CVOCs), because VOCs are always emitted accompanying with CVOCs. Hence, the catalytic oxidation reaction of toluene and CH2Cl2 is explored on a platinum alumite catalyst in this work. The results show that the addition of toluene has no effect on the decomposition of CH2Cl2, although it can suppress CH3Cl formation because the steam generated from the catalytic combustion of toluene suppresses the formation of CH3Cl from CH2Cl2. High concentrations of CH2Cl2 have a negative effect on the catalytic combustion of toluene. PMID:18054162

Wang, Lifeng; Sakurai, Makoto; Kameyama, Hideo

2008-06-15

384

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

385

Solubility data for toluene in various aqueous alkanolamine solutions  

International Nuclear Information System (INIS)

This paper is the second part concerning the study of the solubility of aromatics in aqueous alkanolamine solutions. Vapor pressures over (liquid + liquid) mixtures and toluene solubility data are reported herein for toluene with pure water and aqueous alkanolamine solutions: monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and diglycolamine[reg] (DGA). Modelling of solubility data are achieved using a simple model based on activity coefficients

386

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

1993-01-01

387

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

388

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

389

Excess parameter studies on the binary mixtures of toluene with ketones at different temperatures  

Energy Technology Data Exchange (ETDEWEB)

Density, rho, ultrasonic speed, u, and viscosity, eta of binary mixtures of toluene with acetone (AC), ethyl methyl ketone (EMK), and acetophenone (AP), including those of pure liquids are measured over the entire composition range at temperatures (298.15, 303.15, and 308.15) K respectively. From these experimental results, deviations in isentropic compressibility, DELTAk{sub s} and ultrasonic speed, DELTAu, excess intermolecular free length, L{sub f}{sup E}, excess Gibbs free energy of activation, DELTAG*{sup E}, partial molar volumes (V-bar{sub m,1}{sup 0},V-bar{sub m,2}{sup 0},V-bar{sub p}hi{sub ,1}{sup 0},V-bar{sub p}hi{sub ,2}{sup 0}) partial molar compressibilities (K-bar{sub m,1}{sup 0},K-bar{sub m,2}{sup 0},K-bar{sub p}hi{sub ,1}{sup 0}, and K-bar{sub p}hi{sub ,2}{sup 0}) and their excess values (V-bar{sub m,1}{sup 0E},V-bar{sub m,2}{sup 0E},V-bar{sub p}hi{sub ,1}{sup 0E},V-bar{sub p}hi{sub ,2}{sup 0E},K-bar{sub m,1}{sup 0E},K-bar{sub m,2}{sup 0E}, K-bar{sub p}hi{sub ,1}{sup 0E}, and K-bar{sub p}hi{sub ,2}{sup 0E}) of the components at infinite dilution are calculated. The values of DELTAk{sub s} and L{sub f}{sup E} are found to be negative, and those of DELTAu and DELTAG*{sup E} are found to be positive, indicating the presence of specific interactions between toluene and ketone molecules and the interactions follow the order: AC > EMK > AP.

Rajagopal, K. [Department of Physics, Government College of Engineering, Tirunelveli 627 007, Tamilnadu (India); Chenthilnath, S., E-mail: chenthilnaths@rediffmail.co [Department of Physics, Satyam College of Engineering and Technology, Satyam Nagar, Aralvaimozhy, Nagercoil 629 301, Tamilnadu (India)

2010-05-15

390

Kinetics of proton transfer between ortho substituted benzoic acids and the carbinol base of crystal violet in toluene. Ortho effect on the reactivity of benzoic acids in apolar aprotic solvents.  

Science.gov (United States)

Apolar aprotic solvents are particularly advantageous for investigating the intrinsic ortho effect free from complications of specific solvent effects. A kinetic study for toluene-phase proton transfers between ortho F, Cl, Br, I, OMe, OEt, OPh, OAc, Me, NO(2), COMe, COPh, OH, NH(2), and H benzoic acids and crystal violet carbinol base has shown the forward rate constant (log k(+1)) is the most appropriate reactivity parameter in toluene. log k(+1) (toluene) as compared to other reported reactivity parameters in benzene, toluene, or chlorobenzene has been found more sensitive to the ortho substituent effect. The regression results of the correlation of log k(+1) (toluene) of the acids (except OH and NH(2) substituted ones) according to seven ortho effect models are all very significant, and the best result is given by Fujita-Nishioka's model. The overall analysis reveals that a substituent's ortho effect pattern is a 58:24:18 ratio of its ordinary electrical, proximity electrical, and steric effects and that the proximity electrical effect is the major component to account for the peculiarity of the substituent's ortho effect. The results further favor the transmission of this effect mainly through the molecular cavity. The effect may, however, be outweighed by the steric component for bulky enough substituents, e.g., Me. The enhanced strength exhibited by salicylic acid in toluene has been quantitatively described using Pytela-Lis?ka's ?(HB)(i) parameter. The abnormally high log k(+1) observed for anthranilic acid in toluene has been ascribed to a very extensive homoconjugation in its acid-acid anion complex induced by the acid's three hydrogen bond donors. PMID:21504215

Sen Gupta, Susanta K; Mishra, Sangeeta

2011-05-12

391

Benzylsuccinate Formation as a Means of Anaerobic Toluene Activation by Sulfate-Reducing Strain PRTOL1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Permeabilized cells of toluene-mineralizing, sulfate-reducing strain PRTOL1 catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. Recent in vitro studies with two toluene-mineralizing, denitrifying bacteria demonstrated the same fumarate addition reaction and indicated that it may be the first step of anaerobic toluene degradation. This study with strain PRTOL1 shows that anaerobic toluene activation by fumarate addition occurs in bacteria as dispar...

Beller, H. R.; Spormann, A. M.

1997-01-01

392

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...

Wang, R. S.; Nakajima, T.

1992-01-01

393

Metabolic by-products of anaerobic toluene degradation by sulfate-reducing enrichment cultures.  

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Two dead-end metabolites of anaerobic toluene transformation, benzylsuccinic acid and benzylfumaric acid, accumulated in sulfate-reducing enrichment cultures that were fed toluene as the sole carbon source. Stable isotope-labeled toluene and gas chromatography-mass spectrometry were used to confirm that the compounds resulted from toluene metabolism. The two metabolites constituted less than 10% of the toluene carbon (over 80% was mineralized to carbon dioxide, according to a previous study)....

Beller, H. R.; Reinhard, M.; Grbic?-galic?, D.

1992-01-01

394

Genetic effects of thinner, benzene and toluene in Drosophila melanogaster. 1. Sex Chromosome loss and non-disjunction  

Directory of Open Access Journals (Sweden)

Full Text Available Se estudiaron algunos efectos genéticos de tiner, benceno y tolueno en Drosophila melanogaster, tales como la pérdida de los cromosomas sexuales y la no disyunción de los mismos en machos y en hembras. El orden de toxicidad fue benceno > tolueno > tiner. La viabilidad se redujo con el benceno y el tolueno pero no con el tíner. Solamente las concentraciones más altas de benceno y tolueno indujeron la pérdida de los cromosomas sexuales y la no disyunción en los machos. El tiner no produjo dichos efectos genéticos.

Rosario Rodr\\u00EDguez Arnaiz

1985-01-01