Sample records for benzene

  1. Biochemical toxicity of benzene. (United States)

    Rana, S V S; Verma, Yeshvandra


    Human exposure to benzene in work environment is a global occupational health problem. After inhalation or absorption, benzene targets organs viz. liver, kidney, lung, heart and brain etc. It is metabolized mainly in the liver by cytochrome P450 multifunctional oxygenase system. Benzene causes haematotoxicity through its phenolic metabolites that act in concert to produce DNA strand breaks, chromosomal damage, sister chromatid exchange, inhibition of topoisomerase II and damage to mitotic spindle. The carcinogenic and myelotoxic effects of benzene are associated with free radical formation either as benzene metabolites or lipid peroxidation products. Benzene oxide and phenol have been considered as proheptons. Liver microsomes play an important role in biotransformation of benzene whereas in kidney, it produces degenerative intracellular changes. Cohort studies made in different countries suggest that benzene induces multiple myeloma in petrochemical workers. Though extensive studies have been performed on its toxicity, endocrinal disruption caused by benzene remains poorly known. Transgenic cytochrome P450 IIE1 mice may help in understanding further toxic manifestations of benzene.

  2. Benzene from Traffic

    DEFF Research Database (Denmark)

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

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

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

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter


    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated usi...

  4. Risk factor benzene

    Energy Technology Data Exchange (ETDEWEB)

    Stobbe, H.


    Nearly one hundred years ago clinical and epidemiological studies have already assigned benzene as a markedly haematotoxic substance. Nowadays benzene is known as an important professional noxa, which is straight off directed against the haematopoietic system, essentially to a dose-time-effect. By this it can be taken as a model also for other noxious substances. Similar solvents often contain so-called 'hidden benzene', that means not declared benzene, so that the consumer doesn't know what dangerous substance are available for his personal use. Impairments caused by benzene mostly are manifested earliest after months, years or for tens of years, and the point is, that these haematopoietic disorders are irreversible disturbances of the haematopoietic stem cell compartment. The consequence of this fact is a deep involvement of the proliferation of the erythro-, mono-, granulo- and thrombopoietic cell lines, mostly with predominance of one of these myeloproliferative cell systems. In the further progression of the impairments due to benzene three different clinical pictures can be observed: the aplastic bone marrow syndrome (i.e. aplastic anemia), the haematopoietic dysplasia (i.e. preleukemia) and the acute leukemias (with the subtypes erythroleukosis, myeloblastic-promyelocytic or myelomonocytic from respectively). Also the transition from one clinical picture to another is possible.

  5. Fuel Dependence of Benzene Pathways

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  6. Biomarkers of environmental benzene exposure

    Energy Technology Data Exchange (ETDEWEB)

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


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

  7. Double photoionization of halogenated benzene

    Energy Technology Data Exchange (ETDEWEB)

    AlKhaldi, Mashaal Q. [Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Wehlitz, Ralf, E-mail: [Synchrotron Radiation Center, University of Wisconsin–Madison, Stoughton, Wisconsin 53589 (United States)


    We have experimentally investigated the double-photoionization process in C{sub 6}BrF{sub 5} using monochromatized synchrotron radiation. We compare our results with previously published data for partially deuterated benzene (C{sub 6}H{sub 3}D{sub 3}) over a wide range of photon energies from threshold to 270 eV. A broad resonance in the ratio of doubly to singly charged parent ions at about 65 eV appears shifted in energy compared to benzene data. This shift is due to the difference in the bond lengths in two molecules. A simple model can explain the shape of this resonance. At higher photon energies, we observe another broad resonance that can be explained as a second harmonic of the first resonance.

  8. Functionalization of benzene by superhalogens (United States)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj


    We perform ab initio MP2/6-311++G(d,p) calculations to analyze the molecular properties and aromaticity of NO3, BO2 as well as BF4 superhalogen substituted benzene and compare them with well known electron withdrawing group substituted benzene such as C6H5F and C6H5CN in neutral and ionic forms. It has been noticed that the properties (including aromaticity) of C6H5BO2 closely resemble those of C6H5F and C6H5CN. On the contrary, C6H5NO3 possesses some quite different properties such as high electron affinity, small frontier orbital energy gap and enhanced aromaticity. It is also revealed that C6H5BF4 exists only in the form of C6H5F⋯BF3 complex.

  9. Natural Biological Attenuation of Benzene in Groundwater

    Institute of Scientific and Technical Information of China (English)


    Benzene has been found in subsurface unsaturated soil and groundwater beneath a petro-chemical plant. Although the groundwater contained several mg/L of benzene in the area immediately beneath the source, benzene was not detected in monitoring wells approximately 800m down stream. All kinds of physical processes such as adsorption and advection/dispersion are considered to account for the observed attenuation. The results indicated that the attenuation was primarily due to natural biological processes occurring within the aquifer. The evidence for the natural bioremediation of benzene from the groundwater included: (1) analysis of groundwater chemistry, (2) laboratory studies demonstrating benzene biodegradation in aquifer samples, and (3) computer simulations examining benzene transport. Laboratory experiments indicated that for conditions similar to those in the plume, the aerobic degradation of benzene by the naturally occurring microorganisms in the polluted groundwater samples was quite rapid with a half-life time of from 5 to 15 days. In situ analyses indicated the level of dissolved oxygen in the groundwater was over 2mg/L. Thus, oxygen should not limit the biodegradation. In fact, the benzene was also shown to degrade under anaerobic conditions. The results from the modeling simulations indicate that biodegradation is the dominant process influencing attenuation of the benzene.

  10. Carcinogenic effects of benzene: Cesare Maltoni's contributions. (United States)

    Mehlman, Myron A


    Cesare Maltoni's contributions to understanding, identifying, and characterizing widely used commercial chemicals in experimental animals are among the most important methods developed in the history of toxicology and serve to protect working men and women, the general population, and our environment from hazardous substances. Maltoni developed experimental methods that have reached the "platinum standard" for protection of public health. Benzene was among the 400 or more chemicals that Maltoni and his associates tested for carcinogenicity. In 1976, Maltoni reported that benzene is a potent experimental carcinogen. Maltoni's experiments clearly demonstrated that benzene is carcinogenic in Sprague-Dawley rats, Wistar rats, Swiss mice, and RF/J mice when administered by inhalation or ingestion. Benzene caused carcinomas of the Zymbal gland, oral cavity, nasal cavities; cancers of the skin, forestomach, mammary glands, and lungs; angiosarcomas and hepatomas of the liver; and hemolymphoreticular cancers. Thus, benzene was shown to be a multipotential carcinogen that produced cancers in several species of animals by various routes of administration. On November 2, 1977, Chemical Week reported that Maltoni provided a "bombshell" when he demonstrated the "first direct link" between benzene and cancer. In this paper, I shall summarize early experiments and human studies and reports; Maltoni's experimental contribution to understanding the carcinogenicity of benzene in humans and animals; earlier knowledge concerning benzene toxicity; and benzene standards and permissible exposure levels.

  11. Production of Phenol from Benzene via Cumene (United States)

    Daniels, D. J.; And Others


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

  12. Chemical of current interest--benzene. (United States)

    Marcus, W L


    Benzene is one of the world's major commodity chemicals. It is derived from petroleum and coal and is used both as a solvent and as a starting material in chemical syntheses. The numerous industrial uses of benzene over the last century need not be recounted here, but the most recent addition to the list of uses of benzene is as a component in a mixture of aromatic compounds added to gasoline for the purpose of replacing lead compounds as anti-knock ingredients. The best known and longest recognized toxic effect of benzene is the depression of bone marrow function seen in occupationally exposed individuals. These people have been found to display anemia, leucopenia, and/or thrombocytopenia. When pancytopenia, i.e., the simultaneous depression of all three cell types, occurs and is accompanied by bone marrow necrosis, the syndrome is called aplastic anemia. In addition to observing this decrease in humans and relating it to benzene exposure, it has been possible to establish animal models which mimic the human disease. The result has been considerable scientific investigation into the mechanism of benzene toxicity. Although the association between benzene exposure and aplastic anemia has been recognized and accepted throughout most of this century, it is only recently that leukemia, particularly of the acute myelogenous type, has been related to benzene. The acceptance of benzene as an etiological agent in aplastic anemia in large measure derives from our ability to reproduce the disease in most animals treated with sufficiently high doses of benzene over the necessary time period. Unfortunately, despite extensive efforts in several laboratories, it has not been possible to establish a reproducible, reliable model for the study of benzene-induced leukemia. The recent demonstration that several animals exposed to benzene either by inhalation or in the drinking water during studies by Drs. B. Goldstein and C. Maltoni suggests that such a model may be forthcoming

  13. Anaerobic benzene oxidation by Geobacter species. (United States)

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


    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.

  14. Mechanistic considerations in benzene physiological model development

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  15. Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei. (United States)

    Sabourin, P J; Sun, J D; MacGregor, J T; Wehr, C M; Birnbaum, L S; Lucier, G; Henderson, R F


    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. Exposure to the same level of benzene for an additional 2 weeks did not further increase the frequency of micronuclei in PCEs. These results indicate

  16. Interphase cytogenetics of workers exposed to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.; Wang, Yunxia; Venkatesh, P. [Univ. of California, Berkeley, CA (United States)] [and others


    Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median=31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (>31 ppm, n=22) increased the hyperdiploid frequency of chromosome 9 (p<0.01), but lower exposure (<31 ppm, n=21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperdiploidy in exposed workers correlated with their urinary phenol level (r= 0.58, p < 0.0001), a measure of internal benzene close. A significant correlation was also found between hyperdiploicly and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r=-0.44, p=0.003) but not in controls (r=-0.09, P=0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations. 35 refs., 3 figs., 2 tabs.

  17. Benzene metabolites induce apoptosis in lymphocytes. (United States)

    Martínez-Velázquez, M; Maldonado, V; Ortega, A; Meléndez-Zajgla, J; Albores, A


    Benzene is an important environmental pollutant with important health implications. Exposure to this aromatic hydrocarbon is associated with hematotoxicity, and bone marrow carcinogenic effects. It has been shown that benzene induces oxidative stress, cell cycle alterations, and programmed cell death in cultured cells. Hepatic metabolism of benzene is thought to be a prerequisite for its bone marrow toxicity. Nevertheless, there are no reports on the cellular effects of reactive intermediates derived from hepatic metabolism of benzene. Thus, the goal of this project was to determine the cellular alterations of benzene metabolites produced by the cultured hepatic cell line HepG2. Supernatants collected from these cells were applied to a culture of freshly isolated lymphocytes. A higher decrease in cell viability was found in cells exposed to these supernatants than to unmetabolized benzene. This viability decrease was due to apoptosis, as determined by Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) assay and internucleosomal fragmentation of DNA. When supernatants were analyzed by HPLC, we found that not all the hydrocarbon was biotransformed, since a 28 microM concentration (37%) remained. The only metabolite found in the culture medium was muconic acid. The present results show that muconic acid derived from benzene metabolism is able to cooperate with the pollutant for the induction of apoptosis in rat lymphocytes.

  18. Reduction of benzene toxicity by toluene. (United States)

    Plappert, U; Barthel, E; Seidel, H J


    BDF1 mice were exposed in inhalation chambers to benzene (900 ppm, 300 ppm) and/or toluene (500 ppm, 250 ppm) 6 hr per day, 5 days per week, for up to 8 weeks. Benzene alone induced a slight anemia after 4 and 8 weeks and a reduction of BFU-E and CFU-E numbers in the marrow. The coexposure to toluene reduced the degree of anemia. These results confirm previous studies where toluene was found to reduce benzene toxicity. This protective effect was most pronounced when DNA damage was studied in peripheral blood cells, bone marrow, and liver using the single cell gel (SCG) assay. With benzene alone, either with 300 or 900 ppm, a significant increase in DNA damage was detected in cells sampled from all three organs. Toluene alone did not induce a significant increase in DNA damage. The coexposure of benzene and toluene reduced the extent of DNA damage to about 50% of benzene alone. This result is considered a clear indication for a protective effect of toluene on the genetic toxicity of benzene.

  19. Excited state of protonated benzene and toluene

    Energy Technology Data Exchange (ETDEWEB)

    Esteves-López, Natalia; Dedonder-Lardeux, Claude; Jouvet, Christophe, E-mail: [Aix-Marseille Université, CNRS, UMR-7345, Physique des Interactions Ioniques et Moléculaires (PIIM), Marseille (France)


    We present photo-fragmentation electronic spectra of the simplest protonated aromatic molecules, protonated benzene and toluene, recorded under medium resolution conditions and compared with the photo-fragmentation spectrum of protonated pyridine. Despite the resolution and cold temperature achieved in the experiment, the electronic spectra of protonated benzene and toluene are structure-less, thus intrinsically broadened. This is in agreement with the large geometrical changes and the fast dynamic toward internal conversion predicted by ab initio calculations for protonated benzene [Rode et al., J. Phys. Chem. A 113, 5865–5873 (2009)].

  20. [Epigenic modifications associated with low benzene exposure]. (United States)

    Fustinoni, Silvia; Bollati, Valentina; Bertazzi, Pier Alberto


    DNA methylation, mitochondrial DNA copy number and telomeres shortening are cellular modifications associated with an increasing number of tumors, cardiovascular and aging diseases. In our studies these modifications were evaluated in subjects occupationally exposed to low levels of benzene and in the general population. In peripheral blood lymphocytes a decrease of DNA methylation with the increase of personal benzene exposure was found, both in Alu and LINE-1 repetitive elements, and in the global DNA. Telomere length shortening in subjects exposed to traffic exhausts and an increase in mitochondrial DNA copy number correlated to benzene exposure was also found. DNA methylation measured in specimen repeats collected at intervals of 8 years decreased more markedly in exposed subjects than in controls. Our studies highlighted the association of epigenetic modifications of DNA with low benzene exposure.

  1. Anaerobic benzene oxidation via phenol in Geobacter metallireducens. (United States)

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


    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.

  2. Benzene toxicity of the occurrence of benzene in the ambient air of the Houston area

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.C.


    This study was conducted by either literature review or actual field survey. Results are summarized as follows: (1) long-term occupational exposure of workers to benzene vapor at levels of 3 to 7 ppM, 2 to 3 ppM and 1.6 ppM may result in a decreased level of leucocyte alkaline phosphates, an increased incidence of chromosome aberrations and an increased level of ALA in erythrocytes, respectively; (2) benzene is capable of causing fetotoxic effects in animals at levels as low as 10 ppM by volume; (3) exposure of animals to or less than 1 ppM benzene vapor may result in leucopenia, an inverse ratio of muscle antagonist chronaxy and a decreased level of ascorbic acid in fetus's and mother's liver as well as whole embryo; (4) benzene is causally associated with the increased incidence of pancytopenia, including unicytopenia, bicytopenia and aplastic anemia, and chromosome aberrations in occupational exposure population, and at best benzene must also be considered as a leukemogen; (5) since it can be emitted into the atmosphere from both man-made and natural sources, benzene in some concentrations is presented everywhere in the various compartments of the environment; (6) the findings of the emission of benzene from certain natural sources indicate that reducing benzene to a zero-level of exposure is theoretically impossible; (7) the annual average of benzene concentration detected in the Houston ambient air is 2.50 ppB, which is about 2.4 times higher than the nation-wide annual average exposure level and may have some health implications to the general public; and (8) in the Houston area, stationary sources are more important than mobile sources in contributing to benzene in the ambient air.

  3. Ionic Liquid Catalyst Used in Deep Desulfuration of the Coking Benzene for Producing Sulfurless Benzene

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xia-Ping; WANG Yan-Liang; MENG Fan-Wei; FAN Xing-Ming; QIN Song-Bo


    For the widening need of benzene used in organic synthesis, ionic liquid catalyst was prepared to study the process of deep desulfuration in the coking benzene. The result shows that the effect of de-thiophene by the ionic liquid catalyst (N-methyl imidazolium hydrogen sulfate [Hmim][HSO4]) is related to its acid function value.Hammett indicator was used to determine the acid function value H0 of the ionic liquid. It can be concluded that while the acid function value is in the range from -4 to -12, the ionic liquid catalyst can make the concentration certain acid quantity and strength, the ionic liquid catalyst helps to form alkyl thiophene through Friedel-Crafts reaction, which differs from the character of benzene and it is absolutely necessary for the separation and refinement of benzene. But overabundant quantity and higher acid value of [Hmim][HSO4] are more suitable for the side copolymerization of benzene, thiophene and alkene, thereby affecting repeated use of the ionic liquid catalyst([Hmim][HSO4]). In our research, thiophene derivant produced by desulfurization in the coking benzene was used as the polymer to provide the passing channel of the charges. The ionic liquid composition in poor performance after repeated use was made to prepare conductive material (resisting to static electricity) as an "electron-receiving" and "electron-giving" doping agent. The result shows that thiophene derivant after desulfuration in the coking benzene can be used to prepare doping conductive materials.

  4. Behavioral changes in mice following benzene inhalation. (United States)

    Evans, H L; Dempster, A M; Snyder, C A


    Although benzene is an important occupational health hazard and a carcinogen, the possibility that behavioral changes may forewarn of the later-occurring hematological changes has not been investigated. A time-sampling protocol was used to quantify the occurrence of 7 categories of behavior in the homecage following daily 6-hr exposures to two strains of adult mice (CD1 and C57BL/6J). The behavioral categories were stereotypic behavior, sleeping, resting, eating, grooming, locomotion, and fighting. The inhalation exposures were designed to reflect occupational exposure. Dynamic vapor exposure techniques in standard inhalation chambers were employed. Exposure to 300 or 900 ppm benzene increased the occurrence of eating and grooming and reduced the number of mice that were sleeping or resting. The responses to benzene of both the CD1 and the C57 strains were similar. The positive findings with benzene inhalation indicate the utility of behavioral investigations into the toxicology of inhaled organic solvents. The methods described herein illustrate an objective observation of animal behavior that is capable of documenting toxicity and of guiding detailed follow-up studies aimed at mechanism of action.

  5. Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

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    Zhengjun Zhang


    Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

  6. Recent advances in the metabolism and toxicity of benzene. (United States)

    Kalf, G F


    Benzene is a heavily used industrial chemical, a petroleum byproduct, an additive in unleaded gas, and a ubiquitous environmental pollutant. Benzene is also a genotoxin, hematotoxin, and carcinogen. Chronic exposure causes aplastic anemia in humans and animals and is associated with increased incidence of leukemia in humans and lymphomas and certain solid tumors in rodents. Bioactivation of benzene is required for toxicity. In the liver, the major site of benzene metabolism, benzene is converted by a cytochrome P-450-mediated pathway to phenol, the major metabolite, and the secondary metabolites, hydroquinone and catechol. The target organ of benzene toxicity, the hematopoietically active bone marrow, metabolizes benzene to a very limited extent. Phenol is metabolized in the marrow cells by a peroxidase-mediated pathway to hydroquinone and catechol, and ultimately to quinones, the putative toxic metabolites. Benzene and its metabolites appear to be nonmutagenic, but they cause myeloclastogenic effects such as micronuclei, chromosome aberrations, and sister chromatid exchange. It is unknown whether these genomic changes, or the ability of the quinone metabolites to form adducts with DNA, are involved in benzene carcinogenicity. Benzene, through its active metabolites, appears to exert its hematological effects on the bone marrow stromal microenvironment by preventing stromal cells from supporting hemopoiesis of the various progenitor cells. Recent advances in our understanding of the mechanisms by which benzene exerts its genotoxic, hematotoxic, and carcinogenic effects are detailed in this review.

  7. Structural basis of enzymatic benzene ring reduction. (United States)

    Weinert, Tobias; Huwiler, Simona G; Kung, Johannes W; Weidenweber, Sina; Hellwig, Petra; Stärk, Hans-Joachim; Biskup, Till; Weber, Stefan; Cotelesage, Julien J H; George, Graham N; Ermler, Ulrich; Boll, Matthias


    In chemical synthesis, the widely used Birch reduction of aromatic compounds to cyclic dienes requires alkali metals in ammonia as extremely low-potential electron donors. An analogous reaction is catalyzed by benzoyl-coenzyme A reductases (BCRs) that have a key role in the globally important bacterial degradation of aromatic compounds at anoxic sites. Because of the lack of structural information, the catalytic mechanism of enzymatic benzene ring reduction remained obscure. Here, we present the structural characterization of a dearomatizing BCR containing an unprecedented tungsten cofactor that transfers electrons to the benzene ring in an aprotic cavity. Substrate binding induces proton transfer from the bulk solvent to the active site by expelling a Zn(2+) that is crucial for active site encapsulation. Our results shed light on the structural basis of an electron transfer process at the negative redox potential limit in biology. They open the door for biological or biomimetic alternatives to a basic chemical synthetic tool.

  8. [Materials for the substantiation of the biological MAC of benzene]. (United States)

    Ulanova, I P; Avilova, G G; Karpukhina, E A; Karimova, L K; Boĭko, V I; Makar'eva, L M


    Relatively great amount of benzene-originated phenol, the presence of a definite relationship between phenol amount in the urine and benzene content in the air indicate that it is reasonable to use a phenol sample as an exposure test. To determine the intensity of benzene exposure, data on phenol content in the urine of people working at some big-tonnage enterprises has been analyzed. On the basis of the national and foreign literature data on the correlation between the phenol urine concentration and the level of benzene exposure a regression equation was deduced, which has made it possible to calculate phenol content in the urine on the level of average working day benzene concentration adopted in the USSR. This value equals 15 mg/l, which was proposed as a biological benzene MAC.

  9. Physiological and phylogenetic characterization of a stable chlorate-reducing benzene-degrading microbial community

    NARCIS (Netherlands)

    Weelink, S.A.B.; Tan, N.C.G.; Broeke, ten H.; Doesburg, van W.C.J.; Langenhoff, A.A.M.; Gerritse, J.; Stams, A.J.M.


    stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20¿1650 times higher than reported for anaerobic benzene degradation

  10. An efficient synthesis of substituted benzene-1,2-dicarboxaldehydes

    Institute of Scientific and Technical Information of China (English)

    ZHU Peter C; WANG Dei-Haw; LU Kaitao; MANI Neelakandha


    Substituted-benzene-1,2-dicarbaldehydes were synthesized by the reaction of substituted-1,2-bis (dibromomethyl) benzenes with fuming sulfuric acid, followed by hydrolysis, The yields were significantly improved by introducing solid sodium bicarbonate into the reaction mixture before hydrolysis and workup.

  11. An efficient synthesis of substituted benzene-1,2-dicarboxaldehydes

    Institute of Scientific and Technical Information of China (English)

    ZHU; Peter; C; WANG; Der-Haw; MANI; Neelakandha


    Substituted-benzene-1,2-dicarbaldehydes were synthesized by the reaction of substituted-1,2-bis(dibromomethyl) benzenes with fuming sulfuric acid,followed by hydrolysis. The yields were signifi-cantly improved by introducing solid sodium bicarbonate into the reaction mixture before hydrolysis and workup.

  12. Benzene as a Chemical Hazard in Processed Foods (United States)

    Salviano dos Santos, Vânia Paula; Medeiros Salgado, Andréa; Guedes Torres, Alexandre; Signori Pereira, Karen


    This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer) as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1–10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food. PMID:26904662

  13. Benzene as a Chemical Hazard in Processed Foods

    Directory of Open Access Journals (Sweden)

    Vânia Paula Salviano dos Santos


    Full Text Available This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1–10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food.

  14. [Benzene in soft drinks: a study in Florence (Italy)]. (United States)

    Bonaccorsi, Guglielmo; Perico, Andrea; Colzi, Alessio; Bavazzano, Paolo; Di Giusto, Maurizio; Lamberti, Ilaria; Martino, Gianrocco; Puggelli, Francesco; Lorini, Chiara


    The aim of this study was to determine the amount of benzene present in soft drinks sold in Florence (Italy). We analyzed 28 different types of soft drinks, by measuring concentrations of benzoic acid, sorbic acid, ascorbic acid (using high performance liquid chromatography with UV detection) and benzene (using gas chromatography and mass spectrometry). Data was analysed by using SPSS 18.0.Traces of benzene were detected in all analyzed beverages, with a mean concentration of 0.45 µg/L (range: 0.15-2.36 µg/L). Statistically significant differences in mean benzene concentrations were found between beverages according to the type of additive indicated on the drink label, with higher concentrations found in beverages containing both ascorbic acid and sodium benzoate. Two citrus fruit-based drinks were found to have benzene levels above the European limit for benzene in drinking water of 1 µg /L. Sodium benzoate and ascorbic acid were also detected in the two drinks.In conclusion, not all soft drink producers have taken steps to eliminate benzoic acid from their soft drinks and thereby reduce the risk of formation of benzene, as recommended by the European Commission. Furthermore, the presence of benzene in trace amounts in all beverages suggests that migration of constituents of plastic packaging materials or air-borne contamination may be occurring.

  15. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin


    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  16. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin


    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  17. Anaerobic degradation of benzene by marine sulfate-reducing bacteria (United States)

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


    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

  18. Urinary t,t-muconic acid, S-phenylmercapturic acid and benzene as biomarkers of low benzene exposure. (United States)

    Fustinoni, Silvia; Buratti, Marina; Campo, Laura; Colombi, Antonio; Consonni, Dario; Pesatori, Angela C; Bonzini, Matteo; Farmer, Peter; Garte, Seymour; Valerio, Federico; Merlo, Domenico F; Bertazzi, Pier A


    This research compared the capability of urinary trans,trans-muconic acid (t,t-MA), S-phenylmercapturic acid (S-PMA) and benzene excreted in urine (U-benzene) to monitor low benzene exposure and evaluated the influence of smoking habit on these indices. Gasoline attendants, urban policemen, bus drivers and two groups of referents working in two large Italian cities (415 people) were studied. Median benzene exposure was 61, 22, 21, 9 and 6 microg/m3, respectively, with higher levels in workers than in referents. U-benzene, but not t,t-MA and S-PMA, showed an exposure-related increase. All the biomarkers were strongly influenced by cigarette smoking, with values up to five-fold higher in smokers compared to non-smokers. In conclusion, in the range of investigated benzene exposure (<478 microg/m3 or <0.15 ppm), the smoking habit may be regarded as a major source of benzene intake; among the study indices, U-benzene is the marker of choice for the biological monitoring of occupational and environmental exposure.

  19. Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC (United States)

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


    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.

  20. A Quantum Monte Carlo Study of mono(benzene)TM and bis(benzene)TM Systems

    CERN Document Server

    Bennett, M Chandler; Mitas, Lubos


    We present a study of mono(benzene)TM and bis(benzene)TM systems, where TM={Mo,W}. We calculate the binding energies by quantum Monte Carlo (QMC) approaches and compare the results with other methods and available experiments. The orbitals for the determinantal part of each trial wave function were generated from several types of DFT in order to optimize for fixed-node errors. We estimate and compare the size of the fixed-node errors for both the Mo and W systems with regard to the electron density and degree of localization in these systems. For the W systems we provide benchmarking results of the binding energies, given that experimental data is not available.

  1. A quantum Monte Carlo study of mono(benzene) TM and bis(benzene) TM systems (United States)

    Bennett, M. Chandler; Kulahlioglu, A. H.; Mitas, L.


    We present a study of mono(benzene) TM and bis(benzene) TM systems, where TM = {Mo, W}. We calculate the binding energies by quantum Monte Carlo (QMC) approaches and compare the results with other methods and available experiments. The orbitals for the determinantal part of each trial wave function were generated from several types of DFT functionals in order to optimize for fixed-node errors. We estimate and compare the size of the fixed-node errors for both the Mo and W systems with regard to the electron density and degree of localization in these systems. For the W systems we provide benchmarking results of the binding energies, given that experimental data is not available.

  2. New routes lead to benzene, propanal

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Haggin


    An ongoing research program at Oxford University in England has resulted in two new schemes for direct catalytic conversion of methane. One scheme produces aromatics, principally benzene, by oligomerization. The second scheme produces propanal in high yield by the judicious combination of three catalytic processes that have all been used before. One of the most active research areas is the catalytic conversion of methane to methanol, but so far the best yield has been about 8%, much too low for commercial interest. Likewise, the direct catalytic conversion of methane to ethane and/or ethylene has yet to produce either yields or selectivities high enough to compete with these products from crude oil. The paper describes these two new processes and their improved yields.

  3. Benzene conversion by manganese dioxide assisted silent discharge plasma

    Institute of Scientific and Technical Information of China (English)

    LU Bin; JI Min; YU Xin; FENG Tao; YAO Shuiliang


    Non-thermal plasma technologies have shown their promising potential specially for the low concentration of volatile organic compound control in indoor air in recent years.But it is also high energy consuming.So,to improve the energy efficiency,adding catalysts which enhance the plasma chemical reactions to plasma reactors may be a good selection.Therefore,in this study the manganese dioxide assisted silent discharge plasma was developed for benzene conversion at a relatively high energy efficiency.The results show that MnO2 could promote complete oxidation of benzene with O2 and O3 produced in the plasma discharge zone.The energy efficiency of benzene conversion with MnO2 was two folds as much as that without catalysts.It was also found that the site of MnO2 in the reactor and the energy density had effects on benzene conversion.While the energy density was lower than 48 J/L,benzene conversion decreased with the increase in the distance between MnO2 bed and the plasma discharge zone.Whereas when the energy density was higher than 104 J/L,benzene conversion had an optimal value that was governed by the distance between MnO2 bed and the plasma discharge zone.The mechanism of benzene oxidation in plasma discharges and over MnO2 is discussed in detail.

  4. Benzene removal by a novel modification of enhanced anaerobic biostimulation. (United States)

    Xiong, Wenhui; Mathies, Chris; Bradshaw, Kris; Carlson, Trevor; Tang, Kimberley; Wang, Yi


    A novel modification of enhanced anaerobic bioremediation techniques was developed by using non-activated persulfate to accelerate the organic phosphorus breakdown and then stimulate benzene biodegradation by nitrate and sulfate reduction. Benzene concentrations in groundwater where nitrate, triethyl phosphate and persulfate were successfully injected were reduced at removal efficiencies greater than 77% to the levels below the applicable guideline. Soil benzene was removed effectively by the modification of the enhanced anaerobic bioremediation with removal efficiencies ranging between 75.9% and 92.8%. Geochemical analytical results indicated that persulfate effectively breaks down triethyl phosphate into orthophosphate, thereby promoting nitrate and sulfate utilization. Microbial analyses (quantitative polymerase chain reaction, denaturing gradient gel electrophoresis and 16S ribosomal RNA) demonstrated that benzene was primarily biodegraded by nitrate reduction while sulfate reduction played an important role in benzene removal at some portions of the study site. Enrichment in the heavier carbon isotope ¹³C of residual benzene with the increased removal efficiency provided direct evidence for benzene biodegradation. Nitrogen, sulfur and oxygen isotope analyses indicated that both nitrate reduction and sulfate reduction were occurring as bioremediation mechanisms.

  5. Aryl hydrocarbon receptor mediates benzene-induced hematotoxicity. (United States)

    Yoon, Byung-Il; Hirabayashi, Yoko; Kawasaki, Yasushi; Kodama, Yukio; Kaneko, Toyozo; Kanno, Jun; Kim, Dae-Yong; Fujii-Kuriyama, Yoshiaki; Inoue, Tohru


    Benzene can induce hematotoxicity and leukemia in humans and mice. Since a review of the literature shows that the CYP2E1 knockout mouse is not known to possess any benzene toxicity, the metabolism of benzene by CYP2E1 in the liver is regarded to be prerequisite for its cytotoxicity and genotoxicity, although the mechanism is not fully understood yet. Because it was found some years ago that benzene was also a substrate for CYP1A1, we investigated the involvement of the aryl hydrocarbon receptor (AhR) in benzene hematotoxicity using AhR wild-type (AhR(+/+)), heterozygous (AhR(+/-)), and homozygous (AhR(-/-)) male mice. Interestingly, following a 2-week inhalation of 300 ppm benzene (a potent dose for leukemogenicity), no hematotoxicity was induced in AhR(-/-) mice. Further, there were no changes in cellularity of peripheral blood and bone marrow (BM), nor in levels of granulocyte-macrophage colony-forming units in BM. This lack of hematotoxicity was associated with the lack of p21 overexpression, which was regularly seen in the wild-type mice following benzene inhalation. Combined treatment with two major benzene metabolites, phenol and hydroquinone, induced hemopoietic toxicity, although it was not known whether this happened due to a surprising lack of expression of CYP2E1 by AhR knockout, or due to a lack of other AhR-mediated CYP enzymes, including 1A1 (i.e., a possible alternative pathway of benzene metabolism). The former possibility, evaluated in the present study, failed to show a significant relationship between AhR and the expression of CYP2E1. Furthermore, a subsequent evaluation of AhR expression after benzene inhalation tended to show higher but less significant expression in the liver, and none in the BM, compared with sham control. Although this study failed to identify the more likely of the above-mentioned two possibilities, the study using AhR knockout mice on benzene inhalation presents the unique possibility that the benzene toxicity may be

  6. Association between genetic variants in VEGF, ERCC3 and occupational benzene haematotoxicity.

    NARCIS (Netherlands)

    Hosgood 3rd, H.D.; Zhang, L.; Shen, M.; Berndt, S.I.; Vermeulen, R.; Li, G.; Yin, S.; Yeager, M.; Yuenger, J.; Rothman, N.; Chanock, S.; Smith, M.; Lan, Q.


    INTRODUCTION: Benzene is an established human haematotoxin, with substantial interindividual variation in benzene-induced toxicity. METHODS: To further examine if genetic variation contributes to benzene haematotoxicity, we analysed 1023 tagSNPs in 121 gene regions important for benzene metabolism,

  7. Intrinsic and enhanced biodegradation of benzene in strongly reduced aquifers

    NARCIS (Netherlands)

    Heiningen, W.N.M. van; Rijnaarts, H.H.M; Langenhoff, A.A.M.


    Laboratory microcosm studies were performed to examine intrinsic and enhanced benzene bioremediation using five different sediment and groundwater samples from three deeply anaerobic aquifers sited in northern Netherlands. The influence of addition of nitrate, sulfate, limited amounts of oxygen, and

  8. Magnetically rotational reactor for absorbing benzene emissions by ionic liquids

    Institute of Scientific and Technical Information of China (English)

    Yangyang; Jiang; Chen; Guo; Huizhou; Liu


    A magnetically rotational reactor (MRR) has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/ghigher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet.

  9. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others


    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  10. Non-Collinearity in Small Magnetic Cobalt-Benzene Molecules

    CERN Document Server

    González, J W; Delgado, F; Aguilera-Granja, F; Ayuela, A


    Cobalt clusters covered with benzene in the form of rice-ball structures have recently been synthesized using laser ablation. Here, we investigate the types of magnetic order such clusters have, and whether they retain any magnetic order at all. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings. We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. This is surprising because nanostructures and small clusters based on pure cobalt typically have a predominantly ferromagnetic order, and additional organic ligands such as benzene tend to remove the magnetization. We analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. Moreover, we propose electron paramagnetic resonance as ...

  11. Enhanced π-frustration in carbo-benzenic chromophores. (United States)

    Baglai, Iaroslav; Maraval, Valérie; Bijani, Christian; Saffon-Merceron, Nathalie; Voitenko, Zoia; Volovenko, Yulian M; Chauvin, Remi


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

  12. Positronium quenching in liquid and solid octanol and benzene

    DEFF Research Database (Denmark)

    Shantarovich, V.P.; Mogensen, O.E.; Goldanskii, V.I.


    The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase....

  13. Which ornamental plant species effectively remove benzene from indoor air? (United States)

    Liu, Yan-Ju; Mu, Yu-Jing; Zhu, Yong-Guan; Ding, Hui; Crystal Arens, Nan

    Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.

  14. Organometallic chemistry using partially fluorinated benzenes. (United States)

    Pike, Sebastian D; Crimmin, Mark R; Chaplin, Adrian B


    Fluorobenzenes, in particular fluorobenzene (FB) and 1,2-difluorobenzene (1,2-DiFB), are increasingly becoming recognised as versatile solvents for conducting organometallic chemistry and transition-metal-based catalysis. The presence of fluorine substituents reduces the ability to donate π-electron density from the arene and consequently fluorobenzenes generally bind weakly to metal centres, allowing them to be used as essentially non-coordinating solvents or as readily displaced ligands. In this context, examples of well-defined complexes of fluorobenzenes are discussed, including trends in binding strength with increasing fluorination and different substitution patterns. Compared to more highly fluorinated benzenes, FB and 1,2-DiFB typically demonstrate greater chemical inertness, however, C-H and C-F bond activation reactions can be induced using appropriately reactive transition metal complexes. Such reactions are surveyed, including catalytic examples, not only to provide perspective for the use of FB and 1,2-DiFB as innocent solvent media, but also to highlight opportunities for their exploitation in contemporary organic synthesis.

  15. Spectroscopic studies of cryogenic fluids: Benzene in argon and helium (United States)

    Nowak, R.; Bernstein, E. R.


    Energy shifts and bandwidths of the 610 vibronic feature of the 1B2u←1A1g optical absorption spectrum of benzene dissolved in supercritical argon and helium, and in liquid argon are reported as a function of pressure, temperature, and density. Benzene/Ar solutions display red shifts of the 610 transition with increasing density but the dependence is found to be nonlinear at high densities. Benzene/He solutions evidence blue shifts of the 610 transition as a function of increasing density which also becomes nonlinear at high densities. Only small spectral shifts are recorded if the density is kept constant and pressure and temperature are varied simultaneously. In addition, a small density independent temperature effect on the transition energy shift is identified. Experimental results are compared to dielectric (Onsager-Böttcher and Wertheim) and quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute absorption energy. Reasonably good agreement between experiment and theory is found only for the benzene/Ar system at relatively low densities. The theory fails to predict energy shifts for both the benzene/He and high density benzene/Ar systems. This result is different from the findings for the benzene/N2 and benzene/C3H8 solutions and can be interpreted qualitatively in terms of competition between dispersive attractive and repulsive interactions as a function of density. The failure of the theory to describe these transition energy shifts is attributed to the omission of explicit repulsive interactions terms in the theoretical models employed.

  16. Can Cooper pairs in benzene lead to Efimov states? (United States)

    Squire, R. H.; March, N. H.; Rubio, A.


    Cooper pairs have been experimentally verified in benzene at 38.3 eV. We have proposed previously that the six most loosely bound electrons in benzene form three equivalent Cooper pairs. We further propose in this manuscript that these three weakly interacting bosons (Cooper pairs) should form an infinite number of Efimov states (possibly Booromean rings) which is what a photon of high energy will then encounter.

  17. Chemical accuracy from quantum Monte Carlo for the Benzene Dimer


    Azadi, Sam; Cohen, R. E


    We report an accurate study of interactions between Benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory (DFT) using different van der Waals (vdW) functionals. In our QMC calculations, we use accurate correlated trial wave functions including three-body Jastrow factors, and backflow transformations. We consider two benzene molecules in the parallel displaced (PD) geometry, and fin...

  18. Cultivating microbial dark matter in benzene-degrading methanogenic consortia. (United States)

    Luo, Fei; Devine, Cheryl E; Edwards, Elizabeth A


    The microbes responsible for anaerobic benzene biodegradation remain poorly characterized. In this study, we identified and quantified microbial populations in a series of 16 distinct methanogenic, benzene-degrading enrichment cultures using a combination of traditional 16S rRNA clone libraries (four cultures), pyrotag 16S rRNA amplicon sequencing (11 cultures), metagenome sequencing (1 culture) and quantitative polymerase chain reaction (qPCR; 12 cultures). An operational taxonomic unit (OTU) from the Deltaproteobacteria designated ORM2 that is only 84% to 86% similar to Syntrophus or Desulfobacterium spp. was consistently identified in all enrichment cultures, and typically comprised more than half of the bacterial sequences. In addition to ORM2, a sequence belonging to Parcubacteria (candidate division OD1) identified from the metagenome data was the only other OTU common to all the cultures surveyed. Culture transfers (1% and 0.1%) were made in the presence and absence of benzene, and the abundance of ORM2, OD1 and other OTUs was tracked over 415 days using qPCR. ORM2 sequence abundance increased only when benzene was present, while the abundance of OD1 and other OTUs increased even in the absence of benzene. Deltaproteobacterium ORM2 is unequivocally the benzene-metabolizing population. This study also hints at laboratory cultivation conditions for a member of the widely distributed yet uncultivated Parcubacteria (OD1).

  19. Products of the Benzene + O(3P) Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Meloni, Giovanni; Trevitt, Adam J.; Epifanovsky, Evgeny; Krylov, Anna I.; Sirjean, Baptiste; Dames, Enoch; Wang, Hai


    The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to 10 Torr. The reactions were initiated by pulsed-laser photolysis of NO2 in the presence of benzene and helium buffer in a slow-flow reactor, and reaction products were identified by using the multiplexed chemical kinetics photoionization mass spectrometer operating at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory. Phenol and phenoxy radical were detected and quantified. Cyclopentadiene and cyclopentadienyl radical were directly identified for the first time. Finally, ab initio calculations and master equation/RRKM modeling were used to reproduce the experimental branching ratios, yielding pressure-dependent rate expressions for the reaction channels, including phenoxy + H, phenol, cyclopentadiene + CO, which are proposed for kinetic modeling of benzene oxidation.

  20. Genotoxicity of intermittent co-exposure to benzene and toluene in male CD-1 mice. (United States)

    Wetmore, Barbara A; Struve, Melanie F; Gao, Pu; Sharma, Sheela; Allison, Neil; Roberts, Kay C; Letinski, Daniel J; Nicolich, Mark J; Bird, Michael G; Dorman, David C


    Benzene is an important industrial chemical. At certain levels, benzene has been found to produce aplastic anemia, pancytopenia, myeloblastic anemia and genotoxic effects in humans. Metabolism by cytochrome P450 monooxygenases and myeloperoxidase to hydroquinone, phenol, and other metabolites contributes to benzene toxicity. Other xenobiotic substrates for cytochrome P450 can alter benzene metabolism. At high concentrations, toluene has been shown to inhibit benzene metabolism and benzene-induced toxicities. The present study investigated the genotoxicity of exposure to benzene and toluene at lower and intermittent co-exposures. Mice were exposed via whole-body inhalation for 6h/day for 8 days (over a 15-day time period) to air, 50 ppm benzene, 100 ppm toluene, 50 ppm benzene and 50 ppm toluene, or 50 ppm benzene and 100 ppm toluene. Mice exposed to 50 ppm benzene exhibited an increased frequency (2.4-fold) of micronucleated polychromatic erythrocytes (PCE) and increased levels of urinary metabolites (t,t-muconic acid, hydroquinone, and s-phenylmercapturic acid) vs. air-exposed controls. Benzene co-exposure with 100 ppm toluene resulted in similar urinary metabolite levels but a 3.7-fold increase in frequency of micronucleated PCE. Benzene co-exposure with 50 ppm toluene resulted in a similar elevation of micronuclei frequency as with 100 ppm toluene which did not differ significantly from 50 ppm benzene exposure alone. Both co-exposures - 50 ppm benzene with 50 or 100 ppm toluene - resulted in significantly elevated CYP2E1 activities that did not occur following benzene or toluene exposure alone. Whole blood glutathione (GSH) levels were similarly decreased following exposure to 50 ppm benzene and/or 100 ppm toluene, while co-exposure to 50 ppm benzene and 100 ppm toluene significantly decreased GSSG levels and increased the GSH/GSSG ratio. The higher frequency of micronucleated PCE following benzene and toluene co-exposure when compared with mice exposed to

  1. 1-[(3-Benzyloxy-2-nitrophenoxymethyl]benzene

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun


    Full Text Available The asymmetric unit of the title compound, C20H17NO4, consists of two crystallographically independent molecules. In one of the molecules, the central benzene ring forms dihedral angles of 2.26 (6 and 58.68 (6° with the terminal benzene rings and the dihedral angle between the terminal benzene rings is 56.45 (6°. The corresponding values for the other molecule are 35.17 (6, 70.97 (6 and 69.62 (6°, respectively. In the crystal, an inversion dimer linked by a pair of C—H...O hydrogen bonds occurs for one of the unique molecules. C—H...π and π–π [centroid–centroid distances = 3.7113 (8 and 3.7216 (7 Å] interactions link the components into a three-dimensional network.

  2. Retrospective exposure assessment for benzene in the Australian petroleum industry

    Energy Technology Data Exchange (ETDEWEB)

    Glass, D.C. [Deakin Univ., Occupational Hygiene Unit, Geelong, VIC (Australia); Melbourne Univ., Dept. of Public Health and Community Medicine, Carlton, VIC (Australia); Adams, G.G.; Manuell, R.W.; Bisby, J.A. [Melbourne Univ., Dept. of Public Health and Community Medicine, Carlton, VIC (Australia)


    An excess of lympho-haematopoietic (LH) cancers has been identified in the Australian petroleum industry through the Health Watch surveillance programme. A nested case-control study is being conducted to investigate this excess. This paper describes the methods used to provide quantitative estimates of benzene exposure for each of the subjects in the case-control study. Job histories were compiled for each subject from interviews and company employment records. Site visits and telephone interviews were used to identify the tasks included in each job title. Details about the tasks such as their frequency, the technology in use and about changes that had taken place over the years were also gathered. Exposure dated back to the late 1940s for a few subjects. Collaborating petroleum companies provided recent benzene exposure monitoring data. These were used to generate Base Estimates of exposure for each task, augmented with data from the literature where necessary. Past exposures were estimated from the Base Estimates by means of an exposure algorithm. The modifying effects of technological changes and changes to the product were used in the algorithm. The algorithm was then computed to give, for each job, for each subject, an estimate of average benzene exposure in ppm in the workplace atmosphere (Workplace Estimate). This value was multiplied by the years for which the job was held and these values summed to give an estimate of Cumulative Estimate of benzene in ppm-years. The occupational hygienists performing the exposure assessment did so without knowledge of the case or control status of subjects. Overall exposures to benzene in the Australian petroleum industry were low, and virtually all activities and jobs were below a time-weighted average of 5 ppm. Exposures in terminals were generally higher than at refineries. Exposures in upstream areas were extremely low. Estimates of Cumulative Estimate to benzene ranged from 0.005 to 50.9 ppm-years. (Author)

  3. Solubilization of benzene and cyclohexane by sodium deoxycholate micelles

    Energy Technology Data Exchange (ETDEWEB)

    Christian, S.D.; Smith, L.S.; Bushong, D.S.; Tucker, E.E.


    Vapor pressure-solubility data were obtained for the aqueous systems benzene-sodium deoxycholate and cyclohexane- sodium deoxycholate at 25/sup 0/C. The results are consistent with a mass action model similar to the BET equation. Equilibrium constants are inferred to characterize interactions of hydrocarbons with solubilization sites assumed to consist of units of four deoxycholate anions. Although addition of sodium chloride increases the middle aggregation number, solubilization results are affected very little by variation in salt concentration. When pure liquid hydrocarbon standard states are employed, solubilization results for benzene and cyclohexane (at varying salt concentrations) are quite similar. 26 references.

  4. Characterization of changes in gene expression and biochemical pathways at low levels of benzene exposure

    NARCIS (Netherlands)

    Thomas, Reuben; Hubbard, Alan E.; McHale, Cliona M.; Zhang, Luoping; Rappaport, Stephen M.; Lan, Qing; Rothman, Nathaniel; Vermeulen, Roel; Guyton, Kathryn Z.; Jinot, Jennifer; Sonawane, Babasaheb R.; Smith, Martyn T.


    Benzene, a ubiquitous environmental pollutant, causes acute myeloid leukemia (AML). Recently, through transcriptome profiling of peripheral blood mononuclear cells (PBMC), we reported dose-dependent effects of benzene exposure on gene expression and biochemical pathways in 83 workers exposed across

  5. Metagenomic and proteomic analyses to elucidate the mechanism of anaerobic benzene degradation

    Energy Technology Data Exchange (ETDEWEB)

    Abu Laban, Nidal [Helmholtz (Germany)


    This paper presents the mechanism of anaerobic benzene degradation using metagenomic and proteomic analyses. The objective of the study is to find out the microbes and biochemistry involved in benzene degradation. Hypotheses are proposed for the initial activation mechanism of benzene under anaerobic conditions. Two methods for degradation, molecular characterization and identification of benzene-degrading enzymes, are described. The physiological and molecular characteristics of iron-reducing enrichment culture are given and the process is detailed. Metagenome analysis of iron-reducing culture is presented using a pie chart. From the metagenome analysis of benzene-degrading culture, putative mobile element genes were identified in the aromatic-degrading configurations. Metaproteomic analysis of iron-reducing cultures and the anaerobic benzene degradation pathway are also elucidated. From the study, it can be concluded that gram-positive bacteria are involved in benzene degradation under iron-reducing conditions and that the catalysis mechanism of putative anaerobic benzene carboxylase needs further investigation.

  6. Are there Efimov trimers in hexafluorobenzene rather than in benzene vapor itself?

    Energy Technology Data Exchange (ETDEWEB)

    Squire, R.H., E-mail: [Department of Natural Sciences, West Virginia University – Institute of Technology, Montgomery, WV 25136 (United States); March, N.H. [Department of Physics, University of Antwerp, Groenborgerlaan 171, B-2020, Antwerp (Belgium); Oxford University, Oxford, England (United Kingdom); Abdus Salam International Center for Theoretical Physics, Trieste (Italy)


    Is there a spectroscopic method to detect an Efimov state? Following our proposal of an Efimov state arising from three pseudo bosons (generalized Cooper pairs) in benzene, our spectroscopic studies have found no evidence of Efimov trimers (ET) in h{sub 6}- or d{sub 6}-benzene. However, hexafluoro-benzene has shown peaks that we attributed to ET and the pseudo bosons. The experimental evidence suggests that benzene pseudo bosons and subsequently ET are quite sensitive to the surroundings.

  7. Theoretical study of the solvent effect on the aromaticity of benzene: a NICS analysis. (United States)

    Junqueira, Georgia M A; Dos Santos, Hélio F


    Nucleus-independent chemical shift (NICS) quantities for benzene-benzene and benzene-water species were obtained and are discussed in gas phase and in solution. Besides standard polarizable continuum model (PCM) calculations, sequential Monte Carlo/quantum mechanics (S-MC/QM) were also performed. Benzene was shown to be slightly more aromatic in condensate phase when we considered the average solvent configuration (ASEC) approach with explicit molecules.

  8. Instrument for benzene and toluene emission measurements of glycol regenerators (United States)

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


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

  9. Spectroscopic studies of cryogenic fluids: Benzene in nitrogen (United States)

    Nowak, R.; Bernstein, E. R.


    Energy shifts and bandwidths for the 1B2u←1A1g optical absorption of benzene in supercritical nitrogen are presented as a function of pressure, temperature, and density. The pressure and density dependence of energy shifts of room temperature emission of benzene in nitrogen fluid is also reported. Both absorption and emission spectra exhibit shifts to lower energy as a function of density, whereas almost no spectral shifts are observed if the density is kept constant and temperature and pressure varied simultaneously. Thus, density is the fundamental microscopic parameter for energy shifts of optical transitions in supercritical nitrogen. This result is analogous to the findings for the liquid benzene/propane system and can be interpreted qualitatively in terms of changes occurring in the intermolecular potential; however, in the benzene/supercritical nitrogen system an additional small density independent temperature effect on the transition energy has been identified. Experimental results are compared to dielectric (Onsager-Böttcher and Wertheim) and microscopic quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute electronic spectra. Reasonably good agreement between experiment and theory is found. The results demonstrate that liquid state theory can be used to describe the supercritical nitrogen fluid.

  10. Degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria

    NARCIS (Netherlands)

    Weelink, S.A.B.


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

  11. 1,4-Bis[3-chloro-2-(chloromethylpropyl]benzene

    Directory of Open Access Journals (Sweden)


    Full Text Available The title molecule, C14H18Cl4, possesses a crystallographically imposed inversion centre, which coincides with the centre of benzene ring. In the absence of classical intermolecular interactions, van der Waals forces help the molecules to pack in the crystal.

  12. Effects of benzene inhalation on murine pluripotent stem cells. (United States)

    Cronkite, E P; Inoue, T; Carsten, A L; Miller, M E; Bullis, J E; Drew, R T


    Effects of benzene inhalation on mouse pluripotent hematopoietic stem cells have been evaluated. Male mice 8--12 wk old were exposed to 400 ppm benzene for 6 h/d, 5 d/wk, for up to 9 1/2 wk. At various time intervals exposed and control animals were killed, and cardiac blood was evaluated for changes in white blood cell (WBC) and red blood cell (RBC) content. In addition, femora and tibiae were evaluated for total marrow cellularity, stem cell content (as measured by the spleen colony technique), and the percent of stem cells in DNA synthesis (as determined by the tritiated thymidine cytocide technique). Exogenous spleen colonies grown from marrow of exposed animals were counted, identified, and scored by histological type. Exposure to benzene caused significant depressions of RBCs and WBCs throughout the exposure period, which continued for at least 14 d after exposure. Bone marrow cellularity and stem cell content were also depressed in exposed animals throughout the study. Tritiated thymidine cytocide of spleen colony-forming cells was generally increased in exposed animals, perhaps indicating a compensatory response to the reduction of circulating cells. Spleen colonies of all types were depressed after exposure to benzene. The significance of the reduction in cellularity, stem cell content, and changes in morphology of spleen colonies is discussed in relation to cellular toxicity and residual injury.

  13. The ototoxic effects of ethyl benzene in rats

    NARCIS (Netherlands)

    Cappaert, N.L.M.; Klis, S.F.L.; Muijser, H.; Groot, J.C.M.J. de; Kulig, B.M.; Smoorenburg, G.F.


    Exposure to organic solvents has been shown to be ototoxic in animals and there is evidence that these solvents can induce hearing loss in humans. In this study, the effects of inhalation of the possibly ototoxic solvent ethyl benzene on the cochlear function and morphology were evaluated using thre

  14. Benzene Removal by Iron Oxide Nanoparticles Decorated Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Aamir Abbas


    Full Text Available In this paper, carbon nanotubes (CNTs impregnated with iron oxide nanoparticles were employed for the removal of benzene from water. The adsorbents were characterized using scanning electron microscope, X-ray diffraction, BET surface area, and thermogravimetric analysis. Batch adsorption experiments were carried out to study the adsorptive removal of benzene and the effect of parameters such as pH, contact time, and adsorbent dosage. The maximum removal of benzene was 61% with iron oxide impregnated CNTs at an adsorbent dosage 100 mg, shaking speed 200 rpm, contact time 2 hours, initial concentration 1 ppm, and pH 6. However, raw CNTs showed only 53% removal under same experimental conditions. Pseudo-first-order kinetic model was found well to describe the obtained data on benzene removal from water. Initial concentration was varied from 1 to 200 mg/L for isotherms study. Langmuir isotherm model was observed to best describe the adsorption data. The maximum adsorption capacities were 987.58 mg/g and 517.27 mg/g for iron oxide impregnated CNTs and raw CNTs, respectively. Experimental results revealed that impregnation with iron oxide nanoparticles significantly increased the removal efficiency of CNTs.

  15. Biotransformation of toluene, benzene and naphthalene under anaerobic conditions.

    NARCIS (Netherlands)

    Langenhoff, A.A.M.


    Aromatic hydrocarbons are widespread in nature, due to increasing industrial activity, and often contribute to polluted soils, sediments, and groundwater. Most of these compounds are toxic at relatively high concentrations, but some are already carcinogenic at very low concentrations, e.g. benzene.

  16. Electronic states of 1,4-bis(phenylethynyl)benzene

    DEFF Research Database (Denmark)

    Nguyen, Duy Duc; Jones, Nykola; Hoffmann, Søren Vrønning


    The electronic transitions of 1,4-bis(phenylethynyl)benzene (BPEB) were investigated by UV synchrotron radiation linear dichroism (SRLD) spectroscopy in the range 25,000 – 58,000 cm–1 (400 – 170 nm) on molecular samples aligned in stretched polyethylene. The investigation was supported by variable...

  17. Development of microbial engineered whole-cell systems for environmental benzene determination. (United States)

    Di Gennaro, P; Bruzzese, N; Anderlini, D; Aiossa, M; Papacchini, M; Campanella, L; Bestetti, G


    This paper reports the development of two recombinant bacterial systems that can be used to monitor environmental benzene contamination based on Escherichia coli, which carry genes coding for benzene dioxygenase and benzene dihydrodiol dehydrogenase from Pseudomonas putida MST. E. coli strains express these two enzymes under the control of the Ptac promoter or without any induction. These activities can be detected electrochemically or colorimetrically and used to monitor benzene pollution in environmental air samples collected from an oil refinery assessing benzene by different laboratory experimental procedures. The procedures involving whole-cell bioassays determine the concentration of benzene through benzene dioxygenase activity, which allows for direct correlation of oxygen consumption, and through the benzene dihydrodiol dehydrogenase that causes catechol accumulation and restores NADH necessary for the activity of the first enzyme. Oxygen consumption and catechol production deriving from both enzymatic activities are related to benzene concentration and their measurements determined the sensitivity of the system. The results indicated that the sensitivity was enough to detect the benzene vapor at a lower concentration level of 0.01 mM in about 30 min. The possibility for on-line monitoring of benzene concentration by our new recombinant cells results from the fact that no particular treatment of environmental samples is required. This is a major advantage over other biosensors or assays. Moreover, the development of microbial cells that did not require any addition or effectors for the transcription of the specific enzymes, allowed these systems to be more versatile in automated environmental benzene monitoring.

  18. Toxicogenomic analysis of gene expression changes in rat liver after a 28-day oral benzene exposure

    NARCIS (Netherlands)

    Heijne, W.H.M.; Jonker, D.; Stierum, R.H.; Ommen, B. van; Groten, J.P.


    Benzene is an industrial chemical, component of automobile exhaust and cigarette smoke. After hepatic bioactivation benzene induces bone marrow, blood and hepatic toxicity. Using a toxicogenomics approach this study analysed the effects of benzene at three dose levels on gene expression in the liver

  19. Quantum Monte Carlo Study of π-Bonded Transition Metal Organometallics: Neutral and Cationic Vanadium-Benzene and Cobalt-Benzene Half Sandwiches. (United States)

    Horváthová, L; Dubecký, M; Mitas, L; Štich, I


    We present accurate quantum Monte Carlo (QMC) calculations that enabled us to determine the structure, spin multiplicity, ionization energy, dissociation energy, and spin-dependent electronic gaps of neutral and positively charged vanadium-benzene and cobalt-benzene systems. From total/ionization energy, we deduce a sextet (quintet) state of neutral (cationic) vanadium-benzene systems and quartet (triplet) state of the neutral (cationic) cobalt-benzene systems. Vastly different energy gaps for the two spin channels are predicted for the vanadium-benzene system and broadly similar energy gaps for the cobalt-benzene system. For this purpose, we have used a multistage combination of techniques with consecutive elimination of systematic biases except for the fixed-node approximation in QMC. Our results significantly differ from the established picture based on previous less accurate calculations and point out the importance of high-level many-body methods for predictive calculations of similar transition metal-based organometallic systems.

  20. Supplementary measurements for air monitoring under NOVANA - Benzene and PAH; Supplerende maalinger til luftovervaagning under NOVANA - benzen og PAH

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Klenoe Noejgaard, J.; Bossi, R.


    The report presents results from a project carried out for the Danish Environmental Protection Agency. The aim of the project was to carry out several measuring campaigns in order to be able to better assess the monitoring needs for PAH and benzene in relation to EU's air quality directives. The results show that the mean concentrations of benzene are almost at the same level in Denmark's four largest cities, and that the concentrations are both below the threshold value (5mug/m3) as well as below the lower assessment threshold (2mug/m3). The report presents a method for objectively estimation the benzene concentration based on measurements of CO. The method can be applied to fulfil the monitoring need for benzene in those zones where no measurements of benzene are made. Measurements of PAH, especially benzo(a)pyrene, have been made during 12 months in the period 2010-2011 in an area with many wood burning furnaces are used (the town Jyllinge). The concentrations of benzo(a)pyrene in Jyllinge is almost three times higher than in the street H.C. Andersens Boulevard in Copenhagen. The concentrations of benzo(a)pyrene in Jylllinge are 0,6 ng/m3, which corresponds to the upper assessment threshold (0,6 ng/m3) and is 40% below the measuring value (1 ng/m3). On this basis, there is a need for re-evaluating the monitoring of PAH in the sub-programme for air under NOVANA. Measurements of PM{sub 10} showed that the levels in the towns Jyllinge, Lille Valby/Risoe and at the H.C. Oersted Institute in Copenhagen are all at about 20-22 mug/m3. (LN)

  1. Transport and phase equilibria of benzene in FAU type zeolites (United States)

    Saravanan, Chandra

    We have studied lattice models for self-diffusion of benzene in FAU type zeolites, to explore the effect of the thermodynamics of confined fluids on the transport properties of molecules in zeolites. Our model assumes that benzene molecules are located near Na+ ions in supercages, and in 12-ring windows separating adjacent supercages, respectively. The study was performed in three stages. First, to disentangle the effect of a vapor-liquid phase equilibria on diffusion in zeolites, the transport of benzene in Na-Y is modeled in the absence of attractive guest-guest interactions. The loading dependence of diffusion coefficient, Dtheta, at a constant temperature, referred to as a diffusion isotherm, is modeled with site-blocking effects using a mean field theory (MFT) that yields, Dq=16kq a2q, where atheta ≅ 11 A is the mean intercage jump length and 1/ktheta is the mean supercage residence time. A completely analytical expression is derived to calculate ktheta. The MFT is tested using a mean field approximation (MFA) where ktheta and atheta are calculated from kinetic Monte Carlo simulations yielding excellent qualitative agreement. Further calculations are performed to test MFA by calculating "exact" diffusion coefficients from mean square displacement (MSD) calculations also yielding excellent qualitative agreement. Next, by including guest-guest attractive interactions, we have performed lattice grand canonical Monte Carlo simulations of benzene adsorption in Na-X zeolite to determine whether strongly confined benzene molecules exhibit subcritical properties. We observe a phase transition from low to high density of adsorbed benzene, analogous to vapor-liquid equilibrium, at temperatures as high as 300 K and above. By performing thermodynamic integration to construct the coexistence curve, we obtain a critical point for benzene in Na-X at Tc = 370 +/- 20 K, thetac = 0.45 +/- 0.05 fractional coverage. We suggest that careful adsorption experiments should be

  2. Product formation from thiophene by a mixed bacterial culture. Influence of benzene as growth substrate

    DEFF Research Database (Denmark)

    Rivas, Isabelle Marie; Mosbæk, Hans; Arvin, Erik


    The influence of benzene as a growth substrate on the cometabolic conversion of thiophene was investigated in batch systems with microorganisms originating from an creosote contaminated site. Benzene was shown to stimulate the conversion of thiophene with a first-order rate, during the initial...... phase of transformation. The microorganisms were able to transform thiophene in the absence of benzene at a zero-order rate. Thiophene was converted to five oxidation products, regardless of the presence of benzene. Benzene had no influence on the distribution of these oxidation products. The main...

  3. The Grand Canonical Monte Carlo Simulations of Benzene and Propylene in ITQ-1 Zeolite

    Institute of Scientific and Technical Information of China (English)


    Grand Canonical Monte Carlo (GCMC) simulations have been performed to study the localization and adsorption behavior of benzene and propylene, in purely siliceous MWW zeolite (ITQ-1). By analyzing the locations of benzene and propylene in ITQ-1, it can be deduced that the alkylation of benzene and propylene will mainly happen in 12-MR supercages at the external surface or close to the external surface. The adsorption isotherms of benzene and propylene at 315K and 0~3.5kPa are predicted, and the results for benzene generally coincide with the trend from the experiments of a series of aromatic compounds.

  4. In-situ Investigation of BBr_3/benzene Solution by Fourier Transformation Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    YU Li-li; GAI Li-gang; CUI De-Hang; WANG Qi-long


    By means of the in-situ Fourier transformation infrared spectroscopy(FTIR), the properties of BBr_3/ benzene solution, which is usually used as the reactant and solution to synthesize BN by benzene-thermal method, have been investigated. The results show that there are some side reactions between BBr_3 and benzene: (1) BBr_3 as an electron-deficient molecule reacts with benzene at room temperature; (2) below 100℃, substitution of Br atom for H atom of benzene(ring-H) dominates in BBr_3/benzene solution; (3) cracking of benzene ring occurs at a temperature above 100℃; (4) decomposition of benzene molecules and formation of long-chain aliphatic compounds feature the spectra of BBr_3/benzene solution collected at above 160℃. They are unfavor for BN to form when BBr_3 is excessive in the synthesis of BN by benzene-thermal route. On the basis of the experimental results, a coordination reaction mechanism via a η~2-C_6H_6 binding mode in BBr_3/benzene solution is suggested.

  5. Benzene exposure and the effect of traffic pollution in Copenhagen, Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Skov, H.; Hansen, A.B.; Andersen, H.V.; Loefstroem, P.; Christensen, C.S. [National Environmental Research Inst., Roskilde (Denmark). Dept. of Atmospheric Environment; Lorenzen, G. [Environmental Protection Agency, Copenhagen (Denmark)


    Benzene is a carcinogenic compound, which is emitted from petrol-fuelled cars and thus is found ubiquitous in all cities. As part of the project Monitoring of Atmospheric Concentrations of Benzene in European Towns and Homes (MACBETH) six campaigns were carried out in the Municipality of Copenhagen, Denmark. The campaigns were distributed over 1 year. In each campaign, the personal exposure to benzene of 50 volunteers (non-smokers living in non-smoking families) living and working in Copenhagen was measured. Simultaneously, benzene was measured in their homes and in an urban network distributed over the municipality. The Radiello diffusive sampler was applied to sample 5 days averages of benzene and other hydrocarbons. Comparison of the results with those from a BTX-monitor showed excellent agreement. The exposure and the concentrations in homes and in the urban area were found to be close to log-normal distribution. The annual averages of the geometrical mean values were 5.22, 4.30 and 2.90{mu}gm{sup -3} for personal exposure, home concentrations and urban concentrations, respectively. Two main parameters are controlling the general level of benzene in Copenhagen: firstly, the emission from traffic and secondly, dispersion due to wind speed. The general level of exposure to benzene and home concentrations of benzene were strongly correlated with the outdoor level of benzene, which indicated that traffic is an important source for indoor concentrations of benzene and for the exposure to benzene. (Author)

  6. Benzene-induced hematotoxicity and bone marrow compensation in B6C3F1 mice. (United States)

    Farris, G M; Robinson, S N; Gaido, K W; Wong, B A; Wong, V A; Hahn, W P; Shah, R S


    Long-term inhalation exposure of benzene has been shown to cause hematotoxicity and an increased incidence of acute myelogenous leukemia in humans. The progression of benzene-induced hematotoxicity and the features of the toxicity that may play a major role in the leukemogenesis are not known. We report the hematological consequences of benzene inhalation in B6C3F1 mice exposed to 1, 5, 10, 100, and 200 ppm benzene for 6 hr/day, 5 days/week for 1, 2, 4, or 8 weeks and a recovery group. There were no significant effects on hematopoietic parameters from exposure to 10 ppm benzene or less. Exposure of mice to 100 and 200 ppm benzene reduced the number of total bone marrow cells, progenitor cells, differentiating hematopoietic cells, and most blood parameters. Replication of primitive progenitor cells in the bone marrow was increased during the exposure period as a compensation for the cytotoxicity induced by 100 and 200 ppm benzene. In mice exposed to 200 ppm benzene, the primitive progenitor cells maintained an increased percentage of cells in S-phase through 25 days of recovery compared with controls. The increased replication of primitive progenitor cells in concert with the reported genotoxicity induced by benzene provides the components necessary for producing an increased incidence of lymphoma in mice. Furthermore, we propose this mode of action as a biologically plausible mechanism for benzene-induced leukemia in humans exposed to high concentrations of benzene.

  7. Benzene exposure and the effect of traffic pollution in Copenhagen, Denmark (United States)

    Skov, Henrik; Hansen, Asger B.; Lorenzen, Gitte; Andersen, Helle Vibeke; Løfstrøm, Per; Christensen, Carsten S.

    Benzene is a carcinogenic compound, which is emitted from petrol-fuelled cars and thus is found ubiquitous in all cities. As part of the project Monitoring of Atmospheric Concentrations of Benzene in European Towns and Homes (MACBETH) six campaigns were carried out in the Municipality of Copenhagen, Denmark. The campaigns were distributed over 1 year. In each campaign, the personal exposure to benzene of 50 volunteers (non-smokers living in non-smoking families) living and working in Copenhagen was measured. Simultaneously, benzene was measured in their homes and in an urban network distributed over the municipality. The Radiello diffusive sampler was applied to sample 5 days averages of benzene and other hydrocarbons. Comparison of the results with those from a BTX-monitor showed excellent agreement. The exposure and the concentrations in homes and in the urban area were found to be close to log-normal distribution. The annual averages of the geometrical mean values were 5.22, 4.30 and 2.90 μg m -3 for personal exposure, home concentrations and urban concentrations, respectively. Two main parameters are controlling the general level of benzene in Copenhagen: firstly, the emission from traffic and secondly, dispersion due to wind speed. The general level of exposure to benzene and home concentrations of benzene were strongly correlated with the outdoor level of benzene, which indicated that traffic is an important source for indoor concentrations of benzene and for the exposure to benzene.

  8. Biomarkers of internal dose for the assessment of environmental exposure to benzene. (United States)

    Lovreglio, Piero; D'Errico, Maria Nicolà; Fustinoni, Silvia; Drago, Ignazio; Barbieri, Anna; Sabatini, Laura; Carrieri, Mariella; Apostoli, Pietro; Soleo, Leonardo


    The urinary excretion of t,t-muconic acid (t,t-MA), S-phenylmercapturic acid (SPMA) and urinary benzene and the influence of a smoking habit and of exposure to urban traffic on the urinary excretion of these biomarkers were investigated in 137 male adults from the general population. All subjects were not occupationally exposed to benzene and resident in two cities in Puglia (Southern-Italy). Environmental exposure to benzene was measured using passive personal samplers. The biomarkers t,t-MA, SPMA and urinary benzene were determined in urine samples collected from each subject at the end of the environmental sampling. The percentage of cases above the limit of detection was higher for SPMA and urinary benzene in smokers than in non-smokers, and for airborne benzene and urinary benzene in subjects exposed to urban traffic. Airborne benzene was correlated with the time spent in urban traffic during the environmental sampling. Among the biomarkers, urinary benzene was found to be correlated with airborne benzene only in non-smokers, and with the time spent in urban traffic, both in smokers and non-smokers considered together, and in non-smokers only. Finally, multiple regression analysis showed that the urinary excretion of all the biomarkers was dependent on the number of cigarettes smoked per day and, for urinary benzene, also on the time spent in urban traffic. In conclusion, urinary benzene seems to be a more valid biomarker than t,t-MA and SPMA to assess environmental exposure to extremely low concentrations of benzene. Cigarette smoking prevailed over traffic exhaust fumes in determining the internal dose of benzene.

  9. Modulation of the immune response to Listeria monocytogenes by benzene inhalation. (United States)

    Rosenthal, G J; Snyder, C A


    Benzene is a potent bone marrow toxicant. While all blood cell types are targets for benzene poisoning, lymphocytes are particularly sensitive. The immunotoxic consequences of benzene or its metabolites have been demonstrated in a number of in vitro studies; however, little data exist regarding the effects of benzene on host resistance to infectious agents. This investigation examined the effects of benzene on murine resistance to an infectious agent, Listeria monocytogenes. Four concentrations of benzene were employed, 10, 30, 100, and 300 ppm. To determine recovery from the effects of benzene, two exposure regimens were employed: 5 days prior to infection (preexposure), or 5 days prior to and 7 days during infection (continuous exposure). Appropriate air controls were maintained. Splenic bacterial counts and immune responsive cell populations were determined from mice killed at Days 1, 4, and 7 of infection. Preexposure to benzene produced increased bacterial numbers at Day 4 of the infection only at the highest benzene concentration (300 ppm). In contrast, continuous exposure produced increased bacterial numbers at Day 4 of infection at all but the lowest benzene concentration (10 ppm). Bacteria counts were not increased in any benzene-treated group at Day 1 or Day 7 of infection. The increased bacterial numbers at Day 4 suggest an effect on cell-mediated immune responses. Both T and B lymphocytes were particularly sensitive to benzene exhibiting reductions at all concentrations greater than or equal to 30 ppm for both exposure regimens. Esterase-positive cells, however, were relatively resistant to benzenes effects. The results point to a benzene-induced delay in the immune response to L. monocytogenes.

  10. Gene expression profile in bone marrow and hematopoietic stem cells in mice exposed to inhaled benzene

    Energy Technology Data Exchange (ETDEWEB)

    Faiola, Brenda; Fuller, Elizabeth S.; Wong, Victoria A.; Recio, Leslie


    Acute myeloid leukemia and chronic lymphocytic leukemia are associated with benzene exposure. In mice, benzene induces chromosomal breaks as a primary mode of genotoxicity in the bone marrow (BM). Benzene-induced DNA lesions can lead to changes in hematopoietic stem cells (HSC) that give rise to leukemic clones. To gain insight into the mechanism of benzene-induced leukemia, we investigated the DNA damage repair and response pathways in total bone marrow and bone marrow fractions enriched for HSC from male 129/SvJ mice exposed to benzene by inhalation. Mice exposed to 100 ppm benzene for 6 h per day, 5 days per week for 2 week showed significant hematotoxicity and genotoxicity compared to air-exposed control mice. Benzene exposure did not alter the level of apoptosis in BM or the percentage of HSC in BM. RNA isolated from total BM cells and the enriched HSC fractions from benzene-exposed and air-exposed mice was used for microarray analysis and quantitative real-time RT-PCR. Interestingly, mRNA levels of DNA repair genes representing distinct repair pathways were largely unaffected by benzene exposure, whereas altered mRNA expression of various apoptosis, cell cycle, and growth control genes was observed in samples from benzene-exposed mice. Differences in gene expression profiles were observed between total BM and HSC. Notably, p21 mRNA was highly induced in BM but was not altered in HSC following benzene exposure. The gene expression pattern suggests that HSC isolated immediately following a 2 weeks exposure to 100 ppm benzene were not actively proliferating. Understanding the toxicogenomic profile of the specific target cell population involved in the development of benzene-associated diseases may lead to a better understanding of the mechanism of benzene-induced leukemia and may identify important interindividual and tissue susceptibility factors.

  11. Molecular Dynamics Investigation of Benzene in Supercritical Water

    Institute of Scientific and Technical Information of China (English)


    Microscopic structure and diffusion properties of benzene in ambient water (298 K, 0.1 MPa) and super critical water (673-773 K, 25-35 MPa) are investigated by molecular dynamics simulation with site-site models. It is found that at the ambient condition, the water molecules surrounding a benzene molecule form a hydrogen bond network. The hydrogen bond interaction between supercritical water molecules decreases dramatically under supercritical conditions. The diffusion coefficients of both the solute molecule and solvent molecule at supercritical conditions increase by 30-180 times than those at the ambient condition. With the temperature approaching the critical temperature, the change of diffusion coefficient with pressure becomes pronounced.

  12. Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

    DEFF Research Database (Denmark)

    West, Keld; Bay, Lasse; Nielsen, Martin Meedom


    The electronic conductivity of the electroactive polymer polypyrrole-dodecyl benzene sulfonate (PPy-DBS) has been characterized as function of the redox level. The polymer was synthesized with different isomers of the dopant anions: the common mixed DBS tenside and three well-defined synthetic...... dodecyl isomers (with the benzene group at positions 1, 2 and 6). The conductivity was measured both by van der Pauw measurements on PPy-DBS in the oxidized, dry state as function of temperature, and by electrochemical impedance spectroscopy as function of potential in 0.1 M NaCl aqueous electrolyte...... carriers is at a minimum. The conductivity is further reduced because of the uptake of water at low potentials, creating electrolytic domains that separate the electronic domains and inhibit hopping. There is a pronounced hysteresis in the conductivity as a function of potential. However, the major part...

  13. Overtone spectroscopy of benzene derivatives using thermal lensing (United States)

    Vipin Prasad, J.; Rai, S. B.; Thakur, S. N.


    The vibrational overtones of CH stretching oscillators are reported as observed by conventional IR spectroscopy and dual-beam thermal lensing spectroscopy for benzene, fluorobenzene, chlorobenzene, bromobenzene and benzonitrile in the liquid phase at room temperature. The stretching frequency ω e, the anharmonicity constant ω eχ e and the change in CH bond length on substitution in benzene have been determined for all these molecules under the local-mode approximation. Effects of substitution on the change in CH stretching frequency have been discussed in terms of the electronegativity of the substituents as well as the inductive part of the Hammett σ. Variation of thermal lensing signal with chopping frequency and laser power has also been studied.

  14. Comparison of measurement methods for benzene and toluene (United States)

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

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

  15. Pure Benzene Will Be Serous Short of Supply

    Institute of Scientific and Technical Information of China (English)

    John Zheng


    @@ Benzene is one of the important ba-sic raw materials for petrochemicals.It can be used to synthesize a seriesof important chemical products suchas synthetic rubbers, synthetic resins,synthetic fibers, pharmaceuticals,pesticides, explosives and dyestuffs.It can also be used as a solvent forcoatings and rubbers and as a blend-ing agent to increase gasoline's oc-tane number in the refining sector.

  16. Adsorption isotherms for benzene on diatomites from China

    Institute of Scientific and Technical Information of China (English)

    YANG, Yu-Xianga; WU, Jie-Da; JIANG, Zhong-Liang; HUANG, Meng-Jian; CHEN, Rong-San; DAI, An-Bang


    In this paper, benzene adsorption isotherm and their hysteresis on two important local diatomites were determined at 25℃, ani their silicon hydroxyl group (SiOH) nunber was determined, their properties were reported, and the relationship between surface structure, surface SiOH number per nm2and adsorption isotherm with hysteresis was discussed. The specific surface was also calculated from the isotherms, and pore-size distribution was determined.

  17. Catalytic transformation of methyl benzenes over zeolite catalysts

    KAUST Repository

    Al-Khattaf, S.


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

  18. 2-Phenylimidazolium hemi(benzene-1,3-dicarboxylate monohydrate

    Directory of Open Access Journals (Sweden)

    Wen-Yu Zhang


    Full Text Available The asymmetric unit of the title compound, C9H9N2+·0.5C8H4O4−·H2O, contains one 2-phenylimidazolium cation, half a benzene-1,3-dicarboxylate anion and one water molecule. In the crystal, components are connected by N—H...O and O—H...O hydrogen-bonding interactions into a three-dimensional network.

  19. LED Irradiation of a Photocatalyst for Benzene, Toluene, Ethyl Benzene,and Xylene Decomposition%LED Irradiation of a Photocatalyst for Benzene,Toluene,Ethyl Benzene,and Xylene Decomposition

    Institute of Scientific and Technical Information of China (English)

    JO Wan-Kuen; KANG Hyun-Jung


    Studies on the use of gas phase applications of light emitting diodes (LEDs) in photocatalysis are scarce although their photocatalytic decomposition kinetics of environmental pollutants are likely different from those in aqueous solutions.The present study evaluated the use of chips of visible light LEDs to irradiate nitrogen doped titania (N-TiO2) prepared by hydrolysis to decompose gaseous benzene,toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene.Photocatalysts calcined at different temperatures were characterized by various analytical instruments.The degradation efficiency of benzene was close to zero for all conditions.For the other compounds,a conventional 8 W daylight lamp/N-TiO2 unit gave a higher photocatalytic degradation efficiency as compared with that of visible-LED/N-TiO2 units.However,the ratios of degradation efficiency to electric power consumption were higher for the photocatalytic units that used two types of visible-LED lamps (blue and white LEDs).The highest degradation efficiency was observed with the use of a calcination temperature of 350 ℃.The average degradation efficiencies for toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene were 35%,68%,94%,and 93%,respectively.The use of blue-and white-LEDs,high light intensity,and low initial concentrations gave high photocatalytic activities for the photocatalytic units using visible-LEDs.The morphological and optical properties of the photocatalysts were correlated to explain the dependence of photocatalytic activity on calcination temperature.The results suggest that visible-LEDs are energy efficient light source for photocatalytic gas phase applications,but the activity depends on the operational conditions.


    The stability of cysteinyl adducts of benzene oxide (BO) and mono-S-substituted cysteinyl adducts of 1,4-benzoquinone (1,4-BQ) was investigated in both hemoglobin (Hb) and albumin (Alb) following administration of a single oral dose of 400 mg [U-14C/13C6]benzene/kg body weight ...

  1. Alkylation reaction by propene of benzene on the high-temperature chlorination alumina catalyst; Koonensoshori arumina shokubaijo deno benzen no puropen nioru arukiruka hanno

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, Kazuhiro; Inui, Kanichiro; Honda, Kazuki; Shobu, Akinori


    Alkylation reaction by propene of benzene on alumina catalyst (AmLSA) chlorinated at 1073K was carried out using semibatch reactor (liquid phase catalytic reaction) and fixed bed flow reactor (vapor phase catalytic reaction) at atmospheric pressure 303K and 303-623K respectively. Products in liquid phase catalytic reaction were isopropyl benzene (IPB), diisopropyl benzene (di-IPB), triisopropyl benzene (tri-IPB), and the dissolution of the catalytic activity kind to the organic solvent was not observed. It was estimated, when propene was made to adsorb on Am LSA, because the generation of isopropylidene and 2 - propylene cation which coordinated in a strong Lewis acid point was observed, isopropyl reaction these cation benzene - complex. The generation of the high order substitute was promoted, when sodium was added to the catalyst, and the meta/para ratio of di-IPB increased. In vapor phase catalytic reaction, tetraisopropyl benzene (tetra-IPB) was also formed, and in the temperature of 473K or less, it was promoted further than the case in which the generation of tetra-IPB and di, tri was liquid phase catalytic reaction. IPB selectivity and selectivity of total replacement arthroplasty benzenes of consumed propene standard increased, when benzene/propene ratio in the raw material gas increased. In addition, at all reaction temperatures, the oligomerization of propene was generated, and the deactivation of the catalyst was caused. (translated by NEDO)

  2. Benzene exposure on a crude oil production vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kirkeleit, J; Riise, T.; Bratveit, M.; Moen, B.E. [University of Bergen (Norway). Dept. of Public Health and Primary Health Care


    Objectives: The aim was to describe the personal exposure to benzene on a typical crude oil production vessel and to identify factors influencing the exposure level. Methods: The study population included process operators, deck workers, mechanics and contractors on a production vessel in the Norwegian sector of the North Sea. The personal exposure to benzene during ordinary activity, during a short shutdown and during tank work was monitored using organic vapour passive dosimeter badges (3MTM3500). Information on the tasks performed on the day of sampling was recorded. Exposure was assessed by grouping the measurements according to job category, mode of operation and the tasks performed on the sampling day. Univariate analysis of variance was used to test the differences between the groups. Results: Forty-two workers participated in the exposure assessment, comprising a total of 139 measurements. The arithmetic and geometric mean of benzene exposure for all measurements was 0.43 and 0.02 p.p.m., respectively. Twenty-five measurements (18%) were below the limit of detection (0.001 p.p.m.), while ten samples (7%) exceeded the occupational exposure limit of 0.6 p.p.m. The geometric mean exposure was 0.004 p.p.m. (95% CI 0.003-0.006) during ordinary activity, 0.01 p.p.m. (95% CI 0.005-0.02) during shutdown and 0.28 p.p.m. (95% CI 0.16-0.49) during tank work. Workers performing annual cleaning and maintenance of tanks containing crude oil or residues of crude oil had higher levels of exposure than workers performing other tasks, including work near open hydrocarbon-transport systems (all P < 0.001). However, because of the mandatory use of respirators, the actual personal benzene exposure was lower. The job categories explained only 5% of the variance in exposure, whereas grouping by mode of operation explained 54% of the variance and grouping by task 68%. Conclusion: The results show that, although benzene exposure during ordinary and high activity seems to be low in

  3. Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens

    Directory of Open Access Journals (Sweden)

    Tian eZhang


    Full Text Available Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter metallireducens can anaerobically oxidize benzene to carbon dioxide with Fe(III as the sole electron acceptor and that phenol is an intermediate in benzene oxidation. In an attempt to identify enzymes that might be involved in the conversion of benzene to phenol, whole-genome gene transcript abundance was compared in cells metabolizing benzene and cells metabolizing phenol. Eleven genes had significantly higher transcript abundance in benzene-metabolizing cells. Five of these genes had annotations suggesting that they did not encode proteins that could be involved in benzene metabolism and were not further studied. Strains were constructed in which one of the remaining six genes was deleted. The strain in which the monocistronic gene Gmet 0232 was deleted metabolized phenol, but not benzene. Transcript abundance of the adjacent monocistronic gene, Gmet 0231, predicted to encode a zinc-containing oxidoreductase, was elevated in cells metabolizing benzene, although not at a statistically significant level. However, deleting Gmet 0231 also yielded a strain that could metabolize phenol, but not benzene. Although homologs of Gmet 0231 and Gmet 0232 are found in microorganisms not known to anaerobically metabolize benzene, the adjacent localization of these genes is unique to G. metallireducens. The discovery of genes that are specifically required for the metabolism of benzene, but not phenol in G. metallireducens is an important step in potentially identifying the mechanisms for anaerobic benzene activation.

  4. Monitoring low benzene exposure: comparative evaluation of urinary biomarkers, influence of cigarette smoking, and genetic polymorphisms. (United States)

    Fustinoni, Silvia; Consonni, Dario; Campo, Laura; Buratti, Marina; Colombi, Antonio; Pesatori, Angela C; Bonzini, Matteo; Bertazzi, Pier A; Foà, Vito; Garte, Seymour; Farmer, Peter B; Levy, Leonard S; Pala, Mauro; Valerio, Federico; Fontana, Vincenzo; Desideri, Arianna; Merlo, Domenico F


    Benzene is a human carcinogen and an ubiquitous environmental pollutant. Identification of specific and sensitive biological markers is critical for the definition of exposure to low benzene level and the evaluation of the health risk posed by this exposure. This investigation compared urinary trans,trans-muconic acid (t,t-MA), S-phenylmercapturic acid, and benzene (U-benzene) as biomarkers to assess benzene exposure and evaluated the influence of smoking and the genetic polymorphisms CYP2E1 (RsaI and DraI) and NADPH quinone oxidoreductase-1 on these indices. Gas station attendants, urban policemen, bus drivers, and two groups of controls were studied (415 subjects). Median benzene exposure was 61, 22, 21, 9 and 6 microg/m(3), respectively, with higher levels in workers than in controls. U-benzene, but not t,t-MA and S-phenylmercapturic acid, showed an exposure-related increase. All the biomarkers were strongly influenced by cigarette smoking, with values up to 8-fold higher in smokers compared with nonsmokers. Significant correlations of the biomarkers with each other and with urinary cotinine were found. A possible influence of genetic polymorphism of CYP2E1 (RsaI and/or DraI) on t,t-MA and U-benzene in subjects with a variant allele was found. Multiple linear regression analysis correlated the urinary markers with exposure, smoking status, and CYP2E1 (RsaI; R(2) up to 0.55 for U-benzene). In conclusion, in the range of investigated benzene levels (<478 micro/m(3) or <0.15 ppm), smoking may be regarded as the major source of benzene intake; among the study indices, U-benzene is the marker of choice for biomonitoring low-level occupational and environmental benzene exposure.

  5. Current understandings and perspectives on non-cancer health effects of benzene: A global concern

    Energy Technology Data Exchange (ETDEWEB)

    Bahadar, Haji [International Campus, Tehran University of Medical Sciences (Iran, Islamic Republic of); Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Mostafalou, Sara [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Abdollahi, Mohammad, E-mail: Mohammad.Abdollahi@UToronto.Ca [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of)


    Objective: Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored. Methodology: A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of “benzene toxic health effects”, “environmental volatile organic compounds”, “diabetes mellitus and environmental pollutants”, “breast cancer and environmental pollution”, “prevalence of lung cancer”, and “diabetes prevalence”. More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study. Results: Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory. Conclusion: Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up. - Highlights: • Benzene is a volatile organic compound and established blood carcinogen. • Exposure to benzene needs to be

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  7. A physiological model for simulation of benzene metabolism by rats and mice. (United States)

    Medinsky, M A; Sabourin, P J; Lucier, G; Birnbaum, L S; Henderson, R F


    Studies conducted by the National Toxicology Program on the chronic toxicity of benzene indicated that B6C3F1 mice are more sensitive to the toxic effects of benzene than are F344 rats. A physiological model was developed to describe the uptake and metabolism of benzene in rats and mice and to determine if the observed differences in toxic effects could be explained by differences in the pathways for metabolism of benzene or by differences in uptake of benzene. Major pathways for elimination of benzene included metabolism to hydroquinone glucuronide or hydroquinone sulfate, phenyl glucuronide or phenyl sulfate, muconic acid, and prephenyl mercapturic acid or phenyl mercapturic acid. Model simulations for total benzene metabolized and for profiles of benzene metabolites were conducted for oral or inhalation exposure and compared to data for urinary excretion of benzene metabolites after exposure of rats and mice to [14C]- or [3H]-benzene by inhalation or gavage. Results for total amount of benzene metabolized, expressed per kilogram body weight, indicated that for inhalation exposure concentrations up to 1000 ppm, mice metabolized at least two to three times as much benzene as did rats. Simulations of oral exposure to benzene resulted in more benzene metabolized per kilogram body weight by rats at oral exposures of greater than 50 mg/kg. Patterns of metabolites formed after either route of exposure were very different for F344/N rats and B6C3F1 mice. Rats primarily formed the detoxification metabolite, phenyl sulfate. Mice formed hydroquinone glucuronide and muconic acid in addition to phenyl sulfate. Hydroquinone and muconic acid are associated with pathways leading to the formation of the putative toxic metabolites of benzene. Metabolic rate parameters, Vmax and Km, were very different for hydroquinone conjugate and muconic acid formation compared to formation of phenyl conjugates and phenyl mercapturic acids. Putative toxication pathways could be characterized as

  8. Hematotoxicity and concentration-dependent conjugation of phenol in mice following inhalation exposure to benzene. (United States)

    Wells, M S; Nerland, D E


    Benzene is metabolized to one or more hematotoxic species. Saturation of benzene metabolism could limit the production of toxic species. Saturation of phase II enzymes involved in the conjugation of the phenolic metabolites of benzene also could affect the hematotoxicity of benzene. To investigate the latter possibility, we exposed male Swiss mice, via the inhalation route, to various concentrations of benzene for 6 h per day for 5 days. Following termination of the final exposure the mice were killed and the levels of phenylsulfate and phenylglucuronide in the blood determined. Spleen weights were recorded and the number of white blood cells counted. At low benzene exposure concentrations phenylsulfate is the major conjugated form of phenol in the blood. At high exposure concentrations, phenylglucuronide is the predominant species. The reductions in spleen weight and white blood cell numbers correlated with the concentration of phenylsulfate in the blood, but are most probably not causally related.

  9. Real-time diode laser measurements of vapor-phase benzene. (United States)

    Jeffers, J D; Roller, C B; Namjou, K; Evans, M A; McSpadden, L; Grego, J; McCann, P J


    An absorption spectrometer equipped with a IV-VI semiconductor tunable mid-IR diode laser was used to make sensitive measurements of benzene (C(6)H(6)) gas in the 5.1-microm spectral range. Wavelength modulation coupled with second-harmonic detection achieved accurate real-time quantification of benzene concentrations down to a minimum detection limit of 1 ppmv with an integration time of 4 s. A variety of calibrated benzene-sensing measurements were made, including the determination of the benzene concentrations in vehicle exhaust and headspace vapors from unleaded gasoline and other liquids. Kinetic phenomena, including the monitoring of benzene evaporation and absorption/desorption by granulated activated carbon were observed with the instrument. Measurements were performed that allowed experimental determination of the activation energy for desorption of benzene from activated carbon, which was found to be 198 meV/molecule (19.0 kJ/mol).

  10. The use of S-phenylmercapturic acid as a biomarker in molecular epidemiology studies of benzene. (United States)

    Farmer, Peter B; Kaur, Balvinder; Roach, Jonathan; Levy, Len; Consonni, Dario; Bertazzi, Pietro A; Pesatori, Angela; Fustinoni, Silvia; Buratti, Marina; Bonzini, Matteo; Colombi, Antonio; Popov, Todor; Cavallo, Domenico; Desideri, Arianna; Valerio, Federico; Pala, Mauro; Bolognesi, Claudia; Merlo, Franco


    S-Phenylmercapturic acid (S-PMA), is a urinary metabolite of benzene, thought to be derived from the condensation product of benzene oxide with glutathione. S-PMA may be determined by GC, HPLC (UV or fluorescence detection), GC-MS, LC-MS/MS or immunoassays. The limit of sensitivities of most of these techniques is 1 microg/l urine or below. It has been suggested that S-PMA may have value as a biomarker for low level human exposure to benzene, in view of the facts that urinary excretion of S-PMA has been found to be related to airborne benzene in occupationally exposed workers, and that only low background levels of S-PMA have been found in control subjects. We have evaluated the use of S-PMA as a biomarker, using a commercially available analytical service, in a multicentre European study of populations exposed to varying levels of benzene, in Italy (Milan, Genoa) and in Bulgaria (Sofia). These were filling station attendants, urban policemen, bus drivers, petrochemical workers and referents (a total of 623 subjects). S-PMA was measured at the end of the work shift by an immunoassay procedure. Urinary benzene (in Milan only) and the benzene metabolite trans,trans-muconic acid (t,t-MA) were measured before and after the work shift. Air-borne benzene was measured as a monitor of exposure. Urinary benzene was the most discriminatory biomarker and showed a relationship with airborne benzene at all levels of exposure studied (including groups exposed to <0.1 ppm benzene), whereas t,t-MA and S-PMA, as determined by immunoassay, were suitable only in the highest exposed workers (petrochemical industry, geometric mean 1765 microg/m3 (0.55 ppm) benzene). All three biomarkers were positively correlated with smoking as measured by urinary cotinine).

  11. Tissue distribution of DNA adducts and their persistence in blood of mice exposed to benzene.


    Li, G.; Wang, C.; Xin, W. (Weidong); Yin, S


    Chemicals combine with DNA, resulting in DNA damage, which could initiate carcinogenesis. To study whether benzene or benzene metabolites bind to DNA, DNA adducts in various tissues and their persistence in leukocytes were examined using the 32P-postlabeling assay. LACA mice were dosed ip with benzene at 500 mg/kg bw twice for 5 days. Two additional spots of DNA adducts are formed in bone marrow cells, liver cells, and peripheral blood compared with control mice. The relative adduct labeling ...

  12. Reduction of benzene metabolism and toxicity in mice that lack CYP2E1 expression. (United States)

    Valentine, J L; Lee, S S; Seaton, M J; Asgharian, B; Farris, G; Corton, J C; Gonzalez, F J; Medinsky, M A


    Transgenic CYP2E1 knockout mice (cyp2e1-/-) were used to investigate the involvement of CYP2E1 in the in vivo metabolism of benzene and in the development of benzene-induced toxicity. After benzene exposure, absence of CYP2E1 protein was confirmed by Western blot analysis of mouse liver samples. For the metabolism studies, male cyp2e1-/- and wild-type control mice were exposed to 200 ppm benzene, along with a radiolabeled tracer dose of [14C]benzene (1.0 Ci/mol) by nose-only inhalation for 6 hr. Total urinary radioactivity and all radiolabeled individual metabolites were reduced in urine of cyp2e1-/- mice compared to wild-type controls during the 48-hr period after benzene exposure. In addition, a significantly greater percentage of total urinary radioactivity could be accounted for as phenylsulfate conjugates in cyp2e1-/- mice compared to wild-type mice, indicating the importance of CYP2E1 in oxidation of phenol following benzene exposure in normal mice. For the toxicity studies, male cyp2e1-/-, wild-type, and B6C3F1 mice were exposed by whole-body inhalation to 0 ppm (control) or 200 ppm benzene, 6 hr/day for 5 days. On Day 5, blood, bone marrow, thymus, and spleen were removed for evaluation of micronuclei frequencies and tissue cellularities. No benzene-induced cytotoxicity or genotoxicity was observed in cyp2e1-/- mice. In contrast, benzene exposure resulted in severe genotoxicity and cytotoxicity in both wild-type and B6C3F1 mice. These studies conclusively demonstrate that CYP2E1 is the major determinant of in vivo benzene metabolism and benzene-induced myelotoxicity in mice.

  13. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, Francisco J., E-mail: [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)


    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.


    Institute of Scientific and Technical Information of China (English)

    张鸿源; 王兰金; 等


    The chromosomoe and chromatid type aberration can be induced by benzene and the dicentric and ring ones were not observed in vitro experiment but observed in vivo one.In vitro experiment a good linear reression can be given between benzene concentrations and total aberration cells while power regression for radiation dose.The chromosome aberrations induced by benzene combined with radiation in rabbit blood lymphocytes are higher than in bone marryow cells.

  15. Assessing benzene-induced toxicity on wild type Euglena gracilis Z and its mutant strain SMZ. (United States)

    Peng, Cheng; Arthur, Dionne M; Sichani, Homa Teimouri; Xia, Qing; Ng, Jack C


    Benzene is a representative member of volatile organic compounds and has been widely used as an industrial solvent. Groundwater contamination of benzene may pose risks to human health and ecosystems. Detection of benzene in the groundwater using chemical analysis is expensive and time consuming. In addition, biological responses to environmental exposures are uninformative using such analysis. Therefore, the aim of this study was to employ a microorganism, Euglena gracilis (E. gracilis) as a putative model to monitor the contamination of benzene in groundwater. To this end, we examined the wild type of E. gracilis Z and its mutant form, SMZ in their growth rate, morphology, chlorophyll content, formation of reactive oxygen species (ROS) and DNA damage in response to benzene exposure. The results showed that benzene inhibited cell growth in a dose response manner up to 48 h of exposure. SMZ showed a greater sensitivity compared to Z in response to benzene exposure. The difference was more evident at lower concentrations of benzene (0.005-5 μM) where growth inhibition occurred in SMZ but not in Z cells. We found that benzene induced morphological changes, formation of lipofuscin, and decreased chlorophyll content in Z strain in a dose response manner. No significant differences were found between the two strains in ROS formation and DNA damage by benzene at concentrations affecting cell growth. Based on these results, we conclude that E. gracilis cells were sensitive to benzene-induced toxicities for certain endpoints such as cell growth rate, morphological change, depletion of chlorophyll. Therefore, it is a potentially suitable model for monitoring the contamination of benzene and its effects in the groundwater.

  16. Benzene inhalation effects upon tetanus antitoxin. Responses and leukemogenesis in mice

    Energy Technology Data Exchange (ETDEWEB)

    Stoner, R D; Drew, R T; Bernstein, D M


    The effects of inhaled benzene on primary and secondary antibody responses and the incidence of leukemia in mice are reported. Young adult mice were given 5, 12, or 22 exposures to 400 ppM benzene for 6 hrs/day 5 days/week. After the exposure periods, the mice were immunized with absorbed tetanus toxoid (APTT) and/or fluid tetanus toxid (FTT). Exposure to benzene increasingly suppressed primary antibody responses to both antigens. Secondary antibody responses to FTT were nearly normal in animals given 10, 15, or 20 exposures to 400 ppM benzene. Other groups of mice were exposed to either 200 ppM or 50 ppM benzene. Primary antibody responses elicited with FTT and/or APTT were nearly normal in all mice exposed to 50 ppM benzene and in mice exposed to 200 ppM benzene for 5 days. However, 10 and 20 exposures to 200 ppM benzene inhibited antibody production. The effects of chronically inhaled 300 ppM benzene on the time of onset and incidence of leukemia in 400 7-month-old female HRS/J mice were also studied. Two genotypes were used; the (hr/hr) hairless mice are leukemia-prone, whereas the (hr/+) haired mice are more resistant to leukemia. The exposure continued for a period of 6 months. Lymphoid, myeloid, and mixed (lymphoid and myeloid) leukemias were observed. Ninety percent of the (hr/hr) mice exposed to benzene died from leukemia as compared with 91% for the (hr/hr) air control group. Eighty-five percent of the (hr/+) mice exposed to benzene died from leukemia as compared with 81% for the (hr/+) air control group. Exposures to 300 ppM benzene did not alter the time of onset or the incidence of leukemia commonly expected in HRS/J mice.

  17. Modeling of Pervaporation Separation Benzene from Dilute Aqueous Solutions Through Polydimethylsiloxane Membranes

    Institute of Scientific and Technical Information of China (English)

    彭福兵; 姜忠义


    A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.

  18. Combined analysis of job and task benzene air exposures among workers at four US refinery operations. (United States)

    Burns, Amanda; Shin, Jennifer Mi; Unice, Ken M; Gaffney, Shannon H; Kreider, Marisa L; Gelatt, Richard H; Panko, Julie M


    Workplace air samples analyzed for benzene at four US refineries from 1976 to 2007 were pooled into a single dataset to characterize similarities and differences between job titles, tasks and refineries, and to provide a robust dataset for exposure reconstruction. Approximately 12,000 non-task (>180 min) personal samples associated with 50 job titles and 4000 task (job titles and task codes across all four refineries, and (5) our analysis of variance (ANOVA) of the distribution of benzene air concentrations for select jobs/tasks across all four refineries. The jobs and tasks most frequently sampled included those with highest potential contact with refinery product streams containing benzene, which reflected the targeted sampling approach utilized by the facility industrial hygienists. Task and non-task data were analyzed to identify and account for significant differences within job-area, task-job, and task-area categories. This analysis demonstrated that in general, areas with benzene containing process streams were associated with greater benzene air concentrations compared to areas with process streams containing little to no benzene. For several job titles and tasks analyzed, there was a statistically significant decrease in benzene air concentration after 1990. This study provides a job and task-focused analysis of occupational exposure to benzene during refinery operations, and it should be useful for reconstructing refinery workers' exposures to benzene over the past 30 years.

  19. Tissue distribution of DNA adducts and their persistence in blood of mice exposed to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Guilan Li; Wang Chunguang; Songnian Yin [Institute of Occupational Medicine Chinese Academy of Preventive Medicine, Beijing (China); Weidong Xin [Medical College of Qingdao, Shandong Province (China)


    Chemicals combine with DNA, resulting in DNA damage, which could initiate carcinogenesis. To study whether benzene or benzene metabolites bind to DNA, DNA adducts in various tissues and their persistence in leukocytes were examined using the {sup 32}P-postlabeling assay. LACA mice were dosed in with benzene at 500 mg/kg bw twice daily for 5 days. Two additional spots of DNA adducts are formed in bone marrow cells, liver cells, and peripheral blood compared with control mice. The relative adduct labeling values are 10.39, 11.32, and 13.77 adducts; x 10{sup -8} nucleotides in these tissues, respectively. DNA adducts in blood leukocytes were observed at 1, 4, 7, 14, and 21 days after exposure to benzene, but adduct levels decreased as a function of time. Relative adduct labeling of {open_quotes}adduct B{close_quotes} declined linearly but mildly, while {open_quotes}adduct C{close_quotes} displayed a stepwise decrease. The relative adduct labeling values of both these adducts at day 14 were 50% of those at day 1 after the last treatment. Both adducts were still detectable at day 21 after benzene exposure. These studies demonstrate that benzene could induce DNA adducts; in bone marrow, liver, and white blood cells of mice dosed with benzene and that measurement of adducts in white blood cells may be useful as a biomarker to predict carcinogenic risk of benzene to workers exposed to benzene. 9 refs., 3 figs.

  20. Determination of benzene in different food matrices by distillation and isotope dilution HS-GC/MS

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros Vinci, Raquel [Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Canfyn, Michael [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium); De Meulenaer, Bruno [Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Schaetzen, Thibault de; Van Overmeire, Ilse; De Beer, Jacques [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium); Van Loco, Joris, E-mail: Joris.VanLoco@iph.fgov.BE [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium)


    Benzene is classified by the IARC as carcinogenic to humans. Several sources may contribute for the occurrence of benzene in foods, such as, environmental contamination and the reaction of benzoate salts with ascorbic acid (naturally present or added as food additives). Matrix effect on benzene recovery (e.g. in fatty foods) and artefactual benzene formation from benzoate during analysis in the presence of ascorbate are some of the challenges presented when determining benzene in a wide range of foodstuffs. Design of experiment (DOE) was used to determine the most important variables in benzene recovery from headspace GC/MS. Based on the results of the DOE, a versatile method for the extraction of benzene from all kind of food commodities was developed. The method which consisted of distillation and isotope dilution HS-GC/MS was in-house validated. Artefactual benzene was prevented by addition of a borate buffer solution (pH 11) under distillation conditions. The method presented in this study allows the use of a matrix-independent calibration with detection limits below the legal limit established by the European Council for benzene in drinking water (1 {mu}g L{sup -1}).

  1. Determination of benzene in different food matrices by distillation and isotope dilution HS-GC/MS. (United States)

    Vinci, Raquel Medeiros; Canfyn, Michael; De Meulenaer, Bruno; de Schaetzen, Thibault; Van Overmeire, Ilse; De Beer, Jacques; Van Loco, Joris


    Benzene is classified by the IARC as carcinogenic to humans. Several sources may contribute for the occurrence of benzene in foods, such as, environmental contamination and the reaction of benzoate salts with ascorbic acid (naturally present or added as food additives). Matrix effect on benzene recovery (e.g. in fatty foods) and artefactual benzene formation from benzoate during analysis in the presence of ascorbate are some of the challenges presented when determining benzene in a wide range of foodstuffs. Design of experiment (DOE) was used to determine the most important variables in benzene recovery from headspace GC/MS. Based on the results of the DOE, a versatile method for the extraction of benzene from all kind of food commodities was developed. The method which consisted of distillation and isotope dilution HS-GC/MS was in-house validated. Artefactual benzene was prevented by addition of a borate buffer solution (pH 11) under distillation conditions. The method presented in this study allows the use of a matrix-independent calibration with detection limits below the legal limit established by the European Council for benzene in drinking water (1 microg L(-1)).

  2. Pressure Dependence of Molar Volume near the Melting Point in Benzene

    Institute of Scientific and Technical Information of China (English)


    The pressure dependence of the molar volume was at constant temperatures close to the melting point in benzene. The molar volume of benzene was calculated using experimental data for the thermal expansivity for constant temperatures of 25℃, 28.5℃, 40℃, and 51℃ at various pressures for both the solid and liquid phases. The predictions are in good agreement with the observed volumes in both the solid and liquid phases of benzene. The predicted values of the molar volume for a constant temperature of 28.5℃ in the liquid phase of benzene agree well with experimental data in the literature.

  3. Electrostatic-field-enhanced photoexfoliation of bilayer benzene: A first-principles study (United States)

    Uchida, Kazuki; Silaeva, Elena P.; Watanabe, Kazuyuki


    Photoexfoliation of bilayer benzene in an external electrostatic (dc) field is studied using time-dependent density functional theory combined with molecular dynamics. We find that the dc-field-induced force on the upper benzene in addition to the repulsive interaction between the positively charged benzene molecules induced by the laser field leads to fast athermal exfoliation. Thus, we conclude that the dc field enhances the photoexfoliation due to dc-field emission in addition to laser-assisted photoemission. The athermal exfoliation process is shown to depend crucially on the charge state of benzene molecules rather than on the excitation energy supplied by the laser.

  4. Assisted bioremediation tests on three natural soils contaminated with benzene

    Directory of Open Access Journals (Sweden)

    Maria Manuela Carvalho


    Full Text Available Bioremediation is an attractive and useful method of remediation of soils contaminated with petroleum hydrocarbons because it is simple to maintain, applicable in large areas, is economic and enables an effective destruction of the contaminant. Usually, the autochthone microorganisms have no ability to degrade these compounds, and otherwise, the contaminated sites have inappropriate environmental conditions for microorganism’s development. These problems can be overcome by assisted bioremediation (bioaugmentation and/or biostimulation. In this study the assisted bioremediation capacity on the rehabilitation of three natural sub-soils (granite, limestone and schist contaminated with benzene was evaluated. Two different types of assisted bioremediation were used: without and with ventilation (bioventing. The bioaugmentation was held by inoculating the soil with a consortium of microorganisms collected from the protection area of crude oil storage tanks in a refinery. In unventilated trials, biostimulation was accomplished by the addition of a nutrient mineral media, while in bioventing oxygen was also added. The tests were carried out at controlled temperature of 25 ºC in stainless steel columns where the moist soil contaminated with benzene (200 mg per kg of soil occupied about 40% of the column’s volume. The processes were daily monitored in discontinued mode. Benzene concentration in the gas phase was quantified by gas chromatography (GC-FID, oxygen and carbon dioxide concentrations were monitored by respirometry. The results revealed that the three contaminated soils were remediated using both technologies, nevertheless, the bioventing showed faster rates. With this work it was proved that respirometric analysis is an appropriate instrument for monitoring the biological activity.

  5. trans-Dichloridobis(triphenylphosphane-κPpalladium(II benzene hemisolvate

    Directory of Open Access Journals (Sweden)

    Frank Meyer-Wegner


    Full Text Available The title complex, [PdCl2(C18H15P2]·0.5C6H6, has the PdII ion in a square-planar coordination mode (r.m.s. deviation for Pd, P and Cl atoms = 0.024 Å with the PPh3 and Cl ligands mutually trans. The benzene solvent molecule is located about a crystallographic inversion centre. The title complex is isostructural with trans-dichloridobis(triphenylphosphanepalladium(II 1,4-dichlorobenzene sesquisolvate [Kitano et al. (1983. Acta Cryst. C39, 1015–1017].

  6. Bis[diethyl(hydroxyammonium] benzene-1,4-dicarboxylate

    Directory of Open Access Journals (Sweden)

    De-Ming Xie


    Full Text Available In the centrosymmetric title compound, 2C4H12NO+·C8H4O42−, two N,N-diethyl(hydroxyammonium cations are linked to a benzene-1,4-dicarboxylate dianion by a combination of O—H...O and N—H...O hydrogen bonds, which can be described in graph-set terminology as R22(7. The crystal structure is further stabilized by C—H...O hydrogen bonds, leading to the fomation of a ribbon-like network.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  8. Male mice deficient in microsomal epoxide hydrolase are not susceptible to benzene-induced toxicity. (United States)

    Bauer, Alison K; Faiola, Brenda; Abernethy, Diane J; Marchan, Rosemarie; Pluta, Linda J; Wong, Victoria A; Gonzalez, Frank J; Butterworth, Byron E; Borghoff, Susan J; Everitt, Jeffrey I; Recio, Leslie


    Enzymes involved in benzene metabolism are likely genetic determinants of benzene-induced toxicity. Polymorphisms in human microsomal epoxide hydrolase (mEH) are associated with an increased risk of developing leukemia, specifically those associated with benzene. This study was designed to investigate the importance of mEH in benzene-induced toxicity. Male and female mEH-deficient (mEH-/-) mice and background mice (129/Sv) were exposed to inhaled benzene (0, 10, 50, or 100 ppm) 5 days/week, 6 h/day, for a two-week duration. Total white blood cell counts and bone marrow cell counts were used to assess hematotoxicity and myelotoxicity. Micronucleated peripheral blood cells were counted to assess genotoxicity, and the p21 mRNA level in bone marrow cells was used as a determinant of the p53-regulated DNA damage response. Male mEH-/- mice did not have any significant hematotoxicity or myelotoxicity at the highest benzene exposure compared to the male 129/Sv mice. Significant hematotoxicity or myelotoxicity did not occur in the female mEH-/- or 129/Sv mice. Male mEH-/- mice were also unresponsive to benzene-induced genotoxicity compared to a significant induction in the male 129/Sv mice. The female mEH-/- and 129/Sv mice were virtually unresponsive to benzene-induced genotoxicity. While p21 mRNA expression was highly induced in male 129/Sv mice after exposure to 100-ppm benzene, no significant alteration was observed in male mEH-/- mice. Likewise, p21 mRNA expression in female mEH-/- mice was not significantly induced upon benzene exposure whereas a significant induction was observed in female 129/Sv mice. Thus mEH appears to be critical in benzene-induced toxicity in male, but not female, mice.

  9. Impact of a new gasoline benzene regulation on ambient air pollutants in Anchorage, Alaska (United States)

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


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

  10. Alkylation of Benzene with Propylene Catalyzed by Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    Sun Xuewen; Zhao Suoqi


    The alkylation of benzene with propylene catalyzed by ionic liquids to obtain cumene was investigated. Propylene conversion and cumene selectivity under mild reaction conditions were improved greatly after the ionic liquid was modified with HCl. Under the conditions of 20 oC, 0.1MPa, 5 min of reaction time, and a molar ratio of benzene to propylene of 10:1, propylene conversion increased from 83.6% to 100%, and cumene selectivity increased from 90.86% to 98.47%. In addition, it was found that the reaction could be carried out in two different stages so as to obtain a better result. At the first stage, the key reaction was alkylation and a higher propylene conversion was obtained at a lower temperature;At the second stage, the key reaction was transalkylation and a higher temperature was used to improve cumene selectivity. The reaction temperature, pressure and the amount of catalyst used in this work were lower than those used in traditional alkylation processes.

  11. Catalytic oxidation of benzene using DBD corona discharges. (United States)

    Lu, B; Zhang, X; Yu, X; Feng, T; Yao, S


    Plasma oxidation of benzene (C(6)H(6)) in oxygen and nitrogen was investigated using a dielectric barrier discharge (DBD) reactor with or without MnO2 or TiO2 at atmospheric pressure and without external heating except plasma heating. An alternative current power supply was used to generate corona discharges for the plasma oxidation. The energy density was controlled under 200 J/L to keep an increase in gas temperature less than 167 K. C(6)H(6) was oxidized to carbon monoxide (CO) and dioxide (CO(2)). Typically, the energy efficiency at an energy density of 92J/L was about 0.052, 0.039, and 0.024 mol/kWh with MnO2, TiO2, and without MnO2 and TiO2, respectively. Benzene oxidation mechanism was mentioned. A comparison on energy efficiency as a function of initial concentration of hydrocarbons, inorganic sulphur compounds, and chloro (fluoro and bromo) carbons was given.

  12. Benzene oxide is a substrate for glutathione S-transferases. (United States)

    Zarth, Adam T; Murphy, Sharon E; Hecht, Stephen S


    Benzene is a known human carcinogen which must be activated to benzene oxide (BO) to exert its carcinogenic potential. BO can be detoxified in vivo by reaction with glutathione and excretion in the urine as S-phenylmercapturic acid. This process may be catalyzed by glutathione S-transferases (GSTs), but kinetic data for this reaction have not been published. Therefore, we incubated GSTA1, GSTT1, GSTM1, and GSTP1 with glutathione and BO and quantified the formation of S-phenylglutathione. Kinetic parameters were determined for GSTT1 and GSTP1. At 37 °C, the putative Km and Vmax values for GSTT1 were 420 μM and 450 fmol/s, respectively, while those for GSTP1 were 3600 μM and 3100 fmol/s. GSTA1 and GSTM1 did not exhibit sufficient activity for determination of kinetic parameters. We conclude that GSTT1 is a critical enzyme in the detoxification of BO and that GSTP1 may also play an important role, while GSTA1 and GSTM1 seem to be less important.

  13. Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry (United States)

    Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan


    Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

  14. Separation of Benzene and Cyclohexane by Batch Extractive Distillation

    Institute of Scientific and Technical Information of China (English)

    XU Jiao; ZHANG Weijiang; GUI Xia


    Azeotropic liquid mixture cannot be separated by conventional distillation. But extractive distillation or combination of the two can be valid for them. An experiment to separate benzene and cyclohexane by batch extractive distillation was carried out with N, N-dimethylformide (DMF), dimethyl sulfoxide (DMSO) and their mixture as extractive solvent. The effect of the operation parameterssuch as solvent flow rate and reflux ratio on the separation was studied under the same operating conditions. The results show that the separation effect was improved with the increase of solvent flow rate and the reflux ratio; all the three extractive solvents can separate benzene and cyclohexane, with DMF being the most efficient one, the mixture the second, and DMSO the least. In the experiment the best operation conditions are with DMF as extractive solvent, the solvent flow rate being 12.33 mL/min, and the reflux ratio being 6. As a result, we can get cyclohexane from the top of tower with the average product content being 86.98%, and its recovering ratio being 83.10%.

  15. Chemical accuracy from quantum Monte Carlo for the benzene dimer

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Sam, E-mail: [Department of Earth Science and Thomas Young Centre, University College London, London WC1E 6BT (United Kingdom); Cohen, R. E. [London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom and Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015 (United States)


    We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of −2.3(4) and −2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is −2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods.

  16. Analyzing Benzene and Cyclohexane Emulsion Droplet Collisions on Ultramicroelectrodes. (United States)

    Li, Yan; Deng, Haiqiang; Dick, Jeffrey E; Bard, Allen J


    We report the collisions of single emulsion oil droplets with extremely low dielectric constants (e.g., benzene, ε of 2.27, or cyclohexane, ε of 2.02) as studied via emulsion droplet reactor (EDR) on an ultramicroelectrode (UME). By applying appropriate potentials to the UME, we observed the electrochemical effects of single-collision signals from the bulk electrolysis of single emulsion droplets. Different hydrophobic redox species (ferrocene, decamethyl-ferrocene, or metalloporphyrin) were trapped in a mixed benzene (or cyclohexane) oil-in-water emulsion using an ionic liquid as the supporting electrolyte and emulsifier. The emulsions were prepared using ultrasonic processing. Spike-like responses were observed in each i-t response due to the complete electrolysis of all of the above-mentioned redox species within the droplet. On the basis of these single-particle collision results, the collision frequency, size distribution, i-t decay behavior of the emulsion droplets, and possible mechanisms are analyzed and discussed. This work demonstrated that bulk electrolysis can be achieved in a few seconds in these attoliter reactors, suggesting many applications, such as analysis and electrosynthesis in low dielectric constant solvents, which have a much broader potential window.

  17. Variability of benzene exposure among filling station attendants; Variabilita` dell`esposizione a benzene tra gli addetti all`erogazione di carburanti

    Energy Technology Data Exchange (ETDEWEB)

    Carere, A.; Iacovella, N.; Turrio Baldassarri, L. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Tossicologia Comparata ed Ecotossicologia; Fuselli, S.; Iavarone, I.; Lagorio, S.; Proietto, A.R. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Igiene Ambientale


    A monitoring survey of filling station attendants aimed at identifying sources of variability of exposure to benzene and other aromatics was carried out. Concurrent samples of the worker`s breathing zone air, atmospheric air in the service station proximity, and gasoline were collected, along with information about daily workloads and other exposure-related factors. Benzene personal exposure was characterised by a small between-worker variability and a predominant within-worker variance component. Such elevated day-to-day variability yields to imprecise estimates of mean personal exposure. Almost 70% of the overall personal exposure variance was explained by a model including daily benzene from dispensed fuel, presence of a shelter over the refueling area, amount of fuel supplied to the station if a delivery occurred, and background atmospheric benzene concentration.

  18. MiR-133a regarded as a potential biomarker for benzene toxicity through targeting Caspase-9 to inhibit apoptosis induced by benzene metabolite (1,4-Benzoquinone). (United States)

    Chen, Yujiao; Sun, Pengling; Bai, Wenlin; Gao, Ai


    Benzene is an environmental and industrial chemical which is widely utilized in various applications. Our previous study showed that miR-133a expression was down-regulated in chronic benzene poisoning workers, but the mechanism of miR-133a in benzene-induced hematotoxicity remains unclear. In this population-based study, benzene-exposed group recruited workers whose concentration of air benzene was 3.50±1.60mg/m(3), and control workers who were exposed to 0.06±0.01mg/m(3) air benzene. By comparison, Caspase-9 and Caspase-3 was up-regulated while miR-133a expression decreased in benzene-exposed workers. Pearson correlation analysis showed that miR-133a was reversely correlated with pro-apoptotic gene Caspase-9 in population-based study. Moreover, multiple linear regressions indicated that miR-133a was positively associated with blood cells count. To explore the underlying mechanism of miR-133a in benzene-induced hematotoxicity, AO/EB staining and TEM ultrastructural analysis were conducted to verify the activation of apoptosis in Human Leukemic U937 Cells induced by benzene metabolites (1,4-Benzoquinone, 1,4-BQ), while the mechanism of miR-133a in 1,4-BQ-induced apoptosis was performed using lentivirus vectors transfection. The results demonstrated that 1,4-BQ evidently induced mitochondria-mediated apoptosis and increased pro-apoptotic genes (Caspase-9 and Caspase-3) expression in a dose-dependent manner. The mechanistic study showed 1,4-BQ decreased miR-133a expression and miR-133a over-expression attenuated 1, 4-BQ-caused upregulation of Caspase-9, Caspase-3 and apoptosis. In conclusion, our research suggested that benzene induced hematotoxicity by decreasing miR-133a and caspase-dependent apoptosis which might contribute to the underlying mechanism of miR-133a in benzene-induced hematotoxicity.

  19. Hydrogenation of Benzene over Mo2C/Al2O3 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing; Wu Weicheng


    The process of benzene hydrogenation over Mo2C catalyst has been studied.Mo2C was the active phase in benzene hydrogenation.The major problem with the metal carbides was their poor stability due to deactivation by carbon deposition.

  20. Genome-wide functional profiling reveals genes required for tolerance to benzene metabolites in yeast.

    Directory of Open Access Journals (Sweden)

    Matthew North

    Full Text Available Benzene is a ubiquitous environmental contaminant and is widely used in industry. Exposure to benzene causes a number of serious health problems, including blood disorders and leukemia. Benzene undergoes complex metabolism in humans, making mechanistic determination of benzene toxicity difficult. We used a functional genomics approach to identify the genes that modulate the cellular toxicity of three of the phenolic metabolites of benzene, hydroquinone (HQ, catechol (CAT and 1,2,4-benzenetriol (BT, in the model eukaryote Saccharomyces cerevisiae. Benzene metabolites generate oxidative and cytoskeletal stress, and tolerance requires correct regulation of iron homeostasis and the vacuolar ATPase. We have identified a conserved bZIP transcription factor, Yap3p, as important for a HQ-specific response pathway, as well as two genes that encode putative NAD(PH:quinone oxidoreductases, PST2 and YCP4. Many of the yeast genes identified have human orthologs that may modulate human benzene toxicity in a similar manner and could play a role in benzene exposure-related disease.

  1. Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media. (United States)

    Sutter, Benjamin; Ravera, Christel; Hussard, Caroline; Langlois, Eddy


    Benzene is frequently used to extract collected bitumen fumes from personal sampler substrates. However, this solvent is particularly dangerous because of its carcinogenicity (group 1 of the International Agency for Research on Cancer classification). Therefore, to prevent the exposure of laboratory technicians to benzene during the fume extraction step from samplers, a compromise had to be found to identify a less toxic solvent with the same extraction capacity. To compare the extraction capacities of selected solvents, bitumen fumes were generated in the laboratory from three different batches of road surfacing bitumen collected on dedicated bitumen fume samplers. The samplers were then extracted by benzene and the solvents tested. Of 11 selected solvents less toxic than benzene and used in studies on bitumen and bitumen fume analyses, n-hexane and n-heptane were identified as alternatives to benzene. In particular, the results demonstrated that n-heptane was the best candidate solvent for benzene replacement, due to its extraction efficiency comparable to benzene for the three bitumen fumes tested and its low toxicity, which is highly compatible with benzene replacement.

  2. Differential susceptibility of rats and guinea pigs to the ototoxic effects of ethyl benzene

    NARCIS (Netherlands)

    Cappaert, NLM; Klis, SFL; Muijser, H; Kulig, BM; Ravensberg, LC; Smoorenburg, GF


    The present study was designed to compare the ototoxic effects of volatile ethyl benzene in guinea pigs and rats. Rats showed deteriorated auditory thresholds in the mid-frequency range, based on electrocochleography, after 550-ppm ethyl benzene (8 h/day, 5 days). Outer hair cell (OHC) loss was foun

  3. Multiphoton Ionization of Mixed Benzene-Water-Metanol Clusters. Competitive Microscopic Solvation (United States)

    Börnsen, K. O.; Selzle, H. L.; Schlag, E. W.


    Clusters of benzene with polar molecules are observed from a supersonic jet expansion of a ternary mixture of benzene, water and methanol seeded in Helium. It is found that complex formation with methanol is strongly enhanced when a single water molecule is preadsorbed.

  4. Assessment of human exposure to benzene through foods from the Belgian market. (United States)

    Medeiros Vinci, Raquel; Jacxsens, Liesbeth; Van Loco, Joris; Matsiko, Eric; Lachat, Carl; de Schaetzen, Thibault; Canfyn, Michael; Van Overmeire, Ilse; Kolsteren, Patrick; De Meulenaer, Bruno


    Benzene is a volatile organic compound known to be carcinogenic to humans (Group 1) and may be present in food. In the present study, 455 food samples from the Belgian market were analyzed for benzene contents and some possible sources of its occurrence in the foodstuffs were evaluated. Benzene was found above the level of detection in 58% of analyzed samples with the highest contents found in processed foods such as smoked and canned fish, and foods which contained these as ingredients (up to 76.21 μg kg(-1)). Unprocessed foods such as raw meat, fish, and eggs contained much lower concentrations of benzene. Using the benzene concentrations in food, a quantitative dietary exposure assessment of benzene intake was conducted on a national representative sample of the Belgian population over 15 years of age. The mean benzene intake for all foods was 0.020 μg kg bw d(-1) according to a probabilistic analysis. These values are below the minimum risk level for oral chronic exposure to benzene (0.5 μg kg bw d(-1)).

  5. Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dipty [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India); Fulekar, M.H., E-mail: [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)


    Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

  6. Effects of benzene inhalation on lymphocyte subpopulations and immune response in mice. (United States)

    Aoyama, K


    To clarify the immunotoxicity of benzene, the effects of benzene inhalation on T and B lymphocytes and immune responses in mice were examined. BALB/c male mice were exposed to 50 or 200 ppm benzene vapor, 6 hr/day for 7 or 14 consecutive days. T and B lymphocytes, in blood and spleen, were detected by the cytotoxicity assay with anti-Thy-1.2 monoclonal antibody and the membrane immunofluorescence test with anti-immunoglobulin antibody, respectively. Humoral immune response to sheep red blood cells was determined by the hemolytic plaque-forming cell assay. Cell-mediated immune response was measured by contact sensitivity (CS) to picryl chloride. The activity of suppressor cells was evaluated in spleen by the suppressive effect on passive transfer of CS. The ratio and absolute number of T and B lymphocytes in blood and spleen were depressed after a 7-day exposure at 50 ppm benzene. The depression of B lymphocytes was dose dependent and more intense than that of T lymphocytes. The ability to form antibodies was suppressed by benzene at all exposure levels, but the CS response was resistant to benzene inhalation and rather enhanced at 200 ppm exposure for 14 days. The activity of suppressor cells could not be detected at this dose level. These data show that benzene inhalation effects on humoral and cell-mediated immune responses are a result of the selective toxicity of benzene to B lymphocytes and suppressor T cells.

  7. Formation of a new benzene-ethane co-crystalline structure under cryogenic conditions. (United States)

    Vu, Tuan Hoang; Cable, Morgan L; Choukroun, Mathieu; Hodyss, Robert; Beauchamp, Patricia


    We report the first experimental finding of a solid molecular complex between benzene and ethane, two small apolar hydrocarbons, at atmospheric pressure and cryogenic temperatures. Considerable amounts of ethane are found to be incorporated inside the benzene lattice upon the addition of liquid ethane onto solid benzene at 90-150 K, resulting in formation of a distinctive co-crystalline structure that can be detected via micro-Raman spectroscopy. Two new features characteristic of these co-crystals are observed in the Raman spectra at 2873 and 1455 cm(-1), which are red-shifted by 12 cm(-1) from the υ1 (a1g) and υ11 (eg) stretching modes of liquid ethane, respectively. Analysis of benzene and ethane vibrational bands combined with quantum mechanical modeling of isolated molecular dimers reveal an interaction between the aromatic ring of benzene and the hydrogen atoms of ethane in a C-H···π fashion. The most favored configuration for the benzene-ethane dimer is the monodentate-contact structure, with a calculated interaction energy of 9.33 kJ/mol and an equilibrium bonding distance of 2.66 Å. These parameters are comparable to those for a T-shaped co-crystalline complex between benzene and acetylene that has been previously reported in the literature. These results are relevant for understanding the hydrocarbon cycle of Titan, where benzene and similar organics may act as potential hydrocarbon reservoirs due to this incorporation mechanism.


    Institute of Scientific and Technical Information of China (English)


    @@Benzene is an established cause of leukemia at high doses, but the risk it poses at exposures of ≤1ppm in air is diffcult to quantify. Molecular biomarkers may improve the accuracy of this risk assessment. We have therefore attempted to develop and validate biomarkers of exposure, early effect and susceptibility to benzene. We have shown


    Little is known about the formation and disposition of benzene oxide (BO), the initial metabolite arising from oxidation of benzene by cytochrome P450. In this study, reactions of BO with hemoglobin (Hb) and albumin (Alb) were investigated in blood from B6C3F1 mice, F344 rats, ...

  10. 优化苯塔流程减少石油苯损失%To Optimize the Benzene Tower Process and Reduce Oil Benzene Loss

    Institute of Scientific and Technical Information of China (English)

    聂玉萍; 佟文媛


    歧化装置包括歧化和烷基化转移部分及苯-甲苯分馏部分,通过探讨歧化装置各部分操作及石油苯产量状况,围绕如何减少石油苯损失,提高石油苯产量展开讨论,最终得出结论并制定对策以期能够减少石油苯损失,提高石油苯产量,从而提高经济效益。%Disproportionation unit includes disproportionation and alkylation transfer part and the benzene-toluene fractionation part, this paper discussed how to reduce oil benzene loss and improve oil benzene production through the discussion of the operation of each part of disproportionation unit and the status of oil benzene production, and eventually reached a conclusion and developed countermeasures to reduce oil benzene loss and improve oil benzene production, thus enhancing economic efficiency.

  11. Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge. (United States)

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


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

  12. Hydrogen Storage in Benzene Moiety Decorated Single-Walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing-Yun; LIANG Qi-Min; SONG Chen; XIA Yue-Yuan; ZHAO Ming-wen; LIU Xiang-Dong; ZHANG Hong-Yu


    The hydrogen storage capacity of(5,5)single-walled carbon nanotubes(SWNTs)decorated chemically with benzene moieties is studied by using molecular dynamics simulations(MDSs)and density functional theory(DFT) calculations.It is found that benzene molecules colliding on (5,5) SWNTs at incident energy of 50 eV form very stable configurations of benzene moiety adsorption on the wall of SWNTs.The MDSs indicate that when the benzene moiety decorated(5,5)SWNTs and a pristine(5,5)SWNT are put in a box in which hydrogen molecules are filled to a pressure of~26 atm,the hydrogen storage capacity of the benzene moiety decorated(5,5)SWNT is about 4.7wt.% and that of the pristine (5,5) SwNT is nearly 3.9 wt.%.

  13. The influence of ethanol on the stem cell toxicity of benzene in mice. (United States)

    Seidel, H J; Bader, R; Weber, L; Barthel, E


    BDF1 mice were exposed to 100, 300, and 900 ppm benzene vapor, and the numbers of hematopoietic progenitor cells, early and late erythroid progenitors (BFU-E and CFU-E) and granuloid progenitors (CFU-C), were determined with and without additional exposure to ethanol (5, 10, 15 vol%) in the drinking water. The duration of benzene inhalation was up to 4 weeks, 6 hr per day, 5 days per week. It was shown that the number of CFU-E per femur was depressed in a dose-dependent manner by benzene alone and also by ethanol combined with a given benzene concentration. CFU-E showed rapid regeneration after the end of the exposure, but not BFU-E and CFU-C. Prolongation of the ethanol exposure after withdrawal of benzene had only a marginal effect on progenitor cell regeneration.

  14. Marine environmental protection: An application of the nanometer photo catalyst method on decomposition of benzene. (United States)

    Lin, Mu-Chien; Kao, Jui-Chung


    Bioremediation is currently extensively employed in the elimination of coastal oil pollution, but it is not very effective as the process takes several months to degrade oil. Among the components of oil, benzene degradation is difficult due to its stable characteristics. This paper describes an experimental study on the decomposition of benzene by titanium dioxide (TiO2) nanometer photocatalysis. The photocatalyst is illuminated with 360-nm ultraviolet light for generation of peroxide ions. This results in complete decomposition of benzene, thus yielding CO2 and H2O. In this study, a nonwoven fabric is coated with the photocatalyst and benzene. Using the Double-Shot Py-GC system on the residual component, complete decomposition of the benzene was verified by 4h of exposure to ultraviolet light. The method proposed in this study can be directly applied to elimination of marine oil pollution. Further studies will be conducted on coastal oil pollution in situ.

  15. Sorption of phenanthrene and benzene on differently structural kerogen: important role of micropore-filling. (United States)

    Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong


    Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23-46% and 36-65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling.

  16. Effects of hydrogen and acetate on benzene mineralisation under sulphate-reducing conditions. (United States)

    Rakoczy, Jana; Schleinitz, Kathleen M; Müller, Nicolai; Richnow, Hans H; Vogt, Carsten


    Syntrophic mineralisation of benzene, as recently proposed for a sulphate-reducing enrichment culture, was tested in product inhibition experiments with acetate and hydrogen, both putative intermediates of anaerobic benzene fermentation. Using [(13)C(6)]-benzene enabled tracking the inhibition of benzene mineralisation sensitively by analysis of (13)CO(2). In noninhibited cultures, hydrogen was detected at partial pressures of 2.4 × 10(-6) ± 1.5 × 10(-6) atm. Acetate was detected at concentrations of 17 ± 2 μM. Spiking with 0.1 atm hydrogen produced a transient inhibitory effect on (13)CO(2) formation. In cultures spiked with higher amounts of hydrogen, benzene mineralisation did not restart after hydrogen consumption, possibly due to the toxic effects of the sulphide produced. An inhibitory effect was also observed when acetate was added to the cultures (0.3, 3.5 and 30 mM). Benzene mineralisation resumed after acetate was degraded to concentrations found in noninhibited cultures, indicating that acetate is another key intermediate in anaerobic benzene mineralisation. Although benzene mineralisation by a single sulphate reducer cannot be ruled out, our results strongly point to an involvement of syntrophic interactions in the process. Thermodynamic calculations revealed that, under in situ conditions, benzene fermentation to hydrogen and acetate yielded a free energy change of ΔG'=-83.1 ± 5.6 kJ mol(-1). Benzene mineralisation ceased when ΔG' values declined below -61.3 ± 5.3 kJ mol(-1) in the presence of acetate, indicating that ATP-consuming reactions are involved in the pathway.

  17. Electronic noses for monitoring benzene occupational exposure in biological samples of Egyptian workers

    Directory of Open Access Journals (Sweden)

    Ehab I. Mohamed


    Full Text Available Objectives: Benzene is commonly emitted in several industries, leading to widespread environmental and occupational exposure hazards. While less toxic solvents have been substituted for benzene, it is still a component of petroleum products and is a trace impurity in industrial products resulting in continued higher occupational exposures in industrial settings in developing countries. Materials and Methods: We investigated the potential use of an electronic nose (e-nose to monitor the headspace volatiles in biological samples from benzene-exposed Egyptian workers and non-exposed controls. The study population comprised 150 non-smoking male workers exposed to benzene and an equal number of matching non-exposed controls. We determined biomarkers of benzene used to estimate exposure and risk including: benzene in exhaled air and blood; and its urinary metabolites such as phenol and muconic acid using gas chromatography technique and a portable e-nose. Results: The average benzene concentration measured in the ambient air of the workplace of all studied industrial settings in Alexandria, Egypt; was 97.56±88.12 μg/m3 (range: 4.69–260.86 μg/m3. Levels of phenol and muconic acid were signifi cantly (p < 0.001 higher in both blood and urine of benzene-exposed workers as compared to non-exposed controls. Conclusions: The e-nose technology has successfully classifi ed and distinguished benzene-exposed workers from non-exposed controls for all measured samples of blood, urine and the exhaled air with a very high degree of precision. Thus, it will be a very useful tool for the low-cost mass screening and early detection of health hazards associated with the exposure to benzene in the industry.

  18. Effect Of Polar Component(1-Propanol On The RelativeVolatility Of The Binary System N-Hexane - Benzene

    Directory of Open Access Journals (Sweden)

    Khalid Farhod Chasib Al-Jiboury


    Full Text Available Vapor-liquid equilibrium data are presented for the binary systems n-hexane - 1-propanol, benzene - 1-propanol and n-hexane – benzene at 760 mm of mercury pressure. In addition ternary data are presented at selected compositions with respect to the 1-propanol in the 1-propanol, benzene, n-hexane system at 760 mmHg. The results indicate the relative volatility of n-hexane relative to benzene increases appreciably with addition of 1-propanol

  19. In situ FTIR Investigation of Magnetic Field Effect on Heterogeneous Photocatalytic Degradation of Benzene over Pt/TiO2

    Institute of Scientific and Technical Information of China (English)


    In situ FTIR spectroscopy was utlized to investigate the magnetic field effect on the heterogeneous photocatalytic degradation of benzene over platinized titania (Pt/TiO2). The results revealed that the employment of magnetic field may not change the mechanism of photocatalytic degradation of benzene, however, it greatly facilitate the conversion of benzene to phenol and quinone, as well as the transformation from phenol to quinone, resulting in opening the benzene ring easily and promoting the production of CO2.

  20. Nonthermal plasma assisted photocatalytic oxidation of dilute benzene

    Indian Academy of Sciences (India)

    J Karuppiah; E Linga Reddy; L Sivachandiran; R Karvembu; Ch Subrahmanyam


    Oxidative decomposition of low concentrations (50-1000 ppm) of diluted benzene in air was carried out in a nonthermal plasma (NTP) dielectric barrier discharge (DBD) reactor with the inner electrode made up of stainless steel fibres (SMF) modified with transition metal oxides in such a way to integrate the catalyst in discharge zone. Typical results indicate the better performance of MnO and TiO2/MnO modified systems, which may be attributed to the in situ decomposition of ozone on the surface of MnO that may lead to the formation of atomic oxygen; whereas ultraviolet light induced photocatalytic oxidation may be taking place with TiO2 modified systems. Water vapour improved the selectivity to total oxidation.

  1. Assessment of population exposure to air pollution by benzene. (United States)

    Tchepel, Oxana; Penedo, Ana; Gomes, Madalena


    Biomonitoring is one of the methods that allow to identify population groups that have significantly higher exposures to a particular chemical than the general population. However, use of biomonitoring is particularly useful when applied in combination with other methods of pollution exposure assessment. The current study is focused on the developing of the modelling approach to estimate population exposure to benzene through inhalation. The model is based on a microenvironment approach and is adapted to be applied in urban areas where the pattern of exposure is complex. The results provided by the model may be used in combination with human biomonitoring in order to select who and where should monitoring be done, as well as for interpretation and extrapolation of biomonitoring results.

  2. Localized helium excitations in 4He_N-benzene clusters

    CERN Document Server

    Huang, P; Huang, Patrick


    We compute ground and excited state properties of small helium clusters 4He_N containing a single benzene impurity molecule. Ground-state structures and energies are obtained for N=1,2,3,14 from importance-sampled, rigid-body diffusion Monte Carlo (DMC). Excited state energies due to helium vibrational motion near the molecule surface are evaluated using the projection operator, imaginary time spectral evolution (POITSE) method. We find excitation energies of up to ~23 K above the ground state. These states all possess vibrational character of helium atoms in a highly anisotropic potential due to the aromatic molecule, and can be categorized in terms of localized and collective vibrational modes. These results appear to provide precursors for a transition from localized to collective helium excitations at molecular nanosubstrates of increasing size. We discuss the implications of these results for analysis of anomalous spectral features in recent spectroscopic studies of large aromatic molecules in helium clu...

  3. Benzene ring chains with lithium adsorption: Vibrations and their implications

    CERN Document Server

    Stegmann, Thomas; Seligman, Thomas H


    Lithium adsorption on aromatic molecules and polyacenes have been found to produce strong distortions associated to spontaneous symmetry breaking and lesser ones in more general cases. For polyphenyls we find similar, but more varied behaviour; an important feature is the fact that adsorption largely suppresses the torsion present in naked polyphenyl. The spectra of the vibrational modes distinguish the different structures of skeletons and adsorbates. In the more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essential followed by the adsorbate. Based on this we propose the possible use of such a chain of adsorbates on a chain of benzene rings as a quantum register with the lowest vibrations transmitting qubits for control gates. To strengthen this view and to show the effect of heavier alkalines we also present the very symmetric adsorption of ten rubidium atoms on pentaphenyl.

  4. Separation of Scintillation and Cherenkov Lights in Linear Alkyl Benzene

    CERN Document Server

    Li, Mohan; Yeh, Minfang; Wang, Zhe; Chen, Shaomin


    To separate scintillation and Cherenkov lights in water-based liquid scintillator detectors is a desired feature for future neutrino and proton decay researches. Linear alkyl benzene (LAB) is one important ingredient of a water-based liquid scintillator being developed. In this paper we observed a good separation of scintillation and Cherenkov lights in an LAB sample. The rising and decay times of the scintillation light of the LAB were measured to be $(7.7\\pm3.0)\\ \\rm{ns}$ and $(36.6\\pm2.4)\\ \\rm{ns}$, respectively, while the full width [-3$\\sigma$, 3$\\sigma$] of the Cherenkov light was 12 ns dominated by the time resolution of our photomultiplier tubes. The light yield of the scintillation was measured to be $(1.01\\pm0.12)\\times10^3\\ \\rm{photons}/\\rm{MeV}$.

  5. Adsorption of benzene, cyclohexane and hexane on ordered mesoporous carbon. (United States)

    Wang, Gang; Dou, Baojuan; Zhang, Zhongshen; Wang, Junhui; Liu, Haier; Hao, Zhengping


    Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal.

  6. 3-[(E-(4-Ethylphenyliminomethyl]benzene-1,2-diol

    Directory of Open Access Journals (Sweden)

    Zeynep Keleşoğlu


    Full Text Available The title compound, C15H15NO2, adopts the enol–imine tautomeric form. The dihedral angle between the two benzene rings is 48.1 (1°. Intramolecular O—H...N and O—H...O hydrogen bonds generate S(6 and S(5 ring motifs, respectively. In the crystal, molecules are linked into centrosymmetric R22(10 dimers via pairs of O—H...O hydrogen bonds and the dimers may interact through very weak by π–π interactions [centroid–centroid distance = 4.150 (1 Å]. The ethyl group is disordered over two orientations, with occupancies of 0.587 (11 and 0.413 (11.

  7. Pre-commissioning of 120 kt/a Unit for Hydrotreating Crude Coke Oven Benzene Implemented at Baoyuan Chemical Company

    Institute of Scientific and Technical Information of China (English)


    @@ The Baoyuan Chemical Company, Ltd. in Taiyuan has per-formed the precommissioning of a 120 kt/a unit for hydrotreating crude coke oven benzene. This unit is the phase II construction of the 300 kt/a crude benzene hydrotreating project, which adopts the process technology for hydrotreating crude coke oven benzene developed indepen-dently by our own efforts.

  8. Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009-12 (United States)

    Lorah, Michelle M.; Walker, Charles W.; Baker, Anna C.; Teunis, Jessica A.; Majcher, Emily H.; Brayton, Michael J.; Raffensperger, Jeff P.; Cozzarelli, Isabelle M.


    Wetlands at the Standard Chlorine of Delaware, Inc. Superfund Site (SCD) in New Castle County, Delaware, are affected by contamination with chlorobenzenes and benzene from past waste storage and disposal, spills, leaks, and contaminated groundwater discharge. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey began an investigation in June 2009 to characterize the hydrogeology and geochemistry in the wetlands and assess the feasibility of monitored natural attenuation and enhanced bioremediation as remedial strategies. Groundwater flow in the wetland study area is predominantly vertically upward in the wetland sediments and the underlying aquifer, and groundwater discharge accounts for a minimum of 47 percent of the total discharge for the subwatershed of tidal Red Lion Creek. Thus, groundwater transport of contaminants to surface water could be significant. The major contaminants detected in groundwater in the wetland study area included benzene, monochlorobenzene, and tri- and di-chlorobenzenes. Shallow wetland groundwater in the northwest part of the wetland study area was characterized by high concentrations of total chlorinated benzenes and benzene (maximum about 75,000 micrograms per liter [μg/L]), low pH, and high chloride. In the northeast part of the wetland study area, wetland groundwater had low to moderate concentrations of total chlorinated benzenes and benzene (generally not greater than 10,000 μg/L), moderate pH, and high sulfate concentrations. Concentrations in the groundwater in excess of 1 percent of the solubility of the individual chlorinated benzenes indicate that a contaminant source is present in the wetland sediments as dense nonaqueous phase liquids (DNAPLs). Consistently higher contaminant concentrations in the shallow wetland groundwater than deeper in the wetland sediments or the aquifer also indicate a continued source in the wetland sediments, which could include dissolution of DNAPLs and

  9. Modification of the structural and electronic properties of graphene by the benzene molecule adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Krasnenko, Veera, E-mail: [University of Tartu, Institute of Physics, Riia 142, Tartu (Estonia); Kikas, Jaak; Brik, Mikhail G. [University of Tartu, Institute of Physics, Riia 142, Tartu (Estonia)


    A survey of the literature data on the adsorption of benzene on graphene or carbon nanotubes indicates that the distance between the graphene sheet and benzene molecule is determined from weak van der Waals forces ({approx}3.40 Angstrom-Sign ). In our theoretical study, it was found that the benzene/graphene structure (in a specific configuration with carbon atoms located at the atop positions, stacked directly on the top of each other) forms strong covalent bonds, if the distance between the graphene and benzene is about 1.60 Angstrom-Sign . Such a short distance corresponds to about a half of the usual separation between the graphite layers. It was also shown that at such a short distance the carbon atoms of the benzene molecule move towards the graphene sheet, whereas the hydrogen atoms move in a different direction, thus breaking the benzene planar structure. In addition to the structural optimization, the calculated electronic and optical properties (significantly modified by the adsorbed benzene molecule) are presented as well.

  10. Biodegradation of High Concentrations of Benzene Vapors in a Two Phase Partition Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Ali Karimi


    Full Text Available The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580?mg/m3, a condition at which, the elimination capacity and removal efficiency were 181?g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  11. The role of C-H$\\ldots$ interaction in the stabilization of benzene and adamantane clusters

    Indian Academy of Sciences (India)

    R Mahesh Kumar; M Elango; R Parthasarathi; Dolly Vijay; V Subramanian


    In this investigation, a systematic attempt has been made to understand the interaction between adamantane and benzene using both ab initio and density functional theory methods. C-H$\\ldots$ type of interaction between C-H groups of adamantane and cloud of benzene is found as the important attraction for complex formation. The study also reveals that the methylene (-CH2) and methine (-CH) groups of adamantane interact with benzene resulting in different geometrical structures. And it is found that the former complex is stronger than the later. The diamondoid structure of adamantane enables it to interact with a maximum of four benzene molecules, each one along the four faces. The stability of the complex increases with increase in the number of benzene molecules. The energy decomposition analysis of adamantane-benzene complexes using DMA approach shows that the origin of the stability primarily arises from the dispersive interaction. The theory of atoms in molecules (AIM) supports the existence of weak interaction between the two systems. The electrostatic topography features provide clues for the mode of interaction of adamantane with benzene.

  12. Endohedral and exohedral complexes of substituted benzenes with carbon nanotubes and graphene (United States)

    Munusamy, Elango; Wheeler, Steven E.


    Non-covalent complexes of cyclohexane and a series of substituted benzenes with short carbon nanotube (CNT) models are investigated primarily at the B97-D3/TZV(2d,2p) level of theory. Understanding non-covalent interactions of arenes with CNTs is vital for the development of next-generation organic electronic materials and for harnessing CNTs as nano-reactors and vehicles for drug delivery. The interaction of benzene and cyclohexane with the interior and exterior of CNTs depends on the nanotube diameter, particularly for endohedral complexes. Both benzene and cyclohexane interact more strongly with the interior of CNTs than the outside, with benzene exhibiting stronger interactions than cyclohexane for CNTs larger than (8,8). Studies of two benzenes inside of CNTs predict the formation of one-dimensional sandwich and parallel-displaced stacks of benzenes within certain sized CNTs, which could have interesting optoelectronic properties. Concerning the impact of substituents on the interaction of benzene with CNTs, we find that electrostatic interactions do not control substituent effects. That is, the electron-donating or -withdrawing character of the substituents is not correlated with the predicted interaction energies. Moreover, substituent effects are the same for both endohedral and exohedral complexes, despite the different electronic character of the interior and exterior CNT walls. Ultimately, substituent effects in π-stacking interactions with CNTs and graphene are explained by differences in dispersion interactions between the substituents and CNT walls or graphene surface.

  13. Biodegradation of high concentrations of benzene vapors in a two phase partition stirred tank bioreactor

    Directory of Open Access Journals (Sweden)

    Karimi Ali


    Full Text Available Abstract The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580 mg/m3, a condition at which, the elimination capacity and removal efficiency were 181 g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  14. An Improved Analysis of the Sevoflurane-Benzene Structure by Chirped Pulse Ftmw Spectroscopy (United States)

    Seifert, Nathan A.; Perez, Cristobal; Zaleski, Daniel P.; Neill, Justin L.; Pate, Brooks H.; Lesarri, Alberto; Vallejo, Montserrat; Cocinero, Emilio J.; Castano, Fernando; Kleiner, Isabelle


    Recent improvements to the 2-8 GHz CP-FTMW spectrometer at University of Virginia have improved the structural and spectroscopic analysis of the sevoflurane-benzene cluster. Previously reported results, although robust, were limited to a fit of the a-type transitions of the normal species in the determination of the six-fold barrier to benzene internal rotation. Structural analysis was limited to the benzene hydrogen atom positions using benzene-d_{1}. The increased sensitivity of the new 2-8 GHz setup allows for a full internal rotation analysis of the a- and c-type transitions of the normal species, which was performed with BELGI. A fit value for V_{6} of 32.868(11) cm^{-1} is determined. Additionally, a full substitution structure of the benzene carbon atom positions was determined in natural abundance. Also, new measurements of a sevoflurane/benzene-d_{1} mixture enabled detection of 33 of the 60 possible ^{2}D / ^{13}C double isotopologues. This abundance of isotopic data, a total of 45 isotopologues, enabled a full heavy atom least-squares r_{0} structure fit for the complex, including positions for all seven fluorines in sevoflurane. N. A. Seifert, D. P. Zaleski, J. L. Neill, B. H. Pate, A. Lesarri, M. Vallejo, E. J. Cocinero, F. Castańo. 67th OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 2012, MH13.

  15. Anaerobic benzene degradation by Gram-positive sulfate-reducing bacteria. (United States)

    Abu Laban, Nidal; Selesi, Drazenka; Jobelius, Carsten; Meckenstock, Rainer U


    Despite its high chemical stability, benzene is known to be biodegradable with various electron acceptors under anaerobic conditions. However, our understanding of the initial activation reaction and the responsible prokaryotes is limited. In the present study, we enriched a bacterial culture that oxidizes benzene to carbon dioxide under sulfate-reducing conditions. Community analysis using terminal restriction fragment length polymorphism, 16S rRNA gene sequencing and FISH revealed 95% dominance of one phylotype that is affiliated to the Gram-positive bacterial genus Pelotomaculum showing that sulfate-reducing Gram-positive bacteria are involved in anaerobic benzene degradation. In order to get indications of the initial activation mechanism, we tested the substrate utilization, performed cometabolism tests and screened for putative metabolites. Phenol, toluene, and benzoate could not be utilized as alternative carbon sources by the benzene-degrading culture. Cometabolic degradation experiments resulted in retarded rates of benzene degradation in the presence of phenol whereas toluene had no effect on benzene metabolism. Phenol, 2-hydroxybenzoate, 4-hydroxybenzoate, and benzoate were identified as putative metabolites in the enrichment culture. However, hydroxylated aromatics were shown to be formed abiotically. Thus, the finding of benzoate as an intermediate compound supports a direct carboxylation of benzene as the initial activation mechanism but additional reactions leading to its formation cannot be excluded definitely.

  16. The IARC october 2009 evaluation of benzene carcinogenicity was incomplete and needs to be reconsidered. (United States)

    Infante, Peter F


    I have been familiar with the toxicological and epidemiological literature on benzene since I was a member of the NIOSH Benzene Task Force in 1975. I also am familiar with the procedures of IARC Monographs meetings from past participation, and as observer I applied this experience to the Monograph 100 F review. In October of 2009, a Working Group (WG) of the International Agency for Research on Cancer (IARC) met in Lyon, France to evaluate the available evidence for site-specific cancer to humans for 33 chemical agents and related occupations previously categorized by IARC as human carcinogens. Generally, review and discussion of the epidemiological cancer literature related to benzene was limited due to the enormous amount of material needing to be covered since the last full monograph meeting on benzene in 1981, and because 32 other chemicals and occupations were also being evaluated. Moreover, among the 33 chemicals and occupations reviewed, there was some inconsistency in the use of studies for evaluating various cancers. In some situations, consideration could have been given to the inclusion of relevant unpublished, but readily available study results. Discussion and synthesis of the animal cancer studies and mechanistic data related to specific cancers also were limited. IARC's conclusion that there is sufficient evidence for benzene to cause acute non-lymphocytic leukemia only was based on an incomplete review. IARC should schedule another monographs meeting dedicated to a complete and full review and discussion of all potential cancers related to exposure to benzene and to benzene-containing mixtures.

  17. Effect of benzene on the cerebellar structure and behavioral characteristics in rats

    Institute of Scientific and Technical Information of China (English)

    Ali Rafati; Mahboobeh Erfanizadeh; Ali Noorafshan; Saied Karbalay-Doust


    Objective:To investigate the effects of benzene on rat’s cerebellum structure and behavioral characteristics, including anxiety and motor impairment. Methods:Twenty rats were randomly allocated into two groups orally receiving distilled water and benzene (200 mg/kg/day). A total of 10 rats were used at the beginning of benzene exposure. Two rats died during benzene treatment and 8 rats remained for evaluation of the behavioral test and finally 6 rats underwent histological assessment. At the end of the 4th week, motor function and anxiety were evaluated in rotarod test and elevated plus maze, respectively. Besides, the cerebellum was dissected for structural assessment using stereological methods. Results:Performance of the benzene-treated rats in fixed and accelerating speed rotarod was impaired and their riding time (endurance) was lower compared to the control group (P=0.02). The benzene-treated rats also spent less time in the open arms and had fewer entrances to the open arms in comparison to the control group, indicating anxiety (P=0.01). The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei, total number of the Purkinje, Bergmann, Golgi, granule, neurons and glial cells of the molecular layer, and neurons and glial cells of the intracerebellar nuclei were reduced by 34%-76%in the benzene-treated rats in comparison to the distilled water group (P=0.003). The most cell loss was seen in Bergmann glia. Conclusions:The structure of cerebellum altered after benzene treatment. In addition, motor impairment and anxiety could be seen in benzene-treated rats.

  18. Effect of benzene on the cerebellar structure and behavioral characteristics in rats

    Institute of Scientific and Technical Information of China (English)

    Ali; Rafati; Mahboobeh; Erfanizadeh; Ali; Noorafshan; Saied; Karbalay-Doust


    Objective: To investigate the effects of benzene on rat’s cerebellum structure and behavioral characteristics, including anxiety and motor impairment.Methods: Twenty rats were randomly allocated into two groups orally receiving distilled water and benzene(200 mg/kg/day). A total of 10 rats were used at the beginning of benzene exposure. Two rats died during benzene treatment and 8 rats remained for evaluation of the behavioral test and finally 6 rats underwent histological assessment. At the end of the 4th week, motor function and anxiety were evaluated in rotarod test and elevated plus maze, respectively. Besides, the cerebellum was dissected for structural assessment using stereological methods.Results: Performance of the benzene-treated rats in fixed and accelerating speed rotarod was impaired and their riding time(endurance) was lower compared to the control group(P = 0.02). The benzene-treated rats also spent less time in the open arms and had fewer entrances to the open arms in comparison to the control group, indicating anxiety(P = 0.01). The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei, total number of the Purkinje, Bergmann, Golgi, granule, neurons and glial cells of the molecular layer, and neurons and glial cells of the intracerebellar nuclei were reduced by 34%-76% in the benzene-treated rats in comparison to the distilled water group(P = 0.003). The most cell loss was seen in Bergmann glia. Conclusions: The structure of cerebellum altered after benzene treatment. In addition, motor impairment and anxiety could be seen in benzene-treated rats.

  19. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian


    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  20. [Interaction between benzene and toluene in long term inhalation exposure in rats (author's transl)]. (United States)

    Gradiski, D; Bonnet, P; Duprat, P; Zissu, D; Magadur, J L; Guenier, J P


    Industrial chemicals are seldom used as pure substances; hazards resulting from exposure to mixtures have, however not been solved. Our study deals with chronic inhalation toxicity of a mixture of benzene and toluene; few studies have been completed on this subject. Our results show: - leucopenia with benzene alone, at a concentration of 50 p.p.m., that is not detectable in the presence of toluene; - metabolic variations consisting in: a decrease in the phenol urinary rate versus time with benzene alone; a sharp decrease of this rate from the third month of exposure on, in presence of toluene.

  1. Hydroxylation of benzene with hydrogen peroxide under phase-transfer conditions

    Energy Technology Data Exchange (ETDEWEB)

    Karakhanov, E.A.; Narin, S.Yu.; Filippova, T.Yu.; Dedov, A.G.


    The authors developed a method for the selective hydroxylation of benzene to phenol with hydrogen peroxide in a two-phase water-benzene system in the presence of ions of transition metals and phase-transfer catalysts. As phase-transfer catalysts they used cetyltrimethylammonium bromide, tetrabutyl-ammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, benzyltriethylammonium chloride, dibenzo-18-crown-6, benzo-15-crown-5, N-cetylpyridinium bromide, potassium didodecylsebacinate ..cap alpha..-sulfonate, and polyethylene glycols of various molecular weight. They were able to find the optimal conditions for the selective hydroxylation of benzene with hydrogen peroxide under phase-transfer catalysis conditions.

  2. Induction of granulocytic differentiation in a mouse model by benzene and hydroquinone

    Energy Technology Data Exchange (ETDEWEB)

    Hazel, B.A.; O`Connor, A.; Niculescu, R.; Kalf, G.F. [Jefferson Medical College, Philadelphia, PA (United States)


    Chronic exposure of humans to benzene causes acute myelogenous leukemia (AML). The studies presented here were undertaken to determine whether benzene, or its reactive metabolite, hydroquinone (HQ), affects differentiation of myeloblasts. Benzene or HQ administered to C57BL/6J mice specifically induced granulocytic differentiation of myeloblasts. The ability of these compounds to induce differentiation of the myeloblast was tested directly using the murine interleukin 3 (IL-3)-dependent 32D.3 (G) myeloblastic cell line, and the human HL-60 promyelocytic leukemia cell line. 37 refs., 8 figs., 4 tabs.

  3. Crystal structures of 4-meth-oxy-N-(4-methyl-phenyl)benzene-sulfonamide and N-(4-fluoro-phenyl)-4-meth-oxy-benzene-sulfonamide. (United States)

    Rodrigues, Vinola Z; Preema, C P; Naveen, S; Lokanath, N K; Suchetan, P A


    Crystal structures of two N-(ar-yl)aryl-sulfonamides, namely, 4-meth-oxy-N-(4-methyl-phen-yl)benzene-sulfonamide, C14H15NO3S, (I), and N-(4-fluoro-phen-yl)-4-meth-oxy-benzene-sulfonamide, C13H12FNO3S, (II), were determined and analyzed. In (I), the benzene-sulfonamide ring is disordered over two orientations, in a 0.516 (7):0.484 (7) ratio, which are inclined to each other at 28.0 (1)°. In (I), the major component of the sulfonyl benzene ring and the aniline ring form a dihedral angle of 63.36 (19)°, while in (II), the planes of the two benzene rings form a dihedral angle of 44.26 (13)°. In the crystal structure of (I), N-H⋯O hydrogen bonds form infinite C(4) chains extended in [010], and inter-molecular C-H⋯πar-yl inter-actions link these chains into layers parallel to the ab plane. The crystal structure of (II) features N-H⋯O hydrogen bonds forming infinite one dimensional C(4) chains along [001]. Further, a pair of C-H⋯O inter-molecular inter-actions consolidate the crystal packing of (II) into a three-dimensional supra-molecular architecture.

  4. A lack of consensus in the literature findings on the removal of airborne benzene by houseplants: Effect of bacterial enrichment (United States)

    Sriprapat, Wararat; Strand, Stuart E.


    Removal rates of benzene and formaldehyde gas by houseplants reported by several laboratories varied by several orders of magnitude. We hypothesized that these variations were caused by differential responses of soil microbial populations to the high levels of pollutant used in the studies, and tested responses to benzene by plants and soils separately. Five houseplant species and tobacco were exposed to benzene under hydroponic conditions and the uptake rates compared. Among the test plants, Syngonium podophyllum and Chlorophytum comosum and Epipremnum aureum had the highest benzene removal rates. The effects of benzene addition on populations of soil bacteria were determined using reverse transcription quantitative PCR (RT-qPCR) assays targeting microbial genes involved in benzene degradation. The total bacterial population increased as shown by increases in the levels of eubacteria 16S rRNA, which was significantly higher in the high benzene incubations than in the low benzene incubations. Transcripts (mRNA) of genes encoding phenol monooxygenases, catechol-2,3-dioxygenase and the housekeeping gene rpoB increased in all soils incubated with high benzene concentrations. Therefore the enrichment of soils with benzene gas levels typical of experiments with houseplants in the literature artificially increased the levels of total soil bacterial populations, and especially the levels and activities of benzene-degrading bacteria.

  5. Determination of benzene in soft drinks and other beverages by isotope dilution headspace gas chromatography/mass spectrometry. (United States)

    Cao, Xu-Liang; Casey, Valerie; Seaman, Steve; Tague, Brett; Becalski, Adam


    An automated, simple, and reproducible method was developed for the determination of benzene in soft drinks, based on isotope dilution headspace gas chromatography/mass spectrometry in the selected-ion monitoring mode. The method was used to assess benzene levels in samples of 124 soft drinks and beverages. Benzene was not detected in 60% of the 124 products. The average benzene levels in 6 products exceeded the Canadian maximum acceptable concentration of 5 microg/L for benzene in drinking water, and 2 of the 6 products had benzene levels above the World Health Organization guideline of 10 microg/L. The highest level of benzene, 23 microg/L, was found in a soft drink product specifically marketed to children.

  6. Benzene and MTBE Sorption in Fine Grain Sediments (United States)

    Leal-Bautista, R. M.; Lenczewski, M. E.


    The practice of adding methyl tert-butyl ether (MTBE) to gasoline started in the late 1970s and increased dramatically in the 1990s. MTBE first was added as a substitute for tetra-ethyl lead then later as a fuel oxygenate. Although the use of MTBE has resulted in significant reduction in air pollution, it has become a significant groundwater contaminant due to its high solubility in water, high environmental mobility, and low potential for biodegradation. A recent report (1999-2001) by the Metropolitan Water District of Southern California in collaboration with United State Geological Survey and the Oregon Health and Science University found that MTBE was the second most frequent detected volatile organic compound in groundwater. In Illinois, MTBE has been found in 26 of the 1,800 public water supplies. MTBE has also been blended in Mexico into two types of gasoline sold in the country by the state oil company (PEMEX) but is not monitored in groundwater at this time. Early research on MTBE considered it unable to adsorb to soils and sediments, however, by increasing the organic matter and decreasing the size of the grains (silts or clays) this may increase sorption. The objective of this study is to determine if fine grained materials have the potential for sorption of MTBE due to its high specific surface area (10-700 m 2/g) and potentially high organic matter (0.5-3.8%). The experiment consisted of sorption isotherms to glacial tills from DeKalb, Illinois and lacustrine clays from Chalco, Mexico. Experiments were performed with various concentrations of MTBE and benzene (10, 50, 100, 500 and 1000 ug/L) at 10° C and 25° C. Results showed a range of values for the distribution coefficient (Kd, linear model). At 10° C the Kd value for MTBE was 0.187 mL/g for lacustrine clay while the glacial loess had a value of 0.009 mL/g. The highest Kd values with MTBE were 0.2859 mL/g for organic rich lacustrine clays and 0.014 mL/g for glacial loess at 25° C. The highest

  7. Subchronic inhalation toxicity of benzene in rats and mice. (United States)

    Ward, C O; Kuna, R A; Snyder, N K; Alsaker, R D; Coate, W B; Craig, P H


    A subchronic inhalation toxicity study of benzene was conducted in CD-1 mice and Sprague-Dawley rats. Four groups of animals consisting of 150 mice and 50 rats/sex each were exposed to concentrations of 1, 10, 30, and 300 ppm benzene vapor, 6 hours/day, 5 days/week, for 13 weeks. Additional groups of mice and rats, of equal size, were exposed under similar conditions to filtered air and served as control groups. Thirty mice and 10 rats/sex in each group were sacrificed after 7, 14, 28, 56, and 91 days of treatment. Criteria used to evaluate exposure-related effects included behavior, body weights, organ weights, clinical pathology, gross pathology, and histopathology. Fifty animals per sex of each species were exposed concurrently for cytogenetic studies. In addition, blood serum was obtained for immunological assays. The results of these two studies will be reported separately. No consistent exposure-related trends were seen in the clinical observations and body weight data. Exposure-related clinical pathology changes were seen in the high-level (300 ppm) animals of both species. In the mice, these changes included decreases in hematocrit, total hemoglobin, erythrocyte count, leukocyte count, platelet count, myeloid/erythroid ratios, and percentage of lymphocytes. Mean cell volume, mean cell hemoglobin, glycerol lysis time, and the incidence and severity of red cell morphologic changes were increased in the mice. In the rats, decreased lymphocyte counts and a relative increase in neutrophil percentages were the only exposure-related clinical pathology alterations. Histopathologic changes were present in the thymus, bone marrow, lymph nodes, spleen, ovaries, and testes of mice exposed to 300 ppm and in most cases the incidence and severity of the lesions were greater in the males. These changes in the testes and ovaries at 300 ppm were also seen at lower concentrations, but they were of doubtful biological significance. In rats, the only exposure-related lesion

  8. Kinetics of Liquid-Phase Hydrogenation of Benzene in a Metal Hydride Slurry System Formed by M1Ni5 and Benzene

    Institute of Scientific and Technical Information of China (English)

    代世耀; 徐国华; 安越; 陈长聘; 陈立新; 王启东


    The kinetics of liquid-phase hydrogenation of benzene in misch metal nickel-five (M1Ni5) and benzene slurry system was studied by investigating the influences of the reaction temperature, pressure, alloy concentration and stirring speed on the mass transfer-reaction processes inside the slurry. The results show that the whole process is controlled by the reaction at the surface of the catalyst. The mass transfer resistance at gas-liquid interface and that from the bulk liquid phase to the surface of the catalyst particles are negligible. The apparent reaction rate is zero order for benzene concentration and first order for hydrogen concentration in the liquid phase. The kinetic model obtained fits the experimental data very well. The apparent activation energy of the hydrogen absorption reaction of M1Ni5-C6H6 slurry system is 42.16 kJ·mo1-1.

  9. Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens

    DEFF Research Database (Denmark)

    Zhang, Tian; Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar;


    Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter...

  10. Biomonitoring of benzene and toluene in human blood by headspace-solid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Schimming, E.; Levsen, K. [Fraunhofer-Institut fuer Toxikologie und Aerosolforschung (ITA), Hannover (Germany); Koehme, C.; Schuermann, W. [Medizinische Hochschule Hannover (Germany). Abt. fuer Pneumologie


    A simple and rapid method for the determination of benzene and toluene in whole blood by headspace-solid-phase microextraction (HS-SPME) is described. Using SPME fibres coated with 65 {mu}m carboxene/polydimethylsiloxane, limits of quantification (LOQ) of 5 ng/L for benzene and 25 ng/L for toluene are achieved. As a result of its large linear range (i.e. 5-5000 ng/L for benzene) the method is suitable for biomonitoring of both occupationally and environmentally exposed people. The reproducibility of the determination of benzene is {<=} 8%. An interlaboratory comparison demonstrated that the method proposed here compares favorably with existing methods (dynamic headspace, purge and trap). (orig.) With 2 figs., 2 tabs., 10 refs.

  11. Further evidence of benzene carcinogenicity. Results on Wistar rats and Swiss mice treated by ingestion. (United States)

    Maltoni, C; Conti, B; Perino, G; Di Maio, V


    Wistar rats and Swiss mice were treated by ingestion (stomach tube) with benzene in olive oil at a dose of 500 and 0 mg/kg b.w. once daily, 4-5 days weekly, for 104 weeks (rats) or for 78 weeks (mice). In Wistar rats, benzene caused Zymbal gland carcinomas, carcinomas of the oral cavity, and carcinomas of the nasal cavities, and an increase in the incidence of total malignant tumors. In Swiss mice, benzene produced Zymbal gland carcinomas and dysplasias and an increase in the incidence of mammary carcinomas (in females), lung tumors, and total malignant tumors. These experiments further confirm that benzene is a multipotential carcinogen as was shown before by long-term bioassays performed on Sprague-Dawley rats in the same Experimental Unit.


    and ferrocenylphenol with phenol and p-hydroxydiphenyl (p- phenylphenol ), indicating that the ferrocenyl group introduced into the benzene ring behaves as a distinctly expressed substitute of the first order.

  13. Parallel interactions at large horizontal displacement in pyridine-pyridine and benzene-pyridine dimers. (United States)

    Ninković, Dragan B; Andrić, Jelena M; Zarić, Snežana D


    A study of crystal structures from the Cambridge Structural Database (CSD) and DFT calculations reveals that parallel pyridine-pyridine and benzene-pyridine interactions at large horizontal displacements (offsets) can be important, similar to parallel benzene-benzene interactions. In the crystal structures from the CSD preferred parallel pyridine-pyridine interactions were observed at a large horizontal displacement (4.0-6.0 Å) and not at an offset of 1.5 Å with the lowest calculated energy. The calculated interaction energies for pyridine-pyridine and benzene-pyridine dimers at a large offset (4.5 Å) are about 2.2 and 2.1 kcal mol(-1), respectively. Substantial attraction at large offset values is a consequence of the balance between repulsion and dispersion. That is, dispersion at large offsets is reduced, however, repulsion is also reduced at large offsets, resulting in attractive interactions.

  14. Influence of temperature and humidity on the detection of benzene vapor by piezoelectric crystal sensor

    CERN Document Server

    Han, Chan-Hyon; Yun, Jong-Ho; Sin, Kye-Ryong


    The effects of temperature and humidity on the estimation of air pollution by benzene by using the piezoelectric crystal gas sensor were studied. Polyvinylchloride films were used as substrate for the immobilization of polymethylphenylsiloxane onto the electrode surface of the piezoelectric crystal. The sensing layer consisting of polymethylphenylsiloxane and polyvinylchloride was used for real-time monitoring of benzene, one of the atmospheric pollutants. According to the humidity from 35% to 75%, the upper limit of detection by this sensor was decreased and the response time and frequency recovery time for detecting benzene were long. On the other hand, as increasing the temperature, the response time and the frequency recovery time of the sensor were short, but its sensitivity got worse. The models for the correlation between the benzene concentration and temperature (or humidity) were presented.

  15. Benzaldehyde in cherry flavour as a precursor of benzene formation in beverages. (United States)

    Loch, Christine; Reusch, Helmut; Ruge, Ingrid; Godelmann, Rolf; Pflaum, Tabea; Kuballa, Thomas; Schumacher, Sandra; Lachenmeier, Dirk W


    During sampling and analysis of alcohol-free beverages for food control purposes, a comparably high contamination of benzene (up to 4.6μg/L) has been detected in cherry-flavoured products, even when they were not preserved using benzoic acid (which is a known precursor of benzene formation). There has been some speculation in the literature that formation may occur from benzaldehyde, which is contained in natural and artificial cherry flavours. In this study, model experiments were able to confirm that benzaldehyde does indeed degrade to benzene under heating conditions, and especially in the presence of ascorbic acid. Analysis of a large collective of authentic beverages from the market (n=170) further confirmed that benzene content is significantly correlated to the presence of benzaldehyde (r=0.61, pbenzaldehyde in combination with ascorbic acid should be avoided.

  16. Benzene Oxidation on Boron-Doped Diamond Electrode: Electrochemical-Impedance Study of Adsorption Effects

    Directory of Open Access Journals (Sweden)

    Yuri Pleskov


    Full Text Available Benzene oxidation at a boron-doped diamond anode in 0.5 M K2SO4 aqueous solution is studied by cyclic voltammetry and electrochemical impedance spectroscopy. It is shown by measurements of differential capacitance and anodic current that in the ideal-polarizability potential region benzene either is not adsorbed at the diamond electrode or the benzene adsorption does not affect its capacitance. At more positive potentials, the adsorption of some intermediate of the benzene oxidation occurs at the electrode. The intermediate partially blocks the electrode surface and lowers the anodic current. The very fact of the electrode surface blocking is reflected in the complex-plane presentation of the impedance-potential plots.

  17. Symmetry forbidden vibronic spectra and internal conversion in benzene. (United States)

    Li, Jun; Lin, Chih-Kai; Li, Xiang Yuan; Zhu, Chao Yuan; Lin, Sheng Hsien


    The spectra of symmetry-forbidden transitions and internal conversion were investigated in the present work. Temperature dependence was taken into account for the spectra simulation. The vibronic coupling, essential in the two processes, was calculated based on the Herzberg-Teller theory within the Born-Oppenheimer approximation. The approach was employed for the symmetry-forbidden absorption/fluorescence, and internal conversion between 1(1)A(1g) and 1(1)B(2u) states in benzene. Vibrational frequencies, normal coordinates, electronic transition dipole moments, and non-adiabatic coupling matrix elements were obtained by ab initio quantum chemical methods. The main peaks, along with the weak peaks, were in good agreement with the observed ones. The rate constant of the 1(1)A(1g)← 1(1)B(2u) internal conversion was estimated within the order of 10(3) s(-1). This could be regarded as the lower limit (about 4.8 × 10(3) s(-1)) of the internal conversion. It is stressed that the distortion effect was taken into account both in the symmetry-forbidden absorption/fluorescence, and the rate constants of internal conversion in the present work. The distortion effects complicate the spectra and increase the rate constants of internal conversion.

  18. (η6-Benzenedichlorido(dicyclohexylphenylphosphaneruthenium(II benzene sesquisolvate

    Directory of Open Access Journals (Sweden)

    Alfred Muller


    Full Text Available The asymmetric unit of the title compound, [RuCl2(C6H6(C18H27P]·1.5C6H6, contains one molecule of the RuII complex and one and a half solvent molecules as one of these is located about a centre of inversion. The RuII atom has a classical three-legged piano-stool environment being coordinated by an η6-benzene ligand [Ru—centroid = 1.6964 (6 Å], two chloride ligands with an average Ru—Cl bond length of 2.4138 (3 Å and a dicyclohexylphenylphosphane ligand [Ru—P = 2.3786 (3 Å]. The effective cone angle for the phosphane was calculated to be 158°. In the crystal, weak C—H...Cl hydrogen bonds link the RuII complexes into centrosymmetric dimers. The crystal packing exhibits intra- and intermolecular C—H...π interactions resulting in a zigzag pattern in the [101] direction.

  19. Spectroscopic studies of cryogenic fluids: Benzene in propane (United States)

    Nowak, R.; Bernstein, E. R.


    Energy shifts and bandwidths for the 1B2u↔1A1g optical absorption and emission transitions of benzene dissolved in propane are presented as a function of pressure, temperature, and density. Both absorption and emission spectra exhibit shifts to lower energy as a function of density, whereas no shifts are observed if density is kept constant and temperature and pressure are varied simultaneously. Density is thus the fundamental microscopic parameter for energy shifts of optical transitions. The emission half-width is a linear function of both temperature and pressure but the absorption half-width is dependent only upon pressure. These results are interpreted qualitatively in terms of changes occurring in the intermolecular potentials of the ground and excited states. Both changes in shape of and separation between the ground and excited state potentials are considered as a function of density. Classical dielectric (Onsager-Böttcher), microscopic dielectric (Wertheim) and microscopic quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute electronic spectra are compared with the experimental results. Calculations suggest limited applicability of dielectric theories but good agreement between experiment and microscopic theory. The results demonstrate the usefulness of cryogenic solutions for high pressure, low temperature spectroscopic studies of liquids.


    Energy Technology Data Exchange (ETDEWEB)

    Sivaraman, B.; Mukherjee, R.; Subramanian, K. P.; Banerjee, S. B., E-mail: [Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad (India)


    Propargyl alcohol (CHCCH{sub 2}OH) is a known stable isomer of the propenal (CH{sub 2}CHCHO) molecule that was reported to be present in the interstellar medium (ISM). At astrochemical conditions in the laboratory, icy layers of propargyl alcohol grown at 85 K were irradiated by 2 keV electrons and probed by a Fourier Transform InfraRed spectrometer in the mid-infrared (IR) region, 4000-500 cm{sup –1}. Propargyl alcohol ice under astrochemical conditions was studied for the first time; therefore, IR spectra of reported amorphous (85 K) and crystalline (180 K) propargyl alcohol ices can be used to detect its presence in the ISM. Moreover, our experiments clearly show benzene (C{sub 6}H{sub 6}) formation to be the major product from propargyl alcohol irradiation, confirming the role of propargyl radicals (C{sub 3}H{sub 3}) formed from propargyl alcohol dissociation that was long expected based on theoretical modeling to effectively synthesize C{sub 6}H{sub 6} in the interstellar icy mantles.

  1. Theoretical study of the adsorption of benzene on coinage metals

    Directory of Open Access Journals (Sweden)

    Werner Reckien


    Full Text Available The adsorption of benzene on the M(111, M(100 and M(110 surfaces of the coinage metals copper (M = Cu, silver (M = Ag and gold (M = Au is studied on the basis of density functional theory (DFT calculations with an empirical dispersion correction (D3. Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE in combination with different versions of the dispersion correction (D3 and D3(BJ are compared. PBE-D3, PBE-D3(BJ and RPBE-D3 give similar results which exhibit a good agreement with experimental data. RevPBE-D3 and RevPBE-D3(BJ tend to overestimate adsorption energies. The inclusion of three-center terms (PBE-D3(ABC leads to a slightly better agreement with the experiment in most cases. Vertical adsorbate–substrate distances are calculated and compared to previous theoretical results. The observed trends for the surfaces and metals are consistent with the calculated adsorption energies.

  2. Phytotoxicity of chlorinated benzenes to Typha angustifolia and Phragmites communis. (United States)

    Ma, Xingmao; Havelka, Megan M


    Healthy growth of plants is a prerequisite for successful application of phytoremediation technologies. Typha angustifolia and Phragmites communis are common wetland plants and have shown potential for phytoremediation of hexachlorobenzene (HCB). However, the lack of phytotoxicity data impedes their application in field sites. This study investigated the phytotoxicity of HCB, and its two metabolites: 1,3,5-trichlorobenzene (1,3,5-TCB) and 1,4-dichlorobenzene (1,4-DCB) to Typha and the phytotoxicity of 1,3,5-TCB to Phragmites. The phytotoxicity of 1,3,5-TCB is species-dependent, with Typha demonstrating significantly higher tolerance than Phragmites. The concentration of 1,3,5-TCB causing zero growth of Phragmites was determined to be 1575 mg TCB/kg dry sediment. The concentration has to be doubled to completely inhibit the growth of Typha. Adverse effects of chlorinated benzenes in sediments on Typha increased with decreasing chlorine atoms. The concentrations causing zero growth of Typha are 5765 mg HCB/kg dry soil, 3157 mg 1,3,5-TCB/kg dry soil, and 1325 mg 1,4-DCB/kg dry soil. The higher toxicity of 1,4-DCB than 1,3,5-TCB and HCB in sediment was ascribed to its higher availability and easiness to be taken up by plants. The conclusion was supported by both growth rate calculations and plant height measurements. (c) 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.

  3. Treatment Of Scabies With 1% Gamma Benzene Hexachloride

    Directory of Open Access Journals (Sweden)

    Srinivas C.R


    Full Text Available We assessed the efficacy of 3 different treatment modalities with gamma benzene hexachloride (GBH in an institutional outbreak of scabies. The 92 female inmates, between 5-18 years, in a state home with scabies and the supervisory staff were educated about the disease and treatment. As most inmates had secondary pyoderma, all were treated by a course of trimethoprim 80 mg; sulpha methoxazole 400 mg twice a day for 5 days. 250 lit of 1% GBH solution were prepared from 2.5 kg of GBH powder and were used for all the three treatment modalities. Forty-five girls were treated by GBH bath, each girl was allowed to soak in the tub for one minute and then allowed to dry; 34 girls were sprayed using a plastic hand spray and 23 were treated by paint brush application. Treatment was repeated after 1 week and reviewed after 2 and 6 weeks. On 1st visit, 4 girls of bath group showed few a symptomatic popular lesions over the hands and were retreated. All others were free of both symptoms and lesions. On second visit, all were free of lesions. All the three modes of drug delivery were effective. The bathtub offered privacy and it was quicker than both spraying and painting. However, the expense incurred per patient for bath was Rs.57 whereas it was only Rs.4 and Rs.5 for spray and paint brush application respectively.

  4. Experimental research on benzene detection using ion mobility spectrometer with a laser ionization source

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-yun; KONG Xiang-he; JI Ren-dong; ZHANG Shu-dong


    An ion mobility spectrometer equipped with a laser ionization source is used for the sensitive detection of benzene.Mobility spectra of the benzene are presented.We also discussed the mobility spectra at various concentrations and drift voltages.Detection limits are determined to be in the upper ppbv range.In the end,the advantages and possibilities of this technique are briefly discussed.

  5. Human risk assessment of benzene after a gasoline station fuel leak

    Directory of Open Access Journals (Sweden)

    Miriam dos Anjos Santos


    Full Text Available OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals, probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L.The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals. The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk. Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

  6. Molecular dynamics simulation of benzene in graphite and amorphous carbon slit pores. (United States)

    Fomin, Yu D


    It is well known that confining a liquid into a pore strongly alters the liquid behavior. Investigations of the effect of confinement are of great importance for many scientific and technological applications. Here, we present a study of the behavior of benzene confined in carbon slit pores. Two types of pores are considered-graphite and amorphous carbon ones. We show that the effect of different pore structure is of crucial importance for the benzene behavior.

  7. Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS


    José A. Sousa; Domingues, Valentina F.; Rosas, Mónica S.; Ribeiro, Susana; Alvim-Ferraz, Maria da Conceição M.


    The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized ...

  8. Activated-sludge nitrification in the presence of linear and branched-chain alkyl benzene sulfonates. (United States)

    Baillod, C R; Boyle, W C


    The effects of biodegradable linear alkyl benzene sulfonate and branched-chain alkyl benzene sulfonate detergents on activated-sludge nitrification were investigated by administering a synthetic waste containing up to 23 mg of each detergent per liter to eight bench-scale, batch, activated-sludge units. It was found that both detergents tended to promote complete oxidation of ammonia to nitrate, whereas control units produced approximately equal amounts of nitrite and nitrate. Various hypotheses are offered to explain the phenomenon.

  9. Investigation into adsorption and photocatalytic degradation of gaseous benzene in an annular fluidized bed photocatalytic reactor. (United States)

    Geng, Qijin; Tang, Shankang; Wang, Lintong; Zhang, Yunchen


    The adsorption and photocatalytic degradation of gaseous benzene were investigated considering the operating variables and kinetic mechanism using nano-titania agglomerates in an annular fluidized bed photocatalytic reactor (AFBPR) designed. The special adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of benzene were determined by linear regression analysis at various gas velocities and relative humidities (RH). Based on a series of photocatalytic degradation kinetic equations, the influences of operating variables on degradation efficiency, apparent reaction rate coefficient and half-life were explored. The findings indicated that the operating variables have obviously influenced the adsorption/photocatalytic degradation and corresponding kinetic parameters. In the photocatalytic degradation process, the relationship between photocatalytic degradation efficiency and RH indicated that water molecules have a dual-function which was related to the structure characteristics of benzene. The optimal operating conditions for photocatalytic degradation of gaseous benzene in AFBPR were determined as the fluidization number at 1.9 and RH required related to benzene concentration. This investigation highlights the importance of controlling RH and benzene concentration in order to obtain the desired synergy effect in photocatalytic degradation processes.

  10. Degradation of Benzene by Using a Silent-Packed Bed Hybrid Discharge Plasma Reactor (United States)

    Jiang, Nan; Lu, Na; Li, Jie; Wu, Yan


    In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield (EY) were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter (space velocity) was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.

  11. Volatilization of monoaromatic compounds (benzene, toluene, and xylenes; BTX) from gasoline: effect of the ethanol. (United States)

    Cagliari, Jóice; Fedrizzi, Francieli; Rodrigues Finotti, Alexandra; Echevenguá Teixeira, Cláudia; do Nascimento Filho, Irajá


    The main objective of present study was to assess the evaporation profile of monoaromatic compounds, namely, benzene, toluene, and xylenes (BTX) from gasoline-ethanol-blend fuels. The vapors from two river sand columns contaminated with gasoline and gasoline-ethanol were monitored for 77 d. Standards mixtures (batch tests) of benzene, toluene, and xylenes with different ethanol contents were also analyzed for evaporation rates studies. The instrumental analysis was performed via gas chromatography. The concentration of benzene in the vapor phase of the gasoline-ethanol column was decreased by 89.09%, considering the entire experimental period, whereas the toluene and xylenes concentrations were increased by 239.34 and 251.78%, respectively. In the batch tests, the benzene concentration in the vapor phase varied from 0.4 to 0.9 mg/L for ethanol concentrations (v/v) of 5 and 10%, respectively. For ethanol concentrations higher than 10%, no important changes in the benzene concentration were observed. The toluene exponentially increases between 20 and 30% ethanol concentration. and the maximum concentration of xylenes was observed when the ethanol concentration was 20% (v/v). These results suggest that the benzene evaporation behavior is preferentially affected by the interactions among ethanol and other aromatic compounds rather than the ethanol concentration itself. The evaporation behaviors of toluene and xylenes are directly dependent on the ethanol content.

  12. Investigation on minimum ignition energy of mixtures of α-pinene-benzene/air. (United States)

    Coudour, B; Chetehouna, K; Rudz, S; Gillard, P; Garo, J P


    Minimum ignition energies (MIE) of α-pinene-benzene/air mixtures at a given temperature for different equivalence ratios and fuel proportions are experimented in this paper. We used a cylindrical chamber of combustion using a nanosecond pulse at 1,064 nm from a Q-switched Nd:YAG laser. Laser-induced spark ignitions were studied for two molar proportions of α-pinene/benzene mixtures, respectively 20-80% and 50-50%. The effect of the equivalence ratio (Φ) has been investigated for 0.7, 0.9, 1.1 and 1.5 and ignition of fuel/air mixtures has been experimented for two different incident laser energies: 25 and 33 mJ. This study aims at observing the influence of different α-pinene/benzene proportions on the flammability of the mixture to have further knowledge of the potential of biogenic volatile organic compounds (BVOCs) and smoke mixtures to influence forest fires, especially in the case of the accelerating forest fire phenomenon (AFF). Results of ignition probability and energy absorption are based on 400 laser shots for each studied fuel proportions. MIE results as functions of equivalence ratio compared to data of pure α-pinene and pure benzene demonstrate that the presence of benzene in α-pinene-air mixture tends to increase ignition probability and reduce MIE without depending strongly on the α-pinene/benzene proportion.

  13. Determination of benzene residues in recycled polyethylene terephthalate (PETE) by dynamic headspace-gas chromatography. (United States)

    Komolprasert, V; Hargraves, W A; Armstrong, D J


    A dynamic headspace-gas chromatography (HS/GC) method was developed to quantitate benzene in recycled PETE material derived from 21 PETE beverage bottles. The analytical system consisted of a purge-and-trap apparatus which was interfaced directly with a gas chromatograph/flame ionization detector. Cryofocusing and non-cryofocusing GC systems were used. The technique was applied to spiked PETE test samples which were prepared at various benzene concentrations ranging from 100 ppb to 117 ppm. The initial spiked benzene concentration in the PETE test samples was determined gravimetrically. The HS/GC technique was limited by the slow desorption rate of benzene from the PETE matrix; as a result, multipurges were performed at 60 degrees C. Regression analysis was done on the multipurge data to develop a desorption model which would predict the total amount of benzene in the PETE. The calculated results agreed with the experimental recoveries within +/- 10%. Recovery depended on the initial benzene level in the PETE and ranged from 70 to 90% after the first five purges.

  14. Immunotoxicological effects of benzene inhalation in male Sprague-Dawley rats. (United States)

    Robinson, S N; Shah, R; Wong, B A; Wong, V A; Farris, G M


    The inhalation of benzene is toxic to various components of the immunologic system in rodents. Spleen and thymus weights, total spleen and femur marrow cell counts, enumeration of spleen B- and T-lymphocytes, and an assessment of humoral immunocompetence, were used to evaluate the immunotoxicity of benzene in male Sprague-Dawley rats. Rats were exposed to 0, 30, 200 or 400 ppm benzene for 6 h/day, 5 days/week for 2 or 4 weeks. An early indicator of immunotoxicity was a reduction in the number of B-lymphocytes after 2 weeks of 400 ppm. After 4 weeks of 400 ppm, there was a reduction in thymus weight and spleen B-, CD4+/CD5+ and CD5+ T-lymphocytes. Rats exposed to 30, 200 or 400 ppm benzene for 2 or 4 weeks and challenged with sheep red blood cells developed a humoral response comparable to that of the control (0 ppm) animals. Enumeration of spleen T- and B-lymphocytes in rats exposed to benzene and challenged with SRBC showed only a transient reduction in spleen B-lymphocytes after 2 weeks of exposure to 400 ppm. These data suggest that there are no immunotoxicological effects of exposure to 200 ppm benzene or less, in rats exposed for 6 h/day, 5 days/week for 2 or 4 weeks.

  15. Geogenic sources of benzene in aquifers used for public supply, California (United States)

    Belitz, Kenneth; Landon, Matthew K.


    Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium 1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

  16. Sampling of benzene in tar matrices from biomass gasification using two different solid-phase sorbents. (United States)

    Osipovs, Sergejs


    Biomass tar mainly consists of stable aromatic compounds such as benzene and polyaromatic hydrocarbons, benzene being the biggest tar component in real biomass gasification gas. For the analysis of individual tar compounds, the solid-phase adsorption method was chosen. According to this method, tar samples are collected on a column with an amino-phase sorbent. With a high benzene concentration in biomass tar, some of the benzene will not be collected on the amino-phase sorbent. To get over this situation, we have installed another column with activated charcoal which is intended for collection of volatile organic compounds, including benzene, after the column with the amino-phase sorbent. The study of maximal adsorption amounts of various compounds on both adsorbents while testing different sampling volumes led to the conclusion that benzene is a limiting compound. The research proved that the use of two sorbents (500 mg + 100 mg) connected in series allows for assessment of tar in synthesis gas with a tar concentration up to 30-40 g m(-3), which corresponds to the requirements of most gasifiers.

  17. Treatment of co-mingled benzene, toluene and TCE in groundwater. (United States)

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


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

  18. Modifications of benzene myelotoxicity and metabolism by phenobarbital, SKF-252A and 3-methylcholanthrene

    Energy Technology Data Exchange (ETDEWEB)

    Gill, D.P.; Kempen, R.R.; Nash, J.B.; Ellis, S.


    It has recently been suggested that the primary myelotoxic species generated from benzene is not produced directly from the parent compound, but from phenol or an even later metabolite. Several compounds that alter the activities of microsomal oxidative and conjugating enzymes were studied for their effects on benzene's myelotoxicity and metabolism. Phenobarbital (PB) protected animals from leucopnia and increased both to total amount of phenol as well as the amount of unconjugated phenol excreted in the urine. SKF-525A had no effect on the leucopenia, whereas it reduced the conversion of benzene to phenol without changing the excretion of unconjugated phenol. 3-Methylcholanthrene also did not prevent the leucopenia, but it did increase the conversion of benzene to phenol and the amount of unconjugated phenol excreted during the first days of the experiment. These data indicate that the early phases of benzene's metabolism may be modulated by the drug pretreatments employed, but myelotoxicity was abated only by PB. We conclude that the marrow effect of benzene is due to a metabolic product other than phenol and, furthermore that the formation of this toxic principle is not strictly dependent on the rate of phenol production.

  19. Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Dougal, R.A. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Electrical and Computer Engineering


    High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a {sup 60}Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of {sup 60}Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 {mu}g/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. {sup 60}Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants.

  20. Single-molecule conductance through multiple π-π-stacked benzene rings determined with direct electrode-to-benzene ring connections. (United States)

    Schneebeli, Severin T; Kamenetska, Maria; Cheng, Zhanling; Skouta, Rachid; Friesner, Richard A; Venkataraman, Latha; Breslow, Ronald


    Understanding electron transport across π-π-stacked systems will help to answer fundamental questions about biochemical redox processes and benefit the design of new materials and molecular devices. Herein we employed the STM break-junction technique to measure the single-molecule conductance of multiple π-π-stacked aromatic rings. We studied electron transport through up to four stacked benzene rings held together in an eclipsed fashion via a paracyclophane scaffold. We found that the strained hydrocarbons studied herein couple directly to gold electrodes during the measurements; hence, we did not require any heteroatom binding groups as electrical contacts. Density functional theory-based calculations suggest that the gold atoms of the electrodes bind to two neighboring carbon atoms of the outermost cyclophane benzene rings in η(2) fashion. Our measurements show an exponential decay of the conductance with an increasing number of stacked benzene rings, indicating a nonresonant tunneling mechanism. Furthermore, STM tip-substrate displacement data provide additional evidence that the electrodes bind to the outermost benzene rings of the π-π-stacked molecular wires.

  1. Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Eva M., E-mail: [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Kuschk, Peter; Fazekas, Helga [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Grathwohl, Peter [Center of Applied Geoscience, University of Tuebingen, Hoelderlinstr. 12, 72074 Tuebingen (Germany); Kaestner, Matthias [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany)


    In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m{sup 2}/d, 97/112 mg/m{sup 2}/d, and 1167/1342 mg/m{sup 2}/d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique. - Highlights: > BTEX compounds contaminated groundwater can be efficiently treated by CWs. > The removal efficiency depended on CW type, season and contaminant. > The plant root mat revealed better treatment results than the gravel filter CW. > Best results achieved by the plant root mat (99% benzene concentration decrease). > Stable isotope analysis and MPN indicated high benzene remediation potential. - Gravel bed constructed wetlands and a plant root mat system efficiently eliminated fuel hydrocarbons (benzene, MTBE) and ammonia-N from groundwater at a pilot-scale.

  2. Penetration of benzene, toluene and xylenes contained in gasolines through human abdominal skin in vitro. (United States)

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


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

  3. Characterization of changes in gene expression and biochemical pathways at low levels of benzene exposure.

    Directory of Open Access Journals (Sweden)

    Reuben Thomas

    Full Text Available Benzene, a ubiquitous environmental pollutant, causes acute myeloid leukemia (AML. Recently, through transcriptome profiling of peripheral blood mononuclear cells (PBMC, we reported dose-dependent effects of benzene exposure on gene expression and biochemical pathways in 83 workers exposed across four airborne concentration ranges (from 10 ppm compared with 42 subjects with non-workplace ambient exposure levels. Here, we further characterize these dose-dependent effects with continuous benzene exposure in all 125 study subjects. We estimated air benzene exposure levels in the 42 environmentally-exposed subjects from their unmetabolized urinary benzene levels. We used a novel non-parametric, data-adaptive model selection method to estimate the change with dose in the expression of each gene. We describe non-parametric approaches to model pathway responses and used these to estimate the dose responses of the AML pathway and 4 other pathways of interest. The response patterns of majority of genes as captured by mean estimates of the first and second principal components of the dose-response for the five pathways and the profiles of 6 AML pathway response-representative genes (identified by clustering exhibited similar apparent supra-linear responses. Responses at or below 0.1 ppm benzene were observed for altered expression of AML pathway genes and CYP2E1. Together, these data show that benzene alters disease-relevant pathways and genes in a dose-dependent manner, with effects apparent at doses as low as 100 ppb in air. Studies with extensive exposure assessment of subjects exposed in the low-dose range between 10 ppb and 1 ppm are needed to confirm these findings.

  4. Assessment of Benzene Exposures in the Working Environment at Gasoline Stations

    Directory of Open Access Journals (Sweden)

    Sunisa Chaiklieng


    Full Text Available This study aimed to investigate benzene exposure in the working environment of workers at gasoline stations. Ambient air (n=20 and inhaled air samples (n=101 of benzene were collected in the city of Khon Kaen, Thailand and analyzed with gas chromatography (GC-FID. Data records were also kept of the amounts of various petroleum products sold. The results of inhaled air benzene indicated the range concentration from 0.03 ppb to 65.71 ppb and showed significant differences between concentrations of each zone (p<0.05. The highest mean concentration was found in suburban stations (35.55 ppb, followed by urban stations (18.19 ppb, and rural stations (2.52 ppb. The highest mean concentration of ambient air was found in urban stations (45.55 ppb. Regarding different job functions, the benzene concentration of fueling workers in the inhalation zone (27.29 ppb was significantly higher than that of cashiers (0.56 ppb. The amounts of petroleum products with high benzene content sold were relatively consistent with inhaled benzene concentration, indicated by the significant differences between suburban and rural zones (p<0.05. In conclusion, this study found the inhaled air benzene concentration ranged 0.03 to 65.71 ppb depending on locations and job functions of workers. Therefore, workers should be protected of adversely affected health from long-term exposure by training on safe working practice and awareness of the different risks associated with their job functions, locations of stations and daily amounts of petroleum products sold.

  5. Benzene and lead exposure assessment among occupational bus drivers in Bangkok traffic

    Institute of Scientific and Technical Information of China (English)



    Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region(BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further subdivided into four age groups( 16-25, 26-35, 36-45 and 46-55 years old) to monitor the age-related exposure effects. A total of 12unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure.During the monitoring period, benzene and lead levels at Yaowarat Road was C6H6: 42.46 + 3.88 μg/m3 , Pb: 0.29 + 0.03 μg/m3 and decreased to C6 H6: 33.5 ± 1.35 μg/m3 , Pb: O. 13 + 0.01 μg/m3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations ( P < 0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile emissions.The analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission.

  6. Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS. (United States)

    Sousa, José A; Domingues, Valentina F; Rosas, Mónica S; Ribeiro, Susana O; Alvim-Ferraz, Conceiçao M; Delerue-Matos, Cristina F


    The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 μg m⁻³) and during the unloading of gasoline the achieved concentration was 8371 μg m⁻³; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 μg m⁻³ except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 μg m⁻³) than in coffee shops where this is forbidden (4 μg m⁻³). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene.

  7. Liquid-phase benzene isopropylation using alumina solid lewis superacid-supported platinum catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, K.; Honda, K.; Kitahara, D.; Miyamoto, M.; Shiga, M.; Ayame, A. [Muroran Inst. of Tech., Hokkaido (Japan)


    Supporting platinum on alumina solid Lewis superacid (AmLSA; J. C. S., Chem. Commun., 645 (1989)) was prepared by using of the in situ CVD technique at 773 K with Ar{sup +}-sputtered platinum fine particles and dry chlorine, followed by reduction with hydrogen at 673 K. The AmLSA-supported platinum catalyst (Pt/AmLSA) was applied to isopropylation of benzene with propene in the hydrogen stream at ambient temperature, using a semibatch reactor. Products were mono-, di-, tri-, and tetra-isopropylbenzenes. Conversion of propene to propane was below 1 %, and a trace amount of cyclohexane from benzene was also observed. Deactivation of AmLSA due to strong adsorption of poly-substituted benzenes and/or propene oligomers was remarkably depressed by supporting platinum and supplying hydrogen into the propene stream. Consequently, the activity of Pt/AmLSA catalyst had increased almost 1.5 times that of AmLSA. At the same level of benzene conversion, the product distribution f isopropyl-substituted benzenes obtained on Pt/AmLSA was identical to that on AmLSA, and had shifted slightly into the mono-substituted benzene side compared with the result on AmLSA in the absence of hydrogen. In the isopropylation of benzene with 2-chloropropane, the results quite similar to those described above were obtained. From the above observations, synergetic effects of platinum supporting and hydrogen supplying were considered to be due to the presence of hydrogen atoms spilled over from the platinum surface to the strong Lewis acid sites. (author)

  8. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system. (United States)

    Tang, Xuxiang; Liu, Fuqi


    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection.

  9. A proposed role played by benzene itself in the induction of acute cytopenia: inhibition of DNA synthesis. (United States)

    Lee, E W; Garner, C D; Johnson, J T


    A single intraperitoneal dose of benzene (880 mg/kg) in mice inhibited DNA synthesis of bone marrow cells within one hour postinjection. However, there was no inhibitory effect on the synthesis of heme and protein at that dosage. Dose-dependent inhibition of DNA synthesis by benzene was observed over the range of 440 to 1760 mg/kg, supporting the idea that cytopenia which was observed by others following multiple doses of benzene (e.g., 440 or 880 mg/kg) might be due to the inhibitory effect of benzene on DNA synthesis. In our studies, benzene concentrations above 81 micrograms/g wet bone marrow resulted in inhibition of DNA synthesis, regardless of whether it was given ip or by inhalation. The effect of benzene itself, rather than its toxic metabolites, on DNA synthesis was further seen in experiments using a bone marrow cell culture system and cell-free DNA synthetic system. Experimental results demonstrated that benzene alone was capable of inhibiting the DNA synthesis of bone marrow cells and that the reduced DNA synthesis resulted from the inhibitory effect of benzene on DNA polymerase alpha, the enzyme that catalyzes the last step of the DNA synthetic pathway. Thus, benzene itself could play a significant role in inducing myelotoxicity in the case of acute or subacute toxicity by exerting its inhibitory effect on DNA synthesis.

  10. Rotating biological contactor reactor with biofilm promoting mats for treatment of benzene and xylene containing wastewater. (United States)

    Sarayu, K; Sandhya, S


    A novel rotating biological contactor (RBC) bioreactor immobilized with microorganisms was designed to remove volatile organic compounds (VOC), such as benzene and xylene from emissions, and its performance was investigated. Gas-phase VOCs stripped by air injection were 98 % removed in the RBC when the superficial air flow rate was 375 ml/h (1,193 and 1,226 mg/l of benzene and xylene, respectively). The maximum removal rate was observed to be 1,007 and 1,872 mg/m(3)/day for benzene and xylene, respectively. The concentration profile of benzene and xylene along the RBC was dependent on the air flow rate and the degree of microbial adaptation. Air flow rate and residence time were found to be the most important operational parameters for the RBC reactor. By manipulating these operational parameters, the removal efficiency and capacity of the bioreactor could be enhanced. The kinetic constant K (s) demonstrated a linear relationship that indicated the maximum removal of benzene and xylene in RBC reactor. The phylogenic profile shows the presence of bacterium like Pseudomonas sp., Bacillus sp., and Enterococcus sp., which belonged to the phylum Firmicutes, and Proteobacteria that were responsible for the 98 % organic removal in the RBC.

  11. Spatial and Orientational Structure of the Hydration Shell of Benzene in Sub- and Supercritical Water. (United States)

    Choudhary, Ashu; Chandra, Amalendu


    The spatial and orientational structure of the solvation shell of benzene in sub- and supercritical water are investigated by means of molecular dynamics simulations. The present study reveals different local organization of water molecules at different parts of the solute. The π-hydrogen-bonding between benzene and water along the axial direction is found to exist even at supercritical conditions although to a reduced extent. The coordination number of benzene decreases substantially on increase of temperature and decrease of density. While the π-hydrogen-bonded part in the axial region shows a slight expansion, the hydrophobically solvated part in the equatorial plane shows an opposite behavior as the temperature is increased from normal to the supercritical temperature. Two other distribution functions, namely the radial/angular and spatial orientational functions (SOFs) are calculated to explore the spatially resolved angular preferences of water molecules around the benzene solute. Water molecules located axial to the benzene are found to have strong inward orientation toward the solute, however an opposite behavior is found in the equatorial region. Although at supercritical conditions, the orientational distributions of water molecules are broadened, the preferential orientations in the axial and equatorial regions remain similar to that under ambient condition on average.

  12. How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

    KAUST Repository

    Turias, Francesc


    The present computational study complements experimental efforts to describe and characterize carbo-benzene derivatives as paradigms of aromatic carbo-mers. A long-lasting issue has been the possibility of the π-electron crown of the C18 carbo-benzene ring to fit metals or any chemical agents in its core. A systematic screening of candidate inclusion complexes was carried out by density functional theory calculations. Mayer bond order, aromaticity indices, and energy decomposition analyses complete the understanding of the strength of the host-guest interaction. The change in steric and electronic properties induced by the guest agent is investigated by means of steric maps. Substitution of H atoms at the carbo-benzene periphery by electron-withdrawing or electron-donating groups is shown to have a determining influence on the stability of the inclusion complex ions: while electronegative substituents enhance the recognition of cations, electropositive substituents do the same for anions. The results confirm the experimental failure hitherto to evidence a carbo-benzene complex. Nevertheless, the affinity of carbo-benzene for the potassium cation appears promising for the design of planar hydrocarbon analogues of biologic ion carriers. © 2015 Springer Science+Business Media New York.

  13. Concentration dependence of the embryotoxic effects of benzene inhalation in CFY rats. (United States)

    Tátrai, E; Ungváry, G; Hudák, A; Rodics, K; Lörincz, M; Barcza, G


    CFY rats were exposed to continuous benzene inhalation 24 h/day from day 7 to day 14 of gestation at 150, 450, 1500, or 3000 mg/m3 (50, 150, 500, or 1000 ppm) atmospheric concentrations. None of the benzene concentrations used proved to be teratogenic. There was no increase in the incidence of external, visceral, or skeletal malformations. Benzene inhalation at a 150 mg/m3 concentration brought about a slight toxic effect at a 450 mg/m3 concentration a more pronounced effect on both mothers and fetuses. The toxic effects were manifest as an increase in maternal mortality, circulatory damage, decreased gain in body weight, decrease in the weight of the placenta in the mothers and an increase in mortality (early and late), retardation of development (weight and skeleton) in the fetuses. No further change in the parameters was seen with further increases in benzene concentration. Avoidance of the risks of benzene exposure seems desirable before the commencement of planned pregnancy in the human.

  14. Incense, sparklers and cigarettes are significant contributors to indoor benzene and particle levels

    Directory of Open Access Journals (Sweden)

    Werner Tirler


    Full Text Available Introduction. The increased use of incense, magic candles and other flameless products often produces indoor pollutants that may represent a health risk for humans. Today, in fact, incense and air fresheners are used inside homes as well as in public places including stores, shopping malls and places of worship. As a source of indoor contamination, the impact of smoke, incense and sparklers on human health cannot be ignored. Aim. In the present work, we report the results of an emission study regarding particles (PM10 and particle number concentration, PNC and benzene, produced by various incense sticks and sparklers. Results and discussion.The results obtained for benzene, PM10 and PNC, showed a strong negative influence on air quality when these products were used indoors. Various incense sticks gave completely different benzene results: from a small increase of the benzene concentration in the air, just slightly above the background levels of ambient air, to very high concentrations, of more than 200 µg/m³ of benzene in the test room after the incense sticks had been tested.

  15. Detection of Sperm DNA Damage in Workers Exposed to Benzene by Modified Single Cell Gel Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Bo SONG; Zhi-ming CAI; Xin LI; Li-xia DENG; Qiao ZHANG; Lu-kang ZHENG


    Objective To assess the effect of benzene on sperm DNA damageMethods Twenty-seven benzene-exposed workers were selected as exposed groupand 35 normal sperm donors as control group. Air concentration of benzene series inworkshop was determined by gas chromatography. As an internal exposure dose ofbenzene, the concentration of trans, trans-muconic acid (ttMA) was determined byhigh performance liquid chromatography. DNA was detected by modified single cellgel electrophoresis (SCGE).Results The air concentrations of benzene, toluene and xylene at the workplace were86.49 ± 2.83 mg/m3, 97.20 ±3.52 mg/m3 and 97.45 ±2.10 mg/m3, respectively.Urinary ttMA in exposed group (1.040 ± 0.617 mg/L) was significantly higher thanthat of control group (0.819 ± 0.157 mg/L). The percentage of head DNA, determinedby modified SCGE method, significantly decreased in the exposed group (n=13, 70.18%± 7.36%) compared with the control (n=16, 90.62% ± 2.94%)(P<0.001).Conclusion The modified SCGE method can be used to investigate the damage ofsperm DNA. As genotoxin and reprotoxins, benzene had direct effect on the germ cellsduring the spermatogenesiss.

  16. Au/ZnO nanocomposites: Facile fabrication and enhanced photocatalytic activity for degradation of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hang; Ming, Hai; Zhang, Hengchao; Li, Haitao; Pan, Keming [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wang, Fang; Gong, Jingjing [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Kang, Zhenhui, E-mail: [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)


    Au nanoparticles supported on highly uniform one-dimensional ZnO nanowires (Au/ZnO hybrids) have been successfully fabricated through a simple wet chemical method, which were first used for photodegradation of gas-phase benzene. Compared with bare ZnO nanowires, the as-prepared Au/ZnO hybrids were found to possess higher photocatalytic activity for degradation of benzene under UV and visible light (degradation efficiencies reach about 56.0% and 33.7% after 24 h under UV and visible light irradiation, respectively). Depending on excitation happening on ZnO semiconductor or on the surface plasmon band of Au, the efficiency and operating mechanism are different. Under UV light irradiation, Au nanoparticles serve as an electron buffer and ZnO nanowires act as the reactive sites for benzene degradation. When visible light is used as the light irradiation source, Au nanoparticles act as the light harvesters and photocatalytic sites alongside of charge-transfer process, simultaneously. -- Graphical abstract: Under visible light irradiation, Au nanoparticles, which are supported on ZnO nanowires, dominate their catalytic properties in gas-phase degradation benzene reaction. Highlights: Black-Right-Pointing-Pointer The composites that Au nanoparticles supported on ZnO nanowires were synthesized. Black-Right-Pointing-Pointer Au/ZnO composites were firstly used as effective photocatalysts for benzene degradation. Black-Right-Pointing-Pointer Two operating mechanisms were proposed depending on excitation wavelength.

  17. A co-crystal between benzene and ethane: a potential evaporite material for Saturn's moon Titan

    Directory of Open Access Journals (Sweden)

    Helen E. Maynard-Casely


    Full Text Available Using synchrotron X-ray powder diffraction, the structure of a co-crystal between benzene and ethane formed in situ at cryogenic conditions has been determined, and validated using dispersion-corrected density functional theory calculations. The structure comprises a lattice of benzene molecules hosting ethane molecules within channels. Similarity between the intermolecular interactions found in the co-crystal and in pure benzene indicate that the C—H...π network of benzene is maintained in the co-crystal, however, this expands to accommodate the guest ethane molecules. The co-crystal has a 3:1 benzene:ethane stoichiometry and is described in the space group R\\bar 3 with a = 15.977 (1 Å and c = 5.581 (1 Å at 90 K, with a density of 1.067 g cm−3. The conditions under which this co-crystal forms identify it is a potential that forms from evaporation of Saturn's moon Titan's lakes, an evaporite material.

  18. Novel three-stage kinetic model for aqueous benzene adsorption on activated carbon. (United States)

    Choi, Jae-Woo; Choi, Nag-Choul; Lee, Soon-Jae; Kim, Dong-Ju


    We propose a novel kinetic model for adsorption of aqueous benzene onto both granular activated carbon (GAC) and powdered activated carbon (PAC). The model is based on mass conservation of benzene coupled with three-stage adsorption: (1) the first portion for an instantaneous stage or external surface adsorption, (2) the second portion for a gradual stage with rate-limiting intraparticle diffusion, and (3) the third portion for a constant stage in which the aqueous phase no longer interacts with activated carbon. An analytical solution of the kinetic model was validated with the kinetic data obtained from aqueous benzene adsorption onto GAC and PAC in batch experiments with two different solution concentrations (C(0)=300 mg L(-1), 600 mg L(-1)). Experimental results revealed that benzene adsorption for the two concentrations followed three distinct stages for PAC but two stages for GAC. The analytical solution could successfully describe the kinetic adsorption of aqueous benzene in the batch reaction system, showing a fast instantaneous adsorption followed by a slow rate-limiting adsorption and a final long constant adsorption. Use of the two-stage model gave incorrect values of adsorption coefficients in the analytical solution due to inability to describe the third stage.

  19. Monomer and dimer radical cations of benzene, toluene, and naphthalene. (United States)

    Das, Tomi Nath


    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.

  20. An assessment of theoretical methods for nonbonded interactions: comparison to complete basis set limit coupled-cluster potential energy curves for the benzene dimer, the methane dimer, benzene-methane, and benzene-H2S. (United States)

    Sherrill, C David; Takatani, Tait; Hohenstein, Edward G


    Large, correlation-consistent basis sets have been used to very closely approximate the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] complete basis set potential energy curves of several prototype nonbonded complexes, the sandwich, T-shaped, and parallel-displaced benzene dimers, the methane-benzene complex, the H2S-benzene complex, and the methane dimer. These benchmark potential energy curves are used to assess the performance of several methods for nonbonded interactions, including various spin-component-scaled second-order perturbation theory (SCS-MP2) methods, the spin-component-scaled coupled-cluster singles and doubles method (SCS-CCSD), density functional theory empirically corrected for dispersion (DFT-D), and the meta-generalized-gradient approximation functionals M05-2X and M06-2X. These approaches generally provide good results for the test set, with the SCS methods being somewhat more robust. M05-2X underbinds for the test cases considered, while the performances of DFT-D and M06-2X are similar. Density fitting, dual basis, and local correlation approximations all introduce only small errors in the interaction energies but can speed up the computations significantly, particulary when used in combination.

  1. The Effect of Hydration on the Cation-π Interaction Between Benzene and Various Cations

    Indian Academy of Sciences (India)



    The effect of hydration on cation-π interaction in Mq+ BmWn (B = benzene; W = water; Mq+ =Na⁺, K⁺, Mg²⁺, Ca²⁺, Al³⁺, 0 ≤ n,m ≤ 4, 1≤ m + n ≤ 4) complexes has been investigated using ab initio quantum chemical methods. Interaction energy values computed at the MP2 level of theory using the 6-31G(d,p) basis set reveal a qualitative trend in the relative affinity of different cations for benzene and water in these complexes. The π–cloud thickness values for benzene have also been estimated for these systems.

  2. Changes in DNA methylation patterns in subjects exposed to low-dose benzene. (United States)

    Bollati, Valentina; Baccarelli, Andrea; Hou, Lifang; Bonzini, Matteo; Fustinoni, Silvia; Cavallo, Domenico; Byun, Hyang-Min; Jiang, Jiayi; Marinelli, Barbara; Pesatori, Angela C; Bertazzi, Pier A; Yang, Allen S


    Aberrant DNA methylation patterns, including global hypomethylation, gene-specific hypermethylation/hypomethylation, and loss of imprinting (LOI), are common in acute myelogenous leukemia (AML) and other cancer tissues. We investigated for the first time whether such epigenetic changes are induced in healthy subjects by low-level exposure to benzene, a widespread pollutant associated with AML risk. Blood DNA samples and exposure data were obtained from subjects with different levels of benzene exposure, including 78 gas station attendants, 77 traffic police officers, and 58 unexposed referents in Milan, Italy (personal airborne benzene range, 0.20). This is the first human study to link altered DNA methylation, reproducing the aberrant epigenetic patterns found in malignant cells, to low-level carcinogen exposure.

  3. Solubility of toluene, benzene and TCE in high-microbial concentration systems. (United States)

    Barton, John W; Vodraska, Chris D; Flanary, Sandie A; Davison, Brian H


    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(-1) for TCE and 0.25 g mL(-1) for benzene and toluene. The solubility limit increased from 21 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 20mM. For TCE, the solubility increased from 8mM to more than 1000 mM. Solubility for TCE (trichloroethylene) was most heavily impacted by biomass levels, changing by two orders of magnitude as the microbial concentrations approach those in biofilms.

  4. Catalytic Synthesis of Isopropyl Benzene over SO42-/ZrO2 -MCM-41

    Institute of Scientific and Technical Information of China (English)


    Super acid catalyst SO2-4-/ZrO2 was introduced into pure silicone MCM-41 via the impregnation method and the catalyst samples obtained at different temperatures were characterized by means of XRD, IR, and Py-IR techniques.The selectively catalytic gas-phase flow reactions of benzene with propene over the catalyst samples were carried out in a made-to-measure high-pressure flow reactor equipped with a thermostat and a condenser. Effect of the preparative condition on the catalytic synthesis of isopropyl benzene over the catalyst samples was tested. The results show that SO2-4/ZrO2-MCM-41 (SZM-41) can be used as a catalyst for the title reaction, in which there are a higher conversion (97%) for the propene and a higher selectivity(93%) for the isopropyl benzene.


    Institute of Scientific and Technical Information of China (English)

    Gao-fei Xu; Wei-pu Zhu


    P(AA-MA) copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis. These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation. The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail. For the random copolymers, the permeate flux decreased rapidly with the increasing of molecular weight. The separation factor was also influenced by the molecular weight, which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight. Contrarily, the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/(m2h) to 50 wt% benzene/cyclohexane mixture.

  6. Organic chemistry. A rhodium catalyst for single-step styrene production from benzene and ethylene. (United States)

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


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

  7. 4-[(E-(5-tert-Butyl-2-hydroxyphenyldiazenyl]benzoic acid benzene hemisolvate

    Directory of Open Access Journals (Sweden)

    Edward R. T. Tiekink


    Full Text Available The title benzene hemisolvate, C17H18N2O3·0.5C6H6, features an essentially planar (the r.m.s. deviation of the non-H atoms, excluding methyl-C, is 0.071 Å diazo molecule with an E conformation about the N=N bond, and a half-molecule of benzene disposed about a centre of inversion. The dihedral angle formed between the benzene rings of the diazo molecule is 7.69 (12°. In the crystal, centrosymmetrically related dimers associate via the eight-membered carboxylic acid dimer synthon, {...HOC(=O}2, and these are connected into a supramolecular chain along the b axis via C—H...O contacts.

  8. Metabolism of carbon-14-labeled benzene and toluene in avocado fruit

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, E.F.; Olson, A.C.


    The method of exposing avocado fruit to /sup 14/C labeled benzene or toluene was as follows. Fuerte variety avocado fruit was used. It was exposed to the vapor of the hydrocarbons which were circulated in a container. Three mature preclimacteric fruit were used in each experiment. The nonvolatile metabolites from both hydrocarbons were separated into classes of compounds by their solution in water, separation of lipids, and passage of the aqueous solution through ion exchange columns. The results indicate that in avocados the relatively inert hydrocarbons benzene and toluene are metabolized to a series of compounds, toluene to a greater extent than benzene. Both are metabolized to a small but significant extent to CO/sub 2/. 7 references, 2 tables.

  9. Vibrational studies of benzene, pyridine, pyridine-N-oxide and their cations. (United States)

    Kumar, M; Srivastava, Mayuri; Yadav, R A


    IR and Raman spectra of pyridine and pyridine-N-oxide have been recorded and analyzed. The optimized molecular geometries, APT charges and vibrational characteristics for benzene, pyridine, pyridine-N-oxide and their cations have been computed using DFT method. Due to attachment of O atom at N site or removal of electron all the modes are affected in magnitudes. However, significant changes are noticed in their IR intensities, Raman activities and depolarization ratios of the Raman bands in going from pyridine to its N-oxide or in going from neutrals to their cations. It is interesting to note that in going from benzene to benzene cation charge redistribution takes place to reduce the symmetry from D6h to D2h. The calculated frequencies have been correlated with the experimental frequencies for the pyridine and pyridine-N-oxide molecules.

  10. Exposure of hematopoietic stem cells to benzene or 1,4-benzoquinone induces gender-specific gene expression. (United States)

    Faiola, Brenda; Fuller, Elizabeth S; Wong, Victoria A; Pluta, Linda; Abernethy, Diane J; Rose, Jason; Recio, Leslie


    Chronic exposure to benzene results in progressive decline of hematopoietic function and may lead to the onset of various disorders, including aplastic anemia, myelodysplastic syndrome, and leukemia. Damage to macromolecules resulting from benzene metabolites and misrepair of DNA lesions may lead to changes in hematopoietic stem cells (HSCs) that give rise to leukemic clones. We have shown previously that male mice exposed to benzene by inhalation were significantly more susceptible to benzene-induced toxicities than females. Because HSCs are targets for benzene-induced cytotoxicity and genotoxicity, we investigated DNA damage responses in HSC from both genders of 129/SvJ mice after exposure to 1,4-benzoquinone (BQ) in vitro or benzene in vivo. 1,4-BQ is a highly reactive metabolite of benzene that can cause cellular damage by forming protein and DNA adducts and producing reactive oxygen species. HSCs cultured in the presence of 1,4-BQ for 24 hours showed a gender-independent, dose-dependent cytotoxic response. RNA isolated from 1,4-BQ-treated HSCs and HSCs from mice exposed to 100 ppm benzene by inhalation showed altered expression of apoptosis, DNA repair, cell cycle, and growth control genes compared with unexposed HSCs. Rad51, xpc, and mdm-2 transcript levels were increased in male but not female HSCs exposed to 1,4-BQ. Males exposed to benzene exhibited higher mRNA levels for xpc, ku80, ccng, and wig1. These gene expression differences may partially explain the gender disparity in benzene susceptibility. HSC culture systems such as the one used here will be useful for testing the hematotoxicity of various substances, including other benzene metabolites.

  11. Adsorption and diffusion of benzene in the nanoporous catalysts FAU, ZSM-5 and MCM-22: a molecular dynamics study. (United States)

    Rungsirisakun, Ratana; Nanok, Tanin; Probst, Michael; Limtrakul, Jumras


    Molecular dynamics (MD) simulations of benzene in siliceous zeolites (FAU, ZSM-5, and MCM-22) were performed at loadings of 1, 2, 4, 8, and 16 molecules per supercell. The potential energy functions for these simulations were constructed in a semi-empirical way from existing potentials and experimental energetic data. The MD simulations were employed to analyze the dynamic properties of the benzene-zeolite systems. The adsorption energies of benzene/siliceous zeolite complexes increase with increasing loading number, due to the intermolecular attraction between benzene molecules. The self-diffusion coefficient of benzene in siliceous zeolites decreases with increasing loading due to the steric hindrance between the sorbates passing each other. From the zeolite-benzene radial distribution functions it was found that the benzene molecules are relatively far from each other, about 5.2A for siliceous FAU, 5.2A for siliceous ZSM-5, and 4.8A for siliceous MCM-22. In the case of FAU, the benzene molecules prefer to be adsorbed parallel to the surface of the sodalite cage above the six-membered-ring. In ZSM-5, we found a T-structure of the benzene molecules at loadings 2, 4, and 8 molecules per supercell. At loadings of 16 molecules per supercell, the molecules are lined up along the straight channel and their movement is highly correlated. For MCM-22 we found adjacent benzene molecules at a loading of 4 molecules with an orientation similar to the stacked conformation of benzene dimer in the gas phase.

  12. Anaerobic biodegradation of benzene series compounds by mixed cultures based on optional electronic acceptors

    Institute of Scientific and Technical Information of China (English)


    A series of batch experiments were performed using mixed bacterial consortia to investigate biodegradation performance of benzene,toluene,ethylbenzene and three xylene isomers (BTEX) under nitrate,sulfate and ferric iron reducing conditions.The results showed that toluene,ethylbenzeoe,m-xylene and o-xylene could be degraded independently by the mixed cultures coupled to nitrate,sulfate and ferric iron reduction.Under ferric iron reducing conditions the biodegradation of benzene and p-xylene could be occurred only in the presence of other alkylbenzenes.Alkylbenzenes can serve as the primary substrates to stimulate the transformation of benzene and p-xylene under anaerobic conditions.Benzene and p-xylene are more toxic than toluene and ethylbenzene,under the three terminal electron acceptors conditions,the degradation rates decreased with toluene > ethylbenzene > m-xylene > o-xylene > benzene > p-xylene.Nitrate was a more favorable electron acceptor compared to sulfate and ferric iron.The ratio between sulfate consumed and the loss of benzene,toluene,ethylbenzene,o-xylene,m-xylene,p-xylene was 4.44,4.51,4.42,4.32,4.37 and 4.23,respectively;the ratio between nitrate consumed and the loss of these substrates was 7.53,6.24,6.49,7.28,7.81,7.61,respectively;the ratio between the consumption of ferric iron and the loss of toluene,ethylbenzene,o-xylene,m-xylenewas 17.99,18.04,18.07,17.97,respectively.

  13. Qualitative evaluations of benzene in terminals and pipelines; Avaliacoes qualitativas de benzeno em terminais e oleodutos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Edson Ferreira da; Baltar, Joao Luiz da Conceicao [TRANSPETRO - PETROBRAS Transportes, Rio de Janeiro, RJ (Brazil)


    The benzene (C6H6) is a stable hydrocarbon, with pleasant smell, plenty toxic, being able to injure sanguine cells and to cause cancer. It is used as raw materials in the obtainment of several products (inks, waxes, lubricants, etc.), chemicals intermediate and, also, it is found in the petrochemical naphtha and in the gasoline. About 80% of the contaminations for benzene are attributed to the gasoline. In relation to the benzene contents present in the petrochemical processes produced in Brazil, the recent Portaria Interministerial no. 775 (Brazil,2004), of April 28, 2004, prohibits, in whole national territory, the commercialization of finished products that contain benzene in its composition. It is admitted, even so, the presence of this substance as contaminant agent in percentage non superior at 0,8% (in volume), from July 1st, 2004, 0,4% (in volume), from 1st of December of 2005 and 0,1% (in volume), from December 1st, 2007. The Brazilian Ministry of Labour regulation NR-15, P. 776, establish that the companies that produce, transport, store, use or manipulate benzene and its liquid mixtures contends 1% or more of volume, accomplish the registration in the SST - MTE and initiation the Programa de Prevencao de Exposicao Ocupacional ao Benzeno - PPEOB in TRANSPETRO. During the evaluations they had been carried through the recognition of the places, equipment and they had defined the homogeneous groups of exhibition - GHE. From these information, environmental and biological evaluations in the terminals and intermediary stations (TECAM, TEVOL, ESTAP, ESMAN, ESVOL and ESJAP), had been executed, including the accomplishment of essays to determine the presence of benzene in the liquid phase, through the infrared base equipment, GS 1000. With base in the results mitigation and remediation actions were implemented in order to guarantee the occupational health of the components of GHE. (author)

  14. Alkylation mechanism of benzene with 1-dodecene catalyzed by Et3NHCl-AlCl3

    Institute of Scientific and Technical Information of China (English)


    The isotope exchange method was employed to investigate the catalytic mechanism of ionic liquid in alkylation of benzenes with olefins.It is proposed that alkylation was induced by the Lewis acid AlCl3 which attracted π electrons of 1-dodecene to shift toward 1-carbon,thus forming a carbonium ion.The carbonium ion further reacted with benzenes to form a complex.Due to unstabilit of the complex,a deuterated ring proton was transferred into an electronegative 1-carbon of the side chain to substitute for the AlCl3,accordingly 2-phenyldodecane was generated.

  15. RPBE-vdW Description of Benzene Adsorption on Au(111)

    DEFF Research Database (Denmark)

    Pedersen, Jess Wellendorff; Kelkkanen, Kari André; Mortensen, Jens Jørgen


    Density functional theory has become a popular methodology for the analysis of molecular adsorption on surfaces. Despite this popularity, there exist adsorption systems for which commonly used exchange-correlation functionals fail miserably. Particularly those systems where binding is due to van...... der Waals interactions. The adsorption of benzene on Au(111) is an often mentioned such system where standard density functionals predict a very weak adsorption or even a repulsion, whereas a significant adsorption is observed experimentally. We show that a considerable improvement in the description...... of the adsorption of benzene on Au(111) is obtained when using the so-called RPBE-vdW functional....

  16. Photocatalytic Oxidation of Gaseous Benzene under 185 nm UV Irradiation


    Haibao Huang; Xinguo Ye; Huiling Huang; Peng Hu; Lu Zhang; Leung, Dennis Y. C.


    Benzene is a toxic air pollutant and causes great harm to human being. Photocatalytic oxidation (PCO) has been frequently studied for benzene removal, however, its PCO efficiency is still very low and the photocatalysts are easy to be deactivated. To improve the efficiency and stability of PCO, UV lamps with partial 185 nm UV irradiation were used to activate photocatalysts (denoted as 185-PCO). Cobalt modified TiO2 (Co-TiO2) was developed to improve the PCO activity and eliminate ozone gener...

  17. Oxides Catalysts of Rare Earth and Transient Metal for Catalytic Oxidation of Benzene

    Institute of Scientific and Technical Information of China (English)

    Liang Kun; Li Rong; Chen Jianjun; Ma Jiantai


    The catalysts of CeO2 and the mixture of CeO2 and CuO were prepared, and the activities of these catalysts for completely oxidizing benzene were studied.The results show that the optimal proportion of CeO2/CuO is 6: 4.The highest temperature at which benzene was completely oxidized on these catalysts at different airspeed was measured.Compared these catalysts with the noble metal used, our catalysts had superiority in the resources and the industrial cost besides good activities.

  18. Hydrodynamic influences of tidal fluctuations and beach slopes on benzene transport in unconfined, sandy costal aquifers (United States)

    Ni, C.-F.; Wei, Y.-M.


    Oil spills in oceans have led to severe environment and ecosystem problems due to high toxicity substances, large spatial extents, and long temporal durations. The BTEX compounds are key indexes generally used for identifications of such contamination events and also for quantifications of residual substances after remediations. Benzene is one of the BTEX compounds, which is recognized to be high toxicity and may threat near-shore ecosystem and human safety. Therefore, the understanding of benzene transport in costal aquifers is critical for predictions of contaminated zones and managements and organizations of remediation plans. In this study a numerical investigation was conducted to quantify the influence of tidal fluctuations and beach slopes on benzene transport in an unconfined coastal aquifer. More specifically, three different tidal amplitudes and three beach slopes were considered in the two-dimensional HYDROGEOCHEM model to characterize the spatial and temporal behavior of the benzene transport. Simulation results show that tidal fluctuations will lead to shallow seawater circulations near the ground surface where the high tides can reach periodically. Such local circulation flows will trap benzene plume and the plume may migrate to the deeper aquifer, depending on the amplitudes of tides and the surface slopes of the coastal lines. The sine curve tides with 0.5 m amplitudes will create circulation plume sizes of about 50m in length and 20m in depth, while the circulation plume sizes for tides with 1.0 m amplitudes will significantly increase to approximately 150 m in length and 60 m in depth. Additionally, double the beach slopes and keep the same tidal amplitude will lead to 40 m plume movement toward the land. The amplitude of tidal fluctuation is the key factor to decide when and where a benzene plume reaches a largest depth. In general, the plume with tidal amplitude of 0.5 m requires 50 days to reach 90% of the largest depth. However, the plume with

  19. Advances in Study on Catalysts for Phenol Synthesis via Catalytic Hydroxylation of Benzene in China

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhaohui


    Synthesis of phenol via direct hydroxylation of benzene as a typical reaction of atomic economy has attracted extensive attention worldwide and has also become an actively investigated domain in China. This article refers to the recent domestic advances in study on phenol synthesis via hydroxylation of benzene from the viewpoint of catalysts, and considers the TS-1/H2O2 and FeZSM-5/N2O catalytic systems to be promising ones with good prospects for commercialization along with some suggestions on future research work.

  20. Reactions of the radical cations of methylated benzene derivatives in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Sehested, K.; Holcman, J.


    The radical cations of methylated benzene decompose in acid solution into the corresponding methylbenzyl radical and a proton. The rate constant for this reaction decreases by three orders of magnitude as the number of methyl groups increases from one to five. The rate constants can be correlated with the ionization potential of the parent compound. In neutral solution the reverse reaction to the acid-catalyzed OH adduct conversion occurs and the radical cations react with water to form the OH adduct. In slightly alkaline solution the radical cations of the higher methylated benzenes (n greater than or equal to 3) react with hydroxide ions forming the OH adduct.

  1. Spin-polarization reversal at the interface between benzene and Fe(100)

    KAUST Repository

    Goumri-Said, Souraya


    The spin-polarization at the interface between Fe(100) and a benzene is investigated theoretically using density functional theory for two positions of the organic molecule: planar and perpendicular with respect to the substrate. The electronic and magnetic properties as well as the spin-polarization close to the Fermi level strongly depend on the benzene position on the iron surface. An inversion of the spin-polarization is induced by p-d hybridization and charge transfer from the iron to the carbon sites in both configurations.

  2. Ultrafast Photophysics of Star-Like Molecules with Benzene and Triazine Core

    Institute of Scientific and Technical Information of China (English)

    FENG Wen-Ke; KONG sheng; XIAO Li-Xin; MENG Kang; WANG Shu-Feng; GONG Qi-Huang


    Static and transient spectroscopic characters of newly synthesized start-like molecules,1,3,5-tri(10-butyl-3-propenyl-10H-phenothiazine)-benzene(TP3B)and 2,4,6-tri(10-butyl-3-propenyl-10H-phenothiazine)-[1,3,5]triazine(TP3T),are studied using static,picosecond fluorescence and femtosecond transient absorption spectroscopy.The results show that when the benzene group is in the center,a large conjugation system is formed,while a fast electron transfer process happens when the center group is triazine.

  3. Fullerene-Benzene purple and yellow clusters: Theoretical and experimental studies (United States)

    Lundgren, Megan P.; Khan, Sakiba; Baytak, Aysegul K.; Khan, Arshad


    Fullerene (FR, C60) gives a purple colored solution almost instantly when benzene is added to it. Interestingly, this purple solution turns yellow in about 7 weeks and remains yellow afterwards. The concentration of the purple complex increases with temperature indicating its formation kinetically favored, which transforms into a more stable yellow complex very slowly with time. The geometry optimization by density functional theory (DFT) followed by spectra (TD-DFT method) calculations suggest that the purple and yellow complexes are due to clusters of six benzene molecules arranged vertically and horizontally respectively around the FR molecule.

  4. Effect of laser radiation on reparative processes in the hemogenic system of rabbits after benzene poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Sarkisyan, A.P.; Teodorovich, B.P.


    Benzene was administered to 30 rabbits at a rate of 0.37 ml per kg of body weight on a daily basis, with the general dosage ranging from 8.12 to 21.3 ml. Doses were continued until the appearance of persistent leucopenia. Then a complete blood picture was prepared and histological material collected and evaluated. Of 18 rabbits who survived the benzene poisoning, 9 were treated with a helium-neon laser and the others used as controls. Results indicated that the laser treatment accelerated the regeneration of blood cells, particularly of the red part of hemogenic tissue. 11 references, 1 figure.

  5. catena-Poly[[aqua(imidazolecadmium(II]-μ3-benzene-1,3-dicarboxylato

    Directory of Open Access Journals (Sweden)

    Zhengfang Zeng


    Full Text Available In the title compound, [Cd(C8H4O4(C3H4N2(H2O]n, the CdII ion is seven-coordinated by five O atoms from three crystallographically independent benzene-1,3-carboxylate ligands, one N atom from the imidazole ligand and one coordinated water molecule. Neighboring CdII ions are bridged by the benzene-1,3-dicarboxylate ligands, forming a zigzag polymeric chain structure. These chains are further extended into a three-dimensional supramolecular structure through O—H...O and N—H...O hydrogen bonds.

  6. The relationship between distillation range of crude benzene and the content of three benzene%粗苯馏程与三苯含量的关系

    Institute of Scientific and Technical Information of China (English)



    In this paper, comparison analysis and function simulation on the coking plant chemical products quality index of the amount of distilling crude benzene before 180 ℃ as the products quality index and its benzene, toluene, xylene components of the sum of the detected data content for the coking plant were carried out. It was found that there was a linear relation between the distillation range of crude benzene and its content. And this model had some practical value and guiding significane for analysis, detection and real process production.%对焦化厂化工产品粗苯的质量指标180℃前馏出量与其苯、甲苯、二甲苯组分的含量之和的测定数据进行了对比分析和函数模拟,结果表明,两者之间存在着线性关系,且所得的一元线性回归方程对分析检测和工艺生产有着实际的指导意义。

  7. Conformational instability of the lowest triplet state of the benzene nucleus: II. p-Xylene, the influence of substituents

    NARCIS (Netherlands)

    J.H. van der Waals; M.C. van Hemert; W.J. Buma


    A calculation of the potential-energy surface of the lowest triplet state of p-xylene as a function of the S8(,) distortion coordinate of the benzene skeleton has been made to learn more about the influence of substituents on the vibronically induced distortion of benzene in its metastable triplet s

  8. Differentiation of HL-60 promyelocytes to granulocytes induced via the activation of protein kinase-C by benzene

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.; O' Connor, A.; Kalf, G. (Rutgers-the State Univ., Piscataway, NJ (United States) Thomas Jefferson Univ., Philadelphia, PA (United States))


    Benzene is a hematotoxin which affects the development of bone marrow progenitor cells and a leukemogen which causes acute myelogenous leukemia. The authors studied the effect of benzene on the differentiation of progenitors of the myeloid lineage, using HL-60 promyelocytic leukemia cells which can be induced to differentiate to granulocytes via the activation of protein kinase-C (PKC) by DMSO and retinoic acid. Exposure of HL-60 cells to 5 mM benzene for 5 min. results in the activation of PKC as measured by an increases in the phosphorylation of cellular proteins in a whole cell assay including proteins pp17 and pp27 reported by Feuerstein and Cooper to be involved in HL-60 cell differentiation. The increase in protein phosphorylation observed with benzene was equally as great as that observed with 100 ng/mL PMA, used as a control. Under the same conditions, benzene induces differentiation of the promyelocytes into granulocytes as measured by the acquisition of superoxide production and granulocyte morphology. Preincubation with 40 {mu}M sphinganine, a PKC inhibitor, prevents the benzene-induced increase in cellular protein phosphorylation and the differentiation to granulocytes. These results indicate that benzene, by activation of PKC, can affect myeloid differentiation which may play a role in the ability of benzene to cause acute myelogenous leukemia.

  9. Solubilities of benzene, toluene and diphenyl in the t-butyl alcohol + water mixtures and hydrophobic interaction

    Institute of Scientific and Technical Information of China (English)

    邹立壮; 杨冠英; 韩布兴; 刘瑞麟; 阎海科


    The solubilitices of benzene, toluene and diphenyl in mixed solvents of t-butyl alcohol (TBA) and water at 283.15, 288.15, 293.15 and 298.15 K have been determined by spectrophotometry. The mole fraction of TBA [x (TBA)] in the mixed solvent are 0.000, 0.010, 0.020, 0.030, 0.040, 0.045, 0.050, 0.060, 0.080 and 0.100, respectively. The standard Gibbs energies of solution of benzene, toluene and diphenyl in the mixed solvent have also been calculated based on the solubility data. The hydrophobic interactions (HI) for the pairs of benzene-benzene, methane-benzene and methane-methane in the mixed solvent were calculated and discussed.

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

    Directory of Open Access Journals (Sweden)

    Kheirbek Iyad


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

  11. The Self-Assembly Properties of a Benzene-1,3,5-tricarboxamide Derivative (United States)

    Stals, Patrick J. M.; Haveman, Jan F.; Palmans, Anja R. A.; Schenning, Albertus P. H. J.


    A series of experiments involving the synthesis and characterization of a benzene-1,3,5-tricarboxamide derivative and its self-assembly properties are reported. These laboratory experiments combine organic synthesis, self-assembly, and physical characterization and are designed for upper-level undergraduate students to introduce the topic of…

  12. Photocatalytic Oxidation of Gaseous Benzene under 185 nm UV Irradiation

    Directory of Open Access Journals (Sweden)

    Haibao Huang


    Full Text Available Benzene is a toxic air pollutant and causes great harm to human being. Photocatalytic oxidation (PCO has been frequently studied for benzene removal, however, its PCO efficiency is still very low and the photocatalysts are easy to be deactivated. To improve the efficiency and stability of PCO, UV lamps with partial 185 nm UV irradiation were used to activate photocatalysts (denoted as 185-PCO. Cobalt modified TiO2 (Co-TiO2 was developed to improve the PCO activity and eliminate ozone generated from 185 nm UV irradiation. Results show that benzene removal efficiency of PCO with 254 nm UV irradiation (denoted as 254-PCO is only 2.1% while it was greatly increased to 51.5% in 185-PCO. 185-PCO exhibited superior capacity for benzene oxidation. In the 185-PCO process, much ozone was left in case of TiO2 as photocatalysts while it can be nearly eliminated by 1% Co-TiO2.

  13. Novel Carbon Nanotubes-supported NiB Amorphors Alloy Catalyst for Benzene Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mei Hua YANG; Rong Bin ZHANG; Feng Yi LI


    The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina.

  14. The Retention Behaviors of Benzene and Its Alkyl Homologues in Microemulsion Electrokinetic Chromatography

    Institute of Scientific and Technical Information of China (English)


    The retention behaviors of benzene and its alkyl homologues in microemulsion electrokinetic chromatography were investigated in both anionic and cationic surfactant MEEKC systems. The effects of the composition of microemulsion on retention time and selectivity were studied. A good linear relationship was obtained between log k' and the carbon number of alkyl chain.

  15. Quantitative structure-activity relationships for the Toxicity of Substituted Benzenes to Cyprinus carpio

    Institute of Scientific and Technical Information of China (English)



    Objective To measure the 96h-LC50 values of 32 substituted benzenes to the carp and to study the relationship between quantitative structure-activity and structural parameters of chemicals. Methods The acute toxicity values of 32 substituted benzenes to the carp were determined in a semistatic test. The energy of the lowest unoccupied molecular orbital, and the highest occupied molecular orbital, the dipole moment and the molecular weight of substituted benzenes were calculated by the quantum chemical method MOPAC6.0. Results The range of the toxicity of studied compounds was broad, and the most toxic compound was pentachlorophenol, while the least toxic compound was 4-methylaniline. By the stepwise regression analyses, a series of Quantitative structure-activity relationships (QSAR) equations were derived from all compounds and subclasses. The equation log1/LC50=0.759logP +2.222 (R2 (adj)=0.818) was found to fit well and the average predicted percentage error was 6.16%. Conclusion The toxicity of anilines and phenols to the carp could be modeled well by logP alone, whereas the toxicity of the halogenated benzenes and nitrobenznes not containing hydroxyl or amino group can be controlled by hydrophobic and electronic factors.

  16. Biomonitoring of benzene and 1,3-butadiene exposure and early biological effects in traffic policemen. (United States)

    Arayasiri, Manaswee; Mahidol, Chulabhorn; Navasumrit, Panida; Autrup, Herman; Ruchirawat, Mathuros


    The objective of this study was to determine benzene and 1,3-butadiene exposure through ambient air and personal air monitoring, as well as through biomarkers of exposure, and to evaluate the potential health risk of exposure through the use of biomarkers of early biological effects in central Bangkok traffic policemen. Ambient air concentrations of benzene and 1,3-butadiene at the roadsides were significantly higher than in police offices used as control sites (pbutadiene (median 3.08 microg/m(3)) than office policemen (median 6.17 microg/m(3) for benzene and 0.37 microg/m(3) for 1,3-butadiene) (pbutadiene metabolite, monohydroxy-butenyl mercapturic acid. Biomarkers of early biological effects, 8-hydroxy-2'-deoxyguanosine in leukocytes (8-OHdG), DNA-strand breaks, and DNA-repair capacity, measured as an increase in gamma ray-induced chromosome aberrations were significantly higher in traffic policemen than controls (pbutadiene exposure were significantly associated with 8-OHdG and olive tail moment at pbutadiene on DNA damage. These results indicated that traffic policemen, who are exposed to benzene and 1,3-butadiene at the roadside in central Bangkok, are potentially at a higher risk for development of diseases such as cancer than office policemen.

  17. Reaction Kinetics of Ozonation of Trichloroethylene and Benzene in Gas and Liquid Phases

    Institute of Scientific and Technical Information of China (English)

    钟理; KuoChiane-Hai


    The kinetics of ozonation reactions of trichloroethylene (TCE) and benzene in gas and liquid phases at 101.3 kPa and 298 K was investigated in this paper. The ozonation of TCE is first order with respect to the ozone concentration and one and half order to TCE in the gas phase with the average rate constant 57.30 (mol·L-1 )-l.5·s-1,and the TCE ozonation in aqueous medium is first order with respect to both ozone and trichloroethylene with the average rate constant 6.30 (mol·L-1)-l·s-1. The ozonation of benzene in the gas phase is first order in ozone but independent of the benzene concentration with the average reaction rate constant 0.0011s-1. The overall kinetics of reaction between ozone and benzene in aqueous solution is found to be first order with one-half order in both ozone and bezene, with the average reaction rate constant 2.67s-1. It is found that the ozonation rate of pallutants is much quicker than that of self-decomposition of ozone in both gas and aqueous phase.

  18. Specific ion effects on the hydrophobic interaction of benzene self-assembled monolayers

    DEFF Research Database (Denmark)

    Dobberschütz, Sören; Pedersen, Morten Rimmen; Hassenkam, Tue;


    interaction of benzene self-assembled monolayers. Using the jump to contact phenomenon of an atomic force microscope (AFM) tip as an indicator of attractive forces between the surfaces of a sample and the tip, we discovered lower frequencies in the snap in as well as narrower distributions for the snap...

  19. 3-Phenyl-1-(p-tolyl-1H-benzo[f]chromene benzene hemisolvate

    Directory of Open Access Journals (Sweden)

    Meng Wei Xue


    Full Text Available The title compound, C26H20O·0.5C6H6, was obtained from condensation reaction of 2-naphthol, 4-methylbenzaldehyde and phenylmethanamine. The naphthyl ring system is orented at dihedral angles of 84.11 (1 and 19.33 (8° with respect to the mean planes of the two benzene rings.

  20. Ethyl benzene-induced ototoxicity in rats : a dose-dependent mild-frequency hearing loss

    NARCIS (Netherlands)

    Cappaert, N.L.M.; Klis, S.F.L.; Baretta, A.B.; Muijser, H.; Smoorenburg, G.F.


    Rats were exposed to ethyl benzene at 0, 300, 400 and 550 ppm for 8 hours/day for 5 consecutive days. Three to six weeks after the exposure, auditory function was tested by measuring compound action potentials (CAP) in the frequency range of 1-24 kHz and 2f1-f2 distortion product otoacoustic emissio

  1. 78 FR 25476 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Benzene... (United States)


    ... exposure to benzene in the workplace does not harm workers. This information collection is subject to the... provisions of law, no person shall generally be subject to penalty for failing to comply with a collection of... information, see the related notice published in the Federal Register on February 28, 2013 (78 FR...

  2. Fifth-order Raman spectroscopy of liquid benzene : Experiment and theory

    NARCIS (Netherlands)

    Milne, C. J.; Li, Y. L.; Jansen, T. L. C.; Huang, L.; Miller, R. J. D.


    The heterodyned fifth-order Raman response of liquid benzene has been measured and characterized by exploiting the passive-phase stabilization of diffractive optics. This result builds on our previous work with liquid carbon disulfide and extends the spectroscopy to a new liquid for the first time.

  3. 46 CFR Appendix C to Subpart C to... - Medical Surveillance Guidelines for Benzene (United States)


    ... benzene immediately causes pulmonary edema and hemorrhage of pulmonary tissue. There is some absorption... must be sought out in the occupational history. IV. Treatment of Acute Toxic Effects Remove from... technology and innovative regimes are making consistent surveillance for leukemia, as well as...

  4. Modulation of Affinity of a Marine Pseudomonad for Toluene and Benzene by Hydrocarbon Exposure (United States)

    Law, A. T.; Button, D. K.


    Trace (microgram liter−1) quantities of either toluene or benzene injected into an amino-acid-limited continuous culture of Pseudomonas sp. strain T2 were utilized immediately with affinities of 2.6 and 6.8 liters g of cells−1 h−1, respectively, and yielded large amounts of organic products, carbon dioxide, and cells. The immediate utilization of hydrocarbons by hydrocarbon-deprived organisms helps to establish the nutritional value of nonpolar substrates in the environment. The observation of small Michaelis constants for toluene transport led to tests of metabolic competition between hydrocarbons; however, competitive inhibition of toluene metabolism was not found for benzene, naphthalene, xylene, dodecane, or amino acids. Benzene and terpenes were inhibitory at milligram liter−1 concentrations. Toluene was metabolized by a strongly inducible system when compared with benzene. The capacity of toluene to effect larger affinity values increased with exposure time and concentration. The kinetics of induction suggested saturation phenomena, resulting in an induction constant, Kind, of 96 μg of toluene liter−1. Maximal induction of amino-acid-grown cells required about 80 h, with the affinity reaching 317 liters g of cells−1 h−1. PMID:16347006

  5. 40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic). (United States)


    ... with substituted phenol (generic). 721.1580 Section 721.1580 Protection of Environment ENVIRONMENTAL... substituted phenol (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as disubstituted benzene ether, polymer with substituted...

  6. A π-electron deficient diaminotriazine functionalized MOF for selective sorption of benzene over cyclohexane

    NARCIS (Netherlands)

    Manna, B.; Mukherjee, S.; Desai, A.V.; Sharma, S.; Krishna, R.; Ghosh, S.K.


    A diaminotriazine functionalized novel MOF (DAT-MOF-1) has been synthesized stemming out of a π-electron-deficient pore-surface functionalization based linker-design principle, which results in efficient selectivity of benzene sorption over its aliphatic analogue cyclohexane, crucial from the indust

  7. Conformational instability of the lowest triplet state of the benzene nucleus: I. The unsubstituted molecule

    NARCIS (Netherlands)

    J.H. van der Waals; M.C. van Hemert; W.J. Buma


    Experiments on benzene have established that its lowest triplet state (3B1u) is conformationally unstable owing to vibronic coupling with the next higher state (3E1u). This instability was found to be critically dependent on the influence of a crystal field. An analogous vibronic coupling is to be e

  8. Combined carbon and hydrogen isotope fractionation investigations for elucidating benzene biodegradation pathways

    NARCIS (Netherlands)

    Fischer, A.; Herklotz, I.; Herrmann, S.; Thullner, M.; Weelink, S.A.B.; Stams, A.J.M.; Richnow, H.H.; Vogt, C.


    Recently, combined carbon and hydrogen isotope fractionation investigations have emerged as a powerful tool for the characterization of reaction mechanisms relevant for the removal of organic pollutants. Here, we applied this approach in order to differentiate benzene biodegradation pathways under o

  9. Human monitoring of exposure to organic solvents. I Benzene, phenol, toluene, cresols and xylenes

    NARCIS (Netherlands)

    Jansen EHJM; de Fluiter P; TOX


    In this report the conclusions of a literature study has been summarized concerning the monitoring of the general population to exposure to benzene-like solvents. Since the Dutch population is exposed to concentrations far below the ppm level, the conclusions on the suitability of biomarkers are ba

  10. 46 CFR Appendix B to Subpart C to... - Substance Technical Guidelines, Benzene (United States)


    .... (8) Appearance and odor: Clear, colorless liquid with a distinctive sweet odor. II. Fire, Explosion... fire-exposed containers cool. (6) Unusual fire and explosion hazards: Benzene is a flammable liquid... engineering). (b) Reactivity. (1) Conditions contributing to instability: Heat. (2) Incompatibility: Heat...

  11. QSARS for Acute Toxicity of Halogenated Benzenes to Bacteria in Natural Waters

    Institute of Scientific and Technical Information of China (English)



    Objective To measure the acute toxicity of halogenated benzenes to bacteria in natural waters and to study quantitative relationships between the structure and activity of chemicals. Methods The concentration values causing 50% inhibition of bacteria growth (24h-IC50) were determined according to the bacterial growth inhibition test method. The energy of the lowest unoccupied molecular orbital and the net charge of carbon atom of 20 halogenated benzenes were calculated by the quantum chemical MOPAC program. Results The log1/IC50 values ranged from 4.79 for 2,4-dinitrochlorobenzene to 3.65 for chlorobenzene. A quantitative structure-activity relationship model was derived from the toxicity and structural parameters: log1/IC50 =-0.531(ELUMO)+1.693(Qc)+0.163(logP)+3.375. This equation was found to fit well (r2=0.860, s=0.106), and the average percentage error was only 1.98%. Conclusion Halogenated benzenes and alkyl halogenated benzenes are non-polar narcotics, and have hydrophobicity-dependent toxicity. The halogenated phenols and anilines exhibit a higher toxic potency than their hydrophobicity, whereas 2,4-dinitrochlorobenzene is electrophile with the halogen acting as the leaving group.

  12. Toluene and benzene inhalation influences on ventricular arrhythmias in the rat. (United States)

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


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

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

    NARCIS (Netherlands)

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


    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

  14. N-(4-Hydroxy­phen­yl)benzene­sulfon­amide


    Khan, Islam Ullah; Mariam, Irfana; Zia-ur-Rehman, Muhammad; Arif Sajjad, Muhammad; Sharif, Shahzad


    The title compound, C12H11NO3S, synthesized by the reaction of benzene sulfonyl chloride with para-amino­phenol, is of inter­est as a precursor to biologically active sulfur-containing heterocyclic compounds. The structure is stabilized by N—H⋯O and O—H⋯O hydrogen bonds.

  15. Laser-Ionization TOF Mass Spectrometer Characterization of Benzene Destruction in Atmospheric Pressure Pulsed Discharge

    Institute of Scientific and Technical Information of China (English)

    LIU Jiahong; XIAO Qingmei; WANG Liping; YAO Zhi; DING Hongbin


    Benzene is.a major industrial air pollutant and can cause serious human health disorders. In this paper an investigation on benzene destruction, in an atmospheric-pressure fast-flow pulsed DC-discharge by means of laser ionization combined with time-of-flight (TOF) mass spectrometry, is reported. Most by-products including transient reactive species from the benzene discharge were characterized by molecular beam sampling combined with TOF mass spectrometry.It is showed that, with a gas mixture of 0.5% C6H6 in Ar, benzene can be effectively destroyed by discharge plasma. The intermediate species consisted of small fragments of CNHm (n=3~5,m =1~11), cycle-chain species of CNHm (n=6~9, m = 7~10) and polycyclic species CNHm (n ≥9,m = 8~12). The alternation of mass peaks (intensity) with even/odd electrons was observed in the measured mass spectra. The results indicated that the alternation is mainly due to the different ionization potentials of the open shell and close shell species. Based on the examination of the features of the species' composition, the primary reaction pathways are proposed and discussed.

  16. Molecular dynamics simulation of benzene-propene-cumene mixtures in different phases. (United States)

    Yang, Xiaofeng; Qin, Zhangfeng; Wang, Guofu; Wang, Jianguo


    Molecular dynamics simulations have been performed to study the microscopic configuration and dynamic behavior of mixtures of benzene, propene, and cumene for the cumene synthesis process. The comparisons have been made for the intermolecular radial distribution functions of the binary and ternary mixtures at the conditions that are near, below, and above their respective critical points. The results have shown that in both binary and ternary mixtures propene molecules have a small tendency to cluster in the liquid state, but at supercritical conditions they tend to be uniformly distributed. Contrary to propene, cumene molecules have a tendency to cluster in ternary mixtures. A moderate local density augmentation is also found in the benzene-propene binary supercritical fluid. The excess functions for benzene-propene binary mixtures have shown that there exists an enhancement of the potential energy when benzene mixes with propene. This enhancement provides a rational explanation for the experimental critical properties, which exhibit the behavior of the nonmonotonous dependence of critical pressure on compositions.


    Ethanol is commonly used as a fuel oxygenate in California and in the mid continent area around the Great Lakes. The presence of ethanol in a gasoline spill has raised concerns about the effects of the additive on the natural biodegradation of fuel hydrocarbons, including benzen...

  18. Gold Catalysts on Y-Doped Ceria Supports for Complete Benzene Oxidation

    Directory of Open Access Journals (Sweden)

    Lyuba Ilieva


    Full Text Available Gold (3 wt. % catalysts on Y-doped (1, 2.5, 5 and 7.5 wt. % Y2O3 ceria supports prepared by coprecipitation (CP or impregnation (IM were studied in complete benzene oxidation (CBO. A low-extent Y modification was chosen to avoid ordering of oxygen vacancies. The samples were characterized by XRD, TGA, XPS and TPR techniques. A positive role of air pretreatment at 350 °C as compared to 200 °C was established for all Y-containing catalysts and it was explained by cleaning the active sites from carbonates. The oxygen supply cannot be considered as a limiting step for benzene oxidation except for the high 7.5%-doped samples, as suggested by TGA and TPR data. On the basis of XPS results of fresh and used in CBO catalysts, the presence of cationic gold species does not seem important for high CBO activity. The gold catalyst on an IM support with 1% Y-doping exhibited the best performance. A 100% benzene conversion was achieved only over this catalyst and Au/ceria, while it was not reached even at 300 °C over all other studied catalysts. Gold and ceria particle agglomeration or coke formation should be excluded as a possible reason, and the most probable explanation could be associated with the importance of the benzene activation stage.

  19. Spectroscopic benzene detection using a broadband monolithic DFB-QCL array (United States)

    Lewicki, Rafał; Witinski, Mark; Li, Biao; Wysocki, Gerard


    Quantitative laser spectroscopic measurements of complex molecules that have a broad absorption spectra require broadly tunable laser sources operating preferably in the mid-infrared molecular fingerprint region. In this paper a novel broadband mid-infrared laser source comprising of an array of single-mode distributed feedback quantum cascade lasers was used to target a broadband absorption feature of benzene (C6H6), a toxic and carcinogenic atmospheric pollutant. The DFB-QCL array is a monolithic semiconductor device with no opto-mechanical components, which eliminates issues with mechanical vibrations. The DFB-QCLs array used in this work provides spectral coverage from 1022.5 cm-1 to 1053.3 cm-1, which is sufficient to access the absorption feature of benzene at 1038 cm-1 (9.64 μm). A sensor prototype based on a 76 m multipass cell (AMAC-76LW, Aerodyne Research) and a dispersive DFB-QCL array beam combiner was developed and tested. The Allan deviation analysis of the retrieved benzene concentration data yields a short-term precision of 100 ppbv/Hz1/2 and a minimum detectable concentration of 12 ppbv for 200 s averaging time. The system was also tested by sampling atmospheric air as well as vapors of different chemical products that contained traces of benzene.

  20. Desorption kinetics of benzene in a sandy soil in the presence of powdered activated carbon. (United States)

    Choi, J-W; Kim, S-B; Kim, D-J


    Desorption kinetics of benzene was investigated with a modified biphasic desorption model in a sandy soil with five different powdered activated carbon (PAC) contents (0, 1, 2, 5, 10% w/w) as sorbents. Sorption experiments followed by series dilution desorption were conducted for each sorbent. Desorption of benzene was successively performed at two stages using deionized water and hexane. Modeling was performed on both desorption isotherm and desorption rate for water-induced desorption to elucidate the presence of sorption-desorption hysteresis and biphasic desorption and if present to quantify the desorption-resistant fraction (q (irr)) and labile fraction (F) of desorption site responsible for rapid process. Desorption isotherms revealed that sorption-desorption exhibited a severe hysteresis with a significant fraction of benzene being irreversibly adsorbed onto both pure sand and PAC, and that desorption-resistant fraction (q (irr)) increased with PAC content. Desorption kinetic modeling showed that desorption of benzene was biphasic with much higher (4-40 times) rate constant for rapid process (k (1)) than that for slow process (k (2)), and that the difference in the rate constant increased with PAC content. The labile fraction (F) of desorption site showed a decreasing tendency with PAC. The experimental results would provide valuable information on remediation methods for soils and groundwater contaminated with BTEX.

  1. Comparative Analysis of Experiment Treating Benzene and CEES by Pulse Corona Plasma

    Institute of Scientific and Technical Information of China (English)

    Yan Xuefeng; Hu Zhen


    Based on an experiment treating benzene and 2-chloroethyl ethyl sulfide ( CEES )by pulse corona induced-plasma, the similarities and differences found in the experimental data and analytical results are analyzed in a comparative manner in this paper. The theory applied is also discussed.

  2. 46 CFR Appendix A to Subpart C to... - Sample Substance Safety Data Sheet, Benzene (United States)


    ... equipment and with at least one other person present who will stay outside. A life line should be used. (d... without cost to you. In addition, if you are accidentally exposed to benzene (either by ingestion... procedure. You are entitled to observe the steps taken in the measurement procedure and to record...

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

    NARCIS (Netherlands)

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


    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, ethy

  4. Hematopoietic effects of benzene inhalation assessed by long-term bone marrow culture. (United States)

    Abraham, N G


    The strong and long-lasting hematotoxic effect after benzene exposure in vivo (300 ppm, 6 hr/day, 5 days/week for 2 weeks) was assessed in mice with bone marrow cells grown in long-term bone marrow culture (LTBMC). Bone marrow cultures initiated 1 day after the last benzene exposure did not produce adequate numbers of hematopoietic cells over 3 weeks, and, in most cases, no erythroid or myeloid clonogenic cells could be recovered. The adherent cell layer of these cultures had a lowered capacity for supporting in vitro hematopoiesis after the second seeding with normal bone marrow cells compared with control cultures. Two weeks after the last benzene exposure, body weight, hematocrit, bone marrow cellularity, and committed hematopoietic progenitor content (BFU-E and CFU-GM) were regenerated to normal or subnormal values, whereas hematopoiesis in LTBMC was very poor. Over 8 weeks, little or no significant committed progenitor production was observed. Treatment of mice exposed to benzene with hemin (three doses of 3 micrograms/g bw i.v. over 2 weeks for a total dose of 9 micrograms/g) partially overcame the toxic effect of benzene on the hematopoietic system as measured by the LTBMC method. Cultures from mice treated with hemin had a modest recovery of BFU-E and CFU-GM clonogenic potential after 5 to 6 weeks in LTBMC. In contrast, little or no recovery was obtained for the adherent cell layer clonogenic capacity, even after hemin treatment. These results clearly indicate a strong, long-lasting toxic effect on the bone marrow stroma and a limited recovery of hematopoietic potential by clonogenic cells of the nonadherent population after in vivo hemin treatment.

  5. Environmental, dietary, demographic, and activity variables associated with biomarkers of exposure for benzene and lead. (United States)

    Roy, A; Georgopoulos, P G; Ouyang, M; Freeman, N; Lioy, P J


    Classification and regression tree methods represent a potentially powerful means of identifying patterns in exposure data that may otherwise be overlooked. Here, regression tree models are developed to identify associations between blood concentrations of benzene and lead and over 300 variables of disparate type (numerical and categorical), often with observations that are missing or below the quantitation limit. Benzene and lead are selected from among all the environmental agents measured in the NHEXAS Region V study because they are ubiquitous, and they serve as paradigms for volatile organic compounds (VOCs) and heavy metals, two classes of environmental agents that have very different properties. Two sets of regression models were developed. In the first set, only environmental and dietary measurements were employed as predictor variables, while in the second set these were supplemented with demographic and time-activity data. In both sets of regression models, the predictor variables were regressed on the blood concentrations of the environmental agents. Jack-knife cross-validation was employed to detect overfitting of the models to the data. Blood concentrations of benzene were found to be associated with: (a) indoor air concentrations of benzene; (b) the duration of time spent indoors with someone who was smoking; and (c) the number of cigarettes smoked by the subject. All these associations suggest that tobacco smoke is a major source of exposure to benzene. Blood concentrations of lead were found to be associated with: (a) house dust concentrations of lead; (b) the duration of time spent working in a closed workshop; and (c) the year in which the subject moved into the residence. An unexpected finding was that the regression trees identified time-activity data as better predictors of the blood concentrations than the measurements in environmental and dietary media.

  6. A semiconductor gas sensor system for high throughput screening of heterogeneous catalysts for the production of benzene derivatives (United States)

    Yamada, Yusuke; Ueda, Atsushi; Shioyama, Hiroshi; Maekawa, Toru; Kanda, Keisen; Suzuki, Kengo; Kobayashi, Tetsuhiko


    We used a semiconductor gas sensor system developed for odour discrimination for a rapid quantification of benzene derivatives which can be formed as the product of a catalytic reaction. Phenol can be obtained by the selective oxidation of benzene. The sensor system shows higher sensitivity to phenol than benzene. In particular, a SnO2 sensor sensitized with ZrO2 responds selectively to phenol. Aniline is provided as a reaction product between ammonia and benzene. The output signal of the gas sensor system increases when it is exposed to air containing aniline at the ppm level; on the other hand, the sensor output resulting from 1% ammonia in air does not increase so much. Cumene formation can be observed by the reaction of propane and benzene. The sensitivity of a SnO2 sensor sensitized with 12%SiO2-Al2O3 to cumene was about ten times higher than that to benzene. These results indicate that the semiconductor gas sensor system is useful for rapid screening of the catalyst for benzene functionalization.

  7. Review of quantitative surveys of the length and stability of MTBE, TBA, and benzene plumes in groundwater at UST sites. (United States)

    Connor, John A; Kamath, Roopa; Walker, Kenneth L; McHugh, Thomas E


    Quantitative information regarding the length and stability condition of groundwater plumes of benzene, methyl tert-butyl ether (MTBE), and tert-butyl alcohol (TBA) has been compiled from thousands of underground storage tank (UST) sites in the United States where gasoline fuel releases have occurred. This paper presents a review and summary of 13 published scientific surveys, of which 10 address benzene and/or MTBE plumes only, and 3 address benzene, MTBE, and TBA plumes. These data show the observed lengths of benzene and MTBE plumes to be relatively consistent among various regions and hydrogeologic settings, with median lengths at a delineation limit of 10 µg/L falling into relatively narrow ranges from 101 to 185 feet for benzene and 110 to 178 feet for MTBE. The observed statistical distributions of MTBE and benzene plumes show the two plume types to be of comparable lengths, with 90th percentile MTBE plume lengths moderately exceeding benzene plume lengths by 16% at a 10-µg/L delineation limit (400 feet vs. 345 feet) and 25% at a 5-µg/L delineation limit (530 feet vs. 425 feet). Stability analyses for benzene and MTBE plumes found 94 and 93% of these plumes, respectively, to be in a nonexpanding condition, and over 91% of individual monitoring wells to exhibit nonincreasing concentration trends. Three published studies addressing TBA found TBA plumes to be of comparable length to MTBE and benzene plumes, with 86% of wells in one study showing nonincreasing concentration trends.

  8. Differences in the pathways for metabolism of benzene in rats and mice simulated by a physiological model. (United States)

    Medinsky, M A; Sabourin, P J; Henderson, R F; Lucier, G; Birnbaum, L S


    Studies conducted by the National Toxicology Program on the chronic toxicity of benzene indicated that B6C3F1 mice were more sensitive to the carcinogenic effects of benzene than were F344 rats. A physiological model was developed to describe the uptake and metabolism of benzene in rats and mice. Our objective was to determine if differences in toxic effects could be explained by differences in pathways for benzene metabolism or by differences in total uptake of benzene. Compartments incorporated into the model included liver, fat, a poorly perfused tissue group, a richly perfused tissue group, an alveolar or lung compartment and blood. Metabolism of benzene was assumed to take place only in the liver and to proceed by four major competing pathways. These included formation of hydroquinone conjugates (HQC), formation of phenyl conjugates (PHC), ring-breakage and formation of muconic acid (MUC), and conjugation with glutathione with subsequent mercapturic acid (PMA) formation. Values for parameters such as alveolar ventilation, cardiac output, organ volumes, blood flow, partition coefficients, and metabolic rate constants were taken from the literature. Model simulations confirmed that during and after 6-hr inhalation exposures mice metabolized more benzene on a mumole per kilogram body weight basis than did rats. After oral exposure, rats metabolized more benzene than mice at doses above 50 mg/kg because of the more rapid absorption and exhalation of benzene by mice. Model simulations for PHC and PMA, generally considered to be detoxification metabolites, were similar in shape and dose-response to those for total metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Theoretical Study of the Benzene Cation%苯分子离子的理论研究

    Institute of Scientific and Technical Information of China (English)

    刘亚军; 邝平先; 黄明宝


    The Jahn-Teller distorted states, 2B2g and 2B1g of the benzene radical cation have been studied by using ab initio MPn and SDCI methods. The calculations indicate that 2B2g is the ground state of the benzene cation and that 2B1g is higher in energy than 2B2g and represents a saddle point. The calculated isotropic and anisotropic hyperfine coupling constants for the 2B2g state are in excellent agreement with those obtained from the ESR experiments. It is concluded that the benzene cation is in the 2B2g Jahn-Teller distorted state.

  10. Solvent-induced chemical shifts of methoxyl nuclear resonance signals in chalcones by benzene and trifluoroacetic acid (United States)

    Khurana, Shashi K.; Krishnamoorthy, V.; Parmar, Virinder S.

    The 1H NMR spectra of eight different methoxylated chalcones have separately been recorded, (1) in deuterated chloroform; (2) in a mixture (1:1) of deuterated chloroform and benzene; and (3) in a mixture of deuterated chloroform, benzene and trifluoroacetic acid (2:2:1) and the benzene induced and TFA induced shift values have been assigned to different methoxyl groups. These shift values can serve as a guide in determining the structures of natural or new chalcones. The steric, electronic and conformational factors are discussed to explain the shift values.

  11. 32. Study the aneugenic effect of benzene on germ cell of animal and workers

    Institute of Scientific and Technical Information of China (English)


    Objective: To study the aneupoidy effect of benzene on germ cells of animal and humans. Method: The NIH adult female mice were treated with varies doses of benzene (942, 1881 and 3762mg/kg respectively) by single gavage and (706, 1922 and 4864mg/m3 respectively) by inhalation (2h/d, 15d), the ovulated oocytes were collected for conventional cytogenetic analyses, and the frequencies of aneuploidy were detected. The frequencies of aneuploidy in sperm of benzene exposed workers were detected by two color fluorescence in situ hybridization with digoxingenin labeled 9 chromosome probe(D9Z1) and biotin labeled 18 chromosome probe (D18Z1). Result: The frequencies of aneuploidy in MII oocytes were significantly increased over the control in three groups treated by inhalation (7.06%,7.50% and 7.76% respectively control 1.30%, P<0.05 ), a dose-dependent response was present, But in gavage groups only the high dose group was increased over that of control. P<0.05. The timeweight average air concentration (TWA) of benzene in the workplace was 86.49mg/m3, it was two fold higher than the national maximum allowable concentration. The concentration of urinary trans, trans-muconic acid (ttMA) in exposed group was significantly higher than that of control group. A total of 136 401 sperm nuclei in 14 exposed workers and 156 955 sperm nuclei in 16 control workers were counted. The results showed that the frequencies of disomic sperm for chromosome 9 and 18, and diploidy sperm in exposed-workers (0.168%, 0.055%, 0.073%, respectively) were statistically increased over that (0.050%、 0. 033% and 0.040%, respectively) of controls. P<0.05. The frequencies of nullisomic sperm for chromosome 9,18 in the exposed group (0.206%,0.068%) were statistically increased also over that (0.067%,0.048% respectively) of control. The frequency of overall numerical chromosome aberrations (0.570%) in tbe exposed group was increased over that of control(0.218%)P<0.05.Conclusion:An increased aneuploidy

  12. Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Spycher, N.; Xu, T.; Apps, J.; Kharaka, Y.; Birkholzer, J.T.


    In this study, reactive transport simulations were used to assess the mobilization and transport of organics with supercritical CO{sub 2} (SCC), and the co-injection and transport of H{sub 2}S with SCC. These processes were evaluated at conditions of typical storage reservoirs, and for cases of hypothetical leakage from a reservoir to an overlying shallower fresh water aquifer. Modeling capabilities were developed to allow the simulation of multiphase flow and transport of H{sub 2}O, CO{sub 2}, H{sub 2}S, as well as specific organic compounds (benzene), coupled with multicomponent geochemical reaction and transport. This included the development of a new simulator, TMVOC-REACT, starting from existing modules of the TOUGH2 family of codes. This work also included an extensive literature review, calculation, and testing of phase-partitioning properties for mixtures of the phases considered. The reactive transport simulations presented in this report are primarily intended to illustrate the capabilities of the new simulator. They are also intended to help evaluate and understand various processes at play, in a more qualitative than quantitative manner, and only for hypothetical scenarios. Therefore, model results are not intended as realistic assessments of groundwater quality changes for specific locations, and they certainly do not provide an exhaustive evaluation of all possible site conditions, especially given the large variability and uncertainty in hydrogeologic and geochemical parameter input into simulations. The first step in evaluating the potential mobilization and transport of organics was the identification of compounds likely to be present in deep storage formations, and likely to negatively impact freshwater aquifers if mobilized by SCC. On the basis of a literature review related to the occurrence of these organic compounds, their solubility in water and SCC, and their toxicity (as reflected by their maximum contaminant levels MCL), benzene was

  13. Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Spycher, N.; Xu, T.; Apps, J.; Kharaka, Y.; Birkholzer, J.T.


    In this study, reactive transport simulations were used to assess the mobilization and transport of organics with supercritical CO{sub 2} (SCC), and the co-injection and transport of H{sub 2}S with SCC. These processes were evaluated at conditions of typical storage reservoirs, and for cases of hypothetical leakage from a reservoir to an overlying shallower fresh water aquifer. Modeling capabilities were developed to allow the simulation of multiphase flow and transport of H{sub 2}O, CO{sub 2}, H{sub 2}S, as well as specific organic compounds (benzene), coupled with multicomponent geochemical reaction and transport. This included the development of a new simulator, TMVOC-REACT, starting from existing modules of the TOUGH2 family of codes. This work also included an extensive literature review, calculation, and testing of phase-partitioning properties for mixtures of the phases considered. The reactive transport simulations presented in this report are primarily intended to illustrate the capabilities of the new simulator. They are also intended to help evaluate and understand various processes at play, in a more qualitative than quantitative manner, and only for hypothetical scenarios. Therefore, model results are not intended as realistic assessments of groundwater quality changes for specific locations, and they certainly do not provide an exhaustive evaluation of all possible site conditions, especially given the large variability and uncertainty in hydrogeologic and geochemical parameter input into simulations. The first step in evaluating the potential mobilization and transport of organics was the identification of compounds likely to be present in deep storage formations, and likely to negatively impact freshwater aquifers if mobilized by SCC. On the basis of a literature review related to the occurrence of these organic compounds, their solubility in water and SCC, and their toxicity (as reflected by their maximum contaminant levels MCL), benzene was

  14. OH-initiated oxidation of benzene - Part II. Influence of elevated NOx concentrations

    DEFF Research Database (Denmark)

    Klotz, B; Volkamer, R; Hurley, MD


    -containing species in high yield. The results from the present work also show that experimental studies aimed at establishing/verifying chemical mechanisms for aromatic hydrocarbons must be performed using NOx levels which are representative of those found in the atmosphere......., respectively). In contrast to results from previous studies, a pronounced dependence of the product distribution on the NOx concentration was observed. The phenol yield decreases from approximately 50-60% in the presence of low concentrations (10 000 ppb) NOx concentrations. In the presence of high......The present work represents a continuation of part I of this series of papers, in which we investigated the phenol yields in the OH-initiated oxidation of benzene under conditions of low to moderate concentrations of NOx, to elevated NOx levels. The products of the OH-initiated oxidation of benzene...

  15. Hydrogen Absorption Thermodynamic Properties of Rare Earth Based Hydrogen Storage Alloy in Benzene

    Institute of Scientific and Technical Information of China (English)

    蔡官明; 陈长聘; 安越; 徐国华; 陈立新; 王启东


    The hydriding/dehydriding thermodynamic properties of the slurry system formed by suspending La-rich mischmetal nickel hydrogen storage alloy (MlNi5) in Benzene (C6H6) were investigated. The pressure-composition isotherms for both the alloy powder and the slurry suspended with MlNi5 were measured at several temperatures(10, 20, 30, 40 ℃). The standard enthalpy of formation ΔH° and standard entropy of formation ΔS° for the alloy powder with and without benzene were determined respectively. The experimental results show that the values of ΔH° and ΔS° for the hydriding reaction of hydrogen storage alloy (MlNi5) of the slurry system and the gas-solid system are all very close.

  16. Volumetric properties of binary mixtures of benzene with cyano-based ionic liquids (United States)

    Gonfa, Girma; Bustam, Mohamad Azmi; Moniruzzaman, Muhammad; Murugesan, Thanabalan


    The objective of this study is to investigate the volumetric properties of the binary mixtures comprised benzene and two ionic liquids, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and 1-butyl-3-methyl- imidazolium dicyanamide ([ BMIM ][ N ( CN )2]( . Densities (ρ) and viscosities (μ) of the binary mixtures were measured over a temperature range of 293.15 to 323.15 K and at atmospheric pressure. Excess molar volumes and viscosity deviations were calculated from the experimental densities and viscosities values. The volumetric properties of the mixtures were changed significantly with the change of compositions and temperatures. It was also found that the value of excess molar volume and viscosity deviations were negative (-ve) over the entire range of compositions. The results have been interpreted in terms of molecular interactions of ILs and benzene.

  17. Hydroxylation of Benzene to Phenol via Hydrogen Peroxide in Hydrophilic Triethylammonium Acetate Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-ke; ZHU Liang-fang; GUO Bin; LIU Qiu-yuan; LI Gui-ying; HU Chang-wei


    A new Fenton-like system in a medium of hydrophilic triethylammonium type of ionic liquid(IL) was used for the hydroxylation of benzene to phenol. The triethylammonium acetate([Et3NH][CH3COO]) IL exhibited retardation performance for the decomposition of H2O2 and protection performance for the further oxidation of phenol,thus the yield and selectivity to phenol were promoted greatly. The acidity of the system was proved to be an important factor for the selectivity to phenol. The utilization of H2O2 and the selectivity to phenol, as well as the Turnover number(TON) of the catalyst were effectively enhanced by a benzene-[Et3NH][CH3COO] bi-phase system. The catalyst with [Et3NH][CH3COO] IL was recycled with stable catalytic performance.

  18. An expanded cohort study of cancer among benzene-exposed workers in China

    Energy Technology Data Exchange (ETDEWEB)

    Song-Nian Yin; Gui-Lan Li; Zhi-Nan Zhang [Chinese Academy of Preventive Medicine, Bejing (China)] [and others


    An expanded cohort study of 74,828 benzene-exposed and 35,805 unexposed workers were followed during 1972 to 1987, based on a previous study in 12 cities in China. A small increase was observed in total cancer mortality among benzene-exposed compared with unexposed Workers (relative risk [RR] = 1-2). Statistically significant excesses were noted for leukemia (RR = 2.3), malignant lymphoma (RR = 4.5), and lung cancer (RR = 1.4). When risks were evaluated by leukemia subtype, only acute myelogenous leukemia was significantly elevated (RR = 3.1), although nonsignificant excesses were also noted for chronic myelogenous leukemia (RR = 2.6) and acute lymphocytic leukemia (RR = 2.3). A significant excess was also found for aplastic anemia. 19 refs., 5 tabs.

  19. Crystal structure of 1-bromo-2-(phenyl­selen­yl)benzene (United States)

    Charette, Bronte J.; Ritch, Jamie S.


    In the title compound, C12H9BrSe, the Se atom exhibits a bent geometry, with a C—Se—C bond angle of 99.19 (6)°. The ortho Se and Br atoms are slightly displaced from opposite faces of the mean plane of the benzene ring [by 0.129 (2) and 0.052 (2) Å, respectively]. The planes of the benzene and phenyl rings form a dihedral angle of 72.69 (5)°. In the crystal, π-stacking inter­actions between inversion-related phenyl rings are observed, with a centroid–centroid distance of 3.630 (1) Å. PMID:25844201

  20. Kinetics of benzene hydrogenation on supported platinum, palladium, rhodium and ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, K.; Fueda, Y.; Kusunoiki, K.; Uchino, T.


    Although benzene hydrogenation has been widely utilized as a test reaction for the investigation of catalytic activity, the reaction mechanism has not been well elucidated. As to the Langmuir-Hinshelwood rate equations, there have been many reports for the reaction on nickel catalysts, but few papers have been published on platinum metal catalysts, especially on rhodium and ruthenium catalysts. In this communication, reaction rates were measured for benzene hydrogenation over commercially available Pt-, Pd-, Rh- and Ru-Al/sub 2/O/sub 3/ catalysts and the rate equation was derived. The thermodynamic consistency of the rate equation was then tested in the light of the rules established by Boudart et al. and Vannice et al.

  1. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo (United States)

    Azadi, Sam; Cohen, R. E.


    We studied the low-pressure (0-10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo and density functional theory (DFT) methods. We performed diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. Using density functional perturbation theory, we computed the phonon contributions to the free energies. Our DFT enthalpy-pressure phase diagrams indicate that the Pbca and P21/c structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature Pbca to P21/c phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations give 50.6 ± 0.5 kJ/mol for crystalline benzene lattice energy.

  2. First principles computation of lattice energies of organic solids: the benzene crystal. (United States)

    Ringer, Ashley L; Sherrill, C David


    We provide a first-principles methodology to obtain converged results for the lattice energy of crystals of small, neutral organic molecules. In particular, we determine the lattice energy of crystalline benzene using an additive system based on the individual interaction energies of benzene dimers. Enthalpy corrections are estimated so that the lattice energy can be directly compared to the experimentally determined sublimation energy. Our best estimate of the sublimation energy is 49.4 kJ mol(-1), just over the typical experimentally reported values of 43-47 kJ mol(-1). Our results underscore the necessity of using highly correlated electronic structure methods to determine thermodynamic properties within chemical accuracy. The first coordination sphere contributes about 90 % of the total lattice energy, and the second coordination sphere contributes the remaining 10 %. Three-body interactions are determined to be negligible.

  3. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex (United States)

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng


    Electronic structures and coherent quantum transport properties are explored for spin-crossover molecule iron-benzene Fe(Bz)2 using density functional theory combined with non-equilibrium Green's function. High- and low-spin states are investigated for two different lead-molecule junctions. It is found that the asymmetrical T-shaped contact junction in the high-spin state behaves as an efficient spin filter while it has a smaller conductivity than that in the low-spin state. Large spin Seebeck effect is also observed in asymmetrical T-shaped junction. Spin-polarized properties are absent in the symmetrical H-shaped junction. These findings strongly suggest that both the electronic and contact configurations play significant roles in molecular devices and metal-benzene complexes are promising materials for spintronics and thermo-spintronics.

  4. Exposure to benzene, toluene, xylenes and total hydrocarbons among snowmobile drivers in Sweden. (United States)

    Eriksson, Kåre; Tjärner, Dan; Marqvardsen, Inger; Järvholm, Bengt


    The exposure to benzene, toluene, xylenes and total hydrocarbons among 25 individuals exposed to exhaust from a snowmobile equipped with a two-stroke engine has been evaluated. Sampling was performed by pumped and diffusive sampling in parallel. There was a relatively bad agreement between the two air-sampling methods. The bad agreement can in part be explained by back diffusion of the substances from the samplers, a high face velocity, and deposition of droplets of unburned gasoline onto or in the vicinity of the samplers. The levels of benzene ranged from not detectable (engine equipped with a catalyst could reduce the exposure. To reduce the exposure for the passenger on a sleigh an extension of the exhaust pipe may be effective.

  5. Thermodynamic Investigation of the Azeotropic Mixture Composed of Water and Benzene

    Institute of Scientific and Technical Information of China (English)

    NAN,Zhao-Dong(南照东); TAN,Zhi-Cheng(谭志诚)


    The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adiabatic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature range from 265.409 to 275.165 K and 275.165 to 279.399 K. The phase transition temperatures were determined to be 272.945 and 278.339 K, which were corresponding to the solid-liquid phase transitions of water and benzene, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived from the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.

  6. Carbo-quinoids: stability and reversible redox-proaromatic character towards carbo-benzenes. (United States)

    Cocq, Kévin; Maraval, Valérie; Saffon-Merceron, Nathalie; Saquet, Alix; Poidevin, Corentin; Lepetit, Christine; Chauvin, Remi


    The carbo-mer of the para-quinodimethane core is stable within in a bis(9-fluorenylidene) derivative. Oxidation of this carbo-quinoid with MnO2 in the presence of SnCl2 and ethanol affords the corresponding p-bis(9-ethoxy-fluoren-9-yl)-carbo-benzene. The latter can be in turn converted back into the carbo-quinoid by reduction with SnCl2 , thus evidencing a chemical reversibility of the interconversion between a pro-aromatic carbo-quinoid and an aromatic carbo-benzene, and is reminiscent of the behavior of the benzoquinone/hydroquinone redox couple (in the red-ox opposite sense).

  7. VSMP for Modeling the Biodegradability of Substituted Benzenes Based on Electrotopological State Indices for Atom Types

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Shen; YIN Da-Qiang; CUI Shi-Hai; WANG Lian-Sheng


    The electrotopological state (E-state) index was employed to characterize the structures of 51 substituted benzenes. Eleven E-state indices of the compounds were calculated by the computer program developed in our laboratory. The method for variable selection and modeling based on prediction (VSMP) was used to select an optimal combination of the variables from 11 E-state descriptors. Then the optimal descriptors were employed to model the relationship between the relative biodegradability of the substituted benzenes and their molecular structures. A novel 5-descriptor linear model was developed and the model has a high quality with the correlation coefficient and the root mean square error in estimation step being 0.9378 and 0.35, respectively, and these in leave-one-out cross-validation procedure being 0.9210 and 0.39, respectively.

  8. Ways of reducing the bromine numbers of benzene for nitration with the use of the piperylene additive

    Energy Technology Data Exchange (ETDEWEB)

    Kolyandr, L.Ya.; Litvinenko, A.M.; Mastyukov, V.A.; Potapchenko, A.A.; Savikkova, M.T.; Shoherbakova, T.G.; Shuzhenko, E.A.; Titarenko, V.G.; Tkachenko, L.A.


    To study the diminution of the bromine numbers of benzene for nitration, an investigation has been made of the impurities according to the fractions of the tests of benzene production of three coke and chemical works: the works in Makeev-a, ka, Bagleisk and Yenakievo. It has been found that when the piperylene additive is used, the value of the bromine numbers of benzene for nitration is determined, in the main, not by the piperylenes removed during purification. When the intermediate BT fractions are not sufficiently clearly selected, the value of the bromine numbers of benzene is influenced also by the impurities which are concentrated in its terminal fractions. To radically remove piperylenes, it is necessary to improve the contact between the acid and the fraction being purified; this is attained by intensifying mixing and lengthening the purification process.

  9. On the Formation of Benzoic Acid and Higher Order Benzene Carboxylic Acids in Interstellar Model Ices grains (United States)

    McMurtry, Brandon M.; Saito, Sean E. J.; Turner, Andrew M.; Chakravarty, Harish K.; Kaiser, Ralf I.


    With a binary ice mixture of benzene (C6H6) and carbon dioxide (CO2) at 10 K under contamination-free ultrahigh vacuum conditions, the formation of benzene carboxylic acids in interstellar ice grains was studied. Fourier transform infrared spectroscopy was used to probe for the formation of new species during the chemical processing of the ice mixture and during the following temperature-programmed desorption. Newly formed benzene carboxylic acid species, i.e., benzoic acid, as well as meta- and para-benzene dicarboxylic acid, were assigned using newly emerging bands in the infrared spectrum; a reaction mechanism, along with rate constants, was proposed utilizing the kinetic fitting of the coupled differential equations.

  10. Heterogeneous photocatalytic decomposition of benzene on lanthanum-doped TiO2 film at ambient temperature. (United States)

    Zhang, Shicheng; Zheng, Zhijian; Wang, Jinhe; Chen, Jianmin


    Lanthanum-doped anatase TiO2 thin films on glass prepared via a sol-gel process have been shown to have much higher photocatalytic activity for the degradation of gaseous benzene than pure anatase TiO2 thin film. The photodecomposition of benzene on both types of TiO2 films follows the first-order kinetics while the CO(2) and CO formation followed the zero-order kinetics. GC/MS identification of the intermediates produced during the photodegradation of benzene revealed that doping lanthanum into TiO2 thin film favors a cleavage of benzene ring. An optimal lanthanum amount with respect to photocatalytic activity was about 2.5 wt% (La2O3/TiO2).

  11. Highly π electron-rich macro-aromatics: bis(p-aminophenyl)-carbo-benzenes and their DBA acyclic references. (United States)

    Rives, Arnaud; Baglai, Iaroslav; Malytskyi, Volodymyr; Maraval, Valérie; Saffon-Merceron, Nathalie; Voitenko, Zoia; Chauvin, Remi


    A series of stable quadrupolar bis(p-aminophenyl)-carbo-benzenes, featuring both donor-donor-donor π-frustration and central macro-aromaticity, is described and compared to the acyclic dibutatrienylacetylene (DBA) reference series.

  12. Urinary methyl tert-butyl ether and benzene as biomarkers of exposure to urban traffic. (United States)

    Campo, Laura; Cattaneo, Andrea; Consonni, Dario; Scibetta, Licia; Costamagna, Paolo; Cavallo, Domenico M; Bertazzi, Pier Alberto; Fustinoni, Silvia


    Methyl tert-butyl ether (MTBE) and benzene are added to gasoline to improve the combustion process and are found in the urban environment as a consequence of vehicular traffic. Herein we evaluate urinary MTBE (MTBE-U) and benzene (BEN-U) as biomarkers of exposure to urban traffic. Milan urban policemen (130 total) were investigated in May, July, October, and December for a total of 171 work shifts. Personal exposure to airborne benzene and carbon monoxide (CO), and atmospheric data, were measured during the work shift, while personal characteristics were collected by a questionnaire. A time/activity diary was completed by each subject during the work shift. Spot urine samples were obtained for the determination of MTBE-U and BEN-U. Median personal exposure to CO and airborne benzene were 3.3 mg/m(3) and 9.6 μg/m(3), respectively; median urinary levels in end-of-shift (ES) samples were 147 ng/L (MTBE-U) and 207 ng/L (BEN-U). The time spent on traffic duty at crossing was about 40% of work time. Multiple linear regression models, taking into account within-subject correlations, were applied to investigate the role of urban pollution, atmospheric conditions, job variables and personal characteristics on the level of biomarkers. MTBE-U was influenced by the month of sampling and positively correlated to the time spent in traffic guarding, CO exposure and atmospheric pressure, while negatively correlated to wind speed (R(2) for total model 0.63, P<0.001). BEN-U was influenced by the month and smoking habit, and positively correlated to urinary creatinine; moreover, an interaction between CO and smoking was found (R(2)=0.62, P<0.001). These results suggest that MTBE-U is a reliable marker for assessing urban traffic exposure, while BEN-U is determined mainly by personal characteristics.

  13. Supercritical Carbon Dioxide Extraction of Benzene in Poly(vinyl acetate) and Polystyrene


    佐々木, 正和; 滝嶌, 繁樹; 舛岡, 弘勝


    In order to test the applicability of the supercritical fluid extraction technique to the separation of impurities in polymers, separation of benzene from two polymers of poly(vinyl acetate) and polystyrene was carried out using supercritical carbon dioxide. Figure 1 shows a schematic diagram of the supercritical fluid extraction apparatus. It consists of the following sections: (1) compression of carbon dioxide, (2) extraction, and (3) control and measurement of carbon dioxide flow rates...

  14. Research on polyfluorene derivatives end-capped by N-hexyl-carbazole and benzene

    Institute of Scientific and Technical Information of China (English)


    Copolymers of 9,9-dioctylfluorene (DOF) and 2-thienyl-benzothiadiazole (DBT) were synthesized by Suzuki reaction and end-capped by N-hexyl-carbazole and benzene, which were abbreviated as PDOF-DBT-Cz and PDOF-DBT-B, respectively. The photophysical, electrochemical and thermal properties of the copolymers were studied. The results indicated that replacement of N-hexyl-carbazole as end-capping group of PDOF-DBT can vary light color and improve luminescence efficiency.

  15. Calculations of Hyperpolarizabilities for Para-disubstituted Benzenes with the QSPR

    Institute of Scientific and Technical Information of China (English)

    Xian Dong ZENG; Xuan XU; Bing Feng WANG; Bing Can WANG


    A quantitative structure-property relationship (QSPR) was made for the prediction of the hyperpolarizabilities(β) of para-disubstituted benzenes with the nonlinear optical properties, and the βcal2 calculated by this model accorded better with the experimental values (βexpt) compared with theβcal1 calculated at the CPHF/6-31G*//HF/STO-3G level of theory, especially whenβ was big.

  16. A QSAR of the toxicity of amino-benzenes and their structures

    Institute of Scientific and Technical Information of China (English)

    许禄; 吴亚平; 胡昌玉; 李华


    The quantum chemical parameters and the topological indices have been calculated for the prediction of the toxicity of amino-benzenes in the environment, and work has been done on the multiple regression and neural networks. The combination of CoMFA with formation heat yields greatly improved results. A good model has been obtained which provides a basis for the studies of the toxic action mechanism.

  17. Theoretical study on second-order nonlinear optical properties of unsymmetric bis (phenylethynyl) benzene series derivatives

    Institute of Scientific and Technical Information of China (English)

    FU, Wei; FENG, Ji-Kang; YU, Kun-Qian; REN, Ai-Min; CUI, Meng


    On the basis of Z1NDO methods, according to the sum-overstates (SOS) expression, the progran for the calculation of the second-order nonlinear optical susceptibilities βuk and βμ ofmolecules was devised, and the structures and nonlinear optical properties of unsymmetric bis (phenylethynyl) benzene series derivatives were studied. The influence of the molecular conjugated chain lengths, the donor and the acceptor on βμwas examined.

  18. Benzene-fused BODIPYs: Synthesis and the impact of fusion mode

    KAUST Repository

    Ni, Yong


    BODIPY derivatives with one or two benzene units fused at different positions are prepared using novel synthetic methods. The resulting dye 1 shows deep red fluorescence with a large Stokes shift. Dyes 2 and 3 are reported for the first time and 3 exhibits near infrared absorption. The impact of benzannulation at different positions of BODIPY is discussed, and the geometry and electronic structure are studied by DFT calculations. This journal is © 2013 The Royal Society of Chemistry.

  19. Angiogenic Potential of 3-Nitro-4-Hydroxy Benzene Arsonic Acid (Roxarsone)



    Background Roxarsone (3-nitro-4-hydroxy benzene arsonic acid) is an arsenic compound widely used in the poultry industry as a feed additive to prevent coccidiosis, stimulate growth, and to improve tissue pigmentation. Little is known about the potential human health effects from roxarsone released into the environment from chicken waste or from residual compound in chicken products. Objective The growth potentiation and enhanced tissue pigmentation suggest that low levels of roxarsone exposur...

  20. Small-angle neutron scattering studies of sodium butyl benzene sulfonate aggregates in aqueous solution

    Indian Academy of Sciences (India)

    O R Pal; V G Gaikar; J V Joshi; P S Goyal; V K Aswal


    The aggregation behaviour of a hydrotrope, sodium -butyl benzene sulfonate (Na-NBBS), in aqueous solutions is investigated by small-angle neutron scattering (SANS). Nearly ellipsoidal aggregates of Na-NBBS at concentrations well above its minimum hydrotrope concentration were detected by SANS. The hydrotrope seems to form self-assemblies with aggregation number of 36–40 with a substantial charge on the aggregate. This aggregation number is weakly affected by the hydrotrope concentration.

  1. Fluorescent naphthalene-based benzene tripod for selective recognition of fluoride in physiological condition

    Indian Academy of Sciences (India)

    Barun kumar Datta; Chirantan Kar; Gopal Das


    Aluminium complex of a naphthalene-based benzene tripod ligand system has been reported for the selective recognition of fluoride in aqueous medium in physiological condition. The ligand can selectively recognize Al3+ through enhancement in the fluorescence intensity and this in situ formed aluminium complex recognizes fluoride through quenching of fluorescence. The receptor system detects fluoride in nanomolar range. The sensing property was extended for practical utility to sense fluoride in tap water, pond water and river water.

  2. Study on Testing the Composition of Indoor Air Pollution to Benzene Series by Laser Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    XUE Mei; HE Le-min; ZHONG Wei-gang; ZHAO Xin; LI Xiu-zhen


    This paper reports some experimental detecting results of pollutants in the atmosphere by means of laser mass spectrometry. For toluene as calibration gas, the calibration procedure was also given. Benzene, toluene and xylene were discovered in testing indoor atmosphere resulting from dope in the course of fitment. Meanwhile, it is noticeable that the concentration of various harmful elements is obviously decreasing as time goes on.

  3. Exophiala sideris, a novel black yeast isolated from environments polluted with toxic alkyl benzenes and arsenic. (United States)

    Seyedmousavi, Seyedmojtaba; Badali, Hamid; Chlebicki, Andrzej; Zhao, Jingjun; Prenafeta-Boldú, Francesc Xavier; De Hoog, G Sybren


    A novel species of the black yeast genus Exophiala (order Chaetothyriales) is described. Strains were repeatedly obtained by enriching samples of wild berries from different plants, guano-rich soil and from oak railway ties treated with arsenic creosote under a toluene-rich atmosphere. An identical strain was encountered in a closed arsenic mine polluted by alkyl benzenes. Its potential use for purposes of bioremediation is discussed.

  4. GC-HS Method Development for the Estimation of Benzene Content in Lovastatin

    Directory of Open Access Journals (Sweden)

    Patel D


    Full Text Available A simple, fast and accurate method has been developed for the estimation of benzene content inLovastatin by Gas Chromatography. The analysis was carried out on Perkin Elmer Clarus 600 GC-HSChromatograph. The column used was DB-624 30m X 0.32 mm X 1.8 μm fused silica analytical column(6% cyanopropylphenyl 94 % dimethylpolysiloxane as a stationary phase.The detector used wasFID detector.

  5. Mechanistic Insights into Ring Cleavage and Contraction of Benzene over a Titanium Hydride Cluster. (United States)

    Kang, Xiaohui; Luo, Gen; Luo, Lun; Hu, Shaowei; Luo, Yi; Hou, Zhaomin


    Carbon-carbon bond cleavage of benzene by transition metals is of great fundamental interest and practical importance, as this transformation is involved in the production of fuels and other important chemicals in the industrial hydrocracking of naphtha on solid catalysts. Although this transformation is thought to rely on cooperation of multiple metal sites, molecular-level information on the reaction mechanism has remained scarce to date. Here, we report the DFT studies of the ring cleavage and contraction of benzene by a molecular trinuclear titanium hydride cluster. Our studies suggest that the reaction is initiated by benzene coordination, followed by H2 release, C6H6 hydrometalation, repeated C-C and C-H bond cleavage and formation to give a MeC5H4 unit, and insertion of a Ti atom into the MeC5H4 unit with release of H2 to give a metallacycle product. The C-C bond cleavage and ring contraction of toluene can also occur in a similar fashion, though some details are different due to the presence of the methyl substituent. Obviously, the facile release of H2 from the metal hydride cluster to provide electrons and to alter the charge population at the metal centers, in combination with the flexible metal-hydride connections and dynamic redox behavior of the trimetallic framework, has enabled this unusual transformation to occur. This work has not only provided unprecedented insights into the activation and transformation of benzene over a multimetallic framework but it may also offer help in the design of new molecular catalysts for the activation and transformation of inactive aromatics.

  6. Pd(II/HPMoV-Catalyzed Direct Oxidative Coupling Reaction of Benzenes with Olefins

    Directory of Open Access Journals (Sweden)

    Yasutaka Ishii


    Full Text Available The direct aerobic coupling reaction of arenes with olefins was successfully achieved by the use of Pd(OAc2/molybdovanadophosphoric acid (HPMoV as a key catalyst under 1 atm of dioxygen. This catalytic system could be extended to the coupling reaction of various substituted benzenes with olefins such as acrylates, aclrolein, and ethylene through the direct aromatic C-H bond activation.




    Detergents contain synthetic or organic surface active agents called surfactants, which are derived from petroleum product precursors. They have the common property of lowering the surface tensions of water thus allowing dirt or grease adhered to various articles to be washed off. Linear alkyl benzene sulfonate (LAS) is a most commonly used anionic surfactant. Discharge of raw or treated wastewater containing this chemical substance into the environment causes major public health and envirome...

  8. Combined effects of cadmium and linear alkyl benzene sulfonate on Lemna minor L. (United States)

    Singh, J; Chawla, G; Naqvi, S H; Viswanathan, P N


    : The effects of 0.1 ppm cadmium and 0.005% linear alkyl benzene sulfonates (LAS) on the uptake and metabolic incorporation of (14)C glycine by Lemna minor L., after 2, 24 and 48 h were studied for antagonistic/synergistic effects. Combined exposure was found to decrease the (14)C incorporation into proteins, DNA, RNA and phospholipids, to a greater extent than individual exposure. The presence of LAS increased the uptake of (109)Cd in the plants.

  9. Pathomorphological changes in gills of fish fingerlings (Cirrhina mrigala) by linear alkyl benzene sulfonate. (United States)

    Misra, V; Lal, H; Chawla, G; Viswanathan, P N


    Fish fingerlings (Cirrhina mrigala) exposed to 0.005 ppm (25% of LC50) concentration to detergents (linear alkyl benzene sulfonate) showed marked behavioral changes and distorted appearance of primary and secondary lamellae along with damage to gill epithelium under scanning electron microscopy at various magnifications. Mucosal cells of gills were found to secrete mucus showing primary reactions for membrane damage leading to dysfunction in respiration and osmoregulation.

  10. Kinetics Modelling of the Biodegradation of Benzene, Toluene and Phenol as Single Substrate and Mixed Substrate by Using Pseudomonas putida


    Mathur, A K; Majumder, C. B.


    In the present work, kinetics of the biodegradation of benzene, toluene and phenol by using a pure culture of Pseudomonas putida (MTCC 1194) was determined by measuring the specific growth rate and degradation rate with substrate concentration as a function of time in a batch reactor. In general, the degradation rate of benzene, toluene and phenol increased with the increase in the initial substrate concentration and then decreased after reaching a maximum, showing substrate inhibition kineti...

  11. Evidence for strain-specific differences in benzene toxicity as a function of host target cell susceptibility. (United States)

    Neun, D J; Penn, A; Snyder, C A


    It has long been recognized that benzene exposure produces disparate toxic responses among different species or even among different strains within the same species. There is ample evidence that species- or strain-dependent differences in metabolic activity correlate with the disparate responses to benzene. However, bone marrow cells (the putative targets of benzene toxicity) may also exhibit species- or strain-dependent differences in susceptibility to the toxic effects of benzene. To investigate this hypothesis, two sets of companion experiments were performed. First, two strains of mice, Swiss Webster (SW) and C57B1/6J (C57), were exposed to 300 ppm benzene via inhalation and the effects of the exposures were determined on bone marrow cellularity and the development of bone marrow CFU-e (Colony Forming Unit-erythroid, an early red cell progenitor). Second, bone marrow cells from the same strains were exposed in vitro to five known benzene metabolites (1,4 benzoquinone, catechol, hydroquinone, muconic acid, and phenol) individually and in binary combinations. Benzene exposure, in vivo, reduced bone marrow cellularity and the development of CFU-e in both strains; however, reductions in both these endpoints were more severe in the SW strain. When bone marrow cells from the two strains were exposed in vitro to the five benzene metabolites individually, benzoquinone, hydroquinone, and catechol reduced the numbers of CFU-e in both strains in dose-dependent responses, phenol weakly reduced the numbers of the C57 CFU-e only and in a non-dose-dependent manner, and muconic acid was without effect on cells from either strain.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Highly selective ethylbenzene production through alkylation of dilute ethylene with gas phase-liquid phase benzene and transalkylation feed

    Institute of Scientific and Technical Information of China (English)

    Shenglin Liu; Fucun Chen; Sujuan Xie; Peng Zeng; Xiyan Du; Longya Xu


    A novel industrial process was designed for the highly selective production of ethylbenzene.It comprised of a reactor vessel,vapor phase ethylene feed stream,benzene and transalkylation feed stream.Especially the product stream containing ethylbenzene was used to heat the reactor vessel,which consisted of an alkylation section,an upper heat exchange section,and a bottom heat exchange section.In such a novel reactor,vapor phase benzene and liquid phase benzene were coexisted due to the heat produced by isothermal reaction between the upper heat exchange section and the bottom heat exchange section.The process was demonstrated by the thermodynamic analysis and experimental results.In fact,during the 1010 hour-life-test of gas phase ethene with gas phase-liquid phase benzene alkylation reaction,the ethene conversion was above 95%,and the ethylbenzene selectivity was above 83% (only benzene feed) and even higher than 99% (benzene plus transalkylation feed).At the same time,the xylene content in the ethylbenzene was less than 100 ppm when the reaction was carried out under the reaction conditions of 140-185℃ of temperature,1.6-2.1 MPa of pressure,3.0-5.5 of benzene/ethylene mole ratio,4-6 v% of transalkylation feed/(benzene+transalkylation feed),0.19-0.27 h-1 of ethene space velocity,and 1000 g of 3998 catalyst loaded.Thus,compared with the conventional ethylbenzene synthesis route,the transalkylation reactor could be omitted in this novel Industrial process.

  13. On the mechanistic differences of benzene-induced leukemogenesis between wild type and p53 knockout mice

    Energy Technology Data Exchange (ETDEWEB)

    Hirabayashi, Yoko; Yoon, Byung-Il; Kawasaki, Yasushi; Li, Guang-Xun; Kanno, Jun; Inoue, Tohru [National Inst. of Health Sciences, Tokyo (Japan)


    Leukemia induction by benzene inhalation was first reported by Le Noire in 1887, described multiple cases of leukemia among Parisian cobblers. However, experimental induction of leukemia by benzene exposure was not succeeded for a hundred years, until Snyder et al. and our group reported it nearly 20 years ago. Nevertheless, the mechanistic background of benzene-induced leukemia was still an enigma until recently a benzene-induced peculiar cell kinetics of the stem/progenitor cells has been elucidated by our study, demonstrated a marked repeated oscillatory decrease in peripheral blood and bone marrow (BM) cellularity during and after benzene exposure, which epigenetically preceded and developed the leukemia more than a year later. We utilized the BUUV (bromodeoxyuridine + UV exposure) method to study stem/progenitor cell kinetics during and/or after benzene exposure. Using these methods, we were able to measure the labeling rate, cycling fraction of clonogenic progenitor cells, and other cell cycle parameters. The cycling fraction of stem/progenitor cells was found not to turn into an active hematopoiesis but to remain low during benzene inhalation and further we found evidence that the cycling fraction depression may be mediated in part by a slowing of stem/progenitor cell cycling perse by up-regulation of p21. The benzene induced leukemogenicity between mice carrying wild-type p53 and mice lacking p53 seem to differ from one another. In the case of p53 knockout mouse, DNA damage such as weak mutagenicity and or chromosomal damages are retained, and those damages participated in the induction of a consequent activation of proto-oncogenes and the like, which led cells to further neoplastic changes. In contrast, in the case of wild type mice, a dramatic oscillational change in the cell cycle of the stem cell compartment seems to be an important factor for mice carrying the p53 gene. (author)

  14. Illness Symptoms Experienced by Children Exposed to Benzene After a Flaring Incident at the BP Refinery Facility in Texas City. (United States)

    D'Andrea, Mark A; Reddy, G Kesava


    Objective To evaluate the illness symptoms experienced by children who were exposed to benzene following a flaring incident at the BP refinery in Texas City, Texas. Methods A total of 641 children, aged 5 year (P = .04). Conversely, urinary phenol levels were significantly lower in children 5 years (P = .00). Conclusion Together, these findings reveal that children exposed to benzene experience a range of illness symptoms and an altered profile of urinary phenol indicating their vulnerability to potentially increased health complications.

  15. Identification of enzymes involved in anaerobic benzene degradation by a strictly anaerobic iron-reducing enrichment culture. (United States)

    Abu Laban, Nidal; Selesi, Draženka; Rattei, Thomas; Tischler, Patrick; Meckenstock, Rainer U


    Anaerobic benzene degradation was studied with a highly enriched iron-reducing culture (BF) composed of mainly Peptococcaceae-related Gram-positive microorganisms. The proteomes of benzene-, phenol- and benzoate-grown cells of culture BF were compared by SDS-PAGE. A specific benzene-expressed protein band of 60 kDa, which could not be observed during growth on phenol or benzoate, was subjected to N-terminal sequence analysis. The first 31 amino acids revealed that the protein was encoded by ORF 138 in the shotgun sequenced metagenome of culture BF. ORF 138 showed 43% sequence identity to phenylphosphate carboxylase subunit PpcA of Aromatoleum aromaticum strain EbN1. A LC/ESI-MS/MS-based shotgun proteomic analysis revealed other specifically benzene-expressed proteins with encoding genes located adjacent to ORF 138 on the metagenome. The protein products of ORF 137, ORF 139 and ORF 140 showed sequence identities of 37% to phenylphosphate carboxylase PpcD of A. aromaticum strain EbN1, 56% to benzoate-CoA ligase (BamY) of Geobacter metallireducens and 67% to 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX) of A. aromaticum strain EbN1 respectively. These genes are proposed as constituents of a putative benzene degradation gene cluster (∼ 17 kb) composed of carboxylase-related genes. The identified gene sequences suggest that the initial activation reaction in anaerobic benzene degradation is probably a direct carboxylation of benzene to benzoate catalysed by putative anaerobic benzene carboxylase (Abc). The putative Abc probably consists of several subunits, two of which are encoded by ORFs 137 and 138, and belongs to a family of carboxylases including phenylphosphate carboxylase (Ppc) and 3-octaprenyl-4-hydroxybenzoate carboxy-lyase (UbiD/UbiX).

  16. The treatment of gaseous benzene by two-phase partitioning bioreactors: a high performance alternative to the use of biofilters

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, C.T.; Daugulis, A.J. [Dept. of Chemical Engineering, Queen' s Univ., Kingston, ON (Canada)


    A 2-1 (1-1 working volume) two-phase partitioning bioreactor (TPPB) was used as an integrated scrubber/bioreactor in which the removal and destruction of benzene from a gas stream was achieved by the reactor's organic/aqueous liquid contents. The organic solvent used to trap benzene was n-hexadecane, and degradation of benzene was achieved in the aqueous phase using the bacterium Alcaligenes xylosoxidans Y234. A gas stream with a benzene concentration of 340 mg l{sup -1} at a flow rate of 0.414 l h{sup -1} was delivered to the system at a loading capacity of 140 g m{sup -3} h{sup -1}, and an elimination capacity of 133 g m{sup -3} h{sup -1} was achieved (the volume in this term is the total liquid volume of the TPPB). This elimination capacity is between 3 and 13 times greater than any benzene elimination achieved by biofiltration, a competing biological air treatment strategy. It was also determined that the evaluation of TPPB performance in terms of elimination capacity should include the cell mass present in the system, as this is a readily controllable quantity. A specific benzene utilization rate of 0.57 g benzene (g cells){sup -1} h{sup -1} was experimentally determined in a bioreactor with a cell concentration that varied dynamically between 0.2 and 1 g l{sup -1}. If it assumed that this specific benzene utilization rate (0.57 g g{sup -1} h{sup -1}) is independent of cell concentration, then a TPPB operated at high cell concentrations could potentially achieve elimination capacities several hundred times greater than those obtained with biofilters. (orig.)

  17. Effect of linear alkyl benzene sulfonate in skin of fish fingerlings (Cirrhina mrigala): observations with scanning electron microscope. (United States)

    Misra, V; Chawla, G; Kumar, V; Lal, H; Viswanathan, P N


    Pathomorphological changes in the skin was noticed under the scanning electron microscope in fish fingerlings (Cirrhina mrigala) exposed to 0.005 ppm (25% of the LC50) concentration to linear alkyl benzene sulfonate. The epithelial cells present in the epidermis of the skin were found to secrete more mucus with linear alkyl benzene sulfonate (LAS) than did controls. The presence or deposition of mucus on the surface of skin indicated likely molecular interaction between constituents of mucus and LAS.

  18. Determination of the succinonitrile-benzene and succinonitrile-cyclohexanol phase diagrams by thermal and UV spectroscopic analysis (United States)

    Kaukler, W. F.; Frazier, D. O.; Facemire, B.


    Equilibrium temperature-composition diagrams were determined for the two organic systems, succinonitrile-benzene and succinonitrile-cyclohexanol. Measurements were made using the common thermal analysis methods and UV spectrophotometry. Succinonitrile-benzene monotectic was chosen for its low affinity for water and because UV analysis would be simplified. Succinonitrile-cyclohexanol was chosen because both components are transparent models for metallic solidification, as opposed to the other known succinonitrile-based monotectics.

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

    Directory of Open Access Journals (Sweden)

    Lidong Cao


    Full Text Available The toxic inert ingredients in pesticide formulations are strictly regulated in many countries. In this paper, a simple and efficient headspace-gas chromatography-mass spectrometry (HSGC-MS method using fluorobenzene as an internal standard (IS for rapid simultaneous determination of benzene and toluene in pesticide emulsifiable concentrate (EC was established. The headspace and GC-MS conditions were investigated and developed. A nonpolar fused silica Rtx-5 capillary column (30 m×0.20 mm i.d. and 0.25 μm film thickness with temperature programming was used. Under optimized headspace conditions, equilibration temperature of 120°C, equilibration time of 5 min, and sample size of 50 μL, the regression of the peak area ratios of benzene and toluene to IS on the concentrations of analytes fitted a linear relationship well at the concentration levels ranging from 3.2 g/L to 16.0 g/L. Standard additions of benzene and toluene to blank different matrix solutions 1ead to recoveries of 100.1%–109.5% with a relative standard deviation (RSD of 0.3%–8.1%. The method presented here stands out as simple and easily applicable, which provides a way for the determination of toxic volatile adjuvant in liquid pesticide formulations.

  20. Substrate-mediated enhanced activity of Ru nanoparticles in catalytic hydrogenation of benzene

    KAUST Repository

    Liu, Xin


    The impact of carbon substrate-Ru nanoparticle interactions on benzene and hydrogen adsorption that is directly related to the performance in catalytic hydrogenation of benzene has been investigated by first-principles based calculations. The stability of Ru 13 nanoparticles is enhanced by the defective graphene substrate due to the hybridization between the dsp states of the Ru 13 particle with the sp 2 dangling bonds at the defect sites. The local curvature formed at the interface will also raise the Ru atomic diffusion barrier, and prohibit the particle sintering. The strong interfacial interaction results in the shift of averaged d-band center of the deposited Ru nanoparticle, from -1.41 eV for a freestanding Ru 13 particle, to -1.17 eV for the Ru/Graphene composites, and to -1.54 eV on mesocellular foam carbon. Accordingly, the adsorption energies of benzene are increased from -2.53 eV for the Ru/mesocellular foam carbon composites, to -2.62 eV on freestanding Ru 13 particles, to -2.74 eV on Ru/graphene composites. A similar change in hydrogen adsorption is also observed, and all these can be correlated to the shift of the d-band center of the nanoparticle. Thus, Ru nanoparticles graphene composites are expected to exhibit both high stability and superior catalytic performance in hydrogenation of arenes. © 2012 The Royal Society of Chemistry.

  1. A MEMS-based Benzene Gas Sensor with a Self-heating WO3 Sensing Layer

    Directory of Open Access Journals (Sweden)

    Lung-Ming Fu


    Full Text Available In the study, a MEMS-based benzene gas sensor is presented, consisting of a quartz substrate, a thin-film WO3 sensing layer, an integrated Pt micro-heater, and Pt interdigitated electrodes (IDEs. When benzene is present in the atmosphere, oxidation occurs on the heated WO3 sensing layer. This causes a change in the electrical conductivity of the WO3 film, and hence changes the resistance between the IDEs. The benzene concentration is then computed from the change in the measured resistance. A specific orientation of the WO3 layer is obtained by optimizing the sputtering process parameters. It is found that the sensitivity of the gas sensor is optimized at a working temperature of 300 °C. At the optimal working temperature, the experimental results show that the sensor has a high degree of sensitivity (1.0 KΩ ppm-1, a low detection limit (0.2 ppm and a rapid response time (35 s.

  2. Interactive Effect of Air-Water Ratio and Temperature on the Air Stripping of Benzene

    Directory of Open Access Journals (Sweden)

    M. E. Abdullahi


    Full Text Available High cost of pilot scale studies has led engineers to use simulation to study the factors that affect process performance. This study focuses on the interactive effect of air water ratio and temperature on the removal of volatile organic compounds from polluted water using packed column air stripper taking benzene as a case study. The process governing equations developed based on two-film model of mass transfer were solved using MATLAB and a surface response plot was done. The mass transfer coefficient increased from 0.1237x10-5 to 0.1932x10-5 s-1 as the temperature was raised from 293 to 323 K. Also, the Henry’s constant increased from 228.59 to 883.36 K as the temperature was raised from 293 to 323 K. Benzene removal efficiencies of over 99% were obtained for all combinations of temperature and air-water ratio. The result also indicated that air stripping of benzene from wastewater is most dependent on temperature and moderately on air-water ratio.

  3. Alkylation of benzene using batch and continuous fixed-bed reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria; Buelna Quijada, Genoveva (Universidad Autonoma de Tamaulipas, Tamaulipas, Mexico)


    Alkylation reactions of benzene with propylene using heterogeneous catalysts H{sup +}-{beta} zeolite, MCM-22, and ZSM-5 were studied for their affinity for cumene production. This work focused on the gas-phase reaction using different crystalline catalysts at several temperatures and amounts of reactants using both batch and continuous fixed-bed reactors. The properties of baseline commercial H{sup +}-{beta} catalysts versus versions modified with Ga, La, and Pt were studied. Quantitative analysis of product mixture was performed by gas chromatography. For the batch reactor, {beta}-zeolite produced the highest cumene yield and selectivity of 72% and 92%, respectively, at 225 C. At this temperature, a benzene:propylene dilution of 7:1 molar ratio was the optimum. For the continuous system, cumene production is favored at lower space velocities, higher benzene-to-propylene ratio, and temperatures close to 225 C. Ga modification of the H{sup +}-{beta} zeolite significantly enhanced cumene yield in the continuous fixed-bed reactor at 225 C, from 27% of the unmodified {beta}-zeolite to 36% for the Ga-modified one. The life span of modified {beta}-catalysts was studied in the fixed-bed reactor for the first eight hours of reaction.

  4. The Character of Dual Site Adsorbent on Coal Fly Ash Toward Benzene Adsorption

    Directory of Open Access Journals (Sweden)

    Widi Astuti


    Full Text Available Large quantities of coal fly ash (CFA are produced during combustion of coal in the production of electricity. Most of this ash has not been widely used. CFA is mainly composed of some oxides including Al2O3 and SiO2 having active site and unburnedcarbon as a mesopore that enables it to act as a dual site adsorbent. To get different characters of dual site, CFA was sieved using 150 mesh size, heated at 400oC and reactedwith sodium hydroxide solution. Furthermore, CFA was used as adsorbent of benzene in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded that single site model yielded excellent fit with equilibrium data of benzene. The values of maximum concentration of adsorbate in solid surface (Cμm and Langmuir constant (KL are affected by [Si+Al]/C ratio in CFA. The increase of [Si+Al]/C ratio causes a decrease of qm and KL values.Keywords : coal fly ash, adsorption, benzene

  5. Benzene ground-water exposure study, Nesmith, South Carolina. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stallings, F.L.


    Residents whose private well was contaminated with benzene and other volatile organic compounds (VOCs) were evaluated for VOC exposure. The extent to which they may have ingested contaminated water before discovering that the well was contaminated was not certain. However, they reported continuing to use water obtained from the well for bathing and household sanitation purposes after becoming aware of its contamination. Each adult household member completed a survey questionnaire to quantify individual water usage and characterize other potential exposure sources for VOCs. Although results of blood measurements for benzene for three family members showed blood levels of benzene that were within the range found in the third National Health and Nutrition Examination Survey (NHANES III) results, Blood levels for two of the family members were above the 90th percentile value for the reference population. Trichloroethene was not a suspected contaminant, but blood specimens of three study participants showed elevations in the upper 10 percent of the NHANES III population range. Two of the participants gave an occupational history consistent with an exposure potential to these analytes.

  6. Reaction Kinetics of Ozonation of Trichloroethylene and Benzene in Gas and Liquid Phase

    Institute of Scientific and Technical Information of China (English)


    The kinetics of ozonation reactions oftrichloroethylene (TCE) and benzene in gas and liquid phases at101.3 kPa and 298 K was investigated in this paper. The ozonation ofTCE is first order with respect to the ozone concentration and one andhalf order to TCE in the gas phase with the average rate constant 57.30(mol*L-1)-1.5 *s-1, and the TCE ozonation inaqueous medium is first order with respect to both ozone andtrichloroethylene with the average rate constant 6.30(mol*L-1)-1 *s-1. The ozonation of benzene inthe gas phase is first order in ozone but independent of the benzeneconcentration with the average reaction rate constant 0.0011 s-1.The overall kinetics of reaction between ozone and benzene in aqueoussolution is found to be first order with one-half order in both ozoneand bezene, with the average reaction rate constant 2.67 s-1. Itis found that the ozonation rate of pallutants is much quicker than that ofself-decomposition of ozone in both gas and aqueous phase.

  7. Low level detection of Benzene in Food Grade Hexane by Ultraviolet Spectrophotometry. (United States)

    Emmandi, R; Sastry, M I S; Patel, M B


    A simple, sensitive, and accurate Ultraviolet Spectrophotometric method has been developed and validated for the determination of Benzene in Food Grade Hexane. Benzene in spectroscopic grade Hexane shows vibrational fine structure having four well resolved peaks. In the wavelength range 240-270nm, peak at 255nm is considered for the method development. Beer's law was obeyed in the concentration range of 0.6-10.0μLL(-1), with correlation coefficient, 0.9999, detection limit 0.2μLL(-1) and quantitation limit 0.6μLL(-1) are established. Percentage recovery studies showed that the method was not affected by the presence of other solvents having the similar boiling range with Hexane. The method was validated by determining its accuracy and precision which proves suitability of the developed method for the routine determination of Benzene in Food Grade Hexane. The proposed method has been applied successfully for the analysis of the Food Grade Hexane.

  8. Decomposition of multilayer benzene and n-hexane films on vanadium. (United States)

    Souda, Ryutaro


    Reactions of multilayer hydrocarbon films with a polycrystalline V substrate have been investigated using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. Most of the benzene molecules were dissociated on V, as evidenced by the strong depression in the thermal desorption yields of physisorbed species at 150 K. The reaction products dehydrogenated gradually after the multilayer film disappeared from the surface. Large amount of oxygen was needed to passivate the benzene decomposition on V. These behaviors indicate that the subsurface sites of V play a role in multilayer benzene decomposition. Decomposition of the n-hexane multilayer films is manifested by the desorption of methane at 105 K and gradual hydrogen desorption starting at this temperature, indicating that C-C bond scission precedes C-H bond cleavage. The n-hexane dissociation temperature is considerably lower than the thermal desorption temperature of the physisorbed species (140 K). The n-hexane multilayer morphology changes at the decomposition temperature, suggesting that a liquid-like phase formed after crystallization plays a role in the low-temperature decomposition of n-hexane.

  9. Use of piperylene additive in purificaton of a benzene-toluene-xylene fraction

    Energy Technology Data Exchange (ETDEWEB)

    Kulyasova, S.V.; Mikhno, S.I.; Kolyandr, L.Ya.


    The use of additives gives the process of sulfuric acid purification of crude benzene-toluene-xylene (BTX) fraction a certain degree of specificity: the unsaturated compounds of the additives alkylate not only the thiophene, but also the benzene hydrocarbons; they polymerize, and may even copolymerize with unsaturated compounds of the fraction. The predominance of one of these processes is determined by the amount of the additive, the conditions of its injection, and the composition of the fraction. Thus the use of additives requires development of special conditions for the entire washing process. The main problems are the ideal composition of the fraction, the conditions of injection of the additive, the efficiency of the individual purification stages and the duration of the stages and the process as a whole. In spite of the obvious advantages of purification of the BT fraction (preservation of resources of benzene hydrocarbons, styrene and other tar-forming compounds), purification of the BTX fraction is presently used, since the BT fraction is practically impossible to obtain without reconstruction of the existing rectification plants. Since the BTX fraction always contains unsaturated compounds the injection of the additive should be preceded by removal of the thiophene by the unsaturated compounds of the fraction. Laboratory investigations were conducted to develop the technology.

  10. Potential application of an Aspergillus strain in a pilot biofilter for benzene biodegradation (United States)

    Sun, Da; Zhang, Kun; Duan, Chuanren; Wu, Wei; Deng, Daiyong; Yu, Donghong; Shahzad, M. Babar; Xu, Dake; Tang, Ju; Luo, Li; Chen, Jia; Wang, Jinxuan; Chen, Yidan; Xie, Xiang; Wang, Guixue


    A biofilter with fungus was developed for efficient degradation of benzene, which can overcome the potential risk of leakage commonly found in such services. Results indicated that the optimum parameter values were temperature 40 °C, pH 6, and 500 mg L−1 of the initial benzene concentration. Besides, the empty bed residence time and inlet load range of biofilter were set to 20 s and 21.23–169.84 g m−3 h−1 respectively. Under these conditions, this biofilter can obtain the maximum removal efficiency of more than 90%, the eliminating capacity could be up to 151.67 g m−3 h−1. Furthermore, scanning electron microscopy was used to investigate three filler materials for packing fungus biofilm. This is the first study introducing an Aspergillus strain for benzene removal and these results highlight that the development of this biofilter has the potential scaling-up application as gas-processing of industrial wastes. PMID:28383064

  11. Toward in Situ Measurement of the Density of Liquid Benzene Using Optical Kerr Effect Spectroscopy. (United States)

    Bender, John S; Cohen, Samuel R; He, Xiaoxiao; Fourkas, John T; Coasne, Benoit


    The high-frequency portion of the optical Kerr effect (OKE) spectrum of benzene shifts to higher frequency with decreasing temperature at constant pressure. This behavior has been interpreted previously in terms of an increase in librational frequencies due to the decrease in free volume with liquid densification. However, decreasing temperature also provides less access to the more repulsive portion of the intermolecular potential, which would cause the blue edge of the spectrum to red-shift. To explore the relative importance of these phenomena, molecular dynamics simulations of benzene are used to isolate the effects of temperature and density on the spectrum. The simulations show that, at constant density, the high-frequency portion of the spectrum shifts to lower frequency with decreasing temperature. In contrast, at constant temperature, the high-frequency portion of the spectrum shifts to higher frequency with increasing density. These results indicate that density plays a greater role in determining the position of the blue edge of the low-frequency Raman spectrum of benzene than does temperature. Empirical fits show that the effects of changing density or temperature are similar in experimental and simulated OKE spectra. Furthermore, line-shape analysis of simulated spectra under isochoric and isothermal conditions shows that the effects of density and temperature are separable, suggesting that OKE spectroscopy is a viable technique for in situ measurement of the density of van der Waals liquids.

  12. Phase equilibria in ionic liquid-aromatic compound mixtures, including benzene fluorination effects. (United States)

    Blesic, Marijana; Lopes, José N Canongia; Pádua, Agílio A H; Shimizu, Karina; Gomes, Margarida F Costa; Rebelo, Luís Paulo N


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

  13. Extracting conformational structure information of benzene molecules via laser-induced electron diffraction

    Directory of Open Access Journals (Sweden)

    Yuta Ito


    Full Text Available We have measured the angular distributions of high energy photoelectrons of benzene molecules generated by intense infrared femtosecond laser pulses. These electrons arise from the elastic collisions between the benzene ions with the previously tunnel-ionized electrons that have been driven back by the laser field. Theory shows that laser-free elastic differential cross sections (DCSs can be extracted from these photoelectrons, and the DCS can be used to retrieve the bond lengths of gas-phase molecules similar to the conventional electron diffraction method. From our experimental results, we have obtained the C-C and C-H bond lengths of benzene with a spatial resolution of about 10 pm. Our results demonstrate that laser induced electron diffraction (LIED experiments can be carried out with the present-day ultrafast intense lasers already. Looking ahead, with aligned or oriented molecules, more complete spatial information of the molecule can be obtained from LIED, and applying LIED to probe photo-excited molecules, a “molecular movie” of the dynamic system may be created with sub-Ångström spatial and few-ten femtosecond temporal resolutions.

  14. σ-Aromaticity in hexa-group 16 atom-substituted benzene dications: a theoretical study. (United States)

    Hatanaka, Miho; Saito, Masaichi; Fujita, Masahiro; Morokuma, Keiji


    C6I6(2+) has been reported to have a σ-aromatic character since removal of two σ anti-bonding electrons localized on iodines results in fulfilling Hückel (4n+2) rules for I6(2+) as well as C6 parts. To search for molecules possessing similar character, hexa-group 16 atom-substituted benzene dications C6(ChH)6(2+) (Ch = S, Se, Te) and their derivatives are examined for aromatic character by using nucleus-independent chemical shift (NICS). For these dications, in which iodines in C6I6(2+) are replaced by group 16 atoms, negative NICS values larger in magnitude than for benzene are found when a σ anti-bonding orbital localized on group 16 atoms is unoccupied. To clarify the origin of large negative NICS values, they are decomposed into individual molecular orbitals. It has been shown that both π bonding orbitals on C6 and σ bonding orbitals on Se6 or Te6 contribute to the negative NICS values, indicating that the aromaticity of these dications have a substantial σ character as well as π characters. Aromaticity of group 14 and 15 atom-substituted benzene dications is also discussed.

  15. Benzene exposure among auto-repair workers from workplace ambience: A pioneer study from Pakistan

    Directory of Open Access Journals (Sweden)

    Atif Kamal


    Full Text Available Objectives: In Pakistan, the reports on benzene exposure among workers in chemical industries are almost non-existing due to limited research work in the field of exposure science. This study aimed to investigate such exposure in a widely adopted occupation in Rawalpindi city. Material and Methods: In this cross-sectional study, 60 blood samples (N = 20/group of mechanics (MCs, spray painters (PNs and control participants (CN were analyzed. The socio-economic and demographic information of workers and that of workplaces was documented using a short questionnaire. Results: We identified that the workers in spray-painting occupation are highly at risk of benzene exposure. The results showed that PNs were more at risk of exposure to benzene than MCs, and this exposure was significantly correlated with long working hours (r = 0.68, p < 0.001. Moreover, there are several limitations in workplace setups, which need to be addressed in order to mitigate workers health risk in this occupation. In addition to the reckless use of chemicals, other identified predictors of exposure included active and passive smoking, poor workplace hygiene and substandard ventilation. Conclusions: To mitigate workplace exposure, it is necessary to reduce working hours and encourage regular use of self-protective equipments and adoption of proper hygiene in chemical workplaces.

  16. Induction of micronuclei and aneuploidy by the quinone-forming agents benzene and o-phenylphenol. (United States)

    Eastmond, D A


    A number of carcinogens appear to exert their tumorigenic effects through the formation of quinone metabolites. These quinone-forming carcinogens are generally inactive or weakly active in standard gene mutation assays. Accumulating evidence indicates that this class of compounds may exert their genotoxic and carcinogenic effects through the induction of large-scale gene alterations. This article presents an overview of work that has been performed using recently developed molecular cytogenic techniques to investigate the aneuploidy-inducing and clastogenic properties of the major quinone-forming metabolites of benzene, a widely used industrial chemical, and o-phenylphenol, a fungicide and disinfectant. These metabolites of benzene (hydroquinone, catechol, and benzenetriol) and o-phenylphenol (phenylhydroquinone) have each been shown to be capable of interfering with chromosome segregation and inducing chromosomal breakage. These results indicate that both numerical and structural chromosomal aberrations induced by the quinone metabolites of benzene and o-phenylphenol may play a role in the carcinogenic effects of these two agents.

  17. [Effect of metals, benzene, pesticides and ethylene oxide on the haematopoietic system]. (United States)

    Pyszel, Angelika; Wróbel, Tomasz; Szuba, Andrzej; Andrzejak, Ryszard


    The hematopoietic system, due to intensive cells proliferation, is very sensitive to toxic substances. Many chemicals, including benzene, pesticides (dithiocarbamines), ethylene oxide and metals (mercury, cadmium, chrome, cobalt, lead, aluminum) exert their toxic effect on the hematopoietic system. Exposure to each of these substances may occur in the work place due to environmental pollution and in municipal or residential areas. Exposure to lead, aluminum, cadmium, and benzene results in the incidence of anemia. In addition, exposure to benzene and its metabolites leads to myelodysplastic syndromes, leukemia, lymphomas and bone marrow aplasia. Ethylene oxide induces neoplasm of the hematopoietic system and lymphomas, especially non-Hodgkin lymphoma. Arsenic compounds act like immunosuppressants. Mercury and chrome affect the immune system by immunosuppression and by evoking autoimmune reactions. Dithiocarbamates are suspected to induce leukemia. An analysis of the pathophysiology of individual substances reveal universal toxic mechanisms. In this paper, the authors discuss the pathomechanism of toxic effects of the aforesaid chemicals on the haematopoietic system and peripheral blood cells from the viewpoint of mutagenesis, apoptosis, myelotoxicity, anemia, immunomodulation, and individual sensitivity.

  18. Fate of the Benzene Ring of Linear Alkylbenzene Sulfonate in Natural Waters (United States)

    Larson, R. J.; Payne, A. G.


    The biodegradability of linear alkylbenzene sulfonate (LAS) was studied in water samples collected from a receiving stream at locations above and below the discharge of a municipal wastewater treatment plant. Rates of primary biodegradation were determined for a commercial LAS mixture by a modified methylene blue-active substance method. Rates of LAS ultimate degradation were determined by radiochemical methods, using a C12 LAS homolog uniformly labeled with 14C in the benzene ring. The C12 LAS was tested at low concentrations (50 and 500 μg/liter) comparable to those existing in the receiving stream. Loss of methylene blue-active substance response over time occurred rapidly in water samples containing sediment collected from below the treatment plant, with an estimated half-life for LAS of 0.23 days. Evolution of 14CO2 during mineralization of the benzene ring occurred rapidly in the same samples, with a half-life for the benzene ring of 0.73 day. Mineralization of the benezene ring was also observed in river water containing no sediments and in river water and sediment samples collected from above the treatment plant. However, the rate of degradation was reduced in these cases, with half-lives for ring carbon ranging from 1.4 to 14 days. Although LAS degradation was enhanced in the presence of sediments, adsorption of LAS to the clay-silt fraction of river sediments was low, and most of the radioactivity was bound to biomass. PMID:16345731

  19. Survey the Efficiency of Catalytic Ozonation Process with Carbosieve in the Removal of Benzene from Polluted Air Stream

    Directory of Open Access Journals (Sweden)

    M. Samarghandi


    Full Text Available Introduction & Objective: Benzene is one of the most common volatile organic compounds in the indoor and outdoor environments that has always been considered as one of the causes of air pollution. Thus before being discharged to the environment, it must be treated from pol-luted air stream. The aim of this study was to determine the efficiency of catalytic ozonation process with carbosieve in the removal of benzene from polluted air stream. Materials & Methods: The study was experimental in which catalytic ozonation process with carbosieve was used in the removal of benzene from polluted air stream. The experiments were carried out in a reactor with continuous system and the results of catalytic ozonation were compared with the results of single ozonation and carbosieve adsorbent .The sampling, benzene analyzing and determining of ozone concentration in samples were done with 1501 NMAM method by GC equipped with FID detector and iodometry , respectively. Results: The results of this study showed that the removal effectiveness of single ozonation process is averagely less than 19%. Also the efficiency of absorbent decreased with the con-centration increase of benzene.The increase ratio of efficiency in catalytic ozonation process to efficiency of carbosieve adsorbent was averagely 45%. Conclusion: With regard to high efficiency of catalytic ozonation process and increasing the benzene removal , the catalytic ozonation process is suggested as a promising and alternative technology for elimination of VOCs from the polluted air stream. (Sci J Hamadan Univ Med Sci 2014; 20 (4:303-311

  20. Evaluating the impact of ambient benzene vapor concentrations on product water from Condensation Water From Air technology. (United States)

    Kinder, Katherine M; Gellasch, Christopher A; Dusenbury, James S; Timmes, Thomas C; Hughes, Thomas M


    Globally, drinking water resources are diminishing in both quantity and quality. This situation has renewed interest in Condensation Water From Air (CWFA) technology, which utilizes water vapor in the air to produce water for both potable and non-potable purposes. However, there are currently insufficient data available to determine the relationship between air contaminants and the rate at which they are transferred from the air into CWFA untreated product water. This study implemented a novel experimental method utilizing an environmental test chamber to evaluate how air quality and temperature affects CWFA untreated product water quality in order to collect data that will inform the type of water treatment required to protect human health. This study found that temperature and benzene air concentration affected the untreated product water from a CWFA system. Benzene vapor concentrations representing a polluted outdoor environment resulted in benzene product water concentrations between 15% and 23% of the USEPA drinking water limit of 5μg/l. In contrast, product water benzene concentrations representing an indoor industrial environment were between 1.4 and 2.4 times higher than the drinking water limit. Lower condenser coil temperatures were correlated with an increased concentration of benzene in the product water. Environmental health professionals and engineers can integrate the results of this assessment to predict benzene concentrations in the product water and take appropriate health protective measures.

  1. Predicting the Strength of Anion-π Interactions of Substituted Benzenes: the Development of Anion-π Binding Substituent Constants. (United States)

    Bagwill, Christina; Anderson, Christa; Sullivan, Elizabeth; Manohara, Varun; Murthy, Prithvi; Kirkpatrick, Charles C; Stalcup, Apryll; Lewis, Michael


    A computational study aimed at accurately predicting the strength of the anion-π binding of substituted benzenes is presented. The anion-π binding energies (Ebind) of 37 substituted benzenes and the parent benzene, with chloride or bromide were investigated at the MP2(full)/6-311++G** level of theory. In addition, energy decomposition analysis was performed on 27 selected chloride-arene complexes via symmetry adapted perturbation theory (SAPT), using the SAPT2+ approach. Initial efforts aimed to correlate the anion-π Ebind values with the sum of the Hammett constants σp (Σσp) or σm (Σσm), as done by others. This proved a decent approach for predicting the binding strength of aromatics with electron-withdrawing substituents. For the Cl(-)-substituted benzene Ebind values, the correlation with the Σσp and Σσm values of aromatics with electron-withdrawing groups had r(2) values of 0.89 and 0.87 respectively. For the Br(-)-substituted benzene Ebind values, the correlation with the Σσp and Σσm values of aromatics with electron-withdrawing groups had r(2) values of 0.90 and 0.87. However, adding aromatics with electron-donating substituents to the investigation caused the correlation to deteriorate. For the Cl(-)-substituted benzene complexes the correlation between Ebind values and the Hammett constants had r(2) = 0.81 for Σσp and r(2) = 0.84 for Σσm. For the Br(-)-substituted benzene complexes, the respective r(2) values were 0.71 for Σσp and 0.79 for Σσm. The deterioration in correlation upon consideration of substituted benzenes with electron-donating substituents is due to the anion-π binding energies becoming more attractive regardless of what type of substituent is added to the aromatic. A similar trend has been reported for parallel face-to-face substituted benzene-benzene binding. This is certainly counter to what electrostatic arguments would predict for trends in anion-π binding energies, and this discrepancy is further highlighted

  2. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane (United States)

    Adebajo, Moses O.; Long, Mervyn A.; Frost, Ray L.


    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  3. From hexaoxy-[6]pericyclynes to carbo-cyclohexadienes, carbo-benzenes, and dihydro-carbo-benzenes: synthesis, structure, and chromophoric and redox properties. (United States)

    Leroyer, Léo; Lepetit, Christine; Rives, Arnaud; Maraval, Valérie; Saffon-Merceron, Nathalie; Kandaskalov, Dmytro; Kieffer, David; Chauvin, Remi


    When targeting the quadrupolar p-dianisyltetraphenyl-carbo-benzene by reductive treatment of a hexaoxy-[6]pericyclyne precursor 3 with SnCl(2)/HCl, a strict control of the conditions allowed for the isolation of three C(18)-macrocyclic products: the targeted aromatic carbo-benzene 1, a sub-reduced non-aromatic carbo-cyclohexadiene 4A, and an over-reduced aromatic dihydro-carbo-benzene 5A. Each of them was fully characterized by its absorption and NMR spectra, which were interpreted by comparison with calculated spectra from static structures optimized at the DFT level. According to the nucleus-independent chemical shift (NICS) value (NICS≈-13 ppm), the macrocyclic aromaticity of 5A is indicated to be equivalent to that of 1. This is confirmed by the strong NMR spectroscopic deshielding of the ortho-CH protons of the aryl substituents, but also by the strong shielding of the internal proton of the endocyclic trans-CH=CH double bond that results from the hydrogenation of one of the C≡C bonds of 3. Both the aromatics 1 and 5A exhibit a high crystallinity, revealed by SEM and TEM images, which allowed for a structural determination by using an X-ray microsource. A good agreement with calculated molecular structures was found, and columnar assemblies of the C(18) macrocycles were evidenced in the crystal packing. The non-aromatic carbo-cyclohexadiene 4A is shown to be an intermediate in the formation of 1 from 3. It exhibits a remarkable dichromism in solution, which is related to the occurrence of two intense bands in the visible region of its UV/Vis spectrum. These properties could be attributed to the dibutatrienylacetylene (DBA) unit that occurs in the three chromophores, but which is not involved in a macrocyclic π-delocalization in 4A only. A versatile redox behavior of the carbo-chromophores is evidenced by cyclic voltammetry and was analyzed by calculation of the ionization potential, electron affinity, and frontier molecular orbitals.

  4. Degradation of Benzene by Pseudomonas veronii 1YdBTEX2 and 1YB2 Is Catalyzed by Enzymes Encoded in Distinct Catabolism Gene Clusters (United States)

    de Lima-Morales, Daiana; Chaves-Moreno, Diego; Wos-Oxley, Melissa L.; Jáuregui, Ruy; Vilchez-Vargas, Ramiro


    Pseudomonas veronii 1YdBTEX2, a benzene and toluene degrader, and Pseudomonas veronii 1YB2, a benzene degrader, have previously been shown to be key players in a benzene-contaminated site. These strains harbor unique catabolic pathways for the degradation of benzene comprising a gene cluster encoding an isopropylbenzene dioxygenase where genes encoding downstream enzymes were interrupted by stop codons. Extradiol dioxygenases were recruited from gene clusters comprising genes encoding a 2-hydroxymuconic semialdehyde dehydrogenase necessary for benzene degradation but typically absent from isopropylbenzene dioxygenase-encoding gene clusters. The benzene dihydrodiol dehydrogenase-encoding gene was not clustered with any other aromatic degradation genes, and the encoded protein was only distantly related to dehydrogenases of aromatic degradation pathways. The involvement of the different gene clusters in the degradation pathways was suggested by real-time quantitative reverse transcription PCR. PMID:26475106

  5. Identification of 6-hydroxy-trans,trans-2,4-hexadienoic acid, a novel ring-opened urinary metabolite of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Kline, S.A.; Robertson, J.F.; Grotz, V.L.; Goldstein, B.D.; Witz, G. (Robert Wood Johnson Medical School, Piscataway, NJ (United States) Environmental and Occupational Health Sciences Institute, Piscataway, NJ (United States))


    The authors have studied the in vivo metabolism of benzene in mice to ring-opened compounds excreted in urine. Male CD-1 mice were treated intraperitoneally with benzene (110-440 mg/kg), [[sup 14]C] benzene (220 mg/kg) or trans,trans-muconaldehyde (MUC; 4 mg/kg), a microsomal, hematotoxic metabolite of benzene. Urine, collected over 24 hr, was extracted and analyzed by HPLC with a diode-array detector and by scintillation counting. In addition to trans,trans-muconic acid, previously the only known ring-opened urinary benzene metabolite, a new metabolite, 6-hydroxy-trans,trans-2,4-hexadienoic acid, was detected in urine of mice treated with either benzene or MUC. The authors identified the new metabolite based on coelution of metabolites and UV spectral comparison with authentic standards in unmethylated and methylated urine extracts. Results presented here are consistent with the intermediacy of the ring-opened metabolites.

  6. Lack of sensitivity of urinary trans,trans-muconic acid in determining low-level (ppb) benzene exposure in children. (United States)

    Barbieri, Anna; Accorsi, Antonio; Raffi, Giovanni Battista; Nicoli, Luciana; Violante, Francesco Saverio


    Benzene is a widespread pollutant of which the main source in the outside environment is automotive traffic. Benzene is also present in cigarette smoke, and small quantities exist in drinking water and food; all of these sources contribute to pollution of indoor environments. Benzene exposure may be studied with biologic indicators. In the present study, the authors evaluated whether differences in urinary concentrations of trans,transmuconic acid (t,t-MA) were detectable in a sample of 150 children and if the chemical was correlated with environmental exposures to low levels of benzene. The children attended primary schools that had significantly different-but low-environmental benzene levels. Analysis of urinary t,t-MA was achieved with high-performance liquid chromatography (photodiode array detector), and analysis of passive air samplers for benzene was performed with gas chromatography-mass spectrometry. Statistical analysis (Kruskal-Wallis test) indicated that differences in urinary levels of t,t-MA in children from urban and rural areas were not statistically significant (p = .07), nor were there significant differences between children with and without relatives who smoked (p = .69). As has been shown in other studies of children and adults, results of our study evidenced (1) the difficulty of correlating concentrations of urinary biomarkers with environmental exposure to benzene at a parts-per-billion level (i.e., traffic and environmental tobacco smoke) and, consequently, (2) the lack of specificity of t,t-MA as a biological indicator for the study of a population's exposure.

  7. Using 13C-labeled benzene and Raman gas spectroscopy to investigate respiration and biodegradation kinetics following soil contamination (United States)

    Jochum, Tobias; Popp, Juergen; Frosch, Torsten


    Soil and groundwater contamination with benzene can cause serious environmental damages. However, many soil microorganisms are capable to adapt and known to strongly control the fate of organic contamination. Cavity enhanced Raman gas spectroscopy (CERS) was applied to investigate the short-term response of indigenous soil bacteria to a sudden surface contamination with benzene regarding the temporal variations of gas products and their exchange rates with the adjacent atmosphere. 13C-labeled benzene was spiked on a silty-loamy soil column (sampled from Hainich National Park, Germany) in order to track and separate the changes in heterotrophic soil respiration - involving 12CO2 and O2 - from the microbial process of benzene degradation, which ultimately forms 13CO2.1 The respiratory quotient (RQ) of 0.98 decreased significantly after the spiking and increased again within 33 hours to a value of 0.72. This coincided with maximum 13CO2 concentration rates (0.63 μ mol m-2 s-1), indicating highest benzene degradation at 33 hours after the spiking event. The diffusion of benzene in the headspace and the biodegradation into 13CO2 were simultaneously monitored and 12 days after the benzene spiking no measurable degradation was detected anymore.1 The RQ finally returned to a value of 0.96 demonstrating the reestablished aerobic respiration. In summary, this study shows the potential of combining Raman gas spectroscopy and stable isotopes to follow soil microbial biodegradation dynamics while simultaneously monitoring the underlying respiration behavior. Support by the Collaborative Research Center 1076 Aqua Diva is kindly acknowledged. We thank Beate Michalzik for soil analysis and discussion. 1. T. Jochum, B. Michalzik, A. Bachmann, J. Popp and T. Frosch, Analyst, 2015, 140, 3143-3149.

  8. Integration of coal pyrolysis process with iron ore reduction:Reduction behaviors of iron ore with benzene-containing coal pyrolysis gas as a reducing agent☆

    Institute of Scientific and Technical Information of China (English)

    Xin Li; Helong Hui; Songgeng Li; Lu He; Lijie Cui


    An integrated coal pyrolysis process with iron ore reduction is proposed in this article. As the first step, iron oxide reduction is studied in a fixed bed reactor using simulated coal pyrolysis gas with benzene as a model tar com-pound. Variables such as reduction temperature, reduction time and benzene concentration are studied. The car-bon deposition of benzene results in the retarded iron reduction at low temperatures. At high temperatures over 800 °C, the presence of benzene in the gas can promote iron reduction. The metallization can reach up to 99%in 20 min at 900 °C in the presence of benzene. Significant increases of hydrogen and CO/CO2 ratio are observed in the gas. It is indicated that iron reduction is accompanied by the reforming and decomposition of benzene. The degree of metal ization and reduction increases with the increasing benzene concentration. Iron oxide can nearly completely be converted into cementite with benzene present in the gas under the experimental conditions. No sintering is found in the reduced sample with benzene in the gas.

  9. Comparative Study on Single-Molecule Junctions of Alkane- and Benzene-Based Molecules with Carboxylic Acid/Aldehyde as the Anchoring Groups (United States)

    Chen, Fang; Peng, Lin-Lu; Hong, Ze-Wen; Mao, Jin-Chuan; Zheng, Ju-Fang; Shao, Yong; Niu, Zhen-Jiang; Zhou, Xiao-Shun


    We have measured the alkane and benzene-based molecules with aldehyde and carboxylic acid as anchoring groups by using the electrochemical jump-to-contact scanning tunneling microscopy break junction (ECSTM-BJ) approach. The results show that molecule with benzene backbone has better peak shape and intensity than those with alkane backbone. Typically, high junction formation probability for same anchoring group (aldehyde and carboxylic acid) with benzene backbone is found, which contributes to the stronger attractive interaction between Cu and molecules with benzene backbone. The present work shows the import role of backbone in junction, which can guide the design molecule to form effective junction for studying molecular electronics.

  10. Benzene Exposure Alters Expression of Enzymes Involved in Fatty Acid β-Oxidation in Male C3H/He Mice

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    Rongli Sun


    Full Text Available Benzene is a well-known hematotoxic carcinogen that can cause leukemia and a variety of blood disorders. Our previous study indicated that benzene disturbs levels of metabolites in the fatty acid β-oxidation (FAO pathway, which is crucial for the maintenance and function of hematopoietic and leukemic cells. The present research aims to investigate the effects of benzene on changes in the expression of key enzymes in the FAO pathway in male C3H/He mice. Results showed that benzene exposure caused reduced peripheral white blood cell (WBC, red blood cell (RBC, platelet (Pit counts, and hemoglobin (Hgb concentration. Investigation of the effects of benzene on the expression of FA transport- and β-oxidation-related enzymes showed that expression of proteins Cpt1a, Crat, Acaa2, Aldh1l2, Acadvl, Crot, Echs1, and Hadha was significantly increased. The ATP levels and mitochondrial membrane potential decreased in mice exposed to benzene. Meanwhile, reactive oxygen species (ROS, hydrogen peroxide (H2O2, and malondialdehyde (MDA levels were significantly increased in the benzene group. Our results indicate that benzene induces increased expression of FA transport and β-oxidation enzymes, mitochondrial dysfunction, and oxidative stress, which may play a role in benzene-induced hematotoxicity.

  11. Measures to evaluate heteroaromaticity and their limitations: Story of skeletally substituted benzenes

    Indian Academy of Sciences (India)

    U Deva Priyakumar; G Narahari Sastry


    Ab initio HF, MP2, CCSD(T) and hybrid density functional B3LYP calculations were performed on a series of skeletally mono- and di-substituted benzenes, (CH)5Z and (CH)4Z2, Z = C-, N, O+, Si-, P, S+, Ge-, As, Se+, BH-, NH+, AlH-, SiH, PH+, GaH-, GeH and AsH+. Various measures of aromaticity such as the bond length equalization, homodesmic equations, singlet-triplet energy difference (DE-), chemical hardness () and out-of-plane distortive tendency are critically analysed. The relative energy ordering in skeletally disubstituted benzenes displays trends that are inexplicable based on conventional wisdom. In general, the orthoisomer is found to be the least stable when the substituent is from the second row, whereas if the substituent is from the fourth row, the ortho-isomer is the most stable. Various qualitative arguments, including (a) lone pair-lone pair repulsion, (b) the sum of bond strengths in the twin Kekule forms, and (c) the rule of topological charge stabilization (TCS), are used to explain the observed relative energy trends. The rule of TCS in conjunction with the sum of bond strengths is found to predict the relative energy ordering reasonably well. The reactivity of this class of compounds is assessed based on their singlet-triplet energy differences, chemical hardness and the frequencies corresponding to out-of-plane skeletal distortions. These reactivity indices show less kinetic stability for the compounds with substituents from the fourth row and point to the fact that the thermodynamically most stable compounds need not be the least reactive ones. The - values indicate that the -framework of benzene weakens upon skeletal substitutions.

  12. On the mechanism of the dehydroaromatization of hexane to benzene by an iridium pincer catalyst. (United States)

    Thawani, Akanksha; Rajeev, Ramanan; Sunoj, Raghavan B


    The developments in the area of transition-metal pincer complexes have opened up new avenues for conversion of saturated hydrocarbons to more useful aromatic compounds under homogeneous reaction conditions. In the backdrop of an interesting series of conversions of unbranched alkanes to benzene, toluene, and xylene (known as the BTX family aromatics) reported by Goldman and co-workers (Nature Chem. 2011, 3, 167), we herein present a comprehensive mechanistic picture obtained by using density functional computations. The reaction involves an iridium-PCP-pincer-catalyzed dehydroaromatization of hexane to benzene (in which PCP=η(3) -C6 H3 (iPrP)2 -1,3) by using tert-butylethylene (TBE) as a sacrificial acceptor. The most energetically preferred pathway for a sequence of dehydrogenations is identified to begin with a terminal CH bond activation of n-hexane leading to the formation of hex-1-ene. Although the initial dehydrogenation of n-hexane was found to be endergonic, the accompanying exoergic hydrogenation of TBE to tert-butylethane (TBA) compensates the energetics to keep the catalytic cycle efficient. Subsequent dehydrogenations provide a hexa-1,3-diene and then a hexa-1,3,5-triene. The pincer bound triene is identified to undergo cyclization to furnish cyclohexadiene. Eventually, dehydrogenation of cyclohexa-1,3-diene offers benzene. In the most preferred pathway, the Gibbs free energy barrier for cyclization leading to the formation of cyclohexa-1,3-diene is found to exhibit the highest barrier (21.7 kcal mol(-1) ).

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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).

  14. Atomistic simulation of solid-liquid coexistence for molecular systems: application to triazole and benzene. (United States)

    Eike, David M; Maginn, Edward J


    A method recently developed to rigorously determine solid-liquid equilibrium using a free-energy-based analysis has been extended to analyze multiatom molecular systems. This method is based on using a pseudosupercritical transformation path to reversibly transform between solid and liquid phases. Integration along this path yields the free energy difference at a single state point, which can then be used to determine the free energy difference as a function of temperature and therefore locate the coexistence temperature at a fixed pressure. The primary extension reported here is the introduction of an external potential field capable of inducing center of mass order along with secondary orientational order for molecules. The method is used to calculate the melting point of 1-H-1,2,4-triazole and benzene. Despite the fact that the triazole model gives accurate bulk densities for the liquid and crystal phases, it is found to do a poor job of reproducing the experimental crystal structure and heat of fusion. Consequently, it yields a melting point that is 100 K lower than the experimental value. On the other hand, the benzene model has been parametrized extensively to match a wide range of properties and yields a melting point that is only 20 K lower than the experimental value. Previous work in which a simple "direct heating" method was used actually found that the melting point of the benzene model was 50 K higher than the experimental value. This demonstrates the importance of using proper free energy methods to compute phase behavior. It also shows that the melting point is a very sensitive measure of force field quality that should be considered in parametrization efforts. The method described here provides a relatively simple approach for computing melting points of molecular systems.

  15. Pt-Rh/g Al2O3 Benzene Hydrogenation Reaction as a Characterization Technique

    Directory of Open Access Journals (Sweden)

    Fonseca N.M. da


    Full Text Available Pt-Rh/Al2O3 catalysts prepared by successive incipient impregnations and coimpregnation were characterized by H2 chemisorption, temperature programmed reduction and benzene hydrogenation reaction in the vapor phase. The results showed that Rh plays the role of Pt reducting agent, which is very different from the effects of metal-metal interaction which appear mainly in solids with the highest metal contents. The most important parameter that results in bimetallic particles in the catalyst prepared by successive impregnation is the sequence of metal addition.

  16. Theoretical Study on the Vibrational Spectra and Thermodynamic Properties for Nitro Derivatives of Benzene and Anilines

    Institute of Scientific and Technical Information of China (English)

    WANG Gui-Xiang; GONG Xue-Dong; XIAO He-Ming


    Nitro derivatives of benzene and anilines were optimized to obtain their molecular geometries and electronic structures at a DFT-B3LYP/6-31G* level. Their IR spectra were obtained and assigned by vibrational analysis. Comparing the calculated IR spectra with these of experiments known, all the IR data obtained in this paper were considered to be reliable. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were linearly related with the number of nitro and amino groups as well as the temperature, obviously showing good group additivity.

  17. A Topological Approach to the Correlation of Standard Formation Enthalpy with Path Index of Benzenes Derivatives

    Institute of Scientific and Technical Information of China (English)

    LiLiang-chao; NiCai-hua; LinQiu-yue


    A mathematical model formulated as Δf/HmO-,(g) = a+∑5i=1bipi (i≠2) was constructed for the relationship between standard formation enthalpy ΔfHmO (g) and path index P, of substituted benzenes derivatives. An empiric equation for the calculation of ΔfHmO, (g) was worked out. The calculated values of standard formation enthalpy based on this model are excellently consistent with those from experimental for 55 organic compounds. The model is shown to be simple and of practical usefulness, particularly when required experimental data are unavailable.

  18. Characteristics of the benzene fraction of products resulting from the thermal destruction of bituminous petroleum

    Energy Technology Data Exchange (ETDEWEB)

    Kleev, A.M.; Margulis, B.Ya.; Martynov, A.A.; Vigdergauz, M.S.


    A description is given of a method for the chromatographic analysis of the 35 to 95/sup 0/C benzene feaction produced from the thermal destruction of bituminous petroleum. Aromatic, olefin, and paraffin-naphthene fractions were identified in the first stage of fluid chromatography with a fluorescent indicator. Gas chromatography was employed to undertake a detailed analysis of each fraction. The results of the analysis indicate that the use of a thermogas generator in the process of thermodestruction approximates the process of oxidative cracking. 11 references, 4 figures.

  19. The Photophysical Properties and Morphology of Fluorene- alt-benzene Based Conjugated Polymers

    Institute of Scientific and Technical Information of China (English)

    Guizhong Yang; Tianxi Liu; Min Wang; Peiyi Wu; Wei Huang


    @@ 1Introduction There has been wide interest in the photophysical properties of rod-like fluorene based conjugated polymers because of their potential applications in various optoelectronic devices, especially in polymers light-emitting diodes (PLEDs)[1]. In this work, a series of fluorene-alt-benzene based conjugated main chain polymers with different length alkyl side chains on phenylene ring were designed and successfully synthesized. The effect of alkyl chain length on the photophysical property, phase transition behavior and morphology structure of the polymers were investigated.

  20. A Topological Approach to the Correlation of Standard Formation Enthalpy with Path Index of Benzenes Derivatives

    Institute of Scientific and Technical Information of China (English)

    Li Liang-chao; Ni Cai-hua; Lin Qiu-yue


    A mathematical model formulated as △fHφm(g)= a + 5∑i=1 bipi (i ≠ 2) was constructed for the relationship between standard formation enthalpy △fH m (g) and path in-dex Pi of substituted benzenes derivatives. An empiric equation for the calculation of △f H0m(g) was worked out. The cal-culated values of standard formation enthalpy based on this model are excellently consistent with those from experimental for 55 organic compounds. The model is shown to be simple and of practical usefulness, particularly when required experimental data are unavailable.

  1. Specific determination of benzene in urine using dynamic headspace and mass-selective detection. (United States)

    Ljungkvist, G; Lärstad, M; Mathiasson, L


    A method for the determination of benzene in urine was developed, based on dynamic headspace and preconcentration of the analyte on a solid sorbent. The subsequent analysis by thermal desorption of the sorbent, capillary gas chromatography and mass-selective detection ascertained a low limit of detection (6.5 ng/l) and a highly specific determination. The limit of detection is an order of magnitude lower than that reported earlier and allows reliable quantitation of occupational exposure and of most environmental exposures. Samples could be stored frozen for at least a month without significant loss.

  2. Development of QSAR Model of substituted Benzene Sulphonamide using Multiple Regression Analysis

    Directory of Open Access Journals (Sweden)



    Full Text Available In continuation of our earlier work in this paper we studied 50 substituted Benzenesulphonamide using substituent nanofluorobutyl sulphonyl chloride (C4F9SO2Cl and pentafluoro benzene sulphonyl chloride (C6F5SO2Cl Accordingly we have development QSAR model of studied compounds. These models were derived using the parameters Balaban Index, Balaban-type index,(Jhetz, Jhetm, Jhetv, Jhete, Jhetp Balaban related index (F,G. and Randic connectivity index (χ1. The best suitable model is predicted on the basis of Maximum-R2 (R-squared.

  3. Hexa-μ-chlorido-hexachlorido(η6-hexamethylbenzenetrialuminium(IIIlanthanum(III benzene solvate

    Directory of Open Access Journals (Sweden)


    Full Text Available In the title compound, [Al3LaCl12(C12H18]·C6H6, all molecules are located on a mirror plane. Three chloridoaluminate groups and a hexamethylbenzene molecule are bound to the central lanthanum(III ion, forming a distorted pentagonal bipyramid with the η6-coordinated arene located at the apical position. The hexamethylbenzene ligand disordered between two orientations in a 1:1 ratio is also involved in parallel-slipped π–π stacking intermolecular interactions with a benzene solvent molecule [centroid–centroid distance 3.612 (4 Å].

  4. The effect of different electrodes on the electronic transmission of benzene junctions: Analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Mohebbi, Razie; Seyed-Yazdi, Jamileh, E-mail:


    In this paper we have investigated the electronic transmission of systems electrode–benzene–electrode using the Landauer approach. The effect of different electrodes made of metal (Au) and semiconductors (Si, TiO{sub 2}) is investigated. These three electrodes are compared between them and the results show that the electronic transmission of benzene junctions, when using semiconductor electrodes, is associated to a gap in transmission which is due to the electrodes band gap. As a consequence, a threshold voltage is necessary to obtain conducting channels.

  5. Direct Synthesis of Phenol from Benzene on an Activated Carbon Catalyst Treated with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    Cui-hong Chen; Jia-quan Xu; Ming-ming Jin; Gui-ying Li; Chang-wei Hu


    Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy,scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize toe samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.

  6. Direct amination of benzene to aniline with several typical vanadium complexes

    Institute of Scientific and Technical Information of China (English)

    Yu Fen Lv; Liang Fang Zhu; Qiu Yuan Liu; Bin Guo; Xiao Ke Hu; Chang Wei Hu


    The liquid-phase direct catalytic amination of benzene to aniline was performed in acetic acid water solvent using a series of vanadium(Ⅲ,Ⅳ,Ⅴ)complexes with N,O-or O,O-ligands as catalysts and hydroxylamine hydrochloride as the aminating agent.The vanadium complexes exhibited much higher selectivity towards the production of aniline than NaVO3 or VOSO4.Under the optimized conditions,an aniline yield of 42.5% and a TON of 48 with a high selectivity of above 99.9% was obtained using 0.2 mmol of[VO(OAc)2]as the catalyst.

  7. Organometallic benzene-vanadium wire: A one-dimensional half-metallic ferromagnet

    DEFF Research Database (Denmark)

    Maslyuk, V.; Bagrets, A.; Meded, V.


    methods. We predict that the ground state of the wire is a 100% spin-polarized ferromagnet (half-metal). Its density of states is metallic at the Fermi energy for the minority electrons and shows a semiconductor gap for the majority electrons. We find that the half-metallic behavior is conserved up to 12......% longitudinal elongation of the wire. Ab initio electron transport calculations reveal that finite size vanadium-benzene clusters coupled to ferromagnetic Ni or Co electrodes will work as nearly perfect spin filters....

  8. DFT study of electronic transfer properties of carboxyl and nitro substituted benzene

    Energy Technology Data Exchange (ETDEWEB)

    Megala, M.; Rajkumar, Beulah J. M., E-mail: [PG and Research Department of Physics, Lady Doak College, Madurai – 625002 (India)


    The electronic and optical transfer properties of Benzene, Benzoic Acid (BA), Nitrobenzene (NB) and Para Nitro Benzoic Acid (PNBA) at ground and first excited state has been investigated by the Density functional theory (DFT)and Time Dependent Density Functional Theory (TDDFT) using SVWN functional/3-21G basis set respectively. Possible intra-molecular charge transfer and n to π* transitions in the ground and the first excitation states have been predicted by the molecular orbitals and the Natural Bond Orbital (NBO) analysis. The simulated absorption spectra have been generated and the result compared with existing experimental results.

  9. Lipidic Carbo-benzenes: Molecular Probes of Magnetic Anisotropy and Stacking Properties of α-Graphyne. (United States)

    Zhu, Chongwei; Rives, Arnaud; Duhayon, Carine; Maraval, Valérie; Chauvin, Remi


    Solubilization of the C18 fundamental circuit of α-graphyne has been envisaged by decoration with aliphatic chains R = n-CnH2n+1. The synthesis and characterization of p-dialkyl-tetraphenyl-carbo-benzenes (n = 2, 8, 14, 20) are thus presented and compared to the monoalkyl series produced concomitantly. In both series, a dramatic enhancement of solubility in organic solvents (CH2Cl2, CHCl3) is observed for n ≥ 8, and in the dialkyl series, the melting-decomposition temperature of the solid products is shown to decrease linearly from 208 °C for n = 2 to 149 °C for n = 20. Fluoroalkyl analogues with R = n-C8H4F13 are also described. The products display classical UV-vis electronic spectra of carbo-benzenes in solution (λmax = 445.5 ± 1 nm, ε ≈ 200 000 L·mol(-1)·cm(-1)). They are also characterized by UV-vis absorption in the solid state, which is found to be correlated with the color and crystal packing. The methylene groups of R provide an experimental probe of the magnetic anisotropy and aromaticity of the C18 ring through the progressive NMR shielding of the (1)H nuclei from ca. 4.70 to 1.25 ppm going away from the border of the ring (as far as 8 Å away). All alkyl-carbo-benzenes were also found to be highly crystalline. Seven of them have been characterized by X-ray diffraction analysis and the C18 columnar packing compared in a systematic manner. Crystals of the diethyl and bistetradecyl derivatives, containing no solvent molecule, provided the first examples of direct π-stacking of carbo-benzene rings, with inter-ring distances very close to calculated interlayer distances in AB and ABC α-graphityne (3.255 and 3.206 Å vs 3.266 and 3.201 Å, respectively).

  10. Benzene on Cu(111): II. Molecular assembly due to Lateral van der Waals and Surface-State-Mediated Indirect Interactions (United States)

    Hyldgaard, Per; Berland, Kristian; Einstein, T. L.


    Experiments show that benzene condenses into two different structural phases: a compact and a sparse phase, both of approximately hexagonal symmetry. The vdW-DF calculations demonstrate that the denser benzene-overlayer phase, with lattice constant 6.74 ,s due to direct benzene-benzene vdW attraction. The structure of the second, sparser phase, with lattice spacing 10.24 ,s attributed to the indirect electronic interactions mediated by the well-known metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbatively the asymptotic form of this indirect interaction. Our extended vdW-DF scheme---which combines calculations of molecular physisorption, of direct intermolecular vdW coupling, and of indirect electronic interactions between the molecular adsorbates---accounts well for the structural phases of benzene on Cu(111). Our preliminary vdW-DF study of acene and quinone interactions provides building blocks for modeling of anthraquinone assembly on Cu(111).footnotetextG. Pawin, , L. Bartels, Science 313 (2006) 961

  11. Creation of carbon onions and coils at low temperature in near-critical benzene irradiated with an ultraviolet laser

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Takahiro [Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan); Watabe, Nami [Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan); Whitby, Raymond [School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockroft Building, Lewes Road, Brighton BN2 4GJ (United Kingdom); Maekawa, Toru [Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan)


    Gas-liquid coexistence curves terminate at their critical points, where second-order phase transitions occur. The specific heat and compressibility increase greatly as the fluid systems approach their critical points. As a result, thermal diffusion is suppressed and the perturbations of the temperature, pressure and density propagate as acoustic waves. In this paper, we irradiate near-critical benzene with a laser beam of 266 nm in wavelength, the energy flux of which is 1.3 and 3.9 mW mm{sup -2}, and show that benzene is dissociated and various carbon nano/microstructures such as carbon onions and coils are created. Carbon onions are produced in both subcritical (200 deg. C) and supercritical (290 deg. C) benzene, whereas carbon coils are produced on an alloy catalyst composed of (Fe:Cr:Ni = 74:18:8) in supercritical benzene irradiated with a laser beam of 3.9 mW mm{sup -2}. The operational temperature of the present method is much lower than that used in conventional carbon structure synthesizing methods and a large number of carbon structures, such as carbon onions and coils, are produced in supercritical benzene.

  12. Creation of carbon onions and coils at low temperature in near-critical benzene irradiated with an ultraviolet laser (United States)

    Fukuda, Takahiro; Watabe, Nami; Whitby, Raymond; Maekawa, Toru


    Gas-liquid coexistence curves terminate at their critical points, where second-order phase transitions occur. The specific heat and compressibility increase greatly as the fluid systems approach their critical points. As a result, thermal diffusion is suppressed and the perturbations of the temperature, pressure and density propagate as acoustic waves. In this paper, we irradiate near-critical benzene with a laser beam of 266 nm in wavelength, the energy flux of which is 1.3 and 3.9 mW mm-2, and show that benzene is dissociated and various carbon nano/microstructures such as carbon onions and coils are created. Carbon onions are produced in both subcritical (200 °C) and supercritical (290 °C) benzene, whereas carbon coils are produced on an alloy catalyst composed of (Fe:Cr:Ni = 74:18:8) in supercritical benzene irradiated with a laser beam of 3.9 mW mm-2. The operational temperature of the present method is much lower than that used in conventional carbon structure synthesizing methods and a large number of carbon structures, such as carbon onions and coils, are produced in supercritical benzene.

  13. A new certified reference material for benzene measurement in air on a sorbent tube: development and proficiency testing. (United States)

    Caurant, A; Lalère, B; Schbath, M-C; Stumpf, C; Sutour, C; Mace, T; Quisefit, J-P; Doussin, J-F; Vaslin-Reimann, S


    A certified matrix reference material (CRM) for the measurement of benzene in ambient air has been developed at Laboratoire National de Métrologie et d'Essais. The production of these CRMs was conducted using a gravimetric method fully traceable to the International System of Units. The CRMs were prepared by sampling an accurate mass of a gaseous primary reference material of benzene, using a high-precision laminar flowmeter and a mass flow controller, with a PerkinElmer sampler filled with Carbopack™ X sorbent. The relative standard deviations obtained for the preparation of a batch of 20 tubes loaded with 500 ng of benzene were below 0.2%. Each CRM is considered independent from the others and with its own certified value and an expanded uncertainty estimated to be within 0.5%, lower than the uncertainties of benzene CRMs already available worldwide. The stability of these materials was also established up to 12 months. These CRMs were implemented during proficiency testing, to evaluate the analytical performances of seven French laboratories involved in benzene air monitoring.

  14. Benzene Variability in a Region of Oil and Gas Extraction in the DJ Basin During DISCOVER-AQ/FRAPPE 2014 (United States)

    Halliday, H.; Wisthaler, A.; Thompson, A. M.; Mikoviny, T.; Müller, M.


    The 2014 DISCOVER-AQ/FRAPPE experiment was an opportunity for aircraft and ground-based sampling of trace gases in the Denver-Julesburg Basin. We measured volatile organic compounds (VOCs) with a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) in July and August of 2014 at NOAA's Platteville Atmospheric Observatory (40.1815 / -104.7268), a site in close proximity to multiple facilities for extraction, storage, transportation, processing and distribution of oil and gas. On selected days, continuous ground-based measurements were complemented by airborne PTR-MS measurements from NASA P-3B aircraft vertical profiles over Platteville. The spirals were further supported by pressurized canister samples analyzed by a GC-MS for a suite of VOCs. The data were used to characterize the variability of benzene at the collection site. Exceptionally high measurements of benzene from the southwest constrain a gas field benzene source that has been observed in previous studies. The chemistry at the site is heavily influenced by oil and gas activity, with local sources of benzene creating mixing ratios comparable to benzene measured over the Denver urban area.

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

    Directory of Open Access Journals (Sweden)

    Paolo Viotti


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

  16. High-performance Liquid Chromatographic Determination of Urinary Trans, Trans-Muconic Acid Excreted by Workers Occupationally Exposed to Benzene

    Institute of Scientific and Technical Information of China (English)



    To investigate the relationship between trans, trans-muconic acid (ttMA) as benzene metabolite of occupational workers and benzene concentration in air. Methods A rapid and sensitive high-performance liquid chromatography was developed to determine the level of urinary ttMA. ttMA was extrated from urinary samples in liquid-liquid phase a ODS (2) (5u) column (Φ4.6 mm× 150 mm) and detected at wavelength 264 nm in a UV detector using vanillic acid as an internal standard. The mobile phase was acetaticacid/tetrahydrofuran/methanol/water (v/v, 1:2:10:87). The method was validated with 56 urine samples collected from occupationally benzene-exposed individuals. Results A correlation coefficient (r = 0.9963 ) was found for ttMA ranging 0.10-10.00 μg/mL. The limit of detection was 0.10 μg/mL. The recovery and reproducibility were generally over 90%. There was a positive correlation between ttMA and benzene level in air. The equation was Y=0.859+0.108C (before work, r=-0.6200) or Y=1.980+0.179C (after work, r=0.7930). Conclusion This method can be used to determine and control the level of urinary ttMA in those who are occupationally exposed to benzene.

  17. Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China (United States)

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


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

  18. [Methodological aspects in environmental and biological monitoring of exposure to low doses of benzene: problems and possible solutions]. (United States)

    Tranfo, Giovanna; Paci, Enrico; Fustinoni, Silvia; Barbieri, Anna; Carrieri, Mariella


    This paper aims to examine some methods to measure human exposure to benzene, both in life and occupational environments, through environmental and biological monitoring, examining the critical issues and optimal conditions of use. The overall performance of environmental monitoring, from the analytical point of view, strongly depend on the choice of an appropriate method of sampling and analysis. Urinary SPMA and t, t-MA are the biomarkers listed by ACGIH to evaluate occupational exposure: most of the recent studies use HPLC with tandem mass spectrometry, but since t, t-MA is present in the urine in larger quantities it is also determinable with UV detectors. The urinary benzene is an index not officially included in the list of the ACGIH BEIs, but it is useful to assess exposure and benzene at low concentrations, that most frequently are found today in the occupational and life environments.

  19. JV Task 86 - Identifying the Source of Benzene in Indoor Air Using Different Compound Classes from TO-15 Data

    Energy Technology Data Exchange (ETDEWEB)

    Steven B. Hawthorne


    Volatile organic compound (VOC) data that had already been collected using EPA method TO-15 at four different sites under regulatory scrutiny (a school, strip mall, apartment complex, and business/residential neighborhood) were evaluated to determine whether the source of indoor air benzene was outdoor air or vapor intrusion from contaminated soil. Both the use of tracer organics characteristic of different sources and principal component statistical analysis demonstrated that the source of indoor air at virtually all indoor sampling locations was a result of outdoor air, and not contaminated soil in and near the indoor air-sampling locations. These results show that proposed remediation activities to remove benzene-contaminated soil are highly unlikely to reduce indoor air benzene concentrations. A manuscript describing these results is presently being prepared for submission to a peer-reviewed journal.

  20. Chronic myelogenous leukemia and benzene exposure: a systematic review and meta-analysis of the case-control literature. (United States)

    Lamm, Steven H; Engel, Arnold; Joshi, Kiran P; Byrd, Daniel M; Chen, Rusan


    Benzene exposure is well demonstrated as a cause of acute myelogenous leukemia, but not of chronic myelogenous leukemia. Previous literature reviews based on case series and cohort studies have not shown an association. We have now conducted a literature search for case-control studies that examine the association between benzene exposure and chronic myelogenous leukemia. Six case-control studies have been found. These derive from occupational groups, cancer registries, and a clinical laboratory. Their exposure ascertainments are all based on job histories, job-exposure matricies, or industrial hygiene data. The odds ratios (ORs) for individual studies range from 0.73 to 1.2. The pooled OR is 1.003 with 95% confidence interval (CI) of 0.94-1.07 (p=0.98) for both a fixed effects model and a random effects model. The case-control literature indicates that chronic myelogenous leukemia does not appear to be related to benzene exposure.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  2. Isonicotinic acid-ligated cobalt (II phthalocyanine-modified titania as photocatalyst for benzene degradation via fluorescent lamp

    Directory of Open Access Journals (Sweden)

    Joey Andrew A. Valinton


    Full Text Available The utilization of bis(isonicotinic acidphthalocyaninatocobalt (II [CoPc(isa2] incorporated on TiO2 has been studied as a photocatalyst to degrade benzene vapor under fluorescent lamp (indoor light conditions. The photocatalytic activity of [CoPc(isa2]-TiO2 compared to TiO2 showed an increase in the extent of degradation. The axial isonicotinic acid ligand attached to CoPc improved the degradation rate of benzene as compared with unligated CoPc-TiO2 which may be attributed to the enhancement of electronic structure in the complex due to the additional isonicotinic acid ligand and its possible attachment to the TiO2 surface through the carboxylic acid moiety. Therefore, covalently-linked CoPc(isa2 to TiO2 can enhance the extent of photodegradation of benzene and other common volatile organic compounds under indoor lighting conditions.

  3. Effect of subacute benzene exposure on the activity of two neuropeptide-degrading enzymes in the rat brain. (United States)

    de Gandarias, J M; Casis, O; Irazusta, J; Echevarría, E; Casis, L


    Benzene (Bz) is an important industrial chemical, a petroleum by-product, a component of unleaded gas, and thus a ubiquitous environmental pollutant. It is well established that this organic solvent possesses neurotoxic and behavioral effects. However, the neurochemical mechanism of the solvent action remains obscure. The aminopeptidases (AP) are proteolytic enzymes that have been proposed as a candidate regulator of the degradation of several neuropeptides. In this work, changes in Lys- and Leu-aminopeptidase activities in several rat brain regions after benzene administration are described. The AP activity was determined by measuring the rate of hydrolysis of the artificial substrates Lys- and Leu-2-naphthylamides (fluorimetrically detected in triplicate). Both enzyme activities decrease in the thalamus, hypothalamus, hippocampus, and amygdala after Bz treatment. It is suggested that these aminopeptidase activities play a part in the benzene action mechanism, possibly by regulating the activity of several neuroactive peptides.

  4. Catalytic degradation of gaseous benzene by using TiO2/goethite immobilized on palygorskite: Preparation, characterization and mechanism (United States)

    Ma, Jianzhong; Zhu, Chengzhu; Lu, Jun; Liu, Haibo; Huang, Li; Chen, Tianhu; Chen, Dong


    The nano-TiO2/goethite/palygorskite catalysts were prepared by sol-gel method. The morphology and structure of the catalysts were analyzed by X-ray diffraction (XRD), UV-Vis reflection spectrometer, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and N2 adsorption-desorption measurement. The results indicated that the self-made catalysts had excellent catalytic performance on gaseous benzene degradation. In the case of benzene concentration at 30 mg/m3, the degradation efficiency, over TiO2/goethite/palygorskite composite with mass ratio of 10:5:5, reached 70.4% after 180 min 254 nm UV irradiation. The reaction mechanism and kinetics study showed that palygorskite/goethite/TiO2 composites photocatalytic degradation benzene was mainly caused by oxidizing property of electron-holes and oxygen synergy effect.

  5. Synthesis, characterization, and antifungal activity of novel inulin derivatives with chlorinated benzene. (United States)

    Guo, Zhanyong; Li, Qing; Wang, Gang; Dong, Fang; Zhou, Haoyuan; Zhang, Jing


    A group of novel inulin derivatives containing benzene or chlorinated benzene were synthesized by reaction of chloracetyl inulin (CAIL) with the Schiff bases of 4-amino-pyridine, including (2-pyridyl)acetyl inulin chloride (PAIL), 2-[4-(2-chlorobenzylideneamino)-pyridyl]acetyl inulin chloride (2CPAIL), 2-[4-(4-chlorobenzylideneamino)-pyridyl]acetyl inulin chloride (4CPAIL), and 2-[4-(2,4-dichlorobenzylideneamino)-pyridyl]acetyl inulin chloride (2,4DCPAIL). Their antifungal activity against three kinds of phytopathogens was estimated by hypha measurement in vitro. Of all the synthesized chitosan derivatives, 2,4DCPAIL inhibited the growth of the tested phytopathogens with inhibitory indices of 67%, 47%, and 43% against Colletotrichum lagenarium (Pass) halst, Phomopsis asparagi (Sacc.) Bubak and Fusarium oxysporum (schl.) F.sp. niveum (F. oxysporum) respectively at 1.0 mg/mL. The results indicate that all the inulin derivatives have better antifungal activity than inulin, and the inhibitory index is affected by the chlorine atom grafted to the inulin derivatives.

  6. Rings sliding on a honeycomb network: Adsorption contours, interactions, and assembly of benzene on Cu(111) (United States)

    Berland, K.; Einstein, T. L.; Hyldgaard, P.


    Using a van der Waals density functional (vdW-DF) [Phys. Rev. Lett. 92, 246401 (2004)], we perform ab initio calculations for the adsorption energy of benzene (Bz) on Cu(111) as a function of lateral position and height. We find that the vdW-DF inclusion of nonlocal correlations (responsible for dispersive interactions) changes the relative stability of eight binding-position options and increases the binding energy by over an order of magnitude, achieving good agreement with experiment. The admolecules can move almost freely along a honeycomb web of “corridors” passing between fcc and hcp hollow sites via bridge sites. Our diffusion barriers (for dilute and two condensed adsorbate phases) are consistent with experimental observations. Further vdW-DF calculations suggest that the more compact (hexagonal) Bz-overlayer phase, with lattice constant a=6.74Å , is due to direct Bz-Bz vdW attraction, which extends to ˜8Å . We attribute the second, sparser hexagonal Bz phase, with a=10.24Å , to indirect electronic interactions mediated by the metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbationally the asymptotic form of this indirect interaction. Thus, we can account well for benzene self-organization on Cu(111).

  7. Photocatalytic oxidation of gaseous benzene over nanosized TiO2 prepared by solvothermal method

    Institute of Scientific and Technical Information of China (English)


    Nanosized TiO2 particles were prepared by solvothermal method using tetrabutyl titanate as precursor, ethanol and water as solvents, and a facile immobilization method of nanosized TiO2 particles on woven glass fabric was developed. The samples obtained under various preparation conditions were characterized by means of thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), and Brunauer-Emmett-Teller (BET). The results show that the cube-shape of TiO2 prepared by solvothermal method has good crystallinity of (101) surface, higher thermal stability and large specific surface area. Scanning electron microscopy (SEM) images confirmed that the immobilized TiO2 film was uniformly distributed and clung to the substrate firmly. The photocatalytic activity of the catalysts was tested using photocatalytic oxidation of gaseous benzene. The results show that the TiO2 calcined after solvothermal treatment suffers from lower specific surface area, and hence decreases its photocatalytic activity. The photocatalytic activities of the TiO2 by solvothermal treatment with or without calcination in degradation 400 mg/m3 benzene are 3.7 and 4.1 times as high as catalyst without solvothermal treatment, respectively.

  8. Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays. (United States)

    Wahyudi, Agung; Bartzke, Mariana; Küster, Eberhard; Bogaert, Patrick


    Ecotoxicological bioassays, e.g. based on Danio rerio teratogenicity (DarT) or the acute luminescence inhibition with Vibrio fischeri, could potentially lead to significant benefits for detecting on site contaminations on qualitative or semi-quantitative bases. The aim was to use the observed effects of two ecotoxicological assays for estimating the extent of a Benzene groundwater contamination plume. We used a Maximum Entropy (MaxEnt) method to rebuild a bivariate probability table that links the observed toxicity from the bioassays with Benzene concentrations. Compared with direct mapping of the contamination plume as obtained from groundwater samples, the MaxEnt concentration map exhibits on average slightly higher concentrations though the global pattern is close to it. This suggest MaxEnt is a valuable method to build a relationship between quantitative data, e.g. contaminant concentrations, and more qualitative or indirect measurements, in a spatial mapping framework, which is especially useful when clear quantitative relation is not at hand.

  9. A Au-functionalized ZnO nanowire gas sensor for detection of benzene and toluene. (United States)

    Wang, Liwei; Wang, Shurong; Xu, Mijuan; Hu, Xiaojing; Zhang, Hongxin; Wang, Yanshuang; Huang, Weiping


    A novel sensing hybrid-material of Au nanoparticles (Au NPs)-functionalized ZnO nanowires (Au-ZnO NWs) was successfully synthesized by a two-stage solution process. First, ZnO NWs were fabricated via a low-temperature one-pot hydrothermal method with SDSN introduced as a structure-directing agent. Afterward, the as-prepared ZnO NWs were used as supports to load Au NPs with small sizes via precipitating HAuCl4 aqueous solution with ammonia. The obtained samples were characterized by means of XRD, SEM, TEM and EDX. Both pristine and Au-ZnO NWs were practically applied as gas sensors to compare the effect of Au NPs on the sensing performances and the obtained results demonstrated that after functionalization by catalytic Au NPs, the hybrid sensor exhibited not only faster response and recovery speeds but also a higher response to benzene and toluene than the pristine ZnO sensor at 340 °C, especially showing high selectivity and long-term stability for low concentration toluene, which is rarely reported with this method, indicating its original sensor application in detecting benzene and toluene. To interpret the enhanced gas sensing mechanism, the strong spillover effect of the Au NPs and the increased Schottky barriers caused by the electronic interaction between Au NPs and ZnO NW support are believed to contribute to the improved sensor performance.

  10. Enhanced catalytic properties of mesoporous mordenite for benzylation of benzene with benzyl alcohol (United States)

    Saxena, Sandeep K.; Viswanadham, Nagabhatla


    Zeolite mordenite has been treated with nitric acid at different severities so as to facilitate the framework dealumination and optimization of the textural properties such as acidity and porosity. The samples obtained have been characterized by X-ray diffraction, FTIR, SEM, TEM, surface area, porosity by N2 adsorption and ammonia TPD. The resultant samples have been evaluated towards the bulky alkylation reaction of benzylation of benzene with benzyl alcohol. The studies indicated the improvement in the textural properties such as surface area, pore volume and acidity of the samples after the acid treatment. While, the phenomenon of enhancement in properties was exhibited by all the acid treated mordenite samples, the highest improvement in properties was observed at a particular condition of acid treatment (SM-2 sample). This particular sample also exhibited highest acidity and the presence of ∼10 nm size pores that resulted in the effective catalytic activity towards the bulky alkylation reaction of benzene with benzyl alcohol to produce high yields of di-phenyl methane.

  11. Effect of water contaminated with phthalate, benzene and cyclohexane on Clarias gariepinus' cellular system. (United States)

    Adeyemi, O; Oginni, O; Osubor, C C; Adeyemi, O; Oloyede, O B; Oladiji, A T; Adebayo, E A


    This study evaluates the effect of water contaminated with phthalate, benzene and cyclohexane (major components of municipal waste in Nigeria) on the cellular system of Clarias gariepinus. Standard enzyme assays were conducted for alkaline phosphatase, acid phosphatase, alanine transaminase, aspartate transaminase, lactate dehydrogenase, gamma glutamyl transpeptidase of selected tissues of C. gariepinus cultivated in contaminated water over a period of 56 days. Generally, a significant decrease in the activity of the enzymes of the tissues of C. gariepinus cultivated in contaminated water was observed relative to the control (pgariepinus cultivated in phthalate contaminated water was found to be 8.26+/-1.42 while that of control was 14.42+/-1.09. The activity of serum gamma glutamyl transpeptidase of serum of the same group of fish was found to be twice that of control. It could be inferred that membrane integrity of the tissues studied are compromised and that tissue dysfunction may result. Consumption of C. gariepinus cultivated in water contaminated with phthalate, benzene and cyclohexane could pose threats to public health.

  12. Continuous reaction performances of benzene alkylation with long chain olefins catalyzed by ionic liquid

    Institute of Scientific and Technical Information of China (English)

    Congzhen QIAO; Chengyue LI


    Based on a compulsive mixing-reacting-sepa-rating-recycling small experimental setup,the continuous reaction performances of benzene alkylation with long chain olefins catalyzed by [BMIM]Cl-AlCl3 ionic liquid were investigated. Three different situations including normal continuous operation mode (reagent materials), sidetrack feeding from different axial positions along the static mixing reactor (reagent materials) and normal con-tinuous alkylation using industrial paraffin and olefins materials were examined. Even under the relatively hype-critical reaction conditions, the single pass conversion of pure 1-dodecene could reach to nearly 100.0%, and the selectivity of 2-phenyl isomer was higher than 37.7%. Although the positions along the reactor for sidetrack feeding were different, the 100.0% single pass conversion of 1-dodecene was also attained before the outlet of the reactor. The refined industrial olefins as raw material could meet with the requirements of continuous alkyla-tion. The influences of impurities such as di-olefins and non-benzene aromatics on the catalytic activity and stability should be studied further.

  13. Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research. (United States)

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


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

  14. Photodegradation of benzene by TiO2 nanoparticles prepared by flame CVD process

    Institute of Scientific and Technical Information of China (English)

    Hongyong Xie; Luping Zhu; Lingling Wang; Shengwen Chen; Dandan Yang; Lijun Yang; Guilan Gao; Hao Yuan


    Photodegradation of benzene at ppb levels by mixed-phase TiO2 nanoparticles,synthesized by the oxidation of TiCl4 in propane/air turbulent flame chemical vapor deposition (CVD) process,is investigated experimentally by using a tubular photoreactor with thin TiO2 films coated on the reactor wall by sedimentation. Effects of inlet benzene concentration from 10 to 300 μg/m3,futile mass fraction from about 20 to 50% and photoluminescence (PL) intensity of TiO2 nanoparticles on degradation degree are examined under the conditions of 70% relative humidity,38 μg/cm2 catalyst loading,24 mW/cm2 UV irradiation of 254 nm and 5.7 s residence time in the reactor. Based on experimental results,separation of photoinduced electron (e-) and hole (h+) pairs by rutile phase is discussed as photo-induced electron (e-) in anatase phase will migrate to rutile surface due to that the potential of conductive band of rutile is lower than that of anatase,leading to more holes ready on anatase surface for oxidation reactions.


    Directory of Open Access Journals (Sweden)

    S. J. Shahtaheri, H. R. Heidari, F. Golbabaei, M. Alimohammadi, A. Rahimi Froshani


    Full Text Available Conventional analytical method for organic pollutants in water requires extraction of the pollutants, using hazardous solvent. Solid phase microextraction is a solvent free equilibrium extraction method, in which, proper calibration can allow quantitative determinations of organic pollutants at a very good sensitivity without the use of any organic solvent. Because individual volatile organic carbons are generally exposed environmentally and present in urine only at trace levels, a sensitive and accurate determination technique is essential. So, this study describes the optimization of headspace solid phase microextraction (HS-SPME followed by GC-FID for benzene in spiked urine. Through this investigations, the parameters affecting the extraction and gas chromatographic determination of analytes, including extraction time, temperature, desorption temperature, desorption time, salt addition, sample pH, sample volume and sample agitation were studied. An optimized headspace extraction was carried out at 30°C for 6 min in the presence of 0.2 g/mL of NaCl in the sample solution. Desorption of the analytes was carried out for 60 sec. at 250°C. The optimized procedure was 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. The accuracy, linearity, detection limits were also determined. The headspace solid phase microextraction, GC-FID technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine benzene in spiked urine.

  16. Alkylation Activity of Benzene with Syngas over Cu-based Catalysts

    Institute of Scientific and Technical Information of China (English)

    Zhao Xuebin; Zeng Feng; Zhao Bin; Gu Haohui


    A series of Cu-based catalysts were developed for alkylation of benzene with syngas. The catalyst samples were prepared by the impregnation method, and were characterized by XRD, XRF, NH3-TPD, and TEM and evaluated in a ifxed bed reactor. The optimized reaction temperature of Cu/Al2O3/ZSM-5 catalyst was 350℃, while higher contents of cop-per were conducive to alkylation of benzene with syngas. The new medium strength acid centers in the catalyst created by Cu were beneifcial to alkylation. Hydrogenation reaction of CO was executed on the metal centers without dissociation, Dimethyl ether (DME) was the major intermediate over Cu-based catalysts. Higher selectivity of methylation and lower selectivity of heavy aromatics were conifrmed after the secondmetal(Zn, Mn, or V) was added to the copper catalyst. Cu was partly covered by Zn in the Cu-Zn/Al2O3/ZSM-5 catalyst leading to low dispersion and low activity of copper. Cu-Mn/Al2O3/ZSM-5 catalyst possessed the best yield of methylation product. Cu-Mn composite oxides were probably formed in fresh catalyst, which blocked the sintering of Cu in the reaction process. The loading of Cu decreased dramatically after the introduction of V, while causing an increase of the amount of medium strength acid centers at the same time. V prevented the sintering of copper particles during the reducing process and had a promoting effect on the activity of Cu.

  17. Benzene destruction in claus process by sulfur dioxide: A reaction kinetics study

    KAUST Repository

    Sinha, Sourab


    Benzene, toluene and xylene (BTX) are present as contaminants in the H 2S gas stream entering a Claus furnace. The exhaust gases from the furnace enter catalytic units, where BTX form soot particles. These particles clog and deactivate the catalysts. A solution to this problem is BTX oxidation before the gases enter catalyst beds. This work presents a theoretical investigation on benzene oxidation by SO2. Density functional theory is used to develop a detailed mechanism for phenyl radical -SO2 interactions. The mechanism begins with SO2 addition to phenyl radical after overcoming an energy barrier of 6.4 kJ/mol. This addition reaction is highly exothermic, where a reaction energy of 182 kJ/mol is released. The most favorable pathway involves O-S bond breakage, leading to the release of SO. A remarkable similarity between the pathways for phenyl radical oxidation by O2 and its oxidation by SO2 is observed. The reaction rate constants are also evaluated to facilitate process simulations. © 2014 American Chemical Society.

  18. π Type Lithium Bond Interaction between Ethylene,Acetylene,or Benzene and Amido-lithium

    Institute of Scientific and Technical Information of China (English)

    YUAN,Kun; LIU,Yanzhi; L(U),Lingling; ZHU,Yuancheng; ZHANG,Ji; ZHANG,dunyan


    The optimization geometries and interaction energy corrected by basis set super-position error (BSSE) of the lithium bond complexes between ethylene,acetylene,or benzene and amido-lithium have been calculated at the B3L YP/6-311++G** and MP2/6-311 ++-G** levels.And only one configuration was obtained for each lithium bond system.All the equilibrium geometries were confirmed to be stable state by analytical frequency computations.The calculations showed that all the N(2)-Li(4) bond lengths increased obviously and the red shift of N(2)-Li(4) stretching frequency occurred after complexes formed.The calculated binding energies with BSSE and zero-point vibrational energy corrections of complexes Ⅰ,Ⅱ and Ⅲ are -26.04,-24.86 and -30.02 kJ·mol-1 via an MP2 method,respectively.Natural bond orbital (NBO) theory analysis revealed that the three complexes were all formed with π type lithium bond interaction between ethylene,acetylene,or benzene and amido-lithium.

  19. 1,4-Dialkynylbutatrienes: synthesis, stability, and perspectives in the chemistry of carbo-benzenes. (United States)

    Maraval, Valérie; Leroyer, Léo; Harano, Aya; Barthes, Cécile; Saquet, Alix; Duhayon, Carine; Shinmyozu, Teruo; Chauvin, Remi


    The π-electron-rich C(8)-conjugated sequence of 1,4-dialkynylbutatrienes is identified as a fragile and fascinating motif occurring in carbo-benzene derivatives, and in Diederich's 1,4-bis(arylethynyl)- or 1,4-bis(triisopropylsilylethynyl)butatriene "capped" representatives, in particular, in tetraalkynylbutatriene. The family of symmetrical 1,4-dialkynylbutatrienes (E-C≡C)RC=C=C=CR(C≡C-E) is extended to functional caps (E=H, CH(3), C≡CPh, CPh=CHBr, or CPh=CBr(2)) with non-alkynyl substituents at the sp(2) vertices (R=Ph or CF(3)). The targets were selected for their potential in appealing retrosynthetic routes to carbo-benzenes, in which the aromatic C(18) macrocycle would be directly generated by sequential metathesis or reductive coupling processes. The functional 1,4-dialkynylbutrienes were synthesized by either classical methods used for the preparation of generic butatrienes (R'Li/CuX-mediated reductive coupling of gem-dihaloenynes or SnCl(2)/HCl-mediated reduction of 3,6-dioxy-octa-1,4,7-triyne precursors). Their spectroscopic and electrochemical properties are compared and analyzed on the basis of the relative extent of total conjugation.

  20. Gas phase UV spectrum of a Cu(II)-bis(benzene) sandwich complex: experiment and theory. (United States)

    Ma, Lifu; Koka, Joseph; Stace, Anthony J; Cox, Hazel


    Photofragmentation with tunable UV radiation has been used to generate a spectrum for the copper-bis(benzene) complex, [Cu(C6H6)2](2+), in the gas phase. The ions were held in an ion trap where their temperature was reduced to ∼150 K, whereby the spectrum revealed two broad features at ∼38,200 and ∼45,700 cm(-1). Detailed calculations using density functional theory (DFT) show the complex can occupy three minimum energy structures with C2v and C2 (staggered and eclipsed) symmetries. Adiabatic time-dependent DFT (TDDFT) has been used to identify electronic transitions in [Cu(benzene)2](2+), and the calculations show these to fall into two groups that are in excellent agreement with the experimental data. However, the open-shell electronic configuration of Cu(2+) (d(9)) may give rise to excited states with double-excitation character, and the single-excitation adiabatic TDDFT treatment leads to extensive spin contamination. By quantifying the extent of spin contamination and allowing for the inclusion of a small percentage (∼10%), the theory can provide quantitative agreement with the experimental data.

  1. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

    CERN Document Server

    Azadi, Sam


    We study the low-pressure (0 to 10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo (QMC) and density functional theory (DFT) methods. We consider the $Pbca$, $P4_32_12$, and $P2_1/c$ structures as the best candidates for phase I and phase II. We perform diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. We use density functional perturbation theory to compute phonon contribution in the free-energy calculations. Our DFT enthalpy-pressure phase diagram indicates that the $Pbca$ and $P2_1/c$ structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature $Pbca$ to $P2_1/c$ phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations show an estimate of 50.6$\\pm$0.5 kJ/mol for crystalline benzene lattice energy.

  2. Comparative Analysis between Conventional PI and Fuzzy LogicPI Controllers for Indoor Benzene Concentrations

    Directory of Open Access Journals (Sweden)

    Nun Pitalúa-Díaz


    Full Text Available Exposure to hazardous concentrations of volatile organic compounds indoors in small workshops could affect the health of workers, resulting in respirative diseases, severe intoxication or even cancer. Controlling the concentration of volatile organic compounds is required to prevent harmful conditions for workers in indoor environments. In this document, PI and fuzzy PI controllers were used to reduce hazardous indoor air benzene concentrations in small workplaces. The workshop is represented by means of a well-mixed room model. From the knowledge obtained from the model, PI and fuzzy PI controllers were designed and their performances were compared. Both controllers were able to maintain the benzene concentration within secure levels for the workers. The fuzzy PI controller performed more efficiently than the PI controller. Both approaches could be expanded to control multiple extractor fans in order to reduce the air pollution in a shorter time. The results from the comparative analysis showed that implementing a fuzzy logic PI controller is promising for assuring indoor air quality in this kind of hazardous work environment.

  3. 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.

  4. Metabolic Polymorphisms and Clinical Findings Related to Benzene Poisoning Detected in Exposed Brazilian Gas-Station Workers

    Directory of Open Access Journals (Sweden)

    Simone Mitri


    Full Text Available Benzene is a ubiquitous environmental pollutant and an important industrial chemical present in both gasoline and motor vehicle emissions. Occupational human exposure to benzene occurs in the petrochemical and petroleum refining industries as well as in gas-station workers, where it can lead to benzene poisoning (BP, but the mechanisms of BP are not completely understood. In Brazil, a significant number of gas-station service workers are employed. The aim of the present study was to evaluate alterations related to BP and metabolic polymorphisms in gas-station service workers exposed to benzene in the city of Rio de Janeiro, Brazil. Occupational exposure was based on clinical findings related to BP, and metabolic polymorphisms in 114 Brazilian gas-station attendants. These workers were divided into No Clinical Findings (NCF and Clinical Findings (CF groups. Neutrophil and Mean Corpuscular Volume (MCV showed a significant difference between the two study groups, and neutrophil has the greatest impact on the alterations suggestive of BP. The clinical findings revealed higher frequencies of symptoms in the CF group, although not all members presented statistical significance. The frequencies of alleles related to risk were higher in the CF group for GSTM1, GSTT1, CYP2E1 7632T > A, but lower for NQO1 and CYP2E1 1053C > T genotypes. Moreover, an association was found between GSTM1 null and alterations related to BP, but we did not observe any effects of other polymorphisms. Variations in benzene metabolizing genes may modify benzene toxicity and should be taken into consideration during risk assessment evaluations.

  5. CYP2E1 regulation by benzene and other small organic chemicals in rat liver and peripheral lymphocytes. (United States)

    González-Jasso, Eva; López, Tomás; Lucas, Daniele; Berthou, Francois; Manno, Maurizio; Ortega, Arturo; Albores, Arnulfo


    The inducibility of CYP2E1 was investigated in liver and peripheral lymphocytes of rats treated with benzene (0-10 mmol/kg body weight (bw), daily for 3 days, i.p., or 0 and 5 mmol/kg bw, daily for 14 days, i.p.) or toluene (0 and 5 mmol/kg bw, daily for 3 days, i.p.) and compared with that of pyridine (5 mmol/kg bw, i.p.) or acetone (5% in drinking water) both daily for 3 days. Acute benzene treatment (5 mmol/kg bw) increased both CYP2E1 apo-protein (2-fold) and p-nitrophenol hydroxylase (p-NPH) activity (1.4-fold) in liver, and CYP2E1 mRNA in both liver (2.2-fold) and peripheral lymphocytes (2.9-fold). The response to toluene was qualitatively similar, although smaller than that to benzene. As expected, acetone and pyridine treatments resulted in a 2- to 3-fold increase of p-NPH activity and CYP2E1 apo-protein content in liver, but not the mRNA levels. In addition, acute benzene and acetone treatments increased the 6-hydroxychlorzoxazone/chlorzoxazone metabolic ratio 1.6- and 3.1-fold, respectively. The subchronic treatment with benzene increased CYP2E1 mRNA and apo-protein from days 2 and 3 to day 14, respectively, whereas the enzyme activity increased transiently on days 3 and 5 only. These results show that acute/subacute benzene and acute toluene treatments induce CYP2E1 expression probably through a similar mechanism which might be different from that of pyridine or acetone, in that the former increase mRNA levels, both in liver and in peripheral lymphocytes, whereas the latter stabilized the apo-protein.

  6. Exposure to methyl tert-butyl ether, benzene, and total hydrocarbons at the Singapore-Malaysia causeway immigration checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.; Ong, H.Y.; Kok, P.W. [and others


    The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weighted average concentrations measured were 1.05 ppm for MTBE, 2.01 ppm for benzene, and 34 ppm for THC. It was found that motorbikes emitted a more significant amount of pollutants compared with motor cars. On average, officers at the motorcycle booths were exposed to four to five times higher levels of VOCs (GMs of 0.07 ppm, 0.23 ppm, and 4.7 ppm for MTBE, benzene, and THC) than their counterparts at the motor car booths (GMs of 0.01 ppm, 0.05 ppm, and 1.5 ppm). The airborne concentrations of all three pollutants correlated with the flow of vehicle traffic. Close correlations were also noted for the concentrations in ambient air for the three pollutants measured. Benzene and MTBE had a correlation coefficient of 0.97. The overall findings showed that the concentrations of various VOCs were closely related to the traffic density, suggesting that they were from a common source, such as exhaust emissions from the vehicles. The results also indicated that although benzene, MTBE, and THC are known to be volatile, a significant amount could still be detected in the ambient environment, thus contributing to our exposure to these compounds. 4 refs., 6 figs.

  7. Chapter 13 Theoretical and Experimental Studies of the Gas-Phase Cl-Atom Initiated Reactions of Benzene and Toluene (United States)

    Ryzhkov, A.; Ariya, P. A.; Raofie, F.; Niki, H.; Harris, G. W.

    The reactions of benzene (Bz) and toluene (PhMe) with chlorine atoms in the gas phase have been studied using both theoretical and experimental techniques. Energy and geometry of reaction complexes and transition states were calculated in the Cl-atom initiated reaction of benzene and toluene using modern hybrid functional PBE0 method with the aug-pc1 basis set with an additional CCSD(T)/aug-CC-pVDZ energy single point calculation. Three stationary structures have been found for the Bz...Cl complex: hexahapto-complex, [pi]-complex and [sigma]-complex. The first one is a transition state between two opposite [pi]-complexes. PhMe...Cl has additional structures due to ipso-, ortho-, meta- and para-isomerization. The stability of all calculated complexes was determined and compared. Two reaction pathways for benzene and toluene with a Cl atom were evaluated: (a) the hydrogen abstraction of benzene and toluene by Cl atom, which is seemingly barrierless and endothermic, and (b) the hydrogen substitution reaction that in contrast has a relatively high energy of activation. Rate coefficients for these same reactions were measured using ethane, n-butane, and chloro-, dichloro- and trichloromethane, as reference compounds, with gas chromatography equipped with mass detection spectrometry and flame ionization detection (GC-MSD and GC-FID). The reaction rates were estimated as (5.57±0.15)×10-11 and for benzene and toluene, respectively. Chlorinated products of the reactions were analyzed by GS-MS. Chlorobenzene was the only identified product between a reaction of benzene and the Cl atom. The major products of the PhMe + Cl reaction were chloromethylbenzene with ortho- and para-chlorotoluenes.

  8. Concentrations of benzene and toluene in the atmosphere of the southwestern area at the Mexico City Metropolitan Zone (United States)

    Bravo, Humberto; Sosa, Rodolfo; Sánchez, Pablo; Bueno, Emma; González, Laura

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

  9. CH-{\\pi} interaction-induced deep orbital deformation in a benzene-methane weak binding system

    CERN Document Server

    Li, Jianfu


    The nonbonding interaction between benzene and methane, called CH-{\\pi} interaction, plays an important role in physical, chemical, and biological fields. CH-{\\pi} interaction can decrease the system total energy and promote the formation of special geometric configurations. This work investigates systemically the orbital distribution and composition of the benzene-methane complex for the first time using ab initio calculation based on different methods and basis sets. Surprisingly, we find strong deformation in HOMO-4 and LUMO+2 induced by CH-{\\pi} interaction, extending the general view that nonbonding interaction does not cause orbital change of molecules.

  10. Crystal structure of 2-benzene­sulfon­amido-3-hy­droxy­propanoic acid (United States)

    Jabeen, Nabila; Mushtaq, Misbah; Danish, Muhammad; Tahir, Muhammad Nawaz; Raza, Muhammad Asam


    In the title compound, C9H11NO5S, the O=S=O plane of the sulfonyl group is twisted at a dihedral angle of 52.54 (16)° with respect to the benzene ring. The dihedral angle between the carb­oxy­lic acid group and the benzene ring is 49.91 (16)°. In the crystal, C—H⋯O, N—H⋯O and O—H⋯O hydrogen bonds link the mol­ecules into (001) sheets. PMID:26594589

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  12. Poly[di-μ4-benzene-1,4-dicarboxylato-μ6-succinato-diholmium(III

    Directory of Open Access Journals (Sweden)

    Qin He


    Full Text Available The title compound, [Ho2(C4H4O4(C8H4O42]n, was synthesized hydrothermally. The Ho atom is coordinated by four O atoms from four benzene-1,4-dicarboxylate (BDC anions and four O atoms from three succinate anions, in a distorted square-antiprismatic coordination geometry. The antiprisms are bridged by the benzene-1,4-dicarboxylate and succinate anions, into a three-dimensional coordination network. The succinate anions are located on centres of inversion.

  13. Comparative Study of the Intermolecular Dynamics of Benzene/Ionic Liquid Mixtures and Benzyl Functionalized Ionic Liquids: Femtosecond OKE Spectroscopic Measurements (United States)

    Quitevis, Edward; Xue, Lianjie; Tamas, George


    Ionic liquids (ILs) are salts with melting points below 100 °C that are comprised of an organic cation and an inorganic or organic anion. There is great interest in obtaining a molecular level understanding of their unique physical and chemical properties, of which one of them is their ability, despite being inherently polar liquids, to dissolve large quantities of nonpolar aromatic compounds. In order to understand further the solvation of aromatic molecules in ILs, we have performed optical effect (OKE) spectroscopic measurements on 1-benzyl-3-methylimidazolum bistriflate, 1,3-dibenzylimidazolum bistriflate and the corresponding 1:1 and 2:1 benzene/1,3-dimethylimazolium bistrifate (C6H6/C1C1) mixtures. In contrast to being free in benzene/IL mixtures, the benzene rings are tethered to the imidazolium ring via methylene linkages in the case of first two ILs. The intermolecular Kerr spectra indicate that the motion of the benzene rings becomes increasingly more restricted in going from neat benzene to benzene dissolved in 1,3-dimethylimazolium bistrifate to benzene rings tethered to the imidazolium ring. This restriction causes the Kerr spectra effectively to shift to higher frequency in going from neat liquid benzene to C6H6/C1C1 mixtures to benzylimidazolium ILs. This work was supported by NSF Grant CHE-1153077.

  14. Diffusion and Adsorption of Benzene and Propylene in MFI, MWW and BEA Zeolites: Molecular Dynamics and Grand Canonical Monte Carlo Simulations

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-yan; JIAO Wei; XIANG Shu-guang; LI Jian-wei


    The diffusion and adsorption behaviors of benzene and propylene in zeolites MFI, MWW and BEA have been studied by molecular dynamics(MD) and grand canonical Monte Carlo(GCMC) simulations. The diffusion coefficients of benzene and propylene in MFI, MWW and BEA zeolites were calculated by simulating the mean-square displacements(MSD) at 298 and 600 K. Benzene and propylene showed the different adsorption rules in the channels of the three zeolites. For propylene, the molecular loadings decreased in the order: BEA(linear channel)〉BEA (tortuous channel)〉MFI(linear channel)〉MWW(l2-membered rings, 12MR channel)〉MFI(tortuous channel)〉MWW (10-membered rings, 10MR channel); for benzene, the molecular loadings decreased in the order: BEA(linear channel)〉BEA(tortuous channel)〉MWW(l2MR channel)〉MFI(linear channel)〉MFl(tortuous channel)〉MWW(10MR channel). Besides, the adsorption isotherms of benzene and propylene in the three zeolites at 298 and 443 K were simulated. The results show that the different factors influenced the molecular adsorption at various temperatures and pressures, leading to the different rules for the adsorption of benzene and propylene molecules in the zeolites. At a low pressure, the unfavorable energy would make the loadings of propylene lower than those of benzene. When pressure was higher than 0.25 kPa, the adsorption of benzene in MFI would nearly reach saturation.

  15. 空气及非金属材料脱气中苯的GC/MS-SIM分析方法%GC/MS- SIM Analysis Method for Benzene in Ambient Air and Offgas of Nonmetal Material

    Institute of Scientific and Technical Information of China (English)

    于芳; 何正杰; 姜洁; 何新


    We have built GC/MS - SIM analysis method for benzene in ambient air and offgas of nonmetal material and determined the concentration of benzene in the offgas of a kind of nonmetal material with external standard quantity method.

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

    Directory of Open Access Journals (Sweden)

    Cuiqin Wu


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

  17. Alkylation reaction by the 2-chloropropane of benzene on the hyper saline element processes alumina catalyst; Koenso shori arumina shokubaijo deno benzen no 2-kuroropuropan ni yoru arukiruka hanno

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, Kazuhiro; Saeki, Takayuki; Sawada, Tetsuro; Shobu, Akinori


    The semibatch reactor was used at atmospheric pressure, 273K in respect of isopropyl reaction by 2-chloropropane (2CP) of benzene on aluminia catalyst (AmLSA) chlorinated in the high temperature. The AmLSA catalyst showed the activity, which was higher than the AlCl{sub 3} catalyst. Main products were isopropyl benzene (IPB) and para - diisopropyl benzene (dj-IPB) - 1,3,5-triisopropyl benzene (tri-IPB) and, and the generation of 4 substitutes was as a trace. Product composition at 2CP 100% conversion ratio is IPB 76%, di-IPB I9%, tri-IPB 5% Di-IPB in the isopropyl reaction of IPB be 82%, tri-IPB It was 18%. The catalyst was perfectly toxified, even if it is deaerated at the temperature of pyridine adsorption post 573K or less, and it began to recover in the de-aeration of 673K, and it recovered after the de-aeration at 873K to active 43% before the toxification. It was concluded, when the reaction perfectly stops, when the catalyst is removed from system of reaction, and when the elution of the active species has not been generated. In comparison with the result of result of the superscription and alkylation reaction by 1 - chloropropane (ICP) and isopropyl reaction by the aluminum chloride catalyst, the reaction on the AmLSA catalyst was explained with that it progressed by the mechanism of the Friedel-Crafts type. (translated by NEDO)

  18. Underpotential deposition of hydrogen on benzene-modified Pt(111) in aqueous H2SO4. (United States)

    Jerkiewicz, Gregory; DeBlois, Martin; Radovic-Hrapovic, Zorana; Tessier, Jean-Pierre; Perreault, Frédéric; Lessard, Jean


    The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80 V range in aq H2SO4 + 1 mM C6H6. The C6H6 (ads) overlayer significantly changes the underpotential-deposited H (H(UPD)) and anion adsorption, and cyclic-voltammetry (CV) profiles show a sharp cathodic peak and an asymmetric anodic one in the 0.05-0.80 V potential range. The C6H6 (ads) layer blocks the (bi)sulfate adsorption but facilitates the adsorption of one monolayer of H(UPD). Cycling of the benzene-modified Pt(111) in benzene-free aq 0.05 H2SO4 from 0.05 to 0.80 V results in a partial desorption of C6H6 (ads) and in a partial recovery of the CV profile characteristic of an unmodified Pt(111). The peak potential of the cathodic and anodic feature is independent of the scan rate, s (10 0 to 0 kJ mol(-1) at theta(H(UPD) --> 1. The nonzero values of delta Delta G degrees testify that the adsorbing and desorbing H(UPD) adatoms interact with an energetically different substrate. The lateral interactions changed from repulsive (omega = 29 kJ mol(-1) at theta(H(UPD) --> 0) to attractive (omega = -28 kJ mol(-1) at theta(H(UPD) --> 1) as the H(UPD) coverage increases. The values of delta S degrees(ads)(H(UPD)) increase from 19 to 56 J K(-1) mol(-1), while those of delta S degrees(des)(H(UPD)) decrease from 45 to -30 J K(-1) mol(-1) with an increase of H(UPD) coverage. The values of delta H degrees(des)(H(UPD)) and delta H degrees(des)(H(UPD)) vary from 0 to 27 kJ mol(-1). The Pt(111)-H(UPD) surface bond energy at the benzene-modified Pt(111) electrode falls in the 191-218 kJ mol(-1) range and is weaker than in the case of the unmodified Pt(111) electrode in the same electrolyte.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sweeney, Lynn C. [Washington State Univ., Pullman, WA (United States)


    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

  20. Field-based and laboratory stable isotope probing surveys of the identities of both aerobic and anaerobic benzene-metabolizing microorganisms in freshwater sediment. (United States)

    Liou, J S-C; Derito, C M; Madsen, E L


    Laboratory incubations of coal-tar waste-contaminated sediment microbial communities under relatively controlled physiological conditions were used to interpret results of a field-based stable isotope probing (SIP) assay. Biodegradation activity of 13C-benzene was examined by GC/MS determination of net 13CO2 production and by GC headspace analysis of benzene loss. Key experimental variables were: the site of the assays (laboratory serum-bottle incubations and in situ field sediments), benzene concentration (10, 36 or 200 p.p.m. in laboratory assays), and physiological conditions (anaerobic with or without sulfate or nitrate additions versus aerobic headspace or the uncontrolled field). In anaerobic laboratory incubations of benzene at 10 p.p.m., greater than 60% of the substrate was eliminated within 15 days. During anaerobic incubations of 200 p.p.m. benzene (70 days), 0.9% benzene mineralization occurred. When benzene (36 p.p.m.) was added to sediment with air in the serum-bottle headspace, 14% of the initial 13C was mineralized to 13CO2 in 2.5 days. In the field experiment (178 microg 13C-benzene dosed to undisturbed sediments), net 13CO2 production reached 0.3% within 8.5 h. After isopycnic separation of 13C (heavy)-labelled DNA from the above biodegradation assays, sequencing of 13C-DNA clone libraries revealed a broad diversity of taxa involved in benzene metabolism and distinctive libraries for each biodegradation treatment. Perhaps most importantly, in the field SIP experiment the clone libraries produced were dominated by Pelomonas (betaproteobacteria) sequences similar to those found in the anaerobic 10 p.p.m. benzene laboratory experiment. These data indicate that the physiological conditions that prevail and govern in situ biodegradation of pollutants in the field may be interpreted by knowing the physiological preferences of potentially active populations.

  1. Influence of van der Waals forces on the adsorption structure of benzene on silicon studied using density functional theory

    DEFF Research Database (Denmark)

    Johnston, Karen; Kleis, Jesper; Lundqvist, Bengt


    Two different adsorption configurations of benzene on the Si(001)-(2×1) surface, the tight-bridge and butterfly structures, were studied using density functional theory. Several exchange and correlation functionals were used, including the recently developed van der Waals density functional (vdW-...

  2. Size-specific interaction of alkali metal ions in the solvation of M+-benzene clusters by Ar atoms. (United States)

    Huarte-Larrañaga, F; Aguilar, A; Lucas, J M; Albertí, M


    The size-specific influence of the M+ alkali ion (M = Li, Na, K, Rb, and Cs) in the solvation process of the M+-benzene clusters by Ar atoms is investigated by means of molecular dynamic simulations. To fully understand the behavior observed in M+-bz-Ar(n) clusters, solvation is also studied in clusters containing either M+ or benzene only. The potential energy surfaces employed are based on a semiempirical bond-atom decomposition, which has been developed previously by some of the authors. The outcome of the dynamics is analyzed by employing radial distribution functions, studying the evolution of the distances between the Ar atoms and the alkali ion M+ or the benzene molecule for all M+-bz-Ar(n) clusters. For all members, in the M+-bz series, the benzene molecule (bz) is found to remain strongly bound to M+ even in the presence of solvent atoms. The radial distribution functions for the heavier clusters (K+-bz, Rb+-bz, and Cs+-bz), are found to be different than for the lighter (Na+-bz and Li+-bz) ones.

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

    Directory of Open Access Journals (Sweden)

    Benjamin Edokpolo


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

  4. Remediation of groundwater contaminated with MTBE and benzene: the potential of vertical-flow soil filter systems

    NARCIS (Netherlands)

    Afferden, M. van; Rahman, K.Z.; Mosig, P.; De Biase, C.; Thullner, M.; Oswald, S.E.; Müller, R.A.


    Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long per

  5. Residential Proximity to Heavy-Traffic Roads, Benzene Exposure, and Childhood Leukemia-The GEOCAP Study, 2002-2007. (United States)

    Houot, Jennifer; Marquant, Fabienne; Goujon, Stéphanie; Faure, Laure; Honoré, Cécile; Roth, Marie-Hélène; Hémon, Denis; Clavel, Jacqueline


    Childhood leukemia may be associated with traffic-related environmental exposure to benzene, and additional data are needed. The Géolocalisation des Cancers Pédiatriques (GEOCAP) Study, a nationwide French case-control study, was designed to avoid selection bias due to differential participation and misclassification. The study compared the 2,760 childhood leukemia cases diagnosed in France between 2002 and 2007 (including 2,275 cases of acute lymphoblastic leukemia (ALL) and 418 cases of acute myeloblastic leukemia (AML)) with 30,000 contemporaneous child population controls. The residence addresses were precisely geocoded, and 3 indicators of residential proximity to traffic were considered. Estimates of benzene concentrations were also available for the Île-de-France region (including Paris). A 300-m increase in major road length within 150 m of the geocoded address was significantly associated with AML (odds ratio = 1.2, 95% confidence interval: 1.0, 1.4) but not with ALL (odds ratio = 1.0, 95% confidence interval: 0.9, 1.1), and the association was reinforced in the Île-de-France region when this indicator was combined with benzene estimates. These results, which were free from any participation bias and based on objectively determined indices of exposure, showed an increased incidence of AML associated with heavy-traffic road density near a child's home. The results support a role for traffic-related benzene exposure in the etiology of childhood AML.

  6. Correlation of fractal pore-size distribution of activatedcarbon fiber with its adsorption for low concentration benzene vapor

    Institute of Scientific and Technical Information of China (English)

    HUANG; Zhenghong; (黄正宏); KANG; Feiyu; (康飞宇); LIANG; Kaiming; (梁开明); YANG; Junbing; (杨骏兵)


    Fractal pore-size distribution K(x) is given based on J(x) function proposed by Jaronic. Activated carbon fibers (ACF) with different surface areas are characterized by using two functions mentioned above. The present work studies the fractal pore-size distribution of ACF and adsorption isotherms of nonpolar benzene vapor on ACF, and thereby reveals the correlation between them.

  7. A bench-scale constructed wetland as a model to characterize benzene biodegradation processes in freshwater wetlands. (United States)

    Rakoczy, Jana; Remy, Benjamin; Vogt, Carsten; Richnow, Hans H


    In wetlands, a variety of biotic and abiotic processes can contribute to the removal of organic substances. Here, we used compound-specific isotope analysis (CSIA), hydrogeochemical parameters and detection of functional genes to characterize in situ biodegradation of benzene in a model constructed wetland over a period of 370 days. Despite low dissolved oxygen concentrations (98% removal), we applied CSIA to study in situ benzene degradation by indigenous microbes. Combining carbon and hydrogen isotope signatures by two-dimensional stable isotope analysis revealed that benzene was degraded aerobically, mainly via the monohydroxylation pathway. This was additionally supported by the detection of the BTEX monooxygenase gene tmoA in sediment and root samples. Calculating the extent of biodegradation from the isotope signatures demonstrated that at least 85% of benzene was degraded by this pathway and thus, only a small fraction was removed abiotically. This study shows that model wetlands can contribute to an understanding of biodegradation processes in floodplains or natural wetland systems.

  8. Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅱ. Hydrogenation of Benzene Catalyzed by MlNi5

    Institute of Scientific and Technical Information of China (English)

    安越; 陈长聘; 徐国华; 蔡官明; 王启东


    The feasibility of the hydrogenation of benzene into cyclohexane over the hydrogen storage alloy MlNi5 catalyst was studied in the temperature range of 402~463 K. The results show that the reaction order is zero and the energy of activation is 28.9 kJmol-1.

  9. Thermal diffusion factor for carbon tetrachloride-cyclohexane and benzene-n-heptane mixtures from thermogravitational column separation

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, J.L.; Madariaga, J.A.; Santamaria, C.M.; Saviron, J.M.; Carrion, J.A.


    Measurements of the separation of liquid mixtures of n-heptane/benzene and carbon tetrachloride/cyclohexane in a thermogravitational column are reported. The results show that thermal diffusion columns of little mechanical precision can furnish suitable thermal diffusion factors when the diffusion coefficient, viscosity, density, and compressibility factor for the mixture are known. 23 references, 3 figures, 1 table.

  10. Removal of benzene and toluene in horizontal-flow anaerobic immobilized biomass reactor (HAIBR) in the presence of sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Cattony, E.B.M.; Chinalia, F.A.; Adorno, M.A.T.; Moraes, E.M.; Zaiat, M.; Foresti, E.; Varesche, M.B.A. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Biological Processes Laboratory


    The removal of toluene and benzene from organic waste by microorganisms was tested in two bioreactors. Two horizontal-flow anaerobic immobilized biomass (HAIB) reactors were fed with Zinder medium to stimulate anaerobic sulfate-reducing bacteria (SRB). The chemical oxygen demand (COD) and sulfate analysis were assessed and acetic acid, toluene and benzene were analyzed in gas chromatography. Microbial communities were characterized by fluorescence, optical electron microscopy and molecular biology analysis. The HAIB reactors achieved steady state within 2 weeks following hydrocarbon compound amendments. Depletion of sulfate was achieved after this time, along with removal of toluene and benzene. The inflow COD for both reactors was more than 95 per cent. The HAIB reactor operated under sulfidogenic conditions. It was concluded that the use of benzene and toluene is an efficient and cost-effective method for treating contaminated water, particularly for tropical developing countries. The study emphasized the importance of SRB populations in bioreactors to degrade organic aromatics under oxygen reduced conditions. 10 refs., 4 figs.

  11. Nafion/SiO2 Nanocomposites: High Potential Catalysts for Alkylation of Benzene with Linear C9-C13 Alkenes

    Institute of Scientific and Technical Information of China (English)


    High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.

  12. Spectroscopic study on deuterated benzenes. I. Microwave spectra and molecular structure in the ground state

    Energy Technology Data Exchange (ETDEWEB)

    Kunishige, Sachi; Katori, Toshiharu; Baba, Masaaki, E-mail: [Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Nakajima, Masakazu; Endo, Yasuki [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902 (Japan)


    We observed microwave absorption spectra of some deuterated benzenes and accurately determined the rotational constants of all H/D isotopomers in the ground vibrational state. Using synthetic analysis assuming that all bond angles are 120°, the mean bond lengths were obtained to be r{sub 0}(C–C) = 1.3971 Å and r{sub 0}(C–H) = r{sub 0}(C–D) = 1.0805 Å. It has been concluded that the effect of deuterium substitution on the molecular structure is negligibly small and that the mean bond lengths of C–H and C–D are identical unlike small aliphatic hydrocarbons, in which r{sub 0}(C–D) is about 5 mÅ shorter than r{sub 0}(C–H). It is considered that anharmonicity is very small in the C–H stretching vibration of aromatic hydrocarbons.

  13. Solubilization of benzene, toluene, and xylene (BTX) in aqueous micellar solutions of amphiphilic imidazolium ionic liquids. (United States)

    Łuczak, Justyna; Jungnickel, Christian; Markiewicz, Marta; Hupka, Jan


    Water-soluble ionic liquids may be considered analogues to cationic surfactants with a corresponding surface activity and ability to create organized structures in aqueous solutions. For the first time, the enhanced solubility of the aromatic hydrocarbons, benzene, toluene, and xylene, in aqueous micellar systems of 1-alkyl-3-methylimidazolium chlorides was investigated. Above a critical micelle concentration, a gradual increase in the concentration of aromatic hydrocarbons in the miceller solution was observed. This phenomenon was followed by means of the molar solubilization ratio, the micellar/water partition coefficient, and the number of solubilizate molecules per IL micelle. The molar solubilization ratio for ionic liquid micelles was found to be significantly higher when compared to that of ionic surfactants of similar chain length. The incorporation of the hydrocarbon into the micelle affects also an increase of the aggregation number.

  14. Simultaneous removal of ethyl acetate, benzene and toluene with gliding arc gas discharge

    Institute of Scientific and Technical Information of China (English)

    Zheng BO; Jian-hua YAN; Xiao-dong LI; Yong CHI; Ke-fa CEN


    The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge (GA) reactor. Good decomposition efficiencies are obtained which proves that the GA is effective for the treatment of volatile organic compounds (VOCs) with either low or high concentration. A theoretical decomposition mechanism is proposed based on detection of the species in the plasma region and analysis of the decomposition by-products. This preliminary investigation reveals that the GA has potential to be applied to the treatment of exhaust air during color printing and coating works, by either direct removal or combination with activated carbon adsorption/desorption process.

  15. Effect of linear alkyl benzene sulfonate on germination of spores of the aquatic fern Ceratopteris thalictroides

    Energy Technology Data Exchange (ETDEWEB)

    Singh, J.; Devi, S. (National Botanical Research Institute, Lucknow (India))


    Validity of fern spore germination bioassays for the effects of environmental pollution was established by many researchers. Some workers studied the phytotoxicity of linear alkyl benzene sulfonate (LAS) on the spores of Diplazium esculentum and observed that LAS levels above 0.001% are toxic to fern spores. Water pollution due to synthetic detergents has been increasing continuously during the last few years due to their extensive use in domestic life, agriculture and industry. These detergents are among the most common pollutants responsible for water pollution. In view of this fact, the phytotoxicity of LAS on germination of an aquatic fern Ceratopteris thalictroides spores was studied. However, in these studies, only germination pattern was taken as index and no observations were made on the developmental stages.

  16. The effect of Ce ion substituted OMS-2 nanostructure in catalytic activity for benzene oxidation (United States)

    Hou, Jingtao; Li, Yuanzhi; Mao, Mingyang; Zhao, Xiujian; Yue, Yuanzheng


    The nanostructure of Ce doped OMS-2 plays a very important role in its catalytic property. We demonstrate by density functional theory (DFT) calculations that the unique nanostructure of the Ce ion substituted OMS-2 with Mn vacancy in the framework is beneficial for the improvement of catalytic activity, while the nanostructure of the Ce ion substituted OMS-2 without defects are detrimental to the catalytic activity. We establish a novel and facile strategy of synthesizing these unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework by hydrothermal redox reaction between Ce(NO3)3 and KMnO4 with KMnO4/Ce(NO3)3 at a molar ratio of 3 : 1 at 120 °C. Compared to pure OMS-2, the produced catalyst of Ce ion substituted OMS-2 ultrathin nanorods exhibits an enormous enhancement in the catalytic activity for benzene oxidation, which is evidenced by a significant decrease (ΔT50 = 100 °C, ΔT90 = 129 °C) in the reaction temperature of T50 and T90 (corresponding to the benzene conversion = 50% and 90%), which is considerably more efficient than the expensive supported noble metal catalyst (Pt/Al2O3). We combine both theoretical and experimental evidence to provide a new physical insight into the significant effect due to the defects induced by the Ce ion substitution on the catalytic activity of OMS-2. The formation of unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework leads to a significant enhancement of the lattice oxygen activity, thus tremendously increasing the catalytic activity.The nanostructure of Ce doped OMS-2 plays a very important role in its catalytic property. We demonstrate by density functional theory (DFT) calculations that the unique nanostructure of the Ce ion substituted OMS-2 with Mn vacancy in the framework is beneficial for the improvement of catalytic activity, while the nanostructure of the Ce ion substituted OMS-2 without defects are detrimental to the catalytic activity. We establish a novel

  17. Alkylation of benzene with propylene catalyzed by FeCl3-Chloropyridine ionic liquid

    Institute of Scientific and Technical Information of China (English)

    SUN Xuewen; ZHAO Suoqi; LI Hui


    Alkylation of benzene with propylene was carried out with FeCl3-chloro-butyl-pyridine(FeCl3-[bpc])ionic liquid as catalyst to obtain cumene.Significant improvements in propylene conversion and cumene selectivity under mild reaction conditions were attained by modification of the catalyst with HCl.Under 20℃,0.1 MPa,reaction time 5 min,increase from 83.60%to 100.00%and selectivity of cumene can increase from 90.86%to 98.47%.If reaction is carried out in following two stages,the result will be very good.At the initial stage of the reaction,alkylation is the main reaction and a higher conversion of propylene is obtained at a lower temperature.At the later stage of the reaction,transalkylation is the main reaction and selectivity to cumene can be increased by appropriately raising the reaction temperature.

  18. Isopropylation of benzene with 2-propanol over substituted large pore aluminophosphate-based molecular sieves

    Indian Academy of Sciences (India)

    K Joseph Antony Raj; V R Vijayaraghavan


    Large pore aluminophosphate-based molecular sieves like AlPO4-5, MAPO-5, MnAPO-5 and ZAPO-5 were synthesised hydrothermally using triethylamine as a structure directing agent. These materials were characterised by X-ray diffraction (XRD), 27Al and 31P MAS-NMR, ICP-MS, -butylamine- TPD, BET and SEM. The catalytic performance of these materials was tested for isopropylation of benzene with 2-propanol at 250, 300, 350 and 400°C. The products were cumene, -DIPB (-diisopropylbenzene) and -DIPB (-diisopropylbenzene). MnAPO-5 was found to be more active than the other catalysts. Maximum conversion (20%) was noted at 350°C over MnAPO-5. The selectivity to DIPB was found to decrease with time on stream but the selectivity to cumene showed an increase after 3 h of time on stream.

  19. (E)-4-[4-(Diethyl-amino)-benzyl-idene-ammonio]-benzene-sulfonate. (United States)

    Ruanwas, Pumsak; Chantrapromma, Suchada; Fun, Hoong-Kun


    The title compound, C(17)H(20)N(2)O(3)S, synthesised from sulfanilic acid and 4-diethyl-amino-benzaldehyde, crystallized out as a zwitterion with the central N atom protonated. The zwitterion exists in an E conformation with respect to the C=N double bond. The dihedral angle between the benzene rings is 37.57 (5)°. In the crystal, the zwitterions are linked into a tape along the a axis by N-H⋯O hydrogen bonds. The crystal structure is further stabilized by weak C-H⋯O inter-actions and π-π inter-actions with a centroid-centroid distance of 3.8541 (6) Å. An O⋯O [2.8498 (11) Å] short contact is present.

  20. 1,4-Bis{(+-(S-[1-(1-naphthylethyl]iminomethyl}benzene

    Directory of Open Access Journals (Sweden)

    Armando Espinosa Leija


    Full Text Available The title compound, C32H28N2, is a chiral bis-imine in which both imine groups display the common E configuration. The naphthyl groups present different orientations with respect to the central core, as reflected in the dihedral angles of 21.4 (2 and 78.83 (14° between the benzene and naphthyl mean planes, thus the highest possible C2 local molecular symmetry is not attained. This C1 molecular conformation allows multiple C—H...π intermolecular contacts involving all aromatic rings, while no π–π interactions are available for the stabilization of the crystal structure. The resulting packing structure is based on molecules stacked along [100].

  1. Corrosion inhibition efficiency of linear alkyl benzene derivatives for carbon steel pipelines in 1M HCl

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh


    Full Text Available Linear alkyl benzene sulfonic acid (L and three of its ester derivatives (L1, L2, L3 were prepared, followed by quaternization of these esters (L1Q, L2Q, L3Q. The corrosion inhibition effect on carbon steel in 1 M HCl was studied using weight loss and potentiodynamic polarization measurements. The adsorption of the inhibitors on carbon steel surface obeyed the Langmuir’s adsorption isotherm. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy (ΔH∗, entropy (ΔS∗ of activation, adsorption–desorption equilibrium constant (Kads, standard free energy of adsorption (ΔGoads, heat (ΔHoads, and entropy of adsorption (ΔSoads were calculated to elaborate the corrosion inhibition mechanism.

  2. Bis[(E-3-(4-methoxyphenylprop-2-enoato]triphenylantimony(V benzene monosolvate

    Directory of Open Access Journals (Sweden)

    Evgeny V. Chuprunov


    Full Text Available The asymmetric unit of the title compound, [Sb(C6H53(C10H9O32]·C6H6, contains one organometallic molecule and one benzene molecule that is disordered over two sets of sites with an occupancy ratio of 0.556 (15:0.444 (15. The SbV atom is in a distorted trigonal–bipyramidal environment with the carboxylate O atoms in axial positions and phenyl C atoms in the equatorial plane. As a result of additional Sb...O interactions, one of the C—Sb—C angles is widened to 140.19 (6°.

  3. Optimal Hubbard models for materials with nonlocal Coulomb interactions: graphene, silicene, and benzene. (United States)

    Schüler, M; Rösner, M; Wehling, T O; Lichtenstein, A I; Katsnelson, M I


    To understand how nonlocal Coulomb interactions affect the phase diagram of correlated electron materials, we report on a method to approximate a correlated lattice model with nonlocal interactions by an effective Hubbard model with on-site interactions U(*) only. The effective model is defined by the Peierls-Feynman-Bogoliubov variational principle. We find that the local part of the interaction U is reduced according to U(*)=U-V[over ¯], where V[over ¯] is a weighted average of nonlocal interactions. For graphene, silicene, and benzene we show that the nonlocal Coulomb interaction can decrease the effective local interaction by more than a factor of 2 in a wide doping range.

  4. A Durable Catalyst for Vapor Phase Nitration of Benzene with Nitric Acid

    Institute of Scientific and Technical Information of China (English)


    Experimental results in this work demonstrate that PW12-H2SO4/SiO2 catalyst is a good and durable catalyst for vapor phase nitration of benzene to nitrobenzene (NB) using 65% nitric acid at normal pressure. It retains the advantages of using H2SO4 as catalyst and the addition of phosphotungstic acid holds back the effusion of sulfuric acid. This new catalyst keeps high activity (the conversion of HNO3 is more than 92%), high selectivity of NB (more than 97%) and high space time yield (STY 1.5 kg NB/kg cat.h) even after 150 h on stream, under condition of 423 K, SV=3200 ml/g h.

  5. Friction behavior of 304 stainless steel of varying hardness lubricated with benzene and some benzyl structures (United States)

    Buckley, D. H.


    The lubricating properties of some benzyl and benzene structures were determined by using 304 stainless steel surfaces strained to various hardness. Friction coefficients and wear track widths were measured with a Bowden-Leben type friction apparatus by using a pin-on-disk specimen configuration. Results obtained indicate that benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol resulted in the lowest friction coefficients for 304 stainless steel, while benzyl ether provided the least surface protection and gave the highest friction. Strainhardening of the 304 stainless steel prior to sliding resulted in reduced friction in dry sliding. With benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol changes in 304 stainless steel hardness had no effect upon friction behavior.

  6. Differences in the sublimation energy of benzene and hexahalogenbenzenes are caused by dispersion energy. (United States)

    Trnka, Jakub; Sedlak, Robert; Kolář, Michal; Hobza, Pavel


    The crystals of benzene and hexahalogenbenzenes have been studied by means of the density functional theory augmented by an empirical dispersion correction term as well as by the symmetry-adapted perturbation theory. In order to elucidate the nature of noncovalent binding, pairwise interactions have been investigated. It has been demonstrated that the structures of dimers with the highest stabilization energy differ notably along the crystals. It has been shown that the differences in the experimental sublimation energies might be attributed to the dispersion interaction. To our surprise, the dihalogen bonding observed in the hexachloro- and hexabromobenzenes plays a rather minor role in structure stabilization because it is energetically comparable with the other binding motifs. However, the dihalogen bond is by far the most frequent binding motif in hexachloro- and hexabromobenzenes.

  7. Effects of valence, geometry and electronic correlations on transport in transition metal benzene sandwich molecules (United States)

    Karolak, M.; Jacob, D.


    We study the impact of the valence and the geometry on the electronic structure and transport properties of different transition metal-benzene sandwich molecules bridging the tips of a Cu nanocontact. Our density-functional calculations show that the electronic transport properties of the molecules depend strongly on the molecular geometry which can be controlled by the nanocontact tips. Depending on the valence of the transition metal center certain molecules can be tuned in and out of half-metallic behaviour facilitating potential spintronics applications. We also discuss our results in the framework of an Anderson impurity model, indicating cases where the inclusion of local correlations alters the ground state qualitatively. For Co and V centered molecules we find indications of an orbital Kondo effect.


    Directory of Open Access Journals (Sweden)

    L. B. Brondani


    Full Text Available Abstract Extractive distillation processes with N-formylmorpholine (NFM are used industrially to separate benzene from six carbon non-aromatics. In the process studied in this work, the stream of interest consists of nearly 20 different hydrocarbons. A new set of NRTL parameters was correlated based on literature experimental data. Both vapor-liquid equilibrium as well as infinite dilution activity coefficient data were taken into account; missing parameters were estimated with the UNIFAC group contribution model. The extractive distillation process was simulated using ASPEN Plus®. Very good agreement with plant data was obtained. The influences of the main operational parameters, solvent to feed ratio and solvent temperature, were studied. Theoretical optimum operating values were obtained and can be implemented to improve the industrial process. Extreme static sensitivity with respect to reboiler heat was observed, indicating that this can be the source of instabilities.

  9. Infrared study of the polymorphism of 4,4'-di-n-butyloxyazoxy-benzene. (United States)

    bamezai, R. K.; Godlewska, M.; Kocot, A.; Sciesinski, J.


    Infrared spectra in the frequency range 250 - 700 cm -1 are presented for 4,4'-di-n-butyloxyazoxybenzene as a function of temperature. All the phases known from the adiabatic calorimetry measurements were obtained. there are significant changes in the spectra at the phase IV - phase III transition and only very slight changes of the intensities of some bands are observed at the phase III - phase II transition. The transition between phase II and I is manifested solely by a jump increase of the background. On melting to the nematic phase again the spectra change distinctly. The changes observed in the spectra seem to indicate that apart from the configurational changes of the lateral chaines reported in literature, also the the angle between the benzene rings changes at the phase transitions.

  10. Structural relaxation and mode coupling in a non-glassforming liquid: depolarized light scattering in benzene

    Energy Technology Data Exchange (ETDEWEB)

    Wiebel, Sabine [Physik-Department E13, Technische Universitaet Muenchen, Garching (Germany); Wuttke, Joachim [Physik-Department E13, Technische Universitaet Muenchen, Garching (Germany) and Siemens AG, ICN ON RD AT 1, Munich (Germany)]. E-mail:


    We have measured depolarized light scattering in liquid benzene over the whole accessible temperature range and over four decades in frequency. Between 40 and 180 GHz we find a susceptibility peak due to structural relaxation. This peak shows stretching and time-temperature scaling as known from alpha relaxation in glass-forming materials. A simple mode-coupling model provides consistent fits of the entire data set. These qualitative and quantitative results show that structural relaxation in ordinary liquids and alpha relaxation in glass-forming materials are one and the same physical process. Thus, a deeper understanding of equilibrium liquids is reached by applying concepts that were originally developed in the context of glass-transition research. (author)

  11. Tetrachlorido[(diphenylphosphinodiphenylphosphine oxide-κO]zirconium(IV benzene monosolvate

    Directory of Open Access Journals (Sweden)

    Takahiko Ogawa


    Full Text Available In the title centrosymmetric mononuclear ZrIV compound, [ZrCl4{P(O(C6H52P(C6H52}2]·C6H6, the central ZrIV ion is coordinated by two O atoms from two symmetry-related (diphenylphosphinodiphenylphosphine ligands and four Cl atoms in a distorted octahedral geometry with the four Cl atoms in the equatorial positions. The molecule lies about a center of inversion and the benzene solvent molecule about another center of inversion. The P=O bond [1.528 (2 Å] is slightly longer than a typical P=O double bond (average 1.500 .

  12. 1-Nitro-4-(4-nitro-phen-oxy)benzene: a second monoclinic polymorph. (United States)

    Naz, Mehwish; Akhter, Zareen; McKee, Vickie; Nadeem, Arif


    In the title compound, C12H8N2O5, the aromatic rings are inclined to one another by 56.14 (7)°. The nitro groups are inclined by to the benzene rings to which they are attached by 3.86 (17) and 9.65 (15)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming a three-dimensional structure. The title compound is a new monoclinic polymorph, crystallizing in space group P21/c. The first polymorph crystallized in space group C2/c and the mol-ecule possesses twofold rotation symmetry. Two low-temperature structures of this polymorph (150 K and 100 K, respectively) have been reported [Meciarova et al. (2004). Private Communication (refcode IXOGAD). CCDC, Cambridge, England, and Dey & Desiraju (2005). Chem. Commun. pp. 2486-2488].

  13. Some new progress on the light absorption properties of linear alkyl benzene solvent

    CERN Document Server

    Yu, Guang-You; Huang, Ai-Zhong; Yu, Lei; Loh, Chang-Wei; Wang, Wen-Wen; Qian, Zhi-Qiang; Yang, Hai-Bo; Huang, Huang; Xu, Zong-Qiang; Zhu, Xue-Yuan; Xu, Bin; Qi, Ming


    Linear alkyl benzene (LAB) will be used as the solvent of a liquid scintillator mixture for the JUNO antineutrino experiment in the near future. Its light absorption property should therefore be understood prior to its effective use in the experiment. Attenuation length measurements at a light wavelength of 430 nm have been performed on samples of LAB prepared for the purpose of the JUNO experiment. Inorganic impurities in LAB have also been studied for their possibilities of light absorption in our wavelength of interest. In view of a tentative plan by the JUNO collaboration to utilize neutron capture with hydrogen in the detector, we have also presented in this work, a study on the carbon-hydrogen ratio and the relationship thereof with the attenuation length of the samples.

  14. Theoretical studies on the structures and detonation properties of nitramine explosives containing benzene ring. (United States)

    Zhao, GuoZheng; Lu, Ming


    The nitramine compounds containing benzene ring were optimized to obtain their molecular geometries and electronic structures at DFT-B3LYP/6-31+G(d) level. The theoretical molecular density (ρ), heat of formation (HOF), energy gap (ΔE(LUMO-HOMO)), charge on the nitro group (-Q(NO2)), detonation velocity (D) and detonation pressure (P), estimated using Kamlet-Jacobs equations, showed that the detonation properties of these compounds were excellent. It is found that there are good linear relationships between density, heat of formation, detonation velocity, detonation pressure and the number of nitro group. The simulation results reveal that molecule G performs similarly to famous explosive HMX, and molecule H outperforms HMX. According to the quantitative standard of energetics as an HEDC (high energy density compound), molecule H essentially satisfies this requirement. These results provide basic information for molecular design of novel high energetic density compounds.

  15. Charged vanadium-benzene multidecker clusters: DFT and quantum Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Tokár, K.; Derian, R. [Institute of Physics, CCMS, Slovak Academy of Sciences, 84511 Bratislava (Slovakia); Mitas, L. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Štich, I., E-mail: [Institute of Physics, CCMS, Slovak Academy of Sciences, 84511 Bratislava (Slovakia); Ruprecht A. Institute of Technology, Bratislava (Slovakia)


    Using explicitly correlated fixed-node quantum Monte Carlo and density functional theory (DFT) methods, we study electronic properties, ground-state multiplets, ionization potentials, electron affinities, and low-energy fragmentation channels of charged half-sandwich and multidecker vanadium-benzene systems with up to 3 vanadium atoms, including both anions and cations. It is shown that, particularly in anions, electronic correlations play a crucial role; these effects are not systematically captured with any commonly used DFT functionals such as gradient corrected, hybrids, and range-separated hybrids. On the other hand, tightly bound cations can be described qualitatively by DFT. A comparison of DFT and quantum Monte Carlo provides an in-depth understanding of the electronic structure and properties of these correlated systems. The calculations also serve as a benchmark study of 3d molecular anions that require a balanced many-body description of correlations at both short- and long-range distances.

  16. Synthesis of highly selective zeolite topology molecular sieve for adsorption of benzene gas (United States)

    Wei, Lin; Chen, Yunlin; Zhang, Baoping; Zu, Zhinan


    Shangdong fly ash (SFA), Fangshan fly ash (FFA) and Heilongjiang fly ash (HFA) were selected as the raw materials to be used for synthesis of highly selective zeolite topology molecular sieve. Twice foaming method was studied in terms of synthetic zeolite. The experimental products were characterized by means of X-ray fluorescence (XRF), scanning electron microscope (SEM), X-ray diffraction (XRD), and automated surface area & pore size analyser. The results indicated that 10 M NaOH was chosen as modification experiment condition to process SFA. Crystallization temperature and time were 140 °C and 8 h, respectively. Zeolite topology molecular sieve was prepared with Si/Al molar ratio of 7.9, and its adsorption ratio of benzene gas was up to 66.51%.

  17. Substituent effects on the second ionization energies of hydroxy- and methoxy benzenes (United States)

    Roithová, Jana; Schröder, Detlef


    The second ionization energies of phenol and the isomeric dihydroxybenzenes as well as their methyl ethers are determined by means of charge-stripping mass spectrometry. Compared to the parent molecule benzene, introduction of a hydroxy substituent lowers the second ionization energy by ca. 0.6 eV, whereas a methoxy substituent exerts a much more pronounced effect of about 1.6 eV. With regard to disubstitution, the effects behave almost completely additive for the para-derivatives, whereas the ortho-compounds are stabilized only about half that much by the second substituent, and for the meta-derivatives the influence of a second donor substituent is even smaller. The trends observed highlight the role of quinoid resonance structures for the stabilization of the dicationic compounds.

  18. Catalytic ozone oxidation of benzene at low temperature over MnOx/Al-SBA-16 catalyst. (United States)

    Park, Jong Hwa; Kim, Ji Man; Jin, Mingshi; Jeon, Jong-Ki; Kim, Seung-Soo; Park, Sung Hoon; Kim, Sang Chai; Park, Young-Kwon


    The low-temperature catalytic ozone oxidation of benzene was investigated. In this study, Al-SBA-16 (Si/Al = 20) that has a three-dimensional cubic Im3m structure and a high specific surface area was used for catalytic ozone oxidation for the first time. Two different Mn precursors, i.e., Mn acetate and Mn nitrate, were used to synthesize Mn-impregnated Al-SBA-16 catalysts. The characteristics of these two catalysts were investigated by instrumental analyses using the Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. A higher catalytic activity was exhibited when Mn acetate was used as the Mn precursor, which is attributed to high Mn dispersion and a high degree of reduction of Mn oxides formed by Mn acetate than those formed by Mn nitrate.

  19. Catalytic oxidation of benzene with ozone over nanoporous Mn/MCM-48 catalyst. (United States)

    Park, Jong-Hwa; Jurng, Jongsoo; Bae, Gwi-Nam; Park, Sung Hoon; Jeon, Jong-Ki; Kim, Sang Chai; Kim, Ji Man; Park, Young-Kwon


    The catalytic oxidation of a representative volatile organic compound, benzene, with ozone at a low temperature was investigated. A nanoporous MCM-48 material with a high specific surface area was used as the support for the catalytic oxidation for the first time. Mn, which has high activity at a low temperature, was used as the metal catalyst. To examine the effect of the Mn precursor, MCM-48 was impregnated with two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were analyzed by Brunauer Emmett Teller surface area, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. MCM-48 impregnated with Mn acetate showed higher catalytic activity than MCM-48 impregnated with Mn nitrate. This result was attributed to the better dispersion within nanoporous MCM-48 and higher oxygen mobility of Mn oxides produced by Mn acetate. The catalytic activity was also shown to depend closely on the ozone concentration.

  20. Trimethyl 3,3′,3′′-(benzene-1,3,5-triyltripropynoate

    Directory of Open Access Journals (Sweden)

    Felix Katzsch


    Full Text Available In the title compound, C18H12O6, the alkyne bonds are distorted, featuring bond angles around the C—C[triple-bond]C—C group of 173.6 (1/179.0 (1, 178.1 (1/178.4 (1 and 174.9 (1/175.9 (1°, and the ester groups make angles of 3.5 (1, 13.8 (1 and 14.5 (1° with the central benzene ring. In the crystal, molecules are connected in layers parallel to (131 by weak C—H...O hydrogen bonds, giving rise to a system of hydrogen-bonded ring motifs with graph sets R22(14 and R44(22. The layers are linked by C—H...O and C—H...π contacts.