WorldWideScience

Sample records for partial air oxidation

  1. Adiabatic Gasification and Pyrolysis of Coffee Husk Using Air-Steam for Partial Oxidation

    OpenAIRE

    Catalina Rodriguez; Gerardo Gordillo

    2011-01-01

    Colombian coffee industry produces about 0.6 million tons of husk (CH) per year which could serve as feedstock for thermal gasification to produce gaseous and liquid fuels. The current paper deals with: (i) CH adiabatic gasification modeling using air-steam blends for partial oxidation and (ii) experimental thermogravimetric analysis to determine the CH activation energy (E). The Chemical Equilibrium with Applications Program (CEA), developed by NASA, was used to estimate the effect of equiva...

  2. Adiabatic Gasification and Pyrolysis of Coffee Husk Using Air-Steam for Partial Oxidation

    Directory of Open Access Journals (Sweden)

    Catalina Rodriguez

    2011-01-01

    Full Text Available Colombian coffee industry produces about 0.6 million tons of husk (CH per year which could serve as feedstock for thermal gasification to produce gaseous and liquid fuels. The current paper deals with: (i CH adiabatic gasification modeling using air-steam blends for partial oxidation and (ii experimental thermogravimetric analysis to determine the CH activation energy (E. The Chemical Equilibrium with Applications Program (CEA, developed by NASA, was used to estimate the effect of equivalence ratio (ER and steam to fuel ratio (S : F on equilibrium temperature and gas composition of ~150 species. Also, an atom balance model was developed for comparison purposes. The results showed that increased ER and (S : F ratios produce mixtures that are rich in H2 and CO2 but poor in CO. The value for the activation energy was estimated to be 221 kJ/kmol.

  3. Adiabatic Fixed-Bed Gasification of Colombian Coffee Husk Using Air-Steam Blends for Partial Oxidation

    Directory of Open Access Journals (Sweden)

    Javier Bonilla

    2017-01-01

    Full Text Available The increasing energy consumption, mostly supplied by fossil fuels, has motivated the research and development of alternative fuel technologies to decrease the humanity’s dependence on fossil fuels, which leads to pollution of natural sources. Small-scale biomass gasification, using air-steam blends for partial oxidation, is a good alternative since biomass is a neutral carbon feedstock for sustainable energy generation. This research presents results obtained from an experimental study on coffee husk (CH gasification, using air-steam blends for partial oxidation in a 10 kW fixed-bed gasifier. Parametric studies on equivalence ratio (ER (1.53 < ER < 6.11 and steam-fuel (SF ratio (0.23 < SF < 0.89 were carried out. The results show that increasing both SF and ER results in a syngas rich in CH4 and H2 but poor in CO. Also, decreased SF and ER decrease the peak temperature (Tpeak at the gasifier combustion zone. The syngas high heating value (HHV ranged from 3112 kJ/SATPm3 to 5085 kJ/SATPm3 and its maximum value was obtained at SF = 0.87 and ER = 4.09. The dry basis molar concentrations of the species, produced under those operating conditions (1.53 < ER < 6.11 and 0.23 < SF < 0.89, were between 1.12 and 4.1% for CH4, between 7.77 and 13.49% for CO, and between 7.54 and 19.07% for H2. Other species were in trace amount.

  4. Partial oxidation process

    International Nuclear Information System (INIS)

    Najjar, M.S.

    1987-01-01

    A process is described for the production of gaseous mixtures comprising H/sub 2/+CO by the partial oxidation of a fuel feedstock comprising a heavy liquid hydrocarbonaceous fuel having a nickel, iron, and vanadium-containing ash or petroleum coke having a nickel, iron, and vanadium-containing ash, or mixtures thereof. The feedstock includes a minimum of 0.5 wt. % of sulfur and the ash includes a minimum of 5.0 wt. % vanadium, a minimum of 0.5 ppm nickel, and a minimum of 0.5 ppm iron. The process comprises: (1) mixing together a copper-containing additive with the fuel feedstock; wherein the weight ratio of copper-containing additive to ash in the fuel feedstock is in the range of about 1.0-10.0, and there is at least 10 parts by weight of copper for each part by weight of vanadium; (2) reacting the mixture from (1) at a temperature in the range of 2200 0 F to 2900 0 F and a pressure in the range of about 5 to 250 atmospheres in a free-flow refactory lined partial oxidation reaction zone with a free-oxygen containing gas in the presence of a temperature moderator and in a reducing atmosphere to produce a hot raw effluent gas stream comprising H/sub 2/+CO and entrained molten slag; and where in the reaction zone and the copper-containing additive combines with at least a portion of the nickel and iron constituents and sulfur found in the feedstock to produce a liquid phase washing agent that collects and transports at least a portion of the vanadium-containing oxide laths and spinels and other ash components and refractory out of the reaction zone; and (3) separating nongaseous materials from the hot raw effluent gas stream

  5. Magnetic properties of partially oxidized Fe films

    Science.gov (United States)

    Garcia, Miguel Angel; Lopez-Dominguez, Victor; Hernando, Antonio

    Hybrid magnetic nanostructures exhibit appealing properties due to interface and proximity effects. A simple and interesting system of hybrid magnetic nanomaterials are partially oxidized ferromagnetic films. We have fabricated Fe films by thermal evaporation and performed a partial oxidation to magnetite (Fe3O4) by annealing in air at different times and temperatures. The magnetic properties of the films evolve from those of pure metallic iron to pure magnetite, showing intermediate states where the proximity effects control the magnetic behavior. At some stages, the magnetization curves obtained by SQUID and MOKE magnetometry exhibit important differences due to the dissimilar contribution of both phases to the magneto-optical response of the system This work has been supported by the Ministerio Español de Economia y Competitividad (MINECO) MAT2013-48009-C4-1. V.L.D and M.A.G. acknowledges financial support from BBVA foundation.

  6. Reactor modeling and process analysis for partial oxidation of natural gas

    NARCIS (Netherlands)

    Albrecht, B.A.

    2004-01-01

    This thesis analyses a novel process of partial oxidation of natural gas and develops a numerical tool for the partial oxidation reactor modeling. The proposed process generates syngas in an integrated plant of a partial oxidation reactor, a syngas turbine and an air separation unit. This is called

  7. Partial oxidation of 2-propanol on perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Sumathi, R.; Viswanathan, B.; Varadarajan, T.K. [Indian Inst. of Tech., Madras (India). Dept. of Chemistry

    1998-12-31

    Partial oxidation of 2-propanol was carried out on AB{sub 1-x}B`{sub x}O{sub 3} (A=Ba, B=Pb, Ce, Ti; B`=Bi, Sb and Cu) type perovskite oxides. Acetone was the major product observed on all the catalysts. All the catalysts underwent partial reduction during the reaction depending on the composition of the reactant, nature of the B site cation and the extent of substitution at B site. The catalytic activity has been correlated with the reducibility of the perovskite oxides determined from Temperature Programmed Reduction (TPR) studies. (orig.)

  8. Bactericidal activity of partially oxidized nanodiamonds.

    Science.gov (United States)

    Wehling, Julia; Dringen, Ralf; Zare, Richard N; Maas, Michael; Rezwan, Kurosch

    2014-06-24

    Nanodiamonds are a class of carbon-based nanoparticles that are rapidly gaining attention, particularly for biomedical applications, i.e., as drug carriers, for bioimaging, or as implant coatings. Nanodiamonds have generally been considered biocompatible with a broad variety of eukaryotic cells. We show that, depending on their surface composition, nanodiamonds kill Gram-positive and -negative bacteria rapidly and efficiently. We investigated six different types of nanodiamonds exhibiting diverse oxygen-containing surface groups that were created using standard pretreatment methods for forming nanodiamond dispersions. Our experiments suggest that the antibacterial activity of nanodiamond is linked to the presence of partially oxidized and negatively charged surfaces, specifically those containing acid anhydride groups. Furthermore, proteins were found to control the bactericidal properties of nanodiamonds by covering these surface groups, which explains the previously reported biocompatibility of nanodiamonds. Our findings describe the discovery of an exciting property of partially oxidized nanodiamonds as a potent antibacterial agent.

  9. The chemical energy unit partial oxidation reactor operation simulation modeling

    Science.gov (United States)

    Mrakin, A. N.; Selivanov, A. A.; Batrakov, P. A.; Sotnikov, D. G.

    2018-01-01

    The chemical energy unit scheme for synthesis gas, electric and heat energy production which is possible to be used both for the chemical industry on-site facilities and under field conditions is represented in the paper. The partial oxidation reactor gasification process mathematical model is described and reaction products composition and temperature determining algorithm flow diagram is shown. The developed software product verification showed good convergence of the experimental values and calculations according to the other programmes: the temperature determining relative discrepancy amounted from 4 to 5 %, while the absolute composition discrepancy ranged from 1 to 3%. The synthesis gas composition was found out practically not to depend on the supplied into the partial oxidation reactor (POR) water vapour enthalpy and compressor air pressure increase ratio. Moreover, air consumption coefficient α increase from 0.7 to 0.9 was found out to decrease synthesis gas target components (carbon and hydrogen oxides) specific yield by nearly 2 times and synthesis gas target components required ratio was revealed to be seen in the water vapour specific consumption area (from 5 to 6 kg/kg of fuel).

  10. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  11. Electrochemical and partial oxidation of methane

    Science.gov (United States)

    Singh, Rahul

    2008-10-01

    negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by

  12. Development of a novel reactor concept for the partial oxidation of methane to syngas

    NARCIS (Netherlands)

    Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

    2004-01-01

    The gas-to-liquid process, consisting of the partial oxidation of methane (POM) followed by the Fischer-Tropsch reaction, is a promising alternative to conventional oil processing for the production of liquid fuels. The cost of a conventional POM process is mainly determined by cryogenic air

  13. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    Science.gov (United States)

    Opila, Elizabeth J.; Serra, Jessica

    2009-01-01

    Carbon-fiber reinforced SiC (C/SiC) composites are proposed for leading edge applications of hypersonic vehicles due to the superior strength of carbon fibers at high temperatures (greater than 1500 C). However, the vulnerability of the carbon fibers in C/SiC to oxidation over a wide range of temperatures remains a problem. Previous oxidation studies of C/SiC have mainly been conducted in air or oxygen, so that the oxidation behavior of C/SiC at reduced oxygen partial pressures of the hypersonic flight regime are less well understood. In this study, both carbon fibers and C/SiC composites were oxidized over a wide range of temperatures and oxygen partial pressures to facilitate the understanding and modeling of C/SiC oxidation kinetics for hypersonic flight conditions.

  14. 76 FR 55842 - Partial Approval and Partial Disapproval of Air Quality Implementation Plans; California; San...

    Science.gov (United States)

    2011-09-09

    ...; Reasonably Available Control Technology for Ozone AGENCY: Environmental Protection Agency (EPA). ACTION... CFR Part 52 Environmental protection, Air pollution control, Intergovernmental relations, Nitrogen... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 [EPA-R09-OAR-2011-0723; FRL-9462-3] Partial...

  15. Advances in the Partial Oxidation of Methane to Synthesis Gas

    Institute of Scientific and Technical Information of China (English)

    Quanli Zhu; Xutao Zhao; Youquan Deng

    2004-01-01

    The conversion and utilization of natural gas is of significant meaning to the national economy,even to the everyday life of people. However, it has not become a popular industrial process as expected due to the technical obstacles. In the past decades, much investigation into the conversion of methane,predominant component of natural gas, has been carried out. Among the possible routes of methane conversion, the partial oxidation of methane to synthesis gas is considered as an effective and economically feasible one. In this article, a brief review of recent studies on the mechanism of the partial oxidation of methane to synthesis gas together with catalyst development is wherein presented.

  16. Catalytic Partial Oxidation of Biomass/Oil Mixture

    Czech Academy of Sciences Publication Activity Database

    Veselý, Václav; Hanika, Jiří; Tukač, V.; Lederer, J.; Kovač, D.

    2013-01-01

    Roč. 7, č. 10 (2013), s. 1940-1945 ISSN 1934-8983 R&D Projects: GA TA ČR TE01020080; GA MPO 2A-2TP1/024 Institutional support: RVO:67985858 Keywords : hydrocarbon oil * biomass * catalytic partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.davidpublishing.com/journals_info.asp?jId=1718#

  17. Oxidative stress and partial migration in brown trout (Salmo trutta)

    DEFF Research Database (Denmark)

    Birnie-Gauvin, Kim; Peiman, K. S.; Larsen, Martin Hage

    2017-01-01

    of oxidative status in migration biology, particularly in fish. Semi-anadromous brown trout (Salmo trutta, Linnaeus 1758) exhibit partial migration, where some individuals smoltify and migrate to sea, and others become stream residents, providing us with an excellent model to investigate the link between...... oxidative stress and migration. Using the brown trout, we obtained blood samples from juveniles from a coastal stream in Denmark in the fall prior to peak seaward migration which occurs in the spring, and assayed for antioxidant capacity (oxygen radical absorbance capacity) and oxidative stress levels...

  18. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    NICOLAAS

    the water gas shift reaction with gold and ruthenium as the ... oven set at 100 °C, followed by calcination under the flow of air at. 500 °C. In the preparation of ..... for gold and ruthenium catalysts: behaviour in the water gas shift reaction, Appl.

  19. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  20. Thermal oxidation for air toxics control

    International Nuclear Information System (INIS)

    Pennington, R.L.

    1991-01-01

    The Administration projects annual expenditures of $1.1 billion by 1995, increasing to $6.7 billion by 2005, in order to comply with the new Clean Air Act Title III hazardous air pollutant requirements. The Title III requirements include 189 hazardous air pollutants which must be reduced or eliminated by 2003. Twenty of the 189 listed pollutants account for approximately 75 percent of all hazardous air pollutant emissions. Ninety percent of these 20 pollutants can be effectively controlled through one or mote of the thermal oxidation technologies. This paper reports that the advantages and disadvantages of each thermal oxidation technology vary substantially and must be reviewed for each application in order to establish the most effective thermal oxidation solution. Effective thermal oxidation will meet MACT (maximum achievable control technology) emission standards

  1. Interaction of dimethylamine with clean and partially oxidized copper surfaces

    Science.gov (United States)

    Kelber, J. A.; Rogers, J. W.; Banse, B. A.; Koel, B. E.

    1990-05-01

    The interaction of dimethylamine (DMA) with partially oxidized polycrystalline copper [Cu(poly)] and clean and partially oxidized Cu(110) between 110 and 500 K has been examined using electron stimulated desorption (ESD), high resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD). ESD mass spectra of the DMA adsorbed on O/Cu(poly) between 112 and 230 K consistently display peaks at 44 amu [(CH 3) 2N] + and 46 amu [(CH 3) 2NH-H] +, but no significant parent peak at 45 amu [(CH 3) 2NH] +, even though this last feature is prominent in the gas-phase mass spectrum. OH - is not observed at temperatures below 184 K and the yield at higher temperatures is much less than that of O +. HREELS of DMA on clean and oxygen covered Cu(110) obtained at temperatures between 100 and 320 K show characteristic vibrational spectra for molecular DMA and no OH(a) vibrational modes. TPD results show that the desorption profiles of all the major peaks in the DMA mass spectrum follow that of the parent peak with no evidence for production of H 2O. The ESD, HREELS and TPD results all indicate that DMA is molecularly and reversibly adsorbed, with no significant formation of surface hydroxyl species. The results indicate that preferential adsorption of amines from amine/epoxy mixtures onto metal oxide surfaces could passivate the surface and prevent subsequent bonding to the epoxy resin.

  2. Chemical polishing of partially oxidized T-111 alloy

    International Nuclear Information System (INIS)

    Teaney, P.E.

    1974-01-01

    The specimens were pressure-mounted in Bakelite and ground through 600 grit on silicon carbide papers. The specimens were rough-polished on a vibratory polisher for 4 to 6 h, using a water slurry of one micron alumina on Texmet, followed by 0.3-μ alumina on Texmet overnight. Final polishing was accomplished by continuous swabbing with a chemical polish. A chemical polish consisting of ten parts lactic acid, four parts nitric acid, and four parts hydrofluoric acid worked well for the T-111 parent material specimens; however, in the partially oxidized specimens, considerable pitting and staining occurred in the oxygen-affected zone and in the transition zone between the oxygen-affected zone and the parent material. A chemical polish was developed for the partially oxidized specimens by adjusting the ratio of the acids to ten parts lactic acid, two parts nitric acid, and two parts hydrofluoric acid. This slowed the chemical attack on the oxygen-affected zone considerably and, with continuous swabbing, the pitting and stain could be avoided. The specimens were rinsed and checked occasionally on the metallograph to determine when the proper polish had been obtained. Some specimens required intermittent polishing times up to 1 / 2 hour. No relationship could be established between the oxygen content of the specimen and the time required for chemical polishing in the partially oxidized specimens. However, the microstructure of the transition zone was the most difficult to obtain, and specimens with uniform reaction zones across the width of the specimen polished quicker than those with the transition zone

  3. Laser-induced partial oxidation of cyclohexane in liquid phase

    International Nuclear Information System (INIS)

    Oshima, Y.; Wu, X.W.; Koda, S.

    1995-01-01

    A laser-induced partial oxidation of cyclohexane was studied in the liquid phase. With KrF excimer laser (248 nm) irradiation to neat liquid cyclohexane in which O 2 was dissolved, cyclohexanol and cyclohexanone were obtained with very high selectivities, together with cyclohexane as a minor product. Radical recombination reactions to produce dicyclohexyl ether and bicyclohexyl also took place, while these products were not observed in the gas phase reaction. These experimental results were considered to be due not only to higher concentration of cyclohexane but to the cage effect in the liquid phase oxidation. To clarify the reaction progress including the photoabsorption process, the effects of laser intensity and O 2 pressure on product distribution were studied. (author)

  4. Oxidative Stress in Patients with Drug Resistant Partial Complex Seizure

    Directory of Open Access Journals (Sweden)

    Lourdes Lorigados Pedre

    2018-06-01

    Full Text Available Oxidative stress (OS has been implicated as a pathophysiological mechanism of drug-resistant epilepsy, but little is known about the relationship between OS markers and clinical parameters, such as the number of drugs, age onset of seizure and frequency of seizures per month. The current study’s aim was to evaluate several oxidative stress markers and antioxidants in 18 drug-resistant partial complex seizure (DRPCS patients compared to a control group (age and sex matched, and the results were related to clinical variables. We examined malondialdehyde (MDA, advanced oxidation protein products (AOPP, advanced glycation end products (AGEs, nitric oxide (NO, uric acid, superoxide dismutase (SOD, glutathione, vitamin C, 4-hydroxy-2-nonenal (4-HNE and nitrotyrosine (3-NT. All markers except 4-HNE and 3-NT were studied by spectrophotometry. The expressions of 4-HNE and 3-NT were evaluated by Western blot analysis. MDA levels in patients were significantly increased (p ≤ 0.0001 while AOPP levels were similar to the control group. AGEs, NO and uric acid concentrations were significantly decreased (p ≤ 0.004, p ≤ 0.005, p ≤ 0.0001, respectively. Expressions of 3-NT and 4-HNE were increased (p ≤ 0.005 similarly to SOD activity (p = 0.0001, whereas vitamin C was considerably diminished (p = 0.0001. Glutathione levels were similar to the control group. There was a positive correlation between NO and MDA with the number of drugs. The expression of 3-NT was positively related with the frequency of seizures per month. There was a negative relationship between MDA and age at onset of seizures, as well as vitamin C with seizure frequency/month. We detected an imbalance in the redox state in patients with DRCPS, supporting oxidative stress as a relevant mechanism in this pathology. Thus, it is apparent that some oxidant and antioxidant parameters are closely linked with clinical variables.

  5. Modeling of termokinetic oscillations at partial oxidation of methane

    Science.gov (United States)

    Arutyunov, A. V.; Belyaev, A. A.; Inovenkov, I. N.; Nefedov, V. V.

    2017-12-01

    Partial oxidation of natural gas at moderate temperatures below 1500 K has significant interest for a number of industrial applications. But such processes can proceed at different unstable regimes including oscillating modes. Nonlinear phenomena at partial oxidation of methane were observed at different conditions. The investigation of the complex nonlinear system of equations that describes this process is a real method to insure its stability at industrial conditions and, at the same time, is an effective tool for its further enhancement. Numerical analysis of methane oxidation kinetics in the continuous stirred-tank reactor, with the use of detailed kinetic model has shown the possibility of the appearance of oscillating modes in the appropriate range of reaction parameters that characterize the composition, pressure, reagents flow, thermophysical features of the system, and geometry of the reactor. The appearance of oscillating modes is connected both with the reaction kinetics, heat release and sink and reagents introduction and removing. At that, oscillations appear only at a limited range of parameters, but can be accompanied by significant change in the yield of products. We have determined the range of initial temperature and pressure at which oscillations can be observed, if all other parameters remained fixed. The boundaries of existence of oscillations on the phase plane were calculated. It was shown that depending on the position inside the oscillation region the oscillations have different frequency and amplitude. It was reviled the role of heat exchange with the environment: at the absence of heat exchange the oscillating modes are impossible. In the vicinity of the boundary of phase range, where oscillations exist, significant change of concentration of some products were observed, for example, that of CO2, which in this case one of the principal products is. At that, insignificant increase in pressure not only change the character of CO2 behaving

  6. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite

    International Nuclear Information System (INIS)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H.

    2014-01-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  7. Bimetallic catalysts for continuous catalytic wet air oxidation of phenol.

    Science.gov (United States)

    Fortuny, A; Bengoa, C; Font, J; Fabregat, A

    1999-01-29

    Catalytic wet oxidation has proved to be effective at eliminating hazardous organic compounds, such as phenol, from waste waters. However, the lack of active long-life oxidation catalysts which can perform in aqueous phase is its main drawback. This study explores the ability of bimetallic supported catalysts to oxidize aqueous phenol solutions using air as oxidant. Combinations of 2% of CoO, Fe2O3, MnO or ZnO with 10% CuO were supported on gamma-alumina by pore filling, calcined and later tested. The oxidation was carried out in a packed bed reactor operating in trickle flow regime at 140 degrees C and 900 kPa of oxygen partial pressure. Lifetime tests were conducted for 8 days. The pH of the feed solution was also varied. The results show that all the catalysts tested undergo severe deactivation during the first 2 days of operation. Later, the catalysts present steady activity until the end of the test. The highest residual phenol conversion was obtained for the ZnO-CuO, which was significantly higher than that obtained with the 10% CuO catalyst used as reference. The catalyst deactivation is related to the dissolution of the metal oxides from the catalyst surface due to the acidic reaction conditions. Generally, the performance of the catalysts was better when the pH of the feed solution was increased.

  8. Production of reduction gases: partial oxidation of hydrocarbons and coal

    Energy Technology Data Exchange (ETDEWEB)

    Tippmer, K

    1976-04-01

    After some general remarks on reduction gas and quality demands, the Texaco process of partial oxidation with scrubbing is dealt with. A comparison of current iron-sponge techniques shows that a heat demand below 3 M kcal/t Fe should be envisaged, which means that heavy fuel oil or coal should be used. The special features of oxygen generation, coal processing, demands made on fuel oil, gasoline, and natural gas, gas generation, soot recovery, hydrogen sulphide-carbon dioxide scrubbing, system Benfield HP process, recycle-carbon dioxide scrubbing, auxiliary steam system, gas preheating, recycle gas cooling and compression, process data and heat balances for natural gas (one-heat system) and heating fuel oil or naphtha (two-heat system) are given.

  9. Traffic air pollution and oxidized LDL.

    Directory of Open Access Journals (Sweden)

    Lotte Jacobs

    Full Text Available BACKGROUND: Epidemiologic studies indirectly suggest that air pollution accelerates atherosclerosis. We hypothesized that individual exposure to particulate matter (PM derived from fossil fuel would correlate with plasma concentrations of oxidized low-density lipoprotein (LDL, taken as a marker of atherosclerosis. We tested this hypothesis in patients with diabetes, who are at high risk for atherosclerosis. METHODOLOGY/PRINCIPAL FINDINGS: In a cross-sectional study of non-smoking adult outpatients with diabetes we assessed individual chronic exposure to PM by measuring the area occupied by carbon in airway macrophages, collected by sputum induction and by determining the distance from the patient's residence to a major road, through geocoding. These exposure indices were regressed against plasma concentrations of oxidized LDL, von Willebrand factor and plasminogen activator inhibitor 1 (PAI-1. We could assess the carbon load of airway macrophages in 79 subjects (58 percent. Each doubling in the distance of residence from major roads was associated with a 0.027 µm(2 decrease (95% confidence interval (CI: -0.048 to -0.0051 in the carbon load of airway macrophages. Independently from other covariates, we found that each increase of 0.25 µm(2 [interquartile range (IQR] in carbon load was associated with an increase of 7.3 U/L (95% CI: 1.3 to 13.3 in plasma oxidized LDL. Each doubling in distance of residence from major roads was associated with a decrease of -2.9 U/L (95% CI: -5.2 to -0.72 in oxidized LDL. Neither the carbon load of macrophages nor the distance from residence to major roads, were associated with plasma von Willebrand factor or PAI-1. CONCLUSIONS: The observed positive association, in a susceptible group of the general population, between plasma oxidized LDL levels and either the carbon load of airway macrophages or the proximity of the subject's residence to busy roads suggests a proatherogenic effect of traffic air pollution.

  10. Development of a Catalytic Wet Air Oxidation Method to Produce Feedstock Gases from Waste Polymers

    Science.gov (United States)

    Kulis, Michael J.; Guerrero-Medina, Karen J.; Hepp, Aloysius F.

    2012-01-01

    Given the high cost of space launch, the repurposing of biological and plastic wastes to reduce the need for logistical support during long distance and long duration space missions has long been recognized as a high priority. Described in this paper are the preliminary efforts to develop a wet air oxidation system in order to produce fuels from waste polymers. Preliminary results of partial oxidation in near supercritical water conditions are presented. Inherent corrosion and salt precipitation are discussed as system design issues for a thorough assessment of a second generation wet air oxidation system. This work is currently being supported by the In-Situ Resource Utilization Project.

  11. Method and apparatus for monitoring oxygen partial pressure in air masks

    Science.gov (United States)

    Kelly, Mark E. (Inventor); Pettit, Donald R. (Inventor)

    2006-01-01

    Method and apparatus are disclosed for monitoring an oxygen partial pressure in an air mask and providing a tactile warning to the user. The oxygen partial pressure in the air mask is detected using an electrochemical sensor, the output signal from which is provided to a comparator. The comparator compares the output signal with a preset reference value or range of values representing acceptable oxygen partial pressures. If the output signal is different than the reference value or outside the range of values, the air mask is vibrated by a vibrating motor to alert the user to a potentially hypoxic condition.

  12. Generation of synthesis gas by partial oxidation of natural gas in a gas turbine

    NARCIS (Netherlands)

    Cornelissen, R.; Tober, E.; Kok, Jacobus B.W.; van der Meer, Theodorus H.

    2006-01-01

    The application of partial oxidation in a gas turbine (PO-GT) in the production of synthesis gas for methanol production is explored. In PO-GT, methane is compressed, preheated, partial oxidized and expanded. For the methanol synthesis a 12% gain in thermal efficiency has been calculated for the

  13. Mixed conducting materials for partial oxidation of hydrocarbons

    Directory of Open Access Journals (Sweden)

    Frade, J. R.

    2004-06-01

    Full Text Available Thermodynamic calculations with additional conditions for the conservation of carbon and hydrogen were used to predict the gas composition obtained by partial oxidation of methane as a function of oxygen partial pressure and temperature; this was used to assess the stability and oxygen permeability requirements of mixed conducting membrane materials proposed for this purpose. A re-examination of known mixed conductors shows that most materials with highest permeability still fail to fulfil the requirements of stability under reducing conditions. Other materials possess sufficient stability but their oxygen permeability is insufficient. Different approaches were thus used to attempt to overcome those limitations, including changes in composition in the A and B site positions of ABO3 perovskites, and tests of materials with different structure types. Promising results were obtained mainly for some materials with perovskite or related K2NiF4-type structures. Limited stability of the most promising materials shows that one should rely mainly on kinetic limitations in the permeate side to protect the mixed conductor from severe reducing conditions.

    Se han usado cálculos termodinámicos con condiciones adicionales para la conservación del carbono e hidrógeno para predecir la composición del gas obtenido mediante la oxidación parcial del metano en función de la presión parcial de oxígeno y de la temperatura; esto se ha usado para asegurar los requerimientos de estabilidad y permeabilidad al oxígeno de los materiales conductores mixtos empleados como membrana para este propósito. Un nuevo exámen de los conductores mixtos conocidos muestra que la mayoría de los materiales con la mayor permeabilidad todavía fallan en el cumplimiento de los requerimientos de estabilidad bajo condiciones reductoras. Otros materiales poseen suficiente estabilidad, pero su permeabilidad al oxígeno es insuficiente. Por ello se han empleado diferentes

  14. Steam and partial oxidation reforming options for hydrogen production from fossil fuels for PEM fuel cells

    Directory of Open Access Journals (Sweden)

    Yousri M.A. Welaya

    2012-06-01

    Full Text Available Proton exchange membrane fuel cell (PEM generates electrical power from air and from hydrogen or hydrogen rich gas mixtures. Therefore, there is an increasing interest in converting current hydrocarbon based marine fuels such as natural gas, gasoline, and diesel into hydrogen rich gases acceptable to the PEM fuel cells on board ships. Using chemical flow sheeting software, the total system efficiency has been calculated. Natural gas appears to be the best fuel for hydrogen rich gas production due to its favorable composition of lower molecular weight compounds. This paper presents a study for a 250 kW net electrical power PEM fuel cell system utilizing a partial oxidation in one case study and steam reformers in the second. This study has shown that steam-reforming process is the most competitive fuel processing option in terms of fuel processing efficiency. Partial oxidation process has proved to posses the lowest fuel processing efficiency. Among the options studied, the highest fuel processing efficiency is achieved with natural gas steam reforming system.

  15. Enhanced performance of solid oxide electrolysis cells by integration with a partial oxidation reactor: Energy and exergy analyses

    International Nuclear Information System (INIS)

    Visitdumrongkul, Nuttawut; Tippawan, Phanicha; Authayanun, Suthida; Assabumrungrat, Suttichai; Arpornwichanop, Amornchai

    2016-01-01

    Highlights: • Process design of solid oxide electrolyzer integrated with a partial oxidation reactor is studied. • Effect of key operating parameters of partial oxidation reactor on the electrolyzer performance is presented. • Exergy analysis of the electrolyzer process is performed. • Partial oxidation reactor can enhance the solid oxide electrolyzer performance. • Partial oxidation reactor in the process is the highest exergy destruction unit. - Abstract: Hydrogen production without carbon dioxide emission has received a large amount of attention recently. A solid oxide electrolysis cell (SOEC) can produce pure hydrogen and oxygen via a steam electrolysis reaction that does not emit greenhouse gases. Due to the high operating temperature of SOEC, an external heat source is required for operation, which also helps to improve SOEC performance and reduce operating electricity. The non-catalytic partial oxidation reaction (POX), which is a highly exothermic reaction, can be used as an external heat source and can be integrated with SOEC. Therefore, the aim of this work is to study the effect of operating parameters of non-catalytic POX (i.e., the oxygen to carbon ratio, operating temperature and pressure) on SOEC performance, including exergy analysis of the process. The study indicates that non-catalytic partial oxidation can enhance the hydrogen production rate and efficiency of the system. In terms of exergy analysis, the non-catalytic partial oxidation reactor is demonstrated to be the highest exergy destruction unit due to irreversible chemical reactions taking place, whereas SOEC is a low exergy destruction unit. This result indicates that the partial oxidation reactor should be improved and optimally designed to obtain a high energy and exergy system efficiency.

  16. Enhanced wet air oxidation : synergistic rate acceleration upon effluent recirculation

    Science.gov (United States)

    Matthew J. Birchmeier; Charles G. Hill; Carl J. Houtman; Rajai H. Atalla; Ira A. Weinstock

    2000-01-01

    Wet air oxidation (WAO) reactions of cellobiose, phenol, and syringic acid were carried out under mild conditions (155°C; 0.93MPa 02; soluble catalyst, Na5[PV2Mo10O40]). Initial oxidation rates were rapid but decreased to small values as less reactive oxidation products accumulated. Recalcitrant oxidation products were consumed more rapidly, however, if additional...

  17. Investigation of flow condition on the oxidation of Zircaloy-4 in air at 850 and 1100 .deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Maeng, Yun Hwan; Lee, Jae Young [Hangdong Global University, Pohang (Korea, Republic of); Park, Sang Gil [ACT Co. Ltd, Daejeon (Korea, Republic of)

    2016-05-15

    An oxidation behavior of the Zircaloy-4 was experimentally studied by varying a flow rate and partial pressure of air. Tests were conducted at two distinct temperatures in which a kinetic transition was occurred, or not: 850 .deg. C and 1100 .deg. C. The effects of flow rate and partial pressure of air was studied by a measurement of mass gain using thermogravimetric analyzer (TGA). After experiments, samples were observed with macrophotography and metallography using optical microscopy. The effect of flow rate and partial pressure of air were qualitatively analyzed with those methods. The effects of flow conditions on the oxidation kinetics of Zircaloy-4 samples were qualitatively studied. The flow rate and the partial pressure of air were changed and their effects was different when the temperature was changed.

  18. Effects of oxygen partial pressure on Li-air battery performance

    Science.gov (United States)

    Kwon, Hyuk Jae; Lee, Heung Chan; Ko, Jeongsik; Jung, In Sun; Lee, Hyun Chul; Lee, Hyunpyo; Kim, Mokwon; Lee, Dong Joon; Kim, Hyunjin; Kim, Tae Young; Im, Dongmin

    2017-10-01

    For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we have investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which has not been systematically examined. The amounts of consumed O2 and evolved CO2 from the Li-air cell are measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio is attained under 70% O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70% O2 condition. Overall, an oxygen partial pressure of about 0.5-0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.

  19. Effects of adsorbates on Zircaloy oxidation in air

    International Nuclear Information System (INIS)

    Cho, Y.; Kim, Y-G.; Park, K.

    1997-01-01

    The air-oxidation of Zry and the effects of adsorbates on the oxidation are found by the intermittent measurement of the weight gain of specimens. NaC1 enhances the oxidation, where nonuniform stresses on the surface and C1 ions are the cause. LiOH also enhances the oxidation, where the initial oxide formed by LiOH seems to the reason. The effects of fluorides on oxidation are also measured. NaF is most harmful and KF follows next. LiF does not effect the oxidation of Zry. Diffusion of fluorides in oxide determines the enhancement. (author)

  20. Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming; Cha, Min

    2015-01-01

    We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight

  1. Hydrogen or Soot?: Partial Oxidation of High-boiling Hydrocarbon Wastes

    Czech Academy of Sciences Publication Activity Database

    Lederer, J.; Hanika, Jiří; Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, Václav

    2015-01-01

    Roč. 29, č. 1 (2015), s. 5-11 ISSN 0352-9568 Institutional support: RVO:67985858 Keywords : partial oxidation * waste * hydrocarbon Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.675, year: 2015

  2. The production of hydrogen through the uncatalyzed partial oxidation of methane in an internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Ghazi A.; Wierzba, I. [Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary (Canada)

    2008-04-15

    The thermodynamic and kinetic limitations of the uncatalyzed partial oxidation of methane for the production of synthesis gas, which is made up of mostly hydrogen and carbon monoxide in a variety of proportions, are reviewed. It is suggested that such processes can be made to proceed successfully in a conventional internal combustion engine when operated on excessively rich mixtures of methane and oxygenated air. This is achieved while simultaneously producing power and regenerative exhaust gas heating. Experimental results are described that show a dual fuel engine of the compression ignition type with pilot liquid fuel injection can be operated on excessively rich mixtures of methane and air supplemented with oxygen gas to produce hydrogen rich gas with high methane conversion rates. Similarly, a spark ignition engine was reported to be equally capable of such production and performance. It is shown that there are viable prospects for the simultaneous production of synthesis gas in engines with efficient useful mechanical power and exhaust gas regenerative heating. (author)

  3. Simulation study of a PEM fuel cell system fed by hydrogen produced by partial oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ozdogan, S [Marmara University, Faculty of Engineering, Istanbul (Turkey); Ersoz, A; Olgun, H [TUBITAK Marmara Research Center, Energy Systems and Environmental Research Institute, Kocaeli (Turkey)

    2003-09-01

    Within the frame of sustainable development, efficient and clean, if possible zero emission energy production technologies are of utmost importance in various sectors such as utilities, industry, households and transportation. Low-temperature fuel cell systems are suitable for powering transportation systems such as automobiles and trucks in an efficient and low-emitting manner. Proton exchange membrane (PEM) fuel cell systems constitute the most promising low temperature fuel cell option being developed globally. PEM fuel cells generate electric power from air and hydrogen or from a hydrogen rich gas via electrochemical reactions. Water and waste heat are the only by-products of PEM fuel cells. There is great interest in converting current hydrocarbon based common transportation fuels such as gasoline and diesel into hydrogen rich gases acceptable by PEM fuel cells. Hydrogen rich gases can be produced from conventional transportation fuels via various reforming technologies. Steam reforming, partial oxidation and auto-thermal reforming are the three major reforming technologies. In this paper, we discuss the results of a simulation study for a PEM fuel cell with partial oxidation. The Aspen HYSYS 3.1 code has been used for simulation purposes. Two liquid hydrocarbon fuels have been selected to investigate the effect of average molecular weights of hydrocarbons, on the fuel processing efficiency. The overall system efficiency depends on the fuel preparation and fuel cell efficiencies as well as on the heat integration within the system. It is desired to investigate the overall system efficiencies for net electrical power production at 100 kW considering bigger scale transport applications. Results indicate that fuel properties, fuel preparation system operating parameters and PEM fuel cell polarization curve characteristics all affect the overall system efficiency. (authors)

  4. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  5. Partial camera automation in an unmanned air vehicle.

    Science.gov (United States)

    Korteling, J E; van der Borg, W

    1997-03-01

    The present study focused on an intelligent, semiautonomous, interface for a camera operator of a simulated unmanned air vehicle (UAV). This interface used system "knowledge" concerning UAV motion in order to assist a camera operator in tracking an object moving through the landscape below. The semiautomated system compensated for the translations of the UAV relative to the earth. This compensation was accompanied by the appropriate joystick movements ensuring tactile (haptic) feedback of these system interventions. The operator had to superimpose self-initiated joystick manipulations over these system-initiated joystick motions in order to track the motion of a target (a driving truck) relative to the terrain. Tracking data showed that subjects performed substantially better with the active system. Apparently, the subjects had no difficulty in maintaining control, i.e., "following" the active stick while superimposing self-initiated control movements over the system-interventions. Furthermore, tracking performance with an active interface was clearly superior relative to the passive system. The magnitude of this effect was equal to the effect of update-frequency (2-5 Hz) of the monitor image. The benefits of update frequency enhancement and semiautomated tracking were the greatest under difficult steering conditions. Mental workload scores indicated that, for the difficult tracking-dynamics condition, both semiautomation and update frequency increase resulted in less experienced mental effort. For the easier dynamics this effect was only seen for update frequency.

  6. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1993-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  7. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1994-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  8. Comparison between zircaloy oxidation in steam and air surroundings

    International Nuclear Information System (INIS)

    Shawkat, M.E.; Hasaneln, H.; Ali, M.; Parlatan, Y.; Albasha, H.

    2013-01-01

    The available experimental data for Zircaloy oxidation in air were reviewed. The behavior of the oxidation kinetics at different temperature ranges was described. It was shown that maintaining the oxidation kinetics within the oxide pre-breakaway region can prevent elevated sheath temperatures due to the oxidation process during postulated accidents. The available correlations to model the oxidation kinetics for pre-breakaway region were reviewed and assessed. Zircaloy-air oxidation correlation based on Leistikow-Berg data was determined to be the most suitable correlation to model pre-breakaway kinetics and it was compared to Urbanic-Heidrick correlation which is widely used for Zircaloy oxidation in steam environment. The results showed that the energy release due to the Zircaloy-steam oxidation bounds the energy released due to Zircaloy-air oxidation up to a sheath temperature referred as the “crossover temperature”. Below this temperature, the impact of Zircaloy-air oxidation on fuel sheath temperature transient can be predicted conservatively using the Urbanic-Heidrick steam correlation. The crossover temperature was calculated for isothermal sheath heating as well as transient sheath heat-up assuming three linear heating rates of 0.6, 1.0, and 1.3 K/s. (author)

  9. Wet-air oxidation cleans up black wastewater

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    Sterling Organics produces the analgesic paracetamol (acetaminophen) at its Dudley, England, plant. The wastewater from the batch process contains intermediates such as para-aminophenol (PAP) and byproducts such as thiosulfates, sulfites and sulfides. To stay ahead of increasingly strict environmental legislation, Sterling Organics installed a wet-air oxidation system at the Dudley facility in August 1992. The system is made by Zimpro Environmental Inc. (Rothschild, Wis.). Zimpro's wet-air oxidation system finds a way around the limitations of purely chemical or physical processes. In the process, compressed air at elevated temperature and pressure oxidizes the process intermediates and byproducts and removes the color from the wastewater.

  10. Direct Partial Oxidation of Natural Gas to Liquid Chemicals

    DEFF Research Database (Denmark)

    Rasmussen, Christian Lund

    2007-01-01

    Direkte delvis oxidation af naturgas til flydende kemikalier er en attraktiv industriel proces, hvor naturgas omdannes til stoffer; primært methanol (CH3OH) som let kan transporteres over store afstande. Omdannelsen sker i en simpel et-trinsproces under højt tryk, lave forbrændingstemperaturer, s...

  11. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  12. Air Quality Criteria for Sulfur Oxides.

    Science.gov (United States)

    National Air Pollution Control Administration (DHEW), Washington, DC.

    Included is a literature review which comprehensively discusses knowledge of the sulfur oxides commonly found in the atmosphere. The subject content is represented by the 10 chapter titles: Physical and Chemical Properties and the Atmospheric Reactions of the Oxides of Sulfur; Sources and Methods of Measurements of Sulfur Oxides in the Atmosphere;…

  13. Experimental investigation and thermodynamic simulation of the uranium oxide-zirconium oxide-iron oxide system in air

    Czech Academy of Sciences Publication Activity Database

    Petrov, Y. B.; Udalov, Y. P.; Šubrt, Jan; Bakardjieva, Snejana; Sázavský, P.; Kiselová, M.; Selucký, P.; Bezdička, Petr; Joumeau, C.; Piluso, P.

    2011-01-01

    Roč. 37, č. 2 (2011), s. 212-229 ISSN 1087-6596 Institutional research plan: CEZ:AV0Z40320502 Keywords : uranium oxide * zirconium oxide * iron oxide * fusibility curve * oxygen partial pressure * crystallization * phase composition Subject RIV: CA - Inorganic Chemistry Impact factor: 0.492, year: 2011

  14. Exploring the chemical kinetics of partially oxidized intermediates by combining experiments, theory, and kinetic modeling.

    Science.gov (United States)

    Hoyermann, Karlheinz; Mauß, Fabian; Olzmann, Matthias; Welz, Oliver; Zeuch, Thomas

    2017-07-19

    Partially oxidized intermediates play a central role in combustion and atmospheric chemistry. In this perspective, we focus on the chemical kinetics of alkoxy radicals, peroxy radicals, and Criegee intermediates, which are key species in both combustion and atmospheric environments. These reactive intermediates feature a broad spectrum of chemical diversity. Their reactivity is central to our understanding of how volatile organic compounds are degraded in the atmosphere and converted into secondary organic aerosol. Moreover, they sensitively determine ignition timing in internal combustion engines. The intention of this perspective article is to provide the reader with information about the general mechanisms of reactions initiated by addition of atomic and molecular oxygen to alkyl radicals and ozone to alkenes. We will focus on critical branching points in the subsequent reaction mechanisms and discuss them from a consistent point of view. As a first example of our integrated approach, we will show how experiment, theory, and kinetic modeling have been successfully combined in the first infrared detection of Criegee intermediates during the gas phase ozonolysis. As a second example, we will examine the ignition timing of n-heptane/air mixtures at low and intermediate temperatures. Here, we present a reduced, fuel size independent kinetic model of the complex chemistry initiated by peroxy radicals that has been successfully applied to simulate standard n-heptane combustion experiments.

  15. Experimental and simulation analysis of hydrogen production by partial oxidation of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Sikander, U. [National Univ. of Science and Technology, Islamabad (Pakistan)

    2014-10-15

    Partial oxidation of methanol is the only self-sustaining process for onboard production of hydrogen. For this a fixed bed catalytic reactor is designed, based on heterogeneous catalytic reaction. To develop an optimized process, simulation is carried out using ASPEN HYSYS v 7.1. Reaction kinetics is developed on the basis of Langmuir Hinshel wood model. 45:55:5 of CuO: ZnO: Al/sub 2/O/sub 3/ is used as a catalyst. Simulation results are studied in detail to understand the phenomenon of partial oxidation of methanol inside the reactor. An experimental rig is developed for hydrogen production through partial oxidation of methanol. Results obtained from process simulation and experimental work; are compared with each other. (author)

  16. Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2015-01-01

    We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight from studying high-temperature and low-pressure conditions with similar reduced field intensities. In the tested range of background temperatures (297 < T < 773 K), we found that the conversion of methane and oxygen depended on both the electron-induced chemistry and the thermo-chemistry, whereas the chemical pathways to the products were overall controlled by the thermo-chemistry at a given temperature. We also found that the thermo-chemistry enhanced the plasma-assisted partial oxidation process. Our findings expand our understanding of the plasma-assisted partial oxidation process and may be helpful in the design of cost-effective plasma reformers. © 2014 The Combustion Institute.

  17. The Oxides of Nitrogen in Air Pollution.

    Science.gov (United States)

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  18. Effect of oxygen partial pressure on oxidation of Mo-metal

    Science.gov (United States)

    Sharma, Rabindar Kumar; Kumar, Prabhat; Singh, Megha; Gopal, Pawar; Reddy, G. B.

    2018-05-01

    This report explains the effect of oxygen partial pressure (PO2 ) on oxidation of Mo-metal in oxygen plasma. XRD results indulge that oxide layers formed on Mo-surfaces at different oxygen partial pressures have two different oxide phases (i.e. orthorhombic MoO3 and monoclinic Mo8O23). Intense XRD peaks at high pressure (i.e. 2.0×10-1 Torr) points out the formation of thick oxide layer on Mo-surface due to presence of large oxygen species in chamber and less oxide volatilization. Whereas, at low PO2 (6.5×10-2 and 7.5×10-2 Torr.) the reduced peak strength is owing to high oxide volatilization rate. SEM micrographs and thickness measurements also support XRD results and confirm that the optimum -2value of PO2 to deposited thicker and uniform oxide film on glass substrate is 7.5×10-2 Torr through plasma assistedoxidation process. Further to study the compositional properties, EDX of the sample M2 (the best sample) is carried out, which confirms that the stoichiometric ratio is less than 3 (i.e. 2.88). Less stoichiometric ratio again confirms the presence of sub oxides in oxide layers on Mo metal as evidenced by XRD results. All the observed results are well in consonance with each other.

  19. A simple air sampling technique for monitoring nitrous oxide pollution

    Energy Technology Data Exchange (ETDEWEB)

    Austin, J C; Shaw, R; Moyes, D; Cleaton-Jones, P E

    1981-01-01

    A simple, inexpensive device for the continuous low-flow sampling of air was devised to permit monitoring of pollution by gaseous anaesthetics. The device consisted of a water-filled Perspex cylinder in which a double-walled flexible-film gas sample collection bag was suspended. Air samples could be aspirated into the collection bag at flow rates of as low as 1 ml min-1 by allowing the water to drain from the cylinder at a controlled rate. The maintenance of sample integrity with aspiration and storage of samples of nitrous oxide in air at concentrations of 1000, 100 and 30 p.p.m. v/v was examined using gas chromatography. The sample bags retained a mean 94% of the nitrous oxide in air samples containing nitrous oxide 25 p.p.m. over a 72-h storage period.

  20. Ce-Fe-O mixed oxide as oxygen carrier for the direct partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    魏永刚; 王华; 李孔斋

    2010-01-01

    The Ce-Fe-O mixed oxide with a ratio of Ce/Fe=7:3, which was prepared by coprecipitation method and employed as oxygen carrier, for direct partial oxidation of methane to syngas in the absence of gaseous oxygen was explored. The mixed oxide was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the catalytic performances were studied in a fixed-bed quartz reactor and a thermogravimetric reactor, respectively. Approximately 99.4% H2 se...

  1. Direct Partial Oxidations Using Molecular Oxygen - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Richard [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-11-01

    In 2006, Richard A. Kemp (University of New Mexico) and Karen I. Goldberg (University of Washington) formed a team and began to investigate new strategies to accomplish direct selective aerobic oxidations, with a particular emphasis on the epoxidation of propylene and higher olefins. This DOE-BES funded project was renewed twice and concluded after a no-cost extension earlier this year. Multiple novel strategies involving homogeneous catalyst systems were initiated and investigated during the award. Important fundamental understanding and insight concerning requirements for promotion of aerobic olefin epoxidation was generated. During the tenure of this project, new knowledge was generated concerning the synthesis, characterization and aerobic reactivity of metal hydrides and hydroxides. Key results describing synthetic strategies and optimization of the preparation of mononuclear late metal hydrides were published. The team reported the first example of O2 insertion into a Pd-H bond, a reaction which had been proposed in the literature but never previously observed. Our experimental investigation of the mechanism was later followed by computational work, and a description of what is now referred to as the Hydrogen Atom Abstraction (HAA) pathway for this reaction has been widely accepted in the community. After investigation of many other late metal hydrides, both experimentally and computationally, the team put together a chapter that included a description of key contributing factors that allow reaction by the HAA mechanism. A brief sampling of other classic papers from our project include hydrogenolysis reactions of late metal hydroxide and alkoxide complexes, the synthesis of nickel-hydrides, and the involvement of hemilabile ligands in promoting new reaction pathways.

  2. Modelling of the partial oxidation of {alpha}, {beta}-unsaturated aldehydes on Mo-V-oxides based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, H.; Petzoldt, J.C.; Stein, B.; Weimer, C.; Gaube, J.W. [Technische Univ. Darmstadt (Germany). Inst. fuer Chemische Technologie

    1998-12-31

    A kinetic model based on the Mars-van Krevelen mechanism that allows to describe the microkinetics of the heterogeneously catalysed partial oxidation of {alpha}, {beta}-unsaturated aldehydes is presented. This conversion is represented by a network, composed of the oxidation of the {alpha}, {beta}-unsaturated aldehyde towards the {alpha}, {beta}-unsaturated carboxylic acid and the consecutive oxidation of the acid as well as the parallel reaction of the aldehyde to products of deeper oxidation. The reaction steps of aldehyde respectively acid oxidation and catalyst reoxidation have been investigated separately in transient experiments. The combination of steady state and transient experiments has led to an improved understanding of the interaction of the catalyst with the aldehyde and the carboxylic acids as well as to a support of the kinetic model assumptions. (orig.)

  3. Reaction scheme of partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia

    NARCIS (Netherlands)

    Zhu, J.J.; van Ommen, J.G.; Lefferts, Leonardus

    2004-01-01

    The partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia (YSZ) was studied with in situ FTIR and both steady-state and transient experiments. The four major products, CO, H2, CO2, and H2O, are primary products of CPOM over YSZ. Besides these major products and traces of

  4. The influence of partial oxidation mechanisms on tar destruction in TwoStage biomass gasification

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Egsgaard, Helge; Stelte, Wolfgang

    2013-01-01

    adsorption and determined by stable isotope dilution analysis. The results have shown that partial oxidation reduces and converts primary tars into low molecular weight, polycyclic aromatic hydrocarbons (PAHs), primarily naphthalene. At temperatures above 950°C practically all phenol is converted...

  5. Modelling of a reverse flow catalytic membrane reactor for the partial oxidation of methane

    NARCIS (Netherlands)

    Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

    2003-01-01

    Gas-To-Liquid (GTL) processes have great potential as alternative to conventional oil and coal processing for the production of liquid fuels. In GTL-processes the partial oxidation of methane (POM) is combined with the Fischer-Tropsch reaction. An important part of the investment costs of a

  6. Partial Oxidation of High-Boiling Hydrocarbon Mixtures in the Pilot Unit

    Czech Academy of Sciences Publication Activity Database

    Hanika, Jiří; Lederer, J.; Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, Václav

    2014-01-01

    Roč. 68, č. 12 (2014), s. 1701-1706 ISSN 0366-6352 Institutional support: RVO:67985858 Keywords : partial oxidation * high-boiling hydrocarbons * pilot plant Subject RIV: CI - Industrial Chemistry , Chemical Engineering Impact factor: 1.468, year: 2014

  7. Hydrogen generator, via catalytic partial oxidation of methane for fuel cells

    Science.gov (United States)

    Recupero, Vincenzo; Pino, Lidia; Di Leonardo, Raffaele; Lagana', Massimo; Maggio, Gaetano

    It is well known that the most acknowledged process for generation of hydrogen for fuel cells is based upon the steam reforming of methane or natural gas. A valid alternative could be a process based on partial oxidation of methane, since the process is mildly exothermic and therefore not energy intensive. Consequently, great interest is expected from conversion of methane into syngas, if an autothermal, low energy intensive, compact and reliable process could be developed. This paper covers the activities, performed by the CNR Institute of Transformation and Storage of Energy (CNR-TAE), on theoretical and experimental studies for a compact hydrogen generator, via catalytic selective partial oxidation of methane, integrated with second generation fuel cells (EC-JOU2 contract). In particular, the project focuses the attention on methane partial oxidation via heterogeneous selective catalysts, in order to: demonstrate the basic catalytic selective partial oxidation of methane (CSPOM) technology in a subscale prototype, equivalent to a nominal output of 5 kWe; develop the CSPOM technology for its application in electric energy production by means of fuel cells; assess, by a balance of plant analysis, and a techno-economic evaluation, the potential benefits of the CSPOM for different categories of fuel cells.

  8. Kinetics of the partial oxidation of methanol over a Fe-Mo catalyst

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Sint Annaland, van M.; Kuipers, J.A.M.

    2005-01-01

    The intrinsic steady-state kinetics of the partial oxidation of methanol to formaldehyde over a commercial Fe-Mo catalyst has been studied experimentally in a differentially operated reactor at temperatures of 230–260 °C, over a wide range of methanol and oxygen concentrations. The principal

  9. Kinetics of the partial oxidation of methanol over a Fe-Mo catalyst

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; van Sint Annaland, M.; Kuipers, J.A.M.

    2005-01-01

    The intrinsic steady-state kinetics of the partial oxidation of methanol to formaldehyde over a commercial Fe-Mo catalyst has been studied experimentally in a differentially operated reactor at temperatures of 230¿260 °C, over a wide range of methanol and oxygen concentrations. The principal

  10. Oxygen partial pressure: a key to alloying and discovery in metal oxide--metal eutectic systems

    International Nuclear Information System (INIS)

    Holder, J.D.; Clark, G.W.; Oliver, B.F.

    1978-01-01

    Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Po 2 sensitive as are melt stoichiometry, solid phase compositions, and vapor losses due to oxidation-volatilization. Simple criteria are postulated which can aid the experimentalist in selecting the proper gas mixture for oxide--metal eutectic composite growth. The Cr 2 O 3 --Mo--Cr systems was used to verify certain aspects of the proposed criteria

  11. Development of a simultaneous partial nitrification and anaerobic ammonia oxidation process in a single reactor.

    Science.gov (United States)

    Cho, Sunja; Fujii, Naoki; Lee, Taeho; Okabe, Satoshi

    2011-01-01

    Up-flow oxygen-controlled biofilm reactors equipped with a non-woven fabric support were used as a single reactor system for autotrophic nitrogen removal based on a combined partial nitrification and anaerobic ammonium oxidation (anammox) reaction. The up-flow biofilm reactors were initiated as either a partial nitrifying reactor or an anammox reactor, respectively, and simultaneous partial nitrification and anammox was established by careful control of the aeration rate. The combined partial nitrification and anammox reaction was successfully developed in both biofilm reactors without additional biomass inoculation. The reactor initiated as the anammox reactor gave a slightly higher and more stable mean nitrogen removal rate of 0.35 (±0.19) kg-N m(-3) d(-1) than the reactor initiated as the partial nitrifying reactor (0.23 (±0.16) kg-N m(-3) d(-1)). FISH analysis revealed that the biofilm in the reactor started as the anammox reactor were composed of anammox bacteria located in inner anoxic layers that were surrounded by surface aerobic AOB layers, whereas AOB and anammox bacteria were mixed without a distinguishable niche in the biofilm in the reactor started as the partial nitrifying reactor. However, it was difficult to efficiently maintain the stable partial nitrification owing to inefficient aeration in the reactor, which is a key to development of the combined partial nitrification and anammox reaction in a single biofilm reactor. Copyright © 2010 Elsevier Ltd. All rights reserved.

  12. Biological degradation of partially oxidated constituents of stabilized sapropel; Biologischer Abbau teiloxidierter Inhaltsstoffe stabilisierter Faulschlaemme

    Energy Technology Data Exchange (ETDEWEB)

    Scheminski, A.; Krull, R.; Hempel, D.C. [Technische Univ. Braunschweig (Germany). Inst. fuer Bioverfahrenstechnik

    1999-07-01

    Partial oxidation of sapropel with ozone destroys the cell walls of microorganisms in sludge and releases the cell constituents. Substances that are not biologically degraded because of the size or structure of their molecules are transformed into smaller, water-soluble and biologically degradable fractions by the reaction with ozone. The experiments aim to render the partially oxidated sewage sludge constituents highly biologically degradable using a minimum of oxidation agents. For the experiments described, stabilized sapropels with low biological activity are used. Hence the ozone is mainly used for the partial oxidation of recalcitrant constituents. (orig.) [German] Durch partielle Oxidation von Faulschlaemmen mit Ozon werden die Zellwaende der Mikroorganismen im Schlamm zerstoert und die Zellinhaltsstoffe freigesetzt. Dabei werden Substanzen, die aufgrund ihrer Molekuelgroesse oder -struktur biologisch nicht abgebaut werden, durch die Reaktion mit Ozon in kleinere, wasserloesliche und biologisch abbaubare Bruchstuecke ueberfuehrt. Ziel der Versuche ist es, durch den Einsatz moeglichst geringer Mengen an Oxidationsmitteln eine hohe biologische Abbaubarkeit der teiloxidierten Klaerschlamminhaltsstoffe zu erreichen. Fuer die hier vorgestellten Experimente wurden stabilisierte Faulschlaemme mit geringer biologischer Aktivitaet eingesetzt. Dadurch wird das Ozon vorwiegend zur Teiloxidation recalcitranter Inhaltsstoffe genutzt. (orig.)

  13. One-Pot Synthesis of Cu(II Complex with Partially Oxidized TTF Moieties

    Directory of Open Access Journals (Sweden)

    Hiroki Oshio

    2012-07-01

    Full Text Available The one-pot synthesis of a Cu(II complex with partially oxidized tetrathiafulvalene (TTF moieties in its capping MT-Hsae-TTF ligands, [CuII(MT-sae-TTF2] [CuICl2] was realized by the simultaneous occurrence of Cu(II complexation and CuIICl2 mediated oxidation of TTF moieties. The crystal structure was composed of one-dimensional columns formed by partially oxidized TTF moieties and thus the cation radical salt showed relatively high electrical conductivity. Tight binding band structure calculations indicated the existence of a Peierls gap due to the tetramerization of the TTF moieties in the one-dimensional stacking column at room temperature, which is consistent with the semiconducting behavior of this salt.

  14. Impact of partial fuel switch on household air pollutants in sub-Sahara Africa

    International Nuclear Information System (INIS)

    Tumwesige, Vianney; Okello, Gabriel; Semple, Sean; Smith, Jo

    2017-01-01

    Over 700 million people in Sub-Saharan Africa depend on solid biomass fuel and use simple cookstoves in poorly ventilated kitchens, which results in high indoor concentrations of household air pollutants. Switching from biomass to biogas as a cooking fuel can reduce airborne emissions of fine particulate matter (PM 2.5 ) and carbon monoxide (CO), but households often only partially convert to biogas, continuing to use solid biomass fuels for part of their daily cooking needs. There is little evidence of the benefits of partial switching to biogas. This study monitored real-time PM 2.5 and CO concentrations in 35 households in Cameroon and Uganda where biogas and firewood (or charcoal) were used. The 24 h mean PM 2.5 concentrations in households that used: (1) firewood and charcoal; (2) both firewood (mean 54% cooking time) and biogas (mean 46% cooking time); and (3) only biogas, were 449 μg m −3 , 173 μg m −3 and 18 μg m −3 respectively. The corresponding 24 h mean CO concentrations were 14.2 ppm, 2.7 ppm and 0.5 ppm. Concentrations of both PM 2.5 and CO were high and exceeded the World Health Organisation guidelines when firewood and charcoal were used. Partially switching to biogas reduced CO exposure to below the World Health Organisation guidelines, but PM 2.5 concentrations were only below the 24 h recommended limits when households fully converted to biogas fuel. These results indicate that partial switching from solid fuels to biogas is not sufficient and continues to produce concentrations of household air pollution that are likely to harm the health of those exposed. Programmes introducing biogas should aim to ensure that household energy needs can be fully achieved using biogas with no requirement to continue using solid fuels. - Highlights: • Air pollution exceeds WHO limits in African households using solid biomass fuels. • A partial switch to biogas reduced CO concentrations to below the WHO limit. • Particulates only fall to

  15. Total free radical species and oxidation equivalent in polluted air.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Tian, Haoqi; Liu, Yanrong; Chen, Xuefu; Li, Lan; Zhang, Yuanhang; Shi, Gaofeng

    2017-12-31

    Free radicals are the most important chemical intermediate or agent of the atmosphere and influenced by thousands of reactants. The free radicals determine the oxidizing power of the polluted air. Various gases present in smog or haze are oxidants and induce organ and cellular damage via generation of free radical species. At present, however, the high variability of total free radicals in polluted air has prevented the detection of possible trends or distributions in the concentration of those species. The total free radicals are a kind of contaminants with colorless, tasteless characteristics, and almost imperceptible by human body. Here we present total free radical detection and distribution characteristics, and analyze the effects of total free radicals in polluted air on human health. We find that the total free radical values can be described by not only a linear dependence on ozone at higher temperature period, but also a linear delay dependence on particulate matter at lower temperature period throughout the measurement period. The total free radical species distribution is decrease from west to east in Lanzhou, which closely related to the distribution of the air pollutants. The total free radical oxidation capacity in polluted air roughly matches the effects of tobacco smoke produced by the incomplete combustion of a controlled amount of tobacco in a smoke chamber. A relatively unsophisticated chromatographic fingerprint similarity is used for indicating preliminarily the effect of total free radicals in polluted air on human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Dosimetric effects of an air cavity for the SAVI partial breast irradiation applicator

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Susan L.; Pino, Ramiro [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States); Department of Radiation Oncology, Methodist Hospital, Houston, Texas 77030 and Texas Cancer Clinic, San Antonio, Texas 78240 (United States)

    2010-08-15

    Purpose: To investigate the dosimetric effect of the air inside the SAVI partial breast irradiation device. Methods: The authors have investigated how the air inside the SAVI partial breast irradiation device changes the delivered dose from the homogeneously calculated dose. Measurements were made with the device filled with air and water to allow comparison to a homogenous dose calculation done by the treatment planning system. Measurements were made with an ion chamber, TLDs, and film. Monte Carlo (MC) simulations of the experiment were done using the EGSnrc suite. The MC model was validated by comparing the water-filled calculations to those from a commercial treatment planning system. Results: The magnitude of the dosimetric effect depends on the size of the cavity, the arrangement of sources, and the relative dwell times. For a simple case using only the central catheter of the largest device, MC results indicate that the dose at the prescription point 1 cm away from the air-water boundary is about 9% higher than the homogeneous calculation. Independent measurements in a water phantom with a similar air cavity gave comparable results. MC simulation of a realistic multidwell position plan showed discrepancies of about 5% on average at the prescription point for the largest device. Conclusions: The dosimetric effect of the air cavity is in the range of 3%-9%. Unless a heterogeneous dose calculation algorithm is used, users should be aware of the possibility of small treatment planning dose errors for this device and make modifications to the treatment delivery, if necessary.

  17. Partial pit exhaust improves indoor air quality and effectiveness of air cleaning in livestock housing

    DEFF Research Database (Denmark)

    Zhang, Guoqiang; Bjerg, B.; Zong, C.

    2017-01-01

    Ammonia and odor emissions from livestock production systems cause negative impact on atmospheric environment and local society. It is, therefore, important to develop cost-effective methods to reduce these emissions. Air cleaning technologies, including chemical and biological filters, have been...... and experimental investigations, to identify important factors that may affect the system performances for removal of ammonia and other pollutants from the animal housing and to address the extension work that may be needed to apply the method in actual production scales. It is shown that PPAE is an effective...

  18. Oxidation of SiC/BN/SiC Composites in Reduced Oxygen Partial Pressures

    Science.gov (United States)

    Opila, Elizabeth J.; Boyd, Meredith

    2010-01-01

    SiC fiber-reinforced SiC composites with a BN interphase are proposed for use as leading edge structures of hypersonic vehicles. The durability of these materials under hypersonic flight conditions is therefore of interest. Thermogravimetric analysis was used to characterize the oxidation kinetics of both the constituent fibers and composite coupons at four temperatures: 816, 1149, 1343, and 1538 C (1500, 2100, 2450, and 2800 F) and in oxygen partial pressures between 5% and 0.1% (balance argon) at 1 atm total pressure. One edge of the coupons was ground off so the effects of oxygen ingress into the composite could be monitored by post-test SEM and EDS. Additional characterization of the oxidation products was conducted by XPS and TOF-SIMS. Under most conditions, the BN oxidized rapidly, leading to the formation of borosilicate glass. Rapid initial oxidation followed by volatilization of boria lead to protective oxide formation and further oxidation was slow. At 1538C in 5% oxygen, both the fibers and coupons exhibited borosilicate glass formation and bubbling. At 1538C in 0.1% oxygen, active oxidation of both the fibers and the composites was observed leading to rapid SiC degradation. BN oxidation at 1538C in 0.1% oxygen was not significant.

  19. Quantifying effects of oxidant air pollutants on agricultural crops

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, W H; Moskowitz, P D

    1983-01-01

    Estimating risks of air pollution damage to agricultural crops requires identifying crop location and size, likely doses, models for translating dose to response, and measures of response appropriate for economic analysis. Assessment of risk requires compatible data sets for each of these variables. Analysis of air pollution mixtures suggests that oxidant crop damage is caused by three compounds: ozone, nitrogen oxides, and peroxyacetylnitrates. The phytotoxicity of ozone, the most prevalent photochemical oxidant, has been studied more extensively than the other two oxidants, and its effects on vegetation are best understood. Response of vegetation to air pollutants was first characterized by foliar or visible injury. Subsequent research indicated that foliar injury did not translate directly into reduced plant growth or yield, which can be measured. Response to air pollutants may be influenced by physical, biological, and environmental factors. Inherent genetic resistance is probably the most important single factor affecting plant response, although environmental factors influencing stomatal aperture may also be important. For several crops open-top chamber studies and cross sectional analyses of field data provide adequate information to develop dose-response functions. All of these studies have both strengths and weaknesses. Although a number of different models exist for selected crops, there is no single biological or statistical criterion which identifies the best or most accurate model.

  20. Partial oxidation of n- and i-pentane over promoted vanadium-phosphorus oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zazhigalov, V.A.; Mikhajluk, B.D.; Komashko, G.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    It is known, that the cost of raw materials for catalytic oxidation processes is about 60% of the product price. Cheap initial compounds to produce variety of products and to replace olefins and aromatic hydrocarbons are paraffins. That is why catalytic systems which could be possibly rather efficient in selective oxidation of paraffin hydrocarbons are under very close investigation now. One of such processes in n-pentane oxidation. The obtained results on n-pentane oxidation over VPO catalysts were quite encouraging in respect of possible reach high selectivity and yield of phthalic anhydride. However, in our work it was shown that the main product of n-pentane oxidation in the presence of VPO catalytic system as well as VPMeO was maleic anhydride. Some later our results were confirmed in, where to grow the selectivity towards phthalic anhydride the Co-additive was introduced. On the basis of the proposal made before on the mechanism of paraffins conversion over the vanadyl pyrophosphate surface with their activation at the first and fourth carbon atoms, we assumed possible methylmaleic (citraconic) anhydride forming at n- and i-pentane oxidation. This assumption has been recently supported by both our and other researchers` experimental results. In it was also hypothized possible mechanistic features for phthalic anhydride forming from n-pentane. The present work deals with the results of n- and i-pentane oxidation over VPO catalysts promoted with Bi, Cs, Te, Zr. (orig.)

  1. Oxidative desulfurization of diesel with TBHP/isobutyl aldehyde/air oxidation system

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei; Wang, Chengyong; Lin, Peng; Lu, Xiaoping [Institute of Sonochemical Engineering, Nanjing University of Technology, Nanjing 210009, Jiangsu (China)

    2011-01-15

    Oxidative desulfurization of hydrogenation diesel (40 mL) was studied using air as oxidant, tert-butyl hydroperoxide (TBHP) as radical initiator at ambient pressure and moderate temperature in the presence of isobutyl aldehyde. TBHP could accelerate the production of carbonyl radical and its peroxidation. When the molar fraction of TBHP was 5 mmol, the conversion of DBT could reach 96.1% in the present of 20 mmol isobutyl aldehyde and air, which was more than that of 85.5% without initiator. The air was an effective oxidant and acetonitrile was an optimal solvent in this process. The sulfur content of the hydrogenation diesel could be reduced from 403 to 13 ppm (96.8% removed) under the synergistic effect of air, TBHP and isobutyl aldehyde. (author)

  2. Conversion and Estrogenicity of 17β-estradiol During Photolytic/Photocatalytic Oxidation and Catalytic Wet-air Oxidation.

    Science.gov (United States)

    Bistan, Mirjana; Tišler, Tatjana; Pintar, Albin

    2012-06-01

    Estrogen 17β-estradiol (E2), produced by human body and excreted into municipal wastewaters, belongs to the group of endocrine disrupting compounds that are resistant to biological degradation. The aim of this study was to assess the efficiency of E2 removal from aqueous solutions by means of catalytic wet-air oxidation (CWAO) and photolytic/photocatalytic oxidation. CWAO experiments were conducted in a trickle-bed reactor at temperatures up to 230 °C and oxygen partial pressure of 10 bar over TiO2 and Ru/TiO2 solids. Photolytic/photocatalytic oxidation was carried out in a batch slurry reactor employing a TiO2 P-25 (Degussa) catalyst under visible or UV light. HPLC analysis and yeast estrogen screen assay were used to evaluate the removal of E2 and estrogenicity of treated samples. The latter was completely removed during photolytic/photocatalytic oxidation under UV (365 nm) light and photocatalytic oxidation under visible light. In CWAO experiments, complete removal of both E2 and estrogenicity from the feed solution were noticed in the presence of TiO2 and Ru/TiO2 catalysts.

  3. Models for the Configuration and Integrity of Partially Oxidized Fuel Rod Cladding at High Temperatures

    International Nuclear Information System (INIS)

    Siefken, L.J.

    1999-01-01

    Models were designed to resolve deficiencies in the SCDAP/RELAP5/MOD3.2 calculations of the configuration and integrity of hot, partially oxidized cladding. These models are expected to improve the calculations of several important aspects of fuel rod behavior. First, an improved mapping was established from a compilation of PIE results from severe fuel damage tests of the configuration of melted metallic cladding that is retained by an oxide layer. The improved mapping accounts for the relocation of melted cladding in the circumferential direction. Then, rules based on PIE results were established for calculating the effect of cladding that has relocated from above on the oxidation and integrity of the lower intact cladding upon which it solidifies. Next, three different methods were identified for calculating the extent of dissolution of the oxidic part of the cladding due to its contact with the metallic part. The extent of dissolution effects the stress and thus the integrity of the oxidic part of the cladding. Then, an empirical equation was presented for calculating the stress in the oxidic part of the cladding and evaluating its integrity based on this calculated stress. This empirical equation replaces the current criterion for loss of integrity which is based on temperature and extent of oxidation. Finally, a new rule based on theoretical and experimental results was established for identifying the regions of a fuel rod with oxidation of both the inside and outside surfaces of the cladding. The implementation of these models is expected to eliminate the tendency of the SCDAP/RELAP5 code to overpredict the extent of oxidation of the upper part of fuel rods and to underpredict the extent of oxidation of the lower part of fuel rods and the part with a high concentration of relocated material. This report is a revision and reissue of the report entitled, Improvements in Modeling of Cladding Oxidation and Meltdown

  4. Partial oxidation of methane over Ni/Mg/Al/La mixed oxides prepared from layered double hydrotalcites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [Low Carbon Energy Conversion Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201203 (China); State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Ning; Wei, Wei [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi (China); Sun, Yuhan [Low Carbon Energy Conversion Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201203 (China); State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi (China)

    2010-11-15

    A series of Ni/Mg/Al/La mixed oxides prepared by thermal decomposition of layered double hydrotalcites (HT) were characterized by XRD, ICP, EXAFS, TGA, TPR-H{sub 2}, SEM, and N{sub 2} adsorption/desorption technique. The results revealed the formation of periclase-type catalysts with mesoporous structure, and the addition of La{sup 3+} lowered the phase crystallization with the formation of small oxide particles. Such catalysts had both high activities and stabilities toward partial oxidation of methane (POM). The catalyst containing 6.5 mol.% La{sup 3+} showed the highest performance at 1053 K with CH{sub 4} conversion of 99%, CO selectivity of 93% and H{sub 2} selectivity of 96%, which could be attributed to the presence of highly dispersed nickel and then the resistance to coke formation due to the promotion effect of lanthanum. (author)

  5. Interim results from UO2 fuel oxidation tests in air

    International Nuclear Information System (INIS)

    Campbell, T.K.; Gilbert, E.R.; Thornhill, C.K.; White, G.D.; Piepel, G.F.; Griffin, C.W.j.

    1987-08-01

    An experimental program is being conducted at Pacific Northwest Laboratory (PNL) to extend the characterization of spent fuel oxidation in air. To characterize oxidation behavior of irradiated UO 2 , fuel oxidation tests were performed on declad light-water reactor spent fuel and nonirradited UO 2 pellets in the temperature range of 135 to 250 0 C. These tests were designed to determine the important independent variables that might affect spent fuel oxidation behavior. The data from this program, when combined with the test results from other programs, will be used to develop recommended spent fuel dry-storage temperature limits in air. This report describes interim test results. The initial PNL investigations of nonirradiated and spent fuels identified the important testing variables as temperature, fuel burnup, radiolysis of the air, fuel microstructure, and moisture in the air. Based on these initial results, a more extensive statistically designed test matrix was developed to study the effects of temperature, burnup, and moisture on the oxidation behavior of spent fuel. Oxidation tests were initiated using both boiling-water reactor and pressurized-water reactor fuels from several different reactors with burnups from 8 to 34 GWd/MTU. A 10 5 R/h gamma field was applied to the test ovens to simulate dry storage cask conditions. Nonirradiated fuel was included as a control. This report describes experimental results from the initial tests on both the spent and nonirradiated fuels and results to date on the tests in a 10 5 R/h gamma field. 33 refs., 51 figs., 6 tabs

  6. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    Science.gov (United States)

    Sundararaman, Ramanathan

    Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

  7. High Temperature Oxidation Behavior of Zirconium Alloy with Nano structured Oxide Layer in Air Environment

    International Nuclear Information System (INIS)

    Park, Y. J.; Kim, J. W.; Park, J. W.; Cho, S. O.

    2016-01-01

    If the temperature of the cladding materials increases above 1000 .deg. C, which can be caused by a loss of coolant accident (LOCA), Zr becomes an auto-oxidation catalyst and hence produces a huge amount of hydrogen gas from water. Therefore, many investigations are being carried out to prevent (or reduce) the hydrogen production from Zr-based cladding materials in the nuclear reactors. Our team has developed an anodization technique by which nanostructured oxide can be formed on various flat metallic elements such as Al, Ti, and Zr-based alloy. Anodization is a simple electrochemical technique and requires only a power supply and an electrolyte. In this study, Zr-based alloys with nanostructured oxide layers were oxidized by using Thermogravimetry analysis (TGA) and compared with the pristine one. It reveals that the nanostructured oxide layer can prevent oxidation of substrate metal in air. Oxidation behavior of the pristine Zr-Nb-Sn alloy and the Zr-Nb-Sn alloy with nanostructured oxide layer evaluated by measuring weight gain (TGA). In comparison with the pristine Zr-Nb-Sn alloy, weight gain of the Zr-Nb-Sn alloy with nanostructured oxide layer is lower than 10% even for 12 hours oxidation in air.

  8. Hydrogen Production via Synthetic Gas by Biomass/Oil Partial Oxidation

    Czech Academy of Sciences Publication Activity Database

    Hanika, Jiří; Lederer, J.; Tukač, V.; Veselý, Václav; Kováč, D.

    176-177, - (2011), s. 286-290 ISSN 1385-8947. [International Conference on Chemical Reactors CHEMREACTOR-19 /19./. Vienna, 05.09.2010-09.09.2010] R&D Projects: GA MPO 2A-2TP1/024 Institutional research plan: CEZ:AV0Z40720504 Keywords : hydrogen * biomass * partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.461, year: 2011

  9. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    XUJian; WEIWeisheng; 等

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  10. Visualizing a Catalyst at Work during the Ignition of the Catalytic Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Kimmerle, Bertram; Grunwaldt, Jan-Dierk; Baiker, Alfons

    2009-01-01

    We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which...... in combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide....

  11. Kinetic studies of isooctane partial oxidation over a nickel-based catalyst

    International Nuclear Information System (INIS)

    Ibrahim, Hussameldin; Idem, Raphael; Aboudheir, Ahmed

    2006-01-01

    The production of hydrogen (H 2 ) for fuel cell applications in mobile vehicles by reforming technologies such as partial oxidation of various fossil fuels has gained much attention recently. In this study, the production of H 2 by the catalytic partial oxidation of isooctane ((C 8 H 18 ) used here as a surrogate for gasoline) was investigated over alumina (AI 2 O 3 )supported nickel (Ni) catalyst. The work investigated the kinetics of the partial oxidation of isooctane over a stable Ni/□-AI 2 O 3 catalyst in the range of 863 to 913 K, at atmospheric pressure, W/F i c8 in the range of 1.97 to 8.58 g h mol - 1, and molar feed ratio in the range of 2.0 to 8.0 experiments to obtain kinetic data were performed in a 12.7 mm diameter Inconel micro-reactor housed in an electrically controlled furnace. The chemical reaction was then modeled using rate models developed from the Langmuir-Hinshelwood-hougen-Watson (LHHW) and Eley-Rideal (ER) formulations. The model parameters were estimated using an adaptive Gauss-Newton and Marquardi-Levenberg minimization algorithm. Rival models were screened for their thermodynamic consistency and physicochemical significance of estimated parameters. Langmuir-Hinshelwood-hougen-Watson mechanism requiring the dissociative adsorption of isooctane and oxygen on two different sites appeared to be the most likely pathway for the partial oxidation reaction of isooctane. Reaction order with respect to isooctane indicates the strong coverage of nickel by isooctane. The activation energy of 73±3.1 kJ mol - 1 estimated from the LHHW model is consistent with the trend observed with lower hydrocarbons.(Author)

  12. Air-oxidized linalyl acetate - an emerging fragrance allergen?

    Science.gov (United States)

    Hagvall, Lina; Berglund, Victoria; Bråred Christensson, Johanna

    2015-04-01

    Linalyl acetate is a fragrance chemical that is prone to autoxidation. Exposure to linalyl acetate occurs through cosmetic products and essential oils, but is difficult to assess, as linalyl acetate is not labelled in the EU. To investigate the frequencies of contact allergy to oxidized linalyl acetate among dermatitis patients, and to investigate the autoxidation of linalyl acetate in terms of hydroperoxide formation and sensitization potency. Hydroperoxide formation in air-exposed linalyl acetate was determined with high-performance liquid chromatography. The sensitization potencies of hydroperoxides were determined with the local lymph node assay. One thousand seven hundred and seventeen patients were patch tested with oxidized linalyl acetate at 6.0% in petrolatum. Of the patients, 2.2% showed positive reactions to oxidized linalyl acetate. Forty-three per cent of the positive patients also had positive patch test reactions to other fragrance markers. Linalyl acetate hydroperoxides were detected early in the autoxidation process, and accumulated to a concentration of 37% after 42 weeks of air exposure. The linalyl acetate hydroperoxides were classified as moderate sensitizers. The frequency of positive reactions to oxidized linalyl acetate is comparable to that of previously studied oxidized fragrance terpenes. Oxidized linalyl acetate could thus be a common fragrance contact allergen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Thermodynamic analysis and conceptual design for partial coal gasification air preheating coal-fired combined cycle

    Science.gov (United States)

    Xu, Yue; Wu, Yining; Deng, Shimin; Wei, Shirang

    2004-02-01

    The partial coal gasification air pre-heating coal-fired combined cycle (PGACC) is a cleaning coal power system, which integrates the coal gasification technology, circulating fluidized bed technology, and combined cycle technology. It has high efficiency and simple construction, and is a new selection of the cleaning coal power systems. A thermodynamic analysis of the PGACC is carried out. The effects of coal gasifying rate, pre-heating air temperature, and coal gas temperature on the performances of the power system are studied. In order to repower the power plant rated 100 MW by using the PGACC, a conceptual design is suggested. The computational results show that the PGACC is feasible for modernizing the old steam power plants and building the new cleaning power plants.

  14. Complete and Partial Photo-oxidation of Dissolved Organic Matter Draining Permafrost Soils.

    Science.gov (United States)

    Ward, Collin P; Cory, Rose M

    2016-04-05

    Photochemical degradation of dissolved organic matter (DOM) to carbon dioxide (CO2) and partially oxidized compounds is an important component of the carbon cycle in the Arctic. Thawing permafrost soils will change the chemical composition of DOM exported to arctic surface waters, but the molecular controls on DOM photodegradation remain poorly understood, making it difficult to predict how inputs of thawing permafrost DOM may alter its photodegradation. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer of arctic soils to complete and partial photo-oxidation and investigated changes in the chemical composition of each DOM source following sunlight exposure. Permafrost and organic mat DOM had similar lability to photomineralization despite substantial differences in initial chemical composition. Concurrent losses of carboxyl moieties and shifts in chemical composition during photodegradation indicated that photodecarboxylation could account for 40-90% of DOM photomineralized to CO2. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic moieties with antioxidant properties. These results suggest that photodegradation will likely continue to be an important control on DOM fate in arctic freshwaters as the climate warms and permafrost soils thaw.

  15. Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water

    KAUST Repository

    Alshammari, Y.M.

    2015-01-01

    © 2014 The Institution of Chemical Engineers. This work reports the experimental analysis of partial oxidation of n-hexadecane under supercritical water conditions. A novel reactor flow system was developed which allows for total decomposition of hydrogen peroxide in a separate reactor followed partial oxidation of n-hexadecane in a gasification reactor instead of having both reactions in one reactor. The kinetics of hydrothermal decomposition of hydrogen peroxide was studied in order to confirm its full conversion into water and oxygen under the desired partial oxidation conditions, and the kinetic data were found in a good agreement with previously reported literature. The gas yield and gasification efficiency were investigated under different operating parameters. Furthermore, the profile of C-C/C=C ratio was studied which showed the favourable conditions for maximising yields of n-alkanes via hydrogenation of their corresponding 1-alkenes. Enhanced hydrogenation of 1-alkenes was observed at higher O/C ratios and higher residence times, shown by the increase in the C-C/C=C ratio to more than unity, while increasing the temperature has shown much less effect on the C-C/C=C ratio at the current experimental conditions. In addition, GC-MS analysis of liquid samples revealed the formation of heavy oxygenated compounds which may suggest a new addition reaction to account for their formation under the current experimental conditions. Results show new promising routes for hydrogen production with in situ hydrogenation of heavy hydrocarbons in a supercritical water reactor.

  16. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot

    Directory of Open Access Journals (Sweden)

    R. Prasad

    2011-01-01

    Full Text Available To comply with the stringent emission regulations on soot, diesel vehicles manufacturers more and more commonly use diesel particulate filters (DPF. These systems need to be regenerated periodically by burning soot that has been accumulated during the loading of the DPF. Design of the DPF requires rate of soot oxidation. This paper describes the kinetics of catalytic oxidation of diesel soot with air under isothermal conditions. Kinetics data were collected in a specially designed mini-semi-batch reactor. Under the high air flow rate assuming pseudo first order reaction the activation energy of soot oxidation was found to be, Ea = 160 kJ/ mol. ©2010 BCREC UNDIP. All rights reserved(Received: 14th June 2010, Revised: 18th July 2010, Accepted: 9th August 2010[How to Cite: R. Prasad, V.R. Bella. (2010. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot. Bulletin of Chemical Reaction Engineering and Catalysis, 5(2: 95-101. doi:10.9767/bcrec.5.2.796.95-101][DOI:http://dx.doi.org/10.9767/bcrec.5.2.796.95-101 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/796]Cited by in: ACS 1 |

  17. Partial oxidation of landfill leachate in supercritical water: Optimization by response surface methodology

    International Nuclear Information System (INIS)

    Gong, Yanmeng; Wang, Shuzhong; Xu, Haidong; Guo, Yang; Tang, Xingying

    2015-01-01

    Highlights: • Partial oxidation of landfill leachate in supercritical water was investigated. • The process was optimized by Box–Behnken design and response surface methodology. • GY H2 , TRE and CR could exhibit up to 14.32 mmol·gTOC −1 , 82.54% and 94.56%. • Small amounts of oxidant can decrease the generation of tar and char. - Abstract: To achieve the maximum H 2 yield (GY H2 ), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GY H2 , CR and TRE were established with Box–Behnken design. GY H2 , CR and TRE reached up to 14.32 mmol·gTOC −1 , 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO 2 and H 2 were the most abundant gaseous products. As a product of nitrogen-containing organics, NH 3 has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient

  18. Oxidation of urate by a therapeutic nitric oxide/air mixture

    International Nuclear Information System (INIS)

    Hicks, M.; Nguyen, L.; Day, R.; Rogers, P.

    1996-01-01

    Full text: Little is known about the potential toxicological consequences of therapeutic exposure of lung tissue to inhaled nitric oxide (NO). This route of administration is currently being successfully employed for the treatment of pulmonary hypertension and other lung pathologies including acute reperfusion injury in lung transplant patients. The toxicity of NO lies in its ability to act as an oxidant either in its own right or in concert with oxygen or with the superoxide free radical. One important interaction may be the reaction of these products with protective antioxidants in the lung epithelial lining fluid. One such antioxidant found in significant concentrations in both upper and lower airways is uric acid. In the present study, urate solutions (30μM) were exposed to a therapeutic concentration of NO gas, (35 ppm in air), for up to 90 minutes. Oxidative changes were followed spectrophotometrically and by HPLC. Significant loss of uric acid was observed with a concomitant formation of nitrite and allantoin, the stable oxidation product of NO and the major oxidation product of uric acid, respectively. No oxidation of urate was observed in the presence of air alone or when urate was incubated with nitrite. Uric acid oxidation could also be prevented by passing the NO / air stream through 10% KOH before the uric acid solution. This strategy removed trace amounts of higher oxides of nitrogen, (especially NO 2 ), from the NO / air stream. Thus, therapeutic inhalation of NO may deplete soluble antioxidants such as uric acid, especially during long-term chronic exposure unless care is taken to minimise formation of higher oxides of nitrogen

  19. 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.

  20. Thermodynamic and kinetic aspects of UO 2 fuel oxidation in air at 400-2000 K

    Science.gov (United States)

    Taylor, Peter

    2005-09-01

    Most nuclear fuel oxidation research has addressed either low-temperature (1500 K) steam oxidation linked to reactor safety. This paper attempts to unify modelling for air oxidation of UO 2 fuel over a wide range of temperature, and thus to assist future improvement of the ASTEC code, co-developed by IRSN and GRS. Phenomenological correlations for different temperature ranges distinguish between oxidation on the scale of individual grains to U 3O 7 and U 3O 8 below ˜700 K and individual fragments to U 3O 8 via UO 2+ x and/or U 4O 9 above ˜1200 K. Between about 700 and 1200 K, empirical oxidation rates slowly decline as the U 3O 8 product becomes coarser-grained and more coherent, and fragment-scale processes become important. A more mechanistic approach to high-temperature oxidation addresses questions of oxygen supply, surface reaction kinetics, thermodynamic properties, and solid-state oxygen diffusion. Experimental data are scarce, however, especially at low oxygen partial pressures and high temperatures.

  1. Oxidation behavior of V-Cr-Ti alloys in low-partial-pressure oxygen environments

    International Nuclear Information System (INIS)

    Natesan, K.; Uz, M.

    1998-01-01

    A test program is in progress at Argonne National Laboratory to evaluate the effect of pO 2 in the exposure environment on oxygen uptake, scaling kinetics, and scale microstructure in V-Cr-Ti alloys. The data indicate that the oxidation process follows parabolic kinetics in all of the environments used in the present study. From the weight change data, parabolic rate constants were evaluated as a function of temperature and exposure environment. The temperature dependence of the parabolic rate constants was described by an Arrhenius relationship. Activation energy for the oxidation process was fairly constant in the oxygen pressure range of 1 x 10 -6 to 1 x 10 -1 torr for both the alloys. The activation energy for oxidation in air was significantly lower than in low-pO 2 environments, and for oxidation in pure O 2 at 760 torr was much lower than in low-pO 2 environments. X-ray diffraction analysis of the specimens showed that VO 2 was the dominant phase in low-pO 2 environments, while V 2 O 5 was dominant in air and in pure oxygen at 76f0 torr

  2. A novel technique for hydrogen production from hog-manure in supercritical partial oxidation (SCWPO)

    Energy Technology Data Exchange (ETDEWEB)

    Youssef, Emhemmed A.; Charpentier, Paul [Western Ontario Univ., London, ON (Canada). Dept. of Chemical and Biochemical Engineering; Nakhla, George [Western Ontario Univ., London, ON (Canada). Dept. of Chemical and Biochemical Engineering; Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering; Elbeshbishy, Elsayed; Hafez, Hisham [Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering

    2010-07-01

    In this study, the catalytic hydrogen production from hog manure using supercritical water partial oxidation was investigated in a batch reactor at a temperature of 500 C, and pressure of 28 MPa using several metallic catalysts. Hog manure was characterized by a total and soluble chemical oxygen demand (TCOD, SCOD) of 57000 and 28000 mg/L, total and volatile suspended solids (TSS, VSS) of 25000, 19000, and ammonia of 2400 mg/L, respectively. The order of H{sub 2} production was the following: Pd/AC > Ru/Al{sub 2}O{sub 3} > Ru/AC > AC > NaOH. The order of COD reduction efficiency was as follows: NaOH > Ru/AC > AC > Ru/Al{sub 2}O{sub 3} > Pd/AC. The behaviour of the volatile fatty acids (VFA's), ethanol, methanol, ammonia, H{sub 2}S, and Sulfate was investigated experimentally and discussed. A 35 % reduction in the H{sub 2} and CH{sub 4} yields was observed in the sequential gasification partial oxidation (oxidant at an 80 % of theoretical requirement) experiments compared to the gasification experiments (catalyst only). Moreover, this reduction in gas yields was coincided with a 45 % reduction in the liquid effluent chemical oxygen demand (COD), 60 % reduction of the ammonia concentration in the liquid effluent, and 20 % reduction in the H{sub 2}S concentration in the effluent gas. (orig.)

  3. The influence of moisture on air oxidation of UO2: Calculations and observations

    International Nuclear Information System (INIS)

    Taylor, P.; Lemire, R.J.; Wood, D.D.

    1993-01-01

    Phase relationships among solids in the UO 2 -O 2 -H 2 O system at 25, 100, and 200C and pressures to 2 MPa have been calculated from critically evaluated thermodynamic data. Stability limits of the solids are expressed in terms of oxygen and water partial pressures at each temperature. The results are then discussed in terms of known UO 2 oxidation reactions and uranium mineralogy. Particular attention is paid to UO 3 hydrates, some of which are shown to be stable phases in air at very low relative humidities (down to ∼0.1% at 25C). This is relevant to fuel storage because of the very high molar volumes of these phases, relative to UO 2 , and consequent potential for damage to defected fuel assemblies. Comparison of the calculated phase relationships with observed UO 2 oxidation behavior helps to identify those phase interconversions that are kinetically constrained

  4. Reduced graphene oxide for Li–air batteries

    DEFF Research Database (Denmark)

    Storm, Mie Møller; Overgaard, Marc; Younesi, Reza

    2015-01-01

    Reduced graphene oxide (rGO) has shown great promise as an air-cathode for Li-air batteries with high capacity. In this article we demonstrate how the oxidation time of graphene oxide (GO) affects the ratio of different functional groups and how trends of these in GO are extended to chemically...... and thermally reduced GO. We investigate how differences in functional groups and synthesis may affect the performance of Li-O-2 batteries. The oxidation timescale of the GO was varied between 30 min and 3 days before reduction. Powder Xray diffraction, micro-Raman, FE-SEM, BET analysis, and XPS were used...... techniques can enhance the structural understanding of rGO. Different rGO cathodes were tested in Li-O-2 batteries which revealed a difference in overpotentials and discharge capacities for the different rGO's. We report the highest Li-O-2 battery discharge capacity recorded of approximately 60,000 m...

  5. Impact of partial fuel switch on household air pollutants in sub-Sahara Africa.

    Science.gov (United States)

    Tumwesige, Vianney; Okello, Gabriel; Semple, Sean; Smith, Jo

    2017-12-01

    Over 700 million people in Sub-Saharan Africa depend on solid biomass fuel and use simple cookstoves in poorly ventilated kitchens, which results in high indoor concentrations of household air pollutants. Switching from biomass to biogas as a cooking fuel can reduce airborne emissions of fine particulate matter (PM 2.5 ) and carbon monoxide (CO), but households often only partially convert to biogas, continuing to use solid biomass fuels for part of their daily cooking needs. There is little evidence of the benefits of partial switching to biogas. This study monitored real-time PM 2.5 and CO concentrations in 35 households in Cameroon and Uganda where biogas and firewood (or charcoal) were used. The 24 h mean PM 2.5 concentrations in households that used: (1) firewood and charcoal; (2) both firewood (mean 54% cooking time) and biogas (mean 46% cooking time); and (3) only biogas, were 449 μg m -3 , 173 μg m -3 and 18 μg m -3 respectively. The corresponding 24 h mean CO concentrations were 14.2 ppm, 2.7 ppm and 0.5 ppm. Concentrations of both PM 2.5 and CO were high and exceeded the World Health Organisation guidelines when firewood and charcoal were used. Partially switching to biogas reduced CO exposure to below the World Health Organisation guidelines, but PM 2.5 concentrations were only below the 24 h recommended limits when households fully converted to biogas fuel. These results indicate that partial switching from solid fuels to biogas is not sufficient and continues to produce concentrations of household air pollution that are likely to harm the health of those exposed. Programmes introducing biogas should aim to ensure that household energy needs can be fully achieved using biogas with no requirement to continue using solid fuels. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Partially oxidized atomic cobalt layers for carbon dioxide electroreduction to liquid fuel

    Science.gov (United States)

    Gao, Shan; Lin, Yue; Jiao, Xingchen; Sun, Yongfu; Luo, Qiquan; Zhang, Wenhua; Li, Dianqi; Yang, Jinlong; Xie, Yi

    2016-01-01

    Electroreduction of CO2 into useful fuels, especially if driven by renewable energy, represents a potentially ‘clean’ strategy for replacing fossil feedstocks and dealing with increasing CO2 emissions and their adverse effects on climate. The critical bottleneck lies in activating CO2 into the CO2•- radical anion or other intermediates that can be converted further, as the activation usually requires impractically high overpotentials. Recently, electrocatalysts based on oxide-derived metal nanostructures have been shown to enable CO2 reduction at low overpotentials. However, it remains unclear how the electrocatalytic activity of these metals is influenced by their native oxides, mainly because microstructural features such as interfaces and defects influence CO2 reduction activity yet are difficult to control. To evaluate the role of the two different catalytic sites, here we fabricate two kinds of four-atom-thick layers: pure cobalt metal, and co-existing domains of cobalt metal and cobalt oxide. Cobalt mainly produces formate (HCOO-) during CO2 electroreduction; we find that surface cobalt atoms of the atomically thin layers have higher intrinsic activity and selectivity towards formate production, at lower overpotentials, than do surface cobalt atoms on bulk samples. Partial oxidation of the atomic layers further increases their intrinsic activity, allowing us to realize stable current densities of about 10 milliamperes per square centimetre over 40 hours, with approximately 90 per cent formate selectivity at an overpotential of only 0.24 volts, which outperforms previously reported metal or metal oxide electrodes evaluated under comparable conditions. The correct morphology and oxidation state can thus transform a material from one considered nearly non-catalytic for the CO2 electroreduction reaction into an active catalyst. These findings point to new opportunities for manipulating and improving the CO2 electroreduction properties of metal systems

  7. Critical analysis of partial discharge dynamics in air filled spherical voids

    Science.gov (United States)

    Callender, G.; Golosnoy, I. O.; Rapisarda, P.; Lewin, P. L.

    2018-03-01

    In this paper partial discharge (PD) is investigated inside a spherical air filled void at atmospheric pressure using a drift diffusion model. Discharge dynamics consisted of an electron avalanche transitioning into positive streamer, in agreement with earlier work on dielectric barrier discharges. Different model configurations were utilised to test many of the concepts employed in semi-analytical PD activity models, which use simplistic descriptions of the discharge dynamics. The results showed that many of these concepts may be erroneous, with significant discrepancies between the canonical reasoning and the simulation results. For example, the residual electric field, the electric field after a discharge, is significantly lower than the estimates used by classical PD activity models in the literature.

  8. Effects of Oxygen Partial Pressure on Oxidation Behavior of CMnSi TRIP Steel in an Oxidation-Reduction Scheme

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong-Hwan; Huh, Joo-Youl [Korea University, Seoul (Korea, Republic of); Kim, Myung-Soo; Kim, Jong-Sang [POSCO Technical Research Laboratories, Gwangyang (Korea, Republic of)

    2017-02-15

    An oxidation-reduction scheme is an alternative approach for improving the galvanizability of advanced high-strength steel in the continuous hot-dip galvanizing process. Here, we investigated the effect of oxygen partial pressure (Po{sub 2}) on the oxidation behavior of a transformation-induced plasticity steel containing 1.5 wt% Si and 1.6 wt% Mn during heating to and holding for 60 s at 700 ℃ under atmospheres with various Po{sub 2} values. Irrespective of Po{sub 2}, a thin amorphous Si-rich layer of Si-Mn-O was formed underneath the Fe oxide scale (a Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} bilayer) in the heating stage. In contrast to Si, Mn tended to segregate at the scale surface as (Fe,Mn){sub 2}O{sub 3}. The multilayered structure of (Fe,Mn){sub 2}O{sub 3}/Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4}/amorphous Si-Mn-O remained even after extended oxidizing at 700 ℃ for 60 s. Fe{sub 2}O{sub 3} was the dominantly growing oxide phase in the scale. The enhanced growth rate of Fe{sub 2}O{sub 3} with increasing Po{sub 2} resulted in the formation of more Kirkendall voids in the amorphous Si-rich layer and a less Mn segregation at the scale surface. The mechanisms underlying the absence of FeO and the formation of Kirkendall voids are discussed.

  9. Partial oxidation of landfill leachate in supercritical water: Optimization by response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yanmeng; Wang, Shuzhong; Xu, Haidong; Guo, Yang; Tang, Xingying

    2015-09-15

    Highlights: • Partial oxidation of landfill leachate in supercritical water was investigated. • The process was optimized by Box–Behnken design and response surface methodology. • GY{sub H2}, TRE and CR could exhibit up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56%. • Small amounts of oxidant can decrease the generation of tar and char. - Abstract: To achieve the maximum H{sub 2} yield (GY{sub H2}), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GY{sub H2}, CR and TRE were established with Box–Behnken design. GY{sub H2}, CR and TRE reached up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO{sub 2} and H{sub 2} were the most abundant gaseous products. As a product of nitrogen-containing organics, NH{sub 3} has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient.

  10. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.

    Science.gov (United States)

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-04-03

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N 2 O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N 2 O model, which incorporated two N 2 O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH 2 OH) oxidation). The two-pathway model was used to describe N 2 O production from a granule-based partial nitritation (PN) reactor and provide insights into the N 2 O distribution inside granules. The model was evaluated by comparing simulation results with N 2 O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N 2 O dynamics and provided useful information about the shift of N 2 O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N 2 O production. The results further revealed a linear relationship between N 2 O production and ammonia oxidation rate (AOR) (R 2  = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N 2 O production by causing a change in AOR.

  11. Partial oxidation of municipal sludge with activited carbon catalyst in supercritical water

    International Nuclear Information System (INIS)

    Guo Yang; Wang Shuzhong; Gong Yanmeng; Xu Donghai; Tang Xingying; Ma Honghe

    2010-01-01

    The partial oxidation (POX) characteristics of municipal sludge in supercritical water (SCW) were investigated by using batch reactor. Effects of reaction parameters such as oxidant equivalent ratio (OER), reaction time and temperature were investigated. Activated carbon (AC) could effectively improve the mole fraction of H 2 in gas product at low OER. However, high OER (greater than 0.3) not only led to the combustion reaction of CO and H 2 , but also caused corrosion of reactor inner wall. Hydrogenation and polymerization of the intermediate products are possible reasons for the relative low COD removal rate in our tests. Metal oxide leached from the reactor inner wall and the main components of the granular sludge were deposited in the AC catalyst. Reaction time had more significant effect on BET surface area of AC than OER had. Long reaction time led to the methanation reaction following hydrolysis and oxidation reaction of AC in SCW in the presence of oxygen. Correspondingly, the possible reaction mechanisms were proposed.

  12. Catalysts Promoted with Niobium Oxide for Air Pollution Abatement

    Directory of Open Access Journals (Sweden)

    Wendi Xiang

    2017-05-01

    Full Text Available Pt-containing catalysts are currently used commercially to catalyze the conversion of carbon monoxide (CO and hydrocarbon (HC pollutants from stationary chemical and petroleum plants. It is well known that Pt-containing catalysts are expensive and have limited availability. The goal of this research is to find alternative and less expensive catalysts to replace Pt for these applications. This study found that niobium oxide (Nb2O5, as a carrier or support for certain transition metal oxides, promotes oxidation activity while maintaining stability, making them candidates as alternatives to Pt. The present work reports that the orthorhombic structure of niobium oxide (formed at 800 °C in air promotes Co3O4 toward the oxidation of both CO and propane, which are common pollutants in volatile organic compound (VOC applications. This was a surprising result since this structure of Nb2O5 has a very low surface area (about 2 m2/g relative to the more traditional Al2O3 support, with a surface area of 150 m2/g. The results reported demonstrate that 1% Co3O4/Nb2O5 has comparable fresh and aged catalytic activity to 1% Pt/γ-Al2O3 and 1% Pt/Nb2O5. Furthermore, 6% Co3O4/Nb2O5 outperforms 1% Pt/Al2O3 in both catalytic activity and thermal stability. These results suggest a strong interaction between niobium oxide and the active component—cobalt oxide—likely by inducing an oxygen defect structure with oxygen vacancies leading to enhanced activity toward the oxidation of CO and propane.

  13. Oxidation behaviour of U2Ti alloy in dry air

    International Nuclear Information System (INIS)

    Roy, S.P.; Gupta, N.K.; Jat, Ram Avtar; Parida, S.C.; Mukerjee, S.K.

    2016-01-01

    U 2 Ti alloy is being considered as promising storage material for storage of hydrogen isotopes. However, the absorption capacity of this reactive alloy can be affected due to presence of oxygen in the process gas. Hence, it is necessary to know the kinetic of this alloy in presence of oxygen. In this study, U 2 Ti alloy was prepared by arc melting method followed by vacuum annealing. The alloy was characterized by XRD, SEM and EDX methods. The isothermal oxidation behaviour of U 2 Ti alloy was investigated in the temperature range of 548-623 K in dry air for 24 hours by using thermo gravimetric technique. The oxidation curves are shown. The oxidation curves were analysed using the rate equation: (Δm/a) n = kt, where, (Δm/a) is the mass gain per unit area, n is the power exponent, k is the rate constant and t is time in (seconds). Analysis of the results shows that the oxidation reaction follows linear rate law (n ~ 1). Using the linear rate law, the rate constant (k) of oxidation reaction was evaluated at each temperature in the range 548-623 K. The variation of (ln k) with reciprocal temperature is shown. The activation energy of this oxidation reaction in the temperature range 548-623 K was calculated using the Arrhenius equation and found to be 76 kJ/mol. The XRD analysis of the oxidation products was found to be U 3 O 8 and TiO 2 . (author)

  14. Association of indoor air pollution with rhinitis symptoms, atopy and nitric oxide levels in exhaled air

    DEFF Research Database (Denmark)

    Hersoug, Lars-Georg; Husemoen, Lise Lotte N; Thomsen, Simon Francis

    2010-01-01

    Exposure to particulate matter (PM) outdoors can induce airway inflammation and exacerbation of asthma in adults. However, there is limited knowledge about the effects of exposure to indoor PM. The aim of this study was to investigate the association of exposure to indoor sources of PM...... with rhinitis symptoms, atopy and nitric oxide in exhaled air (FeNO) as a measure of airway inflammation....

  15. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

  16. Kinetics of catalyzed tritium oxidation in air at ambient temperature

    International Nuclear Information System (INIS)

    Sherwood, A.E.

    1980-01-01

    Tritium/air oxidation kinetic data are derived from measurements carried out with three catalysts. All experiments were carried out at room temperature - a regime that provides a severe test for catalyst effectiveness. Each catalyst consists of a high-surface-area substrate in pelletized form, onto which precious metal has been dispersed. The metal/substrate combinations investigated are: platinum/alumina, palladium/kaolin, and paladium/zeolite. Each of the dispersed-metal catalysts is extremely effective in promoting tritium oxidation in comparison with self-catalyzed atmospheric conversion; equivalent first-order rate constants are higher by roughly nine orders of magnitude. Electron-microprobe scans reveal that the dispersed metal is deposited near the outer surface of the catalyst, with metal concentration decreasing exponentially from the pellet surface. The platinum-based catalyst is more effective than the palladium catalysts on a surface-area basis by about a factor of three. Rate coefficients are determined from concentration decay following a spike injection of tritium into an air-filled enclosure processed by recirculation through an oxidation/adsorption system. The catalytic reaction is first-order in tritium concentration in the range 10 to 10 5 μCi/m 3 (4 ppt-40 ppB). Addition of hydrogen carrier gas is unnecessary. Catalytic activity for all three catalysts declines with time of exposure to air after activation, following a power-law decay with an exponent of -1/2. Reactivation with hot hydrogen gas effectively restores initial catalytic activity

  17. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

    Science.gov (United States)

    Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

  18. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Ojeda, Maria Eugenia [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain); Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Kim, Jungkwon [Chemical Engineering and Analytical Sciences Department, University of Manchester, Manchester (United Kingdom); Carrera, Julian [Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Metcalfe, Ian S. [Chemical Engineering and Advanced Materials Department, University of Newcastle upon Tyne, Newcastle upon Tyne (United Kingdom); Font, Josep [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain)]. E-mail: jose.font@urv.cat

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (P{sub O{sub 2}}) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P{sub O{sub 2}} were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of P{sub O{sub 2}}, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD{sub RB}) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

  19. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    International Nuclear Information System (INIS)

    Suarez-Ojeda, Maria Eugenia; Kim, Jungkwon; Carrera, Julian; Metcalfe, Ian S.; Font, Josep

    2007-01-01

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (P O 2 ) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P O 2 were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of P O 2 , which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD RB ) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture

  20. Partial catalytic oxidation of CH{sub 4} to synthesis gas for power generation - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mantzaras, I.; Schneider, A.

    2006-03-15

    The partial oxidation of methane to synthesis gas over rhodium catalysts has been investigated experimentally and numerically in the pressure range of 4 to 10 bar. The methane/oxidizer feed has been diluted with large amounts of H{sub 2}O and CO{sub 2} (up to 70% vol.) in order to simulate new power generation cycles with large exhaust gas recycle. Experiments were carried out in an optically accessible channel-flow reactor that facilitated laser-based in situ measurements, and also in a subscale gas-turbine catalytic reactor. Full-elliptic steady and transient two-dimensional numerical codes were used, which included elementary hetero-/homogeneous chemical reaction schemes. The following are the key conclusions: a) Heterogeneous (catalytic) and homogeneous (gas-phase) schemes have been validated for the partial catalytic oxidation of methane with large exhaust gas recycle. b) The impact of added H{sub 2}O and CO{sub 2} has been elucidated. The added H{sub 2}O increased the methane conversion and hydrogen selectivity, while it decreased the CO selectivity. The chemical impact of CO{sub 2} (dry reforming) was minimal. c) The numerical model reproduced the measured catalytic ignition times. It was further shown that the chemical impact of H{sub 2}O and CO{sub 2} on the catalytic ignition delay times was minimal. d) The noble metal dispersion increased with different support materials, in the order Rh/{alpha}-Al{sub 2}O{sub 3}, Rh/ZrO{sub 2}, and Rh/Ce-ZrO{sub 2}. An evident relationship was established between the noble metal dispersion and the catalytic behavior. (authors)

  1. Partial oxidation process for producing a stream of hot purified gas

    Science.gov (United States)

    Leininger, T.F.; Robin, A.M.; Wolfenbarger, J.K.; Suggitt, R.M.

    1995-03-28

    A partial oxidation process is described for the production of a stream of hot clean gas substantially free from particulate matter, ammonia, alkali metal compounds, halides and sulfur-containing gas for use as synthesis gas, reducing gas, or fuel gas. A hydrocarbonaceous fuel comprising a solid carbonaceous fuel with or without liquid hydrocarbonaceous fuel or gaseous hydrocarbon fuel, wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H{sub 2}, CO, CO{sub 2}, H{sub 2}O, CH{sub 4}, NH{sub 3}, HCl, HF, H{sub 2}S, COS, N{sub 2}, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is split into two streams which are separately deslagged, cleaned and recombined. Ammonia in the gas mixture is catalytically disproportionated into N{sub 2} and H{sub 2}. The ammonia-free gas stream is then cooled and halides in the gas stream are reacted with a supplementary alkali metal compound to remove HCl and HF. Alkali metal halides, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000 F. 1 figure.

  2. High-temperature oxidation behavior of Ti3AlC2 in air

    Institute of Scientific and Technical Information of China (English)

    XU Xue-wen; LI Yang-xian; ZHU Jiao-qun; MEI Bing-chu

    2006-01-01

    Not only the isothermal oxidation behaviors at 900-1 300 ℃ for 20 h in air of bulk Ti3AlC2 with 2.8% TiC which was sintered by hot pressing with the additive of silicon,but also the cyclic oxidation behavior at 1 100-1 300 °C for 30 cycles,were investigated by using TG,XRD,SEM. The isothermal and cyclic oxidation behaviors generally follow a parabolic rate law. The parabolic rate constants of the former increased from 1.39×10-10 kg2/(m4·s) at 900 ℃ to 5.56×10-9 kg2/(m4·s) at 1 300 ℃. The calculated activation energy is 136.45 kJ/mol. The oxidation products are á-Al2O3 and little TiO2 at 900-1 000 ℃,however when the temperature is raised up to 1 200 ℃,TiO2 partially reacts to Al2TiO5,and the reaction is completed at 1 300 ℃. This demonstrates that Ti3AlC2 has excellent oxidation resistance and good thermal shock because the dense continuous oxide scale consists of mass á-Al2O3 and little TiO2 and/or Al2TiO5. Generally,the oxide scale is grown by the inward diffusion of O2- and the outward diffusion of Ti4+ and Al3+.

  3. The influence of the oxygen partial pressure on the quasi-ternary system Cr-Mn-Ti-oxide

    International Nuclear Information System (INIS)

    Garcia-Rosales, C.; Schulze, H.A.; Naoumidis, A.; Nickel, H.

    1991-05-01

    The passivation layers formed by the oxidizing corrosion of high temperature alloys consist primarily of oxides and mixed oxides of the elements chromium, manganese and titanium. For a reproducible formation and characterization of such oxide layers it is necessary to know the phase equilibria of these oxide systems at temperature and oxygen partial pressure conditions which will be relevant during their application. For the investigation of the quasi-ternary system Cr-Mn-Ti-oxide, oxide powders were prepared and annealed at 1000deg C under different oxygen partial pressures ranging from 0.21 bar to 10 -21 bar. Phase identification and determination of lattice parameter using X-ray diffraction analysis as well as the direct measurement of phase boundaries as a function of oxygen partial pressure using the emf-methode were carried out for these investigations. In the quasi-ternary system Cr-Mn-Ti-oxide the spinels play a decisive role in the oxigen partial pressure range examined. The spinel MnCr 2 O 4 may be regarded as the most significant compound. Part of the chronium can be replaced by trivalent manganese at high oxygen partial pressures and by trivalent titanium at low pressures, and the formation of a solid solution with the spinel Mn 2 TiO 4 is possible in all cases. In this way a coherent single-phase spinel region is observed which extends over the entire oxygen partial pressure range form 0.21 bar to 10 -21 bar examined at 1000deg C. (orig.) [de

  4. Identification of key nitrous oxide production pathways in aerobic partial nitrifying granules.

    Science.gov (United States)

    Ishii, Satoshi; Song, Yanjun; Rathnayake, Lashitha; Tumendelger, Azzaya; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2014-10-01

    The identification of the key nitrous oxide (N2O) production pathways is important to establish a strategy to mitigate N2O emission. In this study, we combined real-time gas-monitoring analysis, (15)N stable isotope analysis, denitrification functional gene transcriptome analysis and microscale N2O concentration measurements to identify the main N2O producers in a partial nitrification (PN) aerobic granule reactor, which was fed with ammonium and acetate. Our results suggest that heterotrophic denitrification was the main contributor to N2O production in our PN aerobic granule reactor. The heterotrophic denitrifiers were probably related to Rhodocyclales bacteria, although different types of bacteria were active in the initial and latter stages of the PN reaction cycles, most likely in response to the presence of acetate. Hydroxylamine oxidation and nitrifier denitrification occurred, but their contribution to N2O emission was relatively small (20-30%) compared with heterotrophic denitrification. Our approach can be useful to quantitatively examine the relative contributions of the three pathways (hydroxylamine oxidation, nitrifier denitrification and heterotrophic denitrification) to N2O emission in mixed microbial populations. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  5. Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

    2011-07-01

    High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

  6. Wet air oxidation of seedcorn wastes containing pesticides and insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, M.; Schlaefer, O.; Onyeche, T.I.; Schroeder, C.; Bormann, H.; Schaefer, S. [CUTEC-Inst. GmbH (Clausthal Environment Technology Inst.), Clausthal-Zellerfeld (Germany)

    2003-07-01

    Wet air oxidation as an alternative treatment process to pyrolysis and combustion of seedcorn wastes was investigated in lab-scale experiments. Due to solid condition of the seed corn waste, the process has been adapted by repeated spraying of water on the seed corn bulk to avoid the production of sludge and its subsequent dewatering. Original seed corns from industrial production plants were used for a degradation kinetic study under smooth wet air oxidation conditions. The temperatures were between 80 and 150 C, the pressure from 1 to 4.5 bar and the pH at different values from 3 to 13. Degradation rates for five different compounds of pesticides and insecticides, namely Imidacloprid, Thiram, Hymexazol, Carbofuran and Tefluthrin were conducted. These compounds represent the recently used in agricultural seedcorn applications. The degradation rate depends linearly on temperature between 80 and 150 C. At 120 C the lowest degradation rate was found for Tefluthrin by 25 mg/h per L reaction volume while the highest degradation rate to be conducted was for Imidacloprid at 363 mg/h L. (orig.)

  7. Cathodic reduction of the duplex oxide films formed on copper in air with high relative humidity at 60 deg C

    International Nuclear Information System (INIS)

    Seo, M.; Ishikawa, Y.; Kodaira, M.; Sugimoto, A.; Nakayama, S.; Watanabe, M.; Furuya, S.; Minamitani, R.; Miyata, Y.; Nishikata, A.; Notoya, T.

    2005-01-01

    The cathodic reduction of duplex air-formed oxide film on copper was performed at a constant current density of i c = -50 μA cm -2 in deaerated 0.1 M KCl solution to investigate the sequence of cathodic reduction of each oxide layer and its mechanism. The single-phase thick CuO film on copper was also cathodically reduced at i c = -50 μA cm -2 or -2.5 mA cm -2 . The surface characterizations of the air-formed oxide film and single-phase CuO film before cathodic reduction and after partial or complete cathodic reduction were performed by XPS and X-ray diffraction, respectively. The two plateau regions appeared in the potential vs. time curve during cathodic reduction of the duplex air-formed oxide film on copper, while one plateau region was observed in the potential-time curve during cathodic reduction of the single-phase CuO film on copper. The potential in the first plateau region for the air-formed film coincided with that in the plateau region for the CuO film. The results of XPS and X-ray diffraction suggested that in the first plateau region, the outer CuO layer is directly reduced to metallic Cu, while in the second plateau region, the inner Cu 2 O layer is reduced to metallic Cu

  8. Temperature oscillations in methanol partial oxidation reactor for the production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinsu; Byeon, Jeonguk; Seo, Il Gyu; Lee, Hyun Chan; Kim, Dong Hyun; Lee, Jietae [Kyungpook National University, Daegu (Korea, Republic of)

    2013-04-15

    Methanol partial oxidation (POX) is a well-known reforming reaction for the production of hydrogen from methanol. Since POX is relatively fast and highly exothermic, this reforming method will be efficient for the fast start-up and load-following operation. However, POX generates hot spots around catalyst and even oscillations in the reactor temperature. These should be relieved for longer operations of the reactor without catalyst degradations. For this, temperature oscillations in a POX reactor are investigated experimentally. Various patterns of temperature oscillations according to feed flow rates of reactants and reactor temperatures are obtained. The bifurcation phenomena from regular oscillations to chaotic oscillations are found as the methanol flow rate increases. These experimental results can be used for theoretical analyses of oscillations and for designing safe reforming reactors.

  9. Temperature oscillations in methanol partial oxidation reactor for the production of hydrogen

    International Nuclear Information System (INIS)

    Kim, Jinsu; Byeon, Jeonguk; Seo, Il Gyu; Lee, Hyun Chan; Kim, Dong Hyun; Lee, Jietae

    2013-01-01

    Methanol partial oxidation (POX) is a well-known reforming reaction for the production of hydrogen from methanol. Since POX is relatively fast and highly exothermic, this reforming method will be efficient for the fast start-up and load-following operation. However, POX generates hot spots around catalyst and even oscillations in the reactor temperature. These should be relieved for longer operations of the reactor without catalyst degradations. For this, temperature oscillations in a POX reactor are investigated experimentally. Various patterns of temperature oscillations according to feed flow rates of reactants and reactor temperatures are obtained. The bifurcation phenomena from regular oscillations to chaotic oscillations are found as the methanol flow rate increases. These experimental results can be used for theoretical analyses of oscillations and for designing safe reforming reactors

  10. Partial thermodynamic functions of hydrogen in complex hydrated vanadium(5) and tungsten(6) oxides

    International Nuclear Information System (INIS)

    Volkov, V.L.; Zakharova, G.S.

    2003-01-01

    The partial thermodynamic characteristics of hydrogen in the complex hydrated vanadium(5) and tungsten(6) oxides, obtained through the sol-gel method, of the general formula H 2 V 12-y W y O 31+δ ·nH 2 O (0 ≤ x ≤ 0.33) are determined through the emf method. The changes in these values (ΔG-bar(H 2 ), ΔH-bar(H 2 ) and ΔS-bar(H 2 )) in dependence on the compound composition are discussed. It is established that ΔG-bar(H 2 ) phases, amorphous to X-rays are determined by the ΔS-bar(H 2 ) value and crystalline ones by ΔH-bar(H 2 ). The scheme of the phase relationships of the H 2 O-H-WO 3 -V 2 O 5 system, whereto the given phases are related are presented [ru

  11. Microbial resource management for the mitigation of nitrous oxide emissions from the Partial Nitritation- Anammox process

    DEFF Research Database (Denmark)

    Blum, Jan-Michael

    Urban wastewater treatment plants are designed to remove pathogens and pollutants from wastewater in order to provide sanitation and to protect receiving water bodies from eutrophication. Reactive nitrogen, mainly in the form of ammonium, is one of the components in wastewater that is converted...... to dinitrogen gas during treatment. The Partial Nitritation-Anammox process (PNA) uses the capacity of autotrophic aerobic and anaerobic ammonia oxidizing bacteria (AOB and AnAOB) to perform this task. The process is mainly applied to treat ammonium-rich wastewater streams with low concentrations of organic...... with the specific ammonia removal rate, while during non-aerated phases net N2O production rates were positively correlated with the nitrite concentration (NO2-). Operation of PNA at reduced specific ammonia removal rates is, therefore, a feasible strategy to mitigate N2O emissions. However, when high ammonium...

  12. Air Flow and Pressure Drop Measurements Across Porous Oxides

    Science.gov (United States)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus air flow is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected flow decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of air flow versus processing parameters and the resulting porosity size and distribution.

  13. Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

    DEFF Research Database (Denmark)

    Sun, Yuexia; Fang, Lei; Wyon, David Peter

    2008-01-01

    The experiment presented in this report was performed in a simulated aircraft cabin to evaluate the air cleaning effects of two air purification devices that used photocatalytic oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjective human assessment...

  14. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Yuting [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China); Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Descorme, Claude, E-mail: claude.descorme@ircelyon.univ-lyon1.fr [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2014-07-15

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pH{sub PZC}, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

  15. Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

    Science.gov (United States)

    Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng

    2016-03-01

    Nitrous oxide (N2O) production during the partial denitrification process with nitrate (NO3(-)-N) to nitrite (NO2(-)-N) transformation ratio of 80% was investigated in this study. Results showed that N2O was seldom observed before complete depletion of NO3(-)-N, but it was closely related to the reduction of NO2(-)-N rather than NO3(-)-N. High COD/NO3(-)-N was in favor of N2O production in partial denitrification with high NO2(-)-N accumulation. It was seriously enhanced at constant acidic pH due to the free nitrous acid (FNA) inhibition. However, the N2O production was much lower at initial pH of 5.5 and 6.5 due to the pH increase during denitrification process. Significantly, the pH turning point could be chosen as a controlled parameter to denote the end of NO3(-)-N reduction, which could not only achieve high NO2(-)-N accumulation but also decrease the N2O production significantly for practical application. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Oxidation of vanadium carbide in air; Oxidacion de carburo de vanadio en aire

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, A.; Troiani, L.; Materan, E. [Universidad Simon Bolivar, Depto. de la Ciencia de los Materiales, Grupo de Ingenieria de Superficies e Interfaces, Caracas, Venezuela, (Venezuela)

    1998-12-31

    It was studied the samples oxidation of vanadium carbide (V{sub 8}C{sub 7}), synterized and in powder, in order to know the temperature influence and the aggregation state in the kinetics and the oxidation products. The assays were realized in static air, at temperature between 600 y 750 Centigrade, between 6 and 24 hours periods. The gaseous products were analyzed through gas chromatography while the condensates ones were analyzed through optical microscopy and scanning electron microscopy, X-ray diffraction and chemical analysis by X-ray fluorescence analysis. It was found that in the V{sub 8}C{sub 7} oxidation occurs two basic processes: the gaseous oxides production which results of the carbon oxidation, fundamentally CO{sub 2}, and the vanadium condensate oxides production, fundamentally V{sub 2}O{sub 5}. In the synterized samples assayed under 650 Centigrade, the kinetics is lineal with loss of mass, suggesting a control by the formation of gaseous products in the sample surface, while in the synterized samples assayed over 650 Centigrade, it occurs a neat gain of mass, which is attributed to vanadium pentoxide fusion. These processes produce stratified layers of V{sub 2}O{sub 5} although at higher temperatures also it was detected V{sub 2}O{sub 4}. The superficial area effect is revealed in what the powder samples always experiment a mass neat increase in all essay temperatures, being the condensate oxidation products, fundamentally V{sub 2}O{sub 5} and V{sub 6}O{sub 13}. (Author)

  17. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U. J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A. M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  18. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption – Catalytic wet air oxidation on activated carbons

    International Nuclear Information System (INIS)

    Quesada-Peñate, I.; Julcour-Lebigue, C.; Jáuregui-Haza, U.J.; Wilhelm, A.M.; Delmas, H.

    2012-01-01

    Highlights: ► Three activated carbons (AC) compared as adsorbents and oxidation catalysts. ► Similar evolution for catalytic and adsorptive properties of AC over reuses. ► Acidic and mesoporous AC to be preferred, despite lower initial efficiency. ► Oxidative degradation of paracetamol improves biodegradability. ► Convenient hybrid adsorption–regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  19. Air Oxidation Behaviors of Zircaloy-4 Cladding During a LOCA In Spent Fuel Pool

    International Nuclear Information System (INIS)

    Bang, Je Geon; Chun, Tae Hyun; Kim, Sun Ki; Koo, Yang Hyun

    2014-01-01

    It is well known that air oxidation induces a serious degradation of the Zircaloy cladding material, compared with steam oxidation. From the oxidant point of view, in comparison with steam, chemical heat release during oxidation in air is higher by 80%, which may lead to a more rapid degradation of the Zircaloy cladding, and further evolution of the accident.. Additionally, the oxidation kinetics in air is much faster than in steam due to the formation of non-protective oxide layer. From the safety point of view, the barrier effect of the cladding against release of fission products is lost much earlier in air compared to steam. The objective of this study is to investigate the oxidation behaviors of fuel cladding in two different conditions such as isothermal and transient condition and to generate its kinetic data under an accident condition in the spent fuel pool. In this study, the oxidation behaviors and its kinetics of the Zircaloy-4 were investigated in air environment for various air ingress scenarios in the temperature range 600 .deg. C-1,400 .deg. C by thermo-gravimetric analysis. In this study, the oxidation behaviors of the Zircaloy-4 for both isothermal condition and transient condition were investigated in air environment. In comparison with isothermal condition, the retardation of oxidation rate in transient condition was observed at both 1,200 .deg. C and 1,400 .deg. C. This seems to be ascribed to the effect of thin oxide formed during a heating

  20. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING / FEASIBILITY STUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER,M; HONG,G

    2005-01-01

    Under Cooperative Agreement No. DE-FC36-00GO10529 for the Department of Energy, General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The Key potential advantages of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reaching and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carreid out at the University of Hawaii at Manoa (UHM) as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an acitvated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low

  1. Catalyst development and systems analysis of methanol partial oxidation for the fuel processor - fuel cell integration

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E; Mizsey, P; Hottinger, P; Truong, T B; Roth, F von; Schucan, Th H [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Methanol partial oxidation (pox) to produce hydrogen for mobile fuel cell applications has proved initially more successful than hydrocarbon pox. Recent results of catalyst screening and kinetic studies with methanol show that hydrogen production rates have reached 7000 litres/hour/(litre reactor volume) for the dry pox route and 12,000 litres/hour/(litre reactor volume) for wet pox. These rates are equivalent to 21 and 35 kW{sub th}/(litre reactor volume) respectively. The reaction engineering problems remain to be solved for dry pox due to the significant exotherm of the reaction (hot spots of 100-200{sup o}C), but wet pox is essentially isothermal in operation. Analyses of the integrated fuel processor - fuel cell systems show that two routes are available to satisfy the sensitivity of the fuel cell catalysts to carbon monoxide, i.e. a preferential oxidation reactor or a membrane separator. Targets for individual system components are evaluated for the base and best case systems for both routes to reach the combined 40% efficiency required for the integrated fuel processor - fuel cell system. (author) 2 figs., 1 tab., 3 refs.

  2. Oxidative pyrolysis of kraft lignin in a bubbling fluidized bed reactor with air

    International Nuclear Information System (INIS)

    Li, Dongbing; Briens, Cedric; Berruti, Franco

    2015-01-01

    Fast pyrolysis of kraft lignin with partial (air) oxidation was studied in a bubbling fluidized bed reactor at reaction temperatures of 773 and 823 K. The bio-oil vapors were fractionated using a series of three condensers maintained at desired temperatures, providing a dry bio-oil with less than 1% water and over 96% of the total bio-oil energy. Oxygen feed was varied to study its effect on yield, composition, and energy recovery in the gas, char and oil products. The addition of oxygen to the pyrolysis process increased the production of gases such as CO and CO 2 . It also changed the dry bio-oil properties, reducing its heating value, increasing its oxygen content, reducing its average molecular weight and tar concentration, while increasing its phenolics concentration. The lower reaction temperature of 773 K was preferred for both dry bio-oil yield and quality. Autothermal operation of the pyrolysis process was achieved with an oxygen feed of 72 or 54 g per kg of biomass at the reaction temperatures of 773 and 823 K, respectively. Autothermal operation reduced both yield and total energy content of the dry bio-oil, with relative reductions of 24 and 20% for the yield, 28 and 23% for the energy content, at 773 and 823 K. - Highlights: • Autothermal pyrolysis of Kraft lignin is possible with introduction of air. • Under autothermal conditions, 24% of the dry bio-oil chemicals are lost at 773 K. • Partial oxidation helps produce more simple phenols and less pyrolytic lignin. • Bio-oil from lignin pyrolysis has a very high phenolics concentration

  3. Bio-oil steam reforming, partial oxidation or oxidative steam reforming coupled with bio-oil dry reforming to eliminate CO{sub 2} emission

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xun [State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Lu, Gongxuan [State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2010-07-15

    Biomass is carbon-neutral and utilization of biomass as hydrogen resource shows no impact on atmospheric CO{sub 2} level. Nevertheless, a significant amount of CO{sub 2} is always produced in biomass gasification processes. If the CO{sub 2} produced can further react with biomass, then the biomass gasification coupled with CO{sub 2} reforming of biomass will result in a net decrease of CO{sub 2} level in atmosphere and produce the chemical raw material, syngas. To achieve this concept, a ''Y'' type reactor is developed and applied in bio-oil steam reforming, partial oxidation, or oxidative steam reforming coupled with CO{sub 2} reforming of bio-oil to eliminate the emission of CO{sub 2}. The experimental results show that the reaction systems can efficiently suppress the emission of CO{sub 2} from various reforming processes. The different coupled reaction systems generate the syngas with different molar ratio of CO/H{sub 2}. In addition, coke deposition is encountered in the different reforming processes. Both catalysts and experimental parameters significantly affect the coke deposition. Ni/La{sub 2}O{sub 3} catalyst shows much higher resistivity toward coke deposition than Ni/Al{sub 2}O{sub 3} catalyst, while employing high reaction temperature is vital for elimination of coke deposition. Although the different coupled reaction systems show different characteristic in terms of product distribution and coke deposition, which all can serve as methods for storage of the carbon from fossil fuels or air. (author)

  4. Hybrid Nitrous Oxide Production from a Partial Nitrifying Bioreactor: Hydroxylamine Interactions with Nitrite.

    Science.gov (United States)

    Terada, Akihiko; Sugawara, Sho; Hojo, Keisuke; Takeuchi, Yuki; Riya, Shohei; Harper, Willie F; Yamamoto, Tomoko; Kuroiwa, Megumi; Isobe, Kazuo; Katsuyama, Chie; Suwa, Yuichi; Koba, Keisuke; Hosomi, Masaaki

    2017-03-07

    The goal of this study was to elucidate the mechanisms of nitrous oxide (N 2 O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched from a sequencing batch reactor (SBR) were subjected to N 2 O production pathway tests. The N 2 O pathway test was initiated by supplying an inorganic medium to ensure an initial NH 4 + -N concentration of 160 mg-N/L, followed by 15 NO 2 - (20 mg-N/L) and dual 15 NH 2 OH (each 17 mg-N/L) spikings to quantify isotopologs of gaseous N 2 O ( 44 N 2 O, 45 N 2 O, and 46 N 2 O). N 2 O production was boosted by 15 NH 2 OH spiking, causing exponential increases in mRNA transcription levels of AOB functional genes encoding hydroxylamine oxidoreductase (haoA), nitrite reductase (nirK), and nitric oxide reductase (norB) genes. Predominant production of 45 N 2 O among N 2 O isotopologs (46% of total produced N 2 O) indicated that coupling of 15 NH 2 OH with 14 NO 2 - produced N 2 O via N-nitrosation hybrid reaction as a predominant pathway. Abiotic hybrid N 2 O production was also observed in the absence of the AOB-enriched biomass, indicating multiple pathways for N 2 O production in a PN bioreactor. The additional N 2 O pathway test, where 15 NH 4 + was spiked into 400 mg-N/L of NO 2 - concentration, confirmed that the hybrid N 2 O production was a dominant pathway, accounting for approximately 51% of the total N 2 O production.

  5. Enzymatic Upgrading of Heavy Crudes via Partial Oxidation or Conversion of PAHs

    Energy Technology Data Exchange (ETDEWEB)

    Borole, A P; Davison, B H; Kuritz, T

    2002-07-01

    The objective of this program was to investigate new enzyme-based technologies for upgrading of heavy oils. Enzymes were selected for screening from those capable of conversion of polyaromatic hydrocarbons (PAHs) reported in the literature. Oxidative reactions of PAHs using hydrogen peroxide as an oxidant with conversion to partially oxidized products were used. The enzymes (lignin peroxidase, cytochrome c) were tested in various organic solvents and found to loose activity in pure organic solvents. A thermodynamic analysis revealed lack of effective interaction between the substrate and enzyme as the cause for low activity. The protein cytochrome c was modified to work in organic media by chemical hydrophobic group attachment. Two different modifications were made: attachment of polyethylene glycol (PEG) and alkyl groups. Alkyl groups, being small could be attached at interior locations within the core of the enzyme and possibly near the active site. Increase in the threshold solvent concentration where maximum enzyme activity occurred indicated potential of this strategy for effective enzyme-substrate interaction. Further improvements in enzyme activity called for other diverse methods due to the unavailability of sufficient chemical modification sites. Genetic techniques were therefore explored for further improvements. These experiments focused on cloning of a gene for the fungal enzyme lignin peroxidase (lip) into yeast Pichia pastoris, which would allow easy manipulation of the gene. However, differences in the fungal and yeast cellular machinery impeded significant expression of the fungal enzyme. Several strategies were explored to allow higher-level expression of the enzyme, which was required for enzyme improvement. The strategies used in this investigation are described in the report. Industrial in-kind support was available throughout the project period. review of the research results was carried out on a regular basis (bimonthly reports and annual

  6. Air trichloroethylene oxidation in a corona plasma-catalytic reactor

    International Nuclear Information System (INIS)

    Masoomi-Godarzi, S.; Ranji-Burachaloo, H.; Khodadadi, A.A.; Vesali-Naseh, M.; Mortazavi, Y.

    2014-01-01

    The oxidative decomposition of trichloroethylene (TCE; 300 ppm) by non-thermal corona plasma was investigated in dry air at atmospheric pressure and room temperature, both in the absence and presence of catalysts including MnO x , CoO x . The catalysts were synthesized by a co-precipitation method. The morphology and structure of the catalysts were characterized by BET surface area measurement and Fourier Transform Infrared (FTIR) methods. Decomposition of TCE and distribution of products were evaluated by a gas chromatograph (GC) and an FTIR. In the absence of the catalyst, TCE removal is increased with increases in the applied voltage and current intensity. Higher TCE removal and CO 2 selectivity is observed in presence of the corona and catalysts, as compared to those with the plasma alone. The results show that MnO x and CoO x catalysts can dissociate the in-plasma produced ozone to oxygen radicals, which enhances the TCE decomposition. (author)

  7. Air trichloroethylene oxidation in a corona plasma-catalytic reactor

    Science.gov (United States)

    Masoomi-Godarzi, S.; Ranji-Burachaloo, H.; Khodadadi, A. A.; Vesali-Naseh, M.; Mortazavi, Y.

    2014-08-01

    The oxidative decomposition of trichloroethylene (TCE; 300 ppm) by non-thermal corona plasma was investigated in dry air at atmospheric pressure and room temperature, both in the absence and presence of catalysts including MnOx, CoOx. The catalysts were synthesized by a co-precipitation method. The morphology and structure of the catalysts were characterized by BET surface area measurement and Fourier Transform Infrared (FTIR) methods. Decomposition of TCE and distribution of products were evaluated by a gas chromatograph (GC) and an FTIR. In the absence of the catalyst, TCE removal is increased with increases in the applied voltage and current intensity. Higher TCE removal and CO2 selectivity is observed in presence of the corona and catalysts, as compared to those with the plasma alone. The results show that MnOx and CoOx catalysts can dissociate the in-plasma produced ozone to oxygen radicals, which enhances the TCE decomposition.

  8. Plutonium transport for the oxide form. Air and road accidentology

    International Nuclear Information System (INIS)

    Degrange, J.P.; Hubert, P.; Pages, P.

    1989-07-01

    The aim of the study is to define the probability of accident that can be applied to a packaging for plutonium oxide transport. The analysis is designed essentially for packagings of few tons with impact resistance corresponding to a speed of 10 m/s but can be used for packagings with a resistance corresponding to IAEA tests. This work is based on analysis and processing of 2 accident files: one on road accidents, the other on air accidents. Computer codes are developed, from one hand, to obtain stress indicator distribution by Monte Carlo methods and on the other hand to link these distributions to itinerary parameters. Previous similar studies are examined and compared to figures obtained here and explained as far as possible [fr

  9. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    DEFF Research Database (Denmark)

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram

    2012-01-01

    oxidation of methane, the catalyst reduced from the end to the beginning of the catalyst bed and oxidized again toward the end as soon as the entire catalyst bed was reduced. On an entirely oxidized catalyst bed, only total oxidation of methane was observed and consumed the oxygen until the conditions...... of the Pd particles at increasing age of the catalyst was observed, which leads to a lower oscillation frequency. Effects of particle size, oven temperature, and oxygen/methane ratio on the oscillation behavior were studied in detail. The deactivation period (reoxidation of Pd) was much less influenced...... by the oven temperature than the ignition behavior of the catalytic partial oxidation of methane. This indicates that deactivation is caused by an autoreduction of the palladium at the beginning of the catalyst bed due to the high temperature achieved by total oxidation of methane....

  10. Change of properties after oxidation of IG-11 graphite by air and CO2 gas

    International Nuclear Information System (INIS)

    Lim, Yun-Soo; Chi, Se-Hwan; Cho, Kwang-Yun

    2008-01-01

    Artificial graphite is typically manufactured by carbonization of a shaped body of a kneaded mixture using granular cokes as a filler and pitch as a binder. It undergoes a pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation in air or a CO 2 atmosphere on IG-11 graphite samples is investigated in this study. The results show a localized oxidation process that progressively reveals the large coke particles with increasing level of overall weight loss in air. The surface of the graphite was peeled off and no change was found in the specific gravity after air oxidation. However, the specific gravity of graphite was continuously decreased by CO 2 oxidation. The decrease in the specific gravity by CO 2 oxidation was due to CO 2 gas that progressed from the surface to the interior. The pore shape after CO 2 oxidation differed from that under air oxidation

  11. Plasma-assisted partial oxidation of methane at low temperatures: numerical analysis of gas-phase chemical mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Goujard, Valentin; Nozaki, Tomohiro; Yuzawa, Shuhei; Okazaki, Ken [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, 1528552, Tokyo (Japan); Agiral, Anil, E-mail: tnozaki@mech.titech.ac.jp [Mesoscale Chemical Systems, MESA Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)

    2011-07-13

    Methane partial oxidation was investigated using a plasma microreactor. The experiments were performed at 5 and 300 deg. C. Microreactor configuration allows an efficient evacuation of the heat generated by methane partial oxidation and dielectric barrier discharges, allowing at the same time a better temperature control. At 5 deg. C, liquid condensation of low vapour pressure compounds, such as formaldehyde and methanol, occurs. {sup 1}H-NMR analysis allowed us to demonstrate significant CH{sub 3}OOH formation during plasma-assisted partial oxidation of methane. Conversion and product selectivity were discussed for both temperatures. In the second part of this work, a numerical simulation was performed and a gas-phase chemical mechanism was proposed and discussed. From the comparison between the experimental results and the simulation it was found that CH{sub 3}OO{center_dot} formation has a determinant role in oxygenated compound production, since its fast formation disfavoured radical recombination. At 5 deg. C the oxidation leads mainly towards oxygenated compound formation, and plasma dissociation was the major phenomenon responsible for CH{sub 4} conversion. At 300 deg. C, higher CH{sub 4} conversion resulted from oxidative reactions induced by {center_dot}OH radicals with a chemistry predominantly oxidative, producing CO, H{sub 2}, CO{sub 2} and H{sub 2}O.

  12. Oxidation behavior of stainless steel 430 and 441 at 800 C in single (air/air) and dual atmosphere (air/hydrogen) exposures

    Energy Technology Data Exchange (ETDEWEB)

    Rufner, J.; Gannon, P.; White, P.; Deibert, M.; Teintze, S. [Chemical and Biological Engineering, Montana State University, 306 Cobleigh Hall, Bozeman, MT 59717-3920 (United States); Smith, R.; Chen, H. [Physics, Montana State University, 306 Cobleigh Hall, Bozeman, MT 59717-3920 (United States)

    2008-02-15

    Intermediate temperature ({proportional_to}800 {sup o}C) planar solid oxide fuel cells (SOFCs) allow the use of ferritic stainless steel (FSS) interconnects. SOFC FSS interconnects are used to stack individual cells into series, and are simultaneously exposed to air on the cathode side and fuel on the anode side, creating a 'dual atmosphere' exposure. The thermally grown oxide (TGO) layers on the air side of FSSs 430 and 441 were analyzed as a function of simulated dual atmosphere exposures (moist air/moist hydrogen) for up to 300 h. FSS 430 showed some changes in oxidation behavior, with a slight Fe concentration increase and localized Fe{sub 2}O{sub 3} nodule formation observed in the dual atmosphere TGO layer relative to its single atmosphere (air/air) counterpart. Significantly accelerated and anomalous oxidation was observed with FSS 441 subjected to dual atmosphere exposures compared with air/air exposures. The TGO layer formed on the 441 exposed to air/air was comprised of Mn-rich, Cr and Fe-containing isomorphic spinel surface crystallites, with a Cr{sub 2}O{sub 3} (eskolaite)-based bottom layer, having a total TGO layer thickness of <2{mu} m after 300 h. In contrast, the TGO layer formed on 441 during dual atmosphere exposure was much faster-growing (>6{mu} m in 20 h) and exhibited a continuous, porous Fe{sub 2}O{sub 3}-rich surface layer with a relatively thin (<2{mu} m) sublayer of similar composition to the TGO layer formed during the air/air exposure. Spontaneous TGO layer spallation was also observed for the air side of 441 exposed to dual atmosphere for >100h. The observed oxidation behavior and TGO layer evolution of 441 in both air/air and dual atmosphere are presented, with possible mechanisms and implications discussed. (author)

  13. Oxidation behavior of U-Si compounds in air from 25 to 1000 C

    Science.gov (United States)

    Sooby Wood, E.; White, J. T.; Nelson, A. T.

    2017-02-01

    The air oxidation behavior of U3Si2, USi, and U3Si5 is studied from room temperature to 1000 C. The onsets of breakaway oxidation for each compound are identified during synthetic air ramps to 1000 C using thermogravimetric analysis. Isothermal air oxidation tests are performed below and above the breakaway oxidation onset to discern the oxidation kinetic behavior of these candidate accident tolerant fuel forms. Uranium metal is tested in the same manner to provide a reference for the oxidation behavior. Thermogravimetric, x-ray diffraction, and scanning electron microscopy analysis are presented here along with a discussion of the oxidation behavior of these materials and the impact of the lack of oxidation resistance to their deployment as accident tolerant nuclear fuels.

  14. Oxidation behavior of U-Si compounds in air from 25 to 1000 C

    Energy Technology Data Exchange (ETDEWEB)

    Sooby Wood, E., E-mail: sooby@lanl.gov; White, J.T.; Nelson, A.T.

    2017-02-15

    The air oxidation behavior of U{sub 3}Si{sub 2}, USi, and U{sub 3}Si{sub 5} is studied from room temperature to 1000 C. The onsets of breakaway oxidation for each compound are identified during synthetic air ramps to 1000 C using thermogravimetric analysis. Isothermal air oxidation tests are performed below and above the breakaway oxidation onset to discern the oxidation kinetic behavior of these candidate accident tolerant fuel forms. Uranium metal is tested in the same manner to provide a reference for the oxidation behavior. Thermogravimetric, x-ray diffraction, and scanning electron microscopy analysis are presented here along with a discussion of the oxidation behavior of these materials and the impact of the lack of oxidation resistance to their deployment as accident tolerant nuclear fuels.

  15. Partial oxidation of TiN coating by hydrothermal treatment and ozone treatment to improve its osteoconductivity

    International Nuclear Information System (INIS)

    Shi, Xingling; Xu, Lingli; Le, Thi Bang; Zhou, Guanghong; Zheng, Chuanbo; Tsuru, Kanji; Ishikawa, Kunio

    2016-01-01

    Dental implants made of pure titanium suffer from abrasion and scratch during routine oral hygiene procedures. This results in an irreversible surface damage, facilitates bacteria adhesion and increases risk of peri-implantitis. To overcome these problems, titanium nitride (TiN) coating was introduced to increase surface hardness of pure titanium. However, the osteoconductivity of TiN is considered to be similar or superior to that of titanium and its alloys and therefore surface modification is necessary. In this study, TiN coating prepared through gas nitriding was partially oxidized by hydrothermal (HT) treatment and ozone (O 3 ) treatment in pure water to improve its osteoconductivity. The effects of HT treatment and O 3 treatment on surface properties of TiN were investigated and the osteoconductivity after undergoing treatment was assessed in vitro using osteoblast evaluation. The results showed that the critical temperature for HT treatment was 100 °C since higher temperatures would impair the hardness of TiN coating. By contrast, O 3 treatment was more effective in oxidizing TiN surfaces, improving its wettability while preserving its morphology and hardness. Osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression and mineralization were improved on oxidized specimens, especially on O 3 treated specimens, compared with untreated ones. These effects seemed to be consequences of partial oxidation, as well as improved hydrophilicity and surface decontamination. Finally, it was concluded that, partially oxidized TiN is a promising coating to be used for dental implant. - Highlights: • TiN coating surface was oxidized by hydrothermal or ozone treatment while preserving its hardness. • Improved wettability, decontamination and interstitial N promoted osteoblast responses. • Partial oxidation makes TiN a promising coating for dental implant with good osteoconductivity.

  16. Partial oxidation of TiN coating by hydrothermal treatment and ozone treatment to improve its osteoconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xingling [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan); Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); Xu, Lingli, E-mail: linly311@163.com [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Le, Thi Bang [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Zhou, Guanghong [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); Zheng, Chuanbo, E-mail: zjust316@163.com [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Tsuru, Kanji; Ishikawa, Kunio [Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan)

    2016-02-01

    Dental implants made of pure titanium suffer from abrasion and scratch during routine oral hygiene procedures. This results in an irreversible surface damage, facilitates bacteria adhesion and increases risk of peri-implantitis. To overcome these problems, titanium nitride (TiN) coating was introduced to increase surface hardness of pure titanium. However, the osteoconductivity of TiN is considered to be similar or superior to that of titanium and its alloys and therefore surface modification is necessary. In this study, TiN coating prepared through gas nitriding was partially oxidized by hydrothermal (HT) treatment and ozone (O{sub 3}) treatment in pure water to improve its osteoconductivity. The effects of HT treatment and O{sub 3} treatment on surface properties of TiN were investigated and the osteoconductivity after undergoing treatment was assessed in vitro using osteoblast evaluation. The results showed that the critical temperature for HT treatment was 100 °C since higher temperatures would impair the hardness of TiN coating. By contrast, O{sub 3} treatment was more effective in oxidizing TiN surfaces, improving its wettability while preserving its morphology and hardness. Osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression and mineralization were improved on oxidized specimens, especially on O{sub 3} treated specimens, compared with untreated ones. These effects seemed to be consequences of partial oxidation, as well as improved hydrophilicity and surface decontamination. Finally, it was concluded that, partially oxidized TiN is a promising coating to be used for dental implant. - Highlights: • TiN coating surface was oxidized by hydrothermal or ozone treatment while preserving its hardness. • Improved wettability, decontamination and interstitial N promoted osteoblast responses. • Partial oxidation makes TiN a promising coating for dental implant with good osteoconductivity.

  17. Development of a membrane-assisted fluidized bed reactor - 2 - Experimental demonstration and modeling for the partial oxidation of methanol

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Laverman, J.A.; van Sint Annaland, M.; Kuipers, J.A.M.

    2005-01-01

    A small laboratory-scale membrane-assisted fluidized bed reactor (MAFBR) was constructed in order to experimentally demonstrate the reactor concept for the partial oxidation of methanol to formaldehyde. Methanol conversion and product selectivities were measured at various overall fluidization

  18. Palm H-FAME Production through Partially Hydrogenation using Nickel/Carbon Catalyst to Increase Oxidation Stability

    Directory of Open Access Journals (Sweden)

    Ramayeni Elsa

    2018-01-01

    Full Text Available One of the methods to improve the oxidation stability of palm biodiesel is through partially hydrogenation. The production using Nickel/Carbon catalyst to speed up the reaction rate. Product is called Palm H-FAME (Hydrogenated FAME. Partial hydrogenation breaks the unsaturated bond on FAME (Fatty Acid Methyl Ester, which is a key component of the determination of oxidative properties. Changes in FAME composition by partial hydrogenation are predicted to change the oxidation stability so it does not cause deposits that can damage the injection system of diesel engine, pump system, and storage tank. Partial hydrogenation is carried out under operating conditions of 120 °C and 6 bar with 100:1, 100:3, 100:5, 100:10 % wt catalyst in the stirred batch autoclave reactor. H-FAME synthesis with 100:5 % wt Ni/C catalyst can decrease the iodine number which is the empirical measure of the number of unsaturated bonds from 91.78 to 82.38 (g-I2/100 g with an increase of oxidation stability from 585 to 602 minutes.

  19. Effect of surface composition of yttrium-stabilized zirconia on partial oxidation of methane to synthesis gas.

    NARCIS (Netherlands)

    Zhu, J.J.; van Ommen, J.G.; Knoester, A.; Lefferts, Leonardus

    2005-01-01

    Catalytic partial oxidation of methane to synthesis gas (CPOM) over yttrium-stabilized zirconia (YSZ) was studied within a wide temperature window (500¿1100 °C). The catalysts were characterized by X-ray fluorescence (XRF) and low-energy ion scattering (LEIS). The influence of calcination

  20. 77 FR 66398 - Partial Approval and Disapproval of Air Quality Implementation Plans; Arizona; Infrastructure...

    Science.gov (United States)

    2012-11-05

    ...(a)(2)(J) (in part): PSD. Section 110 (a)(2)(K): Air quality modeling and submission of monitoring... fine particulate matter (PM 2.5 ), interstate pollution abatement, and air quality models and modeling... (``Violations; injunctive relief''), 49-463 (``Violations; civil penalties''), and 49- 465 (``Air pollution...

  1. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons.

    Science.gov (United States)

    Quesada-Peñate, I; Julcour-Lebigue, C; Jáuregui-Haza, U J; Wilhelm, A M; Delmas, H

    2012-06-30

    The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. The syngas production by partial oxidation using a homogeneous charge compression ignition engine

    International Nuclear Information System (INIS)

    Yang, Yoon Cheol; Lim, Mun Sup; Chun, Young Nam

    2009-01-01

    It is essential to develop the environment-friendly alternative energies urgently considering the limited fossil fuel and the global warming caused by environmental destruction. In this research, the new technology was studied to produce syngas from methane or simulated biogas with a HCCI reforming engine. The purpose is to provide the basics for the research on biogas treatment mainly comprising of methane and carbon dioxide, the cause of global warming. This experiment was conducted on the changes in syngas concentration according to the variations of oxygen/methane ratio, total flow rate, intake heating temperature, CO 2 in mixture and oxygen enrichment with partial oxidation. Through the parametric screening studies, optimum conditions and their results in this study was taken as follows; The maximum content of syngas was; 27.4% at 0.3 of oxygen/methane ratio, 32.38% at 117.3 L/min of total flow rate, and 35.83% at 355 C of intake heating temperature. 41.06% of syngas was produced at 50.33% of oxygen enrichment ratio. (author)

  3. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection.

    Science.gov (United States)

    Yao, B C; Wu, Y; Yu, C B; He, J R; Rao, Y J; Gong, Y; Fu, F; Chen, Y F; Li, Y R

    2016-03-24

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel 'FRET on Fiber' concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based 'FRET on fiber' configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated 'FRET on Fiber' sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response.

  4. Computational Fluid Dynamics Modeling Three-Dimensional Unsteady Turbulent Flow and Excitation Force in Partial Admission Air Turbine

    Directory of Open Access Journals (Sweden)

    Yonghui Xie

    2013-01-01

    Full Text Available Air turbines are widely used to convert kinetic energy into power output in power engineering. The unsteady performance of air turbines with partial admission not only influences the aerodynamic performance and thermodynamic efficiency of turbine but also generates strong excitation force on blades to impair the turbine safely operating. Based on three-dimensional viscous compressible Navier-stokes equations, the present study employs RNG (Renormalization group k-ε turbulence model with finite volume discretization on air turbine with partial admission. Numerical models of four different admission rates with full annulus are built and analyzed via CFD (computational fluid dynamics modeling unsteady flows. Results indicate that the unsteady time-averaged isentropic efficiency is lower than the steady isentropic efficiency, and this difference rises as unsteady isentropic efficiency fluctuates stronger when the admission rate is reduced. The rotor axial and tangential forces with time are provided for all four admission rates. The low frequency excitation forces generated by partial admission are extraordinarily higher than the high frequency excitation forces by stator wakes.

  5. Partial Oxidation Gas Turbine for Power and Hydrogen Co-Production from Coal-Derived Fuel in Industrial Applications

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Rabovitser

    2009-06-30

    The report presents a feasibility study of a new type of gas turbine. A partial oxidation gas turbine (POGT) shows potential for really high efficiency power generation and ultra low emissions. There are two main features that distinguish a POGT from a conventional gas turbine. These are associated with the design arrangement and the thermodynamic processes used in operation. A primary design difference of the POGT is utilization of a non?catalytic partial oxidation reactor (POR) in place of a conventional combustor. Another important distinction is that a much smaller compressor is required, one that typically supplies less than half of the air flow required in a conventional gas turbine. From an operational and thermodynamic point of view a key distinguishing feature is that the working fluid, fuel gas provided by the OR, has a much higher specific heat than lean combustion products and more energy per unit mass of fluid can be extracted by the POGT expander than in the conventional systems. The POGT exhaust stream contains unreacted fuel that can be combusted in different bottoming ycle or used as syngas for hydrogen or other chemicals production. POGT studies include feasibility design for conversion a conventional turbine to POGT duty, and system analyses of POGT based units for production of power solely, and combined production of power and yngas/hydrogen for different applications. Retrofit design study was completed for three engines, SGT 800, SGT 400, and SGT 100, and includes: replacing the combustor with the POR, compressor downsizing for about 50% design flow rate, generator replacement with 60 90% ower output increase, and overall unit integration, and extensive testing. POGT performances for four turbines with power output up to 350 MW in POGT mode were calculated. With a POGT as the topping cycle for power generation systems, the power output from the POGT ould be increased up to 90% compared to conventional engine keeping hot section temperatures

  6. Nitric oxide in exhaled and aspirated nasal air as an objective measure of human response to indoor air pollution

    DEFF Research Database (Denmark)

    Kolarik, Barbara; Lagercrantz, L.; Sundell, Jan

    2009-01-01

    The concentration of nitric oxide (NO) in exhaled and aspirated nasal air was used to objectively assess human response to indoor air pollutants in a climate chamber exposure experiment. The concentration of NO was measured before exposure, after 2, and 4.5 h of exposure, using a chemiluminescence...... by the exposures. The results may indicate an association between polluted indoor air and subclinical inflammation.Measurement of nitric oxide in exhaled air is a possible objective marker of subclinical inflammation in healthy adults....... NO analyzer. Sixteen healthy female subjects were exposed to two indoor air pollutants and to a clean reference condition for 4.5 h. Subjective assessments of the environment were obtained by questionnaires. After exposure (4.5 h) to the two polluted conditions a small increase in NO concentration in exhaled...

  7. CO{sub 2} separation by calcium looping from full and partial fuel oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Sivalingam, Senthoorselvan

    2013-06-05

    This thesis work deals with the research and development of calcium looping process for CO{sub 2} separation from full and partial fuel oxidation based power generation systems. CO{sub 2} is the main greenhouse gas and undoubtedly a major contributor to the global warming. It is estimated that more than one third of the total anthropogenic CO{sub 2} emissions come from fossil fuel based heat and power generation. Moreover, fossil fuels are unlikely to be phased out rapidly, since developing alternative energy sources not only take time but also require huge investments and infrastructure. An alternative way to reduce emissions in a medium term is to capture the CO{sub 2} from fossil fueled power plants and store it away from the atmosphere. This process system combining a bunch of technologies is called carbon capture and storage (CCS). CO{sub 2} capture is an important and costly part of CCS and an array of technologies is considered for this. Calcium looping (CaL) is one of such and seems to offer effective and efficient CO{sub 2} separation from fuel oxidation processes. CaL process involves separation of CO{sub 2} at high temperatures (600-700 C) by calcium sorbents (CaO). CO{sub 2} reacts with CaO in a carbonation process and produces CaCO{sub 3}. In a subsequent thermal regeneration (>850 C) called calcination, the CO{sub 2} is released from CaCO{sub 3}. By alternating carbonations and calcinations over multiple cycles, CO{sub 2} is separated from a gas stream. Moreover, the CaL is realised in industrial scale with dual fluidised bed reactors for CO{sub 2} capture (the carbonator) and sorbent regeneration (the calciner). As a process in the development, research is still required in many aspects from thermodynamic modeling to experimental studies. Research works have been carried out in process simulations, sorbent reactivity and optimisation studies in a controlled reactor environment and process parametric studies in a semi-pilot scale CaL test facility

  8. CO2 separation by calcium looping from full and partial fuel oxidation processes

    International Nuclear Information System (INIS)

    Sivalingam, Senthoorselvan

    2013-01-01

    This thesis work deals with the research and development of calcium looping process for CO 2 separation from full and partial fuel oxidation based power generation systems. CO 2 is the main greenhouse gas and undoubtedly a major contributor to the global warming. It is estimated that more than one third of the total anthropogenic CO 2 emissions come from fossil fuel based heat and power generation. Moreover, fossil fuels are unlikely to be phased out rapidly, since developing alternative energy sources not only take time but also require huge investments and infrastructure. An alternative way to reduce emissions in a medium term is to capture the CO 2 from fossil fueled power plants and store it away from the atmosphere. This process system combining a bunch of technologies is called carbon capture and storage (CCS). CO 2 capture is an important and costly part of CCS and an array of technologies is considered for this. Calcium looping (CaL) is one of such and seems to offer effective and efficient CO 2 separation from fuel oxidation processes. CaL process involves separation of CO 2 at high temperatures (600-700 C) by calcium sorbents (CaO). CO 2 reacts with CaO in a carbonation process and produces CaCO 3 . In a subsequent thermal regeneration (>850 C) called calcination, the CO 2 is released from CaCO 3 . By alternating carbonations and calcinations over multiple cycles, CO 2 is separated from a gas stream. Moreover, the CaL is realised in industrial scale with dual fluidised bed reactors for CO 2 capture (the carbonator) and sorbent regeneration (the calciner). As a process in the development, research is still required in many aspects from thermodynamic modeling to experimental studies. Research works have been carried out in process simulations, sorbent reactivity and optimisation studies in a controlled reactor environment and process parametric studies in a semi-pilot scale CaL test facility. ASPEN Plus power plant simulations integrating the CaL based CO 2

  9. Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler

    Directory of Open Access Journals (Sweden)

    Jun-Xia Zhang

    2016-03-01

    Full Text Available Because the air-staged combustion technology is one of the key technologies with low investment running costs and high emission reduction efficiency for the pulverized boiler, it is important to reveal the chemical reaction kinetics mechanism for developing various technologies of nitrogen oxide reduction emissions. At the present work, a three-dimensional mesh model of the large-scale four corner tangentially fired boiler furnace is established with the GAMBIT pre-processing of the FLUENT software. The partial turbulent premixed and diffusion flame was simulated for the air-staged combustion processing. Parameters distributions for the air-staged and no the air-staged were obtained, including in-furnace flow field, temperature field and nitrogen oxide concentration field. The results show that the air-staged has more regular velocity field, higher velocity of flue gas, higher turbulence intensity and more uniform temperature of flue gas. In addition, a lower negative pressure zone and lower O2 concentration zone is formed in the main combustion zone, which is conducive to the NO of fuel type reduced to N2, enhanced the effect of NOx reduction. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th November 2015; Revised: 14th January 2016; Accepted: 16th January 2016  How to Cite: Zhang, J.X., Zhang, J.F. (2016. Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 100-108. (doi:10.9767/bcrec.11.1.431.100-108 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.431.100-108

  10. Design Fabrication And Partial-Analysis Of A 2-Wheeler Prototype That Runs On Compressed Air

    OpenAIRE

    P Vinay; Srivatsa G R; Venkatesh Datta; Dinesh Kumar A; Ramesha N; Dr. H K Govindaraju

    2015-01-01

    Abstract The primary objective of the project is to create a prototype of a purely air powered motorcycle by retrofitting its internal combustion engine to run on compressed air. Firstly the conventional spark plug was replaced with a solenoid valve. The solenoid valve was initially actuated using a reed switch and magnet duo but then later replaced with an optical crank position sensor circuit due to reasons that include lack of control over the amount of air injected during each stroke and ...

  11. Cladding oxidation during air ingress. Part II: Synthesis of modelling results

    International Nuclear Information System (INIS)

    Beuzet, E.; Haurais, F.; Bals, C.; Coindreau, O.; Fernandez-Moguel, L.; Vasiliev, A.; Park, S.

    2016-01-01

    Highlights: • A state-of-the-art for air oxidation modelling in the frame of severe accident is done. • Air oxidation models from main severe accident codes are detailed. • Simulations from main severe accident codes are compared against experimental results. • Perspectives in terms of need for further model development and experiments are given. - Abstract: Air ingress is a potential risk in some low probable situations of severe accidents in a nuclear power plant. Air is a highly oxidizing atmosphere that can lead to an enhanced Zr-based cladding oxidation and core degradation affecting the release of fission products. This is particularly true speaking about ruthenium release, due to its high radiotoxicity and its ability to form highly volatile oxides in a significant manner in presence of air. The oxygen affinity is decreasing from the Zircaloy cladding, fuel and ruthenium inclusions. It is consequently of great need to understand the phenomena governing cladding oxidation by air as a prerequisite for the source term issues in such scenarios. In the past years, many works have been done on cladding oxidation by air under severe accident conditions. This paper with in addition the paper “Cladding oxidation during air ingress – Part I: Synthesis of experimental results” of this journal issue aim at assessing the state of the art on this phenomenon. In this paper, the modelling of air ingress phenomena in the main severe accident codes (ASTEC, ATHLET-CD, MAAP, MELCOR, RELAP/SCDAPSIM, SOCRAT) is described in details, as well as the validation against the integral experiments QUENCH-10, QUENCH-16 and PARAMETER-SF4. A full review of cladding oxidation by air is thus established.

  12. Oxidation parameters of nuclear graphite for HTGR air-ingress

    International Nuclear Information System (INIS)

    Kim, E.S.; No, H.C.

    2004-01-01

    In order to investigate chemical behaviors of the graphite during an air-ingress accident in HTGR, the kinetic tests on nuclear graphite IG-110 were performed in chemical reaction dominant regime. In the present experiment, inlet gas flow rate ranged between 8 and 18 SLPM, graphite temperatures and oxygen mole fraction ranged from 540 to 630degC and from 3 to 30% respectively. The test section was made of a quartz tube having 75 mm diameter and 750 mm length and the test specimen machined to the size of 21 mm diameter and 30 mm length was supported at the center of it by the alumina rod. The 15 kW induction heater was installed around the outside of test section to heat the specimen and its temperature was measured by 2 infrared thermometers. The oxidation rate was calculated from the gas concentration analysis between inlet and outlet using NDIR (non-dispersive infrared) gas analyzer. As a result the activation energy (Ea) and the order of reaction (n) were determined within 95% confidence level and the qualitative characteristics of the two parameters were also widely investigated by experimental and analytical methods. (author)

  13. Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

    International Nuclear Information System (INIS)

    Li Ning; Descorme, Claude; Besson, Michele

    2007-01-01

    A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.% Ru/ZrO 2 . 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt.% Ru/ZrO 2 is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393 K) and lower total pressure (3 MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect

  14. Oxidation mechanism of Fe–16Cr alloy as SOFC interconnect in dry/wet air

    International Nuclear Information System (INIS)

    Chen, Zhi-Yuan; Wang, Li-Jun; Li, Fu-Shen; Chou, Kuo-Chih

    2013-01-01

    Highlights: •A special thermodynamic description corresponding to the kinetics was applied. •We reported the relationships of degradation time with temperature and moisture. •”Turning time” in the Fe–16Cr alloy oxidation kinetic model was given. •The oxidation mechanism of Fe–16Cr alloy in the wet air was discussed. -- Abstract: Experimental study on the oxidation corrosions of Fe–16Cr alloy was carried out at 800–1100 °C under dry/wet air conditions. Faster oxidation rate was observed at higher temperature and water vapor content. The degradation time t d between two stages in oxidation process showed an exponential relationship with elevating corrosion temperature in dry air, and a linear relationship with the water content in the case of water vapor introduced to the system. The mechanism of oxidation corrosions of Fe–16Cr alloy was suggested by the Real Physical Picture (RPP) model. It was found that the break-away oxidation in stage II was controlled by diffusion at initial both in dry and wet air, then became linear with the exposure time, which implied that the oxidation rate was then controlled by chemical reaction of the interface between the metal and the oxidized scale. Moreover, the effect of water in the oxidation process is not only to supply more oxygen into system, but also to modify the structures of oxide scale due to the existence of hydrogen atom, which results in the accelerated corrosions

  15. On the formation of nitrogen oxides during the combustion of partially pre-vaporized droplets

    Energy Technology Data Exchange (ETDEWEB)

    Moesl, Klaus Georg

    2012-12-12

    This study contributes to the topic of nitrogen oxide (NO{sub x}) formation at the level of single droplet and droplet array combustion. The influence of the degree of droplet vaporization and the influence of ambient conditions on NO{sub x} emissions are studied in detail by experiments as well as by numerical simulations. Consequently, this study illustrates correlations and dependencies of the most relevant parameters with respect to the formation of NO{sub x}. It merges the fields of droplet pre-vaporization, ignition, combustion, and exhaust gas formation, including a sophisticated approach to NO{sub x} determination. Even though the study was conducted in order to help understand the fundamental process of burning idealized droplets, the processes in spray combustion have also been taken into consideration within its scope. The portability of results obtained from those idealized droplet burning regimes is evaluated for real applications. Thus, this study may also help to derive design recommendations for liquid-fueled combustion devices. While the experimental part focuses on droplet array combustion, the numerical part highlights spherically symmetric single droplet combustion. By performing experiments in a microgravity environment, quasi-spherical conditions were facilitated for droplet burning, and comparability was provided for the experimental and numerical results. A novelty of the numerical part is the investigation of mechanisms of NO{sub x} formation under technically relevant conditions. This includes partial pre-vaporization of the droplets as well as droplet combustion in a hot exhaust gas environment, such as an aero-engine. The results show that the trade-off between ambient temperature and available oxygen determines the NO{sub x} formation of droplets burning in hot exhaust gas. If the ambient temperature is high and there is still sufficient oxygen for full oxidation of the fuel provided by the droplet, the maximum of NOx formation is

  16. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Science.gov (United States)

    2010-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2 NAAQS...

  17. Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor.

    Science.gov (United States)

    Harris, Eliza; Joss, Adriano; Emmenegger, Lukas; Kipf, Marco; Wolf, Benjamin; Mohn, Joachim; Wunderlin, Pascal

    2015-10-15

    Nitrous oxide (N2O) production pathways in a single stage, continuously fed partial nitritation-anammox reactor were investigated using online isotopic analysis of offgas N2O with quantum cascade laser absorption spectroscopy (QCLAS). N2O emissions increased when reactor operating conditions were not optimal, for example, high dissolved oxygen concentration. SP measurements indicated that the increase in N2O was due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor. The results of this study confirm that process control via online N2O monitoring is an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. Under normal operating conditions, the N2O isotopic site preference (SP) was much higher than expected - up to 40‰ - which could not be explained within the current understanding of N2O production pathways. Various targeted experiments were conducted to investigate the characteristics of N2O formation in the reactor. The high SP measurements during both normal operating and experimental conditions could potentially be explained by a number of hypotheses: i) unexpectedly strong heterotrophic N2O reduction, ii) unknown inorganic or anammox-associated N2O production pathway, iii) previous underestimation of SP fractionation during N2O production from NH2OH, or strong variations in SP from this pathway depending on reactor conditions. The second hypothesis - an unknown or incompletely characterised production pathway - was most consistent with results, however the other possibilities cannot be discounted. Further experiments are needed to distinguish between these hypotheses and fully resolve N2O production pathways in PN-anammox systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Optimization geometries of a vortex gliding-arc reactor for partial oxidation of methane

    International Nuclear Information System (INIS)

    Guofeng, Xu; Xinwei, Ding

    2012-01-01

    The effects of the geometry of gliding-arc reactor – such as distance between the electrodes, outlet diameter, and inlet position – on the reactor characteristics (methane conversion, hydrogen yield, and energy efficiency) have not been fully investigated. In this paper, AC gliding-arc reactors including the vortex flow configuration are designed to produce hydrogen from the methane by partial oxidation. The influence of vortex flow configuration on the reactor characteristics is also studied by varying the inlet position. When the inlet of the gliding-arc reactor is positioned close to the outlet, reverse vortex flow reactor (RVFR), the maximum energy efficiency reaches 50% and the yields of hydrogen and carbon monoxide are 40% and 65%, respectively. As the distance between electrodes increases from 5 mm to 15 mm, both hydrogen yield and energy efficiency increase approximately 10% for the RVFR. The energy efficiency and hydrogen yield are highest when the ratio of the outlet diameter to the inner diameter is 0.5 for the RVFR. Experimental results indicate that the flow field in the plasma reactor has an important influence on the reactor performance. Furthermore, hydrogen production increases as the number of feed gas flows in contact with the plasma zone increases. -- Highlights: ► Gliding-arc reactors were designed to produce hydrogen for studying the characteristics of the vortex flow reactor. ► Hydrogen yield of reverse vortex flow reactor was 10% higher than that of forward vortex flow reactor. ► Maximum energy efficiency was 50% for reverse vortex flow reactor. ► If discharge power was supplied to the reactors, the reactor performance increased with increasing distance between electrodes. ► Optimum ratio of the outlet and inner diameter was 1/2.

  19. Effects of dissolved oxygen and pH on nitrous oxide production rates in autotrophic partial nitrification granules.

    Science.gov (United States)

    Rathnayake, Rathnayake M L D; Oshiki, Mamoru; Ishii, Satoshi; Segawa, Takahiro; Satoh, Hisashi; Okabe, Satoshi

    2015-12-01

    The effects of dissolved oxygen (DO) and pH on nitrous oxide (N2O) production rates and pathways in autotrophic partial nitrification (PN) granules were investigated at the granular level. N2O was primarily produced by betaproteobacterial ammonia-oxidizing bacteria, mainly Nitrosomonas europaea, in the oxic surface layer (production increased with increasing bulk DO concentration owing to activation of the ammonia (i.e., hydroxylamine) oxidation in this layer. The highest N2O emissions were observed at pH 7.5, although the ammonia oxidation rate was unchanged between pH 6.5 and 8.5. Overall, the results of this study suggest that in situ analyses of PN granules are essential to gaining insight into N2O emission mechanisms in a granule. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Compressed air as a source of inhaled oxidants in intensive care units.

    Science.gov (United States)

    Thibeault, D W; Rezaiekhaligh, M H; Ekekezie, I; Truog, W E

    1999-01-01

    Exhaled gas from mechanically ventilated preterm infants was found to have similar oxidant concentrations, regardless of lung disease, leading to the hypothesis that wall outlet gases were an oxidant source. Oxidants in compressed room air and oxygen from wall outlets were assessed in three hospitals. Samples were collected by flowing wall outlet gas through a heated humidifier and an ice-packed condenser. Nitric oxide (NO) was measured in intensive care room air and in compressed air with and without a charcoal filter using a Sievers NOA280 nitric oxide analyzer (Boulder, CO). Oxidants were measured by spectrophotometry and expressed as nMol equivalents of H2O2/mL. The quantity of oxidant was also expressed as amount of Vitamin C (nMol/mL) added until the oxidant was nondetectable. This quantity of Vitamin C was also expressed in Trolox Equivalent Antioxidant Capacity (TEAC) units (mMol/L). Free and total chlorine were measured with a Chlorine Photometer. Oxidants were not found in compressed oxygen and were only found in compressed air when the compression method used tap water. At a compressed room air gas flow of 1.5 L/min, the total volume of condensate was 20.2 +/- 1 mL/hr. The oxidant concentration was 1.52 +/- 0.09 nMol/mL equivalents of H2O2/mL of sample and 30.8 +/- 1.2 nMol/hr; 17.9% of that found in tap water. Oxidant reduction required 2.05 +/-0.12 nMol/mL vitamin C, (1.78 +/- 0.1 x 10(-3) TEAC units). Free and total chlorine in tap water were 0.3 +/- 0.02 mg/mL and 2.9 +/- 0.002 mg/mL, respectively. Outlet gas contained 0.4 +/- 0.06 mg/mL and 0.07 + 0.01 mg/mL total and free chlorine, respectively; both 14% of tap water. When a charcoal filter was installed in the hospital with oxidants in compressed air, oxidants were completely removed. Nursery room air contained 12.4 +/- 0.5 ppb NO; compressed wall air without a charcoal filter, 8.1 +/- 0.1 ppb and compressed air with a charcoal filter 12.5 +/- 0.5 ppb. A charcoal filter does not remove NO. (Table

  1. Use of partial order in environmental pollution studies demonstrated by urban BTEX air pollution in 20 major cities worldwide.

    Science.gov (United States)

    Carlsen, Lars; Bruggemann, Rainer; Kenessov, Bulat

    2018-01-01

    Urban air pollution with benzene, toluene, ethyl benzene and xylenes (BTEX) is a common phenomenon in major cities where the pollution mainly originates from traffic as well as from residential heating. An attempt to rank cities according to their BTEX air pollution is not necessarily straight forward as we are faced with several individual pollutants simultaneously. A typical procedure is based on aggregation of data for the single compounds, a process that not only hides important information but is also subject to compensation effects. The present study applies a series of partial ordering tools to circumvent the aggregation. Based on partial ordering, most important indicators are disclosed, and an average ranking of the cities included in the study is derived. Since air pollution measurements are often subject to significant uncertainties, special attention has been given to the possible effect of uncertainty and/or data noise. Finally, the effect of introducing weight regimes is studied. In a concluding section the gross national income per person (GNI) is brought into play, demonstrating a positive correlation between BTEX air pollution and GNI. The results are discussed in terms of the ability/willingness to combat air pollution in the cities studied. The present study focuses on Almaty, the largest city in Kazakhstan and compares the data from Almaty to another 19 major cities around the world. It is found that the benzene for Almaty appears peculiar high. Overall Almaty appears ranked as the 8th most BTEX polluted city among the 20 cities included in the study. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Design Fabrication And Partial-Analysis Of A 2-Wheeler Prototype That Runs On Compressed Air

    Directory of Open Access Journals (Sweden)

    P Vinay

    2015-08-01

    Full Text Available Abstract The primary objective of the project is to create a prototype of a purely air powered motorcycle by retrofitting its internal combustion engine to run on compressed air. Firstly the conventional spark plug was replaced with a solenoid valve. The solenoid valve was initially actuated using a reed switch and magnet duo but then later replaced with an optical crank position sensor circuit due to reasons that include lack of control over the amount of air injected during each stroke and also for more precise control over the opening and closing of the valve. The torque brake power indicated power air consumption rate of the engine under load are calculated. Separate mounts for the modified engine and the cylindrical storage unit are designed and analysed using Catia v4. Also possible ways of future scope of the prototype are mentioned.

  3. Effect of the pre-transient oxide on Zy-4 cladding degradation in air and air+steam atmospheres

    International Nuclear Information System (INIS)

    Duriez, C.; Guerain, M.; Lacote, P.; Mermoux, M.

    2015-01-01

    High temperature reactivity in air of Zr based alloys has been mostly investigated with initially bare cladding materials. In this study, attention is paid to the influence of a low temperature pre-oxidation scale aiming to simulate the corrosion scale existing on spent fuel. Different out of pile pre-oxidation methods, inducing significant variation in the pre-oxides microstructure, are compared. The reaction kinetics in air and in mixed air + steam atmospheres, investigated in the 700-950 C. degrees temperature range by thermogravimetry (TGA), shows that a pre-oxide scale formed at low temperature has a protective effect at high temperature by significantly delaying occurrence of the kinetic acceleration, which however still occurs. Efficiency of this protective effect appears to depend on the type of pre-oxide. To better understand the exact role of the pre-oxide, oxygen transport through the pre-oxide has been investigated using the 18 O tracer technique. 18 O distribution maps have been obtained by micro-Raman imaging, which has proved to offer interesting capabilities for that purpose. Results obtained with a 30 μm pre-oxide scale formed at 425 C. degrees in oxygen suggest that, at 850 C. degrees, only the inner part of the scale acts as a barrier against oxidation while the outermost part of the scale (5 to 15 μm in thickness) seems to be permeable to gaseous oxygen. The use of the 18 O isotope tracer technique associated with micro-Raman mapping of the scales is demonstrated to be a powerful method to investigate the transport properties of the scales and will help to gain understanding of the kinetic differences between the different pre-oxides

  4. The partial pressure of oxygen affects biomarkers of oxidative stress in cultured rainbow trout (Oncorhynchus mykiss) hepatocytes.

    Science.gov (United States)

    Finne, E F; Olsvik, P A; Berntssen, M H G; Hylland, K; Tollefsen, K E

    2008-09-01

    Oxidative stress, the imbalance between production of reactive oxygen species and the cellular detoxification of these reactive compounds, is believed to be involved in the pathology of various diseases. Several biomarkers for oxidative stress have been proposed to serve as tools in toxicological and ecotoxicological research. Not only may exposure to various pro-oxidants create conditions of cellular oxidative stress, but hyperoxic conditions may also increase the production of reactive oxygen species. The objective of the current study was to determine the extent to which differences in oxygen partial pressure would affect biomarkers of oxidative stress in a primary culture of hepatocytes from rainbow trout (Oncorhynchus mykiss). Membrane integrity, metabolic activity, levels of total and oxidized glutathione (tGSH/GSSG) was determined, as well as mRNA expression levels of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), gamma-glutamyl-cystein synthetase (GCS) and thioredoxin (TRX). The results show that different biomarkers of oxidative stress are affected when the cell culture is exposed to atmospheric oxygen, and that changes such as increased GSSG content and induction of GSSG-R and GSH-Px can be reduced by culturing the cells under lower oxygen tension. Oxygen tension may thus influence results of in vitro based cell research and is particularly important when assessing parameters in the antioxidant defence system. Further research is needed to establish the magnitude of this effect in different cellular systems.

  5. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING/FEASIBILTY SUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER.M; HONG,G

    2005-01-01

    General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The key potential advantage of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reacting and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carried out at the University of Hawaii at Manoa (UHM), as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an activated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low-value, dirty feed materials. The Phase I results indicate that a practical

  6. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  7. Effect of air-excess on blends of RON70 partially premixed combustion

    NARCIS (Netherlands)

    Wang, S.; Bakker, P.C.; Somers, L.M.T.; de Goey, L.P.H.

    Partially Premixed Combustion (PPC) is a combustion concept that aims to provide combustion with low smoke and NOx emissions and a high thermal efficiency. Extending the ignition delay to enhance premixing, avoiding spray-driven combustion, and controlling temperature at an optimum level through use

  8. Catalytic wet air oxidation of aniline with nanocasted Mn-Ce-oxide catalyst.

    Science.gov (United States)

    Levi, R; Milman, M; Landau, M V; Brenner, A; Herskowitz, M

    2008-07-15

    The catalytic wet air oxidation of aqueous solution containing 1000 ppm aniline was conducted in a trickle-bed reactor packed with a novel nanocasted Mn-Ce-oxide catalyst (surface area of 300 m2/g) prepared using SBA-15 silica as a hard template. A range of liquid hourly space velocities (5-20 h(-1)) and temperatures (110-140 degrees C) at 10 bar of oxygen were tested. The experiments were conducted to provide the intrinsic performance of the catalysts. Complete aniline conversion, 90% TOC conversion, and 80% nitrogen mineralization were achieved at 140 degrees C and 5 h(-1). Blank experiments yielded relatively low homogeneous aniline (<35%) and negligible TOC conversions. Fast deactivation of the catalysts was experienced due to leaching caused by complexation with aniline. Acidification of the solution with HCI (molar HCI to aniline ratio of 1.2) was necessary to avoid colloidization and leaching of the nanoparticulate catalyst components. The catalyst displayed stable performance for over 200 h on stream.

  9. Pressurized solid oxide fuel cell integral air accumular containment

    Science.gov (United States)

    Gillett, James E.; Zafred, Paolo R.; Basel, Richard A.

    2004-02-10

    A fuel cell generator apparatus contains at least one fuel cell subassembly module in a module housing, where the housing is surrounded by a pressure vessel such that there is an air accumulator space, where the apparatus is associated with an air compressor of a turbine/generator/air compressor system, where pressurized air from the compressor passes into the space and occupies the space and then flows to the fuel cells in the subassembly module, where the air accumulation space provides an accumulator to control any unreacted fuel gas that might flow from the module.

  10. Inkjet Impregnation for Tailoring Air Electrode Microstructure to Improve Solid Oxide Cells Performance

    KAUST Repository

    Da’ as, Eman H.

    2015-01-01

    The urge to lower the operating temperature of solid oxide cells (SOCs) to the intermediate ranges between 500-700°C motivated the research into impregnation processes, which offer highly efficient SOC air electrodes at low operating temperatures

  11. Controls of nitrite oxidation in ammonia-removing biological air filters

    DEFF Research Database (Denmark)

    Juhler, Susanne; Ottosen, Lars Ditlev Mørck; Nielsen, Lars Peter

    2008-01-01

    in accumulation of nitrate rather than nitrite and a significant decline in pH. As a consequence, ammonia is removed more efficiently, but heterotrophic oxidation of odorous compounds might be inhibited.  To identify the controlling mechanisms of nitrite oxidation, full-scale biological air filters were...... activity resulting in a lowered pH and thus a decreased FA concentration, promoting further growth of NOB. Yet, in some cases a situation with a nitrate-to-nitrite ratio of 1 and moderate pH remained stable even under varying air load and water supply, suggesting that additional mechanisms were involved......In biological air filters ammonia is removed due to the action of Ammonia Oxidizing Bacteria (AOB) resulting in nitrite accumulation exceeding 100 mM. Among filters treating exhaust air from pig facilities successful establishment of Nitrite Oxidizing Bacteria (NOB) sometimes occurs, resulting...

  12. Properties of polycrystalline indium oxide in open air and in vacuum

    International Nuclear Information System (INIS)

    Solov'eva, A.E.; Zhdanov, V.A.; Markov, V.L.; Shvangiradze, R.R.

    1982-01-01

    Properties of polycrystalline indium oxide according to annealing temperature in open air and in vacuum are investigated. It is established that the indium oxide begins to change its chemical composition during the annealing in the open air from 1200 deg C, and in the vacuum - form 800 deg C. During the annealing of the samples in ths open air in the temperature range of 1200-1450 deg C the lattice of the indium oxide loses probably, only oxygen; this process is accompanied by change of the samples color, electrophysical properties, lattice parameter density. Cation sublattice is disturbed in the vacuum beginning from 900 deg C, which is accompanied by destruction of the color centers. X-ray density and the activation energy of the reduction accounting the formation of the color centers are calculated on the base of the X-ray data and the deviation from stoichiometry of the indium oxide depending on the annealing temperature in the open air

  13. Dry air effects on the copper oxides sensitive layers formation for ethanol vapor detection

    International Nuclear Information System (INIS)

    Labidi, A.; Bejaoui, A.; Ouali, H.; Akkari, F. Chaffar; Hajjaji, A.; Gaidi, M.; Kanzari, M.; Bessais, B.; Maaref, M.

    2011-01-01

    The copper oxide films have been deposited by thermal evaporation and annealed under ambient air and dry air respectively, at different temperatures. The structural characteristics of the films were investigated by X-ray diffraction. They showed the presences of two hydroxy-carbonate minerals of copper for annealing temperatures below 250 deg. C. Above this temperature the conductivity measurements during the annealing process, show a transition phase from metallic copper to copper oxides. The copper oxides sensitivity toward ethanol were performed using conductivity measurements at the working temperature of 200 deg. C. A decrease of conductivity was observed under ethanol vapor, showing the p-type semi-conducting characters of obtained copper oxide films. It was found that the sensing properties of copper oxide toward ethanol depend mainly on the annealing conditions. The best responses were obtained with copper layers annealed under dry air.

  14. Dry air effects on the copper oxides sensitive layers formation for ethanol vapor detection

    Energy Technology Data Exchange (ETDEWEB)

    Labidi, A., E-mail: Ahmed_laabidi@yahoo.fr [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia); Bejaoui, A.; Ouali, H. [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia); Akkari, F. Chaffar [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs, ENIT, Universite de Tunis el Manar, BP 37, Le belvedere 1002, Tunis (Tunisia); Hajjaji, A.; Gaidi, M. [Laboratoire de Photovoltaique, Centre de Recherches et de technologies de l' energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia); Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs, ENIT, Universite de Tunis el Manar, BP 37, Le belvedere 1002, Tunis (Tunisia); Bessais, B. [Laboratoire de Photovoltaique, Centre de Recherches et de technologies de l' energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia); Maaref, M. [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia)

    2011-09-15

    The copper oxide films have been deposited by thermal evaporation and annealed under ambient air and dry air respectively, at different temperatures. The structural characteristics of the films were investigated by X-ray diffraction. They showed the presences of two hydroxy-carbonate minerals of copper for annealing temperatures below 250 deg. C. Above this temperature the conductivity measurements during the annealing process, show a transition phase from metallic copper to copper oxides. The copper oxides sensitivity toward ethanol were performed using conductivity measurements at the working temperature of 200 deg. C. A decrease of conductivity was observed under ethanol vapor, showing the p-type semi-conducting characters of obtained copper oxide films. It was found that the sensing properties of copper oxide toward ethanol depend mainly on the annealing conditions. The best responses were obtained with copper layers annealed under dry air.

  15. Investigation of effect of air flow rate on Zircaloy-4 oxidation kinetics and breakaway phenomenon in air at 850 .deg. C

    International Nuclear Information System (INIS)

    Maeng, Yunhwan; Lee, Jaeyoung; Park, Sanggil

    2016-01-01

    This paper analyzed an effect of flow rate on oxidation kinetics of Zircaloy-4 in air at 850 .deg. C. In case of the oxidation of Zircaloy-4 in air at 850 .deg. C, acceleration of oxidation kinetics from parabolic to linear (breakaway phenomenon) occurs. Oxidation and breakaway kinetics of the Zircaloy-4 in air was experimentally studied by changing a flow rate of argon/air mixture. Tests were conducted at 850 .deg. C under constant ratio of argon and air. The effects of flow rate on the oxidation and breakaway kinetics was observed. This paper is based on a revised and considerably extended presentation given at the 21 st International Quench Workshop. The effects of flow conditions on the oxidation kinetics of Zircaloy-4 samples were explained with residence time and percent flow efficiency. In addition, several issues were observed from this study, interdiffusion at breakaway and deformation of oxide structure by breakaway phenomenon

  16. 77 FR 75703 - Partial Approval and Disapproval of Air Quality Implementation Plans; Arizona; Regional Haze and...

    Science.gov (United States)

    2012-12-21

    ... 2.5 can also cause serious health effects and mortality in humans and contributes to environmental... Technical Support System (TSS) which provides an analysis of the causes of haze, and the levels of... determined by using air quality measurements to estimate light extinction and then transforming the value of...

  17. A low-temperature partial-oxidation-methanol micro reformer with high fuel conversion rate and hydrogen production yield

    International Nuclear Information System (INIS)

    Wang, Hsueh-Sheng; Huang, Kuo-Yang; Huang, Yuh-Jeen; Su, Yu-Chuan; Tseng, Fan-Gang

    2015-01-01

    Highlights: • A low-operating temperature of the POM-mode micro methanol reformer is obtained. • The effect of channel design on the performance is studied. • The effect of solid content and binder’ ratio on the performance is studied. • The centrifugal process is benefit for the modification of performance. • 98% of methanol conversion rate of the micro reformer can be obtained at 180 °C. - Abstract: A partial oxidation methanol micro reformer (POM-μReformer) with finger-shaped channels for low operating temperature and high conversing efficiency is proposed in this study. The micro reformer employs POM reaction for low temperature operation (less than 200 °C), exothermic reaction, and quick start-up, as well as air feeding capability; and the finger type reaction chambers for increasing catalyst loading as well as reaction area for performance enhancement. In this study, centrifugal technique was introduced to assist on the catalyst loading with high amount and uniform distribution. The solid content (S), binder’s ratio (B), and channel design (the ratio between channel’s length and width, R) were investigated in detail to optimize the design parameters. Scanning electron microscopy (SEM), gas chromatography (GC), and inductively coupled plasma-mass spectrometer (ICP-MS) were employed to analyze the performance of the POM-μReformer. The result depicted that the catalyst content and reactive area could be much improved at the optimized condition, and the conversion rate and hydrogen selectivity approached 97.9% and 97.4%, respectively, at a very low operating temperature of 180 °C with scarce or no binder in catalyst. The POM-μReformer can supply hydrogen to fuel cells by generating 2.23 J/min for 80% H 2 utilization and 60% fuel cell efficiency at 2 ml/min of supplied reactant gas, including methanol, oxygen and argon at a mixing ratio of 12.2%, 6.1% and 81.7%, respectively

  18. Nitric oxide in exhaled and aspirated nasal air as an objective measure of human response to isopropanol oxidation products and pthtalate esters in indoor air

    DEFF Research Database (Denmark)

    Lagercrantz, Love Per; Famula, Basia; Sundell, Jan

    2005-01-01

    The use of Nitric Oxide (NO) concentration in exhaled and aspirated nasal air to assess human response to indoor air pollution was tested in a climate chamber exposure experiment. The concentration of NO was measured using a chemiluminescence NO analyser. Sixteen healthy female subjects were...... exposed to 2 commonly occurring indoor air pollutants and to a clean reference condition for 4.5 hours. Assessments of the environment were obtained using questionnaires. The polluted conditions were perceived as worse than the reference condition. After exposure to the two polluted conditions a small...... increase in NO concentration (+2.7% and +7.2%) in exhaled air was observed. After exposure to the reference condition the mean NO concentration was significantly reduced (-14.3%) compared to before exposure. NO in nasal air was unaffected by the exposures. The results indicate an association between...

  19. Indoor air purification using heterogeneous photocatalytic oxidation. Part I: Experimental study

    NARCIS (Netherlands)

    Yu, Q.; Brouwers, H.J.H.

    2009-01-01

    Heterogeneous photocatalytic oxidation (PCO) has shown to be a promising air purifying technology in outdoor conditions using TiO2 as photocatalyst activated with UV light. Also to indoor air quality more and more attention is paid because of the very important role it plays on human health, and it

  20. Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

    DEFF Research Database (Denmark)

    Sun, Yuexia; Fang, Lei; Wyon, David P.

    2005-01-01

    The experiment presented in this report was performed in a simulated aircraft cabin to evalu-ate the air cleaning effects of two air purification devices using Photocatalytic Oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjec-tive human assessments ...

  1. Indoor air purificaton using heterogeneous photocatalytic oxidation, Part 2: Kinetic study

    NARCIS (Netherlands)

    Yu, Q.; Ballari, M.; Brouwers, H.J.H.

    2010-01-01

    In part I to this article [1], the application of the heterogeneous photocatalytic oxidation (PCO) theory for the indoor air quality improvement was presented. With a modified TiO2 that can be activated by visible light as the photocatalyst coated on a special wall paper, and one typical indoor air

  2. 78 FR 47253 - Approval and Promulgation of Air Quality Implementation Plans; Maine; Oxides of Nitrogen...

    Science.gov (United States)

    2013-08-05

    ... Promulgation of Air Quality Implementation Plans; Maine; Oxides of Nitrogen Exemption and Ozone Transport... is proposing to approve Maine's October 13, 2012, request for an exemption from the nitrogen oxides... from Stephen D. Page, Director, OAQPS, dated January 14, 2005, entitled ``Guidance on Limiting Nitrogen...

  3. A novel partial SOI LDMOSFET with periodic buried oxide for breakdown voltage and self heating effect enhancement

    Science.gov (United States)

    Jamali Mahabadi, S. E.; Rajabi, Saba; Loiacono, Julian

    2015-09-01

    In this paper a partial silicon on insulator (PSOI) lateral double diffused metal oxide semiconductor field effect transistor (LDMOSFET) with periodic buried oxide layer (PBO) for enhancing breakdown voltage (BV) and self-heating effects (SHEs) is proposed for the first time. This new structure is called periodic buried oxide partial silicon on insulator (PBO-PSOI). In this structure, periodic small pieces of SiO2 were used as the buried oxide (BOX) layer in PSOI to modulate the electric field in the structure. It was demonstrated that the electric field is distributed more evenly by producing additional electric field peaks, which decrease the common peaks near the drain and gate junctions in the PBO-PSOI structure. Hence, the area underneath the electric field curve increases which leads to higher breakdown voltage. Also a p-type Si window was introduced in the source side to force the substrate to share the vertical voltage drop, leading to a higher vertical BV. Furthermore, the Si window under the source and those between periodic pieces of SiO2 create parallel conduction paths between the active layer and substrate thereby alleviating the SHEs. Simulations with the two dimensional ATLAS device simulator from the Silvaco suite of simulation tools show that the BV of PBO-PSOI is 100% higher than that of the conventional partial SOI (C-PSOI) structure. Furthermore the PBO-PSOI structure alleviates SHEs to a greater extent than its C-PSOI counterpart. The achieved drain current for the PBO-PSOI structure (100 μA), at drain-source voltage of VDS = 100 V and gate-source voltage of VGS = 25 V, is shown to be significantly larger than that in C-PSOI and fully depleted SOI (FD-SOI) structures (87 μA and 51 μA respectively). Drain current can be further improved at the expense of BV by increasing the doping of the drift region.

  4. Increased hydrazine during partial nitritation process in upflow air-lift reactor fed with supernatant of anaerobic digester effluent

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeongdong [University of Alberta, Alberta (Canada); Jung, Sokhee [Samsung SDS, Seoul (Korea, Republic of); Ahn, Young-Ho [Yeungnam University, Gyungsan (Korea, Republic of)

    2013-06-15

    The optimal balance of ammonium and nitrite is essential for successful operation of the subsequent anammox process. We conducted a partial nitritation experiment using an upflow air-lift reactor to provide operational parameters for achieving the optimal ratio of ammonium to nitrite, by feeding supernatant of anaerobic digester effluent, high-nitrogen containing rejection water. Semi-continuous operation results show that HRT should be set between 15 and 17 hours to achieve the optimum ration of 1.3 of NO{sub 2}-N/NH{sub 4}-N. In the UAR, nitritation was the dominant reaction due to high concentration of ammonia and low biodegradable organics. The influent contained low concentrations of hydroxylamine and hydrazine. However, hydrazine increased during partial nitritation by ⁓60-130% although there was no potential anammox activity in the reactor. The partial nitritation process successfully provided the ratio of nitrogen species for the anammox reaction, and relived the nitrite restraint on the anammox activity by increasing hydrazine concentration.

  5. Unintended inhalation of nitric oxide by contamination of compressed air: physiologic effects and interference with intended nitric oxide inhalation in acute lung injury.

    Science.gov (United States)

    Benzing, A; Loop, T; Mols, G; Geiger, K

    1999-10-01

    Compressed air from a hospital's central gas supply may contain nitric oxide as a result of air pollution. Inhaled nitric oxide may increase arterial oxygen tension and decrease pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. Therefore, the authors wanted to determine whether unintentional nitric oxide inhalation by contamination of compressed air influences arterial oxygen tension and pulmonary vascular resistance and interferes with the therapeutic use of nitric oxide. Nitric oxide concentrations in the compressed air of a university hospital were measured continuously by chemiluminescence during two periods (4 and 2 weeks). The effects of unintended nitric oxide inhalation on arterial oxygen tension (n = 15) and on pulmonary vascular resistance (n = 9) were measured in patients with acute lung injury and acute respiratory distress syndrome by changing the source of compressed air of the ventilator from the hospital's central gas supply to a nitric oxide-free gas tank containing compressed air. In five of these patients, the effects of an additional inhalation of 5 ppm nitric oxide were evaluated. During working days, compressed air of the hospital's central gas supply contained clinically effective nitric oxide concentrations (> 80 parts per billion) during 40% of the time. Change to gas tank-supplied nitric oxide-free compressed air decreased the arterial oxygen tension by 10% and increased pulmonary vascular resistance by 13%. The addition of 5 ppm nitric oxide had a minimal effect on arterial oxygen tension and pulmonary vascular resistance when added to hospital-supplied compressed air but improved both when added to tank-supplied compressed air. Unintended inhalation of nitric oxide increases arterial oxygen tension and decreases pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. The unintended nitric oxide inhalation interferes with the

  6. Potential hydrogen and oxygen partial pressures in legacy plutonium oxide packages at Oak Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Veirs, Douglas K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-07

    An approach to estimate the maximum hydrogen and oxygen partial pressures within sealed containers is described and applied to a set of packages containing high-purity plutonium dioxide. The approach uses experimentally determined maximum hydrogen and oxygen partial pressures and scales the experimentally determined pressures to the relevant packaged material properties. The important material properties are the specific wattage and specific surface area (SSA). Important results from the experimental determination of maximum partial pressures are (1) the ratio of hydrogen to oxygen is stoichiometric, and (2) the maximum pressures increase with increasing initial rates of production. The material properties that influence the rates are the material specific wattage and the SSA. The unusual properties of these materials, high specific wattage and high SSA, result in higher predicted maximum pressures than typical plutonium dioxide in storage. The pressures are well within the deflagration range for mixtures of hydrogen and oxygen.

  7. Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing

    International Nuclear Information System (INIS)

    Patil, R B; Puri, R K; Puri, V

    2008-01-01

    Bismuth oxide thin films of thickness 1000 A 0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The effect of vapour chopping and air exposure for 40 days on the intrinsic stress of bismuth oxide thin films has been studied. The vapour chopped films showed low (3.92 - 4.80 x 10 9 N/m 2 ) intrinsic stress than those of nonchopped bismuth oxide thin films (5.77 - 6.74 x 10 9 N/m 2 ). Intrinsic stress was found to increase due to air ageing. The effect of air ageing on the vapour chopped films was found low. The vapour chopped films showed higher packing density. Higher the packing density, lower the film will age. The process of chopping vapour flow creates films with less inhomogenety i.e. a low concentration of flaws and non-planar defects which results in lower intrinsic stress

  8. Evaluation of thermodynamic and kinetic stability of P-type transparent conducting oxide, SrCu2O2 under various oxygen partial pressures

    International Nuclear Information System (INIS)

    Sugimoto, Takayuki; Yanagawa, Atsumi; Hashimoto, Takuya

    2012-01-01

    Highlights: ▶ Thermodynamic and kinetic stabilities of SrCu 2 O 2 under various P(O 2 ) was estimated. ▶ The reaction rate for decomposition decreased with decreasing temperature and P(O 2 ). ▶ The activation energy for decomposition of SrCu 2 O 2 was estimated to be 66 kJ/mol. ▶ SrCu 2 O 2 showed less stability than those of other transparent p-type semiconductors. - Abstract: Kinetic stability of transparent p-type conducting oxide, SrCu 2 O 2 , has been evaluated by using X-ray diffraction measurement and thermogravimetry. It was revealed that SrCu 2 O 2 decomposed to mixture of CuO and Sr 14 Cu 24 O 41 in air at temperatures above 300 °C. The decomposition reaction rate can be successfully explained by kinetic model assuming first-order chemical reaction. The rate constant can be suppressed with decreasing temperature and oxygen partial pressure. The activation energy for decomposition reaction of SrCu 2 O 2 calculated from Arrhenius plot was 66 kJ/mol, which was lower than those of other transparent p-type semiconductors such as CuAlO 2 and CuGaO 2 . The low decomposition temperature and activation energy for decomposition indicate that chemical stability of SrCu 2 O 2 is far lower than those of other p-type conducting oxides.

  9. Oscillatory behaviour of catalytic properties, structure and temperature during the catalytic partial oxidation of methane on Pd/Al2O3

    DEFF Research Database (Denmark)

    Kimmerle, B.; Baiker, A.; Grunwaldt, Jan-Dierk

    2010-01-01

    Pd/Al2O3 catalysts showed an oscillatory behaviour during the catalytic partial oxidation (CPO) of methane, which was investigated simultaneously by IR-thermography, X-ray absorption spectroscopy, and online mass-spectrometry to correlate the temperature, state of the catalyst and catalytic...... to self-reduction leading to extinction of the process. The latter was the key driver for the oscillations and thus gave additional insight into the mechanism of partial methane oxidation....

  10. Carbon-coated magnetic palladium: applications in partial oxidation of alcohols and coupling reactions.

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; catalyst can be used for oxidation of alcohols, amination reaction and arylation of aryl halides (cross coupli...

  11. In situ photoemission spectroscopy using synchrotron radiation for O2 translational kinetic energy induced oxidation processes of partially-oxidized Si(001) surfaces

    International Nuclear Information System (INIS)

    Teraoka, Yuden; Yoshigoe, Akitaka

    2001-01-01

    The influence of translational kinetic energy of incident O 2 molecules for the passive oxidation process of partially-oxidized Si(001) surfaces has been studied by photoemission spectroscopy. The translational kinetic energy of O 2 molecules was controlled up to 3 eV by a supersonic seed beam technique using a high temperature nozzle. Two translational kinetic energy thresholds (1.0 eV and 2.6 eV) were found out in accordance with the first-principles calculation for the oxidation of clean surfaces. Si-2p photoemission spectra measured in representative translational kinetic energies revealed that the translational kinetic energy dependent oxidation of dimers and the second layer (subsurface) backbonds were caused by the direct dissociative chemisorption of O 2 molecules. Moreover, the difference in chemical bonds for oxygen atoms was found out to be as low and high binding energy components in O-1s photoemission spectra. Especially, the low binding energy component increased with increasing the translational kinetic energy that indicates the translational kinetic energy induced oxidation in backbonds. (author)

  12. Partial oxidation of dimethyl ether using the structured catalyst Rh/Al2O3/Al prepared through the anodic oxidation of aluminum.

    Science.gov (United States)

    Yu, B Y; Lee, K H; Kim, K; Byun, D J; Ha, H P; Byun, J Y

    2011-07-01

    The partial oxidation of dimethyl ether (DME) was investigated using the structured catalyst Rh/Al2O3/Al. The porous Al2O3 layer was synthesized on the aluminum plate through anodic oxidation in an oxalic-acid solution. It was observed that about 20 nm nanopores were well developed in the Al2O3 layer. The thickness of Al2O3 layer can be adjusted by controlling the anodizing time and current density. After pore-widening and hot-water treatment, the Al2O3/Al plate was calcined at 500 degrees C for 3 h. The obtained delta-Al2O3 had a specific surface area of 160 m2/g, making it fit to be used as a catalyst support. A microchannel reactor was designed and fabricated to evaluate the catalytic activity of Rh/Al2O3/Al in the partial oxidation of DME. The structured catalyst showed an 86% maximum hydrogen yield at 450 degrees C. On the other hand, the maximum syngas yield by a pack-bed-type catalyst could be attained by using a more than fivefold Rh amount compared to that used in the structured Rh/Al2O3/Al catalyst.

  13. Strategies for catalyst development: possibilities of the ``rational approach`` illustrated with partial oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, W.; Schedel-Niedrig, T.; Schloegl, R. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany). Abt. Oberflaechenphysik

    1998-12-31

    The paper discusses two petrochemical selective oxidation reactions namely the practised formation of styrene (STY) and the desired oxidative functionalisation of propane. The present knowledge about the mode of operation of oxide catalysts is critically considered. The dehydrogenation of ethylbenzene (EB) should be described by an oxidehydration with water acting as oxidant. The potential role of the coke formed during catalytic reaction as co-catalyst will be discussed. Selective oxidation is connected with the participation of lattice oxygen mechanism which transforms unselective gas phase oxygen into selective oxygen. The atomistic description of this process is still quite unclear as well as the electron structural properties of the activated oxygen atom. The Role of solid state acidity as compared to the role of lattice oxygen is much less well investigated modern multiphase-multielement oxide (MMO) catalysts. The rationale is that the significant efforts made to improve current MMO systems by chemical modifications can be very much more fruitful when in a first step the mode of action of a catalyst is clarified on the basis of suitable experiments. Such time-consuming experiments at the beginning of a campaign for catalyst improvement pay back their investment in later stages of the project when strategies of chemical development can be derived on grounds of understanding. (orig.)

  14. Respiratory symptoms, spirometry, and oxidant air pollution in nonsmoking adults

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, C.A.; Hudson, A.R.; Clauson, J.L.; Knelson, J.H.

    1972-01-01

    Comparison of 197 nonsmokers (Seventh Day Adventists) residing in the San Gabriel Valley (high oxidant) with 244 living in San Diego area (similar pollution but with lower oxidant) is discussed. Study was conducted in winter when differences between the two areas were negligible and thus when irreversible effects could be detected. Some unusual findings included: an unexpectedly low chronic bronchitis prevalence rate of 1.77% as compared with the general population, a greater prevalence of chronic bronchitis in women in both areas (not significant), and no effect of socio-economic status. Comparison of pulmonary function using VC, FEV, MEF, peak flow, time constant, and FVC showed no differences between the two groups. The annual mean oxidant level is about the same in both areas and may have influenced spirometric values more than oxidant peaks. Also, these tests may not have been sufficiently sensitive.

  15. Quantitative Analysis of Major Phytochemicals in Orthodox tea (Camellia sinensis), Oxidized under Compressed Air Environment.

    Science.gov (United States)

    Panda, Brajesh Kumar; Datta, Ashis Kumar

    2016-04-01

    This study describes major changes in phytochemical composition of orthodox tea (Camellia sinensis var. Assamica) oxidized under compressed air (CA). The experiments for oxidation were conducted under air pressure (101, 202, and 303 kPa) for 150 min. Relative change in the concentrations of caffeine, catechins, theaflavins (TF), and thearubigins (TR) were analyzed. Effect of CA pressure was found to be nonsignificant in regulating caffeine concentration during oxidation. But degradation in different catechins as well as formation of different TF was significantly affected by CA pressure. At high CA pressure, TF showed highest peak value. TR was found to have slower rate of formation during initial phase of oxidation than TF. Even though the rate of TR formation was significantly influenced by CA, a portion of catechins remained unoxidized at end of oxidation. Except caffeine, the percent change in rate of formation or degradation were more prominent at 202 kPa. © 2016 Institute of Food Technologists®

  16. Dry air oxidation kinetics of K-Basin spent nuclear fuel

    International Nuclear Information System (INIS)

    Abrefah, J.; Buchanan, H.C.; Gerry, W.M.; Gray, W.J.; Marschman, S.C.

    1998-06-01

    The safety and process analyses of the proposed Integrated Process Strategy (IPS) to move the N-Reactor spent nuclear fuel (SNF) stored at K-Basin to an interim storage facility require information about the oxidation behavior of the metallic uranium. Limited experiments have been performed on the oxidation reaction of SNF samples taken from an N-Reactor outer fuel element in various atmospheres. This report discusses studies on the oxidation behavior of SNF using two independent experimental systems: (1) a tube furnace with a flowing gas mixture of 2% oxygen/98% argon; and (2) a thermogravimetric system for dry air oxidation

  17. Market turkey performance, air quality, and energy consumption affected by partial slotted flooring.

    Science.gov (United States)

    Noll, S L; Janni, K A; Halvorson, D A; Clanton, C J

    1997-02-01

    Two experiments were conducted with 600 male Large White turkeys to examine performance and health when reared from 5 to 18 wk of age on litter (L) partially slotted flooring (SF), and under two ventilation rates-control and reduced ventilation (80% control). In both experiments, body weights were improved significantly (P Ammonia levels were reduced with SF, whereas dust levels were increased. Ventilation rate did not affect turkey performance. Ammonia and carbon dioxide levels were increased with reduced ventilation in Experiment 1. Dust levels were not affected by ventilation rate. Supplemental energy use was decreased in the SF system or by reducing the ventilation rate. In comparison to the control ventilation/litter treatment, the greatest decrease in energy use was observed with SF at 80% ventilation rates. Results indicate that the use of SF in a cold climate can improve body weight and substantially reduce energy use when excessive litter moisture is a problem. However, a greater incidence of blisters will limit application of SF due to lowered carcass quality and value.

  18. Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations

    Science.gov (United States)

    Robles, Guillermo; Fresno, José Manuel; Sánchez-Fernández, Matilde; Martínez-Tarifa, Juan Manuel

    2016-01-01

    Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array. PMID:27092501

  19. Induction of genetic changes in Saccharomyces cerevisiae by partial drying in air of constant relative humidity and by UV

    International Nuclear Information System (INIS)

    Hieda, K.

    1981-01-01

    It was investigated whether there was a critical degree of dryness for induction of genetic changes by drying. Saccharomyces cerevisiae cells were dried in air of 0.33, 53 and 76% relative humidity (RH). The frequencies of mitotic recombination at ade2, of gene conversion at leu1, and of gene mutation at can1 were measured in X2447, XS1473 and S288C strains, respectively. After the cells had been dried at 0% RH for 4 h the frequencies of the genetic changes at ade2, leu1 and can1 were, respectively, 56, 7 and 3.5 times higher than each spontaneous frequency. Induction rates, defined as the frequencies of the induced genetic changes per unit time (1 h) of drying, were greatly decreased with increase in RH. Partial drying in air of 76% RH up to 4 and 8 h induced no genetic change at ade2 and leu1, respectively. It was concluded, therefore, that drying at a certain RH between 53 and 76% gave the critical degreee of dryness of cells for the induction of the genetic changes. The water contents of cells (g water per g dry material) were 12% at 53% RH and 21% at 76% RH, whereas the water content of native cells was 212%. Removal of a large amount of cellular water had no effect on the induction of the genetic changes. UV sensitivity of partially dried cells of X2447 for the induction of the genetic change at ade2 drastically increased with decrease in RH between 76 and 53%. The drastic change in the UV sensitivity suggested that photochemical reactivity of DNA of chromosome XV, in which the ade2 locus is located, changed between 76 and 53% RH. It seems that the genetic changes were induced only in the low RH region where DNA in vivo had a different photochemical reactivity. (orig.)

  20. Kinetics and mechanism of the oxidation of cerium in air at ambient temperature

    International Nuclear Information System (INIS)

    Wheeler, D.W.

    2016-01-01

    Highlights: • XRD and transverse sections suggest Ce_2O_3 forms on Ce before being overlaid by CeO_2. • XRD and oxide thickness measurements both indicate linear oxidation. • Extensive cracking on oxide surface which sustains continuing oxidation. • Electron microscopy has shown features indicative of nodular oxidation. • Oxide growth rate determined to be 0.1 μm day"−"1 under the conditions in this study. - Abstract: This paper describes a study of the oxidation of cerium in air at ambient temperature. Specimens were exposed for up to 60 days, during which they were analysed by X-ray diffraction (XRD) at regular intervals. Both XRD and oxide thickness measurements indicate linear oxidation over the duration of this study. Under the conditions employed in this study, the rate of oxide growth has been determined to be 0.1 μm day"−"1. The oxidation process appears to be assisted by extensive cracking in the oxide layer which acts as a non-protective film for the underlying metal.

  1. Borax partially prevents neurologic disability and oxidative stress in experimental spinal cord ischemia/reperfusion injury.

    Science.gov (United States)

    Koc, Emine Rabia; Gökce, Emre Cemal; Sönmez, Mehmet Akif; Namuslu, Mehmet; Gökce, Aysun; Bodur, A Said

    2015-01-01

    The aim of this study is to investigate the potential effects of borax on ischemia/reperfusion injury of the rat spinal cord. Twenty-one Wistar albino rats were divided into 3 groups: sham (no ischemia/reperfusion), ischemia/reperfusion, and borax (ischemia/reperfusion + borax); each group was consist of 7 animals. Infrarenal aortic cross clamp was applied for 30 minutes to generate spinal cord ischemia. Animals were evaluated functionally with the Basso, Beattie, and Bresnahan scoring system and inclined-plane test. The spinal cord tissue samples were harvested to analyze tissue concentrations of nitric oxide, nitric oxide synthase activity, xanthine oxidase activity, total antioxidant capacity, and total oxidant status and to perform histopathological examination. At the 72nd hour after ischemia, the borax group had significantly higher Basso, Beattie, and Bresnahan and inclined-plane scores than those of ischemia/reperfusion group. Histopathological examination of spinal cord tissues in borax group showed that treatment with borax significantly reduced the degree of spinal cord edema, inflammation, and tissue injury disclosed by light microscopy. Xanthine oxidase activity and total oxidant status levels of the ischemia/reperfusion group were significantly higher than those of the sham and borax groups (P borax group were significantly higher than those of the ischemia/reperfusion group (P borax groups in terms of total antioxidant capacity levels (P > .05). The nitric oxide levels and nitric oxide synthase activity of all groups were similar (P > .05). Borax treatment seems to protect the spinal cord against injury in a rat ischemia/reperfusion model and improve neurological outcome. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  2. Characterization and comprehension of corona partial discharge in air under power frequency to very low frequency voltage

    Science.gov (United States)

    Yuanxiang, ZHOU; Zhongliu, ZHOU; Ling, ZHANG; Yunxiao, ZHANG; Yajun, MO; Jiantao, SUN

    2018-05-01

    For the partial discharge test of electrical equipment with large capacitance, the use of low-frequency voltage instead of power frequency voltage can effectively reduce the capacity requirements of test power supply. However, the validity of PD test under low frequency voltage needs to be evaluated. In order to investigate the influence of voltage frequency on corona discharge in the air, the discharge test of the tip-plate electrode under the frequency from 50 to 0.1 Hz is carried out based on the impulse current method. The results show that some of the main features of corona under low frequency do not change. The magnitude of discharge in a positive half cycle is obviously larger than that in a negative cycle. The magnitude of discharge and interval in positive cycle are random, while that in negative cycle are regular. With the decrease of frequency, the inception voltage increases. The variation trend of maximum and average magnitude and repetition rate of the discharge in positive and negative half cycle with the variation of voltage frequency and magnitude is demonstrated, with discussion and interpretation from the aspects of space charge transportation, effective discharge time and transition of discharge modes. There is an obvious difference in the phase resolved pattern of partial discharge and characteristic parameters of discharge patterns between power and low frequency. The experimental results can be the reference for mode identification of partial discharge under low frequency tests. The trend of the measured parameters with the variation of frequency provides more information about the insulation defect than traditional measurements under a single frequency (usually 50 Hz). Also it helps to understand the mechanism of corona discharge with an explanation of the characteristics under different frequencies.

  3. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    International Nuclear Information System (INIS)

    Uddi, M; Jiang, N; Adamovich, I V; Lempert, W R

    2009-01-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ∼8 x 10 12 cm -3 (∼4.14 ppm) occurring at ∼250 μs after the pulse, with decay time of ∼16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of ψ = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of ψ = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N 2 (C 3 Π) and NO(A 2 Σ) in air at P = 60 Torr decay within ∼20 ns and ∼1 μs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (∼100 μs) metastable states, such as N 2 (X 1 Σ,v) and O 2 (b 1 Σ), formed by quenching of the metastable N 2 (A 3 Σ) state by ground electronic state O 2 , may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O 2 , as well as by conversion into NO 2 in a reaction

  4. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    Science.gov (United States)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  5. Room air versus carbon dioxide pneumoperitoneum: effects on oxidative state, apoptosis and histology of splanchnic organs.

    Science.gov (United States)

    Ypsilantis, Petros; Lambropoulou, Maria; Tentes, Ioannis; Chryssidou, Maria; Georgantas, Themistoklis; Simopoulos, Constantinos

    2016-04-01

    Although CO2 is the insufflation gas of choice in laparoscopic procedures, room air is usually used in natural orifice transluminal endoscopic surgery. The aim of the present study was to compare the safety of room air versus CO2 pneumoperitoneum in terms of their effect on the oxidative state, apoptosis and tissue injury of splanchnic organs. Eighteen Wistar rats were assigned to three groups (n = 6 per group) and were subjected to 8 mm Hg room air (group Pne-Air) or CO2 pneumoperitoneum (group Pne-CO2) or sham operation for 60 min. Forty-five minutes postdeflation, tissue samples were excised from the liver, stomach, ileum and kidneys for reduced glutathione-to-glutathione disulfide (GSH/GSSG) ratio, caspase-8 and caspase-3 and hypoxia-inducible factor-1α (HIF-1α) immunohistochemical assessment and histopathologic examination. GSH/GSSG ratio substantially declined in both pneumoperitoneum groups. No change was noted in HIF-1α expression. Mild upregulation of caspase-8 and caspase-3 was noted in both pneumoperitoneum groups being less pronounced in group Pne-Air. Histopathologic score was increased in all organs studied, but the stomach, in both pneumoperitoneum groups. Pneumoperitoneum established by either room air or CO2 induced substantial oxidative stress, mild apoptosis and mild tissue injury in splanchnic organs. While air pneumoperitoneum conferred a less pronounced apoptotic effect, the oxidative state and histopathologic profile of splanchnic organs did not differ between insufflation gases.

  6. Effect of primary air content on formation of nitrogen oxides during combustion of Ehkibastuz coal

    Energy Technology Data Exchange (ETDEWEB)

    Kotler, V.R.; Imankulov, Eh.R.

    1986-01-01

    Investigations are discussed carried out in a pilot plant at the Kaz. Power Engineering Scientific Research Institute into the effect of the amount of primary air in coal-dust flame on the final concentration of nitrogen oxides in flue gases. The tests were carried out in a 7500 mm high, 1600 mm dia vertical cylindrical combustion chamber having type P-57 burner, and air dispersed fuel plus additional air supplies located at the top. Amounts of coal dust fed by a drum feeder along the air pipe varied from 100-600 kg/h. The required air was supplied by 5000 m/sup 3//h Type TK-700/5 blowers at 0.04 MPa. Ehkibastuz coal samples contained: 1.3% moisture; 48.1% ash; 38.02% carbon; 2.56% hydrogen; 0.73% sulfur; 0.60% nitrogen; heat of combustion was 14.3 MJ/kg. Results obtained indicate that variations in the amount of primary air in swirl flow burners affect formation of fuel nitrogen; there is an optimum volume at which minimum quantities of nitrogen oxides are formed. Either an increase or decrease in the primary air results in a rise in nitrogen oxide concentration. 3 references.

  7. Isothermal Oxidation of Magnetite to Hematite in Air and Cyclic Reduction/Oxidation Under Carbon Looping Combustion Conditions

    Science.gov (United States)

    Simmonds, Tegan; Hayes, Peter C.

    2017-12-01

    In the carbon looping combustion process the oxygen carrier is regenerated through oxidation in air; this process has been simulated by the oxidation of dense synthetic magnetite for selected temperatures and times. The oxidation of magnetite in air is shown to occur through the formation of dense hematite layers on the particle surface. This dense hematite forms through lath type shear transformations or solid-state diffusion through the product layer. Cyclic reduction in CO-CO2/oxidation in air of hematite single crystals has been carried out under controlled laboratory conditions at 1173 K (900 °C). It has been shown that the initial reduction step is critical to determining the product microstructure, which consists of gas pore dendrites in the magnetite matrix with blocky hematite formed on the pore surfaces. The progressive growth of the magnetite layer with the application of subsequent cycles appears to continue until no original hematite remains, after which physical disintegration of the particles takes place.

  8. Nitrous oxide production in intermittently aerated Partial Nitritation-Anammox reactor: oxic N2O production dominates and relates with ammonia removal rate

    DEFF Research Database (Denmark)

    Blum, Jan-Michael; Jensen, Marlene Mark; Smets, Barth F.

    2018-01-01

    Emissions of the greenhouse gas nitrous oxide from the Partial Nitritation-Anammox process are of concern and can determine the carbon footprint of the process. In order to reduce nitrous oxide emissions intermittent aeration regimes have been shown to be a promising mode of operation, possibly due...

  9. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    Science.gov (United States)

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  10. Air oxidation of Zircaloy-4, M5 (registered) and ZIRLOTM cladding alloys at high temperatures

    International Nuclear Information System (INIS)

    Steinbrueck, M.; Boettcher, M.

    2011-01-01

    The paper presents the results of isothermal and transient oxidation experiments of the advanced cladding alloys M5 (registered) and ZIRLO TM in comparison to Zircaloy-4 in air at temperatures from 973 to 1853 K. Generally, oxidation in air leads to a strong degradation of the cladding material. The main mechanism of this process is the formation of zirconium nitride and its re-oxidation. From the point of view of safety, the barrier effect of the fuel cladding is lost much earlier than during accident transients with a steam atmosphere only. Comparison of the three alloys investigated reveals a qualitatively similar, but quantitatively varying oxidation behavior in air. The mainly parabolic oxidation kinetics, where applicable, is comparable for the three alloys. Strong differences of up to 500% in oxidation rates were observed after transition to linear kinetics at temperatures below 1300 K. The paper presents kinetic rate constants as well as critical times and oxide scale thicknesses at the point of transition from parabolic to linear kinetics.

  11. Characteristics of hydrogen produced by partial oxidation and auto-thermal reforming in a small methanol reformer

    Science.gov (United States)

    Horng, Rong-Fang; Chou, Huann-Ming; Lee, Chiou-Hwang; Tsai, Hsien-Te

    This paper investigates experimentally, the transient characteristics of a small methanol reformer using partial oxidation (POX) and auto-thermal reforming (ATR) for fuel cell applications. The parameters varied were heating temperature, methanol supply rate, steady mode shifting temperature, O 2/C (O 2/CH 3OH) and S/C (H 2O/CH 3OH) molar ratios with the main aim of promoting a rapid response and a high flow rate of hydrogen. The experiments showed that a high steady mode shifting temperature resulted in a faster temperature rise at the catalyst outlet and vice versa and that a low steady mode shifting temperature resulted in a lower final hydrogen concentration. However, when the mode shifting temperature was too high, the hydrogen production response was not necessarily improved. It was subsequently shown that the optimum steady mode shifting temperature for this experimental set-up was approximately 75 °C. Further, the hydrogen concentration produced by the auto-thermal process was as high as 49.12% and the volume flow rate up to 23.0 L min -1 compared to 40.0% and 20.5 L min -1 produced by partial oxidation.

  12. Fuel processor integrated H{sub 2}S catalytic partial oxidation technology for sulfur removal in fuel cell power plants

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, T.H.; Berry, D.A.; Lyons, K.D.; Beer, S.K.; Freed, A.D. [U.S. Department of Energy, Morgantown, WV (USA). National Energy Technology Laboratory

    2002-12-01

    H{sub 2}S catalytic partial oxidation technology with an activated carbon catalyst was found to be a promising method for the removal of hydrogen sulfide from fuel cell hydrocarbon feedstocks. Three different fuel cell feedstocks were considered for analysis: sour natural gas, sour effluent from a liquid middle distillate fuel processor and a Texaco O{sub 2}-blown coal-derived synthesis gas. The H{sub 2}S catalytic partial oxidation reaction, its integratability into fuel cell power plants with different hydrocarbon feedstocks and its salient features are discussed. Experimental results indicate that H{sub 2}S concentration can be removed down to the part-per-million level in these plants. Additionally, a power law rate expression was developed and reaction kinetics compared to prior literature. The activation energy for this reaction was determined to be 34.4 kJ/g mol with the reaction being first order in H{sub 2}S and 0.3 order in O{sub 2}. 18 refs., 14 figs., 3 tabs.

  13. Partial oxidation of methane to methanol over catalyst ZSM-5 from coal fly ash and rice husk ash

    Directory of Open Access Journals (Sweden)

    Mirda Yanti Fusia

    2017-01-01

    Full Text Available Methane is one of the greenhouse gases that can be converted into liquid fuels such as methanol to retain most of the energy of methane and produce a cleaner environment. The conversion of methane to methanol using ZMS-5 represents a breakthrough in the utilization of methane. However, material sources for zeolite synthesis as catalyst usually are pro-analysis grade materials, which are expensive. Therefore, in this research, coal fly ash and rice husk ash were used as raw materials for mesoporous ZSM-5 zeolite synthesis. First, coal fly ash and rice husk were subjected to pre-treatment to extract silicate (SiO44− and aluminate (AlO45− and impurities separation. The ZSM-5 zeolite was synthesized through hydrothermal treatment using two types of templates. After ZSM-5 was synthesized, it was modified with Cobalt through impregnation method. The catalytic activity of both ZSM-5 and Co/ZSM-5 zeolites as heterogeneous catalysts in partial oxidation of methane were preliminary tested and compared with that commercial one. The result showed that the zeolite catalyst ZSM-5 from fly ash coal and rice husk ash has the potential to be used as catalysts in the partial oxidation of methane to methanol.

  14. Hydrogen production with short contact time. Catalytic partial oxidation of hydrocarbons and oxygenated compounds: Recent advances in pilot- and bench-scale testing and process design

    Energy Technology Data Exchange (ETDEWEB)

    Guarinoni, A.; Ponzo, R.; Basini, L. [ENI Refining and Marketing Div., San Donato Milanese (Italy)

    2010-12-30

    ENI R and D has been active for fifteen years in the development of Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technologies for producing Hydrogen/Synthesis Gas. From the beginning the experimental work addressed either at defining the fundamental principles or the technical and economical potential of the technology. Good experimental responses, technical solutions' simplicity and flexibility, favourable techno-economical evaluations promoted the progressive widening of the field of the investigations. From Natural Gas (NG) the range of ''processable'' Hydrocarbons extended to Liquefied Petroleum Gas (LPG) and Gasoils, including those characterised by high levels of unsaturated and sulphurated molecules and, lately, to other compounds with biological origin. The extensive work led to the definition of different technological solutions, grouped as follows: Technology 1: Air Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 2: Enriched Air/Oxygen Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 3: Enriched Air/Oxygen Blown SCT-CPO of Liquid Hydrocarbons and/or Compounds with biological origin Recently, the licence rights on a non-exclusive basis for the commercialisation of SCT-CPO based processes for H{sub 2}/Synthesis gas production from light hydrocarbons with production capacity lower than 5,000 Nm{sup 3}/h of H{sub 2} or 7,500 Nm3/h of syngas have been assigned to two external companies. In parallel, development of medium- and large-scale plant solutions is progressing within the ENI group framework. These last activities are addressed to the utilisation of SCT-CPO for matching the variable Hydrogen demand in several contexts of oil refining operation. This paper will report on the current status of SCT-CPO with a focus on experimental results obtained, either at pilot- and bench- scale level. (orig.)

  15. Oxidation of X20 in Water Vapour: The Effect of Temperature and Oxygen Partial Pressure

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Montgomery, Melanie; Somers, Marcel A. J.

    2009-01-01

    The oxidation behaviour of X20 in various mixtures of water, oxygen and hydrogen was investigated at temperatures between 500 C and 700 C (time: 336 h). The samples were characterised using reflected light microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy...

  16. Catalytic ring-​opening copolymerization of limonene oxide and phthalic anhydride : toward partially renewable polyesters

    NARCIS (Netherlands)

    Hosseini Nejad, E.; Pionasari, A; Melis, van C.G.W.; Koning, C.E.; Duchateau, R.

    2013-01-01

    Catalytic ring-¿opening copolymn. of limonene oxide with phthalic anhydride was performed applying metal t-¿Bu-¿salophen complexes (t-¿Bu-¿salophen)¿MX; M = Cr, X = Cl (1)¿, M = Al, X = Cl (2)¿, M = Co, X = OAc (3)¿, M = Mn, X = Cl (4)¿, t-¿Bu-¿salophen =

  17. Catalysis by Atomic-Sized Centers: Methane Activation for Partial Oxidation and Combustion

    Science.gov (United States)

    2015-07-21

    example, H adsorbed alone on an oxide surface will bind to oxygen to form a hydroxide . However, if a Lewis base (e.g. any electron donor) is...that on a gold surface, which is not surprising considering the bonding character between the cluster and metal surfaces. The high mobility verifies

  18. Air-water two-phase flow in a four by four rod bundle with partial length rods

    International Nuclear Information System (INIS)

    Ohta, Motoki; Kamei, Akihiro; Mizutani, Yoshitaka; Hosokawa, Shigeo; Tomiyama, Akio

    2009-01-01

    Partial length rods (PLR) are used in fuel bundles of BWR to reduce pressure drops in two-phase regions and to optimize the power distribution. Since little is known about effects of PLR on two-phase flows, air-water two-phase flow around PLRs in a four by four rod bundle is visualized by using a high-speed video camera. The experimental apparatus consists of acrylic channel box and transparent rods. Air and water at atmospheric pressure and room temperature are used for the gas and liquid phases, respectively. The ranges of the gas and liquid volume fluxes, J G and J L , are 0.4 L G L , the flow pattern in the downstream of PLR transits to slug flow, and the flow patterns in the surrounding subchannels transit to bubbly flow due to the redistribution of gas flow. (2) In annular flow, the liquid film on the PLR forms a liquid column above the end cap of PLR. Droplets are generated by column breakup and deposit on liquid films on the neighboring rods. (3) The liquid film thickness on the surface of neighbor rods facing the PLR increases and it reduces that on their opposite surface in the downstream of PLR. (author)

  19. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall, process control via online N2O monitoring was confirmed to be an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. ReferencesWaechter H. et al. (2008) Optics Express, 16: 9239-9244. Wunderlin, P et al. (2013) Environmental Science & Technology 47: 1339-1348.

  20. A new partial SOI-LDMOSFET with a modified buried oxide layer for improving self-heating and breakdown voltage

    International Nuclear Information System (INIS)

    Jamali Mahabadi, S E; Orouji, Ali A; Keshavarzi, P; Moghadam, Hamid Amini

    2011-01-01

    In this paper, for the first time, we propose a partial silicon-on-insulator (P-SOI) lateral double-diffused metal-oxide-semiconductor-field-effect-transistor (LDMOSFET) with a modified buried layer in order to improve breakdown voltage (BV) and self-heating effects (SHEs). The main idea of this work is to control the electric field by shaping the buried layer. With two steps introduced in the buried layer, the electric field distribution is modified. Also a P-type window introduced makes the substrate share the vertical voltage drop, leading to a high vertical BV. Moreover, four interface electric field peaks are introduced by the buried P-layer, the Si window and two steps, which modulate the electric field in the SOI layer and the substrate. Hence, a more uniform electric field is obtained; consequently, a high BV is achieved. Furthermore, the Si window creates a conduction path between the active layer and substrate and alleviates the SHE. Two-dimensional simulations show that the BV of double step partial silicon on insulator is nearly 69% higher and alleviates SHEs 17% in comparison with its single step partial SOI counterpart and nearly 265% higher and alleviate SHEs 18% in comparison with its conventional SOI counterpart

  1. Comparison of partial and full nitrification processes applied for treating high-strength nitrogen wastewaters: microbial ecology through nitrous oxide production.

    Science.gov (United States)

    Ahn, Joon Ho; Kwan, Tiffany; Chandran, Kartik

    2011-04-01

    The goal of this study was to compare the microbial ecology, gene expression, biokinetics, and N2O emissions from a lab-scale bioreactor operated sequentially in full-nitrification and partial-nitrification modes. Based on sequencing of 16S rRNA and ammonia monooxygenase subunit A (amoA) genes, ammonia oxidizing bacteria (AOB) populations during full- and partial-nitrification modes were distinct from one another. The concentrations of AOB (XAOB) and their respiration rates during full- and partial-nitrification modes were statistically similar, whereas the concentrations of nitrite oxidizing bacteria (XNOB) and their respiration rates declined significantly after the switch from full- to partial-nitrification. The transition from full-nitrification to partial nitrification resulted in a protracted transient spike of nitrous oxide (N2O) and nitric oxide (NO) emissions, which later stabilized. The trends in N2O and NO emissions correlated well with trends in the expression of nirK and norB genes that code for the production of these gases in AOB. Both the transient and stabilized N2O and NO emissions during partial nitrification were statistically higher than those during steady-state full-nitrification. Based on these results, partial nitrification strategies for biological nitrogen removal, although attractive for their reduced operating costs and energy demand, may need to be optimized against the higher carbon foot-print attributed to their N2O emissions.

  2. Simulation with GOTHIC of experiments Oxidation of fuel in Air

    International Nuclear Information System (INIS)

    Martinez-Murillo Mendez, J. C.

    2012-01-01

    In the present work has been addressed for the first time la simulation with the GOTHIC code, experiments oxidation and ignition of SFP in phase 1. This work represents a solid starting point for analysis of specific degradation of fuel in the pools of our facilities.

  3. Continuous measurements of ammonia, nitrous oxide and methane from air scrubbers at pig housing facilities.

    Science.gov (United States)

    Van der Heyden, C; Brusselman, E; Volcke, E I P; Demeyer, P

    2016-10-01

    Ammonia, largely emitted by agriculture, involves a great risk for eutrophication and acidification leading to biodiversity loss. Air scrubbers are widely applied to reduce ammonia emission from pig and poultry housing facilities, but it is not always clear whether their performance meets the requirements. Besides, there is a growing international concern for the livestock related greenhouse gases methane and nitrous oxide but hardly any data concerning their fate in air scrubbers are available. This contribution presents the results from measurement campaigns conducted at a chemical, a biological and a two-stage biological air scrubber installed at pig housing facilities in Flanders. Ammonia, nitrous oxide and methane at the inlet and outlet of the air scrubbers were monitored on-line during one week using a photoacoustic gas monitor, which allowed to investigate diurnal fluctuations in the removal performance of air scrubbers. Additionally, the homogeneity of the air scrubbers, normally checked by gas detection tubes, was investigated in more detail using the continuous data. The biological air scrubber with extra nitrification tank performed well in terms of ammonia removal (86 ± 6%), while the two-stage air scrubber suffered from nitrifying bacteria inhibition. In the chemical air scrubber the pH was not kept constant, lowering the ammonia removal efficiency. A lower ammonia removal efficiency was found during the day, when the ventilation rate was the highest. Nitrous oxide was produced inside the biological and two-stage scrubber, resulting in an increased outlet concentration of more than 200%. Methane could not be removed in the different air scrubbers because of its low water solubility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Improvement of performance in low temperature solid oxide fuel cells operated on ethanol and air mixtures using Cu-ZnO-Al2O3 catalyst layer

    Science.gov (United States)

    Morales, M.; Espiell, F.; Segarra, M.

    2015-10-01

    Anode-supported single-chamber solid oxide fuel cells with and without Cu-ZnO-Al2O3 catalyst layers deposited on the anode support have been operated on ethanol and air mixtures. The cells consist of gadolinia-doped ceria electrolyte, Ni-doped ceria anode, and La0.6Sr0.4CoO3-δ-doped ceria cathode. Catalyst layers with different Cu-ZnO-Al2O3 ratios are deposited and sintered at several temperatures. Since the performance of single-chamber fuel cells strongly depends on catalytic properties of electrodes for partial oxidation of ethanol, the cells are electrochemically characterized as a function of the temperature, ethanol-air molar ratio and gas flow rate. In addition, catalytic activities of supported anode, catalytic layer-supported anode and cathode for partial oxidation of ethanol are analysed. Afterwards, the effect of composition and sintering temperature of catalyst layer on the cell performance are determined. The results indicate that the cell performance can be significantly enhanced using catalyst layers of 30:35:35 and 40:30:30 wt.% Cu-ZnO-Al2O3 sintered at 1100 °C, achieving power densities above 50 mW cm-2 under 0.45 ethanol-air ratio at temperatures as low as 450 °C. After testing for 15 h, all cells present a gradual loss of power density, without carbon deposition, which is mainly attributed to the partial re-oxidation of Ni at the anode.

  5. Session 6: Water depollution from aniline and phenol by air oxidation and adsorptive-catalytic oxidation in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Dobrynkin, N.M.; Batygina, M.V.; Noskov, A.S. [Boreskov Institute of Catalysis of Siberian Branch of Russian Academy of Sciences, Pr. Ak. Lavrentieva (Russian Federation)

    2004-07-01

    This paper is devoted to development of carbon catalysts and application of catalytic wet air oxidation for deep cleaning of polluted waters. The described catalysts and method are solving the problem of development environmentally reliable method for fluids treatment and allow carrying out the adsorption of pollutants on carbon CAPM (catalytically active porous material) with following regeneration of the CAPM without the loss of adsorptive qualities. The experiments have shown a principal capability simultaneously to use carbon CAPM as adsorbent and either as catalyst, or as a catalyst support for oxidation of aniline and phenol in water solutions. (authors)

  6. Oxidative stress and inflammation generated DNA damage by exposure to air pollution particles

    DEFF Research Database (Denmark)

    Møller, Peter; Danielsen, Pernille Høgh; Karottki, Dorina Gabriela

    2014-01-01

    at different locations (spatial variability), times (temporal variability) or particle size fraction across different experimental systems of acellular conditions, cultured cells, animals and humans. Nevertheless, there is substantial variation in the genotoxic, inflammation and oxidative stress potential......Generation of oxidatively damaged DNA by particulate matter (PM) is hypothesized to occur via production of reactive oxygen species (ROS) and inflammation. We investigated this hypothesis by comparing ROS production, inflammation and oxidatively damaged DNA in different experimental systems...... investigating air pollution particles. There is substantial evidence indicating that exposure to air pollution particles was associated with elevated levels of oxidatively damaged nucleobases in circulating blood cells and urine from humans, which is supported by observations of elevated levels of genotoxicity...

  7. Increased penile expression of transforming growth factor and elevated systemic oxidative stress in rabbits with chronic partial bladder outlet obstruction.

    Science.gov (United States)

    Lin, W-Y; Chang, P-J; Lin, Y-P; Wu, S-B; Chen, C-S; Levin, R M; Wei, Y-H

    2012-02-01

    There is a growing body of evidence to support the direct link between obstructive bladder dysfunction and erectile dysfunction (ED). However, there have been few pathophysiological studies to determine the relationship between lower urinary tract syndrome (LUTS) and ED. As the transforming growth factor-β1 (TGF-β1) that induces the synthesis of collagen in the penile tissues is critical for the development of ED, the first aim of this study was to investigate the expression of TGF-β1 in the penis from male rabbits with chronic partial bladder outlet obstruction (PBOO). Besides, it has been suggested that oxidative stress plays a significant role in the pathophysiological mechanism of ED. Thus, the second aim of this study was to further investigate whether the urinary or serum oxidative stress markers are involved in chronic PBOO-induced penile dysfunction. A total of 16 male New Zealand White rabbits were separated equally into four groups: a control group and PBOO groups obstructed for 2, 4 and 8 weeks respectively. Using the RT-PCR and Western blot analysis, a progressive increase of TGF-β1 in penis was found at 2, 4 and 8 weeks after obstruction. Moreover, the biomarkers for oxidative stress or oxidative damage were significantly detected in the penis of rabbits after PBOO, which include the enhancement of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine and plasma, plasma malondialdehyde (MDA) and total antioxidant capacity (TAC), as well as reduction of glutathione (GSH). On the basis of our results, the increase of TGF-β1 and elevated systemic oxidative stress may play key roles to contribute to penile dysfunction after chronic PBOO. © 2011 The Authors. International Journal of Andrology © 2011 European Academy of Andrology.

  8. Steam and partial oxidation reforming options for hydrogen production from fossil fuels for PEM fuel cells

    OpenAIRE

    Yousri M.A. Welaya; Mohamed M. El Gohary; Nader R. Ammar

    2012-01-01

    Proton exchange membrane fuel cell (PEM) generates electrical power from air and from hydrogen or hydrogen rich gas mixtures. Therefore, there is an increasing interest in converting current hydrocarbon based marine fuels such as natural gas, gasoline, and diesel into hydrogen rich gases acceptable to the PEM fuel cells on board ships. Using chemical flow sheeting software, the total system efficiency has been calculated. Natural gas appears to be the best fuel for hydrogen rich gas productio...

  9. The oxidation behaviour of uranium in air at 348-765 K

    International Nuclear Information System (INIS)

    Bennett, M.J.; Price, J.B.

    1981-01-01

    The oxidation behaviour of adjusted uranium has been examined in air, at atmospheric pressure, at 348-765 K. Particular emphasis has been directed to the role of swelling resulting from prior irradiation of the metal to a burn-up of 5600-9100 MWd/t and an addition of 2.5 x 10 4 vpm water vapour to the air. Pre-irradiation of uranium enhanced its attack by air at 348-523 K, the enhancement increasing progressively with percentage swelling. This effect resulted primarily from the break-up of the uranium surface during oxidation with the generation of a greater reaction surface area and was independent of the temperature of oxidation in dry air and also above 423 K in wet air. At lower temperatures, however, the water vapour addition increased the effective reaction rate, possibly by the transistory involvement of uranium hybride. The influence of the water vapour increased with swelling of the irradiated uranium and was greater than that exerted on the oxidation of unirradiated uranium at comparable temperatures. With increasing temperature above 623 K, swelling had a progressively decreasing influence upon the attack of irradiated uranium in both environments. (orig.)

  10. DISCHARGE OXIDE STORAGE CAPACITY AND VOLTAGE LOSS IN LI-AIR BATTERY

    International Nuclear Information System (INIS)

    Wang, Yun; Wang, Zhe; Yuan, Hao; Li, Tianqi

    2015-01-01

    Air cathodes, where oxygen reacts with Li ions and electrons with discharge oxide stored in their pore structure, are often considered as the most challenging component in nonaqueous Lithium-air batteries. In non-aqueous electrolytes, discharge oxides are usually insoluble and hence precipitate at local reaction site, raising the oxygen transport resistance in the pore network. Due to their low electric conductivity, their presence causes electrode passivation. This study aims to investigate the air cathode’s performance through analytically obtaining oxygen profiles, modeling electrode passivation, evaluating the transport polarization raised by discharge oxide precipitate, and developing analytical formulas for insoluble Li oxides storage capacity. The variations of cathode quantities, including oxygen content and temperature, are evaluated and related to a single dimensionless parameter — the Damköhler Number (Da). An approximate model is developed to predict discharge voltage loss, along with validation against two sets of experimental data. Air cathode properties, including tortuosity, surface coverage factor and the Da number, and their effects on the cathode’s capacity of storing Li oxides are formulated and discussed.

  11. Effects of Urtica dioica on oxidative stress, proliferation and apoptosis after partial hepatectomy in rats.

    Science.gov (United States)

    Oguz, Serhat; Kanter, Mehmet; Erboga, Mustafa; Toydemir, Toygar; Sayhan, Mustafa Burak; Onur, Hatice

    2015-05-01

    The present study was performed to investigate the effect of Urtica dioica (UD) on liver regeneration after partial hepatectomy (PH) in rats. A total of 24 male Sprague Dawley rats were divided into three groups: sham-operated, PH and PH + UD; each group contains eight animals. The rats in UD-treated groups were given UD oils (2 ml/kg/day) once a day orally for 7 days starting 3 days prior to hepatectomy operation. At day 7 after resection, liver samples were collected. The levels of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) were estimated in liver homogenates. Moreover, histopathological examination, mitotic index (MI), proliferating cell nuclear antigen labeling, proliferation index (PI), transferase-mediated deoxyuridine triphosphate nick end-labeling assay, apoptotic index (AI) were evaluated at day 7 after hepatectomy. As a result, UD significantly increased MI and PI, significantly decreased AI and also attenuated hepatic vacuolar degeneration and sinusoidal congestion in PH rats. UD treatment significantly decreased the elevated tissue MDA level and increased the reduced SOD activity and GSH level in the tissues. These results suggest that UD pretreatment was beneficial for rat liver regeneration after partial hepatectomy. © The Author(s) 2013.

  12. Comparison of NBG-18, NBG-17, IG-110 and IG-11 oxidation kinetics in air

    Science.gov (United States)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2018-03-01

    The oxidation rates of several nuclear-grade graphites, NBG-18, NBG-17, IG-110 and IG-11, were measured in air using thermogravimetry. Kinetic parameters and oxidation behavior for each grade were compared by coke type, filler grain size and microstructure. The thickness of the oxidized layer for each grade was determined by layer peeling and direct density measurements. The results for NBG-17 and IG-11 were compared with those available in the literature and our recently reported results for NBG-18 and IG-110 oxidation in air. The finer-grained graphites IG-110 and IG-11 were more oxidized than medium-grained NBG-18 and NBG-17 because of deeper oxidant penetration, higher porosity and higher probability of available active sites. Variation in experimental conditions also had a marked effect on the reported kinetic parameters by several studies. Kinetic parameters such as activation energy and transition temperature were sensitive to air flow rates as well as sample size and geometry.

  13. Solid oxide fuel cell power plant having a fixed contact oxidation catalyzed section of a multi-section cathode air heat exchanger

    Science.gov (United States)

    Saito, Kazuo; Lin, Yao

    2015-02-17

    The multi-section cathode air heat exchanger (102) includes at least a first heat exchanger section (104), and a fixed contact oxidation catalyzed section (126) secured adjacent each other in a stack association. Cool cathode inlet air flows through cool air channels (110) of the at least first (104) and oxidation catalyzed sections (126). Hot anode exhaust flows through hot air channels (124) of the oxidation catalyzed section (126) and is combusted therein. The combusted anode exhaust then flows through hot air channels (112) of the first section (104) of the cathode air heat exchanger (102). The cool and hot air channels (110, 112) are secured in direct heat exchange relationship with each other so that temperatures of the heat exchanger (102) do not exceed 800.degree. C. to minimize requirements for using expensive, high-temperature alloys.

  14. Obtainment of zirconium oxide and partially stabilized zirconium oxide with yttrium and rare earth oxides, from Brazilian zirconite, for ceramic aim

    International Nuclear Information System (INIS)

    Ribeiro, S.

    1991-05-01

    This work presents experimental results for processing of brazilian zirconite in order to obtain zirconium oxide with Yttrium and Rare Earth oxide by mutual coprecipitation for ceramics purposes. Due to analysis of experimental results was possible to obtain the optimum conditions for each one of technological route stage, such as: alkaline fusion; acid leaching; sulfactation and coprecipitation. (author)

  15. Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Chang Ho Oh; Eung Soo Kim; Hee Cheon No; Nam Zin Cho

    2008-12-01

    The US Department of Energy is performing research and development (R&D) that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP) Program / GEN-IV Very High Temperature Reactor (VHTR). Phenomena identification and ranking studies (PIRT) to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Schultz et al., 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) are very high priority for the NGNP program. Following a loss of coolant and system depressurization, air will enter the core through the break. Air ingress leads to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heat-up of the bottom reflector and the reactor core and will cause the release of fission products eventually. The potential collapse of the bottom reflector because of burn-off and the release of CO lead to serious safety problems. For estimation of the proper safety margin we need experimental data and tools, including accurate multi-dimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model. We also need to develop effective strategies to mitigate the effects of oxidation. The results from this research will provide crucial inputs to the INL NGNP/VHTR Methods R&D project. This project is focused on (a) analytical and experimental study of air ingress caused by density-driven, stratified, countercurrent flow, (b) advanced graphite oxidation experiments, (c) experimental study of burn-off in the bottom reflector, (d) structural tests of the burnt-off bottom reflector, (e) implementation of advanced models developed during the previous tasks into the GAMMA code, (f) full air ingress and oxidation mitigation analyses, (g) development of core neutronic models, (h) coupling of the core neutronic and thermal hydraulic models, and (i

  16. OXIDATIVE-REFORMING OF METHANE AND PARTIAL OXIDATION OF METHANE REACTIONS OVER NiO/PrO2/ZrO2 CATALYSTS: EFFECT OF NICKEL CONTENT

    Directory of Open Access Journals (Sweden)

    Y. J. O. Asencios

    Full Text Available Abstract In this work the behavior of NiO-PrO2-ZrO2 catalysts containing various nickel loadings was evaluated in the partial oxidation of methane and oxidative-reforming reactions of methane. The catalysts were characterized by X-Ray Diffraction Analysis (in situ-XRD, Temperature Programmed Reduction (H2-TPR, Scanning Electron Microscopy (SEM/EDX and Adsorption-Desorption of nitrogen (BET area. The reactions were carried out at 750 °C and 1 atm for 5 hours. The catalysts were studied with different nickel content: 0, 5, 10 and 15% (related to total weight of catalyst, wt%. In both reactions, the catalyst containing the mixture of the three oxides (NiO/PrO2/ZrO2 with 15% nickel (15NiPrZr catalyst showed the best activity for the conversion of the reactants into Syngas and showed high selectivity for H2 and CO. The results suggest that the promoter PrO2 and the Niº centers are in a good proportion in the catalyst with 15% Ni. Our results showed that low nickel concentrations in the catalyst led to high metallic dispersion; however, very low nickel concentrations did not favor the methane transformation into Syngas. The catalyst containing only NiO/ZrO2 in the mixture was not sufficient for the catalysis. The presence of the promoter PrO2 was very important for the catalysis of the POM.

  17. Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

    OpenAIRE

    Zheng, Bin; Liu, Yongqi; Liu, Ruixiang; Meng, Jian; Mao, Mingming

    2015-01-01

    This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h) and catalytic oxidation bed average temperature (20°C to 560°C) within the preheated catalytic oxidation reactor. The pressure drop and res...

  18. CFD investigating the air ingress accident for a HTGR simulation of graphite corrosion oxidation

    International Nuclear Information System (INIS)

    Ferng, Y.M.; Chi, C.W.

    2012-01-01

    Highlights: ► A CFD model is proposed to investigate graphite oxidation corrosion in the HTR-10. ► A postulated air ingress accident is assumed in this paper. ► Air ingress flowrate is the predicted result, instead of the preset one. ► O 2 would react with graphite on pebble surface, causing the graphite corrosion. ► No fuel exposure is predicted to be occurred under the air ingress accident. - Abstract: Through a compressible multi-component CFD model, this paper investigates the characteristics of graphite oxidation corrosion in the HTR-10 core under the postulated accident of gas duct rupture. In this accident, air in the steam generator cavity would enter into the core after pressure equilibrium is achieved between the core and the cavity, which is also called as the air ingress accident. Oxygen in the air would react with graphite on pebble surface, subsequently resulting in oxidation corrosion and challenging fuel integrity. In this paper, characteristics of graphite oxidation corrosion during the air ingress accident can be reasonably captured, including distributions of graphite corrosion amount on the different cross-sections, time histories of local corrosion amount at the monitoring points and overall corrosion amount in the core, respectively. Based on the transient simulation results, the corrosion pattern and its corrosion rate would approach to the steady-state conditions as the accident continuously progresses. The total amount of graphite corrosion during a 3-day accident time is predicted to be about 31 kg with the predicted asymptotic corrosion rate. This predicted value is less than that from the previous work of Gao and Shi.

  19. Partial IGF-1 deficiency induces brain oxidative damage and edema, which are ameliorated by replacement therapy.

    Science.gov (United States)

    Puche, Juan E; Muñoz, Úrsula; García-Magariño, Mariano; Sádaba, María C; Castilla-Cortázar, Inma

    2016-01-01

    Insulin-like growth factor 1 (IGF-1) induces multiple cytoprotective effects on every tissue, including the brain. Since the mechanisms by which IGF-1 produces neuroprotection are not fully understood, the aim of this work was to delve into the underlying mechanisms. IGF-1 deficient mice (Hz) were compared with wild type (WT) and Hz mice treated with low doses of IGF-1 (2 µg/100 g body weight/day) for 10 days (Hz + IGF). Gene expression, quantitative PCR, histology, and magnetic resonance imaging were performed in the three groups. IGF-1 deficiency induced increased oxidative damage determined by markers of lipid peroxidation and hypoxia, as well as gene expression of heat shock proteins, antioxidant enzymes, and molecules involved in inflammation, apoptosis, and mitochondrial protection. These changes correlated with edema and learning impairment in Hz mice. IGF-1 therapy improved all these alterations. In conclusion, IGF-1 deficiency is responsible for increased brain oxidative damage, edema, and impaired learning and memory capabilities which are rescued by IGF-1 replacement therapy. © 2016 International Union of Biochemistry and Molecular Biology.

  20. The uptake and excretion of partially oxidized sulfur expands the repertoire of energy resources metabolized by hydrothermal vent symbioses.

    Science.gov (United States)

    Beinart, R A; Gartman, A; Sanders, J G; Luther, G W; Girguis, P R

    2015-05-07

    Symbiotic associations between animals and chemoautotrophic bacteria crowd around hydrothermal vents. In these associations, symbiotic bacteria use chemical reductants from venting fluid for the energy to support autotrophy, providing primary nutrition for the host. At vents along the Eastern Lau Spreading Center, the partially oxidized sulfur compounds (POSCs) thiosulfate and polysulfide have been detected in and around animal communities but away from venting fluid. The use of POSCs for autotrophy, as an alternative to the chemical substrates in venting fluid, could mitigate competition in these communities. To determine whether ESLC symbioses could use thiosulfate to support carbon fixation or produce POSCs during sulfide oxidation, we used high-pressure, flow-through incubations to assess the productivity of three symbiotic mollusc genera-the snails Alviniconcha spp. and Ifremeria nautilei, and the mussel Bathymodiolus brevior-when oxidizing sulfide and thiosulfate. Via the incorporation of isotopically labelled inorganic carbon, we found that the symbionts of all three genera supported autotrophy while oxidizing both sulfide and thiosulfate, though at different rates. Additionally, by concurrently measuring their effect on sulfur compounds in the aquaria with voltammetric microelectrodes, we showed that these symbioses excreted POSCs under highly sulfidic conditions, illustrating that these symbioses could represent a source for POSCs in their habitat. Furthermore, we revealed spatial disparity in the rates of carbon fixation among the animals in our incubations, which might have implications for the variability of productivity in situ. Together, these results re-shape our thinking about sulfur cycling and productivity by vent symbioses, demonstrating that thiosulfate may be an ecologically important energy source for vent symbioses and that they also likely impact the local geochemical regime through the excretion of POSCs.

  1. Gaschromatographic proof of nitrous oxide concentrations in air by means of radiation ionization detectors

    International Nuclear Information System (INIS)

    Popp, P.; Schoentube, E.; Oppermann, G.

    1985-01-01

    For the analysis of nitrous oxide concentrations at workplaces in operating theatres, gaschromatography is a particularly suitable method if it is possible to measure nitrous oxide concentrations in the ppm to ppb region. For this, most frequently used gaschromatographic detectors (flame ionization detector, thermal conductivity detector) are unsuitable, whereas radiation ionization detectors can be used successfully. The investigations using detectors designed at the Central Institute for Isotopes and Radiation Research of the GDR Academy of Sciences showed that a high-temperature electron-capture detector (ECD), working at a temperatur of 250 0 C, enables the determination of traces of nitrous oxide with a detection limit of about 200 ppb, while the helium detector has a limit of 50 ppb of nitrous oxide in room air. Since the helium detector requires extremely pure carrier gas, the high-temperature ECD appears more suitable for analyzing nitrous oxide. (author)

  2. Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

    Directory of Open Access Journals (Sweden)

    Bin Zheng

    2015-01-01

    Full Text Available This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h and catalytic oxidation bed average temperature (20°C to 560°C within the preheated catalytic oxidation reactor. The pressure drop and resistance proportion of catalytic oxidation bed, the heat exchanger preheating section, and the heat exchanger flue gas section were measured. In addition, based on a large number of experimental data, the empirical equations of flow resistance are obtained by the least square method. It can also be used in deriving much needed data for preheated catalytic oxidation designs when employed in industry.

  3. Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

    International Nuclear Information System (INIS)

    Jodon de Villeroche, Suzanne

    1968-01-01

    The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

  4. An international multicentre study on the allergenic activity of air-oxidized R-limonene

    DEFF Research Database (Denmark)

    Bråred Christensson, Johanna; Andersen, Klaus Ejner; Bruze, Magnus

    2013-01-01

    Background. Limonene is a common fragrance terpene that, in its pure form, is not allergenic or is a very weak allergen. However, limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. Oxidized R-limonene has previously been patch tested in multicentre studies......, giving 2-3% positive patch test reactions in consecutive patients. Objectives. To investigate whether oxidized R-limonene 3.0% in petrolatum, with a stable concentration of the main haptens, limonene hydroperoxides (Lim-OOHs), could be a useful tool for the detection of contact allergy...... in an international setting. Methods. Oxidized R-limonene 3.0% (Lim-OOHs 0.33%) pet. was tested in 2900 consecutive dermatitis patients in Denmark, the United Kingdom, Singapore, Spain, Sweden, and Australia. Results. Overall, 5.2% (range 2.3-12.1%) of the patients showed a positive patch test reaction to oxidized R...

  5. Partially and fully de-alloyed glassy ribbons based on Au: Application in methanol electro-oxidation studies

    Energy Technology Data Exchange (ETDEWEB)

    Paschalidou, Eirini Maria, E-mail: epaschal@unito.it [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Scaglione, Federico [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Gebert, Annett; Oswald, Steffen [Leibniz Institut für Festkörper- und Werkstoffforschung IFW, Helmholtzstraße 20, 01069, Dresden (Germany); Rizzi, Paola; Battezzati, Livio [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy)

    2016-05-15

    In this work, electrochemical de-alloying of an amorphous alloy, Au{sub 40}Cu{sub 28}Ag{sub 7}Pd{sub 5}Si{sub 20}, cast in ribbon form by melt spinning, has been performed, obtaining self standing nanoporous materials suitable for use as electrodes for electrocatalytic applications. The de-alloying encompasses removal of less noble elements and the crystallization of Au, resulting in interconnected ligaments whose size and morphology are described as a function of time. Depending on de-alloying time, the crystals may contain residual amounts of Cu, Ag and Pd, as shown by Auger Electron Spectroscopy (AES), Energy Dispersive Spectroscopy (EDS) and Cyclic Voltammetry (CV) in a basic solution. Current density peaks in the 0.16–0.28 V range (vs Ag/AgCl) indicate that the porous ribbons are active for the electro-oxidation of methanol. The partially de-alloyed samples, which still partially contain the amorphous phase because of the shorter etching times, have finer ligaments and display peaks at lower potential. However, the current density decreases rapidly during repeated potential scans. This is attributed to the obstruction of Au sites, mainly by the Cu oxides formed during the scans. The fully de-alloyed ribbons display current peaks at about 0.20 V and remain active for hundreds of scans at more than 60% of the initial current density. They can be fully re-activated to achieve the same performance levels after a brief immersion in nitric acid. The good activity is due to trapped Ag and Pd atoms in combination with ligament morphology. - Graphical abstract: Fine ligaments and pores made by de-alloying a glassy ribbon of a Au-based alloy, homogeneously produced across the thickness (25 μm) for studying methanol's electro-oxidation behavior. - Highlights: • Size and composition of nanoporous layers tailored in de-alloying Au-based glassy ribbons. • From amorphous precursor fine crystals occur in ligaments with residual Pd and Ag. • Fully de

  6. Air-electron stream interactions during magnetic resonance IGRT. Skin irradiation outside the treatment field during accelerated partial breast irradiation

    International Nuclear Information System (INIS)

    Park, Jong Min; Shin, Kyung Hwan; Wu, Hong-Gyun; Kim, Jung-in; Park, So-Yeon; Kim, Jin Ho; Jeon, Seung Hyuck; Choi, Noorie

    2018-01-01

    To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm 2 , respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field. (orig.) [de

  7. NO formation in the burnout region of a partially premixed methane-air flame with upstream heat loss

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, A.V.; Levinsky, H.B.

    1999-09-01

    Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemical reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that {approximately}40 ppm of NO are produced in this burnout region, at temperatures between {approximately}2,100 K and {approximately}1,900 K, probably via the Zeldovich mechanism. Reducing the exit velocity of 12 cm/s reduces the flame temperature substantially, and effectively eliminates this contribution. At velocities of 12 and 8 cm/s, {approximately}10 ppm of NO are formed in the burnout region, even though the gas temperatures are too low for Zeldovich NO to be significant. Although the mechanism responsible for these observations is as yet unclear, the results are consistent with the idea that the low temperatures in the fuel-rich gases caused by upstream heat loss retard the conversion of HCN (formed via the Fenimore mechanism) to NO, with this residual HCN then being converted to NO during burnout.

  8. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    International Nuclear Information System (INIS)

    Li Jinhuan; Yang Xia; Yu Xiaodan; Xu, Leilei; Kang Wanli; Yan Wenhua; Gao Hongfeng; Liu Zhonghe; Guo Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+ /TiO 2 , where RE = Eu 3+ , Pr 3+ , Gd 3+ , Nd 3+ , and Y 3+ ) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+ , Pr 3+ )/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+ /TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  9. THE EFFECTS OF OXIDANT AIR POLLUTANTS ON SOYBEANS, SNAP BEANS AND POTATOES

    Science.gov (United States)

    During the past 5 years the impact of photochemical oxidants on soybeans and snap beans in Maryland and on potatoes in Virginia and Delaware was assessed with open-top chambers. The mean yields of four selected soybean varieties grown in open-top chambers with carbon-filtered air...

  10. Treatment of refractory organic pollutants in industrial wastewater by wet air oxidation

    Directory of Open Access Journals (Sweden)

    Mingming Luan

    2017-02-01

    Full Text Available Wet air oxidation (WAO is one of the most economical and environmentally-friendly advanced oxidation processes. It makes a promising technology for the treatment of refractory organic pollutants in industrial wastewaters. In wet air oxidation aqueous waste is oxidized in the liquid phase at high temperatures (125–320 °C and pressures (0.5–20 MPa in the presence of an oxygen-containing gas (usually air. The advantages of the process include low operating costs and minimal air pollution discharges. The present review is concerned about the literature published in the treatment of refractory organic pollutants in industrial wastewaters, such as dyes. Phenolics were taken as model pollutants in most cases. Reports on effect of treatment for the WAO of refractory organic pollutants in industrial wastewaters are reviewed, such as emulsified wastewater, TNT red water, etc. Discussions are also made on the mechanism and kinetics of WAO and main technical parameters influencing WAO. Finally, development direction of WAO is summed up.

  11. Oxidation of volatile organic vapours in air by solid potassium permanganate

    NARCIS (Netherlands)

    Mahmoodlu, M.G.; Hartog, N.; Hassanizadeh, S.M.; Raoof, A.

    2013-01-01

    Volatile organic compounds (VOCs) may frequently contaminate groundwater and pose threat to human health when migrating into the unsaturated soil zone and upward to the indoor air. The kinetic of chemical oxidation has been investigated widely for dissolved VOCs in the saturated zone. But, so far

  12. Tritium removal from air streams by catalytic oxidation and water adsorption

    International Nuclear Information System (INIS)

    Sherwood, A.E.

    1976-06-01

    An effective method of capturing tritium from air streams is by catalytic oxidation followed by water adsorption on a microporous solid adsorbent. Performance of a burner/dryer combination is illustrated by overall mass balance equations. Engineering design methods for packed bed reactors and adsorbers are reviewed, emphasizing the experimental data needed for design and the effect of operating conditions on system performance

  13. Galvanic detection of sulfur dioxide in ambient air at trace levels by anodic oxidation

    NARCIS (Netherlands)

    Lindqvist, F.

    1978-01-01

    A continuous method for the measurement of SO2 in ambient air at trace levels is described. The principle of detection is based on the anodic oxidation of SO2 in a galvanic cell. A differential measuring technique with a cell with two anodes and one cathode is used; background and noise current are

  14. Complex catalysts from self-repairing ensembles to highly reactive air-based oxidation systems

    Science.gov (United States)

    Craig L. Hill; Laurent Delannoy; Dean C. Duncan; Ira A. Weinstock; Roman F. Renneke; Richard S. Reiner; Rajai H. Atalla; Jong Woo Han; Daniel A. Hillesheim; Rui Cao; Travis M. Anderson; Nelya M. Okun; Djamaladdin G. Musaev; Yurii V. Geletii

    2007-01-01

    Progress in four interrelated catalysis research efforts in our laboratory are summarized: (1) catalytic photochemical functionalization of unactivated CeH bonds by polyoxometalates (POMs); (2) self-repairing catalysts; (3) catalysts for air-based oxidations under ambient conditions; and (4) terminal oxo complexes of the late-transition metal elements and their...

  15. Subcritical wet air oxidation of organic solvents and chelating agents of the nuclear fuel

    International Nuclear Information System (INIS)

    Bachir, Souley

    1999-01-01

    This document deals with the environment control, more specially organic solvents and chelating agents destruction, employed in the nuclear industry. This work details the subcritical wet air oxidation process. Another part of the document deals with the possible coupling between this process and the biodegradation technic in the framework of the sewage sludges treatment. (A.L.B.)

  16. Oxidative degradation of toluene and limonene in air by pulsed corona technology

    NARCIS (Netherlands)

    Hoeben, W.F.L.M.; Beckers, F.J.C.M.; Pemen, A.J.M.; Heesch, van E.J.M.; Kling, W.L.

    2012-01-01

    The oxidative degradation of two volatile organic compounds, i.e. toluene (fossil fuel based VOC) and limonene (biogenic VOC), has been studied. A hybrid pulsed power corona reactor with adjustable energy density has been utilized for degradation of ppm level target compounds in large air flows. The

  17. IN VITRO CARDIOTOXICITY OF AIR POLLUTION PARTICLES: ROLE OF BIOAVAILABLE CONSTITUENTS, OXIDATIVE STRESS AND TYROSINE PHOSPHORYLATION

    Science.gov (United States)

    IN VITRO CARDIOTOXICITY OF AIR POLLUTION PARTICLES: ROLE OF BIOAVAILABLE CONSTITUENTS, OXIDATIVE STRESS AND TYROSINE PHOSPHORYLATION.T. L. Knuckles1 R. Jaskot2, J. Richards2, and K.Dreher2.1Department of Molecular and Biomedical Sciences, College of Veterinary Medicin...

  18. Enhanced reversibility and durability of a solid oxide Fe-air redox battery by carbothermic reaction derived energy storage materials.

    Science.gov (United States)

    Zhao, Xuan; Li, Xue; Gong, Yunhui; Huang, Kevin

    2014-01-18

    The recently developed solid oxide metal-air redox battery is a new technology capable of high-rate chemistry. Here we report that the performance, reversibility and stability of a solid oxide iron-air redox battery can be significantly improved by nanostructuring energy storage materials from a carbothermic reaction.

  19. Effects of porosity and temperature on oxidation behavior in air of selected nuclear graphites

    International Nuclear Information System (INIS)

    Chen Dongyue; Li Zhengcao; Miao Wei; Zhang Zhengjun

    2012-01-01

    Nuclear graphite endures gas oxidation in High Temperature Gas-cooled Reactor (HTGR), which may threaten the safety of reactor. To study the oxidation behavior of nuclear graphite, weight loss curve is usually measured through Thermo Gravimetric Analysis (TGA) method. In this work, three brands of nuclear graphite for HTGR (i.e., HSM-SC, IG-11, and NBG-18) are oxidized under 873 and 1073 K in open air, and their weight loss curves are obtained. The acceleration of oxidizing rate is observed for both HSM-SC and IG-11, and is attributed to the large porosity increase during oxidation process. For HSM-SC, the porosity increase comes from preferential binder oxidation, and thus its binder quality shall be improved to obtain better oxidation resistance. Temperature effects on oxidation for HSM-SC are also studied, which shows that oxidizing gas tends to be exhausted at graphite surface at high temperature instead of penetrate into the interior of bulk. (author)

  20. Destabilization and dry-spot nucleation in thin liquid films on partially wetting substrates using a low-pressure air-jet

    NARCIS (Netherlands)

    Berendsen, C.W.J.; Zeegers, J.C.H.; Darhuber, A.A.

    2011-01-01

    The rupture of a thin liquid film on a partially wetting substrate can be initiated by external forces. In this manuscript we present experiments and numerical simulations of the effects of a laminar axisymmetric air-jet impinging on triethylene glycol films. We numerically calculate stagnation

  1. Study of the dynamics of the MoO2-Mo2C system for catalytic partial oxidation reactions

    Science.gov (United States)

    Cuba Torres, Christian Martin

    On a global scale, the energy demand is largely supplied by the combustion of non-renewable fossil fuels. However, their rapid depletion coupled with environmental and sustainability concerns are the main drivers to seek for alternative energetic strategies. To this end, the sustainable generation of hydrogen from renewable resources such as biodiesel would represent an attractive alternative solution to fossil fuels. Furthermore, hydrogen's lower environmental impact and greater independence from foreign control make it a strong contender for solving this global problem. Among a wide variety of methods for hydrogen production, the catalytic partial oxidation offers numerous advantages for compact and mobile fuel processing systems. For this reaction, the present work explores the versatility of the Mo--O--C catalytic system under different synthesis methods and reforming conditions using methyl oleate as a surrogate biodiesel. MoO2 exhibits good catalytic activity and exhibits high coke-resistance even under reforming conditions where long-chain oxygenated compounds are prone to form coke. Moreover, the lattice oxygen present in MoO2 promotes the Mars-Van Krevelen mechanism. Also, it is introduced a novel beta-Mo2C synthesis by the in-situ formation method that does not utilize external H2 inputs. Herein, the MoO 2/Mo2C system maintains high catalytic activity for partial oxidation while the lattice oxygen serves as a carbon buffer for preventing coke formation. This unique feature allows for longer operation reforming times despite slightly lower catalytic activity compared to the catalysts prepared by the traditional temperature-programmed reaction method. Moreover, it is demonstrated by a pulse reaction technique that during the phase transformation of MoO2 to beta-Mo2C, the formation of Mo metal as an intermediate is not responsible for the sintering of the material wrongly assumed by the temperature-programmed method.

  2. Hydrogen or synthesis gas production via the partial oxidation of methane over supported nickel-cobalt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Alaric C.W. [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Institute of Chemical and Engineering Sciences, 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Chen, Luwei; Lin, Jianyi [Institute of Chemical and Engineering Sciences, 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Kee Leong, Weng [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Johnson, Brian F.G.; Khimyak, Tetyana [University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, UK CB2 1EW (United Kingdom)

    2007-05-15

    Activity, selectivity, and coking-resistance of a series of Ni{sub x}Co{sub y} (where x,y are the respective metal loadings of 0, 1, 2 or 3 wt.%; x+y=3) bimetallic catalysts supported on CaAl{sub 2}O{sub 4}/Al{sub 2}O{sub 3} have been studied for hydrogen/synthesis gas production via the catalytic partial oxidation (CPO) of methane. Catalysts were characterized by temperature programmed reduction (TPR), transmission electron microscopy (TEM) and X-ray fluorescence multi-element analysis (XRF). Their activity for the partial oxidation of methane to hydrogen and carbon monoxide (at 1 bar, gas hourly space velocity (GHSV) of 144,000cm{sup 3}g{sup -1}h{sup -1} and CH{sub 4}/O{sub 2} molar ratio of 2) was investigated, and coke deposited on the spent catalysts was studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and thermogravimetric analysis (TGA). The activity was found to decrease in the order of Ni{sub 2}Co>Ni{sub 3}>NiCo{sub 2}>>Co{sub 3}, while CO and H{sub 2} selectivities were found to be in the order ofNi{sub 2}Co>Ni{sub 3}{approx}NiCo{sub 2}>Co{sub 3}. Ni{sub 2}Co is also shown to be more resistant to coking as compared to Ni{sub 3}, which is a current catalyst of choice. Results show that not only does Ni{sub 2}Co have the highest activity and selectivity among all the catalysts tested, it is also relatively resistant to coking. This finding would be helpful for catalyst design to achieve high coking resistivity catalysts for hydrogen production from CPO of methane. (author)

  3. Reaction phenomena of catalytic partial oxidation of methane under the impact of carbon dioxide addition and heat recirculation

    International Nuclear Information System (INIS)

    Chen, Wei-Hsin; Lin, Shih-Cheng

    2015-01-01

    The reaction phenomena of CPOM (catalytic partial oxidation of methane) in a Swiss-roll reactor are studied numerically where a rhodium-based catalyst bed is embedded at the center of the reactor. CO 2 is added into the feed gas and excess enthalpy recovery is performed to evaluate their influences on CPOM performance. In the study, the mole ratio of O 2 to CH 4 (O 2 /CH 4 ratio) is fixed at 0.5 and the mole ratio of CO 2 to O 2 (CO 2 /O 2 ratio) is in the range of 0–2. The results reveal that CO 2 addition into the influent has a slight effect on methane combustion, but significantly enhances dry reforming and suppresses steam reforming. The reaction extents of steam reforming and dry reforming in CPOM without heat recovery and CO 2 addition are in a comparable state. Once CO 2 is added into the feed gas, the dry reforming is enhanced, thereby dominating CH 4 consumption. Compared to the reactor without excess enthalpy recovery, heat recirculation drastically increases the maximum reaction temperature and CH 4 conversion in the catalyst bed; it also intensifies the H 2 selectivity, H 2 yield, CO 2 conversion, and syngas production rate. The predictions indicate that the heat recirculation is able to improve the syngas formation up to 45%. - Highlights: • Catalytic partial oxidation of methane with CO 2 addition and heat recovery is studied. • CO 2 addition has a slight effect on methane combustion. • CO 2 addition significantly enhances dry reforming and suppresses steam reforming. • Dry reforming dominates CH 4 consumption when CO 2 addition is large. • Heat recirculation can improve the syngas formation up to 45%

  4. Partial oxidation of D-xylose to maleic anhydride and acrylic acid over vanadyl pyrophosphate

    International Nuclear Information System (INIS)

    Ghaznavi, Touraj; Neagoe, Cristian; Patience, Gregory S.

    2014-01-01

    Xylose is the second most abundant sugar after glucose. Despite its tremendous potential to serve as a renewable feedstock, few commercial processes exploit this resource. Here, we report a new technology in which a two-fluid nozzle atomizes a xylose-water solution into a capillary fluidized bed operating above 300 °C. Xylose-water droplets form at the tip of the injector, vaporize then react with a heterogeneous mixed oxide catalyst. A syringe pump metered the solution to the reactor charged with 1 g of catalyst. Product yield over vanadyl pyrophosphate was higher compared to molybdenum trioxide-cobalt oxide and iron molybdate; it reached 25% for maleic anhydride, 17% for acrylic acid and 11% for acrolein. Gas residence time was 0.2 s. The catalyst was free of coke even after operating for 4 h – based on a thermogravimetric analysis of catalyst withdrawn from the reactor. Below 300 °C, powder agglomerated at the tip of the injector at 300 °C; it also agglomerated with a xylose mass fraction of 7% in water. - Highlights: • D-xylose reacts to form maleic anhydride and acrylic acid above 250 °C. • Vanadyl pyrophosphate is both active and selective for maleic and acrylic acid. • Acid and acrolein yield approaches 50% for a xylose mass fraction of 3% in water. • Catalyst agglomerates at low temperatures and high xylose aqueous mass fraction. • Atomization quality is a determining factor to minimize agglomeration

  5. Commonly used air filters fail to eliminate secondhand smoke induced oxidative stress and inflammatory responses.

    Science.gov (United States)

    Muthumalage, Thivanka; Pritsos, Karen; Hunter, Kenneth; Pritsos, Chris

    2017-07-01

    Secondhand smoke (SHS) causes approximately 50,000 deaths per year. Despite all the health warnings, smoking is still allowed indoors in many states exposing both workers and patrons to SHS on a daily basis. The opponents of smoking bans suggest that present day air filtration systems remove the health hazards of exposure to SHS. In this study, using an acute SHS exposure model, we looked at the impact of commonly used air filters (MERV-8 pleated and MERV-8 pleated activated charcoal) on SHS by assessing the inflammatory response and the oxidative stress response in C57BL/6 mice. In order to assess the inflammatory response, we looked at the tumor necrosis factor alpha (TNF-α) cytokine production by alveolar macrophages (AMs), and for the oxidative response, we quantified the products of lipid peroxidation and the total glutathione (tGSH) production in lung homogenates. Our results showed that SHS caused significant immune and oxidative stress responses. The tested filters resulted in only a modest alleviation of inflammatory and oxidative responses due to SHS exposure. Our data show that these air filters cannot eliminate the risk of SHS exposure and that a short-term exposure to SHS is sufficient to alter the inflammatory cytokine response and to initiate a complex oxidative stress response. Our results are consistent with the statement made by the Surgeon General's reports that there is no risk free level of exposure to SHS.

  6. Uranium Metal to Oxide Conversion by Air Oxidation –Process Development

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, A

    2001-12-31

    Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

  7. Oxidation characteristics of MgF2 in air at high temperature

    Science.gov (United States)

    Chen, H. K.; Jie, Y. Y.; Chang, L.

    2017-02-01

    High temperature oxidation properties of MgF2 in air were studied. The changes of phase composition, macro surface morphology, weight and elemental composition of MgF2 samples with temperature were investigated by using XRD, EDS and gravimetric analyses. The results show that the oxidation reaction of MgF2 converted to MgO occurred at high temperature, and the reaction was accelerated by the increase of temperature and the presence of impurities. This result clarifies the understanding of the high temperature oxidation behavior of MgF2 in air, and provides a theoretical basis for the reasonable application of MgF2 in optical coating materials, electronic ceramic materials and magnesium melt protection.

  8. Oxidation/volatilization rates in air for candidate fusion reactor blanket materials, PCA and HT-9

    International Nuclear Information System (INIS)

    Piet, S.J.; Kraus, H.G.; Neilson, R.M. Jr.; Jones, J.L.

    1986-01-01

    Large uncertainties exist in the quantity of neutron-induced activation products that can be mobilized in potential fusion accidents. The accidental combination of high temperatures and oxidizing conditions might lead to mobilization of a significant amount of activation products from structural materials. Here, the volatilization of constituents of PCA and HT-9 resulting from oxidation in air was investigated. Tests were conducted in flowing air at temperatures from 600 to 1300 0 C for 1, 5, or 20 h. Elemental volatility was calculated in terms of the weight fraction of the element volatilized from the initial alloy. Molybdenum and manganese were the radiologically significant primary constituents most volatilizized, suggesting that molybdenum and manganese should be minimized in fusion steel compositions. Higher chromium content appears beneficial in reducing hazards from mobile activation products. Scanning electron microscopy and energy dispersive spectroscopy were used to study the oxide layer on samples. (orig.)

  9. Oxidation/volatilization rates in air for candidate fusion reactor blanket materials, PCA and HT-9

    International Nuclear Information System (INIS)

    Piet, S.J.; Kraus, H.G.; Neilson, R.M. Jr.; Jones, J.L.

    1986-01-01

    Large uncertainties exist in the quantity of neutron-induced activation products that can be mobilized in potential fusion accidents. The accidental combination of high temperatures and oxidizing conditions might lead to mobilization of a significant amount of activation products from structural materials. Here, the volatilization of constituents of PCA and HT-9 resulting from oxidation in air was investigated. Tests were conducted in flowing air at temperatures from 600 to 1300 0 C for 1, 5, or 20 hours. Elemental volatility was calculated in terms of the weight fraction of the element volatilized from the initial alloy. Molybdenum and manganese were the radiologically significant primary constituents most volatilized, suggesting that molybdenum and manganese should be minimized in fusion steel compositions. Higher chromium content appears beneficial in reducing hazards from mobile activation products. Scanning electron microscopy and energy dispersive spectroscopy were used to study the oxide layer on samples

  10. Startup and operating characteristics of an external air-lift reflux partial nitritation-ANAMMOX integrative reactor.

    Science.gov (United States)

    Li, Xiang; Huang, Yong; Yuan, Yi; Bi, Zhen; Liu, Xin

    2017-08-01

    The differences in the physiological characteristics between AOB and ANAMMOX bacteria lead to suboptimal performance when used in a single reactor. In this study, aerobic and anaerobic zones with different survival environments were constructed in a single reactor to realize partitioned culture of AOB and ANAMMOX bacteria. An external air-lift reflux system was formed which used the exhaust from the aeration zone as power to return the effluent to the aeration zone. The reflux system effectively alleviated the large pH fluctuations and promoted NO 2 - -N to rapidly use by ANAMMOX bacteria, effectively inhibiting the activity of NOB. After 95d of running, the nitrogen removal rate increased from the initial 0.21kg/(m 3 ·d) to 3.1kg/(m 3 ·d). FISH analyses further demonstrated that AOB and ANAMMOX bacteria acquired efficient enrichment in the corresponding zone. Thus, this type of integrative reactor may create the environments needed for the partial nitritation-ANAMMOX processing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Excellent performance of Pt-C/TiO2 for methanol oxidation: Contribution of mesopores and partially coated carbon

    Science.gov (United States)

    Wu, Xinbing; Zhuang, Wei; Lu, Linghong; Li, Licheng; Zhu, Jiahua; Mu, Liwen; Li, Wei; Zhu, Yudan; Lu, Xiaohua

    2017-12-01

    Partial deposition of carbon onto mesoporous TiO2 (C/TiO2) were prepared as supporting substrate for Pt catalyst development. Carbon deposition is achieved by in-situ carbonization of furfuryl alcohol. The hybrid catalysts were characterized by XRD, Raman, SEM and TEM and exhibited outstanding catalytic activity and stability in methanol oxidation reaction. The heterogeneous carbon coated on mesoporous TiO2 fibers provided excellent electrical conductivity and strong interfacial interaction between TiO2 support and Pt metal nanoparticles. Methanol oxidation reaction results showed that the activity of Pt-C/TiO2 is 3.0 and 1.5 times higher than that of Pt-TiO2 and Pt-C, respectively. In addition, the Pt-C/TiO2 exhibited a 6.7 times enhanced stability compared with Pt-C after 2000 cycles. The synergistic effect of C/TiO2 is responsible for the enhanced activity of Pt-C/TiO2, and its excellent durability could be ascribed to the strong interfacial interaction between Pt nanoparticles and C/TiO2 support.

  12. Effect of systemic nitric oxide synthase inhibition on optic disc oxygen partial pressure in normoxia and in hypercapnia.

    Science.gov (United States)

    Petropoulos, Ioannis K; Pournaras, Jean-Antoine C; Stangos, Alexandros N; Pournaras, Constantin J

    2009-01-01

    To investigate the effect of systemic nitric oxide synthase (NOS) inhibition on optic disc oxygen partial pressure (PO(2)) in normoxia and hypercapnia. Intervascular optic disc PO(2) was measured in 12 anesthetized minipigs by using oxygen-sensitive microelectrodes placed 0.1), despite a 21% increase of mean arterial pressure. Optic disc PO(2) increase under hypercapnia was blunted after L-NAME injection (DeltaPO(2) = 0.6 +/- 1.1 mm Hg; 3%; P > 0.1), and this effect was reversible by L-arginine. Moreover, L-NAME reduced the response to carbogen by 29% (DeltaPO(2) = 9.1 +/- 4.4 mm Hg; 49%; P = 0.01 versus before L-NAME). The response to hyperoxia was not affected. Whereas systemic NOS inhibition did not affect optic disc PO(2) in normoxia, a blunting effect was noted on the CO(2)-induced optic disc PO(2) increase. Nitric oxide appears to mediate the hypercapnic optic disc PO(2) increase.

  13. Catalytic Activity Studies of Vanadia/Silica–Titania Catalysts in SVOC Partial Oxidation to Formaldehyde: Focus on the Catalyst Composition

    Directory of Open Access Journals (Sweden)

    Niina Koivikko

    2018-02-01

    Full Text Available In this work, silica–titania supported catalysts were prepared by a sol–gel method with various compositions. Vanadia was impregnated on SiO2-TiO2 with different loadings, and materials were investigated in the partial oxidation of methanol and methyl mercaptan to formaldehyde. The materials were characterized by using N2 physisorption, X-ray diffraction (XRD, X-ray fluorescence spectroscopy (XRF, X-ray photoelectron spectroscopy (XPS, Scanning transmission electron microscope (STEM, NH3-TPD, and Raman techniques. The activity results show the high importance of an optimized SiO2-TiO2 ratio to reach a high reactant conversion and formaldehyde yield. The characteristics of mixed oxides ensure a better dispersion of the active phase on the support and in this way increase the activity of the catalysts. The addition of vanadium pentoxide on the support lowered the optimal temperature of the reaction significantly. Increasing the vanadia loading from 1.5% to 2.5% did not result in higher formaldehyde concentration. Over the 1.5%V2O5/SiO2 + 30%TiO2 catalyst, the optimal selectivity was reached at 415 °C when the maximum formaldehyde concentration was ~1000 ppm.

  14. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Smolik, Galen Richard; Petti, David Andrew; Sharpe, John Phillip; Schuetz, Stanley Thomas

    2000-10-01

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200°C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices

  15. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Smolik, G.R.; Petti, D.A.; Sharpe, J.P.; Schuetz, S.T.

    2000-10-31

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.

  16. Calculation of gas-flow in plasma reactor for carbon partial oxidation

    Science.gov (United States)

    Bespala, Evgeny; Myshkin, Vyacheslav; Novoselov, Ivan; Pavliuk, Alexander; Makarevich, Semen; Bespala, Yuliya

    2018-03-01

    The paper discusses isotopic effects at carbon oxidation in low temperature non-equilibrium plasma at constant magnetic field. There is described routine of experiment and defined optimal parameters ensuring maximum enrichment factor at given electrophysical, gas-dynamic, and thermodymanical parameters. It has been demonstrated that at high-frequency generator capacity of 4 kW, supply frequency of 27 MHz and field density of 44 mT the concentration of paramagnetic heavy nuclei 13C in gaseous phase increases up to 1.78 % compared to 1.11 % for natural concentration. Authors explain isotopic effect decrease during plasmachemical separation induced by mixing gas flows enriched in different isotopes at the lack of product quench. With the help of modeling the motion of gas flows inside the plasma-chemical reactor based on numerical calculation of Navier-Stokes equation authors determine zones of gas mixing and cooling speed. To increase isotopic effects and proportion of 13C in gaseous phase it has been proposed to use quench in the form of Laval nozzle of refractory steel. The article represents results on calculation of optimal Laval Nozzle parameters for plasma-chemical reactor of chosen geometry of. There are also given dependences of quench time of products on pressure at the diffuser output and on critical section diameter. Authors determine the location of quench inside the plasma-chemical reactor in the paper.

  17. Sea-to-air and diapycnal nitrous oxide fluxes in the eastern tropical North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    A. Kock

    2012-03-01

    Full Text Available Sea-to-air and diapycnal fluxes of nitrous oxide (N2O into the mixed layer were determined during three cruises to the upwelling region off Mauritania. Sea-to-air fluxes as well as diapycnal fluxes were elevated close to the shelf break, but elevated sea-to-air fluxes reached further offshore as a result of the offshore transport of upwelled water masses. To calculate a mixed layer budget for N2O we compared the regionally averaged sea-to-air and diapycnal fluxes and estimated the potential contribution of other processes, such as vertical advection and biological N2O production in the mixed layer. Using common parameterizations for the gas transfer velocity, the comparison of the average sea-to-air and diapycnal N2O fluxes indicated that the mean sea-to-air flux is about three to four times larger than the diapycnal flux. Neither vertical and horizontal advection nor biological production were found sufficient to close the mixed layer budget. Instead, the sea-to-air flux, calculated using a parameterization that takes into account the attenuating effect of surfactants on gas exchange, is in the same range as the diapycnal flux. From our observations we conclude that common parameterizations for the gas transfer velocity likely overestimate the air-sea gas exchange within highly productive upwelling zones.

  18. One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

    OpenAIRE

    Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

    2015-01-01

    Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanof...

  19. Partial oxidation of methane to syngas on Rh/Al{sub 2}O{sub 3} and Rh/Ce-ZrO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Raquel L.; Bitencourt, Isabela G.; Passos, Fabio B., E-mail: fbpassos@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Quimica e Petroleo

    2013-01-15

    The partial oxidation of methane with {gamma}-Al{sub 2}O{sub 3}-, CeO{sub 2}-, ZrO{sub 2}- and Ce-ZrO{sub 2}-supported rhodium catalysts was investigated. DRIFTS (diffuse reflectance infrared spectroscopy) measurements of adsorbed CO showed the formation of different rhodium species on different supports, which influenced the dispersion of the metal. The effects of the metal dispersion, oxygen storage capacity on the activity of these catalysts for the partial oxidation of methane are discussed. (author)

  20. Lycium barbarum (wolfberry reduces secondary degeneration and oxidative stress, and inhibits JNK pathway in retina after partial optic nerve transection.

    Directory of Open Access Journals (Sweden)

    Hongying Li

    Full Text Available Our group has shown that the polysaccharides extracted from Lycium barbarum (LBP are neuroprotective for retinal ganglion cells (RGCs in different animal models. Protecting RGCs from secondary degeneration is a promising direction for therapy in glaucoma management. The complete optic nerve transection (CONT model can be used to study primary degeneration of RGCs, while the partial optic nerve transection (PONT model can be used to study secondary degeneration of RGCs because primary degeneration of RGCs and secondary degeneration can be separated in location in the same retina in this model; in other situations, these types of degeneration can be difficult to distinguish. In order to examine which kind of degeneration LBP could delay, both CONT and PONT models were used in this study. Rats were fed with LBP or vehicle daily from 7 days before surgery until sacrifice at different time-points and the surviving numbers of RGCs were evaluated. The expression of several proteins related to inflammation, oxidative stress, and the c-jun N-terminal kinase (JNK pathways were detected with Western-blot analysis. LBP did not delay primary degeneration of RGCs after either CONT or PONT, but it did delay secondary degeneration of RGCs after PONT. We found that LBP appeared to exert these protective effects by inhibiting oxidative stress and the JNK/c-jun pathway and by transiently increasing production of insulin-like growth factor-1 (IGF-1. This study suggests that LBP can delay secondary degeneration of RGCs and this effect may be linked to inhibition of oxidative stress and the JNK/c-jun pathway in the retina.

  1. Lycium Barbarum (Wolfberry) Reduces Secondary Degeneration and Oxidative Stress, and Inhibits JNK Pathway in Retina after Partial Optic Nerve Transection

    Science.gov (United States)

    Li, Hongying; Liang, Yuxiang; Chiu, Kin; Yuan, Qiuju; Lin, Bin; Chang, Raymond Chuen-Chung; So, Kwok-Fai

    2013-01-01

    Our group has shown that the polysaccharides extracted from Lycium barbarum (LBP) are neuroprotective for retinal ganglion cells (RGCs) in different animal models. Protecting RGCs from secondary degeneration is a promising direction for therapy in glaucoma management. The complete optic nerve transection (CONT) model can be used to study primary degeneration of RGCs, while the partial optic nerve transection (PONT) model can be used to study secondary degeneration of RGCs because primary degeneration of RGCs and secondary degeneration can be separated in location in the same retina in this model; in other situations, these types of degeneration can be difficult to distinguish. In order to examine which kind of degeneration LBP could delay, both CONT and PONT models were used in this study. Rats were fed with LBP or vehicle daily from 7 days before surgery until sacrifice at different time-points and the surviving numbers of RGCs were evaluated. The expression of several proteins related to inflammation, oxidative stress, and the c-jun N-terminal kinase (JNK) pathways were detected with Western-blot analysis. LBP did not delay primary degeneration of RGCs after either CONT or PONT, but it did delay secondary degeneration of RGCs after PONT. We found that LBP appeared to exert these protective effects by inhibiting oxidative stress and the JNK/c-jun pathway and by transiently increasing production of insulin-like growth factor-1 (IGF-1). This study suggests that LBP can delay secondary degeneration of RGCs and this effect may be linked to inhibition of oxidative stress and the JNK/c-jun pathway in the retina. PMID:23894366

  2. Ozone decomposition kinetics on alumina: effects of ozone partial pressure, relative humidity and repeated oxidation cycles

    Directory of Open Access Journals (Sweden)

    R. C. Sullivan

    2004-01-01

    Full Text Available The room temperature kinetics of gas-phase ozone loss via heterogeneous interactions with thin alumina films has been studied in real-time using 254nm absorption spectroscopy to monitor ozone concentrations. The films were prepared from dispersions of fine alumina powder in methanol and their surface areas were determined by an in situ procedure using adsorption of krypton at 77K. The alumina was found to lose reactivity with increasing ozone exposure. However, some of the lost reactivity could be recovered over timescales of days in an environment free of water, ozone and carbon dioxide. From multiple exposures of ozone to the same film, it was found that the number of active sites is large, greater than 1.4x1014 active sites per cm2 of surface area or comparable to the total number of surface sites. The films maintain some reactivity at this point, which is consistent with there being some degree of active site regeneration during the experiment and with ozone loss being catalytic to some degree. The initial uptake coefficients on fresh films were found to be inversely dependent on the ozone concentration, varying from roughly 10-6 for ozone concentrations of 1014 molecules/cm3 to 10-5 at 1013 molecules/cm3. The initial uptake coefficients were not dependent on the relative humidity, up to 75%, within the precision of the experiment. The reaction mechanism is discussed, as well as the implications these results have for assessing the effect of mineral dust on atmospheric oxidant levels.

  3. Rh(iii)-catalyzed C-H olefination of N-pentafluoroaryl benzamides using air as the sole oxidant.

    Science.gov (United States)

    Lu, Yi; Wang, Huai-Wei; Spangler, Jillian E; Chen, Kai; Cui, Pei-Pei; Zhao, Yue; Sun, Wei-Yin; Yu, Jin-Quan

    2015-03-01

    The oxidative olefination of a broad array of arenes and heteroarenes with a variety of activated and unactivated olefins has be achieved via a rhodium(iii)-catalyzed C-H activation reaction. The use of an N -pentafluorophenyl benzamide directing group is crucial for achieving catalytic turnovers in the presence of air as the sole oxidant without using a co-oxidant.

  4. A DRIFTS study of the partial oxidation of ethanol on Rh catalysts; Estudo da oxidacao parcial do etanol em catalisadores de Rh por DRIFTS

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Raquel Lima; Passos, Fabio Barboza, E-mail: fbpassos@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Departamento de Engenharia Quimica e de Petroleo

    2013-09-01

    The partial oxidation of ethanol on {gamma}-Al{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2} and Ce{sub x}Zr{sub 1-x}O{sub 2} supported rhodium catalysts was investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The catalysts were characterized by temperature-programmed reduction (TPR) and cyclohexane dehydrogenation. DRIFTS studies on the partial oxidation of ethanol showed that ethanol is adsorbed dissociatively, through O-H bond breaking, with the formation of ethoxy species, followed by successive dehydrogenation to acetaldehyde and acetyl species. Further oxidation to acetate and carbonate species lead to the formation of CO, CH{sub 4} and H{sub 2} by decomposition. The presence of CeO{sub 2} in the catalysts favored the oxidation steps due to its oxygen storage capacity. (author)

  5. High temperature mechanisms and kinetics of SiC oxidation under low partial pressures of oxygen: application to the fuel cladding of gas fast reactors

    International Nuclear Information System (INIS)

    Hun, N.

    2011-01-01

    Gas Fast Reactor (GFR) is one of the different Generation IV concepts under investigation for energy production. SiC/SiC composites are candidates of primary interest for a GFR fuel cladding use, thanks to good corrosion resistance among other properties. The mechanisms and kinetics of SiC oxidation under operating conditions have to be identified and quantified as the corrosion can decrease the mechanical properties of the composite. An experimental device has been developed to study the oxidation of silicon carbide under high temperature and low oxygen partial pressure. The results pointed out that not only parabolic oxidation, but also interfacial reactions and volatilization occur under such conditions. After determining the kinetics of each mechanism, as functions of oxygen partial pressure and temperature, the data are used for the modeling of the composites oxidation. The model will be used to predict the lifetime of the composite in operating conditions. (author) [fr

  6. Air

    International Nuclear Information System (INIS)

    Gugele, B.; Scheider, J.; Spangl, W.

    2001-01-01

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  7. Role of oxidative stress in cardiovascular disease outcomes following exposure to ambient air pollution.

    Science.gov (United States)

    Kelly, Frank J; Fussell, Julia C

    2017-09-01

    Exposure to ambient air pollution is associated with adverse cardiovascular outcomes. These are manifested through several, likely overlapping, pathways including at the functional level, endothelial dysfunction, atherosclerosis, pro-coagulation and alterations in autonomic nervous system balance and blood pressure. At numerous points within each of these pathways, there is potential for cellular oxidative imbalances to occur. The current review examines epidemiological, occupational and controlled exposure studies and research employing healthy and diseased animal models, isolated organs and cell cultures in assessing the importance of the pro-oxidant potential of air pollution in the development of cardiovascular disease outcomes. The collective body of data provides evidence that oxidative stress (OS) is not only central to eliciting specific cardiac endpoints, but is also implicated in modulating the risk of succumbing to cardiovascular disease, sensitivity to ischemia/reperfusion injury and the onset and progression of metabolic disease following ambient pollution exposure. To add to this large research effort conducted to date, further work is required to provide greater insight into areas such as (a) whether an oxidative imbalance triggers and/or worsens the effect and/or is representative of the consequence of disease progression, (b) OS pathways and cardiac outcomes caused by individual pollutants within air pollution mixtures, or as a consequence of inter-pollutant interactions and (c) potential protection provided by nutritional supplements and/or pharmacological agents with antioxidant properties, in susceptible populations residing in polluted urban cities. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  8. Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

    DEFF Research Database (Denmark)

    Poreddy, Raju; Engelbrekt, Christian; Riisager, Anders

    2015-01-01

    The oxidative dehydrogenation of alcohols to carbonyl compounds was studied using CuO nanoparticle catalysts prepared by solution synthesis in buffered media. CuO nanoparticles synthesized in N-cyclohexyl- 3-aminopropanesulfonic acid buffer showed high catalytic activity for the oxidation...... of benzylic, alicyclic and unsaturated alcohols to their corresponding carbonyl compounds with excellent selectivities. The observed trend in activity for conversion of substituted alcohols suggested a β-H elimination step to be involved, thus enabling a possible reaction mechanism for oxidative...... dehydrogenation of benzyl alcohols to be proposed. The use of CuO as an inexpensive and efficient heterogeneous catalyst under aerobic conditions provides a new noble metal-free and green reaction protocol for carbonyl compound synthesis....

  9. Oxidation capacity of the city air of Santiago, Chile

    Directory of Open Access Journals (Sweden)

    Y. F. Elshorbany

    2009-03-01

    Full Text Available The oxidation capacity of the highly polluted urban area of Santiago, Chile has been evaluated during a summer measurement campaign carried out from 8–20 March 2005. The hydroxyl (OH radical budget was evaluated employing a simple quasi-photostationary-state model (PSS constrained with simultaneous measurements of HONO, HCHO, O3, NO, NO2, j(O1D, j(NO2, 13 alkenes and meteorological parameters. In addition, a zero dimensional photochemical box model based on the Master Chemical Mechanism (MCMv3.1 has been used to estimate production rates and total free radical budgets, including OH, HO2 and RO2. Besides the above parameters, the MCM model has been constrained by the measured CO and volatile organic compounds (VOCs including alkanes and aromatics. Both models simulate the same OH concentration during daytime indicating that the primary OH sources and sinks included in the simple PSS model predominate. Mixing ratios of the main OH radical precursors were found to be in the range 0.8–7 ppbv (HONO, 0.9–11 ppbv (HCHO and 0–125 ppbv (O3. The alkenes average mixing ratio was ~58 ppbC accounting for ~12% of the total identified non-methane hydrocarbons (NMHCs. During the daytime (08:00 h–19:00 h, HONO photolysis was shown to be the most important primary OH radical source comprising alone ~55% of the total initial production rate, followed by alkene ozonolysis (~24% and photolysis of HCHO (~16% and O3 (~5%. The calculated average and maximum daytime OH production rates from HONO photolysis was 1.7 ppbv h−1 and 3.1 ppbv h−1, respectively. Based on the experimental results a strong photochemical daytime source of HONO is proposed. A detailed analysis of the sources of OH radical precursors has also been carried out.

  10. Air-electron stream interactions during magnetic resonance IGRT : Skin irradiation outside the treatment field during accelerated partial breast irradiation.

    Science.gov (United States)

    Park, Jong Min; Shin, Kyung Hwan; Kim, Jung-In; Park, So-Yeon; Jeon, Seung Hyuck; Choi, Noorie; Kim, Jin Ho; Wu, Hong-Gyun

    2018-01-01

    To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm 2 , respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field.

  11. The Measurement of Fuel-Air Ratio by Analysis for the Oxidized Exhaust Gas

    Science.gov (United States)

    Gerrish, Harold C.; Meem, J. Lawrence, Jr.

    1943-01-01

    An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs for the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124.

  12. The Measurement of Fuel-air Ratio by Analysis of the Oxidized Exhaust Gas

    Science.gov (United States)

    Memm, J. Lawrence, Jr.

    1943-01-01

    An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy Fuel Specification, No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs or the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124

  13. Air injection low temperature oxidation process for enhanced oil recovery from light oil reservoirs

    International Nuclear Information System (INIS)

    Tunio, A.H.; Harijan, K.

    2010-01-01

    This paper represents EOR (Enhanced Oil Recovery) methods to recover unswept oil from depleted light oil reservoirs. The essential theme here is the removal of oxygen at LTO (Low Temperature Oxidation) from the injected air for a light oil reservoir by means of some chemical reactions occurring between oil and oxygen. In-situ combustion process, HTO (High Temperature Oxidation) is not suitable for deep light oil reservoirs. In case of light oil reservoirs LTO is more suitable to prevail as comparative to HTO. Few laboratory experimental results were obtained from air injection process, to study the LTO reactions. LTO process is suitable for air injection rate in which reservoir has sufficiently high temperature and spontaneous reaction takes place. Out comes of this study are the effect of LTO reactions in oxygen consumption and the recovery of oil. This air injection method is economic compared to other EOR methods i.e. miscible hydrocarbon gas, nitrogen, and carbon dioxide flooding etc. This LTO air injection process is suitable for secondary recovery methods where water flooding is not feasible due to technical problems. (author)

  14. High temperature oxidation characteristics of developed Ni-Cr-W superalloys in air

    International Nuclear Information System (INIS)

    Suzuki, Tomio; Shindo, Masami

    1996-11-01

    For expanding utilization of the Ni-Cr-W superalloy, which has been developed as one of new high temperature structural materials used in the advanced High Temperature Gas-cooled Reactors (HTGRs), in various engineering fields including the structural material for heat utilization system, the oxidation behavior of this alloy in air as one of high oxidizing environments becomes one of key factors. The oxidation tests for the industrial scale heat of Ni-Cr-W superalloy with the optimized chemical composition and five kinds of experimental Ni-Cr-W alloys with different Cr/W ratio were carried out at high temperatures in the air compared with Hastelloy XR. The conclusions were obtained as follows. (1) The oxidation resistance of the industrial scale heat of Ni-Cr-W superalloy with the optimized chemical composition was superior to that of Hastelloy XR. (2) The most excellent oxidation resistance was obtained in an alloy with 19% Cr of the industrial scale heat of Ni-Cr-W superalloy. (author)

  15. Platinum Catalysts Supported on Ce, Zr, Pr - Oxides in Catalytic Wet Air Oxidation of Acetic Acid

    Czech Academy of Sciences Publication Activity Database

    Mikulová, Jana; Rossignol, S.; Barbier Jr., J.; Duprez, D.; Kappenstein, C.

    2007-01-01

    Roč. 146, č. 3 (2007), s. 1248-1253 ISSN 0304-3894 Institutional research plan: CEZ:AV0Z40720504 Keywords : platinum * cerium oxide * carbonate species Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.337, year: 2007

  16. High temperature cyclic oxidation of Ti-Al based intermetallic in static laboratory air

    International Nuclear Information System (INIS)

    Astuty Amrin; Esah Hamzah; Nurfashahidayu Mohd Badri; Hafida Hamzah

    2007-01-01

    The objective of this study is to investigate the oxidation behaviour of binary γ-Ti Al based intermetallics with composition (at%) of 45A, 48Al and 50 Al, and ternary alloys of Ti-48Al containing 2Cr and 4Cr. Thermal cyclic oxidation was conducted discontinuously at temperatures of 700 degree Celsius and 900 degree Celsius in static laboratory air. Optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and X-ray diffraction (XRD) techniques were employed for the analysis. SEM examination of cross-sectional samples using secondary electron and line-scan analysis after exposure at 700 degree Celsius showed that non-adherent oxides scales formed due to the spallation caused by cyclic condition. For exposure to 900 degree Celsius, only binary alloys exhibited breakaway oxidation whereas the oxide scales formed on the ternary alloys were well-adhered on the substrate alloy. Overall, exposure at 900 degree Celsius resulted in thicker and harder oxide scales and addition of Cr seems to improve oxidation resistance of Ti-Al based intermetallics at higher temperature. (author)

  17. Oxidation Behavior of Simudated Metallic U-Nb Alloys in Air

    International Nuclear Information System (INIS)

    Lee, Eun Pyo; Ju, June Sik; You, Gil Sung; Cho, Il Je; Kook, Dong Hak; Kim, Ho Dong

    2004-01-01

    In order to enhance an oxidation resistance of the pure uranium metal under air condition, a small quantity of niobium(Nb) which is known to mitigate metal oxidation is added into uranium metal as an alloying element. A simulated metallic uranium alloy, U-Nb has been fabricated and then oxidized in the range of 200 to under the environment of the pure oxygen gas. The oxidized quantity in terms of the weight gain (wt%) has been measured with the help of a thermogravimetric analyzer. The results show that the oxidation resistance of the U-Nb alloy is considerably enhanced in comparison with that of the pure uranium metal. It is revealed that the oxidation resistance of the former with the niobium content of 1, 2, 3, and 4 wt% is : 1) 1.61, 7.78, 11.76 and 20.14 times at the temperature of 200 .deg. C; 2) 1.45, 5.98, 10.08 and 11.15 times at 250 .deg. C; and 3) 1.33, 4.82, 8.87 and 6.84 times at 300 .deg. C higher than that of the latter, respectively. Besides, it is shown that the activation energy attributable to the oxidation is 17.13-21.92 kcal/mol.

  18. Influence of air flow rate on structural and electrical properties of undoped indium oxide thin films

    International Nuclear Information System (INIS)

    Mirzapour, S.; Rozati, S.M.; Takwale, M.G.; Marathe, B.R.; Bhide, V.G.

    1993-01-01

    Using the spray pyrolysis technique thin films of indium oxide were prepared on Corning glass (7059) at a substrate temperature of 425 C at different flow rates. The electrical and structural properties of these films were studied. The Hall measurements at room temperature showed that the films prepared in an air flow rate of 7 litre min -1 have the highest mobility of 47 cm 2 V -1 s -1 and a minimum resistivity of 1.125 x 10 -3 Ω cm. The X-ray diffraction patterns showed that the films have a preferred orientation of [400] which peaks at the air flow rate of 7 litre min -1 . (orig.)

  19. Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress-Induced DNA Damage

    DEFF Research Database (Denmark)

    Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter

    2007-01-01

    mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. DESIGN. Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking...... exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. METHODS: The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were...

  20. Oxidation of U-20 at% Zr alloy in air at 423-1063 K

    International Nuclear Information System (INIS)

    Matsui, Tsuneo; Yamada, Takanobu; Ikai, Yasushi; Naito, Keiji

    1993-01-01

    The oxidation behavior of U 0.80 Zr 0.20 alloy (two-phase mixture of U and UZr 2 below 878 K and single solid solution above 1008 K) was studied by thermogravimetry in the temperature range from 423 to 1063 K in air. During oxidation in the low temperature region (423-503 K), the sample kept its initial shape (a rectangular rod) and the surface of the sample was covered by a black thin adherent UO 2+x oxide layer. On the other hand, by oxidation in the middle temperature region, the sample broke to several pieces of thin plates and blocks, and fine powder at 643-723 K and entirely to fine powder at 775-878 K, all of which were analyzed to be a mixture of U 3 O 8 and ZrO 2 . By oxidation in the high temperature region (1008-1063 K) the sample broke to very fine powder, which consisted of U 3 O 8 and ZrO 2 . Based on the sample shape, the oxide phase identified after oxidation and the slope value of the bilogarithmic plots of the weight gain against time, the oxidation kinetics was analyzed with a paralinear equation in the low temperature region below 503 K and a linear equation in the middle and high temperature regions above 643 K. Oxidation rates of U 0.80 Zr 0.20 (two-phase mixture) in the low and middle temperature regions were smaller than those of uranium metal. A discontinuity in the plot of the linear oxidation rate constant versus reciprocal temperature was found to be present between 723 and 838 K, similarly to the case of uranium metal previously reported. The linear rate constants of single-phase solid solution in the high temperature region above 1008 K seemed to be a little smaller than those estimated by the extrapolation of the values in the middle temperature region. (orig.)

  1. Oxidation of U-20 at% Zr alloy in air at 423 1063 K

    Science.gov (United States)

    Matsui, Tsuneo; Yamada, Takanobu; Ikai, Yasushi; Naito, Keiji

    1993-01-01

    The oxidation behavior of U 0.80Zr 0.20 alloy (two-phase mixture of U and UZr 2 below 878 K and single solid solution above 1008 K) was studied by thermogravimetry in the temperature range from 423 to 1063 K in air. During oxidation in the low temperature region (423-503 K), the sample kept its initial shape (a rectangular rod) and the surface of the sample was covered by a black thin adherent UO2 + x oxide layer. On the other hand, by oxidation in the middle temperature region, the sample broke to several pieces of thin plates and blocks, and fine powder at 643-723 K and entirely to fine powder at 775-878 K, all of which were analyzed to be a mixture of U 3O 8 and ZrO 2. By oxidation in the high temperature region (1008-1063 K) the sample broke to very fine powder, which consisted of U 3O 8 and ZrO 2. Based on the sample shape, the oxide phase identified after oxidation and the slope value of the bilogarithmic plots of the weight gain against time, the oxidation kinetics was analyzed with a paralinear equation in the low temperature region below 503 K and a linear equation in the middle and high temperature regions above 643 K. Oxidation rates of U 0.80Zr 0.20 (two-phase mixture) in the low and middle temperature regions were smaller than those of uranium metal. A discontinuity in the plot of the linear oxidation rate constant versus reciprocal temperature was found to be present between 723 and 838 K, similarly to the case of uranium metal previously reported. The linear rate constants of single-phase solid solution in the high temperature region above 1008 K seemed to be a little smaller than those estimated by the extrapolation of the values in the middle temperature region.

  2. Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.

    2007-07-01

    The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

  3. Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant

    Directory of Open Access Journals (Sweden)

    Wang Y

    2015-07-01

    Full Text Available Yimin Wang,1 Kunping Liu,1,2 Zewei Luo,1 Yixiang Duan1 1Research Center of Analytical Instrumentation, Key Laboratory of Bio-resource and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, 2Faculty of Biotechnology Industry, Chengdu University, Chengdu, People’s Republic of China Background: Currently, surfactant-functionalized nanomaterials are tending toward development of novel tumor-targeted drug carriers to overcome multidrug resistance in cancer therapy. Now, investigating the biocompatibility and uptake mechanism of specific drug delivery systems is a growing trend, but usually a troublesome issue, in simple pharmaceutical research.Methods: We first reported the partially reduced graphene oxide modified with poly(sodium 4-styrenesulfonate (PSS as a nanocarrier system. Then, the nanocarrier was characterized by atomic force microscope, scanning electron microscope, high-resolution transmission electron microscope, ultraviolet–visible (UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-Ray powder diffraction, and Raman spectroscopy. Epirubicin (EPI was attached to PSSG via π–π stacking, hydrogen bonding, and physical absorption to form conjugates of PSSG–EPI. The adsorption and desorption profiles, cytotoxicity coupled with drug accumulation, and uptake of PSSG and PSSG–EPI were evaluated. Finally, the subcellular behaviors, distribution, and biological fate of the drug delivery system were explored by confocal laser scanning microscope using direct fluorescence colocalization imaging and transmission electron microscopy.Results: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility. Moreover, due to much less carboxyl groups retained on the edge of PSSG sheets, the nanocarriers exhibit biocompatibility in vitro. The obtained PSSG shows a high drug-loading capacity of 2.22 mg/mg. The complexes of PSSG–EPI can be transferred to

  4. Initial oxidation processes of Si(001) surfaces by supersonic O2 molecular beams. Different oxidation mechanisms for clean and partially-oxidized surfaces

    International Nuclear Information System (INIS)

    Teraoka, Yuden; Yoshigoe, Akitaka

    2002-01-01

    Potential energy barriers for dissociative chemisorption of O 2 molecules on Si(001) clean surfaces were investigated using supersonic O 2 molecular beams and photoemission spectroscopy. Relative initial sticking probabilities of O 2 molecules and the saturated oxygen amount on the Si(001) surface were measured as a function of incident energy of O 2 molecules. Although the probability was independent on the incident energy in the region larger than 1 eV, the saturated oxygen amount was dependent on the incident energy without energy thresholds. An Si-2p photoemission spectrum of the Si(001) surface oxidized by thermal O 2 gas revealed the oxygen insertion into dimer backbond sites. These facts indicate that a reaction path of the oxygen insertion into dimer backbonds through bridge sites is open for the clean surface oxidation, and the direct chemisorption probability at the backbonds is negligibly small comparing with that at the bridge sites. (author)

  5. Tracking Oxidation During Transport of Trace Gases in Air from the Northern to Southern Hemisphere

    Science.gov (United States)

    Montzka, S. A.; Moore, F. L.; Atlas, E. L.; Parrish, D. D.; Miller, B. R.; Sweeney, C.; McKain, K.; Hall, B. D.; Siso, C.; Crotwell, M.; Hintsa, E. J.; Elkins, J. W.; Blake, D. R.; Barletta, B.; Meinardi, S.; Claxton, T.; Hossaini, R.

    2017-12-01

    Trace gas mole fractions contain the imprint of recent influences on an air mass such as sources, transport, and oxidation. Covariations among the many gases measured from flasks during ATom and HIPPO, and from the ongoing NOAA cooperative air sampling program enable recent influences to be identified from a wide range of sources including industrial activity, biomass burning, emissions from wetlands, and uptake by terrestrial ecosystems. In this work we explore the evolution of trace gas concentrations owing to atmospheric oxidation as air masses pass through the tropics, the atmospheric region with the highest concentrations of the hydroxyl radical. Variations in C2-C5 hydrocarbon concentrations downwind of source regions provide a measure of photochemical ageing in an air mass since emission, but they become less useful when tracking photochemical ageing as air is transported from the NH into the SH owing to their low mixing ratios, lifetimes that are very short relative to transport times, non-industrial sources in the tropics (e.g., biomass burning), and southern hemispheric sources. Instead, we consider a range of trace gases and trace gas pairs that provide a measure of photochemical processing as air transits the tropics. To be useful in this analysis, these trace gases would have lifetimes comparable to interhemispheric transport times, emissions arising from only the NH at constant relative magnitudes, and concentrations sufficient to allow precise and accurate measurements in both hemispheres. Some anthropogenically-emitted chlorinated hydrocarbons meet these requirements and have been measured during ATom, HIPPO, and from NOAA's ongoing surface sampling efforts. Consideration of these results and their implications for tracking photochemical processing in air as it is transported across the tropics will be presented.

  6. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  7. Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Transport from the membrane to the packed bed

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  8. Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Intraparticle mass transport

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

  9. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Intraparticle Mass Transport

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

  10. Methane partial oxidation over a LaCr0.85Ru0.15O3 catalyst : Characterization, activity tests and kinetic modeling

    NARCIS (Netherlands)

    Melchiori, T.; Di Felice, L.; Mota, N.; Navarro, R.M.; Fierro, J.L.G.; Sint Annaland, van M.; Gallucci, F.

    2014-01-01

    A new LaCr0.85Ru0.15O3 perovskite-type catalyst for CH4 partial oxidation with a high activity and selectivity for syngas with good thermal stability and resistance against coking has been developed. In this paper, the catalyst preparation method, catalyst characterization, results of catalytic

  11. The reaction mechanism of the partial oxidation of methane to synthesis gas: a transient kinetic study over rhodium and a comparison with platinum

    NARCIS (Netherlands)

    Mallens, E.P.J.; Hoebink, J.H.B.J.; Marin, G.B.M.M.

    1997-01-01

    The partial oxidation of methane to synthesis gas over rhodium sponge has been investigated by admitting pulses of pure methane and pure oxygen as well as mixtures of methane and oxygen to rhodium sponge at temperatures from 873 to 1023 K. Moreover, pulses of oxygen followed by methane and vice

  12. Heat release from B4C oxidation in steam and air

    International Nuclear Information System (INIS)

    Belovsky, L.

    1996-01-01

    BWR and some PWR cores contain boron carbide (B 4 C) as neutron absorber. During a severe accident, the B 4 C can potentially react with steam under release of heat and hydrogen. Although models for B 4 C oxidation already exist in MELCOR and SCDAP/RELAP5, a development of a new model for another computer code seems to be difficult due to a missing comprehensive description of the current modelling methodology and scarce experimental data. The aim of this paper is to highlight the key points of the B 4 C oxidation using the existing available experimental data and to perform a simple heat balance analysis of the B 4 C/steam and B 4 C/air chemical reactions. The analysis of literature data shows that the B 4 C oxidation phenomenon is qualitatively well described below 1000 deg. C. However, no reliable data exist for the reaction kinetics especially above this temperature. It was found that the experimental results strongly depend on the experimental arrangement. The reaction heats, calculated in this study, indicate that the B 4 C oxidation is an exothermic reaction, releasing more heat in air than in steam. The formation of boric acids from the boron oxide increases the heat release from B 4 C by ∼ 10%, in the worst case. Although the total heat, released in a PWR core from the B 4 C oxidation, is probably much smaller than the heat released from the Zr/steam reaction, it is not excluded that the B 4 C oxidation can locally contribute to the damage of the control elements due to local overheating. Modelling of these phenomena is, however, very difficult due to the complex geometry of the liquefied control elements and due to absence of suitable data on the reaction kinetics. (author). 25 refs, 2 figs, 3 tabs

  13. Zircaloy-4 and M5 high temperature oxidation and nitriding in air

    Energy Technology Data Exchange (ETDEWEB)

    Duriez, C. [Institut de Radioprotection et Surete Nucleaire, Direction de Prevention des Accidents Majeurs, Centre de Cadarache, 13115 St Paul Lez Durance (France)], E-mail: christian.duriez@irsn.fr; Dupont, T.; Schmet, B.; Enoch, F. [Universite Technologique de Troyes, BP 2060, 10010 Troyes (France)

    2008-10-15

    For the purpose of nuclear power plant severe accident analysis, degradation of Zircaloy-4 and M5 cladding tubes in air at high temperature was investigated by thermo-gravimetric analysis, in isothermal conditions, in a 600-1200 deg. C temperature range. Alloys were investigated either in a 'as received' bare state, or after steam pre-oxidation at 500 {sup o}C to simulate in-reactor corrosion. At the beginning of air exposure, the oxidation rate obeys a parabolic law, characteristic of solid-state diffusion limited regime. Parabolic rate constants compare, for Zircaloy-4 as well as for M5, with recently assessed correlations for high temperature Zircaloy-4 steam-oxidation. A thick layer of dense protective zirconia having a columnar structure forms during this diffusion-limited regime. Then, a kinetic transition (breakaway type) occurs, due to radial cracking along the columnar grain boundaries of this protective dense oxide scale. The breakaway is observed for a scale thickness that strongly increases with temperature. At the lowest temperatures, the M5 alloy appears to be breakaway-resistant, showing a delayed transition compared to Zircaloy-4. However, for both alloys, a pre-existing corrosion scale favours the transition, which occurs much earlier. The post transition kinetic regime is linear only for the lowest temperatures investigated. From 800 deg. C, a continuously accelerated regime is observed and is associated with formation of a strongly porous non-protective oxide. A mechanism of nitrogen-assisted oxide growth, involving formation and re-oxidation of ZrN particles, as well as nitrogen associated zirconia phase transformations, is proposed to be responsible for this accelerated degradation.

  14. Oxidation of graphites for core support post in air at high temperatures

    International Nuclear Information System (INIS)

    Imai, Hisashi; Fujii, Kimio; Kurosawa, Takeshi

    1982-07-01

    Oxidation reactions of candidate graphites for core support post with atmospheric air were studied in a temperature range between 550 0 C and 1000 0 C. The reaction rates, temperature dependence of the rates and distribution of bulk density in the oxidized graphites were measured and the characters obtained were compared between the brand of graphites. On the basis of the experimental results, dimension and strength of the post after corrosion with air, which might be introduced in rupture accident of primary coolant tube, were discussed. In the case of IG-11 graphite, it was proved that the strength of post is still sufficient even 100 hours after the beginning of the accident and that, however, it is necessary to insert more deeply the post against graphite blocks. (author)

  15. Air oxidation of aqueous sodium sulfide solutions with coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, D; Chaudhuri, S K [Southern Illinois University, Carbondale, IL (United States). Dept. of Mining Engineering

    1999-02-01

    The paper investigated the potential of coal fly ash as a catalyst in the air oxidation of aqueous sodium sulfide (Na{sub 2}S) solutions in the temperature range of 303-333 K. The rate of oxidation was found to be independent of the initial concentration of Na{sub 2}S in the range of 5.80 x 10{sup -2} - 28.45 x 10{sup -2} kmol/m{sup 3}. The effects of fly ash loading, source of fly ash, speed of agitation, air flow rate, fly ash particle size were also studied. Experimental results suggested a film-diffusion controlled reaction mechanism. The deactivation of the catalytic effect of fly ash was found to be less than 31% even after five repeated uses.

  16. [Kinetics of catalytic wet air oxidation of phenol in trickle bed reactor].

    Science.gov (United States)

    Li, Guang-ming; Zhao, Jian-fu; Wang, Hua; Zhao, Xiu-hua; Zhou, Yang-yuan

    2004-05-01

    By using a trickle bed reactor which was designed by the authors, the catalytic wet air oxidation reaction of phenol on CuO/gamma-Al2O3 catalyst was studied. The results showed that in mild operation conditions (at temperature of 180 degrees C, pressure of 3 MPa, liquid feed rate of 1.668 L x h(-1) and oxygen feed rate of 160 L x h(-1)), the removal of phenol can be over 90%. The curve of phenol conversion is similar to "S" like autocatalytic reaction, and is accordance with chain reaction of free radical. The kinetic model of pseudo homogenous reactor fits the catalytic wet air oxidation reaction of phenol. The effects of initial concentration of phenol, liquid feed rate and temperature for reaction also were investigated.

  17. Contamination of hospital compressed air with nitric oxide: unwitting replacement therapy.

    Science.gov (United States)

    Pinsky, M R; Genc, F; Lee, K H; Delgado, E

    1997-06-01

    Inhaled nitric oxide (NO) at levels between 5 and 80 ppm has been used experimentally to treat a variety of conditions. NO also is a common environmental air pollutant in industrial regions. As compressed hospital air is drawn from the local environment, we speculated that it may contain NO contamination, which, if present, would provide unwitting inhaled NO therapy to all subjects respiring this compressed gas. NO levels were measured twice daily from ambient hospital air and compressed gas sources driving positive pressure ventilation from two adjacent hospitals and compared with NO levels reported daily by local Environmental Protection Agency sources. An NO chemiluminescence analyzer (Sievers 270B; Boulder, Colo) sensitive to > or =2 parts per billion was used to measure NO levels in ambient air and compressed gas. NO levels in ambient air and hospital compressed air covaried from day to day, and absolute levels of NO differed between hospitals with the difference never exceeding 1.4 ppm (range, 0 to 1.4 ppm; median, 0.07 ppm). The hospital with the highest usage level of compressed air had the highest levels of NO, which approximated ambient levels of NO. NO levels were lowest on weekends in both hospitals. We also documented inadvertent NO contamination in one hospital occurring over 5 days, which corresponded to welding activity near the intake port for fresh gas. This contamination resulted in system-wide NO levels of 5 to 8 ppm. Hospital compressed air contains highly variable levels of NO that tend to covary with ambient NO levels and to be highest when the rate of usage is high enough to preclude natural degradation of NO in 21% oxygen. Assuming that inhaled NO may alter gas exchange, pulmonary hemodynamics, and outcome from acute lung injury, the role of unwitting variable NO of hospital compressed air needs to be evaluated.

  18. Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

    Science.gov (United States)

    Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.; Campuzano-Jost, Pedro; Hu, Weiwei; Seco, Roger; Sjostedt, Steven J.; Park, Jeong-Hoo; Guenther, Alex B.; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Thalman, Ryan; Wang, Jian; Yee, Lindsay D.; Wernis, Rebecca; Isaacman-VanWertz, Gabriel; Goldstein, Allen H.; Liu, Yingjun; Springston, Stephen R.; Souza, Rodrigo; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Jimenez, Jose L.

    2018-01-01

    Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O3, over ranges from hours to days (O3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to as much as 10 µg m-3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ˜ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O3, they could only explain 10-50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign

  19. Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

    Directory of Open Access Journals (Sweden)

    B. B. Palm

    2018-01-01

    Full Text Available Secondary organic aerosol (SOA formation from ambient air was studied using an oxidation flow reactor (OFR coupled to an aerosol mass spectrometer (AMS during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5 field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O3, over ranges from hours to days (O3 or weeks (OH of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to as much as 10 µg m−3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ∼ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds are present in ambient air and can explain such additional SOA formation. To investigate the sources of the

  20. On the degradability of printing and dyeing wastewater by wet air oxidation.

    Science.gov (United States)

    Hu, X; Lei, L; Chen, G; Yue, P L

    2001-06-01

    A modified first-order kinetics model was used to study the wet air oxidation of printing and dyeing wastewater. The model simulations are in good agreement with experimental data. The results indicate that a certain fraction of organic pollutants in the printing and dyeing wastewater could not be removed even at elevated temperature and prolonged reaction time. The ratio of degradable organic matter is found independent of temperature and can be improved by using a catalyst.

  1. Laser assisted green synthesis of free standing reduced graphene oxides at the water–air interface

    International Nuclear Information System (INIS)

    Compagnini, G; Russo, P; Tomarchio, F; Puglisi, O; D’Urso, L; Scalese, S

    2012-01-01

    A single step, scalable and green strategy has been developed to obtain reduced graphene oxide layers in water dispersion through nanosecond laser pulse irradiation of carbon targets. The layers spontaneously migrate at the water–air interface, forming sheets of several tens of micrometers and show intense ultraviolet photoluminescence. This unique condition offers an intriguing environment where opposing dielectric media meet and can be used in all those processes where molecular interactions such as hydrogen bonding and electrostatic interactions are greatly enhanced. (paper)

  2. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

    Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.

  3. Using advanced oxidation treatment for biofilm inactivation by varying water vapor content in air plasma

    Science.gov (United States)

    Ryota, Suganuma; Koichi, Yasuoka

    2015-09-01

    Biofilms are caused by environmental degradation in food factories and medical facilities. The inactivation of biofilms involves making them react with chemicals including chlorine, hydrogen peroxide, and ozone, although inactivation using chemicals has a potential problem because of the hazardous properties of the residual substance and hydrogen peroxide, which have slow reaction velocity. We successfully performed an advanced oxidation process (AOP) using air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were generated by varying the amount of water vapor supplied to the plasma. By varying the content of the water included in the air, the main product was changed from air plasma. When we increased the water content in the air, hydrogen peroxide was produced, while ozone peroxide was produced when we decreased the water content in the air. By varying the amount of water vapor, we realized a 99.9% reduction in the amount of bacteria in the biofilm when we discharged humidified air only. This work was supported by JSPS KAKENHI Grant Number 25630104.

  4. Formation of polymerization compounds during thermal oxidation of cottonseed oil, partially hydrogenated cottonseed oil and their blends

    Directory of Open Access Journals (Sweden)

    Barrera-Arellano, D. Laboratório de Óleos e Gorduras, Departa

    2006-09-01

    Full Text Available Samples of cottonseed oil, partially hydrogenated cottonseed oil and their blends, with iodine values between 60 and 110, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180 °C, for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation compounds and of tocopherols. The influence of the degree of hydrogenation on the formation of dimers and polymers and the role of originally present tocopherols in the protection of fats and oils against thermal degradation was verified. The degradation curves for tocopherols showed a fast destruction rate for the tocopherols present in cottonseed fats and oil (α and γ-tocopherols, with residual levels close to zero after 10 hours under thermal oxidation conditions. Nevertheless, samples with their natural tocopherols presented a slower rate of thermal degradation. The unsaturation degree was apparently more important in the protection against thermal degradation than the content of tocopherolsMuestras de aceite de algodón, aceite de algodón parcialmente hidrogenado y sus mezclas, con índices de yodo de 60 a 110, tratadas o no con óxido de aluminio, fueron sometidas a termoxidación, a 180 °C, durante 10 horas. Se retiraron muestras en los tiempos 0, 2, 5, 8 y 10 horas, para determinación de dímeros y polímeros (compuestos de degradación y de tocoferoles. Se verificó la influencia del grado de hidrogenación sobre la formación de dímeros y polímeros, y también el papel de los tocoferoles originalmente presentes en el aceite y en las grasas, en la protección contra la degradación térmica. Las curvas de degradación de los tocoferoles mostraron una destrucción bastante rápida de los tocoferoles presentes en el aceite y en las grasas de algodón (α y γ-tocoferoles, con niveles residuales próximos a cero después de 10 horas de termoxidación. Aún así, muestras con sus

  5. Evaluation of Ultra-Violet Photocatalytic Oxidation for Indoor AirApplications

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, A.T.; Sullivan, D.P.; Fisk, W.J.

    2006-02-01

    Acceptable indoor air quality in office buildings may be achieved with less energy by combining effective air cleaning systems for volatile organic compounds (VOCs) with particle filtration then by relying solely on ventilation. For such applications, ultraviolet photocatalytic oxidation (UVPCO) systems are being developed for VOC destruction. An experimental evaluation of a UVPCO system is reported. The evaluation was unique in that it employed complex mixtures of VOCs commonly found in office buildings at realistically low concentrations. VOC conversion efficiencies varied over a broad range, usually exceeded 20%, and were as high as {approx}80%. Conversion efficiency generally diminished with increased air flow rate. Significant amounts of formaldehyde and acetaldehyde were produced due to incomplete mineralization. The results indicate that formaldehyde and acetaldehyde production rates may need to be reduced before such UVPCO systems can be deployed safely in occupied buildings.

  6. Impact of clay mineral on air oxidation of PAH-contaminated soils.

    Science.gov (United States)

    Biache, Coralie; Kouadio, Olivier; Lorgeoux, Catherine; Faure, Pierre

    2014-09-01

    This work investigated the impact of a clay mineral (bentonite) on the air oxidation of the solvent extractable organic matters (EOMs) and the PAHs from contaminated soils. EOMs were isolated from two coking plant soils and mixed with silica sand or bentonite. These samples, as well as raw soils and bentonite/soil mixtures, were oxidized in air at 60 and 100 °C for 160 days. Mineralization was followed by measuring the CO2 produced over the experiments. EOM, polycyclic aromatic compound (PAC), including PAH, contents were also determined. Oxidation led to a decrease in EOM contents and PAH concentrations, these diminutions were enhanced by the presence of bentonite. Transfer of carbon from EOM to insoluble organic matter pointed out a condensation phenomenon leading to a stabilization of the contamination. Higher mineralization rates, observed during the oxidation of the soil/bentonite mixtures, seem to indicate that this clay mineral had a positive influence on the transformation of PAC into CO2.

  7. Copper(I)/TEMPO Catalyzed Aerobic Oxidation of Primary Alcohols to Aldehydes with Ambient Air

    Science.gov (United States)

    Hoover, Jessica M.; Steves, Janelle E.; Stahl, Shannon S.

    2012-01-01

    This protocol describes a practical laboratory-scale method for aerobic oxidation of primary alcohols to aldehydes, using a chemoselective CuI/TEMPO catalyst system. The catalyst is prepared in situ from commercially available reagents, and the reactions are performed in a common organic solvent (acetonitrile) with ambient air as the oxidant. Three different reaction conditions and three procedures for the isolation and purification of the aldehyde product are presented. The oxidations of eight different alcohols, described here, include representative examples of each reaction condition and purification method. Reaction times vary from 20 min to 24 h, depending on the alcohol, while the purification methods each take about 2 h. The total time necessary for the complete protocol ranges from 3 – 26 h. PMID:22635108

  8. Oxidative damage to DNA and lipids as biomarkers of exposure to air pollution

    DEFF Research Database (Denmark)

    Møller, Peter; Loft, Steffen

    2010-01-01

    BACKGROUND: Air pollution is thought to exert health effects through oxidative stress, which causes damage to DNA and lipids. OBJECTIVE: We determined whether levels of oxidatively damaged DNA and lipid peroxidation products in cells or bodily fluids from humans are useful biomarkers...... of biologically effective dose in studies of the health effects of exposure to particulate matter (PM) from combustion processes. DATA SOURCES: We identified publications that reported estimated associations between environmental exposure to PM and oxidative damage to DNA and lipids in PubMed and EMBASE. We also...... identified publications from reference lists and articles cited in the Web of Science. DATA EXTRACTION: For each study, we obtained information on the estimated effect size to calculate the standardized mean difference (unitless) and determined the potential for errors in exposure assessment and analysis...

  9. Oxidative degradation of toluene and limonene in air by pulsed corona technology

    International Nuclear Information System (INIS)

    Hoeben, W F L M; Beckers, F J C M; Pemen, A J M; Van Heesch, E J M; Kling, W L

    2012-01-01

    The oxidative degradation of two volatile organic compounds, i.e. toluene (fossil fuel based VOC) and limonene (biogenic VOC), has been studied. A hybrid pulsed power corona reactor with adjustable energy density has been utilized for degradation of ppm level target compounds in large air flows. The observed oxidation product range features an energy density-dependent spectrum of oxygen-functional hydrocarbons, which has been qualitatively discussed on the basis of literature studies. Typically, observed stable oxidation products for both target compounds are the biocompatible carboxylic acids acetic and formic acid. Measured degradation G-values are 23 nmol J -1 at 74% conversion of 70 ppm toluene and 181 nmol J -1 at 81% conversion of 10 ppm limonene. (paper)

  10. Cast Stone Oxidation Front Evaluation: Preliminary Results For Samples Exposed To Moist Air

    International Nuclear Information System (INIS)

    Langton, C. A.; Almond, P. M.

    2013-01-01

    The rate of oxidation is important to the long-term performance of reducing salt waste forms because the solubility of some contaminants, e.g., technetium, is a function of oxidation state. TcO 4 - in the salt solution is reduced to Tc(IV) and has been shown to react with ingredients in the waste form to precipitate low solubility sulfide and/or oxide phases. Upon exposure to oxygen, the compounds containing Tc(IV) oxidize to the pertechnetate ion, Tc(VII)O 4 - , which is very soluble. Consequently the rate of technetium oxidation front advancement into a monolith and the technetium leaching profile as a function of depth from an exposed surface are important to waste form performance and ground water concentration predictions. An approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) based on leaching of select contaminants of concern is described in this report. In addition, the relationship between reduction capacity and contaminant oxidation is addressed. Chromate (Cr(VI) was used as a non-radioactive surrogate for pertechnetate, Tc(VII), in Cast Stone samples prepared with 5 M Simulant. Cast Stone spiked with pertechnetate was also prepared and tested. Depth discrete subsamples spiked with Cr were cut from Cast Stone exposed to Savannah River Site (SRS) outdoor ambient temperature fluctuations and moist air. Depth discrete subsamples spiked with Tc-99 were cut from Cast Stone exposed to laboratory ambient temperature fluctuations and moist air. Similar conditions are expected to be encountered in the Cast Stone curing container. The leachability of Cr and Tc-99 and the reduction capacities, measured by the Angus-Glasser method, were determined for each subsample as a function of depth from the exposed surface. The results obtained to date were focused on continued method development and are preliminary and apply to the sample composition and curing / exposure conditions described in this report. The Cr oxidation front

  11. Air-electron stream interactions during magnetic resonance IGRT. Skin irradiation outside the treatment field during accelerated partial breast irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Min [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Advanced Institutes of Convergence Technology, Robotics Research Laboratory for Extreme Environments, Suwon (Korea, Republic of); Shin, Kyung Hwan; Wu, Hong-Gyun [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiation Oncology, Seoul (Korea, Republic of); Kim, Jung-in; Park, So-Yeon; Kim, Jin Ho [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Seoul National University Hospital, Biomedical Research Institute, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Jeon, Seung Hyuck [Seoul National University Hospital, Department of Radiation Oncology, Seoul (Korea, Republic of); Choi, Noorie [Seoul National University College of Medicine, Department of Radiation Oncology, Seoul (Korea, Republic of)

    2018-01-15

    To investigate and to prevent irradiation outside the treatment field caused by an electron stream in the air generated by the magnetic field during magnetic resonance image-guided accelerated partial breast irradiation (APBI). In all, 20 patients who received APBI with a magnetic resonance image-guided radiation therapy (MR-IGRT) system were prospectively studied. The prescription dose was 38.5 Gy in 10 fractions of 3.85 Gy and delivered with a tri-cobalt system (the ViewRay system). For each patient, primary plans were delivered for the first five fractions and modified plans with different gantry angles from those of the primary plan (in-treatment plans) were delivered for the remaining five fractions to reduce the skin dose. A 1 cm thick bolus was placed in front of the patient's jaw, ipsilateral shoulder, and arm to shield them from the electron stream. Radiochromic EBT3 films were attached to the front (towards the breast) and back (towards the head) of the bolus during treatment. Correlations between the measured values and the tumor locations, treatment times, and tumor sizes were investigated. For a single fraction delivery, the average areas of the measured isodoses of 14% (0.54 Gy), 12% (0.46 Gy), and 10% (0.39 Gy) at the front of the boluses were as large as 3, 10.4, and 21.4 cm{sup 2}, respectively, whereas no significant dose could be measured at the back of the boluses. Statistically significant but weak correlations were observed between the measured values and the treatment times. During radiotherapy for breast cancer with an MR-IGRT system, the patient must be shielded from electron streams in the air generated by the interaction of the magnetic field with the beams of the three-cobalt treatment unit to avoid unwanted irradiation of the skin outside the treatment field. (orig.) [German] Beim Einsatz eines Magnetresonanztomographie(MRT)-gefuehrten Bestrahlungsgeraets kann durch die Wechselwirkung von Magnetfeld und Strahlenquelle unerwuenscht

  12. Raman spectroscopy analysis of air grown oxide scale developed on pure zirconium substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kurpaska, L., E-mail: lukasz.kurpaska@ncbj.gov.pl [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France); National Center for Nuclear Research, St. A. Soltana 7/23, 05-400 Otwock-Swierk (Poland); Favergeon, J. [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France); Lahoche, L. [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France); Laboratoire des Technologies Innovantes, Université de Picardie Jules-Verne, EA 3899, Avenue des Facultés – Le Bailly, 80025 Amiens Cedex (France); El-Marssi, M. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules-Verne, 33 rue St. Leu, 80039 Amiens Cedex (France); Grosseau Poussard, J.-L. [LaSIE UMR-CNRS 7356, Pole Sciences et Technologie, Universite de La Rochelle, av. M Crepeau, 17042 La Rochelle, Cedex (France); Moulin, G.; Roelandt, J.-M. [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France)

    2015-11-15

    Using Raman spectroscopy technique, external and internal parts of zirconia oxide films developed at 500 °C and 600 °C on pure zirconium substrate under air at normal atmospheric pressure have been examined. Comparison of Raman peak positions of tetragonal and monoclinic zirconia phases, recorded during the oxide growth at elevated temperature, and after cooling at room temperature have been presented. Subsequently, Raman peak positions (or shifts) were interpreted in relation with the stress evolution in the growing zirconia scale, especially closed to the metal/oxide interface, where the influence of compressive stress in the oxide is the biggest. Reported results, for the first time show the presence of a continuous layer of tetragonal zirconia phase developed in the proximity of pure zirconium substrate. Based on the Raman peak positions we prove that this tetragonal layer is stabilized by the high compressive stress and sub-stoichiometry level. Presence of the tetragonal phase located in the outer part of the scale have been confirmed, yet its Raman characteristics suggest a stress-free tetragonal phase, therefore different type of stabilization mechanism. Presented study suggest that its stabilization could be related to the lattice defects introduced by highstoichiometry of zirconia or presence of heterovalent cations. - Highlights: • The oxide layer consists of a mixture of tetragonal and monoclinic phases, clearly distinguishable by Raman spectroscopy. • The layer located close to the metal/oxide interphase consists mainly of the tetragonal phase. • Small amount of tetragonal layer located in the external oxide scale have been observed. • Stabilization mechanism of the tetragonal phase located in the external part of the oxide have been proposed.

  13. Short-Term Exposure to Air Pollution and Biomarkers of Oxidative Stress: The Framingham Heart Study.

    Science.gov (United States)

    Li, Wenyuan; Wilker, Elissa H; Dorans, Kirsten S; Rice, Mary B; Schwartz, Joel; Coull, Brent A; Koutrakis, Petros; Gold, Diane R; Keaney, John F; Lin, Honghuang; Vasan, Ramachandran S; Benjamin, Emelia J; Mittleman, Murray A

    2016-04-28

    Short-term exposure to elevated air pollution has been associated with higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution hypothesized as an important underlying mechanism. However, few community-based studies have assessed this association. Two thousand thirty-five Framingham Offspring Cohort participants living within 50 km of the Harvard Boston Supersite who were not current smokers were included. We assessed circulating biomarkers of oxidative stress including blood myeloperoxidase at the seventh examination (1998-2001) and urinary creatinine-indexed 8-epi-prostaglandin F2α (8-epi-PGF2α) at the seventh and eighth (2005-2008) examinations. We measured fine particulate matter (PM2.5), black carbon, sulfate, nitrogen oxides, and ozone at the Supersite and calculated 1-, 2-, 3-, 5-, and 7-day moving averages of each pollutant. Measured myeloperoxidase and 8-epi-PGF2α were loge transformed. We used linear regression models and linear mixed-effects models with random intercepts for myeloperoxidase and indexed 8-epi-PGF2α, respectively. Models were adjusted for demographic variables, individual- and area-level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of PM2.5 and black carbon with myeloperoxidase across multiple moving averages. Additionally, 2- to 7-day moving averages of PM2.5 and sulfate were consistently positively associated with 8-epi-PGF2α. Stronger positive associations of black carbon and sulfate with myeloperoxidase were observed among participants with diabetes than in those without. Our community-based investigation supports an association of select markers of ambient air pollution with circulating biomarkers of oxidative stress. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  14. Effect of PEEP and inhaled nitric oxide on pulmonary gas exchange during gaseous and partial liquid ventilation with small volumes of perfluorocarbon.

    Science.gov (United States)

    Max, M; Kuhlen, R; Falter, F; Reyle-Hahn, M; Dembinski, R; Rossaint, R

    2000-04-01

    Partial liquid ventilation, positive end-expiratory pressure (PEEP) and inhaled nitric oxide (NO) can improve ventilation/perfusion mismatch in acute lung injury (ALI). The aim of the present study was to compare gas exchange and hemodynamics in experimental ALI during gaseous and partial liquid ventilation at two different levels of PEEP, with and without the inhalation of nitric oxide. Seven pigs (24+/-2 kg BW) were surfactant-depleted by repeated lung lavage with saline. Gas exchange and hemodynamic parameters were assessed in all animals during gaseous and subsequent partial liquid ventilation at two levels of PEEP (5 and 15 cmH2O) and intermittent inhalation of 10 ppm NO. Arterial oxygenation increased significantly with a simultaneous decrease in cardiac output when PEEP 15 cmH2O was applied during gaseous and partial liquid ventilation. All other hemodynamic parameters revealed no relevant changes. Inhalation of NO and instillation of perfluorocarbon had no additive effects on pulmonary gas exchange when compared to PEEP 15 cmH2O alone. In experimental lung injury, improvements in gas exchange are most distinct during mechanical ventilation with PEEP 15 cmH2O without significantly impairing hemodynamics. Partial liquid ventilation and inhaled NO did not cause an additive increase of PaO2.

  15. AIRE variations in Addison's disease and autoimmune polyendocrine syndromes (APS): partial gene deletions contribute to APS I.

    Science.gov (United States)

    Bøe Wolff, A S; Oftedal, B; Johansson, S; Bruland, O; Løvås, K; Meager, A; Pedersen, C; Husebye, E S; Knappskog, P M

    2008-03-01

    Autoimmune Addison's disease (AAD) is often associated with other components in autoimmune polyendocrine syndromes (APS). Whereas APS I is caused by mutations in the AIRE gene, the susceptibility genes for AAD and APS II are unclear. In the present study, we investigated whether polymorphisms or copy number variations in the AIRE gene were associated with AAD and APS II. First, nine SNPs in the AIRE gene were analyzed in 311 patients with AAD and APS II and 521 healthy controls, identifying no associated risk. Second, in a subgroup of 25 of these patients, AIRE sequencing revealed three novel polymorphisms. Finally, the AIRE copy number was determined by duplex quantitative PCR in 14 patients with APS I, 161 patients with AAD and APS II and in 39 healthy subjects. In two Scandinavian APS I patients previously reported to be homozygous for common AIRE mutations, we identified large deletions of the AIRE gene covering at least exon 2 to exon 8. We conclude that polymorphisms in the AIRE gene are not associated with AAD and APS II. We further suggest that DNA analysis of the parents of patients found to be homozygous for mutations in AIRE, always should be performed.

  16. Oxidation of iridium coating on rhenium coated graphite at elevated temperature in stagnated air

    International Nuclear Information System (INIS)

    Huang, Yongle; Bai, Shuxin; Zhang, Hong; Ye, Yicong

    2015-01-01

    Highlights: • Continuous and dense Ir coatings were prepared on graphite by electrodepostion. • The purification of the as-prepared Ir coating was higher than about 99.98%. • The Ir/Re/C specimen kept integrity without significant failures after oxidation. • The average oxidation rate of the Ir coating was about 0.219 mg/(cm 2 min). • Penetrating holes at gains boundaries resulted in the failure of the Ir coating. - Abstract: Continuous and dense iridium coatings were prepared on the rhenium coated graphite specimens by electrodeposition. The iridium/rhenium coated graphite (Ir/Re/C) specimens were oxidized at elevated temperatures in stagnated air for 3600 s. The purification of the as-prepared Ir coating was higher than about 99.98% with the main impurity elements Si, Al, Fe and Ru. After oxidation, the Ir/Re/C specimens kept integrity without significant failures and the average oxidation rate was about 0.219 mg/(cm 2 min). Pores were found at the grain boundaries and concentrated to penetrating holes with the growth of Ir grains, which resulted in disastrous failures of the Ir coating

  17. Oxidation of iridium coating on rhenium coated graphite at elevated temperature in stagnated air

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yongle; Bai, Shuxin, E-mail: NUDT_MSE_501@163.com; Zhang, Hong; Ye, Yicong

    2015-02-15

    Highlights: • Continuous and dense Ir coatings were prepared on graphite by electrodepostion. • The purification of the as-prepared Ir coating was higher than about 99.98%. • The Ir/Re/C specimen kept integrity without significant failures after oxidation. • The average oxidation rate of the Ir coating was about 0.219 mg/(cm{sup 2} min). • Penetrating holes at gains boundaries resulted in the failure of the Ir coating. - Abstract: Continuous and dense iridium coatings were prepared on the rhenium coated graphite specimens by electrodeposition. The iridium/rhenium coated graphite (Ir/Re/C) specimens were oxidized at elevated temperatures in stagnated air for 3600 s. The purification of the as-prepared Ir coating was higher than about 99.98% with the main impurity elements Si, Al, Fe and Ru. After oxidation, the Ir/Re/C specimens kept integrity without significant failures and the average oxidation rate was about 0.219 mg/(cm{sup 2} min). Pores were found at the grain boundaries and concentrated to penetrating holes with the growth of Ir grains, which resulted in disastrous failures of the Ir coating.

  18. The air oxidation behavior of lanthanum ion implanted zirconium at 500 deg. C

    CERN Document Server

    Peng, D Q; Chen, X W; Zhou, Q G

    2003-01-01

    The beneficial effect of lanthanum ion implantation on the oxidation behavior of zirconium at 500 deg. C has been studied. Zirconium specimens were implanted by lanthanum ions using a MEVVA source at energy of 40 keV with a fluence range from 1x10 sup 1 sup 6 to 1x10 sup 1 sup 7 ions/cm sup 2 at maximum temperature of 130 deg. C, The weight gain curves were measured after being oxidized in air at 500 deg. C for 100 min, which showed that a significant improvement was achieved in the oxidation behavior of zirconium ion implanted with lanthanum compared with that of the as-received zirconium. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy; and then the depth distributions of the elements in the surface of the samples were obtained by Auger electron spectroscopy. Glancing angle X-ray diffraction at 0.3 deg. incident angles was employed to examine the modification of its phase transformation because of the lanthanum ion implantation in the oxide films. It was obviously fou...

  19. Investigation of partial oxidation of hydrogen sulfide for dry desulfurisation of fuel gases; Untersuchung der Partialoxidation von Schwefelwasserstoff zur Trockenentschwefelung von Brenngasen

    Energy Technology Data Exchange (ETDEWEB)

    Kliemczak, U.

    2002-07-01

    Three process variants for direct desulfurisation in the dry state of coal gasification gases by partial oxidation of H{sub 2}S were investigated in Prenflo conditions: 1. Heterogeneously catalyzed partial oxidation of H{sub 2}S on fly dust followed by sulfur deposition on the dust; 2. Non-catalyzed partial oxidation of H{sub 2}S in a homogeneous gaseous phase followed by sulfur deposition in a spray separator; 3. Heterogeneously catalyzed partial oxidation of H{sub 2}S in a fixed bed. The experiments were carried out in conditions similar to the crude gas conditions of slag bath gasification at SVZ Schwarze Pumpe. The fixed bed materials investigated were hearth furnace coke, Berl saddles, and an activated carbon developed specially for the investigations, Oxorbon CJ. The focus of the investigations was on the envisaged continuous operation of the process. [German] Im Rahmen der vorliegenden Arbeit wurde an einer zu diesem Zweck modifizierten Technikumsanlage die trockene Direktentschwefelung von Brenngasen aus der Kohlevergasung durch partielle Oxidation von H{sub 2}S untersucht. Im Vordergrund standen zwei Verfahrensvarianten, deren Eignung fuer die Bedingungen der Prenflo-Vergasung ueberprueft werden sollte: Variante 1: die heterogen katalysierte Partialoxidation von H{sub 2}S an Flugstaub mit anschliessender Schwefelabscheidung auf dem Staub und, Variante 2: die nichtkatalysierte Partialoxidation von H{sub 2}S in homogener Gasphase mit anschliessender Schwefelabscheidung in einem Spruehabscheider. Ausgehend von den Versuchsergebnissen der Verfahrensvarianten 1 und 2 wurde zusaetzlich als Verfahrensvariante 3 die heterogen katalysierte Partialoxidation von H{sub 2}S am Festbett untersucht. Diese Versuche orientierten sich an den Rohgasbedingungen der Schlackebadvergasung des SVZ Schwarze Pumpe. Als Festbettmaterialien kamen Herdofenkoks, Berlsaettel und eine, speziell fuer diese Verfahrensvariante entwickelte Aktivkohle Oxorbon CJ, zum Einsatz. Die Eignung des

  20. Bias-induced migration of ionized donors in amorphous oxide semiconductor thin-film transistors with full bottom-gate and partial top-gate structures

    Directory of Open Access Journals (Sweden)

    Mallory Mativenga

    2012-09-01

    Full Text Available Bias-induced charge migration in amorphous oxide semiconductor thin-film transistors (TFTs confirmed by overshoots of mobility after bias stressing dual gated TFTs is presented. The overshoots in mobility are reversible and only occur in TFTs with a full bottom-gate (covers the whole channel and partial top-gate (covers only a portion of the channel, indicating a bias-induced uneven distribution of ionized donors: Ionized donors migrate towards the region of the channel that is located underneath the partial top-gate and the decrease in the density of ionized donors in the uncovered portion results in the reversible increase in mobility.

  1. New, Efficient, and Reliable Air Electrode Material for Proton-Conducting Reversible Solid Oxide Cells.

    Science.gov (United States)

    Huan, Daoming; Shi, Nai; Zhang, Lu; Tan, Wenzhou; Xie, Yun; Wang, Wanhua; Xia, Changrong; Peng, Ranran; Lu, Yalin

    2018-01-17

    Driven by the demand to minimize fluctuation in common renewable energies, reversible solid oxide cells (RSOCs) have drawn increasing attention for they can operate either as fuel cells to produce electricity or as electrolysis cells to store electricity. Unfortunately, development of proton-conducting RSOCs (P-RSOCs) faces a major challenge of poor reliability because of the high content of steam involved in air electrode reactions, which could seriously decay the lifetime of air electrode materials. In this work, a very stable and efficient air electrode, SrEu 2 Fe 1.8 Co 0.2 O 7-δ (SEFC) with layer structure, is designed and deployed in P-RSOCs. X-ray diffraction analysis and High-angle annular dark-filed scanning transmission electron microscopy images of SEFC reveal that Sr atoms occupy the center of perovskite slabs, whereas Eu atoms arrange orderly in the rock-salt layer. Such a special structure of SEFC largely depresses its Lewis basicity and therefore its reactivity with steam. Applying the SEFC air electrode, our button switches smoothly between both fuel cell and electrolysis cell (EC) modes with no obvious degradation over a 135 h long-term test under wet H 2 (∼3% H 2 O) and 10% H 2 O-air atmospheres. A record of over 230 h is achieved in the long-term stability test in the EC mode, doubling the longest test that had been previously reported. Besides good stability, SEFC demonstrates great catalytic activity toward air electrode reactions when compared with traditional La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ air electrodes. This research highlights the potential of stable and efficient P-RSOCs as an important part in a sustainable new energy power system.

  2. Internal reforming characteristics of cermet supported solid oxide fuel cell using yttria stabilized zirconia fed with partially reformed methane

    Energy Technology Data Exchange (ETDEWEB)

    Momma, Akihiko; Takano, Kiyonami; Tanaka, Yohei; Negishi, Akira; Kato, Ken; Nozaki, Ken; Kato, Tohru [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono Tsukuba Ibaraki, 305-8568 (Japan); Ichigi, Takenori; Matsuda, Kazuyuki; Ryu, Takashi [Application Development Project, Corporate R and D, NGK Insulators, Ltd., 2-56 Suda-cho Mizuho-ku Nagoya-shi Aichi, 467-8530 (Japan)

    2009-08-01

    In order to investigate the internal reforming characteristics in a cermet supported solid oxide fuel cell (SOFC) using YSZ as the electrolyte, the concentration profiles of the gaseous species along the gas flow direction in the anode were measured. Partially reformed methane using a pre-reformer kept at a constant temperature is supplied to the center of the cell which is operated with a seal-less structure at the gas outlet. The anode gas is sucked in via silica capillaries to the initially evacuated gas tanks. The process is simultaneously carried out using five sampling ports. The sampled gas is analyzed by a gas chromatograph. Most of the measurements are made at the cell temperature (T{sub cell}) of 750 C and at various temperatures of the pre-reformer (T{sub ref}) with various fuel utilizations (U{sub f}) of the cell. The composition of the fuel at the inlet of the anode was confirmed to be almost the same as that theoretically calculated assuming equilibrium at the temperature of the pre-reformer. The effect of internal reforming in the anode is clearly observed as a steady decrease in the methane concentration along the flow axis. The effect of the water-gas shift reaction is also observed as a decrease in the CO{sub 2} concentration and an increase of CO concentration around the gas inlet region, as the water-gas shift reaction inversely proceeds when T{sub cell} is higher than T{sub ref}. The diffusion of nitrogen from the seal-less outermost edge is observed, and the diffusion is confirmed to be more significant as U{sub f} decreases. The observations are compared with the results obtained by the SOFC supported by lanthanum gallate electrolyte. With respect to the internal reforming performance, the cell investigated here is found to be more effective when compared to the previously reported electrolyte supported cell. (author)

  3. Internal reforming characteristics of cermet supported solid oxide fuel cell using yttria stabilized zirconia fed with partially reformed methane

    Science.gov (United States)

    Momma, Akihiko; Takano, Kiyonami; Tanaka, Yohei; Negishi, Akira; Kato, Ken; Nozaki, Ken; Kato, Tohru; Ichigi, Takenori; Matsuda, Kazuyuki; Ryu, Takashi

    In order to investigate the internal reforming characteristics in a cermet supported solid oxide fuel cell (SOFC) using YSZ as the electrolyte, the concentration profiles of the gaseous species along the gas flow direction in the anode were measured. Partially reformed methane using a pre-reformer kept at a constant temperature is supplied to the center of the cell which is operated with a seal-less structure at the gas outlet. The anode gas is sucked in via silica capillaries to the initially evacuated gas tanks. The process is simultaneously carried out using five sampling ports. The sampled gas is analyzed by a gas chromatograph. Most of the measurements are made at the cell temperature (T cell) of 750 °C and at various temperatures of the pre-reformer (T ref) with various fuel utilizations (U f) of the cell. The composition of the fuel at the inlet of the anode was confirmed to be almost the same as that theoretically calculated assuming equilibrium at the temperature of the pre-reformer. The effect of internal reforming in the anode is clearly observed as a steady decrease in the methane concentration along the flow axis. The effect of the water-gas shift reaction is also observed as a decrease in the CO 2 concentration and an increase of CO concentration around the gas inlet region, as the water-gas shift reaction inversely proceeds when T cell is higher than T ref. The diffusion of nitrogen from the seal-less outermost edge is observed, and the diffusion is confirmed to be more significant as U f decreases. The observations are compared with the results obtained by the SOFC supported by lanthanum gallate electrolyte. With respect to the internal reforming performance, the cell investigated here is found to be more effective when compared to the previously reported electrolyte supported cell.

  4. A polygeneration from a dual-gas partial catalytic oxidation coupling with an oxygen-permeable membrane reactor

    International Nuclear Information System (INIS)

    Hao, Yanhong; Huang, Yi; Gong, Minhui; Li, Wenying; Feng, Jie; Yi, Qun

    2015-01-01

    Highlights: • A new polygeneration system (PL-PCO-OPMR) to DME/methanol/power is proposed. • Exergeo-economic analysis is adopted to disclose the performance of systems. • Key technological conditions and parameters for PL-PCO-OPMR are optimized. • PL-PCO-OPMR shows high energy efficiency and low CO_2 emission. • PL-PCO-OPMR is an attractive way for high efficient and clean use of COG and CGG. - Abstract: Polygeneration system, typically involving chemicals/fuels and electricity co-production, is a promising technology for the sustainable development of energy and environment. In this study, a new polygeneration system based on coal and coke oven gas (COG) inputs for co-production of dimethyl ether (DME)/methanol and electricity is proposed. In the new system, an appropriate syngas for the synthesis of DME is from coal gasified gas (CGG) reforming of COG coupled with an oxygen-permeable membrane reactor, in which both COG and CGG reforming process and fuel combustion process are incorporated, which reduces exergy destruction in the whole reforming process. In order to obtain the best performance of CO_2 reduction, energy saving and economic benefit, the key operation parameters of the proposed process are analyzed and optimized. The new system is compared with the process based on CH_4/CO_2 dry reforming, in terms of exergy efficiency, exergy cost and CO_2 emissions. Through the new system, the exergy efficiency can be increased by 7.8%, the exergy cost can be reduced by 0.88 USD/GJ and the CO_2 emission can be reduced by 0.023 kg/MJ. These results suggest that the polygeneration system from CGG and COG partial catalytic oxidation coupling with an oxygen-permeable membrane reactor (PL-PCO-OPMR) would be a more attractive way for highly efficient and clean use of CGG and COG.

  5. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 2 2010-07-01 2010-07-01 false National primary and secondary ambient air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section 50.11 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS NATIONAL...

  6. Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Viktor A Utsal

    2007-03-01

    Full Text Available Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10 at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic and 2,4,6-trihydroxybenzoic (phloroglucinic acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol. In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxybenzoic acid (depside. However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol, but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin, or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed.

  7. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    Science.gov (United States)

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; Kroll, Jesse H.; Peng, Zhe; Brune, William H.; Jimenez, Jose L.

    2016-03-01

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen-Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m-3 when LVOC fate corrected) compared to daytime (average 0.9 µg m-3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic

  8. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    Directory of Open Access Journals (Sweden)

    B. B. Palm

    2016-03-01

    Full Text Available An oxidation flow reactor (OFR is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen–Rocky Mountain Biogenic Aerosol Study field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq. atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m−3 when LVOC fate corrected compared to daytime (average 0.9 µg m−3 when LVOC fate corrected, with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70, similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production

  9. Development of Green Pavement for Reducing Oxides of Nitrogen (NOx in the Ambient Air

    Directory of Open Access Journals (Sweden)

    Kania Dewi

    2016-05-01

    Full Text Available The transportation sector is the biggest contributor to air pollution in Indonesia, especially in metropolitan cities. Gases such as oxides of nitrogen (NOx are produced during the combustion of fossil fuels in the internal combustion of vehicle engines. Oxides of nitrogen such as nitric oxide (NO and nitrogen dioxide (NO2 are important air pollutants, because they cause significant harm to human health and play an important role in being precursors of other dangerous pollutants such as photochemical smog. One of the simple ways to reduce NOx concentrations is utilizing a catalytic process involving UV light and semiconductor particles such as TiO2. Illuminated TiO2 UV light is capable of producing an electron (e- and hole (h- pair, which initiates a chemical reaction that alters the NOx to become NO3- or NO2-. A field scale paving block reactor coated with TiO2 placed by the roadside was exposed to UV light using various exposure times. The results showed that the sample with a composition of 200 g/m2 TiO2 was capable of adsorbing NOx gas at an average rate of 0.0046 mg/m2/minute. Additional costs due to TiO2 coating for every square meter of paving are IDR 13,180.

  10. Improved oxidation of air pollutants in a non-thermal plasma

    International Nuclear Information System (INIS)

    Roland, U.; Holzer, F.; Kopinke, F.-D.

    2002-01-01

    The performance of non-thermal plasma (NTP) for the removal of organic air pollutants (especially in low concentrations) is improved by the introduction of ferroelectric and catalytically active materials into the discharge zone of an NTP reactor. Experiments with model systems (various contaminants and packed-bed materials) have shown that such a modification of a homogeneous gas-phase plasma can overcome the most serious restrictions of the NTP technique at its present state of the art: the incomplete total oxidation (i.e. the low selectivity to CO 2 ) and the energetic inefficiency. Placing a ferroelectric packed-bed material in the discharge zone was shown to result in a lowering of the energy input required. The main effects of plasma catalysis enabled by the introduction of a catalytically active material were an enhanced conversion of pollutants and a higher CO 2 selectivity. These improvements are based on the presence of short-lived oxidising species in the inner volume of porous catalysts. Additionally, the formation of a reservoir of adsorbed oxidants in the NTP zone could be shown. The combination of both modifications (ferroelectric packed-bed materials and plasma catalysis) is a promising method to support the NTP-initiated oxidation of air pollutants

  11. Gas-phase advanced oxidation as an integrated air pollution control technique

    Directory of Open Access Journals (Sweden)

    Getachew A. Adnew

    2016-03-01

    Full Text Available Gas-phase advanced oxidation (GPAO is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8 and reduced sulfur compounds (e.g. H2S and CH3SH, removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

  12. Structural changes of noble metal catalysts during ignition and extinction of the partial oxidation of methane studied by advanced QEXAFS techniques

    DEFF Research Database (Denmark)

    Grunwaldt, Jan-Dierk; Beier, M.; Kimmerle, B.

    2009-01-01

    The dynamics of the ignition and extinction of the catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al2O3 and Pt/Al2O3 were studied in the subsecond timescale using quick-EXAFS with a novel cam-driven X-ray monochromator employing Si(111) and Si(311) crystals...... to discuss the potential and limitation of this technique in catalysis and related areas. With respect to the noble metal catalysed partial oxidation of methane, several interesting observations were made: structural changes during ignition were-independent of the chosen reaction conditions......-significantly faster than during the extinction of the reaction. The dynamic behavior of the catalysts was dependent on the flow conditions and the respective noble metal component(s). Higher reaction gas flow led to a faster ignition process. While the ignition over Pt-Rh/Al2O3 occurred at lower temperature than over...

  13. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite; Estudo de filme de grafeno/oxido de grafeno obtido por reducao quimica parcial do oxido de grafite

    Energy Technology Data Exchange (ETDEWEB)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H., E-mail: juliagascho@hotmail.com [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2014-07-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  14. Air oxidation of Zircaloy-4 in the 600-1000 °C temperature range: Modeling for ASTEC code application

    Science.gov (United States)

    Coindreau, O.; Duriez, C.; Ederli, S.

    2010-10-01

    Progress in the treatment of air oxidation of zirconium in severe accident (SA) codes are required for a reliable analysis of severe accidents involving air ingress. Air oxidation of zirconium can actually lead to accelerated core degradation and increased fission product release, especially for the highly-radiotoxic ruthenium. This paper presents a model to simulate air oxidation kinetics of Zircaloy-4 in the 600-1000 °C temperature range. It is based on available experimental data, including separate-effect experiments performed at IRSN and at Forschungszentrum Karlsruhe. The kinetic transition, named "breakaway", from a diffusion-controlled regime to an accelerated oxidation is taken into account in the modeling via a critical mass gain parameter. The progressive propagation of the locally initiated breakaway is modeled by a linear increase in oxidation rate with time. Finally, when breakaway propagation is completed, the oxidation rate stabilizes and the kinetics is modeled by a linear law. This new modeling is integrated in the severe accident code ASTEC, jointly developed by IRSN and GRS. Model predictions and experimental data from thermogravimetric results show good agreement for different air flow rates and for slow temperature transient conditions.

  15. Alternative materials for solid oxide fuel cells: Factors affecting air-sintering of chromite interconnections

    International Nuclear Information System (INIS)

    Chick, L.A.; Bates, J.L.

    1992-01-01

    The purpose of this research is to develop alternative materials for solid oxide fuel cell (SOFC) interconnections and electrodes with improved electrical, thermal and electrochemical properties. Another objective is to develop synthesis and fabrication processes for these materials whereby they can be consolidated in air into SOFC's. The approach is to (1) develop modifications of the current, state-of-the-art materials used in SOFC's, (2) minimize the number of cations used in the SOFC materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabrication and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component compositions and processing on those reactions

  16. Thin porous indium tin oxide nanoparticle films: effects of annealing in vacuum and air

    International Nuclear Information System (INIS)

    Ederth, J.; Hultaaker, A.; Niklasson, G.A.; Granqvist, C.G.; Heszler, P.; Doorn, A.R. van; Jongerius, M.J.; Burgard, D.

    2005-01-01

    Electrical and optical properties were investigated in porous thin films consisting of In 2 O 3 :Sn (indium tin oxide; ITO) nanoparticles. The temperature-dependent resistivity was successfully described by a fluctuation-induced tunneling model, indicating a sample morphology dominated by clusters of ITO nanoparticles separated by insulating barriers. An effective-medium model, including the effect of ionized impurity scattering, was successfully fitted to measured reflectance and transmittance. Post-deposition treatments were carried out at 773 K for 2 h in both air and vacuum. It is shown that vacuum annealing increases either the barrier width or the area between two conducting clusters in the samples and, furthermore, an extra optical absorption occurs close to the band gap. A subsequent air annealing then reduces the effect of the barriers on the electrical properties and diminishes the absorption close to the band gap. (orig.)

  17. Axial Changes of Catalyst Structure and Temperature in a Fixed-Bed Microreactor During Noble Metal Catalysed Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Hannemann, S.; Grunwaldt, Jan-Dierk; Kimmerle, B.

    2009-01-01

    The catalytic partial oxidation of methane (CPO) over flame-made 2.5%Rh-2.5%Pt/Al2O3 and 2.5%Rh/Al2O3 in 6%CH4/3%O-2/He shows the potential of in situ studies using miniaturized fixed-bed reactors, the importance of spatially resolved studies and its combination with infrared thermography and on-...

  18. Photocatalytic activity of silver oxide capped Ag nanoparticles constructed by air plasma irradiation

    Science.gov (United States)

    Fang, Yingcui; Wu, Qingmeng; Li, Huanhuan; Zhang, Bing; Yan, Rong; Chen, Junling; Sun, Mengtao

    2018-04-01

    We construct a kind of structure of silver oxide capped silver nanoparticles (AgNPs) by cost-efficient air plasma irradiation, and study its visible-light driven photocatalytic activity (PA). By controlling the oxidization time, the relationship between the intensity of the localized surface plasmon resonance (LSPR) and the PA is well established. The PA reaches the maximum when the LSPR of AgNPs is nearly completely damped (according to absorption spectra); however, under this condition, the LSPR still works, confirmed with the high efficient selective transformation of p-Aminothiophenol (PATP) to p, p'-dimercaptoazobenzene (DMAB) under visible light. The mechanism of the LSPR damping induced PA improvement is discussed. We not only provide a cost-efficient approach to construct a LSPR strong damping structure but also promote the understanding of LSPR strong damping and its relationship with photocatalysis.

  19. A Bioinspired Organocatalytic Cascade for the Selective Oxidation of Amines under Air.

    Science.gov (United States)

    Largeron, Martine; Fleury, Maurice-Bernard

    2017-05-17

    A bioinspired organocatalytic cascade reaction for the selective aerobic oxidative cross-coupling of primary amines to imines is described. This approach takes advantages of commercially available pyrogallol monomeric precursor to deliver low loadings of natural purpurogallin in situ, under air. This is further engaged in a catalytic process with the amine substrate affording, under single turnover, the active biomimetic quinonoid organocatalyst and the homocoupled imine intermediate, which is then converted into cross-coupled imine after dynamic transimination. This organocatalytic cascade inspired by both purpurogallin biosynthesis and copper amine oxidases allows the aerobic oxidation of non-activated primary amines that non-enzymatic organocatalysts were not able to accomplish alone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Creep performance of oxide ceramic fiber materials at elevated temperature in air and in steam

    Science.gov (United States)

    Armani, Clinton J.

    Structural aerospace components that operate in severe conditions, such as extreme temperatures and detrimental environments, require structural materials that have superior long-term mechanical properties and that are thermochemically stable over a broad range of service temperatures and environments. Ceramic matrix composites (CMCs) capable of excellent mechanical performance in harsh environments are prime candidates for such applications. Oxide ceramic materials have been used as constituents in CMCs. However, recent studies have shown that high-temperature mechanical performance of oxide-oxide CMCs deteriorate in a steam-rich environment. The degradation of strength at elevated temperature in steam has been attributed to the environmentally assisted subcritical crack growth in the oxide fibers. Furthermore, oxide-oxide CMCs have shown significant increases in steady-state creep rates in steam. The present research investigated the effects of steam on the high-temperature creep and monotonic tension performance of several oxide ceramic materials. Experimental facilities were designed and configured, and experimental methods were developed to explore the influence of steam on the mechanical behaviors of ceramic fiber tows and of ceramic bulk materials under temperatures in the 1100--1300°C range. The effects of steam on creep behavior of Nextel(TM)610 and Nextel(TM)720 fiber tows were examined. Creep rates at elevated temperatures in air and in steam were obtained for both types of fibers. Relationships between creep rates and applied stresses were modeled and underlying creep mechanisms were identified. For both types of fiber tows, a creep life prediction analysis was performed using linear elastic fracture mechanics and a power-law crack velocity model. These results have not been previously reported and have critical design implications for CMC components operating in steam or near the recommended design limits. Predictions were assessed and validated via

  1. Oxidation of volatile organic vapours in air by solid potassium permanganate.

    Science.gov (United States)

    Mahmoodlu, Mojtaba Ghareh; Hartog, Niels; Majid Hassanizadeh, S; Raoof, Amir

    2013-06-01

    Volatile organic compounds (VOCs) may frequently contaminate groundwater and pose threat to human health when migrating into the unsaturated soil zone and upward to the indoor air. The kinetic of chemical oxidation has been investigated widely for dissolved VOCs in the saturated zone. But, so far there have been few studies on the use of in situ chemical oxidation (ISCO) of vapour phase contaminants. In this study, batch experiments were carried out to evaluate the oxidation of trichloroethylene (TCE), ethanol, and toluene vapours by solid potassium permanganate. Results revealed that solid potassium permanganate is able to transform the vapour of these compounds into harmless oxidation products. The degradation rates for TCE and ethanol were higher than for toluene. The degradation process was modelled using a kinetic model, linear in the gas concentration of VOC [ML(-3)] and relative surface area of potassium permanganate grains (surface area of potassium permanganate divided by gas volume) [L(-1)]. The second-order reaction rate constants for TCE, ethanol, and toluene were found to be equal to 2.0×10(-6) cm s(-1), 1.7×10(-7) cm s(-1), and 7.0×10(-8) cm s(-1), respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Partially Fluorinated Solvent as a co-solvent for the Non-aqueous Electrolyte of Li/air Battery

    Science.gov (United States)

    2010-11-11

    ether ( MFE ) and tris(2,2,2-trifluoroethyl) phosphite (TTFP), respectively, as a co-solvent for the non-aqueous electrolyte of Li–air battery. Results...fluorinated solvents on the discharge performance of Li–air bat- tery. For this purpose, we here selectmethyl nonafluorobutyl ether ( MFE ) and tris...196, (2011) pgs. 2867-2870 14. ABSTRACT In this workwestudy methyl nonafluorobutyl ether ( MFE ) and tris(2,2,2-trifluoroethyl) phosphite (TTFP

  3. Graphene oxide papers with high water adsorption capacity for air dehumidification.

    Science.gov (United States)

    Liu, Renlong; Gong, Tao; Zhang, Kan; Lee, Changgu

    2017-08-29

    Graphene oxide (GO) has shown a high potential to adsorb and store water molecules due to the oxygen-containing functional groups on its hydrophilic surface. In this study, we characterized the water absorbing properties of graphene oxide in the form of papers. We fabricated three kinds of graphene oxide papers, two with rich oxygen functional groups and one with partial chemical reduction, to vary the oxygen/carbon ratio and found that the paper with high oxygen content has higher moisture adsorption capability. For the GO paper with reduction, the overall moisture absorbance was reduced. However, the absorbance at high humidity was significantly improved due to direct formation of multilayer water vapor in the system, which derived from the weak interaction between the adsorbent and the adsorbate. To demonstrate one application of GO papers as a desiccant, we tested grape fruits with and without GO paper. The fruits with a GO paper exhibited longer-term preservation with delayed mold gathering because of desiccation effect from the paper. Our results suggest that GO will find numerous practical applications as a desiccant and is a promising material for moisture desiccation and food preservation.

  4. Oxygen reduction reaction catalysts of manganese oxide decorated by silver nanoparticles for aluminum-air batteries

    International Nuclear Information System (INIS)

    Sun, Shanshan; Miao, He; Xue, Yejian; Wang, Qin; Li, Shihua; Liu, Zhaoping

    2016-01-01

    In this paper, the hybrid catalysts of manganese oxide decorated by silver nanoparticles (Ag-MnO x ) are fully investigated and show the excellent oxygen reduction reaction (ORR) activity. The Ag-MnO 2 is synthesized by a facile strategy of the electroless plating of silver on the manganese oxide. The catalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Then, the ORR activities of the catalysts are systematically investigated by the rotating disk electrode (RDE) and aluminum-air battery technologies. The Ag nanoparticles with the diameters at about 10 nm are anchored on the surface of α-MnO 2 and a strong interaction between Ag and MnO 2 components in the hybrid catalyst are confirmed. The electrochemical tests show that the activity and stability of the 50%Ag-MnO 2 composite catalyst (the mass ratio of Ag/MnO 2 is 1:1) toward ORR are greatly enhanced comparing with single Ag or MnO 2 catalyst. Moreover, the peak power density of the aluminum-air battery with 50%Ag-MnO 2 can reach 204 mW cm −2 .

  5. Inkjet Impregnation for Tailoring Air Electrode Microstructure to Improve Solid Oxide Cells Performance

    KAUST Repository

    Da’as, Eman H.

    2015-09-30

    The urge to lower the operating temperature of solid oxide cells (SOCs) to the intermediate ranges between 500-700°C motivated the research into impregnation processes, which offer highly efficient SOC air electrodes at low operating temperatures. Lack of controllability and reproducibility of this technique in the conventional way is still considered as an inadequacy for industrialization since it is performed manually. Therefore, inkjet-printing technology was proposed as an adequate approach to perform scalable and controllable impregnation for SOC air electrodes, which in turn leads to low operating temperatures. Composite LSM-ionic conductive air electrodes of weight ratio 1:2 were fabricated by inkjet impregnation of lanthanum strontium manganite (La0.8Sr0.2MnO3) precursor nitrates onto a porous ionic conductive backbone structure. First, porous yttria stabilized zirconia (8YSZ) substrates prepared by tape casting were used to study the influence of the printing parameters on the lateral dispersion and penetration of LSM ink inside the pores. XRD analysis confirmed the formation of LSM phase after calcination at 800°C for 2 h, while SEM revealed the formation of LSM nanostructures. It has been found by optical microscope observations that the spacing between the drops and the substrate temperature have a significant role in controlling the printing process. Next, the optimized printing parameters were applied in the inkjet impregnation of the LSM ink into porous YSZ electrodes that were spin coated on both sides of dense YSZ layers. LSM-YSZ composite air electrodes achieved an area specific resistance (ASR) of around 0.29 Ω.cm2 at 700°C. The performance of LSM-YSZ composite electrodes was influenced by the microstructure and the thickness, and by the electrode/electrolyte interface characteristics. As a result, the enhancement in LSM-YSZ composite electrode performance was observed due to the better percolation in LSM, YSZ and oxygen diffusion. Finally

  6. Impact of Air Frying on Cholesterol and Fatty Acids Oxidation in Sardines: Protective Effects of Aromatic Herbs.

    Science.gov (United States)

    Ferreira, Fernanda S; Sampaio, Geni R; Keller, Laura M; Sawaya, Alexandra C H F; Chávez, Davy W H; Torres, Elizabeth A F S; Saldanha, Tatiana

    2017-12-01

    The high temperatures used to fry fish may induce thermo-oxidation of cholesterol, forming cholesterol oxidation products (COPs). COPs have been associated to coronary heart diseases, atherosclerosis, and other chronic diseases. Air fryers are an alternative thermal process technology to fry foods without oil, and are considered a healthier cooking method. This study is the 1st to evaluate the formation of COPs and the degradation of polyunsaturated fatty acids (PUFAs) in air-fried sardine fillets. Furthermore, we evaluated the effect of fresh herbs added as natural antioxidants to sardines subjected to air frying. Parsley (Petroselinum crispum), chives (Allium schoenoprasum L.), and a mixture of both herbs (cheiro-verde) were added in quantities of 0%, 2%, and 4%. Air frying significantly decreased the content of essential PUFAs, and increased the levels of COPs from 61.2 (raw) to 283 μg/g (P addition of 4% of cheiro-verde in air-fried sardines presented the best protective effect against lipid oxidation. Fish is an important source of essential lipids. However, oxidized cholesterol products, which are formed during thermal processing, are potential hazards to human health. Air fryers present an alternative thermal process for frying food without oil, and this method of cooking is considered to be more convenient and healthier This study shows that the air frying increased the formation of cholesterol oxidation products and decreased the essential polyunsaturated fatty acids in sardine fillets. However, the lipid oxidation is significantly reduced by adding fresh herbs, such as parsley (Petroselinum crispum), chives (Allium schoenoprasum L.), or a mixture of both herbs (cheiro-verde) that are natural antioxidants. © 2017 Institute of Food Technologists®.

  7. Effect of partial oxygen pressure on physicochemical properties of Kh18N10T steel at isothermal oxidation

    International Nuclear Information System (INIS)

    Alekseev, V.N.; Oshe, E.K.; Fokin, M.N.; Bogdanova, S.V.; Loskutov, A.I.

    1990-01-01

    Auger-electron spectroscopy, photoelectric polarization, conductometry methods have been used to analyze chemical and defect composition of surface oxide layers, formed on stainless steel Kh18N10T in vacuum (10 -9 - 10 -2 torr) and at temperatures 593-673 K. The boundary conditions of manifestation of extermal behaviour of the dependence of the surface oxide growth rate at isothermal oxidation of this steel are determined. The relation between passivation properties of the surface oxide and the magnitude of the edge angle of the surface wetting with molten tin is revealed

  8. The oxidative stress and antioxidant responses of Litopenaeus vannamei to low temperature and air exposure.

    Science.gov (United States)

    Xu, Zihan; Regenstein, Joe M; Xie, Dandan; Lu, Wenjing; Ren, Xingchen; Yuan, Jiajia; Mao, Linchun

    2018-01-01

    Low temperature and air exposure were the key attributes for waterless transportation of fish and shrimp. In order to investigate the oxidative stress and antioxidant responses of the live shrimp Litopenaeus vannamei in the mimic waterless transportation, live shrimp were cooled at 13 °C for 3 min, stored in oxygen at 15 °C for 12 h, and then revived in water at 25 °C. The survival rate of shrimp under this waterless transportation system was over 86.67%. The ultrastructure of hepatopancreas cells were observed while activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione peroxidase (GSH-Px), antisuperoxide anion free radicals (ASAFR), total antioxidant capacity (TAOC), reactive oxygen species (ROS) production, content of malondialdehyde (MDA) and relative mRNA expressions of CAT and GSH-Px in the hemolymph and hepatopancreas were determined. Slight distortions of some organelles in hepatopancreas cells was reversible upon the shrimp revived from the cold shock. The activities of SOD, POD, CAT, GSH-Px, TAOC, ROS production and relative mRNA expressions of CAT and GSH-Px increased following the cold shock and reached peak levels after 3 or 6 h of storage, and then decreased gradually. There was no significant difference between the fresh and the revived shrimp in SOD, POD, GSH-Px, TAOC, ROS, MDA and relative mRNA expressions of CAT and GSH-Px. The oxidative stress and antioxidant responses were tissue-specific because hepatopancreas seemed to have a greater ability to defend against organelle damage and was more sensitive to stress than hemolymph based on the results of SOD activity, MDA content and GSH-Px mRNA expression. These results revealed that low temperature and air exposure caused significant oxidative and antioxidant responses, but did not lead to irreversible damages in this waterless system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Particulate matter air pollution causes oxidant-mediated increase in gut permeability in mice

    Directory of Open Access Journals (Sweden)

    Keshavarzian Ali

    2011-06-01

    Full Text Available Abstract Background Exposure to particulate matter (PM air pollution may be an important environmental factor leading to exacerbations of inflammatory illnesses in the GI tract. PM can gain access to the gastrointestinal (GI tract via swallowing of air or secretions from the upper airways or mucociliary clearance of inhaled particles. Methods We measured PM-induced cell death and mitochondrial ROS generation in Caco-2 cells stably expressing oxidant sensitive GFP localized to mitochondria in the absence or presence of an antioxidant. C57BL/6 mice were exposed to a very high dose of urban PM from Washington, DC (200 μg/mouse or saline via gastric gavage and small bowel and colonic tissue were harvested for histologic evaluation, and RNA isolation up to 48 hours. Permeability to 4kD dextran was measured at 48 hours. Results PM induced mitochondrial ROS generation and cell death in Caco-2 cells. PM also caused oxidant-dependent NF-κB activation, disruption of tight junctions and increased permeability of Caco-2 monolayers. Mice exposed to PM had increased intestinal permeability compared with PBS treated mice. In the small bowel, colocalization of the tight junction protein, ZO-1 was lower in the PM treated animals. In the small bowel and colon, PM exposed mice had higher levels of IL-6 mRNA and reduced levels of ZO-1 mRNA. Increased apoptosis was observed in the colon of PM exposed mice. Conclusions Exposure to high doses of urban PM causes oxidant dependent GI epithelial cell death, disruption of tight junction proteins, inflammation and increased permeability in the gut in vitro and in vivo. These PM-induced changes may contribute to exacerbations of inflammatory disorders of the gut.

  10. Nighttime oxidation of surfactants at the air-water interface: effects of chain length, head group and saturation

    Science.gov (United States)

    Sebastiani, Federica; Campbell, Richard A.; Rastogi, Kunal; Pfrang, Christian

    2018-03-01

    Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air-water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA), palmitoleic acid (POA), methyl oleate (MO) and stearic acid (SA) to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR) to determine the reaction kinetics of organic monolayers with NO3 at the air-water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7) × 10-8, (2.4±0.5) × 10-8and (3.3±0.6) × 10-8 cm2 molecule-1 s-1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5) × 10-3, (1.7±0.3) × 10-3 and (2.1±0.4) × 10-3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1) × 10-12 cm2 molecule-1 s-1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1) × 10-7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air-water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher than that of O3. Furthermore, the relative contributions of NO3 and O3 to the oxidative

  11. Effect of aging on the concentrations of nitrous oxide in exhaled air

    Energy Technology Data Exchange (ETDEWEB)

    Mitsui, T.; Shimaoka, K.; Miyamura, M. [Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya (Japan); Kato, N. [Chukyo Women`s University, Obu (Japan)

    1997-12-03

    Trace gases in exhaled air have been used as a simple means of assessing metabolic reactions. The investigations of trace gases derived from bacteria in human exhalation are usually hydrogen (H{sub 2}) or methane (CH{sub 4}). On the other hand, nitrous oxide (N{sub 2}O) is also derived from microorganisms, especially denitrifying bacteria. Although many kinds of denitrifying bacteria have been isolated on and in the human body, there has been few concerning N{sub 2}O. We studied 222 healthy people from the age of 5 to 85 years. The analysis of N{sub 2}O in exhaled air was carried out by a infrared-photoacoustic (IR-PAS) analyzer. It was found that N{sub 2}0 ranged from 0 to 1670 ppbv in exhaled air and that 59% (131) of the subjects were producers N{sub 2}O. A highly significant relationship was observed between age and concentrations of N{sub 2}O (r=0.40, P<0.01). The rate of production in young children and in the aged was significantly higher than that in adults aged 20-39 years (P<0.01), and less than 30% were producers during puberty. The change of normal microflora and in human body with aging may have caused the significant relationship between age and emissions of N{sub 2}O

  12. High-temperature air oxidation of E110 and Zr-1%Nb alloys claddings with coatings

    International Nuclear Information System (INIS)

    Kuprin, A.S.; Belous, V.A.; Voyevodin, V.N.; Bryk, V.V.; Vasilenko, R.L.; Ovcharenko, V.D.; Tolmachova, G.N.; V'yugov, P.N.

    2014-01-01

    Results of experimental study of the influence of protective vacuum-arc claddings on the base of compounds zirconium-chromium and of its nitrides on air oxidation resistance at temperatures 660, 770, 900, 1020, 1100 deg C during 3600 s. of tubes produced of zirconium alloys E110 and Zr-1%Nb (calcium-thermal alloy of Ukrainian production) are presented. Change of hardness, the width of oxide layer and depth of oxygen penetration into alloys from the side of coating and without coating are investigated by the methods of nanoindentation and by scanning electron microscopy. It is shown that the thickness of oxide layer in zirconium alloys at temperatures 1020 and 1100 deg C from the side of the coating doesn't exceed 5 μm, and from the unprotected side reaches the value of ≥ 120 μm with porous and rough structure. Tubes with coatings save their shape completely independently of the type of alloy; tubes without coatings deform with the production of through cracks

  13. Ruthenium and Platinum Catalysts Supported on Ce, Zr, Pr-O Mixed Oxides Prepared by Soft Chemistry for Acetic Acid Wet Air Oxidation

    Czech Academy of Sciences Publication Activity Database

    Mikulová, Jana; Rossignol, S.; Barbier Jr., J.; Mesnard, D.; Kappenstein, C.; Duprez, D.

    2007-01-01

    Roč. 72, 1-2 (2007), s. 1-10 ISSN 0926-3373 Institutional research plan: CEZ:AV0Z40720504 Keywords : sol-gel * catalytic wet air oxidation * acetic acid Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.651, year: 2007

  14. Neuropeptides and nitric oxide synthase in the gill and the air-breathing organs of fishes.

    Science.gov (United States)

    Zaccone, Giacomo; Mauceri, Angela; Fasulo, Salvatore

    2006-05-01

    Anatomical and histochemical studies have demonstrated that the bulk of autonomic neurotransmission in fish gill is attributed to cholinergic and adrenergic mechanisms (Nilsson. 1984. In: Hoar WS, Randall DJ, editors. Fish physiology, Vol. XA. Orlando: Academic Press. p 185-227; Donald. 1998. In: Evans DH, editor. The physiology of fishes, 2nd edition. Boca Raton: CRC Press. p 407-439). In many tissues, blockade of adrenergic and cholinergic transmission results in residual responses to nerve stimulation, which are termed NonAdrenergic, NonCholinergic (NANC). The discovery of nitric oxide (NO) has provided a basis for explaining many examples of NANC transmissions with accumulated physiological and pharmacological data indicating its function as a primary NANC transmitter. Little is known about the NANC neurotransmission, and studies on neuropeptides and NOS (Nitric Oxide Synthase) are very fragmentary in the gill and the air-breathing organs of fishes. Knowledge of the distribution of nerves and effects of perfusing agonists may help to understand the mechanisms of perfusion regulation in the gill (Olson. 2002. J Exp Zool 293:214-231). Air breathing as a mechanism for acquiring oxygen has evolved independently in several groups of fishes, necessitating modifications of the organs responsible for the exchange of gases. Aquatic hypoxia in freshwaters has been probably the more important selective force in the evolution of air breathing in vertebrates. Fishes respire with gills that are complex structures with many different effectors and potential control systems. Autonomic innervation of the gill has received considerable attention. An excellent review on branchial innervation includes Sundin and Nilsson's (2002. J Exp Zool 293:232-248) with an emphasis on the anatomy and basic functioning of afferent and efferent fibers of the branchial nerves. The chapters by Evans (2002. J Exp Zool 293:336-347) and Olson (2002) provide new challenges about a variety of

  15. Oxidation in air of two refractory alloys (Nicral D and Hastelloy X) at 900 and 1100 deg. C

    International Nuclear Information System (INIS)

    Sannier, J.; Dominget, R.; Darras, R.

    1960-01-01

    The oxidation in air of two refractory alloys (Nicral D and Hastelloy X) has been studied at 900 and 1100 deg. C, by means of recording thermo-balances and microscopic cross section examination. At 900 deg. C, the surface oxidation rates of the two alloys are quite similar, but at 1100 deg. C the alloy Nicral D oxidizes faster than the alloy Hastelloy X. On the other hand, after heating at 1100 deg. C for 150 hours, Nicral D shows both intergranular oxidation and a small amount of internal oxidation, whereas Hastelloy X is especially subject to internal oxidation. In addition, two descaling methods were compared: an electrolytic method, in a sodium hydroxide-sodium carbonate bath, and a chemical method using a sodium nitrate-sodium peroxide bath; the latter appears suitable only for Hastelloy X. Reprint of a paper published in Journal of nuclear materials, 3, p. 213-225, 1959 [fr

  16. Detection and removal of impurities in nitric oxide generated from air by pulsed electrical discharge.

    Science.gov (United States)

    Yu, Binglan; Blaesi, Aron H; Casey, Noel; Raykhtsaum, Grigory; Zazzeron, Luca; Jones, Rosemary; Morrese, Alexander; Dobrynin, Danil; Malhotra, Rajeev; Bloch, Donald B; Goldstein, Lee E; Zapol, Warren M

    2016-11-30

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation without dilating the systemic circulation. However, the current NO/N 2 cylinder delivery system is cumbersome and expensive. We developed a lightweight, portable, and economical device to generate NO from air by pulsed electrical discharge. The objective of this study was to investigate and optimize the purity and safety of NO generated by this device. By using low temperature streamer discharges in the plasma generator, we produced therapeutic levels of NO with very low levels of nitrogen dioxide (NO 2 ) and ozone. Despite the low temperature, spark generation eroded the surface of the electrodes, contaminating the gas stream with metal particles. During prolonged NO generation there was gradual loss of the iridium high-voltage tip (-90 μg/day) and the platinum-nickel ground electrode (-55 μg/day). Metal particles released from the electrodes were trapped by a high-efficiency particulate air (HEPA) filter. Quadrupole mass spectroscopy measurements of effluent gas during plasma NO generation showed that a single HEPA filter removed all of the metal particles. Mice were exposed to breathing 50 parts per million of electrically generated NO in air for 28 days with only a scavenger and no HEPA filter; the mice did not develop pulmonary inflammation or structural changes and iridium and platinum particles were not detected in the lungs of these mice. In conclusion, an electric plasma generator produced therapeutic levels of NO from air; scavenging and filtration effectively eliminated metallic impurities from the effluent gas. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Optimization of BSCF-SDC composite air electrode for intermediate temperature solid oxide electrolyzer cell

    International Nuclear Information System (INIS)

    Heidari, Dorna; Javadpour, Sirus; Chan, Siew Hwa

    2017-01-01

    Highlights: • Effect of BSCF-SDC composite air electrode on SOEC electrochemical performance. • Effects on performance of BSCF-SDC air electrode, fuel humidity and temperature. • Desired IT-SOEC performance by compositing the BSCF air electrode with SDC. - Abstract: Solid oxide electrolyzer cells (SOECs) are devises which recently have attracted lots of attention due to their advantages. Their high operating temperature leads to mechanical compatibility issues such as thermal expansion mismatch between layers of material in the cell. The aim of this study is to mitigate the issue of thermal expansion mismatch between Ba_0_._5Sr_0_._5Co_0_._8Fe_0_._2O_3_−_δ (BSCF) and samaria doped ceria, Sm_0_._2Ce_0_._8O_1_._9 (SDC), enhance the triple-phase boundaries and improve the adhesion of the electrode to the electrolytes, hence improve the cell performance. To make BSCF more thermo-mechanically compatible with the SDC electrolyte, the formation of a composite electrode by introducing SDC as the compositing material is proposed. In this study, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.% of commercial SDC powder was mixed with BSCF powder, prepared by sol-gel method, to make the composite air electrode. After successfully synthesizing the BSCF-SDC/YSZ-SDC/Ni-YSZ electrolyzer cell, the electrochemical performance was tested for the intermediate-temperature SOEC (IT-SOEC), over the temperature range of 650–800 °C. The microstructure of each sample was studied by field emission electron microscopy (FESEM, JEOL, JSM 6340F) for possible pin holes. The result of this study proves that the sample with 20% SDC-80% BSCF shows the highest performance among the investigated cells.

  18. FINAL REPORT on Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Chang H. Oh; Eung S. Kim; Hee C. NO; Nam Z. Cho

    2011-01-01

    The U.S. Department of Energy is performing research and development that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP)/Generation IV very high temperature reactor (VHTR). Phenomena Identification and Ranking studies to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important. Consequently, the development of advanced air ingress-related models and verification & validation are of very high priority for the NGNP Project. Following a loss of coolant and system depressurization incident, air ingress will occur through the break, leading to oxidation of the in-core graphite structure and fuel. This study indicates that depending on the location and the size of the pipe break, the air ingress phenomena are different. In an effort to estimate the proper safety margin, experimental data and tools, including accurate multidimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model are required. It will also require effective strategies to mitigate the effects of oxidation, eventually. This 3-year project (FY 2008–FY 2010) is focused on various issues related to the VHTR air-ingress accident, including (a) analytical and experimental study of air ingress caused by density-driven, stratified, countercurrent flow, (b) advanced graphite oxidation experiments, (c) experimental study of burn-off in the core bottom structures, (d) structural tests of the oxidized core bottom structures, (e) implementation of advanced models developed during the previous tasks into the GAMMA code, (f) full air ingress and oxidation mitigation analyses, (g) development of core neutronic models, (h) coupling of the core neutronic and thermal hydraulic models, and (i) verification and validation of the coupled models.

  19. Advanced STEM/EDX investigation on an oxide scale thermally grown on a high-chromium iron–nickel alloy under very low oxygen partial pressure

    International Nuclear Information System (INIS)

    Latu-Romain, L.; Madi, Y.; Mathieu, S.; Robaut, F.; Petit, J.-P.; Wouters, Y.

    2015-01-01

    Highlights: • A scale grown on a high-chromium iron–nickel alloy under low oxygen partial pressure was studied. • STEM-EDX maps at high resolution on a transversal thin lamella have been conducted. • The real complexity of the oxide layer has been highlighted. • These results explain the elevated number of semiconducting contributions. - Abstract: A thermal oxide scale has been grown on a high-chromium iron-nickel alloy under very low oxygen partial pressure (1050 °C, 10"−"1"0 Pa). In this paper, a special attention has been paid to morphological and chemical characterizations of the scale by scanning transmission electron microscopy and energy dispersive X-ray analysis at high resolution on a cross-section thin lamella beforehand prepared by using a combined focused ion beam/scanning electron microscope instrument. The complexity of the oxide layer is highlighted, and the correlation between the present results and the ones of a photoelectrochemical study is discussed.

  20. Steam Methane Reformation Testing for Air-Independent Solid Oxide Fuel Cell Systems

    Science.gov (United States)

    Mwara, Kamwana N.

    2015-01-01

    Recently, NASA has been looking into utilizing landers that can be propelled by LOX-CH (sub 4), to be used for long duration missions. Using landers that utilize such propellants, also provides the opportunity to use solid oxide fuel cells as a power option, especially since they are able to process methane into a reactant through fuel reformation. One type of reformation, called steam methane reformation, is a process to reform methane into a hydrogen-rich product by reacting methane and steam (fuel cell exhaust) over a catalyst. A steam methane reformation system could potentially use the fuel cell's own exhaust to create a reactant stream that is hydrogen-rich, and requires less internal reforming of the incoming methane. Also, steam reformation may hold some advantages over other types of reforming, such as partial oxidation (PROX) reformation. Steam reformation does not require oxygen, while up to 25 percent can be lost in PROX reformation due to unusable CO (sub 2) reformation. NASA's Johnson Space Center has conducted various phases of steam methane reformation testing, as a viable solution for in-space reformation. This has included using two different types of catalysts, developing a custom reformer, and optimizing the test system to find the optimal performance parameters and operating conditions.

  1. Air pollution and risk of hospitalization for epilepsy: the role of farm use of nitrogen fertilizers and emissions of the agricultural air pollutant, nitrous oxide

    Directory of Open Access Journals (Sweden)

    Keith Fluegge

    Full Text Available ABSTRACT The link between various air pollutants and hospitalization for epilepsy has come under scrutiny. We have proposed that exposure to air pollution and specifically the pervasive agricultural air pollutant and greenhouse gas, nitrous oxide (N2O, may provoke susceptibility to neurodevelopmental disorders. Evidence supports a role of N2O exposure in reducing epileptiform seizure activity, while withdrawal from the drug has been shown to induce seizure-like activity. Therefore, we show here that the statewide use of anthropogenic nitrogen fertilizers (the most recognized causal contributor to environmental N2O burden is significantly negatively associated with hospitalization for epilepsy in all three pre-specified hospitalization categories, even after multiple pollutant comparison correction (p<.007, while the other identified pollutants were not consistently statistically significantly associated with hospitalization for epilepsy. We discuss potential neurological mechanisms underpinning this association between air pollutants associated with farm use of anthropogenic nitrogen fertilizers and hospitalization for epilepsy.

  2. GENERATION, TRANSPORT AND DEPOSITION OF TUNGSTEN-OXIDE AEROSOLS AT 1000 C IN FLOWING AIR-STEAM MIXTURES.

    Energy Technology Data Exchange (ETDEWEB)

    GREENE,G.A.; FINFROCK,C.C.

    2001-10-01

    Experiments were conducted to measure the rates of oxidation and vaporization of pure tungsten rods in flowing air, steam and air-steam mixtures in laminar flow. Also measured were the downstream transport of tungsten-oxide condensation aerosols and their region of deposition, including plateout in the superheated flow tube, rainout in the condenser and ambient discharge which was collected on an array of sub-micron aerosol filters. The nominal conditions of the tests, with the exception of the first two tests, were tungsten temperatures of 1000 C, gas mixture temperatures of 200 C and wall temperatures of 150 C to 200 C. It was observed that the tungsten oxidation rates were greatest in all air and least in all steam, generally decreasing non-linearly with increasing steam mole fraction. The tungsten oxidation rates in all air were more than five times greater than the tungsten oxidation rates in all steam. The tungsten vaporization rate was zero in all air and increased with increasing steam mole fraction. The vaporization rate became maximum at a steam mole fraction of 0.85 and decreased thereafter as the steam mole fraction was increased to unity. The tungsten-oxide was transported downstream as condensation aerosols, initially flowing upwards from the tungsten rod through an 18-inch long, one-inch diameter quartz tube, around a 3.5-inch radius, 90{sup o} bend and laterally through a 24-inch horizontal run. The entire length of the quartz glass flow path was heated by electrical resistance clamshell heaters whose temperatures were individually controlled and measured. The tungsten-oxide plateout in the quartz tube was collected, nearly all of which was deposited at the end of the heated zone near the entrance to the condenser which was cold. The tungsten-oxide which rained out in the condenser as the steam condensed was collected with the condensate and weighed after being dried. The aerosol smoke which escaped the condenser was collected on the sub

  3. Experimental studies of applicability of the wet air oxidation for purification liquid radioactive waste

    International Nuclear Information System (INIS)

    Sergienko, V. I.; Dobrzansky, V. G.

    2005-01-01

    The scheme of handling with liquid radioactive waste (LRW) accepted to exploitation at atomic electric station (AWS) is often connected with evaporating technologies. In this case vat residues of evaporating systems with activity 10 5 -10 6 Bq/1 and containing to 200-300 g/1 of salts are delivered up to LRW storages for lasting keeping. This schema does not correlate to the modern safety standards of handling with LRW, therefore at present numerous works are being carried on including those using technology of accumulated vat residues processing. Some successful experiments on sorption purification of high-salt LRW from cesium radionuclides giving the principal contribution into the total activity of a certain LRW are known. Unfortunately, attempts of sorption purification of the vat residues from other long-lived radionuclides (mainly from 60 Co-radionuclide) were unsuccessful up to the present time. It is found with the fact that the vat residues contain a considerable amount of complexing agent producing stable complexes with transition metal radionuclides including those of 60 Co. Extreme oxidation of the vat residues for decomposition of radioactive organic complexes is one of the solutions of this problem. The works related to oxidation of LRW including the AES vat residues with ozone, hydrogen peroxide as well as photo catalytic and electrochemical oxidation are known, however, possibilities of wet air oxidation (WAO) for LRW processing are not studied till the present time. Condition for decomposition of cobalt complex compounds and necessary excess of oxidizing agent may be easily attained with WAO usage. The necessary experiments were carried out at the experimental plant with the great interface surface (oxygen-solutions) equal to 400m -1 and 3 mm probe bed thickness. The heating time of the reactor to the working temperature 250 .deg. C did not exceed 50 seconds. 20... 50-fold oxidizer excess was achieved by the initial oxygen pressure into the reactor

  4. Observations concerning the particle-size of the oxidation products of uranium formed in air or in carbon dioxide

    International Nuclear Information System (INIS)

    Baque, P.; Leclercq, D.

    1964-01-01

    This report brings together the particle-size analysis results obtained on products formed by the oxidation or the ignition of uranium in moist air or dry carbon dioxide. The results bring out the importance of the nature of the oxidising atmosphere, the combustion in moist air giving rise to the formation of a larger proportion of fine particles than combustion in carbon dioxide under pressure. (authors) [fr

  5. Vacuum-arc chromium coatings for Zr-1%Nb alloy protection against high-temperature oxidation in air

    International Nuclear Information System (INIS)

    Kuprin, A.S.; Belous, V.A.; Bryk, V.V.; Vasilenko, R.L.; Voevodin, V.N.; Ovcharenko, V.D.; Tolmacheva, G.N.; Kolodij, I.V.; Lunev, V.M.; Klimenko, I.O.

    2015-01-01

    The effect of vacuum-arc Cr coatings on the alloy E110 resistance to the oxidation in air at temperatures 1020 and 1100 deg C for 3600 s has been investigated. The methods of scanning electron microscope, X-ray analysis and nanoindentation were used to determine the thickness, phase, mechanical properties of coatings and oxide layers. The results show that the chromium coating can effectively protect fuel tubes against high-temperature oxidation in air for one hour. In the coating during oxidation at T = 1100 deg C a Cr 2 O 3 oxide layer of 5 μm thickness is formed preventing further oxygen penetration into the coating, and thus the tube shape is conserved. Under similar test conditions the oxidation of uncoated tubes with formation of a porous monocline oxide of ZrO 2 of a thickness more than ≥ 250 μm is observed, then the deformation and cracking of samples occur and the oxide layer breaks away

  6. Full-scale testing of leakage of blast waves inside a partially vented room exposed to external air blast loading

    Science.gov (United States)

    Codina, R.; Ambrosini, D.

    2018-03-01

    For the last few decades, the effects of blast loading on structures have been studied by many researchers around the world. Explosions can be caused by events such as industrial accidents, military conflicts or terrorist attacks. Urban centers have been prone to various threats including car bombs, suicide attacks, and improvised explosive devices. Partially vented constructions subjected to external blast loading represent an important topic in protective engineering. The assessment of blast survivability inside structures and the development of design provisions with respect to internal elements require the study of the propagation and leakage of blast waves inside buildings. In this paper, full-scale tests are performed to study the effects of the leakage of blast waves inside a partially vented room that is subjected to different external blast loadings. The results obtained may be useful for proving the validity of different methods of calculation, both empirical and numerical. Moreover, the experimental results are compared with those computed using the empirical curves of the US Defense report/manual UFC 3-340. Finally, results of the dynamic response of the front masonry wall are presented in terms of accelerations and an iso-damage diagram.

  7. Pure rotational CARS thermometry studies of low-temperature oxidation kinetics in air and ethene-air nanosecond pulse discharge plasmas

    International Nuclear Information System (INIS)

    Zuzeek, Yvette; Choi, Inchul; Uddi, Mruthunjaya; Adamovich, Igor V; Lempert, Walter R

    2010-01-01

    Pure rotational CARS thermometry is used to study low-temperature plasma assisted fuel oxidation kinetics in a repetitive nanosecond pulse discharge in ethene-air at stoichiometric and fuel lean conditions at 40 Torr pressure. Air and fuel-air mixtures are excited by a burst of high-voltage nanosecond pulses (peak voltage, 20 kV; pulse duration, ∼ 25 ns) at a 40 kHz pulse repetition rate and a burst repetition rate of 10 Hz. The number of pulses in the burst is varied from a few pulses to a few hundred pulses. The results are compared with the previously developed hydrocarbon-air plasma chemistry model, modified to incorporate non-empirical scaling of the nanosecond discharge pulse energy coupled to the plasma with number density, as well as one-dimensional conduction heat transfer. Experimental time-resolved temperature, determined as a function of the number of pulses in the burst, is found to agree well with the model predictions. The results demonstrate that the heating rate in fuel-air plasmas is much faster compared with air plasmas, primarily due to energy release in exothermic reactions of fuel with O atoms generated by the plasma. It is found that the initial heating rate in fuel-air plasmas is controlled by the rate of radical (primarily O atoms) generation and is nearly independent of the equivalence ratio. At long burst durations, the heating rate in lean fuel air-mixtures is significantly reduced when all fuel is oxidized.

  8. Antioxidant and oxidative stress parameters in brain of Heteropneustes fossilis under air exposure condition; role of mitochondrial electron transport chain.

    Science.gov (United States)

    Paital, Biswaranjan

    2013-09-01

    Many fishes are exposed to air in their natural habitat or during their commercial handling. In natural habitat or during commercial handling, the cat fish Heteropneustes fossilis is exposed to air for >24h. Data on its oxidative metabolism in the above condition are not available. Oxidative stress (OS) indices (lipid and protein oxidation), toxic reactive oxygen species (ROS: H2O2) generation, antioxidative status (levels of superoxide dismutase, catalase, glutathione peroxidase and reductase, ascorbic acid and non-protein sulfhydryl) and activities of electron transport chain (ETC) enzymes (complex I-IV) were investigated in brain tissue of H. fossilis under air exposure condition (0, 3, 6, 12 and 18 h at 25°C). Decreased activities of antioxidant (except catalase) and ETC enzymes (except complex II) with increased H2O2 and OS levels were observed in the tissue under water deprivation condition. Positive correlation was observed for complex II activity and non-protein thiol groups with time period of air exposure. The critical time period to induce OS and to reduce most of the studied antioxidant level in brain was found to be 3-6h air exposure. The data can be useful to minimize the stress generated during commercial handling of the live fishes those exposed to air in general and H. fossilis in particular. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Effects of the Air Flow Rate on The Oxidation of NBG-18 and 25 Nuclear Graphite Grades

    International Nuclear Information System (INIS)

    Chi, Se-Hwan; Kim, Gen-Chan; Jang, Joon-Hee

    2007-01-01

    For a VHTR, graphite oxidation is regarded as a critical phenomenon for degrading the integrity of graphite components under normal or abnormal conditions. The oxidation of a graphite core component can occur by air which may permeate into the primary coolant operation and/or by impurities contained in the He coolant, or by air ingress during a severe accident. It is well known that the oxidation properties of a graphite are highly dependent on the source of raw materials, impurities, microstructures (crystallites, pore structure), and on the processing and environmental parameters, such as the forming methods, the coolant type, moisture and impurity content, temperature, flow rate and the oxygen potential of the coolants. A lot of work has been performed on the oxidation of graphite since the 1960s, and, for example, in the case of the temperature, a widely accepted oxidation model on the effects of a temperature has already been developed. However, in the case of the flow rate, even for its expected effects in a VHTR, for example, as to the expected changes in the bypass flow (10-20 %) during an operation, no systematic works have been performed. In this respect, as a preliminary study, the effects of an air flow rate on the oxidation of NBG-18 and 25 nuclear graphite were investigated

  10. Comparative assessment of PSI air oxidation model implementation in SCDAPSim3.5, MELCOR 1.8.6 and MELCOR 2.1

    International Nuclear Information System (INIS)

    Fernandez-Moguel, Leticia

    2015-01-01

    Highlights: • The PSI air oxidation model has been successfully implemented in MELCOR. • The model treats oxygen as an active species and nitrogen as a catalyst. • The implementation has been assessed against the previous post-test analyses for QUENCH-16. • The pre-oxidation and air phase were consistent when similar modelling options were used. • All code versions were in fair agreement with the experimental data. - Abstract: The PSI air oxidation model has been successfully implemented in the lump parameter code MELCOR. The PSI air oxidation model treats oxygen as an active species and nitrogen as a catalyst that accelerates the oxidation kinetics. The essential feature of the model is the transition from parabolic to linear kinetics. The implementation has been assessed against the previous post-test analyses for the air ingress experiment QUENCH-16 performed with a local version of RELAP5/SCDAPSim3.5. This version contains the PSI air oxidation model. The pre-oxidation and air phase were consistent when similar modelling options were used and all code versions were in fair agreement with the experimental data, showing consistency in the implementation of the model. The PSI air oxidation model will be used in the future for analysis of spent fuel pool uncovery sequences where steam/air mixture is the prototypical environment

  11. Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes

    KAUST Repository

    Da'as, E. H.; Irvine, J. T. S.; Traversa, Enrico; Boulfrad, S.

    2013-01-01

    The impregnation method has been considered as one of the most successful techniques for the fabrication of highly efficient electrodes for solid oxide fuel and electrolysis cells (SOCs) at the lab scale. However, because the impregnation is usually performed manually, its irreproducibility remains a major problem that can be solved by using controllable techniques, such as inkjet printing. In this paper, lanthanum strontium manganite (LSM)/yttria stabilized zirconia (YSZ) air electrodes were prepared by infiltrating YSZ porous bodies with LSM precursor solution using inkjet printing, followed by annealing at 800°C for 2 hours. XRD analysis confirmed the formation of the LSM phase, which was in the form of nanoparticles with size in the 50-70 nm range on the YSZ walls, as revealed by FEG-SEM observations. The effect of printing parameters on the distribution of the impregnated phase was investigated and discussed.

  12. Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes

    KAUST Repository

    Da'as, E. H.

    2013-10-07

    The impregnation method has been considered as one of the most successful techniques for the fabrication of highly efficient electrodes for solid oxide fuel and electrolysis cells (SOCs) at the lab scale. However, because the impregnation is usually performed manually, its irreproducibility remains a major problem that can be solved by using controllable techniques, such as inkjet printing. In this paper, lanthanum strontium manganite (LSM)/yttria stabilized zirconia (YSZ) air electrodes were prepared by infiltrating YSZ porous bodies with LSM precursor solution using inkjet printing, followed by annealing at 800°C for 2 hours. XRD analysis confirmed the formation of the LSM phase, which was in the form of nanoparticles with size in the 50-70 nm range on the YSZ walls, as revealed by FEG-SEM observations. The effect of printing parameters on the distribution of the impregnated phase was investigated and discussed.

  13. The effect of nitrogen oxides in air on the performance of proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Yang Daijun; Ma Jianxin; Xu Lin; Wu Minzhong; Wang Haijiang

    2006-01-01

    The effects of NO x on the performance of proton exchange membrane (PEM) fuel cell were investigated through the introduction of a mixture containing NO and NO 2 , in a ratio of 9:1, into the cathode stream of a single PEM fuel cell. The NO x concentrations used in the experiments were 1480 ppm, 140 ppm and 10 ppm, which cover a range of three orders. The experimental results obtained from the tests of durability, polarization, reversibility and electrochemical impedance spectroscopy (EIS) showed a detrimental effect of NO x on the cell performance. The electrochemical measurements results suggested that the impacts of NO x are mainly resulted from the superposition of the oxygen reduction reaction (ORR), NO and HNO 2 oxidation reactions, and the increased cathodic impedance. Complete recovery of the cell performance was reached after operating the cell with clean air and then purging with N 2 for hours

  14. Plant response to chronic exposure of low levels of oxidant type air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Feder, W.A.

    1970-01-01

    Cultivars of geranium and carnation exhibit a reduction of side branching, a retardation of floral initiation, and a decrease in floral productivity when exposed daily for 5-7 hr to 0.1 ppm ozone for 1-3 months. These plants also exhibit a reduction in leaf size, an increase in internode length, a progressive destruction of leaf tissue and eventual defoliation in the case of geranium. Cultivars of petunia exposed to chronic low levels of oxidant are slower to flower and bear fewer flowers than those same cultivars grown in charcoal-filtered air from the same source. These plant effects are of special interest because they occur in the presence of pollutant levels encountered daily in areas surrounding US metropolitan centres. 6 references, 3 figures.

  15. Secondary organic aerosol formation from in situ OH, O3, and NO3 oxidation of ambient forest air in an oxidation flow reactor

    Science.gov (United States)

    Palm, Brett B.; Campuzano-Jost, Pedro; Day, Douglas A.; Ortega, Amber M.; Fry, Juliane L.; Brown, Steven S.; Zarzana, Kyle J.; Dube, William; Wagner, Nicholas L.; Draper, Danielle C.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Gutiérrez-Montes, Cándido; Jimenez, Jose L.

    2017-04-01

    Ambient pine forest air was oxidized by OH, O3, or NO3 radicals using an oxidation flow reactor (OFR) during the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Biogenic Aerosol Study) campaign to study biogenic secondary organic aerosol (SOA) formation and organic aerosol (OA) aging. A wide range of equivalent atmospheric photochemical ages was sampled, from hours up to days (for O3 and NO3) or weeks (for OH). Ambient air processed by the OFR was typically sampled every 20-30 min, in order to determine how the availability of SOA precursor gases in ambient air changed with diurnal and synoptic conditions, for each of the three oxidants. More SOA was formed during nighttime than daytime for all three oxidants, indicating that SOA precursor concentrations were higher at night. At all times of day, OH oxidation led to approximately 4 times more SOA formation than either O3 or NO3 oxidation. This is likely because O3 and NO3 will only react with gases containing C = C bonds (e.g., terpenes) to form SOA but will not react appreciably with many of their oxidation products or any species in the gas phase that lacks a C = C bond (e.g., pinonic acid, alkanes). In contrast, OH can continue to react with compounds that lack C = C bonds to produce SOA. Closure was achieved between the amount of SOA formed from O3 and NO3 oxidation in the OFR and the SOA predicted to form from measured concentrations of ambient monoterpenes and sesquiterpenes using published chamber yields. This is in contrast to previous work at this site (Palm et al., 2016), which has shown that a source of SOA from semi- and intermediate-volatility organic compounds (S/IVOCs) 3.4 times larger than the source from measured VOCs is needed to explain the measured SOA formation from OH oxidation. This work suggests that those S/IVOCs typically do not contain C = C bonds. O3 and NO3 oxidation produced SOA with elemental O : C and H : C

  16. Continuous Photo-Oxidation in a Vortex Reactor: Efficient Operations Using Air Drawn from the Laboratory.

    Science.gov (United States)

    Lee, Darren S; Amara, Zacharias; Clark, Charlotte A; Xu, Zeyuan; Kakimpa, Bruce; Morvan, Herve P; Pickering, Stephen J; Poliakoff, Martyn; George, Michael W

    2017-07-21

    We report the construction and use of a vortex reactor which uses a rapidly rotating cylinder to generate Taylor vortices for continuous flow thermal and photochemical reactions. The reactor is designed to operate under conditions required for vortex generation. The flow pattern of the vortices has been represented using computational fluid dynamics, and the presence of the vortices can be easily visualized by observing streams of bubbles within the reactor. This approach presents certain advantages for reactions with added gases. For reactions with oxygen, the reactor offers an alternative to traditional setups as it efficiently draws in air from the lab without the need specifically to pressurize with oxygen. The rapid mixing generated by the vortices enables rapid mass transfer between the gas and the liquid phases allowing for a high efficiency dissolution of gases. The reactor has been applied to several photochemical reactions involving singlet oxygen ( 1 O 2 ) including the photo-oxidations of α-terpinene and furfuryl alcohol and the photodeborylation of phenyl boronic acid. The rotation speed of the cylinder proved to be key for reaction efficiency, and in the operation we found that the uptake of air was highest at 4000 rpm. The reactor has also been successfully applied to the synthesis of artemisinin, a potent antimalarial compound; and this three-step synthesis involving a Schenk-ene reaction with 1 O 2 , Hock cleavage with H + , and an oxidative cyclization cascade with triplet oxygen ( 3 O 2 ), from dihydroartemisinic acid was carried out as a single process in the vortex reactor.

  17. AIR POLLUTION INFLUENCES ON EXHALED NITRIC OXIDE AMONG PEOPLE WITH TYPE II DIABETES.

    Science.gov (United States)

    Peng, Cheng; Luttmann-Gibson, Heike; Zanobetti, Antonella; Cohen, Allison; De Souza, Celine; Coull, Brent A; Horton, Edward S; Schwartz, Joel; Koutrakis, Petros; Gold, Diane R

    2016-04-01

    In a population with type 2 diabetes mellitus (T2DM), we examined associations of short-term air pollutant exposures with pulmonary inflammation, measured as fraction of exhaled pulmonary nitric oxide (FeNO). Sixty-nine Boston Metropolitan residents with T2DM completed up to 5 bi-weekly visits with 321 offline FeNO measurements. We measured ambient concentrations of particle mass, number and components at our stationary central site. Ambient concentrations of gaseous air pollutants were obtained from state monitors. We used linear models with fixed effects for participants, adjusting for 24-hour mean temperature, 24-hour mean water vapor pressure, season, and scrubbed room NO the day of the visit, to estimate associations between FeNO and interquartile range increases in exposure. Interquartile increases in the 6-hour averages of black carbon (BC) (0.5 μg/m 3 ) and particle number (PN) (1,000 particles/cm 3 ) were associated with increases in FeNO of 3.84% (95% CI 0.60% to 7.18%) and 9.86 % (95% CI 3.59% to 16.52%), respectively. We also found significant associations of increases in FeNO with increases in 24-hour moving averages of BC, PN and nitrogen oxides (NOx). Recent studies have focused on FeNO as a marker for eosinophilic pulmonary inflammation in asthmatic populations. This study adds support to the relevance of FeNO as a marker for pulmonary inflammation in diabetic populations, whose underlying chronic inflammatory status is likely to be related to innate immunity and proinflammatory adipokines.

  18. Ozone and nitrogen oxides in surface air in Russia: TROICA experiments.

    Science.gov (United States)

    Pankratova, N.; Elansky, N.; Belikov, I.; Shumskiy, R.

    2009-04-01

    The results of measurements of surface ozone and nitrogen oxides concentrations over the continental regions of Russia are discussed. The measurements were done during 10 TROICA experiments (Transcontinental Observations Into the Chemistry of the Atmosphere). The TROICA experiment started in 1995. By the present moment ten expeditions along the Trans-Siberian railroad from Moscow to Vladivostok (around 9300 km) are carried out. We separate data sets into unpolluted and polluted areas to study temporal and spatial features. Moreover we analyzed cities (more then 100 cities). About 50% of all data corresponds to unpolluted conditions. The data collected are used in an analysis of the physical and chemical processes occurring over continental Russia. In this work the estimations of seasonal and daily ozone and NOx distribution were made. The seasonal distribution of ozone for TROICA experiments concentration considerably differs from ozone distribution at Mace Head (Ireland) and Hohenpeissenberg (Germany) stations and well agrees with the ozone distribution at Zotino (Russia, East Siberia). The same concerns also a daily variability. The ozone concentration gradient is presented. Ozone concentration gradually increases in the eastward direction. Its result of the air transport from polluted regions of Europe and ozone depletions, oxidations of CH4 in Siberia, forest fires in Siberia and around Baikal Lake, regional transport of burning products from Northern China. Significant factor of ozone increasing is stratospheric-tropospheric exchange. It appears in TROICA-3 experiment. During several hours ozone concentration was more then 60 ppbv. The areas of photochemical ozone generation in polluted air are also detected. We estimate anthropogenic and natural factors, which are responsible for sharp ozone concentration increasing. Acknowledgments. The work was supported by International Science and Technology Center (ISTC) under contract No. 2770 and by Russian Basic

  19. Selective oxidation with nanoporous silica supported sensitizers: An environment friendly process using air and visible light

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Cricq, Philippe; Pigot, Thierry; Blanc, Sylvie [Institut des Sciences Analytiques et de Physicochimie pour l' Environnement et les Materiaux, Universite de Pau et des Pays de l' Adour, Helioparc-2 Av. du President Angot, F-64053 Pau Cedex 09 (France); Lacombe, Sylvie, E-mail: sylvie.lacombe@univ-pau.fr [Institut des Sciences Analytiques et de Physicochimie pour l' Environnement et les Materiaux, Universite de Pau et des Pays de l' Adour, Helioparc-2 Av. du President Angot, F-64053 Pau Cedex 09 (France)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Photo-sensitizers were covalently grafted on silica matrices. Black-Right-Pointing-Pointer Grafted powdered silica was characterized by diffuse reflectance and emission spectroscopy. Black-Right-Pointing-Pointer Selective solvent-free photo-oxygenation was carried out with air under visible light. Black-Right-Pointing-Pointer Singlet generation and reactivity at the gas-solid interface was demonstrated. - Abstract: Transparent and porous silica xerogels containing various grafted photosensitizers (PSs) such as anthraquinone derivatives, Neutral Red, Acridine Yellow and a laboratory-made dicyano aromatics (DBTP) were prepared. In most cases, the xerogels were shown to be mainly microporous by porosimetry. The PSs were characterized in the powdered monoliths (form, aggregation, concentration) by electronic spectroscopy which also proved to be a useful tool for monitoring the material evolution after irradiation. These nanoporous xerogels were used as microreactors for gas/solid solvent-free photo-oxygenation of dimethylsulfide (DMS) using visible light and air as the sole reactant. All these PSs containing monoliths were efficient for gas-solid DMS oxidation, leading to sulfoxide and sulfone in varying ratios. As these polar oxidation products remained strongly adsorbed on the silica matrix, the gaseous flow at the outlet of the reactor was totally free of sulfide and odorless. The best results in term of yield and initial rate of degradation of DMS were obtained with DBTP containing xerogels. Moreover, as these materials were reusable without loss of efficiency and sensitizer photobleaching after a washing regeneration step, the concept of recyclable sensitizing materials was approved, opening the way to green process.

  20. Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

    Science.gov (United States)

    Guan, Zixuan; Chen, Di; Chueh, William C

    2017-08-30

    The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

  1. A new class of solid oxide metal-air redox batteries for advanced stationary energy storage

    Science.gov (United States)

    Zhao, Xuan

    Cost-effective and large-scale energy storage technologies are a key enabler of grid modernization. Among energy storage technologies currently being researched, developed and deployed, rechargeable batteries are unique and important that can offer a myriad of advantages over the conventional large scale siting- and geography- constrained pumped-hydro and compressed-air energy storage systems. However, current rechargeable batteries still need many breakthroughs in material optimization and system design to become commercially viable for stationary energy storage. This PhD research project investigates the energy storage characteristics of a new class of rechargeable solid oxide metal-air redox batteries (SOMARBs) that combines a regenerative solid oxide fuel cell (RSOFC) and hydrogen chemical-looping component. The RSOFC serves as the "electrical functioning unit", alternating between the fuel cell and electrolysis mode to realize discharge and charge cycles, respectively, while the hydrogen chemical-looping component functions as an energy storage unit (ESU), performing electrical-chemical energy conversion in situ via a H2/H2O-mediated metal/metal oxide redox reaction. One of the distinctive features of the new battery from conventional storage batteries is the ESU that is physically separated from the electrodes of RSOFC, allowing it to freely expand and contract without impacting the mechanical integrity of the entire battery structure. This feature also allows an easy switch in the chemistry of this battery. The materials selection for ESU is critical to energy capacity, round-trip efficiency and cost effectiveness of the new battery. Me-MeOx redox couples with favorable thermodynamics and kinetics are highly preferable. The preliminary theoretical analysis suggests that Fe-based redox couples can be a promising candidate for operating at both high and low temperatures. Therefore, the Fe-based redox-couple systems have been selected as the baseline for this

  2. Clean air. Measures against fine dust and nitrogen oxide; Luftreinhalteplanung. Massnahmen gegen Feinstaub und Stickstoffoxide

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-10-15

    Within the meeting of the Bavarian Environmental Protection Agency (Augsburg, Federal Republic of Germany) at 13th October, 2011, in Augsburg (Federal Republic of Germany), the following lectures were held: (1) Air pollution burden in Bavaria - Results from actual investigations (Juergen Diemer); (2) Winter spreading services: Reduction of particulate matter by means of CMA (Wolfgang Hafner); (3) Scenarios for the development of immission loads by NO{sub 2} at traffic-orientated air quality measuring stations in Bavaria (Frank Duennebeil); (4) Photocatalytic efficiency of titanium dioxide coatings in the reduction of the loading by nitrous oxides (Anja Baum); (5) Environmental zone Berlin (Martin Lutz); (6) Environmental zones in the Ruhr district (Cornelia Wappenschmidt); (7) Environmental zone Augsburg (Manfred Ertl); (8) Reduction of NO{sub x} by Euro 6 diesel passenger cars (Thomas Fortner); (9) (e)-Mobility leads to a new era. The next step in the evolution of the automobility (BMW Group); (10) Experience report on the FE project: 'Testing of diesel particle filters for the utilization in the inland navigation' (Torsen Mundt); (11) Reduction of the pollution burden by means of an ecological traffic control: Analysis and control of the pollution control by means of 'smart' IT solutions (Stefen Schaefer); (12) Emissions reductions at busses by means of SCRT upgrading (Detlef Plachta).

  3. Electric plants to gas, influence of both Mineral Matter and Air Oxidation in coal pyrolysis

    International Nuclear Information System (INIS)

    Mondragon, F.; Jaramillo, A.; Quintero, G.

    1995-01-01

    In this work some coal samples from different Colombia's deposits are analyzed. In first stage, material matter is removed from coal by acid treatment with HF/HCl, and aerial oxidation of coal is made with air in oven to 150 Centigrade degree temperature. In second stage, pyrolysis is carried out in two different techniques: 1. Thermogravimetric Analysis (TGA) and 2. Programmed Temperature Pyrolysis (PTP) in a pyrolyzer equipped with a quadrupole mass spectrometer. In both techniques, the coal samples are heated in different rates to 650 Centigrade degree. During PTP trials the evolution of CH4, H2S, hydrocarbons (m/z=42), CO2, benzene and toluene are monitored. Studied coal samples showed: 1). A gas conversion range between 48.8% to 21.8%; 2). A decrease in the gas conversion between 2% to 4%, when oxidation it is applied; 3). The temperature at the one which is presented the maximum evolution of CH4 is similar for all coal samples; 4). The maximum evolution of H2S depends on mineral matter composition, occurs between 480 to 550 Centigrade degrees and is presented due to pyrite decomposition. 5). The evolution of CO2 occurs between 100 to 650 Centigrade degree, its production is generated in different stage of the mentioned temperature range, and in some coal samples is presented due to inorganic origin

  4. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    Science.gov (United States)

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension. Copyright © 2015, American Association for the Advancement of Science.

  5. [Anesthesia with isoflurane in air and with isoflurane and nitrous oxide].

    Science.gov (United States)

    Girardi, G; Rossi, R; Cellai, M P; Pieraccioli, E; Novelli, G P

    1994-06-01

    The aim of this study is to control the depth, the quality of recovery of total inhalation isoflurane anesthesia with or without nitrous oxide. Controlled comparative study was carried out on 51 patients, aged 40-54 yr, ASA 1, undergoing saphenectomy, in an University Clinic. Induction: thiopental (3.5 mg kg), atracurium (0.6 mg kg) i.v. Patients were randomly assigned to: group 1 (26 patients), 5% isoflurane in air, by mask; group 2 (25 patients), 3% isoflurane and 60% N2O, by mask. Maintenance: group 1, 2% isoflurane in air; group 2, 1.2% isoflurane and 60% N2O. During anesthesia, consciousness and analgesia level were monitored by EEG Compressed Spectral Array, and clinical signs of pain by Evans' test; arousal time evaluation by "Time to correct response test". The subjective impressions, eventual dreams and recalls were collected using a standard set of questions one hour after the end of anesthesia and 24 hours later. One hour before anesthesia and two hours after the end of surgical procedures, a psychomotor performance recovery evaluation was performed using Zazzo's "deux barrages" test. Student's "t" test. Adequate anesthetic depth was documented in all patients. Recovery time was statistically longer in isoflurane group (group 1 16.7 sd 2.2 minutes vs 10.3 sd 1.9 minutes group 2, p hours after recovery no significant differences in psychomotor performance tests were recorded. Isoflurane anesthesia in air, in adequate concentrations, provides a sufficient level of analgesia, hypnosis, amnesia, without clinical side effects.

  6. Oxidation of UO2 at 400 to 1000 degrees C in air and its relevance to fission product release

    International Nuclear Information System (INIS)

    McCracken, D.R.

    1985-07-01

    Currently there is great interest in the behaviour of UO 2 under oxidizing conditions because irradiated uranium dioxide fuel can conceivably be exposed to a hot oxidizing atmosphere as a result of accidents. The temperature range covered in this paper is 400 to 1000 degrees C. At these high temperatures, UO 2 in air can oxidize rapidly to U 3 O 8 via U 3 O 7 and/or U 4 O 9 . The accompanying volume increase and corresponding stresses lead to fragmentation of the fuel pellets. The purpose of this work was to investigate the dependence of UO 2 oxidation on temperature, rate of air supply and residence time at temperature; to determine the rate controlling steps and rate of oxygen penetration; and to characterize the oxidation products and size of fragments. In addition, detailed metallography was related to X-ray diffraction studies of the oxidized UO 2 to facilitate future study of irradiated fuel, which is easier to do by metallography in hot-cells than by X-ray diffraction. Samples were heated in argon, then once at temperature they were exposed to air at a controlled flow-rate. Studies of the oxidation of unirradiated UO 2 pellets in air show two distinct types of oxidation with a change in mechanism at 600-700 degrees C. At temperatures ≤ 600 degrees C fragmentation accompanies the formation of U 3 O 8 while at T ≥ 800 degrees C, rapid grain growth occurs. In the first temperature region, volatile fission product releases are small, while in the second region, 100% release can be correlated with U 3 O 8 formation. In the first region, only the grain boundary inventory is released while in the other, 100% of the Xe, Kr, Ru, Sb, Cs and I are released. It appears that, within the error of present measurements, burnup does not affect rates of fission product release and oxidation in air at 400 to 1000 degrees C, so that oxidation rate data gathered using unirradiated pellets can be applied to irradiated fuel. 33 refs

  7. Long Term Stability Investigation of Solid Oxide Electrolysis Cell with Infiltrated Porous YSZ Air Electrode Under High Current

    DEFF Research Database (Denmark)

    Veltzé, Sune; Ovtar, Simona; Simonsen, Søren Bredmose

    2015-01-01

    stabilised zirconia (YSZ) backbone air electrode and Ni/YSZ cermet fuel electrode. The SOC was tested at electrolysis conditions under high current (up to -1 A/cm2). The porous YSZ electrodes was infiltrated with gadolinium-doped ceria oxide (CGO), to act as a barrier layer between the catalyst...

  8. 77 FR 63827 - Request for Nominations of Experts for the Clean Air Scientific Advisory Committee (CASAC) Oxides...

    Science.gov (United States)

    2012-10-17

    ... health-based) air quality standards for oxides of nitrogen (NO X ). DATES: Nominations should be..., medicine, public health, biostatistics and risk assessment. Process and Deadline for Submitting Nominations... later than November 7, 2012. EPA values and welcomes diversity. In an effort to obtain nominations of...

  9. Oxidative damage to biological macromolecules in Prague bus drivers and garagemen: Impact of air pollution and genetic polymorphisms

    Czech Academy of Sciences Publication Activity Database

    Bagryantseva, Yana; Novotná, Božena; Rössner ml., Pavel; Chvátalová, Irena; Milcová, Alena; Švecová, Vlasta; Lněničková, Zdena; Solanský, I.; Šrám, Radim

    2010-01-01

    Roč. 199, č. 1 (2010), s. 60-68 ISSN 0378-4274 R&D Projects: GA MŽP(CZ) SP/1B3/8/08 Institutional research plan: CEZ:AV0Z50390512 Keywords : air pollution * bud drivers * oxidative stress Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 3.581, year: 2010

  10. Impact of Air Oxidation on Dissolved Organic Matter from Boom Clay: Comparison Between Natural and Artificial Oxidation Series and In Situ Piezometers Water From Hades Galleries

    International Nuclear Information System (INIS)

    Blanchart, Pascale; Faure, Pierre; Michels, Raymond; Bruggeman, Christophe; De Craen, Mieke; Parant, Stephane

    2012-01-01

    Document available in extended abstract form only. The Boom Clay is considered by the Belgian radioactive waste management agency Ondraf/Niras as a possible host rock for the geological disposal of high-level and long-lived radioactive waste. The drilling of galleries and corings in the Boom Clay (Mol, Belgium) leads to perturbations of the initial physical and chemical conditions. In piezometers, the DOC may show considerable and irregular variations through time, with values ranging from 80 to 425 mg/L. The origin and bio-physico-chemical controls of such variations are yet unknown but oxidation and biodegradation were considered as most likely. Three categories of samples were collected with the aim of determining and quantifying different molecular markers representative for the oxidation process: - Fresh as well as air-oxidized Boom Clay samples were collected in the Underground Research Facility HADES of EURIDICE (Mol, Belgium): they represent a natural series of oxidation; - A fresh Boom Clay sample was submitted to laboratory air oxidation (artificial series). In these experiments, powdered clay was heated at 80 deg. C under air flow during 1, 3, 6, 9, 12, 18 months; - Four water samples were collected during January 2010 from different horizons in the Boom Clay by means of piezometers located in the Underground Research Facility. The DOM (dissolved organic matter) of Boom Clay samples (artificial and natural series) was isolated by Soxhlet using pure water as well as by leaching experiments. The quantitative analysis shows an increasing in DOC (Dissolved Organic Carbon) content with oxidation. Qualitative characterizations including spectroscopic (3D-fluorescence) as well as molecular analyses (flash pyrolysis - gas chromatography - mass spectrometry (PyGC-MS) and size exclusion chromatography (SEC-HPLC)) show an evolution of the DOM chemistry with oxidation: - An enrichment in oxygen bearing molecules (acidic poly functional groups); - A decrease in

  11. Storage of LWR spent fuel in air: Volume 1: Design and operation of a spent fuel oxidation test facility

    International Nuclear Information System (INIS)

    Thornhill, C.K.; Campbell, T.K.; Thornhill, R.E.

    1988-12-01

    This report describes the design and operation and technical accomplishments of a spent-fuel oxidation test facility at the Pacific Northwest Laboratory. The objective of the experiments conducted in this facility was to develop a data base for determining spent-fuel dry storage temperature limits by characterizing the oxidation behavior of light-water reactor (LWR) spent fuels in air. These data are needed to support licensing of dry storage in air as an alternative to spent-fuel storage in water pools. They are to be used to develop and validate predictive models of spent-fuel behavior during dry air storage in an Independent Spent Fuel Storage Installation (ISFSI). The present licensed alternative to pool storage of spent fuel is dry storage in an inert gas environment, which is called inerted dry storage (IDS). Licensed air storage, however, would not require monitoring for maintenance of an inert-gas environment (which IDS requires) but does require the development of allowable temperature limits below which UO 2 oxidation in breached fuel rods would not become a problem. Scoping tests at PNL with nonirradiated UO 2 pellets and spent-fuel fragment specimens identified the need for a statistically designed test matrix with test temperatures bounding anticipated maximum acceptable air-storage temperatures. This facility was designed and operated to satisfy that need. 7 refs

  12. Development and Application of an Oxidation Flow Reactor to Study Secondary Organic Aerosol Formation from Ambient Air

    Science.gov (United States)

    Palm, Brett Brian

    Secondary organic aerosols (SOA) in the atmosphere play an important role in air quality, human health, and climate. However, the sources, formation pathways, and fate of SOA are poorly constrained. In this dissertation, I present development and application of the oxidation flow reactor (OFR) technique for studying SOA formation from OH, O3, and NO3 oxidation of ambient air. With a several-minute residence time and a portable design with no inlet, OFRs are particularly well-suited for this purpose. I first introduce the OFR concept, and discuss several advances I have made in performing and interpreting OFR experiments. This includes estimating oxidant exposures, modeling the fate of low-volatility gases in the OFR (wall loss, condensation, and oxidation), and comparing SOA yields of single precursors in the OFR with yields measured in environmental chambers. When these experimental details are carefully considered, SOA formation in an OFR can be more reliably compared with ambient SOA formation processes. I then present an overview of what OFR measurements have taught us about SOA formation in the atmosphere. I provide a comparison of SOA formation from OH, O3, and NO3 oxidation of ambient air in a wide variety of environments, from rural forests to urban air. In a rural forest, the SOA formation correlated with biogenic precursors (e.g., monoterpenes). In urban air, it correlated instead with reactive anthropogenic tracers (e.g., trimethylbenzene). In mixed-source regions, the SOA formation did not correlate well with any single precursor, but could be predicted by multilinear regression from several precursors. Despite these correlations, the concentrations of speciated ambient VOCs could only explain approximately 10-50% of the total SOA formed from OH oxidation. In contrast, ambient VOCs could explain all of the SOA formation observed from O3 and NO3 oxidation. Evidence suggests that lower-volatility gases (semivolatile and intermediate-volatility organic

  13. The Relationship Between Structural and Catalytic Activity of α and γ-Bismuth-Molybdate Catalysts for Partial Oxidation of Propylene to Acrolein

    Science.gov (United States)

    Fansuri, H.; Pham, G. H.; Wibawanta, S.; Zhang, D. K.; French, David

    Bismuth-molybdate catalysts are known to be effective for catalytic partial oxidation of propylene to acrolein. Their properties and the kinetics and reaction mechanisms for acrolein production have been extensively studied, especially in their basic forms, such as α, β, and γ-bismuth-molybdate. Although the reaction mechanisms have been reported widely in the literature, a general agreement has not been reached, especially from a catalyst-structure point of view. The present contribution reports an effort to understand the structural changes of α and γ-bismuth-molybdate catalysts at varying temperatures as examined using high temperature XRD and to relate the catalyst performance (activity and selectivity) for propylene partial oxidation to acrolein. The XRD analysis was performed at temperature between 250 and 450°C in ambient atmosphere and the Rietveld refinement method was used to extract unit cell parameters. The results showed a distinct similarity between the shapes of the thermal expansion of the catalysts and their activity and selectivity curves, indicating a significant role that the catalyst interatomic structure plays in the overall reaction mechanism.

  14. Low-temperature, mineral-catalyzed air oxidation: a possible new pathway for PAH stabilization in sediments and soils.

    Science.gov (United States)

    Ghislain, Thierry; Faure, Pierre; Biache, Coralie; Michels, Raymond

    2010-11-15

    Reactivity of polycyclic aromatic hydrocarbons (PAHs) in the subsurface is of importance to environmental assessment, as they constitute a highly toxic hazard. Understanding their reactivity in the long term in natural recovering systems is thus a key issue. This article describes an experimental investigation on the air oxidation of fluoranthene (a PAH abundant in natural systems polluted by industrial coal use) at 100°C on different mineral substrates commonly found in soils and sediments (quartz sand, limestone, and clay). Results demonstrate that fluoranthene is readily oxidized in the presence of limestone and clay, leading to the formation of high molecular weight compounds and a carbonaceous residue as end product especially for clay experiments. As demonstrated elsewhere, the experimental conditions used permitted the reproduction of the geochemical pathway of organic matter observed under natural conditions. It is therefore suggested that low-temperature, mineral-catalyzed air oxidation is a mechanism relevant to the stabilization of PAHs in sediments and soils.

  15. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2002-01-01

    The influence of environmental factors on the community structure of ammonia-oxidizing bacteria (AOB) was investigated in the Schelde estuary. Simultaneously with the increase of oxygen and salinity, a shift of the dominant AOB was observed. Molecular analysis based on 16S rRNA genes showed that the

  16. Air pollution: what matters most? : Physical, chemical and oxidative properties of air pollution components related to toxic effects

    NARCIS (Netherlands)

    Steenhof, M.

    2015-01-01

    Numerous studies have been published on the adverse health effects associated with both short- and long-term exposure to air pollution. Air pollution is a heterogeneous, complex mixture of gases, liquids, and particulate matter (PM). Up to now, PM mass concentration has been the metric of choice to

  17. Oxidation Behavior of Mo-Si-B Alloys in Wet Air; TOPICAL

    International Nuclear Information System (INIS)

    M. Kramer; A. Thom; O. Degirmen; V. Behrani; M. Akinc

    2002-01-01

    Multiphase composite alloys based on the Mo-Si-B system are candidate materials for ultra-high temperature applications. In non load-bearing uses such as thermal barrier coatings or heat exchangers in fossil fuel burners, these materials may be ideally suited. The present work investigated the effect of water vapor on the oxidation behavior of Mo-Si-B phase assemblages. Three alloys were studied: Alloy 1= Mo(sub 5)Si(sub 3)B(sub x) (T1)- MoSi(sub 2)- MoB, Alloy 2= T1- Mo(sub 5)SiB(sub 2) (T2)- Mo(sub 3)Si, and Alloy 3= Mo- T2- Mo(sub 3)Si. Tests were conducted at 1000 and 1100C in controlled atmospheres of dry air and wet air nominally containing 18, 55, and 150 Torr H(sub 2)O. The initial mass loss of each alloy was approximately independent of the test temperature and moisture content of the atmosphere. The magnitude of these initial losses varied according to the Mo content of the alloys. All alloys formed a continuous, external silica scale that protected against further mass change after volatilization of the initially formed MoO(sub 3). All alloys experienced a small steady state mass change, but the calculated rates cannot be quantitatively compared due to statistical uncertainty in the individual mass measurements. Of particular interest is that Alloy 3, which contains a significant volume fraction of Mo metal, formed a protective scale. All alloys formed varying amounts of subscale Mo and MoO(sub 2). This implies that oxygen transport through the external silica scale has been significantly reduced. For all alloys, water vapor accelerated the growth of a multiphase interlayer at the silica scale/unoxidized alloy interface. This interlayer is likely composed of fine Mo and MoO(sub 2) that is dispersed within a thin silica matrix. Alloy 3 was particularly sensitive to water accelerated growth of this interlayer. At 1100 C, the scale thickness after 300 hours increased from about 20 mm in dry air to nearly 100 mm in wet air

  18. Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

    Science.gov (United States)

    Krisnandi, Y. K.; Yanti, F. M.; Murti, S. D. S.

    2017-04-01

    Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO4 4-) and aluminate (AlO4 5-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (v asymetric T-O), 820-650 cm-1 (v symetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

  19. Influence of Ti Content on the Partial Oxidation of TixFeCoNi Thin Films in Vacuum Annealing

    Directory of Open Access Journals (Sweden)

    Ya-Chu Yang

    2017-09-01

    Full Text Available This study investigated the effects of Ti content and vacuum annealing on the microstructure evolution of TixFeCoNi (x = 0, 0.5, and 1 thin films and the underlying mechanisms. The as-deposited thin film transformed from an FCC (face center cubic structure at x = 0 into an amorphous structure at x = 1, which can be explained by determining topological instability and a hard ball model. After annealing was performed at 1000 °C for 30 min, the films presented a layered structure comprising metal solid solutions and oxygen-deficient oxides, which can be major attributed to oxygen traces in the vacuum furnace. Different Ti contents provided various phase separation and layered structures. The underlying mechanism is mainly related to the competition among possible oxides in terms of free energy production at 1000 °C.

  20. Comparison of the air oxidation behaviors of Zircaloy-4 implanted with yttrium and cerium ions at 500 deg. C

    International Nuclear Information System (INIS)

    Chen, X.W.; Bai, X.D.; Xu, J.; Zhou, Q.G.; Chen, B.S.

    2002-01-01

    As a valuable process for surface modification of materials, ion implantation is eminent to improve mechanical properties, electrochemical corrosion resistance and oxidation behaviors of varieties of materials. To investigate and compare the oxidation behaviors of Zircaloy-4, implantation of yttrium ion and cerium ion were respectively employed by using an MEVVA source at the energy of 40 keV with a dose ranging from 1x10 16 to 1x10 17 ions/cm 2 . Subsequently, weight gain curves of the different specimens including as-received Zircaloy-4 and Zircaloy-4 specimens implanted with the different ions were measured after oxidation in air at 500 deg. C for 100 min. It was obviously found that a significant improvement was achieved in the oxidation behaviors of implanted Zircaloy-4 compared with that of the as-received Zircaloy-4, and the oxidation behavior of cerium-implanted Zircaloy-4 was somewhat better than that of yttrium-implanted specimen. To obtain the valence and the composition of the oxides in the scale, X-ray photoemission spectroscopy was used in the present study. Glancing angle X-ray diffraction, employed to analyze the phase transformation in the oxide films, showed that the addition of yttrium transformed the phase from monoclinic zirconia to tetragonal zirconia, yet the addition of cerium transformed the phase from monoclinic zirconia to hexagonal zirconia. In the end, the mechanism of the improvement of the oxidation behavior was discussed

  1. Performance of ultraviolet photocatalytic oxidation for indoor air applications: Systematic experimental evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Lexuan [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Haghighat, Fariborz, E-mail: fariborz.haghighat@concordia.ca [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lee, Chang-Seo [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lakdawala, Ness [DECTRON International Inc., Montreal, Quebec (Canada)

    2013-10-15

    Highlights: • An innovative experimental set-up was designed and constructed for testing UV-PCO. • Test methodologies were developed to examine UV-PCO air cleaners for VOCs removal. • VOCs type, inlet concentration, flow rate, irradiance, and RH have influence on PCO. • Gas-phase ozonation with a variety of compounds was examined in a duct system. • Formation of by-products generated from incomplete conversion was investigated. -- Abstract: Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology.

  2. Performance of ultraviolet photocatalytic oxidation for indoor air applications: Systematic experimental evaluation

    International Nuclear Information System (INIS)

    Zhong, Lexuan; Haghighat, Fariborz; Lee, Chang-Seo; Lakdawala, Ness

    2013-01-01

    Highlights: • An innovative experimental set-up was designed and constructed for testing UV-PCO. • Test methodologies were developed to examine UV-PCO air cleaners for VOCs removal. • VOCs type, inlet concentration, flow rate, irradiance, and RH have influence on PCO. • Gas-phase ozonation with a variety of compounds was examined in a duct system. • Formation of by-products generated from incomplete conversion was investigated. -- Abstract: Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology

  3. Microwave-Assisted Coprecipitation Synthesis of LaCoO3 Nanoparticles and Their Catalytic Activity for Syngas Production by Partial Oxidation of Methane

    Directory of Open Access Journals (Sweden)

    Consuelo Alvarez-Galvan

    2018-04-01

    Full Text Available LaCoO3 perovskite-type oxides were prepared by microwave-assisted coprecipitation route and investigated in the catalytic partial oxidation of methane (CPOM to syngas. This preparation method aims to achieve higher specific surface areas (ssa than soft-chemical methods commonly used in the preparation of engineered materials. In an attempt to accomplish the creation of mesostructured porous LaCoO3, an ionic template such as cetyl trimethyl ammonium bromide has been used as endotemplate in some samples. The influence of pH and the type of precipitating agent has been studied. The materials have been characterized at different levels: morphology has been studied by scanning electron microscopy, textural properties by nitrogen adsorption–desorption at −196°C, structural analysis by X-ray diffraction, surface composition by X-ray photoelectron spectroscopy, thermal stability by thermogravimetric analysis, and carbon formation in spent catalysts by Raman spectroscopy. Structure-activity correlations point out that the precipitating agent has a key role on the morphology and porosity of the resultant oxide, as well as on the average crystalline domain of lanthanum perovskite (catalyst precursor. Thus, the use of ammonium hydroxide as precipitant leads to materials with a higher surface area and a greater ssa of cobalt (per unit mass, improving their catalytic performance for the CPOM reaction. The best catalytic performance was found for the catalyst prepared using ammonium hydroxide as precipitant (pH 9 and without adding CTAB as endotemplate.

  4. Ni/SiO2 Catalyst Prepared with Nickel Nitrate Precursor for Combination of CO2 Reforming and Partial Oxidation of Methane: Characterization and Deactivation Mechanism Investigation

    Directory of Open Access Journals (Sweden)

    Sufang He

    2015-01-01

    Full Text Available The performance of Ni/SiO2 catalyst in the process of combination of CO2 reforming and partial oxidation of methane to produce syngas was studied. The Ni/SiO2 catalysts were prepared by using incipient wetness impregnation method with nickel nitrate as a precursor and characterized by FT-IR, TG-DTA, UV-Raman, XRD, TEM, and H2-TPR. The metal nickel particles with the average size of 37.5 nm were highly dispersed over the catalyst, while the interaction between nickel particles and SiO2 support is relatively weak. The weak NiO-SiO2 interaction disappeared after repeating oxidation-reduction-oxidation in the fluidized bed reactor at 700°C, which resulted in the sintering of metal nickel particles. As a result, a rapid deactivation of the Ni/SiO2 catalysts was observed in 2.5 h reaction on stream.

  5. Effects of Post-Pyrolysis Air Oxidation of Biomass Chars on Adsorption of Neutral and Ionizable Compounds.

    Science.gov (United States)

    Xiao, Feng; Pignatello, Joseph J

    2016-06-21

    This study was conducted to understand the effects of thermal air oxidation of biomass chars experienced during formation or production on their adsorptive properties toward various compounds, including five neutral nonpolar and polar compounds and seven weak acids and bases (pKa = 3-5.2) selected from among industrial chemicals and the triazine and phenoxyacetic acid herbicide classes. Post-pyrolysis air oxidation (PPAO) at 400 °C of anoxically prepared wood and pecan shell chars for up to 40 min enhanced the mass-normalized adsorption at pH ∼ 7.4 of all test compounds, especially the weak acids and bases, by up to 100-fold. Both general and specific effects were identified. The general effect results from "reaming" of pores by the oxidative removal of pore wall matter and/or tarry deposits generated during the pyrolysis step. Reaming creates new surface area and enlarges nanopores, which helps relieve steric hindrance to adsorption. The specific effect results from creation of new acidic functionality that provides sites for the formation of very strong, charge-assisted hydrogen bonds (CAHB) with solutes having comparable pKa. The CAHB hypothesis was supported by competition experiments and the finding that weak acid anion adsorption increased with surface carboxyl content, despite electrostatic repulsion from the growing negative charge. The results provide insight into the effects of air oxidation on pollutant retention.

  6. Enhancement of corrosion resistance for plasma nitrided AISI 4140 steel by plain air plasma post-oxidizing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiqiang; Liu, Han; Ye, Xuemei [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Chai, Yating [Materials Research and Education Center, Auburn University, AL 36849 (United States); Hu, Jing, E-mail: jinghoo@126.com [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Materials Research and Education Center, Auburn University, AL 36849 (United States)

    2015-05-25

    Highlights: • Plain air was primarily used for plasma post-oxidation for AISI 4140 steel. • A thin iron oxide layer composed of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was formed on top of the compound layer. • The ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was closely related to the post-oxidizing conditions. • Post-oxidizing at 673 K for 60 min brought out highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} and optimum corrosion resistance. - Abstract: Plasma post-oxidizing was conducted immediately after plasma nitriding in the same equipment for AISI 4140 steel, and plain air was used as the oxygen bearing gas. The cross-sectional microstructures of the treated samples were observed by optical metallography and scanning electron microcopy (SEM), and the thickness of compound layer was measured accordingly. The phases were determined by X-ray diffraction (XRD), corrosion resistance was evaluated by electrochemical polarization, and the surface morphology before and after polarization test was also observed by SEM. Meanwhile, standard Gibbs free energy of the oxidation reactions existed in Fe–O system was calculated. The results show that a thin iron oxide layer composed of magnetite (Fe{sub 3}O{sub 4}) and hematite (Fe{sub 2}O{sub 3}) is formed on top of the compound layer during plasma post-oxidizing process, and the ratio of magnetite (Fe{sub 3}O{sub 4}) to hematite (Fe{sub 2}O{sub 3}) is depended on plasma post-oxidizing temperature and time. Highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} is obtained while post-oxidizing at 673 K for 60 min due to lower standard Gibbs free energy and appropriate forming rate for the formation of Fe{sub 3}O{sub 4} at this temperature. The thin oxide layer brings out significant enhancement of corrosion resistance, especially at higher ratios of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3}, due to the dense and adherent characteristic of Fe{sub 3}O{sub 4} oxide. Surface images of the post-oxidizing specimen

  7. Oxidation kinetics of innovative carbon materials with respect to severe air ingress accidents in HTRs and graphite disposal or processing

    International Nuclear Information System (INIS)

    Schloegel, Baerbel

    2010-01-01

    Currently future nuclear reactor concepts of the Fourth Generation (Gen IV) are under development. To some extend they apply with new, innovative materials developed just for this purpose. This thesis work aims at a concept of Generation IV Very High Temperature Reactors (VHTR) in the framework of the European project RAPHAEL (ReActor for Process heat, Hydrogen And ELectricity generation). The concept named ANTARES (AREVA New Technology based on advanced gas-cooled Reactors for Energy Supply) was developed by AEVA NP. It is a helium cooled, graphite moderated modular reactor for electricity and hydrogen production, by providing the necessary process heat due to its high working temperature. Particular attention is given here to oxidation kinetics of newly developed carbon materials (NBG-17) with still unknown but needed information in context of severe air ingress accident in VHTR's. Special interest is paid to the Boudouard reaction, the oxidation of carbon by CO 2 . In case of an air ingress accident, carbon dioxide is produced in the primary reaction of atmospheric oxygen with reflector graphite. From there CO 2 could flow into the reactor core causing further damage by conversion into CO. The purpose of this thesis is to ascertain if and to what degree this could happen. First of all oxidation kinetic data of the Boudouard reaction with NBG-17 is determined by experiments in a thermo gravimetric facility. The measurements are evaluated and converted into a common formula and a Langmuir-Hinshelwood similar oxidation kinetic equation, as input for the computer code REACT/THERMIX. This code is then applied to analyse severe air ingress accidents for several air flow rates. The results are discussed for two accident situations, in which a certain graphite burn off is achieved. All cases show much more damage to the graphite bottom reflector than to the reactor core. Thus the bottom reflector will lose its structural integrity much earlier than the core itself will

  8. Anchoring Tri(8-QuinolinolatoIron Onto Sba-15 for Partial Oxidation of Benzyl Alcohol Using Water as the Solvent

    Directory of Open Access Journals (Sweden)

    Yang Xiaoyuan

    2014-09-01

    Full Text Available Tri(8-quinolinolatoiron complex immobilized onto SBA-15 catalyst has been synthesized through a stepwise procedure. The characterization results indicated that the BET surface area, total pore volume and average pore width decrease after stepwise modification of SBA-15, while the structure keeps intact. Catalytic tests showed that FeQ3-SBA-15 catalyzes the oxidation reaction well with 34.8% conversion of benzyl alcohol and 74.7% selectivity to benzaldehyde when water is used as the solvent after 1 h reaction. In addition, homogeneous catalyst tri(8-quinolinolatoiron exhibits very bad catalytic behavior using water as the solvent.

  9. FY-09 Report: Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Chang H. Oh; Eung S. Kim

    2009-12-01

    The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in the Next Generation Nuclear Plant (NGNP)/Gen-IV very high temperature reactor (VHTR). Phenomena Identification and Ranking Studies to date have identified that an air ingress event following on the heels of a VHTR depressurization is a very important incident. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority for the NGNP Project. Following a loss of coolant and system depressurization incident, air will enter the core through the break, leading to oxidation of the in-core graphite structure and fuel. If this accident occurs, the oxidation will accelerate heat-up of the bottom reflector and the reactor core and will eventually cause the release of fission products. The potential collapse of the core bottom structures causing the release of CO and fission products is one of the concerns. Therefore, experimental validation with the analytical model and computational fluid dynamic (CFD) model developed in this study is very important. Estimating the proper safety margin will require experimental data and tools, including accurate multidimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model. It will also require effective strategies to mitigate the effects of oxidation. The results from this research will provide crucial inputs to the INL NGNP/VHTR Methods Research and Development project. The second year of this three-year project (FY-08 to FY-10) was focused on (a) the analytical, CFD, and experimental study of air ingress caused by density-driven, stratified, countercurrent flow; (b) advanced graphite oxidation experiments and modeling; (c) experimental study of burn-off in the core bottom structures, (d) implementation of advanced

  10. First-principles calculation on electronic properties of zinc oxide by zinc–air system

    Directory of Open Access Journals (Sweden)

    Ahmad Azmin Mohamad

    2017-07-01

    Full Text Available First-principles calculations are performed to study the electronic properties of zinc oxide (ZnO formed on an anode after discharging a Zn–air system. Prior to calculation, the ZnO is characterised by X-ray diffraction using Rietveld refinement. Diffracted patterns proved the formation of single phase ZnO, while Rietveld analysis shows that the ZnO has a hexagonal wurtzite structure with lattice parameters, a = 3.244 and c = 5.199 Å. Geometry optimisation of the hexagonal wurtzite structure of the ZnO is performed using various exchange–correlation energy functionals. The local density approximation functional method is used to explain the structure, electronic band structure and density of state properties of hexagonal ZnO. The calculated energy band gap was 0.75 eV while the density of states reveals that the O 2p (the top valence band and Zn 4s (the bottom conduction band states domination.

  11. Surface structure-dependent pyrite oxidation in relatively dry and moist air: Implications for the reaction mechanism and sulfur evolution

    Science.gov (United States)

    Zhu, Jianxi; Xian, Haiyang; Lin, Xiaoju; Tang, Hongmei; Du, Runxiang; Yang, Yiping; Zhu, Runliang; Liang, Xiaoliang; Wei, Jingming; Teng, H. Henry; He, Hongping

    2018-05-01

    Pyrite oxidation not only is environmentally significant in the formation of acid mine (or acid rock) drainage and oxidative acidification of lacustrine sediment but also is a critical stage in geochemical sulfur evolution. The oxidation process is always controlled by the reactivity of pyrite, which in turn is controlled by its surface structure. In this study, the oxidation behavior of naturally existing {1 0 0}, {1 1 1}, and {2 1 0} facets of pyrite was investigated using a comprehensive approach combining X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, and time-of-flight secondary-ion mass spectrometry with periodic density functional theoretical (DFT) calculations. The experimental results show that (i) the initial oxidation rates of both pyrite {1 1 1} and {2 1 0} are much greater than that of pyrite {1 0 0}; (ii) the initial oxidation rate of pyrite {2 1 0} is greater than that of pyrite {1 1 1} in low relative humidity, which is reversed in high relative humidity; and (iii) inner sphere oxygen-bearing sulfur species are originally generated from surface reactions and then converted to outer sphere species. The facet dependent rate law can be expressed as: r{hkl} =k{hkl}haP0.5(t + 1) - 0.5 , where r{hkl} is the orientation dependent reaction rate, k{hkl} is the orientation dependent rate constant, h is the relative humidity, P is the oxygen partial pressure, and t is the oxidation time in seconds. {1 1 1} is the most sensitive facet for pyrite oxidation. Combined with DFT theoretical investigations, water catalyzed electron transfer is speculated as the rate-limiting step. These findings disclose the structure-reactivity dependence of pyrite, which not only presents new insight into the mechanism of pyrite oxidation but also provides fundamental data to evaluate sulfur speciation evolution, suggesting that the surface structure sensitivity should be considered to estimate the reactivity at the mineral

  12. Rf-sputtered vanadium oxide thin films: effect of oxygen partial pressure on structural and electrochemical properties

    CERN Document Server

    Park, Y J; Ryu, K S; Chang, S H; Park, S C; Yoon, S M; Kim, D K

    2001-01-01

    Vanadium oxide thin films with thickness of about 2000 A have been prepared by radio frequency sputter deposition using a V sub 2 O sub 5 target in a mixed argon and oxygen atmosphere with different Ar/O sub 2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V sub O sub 5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O sub 2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V sub O sub 5 film deposited at the Ar/O sub 2 ratio of 90/10 exhibits high discharge capacity of 100 mu Ah/cm sup 2 -mu m along with good cycle performance.

  13. The impact of partial manganese superoxide dismutase (SOD2)-deficiency on mitochondrial oxidant stress, DNA fragmentation and liver injury during acetaminophen hepatotoxicity

    International Nuclear Information System (INIS)

    Ramachandran, Anup; Lebofsky, Margitta; Weinman, Steven A.; Jaeschke, Hartmut

    2011-01-01

    Acetaminophen (APAP) hepatotoxicity is the most frequent cause of acute liver failure in many countries. The mechanism of cell death is initiated by formation of a reactive metabolite that binds to mitochondrial proteins and promotes mitochondrial dysfunction and oxidant stress. Manganese superoxide dismutase (SOD2) is a critical defense enzyme located in the mitochondrial matrix. The objective of this investigation was to evaluate the functional consequences of partial SOD2-deficiency (SOD2+/-) on intracellular signaling mechanisms of necrotic cell death after APAP overdose. Treatment of C57Bl/6J wild type animals with 200 mg/kg APAP resulted in liver injury as indicated by elevated plasma alanine aminotransferase activities (2870 ± 180 U/L) and centrilobular necrosis at 6 h. In addition, increased tissue glutathione disulfide (GSSG) levels and GSSG-to-GSH ratios, delayed mitochondrial GSH recovery, and increased mitochondrial protein carbonyls and nitrotyrosine protein adducts indicated mitochondrial oxidant stress. In addition, nuclear DNA fragmentation (TUNEL assay) correlated with translocation of Bax to the mitochondria and release of apoptosis-inducing factor (AIF). Furthermore, activation of c-jun-N-terminal kinase (JNK) was documented by the mitochondrial translocation of phospho-JNK. SOD2+/- mice showed 4-fold higher ALT activities and necrosis, an enhancement of all parameters of the mitochondrial oxidant stress, more AIF release and more extensive DNA fragmentation and more prolonged JNK activation. Conclusions: the impaired defense against mitochondrial superoxide formation in SOD2+/- mice prolongs JNK activation after APAP overdose and consequently further enhances the mitochondrial oxidant stress leading to exaggerated mitochondrial dysfunction, release of intermembrane proteins with nuclear DNA fragmentation and more necrosis.

  14. Structural evidence for the partially oxidized dipyrromethene and dipyrromethanone forms of the cofactor of porphobilinogen deaminase: structures of the Bacillus megaterium enzyme at near-atomic resolution

    International Nuclear Information System (INIS)

    Azim, N.; Deery, E.; Warren, M. J.; Wolfenden, B. A. A.; Erskine, P.; Cooper, J. B.; Coker, A.; Wood, S. P.; Akhtar, M.

    2014-01-01

    The enzyme porphobilinogen deaminase (PBGD; hydroxymethylbilane synthase; EC 2.5.1.61) catalyses a key early step in the biosynthesis of tetrapyrroles in which four molecules of the monopyrrole porphobilinogen are condensed to form a linear tetrapyrrole. Two near-atomic resolution structures of PBGD from B. megaterium are reported that demonstrate the time-dependent accumulation of partially oxidized forms of the cofactor, including one that possesses a tetrahedral C atom in the terminal pyrrole ring. The enzyme porphobilinogen deaminase (PBGD; hydroxymethylbilane synthase; EC 2.5.1.61) catalyses an early step of the tetrapyrrole-biosynthesis pathway in which four molecules of the monopyrrole porphobilinogen are condensed to form a linear tetrapyrrole. The enzyme possesses a dipyrromethane cofactor, which is covalently linked by a thioether bridge to an invariant cysteine residue (Cys241 in the Bacillus megaterium enzyme). The cofactor is extended during the reaction by the sequential addition of the four substrate molecules, which are released as a linear tetrapyrrole product. Expression in Escherichia coli of a His-tagged form of B. megaterium PBGD has permitted the X-ray analysis of the enzyme from this species at high resolution, showing that the cofactor becomes progressively oxidized to the dipyrromethene and dipyrromethanone forms. In previously solved PBGD structures, the oxidized cofactor is in the dipyromethenone form, in which both pyrrole rings are approximately coplanar. In contrast, the oxidized cofactor in the B. megaterium enzyme appears to be in the dipyrromethanone form, in which the C atom at the bridging α-position of the outer pyrrole ring is very clearly in a tetrahedral configuration. It is suggested that the pink colour of the freshly purified protein is owing to the presence of the dipyrromethene form of the cofactor which, in the structure reported here, adopts the same conformation as the fully reduced dipyrromethane form

  15. Habitual Coffee Consumption Does Not Correlate with Blood Pressure, Inflammation and Endothelial Dysfunction but Partially Correlates with Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Erizal Sugiono

    2013-04-01

    Full Text Available BACKGROUND: Coffee is the most widely consumed beverage in the world and has been known to have effects on cardiovascular system. Many researchers have examined the effects of coffee consumption on blood pressure (BP and risk of cardiovascular disease (CVD, but their results were inconsistent and still remain a subject of controversy. Oxidative stress, inflammation, and endothelial dysfunction have been known as risk factors of hypertension and CVD. Those factors are also known to be affected by coffee consumption. The aim of this study was to examine the relationship between the effects of habitual coffee consumption on BP and to examine the role of oxidative stress (F2 isoprostane, inflammation (high sensitive C-reactive protein (hsCRP and endothelial dysfunction (asymmetric dimethylarginine (ADMA. METHODS: This was a cross-sectional study in which 47 healthy, non-smoking men aged 30-60 years with varying coffee-drinking habits were enrolled. BP and blood/urine analysis of biomarkers were measured in the morning before activity. Coffee consumption was assessed using a questionnaire. The differences among variables were analyzed using ANOVA and the correlations between variables were analyzed using Kendall’s Tau correlation analysis. RESULTS: Habitual coffee consumption did not correlate with systolic/diastolic BP (r=-0.02; p=0.856 and r=0.15; p=0.230, respectively. Concentrations of ADMA and hsCRP were also not correlated with coffee consumption (r=0.03; p=0.764 and r=0.04; p=0.701, respectively. Coffee consumption only showed significant correlation with F2 isoprostane (r=0.34; p=0.004. CONCLUSIONS: BP was not affected by coffee consumption although coffee consumption has a significant correlation with F2 isoprostane. These findings suggest that correlation between coffee consumption and BP might be explained by other factors that were not included in this study. KEYWORDS: coffee, caffeine, cardiovascular disease, blood pressure, oxidative

  16. Oxygen Partial Pressure Impact on Characteristics of Indium Titanium Zinc Oxide Thin Film Transistor Fabricated via RF Sputtering.

    Science.gov (United States)

    Hsu, Ming-Hung; Chang, Sheng-Po; Chang, Shoou-Jinn; Wu, Wei-Ting; Li, Jyun-Yi

    2017-06-26

    Indium titanium zinc oxide (InTiZnO) as the channel layer in thin film transistor (TFT) grown by RF sputtering system is proposed in this work. Optical and electrical properties were investigated. By changing the oxygen flow ratio, we can suppress excess and undesirable oxygen-related defects to some extent, making it possible to fabricate the optimized device. XPS patterns for O 1s of InTiZnO thin films indicated that the amount of oxygen vacancy was apparently declined with the increasing oxygen flow ratio. The fabricated TFTs showed a threshold voltage of -0.9 V, mobility of 0.884 cm²/Vs, on-off ratio of 5.5 × 10⁵, and subthreshold swing of 0.41 V/dec.

  17. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    Directory of Open Access Journals (Sweden)

    Sales F.G.

    2004-01-01

    Full Text Available In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM applied to the liquid phase.

  18. Nitrous oxide reduction genetic potential from the microbial community of an intermittently aerated partial nitritation SBR treating mature landfill leachate.

    Science.gov (United States)

    Gabarró, J; Hernández-Del Amo, E; Gich, F; Ruscalleda, M; Balaguer, M D; Colprim, J

    2013-12-01

    This study investigates the microbial community dynamics in an intermittently aerated partial nitritation (PN) SBR treating landfill leachate, with emphasis to the nosZ encoding gene. PN was successfully achieved and high effluent stability and suitability for a later anammox reactor was ensured. Anoxic feedings allowed denitrifying activity in the reactor. The influent composition influenced the mixed liquor suspended solids concentration leading to variations of specific operational rates. The bacterial community was low diverse due to the stringent conditions in the reactor, and was mostly enriched by members of Betaproteobacteria and Bacteroidetes as determined by 16S rRNA sequencing from excised DGGE melting types. The qPCR analysis for nitrogen cycle-related enzymes (amoA, nirS, nirK and nosZ) demonstrated high amoA enrichment but being nirS the most relatively abundant gene. nosZ was also enriched from the seed sludge. Linear correlation was found mostly between nirS and the organic specific rates. Finally, Bacteroidetes sequenced in this study by 16S rRNA DGGE were not sequenced for nosZ DGGE, indicating that not all denitrifiers deal with complete denitrification. However, nosZ encoding gene bacteria was found during the whole experiment indicating the genetic potential to reduce N2O. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Carvedilol alleviates adjuvant-induced arthritis and subcutaneous air pouch edema: Modulation of oxidative stress and inflammatory mediators

    International Nuclear Information System (INIS)

    Arab, Hany H.; El-Sawalhi, Maha M.

    2013-01-01

    Rheumatoid arthritis (RA) is a systemic inflammatory disease with cardiovascular complications as the leading cause of morbidity. Carvedilol is an adrenergic antagonist which has been safely used in treatment of several cardiovascular disorders. Given that carvedilol has powerful antioxidant/anti-inflammatory properties, we aimed to investigate its protective potential against arthritis that may add further benefits for its clinical usefulness especially in RA patients with concomitant cardiovascular disorders. Two models were studied in the same rat; adjuvant arthritis and subcutaneous air pouch edema. Carvedilol (10 mg/kg/day p.o. for 21 days) effectively suppressed inflammation in both models with comparable efficacy to the standard anti-inflammatory diclofenac (5 mg/kg/day p.o.). Notably, carvedilol inhibited paw edema and abrogated the leukocyte invasion to air pouch exudates. The latter observation was confirmed by the histopathological assessment of the pouch lining that revealed mitigation of immuno-inflammatory cell influx. Carvedilol reduced/normalized oxidative stress markers (lipid peroxides, nitric oxide and protein thiols) and lowered the release of inflammatory cytokines (TNF-α and IL-6), and eicosanoids (PGE 2 and LTB 4 ) in sera and exudates of arthritic rats. Interestingly, carvedilol, per se, didn't present any effect on assessed biochemical parameters in normal rats. Together, the current study highlights evidences for the promising anti-arthritic effects of carvedilol that could be mediated through attenuation of leukocyte migration, alleviation of oxidative stress and suppression of proinflammatory cytokines and eicosanoids. - Highlights: ► Carvedilol possesses promising anti-arthritic properties. ► It markedly suppressed inflammation in adjuvant arthritis and air pouch edema. ► It abrogated the leukocyte invasion to air pouch exudates and linings. ► It reduced/normalized oxidative stress markers in sera and exudates of arthritic rats

  20. Carvedilol alleviates adjuvant-induced arthritis and subcutaneous air pouch edema: Modulation of oxidative stress and inflammatory mediators

    Energy Technology Data Exchange (ETDEWEB)

    Arab, Hany H., E-mail: hany_h_arab@yahoo.com [Biochemistry Division, Department of Pharmacology and Toxicology, Faculty of Pharmacy, Taif University, Taif (Saudi Arabia); Department of Biochemistry, Faculty of Pharmacy, Cairo University, Cairo (Egypt); El-Sawalhi, Maha M. [Department of Biochemistry, Faculty of Pharmacy, Cairo University, Cairo (Egypt)

    2013-04-15

    Rheumatoid arthritis (RA) is a systemic inflammatory disease with cardiovascular complications as the leading cause of morbidity. Carvedilol is an adrenergic antagonist which has been safely used in treatment of several cardiovascular disorders. Given that carvedilol has powerful antioxidant/anti-inflammatory properties, we aimed to investigate its protective potential against arthritis that may add further benefits for its clinical usefulness especially in RA patients with concomitant cardiovascular disorders. Two models were studied in the same rat; adjuvant arthritis and subcutaneous air pouch edema. Carvedilol (10 mg/kg/day p.o. for 21 days) effectively suppressed inflammation in both models with comparable efficacy to the standard anti-inflammatory diclofenac (5 mg/kg/day p.o.). Notably, carvedilol inhibited paw edema and abrogated the leukocyte invasion to air pouch exudates. The latter observation was confirmed by the histopathological assessment of the pouch lining that revealed mitigation of immuno-inflammatory cell influx. Carvedilol reduced/normalized oxidative stress markers (lipid peroxides, nitric oxide and protein thiols) and lowered the release of inflammatory cytokines (TNF-α and IL-6), and eicosanoids (PGE{sub 2} and LTB{sub 4}) in sera and exudates of arthritic rats. Interestingly, carvedilol, per se, didn't present any effect on assessed biochemical parameters in normal rats. Together, the current study highlights evidences for the promising anti-arthritic effects of carvedilol that could be mediated through attenuation of leukocyte migration, alleviation of oxidative stress and suppression of proinflammatory cytokines and eicosanoids. - Highlights: ► Carvedilol possesses promising anti-arthritic properties. ► It markedly suppressed inflammation in adjuvant arthritis and air pouch edema. ► It abrogated the leukocyte invasion to air pouch exudates and linings. ► It reduced/normalized oxidative stress markers in sera and exudates of

  1. Vascular ATP-sensitive potassium channels are over-expressed and partially regulated by nitric oxide in experimental septic shock.

    Science.gov (United States)

    Collin, Solène; Sennoun, Nacira; Dron, Anne-Gaëlle; de la Bourdonnaye, Mathilde; Montemont, Chantal; Asfar, Pierre; Lacolley, Patrick; Meziani, Ferhat; Levy, Bruno

    2011-05-01

    To study the activation and expression of vascular (aorta and small mesenteric arteries) potassium channels during septic shock with or without modulation of the NO pathway. Septic shock was induced in rats by peritonitis. Selective inhibitors of vascular K(ATP) (PNU-37883A) or BK(Ca) [iberiotoxin (IbTX)] channels were used to demonstrate their involvement in vascular hyporeactivity. Vascular response to phenylephrine was measured on aorta and small mesenteric arteries mounted on a wire myograph. Vascular expression of potassium channels was studied by PCR and Western blot, in the presence or absence of 1400W, an inducible NO synthase (iNOS) inhibitor. Aortic activation of the transcriptional factor nuclear factor-kappaB (NF-κB) was assessed by electrophoretic mobility shift assay. Arterial pressure as well as in vivo and ex vivo vascular reactivity were reduced by sepsis and improved by PNU-37883A but not by IbTX. Sepsis was associated with an up-regulation of mRNA and protein expression of vascular K(ATP) channels, while expression of vascular BK(Ca) channels remained unchanged. Selective iNOS inhibition blunted the sepsis-induced increase in aortic NO, decreased NF-κB activation, and down-regulated vascular K(ATP) channel expression. Vascular K(ATP) but not BK(Ca) channels are activated, over-expressed, and partially regulated by NO via NF-κB activation during septic shock. Their selective inhibition restores arterial pressure and vascular reactivity and decreases lactate concentration. The present data suggest that selective vascular K(ATP) channel inhibitors offer potential therapeutic perspectives for septic shock.

  2. BL153 Partially Prevents High-Fat Diet Induced Liver Damage Probably via Inhibition of Lipid Accumulation, Inflammation, and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2014-01-01

    Full Text Available The present study was to investigate whether a magnolia extract, named BL153, can prevent obesity-induced liver damage and identify the possible protective mechanism. To this end, obese mice were induced by feeding with high fat diet (HFD, 60% kcal as fat and the age-matched control mice were fed with control diet (10% kcal as fat for 6 months. Simultaneously these mice were treated with or without BL153 daily at 3 dose levels (2.5, 5, and 10 mg/kg by gavage. HFD feeding significantly increased the body weight and the liver weight. Administration of BL153 significantly reduced the liver weight but without effects on body weight. As a critical step of the development of NAFLD, hepatic fibrosis was induced in the mice fed with HFD, shown by upregulating the expression of connective tissue growth factor and transforming growth factor beta 1, which were significantly attenuated by BL153 in a dose-dependent manner. Mechanism study revealed that BL153 significantly suppressed HFD induced hepatic lipid accumulation and oxidative stress and slightly prevented liver inflammation. These results suggest that HFD induced fibrosis in the liver can be prevented partially by BL153, probably due to reduction of hepatic lipid accumulation, inflammation and oxidative stress.

  3. Oxidation resistance in air of 1-D SiC (Hi-nicalon) fibre reinforced silicon nitride ceramic matrix composite

    International Nuclear Information System (INIS)

    Dupel, P.; Veyret, J.B.

    1997-01-01

    The oxidation behaviour of a Si 3 N 4 matrix reinforced with SiC fibres (Hi-nicalon) pre-coated with a 400 nm thick pyrolytic carbon layer has been investigated in dry air in the temperature range 800-1500 C. The same study was performed for individual constituents of the composite (fibre and matrix). Two phenomena are observed in the oxidation behaviour of the composite. At low temperature (T<1200 C), the matrix oxidation is negligible, only the carbon interphase was oxidised creating an annular space between the fibres and the matrix throughout the sample. At high temperature (T≥1300 C) the rate of formation of the oxidation products of the matrix is rapid and a sealing effect is observed. While at these temperatures the interphase is protected in the bulk of the material, the time needed to seal the gap between the fibre and the matrix is too long to prevent its oxidation to a significant depth from the surface. Finally, preliminary results are presented where the consumption of the interphase is completely prevented by applying an external coating which gives oxidation protection from low to high temperature. (orig.)

  4. Air pollution alters brain and pituitary endothelin-1 and inducible nitric oxide synthase gene expression.

    Science.gov (United States)

    Thomson, Errol M; Kumarathasan, Prem; Calderón-Garcidueñas, Lilian; Vincent, Renaud

    2007-10-01

    Recent work suggests that air pollution is a risk factor for cerebrovascular and neurodegenerative disease. Effects of inhaled pollutants on the production of vasoactive factors such as endothelin (ET) and nitric oxide (NO) in the brain may be relevant to disease pathogenesis. Inhaled pollutants increase circulating levels of ET-1 and ET-3, and the pituitary is a potential source of plasma ET, but the effects of pollutants on the expression of ET and NO synthase genes in the brain and pituitary are not known. In the present study, Fischer-344 rats were exposed by nose-only inhalation to particles (0, 5, 50mg/m3 EHC-93), ozone (0, 0.4, 0.8 ppm), or combinations of particles and ozone for 4 h. Real-time reverse transcription polymerase chain reaction was used to measure mRNA levels in the cerebral hemisphere and pituitary 0 and 24 h post-exposure. Ozone inhalation significantly increased preproET-1 but decreased preproET-3 mRNAs in the cerebral hemisphere, while increasing mRNA levels of preproET-1, preproET-3, and the ET-converting enzyme (ECE)-1 in the pituitary. Inducible NO synthase (iNOS) was initially decreased in the cerebral hemisphere after ozone inhalation, but increased 24 h post-exposure. Particles decreased tumour necrosis factor (TNF)-alpha mRNA in the cerebral hemisphere, and both particles and ozone decreased TNF-alpha mRNA in the pituitary. Our results show that ozone and particulate matter rapidly modulate the expression of genes involved in key vasoregulatory pathways in the brain and pituitary, substantiating the notion that inhaled pollutants induce cerebrovascular effects.

  5. Review of research results for the photocatalytic oxidation of hazardous wastes in air

    Energy Technology Data Exchange (ETDEWEB)

    Nimlos, M R; Wolfrum, E J; Gratson, D A; Watt, A S; Jacoby, W A; Turchi, C

    1995-01-01

    Laboratory experiments of gas-phase photocatalytic oxidation (PCO) at NREL have focused on measurements that can help commercialize this technology for treating gaseous air streams. This effort proceeds earlier NREL work and studies conducted elsewhere which demonstrated the general applicability of PCO. The more recent work has concentrated on: (1) the kinetics of the PCO process; (2) the formation and destruction of intermediates; and (3) possible enhancements to improve the destruction rates. The results from these studies will be used to help design large scale PCO equipment and they will be used to evaluate the economics of the PCO process. For trichloroethylene and ethanol, extensive studies of the rates of destruction have yielded kinetic parameters for the destruction of intermediates as well as the substrate. The kinetics of intermediates is essential for sizing a large scale reactor, as complete conversion to carbon dioxide is often desired. The kinetic data from these laboratory studies has been used for analyzing IT`s pilot PCO reactor and has been used to suggest modifications to this unit. For compounds that are more difficult to destroy (such as the components of BTEX), rate enhancement experiments have been conducted. These compounds represent a very large market for this technology and improvement of the rate of the process should make it competitive. Towards this goal, the enhancement of the destruction of BTEX components have been studied. Experiments have demonstrated that there is a significant increase in the rates of destruction of BTEX with the addition of ozone. Preliminary economic assessments have shown that PCO with ozone may be cost competitive. Future laboratory experiments of PCO will focus on refinements of what has been learned. Rate measurements will also be expanded to include other compounds representing significant markets for the PCO technology.

  6. Oxygen-Rich Lithium Oxide Phases Formed at High Pressure for Potential Lithium-Air Battery Electrode.

    Science.gov (United States)

    Yang, Wenge; Kim, Duck Young; Yang, Liuxiang; Li, Nana; Tang, Lingyun; Amine, Khalil; Mao, Ho-Kwang

    2017-09-01

    The lithium-air battery has great potential of achieving specific energy density comparable to that of gasoline. Several lithium oxide phases involved in the charge-discharge process greatly affect the overall performance of lithium-air batteries. One of the key issues is linked to the environmental oxygen-rich conditions during battery cycling. Here, the theoretical prediction and experimental confirmation of new stable oxygen-rich lithium oxides under high pressure conditions are reported. Three new high pressure oxide phases that form at high temperature and pressure are identified: Li 2 O 3 , LiO 2 , and LiO 4 . The LiO 2 and LiO 4 consist of a lithium layer sandwiched by an oxygen ring structure inherited from high pressure ε-O 8 phase, while Li 2 O 3 inherits the local arrangements from ambient LiO 2 and Li 2 O 2 phases. These novel lithium oxides beyond the ambient Li 2 O, Li 2 O 2 , and LiO 2 phases show great potential in improving battery design and performance in large battery applications under extreme conditions.

  7. Effects of thermal treatment on mineralogy and heavy metal behavior in iron oxide stabilized air pollution control residues

    DEFF Research Database (Denmark)

    Sørensen, Mette Abildgaard; Bender-Koch, C.; Starckpoole, M. M.

    2000-01-01

    Stabilization of air pollution control residues by coprecipitation with ferrous iron and subsequent thermal treatment (at 600 and 900 °C) has been examined as a means to reduce heavy metal leaching and to improve product stability. Changes in mineralogy and metal binding were analyzed using various...... analytical and environmental techniques. Ferrihydrite was formed initially but transformed upon thermal treatment to more stable and crystalline iron oxides (maghemite and hematite). For some metals leaching studies showed more substantial binding after thermal treatment, while other metals either....... Thermal treatment of the stabilized residues produced structures with an inherently better iron oxide stability. However, the concentration of metals in the leachate generally increased as a consequence of the decreased solubility of metals in the more stable iron oxide structure....

  8. β-Naphthoflavone enhances oxidative stress responses and the induction of preneoplastic lesions in a diethylnitrosamine-initiated hepatocarcinogenesis model in partially hepatectomized rats

    International Nuclear Information System (INIS)

    Dewa, Yasuaki; Nishimura, Jihei; Muguruma, Masako; Jin, Meilan; Saegusa, Yukie; Okamura, Toshiya; Tasaki, Masako; Umemura, Takashi; Mitsumori, Kunitoshi

    2008-01-01

    The tumour-promoting effects of β-naphthoflavone (BNF), a novel aryl hydrocarbon receptor (AhR) agonist, were investigated using a medium-term hepatocarcinogenesis model in rats. Six-week-old male F344 rats received an intraperitoneal injection of N-diethylnitrosamine (DEN) at a dose of 200 mg/kg body weight and were fed a diet containing 0% (basal diet), 0.5% or 1% BNF for 6 weeks from 2 weeks after DEN treatment. All animals were subjected to two-thirds partial hepatectomy 1 week after the BNF treatment. The number and area of glutathione S-transferase placental form (GST-P) positive foci significantly increased in the livers of rats treated with BNF with concomitantly increased cell proliferation compared to those in the livers of the DEN alone group. Global gene expression analysis and subsequent quantitative real-time reverse transcription-polymerase chain reaction revealed that BNF induced not only the 'AhR gene battery'Cyp1a1, Cyp1a2, Cyp1b1, Nqo1, Aldh3a1 and Ugt1a6 but also the transcription factor NF-E2-related factor 2 (Nrf2)-regulated genes such as Gstm1, Gpx2, Akr7a3 and Yc2 (and also Nqo1), presumably due to the adaptive response against BNF-triggered oxidative stress responses. Reactive oxygen species production increased in microsomes isolated from the livers of BNF-treated rats, and this enhancement was suppressed by the P450 inhibitor SKF-525A. Furthermore, BNF enhanced oxidative DNA damage and lipid peroxidation, estimated by the levels of 8-hydroxydeoxyguanosine (8-OHdG) and thiobarbituric acid-reactive substances. These results suggest that the administration of BNF at a high dose and over a long-term enhance oxidative stress responses which may contribute to its hepatocarcinogenic potential in rats

  9. Nitric Oxide and Oxygen Air-Contamination Effects on Extinction Limits of Non-Premixed Hydrocarbon-Air Flames for a HIFiRE Scramjet

    Science.gov (United States)

    Pellett, Gerald L.; Dawson, Lucy C.; Vaden, Sarah N.; Wilson, Lloyd G.

    2009-01-01

    Unique nitric oxide (NO) and oxygen air-contamination effects on the extinction Flame Strength (FS) of non-premixed hydrocarbon (HC) vs. air flames are characterized for 7 gaseous HCs, using a new idealized 9.3 mm straight-tube Opposed Jet Burner (OJB) at 1 atm. FS represents a laminar strain-induced extinction limit based on cross-section-average air jet velocity, Uair, that sustains combustion of a counter jet of gaseous fuel just before extinction. Besides ethane, propane, butane, and propylene, the HCs include ethylene, methane, and a 64 mole-% ethylene / 36 % methane mixture, the writer s previously recommended gaseous surrogate fuel for HIFiRE scramjet tests. The HC vs. clean air part of the work is an extension of a May 2008 JANNAF paper that characterized surrogates for the HIFiRE project that should mimic the flameholding of reformed (thermally- or catalytically-cracked) endothermic JP-like fuels. The new FS data for 7 HCs vs. clean air are thus consolidated with the previously validated data, normalized to absolute (local) axial-input strain rates, and co-plotted on a dual kinetically dominated reactivity scale. Excellent agreement with the prior data is obtained for all 7 fuels. Detailed comparisons are also made with recently published (Univ. Va) numerical results for ethylene extinction. A 2009-revised ethylene kinetic model (Univ. Southern Cal) led to predicted limits within approx. 5 % (compared to 45 %, earlier) of this writer s 2008 (and present) ethylene FSs, and also with recent independent data (Univ. Va) obtained on a new OJB system. These +/- 5 % agreements, and a hoped-for "near-identically-performing" reduced kinetics model, would greatly enhance the capability for accurate numerical simulations of surrogate HC flameholding in scramjets. The measured air-contamination effects on normalized FS extinction limits are projected to assess ongoing Arc-Heater-induced "facility test effects" of NO production (e.g., 3 mole-%) and resultant oxygen

  10. Oxidation-induced crack healing in Ti3AlC2 ceramics

    NARCIS (Netherlands)

    Song, G.M.; Pei, Y.T.; Sloof, W.G.; Li, S.B.; Hosson, J.Th.M. De; Zwaag, S. van der

    Crack healing of Ti3AlC2 was investigated by oxidizing a partially pre-cracked sample. A crack near a notch was introduced into the sample by tensile deformation. After oxidation at 1100 degrees C in air for 2 h, the crack was completely healed, with oxidation products consisting primarily of

  11. A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells

    Science.gov (United States)

    Lan, Rong; Cowin, Peter I.; Sengodan, Sivaprakash; Tao, Shanwen

    2016-08-01

    Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3-δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3-δ (SFCN) exhibits a conductivity of 63 Scm-1and 60 Scm-1 at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3-δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3-δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3-δ as the cathode achieved a power density of 423 mWcm-2 at 700 °C indicating that SFCN is a promising anode for SOFCs.

  12. Improved Thermally Grown Oxide Scale in Air Plasma Sprayed NiCrAlY/Nano-YSZ Coatings

    International Nuclear Information System (INIS)

    Daroonparvar, M.; Yajid, M.A.M.; Yusof, N.M.; Hussain, M.S.

    2013-01-01

    Oxidation has been considered as one of the principal disruptive factors in thermal barrier coating systems during service. So, oxidation behavior of thermal barrier coating (TBC) systems with nano structured and micro structured YSZ coatings was investigated at 1000 degree c for 24 h, 48 h, and 120 h. Air plasma sprayed nano-YSZ coating exhibited a tri modal structure. Microstructural characterization also demonstrated an improved thermally grown oxide scale containing lower spinels in nano-TBC system after 120 h of oxidation. This phenomenon is mainly related to the unique structure of the nano-YSZ coating, which acted as a strong barrier for oxygen diffusion into the TBC system at elevated temperatures. Nearly continues but thinner Al 2 O 3 layer formation at the NiCrAlY/nano-YSZ interface was seen, due to lower oxygen infiltration into the system. Under this condition, spinels formation and growth on the Al 2 O 3 oxide scale were diminished in nano-TBC system compared to normal TBC system.

  13. Influence of cerium, zirconium and boron on the oxidation resistance of heat-resistant steels in air

    International Nuclear Information System (INIS)

    Gala, A.; Schendler, W.

    1981-01-01

    Isothermal and cyclic oxidation experiments were carried out in air to investigate the influence of the minor elements such as Cerium, Zirkonium and Boron on the oxidation resistance of heat resistant ferritic and austenitic steels like X10Cr18, X10CrAl18 and X15CrNiSi2012. In the case of cyclicexperiments samples were exposed at constant temperatures for 100 h and then cooled to R.T. This cycle was repeated 10 times. The corrosion was determined as weight change and was continuously measured by a thermo-balance. The distribution of the alloying elements on the phase boundary scale/steel was examined by Scanning-Electron-Microscope. Addition of small amounts of Ce (0.3 wt-% max.) could reduce the oxidation rate in the case of isothermal and cyclic conditions. Zirkonium concentrations below 0.1 wt-% could have a beneficial effect, but at higher concentrations the oxidation rate increases with increasing amounts of Zr. Small Boron concentrations of 0.02 wt-% lead to catastrophic oxidation at temperatures above 1000 0 C. (orig.) [de

  14. Partial oxidation of jet fuels over Rh/Al_2O_3. Design and reaction kinetics of sulfur-containing surrogates

    International Nuclear Information System (INIS)

    Baer, Julian Nicolaas

    2016-01-01

    The conversion of logistic fuels via catalytic partial oxidation (CPOX) on Rh/Al_2O_3 at short contact times is an efficient method for generating hydrogen-rich synthesis gas. Depending on the inlet conditions, fuel, and catalyst, high syngas yields, low by-product formation, and rates of high fuel conversion can be achieved. CPOX is relevant for mobile hydrogen generation, e.g., on board of airplanes in order to increase the fuel efficiency via fuel cell-based auxiliary power units. Jet fuels contain hundreds of different hydrocarbons and a significant amount of sulfur. The hydrocarbon composition and sulfur content of a jet fuel vary depending on distributor, origin, and refinement of the crude oil. Little is known about the influence of the various compounds on the synthesis-gas yield and the impact of sulfur on the product yield. In this work, the influence of three main chemical compounds of a jet fuel (aromatics, alkanes, and sulfur compounds) on syngas selectivity, the catalyst deactivation process, and reaction sequence is unraveled. As representative components of alkanes and aromatics, n-dodecane and 1,2,4-trimethylbenzene were chosen for ex-situ and in-situ investigations on the CPOX over Rh/Al_2O_3, respectively. Additionally, for a fixed paraffin-to-aromatics ratio, benzothiophene or dibenzothiophene were added as a sulfur component in three different concentrations. The knowledge gained about the catalytic partial oxidation of jet fuels and their surrogates is used to identify requirements for jet fuels in mobile applications based on CPOX and to optimize the overall system efficiency. The results show an influence of the surrogate composition on syngas selectivity. The tendency for syngas formation increases with higher paraffin contents. A growing tendency for by-product formation can be observed with increasing aromatics contents in the fuel. The impact of sulfur on the reaction system shows an immediate change in the product distribution. An

  15. Partial oxidation of jet fuels over Rh/Al{sub 2}O{sub 3}. Design and reaction kinetics of sulfur-containing surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Baer, Julian Nicolaas

    2016-07-01

    The conversion of logistic fuels via catalytic partial oxidation (CPOX) on Rh/Al{sub 2}O{sub 3} at short contact times is an efficient method for generating hydrogen-rich synthesis gas. Depending on the inlet conditions, fuel, and catalyst, high syngas yields, low by-product formation, and rates of high fuel conversion can be achieved. CPOX is relevant for mobile hydrogen generation, e.g., on board of airplanes in order to increase the fuel efficiency via fuel cell-based auxiliary power units. Jet fuels contain hundreds of different hydrocarbons and a significant amount of sulfur. The hydrocarbon composition and sulfur content of a jet fuel vary depending on distributor, origin, and refinement of the crude oil. Little is known about the influence of the various compounds on the synthesis-gas yield and the impact of sulfur on the product yield. In this work, the influence of three main chemical compounds of a jet fuel (aromatics, alkanes, and sulfur compounds) on syngas selectivity, the catalyst deactivation process, and reaction sequence is unraveled. As representative components of alkanes and aromatics, n-dodecane and 1,2,4-trimethylbenzene were chosen for ex-situ and in-situ investigations on the CPOX over Rh/Al{sub 2}O{sub 3}, respectively. Additionally, for a fixed paraffin-to-aromatics ratio, benzothiophene or dibenzothiophene were added as a sulfur component in three different concentrations. The knowledge gained about the catalytic partial oxidation of jet fuels and their surrogates is used to identify requirements for jet fuels in mobile applications based on CPOX and to optimize the overall system efficiency. The results show an influence of the surrogate composition on syngas selectivity. The tendency for syngas formation increases with higher paraffin contents. A growing tendency for by-product formation can be observed with increasing aromatics contents in the fuel. The impact of sulfur on the reaction system shows an immediate change in the product

  16. Air oxidation and biodegradation of the organic matter from the Boom Claycomparison between artificial and natural altered series

    International Nuclear Information System (INIS)

    Blanchart, Pascale; Faure, Pierre; Michels, Raymond; Bruggeman, Christophe; De Craen, Mieke

    2010-01-01

    Document available in extended abstract form only. The Boom Clay formation (Belgium) is studied as the reference host rock for methodological studies on the geological disposal of high-level and long-lived radioactive waste. The drilling of galleries in the Boom Clay at Mol lead to the perturbation of the initial physical and chemical conditions. Since organic matter is present in this argillaceous formation, it is important to know its response to these new conditions. The Boom Clay is of Tertiary age (Rupelian) and has a TOC content up to 5%. Its pore water (20% in mass of rock) contains significant quantities of Dissolved Organic Carbon (DOC) with a mean concentration of 115+/-15 mg/L, determined on the basis of piezometer water as well as squeezing and leaching experiments. Yet, in piezometers, the DOC may show considerable and irregular variations through time, with values ranging between 80 and 425 mg/L. The origin and bio-physico-chemical controls of such variations are yet unknown. Perturbation of the in-situ conditions of the clay is a possible reason for such observation. More likely the introduction of air as well as micro-organisms may have an impact that needs to be estimated. Well-preserved, freshly-drilled Boom Clay samples, as well as samples of different degrees of alteration (air exposed clay from the older galleries) were collected with the aim of determining and quantifying different molecular markers representative for the alteration degree. Additionally, increasing artificial air oxidation experiments were carried out on fresh Praclay samples (sampled during the PRACLAY gallery excavation) in order to obtain an altered reference series. Moreover PRACLAY samples previously extracted with an organic solvent (dichloromethane) were also prepared in order to identify the influence of the kerogen during oxidation. In these experiments, powdered clay was heated at 80 deg. C under air flow during 1, 3, 6, 9, 12, 18 months. Organic matter composition

  17. Preliminary assessment of air quality for sulphur dioxide, nitrogen dioxide, nitrogen oxides, particulate matter, and lead in the Netherlands under European legislation

    NARCIS (Netherlands)

    Breugel PB van; Buijsman E; LLO

    2001-01-01

    The current air quality in the Netherlands for sulphur dioxide, nitrogen dioxide, nitrogen oxides, particulate matter and lead has been assessed in the context of limit values, margins of tolerance and the assessment thresholds used in the first daughter directive for air quality of the European

  18. The crystallographic structure of the air-grown oxide on depleted uranium metal

    International Nuclear Information System (INIS)

    Jones, Christopher P.; Petherbridge, James R.; Davis, Sean A.; Jones, Jonathon A.; Scott, Thomas B.

    2016-01-01

    Highlights: • Oxidation of depleted uranium coupons under ambient conditions and 150 °C. • Oxide characterised using SEM, TEM and electron backscatter diffraction analysis, • Layer comprises of UO 2 crystallites 12 nm in diameter. • Preferred [110] growth direction normal to the surface of the metal. • Oxide growth direction is independent of the underlying crystal orientation. - Abstract: Oxide formation on depleted uranium metal was investigated using a combination of electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) characterisation. Diffraction analysis of the oxide revealed an FCC crystalline formation of UO 2 crystallites whilst TEM data indicated an average grain size of 12 nm with a standard deviation of 3.8 nm. EBSD analysis revealed a preferential texture of [110] normal to the surface of the metal. This data implied that lattice matching between the oxide and the underlying metal did not occur, therefore, the observed preferential growth direction is independent of the underlying crystal orientation.

  19. Formation of acetic acid by aqueous-phase oxidation of ethanol with air in the presence of a heterogeneous gold catalyst

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Jørgensen, Betina; Hansen, Jeppe Rass

    2006-01-01

    Wine into vinegar: It is possible to selectively oxidize ethanol into acetic acid in aqueous solution with air as the oxidant and a heterogeneous gold catalyst (see TEM image of supported gold particles) at temperatures of about 423 K and O2 pressures of 0.6 MPa. This reaction proceeds readily...