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Sample records for toluene diisocyanate-related symptoms

  1. Toluene diisocyanate: Induction of the autotaxin-lysophosphatidic acid axis and its association with airways symptoms

    Energy Technology Data Exchange (ETDEWEB)

    Broström, Julia M. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Ye, Zhi-wei [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden); Axmon, Anna; Littorin, Margareta; Tinnerberg, Håkan; Lindh, Christian H. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Zheng, Huiyuan; Ghalali, Aram; Stenius, Ulla [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden); Jönsson, Bo A.G. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Högberg, Johan, E-mail: johan.hogberg@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden)

    2015-09-15

    Diisocyanates are industrial chemicals which have a wide range of applications in developed and developing countries. They are notorious lung toxicants and respiratory sensitizers. However, the mechanisms behind their adverse effects are not adequately characterized. Autotaxin (ATX) is an enzyme producing lysophosphatidic acid (LPA), and the ATX-LPA axis has been implicated in lung related inflammatory conditions and diseases, including allergic asthma, but not to toxicity of environmental low-molecular-weight chemicals. We investigated effects of toluene diisocyanate (TDI) on ATX induction in human lung epithelial cell models, and we correlated LPA-levels in plasma to biomarkers of TDI exposure in urine collected from workers exposed to < 5 ppb (parts per billion). Information on workers' symptoms was collected through interviews. One nanomolar TDI robustly induced ATX release within 10 min in vitro. A P2X7- and P2X4-dependent microvesicle formation was implicated in a rapid ATX release and a subsequent protein synthesis. Co-localization between purinergic receptors and ATX was documented by immunofluorescence and confocal microscopy. The release was modulated by monocyte chemoattractant protein-1 (MCP-1) and by extracellular ATP. In workers, we found a dose–response relationship between TDI exposure biomarkers in urine and LPA levels in plasma. Among symptomatic workers reporting “sneezing”, the LPA levels were higher than among non-symptomatic workers. This is the first report indicating induction of the ATX-LPA axis by an environmental low-molecular-weight chemical, and our data suggest a role for the ATX-LPA axis in TDI toxicity. - Highlights: • Human epithelial cells release autotaxin in response to 1 nM toluene diisocyanate (TDI). • The release involves P2X4 and P2X7 receptors and is modulated by ATP and MCP-1. • Lysophosphatidic acid (LPA) was measured in workers exposed to < 5 ppb TDI. • LPA in plasma correlated to TDI exposure

  2. Evaluation of neuropsychological symptoms and exposure to benzene, toluene and xylene among two different furniture worker groups in Izmir.

    Science.gov (United States)

    Mandiracioglu, Aliye; Akgur, Serap; Kocabiyik, Nesrin; Sener, Ufuk

    2011-10-01

    This study was conducted to determine whether there was any exposure to toluene, xylene and benzene and to assess the health impact of these solvents on workers in furniture enterprises in Karabaglar, Izmir. This cross-sectional study covered furniture enterprises in Karabaglar, Izmir. This study was comprised of an exposed group consisting of workers engaged in painting and varnishing and therefore exposed either directly or indirectly toluene, xylene and benzene in the workplace and the non-exposed group engaged in other aspects of production. While a total of 261 individuals completed questionnaires, 210 workers agreed to provide blood samples. Blood solvents levels were determined using gas chromatograph at Ege University, Intoxication Research and Application Centre. The modified EUROQUEST questionnaire was used to assess neuropsychological symptoms and neurological and general examination were performed. Occupational and exposure history, demographic and work-related information was collected. In this study of workers, blood toluene and benzene levels were found to be significantly higher among those engaged in painting and varnishing compared to those who perform other tasks. The average blood toluene and benzene concentrations among exposed workers were 6.95 times and 1.64 times respectively higher than those in the nonexposed groups. Smokers and participants who worked in excess of 8 hours/day had higher blood toluene and benzene levels. The most frequently work-related health complaints were back pain, allergies and asthma. No differences were found in the average scores in the neuropsychological symptoms questionnaire between exposed and non-exposed groups. Neurological examination of two individuals with these complaints revealed a loss of reflexes. The workers were unaware that they were being exposed to solvents at work. Tobacco smoke is a major source of internal exposure to benzene. Improving working conditions in furniture work places is a priority.

  3. Asthma Symptoms and Specific IgE Levels among Toluene Diisocyanate (TDI) Exposed Workers in Tehran, Iran.

    Science.gov (United States)

    Sharifi, Laleh; Karimi, Akram; Shokouhi Shoormasti, Raheleh; Miri, Sara; Heydar Nazhad, Hassan; Bokaie, Saied; Fazlollahi, Mohammad Reza; Sadeghniiat Haghighi, Khosro; Pourpak, Zahra; Moin, Mostafa

    2013-01-01

    Toluene diisocyanate (TDI) is an imperative chemical substance used in the production of polyurethane foams, elastomers, paints and coatings that cause a variety of health problems in workers who are exposed in work places. This study aimed to determine the asthma symptoms and serum specific IgE levels in TDI exposed workers and comparing the results with healthy control group. All the plants that use TDI in the manufacturing of paint and glue in the west of Tehran Province entered to the study and all the workers (550) completed modified initial questionnaire of the NIOSH, the questions were consisted of asthma symptoms. For each symptomatic exposed worker one healthy, sex and age matched control selected. Total IgE and Specific TDI IgE tests were done for each case and control groups. Among 550 TDI exposed workers, 26(4.7%) had asthma symptoms. Nine (34.6%) of symptomatic workers who were exposed to TDI were active cigarette consumer versus 3(11.5%) unexposed workers, P=0.049(CI= 0.953-17.29) OR=4.059. Nine (34.6%) workers had positive family history of atopy versus 1(3.8%) unexposed workers, P=0.0138 (CI= 1.45-305.41) OR=13.24. TDI specific IgE was found in 2 TDI exposed workers and 1 unexposed worker (P=0.5). Mean of total IgE was 339.05 in exposed workers (P=0.201). This study provides clinical and paraclinical data of workers exposed to TDI and points to a relation between atopy and smoking habit with asthma symptoms that offer preventing recommendations for TDI exposed workers and their heath administrators.

  4. Acute neurobehavioural effects of toluene.

    OpenAIRE

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

    1989-01-01

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

  5. Acute neurobehavioural effects of toluene.

    Science.gov (United States)

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

    1989-07-01

    An acute inhalation chamber study of 42 college students was performed to investigate the relation between exposure to 0, 75, and 150 ppm of toluene and changes in central nervous system function and symptoms. Paid subjects were exposed for seven hours over three days. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory); perception (pattern recognition); psychomotor skill (simple reaction time, continuous performance, digit symbol, hand-eye coordination, finger tapping, and critical tracking); manual dexterity (one hole); mood (profile of mood scales (POMS]; fatigue (fatigue checklist); and verbal ability were evaluated at 0800, 1200, and 1600 hours. Voluntary symptoms and observations of sleep were collected daily. An analysis of variance and test for trend was performed on the difference and score for each concentration reflecting an eight hour workday where each subject was their own control. A 3 x 3 Latin square study design evaluated toluene effects simultaneously, controlling for learning across the three days and the solvent order. Intersubject variation in solvent uptake was monitored in breath and urine. A 5-10% decrement in performance was considered significant if it was consistent with a linear trend at p less than 0.05. Adverse performance at 150 ppm toluene was found at 6.0% for digit span, 12.1% for pattern recognition (latency), 5.0% for pattern memory (number correct), 6.5% for one hole, and 3.0% for critical tracking. The number of headaches and eye irritation also increased in a dose response manner. The greatest effect was found for an increasing number of observations of sleep. Overall, no clear pattern of neurobehavioural effects was found consistent with the type 1 central nervous system as classified by the World Health Organisation. Subtle acute effects, however, were found just below and above the ACGIH TLV of 100 ppm toluene, supporting the position that the guideline be lowered since the biological

  6. Acute behavioural comparisons of toluene and ethanol in human subjects.

    OpenAIRE

    Echeverria, D; Fine, L; Langolf, G; Schork, T; Sampaio, C

    1991-01-01

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

  7. Toluene monooxygenase from the fungus Cladosporium sphaerospermum

    NARCIS (Netherlands)

    Luykx, D.M.A.M.; Prenafeta-Boldu, F.X.; Bont, de J.A.M.

    2003-01-01

    Assimilation of toluene by Cladosporium sphaerospermum is initially catalyzed by toluene monooxygenase (TOMO). TOMO activity was induced by adding toluene to a glucose-pregrown culture of C. sphaerospermum. The corresponding microsomal enzyme needed NADPH and O2 to oxidize toluene and glycerol,

  8. Review: Microbial degradation of toluene | Gopinath | African ...

    African Journals Online (AJOL)

    In spite of positive potential application, toluene results in many mishaps especially health hazards; hence amputation of toluene is crucial for human welfare as well as environmental issues. This review deals with destruction of toluene using microbial degradation. The overall aerobic biodegradation of toluene into carbon ...

  9. Information draft on the development of air standards for toluene

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-01-01

    Toluene is a colorless, volatile liquid with a benzene-like odour. Its predominant use is in the production of benzene, as an octane enhancer in gasoline, as a solvent in aerosol spray paints, wall paints, lacquers, inks, adhesives, resins, and in such consumer products as spot removers, paint strippers, cosmetics, perfumes and antifreezes. Approximately 150 Ontario industrial sources reported toluene releases to the air totaling 4,245 to 5,300 tonnes during the reporting years from 1993 to 1996, making toluene one of the top pollutants by release quantities in Ontario and Canada for all these years. It is absorbed via the lungs and the gastrointestinal tract, both in humans and animals. Once absorbed, it tends to accumulate in the fatty tissues, and in vascularized tissues such as nerve cells and brain tissue. Toluene adversely affects the central nervous system (CNS) of humans and experimental animals. Observed symptoms in exposed humans range from decrease in psychometric performance, to headache, intoxication, convulsions, narcosis and death. Health Canada concluded that toluene is unlikely to be carcinogenic, although the available data is insufficient for definite classification. Ontario has 24-hour ambient air quality criterion and a half-hour Point of Impingement standard for toluene of 2,000 microgram/cubic meter, based on odour effects. The US Environmental Protection Agency inhalation reference concentration (also adopted by most of the American states) is 400 microgram/cubic meter. The WHO recommended a guideline value of 7500 microgram/cubic meter. Health Canada And Environment Canada established a tolerable concentration of 3750 microgram/cubic meter. 69 refs., 2 tabs., appendix

  10. Toluene stability Space Station Rankine power system

    Science.gov (United States)

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

    1987-01-01

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

  11. Radiolysis of Aqueous Toluene Solutions

    International Nuclear Information System (INIS)

    Christensen, H.C.; Gustafson, R.

    1971-04-01

    Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N 2 O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N 2 O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H 2 ). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

  12. Toluene depresses plasma corticosterone in pregnant rats

    DEFF Research Database (Denmark)

    Hougaard, K. S.; Hansen, A. M.; Hass, Ulla

    2003-01-01

    of corticosteroids from the maternal to the foetal compartment. Pregnant rats were subjected to either 1500 ppm toluene 6 hr/day and/or a schedule of "Chronic mild stress" during the last two weeks of gestation. Exposure to toluene was associated with reduced birth weight and lower maternal weight gain, the latter...

  13. Alkylation of toluene with isopropyl alcohol over SAPO-5 catalyst

    Indian Academy of Sciences (India)

    cymene; isopropylation; toluene; SAPO-5. Abstract. Isopropylation of toluene with isopropyl alcohol was studied over the large pore silicon alumino phosphate molecular sieves (SAPO-5) with varying Si content. Toluene conversion was found ...

  14. Toluene depresses plasma corticosterone in pregnant rats

    DEFF Research Database (Denmark)

    Hougaard, Karin S; Hansen, Åse Marie; Hass, Ulla

    2003-01-01

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

  15. Anticonvulsant and antipunishment effects of toluene

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-01-01

    Toluene can have striking acute behavioral effects and is subject to abuse by inhalation. To determine if its actions resemble those of drugs used in the treatment of anxiety (anxiolytics), two sets of experiments were undertaken. Inasmuch as prevention of pentylenetetrazol-induced convulsions is an identifying property of this class of agents, the authors first demonstrated that pretreatment of mice with injections of toluene delayed the onset of convulsive signs and prevented the tonic extension phase of the convulsant activity in a dose-related manner. Injections of another alkyl benzene, m-xylene, were of comparable potency to toluene. Inhalation of toluene delayed the time of death after pentylenetetrazol injection in a manner related to the duration and concentration of exposure; at lower convulsant doses, inhalation of moderate concentrations (EC/sub 58/, 1300 ppm) prevented death. Treatment with a benzodiazepine receptor antagonist (Ro 15-1788) failed to reduce the anticonvulsant activity of inhaled toluene. Anxiolytics also attenuate the reduction in response rate produced by punishment with electric shock. Toluene increased rates of responding suppressed by punishment when responding was maintained under a multiple fixed-interval fixed-interval punishment schedule of reinforcement. Distinct antipunishment effects were observed in rats after 2 hr of exposure to 1780 and 3000 ppm of toluene; the rate-increasing effects of toluene were related to concentration and to time after the termination of exposure. Thus, toluene and m-xylene resemble in several respects clinically useful drugs such as the benzodiazepines. 51 references, 3 figures, 2 tables.

  16. Acute behavioural comparisons of toluene and ethanol in human subjects.

    Science.gov (United States)

    Echeverria, D; Fine, L; Langolf, G; Schork, T; Sampaio, C

    1991-11-01

    A comparison of toluene and ethanol (EtOH) induced changes in central nervous system (CNS) function and symptoms were evaluated in two studies, and when possible the effects of toluene were expressed in EtOH equivalent units. The toluene concentrations were 0, 75, and 150 ppm, bracketing the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) of 100 ppm. The socially relevant EtOH doses were 0.00, 0.33, and 0.66 g EtOH/kg body weight, equivalent to two and four 3.5% 12 ounce beers. Forty two paid college students were used in each study. In the first study, subjects were exposed to toluene and an odour masking agent menthol (0.078 ppm) for seven hours over three days. In the second study EtOH or a placebo was administered at 1530 across three days also in the presence of menthol. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory), perception (pattern recognition), psychomotor skill (simple reaction time, continuous performance, symbol-digit, hand-eye coordination, finger tapping, and critical tracking), manual dexterity (one hole), mood (profile on mood scales (POMS), fatigue (fatigue checklist), and verbal ability were evaluated at 0800, 1200, and 1600. Voluntary symptoms and observations of sleep were collected daily. A 3 x 3 latin square design evaluated solvent effects simultaneously controlling for learning and dose sequence. An analysis of variance and test for trend were performed on am-pm differences reflecting an eight hour workday and on pm scores for each solvent, in which subjects were their own control Intersubject variation in absorbance was monitored in breath. A 5 to 10% decrement was considered meaningful if consistent with a linear trend at p less than 0.05. At 150 ppm toluene, losses in performance were 6.0% for digit span, 12.1% for pattern recognition (latency), 5% for pattern memory (number correct), 6.5% for one hole, and 3% for critical tracking. The number of headaches

  17. Atmospheric oxidation mechanism of toluene.

    Science.gov (United States)

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

    2014-06-26

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

  18. Primary atmospheric oxidation mechanism for toluene.

    Science.gov (United States)

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

    2009-01-08

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

  19. Health assessment of toluene in California drinking water

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-03-08

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

  20. Mobility of Toluene in Polystyrene-Toluene Solutions: A NMR Study

    Science.gov (United States)

    1992-07-01

    FDB-25 Mobility of Toluene in Polystyrene-Toluene Solutions. A NMR Study. by Byaprorn naNagara, Robert D. O’Connor, and Frank D. Blum Department of...NUMBERS Mobility of Toluene in Polystyrene-Toluene Solutions. A NMR Study N00014-91-J-1274 6. AUTHOR(S) Byaporn naNagara, Robert D. O’Connor, Frank D. Blun... Stejskal and Tanner 26 yields an echo amplitude which is given by:4 ,5,26 ,27 X 2-2, 2) A = Ao f(A) ex _(-4- - (y8G) D(A-8/3) where A denotes the

  1. Human response to varying concentrations of toluene

    DEFF Research Database (Denmark)

    Bælum, Jesper; Lundqvist, G R; Mølhave, Lars

    1990-01-01

    Thirty two males and 39 females aged 31-50 were exposed for 7 h to one of the three following conditions: (1) Clean air, (2) constant exposure to 100 ppm toluene, or (3) a varying exposure with the same time-weighted average, but with peaks of 300 ppm every 30 min. During exposure the subjects ex...

  2. Chromatographic Determination of Toluene and its Metabolites in Urine for Toluene Exposure - A Review

    International Nuclear Information System (INIS)

    Mohamad Raizul Zinalibdin; Abdul Rahim Yacob; Mohd Marsin Sanagi

    2016-01-01

    The determinations of toluene and their metabolites in biological samples such as urine and blood allow the estimation of the degree of exposure to this chemical. Chromatographic methods and preliminary methods are now universally employed for this purpose. Preliminary color test methods are well established for qualitative determination of toluene and its metabolites. Mobile test kits using color test methods are a vast tool for screening urine samples but chromatographic methods are still needed for confirmation and quantitative analysis. Gas chromatography (GC) methods are well-adapted for the determination of toluene metabolite in urine, but these methods often require several pretreatment steps. Meanwhile, high performance liquid chromatography (HPLC) is becoming a powerful tool for the accurate and easy determination of toluene metabolites considering its decisive advantages for routine monitoring. Furthermore, recent development in HPLC could widen the usefulness of this method to solve the most complex analytical problems that could be encountered during the measurement. (author)

  3. Hepatic metabolism of toluene after gastrointestinal uptake in humans

    DEFF Research Database (Denmark)

    Bælum, Jesper; Mølhave, Lars; Honoré Hansen, S

    1993-01-01

    The metabolism of toluene and the influence of small doses of ethanol were measured in eight male volunteers after gastrointestinal uptake, the toluene concentration in alveolar air and the urinary excretion of hippuric acid and ortho-cresol being used as the measures of metabolism. During toluene...

  4. Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

    African Journals Online (AJOL)

    Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced ...

  5. Biodegradation and growth characteristics of a toluene-degrading ...

    African Journals Online (AJOL)

    A toluene-degrading strain was isolated from active sludge in this study. Both growth characteristic and the performance to degrade toluene by the strain in batch culture mode were evaluated. Results showed that the isolated strain presented a good ability to remove toluene with the maximum removal efficiency of 93.8%.

  6. Neurasthenic complaints and psychometric function of toluene-exposed rotogravure printers.

    Science.gov (United States)

    Orbaek, P; Nise, G

    1989-01-01

    In 1985, 30 rotogravure printers exposed to toluene for 4-43 years (median 29) were examined by means of interviews and psychometric testing. They were 33-61 years of age (mean 50). Comparisons were made with a reference group of 72 men aged 27-69 (mean 47). The referents had never been exposed to solvents and were all in good health. The printers were employed by two Swedish companies. The mean exposure levels were 43 and 157 mg/m3 of toluene, respectively, at the two printing shops. Before 1980 the exposure levels had exceeded 300 mg/m3. On Monday mornings, before psychometric testing at the department of occupational medicine, toluene was measured in venous blood samples from most of the exposed subjects. A high proportion of the printers reported fatigue (60%), recent short-term memory problems (60%), concentration difficulties (40%), mood lability (27%), and other neurasthenic symptoms. In the psychometric tests their performance was poorer than the reference group's in most of the tests applied. Even performance on the synonyms test, usually considered resistant to mild brain affliction, was worse in the group of printers. Adjusting for this difference in the group comparisons reduced the group differences substantially. Alcohol consumption above 200 g/week was found to reduce the subjects' psychometric function more than toluene exposure. The printers' sum of neurasthenic complaints correlated negatively with their score in several tests. Exposure variables showed only weak associations with test results. Blood toluene levels were positively correlated with scores in spatial tests. The direction of the correlations suggests that the influence of acute pharmacologic effects is undetectable on Monday mornings before work. In conclusion, we found that exposure to toluene at levels below 157 mg/m3 following long-term exposure did induce neurasthenic problems and might reduce psychometric test performance.

  7. ASSESSMENT OF HUMAN EXPOSURE TO TOLUENE DIISOCYANATE

    Directory of Open Access Journals (Sweden)

    OLIVIA ANCA RUSU

    2011-03-01

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

  8. Reassessing the atmospheric oxidation mechanism of toluene

    Science.gov (United States)

    Ji, Yuemeng; Zhao, Jun; Terazono, Hajime; Misawa, Kentaro; Levitt, Nicholas P.; Li, Yixin; Lin, Yun; Peng, Jianfei; Wang, Yuan; Duan, Lian; Pan, Bowen; Zhang, Fang; Feng, Xidan; An, Taicheng; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Zhang, Annie L.; Shibuya, Kazuhiko; Molina, Mario J.; Zhang, Renyi

    2017-08-01

    Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O2 to form the cresol proceeds with a smaller barrier than O2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

  9. Reassessing the atmospheric oxidation mechanism of toluene.

    Science.gov (United States)

    Ji, Yuemeng; Zhao, Jun; Terazono, Hajime; Misawa, Kentaro; Levitt, Nicholas P; Li, Yixin; Lin, Yun; Peng, Jianfei; Wang, Yuan; Duan, Lian; Pan, Bowen; Zhang, Fang; Feng, Xidan; An, Taicheng; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Zhang, Annie L; Shibuya, Kazuhiko; Molina, Mario J; Zhang, Renyi

    2017-08-01

    Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH ( ortho ) addition, the pathway of H extraction by O 2 to form the cresol proceeds with a smaller barrier than O 2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

  10. Detection of benzene, toluene, ethyl benzene, and xylenes (BTEX) using toluene dioxygenase-peroxidase coupling reactions.

    Science.gov (United States)

    Xu, Zhaohui; Mulchandani, Ashok; Chen, Wilfred

    2003-01-01

    We have developed a simple, whole-cell bioassay for the detection of bioavailable benzene, toluene, ethyl benzene, and xylenes (BTEX) and similar compounds. A genetically engineered E. coli strain expressing toluene dioxygenase (TDO) and toluene dihydrodiol dehydrogenase (TodD) was constructed, enabling the conversion of BTEX into their respective catechols, which were quickly converted into colored products by a horseradish peroxidase (HRP)-coupled reaction. The intensity of the color formation was correlated to concentrations of the BTEX compounds. Under the optimized conditions, a detection limit (defined as three times the standard deviation of the response obtained from the blank) of 10, 10, 20, and 50 microM was observed for benzene, toluene, ethyl benzene, and xylene, respectively. The bioassay was selective toward BTEX-related compounds with no interference observed with commonly used pesticides, herbicides, and organic solvent. The bioassay was very stable with little change in response over a 10-week period. The excellent stability suggests that the reported bioassay may be suitable for field monitoring of BTEX to identify and track contaminated water and follow the bioremediation progress.

  11. All rights reserved Competitive Adsorption of Xylene and Toluene on ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2018-03-23

    Mar 23, 2018 ... organic solvents (diesel, kerosene, gasoline, toluene and m-xylene), with and without agitation. The result showed that modified magnesium bentonite swelled more than the unmodified and the order of the swelling factor is; m- xylene > toluene > gasoline > diesel > DPK > water. However, when the assay ...

  12. Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced in the surfactant concentration less than critical micelle concentration. For the.

  13. Toluene removal in a biofilm reactor for waste gas treatment

    DEFF Research Database (Denmark)

    Pedersen, A.R.; Arvin, E.

    1997-01-01

    A lab-scale trickling filter for treatment of toluene-containing waste gas was investigated. The filter performance was investigated for various loads of toluene. Two levels of the gas flow were examined, 322 m d(-1) and 707 m d(-1). The gas inlet concentrations were varied in the range from 0...

  14. Alkylation of toluene with isopropyl alcohol over SAPO-5 catalyst

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Isopropylation of toluene with isopropyl alcohol was studied over the large pore silicon alu- mino phosphate molecular sieves (SAPO-5) with varying Si content. Toluene conversion was found to increase with increase in the Si of the catalysts. The effect of temperature on yields of cymene was studied in the range ...

  15. Cerebellar dysfunction caused by sniffing of toluene-containing thinner

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-01-01

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

  16. Laboratory diagnosis of toluene-based inhalants abuse.

    Science.gov (United States)

    Thiesen, Flavia Valladão; Noto, Ana Regina; Barros, Helena M T

    2007-01-01

    Toluene is the main substance contained in products used as inhalants. The frequent abuse of toluene-based inhalants requires the definition of a simple laboratory parameter that allows acute exposure assessment. This study aimed at defining urinary hippuric acid (UHA) levels related to intentional exposure to toluene, and to correlate them to blood toluene concentration (BT). BT and UHA levels were measured in 65 homeless adolescents of Porto Alegre, Brazil. Toluene was detected in 91.9% of the investigated population, who presented BT levels from 0.5 to 83.7 microg/mL. There was good correlation between UHA and BT concentrations (r = 0.78), and in homeless adolescents, UHA levels higher than 3.0 g/g creatinine indicate intentional exposure to toluene. The determination of UHA concentrations can be used as a screening method for the detection of intentional exposure to toluene, but its diagnosis must include BT toluene dosage, as well as circumstantial and clinical evidence.

  17. Active efflux of toluene in a solvent-resistant bacterium.

    OpenAIRE

    Isken, S; de Bont, J A

    1996-01-01

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

  18. Toluene inducing acute respiratory failure in a spray paint sniffer.

    Science.gov (United States)

    Peralta, Diego P; Chang, Aymara Y

    2012-01-01

    Toluene, formerly known as toluol, is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent. Like other solvents, toluene is sometimes also used as an inhalant drug for its intoxicating properties. It has potential to cause multiple effects in the body including death. I report a case of a 27-year-old male, chronic spray paint sniffer, who presented with severe generalized muscle weakness and developed acute respiratory failure requiring ventilatory support. Toluene toxicity was confirmed with measurement of hippuric acid of 8.0 g/L (normal <5.0 g/L). Acute respiratory failure is a rare complication of chronic toluene exposure that may be lethal if it is not recognized immediately. To our knowledge, this is the second case of acute respiratory failure due to toluene exposure.

  19. OH-initiated oxidation of toluene. 2. Master equation simulation of toluene oxide isomerization.

    Science.gov (United States)

    Frankcombe, Terry J; Smith, Sean C

    2007-05-17

    In this work we continue our investigation of the toluene-OH-O2 system. We describe master equation modeling of the isomerization of toluene oxide, focusing on the formation of the cresols. A 15 isomer model is used. Simulations of both thermally activated processes and photolysis processes are described. In accord with experiment, it is found that photolysis with a high-energy light source should be expected to give a high yield of the thermal distribution of cresol products (dominated by the para isomer). Photolysis with a low-energy light source, on the other hand, favors formation of the thermally disfavored ortho isomer. Though the 15 isomer system is potentially an excellent test bed for the development of scalable master equation solution methods, existing scalable solution methods were found to fail on this system.

  20. Effect of ethanol, cimetidine and propranolol on toluene metabolism in man

    DEFF Research Database (Denmark)

    Døssing, M; Bælum, Jesper; Hansen, S H

    1984-01-01

    In a climatic exposure chamber four healthy volunteers were exposed to 100ppm toluene, 100ppm toluene + ethanol, 100ppm toluene + cimetidine, and 100ppm toluene + propranolol for 7h each at random over four consecutive days. A control experiment and 3.5h of exposure to 200ppm toluene were also...... of exposure the increase was by 3.3. Neither cimetidine nor propranolol changed toluene metabolism significantly. The results indicate that ethanol may prolong the time interval in which toluene is retained in the human body in persons simultaneously exposed to ethanol and toluene. When using o...

  1. Unimolecular dissociation of doubly ionized toluene and electron transfer between neutral toluene and its dication

    Czech Academy of Sciences Publication Activity Database

    Shaffer, Christopher; Schröder, Detlef; Zins, E. L.; Alcaraz, Ch.; Žabka, Ján; Roithová, J.

    2012-01-01

    Roč. 534, 1 May (2012), s. 8-12 ISSN 0009-2614 R&D Projects: GA ČR GA203/09/1223; GA ČR GAP208/11/0446 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40400503 Keywords : dications * electron transfer * photoionization * toluene * synchrotron radiation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.145, year: 2012

  2. Preliminary response of a pristine aquifer when facing toluene contamination

    Science.gov (United States)

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

    2012-04-01

    Toluene is a common groundwater contaminant due to the wide spread of gasoline and industrial solvents. The understanding of how and when ecosystems initially respond to the presence of toluene is yet limited, because field investigations rarely start before a contamination has occurred. In order to investigate for the first time such a scenario, a pristine indoor aquifer model (0.8 - 0.7 - 5 m) was constructed, filled with natural sediment, flushed with natural groundwater at a rate of 9 L/hr, and subsequently exposed to a toluene contamination. Investigation was done to the chemical and biological parameters of the model, including oxygen concentration (9.6 mg/L), nitrate concentration (5.8 mg/L), small organic carbon content (0.8 mg/L), microbial abundance (4 x 104 cell/mL), and ATP (0.01 nM). This agreed with the condition of a typical pristine and oligotrophic aquifer. A 30-hr aqueous toluene pulse (water saturated with toluene) was injected into the system together with a conservative tracer (90% D2O). Water samples were collected 4.2 m away from the injection source. The comparison between the toluene and D2O breakthrough curves indicated that a portion of toluene was removed by degradation at a pseudo 1st order rate of 0.017/hr. Stable carbon isotope values of toluene were also measured along with the breakthrough curves. δ13C values were more positive than the original input, confirming that biodegradation had taken place. Subsequent to the pulse, a constant injection of aqueous toluene together with bromide was applied to obtain a deeper insight of the biological and geochemical processes in the aquifer. High resolution water sampling over the entire aquifer model was conducted 80 hrs after the start of constant injection. Microbial abundance and living biomass (ATP) were observed to be 10 - and 100 -, respectively, higher than under pristine conditions. Biodegradation was detected by comparing the concentration of toluene and bromide, and was confirmed

  3. Interactions between Asphaltenes and Water in Solutions in Toluene

    DEFF Research Database (Denmark)

    Khvostichenko, Daria; Andersen, Simon Ivar

    2008-01-01

    Binding of water by asphaltenes dissolved in toluene was investigated for two asphaltene samples, OMV1 and OMV2, from the same reservoir deposit. Solubility of water in asphaltene solutions in toluene was found to increase with an increasing asphaltene concentration, indicative of solubilization...... of water by asphaltenes. Fourier transform infrared (FTIR) spectroscopy of stretching modes of OH groups in the region of 3800-3100 cm(-1) was used to obtain insight into the state of water in water-unsaturated asphaltene solutions in toluene. The number of water molecules bound to one asphaltene molecule...... was determined for water-saturated solutions (OMV1 and OMV2) and for water-unsaturated solutions (OMV1 only). These numbers were found to decrease from several water molecules per asphaltene molecule to below unity upon an increase of the asphaltene concentration in toluene from 0.1 to 20 g/L, suggesting...

  4. Dynamics and the Regiochemistry of Nitration of Toluene

    OpenAIRE

    Nieves-Quinones, Yexenia; Singleton, Daniel A.

    2016-01-01

    The regiochemistry of the nitration of toluene by NO2+BF4− in dichloromethane is accurately predicted from trajectories in explicit solvent. Simpler models and approaches based on transition state theory fail to account for the selectivity. Potential of mean force calculations find no free-energy barrier for reaction of the toluene/NO2+BF4− encounter complex, yet the trajectories require an extraordinary 3 ps to descend an exergonic slope. The selectivity is decided late in long trajectories ...

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

    OpenAIRE

    Tsao, C.-W.; Song, H.-G.; Bartha, R.

    1998-01-01

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

  6. Atrioventricular conduction abnormality and hyperchloremic metabolic acidosis in toluene sniffing

    Directory of Open Access Journals (Sweden)

    Jian-Hsiung Tsao

    2011-10-01

    Full Text Available Toluene is an aromatic hydrocarbon with widespread industrial use as an organic solvent. As a result of the euphoric effect and availability of these substances, inhalation of toluene-based products is popular among young adults and children. Chronic or acute exposure is known to cause acid–base and electrolyte disorders, and to be toxic to the nervous and hematopoietic systems. We report a 38-year-old man who suffered from general muscular weakness of all extremities after toluene sniffing, which was complicated with hypokalemic paralysis, atrioventricular conduction abnormality, and normal anion gap hyperchloremic metabolic acidosis. Renal function, serum potassium and acid–base status normalized within 3 days after aggressive potassium chloride and intravenous fluid replacement. Electrocardiography showed regression of first-degree atrioventricular block. Exposure to toluene can lead to cardiac arrhythmias and sudden sniffing death syndrome. Tachyarrhythmia is the classical manifestation of toluene cardiotoxicity. Atrioventricular conduction abnormalities have been rarely mentioned in the literature. Knowledge of the toxicology and medical complications associated with toluene sniffing is essential for clinical management of these patients.

  7. Toluene diffusion and reaction in unsaturated Pseudomonas putida biofilms

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-20

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

  8. Influence of organobentonite structure on toluene adsorption from water solution

    Directory of Open Access Journals (Sweden)

    Nuria Vidal

    2012-12-01

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

  9. Audition and exhibition to toluene - a contribution for the theme

    Directory of Open Access Journals (Sweden)

    Kulay, Luiz Alexandre

    2012-01-01

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

  10. Radioluminescence quenching of toluene scintillators by methyl methacrylate

    International Nuclear Information System (INIS)

    Polacki, Z.

    1985-01-01

    It was established that singlet electronic excited state of toluene is quenched by methyl methacrylate (MMA) but not by PMMA. The value of quenching rate constant ksub(q)=0,6x10sup(9) 1.molsup(-1).ssup(-1) indicates that the quenching is a diffusion controlled process. It is assumed that the excitation energy of toluene sensitizes the polymerization process of MMA. The increase of radioluminescence intensity and quantum yield of excitation energy transfer is the result of diminishing the quantity of MMA in the solution during polymerization time. (author)

  11. Dynamics and the Regiochemistry of Nitration of Toluene.

    Science.gov (United States)

    Nieves-Quinones, Yexenia; Singleton, Daniel A

    2016-11-23

    The regiochemistry of the nitration of toluene by NO 2 + BF 4 - in dichloromethane is accurately predicted from trajectories in explicit solvent. Simpler models and approaches based on transition state theory fail to account for the selectivity. Potential of mean force calculations find no free-energy barrier for reaction of the toluene/NO 2 + BF 4 - encounter complex, yet the trajectories require an extraordinary 3 ps to descend an exergonic slope. The selectivity is decided late in long trajectories because their completion requires solvent and counterion reorganization. The normal descriptive understanding of the regiochemistry based on transition-state energies is unsupported.

  12. Antipyrine clearance during experimental and occupational exposure to toluene

    DEFF Research Database (Denmark)

    Døssing, M; Bælum, Jesper; Lundqvist, G R

    1983-01-01

    Exposure to toluene vapour enhances hepatic microsomal enzyme function in animals as assessed by the metabolism of the test drug antipyrine. Thirty six printing trade workers with long term occupational exposure to a mixture of organic solvents and 39 matched controls were randomly allocated...... clearance 12 printing trade workers with 17 years (median) of occupational exposure to toluene vapour at concentrations of about 100 ppm were investigated before and four weeks after cessation of exposure. No difference in antipyrine clearance was found either within the groups or between the groups at any...

  13. FORMATION OF POLYKETONES IN IRRADIATED TOLUENE/PROPYLENE/NOX/AIR MIXTURES

    Science.gov (United States)

    A laboratory study was carried out to investigate the formation of polyketones in secondary organic aerosol from photooxidation of the aromatic hydrocarbon toluene, a major constituent of automobile exhaust. The laboratory experiments consisted of irradiating toluene/propylene...

  14. Metabolic interaction between toluene, trichloroethylene and n-hexane in humans

    DEFF Research Database (Denmark)

    Bælum, Jesper; Mølhave, Lars; Hansen, S H

    1998-01-01

    This human experimental study describes the mutual metabolic interaction between toluene, trichloroethylene, and n-hexane.......This human experimental study describes the mutual metabolic interaction between toluene, trichloroethylene, and n-hexane....

  15. Modelling toluene oxidation : Incorporation of mass transfer phenomena

    NARCIS (Netherlands)

    Hoorn, J.A.A.; van Soolingen, J.; Versteeg, G. F.

    The kinetics of the oxidation of toluene have been studied in close interaction with the gas-liquid mass transfer occurring in the reactor. Kinetic parameters for a simple model have been estimated on basis of experimental observations performed under industrial conditions. The conclusions for the

  16. Electrocardiographic effects of toluene in the anesthetized rat.

    Science.gov (United States)

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

    1986-01-01

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

  17. Fenton-like initiation of a toluene transformation mechanism

    Science.gov (United States)

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

  18. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Administrator

    phenols, fragrances, pharmaceuticals, herbicides, heat transfer media, etc. The alkylation of toluene over zeolites is normally considered to follow the well-known Friedel–Crafts mechanism which evidently proceeds by direct ortho-para attack of the ring followed by positional isomerisation producing the meta isomer. 1,2.

  19. Effects of Toluene on Some Physicochemical Parameters of The ...

    African Journals Online (AJOL)

    Reproductive success analysis showed a decrease in hatching success across the concentrations and high mortality of eggs with increased concentration. The control had 36.6% hatching success, while ... treated before released into the environment. Keywords: effect, toluene, catfish, growth, reproductive, performance.

  20. 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)

  1. PHOSPHOLIPIDS OF FIVE PSEUDOMONAD ARCHETYPES FOR DIFFERENT TOLUENE DEGRADATION PATHWAYS

    Science.gov (United States)

    Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine phospholipid profiles for five reference pseudomonad strains harboring distinct toluene catabolic pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, B...

  2. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Mordenite (HM) catalysts with three different Si/Al ratios were compared for their activity and selectivities in gas phase toluene isopropylation with isopropanol. Catalyst with Si/Al ratio 44.9 offered better cumene selectivity, hence, it was chosen for detailed kinetic investigations. The influence of various process parameters ...

  3. Isolation and characterization of a novel toluene-degrading, sulfate-reducing bacterium.

    OpenAIRE

    Beller, H R; Spormann, A M; Sharma, P K; Cole, J R; Reinhard, M

    1996-01-01

    A novel sulfate-reducing bacterium isolated from fuel-contaminated subsurface soil, strain PRTOL1, mineralizes toluene as the sole electron donor and carbon source under strictly anaerobic conditions. The mineralization of 80% of toluene carbon to CO2 was demonstrated in experiments with [ring-U-14C]toluene; 15% of toluene carbon was converted to biomass and nonvolatile metabolic by-products, primarily the former. The observed stoichiometric ratio of moles of sulfate consumed per mole of tolu...

  4. Tentative criteria for assessing workers exposure to toluene by urinary toluene screening.

    Science.gov (United States)

    Asakawa, Fumiyuki; Hirao, Tomohiro; Suna, Shigeru; Kureha, Akinori; Jitsunari, Fumihiko

    2006-04-01

    This study assessed screening thresholds for determining workers exposure to toluene (Tol) by urinary Tol (Tol-U) and proposed applicable criteria for on-site settings. Participants' urine samples (n = 21) were collected at the end of the workday during the latter half of a week and the Tol-U concentration was assayed. Simultaneously, each worker's exposure dose to Tol in the breathing zone during work, Tol-TWA (time-weighted average), was measured. Tentative criteria were proposed. Level I, less than Tol-U 38 microg/l, has the least chance of exceeding Tol-OEL 50 ppm (occupational exposure limit for Tol recommended by the Japan Society for Occupational Health), probability 95% <. Level II, Tol-U 38-60 microg/l, has a low possibility of exceeding Tol-OEL. Level III, Tol-U 60-110 microg/l, has a high possibility of exceeding Tol-OEL. Level IV, more than Tol-U 110 microg/l, clearly exceeds Tol-OEL, probability 95% <.

  5. Transport and biodegradation of toluene in unsaturated soil

    Science.gov (United States)

    Jin, Yan; Streck, Thilo; Jury, William A.

    1994-12-01

    Degradation of volatile organic chemicals during transport has received little attention in the past. In this study we report the results of a series of experiments on toluene movement through soil columns of different length in sterilized, pre-exposed and unexposed soil. Toluene was added to 25-cm-diameter soil columns through an inlet chamber that maintained a constant concentration throughout the experiment. The toluene diffused through the soil to an outlet chamber at the top which was continuously swept with humidified air and samples were periodically analysed to determine toluene flux. The first experiment, conducted under sterilized conditions, was used to measure the soil gas diffusion coefficient, and subsequent experiments in which biodegradation occurred were used to estimate the degradation rate coefficient by fitting the outflow to a mathematical model. The degradation rate was very rapid under both pre-exposed and unexposed soil conditions, corresponding to a half-life of ˜ 2 h when bacterial activity reached high levels. Prior to this stage, the volatilization flux was very erratic, implying that growth rates of the bacteria were out of phase with the transport process. Overall, the degradation process was not well described by a first-order model until the population stabilized. Pre-exposure of the soil to the substrate prior to the transport experiment greatly increased the rate of removal of toluene during transport. Under such conditions, a 30-cm cover could virtually stop volatization losses of the compound when the inlet concentration was well below saturation, and could decrease it by a factor of ⩾30 even when the inlet concentration was saturated.

  6. Immunologic and renal markers among photogravure printers exposed to toluene.

    Science.gov (United States)

    Stengel, B; Cénée, S; Limasset, J C; Diebold, F; Michard, D; Druet, P; Hémon, D

    1998-08-01

    This study assessed immunologic and early renal effects of chronic toluene exposure. In a longitudinal study of 92 printers and 74 referents, 145 subjects had pre- and poststudy samples of blood and urine taken for the following measurements: immunoglobulin E (IgE), antiglomerular basement membrane (anti-GBM) and antilaminin (anti-LAM) antibodies in blood; creatinine and beta2-microglobulin in blood and urine; and microalbumin, N-acetyl-b-D-glucosaminidase (NAG) and alanine-aminopeptidase in urine. Creatinine clearance was calculated according to the Cockroft-Gault formula. Eight-hour personal air samples were collected twice to assess present exposure to toluene. A job-exposure matrix was developed to estimate past cumulative exposure. Information about potential confounders was recorded by questionnaire. Multiple regression analysis was performed to study dose-effect relations adjusted for age and smoking. No subject was positive for anti-GBM antibodies, and only 12 were positive for anti-LAM. No relation was observed between the markers studied and present exposure to toluene except that creatinine clearance was higher among the exposed subjects than among the referents. A dose-response relation was observed between cumulative toluene exposure and both IgE and NAG excretion. No interaction was observed between hypertension and exposure, but the relationship with NAG did not persist when subjects with hypertension were excluded. Past or present exposure did not alter the 2-year trend of any marker studied. According to the results of this study, toluene at 50 ppm is not related to detectable renal dysfunction. The increased IgE levels associated with present and past exposure require further investigation.

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

    NARCIS (Netherlands)

    Volkers, R.J.M.; Ballerstedt, H.; Ruijssenaars, H.; Bont, J.A.M. de; Winde, J.H. de; Wery, J.

    2009-01-01

    Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent

  8. Medical Monitoring for Occupational Asthma Among Toluene Diisocyanate Production Workers in the United States.

    Science.gov (United States)

    Cassidy, Laura D; Doney, Brent; Wang, Mei Lin; Kurth, Laura; Conner, Patrick R; Collins, James J; Carson, Michael; Molenaar, Don; Redlich, Carrie A; Storey, Eileen

    2017-12-01

    The aim of this study was to describe a study of medical monitoring methods and lessons learned in detecting health outcomes in U.S. plants producing toluene diisocyanate (TDI). A multidisciplinary team implemented a medical and environmental monitoring program in three TDI plants. Of 269 eligible workers, 197 (73%) participated and 42 (21%) met symptom and/or lung function criteria that would trigger evaluation for possible asthma over 5 years of data collection. Subsequent evaluation was delayed for most, and a web-based data collection system improved timeliness. Medical monitoring of TDI workers identified workers triggering further assessment per study protocol. Systems and/or personnel to ensure rapid follow-up are needed to highlight when triggering events represent potential cases of asthma needing further evaluation. Implementation of a research protocol requires resources and oversight beyond an occupational health program.

  9. Modelling of toluene biodegradation and biofilm growth in a fixed biofilm reactor

    DEFF Research Database (Denmark)

    Arcangeli, Jean-Pierre; Arvin, Erik

    1992-01-01

    which grow relatively fast and detach easily, leading to a biomass growth delayed with respect to substrate degradation. The non-filamentous bacteria inside the biofilm also degrade toluene but with a slower rate compared to the filamentous bacteria. Because the nonfilamentous bacteria do not detach...... with toluene degradation was successfully modelled as well as the decay phase when toluene addition was turned off. In addition to this, modelling of toluene removal and oxygen consumption versus toluene concentration in the reactor was performed. This required consideration of inhibition of substrate...

  10. A new condensed toluene mechanism for Carbon Bond: CB05-TU

    Science.gov (United States)

    Whitten, Gary Z.; Heo, Gookyoung; Kimura, Yosuke; McDonald-Buller, Elena; Allen, David T.; Carter, William P. L.; Yarwood, Greg

    2010-12-01

    Toluene is ubiquitous in urban atmospheres and is a precursor to tropospheric ozone and aerosol (smog). An important characteristic of toluene chemistry is the tendency of some degradation products (e.g., cresols and methyl-catechols) to form organic nitro and nitrate compounds that sequester NOx (NO and NO 2) from active participation in smog formation. Explaining the NOx sinks in toluene degradation has made mechanism development more difficult for toluene than for many other organic compounds. Another challenge for toluene is explaining sources of radicals early in the degradation process. This paper describes the development of a new condensed toluene mechanism consisting of 26 reactions, and evaluates the performance of CB05 with this new toluene scheme (Toluene Update, TU) against 38 chamber experiments at 7 different environmental chambers, and provides recommendations for future developments. CB05 with the current toluene mechanism (CB05-Base) under-predicted the maximum O 3 and O 3 production rate for many of these toluene-NOx chamber experiments, especially under low-NOx conditions ([NOx] t=0 toluene mechanism (CB05-TU) includes changes to the yields and reactions of cresols and ring-opening products, and showed better performance than CB05-Base in predicting the maximum O 3, O 3 formation rate, NOx removal rate and cresol concentration. Additional environmental chamber simulations with xylene-NOx experiments showed that the TU mechanism updates tended to improve mechanism performance for xylene.

  11. The function of a toluene-degrading bacterial community in a waste gas trickling filter

    DEFF Research Database (Denmark)

    Pedersen, A.R.; Arvin, E.

    1999-01-01

    ) during two weeks. In spite of the low fraction in the biofilm, the toluene degraders supported growth of the dominating part of non-toluene-degrading heterotrophs in the biofilm, as toluene was the sole carbon source supplied to the system. The maximum intrinsic growth rate of P. putida in the biofilm......The function of a community of toluene-degrading bacteria in a biofilm system was investigated with regard to growth and toluene degradation in order to investigate substrate interactions in the community. This was done by the combination of experimental observations using a specific...... and the activity of P. putida, a representative of the toluene-degrading species in the biofilm which have been described previously (Pedersen et al., 1997) were simulated. The simulation indicated that the volume fraction of the toluene degraders in the biofilm decreased from 12% to only 2% (11% of dry weight...

  12. Toluene metabolism during exposure to varying concentrations combined with exercise

    DEFF Research Database (Denmark)

    Bælum, Jesper; Døssing, M; Hansen, S H

    1987-01-01

    . In Study A, four males were exposed to clean air and to constant and varying concentrations of toluene in combination with rest and with 100 W exercise in 140 min. Exercise increased end exposure excretion rate of HA and O-cr by 47 and 114%, respectively. After exposure, all excess HA was excreted within 4...... between the exposure schedules. In Study B, 32 males and 39 females aged between 31 and 50 years were exposed once to either clean air, constant or varying concentrations of toluene. Background excretion rate of HA was 0.97 +/- 0.75 mg/min (1.25 +/- 1.05 g/g creatinine) and rose to 3.74 +/- 1.40 mg/min (3...... implementing either of them as biological exposure indices, the influence of sex, body size, age as well as consumption of tobacco and alcohol has to be considered....

  13. Rare earth(3) nitrates extraction with trialkylmethylammonium nitrate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kovalev, S.V.; Keskinov, V.A.; Khokhlova, N.V.

    1997-01-01

    Extraction of rare earth(3) nitrates [praseodymium(3)-lutetium(3)] with trialkylmethylammonium nitrate in toluene at T = 298.15 K and pH 2 is studied. Extraction isotherms are described with regard to formation of compounds of (R 4 N) i [Ln(NO 3 ) 3+i ] composition (i = 2, 3) in organic phase. Values of extraction constants are calculated, they are decreasing in the praseodymium(3) - lutetium(3) series

  14. Eco friendly nitration of toluene using modified zirconia

    Directory of Open Access Journals (Sweden)

    K.R. Sunaja Devi

    2013-03-01

    Full Text Available Nitration of toluene has been studied in the liquid phase over a series of modified zirconia catalysts.  Zirconia, zirconia- ceria (Zr0.98Ce0.02O2, sulfated zirconia and sulfated zirconia- ceria were synthesised by co precipitation method and were characterised by X-ray diffraction, BET surface area, Infra red spectroscopy analysis (FTIR, Thermogravimetric analysis (TGA, Scanning Electron Microscopy (SEM and Energy Dispersive X ray analysis (EDAX. The acidity of the prepared catalysts was determined by FTIR pyridine adsorption study. X-ray diffraction studies reveal that the catalysts prepared mainly consist of tetragonal phase with the crystallite size in the nano range and the tetragonal phase of zirconia is stabilized by the addition of ceria. The modified zirconia samples have higher surface area and exhibits uniform pore size distribution aggregated by zirconia nanoparticles. The onset of sulfate decomposition was observed around 723 K for sulfated samples. The catalytic performance was determined for the liquid phase nitration of toluene to ortho-, meta- and para- nitro toluene. The effect of reaction temperature, concentration of nitric acid, catalyst reusability and reaction time was also investigated. © 2013 BCREC UNDIP. All rights reservedReceived: 20th November 2012; Revised: 8th December 2012; Accepted: 7th January 2013[How to Cite: K. R. S. Devi, S. Jayashree, (2013. Eco friendly nitration of toluene using modified zirconia. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 205-214. (doi:10.9767/bcrec.7.3.4154.205-214][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4154.205-214 ] View in  |

  15. Deaths and tumours among rotogravure printers exposed to toluene.

    Science.gov (United States)

    Svensson, B G; Nise, G; Englander, V; Attewell, R; Skerfving, S; Möller, T

    1990-01-01

    A cohort of 1020 rotogravure printers exposed to toluene and employed for a minimum period of three months in eight plants during 1925-85 was studied. Air levels of toluene were available since 1943 in one plant and since 1969 in most. Based on these measurements and on present concentrations of toluene in blood and subcutaneous fat, the yearly average air levels in each plant were estimated. They reached a maximum of about 450 ppm in the 1940s and 1950s but were only about 30 ppm by the mid-1980s. Exposure to benzene had occurred up to the beginning of the 1960s. Compared with regional rates, total mortality did not increase during the observation period 1952-86 (129 observed deaths v 125 expected; SMR = 1.03). There was no increase in mortality from non-malignant diseases of the lungs, nervous system, or gastrointestinal and urinary tracts. There was no overall excess of tumours 1958-85 (68 v 54, SMR = 1.26; 95% confidence interval, CI = 0.95-1.7). Among the specific cancers, only those of the respiratory tract were significantly increased (16 v 9; SMR = 1.76, CI = 1.03-2.9). Statistical significance was not attained, however, when only subjects with an exposure period of at least five years and a latency period of at least 10 years were considered. Further, there were no dose response relations with cumulated toluene dose (ppm years). There were no significant increases of tumours at other sites, including leukaemias/lymphomas/myelomas. PMID:2378814

  16. Ignition studies of n-heptane/iso-octane/toluene blends

    KAUST Repository

    Javed, Tamour

    2016-07-09

    Ignition delay times of four ternary blends of n-heptane/iso-octane/toluene, referred to as Toluene Primary Reference Fuels (TPRFs), have been measured in a high-pressure shock tube and in a rapid compression machine. The TPRFs were formulated to match the research octane number (RON) and motor octane number (MON) of two high-octane gasolines and two prospective low-octane naphtha fuels. The experiments were carried out over a wide range of temperatures (650–1250 K), at pressures of 10, 20 and 40 bar, and at equivalence ratios of 0.5 and 1.0. It was observed that the ignition delay times of these TPRFs exhibit negligible octane dependence at high temperatures (T > 1000 K), weak octane dependence at low temperatures (T < 700 K), and strong octane dependence in the negative temperature coefficient (NTC) regime. A detailed chemical kinetic model was used to simulate and interpret the measured data. It was shown that the kinetic model requires general improvements to better predict low-temperature conditions and particularly requires improvements for high sensitivity (high toluene concentration) TPRF blends. These datasets will serve as important benchmark for future gasoline surrogate mechanism development and validation. © 2016 The Combustion Institute

  17. Toluene nitration in irradiated nitric acid and nitrite solutions

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Gracy, E-mail: gracy.elias@inl.go [Idaho National Laboratory, Chemical and Radiation Measurement Department, P.O. Box 1625, Idaho Falls, ID 83415-2213 (United States); Mincher, Bruce J. [Idaho National Laboratory, Aqueous Separations and Radiochemistry Department, P.O. Box 1625, Idaho Falls, ID 83415-6180 (United States); Mezyk, Stephen P. [California State University-Long Beach, Department of Chemistry and Biochemistry, 1250 Bellflower Boulevard, Long Beach, CA 90840-3903 (United States); Muller, Jim [University of Utah, Department of Chemistry, Salt Lake City, UT 84112-0850 (United States); Martin, Leigh R. [Idaho National Laboratory, Aqueous Separations and Radiochemistry Department, P.O. Box 1625, Idaho Falls, ID 83415-6180 (United States)

    2011-04-15

    The kinetics, mechanisms, and stable products produced for the nitration of aryl alkyl mild ortho-para director toluene in irradiated nitric acid and neutral nitrite solutions were investigated using {gamma} and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection, GC-MS and LC-MS, were used to assess the stable reaction products. Free-radical based nitration reaction products were found in irradiated acidic and neutral media. In 6.0 M HNO{sub 3}, ring substitution, side chain substitution, and oxidation, produced different nitrated toluene products. For ring substitution, nitrogen oxide radicals were added mainly to cyclohexadienyl radicals, whereas for side chain substitution, these radicals were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite solutions, radiolytically-induced ring nitration products approached a statistically random distribution, suggesting a direct free-radical reaction involving addition of the {sup {center_dot}N}O{sub 2} radical.

  18. Toluene nitration in irradiated nitric acid and nitrite solutions

    Science.gov (United States)

    Elias, Gracy; Mincher, Bruce J.; Mezyk, Stephen P.; Muller, Jim; Martin, Leigh R.

    2011-04-01

    The kinetics, mechanisms, and stable products produced for the nitration of aryl alkyl mild ortho-para director toluene in irradiated nitric acid and neutral nitrite solutions were investigated using γ and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection, GC-MS and LC-MS, were used to assess the stable reaction products. Free-radical based nitration reaction products were found in irradiated acidic and neutral media. In 6.0 M HNO3, ring substitution, side chain substitution, and oxidation, produced different nitrated toluene products. For ring substitution, nitrogen oxide radicals were added mainly to cyclohexadienyl radicals, whereas for side chain substitution, these radicals were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite solutions, radiolytically-induced ring nitration products approached a statistically random distribution, suggesting a direct free-radical reaction involving addition of the rad NO2 radical.

  19. Toluene nitration in irradiated nitric acid and nitrite solution

    Energy Technology Data Exchange (ETDEWEB)

    Gracy Elias; Bruce J. Mincher; Stephen P. Mezyk; Jim Muller; Leigh R. Martin

    2011-04-01

    The kinetics, mechanisms, and stable products produced for the aryl alkyl mild ortho-para director - toluene, in irradiated nitric acid and neutral nitrite solutions were investigated using ?, and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection was primarily used to assess the stable reaction products. GC-MS and LC-MS were used to confirm the results from HPLC. Free-radical nitration reaction products were found in irradiated acidic and neutral media. In acidic medium, the ring substitution and side chain substitution and oxidation produced different nitro products. In ring substitution, nitrogen oxide radicals were added mainly to hydroxyl radical-produced cyclohexadienyl radical, and in side chain substitution they were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite toluene solution, radiolytic ring nitration products approached a statistically random distribution, suggesting a free-radical reaction involving addition of the •NO2 radical.

  20. Toluene nitration in irradiated nitric acid and nitrite solutions

    International Nuclear Information System (INIS)

    Elias, Gracy; Mincher, Bruce J.; Mezyk, Stephen P.; Muller, Jim; Martin, Leigh R.

    2011-01-01

    The kinetics, mechanisms, and stable products produced for the nitration of aryl alkyl mild ortho-para director toluene in irradiated nitric acid and neutral nitrite solutions were investigated using γ and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection, GC-MS and LC-MS, were used to assess the stable reaction products. Free-radical based nitration reaction products were found in irradiated acidic and neutral media. In 6.0 M HNO 3 , ring substitution, side chain substitution, and oxidation, produced different nitrated toluene products. For ring substitution, nitrogen oxide radicals were added mainly to cyclohexadienyl radicals, whereas for side chain substitution, these radicals were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite solutions, radiolytically-induced ring nitration products approached a statistically random distribution, suggesting a direct free-radical reaction involving addition of the · NO 2 radical.

  1. Visual evoked potentials in rotogravure printers exposed to toluene.

    Science.gov (United States)

    Urban, P; Lukás, E

    1990-01-01

    Visual evoked potentials (VEPs) from stimulation by checkerboard pattern reversal were examined in 54 rotogravure printers exposed to toluene (all men, aged 22-64 years, duration of exposure 1-41 years). A control group consisted of 46 subjects (23 men and 23 women; aged 22-54 years). Compared with controls the exposed group showed more frequent responses with reduced reproducibility or absence of some waves, or both; the mean P1 wave latency was prolonged and mean amplitudes N1P1 and P1N2 were reduced. The VEPs were abnormal in 24% of workers. The frequency of abnormal VEPs correlated positively with the duration of exposure to toluene and also with the degree of alcohol drinking. No association was found between measurements of VEP and electroencephalogram (EEG) or electromyogram (EMG) examinations. A VEP measurement was made in 78% of the exposed workers two years after the first examination. No statistically significant difference between the two results was found. This suggests a marked stability of the observed VEP changes. These changes can be interpreted as a subclinical sign of dysfunction of the central nervous system (CNS) related to exposure to toluene and also to alcohol consumption. PMID:2271388

  2. Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts

    KAUST Repository

    Alabi, Wahab

    2012-07-01

    A kinetic study of toluene alkylation with methanol was performed over pure HZSM-5, mordenite/ZSM-5 (hybrid of mordenite and HZSM-5), and ZM13 (composite mixture of HZSM-5 and MCM-41 at pH 13). Experimental runs were conducted using a batch fluidized bed reactor at temperatures of 300, 350 and 400 °C and reaction times of 3, 5, 7, 10, 13, 15 and 20. s. The rate of toluene methylation and toluene disproportionation were studied on the three catalysts (toluene alkylation is usually accompanied by toluene disproportionation on acid catalyst). Based on the results obtained, a simplified power law kinetic model consisting of three reactions was developed to estimate the activation energies of toluene methylation and disproportionation simultaneously. Coke formation on catalysts was accounted for using both reaction time and reactant conversion decay functions. All parameters were estimated based on quasi-steady state approximation. Estimated kinetic parameters were in good agreement with experimental results. The order of alkylation ability of the catalysts was found to be ZM13 > HZSM-5 > mordenite/ZSM-5, while the reverse is for toluene disproportionation (mordenite/ZSM-5 > HZSM-5 > ZM13). Thus, alkylation of toluene is most favorable on ZM13 due to combined effect of mesoporosity induced through its synthetic route and acid content. Toluene/MeOH molar ratio of 1:1 was most suitable for toluene alkylation reaction. © 2012 Elsevier B.V.

  3. Induction of resistance to X-rays in E. coli by toluene

    International Nuclear Information System (INIS)

    Gillies, N.E.; Ratnajothi, N.H.

    1980-01-01

    Incubation of unirradiated bacteria with 10 M toluene in buffer for 30 min at 22 0 C did not affect their viability. When E. Coli K12AB1157 were incubated in buffer/toluene (10 M) for 30 min and then X-irradiated under either aerobic or anaerobic conditions in the presence of toluene the derived curves contained large shoulders; the Dsub(q) values were calculated to be 271 Gy and 921 Gy for bacteria irradiated under oxic and anoxic conditions respectively. The final exponential slopes for both curves were less steep than those for the strictly exponential curves obtained for X-irradiated bacteria which had neither been pre-incubated with toluene nor X-irradiated in the presence of toluene. When bacteria were exposed to toluene during the time of X-irradiation only, exponential survival curves were observed with slopes approximately the same as the terminal slopes of the curves for the bacteria pretreated and irradiated in the presence of toluene. When the bacteria were exposed initially to X-rays and then incubated with toluene, the survival curves were identical to those obtained for bacteria untreated with toluene. Survival after U.V. irradiation was the same whether or not the bacteria were treated with toluene before exposure to U.V. The modification of radioresistance by toluene appeared to be independent of the presence of oxygen at the time of irradiation. It is suggested that toluene does not effect the primary fixation of lesions, but may influence their subsequent removal. (U.K.)

  4. Physical properties of (propyl propanoate + hexane + toluene) at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Freire, S. [Departamento de Fisica, Facultade de Ciencias, Universidade da Coruna, 15071 A Coruna (Spain)]. E-mail: sfreire@udc.es; Segade, L. [Departamento de Fisica, Facultade de Ciencias, Universidade da Coruna, 15071 A Coruna (Spain); Cabeza, O. [Departamento de Fisica, Facultade de Ciencias, Universidade da Coruna, 15071 A Coruna (Spain); Jimenez, E. [Departamento de Fisica, Facultade de Ciencias, Universidade da Coruna, 15071 A Coruna (Spain)

    2007-04-15

    The aim of this paper is to report experimental densities, excess molar enthalpies and refractive indexes of the ternary system (propyl propanoate + hexane + toluene) and of the corresponding binary mixtures (propyl propanoate + toluene) and (hexane + toluene) at the temperature 298.15 K and atmospheric pressure, over the whole composition range. Also, the excess molar volumes and the changes in the refractive index on mixing have been calculated from the measured data for all mixtures.

  5. Toluene and benzyl decomposition mechanisms: elementary reactions and kinetic simulations.

    Science.gov (United States)

    Derudi, Marco; Polino, Daniela; Cavallotti, Carlo

    2011-12-28

    The high temperature decomposition kinetics of toluene and benzyl were investigated by combining a kinetic analysis with the ab initio/master equation study of new reaction channels. It was found that similarly to toluene, which decomposes to benzyl and phenyl losing atomic hydrogen and methyl, also benzyl decomposition proceeds through two channels with similar products. The first leads to the formation of fulvenallene and hydrogen and has already been investigated in detail in recent publications. In this work it is proposed that benzyl can decompose also through a second decomposition channel to form benzyne and methyl. The channel specific kinetic constants of benzyl decomposition were determined by integrating the RRKM/master equation over the C(7)H(7) potential energy surface. The energies of wells and saddle points were determined at the CCSD(T) level on B3LYP/6-31+G(d,p) structures. A kinetic mechanism was then formulated, which comprises the benzyl and toluene decomposition reactions together with a recently proposed fulvenallene decomposition mechanism, the decomposition kinetics of the fulvenallenyl radical, and some reactions describing the secondary chemistry originated by the decomposition products. The kinetic mechanism so obtained was used to simulate the production of H atoms measured in a wide pressure and temperature range using different experimental setups. The calculated and experimental data are in good agreement. Kinetic constants of the new reaction channels here examined are reported as a function of temperature at different pressures. The mechanism here proposed is not compatible with the assumption often used in literature kinetic mechanisms that benzyl decomposition can be effectively described through a lumped reaction whose products are the cyclopentadienyl radical and acetylene.

  6. Tricarbonylbis(tricyclohexylphosphine-κPruthenium(0 toluene solvate

    Directory of Open Access Journals (Sweden)

    Andreas Nader

    2008-11-01

    Full Text Available The title compound, [Ru(C18H33P2(CO3]·C7H8, shows a distorted trigonal-bipyramdial coordination around the central Ru atom, with the two phosphine ligands occupying the axial positions. Two toluene molecules per asymmetric unit with site-occupation factors of 0.5 are observed. One of them forces two of the CO ligands to enclose a wider C—Ru—C bond angle [127.5 (3°] than in the solvent-free crystal structure of [Ru(PCy32(CO3] (Cy is cyclohexyl.

  7. Characterization of toluene metabolism by methanotroph and its effect on methane oxidation.

    Science.gov (United States)

    He, Ruo; Su, Yao; Ma, Ruo-Chan; Zhuang, Shulin

    2018-04-03

    Methanotrophs not only oxidize CH 4 , but also can oxidize a relatively broad range of other substrates, including trichloroethylene, alkanes, alkenes, and aromatic compounds. In this study, Methylosinus sporium was used as a model organism to characterize toluene metabolism by methanotrophs. Reverse transcription quantitative PCR analysis showed that toluene enhanced the mmoX expression of M. sporium. When the toluene concentration was below 2000 mg m -3 , the kinetics of toluene metabolism by M. sporium conformed to the Michaelis-Menten equation (V max  = 0.238 g g dry weight -1  h -1 , K m  = 545.2 mg m -3 ). The use of a solid-phase extraction technique followed by a gas chromatography-mass spectrometry analysis and molecular docking calculation showed that toluene was likely to primarily bind the di-iron center structural region of soluble methane monooxygenase (sMMO) hydroxylase and then be oxidized to o-cresol. Although M. sporium oxidized toluene, it did not incorporate toluene into its biomass. The coexistence of toluene and CH 4 could influence CH 4 oxidation, the growth of methanotrophs, and the distribution of CH 4 -derived carbon, which were related to the ratio of the toluene concentration to biomass. These results would be helpful to understand the metabolism of CH 4 and non-methane volatile organic compounds in the environment.

  8. Isolation and characterization of a novel toluene-degrading, sulfate-reducing bacterium.

    Science.gov (United States)

    Beller, H R; Spormann, A M; Sharma, P K; Cole, J R; Reinhard, M

    1996-01-01

    A novel sulfate-reducing bacterium isolated from fuel-contaminated subsurface soil, strain PRTOL1, mineralizes toluene as the sole electron donor and carbon source under strictly anaerobic conditions. The mineralization of 80% of toluene carbon to CO2 was demonstrated in experiments with [ring-U-14C]toluene; 15% of toluene carbon was converted to biomass and nonvolatile metabolic by-products, primarily the former. The observed stoichiometric ratio of moles of sulfate consumed per mole of toluene consumed was consistent with the theoretical ratio for mineralization of toluene coupled with the reduction of sulfate to hydrogen sulfide. Strain PRTOL1 also transforms o- and p-xylene to metabolic products when grown with toluene. However, xylene transformation by PRTOL1 is slow relative to toluene degradation and cannot be sustained over time. Stable isotope-labeled substrates were used in conjunction with gas chromatography-mass spectrometry to investigate the by-products of toluene and xylene metabolism. The predominant by-products from toluene, o-xylene, and p-xylene were benzylsuccinic acid, (2-methylbenzyl)succinic acid, and 4-methylbenzoic acid (or p-toluic acid), respectively. Metabolic by-products accounted for nearly all of the o-xylene consumed. Enzyme assays indicated that acetyl coenzyme A oxidation proceeded via the carbon monoxide dehydrogenase pathway. Compared with the only other reported toluene-degrading, sulfate-reducing bacterium, strain PRTOL1 is distinct in that it has a novel 16S rRNA gene sequence and was derived from a freshwater rather than marine environment. PMID:8919780

  9. Recognizing Symptoms

    Science.gov (United States)

    ... for IBS Signs and Symptoms Overview Recognizing Symptoms Diagnosis of IBS Pain in IBS IBS with Constipation Constipated Diarrhea IBS ... for IBS Signs and Symptoms Overview Recognizing Symptoms Diagnosis of IBS Pain in IBS IBS with Constipation Constipated Diarrhea IBS ...

  10. Acute symptoms during non-inhalation exposure to combinations of toluene, trichloroethylene, and n-hexane

    DEFF Research Database (Denmark)

    Bælum, Jesper

    1999-01-01

    To study the acute effect of exposure to a mixture of three commonly used solvents in humans using a route of exposure not involving the nose and lungs, in this case a gastrointestinal application....

  11. Metabolic interaction between toluene, trichloroethylene and n-hexane in humans

    DEFF Research Database (Denmark)

    Bælum, Jesper; Mølhave, Lars; Hansen, Steen Honoré

    1998-01-01

    OBJECTIVES: This human experimental study describes the mutual metabolic interaction between toluene, trichloroethylene, and n-hexane. METHODS: Eight healthy male volunteers were exposed to combinations of toluene (1.5 or 4 mg/min), trichloroethylene (1.5 or 4 mg/min), and n-hexane (0.3 or 1.0 mg...

  12. Selective alkylation of toluene over basic zeolites: an in situ infrared spectroscopic investigation

    NARCIS (Netherlands)

    Palomares gimeno, A.E.; Palomares, A.E.; Eder-Mirth, G.; Mirth, G.C.; Lercher, J.A.

    1997-01-01

    In situinfrared spectroscopy was used to study the sorption and reaction of toluene and methanol over various alkali exchanged X zeolites. The size of the metal cations controls the preference of sorbing methanol or toluene. The smaller the cation, the higher the preference for methanol is. A

  13. alkylation of toluene over basic catalysts - key requirements for side chain alkylation

    NARCIS (Netherlands)

    Palomares gimeno, A.E.; Palomares, A.E.; Eder-Mirth, G.; Mirth, G.C.; Rep, M.; Rep, M.; Lercher, J.A.

    1998-01-01

    In situinfrared spectroscopy was used to study sorption and reaction of toluene and methanol over various basic catalysts (MgO, hydrotalcites, and basic zeolites). The size of the metal cations controls the preference of sorbing methanol or toluene; i.e., the larger the metal cation, the higher the

  14. Use of Selective Inhibitors and Chromogenic Substrates to Differentiate Bacteria Based on Toluene Oxygenase Activity

    Energy Technology Data Exchange (ETDEWEB)

    Keener, William Kelvin; Schaller, Kastli Dianne; Walton, Michelle Rene; Partin, Judy Kaye; Watwood, Mary Elizabeth; Smith, William Aaron; Chingenpeel, S. R.

    2001-09-01

    In whole-cell studies, two alkynes, 1-pentyne and phenylacetylene, were selective, irreversible inhibitors of monooxygenase enzymes in catabolic pathways that permit growth of bacteria on toluene. 1-Pentyne selectively inhibited growth of Burkholderia cepacia G4 (toluene 2-monooxygenase [T2MO] pathway) and B. pickettii PKO1 (toluene 3-monooxygenase [T3MO] pathway) on toluene, but did not inhibit growth of bacteria expressing other pathways. In further studies with strain G4, chromogenic transformation of a,a,a-Trifluoro-m-cresol (TFC) was irreversibly inhibited by 1-pentyne, but the presence of phenol prevented this inhibition. Transformation of catechol by G4 was unaffected by 1-pentyne. With respect to the various pathways and bacteria tested, phenylacetylene selectively inhibited growth of Pseudomonas mendocina KR1 (toluene 4-monooxygenase [T4MO] pathway) on toluene, but not on p-cresol. An Escherichia coli transformant expressing T4MO transformed indole or naphthalene in chromogenic reactions, but not after exposure to phenylacetylene. The naphthalene reaction remained diminished in phenylacetylene-treated cells relative to untreated cells after phenylacetylene was removed, indicating irreversible inhibition. These techniques were used to differentiate toluene-degrading isolates from an aquifer. Based on data generated with these indicators and inhibitors, along with results from Biolog analysis for sole carbon source oxidation, the groundwater isolates were assigned to eight separate groups, some of which apparently differ in their mode of toluene catabolism.

  15. Toluene biodegradation and biofilm growth in an aerobic fixed-film reactor

    DEFF Research Database (Denmark)

    Arcangeli, Jean-Pierre; Arvin, Erik

    1992-01-01

    Aerobic biodegradation of toluene in a biofilm system was investigated. Toluene is easily biodegradable, like several other aromatic compounds. The degradation was first order at bulk concentrations lower than 0.14 mg/l and zero order above 6–8 mg/l. An average yield coefficient of 1 mg biomass/m...

  16. Toluene-induced, Ca2+-dependent vesicular catecholamine release in rat PC12 cells

    NARCIS (Netherlands)

    Westerink, R.H.S.; Vijverberg, H.P.M.

    2002-01-01

    Acute effects of toluene on vesicular catecholamine release from intact PC12 phaeochromocytoma cells have been investigated using carbon fiber microelectrode amperometry. The frequency of vesicles released is low under basal conditions and is enhanced by depolarization. Toluene causes an increase in

  17. Effect of trichloroethylene on the competitive behavior of toluene-degrading bacteria

    NARCIS (Netherlands)

    Mars, Astrid E.; Prins, Gjalt T.; Wietzes, Pieter; Koning, Wim de; Janssen, Dick B.

    The influence of trichloroethylene (TCE) on a mixed culture of four different toluene-degrading bacterial strains (Pseudomonas putida mt-2, P. putida F1, P. putida GJ31, and Burkholderia cepacia G4) was studied with a fed-batch culture. The strains were competing for toluene, which was added at a

  18. Health risk assessment and applied action level of toluene. Final report

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-05-16

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

  19. Detection of Toluene Degradation in Bacteria Isolated from Oil Contaminated Soils

    International Nuclear Information System (INIS)

    Ainon Hamzah; Tavakoli, A.; Amir Rabu

    2011-01-01

    Toluene (C 7 H 8 ) a hydrocarbon in crude oil, is a common contaminant in soil and groundwater. In this study, the ability to degrade toluene was investigated from twelve bacteria isolates which were isolated from soil contaminated with oil. Out of 12 bacterial isolates tested, most of Pseudomonas sp. showed the capability to grow in 1 mM of toluene compared with other isolates on the third day of incubation. Based on enzyme assays towards toluene monooxygenase, Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were shown to have the highest ability to degrade toluene. The toluene monooxygenase activity was analysed by using two calorimetric methods, Horseradish peroxidase (HRP) and indole-indigo. Both of the methods measured the production of catechol by the enzymatic reaction of toluene monooxygenase. In the HRP assay, the highest enzyme activity was 0.274 U/ mL, exhibited by Pseudomonas aeruginosa UKMP-14T. However, for indole-indigo assay, Bacillus cereus UKMP-6G produced the highest enzyme activity of 0.291 U/ ml. Results from both experiments showed that Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were able to degrade toluene. (author)

  20. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE, IN VIVO

    Science.gov (United States)

    In vitro, toluene disrupts the function of NMDA-glutamate receptors, indicating that effects on NMDA receptor function may contribute to toluene neurotoxicity. NMDA-glutamate receptors are widely present in the visual system and contribute to pattern-elicited visual evoked potent...

  1. Differential cardiac effects in rats exposed to atmospheric smog generated from isoprene versus toluene

    Science.gov (United States)

    The results of this study demonstrate that atmospheric smog generated from both isoprene and toluene cause cardiac effects in rats. In addition, it appears that smog from toluene is more toxic in terms of cardiac arrhythmogenicity. Smog, which is a comple...

  2. Impact of a new condensed toluene mechanism on air quality model predictions in the US

    Directory of Open Access Journals (Sweden)

    G. Sarwar

    2011-03-01

    Full Text Available A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0–3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone concentrations. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. A sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While it increases in-cloud secondary organic aerosol substantially, its impact on total fine particle mass concentration is small.

  3. Toluene impurity effects on CO2 separation using a hollow fiber membrane for natural gas

    KAUST Repository

    Omole, Imona C.

    2011-03-01

    The performance of defect-free cross-linkable polyimide asymmetric hollow fiber membranes was characterized using an aggressive feed stream containing up to 1000ppm toluene. The membrane was shown to be stable against toluene-induced plasticization compared with analogs made from Matrimid®, a commercial polyimide. Permeation and sorption analysis suggest that the introduction of toluene vapors in the feed subjects the membrane to antiplasticization, as the permeance decreases significantly (to less than 30%) under the most aggressive conditions tested. Separation efficiencies reflected by permselectivities were less affected. The effect of the toluene on the membrane was shown to be reversible when the toluene was removed. © 2010 Elsevier B.V.

  4. Viscometric study of high-cis polybutadiene in toluene solution

    Directory of Open Access Journals (Sweden)

    Mello Ivana L.

    2006-01-01

    Full Text Available Viscometric measurements, in toluene solution at 30 ºC, were performed with high-cis polybutadiene synthesized by neodymium based catalyst. Six different equations were used to calculate intrinsic viscosities and viscosimetric constant values: Huggins, Kraemer, Martin and Schulz-Blaschke by graphic extrapolation, and Solomon-Ciuta, Deb-Chanterjee and again Schulz-Blaschke, through a single point determination. The molecular weight of the polymers was also determined applying Mark-Houwink-Sakurada equation using the values of intrinsic viscosity obtained by the six equations. The values of intrinsic viscosity and viscosity-average molecular weight obtained by the two methods were compared in order to verify the validity of the single point determination for high-cis polybutadiene.

  5. Global transcriptional response of solvent-sensitive and solvent-tolerant Pseudomonas putida strains exposed to toluene

    DEFF Research Database (Denmark)

    Molina-Santiago, Carlos; Udaondo, Zulema; Gómez Lozano, María

    2017-01-01

    to reduce toluene membrane permeability. The KT2440 strain activates the TCA cycle to generate energy, while avoiding energy-intensive processes such as flagellar biosynthesis. This suggests that KT2440 responds to toluene by focusing on survival mechanisms. The DOT-T1E strain activates toluene degradation...

  6. Degradation of toluene and trichloroethylene by Burkholderia cepacia G4 in growth-limited fed-batch culture

    NARCIS (Netherlands)

    Mars, Astrid E.; Houwing, Joukje; Dolfing, Jan; Janssen, Dick B.

    Burkholderia (Pseudomonas) cepacia G4 was cultivated in a fed-batch bioreactor on either toluene or toluene plus trichloroethylene (TCE), The culture was allowed to reach a constant cell density under conditions in which the amount of toluene supplied equals the maintenance energy demand of the

  7. Amyotrophic lateral sclerosis-A case report and mechanistic review of the association with toluene and other volatile organic compounds.

    Science.gov (United States)

    Ratner, Marcia H; Jabre, Joe F; Ewing, William M; Abou-Donia, Mohamed; Oliver, L Christine

    2018-03-01

    Unmasking of latent neurodegenerative disease has been reported following exposure to chemicals that share one or more mechanisms of action in common with those implicated in the specific disease. For example, unmasking of latent Parkinson's disease (PD) has been associated with exposure to anti-dopaminergic agents, while the progression of pre-existing mild cognitive impairment and unmasking of latent Alzheimer's disease has been associated with exposure to general anesthetic agents which promote Aβ protein aggregation. This literature review and clinical case report about a 45-year-old man with no family history of motor neuron disease who developed overt symptoms of a neuromuscular disorder in close temporal association with his unwitting occupational exposure to volatile organic compounds (VOCs) puts forth the hypothesis that exposure to VOCs such as toluene, which disrupt motor function and increase oxidative stress, can unmask latent ALS type neuromuscular disorder in susceptible individuals. © 2017 Wiley Periodicals, Inc.

  8. Liver function in patients exposed to a toluene in a hydrocarbon processing plant

    International Nuclear Information System (INIS)

    Sanchez, E; Fernandez D'Pool, J.

    1996-01-01

    Since the hepatotoxic role of toluene in exposed workers from the petroleum and petrochemical industries chronically exposed to low concentration has no been entirely dilucidated, this transversal study was undertaken in order to clarify the situation in the local industries. A group of 33 non-exposed men workers of such industries (group control, aged 33.0 +/- 4.88 years) were compared with 33 toluene-exposed men (aged 35.0 +/- 9.33 years) from the related industries, with a minimal of 6 months exposition time to toluene and without liver disease history. In addition to a complete occupational diseases medical history, each subject was tested by both a venous blood sample (to determine prothrombin, total and fractioned bilirubin, total and fractioned proteins, liver enzymes and cholesterol) and urine sample (hippuric acid). Also the environmental concentration of toluene in working areas was determined by gas chromatography, which was below the recommended standard levels in working areas. Although the analyzed parameters were in the normal range, it was observed that those workers with known alcohol ingestion and toluene exposition had several abnormalities. The results of this study confirm that toluene may have a synergistic hepatotoxic effect in toluene-exposed workers that are alcohol consumers. The alcohol in considered as a confounding factor and it is not possible to rule out in the etiology of hepatic changes detected in the study

  9. Microbial characterization of toluene-degrading denitrifying consortia obtained from terrestrial and marine ecosystems.

    Science.gov (United States)

    An, Y-J; Joo, Y-H; Hong, I-Y; Ryu, H-W; Cho, K-S

    2004-10-01

    The degradation characteristics of toluene coupled to nitrate reduction were investigated in enrichment culture and the microbial communities of toluene-degrading denitrifying consortia were characterized by denaturing gradient gel electrophoresis (DGGE) technique. Anaerobic nitrate-reducing bacteria were enriched from oil-contaminated soil samples collected from terrestrial (rice field) and marine (tidal flat) ecosystems. Enriched consortia degraded toluene in the presence of nitrate as a terminal electron acceptor. The degradation rate of toluene was affected by the initial substrate concentration and co-existence of other hydrocarbons. The types of toluene-degrading denitrifying consortia depended on the type of ecosystem. The clone RS-7 obtained from the enriched consortium of the rice field was most closely related to a toluene-degrading and denitrifying bacterium, Azoarcus denitrificians (A. tolulyticus sp. nov.). The clone TS-11 detected in the tidal flat enriched consortium was affiliated to Thauera sp. strain S2 (T. aminoaromatica sp. nov.) that was able to degrade toluene under denitrifying conditions. This indicates that environmental factors greatly influence microbial communities obtained from terrestrial (rice field) and marine (tidal flat) ecosystems.

  10. Analysis of residual toluene in food packaging via headspace extraction method using gas chromatography

    International Nuclear Information System (INIS)

    Lim, Ying Chin; Mohd Marsin Sanagi

    2008-01-01

    Polymeric materials are used in many food contact applications as packaging material. The presence of residual toluene in this food packaging material can migrate into food and thus affect the quality of food. In this study, a manual headspace analysis was successfully designed and developed. The determination of residual toluene was carried out with standard addition method and multiple headspace extraction, MHE) method using gas chromatography-flame ionization detector, GC-FID). Identification of toluene was performed by comparison of its retention time with standard toluene and GC-MS. It was found that the suitable heating temperature was 180 degree Celsius with an optimum heating time of 10 minutes. The study also found that the concentration of residual toluene in multicolored sample was higher compared to mono colored sample whereas residual toluene in sample analyzed using standard addition method was higher compared to MHE method. However, comparison with the results obtained from De Paris laboratory, France found that MHE method gave higher accuracy for sample with low analyte concentration. On the other hand, lower accuracy was obtained for sample with high concentration of residual toluene due to systematic errors. Comparison between determination methods showed that MHE method is more precise compared to standard addition method. (author)

  11. Biodegradation of toluene vapor in coir based upflow packed bed reactor by Trichoderma asperellum isolate.

    Science.gov (United States)

    Gopinath, M; Mohanapriya, C; Sivakumar, K; Baskar, G; Muthukumaran, C; Dhanasekar, R

    2016-03-01

    In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m(-3) h(-1)) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.

  12. Degradation of chloroanilines by toluene dioxygenase from Pseudomonas putida T57.

    Science.gov (United States)

    Nitisakulkan, Tisana; Oku, Shota; Kudo, Daizo; Nakashimada, Yutaka; Tajima, Takahisa; Vangnai, Alisa S; Kato, Junichi

    2014-03-01

    In this study, we investigated the ability of Pseudomonas putida toluene dioxygenase to oxidize chloroanilines. Toluene-induced P. putida T57 cells degraded 4-chloroaniline (4CA) more rapidly than toluene-non-induced cells, suggesting that toluene dioxygenase pathway was involved in 4CA degradation. Escherichia coli harboring P. putida T57 genes encoding toluene dioxygenase complex (todC1C2BA) showed 4CA degradation activity, demonstrating that toluene dioxygenase oxidizes 4CA. Thin-layer chromatography (TLC) and mass spectrometry (MS) analyses identified 4-chlorocatechol and 2-amino-5-chlorophenol as reaction products, suggesting that toluene dioxygenase catalyzes both 1,2- and 2,3-dioxygenation of 4CA. A plasmid containing the entire tod operon (todC1C2BADE) was introduced to P. putida T57 to enhance its ability to degrade 4CA. Resulting P. putida T57 (pHK-C1C2BADE) showed 250-fold higher 4CA degradation activity than P. putida T57 parental strain. P. putida T57 (pHK-C1C2BADE) degraded 2-chloroaniline (2CA), 3-chloroaniline (3CA), and 3,4-dichloroaniline (34DCA) as well as 4CA, but not 3,5-dichloroaniline (35DCA). The order of the degradation rate was: 4CA > 3CA > 2CA > 34DCA. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  13. Sarcosine attenuates toluene-induced motor incoordination, memory impairment, and hypothermia but not brain stimulation reward enhancement in mice

    International Nuclear Information System (INIS)

    Chan, Ming-Huan; Chung, Shiang-Sheng; Stoker, Astrid K.; Markou, Athina; Chen, Hwei-Hsien

    2012-01-01

    Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances, including motor incoordination and cognitive impairment. Toluene alters the function of a large number of receptors and ion channels. Blockade of N-methyl-D-aspartate (NMDA) receptors has been suggested to play a critical role in toluene-induced behavioral manifestations. The present study determined the effects of various toluene doses on motor coordination, recognition memory, body temperature, and intracranial self-stimulation (ICSS) thresholds in mice. Additionally, the effects of sarcosine on the behavioral and physiological effects induced by toluene were evaluated. Sarcosine may reverse toluene-induced behavioral manifestations by acting as an NMDA receptor co-agonist and by inhibiting the effects of the type I glycine transporter (GlyT1). Mice were treated with toluene alone or combined with sarcosine pretreatment and assessed for rotarod performance, object recognition memory, rectal temperature, and ICSS thresholds. Toluene dose-dependently induced motor incoordination, recognition memory impairment, and hypothermia and lowered ICSS thresholds. Sarcosine pretreatment reversed toluene-induced changes in rotarod performance, novel object recognition, and rectal temperature but not ICSS thresholds. These findings suggest that the sarcosine-induced potentiation of NMDA receptors may reverse motor incoordination, memory impairment, and hypothermia but not the enhancement of brain stimulation reward function associated with toluene exposure. Sarcosine may be a promising compound to prevent acute toluene intoxications by occupational or intentional exposure. -- Highlights: ► Toluene induces impairments in Rotarod test and novel object recognition test. ► Toluene lowers rectal temperature and ICSS thresholds in mice. ► Sarcosine reverses toluene-induced changes in motor, memory and body temperature. ► Sarcosine pretreatment does not affect toluene

  14. Sarcosine attenuates toluene-induced motor incoordination, memory impairment, and hypothermia but not brain stimulation reward enhancement in mice

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Ming-Huan [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Institute of Neuroscience, National Changchi University, Taipei, Taiwan (China); Chung, Shiang-Sheng [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Department of Pharmacy, Yuli Veterans Hospital, Hualien, Taiwan (China); Stoker, Astrid K.; Markou, Athina [Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA (United States); Chen, Hwei-Hsien, E-mail: hwei@nhri.org.tw [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Division of Mental Health and Addiction Medicine, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China)

    2012-12-01

    Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances, including motor incoordination and cognitive impairment. Toluene alters the function of a large number of receptors and ion channels. Blockade of N-methyl-D-aspartate (NMDA) receptors has been suggested to play a critical role in toluene-induced behavioral manifestations. The present study determined the effects of various toluene doses on motor coordination, recognition memory, body temperature, and intracranial self-stimulation (ICSS) thresholds in mice. Additionally, the effects of sarcosine on the behavioral and physiological effects induced by toluene were evaluated. Sarcosine may reverse toluene-induced behavioral manifestations by acting as an NMDA receptor co-agonist and by inhibiting the effects of the type I glycine transporter (GlyT1). Mice were treated with toluene alone or combined with sarcosine pretreatment and assessed for rotarod performance, object recognition memory, rectal temperature, and ICSS thresholds. Toluene dose-dependently induced motor incoordination, recognition memory impairment, and hypothermia and lowered ICSS thresholds. Sarcosine pretreatment reversed toluene-induced changes in rotarod performance, novel object recognition, and rectal temperature but not ICSS thresholds. These findings suggest that the sarcosine-induced potentiation of NMDA receptors may reverse motor incoordination, memory impairment, and hypothermia but not the enhancement of brain stimulation reward function associated with toluene exposure. Sarcosine may be a promising compound to prevent acute toluene intoxications by occupational or intentional exposure. -- Highlights: ► Toluene induces impairments in Rotarod test and novel object recognition test. ► Toluene lowers rectal temperature and ICSS thresholds in mice. ► Sarcosine reverses toluene-induced changes in motor, memory and body temperature. ► Sarcosine pretreatment does not affect toluene

  15. Plague Symptoms

    Science.gov (United States)

    ... Healthcare Professionals Clinicians Public Health Officials Veterinarians Prevention History of Plague Resources FAQ Symptoms Recommend on Facebook Tweet Share Compartir Plague symptoms depend on how ...

  16. Side-chain alkylation of toluene with methanol over Zn-modified KX zeolite

    OpenAIRE

    Song, Lanlan; Yu, Yue; Li, Zhenrong; Guo, Shaoqing; Zhao, Liangfu; Li, Wen

    2014-01-01

    The effect of Zn on side-chain alkylation of toluene with methanol over KX zeolite was investigated. It was found that the addition of Zn with a low content over KX could enhance toluene conversion significantly. In addition, the results showed that the conversion of toluene over ZnKX (0.8 wt. %) catalyst was almost twice as high as that over KX. The catalysts were characterized by X-ray diffraction (XRD), N2 physisorption, NH3-temperature-programmed desorption (TPD), pyridine absorption infr...

  17. Diazepam influences urinary bioindicator of occupational toluene exposure.

    Science.gov (United States)

    Silveira, Alberto Thalison; Albuquerque, Ana Carolina Campos; Lepera, José Salvador; Martins, Isarita

    2016-12-01

    In the present study, we investigated the influence of diazepam (DZP) on the excretion of TOL by examining their urinary metabolites, hippuric acid (HA) and ortho-cresol (o-C). Male Wistar rats were exposed to TOL (20ppm) in a nose-only exposure chamber (6h/day, 5days/week for 6 weeks) with simultaneous administration of DZP (10mg/kg/day). Urinary o-C levels were determined by GC-MS, while HA, creatinine (CR), DZP and its metabolite, nordiazepam, were analysed by HPLC-DAD. The results of a Mann-Whitney U test showed that DZP influenced the urinary excretion of o-C (p<0.05). This pioneering study revealed that there was an interaction between DZP and TOL, probably by the inhibition of the CYP isoforms (CYP2B6, CYP2C8, CYP2E1, and CYP1A2) involved in the oxidative metabolism of the solvent. This is relevant information to be considered in the biomonitoring of occupational toluene exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

    Science.gov (United States)

    Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

    2017-07-01

    Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

  19. Toluene pyrolysis studies and high temperature reactions of propargyl chloride

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

    The main focus of this program is to investigate the thermal decompositions of fuels that play an important role in the pre-particle soot formation process. It has been demonstrated that the condition of maximum soot yield is established when the reaction conditions of temperature and pressure are sufficient to establish a radical pool to support the production of polyaromatic hydrocarbon species and the subsequent formation of soot particles. However, elevated temperatures result in lower soot yields which are attributed to thermolyses of aromatic ring structures and result in the bell-shaped dependence of soot yield on temperature. The authors have selected several acyclic hydrocarbons to evaluate the chemical thermodynamic and kinetic effects attendant to benzene formation. To assess the thermal stability of the aromatic ring, the authors have studied the pyrolyses of benzene, toluene, ethylbenzene, chlorobenzene and pyridine. Time-of-flight mass spectrometry (TOF) is employed to analyze the reaction zone behind reflected shock waves. Reaction time histories of the reactants, products, and intermediates are constructed and mechanisms are formulated to model the experimental data. The TOF work is often performed with use of laser schlieren densitometry (LS) to measure density gradients resulting from the heats of various reactions involved in a particular pyrolytic system. The two techniques, TOF and LS, provide independent and complementary information about ring formation and ring rupture reactions.

  20. Thermal desorption of toluene from Vanadium-containing catalysts coated onto various carriers

    Directory of Open Access Journals (Sweden)

    Z. Zheksenbaeva

    2012-12-01

    Full Text Available The method temperature-programmed desorption has been studied the state of toluene on the surface-modified vanadium catalysts on different carriers. Among the investigated carriers the most active in the reaction of partial oxidation of toluene is anatase structural titanium dioxide. For the partial oxidation of toluene on modified vanadium-containing catalysts deposited on TiO2 was tested. It was found that on the catalyst 20%V2O5-5%MoO3-2%Sb2O3/TiO2 at a temperature of 673K, volume rate of 15 thousand hours-1 oxidation of toluene is 80% c yield of benzoic acid with a selectivity of  70% of 87.5%.

  1. Breakthrough of toluene vapours in granular activated carbon filled packed bed reactor

    International Nuclear Information System (INIS)

    Mohan, N.; Kannan, G.K.; Upendra, S.; Subha, R.; Kumar, N.S.

    2009-01-01

    The objective of this research was to determine the toluene removal efficiency and breakthrough time using commercially available coconut shell-based granular activated carbon in packed bed reactor. To study the effect of toluene removal and break point time of the granular activated carbon (GAC), the parameters studied were bed lengths (2, 3, and 4 cm), concentrations (5, 10, and 15 mg l -1 ) and flow rates (20, 40, and 60 ml/min). The maximum percentage removal of 90% was achieved and the maximum carbon capacity for 5 mg l -1 of toluene, 60 ml/min flow rate and 3 cm bed length shows 607.14 mg/g. The results of dynamic adsorption in a packed bed were consistent with those of equilibrium adsorption by gravimetric method. The breakthrough time and quantity shows that GAC with appropriate surface area can be utilized for air cleaning filters. The result shows that the physisorption plays main role in toluene removal.

  2. TOXICITY OF AROMATIC AEROBIC BIOTRANSFORMATION PRODUCTS OF TOLUENE TO HELA CELLS

    Science.gov (United States)

    Petroleum contamination of groundwater is widely recognized as a serious environmental problem. Toluene (methylbenzene) occurs naturally in crude oil and is commonly found as a contaminant in the subsurface as a result of waste disposal and storage activities. Biological transf...

  3. Hydrogenation of toluene on Ni-Co-Mo supported zeolite catalysts ...

    African Journals Online (AJOL)

    -a, HY-b and Mordenite were prepared and characterized using many techniques for use as hydrotreating catalysts. In a preliminary investigation, toluene was employed as model compound to test the catalysts in hydrogenation, as a major ...

  4. Psychological autopsy and necropsy of an unusual case of suicide by intravenous toluene

    OpenAIRE

    Ranganath R Kulkarni; R G Hemanth Kumar; Pratibha R Kulkarni; Raghavendra B Kotabagi

    2015-01-01

    Toluene (methylbenzene; volatile hydrocarbon) is an industrial solvent that causes major injury to the lungs; the organ being the first capillary bed encountered. We report an unusual case of suicide by a 24-year-old male, paramedical professional, with fatal outcome within 16 h of intentional, intravenous self-administration of toluene, with clinical presentation of acute respiratory distress syndrome. Psychological autopsy revealed severe depressive disorder and solvent (inhalant) abuse, wi...

  5. Blending Octane Number of Toluene with Gasoline-like and PRF Fuels in HCCI Combustion Mode

    KAUST Repository

    Waqas, Muhammad Umer

    2018-04-03

    Future internal combustion engines demand higher efficiency but progression towards this is limited by the phenomenon called knock. A possible solution for reaching high efficiency is Octane-on-Demand (OoD), which allows to customize the antiknock quality of a fuel through blending of high-octane fuel with a low octane fuel. Previous studies on Octane-on-Demand highlighted efficiency benefits depending on the combination of low octane fuel with high octane booster. The author recently published works with ethanol and methanol as high-octane fuels. The results of this work showed that the composition and octane number of the low octane fuel is significant for the blending octane number of both ethanol and methanol. This work focuses on toluene as the high octane fuel (RON 120). Aromatics offers anti-knock quality and with high octane number than alcohols, this work will address if toluene can provide higher octane enhancement. Our aim is to investigate the impact of three gasoline-like fuels and two Primary Reference Fuels (PRFs). More specifically, fuels are FACE (Fuels for Advanced Combustion Engines) I, FACE J, FACE A, PRF 70 and PRF 84. A CFR engine was used to conduct the experiments in HCCI mode. For this combustion mode, the engine operated at four specific conditions based on RON and MON conditions. The octane numbers corresponding to four HCCI numbers were obtained for toluene concentration of 0, 2, 5, 10, 15 and 20%. Results show that the blending octane number of toluene varies non-linearly and linearly with the increase in toluene concentration depending on the base fuel, experimental conditions and the concentration of toluene. As a result, the blending octane number can range from close to 150 with a small fraction of toluene to a number closer to that of toluene, 120, with larger fractions.

  6. Highly regioselective dinitration of toluene over reusable zeolite H-beta

    OpenAIRE

    Smith, Keith; Alotaibi, Mohammad Hayal H.; El-Hiti, Gamal A.

    2013-01-01

    A nitration system comprising nitric acid, propanoic anhydride and zeolite H-beta has been developed for dinitration of toluene to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of over 120. This represents the most selective quantitative method for 2,4-dinitration of toluene; the catalyst is re-usable, solvent is not needed and an aqueous work-up is not required.

  7. Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

    KAUST Repository

    Sinha, Sourab

    2014-10-22

    The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

  8. Uptake of toluene and ethylbenzene by plants: removal of volatile indoor air contaminants.

    Science.gov (United States)

    Sriprapat, Wararat; Suksabye, Parinda; Areephak, Sirintip; Klantup, Polawat; Waraha, Atcharaphan; Sawattan, Anuchit; Thiravetyan, Paitip

    2014-04-01

    Air borne uptake of toluene and ethylbenzene by twelve plant species was examined. Of the twelve plant species examined, the highest toluene removal was found in Sansevieria trifasciata, while the ethylbenzene removal from air was with Chlorophytum comosum. Toluene and ethylbenzene can penetrate the plant׳s cuticle. However, the removal rates do not appear to be correlated with numbers of stomata per plant. It was found that wax of S. trifasciata and Sansevieria hyacinthoides had greater absorption of toluene and ethylbenzene, and it contained high hexadecanoic acid. Hexadecanoic acid might be involved in toluene and ethylbenzene adsorption by cuticles wax of plants. Chlorophyll fluorescence analysis or the potential quantum yield of PSII (Fv/Fm) in toluene exposed plants showed no significant differences between the control and the treated plants, whereas plants exposed to ethylbenzene showed significant differences or those parameters, specifically in Dracaena deremensis (Lemon lime), Dracaena sanderiana, Kalanchoe blossfeldiana, and Cordyline fruticosa. The Fv/Fm ratio can give insight into the ability of plants to tolerate (indoor) air pollution by volatile organic chemicals (VOC). This index can be used for identification of suitable plants for treating/sequestering VOCs in contaminated air. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Effects of toluene on protein synthesis and the interaction with ethanol in hepatocytes isolated from fed and fasted rats

    International Nuclear Information System (INIS)

    Smith-Kielland, A.; Ripel, Aa.; Gadeholt, G.

    1989-01-01

    The effects of three different concentrations (about 20, 100 and 1000 μM) of toluene on protein synthesis were studied in hepatocytes isolated from fed and fasted rats after 60 and 120 min. of incubation. The interaction between ethanol (60 mM) and the low and high toluene concentrations were also tested. To measure protein synthesis, 14 C-valine was used as the precursor amino acid. Total valine concentration was 2 mM to ensure near-constant specific radioactivity of precursor. Toluene concentrations were measured by head-space gas chromatography. Protein synthesis was unchanged in the presence of low toluene concentrations. Intermediate toluene concentration decreased protein synthesis by about 20% and high toluene concentration decreased protein synthesis by about 60%. Protein synthesis was similar in cells from fed and fasted rats. Ethanol alone inhibited protein synthesis by 20-30%, more in fasted than in fed rats. Toluene and ethanol in combination inhibited protein synthesis additively. The high toluene concentration with or without ethanol appeared to inhibit synthesis/secretion of export proteins in hepatocytes from fasted rats. In conclusion, our study indicates that toluene in relatively high concentrations inhibits general protein synthesis in isolated rat hepatocytes. Toluene and ethanol seems to inhibit protein synthesis additively. (author)

  10. The effects of toluene plus noise on hearing thresholds: an evaluation based on repeated measurements in the German printing industry.

    Science.gov (United States)

    Schäper, Michael; Seeber, Andreas; van Thriel, Christoph

    2008-01-01

    The ototoxicity of occupational exposure to toluene plus noise was investigated in a longitudinal study in rotogravure printing and existing findings in the literature were evaluated. The study comprised four repeated examinations during 5 years and started with 333 male workers. Lifetime weighted average exposures (LWAE) to toluene and noise were determined from individual work histories and historic recordings; recent individual exposures were measured 10 times during the study (toluene, active sampling; noise, stationary measurements). Auditory thresholds were measured with pure tone audiometry at 0.125, 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 12 kHz. Mean LWAE exposures to toluene and noise were 45+/-17 ppm plus 82+/-7 dB(A) for high toluene exposed and 10+/-7 ppm plus 82+/-4 dB(A) for low toluene exposed subjects, mean current exposures were 26+/-20 ppm plus 81+/-4 dB(A) and 3+/-3 ppm plus 82+/-4 dB(A). Mean exposure duration was 21.3+/-6.5 years for long exposed and 5.9+/-2.2 years for short exposed subjects. Repeated measurement analyses of variance did not reveal effects of toluene intensity, exposure duration and interactions between toluene intensity and noise intensity. Noise intensity [79+/-3 dB(A) vs. 84+/-1 dB(A)] was significant for auditory thresholds. A case concept utilising developments of individual auditory thresholds did not reveal significant toluene effects. Logistic models including age, exposure duration, toluene in ambient air, current noise and either hippuric acid or ortho-cresol (o-cresol) found only age to be significant for elevated OR of high frequency hearing loss. Due to missing toluene effects, it was concluded that the threshold level for developing hearing loss as a result of occupational exposure to toluene plus noise might be above the current limit of 50 ppm toluene.

  11. Effects of Isoprene- and Toluene-Generated Smog on Allergic ...

    Science.gov (United States)

    Reactions of organic compounds with nitric oxide (NO) and sunlight produce complex mixtures of pollutants including secondary organic aerosol (SOA), ozone (O3), nitrogen dioxide (NO2), and reactive aldehydes. The health effects of these photochemical smog mixtures in susceptible populations including asthmatics are unclear. We assessed effects of smog generated from mixtures of NO with isoprene (IS) or toluene (TL) on allergic inflammatory responses in Balb/cJ mice. House dust mite (HDM)-sensitized or control mice were all challenged with HDM intranasally 1 d prior to whole-body inhalation exposure to IS (chamber average 509 ppb NO2, 246 ppb O3, and 160 g/m3 SOA), TL (217 ppb NO2, 129 ppb O3, and 376 g/m3 SOA), or HEPA-filtered air (4 h/d for 2 days). Mice were necropsied within 3 h after the second exposure (2 d post-HDM challenge). Assessment of breathing parameters during exposure with double-chamber plethysmography showed a trend for increased specific airway resistance and decreased minute volume during the second day of TL exposure in both non-allergic and HDM-allergic mice. HDM-allergic air-exposed mice had significant increases in numbers of bronchoalveolar lavage (BAL) alveolar macrophages (AM) and eosinophils (EO), and trends for increases in BAL indices of lung injury in comparison with non-allergic air-exposed mice. Exposure to either IS or TL attenuated the increases in AM, EO, and lung injury markers in HDM-allergic mice. The results of this

  12. Exposure to the Abused Inhalant Toluene Alters Medial Prefrontal Cortex Physiology.

    Science.gov (United States)

    Wayman, Wesley N; Woodward, John J

    2018-03-01

    Inhalants, including toluene, target the addiction neurocircuitry and are often one of the first drugs of abuse tried by adolescents. The medial prefrontal cortex (mPFC) is involved in regulating goal-directed/reward-motivated behaviors and different mPFC sub-regions have been proposed to promote (prelimbic, PRL) or inhibit (infralimbic, IL) these behaviors. While this dichotomy has been studied in the context of other drugs of abuse, it is not known whether toluene exposure differentially affects neurons within PRL and IL regions. To address this question, we used whole-cell electrophysiology and determined the intrinsic excitability of PRL and IL pyramidal neurons in adolescent rats 24 h following a brief exposure to air or toluene vapor (10 500 p.p.m.). Prior to exposure, fluorescent retrobeads were injected into the NAc core (NAcc) or shell (NAcs) sub-regions to identify projection-specific mPFC neurons. In toluene treated adolescent rats, layer 5/6 NAcc projecting PRL (PRL5/6) neurons fired fewer action potentials and this was associated with increased rheobase, increased spike duration, and reductions in membrane resistance and amplitude of the I h current. No changes in excitability were observed in layer 2/3 NAcc projecting PRL (PRL2/3) neurons. In contrast to PRL neurons, layer 5 IL (IL5) and layer 2/3 (IL2/3) NAcc projecting neurons showed enhanced firing in toluene-exposed animals and in IL5 neurons, this was associated with a reduction in rheobase and AHP. For NAcs projecting neurons, toluene exposure significantly decreased firing of IL5 neurons and this was accompanied by an increased rheobase, increased spike duration, and reduced I h amplitude. The intrinsic excitability of PRL5, PRL2/3, and IL2/3 neurons projecting to the NAcs was not affected by exposure to toluene. The changes in excitability observed 24 h after toluene exposure were not observed when recordings were performed 7 days after the exposure. Finally, there were no changes in

  13. An SOA model for toluene oxidation in the presence of inorganic aerosols.

    Science.gov (United States)

    Cao, Gang; Jang, Myoseon

    2010-01-15

    A predictive model for secondary organic aerosol (SOA) formation including both partitioning and heterogeneous reactions is explored for the SOA produced from the oxidation of toluene in the presence of inorganic seed aerosols. The predictive SOA model comprises the explicit gas-phase chemistry of toluene, gas-particle partitioning, and heterogeneous chemistry. The resulting products from the explicit gas phase chemistry are lumped into several classes of chemical species based on their vapor pressure and reactivity for heterogeneous reactions. Both the gas-particle partitioning coefficient and the heterogeneous reaction rate constant of each lumped gas-phase product are theoretically determined using group contribution and molecular structure-reactivity. In the SOA model, the predictive SOA mass is decoupled into partitioning (OM(P)) and heterogeneous aerosol production (OM(H)). OM(P) is estimated from the SOA partitioning model developed by Schell et al. (J. Geophys. Res. 2001, 106, 28275-28293 ) that has been used in a regional air quality model (CMAQ 4.7). OM(H) is predicted from the heterogeneous SOA model developed by Jang et al. (Environ. Sci. Technol. 2006, 40, 3013-3022 ). The SOA model is evaluated using a number of the experimental SOA data that are generated in a 2 m(3) indoor Teflon film chamber under various experimental conditions (e.g., humidity, inorganic seed compositions, NO(x) concentrations). The SOA model reasonably predicts not only the gas-phase chemistry, such as the ozone formation, the conversion of NO to NO(2), and the toluene decay, but also the SOA production. The model predicted that the OM(H) fraction of the total toluene SOA mass increases as NO(x) concentrations decrease: 0.73-0.83 at low NO(x) levels and 0.17-0.47 at middle and high NO(x) levels for SOA experiments with high initial toluene concentrations. Our study also finds a significant increase in the OM(H) mass fraction in the SOA generated with low initial toluene

  14. Eye Symptoms

    Science.gov (United States)

    ... Prevention News Ask an Ophthalmologist Patient Stories Español Eye Symptoms This symptoms list is for general reference ... Y Z A-Z A B Blood in Eye Bloodshot Eye Blurriness Burning Eyes C Crusty Eyelid ...

  15. Activity of toluene-degrading Pseudomonas putida in the early growth phase of a biofilm for waste gas treatment

    DEFF Research Database (Denmark)

    Pedersen, A.R.; Møller, S.; Molin, S.

    1997-01-01

    the increase of active biomass and polymers was linear. In order to investigate the toluene degradation, various toluene degraders from the multispecies biofilm were isolated, and a Pseudomonas putida was chosen as a representative of the toluene-degrading population. A specific rRNA oligonucleotide probe...... was used to follow the toluene-degrading P. putida in the multispecies biofilm in the filter by means of number and cellular rRNA content. P. putida appeared to detach from the biofilm during the first three days of growth, after which P. putida was found at a constant level of 10% of the active biomass...... in the biofilm. Based on the rRNA content, the in situ activity was estimated to be reduced to 20% of cells grown at maximum conditions in batch culture. The toluene degraded by P. putida was estimated to be a minor part (11%) of the overall toluene degradation. (C) 1997 John Wiley & Sons, Inc....

  16. Changes in markers of oxidative stress and membrane properties in synaptosomes from rats exposed prenatally to toluene

    DEFF Research Database (Denmark)

    Edelfors, Sven; Hass, Ulla; Hougaard, Karin S.

    2002-01-01

    for the experiments, Synaptosomes from rats exposed prenatally to toluene exhibited an increased level of oxidative stress when incubated with toluene in vitro compared to synaptosomes from unexposed offspring. Also the cell membrane was affected, as the calcium leakage was more increased from exposed synaptosomes......The present study was undertaken in order to investigate if toluene induced oxidative stress in brains from rats exposed prenatally to 1800 ppm toluene 6 hr/day at days 7-20 during the pregnancy. 35-42 days after birth the rats were killed and synaptosomal fractions were prepared...... than from unexposed. The membrane fluidity increased significantly when synaptosomes were incubated with toluene for 10 min. in vitro but the change in fluidity was identical in both groups of offspring. The results indicate that prenatal exposure to toluene induces long-lasting changes in oxidative...

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

    OpenAIRE

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

    1991-01-01

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

  18. Chemogenetic Excitation of Accumbens-Projecting Infralimbic Cortical Neurons Blocks Toluene-Induced Conditioned Place Preference.

    Science.gov (United States)

    Wayman, Wesley N; Woodward, John J

    2018-02-07

    Abuse rates for inhalants among adolescents continue to be high, yet preclinical models for studying mechanisms underlying inhalant abuse remain limited. Our laboratory has previously shown that, in male rats, an acute binge-like exposure to toluene vapor that mimics human solvent abuse modifies the intrinsic excitability of mPFC pyramidal neurons projecting to the NAc. These changes showed region (infralimbic; IL vs prelimbic; PRL), layer (shallow; 2/3 vs deep; 5/6), target (core vs shell), and age (adolescent vs adult) dependent differences (Wayman and Woodward, 2017). To expand these findings using reward-based models that may better mimic human drug abuse, we used whole-cell electrophysiology and drug receptors exclusively activated by designer drugs to examine changes in neuronal function and behavior in rats showing a conditioned place preference (CPP) to toluene. Repeated pairings of adolescent rats to binge concentrations of toluene vapor previously shown to enhance dopamine release in reward-sensitive areas of the brain produced CPP that persisted for 7 but not 30 d. Toluene-induced CPP was associated with increased excitability of IL5/6 mPFC neurons projecting to the core of the NAc and reduced excitability of those projecting to the NAc shell. No changes in PRL-NAc-projecting neurons were found in toluene-CPP rats. Chemogenetic reversal of the toluene-induced decrease in IL5/6-NAc shell neurons blocked the expression of toluene-induced CPP while manipulating IL5/6-NAc core neuron activity had no effect. These data reveal that alterations in selective mPFC-NAc pathways are required for expression of toluene-induced CPP. SIGNIFICANCE STATEMENT Disturbed physiology of pyramidal neurons projecting from the mPFC to the NAc has been shown to have different roles in drug-seeking behaviors for a number of drugs (e.g., methamphetamine, cocaine, ecstasy, alcohol, heroin). Here, we report that rats repeatedly exposed to the volatile organic solvent toluene, a

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

    OpenAIRE

    Chee-Sanford, J C; Frost, J W; Fries, M R; Zhou, J; Tiedje, J M

    1996-01-01

    A toluene-degrading denitrifier, Azoarcus tolulyticus Tol-4, was one of eight similar strains isolated from three petroleum-contaminated aquifer sediments. When the strain was grown anaerobically on toluene, 68% of the carbon from toluene was found as CO2 and 30% was found as biomass. Strain Tol-4 had a doubling time of 4.3 h, a Vmax of 50 micromol x min-1 x g of protein-1, and a cellular yield of 49.6 g x mol of toluene-1. Benzoate appeared to be an intermediate, since F-benzoates accumulate...

  20. Sorption kinetics of toluene in humin under two different levels of relative humidity.

    Science.gov (United States)

    Shih, Yang-hsin; Wu, Shian-chee

    2002-01-01

    To identify any resistant fraction for desorption of toluene from humin and to quantify the sorption-desorption rates, the time courses of toluene sorption to compressed humin disks and to a thin humin film were investigated. The apparent diffusivity of toluene with humin disks ranges from 10(-8) to 10(-9) cm2/s and increases with temperature, based on the weight change of humin disks mounted on a microbalance and on the results simulated by use of a diffusion model. No detectable level of residual toluene was found after desorption, as revealed either by the gravimetric analysis or by the Fourier transform infrared (FTIR) spectrum obtained at either low or high humidity. The time scale for intrinsic vapor sorption without mass transfer hindrance is less than a few minutes with the thin film. All the results indicate that the sorption of toluene to humin is reversible and mainly diffusion controlled. This finding helps to better understand the sorption kinetics associated with humin and soil organic matter.

  1. PANI and Graphene/PANI Nanocomposite Films — Comparative Toluene Gas Sensing Behavior

    Directory of Open Access Journals (Sweden)

    Mitesh Parmar

    2013-12-01

    Full Text Available The present work discusses and compares the toluene sensing behavior of polyaniline (PANI and graphene/polyaniline nanocomposite (C-PANI films. The graphene–PANI ratio in the nanocomposite polymer film is optimized at 1:2. For this, N-methyl-2-pyrrolidone (NMP solvent is used to prepare PANI-NMP solution as well as graphene-PANI-NMP solution. The films are later annealed at 230 °C, characterized using scanning electron microscopy (SEM as well Fourier transform infrared spectroscopy (FTIR and tested for their sensing behavior towards toluene. The sensing behaviors of the films are analyzed at different temperatures (30, 50 and 100 °C for 100 ppm toluene in air. The nanocomposite C-PANI films have exhibited better overall toluene sensing behavior in terms of sensor response, response and recovery time as well as repeatability. Although the sensor response of PANI (12.6 at 30 °C, 38.4 at 100 °C is comparatively higher than that of C-PANI (8.4 at 30 °C, 35.5 at 100 °C, response and recovery time of PANI and C-PANI varies with operating temperature. C-PANI at 50 °C seems to have better toluene sensing behavior in terms of response time and recovery time.

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

    Science.gov (United States)

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

    1990-01-01

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

  3. Effect of relative humidity on the composition of secondary organic aerosol from the oxidation of toluene

    Science.gov (United States)

    Hinks, Mallory L.; Montoya-Aguilera, Julia; Ellison, Lucas; Lin, Peng; Laskin, Alexander; Laskin, Julia; Shiraiwa, Manabu; Dabdub, Donald; Nizkorodov, Sergey A.

    2018-02-01

    The effect of relative humidity (RH) on the chemical composition of secondary organic aerosol (SOA) formed from low-NOx toluene oxidation in the absence of seed particles was investigated. SOA samples were prepared in an aerosol smog chamber at SOA generated at 75 % RH compared to SOA generated under dry conditions. In a separate set of experiments, the particle mass concentrations were measured with a scanning mobility particle sizer (SMPS) at RHs ranging from SOA. The volatility distributions of the SOA compounds, estimated from the distribution of molecular formulas using the molecular corridor approach, confirmed that low-NOx toluene SOA became more volatile on average under high-RH conditions. In contrast, the effect of RH on SOA mass loading was found to be much smaller for high-NOx toluene SOA. The observed increase in the oligomer fraction and particle mass loading under dry conditions were attributed to the enhancement of condensation reactions, which produce water and oligomers from smaller compounds in low-NOx toluene SOA. The reduction in the fraction of oligomeric compounds under humid conditions is predicted to partly counteract the previously observed enhancement in the toluene SOA yield driven by the aerosol liquid water chemistry in deliquesced inorganic seed particles.

  4. High formation of secondary organic aerosol from the photo-oxidation of toluene

    Directory of Open Access Journals (Sweden)

    L. Hildebrandt

    2009-05-01

    Full Text Available Toluene and other aromatics have long been viewed as the dominant anthropogenic secondary organic aerosol (SOA precursors, but the SOA mass yields from toluene reported in previous studies vary widely. Experiments conducted in the Carnegie Mellon University environmental chamber to study SOA formation from the photo-oxidation of toluene show significantly larger SOA production than parameterizations employed in current air-quality models. Aerosol mass yields depend on experimental conditions: yields are higher under higher UV intensity, under low-NOx conditions and at lower temperatures. The extent of oxidation of the aerosol also varies with experimental conditions, consistent with ongoing, progressive photochemical aging of the toluene SOA. Measurements using a thermodenuder system suggest that the aerosol formed under high- and low-NOx conditions is semi-volatile. These results suggest that SOA formation from toluene depends strongly on ambient conditions. An approximate parameterization is proposed for use in air-quality models until a more thorough treatment accounting for the dynamic nature of this system becomes available.

  5. Toluene adsorption on VSbO4(110: a study of an electronic structure

    Directory of Open Access Journals (Sweden)

    Irigoyen B.L.

    2003-01-01

    Full Text Available The objective of this work is to electronically analyze toluene adsorption reactions on VSbO4(110. Thus, perpendicular and parallel toluene interactions on the different active sites of the oxide surface (O, Sb and V ions were studied. Adsorption energy was calculated using the ASED-MO theory, while the electronic analysis was performed with the YAEHMOP code. The electronic density of states (DOS of the VSbO4 cluster, modeled with a trirutile-type tetragonal supercell, resembles that of 3D solids with a rutile structure. However, due to the presence of vanadium, small peaks appear above the Fermi level. The DOS of toluene has several peaks resulting from the interaction of the aromatic ring with the methyl fragment, which changes when the adsorbate interacts with the oxide surface. The C-H bonds in the methyl fragment as well as the Cmethyl-Cphenyl bond weaken when some electronic density is removed. Also, hydrocarbon oxidation could weaken the p system of the aromatic ring. For toluene perpendicular adsorption (on the V site the calculations show a hybridization of those orbitals coming from the methyl fragment and the phenyl-methyl interaction energy region. After toluene parallel adsorption on Sb-V sites, the DOS shows an important broadening of some of the methyl and phenyl fragment orbitals. In addition, a study of the overlap population suggests that one of the H atoms of the methyl group can be abstracted with the participation of the Sb cation.

  6. Characterization and performance of a toluene-degrading biofilm developed on pumice stones

    Directory of Open Access Journals (Sweden)

    Sacceddu Pasquale

    2005-01-01

    Full Text Available Abstract Background Hydrocarbon-degrading biofilms in the treatment of contaminated groundwaters have received increasing attention due to the role played in the so-called "biobarriers". These are bioremediation systems in which a microbial consortium adherent to a solid support is placed across the flow of a contaminated plume, thus promoting biodegradation of the pollutant. Results A microbial consortium adherent to pumice granules (biofilm developed from a toluene-enriched microflora in a mini-scale system, following continuous supply of a mineral medium containing toluene, over a 12-month period. Observation by scanning electron microscopy, together with quantification of the biomass attached to pumice, evidenced the presence of abundant exopolymeric material surrounding the cells in the biofilm. Toluene removal monitored during 12-month operation, reached 99%. Identification of the species, based on comparative 16S ribosomal DNA (rDNA sequence analysis, revealed that Rhodococcus erythropolis and Pseudomonas marginalis were the predominant bacterial species in the microbial consortium. Conclusion A structurally complex toluene-degrading biofilm, mainly formed by Rhodococcus erythropolis and Pseudomonas marginalis, developed on pumice granules, in a mini-scale apparatus continuously fed with toluene.

  7. Removal of gaseous toluene and submicron aerosol particles using a dielectric barrier discharge reactor

    International Nuclear Information System (INIS)

    Byeon, Jeong Hoon; Park, Jae Hong; Jo, Yoon Shin; Yoon, Ki Young; Hwang, Jungho

    2010-01-01

    A lab-scale dielectric barrier discharge (DBD) reactor was fabricated, and gaseous and particulate contaminant removal tests were carried out under a range of DBD reactor operating conditions: applied voltage (5.0-8.5 kV), frequency (60-1000 Hz), upstream toluene concentration (50-200 ppm) and gas flow rate (1-5 L min -1 or 0.48-0.096 s of gas residence time). The results suggested that the toluene removal efficiency (at 1 L min -1 , 100 ppm) increased (up to ∼46%) either with increasing voltage (at 1000 Hz) or frequency (at 8.5 kV). The overall particle collection efficiency (at 1 L min -1 ) improved (up to ∼60%) with increasing voltage (at 1000 Hz) whereas the penetration of the particles increased (up to ∼40%) with increasing frequency (at 8.5 kV). The toluene removal efficiency (at 8.5 kV, 1000 Hz, 100 ppm) decreased (down to ∼29%) with increasing gas flow rate while the particle collection efficiency decreased slightly (maintaining ∼60%) regardless of the flow rate. In addition, the toluene removal efficiency (down to ∼41%) and carbon dioxide selectivity (down to ∼43%) decreased with increasing upstream toluene concentration (at 5 kV, 1000 Hz, 1 L min -1 ).

  8. Electrophilic and free radical nitration of benzene and toluene with various nitrating agents*

    Science.gov (United States)

    Olah, George A.; Lin, Henry C.; Olah, Judith A.; Narang, Subhash C.

    1978-01-01

    Electrophilic nitration of toluene and benzene was studied under various conditions with several nitrating systems. It was found that high orthopara regioselectivity is prevalent in all reactions and is independent of the reactivity of the nitrating agent. The methyl group of toluene is predominantly ortho-para directing under all reaction conditions. Steric factors are considered to be important but not the sole reason for the variation in the ortho/para ratio. The results reinforce our earlier views that, in electrophilic aromatic nitrations with reactive nitrating agents, substrate and positional selectivities are determined in two separate steps. The first step involves a π-aromatic-NO2+ ion complex or encounter pair, whereas the subsequent step is of arenium ion nature (separate for the ortho, meta, and para positions). The former determines substrate selectivity, whereas the latter determines regioselectivity. Thermal free radical nitration of benzene and toluene with tetranitromethane in sharp contrast gave nearly statistical product distributions. PMID:16592503

  9. Regioselective toluene nitration catalyzed with layered HNbMoO6

    Science.gov (United States)

    Hu, Li-Fang; Tang, Yuan; He, Jie; Chen, Kai; Lv, Wei

    2017-03-01

    HNbMoO6 layered oxide was obtained by the ion-exchange from LiNbMoO6 prepared by solid state reaction (SSR). The micro-structure, textural characteristics and acidity of the as-prepared catalyst were characterized by powder X-ray diffraction (XRD), laser Raman spectroscopy (LRS) and ammonia temperature- programmed desorption (NH3-TPD). Catalytic performance was evaluated in the regioselective nitration of toluene with a novel nitration system containing acetic anhydride and CCl4. The optimal nitration conditions comprise the application of 95 wt % HNO3, HNO3-to-toluene molar ratio of 2.5, catalyst pretreatment temperature of 503 K, reaction temperature of 313 K, and reaction time of 2.5 h. The toluene conversion rate and para-selectivity were also attributable to the strong acidity and the appropriate interlayer distance of the studied catalyst.

  10. A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method

    Directory of Open Access Journals (Sweden)

    Yong-Sang Kim

    2010-01-01

    Full Text Available Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2 pores with a diameter of 70~80 nm using this method. This thin film had a Pd/TiO2 nanoporous/SiO2/Si MIS layered structure with Pd-TiO2 as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO2 surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO2 interface work function, resulting in a change in the I-V characteristics.

  11. Toluene Oxidation by Non-Thermal Plasma Combined with Palladium Catalysts

    Directory of Open Access Journals (Sweden)

    Monica eMagureanu

    2013-06-01

    Full Text Available The oxidation of toluene in air was investigated using a dielectric barrier discharge (DBD combined with a Pd/Al2O3 catalyst. When using only plasma, rather low selectivity towards CO2 was obtained: 32-35%. By filling the DBD reactor with Pd/Al2O3 catalyst the CO2 selectivity was significantly enhanced (80-90%, however, a large amount of toluene was desorbed from the catalyst when the discharge was operated. By filling a quarter of the discharge gap with catalyst and placing the rest of the catalyst downstream of the plasma reactor, an important increase of CO2 selectivity (~75% and a 15% increase in toluene conversion were achieved as compared to the results with plasma alone. The catalyst exhibited a very good stability in this reaction.

  12. Non-invasive toluene sensor for early diagnosis of lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Rahul; Srivastava, Sudha, E-mail: sudha.srivastava@jiit.ac.in [Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307,Uttar Pradesh (India)

    2016-04-13

    Here we present, quantification of volatile organic compounds in human breath for early detection of lung cancer to increase survival probability. Graphene oxide nanosheets synthesized by modified Hummer’s method were employed as a sensing element to detect the presence of toluene in the sample. Optical and morphological characterization of synthesized nanomaterial was performed by UV-Visible spectroscopy and scanning electron microscopy (SEM) respectively. Spectroscopic assay shows a linearly decreasing intensity of GO absorption peak with increasing toluene concentration with a linear range from 0-200 pM. While impedimetric sensor developed on a graphene oxide nanosheetsmodified screen printed electrodes displayed a decreasing electron transfer resistance increasing toluene with much larger linear range of 0-1000 pM. Reported techniques are advantageous as these are simple, sensitive and cost effective, which can easily be extended for primary screening of other VOCs.

  13. Optical thermal sensor based on cholesteric film refilled with mixture of toluene and ethanol.

    Science.gov (United States)

    Li, Yong; Liu, Yanjun; Luo, Dan

    2017-10-16

    We demonstrate an optical thermal sensor based on cholesteric film refilled with mixture of toluene and ethanol. The thermal response mechanism is mainly based on the thermal expansion effect induce by toluene, where the ethanol is used for refractive index adjustment to determine the initial refection band position of cholesteric film. The ethanol-toluene mixture was used to adjust the color tunability with the temperature in relation with the habits of people (blue as cold, green as safe and red as hot). A broad temperature range of 86 °C and highly sensitivity of 1.79 nm/ °C are achieved in proposed thermal sensor, where the reflective color red-shifts from blue to red when environmental temperature increases from -6 °C to 80 °C. This battery-free thermal sensor possesses features including simple fabrication, low-cost, and broad temperature sensing range, showing potential application in scientific research and industry.

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

    Science.gov (United States)

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

    2009-12-01

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

  15. An experimental study on MRI and histopathologic findings of the brain in toluene inhaled rat

    International Nuclear Information System (INIS)

    Park, Dong Woo; Jeon, Seok Chol; Lee, Seung Ro; Kim, Yong Soo; Park, Choong Ki; Hahm, Chang-Kok; Baeck, Seung Kyung; Yang, Young Il

    1997-01-01

    To evaluate MRI and histopathologic findings of toluene inhalation in the acute and subacute stages in rat brain. Forty-eight Sprague-Dawley rats, weighing 200-300g, were divided into six groups:the control group, and five experimental groups each of eight rats, divided as follows, according to the concentration and duration of inhalation of toluene: 2500 ppm of toluence vapor for 2 hours only, 2 hours daily for 1 week, and 2 hours daily for 3 weeks;4000 ppm of toluence vapor for 2 hours only and 2 hours daily for 1 week. For all these five groups, a 0.02m 3 whole body exposure chamber was used. Spin echo and field echo(FE, gradient echo) MR images were obtained at 0.5T, and then histopathologic examination of the brain was performed. MR signal changes were statistically assessed for contrast to noise ratio(CNR). On T2-weighted MR images, the toluene-inhalation groups revealed diffuse hypointensity in the corpus striatum and thalamus, and diffuse hyperintensity in cerebral white matter, with statistically significant CNR change, compared with the control group. On T1-weighted and FE images, CNR differences in the corpus striatum, thalamus and cerebral white matter between the toluene inhalation groups were not statistically significant. Histopathologic study of these groups showed (1)neuronal degeneration such as shrinkage of neuronal cells and increase of the number of autophagosomes, (2)myelin degeneration and regeneration, and (3)focal axonal degeneration, In groups in which toluene inhalation was at higher concentrations and for longer, these phenomena were more extensive. As seen on MRI, toluene inhalation changes the signal intensity of the corpus striatum, the thalamus, and cerebral white matter. Neuronal, myelinic and axonal degeneration probably contribute to these signal changes

  16. Effect of relative humidity on the composition of secondary organic aerosol from the oxidation of toluene

    Directory of Open Access Journals (Sweden)

    M. L. Hinks

    2018-02-01

    Full Text Available The effect of relative humidity (RH on the chemical composition of secondary organic aerosol (SOA formed from low-NOx toluene oxidation in the absence of seed particles was investigated. SOA samples were prepared in an aerosol smog chamber at < 2 % RH and 75 % RH, collected on Teflon filters, and analyzed with nanospray desorption electrospray ionization high-resolution mass spectrometry (nano-DESI–HRMS. Measurements revealed a significant reduction in the fraction of oligomers present in the SOA generated at 75 % RH compared to SOA generated under dry conditions. In a separate set of experiments, the particle mass concentrations were measured with a scanning mobility particle sizer (SMPS at RHs ranging from < 2 to 90 %. It was found that the particle mass loading decreased by nearly an order of magnitude when RH increased from < 2 to 75–90 % for low-NOx toluene SOA. The volatility distributions of the SOA compounds, estimated from the distribution of molecular formulas using the molecular corridor approach, confirmed that low-NOx toluene SOA became more volatile on average under high-RH conditions. In contrast, the effect of RH on SOA mass loading was found to be much smaller for high-NOx toluene SOA. The observed increase in the oligomer fraction and particle mass loading under dry conditions were attributed to the enhancement of condensation reactions, which produce water and oligomers from smaller compounds in low-NOx toluene SOA. The reduction in the fraction of oligomeric compounds under humid conditions is predicted to partly counteract the previously observed enhancement in the toluene SOA yield driven by the aerosol liquid water chemistry in deliquesced inorganic seed particles.

  17. Densities, speeds of sound, and refractive indices of the ternary mixtures (toluene + methyl acetate + butyl acetate) and (toluene + methyl acetate + methyl heptanoate) at 298.15 K

    International Nuclear Information System (INIS)

    Mariano, Alejandra; Postigo, Miguel; Gonzalez-Salgado, Diego; Romani, Luis

    2007-01-01

    Density, ρ, speed of sound, u, and refractive index, n D , at 298.15 K and atmospheric pressure have been measured over the entire composition range for (toluene + methyl acetate + butyl acetate) and (toluene + methyl acetate + methyl heptanoate) systems. Excess molar volumes, V E , isentropic compressibility, κ s , isentropic compressibility deviations, Δκ s , and changes of refractive index on mixing, Δn D , for the above systems, have been calculated from experimental data and fitted to Cibulka, Singh et al., and Nagata and Sakura equations, standard deviations from the regression lines are shown. Geometrical solution models, Tsao and Smith, Kholer, Jacob and Fitzner, Rastogi et al. were also applied to predict ternary properties from binary contributions

  18. Organosilica Membrane with Ionic Liquid Properties for Separation of Toluene/H₂ Mixture.

    Science.gov (United States)

    Hirota, Yuichiro; Maeda, Yohei; Yamamoto, Yusuke; Miyamoto, Manabu; Nishiyama, Norikazu

    2017-08-03

    In this study, we present a new concept in chemically stabilized ionic liquid membranes: an ionic liquid organosilica (ILOS) membrane, which is an organosilica membrane with ionic liquid-like properties. A silylated ionic liquid was used as a precursor for synthesis. The permselectivity, permeation mechanism, and stability of the membrane in the H₂/toluene binary system were then compared with a supported ionic liquid membrane. The membrane showed a superior separation factor of toluene/H₂ (>17,000) in a binary mixture system based on a solution-diffusion mechanism with improved durability over the supported ionic liquid membrane.

  19. Efficacy of pentane, toluene, and benzene to support aerobic cometabolism of ethylene dibromide.

    Science.gov (United States)

    Danko, Anthony S; Leitão, Patrícia O; Verce, Matthew F; Freedman, David L

    2012-11-15

    The ability of pentane, benzene, and toluene to support aerobic cometabolism of ethylene dibromide (1,2-dibromoethane, EDB) was evaluated. A pentane enrichment culture cometabolized EDB, with a transformation capacity of 0.35 μmol EDB/mg biomass (66.2 μg EDB/mg biomass) in the absence of growth substrate. It also cometabolized EDB while actively growing on pentane. However, enrichment cultures grown on benzene or toluene could not cometabolize EDB, with or without their respective growth substrates. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Density measurements under pressure for the binary system 1-propanol plus toluene

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Andersen, Simon Ivar

    2005-01-01

    The density of the binary system composed of 1-propanol and toluene has been measured under pressure using a vibrating-tube densimeter. The measurements have been performed for four different compositions as well as the pure compounds at four temperatures in the range of (303.15 to 333.15) K...... but also due to the electron donor- acceptor-type formation of hydrogen bonding between the hydroxyl group of 1-propanol and the pi electrons of toluene because aromatic hydrocarbons can act as electron donors....

  1. Spectral Induced Polarization (SIP) measurements for monitoring toluene contamination in clayey soils

    Science.gov (United States)

    Ustra, A.; Slater, L. D.; Ntarlagiannis, D.

    2010-12-01

    The Spectral Induced Polarization (SIP) method has previously shown potential for detecting hydrocarbons in the subsurface when clay minerals are present. However, results from recent studies of soils containing hydrocarbon contaminants are inconclusive, and further research is needed. In an effort to better constrain the sensitivity of SIP to toluene contamination in clayey soils, samples consisting of mixtures of quartzitic sand and montmorillonite (5 and 10% by weight) were contaminated with varying amounts of toluene (5, 10 and 20% by weight) and saturated with sodium nitrate solution (0.003 mol/L). The SIP response of the various samples was monitored for a period of about 40 days. An important aspect of this experimental work was to minimize measurement errors related with the experimental set up and uncertainty in the interpretation of effects of hydrocarbon presence that will result from any variations in sample packing. Errors from the experimental setup (electrodes, sample holder and data acquisition device) varied from 0.02 mrad (at 0.01 Hz) to 9 mrad (at 1000 Hz), as determined from calibration measurements on water samples with known electrical properties. Variations associated with the packing effect (based on repeated sample packs) were from 0.1 mrad (at 0.01 Hz) to 11 mrad (at 1000 Hz). The real and imaginary conductivities at specified frequencies and the integral chargeability and time constant (obtained from a Debye decomposition fitting) were correlated to toluene and clay content. Repeated SIP measurements suggest that the toluene contaminated samples may take significant time to come into equilibrium. Low frequency SIP measurements are significantly related to toluene content only during early stages of contamination, when the dependence of SIP on clay concentration is apparently suppressed. At later time, progress towards a steady state SIP response (interpreted to indicate equilibrium surface chemistry) results in loss of a significant

  2. Influence of Gold on Hydrotalcite-like Compound Catalysts for Toluene and CO Total Oxidation

    Directory of Open Access Journals (Sweden)

    Eric Genty

    2013-12-01

    Full Text Available X6Al2HT500 hydrotalcites, where X represents Mg, Fe, Cu or Zn were synthetized and investigated before and after gold deposition for toluene and CO total oxidation reactions. The samples have been characterized by specific areas, XRD measurements and Temperature Programmed Reduction. Concerning the toluene total oxidation, the best activity was obtained with Au/Cu6Al2HT500 catalyst with T50 at 260 °C. However, catalytic behavior of Au/X6Al2HT500 sample in both reactions depends mainly on the nature of the support.

  3. Promotion of noise-induced cochlear injury by toluene and ethylbenzene in the rat.

    Science.gov (United States)

    Fechter, Laurence D; Gearhart, Caroline; Fulton, Sherry; Campbell, Jerry; Fisher, Jeffrey; Na, Kwangsam; Cocker, David; Nelson-Miller, Alisa; Moon, Patrick; Pouyatos, Benoit

    2007-08-01

    Ethylbenzene + toluene are known individually to have ototoxic potential at high exposure levels and with prolonged exposure times generally of 4-16 weeks. Both ethylbenzene + toluene are minor constituents of JP-8 jet fuel; this fuel has recently been determined to promote susceptibility to noise-induced hearing loss. Therefore, the current study evaluates the ototoxic potential of combined exposure to ethylbenzene + toluene exposure in a ratio calculated from the average found in three laboratories. Rats received ethylbenzene + toluene by inhalation and half of them were subjected simultaneously to an octave band of noise (OBN) of 93-95 dB. Another group received only the noise exposure which was designed to produce a small, but permanent auditory impairment while an unexposed control group was also included. In two separate experiments, exposures occurred either repeatedly on 5 successive days for 1 week or for 5 days on 2 successive weeks to 4000 mg/m(3) total hydrocarbons for 6 h based upon initial pilot studies. The concentration of toluene was 400 ppm and the concentration of ethylbenzene was 660 ppm. Impairments in auditory function were assessed using distortion product otoacoustic emissions and compound action potential testing. Following completion of these tests, the organs of Corti were dissected to permit evaluation of hair cell loss. The uptake and elimination of the solvents was assessed by harvesting key organs at two time points following ethylbenzene + toluene exposure from additional rats not used for auditory testing. Similarly, glutathione (GSH) levels were measured in light of suggestions that oxidative stress might result from solvent-noise exposures. Ethylbenzene + toluene exposure by itself at 4000 mg/m(3) for 6 h did not impair cochlear function or yield a loss of hair cells. However, when combined with a 93-dB OBN exposure combined solvent + noise did yield a loss in auditory function and a clear potentiation of outer hair cell death

  4. The Design of MnOx Based Catalyst in Post-Plasma Catalysis Configuration for Toluene Abatement

    Directory of Open Access Journals (Sweden)

    Zhiping Ye

    2018-02-01

    Full Text Available This review provides an overview of our present state of knowledge using manganese oxide (MnOx-based catalysts for toluene abatement in PPC (Post plasma-catalysis configuration. The context of this study is concisely sum-up. After briefly screening the main depollution methods, the principles of PPC are exposed based on the coupling of two mature technologies such as NTP (Non thermal plasma and catalysis. In that respect, the presentation of the abundant manganese oxides will be firstly given. Then in a second step the main features of MnOx allowing better performances in the reactions expected to occur in the abatement of toluene in PPC process are reviewed including ozone decomposition, toluene ozonation, CO oxidation and toluene total oxidation. Finally, in a last part the current status of the applications of PPC using MnOx on toluene abatement are discussed. In a first step, the selected variables of the hybrid process related to the experimental conditions of toluene abatement in air are identified. The selected variables are those expected to play a role in the performances of PPC system towards toluene abatement. Then the descriptors linked to the performances of the hybrid process in terms of efficiency are given and the effects of the variables on the experimental outcomes (descriptors are discussed. The review would serve as a reference guide for the optimization of the PPC process using MnOx-based oxides for toluene abatement.

  5. A PHYSIOLOGICALLY-BASED PHARMACOKINETIC MODEL FOR TOLUENE IN THE LONG EVANS RAT: BODY COMPOSITION AND PHYSICAL ACTIVITY.

    Science.gov (United States)

    A physiologically-based pharmacokinetic (PBPK) model for inhaled toluene was developed for Long-Evans rats as a component of an exposure-dose-response (EDR) model for volatile organic compounds. The PBPK model was needed to link airborne toluene exposure to its concentration in b...

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

    Science.gov (United States)

    Chee-Sanford, J C; Frost, J W; Fries, M R; Zhou, J; Tiedje, J M

    1996-01-01

    A toluene-degrading denitrifier, Azoarcus tolulyticus Tol-4, was one of eight similar strains isolated from three petroleum-contaminated aquifer sediments. When the strain was grown anaerobically on toluene, 68% of the carbon from toluene was found as CO2 and 30% was found as biomass. Strain Tol-4 had a doubling time of 4.3 h, a Vmax of 50 micromol x min-1 x g of protein-1, and a cellular yield of 49.6 g x mol of toluene-1. Benzoate appeared to be an intermediate, since F-benzoates accumulated from F-toluenes and [14C]benzoate was produced from [14C]toluene in the presence of excess benzoate. Two metabolites, E-phenylitaconic acid (1 to 2%) and benzylsuccinic acid (toluene, [14C]acetate, and cinnamic acid. Evidence for anaerobic toluene metabolism by methyl group oxidation was not found, since benzylsuccinic acid and E-phenylitaconic acid were not detected after incubation with benzylalcohol and benzaldehyde, nor were benzylalcohol and benzaldehyde detected even in 14C trapping experiments. PMID:8975623

  7. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE USING PATTERN ELICITED VISUAL EVOKED POTENTIALS.

    Science.gov (United States)

    In vitro studies have demonstrated that toluene disrupts the function of NMDA-glutamate receptors, as well as other channels. This has led to the hypothesis that effects on NMDA receptor function may contribute to toluene neurotoxicity, CNS depression, and altered visual evoked ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

  9. In vitro metabolism of [14C]-toluene by human and rat liver microsomes and liver slices

    International Nuclear Information System (INIS)

    Chapman, D.E.; Moore, T.J.; Michener, S.R.; Powis, G.

    1990-01-01

    Toluene metabolites produced by liver microsomes from six human donors included benzylalcohol (Balc), benzaldehyde (Bald) and benzoic acid (Bacid). Microsomes from only one human donor metabolized toluene to p-cresol and o-cresol. Human liver microsomes also metabolized Balc to Bald. Balc metabolism required NADPH, was inhibited by carbon monoxide, and was decreased at a buffer pH of 10. Balc metabolism was not inhibited by ADP-ribose or sodium azide. These results suggest that cytochrome P450 is responsible for the in vitro metabolism of Balc by human liver microsomes. Toluene metabolites formed by human liver slices and released into the incubation media included hippuric acid, and Bacid. Cresols or cresol-conjugates were not detected in liver slice incubation media from any human donor. Toluene metabolism by human liver was compared to metabolism by comparable liver preparations from male Fischer F344 rats. Rates of toluene metabolism by human liver microsomes and liver slices were 9-fold and 1.3-fold greater than for rat liver, respectively. Covalent binding of toluene to human liver microsomes and liver slices was 21-fold and 4-fold greater than for comparable rat liver preparations. Covalent binding of toluene to human microsomes required NADPH, was significantly decreased by coincubation with 4 mM cysteine or 4 mM glutathione, and radioactivity associated with microsomes was decreased by subsequent digestion of microsomes with protease. These results suggest that toluene metabolism and covalent binding of toluene are underestimated if the male Fischer 344 rat is used as a model for human toluene metabolism

  10. Biocatalytic conversion of ethylene to ethylene oxide using an engineered toluene monooxygenase.

    Science.gov (United States)

    Carlin, D A; Bertolani, S J; Siegel, J B

    2015-02-11

    Mutants of toluene o-xylene monooxygenase are demonstrated to oxidize ethylene to ethylene oxide in vivo at yields of >99%. The best mutant increases ethylene oxidation activity by >5500-fold relative to the native enzyme. This is the first report of a recombinant enzyme capable of carrying out this industrially significant chemical conversion.

  11. AGING AND SUSCEPTIBILITY TO TOLUENE IN RATS: A PHARMACOKINETIC, BIOMARKER, AND PHYSIOLOGICAL APPROACH.

    Science.gov (United States)

    Aging adults are a growing segment of the U.S. population and are likely to exhibit increased susceptibility to many environmental toxicants. However, there is little information on the susceptibility of the aged to toxicants. The toxicity of toluene has been well characterized i...

  12. Removal of Toluene over NaX Zeolite Exchanged with Cu2+

    Directory of Open Access Journals (Sweden)

    Douglas Romero

    2015-09-01

    Full Text Available Toluene is a major air pollutant emitted from painting and metal coating processes and might have some health effects. Adsorption and catalytic complete oxidation are promising ways to retain or convert toluene into harmless products. The present work aims to develop a bifunctional material which can be used as an adsorbent and catalyst for low-temperature toluene removal. Copper zeolites were obtained by exchanging the sodium in the parent NaX zeolite with copper from aqueous solutions of Cu(NO32∙2.5H2O. Several characterization techniques, H2-TPR, XPS, XRD and N2 physisorption, were used in order to evaluate the redox, surface, structural and textural properties of the materials, respectively. The various materials were tested in adsorption and catalytic processes. The sample with low copper content (1 wt. % exhibited promising features in terms of toluene adsorption capacity and total oxidation. The results can be correlated to the presence of micropores and well-dispersed CuO species.

  13. The effect of MFI zeolite lamellar and related mesostructures on toluene disproportionation and alkylation

    Czech Academy of Sciences Publication Activity Database

    Jo, Ch.; Ryoo, R.; Žilková, Naděžda; Vitvarová, Dana; Čejka, Jiří

    2013-01-01

    Roč. 3, č. 8 (2013), s. 2119-2129 ISSN 2044-4753 R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : Adsorption measurement * Alkylation of toluene * Isopropyl alcohols Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.760, year: 2013

  14. Chemostat-based proteomic analysis of toluene-affected Pseudomonas putida S12

    NARCIS (Netherlands)

    Volkers, R.J.M.; Jong, A.L. de; Hulst, A.G.; Baar, B.L.M. van; Bont, J.A.M. de; Wery, J.

    2006-01-01

    The aim of this study was to assess the cellular response of the solvent-tolerant Pseudomonas putida S12 to toluene as the single effector. Proteomic analysis (two-dimensional difference-in-gel-electrophoresis) was used to assess the response of P. putida S12 cultured in chemostats. This approach

  15. Response of solvent-exposed printers and unexposed controls to six-hour toluene exposure

    DEFF Research Database (Denmark)

    Bælum, Jesper; Andersen, I B; Lundqvist, G R

    1985-01-01

    The acute effects of toluene were studied in 43 male printers and 43 control subjects matched according to sex, age, educational level, and smoking habits. The mean age of the subjects was 36 (range 29-50) years. The printers had been exposed to solvents for 9 to 25 years during employment at flexo...

  16. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    Science.gov (United States)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-02-01

    Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  17. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    International Nuclear Information System (INIS)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-01-01

    Results are presented from experimental studies of decomposition of toluene (C 6 H 5 CH 3 ) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C 6 H 5 CH 3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N 2 : O 2 : H 2 O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C 6 H 5 CH 3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C 6 H 5 CH 3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  18. Selective Production of Toluene from Biomass-Derived Isoprene and Acrolein.

    Science.gov (United States)

    Dai, Tao; Li, Changzhi; Zhang, Bo; Guo, Haiwei; Pan, Xiaoli; Li, Lin; Wang, Aiqin; Zhang, Tao

    2016-12-20

    Toluene is a basic chemical that is currently produced from petroleum resources. In this paper, we report a new route for the effective synthesis of toluene from isoprene and acrolein, two reactants readily available from biomass, through a simple two-step reaction. The process includes Diels-Alder cycloaddition of isoprene and acrolein in a Zn-containing ionic liquid at room temperature to produce methylcyclohex-3-enecarbaldehydes (MCHCAs) as intermediates, followed by M (M=Pt, Pd, Rh)/Al 2 O 3 -catalyzed consecutive dehydrogenation-decarbonylation of the MCHCAs at 573 K to generate toluene with an overall yield up to 90.7 %. Model reactions indicated that a synergistic inductive effect of the C=C double bond and the aldehyde group in MCHCA plays a key role in initiating the consecutive dehydrogenation-decarbonylation, and that methyl benzaldehydes are the key intermediates in the gas-phase transformation of MCHCAs. Microcalorimetric adsorption of CO on different catalysts showed that decarbonylation of the substrate occurs more likely on the strong adsorption sites. To the best of our knowledge, it is the first report of Pt/Al 2 O 3 -catalyzed consecutive dehydrogenation-decarbonylation of a given compound in one reactor. This work provides a highly efficient and environmental friendly route to toluene by utilizing two compounds that can be prepared from biomass. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Comparison of toluene removal in air at atmospheric conditions by different corona discharges.

    Science.gov (United States)

    Schiorlin, Milko; Marotta, Ester; Rea, Massimo; Paradisi, Cristina

    2009-12-15

    Different types of corona discharges, produced by DC of either polarity (+/-DC) and positive pulsed (+pulsed) high voltages, were applied to the removal of toluene via oxidation in air at room temperature and atmospheric pressure. Mechanistic insight was obtained through comparison of the three different corona regimes with regard to process efficiency, products, response to the presence of humidity and, for DC coronas, current/voltage characteristics coupled with ion analysis. Process efficiency increases in the order +DC Atmospheric Pressure Chemical Ionization-Mass Spectrometry), provides a powerful rationale for interpreting current/voltage characteristics of DC coronas. All experimental findings are consistent with the proposal that in the case of +DC corona toluene oxidation is initiated by reactions with ions (O(2)(+*), H(3)O(+) and their hydrates, NO(+)) both in dry as well as in humid air. In contrast, with -DC no evidence is found for any significant reaction of toluene with negative ions. It is also concluded that in humid air OH radicals are involved in the initial stage of toluene oxidation induced both by -DC and +pulsed corona.

  20. TOXICITY PATHWAY ANALYSIS IN AGING BROWN NORWAY RAT BRAIN FOLLOWING ACUTE TOLUENE EXPOSURE

    Science.gov (United States)

    The influence of aging on susceptibility to environmental stressors is poorly understood. To investigate the contribution of different life stages on response to toxicants, we examined the effects of acute exposure by oral gavage of the volatile organic solvent toluene (0.00, 0.3...

  1. AGE-RELATED TOXICITY PATHWAY ANALYSIS IN BROWN NORWAY RAT BRAIN FOLLOWING ACUTE TOLUENE EXPOSURE

    Science.gov (United States)

    The influence of aging on susceptibility to environmental exposures is poorly understood. To investigate-the contribution of different life stages on response to toxicants, we examined the effects of an acute exposure to the volatile organic compound, toluene (0.0 or 1.0 g/kg), i...

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

    Science.gov (United States)

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

    2011-01-30

    The catalytic oxidation of two-component VOC mixtures (ethanol, ethyl acetate and toluene) was studied over cryptomelane. Remarkable mixture effects were observed on the activity and the selectivity. Toluene inhibits both ethyl acetate and ethanol oxidation, this effect being more evident in the case of ethyl acetate. For instance, the temperature for 100% conversion is about 210 °C when ethyl acetate is oxidised alone, and 250 °C or higher, when it is oxidised in mixtures with toluene. On the contrary, toluene oxidation is only slightly inhibited by the presence of ethyl acetate, while the presence of ethanol has a promoting effect. Concerning the mixtures of ethyl acetate and ethanol, both compounds have a mutual inhibitory effect, which is more evident in the case of ethyl acetate (the temperature for 100% conversion of ethyl acetate is about 45 °C higher when ethyl acetate is oxidised in mixtures with ethanol, while in the case of ethanol the corresponding increase is only 10 °C). Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Biocatalytic conversion of ethylene to ethylene oxide using an engineered toluene monooxygenase

    Energy Technology Data Exchange (ETDEWEB)

    Carlin, DA; Bertolani, SJ; Siegel, JB

    2015-01-01

    Mutants of toluene o-xylene monooxygenase are demonstrated to oxidize ethylene to ethylene oxide in vivo at yields of >99%. The best mutant increases ethylene oxidation activity by >5500-fold relative to the native enzyme. This is the first report of a recombinant enzyme capable of carrying out this industrially significant chemical conversion.

  4. Adsorption of di-2-ethylhexylphosphoric acid from toluene the interface with inorganic salt aqueous solutions

    International Nuclear Information System (INIS)

    Fajnshtejn, E.V.; Popov, A.N.

    1990-01-01

    Interfacial tension in the system toluene solution of di-2-ethylhexylphosphoric acid HDEHP-aqueous solutions of inorganic salts has been measured by the drop volume method. The ion-exchange constants in the monolayers formed by HDEHP and alkaline-earth metals have been measured

  5. Extraction of uranium (VI) from nitric acid with N-decanoyl pyrrolidine (DPOD) in toluene

    International Nuclear Information System (INIS)

    Han Jingtian; Sun Guoxin; Bao Borong

    1999-01-01

    The extraction behaviors of uranium (VI) from nitric acid by N-decanoyl pyrrolidine (DPOD) in toluene has been studied at varying concentrations of nitric acid, extractant, salting-out agent LiNO 3 and at different temperatures. The mechanism of extraction is discussed in the light of the results obtained

  6. Degree of branching in hyperbranched poly(glycerol-co-diacid)s synthesized in toluene

    Science.gov (United States)

    Hyperbranched polymers were synthesized by using a Lewis acid (dibutyltin(IV)oxide) to catalyze the polycondensation of glycerol with either succinic acid (n (aliphatic chain length)=2), glutaric acid (n=3) or azelaic acid (n=7) in toluene. These are the first examples of diacid-glycerol hyperbranc...

  7. 75 FR 52768 - Withdrawal of Approval of New Animal Drug Applications; Dichlorophene and Toluene Capsules

    Science.gov (United States)

    2010-08-27

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Withdrawal of Approval of New Animal Drug Applications... use of dichlorophene and toluene deworming capsules for cats and dogs. In a final rule published...

  8. The extraction constant of mercury(II) o-o'-dimethyldithizonate into toluene

    NARCIS (Netherlands)

    Jütte, B.A.H.G.; Agterdenbos, J.; Welle, R.A. van der

    An attempt was made to determine spectrophotometrically the extraction constant of mercury(II) o-o'-dimethyldithizonate into toluene by means of a known excess of iodide as a masking agent. The results found, however, could not be explained by a simple reaction between mercury(II)

  9. Diels–Alder cycloaddition of 2-methylfuran and ethylene for renewable toluene

    Energy Technology Data Exchange (ETDEWEB)

    Green, Sara K.; Patet, Ryan E.; Nikbin, Nima; Williams, C. Luke; Chang, Chun-Chih; Yu, Jingye; Gorte, Raymond J.; Caratzoulas, Stavros; Fan, Wei; Vlachos, Dionisios G.; Dauenhauer, Paul J.

    2016-01-01

    Diels–Alder cycloaddition of biomass-derived 2-methylfuran and ethylene provides a thermochemical pathway to renewable toluene. In this work, the kinetics and reaction pathways of toluene formation have been evaluated with H-BEA and Sn-BEA catalysts. Kinetic analysis of the main reaction chemistries reveals the existence of two rate-controlling reactions: (i) Diels–Alder cycloaddition of 2-methylfuran and ethylene where the production rate is independent of the Brønsted acid site concentration, and (ii) dehydration of the Diels–Alder cycloadduct where the production rate is dependent on the Brønsted acid site concentration. Application of a reduced kinetic model supports the interplay of these two regimes with the highest concentration of toluene measured at a catalyst loading equal to the transition region between the two kinetic regimes. Selectivity to toluene never exceeded 46%, as 2-methylfuran was consumed by several newly identified reactions to side products, including dimerization of 2-methylfuran, the formation of a trimer following hydrolysis and ring-opening of 2-methylfuran, and the incomplete dehydration of the Diels–Alder cycloadduct of 2-methylfuran and ethylene.

  10. Molecular interactions in the complexes of toluene with butyronitrile: A DFT approach

    Science.gov (United States)

    Karthick, N. K.; Arivazhagan, G.

    2018-04-01

    Density Functional Theory (DFT) has been employed to investigate the self association of butyronitrile and the heterointeractions in the 1:2 (toluene: butyronitrile) and 1:1 complexes of toluene with butyronitrile. For this investigation the B3LYP functional with Grimme's dispersion correction (D3) term and ωB97XD functionals were used. The theoretical frequency analysis shows the unsuitability of B3LYP with D3 for the present investigation. Therefore, Natural Bonding Orbital analysis was done at the functional ωB97XD. It is found through this work that only the methylene hydrogens of butyronitrile are responsible for the self association among the butyronitrile molecules. In 1:1 complex, the red shift in the butyronitrile methyl asymmetric stretching mode is not due to the active participation of this group in heterointeractions and it is solely due to the other interactions happening in its vicinity. Only the interaction (TOL) C - H ⋯ N(BN) is present in the complex. In 1:2 complex the butyronitrile methyl/methylene hydrogens interact with the delocalized electron cloud of toluene and the toluene hydrogens interact with the butyronitrile nitrogen. Comparison of interaction energies shows that the stability of 1:2 complex is more than that of butyronitrile dimer and 1:1 complex.

  11. Renal effects of acute exposure to toluene. A controlled clinical trial

    DEFF Research Database (Denmark)

    Nielsen, H K; Krusell, Lars Romer; Bælum, Jesper

    1985-01-01

    Urinary excretion rates of beta 2-microglobulin and albumin were measured in 43 male printing trade workers and 43 age-matched male controls before and during exposure to toluene, 382 mg/m3, for 6 1/2 hours in a climate chamber. There were no significant changes in renal excretion rates of albumin...

  12. Effects of Acute Toluene Toxicity on Different Regions of Rabbit Brain

    Directory of Open Access Journals (Sweden)

    Mehmet Demır

    2017-01-01

    Full Text Available The acute phase effects of toluene on the brain have been investigated in this study using rabbit brain via histopathological, immunohistochemical, and biochemical methods. A total of 20 male rabbits were used as control and experimental groups. Moreover, nerve growth factor (NGF, tumor necrosis factor-alpha (TNF-alpha, dopamine (DA, and glial fibrillary acidic protein (GFAP tests were performed in order to designate the severity of the biochemical damage. In the biochemical evaluation of the prefrontal cortex, hippocampus, hypothalamus, substantia nigra, and entorhinal cortex, the TNF-alpha levels in the brain were found to be significantly higher than in the control group. Levels of dopamine, secreted from the substantia nigra, nerve growth factor (NGF developed from the hippocampal neurons, and GFAP, secreted from astrocyte cells, were detected to be significantly lower in the toluene-administration group than in the control group (p<0.05. In addition, areas of focal vacuolar degeneration (abscess formation, gliosis, and perivascular demyelination, many pyknotic cells and necrosis were observed. In the toluene-administration group compared to the control group, distinct excessive expansions of the blood vessels and severe degeneration in the structure of cells and also dispersed cell borders were observed. Furthermore, abnormal malformations of the nuclei structure of the oligodendrocyte cells were seen. Bodies of the sequential neurons of the hippocampus in the toluene-administration group were distinctly structurally damaged compared to the control group. In addition, cytoplasm of the cortex cell showed serious immune reactivity in the experimental group.

  13. Chemical characterisation of semi-volatile and aerosol compounds from the photooxidation of toluene and NOx

    Science.gov (United States)

    White, Stephen J.; Jamie, Ian M.; Angove, Dennys E.

    2014-02-01

    The chemical composition of a gas phase and secondary organic aerosol (SOA) mixture from toluene photooxidation in NOx was determined. Aerosol from toluene photooxidation was generated in a smog chamber and was collected onto glass fibre filters along with those gas phase compounds which adhered to the filter. The filter bound organic material was extracted, derivatised with O-2,3,4,5,6-pentafluorobenzyl hydroxylamine (PFBHA) and N,O-bistrimethylsilyl-trifluoroacetamide (BSTFA), then analysed using gas chromatography-mass spectrometry (GC-MS). Compound identification was aided by the use of isotopically-labelled toluene. The effect of humidity on product formation was investigated by raising water vapour concentration in one experiment. Sixty compounds were identified, of which twenty had not been identified from toluene photooxidation previously. Small carboxylic acids and dicarbonyls provided the highest proportion of identifiable compounds by relative response. The use of water to extract the filter samples resulted in much higher relative responses for oxocarboxylic acids, such as glyoxylic acid and pyruvic acid, than has been observed in previous studies. The formation of levulinic acid was determined to be due to the reaction of water with aromatic photooxidation products in the gas phase or particle phase of the chamber experiment. Nuclear magnetic resonance (NMR) was used to determine the functional groups of water-extracted organic material, which indicated that the water-soluble components were comprised of compounds which contain similar functional groups, primarily alcohols and carboxylic acids.

  14. Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

    Science.gov (United States)

    Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

    2013-01-01

    The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

  15. EFFECT OF AGING ON THE CARDIOVASCULAR AND THERMOREGULATORY RESPONSE TO TOLUENE IN THE BROWN NORWAY RATS.

    Science.gov (United States)

    Since the proportion of aged in the U.S. will expand markedly for the next several decades, the U.S.EPA is assessing if the aged are more susceptible to environmental toxicants. The neurotoxicity of toluene (TOL) has been well characterized in young adults but has not been studie...

  16. Rotavirus Symptoms

    Science.gov (United States)

    ... Search The CDC Cancel Submit Search The CDC Rotavirus Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Rotavirus Home About Rotavirus Symptoms Transmission Prevention Treatment Photos ...

  17. Diphtheria Symptoms

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search The CDC Diphtheria Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Diphtheria Home About Diphtheria Causes and Transmission Symptoms Complications ...

  18. Experimental and kinetic modeling investigation of rich premixed toluene flames doped with n-butanol.

    Science.gov (United States)

    Li, Yuyang; Yuan, Wenhao; Li, Tianyu; Li, Wei; Yang, Jiuzhong; Qi, Fei

    2018-02-09

    n-Butanol is a promising renewable biofuel and has a lot of advantages as a gasoline additive compared with ethanol. Though the combustion of pure n-butanol has been extensively investigated, the chemical structures of large hydrocarbons doped with n-butanol, especially for aromatic fuels, are still insufficiently understood. In this work, rich premixed toluene/n-butanol/oxygen/argon flames were investigated at 30 Torr with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The blending ratio of n-butanol was varied from 0 to 50%, while the equivalence ratio was maintained at a quite rich value (1.75) for the purpose of studying the influence of n-butanol on the aromatic growth process. Flame species including radicals, reactive molecules, isomers and polycyclic aromatic hydrocarbons (PAHs) were identified and their mole fraction profiles were measured. A kinetic model of toluene/n-butanol combustion was developed from our recently reported toluene and n-butanol models. It is observed that the production of most toluene decomposition products and larger aromatics was suppressed as the blending ratio of n-butanol increases. Meanwhile, the addition of n-butanol generally enhanced the formation of most observed C 2 -C 4 hydrocarbons and C 1 -C 4 oxygenated species. The rate of production (ROP) analysis and experimental observations both indicate that the interaction between toluene and n-butanol in their decomposition processes mainly occurs at the formation of small intermediates, e.g. acetylene and methyl. In particular, the interaction between toluene and n-butanol in methyl formation influences the formation of large monocyclic aromatics such as ethylbenzene, styrene and phenylacetylene, making their maximum mole fractions decay slowly upon increasing the blending ratio of n-butanol compared with toluene and benzyl. The increase of the blending ratio of n-butanol reduces the formation of key PAH precursors such as benzyl, fulvenallenyl

  19. IL-4 and IL-5 Secretions Predominate in the Airways of Wistar Rats Exposed to Toluene Diisocyanate Vapor

    Directory of Open Access Journals (Sweden)

    Kouame Kouadio

    2014-01-01

    Full Text Available ObjectivesWe established a Wistar rat model of asthma caused by toluene diisocyanate (TDI exposure, and investigated the relationship between TDI exposure concentrations and respiratory hypersensitivity, airway inflammation, and cytokine secretions in animals, to better understand the mechanism of TDI induced occupational asthma.MethodsWistar rats were exposed to two different concentrations of TDI vapor four hours a day for five consecutive days. Bronchoalveolar lavage (BAL was performed, and differential leucocytes from the BAL fluid were analyzed. Lung histopathological examination was carried out to investigate the inflammatory status in the airways. Production of cytokines interleukin (IL-4 and IL-5 productions in the BAL fluid in vivo was determined with enzyme-linked immunosorbent assay kits.ResultsThe TDI-exposed rats exhibited greater airway hypersensitivity symptoms than the control rats. The BAL differential cell count and lung histopathological examination demonstrated that inflammation reactions were present in both the central and peripheral airways, characterized with marked infiltration of eosinophils in the TDI-exposed rats. The cytokine assay showed that IL-4 and IL-5 were predominantly produced in the BAL fluid in vivo.ConclusionsThese findings imply that TDI exposure concentrations may greatly affect the occurrence and extent of inflammatory events and that Th2 type cytokines may play an important role in the immunopathogenesis of TDI-induced occupational respiratory hypersensitivity.

  20. Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition

    International Nuclear Information System (INIS)

    Jothiramalingam, R.; Wang, M.K.

    2007-01-01

    The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R 2 and standard error. The goodness to the linear fit was observed for Elovich model with high R 2 (≥0.9477) value

  1. Mixing-controlled biodegradation in a toluene plume — Results from two-dimensional laboratory experiments

    Science.gov (United States)

    Bauer, Robert D.; Maloszewski, Piotr; Zhang, Yanchun; Meckenstock, Rainer U.; Griebler, Christian

    2008-02-01

    Various abiotic and biotic processes such as sorption, dilution, and degradation are known to affect the fate of organic contaminants, such as petroleum hydrocarbons in saturated porous media. Reactive transport modeling of such plumes indicates that the biodegradation of organic pollutants is, in many cases, controlled by mixing and therefore occurs locally at the plume's fringes, where electron donors and electron-acceptors mix. Herein, we aim to test whether this hypothesis can be verified by experimental results obtained from aerobic and anaerobic degradation experiments in two-dimensional sediment microcosms. Toluene was selected as a model compound for oxidizable contaminants. The two-dimensional microcosm was filled with quartz sand and operated under controlled flow conditions simulating a contaminant plume in otherwise uncontaminated groundwater. Aerobic degradation of toluene by Pseudomonas putida mt-2 reduced a continuous 8.7 mg L - 1 toluene concentration by 35% over a transport distance of 78 cm in 15.5 h. In comparison, under similar conditions Aromatoleum aromaticum strain EbN1 degraded 98% of the toluene infiltrated using nitrate (68.5 ± 6.2 mg L - 1 ) as electron acceptor. A major part of the biodegradation activity was located at the plume fringes and the slope of the electron-acceptor gradient was steeper during periods of active biodegradation. The distribution of toluene and the significant overlap of nitrate at the plume's fringe indicate that biokinetic and/or microscale transport processes may constitute additional limiting factors. Experimental data is corroborated with results from a reactive transport model using double Monod kinetics. The outcome of the study shows that in order to simulate degradation in contaminant plumes, detailed data sets are required to test the applicability of models. These will have to deal with the incorporation of existing parameters coding for substrate conversion kinetics and microbial growth.

  2. Assessment of benzene and toluene emissions from automobile exhaust in Bangkok.

    Science.gov (United States)

    Muttamara, S; Leong, S T; Lertvisansak, I

    1999-07-01

    The use of unleaded gasoline, together with an increase in the number of vehicles in Bangkok, has significantly influenced benzene and toluene concentrations in vehicular emissions and contributes to the air pollution problem. As a matter of practical necessity, a quick test program is done for the measurement of emission concentrations/rates for vehicles driven on the road. Exhaust emission measurement at idle mode was conducted in a fleet of 12 vehicles of different model years and manufacturers. The study revealed that the benzene and toluene concentrations in the exhaust effluent averaged 4.4-22.02 and 12.24-44.75 mg/m3, respectively for 1990-1992 cars and decreased to 0.76-4.14 and 0.89-6.26 mg/m3, respectively for 1994-1995 cars. In another study, exhaust emission measurement on a chassis dynamometer was carried out in a fleet of nine selected, in-use cars. It was observed that benzene and toluene emission rates were considerably higher-in the range of 70.84-85.82 and 354.15- 429.00 mg/km, respectively, for 1990-1991 model year cars. Lower benzene and toluene emission rates of 0.43-95.07 and 2. 15-475.35 mg/km, respectively, were represented by newer cars with model years 1994-1995. These results indicated that there was a significant increase in benzene and toluene emission concentrations and rates with increasing car mileage and model year. The finding also revealed that only 28% of the tested vehicles complied to the approved emission standard. Copyright 1999 Academic Press.

  3. Benzene and toluene in the surface air of northern Eurasia from TROICA-12 campaign along the Trans-Siberian Railway

    Science.gov (United States)

    Skorokhod, Andrey I.; Berezina, Elena V.; Moiseenko, Konstantin B.; Elansky, Nikolay F.; Belikov, Igor B.

    2017-05-01

    Volatile organic compounds (VOCs) were measured by proton transfer reaction mass spectrometry (PTR-MS) on a mobile laboratory in a transcontinental TROICA-12 (21 July-4 August 2008) campaign along the Trans-Siberian Railway from Moscow to Vladivostok. Surface concentrations of benzene (C6H6) and toluene (C7H8) along with non-methane hydrocarbons (NMHCs), CO, O3, SO2, NO, NO2 and meteorology are analyzed in this study to identify the main sources of benzene and toluene along the Trans-Siberian Railway. The most measurements in the TROICA-12 campaign were conducted under low-wind/stagnant conditions in moderately ( ˜ 78 % of measurements) to weakly polluted ( ˜ 20 % of measurements) air directly affected by regional anthropogenic sources adjacent to the railway. Only 2 % of measurements were identified as characteristic of highly polluted urban atmosphere. Maximum values of benzene and toluene during the campaign reached 36.5 and 45.6 ppb, respectively, which is significantly less than their short-term exposure limits (94 and 159 ppb for benzene and toluene, respectively). About 90 % of benzene and 65 % of toluene content is attributed to motor vehicle transport and 10 and 20 %, respectively, provided by the other local- and regional-scale sources. The highest average concentrations of benzene and toluene are measured in the industrial regions of the European Russia (up to 0.3 and 0.4 ppb for benzene and toluene, respectively) and south Siberia (up to 0.2 and 0.4 ppb for benzene and toluene, respectively). Total contribution of benzene and toluene to photochemical ozone production along the Trans-Siberian Railway is about 16 % compared to the most abundant organic VOC - isoprene. This contribution, however, is found to be substantially higher (up to 60-70 %) in urbanized areas along the railway, suggesting an important role of anthropogenic pollutant sources in regional ozone photochemistry and air quality.

  4. Biodegradation of ortho-Cresol by a Mixed Culture of Nitrate-Reducing Bacteria Growing On Toluene

    DEFF Research Database (Denmark)

    Flyvbjerg, John; Jørgensen, Claus; Arvin, Erik

    1993-01-01

    of toluene metabolized, with an average yield of 0.47 mg of o-cresol degraded per mg of toluene metabolized. Experiments with (ring-U-14C)o-cresol indicated that about 73% of the carbon from degraded o-cresol was mineralized to CO-2 and about 23% was assimilated into biomass after the transient accumulation...... o-cresol by a cometabolic mechanism in which the enzymes necessary for the degradation of o-cresol are induced by toluene and not by o-cresol....

  5. Biocomplementation of SVE to achieve clean up goals in soils contaminated with toluene and xylene

    DEFF Research Database (Denmark)

    Soares, Antonio; Pinho, Maria Teresa; Albergaria, José Tomás

    2013-01-01

    aimed to study the combination of these two technologies in order to verify the achievement of the legal clean-up goals in soil remediation projects involving seven different simulated soils separately contaminated with toluene and xylene. The remediations consisted of the application of SVE followed...... by biostimulation. The results show that the combination of these two technologies is effective and manages to achieve the clean-up goals imposed by the Spanish Legislation. Under the experimental conditions used in this work, SVE is sufficient for the remediation of soils, contaminated separately with toluene...... and xylene, with organic matter contents (OMC) below 4 %. In soils with higher OMC, the use of BR, as a complementary technology, and when the concentration of contaminant in the gas phase of the soil reaches values near 1 mg/L, allows the achievement of the clean-up goals. The OMC was a key parameter...

  6. Viscosity of magnetite–toluene nanofluids: Dependence on temperature and nanoparticle concentration

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rahul [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States); Sanchez, Oswaldo [Department of Mathematical Sciences, Morningside College, Sioux City, IA (United States); Ghosh, Suvojit [Department of Engineering Physics, McMaster University, Hamilton, ON (Canada); Kadimcherla, Naveen [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States); Sen, Swarnendu [Department of Mechanical Engineering, Jadavpur University, Kolkata, West Bengal (India); Balasubramanian, Ganesh, E-mail: bganesh@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States)

    2015-10-23

    Highlights: • Viscosity of magnetite in toluene nanofluid increases monotonically with particle concentration. • Clusters formed at higher particle concentration are monodisperse. • With increasing temperature, viscosity decreases due less fraction of immobile fluid molecules. - Abstract: We examine the dependence of the viscosity of nanofluids, comprised of magnetite nanoparticles dispersed in toluene, on particle concentration and temperature. The nanofluid viscosity increases monotonically with particle concentration. We show that although the nanoparticles aggregate to form clusters with increasing concentration, the cluster size is fairly monodisperse and hence the viscosity can be expressed as a function of only the particle concentration. The viscosity of the nanofluid is found to decrease with temperature, similarly to the characteristics of the carrier liquid. We describe these dependencies through an empirical correlation, since the observations are useful to employ such nanofluids in engineering applications.

  7. Study of toluene stability for an Organic Rankine Cycle (ORC) space-based power system

    Science.gov (United States)

    Havens, Vance; Ragaller, Dana

    1988-01-01

    The design, fabrication, assembly, and endurance operation of a dynamic test loop, built to evaluate the thermal stability of a proposed Organic Rankine Cycle (ORC) working fluid, is discussed. The test fluid, toluene, was circulated through a heater, simulated turbine, regenerator, condenser and pump to duplicate an actual ORC system. The maximum nominal fluid temperature, 750 F, was at the turbine simulator inlet. Samples of noncondensible gases and liquid toluene were taken periodically during the test. The samples were analyzed to identify the degradation products formed and the quantity of these products. From these data it was possible to determine the degradation rate of the working fluid and the generation rate of noncondensible gases. A further goal of this work was to relate the degradation observed in the dynamic operating loop to degradation obtained in isothermal capsule tests. This relationship was the basis for estimating the power loop degradation in the Space Station Organic Rankine Cycle system.

  8. 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

  9. Reduced Gasoline Surrogate (Toluene/n-Heptane/iso-Octane) Chemical Kinetic Model for Compression Ignition Simulations

    KAUST Repository

    Sarathy, Mani

    2018-04-03

    Toluene primary reference fuel (TPRF) (mixture of toluene, iso-octane and heptane) is a suitable surrogate to represent a wide spectrum of real fuels with varying octane sensitivity. Investigating different surrogates in engine simulations is a prerequisite to identify the best matching mixture. However, running 3D engine simulations using detailed models is currently impossible and reduction of detailed models is essential. This work presents an AramcoMech reduced kinetic model developed at King Abdullah University of Science and Technology (KAUST) for simulating complex TPRF surrogate blends. A semi-decoupling approach was used together with species and reaction lumping to obtain a reduced kinetic model. The model was widely validated against experimental data including shock tube ignition delay times and premixed laminar flame speeds. Finally, the model was utilized to simulate the combustion of a low reactivity gasoline fuel under partially premixed combustion conditions.

  10. [Effect of ammonium sulfate aerosol on the photochemical reaction of toluene/ NO(x)/air mixture].

    Science.gov (United States)

    Wu, Shan; Hao, Ji-Ming; Lü, Zi-Feng; Zhao, Zhe; Li, Jun-Hua

    2007-06-01

    The effect of ammonium sulfate aerosol on the photochemical reaction of toluene/NO(x)/air mixture was evaluated with Tsinghua Smog Chamber facility. The results indicate that the presence of concentrated preexisting ammonium sulfate aerosol shortens the time to reach maximum PM (particle matter) concentration and increases the aerosol yield of toluene. And under the presence of high concentrated ammonium sulfate aerosol seed, the concentration of aerosol does not have significant effects on NO(x), NO and O3 variation, but affects the formation of secondary organic aerosol (SOA). The SOA yield increases with the increasing initial ammonium sulfate seed concentration (< 160 microg x m(-3)). From the minimum 7.2% to the maximum 11.7%, the percentage increase of SOA yield is more than 60%.

  11. Toluene model for hydrocarbon risk assessment. Final report, 1 January-31 December 1989

    Energy Technology Data Exchange (ETDEWEB)

    Morre, J.

    1990-05-29

    This project was for continuation of research to investigate the molecular mode of action of a membrane-active hydrocarbon, toluene, potentially present in the Air Force environment as a flight fuel component or from other sources and to serve as a model for other membrane-active molecules in the environment. Two important target sites were identified where rapid dose-dependent but reversible changes in the membrane organization occurred at low dose levels. One of these was at the plasma membrane where the ability of the membrane to form protuberances was severely compromised. The other concerned a failure to form protuberances by membranes involved in internal trafficking between the endoplasmic reticulum and the Golgi apparatus. This step was reproduced in a cell-free system making detailed studies possible. The toluene inhibited step was identified as dependent on ATP hydrolysis. The involved ATPase activity was characterized, solubilized and partially purified.

  12. An experimental study of asphaltene particle sizes in n-heptane-toluene mixtures by light scattering

    Directory of Open Access Journals (Sweden)

    Rajagopal K.

    2004-01-01

    Full Text Available The particle size of asphaltene flocculates has been the subject of many recent studies because of its importance in the control of deposition in petroleum production and processing. We measured the size of asphaltene flocculates in toluene and toluene - n-heptane mixtures, using the light-scattering technique. The asphaltenes had been extracted from Brazilian oil from the Campos Basin, according to British Standards Method IP-143/82. The asphaltene concentration in solution ranged between 10-6 g/ml and 10-7 g/ml. Sizes was measured for a period of about 10000 minutes at a constant temperature of 20°C. We found that the average size of the particles remained constant with time and increase with an increase in amount of n-heptane. The correlation obtained for size with concentration will be useful in asphaltene precipitation models.

  13. Lanthanide(III) complexes of aromatic sulfonic acids as catalysts for the nitration of toluene

    Energy Technology Data Exchange (ETDEWEB)

    Parac-Vogt, Tatjana N.; Deleersnyder, Karen; Binnemans, Koen

    2004-07-14

    Ytterbium(III) complexes of benzenesulfonic acid, Yb(BSA){sub 3}, p-toluenesulfonic acid, Yb(Tos){sub 3}, and 2-naphthalenesulfonic acid, Yb(NSA){sub 3}, were prepared and tested as possible catalyst for the nitration of toluene. With a loading of 5-10 mol% of Yb(BSA){sub 3} and Yb(NSA){sub 3}, a quantitative conversion of toluene to nitrotoluene was achieved within 5 h, while Yb(Tos){sub 3} was slightly less active and 77% of nitrated products were obtained. The catalysts can be easily recovered after the reaction, and {sup 1}H NMR spectroscopy of analogous diamagnetic lanthanide(III) catalysts showed that the recovered catalysts were identical to the freshly prepared ones. The ratio of ortho:meta:para products was in all reactions 52:6:42, which is consistent with a direct electrophilic attack by the nitronium ion, NO{sub 2}{sup +}.

  14. Lanthanide(III) complexes of aromatic sulfonic acids as catalysts for the nitration of toluene

    International Nuclear Information System (INIS)

    Parac-Vogt, Tatjana N.; Deleersnyder, Karen; Binnemans, Koen

    2004-01-01

    Ytterbium(III) complexes of benzenesulfonic acid, Yb(BSA) 3 , p-toluenesulfonic acid, Yb(Tos) 3 , and 2-naphthalenesulfonic acid, Yb(NSA) 3 , were prepared and tested as possible catalyst for the nitration of toluene. With a loading of 5-10 mol% of Yb(BSA) 3 and Yb(NSA) 3 , a quantitative conversion of toluene to nitrotoluene was achieved within 5 h, while Yb(Tos) 3 was slightly less active and 77% of nitrated products were obtained. The catalysts can be easily recovered after the reaction, and 1 H NMR spectroscopy of analogous diamagnetic lanthanide(III) catalysts showed that the recovered catalysts were identical to the freshly prepared ones. The ratio of ortho:meta:para products was in all reactions 52:6:42, which is consistent with a direct electrophilic attack by the nitronium ion, NO 2 +

  15. Structural features of HNb3O8 nanosheets and their catalytic performance in toluene nitration

    Science.gov (United States)

    Zhou, Pan; Li, Qingjie; He, Jie; Li, Dewei; Li, Zhong

    2015-11-01

    HNb3O8 nanosheet aggregates ( e-HNb3O8) were prepared by exfoliation and aggregation of layered HNb3O8, which was obtained by protonation of KNb3O8. Especially, in this research, KNb3O8 was synthesized through a novel polymerized complex method (PC) from niobium oxalate. The as-prepared samples were characterized by SEM, HRTEM, XRD, LRS, NH3-TPD, and FT-IR methods. The toluene nitration was used to evaluate the acid catalytic performance of HNb3O8 and e-HNb3O8 samples. The catalytic activity in toluene nitration was related to the structure and acidity of the as-prepared samples. The results show that e-HNb3O8 has a higher specific surface area, stronger acidity and better para-selectivity than the precursor HNb3O8.

  16. Experimental and Simulation Studies of the Toluene on Pure-Silica MEL Zeolite

    DEFF Research Database (Denmark)

    Sanchez-Gil, Vicente; Noya, Eva G.; Sanz, Alejandro

    2016-01-01

    of roughly 4 molecules per unit cell that shifts to higher pressures at higher temperatures and that coincides with a sudden increase in the isosteric heat of adsorption. Grand canonical Monte Carlo simulations reveal that the substep at half load is caused by the adsorption of toluene molecules at different...... of the high load sample. Atomic structural models compatible with the experimental spectra were obtained by performing N-reverse Monte Carlo simulations. Whereas at half load a good fit of the experimental diffraction pattern can be obtained using the rigid zeolite approximation, at high load, this is only......In this work, the adsorption of toluene on pure silica MEL zeolite is investigated using a variety of experimental and simulation methods. First, we measured the volumetric and calorimetric isotherms at 301 K and at 315 K. The volumetric adsorption isotherm presents a substep at a loading...

  17. Biodegradation of Toluene Under Seasonal and Diurnal Fluctuations of Soil-Water Temperature.

    KAUST Repository

    Yadav, Brijesh K

    2012-05-12

    An increasing interest in bioremediation of hydrocarbon polluted sites raises the question of the influence of seasonal and diurnal changes on soil-water temperature on biodegradation of BTEX, a widespread group of (sub)-surface contaminants. Therefore, we investigated the impact of a wide range of varying soil-water temperature on biodegradation of toluene under aerobic conditions. To see the seasonal impact of temperature, three sets of batch experiments were conducted at three different constant temperatures: 10°C, 21°C, and 30°C. These conditions were considered to represent (1) winter, (2) spring and/or autumn, and (3) summer seasons, respectively, at many polluted sites. Three additional sets of batch experiments were performed under fluctuating soil-water temperature cases (21<>10°C, 30<>21°C, and 10<>30°C) to mimic the day-night temperature patterns expected during the year. The batches were put at two different temperatures alternatively to represent the day (high-temperature) and night (low-temperature) times. The results of constant- and fluctuating-temperature experiments show that toluene degradation is strongly dependent on soil-water temperature level. An almost two-fold increase in toluene degradation time was observed for every 10°C decrease in temperature for constant-temperature cases. Under fluctuating-temperature conditions, toluene degraders were able to overcome the temperature stress and continued thriving during all considered weather scenarios. However, a slightly longer time was taken compared to the corresponding time at daily mean temperature conditions. The findings of this study are directly useful for bioremediation of hydrocarbon-polluted sites having significant diurnal and seasonal variations of soil-water temperature.

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

    International Nuclear Information System (INIS)

    Gonzalez Vanderhaghen, D.E.

    1998-01-01

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

  19. Monte Carlo calculation of the total probability for gamma-Ray interaction in toluene

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Garcia-Torano, E.

    1983-01-01

    Interaction and absorption probabilities for gamma-rays with energies between 1 and 1000 KeV have been computed and tabulated. Toluene based scintillator solution has been assumed in the computation. Both, point sources and homogeneously dispersed radioactive material have been assumed. These tables may be applied to cylinders with radii between 1.25 cm and 0.25 cm and heights between 4.07 cm and 0.20 cm. (Author) 26 refs

  20. Self-diffusion in benzene-toluene and benzene-cyclohexane solutions

    International Nuclear Information System (INIS)

    Reimschuessel, W.; Hawlicka, E.

    1977-01-01

    The self-diffusion in benzene-toluene and benzene-cyclohexane solutions have been measured at different temperatures. The capillary-cell method was employed. The activation parameters of self-diffusion for the systems are presented. The data have been used to test the validity of various diffusion equations proposed in the literature. The hypothesis that the self-diffusion was realized by movement of aggregates of molecules is suggested. (orig.) [de

  1. Extraction of lanthanoid(3) nitrates of cerium group by trialkylbenzylammonium nitrate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kovalev, S.V.; Keskinov, V.A.

    1997-01-01

    Extraction of lanthanoid(3) nitrates of cerium group by trialkylbenzylammonium in toluene at T=298.15 K and pH 2 is studied. The extraction isotherms are described with an account of formation of compounds (R 4 N) i [Ln(NO 3 ) 3+i ] [i=2, 3 for Pr, Nd, Sm, Eu, Gd(3) and i=3, 4 for La, Ce(3)] in organic form. The extraction constants values are calculated

  2. Synthesis of mesoporous BiOBr 3D microspheres and their photodecomposition for toluene

    International Nuclear Information System (INIS)

    Feng Yinchang; Li Lei; Li Junwei; Wang Junfeng; Liu Lu

    2011-01-01

    Graphical abstract: Display Omitted Highlights: → Mesoporous bismuth oxybromide (BiOBr) microspheres assembled by nanosheets were synthesized by a simple solvothermal route. → It was reported for the first time that mesoporous BiOBr microspheres were used to degrade gas phase toluene. → The intermediates under different irradiation source were identified and the relationship between intermediates and reaction rate constant was discussed. → Fifteen kinds of intermediates were detected through GC-MS analysis, and a tentative degradation pathway was proposed. - Abstract: In this article, a facile solvothermal method was introduced to synthesize mesoporous BiOBr microspheres with Bi(NO 3 ) 3 as Bi source. The synthesized catalysts were characterized by XRD, SEM, TEM, XPS, UV-vis, TG-DTA, and N 2 -adsorption-desorption, and their photoactivity was evaluated by gaseous toluene both under UV and UV-vis irradiation with Degussa TiO 2 P 25 as reference. The prepared BiOBr catalysts were of pure tetragonal phase and its band gap energy was calculated to be about 2.64 eV. Comparing with P 25 , BiOBr showed promoted photocatalytic activity under UV-vis irradiation, during which more than 90% of toluene was eliminated after 5 h irradiation. Kinetic analysis further demonstrated the enhanced activity of BiOBr under UV-vis irradiation and the reaction rate constant k of BiOBr was nearly 2 times higher than that of P 25 . The superior activity of BiOBr under UV-vis irradiation can be attributed to its hierarchical structure and suitable band gap energy. Moreover, the reacted intermediates under different light source were identified by GC-MS. Fifteen main intermediates were identified and a tentative pathway of toluene degradation by BiOBr was proposed.

  3. Characterization and performance of a toluene-degrading biofilm developed on pumice stones

    OpenAIRE

    Di Lorenzo, Alessandra; Varcamonti, Mario; Parascandola, Palma; Vignola, Rodolfo; Bernardi, Adriano; Sacceddu, Pasquale; Sisto, Raffaello; de Alteriis, Elisabetta

    2005-01-01

    Abstract Background Hydrocarbon-degrading biofilms in the treatment of contaminated groundwaters have received increasing attention due to the role played in the so-called "biobarriers". These are bioremediation systems in which a microbial consortium adherent to a solid support is placed across the flow of a contaminated plume, thus promoting biodegradation of the pollutant. Results A microbial consortium adherent to pumice granules (biofilm) developed from a toluene-enriched microflora in a...

  4. Start-up and Performance Characteristics of a Trickle Bed Reaktor Degrading Toluene

    Czech Academy of Sciences Publication Activity Database

    Misiaczek, O.; Paca, J.; Halecký, M.; Gerrard, A. M.; Sobotka, Miroslav; Soccol, C. R.

    2007-01-01

    Roč. 50, č. 5 (2007), s. 871-877 ISSN 1516-8913 Grant - others:GA ČR(CZ) GA104/05/0194 Institutional research plan: CEZ:AV0Z50200510 Source of funding: V - iné verejné zdroje Keywords : biotrickling filter * constructed mixed population * toluene Subject RIV: EE - Microbiology, Virology Impact factor: 0.349, year: 2007

  5. Cu and Boron Doped Carbon Nitride for Highly Selective Oxidation of Toluene to Benzaldehyde

    Directory of Open Access Journals (Sweden)

    Hongling Han

    2015-07-01

    Full Text Available A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB was synthesized using cheap precursors and systematically characterized. The selective oxidation of toluene proceeded very smoothly over the catalyst at 70 °C using tert-butyl hydroperoxide (TBHP as the oxidant to exclusively afford benzaldehyde. The catalyst can be used for at least five cycles without decrease in activity and selectivity.

  6. Molecular Diffusion of Toluene through CaCO3-Filled Natural Rubber Composites

    Directory of Open Access Journals (Sweden)

    Hedayatollah Sadeghi Ghari

    2012-12-01

    Full Text Available The transport properties of liquids and gases through polymeric materialsplay a very important role in some areas of industrial applications. In thisstudy, natural rubber (NR/CaCO3 composites were prepared by melt mixingmethod. By equilibrium swelling test, the transport process of toluene in the prepared natural rubber composites was investigated. The diffusion and transport of toluene through calcium carbonate-filled natural rubber composites have been studied in the temperature range 25–45°C. The diffusion of toluene through these composites was studied with special reference to the effect of filler concentration and temperature.The transport coefficients such as diffusion, permeation and sorption coefficients were estimated from the swelling data. To find out the mechanism of diffusion in prepared composites, the results of swelling studies were applied to an empirical equation. In these composites, diffusion is approximately based on Fickian diffusion mechanism and by increases in temperature; diffusion mechanism is more close to Fickian mechanism. Increase of filler content in composite would result in decreased ultimateswelling and slower diffusion rate of solvent. The diffusion rate, diffusion coefficient and the permeability increased by temperature. The study of the diffusion of toluene through filled natural rubber indicated that the concentration of filler plays an important role in the diffusion, sorption and permeation coefficients. Also interfacial interactions in NR composites were checked by dynamic-mechanical analysis. The microstructure and dispersion of calcium carbonate particles in natural rubber matrix were studiedby field emission scanning electron microscopy (FE-SEM. In general, the results of swelling tests, dynamic-mechanical analysis and FE-SEM images show that the optimized value of filler in NR composites is equal to 10 phr calcium carbonate.

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

    International Nuclear Information System (INIS)

    Azzouz, A.; Fourar, M.; Berrak, A.

    1984-06-01

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

  8. Extraction of U(VI) with unsymmetrical N-methyl-N-octyl alkylamides in toluene

    International Nuclear Information System (INIS)

    Sun Guoxin; Li Yexin; Zhang Zhenwei; Cui Yu; Shandong University, Jinan; Sun Sixiu

    2005-01-01

    Extraction of U(VI) with three new unsymmetrical monoamides, N-methyl-N-octyloctylamide (MOOA), N-methyl-N-octyldecanamide (MODA), and N-methyl-N-octyldodecanamide (MODOA), from nitric acid solution employing toluene as diluent is discussed. The effects of nitric acid, sodium nitrate and extractant concentrations and also the temperature on the distribution ratio have been investigated. The extracted species were studied by IR spectrometry. (author)

  9. Evaluation of Toluene Exposure in Workers at Industrial Area of Sidoarjo, Indonesia by Measurement of Urinary Hippuric Acid

    Directory of Open Access Journals (Sweden)

    Moch Sahri

    2013-12-01

    How to cite this article: Sahri M, Widajati N. Evaluation of Toluene Exposure in Workers at Industrial Area of Sidoarjo, Indonesia by Measurement of Urinary Hippuric Acid. Asia Pac J Med Toxicol 2013;2:145-9.

  10. Toluene effects on oxidative stress in brain regions of young-adult, middle-age, and senescent Brown Norway rats

    Energy Technology Data Exchange (ETDEWEB)

    Kodavanti, Prasada Rao S., E-mail: kodavanti.prasada@epa.gov [Neurotoxicology Branch, Toxicity Assessment Division, NHEERL, ORD, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Royland, Joyce E. [Genetic and Cellular Toxicology Branch, Integrated Systems Toxicology Division, NHEERL, ORD, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Richards, Judy E. [Research Core Unit, NHEERL, ORD, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Besas, Jonathan; MacPhail, Robert C. [Neurotoxicology Branch, Toxicity Assessment Division, NHEERL, ORD, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States)

    2011-11-15

    The influence of aging on susceptibility to environmental contaminants is not well understood. To extend knowledge in this area, we examined effects in rat brain of the volatile organic compound, toluene. The objective was to test whether oxidative stress (OS) plays a role in the adverse effects caused by toluene exposure, and if so, if effects are age-dependent. OS parameters were selected to measure the production of reactive oxygen species (NADPH Quinone oxidoreductase 1 (NQO1), NADH Ubiquinone reductase (UBIQ-RD)), antioxidant homeostasis (total antioxidant substances (TAS), superoxide dismutase (SOD), {gamma}-glutamylcysteine synthetase ({gamma}-GCS), glutathione transferase (GST), glutathione peroxidase (GPX), glutathione reductase (GRD)), and oxidative damage (total aconitase and protein carbonyls). In this study, Brown Norway rats (4, 12, and 24 months) were dosed orally with toluene (0, 0.65 or 1 g/kg) in corn oil. Four hours later, frontal cortex, cerebellum, striatum, and hippocampus were dissected, quick frozen on dry ice, and stored at - 80 Degree-Sign C until analysis. Some parameters of OS were found to increase with age in select brain regions. Toluene exposure also resulted in increased OS in select brain regions. For example, an increase in NQO1 activity was seen in frontal cortex and cerebellum of 4 and 12 month old rats following toluene exposure, but only in the hippocampus of 24 month old rats. Similarly, age and toluene effects on glutathione enzymes were varied and brain-region specific. Markers of oxidative damage reflected changes in oxidative stress. Total aconitase activity was increased by toluene in frontal cortex and cerebellum at 12 and 24 months, respectively. Protein carbonyls in both brain regions and in all age groups were increased by toluene, but step-down analyses indicated toluene effects were statistically significant only in 12 month old rats. These results indicate changes in OS parameters with age and toluene exposure

  11. Size-restricted proton transfer within toluene-methanol cluster ions.

    Science.gov (United States)

    Chiang, Chi-Tung; Shores, Kevin S; Freindorf, Marek; Furlani, Thomas; DeLeon, Robert L; Garvey, James F

    2008-11-20

    To understand the interaction between toluene and methanol, the chemical reactivity of [(C6H5CH3)(CH3OH) n=1-7](+) cluster ions has been investigated via tandem quadrupole mass spectrometry and through calculations. Collision Induced Dissociation (CID) experiments show that the dissociated intracluster proton transfer reaction from the toluene cation to methanol clusters, forming protonated methanol clusters, only occurs for n = 2-4. For n = 5-7, CID spectra reveal that these larger clusters have to sequentially lose methanol monomers until they reach n = 4 to initiate the deprotonation of the toluene cation. Metastable decay data indicate that for n = 3 and n = 4 (CH3OH)3H(+) is the preferred fragment ion. The calculational results reveal that both the gross proton affinity of the methanol subcluster and the structure of the cluster itself play an important role in driving this proton transfer reaction. When n = 3, the cooperative effect of the methanols in the subcluster provides the most important contribution to allow the intracluster proton transfer reaction to occur with little or no energy barrier. As n >or= 4, the methanol subcluster is able to form ring structures to stabilize the cluster structures so that direct proton transfer is not a favored process. The preferred reaction product, the (CH3OH)3H(+) cluster ion, indicates that this size-restricted reaction is driven by both the proton affinity and the enhanced stability of the resulting product.

  12. Probing the proteome response to toluene exposure in the solvent tolerant Pseudomonas putida S12.

    Science.gov (United States)

    Wijte, Dorien; van Baar, Ben L M; Heck, Albert J R; Altelaar, A F Maarten

    2011-02-04

    To enhance target production from biocatalysts, it is necessary to thoroughly understand the molecular mechanisms involved in production, degradation, and, importantly, adaptation to the required environment. One such bacterium with high potential for biocatalysis is the solvent-tolerant bacteria Pseudomonas putida S12, which, among others, is able to degrade organic solvents. For bioconversion of organic solvents to become a successful industrial process, the understanding of the molecular response upon solvent tolerance is essential. Here we performed a quantitative analysis of the P. putida S12 proteome at different stages of adaptation to toluene. Using a stable isotope dimethylation labeling approach we monitored the differential expression of 528 proteins, including often hard-to-detect membrane associate proteins, such as multiple RND-family transporters and ABC transporters of nutrients. Our quantitative proteomics approach revealed the remarkable ability of P. putida S12 to severely change its protein expression profile upon toluene exposure. This proteome response entails a significant increase in energy metabolism and expression of the solvent efflux pump SrpABC, confirming its role in solvent tolerance. Other proteins strongly up-regulated in the presence of toluene include the multidrug efflux membrane protein PP1272 and the cation/acetate symporter ActP and may form interesting alternative targets for improving solvent tolerance.

  13. A novel integrated thermally coupled moving bed reactors for naphtha reforming process with hydrodealkylation of toluene

    International Nuclear Information System (INIS)

    Iranshahi, Davood; Saeedi, Reza; Azizi, Kolsoom; Nategh, Mahshid

    2017-01-01

    Highlights: • A novel thermally coupled reactor in CCR naphtha reforming process is modeled. • The required heat of Naphtha process is attained with toluene hydrodealkylation. • A new kinetic model involving 32 pseudo-component and 84 reactions is proposed. • The aromatics and hydrogen production increase 19% and 23%, respectively. - Abstract: Due to the importance of catalytic naphtha reforming process in refineries, development of this process to attain the highest yield of desired products is crucial. In this study, continuous catalyst regeneration naphtha reforming process with radial flow is coupled with hydrodealkylation of toluene to prevent energy loss while enhancing aromatics and hydrogen yields. In this coupled process, heat is transferred between hot and cold sections (from hydrodealkylation of toluene to catalytic naphtha reforming process) using the process integration method. A steady-state two-dimensional model, which considers coke formation on the catalyst pellets, is developed and 32 pseudo-components with 84 reactions are investigated. Kinetic model utilized for HDA process is homogeneous and non-catalytic. The modeling results reveal an approximate increase of 19% and 23% in aromatics and hydrogen molar flow rates, respectively, in comparison with conventional naphtha reforming process. The improvement in aromatics production evidently indicates that HDA is a suitable process to be coupled with naphtha reforming.

  14. Low energy electron and O- reactions in films of O2 coadsorbed with benzene or toluene.

    Science.gov (United States)

    Imhoff, Marjorie; Parenteau, Luc; Sanche, Leon; Huels, Michael A

    2005-09-21

    A detailed understanding of nascent reactive events leading to DNA damage is required to describe ionizing radiation effects on living cells. These early, sub-picosecond events involve mainly low energy (E benzene (C6H6), or toluene (C6H5CH3); these molecules represent the most fundamental structural analogs of pyrimidine bases. Our experiments show that all of the observed OH- yields are the result of reactive scattering of 1-5 eV O- fragments produced initially by DEA to O2. These O- reactions involve hydrogen abstraction from benzene or toluene, and result in the formation of benzyl radicals, or toluene radicals centered on either the ring or exocyclic methyl group. O- scatters over nm distances comparable to DNA dimensions, and reactions involve a transient anion collision complex. Anion desorption is found to depend on both, the temperature of hydrocarbon film formation (morphology), and the order of overlayer adsorption, e.g. O2 on benzene, or benzene on O2. Our measurements support the notion that in irradiated DNA similar secondary-ion reactions can be initiated by the abundant secondary electrons, and may lead to clustered damage.

  15. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

    Directory of Open Access Journals (Sweden)

    Debarpita Ghosal

    2015-07-01

    Full Text Available The performance of toluene methylation reaction was studied on H-ZSM-5 catalyst modified with La, Ce and Nb at different percentage loading. It was found that 10% metal loading produced the best performance in the reaction in terms of toluene conversion. The catalyst was coated on silicon carbide foam support which showed better conversion than the pelleted catalyst. Again, among the treated and untreated H-ZSM-5, the La-ZSM-5 catalyst is chosen for the reaction for its highest selectivity towards xylene, the main product. All catalysts were characterized in terms of surface properties, SEM, XRD and NH3-TPD. Kinetic study was done on La-ZSM-5 catalyst with 10% loading. In this kineticstudy, Langmuir Hinshelwood kinetic model with surface reaction as rate controlling step was selected as the rate equation. The activation energy was found to be 47 kJ/mol. © 2015 BCREC UNDIP. All rights reserved. Received: 9th December 2014; Revised: 27th April 2015; Accepted: 29th April 2015  How to Cite: Ghosal, D., Basu, J.K., Sengupta, S. (2015. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 201-209. (doi:10.9767/bcrec.10.2.7872.201-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7872.201-209  

  16. Hydropyrolysis of n-Hexane and Toluene to Acetylene in Rotating-Arc Plasma

    Directory of Open Access Journals (Sweden)

    Jie Ma

    2017-07-01

    Full Text Available Thermal plasma pyrolysis is a powerful technology for converting waste or low-value materials to valuable gaseous hydrocarbons. This paper presents for the first time the hydropyrolysis of n-hexane and toluene in a rotating-arc plasma reactor. Effects of the mole ratio of H/C in the feed, power input and magnetic induction were investigated to evaluate the reaction performance. A lower H/C ratio could lead to a lower yield of C2H2 and lower specific energy consumption, and there existed an optimum range of power input for both n-hexane and toluene pyrolysis within the investigated range. The yield of C2H2 in n-hexane and toluene pyrolysis could reach 85% and 68%, respectively, with respective specific energy consumption (SEC of 13.8 kWh/kg·C2H2 and 19.9 kWh/kg·C2H2. Compared with the results reported in literature, the rotating-arc plasma process showed higher C2H2 yield and lower energy consumption, which is attributed to the better initial mixing of the reactant with the hot plasma gas and the more uniform temperature distribution.

  17. Heterogeneous Reactions between Toluene and NO2 on Mineral Particles under Simulated Atmospheric Conditions.

    Science.gov (United States)

    Niu, Hejingying; Li, Kezhi; Chu, Biwu; Su, Wenkang; Li, Junhua

    2017-09-05

    Heterogeneous reactions between organic and inorganic gases with aerosols are important for the study of smog occurrence and development. In this study, heterogeneous reactions between toluene and NO 2 with three atmospheric mineral particles in the presence or absence of UV light were investigated. The three mineral particles were SiO 2 , α-Fe 2 O 3 , and BS (butlerite and szmolnokite). In a dark environment, benzaldehyde was produced on α-Fe 2 O 3 . For BS, nitrotoluene and benzaldehyde were obtained. No aromatic products were produced in the absence of NO 2 in the system. In the presence of UV irradiation, benzaldehyde was detected on the SiO 2 surface. Identical products were produced in the presence and absence of UV light over α-Fe 2 O 3 and BS. UV light promoted nitrite to nitrate on mineral particles surface. On the basisi of the X-ray photoelectron spectroscopy (XPS) results, a portion of BS was reduced from Fe 3+ to Fe 2+ with the adsorption of toluene or the reaction with toluene and NO 2 . Sulfate may play a key role in the generation of nitrotoluene on BS particles. From this research, the heterogeneous reactions between organic and inorganic gases with aerosols that occur during smog events will be better understood.

  18. Determination of reactor operation for the microbial hydroxylation of toluene in a two-liquid phase process

    DEFF Research Database (Denmark)

    Collins, AM; Woodley, John; Liddell, JM

    1995-01-01

    to toluene cis-glycol by Pseudomonas putida UV4. Toxic effects may be eliminated through the introduction of tetradecane, to partition toluene away from the biocatalyst, to give product concentrations of 30-60 g L(-1), in a two-liquid-phase reactor. The operational limits of this system have been...... experimentally determined and are presented in the form of windows of operation....

  19. Experimental and predicted volumetric and refractive index properties of ternary mixtures of iodoethane with toluene and alcohols at temperature 298.15K and pressure 101kPa

    International Nuclear Information System (INIS)

    Atik, Zadjia

    2006-01-01

    Excess molar volumes V m E and change in refractive indices Δ mix n of the binary mixtures of (toluene+methanol) (toluene+ethanol) (toluene+1-propanol) (toluene+iodoethane) (methanol+iodoethane) (ethanol+iodoethane) (1-propanol+iodoethane), and the ternary mixtures of (toluene+methanol+iodoethane) (toluene+ethanol+iodoethane), and (toluene+1-propanol+iodoethane) were measured with vibrating-tube densimeters and an Abbe-type refractometer at the temperature 298.15K and the pressure 101kPa. The experimental V m E and Δ mix n values of the ternary systems were predicted by empirical equations using binary solution data

  20. Adsorptive Removal of Benzene and Toluene from Aqueous Environments by Cupric Oxide Nanoparticles: Kinetics and Isotherm Studies

    Directory of Open Access Journals (Sweden)

    Leili Mohammadi

    2017-01-01

    Full Text Available Removal of benzene and toluene, as the major pollutants of water resources, has attracted researchers’ attention, given the risk they pose to human health. In the present study, the potential of copper oxide nanoparticles (CuO-NPs in eliminating benzene and toluene from a mixed aqueous solution was evaluated. For this, we performed batch experiments to investigate the effect of solution pH (3–13, dose of CuO-NPs (0.1–0.8 g, contact time (5–120 min, and concentration of benzene and toluene (10–200 mg/l on sorption efficiency. The maximum removal was observed at neutral pH. By using the Langmuir model, we measured the highest adsorption capacity to be 100.24 mg/g for benzene and 111.31 mg/g for toluene. Under optimal conditions, adsorption efficiency was 98.7% and 92.5% for benzene and toluene, respectively. The sorption data by CuO-NPs well fitted into the following models: Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich model. The experimental information well fitted in the Freundlich for benzene and Langmuir for toluene. Based on the results, adsorption followed pseudo-second-order kinetics with acceptable coefficients. The findings introduced CuO-NPs as efficient compounds in pollutants adsorption. In fact, they could be used to develop a simple and efficient pollutant removal method from aqueous solutions.

  1. Effect of Silica Alumina Ratio and Thermal Treatment of Beta Zeolites on the Adsorption of Toluene from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Elena Sarti

    2017-02-01

    Full Text Available The adsorption of toluene from aqueous solutions onto hydrophobic zeolites was studied by combining chromatographic, thermal and structural techniques. Three beta zeolites (notated BEAs, since they belong to BEA framework type, with different SiO2/Al2O3 ratios (i.e., 25, 38 and 360, before and after calcination, were tested as adsorbents of toluene from aqueous media. This was performed by measuring the adsorbed quantities of toluene onto zeolites in a wide concentration range of solute. The adsorption data were fitted with isotherms whose models are based on surface heterogeneity of the adsorbent, according to the defective structure of beta zeolites. The thermal treatment considerably increases the adsorption of toluene, in the low concentration range, on all BEAs, probably due to surface and structural modifications induced by calcination. Among the calcined BEAs, the most hydrophobic zeolite (i.e., that with SiO2/Al2O3 ratio of 360 showed the highest binding constant, probably due to its high affinity for an organophilic solute such as toluene. The high sorption capacity was confirmed by thermogravimetric analyses on BEAs, before and after saturation with toluene.

  2. Toluene combustion: reaction paths, thermochemical properties, and kinetic analysis for the methylphenyl radical + O2 reaction.

    Science.gov (United States)

    da Silva, Gabriel; Chen, Chiung-Chu; Bozzelli, Joseph W

    2007-09-06

    Aromatic compounds such as toluene and xylene are major components of many fuels. Accurate kinetic mechanisms for the combustion of toluene are, however, incomplete, as they do not accurately model experimental results such as strain rates and ignition times and consistently underpredict conversion. Current kinetic mechanisms for toluene combustion neglect the reactions of the methylphenyl radicals, and we believe that this is responsible, in part, for the shortcomings of these models. We also demonstrate how methylphenyl radical formation is important in the combustion and pyrolysis of other alkyl-substituted aromatic compounds such as xylene and trimethylbenzene. We have studied the oxidation reactions of the methylphenyl radicals with O2 using computational ab initio and density functional theory methods. A detailed reaction submechanism is presented for the 2-methylphenyl radical + O2 system, with 16 intermediates and products. For each species, enthalpies of formation are calculated using the computational methods G3 and G3B3, with isodesmic work reactions used to minimize computational errors. Transition states are calculated at the G3B3 level, yielding high-pressure limit elementary rate constants as a function of temperature. For the barrierless methylphenyl + O2 and methylphenoxy + O association reactions, rate constants are determined from variational transition state theory. Multichannel, multifrequency quantum Rice-Ramsperger-Kassel (qRRK) theory, with master equation analysis for falloff, provides rate constants as a function of temperature and pressure from 800 to 2400 K and 1 x 10(-4) to 1 x 10(3) atm. Analysis of our results shows that the dominant pathways for reaction of the three isomeric methylphenyl radicals is formation of methyloxepinoxy radicals and subsequent ring opening to methyl-dioxo-hexadienyl radicals. The next most important reaction pathway involves formation of methylphenoxy radicals + O in a chain branching process. At lower

  3. Wavelength and NOx dependent complex refractive index of SOAs generated from the photooxidation of toluene

    Science.gov (United States)

    Nakayama, T.; Sato, K.; Matsumi, Y.; Imamura, T.; Yamazaki, A.; Uchiyama, A.

    2013-01-01

    Recently, secondary organic aerosols (SOAs) generated from anthropogenic volatile organic compounds have been proposed as a possible source of light-absorbing organic compounds, "brown carbon," in the urban atmosphere. However, the atmospheric importance of these SOAs remains unclear due to limited information about their optical properties. In this study, the complex refractive index (RI, m = n-ki values at 405, 532, and 781 nm of the SOAs generated during the photooxidation of toluene (toluene-SOAs) under a variety of initial nitrogen oxide (NOx = NO + NO2) conditions were examined by photoacoustic spectroscopy (PAS) and cavity ring-down spectroscopy (CRDS). The complex RI-values obtained in the present study and reported in the literature indicate that the k-value, which represents the light absorption of the toluene-SOAs, increased to shorter wavelengths at nitrate to organics ratio of the SOAs determined using a high-resolution time-of-flight aerosol mass spectrometer (H-ToF-AMS) also increased with increasing initial NOx concentration. The RI-values of the SOAs generated during the photooxidation of 1,3,5-trimethylbenzene in the presence of NOx (1,3,5-TMB-SOAs) were also determined to investigate the influence of the chemical structure of the precursor on the optical properties of the SOAs, and it was found that the light absorption of the 1,3,5-TMB-SOAs is negligible at all of the wavelengths investigated (405, 532, and 781 nm). These results can be reasonably explained by the hypothesis that nitroaromatic compounds, such as nitrocresols, are the major contributors to the light absorption of the toluene-SOAs. Using the obtained RI-values, mass absorption cross sections of the toluene-SOAs at 405 nm were estimated to be 0.08-0.52 m2g-1 under typical conditions in an urban atmosphere during the daytime. These results indicate that light absorption by the SOAs potentially contributes to the radiation balance at ultraviolet wavelengths below ~400 nm

  4. CYP2E1 epigenetic regulation in chronic, low-level toluene exposure: Relationship with oxidative stress and smoking habit

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez-Garza, Octavio, E-mail: ojimenezgarza@ugto.mx [Health Sciences Division, University of Guanajuato Campus León, Blvd. Puente del Milenio 1001, Fracción del Predio San Carlos, C.P. 37670 León, Guanajuato (Mexico); Baccarelli, Andrea A.; Byun, Hyang-Min [Laboratory of Environmental Epigenetics, Department of Environmental Health, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115 (United States); Márquez-Gamiño, Sergio [Health Sciences Division, University of Guanajuato Campus León, Blvd. Puente del Milenio 1001, Fracción del Predio San Carlos, C.P. 37670 León, Guanajuato (Mexico); Barrón-Vivanco, Briscia Socorro [Environmental Toxicology and Pollution Laboratory, Nayarit Autonomous University, Av. Ciudad de la Cultura s/n, “Amado Nervo”, Tepic, Nayarit C.P. 63155 (Mexico); Albores, Arnulfo [Department of Toxicology, CINVESTAV, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360 Mexico DF (Mexico)

    2015-08-01

    Background: CYP2E1 is a versatile phase I drug-metabolizing enzyme responsible for the biotransformation of most volatile organic compounds, including toluene. Human toluene exposure increases CYP2E1 mRNA and modifies its activity in leucocytes; however, epigenetic implications of this interaction have not been investigated. Goal: To determine promoter methylation of CYP2E1 and other genes known to be affected by toluene exposure. Methods: We obtained venous blood from 24 tannery workers exposed to toluene (mean levels: 10.86 +/− 7 mg/m{sup 3}) and 24 administrative workers (reference group, mean levels 0.21 +/− 0.02 mg/m{sup 3}) all of them from the city of León, Guanajuato, México. After DNA extraction and bisulfite treatment, we performed PCR-pyrosequencing in order to measure methylation levels at promoter region of 13 genes. Results: In exposed group we found significant correlations between toluene airborne levels and CYP2E1 promoter methylation (r = − .36, p < 0.05), as well as for IL6 promoter methylation levels (r = .44, p < 0.05). Moreover, CYP2E1 promoter methylation levels where higher in toluene-exposed smokers compared to nonsmokers (p = 0.009). We also observed significant correlations for CYP2E1 promoter methylation with GSTP1 and SOD1 promoter methylation levels (r = − .37, p < 0.05 and r = − .34, p < 0.05 respectively). Conclusion: These results highlight the importance of considering CYP2E1 epigenetic modifications, as well as its interactions with other genes, as key factors for unraveling the sub cellular mechanisms of toxicity exerted by oxidative stress, which can initiate disease process in chronic, low-level toluene exposure. People co-exposed to toluene and tobacco smoke are in higher risk due to a possible CYP2E1 repression. - Highlights: • We investigated gene-specific methylation in persons chronically exposed to toluene. • In a previous study, a reduced CYP2E1 activity was observed in these participants. • CYP2E1

  5. Indoor exposure to toluene from printed matter matters: complementary views from life cycle assessment and risk assessment.

    Science.gov (United States)

    Walser, Tobias; Juraske, Ronnie; Demou, Evangelia; Hellweg, Stefanie

    2014-01-01

    A pronounced presence of toluene from rotogravure printed matter has been frequently observed indoors. However, its consequences to human health in the life cycle of magazines are poorly known. Therefore, we quantified human-health risks in indoor environments with Risk Assessment (RA) and impacts relative to the total impact of toxic releases occurring in the life cycle of a magazine with Life Cycle Assessment (LCA). We used a one-box indoor model to estimate toluene concentrations in printing facilities, newsstands, and residences in a best, average, and worst-case scenario. The modeled concentrations are in the range of the values measured in on-site campaigns. Toluene concentrations can be close or even surpass the occupational legal thresholds in printing facilities in realistic worst-case scenarios. The concentrations in homes can surpass the US EPA reference dose (69 μg/kg/day) in worst-case scenarios, but are still at least 1 order of magnitude lower than in press rooms or newsstands. However, toluene inhaled at home becomes the dominant contribution to the total potential human toxicity impacts of toluene from printed matter when assessed with LCA, using the USEtox method complemented with indoor characterization factors for toluene. The significant contribution (44%) of toluene exposure in production, retail, and use in households, to the total life cycle impact of a magazine in the category of human toxicity, demonstrates that the indoor compartment requires particular attention in LCA. While RA works with threshold levels, LCA assumes that every toxic emission causes an incremental change to the total impact. Here, the combination of the two paradigms provides valuable information on the life cycle stages of printed matter.

  6. Contributions of toluene and alpha-pinene to SOA formed in an irradiated toluene/alpha-pinene/NO(x)/ air mixture: comparison of results using 14C content and SOA organic tracer methods.

    Science.gov (United States)

    Offenberg, John H; Lewis, Charles W; Lewandowski, Michael; Jaoui, Mohammed; Kleindienst, Tadeusz E; Edney, Edward O

    2007-06-01

    An organic tracer method, recently proposed for estimating individual contributions of toluene and alpha-pinene to secondary organic aerosol (SOA) formation, was evaluated by conducting a laboratory study where a binary hydrocarbon mixture, containing the anthropogenic aromatic hydrocarbon, toluene, and the biogenic monoterpene, alpha-pinene, was irradiated in air in the presence of NO(x) to form SOA. The contributions of toluene and alpha-pinene to the total SOA concentration, calculated using the organic tracer method, were compared with those obtained with a more direct 14C content method. In the study, SOA to SOC ratios of 2.07 +/- 0.08 and 1.41 +/- 0.04 were measured for toluene and (alpha-pinene SOA, respectively. The individual tracer-based SOA contributions of 156 microg m(-3) for toluene and 198 microg m(-)3 for alpha-pinene, which together accounted for 82% of the gravimetrically determined total SOA concentration, compared well with the 14C values of 182 and 230 microg m(-3) measured for the respective SOA precursors. While there are uncertainties associated with the organic tracer method, largely due to the chemical complexity of SOA forming chemical mechanisms, the results of this study suggest the organic tracer method may serve as a useful tool for determining whether a precursor hydrocarbon is a major SOA contributor.

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

    Science.gov (United States)

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

    2010-02-04

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

  8. Nitration of toluene 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)

    1999-06-30

    In order to clarify the mechanism of aromatic nitration with N[sub 2]O[sub 5], the nitration of toluene with N[sub 2]O[sub 5] in CCl[sub 4] was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N[sub 2]O[sub 5] powder without CCl[sub 4] was also carried out. The nitration of toluene with N[sub 2]O[sub 5]/N[sub 2]O[sub 4] was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N[sub 2]O[sub 5] was showed. As a result, it is suggested that N[sub 2]O[sub 5] should be dissociated homolytically in CCl[sub 4] and that the aromatic nitration with N[sub 2]O[sub 5] in CCl[sub 4] should proceed with NO[sub 3] as the initial attacking species. The thermal decomposition of 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 specific isomer distributions. (author)

  9. Nitration of toluene 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

    1999-06-30

    In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitration of toluene with N{sub 2}O{sub 5} in CCl{sub 4} was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N{sub 2}O{sub 5} powder without CCl{sub 4} was also carried out. The nitration of toluene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N{sub 2}O{sub 5} was showed. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4} and that the aromatic nitration with N{sub 2}O{sub 5} in CCl{sub 4} should proceed with NO{sub 3} as the initial attacking species. The thermal decomposition of 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 specific isomer distributions. (author)

  10. Developmental and reproductive toxicity evaluation of toluene vapor in the rat II. Developmental toxicity.

    Science.gov (United States)

    Roberts, L G; Nicolich, M J; Schreiner, C A

    2007-06-01

    The developmental toxicity of toluene was evaluated via whole body inhalation exposure, in pregnant Sprague Dawley rats exposed to toluene (99.9% pure) from gestation day (GD) 6-15 inclusive, 6h/day, at concentrations of 0, 250, 750, 1500 and 3000ppm (0, 938, 2812, 5625 and 11250mg/m(3)). Doses were selected from a preliminary study performed over a range of concentrations from 0 to 5000ppm, in which maternal and fetal toxicity were observed at 2000ppm and above. This study has been cited in various regulatory documents and is presented here to allow greater accessibility to results and conclusions. Toluene induced clinical signs in pregnant dams (ataxia, hyper-responsivity, increased water intake, decreased food consumption) at 3000ppm, ataxia and hyper-responsivity at 1500ppm, and reduced maternal body weight gain at 1500 during the exposure period only and at 3000ppm from initiation of exposure to GD20. At Caesarean section on GD20, no adverse effects on implantation, number and viability of fetuses, or fetal sex distribution were observed. Litter weight and mean fetal weight was reduced at 3000ppm and mean fetal weight was reduced at 1500ppm. Instances of reduced or unossified skeletal elements occurred at the same dose levels. Mean fetal weight was also reduced at 250ppm but not at 750ppm. Extensive statistical analysis of fetal body weight data support the conclusion that there is no toxicologically significant dose-related effect on fetal body weight at or below 750ppm. Low incidences (750ppm with a defined maternal and developmental toxicity LOAEL of 1500ppm.

  11. Modelling of the photooxidation of toluene: conceptual ideas for validating detailed mechanisms

    Directory of Open Access Journals (Sweden)

    V. Wagner

    2003-01-01

    Full Text Available Toluene photooxidation is chosen as an example to examine how simulations of smog-chamber experiments can be used to unravel shortcomings in detailed mechanisms and to provide information on complex reaction systems that will be crucial for the design of future validation experiments. The mechanism used in this study is extracted from the Master Chemical Mechanism Version 3 (MCM v3 and has been updated with new modules for cresol and g-dicarbonyl chemistry. Model simulations are carried out for a toluene-NOx experiment undertaken at the European Photoreactor (EUPHORE. The comparison of the simulation with the experimental data reveals two fundamental shortcomings in the mechanism: OH production is too low by about 80%, and the ozone concentration at the end of the experiment is over-predicted by 55%. The radical budget was analysed to identify the key intermediates governing the radical transformation in the toluene system. Ring-opening products, particularly conjugated g-dicarbonyls, were identified as dominant radical sources in the early stages of the experiment. The analysis of the time evolution of radical production points to a missing OH source that peaks when the system reaches highest reactivity. First generation products are also of major importance for the ozone production in the system. The analysis of the radical budget suggests two options to explain the concurrent under-prediction of OH and over-prediction of ozone in the model: 1 missing oxidation processes that produce or regenerate OH without or with little NO to NO2 conversion or 2 NO3 chemistry that sequesters reactive nitrogen oxides into stable nitrogen compounds and at the same time produces peroxy radicals. Sensitivity analysis was employed to identify significant contributors to ozone production and it is shown how this technique, in combination with ozone isopleth plots, can be used for the design of validation experiments.

  12. Structural, vibrational, thermal and optical studies of organic single crystal: Benzotriazolium p-toluene sulfonate (BTPTS)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R. Ramesh; Sathya, P.; Gopalakrishnan, R., E-mail: krgkrishnan@yahoo.com [Department of Physics, College of Engineering, Guindy, Anna University, Chennai-600 025 (India)

    2016-05-06

    Benzotriazolium p-toluene sulfonate (BTPTS) was grown by solution growth technique. The powder X-ray diffraction analysis was carried out to evaluate crystal system of the compound. LeBail Profile fitting analysis was performed to extract the individual peak intensities. FTIR spectrum analysis was recorded to study vibration frequencies of the prepared organic salt. Thermal studies were carried out using TG-DSC analysis. Optical absorption and energy band gap of the title compound was evaluated by UV-Vis spectral study.

  13. Statistical modeling for Toluene Diisocyanate and Polypropylene Glycol Polymerization with Ferric Acetylacetonate as Catalyst

    International Nuclear Information System (INIS)

    Semsarzadeh, M. A.; Salehi, H.

    2001-01-01

    Polyurethane elastomer was synthesized with propylene glycol and toluene diisocyanate with ferric acetylacetonate catalyst. This polymerization was modeled using the kinetic equations. The number and weight average degrees of polymerization (DP w and DP n ), the number and weight average molecular weights (M w and M n ) and the polydispersity index parameters were found and tested as function of time and conversion and they were finally compared with GPC laboratory and experimental results. The effect of concentration of the catalyst and the addition sequence of starting materials and catalyst on M n , M w , DPI and M z /M n are reported and discussed

  14. Extraction of lanthanide(3) nitrates by trialkylmethylammonium di-(2-ethylhexyl)phosphate solutions in toluene

    International Nuclear Information System (INIS)

    Pyaertman, A.K.; Kovalev, S.V.; Keskinov, V.A.

    1998-01-01

    Extraction of lanthanide(3) (lanthanum-holmium(3)) nitrates by trialkylmethylammonium di-(2-ethylhexyl)phosphate solutions in toluene (R 4 NA) at T = 298.15 K and pH = 2 is studied. The extraction isotherms are described with an account of formation of compounds of the (R 4 N) 3 [Ln(NO 3 ) 3 A 3 ] and (R 4 N) 2 [Ln(NO 3 ) 3 A 2 ] composition in the organic phase. The extraction constants indices which grow in the series of lanthanum(3)-europium(3) and then reduce to holmium (3) are calculated [ru

  15. Extraction of lanthanide(III) and yttrium(III) nitrates by trialkylbenzylammonium naphthenate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kopyrin, A.A.; Zhikharev, D.A.

    2003-01-01

    Extraction of lanthanides(III) (Ln = La-Nd, Sm-Lu) and yttrium(III) by trialkylbenzylammonium naphthenate in toluene in a wide range of concentrations of the metal nitrates at 298.154 K was studied using the methods of elementary analysis and IR spectroscopy. It was ascertained that the extraction decreases in the series La-Lu, meanwhile yttrium(III) is extracted much worse than lanthanides, The extraction isotherms are described bearing in mind formation in organic phase of complexes featuring composition (R 4 N) 2 [Ln(Y)(NO 3 ) 3 A 2 ], where R = alkyl or benzyl radicals; A naphthenic acid residue [ru

  16. Acid-Free Nitration of Benzene and Toluene in Zeolite NaZSM-5

    OpenAIRE

    Scott J. Kirkby

    2013-01-01

    The syntheses of nitrobenzene and p-nitrotoluene directly from benzene, toluene, and NO2 within the pore network of the initially acid-free zeolite NaZSM-5 are reported for the first time. The active species , formed by the interaction of NO2 with the Na+ cations present on the internal surface, results in the acid-free electrophilic substitution of the aromatic ring. There are two distinct reservoirs for the reagents: one associated with close proximity to the cation sites and the other asso...

  17. Extraction of lanthanide (3) nitrates by trialkylbenzylammonium di(2-ethylhexyl)phosphates in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Keskinov, V.A.; Kovalev, S.V.; Kopyrin, A.A.

    1997-01-01

    A study was made on extraction of lanthanide (3) nitrates [lanthanum-holmium(3)] by trialkylbenzylammonium di(2-ethylhexyl)phosphate in toluene at T=298.15 K and pH 2. Extraction isotherms were described with account of formation of (R 3 N) 3 [LnA 3 (NO 3 ) 3 ] and (R 4 N) 2 [LnA 2 (NO 3 ) 3 ] compounds [A-residue of di(2-ethylhexyl)phosphoric acid] in organic phase. Values of extraction constants, increasing in lanthanum (3)-neodymium (3) series and then decreasing to holmium (3), were calculated. 11 refs., 2 figs., 4 tabs

  18. On the extraction of uranium (VI) from sulphuric acid by toa in toluene

    International Nuclear Information System (INIS)

    Juznic, K.; Fedina, S.

    1975-01-01

    The extraction of U(VI) from sulphuric acid of moderate concentration by tri-octyl amine in toluene has been studied. The results obtained for the uranium distribution ratio on amine and sulphuric acid concentration are examined in terms of the extraction equations and the possible adducts formed in the organic phase. Sulphate concentration in the organic phase was determined indirectly by precipitation with an excess of lead nitrate and subsequent polarographic lead concentration determination. The instruments used were a PO-4 polarograph and CF-4 spectrophotometer. (F.Gy.)

  19. Viscosities of binary mixtures of toluene with butan-1-ol and 2-methylpropan-2-ol

    Directory of Open Access Journals (Sweden)

    VASILE DUMITRESCU

    2005-11-01

    Full Text Available The viscosities of binary liquid mixtures of toluene with butan-1-ol and 2-methylpropan-2-ol have been determined at 298.15, 303.15, 308.15, 313.15 and 318.15 K over the whole concentration range. The Hind, Grunberg–Nissan, Wijk, Auslander and McAllister models were used to calculate the viscosity coefficients and these were compared with the experimental data for the mixtures. Excess viscosities were also calculated and fitted to the Redlich–Kister equation. Various thermodynamic properties of viscous flow activation were determined and their variations with composition are discussed.

  20. Viscosity of magnetite-toluene nanofluids: Dependence on temperature and nanoparticle concentration

    Science.gov (United States)

    Singh, Rahul; Sanchez, Oswaldo; Ghosh, Suvojit; Kadimcherla, Naveen; Sen, Swarnendu; Balasubramanian, Ganesh

    2015-10-01

    We examine the dependence of the viscosity of nanofluids, comprised of magnetite nanoparticles dispersed in toluene, on particle concentration and temperature. The nanofluid viscosity increases monotonically with particle concentration. We show that although the nanoparticles aggregate to form clusters with increasing concentration, the cluster size is fairly monodisperse and hence the viscosity can be expressed as a function of only the particle concentration. The viscosity of the nanofluid is found to decrease with temperature, similarly to the characteristics of the carrier liquid. We describe these dependencies through an empirical correlation, since the observations are useful to employ such nanofluids in engineering applications.

  1. Electrodeposition of polypyrrole films on aluminum surfaces from a p-toluene sulfonic acid medium

    Directory of Open Access Journals (Sweden)

    Andréa Santos Liu

    2009-01-01

    Full Text Available Electrodeposition of polypyrrole films on aluminum from aqueous solutions containing p-toluene sulfonic acid and pyrrole was performed by cyclic voltammetry and galvanostatic technique. The influence of applied current density on the morphology of the films was studied by Scanning Electron Microscopy. The films displayed a cauliflower-like structure consisting of micro-spherical grains. This structure is related to dopand intercalation in the polymeric chain. Films deposited at higher current density were more susceptible to the formation of pores and defects along the polymeric chain than films deposited at lower current density. These pores allow the penetration of aggressive species, thereby favoring the corrosion process.

  2. [原著]The Effects of Ethanol or Toluene on Plasma Lipids, Essential Amino Acids and Fatty Infiltration of the Liver in Wistar Male Rats

    OpenAIRE

    Dominicus, Dalmas A. R.; Department of Preventive Medicine, School of Medicine. University of the Ryukyus

    1991-01-01

    To investigate the differenoe between the effect of alcohol (ethanol) and toluene on the plasma lipids, essential amino acids and fatty infiltration of the liver, a study was done for two months involving male wistar rats. Ethanol, 20 rats, divided into L1 (ethanol 2.5g/kg body wt), L2 (ethanol 1.25g/kg body wt) and PF, control, received isocaloric glucose and food equal to the amount taken by LI. Toluene, 20 rats, divided into 10 toluene exposed rats (Te) , 900 ppm of toluene vapour in the c...

  3. 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.

  4. [Synergetic effects of silicon carbide and molecular sieve loaded catalyst on microwave assisted catalytic oxidation of toluene].

    Science.gov (United States)

    Wang, Xiao-Hui; Bo, Long-Li; Liu, Hai-Nan; Zhang, Hao; Sun, Jian-Yu; Yang, Li; Cai, Li-Dong

    2013-06-01

    Molecular sieve loaded catalyst was prepared by impregnation method, microwave-absorbing material silicon carbide and the catalyst were investigated for catalytic oxidation of toluene by microwave irradiation. Research work examined effects of silicon carbide and molecular sieve loading Cu-V catalyst's mixture ratio as well as mixed approach changes on degradation of toluene, and characteristics of catalyst were measured through scanning electron microscope, specific surface area test and X-ray diffraction analysis. The result showed that the fixed bed reactor had advantages of both thermal storage property and low-temperature catalytic oxidation when 20% silicon carbide was filled at the bottom of the reactor, and this could effectively improve the utilization of microwave energy as well as catalytic oxidation efficiency of toluene. Under microwave power of 75 W and 47 W, complete-combustion temperatures of molecular sieve loaded Cu-V catalyst and Cu-V-Ce catalyst to toluene were 325 degrees C and 160 degrees C, respectively. Characteristics of the catalysts showed that mixture of rare-earth element Ce increased the dispersion of active components in the surface of catalyst, micropore structure of catalyst effectively guaranteed high adsorption capacity for toluene, while amorphous phase of Cu and V oxides increased the activity of catalyst greatly.

  5. Fungal biofilters for toluene biofiltration: evaluation of the performance with four packing materials under different operating conditions.

    Science.gov (United States)

    Maestre, Juan P; Gamisans, Xavier; Gabriel, David; Lafuente, Javier

    2007-03-01

    Packing materials play a key role in the performance of bioreactors for waste gas treatment and particularly in biofilter applications. In this work, the performance of four differently packed biofilters operated in parallel for the treatment of relatively high inlet concentration of toluene was studied. The reactors were compared for determining the suitability of coconut fiber, digested sludge compost from a waste water treatment plant, peat and pine leaves as packing materials for biofiltration of toluene. A deep characterisation of materials was carried out. Biological activity and packing capabilities related to toluene removal were determined throughout 240 days of operation under different conditions of nutrients addition and watering regime. Also, biofilters recovering after a short shutdown was investigated. Nutrient addition resulted in improved removal efficiencies (RE) and elimination capacities (EC) of biofilters reaching maximum ECs between 75 and 95 g m(-3)h(-1) of toluene. In the first 80 days, the pH decreased progressively within the reactors, causing a population change from bacteria to fungi, which were the predominant decontaminant microorganisms thereafter. All reactors were found to recover the RE rapidly after a 5 days shutdown and, in a maximum of 7 days, all reactors had been completely recuperated. These results point out that fungal biofilters are a suitable choice to treat high loads of toluene. In general, coconut fiber and compost biofilters exhibited a better performance in terms of elimination capacity and long-term stability.

  6. Removal of benzene and toluene from a refinery waste air stream by water sorption and biotrickling filtration

    Directory of Open Access Journals (Sweden)

    Paolo Viotti

    2015-11-01

    Full Text Available The paper presents the results of an analysis of a two-stage pilot plant for the removal of toluene and benzene from the exhaust air of an industrial wastewater treatment plant (WWTP. The two-stage air process combines a water scrubber and a biotrickling filter (BTF in sequence, and treats air stripped from the liquid phase compartments of the WWTP. During the experimental period, the pilot plant treated an airflow of 600 Nm3h-1. Average concentrations of the waste air stream entering the water scrubber were 10.61 mg Nm-3 benzene and 9.26 mg Nm-3 toluene. The water scrubber obtained medium-high removal efficiencies (averages 51% and 60%, for benzene and toluene, respectively. Subsequent passage through the BTF allowed a further reduction of average concentrations, which decreased to 2.10 mg Nm-3 benzene and to 0.84 mg Nm-3 toluene, thereby allowing overall average removal efficiencies (REs of 80% and 91% for benzene and toluene, respectively. Results prove the benefits obtained from a combination of different removal technologies: water scrubbers to remove peak concentrations and soluble compounds, and BTFs to remove compounds with lower solubility, due to the biodegradation performed by microorganisms.

  7. Biotransformation of d-Limonene to (+) trans-Carveol by Toluene-Grown Rhodococcus opacus PWD4 Cells

    Science.gov (United States)

    Duetz, Wouter A.; Fjällman, Ann H. M.; Ren, Shuyu; Jourdat, Catherine; Witholt, Bernard

    2001-01-01

    The toluene-degrading strain Rhodococcus opacus PWD4 was found to hydroxylate d-limonene exclusively in the 6-position, yielding enantiomerically pure (+) trans-carveol and traces of (+) carvone. This biotransformation was studied using cells cultivated in chemostat culture with toluene as a carbon and energy source. The maximal specific activity of (+) trans-carveol formation was 14.7 U (g of cells [dry weight])−1, and the final yield was 94 to 97%. Toluene was found to be a strong competitive inhibitor of the d-limonene conversion. Glucose-grown cells did not form any trans-carveol from d-limonene. These results suggest that one of the enzymes involved in toluene degradation is responsible for this allylic monohydroxylation. Another toluene degrader (Rhodococcus globerulus PWD8) had a lower specific activity but was found to oxidize most of the formed trans-carveol to (+) carvone, allowing for the biocatalytic production of this flavor compound. PMID:11375201

  8. [Determination of residual toluene diisocyanate in sponge bra by gas chromatography].

    Science.gov (United States)

    Wang, Aixia; Ye, Ping; Huang, Nan; Chen, Yan; Li, Xinggen

    2017-06-08

    A gas chromatography (GC) with internal standard method was developed for the determination of residual toluene diisocyanate (TDI) in sponge bra. The samples were extracted with ethyl acetate dehydrated, and cleaned up with 0.22 μm microfiltration membrane. The residual toluene diisocyanate was separated on a DB-624 capillary column using temperature programming. The flame ionization detector (FID) was used at 250 ℃. The inlet temperature was 180 ℃ with nitrogen as carrier gas. The linear range was 10-200 mg/L ( R 2 =0.9989) for TDI. The average recovery ranged from 80.5% to 91.6% with RSD not more than 7.9%( n =6). The limit of detection (LOD) and limit of quantification (LOQ) were 10 mg/kg and 100 mg/kg, respectively. The developed method was then utilized to analyse the 100 batches of sponge bra samples from the manufacturing enterprises, the entity shops and electric business platforms. The method is simple, time-saving and environment friendly with high sensitivity and good reproducibility, and has practical application value due to its low-cost and short-circle.

  9. Biodegradation of vapor-phase toluene in unsaturated porous media: Column experiments.

    Science.gov (United States)

    Khan, Ali M; Wick, Lukas Y; Harms, Hauke; Thullner, Martin

    2016-04-01

    Biodegradation of organic chemicals in the vapor phase of soils and vertical flow filters has gained attention as promising approach to clean up volatile organic compounds (VOC). The drivers of VOC biodegradation in unsaturated systems however still remain poorly understood. Here, we analyzed the processes controlling aerobic VOC biodegradation in a laboratory setup mimicking the unsaturated zone above a shallow aquifer. The setup allowed for diffusive vapor-phase transport and biodegradation of three VOC: non-deuterated and deuterated toluene as two compounds of highly differing biodegradability but (nearly) identical physical and chemical properties, and MTBE as (at the applied experimental conditions) non-biodegradable tracer and internal control. Our results showed for toluene an effective microbial degradation within centimeter VOC transport distances despite high gas-phase diffusivity. Degradation rates were controlled by the reactivity of the compounds while oxic conditions were found everywhere in the system. This confirms hypotheses that vadose zone biodegradation rates can be extremely high and are able to prevent the outgassing of VOC to the atmosphere within a centimeter range if compound properties and site conditions allow for sufficiently high degradation rates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Test of vanadium pentoxide as anode for the electrooxidation of toluene

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, L.F. [Petroleos de Venezuela - Intevep, Caracas (Venezuela). Departamento de Tecnologias Emergentes; Rincon, L.; Ortiz, R. [Universidad de los Andes, Merida (Venezuela). Departamento de Quimica

    2004-11-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) films were prepared by electrochemical and thermal decomposition of vanadyl sulphate on titanium dioxide covered titanium plates and glassy carbon discs. The prepared material by thermal decomposition showed high surface area and good physical stability; while the electrodeposited films, although being homogeneous, showed poor adhesion. The V{sub 2}O{sub 5} electrodes were chemically and electrochemically stable in aqueous (1 M H{sub 2}SO{sub 4} + 1 M NaOH, pH 3) and organic (0.1 M But{sub 4}NPF{sub 6} + CH{sub 3}CN) solutions. In both cases, a well defined electrochemical response was observed. At the experimental conditions, the prepared materials were not active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the V{sub 2} O{sub 5} surface. (author)

  11. Test of vanadium pentoxide as anode for the electrooxidation of toluene

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, Luis F. [Petroleos de Venezuela (PDVSA)-Intevep, Departamento de Tecnologias Emergentes, Apartado 76343, Caracas 1070-A (Venezuela)]. E-mail: delialf@pdvsa.com; Rincon, L. [Universidad de los Andes, Facultad de Ciencias, Departamento de Quimica, Grupo de Quimica Teorica, Merida 5101 (Venezuela); Ortiz, R. [Universidad de los Andes, Facultad de Ciencias, Departamento de Quimica, Laboratorio de Electroquimica, Merida 5101 (Venezuela)

    2004-11-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) films were prepared by electrochemical and thermal decomposition of vanadyl sulphate on titanium dioxide covered titanium plates and glassy carbon discs. The prepared material by thermal decomposition showed high surface area and good physical stability; while the electrodeposited films, although being homogeneous, showed poor adhesion. The V{sub 2}O{sub 5} electrodes were chemically and electrochemically stable in aqueous (1 M H{sub 2}SO{sub 4} + 1 M NaOH, pH 3) and organic (0.1 M But{sub 4}NPF{sub 6} + CH{sub 3}CN) solutions. In both cases, a well defined electrochemical response was observed. At the experimental conditions, the prepared materials were not active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the V{sub 2}O{sub 5} surface.

  12. New determination method of radon-220 in water by toluene extraction and liquid scintillation counter

    International Nuclear Information System (INIS)

    Horiuchi, Kimiko; Murakami, Yukio

    1979-01-01

    220 Rn in mineral springs is easily extracted into toluene solution (containing a definite amount of liquid scientillator), which is carefuly transferred into counting vial. The activity in the solution is measured by integral counting technique with a liquid scintillation counter. 220 Rn, being extracted, rapidly disappears but 212 Pb (half-life 10.64 h) and its descendants form a radioactive equilibrium in toluene solution around 3.7 h after the extraction. The establishment of radioactive equilibrium is proved by α and β rays energy spectrum and also by the formation of growth decay curve. The shape of this curve entirely coincides with decay curve constructed by application of the Bateman equations for 212 Pb and its descendants. It was proved that integral counting technique could practically give hundred percent counting efficiency for 1α and 2β emitters in radioactive equilibrium. A calculating formula for 220 Rn contents in water is proposed based upon these facts, together with necessary correction terms such as extractability, decay rate during measurement and so on. The detection limits of this method is found as (6.8 +- 0.9) x 10 -10 Ci (standard deviation incounting) under the conditions of 5 cpm (one tenth of background counting rate) and total counting time of 400 min. Some practical examples of determination of 220 Rn in mineral springs are shown together with 222 Rn contents to prove the availability and feasibility of this method. (author)

  13. Biocomplementation of SVE to achieve clean-up goals in soils contaminated with toluene and xylene.

    Science.gov (United States)

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

    2013-10-01

    Soil vapor extraction (SVE) and bioremediation (BR) are two of the most common soil remediation technologies. Their application is widespread; however, both present limitations, namely related to the efficiencies of SVE on organic soils and to the remediation times of some BR processes. This work aimed to study the combination of these two technologies in order to verify the achievement of the legal clean-up goals in soil remediation projects involving seven different simulated soils separately contaminated with toluene and xylene. The remediations consisted of the application of SVE followed by biostimulation. The results show that the combination of these two technologies is effective and manages to achieve the clean-up goals imposed by the Spanish Legislation. Under the experimental conditions used in this work, SVE is sufficient for the remediation of soils, contaminated separately with toluene and xylene, with organic matter contents (OMC) below 4 %. In soils with higher OMC, the use of BR, as a complementary technology, and when the concentration of contaminant in the gas phase of the soil reaches values near 1 mg/L, allows the achievement of the clean-up goals. The OMC was a key parameter because it hindered SVE due to adsorption phenomena but enhanced the BR process because it acted as a microorganism and nutrient source.

  14. Enhanced biofilm production by a toluene-degrading Rhodococcus observed after exposure to perfluoroalkyl acids.

    Science.gov (United States)

    Weathers, Tess S; Higgins, Christopher P; Sharp, Jonathan O

    2015-05-05

    This study focuses on interactions between aerobic soil-derived hydrocarbon degrading bacteria and a suite of perfluorocarboxylic acids and perfluoroalkylsulfonates that are found in aqueous film-forming foams used for fire suppression. No effect on toluene degradation rate or induction time was observed when active cells of Rhodococcus jostii strain RHA1 were exposed to toluene and a mixture of perfluoroalkyl acids (PFAAs) including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) at concentrations near the upper bounds of groundwater relevance (11 PFAAs at 10 mg/L each). However, exposure to aqueous PFAA concentrations above 2 mg/L (each) was associated with enhanced aggregation of bacterial cells and significant increases in extracellular polymeric substance production. Flocculation was only observed during exponential growth and not elicited when PFAAs were added to resting incubations; analogous flocculation was also observed in soil enrichments. Aggregation was accompanied by 2- to 3-fold upregulation of stress-associated genes, sigF3 and prmA, during growth of this Rhodococcus in the presence of PFAAs. These results suggest that biological responses, such as microbial stress and biofilm formation, could be more prominent than suppression of co-contaminant biodegradation in subsurface locations where poly- and perfluoroalkyl substances occur with hydrocarbon fuels.

  15. Supercritical CO2 fluid radiochromatography system used to purify [11C]toluene for PET

    International Nuclear Information System (INIS)

    Muller, Ryan D.; Ferrieri, Richard A.; Gerasimov, Madina; Garza, Victor

    2002-01-01

    Abuse of inhalants in today's society has become such a widespread problem among today's adolescents that in many parts of the world their use exceeds that of many other illicit drugs or alcohol. Even so, little is known how such inhalants affect brain function to an extent that can lead to an abuse liability. While methodologies exist for radiolabeling certain inhalants of interest with short-lived positron emitting radioisotopes that would allow their investigation in human subjects using positron emission tomography (PET), the purification methodologies necessary to separate these volatile substances from the organic starting materials have not been developed. We've adapted supercritical fluid technology to this specific PET application by building a preparative-scale supercritical CO 2 fluid radiochromatograph, and applied it to the purification of [ 11 C]toluene. We've demonstrated that [ 11 C]toluene can be separated from the starting materials using a conventional C 18 HPLC column and pure supercritical CO 2 fluid as the mobile phase operating at 2000 psi and 40 deg. C. We've also shown that the purified radiotracer can be quantitatively captured on Tenax GR, a solid support material, as it exits the supercritical fluid stream, thus allowing for later desorption into a 1.5% cyclodextrin solution that is suitable for human injection, or into a breathing tube for direct inhalation

  16. Pulse radiolyses of anthraquinone and anthraquinone-triethylamine in acetonitrile and toluene at room temperature

    International Nuclear Information System (INIS)

    Nakayama, Toshihiro; Ushida, Kiminori; Hamanoue, Kumao; Washio, Masakazu; Tagawa, Seiichi; Tabata, Yoneho

    1990-01-01

    Nanosecond pulse radiolysis of anthraquinone (AQ) in several solvents has been performed at room temperature, and the following results are obtained: (1) in acetonitrile (CH 3 CN), the formation of triplet AQ and a free-radical anion (AQ .- ) of AQ is observed. The former is produced by energy transfer from an excited neutral of CH 3 CN which may be produced via the geminate recombination of a radical cation and a radical anion of CH 3 CN in a spur, while the latter is produced by electron transfer from anionic species such as a solvated electron, a monomeric and/or a dimeric radical anion of CH 3 CN. In CH 3 CN-triethylamine (TEA), both free AQ .- and triplet AQ mentioned above are also produced; however, the latter reacts with TEA, giving rise to the formation of free AQ .- (from the second triplet state of AQ) and an exciplex of the lowest triplet state of AQ with ground-state TEA. This exciplex decomposes to free AQ .- and the radical cation of TEA. (2) In toluene, only triplet AQ is produced by energy transfer from triplet toluene to AQ, and, in the presence of TEA, the formation of the triplet exciplex of AQ-TEA is observed. On a microsecond timescale, however, this exciplex changes to a contact ion pair followed by proton transfer, generating anthrasemiquinone radical and triethylamine radical in accordance with the result of photolysis. (author)

  17. Start-up and performance characteristics of a trickle bed reactor degrading toluene

    Directory of Open Access Journals (Sweden)

    Ondrej Misiaczek

    2007-09-01

    Full Text Available The objective of this work was to evaluate toluene degradation in a trickle bed reactor when the loading was carried out by changing the air flow rate. The biofiltration system was inoculated with a mixed microbial population, adapted to degradation of hydrophobic compounds. Polypropylene high flow rings were used as a packing material. The system was operated for a period of 50 days at empty bed residence times ranging from 106s to 13s and with a constant inlet concentration of toluene of 100 mg.m-3. The reactor showed high removal efficiency at higher contact times and increasing elimination capacity with higher air-flow rates. The highest EC value reached was 9.8 gC.m-3.h-1 at EBRT = 13s. During the experiment, the consumption of NaOH solution was also measured. No significant variation of this value was found and an average value of 3.84 mmol of NaOH per gram of consumed carbon was recorded.

  18. Effects of prenatal exposure to toluene on postnatal development and behavior in rats

    DEFF Research Database (Denmark)

    Hougaard, K. S.; Hass, Ulla; Lund, S. P.

    1999-01-01

    Development and neurobehavioral effects of prenatal exposure to toluene (CAS 108-88-3) were studied after exposing pregnant rats (Mol:WIST) to 1800 ppm of the solvent for 6 h daily on days 7-20 of gestation. Body weights of exposed offspring were lower until day 10 after parturition. Neurobehavio......Development and neurobehavioral effects of prenatal exposure to toluene (CAS 108-88-3) were studied after exposing pregnant rats (Mol:WIST) to 1800 ppm of the solvent for 6 h daily on days 7-20 of gestation. Body weights of exposed offspring were lower until day 10 after parturition....... Neurobehavioral evaluation of the pups revealed no effects on motor function (rotarod), activity level (open field), acoustic startle, and prepulse inhibition. Measurements of hearing function using auditory brain stem response revealed small effects in male-exposed offspring. Performance in a Morris water maze...... during initial learning gave some indications of impaired cognitive functions, which was confirmed during further testing, especially in reversal and new learning. Effects on cognitive functions seemed most marked in female offspring. (C) 1999 Elsevier Science Inc. All rights reserved....

  19. Cu-Mn-Ce ternary mixed-oxide catalysts for catalytic combustion of toluene.

    Science.gov (United States)

    Lu, Hanfeng; Kong, Xianxian; Huang, Haifeng; Zhou, Ying; Chen, Yinfei

    2015-06-01

    Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the CeO2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species. Copyright © 2015. Published by Elsevier B.V.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-12

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

  1. 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)

  2. Recovery of high purity sulfuric acid from the waste acid in toluene nitration process by rectification.

    Science.gov (United States)

    Song, Kai; Meng, Qingqiang; Shu, Fan; Ye, Zhengfang

    2013-01-01

    Waste sulfuric acid is a byproduct generated from numerous industrial chemical processes. It is essential to remove the impurities and recover the sulfuric acid from the waste acid. In this study the rectification method was introduced to recover high purity sulfuric acid from the waste acid generated in toluene nitration process by using rectification column. The waste acid quality before and after rectification were evaluated using UV-Vis spectroscopy, GC/MS, HPLC and other physical and chemical analysis. It was shown that five nitro aromatic compounds in the waste acid were substantially removed and high purity sulfuric acid was also recovered in the rectification process at the same time. The COD was removed by 94% and the chrominance was reduced from 1000° to 1°. The recovered sulfuric acid with the concentration reaching 98.2 wt% had a comparable quality with commercial sulfuric acid and could be recycled back into the toluene nitration process, which could avoid waste of resources and reduce the environmental impact and pollution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Vertically-oriented graphenes supported Mn3O4 as advanced catalysts in post plasma-catalysis for toluene decomposition

    Science.gov (United States)

    Bo, Zheng; Hao, Han; Yang, Shiling; Zhu, Jinhui; Yan, Jianhua; Cen, Kefa

    2018-04-01

    This work reports the catalytic performance of vertically-oriented graphenes (VGs) supported manganese oxide catalysts toward toluene decomposition in post plasma-catalysis (PPC) system. Dense networks of VGs were synthesized on carbon paper (CP) via a microwave plasma-enhanced chemical vapor deposition (PECVD) method. A constant current approach was applied in a conventional three-electrode electrochemical system for the electrodeposition of Mn3O4 catalysts on VGs. The as-obtained catalysts were characterized and investigated for ozone conversion and toluene decomposition in a PPC system. Experimental results show that the Mn3O4 catalyst loading mass on VG-coated CP was significantly higher than that on pristine CP (almost 1.8 times for an electrodeposition current of 10 mA). Moreover, the decoration of VGs led to both enhanced catalytic activity for ozone conversion and increased toluene decomposition, exhibiting a great promise in PPC system for the effective decomposition of volatile organic compounds.

  4. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro, Serguei [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco (Chile); Valdés, Héctor, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Manéro, Marie-Hélène [Université de Toulouse (France); INPT, UPS (France); Laboratoire de Génie Chimique, 4, Allée Emile Monso, F–31030 Toulouse (France); CNRS (France); Laboratoire de Génie Chimique, F–31030 Toulouse (France); Zaror, Claudio A. [Departamento de Ingeniería Química (F. Ingeniería), Universidad de Concepción, Concepción, Correo 3, Casilla 160–C (Chile)

    2014-06-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  5. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    International Nuclear Information System (INIS)

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A.

    2014-01-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity

  6. Modulatory Effect of Baphia Nitida Dye in Toluene Induced Cytogenotoxicity, Hematotoxicity and Histopathology in Dermal Exposed Wistar Rats

    Directory of Open Access Journals (Sweden)

    Chibuisi Gideon Alimba

    2015-03-01

    Full Text Available Background: There is unprecedented increase in the processing and packaging of many plant materials into food supplements, herbal medicine, skincare and cosmetic products for human needs. Baphia nitida is used for topical skincare products. Toluene, a toxic aromatic solvent, is increasingly being used in the production of these skincare and cosmetic products in many industries. This study assessed toluene toxicological profile and the ability of Baphia nitida dye to ameliorate toluene induced cytogenotoxicity, hematotoxicity and histopathological effects in rats. Methods: Rats were treated with various concentrations; 0, 1000, 2000 and 5000 mg of the aqueous, ethanol and toluene processed B. nitida dye via dermal exposure for acute and sub-lethal toxicity. 96 h acute toxicity was assessed for the solvents. Micronuclei induction, alterations in hematological indices and erythrocyte morphology and skin histology were assessed after sub-lethal treatment. Results: 96 h LD50 of B. nitida processed dye for the three solvents were indeterminate. There was insignificant (p>0.05 alterations in the hematological indices and erythrocyte morphology, induction of micronucleated polychromatic erythrocyte and polychromatic and normochromatic erythrocyte ratio in the aqueous and ethanol processed B. nitida treated rats compared to their corresponding controls. Toluene induced significant (p<0.05 decrease in erythrocytes count, hematocrit and leucocytes, increased micronucleated PCE, decreased PCE/NCE ratio and induced necrosis, thick dermal layer and dispersed areolar tissues in treated rats. But, these effects were ameliorated by the B. nitida dye. Conclusion: Camwood dye protects against toluene induced toxicity in rats. This suggests its relative safety in topical cosmetic and skincare production.

  7. Extremely low-level microwaves attenuate immune imbalance induced by inhalation exposure to low-level toluene in mice.

    Science.gov (United States)

    Novoselova, Elena G; Glushkova, Olga V; Khrenov, Maxim O; Novoselova, Tatyana V; Lunin, Sergey M; Fesenko, Eugeny E

    2017-05-01

    To clarify whether extremely low-level microwaves (MW) alone or in combination with p38 inhibitor affect immune cell responses to inhalation exposure of mice to low-level toluene. The cytokine profile, heat shock proteins expression, and the activity of several signal cascades, namely, NF-κB, SAPK/JNK, IRF-3, p38 MAPK, and TLR4 were measured in spleen lymphocytes of mice treated to air-delivered toluene (0.6 mg/m 3 ) or extremely low-level microwaves (8.15-18 GHz, 1μW/cm 2 , 1 Hz swinging frequency) or combined action of these two factors. A single exposure to air-delivered low-level toluene induced activation of NF-κB, SAPK/JNK, IFR-3, p38 MAPK and TLR4 pathways. Furthermore, air toluene induced the expression of Hsp72 and enhanced IL-1, IL-6, and TNF-α in blood plasma, which is indicative of a pro-inflammatory response. Exposure to MW alone also resulted in the enhancement of the plasma cytokine values (e.g. IL-6, TNF-α, and IFN-γ) and activation of the NF-κB, MAPK p38, and especially the TLR4 pathways in splenic lymphocytes. Paradoxically, pre-exposure to MW partially recovered or normalized the lymphocyte parameters in the toluene-exposed mice, while the p38 inhibitor XI additionally increased protective activity of microwaves by down regulating MAPKs (JNK and p38), IKK, as well as expression of TLR4 and Hsp90-α. The results suggest that exposure to low-intensity MW at specific conditions may recover immune parameters in mice undergoing inhalation exposure to low-level toluene via mechanisms involving cellular signaling.

  8. Hybrid plasma-catalytic steam reforming of toluene as a biomass tar model compound over Ni/Al₂O₃ catalysts

    OpenAIRE

    Liu, SY; Mei, DH; Nahil, MA; Gadkari, S; Gu, S; Williams, PT; Tu, X

    2017-01-01

    In this study, plasma-catalytic steam reforming of toluene as a biomass tar model compound was carried out in a coaxial dielectric barrier discharge (DBD) plasma reactor. The effect of Ni/Al2O3 catalysts with different nickel loadings (5–20 wt%) on the plasma-catalytic gas cleaning process was evaluated in terms of toluene conversion, gas yield, by-products formation and energy efficiency of the plasma-catalytic process. Compared to the plasma reaction without a catalyst, the combination of D...

  9. pKJ1, a naturally occurring conjugative plasmid coding for toluene degradation and resistance to streptomycin and sulfonamides

    Energy Technology Data Exchange (ETDEWEB)

    Yano, K.; Nishi, T.

    1980-08-01

    Pseudomonas sp. TA8 isolated by m-toluate enrichment from an aqueous sample metabolized toluene and m- and p-xylenes via the meta cleavage pathway, and manifested specific resistance to streptomycin and sulfonamides. A variety of experiments revealed that the pKJ1 plasmid of about 150 megadaltons carried by TA8 specified both the toluene and xylene degradative function (the Tol function) and streptomycin/sulfonamide resistance. The deletion of a segment of pKJ1 (about 22 megadaltons) resulted in the loss of the Tol function. pKJ1 was not assigned to Pseudomonas incompatibility group P-1, P-2, P-3, or P-9.

  10. Isolation and characterization of Magnetospirillum sp strain 15-1 as a representative anaerobic toluene-degrader from a constructed wetland model

    DEFF Research Database (Denmark)

    Meyer-Cifuentes, Ingrid; Lavanchy, Paula Maria Martinez; Marin-Cevada, Vianey

    2017-01-01

    Previously, Planted Fixed-Bed Reactors (PFRs) have been used to investigate microbial toluene removal in the rhizosphere of constructed wetlands. Aerobic toluene degradation was predominant in these model systems although bulk redox conditions were hypoxic to anoxic. However, culture-independent ...

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

    NARCIS (Netherlands)

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

    2002-01-01

    The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene,

  12. Solid-vapour reactions as a post-synthetic modification tool for molecular crystals: the enclathration of benzene and toluene by Werner complexes.

    Science.gov (United States)

    Lusi, Matteo; Barbour, Leonard J

    2013-04-04

    The enclathration of benzene and toluene by Werner complexes has been described. In the case of toluene, time-lapse PXRD analysis reveals that solid-liquid and solid-vapour reactions proceed according to different pathways. These preliminary results suggest that solid-liquid reactions destroy the host structure, whereas the solid-vapour reactions allow post-synthetic modification.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-06-01

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

  14. Low-temperature chemical vapor deposition growth of graphene from toluene on electropolished copper foils.

    Science.gov (United States)

    Zhang, Bin; Lee, Wi Hyoung; Piner, Richard; Kholmanov, Iskandar; Wu, Yaping; Li, Huifeng; Ji, Hengxing; Ruoff, Rodney S

    2012-03-27

    A two-step CVD route with toluene as the carbon precursor was used to grow continuous large-area monolayer graphene films on a very flat, electropolished Cu foil surface at 600 °C, lower than any temperature reported to date for growing continuous monolayer graphene. Graphene coverage is higher on the surface of electropolished Cu foil than that on the unelectropolished one under the same growth conditions. The measured hole and electron mobilities of the monolayer graphene grown at 600 °C were 811 and 190 cm(2)/(V·s), respectively, and the shift of the Dirac point was 18 V. The asymmetry in carrier mobilities can be attributed to extrinsic doping during the growth or transfer. The optical transmittance of graphene at 550 nm was 97.33%, confirming it was a monolayer, and the sheet resistance was ~8.02 × 10(3) Ω/□. © 2012 American Chemical Society

  15. Fabrication of Ordered Nanopattern by using ABC Triblock Copolymer with Salt in Toluene

    Science.gov (United States)

    Huang, Hailiang; Zhong, Benbin; Zu, Xihong; Luo, Hongsheng; Lin, Wenjing; Zhang, Minghai; Zhong, Yazhou; Yi, Guobin

    2017-08-01

    Ordered nanopatterns of triblock copolymer polystyrene- block-poly(2-vinylpyridine)- block- poly (ethylene oxide)(PS- b-P2VP- b-PEO) have been achieved by the addition of lithium chloride (LiCl). The morphological and structural evolution of PS- b-P2VP- b-PEO/LiCl thin films were systematically investigated by varying different experimental parameters, including the treatment for polymer solution after the addition of LiCl, the time scale of ultrasonic treatment and the molar ratio of Li+ ions to the total number of oxygen atoms (O) in PEO block and the nitrogen atoms (N) in P2VP block. When toluene was used as the solvent for LiCl, ordered nanopattern with cylinders or nanostripes could be obtained after spin-coating. The mechanism of nanopattern transformation was related to the loading of LiCl in different microdomains.

  16. Involving High School Students in Computational Physics University Research: Theory Calculations of Toluene Adsorbed on Graphene.

    Science.gov (United States)

    Ericsson, Jonas; Husmark, Teodor; Mathiesen, Christoffer; Sepahvand, Benjamin; Borck, Øyvind; Gunnarsson, Linda; Lydmark, Pär; Schröder, Elsebeth

    2016-01-01

    To increase public awareness of theoretical materials physics, a small group of high school students is invited to participate actively in a current research projects at Chalmers University of Technology. The Chalmers research group explores methods for filtrating hazardous and otherwise unwanted molecules from drinking water, for example by adsorption in active carbon filters. In this project, the students use graphene as an idealized model for active carbon, and estimate the energy of adsorption of the methylbenzene toluene on graphene with the help of the atomic-scale calculational method density functional theory. In this process the students develop an insight into applied quantum physics, a topic usually not taught at this educational level, and gain some experience with a couple of state-of-the-art calculational tools in materials research.

  17. Selective adsorption of toluene-3,4-dithiol on Si(553)-Au surfaces

    Science.gov (United States)

    Suchkova, Svetlana; Hogan, Conor; Bechstedt, Friedhelm; Speiser, Eugen; Esser, Norbert

    2018-01-01

    The adsorption of small organic molecules onto vicinal Au-stabilized Si(111) surfaces is shown to be a versatile route towards controlled growth of ordered organic-metal hybrid one-dimensional nanostructures. Density functional theory is used to investigate the site-specific adsorption of toluene-3,4-dithiol (TDT) molecules onto the clean Si(553)-Au surface and onto a co-doped surface whose steps are passivated by hydrogen. We find that the most reactive sites involve bonding to silicon at the step edge or on the terraces, while gold sites are relatively unfavored. H passivation and TDT adsorption both induce a controlled charge redistribution within the surface layer, causing the surface metallicity, electronic structure, and chemical reactivity of individual adsorption sites to be substantially altered.

  18. Kinetics of Cobalt (II) Extraction by Alamine-336 in Toluene from Hydrochloric Acid Solutions

    International Nuclear Information System (INIS)

    Tadros, N.A.; Abdel-Fattah, A.A.

    2000-01-01

    Solvent extraction behaviour of Co(II) by a tertiary amine, alamine-336 dissolved in toluene was investigated from hydrochloric acid solutions. The equilibrium constant of extraction, K , x, as well as the free energy (Delta G) were determined under the experimental conditions. Kinetic studies were performed on the extraction process. In this concern, the order of reaction with respect to each of the participating reactants, as well as the overall order were determined experimentally, using the technique of initial rates. Accordingly, the rate law of the extraction process was formulated and the specific rate constant was determined. The mechanism through which the reaction may proceed was postulated and the rate determining step was determined according to the deduced rate law. Consequently, the overall stoichiometric equation expressing the extraction process was confirmed. The standard deviations were calculated, and the obtained data were discussed and explained

  19. Extraction of U(VI) with unsymmetrical N-methyl-N-decylalkylamide in toluene

    International Nuclear Information System (INIS)

    Yu Cui; Guoxin Sun; Zhenwei Zhang; Yexin Li; Sixiu Sun

    2005-01-01

    A number of structurally related new unsymmetrical monoamides with different substituting groups, N-methyl-N-decyloctylamide (MDOA), N-methyl-N-decyldecanamide (MDDA), and N-methyl-N-decyldodecanamide (MDDOA), were synthesized. The extraction of U(VI) from nitric acid medium by the synthesized monoamides diluted with toluene was investigated. The effect of nitric acid concentration, sodium nitrate concentration, extractant concentration and temperature on the distribution ratio was studied. The stoichiometry of the main extracted species confirms to UO 2 (NO 3 ) 2 .2A (A, amidic extractant). The values of thermodynamic parameters were determined and the extraction reactions were found exothermic. The IR spectral study was also made of the extracted species. (orig.)

  20. Structural effect of N,N-dialkylamide in toluene on the extraction of uranium(VI)

    International Nuclear Information System (INIS)

    Sun, Guo-Xin; Han, Jing-Tian; Bao, Bo-Rong; Sun, Si-Xiu

    1998-01-01

    N,N-dialkylamides having ethyl (DEDOA), butyl (DBDOA) and octyl (DODOA) groups as the alkyl substituents were synthesized in order to investigate their selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction distribution coefficients of U(VI) with the amides in toluene decrease in the order of DODOA > DBDOA > DEDOA. The structure of the extracted species was suggested from the dependence of the distribution ratio on the concentration of the extractant, with the aid of FT-IR spectra. The structural effect on the extraction capability of U(VI) was discussed in terms of the molecular modelling. The effects of temperature on the distribution ratios were also considered, and the extraction reaction enthalpy was calculated. (author)

  1. Effects of prenatal exposure to chronic mild stress and toluene in rats

    DEFF Research Database (Denmark)

    Hougaard, Karin; Andersen, Maibritt B; Hansen, Ase M

    2005-01-01

    The aim of the present study was to elucidate whether prenatal chronic stress, in combination with exposure to a developmental neurotoxicant, would increase effects in the offspring compared with the effects of either exposure alone. Development and neurobehavioral effects were investigated...... function due to CMS were observed. In the present experimental setting, there was no indication of the two exposures potentiating each other with respect to adverse effects on the nervous system. However, the effects of prenatal CMS indicate that stress during fetal life may interfere with the development...... in female offspring of pregnant rats (Mol:WIST) exposed to chronic mild stress (CMS) during gestational days (GD) 9-20, or 1500 ppm toluene, 6 h/day during gestational days 7-20, or a combination of the two. Prenatal CMS was associated with decreased thymic weight and increased auditory startle response...

  2. Effects of prenatal exposure to chronic mild stress and toluene in rats

    DEFF Research Database (Denmark)

    Hougaard, Karin; Andersen, Maibritt B; Hansen, Ase M

    2005-01-01

    The aim of the present study was to elucidate whether prenatal chronic stress, in combination with exposure to a developmental neurotoxicant, would increase effects in the offspring compared with the effects of either exposure alone. Development and neurobehavioral effects were investigated...... in female offspring of pregnant rats (Mol:WIST) exposed to chronic mild stress (CMS) during gestational days (GD) 9-20, or 1500 ppm toluene, 6 h/day during gestational days 7-20, or a combination of the two. Prenatal CMS was associated with decreased thymic weight and increased auditory startle response...... function due to CMS were observed. In the present experimental setting, there was no indication of the two exposures potentiating each other with respect to adverse effects on the nervous system. However, the effects of prenatal CMS indicate that stress during fetal life may interfere with the development...

  3. Study of substitution reactions of ligands in VO2+ complexes in toluene solutions by ESR method

    International Nuclear Information System (INIS)

    Lundkvist, R.; Panfilov, A.T.; Kalinichenko, N.B.; Marov, I.N.; AN SSSR, Moscow. Inst. Geokhimii i Analiticheskoj Khimii)

    1976-01-01

    Kinetics and equilibrium of stepwise substitution of ligands have been investigated at different temperatures for the complexes of oxovanadium (4) with salicylaldoxime, 8-oxyquinoline, acetylacetone, benzoylacetone, and tenoyltrifluoroacetone. The relative complexability of these ligands in toluene has been studied. The parameters of spin-Hamiltonian of EPR spectra of the VO 2+ complexes have been determined. The equilibrium constants, the rate constants, and activation energy have been found for the substitution reactions of ligands in the complexes VOA 2 : VOA 2 +HB=VOAB+HA; VOAB+HB=VOB 2 +HA, where HA and HB are the ligands with different donor atoms. The mixed complexes have been detected of the general formula VOAB, where HA is salicylaldoxime or 8-oxyquinoline and HB is β-diketone

  4. Determination of microquantities of methanol and ethanol in toluene by gas chromatography

    International Nuclear Information System (INIS)

    Perez, M. M.

    1970-01-01

    A study is made of the detection of methanol and ethanol in toluene by means of gas chromatography, using Porapak Q columns, 1 m long at 189 degree centigree, employing a flame ionization detector, with propanol as an internal standard. The variation od the detector absolute and relative response was found to be linear within the range of concentration studied, that is, from 5 to 1000 ppm. The limit of sensitivity for the detection of ethanol in a column of 2% Ucon, over Chromosorob G deactivated with 0,1% Carbowax 400, was 20 ppm, which was four times higher than the limit of sensitivity of the Porapak Q column. Also in this case, the absolute and relative response of the detector was linear. (Author) 3 refs

  5. Ultrathin Tungsten Oxide Nanowires/Reduced Graphene Oxide Composites for Toluene Sensing

    Directory of Open Access Journals (Sweden)

    Muhammad Hassan

    2017-09-01

    Full Text Available Graphene-based composites have gained great attention in the field of gas sensor fabrication due to their higher surface area with additional functional groups. Decorating one-dimensional (1D semiconductor nanomaterials on graphene also show potential benefits in gas sensing applications. Here we demonstrate the one-pot and low cost synthesis of W18O49 NWs/rGO composites with different amount of reduced graphene oxide (rGO which show excellent gas-sensing properties towards toluene and strong dependence on their chemical composition. As compared to pure W18O49 NWs, an improved gas sensing response (2.8 times higher was achieved in case of W18O49 NWs composite with 0.5 wt. % rGO. Promisingly, this strategy can be extended to prepare other nanowire based composites with excellent gas-sensing performance.

  6. 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...... 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...... fractionation (DC6D6/DC6H6 = 1.02), with a remarkably faster diffusion rate of the perdeuterated isotopologue that was enriched in the downgradient portion of the diffusion tubes and at the fringes of the contaminant plumes in the flow-through setup. These outcomes can neither be interpreted as mass...

  7. Volumetric properties under pressure for the binary system ethanol plus toluene

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Lugo, Luis; García, Josefa

    2005-01-01

    The density of the asymmetrical binary system composed of ethanol and toluene has been measured under pressure using a vibrating tube densimeter. The measurements have been performed for nine different compositions including the pure compounds at eight temperatures in the range 283.15–353.15 K...... and ten isobars up to 45 MPa. The uncertainty in the measured densities is estimated to be 0.1 kg m−3. The measured data has been used to study the behavior and influence of temperature, pressure and composition on the isothermal compressibility, the isobaric thermal expansion, and the excess molar volume....... At several temperatures the isobaric thermal expansion shows an non-monotonical behavior versus composition, whereas the excess molar volumes reveal a complex sigmoid behavior. These results have been interpreted as changes in the free-volume and as the formation and weakening of the molecular interactions...

  8. Endophytes and their Potential to Deal with Co-contamination of Organic Contaminants (Toluene) and Toxic Metals (Nickel) during Phytoremediation

    Energy Technology Data Exchange (ETDEWEB)

    Weyens, N.; van der Lelie, D.; Truyens, S.; Saenen, E.; Boulet, J.; Dupae, J.; Taghavi, S.; Carleer, R.; Vangronsveld, J.

    2011-01-15

    The aim was to investigate if engineered endophytes that are capable of degrading organic contaminants, and deal with or ideally improve uptake and translocation of toxic metals, can improve phytoremediation of mixed organic-metal pollution. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive toluene/TCE degradation, and (b) the chromosomally inserted ncc-nre Ni resistance/sequestration system. As controls, plants were inoculated with B. vietnamiensis BU61 (pTOM-Bu61) and B. cepacia BU72 (containing the ncc-nre Ni resistance/sequestration system). Plants were exposed to mixes of toluene and Ni. Only inoculation with B. cepacia VM1468 resulted in decreased Ni and toluene phytotoxicity, as measured by a protective effect on plant growth and decreased activities of enzymes involved in antioxidative defence (catalase, guaiacol peroxidase, superoxide dismutase) in the roots. Besides, plants inoculated with B. cepacia VM1468 and B. vietnamiensis BU61 released less toluene through the leaves than non-inoculated plants and those inoculated with B. cepacia BU72. Ni-uptake in roots was slightly increased for B. cepacia BU72 inoculated plants. These results indicate that engineered endophytes have the potential to assist their host plant to deal with co-contamination of toxic metals and organic contaminants during phytoremediation.

  9. Treatment of toluene and its by-products using an electron beam/ultra-fine bubble hybrid system

    Science.gov (United States)

    Son, Youn-Suk; Kim, Tae-Hun; Choi, Chang Yong; Park, Jun-Hyeong; Ahn, Ji-Won; Dinh, Trieu-Vuong

    2018-03-01

    Although, until quite recently, many technologies (electron beam (EB), plasma, and ultraviolet) have been studied to overcome disadvantages of conventional methods (such as absorption, adsorption, biofiltration and incineration) for treatment of volatile organic compounds (VOCs), their techniques still have some problems such as formation of a by-product. Generally, it is reported that various by-products are generated from the EB irradiation process to remove VOCs. Therefore, we developed an electron beam/ultra-fine bubble (EB/UB) hybrid system to enhance removal efficiency of a VOC (toluene) and to reduce its by-products formed by electron beam irradiation. As a result, the removal efficiency of toluene (30 ppm) by only EB (10 kGy) was 80.1%. However, the removal efficiency of toluene using the hybrid system (water temperature: 5 ℃) was increased up to 17% when compared to only EB (10 kGy). Additionally, the 65.2% of ozone formed from the EB process was removed in UB reactor. In case of other trace by-products such as undesired VOCs and aldehydes, the levels were lowered down to the below detection limit by the subsequent UB reactor. We also found that the amount of toluene collected and solubilized into water is affected by the water temperature in the UB reactor.

  10. Preliminary study to prepare a reference material of toluene metabolite - o-cresol and benzene metabolite-phenol - in human

    Czech Academy of Sciences Publication Activity Database

    Šperlingová, I.; Dabrowská, L.; Stránský, V.; Kučera, Jan; Tichý, M.

    2006-01-01

    Roč. 11, č. 5 (2006), s. 231-235 ISSN 0949-1775 R&D Projects: GA MZd NR7831 Institutional research plan: CEZ:AV0Z10480505 Keywords : reference material * toluene metabolites * o-cresol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.640, year: 2006

  11. AGING AND LIFE-STAGE SUSCEPTIBILITY: TOLUENE EFFECTS ON BRAIN OXIDATIVE STRESS PARAMETERS IN BROWN NORWAY RATS.

    Science.gov (United States)

    The influence of aging on susceptibility to environmental contaminants is poorly understood. The objectives of this study were to test whether oxidative stress (OS) is a potential toxicity pathway following toluene exposure and to determine if these effects are age-dependent. We ...

  12. Toluene effects on Oxidative Stress in Brain regions of Young-adult, Middleage,and Senescent Brown Norway Rats

    Science.gov (United States)

    The influence of aging on susceptibility to environmental contaminants is not well understood. To extend knowledge in this area, we examined effects in rat brain of the volatile organic compound toluene. The objective was to test whether oxidative stress plays a role in the adver...

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

    Science.gov (United States)

    Gholami, Mitra; Nassehinia, Hamid Reza; Jonidi-Jafari, Ahmad; Nasseri, Simin; Esrafili, Ali

    2014-02-05

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

  14. Acute Toluene Exposure Alters Expression of Genes in the Central Nervous System Associated With Synaptic Structure and Function

    Science.gov (United States)

    Toluene is a volatile organic compound (VOC) and a ubiquitous air pollutant of interest to EPA regulatory programs. Whereas its acute functional effects are well described, several modes of action in the CNS have been proposed. Therefore, we sought to identify potential pathways ...

  15. Theoretical Study of the Mechanism Behind the para-Selective Nitration of Toluene in Zeolite H-Beta

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Amity; Govind, Niranjan; Subramanian, Lalitha

    2011-11-28

    Periodic density functional theory calculations were performed to investigate the origin of the favorable para-selective nitration of toluene exhibited by zeolite H-beta with acetyl nitrate nitration agent. Energy calculations were performed for each of the 32 crystallographically unique Bronsted acid sites of a beta polymorph B zeolite unit cell with multiple Bronsted acid sites of comparable stability. However, one particular aluminum T-site with three favorable Bronsted site oxygens embedded in a straight 12-T channel wall provides multiple favorable proton transfer sites. Transition state searches around this aluminum site were performed to determine the barrier to reaction for both para and ortho nitration of toluene. A three-step process was assumed for the nitration of toluene with two organic intermediates: the pi- and sigma-complexes. The rate limiting step is the proton transfer from the sigma-complex to a zeolite Bronsted site. The barrier for this step in ortho nitration is shown to be nearly 2.5 times that in para nitration. This discrepancy appears to be due to steric constraints imposed by the curvature of the large 12-T pore channels of beta and the toluene methyl group in the ortho approach that are not present in the para approach.

  16. Palladium-Catalyzed Synthesis of Δ(2)-Isoxazoline from Toluene Derivatives Enabled by the Triple Role of Silver Nitrate.

    Science.gov (United States)

    Li, Chengliang; Deng, Hongmei; Li, Chunju; Jia, Xueshun; Li, Jian

    2015-11-20

    A palladium-catalyzed direct synthesis of Δ(2)-isoxazoline from toluene derivatives has been established. The present reaction proceeds through nondirected Csp(3)-H activation, benzylic nitration, dehydration, and cycloaddition. This protocol also features the unusual triple role of silver nitrate in a one-pot reaction.

  17. 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.

  18. Enhancing co-metabolic degradation of trichloroethylene with toluene using Burkholderia vietnamiensis G4 encapsulated in polyethylene glycol polymer.

    Science.gov (United States)

    Hamid, S; Bae, W; Kim, S; Amin, M T

    2014-01-01

    The biodegradation potential of Burkholderia vietnamiensis G4 (B. vietnamiensis G4) was evaluated under encapsulation in comparison with direct exposure to trichloroethylene (TCE) (0.1, 0.5, 1 and 5 mg/L) and toluene (10 and 50 mg/L), maintaining aerobic conditions. B. vietnamiensis G4 was encapsulated in polyethylene glycol (PEG) polymer. Under suspended conditions, the degradation rate decreased as the initial TCE concentration increased, even with a higher amount of substrate available. However, the encapsulated systems were less suppressed, presumably by mitigated toxicity, and completely removed TCE with 50 mg/L of toluene. The transformation yield (Ty) was as high as 0.427 mg-TCE/mg-toluene for the encapsulated cultures and 0.1007 mg-TCE/mg-toluene for the suspended cultures. The Ty value for the encapsulated cultures was one to two orders higher than what has been reported in the literature. The higher Ty values in the encapsulated cultures compared with those from suspended cultures showed that the PEG encapsulation provided more a favourable environment for efficient substrate use.

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

    Science.gov (United States)

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

    1991-01-01

    Seven different sources of inocula that included sediments, contaminated soils, groundwater, process effluent, and sludge were used to establish enrichment cultures of denitrifying bacteria on benzene, toluene, and xylenes in the absence of molecular oxygen. All of the enrichment cultures demonstrated complete depletion of toluene and partial depletion of o-xylene within 3 months of incubation. The depletion of o-xylene was correlated to and dependent on the metabolism of toluene. No losses of benzene, p-xylene, or m-xylene were observed in these initial enrichment cultures. However, m-xylene was degraded by a subculture that was incubated on m-xylene alone. Complete carbon, nitrogen, and electron balances were determined for the degradation of toluene and m-xylene. These balances showed that these compounds were mineralized with greater than 50% conversion to CO2 and significant assimilation into biomass. Additionally, the oxidation of these compounds was shown to be dependent on nitrate reduction and denitrification. These microbial degradative capabilities appear to be widespread, since the widely varied inoculum sources all yielded similar results. PMID:2014990

  20. UV spectra and kinetics of radicals produced in the gas phase reactions of Cl, F and OH with toluene

    DEFF Research Database (Denmark)

    Markert, F.; Pagsberg, P.

    1993-01-01

    The gas phase reactions of Cl, F and OH with toluene have been studied by pulse radiolysis combined with time-resolved UV spectroscopy. The formation of benzyl radicals via the abstraction reactions C6H5-CH3 + X --> C6H5-CH2 + HX was observed with X = Cl, F and OH. In the reaction with chlorine...

  1. Pervaporation of alcohol-toluene mixtures through polymer blend membranes of poly(acrylic acid) and poly(vinyl alcohol)

    NARCIS (Netherlands)

    Park, H.C.; Park, H.; Meertens, R.M.; Meertens, R.M.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

    1994-01-01

    Homogeneous membranes were prepared by blending poly(acrylic acid) with poly(vinyl alcohol). These blend membranes were evaluated for the selective separation of alcohols from toluene by pervaporation. The flux and selectivity of the membranes were determined both as a function of the blend

  2. A DYNAMIC PHYSIOLOGICALLY-BASED TOXICOKINETIC (DPBTK) MODEL FOR SIMULATION OF COMPLEX TOLUENE EXPOSURE SCENARIOS IN HUMANS

    Science.gov (United States)

    A GENERAL PHYSIOLOGICAL AND TOXICOKINETIC (GPAT) MODEL FOR SIMULATION OF COMPLEX TOLUENE EXPOSURE SCENARIOS IN HUMANS. E M Kenyon1, T Colemen2, C R Eklund1 and V A Benignus3. 1U.S. EPA, ORD, NHEERL, ETD, PKB, RTP, NC, USA; 2Biological Simulators, Inc., Jackson MS, USA, 3U.S. EP...

  3. U-Shaped Fiber-Optic Detection Elements for Investigation of Photocatalytic Decomposition of Toluene Dissolved in Water

    Czech Academy of Sciences Publication Activity Database

    Matějec, Vlastimil; Bartoň, Ivo; Mrázek, Jan; Podrazký, Ondřej

    2014-01-01

    Roč. 27, May (2014), s. 244-252 ISSN 2306-8515 R&D Projects: GA ČR GAP102/12/2361 Institutional support: RVO:67985882 Keywords : Toluene detection * Photocatalytic decomposition * U-Shaped fiber Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. Biodegradation of vapor-phase toluene in unsaturated porous media: Column experiments

    International Nuclear Information System (INIS)

    Khan, Ali M.; Wick, Lukas Y.; Harms, Hauke; Thullner, Martin

    2016-01-01

    Biodegradation of organic chemicals in the vapor phase of soils and vertical flow filters has gained attention as promising approach to clean up volatile organic compounds (VOC). The drivers of VOC biodegradation in unsaturated systems however still remain poorly understood. Here, we analyzed the processes controlling aerobic VOC biodegradation in a laboratory setup mimicking the unsaturated zone above a shallow aquifer. The setup allowed for diffusive vapor-phase transport and biodegradation of three VOC: non-deuterated and deuterated toluene as two compounds of highly differing biodegradability but (nearly) identical physical and chemical properties, and MTBE as (at the applied experimental conditions) non-biodegradable tracer and internal control. Our results showed for toluene an effective microbial degradation within centimeter VOC transport distances despite high gas-phase diffusivity. Degradation rates were controlled by the reactivity of the compounds while oxic conditions were found everywhere in the system. This confirms hypotheses that vadose zone biodegradation rates can be extremely high and are able to prevent the outgassing of VOC to the atmosphere within a centimeter range if compound properties and site conditions allow for sufficiently high degradation rates. - Highlights: • The column setup allows resolving vapor-phase VOC concentration gradients at cm scale resolution. • Vapor-phase and liquid-phase concentrations are measured simultaneously. • Isotopically labelled VOC was used as reference species of low biodegradability. • Biodegradation rates in the unsaturated zone can be very high and act at a cm scale. • Unsaturated material can be an effective bio-barrier avoiding biodegradable VOC emissions. - Microbial degradation activity can be sufficient to remove VOC from unsaturated porous media after a few centimeter of vapor-phase diffusive transport and mayeffectively avoid atmospheric emissions.

  5. Adsorption of benzene, toluene, and xylene by two tetramethylammonium-smectites having different charge densities

    Science.gov (United States)

    Lee, Jiunn-Fwu; Mortland, Max M.; Chiou, Cary T.; Kite, Daniel E.; Boyd, Stephen A.

    1990-01-01

    A high-charge smectite from Arizona [cation-exchange capacity (CEC) = 120 meq/100 g] and a low-charge smectite from Wyoming (CEC = 90 meq/100 g) were used to prepare homoionic tetramethylammonium (TMA)-clay complexes. The adsorption of benzene, toluene, and o-xylene as vapors by the dry TMA-clays and as solutes from water by the wet TMA-clays was studied. The adsorption of the organic vapors by the dry TMA-smectite samples was strong and apparently consisted of interactions with both the aluminosilicate mineral surfaces and the TMA exchange ions in the interlayers. In the adsorption of organic vapors, the closer packing of TMA ions in the dry high-charge TMA-smectite, compared with the dry low-charge TMA-smectite, resulted in a somewhat higher degree of shape-selective adsorption of benzene, toluene, and xylene. In the presence of water, the adsorption capacities of both samples for the aromatic compounds were significantly reduced, although the uptake of benzene from water by the low-charge TMA-smectite was still substantial. This lower sorption capacity was accompanied by increased shape-selectivity for the aromatic compounds. The reduction in uptake and increased selectivity was much more pronounced for the water-saturated, high-charge TMA-smectite than for the low-charge TMA-smectite. Hydration of the TMA exchange ions and/or the mineral surfaces apparently reduced the accessibility of the aromatic molecules to interlamellar regions. The resulting water-induced sieving effect was greater for the high-charge TMA-smectite due to the higher density of exchanged TMA-ions. The low-charge Wyoming TMA-smectite was a highly effective adsorbent for removing benzene from water and may be useful for purifying benzene-contaminated water.

  6. Viscosity of heptane-toluene mixtures. Comparison of molecular dynamics and group contribution methods.

    Science.gov (United States)

    Velásquez, Ana Milena; Hoyos, Bibian A

    2017-02-01

    Three methods of molecular dynamics simulation [Green-Kubo (G-K), non-equilibrium molecular dynamics (NEMD) and reversed non-equilibrium molecular dynamics (RNEMD)], and two group contribution methods [UNIFAC-VISCO and Grunberg-Nissan (G-N)] were used to calculate the viscosity of mixtures of n-heptane and toluene (known as heptol). The results obtained for the viscosity and density of heptol were compared with reported experimental data, and the advantages and disadvantages of each method are discussed. Overall, the five methods showed good agreement between calculated and experimental viscosities. In all cases, the deviation was lower than 9%. It was found that, as the concentration of toluene increases, the deviation of the density of the mixture (as calculated with molecular dynamics methods) also increases, which directly affects the viscosity result obtained. Among the molecular simulation techniques evaluated here, G-K produced the best results, and represents the optimal balance between quality of result and time required for simulation. The NEMD method produced acceptable results for the viscosity of the system but required more simulation time as well as the determination of an appropriate shear rate. The RNEMD method was fast and eliminated the need to determine a set of values for shear rate, but introduced large fluctuations in measurements of shear rate and viscosity. The two group contribution methods were accurate and fast when used to calculate viscosity, but require knowledge of the viscosity of the pure compounds, which is a serious limitation for applications in complex multicomponent systems.

  7. Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

    Science.gov (United States)

    Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

    2014-08-01

    The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

  8. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion

    Energy Technology Data Exchange (ETDEWEB)

    Pozan, Gulin Selda, E-mail: gpozan@istanbul.edu.tr [Istanbul University, Faculty of Engineering, Chemical Engineering Department, Avcilar 34320, Istanbul (Turkey)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer {alpha}-Al{sub 2}O{sub 3}, obtained from Bohmite, as a support for enhancing of the activity. Black-Right-Pointing-Pointer The support material for catalytic oxidation. Black-Right-Pointing-Pointer The manganese state and oxygen species effect on the catalytic combustion reaction. - Abstract: The aim of this work was to study combustion of toluene (1000 ppm) over MnO{sub 2} modified with different supports. {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3} obtained from Boehmite, {gamma}-Al{sub 2}O{sub 3} (commercial), SiO{sub 2}, TiO{sub 2} and ZrO{sub 2} were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO{sub 2} was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO{sub 2}/{alpha}-Al{sub 2}O{sub 3}(B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289 Degree-Sign C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity.

  9. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion

    International Nuclear Information System (INIS)

    Pozan, Gulin Selda

    2012-01-01

    Highlights: ► α-Al 2 O 3 , obtained from Bohmite, as a support for enhancing of the activity. ► The support material for catalytic oxidation. ► The manganese state and oxygen species effect on the catalytic combustion reaction. - Abstract: The aim of this work was to study combustion of toluene (1000 ppm) over MnO 2 modified with different supports. α-Al 2 O 3 and γ-Al 2 O 3 obtained from Boehmite, γ-Al 2 O 3 (commercial), SiO 2 , TiO 2 and ZrO 2 were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO 2 was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO 2 /α-Al 2 O 3 (B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289 °C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity.

  10. Studies on cytogenetic effects induced by chronic γ-radiation combined with benzene, toluene and carbon monoxide inhalation in animals

    International Nuclear Information System (INIS)

    Zhang Hongyuan; Wang Yuexing; Wang Lanjin; Pan Yan

    1998-01-01

    8 experimental groups were conducted according to four factors two doses orthogonal layout [L8(2 7 )] in present investigation. 90 healthy male rabbits and 90 healthy male mice were equally divided into 8 experimental groups and control group. Exprimental animals were exposed to γ-radiation combined with benzene, toluene and CO vapour for 2h per day, 5 days per week for 8 weeks. Two doses of γ-radiation, benzene, toluene and CO were 0.0375 and 0.0075 Gy/d (for rabbits, 0.0473 and 0.0095 Gy/d for mice), 182 +- 33 and 40 +- 15 mg/m 3 , 407 +- 68 and 90 +- 39 mg/m 3 as well as 278 +- 18 mg/m 3 , respectively. The main results were showed as follows: (1) γ-radiation, benzene and toluene could all induce chromosome aberration, SCEs and micronuclei of lymphocytes in rabbits and chromosome aberrations of bone marrow cells in rabbits and mice, but those was no observed in carbon monoxide. (2) γ-radiation and benzene induced chromosome aberrations and micronuclei of lymphocytes in rabbits as well as chromosome aberrations of bone marrow cells in mice, γ-radiation and toluene induced chromosome aberrations of lymphocytes (in rabbits) and bone marrow cells (in mice), benzene and toluene induced chromosome aberrations of lymphocytes (in rabbits) and bone marrow cells (in mice). They showed all significantly interaction. (3) In combined effects, the yield of chromosome aberrations, SCEs and micronuclei induced by (1) experimental groups which four factors are all high doses were highest, however, those by induced (8) experimental groups which four factors are all low doses also were higher than those of control group and there were statistical difference except SCEs

  11. Theoretical Study of the Mechanism Behind the para-Selective Nitration of Toluene in Zeolite H-Beta

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Amity; Govind, Niri; Subramanian, Lalitha

    2008-10-24

    In this work, we investigate the origin of the favorable para-selective nitration of toluene exhibited by H- beta zeolite solid acid catalyst. Periodic density functional theory calculations were performed to study the toluene nitration by acetyl nitrate within the pore system of a model H-beta structure. Firstly, energetics were calculated for each of the 32 crystallographically unique Br¿nsted acid sites of a beta polymorph B zeolite unit cell. These calculations revealed more than one favorable Br¿nsted acid site. However, steric and mechanistic considerations could be used to argue that one particular aluminum site with three favorable Br¿nsted site oxygens comprising a 12-T pore wall would be a likely site for nitration to take place. Transition state searches around this aluminum site were performed to determine the barrier to reaction for both para and ortho nitration of the toluene. A three-step process was assumed for the nitration of toluene with two organic intermediates: the ¼-complex and the ¾-complex (i.e., Wheland or arenium complex). The rate limiting step of the three-step process is the transfer of the proton from the ¾-complex to a Br¿nsted site on the zeolite cage. The barrier for this step in the ortho nitration case is shown to be nearly 2.5 times that for the para nitration case. The reason for the discrepancy appears to be a subtle steric constraint imposed by the curvature of the 12-T pore system of the beta zeolite and the methyl group of the toluene in the case of the ortho approach.

  12. Theoretical Study of the Mechanism Behind the para-Selective Nitration of Toluene in Zeolite H-Beta

    International Nuclear Information System (INIS)

    Andersen, Amity; Govind, Niri; Subramanian, Lalitha

    2008-01-01

    In this work, we investigate the origin of the favorable para-selective nitration of toluene exhibited by H- beta zeolite solid acid catalyst. Periodic density functional theory calculations were performed to study the toluene nitration by acetyl nitrate within the pore system of a model H-beta structure. Firstly, energetics were calculated for each of the 32 crystallographically unique Broensted acid sites of a beta polymorph B zeolite unit cell. These calculations revealed more than one favorable Broensted acid site. However, steric and mechanistic considerations could be used to argue that one particular aluminum site with three favorable Broensted site oxygens comprising a 12-T pore wall would be a likely site for nitration to take place. Transition state searches around this aluminum site were performed to determine the barrier to reaction for both para and ortho nitration of the toluene. A three-step process was assumed for the nitration of toluene with two organic intermediates: the π-complex and the σ-complex (i.e., Wheland or arenium complex). The rate limiting step of the three-step process is the transfer of the proton from the σ-complex to a Broensted site on the zeolite cage. The barrier for this step in the ortho nitration case is shown to be nearly 2.5 times that for the para nitration case. The reason for the discrepancy appears to be a subtle steric constraint imposed by the curvature of the 12-T pore system of the beta zeolite and the methyl group of the toluene in the case of the ortho approach

  13. Low-temperature abatement of toluene over Mn-Ce oxides catalysts synthesized by a modified hydrothermal approach

    Science.gov (United States)

    Du, Jinpeng; Qu, Zhenping; Dong, Cui; Song, Lixin; Qin, Yuan; Huang, Na

    2018-03-01

    Mn-Ce oxides catalysts were synthesized by a novel method combining redox-precipitation and hydrothermal approach. The results indicate that the ratio between manganese and cerium plays a crucial role in the formation of catalysts, and the textual properties as well as catalytic activity are remarked affected. Mn0.6Ce0.4O2 possesses a predominant catalytic activity in the oxidation of toluene, over 70% of toluene is converted at 200 °C, and the complete conversion temperature is 210 °C. The formation of Mn-Ce solid solution markedly improves the surface area as well as pore volume of Mn-Ce oxide catalyst, and Mn0.6Ce0.4O2 possesses the largest surface area of 298.5 m2/g. The abundant Ce3+ and Mn3+ on Mn0.6Ce0.4O2 catalyst facilitate the formation of oxygen vacancies, and improve the transfer of oxygen in the catalysts. Meanwhile, it is found that cerium in Mn-Ce oxide plays a key role in the adsorption of toluene, while manganese is proved to be crucial in the oxidation of toluene, the cooperation between manganese and cerium improves the catalytic reaction process. In addition, the reaction process is investigated by in situ DRIFT measurement, and it is found that the adsorbed toluene could be oxidized to benzyl alcohol as temperature rises around 80-120 °C that can be further be oxidized to benzoic acid. Then benzoic acid could be decomposed to formate and/or carbonate species as temperature rises to form CO2 and H2O. In addition, the formed by-product phenol could be further oxidized into CO2 and H2O when the temperature is high enough.

  14. Investigation of gasoline distributions within petrol stations: spatial and seasonal concentrations, sources, mitigation measures, and occupationally exposed symptoms.

    Science.gov (United States)

    Sairat, Theerapong; Homwuttiwong, Sahalaph; Homwutthiwong, Kritsana; Ongwandee, Maneerat

    2015-09-01

    We measured levels of VOCs and determined the distributions of benzene concentrations over the area of two petrol stations in all three seasons. Using the concentrations and sampling positions, we created isoconcentration contour maps. The average concentrations ranged 18-1288 μg m(-3) for benzene and 12-81 μg m(-3) for toluene. The contour maps indicate that high-level contours of benzene were found not only at the fuel dispenser areas but also at the storage tank refilling points, open drainage areas where gasoline-polluted wastewater was flowing, and the auto service center located within the station area. An assessment of the benzene to toluene ratio contour plots implicates that airborne benzene and toluene near the fuel dispenser area were attributed to gasoline evaporation although one of the studied stations may be influenced by other VOC sources besides gasoline evaporation. Additionally, during the routine refilling of the underground fuel storage tanks by a tank truck, the ambient levels of benzene and toluene increased tremendously. The implementation of source control by replacing old dispensers with new fuel dispensers that have an efficient cutoff feature and increased delivery speed can reduce spatial benzene concentrations by 77%. Furthermore, a questionnaire survey among 63 service attendants in ten stations revealed that headache was the most reported health complaint with a response rate of 32%, followed by fatigue with 20%. These prominent symptoms could be related to an exposure to high benzene concentrations.

  15. Pulmonary fibrotic response to inhalation of ZnO nanoparticles and toluene co-exposure through directed flow nose only exposure chamber.

    Science.gov (United States)

    Jain, Sonam; Rachamalla, Mahesh; Kulkarni, Apoorva; Kaur, Jasmine; Tikoo, Kulbhushan

    2013-11-01

    The increasing use of Zinc Oxide nanoparticles (ZnONPs) in paint industry is not supplemented with adequate toxicology data. This report focuses on the fibrogenic toxicity caused due to co-exposure of ZnONPs and toluene in male Wistar rats, exposed for 28 days, through directed flow nose only exposure chamber. The rats were grouped as air control, toluene control (200 ppm), zinc oxide control (10 mg/m(3)), low dose co-exposed (5 mg/m(3) ZnO and 200 ppm of toluene) and high dose co-exposed (10 mg/m(3) of ZnO and 200 ppm of toluene). Our study demonstrates that co-exposure of ZnONPs and toluene (as in paint industry), even at their respective permissible exposure level (5 mg/m(3) for ZnO and 200 ppm for toluene) have the potential to produce a progressive inflammatory and fibrotic response in the alveolar tissues of the lungs. We observed a significant increase in inflammatory markers in BAL fluid and elevated malondialdehyde (MDA) levels with lower levels of intracellular reduced glutathione (GSH) in lungs of rats of co-exposed group. Significant increase in the levels of pro-inflammatory mediators (IL-6, Ikβα, Cox-II, p-NF-κB) in lung tissues also indicated pulmonary damage. To best of our knowledge this is the first study which highlights the toxicity of co-exposed ZnO NPs and toluene.

  16. Changes in the chemical properties and swelling coefficient of alfalfa root cell walls in the presence of toluene as a toxic agent.

    Science.gov (United States)

    Sharifi, M; Khoshgoftarmanesh, A H; Hadadzadeh, H

    2016-04-01

    The influence of toluene pollution on the chemical properties and swelling coefficient of root cell walls in alfalfa (Medicago sativa L.) was investigated. Two sets of alfalfa seedlings were selected and one set was treated with 450 mg L(-1) toluene in the nutrient solution under hydroponic culture. Thirty days after treatment with toluene, alfalfa plants were harvested and the root cell walls were isolated. Fourier-transform infrared (FTIR) spectroscopy was carried out for the characterization of the root cell walls composition. The cation exchange capacity (CEC) and the swelling coefficient of the root cell walls (Kcw) were estimated at various pH values. The toluene contamination significantly reduced the mass of the cell wall material in the alfalfa roots. According to the FTIR spectra, the toluene pollution can change the alfalfa root cell wall properties by reducing the cell wall functional groups. These functional groups are probably related to the proteins and polysaccharides in the cell wall. Also, toluene pollution strongly reduced CEC and Kcw of the root cell walls. The results show that the decrease in the active sites of adsorption on the root cell walls as a response to toluene pollution can affect the water flow rate and the mineral nutrients uptake by roots.

  17. Isolation and characterization of Magnetospirillum sp. strain 15-1 as a representative anaerobic toluene-degrader from a constructed wetland model.

    Directory of Open Access Journals (Sweden)

    Ingrid Meyer-Cifuentes

    Full Text Available Previously, Planted Fixed-Bed Reactors (PFRs have been used to investigate microbial toluene removal in the rhizosphere of constructed wetlands. Aerobic toluene degradation was predominant in these model systems although bulk redox conditions were hypoxic to anoxic. However, culture-independent approaches indicated also that microbes capable of anaerobic toluene degradation were abundant. Therefore, we aimed at isolating anaerobic-toluene degraders from one of these PFRs. From the obtained colonies which consisted of spirilli-shaped bacteria, a strain designated 15-1 was selected for further investigations. Analysis of its 16S rRNA gene revealed greatest similarity (99% with toluene-degrading Magnetospirillum sp. TS-6. Isolate 15-1 grew with up to 0.5 mM of toluene under nitrate-reducing conditions. Cells reacted to higher concentrations of toluene by an increase in the degree of saturation of their membrane fatty acids. Strain 15-1 contained key genes for the anaerobic degradation of toluene via benzylsuccinate and subsequently the benzoyl-CoA pathway, namely bssA, encoding for the alpha subunit of benzylsuccinate synthase, bcrC for subunit C of benzoyl-CoA reductase and bamA for 6-oxocyclohex-1-ene-1-carbonyl-CoA hydrolase. Finally, most members of a clone library of bssA generated from the PFR had highest similarity to bssA from strain 15-1. Our study provides insights about the physiological capacities of a strain of Magnetospirillum isolated from a planted system where active rhizoremediation of toluene is taking place.

  18. Synergetic effect between adsorption and photodegradation on nanostructured TiO{sub 2}/activated carbon fiber felt porous composites for toluene removal

    Energy Technology Data Exchange (ETDEWEB)

    Li, Min; Lu, Bin; Ke, Qin-Fei; Guo, Ya-Jun; Guo, Ya-Ping, E-mail: ypguo@shnu.edu.cn

    2017-07-05

    Highlights: • Nanostructured TiO{sub 2}/activated carbon fiber felt porous composites are prepared. • Nanostructures TiO{sub 2} particles on fibers are constructed by nanocrystals. • They have synergetic adsorption-photocatalytic activities for toluene removal. • The adsorption efficiency reaches 98% at toluene concentrations <1150 ppm. • Carbon fibers can hinder the recombination of electron-hole pairs on TiO{sub 2}. - Abstract: The low quantum efficiency and limited adsorption efficiency of TiO{sub 2} makes it only fit for the removal of VOCs with low concentrations. Herein, we for the first time fabricated nanostructured TiO{sub 2}/activated carbon fiber felt (TiO{sub 2}/ACFF) porous composites by the in situ deposition of TiO{sub 2} microspheres on the carbon fibers in ACFF. Interestingly, the TiO{sub 2} microspheres exhibit hierarchical nanostructures constructed by nanocrystals as building blocks. The TiO{sub 2}/ACFF porous composites possess excellent adsorption and photodegradation properties for toluene because of the synergetic effects between the nanostructured TiO{sub 2} and ACFF. The adsorption efficiencies of the TiO{sub 2}/ACFF porous composites reach approximately 98% at the toluene concentration (<1150 ppm) and approximately 77% even at the high concentration of 6900 ppm. Moreover, the ACFF in the TiO{sub 2}/ACFF porous composites significantly enhances photocatalytic property for toluene by hindering the recombination of electron-hole pairs, reducing the TiO{sub 2} band gap energy (E{sub g}) to 2.95 eV and accelerating toluene adsorption. At the toluene concentrations of 230 ppm and 460 ppm, the photocatalytic oxidation efficiency of toluene into CO{sub 2} arrives at 100% and 81.5%, respectively. Therefore, the TiO{sub 2}/ACFF porous composites with synergetic adsorption and photocatalytic activities have great potentials for toluene removal.

  19. Volumetric behaviour of binary liquid systems composed of toluene, isooctane, and methyl tert-butyl ether at temperatures from (298.15 to 328.15) K

    International Nuclear Information System (INIS)

    Moravkova, L.; Wagner, Z.; Linek, J.

    2009-01-01

    The densities and speeds of sound of (toluene + isooctane), (MTBE + toluene), and (MTBE + isooctane) were measured at four temperatures from (298.15 to 328.15) K, and the respective values of excess volumes V m E and adiabatic compressibility κ S were calculated. The V m E and κ S values were fitted to the fourth-order Redlich-Kister equation. The V m E values for (MTBE + toluene) are negative and decreasing with increasing temperature. The other systems show positive V m E with comparatively small temperature dependence

  20. 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.)

  1. Application of Glycyrrhiza glabra Root as a Novel Adsorbent in the Removal of Toluene Vapors: Equilibrium, Kinetic, and Thermodynamic Study

    Directory of Open Access Journals (Sweden)

    Fazel Mohammadi-Moghadam

    2013-01-01

    Full Text Available The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R isotherm also showed that the sorption by GGR was physical in nature. The results of the thermodynamic analysis illustrated that the adsorption process is exothermic. GGR as a novel adsorbent has not previously been used for the adsorption of pollutants.

  2. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  3. Conversion of toluene and water to methylcyclohexane and oxygen using niobium-doped strontium titanate photoelectrodes.

    Science.gov (United States)

    Kalousek, Vit; Wang, Peng; Minegishi, Tsutomu; Hisatomi, Takashi; Nakagawa, Kojiro; Oshima, Shinji; Kobori, Yoshihiro; Kubota, Jun; Domen, Kazunari

    2014-09-01

    Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be harnessed as an alternate fuel source, which paves the way to a clean-energy future. A photoelectrochemical (PEC) system with a Nb:SrTiO3 photoelectrode for oxygen evolution from an aqueous electrolyte and a Pt/C electrode for toluene (TL) hydrogenation to MCH was investigated under UV irradiation. A Nb:SrTiO3 single-crystal electrode and an ionomer/Pt/C membrane-electrode assembly (MEA) were used as the photoanode and cathode, respectively. A steady-state current density of 0.12 mA cm(-2) was observed for the two-electrode system without any bias voltage for >2 h, and a Faradaic efficiency of 97% was obtained for MCH production from TL. This is the first demonstration of the production of MCH from TL and water using only light energy. This means that light energy was converted directly into MCH from TL and water without any electricity. The PEC properties of the devices are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. An in-situ FTIR study of the side-chain alkylation of toluene with methanol

    International Nuclear Information System (INIS)

    King, S.T.; Garces, J.

    1985-01-01

    The side-chain alkylation of toluene with methanol to styrene and ethylbenzene can be an economically attractive industrial process if it has high enough conversion and selectivity. This process has been investigated by many others using zeolites or metal oxides as the catalyst. It has been generally accepted that high basicity in certain size pores in the catalyst is required for such side-chain alkylation. However, the actual reaction mechanism is still not understood. In this paper the results of an in-situ FT-IR study of the side-chain alkylation in Li, Na, K, Rb and Cs exchanged X zeolites is discussed. It was found that the KX, RbX and CsX zeolites, which are capable of side-chain alkylation, also form surface formate and a surface precursor of formate from methanol decomposition. While the surface formate itself is not the alkylation agent, the observed formate precursor may be the intermediate for side-chain alkylation

  5. Modeling energy transfer in molecular collisions: Statistical theory versus experiment for highly excited toluene and azulene

    Science.gov (United States)

    Nilsson, Daniel; Nordholm, Sture

    2003-12-01

    The recent development and application of the method of kinetically controlled selective ionization has produced detailed and reliable data on the collisional energy transfer kernel P(E',E) entering master equation theories of unimolecular reaction rates. Here we test the ability of our partially ergodic collision theory (PECT) to predict the functional form of the observed kernel leaving only one parameter, the first moment of the distribution , to be input from other sources. The data explored here include two reactant molecules, toluene and azulene, in collisions with 18 and 8 medium molecules, respectively, ranging from inert gas atoms to n-heptane. The initial energy of the reactant molecule is varied from 10 000 cm-1 to 49 000 cm-1 and 30 000 cm-1, respectively. The energy transfer efficiency βE is about one-tenth of its ergodic collision limit of unity. The PECT is found to fit the monoexponential form of the kernel determined from the experimental data over a broad range of initial energies E including tail regions of very low probability. A minor but systematic deviation is observed for nearly elastic collisions of large medium molecules. The functional fit is good enough to effectively allow the three parameters of the monoexponential experimental kernel to be replaced by a single parameter representing energy transfer efficiency.

  6. Mutual diffusion of binary liquid mixtures containing methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride

    Energy Technology Data Exchange (ETDEWEB)

    Guevara-Carrion, Gabriela; Janzen, Tatjana; Muñoz-Muñoz, Y. Mauricio; Vrabec, Jadran, E-mail: jadran.vrabec@uni-paderborn.de [Thermodynamics and Energy Technology, University of Paderborn, 33098 Paderborn (Germany)

    2016-03-28

    Mutual diffusion coefficients of all 20 binary liquid mixtures that can be formed out of methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride without a miscibility gap are studied at ambient conditions of temperature and pressure in the entire composition range. The considered mixtures show a varying mixing behavior from almost ideal to strongly non-ideal. Predictive molecular dynamics simulations employing the Green-Kubo formalism are carried out. Radial distribution functions are analyzed to gain an understanding of the liquid structure influencing the diffusion processes. It is shown that cluster formation in mixtures containing one alcoholic component has a significant impact on the diffusion process. The estimation of the thermodynamic factor from experimental vapor-liquid equilibrium data is investigated, considering three excess Gibbs energy models, i.e., Wilson, NRTL, and UNIQUAC. It is found that the Wilson model yields the thermodynamic factor that best suits the simulation results for the prediction of the Fick diffusion coefficient. Four semi-empirical methods for the prediction of the self-diffusion coefficients and nine predictive equations for the Fick diffusion coefficient are assessed and it is found that methods based on local composition models are more reliable. Finally, the shear viscosity and thermal conductivity are predicted and in most cases favorably compared with experimental literature values.

  7. The time-resolved photoelectron spectrum of toluene using a perturbation theory approach

    Energy Technology Data Exchange (ETDEWEB)

    Richings, Gareth W.; Worth, Graham A., E-mail: g.a.worth@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom)

    2014-12-28

    A theoretical study of the intra-molecular vibrational-energy redistribution of toluene using time-resolved photo-electron spectra calculated using nuclear quantum dynamics and a simple, two-mode model is presented. Calculations have been carried out using the multi-configuration time-dependent Hartree method, using three levels of approximation for the calculation of the spectra. The first is a full quantum dynamics simulation with a discretisation of the continuum wavefunction of the ejected electron, whilst the second uses first-order perturbation theory to calculate the wavefunction of the ion. Both methods rely on the explicit inclusion of both the pump and probe laser pulses. The third method includes only the pump pulse and generates the photo-electron spectrum by projection of the pumped wavepacket onto the ion potential energy surface, followed by evaluation of the Fourier transform of the autocorrelation function of the subsequently propagated wavepacket. The calculations performed have been used to study the periodic population flow between the 6a and 10b16b modes in the S{sub 1} excited state, and compared to recent experimental data. We obtain results in excellent agreement with the experiment and note the efficiency of the perturbation method.

  8. Prilling and Coating of Ammonium Dinitramide (ADN Solid Green Propellant in Toluene Mixture Using Ultrasound Sonication

    Directory of Open Access Journals (Sweden)

    Asad Rahman

    2018-03-01

    Full Text Available Ammonium Dinitramide (ADN in its generic form has a long needle shaped structure, which hinders higher solid loading. Therefore, it is of utmost importance to optimize its crystal morphology into octagonal shapes. Moreover, the low critical humidity level of ADN renders it unusable in a humid climate. Hence, encapsulation with a hydrophobic polymer is necessary. In the present work, ADN was synthesized by nitration of potassium sulfamate with mixed acid nitration. The product was then mixed with toluene, graphene, citryl ammonium butyl, Cab-o-sil, and coating polymer (Polystyrene or HTPB and treated with ultrasound to obtain semi-spherical ADN-coated particles. The method offers a reduction in operating temperature and elimination of ADN melting in the shape-altering process. In addition, the ADN product has a similar particle size and thermal stability compared to those in a conventional ADN melt-prilling method. The ADN product investigated under SEM confirms the particle morphological change from long needles into semi-spherical shapes. The particle size obtained, in the micrometer range, is ideal for higher theoretical maximum density. Furthermore, the ultrasound-treated ADN particles show significant reduction in moisture absorption, from 68% to 16% at 65% relative humidity. The DSC result shows no degradation of thermal stability of the coated particles.

  9. Extraction of lanthanide(3) and Y(3) nitrates with trialkyl benzylammonium nitrate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Zhikharev, D.A.; Keskinov, V.A.

    2003-01-01

    Extraction of lanthanides(3) [Ln=La-Nd, Sm-Lu] and Y(3) from 0.55 mol/l toluene solutions with trialkyl benzylammonium nitrate (TABAN) was studied at 298 K. The extraction isotherms were analyzed in the assumption of formation of the following complexes: (R 4 N) 3 [Ln(NO 3 ) 6 ] and (R 4 N) 4 [Ln(NO 3 ) 7 ] for La(3) and Ce(3); (R 4 N) 2 [Ln(NO 3 ) 5 ] and (R 4 N) 3 [Ln(NO 3 ) 6 ] for Pr(3)-Gd(3); (R 4 N) 2 [Ln(NO 3 ) 5 ] for Tb(3)-Lu(3) and Y(3) in the organic phase. The values of the extraction constants decreasing in the series La(3)-Lu(3) were calculated. The extraction constants of Y(3) and Yb(3) are similar. The TABAN concentration in the organic phase does not noticeably influence the composition of the extractable complexes and the extraction constants [ru

  10. Mesoporous single-crystal Cr 2O 3: Synthesis, characterization, and its activity in toluene removal

    Science.gov (United States)

    Wang, Yangang; Yuan, Xiaohong; Liu, Xiaohui; Ren, Jiawen; Tong, Weiyi; Wang, Yanqin; Lu, Guanzhong

    2008-09-01

    In this paper, a series of ordered mesoporous single-crystal Cr 2O 3 samples were synthesized through a hard-templating pathway by using three-dimensional (3D) cubic mesoporous silica, KIT-6, as the template and chromium nitrate as the precursor. In the synthesis, the intermediate composites (chromium nitrate/KIT-6) were calcined in air for 4 h at different temperatures (from 400 to 700 °C, interval 100 °C) to decompose the nitrate species. Then, the silica template was removed by dissolution in 10% HF solution twice. The resulting Cr 2O 3 samples were characterized by XRD, TEM, XPS, and N 2-sorption analysis and their catalytic properties were also investigated in the oxidation of toluene. These results showed that the obtained ordered mesoporous Cr 2O 3 are exact reverse-replica of the template. It was also found that the catalytic activity was related to mesostructure and/or surface area as well as the calcination temperatures.

  11. Rapid microbial mineralization of toluene and 1,3-dimethylbenzene in the absence of molecular oxygen

    International Nuclear Information System (INIS)

    Zeyer, J.; Kuhn, E.P.; Schwarzenbach, R.P.

    1986-01-01

    Up to 0.4 mM 1,3-dimethylbenzene (m-xylene) was rapidly mineralized in a laboratory aquifer column operated in the absence of molecular oxygen with nitrate as an electron acceptor. Under continuous flow conditions, the degradation rate constant (pseudo-first order) was >0.45 h -1 . Based on a carbon mass balance with [ring- 14 C]m-xylene and a calculation of the electron balance, m-xylene was shown to be quantitatively (80%) oxidized to CO 2 with a concomitant reduction of nitrate. The mineralization of m-xylene in the column also took place after reducing the redox potential, E', of the inflowing medium with sulfide to <-0.11 V. Microorganisms adapted to growth on m-xylene were also able to degrade toluene under denitrifying conditions. These results suggest that aromatic hydrocarbons present in anoxic environments such as lake sediments, sludge digestors, and ground water infiltration zones from landfills and polluted rivers are not necessarily persistent but may be mineralized in the absence of molecular oxygen

  12. Degree of Branching in Hyperbranched Poly(glycerol-co-diacids Synthesized in Toluene

    Directory of Open Access Journals (Sweden)

    Gary D. Strahan

    2012-02-01

    Full Text Available 1H NMR and 13C NMR spectrometry (1-dimensional and 2-dimensional have been used to assign chemical resonances and determine the degrees of branching for polyesters synthesized by the Lewis acid (dibutyltin(IVoxide-catalyzed polycondensation of glycerol with either succinic acid (n (aliphatic chain length = 2, glutaric acid (n = 3 or azelaic acid (n = 7 in quasi-melt solutions with toluene. When 1:1 and 2:1 (diacid:glycerol molar ratios were used, it was found that the glutaric acid-derived polymers gave the highest degree of polymer branching (31.2%, 85.6%, respectively after the 24 h reaction period followed by the succinic acid-derived polymers (39.4%, 41.9%, respectively and the azelaic acid-derived polymers (9.9%, 13.9%, respectively. Reactions performed at reflux for 24 h resulted in a 70.8% and 56.7% decrease in degree of branching for succinic acid and glutaric acid-derived polyesters, respectively. There is no indication that degree of branching is significantly affected by the presence or absence of solvent according to the results obtained in this research.

  13. Nanosized metal deposits on titanium dioxide for augmenting gas-phase toluene photooxidation

    Science.gov (United States)

    Lee, Sooi Li; Scott, Jason; Chiang, Ken; Amal, Rose

    2009-01-01

    The build-up of intermediate species on the surface of TiO2 during gas-phase toluene (C7H8) photodegradation has been observed to deactivate the photocatalyst. Nanosized metallic deposits on the TiO2 surface may enhance the photocatalytic process and improve photocatalyst performance. In this study, noble (Ag, Au) and platinum group (Pt, Pd, Rh) metals, at a nominal loading of 0.5 at.%, were deposited onto Degussa P25 TiO2 to enhance photocatalyst performance and inhibit deactivation. Pd, Rh and Au deposits delayed photocatalyst deactivation by a factor of 2, while Pt deposits delayed photocatalyst deactivation by a factor of 20, when compared with neat TiO2. Ag deposits did not improve photocatalyst activity. Metal deposit performance was related to the work function of each metal, however, the Pt finding suggested that these effects are not governed solely by this aspect, but factors such as deposit characteristics and/or thermal catalytic properties of the metals may be influential.

  14. Risk assessment for consumer exposure to toluene diisocyanate (TDI) derived from polyurethane flexible foam.

    Science.gov (United States)

    Arnold, Scott M; Collins, Michael A; Graham, Cynthia; Jolly, Athena T; Parod, Ralph J; Poole, Alan; Schupp, Thomas; Shiotsuka, Ronald N; Woolhiser, Michael R

    2012-12-01

    Polyurethanes (PU) are polymers made from diisocyanates and polyols for a variety of consumer products. It has been suggested that PU foam may contain trace amounts of residual toluene diisocyanate (TDI) monomers and present a health risk. To address this concern, the exposure scenario and health risks posed by sleeping on a PU foam mattress were evaluated. Toxicity benchmarks for key non-cancer endpoints (i.e., irritation, sensitization, respiratory tract effects) were determined by dividing points of departure by uncertainty factors. The cancer benchmark was derived using the USEPA Benchmark Dose Software. Results of previous migration and emission data of TDI from PU foam were combined with conservative exposure factors to calculate upper-bound dermal and inhalation exposures to TDI as well as a lifetime average daily dose to TDI from dermal exposure. For each non-cancer endpoint, the toxicity benchmark was divided by the calculated exposure to determine the margin of safety (MOS), which ranged from 200 (respiratory tract) to 3×10(6) (irritation). Although available data indicate TDI is not carcinogenic, a theoretical excess cancer risk (1×10(-7)) was calculated. We conclude from this assessment that sleeping on a PU foam mattress does not pose TDI-related health risks to consumers. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Preparation and characterization of starch grafted with toluene poly (propylene oxide diisocyanate

    Directory of Open Access Journals (Sweden)

    D.C. Dragunski

    2001-01-01

    Full Text Available Amylopectin-rich starch samples (Amidex 4001 Corn Products Brasil Ingredientes Industriais Ltda. were grafted with polyethers with the purpose of obtaining new materials for application as solid polymeric electrolytes. Grafting reaction was performed by the addition of starch dissolved in DMSO to toluene poly(propylene oxide diisocyanate (Resibras dissolved in the same solvent. This reaction produced a film with good mechanical properties. The film samples were characterized by 13C-NMR, FTIR, DSC, X-Ray and SEM. The FTIR spectrum shows a sharp NH band and a very small urethane band. The 13C-NMR spectrum revealed a peak at 20 ppm, that can be attributed to the CH3 of the polyether chain, and two small peaks at 117 and 140 ppm, attributed to the aromatic ring. The X-ray diffractograms also indicated that after the grafting reaction, the samples of amylopectin-rich starch are more amorphous. Moreover, the glass transition temperature (Tg dropped from 50 °C to -11 °C. These results indicate formation of grafted products and the low Tg of the samples suggests that polyether-grafted starch is a good candidate to obtain solid polymeric electrolytes.

  16. Effects of trace element concentration on enzyme controlled stable isotope fractionation during aerobic biodegradation of toluene.

    Science.gov (United States)

    Mancini, Silvia A; Hirschorn, Sarah K; Elsner, Martin; Lacrampe-Couloume, Georges; Sleep, Brent E; Edwards, Elizabeth A; Lollar, Barbara Sherwood

    2006-12-15

    The effects of iron concentration on carbon and hydrogen isotopic fractionation during aerobic biodegradation of toluene by Pseudomonas putida mt-2 were investigated using a low iron medium and two different high iron media. Mean carbon enrichment factors (epsilonc) determined using a Rayleigh isotopic model were smaller in culture grown under high iron conditions (epsilonc = -1.7+/-0.1%) compared to low iron conditions (epsilonc = -2.5+/-0.3%). Mean hydrogen enrichment factors (epsilonH) were also significantly smaller for culture grown under high iron conditions (epsilonH = -77 +/-4%) versus low iron conditions (EpsilonH = -159+/-11%). A mechanistic model for enzyme kinetics was used to relate differences in the magnitude of isotopic fractionation for low iron versus high iron cultures to the efficiency of the enzymatic transformation. The increase of carbon and hydrogen enrichment factors at low iron concentrations suggests a slower enzyme-catalyzed substrate conversion step (k2) relative to the enzyme-substrate binding step (k-l) at low iron concentration. While the observed differences were subtle and, hence, do not significantly impact the ability to use stable isotope analysis in the field, these results demonstrated that resolvable differences in carbon and hydrogen isotopic fractionation were related to low and high iron conditions. This novel result highlights the need to further investigate the effects of other trace elements known to be key components of biodegradative enzymes.

  17. Safety enhancement by transposition of the nitration of toluene from semi-batch reactor to continuous intensified heat exchanger reactor

    OpenAIRE

    Di Miceli Raimondi, Nathalie; Olivier Maget, Nelly; Gabas, Nadine; Cabassud, Michel; Gourdon, Christophe

    2015-01-01

    International audience; The behaviour of a continuous intensified heat exchanger (HEX) reactor in case of process failure is analysed and compared to the behaviour of a semi-continuous reactor. The nitration of toluene is considered as test reaction to identify the main failure scenarios that can lead to thermal runaway in both processes using the HAZOP method.No flow rate of process fluid and utility fluid in the continuous process. No stirring during feeding of the reactor followed by norma...

  18. Evaluation of the UNC toluene-SOA mechanism with respect to other chamber studies and key model parameters

    Science.gov (United States)

    Hu, Di; Kamens, Richard M.

    In a companion paper by Hu et al. [2007. A kinetic mechanism for predicting secondary organic aerosol formation from toluene oxidation in the presence of NO x and natural sunlight. Atmospheric Environment, doi:10.1016/j.atmosenv.2007.04.025], a kinetic mechanism was developed from data generated in the University of North Carolina's (UNC) 270 m 3 dual outdoor aerosol smog chamber, to predict secondary organic aerosol (SOA) formation from toluene oxidation in the atmosphere. In this paper, experimental data sets from European Photoreactor (EUPHORE), smog chambers at the California Institute of Technology (Caltech), and the UNC 300 m 3 dual-outdoor gas phase chamber were used to evaluate the toluene mechanism. The model simulates SOA formation for the 'low-NO x' and 'mid-NO x' experiments from EUPHORE chambers reasonably well, but over-predicts SOA mass concentrations for the 'high-NO x' run. The model well simulates the SOA mass concentrations observed from the Caltech chambers. Experiments with the three key toluene products, 1,4-butenedial, 4-oxo-2-pentenal and o-cresol in the presence of oxides of nitrogen (NO x) are also simulated by the developed mechanism. The model well predicts the NO x time-concentration profiles and the decay of these two carbonyls, but underestimates ozone (O 3) formation for 4-oxo-2-pentenal. It well simulates SOA formation from 1,4-butenedial but overestimates (possibly due to experimental problems) the measured aerosol mass concentrations from 4-oxo-2-pentenal. The model underestimates SOA production from o-cresol, mostly due to its under-prediction of o-cresol decay. The effects of varying temperature, relative humidity, glyoxal uptake, organic nitrate yields, and background seed aerosol concentrations, were also investigated.

  19. Response and recovery of a pristine groundwater ecosystem impacted by toluene contamination - A meso-scale indoor aquifer experiment

    Science.gov (United States)

    Herzyk, Agnieszka; Fillinger, Lucas; Larentis, Michael; Qiu, Shiran; Maloszewski, Piotr; Hünniger, Marko; Schmidt, Susanne I.; Stumpp, Christine; Marozava, Sviatlana; Knappett, Peter S. K.; Elsner, Martin; Meckenstock, Rainer; Lueders, Tillmann; Griebler, Christian

    2017-12-01

    Microbial communities are the driving force behind the degradation of contaminants like aromatic hydrocarbons in groundwater ecosystems. However, little is known about the response of native microbial communities to contamination in pristine environments as well as their potential to recover from a contamination event. Here, we used an indoor aquifer mesocosm filled with sandy quaternary calciferous sediment that was continuously fed with pristine groundwater to study the response, resistance and resilience of microbial communities to toluene contamination over a period of almost two years, comprising 132 days of toluene exposure followed by nearly 600 days of recovery. We observed an unexpectedly high intrinsic potential for toluene degradation, starting within the first two weeks after the first exposure. The contamination led to a shift from oxic to anoxic, primarily nitrate-reducing conditions as well as marked cell growth inside the contaminant plume. Depth-resolved community fingerprinting revealed a low resistance of the native microbial community to the perturbation induced by the exposure to toluene. Distinct populations that were dominated by a small number of operational taxonomic units (OTUs) rapidly emerged inside the plume and at the plume fringes, partially replacing the original community. During the recovery period physico-chemical conditions were restored to the pristine state within about 35 days, whereas the recovery of the biological parameters was much slower and the community composition inside the former plume area had not recovered to the original state by the end of the experiment. These results demonstrate the low resilience of sediment-associated groundwater microbial communities to organic pollution and underline that recovery of groundwater ecosystems cannot be assessed solely by physico-chemical parameters.

  20. 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.)

  1. Photocatalytic oxidation of toluene in presence of water vapor using sol-gel synthesized N-doped TiO2

    Science.gov (United States)

    Van Sau, Nguyen; An, Ngo Thanh; Long, Nguyen Quang

    2017-09-01

    Toluene removal by photocatalytic oxidation in presence of water vapor was investigated on N-doped TiO2. The photocatalyst was prepared by a sol-gel method and characterized by various techniques. The conversion of toluene by photocatalytic oxidation in the presence of water vapor was reported at different reaction conditions, such as various reaction temperatures, various toluene/ water vapor concentrations. By using Langmuir- Hinshelwood model the activation energy (Ea) of the reaction of 1.33 kcal/mol was obtained. The heat of toluene adsorption and the heat of water vapor adsorption on the N-doped TiO2 catalyst were approximately -3.47 kcal/mol and -3.30 kcal/mol, respectively.

  2. Activity and three-dimensional distribution of toluene-degrading Pseudomonas putida in a multispecies biofilm assessed by quantitative in situ hybridization and scanning confocal laser microscopy

    DEFF Research Database (Denmark)

    Møller, Søren; Pedersen, Anne Rathmann; Poulsen, L.K.

    1996-01-01

    As a representative member of the toluene-degrading population in a biofilter for waste gas treatment, Pseudomonas putida was investigated with a 16S rRNA targeting probe, The three-dimensional distribution of P. putida was visualized in the biofilm matrix by scanning confocal laser microscopy....... demonstrating that P. putida was present throughout the biofilm. Acridine orange staining revealed a very heterogeneous structure of the fully hydrated biofilm, with cell-free channels extending ft om the surface Into the biofilm. This indicated that toluene may penetrate to deeper layers of the biofilm......, and consequently P. putida may be actively degrading toluene in all regions of the biofilm. Furthermore, measurements of growth rate-related parameters fur P. putida showed reduced I RNA content and cell size (relative to that ill a batch culture), indicating that the P. putida population mas not degrading toluene...

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

    International Nuclear Information System (INIS)

    Gonzalez, Emilio J.; Calvar, Noelia; Gonzalez, Begona; Dominguez, Angeles

    2010-01-01

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

  4. Determination of Xylene and Toluene by Solid-Phase Microextraction Using Au Nanoparticles-Thiol Silane Film Coupled to Ion Mobility Spectrometry.

    Science.gov (United States)

    Allafchian, Ali Reza; Akhgar, Ava; Ielbeigi, Vahideh; Tabrizchi, Mahmoud

    2016-11-01

    A simple, rapid and sensitive method for analysis of xylene and toluene was developed using the solid-phase microextraction (SPME) combined with ion mobilityspectrometry (IMS). Gold nanoparticles-thiol silane film (Au NPs-TSF) was applied as a newsorbent for SPME. Thiol silane film was formed on the surface of a stainless steel wire through incorporating Au nanoparticles during synthesis using sol-gel technique. The extraction properties of the fiber to xylene and toluene were examined, using a SPME device and thermal desorption ininjection port of IMS. The calibration graphs were linear in the range of 1.10-32.0 and 16.0-112.0 ppb for xylene and toluene, respectively. The detection limits for xylene and toluene were 0.7 and 8.0 ppb, respectively. The proposed method was applied without any considerable sample pretreatment and it was found to be simple enough to be strongly recommended for real sample analysis.

  5. Theoretical Prediction of Rate Constants for Hydrogen Abstraction by OH, H, O, CH3, and HO2 Radicals from Toluene.

    Science.gov (United States)

    Li, Shu-Hao; Guo, Jun-Jiang; Li, Rui; Wang, Fan; Li, Xiang-Yuan

    2016-05-26

    Hydrogen abstraction from toluene by OH, H, O, CH3, and HO2 radicals are important reactions in oxidation process of toluene. Geometries and corresponding harmonic frequencies of the reactants, transition states as well as products involved in these reactions are determined at the B3LYP/6-31G(2df,p) level. To achieve highly accurate thermochemical data for these stationary points on the potential energy surfaces, the Gaussian-4(G4) composite method was employed. Torsional motions are treated either as free rotors or hindered rotors in calculating partion functions to determine thermodynamic properties. The obtained standard enthalpies of formation for reactants and some prodcuts are shown to be in excellent agreement with experimental data with the largest error of 0.5 kcal mol(-1). The conventional transition state theory (TST) with tunneling effects was adopted to determine rate constants of these hydrogen abstraction reactions based on results from quantum chemistry calculations. To faciliate its application in kinetic modeling, the obtained rate constants are given in Arrhenius expression: k(T) = AT(n) exp(-EaR/T). The obtained reaction rate constants also agree reasonably well with available expermiental data and previous theoretical values. Branching ratios of these reactions have been determined. The present reaction rates for these reactions have been used in a toluene combustion mechanism, and their effects on some combustion properties are demonstrated.

  6. Isobaric (vapour + liquid) equilibria for sulfolane with toluene, ethylbenzene, and isopropylbenzene at 101.33 kPa

    International Nuclear Information System (INIS)

    Wang Zhengrong; Huang Lei; Xia Shuqian; Ma Peisheng

    2011-01-01

    Highlights: → The VLE data of toluene, ethylbenzene, isopropylbenzene with sulfolane were measured. → Both NRTL and UNIQUAC models can fit the experimental data well. → The new group interaction parameters of UNIFAC were regressed from the VLE data. → The estimated result shows that the group interaction parameters are reliable. - Abstract: Isobaric (vapour + liquid) equilibrium data have been measured for the (toluene + sulfolane), (ethylbenzene + sulfolane), and (isopropylbenzene + sulfolane) binary systems with a modified Rose-Williams still at 101.33 kPa. The experimental data of binary systems were well correlated by the non-random two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models for the liquid phase. All the experimental results passed the thermodynamic consistency test by the Herington method. Furthermore, the model UNIFAC (Do) group contribution method was used. Sulfolane is treated as a group (TMS), the new group interaction parameters for CH 2 -TMS, ACH-TMS and ACCH 2 -TMS were regressed from the VLE data of (toluene + sulfolane) and (ethylbenzene + sulfolane) binary systems. Then these group interaction parameters were used to estimate phase equilibrium data of the (isopropylbenzene + sulfolane) binary system. The results showed that the estimated data were in good agreement with the experimental values. The maximum and average absolute deviations of the temperature were 4.50 K and 2.39 K, respectively. The maximum and average absolute deviations for the vapour phase compositions of isopropylbenzene were 0.0237 and 0.0137, respectively.

  7. Isobaric (vapour + liquid) equilibria for sulfolane with toluene, ethylbenzene, and isopropylbenzene at 101.33 kPa

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhengrong; Huang Lei [Key Laboratory for Green Chemical Technology of State Education Ministry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Xia Shuqian, E-mail: shuqianxia@tju.edu.cn [Key Laboratory for Green Chemical Technology of State Education Ministry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Ma Peisheng [Key Laboratory for Green Chemical Technology of State Education Ministry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2011-12-15

    Highlights: > The VLE data of toluene, ethylbenzene, isopropylbenzene with sulfolane were measured. > Both NRTL and UNIQUAC models can fit the experimental data well. > The new group interaction parameters of UNIFAC were regressed from the VLE data. > The estimated result shows that the group interaction parameters are reliable. - Abstract: Isobaric (vapour + liquid) equilibrium data have been measured for the (toluene + sulfolane), (ethylbenzene + sulfolane), and (isopropylbenzene + sulfolane) binary systems with a modified Rose-Williams still at 101.33 kPa. The experimental data of binary systems were well correlated by the non-random two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models for the liquid phase. All the experimental results passed the thermodynamic consistency test by the Herington method. Furthermore, the model UNIFAC (Do) group contribution method was used. Sulfolane is treated as a group (TMS), the new group interaction parameters for CH{sub 2}-TMS, ACH-TMS and ACCH{sub 2}-TMS were regressed from the VLE data of (toluene + sulfolane) and (ethylbenzene + sulfolane) binary systems. Then these group interaction parameters were used to estimate phase equilibrium data of the (isopropylbenzene + sulfolane) binary system. The results showed that the estimated data were in good agreement with the experimental values. The maximum and average absolute deviations of the temperature were 4.50 K and 2.39 K, respectively. The maximum and average absolute deviations for the vapour phase compositions of isopropylbenzene were 0.0237 and 0.0137, respectively.

  8. 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.

  9. Adsorption of BTX (benzene, toluene, o-xylene, and p-xylene) from aqueous solutions by modified periodic mesoporous organosilica.

    Science.gov (United States)

    Moura, Cícero P; Vidal, Carla B; Barros, Allen L; Costa, Luelc S; Vasconcellos, Luiz C G; Dias, Francisco S; Nascimento, Ronaldo F

    2011-11-15

    The capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50 min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich-Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene>o-xylene>p-xylene>toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Influence of evaporation and solvent mixtures on the absorption of toluene and n-butanol in human skin in vitro.

    Science.gov (United States)

    Boman, A; Maibach, H I

    2000-03-01

    The influence of forced ventilation on the percutaneous absorption of butanol and toluene was studied in vitro. Human skin was exposed to the neat solvents and the solvents in binary mixtures with each other and in ternary mixtures with chloroform:methanol. The exposure was either unventilated or ventilated with various flow rates. At the ventilated exposure the skin absorption of all solvents and solvent mixtures was markedly reduced compared to unventilated exposure. Exposure with solvent mixtures increased the amounts of solvent absorbed as well as absorption rates. The absorption of the butanol component was most influenced. Increase in absorption was 11 to 9 times depending on whether toluene or chloroform/methanol was cosolvent. There was also an interindividual variation of absorption rate, varying with a factor of 3.5 for toluene and 4.3 for n-butanol within the 3 skin donors used. Skin absorption of volatile organic solvents at continuous ventilated conditions is related to their volatility and to the ventilation rate.A sufficient workplace ventilation is an important occupational hygienic measure not only to reduce exposure via respiration but to reduce absorption via the skin of volatile compounds as well.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-01-01

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

  12. Toluene Removal from Sandy Soils via In Situ Technologies with an Emphasis on Factors Influencing Soil Vapor Extraction

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Amin

    2014-01-01

    Full Text Available The integration of bioventing (BV and soil vapor extraction (SVE appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5% of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater.

  13. The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode

    OpenAIRE

    Hossein Ali Rangkooy; Fatemeh Tanha; Neamat Jaafarzadeh; Abolfazl Mohammadbeigi

    2017-01-01

    The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ...

  14. Evaporative Gasoline Emissions and Asthma Symptoms

    Science.gov (United States)

    Gordian, Mary Ellen; Stewart, Alistair W; Morris, Stephen S

    2010-01-01

    Attached garages are known to be associated with indoor air volatile organic compounds (VOCs). This study looked at indoor exposure to VOCs presumably from evaporative emissions of gasoline. Alaskan gasoline contains 5% benzene making benzene a marker for gasoline exposure. A survey of randomly chosen houses with attached garages was done in Anchorage Alaska to determine the exposure and assess respiratory health. Householders were asked to complete a health survey for each person and a household survey. They monitored indoor air in their primary living space for benzene, toluene, ethylbenzene and xylenes for one week using passive organic vapor monitoring badges. Benzene levels in homes ranged from undetectable to 58 parts per billion. The median benzene level in 509 homes tested was 2.96 ppb. Elevated benzene levels in the home were strongly associated with small engines and gasoline stored in the garage. High concentrations of benzene in gasoline increase indoor air levels of benzene in residences with attached garages exposing people to benzene at levels above ATSDR’s minimal risk level. Residents reported more severe symptoms of asthma in the homes with high gasoline exposure (16%) where benzene levels exceeded the 9 ppb. PMID:20948946

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-11-01

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

  16. Characterization of toluene and ethylbenzene biodegradation under nitrate-, iron(III)- and manganese(IV)-reducing conditions by compound-specific isotope analysis

    International Nuclear Information System (INIS)

    Dorer, Conrad; Vogt, Carsten; Neu, Thomas R.; Stryhanyuk, Hryhoriy; Richnow, Hans-Hermann

    2016-01-01

    Ethylbenzene and toluene degradation under nitrate-, Mn(IV)-, or Fe(III)-reducing conditions was investigated by compound specific stable isotope analysis (CSIA) using three model cultures (Aromatoleum aromaticum EbN1, Georgfuchsia toluolica G5G6, and a Azoarcus-dominated mixed culture). Systematically lower isotope enrichment factors for carbon and hydrogen were observed for particulate Mn(IV). The increasing diffusion distances of toluene or ethylbenzene to the solid Mn(IV) most likely caused limited bioavailability and hence resulted in the observed masking effect. The data suggests further ethylbenzene hydroxylation by ethylbenzene dehydrogenase (EBDH) and toluene activation by benzylsuccinate synthase (BSS) as initial activation steps. Notably, significantly different values in dual isotope analysis were detected for toluene degradation by G. toluolica under the three studied redox conditions, suggesting variations in the enzymatic transition state depending on the available TEA. The results indicate that two-dimensional CSIA has significant potential to assess anaerobic biodegradation of ethylbenzene and toluene at contaminated sites. - Highlights: • Toluene/ethylbenzene isotope effects were studied in 3 cultures with varying TEAs. • BTEX biodegradation under solid Mn(IV) was investigated by CSIA for the first time. • Solid Mn(IV) as TEA always caused significant lower C and H isotope enrichment. • Always similar correlation of C–H-isotopes upon ethylbenzene activation was shown. • Subtypes of benzylsuccinate synthase may cause varying correlation of C–H-isotopes.

  17. Influence of toluene and salinity on biosurfactant production by Bacillus sp.: scale up from flasks to a bench-scale bioreactor

    Directory of Open Access Journals (Sweden)

    Ellen Cristina Souza

    Full Text Available ABSTRACT To select the best biosurfactant producer, Pseudomonas putida, Bacillus megatherium, Bacillus licheniformis and Bacillus subtilis were cultured in flasks on media with different salinity [low salinity (LS, Bushnell-Haas (BH and artificial sea water (SW media] supplemented or not with toluene as a model pollutant. Toluene inhibited the growth of all microorganisms and stimulated the biosurfactant production. B. subtilis exhibited the best performance, being able to lower the surface tension (ST in the LS medium to 65.5 mN/min in the absence of toluene, and to 46.5 mN/min in the BH medium in the presence of toluene, corresponding to ST reductions of 13.0 and 27.5 mN/m, respectively. Scaling up the process to a bench-scale fermentor, the best results were obtained in the LS medium, where B. subtilis was able to reduce the toluene concentration from 26.0 to 4.3 g/L within 12 h and ST by 17.2 mN/m within 18 h. The results of this study point out that B. subtilis is an interesting biosurfactant producer, which could be used in the bioremediation of toluene-contaminated water.

  18. Initial Symptoms of ALS

    Science.gov (United States)

    ... Chapters Certified Centers and Clinics Support Groups About ALS About Us Our Research In Your Community Advocate ... Diagnosis En español Symptoms The initial symptoms of ALS can be quite varied in different people. One ...

  19. Brain Tumor Symptoms

    Science.gov (United States)

    ... Brain Anatomy Brain Tumor Symptoms Headaches Seizures Memory Depression Mood Swings & Cognitive Changes Fatigue Other Symptoms Diagnosis Types of Tumors Risk Factors Brain Tumor Statistics Brain Tumor Dictionary Webinars Anytime Learning About Us ...

  20. Symptoms of Blood Disorders

    Science.gov (United States)

    ... In This Article Generic Name Select Brand Names aspirin No US brand name Symptoms and Diagnosis of Blood Disorders Overview of Blood Disorders Symptoms of Blood Disorders Medical History and Physical Examination for Blood Disorders Laboratory Tests ...

  1. Functional sensory symptoms

    NARCIS (Netherlands)

    Stone, J.; Vermeulen, M.

    2017-01-01

    Functional (psychogenic) sensory symptoms are those in which the patient genuinely experiences alteration or absence of normal sensation in the absence of neurologic disease. The hallmark of functional sensory symptoms is the presence of internal inconsistency revealing a pattern of symptoms

  2. The correlation of Mycolic acid production by a toluene degrading Mycobacterium in the presence of cholesterol

    Directory of Open Access Journals (Sweden)

    Giti Emtiazi *

    2013-01-01

    Full Text Available Introduction: Cell wall mycolic acids (MA from Mycobacterium tuberculosis are presented as antigens that can be used to detect antibodies as surrogate markers of active Tuberculosis (TB disease, even in HIV coinfected patients. The use of the complex mixtures of natural MA is complicated by apparent antibody cross-reactivity with cholesterol. Mycolic acid is not only related to diagnosis of TB disease but also similar structure of mycolic acid in saprophyte strains are excellent candidate for drug delivery especially for nasal spray. The aim of this work was to investigate the effect of cholesterol on mycolic acid synthesis and potential of saprophyte mycolic acid to drug delivery. Materials and methods: Toluene enrichment medium was used for isolation of mycolic acid producing bacteria. A fast growing, acid fast bacterium was identified by PCR reaction and the related sequence of 16S rRNA gene was deposited in the NCBI Genbank with accession number jn64433. Production of mycolic acid was investigated by high-performance liquid chromatography (HPLC in different media. Results: Here the effect of cholesterol on biosynthesis of mycolic acids by saprophyte Mycobacterium isolated from marine water is was reported. HPLC analyses showed the mycolic acid extracted from saprophyte. Mycobacterium had one, early, cluster of peaks, like Mycobacterium tuberculosis and Mobacterium bovis.This strain is a fast growing bacterium and cholesterol might promote longer fatty acid production. Discussion and conclusion: The similarity between mycolic acid from isolated and patogenic mycobacteria offers that mycolic acid obtained from saprophyte Mycobacterium can be useful as a drug carrier. Addition of egg yolk to media induced longer fatty acid production by isolating that is suitable for delivery of drugs into the macrophage.

  3. Investigation of a cylindrical chemosorptive denuder for sampling and phase separation of toluene diisocyanate aerosols.

    Science.gov (United States)

    Nordqvist, Yvonne; Nilsson, Ulrika; Colmsjö, Anders

    2005-07-01

    A cylindrical chemosorptive denuder in series with a glass fibre filter has been evaluated for sampling toluene diisocyanate (TDI) aerosols. The sampler is designed for measuring personal exposure to diisocyanates. Several denuder coatings and derivatising reagents were investigated. Dimethylpolysiloxane (SE-30) and 5% phenyl dimethylpolysiloxane (SE-54) with either dibutylamine (DBA) or dipentylamine (DPeA) as derivatising reagents yielded the lowest vapour breakthrough (the amount (%) of the vapour that passes through the denuder), close to values predicted by theory. Immobilisation of the SE-30 denuder coating by in-situ cross-linking yielded comparable results. With an SE-30/DBA-coated denuder operating within an airflow range of 100-500 mL min(-1), the phase separation was shown to be consistent with theoretical predictions derived by use of the Gormley-Kennedy equation. This provides a means of calculating the vapour breakthrough and correcting experimentally obtained values with regard to vapour-particulate phase distribution, suggesting that the denuder can provide accurate phase-distribution measurements. The SE-30/DBA denuder can be used over a concentration range spanning nearly six orders of magnitude. Its capacity is sufficient to perform 15-min exposure measurements of a TDI aerosol with air concentrations as high as 1,700 microg m(-3), 40 times higher than the Swedish occupational exposure limit (OEL). At the other end of the range, the estimated limit of detection (LOD) was less than 2 ng m(-3) for both the vapour and the aerosol phases when LC-ESI-MS-MS was used for chemical analysis.

  4. Titanium dioxide coated cementitious materials for air purifying purposes: Preparation, characterization and toluene removal potential

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Anibal Maury; De Belie, Nele [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Engineering Faculty, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Demeestere, Kristof [Research Group EnVOC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653. B-9000 Ghent (Belgium); Maentylae, Tapio; Levaenen, Erkki [Department of Materials Science, Tampere University of Technology, Korkeakoulunkatu 6, FIN-33720 Tampere (Finland)

    2010-04-15

    This work presents promising results for air purification by heterogeneous photocatalysis on new titanium dioxide loaded cementitious materials. A set of eight concretes and plasters is enriched with TiO{sub 2} photocatalyst by dip-coating and/or sol-gel methods. First, the macro-structural features of the cementitious materials have been studied in terms of porosity and roughness. The first parameter has been determined using mercury intrusion porosimetry or by vacuum saturation, and ranged between 9 and 75%, with the highest values obtained for autoclaved aerated white concrete. Surface roughness, determined by laser profilometry, has been characterized by the R{sub a} factor. This expresses the mean deviation of the profile from the centre line and ranged between 0.7 and 252 {mu}m, with the highest value obtained for conventional grey concrete finished with surface brush. Secondly, the weathering resistance of the TiO{sub 2} coatings has been determined by exposing them to different abrasive conditions and by performing SEM-Edax analyses to measure quantitatively the coating's titanium content. Hereby, it is shown that high porosity and roughness are favourable for TiO{sub 2} particles retention. Finally, the preliminary air purification potential of both dip-coated and sol-gel coated TiO{sub 2} enriched concrete samples has been investigated on lab-scale using toluene as a model pollutant. High removal efficiencies (up to 86%) were obtained with the dip-coated samples, indicating their attractive photocatalytic properties for future application as air purifying building materials. (author)

  5. Degradation of toluene, ethylbenzene, and xylene using heat and chelated-ferrous iron activated persulfate oxidation

    Science.gov (United States)

    Mondal, P.; Sleep, B.

    2014-12-01

    Toluene, ethylbenze, and xylene (TEX) are common contaminants in the subsurface. Activated persulfate has shown promise for degrading a wide variety of organic compounds. However, studies of persulfate application for in situ degradation of TEX and effects on the subsequent bioremediation are limited. In this work, degradation studies of TEX in aqueous media and soil are being conducted using heat activated and chelated-ferrous iron activated persulfate oxidation in batch and flow-through column experiments. In the batch experiments, sodium persulfate is being used at different concentrations to provide an initial persulfate to TEX molar ratios between 10:1 and 100:1. Sodium persulfate solutions are being activated at 20, 37, 60, and 80 oC temperatures for the heat activated oxidation. For the chelated-ferrous iron activated oxidation, ferrous iron and citric acid, both are being used at concentration of 5 mM. In the experiments with soil slurry, a soil to water ratio of 1 to 5 is being used. Flow through water saturated column experiments are being conducted with glass columns (45 cm in length and 4 cm in diameter) uniformly packed with soils, and equilibrated with water containing TEX at the target concentrations. Both the heat activation and chelated-ferrous iron activation of persulfate are being employed in the column experiments. Future experiments are planned to determine the suitability of persulfate oxidation of TEX on the subsequent biodegradation using batch microcosms containing TEX degrading microbial cultures. In these experiments, the microbial biomass will be monitored using total phospholipids, and the microbial community will be determined using quantitative real-time polymerase chain reaction (qPCR) on the extracted DNA. This study is expected to provide suitable operating conditions for in situ chemical oxidation of TEX with activated persulfate followed by bioremediation.

  6. Hydrogen abstraction mechanisms and reaction rates of toluene+NO3.

    Science.gov (United States)

    Ma, Yongmei; Su, Kehe; Zhang, Jin; Wang, Yanli; Wang, Xin; Liu, Yan

    2015-08-01

    The hydrogen abstraction reaction mechanisms of toluene molecule by NO3 radical were investigated theoretically with quantum chemistry and reaction kinetics. All the molecular structures, vibrational properties, and the intrinsic reaction coordinates were determined with B3LYP/6-311G(d,p). The non-dynamic electronic correlations were examined with the CASSCF dominant configurations. The energies and the potential energy profiles were refined with accurate model chemistry G3(MP2). Rate constants were determined using the CVT method over the temperature range 200-2000 K. It was found that in addition to the side chain H-abstraction, the ring H-abstraction reactions are also possible. The side chain H-abstraction rate constant is in very good agreement with the available experiments and has a non-Arrhenius characteristic. Nevertheless, all the ring H-abstractions follow the Arrhenius behavior well. The over-all reaction was found to have a complex reaction mechanism in which the side chain H-abstraction is dominant below 700 K while the ring H-abstractions are competitive above 800 K. The approximate apparent activation energies E app are 15.5 and 66.4 kJ mol(-1) at 300-700 K and 800-2000 K, respectively. Graphical Abstract The calculation of the reaction rate indicates that the over-all reaction has a complex mechanism. The reaction proceeds mainly by the side chain H-abstraction at temperatures lower than 700 K and is nearly irreversible, while the competition of the ring H-abstractions becomes observable at higher temperatures and is reversible.

  7. Self-Organized TiO₂-MnO₂ Nanotube Arrays for Efficient Photocatalytic Degradation of Toluene.

    Science.gov (United States)

    Nevárez-Martínez, María C; Kobylański, Marek P; Mazierski, Paweł; Wółkiewicz, Jolanta; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

    2017-03-31

    Vertically oriented, self-organized TiO₂-MnO₂ nanotube arrays were successfully obtained by one-step anodic oxidation of Ti-Mn alloys in an ethylene glycol-based electrolyte. The as-prepared samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis absorption, photoluminescence spectroscopy, X-ray diffraction (XRD), and micro-Raman spectroscopy. The effect of the applied potential (30-50 V), manganese content in the alloy (5-15 wt. %) and water content in the electrolyte (2-10 vol. %) on the morphology and photocatalytic properties was investigated for the first time. The photoactivity was assessed in the toluene removal reaction under visible light, using low-powered LEDs as an irradiation source (λ max = 465 nm). Morphology analysis showed that samples consisted of auto-aligned nanotubes over the surface of the alloy, their dimensions were: diameter = 76-118 nm, length = 1.0-3.4 μm and wall thickness = 8-11 nm. It was found that the increase in the applied potential led to increase the dimensions while the increase in the content of manganese in the alloy brought to shorter nanotubes. Notably, all samples were photoactive under the influence of visible light and the highest degradation achieved after 60 min of irradiation was 43%. The excitation mechanism of TiO₂-MnO₂ NTs under visible light was presented, pointing out the importance of MnO₂ species for the generation of e - and h⁺.

  8. Removal of gaseous toluene by the combination of photocatalytic oxidation under complex light irradiation of UV and visible light and biological process.

    Science.gov (United States)

    Wei, Zaishan; Sun, Jianliang; Xie, Zhirong; Liang, Mingyan; Chen, Shangzhi

    2010-05-15

    Photocatalysis is a promising technology for treatment of gaseous waste; its disadvantages, however, include causing secondary pollution. Biofiltration has been known as an efficient technology for treatment volatile organic compounds (VOCs) at low cost of maintenance, and produces harmless by-products; its disadvantages, include large volume of bioreactor and slow adaptation to fluctuating concentrations in waste gas. A bench scale system integrated with a photocatalytic oxidation and a biofilter unit for the treatment of gases containing toluene was investigated. The integrated system can effectively oxidize toluene with high removal efficiency. The photocatalytic activity of N-TiO(2)/zeolite was evaluated by the decomposition of toluene in air under UV and visible light (VL) illumination. The N-TiO(2)/zeolite has more photocatalytic activity under complex light irradiation of UV and visible light for toluene removal than that of pure TiO(2)/zeolite under UV or visible light irradiation. N-TiO(2)/zeolite was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrum analysis (XPS), Fourier transform infrared spectroscopy (FT-IR), and as-obtained products were identified by means of gas chromatography/mass spectrometry (GC/MS). Results revealed that the photocatalyst was porous and was high photoactive for mineralizing toluene. The high activity can be attributed to the results of the synergetic effects of strong UV and visible light absorption, surface hydroxyl groups. The photocatalytic degradation reaction of toluene with the N-TiO(2)/zeolite follows Langmuir-Hinshelwood kinetics. Toluene biodegradation rate matches enzymatic oxidation kinetics model. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  9. The aromatic volatile organic compounds toluene, benzene and styrene induce COX-2 and prostaglandins in human lung epithelial cells via oxidative stress and p38 MAPK activation.

    Science.gov (United States)

    Mögel, Iljana; Baumann, Sven; Böhme, Alexander; Kohajda, Tibor; von Bergen, Martin; Simon, Jan-Christoph; Lehmann, Irina

    2011-10-28

    Toluene, benzene and styrene are volatile organic compounds (VOCs) widely distributed in the environment. Tobacco smoke, traffic exposure and solvents used for paints, rubber and adhesives are known sources for these compounds. The aim of the present study was to investigate whether toluene, benzene and styrene can induce inflammatory reactions in lung cells and to characterize possible underlying mechanisms. A previous study gave evidence that expression of cyclooxygenase-2 (COX-2) is upregulated following exposure to the aromatic VOC chlorobenzene. Here, we investigated the effects of the aromatics toluene, benzene and styrene on human lung cells, with emphasis on COX-2, the rate-limiting enzyme of the prostaglandin pathway. In addition, we studied the potential role of oxidative stress and p38 MAPK activation in the toluene/benzene/styrene-dependent COX-2 induction. Following exposure to the aromatic compounds the expression level of COX-2 increased markedly. In addition, prostaglandin E(2) (PGE(2)) and prostaglandin F(2α) (PGF(2α)), major products of the COX enzyme, were found to be upregulated in response to toluene, benzene or styrene exposure. Furthermore, we observed an activation of p38 MAPK resulting from aromatic VOC exposure. Treatment of the cells with a specific p38 inhibitor (SB203580) or the antioxidant N-acetylcysteine (NAC) was able to prevent the toluene/benzene/styrene-dependent COX-2 activation, and subsequent increased PGE(2) and PGF(2α) secretion. These results suggest that toluene, benzene and styrene induce production and secretion of PGE(2) and PGF(2α) in lung epithelial cells via p38 MAPK and COX-2 activation in a redox sensitive manner. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  10. Quantitative detection of benzene in toluene- and xylene-rich atmospheres using high-kinetic-energy ion mobility spectrometry (IMS).

    Science.gov (United States)

    Langejuergen, Jens; Allers, Maria; Oermann, Jens; Kirk, Ansgar; Zimmermann, Stefan

    2014-12-02

    One major drawback of ion mobility spectrometry (IMS) is the dependence of the response to a certain analyte on the concentration of water or the presence of other compounds in the sample gas. Especially for low proton affine analytes, e.g., benzene, which often exists in mixtures with other volatile organic compounds, such as toluene and xylene (BTX), a time-consuming preseparation is necessary. In this work, we investigate BTX mixtures using a compact IMS operated at decreased pressure (20 mbar) and high kinetic ion energies (HiKE-IMS). The reduced electric field in both the reaction tube and the drift tube can be independently increased up to 120 Td. Under these conditions, the water cluster distribution of reactant ions is shifted toward smaller clusters independent of the water content in the sample gas. Thus, benzene can be ionized via proton transfer from H3O(+) reactant ions. Also, a formation of benzene ions via charge transfer from NO(+) is possible. Furthermore, the time for interaction between ions and neutrals of different analytes is limited to such an extent that a simultaneous quantification of benzene, toluene, and xylene is possible from low ppbv up to several ppmv concentrations. The mobility resolution of the presented HiKE-IMS varies from R = 65 at high field (90 Td) to R = 73 at lower field (40 Td) in the drift tube, which is sufficient to separate the analyzed compounds. The detection limit for benzene is 29 ppbv (2 s of averaging) with 3700 ppmv water, 12.4 ppmv toluene, and 9 ppmv xylene present in the sample gas. Furthermore, a less-moisture-dependent benzene measurement with a detection limit of 32 ppbv with ca. 21 000 ppmv (90% relative humidity (RH) at 20 °C) water present in the sample gas is possible evaluating the signal from benzene ions formed via charge transfer.

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

    International Nuclear Information System (INIS)

    Rubiano D, Maria del Pilar; Marciales C, Clara; Duarte A, Martha

    2002-01-01

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

  12. Antihistamines suppress upregulation of histidine decarboxylase gene expression with potencies different from their binding affinities for histamine H1 receptor in toluene 2,4-diisocyanate-sensitized rats

    Directory of Open Access Journals (Sweden)

    Hiroyuki Mizuguchi

    2016-04-01

    Full Text Available Antihistamines inhibit histamine signaling by blocking histamine H1 receptor (H1R or suppressing H1R signaling as inverse agonists. The H1R gene is upregulated in patients with pollinosis, and its expression level is correlated with the severity of nasal symptoms. Here, we show that antihistamine suppressed upregulation of histidine decarboxylase (HDC mRNA expression in patients with pollinosis, and its expression level was correlated with that of H1R mRNA. Certain antihistamines, including mepyramine and diphenhydramine, suppress toluene-2,4-diisocyanate (TDI-induced upregulation of HDC gene expression and increase HDC activity in TDI-sensitized rats. However, d-chlorpheniramine did not demonstrate any effect. The potencies of antihistamine suppressive effects on HDC mRNA elevation were different from their H1R receptor binding affinities. In TDI-sensitized rats, the potencies of antihistamine inhibitory effects on sneezing in the early phase were related to H1R binding. In contrast, the potencies of their inhibitory effects on sneezing in the late phase were correlated with those of suppressive effects on HDC mRNA elevation. Data suggest that in addition to the antihistaminic and inverse agonistic activities, certain antihistamines possess additional properties unrelated to receptor binding and alleviate nasal symptoms in the late phase by inhibiting synthesis and release of histamine by suppressing HDC gene transcription.

  13. Antihistamines suppress upregulation of histidine decarboxylase gene expression with potencies different from their binding affinities for histamine H1 receptor in toluene 2,4-diisocyanate-sensitized rats.

    Science.gov (United States)

    Mizuguchi, Hiroyuki; Das, Asish K; Maeyama, Kazutaka; Dev, Shrabanti; Shahriar, Masum; Kitamura, Yoshiaki; Takeda, Noriaki; Fukui, Hiroyuki

    2016-04-01

    Antihistamines inhibit histamine signaling by blocking histamine H1 receptor (H1R) or suppressing H1R signaling as inverse agonists. The H1R gene is upregulated in patients with pollinosis, and its expression level is correlated with the severity of nasal symptoms. Here, we show that antihistamine suppressed upregulation of histidine decarboxylase (HDC) mRNA expression in patients with pollinosis, and its expression level was correlated with that of H1R mRNA. Certain antihistamines, including mepyramine and diphenhydramine, suppress toluene-2,4-diisocyanate (TDI)-induced upregulation of HDC gene expression and increase HDC activity in TDI-sensitized rats. However, d-chlorpheniramine did not demonstrate any effect. The potencies of antihistamine suppressive effects on HDC mRNA elevation were different from their H1R receptor binding affinities. In TDI-sensitized rats, the potencies of antihistamine inhibitory effects on sneezing in the early phase were related to H1R binding. In contrast, the potencies of their inhibitory effects on sneezing in the late phase were correlated with those of suppressive effects on HDC mRNA elevation. Data suggest that in addition to the antihistaminic and inverse agonistic activities, certain antihistamines possess additional properties unrelated to receptor binding and alleviate nasal symptoms in the late phase by inhibiting synthesis and release of histamine by suppressing HDC gene transcription. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  14. Management of Menopausal Symptoms

    OpenAIRE

    Kaunitz, Andrew M.; Manson, JoAnn E.

    2015-01-01

    Most menopausal women experience vasomotor symptoms, with bothersome symptoms often lasting longer than one decade. Hormone therapy (HT) represents the most effective treatment for these symptoms, with oral and transdermal estrogen formulations having comparable efficacy. Findings from the Women’s Health Initiative and other recent randomized clinical trials have helped to clarify the benefits and risks of combination estrogen-progestin and estrogen-alone therapy. Absolute risks observed with...

  15. Early psychosis symptoms

    International Nuclear Information System (INIS)

    Naqvi, H.A.; Hussain, S.; Islam, M.

    2014-01-01

    Objective: To determine the prodromal symptoms of schizophrenia in the pathways to help-seeking. Study Design: A cross-sectional study. Place and Duration of Study: The Department of Psychiatry, the Aga Khan University, Karachi, from 2008 to 2009. Methodology: A total of 93 patients were interviewed in the pathways to care of schizophrenia. The diagnosis was based on ICD-10 criteria. The pathways to care were assessed through a semi-structured questionnaire. The onset, course and symptoms of psychosis were assessed through Interview for Retrospective Assessment at Age at Onset of Psychosis (IROAS). Results: Fifty five (59%) participants were male while 41% (n=38%) were female. Using IROAS, 108 symptoms were identified as concerning behaviour. Alternatively, 60 (55%) concerning behaviours were reported in the open-ended inquiry of the reasons for help seeking as assessed by the pathways to care questionnaire with a statistically significant difference between most symptoms category. The difference was most pronounced (p < 0.001) for depressed mood (66%), worries (65%), tension (63%), withdrawal/mistrust (54%) and loss of self-confidence (53%). Thought withdrawal (22%) and passivity (15%) were elicited only through structured interview (IROAS). When symptoms were categorized together, about 83% of the subjects presented with affective and non-specific prodromal symptoms. Roughly, 10% of the subjects presented with positive symptoms and 3% presented with the negative symptoms of psychosis. The non-specific, affective symptoms appear to predominate the prodromal phase of the illness. Conclusion: Prodromal symptoms of schizophrenia include non-specific, affective symptoms. Attention needs to be paid on identifying the prodromal symptoms and change in social functioning in order to identify those who are at risk of long term psychosis. (author)

  16. Somatic symptom disorder

    Science.gov (United States)

    ... disorder References American Psychiatric Association. Somatic symptom disorder. Diagnostic and Statistical Manual of Mental Disorders . 5th ed. Arlington, VA: American Psychiatric Publishing; 2013: ...

  17. Kwashiorkor symptoms (image)

    Science.gov (United States)

    ... Early symptoms include fatigue, irritability, and lethargy. As protein deprivation continues, one sees growth failure, loss of muscle mass, generalized swelling (edema), and decreased immunity. A large, ...

  18. Dynamic viscosity modeling of methane plus n-decane and methane plus toluene mixtures: Comparative study of some representative models

    DEFF Research Database (Denmark)

    Baylaucq, A.; Boned, C.; Canet, X.

    2005-01-01

    Viscosity measurements of well-defined mixtures are useful in order to evaluate existing viscosity models. Recently, an extensive experimental study of the viscosity at pressures up to 140 MPa has been carried out for the binary systems methane + n-decane and methane toluene, between 293.15 and 373.......15 and for several methane compositions. Although very far from real petroleum fluids, these mixtures are interesting in order to study the potential of extending various models to the simulation of complex fluids with asymmetrical components (light/heavy hydrocarbon). These data (575 data points) have been...

  19. Safety assessment of xylene sulfonic acid, toluene sulfonic acid, and alkyl aryl sulfonate hydrotropes as used in cosmetics.

    Science.gov (United States)

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

    2011-12-01

    Xylene sulfonic acid, toluene sulfonic acid, and alkyl aryl sulfonate hydrotropes used in cosmetics as surfactants, hydrotropes, were reviewed in this safety assessment. The similar structure, properties, functions, and uses of these ingredients enabled grouping them and using the available toxicological data to assess the safety of the entire group. The Cosmetic Ingredient Review Expert Panel reviewed relevant animal and human data related to these ingredients. The panel concluded that xylene sulfonic acid and alkyl aryl sulfonate hydrotropes are safe as cosmetic ingredients in the present practices of use and concentrations as described in this safety assessment, when formulated to be nonirritating.

  20. Kinetic isotope effect and tunnelling in the reaction between 4-nitrophenylnitromethane and pentamethylguanidine in acetonitrile and toluene

    International Nuclear Information System (INIS)

    Blanch, J.H.; Rogne, O.; Rossemyr, L.I.

    1980-01-01

    Rates and activation parameters for the proton and deuteron transfer reaction of 4-nitrophenylnitromethane with pentamethylguanidine in acetonitrile have been determined. The isotope effect and differences in activation parameters are larger than the semiclassical limits and suggest a small but significant tunnel correction. The results are well accounted for by Bell's equation for tunnelling through a parabolic barrier. Comparison of the results for acetonitrile with previously obtained values for toluene show that there is no significant effect of the solvent polarity on the tunnel correction. (author)

  1. Viscosity and density of tri-n-butyl phosphate + benzene + toluene from 30 C to 45 C

    International Nuclear Information System (INIS)

    Swain, N.; Chakravortty, V.

    1999-01-01

    Viscosities and densities of the ternary liquid mixtures of tri-n-butyl phosphate + benzene + toluene were measured at (30, 35, 40, and 45) C. The deviations in the viscosity from a mole fraction average were fitted in a Redlich-Kister type equation, which includes the contribution of each constituent binary system along with a ternary contribution term. The viscosity deviations were negative in most of the cases. Tri-n-butyl phosphate (TBP) is chosen as one of the components in ternary liquid mixtures as it is effective as an extractant for lanthanides and actinides. This extractant dominates the chemical reprocessing of nuclear fuels in the atomic energy industry

  2. Extraction of nitrates of lanthanoids (3) of the yttrium group and yttrium (3) by trialkylbenzylammonium nitrate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kovalev, S.V.; Keskinov, V.A.; Kopyrin, A.A.

    1997-01-01

    A study was made on extraction of nitrates of lanthanoids (3) of the yttrium group (terbium-lutetium) and yttrium (3) by trialkylbensylammonium nitrate in toluene at T=298.15 K pH 2. Extraction isotherms are described with account of formation of compound of (R 4 N) 2 [Ln(NO 3 ) 5 ] composition in organic phase. Values of extraction constants decreasing in terbium (3)-lutetium (3) series, were calculated. Value of extraction constant for yttrium (3) is close to the value of extraction constant for ytterbium (3). 13 refs., 2 figs., 3 tabs

  3. Phenyl-N,N-dibutylcarbamoylmethyl sulfoxide as a new bifunctional extractant for extraction of uranium(VI) in toluene

    International Nuclear Information System (INIS)

    Han Jing-Tian; Sun Guo-Xin; Shao Hua; Bao Bo-Rong; Chen Shu-Feng

    1999-01-01

    A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium(VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO 3 ). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species. (author)

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

    OpenAIRE

    Muliane Ulfi; Lestari Puji

    2018-01-01

    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 V...

  5. An analysis of factors that influence personal exposure to toluene and xylene in residents of Athens, Greece

    Directory of Open Access Journals (Sweden)

    Linos Athena

    2006-02-01

    Full Text Available Abstract Background Personal exposure to pollutants is influenced by various outdoor and indoor sources. The aim of this study was to evaluate the exposure of Athens citizens to toluene and xylene, excluding exposure from active smoking. Methods Passive air samplers were used to monitor volunteers, their homes and various urban sites for one year, resulting in 2400 measurements of toluene and xylene levels. Since both indoor and outdoor pollution contribute significantly to human exposure, volunteers were chosen from occupational groups who spend a lot of time in the streets (traffic policemen, bus drivers and postmen, and from groups who spend more time indoors (teachers and students. Data on individual and house characteristics were obtained using a questionnaire completed at the beginning of the study; a time-location-activity diary was also completed daily by the volunteers in each of the six monitoring campaigns. Results Average personal toluene exposure varied over the six monitoring campaigns from 53 to 80 μg/m3. Urban and indoor concentrations ranged from 47 – 84 μg/m3 and 30 – 51 μg/m3, respectively. Average personal xylene exposure varied between 56 and 85 μg/m3 while urban and indoor concentrations ranged from 53 – 88 μg/m3 and 27 – 48 μg/m3, respectively. Urban pollution, indoor residential concentrations and personal exposures exhibited the same pattern of variation during the measurement periods. This variation among monitoring campaigns might largely be explained by differences in climate parameters, namely wind speed, humidity and amount of sunlight. Conclusion In Athens, Greece, the time spent outdoors in the city center during work or leisure makes a major contribution to exposure to toluene and xylene among non-smoking citizens. Indoor pollution and means of transportation contribute significantly to individual exposure levels. Other indoor residential characteristics such as recent painting and mode of heating

  6. Isothermal Titration Calorimetry and Fluorescence Spectroscopy Study Of Asphaltene Self-Association In Toluene And Interaction With A Model Resin

    DEFF Research Database (Denmark)

    Garcia, Daniel Merino; Andersen, Simon Ivar

    2002-01-01

    This article collects the work performed by Isothermal Titration Caloritnetry (ITC) in the study of the self-association of asphaltenes in toluene solutions. Calorimetric experiments show that asphaltenes, start self-associating at very low concentrations and that the existence of a Critical...... with the results of the titration of three model molecules: nonylphenol, which associates by means of hydrogen bond formation, and coronene and pyrene, which associates by stacking. The results obtained leave open the question about the model-stacking molecules, as it was not possible to elucidate whether they do...

  7. Infrared Spectrum of Toluene: Comparison of Anharmonic Isolated-Molecule Calculations and Experiments in Liquid Phase and in a Ne Matrix.

    Science.gov (United States)

    Knaanie, Roie; Šebek, Jiří; Tsuge, Masashi; Myllys, Nanna; Khriachtchev, Leonid; Räsänen, Markku; Albee, Brian; Potma, Eric O; Gerber, R Benny

    2016-05-19

    First-principles anharmonic calculations are carried out for the CH stretching vibrations of isolated toluene and compared with the experimental infrared spectra of isotopologues of toluene in a Ne matrix at 3 K and of liquid toluene at room temperature. The calculations use the vibrational self-consistent field method and the B3LYP potential surface. In general, good agreement is found between the calculations and experiments. However, the spectrum of toluene in a Ne matrix is more complicated than that predicted theoretically. This distinction is discussed in terms of matrix-site and resonance effects. Interestingly, the strongest peak in the CH stretching spectrum has similar widths in the liquid phase and in a Ne matrix, despite the very different temperatures. Implications of this observation to the broadening mechanism are discussed. Finally, our results show that the B3LYP potential offers a good description of the anharmonic CH stretching band in toluene, but a proper description of matrix-site and resonance effects remains a challenge.

  8. Developed a needle trap device with PDMS sorbent for microextraction of toluene and methyl ethyl ketone from aquatic samples using dynamic headspace

    Directory of Open Access Journals (Sweden)

    Sara Karimi Zeverdegani

    2016-09-01

    Full Text Available Introduction: Due to the widespread use of toxic chemicals in most workplaces that can lead to toxic effects on human, various chemical extraction technique have been defined for analysis these toxic substances in air, water and biological samples. The purpose of this research is extraction of  toluene and methyl ethyl ketone from aquatic samples with needle trap device and  one commercial sorbent. Methods: In this research, needle trap device was used to extraction of  toluene and methyl ethyl ketone in aquatic samples, so needles(size 20 were packed with PDMS and extraction was done with dynamic headspace needle trap device. Gas chromatography with - flame ionization detector was used to analysis and optimized extraction of two substances were obtained. Results: Results show that the optimum temperature and time extraction was similar for toluene and methyl ethyl ketone (30 ° C, 30 min, but the reproducibility of results and calibration curve that obtained for toluene was better than methyl ethyl ketone. Conclusion: Needle trap technique is inexpensive, sensitive and portable also this method has good recovery to extract small amounts of  toluene and methyl ethyketon from aquatic samples with polydimethylsiloxane.

  9. Cocaine and Psychiatric Symptoms

    OpenAIRE

    Morton, W. Alexander

    1999-01-01

    Background: Cocaine is an addictive drug that produces numerous psychiatric symptoms, syndromes, and disorders. The symptoms include agitation, paranoia, hallucinations, delusions, violence, as well as suicidal and homicidal thinking. They can be primary to the drug's effect or secondary to exacerbation of comorbid psychiatric disorders.

  10. Bell's Palsy Symptoms

    Science.gov (United States)

    ... Stories Español Eye Health / Eye Health A-Z Bell's Palsy Sections What Is Bell's Palsy? Bell's Palsy Symptoms Bell's Palsy Treatment Bell's Palsy Symptoms Leer en Español: Síntomas de la parálisis ...

  11. Understanding medical symptoms

    DEFF Research Database (Denmark)

    Malterud, Kirsti; Guassora, Ann Dorrit Kristiane; Graungaard, Anette Hauskov

    2015-01-01

    perspectives deal with how symptom perception occurs when any kind of altered balance brings forward a bodily attention. Corporeality is brought to explicit awareness and perceived as sensations. Jesper Hoffmeyer’s biosemiotic perspectives provide access to how signs are interpreted to attribute meaning......The aim of this article is to present a conceptual review and analysis of symptom understanding. Subjective bodily sensations occur abundantly in the normal population and dialogues about symptoms take place in a broad range of contexts, not only in the doctor’s office. Our review of symptom...... is a social and relational phenomenon of containment, and regulating the situation where the symptoms originate implies adjusting containment. Discourse analysis, as presented by Jonathan Potter and Margaret Wetherell, provides a tool to notice the subtle ways in which language orders perceptions and how...

  12. Chromium-based metal-organic framework MIL-101 as a highly effective catalyst in plasma for toluene removal

    Science.gov (United States)

    Wu, Junliang; Xia, Qibin; Xiao, Jing; Li, Zhong

    2017-11-01

    Catalytic performance of MIL-101—a type of chromium-based metal-organic frameworks (MOFs)—in a plasma catalysis system for toluene removal was experimentally studied. The MIL-101 was synthesized using a hydrothermal method, and its catalytic performance was compared to two other catalysts, Cr2O3/γ-Al2O3 and γ-Al2O3, in a dielectric barrier discharge (DBD) reactor. Results showed that the presence of a catalyst in plasma changed the voltage and current characteristic substantially, and promoted the performance of the plasma reactor. Among the catalysts, the MIL-101 exhibited a significantly high toluene conversion, which was 20% and 35% higher than Cr2O3/γ-Al2O3 and γ-Al2O3, respectively, under the same testing conditions, as well as higher carbon balance and CO2 selectivity. The analysis of by-products on the surfaces of the catalysts before and after reaction demonstrated that MIL-101 had better resistance towards by-products accumulation compared to Cr2O3/γ-Al2O3 and γ-Al2O3. The loading of MnO x on MIL-101 further promoted its catalytic performance. MIL-101 exhibits attractive catalytic properties as a catalyst in a plasma catalysis system for the decomposition of volatile organic compounds.

  13. Chromium-based metal-organic framework MIL-101 as a highly effective catalyst in plasma for toluene removal

    International Nuclear Information System (INIS)

    Wu, Junliang; Xia, Qibin; Xiao, Jing; Li, Zhong

    2017-01-01

    Catalytic performance of MIL-101—a type of chromium-based metal-organic frameworks (MOFs)—in a plasma catalysis system for toluene removal was experimentally studied. The MIL-101 was synthesized using a hydrothermal method, and its catalytic performance was compared to two other catalysts, Cr 2 O 3 / γ -Al 2 O 3 and γ -Al 2 O 3 , in a dielectric barrier discharge (DBD) reactor. Results showed that the presence of a catalyst in plasma changed the voltage and current characteristic substantially, and promoted the performance of the plasma reactor. Among the catalysts, the MIL-101 exhibited a significantly high toluene conversion, which was 20% and 35% higher than Cr 2 O 3 / γ -Al 2 O 3 and γ -Al 2 O 3 , respectively, under the same testing conditions, as well as higher carbon balance and CO 2 selectivity. The analysis of by-products on the surfaces of the catalysts before and after reaction demonstrated that MIL-101 had better resistance towards by-products accumulation compared to Cr 2 O 3 / γ -Al 2 O 3 and γ -Al 2 O 3 . The loading of MnO x on MIL-101 further promoted its catalytic performance. MIL-101 exhibits attractive catalytic properties as a catalyst in a plasma catalysis system for the decomposition of volatile organic compounds. (paper)

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

    International Nuclear Information System (INIS)

    Ju, L.C.; Wan Azelee Wan Abu Bakar; Rusmidah Ali

    2012-01-01

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

  15. Experimental study of Iranian heavy crude oil viscosity reduction by diluting with heptane, methanol, toluene, gas condensate and naphtha

    Directory of Open Access Journals (Sweden)

    Amir Hossein Saeedi Dehaghani

    2016-12-01

    Full Text Available Due to the high viscosity of heavy crude oils, production from these reservoirs is a demanding task. To tackle this problem, reducing oil viscosity is a promising approach. There are various methods to reduce viscosity of heavy oil: heating, diluting, emulsification, and core annular flow. In this study, dilution approach was employed, using industrial solvents and gas condensate. The viscosity of two Iranian heavy crude oils was measured by mixing with solvents at different temperatures. Dilution of both oil samples with toluene and heptane, resulted in viscosity reduction. However, their effect became less significant at higher concentrations of diluent. Because of forming hydrogen bonds, adding methanol to heavy crude oil resulted in higher viscosity. By adding condensate, viscosity of each sample reduced. Gas condensate had a greater impact on heavier oil; however, at higher temperatures its effect was reduced. Diluting with naphtha decreased heavy oil viscosity in the same way as n-heptane and toluene. Besides experimental investigation, different viscosity models were evaluated for prediction of heavy oil/solvent viscosity. It was recognized that Lederer' model is the best one.

  16. Kinetic isotope effects as probes of the mechanism of reaction of 1-naphthylcarbene with cyclohexane and toluene

    International Nuclear Information System (INIS)

    Griffin, G.W.; Horn, K.A.

    1987-01-01

    The rates of reaction of 1-naphthylcarbene (1-NC) in hydrocarbon solution have been measured with excimer laser flash photolysis of 1-naphthyldiazomethane. The kinetic data were obtained by monitoring the growth of the 1-naphthylmethyl radical (1-NCH) at 370 nm. The observed kinetic deuterium isotope effect for the reaction of 1-NC with cyclohexane (cyclohexane-d 12 ) in 2,2,4-trimethylpentane (k/sub H//k/sub D/ = 1.32 +/- 0.17) and the high CH insertion to H-atom abstraction product ratio are consistent with largely singlet reactivity for 1-NC. In toluene, where addition to the aromatic ring is favored over hydrogen atom abstraction, the measured inverse isotope effect (k/sub H//k/sub D/ = 0.52 +/- 0.05) also argues for predominantly singlet reactivity and a small singlet-triplet energy gap. The Arrhenius activation parameters measured for the reaction of NC with cyclohexane and toluene were E/sub act/ = 2.43 +/- 0.19 kcal/mol, log (a, s -1 ) = 7.70 +/- 0.15 and E/sub act/ = 1.93 +/- 0.38 kcal/mol, log (A, s -1 ) = 7.28 +/- 0.30, respectively

  17. 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

  18. Measurement of Soret coefficients in a ternary mixture of toluene-methanol-cyclohexane in convection-free environment

    Science.gov (United States)

    Mialdun, A.; Ryzhkov, I.; Khlybov, O.; Lyubimova, T.; Shevtsova, V.

    2018-01-01

    We report on the measurement of Soret (ST) coefficients in the ternary system toluene (T)-methanol (M)-cyclohexane (Ch) onboard the International Space Station in the experiment selectable optical diagnostic instrument/DCMIX2 (Diffusion Coefficients Measurement in ternary mIXtures). Nine experiments were conducted in the range of mean temperatures between 298.15 K and 306.15 K in the mixture with composition 0.62 (T)-0.31 (M)-0.07 (Ch) in mass fractions. A linear dependence of the Soret coefficients on temperature was established for the ternary mixture. It has also been found that, over considered range of mean temperatures, the Soret coefficients of toluene are small and positive, while the Soret coefficients for methanol are negative and, at least, two times larger. The present work also presents a comprehensive study of possible methodologies to process raw data from the Soret experiment in ternary mixtures. All the experiments were processed by seven different schemes and two of them were identified as the most reliable. We also investigate the error propagation and explain the reasons for the discrepancy of the results obtained by different schemes.

  19. Toluene and chlorobenzene dinitration over solid H3PO4/MoO3/SiO2 catalyst

    International Nuclear Information System (INIS)

    Adamiak, Joanna; Kalinowska-Alichnewicz, Dorota; Szadkowski, Michal; Skupinski, Wincenty

    2011-01-01

    Highlights: → A novel catalyst H 3 PO 4 /MoO 3 /SiO 2 was characterized and used in nitration. → On the surface domains of phosphomolybdic acid (HPM) are obtained. → Dinitrotoluene is obtained with very high yield i.e. 96 wt.% in mild conditions. → Dinitrochlorobenzene is obtained with only twelve-fold excess of nitric acid. → It is sulfuric acid free and solvent free nitration of aromatic compounds. - Abstract: A new catalyst, H 3 PO 4 /MoO 3 /SiO 2 , was prepared by modification of MoO 3 /SiO 2 using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds.

  20. Toluene and chlorobenzene dinitration over solid H3PO4/MoO3/SiO2 catalyst.

    Science.gov (United States)

    Adamiak, Joanna; Kalinowska-Alichnewicz, Dorota; Szadkowski, Michał; Skupiński, Wincenty

    2011-11-15

    A new catalyst, H(3)PO(4)/MoO(3)/SiO(2), was prepared by modification of MoO(3)/SiO(2) using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface. The suitability of the catalysts for toluene and chlorobenzene nitration in continuous process was examined. Toluene is effectively nitrated to dinitrotoluene (DNT) in one-stage process (96 wt.% of DNT in the product) and in mild conditions i.e. at room temperature and only with ten-fold excess of nitric acid. In chlorobenzene nitration only twelve-fold excess of nitric acid is needed to obtain as high yield as 95 wt.%. Most importantly, the novel catalysts we have developed, provide the opportunity for sulfuric acid- free nitration of aromatic compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Non-hydrolytic formation of silica and polysilsesquioxane particles from alkoxysilane monomers with formic acid in toluene/tetrahydrofuran solutions

    Science.gov (United States)

    Boday, Dylan J.; Tolbert, Stephanie; Keller, Michael W.; Li, Zhe; Wertz, Jason T.; Muriithi, Beatrice; Loy, Douglas A.

    2014-03-01

    Silica and polysilsesquioxane particles are used as fillers in composites, catalyst supports, chromatographic separations media, and even as additives to cosmetics. The particles are generally prepared by hydrolysis and condensation of tetraalkoxysilanes and/or organotrialkoxysilanes, respectively, in aqueous alcohol solutions. In this study, we have discovered a new, non-aqueous approach to prepare silica and polysilsesquioxane particles. Spherical, nearly monodisperse, silica particles (600-6,000 nm) were prepared from the reaction of tetramethoxysilane with formic acid (4-8 equivalents) in toluene or toluene/tetrahydrofuran solutions. Polymerization of organotrialkoxysilanes with formic acid failed to afford particles, but bridged polysilsesquioxane particles were obtained from monomers with two trialkoxysilyl group attached to an organic-bridging group. The mild acidic conditions allowed particles to be prepared from monomers, such as bis(3-triethoxysilylpropyl)tetrasulfide, which are unstable to Stöber or base-catalyzed emulsion polymerization conditions. The bridged polysilsesquioxane particles were generally less spherical and more polydisperse than silica particles. Both silica and bridged polysilsesquioxane nanoparticles could be prepared in good yields at monomer concentrations considerably higher than used in Stöber or emulsion approaches.

  2. Efficient removal of toluene and benzene in gas phase by the TiO2/Y-zeolite hybrid photocatalyst.

    Science.gov (United States)

    Takeuchi, Masato; Hidaka, Manabu; Anpo, Masakazu

    2012-10-30

    Efficient removal of toluene or benzene molecules thinly diffused in gas phase was achieved by using TiO(2)/Y-zeolite hybrid photocatalysts. TiO(2) of 10 wt% hybridized with a hydrophobic USY zeolite showed higher photocatalytic reactivity as compared to TiO(2) hybridized with hydrophilic H-Y or Na-Y zeolites. This phenomenon can be explained by the fact that the hydrophobic USY zeolite efficiently adsorbs the organic compounds and smoothly supplies them onto the TiO(2) photocatalyst surface. However, the toluene or benzene molecules, which are strongly trapped on the hydrophilic H(+) or Na(+) sites of zeolite, cannot diffuse onto the TiO(2) surfaces, resulting in lower photocatalytic reactivity. Although the adsorption capacity of the pure TiO(2) sample rapidly deteriorated, the TiO(2)/Y-zeolite hybrid system maintained a high adsorption efficiency to remove such aromatic compounds for a long period. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. [Microwave In-situ Regeneration of Cu-Mn-Ce/ZSM Catalyst Adsorbed Toluene and Distribution of Bed Temperature].

    Science.gov (United States)

    Hu, Xue-jiao; Bo, Long-li; Liang, Xin-xin; Meng, Hai-long

    2015-08-01

    Microwave in-situ regeneration of Cu-Mn-Ce/ZSM catalyst adsorbed toluene, distribution of fixed bed temperature, adsorption breakthrough curves of the catalyst after several regenerations and characterizations of the catalyst by BET and SEM were investigated in this study. The research indicated that regeneration effect of the catalyst adsorbed was excellent under conditions of microwave power 117 W, air flow 0.5 m3 x h(-1) and catalyst dosage of 800 g. Toluene desorbed was oxidized onto the surface of the catalyst, and the adsorption capacity of the catalyst was recovered simultaneously. Under microwave irradiation, bed temperature decreased slowly from inside to outside in horizontal level, and increased gradually from down to up in vertical level so that the highest temperature reached 250-350 degrees C at the upper sites of the bed. Sintering and agglomeration occurred on the surface of the catalyst in the course of regeneration so that the special surface area and micropore volume of the catalyst were reduced and breakthrough time was shortened, which was verified by six adsorption breakthrough curves and related characteristics of the catalyst. However, the structure of the catalyst was steady after two regenerations, and adsorption breakthrough time was kept at 70 min. The result showed that the changes of surface morphology and pore structure were positively correlated with the distribution of bed temperature.

  4. The IR spectra and hydrogen bonding of toluene-2,6-bis(methyl) and 4,4'-diphenylmethane-bis(methyl) carbamates

    Science.gov (United States)

    Furer, V. L.

    2000-03-01

    The IR spectroscopy has been used to study models of polyurethanes containing different hard segments. The spectra of toluene-2,6-bis(methyl) and 4,4'-diphenylmethane-bis(methyl) carbamates at different temperatures were studied. The absorption curves of the free and associated carbamate molecules were compared with experimental IR spectra. The characteristic features of toluene-2,6-bis(methyl) carbamate and methyl- N-methyl carbamate clusters were revealed. The IR spectra for the two most stable toluene-2,6-bis(methyl) carbamate conformations were compared. The origin of the multiplet structure of bands in the experimental IR spectra of polyurethanes was discussed. The results obtained can be used for the analysis of the chemical and physical transformations in urethanes and polyurethanes.

  5. Synthesis of quaternary derivatives of ortho-coco di-amido toluene and investigation of these compounds as cationic bitumen emulsifier

    Energy Technology Data Exchange (ETDEWEB)

    Hassanzadeh, Masoumeh; Tayebi, Leila; Dezfouli, Hedieh; Kambarani, Masoud; Avval, Parviz Ahmadi [Tehran Univ. (Iran, Islamic Republic of). ACECR, Designing Chemical Process Research Group

    2012-05-15

    Bitumen emulsions are preferred over conventional pavement systems due to their biologically and environmentally acceptable formulation, safety, low viscosity, storage stability, and cost effectiveness. The present investigation deals with the systematic study to synthesize ortho-cocodi-amido toluene and four quaternary derivatives by amidation of coconut oil and ortho toluene diamine (OTD), followed by quaternization with formaldehyde, formic acid mixture, and acrylonitrile, resulted in a new quaternary compound useful as cationic emulsifier in bitumen emulsions. The roles of temperature and reaction time in determining optimum conditions were investigated as well. Emulsifying behavior of these quaternary compounds was studied by sieve residue test, settlement and storage stability test of emulsified asphalt, and water solubility. The results show that the acrylonitrile imidazolinium derivative of o-cocodi-amido toluene (VI) can be used as a rapid-medium setting emulsifier. (orig.)

  6. THE ROLE OF IRON IN Deinococcus radiodurans ENGINEERED FOR GROWTH ON TOLUENE AND THE ROLE OF MANGANESE IN THE EXTREME RADIATION RESISTANCE PHENOTYPE

    Energy Technology Data Exchange (ETDEWEB)

    Hassan Brim; Elena K. Gaidamakova; Vera Y. Matrosova; Min Zhai; Amudhan Venkateswaran; Marina Omelchenko; Kira S. Makarova; Lawrence P. Wackett; James K. Fredrickson; Michael J. Daly

    2004-03-17

    Toluene and other fuel hydrocarbons are commonly found in association with radionuclides at numerous Department of Energy (DOE) sites, frequently occurring together with Cr(VI) and other heavy metals. In this study, the extremely radiation resistant bacterium Deinococcus radiodurans was engineered for complete toluene mineralization by cloned expression of tod and xyl genes of Pseudomonas putida. The recombinant Tod/Xyl strain showed significant incorporation of carbon from the toluene aromatic ring into cellular macromolecules and carbon dioxide, in the absence or presence of chronic radiation. We have shown that intracellular iron concentrations in wild-type D. radiodurans in minimal medium are exceptionally low and not sufficient to support growth on toluene using Fe-dependent oxygenases cloned from P. putida. Introducing the fur mutation into D. radiodurans increased intracellular Fe levels, and imparted on the engineered strain the ability to grow on meta-toluate as the sole carbon and energy source. The organism's native Cr(VI) reduction capabilities were facilitated by toluene when present as the sole carbon and energy source in natural sediment analogues of DOE contaminated environments. The engineered bacteria were able to oxidize toluene under both minimal and complex nutrient conditions, which is important since both conditions have environmental equivalents in the context of bioremediation processes. As such, the Tod/Xyl strain is providing a model for understanding the role of Fe and reduction of metals coupled to organic contaminant oxidation in aerobic radionuclide contaminated sediments. We have shown that D. radiodurans contains high intracellular manganese levels, and that Mn restriction sensitizes cells to irradiation. We propose that the unusually high Mn/Fe ratio of D. radiodurans facilitates survival by quenching oxidative stress during recovery.

  7. The Genome of the Toluene-Degrading Pseudomonas veronii Strain 1YdBTEX2 and Its Differential Gene Expression in Contaminated Sand.

    Directory of Open Access Journals (Sweden)

    Marian Morales

    Full Text Available The natural restoration of soils polluted by aromatic hydrocarbons such as benzene, toluene, ethylbenzene and m- and p-xylene (BTEX may be accelerated by inoculation of specific biodegraders (bioaugmentation. Bioaugmentation mainly involves introducing bacteria that deploy their metabolic properties and adaptation potential to survive and propagate in the contaminated environment by degrading the pollutant. In order to better understand the adaptive response of cells during a transition to contaminated material, we analyzed here the genome and short-term (1 h changes in genome-wide gene expression of the BTEX-degrading bacterium Pseudomonas veronii 1YdBTEX2 in non-sterile soil and liquid medium, both in presence or absence of toluene. We obtained a gapless genome sequence of P. veronii 1YdBTEX2 covering three individual replicons with a total size of 8 Mb, two of which are largely unrelated to current known bacterial replicons. One-hour exposure to toluene, both in soil and liquid, triggered massive transcription (up to 208-fold induction of multiple gene clusters, such as toluene degradation pathway(s, chemotaxis and toluene efflux pumps. This clearly underlines their key role in the adaptive response to toluene. In comparison to liquid medium, cells in soil drastically changed expression of genes involved in membrane functioning (e.g., lipid composition, lipid metabolism, cell fatty acid synthesis, osmotic stress response (e.g., polyamine or trehalose synthesis, uptake of potassium and putrescine metabolism, highlighting the immediate response mechanisms of P. veronii 1YdBTEX2 for successful establishment in polluted soil.

  8. THE ROLE OF IRON IN Deinococcus radiodurans ENGINEERED FOR GROWTH ON TOLUENE AND THE ROLE OF MANGANESE IN THE EXTREME RADIATION RESISTANCE PHENOTYPE

    International Nuclear Information System (INIS)

    Hassan Brim; Elena K. Gaidamakova; Vera Y. Matrosova; Min Zhai; Amudhan Venkateswaran; Marina Omelchenko; Kira S. Makarova; Lawrence P. Wackett; James K. Fredrickson; Michael J. Daly

    2004-01-01

    Toluene and other fuel hydrocarbons are commonly found in association with radionuclides at numerous Department of Energy (DOE) sites, frequently occurring together with Cr(VI) and other heavy metals. In this study, the extremely radiation resistant bacterium Deinococcus radiodurans was engineered for complete toluene mineralization by cloned expression of tod and xyl genes of Pseudomonas putida. The recombinant Tod/Xyl strain showed significant incorporation of carbon from the toluene aromatic ring into cellular macromolecules and carbon dioxide, in the absence or presence of chronic radiation. We have shown that intracellular iron concentrations in wild-type D. radiodurans in minimal medium are exceptionally low and not sufficient to support growth on toluene using Fe-dependent oxygenases cloned from P. putida. Introducing the fur mutation into D. radiodurans increased intracellular Fe levels, and imparted on the engineered strain the ability to grow on meta-toluate as the sole carbon and energy source. The organism's native Cr(VI) reduction capabilities were facilitated by toluene when present as the sole carbon and energy source in natural sediment analogues of DOE contaminated environments. The engineered bacteria were able to oxidize toluene under both minimal and complex nutrient conditions, which is important since both conditions have environmental equivalents in the context of bioremediation processes. As such, the Tod/Xyl strain is providing a model for understanding the role of Fe and reduction of metals coupled to organic contaminant oxidation in aerobic radionuclide contaminated sediments. We have shown that D. radiodurans contains high intracellular manganese levels, and that Mn restriction sensitizes cells to irradiation. We propose that the unusually high Mn/Fe ratio of D. radiodurans facilitates survival by quenching oxidative stress during recovery.

  9. Toluene diisocyanate emission to air and migration to a surface from a flexible polyurethane foam.

    Science.gov (United States)

    Vangronsveld, Erik; Berckmans, Steven; Spence, Mark

    2013-06-01

    Flexible polyurethane foam (FPF) is produced from the reaction of toluene diisocyanate (TDI) and polyols. Because of the potential for respiratory sensitization following exposure to TDI, concerns have been raised about potential consumer exposure to TDI from residual 'free TDI' in FPF products. Limited and conflicting results exist in the literature concerning the presence of unreacted TDI remaining in FPF as determined by various solvent extraction and analysis techniques. Because residual TDI results are most often intended for application in assessment of potential human exposure to TDI from FPF products, testing techniques that more accurately simulated human contact with foam were designed. To represent inhalation exposure to TDI from polyurethane foam, a test that measured the emission of TDI to air was conducted. For simulation of human dermal exposure to TDI from polyurethane foam, a migration test technique was designed. Emission of TDI to air was determined for a representative FPF using three different emission test cells. Two were commercially available cells that employ air flow over the surface of the foam [the Field and Laboratory Emission Cell (FLEC®) and the Micro-Chamber/Thermal Extraction™ cell]. The third emission test cell was of a custom design and features air flow through the foam sample rather than over the foam surface. Emitted TDI in the air of the test cells was trapped using glass fiber filters coated with 1-(2-methoxyphenyl)-piperazine (MP), a commonly used derivatizing agent for diisocyanates. The filters were subsequently desorbed and analyzed by liquid chromatography/mass spectrometry. Measurement of TDI migration from representative foam was accomplished by placing glass fiber filters coated with MP on the outer surfaces of a foam disk and then compressing the filters against the disk using a clamping apparatus for periods of 8 and 24 h. The sample filters were subsequently desorbed and analyzed in the same manner as for the

  10. Fibromyalgia symptoms and cirrhosis.

    Science.gov (United States)

    Rogal, Shari S; Bielefeldt, Klaus; Wasan, Ajay D; Szigethy, Eva; Lotrich, Francis; DiMartini, Andrea F

    2015-05-01

    An association between fibromyalgia and hepatitis C virus (HCV) has been previously described. However, the relationship between nonalcoholic steatohepatitis (NASH) and fibromyalgia symptoms has not been assessed, though they share several risk factors. We aimed to assess the factors associated with fibromyalgia symptoms across etiologies of liver disease. Patients with cirrhosis due to HCV, NASH, or alcohol were recruited from an outpatient hepatology clinic and administered the Hospital Anxiety and Depression Score, Pittsburgh Sleep Quality Index, and the modified 2010 American College of Rheumatology Diagnostic Criteria for Fibromyalgia. Serum inflammatory markers were measured with standard luminex assays. Of 193 participants, 53 (27 %) met criteria for fibromyalgia. Fibromyalgia symptoms were significantly associated with etiology of liver disease (HCV: 35 %, NASH: 30 %, alcohol-related liver disease: 12 %, p etiology of liver disease (NASH vs. HCV not different, alcohol vs. HCV OR 0.19, 95 % CI 0.05, 0.63) were associated with fibromyalgia symptoms. If abdominal pain was included in the model, etiology became nonsignificant, indicating that it may be central sensitization due to abdominal pain in patients with chronic liver disease that explains fibromyalgia symptoms rather than the etiology of liver disease or inflammation. Fibromyalgia symptoms were significantly associated with HCV and NASH cirrhosis and with psychiatric symptoms. Future work should focus on the underlying pathophysiology and management of widespread pain in patients with cirrhosis.

  11. Synthesis and evaluation of novel biochar-based and metal oxide-based catalysts for removal of model tar (toluene), ammonia, and hydrogen sulfide from simulated producer gas

    Science.gov (United States)

    Bhandari, Pushpak

    Gasification is a thermochemical conversion process in which carbonaceous feedstock is gasified in a controlled atmosphere to generate producer gas. The producer gas is used for production of heat, power, fuels and chemicals. Various contaminants such as tars, NH3, and H2S in producer gas possess many problems due to their corrosive nature and their ability to clog and deactivate catalysts. In this study, several catalysts were synthesized, characterized, and tested for removal of three contaminants (toluene (model tar), NH3, and H2S) from the biomass-generated producer gas. Biochar, a catalyst, was generated from gasification of switchgrass. Activated carbon and acidic surface activated carbon were synthesized using ultrasonication method from biochar. Acidic surface was synthesized by coating activated carbon with dilute acid. Mixed metal oxide catalysts were synthesized from hydrotalcite precursors using novel synthesis technique using microwave and ultrasonication. Surface area of activated carbon (˜900 m2/g) was significantly higher than that of its precursor biochar (˜60 m2/g). Surface area of metal oxide catalyst was approximately 180 m2/g after calcination. Biochar, activated carbon, and acidic surface activated carbon showed toluene removal efficiencies of approximately 78, 88, and 88 %, respectively, when the catalysts were tested individually with toluene in the presence of producer gas at 800 °C. The toluene removal efficiencies increased to 86, 91, and 97 % using biochar, activated carbon and acidic surface activated carbon, respectively in the presence of NH3 and H2S in the producer gas. Increase in toluene removal efficiencies in presence of NH3 and H2S indicates that NH3 and H 2S play a role in toluene reforming reactions during simultaneous removal of contaminants. Toluene removal efficiency for mixed metal oxide was approximately 83%. Ammonia adsorption capacities were 0.008 g NH3/g catalyst for biochar and 0.03g NH3/g catalyst for activated

  12. Effects of HCl and HNO3 on the oxidation of toluene to benzaldehyde by H2O2 over TS-1 modified with Al in aqueous phase

    Directory of Open Access Journals (Sweden)

    Paricha Pongjirawat

    2014-09-01

    Full Text Available This research studies effects of HCl and HNO3 in aqueous solution on the oxidation reaction between toluene and hydrogen peroxide to benzaldehyde over titanium silicalite-1 catalyst modified with Al. The reaction was carried out at reaction temperature 120°C in a pressurized autoclave reactor. The research found that the addition of HCl and HNO3 not only increases the concentration of toluene in the aqueous phase but also increases the formation of benzaldehyde as main product in the reaction.

  13. Summary report on the aerobic degradation of diesel fuel and the degradation of toluene under aerobic, denitrifying and sulfate reducing conditions

    International Nuclear Information System (INIS)

    Coyne, P.; Smith, G.

    1995-01-01

    This report contains a number of studies that were performed to better understand the technology of the biodegradation of petroleum hydrocarbons. Topics of investigation include the following: diesel fuel degradation by Rhodococcus erythropolis; BTEX degradation by soil isolates; aerobic degradation of diesel fuel-respirometry; aerobic degradation of diesel fuel-shake culture; aerobic toluene degradation by A3; effect of HEPES, B1, and myo-inositol addition on the growth of A3; aerobic and anaerobic toluene degradation by contaminated soils; denitrifying bacteria MPNs; sulfate-reducing bacteria MPNs; and aerobic, DNB and SRB enrichments

  14. Complete nucleotide sequence of the self-transmissible TOL plasmid pD2RT provides new insight into arrangement of toluene catabolic plasmids

    DEFF Research Database (Denmark)

    Jutkina, Jekaterina; Hansen, Lars H.; Li, Lili

    2013-01-01

    In the present study we report the complete nucleotide sequence of the toluene catabolic plasmid pD2RT of Pseudomonas migulae strain D2RT isolated from Baltic Sea water. The pD2RT is 129,894 base pairs in size with an average G+ C content of 53.75%. A total of 135 open reading frames (ORFs) were ...... predicted to encode proteins, among them genes for catabolism of toluene, plasmid replication, maintenance and conjugative transfer. ORFs encoding proteins with putative functions in stress response, transposition and site- ...

  15. Liquid–liquid extraction of toluene from alkane with pyridinium based ionic liquid ([BPy][NO3] and [HPy][NO3]) at 298.15 K and atmospheric pressure

    International Nuclear Information System (INIS)

    Enayati, Mobin; Mokhtarani, Babak; Sharifi, Ali; Anvari, Sanam; Mirzaei, Mojtaba

    2016-01-01

    Highlights: • Extraction of toluene from alkane with pyridinium based ionic liquid was studied. • The ionic liquids [BPy][NO 3 ] and [HPy][NO 3 ] were used. • The effect of alkane chain length on selectivity of toluene was evaluated. • The effect of alkyl chain length of ionic liquids on toluene selectivity was investigated. • The experimental data were correlated with the NRTL model. - Abstract: The focus of this paper is to study the liquid−liquid extraction process for the separation of toluene from alkane employing the ionic liquids N-butylpyridinium nitrate, [BPy][NO 3 ], and N-hexylpyridinium nitrate, [HPy][NO 3 ], as a new solvents. New experimental data for the ternary systems of {[BPy][NO 3 ] (1) + heptane, or octane, or decane (2) + toluene (3)} and {[HPy][NO 3 ] (1) + heptane, or octane, or decane (2) + toluene (3)} at T = 298.15 K and atmospheric pressure are reported. The Othmer-Tobias and Hand correlation are examined to check the reliability of the experimental LLE data. The toluene distribution ratios and selectivity were calculated form the experimental data. The selectivity values are higher than unity which indicates the ILs, [BPy][NO 3 ] and [HPy][NO 3 ], used in this work are potential solvents to separate toluene from alkane. Besides, the effect of the alkane chain length in the selectivity values was evaluated. In addition, the result of the NRTL thermodynamic modeling shows, the experimental data were satisfactorily correlated.

  16. Premonitory symptoms in migraine

    DEFF Research Database (Denmark)

    Laurell, Katarina; Artto, Ville; Bendtsen, Lars

    2016-01-01

    AIM: To describe the frequency and number of premonitory symptoms (PS) in migraine, the co-occurrence of different PS, and their association with migraine-related factors. METHODS: In this cross-sectional study, a validated questionnaire was sent to Finnish migraine families between 2002 and 2013...... to obtain data on 14 predefined PS, migraine diagnoses, demographic factors, and migraine characteristics. The estimated response rate was 80%. RESULTS: Out of 2714 persons, 2223 were diagnosed with migraine. Among these, 77% reported PS, with a mean number of 3.0 symptoms compared to 30% (p ....5 symptoms (p migraine headaches. Yawning was the most commonly reported symptom (34%) among migraineurs. Females reported PS more frequently than males (81 versus 64%, p 

  17. Dyslexia: Causes, Symptoms, Definition.

    Science.gov (United States)

    Shannon, Albert J.

    1986-01-01

    The article reviews proposed causes and observable symptoms that characterize dyslexia, concluding that individualized analysis and specialized treatments are required and that, until an operational definition can be agreed upon, use of the label "dyslexia" is counterproductive. (DB)

  18. Chiari Malformation: Symptoms

    Science.gov (United States)

    ... hearing, vomiting, double vision, vision loss, blackouts, apnea, vertigo, loss of peripheral vision, nystagmus, earache, snoring, thoracic pain, hypotension, wake up choking, leg pain, palpitations, hypertension, gag reflex, and face pain/tingling. Symptom Headache ...

  19. Social sensations of symptoms

    DEFF Research Database (Denmark)

    Meinert, Lotte; Whyte, Susan Reynolds

    2017-01-01

    The interpretation of sensations and the recognition of symptoms of a sickness, as well as the movement to seek treatment, have long been recognised in medical anthropology as inherently social processes. Based on cases of HIV and trauma (PTSD) in Uganda, we show that even the first signs...... and sensations of sickness can be radically social. The sensing body can be a ‘social body’ – a family, a couple, a network – a unit that transcends the individual body. In this article, we focus on four aspects of the sociality of sensations and symptoms: mode of transmission, the shared experience...... of sensations/symptoms, differential recognition of symptoms, and the embodied sociality of treatment....

  20. Symptoms of Blood Disorders

    Science.gov (United States)

    ... Abbreviations Weights & Measures ENGLISH View Professional English Deutsch Japanese Espaniol Find information on medical topics, symptoms, drugs, ... sample? Analysis of cell surface proteins Chromosomal analysis Cultures for bacteria Determination of the original arrangement of ...

  1. Giardia: Illness & Symptoms

    Science.gov (United States)

    ... Illness & Symptoms Recommend on Facebook Tweet Share Compartir Giardia trophozoites stained with trichrome. Credit: Waterborne Disease Prevention Branch, CDC Giardiasis is the most frequently diagnosed intestinal parasitic disease in the United States and among ...

  2. Cholera Illness and Symptoms

    Science.gov (United States)

    ... Search The CDC Cancel Submit Search The CDC Cholera - Vibrio cholerae infection Note: Javascript is disabled or ... message, please visit this page: About CDC.gov . Cholera General Information Illness & Symptoms Sources of Infection & Risk ...

  3. Symptoms of Tickborne Illness

    Science.gov (United States)

    ... and experience any of the symptoms described here. "Target" lesion on patient with Lyme disease. Patient with ... Word file Microsoft Excel file Audio/Video file Apple Quicktime file RealPlayer file Text file Zip Archive ...

  4. Symptoms and Diagnosis

    Science.gov (United States)

    ... Special Events Faces of Dystonia Donate Donate Online Membership Find an Event Donor Bill of Rights About Dystonia Symptoms & Diagnosis Forms of Dystonia Genetics Glossary Treatment Find a Doctor Oral Medications Botulinum Neurotoxin Neurosurgery ...

  5. Gynecological cancer alarm symptoms:

    DEFF Research Database (Denmark)

    Balasubramaniam, Kirubakaran; Ravn, Pernille; dePont Christensen, René

    2016-01-01

    INTRODUCTION: To determine the proportion of patients who were referred to specialist care after reporting gynecological cancer alarm symptoms to their general practitioner. To investigate whether contact with specialist care was associated with lifestyle factors or socioeconomic status. MATERIAL...... and odds ratios (ORs) for associations between specialist care contact, lifestyle factors and socioeconomic status. RESULTS: The study included 25 866 non-pregnant women; 2957 reported the onset of at least one gynecological cancer alarm symptom, and 683 of these (23.1%) reported symptoms to their general......: Educational level influence contact with specialist care among patients with gynecological cancer alarm symptoms. Future studies should investigate inequalities in access to the secondary healthcare system. This article is protected by copyright. All rights reserved....

  6. Dermatomyositis: Signs and Symptoms

    Science.gov (United States)

    ... for MDA Blog Donate Search MDA.org Close Dermatomyositis Share print email share facebook twitter google plus ... Signs and Symptoms What happens to someone with dermatomyositis? For many decades, dermatomyositis was considered “ polymyositis with ...

  7. Glaucoma: Symptoms, Diagnosis & Treatment

    Science.gov (United States)

    ... and silently clouds vision, without any pain. Photo courtesy of NEI Glaucoma Symptoms At first, open-angle ... steady rate for up to a month. Photo courtesy of: Peter Mallen, Massachusetts Eye and Ear Laboratory/ ...

  8. Medically Unexplained Symptoms

    Science.gov (United States)

    ... may flare up or worsen. IRRITABLE BOWEL SYNDROME Irritable Bowel Syndrome (IBS) is an MUS that interferes with the normal functioning of the large intestine. It is characterized by a group of symptoms, ...

  9. Prostate Cancer Symptoms

    Science.gov (United States)

    ... Fundraise for PCF: Many vs Cancer Contact Us Prostate Cancer Symptoms and Signs Prostate Cancer Basics About the ... earlier. So what are the warning signs of prostate cancer? Unfortunately, there usually aren’t any early warning ...

  10. Cocaine and Psychiatric Symptoms.

    Science.gov (United States)

    Morton, W Alexander

    1999-08-01

    BACKGROUND: Cocaine is an addictive drug that produces numerous psychiatric symptoms, syndromes, and disorders. The symptoms include agitation, paranoia, hallucinations, delusions, violence, as well as suicidal and homicidal thinking. They can be primary to the drug's effect or secondary to exacerbation of comorbid psychiatric disorders. DATA SOURCES: A computerized literature search was conducted using MEDLINE to identify reports of psychiatric symptoms secondary to cocaine use. Additional reports were found via bibliographies of various published reports. DATA SYNTHESIS: The use of cocaine in the "crack" form is often associated with more frequent and intense symptoms. Paranoia occurs in 68% to 84% of patients using cocaine. Cocaine-related violent behaviors occur in as many as 55% of patients with cocaine-induced psychiatric symptoms. Homicide has also been associated with cocaine use in as many as 31% of homicide victims. In suicide, cocaine has been found to be present in as high as 18% to 22% of cases. Many patients with cocaine dependence have also been found to have a comorbid psychiatric disorder. CONCLUSION: Cocaine can produce a spectrum of psychiatric symptoms with which primary care practitioners need to be familiar. Comorbid psychiatric disorders are frequent in patients with cocaine use disorders and can worsen with cocaine use. Nonaddictive medication may be necessary to treat comorbid conditions such as anxiety and depressive disorders. Primary care practitioners need to be familiar with the treatment programs for patients with cocaine use disorders so appropriate referral can easily take place and follow-up care can be understood and maintained.

  11. Simulation of SOA formation and composition from oxidation of toluene and m-xylene in chamber experiments

    Science.gov (United States)

    Xu, J.; Liu, Y.; Nakao, S.; Cocker, D.; Griffin, R. J.

    2013-12-01

    Aromatic hydrocarbons contribute an important fraction of anthropogenic reactive volatile organic compounds (VOCs) in the urban atmosphere. Photo-oxidation of aromatic hydrocarbons leads to secondary organic products that have decreased volatilities or increased solubilities and can form secondary organic aerosol (SOA). Despite the crucial role of aromatic-derived SOA in deteriorating air quality and harming human health, its formation mechanism is not well understood and model simulation of SOA formation still remains difficult. The dependence of aromatic SOA formation on nitrogen oxides (NOx) is not captured fully by most SOA formation models. Most models predict SOA formation under high NOx levels well but underestimate SOA formation under low NOx levels more representative of the ambient atmosphere. Thus, it is crucial to investigate the NOx-dependent chemistry in aromatic photo-oxidation systems and correspondingly update SOA formation models. In this study, NOx-dependent mechanisms of toluene and m-xylene SOA formation are updated using the gas-phase Caltech Atmospheric Chemistry Mechanism (CACM) coupled to a gas/aerosol partitioning model. The updated models were optimized by comparing to eighteen University of California, Riverside United States Environmental Protection Agency (EPA) chamber experiment runs under both high and low NOx conditions. Correction factors for vapor pressures imply uncharacterized aerosol-phase association chemistry. Simulated SOA speciation implies the importance of ring-opening products in governing SOA formation (up to 40%~60% for both aromatics). The newly developed model can predict strong decreases of m-xylene SOA yield with increasing NOx. Speciation distributions under varied NOx levels implies that the well-known competition between RO2 + HO2 and RO2 + NO (RO2 = peroxide bicyclic radical) may not be the only factor influencing SOA formation. The reaction of aromatic peroxy radicals with NO competing with its self

  12. Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

    Science.gov (United States)

    Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

    2018-04-01

    Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.

  13. [Prodromal symptoms of schizophrenia].

    Science.gov (United States)

    Elkhazen, C; Chauchot, F; Canceil, O; Krebs, M-O; Baylé, F-J

    2003-01-01

    The concept of prodromal symptoms of schizophrenia has frequently been subject to debate. Authors widely admit the existence of early specific and non-specific signs preceding the first psychotic episode; however, they have yet to clearly demonstrate their ability to predict and specify the outbreak of a psychosis. These prodromal symptoms consist of behavioral abnormalities, pseudo-neurotic signs, subtle cognitive and affective changes. All these symptoms vary from patient to patient. In general, it is widely believed that future patients go through a variety of abnormal, subjective experiences that progressively develop during their pre-puberty and puberty periods. However, the limit of this assessment is that an individual could present the same prodromal symptoms without necessarily developing a psychotic illness, as a result of toxic intake, a situational crisis, etc. Furthermore, while the prodrome is a retrospective concept, its value and specificity can only be prospective, given that patients' descriptions of pre-morbid changes may be corrupted by inefficient memory reconstruction. DSM III-R included prodromal symptoms; individual presenting such symptoms would potentially present psychopathological vulnerability to psychosis regardless of associated genetic risk. Several investigations have shed doubts on their measurement's reliability; therefore, this classification is no longer present in the latest version (DSM IV). Moreover, recent neurodevelopemental hypothesis on schizophrenia have paved the way for possible early intervention, especially because early treatments could well improve illness prognosis. This viewpoint is reinforced by the improved tolerance of new anti-psychotic treatment. In this report, we review the key Articles published over the last 15 Years on this matter. We distinguish two schools of thought: on one hand, the German school referring to the validity of particular neuro-psychological symptoms: attention, perception

  14. Porous Epoxy: Effect of Mixing Sequences (ELH versus EHL Using Toluene as Extraction Medium via Ultrasonic Technique

    Directory of Open Access Journals (Sweden)

    Siti Noorkhartina Ishak

    2016-01-01

    Full Text Available Porous epoxy was fabricated using natural rubber latex (NRL as the void template. In this study, two mixing sequences were selected: epoxy, hardener, and then latex (EHL and epoxy, latex, and then hardener (ELH. The extraction process was carried out to extract the latex particles from the cured epoxy sample using toluene as extraction medium with ultrasonic technique for 1 hour. The formation of porous structure in epoxy system is dependent essentially on the amount of latex removed from the epoxy matrix. As expected, the density results showed lower values in the porous epoxy in ELH mixing sequences. More porous structure in epoxy was obtained which was proven by the increasing in porosity % which has led to lowering of the value in dielectric constant which is preferred for electronic packaging application. However, it also caused a decrease in flexural strength and modulus.

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

    International Nuclear Information System (INIS)

    Rafati, Amir Abbas; Ghasemian, Ensieh

    2009-01-01

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

  16. A clean method for solvent-free nitration of toluene over sulfated titania promoted by ceria catalysts.

    Science.gov (United States)

    Mao, Wei; Ma, Hongzhu; Wang, Bo

    2009-08-15

    A mild simple method for nitration of aromatic compounds, various solid acids as catalysts, the air treated with the corona discharge generator as nitrating agent, the liquid-phase nitration of toluene, at ambient temperature and atmospheric pressure without solvent has been investigated. The results show that SO(4)(2-)/TiO(2) (ST) and SO(4)(2-)/TiO(2) doped with CeO(2) (STC) catalysts displayed good nitration activity in the experiments. It is an attractive method for the environmentally friendly synthesis of nitroaromatic compounds. Moreover, only mononitrotoluenes were detected in the products, and the ratio of para-nitrotoluene and ortho-nitrotoluene was approximately 1:1 with various catalysts. A maximum yield of about 11.4% was achieved for mononitrotoluenes in STC reaction system in 3h.

  17. N,N,N',N'-tetrabutyladipicamide as a new extractant in toluene of nitric acid and uranium(VI)

    International Nuclear Information System (INIS)

    Wang, Y.S.; Tan, X.F.; Shen, C.H.; Bao, B.R.

    1999-01-01

    N,N,N',N'-Tetrabutyladipicamide (TBAA) was used for the extraction of nitric acid and uranyl(II) ion from nitric acid media into toluene. The effects of nitric acid, uranyl(II) ion, and extractant concentration, temperature and back extraction on the distribution coefficient of uranyl(II) ion have been studied. The main adduct of TBAA and HNO 3 is TBAA-HNO 3 in 1.0 mol/l nitric acid solution. The 1:2:2 complex of uranyl(II) ion, nitrate ion and TBAA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBAA. The values of the thermodynamic parameters have also been calculated. (author)

  18. Effects of combined prenatal stress and toluene exposure on apoptotic neurodegeneration in cerebellum and hippocampus of rats

    DEFF Research Database (Denmark)

    Ladefoged, Ole; Hougaard, Karin Sørig; Hass, Ulla

    2004-01-01

    Pregnant Wistar rats were exposed to 1500 ppm toluene 6 hr/day from gestational day 7-20 or to chronical mild stress from gestational day 9-20 as single exposure or in combination. Behavioural, immunohistopathological, molecular biological, and neurochemical methods were applied to investigate...... the offspring for developmental neurotoxicity and level of apoptosis in the brain. The number of apoptotic cells in cerebellum postnatal day 22, 24, and 27 and in hippocampus (postnatal day 22, 24, and 27) were counted after visualization by the TUNEL staining or measured by DNA-laddering technique. Caspase-3...... activity was determined in cerebellum (postnatal day 6, 22, 24, and 27) and in hippocampus (postnatal day 6 and 22). TUNEL staining and DNA-laddering technique showed a marked decrease in number of apoptotic cells from postnatal day 22 to 27 in both cerebellum and hippocampus. Apparently, a peak...

  19. Comparison of needle concentrator with SPME for GC determination of benzene, toluene, ethylbenzene, and xylenes in aqueous samples

    Energy Technology Data Exchange (ETDEWEB)

    Prikryl, P.; Sevcik, J. [Charles Univ., Prague (Czech Republic). Dept. of Analytical Chemistry; Kubinec, R.; Jurdakova, H.; Ostrovsky, I.; Sojak, L. [Comenius Univ., Bratislava (Slovakia). Chemical Inst.; Berezkin, V. [Russian Academy of Sciences, Moscow (Russian Federation). A.V. Topchiev Inst. of Petrochemical Synthesis

    2006-07-15

    A method of solventless extraction of volatile organic compounds from aqueous samples has been developed and validated. A new arrangement in which the internal volume of a needle capillary adsorption trap is completely filled with Porapak Q, as adsorbent material, and wet alumina, as a source of desorptive water vapor flow, is presented. The device has been used for head-space sampling of benzene, toluene, ethylbenzene, and xylenes (BTEX) from water samples and compared with solid-phase microextraction. Under the same sampling conditions the analytical characteristics of the device for the BTEX compounds are better than those of solid-phase microextraction. Limits of detection and quantification are below 0.5 {mu} g L{sup -1}. (orig.)

  20. Pilot plant study on the extractive distillation of toluene-methylcyclohexane mixtures using NMP and the ionic liquid [hmim][TCB] as solvents

    NARCIS (Netherlands)

    Quijada-Maldonado, Esteban; Meindersma, G. Wytze; de Haan, A.B.

    2016-01-01

    The separation of the close-boiling point mixture: toluene - methylcyclohexane can be carried out by extractive distillation using the ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate ([hmim][TCB]), reported as promising solvent for the separation of this mixture. However, the polar

  1. "De Novo"-synthesis of chlorinated biphenyls, dibenzofurans and dibenzo-p-dioxins in the fly ash catalyzed reaction of toluene with hydrochloric acid

    NARCIS (Netherlands)

    Leer, E.W.B. de; Lexmond, R.J.; Zeeuw, M.A. de

    1989-01-01

    Toluene is converted into benzaldehyde and halogenated aromatic oxidation products in an air atmosphere at 425 °C with fly ash from a municipal waste incineration plant as the catalyst. Several halogenated products such as chlorinated and brominated benzenes, biphenyls and traces of PCDDs/PCDFs

  2. Effect of pH and loading manner on the start-up period of peat biofilter degrading xylene and toluene mixture

    Czech Academy of Sciences Publication Activity Database

    Marek, J.; Páca, J.; Halecký, M.; Koutský, B.; Sobotka, Miroslav; Keshavarz, T.

    2001-01-01

    Roč. 46, č. 3 (2001), s. 205-209 ISSN 0015-5632 R&D Projects: GA ČR GA104/99/1623 Institutional research plan: CEZ:AV0Z5020903 Keywords : biofilter * xylene * toluene Subject RIV: EE - Microbiology, Virology Impact factor: 0.776, year: 2001

  3. Purification, crystallization and preliminary X-ray diffraction studies of the three components of the toluene 2,3-dioxygenase enzyme system

    International Nuclear Information System (INIS)

    Lee, Kyoung; Friemann, Rosmarie; Parales, Juan V.; Gibson, David T.; Ramaswamy, S.

    2005-01-01

    All three components of the toluene dioxygenase system have been expressed, purified and crystallized. Pseudomonas putida F1 can grow with toluene as its sole source of carbon and energy. The initial reaction of the degradation of toluene is catalyzed by a three-component toluene dioxygenase enzyme system consisting of a reductase (Reductase TOL ), a ferredoxin (Ferredoxin TOL ) and a Rieske non-heme iron dioxygenase (Oxygenase TOL ). The three components and the apoenzyme of the dioxygenase (apo-Oxygenase TOL ) were overexpressed, purified and crystallized. Reductase TOL diffracts to 1.8 Å and belongs to space group P4 1 2 1 2, with unit-cell parameters a = b = 77.1, c = 156.3 Å. Ferredoxin TOL diffracts to 1.2 Å and belongs to space group P2 1 , with unit-cell parameters a = 30.5, b = 52.0, c = 30.95 Å, β = 113.7°. Apo-Oxygenase TOL and Oxygenase TOL diffract to 3.2 Å and belong to space group P4 3 32, with unit-cell parameters a = 235.9 Å and a = 234.5 Å, respectively

  4. H-Abstraction reactions by OH, HO2, O, O2 and benzyl radical addition to O2 and their implications for kinetic modelling of toluene oxidation.

    Science.gov (United States)

    Pelucchi, M; Cavallotti, C; Faravelli, T; Klippenstein, S J

    2018-02-01

    Alkylated aromatics constitute a significant fraction of the components commonly found in commercial fuels. Toluene is typically considered as a reference fuel. Together with n-heptane and iso-octane, it allows for realistic emulations of the behavior of real fuels by the means of surrogate mixture formulations. Moreover, it is a key precursor for the formation of poly-aromatic hydrocarbons, which are of relevance to understanding soot growth and oxidation mechanisms. In this study the POLIMI kinetic model is first updated based on the literature and on recent kinetic modelling studies of toluene pyrolysis and oxidation. Then, important reaction pathways are investigated by means of high-level theoretical methods, thereby advancing the present knowledge on toluene oxidation. H-Abstraction reactions by OH, HO 2 , O and O 2 , and the reactivity on the multi well benzyl-oxygen (C 6 H 5 CH 2 + O 2 ) potential energy surface (PES) were investigated using electronic structure calculations, transition state theory in its conventional, variational, and variable reaction coordinate forms (VRC-TST), and master equation calculations. Exploration of the effect on POLIMI model performance of literature rate constants and of the present calculations provides valuable guidelines for implementation of the new rate parameters in existing toluene kinetic models.

  5. Catalytic Steam Reforming of Toluene as a Model Compound of Biomass Gasification Tar Using Ni-CeO2/SBA-15 Catalysts

    Directory of Open Access Journals (Sweden)

    Erik Dahlquist

    2013-07-01

    Full Text Available Nickel supported on SBA-15 doped with CeO2 catalysts (Ni-CeO2/SBA-15 was prepared, and used for steam reforming of toluene which was selected as a model compound of biomass gasification tar. A fixed-bed lab-scale set was designed and employed to evaluate the catalytic performances of the Ni-CeO2/SBA-15 catalysts. Experiments were performed to reveal the effects of several factors on the toluene conversion and product gas composition, including the reaction temperature, steam/carbon (S/C ratio, and CeO2 loading content. Moreover, the catalysts were subjected to analysis of their carbon contents after the steam reforming experiments, as well as to test the catalytic stability over a long experimental period. The results indicated that the Ni-CeO2/SBA-15 catalysts exhibited promising capabilities on the toluene conversion, anti-coke deposition and catalytic stability. The toluene conversion reached as high as 98.9% at steam reforming temperature of 850 °C and S/C ratio of 3 using the Ni-CeO2(3wt%/SBA-15 catalyst. Negligible coke formation was detected on the used catalyst. The gaseous products mainly consisted of H2 and CO, together with a little CO2 and CH4.

  6. A kinetic mechanism for predicting secondary organic aerosol formation from toluene oxidation in the presence of NO x and natural sunlight

    Science.gov (United States)

    Hu, Di; Tolocka, Michael; Li, Qianfeng; Kamens, Richard M.

    A kinetic mechanism to predict secondary organic aerosol (SOA) formation from the photo-oxidation of toluene was developed. Aerosol phase chemistry that includes nucleation, gas-particle partitioning and particle-phase reactions as well as the gas-phase chemistry of toluene and its degradation products were represented. The mechanism was evaluated against experimental data obtained from the University of North Carolina (UNC) 270 m 3 dual outdoor aerosol smog chamber facility. The model adequately simulates the decay of toluene, the nitric oxide (NO) to nitrogen dioxide (NO 2) conversion and ozone formation. It also provides a reasonable prediction of SOA production under different conditions that range from 15 to 300 μg m -3. Speciation of simulated aerosol material shows that up to 70% of the aerosol mass comes from oligomers and polymers depending on initial reactant concentrations. The dominant particle-phase species predicted by the mechanism are glyoxal oligomers, ketene oligomers from the photolysis of the toluene OH reaction product 2-methyl-2,4-hexadienedial, organic nitrates, methyl nitro-phenol analogues, C7 organic peroxides, acylperoxy nitrates and for the low-concentration experiments, unsaturated hydroxy nitro acids.

  7. Regioselective double Kyodai nitration of toluene and chlorobenzene over zeolites. high preference for the 2,4-dinitro isomer at the second nitration stage.

    Science.gov (United States)

    Peng, X; Suzuki, H

    2001-11-01

    [reaction: see text]. The Kyodai nitration of toluene and chlorobenzene has been examined in the presence of a solid inorganic catalyst (montmorillonite K10, zeolite HZSM-5, or HBEA-25). Regioselection was quite low at the mononitration stage, but a considerably high preference for the 2,4-isomer was observed at the dinitration stage.

  8. IMPACT OF AEROSOL LIQUID WATER ON SECONDARY ORGANIC AEROSOL YIELDS OF IRRADIATED TOLUENE/PROPYLENE/NOX/(NH4)2SO4/AIR MIXUTRES

    Science.gov (United States)

    Laboratory experiments were conducted to assess whether the presence of liquid water on pre-existing submicron ammonium sulfate aerosols affects yields of condensible organic compounds. Toluene/propylene/NOX/air mixtures were irradiated in the presence of submicron ammonium su...

  9. Molecular level insights to the interaction of toluene with ZrO2-based biomass gasification gas clean-up catalysts

    NARCIS (Netherlands)

    Viinikainen, T.; Kauppi, I.; Korhonen, S.; Lefferts, Leonardus; Kanervo, J.; Lehtonen, J.

    2013-01-01

    Gasification of biomass, followed by ZrO2-catalyzed hot gas clean-up at 600–900 °C for the oxidation of impurities (such as tar), is an environmentally attractive way to produce heat and power or synthesis gas. The interaction of toluene (as a model compound for tar) with ZrO2-based gasification gas

  10. Subtoxic and toxic concentrations of benzene and toluene induce Nrf2-mediated antioxidative stress response and affect the central carbon metabolism in lung epithelial cells A549.

    Science.gov (United States)

    Murugesan, Kalaimathi; Baumann, Sven; Wissenbach, Dirk K; Kliemt, Stefanie; Kalkhof, Stefan; Otto, Wolfgang; Mögel, Iljana; Kohajda, Tibor; von Bergen, Martin; Tomm, Janina M

    2013-11-01

    Since people in industrialized countries spend most of their time indoors, the effects of indoor contaminants such as volatile organic compounds become more and more relevant. Benzene and toluene are among the most abundant compounds in the highly heterogeneous group of indoor volatile organic compounds. In order to understand their effects on lung epithelial cells (A549) representing lung's first line of defense, we chose a global proteome and a targeted metabolome approach in order to detect adverse outcome pathways caused by exposure to benzene and toluene. Using a DIGE approach, 93 of 469 detected protein spots were found to be differentially expressed after exposure to benzene, and 79 of these spots were identified by MS. Pathway analysis revealed an enrichment of proteins involved in Nrf2-mediated and oxidative stress response glycolysis/gluconeogenesis. The occurrence of oxidative stress at nonacute toxic concentrations of benzene and toluene was confirmed by the upregulation of the stress related proteins NQO1 and SOD1. The changes in metabolism were validated by ion chromatography MS/MS analysis revealing significant changes of glucose-6-phosphate, fructose-6-phosphate, 3-phosphoglycerate, and NADPH. The molecular alterations identified as a result of benzene and toluene exposure demonstrate the detrimental effect of nonacute toxic concentrations on lung epithelial cells. The data provided here will allow for a targeted validation in in vivo models. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-15

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

  12. Assessment of filtration efficiency and physiological responses of selected plant species to indoor air pollutants (toluene and 2-ethylhexanol) under chamber conditions.

    Science.gov (United States)

    Hörmann, Vanessa; Brenske, Klaus-Reinhard; Ulrichs, Christian

    2018-01-01

    Three common plant species (Dieffenbachia maculata, Spathiphyllum wallisii, and Asparagus densiflorus) were tested against their capacity to remove the air pollutants toluene (20.0 mg m -3 ) and 2-ethylhexanol (14.6 mg m -3 ) under light or under dark in chamber experiments of 48-h duration. Results revealed only limited pollutant filtration capabilities and indicate that aerial plant parts of the tested species are only of limited value for indoor air quality improvement. The removal rate constant ranged for toluene from 3.4 to 5.7 L h -1  m -2 leaf area with no significant differences between plant species or light conditions (light/dark). The values for 2-ethylhexanol were somewhat lower, fluctuating around 2 L h -1  m -2 leaf area for all plant species tested, whereas differences between light and dark were observed for two of the three species. In addition to pollutant removal, CO 2 fixation/respiration and transpiration as well as quantum yield were evaluated. These physiological characteristics seem to have no major impact on the VOC removal rate constant. Exposure to toluene or 2-ethylhexanol revealed no or only minor effects on D. maculata and S. wallisii. In contrast, a decrease in quantum yield and CO 2 fixation was observed for A. densiflorus when exposed to 2-ethylhexanol or toluene under light, indicating phytotoxic effects in this species.

  13. The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

    Directory of Open Access Journals (Sweden)

    H. Suwarno

    2009-07-01

    Full Text Available The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.

  14. On-line CO, CO2 emissions evaluation and (benzene, toluene, xylene) determination from experimental burn of tropical biomass.

    Science.gov (United States)

    Tawfiq, Mohammed F; Aroua, Mohamed Kheireddine; Sulaiman, Nik Meriam Nik

    2015-07-01

    Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass. Copyright © 2015. Published by Elsevier B.V.

  15. Comparison of solvent/derivatization agent systems for determination of extractable toluene diisocyanate from flexible polyurethane foam.

    Science.gov (United States)

    Vangronsveld, Erik; Berckmans, Steven; Spence, Mark

    2013-06-01

    Flexible polyurethane foam (FPF) is produced from the reaction of toluene diisocyanate (TDI) and polyols. Limited and conflicting results exist in the literature concerning the presence of unreacted TDI remaining in FPF as determined by various solvent extraction and analysis techniques. This study reports investigations into the effect of several solvent/derivatization agent combinations on extractable TDI results and suggests a preferred method. The suggested preferred method employs a syringe-based multiple extraction of foam samples with a toluene solution of 1-(2-methoxyphenyl)-piperazine. Extracts are analyzed by liquid chromatography using an ion trap mass spectrometry detection technique. Detection limits of the method are ~10ng TDI g(-1) foam (10 ppb, w/w) for each TDI isomer (i.e. 2,4-TDI and 2,6-TDI). The method was evaluated by a three-laboratory interlaboratory comparison using two representative foam samples. The total extractable TDI results found by the three labs for the two foams were in good agreement (relative standard deviation of the mean of 30-40%). The method has utility as a basis for comparing FPFs, but the interpretation of extractable TDI results using any solvent as the true value for 'free' or 'unreacted' TDI in the foam is problematic, as demonstrated by the difference in the extracted TDI results from the different extraction systems studied. Further, a consideration of polyurethane foam chemistry raises the possibility that extractable TDI may result from decomposition of parts of the foam structure (e.g. dimers, biurets, and allophanates) by the extraction system.

  16. Use of selective ionic liquids and ionic liquid/salt mixtures as entrainer in a (vapor + liquid) system to separate n-heptane from toluene

    International Nuclear Information System (INIS)

    González, Emilio J.; Navarro, Pablo; Larriba, Marcos; García, Julián; Rodríguez, Francisco

    2015-01-01

    Highlights: • Two thiocyanate-based ionic liquids were tested as entrainers to separate n-heptane and toluene. • (Vapor + liquid) equilibrium data were measured at T = (323.2, 343.2, and 363.2) K. • Relative volatility of n-heptane from toluene using ionic liquids was calculated. • VLE data for {n-heptane + toluene + ionic liquid} mixtures were model using NRTL. • Mixtures of [EMim][SCN]/inorganic salts were also tested as entrainers. - Abstract: During the last years, a large number of studies have evaluated the ability of ionic liquids (ILs) to separate aromatic from aliphatic hydrocarbons by liquid extraction. Nevertheless, in order to design a global process, a post-extraction step based on the aromatic recovery from the extract stream and the regeneration of the IL is required. Taking into account the negligible vapor pressure of the ILs, the use of separation units based on the difference of volatility among the components of the extract could be an appropriate way. However, that requires additional (vapor + liquid) equilibrium (VLE) data, which are scarce today. In this work, the isothermal VLE data for {n-heptane + toluene + 1-ethyl-3-methylimidazolium thiocyanate ([EMim][SCN])} and {n-heptane + toluene + 1-butyl-3-methylimidazolium thiocyanate ([BMim][SCN])} mixtures were experimentally measured at T = (323.2, 343.2 and 363.2) K over the whole composition range within the rich-IL miscibility region. For that, a static headspace gas chromatograph (HS-GC) was used. In addition, the non-random two liquids (NRTL) thermodynamic model was satisfactory applied to correlate the experimental VLE data. Finally, the effect of thiocyanate-based inorganic salts (AgSCN, Co(SCN) 2 and CuSCN) on the phase behavior of the above mentioned mixtures were also analyzed through the experimental determination of the isothermal VLE of the pseudo-ternary systems {n-heptane + toluene + [EMim][SCN]/salt mixture}. The obtained results show that the use of pure thiocyanate

  17. The role of substrate binding pocket residues phenylalanine 176 and phenylalanine 196 on Pseudomonas sp. OX1 toluene o-xylene monooxygenase activity and regiospecificity.

    Science.gov (United States)

    Sönmez, Burcu; Yanık-Yıldırım, K Cansu; Wood, Thomas K; Vardar-Schara, Gönül

    2014-08-01

    Saturation mutagenesis was used to generate eleven substitutions of toluene-o-xylene monooxygenase (ToMO) at alpha subunit (TouA) positions F176 and F196 among which nine were novel: F176H, F176N, F176S, F176T, F196A, F196L, F196T, F196Y, F196H, F196I, and F196V. By testing the substrates phenol, toluene, and naphthalene, these positions were found to influence ToMO oxidation activity and regiospecificity. Specifically, TouA variant F176H was identified that had 4.7-, 4.3-, and 1.8-fold faster hydroxylation activity towards phenol, toluene, and naphthalene, respectively, compared to native ToMO. The F176H variant also produced the novel product hydroquinone (61%) from phenol, made twofold more 2-naphthol from naphthalene (34% vs. 16% by the wild-type ToMO), and had the regiospecificity of toluene changed from 51% to 73% p-cresol. The TouA F176N variant had the most para-hydroxylation capability, forming p-cresol (92%) from toluene and hydroquinone (82%) from phenol as the major product, whereas native ToMO formed 30% o-cresol, 19% m-cresol, and 51% of p-cresol from toluene and 100% catechol from phenol. For naphthalene oxidation, TouA variant F176S exhibited the largest shift in the product distribution by producing threefold more 2-naphthol. Among the other F196 variants, F196L produced catechol from phenol two times faster than the wild-type enzyme. The TouA F196I variant produced twofold less o-cresol and 19% more p-cresol from toluene, and the TouA F196A variant produced 62% more 2-naphthol from naphthalene compared to wild-type ToMO. Both of these positions have never been studied through the saturation mutagenesis and some of the best substitutions uncovered here have never been predicted and characterized for aromatics hydroxylation. © 2014 Wiley Periodicals, Inc.

  18. Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

    Science.gov (United States)

    Landmeyer, James E.; Effinger, Thomas N.

    2016-01-01

    Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

  19. Management of Menopausal Symptoms

    Science.gov (United States)

    Kaunitz, Andrew M.; Manson, JoAnn E.

    2015-01-01

    Most menopausal women experience vasomotor symptoms, with bothersome symptoms often lasting longer than one decade. Hormone therapy (HT) represents the most effective treatment for these symptoms, with oral and transdermal estrogen formulations having comparable efficacy. Findings from the Women’s Health Initiative and other recent randomized clinical trials have helped to clarify the benefits and risks of combination estrogen-progestin and estrogen-alone therapy. Absolute risks observed with HT tended to be small, especially in younger women. Neither regimen affected all-cause mortality rates. Given the lower rates of adverse events on HT among women close to menopause onset and at lower baseline risk of cardiovascular disease, risk stratification and personalized risk assessment appears to represent a sound strategy for optimizing the benefit: risk profile and safety of hormone therapy. Systemic HT should not be arbitrarily stopped at age 65; instead treatment duration should be individualized based on patients’ risk profiles and personal preferences. Genitourinary syndrome of menopause represents a common condition that adversely impacts the quality of life of many menopausal women. Without treatment, symptoms worsen over time. Low-dose vaginal estrogen represents highly effective treatment for this condition. Because custom-compounded hormones have not been tested for efficacy or safety, U.S. Food and Drug Administration (FDA)-approved HT is preferred. A low dose formulation of paroxetine mesylate currently represents the only nonhormonal medication FDA-approved to treat vasomotor symptoms. Gynecologists and other clinicians who remain abreast of data addressing the benefit: risk profile of hormonal and nonhormonal treatments can help menopausal women make sound choices regarding management of menopausal symptoms. PMID:26348174

  20. Management of Menopausal Symptoms.

    Science.gov (United States)

    Kaunitz, Andrew M; Manson, JoAnn E

    2015-10-01

    Most menopausal women experience vasomotor symptoms with bothersome symptoms often lasting longer than one decade. Hormone therapy (HT) represents the most effective treatment for these symptoms with oral and transdermal estrogen formulations having comparable efficacy. Findings from the Women's Health Initiative and other recent randomized clinical trials have helped to clarify the benefits and risks of combination estrogen-progestin and estrogen-alone therapy. Absolute risks observed with HT tended to be small, especially in younger women. Neither regimen increased all-cause mortality rates. Given the lower rates of adverse events on HT among women close to menopause onset and at lower baseline risk of cardiovascular disease, risk stratification and personalized risk assessment appear to represent a sound strategy for optimizing the benefit-risk profile and safety of HT. Systemic HT should not be arbitrarily stopped at age 65 years; instead treatment duration should be individualized based on patients' risk profiles and personal preferences. Genitourinary syndrome of menopause represents a common condition that adversely affects the quality of life of many menopausal women. Without treatment, symptoms worsen over time. Low-dose vaginal estrogen represents highly effective treatment for this condition. Because custom-compounded hormones have not been tested for efficacy or safety, U.S. Food and Drug Administration (FDA)-approved HT is preferred. A low-dose formulation of paroxetine mesylate currently represents the only nonhormonal medication FDA-approved to treat vasomotor symptoms. Gynecologists and other clinicians who remain abreast of data addressing the benefit-risk profile of hormonal and nonhormonal treatments can help menopausal women make sound choices regarding management of menopausal symptoms.

  1. Social Sensations of Symptoms:

    DEFF Research Database (Denmark)

    Meinert, Lotte; Whyte, Susan Reynolds

    2017-01-01

    The interpretation of sensations and the recognition of symptoms of a sickness, as well as the movement to seek treatment, have long been recognized in medical anthropology as inherently social processes. Based on cases of HIV and trauma (PTSD) in Uganda, we show that even the first signs...... and sensations of sickness can be radically social. The sensing body can be a ‘social body’ – a family, a couple, a network – a unit that transcends the individual body. In this article we focus on four aspects of the sociality of sensations and symptoms: mode of transmission; the shared experience of sensations...

  2. Association between ADHD symptoms and anxiety symptoms in Taiwanese adolescents.

    Science.gov (United States)

    Liu, Tai-Ling; Yang, Pinchen; Ko, Chih-Hung; Yen, Ju-Yu; Yen, Cheng-Fang

    2014-07-01

    The aims of this cross-sectional study were to examine the association between significant ADHD symptoms and the four domains of anxiety symptoms on the Taiwanese version of Multidimensional Anxiety Scale for Children (MASC-T) and to examine the moderating effects of sociodemographic characteristics on this association among Taiwanese adolescents in the community. A total of 4,716 adolescents in Grades 7 through 12 in southern Taiwan completed the MASC-T, the ADHD Self-Rated Scale, the Mandarin Chinese version of the Center for Epidemiological Studies Depression Scale, the Rosenberg Self-Esteem Scale, and a questionnaire about sociodemographic characteristics. Multiple regression analysis was used to examine both the association of significant ADHD symptoms with four domains of anxiety symptoms on the MASC-T and the moderating effects of sociodemographic characteristics on this association. The adolescents with significant ADHD symptoms had more severe total anxiety symptoms, physical symptoms, social anxiety symptoms, and separation/panic symptoms for three domains of the MASC-T but less harm avoidance than did those without significant ADHD symptoms. Age, gender, and low self-esteem had moderating effects on the association between significant ADHD symptoms and anxiety symptoms for some domains of the MASC-T. The results of this study suggest a significant association between significant ADHD symptoms and the severity of anxiety symptoms in adolescents. Clinicians must evaluate anxiety symptoms among adolescents with ADHD and arrange comprehensive treatment programs. © 2012 SAGE Publications.

  3. Emotional symptoms among adolescents

    DEFF Research Database (Denmark)

    Meilstrup, Charlotte; Ersbøll, Annette K; Nielsen, Line

    2015-01-01

    BACKGROUND: Large proportions of schoolchildren suffer from emotional symptoms and there are large variations across schools. It is unknown to what degree this variation is due to composition of schoolchildren in each school or to contextual factors. Objectives are to identify factors at individu...

  4. 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)

  5. Effect of Key Parameters on the Photocatalytic Oxidation of Toluene at Low Concentrations in Air under 254 + 185 nm UV Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Quici, Natalia; Vera, Maria L.; Choi, Hyeok; Puma, Gianluca Li; Dionysiou, Dionysios D.; Litter, Marta I.; Destaillats, Hugo

    2009-07-01

    The effect of key experimental parameters on the removal of toluene under 254 + 185 nm irradiation was investigated using a benchtop photocatalytic flow reactor. Toluenewas introduced at low concentrations between 10 and 500 ppbv, typical of indoorenvironments, and reacted on TiO2-coated Raschig rings. Two different TiO2-coated rings were prepared: in one case, by dip-coating using a P25 aqueous suspension and, on the other, using an organic/inorganic sol-gel method that produced thin films of mesoporous anatase. Flow rates in the photoreactor varied between 4 L min-1 and 125 mL min-1, leading to residence times in the range 100 ms< tau< 2 s. For these conditions, toluene removal efficiencies were between 30 and 90percent, indicating that the system did not achieve total conversion in any case. For each air flow rate, the conversion oftoluene was significantly higher when the reactor length was 10 cm, as compared with 5 cm; however, only marginal increases in conversions were achieved in the two reactor lengths at equal residence time and different concentration of toluene, suggesting that that the reactor is effectively behaving as an ideal reactor and that the reaction is first-order in the concentration of toluene. Experiments were carried out between 0 and 66percent relative humidity (RH), the fastest reaction rate being observed at moderately low humidity conditions (10percent RH), with respect to both dry air and higher humidity levels. Formaldehyde was formed as a partial oxidation byproduct at low and at high residence times (240 and 960 ms), although higher formaldehyde molar yields (up to 20percent) were observed at low tau (240 ms) and moderate humidity conditions (10 and 33percent), suggesting that both tau and RH can be optimized toreduce the formation of harmful intermediates. Toluene removal efficiency increased with the TiO2 thickness (i.e., mass) until a maximum value of 500 nm, beyond which the removal efficiency decreased. This should be

  6. Unthinkability and psychosomatic symptoms.

    Science.gov (United States)

    Neri, C

    W. R. Bion (1952) has pointed out a connection between alterations in the development of the "apparatus for thinking thoughts" and psychosomatic symptoms. Many authors have used this insight, from their own points of view, as a basis for describing this deficiency in thought and in the capacity to formulate images related to the development of psychosomatic symptoms (Krystal & McDougall 1979; Segal, 1950, 1958). This paper applies this hypothesis to a clinical case in which special emphasis is given to the symbolic deficiency, its effect on transference-countertransference, and its relation to falsification, "hyposymbolization," and to a specific phenomenon that could be called "hypersymbolization," in which many meanings are embodied in the same symbol.

  7. Hearing symptoms personal stereos.

    Science.gov (United States)

    da Luz, Tiara Santos; Borja, Ana Lúcia Vieira de Freitas

    2012-04-01

     Practical and portable the personal stereos if had become almost indispensable accessories in the day the day. Studies disclose that the portable players of music can cause auditory damages in the long run for who hear music in high volume for a drawn out time.  to verify the prevalence of auditory symptoms in users of amplified players and to know its habits of use  Observational prospective study of transversal cut carried through in three institutions of education of the city of Salvador BA, being two of public net and one of the private net. 400 students had answered to the questionnaire, of both the sex, between 14 and 30 years that had related the habit to use personal stereos.  The symptoms most prevalent had been hyperacusis (43.5%), auricular fullness (30.5%) and humming (27.5), being that the humming is the symptom most present in the population youngest. How much to the daily habits: 62.3% frequent use, 57% in raised intensities, 34% in drawn out periods. An inverse relation between exposition time was verified and the band of age (p = 0,000) and direct with the prevalence of the humming.  Although to admit to have knowledge on the damages that the exposition the sound of high intensity can cause the hearing, the daily habits of the young evidence the inadequate use of the portable stereos characterized by long periods of exposition, raised intensities, frequent use and preference for the insertion phones. The high prevalence of symptoms after the use suggests a bigger risk for the hearing of these young.

  8. Hearing symptoms personal stereos

    Directory of Open Access Journals (Sweden)

    Tiara Santos da Luz1

    2012-01-01

    Full Text Available Introduction: Practical and portable the personal stereos if had become almost indispensable accessories in the day the day. Studies disclose that the portable players of music can cause auditory damages in the long run for who hear music in high volume for a drawn out time. Objective: to verify the prevalence of auditory symptoms in users of amplified players and to know its habits of use. Method: Observational prospective study of transversal cut carried through in three institutions of education of the city of Salvador BA, being two of public net and one of the private net. 400 students had answered to the questionnaire, of both the sex, between 14 and 30 years that had related the habit to use personal stereos. Results: The symptoms most prevalent had been hyperacusis (43.5%, auricular fullness (30.5% and humming (27.5, being that the humming is the symptom most present in the population youngest. How much to the daily habits: 62.3% frequent use, 57% in raised intensities, 34% in drawn out periods. An inverse relation between exposition time was verified and the band of age (p=0,000 and direct with the prevalence of the humming. Conclusion: Although to admit to have knowledge on the damages that the exposition the sound of high intensity can cause the hearing, the daily habits of the young evidence the inadequate use of the portable stereos characterized by long periods of exposition, raised intensities, frequent use and preference for the insertion phones. The high prevalence of symptoms after the use suggests a bigger risk for the hearing of these young.

  9. Respiratory symptoms of megaesophagus

    Directory of Open Access Journals (Sweden)

    Fabio Di Stefano

    2013-03-01

    Full Text Available Megaesophagus as the end result of achalasia is the consequence of disordered peristalsis and the slow decompensation of the esophageal muscular layer. The main symptoms of achalasia are dysphagia, regurgitation, chest pain and weight loss, but respiratory symptoms, such as coughing, particularly when patients lie in a horizontal position, may also be common due to microaspiration. A 70-year old woman suffered from a nocturnal cough and shortness of breath with stridor. She reported difficulty in swallowing food over the past ten years, but had adapted by eating a semi-liquid diet. Chest X-ray showed right hemithorax patchy opacities projecting from the posterior mediastinum. Chest computed tomography scan showed a marked dilatation of the esophagus with abundant food residues. Endoscopy confirmed the diagnosis of megaesophagus due to esophageal achalasia, excluding other causes of obstruction, such as secondary esophagitis, polyps, leiomyoma or leiomyosarcoma. In the elderly population, swallowing difficulties due to esophageal achalasia are often underestimated and less troublesome than the respiratory symptoms that are caused by microaspiration. The diagnosis of esophageal achalasia, although uncommon, should be considered in patients with nocturnal chronic coughs and shortness of breath with stridor when concomitant swallowing difficulties are present.

  10. Neurobiology Underlying Fibromyalgia Symptoms

    Directory of Open Access Journals (Sweden)

    Marta Ceko

    2012-01-01

    Full Text Available Fibromyalgia is characterized by chronic widespread pain, clinical symptoms that include cognitive and sleep disturbances, and other abnormalities such as increased sensitivity to painful stimuli, increased sensitivity to multiple sensory modalities, and altered pain modulatory mechanisms. Here we relate experimental findings of fibromyalgia symptoms to anatomical and functional brain changes. Neuroimaging studies show augmented sensory processing in pain-related areas, which, together with gray matter decreases and neurochemical abnormalities in areas related to pain modulation, supports the psychophysical evidence of altered pain perception and inhibition. Gray matter decreases in areas related to emotional decision making and working memory suggest that cognitive disturbances could be related to brain alterations. Altered levels of neurotransmitters involved in sleep regulation link disordered sleep to neurochemical abnormalities. Thus, current evidence supports the view that at least some fibromyalgia symptoms are associated with brain dysfunctions or alterations, giving the long-held “it is all in your head” view of the disorder a new meaning.

  11. ADHD Symptoms and Subtypes: Relationship between Childhood and Adolescent Symptoms

    Science.gov (United States)

    Hurtig, Tuula; Ebeling, Hanna; Taanila, Anja; Miettunen, Jouko; Smalley, Susan L.; McGough, James J.; Loo, Sandra K.; Jarvelin, Marjo-Riitta; Moilanen, Irma K.

    2007-01-01

    A study aims to examine attention-deficit/hyperactivity disorder(ADHD) symptoms and subtypes in childhood and adolescence. The results conclude the persistence of ADHD from childhood to adolescence with specific symptoms contributing to persistent ADHD.

  12. Irradiation with benzene, toluene and phenol electron beams in aqueous solution; Irradiacion con haces de electrones de benceno, tolueno y fenol en solucion acuosa

    Energy Technology Data Exchange (ETDEWEB)

    Santoyo O, E.L.; Lopez V, H.; Vazquez A, O.; Lizama S, B.E.; Garcia F, M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1998-07-01

    It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO{sub 2} and H{sub 2}O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author.

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

    Science.gov (United States)

    Lee, Eun-Hee; Cho, Kyung-Suk

    2009-08-15

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

  14. The temperature influence in the toluene diffusion coefficient in type y zeolites; Influencia da temperatura no coeficiente de difusao do tolueno em zeolitas do tipo Y

    Energy Technology Data Exchange (ETDEWEB)

    Schwanke, R.O.; Chagas, C.U.; Souza, S.M.A. Guelli U.; Souza, A.A. Ulson de [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Quimica e Engenharia de Alimentos]. E-mail: augusto@enq.ufsc.br; Oliveira, J.S. [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Quimica]. E-mail: juarzoli@engquim.ufpr.br; Maliska, C.R. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica]. E-mail: maliska@sinmec.ufsc.br

    2003-07-01

    This study presents the results of the toluene intra crystalline diffusivity in pellets of Y-type zeolite, packed in a fixed bed column. For the evaluation of the adsorption dynamics, High Performance Liquid Chromatography (HPLC) technique was utilized, which promotes the adsorption of liquids in extremely small and uniforms particles to generate a high sensibility. The equilibrium and kinetics adsorption parameters were obtained through the pulse chromatography technique and evaluated by the method of moments, based on the analysis of the first and second statistical moments of the chromatographic response peaks. The experiment was performed with changes in the diffusional properties of the eluent/sorbate/adsorbent system, such as feeding flow and temperature. The equilibrium constant, the adsorption energy and the temperature influence over toluene diffusivity were determined. (author)

  15. (Liquid + liquid) equilibria of (heptane, or hexane, or cyclohexane + toluene + 1,3-dimethyl-2-imidazolidinone) ternary systems at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Bilgin, Mehmet, E-mail: mbilgin@istanbul.edu.t [Istanbul University, Engineering Faculty, Chemical Engineering Department, 34320 Avcilar, Istanbul (Turkey)

    2010-04-15

    Experimental (liquid + liquid) equilibrium data for the mixtures of (heptane, or hexane, or cyclohexane + toluene + 1,3-dimethyl-2-imidazolidinone) were determined at T = 298.15 K and P = 101.3 kPa. The solubility (binodal) curves and tie-line end compositions are reported for the related mixtures and presented as complete phase diagrams. Distribution coefficients and separation factors were evaluated for the immiscibility region. The reliability of the experimental tie-line results was verified by using the Othmer-Tobias correlation. The experimental tie-line data were correlated by UNIQUAC model, which gave satisfactory representation for the systems. It was observed that the separation of toluene from cyclohexane is easier to achieve than from heptane and hexane.

  16. Flotation-spectrophotometric determination of ruthenium in the Ru(IV)-chloride-rhodamine 6G-toluene system

    International Nuclear Information System (INIS)

    Balcerzak, M.

    1985-01-01

    The reduction of RuO 4 in hydrochloric acid has been examined. A sensitive flotation-spectrophotometric method of the determination of ruthenium based on the ion associate formed by the anionic chlorid complex of ruthenium RuCl 2- 6 with the basic dye Rhodamine 6G (R6G) has been developed. The solution of the ion associate obeys Beer's law up to the concentration of 0.25 μg Ru/ml. The ion associate precipitates when the aqueous solution is shaken with toluene. The separated compound is dissolved in acetone. The molar absorptivity (epsilon) at 530 nm is 5.1 x 10 5 l x mole -1 x cm -1 . The relative standard deviation is 3-7%. The mole ratio of Ru:R6G in the complex is 1:5. Osmium reacts similarly. The determination of ruthenium can be selective after the preliminary separation of osmium as OsO 4 . The method was applied to the determination of microgram amounts of ruthenium in crucible platinum. (Author)

  17. Elucidating the fate of a mixed toluene, DHM, methanol, and i-propanol plume during in situ bioremediation

    Science.gov (United States)

    Verardo, E.; Atteia, O.; Prommer, H.

    2017-06-01

    Organic pollutants such as solvents or petroleum products are widespread contaminants in soil and groundwater systems. In-situ bioremediation is a commonly used remediation technology to clean up the subsurface to eliminate the risks of toxic substances to reach potential receptors in surface waters or drinking water wells. This study discusses the development of a subsurface model to analyse the performance of an actively operating field-scale enhanced bioremediation scheme. The study site was affected by a mixed toluene, dihydromyrcenol (DHM), methanol, and i-propanol plume. A high-resolution, time-series of data was used to constrain the model development and calibration. The analysis shows that the observed failure of the treatment system is linked to an inefficient oxygen injection pattern. Moreover, the model simulations also suggest that additional contaminant spillages have occurred in 2012. Those additional spillages and their associated additional oxygen demand resulted in a significant increase in contaminant fluxes that remained untreated. The study emphasises the important role that reactive transport modelling can play in data analyses and for enhancing remediation efficiency.

  18. Numerical modeling of subsurface release and fate of benzene and toluene in coastal aquifers subjected to tides

    Science.gov (United States)

    Geng, Xiaolong; Boufadel, Michel C.; Cui, Fangda

    2017-08-01

    A numerical study was undertaken to investigate subsurface release and fate of benzene and toluene in a tidally influenced beach. The simulations were conducted by using a numerical model BIOMARUN, which coupled a multi-Monod kinetic model BIOB to a density-dependent variably saturated groundwater flow model MARUN. The fate and transport of the contaminant plume were characterized by computing its centroid trajectory, spreading area and percentage of biodegradation in beach saturated and unsaturated zone, respectively. Key factors likely affecting this process were investigated, including tide amplitude, capillarity and hydraulic conductivity. It was found that aerobic biodegradation was the major fate of the contaminant plume in the beach. Tidal action twisted the centroid of the contaminant plume during its migration in the beach, which increased the residence time of the plume in the beach. High tidal range significantly altered the spatial distribution of the contaminant biodegradation in the beach. In contrast, the capillary fringe had impacts on the percentage of benzene biodegraded in the saturated and unsaturated zone of the beach. The increase in capillary fringe enhanced the percentage of the contaminant biodegraded in the unsaturated zone, up to 40%, which is comparable to that in the saturated zone. Hydraulic conductivity seemed to have large impacts on the biodegradation rate of the contaminant in the beach. Higher hydraulic conductivity induced faster contaminant biodegradation in the beach.

  19. p-toluene sulfonic acid doped polyaniline carbon nanotube composites: synthesis via different routes and modified properties

    Directory of Open Access Journals (Sweden)

    ASHOK K. SHARMA

    2013-04-01

    Full Text Available Composites of polyaniline and carbon nanotube (CNT were prepared by in-situ chemical polymerization method using various aniline concentrations in the initial polymerization solution with p-toluene sulfonic acid (PTS as secondary dopant and mechanical mixing of the PANI and CNT using different weight ratios of PANI and CNTs. The structural characterizations of the composites were done by Fourier transform infrared (FTIR and Ultra violet visible spectroscopy (UV-Visible. Scanning electron microscopy (SEM was used to characterize the surface morphology of the composites. It was found that the composites prepared by in-situ chemical polymerization had smoother surface morphology in comparison to the composites obtained by mechanical mixing. The capacitive studies reveal that the in-situ composite has synergistic effect and the specific capacitance of the composite calculated from cyclic voltammogram (CV was 385.1 F/g. Thermal studies indicate that the composites are stable as compared to PANI alone showing that the CNT contributes towards thermal stability in the PANI-CNT composites.

  20. Determination of benzene, toluene, ethylbenzene and xylenes in air by solid phase micro-extraction/gas chromatography/mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tumbiolo, Simonetta; Gal, Jean-Francois; Maria, Pierre-Charles [Universite de Nice-Sophia Antipolis, Laboratoire de Radiochimie, Sciences Analytiques et Environnement, Faculte des Sciences, Nice Cedex 2 (France); Zerbinati, Orfeo [Universita del Piemonte Orientale ' ' Amedeo Avogadro' ' , Dipartimento di Scienze e Tecnologie Avanzate, Alessandria (Italy)

    2004-11-01

    The aim of the study was to analyse BTEX compounds (benzene, toluene, ethylbenzene, xylenes) in air by solid phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS), and this article presents the features of the calibration method proposed. Examples of real-world air analysis are given. Standard gaseous mixtures of BTEX in air were generated by dynamic dilution. SPME sampling was carried out under non-equilibrium conditions using a Carboxen/PDMS fibre exposed for 30 min to standard gas mixtures or to ambient air. The behaviour of the analytical response was studied from 0 to 65 {mu}g/m{sup 3} by adding increasing amounts of BTEX to the air matrix. Detection limits range from 0.05 to 0.1 {mu}g/m{sup 3} for benzene, depending on the fibre. Inter-fibre relative standard deviations (reproducibility) are larger than 18%, although the repeatability for an individual fibre is better than 10%. Therefore, each fibre should be considered to be a particular sampling device, and characterised individually depending on the required accuracy. Sampling indoor and outdoor air by SPME appears to be a suitable short-delay diagnostic method for volatile organic compounds, taking advantage of short sampling time and simplicity. (orig.)