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

International Nuclear Information System (INIS)

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

2012-01-01

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

Treatment of Benzene and n-Hexane Mixtures in Trickle-Bed Air Biofilters.

Science.gov (United States)

Hassan, Ashraf Aly; Sorial, George A

2011-02-01

Trickle-bed air biofilters (TBABs) are suitable for treatment of hydrophilic volatile organic compounds, but they pose a challenge for hydrophobic compounds. Three laboratory-scale TBABs were used for the treatment of an airstream contaminated with different ratios of n-hexane and benzene mixtures. The ratios studied were 1:1, 2:1, and 1:3 n-hexane:benzene by volume. Each TBAB was operated at a pH of 4 and a temperature of 20 °C. The use of acidic-buffered nutrient solution was targeted for changing the microorganism consortium to fungi as the main biodegradation element. The experimental plan was designed to investigate the long-term performance of the TBABs with an emphasis on different mixture loading rates, removal efficiency with TBAB depth, volatile suspended solids, and carbon mass balance closure. n-Hexane loading rate was kept constant in the TBABs for comparison reasons and ranged from 4 to 22 g/(m 3 .hr). Corresponding benzene loadings ranged from 4 to 43 g/(m 3 .hr). Generally, benzene behavior in the TBAB was superior to that of n-hexane because of its higher solubility. n-Hexane showed improved performance in the 2:1 mixing ratio as compared with the other two ratios. [Box: see text].

Benzene: questions and answers

International Nuclear Information System (INIS)

1999-01-01

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

Solubility constraints affecting the migration of selenium through the cementitious backfill of a geological disposal facility

Energy Technology Data Exchange (ETDEWEB)

Felipe-Sotelo, M., E-mail: m.felipe-sotelo@lboro.ac.uk; Hinchliff, J.; Evans, N.D.M.; Read, D.

2016-03-15

Highlights: • The availability of Ca controls the concentration of SeO{sub 3}{sup 2−} in solution. • Cellulose degradation products increase the solubility of SeO{sub 3}{sup 2−} at alkaline pH. • Selenite diffuses faster through the backfill NRVB than through fly ash cements. - Abstract: This work presents the study of the solubility of selenium under cementitious conditions and its diffusion, as SeO{sub 3}{sup 2−}, through monolithic cement samples. The solubility studies were carried out under alkaline conditions similar to those anticipated in the near-field of a cement-based repository for low- and intermediate-level radioactive waste. Experiments were conducted in NaOH solution, 95%-saturated Ca(OH){sub 2}, water equilibrated with a potential backfill material (Nirex reference vault backfill, NRVB) and in solutions containing cellulose degradation products, with and without reducing agents. The highest selenium concentrations were found in NaOH solution. In the calcium-containing solutions, analysis of the precipitates suggests that the solubility controlling phase is Ca{sub 2}SeO{sub 3}(OH){sub 2}·2H{sub 2}O, which appears as euhedral rhombic crystals. The presence of cellulose degradation products caused an increase in selenium concentration, possibly due to competitive complexation, thereby, limiting the amount of calcium available for precipitation. Iron coupons had a minor effect on selenium solubility in contrast to Na{sub 2}S{sub 2}O{sub 4}, suggesting that effective reduction of Se(IV) occurs only at E{sub h} values below −300 mV. Radial through-diffusion experiments on NRVB and in a fly ash cement showed no evidence of selenium breakthrough after one year. However, autoradiography of the exposed surfaces indicated that some migration had occurred and that selenium was more mobile in the higher porosity backfill than in the fly ash cement.

Risk factor benzene

Energy Technology Data Exchange (ETDEWEB)

Stobbe, H.

1981-01-01

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

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

International Nuclear Information System (INIS)

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

1990-01-01

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

A Customizable Chamber for Measuring Cell Migration.

Science.gov (United States)

Chowdhury, Aniqa N; Vo, Huu Tri; Olang, Sharon; Mappus, Elliott; Peterson, Brian; Hlavac, Nora; Harvey, Tyler; Dean, Delphine

2017-03-12

Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between cells, the extracellular matrix, and soluble and non-soluble chemical factors (e.g., chemoattractants). Standard methods for measuring the migration of cells, such as the Boyden chamber assay, work by counting cells on either side of a divider. These techniques are easy to use; however, they offer little geometric modification for different applications. In contrast, microfluidic devices can be used to observe cell migration with customizable concentration gradients of soluble factors 1 , 2 . However, methods for making microfluidics based assays can be difficult to learn. Here, we describe an easy method for creating cell culture chambers to measure cell migration in response to chemical concentration gradients. Our cell migration chamber method can create different linear concentration gradients in order to study cell migration for a variety of applications. This method is relatively easy to use and is typically performed by undergraduate students. The microchannel chamber was created by placing an acrylic insert in the shape of the final microchannel chamber well into a Petri dish. After this, poly(dimethylsiloxane) (PDMS) was poured on top of the insert. The PDMS was allowed to harden and then the insert was removed. This allowed for the creation of wells in any desired shape or size. Cells may be subsequently added to the microchannel chamber, and soluble agents can be added to one of the wells by soaking an agarose block in the desired agent. The agarose block is added to one of the wells, and time-lapse images can be taken of the microchannel chamber in order to quantify cell migration. Variations to this method can be made for a given application, making this method highly customizable.

DNAPL migration in a coastal plain aquifer

International Nuclear Information System (INIS)

DiGuiseppi, W.H.; Jung, A.D.

1995-01-01

Soil and ground water at the Dover Gas Light Superfund Site, a former manufactured gas plant (1859 to 1948), are contaminated with polynuclear aromatic hydrocarbons and volatile organic compounds. Contaminants of concern include light aromatics, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), and heavy aromatics, including naphthalene, acenaphthylene, phenanthrene, and benzo(a)pyrene. Although ground-water contaminant levels are elevated near the site, only naphthalene and acenaphthylene are present within an order of magnitude of their solubility limits, indicating the possibility of dense non-aqueous phase liquids (DNAPL) in the subsurface. The unconfined Columbia Aquifer, which is characterized by interfingering and discontinuous sand, silt, and clay Coastal Plain deposits, overlies a clay aquitard at a depth of 60 feet. The ground water beneath the intermediate clay horizon exhibited little or no contamination, even immediately downgradient from the site. The relationship between the more permeable granular sand horizons and the less permeable interfingering clay zones controls the migration of both the aqueous-phase contamination and the DNAPL. A detailed horizontal and vertical characterization of the subsurface stratigraphy was critical to the accurate interpretation of the extent and magnitude of contamination and the identification and delineation of DNAPL zones

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

Directory of Open Access Journals (Sweden)

Zhengjun Zhang

2011-12-01

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

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

Science.gov (United States)

Zborowski, Krzysztof K.

2014-05-01

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

Benzene Monitor System report

International Nuclear Information System (INIS)

Livingston, R.R.

1992-01-01

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

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

International Nuclear Information System (INIS)

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

1991-01-01

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

PROCESS SIMULATION OF BENZENE SEPARATION COLUMN OF LINEAR ALKYL BENZENE (LABPLANT

Directory of Open Access Journals (Sweden)

Zaid A. AbdelRahman

2013-05-01

Full Text Available       CHEMCAD process simulator was used for the analysis of existing benzene separation column in LAB plant(Arab Detergent Company/Beiji-Iraq.         Simulated column performance curves were constructed. The variables considered in this study are the thermodynamic model option, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates compositions, were constructed. Four different thermodynamic models options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.            For Benzene Column (32 real stages, feed stage 14, the simulated results show that bottom temperature above 200 oC the weight fractions of top components, except benzene, increases sharply, where as benzene top weight fraction decreasing sharply. Also, feed temperature above 180 oC  shows same trends. The column profiles remain fairly constant from tray 3 (immediately below condenser to tray 10 (immediately above feed and from tray 15 (immediately below feed to tray 25 (immediately above reboiler. Simulation of the benzene separation column in LAB production plant using CHEMCAD simulator, confirms the real plant operation data. The study gives evidence about a successful simulation with CHEMCAD.

Pure Phase Solubility Limits: LANL

International Nuclear Information System (INIS)

C. Stockman

2001-01-01

, complex stability constants, and redox potentials for radionuclides in different oxidation states, form the underlying database to be used for those calculations. The potentially low solubilities of many radionuclides in natural waters constitute the first barrier for their migration from the repository into the environment. Evaluation of this effect requires a knowledge of the site-specific water chemistry and the expected spatial and temporal ranges of its variability. Quantitative determinations of radionuclide solubility in waters within the range of chemistry must be made. Speciation and molecular complexation must be ascertained to interpret and apply solubility results. The solubilities thus determined can be used to assess the effectiveness of solubility in limiting radionuclide migration. These solubilities can also be used to evaluate the effectiveness of other retardation processes expected to occur once dissolution of the source material and migration begin. Understanding the solubility behavior of radionuclides will assist in designing valuable sorption experiments that must be conducted below the solubility limit since only soluble species participate in surface reactions and sorption processes. The present strategy for radionuclide solubility tasks has been to provide a solubility model from bulk-experiments that attempt to bracket the estimate made for this Analysis and Modeling Report (AMR) of water conditions on site. The long-term goal must be to develop a thermodynamic database for solution speciation and solid-state determination as a prerequisite for transport calculations and interpretation of empirical solubility data. The model has to be self-consistent and tested against known solubility studies in order to predict radionuclide solubilities over the continuous distribution ranges of potential water compositions for performance assessment of the site. Solubility studies upper limits for radionuclide concentrations in natural waters. The

Pure Phase Solubility Limits: LANL

Energy Technology Data Exchange (ETDEWEB)

C. Stockman

2001-01-26

products, complex stability constants, and redox potentials for radionuclides in different oxidation states, form the underlying database to be used for those calculations. The potentially low solubilities of many radionuclides in natural waters constitute the first barrier for their migration from the repository into the environment. Evaluation of this effect requires a knowledge of the site-specific water chemistry and the expected spatial and temporal ranges of its variability. Quantitative determinations of radionuclide solubility in waters within the range of chemistry must be made. Speciation and molecular complexation must be ascertained to interpret and apply solubility results. The solubilities thus determined can be used to assess the effectiveness of solubility in limiting radionuclide migration. These solubilities can also be used to evaluate the effectiveness of other retardation processes expected to occur once dissolution of the source material and migration begin. Understanding the solubility behavior of radionuclides will assist in designing valuable sorption experiments that must be conducted below the solubility limit since only soluble species participate in surface reactions and sorption processes. The present strategy for radionuclide solubility tasks has been to provide a solubility model from bulk-experiments that attempt to bracket the estimate made for this Analysis and Modeling Report (AMR) of water conditions on site. The long-term goal must be to develop a thermodynamic database for solution speciation and solid-state determination as a prerequisite for transport calculations and interpretation of empirical solubility data. The model has to be self-consistent and tested against known solubility studies in order to predict radionuclide solubilities over the continuous distribution ranges of potential water compositions for performance assessment of the site. Solubility studies upper limits for radionuclide concentrations in natural waters. The

Differences in the metabolism and disposition of inhaled [3H]benzene by F344/N rats and B6C3F1 mice

International Nuclear Information System (INIS)

Sabourin, P.J.; Bechtold, W.E.; Birnbaum, L.S.; Lucier, G.; Henderson, R.F.

1988-01-01

Benzene is a potent hematotoxin and has been shown to cause leukemia in man. Chronic toxicity studies indicate that B6C3F1 mice are more susceptible than F334/N rats to benzene toxicity. The purpose of the studies presented in this paper was to determine if there were metabolic differences between F344/N rats and B6C3F1 mice which might be responsible for this increased susceptibility. Metabolites of benzene in blood, liver, lung, and bone marrow were measured during and following a 6-hr 50 ppm exposure to benzene vapor. Hydroquinone glucuronide, hydroquinone, and muconic acid, which reflect pathways leading to potential toxic metabolites of benzene, were present in much greater concentrations in the mouse than in rat tissues. Phenylsulfate, a detoxified metabolite, and an unknown water-soluble metabolite were present in approximately equal concentrations in these two species. These results indicate that the proportion of benzene metabolized via pathways leading to the formation of potentially toxic metabolites as opposed to detoxification pathways was much higher in B6C3F1 mice than in F344 rats, which may explain the higher susceptibility of mice to benzene-induced hematotoxicity and carcinogenicity

Benzene formation in electronic cigarettes.

Directory of Open Access Journals (Sweden)

James F Pankow

Full Text Available The heating of the fluids used in electronic cigarettes ("e-cigarettes" used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen from e-cigarette fluids containing propylene glycol (PG, glycerol (GL, benzoic acid, the flavor chemical benzaldehyde, and nicotine.Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice, and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG and glycerol (GL, and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

Synthesis of disodium [benzene-U-{sup 14}C]-(4-chlorophenylthio)methylenediphosphonate, [benzene-U-{sup 14}C]-tiludronate

Energy Technology Data Exchange (ETDEWEB)

Burgos, Alain; Ellames, G.J. [Alnwick Research Centre (United Kingdom). Dept. of Metabolism and Pharmacokinetics

1995-12-31

Disodium [benzene-U-{sup 14}C]-(4-chlorophenylithio)methylenediphosphonate, [benzene-{sup 14}C]-Tiludronate, 2, has been prepared in six steps from [benzene-U-{sup 14}C]-acetanilide in an overall radiochemical yield of 41%. A key step in this transformation was the efficient conversion of [U-{sup 14}C]-4-chloroaniline to [benzene-U-{sup 14}C]-4-chlorophenylthiocyanate, 5, in 83% yield by treatment of the corresponding diazonium salt, 9 with iron(111) thiocyanate. It should be noted that formation of the isomeric [benzene-U-{sup 14}C]-4-chlorophenylisothiocyanate, 11, as a byproduct, was observed in only {approx} 1% yield. (author).

Benzene and lymphohematopoietic malignancies in humans.

Science.gov (United States)

Hayes, R B; Songnian, Y; Dosemeci, M; Linet, M

2001-08-01

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

Economical benzene emission reduction

International Nuclear Information System (INIS)

Schuetz, R.

1999-01-01

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

Benzene exposures in urban areas

International Nuclear Information System (INIS)

Valerio, F.; Pala, M.; Cipolla, M.; Stella, A.

2001-01-01

Benzene exposures in urban areas were reviewed. Available data confirm that both in USA and Europe, benzene concentrations measured by fixed outdoor monitoring stations underestimate personal exposures of urban residents. Indoor sources, passive smoke and the high exposures during commuting time may explain this difference. Measures in European towns confirm that very frequently mean daily personal exposures to benzene exceed 10 μg/m 3 , current European air quality guideline for this carcinogenic compound [it

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

Energy Technology Data Exchange (ETDEWEB)

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

1992-08-01

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

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

Science.gov (United States)

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

2015-01-01

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

Benzene in Canadian gasoline : report on the effect of the benzene in gasoline regulations 2002

Energy Technology Data Exchange (ETDEWEB)

Guthrie, J. [Environment Canada, Ottawa, ON (Canada); Sabourin, R. [Carleton Univ., Ottawa, ON (Canada); Brunet, E. [Waterloo Univ., ON (Canada)

2003-11-01

The response of primary suppliers to Benzene in Gasoline Regulations was reviewed, and a summary of the effects of those regulations on the composition of gasoline in Canada in 2002 was offered. These regulations, effective July 1, 1999, were designed to provide a new approach to control fuel composition. It allowed suppliers, as a basis for compliance, the option to elect to use a yearly pool average. The benzene emission number (BEN) of gasoline was regulated, and a limit imposed on a per-litre limit for benzene at point of sale. The results indicated that reported benzene levels were significantly reduced, while aromatic levels remained practically unchanged from 1994. Since 1998, rural ambient benzene concentrations decreased by more than 32 per cent, while in urban areas, they decreased by 47 per cent over the same period. The regulated requirements for benzene concentration were met by primary suppliers in Canada in 2002 (with one exception), as were BEN levels. A number of instances of non-compliance with laboratory procedures were discovered during independent audits required for those suppliers who elected to be on on a yearly pool average. Corrective action designed to address these issues was implemented. 41 tabs., 24 figs.

Occupational exposure to benzene in South Korea.

Science.gov (United States)

Kang, Seong-Kyu; Lee, Mi-Young; Kim, Tae-Kyun; Lee, Jeong-Oh; Ahn, Yeon Soon

2005-05-30

Benzene has been used in various industries as glues or solvents in Korea. Since 1981, a preparation containing more than 1% benzene is not allowed to be manufactured, used or dealt with in the workplace, except in laboratories and in those situations benzene must be used in a completely sealed process as specified in Industrial Safety and Health Act (ISHA). Claims for compensation of hematopoietic diseases related to benzene have been rising even though the work environment has been improved. This study was conducted to assess the status of benzene exposure in different industries in Korea. We reviewed the claimed cases investigated by the Korea Occupational Safety and Health Agency (KOSHA) between 1992 and 2000. The Survey of National Work Environment Status in 1998 was analyzed to assume the number of workers and factories exposed to benzene. In 2000, six factories were investigated to evaluate benzene exposure. Personal air monitoring was performed in 61 workers and urine samples were collected from 57 workers to measure trans,trans-muconic acid (t,t-MA). Hematologic examination has performed. Thirty-four cases of hematopoietic diseases were investigated by KOSHA including eight cases of myelodysplastic syndrome and eight cases of acute myelocytic leukemia. Eight cases were accepted as related to benzene exposure. The number of workers possibly exposed to benzene can be estimated to be 196,182 workers from 6219 factories based on the database. The geometric mean of benzene in air was 0.094 (0.005-5.311) ppm. Seven samples were higher than 1 ppm but they did not go over the 10 ppm occupational exposure limit (OEL) value in Korea. The geometric mean of trans,trans-muconic acid in urine was 0.966 (0.24-2.74) mg/g creatinine. The benzene exposure level was low except in a factory where benzene was used to polymerize other chemicals. The ambient benzene from 0.1 to 1 ppm was significantly correlated with urine t,t-MA concentration (r=0.733, p<0.01). Hematologic

Mechanistic considerations in benzene physiological model development.

Science.gov (United States)

Medinsky, M A; Kenyon, E M; Seaton, M J; Schlosser, P M

1996-12-01

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 II 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.

Use of plasma C-reactive protein, procalcitonin, neutrophils,macrophage migration inhibitory factor, soluble urokinase-type plasminogen activator receptor, and soluble triggering receptor expressed on myeloid cells-1 in combination to diagnose infections: a prospective study

DEFF Research Database (Denmark)

Kofoed, Kristian; Andersen, Ove; Kronborg, Gitte

2007-01-01

the diagnostic characteristics of novel and routinely used biomarkers of sepsis alone and in combination. Methods: This prospective cohort study included patients with systemic inflammatory response syndrome who were suspected of having community-acquired infections. It was conducted in a medical emergency...... department and department of infectious diseases at a university hospital. A multiplex immunoassay measuring soluble urokinase-type plasminogen activator (suPAR) and soluble triggering receptor expressed on myeloid cells (sTREM)-1 and macrophage migration inhibitory factor (MIF) was used in parallel...... with standard measurements of C-reactive protein (CRP), procalcitonin (PCT), and neutrophils. Two composite markers were constructed – one including a linear combination of the three best performing markers and another including all six – and the area under the receiver operating characteristic curve (AUC...

Benzene and its Isomers

Indian Academy of Sciences (India)

instantly brings benzene to mind. Benzene is one of the most basic structural units of thousands of the so-called aromatic compounds, which include dyes, drugs, polymers and many more types of compounds that are very useful for our existence and progress. The whole gamut of the chemistry of aromatic compounds, ...

Elevated Atmospheric Levels of Benzene and Benzene-Related Compounds from Unconventional Shale Extraction and Processing: Human Health Concern for Residential Communities.

Science.gov (United States)

Rich, Alisa L; Orimoloye, Helen T

2016-01-01

The advancement of natural gas (NG) extraction across the United States (U.S.) raises concern for potential exposure to hazardous air pollutants (HAPs). Benzene, a HAP and a primary chemical of concern due to its classification as a known human carcinogen, is present in petroleum-rich geologic formations and is formed during the combustion of bypass NG. It is a component in solvents, paraffin breakers, and fuels used in NG extraction and processing (E&P). The objectives of this study are to confirm the presence of benzene and benzene-related compounds (benzene[s]) in residential areas, where unconventional shale E&P is occurring, and to determine if benzene[s] exists in elevated atmospheric concentrations when compared to national background levels. Ambient air sampling was conducted in six counties in the Dallas/Fort Worth Metroplex with passive samples collected in evacuated 6-L Summa canisters. Samples were analyzed by gas chromatography/mass spectrometry, with sampling performed at variable distances from the facility fence line. Elevated concentrations of benzene[s] in the atmosphere were identified when compared to U.S. Environmental Protection Agency's Urban Air Toxics Monitoring Program. The 24-hour benzene concentrations ranged from 0.6 parts per billion by volume (ppbv) to 592 ppbv, with 1-hour concentrations from 2.94 ppbv to 2,900.20 ppbv. Benzene is a known human carcinogen capable of multisystem health effects. Exposure to benzene is correlated with bone marrow and blood-forming organ damage and immune system depression. Sensitive populations (children, pregnant women, elderly, immunocompromised) and occupational workers are at increased risk for adverse health effects from elevated atmospheric levels of benzene[s] in residential areas with unconventional shale E&P.

Atmospheric benzene and toluene

International Nuclear Information System (INIS)

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

1983-01-01

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

The influence of different light quality and benzene on gene expression and benzene degradation of Chlorophytum comosum.

Science.gov (United States)

Setsungnern, Arnon; Treesubsuntorn, Chairat; Thiravetyan, Paitip

2017-11-01

Benzene, a carcinogenic compound, has been reported as a major indoor air pollutant. Chlorophytum comosum (C. comosum) was reported to be the highest efficient benzene removal plant among other screened plants. Our previous studies found that plants under light conditions could remove gaseous benzene higher than under dark conditions. Therefore, C. comosum exposure to airborne benzene was studied under different light quality at the same light intensity. C. comosum could remove 500 ppm gaseous benzene with the highest efficiency of 68.77% under Blue:Red = 1:1 LED treatments and the lowest one appeared 57.41% under white fluorescent treatment within 8 days. After benzene was uptaken by C. comosum, benzene was oxidized to be phenol in the plant cells by cytochrome P450 monooxygenase system. Then, phenol was catalyzed to be catechol that was confirmed by the up-regulation of phenol 2-monooxygenase (PMO) gene expression. After that, catechol was changed to cic, cis-muconic acid. Interestingly, cis,cis-muconic acid production was found in the plant tissues higher than phenol and catechol. The result confirmed that NADPH-cytochrome P450 reductase (CPR), cytochrome b5 (cyt b5), phenol 2-monooxygenase (PMO) and cytochrome P450 90B1 (CYP90B1) in plant cells were involved in benzene degradation or detoxification. In addition, phenol, catechol, and cis,cis-muconic acid production were found under the Blue-Red LED light conditions higher than under white fluorescent light conditions due to under LED light conditions gave higher NADPH contents. Hence, C. comosum under the Blue-Red LED light conditions had a high potential to remove benzene in a contaminated site. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Assimilation and transformation of benzene by higher plants

Energy Technology Data Exchange (ETDEWEB)

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

1974-01-01

Higher plants are capable of assimilating benzene, the molecules of which are subjected to deep chemical transformations; the products of its metabolism move along the plant. Taking part in total metabolism, carbon atoms of benzene molecules incorporate into composition of low-molecular compounds of the plant cell. The bulk of benzene carbon incorporates into composition of organic acids and a comparatively small part - into composition of amino acids. In the metabolism process benzene carbon localizes mainly in the chloroplasts. Phenol, muconic acid and CO/sub 2/ are isolated and identified from the products of benzene enzymatic oxidation. A range of benzene assimilation by higher plants is extremely wide. 9 references, 5 tables.

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

Science.gov (United States)

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

2007-01-01

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

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

Science.gov (United States)

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

2017-06-20

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

Benzene poisoning

Science.gov (United States)

... may be admitted to the hospital if the poisoning is severe. ... benzene they swallowed and how quickly they receive treatment. The ... Poisoning can cause rapid death. However, deaths have occurred ...

Investigation of Changes in Solubility Values of Some Non Impregnated Pine Species used in Water Cooling Towers

Directory of Open Access Journals (Sweden)

Murat ÖZALP

2007-01-01

Full Text Available Scotch pine (Pinus sylvestris L., Austrian black pine (Pinus nigra L. and Cyprus pine (Pinus brutia L. specimens were prepared and settled to water return system on water cooling tower. For every 3 months period’s specimens were tested solubility of hot and could water, 1% NaOH, alcohol-benzene and ethyl alcohol values were determined. For the control specimens significant color change, odour and surface softening was observed. For chemical analysis, all the solubility values were changed significantly.

Sodium tetraphenylborate solubility and dissolution rates

International Nuclear Information System (INIS)

Barnes, M.J.; Peterson, R.A.; Swingle, R.F.; Reeves, C.T.

1995-01-01

The rate of solid sodium tetraphenylborate (NaTPB) dissolution in In-Tank Precipitation salt solutions has been experimentally determined. The data indicates that the dissolution rate of solid NaTPB is a minor contributor the lag time experienced in the 1983 Salt Decontamination Demonstration Test and should not be considered as the rate determining step. Current analytical models for predicting the time to reach the composite lower flammability limit assume that the lag time is not more than 6 hours, and the data supports this assumption (i.e., dissolution by itself requires much less than 6 hours). The data suggests that another step--such as mass transport, the reaction of a benzene precursor or the mixing behavior--is the rate determining factor for benzene release to the vapor space in Tank 48H. In addition, preliminary results from this program show that the degree of agitation employed is not a significant parameter in determining the rate of NaTPB dissolution. As a result of this study, an improved equation for predicting equilibrium tetraphenylborate solubility with respect to temperature and sodium ion concentration has been determined

Benzene adsorption and oxidation on Ir(111)

NARCIS (Netherlands)

Weststrate, C.J.; Bakker, J.W.; Gluhoi, A.C.; Ludwig, W.; Nieuwenhuys, B.E.

2007-01-01

Adsorption, decompn. and oxidn. of benzene on Ir(1 1 1) was studied by high resoln. (synchrotron) XPS, temp. programmed desorption and LEED. Mol. adsorption of benzene on Ir(1 1 1) is obsd. between 170 K and 350 K. Above this temp. both desorption and decompn. of benzene take place. An ordered

Survey of benzene and aromatics in Canadian Gasoline - 1994

International Nuclear Information System (INIS)

Tushingham, M.

1996-01-01

A comprehensive database of the benzene and aromatics levels of gasoline produced in or imported into Canada during 1994, was presented. Environment Canada conducted a survey that requested refineries and importers to report quarterly on benzene and aromatics levels in gasoline. Benzene, which has been declared toxic by the Canadian Environmental Protection Act, is found in gasoline and is formed during the combustion of the aromatic components of gasoline. It was shown that benzene and aromatics levels differ regionally and seasonally. There are also variations in benzene levels between batches of gasoline produced at any one refinery. This report listed the responses to the benzene/aromatics survey. It also described the analytical procedures used to measure benzene and aromatics levels in gasoline, and provided guidelines for reporting gasoline benzene and total aromatics data. 7 tabs., 21 figs

Muonium radicals in benzene-styrene mixtures

International Nuclear Information System (INIS)

Ng, B.W.; Stadlbauer, J.W.; Walker, D.C.

1984-01-01

Muonium radicals were observed through their μ + SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10 -9 -10 -5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

A theoretical and experimental study on solubility of curatives in rubbers

NARCIS (Netherlands)

Guo, R.; Talma, Auke; Datta, Rabin; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

2009-01-01

The current study provides indications for improving the properties of dissimilar rubber blends. As solubility is a key factor for the distribution and a driving force for the migration of curatives in dissimilar rubber blends, it is of importance to have precise data of their solubilities. The

Determination of residual volatile organic compounds migrated from polystyrene food packaging into food simulant by headspace solid phase micro extraction-gas chromatography

International Nuclear Information System (INIS)

Mohd Marsin Sanagi; Ling, Susie Lu; Zalilah Nasir; Wan Aini Wan Ibrahim; Abu Naim, Ahmedy

2008-01-01

The residual styrene and other volatile organic compounds (VOCs) present in the polystyrene food packaging are of concern as these compounds have the potential to migrate into the food in contact. This work describes a method for quantitative determination of VOCs, namely styrene, toluene, ethyl benzene, iso-propylbenzene and n-propylbenzene that have migrated from polystyrene food packaging into food stimulant by gas chromatography-flame ionization detection (GC-FID). Headspace solid phase micro extraction (HS-SPME) technique was applied for migration test using water as food stimulant. The effects of extraction variables including sample volume, eluotropic strength, extraction temperature, extraction time, desorption time, sample agitation, and salt addition on the amounts of the extracted analyses were studied to obtain the optimal HS-SPME conditions. The optimized method was applied to test the VOCs migrated from polystyrene bowls and cups at storage temperatures ranging from 24 to 80 degree Celsius for 30 min. Styrene and ethyl benzene were found to migrate from the samples into the food stimulant. The migration of analyze was found to be strongly dependent upon the storage temperature. The HS-SPME is useful as an alternative method to determine the migration of VOCs from food packaging material into food stimulant. (author)

Effect of water treatment under ultrasonic irradiation on the solubilities of coals in a CS{sub 2}/NMP mixed solvent

Energy Technology Data Exchange (ETDEWEB)

Chan-Min Liu; Zhi-Min Zong; Ji-Xian Jia; Yao-Guo Huang; Hong Zhang; Bin Huang; Xian-Yong Wei [China University of Mining and Technology, Xuzhou (China). School of Chemical Engineering

2007-07-01

Five Chinese coals were subject to water treatment (WT) at 75{sup o}C under ultrasonic irradiation (UI). The resulting water-extractable fraction (WEF) in the aqueous solution was extracted with benzene. The treated and untreated coals were extracted with a CS{sub 2}/NMP mixed solvent (1:1 by vol) under UI at room temperature. The results show that only small amount of WEF is extractable with benzene and that WT increases coal solubility in the CS{sub 2}/NMP mixed solvent only to small extent. 6 refs., 2 figs., 1 tab.

A computer model for DNAPL potential migration study

International Nuclear Information System (INIS)

Yan, S.; Landry, G.R.; Tate, T.

1994-01-01

A computer model, named DNAPMIG (DNAPL Potential Migration), was developed to calculate the dense nonaqueous phase liquid (DNAPL) critical length required to initiate movement and direction of potential migration at locations within an area of interest. The model takes into consideration the potentiometric gradient, bottom structure elevation, DNAPL density, interfacial tension, contact angle, soil grain size, partitioning coefficient, effective solubility, and water saturation. The model is interfaced with SURFER graphics software to use vectors to indicate the DNAPL critical length and the potential migration direction. The potential for DNAPL existence and migration at a specific site can be estimated by relating chemical concentration in the ground water to its solubility limit and the DNAPL critical length. The possibility of vertical migration can also be determined. This model can be used to determine and compare the effectiveness of existing or alternative recovery well systems to capture a DNAPL plume or arrest its movement; to help determine optimum locations and pumping rates of recovery wells; and to help determine the optimum location of environmental borings to locate DNAPL. This paper presents two hypothetical examples and two site applications in south Louisiana

Indicators of benzene emissions and exposure in Bangkok street

International Nuclear Information System (INIS)

Leong, S.T.; Laortanakul, Preecha

2003-01-01

Ambient benzene measurements were conducted for the first time at four air monitoring sites in the Bangkok metropolitan region (BMR), from January to December 2001. Analytical results show that the mean benzene concentrations range from 42.4 μg/m 3 at the Din Daeng urban site to 15.1 μg/m 3 at the Chaeng Wattana suburban site. The monitoring results show that at a larger distance from the roadside or a higher level from the street surface, the level of benzene decreases. Analysis of the ambient benzene concentrations was carried out with reference to meteorological influences and traffic density. In traffic analysis, the combined effects of street topography and traffic flows established high impact on the overall benzene concentration in Bangkok. Statistical analysis shows good correlations of blood benzene levels and trans, trans-muconic acid with ambient benzene and demonstrated substantial exposure from traffic

Benzene exposure is associated with cardiovascular disease risk.

Directory of Open Access Journals (Sweden)

Wesley Abplanalp

Full Text Available Benzene is a ubiquitous, volatile pollutant present at high concentrations in toxins (e.g. tobacco smoke known to increase cardiovascular disease (CVD risk. Despite its prevalence, the cardiovascular effects of benzene have rarely been studied. Hence, we examined whether exposure to benzene is associated with increased CVD risk. The effects of benzene exposure in mice were assessed by direct inhalation, while the effects of benzene exposure in humans was assessed in 210 individuals with mild to high CVD risk by measuring urinary levels of the benzene metabolite trans,trans-muconic acid (t,t-MA. Generalized linear models were used to assess the association between benzene exposure and CVD risk. Mice inhaling volatile benzene had significantly reduced levels of circulating angiogenic cells (Flk-1+/Sca-1+ as well as an increased levels of plasma low-density lipoprotein (LDL compared with control mice breathing filtered air. In the human cohort, urinary levels of t,t-MA were inversely associated several populations of circulating angiogenic cells (CD31+/34+/45+, CD31+/34+/45+/AC133-, CD34+/45+/AC133+. Although t,t-MA was not associated with plasma markers of inflammation or thrombosis, t,t-MA levels were higher in smokers and in individuals with dyslipidemia. In smokers, t,t-MA levels were positively associated with urinary metabolites of nicotine (cotinine and acrolein (3-hydroxymercapturic acid. Levels of t,t-MA were also associated with CVD risk as assessed using the Framingham Risk Score and this association was independent of smoking. Thus, benzene exposure is associated with increased CVD risk and deficits in circulating angiogenic cells in both smokers and non-smokers.

The contribution of benzene to smoking-induced leukemia.

Science.gov (United States)

Korte, J E; Hertz-Picciotto, I; Schulz, M R; Ball, L M; Duell, E J

2000-04-01

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts to estimate the leukemogenic potency of benzene. Using multiple-decrement life tables, we calculated lifetime risks of total leukemia and AML deaths for never, light, and heavy smokers. We repeated these calculations, removing the effect of benzene in cigarettes based on the estimated potencies. From these life tables we determined smoking-attributable risks and benzene-attributable risks. The ratio of the latter to the former constitutes the proportion of smoking-induced cases attributable to benzene. Based on linear potency models, the benzene in cigarette smoke contributed from 8 to 48% of smoking-induced total leukemia deaths [95% upper confidence limit (UCL), 20-66%], and from 12 to 58% of smoking-induced AML deaths (95% UCL, 19-121%). The inclusion of a quadratic term yielded results that were comparable; however, potency models with only quadratic terms resulted in much lower attributable fractions--all models substantially overestimate low-dose risk, linear extrapolations from empirical data over a dose range of 10- to 100-fold resulted in plausible predictions.

Benzene monitoring at CPPI service stations

International Nuclear Information System (INIS)

Davis, C.S.

1996-01-01

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

Mechanistic considerations in benzene physiological model development.

OpenAIRE

Medinsky, M A; Kenyon, E M; Seaton, M J; Schlosser, P M

1996-01-01

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 synergis...

How Do Cells Make Decisions: Engineering Micro- and Nanoenvironments for Cell Migration

Directory of Open Access Journals (Sweden)

Siti Hawa Ngalim

2010-01-01

Full Text Available Cell migration contributes to cancer metastasis and involves cell adhesion to the extracellular matrix (ECM, force generation through the cell's cytoskeletal, and finally cell detachment. Both adhesive cues from the ECM and soluble cues from neighbouring cells and tissue trigger intracellular signalling pathways that are essential for cell migration. While the machinery of many signalling pathways is relatively well understood, how hierarchies of different and conflicting signals are established is a new area of cellular cancer research. We examine the recent advances in microfabrication, microfluidics, and nanotechnology that can be utilized to engineer micro- and nanoscaled cellular environments. Controlling both adhesive and soluble cues for migration may allow us to decipher how cells become motile, choose the direction for migration, and how oncogenic transformations influences these decision-making processes.

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Radiocarbon dating methods using benzene liquid scintillation

International Nuclear Information System (INIS)

Togashi, Shigeko; Matsumoto, Eiji

1983-01-01

The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

Benzene: a case study in parent chemical and metabolite interactions.

Science.gov (United States)

Medinsky, M A; Kenyon, E M; Schlosser, P M

1995-12-28

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 and pancytopenia, and acute myelogenous leukemia. A combination of metabolites (hydroquinone and phenol for example) is apparently 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. 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. 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. However, zonal localization of Phase I and Phase II enzymes in various regions of the liver acinus regulates 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.

In situ synthesis of silver benzene-dithiolate hybrid films

Energy Technology Data Exchange (ETDEWEB)

Brenier, Roger, E-mail: roger.brenier@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Piednoir, Agnès, E-mail: agnes.piednoir@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Bertorelle, Franck, E-mail: franck.bertorelle@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Penuelas, José, E-mail: jose.penuelas@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France); Grenet, Geneviève, E-mail: genevieve.grenet@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France)

2016-02-01

In this article, a method for in situ synthesis of silver benzene-dithiolate hybrid films is presented. Silver nanoparticles, generated on ZrO{sub 2} films, are transformed into silver benzene 1,4-dithiolate or, partially, into silver benzene 1,2-dithiolate after sample immersion in the corresponding thiol solutions. These transformations occur at room temperature owing to the catalytic action of ZrO{sub 2}. It is also shown that TiO{sub 2} in place of ZrO{sub 2} is very efficient, both for the catalytic generation of silver nanoparticles and for their further transformation in benzene 1,4-dithiolate compound. This latter semiconductor has an optical bandgap of about 3 eV and the film is made of touching nanoparticles in an amorphous state. Our work has potential applications in the electronic and photovoltaic fields. - Highlights: • A method for in situ synthesis of silver benzene-dithiolate hybrid semiconductor films is presented. • Silver nanoparticles are, first, generated on ZrO{sub 2} or on TiO{sub 2} coated silica substrates. • The samples are immersed in benzene dithiol solution for two days at room temperature. • During the immersion, the silver nanoparticles are transformed into silver benzene dithiolate. • The silver benzene dithiolate film is made of amorphous nanoparticles with a banbgap of 3 eV.

Benzene exposure and risk of non-Hodgkin lymphoma.

Science.gov (United States)

Smith, Martyn T; Jones, Rachael M; Smith, Allan H

2007-03-01

Exposure to benzene, an important industrial chemical and component of gasoline, is a widely recognized cause of leukemia, but its association with non-Hodgkin lymphoma (NHL) is less clear. To clarify this issue, we undertook a systematic review of all case-control and cohort studies that identified probable occupational exposures to benzene and NHL morbidity or mortality. We identified 43 case-control studies of NHL outcomes that recognized persons with probable occupational exposure to benzene. Forty of these 43 (93%) studies show some elevation of NHL risk, with 23 of 43 (53%) studies finding statistically significant associations between NHL risk and probable benzene exposure. We also identified 26 studies of petroleum refinery workers reporting morbidity or mortality for lymphomas and all neoplasms and found that in 23 (88%), the rate of lymphoma morbidity or mortality was higher than that for all neoplasms. A substantial healthy-worker effect was evident in many of the studies and a comprehensive reevaluation of these studies with appropriate adjustments should be undertaken. Numerous studies have also reported associations between benzene exposure and the induction of lymphomas in mice. Further, because benzene is similar to alkylating drugs and radiation in producing leukemia, it is plausible that it might also produce lymphoma as they do and by similar mechanisms. Potential mechanisms include immunotoxicity and the induction of double-strand breaks with subsequent chromosome damage resulting in translocations and deletions. We conclude that, overall, the evidence supports an association between occupational benzene exposure and NHL.

Vacuum ultraviolet photoabsorption spectroscopy of crystalline and amorphous benzene

DEFF Research Database (Denmark)

Dawes, Anita; Pascual, Natalia; Hoffmann, Soren V.

2017-01-01

We present the first high resolution vacuum ultraviolet photoabsorption study of amorphous benzene with com parisons to annealed crystalline benzene and the gas phase. Vapour deposited benzene layers w ere grow n at 25 K and annealed to 90 K under conditions pertinent to interstellaricy dust grains...

Benzene and cyclohexane separation using 1-butyl-3-methylimidazolium thiocyanate

Science.gov (United States)

Gonfa, Girma; Ismail, Marhaina; Bustam, Mohamad Azmi

2017-09-01

Cyclohexane is mainly produced by catalytic hydrogenation of benzene. Removal of unreacted benzene from the product stream is very important in this process. However, due to their close boiling points and azeotrope formation, it is very difficult to separate cyclohexane and benzene by conventional distillation. Currently, special separation processes such as processes extractive distillation is commercially used for this separation. However, this extractive distillation suffers from process complexity and higher energy consumption due to their low extractive selectivity of molecular entrainers used. The aim of the present work is to investigate the applicability of ionic liquids as entrainer in extractive distillation of benzene and cyclohexane mixture. In this study, we investigated 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) ionic liquid for separation of benzene and cyclohexane by measuring the Vapor Liquid Equilibrium data of the two components in the presence of the ionic liquid. As green and potential environmentally friendly solvents, ionic liquids have attracted increasing attention as alternative conventional entrainers in extractive distillation. Isothermal Vapor Liquid Equilibrium for the benzene + cyclohexane + [BMIM][SCN] ternary system was obtained at 353.15 K using a Head Space Gas Chromatography. The addition of [BMIM][SCN] breaks the benzene-cyclohexane azeotrope and increased the relative volatility cyclohexane to benzene in the mixture. The effect of [BMIM][SCN] on the relative volatility cyclohexane to benzene was studied at various benzene and cyclohexane compositions and solvent to feed ratios. The performance of [BMIM][SCN] was compared with typical conventional solvents, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The results show that the relative volatility of cyclohexane to benzene in the presence of [BMIM][SCN] is higher compared that of DMSO and DMF.

Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae was identified as dominant benzene degrader by Stable Isotope Probing (SIP)

NARCIS (Netherlands)

Zaan, van der B.M.; Talarico Saia, F.; Plugge, C.M.; Vos, de W.M.; Smidt, H.; Stams, A.J.M.; Langenhoff, A.A.M.; Gerritse, J.

2012-01-01

An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a

Comparison of personal air benzene and urine t,t-muconic acid as a benzene exposure surrogate during turnaround maintenance in petrochemical plants.

Science.gov (United States)

Koh, Dong-Hee; Lee, Mi-Young; Chung, Eun-Kyo; Jang, Jae-Kil; Park, Dong-Uk

2018-04-12

Previous studies have shown that biomarkers of chemicals with long half-lives may be better surrogates of exposure for epidemiological analyses, leading to less attenuation of the exposure-disease association, than personal air samples. However, chemicals with short half-lives have shown inconsistent results. In the present study, we compared pairs of personal air benzene and its short-half-life urinary metabolite trans,trans-muconic acid (t,t-MA), and predicted attenuation bias of theoretical exposure-disease association. Total 669 pairs of personal air benzene and urine t,t-MA samples were taken from 474 male workers during turnaround maintenance operations held in seven petrochemical plants. Maintenance jobs were classified into 13 groups. Variance components were calculated for personal air benzene and urine t, t-MA separately to estimate the attenuation of the theoretical exposure-disease association. Personal air benzene and urine t, t-MA showed similar attenuation of the theoretical exposure-disease association. Analyses for repeated measurements showed similar results, while in analyses for values above the limits of detection (LODs), urine t, t-MA showed less attenuation of the theoretical exposure-disease association than personal air benzene. Our findings suggest that there may be no significant difference in attenuation bias when personal air benzene or urine t,t-MA is used as a surrogate for benzene exposure.

The contribution of benzene to smoking-induced leukemia.

OpenAIRE

Korte, J E; Hertz-Picciotto, I; Schulz, M R; Ball, L M; Duell, E J

2000-01-01

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts t...

Benzene degradation in a denitrifying biofilm reactor

NARCIS (Netherlands)

Waals, van der Marcelle J.; Atashgahi, Siavash; Rocha, da Ulisses Nunes; Zaan, van der Bas M.; Smidt, Hauke; Gerritse, Jan

2017-01-01

Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more

Environmental and biological monitoring of benzene during self-service automobile refueling.

OpenAIRE

Egeghy, P P; Tornero-Velez, R; Rappaport, S M

2000-01-01

Although automobile refueling represents the major source of benzene exposure among the nonsmoking public, few data are available regarding such exposures and the associated uptake of benzene. We repeatedly measured benzene exposure and uptake (via benzene in exhaled breath) among 39 self-service customers using self-administered monitoring, a technique rarely used to obtain measurements from the general public (130 sets of measurements were obtained). Benzene exposures averaged 2.9 mg/m(3) (...

Influence of benzene emission from motorcycle on Bangkok air quality

Science.gov (United States)

Leong, Shing Tet; Muttamara, S.; Laortanakul, Preecha

This study investigated the influence of benzene concentration from motorcycle exhaust emissions on ambient air quality in Bangkok Metropolitan Region (BMR). Measurement of benzene concentration in exhaust emissions is performed on a standard test driving cycle through which each motorcycle to be tested is driven. The test result revealed that average benzene concentrations in exhaust emission for the test motorcycles ranged from 3.02 to 109.68 mg/m 3. The finding also indicated that two-stroke motorcycles emitted five times more benzene than that of four-stroke motorcycles. Four air monitoring sites were strategically established to determine the relationship between average benzene concentrations with different traffic configurations in each traffic zone of BMR during peak/non-peak hours, day/night times and weekday/weekend. The shape of the curve for benzene level usually shows two peaks corresponding to the morning and evening traffic rush or commuter rush hours. The finding shows that the mean concentrations for benzene in all monitoring stations in the ambient air for peak hours (07:00-09:00 and 16:00-18:00 h) ranged from 15.1 to 42.4 μg/m 3. For non-peak hour (11:30-15:00 h), benzene levels were found in the range 16.3-30.9 μg/m 3. It is observed that higher levels of benzene are found among roadside stations with slow moving traffic while lower levels are found among roadside stations with fast traffic movement. Additional factors such as temperature, wind speed, rainfall, etc. are also considered in this study to determine the relationship between traffic conditions and ambient benzene levels.

Modeling dissolution and volatilization of LNAPL sources migrating on the groundwater table.

Science.gov (United States)

Kim, Jeongkon; Corapcioglu, M Yavuz

2003-08-01

A vertically averaged two-dimensional model was developed to describe areal spreading and migration of light nonaqueous-phase liquids (LNAPLs) introduced into the subsurface by spills or leaks from underground storage tanks. The NAPL transport model was coupled with two-dimensional contaminant transport models to predict contamination of soil gas and groundwater resulting from a LNAPL migrating on the water table. Numerical solutions were obtained by using the finite-difference method. Simulations and sensitivity analyses were conducted with a LNAPL of pure benzene to study LNAPL migration and groundwater contamination. The model was applied to subsurface contamination by jet fuel. Results indicated that LNAPL migration were affected mostly by volatilization. The generation and movement of the dissolved plume was affected by the geology of the site and the free-product plume. Most of the spilled mass remained as a free LNAPL phase 20 years after the spill. The migration of LNAPL for such a long period resulted in the contamination of both groundwater and a large volume of soil.

Prediction of solubilities for ginger bioactive compounds in hot water by the COSMO-RS method

Science.gov (United States)

Zaimah Syed Jaapar, Syaripah; Azian Morad, Noor; Iwai, Yoshio

2013-04-01

The solubilities in water of four main ginger bioactives, 6-gingerol, 6-shogaol, 8-gingerol and 10-gingerol, were predicted using a conductor-like screening model for real solvent (COSMO-RS) calculations. This study was conducted since no experimental data are available for ginger bioactive solubilities in hot water. The σ-profiles of these selected molecules were calculated using Gaussian software and the solubilities were calculated using the COSMO-RS method. The solubilities of these ginger bioactives were calculated at 50 to 200 °C. In order to validate the accuracy of the COSMO-RS method, the solubilities of five hydrocarbon molecules were calculated using the COSMO-RS method and compared with the experimental data in the literature. The selected hydrocarbon molecules were 3-pentanone, 1-hexanol, benzene, 3-methylphenol and 2-hydroxy-5-methylbenzaldehyde. The calculated results of the hydrocarbon molecules are in good agreement with the data in the literature. These results confirm that the solubilities of ginger bioactives can be predicted using the COSMO-RS method. The solubilities of the ginger bioactives are lower than 0.0001 at temperatures lower than 130 °C. At 130 to 200 °C, the solubilities increase dramatically with the highest being 6-shogaol, which is 0.00037 mole fraction, and the lowest is 10-gingerol, which is 0.000039 mole fraction at 200 °C.

Prediction of solubilities for ginger bioactive compounds in hot water by the COSMO-RS method

International Nuclear Information System (INIS)

Jaapar, Syaripah Zaimah Syed; Iwai, Yoshio; Morad, Noor Azian

2013-01-01

The solubilities in water of four main ginger bioactives, 6-gingerol, 6-shogaol, 8-gingerol and 10-gingerol, were predicted using a conductor-like screening model for real solvent (COSMO-RS) calculations. This study was conducted since no experimental data are available for ginger bioactive solubilities in hot water. The σ-profiles of these selected molecules were calculated using Gaussian software and the solubilities were calculated using the COSMO-RS method. The solubilities of these ginger bioactives were calculated at 50 to 200 °C. In order to validate the accuracy of the COSMO-RS method, the solubilities of five hydrocarbon molecules were calculated using the COSMO-RS method and compared with the experimental data in the literature. The selected hydrocarbon molecules were 3-pentanone, 1-hexanol, benzene, 3-methylphenol and 2-hydroxy-5-methylbenzaldehyde. The calculated results of the hydrocarbon molecules are in good agreement with the data in the literature. These results confirm that the solubilities of ginger bioactives can be predicted using the COSMO-RS method. The solubilities of the ginger bioactives are lower than 0.0001 at temperatures lower than 130 °C. At 130 to 200 °C, the solubilities increase dramatically with the highest being 6-shogaol, which is 0.00037 mole fraction, and the lowest is 10-gingerol, which is 0.000039 mole fraction at 200 °C.

Study of the solubility and stability of polystyrene wastes in a dissolution recycling process

International Nuclear Information System (INIS)

Garcia, Maria Teresa; Gracia, Ignacio; Duque, Gema; Lucas, Antonio de; Rodriguez, Juan Francisco

2009-01-01

Dissolution with suitable solvents is one of the cheapest and more efficient processes for polystyrene waste management. In this work the solubility of polystyrene foams in several solvents benzene, toluene, xylene, tetrahydrofuran, chloroform, 1,3-butanediol, 2-butanol, linalool, geraniol, d-limonene, p-cymene, terpinene, phellandrene, terpineol, menthol, eucalyptol, cinnamaldheyde, nitrobenzene, N,N-dimethylformamide and water has been determined. Experimental results have shown that to develop a 'green process' the constituents of essential oils, d-limonene, p-cymene, terpinene, phellandrene, are the most appropriate solvents. The action of these solvent does not produce any degradation of polymer chains. The solubility of the polymer in the mentioned solvents at different temperatures has been investigated. The solvent can be easily recycled by distillation.

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

Science.gov (United States)

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

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

Catalytic hydrotreating of lignin with water-soluble molybdenum catalyst

Energy Technology Data Exchange (ETDEWEB)

Osmaa, A.; Johansson, A. (Technical Research Centre of Finland, Espoo (Finland). Lab. of Fuel and Process Technology)

High yields (61% of the original lignin) of low molecular weight oil (84% of the oil eluted through GC) have been obtained by hydrotreating kraft pine lignin with a water-soluble molybdenum catalyst at 430[degree]C for 60 min. The main compounds in the product oil were phenols (8.7% of the original lignin), cyclohexanes (5.0%), benzenes (3.8%), naphthalenes (4.0%), and phenanthrenes (1.2%). The degree of hydrodeoxygenation was 98%. The quality (measured by GPC and GC) of the product was as good as when using more expensive solid NiMo-CR[sub 2]O[sub 3] catalysts. 30 refs., 6 tabs.

Variability of benzene exposure among filling station attendants

International Nuclear Information System (INIS)

Carere, A.; Iacovella, N.; Turrio Baldassarri, L.; Fuselli, S.; Iavarone, I.; Lagorio, S.; Proietto, A.R.

1996-12-01

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

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

Science.gov (United States)

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

2015-01-01

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

Vertically averaged approaches for CO 2 migration with solubility trapping

KAUST Repository

Gasda, S. E.; Nordbotten, J. M.; Celia, M. A.

2011-01-01

The long-term storage security of injected carbon dioxide (CO2) is an essential component of geological carbon sequestration operations. In the postinjection phase, the mobile CO2 plume migrates in large part because of buoyancy forces, following

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

NARCIS (Netherlands)

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

2007-01-01

A 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

Benzene in blood as a biomarker of low level occupational exposure

Energy Technology Data Exchange (ETDEWEB)

Brugnone, F.; Perbellini, L.; Romeo, L.; Cerpelloni, M.; Bianchin, M.; Tonello, A. [Institute of Occupational Medicine, University of Verona, Policlinico Borgo Roma, 37134 Verona (Italy)

1999-09-01

The occupational airborne exposure to benzene of 150 workers employed in petrol stations and a refinery plant was assessed using personal sampling pumps. All workers provided blood samples after the end of work and on the following morning before resuming work. Benzene concentrations in the blood of 243 non-occupationally-exposed subjects were also measured. The median occupational benzene exposure for all 150 workers studied was 80 {mu}g/m{sup 3}. Overall median blood benzene of all workers was 251 ng/l at the end of the shift, and 174 ng/l the following morning. The benzene concentrations measured in blood collected the following morning proved to be significantly lower than those measured at the end of the shift. Median blood benzene for the 243 'normal' subjects was 128 ng/l, which was significantly lower than that measured in the workers before a new work shift. The median blood benzene concentration was significantly higher in smokers than in non-smokers, both in the general population (210 ng/l vs. 110 ng/l) and in the exposed workers at the end of the shift (476 ng/l vs. 132 ng/l) and the following morning (360 ng/l vs. 99 ng/l). End-of-shift blood benzene correlated significantly with environmental exposure; this correlation was better in the 83 non-smokers than in the 67 smokers. In non-smokers with the median benzene occupational exposure of 50 {mu}g/m{sup 3}, no difference was found in blood benzene concentration in exposed and non-exposed subjects.

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

International Nuclear Information System (INIS)

Almeida, Kelly Cristina Santana de

2006-01-01

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

40 CFR 80.1275 - How are early benzene credits generated?

Science.gov (United States)

2010-07-01

...), per § 80.1280(a). Bavg,y = Average benzene concentration of gasoline produced at the refinery during averaging period y (volume percent benzene), per § 80.1238. Ve,y = Total volume of gasoline produced at the... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading...

Evidence that humans metabolize benzene via two pathways.

NARCIS (Netherlands)

Rappaport, S.M.; Kim, S.; Lan, Q.; Vermeulen, R.C.H.; Waidyanatha, S.; Zhang, L.; Li, G.; Yin, S.; Hayes, R.B.; Rothman, N.; Smith, M.T.

2009-01-01

BACKGROUND: Recent evidence has shown that humans metabolize benzene more efficiently at environmental air concentrations than at concentrations > 1 ppm. This led us to speculate that an unidentified metabolic pathway was mainly responsible for benzene metabolism at ambient levels. OBJECTIVE: We

Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

International Nuclear Information System (INIS)

Mansoori, Y.; Darvishi, K.

2014-01-01

New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T g . In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

Energy Technology Data Exchange (ETDEWEB)

Mansoori, Y.; Darvishi, K., E-mail: ya_mansoori@yahoo.com [University of Mohaghegh Ardabili, Faculty of Science, Department of Applied Chemistry, Daneshgah, Ardabil (Iran, Islamic Republic of)

2014-10-01

New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T{sub g}. In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

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

Energy Technology Data Exchange (ETDEWEB)

Abu Laban, Nidal [Helmholtz (Germany)

2011-07-01

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.

Progress of epidemiological and molecular epidemiological studies on benzene in China.

Science.gov (United States)

Li, Guilan; Yin, Songnian

2006-09-01

Benzene is an organic solvent that has been used in industry for about 100 years throughout the world. Since 1973, a series of toxicological and molecular epidemiological studies on benzene were conducted by researchers at the Chinese Academy of Preventive Medicine (CAPM) (1973-1986) and subsequently by a collaboration between the CAPM and the National Cancer Institute (NCI) in the United States that began in 1986, which was joined by investigators from the University of California at Berkeley, the University of North Carolina at Chapel Hill, and New York University. The findings demonstrated that the risk of leukemia and lymphoma among benzene-exposed workers was significantly increased, with elevated risks for leukemia present not only at higher exposure but also among workers exposed to under 10 ppm. Therefore, the benzene permissible level was decreased to 1.8 ppm (6 mg/m(3)) and benzene-induced leukemia is treated as an occupational cancer in China. The benzene permissible level is 1.0 in the United States and in several other developed countries and it has been suggested to be decreased to 0.5 ppm (ACGIH). A number of potential biomarkers are related to benzene exposure and poisoning. Some of these are benzene oxide-protein adducts, chromosome aberration of lymphocytes, and GPA mutations in erythrocytes, a decrease in B cell and CD4(-)T cell counts in peripheral blood, and altered expression of CXCL16, ZNF331, JUN, and PF4 in lymphocytes. Variation in multiple benzene metabolizing genes may be associated with risk of benzene hematotoxicity, including CYP2E1, MPO, NQO1, and GSTT1.

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: mhfulekar@yahoo.com [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)

2010-03-15

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.

Dehydrogenation of benzene on Pt(111) surface

Science.gov (United States)

Gao, W.; Zheng, W. T.; Jiang, Q.

2008-10-01

The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

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

Science.gov (United States)

Nicholson, Carla A; Fathepure, Babu Z

2004-02-01

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

Study of benzene release from Savannah River in-tank precipitation process slurry simulant

International Nuclear Information System (INIS)

Rappe, K.G.; Gauglitz, P.A.

1998-08-01

At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry simulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every minute

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

Science.gov (United States)

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

2017-05-15

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

Catalytic conversion of alcohols to hydrocarbons with low benzene content

Energy Technology Data Exchange (ETDEWEB)

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

2016-03-08

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.

Catalytic conversion of alcohols to hydrocarbons with low benzene content

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-06

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.

Mechanism of microsomal metabolism of benzene to phenol

Energy Technology Data Exchange (ETDEWEB)

Hinson, J.A.; Freeman, J.P.; Potter, D.W.; Mitchum, R.K.; Evans, F.E.

1985-05-01

The mechanism of microsomal hydroxylation of benzene to phenol has been studied by examining the microsomal metabolism of the specifically deuterated derivative 1,3,5-(/sub 2/H/sup 3/)benzene. Evidence for the formation of the following four products was obtained: 2,3,5-(/sub 2/H/sup 3/)phenol, 3,5-(/sub 2/H/sup 2/)phenol, 2,4,6-(/sub 2/H/sup 3/)phenol, and 2,4-(/sub 2/H/sup 2/)phenol. The presence of 2,3,5-(2H3)phenol and 2,4-(/sub 2/H/sup 2/)phenol shows that, in the microsomal metabolism of benzene to phenol, a NIH shift had occurred. A deuterium isotope effect (kH/kD) of approximately 4 was detected in both the meta- and para-deuterated phenols. This finding indicates that cyclohexadienone, formed either by isomerization of the epoxide or directly from the enzyme-substrate complex, is a major intermediate in the metabolism of benzene to phenol.

(Liquid + liquid) equilibria for benzene + cyclohexane + N,N-dimethylformamide + sodium thiocyanate

International Nuclear Information System (INIS)

Dong, Hongxing; Yang, Xiaoguang; Yue, Guojun; Zhang, Wei; Zhang, Jin

2013-01-01

Graphical abstract: On the left, the figure was phase diagram about the LLE date. On the right, the figure was about the effects of mass fraction of benzene in the raffinate phase to the selectivity(S) coefficient under different salt concentration. ■, the NaSCN and DMF in ratio of 5/95; • , the NaSCN and DMF in ratio of 10/90; ▴, the NaSCN and DMF in ratio of 15/85; ★, the NaSCN and DMF in ratio of 20/80; ▾, the NaSCN and DMF in ratio of 23/77. ♦, only DMF was used extractant (the selectivity coefficient was calculated by literature 17). w 22 , refer to the mass fraction of benzene in the raffinate phase (cyclohexane-rich phase). Highlights: • (Liquid + liquid) equilibrium for quaternary system was measured. • The components include benzene, cyclohexane, N,N-dimethylformamide, sodium thiocyanate. • The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. • Separation of benzene and cyclohexane by NaSCN + DMF was discussed. -- Abstract: (Liquid + liquid) equilibrium (LLE) data for benzene + cyclohexane + N,N-dimethylformamide (DMF) + sodium thiocyanate (NaSCN) were measured experimentally at atmospheric pressure and 303.15 K. The selectivity coefficients from these LLE data were calculated and compared to those previously reported in the literature for the systems (benzene + cyclohexane + DMF) and (benzene + cyclohexane + DMF + KSCN). The NRTL equation was used to correlate the experimental data. The agreement between the predicted and experimental results was good. It was found that the selectivity coefficients of DMF + NaSCN for benzene ranged from 2.45 to 11.99. Considering the relatively high extraction capacity and selectivity for benzene, DMF + NaSCN may be used as a potential extracting solvent for the separation of benzene from cyclohexane

Processing behaviors of thin-film pentacene and benzene-1,4-diboronic acid in supercritical carbon dioxide

International Nuclear Information System (INIS)

Ngo, Truc T.; Keegan, James E.; George, Robert D.

2011-01-01

This research investigates the feasibility of using supercritical carbon dioxide (scCO 2 ) as a green solvent for processing organic thin film semiconductor, such as pentacene, and a potential molecular modifier for use in electronic device applications. Benzene-1,4-diboronic acid (BDBA) was selected as a molecular modifier in this work due to its electron deficient nature, which can potentially enhance pentacene's physical, chemical or electronic properties by changing its structure in the solid state. In this study, the solubilities of BDBA and pentacene in scCO 2 are measured as individual compounds and as co-solutes, at 313 K, using ultraviolet (UV) spectroscopy. Methanol co-solvent effects on solubility have also been characterized for each compound. The results show that BDBA is insoluble in pure scCO 2 up to 1.82 × 10 7 Pa. However, with a small amount of methanol added to the mixture, BDBA becomes soluble in solution with a solubility of 3.81 × 10 −4 mol/l at 9.00 × 10 6 -Pa-pressure. In contrast, pentacene is only soluble in scCO 2 at pressures above 1.10 × 10 7 Pa, and its solubility is decreased upon addition of methanol due to the non-polar nature of pentacene. When a pentacene thin film is treated with BDBA in scCO 2 /methanol solution, BDBA sorption is observed at pressures as low as 8.80 × 10 6 Pa. Based on these results, it is concluded that treatment of pentacene thin films in scCO 2 is a promising approach that can be optimized for BDBA and other similar molecular modifiers, to produce multi-component organic thin film devices.

An analysis of violations of Osha's (1987) occupational exposure to benzene standard.

Science.gov (United States)

Williams, Pamela R D

2014-01-01

The Occupational Safety and Health Administration (OSHA), which was formed by the Occupational Safety and Health Act of 1970 (OSH Act), establishes enforceable health and safety standards in the workplace and issues violations and penalties for non-compliance with these standards. The purpose of the current study was to evaluate the number and type of violations of the OSHA (1987) Occupational Exposure to Benzene Standard. Violations of the OSHA Hazard Communication Standard (HCS), particularly those that may pertain to specific provisions of the benzene standard, were also assessed. All analyses were based on OSHA inspection data that have been collected since the early 1970s and that are publicly available from the U.S. Department of Labor enforcement website. Analysis of these data shows that fewer than a thousand OSHA violations of the benzene standard have been issued over the last 25+ years. The results for benzene are in contrast to those for some other toxic and hazardous substances that are regulated by OSHA, such as blood-borne pathogens, lead, and asbestos, for which there have been issued tens of thousands of OSHA violations. The number of benzene standard violations also varies by time period, standard provision, industry sector, and other factors. In particular, the greatest number of benzene standard violations occurred during the late 1980s to early/mid 1990s, soon after the 1987 final benzene rule was promulgated. The majority of benzene standard violations also pertain to noncompliance with specific provisions and subprovisions of the standard dealing with initial exposure monitoring requirements, the communication of hazards to employees, and medical surveillance programs. Only a small fraction of HCS violations are attributed, at least in part, to potential benzene hazards in the workplace. In addition, most benzene standard violations are associated with specific industries within the manufacturing sector where benzene or benzene

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

Science.gov (United States)

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

2014-06-30

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

Benzene adsorption and hydrogenation on Pd-Ru alloy by pulse chromatography

International Nuclear Information System (INIS)

Dobrokhotov, V.G.; Pavlova, L.F.; Gryaznov, V.M.

1983-01-01

Pulse chromatography has been applied to investigate benzene adsorption and hydrogenation on the Walls of a capillary of the Pd-6% Ru alloy at different hydrogen contents in the alloy and various methods of hydrogen supply: as a mixture with benzene vapors or by diffusion through the walls of the capillary. It is stated that reversible adsorption of benzene vapors on the Pd-6% Ru alloy at 303 K under the conditions of the β-phase existence in the alloy-hydrogen system does not change whereas in the region of the α-phase existence it slightly increases with a growth of hydrogen pressure. Strongly adsorbed benzene occupies approximately 7% of the surface. Only strongly adsorbed benzene is hydrogenated on the α-phase of the alloy-hydrogen system. Hydrogen supply to the hydrogenation zone by diffusion throUgh the alloy results in supersaturation of the surface active in the reaction of benzene hydrogenation with a chemisorbed hydrogen form

Peer Review Comments on the IRIS Assessment of Benzene

Science.gov (United States)

Attachment to IRIS file for benzene, January 19, 2000, RESPONSE TO THE PEER REVIEW COMMENTS, II. Extrapolation of the Benzene Inhalation Unit Risk Estimate to the Oral Route of Exposure (EPA/NCEA-W-0517, July 1999)

Destruction of benzene (VOC) using electron beam radiation in flue gas treatment

International Nuclear Information System (INIS)

Mohd Nahar Othman; Mohd Noor Muhd Yunus

2004-01-01

In this study, Benzene, one of the volatile organic compounds (VOCs) is used to destruct by electron beam. As we know Benzene is one of the most stable compound and very difficult to break. By using the powerful energy produced by electron beam, the benzene compound can be broken up to form new compounds. The technique used in this experiment is by using static process in a control condition where other gases are not allowed to enter the Tedlar bag or glass jar. The Tedlar Bag and Glass jar are used as media for benzene gas to be irradiated. From the experiment it was found that the Tedlag Bag is more suitable than the glass jar the electron beam can easily penetrate and destroy benzene gas. Nitrogen and Helium gas is used as a cleaning gas. The concentrations of benzene gas used for this study are 100 ppm. (part per million), 1 ppmv, and 1 ppmv each for 32 types of VOC. From the result it can be concluded that the electron beam technique used for destruction of benzene (VOQ is very suitable for the low concentration of benzene, the dose needed for the destruction to reach 85-95% is only between 8-12 kGy. It was also observed that many new compound can be produced when benzene is destruct by electron beam. (Author)

STABILITY OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE AND 1,4-BENZOQUINONE AFTER ADMINISTRATION OF BENZENE TO F344 RATS

Science.gov (United States)

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 ...

Establishment of a Methanogenic Benzene-Degrading Culture and its Implication in Bioremediation

Science.gov (United States)

Qiao, W.; Luo, F.; Bawa, N.; Guo, S.; Ye, S.; Edwards, E.

2017-12-01

Benzene is a known human carcinogen and it is a common pollutant in groundwater, mainly resulting from petrochemical industry. Anaerobic degradation of benzene has significant advantages over aerobic processes for in situ bioremediation. In this study, new methanogenic and sulfate-reducing benzene degrading cultures have been enriched. Microbial community composition was characterized with two other previously established benzene-degrading cultures, and their potential use in bioaugmentation is investigated. In this study, a lab microcosm study was conducted anaerobically with contaminated soil and groundwater from a former chemical plant. Benzene degradation was observed in the presence of co-contaminants and electron donor. Through repetitive amendment of benzene, two enrichment cultures have been developed under sulfate and methanogenic conditions. Results from DNA amplicon sequencing and qPCR analysis revealed that an organism similar to previously described benzene-degrading Deltaproteobacterium has been enriched. The microbial community of this culture was compared with other two methanogenic benzene-degrading enrichment cultures that were derived from an oil refinery and a decommissioned gasoline station, and have been maintained for decades. Deltaproteobacterium ORM2-like microbes were dominate in all enrichment cultures, which brought to light benzene-degrading microbes, ORM2 were enriched under different geological conditions distributed around the world. The relative abundance of methanogens was much lower compared to previously established cultures, although substantial amount of methane was produced. The peripheral organisms also vary. To investigate effectiveness of using ORM2-dominant enrichment cultures in bioremediation, microcosm studies were set up using contaminated materials, and a ORM2-dominating methanogenic benzene-degrading culture was used for bioaugmentation. Results revealed that benzene degradation was speeded up under methanogenic or

Cultivating microbial dark matter in benzene-degrading methanogenic consortia.

Science.gov (United States)

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

2016-09-01

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). © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

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

International Nuclear Information System (INIS)

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

2004-12-01

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.)

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

Science.gov (United States)

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

2015-11-01

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.

[Myelofibrosis in a benzene-exposed cleaning worker].

Science.gov (United States)

Bausà, Roser; Navarro, Lydia; Cortès-Franch, Imma

Long-term exposure to benzene has been associated with several blood malignancies, including aplastic anemia, myeloproliferative neoplasms, and different leukemias. We present a case of primary myelofibrosis in a 59-year-old woman who worked as a cleaner at a car dealership and automobile mechanic shop. For 25 years, she used gasoline as a degreaser and solvent to clean engine parts, floors and work desks on a daily basis. She was referred by her primary care provider to the Occupational Health Unit of Barcelona to assess whether her illness was work-related. Review of her job history and working conditions revealed chronic exposure to benzene in the absence of adequate preventive measures. An association between benzene exposure and myeloproliferative disease was established, suspicious for an occupational disease. Copyright belongs to the Societat Catalana de Salut Laboral.

Polyfunctional catalyst for processiing benzene fractions

Energy Technology Data Exchange (ETDEWEB)

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

2009-05-15

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

Interim report: Study of benzene release from Savannah River in-tank precipitation process slurry simulant

International Nuclear Information System (INIS)

Rappe, K.G.; Gauglitz, P.A.

1997-09-01

At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form a 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses both flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry stimulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every 3 minutes. The following 75-mL samples were measured for release rates: KTPB slurry with 15,000 ppm freshly added benzene that was gently mixed with the slurry, KTPB slurry homogenized (energetically mixed) with 15,000 ppm and 5,000 ppm benzene, clear and filtered KTPB salt solution saturated with benzene (with and without a pure benzene layer on top of the solution), and a slurry sample from a large demonstration experiment (DEMO slurry) containing-benzene generated in situ

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.

2011-10-15

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)

Radiolysis of triphenylarsine in a mixture of benzene and cyclohexane. [. gamma. radiation

Energy Technology Data Exchange (ETDEWEB)

Nazir, S B; Rai, R S [Birla Inst. of Tech. and Science, Pilani (India). Dept. of Chemistry

1975-06-01

A number of degassed samples of triphenylarsine were irradiated by gamma radiation in a mixture of benzene and cyclohexane. The condensable products formed were pentane, hexane, benzene and cyclohexane in cyclohexane solution containing triphenylarsine and cyclohexane in benzene in presence of triphenylarsine. When the composition of the solvent was varried by stepwise addition of benzene from 5 to 50%, the main condensable radiolytic products observed by vapour phase chromatography were hexane, : hexane and cyclohexene. No pentane was observed when benzene was present in the mixture upto 15%. However, it was detected in the presence of 20-30% benzene mixture. When the amount of benzene was 35-50% in the mixture, two isomers of hexane and hexene were also detected. A mechanism has been worked out for the formation of these compounds and protection and sensitization mechanisms have been invoked to explain the yields per 100 ev. From the kinetic analysis, it has been found out that the rate of formation of cyclohexene is much faster than rates of different products formed during gamma radiolysis and from the analysis of experimental data, sponge type protection has been postulated in this radiolytic system.

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

Energy Technology Data Exchange (ETDEWEB)

Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [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)

2011-11-15

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.

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

International Nuclear Information System (INIS)

Cervantes, Francisco J.; Mancilla, Ana Rosa; Toro, E. Emilia Rios-del; Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia

2011-01-01

Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-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 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L -1 , linked to the reduction of 619 ± 81 μEq L -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 γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

Canada-wide standard for benzene phase 1 : Progress report 2001

International Nuclear Information System (INIS)

2001-01-01

In June 2000, the Canadian Council of Ministers of the Environment (CCME) ratified the Canada-Wide Standard (CWS) for Benzene Phase 1. Benzene is classified as a carcinogen to humans and any level of exposure is generally considered to carry some probability of harmful effects. The Ministers committed to reducing national benzene emissions by 30 per cent between 1995 and 2000. This report presents the progress thus far and describes how the Alberta Government has focused on effecting emission reductions in the natural gas sector, dehydrators, petroleum refineries and in chemical manufacturing plants. Their initiatives led to a 66 per cent decrease in benzene emissions by 1999. In addition, overall emissions in the province were reduced by 50 per cent from industry and mobile sources. The measures initiated during Phase 1 will continue beyond the time frame, and Phase 2, not yet ratified, will call for a follow-through on those measures. Phase 2 recognizes best management practices and jurisdictional regulations that will minimize emissions. Specifically, Phase 2 calls for an additional reduction of 6 kilotonnes in benzene emissions for existing facilities by the end of 2010. The minimization of benzene emissions through the application of best available pollution prevention and control techniques is contained for new and expanding facilities. The implementation of the CWS comprises the follow-up of existing initiatives resulting from the application of Phase 1 and the promotion and application of best management practices for new and expanding facilities, the determination and tracking of ancillary emission reductions of benzene realized as a result of other CWS initiatives, and the monitoring and reporting of progress. 13 refs., 4 tabs., 3 figs

Dynamics of Rb{sup +}-benzene and Rb{sup +}-benzene-Ar {sub n} (n {<=} 3) clusters

Energy Technology Data Exchange (ETDEWEB)

Alberti, M. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain)], E-mail: m.alberti@ub.edu; Aguilar, A. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Lucas, J.M. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Cappelletti, D. [Dipartimento di Ingegneria Civile ed Ambientale, Universita di Perugia, 06123 Perugia (Italy); Lagana, A. [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy); Pirani, F. [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy)

2006-09-29

The potential energy function of the Rb{sup +}-benzene cluster and of some of its Ar solvated variants is here modeled using a combination (pairwise sum) of ion(atom)-molecular bond and ion-molecular charges interaction contributions which provide, respectively, the non electrostatic and the electrostatic terms of the total non covalent intermolecular potential energy. In particular, such interaction contributions have been represented using, in addition to the ion(atom) polarizability, the bond polarizability tensor components and the charge distribution which account, respectively, for the polarizability and the quadrupolar moment of the benzene molecule. On the resulting potential energy surface, dynamical calculations have been carried out for the microcanonical ensemble by focusing on isomerization processes and on the effect of the mass of the cation.

Pressure Dependence of Molar Volume near the Melting Point in Benzene

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

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.

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

International Nuclear Information System (INIS)

Dougal, R.A.

1993-08-01

High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a 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 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 μg/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. 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

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

2014-01-01

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...

Formation of a new benzene-ethane co-crystalline structure under cryogenic conditions.

Science.gov (United States)

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

2014-06-12

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.

Repository-analog experiments of nuclear waste leaching and migration

International Nuclear Information System (INIS)

Seitz, M.G.

1982-01-01

The potential for radionuclide migration from a breached nuclear-waste repository depends on the leaching and subsequent interaction of the leached radionuclides with materials in the groundwater flow path. An attempt is made to consider all interactions using experiments that integrate repository materials. Results of a repository-analog experiment using borosilicate glass, fissured granite, and flowing water suggest: (1) plutonium was immobile possibly because of its low solubility; (2) caesium migrated down slowly because of sorption; and (3) neptunium remained oxidized even in water of low oxidation potential. By summing the effects of all interactions, not just sorption, the repository-analog experiment produced radionuclide migration that could be expected from a breached repository. (author)

Photocatalytic Hydrogen-Evolution Cross-Couplings: Benzene C-H Amination and Hydroxylation.

Science.gov (United States)

Zheng, Yi-Wen; Chen, Bin; Ye, Pan; Feng, Ke; Wang, Wenguang; Meng, Qing-Yuan; Wu, Li-Zhu; Tung, Chen-Ho

2016-08-17

We present a blueprint for aromatic C-H functionalization via a combination of photocatalysis and cobalt catalysis and describe the utility of this strategy for benzene amination and hydroxylation. Without any sacrificial oxidant, we could use the dual catalyst system to produce aniline directly from benzene and ammonia, and phenol from benzene and water, both with evolution of hydrogen gas under unusually mild conditions in excellent yields and selectivities.

Disturbance response indicators of Impatiens walleriana exposed to benzene and chromium.

Science.gov (United States)

Campos, V; Lessa, S S; Ramos, R L; Shinzato, M C; Medeiros, T A M

2017-08-03

The purpose of this study was to evaluate the remediation potential and disturbance response indicators of Impatiens walleriana exposed to benzene and chromium. Numerous studies over the years have found abundant evidence of the carcinogenicity of benzene and chromium (VI) in humans. Benzene and chromium are two toxic industrial chemicals commonly found together at contaminated sites, and one of the most common management strategies employed in the recovery of sites contaminated by petroleum products and trace metals is in situ remediation. Given that increasing interest has focused on the use of plants as depollution agents, direct injection tests and benzene misting were performed on I. walleriana to evaluate the remediation potential of this species. I. walleriana accumulated hexavalent chromium, mainly in the root system (164.23 mg kg -1 ), to the detriment of the aerial part (39.72 mg kg -1 ), and presented visible damage only at the highest concentration (30 mg L -1 ). Unlike chromium (VI), chromium (III) was retained almost entirely by the soil, leaving it available for removal by phytotechnology. However, after the contamination stopped, I. walleriana responded positively to the detoxification process, recovering its stem stiffness and leaf color. I. walleriana showed visible changes such as leaf chlorosis during the ten days of benzene contamination. When benzene is absorbed by the roots, it is translocated to and accumulated in the plant's aerial part. This mechanism the plant uses ensures its tolerance to the organic compound, enabling the species to survive and reproduce after treatment with benzene. Although I. walleriana accumulates minor amounts of hexavalent chromium in the aerial part, this amount suffices to induce greater oxidative stress and to increase the amount of hydrogen peroxide when compared to that of benzene. It was therefore concluded that I. walleriana is a species that possesses desirable characteristics for phytotechnology.

Human risk assessment of benzene after a gasoline station fuel leak

Directory of Open Access Journals (Sweden)

Miriam dos Anjos Santos

2013-06-01

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.

Measurement and correlation of the solubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in different solvents

International Nuclear Information System (INIS)

Lan, Guan-Chao; Wang, Jian-Long; Chen, Li-Zhen; Hou, Huan; Li, Jing; Gao, Yu-Peng

2015-01-01

Highlights: • The laser monitoring system was used for measuring the solubilities of DNTF. • Three correlation equations were adopted to correlate the experimental values. • The three-dimensional figure between ln x i and 1/T, ln T was obtained. • Thermodynamic properties were calculated by the experimental solubilities. - Abstract: A knowledge of the solubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in different solvents is essential for crystallization and further theoretical studies. The laser monitoring system was used for measuring the solubility of DNTF in methanol, ethanol, acetic acid, benzene, toluene and n-butanol at temperatures ranging from (298.15 to 338.15) K. Polynomial empirical equation, ideal model and modified Apelblat equation were used to correlate the experimental values. The correlated results of three correlation equations present good consistency with the experimental values. In addition, the modified Apelblat equation produced higher accuracy than the polynomial empirical equation and the ideal equation. The standard dissolution enthalpy, standard dissolution entropy and the Gibbs energy were calculated from the experimental values. The solubility values of DNTF and correlation equations from this experiment would be invoked as basic data and models regarding the crystallization process of DNTF

The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory

Energy Technology Data Exchange (ETDEWEB)

Ottonello, Giulio, E-mail: giotto@dipteris.unige.it [DISTAV, Università di Genova, Corso Europa 26, 16132 Genova (Italy); Richet, Pascal [Institut de Physique du Globe, Rue Jussieu 2, 75005 Paris (France)

2014-01-28

The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ε) of the investigated silicate melts and its optical counterpart (ε{sup ∞}) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter σ{sub s}, along the guidelines already used in the past for simple media such as water or benzene. The σ{sub s} obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25 °C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great

The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory.

Science.gov (United States)

Ottonello, Giulio; Richet, Pascal

2014-01-28

The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ɛ) of the investigated silicate melts and its optical counterpart (ɛ(∞)) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter σs, along the guidelines already used in the past for simple media such as water or benzene. The σs obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25 °C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of

The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory

International Nuclear Information System (INIS)

Ottonello, Giulio; Richet, Pascal

2014-01-01

The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ε) of the investigated silicate melts and its optical counterpart (ε ∞ ) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter σ s , along the guidelines already used in the past for simple media such as water or benzene. The σ s obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25 °C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of

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

Science.gov (United States)

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

2016-05-01

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

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian; Mi, Wenbo; Wang, Xiaocha; Wang, Xuhui

2015-01-01

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.

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian

2015-05-27

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.

Benzene and its Isomers

Indian Academy of Sciences (India)

organic chemistry in particular is the period between 1825 when benzene was isolated and 1865 when its correct structure was proposed. Significant initial strides were made during these years in finding new organic reactions and searching for meth- ods to draw molecular structures. For an average chemist the molecular ...

Geogenic sources of benzene in aquifers used for public supply, California

Science.gov (United States)

Landon, Matthew K.; Belitz, Kenneth

2012-01-01

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.

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)

2014-04-15

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

Assessment of Benzene Exposures in the Working Environment at Gasoline Stations

Directory of Open Access Journals (Sweden)

Sunisa Chaiklieng

2015-07-01

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.

Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling

International Nuclear Information System (INIS)

Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

2014-01-01

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 (V o,d ) initially increase and then decrease. The V o,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 V o,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. -- Highlights: • The microporosity estimated by benzene vapor differs greatly from that by N 2 . • The micropore volume changes with kerogen maturation. • The phenanthrene or benzene sorption is related to the microporosity of kerogen. • Higher adsorption volume for benzene than for phenanthrene suggests molecular sieve effect. • The pore-filling plays an important role in the sorption of phenanthrene and benzene. -- The sorption behaviors of benzene and phenanthrene are related to the microporosity of the differently matured kerogen, indicating the importance of pore-filling

Gradient biomaterials and their influences on cell migration

Science.gov (United States)

Wu, Jindan; Mao, Zhengwei; Tan, Huaping; Han, Lulu; Ren, Tanchen; Gao, Changyou

2012-01-01

Cell migration participates in a variety of physiological and pathological processes such as embryonic development, cancer metastasis, blood vessel formation and remoulding, tissue regeneration, immune surveillance and inflammation. The cells specifically migrate to destiny sites induced by the gradually varying concentration (gradient) of soluble signal factors and the ligands bound with the extracellular matrix in the body during a wound healing process. Therefore, regulation of the cell migration behaviours is of paramount importance in regenerative medicine. One important way is to create a microenvironment that mimics the in vivo cellular and tissue complexity by incorporating physical, chemical and biological signal gradients into engineered biomaterials. In this review, the gradients existing in vivo and their influences on cell migration are briefly described. Recent developments in the fabrication of gradient biomaterials for controlling cellular behaviours, especially the cell migration, are summarized, highlighting the importance of the intrinsic driving mechanism for tissue regeneration and the design principle of complicated and advanced tissue regenerative materials. The potential uses of the gradient biomaterials in regenerative medicine are introduced. The current and future trends in gradient biomaterials and programmed cell migration in terms of the long-term goals of tissue regeneration are prospected. PMID:23741610

Benzene degradation coupled with chlorate reduction in soil column study

NARCIS (Netherlands)

Tan, N.C.G.; Doesburg, van W.C.J.; Langenhoff, A.A.M.; Stams, A.J.M.

2006-01-01

Perchlorate and chlorate are electron acceptors that during reduction result in the formation of molecular oxygen. The produced oxygen can be used for activation of anaerobic persistent pollutants, like benzene. In this study chlorate was tested as potential electron acceptor to stimulate benzene

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

Science.gov (United States)

Halliday, Hannah Selene

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

Story of skeletally substituted benzenes

Indian Academy of Sciences (India)

Unknown

values are extensively used to define aromaticity quantitatively.3 In a recent study on ... studies were directed to unravel the subtle ways in which the stability, reactivity, and ..... The singlet–triplet gaps of all the skeletally substituted benzenes ...

Evaluation of radionuclide migration in the homogeneous system of a geological repository

International Nuclear Information System (INIS)

Prvakova, S.; Duran, J.; Necas, V.

2005-01-01

The aim of this paper is to study radionuclide migration and release from a deep underground repository situated in a clay formation. An insight into the processes influencing the radionuclide transport in the near field and far field will be presented. For the calculation, a set of radionuclides has been chosen, considering the half-life, decay chains, capacity of the sorption, solubility limits and diffusion coefficients. The migration of radionuclides is dependent on transport properties of the particular nuclide. Due to the low hydraulic conductivity of the backfill material and clay geological formation, the transport in the repository occurs mainly by diffusion. The migration rate will be influenced by the water chemistry, solubility, retardation and diffusive properties of the nuclides, and the water flow rate in the clay. The release rates of radionuclides from the geosphere to the biosphere will be converted into the indicative dose rates using dose conversion factors for ingestion. The impact of the critical group is considered via consumption of meat, root vegetables and drinking water from wells. (author)

High-efficiency plasma catalytic removal of dilute benzene from air

International Nuclear Information System (INIS)

Fan, Hong-Yu; Shi, Chuan; Li, Xiao-Song; Zhao, De-Zhi; Xu, Yong; Zhu, Ai-Min

2009-01-01

Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min -1 flow rate, the energy cost was as low as 3.7 x 10 -3 kWh m -3 air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

Benzene - exposure and risk evaluation; Benzol - Exposition und Risikoabschaetzung

Energy Technology Data Exchange (ETDEWEB)

Eikmann, T. [Giessen Univ. (Germany). Hygiene-Institut und Umweltmedizin; Eikmann, S. [Gesellschaft fuer Umwelttoxikologie und Krankenhaushygiene mbH, Wetzlar (Germany); Goeen, T. [Technische Hochschule Aachen (Germany). Inst. fuer Hygiene und Arbeitsmedizin

2000-07-01

Benzene is one of the most important environmental carcinogens. Because of its potential to induce leukemia, benzene is noted as carcinogeneous hazardous substance in legal guidelines for occupational use and environmental contact. Epidemiological studies resulted to unit-risk values between 2.8 x 10{sup -6} to 30 x 10{sup -6} for lifelong exposure to 1 {mu}g/m{sup 3} benzene. In Germany, the average unit-risk was estimated to be 9 x 10{sup -6}. The general population is mainly exposed to benzene due to the emissions of motor vehicles. The average annual air concentration of benzene at main roads and in industrial areas are 5 to 30 {mu}g/m{sup 3}. Due to seasonal influences and special exposure situations distinctly higher peak concentrations are occurring. Regional differences, i.e. between rural and urban immission levels and between the concentration in air of the northern and southern part of Europe, are also recognizable. The life-style factor smoking increases the individual exposure distinctly, whereas contamination of the diet contribute little to the total uptake of benzene. The internal exposure of the general population varies due to living area, smoking habits and mobility. Individuals living in no-smoking buildings show benzene concentrations in blood of 15 to 170 ng/l, whereas the benzene level of persons with additional exposures (smoking, frequently use of motor vehicles, etc.) can reach approximately 1000 ng/l blood. Comparable conclusions result from data for the urinary levels of two sensitive metabolites of benzene: trans-, trans-muconic acid and S-phenylmercapturic acid. (orig.) [German] Benzol stellt aufgrund seines ubiquitaeren Auftretens und seiner Leukaemie verursachenden Wirkung eines der bedeutendsten Umweltkanzerogene dar. Es ist als krebserzeugender Gefahrstoff (Gefahrstoffverordnung: Gruppe II) und als eindeutig krebserzeugender Arbeitsstoff (Kategorie 1) ausgewiesen. Aus epidemiologischen Studien ergaben sich Unit

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-09-15

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

Model evaluation for the prediction of solubility of active pharmaceutical ingredients (APIs to guide solid–liquid separator design

Directory of Open Access Journals (Sweden)

Kuveneshan Moodley

2018-05-01

Full Text Available The assumptions and models for solubility modelling or prediction in systems using non-polar solvents, or water and complex triterpene and other active pharmaceutical ingredients as solutes aren't well studied. Furthermore, the assumptions concerning heat capacity effects (negligibility, experimental values or approximations are explored, using non-polar solvents (benzene, or water as reference solvents, for systems with solute melting points in the range of 306–528 K and molecular weights in the range of 90–442 g/mol. New empirical estimation methods for the ΔfusCpi of APIs are presented which correlate the solute molecular masses and van der Waals surface areas with ΔfusCpi. Separate empirical parameters were required for oxygenated and non-oxygenated solutes. Subsequently, the predictive capabilities of the various approaches to solubility modelling for complex pharmaceuticals, for which data is limited, are analysed. The solute selection is based on a principal component analysis, considering molecular weights, fusion temperatures, and solubilities in a non-polar solvent, alcohol, and water, where data was available. New NRTL-SAC parameters were determined for selected steroids, by regression. The original UNIFAC, modified UNIFAC (Dortmund, COSMO-RS (OL, and COSMO-SAC activity coefficient predictions are then conducted, based on the availability of group constants and sigma profiles. These are undertaken to assess the predictive capabilities of these models when each assumption concerning heat capacity is employed. The predictive qualities of the models are assessed, based on the mean square deviation and provide guidelines for model selection, and assumptions concerning phase equilibrium, when designing solid–liquid separators for the pharmaceutical industry on process simulation software. The most suitable assumption regarding ΔfusCpi was found to be system specific, with modified UNIFAC (Dortmund performing well in benzene as

Mineral-like clathrate of cadmium cyanide with benzene

International Nuclear Information System (INIS)

Kitazava, T.; Nishimura, A.

1999-01-01

A new mineral-like clathrate of cadmium cyanide with benzene Cd(CN) 2 ·C 6 H 6 is prepared. Data of x-ray diffraction analysis show that benzene molecule is incorporated in cadmium cyanide lattice and a new mineral-like lattice of Cd(CN) 2 belongs to structures of cristobalite type. Clathrate Cd(CN) 2 ·C 6 H 6 crystallizes in trigonal space group R3m, a=8.953(4), c=21929(6) A [ru

Serum Macrophage Migration Inhibitory Factor in the Prediction of Preterm Delivery

DEFF Research Database (Denmark)

Pearce, Brad; Garvin, Sicily; Grove, Jakob

2008-01-01

Objective: Macrophage migration inhibitory factor (MIF) is a soluble mediator that helps govern the interaction between cytokines and stress hormones (e.g. cortisol). We determined if maternal MIF levels predicted subsequent preterm delivery (PTD). Study Design: A nested case-control study...

Oxidative desulfurization of benzene fraction on transition metal oxides

Science.gov (United States)

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Science.gov (United States)

2010-07-01

... benzene). i = Individual batch of gasoline produced at the refinery from January 1, 2004 through December 31, 2005. n = Total number of batches of gasoline produced at the refinery from January 1, 2004... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading...

Palladium catalyzed direct oxidation of benzene with molecular oxygen to phenol

International Nuclear Information System (INIS)

Jintoku, Tetsuro; Takaki, Ken; Fujiwara, Yuzo; Fuchita, Yoshio; Hiraki, Katsuma.

1990-01-01

Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O 2 via direct activation of a C-H aromatic bond by the Pd(OAc) 2 /phenanthroline catalyst system. The evidence for direct oxidation of benzene by O 2 was obtained using 18 O and 2 H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph-Pd σ complex intermediates. (author)

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

International Nuclear Information System (INIS)

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

2010-01-01

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 μg L -1 ).

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)

2010-07-05

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}).

Instrument for benzene and toluene emission measurements of glycol regenerators

International Nuclear Information System (INIS)

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

2013-01-01

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

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

1997-04-01

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.

An overview of published benzene exposure data by industry in China, 1960-2003.

Science.gov (United States)

Liang, You-Xin; Wong, Otto; Armstrong, Thomas; Ye, Xi-Biao; Miao, Li-Zhuang; Zhou, Yi-Mei; Wu, Qiang-En; Qian, Hao-Jun; Fu, Hua

2005-05-30

This article presents an overview of occupational benzene exposures in China based on data published in Chinese medical journals. The data were derived from 384 reports of benzene poisoning or industrial hygiene surveys published in Chinese medical journals between 1960 and 2003. The following information was extracted whenever available: industry, occupation, task, date, benzene levels, sampling location, workplace descriptions and, for case reports, medical diagnosis. Each paper provided one or more sets of benzene data, each set representing a sampling location or job title with one to several measurements including, mainly, breathing zone area concentration measurements, and much less frequently personal monitoring. Two criteria based on data quality were applied to select suitable data for analyses. The selected exposure data were analyzed by industry and time period. Nine hundred five sets of benzene measurements from 72 industries were reported in the 384 papers selected for this review, and 621 sets (68.6%) presented average benzene concentrations, which covered 55 industries. The distribution of the reported average benzene exposures was skewed with a median of 51.5 mg/m3. The average benzene concentrations were below 100 mg/m3 for 406 (65%) of the 621 reported average concentrations. The medians of the reported averages in mg/m3 for the five industries with the highest exposures were: 124.8 for leather products, 98.7 for electronic devices, 75.4 for machinery, 50.4 for shoes, and 50.3 for office supplies and sports equipment manufacturing. These data describe the concentrations and changing patterns of occupational benzene exposure by industry and time period in China.

Benzene exposure in the shoemaking industry in China, a literature survey, 1978-2004.

Science.gov (United States)

Wang, Laiming; Zhou, Yimei; Liang, Youxin; Wong, Otto; Armstrong, Thomas; Schnatter, A Robert; Wu, Qiangen; Fang, Jinbin; Ye, Xibiao; Fu, Hua; Irons, Richard D

2006-11-01

This article presents a summary of benzene exposure levels in the shoemaking industry in China reported in the Chinese medical literature between 1978 and 2004. A comprehensive search identified 182 papers reporting such exposure data. These papers could be classified into two categories: benzene poisoning case reports and industrial hygiene surveys. From each paper, the following information was abstracted whenever available: location and year of occurrence, occupation and/or task involved, benzene content in adhesives/solvents, work environment, working conditions, working hours, diagnosis, and air monitoring data of benzene. A total of 333 benzene measurements (88 averages, 116 minimums, 129 maximums) in the shoemaking industry were reported in the 182 papers identified. The data were analyzed in terms of geographical location, time period, type of ownership (state, township, or foreign), type of report (benzene poisoning reports vs. industrial hygiene surveys), and job title (work activity) or process. The reported data covered a wide range; some measurements were in excess of 4500 mg/m(3). Thirty-five percent of the reported benzene concentrations were below 40 mg/m(3), which was the national occupational exposure limit (OEL) for benzene between 1979 and 2001. The remaining 65% measurements, which exceeded the national OEL in effect at the time, and were distributed as follows: 40-100 mg/m(3), 11%; 100-300 mg/m(3), 21%; 300-500 mg/m(3), 13%; and 500+ mg/m(3), 20%. However, only 24% of the reported measurements after 2002 were below 6 mg/m(3), i.e., Permissible Concentration-Time Weighted Average (PC-TWA) and 10 mg/m(3), i.e., Permissible Concentration-Short Term Exposure Limit (PC-STEL), the newly amended benzene OELs in effect after May 2002. The data demonstrated that the majority of the facilities in the shoemaking industry reported in the literature were not in compliance of the OEL for benzene in effect at the time. Overall, the data show a clear downward

Chemical speciation of radionuclides migrating in groundwaters

International Nuclear Information System (INIS)

Robertson, D.; Schilk, A.; Abel, K.; Lepel, E.; Thomas, C.; Pratt, S.; Cooper, E.; Hartwig, P.; Killey, R.

1994-04-01

In order to more accurately predict the rates and mechanisms of radionuclide migration from low-level waste disposal facilities via groundwater transport, ongoing studies are being conducted at field sites at Chalk River Laboratories to identify and characterize the chemical speciation of mobile, long-lived radionuclides migrating in groundwaters. Large-volume water sampling techniques are being utilized to separate and concentrate radionuclides into particular, cationic, anionic, and nonionic chemical forms. Most radionuclides are migrating as soluble, anionic species that appear to be predominantly organoradionuclide complexes. Laboratory studies utilizing anion exchange chromatography have separated several anionically complexed radionuclides, e.g., 60 Co and 106 Ru, into a number of specific compounds or groups of compounds. Further identification of the anionic organoradionuclide complexes is planned utilizing high resolution mass spectrometry. Large-volume ultra-filtration experiments are characterizing the particulate forms of radionuclides being transported in these groundwaters

Differential migration and proliferation of geometrical ensembles of cell clusters

International Nuclear Information System (INIS)

Kumar, Girish; Chen, Bo; Co, Carlos C.; Ho, Chia-Chi

2011-01-01

Differential cell migration and growth drives the organization of specific tissue forms and plays a critical role in embryonic development, tissue morphogenesis, and tumor invasion. Localized gradients of soluble factors and extracellular matrix have been shown to modulate cell migration and proliferation. Here we show that in addition to these factors, initial tissue geometry can feedback to generate differential proliferation, cell polarity, and migration patterns. We apply layer by layer polyelectrolyte assembly to confine multicellular organization and subsequently release cells to demonstrate the spatial patterns of cell migration and growth. The cell shapes, spreading areas, and cell-cell contacts are influenced strongly by the confining geometry. Cells within geometric ensembles are morphologically polarized. Symmetry breaking was observed for cells on the circular pattern and cells migrate toward the corners and in the direction parallel to the longest dimension of the geometric shapes. This migration pattern is disrupted when actomyosin based tension was inhibited. Cells near the edge or corner of geometric shapes proliferate while cells within do not. Regions of higher rate of cell migration corresponded to regions of concentrated growth. These findings demonstrate that multicellular organization can result in spatial patterns of migration and proliferation.

Water-Soluble Vitamin E-Tocopheryl Phosphate.

Science.gov (United States)

Zingg, Jean-Marc

The hydrophobicity of vitamin E poses transport and metabolic challenges to regulate its bioavailability and to prevent its accumulation in lipid-rich tissues such as adipose tissue, brain, and liver. Water-soluble precursors of vitamin E (α-tocopherol, αT), such as its esters with acetate (αTA), succinate (αTS), or phosphate (αTP), have increased solubility in water and stability against reaction with free radicals, but they are rapidly converted during their uptake into the lipid-soluble vitamin E. Therefore, the bioavailability of these precursors as intact molecules is low; nevertheless, at least for αTS and αTP, the recent research has revealed unique regulatory effects on signal transduction and gene expression and the modulation of cellular events ranging from proliferation, survival/apoptosis, lipid uptake and metabolism, phagocytosis, long term potentiation, cell migration, telomere maintenance, and angiogenesis. Moreover, water-soluble derivatives of vitamin E including some based on αTP are increasingly used as components of nanocarriers for enhanced and targeted delivery of drugs and other molecules (vitamins, including αT and αTP itself, vitamin D3, carnosine, caffeine, docosahexaenoic acid (DHA), insulin) and cofactors such as coenzyme Q10. In this review, the chemical characteristics, transport, metabolic pathways, and molecular mechanisms of action of αTP in cells and tissues are summarized and put into perspective with its possible role in the prevention of a number of diseases. © 2018 Elsevier Inc. All rights reserved.

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Science.gov (United States)

2010-07-01

... baseline? 80.1285 Section 80.1285 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline... credits. (b) For U.S. Postal delivery, the benzene baseline application shall be sent to: Attn: MSAT2...

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Formation of reactive metabolites from benzene

International Nuclear Information System (INIS)

Snyder, R.; Jowa, L.; Witz, G.; Kalf, G.; Rushmore, T.

1986-01-01

Rat liver mitoplasts were incubated first with [ 3 H]dGTP, to form DNA labeled in G, and then with [ 14 C]benzene. The DNA was isolated and upon isopycnic density gradient centrifugation in CsCl yielded a single fraction of DNA labeled with both [ 3 H] and [ 14 C]. These data are consistent with the covalent binding of one or more metabolites of benzene to DNA. The DNA was enzymatically hydrolyzed to deoxynucleosides and chromatographed to reveal at least seven deoxyguanosine adducts. Further studies with labeled deoxyadenine revealed one adduct on deoxyadenine. [ 3 H]Deoxyguanosine was reacted with [ 14 C]hydroquinone or benzoquinone. The product was characterized using uv, fluorescence, mass and NMR spectroscopy. A proposed structure is described. (orig.)

Radiation chemistry of a mixture of benzene and cyclohexane in presence of triphenyl stibine

Energy Technology Data Exchange (ETDEWEB)

Nazir, S B; Rai, R S [Birla Inst. of Tech. and Science, Pilani (India). Dept. of Chemistry

1976-08-01

Following previously reported work (Peterson et al. J. Phys. Chem.; 71: 4506 (1967)) on the radiolysis of triphenyl stibine in benzene from which it was concluded that the energy is absorbed by benzene and excited benzene molecules transfer their energy to the metal phenyl which does not decompose due to quenching and since benzene is a protective agent for cyclohexane against ..gamma.. radiation, a system consisting of benzene, cyclohexane and triphenyl stibine has been used to study the energy transfer processes and the nature of protection. It was found that /sup 60/C0 ..gamma.. radiolysis of cyclohexane in presence of 1 x 10/sup -2/M triphenyl stibine formed two isomers of pentane and hexane and hexene, methylcyclopentane, benzene and cyclohexene. G values of these products, except those of hexene and methylcyclopentane are negligible. All products except these two are eliminated in the radiolysis of this system in presence of benzene. G values of these products are reduced considerably. The mechanism of formation of these compounds and a sponge type protection have been postulated to explain the results.

40 CFR 80.1290 - How are standard benzene credits generated?

Science.gov (United States)

2010-07-01

... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading... approved under § 80.1340. (b) [Reserved] (c)(1) The number of standard benzene credits generated shall be... the nearest gallon. Fractional values shall be rounded down if less than 0.50, and rounded up if...

Mercury migration into ground water, a literature study

Energy Technology Data Exchange (ETDEWEB)

Carlton, W.H.; Carden, J.L.; Kury, R.; Eichholz, G.G.

1994-11-01

This report presents a broad review of the technical literature dealing with mercury migration in the soil. The approach followed was to identify relevant articles by searching bibliographic data bases, obtaining the promising articles and searching these articles for any additional relevant citations. Eight catagories were used to organize the literature, with a review and summary of each paper. Catagories used were the following: chemical states of mercury under environmental conditions; diffusion of mercury vapor through soil; solubility and stability of mercury in environmental waters; transport of mercury on colloids; models for mercury migration through the environment; analytical techniques; retention of mercury by soil components; formation of organomecurials.

29 CFR 1910.1028 - Benzene.

Science.gov (United States)

2010-07-01

...) Scope and application. (1) This section applies to all occupational exposures to benzene. Chemical...-general, and paragraph (e)(6) accuracy of monitoring. Engineering and work practice controls shall be used... wholesale customers. Container means any barrel, bottle, can, cylinder, drum, reaction vessel, storage tank...

Subsurface migration of petroleum hydrocarbons: A case study of immiscible migration and chromatographic separation

International Nuclear Information System (INIS)

Dawson, H.E.

1991-01-01

The subsurface distribution of a leaked crude oil illustrates the combined influence of both the chemical and physical properties of soil and free product on the migration of petroleum hydrocarbons. Immiscible phase behavior was observed, as well as chromatographic-like separation of the lighter constituents of the crude oil from the heavier constituents. After downward migration through approximately 50 ft of unsaturated, heterogeneous alluvial sediments, the crude oil formed a horizontal plume on top of a perched, saturated zone. Immiscible phase trapping is evident from the occurrence of very high concentration of hydrocarbons in both the vertical and horizontal plumes. Samples taken from the vertical zone of contamination indicate a transition from heavier hydrocarbons near the surface to lighter hydrocarbons at depth. This phenomenon is attributed to chromatographic-like separation of the heavier hydrocarbons by the soil, possibly due to preferential solubility of the lighter hydrocarbons in percolating ran water

Benzene levels in ambient air and breath of smokers and nonsmokers in urban and pristine environments

Energy Technology Data Exchange (ETDEWEB)

Wester, R.C.; Maibach, H.I.; Gruenke, L.D.; Craig, J.C.

1986-01-01

Benzene levels in human breath and in ambient air were compared in the urban area of San Francisco (SF) and in a more remote coastal pristine setting of Stinson Beach, Calif. (SB). Benzene analysis was done by gas chromatography-mass spectroscopy (GC-MS). Ambient benzene levels were sevenfold higher in SF (2.6 +/- 1.3 ppb, n = 25) than SB (0.38 +/- 0.39 ppb, n = 21). In SF, benzene in smokers' breath (6.8 +/- 3.0 ppb) was greater than in nonsmokers' breath (2.5 +/- 0.8 ppb) and smokers' ambient air (3.3 +/- 0.8 ppb). In SB the same pattern was observed: benzene in smokers' breath was higher than in nonsmokers' breath and ambient air. Benzene in SF nonsmokers' breath was greater than in SB nonsmokers' breath. Marijuana-only smokers had benzene breath levels between those of smokers and nonsmokers. There was little correlation between benzene in breath and number of cigarettes smoked, or with other benzene exposures such as diet. Of special interest was the finding that benzene in breath of SF nonsmokers (2.5 +/- 0.8 ppb) was greater than that in nonsmokers ambient air (1.4 +/- 0.1 ppb). The same was true in SB, where benzene in nonsmokers breath was greater than ambient air (1.8 +/- 0.2 ppb versus 1.0 +/- 0.1 ppb on d 1 and 1.3 +/- 0.3 ppb versus 0.23 +/- 0.18 ppb on d 2). This suggests an additional source of benzene other than outdoor ambient air.

Muconaldehyde formation from 14C-benzene in a hydroxyl radical generating system

Energy Technology Data Exchange (ETDEWEB)

Latriano, L.; Zaccaria, A.; Goldstein, B.D.; Witz, G.

1985-01-01

It has recently been proposed that muconaldehyde, a six carbon, alpha, beta-unsaturated dialdehyde, may be a hematotoxic metabolite of benzene. The present studies indicate that trans, trans-muconaldehyde is formed from benzene in vitro in a hydroxyl radical (.OH) generating system containing ascorbate, ferrous sulfate and EDTA in phosphate buffer, pH 6.7. Muconaldehyde formed from benzene in the .OH generating system was identified by trapping it with thiobarbituric acid (TBA), which results in the formation of an adduct with a 495 nm absorption maximum and a 510 nm fluorescence emission maximum. These maxima were identical to those observed after reacting authentic trans, trans-muconaldehyde with TBA. This finding was supported by thin layer chromatography and solid phase extraction studies. In those studies benzene-derived muconaldehyde cochromatographed with the muconaldehyde/TBA standard. Analyses of the products from the .OH generating system using high performance liquid chromatography (HPLC) confirm that trans, trans-muconaldehyde is a product of benzene ring fission. Regardless of whether or not TBA was used for trapping, samples from the .OH system incubated with benzene contained a peak which cochromatographed with the muconaldehyde standard. The radioactivity profile of fractions collected during HPLC analysis demonstrates 14C-benzene to be the source of the trans, trans-muconaldehyde. The role of hydroxyl radicals in the formation of muconaldehyde was investigated by using dimethyl sulfoxide, mannitol, and ethanol as .OH scavengers. These scavengers, at concentrations of 10 and 100 mM, were found to cause a dose-dependent decrease in the formation of muconaldehyde.

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

Science.gov (United States)

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

1994-11-01

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

Solubility study of Tc(IV) oxides

International Nuclear Information System (INIS)

Liu, D.J.; Fan, X.H.

2005-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safer disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 ·nH 2 O. Hence, the mobility of Tc(IV) in reducing groundwater may be limited by the solubility of TcO 2 ·nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 ·nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium oxide was prepared by reduction of a technetate solution with Sn 2 + . The solubility of Tc(IV) oxide has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) oxide were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about (1.49-1.86) x 10 -9 mol/(L·d) under aerobic conditions, but Tc(IV) in simulated groundwater and redistilled water is not oxidized under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) oxide in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

Antimalarial activity of compounds comprising a primary benzene sulfonamide fragment.

Science.gov (United States)

Andrews, Katherine T; Fisher, Gillian M; Sumanadasa, Subathdrage D M; Skinner-Adams, Tina; Moeker, Janina; Lopez, Marie; Poulsen, Sally-Ann

2013-11-15

Despite the urgent need for effective antimalarial drugs with novel modes of action no new chemical class of antimalarial drug has been approved for use since 1996. To address this, we have used a rational approach to investigate compounds comprising the primary benzene sulfonamide fragment as a potential new antimalarial chemotype. We report the in vitro activity against Plasmodium falciparum drug sensitive (3D7) and resistant (Dd2) parasites for a panel of fourteen primary benzene sulfonamide compounds. Our findings provide a platform to support the further evaluation of primary benzene sulfonamides as a new antimalarial chemotype, including the identification of the target of these compounds in the parasite. Copyright © 2013 Elsevier Ltd. All rights reserved.

Utilization of alternative fuels and materials in cement kiln towards emissions of benzene, toluene, ethyl-benzene and xylenes (BTEX

Directory of Open Access Journals (Sweden)

Muliane Ulfi

2018-01-01

Full Text Available Co-processing in cement industry has benefits for energy conservation and waste recycling. Nevertheless, emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX tend to increase compared to a non co-processing kiln. A study was conducted in kiln feeding solid AFR (similar to municipal solid waste, MSW having production capacity 4600-ton clinker/day (max. 5000 ton/day and kiln feeding biomass having production capacity 7800-ton clinker/day (max. 8000 ton/day. The concentration of VOCs emissions tends to be higher at the raw mill on rather than the raw mill off. At the raw mill on, concentration of total volatile organic carbon (VOCs emission from cement kiln stack feeding Solid AFR 1, biomass, Solid AFR 2, and mixture of Solid AFR and biomass is 16.18 mg/Nm3, 16.15 mg/Nm3, 9.02 mg/Nm3, and 14.11 mg/Nm3 respectively. The utilization of biomass resulted in the lower fraction of benzene and the higher fraction of xylenes in the total VOCs emission. Operating conditions such as thermal substitution rate, preheater temperature, and kiln speed are also likely to affect BTEX emissions.

Upstream petroleum industry glycol dehydrator benzene emissions status report

International Nuclear Information System (INIS)

1999-07-01

The population of dehydrators referred to are located in the Western Sedimentary Basin in northeast British Columbia, Alberta and Saskatchewan, and includes units installed at wellsites, compressor stations, gas plants, central crude oil treating facilities, and reservoir or salt cavern gas storage facilities. Benzene emissions from the still column vent on glycol dehydrators occur as a result of glycol's strong affinity for aromatic hydrocarbons, including benzene. A study was carried out to: 1) develop a list of oil and gas companies operating in Canada, 2) develop an equipment and benzene emissions inventory of glycol dehydrators, 3) develop a database in Microsoft Access format to gather and maintain inventory and emission data, 4) evaluate and validate at least 10% of the reported data, 5) develop a list of companies that manufacture dehydrators and incinerators to determine how many new dehydrators were sold for use in Canada in 1998, and 6) prepare a report summarizing findings and recommendations. The companies included in the survey were the oil and gas companies identified by the Nickels' Oil and Gas Index and others provided by CAPP, CGA, and SEPAC. The project was carried out to gather glycol dehydrator equipment and still column vent benzene emissions information. 8 refs

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

OpenAIRE

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

2015-01-01

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

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

2004-12-15

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.)

Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.

Science.gov (United States)

Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

2014-01-01

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2 m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. © 2013, National Ground Water Association.

Numerical prediction of 239Pu migration in unsaturated porous media under infiltration scenario

International Nuclear Information System (INIS)

Liu Dongxu; Si Gaohua; Wang Qinghai; Yu Jing

2011-01-01

In terms of the study on site selection of a radioactive waste disposal repository in northwest China, a numerical prediction of 239 Pu migration for potential groundwater pollution in the unsaturated zone was conducted with the HYDRUS-1D model. The results showed that the groundwater will not be contaminated by the migration of soluble 239 Pu. And there is little possibility that 239 Pu migration through groundwater path might have an unacceptable impact on exosphere. Measurements of the distribution coefficient, K d , are critical in the determination of sorption-induced retardation of radionuclide transport. (authors)

Numerical prediction of 239Pu migration for groundwater pollution in the infiltration case

International Nuclear Information System (INIS)

Liu Dongxu; Si Gaohua; Wang Qinghai; Yu Jing

2010-01-01

In terms of the study on site selection of geological disposal of LIL radioactive waste in north-west China, a numerical prediction of 239 Pu migration for potential groundwater pollution in the unsaturated zone was conducted with the HYDRUS-ID model. The results showed that the groundwater will not be contaminated by the migration of soluble 239 Pu. And there is a faint possibility that 239 Pu migration through groundwater path might have an unacceptable impact on ecosphere. Measurements of the distribution coefficient, K d , are critical in the determination of sorption-induced retardation of radionuclide transport. (authors)

Unleaded gasoline with reduction in benzene and aromatics

International Nuclear Information System (INIS)

Ahmed, I.

2003-01-01

The trend today is towards making gasoline more environment and human friendly or in other words making gasoline a really clean fuel. This paper covers the ill effects of benzene and aromatics and the driving force behind their reduction in gasoline worldwide. It addresses health concerns specifically, and the theme is unleaded gasoline without simultaneously addressing reduction in benzene and aromatics is more harmful. The paper cites worldwide case studies, and also the World Bank (WB), Government of Pakistan (GoP), and United Nations (UN) efforts in this area in Pakistan. (author)

Canadian soil quality guidelines for the protection of environmental and human health : benzene

Energy Technology Data Exchange (ETDEWEB)

Potter, K.

2005-07-01

This report presented soil quality guidelines for benzene to protect humans and ecological receptors in 4 types of land uses: agricultural; residential and parklands; commercial and industrial. The chemical and physical properties of benzene were reviewed, as well as the sources and emissions of benzene in Canada. The distribution and behaviour of benzene in the environment was examined, and the toxicological effects of benzene on microbial processes, plants, animals and humans were reviewed. It was noted that the background information and rationale for the derivation of Canadian Soil Quality Guidelines for this substance were originally published in 1999 by the Canadian Council of Ministers of the Environment (CCME) in Canadian Environmental Quality Guidelines. These guidelines have since been revised to reflect new data and lessons learned during the development of the Canada-wide Standard for Petroleum Hydrocarbons in Soil (CCME 2000). Modifications in this report included the derivation of guidelines for different soil textures and depths. Behaviour and effects in biota were reviewed, including soil microbial processes; terrestrial plants; terrestrial invertebrates; livestock and wildlife; and bioaccumulation. Behaviour and effects in humans and mammalian species were examined. The derivation of environmental soil quality guidelines was outlined. Recommendations for Canadian soil quality guidelines were presented. It was concluded that there is a lack of studies on the toxic effects of benzene on livestock, mammalian wildlife and birds and that studies on the metabolism of benzene in mammals and birds as well as invertebrates are needed. In addition, research is needed on the effects of benzene on nitrogen fixation, nitrification, nitrogen mineralization, decomposition and respiration. 118 refs., 3 tabs., 2 figs.

Surface silylation of natural mesoporous/macroporous diatomite for adsorption of benzene.

Science.gov (United States)

Yu, Wenbin; Deng, Liangliang; Yuan, Peng; Liu, Dong; Yuan, Weiwei; Liu, Peng; He, Hongping; Li, Zhaohui; Chen, Fanrong

2015-06-15

Naturally occurring porous diatomite (Dt) was functionalized with phenyltriethoxysilane (PTES), and the PTES-modified diatomite (PTES-Dt) was characterized using diffuse reflectance Fourier transform infrared spectroscopy, nitrogen adsorption, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. After silylation, a functional group (-C6H5, phenyl) was successfully introduced onto the surface of Dt. PTES-Dt exhibited hydrophobic properties with a water contact angle (WCA) as high as 120°±1°, whereas Dt was superhydrophilic with a WCA of 0°. The benzene adsorption data on both Dt and PTES-Dt fit well with the Langmuir isotherm equation. The Langmuir adsorption capacity of benzene on PTES-Dt is 28.1 mg/g, more than 4-fold greater than that on Dt. Moreover, the adsorption kinetics results show that equilibrium was achieved faster for PTES-Dt than for Dt, over the relative pressure range of 0.118-0.157. The excellent benzene adsorption performance of PTES-Dt is attributed to strong π-system interactions between the phenyl groups and the benzene molecules as well as to the macroporosity of the PTES-Dt. These results show that the silylated diatomite could be a new and inexpensive adsorbent suitable for use in benzene emission control. Copyright © 2015 Elsevier Inc. All rights reserved.

Benzene emission from the actual car fleet in relation to petrol composition in Denmark

International Nuclear Information System (INIS)

Palmgren, F.; Hansen, A.B.; Berkowicz, R.; Skov, H.

2001-01-01

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO x from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NO x . The decreasing trends of NO x and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period. (Author)

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

OpenAIRE

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

1994-01-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several inve...

Radiochemical approaches to the migration of elements from a radwaste repository

International Nuclear Information System (INIS)

Guillaumont, R.

1993-01-01

Underground high-level or intermediary-level alpha radwaste repositories will contain tons to hundreds of tons of anthropogenic elements. It is predicted that the release of the elements into the far field will be mainly dependent upon the 'solubilities', sums of the concentrations of soluble species and colloidal/pseudo colloidal forms, of expected near field compounds. On the other hand, safety assessments, based on computation models of migration, show that elements in the discharged water into the biosphere will be at tracer level, or at least, at trace levels. Kinetic and thermodynamic aspects of the processes in which elements will be involved during their migration are discussed together with the change in their concentrations, over several orders of magnitude. It is shown that special attention must be given to predict the behaviour of the elements in the far field from what we know from classical chemistry, and that more experimental data must be obtained to improve the models. (author). 31 refs., 5 figs., 4 tabs

The use of biomonitoring data in exposure and human health risk assessment: benzene case study.

Science.gov (United States)

Arnold, Scott M; Angerer, Juergen; Boogaard, Peter J; Hughes, Michael F; O'Lone, Raegan B; Robison, Steven H; Schnatter, A Robert

2013-02-01

Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10(-5) excess cancer risk (2.9 µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.

The solubility of nickel and its migration through the cementitious backfill of a geological disposal facility for nuclear waste.

Science.gov (United States)

Felipe-Sotelo, M; Hinchliff, J; Field, L P; Milodowski, A E; Holt, J D; Taylor, S E; Read, D

2016-08-15

This work describes the solubility of nickel under the alkaline conditions anticipated in the near field of a cementitious repository for intermediate level nuclear waste. The measured solubility of Ni in 95%-saturated Ca(OH)2 solution is similar to values obtained in water equilibrated with a bespoke cementitious backfill material, on the order of 5×10(-7)M. Solubility in 0.02M NaOH is one order of magnitude lower. For all solutions, the solubility limiting phase is Ni(OH)2; powder X-ray diffraction and scanning transmission electron microscopy indicate that differences in crystallinity are the likely cause of the lower solubility observed in NaOH. The presence of cellulose degradation products causes an increase in the solubility of Ni by approximately one order of magnitude. The organic compounds significantly increase the rate of Ni transport under advective conditions and show measurable diffusive transport through intact monoliths of the cementitious backfill material. Copyright © 2016 Elsevier B.V. All rights reserved.

Monitoring benzene formation from benzoate in model systems by proton transfer reaction-mass spectrometry

Science.gov (United States)

Aprea, Eugenio; Biasioli, Franco; Carlin, Silvia; Märk, Tilmann D.; Gasperi, Flavia

2008-08-01

The presence of benzene in food and in particular in soft drinks has been reported in several studies and should be considered in fundamental investigations about formation of this carcinogen compound as well as in quality control. Proton transfer reaction-mass spectrometry (PTR-MS) has been used here for rapid, direct quantification of benzene and to monitor its formation in model systems related to the use of benzoate, a common preservative, in presence of ascorbic acid: a widespread situation that yields benzene in, e.g., soft drinks and fruit juices. Firstly, we demonstrate here that PTR-MS allows a rapid determination of benzene that is in quantitative agreement with independent solid phase micro-extraction/gas chromatography (SPME/GC) analysis. Secondly, as a case study, the effect of different sugars (sucrose, fructose and glucose) on benzene formation is investigated indicating that they inhibit its formation and that this effect is enhanced for reducing sugars. The sugar-induced inhibition of benzene formation depends on several parameters (type and concentration of sugar, temperature, time) but can be more than 80% in situations that can be expected in the storage of commercial soft drinks. This is consistent with the reported observations of higher benzene concentrations in sugar-free soft drinks.

High pressure photoinduced ring opening of benzene

International Nuclear Information System (INIS)

Ciabini, Lucia; Santoro, Mario; Bini, Roberto; Schettino, Vincenzo

2002-01-01

The chemical transformation of crystalline benzene into an amorphous solid (a-C:H) was induced at high pressure by employing laser light of suitable wavelengths. The reaction was forced to occur at 16 GPa, well below the pressure value (23 GPa) where the reaction normally occurs. Different laser sources were used to tune the pumping wavelength into the red wing of the first excited singlet state S 1 ( 1 B 2u ) absorption edge. Here the benzene ring is distorted, presenting a greater flexibility which makes the molecule unstable at high pressure. The selective pumping of the S 1 level, in addition to structural considerations, was of paramount importance to clarify the mechanism of the reaction

Positronium quenching in liquid and solid octanol and benzene

DEFF Research Database (Denmark)

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

1970-01-01

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.......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....

Benzene-induced genotoxicity in mice in vivo detected by the alkaline comet assay

DEFF Research Database (Denmark)

Tuo, J; Loft, S; Thomsen, M S

1996-01-01

was further increased to 5.4-fold and 6.6-fold of the control values, respectively (p propylene glycol (5 microliters/g b.wt., twice with a 60-min interval), a selective CYP2E1 inhibitor, reduced the increase in the tail length by about half at all doses in both cell types (p ...The myelotoxic and genotoxic effects of benzene have been related to oxidative DNA damage after metabolism by CYP2E1. Single cell gel electrophoresis (alkaline comet assay) detects DNA damage and may thus be a convenient method for the study of benzene genotoxicity. Benzene exposure to NMRI mice.......01). By comparing our data with those from genotoxicity studies on benzene using other methods, we conclude that the 'alkaline comet assay' is a sensitive method to detect DNA damage induced by benzene. We also infer that CYP2E1 contributes, at least partly, to the formation of the 'comet'-inducing metabolites...

Removal efficiencies of constructed wetland and efficacy of plant on treating benzene

Directory of Open Access Journals (Sweden)

Florencio Ballesteros, Jr.

2016-03-01

Full Text Available Leaking underground petroleum storage poses human and environmental health risks as it contaminates the soil and the groundwater. Of the many contaminants, benzene – a major constituent of gasoline, is of primary concern. It is an identified carcinogen with a permissible limit set at a low level of 0.005 mg L−1. This poses technical and regulatory challenge to remediation of contaminated sites. Various specialized treatment methods are available, but despite of the high removal efficiencies of sophisticated treatments, the residual level still poses health risks. Thus, additional alternative ways that are cost effective and require minimum technical expertise are necessary, and a constructed wetland (CW is a potential alternative. This study evaluates the performance of a surface flow type CW for the removal of benzene from the contaminated water. It further determines the efficacy of a common reed plant Phragmites karka in treating benzene. Planted and unplanted CW were acclimated with benzene for 16 wk and tested for an 8-d hydraulic retention time at benzene levels of 66 and 45 mg L−1. Results indicate that the planted CW performed better and gave reliable and stable results.

The enhanced spin-polarized transport behaviors through cobalt benzene-porphyrin-benzene molecular junctions: the effect of functional groups

Science.gov (United States)

Cheng, Jue-Fei; Zhou, Liping; Wen, Zhongqian; Yan, Qiang; Han, Qin; Gao, Lei

2017-05-01

The modification effects of the groups amino (NH2) and nitro (NO2) on the spin polarized transport properties of the cobalt benzene-porphyrin-benzene (Co-BPB) molecule coupled to gold (Au) nanowire electrodes are investigated by the nonequilibrium Green’s function method combined with the density functional theory. The calculation results show that functional groups can lead to the significant spin-filter effect, enhanced low-bias negative differential resistance (NDR) behavior and novel reverse rectifying effect in Co-BPB molecular junction. The locations and types of functional groups have distinct influences on spin-polarized transport performances. The configuration with NH2 group substituting H atom in central porphyrin ring has larger spin-down current compared to that with NO2 substitution. And Co-BPB molecule junction with NH2 group substituting H atom in side benzene ring shows reverse rectifying effect. Detailed analyses confirm that NH2 and NO2 group substitution change the spin-polarized transferred charge, which makes the highest occupied molecular orbitals (HOMO) of spin-down channel of Co-BPB closer to the Fermi level. And the shift of HOMO strengthens the spin-polarized coupling between the molecular orbitals and the electrodes, leading to the enhanced spin-polarized behavior. Our findings might be useful in the design of multi-functional molecular devices in the future.

The use of biomonitoring data in exposure and human health risk assessment: benzene case study

Science.gov (United States)

Angerer, Juergen; Boogaard, Peter J.; Hughes, Michael F.; O’Lone, Raegan B.; Robison, Steven H.; Robert Schnatter, A.

2013-01-01

A framework of “Common Criteria” (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m3), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10−5 excess cancer risk (2.9 µg/m3). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects. PMID:23346981

(Liquid + liquid) equilibria of {benzene + cyclohexane + two ionic liquids} at different temperature and atmospheric pressure

International Nuclear Information System (INIS)

Sakal, Salem A.; Shen, Chong; Li, Chun-xi

2012-01-01

Highlights: ► (Liquid + liquid) equilibrium for two quaternary and two ternary systems were measured. ► The components include cyclohexane, benzene, [MIM][BF4], [MIM][ClO4] and [MMIM][DMP]. ► The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. ► Separation of benzene and cyclohexane by pure ILs and their mixtures were discussed. - Abstract: (Liquid + liquid) equilibrium data of the following ternary and quaternary systems at different temperatures and mass fractions of ionic liquids (ILs) were measured at atmospheric pressure, i.e., {cyclohexane + benzene + 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP])} at 298.2 K, {cyclohexane + benzene + 1-methylimidazolium tetrafluoroborate ([MIM][BF 4 ])} at 338.2 K, {cyclohexane + benzene + [MIM][BF 4 ] + [MMIM][DMP]} at (298.2 and 313.2) K, and {cyclohexane + benzene + 1-methylimidazolium perchlorate [MIM][ClO 4 ] + [MMIM][DMP]} at 298.2 K. The results indicate that both selectivity and distribution factor of the IL mixture for benzene are lower than that of pure IL [MMIM][DMP] at a specified condition, and decrease with the increase of the mass fraction of [MIM][BF 4 ] or [MIM][ClO 4 ] in its mixture of [MMIM][DMP] and the mole fraction of benzene. The extremely high selectivity of [MIM][BF 4 ] and [MIM][ClO 4 ] for aromatic compounds as predicted by the COSMOS-RS model is not justified by the present experimental results, and on the contrary, they show a relatively lower selectivity and extraction capacity for benzene than [MMIM][DMP].

Modelling migration in multilayer systems by a finite difference method: the spherical symmetry case

International Nuclear Information System (INIS)

Hojbota, C I; Toşa, V; Mercea, P V

2013-01-01

We present a numerical model based on finite differences to solve the problem of chemical impurity migration within a multilayer spherical system. Migration here means diffusion of chemical species in conditions of concentration partitioning at layer interfaces due to different solubilities of the migrant in different layers. We detail here the numerical model and discuss the results of its implementation. To validate the method we compare it with cases where an analytic solution exists. We also present an application of our model to a practical problem in which we compute the migration of caprolactam from the packaging multilayer foil into the food

Separation of several alcohol-benzene mixtures by pervaporation through styrene graft polyethylene membranes

International Nuclear Information System (INIS)

Murata, Kenichi

1989-01-01

The permeation of pure liquids, such as methanol, ethanol, 1-propanol, 2-propanol and benzene, and the permeability and selectivity of 50 vol% binary mixtures of these alcohols and benzene were investigated by pervaporation technique. The used membranes (21%, 40%, and 72% graftings) were obtained by graft polymerization of styrene to polyethylene film (thickness 10 μm) by γ-radiation. The permeation rates of each of these alcohols and benzene were measured by pervaporation through the graft membranes. Those of these alcohols were very small as well as those through the original membrane. On the other hand, the permeabilities for benzene through the graft membranes were larger than that through the original membrane. The temperature dependence of the permeation rate for benzene was expressed by Arrhenius-type relationships, and the apparent activation energies were calculated to be 10.7 (21%), 10.2 (40%) and 10.0 (72%) kcal/mol. In the permeation of 50 vol% several alcohol-benzene mixtures, the permeabilities through the graft membranes were also larger than that through the original membrane, and increased with the grafting. The temperature dependence of the permeation for these mixtures was showed by Arrhenius relationships, and the apparent activation energies were calculated to be in the range of 8.4∼11.0 kcal/mol. The separation factors of the graft membranes calculated from composition of the permeates were always smaller than that of the original membrane, but became larger with increase of molecular volume of alcohol in alcohol-benzene mixtures. (author)

Combined analysis of job and task benzene air exposures among workers at four US refinery operations.

Science.gov (United States)

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

2017-03-01

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.

Effect Factors of Benzene Adsorption and Degradation by Nano-TiO2 Immobilized on Diatomite

Directory of Open Access Journals (Sweden)

Lijun Cheng

2012-01-01

Full Text Available Difference between adsorption of benzene by diatomite and nano-TiO2 immobilized on diatomite was investigated. And effects of temperature, light intensity, relative humidity, and initial benzene concentration on adsorption and degradation of benzene by nano-TiO2 immobilized on diatomite were also studied. The experimental results showed that when initial benzene concentration was 2.2×10−3 mg L−1, it could be degraded to below safe concentration (1.1×10−4 mg L−1 after 50 h when temperature was 20°C, but it just needed 30 h at 35°C. When light intensity was 6750 Lx, it needed 30 h for benzene to be degraded to below safe concentration, but benzene could barely be degraded without light. When relative humidity was 50%, benzene could be degraded to 1.0×10−4 mg L−1 after 30 h, while its concentration could be reduced to 7.0×10−5 mg L−1 at the relative humidity of 80%.

40 CFR 80.1235 - What gasoline is subject to the benzene requirements of this subpart?

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What gasoline is subject to the... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1235 What gasoline is subject to the benzene requirements of...

Evaluation of accelerated UV and thermal testing for benzene formation in beverages containing benzoate and ascorbic acid.

Science.gov (United States)

Nyman, Patricia J; Wamer, Wayne G; Begley, Timothy H; Diachenko, Gregory W; Perfetti, Gracia A

2010-04-01

Under certain conditions, benzene can form in beverages containing benzoic and ascorbic acids. The American Beverage Assn. (ABA) has published guidelines to help manufacturers mitigate benzene formation in beverages. These guidelines recommend accelerated testing conditions to test product formulations, because exposure to ultraviolet (UV) light and elevated temperature over the shelf life of the beverage may result in benzene formation in products containing benzoic and ascorbic acids. In this study, the effects of UVA exposure on benzene formation were determined. Benzene formation was examined for samples contained in UV stabilized and non-UV stabilized packaging. Additionally, the usefulness of accelerated thermal testing to simulate end of shelf-life benzene formation was evaluated for samples containing either benzoic or ascorbic acid, or both. The 24 h studies showed that under intense UVA light benzene levels increased by as much as 53% in model solutions stored in non-UV stabilized bottles, whereas the use of UV stabilized polyethylene terephthalate bottles reduced benzene formation by about 13% relative to the non-UV stabilized bottles. Similar trends were observed for the 7 d study. Retail beverages and positive and negative controls were used to study the accelerated thermal testing conditions. The amount of benzene found in the positive controls and cranberry juice suggests that testing at 40 degrees C for 14 d may more reliably simulate end of shelf-life benzene formation in beverages. Except for cranberry juice, retail beverages were not found to contain detectable amounts of benzene (<0.05 ng/g) at the end of their shelf lives.

Consideration on thermodynamic data for predicting solubility and chemical species of elements in groundwater. Part 1: Tc, U, Am

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Tetsuji; Takeda, Seiji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1999-01-01

The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Complexations of radionuclides by ligands in groundwater affect the interaction between radionuclides and geologic media, thus affect their migration behavior. Thermodynamic data for Tc, Am and U were reviewed and compiled to be used for predicting the solubility and chemical species in groundwater. Thermodynamic data were reviewed with emphasis on the hydrolysis and carbonate complexation that can dominate the speciation in typical groundwater. Thermodynamic data for other species were selected based on existing database. Thermodynamic data for other important elements are under investigation, thus shown in an appendix for temporary use. (author)

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

Directory of Open Access Journals (Sweden)

Werner Tirler

2015-03-01

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.

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

Science.gov (United States)

Tirler, Werner; Settimo, Gaetano

2015-01-01

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. 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. 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/m of benzene in the test room after the incense sticks had been tested.

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

Science.gov (United States)

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

2016-09-01

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

Catalytic transformation of methyl benzenes over zeolite catalysts

KAUST Repository

Al-Khattaf, S.

2011-02-01

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

Use of electrical tomography methods to determinate the extension and main migration routes of uncontrolled landfill leachates in fractured areas

Energy Technology Data Exchange (ETDEWEB)

Casado, Ismael, E-mail: iscaferr@gmail.com [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Department of Geology and Environmental Earth Science, Miami University, 501 East High Street, 45056 Oxford, OH (United States); Mahjoub, Himi [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Ecole Nationale des Sciences Appliquées d' Al Hoceima (ENSAH), University Mohammed Premier, Ajdir, Al Hoceima (Morocco); Lovera, Raul [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Fernández, Jesús, E-mail: jfernandezc@aragon.es [Department of Agriculture, Ranching and Environment, Diputación General de Aragon (DGA), Plaza de San Pedro Nolasco, 7, 50071 Zaragoza (Spain); Casas, Albert [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain)

2015-02-15

This study focuses on the uses of the electrical tomography and its relationship with hydrochemical data in order to characterize contaminated groundwater flows in fractured aquifers. The studied area is contaminated with different hazardous substances like lyndanes, organochlorinated compounds and benzenes coming from the old non-controlled Sardas landfill. The enormous volumes of wastes filling the landfill have generated a convoluted mixture of leachates. Due to the lack of a landfill liner, the leachates have migrated through the fractured Eocene marls towards the Gallego River. The striking correlation between high concentrations of polluted groundwater and low electrical resistivity of the subsurface (< 8 Ω·m) allows defining the principal contaminant migration route thanks to the distribution of these conductive anomalies. This mapping verifies that there is intense tectonical–structural control of the leachate migration, because the deep migration presents the same direction as the geological axis fold. - Highlights: • The outcrop topographic reconstruction is done using cores and aerial photographs. • Hydrochemical and geophysical data allow defining two leachate migration paths. • Conductive anomalies in ERT are linked to high contaminant concentration. • The distribution of conductive anomalies defines the fractured basement migration. • The plume direction reflects important tectonic control in the migration process.

A comprehensive study of benzene concentrations and emissions in Houston

Science.gov (United States)

Müller, Markus; Eichler, Philipp; Berk Knighton, W.; Estes, Mark; Crawford, James H.; Mikoviny, Tomas; Wisthaler, Armin

2014-05-01

The Houston Metropolitan Area (Greater Houston) has a population of over 6 million people, it ranks among the three fastest growing metropolises in the developed world and population growth scenarios predict it to reach megacity status in the coming two to four decades. Greater Houston is home to the largest petrochemical-manufacturing complex in the world with important consequences for the environment in the region. Direct and fugitive emissions of hydrocarbons adversely affect Houston's air quality which has been subject to intense studies over the past two decades. In 2013, NASA conducted the DISCOVER-AQ field campaign in support of developing a satellite-based capability to assess Houston's air quality in the future. Amongst other measurements, airborne, mobile ground-based and stationary ground-based measurements of benzene were carried out. Benzene is a carcinogenic air toxic with strict exposure regulations in the U.S. and in Europe. We have used the obtained comprehensive dataset to map benzene concentrations in the Houston metropolitan area, locate and identify point sources, compare industrial and traffic emissions and put them in relation to previous measurements and emission inventories. The obtained data will allow a better assessment of health risks associated with benzene exposure in a large metropolitan area that includes both traffic and industrial benzene sources. This work was funded by BMVIT / FFG-ALR in the frame of the Austrian Space Application Programme (ASAP 8, project 833451). PE was funded through the PIMMS ITN (EU-FP7, agreement number 287382). Additional resources were provided through NASA's Earth Venture program (EV-1) and the NASA Postdoctoral Program (NPP). We want to thank Scott Herndon and Aerodyne Research for their support.

Benzene degradation in a denitrifying biofilm reactor : activity and microbial community composition

NARCIS (Netherlands)

van der Waals, Marcelle J.; Atashgahi, Siavash; da Rocha, Ulisses Nunes; van der Zaan, Bas M.; Smidt, Hauke; Gerritse, Jan

2017-01-01

Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more than

Solubility of hydrogen isotopes in stressed hydride-forming metals

International Nuclear Information System (INIS)

Coleman, C.E.; Ambler, J.F.R.

1983-01-01

Components made from hydride-forming metals can be brittle when particles of hydride are present. The solid solubility limit of hydrogen in these metals needs to be known so that fracture resistance can be properly assessed. Stress affects the solubility of hydrogen in metals. As hydrogen dissolves the metal volume increases, an applied hydrostatic tensile stress supplies work to increase the solubility. Precipitation of hydrides increases the volume further. A hydrostatic tensile stress promotes the formation of hydrides and tends to reduce the terminal solubility. For materials containing hydrogen in solution in equilibrium with hydrides, the effect of stress on the terminal solubility is given. Hydrogen migrates up tensile stress gradients because of the effect of stress on the solubility and solubility limit. Consequently, hydrogen concentrates at flaws. When hydrides are present in the metal matrix, those remote from the flaw tip will preferentially dissolve in favor of those precipitated at the flaw. If the stress is large enough, at some critical condition the hydrides at the flaw will crack. This is delayed hydrogen cracking. Notched and fatigue-cracked cantilever beam specimens (6) (38 x 4 x 3 mm) were machined from the circumferential direction of several cold-worked Zr-2.5 at. % Nb pressure tubes. The chemical compositions had the ranges (in atomic %) Nb - 2.5 to 2.7; O - 0.58 to 0.71; H - 0.018 to 0.18. The effect of test temperature is for a specimen containing 0.13 at. % protium and 0.29 at .% deuterium. Between 505 K and 530 K was less than 1 hr, between 530 K and 537 K it increased to 25.8 h, while at 538 K no cracking was observed up to the 54 h

Consideration on thermodynamic data for predicting solubility and chemical species of elements in groundwater. Part 2: Np, Pu

International Nuclear Information System (INIS)

Yamaguchi, Tetsuji

2000-11-01

The solubility determines the release of a radionuclide from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Complexations of the radionuclide by ligands in groundwater affect the interaction between radionuclides and geologic media, thus affect their migration behavior. It is essential to estimate the solubility and to predict the chemical species for the radionuclide based on thermodynamic data. The thermodynamic data of aqueous species and compounds were reviewed and compiled for Np and Pu. Thermodynamic data were reviewed with emphasis on the hydrolysis and carbonate complexation that can dominate the speciation in groundwater. Thermodynamic data for other species were selected based on existing databases. Thermodynamic data for other important elements are under investigation, thus shown in an appendix for temporary use. (author)

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

Science.gov (United States)

Hassan, Ashraf Aly; Sorial, George A

2010-12-15

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

Remediation of soils combining soil vapor extraction and bioremediation: benzene.

Science.gov (United States)

Soares, António Alves; Albergaria, José Tomás; Domingues, Valentina Fernandes; Alvim-Ferraz, Maria da Conceição M; Delerue-Matos, Cristina

2010-08-01

This work reports the study of the combination of soil vapor extraction (SVE) with bioremediation (BR) to remediate soils contaminated with benzene. Soils contaminated with benzene with different water and natural organic matter contents were studied. The main goals were: (i) evaluate the performance of SVE regarding the remediation time and the process efficiency; (ii) study the combination of both technologies in order to identify the best option capable to achieve the legal clean up goals; and (iii) evaluate the influence of soil water content (SWC) and natural organic matter (NOM) on SVE and BR. The remediation experiments performed in soils contaminated with benzene allowed concluding that: (i) SVE presented (a) efficiencies above 92% for sandy soils and above 78% for humic soils; (b) and remediation times from 2 to 45 h, depending on the soil; (ii) BR showed to be an efficient technology to complement SVE; (iii) (a) SWC showed minimum impact on SVE when high airflow rates were used and led to higher remediation times for lower flow rates; (b) NOM as source of microorganisms and nutrients enhanced BR but hindered the SVE due the limitation on the mass transfer of benzene from the soil to the gas phase. (c) 2010 Elsevier Ltd. All rights reserved.

Information draft on the development of air standards for isopropyl benzene

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-01-01

Isopropyl benzene, also commonly referred to as cumene, is a colourless liquid with a sharp, penetrating odour. It is derived from the distillation of coal tar, naphtha and petroleum. It is used mainly as an intermediate in the production of phenol, acetone, and alpha-methyl styrene, all of which are components in plastic resins. Isopropyl benzene is also used as a solvent and thinner for paints and enamels and as an octane booster in aviation gasoline. In 1996, reported atmospheric releases in Canada amounted to 16.4 tonnes, of which 9.1 tonnes were from Ontario sources. Isopropyl benzene is not a significant threat to health in low concentrations. Inhalation exposure can cause dizziness, light-headedness and fainting. Contact with isopropyl benzene can irritate the skin, eyes, nose and mouth. The current Ontario half-hour interim Point of Impingement (OPI) standard and the one-hour Ambient Air Quality Criterion (AAQC) are both set at 100 microgram/cubic meter on the basis of the odour nuisance property of the substance. A review of applicable literature from world-wide sources (and summarized in this report) reveal that four US agencies have developed air quality criteria for isopropyl benzene based on the health effects of the compound. These criteria range from 9 to 585 micrograms/cubic meter for an annual average basis and from 87 to 400 microgram/cubic meter on a 24-hour basis. 40 refs., 1 tab., appendix.

Acute myeloid and chronic lymphoid leukaemias and exposure to low-level benzene among petroleum workers

Science.gov (United States)

Rushton, L; Schnatter, A R; Tang, G; Glass, D C

2014-01-01

Background: High benzene exposure causes acute myeloid leukaemia (AML). Three petroleum case–control studies identified 60 cases (241 matched controls) for AML and 80 cases (345 matched controls) for chronic lymphoid leukaemia (CLL). Methods: Cases were classified and scored regarding uncertainty by two haematologists using available diagnostic information. Blinded quantitative benzene exposure assessment used work histories and exposure measurements adjusted for era-specific circumstances. Statistical analyses included conditional logistic regression and penalised smoothing splines. Results: Benzene exposures were much lower than previous studies. Categorical analyses showed increased ORs for AML with several exposure metrics, although patterns were unclear; neither continuous exposure metrics nor spline analyses gave increased risks. ORs were highest in terminal workers, particularly for Tanker Drivers. No relationship was found between benzene exposure and risk of CLL, although the Australian study showed increased risks in refinery workers. Conclusion: Overall, this study does not persuasively demonstrate a risk between benzene and AML. A previously reported strong relationship between myelodysplastic syndrome (MDS) (potentially previously reported as AML) at our study's low benzene levels suggests that MDS may be the more relevant health risk for lower exposure. Higher CLL risks in refinery workers may be due to more diverse exposures than benzene alone. PMID:24357793

Homolytic iodination and nitration of some benzene derivatives in the gas phase

International Nuclear Information System (INIS)

Vonk, W.F.M.

1980-01-01

Two gas phase reactions, involving the iodination and nitration of benzene derivatives, are described. The experimental techniques of the apparatus and the methods used are outlined. The kinetic H/D isotope effect in the gas phase nitration of benzene with NO 2 is determined. (C.F.)

Synthesis of dodecyl lauroyl benzene sulfonate and its application in enhanced oil recovery

Energy Technology Data Exchange (ETDEWEB)

Cui, Zhenggang; Wu, Le; Sun, Mingming; Jiang, Jian-zhong; Wang, Feng [Jiangnan Univ., Wuxi (China). School of Chemical and Material Engineering

2011-09-15

A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl{sub 3}, followed by sulfonation with ClSO{sub 3}H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by1HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45 C. It is highly surface active which is indicated by its low CMC of 1.1 . 10{sup -5} mol/L, and its low surface tension, {gamma}{sub cmc} of 28.6 mN m{sup -1}. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387g mol{sup -1}) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10{sup -3} mN/m at 45 C in the presence of 0.5-1.0 wt.% NaOH and 1000 mg L{sup -1} of polymer. If the NaOH was replaced by a gentle alkaline salt, Na{sub 2}CO{sub 3}, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na{sub 2}CO{sub 3} was increased to 1.2-2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na{sub 2}CO{sub 3} as alkaline agents. (orig.)

Sorption of phenanthrene and benzene on differently structural kerogen: important role of micropore-filling.

Science.gov (United States)

Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

2014-02-01

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2007-07-01

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

Charge transfer from TiO2 into adsorbed benzene diazonium compounds

Science.gov (United States)

Merson, A.; Dittrich, Th.; Zidon, Y.; Rappich, J.; Shapira, Yoram

2004-08-01

Electron transfer from sol-gel-prepared TiO2 into adsorbed benzene diazonium compounds has been investigated using cyclic voltammetry, x-ray photoelectron spectroscopy, contact potential difference, and surface photovoltage spectroscopy. The results show that the potential of maximum electron transfer depends strongly on the dipole moment of the benzene compound. Two reactive surface sites at which electron transfer occurs have been identified.

Methanesulfonic acid (MSA) migration in polar ice: data synthesis and theory

Science.gov (United States)

Osman, Matthew; Das, Sarah B.; Marchal, Olivier; Evans, Matthew J.

2017-11-01

Methanesulfonic acid (MSA; CH3SO3H) in polar ice is a unique proxy of marine primary productivity, synoptic atmospheric transport, and regional sea-ice behavior. However, MSA can be mobile within the firn and ice matrix, a post-depositional process that is well known but poorly understood and documented, leading to uncertainties in the integrity of the MSA paleoclimatic signal. Here, we use a compilation of 22 ice core MSA records from Greenland and Antarctica and a model of soluble impurity transport in order to comprehensively investigate the vertical migration of MSA from summer layers, where MSA is originally deposited, to adjacent winter layers in polar ice. We find that the shallowest depth of MSA migration in our compilation varies over a wide range (˜ 2 to 400 m) and is positively correlated with snow accumulation rate and negatively correlated with ice concentration of Na+ (typically the most abundant marine cation). Although the considered soluble impurity transport model provides a useful mechanistic framework for studying MSA migration, it remains limited by inadequate constraints on key physico-chemical parameters - most notably, the diffusion coefficient of MSA in cold ice (DMS). We derive a simplified version of the model, which includes DMS as the sole parameter, in order to illuminate aspects of the migration process. Using this model, we show that the progressive phase alignment of MSA and Na+ concentration peaks observed along a high-resolution West Antarctic core is most consistent with 10-12 m2 s-1 values previously estimated from laboratory studies. More generally, our data synthesis and model results suggest that (i) MSA migration may be fairly ubiquitous, particularly at coastal and (or) high-accumulation regions across Greenland and Antarctica; and (ii) can significantly change annual and multiyear MSA concentration averages. Thus, in most cases, caution should be exercised when interpreting polar ice core MSA records, although records

Benzene oxidation at diamond electrodes: comparison of microcrystalline and nanocrystalline diamonds.

Science.gov (United States)

Pleskov, Yu V; Krotova, M D; Elkin, V V; Varnin, V P; Teremetskaya, I G; Saveliev, A V; Ralchenko, V G

2012-08-27

A comparative study of benzene oxidation at boron-doped diamond (BDD) and nitrogenated nanocrystalline diamond (NCD) anodes in 0.5 M K(2)SO(4) aqueous solution is conducted by using cyclic voltammetry and electrochemical impedance spectroscopy. It is shown by measurements of differential capacitance and anodic current that during the benzene oxidation at the BDD electrode, adsorption of a reaction intermediate occurs, which partially blocks the electrode surface and lowers the anodic current. At the NCD electrode, benzene is oxidized concurrently with oxygen evolution, a (quinoid) intermediate being adsorbed at the electrode. The adsorption and the electrode surface blocking are reflected in the impedance-frequency and impedance-potential complex-plane plots. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Directory of Open Access Journals (Sweden)

Edward R. T. Tiekink

2010-03-01

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.

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, van B.; Groten, J.P.

2005-01-01

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

Effect of in vivo exposure to benzene on the characteristics of bone marrow adherent cells

Energy Technology Data Exchange (ETDEWEB)

Garnett, H M; Cronkite, E P; Drew, R T

1983-01-01

The effect of benzene on the adherent cell population, cultured from the bone marrow of exposed mice was investigated in the presence and absence of hydrocortisone. The adherent CFUs from exposed animals did not differ either in numbers or self-replicate ability to those derived from shown exposed animals. Adherent layers from mice exposed to 100 or 400 pp-benzene were devoid of fat cells regardless of the presence or absence of hydrocortisone. Hydrocortisone was shown to influence the proportion of acid phosphatase-positive cells derived from benzene-exposed animals. Those results suggest that benzene exposure may influence the bone marrow stromal cells.

Sensitivity Enhancement of Benzene Sensor Using Ethyl Cellulose-Coated Surface-Functionalized Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Thanattha Chobsilp

2018-01-01

Full Text Available A hybrid sensor based on the integration of functionalized multiwalled carbon nanotubes (MWCNTs with ethyl cellulose (EC was fabricated for sensitivity enhancement of benzene detection. To functionalize the surface of MWCNTs, MWCNTs were treated with hydrochloric acid for 60 min (A60-MWCNTs, while other MWCNTs were treated with oxygen plasma for 30, 60, 90, and 120 min (P30-MWCNTs, P60-MWCNTs, P90-MWCNTs, and P120-MWCNTs, resp.. Pristine MWCNTs, A-MWCNTs, and P-MWCNTs were dispersed in 1,2-dichloroethane, then dropped onto a printed circuit board consisting of Cu/Au electrodes used as the sensor platform. Next, EC was separately spin coated on the pristine MWCNTs, A-MWCNTs, and P-MWCNTs (EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs, resp.. All sensors responded to benzene vapor at room temperature by increasing their electrical resistance which was sensitive to benzene vapor. The EC/P90-MWCNTs enabled an approximately 11-fold improvement in benzene detection compared to EC/MWCNTs. The sensitivity of all sensors would be attributed to the swelling of EC, resulting in the loosening of the MWCNT network after benzene vapor exposure. The differences of the sensing responses of the EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs would be ascribed to the differences in crystallinity and functionalization of MWCNT sidewalls, suggesting that acid and oxygen plasma treatments of MWCNTs would be promising techniques for the improvement of benzene detection.

Computed structure of small benzene clusters

NARCIS (Netherlands)

van de Waal, B.W.

1986-01-01

The structures of small benzene clusters (C6H6)n, n = 2–7, have been calculated employing potential-energy minimization with respect to molecular translational and rotational coordinates, using exp-6-1 non-bonded atom-atom potential functions. The influence of the adopted point-charge model is

GIS-based assessment of cancer risk due to benzene in Tehran ambient air.

Science.gov (United States)

Atabi, Farideh; Mirzahosseini, Seyed Alireza Hajiseyed

2013-10-01

The present study aimed to assess the risk of cancer due to benzene in the ambient air of gas stations and traffic zones in the north of Tehran. The cancer risk was estimated using the population distribution data for benzene levels and the unit risk for benzene proposed by the United States Environmental Protection Agency (US EPA). Sixteen sampling locations were monitored, once every week, during 5 April 2010 to 25 March 2011. The results showed that the mean annual benzene concentration was 14.51±3.17 parts per billion (ppb) for traffic zones and 29.01±1.32 ppb for outside gas stations. The risk calculated was 1026×10(-6) for gas station 27 and 955×10(-6) for gas station 139. According to our results, the annual benzene level in Tehran ambient air is 2 to 20 times higher than the respective value specified in International Standard (1.56 ppb). Moreover, the results showed a notable increase of cancer risks, ranging from 10% to 56%, for the vicinity population close to the gas stations in comparison to the vicinity population in the traffic zones.

Comparison of measurement methods for benzene and toluene

Science.gov (United States)

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

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

Adsorption of Benzene by “Green” functionalization of Montmorillonite

Directory of Open Access Journals (Sweden)

Anjum Hirra

2018-01-01

Full Text Available The capacity of organically modified Montmorillonite (MMT clay to adsorb nonpolar organic compound (benzene in an aqueous solution, was investigated under the batch process. MMT was pretreated (centrifuged and then functionalized with green intercalating agent i.e. 1-hexyl-3-methyl imadazolium chloride [HMim][Cl]. The characterization through Fourir Transoform Infrared Spectroscopy (FTIR, Differential Scanning Calorimeter (DSC and Field Emission Scanning Electron Microscope (FE-SEM confirmed the presence of the oxygen containing functional groups, changes in melting point and variation in the morphological properties. The governing parameters for the sorption of benzene such as the effect of contact time, pH, adsorbent dose and rotation were studied. The kinetic data conformed to pseuodo 2nd order kinetic model and the isotherm experimental data were a better fit to Langmuir model with maximum adsorption capacity of 588.23mg/g under experimental conditions. Overall, MMT intercalated with 1-hexyl-3-methyl imadazolium chloride is a promising environmental friendly adsorbent for the abatement of benzene in an aqueous solution.

Benzene exposure assessed by metabolite excretion in Estonian oil shale mineworkers: influence of glutathione s-transferase polymorphisms

DEFF Research Database (Denmark)

Sørensen, Mette; Poole, Jason; Autrup, Herman

2004-01-01

Measurement of urinary excretion of the benzene metabolites S-phenylmercapturic acid (S-PMA) and trans,trans-muconic acid (t,t-MA) has been proposed for assessing benzene exposure, in workplaces with relatively high benzene concentrations. Excretion of S-PMA and t,t-MA in underground workers...... the last shift of the week. Personal benzene exposure was 114 +/- 35 mug/m(3) in surface workers (n = 15) and 190 +/- 50 mug/m(3) in underground workers (n = 15) in measurements made prior to the study. We found t,t-MA excretion to be significantly higher in underground workers after the end of shifts 1...... of benzene metabolites as biomarkers for assessment of exposure at modest levels and warrant for further investigations of health risks of occupational benzene exposure in shale oil mines....

Accumulation of chlorinated benzenes in earthworms

Science.gov (United States)

Beyer, W.N.

1996-01-01

Chlorinated benzenes are widespread in the environment. Hexachlorobenzene, pentachlorobenzene and all isomers of dichlorobenzenes, trichlorobenzenes, and tetrachlorobenzenes, have been detected in fish, water, and sediments from the Great Lakes. This paper describes a long-term (26 week) experiment relating the concentrations of chlorinated benzenes in earthworms to 1) the length of exposure, and it describes three 8-week experiments relating concentrations of chlorinated benzenes in earthworms to 2) their concentration in soil 3) the soil organic matter content and, 4) the degree of chlorination. In the 26-week experiment, the concentration of 1,2,4 - trichlorobenzene in earthworms fluctuated only slightly about a mean of 0.63 ppm (Fig. 1). Although a statistically significant decrease can be demonstrated over the test (Pearson correlation coefficient, r = -0.62 p earthworms showed a cyclical trend that coincided with replacement of the media, and a slight but statistically significant tendency to increase from about 2 to 3 ppm over the 26 weeks (r = 0.55, p earthworms increased as the concentrations in the soil increased (Fig. 2), but leveled off at the highest soil concentrations. The most surprising result of this study was the relatively low concentrations in earthworms compared to those in soils. The average concentration of each of the six isomers of trichlorobenzene and tetrachlorobenzene in earthworms was only about 1 ppm (Table 2); the isomeric structure did not affect accumulation. The concentration of organic matter in soil had a prominent effect on hexachlorobenzene concentrations in earthworms (Fig. 3). Hexachlorobenzene concentrations decreased steadily from 9.3 ppm in earthworms kept in soil without any peat moss added to about 1 ppm in soil containing 16 or 32% organic matter.

An investigation of 2,5-di-tertbutyl-1,4-bis(methoxyethoxy)benzene in ether-based electrolytes

Energy Technology Data Exchange (ETDEWEB)

Su, Liang; Ferrandon, Magali; Barton, John L.; de la Rosa, Noel Upia; Vaughey, John T.; Brushett, Fikile R.

2017-08-01

The identification and development of conductive electrolytes with high concentrations of redox active species is key to realizing energy-dense nonaqueous flow batteries. Herein, we explore the use of ether solvents (1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (DEGDME), and tetraethylene glycol dimethyl ether (TEGDME)) as the basis for redox electrolytes containing a lithium ion supporting salt (LiBF4 or LiTFSI) and 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB) as an active material. An automated high-throughput platform is employed to screen various electrolyte compositions by measuring solution conductivity and solute solubility as a function of solvent and salt type, component concentration, and temperature. Subsequently, the electrochemical and transport properties of select redox electrolytes are characterized by cyclic voltammetry using glassy carbon disk electrodes and by linear sweep voltammetry using carbon fiber ultramicroelectrodes. In general, improvements in electrolyte conductivity and solute solubility are observed with ether-based formulations as compared to previously reported propylene carbonate (PC)-based formulations. In particular, the addition of DOL to a DME-based electrolyte increases the conductivity and decreases the temperature for solubilization at high LiTFSI and DBBB concentrations. The redox behavior of DBBB remains consistent across the range of concentrations tested while the diffusion coefficient scales with changes in solution viscosity.

HGF potentiates extracellular matrix-driven migration of human myoblasts: involvement of matrix metalloproteinases and MAPK/ERK pathway.

Science.gov (United States)

González, Mariela Natacha; de Mello, Wallace; Butler-Browne, Gillian S; Silva-Barbosa, Suse Dayse; Mouly, Vincent; Savino, Wilson; Riederer, Ingo

2017-10-10

The hepatocyte growth factor (HGF) is required for the activation of muscle progenitor cells called satellite cells (SC), plays a role in the migration of proliferating SC (myoblasts), and is present as a soluble factor during muscle regeneration, along with extracellular matrix (ECM) molecules. In this study, we aimed at determining whether HGF is able to interact with ECM proteins, particularly laminin 111 and fibronectin, and to modulate human myoblast migration. We evaluated the expression of the HGF-receptor c-Met, laminin, and fibronectin receptors by immunoblotting, flow cytometry, or immunofluorescence and used Transwell assays to analyze myoblast migration on laminin 111 and fibronectin in the absence or presence of HGF. Zymography was used to check whether HGF could modulate the production of matrix metalloproteinases by human myoblasts, and the activation of MAPK/ERK pathways was evaluated by immunoblotting. We demonstrated that human myoblasts express c-Met, together with laminin and fibronectin receptors. We observed that human laminin 111 and fibronectin have a chemotactic effect on myoblast migration, and this was synergistically increased when low doses of HGF were added. We detected an increase in MMP-2 activity in myoblasts treated with HGF. Conversely, MMP-2 inhibition decreased the HGF-associated stimulation of cell migration triggered by laminin or fibronectin. HGF treatment also induced in human myoblasts activation of MAPK/ERK pathways, whose specific inhibition decreased the HGF-associated stimulus of cell migration triggered by laminin 111 or fibronectin. We demonstrate that HGF induces ERK phosphorylation and MMP production, thus stimulating human myoblast migration on ECM molecules. Conceptually, these data state that the mechanisms involved in the migration of human myoblasts comprise both soluble and insoluble moieties. This should be taken into account to optimize the design of therapeutic cell transplantation strategies by improving

Metal and base free synthesis of primary amines via ipso amination of organoboronic acids mediated by [bis(trifluoroacetoxy)iodo]benzene (PIFA).

Science.gov (United States)

Chatterjee, Nachiketa; Goswami, Avijit

2015-08-07

A metal and base free synthesis of primary amines has been developed at ambient temperature through ipso amination of diversely functionalized organoboronic acids, employing a combination of [bis(trifluoroacetoxy)iodo]benzene (PIFA)-N-bromosuccinimide (NBS) and methoxyamine hydrochloride as the aminating reagent. The amines were primarily obtained as their trifluoroacetate salts which on subsequent aqueous alkaline work up provided the corresponding free amines. The combination of PIFA-NBS is found to be the mildest choice compared to the commonly used strong bases (e.g. n-BuLi, Cs2CO3) for activating the aminating agent. The reaction is expected to proceed via activation of the aminating reagent followed by B-N 1,2-aryl migration.

THE INFLUENCE OF BENZENE AS A TRACE REACTANT IN TITAN AEROSOL ANALOGS

Energy Technology Data Exchange (ETDEWEB)

Trainer, Melissa G. [Planetary Environments Laboratory, Code 699, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sebree, Joshua A. [NASA Postdoctoral Program Fellow, Code 699, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Heidi Yoon, Y.; Tolbert, Margaret A., E-mail: melissa.trainer@nasa.gov [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Box 216 UCB, Boulder, CO 80309 (United States)

2013-03-20

Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb in the stratosphere to ppm in the ionosphere. Sustained levels of benzene in the haze formation region could signify that it is an important reactant in the formation of Titan's organic aerosol. To date, there have not been laboratory investigations to assess the influence of benzene on aerosol properties. We report a laboratory study on the chemical composition of organic aerosol formed from C{sub 6}H{sub 6}/CH{sub 4}/N{sub 2} via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH{sub 4}/N{sub 2}. Our results show that even a trace amount of C{sub 6}H{sub 6} (10 ppm) has significant impact on the chemical composition and production rates of organic aerosol. There are several pathways by which photolyzed benzene may react to form larger molecules, both with and without the presence of CH{sub 4}, but many of these reaction mechanisms are only beginning to be explored for the conditions at Titan. Continued work investigating the influence of benzene in aerosol growth will advance understanding of this previously unstudied reaction system.

Method of preparation of tritiated benzene for measuring in hydrology low level tritium in a liquid scintillator; Methode de preparation de benzene tritie pour la mesure par scintillation en hydrologie de faibles teneurs en tritium

Energy Technology Data Exchange (ETDEWEB)

Pichat, L; Sharefkin, D; Herbert, M

1962-07-01

It is given a preliminary account of the preparation of tritiated benzene by decarboxylation of calcium mellitate (calcium benzene-hexa-carboxylate) at 500 deg C by an excess of tritiated barium or calcium hydroxide yield is 64-72 pour cent based on used calcium mellitate. Benzene obtained after a single distillation is free from seriously quenching impurities. It is obtained 10-15 g benzene per batch. It remains to determine the occurrence of an isotope effect during the reaction. Various improvements and modifications are still necessary to increase the size of the sample to be treated. (authors) [French] On donne une description preliminaire de la preparation de benzene tritie par decarboxylation du mellitate de calcium (benzenehexacarboxylate de calcium) a 500 deg C par la chaux ou la baryte tritiee en exces. Le rendement est de 64 a 72 % base sur le mellitate de calcium mis en oeuvre. Le benzene obtenu apres une simple distillation dans une colonne Vigreux ne contient pas d'impuretes pouvant, en scintillation, eteindre la fluorescence. En une operation, on peut obtenir 10-15 g de benzene. Il reste a determiner, si au cours de la reaction, il y a un effet isotopique. Diverses ameliorations et modifications sont encore indispensables en vue d'accroitre l'echelle sur laquelle l'operation peut etre conduite. (auteurs)

The role of octanol in the extraction of hydrochloric acid by trilaurylamine dissolved in benzene

International Nuclear Information System (INIS)

Muhammed, M.A.

1976-01-01

The extraction of hydrochloric acid by trilaurylamine (TLA) dissolved in benzene was studied in the presence and in absence of n-octanol. The extraction of HCl was found to be enhanced by the addition of octanol to the organic phase. In order to explain this effect by means of the law of mass action, the systems TLA-HCl-benzene and n-octanol-HCl-benzene as well as TLA-octanol-benzene were also studied. It was found that TLA reacts with octanol to form a complex TLAROH, while the octanol itself associates in benzene to form dimers and tetramers, although it does not extract HCl alone from the dilute solutions used in the present study. The enhancement of the extraction of HCl by TLA upon the addition of n-octanol could be described by the formation of the species TLA.ROH.HCl and its stability constant was determined. (author)

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries.

Science.gov (United States)

Chung, Eun-Kyo; Shin, Jung-Ah; Lee, Byung-Kyu; Kwon, Jiwoon; Lee, Naroo; Chung, Kwang-Jae; Lee, Jong-Han; Lee, In-Seop; Kang, Seong-Kyu; Jang, Jae-Kil

2010-09-01

The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

Airborne concentrations of benzene due to diesel locomotive exhaust in a roundhouse.

Science.gov (United States)

Madl, Amy K; Paustenbach, Dennis J

2002-12-13

Concentrations of airborne benzene due to diesel exhaust from a locomotive were measured during a worst-case exposure scenario in a roundhouse. To understand the upper bound human health risk due to benzene, an electromotive diesel and a General Electric four-cycle turbo locomotive were allowed to run for four 30-min intervals during an 8-h workshift in a roundhouse. Full-shift and 1-h airborne concentrations of benzene were measured in the breathing zone of surrogate locomotive repairmen over the 8-h workshift on 2 consecutive days. In addition, carbon monoxide was measured continuously; elemental carbon (surrogate for diesel exhaust) was sampled with full-shift area samples; and nitrogen dioxide/nitric oxide was sampled using full-shift and 15-min (nitrogen dioxide only) area samples. Peak concentrations of carbon monoxide ranged from 22.5 to 93 ppm. The average concentration of elemental carbon for each day of the roundhouse study was 0.0543 and 0.0552 microg/m(3 )for an 8-h workshift. These were considered "worst-case" conditions since the work environment was intolerably irritating to the eyes, nose, and throat. Short-term nitrogen dioxide concentrations ranged from 0.81 to 2.63 ppm during the diesel emission events with the doors closed. One-hour airborne benzene concentrations ranged from 0.001 to 0.015 ppm with 45% of the measurements below the detection limit of 0.002-0.004 ppm. Results indicated that the 8-h time-weighted average for benzene in the roundhouse was approximately 100-fold less than the current threshold limit value (TLV) of 0.5 ppm. These data are consistent with other studies, which have indicated that benzene concentrations due to diesel emissions, even in a confined environment, are quite low.

Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

Energy Technology Data Exchange (ETDEWEB)

Katoch, Neha, E-mail: nehakatoch2@gmail.com; Kapoor, Pooja; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

2016-05-23

We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G{sub 0} to 2G{sub 0} suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

Heavy metal migration through clay below a domestic waste site

Energy Technology Data Exchange (ETDEWEB)

Yanful, E K

1986-01-01

Migration of contaminants from a domestic waste landfill overlying a 30 m thick natural clay deposit is presented. Profiles for Na/sup +/, Mg/sup 2 +/, DOC and other soluble species indicate that, at 16 years, contaminants have migrated up to 130 cm from the waste. Profiles for conservative species suggest that Cl-, /sup 3/H, /sup 18/O and /sup 2/H fronts are ahead of those species such as Na/sup +/, K/sup +/ and DOC. In comparison, the heavy metals, Fe, Mn, Cu, Zn and Pb, have migrated only 10-20 cm. Batch equilibrium studies involving Fe/sup 2 +/, Cu/sup 2 +/, Zn/sup 2 +/ and Pb/sup 2 +/ result in classical adsorption-pH curves which show increasing adsorption at higher pH levels and vice versa. The presence of soil carbonates is shown to significantly increase the mass of Pb and Cu removed from domestic landfill leachate.

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Science.gov (United States)

2010-07-01

... accomplished by bag sampling as used for total hydrocarbons determination. This procedure is detailed in 40 CFR 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for benzene and 1,3-butadiene in bag samples for the baseline fuel are 4.0 ppm and 0.30 ppm respectively. At...

46 CFR Appendix B to Subpart C to... - Substance Technical Guidelines, Benzene

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Substance Technical Guidelines, Benzene B Appendix B to... Subpart C to Part 197—Substance Technical Guidelines, Benzene I. Physical and Chemical Data (a) Substance... temperature: 580 °C (1076 °F). (3) Flammable limits in air, % by volume: Lower: 1.3%, Upper: 7.5%. (4...

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

Science.gov (United States)

Jia, Long; Xu, Yong-Fu

2014-02-01

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

Changes in the nervous system state and peripheral blood parameters under benzene intoxication during an experiment

Directory of Open Access Journals (Sweden)

R.A. Orujov

2017-12-01

Full Text Available Benzene is a widely spread chemical health risk factor. Our research goal was to examine the nervous system state and the blood system state under benzene intoxication during an experiment. An acute experiment was performed on 45 white mice with 5-fold poisoning with benzene; a chronic one was performed on 72 rabbits being under inhalation exposure to benzene during 4 months, its concentrations increasing and fluctuating. We determined the following blood parameters: number of reticulocytes, eosinophils, basocytes, and erythrocytes; erythrocytes sedimentation rate; blood clotting period; blood clot retraction; plasma re-calcification period; plasma tolerance to heparin; prothrombin time; prothrombin index; fibrinogen concentration; blood fibrinolytic activity; acetylcholine and choline esterase contents. We also determined adrenalin, noradrenalin, dopamine, and dihydroxyphenylalanine contents in urine. Acute experiments results revealed that one-time exposure to benzene exerted a narcotic effect on the central nervous system which had an excitation phase and inhibition phase. Under a repeat exposure to benzene animals' drug intoxication was shorter. And here neutrophils / leucocytes gradient first increased to 139.5 % from its standards value and then when down under consequent intoxications. We detected relevant changes in morphological picture of animals' peripheral blood and their central and vegetative nervous system under chronic exposure to intermittent and increasing benzene concentrations. So, our research revealed that effects exerted by benzene in small concentrations led to apparent shifts in white blood and catecholamines (adrenalin, noradrenalin, dopamine, and dihydroxyphenylalanine. We also detected certain signs that cate-cholamines endogenous reserves (dihydroxyphenylalanine were depleted and, and also signs of eosinophils-basocytes disso-ciation; such prognostic signs were considered to be unfavorable as it was exactly at that

A preliminary assessment of gas diffusion and migration

Energy Technology Data Exchange (ETDEWEB)

Tanai, Kenji; Sato, Haruo [Waste Isolation Research Division, Tokai Works, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Murakami, Tomohiro [Toyo Engineering Corp., Tokyo (Japan); Inoue, Masahiro [Kyushu Univ., Fukuoka (Japan)

1999-11-01

In the anaerobic environment in the deep underground water, carbon-steel overpack corrodes and generates molecular hydrogen. It is conceivable that this hydrogen either dissolves into the porewater of the buffer and migrates through the buffer. If the rate of aqueous diffusion of hydrogen is too low compared to the rate of hydrogen generation, the concentration of hydrogen at the overpack surface will increase until a solubility limit is attained and a free hydrogen gas phase forms. It is possible that the pressure in this accumulating gas phase will increase, affecting the stability of the buffer or the surrounding rock mass. There is also a concern of possible effects on nuclide migration, as it is also conceivable that the flow of gas could push out radionuclide-bearing porewater in the buffer when it floes through the buffer. As such, experimental and analytical study must be carried out on such phenomenon to evaluate such potential phenomena. (1) Diffusion experiment of dissolved hydrogen. (2) Gas permeability. (3) Evaluation of diffusion of dissolved hydrogen and hydrogen gas migration. (J.P.N.)

In utero exposure to benzene increases embryonic c-Myb and Pim-1 protein levels in CD-1 mice

International Nuclear Information System (INIS)

Wan, Joanne; Winn, Louise M.

2008-01-01

Benzene is a known human leukemogen, but its role as an in utero leukemogen remains controversial. Epidemiological studies have correlated parental exposure to benzene with an increased incidence of childhood leukemias. We hypothesize that in utero exposure to benzene may cause leukemogenesis by affecting the embryonic c-Myb/Pim-1 signaling pathway and that this is mediated by oxidative stress. To investigate this hypothesis, pregnant CD-1 mice were treated with either 800 mg/kg of benzene or corn oil (i.p.) on days 10 and 11 of gestation and in some cases pretreated with 25 kU/kg of PEG-catalase. Phosphorylated and total embryonic c-Myb and Pim-1 protein levels were assessed using Western blotting and maternal and embryonic oxidative stress were assessed by measuring reduced to oxidized glutathione ratios. Our results show increased oxidative stress at 4 and 24 h after exposure, increased phosphorylated Pim-1 protein levels 4 h after benzene exposure, and increased Pim-1 levels at 24 and 48 h after benzene exposure. Embryonic c-Myb levels were elevated at 24 h after exposure. PEG-catalase pretreatment prevented benzene-mediated increases in embryonic c-Myb and Pim-1 protein levels, and benzene-induced oxidative stress. These results support a role for ROS in c-Myb and Pim-1 alterations after in utero benzene exposure

Investigating the effects of in utero benzene exposure on epigenetic modifications in maternal and fetal CD-1 mice

International Nuclear Information System (INIS)

Philbrook, Nicola A.; Winn, Louise M.

2015-01-01

Exposure to the ubiquitous environmental pollutant benzene is positively correlated with leukemia in adults and may be associated with childhood leukemia following in utero exposure. While numerous studies implicate oxidative stress and DNA damage as playing a role in benzene-mediated carcinogenicity, emerging evidence suggests that alterations in epigenetic regulations may be involved. The present study aimed to determine whether DNA methylation and/or various histone modifications were altered following in utero benzene exposure in CD-1 mice. Global DNA methylation and promoter-specific methylation of the tumor suppressor gene, p15, were assessed. Additionally, levels of acetylated histones H3, H4, and H3K56, as well as methylated histones H3K9 and H3K27 were assessed by Western blotting. A significant decrease in global DNA methylation of maternal bone marrow was observed following benzene exposure; however no effect on global DNA methylation was detected in fetal livers. Additionally, no effect of benzene exposure was observed on p15 promoter methylation or any measured histone modifications in both maternal bone marrow and fetal livers. These results suggest that the methodology used in the present study did not reveal alterations in DNA methylation and histone modifications following in utero exposure to benzene; however further experimentation investigating these modifications at the whole genome/epigenome level, as well as at later stages of benzene-induced carcinogenesis, are warranted. - Highlights: • Benzene exposure in pregnant mice decreased global DNA methylation in maternal bone marrow. • Benzene exposure in pregnant mice had no effect on global DNA methylation in fetal livers. • No effect of benzene exposure was observed on p15 promoter methylation. • No effect of benzene on measured histone modifications in both maternal bone marrow and fetal livers was observed.

Investigating the effects of in utero benzene exposure on epigenetic modifications in maternal and fetal CD-1 mice

Energy Technology Data Exchange (ETDEWEB)

Philbrook, Nicola A. [Department of Biomedical and Molecular Sciences, Graduate Program in Pharmacology and Toxicology, Queen' s University, Kingston, ON K7L3N6 (Canada); Winn, Louise M., E-mail: winnl@queensu.ca [Department of Biomedical and Molecular Sciences, Graduate Program in Pharmacology and Toxicology, Queen' s University, Kingston, ON K7L3N6 (Canada); School of Environmental Studies, Queen' s University, Kingston, ON K7L3N6 (Canada)

2015-11-15

Exposure to the ubiquitous environmental pollutant benzene is positively correlated with leukemia in adults and may be associated with childhood leukemia following in utero exposure. While numerous studies implicate oxidative stress and DNA damage as playing a role in benzene-mediated carcinogenicity, emerging evidence suggests that alterations in epigenetic regulations may be involved. The present study aimed to determine whether DNA methylation and/or various histone modifications were altered following in utero benzene exposure in CD-1 mice. Global DNA methylation and promoter-specific methylation of the tumor suppressor gene, p15, were assessed. Additionally, levels of acetylated histones H3, H4, and H3K56, as well as methylated histones H3K9 and H3K27 were assessed by Western blotting. A significant decrease in global DNA methylation of maternal bone marrow was observed following benzene exposure; however no effect on global DNA methylation was detected in fetal livers. Additionally, no effect of benzene exposure was observed on p15 promoter methylation or any measured histone modifications in both maternal bone marrow and fetal livers. These results suggest that the methodology used in the present study did not reveal alterations in DNA methylation and histone modifications following in utero exposure to benzene; however further experimentation investigating these modifications at the whole genome/epigenome level, as well as at later stages of benzene-induced carcinogenesis, are warranted. - Highlights: • Benzene exposure in pregnant mice decreased global DNA methylation in maternal bone marrow. • Benzene exposure in pregnant mice had no effect on global DNA methylation in fetal livers. • No effect of benzene exposure was observed on p15 promoter methylation. • No effect of benzene on measured histone modifications in both maternal bone marrow and fetal livers was observed.

Interpretation of Urinary and Blood Benzene biomarkers of Exposure for Non-Occupationally Exposed Individuals

Science.gov (United States)

Non-occupational exposure to benzene occurs primarily through inhalation ofair impacted by motor vehicle exhaust, fuel sources, and cigarette smoke. This study relates published measurements ofbenzene biomarkers to air exposure concentrations. Benzene has three reliable biomar...

Recommended sublimation pressure and enthalpy of benzene

Czech Academy of Sciences Publication Activity Database

Růžička, K.; Fulem, Michal; Červinka, C.

2014-01-01

Roč. 68, Jan (2014), s. 40-47 ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal - gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.679, year: 2014

Investigations and technical reviews on the reliability of prediction for migration behavior of radionuclides (H15)

International Nuclear Information System (INIS)

Tachikawa, Hirokazu

2004-02-01

The research plan of the validation on effects of colloids and organic materials drawn up by the Japan Nuclear Fuel Cycle Development Institute and its' research outcome were reviewed comprehensively by an expert committee established in the Nuclear Safety Research Association. Additionally, experimental investigations for the migration behavior of actinide elements and fission products in engineering barrier and natural barrier medias, and for solution chemistry of them were carried out and discussed by the committee, in order to enhance the reliability of prediction for migration behavior of radionuclides. The subjects investigated by the expert committee are as follows: (1) Research on solubility products of An(III) hydroxide. (2) Diffusion and electromigration behavior of plutonium in buffer material. (3) Analysis of the nuclide solubility in compacted bentonite. (4) Survey of the actual contamination by alpha emitters in steel materials. (author)

Organic-soluble lanthanide nuclear magnetic resonance shift reagents for sulfonium and isothiouronium salts

International Nuclear Information System (INIS)

Wenzel, T.J.; Zaia, J.

1987-01-01

Lanthanide complexes of the formula [Ln(fod) 4 ] - (FOD, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione) are effective organic-soluble nuclear magnetic resonance shift reagents for sulfonium and isothiouronium salts. The shift reagent is formed in solution from Ln(fod) 3 and Ag(fod) or K(fod). The selection of Ag(fod) or K(fod) in forming the shift reagent is dependent on the anion of the organic salt. Ag(fod) is more effective with halide salts, whereas K(fod) is preferred with tetrafluoroborate salts. Resolution of diastereotopic hydrogen atoms was observed in the shifted spectra of certain substrates. Enantiomeric resolution was obtained in the spectrum of sec-butylisothiouronium chloride with a chiral shift reagent. The reagents can be employed in solvents such as chloroform and benzene

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

Science.gov (United States)

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

2012-07-31

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

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

KAUST Repository

Turias, Francesc; Poater, Jordi; Chauvin, Remi; Poater, Albert

2015-01-01

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.

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

KAUST Repository

Turias, Francesc

2015-09-25

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.

Extraction of benzene and cyclohexane using [BMIM][N(CN)2] and their equilibrium modeling

Science.gov (United States)

Ismail, Marhaina; Bustam, M. Azmi; Man, Zakaria

2017-12-01

The separation of aromatic compound from aliphatic mixture is one of the essential industrial processes for an economically green process. In order to determine the separation efficiency of ionic liquid (IL) as a solvent in the separation, the ternary diagram of liquid-liquid extraction (LLE) 1-butyl-3-methylimidazolium dicyanamide [BMIM][N(CN)2] with benzene and cyclohexane was studied at T=298.15 K and atmospheric pressure. The solute distribution coefficient and solvent selectivity derived from the equilibrium data were used to evaluate if the selected ionic liquid can be considered as potential solvent for the separation of benzene from cyclohexane. The experimental tie line data was correlated using non-random two liquid model (NRTL) and Margules model. It was found that the solute distribution coefficient is (0.4430-0.0776) and selectivity of [BMIM][N(CN)2] for benzene is (53.6-13.9). The ternary diagram showed that the selected IL can perform the separation of benzene and cyclohexane as it has extractive capacity and selectivity. Therefore, [BMIM][N(CN)2] can be considered as a potential extracting solvent for the LLE of benzene and cyclohexane.

Methane from benzene in argon dielectric barrier discharge

International Nuclear Information System (INIS)

Das, Tomi Nath; Dey, G.R.

2013-01-01

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

Inelastic X-ray scattering on liquid benzene analyzed using a generalized Langevin equation

Science.gov (United States)

Yoshida, Koji; Fukuyama, Nami; Yamaguchi, Toshio; Hosokawa, Shinya; Uchiyama, Hiroshi; Tsutsui, Satoshi; Baron, Alfred Q. R.

2017-07-01

The dynamic structure factor, S(Q,ω), of liquid benzene was measured by meV-resolved inelastic X-ray scattering (IXS) and analyzed using a generalized Langevin model with a memory function including fast, μ-relaxation and slow, structural, α-relaxation. The model well reproduced the experimental S(Q,ω) of liquid benzene. The dispersion relation of the collective excitation energy yields the high-frequency sound velocity for liquid benzene as related to the α-relaxation. The ratio of the high-frequency to the adiabatic sound velocity is approximately 1.5, larger to that of carbon tetrachloride and smaller than those of methanol and water, reflecting the nature of intermolecular interactions.

Benzene Exposure Alters Expression of Enzymes Involved in Fatty Acid β-Oxidation in Male C3H/He Mice

Directory of Open Access Journals (Sweden)

Rongli Sun

2016-10-01

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.

Benzene and MTBE Sorption in Fine Grain Sediments

Science.gov (United States)

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

2003-12-01

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

The effect of dose, dose rate, route of administration, and species on tissue and blood levels of benzene metabolites

International Nuclear Information System (INIS)

Henderson, R.F.; Sabourin, P.J.; Bechtold, W.E.; Griffith, W.C.; Medinsky, M.A.; Birnbaum, L.S.; Lucier, G.W.

1989-01-01

Studies were completed in F344/N rats and B6C3F 1 mice to determine the effect of dose, dose rate, route of administration, and rodent species on formation of total and individual benzene metabolites. Oral doses of 50 mg/kg or higher saturated the capacity for benzene metabolism in both rats and mice, resulting in an increased proportion of the administered dose being exhaled as benzene. The saturating air concentration for benzene metabolism during 6-hr exposures was between 130 and 900 ppm. At the highest exposure concentration, rats exhaled approximately half of the internal dose retained at the end of the 6-hr exposure as benzene; mice exhaled only 15% as benzene. Mice were able to convert more of the inhaled benzene to metabolites than were rats. In addition, mice metabolized more of the benzene by pathways leading to the putative toxic metabolites, benzoquinone and muconaldehyde, than did rats. In both rats and mice, the effect of increasing dose, administered orally or by inhalation, was to increase the proportion of the total metabolites that were the products of detoxification pathways relative to the products of pathways leading to putative toxic metabolites. This indicates low-affinity, high-capacity pathways for detoxification and high-affinity, low-capacity pathways leading to putative toxic metabolites. If the results of rodent studied performed at high doses were used to assess the health risk at low-dose exposures to benzene, the toxicity of benzene would be underestimated

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

Science.gov (United States)

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

2013-01-01

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

Analysis of the processes defining radionuclide migration from deep geological repositories in porous medium

International Nuclear Information System (INIS)

Brazauskaite, A.; Poskas, P.

2004-01-01

Due to the danger of exposure arising from long-lived radionuclides to humans and environment, spent nuclear fuel (SNF) and high level waste (HLW) are not allowed to be disposed of in near surface repositories. There exists an international consensus that such high level and long-lived radioactive wastes are best disposed of in geological repositories using a system of engineered and natural barriers. At present, the geological repository of SNF and HLW has not been realized yet in any country but there is a lot of experience in the assessment of radionuclide migration from deep repositories, investigations of different processes related to the safety of a disposal system. The aim of this study was to analyze the processes related to the radionuclide migration from deep geological repositories in porous medium such as SNF matrix dissolution, release mechanism of radionuclides from SNF matrix, radionuclide solubility, sorption, diffusive, advective transport of radionuclides from the canister and through the engineered and natural barriers. It has been indicated that SNF matrix dissolution, radionuclide solubility and sorption are sensitive to ambient conditions prevailing in the repository. The approaches that could be used for modeling the radionuclide migration from deep repositories in porous medium are also presented. (author)

Cooperative research at JAERI on the consequences of the Chernobyl accident. 3. Distribution and migration characteristics of long-lived radionuclides in the environment around the damaged Chernobyl reactor

International Nuclear Information System (INIS)

Amano, Hikaru

2001-01-01

The purpose of this study was to elucidate the actual long-term migration characteristics of radionuclides released and accumulated on the earth surface environment after the reactor accident. The objective areas were mainly in 30 km distant areas from the reactor. The study concerned the distribution of radionuclides on the ground surface, their physical and chemical forms, their migration characteristics, their migration from the ground to aqueous system like river, their physical and chemical forms in that system, their migration into vegetables, and their re-floating and concentration in air. The study involved those methods such as a newly developed liquid scintillation counting of 241 Pu for assessing 241 Am accumulation and the alpha-track method for detection of hot particles. Findings were: Hot particles of small diameters around several microns were still present; Depth distribution of radionuclides was dependent on the soil sort; Chemical forms of 90 Sr, 137 Cs and transuranium elements were different; Depth distribution in the soil depended on chemical forms; Annual change of radionuclides was evident in air; Migration coefficients to vegetables were determined; High molecular weight organic colloid was important in the migration to water system; Amounts of 137 Cs and transuranium elements depended on those of suspended matters in the river water and >90% 90 Sr were in soluble forms; Apparent partition ratios (soluble/suspended) of radionuclides in the river and lake were determined; Soluble transuranium elements were bound to humus materials in the river. (K.H.)

Benzene leaks in sight; Benzeenlekken in het vizier

Energy Technology Data Exchange (ETDEWEB)

Okkerse, W.J.; Van Doorn, R.; Bison, H. [DCMR Milieudienst Rijnmond, Rotterdam (Netherlands)

2013-02-15

About five years ago, elevated concentrations of benzene were detected at air measuring stations of the DCMR Environmental Protection Agency in the Botlek area, the Netherlands. Extensive research of potential sources in industry followed. A wide range of advanced techniques were deployed. A smart combination of techniques has ultimately resulted in the identification and clean-up of the benzene sources. A bright future is anticipated for these techniques [Dutch] Ongeveer vijf jaar geleden werden rond het Botlekgebied verhoogde benzeenconcentraties geconstateerd op luchtmeetstations van de DCMR Milieudienst Rijnmond. Een uitgebreid onderzoek naar de potentiele bronnen in de industrie was het gevolg. Daarbij is een scala aan geavanceerde technieken ingezet. Toepassing van een slimme combinatie van technieken heeft er uiteindelijk toe geleid dat benzeenbronnen werden opgespoord en gesaneerd. Een grote toekomst wordt voorzien voor deze technieken.

Adsorption of trichloroethylene and benzene vapors onto hypercrosslinked polymeric resin

Energy Technology Data Exchange (ETDEWEB)

Liu Peng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Long Chao, E-mail: clong@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China); Li Qifen [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Qian Hongming [State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China); Li Aimin; Zhang Quanxing [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China)

2009-07-15

In this research, the adsorption equilibria of trichloroethylene (TCE) and benzene vapors onto hypercrosslinked polymeric resin (NDA201) were investigated by the column adsorption method in the temperature range from 303 to 333 K and pressures up to 8 kPa for TCE, 12 kPa for benzene. The Toth and Dubinin-Astakov (D-A) equations were tested to correlate experimental isotherms, and the experimental data were found to fit well by them. The good fits and characteristic curves of D-A equation provided evidence that a pore-filling phenomenon was involved during the adsorption of TCE and benzene onto NDA-201. Moreover, thermodynamic properties such as the Henry's constant and the isosteric enthalpy of adsorption were calculated. The isosteric enthalpy curves varied with the surface loading for each adsorbate, indicating that the hypercrosslinked polymeric resin has an energetically heterogeneous surface. In addition, a simple mathematic model developed by Yoon and Nelson was applied to investigate the breakthrough behavior on a hypercrosslinked polymeric resin column at 303 K and the calculated breakthrough curves were in high agreement with corresponding experimental data.

Adsorption of trichloroethylene and benzene vapors onto hypercrosslinked polymeric resin.

Science.gov (United States)

Liu, Peng; Long, Chao; Li, Qifen; Qian, Hongming; Li, Aimin; Zhang, Quanxing

2009-07-15

In this research, the adsorption equilibria of trichloroethylene (TCE) and benzene vapors onto hypercrosslinked polymeric resin (NDA201) were investigated by the column adsorption method in the temperature range from 303 to 333 K and pressures up to 8 kPa for TCE, 12 kPa for benzene. The Toth and Dubinin-Astakov (D-A) equations were tested to correlate experimental isotherms, and the experimental data were found to fit well by them. The good fits and characteristic curves of D-A equation provided evidence that a pore-filling phenomenon was involved during the adsorption of TCE and benzene onto NDA-201. Moreover, thermodynamic properties such as the Henry's constant and the isosteric enthalpy of adsorption were calculated. The isosteric enthalpy curves varied with the surface loading for each adsorbate, indicating that the hypercrosslinked polymeric resin has an energetically heterogeneous surface. In addition, a simple mathematic model developed by Yoon and Nelson was applied to investigate the breakthrough behavior on a hypercrosslinked polymeric resin column at 303 K and the calculated breakthrough curves were in high agreement with corresponding experimental data.

Decomposition of multilayer benzene and n-hexane films on vanadium.

Science.gov (United States)

Souda, Ryutaro

2015-09-21

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.

Adsorption of trichloroethylene and benzene vapors onto hypercrosslinked polymeric resin

International Nuclear Information System (INIS)

Liu Peng; Long Chao; Li Qifen; Qian Hongming; Li Aimin; Zhang Quanxing

2009-01-01

In this research, the adsorption equilibria of trichloroethylene (TCE) and benzene vapors onto hypercrosslinked polymeric resin (NDA201) were investigated by the column adsorption method in the temperature range from 303 to 333 K and pressures up to 8 kPa for TCE, 12 kPa for benzene. The Toth and Dubinin-Astakov (D-A) equations were tested to correlate experimental isotherms, and the experimental data were found to fit well by them. The good fits and characteristic curves of D-A equation provided evidence that a pore-filling phenomenon was involved during the adsorption of TCE and benzene onto NDA-201. Moreover, thermodynamic properties such as the Henry's constant and the isosteric enthalpy of adsorption were calculated. The isosteric enthalpy curves varied with the surface loading for each adsorbate, indicating that the hypercrosslinked polymeric resin has an energetically heterogeneous surface. In addition, a simple mathematic model developed by Yoon and Nelson was applied to investigate the breakthrough behavior on a hypercrosslinked polymeric resin column at 303 K and the calculated breakthrough curves were in high agreement with corresponding experimental data.

The oxidative conversion of toluene to benzene

NARCIS (Netherlands)

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

1971-01-01

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

Bis(2-formylphenyl benzene-1,2-dicarboxylate

Directory of Open Access Journals (Sweden)

Shaaban K. Mohamed

2018-02-01

Full Text Available The asymmetric unit of the title compound, C22H14O6, consists of two independent molecules differing in the orientations of the ester groups. In one molecule, the two terminal benzene rings are inclined to the central benzene ring by 4.99 (13 and 77.46 (13°, while in the other the corresponding angles are 11.03 (13 and 88.09 (12°. In the crystal, molecules are connected into a ribbon structure running along [101] via C—H...O and C—H...π interactions. Adjacent ribbons are further linked by additional C—H...O and C—H...π interactions. The crystal studied was a non-merohedral twin [twin law (0.986 − 0.073 − 0.008, 0.323 1.036 0.148, −0.121 − 0.102 0.942], the ratio of components being 0.937 (4:0.063 (4.

Triptycene-Based Microporous Cyanate Resins for Adsorption/Separations of Benzene/Cyclohexane and Carbon Dioxide Gas.

Science.gov (United States)

Deng, Gaoyang; Wang, Zhonggang

2017-11-29

Triptycene-based cyanate monomers 2,6,14-tricyanatotriptycene (TPC) and 2,6,14-tris(4-cyanatophenyl)triptycene (TPPC) that contain different numbers of benzene rings per molecule were synthesized, from which two microporous cyanate resins PCN-TPC and PCN-TPPC were prepared. Of interest is the observation that the two polymers have very similar porosity parameters, but PCN-TPPC uptakes considerably higher benzene (77.8 wt %) than PCN-TPC (17.6 wt %) at room temperature since the higher concentration of phenyl groups in PCN-TPPC enhances the π-π interaction with benzene molecules. Besides, the adsorption capacity of benzene in PCN-TPPC is dramatically 7 times as high as that of cyclohexane. Contrary to the adsorption of organic vapors, at 273 K and 1.0 bar, PCN-TPC with more heteroatoms in the network skeleton displays larger uptake of CO 2 and higher CO 2 /N 2 selectivity (16.4 wt %, 60) than those of PCN-TPPC (14.0 wt %, 39). The excellent and unique adsorption properties exhibit potential applications in the purification of small molecular organic hydrocarbons, e.g., separation of benzene from benzene/cyclohexane mixture as well as CO 2 capture from flue gas. Moreover, the results are helpful for deeply understanding the effect of porous and chemical structures on the adsorption properties of organic hydrocarbons and CO 2 gas.

Interactions of Na+, K+, Mg2+, and Ca 2+ with benzene self-assembled monolayers

DEFF Research Database (Denmark)

Pedersen, Morten Rimmen; Matthiesen, Jesper; Bovet, Nicolas Emile

2014-01-01

that are most common in the natural world, namely, Na+, K+, Mg 2+, and Ca2+. Specifically, we investigated how these ions affect the interactions between surfaces covered by self-Assembled monolayers (SAMs) terminated with benzene molecules. We used a flat oxidized silicon substrate and an atomic force...... from X-ray photoelectron spectroscopy (XPS) allowed us to conclude that K+ binds in the benzene layers, creating a positive surface charge on the benzene-covered surfaces, thus leading to lower adhesion in KCl solutions than in pure water. Evidence suggested that Ca2+ does not bind to the surfaces...... measurements. The results of our studies clearly show that even a nonpolar, hydrophobic molecule, such as benzene, has a role to play in the behavior of aqueous solutions and that it interacts differently depending on which ions are present. Even ions from the same column in the periodic table behave...

Kinetics of granulocytic and erythroid progenitor cells are affected differently by short-term, low-level benzene exposure

Energy Technology Data Exchange (ETDEWEB)

Dempster, A.M.; Snyder, C.A. (New York Univ. Medical Center, NY (United States). Inst. of Environmental Medicine)

1991-09-01

Mice were exposed to either air or 10 ppm benzene for 6 h/d X 5 d. Immediately after the last exposure, mice were injected, i.v., with either saline or hydroxyurea (HU). The dose of HU was sufficient to kill hematopoietic cells in or near S-phase of the cell cycle and sufficient to synchronize the surviving populations of hematopoietic cells. Three days after benzene exposure, CFU-E numbers had declined to 50% of control values while CFU-GM numbers were equal to control values at this time. The benzene exposures were sufficient to double the percentage of CFU-E in S-phase but produced no such increase among CFU-Gm. During 3 days of recovery from benzene exposure and HU treatment, the CFU-E population expanded 30-fold while the CFU-GM population expanded less than 3-fold. Following benzene exposure and HU treatment, both progenitor cells produced elevated numbers of their respective progeny. When CFU-E from benzene-exposed mice were cultured with varying concentrations of erythropoietin (EPO), the response at maximal EPO concentration was 66% of the response by control CFU-E. This strongly suggests that the CFU-E populations from benzene-exposed mice had been depleted of cells in or near S-phase. The results indicate that CFU-GM respond to low-level benzene exposure by increasing their rate of differentiation but not their rate of proliferation, while CFU-E respond by increasing both their rates of differentiation and proliferation. We speculate that it is the increase in CFU-E proliferation that renders these cells more susceptible to benzene than their granulocytic counterparts, especially those CFU-E at or near the S-phase of the cell cycle. (orig.).

Simultaneous exposure to ethyl benzene and noise : synergistic effects on outer hair cells

NARCIS (Netherlands)

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

2001-01-01

The effects on hearing of simultaneous exposure to the ototoxic organic solvent ethyl benzene and broad-band noise were evaluated in rats. The effects of three ethyl benzene concentrations (0, 300 or 400 ppm) and three noise levels (95 or 105 dBlin SPL or background noise at 65 dBlin SPL) and all

Personal exposure to benzene and 1,3-butadiene during petroleum refinery turnarounds and work in the oil harbour.

Science.gov (United States)

Akerstrom, M; Almerud, P; Andersson, E M; Strandberg, B; Sallsten, G

2016-11-01

Petroleum refinery workers' exposure to the carcinogens benzene and 1,3-butadiene has decreased during normal operations. However, certain occupational groups or events at the refineries still involve a risk of higher exposures. The aim of this study was to examine the personal exposure to benzene and 1,3-butadiene at refinery turnarounds and during work in the oil harbour. Personal exposure measurements of benzene and 1,3-butadiene were taken during work shifts, with a priori assumed higher benzene exposure, using PerkinElmer diffusive samplers filled with Carbopack X. Mean exposure levels were calculated, and repeated exposure measurements, when available, were assessed using mixed effect models. Group and individual compliance with the Swedish occupational exposure limit (OEL) was tested for the different exposure groups. Mean benzene exposure levels for refinery workers during the three measured turnarounds were 150, 610 and 960 µg/m 3 , and mean exposures for oil harbour workers and sewage tanker drivers were 310 and 360 µg/m 3 , respectively. Higher exposures were associated with handling benzene-rich products. Most occupational groups did not comply with the Swedish OEL for benzene nor did the individuals within the groups. The exposure to 1,3-butadiene was very low, between Work within the petroleum refinery industry, with potential exposure to open product streams containing higher fractions of benzene, pose a risk of personal benzene exposures exceeding the OEL. Refinery workers performing these work tasks frequently, such as contractors, sewage tanker drivers and oil harbour workers, need to be identified and protected.

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

Science.gov (United States)

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

2016-01-01

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

On the mechanistic differences of benzene-induced leukemogenesis between wild type and p53 knockout mice

International Nuclear Information System (INIS)

Hirabayashi, Yoko; Yoon, Byung-Il; Kawasaki, Yasushi; Li, Guang-Xun; Kanno, Jun; Inoue, Tohru

2003-01-01

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)

Resolving uncertainty in the spatial relationships between passive benzene exposure and risk of non-Hodgkin lymphoma.

Science.gov (United States)

Switchenko, Jeffrey M; Bulka, Catherine; Ward, Kevin; Koff, Jean L; Bayakly, A Rana; Ryan, P Barry; Waller, Lance A; Flowers, Christopher R

2016-04-01

Benzene is a known occupational carcinogen associated with increased risk of hematologic cancers, but the relationships between quantity of passive benzene exposure through residential proximity to toxic release sites, duration of exposure, lag time from exposure to cancer development, and lymphoma risk remain unclear. We collected release data through the Environmental Protection Agency's Toxics Release Inventory (TRI) from 1989 to 2003, which included location of benzene release sites, years when release occurred, and amount of release. We also collected data on incident cases of non-Hodgkin lymphoma (NHL) from the Georgia Comprehensive Cancer Registry (GCCR) for the years 1999-2008. We constructed distance-decay surrogate exposure metrics and Poisson and negative binomial regression models of NHL incidence to quantify associations between passive exposure to benzene and NHL risk and examined the impact of amount, duration of exposure, and lag time on cancer development. Akaike's information criteria (AIC) were used to determine the scaling factors for benzene dispersion and exposure periods that best predicted NHL risk. Using a range of scaling factors and exposure periods, we found that increased levels of passive benzene exposure were associated with higher risk of NHL. The best fitting model, with a scaling factor of 4 kilometers (km) and exposure period of 1989-1993, showed that higher exposure levels were associated with increased NHL risk (Level 4 (1.1-160kilograms (kg)) vs. Level 1: risk ratio 1.56 [1.44-1.68], Level 5 (>160kg) vs. Level 1: 1.60 [1.48-1.74]). Higher levels of passive benzene exposure are associated with increased NHL risk across various lag periods. Additional epidemiological studies are needed to refine these models and better quantify the expected total passive benzene exposure in areas surrounding release sites. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of electrode geometry on the performance of dielectric barrier/packed-bed discharge plasmas in benzene degradation

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: • Benzene was successfully degraded by dielectric barrier/packed-bed discharge plasmas. • Different electrode geometry has distinct effect on plasmas oxidation performance. • Benzene degradation and energy performance were enhanced when using the coil electrode. • The reaction products were well determined by online FTIR analysis. -- Abstract: In this study, the effects of electrode geometry on benzene degradation in a dielectric barrier/packed-bed discharge plasma reactor with different electrodes were systematically investigated. Three electrodes were employed in the experiments, these were coil, bolt, and rod geometries. The reactor using the coil electrode showed better performance in reducing the dielectric loss in the barrier compared to that using the bolt or rod electrodes. In the case of the coil electrode, both the benzene degradation efficiency and energy yield were higher than those for the other electrodes, which can be attributed to the increased role of surface mediated reactions. Irrespective of the electrode geometry, the packed-bed discharge plasma was superior to the dielectric barrier discharge plasma in benzene degradation at any specific applied voltage. The main gaseous products of benzene degradation were CO, CO 2 , H 2 O, and formic acid. Discharge products such as O 3 , N 2 O, N 2 O 5 , and HNO 3 were also detected in the outlet gas. Moreover, the presence of benzene inhibited the formation of ozone because of the competing reaction of oxygen atoms with benzene. This study is expected to offer an optimized approach combining dielectric barrier discharge and packed-bed discharge to improve the degradation of gaseous pollutants

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons.

Science.gov (United States)

Chiang, Hung-Lung; Lin, Kuo-Hsiung; Chen, Chih-Yu; Choa, Ching-Guan; Hwu, Ching-Shyung; Lai, Nina

2006-05-01

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.

Inhibition of Ps Formation in Benzene and Cyclohexane by CH3CI and CH3Br

DEFF Research Database (Denmark)

Wikander, G.; Mogensen, O. E.; Pedersen, Niels Jørgen

1983-01-01

Positron-annihilation lifetime spectra have been measured for mixtures of CH3Cl and CH3Br in cyclohexane and of CH3Cl in benzene. The ortho-positronium (Ps) yield decreased monotonically from 38% and 43% in cyclohexane and benzene respectively to 11% in pure CH3Cl and 6% in pure CH3Br. The strength......− anions to form Ps. while it forms a bound state with the halides. X−. CH3Cl was a roughly three times weaker Ps inhibitor in benzene than in cyclohexane, which shows that CH3Cl− does not dechlorinate in times comparable to or shorter than 400–500 ps in benzene. An improved model for the explanation of Ps...

Separation of benzene from mixtures with water, methanol, ethanol, and acetone: highlighting hydrogen bonding and molecular clustering influences in CuBTC

NARCIS (Netherlands)

Gutiérrez-Sevillano, J.J.; Calero, S.; Krishna, R.

2015-01-01

Configurational-bias Monte Carlo (CBMC) simulations are used to establish the potential of CuBTC for separation of water/benzene, methanol/benzene, ethanol/benzene, and acetone/benzene mixtures. For operations under pore saturation conditions, the separations are in favor of molecules that partner

Method of preparation of tritiated benzene for measuring in hydrology low level tritium in a liquid scintillator

International Nuclear Information System (INIS)

Pichat, L.; Sharefkin, D.; Herbert, M.

1962-01-01

It is given a preliminary account of the preparation of tritiated benzene by decarboxylation of calcium mellitate (calcium benzene-hexa-carboxylate) at 500 deg C by an excess of tritiated barium or calcium hydroxide yield is 64-72 pour cent based on used calcium mellitate. Benzene obtained after a single distillation is free from seriously quenching impurities. It is obtained 10-15 g benzene per batch. It remains to determine the occurrence of an isotope effect during the reaction. Various improvements and modifications are still necessary to increase the size of the sample to be treated. (authors) [fr

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Science.gov (United States)

2010-07-01

... concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported... percent benzene). i = Individual batch of gasoline produced at the refinery or imported during the applicable averaging period. n = Total number of batches of gasoline produced at the refinery or imported...

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

2003-01-01

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...... oxidation product, a thiophene sulphoxide dimer, represented 78+/-12% of the transformed thiophene, while the second most important product, also a thiophene sulphoxide dimer, represented 20+/-2% of the converted thiophene. (C) 2003 Elsevier Science Ltd. All rights reserved....

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

International Nuclear Information System (INIS)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O_3 catalytic oxidation. • O_3 byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O_3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O_3 catalytic decomposition and utilization. Benzene and O_3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O_3 was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Energy Technology Data Exchange (ETDEWEB)

Huang, Haibao, E-mail: seabao8@gmail.com [School of Environmental Science and Engineering, Sun Yat-Sen University (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University) (China); Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo [School of Environmental Science and Engineering, Sun Yat-Sen University (China)

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O{sub 3} catalytic oxidation. • O{sub 3} byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O{sub 3}, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O{sub 3} catalytic decomposition and utilization. Benzene and O{sub 3} removal efficiency reached as high as 97% and 100% after 360 min, respectively. O{sub 3} was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

Ion induced polymerization in benzene frozen films

Energy Technology Data Exchange (ETDEWEB)

Calcagno, G [Catania Univ. (Italy). Ist. di Fisica; Strazzulla, G [Catania Univ. (Italy). Osservatorio Astrofisico; Fichera, M; Foti, G [Catania Univ. (Italy). Ist. di Radiologia

1983-07-01

The cross section of the polymerization process induced by energetic protons colliding with frozen benzene layers has been measured. The results have been described by a simple theory and they show that the process is a volume one occurring along the ion track and interesting all of the crossed layers.

Draft Benzene Case Study Review - Second Prospective Report Study Science Advisory Board Review, March 2008

Science.gov (United States)

EPA developed a methodology for estimating the health benefits of benzene reductions and has applied it in a metropolitan-scale case study of the benefits of CAA controls on benzene emissions to accompany the main 812 analysis.

Benzene Case Study Final Report - Second Prospective Report Study Science Advisory Board Review, July 2009

Science.gov (United States)

EPA developed a methodology for estimating the health benefits of benzene reductions and has applied it in a metropolitan-scale case study of the benefits of CAA controls on benzene emissions to accompany the main 812 analysis.

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

KAUST Repository

Goumri-Said, Souraya

2013-01-03

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.

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

KAUST Repository

Goumri-Said, Souraya; Benali Kanoun, Mohammed; Manchon, Aurelien; Schwingenschlö gl, Udo

2013-01-01

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.

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

Directory of Open Access Journals (Sweden)

Kheirbek Iyad

2012-07-01

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

Characterization of vanadium-doped mesoporous titania and its adsorption of gaseous benzene

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Phan, Thuy-Duong; Song, Myoung Bock; Yun, Hyunran; Kim, Eui Jung; Oh, Eun-Suok [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@mail.ulsan.ac.kr [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of)

2011-01-01

A series of vanadium-doped mesoporous titania with different metal contents was synthesized in the study via a sol-gel process with the assistance of a dodecylamine surfactant. The existence of vanadium ions not only suppressed crystallization and sintering but also enhanced the porosity of the mesoporous TiO{sub 2}. Varying the vanadium concentration led to significant changes in the chemical oxidation state of each component. The presence of metal dopants significantly improved the removal efficiency of benzene and the doping the titania with 5 mol% vanadium removed the most benzene, regardless of the adsorption temperature. The adsorption behavior was elucidated by the specific surface area, the interactions between surface hydroxyl groups and the {pi}-electrons of benzene, and the formation of {sigma}-bonding and d-{pi}* back-donation between the adsorbent and organic compounds.

Meta-analysis of benzene exposure and non-Hodgkin lymphoma: biases could mask an important association

Science.gov (United States)

Steinmaus, C; Smith, A H; Jones, R M; Smith, M T

2015-01-01

Objectives Benzene is a widely recognised cause of leukaemia but its association with non-Hodgkin’s lymphoma (NHL) is less well established. The goal of this project is to review the current published literature on this association. Methods We performed a meta-analysis of cohort and case-control studies of benzene exposure and NHL and a meta-analysis of NHL and refinery work, a potential source of benzene exposure. Results In 22 studies of benzene exposure, the summary relative risk for NHL was 1.22 (95% CI 1.02 to 1.47; one-sided p value = 0.01). When studies that likely included unexposed subjects in the “exposed” group were excluded, the summary relative risk increased to 1.49 (95% CI 1.12 to 1.97, n = 13), and when studies based solely on self-reported work history were excluded, the relative risk rose to 2.12 (95% CI 1.11 to 4.02, n = 6). In refinery workers, the summary relative risk for NHL in all 21 studies was 1.21 (95% CI 1.00 to 1.46; p = 0.02). When adjusted for the healthy worker effect, this relative risk estimate increased to 1.42 (95% CI 1.19 to 1.69). Conclusions The finding of elevated relative risks in studies of both benzene exposure and refinery work provides further evidence that benzene exposure causes NHL. In addition, the finding of increased relative risks after removing studies that included unexposed or lesser exposed workers in “exposed” cohorts, and increased relative risk estimates after adjusting for the healthy worker effect, suggest that effects of benzene on NHL might be missed in occupational studies if these biases are not accounted for. PMID:18417556

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

NARCIS (Netherlands)

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

2002-01-01

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

Effect of phenobarbital pretreatment on benzene biotransformation in the rat. Pt. 2. 9. 000 g supernatant and isolated perfused liver versus living rat

Energy Technology Data Exchange (ETDEWEB)

Gut, I.; Hatle, K.; Zizkova, L.

1981-03-01

Factors responsible for different quantitative effect of phenobarbital (PB) pretreatment on benzene metabolism to phenol in vivo and in vitro were studied in male Wistar rats. A more than 4-fold increase of benzene metabolism was observed with 9,000 g supernatant of liver homogenate, 2.8- to 4-fold increase with isolated perfused liver; phenol formation in vivo after oral benzene was increased by PB 2-fold, but only shortly following benzene administration and the enhancement rapidly diminished to 1.15-fold increase in the total excreted phenol. Benzene concentrations in 9,000 g supernatant incubations were 2 mM, those with isolated perfused livers were up to 4 mM, but those in blood in vivo were below 0.3 mM; the effect of PB induction in vivo disappeared along with decreasing benzene and increasing phenol blood concentrations which surpassed benzene 2-3 h after oral benzene administration. The effect of benzene concentration on the manifestation of PB induction is also supported by almost a 2-fold increased phenol formation in PB rats over controls in vivo after repeated administration of benzene. The elimination of radioactive metabolites of orally administered benzene-/sup 14/C, in urine was markedly inhibited by intraperitoneal administration of phenol, but not by pyrocatechol, resorcinol or hydroquinol suggesting that phenol might inhibit benzene metabolism in vivo especially when its concentration exceeds that of benzene.

Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity

Directory of Open Access Journals (Sweden)

Valquíria Campos

2015-04-01

Full Text Available The purpose of this work was to structurally modify clays in order to incorporate water-insoluble molecules, such as petroleum hydrocarbons. The potential for ion exchange of quaternary ammonium salts was studied, which revealed their ability to interact with anions on the cationic surface, for environmental applications of the material. Ionenes, also known as polycations, have many potential uses in environmental applications. In this work, cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene, were prepared for incorporation into clay to form bentonite-ionene complexes. The intercalation of bentonite with ionene polymers resulted in an increase in the basal spacing of 3,6-dodecylionene from 1.5-3.5 nm. The higher d001 spacing of 3,6-dodecylionene samples than that of 3,6-ionene samples may be attributed to their longer tail length. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174.85 kJ mol–1 is thermally more stable than 3,6 ionene (E = 115.52 kJ mol–1 complexes. The adsorption of benzene by 3,6-ionene and 3,6-dodecylionene was also investigated. The increase in benzene concentrations resulted in increased benzene adsorption by the sorbents tested in this work. The sorption capacity of benzene on ionene-modified bentonite was in the order of 3,6-dodecylionene > 3,6-ionene.

Managing Exposure to Benzene and Total Petroleum Hydrocarbons at Two Oil Refineries 1977-2014.

Science.gov (United States)

Tuomi, Tapani; Veijalainen, Henna; Santonen, Tiina

2018-01-24

Air concentrations of and inhalation exposure to total petroleum hydrocarbons (TPH) and benzene was monitored separately at two oil refineries from 1977 to 2014. Prevention policies and control measures that may explain changes were surveyed. The aim was to evaluate how the application of of Occupational Health and Safety Assessment Series OHSAS 18001.04 principles as well as Environmental protection Agency EPA and European Oil Company Organisation for Environment, Health and Safety CONCAWE practices have influenced air concentrations. Benzene air concentrations declined in 11 of 17 units, six of which were associated with declining exposures. Benzene air concentrations declined across all units on average by 46%. This amounts to an average yearly decline of 1.7%. TPH air concentrations declined in 10 of 17 units, seven of which were associated with declining exposures. The average decline in TPH air concentrations was 49%, corresponding to 1.3% per year. As a result, average working day exposure in 10 of 17 units have declined significantly and today, benzene and TPH exposure in most units are well below 10% of the current Occupational Exposure Limit (OEL 8h :s). A decline in air concentrations have coincided with consistent implementation of control measures. Such measures include on-line monitoring of leaks; benzene recovery; floating container roofs; improved valves and seals; hermetic pumps; recovery of loading gases and instalment of torches in terminals; cutback in coke combustion; a new production line spanning directly from the dock to aromatics production; and recovery of loading gases in the doc. Other tools in exposure management include personal leak monitors, on-line measurements, monitoring campaigns, risk assessment, and availability and user training of protective equipment. However, improvements are still needed. Hydrocarbon or benzene air concentrations have not declined in 8 of 17 units, in some of which concentrations exceed 10% of the relevant

Measurement of DNA repair deficiency in workers exposed to benzene

International Nuclear Information System (INIS)

Hallberg, L.M.; Au, W.W.; El Zein, R.; Grossman, L.

1996-01-01

We hypothesize that chronic exposure to environmental toxicants can induce genetic damage causing DNA repair deficiencies and leading to the postulated mutator phenotype of carcinogenesis. To test our hypothesis, a host cell reactivation (HCR) assay was used in which pCMVcat plasmids were damaged with UV light (175, 350 J/m 2 UV light), inactivating the chloramphenicol acetyltransferase reporter gene, and then transfected into lymphocytes. Transfected lymphocytes were therefore challenged to repair the damaged plasmids, reactivating the reporter gene. Xeroderma pigmentosum (XP) and Gaucher cell lines were used as positive and negative controls for the HCR assay. The Gaucher cell line repaired normally but XP cell lines demonstrated lower repair activity. Additionally, the repair activity of the XP heterozygous cell line showed intermediate repair compared to the homozygous XP and Gaucher cells. We used HCR to measure the effects of benzene exposure on 12 exposed and 8 nonexposed workers from a local benzene plant. Plasmids 175 J/m 2 and 350 J/m 2 were repaired with a mean frequency of 66% and 58%, respectively, in control workers compared to 71% and 62% in exposed workers. Conversely, more of the exposed workers were grouped into the reduced repair category than controls. These differences in repair capacity between exposed and control workers were, however, not statistically significant. The lack of significant differences between the exposed and control groups may be due to extremely low exposure to benzene (<0.3 ppm), small population size, or a lack of benzene genotoxicity at these concentrations. These results are consistent with a parallel hprt gene mutation assay. 26 refs., 4 figs., 2 tabs

Studies on migration behavior of radionuclides under reducing conditions in JNC

International Nuclear Information System (INIS)

Kitamura, A.; Sato, H.

2002-01-01

Japan Nuclear Cycle Development Institute (JNC) has performed extensive researches and developments to investigate the geochemistry and radionuclide migration in buffer materials and geosphere. Experimental and modeling studies have been carried out related to the geological disposal of high-level radioactive waste (HLW) as a link in the chair of a follow-up of the second progress report, which has explained in the technical feasibility of HLW geological disposal in Japan. In this paper, three experimental studies on solubility, sorption and diffusion of radionuclides under reducing conditions for assuring the reliability and for improving the quality of the databases are introduced. Solubility and sorption behavior of neptunium (Np) have been studied under reducing conditions in carbonate media. For the solubility study, thermodynamic equilibrium constants of carbonatohydroxo complexes of Np(IV) have been determined from a solubility measurement in alkaline solutions. For the sorption study, distribution coefficient (K d ) of Np onto smectite has been determined in weak alkaline solutions under reducing conditions in carbonate media. For the diffusion study, apparent diffusivity (D a ) of selenium (Se) in compacted bentonite have been determined under reducing conditions as a function of silica sand content and temperature

An analysis of workplace exposures to benzene over four decades at a petrochemical processing and manufacturing facility (1962-1999).

Science.gov (United States)

Sahmel, J; Devlin, K; Burns, A; Ferracini, T; Ground, M; Paustenbach, D

2013-01-01

Benzene, a known carcinogen, can be generated as a by-product during the use of petroleum-based raw materials in chemical manufacturing. The aim of this study was to analyze a large data set of benzene air concentration measurements collected over nearly 40 years during routine employee exposure monitoring at a petrochemical manufacturing facility. The facility used ethane, propane, and natural gas as raw materials in the production of common commercial materials such as polyethylene, polypropylene, waxes, adhesives, alcohols, and aldehydes. In total, 3607 benzene air samples were collected at the facility from 1962 to 1999. Of these, in total 2359 long-term (>1 h) personal exposure samples for benzene were collected during routine operations at the facility between 1974 and 1999. These samples were analyzed by division, department, and job title to establish employee benzene exposures in different areas of the facility over time. Sampling data were also analyzed by key events over time, including changes in the occupational exposure limits (OELs) for benzene and key equipment process changes at the facility. Although mean benzene concentrations varied according to operation, in nearly all cases measured benzene quantities were below the OEL in place at the time for benzene (10 ppm for 1974-1986 and 1 ppm for 1987-1999). Decreases in mean benzene air concentrations were also found when data were evaluated according to 7- to 10-yr periods following key equipment process changes. Further, an evaluation of mortality rates for a retrospective employee cohort (n = 3938) demonstrated that the average personal benzene exposures at this facility (0.89 ppm for the period 1974-1986 and 0.125 ppm for the period 1987-1999) did not result in increased standardized mortality ratio (SMRs) for diseases or malignancies of the lymphatic system. The robust nature of this data set provides comprehensive exposure information that may be useful for assessing human benzene exposures at

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

International Nuclear Information System (INIS)

Yu, Hang; Ming, Hai; Zhang, Hengchao; Li, Haitao; Pan, Keming; Liu, Yang; Wang, Fang; Gong, Jingjing; Kang, Zhenhui

2012-01-01

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: ► The composites that Au nanoparticles supported on ZnO nanowires were synthesized. ► Au/ZnO composites were firstly used as effective photocatalysts for benzene degradation. ► Two operating mechanisms were proposed depending on excitation wavelength.

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

DEFF Research Database (Denmark)

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

2010-01-01

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....

Integral migration and source term experiments on cement and bitumen waste forms

International Nuclear Information System (INIS)

Ewart, F.T.; Howse, R.M.; Sharpe, B.M.; Smith, A.J.; Thomason, H.P.; Williams, S.J.; Young, M.

1986-01-01

This is the final report of a programme of research which formed a part of the CEC joint research project into radionuclide migration in the geosphere (MIRAGE). This study addressed the aspects of integral migration and source term. The integral migration experiment simulated, in the laboratory, the intrusion of water into the repository, the leaching of radionuclides from two intermediate level wasteforms and the subsequent migration through the geosphere. The simulation consisted of a source of natural ground water which flowed over a sample of wasteform, at a controlled redox potential, and then through backfill and geological material packed in columns. The two wasteforms used here were cemented waste from the WAK plant at Karlsruhe, W. Germany and bitumenised intermediate concentrates from the Marcoule plant in France. The soluble fission products such as caesium wire rapidly released from the cemented waste but the actinides, and technetium in the reduced state, were retained in the wasteform. The release of all nuclides from the bitumenised waste was very low. (author)

Integral migration and source-term experiments on cement and bitumen waste forms

International Nuclear Information System (INIS)

Ewart, F.T.; Howse, R.M.; Sharpe, B.M.; Smith, A.J.; Thomason, H.P.; Williams, S.J.; Young, M.

1986-01-01

This is the final report of a programme of research which formed a part of the CEC joint research project into radionuclide migration in the geosphere (MIRAGE). This study addressed the aspects of integral migration and source term. The integral migration experiment simulated, in the laboratory, the intrusion of water into the repository, the leaching of radionuclides from two intermediate-level waste-forms and the subsequent migration through the geosphere. The simulation consisted of a source of natural ground water which flowed over a sample of waste-form, at a controlled redox potential, and then through backfill and geological material packed in columns. The two waste forms used here were cemented waste from the WAK plant at Karlsruhe in the Federal Republic of Germany and bitumenized intermediate concentrates from the Marcoule plant in France. The soluble fission products such as caesium were rapidly released from the cemented waste but the actinides, and technetium in the reduced state, were retained in the waste-form. The released of all nuclides from the bitumenized waste was very low

Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

DEFF Research Database (Denmark)

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

2004-01-01

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...

A DFT study on benzene adsorption over tungsten sulfides: surface model and adsorption geometries

NARCIS (Netherlands)

Koide, R.; Hensen, E.J.M.; Paul, J.F.; Cristol, S.; Payen, E.; Nakamura, H.; Santen, van R.A.

2007-01-01

Benzene adsorption on a WS2(100) surface was studied by ab initio periodic DFT computations. Benzene adsorption is facile on the bridge site of the bare W edge via ¿2 or ¿3 coordination. Taking into account the stable configuration at the W edge under typical hydrotreating reaction conditions (623

Cleavage of ST6Gal I by Radiation-Induced BACE1 Inhibits Golgi-Anchored ST6Gal I-Mediated Sialylation of Integrin β1 and Migration in Colon Cancer Cells

International Nuclear Information System (INIS)

Lee, Minyoung; Park, Jung-Jin; Ko, Young-Gyu; Lee, Yun-Sil

2012-01-01

Previously, we found that β-galactoside α2,6-sialyltransferase (ST6Gal I), an enzyme that adds sialic acids to N-linked oligosaccharides of glycoproteins and is frequently overexpressed in cancer cells, is up-regulated by ionizing radiation (IR) and cleaved to a form possessing catalytic activity comparable to that of the Golgi-localized enzyme. Moreover, this soluble form is secreted into the culture media. Induction of ST6Gal I significantly increased the migration of colon cancer cells via sialylation of integrin β1. Here, we further investigated the mechanisms underlying ST6Gal I cleavage, solubilization and release from cells, and addressed its functions, focusing primarily on cancer cell migration. We performed immunoblotting and lectin affinity assay to analyze the expression of ST6 Gal I and level of sialylated integrin β1. After ionizing radiation, migration of cells was measured by in vitro migration assay. α2, 6 sialylation level of cell surface was analyzed by flow cytometry. Cell culture media were concentrated and then analyzed for soluble ST6Gal I levels using an α2, 6 sialyltransferase sandwich ELISA. We found that ST6Gal I was cleaved by BACE1 (β-site amyloid precursor protein-cleaving enzyme), which was specifically overexpressed in response to IR. The soluble form of ST6Gal I, which also has sialyltransferase enzymatic activity, was cleaved from the Golgi membrane and then released into the culture media. Both non-cleaved and cleaved forms of ST6Gal I significantly increased colon cancer cell migration in a sialylation-dependent manner. The pro-migratory effect of the non-cleaved form of ST6Gal I was dependent on integrin β1 sialylation, whereas that of the cleaved form of ST6Gal I was not, suggesting that other intracellular sialylated molecules apart from cell surface molecules such as integrin β1 might be involved in mediating the pro-migratory effects of the soluble form of ST6Gal I. Moreover, production of soluble form ST6Gal I by

Sulfur tolerance of Pt/mordenites for benzene hydrogenation. Do Bronsted acid sites participate in hydrogenation?

NARCIS (Netherlands)

Simon, L.; van Ommen, J.G.; Jentys, A.; Lercher, J.A.

2002-01-01

The comparison of Pt electronic properties studied by in situ XANES and the kinetic study of benzene hydrogenation strongly suggests that the hydrogenation of benzene on Pt/mordenites occurs along two parallel reaction pathways. The routes proposed include (i) the monofunctional hydrogenation of

Adsorption Of Water And Benzene Vapour In Mesoporous Materials

Directory of Open Access Journals (Sweden)

Paulina Taba

2008-11-01

Full Text Available Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification. MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16 or MCM-41 (C12 respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16 and MCM-48 with trimethylchloro silane (MCM16-TMCS and MCM48-TMCS and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS. Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16 > MCM-48 > MCM-41 (C12. The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds.

Synthetic Method for Oligonucleotide Block by Using Alkyl-Chain-Soluble Support.

Science.gov (United States)

Matsuno, Yuki; Shoji, Takao; Kim, Shokaku; Chiba, Kazuhiro

2016-02-19

A straightforward method for the synthesis of oligonucleotide blocks using a Cbz-type alkyl-chain-soluble support (Z-ACSS) attached to the 3'-OH group of 3'-terminal nucleosides was developed. The Z-ACSS allowed for the preparation of fully protected deoxyribo- and ribo-oligonucleotides without chromatographic purification and released dimer- to tetramer-size oligonucleotide blocks via hydrogenation using a Pd/C catalyst without significant loss or migration of protective groups such as 5'-end 4,4'-dimethoxtrityl, 2-cyanoethyl on internucleotide bonds, or 2'-TBS.

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

OpenAIRE

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

2015-01-01

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

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Science.gov (United States)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O3 catalytic decomposition and utilization. Benzene and O3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O3 was catalytically decomposed, generating highly reactive oxidants such as rad OH and rad O for benzene oxidation.

Aqueous benzene-diols react with an organic triplet excited state and hydroxyl radical to form secondary organic aerosol.

Science.gov (United States)

Smith, Jeremy D; Kinney, Haley; Anastasio, Cort

2015-04-21

Chemical processing in atmospheric aqueous phases, such as cloud and fog drops, can play a significant role in the production and evolution of secondary organic aerosol (SOA). In this work we examine aqueous SOA production via the oxidation of benzene-diols (dihydroxy-benzenes) by the triplet excited state of 3,4-dimethoxybenzaldehyde, (3)DMB*, and by hydroxyl radical, ˙OH. Reactions of the three benzene-diols (catechol (CAT), resorcinol (RES) and hydroquinone (HQ)) with (3)DMB* or ˙OH proceed rapidly, with rate constants near diffusion-controlled values. The two oxidants exhibit different behaviors with pH, with rate constants for (3)DMB* increasing as pH decreases from pH 5 to 2, while rate constants with ˙OH decrease in more acidic solutions. Mass yields of SOA were near 100% for all three benzene-diols with both oxidants. We also examined the reactivity of atmospherically relevant mixtures of phenols and benzene-diols in the presence of (3)DMB*. We find that the kinetics of phenol and benzene-diol loss, and the production of SOA mass, in mixtures are generally consistent with rate constants determined in experiments containing a single phenol or benzene-diol. Combining our aqueous kinetic and SOA mass yield data with previously published gas-phase data, we estimate a total SOA production rate from benzene-diol oxidation in a foggy area with significant wood combustion to be nearly 0.6 μg mair(-3) h(-1), with approximately half from the aqueous oxidation of resorcinol and hydroquinone, and half from the gas-phase oxidation of catechol.

A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

Directory of Open Access Journals (Sweden)

Marco Tomatis

2018-03-01

Full Text Available Two commercial diatomaceous earths were used as supports for the preparation of Mn/Co binary metal catalysts at different metal loads (5 to 10 wt % Mn and 5 to 15 wt % Co by incipient wetness deposition. The activity of the prepared catalysts towards the complete oxidation of benzene to CO2 and water was investigated between 100 and 400 °C. Raw supports and synthesized catalysts were characterized by XRD, N2 physisorption, SEM-EDS, H2-TPR, and TPD. The purification treatment of food-grade diatomite significantly affected the crystallinity of this support while reducing its specific surface area (SSA. A loss of SSA, associated with the increase in the metal load, was observed on samples prepared on natural diatomite, while the opposite trend occurred with food-grade diatomite-supported catalysts. Metal nanoparticles of around 50 nm diameter were observed on the catalysts’ surface by SEM analysis. EDS analysis confirmed the uniform deposition of the active phases on the support’s surface. A larger H2 consumption was found by TPR analysis of natural diatomite-based samples in comparison to those prepared at the same metal load on food-grade diatomite. During the catalytic oxidation experiment, over 90% conversion of benzene were achieved at a reaction temperature of 225 °C by all of the prepared samples. In addition, the formation of coke during the oxidation tests was demonstrated by TGA analysis and the soluble fraction of the produced coke was characterized by GC-MS.

Significance of calculated cluster conformations of benzene: comment on a publication by D. E. Williams

NARCIS (Netherlands)

van de Waal, B.W.

1981-01-01

Results of potential-energy minimization, applied to clusters of benzene molecules, have been reported recently by Williams [Acta Cryst. (1980), A36, 715-723]. Two stable tridecamer clusters were found and compared with a 13-molecule fragment from crystalline orthorhombic benzene. In this comment

"Plug-and-Play" potentials: Investigating quantum effects in (H2)2-Li+-benzene

Science.gov (United States)

D'Arcy, Jordan H.; Kolmann, Stephen J.; Jordan, Meredith J. T.

2015-08-01

Quantum and anharmonic effects are investigated in (H2)2-Li+-benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H2 molecule to the H2-Li+-benzene complex increases the ZPE of the system by 5.6 kJ mol-1 to 17.6 kJ mol-1. This ZPE is 42% of the total electronic binding energy of (H2)2-Li+-benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H2 to H2-Li+-benzene is 7.7 kJ mol-1, compared to 12.4 kJ mol-1 for the first H2 molecule. Anharmonicity is found to be even more important when a second (and subsequent) H2 molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H2 molecules are found at larger distance from the Li+ ion and are more confined in the θ coordinate than in H2-Li+-benzene. They also show that both H2 molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H2 molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H2)2-Li+-benzene PESs are developed. These use a modified Shepard interpolation for the Li+-benzene and H2-Li+-benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H2-H2 interaction. Because of the neglect of three-body H2, H2, Li+ terms, both fragment PESs lead to overbinding of the second H2 molecule by 1.5 kJ mol-1. Probability density histograms, however, indicate that the wavefunctions for the two H2 molecules are effectively identical on the "full" and fragment PESs. This suggests that the 1.5 kJ mol-1 error is

"Plug-and-Play" potentials: Investigating quantum effects in (H2)2-Li(+)-benzene.

Science.gov (United States)

D'Arcy, Jordan H; Kolmann, Stephen J; Jordan, Meredith J T

2015-08-21

Quantum and anharmonic effects are investigated in (H2)2-Li(+)-benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H2 molecule to the H2-Li(+)-benzene complex increases the ZPE of the system by 5.6 kJ mol(-1) to 17.6 kJ mol(-1). This ZPE is 42% of the total electronic binding energy of (H2)2-Li(+)-benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H2 to H2-Li(+)-benzene is 7.7 kJ mol(-1), compared to 12.4 kJ mol(-1) for the first H2 molecule. Anharmonicity is found to be even more important when a second (and subsequent) H2 molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H2 molecules are found at larger distance from the Li(+) ion and are more confined in the θ coordinate than in H2-Li(+)-benzene. They also show that both H2 molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H2 molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H2)2-Li(+)-benzene PESs are developed. These use a modified Shepard interpolation for the Li(+)-benzene and H2-Li(+)-benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H2-H2 interaction. Because of the neglect of three-body H2, H2, Li(+) terms, both fragment PESs lead to overbinding of the second H2 molecule by 1.5 kJ mol(-1). Probability density histograms, however, indicate that the wavefunctions for the two H2 molecules are effectively identical on the "full" and fragment PESs. This suggests that

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

Energy Technology Data Exchange (ETDEWEB)

Hung-Lung Chiang; Kuo-Hsiung Lin; Chih-Yu Chen; Ching-Guan Choa; Ching-Shyung Hwu; Nina Lai [China Medical University, Taichung (Taiwan). Department of Risk Management

2006-05-15

This study selected biosolids from a petrochemical wastewater treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl{sub 2}) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl{sub 2}-immersed biosolids pyrolyzed at 500{sup o}C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high. 18 refs., 9 figs., 3 tabs.

Fractionation of benzene/n-hexane mixtures by pervaporation using polyurethane membranes

Directory of Open Access Journals (Sweden)

CUNHA V. S.

1999-01-01

Full Text Available In the present work polyurethane membranes obtained from different polyester/MDI-based polymers were used to separate benzene/n-hexane mixtures by pervaporation. In pervaporation experiments, with a 50% wt feed at room temperature, permeate fluxes in the range of 0.3 to 3.2 Kg/m2h (10 mm membrane thickness and selectivity in the range of 3.8 to 5.6 were obtained. The permeate was always enriched in benzene. Taking into account the compromise between flux and selectivity, the best performance membrane was selected for complementary sorption and pervaporation experiments. Results show that selectivity increases and the permeation flux decreases when the benzene concentration in the feed decreases. In the present application, results also show that sorption is the main factor for selectivity. Using the distillation azeotropic mixture as feed, almost no influence of temperature on selectivity was observed in the range of 25oC to 56oC. The permeate flux increases seven-fold, while selectivity remains constant near 8.0.

The comparison of benzene and CO2 absorption methods for radioisotope 14C dating

International Nuclear Information System (INIS)

Satrio and Zainal Abidin

2007-01-01

It had been conducted to research of age determination of carbon samples using CO 2 absorption method. This method as alternative to benzene synthesis method for radioisotope 14 C dating.The aim of the method is to support some hydrology research's especially groundwater dating using environmental radioisotope 14 C.The results which obtain by CO 2 absorption method then compared with the results of benzene synthesis method consists of background counter, standard counter, activity and age limit, age, and material cost or component. The research show that compared with benzene synthesis method, sample preparation using CO 2 absorption method is more simple and relatively low cost. The use of CO 2 absorption method can save the cost about 75 %. The different of both methods is age limit detection. The results of age limit detection when using CO 2 absorption and synthesis benzene methods are 33,310 years and 47,533 years respectively. Whereas, based on t test, the age results of both methods for the same sample are obtained relatively equal. (author)

ON THE FORMATION OF BENZOIC ACID AND HIGHER-ORDER BENZENE CARBOXYLIC ACIDS IN INTERSTELLAR MODEL ICE GRAINS

Energy Technology Data Exchange (ETDEWEB)

McMurtry, Brandon M.; Saito, Sean E. J.; Turner, Andrew M.; Chakravarty, Harish K.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2016-11-10

With a binary ice mixture of benzene (C{sub 6}H{sub 6}) and carbon dioxide (CO{sub 2}) 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.

Catalytic transformation of methyl benzenes over zeolite catalysts

KAUST Repository

Al-Khattaf, S.; Akhtar, M. N.; Odedairo, T.; Aitani, A.; Tukur, N. M.; Kubů, M.; Musilová -Pavlačková , Z.; Čejka, J.

2011-01-01

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

Plutonium solubilities

International Nuclear Information System (INIS)

Puigdomnech, I.; Bruno, J.

1991-02-01

Thermochemical data has been selected for plutonium oxide, hydroxide, carbonate and phosphate equilibria. Equilibrium constants have been evaluated in the temperature range 0 to 300 degrees C at a pressure of 1 bar to T≤100 degrees C and at the steam saturated pressure at higher temperatures. Measured solubilities of plutonium that are reported in the literature for laboratory experiments have been collected. Solubility data on oxides, hydroxides, carbonates and phosphates have been selected. No solubility data were found at temperatures higher than 60 degrees C. The literature solubility data have been compared with plutonium solubilities calculated with the EQ3/6 geochemical modelling programs, using the selected thermodynamic data for plutonium. (authors)

Radionuclide distributions and migration mechanisms at shallow land burial sites. Annual report of research investigations on the distribution, migration and containment of radionuclides at Maxey Flats, Kentucky

International Nuclear Information System (INIS)

Kirby, L.J.

1982-07-01

Subsurface waters at Maxey Flats are anoxic systems with high alkalinity and high concentrations of dissolved ferrous ion. Americium and cobalt in these trench waters are made more soluble by the presence of EDTA, while strontium and cesium are unaffected under the same conditions. EDTA is the major organic complexing component in waste trench 27 leachate, but other polar, water-soluble organics are also present. Evidence points to the migration of plutonium between waste trench 27 and inert atmosphere wells as an EDTA complex. Polar organic compounds may influence the migration of 90 Sr and 137 Cs. The primary pathway of water entry into the waste burial trenches is through the trench caps, but major increases in water level have occurred in an experimental trench by subsurface flow. The areal distribution of radionuclides at Maxey Flats has been influenced by surface runoff, deposition from the evaporator plume, subsurface flow and the actions of burrowing animals or deep-rooted trees. Vegetal and surface contamination on site and near site are quite low, and only 60 Co exceeds commonly observed fallout levels. Radionuclide concentrations in surface soil at Maxey Flats are comparable to concentrations resulting from normal fallout in other areas of high rainfall

Soluble vascular endothelial growth factor (VEGF) receptor-1 inhibits migration of human monocytic THP-1 cells in response to VEGF.

Science.gov (United States)

Zhu, Cansheng; Xiong, Zhaojun; Chen, Xiaohong; Lu, Zhengqi; Zhou, Guoyu; Wang, Dunjing; Bao, Jian; Hu, Xueqiang

2011-08-01

We aimed to investigate the regulation and contribution of vascular endothelial growth factor (VEGF) and sFlt-1(1-3) to human monocytic THP-1 migration. Ad-sFlt-1/FLAG, a recombinant adenovirus carrying the human sFlt-1(1-3) (the first three extracellular domains of FLT-1, the hVEGF receptor-1) gene, was constructed. L929 cells were infected with Ad-sFlt-1/FLAG and the expression of sFlt-1 was detected by immunofluorescent assay and ELISA. Corning(®) Transwell(®) Filter Inserts containing polyethylene terephthalate (PET) membranes with pore sizes of 3 μm were used as an experimental model to simulate THP-1 migration. Five VEGF concentrations (0, 0.1, 1, 10 and 100 ng/ml), four concentrations of sFlt-1(1-3)/FLAG expression supernatants (0.1, 1, 10 and 100 ng/ml), and monocyte chemoattractant protein-1 (MCP-1, 10 ng/ml) were used to test the ability of THP-1 cells to migrate through PET membranes. The sFlt-1(1-3) gene was successfully recombined into Ad-sFlt-1/FLAG. sFlt-1(1-3) was expressed in L929 cells transfected with Ad-sFlt-1/FLAG. THP-1 cell migration increased with increasing concentrations of VEGF, while cell migration decreased with increasing concentrations of sFlt1(1-3)/FLAG. sFlt1(1-3)/FLAG had no effect on MCP-1-induced cell migration. This study demonstrated that VEGF is able to elicit a migratory response in THP-1 cells, and that sFlt-1(1-3) is an effective inhibitor of THP-1 migration towards VEGF.

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

Directory of Open Access Journals (Sweden)

Zhengfang Zeng

2010-07-01

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.

Kriged and modeled ambient air levels of benzene in an urban environment: an exposure assessment study

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Lai Dejian

2011-03-01

Full Text Available Abstract Background There is increasing concern regarding the potential adverse health effects of air pollution, particularly hazardous air pollutants (HAPs. However, quantifying exposure to these pollutants is problematic. Objective Our goal was to explore the utility of kriging, a spatial interpolation method, for exposure assessment in epidemiologic studies of HAPs. We used benzene as an example and compared census tract-level kriged predictions to estimates obtained from the 1999 U.S. EPA National Air Toxics Assessment (NATA, Assessment System for Population Exposure Nationwide (ASPEN model. Methods Kriged predictions were generated for 649 census tracts in Harris County, Texas using estimates of annual benzene air concentrations from 17 monitoring sites operating in Harris and surrounding counties from 1998 to 2000. Year 1999 ASPEN modeled estimates were also obtained for each census tract. Spearman rank correlation analyses were performed on the modeled and kriged benzene levels. Weighted kappa statistics were computed to assess agreement between discretized kriged and modeled estimates of ambient air levels of benzene. Results There was modest correlation between the predicted and modeled values across census tracts. Overall, 56.2%, 40.7%, 31.5% and 28.2% of census tracts were classified as having 'low', 'medium-low', 'medium-high' and 'high' ambient air levels of benzene, respectively, comparing predicted and modeled benzene levels. The weighted kappa statistic was 0.26 (95% confidence interval (CI = 0.20, 0.31, indicating poor agreement between the two methods. Conclusions There was a lack of concordance between predicted and modeled ambient air levels of benzene. Applying methods of spatial interpolation for assessing exposure to ambient air pollutants in health effect studies is hindered by the placement and number of existing stationary monitors collecting HAP data. Routine monitoring needs to be expanded if we are to use these data

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

DEFF Research Database (Denmark)

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

2012-01-01

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...

Epigenetic and Transcriptional Modifications in Repetitive Elements in Petrol Station Workers Exposed to Benzene and MTBE

Directory of Open Access Journals (Sweden)

Federica Rota

2018-04-01

Full Text Available Benzene, a known human carcinogen, and methyl tert-butyl ether (MTBE, not classifiable as to its carcinogenicity, are fuel-related pollutants. This study investigated the effect of these chemicals on epigenetic and transcriptional alterations in DNA repetitive elements. In 89 petrol station workers and 90 non-occupationally exposed subjects the transcriptional activity of retrotransposons (LINE-1, Alu, the methylation on repeated-element DNA, and of H3K9 histone, were investigated in peripheral blood lymphocytes. Median work shift exposure to benzene and MTBE was 59 and 408 µg/m3 in petrol station workers, and 4 and 3.5 µg/m3, in controls. Urinary benzene (BEN-U, S-phenylmercapturic acid, and MTBE were significantly higher in workers than in controls, while trans,trans-muconic acid (tt-MA was comparable between the two groups. Increased BEN-U was associated with increased Alu-Y and Alu-J expression; moreover, increased tt-MA was associated with increased Alu-Y and Alu-J and LINE-1 (L1-5′UTR expression. Among repetitive element methylation, only L1-Pa5 was hypomethylated in petrol station workers compared to controls. While L1-Ta and Alu-YD6 methylation was not associated with benzene exposure, a negative association with urinary MTBE was observed. The methylation status of histone H3K9 was not associated with either benzene or MTBE exposure. Overall, these findings only partially support previous observations linking benzene exposure with global DNA hypomethylation.

Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs

Science.gov (United States)

Quitián-Lara, Heidy M.; Fantuzzi, Felipe; Nascimento, Marco A. C.; Wolff, Wania; Boechat-Roberty, Heloisa M.

2018-02-01

Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C6H6) rings, emit infrared radiation (3–12 μm) due to the vibrational transitions of the C–H bonds of the aromatic rings. The 3.3 μm aromatic band is generally accompanied by the band at 3.4 μm assigned to the vibration of aliphatic C–H bonds of compounds such as PAHs with an excess of peripheral H atoms (H n –PAHs). Herein we study the stability of fully hydrogenated benzene (or cyclohexane, C6H12) under the impact of stellar radiation in the photodissociation region (PDR) of NGC 7027. Using synchrotron radiation and time-of-flight mass spectrometry, we investigated the ionization and dissociation processes at energy ranges of UV (10–200 eV) and soft X-rays (280–310 eV). Density Functional Theory (DFT) calculations were used to determine the most stable structures and the relevant low-lying isomers of singly charged C6H12 ions. Partial Ion Yield (PIY) analysis gives evidence of the higher tendency toward dissociation of cyclohexane in comparison to benzene. However, because of the high photoabsorption cross-section of benzene at the C1s resonance edge, its photodissociation and photoionization cross-sections are enhanced, leading to a higher efficiency of dissociation of benzene in the PDR of NGC 7027. We suggest that a similar effect is experienced by PAHs in X-ray photon-rich environments, which ultimately acts as an auxiliary protection mechanism of super-hydrogenated polycyclic hydrocarbons. Finally, we propose that the single photoionization of cyclohexane could enhance the abundance of branched molecules in interstellar and circumstellar media.

Nitration of benzene with N{sub 2}O{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Furukawa, Kikuo; Yoshizawa, FUjiroku; Akutsu, Yoshiaki; Arai, Mitsuru; Tamura, Masamitsu [The University of Tokyo, Tokyo (Japan). School of Engineering

1999-08-31

In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitrations of benzene and of nitrobenzene with N{sub 2}O{sub 5} were carried out and the yield of the products and the isomer distribution of dinitrobenzenes were investigated. As a result, the isomer distribution of the dinitrobenzenes in the nitration of benzene was quite different from that in the nitration of nitrobenzene. Moreover, the ratio of [dinitrobenzenes]/[nitrobenzene] increased with the reaction temperature. The nitration of benzene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out and showed the dependence of the ratio of [dinitrobenzenes]/[nitrobenzene] on the ratio of N{sub 2}O{sub 4}. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4}, that the aromatic nitration with N{sub 2}O{sub 5} over 25 degree C should produce a large amount of N{sub 2}O{sub 4}(2NO{sub 2}) and the attack of NO{sub 2} on the intermediate [Ar(H)(ONO{sub 2})] should form the intermediates [Ar(H)(ONO{sub 2})(H)(NO{sub 2})] following the production of a large amount of dinitrobenzenes. (author)

Solubility study of Tc(IV) in a granitic water

International Nuclear Information System (INIS)

Liu, D.J.; Yao, J.; Wang, B.; Bruggeman, C.; Maes, N.

2007-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safe disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 .nH 2 O. Hence, the mobility of Tc(IV) in reducing groundwater may be limited by the solubility of TcO 2 .nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 .nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium(IV) was prepared by reduction of a technetate solution with Sn 2+ . The solubility of Tc(IV) has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(IV) were studied. The concentration of total technetium and Tc(IV) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(IV) in simulated groundwater and redistilled water is about (1.49 ∝ 1.86) x 10 -9 mol L -1 d -1 under aerobic conditions, while no Tc(IV) oxidation was detected in simulated groundwater and redistilled water under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(IV) in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

Desaturation reactions catalyzed by soluble methane monooxygenase.

Science.gov (United States)

Jin, Y; Lipscomb, J D

2001-09-01

Soluble methane monooxygenase (MMO) is shown to be capable of catalyzing desaturation reactions in addition to the usual hydroxylation and epoxidation reactions. Dehydrogenated products are generated from MMO-catalyzed oxidation of certain substrates including ethylbenzene and cyclohexadienes. In the reaction of ethylbenzene, desaturation of ethyl C-H occurred along with the conventional hydroxvlations of ethyl and phenyl C-Hs. As a result, styrene is formed together with ethylphenols and phenylethanols. Similarly, when 1,3- and 1,4-cyclohexadienes were used as substrates, benzene was detected as a product in addition to the corresponding alcohols and epoxides. In all cases, reaction conditions were found to significantly affect the distribution among the different products. This new activity of MMO is postulated to be associated with the chemical properties of the substrates rather than fundamental changes in the nature of the oxygen and C-H activation chemistries. The formation of the desaturated products is rationalized by formation of a substrate cationic intermediate, possibly via a radical precursor. The cationic species is then proposed to partition between recombination (alcohol formation) and elimination (alkene production) pathways. This novel function of MMO indicates close mechanistic kinship between the hydroxylation and desaturation reactions catalyzed by the nonheme diiron clusters.

Managing Exposure to Benzene and Total Petroleum Hydrocarbons at Two Oil Refineries 1977–2014

Science.gov (United States)

Tuomi, Tapani; Veijalainen, Henna; Santonen, Tiina

2018-01-01

Air concentrations of and inhalation exposure to total petroleum hydrocarbons (TPH) and benzene was monitored separately at two oil refineries from 1977 to 2014. Prevention policies and control measures that may explain changes were surveyed. The aim was to evaluate how the application of of Occupational Health and Safety Assessment Series OHSAS 18001.04 principles as well as Environmental protection Agency EPA and European Oil Company Organisation for Environment, Health and Safety CONCAWE practices have influenced air concentrations. Benzene air concentrations declined in 11 of 17 units, six of which were associated with declining exposures. Benzene air concentrations declined across all units on average by 46%. This amounts to an average yearly decline of 1.7%. TPH air concentrations declined in 10 of 17 units, seven of which were associated with declining exposures. The average decline in TPH air concentrations was 49%, corresponding to 1.3% per year. As a result, average working day exposure in 10 of 17 units have declined significantly and today, benzene and TPH exposure in most units are well below 10% of the current Occupational Exposure Limit (OEL8h:s). A decline in air concentrations have coincided with consistent implementation of control measures. Such measures include on-line monitoring of leaks; benzene recovery; floating container roofs; improved valves and seals; hermetic pumps; recovery of loading gases and instalment of torches in terminals; cutback in coke combustion; a new production line spanning directly from the dock to aromatics production; and recovery of loading gases in the doc. Other tools in exposure management include personal leak monitors, on-line measurements, monitoring campaigns, risk assessment, and availability and user training of protective equipment. However, improvements are still needed. Hydrocarbon or benzene air concentrations have not declined in 8 of 17 units, in some of which concentrations exceed 10% of the relevant

Electronic structure of molecules of substituted benzenes by x-ray spectroscopy. I. Nitrobenzene

International Nuclear Information System (INIS)

Yumatov, V.D.; Murakhtanov, V.V.; Salakhutdinov, N.F.; Okotrub, A.V.; Mazalov, L.N.; Logunova, L.G.; Koptyug, V.A.; Furin, G.G.

1988-01-01

The electronic structure of the nitrobenzene molecule has been studied by x-ray spectroscopy with the aid of quantum-chemical calculations. The structure of the molecular orbitals of nitrobenzene has been compared with the structure of benzene and nitrogen dioxide. It has been shown in the framework of a fragment-by-fragment analysis that the interaction of the highest occupied π orbitals of the benzene ring and the nitro group is weak

Ceramic membrane ozonator for soluble organics removal from produced water

Science.gov (United States)

Siagian, U. W. R.; Dwipramana, A. S.; Perwira, S. B.; Khoiruddin; Wenten, I. G.

2018-01-01

In this work, the performance of ozonation for degradation of soluble organic compounds in produced water was investigated. Tubular ceramic membrane diffuser (with and without a static mixer in the lumen side) was used to facilitate contact between ozone and produced water. The ozonation was conducted at ozone flow rate of 8 L.min-1, ozone concentration of 0.4 ppm, original pH of the solution, and pressure of 1.2 bar, while the flow rates of the produced water were varied (192, 378 and 830 mL.min-1). It was found that the reduction of benzene, toluene, ethylbenzene, and xylene were 85%, 99%, 85%, and 95%, respectively. A lower liquid flow rate in a laminar state showed a better component reduction due to the longer contacting time between the liquid and the gas phase. The introduction of the static mixer in the lumen side of the membrane as a turbulence promoter provided a positive effect on the performance of the membrane diffuser. The twisted static mixer exhibited the better removal rate than the spiral static mixer.

FORMATION OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE IN MOUSE, RAT, AND HUMAN BLOOD

Science.gov (United States)

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, ...

The separation of radionuclide migration by solution and particle transport in LLRW repository buffer material

International Nuclear Information System (INIS)

Torok, J.; Buckley, L.P.; Woods, B.L.

1989-01-01

Laboratory-scale lysimeter experiments were performed with simulated waste forms placed in candidate buffer materials which have been chosen for a low-level radioactive waste repository. Radionuclide releases into the effluent water and radionuclide capture by the buffer material were determined. The results could not be explained by traditional solution transport mechanisms, and transport by particles released from the waste form and/or transport by buffer particles were suspected as the dominant mechanism for radionuclide release from the lysimeters. To elucidate the relative contribution of particle and solution transport, the waste forms were replaced by a wafer of neutron-activated buffer soaked with selected soluble isotopes. Particle transport was determined by the movement of gamma-emitting neutron-activation products through the lysimeter. Solution transport was quantified by comparing the migration of soluble radionuclides relative to the transport of neutron activation products. The new approach for monitoring radionuclide migration in soil is presented. It facilitates the determination of most of the fundamental coefficients required to model the transport process

Metabolism of benzene and phenol by a reconstituted purified phenobarbital induced rat liver mixed function oxidase system

International Nuclear Information System (INIS)

Griffiths, J.C.

1986-01-01

Cytochrome P-450 and the electron-donor, NADPH-cytochrome c reductase were isolated from phenobarbital induced rat liver microsomes. Both benzene and its primary metabolite phenol, were substrates for the reconstituted purified phenobarbital induced rat liver mixed function oxidase system. Benzene was metabolized to phenol and the polyhydroxylated metabolites; catechol, hydroquinone and 1,2,4 benzenetriol. Benzene elicited a Type I spectral change upon its interaction with the cytochrome P-450 while phenol's interaction with the cytochrome P-450 produced a reverse Type I spectra. The formation of phenol showed a pH optimum of 7.0 compared with 6.6-6.8 for the production of the polyhyrdoxylated metabolites. Cytochrome P-450 inhibitors, such as metyrapone and SKF 525A, diminished the production of phenol from benzene but not the production of the polyhydroxylated metabolites from phenol. The radical trapping agents, DMSO, KTBA and mannitol, decreased the recovery of polyhydroxylated metabolites, from 14 C-labeled benzene and/or phenol. As KTBA and DMSO interacted with OH. There was a concomitant release of ethylene and methane, which was measured. Desferrioxamine, an iron-chelator and catalase also depressed the recovery of polyhydroxylated metabolites. In summary, benzene and phenol were both substrates for this reconstituted purified enzyme system, but they differed in binding to cytochrome P-450, pH optima and mode of hydroxylation

Molecular Self-Assembly of Group 11 Pyrazolate Complexes as Phosphorescent Chemosensors for Detection of Benzene

Science.gov (United States)

Ghazalli, N. F.; Yuliati, L.; Lintang, H. O.

2018-01-01

We highlight the systematic study on vapochromic sensing of aromatic vapors such as benzene using phosphorescent trinuclear pyrazolate complexes (2) with supramolecular assembly of a weak intermolecular metal-metal interaction consisting of 4-(3,5-dimethoxybenzyl)-3,5-dimethyl pyrazole ligand (1) and group 11 metal ions (Cu(I), Ag(I), Au(I)). The resulting chemosensor 2(Cu) revealed positive response to benzene vapors in 5 mins by blue-shifting its emission band in 44 nm (from 616 to 572 nm) and emitted bright orange to green, where this change cannot be recovered even with external stimuli. Comparing to 2(Ag) with longer metal-metal distance (473 nm) with same sensing time and quenching in 37%, 2(Au) gave quenching in 81% from its original intensity at 612 nm with reusability in 82% without external stimuli and emitted less emissive of red-orange from its original color. The shifting phenomenon in 2(Cu) suggests diffusion of benzene vapors to inside molecules for formation of intermolecular interaction with Cu(I)-Cu(I) interaction while quenching phenomenon in 2(Au) suggests diffusion of benzene vapors to between the Au(I)-Au(I) interaction. These results indicate that suitable molecular structure of ligand and metal ion in pyrazolate complex is important for designing chemosensor in the detection of benzene vapors.

Mechanisms of free radical chemistry and biochemistry of benzene

International Nuclear Information System (INIS)

Karam, L.R.; Simic, M.G.

1989-01-01

o-Tyrosine (o-Tyr) was used as a specific biomarker for OH radicals generated in biosystems. Specificity of o-Tyr as an OH biomarker was based on previous studied in systems exposed to ionizing radiations. Fresh muscle tissue incubated with benzene for 1 hr at 38 degree C exhibits formation of o-Tyr as seen in the cases of ethanol- and carbon tetrachloride-exposed systems. Gas chromatography/mass spectrometry selective ion monitoring measurements of o-Tyr yields in chicken breast muscle incubated with water or benzene indicate levels of less than 0.1 ppm and 3.0 ± 0.5 ppm of o-Tyr, respectively. Formation of OH is presumed to originate via a Haber-Weiss reaction of H 2 O 2 with Fe (II) preceded by the formation of O 2 and H 2 O 2 from distorted mitochondria

40 CFR 80.1352 - What are the pre-compliance reporting requirements for the gasoline benzene program?

Science.gov (United States)

2010-07-01

...) Benzene concentration. An estimate of the average gasoline benzene concentration corresponding to the time... engineering and permitting, Procurement and Construction, and Commissioning and startup. (7) Basic information regarding the selected technology pathway for compliance (e.g., precursor re-routing or other technologies...

Environmental exposure to benzene: an update.

OpenAIRE

Wallace, L

1996-01-01

During the 1990s, several large-scale studies of benzene concentrations in air, food, and blood have added to our knowledge of its environmental occurrence. In general, the new studies have confirmed the earlier findings of the U.S. Environmental Protection Agency Total Exposure Assessment Methodology (TEAM) studies and other large-scale studies in Germany and the Netherlands concerning the levels of exposure and major sources. For example, the new studies found that personal exposures exceed...

Analytical methods being used to study the course of the catalytic reforming of benzene

Energy Technology Data Exchange (ETDEWEB)

Holle, B; Svajgl, O

1980-01-01

Methods published in the literature and worked out at the national Institute for the Chemical Processing of Coal are examined. These are methods of observation to take place during catalytic reforming, and the following are necessary; methods of group analysis of benzenes (with boiling points of 90-205/sup 0/, determination of S, N, Pb, and C1 impurities and water impurities in the liquid and gas tests, which result from the reforming process. The Institute's proposed methods of analyzing the group composition of benzenes and determining the S, N, Pb, chloride and water present are described. A comparison is made between the results of the analysis of the group composition of fractions and Rumanian benzene using the Institute's method, and the results' of well-known methods. To investigate the amount of raw material and the products of the reforming, a universal automatic colorimeter was developed. Analysis of the group composition of benzenes using the Institute's method is done by determining certain oil-product characteristics, determing S using an oxidizing and reduction method, determining lead using flameless atomic absorption in a graphitization trough, determining chlorides through acidic mineralization, and determining water using a colorimetric method.

Solubility study of Tc(Ⅳ) in a granitic water

International Nuclear Information System (INIS)

Liu Dejun; Yao Jun; Wang Bo

2008-01-01

The deep geological disposal of the high level radioactive wastes is expected to be a safe disposal method in most countries. The long-lived fission product 99 Tc is present in large quantities in nuclear wastes and its chemical behavior in aqueous solution is of considerable interest. Under oxidizing conditions technetium exists as the anionic species TcO 4 - whereas under the reducing conditions, expected to exist in a deep geological repository, it is generally predicted that technetium will be present as TcO 2 -nH 2 O. Hence, the mobility of Tc(Ⅳ) in reducing groundwater may be limited by the solubility of TcO 2 ·nH 2 O under these conditions. Due to this fact it is important to investigate the solubility of TcO 2 ·nH 2 O. The solubility determines the release of radionuclides from waste form and is used as a source term in radionuclide migration analysis in performance assessment of radioactive waste repository. Technetium (Ⅳ) was prepared by reduction of a technetate solution with Sn 2+ . The solubility of Tc(Ⅳ) has been determined in simulated groundwater and redistilled water under aerobic and anaerobic conditions. The effects of pH and CO 3 2- concentration of solution on solubility of Tc(Ⅳ) were studied. The concentration of total technetium and Tc(Ⅳ) species in the solutions were periodically determined by separating the oxidized and reduced technetium species using a solvent extraction procedure and counting the beta activity of the 99 Tc with a liquid scintillation counter. The experimental results show that the rate of oxidation of Tc(Ⅳ) in simulated groundwater and redistilled water is about (1.49-1.86)x10 -9 mol·L -1 d -1 under aerobic conditions, while no Tc(Ⅳ) oxidation was detected in simulated groundwater and redistilled water under anaerobic conditions. Under aerobic or anaerobic conditions the solubility of Tc(Ⅳ) in simulated groundwater and redistilled water is equal on the whole after centrifugation or ultrafiltration. The

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

OpenAIRE

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

2016-01-01

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

Deuteration of benzen derivatives and condensed aromatics

International Nuclear Information System (INIS)

Ichikawa, Masaru.

1970-01-01

A process for the deuteration of aromatic compounds (benzene derivatives having one or more cyano, halogeno, nitro or other electron attractive groups, and condensed ring aromatics) is provided. The process comprises reducing said aromatic compound with an alkali metal (preferably K, Rb or Cs) in a solvent (dimethoxyethane, tetrahydrofuran, etc.) to provide an electron-acceptor-donor complex, which is followed by introducing gaseous deuterium into the solution. The deuteration takes place selectively at the position of highest electron density in accordance with nature of the substituent, regardless of steric hindrance. The process is applicable to a wide variety of aromatics to give deuterated compounds in high yields. In one example, 5x10 -3 mole of anthracene (An) was reacted with 2g of metallic potassium in 80cc of dimethoxyethane in a N 2 atmosphere. Into the resulting solution of An=2K + was introduced D 2 gas (30 cmHg) at 25 0 C. After decomposition with air and washing with alcohol, the precipitate was recrystallized from benzene. Yield of recovered AN: more than 90%. Yield of deuteration: 100%. Position of deuteration: 9 and 10 (revealed by NMR and mass spectroscopy). (Kaichi, S.)

Sonochemical treatment of benzene/toluene contaminated wastewater

Energy Technology Data Exchange (ETDEWEB)

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

1998-12-31

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

Indolent B-Cell Lymphoid Malignancy in the Spleen of a Man Who Handled Benzene: Splenic Marginal Zone Lymphoma

Directory of Open Access Journals (Sweden)

Jihye Lee

2017-09-01

Full Text Available We present the case of a 45-year-old man with a history of benzene exposure who developed splenic marginal zone lymphoma. For 6 years, he had worked in an enclosed space cleaning instruments with benzene. He was diagnosed with splenic marginal zone lymphoma 19 years after retirement. During his time of working in the laboratory in the 1980s, working environments were not monitored for hazardous materials. We indirectly estimated the cumulative level of past benzene exposure using job-exposure matrices and technical assumptions. Care must be taken in investigating the relevance of occupational benzene exposure in the occurrence of indolent B-cell lymphoma. Because of the long latency period and because occupational measurement data do not exist for the period during the patient's exposure, the epidemiological impact of benzene exposure may be underestimated.

Biomonitoring-based exposure assessment of benzene, toluene, ethylbenzene and xylene among workers at petroleum distribution facilities.

Science.gov (United States)

Heibati, Behzad; Godri Pollitt, Krystal J; Charati, Jamshid Yazdani; Ducatman, Alan; Shokrzadeh, Mohammad; Karimi, Ali; Mohammadyan, Mahmoud

2018-03-01

Elevated emissions of volatile organic compounds, including benzene, toluene, ethylbenzene, and o, p, and m-xylenes (BTEX), are an occupational health concern at oil transfer stations. This exploratory study investigated personal exposure to BTEX through environmental air and urine samples collected from 50 male workers at a major oil distribution company in Iran. Airborne BTEX exposures were evaluated over 8h periods during work-shift by using personal passive samplers. Urinary BTEX levels were determined using solid-phase microextraction with gas chromatography mass spectrometry for separation and detection. Mean exposure to ambient concentrations of benzene differed by workers' job type: tanker loading workers (5390μg/m 3 ), tank-gauging workers (830μg/m 3 ), drivers (81.9μg/m 3 ), firefighters (71.2μg/m 3 ) and office workers (19.8μg/m 3 ). Exposure across job type was similarly stratified across all personal exposures to BTEX measured in air samples with maximum concentrations found for tanker loading workers. Average exposures concentrations of BTEX measured in urine were 11.83 ppb benzene, 1.87 ppb toluene, 0.43 ppb ethylebenzene, and 3.76 ppb xylene. Personal air exposure to benzene was found to be positively associated with benzene concentrations measured in urine; however, a relationship was not observed to the other BTEX compounds. Urinary exposure profiles are a potentially useful, noninvasive, and rapid method for assessing exposure to benzene in a developing and relatively remote production region. Copyright © 2017 Elsevier Inc. All rights reserved.

Migration of hydrocarbons in the subsoil of an industrial installation; Migration d'hydrocarbures dans le sous-sol d'une installation industrielle

Energy Technology Data Exchange (ETDEWEB)

Van Dorpe, F [CEA Cadarache, Dept. d' Entreposage et de Stockage des Dechets (DCC/DESD/SEP), 13 - Saint-Paul-lez-Durance (France); Centre National de Recherche sur les Sites et Sols Pollues (CNRSSP), 59 - Douai (France)

2000-07-01

The fate of old industrial sites is a major problem at the beginning of the new millennium for government organization, agencies owning polluted sites... These brown-field sites often generate considerable pollution of soils and groundwater, the main source of drinking water. The National Center for Research on Polluted Soils and Sites (CNRSSP), in which the CEA is an active partner, is developing a strategy to study and, using several scientific tools, characterize industrial sites polluted by various contaminants: metals, metalloids, hydrocarbons, nitrates. The present study offers an example of the investigation of an old industrial site (coke plant), built in 1919 (in operation for 50 years), located in northern France. The storage of tars and wastewaters on these sites causes soil and groundwater contamination with organic compounds such as Polycyclic Aromatic Hydrocarbons (PAHs), mono-aromatic hydrocarbons (benzene, toluene, ethyl-benzene and xylene BTEX), volatile organic compounds (VOCs), phenolic and other hydrocarbons, and inorganic compounds including metalloids (free and complexed cyanides) and metals (As, Pb, Ni, Cd and Hg). The more soluble constituents tend to migrate to adjacent areas with the groundwater flow and thereby reach receptors such as drinking water resources. Among the above pollutants, the 16 PAHs from the priority list of the Environmental Protection Agency (EPA) are of great environmental concern due to their toxic, mutagenic and carcinogenic properties. The remediation of PAH-polluted sites poses a crucial challenge given the large number of sites contaminated by these pollutants and the difficulty in eliminating the pollution. A better evaluation of the PAH transfer and transport in soils and aquifers will also help draw up remediation strategies. In this study, a numerical model, called SIMUSCOPP and developed by the French Petroleum Institute (IFP), BURGEAP and ENI group for organic pollutants, was used to simulate 3D transfer and

Review of quantitative surveys of the length and stability of MTBE, TBA, and benzene plumes in groundwater at UST sites.

Science.gov (United States)

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

2015-01-01

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. © 2014 GSI Environmental Inc. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

Comparative metabolism of [14C]benzene to excretable products and bioactivation to DNA-binding derivatives in maternal and neonatal mice

International Nuclear Information System (INIS)

Iba, M.M.; Ghosal, A.; Snyder, R.

2001-01-01

Lactating adult female mice treated with a single dose of 880 mg/kg i.p. [ 14 C]benzene, and their 2-day-old sucklings similarly treated or nursed by their treated dams were compared in terms of their ability to metabolize benzene to urinary products or reactive intermediates as assessed by covalently-bound benzene derivatives in whole blood or liver DNA. Six metabolite fractions were identified in the urine of sucklings by high performance liquid chromatographic (HPLC) analysis at 5 h following intraperitoneal (direct) treatment with benzene. Three of the metabolite fractions co-chromatographed with authentic phenol, phenyl glucuronide, and muconic acid, and contributed 11, 6.9 and 0.6%, respectively, to the total urinary benzene metabolites. Two of the fractions were unidentified. The sixth and most polar fraction consisted of multiple metabolites, 21% of which were conjugates, and accounted for 72% of the total urinary metabolites. A similar metabolite profile was observed in 24-h urine samples from treated dams with the exception that one of the unidentified fractions in the sucklings was absent and levels of the metabolites were quantitatively higher than those observed in sucklings 5 h following their treatment with benzene. Furthermore, 78% of the most polar fraction from the dams consisted of conjugates compared with 21% of that from the sucklings. The metabolite pattern in urine of sucklings nursed by treated dams was qualitatively similar to, but quantitatively different from the pattern in treated dams. Five hours following intraperitoneal treatment with benzene, covalent binding of the compound to DNA (expressed as pmol benzene equivalents/mg DNA) in sucklings was slightly higher in whole blood (1.15±0.07) than in liver (0.77±0.07), whereas in the dam, it was slightly lower in whole blood (0.88±0.48) than in liver (1.63±0.61). Twenty four hours following benzene exposure in sucklings of benzene-treated dams, DNA binding by the compound in whole

A system for the analysis of tritium content in natural waters, through benzene

International Nuclear Information System (INIS)

Bocchi, N.

1980-01-01

A system is described for the analysis of tritium ( 3 H) in natural waters. The system consists of an electrolytic enrichment equipment and a vacuum line for benzene synthesis. The benzene is mixed with a scintillating solution and so used in tritium activity measurements by liquid scintillation spectrometry. The characteristcs of the system, as well as its performance, are pointed out through analysis of ground and rain waters. The precision and reproducibility of the measurements are discussed. (Author) [pt

40 CFR 80.1334 - What are the requirements for early compliance with the gasoline benzene program?

Science.gov (United States)

2010-07-01

... compliance with the gasoline benzene program? 80.1334 Section 80.1334 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Hardship Provisions § 80.1334 What are the requirements for early compliance with the gasoline...

Isopropylation of benzene with 2-propanol over substituted large ...

Indian Academy of Sciences (India)

3. The major draw- back of these catalysts is their corrosive and envi- ronmentally hazardous ... catalytic activity towards vapor phase isopropylation of benzene with ... 2 cm i.d. The glass reactor was heated to the requi- site temperature with ...

Health Risk Assessment of Inhalation Exposure to Formaldehyde and Benzene in Newly Remodeled Buildings, Beijing

Science.gov (United States)

Huang, Lihui; Mo, Jinhan; Sundell, Jan; Fan, Zhihua; Zhang, Yinping

2013-01-01

Objective To assess health risks associated with inhalation exposure to formaldehyde and benzene mainly emitted from building and decoration materials in newly remodeled indoor spaces in Beijing. Methods We tested the formaldehyde and benzene concentrations in indoor air of 410 dwellings and 451 offices remodeled within the past year, in which the occupants had health concerns about indoor air quality. To assess non-carcinogenic health risks, we compared the data to the health guidelines in China and USA, respectively. To assess carcinogenic health risks, we first modeled indoor personal exposure to formaldehyde and benzene using the concentration data, and then estimated the associated cancer risks by multiplying the indoor personal exposure by the Inhalation Unit Risk values (IURs) provided by the U.S. EPA Integrated Risk Information System (U.S. EPA IRIS) and the California Office of Environmental Health Hazard Assessment (OEHHA), respectively. Results (1) The indoor formaldehyde concentrations of 85% dwellings and 67% offices were above the acute Reference Exposure Level (REL) recommended by the OEHHA and the concentrations of all tested buildings were above the chronic REL recommended by the OEHHA; (2) The indoor benzene concentrations of 12% dwellings and 32% offices exceeded the reference concentration (RfC) recommended by the U.S. EPA IRIS; (3) The median cancer risks from indoor exposure to formaldehyde and benzene were 1,150 and 106 per million (based on U.S. EPA IRIS IURs), 531 and 394 per million (based on OEHHA IURs). Conclusions In the tested buildings, formaldehyde exposure may pose acute and chronic non-carcinogenic health risks to the occupants, whereas benzene exposure may pose chronic non-carcinogenic risks to the occupants. Exposure to both compounds is associated with significant carcinogenic risks. Improvement in ventilation, establishment of volatile organic compounds (VOCs) emission labeling systems for decorating and refurbishing materials

Soluble FLT-1 rules placental destiny.

Science.gov (United States)

Yamashita, Michiko; Kumasawa, Keiichi; Nakamura, Hitomi; Kimura, Tadashi

2018-02-19

Placenta previa is an abnormality in which the placenta covers the internal uterine os, and it can cause serious morbidity and mortality in both mother and fetus due to catastrophic hemorrhage. Some pregnant women recover from placenta previa due to a phenomenon called "migration." However, the mechanism of "migration" of the placenta has not been elucidated. Human placentas were collected from patients with placenta previa and those with no abnormal placentation (control). A microarray analysis was performed to detect the genes up- or down-regulated only in the caudal part in the previa group. Specific mRNA expression was evaluated using real-time quantitative reverse transcription PCR (qRT-PCR). Unilateral uterine artery ablation of 8.5 dpc mice was performed to reproduce the reduction of placental blood supply, and weights of the placentas and fetuses were evaluated in 18.5 dpc. Specific mRNA expression was also evaluated in mice placentas. According to the result of the microarray analysis, we focused on soluble fms-like tyrosine kinase-1 (sFLT-1) and hypoxia-inducible factor-1 (HIF-1) alpha. The sFLT-1 expression level is locally high in the caudal part of the human placenta in patients with placenta previa. In mice experiments, the weights of the placentas and fetuses were significantly smaller in the ablation side than those in the control side, and the sFlt-1 expression level was significantly higher in the ablation side than in the control side. Our study suggests that "migration" of the placenta is derived from placental degeneration at the caudal part of the placenta, and sFlt-1 plays a role in this placental degeneration. Copyright © 2018 Elsevier Inc. All rights reserved.

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

DEFF Research Database (Denmark)

Rolle, Massimo; Jin, Biao

2017-01-01

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

Iron-functionalized Al-SBA-15 for benzene hydroxylation

NARCIS (Netherlands)

Li, Y.; Xia, H.; Fan, F.; Feng, Z.; Santen, van R.A.; Hensen, E.J.M.; Li, Can

2008-01-01

For the first time an ordered mesoporous silica (Fe–Al-SBA-15) with catalytically active isolated Fe surface species for the hydroxylation of benzene with nitrous oxide is prepared by introduction of Fe3+ in the synthesis gel of Al-SBA-15. Graphical abstract image for this article (ID: b717079c)

Sample preparation of environmental samples using benzene synthesis followed by high-performance LSC

International Nuclear Information System (INIS)

Filippis, S. De; Noakes, J.E.

1991-01-01

Liquid scintillation counting (LSC) techniques have been widely employed as the detection method for determining environmental levels of tritium and 14 C. Since anthropogenic and nonanthropogenic inputs to the environment are a concern, sampling the environment surrounding a nuclear power facility or fuel reprocessing operation requires the collection of many different sample types, including agriculture products, water, biota, aquatic life, soil, and vegetation. These sample types are not suitable for the direct detection of tritium of 14 C for liquid scintillation techniques. Each sample type must be initially prepared in order to obtain the carbon or hydrogen component of interest and present this in a chemical form that is compatible with common chemicals used in scintillation counting applications. Converting the sample of interest to chemically pure benzene as a sample preparation technique has been widely accepted for processing samples for radiocarbon age-dating applications. The synthesized benzene is composed of the carbon or hydrogen atoms from the original sample and is ideal as a solvent for LSC with excellent photo-optical properties. Benzene synthesis followed by low-background scintillation counting can be applied to the preparation and measurement of environmental samples yielding good detection sensitivities, high radionuclide counting efficiency, and shorter preparation time. The method of benzene synthesis provides a unique approach to the preparation of a wide variety of environmental sample types using similar chemistry for all samples

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

Science.gov (United States)

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

2007-08-01

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

Issues concerning the determination of solubility products of sparingly soluble crystalline solids. Solubility of HfO2(cr)

International Nuclear Information System (INIS)

Rai, Dhanpat; Kitamura, Akira; Rosso, Kevin M.; Sasaki, Takayuki; Kobayashi, Taishi

2016-01-01

Solubility studies were conducted with HfO 2 (cr) solid as a function HCl and ionic strength ranging from 2.0 to 0.004 mol kg -1 . These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 C, and (4) heating amorphous HfO 2 (am) suspensions to 90 C to ascertain whether the HfO 2 (am) converts to HfO 2 (cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO 2 (cr) contains a small fraction of less crystalline, but not amorphous, material [HfO 2 (lcr)] and this, rather than the HfO 2 (cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models and they provide log 10 K 0 values of -(59.75±0.35) and -(59.48±0.41), respectively, for the solubility product of HfO 2 (lcr)[HfO 2 (lcr) + 2H 2 O ↔ Hf 4+ + 4OH - ]. The log 10 of the solubility product of HfO 2 (cr) is estimated to be < -63. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or compositionally imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

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

Energy Technology Data Exchange (ETDEWEB)

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

2004-07-01

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

Numerical examination of the factors controlling DNAPL migration through a single fracture.

Science.gov (United States)

Reynolds, D A; Kueper, B H

2002-01-01

The migration of five dense nonaqueous phase liquids (DNAPLs) through a single fracture in a clay aquitard was numerically simulated with the use of a compositional simulator. The effects of fracture aperture, fracture dip, matrix porosity, and matrix organic carbon content on the migration of chlorobenzene, 1,2-dichloroethylene, trichloroethylene, tetra-chloroethylene, and 1,2-dibromoethane were examined. Boundary conditions were chosen such that DNAPL entry into the system was allowed to vary according to the stresses applied. The aperture is the most important factor of those studied controlling the migration rate of DNAPL through a single fracture embedded in a clay matrix. Loss of mass to the matrix through diffusion does not significantly retard the migration rate of the DNAPL, particularly in larger aperture fractures (e.g., 50 microm). With time, the ratio of diffusive loss to the matrix to DNAPL flux into the fracture approaches an asymptotic value lower than unity. The implication is that matrix diffusion cannot arrest the migration of DNAPL in a single fracture. The complex relationships between density, viscosity, and solubility that, to some extent, govern the migration of DNAPL through these systems prevent accurate predictions without the use of numerical models. The contamination potential of the migrating DNAPL is significantly increased through the transfer of mass to the matrix. The occurrence of opposite concentration gradients within the matrix can cause dissolved phase contamination to exist in the system for more than 1000 years after the DNAPL has been completely removed from the fracture.

Aerobic Biodegradation Characteristic of Different Water-Soluble Azo Dyes

Directory of Open Access Journals (Sweden)

Shixiong Sheng

2017-12-01

Full Text Available This study investigated the biodegradation performance and characteristics of Sudan I and Acid Orange 7 (AO7 to improve the biological dye removal efficiency in wastewater and optimize the treatment process. The dyes with different water-solubility and similar molecular structure were biologically treated under aerobic condition in parallel continuous-flow mixed stirred reactors. The biophase analysis using microscopic examination suggested that the removal process of the two azo dyes is different. Removal of Sudan I was through biosorption, since it easily assembled and adsorbed on the surface of zoogloea due to its insolubility, while AO7 was biodegraded incompletely and bioconverted, the AO7 molecule was decomposed to benzene series and inorganic ions, since it could reach the interior area of zoogloea due to the low oxidation-reduction potential conditions and corresponding anaerobic microorganisms. The transformation of NH3-N, SO42− together with the presence of tryptophan-like components confirm that AO7 can be decomposed to non-toxic products in an aerobic bioreactor. This study provides a theoretical basis for the use of biosorption or biodegradation mechanisms for the treatment of different azo dyes in wastewater.

Conversion of straight-run gas-condensate benzenes into high- octane gasolines based on modified ZSM-5 zeolites

International Nuclear Information System (INIS)

Erofeev, V; Reschetilowski, V; Khomajakov, I; Egorova, L; Volgina, T; Tatarkina, A

2014-01-01

This paper describes the conversion of straight-run benzene of gas condensate into high-octane gasoline based on zeolite catalyst ZSM-5, modified in binary system oxide- based Sn (III) and Bi (III). It was defined that the introduction of the binary system oxide-based Sn(III) and Bi (III) into the basic zeolite results in the 2-fold increase of its catalytic activity.High-octane gasoline converted from straight-run benzene is characterized by a low benzol content in comparison to the high-octane benzenes produced during the catalytic reforming

Metabolic Polymorphisms and Clinical Findings Related to Benzene Poisoning Detected in Exposed Brazilian Gas-Station Workers

Directory of Open Access Journals (Sweden)

Simone Mitri

2015-07-01

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.

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

Science.gov (United States)

Jia, L.; Xu, Y.

2012-12-01

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

A new certified reference material for benzene measurement in air on a sorbent tube: development and proficiency testing

Energy Technology Data Exchange (ETDEWEB)

Caurant, A. [Laboratoire National de Metrologie et d' Essais, Paris (France); Universite Paris 12 et CNRS (UMR 7583), Faculte des Sciences et Technologie, Laboratoire Inter-universitaire des Systemes Atmospheriques, Unite Mixte de Recherche Universite Paris 7 (France); Lalere, B.; Schbath, M.C.; Stumpf, C.; Sutour, C.; Mace, T.; Vaslin-Reimann, S. [Laboratoire National de Metrologie et d' Essais, Paris (France); Quisefit, J.P.; Doussin, J.F. [Universite Paris 12 et CNRS (UMR 7583), Faculte des Sciences et Technologie, Laboratoire Inter-universitaire des Systemes Atmospheriques, Unite Mixte de Recherche Universite Paris 7 (France)

2010-11-15

A certified matrix reference material (CRM) for the measurement of benzene in ambient air has been developed at Laboratoire National de Metrologie 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 trademark 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. (orig.)

Fully coupled modeling of radionuclide migration in a clayey rock disturbed by alkaline plume

International Nuclear Information System (INIS)

Pellegrni, D.; Windt, L. de; Lee, J.V.D.

2002-03-01

The disposal of radioactive wastes in clayey formations may require the use of large amounts of concrete and cement as a barrier to minimize corrosion of steel containers and radionuclide migration and for supporting drifts and disposal vaults. In this context, reactive transport modeling of the interactions between cement or concrete and the argillaceous host rock aims at estimating the evolution in time of the containment properties of the multi-barriers system. The objectives of the paper are to demonstrate that integrating radionuclides migration in the modeling of strongly coupled geochemical processes of cement-clay stone interactions is feasible and that it represents an efficient way to assess the sensitivity and modification of the classical Kd and solubility parameters with respect to the chemical evolutions. Two types of modeling are considered in the paper: i): calculation of intrinsic solubility limits and Kd values backing up on the results of modeling of cement/clay stone interactions (radionuclides are assumed to be present over the whole domain at any time whatever the scenario), ii) full mechanistic modeling which explicitly introduces radionuclides in the calculation with ad hoc assumptions on radionuclide inventory, canister failure, migration pathway, etc. The reactive transport code HYTEC, based on the geochemical code CHESS, is used to simulate both the cement-clay stone interaction processes and the radionuclide migration in 1-D and 2-D configurations. Convective/dispersive and diffuse transport can be simulated for solutes and colloids. A wide range of processes such as aqueous chemistry, redox, dissolution/precipitation, surface complexation and ion exchange can be modeled at equilibrium or with kinetic control. In addition, HYTEC is strongly coupled, i.e. the hydrology (flow and diffusion) may change when mineral precipitation or dissolution changes the local porosity. (authors)

Δg: The new aromaticity index based on g-factor calculation applied for polycyclic benzene rings

Science.gov (United States)

Ucun, Fatih; Tokatlı, Ahmet

2015-02-01

In this work, the aromaticity of polycyclic benzene rings was evaluated by the calculation of g-factor for a hydrogen placed perpendicularly at geometrical center of related ring plane at a distance of 1.2 Å. The results have compared with the other commonly used aromatic indices, such as HOMA, NICSs, PDI, FLU, MCI, CTED and, generally been found to be in agreement with them. So, it was proposed that the calculation of the average g-factor as Δg could be applied to study the aromaticity of polycyclic benzene rings without any restriction in the number of benzene rings as a new magnetic-based aromaticity index.

Organosulfur chemistry on W(211) surfaces. 2. A comparison of benzene, thiophene, and tetrahydrothiophene

International Nuclear Information System (INIS)

Preston, R.E.; Benziger, J.B.

1985-01-01

The interactions of benzene, thiophene, and tetrahydrothiophene with clean, oxidized, and sulfided W(211) surfaces were studied with LEED, AES, and temperature programmed reaction. Benzene and thiophene appear to absorb as bases making π-bonds to the surface. Benzene decomposed to yield adsorbed carbon and hydrogen. Thiophene appeared to undergo electrophilic attack at the 2-position forming a carbon bound surface intermediate. This surface intermediate was desulfurized and the resulting hydrocarbon surface intermediate underwent C-C bond scission forming C 3 hydrocarbons as the dominate desorption product. The electrophilic attack at the 2-position was shown by methyl group elimination from 2,5-dimethylthiophene. Adsorbed oxygen and sulfur enhanced the adsorption of benzene and thiophene by making the surface more acidic. Tetrahydrothiophene (THT) appear to adsorb as a base, forming a bond between the S(3p) electrons and the surface. Desulfurization of adsorbed THT led to C 4 hydrocarbons as the dominate desorption product. Adsorbed oxygen and sulfur inhibited reaction of THT. These results suggest that the surface reactivity and subsequent desulfurization of thiophene is controlled by electrophilic attack on the aromatic ring, and the ensuing reduction of resonance stabilization facilitates sulfur removal. 41 references, 8 figures, 4 tables

Solvation of decane and benzene in mixtures of 1-octanol and N, N-dimethylformamide

Science.gov (United States)

Kustov, A. V.; Smirnova, N. L.

2016-09-01

The heats of dissolution of decane and benzene in a model system of octanol-1 (OctOH) and N, N-dimethylformamide (DMF) at 308 K are measured using a variable temperature calorimeter equipped with an isothermal shell. Standard enthalpies are determined and standard heat capacities of dissolution in the temperature range of 298-318 K are calculated using data obtained in [1, 2]. The state of hydrocarbon molecules in a binary mixture is studied in terms of the enhanced coordination model (ECM). Benzene is shown to be preferentially solvated by DMF over the range of physiological temperatures. The solvation shell of decane is found to be strongly enriched with 1-octanol. It is obvious that although both hydrocarbons are nonpolar, the presence of the aromatic π-system in benzene leads to drastic differences in their solvation in a lipid-protein medium.

Formation of a bioconjugate composed of hemin, smectite, and quaternary ammonium chloride that is soluble and active in hydrophobic media.

Science.gov (United States)

Kurosawa, Masaru; Itoh, Tetsuji; Kodera, Yoh; Matsushima, Ayako; Hiroto, Misao; Nishimura, Hiroyuki; Inada, Yuji

2002-01-01

Hemin (Fe(3+)) was adsorbed onto synthetic smectite (clay mineral) intercalated with a quaternary alkenylammonium compound, dioleyldimethylammonium chloride (DOA), to form a hemin-smectite-DOA conjugate. The hemin-smectite-DOA conjugate was soluble in organic solvents such as benzene and toluene to form a transparent colloidal solution with a light yellow color. Its absorption spectrum in benzene showed two bands, 600 and 568 nm, in the visible region and a sharp Soret band at 400 nm with the molar extinction coefficient of 7.5 x 10(4) M(-1) cm(-1). The formation of the conjugate of smectite and DOA was confirmed by X-ray diffraction analysis: the basal spacing, d(001), of hemin-smectite-DOA conjugate was 19 A which is an expansion of the interlayer space by 5 A based upon the basal spacing of smectite of 14 A. Hemin-smectite-DOA conjugate catalyzed the peroxidase-like reaction in organic solvents using benzoyl peroxide as the hydrogen acceptor and leucocrystal violet as the hydrogen donor. The temperature-dependent peroxidase-like activity of the conjugate was compared with peroxidase activity of horseradish peroxidase. The hemin-smectite-DOA conjugate exhibited higher activity as the temperature was increased from 30 to 70 degrees C, while horseradish peroxidase activity was reduced as the temperature was increased.

Outline and operations of benzene plant

Energy Technology Data Exchange (ETDEWEB)

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

1983-01-01

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

Poly[di-μ4-benzene-1,4-dicarboxylato-μ6-succinato-diholmium(III

Directory of Open Access Journals (Sweden)

Qin He

2008-01-01

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.

Influence of sample temperature and environmental humidity on measurements of benzene in ambient air by transportable GC-PID

Directory of Open Access Journals (Sweden)

C. Romero-Trigueros

2017-10-01

Full Text Available Calibration of in situ analysers of air pollutants is usually done with dry standards. In this paper, the influence of sample temperature and environmental humidity on benzene measurements by gas chromatography coupled with a photoionisation detector (GC-PID is studied. Two reference gas mixtures (40 and 5 µg m−3 nominal concentration benzene in air were subjected to two temperature cycles (20/5/20 °C and 20/35/20 °C and measured with two identical GC-PIDs. The change in sample temperature did not produce any significant change in readings. Regarding ambient humidity, the chromatographs were calibrated for benzene with dry gases and subjected to measure reference standards with humidity (20 and 80 % at 20 °C. When measuring a concentration of 0.5 µg m−3 benzene in air, the levels of humidity tested did not produce any significant interference in measurements taken with any of the analysers. However, when measuring a concentration of 40 µg m−3, biases in measurements of 18 and 21 % for each respective analyser were obtained when the relative humidity of the sample was 80 % at 20 °C. Further tests were carried out to study the nature of this interference. Results show that humidity interference depends on both the amount fractions of water vapour and benzene. If benzene concentrations in an area are close to its annual limit value (5 µg m−3, biases of 2.2 % can be expected when the absolute humidity is 8.6 g cm−3 – corresponding to a relative humidity of 50 % at 20 °C. This can be accounted for in the uncertainty budget of measurements with no need for corrections. If benzene concentrations are above the annual limit value, biases become higher. Thus, in these cases, actions should be taken to reduce the humidity interference, as an underestimation of benzene concentrations may cause a mismanagement of air quality in these situations.

Effect of halogenated benzenes on acetanilide esterase, acetanilide hydroxylase and procaine esterase in rats.

Science.gov (United States)

Carlson, G P; Dziezak, J D; Johnson, K M

1979-07-01

1,2,4-Trichlorobenzene, 1,3,5-trichlorobenzene, hexachlorobenzene, 1,2,4-tribromobenzene, 1,3,5-tribromobenzene and hexabromobenzene were compared for their abilities to induce acetanilide esterase, acentailide hydroxylase and procaine esterase. Except for hexabromobenzene all induced acetanilide esterase whereas the hydroxylation of acetanilide was seen only with the fully halogenated benzenes and with 1,3,5-tribromobenzene. Hepatic procaine esterase activity was increased by the three chlorinated benzenes and 1,2,4-tribromobenzene.

First evidence of a water-soluble plutonium(IV) hexanuclear cluster

Energy Technology Data Exchange (ETDEWEB)

Tamain, Christelle; Dumas, Thomas; Guillaumont, Dominique; Guilbaud, Philippe [CEA, Nuclear Energy Division, Marcoule, RadioChemistry and Processes Department, Bagnols sur Ceze (France); Hennig, Christoph [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Dresden (Germany)

2016-08-15

The singular Pu{sup IV} hexanuclear cluster [Pu{sub 6}(OH){sub 4}O{sub 4}]{sup 12+} stabilized by 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) ligands was structurally characterized for the first time both in the solid state and in water solution by using X-ray diffraction and X-ray absorption and UV/Vis spectroscopy. The stability of this cluster in water and its high solubility over a large pH range are of upmost importance for plutonium environmental speciation with potential applications in a related migration model. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Estimating Benzene Exposure Level over Time and by Industry Type through a Review of Literature on Korea.

Science.gov (United States)

Park, Donguk; Choi, Sangjun; Ha, Kwonchul; Jung, Hyejung; Yoon, Chungsik; Koh, Dong-Hee; Ryu, Seunghun; Kim, Soogeun; Kang, Dongmug; Yoo, Kyemook

2015-09-01

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980-1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990-1994 period, and to 0.1 ppm (n = 294) in the 1995-1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005-2009 period and 4.5 ppm (n = 3,358) for the 2010-2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

Issues concerning the determination of solubility products of sparingly soluble crystalline solids. Solubility of HfO{sub 2}(cr)

Energy Technology Data Exchange (ETDEWEB)

Rai, Dhanpat [Rai Enviro-Chem, LLC, Yachats, OR (United States); Kitamura, Akira [Japan Atomic Energy Agency, Ibaraki (Japan); Rosso, Kevin M. [Pacific Northwest National Laboratory, Richland, WA (United States); Sasaki, Takayuki; Kobayashi, Taishi [Kyoto Univ. (Japan)

2016-11-01

Solubility studies were conducted with HfO{sub 2}(cr) solid as a function HCl and ionic strength ranging from 2.0 to 0.004 mol kg{sup -1}. These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 C, and (4) heating amorphous HfO{sub 2}(am) suspensions to 90 C to ascertain whether the HfO{sub 2}(am) converts to HfO{sub 2}(cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO{sub 2}(cr) contains a small fraction of less crystalline, but not amorphous, material [HfO{sub 2}(lcr)] and this, rather than the HfO{sub 2}(cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models and they provide log{sub 10} K{sup 0} values of -(59.75±0.35) and -(59.48±0.41), respectively, for the solubility product of HfO{sub 2}(lcr)[HfO{sub 2}(lcr) + 2H{sub 2}O ↔ Hf{sup 4+} + 4OH{sup -}]. The log{sub 10} of the solubility product of HfO{sub 2}(cr) is estimated to be < -63. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or compositionally imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

PLACENTAL SECRETORY FACTORS INFLUENCE TO THP-1 CELLS PHENOTYPE AND THP-1 CELLS TRANSENDOTHELIAL MIGRATION

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O. I. Stepanova

2013-01-01

Full Text Available Decidual and placental macrophage pools are renewed due to its transendothelial monocyte migration from peripheral blood. Tissue macrophages control placental development and provide fetomaternal immunological tolerance. Preeclamptic pregnancy is accompanied by increased monocyte migration to decidual tissue and local inflammatory events. Regulatory mechanisms of monocyte recruitment to placental and decidual tissues is still unclear. Therefore we investigated the influence soluble placental factors (SPFs during the first- and third-trimester normal pregnancy, as compared to effects of these factors in preeclamptic pregnancy. We studied biological actions of SPF upon transendothelial migration of monocyte-like THP-1 cells and their phenotypic pattern. Transendothelial migration of THP-1 cells was more intensive with firsttrimester SPFs from normal pregnancy, when compared with third-trimester samples, and it was accompanied by decreased CD11a expression. SPFs from pre-eclamptic pregnancy caused an increase in transendothelial migration of THP-1 cells, as compared to SPFs from normal pregnancies, being accompanied by increased CD11b expression. The present study was supported by grants ГК №  02.740.11.0711, НШ-3594.2010.7, МД-150.2011.7 and a grant from St.-Petersburg Goverment for young scientists.

SELENIUM EFFECT UPON THE RATS' HEMATOPOIESIS IN THE SUBACUTE BENZENE INTOXICATION

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Pavle Randjelovic

2001-03-01

Full Text Available The antioxidants (selenium, vitamins C and E stabilize the cell membrane andprotect the cells from the action of free radicals. On the other hand, the antioxidantsreduce the effects of chemical and physical agenls. Bcsidcs, selenium has animportant role in Transporting electrons in the mitochondria and il is necessary for iheglulathione peroxidase function in the protection from apoplhosis. Benzene is auniversal solvent and has a wide application in chemical industry. Its toxicity ismanifested in the damages done to the central nervous syslem, liver, kidneys andhematopoiesis system. Tn this experiment the Wistar rats were used that wereclassified in three experimental groups regarding the quantity of the receivedselenium. Each group comprised ten animals of both sexes and after two weeks'treatment by selenium of 4,8 and 16 mcg, the animals had received benzene byinlraperiloneal administration in the dose of 1,2 ml/kg of the body weight. Thecounting of the shaped blood elements was done after the selenium pretreatment andafter the benzene intoxication. The obtained results poinl to increased number of alithe blood elements after the selenium pretreatment while after benzene adminislrationthere was a drastic drop of the number of erylhrocyles and leukocytes alongwith moderate lhrombocylopenia. After the sacrifice, Ihe hematopoiesis organs weretaken. The hislological findings of the bone marrow show the emergence ofdisturbances, especially of the red sort cells as well as an obvious fat degeneration which is particularly conspicuous in the second and third groups of animals. Therewas also some damage done to the spleen, especially of its red pulp along with thepresence of a greater number of fresh erythrocytes in the second and third groups.Only the changes were more drastic in the third group. The obtained results show thatselenium in higher concentrations increases the number of erytrocytes andleukocytes which proves that it stimulates highly

Color-tunable and high-efficiency organic light-emitting diode by adjusting exciton bilateral migration zone

Science.gov (United States)

Liu, Shengqiang; Wu, Ruofan; Huang, Jiang; Yu, Junsheng

2013-09-01

A voltage-controlled color-tunable and high-efficiency organic light-emitting diode (OLED) by inserting 16-nm N,N'-dicarbazolyl-3,5-benzene (mCP) interlayer between two complementary emitting layers (EMLs) was fabricated. The OLED emitted multicolor ranging from blue (77.4 cd/A @ 6 V), white (70.4 cd/A @ 7 V), to yellow (33.7 cd/A @ 9 V) with voltage variation. An equivalent model was proposed to reveal the color-tunable and high-efficiency emission of OLEDs, resulting from the swing of exciton bilateral migration zone near mCP/blue-EML interface. Also, the model was verified with a theoretical arithmetic using single-EML OLEDs to disclose the crucial role of mCP exciton adjusting layer.

Thoracic empyema and pectoral abscess resulting from attempting suicide by injection of benzene in the pleural cavity

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Sjaak Pouwels

Full Text Available Background: Exposure to hydrocarbon compounds, such as benzene may cause injury to several organ systems. It occurs accidentally or intentionally by ingestion, inhalation, cutaneous exposure and either subcutaneous injection or intravenous injection. We report a patient who injected benzene into the left hemithorax and secondly attempted to commit suicide with paracetamol. Case presentation: A 52-year old man was admitted in the hospital because of an attempted suicide with an injection of benzene in the left hemithorax and ingestion of 50 tablets of 500 mg paracetamol. He developed a hydro-tensionpneumothorax due to inflammatory pleural effusion as a reaction to intrathoracic benzene. Therefore a chest-tube was inserted. A few days later he developed an empyema in the left lung and secondly a pectoral abscess, which required surgical debridement. After surgery, recovered fully and after 23 days of hospitalisation he was discharged to a psychiatric care facility. Conclusion: Hydrocarbon poisoning is either accidentally or intentionally and leads to thoracic pathology in rare cases. The most affected organ system is the respiratory system, and the cytotoxic effects of hydrocarbons can manifest as respiratory failure, pneumonitis and even acute respiratory distress syndrome (ARDS. Keywords: Benzene intoxication, Thoracic empyema, Hydrocarbon poisoning

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)

2005-07-01

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)

Exciton Migration and Amplified Quenching on Two-Dimensional Metal–Organic Layers

Energy Technology Data Exchange (ETDEWEB)

Cao, Lingyun; Lin, Zekai; Shi, Wenjie; Wang, Zi; Zhang, Cankun; Hu, Xuefu; Wang, Cheng; Lin, Wenbin (UC); (Xiamen)

2017-05-10

The dimensionality dependency of resonance energy transfer is of great interest due to its importance in understanding energy transfer on cell membranes and in low-dimension nanostructures. Light harvesting two-dimensional metal–organic layers (2D-MOLs) and three-dimensional metal–organic frameworks (3D-MOFs) provide comparative models to study such dimensionality dependence with molecular accuracy. Here we report the construction of 2D-MOLs and 3D-MOFs from a donor ligand 4,4',4''-(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tribenzoate (BTE) and a doped acceptor ligand 3,3',3''-nitro-4,4',4''-(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tribenzoate (BTE-NO2). These 2D-MOLs and 3D-MOFs are connected by similar hafnium clusters, with key differences in the topology and dimensionality of the metal–ligand connection. Energy transfer from donors to acceptors through the 2D-MOL or 3D-MOF skeletons is revealed by measuring and modeling the fluorescence quenching of the donors. We found that energy transfer in 3D-MOFs is more efficient than that in 2D-MOLs, but excitons on 2D-MOLs are more accessible to external quenchers as compared with those in 3D-MOFs. These results not only provide support to theoretical analysis of energy transfer in low dimensions, but also present opportunities to use efficient exciton migration in 2D materials for light-harvesting and fluorescence sensing.

4-Methyl-N-(1-methyl-1H-indazol-5-yl)benzene­sulfonamide

Science.gov (United States)

Chicha, Hakima; Oulemda, Bassou; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C15H15N3O2S, the fused ring system is close to planar, the largest deviation from the mean plane being 0.030 (2) Å, and makes a dihedral angle of 48.84 (9)° with the benzene ring belonging to the methyl­benzene­sulfonamide moiety. In the crystal, mol­ecules are ­connected through N—H⋯N hydrogen bonds and weak C—H⋯O contacts, forming a two-dimensional network parallel to (001). PMID:24427093

Isopropylation of benzene with 2-propanol over substituted large ...

Indian Academy of Sciences (India)

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%) ...

Using 13C-labeled benzene and Raman gas spectroscopy to investigate respiration and biodegradation kinetics following soil contamination

Science.gov (United States)

Jochum, Tobias; Popp, Juergen; Frosch, Torsten

2016-04-01

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.

Sensitive and selective system of benzene detection based on a cataluminescence sensor.

Science.gov (United States)

Li, Bo; Zhang, Yuejin; Liu, Juefu; Xie, Xin; Zou, Dan; Li, Minqiang; Liu, Jinhuai

2014-06-01

Au/La2 O3 nanomaterials were prepared through calcining Au-modified La(OH)3 precursors. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD) were employed to characterize the as-prepared samples. Benzene, a common volatile organic compound, was selected as a model to investigate the cataluminescence (CTL)-sensing properties of the Au/La2 O3 nanomaterials. Results indicated that the as-prepared Au/La2 O3 exhibited outstanding CTL properties such as stable intensity, high signal-to-noise values, and short response and recovery times. Under optimized conditions, the benzene assay exhibited a broad linear range of 1-4000 ppm, with a limit of detection of 0.7 ppm, which was below the standard permitted concentrations. Furthermore, the gas sensor system showed outstanding selectivity for benzene compared with seven other types of common volatile organic compounds (VOCs). The proposed gas sensor showed good characteristics with high selectivity, fast response time and long lifetime, which suggested the promising application of the Au/La2 O3 nanomaterials as a novel highly efficient CTL-sensing material. Copyright © 2013 John Wiley & Sons, Ltd.

Gas solubilities widespread applications

CERN Document Server

Gerrard, William

1980-01-01

Gas Solubilities: Widespread Applications discusses several topics concerning the various applications of gas solubilities. The first chapter of the book reviews Henr's law, while the second chapter covers the effect of temperature on gas solubility. The third chapter discusses the various gases used by Horiuti, and the following chapters evaluate the data on sulfur dioxide, chlorine data, and solubility data for hydrogen sulfide. Chapter 7 concerns itself with solubility of radon, thoron, and actinon. Chapter 8 tackles the solubilities of diborane and the gaseous hydrides of groups IV, V, and

SYNTHESIS AND PHYSICAL-CHEMICAL PROPERTIES OF WATER-SOLUBLE 3-BENZYLXANTHINE DERIVATIVES

Directory of Open Access Journals (Sweden)

K. V. Аleksandrova

2015-04-01

Full Text Available Introduction Nowadays, research of novel biological active compounds with low toxicity, are carried out among different classes of organic compounds of natural and synthetic genesis. One of the main ways of these studies is search of water-soluble compounds – convenient objects for pharmacological researches. In recent years researchers paid attention to xanthine derivatives, because of their high variativity of possible chemical modification and ability to form different salts with wide spectrum of biological action. Thus, among water-soluble xanthine derivatives were found compounds with pronounced antioxidant, diuretic and analeptic properties. Primary methods of obtaining water-soluble xanthine derivatives are direct interaction of bases with xanthine molecule or insertion basic or acidic residues in positions 7 or 8 of xanthine bicycle. According from the above, search of biologically active compounds among water-soluble substituted xanthines is prospective and actual. The aim of the study was development of synthetic ways of obtaining novel water-soluble derivatives of 3-benzyl-8-methylxanthine and studying their physical and chemical properties. Material and methods Melting points of obtained compounds were determined by capillary method on PTP (M device. ІR-spectra of synthesized compounds were recorded on the Bruker Alpha device (company «Bruker» – Germany on 4000-400 sm-1 with using console ATR (direct insertion of compound. 1Н NMR-spectra were recorded on the Varian Mercury VX-200 device (company «Varian» – USA solvent – (DMSO-d6, internal standart – ТМС. Elemental analysis was made on Elementar Vario L cube device. Chromatoraphic studies were made on the plates Sorbfil-AFV-UV (company «Sobrpolimer» –Russia. Systhems for chromatography: «acetone-propanol-2» in ratio 2:3, «propanol-2-benzene» in ratio 10:1 and exersized in UV-light in wave 200-300 nm. Results and discussion We developed methodic of synthesis

Theoretical investigation on the interaction between beryllium, magnesium and calcium with benzene, coronene, cirumcoronene and graphene

Energy Technology Data Exchange (ETDEWEB)

Denis, Pablo A., E-mail: pablod@fq.edu.uy; Iribarne, Federico

2014-02-17

Graphical abstract: - Highlights: • The binding energies between benzene and Be, Mg and Ca are 1.8, 2.3 and 3.2 kcal/mol. • The alkaline earth complexes with benzene favor the non ionic configuration. • For these complexes charge transfer does not take place. • The performance of the DFT functionals assayed was poor. - Abstract: The interaction energies (IE) between benzene and beryllium, magnesium and calcium were calculated at the CCSD(T)/CBS level and including corrections for core-valence and relativistic effects. The IE are 1.8, 2.3 and 3.2 kcal/mol for Be, Mg and Ca, respectively, In contrast with our previous findings for the benzene–Li complex, we found that the non-ionic structure is more stable than the ionic configuration. Thus, charge-transfer from alkaline earths to benzene would not take place. The performance of MP2 and DFT functionals is poor. At the complete basis set limit, M06-2X, M06-L, B97D and MP2 exhibited similar MAD (∼ 0.7–0.8 kcal/mol). When larger aromatic models were considered, the IE were similar to those computed for benzene. Finally, taking into account the drawbacks of the DFT functionals, the computed IE for the non-ionic adsorption of Be, Mg and Ca onto graphene, are tentatively estimated as 2.1, 2.7 and 2.9 kcal/mol, respectively.

Tritium-labeled (E,E)-2,5-Bis(4’-hydroxy-3’-carboxystyryl)benzene as a Probe for β-Amyloid Fibrils

Science.gov (United States)

Matveev, Sergey V.; Kwiatkowski, Stefan; Sviripa, Vitaliy M.; Fazio, Robert C.; Watt, David S.; LeVine, Harry

2014-01-01

Accumulation of Aβ in the brains of Alzheimer disease (AD) patients reflects an imbalance between Aβ production and clearance from their brains. Alternative cleavage of amyloid precursor protein (APP) by processing proteases generates soluble APP fragments including the neurotoxic amyloid Aβ40 and Aβ42 peptides that assemble into fibrils and form plaques. Plaque-buildup occurs over an extended time-frame, and the early detection and modulation of plaque formation are areas of active research. Radiolabeled probes for the detection of amyloid plaques and fibrils in living subjects are important for noninvasive evaluation of AD diagnosis, progression, and differentiation of AD from other neurodegenerative diseases and age-related cognitive decline. Tritium-labeled (E,E)-1-[3H]-2,5-bis(4’-hydroxy-3’-carbomethoxystyryl)benzene possesses an improved level of chemical stability relative to a previously reported radioiodinated analog for radiometric quantification of Aβ plaque and tau pathology in brain tissue and in vitro studies with synthetic Aβ and tau fibrils. PMID:25452000

The aqueous solubility and speciation analysis for uranium, neptunium and selenium by the geochemical code(EQ3/6)

International Nuclear Information System (INIS)

Takeda, Seiji; Shima, Shigeki; Kimura, Hideo; Matsuzuru, Hideo

1995-11-01

The geochemical condition of a geologic disposal system of HLW controls the solubility and physicochemical forms of dominant aqueous species for elements, which are one of essential information required for safety assessment. Based on the measured compositions of groundwater, the compositions of groundwater in the disposal system were calculated. The solubility and speciation analyses for the polyvalent elements, uranium, neptunium, and selenium, were performed by the geochemical code EQ3/6. The results obtained were compared with the data appeared in the literatures on the solubilities and speciations. The geochemical behaviors of the elements with respect to the solubility and speciation could quantitatively be elucidated for the compositions of the interstitial waters in an engineered barrier and ground water in a natural barrier. In the pH range of neutral to alkali, the solubilities of U and Np tend to increase with an increase of the carbonate concentration in groundwater. This carbonate concentration dependence of the solubility was also estimated. In the engineered barrier the predominant aqueous species were specified, and in the natural barrier the change of aqueous species was also predicted while the chemical compositions changed from the reducing to oxidizing conditions. The dominant aqueous species for the elements, which migrate in and through the disposal system, were determined by the speciation analysis. (author)

Estimating Benzene Exposure Level over Time and by Industry Type through a Review of Literature on Korea

Directory of Open Access Journals (Sweden)

Donguk Park

2015-09-01

Full Text Available The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980–1984 period of 50.4 ppm (n = 2,289, which dropped to 2.8 ppm (n = 305 in the 1990–1994 period, and to 0.1 ppm (n = 294 in the 1995–1999 period. There has been no improvement since the 2000s, when the AM(w of 4.3 ppm (n = 6,211 for the 2005–2009 period and 4.5 ppm (n = 3,358 for the 2010–2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

Degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria

NARCIS (Netherlands)

Weelink, S.A.B.

2008-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2002-08-01

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

Geochemistry and radionuclide migration

International Nuclear Information System (INIS)

Isherwood, D.

1978-01-01

Theoretically, the geochemical barrier can provide a major line of defense in protecting the biosphere from the hazards of nuclear waste. The most likely processes involved are easily identified. Preliminary investigations using computer modeling techniques suggest that retardation is an effective control on radionuclide concentrations. Ion exchange reactions slow radionuclide migration and allow more time for radioactive decay and dispersion. For some radionuclides, solubility alone may limit concentrations to less than the maximum permissible now considered acceptable by the Federal Government. The effectiveness of the geochemical barrier is ultimately related to the repository site characteristics. Theory alone tells us that geochemical controls will be most efficient in an environment that provides for maximum ion exchange and the precipitation of insoluble compounds. In site selection, consideration should be given to rock barriers with high ion exchange capacity that might also act as semi-permeable membranes. Also important in evaluating the site's potential for effective geochemical controls are the oxidation potentials, pH and salinity of the groundwater

Does borazine–water behave like benzene-water? A matrix isolation infrared and ab initio study

Energy Technology Data Exchange (ETDEWEB)

Mishra, P. [Department of Chemistry, Indian Institute of Science Education and Research, Sector 81, Mohali, Punjab 140306 (India); Purdue University, West Lafayette, Indiana 47907 (United States); Verma, K.; Bawari, D.; Viswanathan, K. S., E-mail: vish@iisermohali.ac.in [Department of Chemistry, Indian Institute of Science Education and Research, Sector 81, Mohali, Punjab 140306 (India)

2016-06-21

Borazine is isoelectronic with benzene and is popularly referred to as inorganic benzene. The study of non-covalent interactions with borazine and comparison with its organic counterpart promises to show interesting similarities and differences. The motivation of the present study of the borazine-water interaction, for the first time, stems from such interesting possibilities. Hydrogen-bonded complexes of borazine and water were studied using matrix isolation infrared spectroscopy and quantum chemical calculations. Computations were performed at M06-2X and MP2 levels of theory using 6-311++G(d,p) and aug-cc-pVDZ basis sets. At both the levels of theory, the complex involving an N–H⋯O interaction, where the N–H of borazine serves as the proton donor to the oxygen of water was found to be the global minimum, in contrast to the benzene-water system, which showed an H–π interaction. The experimentally observed infrared spectra of the complexes corroborated well with our computations for the complex corresponding to the global minimum. In addition to the global minimum, our computations also located two local minima on the borazine-water potential energy surface. Of the two local minima, one corresponded to a structure where the water was the proton donor to the nitrogen of borazine, approaching the borazine ring from above the plane of the ring; a structure that resembled the global minimum in the benzene-water H–π complex. The second local minimum corresponded to an interaction of the oxygen of water with the boron of borazine, which can be termed as the boron bond. Clearly the borazine-water system presents a richer landscape than the benzene-water system.

Does borazine–water behave like benzene-water? A matrix isolation infrared and ab initio study

International Nuclear Information System (INIS)

Mishra, P.; Verma, K.; Bawari, D.; Viswanathan, K. S.

2016-01-01

Borazine is isoelectronic with benzene and is popularly referred to as inorganic benzene. The study of non-covalent interactions with borazine and comparison with its organic counterpart promises to show interesting similarities and differences. The motivation of the present study of the borazine-water interaction, for the first time, stems from such interesting possibilities. Hydrogen-bonded complexes of borazine and water were studied using matrix isolation infrared spectroscopy and quantum chemical calculations. Computations were performed at M06-2X and MP2 levels of theory using 6-311++G(d,p) and aug-cc-pVDZ basis sets. At both the levels of theory, the complex involving an N–H⋯O interaction, where the N–H of borazine serves as the proton donor to the oxygen of water was found to be the global minimum, in contrast to the benzene-water system, which showed an H–π interaction. The experimentally observed infrared spectra of the complexes corroborated well with our computations for the complex corresponding to the global minimum. In addition to the global minimum, our computations also located two local minima on the borazine-water potential energy surface. Of the two local minima, one corresponded to a structure where the water was the proton donor to the nitrogen of borazine, approaching the borazine ring from above the plane of the ring; a structure that resembled the global minimum in the benzene-water H–π complex. The second local minimum corresponded to an interaction of the oxygen of water with the boron of borazine, which can be termed as the boron bond. Clearly the borazine-water system presents a richer landscape than the benzene-water system.

Activated coal of tomato seeds for adsorption of vapors of ammonia, benzene and gasoline

International Nuclear Information System (INIS)

Márquez-Montesino, Francisco; Aguiar-Trujillo, Leonardo; Ramos-Robaina, Boris Abel; Zanzi-Vigouroux, Rolando; Birbas, Daniella

2013-01-01

The objective was to prove the adsorption possibilities of ammonia, benzene and vapors of gasoline in activated coals with phosphoric acid, of tomato seed. An immediate analysis to the biomass was carried out. It was concluded that the vapors adsorption of ammonia, is related with the physical adsorption and the presence of functional groups of acid character in the active surface of the coal that form weak connections with the molecules of ammonia. Experiments of adsorption of benzene and gasoline were carried out, these substances haven't functional groups as the ammonia, so they were less adsorbed, and it was confirmed a chemical adsorption preferably. The activation temperature, the relationship of impregnation (RI) and the concentration of the acid dissolution haven't a significant influence in the capacity of adsorption of benzene, but they have in the adsorption of ammonia and vapors of gasoline, it's of great application for the elimination of vapors' escape in the motors of vehicles. (author)

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

Science.gov (United States)

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

2015-04-24

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

Ab initio investigation of the switching behavior of the dithiole-benzene nano-molecular wire

International Nuclear Information System (INIS)

Darvish Ganji, M.; Rungger, I.

2008-01-01

We report a first-principle study of electrical transport and switching behavior in a single molecular conductor consisting of a dithiole-benzene sandwiched between two Au( 100) electrodes. Ab initio total energy calculations reveal dithiole-benzene molecules on a gold surface, contacted by a monoatomic gold scanning tunneling microscope tip to have two classes of low energy conformations with differing symmetries. Lateral motion of the tip or excitation of the molecule cause it 10 change from one conformation class to the other and to switch between a strongly and a weakly conducting state. Thus, surprisingly. despite their apparent simplicity, these Au-dithiole-benzene -Au nano wires are shown to be electrically bi-stable switches, the smallest two-terminal molecular switches to date. The projected density of states and transmission coefficients are analyzed, and it suggests that the variation of the coupling between the molecule and the electrodes with external bias leads to switching behavior

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

Science.gov (United States)

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

2008-09-01

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

Mechanism of Benzene Tribopolymerization on the RuO2 (110) Surface

Science.gov (United States)

Yang, J.; Qi, Y.; Kim, H. D.; Rappe, A. M.

2018-04-01

A tribopolymer formed on the contacts of microelectromechanical and nanoelectromechanical system (MEMS-NEMS) devices is a major concern hampering their practical use in information technology. Conductive metal oxides, such as RuO2 and ReO3 , have been regarded as promising candidate materials for MEMS-NEMS contacts due to their conductivity, hardness, and relatively chemically inert surfaces. However, recent experimental works demonstrate that trace amounts of a polymer could still form on RuO2 surfaces. We demonstrate the mechanism of this class of unexpected tribopolymer formation by conducting density-functional-theory-based computational compression experiments with benzene as the contamination gas. First, mechanical force during compression changes the benzene molecules from slightly physisorbed to strongly chemisorbed. Further compression causes deformation and chemical linkage of the benzene molecules. Finally, the two contacts detach, with one having a complex organic molecule attached and the other a more reactive surface. The complex organic molecule, which has an oxabicyclic segment, can be viewed as the rudiment of a tribopolymer, and the more reactive surface can trigger the next adsorption-reaction-tribopolymer formation cycle. Based on these results, we also predict tribopolymer formation rates by using transition-state theory and the second-order rate law. We promote a deeper understanding of tribopolymer formation (especially on metal oxides) and provide strategies for suppressing tribopolymerization.

Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays

International Nuclear Information System (INIS)

Wahyudi, Agung; Bartzke, Mariana; Küster, Eberhard; Bogaert, Patrick

2013-01-01

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. - Highlights: ► Ecotoxicological shows significant benefits for detecting on site contaminations. ► MaxEnt to rebuild qualitative link on concentration and ecotoxicological assays. ► MaxEnt shows similar pattern when compared with concentrations map of groundwater. ► MaxEnt is a valuable method especially when quantitative relation is not at hand. - A Maximum Entropy method to rebuild qualitative relationships between Benzene groundwater concentrations and their ecotoxicological effect.

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

Science.gov (United States)

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

2016-03-01

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

GMP-grade platelet lysate enhances proliferation and migration of tenon fibroblasts.

Science.gov (United States)

Carducci, Augusto; Scafetta, Gaia; Siciliano, Camilla; Carnevale, Roberto; Rosa, Paolo; Coccia, Andrea; Mangino, Giorgio; Bordin, Antonella; Vingolo, Enzo Maria; Pierelli, Luca; Lendaro, Eugenio; Ragona, Giuseppe; Frati, Giacomo; De Falco, Elena

2016-01-01

Tenon's fibroblasts (TFs), widely employed as in vitro model for many ophthalmological studies, are routinely cultured with FBS. Platelet Lysate (PL), a hemoderivate enriched with growth factors and cytokines has been largely tested in several clinical applications and as substitute of FBS in culture. Here, we investigate whether PL can exert biological effects on TF populations similarly to other cell types. Results show that PL significantly enhances cell proliferation and migration vs. FBS, without influencing cell size/granularity. Upregulation of EGF, VEGF, KDR, MMP2-9, FAK mRNA levels also occurs and phosphorylation of AKT but not of ERK1/2 is significantly enhanced. The inhibition of the PI3kinase/AKT pathway with the specific inhibitor wortmannin, decreases PL-induced cell migration but not proliferation. Condition supernatants containing PL show increased bioavailability of Nitric Oxide and reduced levels of 8-Iso-PGF2-alpha, correlating with cell proliferation and migration. Pro-angiogenic/inflammatory soluble factors (GRO, Angiogenin, EGF, I-309, PARC) are exclusively or greater expressed in media containing PL than FBS. GMP-grade PL preparations positively influence in vitro biological effects of TFs representing a suitable and safer alternative to FBS.

Evaluation of chromosome aberration and micronucleus frequencies in blood lymphocytes of workers exposed to low concentrations of benzene.

Science.gov (United States)

Lovreglio, Piero; Maffei, Francesca; Carrieri, Mariella; D'Errico, Maria N; Drago, Ignazio; Hrelia, Patrizia; Bartolucci, Giovanni B; Soleo, Leonardo

2014-08-01

The frequency of chromosome aberrations (CA) and micronuclei (MN) was investigated in the peripheral lymphocytes of workers occupationally exposed to low or very low concentrations of benzene. The study included 43 exposed workers (all males), namely 19 fuel-tanker drivers and 24 filling-station attendants, and 31 male subjects with no occupational exposure to the toxicant (controls). Benzene exposure was verified by means of environmental monitoring with passive personal samplers (Radiello(®)), and through biological monitoring, i.e. by measurement of urinary trans,trans-muconic acid, S-phenylmercapturic acid and benzene. The frequency of CA and MN in peripheral lymphocytes was determined according to standard procedures. Exposure to benzene was found to be significantly higher for fuel-tanker drivers (median 246.6 μg/m(3)) than for filling-station attendants (median 19.9 μg/m(3)). Both groups had significantly higher exposure than controls (median 4.3 μg/m(3)). No increased frequency of CA and MN was observed in either fuel-tanker drivers or filling-station attendants compared with controls. In all subjects examined as a single group, the frequency of MN was significantly dependent on age. Only in the fuel-tanker drivers was the frequency of MN found to depend not only on age, but also on exposure to benzene. In conclusion, the frequency of MN, but not of CA, could be influenced by exposure to benzene concentrations of up to one order of magnitude lower than the threshold limit value (time-weighted average). Copyright © 2014 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

Sekiguchi, H; Ando, M; Kojima, H

2005-01-01

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

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

International Nuclear Information System (INIS)

Monkenbusch, M.

1981-01-01

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

Tritium-labeled (E,E)-2,5-bis(4'-hydroxy-3'-carboxystyryl)benzene as a probe for β-amyloid fibrils.

Science.gov (United States)

Matveev, Sergey V; Kwiatkowski, Stefan; Sviripa, Vitaliy M; Fazio, Robert C; Watt, David S; LeVine, Harry

2014-12-01

Accumulation of Aβ in the brains of Alzheimer disease (AD) patients reflects an imbalance between Aβ production and clearance from their brains. Alternative cleavage of amyloid precursor protein (APP) by processing proteases generates soluble APP fragments including the neurotoxic amyloid Aβ40 and Aβ42 peptides that assemble into fibrils and form plaques. Plaque-buildup occurs over an extended time-frame, and the early detection and modulation of plaque formation are areas of active research. Radiolabeled probes for the detection of amyloid plaques and fibrils in living subjects are important for noninvasive evaluation of AD diagnosis, progression, and differentiation of AD from other neurodegenerative diseases and age-related cognitive decline. Tritium-labeled (E,E)-1-[(3)H]-2,5-bis(4'-hydroxy-3'-carbomethoxystyryl)benzene possesses an improved level of chemical stability relative to a previously reported radioiodinated analog for radiometric quantification of Aβ plaque and tau pathology in brain tissue and in vitro studies with synthetic Aβ and tau fibrils. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2013-11-21

We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers are heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg, and as a result, the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 to 135 K. In this temperature range, diffusivities are found to vary across 5 orders of magnitude (∼10(-14) to 10(-9) cm(2)/s). The diffusivity data are compared to viscosity measurements and reveal a breakdown in the Stokes-Einstein relationship at low temperatures. However, the data are well fit by the fractional Stokes-Einstein equation with an exponent of 0.66. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

How the sorption of benzene in soils contaminated with aromatic hydrocarbons is affected by the presence of biofuels

Directory of Open Access Journals (Sweden)

Maria Manuela Carvalho

2015-04-01

Full Text Available The increasing use of biofuels as additives to gasoline may have potential indirect effects on the efficiency of soil remediation technologies used to remediate fuel spills. This problem has not yet been studied. Sorption is one of the controlling processes in soil remediation. The effect of biofuels on sorption and phase distribution of contaminants by different natural soils has not been reported on the literature. The present work examines how two different biofuels, n-butanol and soybean biodiesel, affect benzene sorption in two naturally occurring subsoils (granite and limestone. Sorption isotherms were made with soils deliberately contaminated with benzene, benzene and n-butanol and benzene plus biodiesel, using lab-scale reactors operated at constant temperature, each one loaded with 700 grams of wet sterilized soil. For each type of soil, five isotherms were determined corresponding to different contamination profiles. It was concluded that sorption was strongly affected by the nature of the soil. The partition of benzene into the different phases of the soil was significantly affected by the presence of biofuels. The experimental data was fitted to conventional sorption models, Freundlich, Langmuir and a second order polynomial. Model parameters were determined using a non-linear least squares (NLLS optimization algorithm and showed a good agreement between experimental and fitted data.

Assisted bioremediation tests on three natural soils contaminated with benzene

Directory of Open Access Journals (Sweden)

Maria Manuela Carvalho

2015-07-01

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.

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Raman Frequencies Calculated at Various Pressures in Phase I of Benzene

Energy Technology Data Exchange (ETDEWEB)

Tari, Ozlem; Yurtseven, Hamit [Istanbul Arel Univ., Ankara (Turkmenistan)

2013-04-15

We calculate in this study the pressure dependence of the frequencies for the Raman modes of A (A{sub g}), B (A{sub g}, B{sub 2g}) and C (B{sub 1g}, B{sub 3g}) at constant temperatures of 274 and 294K (room temperature) for the solid phase I of benzene. Using the mode Gruneisen parameter of each lattice mode, which correlates the pressure dependence of the crystal volume and the frequency, the Raman frequencies of those modes are computed for phase I of benzene. Our results show that the Raman frequencies of the three lattice modes (A, B and C) increase as the pressure increases, as expected. The temperature effect on the Raman frequencies is not significant, which can be explained by the experimental measurements.

46 CFR Appendix D to Subpart C to... - Sampling and Analytical Methods for Benzene Monitoring-Measurement Procedures

Science.gov (United States)

2010-10-01

... chromatograph. Detection limit: 0.04 ppm. Recommended air volume and sampling rate: 10 liter at 0.2 liter/min. 1... nitric acid. The benzene is converted to nitrobenzene. The carbon disulfide layer is removed, dried with...=molecular weight of benzene. 8. Backup data 8.1 Detection limit—Air Samples. The detection limit for the...

Organometallic benzene-vanadium wire: A one-dimensional half-metallic ferromagnet

DEFF Research Database (Denmark)

Maslyuk, V.; Bagrets, A.; Meded, V.

2006-01-01

Using density functional theory we perform theoretical investigations of the electronic properties of a freestanding one-dimensional organometallic vanadium-benzene wire. This system represents the limiting case of multidecker V-n(C6H6)(n+1) clusters which can be synthesized with established meth...

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

Science.gov (United States)

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

2013-01-01

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.

The long range migration of hydrogen through Zircaloy in response to tensile and compressive stress gradients

International Nuclear Information System (INIS)

Kammenzind, B.F.; Berquist, B.M.; Bajaj, R.; Kreyns, P.H.; Franklin, D.G.

1998-01-01

Zircaloy-4, which is used widely as a core structural material in pressurized water reactors (PWRs), picks up hydrogen during service. Hydrogen solubility in Zircaloy-4 is low and zirconium hydride phases precipitate after the Zircaloy-4 lattice becomes supersaturated with hydrogen. These hydrides embrittle the Zircaloy-4, degrading its mechanical performance as a structural material. Because hydrogen can move rapidly through the Zircaloy-4 lattice, the potential exists for large concentrations of hydride to accumulate in local regions of a Zircaloy component remote from its point of entry into the component. Much has been reported in the literature regarding the long range migration of hydrogen through Zircaloy under concentration gradients and temperature gradients. Relatively little has been reported, however, regarding the long range migration of hydrogen under stress gradients. This paper presents experimental results regarding the long range migration of hydrogen through Zircaloy in response to both tensile and compressive stress gradients. The importance of this driving force for hydrogen migration relative to concentration and thermal gradients is discussed

Occupational exposure to benzene at the ExxonMobil refinery in Baytown, TX (1978-2006).

Science.gov (United States)

Gaffney, Shannon H; Panko, Julie M; Unice, Ken M; Burns, Amanda M; Kreider, Marisa L; Gelatt, Richard H; Booher, Lindsay E; Paustenbach, Dennis J

2011-01-01

Although occupational benzene exposure of refinery workers has been studied for decades, no extensive analysis of historical industrial hygiene data has been performed focusing on airborne concentrations at specific refineries and tasks. This study characterizes benzene exposures at the ExxonMobil Baytown, TX, refinery from 1978 to 2006 to understand the variability in workers' exposures over time and during different job tasks. Exposures were grouped by operational status, job title, and tasks. More than 9000 industrial hygiene air samples were evaluated; approximately 4000 non-task (> 3 h) and 1000 task-related (work areas, and 16 task bins (when applicable). Process technicians were sampled most frequently, resulting in the following mean benzene concentrations by area: hydrofiner (n=245, mean=1.3 p.p.m.), oil movements (n=286, mean=0.23 p.p.m.), reformer (n=575, mean=0.10 p.p.m.), tank farm (n=9, mean=0.65 p.p.m.), waste treatment (n=446, mean=0.13 p.p.m.), and other areas (n=460, mean=0.062 p.p.m.). The most frequently sampled task was sample collection (n=218, mean=0.40 p.p.m.). Job title and area did not significantly impact task-related exposures. Airborne concentrations were significantly lower after 1990 than before 1990. Results of this task-focused study may be useful when analyzing benzene exposures at other refineries.

Migration of hydrocarbons in the subsoil of an industrial installation

International Nuclear Information System (INIS)

Van Dorpe, F.

2000-01-01

The fate of old industrial sites is a major problem at the beginning of the new millennium for government organization, agencies owning polluted sites... These brown-field sites often generate considerable pollution of soils and groundwater, the main source of drinking water. The National Center for Research on Polluted Soils and Sites (CNRSSP), in which the CEA is an active partner, is developing a strategy to study and, using several scientific tools, characterize industrial sites polluted by various contaminants: metals, metalloids, hydrocarbons, nitrates. The present study offers an example of the investigation of an old industrial site (coke plant), built in 1919 (in operation for 50 years), located in northern France. The storage of tars and wastewaters on these sites causes soil and groundwater contamination with organic compounds such as Polycyclic Aromatic Hydrocarbons (PAHs), mono-aromatic hydrocarbons (benzene, toluene, ethyl-benzene and xylene BTEX), volatile organic compounds (VOCs), phenolic and other hydrocarbons, and inorganic compounds including metalloids (free and complexed cyanides) and metals (As, Pb, Ni, Cd and Hg). The more soluble constituents tend to migrate to adjacent areas with the groundwater flow and thereby reach receptors such as drinking water resources. Among the above pollutants, the 16 PAHs from the priority list of the Environmental Protection Agency (EPA) are of great environmental concern due to their toxic, mutagenic and carcinogenic properties. The remediation of PAH-polluted sites poses a crucial challenge given the large number of sites contaminated by these pollutants and the difficulty in eliminating the pollution. A better evaluation of the PAH transfer and transport in soils and aquifers will also help draw up remediation strategies. In this study, a numerical model, called SIMUSCOPP and developed by the French Petroleum Institute (IFP), BURGEAP and ENI group for organic pollutants, was used to simulate 3D transfer and

Ground rubber: Sorption media for ground water containing benzene and O-xylene

International Nuclear Information System (INIS)

Kershaw, D.S.; Pamukcu, S.

1997-01-01

The purpose of the current study is to examine the ability of ground rubber to sorb benzene and O-xylene from water contained with aromatic hydrocarbons. The study consisted of running both batch and packed bed column tests to determine the sorption capacity, the required sorption equilibration time, and the flow through utilization efficiency of ground rubber under various contact times when exposed to water contaminated with various amounts of benzene or O-xylene. Initial batch test results indicate that ground rubber can attain equilibrium sorption capacities up to 1.3 or 8.2 mg of benzene or O-xylene, respectively, per gram of tire rubber at solution equilibrium concentrations of 10 mg/L. Packed bed column tests indicate that ground tire rubber has on the average a 40% utilization rate when a hydraulic residence time of 15 min is used. Possible future uses of round rubber as a sorption media could include, but are not limited to, the use of ground rubber as an aggregate in slurry cutoff walls that are in contact with petroleum products. Ground rubber could also be used as a sorption media in pump-and-treat methodologies or as a sorption media in in-situ reactive permeable barriers

Retrospective benzene exposure assessment for a multi-center case-cohort study of benzene-exposed workers in China.

Science.gov (United States)

Portengen, Lützen; Linet, Martha S; Li, Gui-Lan; Lan, Qing; Dores, Graça M; Ji, Bu-Tian; Hayes, Richard B; Yin, Song-Nian; Rothman, Nathaniel; Vermeulen, Roel

2016-01-01

Quality of exposure assessment has been shown to be related to the ability to detect risk of lymphohematopoietic disorders in epidemiological investigations of benzene, especially at low levels of exposure. We set out to build a statistical model for reconstructing exposure levels for 2898 subjects from 501 factories that were part of a nested case-cohort study within the NCI-CAPM cohort of more than 110,000 workers. We used a hierarchical model to allow for clustering of measurements by factory, workshop, job, and date. To calibrate the model we used historical routine monitoring data. Measurements below the limit of detection were accommodated by constructing a censored data likelihood. Potential non-linear and industry-specific time-trends and predictor effects were incorporated using regression splines and random effects. A partial validation of predicted exposures in 2004/2005 was performed through comparison with full-shift measurements from an exposure survey in facilities that were still open. Median cumulative exposure to benzene at age 50 for subjects that ever held an exposed job (n=1175) was 509 mg/m(3) years. Direct comparison of model estimates with measured full-shift personal exposure in the 2004/2005 survey showed moderate correlation and a potential downward bias at low (<1 mg/m(3)) exposure estimates. The modeling framework enabled us to deal with the data complexities generally found in studies using historical exposure data in a comprehensive way and we therefore expect to be able to investigate effects at relatively low exposure levels.

1,2'-Bis(4-aminophenoxy)benzene based designed fluoro-poly(ether-imide)/MMT clay nanocomposites: Synthesis and properties for high performance applications

International Nuclear Information System (INIS)

Vora, Rohitkumar H.; Vora, Mayur

2006-01-01

In an effort to develop structure-property understanding of fluoro-polymer/inorganic clay nanocomposite (i.e., Ceramer) technology, two series of fluoro-poly(ether amic acid) (6F-PEAA)/organosoluble Montmorillonite (MMT) clay nanocomposite formulations containing varying percentage of diamine modified (ion-exchanged) organosoluble-MMT clay were prepared from the partially fluorinated fluoro poly(ether-amic acid)s (6F-PEAA) synthesized by reacting on 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and di-ether-containing diamines, such as 1,2'-bis(4-aminophenoxy) benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy) diphenyl sulfone (p-SED), respectively. Self supporting films were cast from these formulations and cured at elevated temperatures. XRD data, indirectly confirmed the exfoliation of organosoluble-MMT clay at molecular level in the nanocomposite. The solubility, chemical resistance, morphology, thermo-oxidative stability, thermal degradation kinetics, mechanical behavior, and moisture absorption of these [(6F-PEI)/MMT clay] nanocomposite films were systematically studied

Monosaccharides as Versatile Units for Water-Soluble Supramolecular Polymers.

Science.gov (United States)

Leenders, Christianus M A; Jansen, Gijs; Frissen, Martijn M M; Lafleur, René P M; Voets, Ilja K; Palmans, Anja R A; Meijer, E W

2016-03-18

We introduce monosaccharides as versatile water-soluble units to compatibilise supramolecular polymers based on the benzene-1,3,5-tricarboxamide (BTA) moiety with water. A library of monosaccharide-based BTAs is evaluated, varying the length of the alkyl chain (hexyl, octyl, decyl and dodecyl) separating the BTA and saccharide units, as well as the saccharide units (α-glucose, β-glucose, α-mannose and α-galactose). In all cases, the monosaccharides impart excellent water compatibility. The length of the alkyl chain is the determining factor to obtain either long, one-dimensional supramolecular polymers (dodecyl spacer), small aggregates (decyl spacer) or molecularly dissolved (octyl and hexyl) BTAs in water. For the BTAs comprising a dodecyl spacer, our results suggest that a cooperative self-assembly process is operative and that the introduction of different monosaccharides does not significantly change the self- assembly behaviour. Finally, we investigate the potential of post-assembly functionalisation of the formed supramolecular polymers by taking advantage of dynamic covalent bond formation between the monosaccharides and benzoxaboroles. We observe that the supramolecular polymers readily react with a fluorescent benzoxaborole derivative permitting imaging of these dynamic complexes by confocal fluorescence microscopy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DEFF Research Database (Denmark)

Rolle, Massimo; Jin, Biao

2017-01-01

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

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

Directory of Open Access Journals (Sweden)

Wen-Yu Zhang

2011-08-01

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.

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

Directory of Open Access Journals (Sweden)

X. Fang

2016-03-01

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

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.

2006-01-01

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.

Collisional flow of vibrational energy into surrounding vibrational fields within S1 benzene

International Nuclear Information System (INIS)

Tang, K.Y.; Parmenter, C.S.

1983-01-01

Vapor phase fluorescence spectra are used to determine the absolute rate constants for the collisional transfer of vibrational energy from initial single vibronic levels of S 1 benzene into the surrounding S 1 vibronic field. 11 initial levels are probed with vibrational energies ranging to 2368 cm -1 where the level density is about 10 per cm -1 . CO, isopentane, and S 0 benzene are the collision partners. Benzene rate constants are three to four times gas kinetic for all levels, and electronic energy switching between the initial S 1 molecule and the S 0 collision partner probably makes important contributions. Isopentane efficiencies range from one to two times gas kinetic. Most of the transfer from low S 1 levels occurs with excitation of vibrational energy within isopentane. These V--V contributions decline to only about 10% for the high transfer. CO-induced transfer is by V-T,R processes for all levels. The CO efficiency rises from about 0.1 for low regions to about unity for levels above 1500 cm -1 . The CO efficiencies retain significant sensitivity to initial level identity even in the higher regions. Propensity rules derived from collisional mode-to-mode transfer among lower levels of S 1 benzene are used to calculate the relative CO efficiencies. The calculated efficiencies agree well enough with the data to suggest that it may be meaningful to model vibrational equilibration with the use of propensity rules. The rules suggest that only a small number of levels among the thousands surrounding a high initial level contribute significantly to the total relaxation cross section and that this number is rather independent of the level density

Oxidation of benzene by radiolytically produced OH radicals. [x rays

Energy Technology Data Exchange (ETDEWEB)

Klein, G W; Schuler, R H [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

1978-01-01

The radiolysis of N/sub 2/O saturated-aqueous solutions of benzene-/sup 14/C has been examined using radio-liquid chromatographic methods to follow the quantitative aspects of the reactions of hydroxycyclohexadienyl radicals. In the absence of a radical oxidant, at least five important products are produced. The total yield of 5.8 observed for the incorporation of benzene into products accounts for essentially all of the radicals initially produced from the water. Dimeric products predominate with a total yield of 4.1. Phenol is produced with a yield of only 0.8 indicating a disproportionation/combination ratio for hydroxycyclohexadienyl radicals of < = 0.4. In the presence of 2mM ferricyanide the hydroxycyclohexadienyl radicals are quantitatively oxidized to phenol with no trace (< 1%) remaining of dimeric or other high molecular weight products. The initial yield for phenol formation (6.0 molecules/100 eV) provides a measure for OH production in N/sub 2/O saturated aqueous solutions.

Active and passive monitoring of benzene in Milan from 1992 up to today

International Nuclear Information System (INIS)

Lerda, D.; Robles, P.; Astori, M.; Barletta, M.; Canzi, R.; Barilli, L.

1999-01-01

The air quality degradation in large urban areas, mainly due to the traffic, is evaluated through the measurement of pollutants coming, directly or indirectly, from the traffic itself. Due to its cancerogenicity, a quality standard for benzene has been settled by D.M.25/11/1994, which obliges this measure in towns having more than 150.000 inhabitants.Starting from 1992, Milan P.M.I.P. has been controlling benzene and other homologues concentrations in air with routine and campaign measurements. Concentrations change depends both on variations of fuel formulation and on the renewal of the cars fleet. As a matter of fact, the lower benzene percentage in fuels and the use of tailpipes with catalytic converter greatly reduced the emission of these compounds in air, giving an estimate annual average lower than the impose limit. In an urban area, an estimate of an average concentration starting from the three sampling points according to the low can give a value far from the real average level; to solve this problem Milan P.M.I.P. programmed an annual campaign with daily sampling in 24 sites homogeneously located in Milan territory [it

On the role of delocalization in benzene: Theoretical and experimental investigation of the effects of strained ring fusion

Energy Technology Data Exchange (ETDEWEB)

Faust, Rudiger [Univ. of California, Berkeley, CA (United States)

1993-04-01

When an important compound`s discovery dates back as far as 1825, one would imagine that every facet of its chemical and physical properties has been illuminated in the meantime. Benzene, however, has not ceased to challenge the chemist`s notion of structure and bonding since its first isolation by Michael Faraday. This report is divided into the following six chapters: 1. Aromaticity -- Criteria, manifestations, structural limitations; 2. The role of delocalization in benzene; 3. The thermochemical properties of benzocyclobutadienologs; 4. Ab initio study of benzenes fused to four-membered rings; 5. Non-planar polycyclic aromatic hydrocarbons; and 6. Experimental details and input decks. 210 Refs.

Early changes of lymphocyte RNA and serum immunoglobulins following chronic exposure to benzene

Energy Technology Data Exchange (ETDEWEB)

Chircu, V.; Ionescu, M.; Zgoan

Hematologic and immunochemical investigations carried out in 270 workers with chronic exposure to benzene demonstrated changes of the nucleologram and of the area of lymphocyte nucleoli as well as disorders of the humoral immune response revealed by radial immunodiffusion. The numerical rise of bi- and polynucleolated cells, of cells with irregular macronucleoli as well as an enlargement of the nucleolar area are assumed to reflect an increase of the endolymphocytic amounts of RNA. An increased capacity of immunoglobulin formation, particularly of IgM, was also observed. All these changes are considered as early signs of an enhanced immune reactivity following chronic exposure to benzene.

The use of biomonitoring data in exposure and human health risk assessment: benzene case study

OpenAIRE

Arnold, Scott M.; Angerer, Juergen; Boogaard, Peter J.; Hughes, Michael F.; O?Lone, Raegan B.; Robison, Steven H.; Robert Schnatter, A.

2013-01-01

A framework of ?Common Criteria? (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of th...

TDDFT-MD Study on Dynamics in Photoinduced Ring Opening of Benzene

Science.gov (United States)

Tateyama, Yoshitaka; Miyamoto, Yoshiyuki; Oyama, Norihisa; Ohno, Takahisa

2004-03-01

Coupled dynamics of ions and electrons in the excited states of molecular and solid benzene is investigated on the femtosecond scale by the efficient simulation scheme recently developed for the time-dependent density functional theory. Within the π arrow π excitations, any out-of-plane motion of ions is not induced in the molecular system basically. In the solid, however, we found that large swing of the C-H bonds and subsequent twist of the carbon ring takes place, leading to sp^3-like bonding of carbon ions. This swing-to-twist motion presents a plausible mechanism underlying the photoinduced ring opening in solid benzene experimentally observed under pressure. This research is partially supported by ACT-JST, and also by FSIS and Special Coordination Funds of Ministry of Education, Culture, Sports, Science and Technology of Japanese Government.

Depth migration and de-migration for 3-D migration velocity analysis; Migration profondeur et demigration pour l'analyse de vitesse de migration 3D

Energy Technology Data Exchange (ETDEWEB)

Assouline, F.

2001-07-01

3-D seismic imaging of complex geologic structures requires the use of pre-stack imaging techniques, the post-stack ones being unsuitable in that case. Indeed, pre-stack depth migration is a technique which allows to image accurately complex structures provided that we have at our disposal a subsurface velocity model accurate enough. The determination of this velocity model is thus a key element for seismic imaging, and to this end, migration velocity analysis methods have met considerable interest. The SMART method is a specific migration velocity analysis method: the singularity of this method is that it does not rely on any restrictive assumptions on the complexity of the velocity model to determine. The SMART method uses a detour through the pre-stack depth migrated domain for extracting multi-offset kinematic information hardly accessible in the time domain. Once achieved the interpretation of the pre-stack depth migrated seismic data, a kinematic de-migration technique of the interpreted events enables to obtain a consistent kinematic database (i.e. reflection travel-times). Then, the inversion of these travel-times, by means of reflection tomography, allows the determination of an accurate velocity model. To be able to really image geologic structures for which the 3-D feature is predominant, we have studied the implementation of migration velocity analysis in 3-D in the context of the SMART method, and more generally, we have developed techniques allowing to overcome the intrinsic difficulties in the 3-D aspects of seismic imaging. Indeed, although formally the SMART method can be directly applied to the case of 3-D complex structures, the feasibility of its implementation requires to choose well the imaging domain. Once this choice done, it is also necessary to conceive a method allowing, via the associated de-migration, to obtain the reflection travel-times. We first consider the offset domain which constitutes, still today, the strategy most usually used

Sorption processes affecting arsenic solubility in oxidized surface sediments from Tulare Lake Bed, California

Science.gov (United States)

Gao, S.; Goldberg, S.; Herbel, M.J.; Chalmers, A.T.; Fujii, R.; Tanji, K.K.

2006-01-01

Elevated concentrations of arsenic (As) in shallow groundwater in Tulare Basin pose an environmental risk because of the carcinogenic properties of As and the potential for its migration to deep aquifers that could serve as a future drinking water source. Adsorption and desorption are hypothesized to be the major processes controlling As solubility in oxidized surface sediments where arsenate [As(V)] is dominant. This study examined the relationship between sorption processes and arsenic solubility in shallow sediments from the dry Tulare Lake bed by determining sorption isotherms, pH effect on solubility, and desorption-readsorption behavior (hysteresis), and by using a surface complexation model to describe sorption. The sediments showed a high capacity to adsorb As(V). Estimates of the maximum adsorption capacity were 92 mg As kg- 1 at pH 7.5 and 70 mg As kg- 1 at pH 8.5 obtained using the Langmuir adsorption isotherm. Soluble arsenic [> 97% As(V)] did not increase dramatically until above pH 10. In the native pH range (7.5-8.5), soluble As concentrations were close to the lowest, indicating that As was strongly retained on the sediment. A surface complexation model, the constant capacitance model, was able to provide a simultaneous fit to both adsorption isotherms (pH 7.5 and 8.5) and the adsorption envelope (pH effect on soluble As), although the data ranges are one order of magnitude different. A hysteresis phenomenon between As adsorbed on the sediment and As in solution phase was observed in the desorption-readsorption processes and differs from conventional hysteresis observed in adsorption-desorption processes. The cause is most likely due to modification of adsorbent surfaces in sediment samples upon extensive extractions (or desorption). The significance of the hysteresis phenomenon in affecting As solubility and mobility may be better understood by further microscopic studies of As interaction mechanisms with sediments subjected to extensive leaching

A theoretical analysis of the ultraviolet spectrum (180-260 nm) of pure liquid benzene

International Nuclear Information System (INIS)

Fernandez, M.; Tortajada, J.; Sese, L.M.

1988-01-01

This paper reports an attempt to understand theoretically the red shifts seen in the benzene ultraviolet spectrum upon changing from gas to the liquid phase. The theoretical analysis is performed through a framework which brings together Quantum Chemistry and Classical Statistical Mechanics of molecular liquids. As it is discussed herein, the influence of the liquid phase on the individual molecular properties is taken into account by means of a perturbation term included in the effective molecular Hamiltonian. Such a perturbation depends explicitly on both the chemical nature and the static structure of the liquid surrounding the molecule under study. In order to simulate the vibronic couplings, which make the benzene ''forbidden'' bands 1 L a and 1 L b have nonzero intensity, random displacements of the nuclei of benzene have been employed in this introductory work. The calculations involve the CNDO/S procedure and the atom-atom radial distribution functions of the liquid sample. The results account for the large red shift (≅ 20 nm) undergone by the band 1 L a . (orig.)

Chemokine CXCL16 Expression Suppresses Migration and Invasiveness and Induces Apoptosis in Breast Cancer Cells

Directory of Open Access Journals (Sweden)

Yeying Fang

2014-01-01

Full Text Available Background. Increasing evidence argues that soluble CXCL16 promotes proliferation, migration, and invasion of cancer cells in vitro. However, the role of transmembrane or cellular CXCL16 in cancer remains relatively unknown. In this study, we determine the function of cellular CXCL16 as tumor suppressor in breast cancer cells. Methods. Expression of cellular CXCL16 in breast cancer cell lines was determined at both RNA and protein levels. In vitro and in vivo studies that overexpressed or downregulated CXCL16 were conducted in breast cancer cells. Results. We report differential expression of cellular CXCL16 in breast cancer cell lines that was negatively correlated with cell invasiveness and migration. Overexpression of CXCL16 in MDA-MB-231 cells led to a decrease in cell invasion and migration and induced apoptosis of the cells; downregulation of CXCL16 in MCF-7 cells increased cell migration and invasiveness. Consistent with the in vitro data, CXCL16 overexpression inhibited tumorigenesis in vivo. Conclusions. Cellular CXCL16 suppresses invasion and metastasis of breast cancer cells in vitro and inhibits tumorigenesis in vivo. Targeting of cellular CXCL16 expression is a potential therapeutic strategy for breast cancer.

Neptunium (IV) oxalate solubility

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

The equilibrium solubility of neptunium (IV) oxalate in nitric/oxalic acid solutions was determined at 22 0 C, 45 0 C, and 60 0 C. The concentrations of nitric/oxalic acid solutions represented a wide range of free oxalate ion concentration. A mathematical solubility model was developed which is based on the formation of the known complexes of neptunium (IV) oxalate. the solubility model uses a simplified concentration parameter which is proportional to the free oxalate ion concentration. The solubility model can be used to estimate the equilibrium solubility of neptunium (IV) oxalate over a wide range of oxalic and nitric acid concentrations at each temperature