WorldWideScience

Sample records for thermal decomposition

  1. Thermal decomposition of hemicelluloses

    OpenAIRE

    Werner, Kajsa; Pommer, Linda; Broström, Markus

    2014-01-01

    Decomposition modeling of biomass often uses commercially available xylan as model compound representing hemicelluloses, not taking in account the heterogeneous nature of that group of carbohydrates. In this study, the thermal decomposition behavior of seven different hemicelluloses (beta-glucan, arabinogalactan, arabinoxylan, galactomannan, glucomannan, xyloglucan, and xylan) were investigated in inert atmosphere using (i) thermogravimetric analysis coupled to Fourier transform infrared spec...

  2. Thermal decomposition of illite

    Directory of Open Access Journals (Sweden)

    Araújo José Humberto de

    2004-01-01

    Full Text Available The effect of heat treatment on illite in air at temperatures ranging from 750 to 1150 °C was studied using the Mössbauer effect in 57Fe. The dependence of the Mössbauer parameters and relative percentage of the radiation absorption area was measured as a function of the firing temperature. The onset of thermal structural decomposition occurred at 800 °C. With rising temperature, the formation of hematite (Fe2O3 increased at the expense of the silicate mineral.

  3. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    Keywords. TGA–DTA; FTIR; X-ray diffraction; dolomite. Abstract. Thermal decomposition behaviour of dolomite sample has been studied by thermogravimetric (TG) measurements. Differential thermal analysis (DTA) curve of dolomite shows two peaks at 777.8°C and 834°C. The two endothermic peaks observed in dolomite ...

  4. Thermal decomposition of ammonium hexachloroosmate

    DEFF Research Database (Denmark)

    Asanova, T I; Kantor, Innokenty; Asanov, I. P.

    2016-01-01

    polymeric structure. Being revealed for the first time the intermediate was subjected to determine the local atomic structure around osmium. The thermal decomposition of hexachloroosmate is much more complex and occurs within a minimum two-step process, which has never been observed before....

  5. Preparation, Structure Characterization and Thermal Decomposition ...

    African Journals Online (AJOL)

    NJD

    thermal decomposition process of [Dy(m-MBA)3phen]2·H2O has been followed by thermal analysis. KEYWORDS ... X-ray diffraction, elemental analysis, UV and IR spectroscopy, .... diffractometer with graphite-monochromated Mo Kα radiation.

  6. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  7. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    TECS

    the effects of experimental variables i.e. sample weight, particle size, purge gas velocity and crystalline structure, ... effect of chlorine ions on the decomposition kinetics of dolomite at various temperatures studied by ... to 1000°C at a heating rate of 10 K/min, (ii) N2-gas dyna- mic atmosphere (90 cm. 3 min. –1. ), (iii) alumina ...

  8. Thermal decomposition and non-isothermal decomposition kinetics of carbamazepine

    Science.gov (United States)

    Qi, Zhen-li; Zhang, Duan-feng; Chen, Fei-xiong; Miao, Jun-yan; Ren, Bao-zeng

    2014-12-01

    The thermal stability and kinetics of isothermal decomposition of carbamazepine were studied under isothermal conditions by thermogravimetry (TGA) and differential scanning calorimetry (DSC) at three heating rates. Particularly, transformation of crystal forms occurs at 153.75°C. The activation energy of this thermal decomposition process was calculated from the analysis of TG curves by Flynn-Wall-Ozawa, Doyle, distributed activation energy model, Šatava-Šesták and Kissinger methods. There were two different stages of thermal decomposition process. For the first stage, E and log A [s-1] were determined to be 42.51 kJ mol-1 and 3.45, respectively. In the second stage, E and log A [s-1] were 47.75 kJ mol-1 and 3.80. The mechanism of thermal decomposition was Avrami-Erofeev (the reaction order, n = 1/3), with integral form G(α) = [-ln(1 - α)]1/3 (α = ˜0.1-0.8) in the first stage and Avrami-Erofeev (the reaction order, n = 1) with integral form G(α) = -ln(1 - α) (α = ˜0.9-0.99) in the second stage. Moreover, Δ H ≠, Δ S ≠, Δ G ≠ values were 37.84 kJ mol-1, -192.41 J mol-1 K-1, 146.32 kJ mol-1 and 42.68 kJ mol-1, -186.41 J mol-1 K-1, 156.26 kJ mol-1 for the first and second stage, respectively.

  9. Lignin Derivatives Formation In Catalysed Thermal Decomposition ...

    African Journals Online (AJOL)

    denise

    in the heat of gasification and mass fraction of non-combustible volatiles in solid. NaOH-catalysed thermal decomposition of pure and fire-retardant- cellulose. Kuroda and co-workers14 studied the Curie-point pyrolysis of Japanese softwood species of the red pine, cedar and cypress in the presence of inorganic substances ...

  10. Thermal decomposition of lead titanyl oxalate tetrahydrate

    NARCIS (Netherlands)

    van de Velde, G.M.H.; Oranje, P.J.D.

    1976-01-01

    The thermal behaviour of PbTiO(C2O4)2·4H2O (PTO) has been investigated, employing TG, quantitative DTA, infrared spectroscopy and (high temperature) X-ray powder diffraction. The decomposition involves four main steps. The first is the dehydration of the tetrahydrate (30–180°C), followed by a small

  11. Thermal decompositions of light lanthanide aconitates

    Energy Technology Data Exchange (ETDEWEB)

    Brzyska, W.; Ozga, W. (Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland))

    The conditions of thermal decomposition of Y, La, Ce(III), Pr, Nd, Sm, and Gd aconitates have been studied. On heating, the aconitate of Ce(III) loses crystallization water to yield anhydrous salt, which then is transformed to oxide CeO/sub 2/. The aconitates of Y, Pr, Nd, Sm, Eu and Gd decompose in three stages. First, aconitates undergo dehydration to form the anhydrous salts, which next decompose to Ln/sub 2/O/sub 2/CO/sub 3/. In the last stage the thermal decomposition of Ln/sub 2/O/sub 2/CO/sub 3/ is accompanied by endothermic effect. Dehydration of aconitate of La undergoes in two stages. The anhydrous complex decomposes to La/sub 2/O/sub 2/CO/sub 3/; this subsequently decomposes to La/sub 2/O/sub 3/.

  12. Thermal Decomposition of IMX-104: Ingredient Interactions Govern Thermal Insensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Maharrey, Sean [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wiese-Smith, Deneille [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Highley, Aaron M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Steill, Jeffrey D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Behrens, Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kay, Jeffrey J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-04-01

    This report summarizes initial studies into the chemical basis of the thermal insensitivity of INMX-104. The work follows upon similar efforts investigating this behavior for another DNAN-based insensitive explosive, IMX-101. The experiments described demonstrate a clear similarity between the ingredient interactions that were shown to lead to the thermal insensitivity observed in IMX-101 and those that are active in IMX-104 at elevated temperatures. Specifically, the onset of decomposition of RDX is shifted to a lower temperature based on the interaction of the RDX with liquid DNAN. This early onset of decomposition dissipates some stored energy that is then unavailable for a delayed, more violent release.

  13. Thermal decomposition of meat and bone meal

    Energy Technology Data Exchange (ETDEWEB)

    Conesa, J.A.; Fullana, A.; Font, R. [Department of Chemical Engineering, University of Alicante, P.O. Box 99, E-03080 Alicante (Spain)

    2003-12-01

    A series of runs has been performed to study the thermal behavior of meat and bone meal (MBM) both in inert and reactive atmosphere. Although they are actually burned, the thermal decomposition of such MBM wastes has not been studied from a scientific point of view until now. The aim of this work is to present and discuss the thermogravimetric behavior of MBM both in nitrogen and air atmospheres. A thermobalance has been used to carry out the study at three different heating rates. A kinetic scheme able to correlate simultaneously (with no variation of the kinetic constants) the runs performed at different heating rates and different atmospheres of reaction is presented.

  14. Modeling yields insight into thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Case, J.L.; Carr, R.V.; Simpson, M.S. [Air Products and Chemicals, Inc., Allentown, PA (United States)

    1995-12-01

    A fundamental understanding of the thermal decomposition of nitrotoluenes is critical in evaluating the hazards associated with transporting and storing commercial volumes of these chemicals. Detailed modeling of an adiabatic, low PHI and semi-open (vented to a larger pressure vessel) calorimeter provides insight into a multiple reaction mechanism. The reaction rates developed, along with the significant effect of reactant or intermediates vaporization were confirmed with additional experimental results. Such an interpretation of nitrotoluene decomposition is consistent with recent isothermal experiments as well as with the body of data reported in the open literature. The low temperature or induction reactions are accurately represented with a first order Arrhenius model having typical values for kinetic and thermodynamic parameters. These reactions generate minimal amounts of non condensable gas. If the material is maintained at an elevated temperature, but prevented from self-heating (by external cooling), the intermediate products form thermally unstable and nonvolatile oligomers. At higher temperatures the remaining materials undergo explosive reactions characterized by high heats of reaction, large activation energies and massive releases of non condensable gas. Quantifying the rates of nitrotoluene and/or intermediate vaporization versus oligomerization is essential in evaluating the hazard of a thermal explosion involving a commercial quantity of nitrotoluene.

  15. Thermal decomposition as route for silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Navaladian S

    2006-01-01

    Full Text Available AbstractSingle crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.

  16. Thermal decompositions of heavy lanthanide aconitates

    Energy Technology Data Exchange (ETDEWEB)

    Brzyska, W.; Ozga, W. (Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland))

    The conditions of thermal decomposition of Tb(III), Dy, Ho, Er, Tm, Yb and Lu aconitates have been studied. On heating, the aconitates of heavy lanthanides lose crystallization water to yield anhydrous salts, which are then transformed into oxides. The aconitate of Tb(III) decomposes in two stages. First, the complex undergoes dehydration to form the anhydrous salt, which next decomposes directly to Tb/sub 4/O/sub 7/. The aconitates of Dy, Ho, Er, Tm, Yb and Lu decompose in three stages. On heating, the hydrated complexes lose crystallization water, yielding the anhydrous complexes; these subsequently decompose to Ln/sub 2/O/sub 3/ with intermediate formation of Ln/sub 2/O/sub 2/CO/sub 3/.

  17. Thermal Decomposition of Radiation-Damaged Polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    J Abrefah GS Klinger

    2000-09-26

    The radiation-damaged polystyrene material (''polycube'') used in this study was synthesized by mixing a high-density polystyrene (''Dylene Fines No. 100'') with plutonium and uranium oxides. The polycubes were used on the Hanford Site in the 1960s for criticality studies to determine the hydrogen-to-fissile atom ratios for neutron moderation during processing of spent nuclear fuel. Upon completion of the studies, two methods were developed to reclaim the transuranic (TRU) oxides from the polymer matrix: (1) burning the polycubes in air at 873 K; and (2) heating the polycubes in the absence of oxygen and scrubbing the released monomer and other volatile organics using carbon tetrachloride. Neither of these methods was satisfactory in separating the TRU oxides from the polystyrene. Consequently, the remaining polycubes were sent to the Hanford Plutonium Finishing Plant (PFP) for storage. Over time, the high dose of alpha and gamma radiation has resulted in a polystyrene matrix that is highly cross-linked and hydrogen deficient and a stabilization process is being developed in support of Defense Nuclear Facility Safety Board Recommendation 94-1. Baseline processes involve thermal treatment to pyrolyze the polycubes in a furnace to decompose the polystyrene and separate out the TRU oxides. Thermal decomposition products from this degraded polystyrene matrix were characterized by Pacific Northwest National Laboratory to provide information for determining the environmental impact of the process and for optimizing the process parameters. A gas chromatography/mass spectrometry (GC/MS) system coupled to a horizontal tube furnace was used for the characterization studies. The decomposition studies were performed both in air and helium atmospheres at 773 K, the planned processing temperature. The volatile and semi-volatile organic products identified for the radiation-damaged polystyrene were different from those observed for virgin

  18. Thermal Decomposition of Radiation-Damaged Polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Abrefah, John; Klinger, George S.

    2000-09-26

    The radiation-damaged polystyrene (given the identification name of 'polycube') was fabricated by mixing high-density polystyrene material ("Dylene Fines # 100") with plutonium and uranium oxides. The polycubes were used in the 1960s for criticality studies during processing of spent nuclear fuel. The polycubes have since been stored for almost 40 years at the Hanford Plutonium Finishing Plant (PFP) after failure of two processes to reclaim the plutonium and uranium oxides from the polystyrene matrix. Thermal decomposition products from this highly cross-linked polystyrene matrix were characterized using Gas Chromatograph/Mass Spectroscopy (GC/MS) system coupled to a horizontal furnace. The decomposition studies were performed in air and helium atmospheres at about 773 K. The volatile and semi-volatile organic products for the radiation-damaged polystyrene were different compared to virgin polystyrene. The differences were in the number of organic species generated and their concentrations. In the inert (i.e., helium) atmosphere, the major volatile organic products identified (in order of decreasing concentrations) were styrene, benzene, toluene, ethylbenzene, xylene, nathphalene, propane, .alpha.-methylbenzene, indene and 1,2,3-trimethylbenzene. But in air, the major volatile organic species identified changed slightly. Concentrations of the organic species in the inert atmosphere were significantly higher than those for the air atmosphere processing. Overall, 38 volatile organic species were identified in the inert atmosphere compared to 49 species in air. Twenty of the 38 species in the inert conditions were also products in the air atmosphere. Twenty-two oxidized organic products were identified during thermal processing in air.

  19. Dissociative Ionization and Thermal Decomposition of Cyclopentanone.

    Science.gov (United States)

    Pastoors, Johan I M; Bodi, Andras; Hemberger, Patrick; Bouwman, Jordy

    2017-09-21

    Despite the growing use of renewable and sustainable biofuels in transportation, their combustion chemistry is poorly understood, limiting our efforts to reduce harmful emissions. Here we report on the (dissociative) ionization and the thermal decomposition mechanism of cyclopentanone, studied using imaging photoelectron photoion coincidence spectroscopy. The fragmentation of the ions is dominated by loss of CO, C 2 H 4 , and C 2 H 5 , leading to daughter ions at m/z 56 and 55. Exploring the C 5 H 8 O . + potential energy surface reveals hydrogen tunneling to play an important role in low-energy decarbonylation and probably also in the ethene-loss processes, yielding 1-butene and methylketene cations, respectively. At higher energies, pathways without a reverse barrier open up to oxopropenyl and cyclopropanone cations by ethyl-radical loss and a second ethene-loss channel, respectively. A statistical Rice-Ramsperger-Kassel-Marcus model is employed to test the viability of this mechanism. The pyrolysis of cyclopentanone is studied at temperatures ranging from about 800 to 1100 K. Closed-shell pyrolysis products, namely 1,3-butadiene, ketene, propyne, allene, and ethene, are identified based on their photoion mass-selected threshold photoelectron spectrum. Furthermore, reactive radical species such as allyl, propargyl, and methyl are found. A reaction mechanism is derived incorporating both stable and reactive species, which were not predicted in prior computational studies. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  20. Thermal-decomposition studies of HMX

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, J.R.; Garza, R.G.

    1981-10-20

    We have investigated the rates of decomposition as functions of time and temperature on a combined thermogravimetric analyzer-residual gas analyzer (TGA-RGA). This technique also allows us to identify decomposition products generated as the original HMX begins to decompose. The temperature range studied was 50 to 200/sup 0/C. The decomposition process and the nature of decomposition products as functions of HMX polymorphs and conformations of the organic ring systems and possible reactive intermediates are discussed. 7 figures, 3 tables.

  1. Kinetics of the thermal decomposition of tetramethylsilane behind ...

    Indian Academy of Sciences (India)

    Thermal decomposition of tetramethylsilane (TMS) diluted in argon was studied behind the reflected shock waves in a single pulse shock tube (SPST) in the temperature range of 1058–1194 K. The major products formed in the decomposition are methane (CH4) and ethylene (C2H4); whereas ethane and propylene were ...

  2. Thermal decomposition of potassium bis-oxalatodiaqua-indate (III ...

    Indian Academy of Sciences (India)

    2] 3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate ... Bio-inorganic Chemistry Laboratories, School of Chemistry, Andhra University, Visakhapatnam 530 003, India ...

  3. Thermal decomposition of yttrium(III) hexanoate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Attique, Fahmida

    2015-01-01

    The thermal decomposition of yttrium(III) hexanoate (Y(C5H11CO2)3)·xH2O in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction at a laboratory Cu-tube source and in-situ experiments at a synchrotron radiation source as well as hot...

  4. Thermal decomposition of lanthanum(III) butyrate in argon atmosphere

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Xiao, Tang

    2013-01-01

    The thermal decomposition of La(C3H7CO2)3·xH2O (x≈0.82) was studied in argon during heating at 5K/min. After the loss of bound H2O, the anhydrous butyrate presents at 135°C a phase transition to a mesophase, which turns to an isotropic liquid at 180°C. The decomposition of the anhydrous butyrate ...

  5. The Products of the Thermal Decomposition of CH3CHO

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliou, AnGayle; Piech, Krzysztof M.; Zhang, Xu; Nimlos, Mark R.; Ahmed, Musahid; Golan, Amir; Kostko, Oleg; Osborn, David L.; Daily, John W.; Stanton, John F.; Ellison, G. Barney

    2011-04-06

    We have used a heated 2 cm x 1 mm SiC microtubular (mu tubular) reactor to decompose acetaldehyde: CH3CHO + DELTA --> products. Thermal decomposition is followed at pressures of 75 - 150 Torr and at temperatures up to 1700 K, conditions that correspond to residence times of roughly 50 - 100 mu sec in the mu tubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: VUV photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH3CHO, we have studied three isotopologues, CH3CDO, CD3CHO, and CD3CDO. We have identified the thermal decomposition products CH3(PIMS), CO (IR, PIMS), H (PIMS), H2 (PIMS), CH2CO (IR, PIMS), CH2=CHOH (IR, PIMS), H2O (IR, PIMS), and HC=CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH3CHO: Radical decomposition: CH3CHO + DELTA --> CH3 + [HCO] --> CH3 + H + CO Elimination: CH3CHO + DELTA --> H2 + CH2=C=O. Isomerization/elimination: CH3CHO + DELTA --> [CH2=CH-OH] --> HC=CH + H2O. Both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH2=C:, as an intermediate in the decomposition of vinyl alchohol: CH2=CH-OH + DELTA --> [CH2=C:] + H2O --> HC=CH + H2O.

  6. SIMULATION OF THERMAL DECOMPOSITION OF MINERAL INSULATING OIL

    Directory of Open Access Journals (Sweden)

    V. G. M. Cruz

    2015-09-01

    Full Text Available AbstractDissolved gas analysis (DGA has been applied for decades as the main predictive maintenance technique for diagnosing incipient faults in power transformers since the decomposition of the mineral insulating oil (MIO produces gases that remain dissolved in the liquid phase. Nevertheless, the most known diagnostic methods are based on findings of simplified thermodynamic and compositional models for the thermal decomposition of MIO, in addition to empirical data. The simulation results obtained from these models do not satisfactorily reproduce the empirical data. This paper proposes a flexible thermodynamic model enhanced with a kinetic approach and selects, among four compositional models, the one offering the best performance for the simulation of thermal decomposition of MIO. The simulation results obtained from the proposed model showed better adequacy to reported data than the results obtained from the classical models. The proposed models may be applied in the development of a phenomenologically-based diagnostic method.

  7. Thermal Decomposition Chemistry of Amine Borane (U)

    Energy Technology Data Exchange (ETDEWEB)

    Stowe, A. C.; Feigerle, J.; Smyrl, N. R.; Morrell, J. S.

    2010-01-29

    The conclusions of this presentation are: (1) Amine boranes potentially can be used as a vehicular hydrogen storage material. (2) Purity of the hydrogen stream is critical for use with a fuel cell. Pure H{sub 2} can be provided by carefully conditioning the fuel (encapsulation, drying, heating rate, impurities). (3) Thermodynamics and kinetics can be controlled by conditioning as well. (4) Regeneration of the spent amine borane fuel is still the greatest challenge to its potential use. (5) Addition of hydrocarbon-substituted amine boranes alter the chemistry dramatically. (6) Decomposition of the substituted amine borane mixed system favors reaction products that are more potentially easier to regenerate the hydrogenated fuel. (7) t-butylamine borane is not the best substituted amine borane to use since it releases isobutane; however, formation of CNBH{sub x} products does occur.

  8. A convenient thermal decomposition-co-reduction synthesis of ...

    Indian Academy of Sciences (India)

    ... Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 28; Issue 5. A convenient thermal decomposition-co-reduction synthesis of nanocrystalline tungsten disilicide. Jianhua Ma Yihong Du Yitai Qian. Nanomaterials Volume 28 Issue 5 August 2005 pp 511-513 ...

  9. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    but rely on the concentration of hydrogen. The model ... first-order rate law. Lehmhus and Rausch (2004) have annealed TiH2 pow- der in air and argon. In argon, the powder does not develop a surface layer and as a result, a small amount of hydro- gen is lost ... rate effect on the thermal decomposition behaviour of TiH2.

  10. alumina phase transformation from thermal decomposition

    African Journals Online (AJOL)

    HOD

    . It was found to be stable at higher ... thermal stability of the gamma alumina phase gives it good advantage to be used for high temperature applications, such as support for catalyst ..... owing to the low intensity counts as well as broad peaks.

  11. Thermal decomposition of hydroxylamine: Isoperibolic calorimetric measurements at different conditions

    Energy Technology Data Exchange (ETDEWEB)

    Adamopoulou, Theodora [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Papadaki, Maria I., E-mail: mpapadak@cc.uoi.gr [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Kounalakis, Manolis [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Vazquez-Carreto, Victor; Pineda-Solano, Alba [Mary Kay O’Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States); Wang, Qingsheng [Department of Fire Protection and Safety and Department of Chemical Engineering, Oklahoma State University, 494 Cordell South, Stillwater, OK 74078 (United States); Mannan, M.Sam [Mary Kay O’Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States)

    2013-06-15

    Highlights: • Hydroxylamine thermal decomposition enthalpy was measured using larger quantities. • The rate at which heat is evolved depends on hydroxylamine concentration. • Decomposition heat is strongly affected by the conditions and the selected baseline. • The need for enthalpy measurements using a larger reactant mass is pinpointed. • Hydroxylamine decomposition in the presence of argon is much faster than in air. -- Abstract: Thermal decomposition of hydroxylamine, NH{sub 2}OH, was responsible for two serious accidents. However, its reactive behavior and the synergy of factors affecting its decomposition are not being understood. In this work, the global enthalpy of hydroxylamine decomposition has been measured in the temperature range of 130–150 °C employing isoperibolic calorimetry. Measurements were performed in a metal reactor, employing 30–80 ml solutions containing 1.4–20 g of pure hydroxylamine (2.8–40 g of the supplied reagent). The measurements showed that increased concentration or temperature, results in higher global enthalpies of reaction per unit mass of reactant. At 150 °C, specific enthalpies as high as 8 kJ per gram of hydroxylamine were measured, although in general they were in the range of 3−5 kJ g{sup −1}. The accurate measurement of the generated heat was proven to be a cumbersome task as (a) it is difficult to identify the end of decomposition, which after a fast initial stage, proceeds very slowly, especially at lower temperatures and (b) the environment of gases affects the reaction rate.

  12. The products of the thermal decomposition of CH3CHO.

    Science.gov (United States)

    Vasiliou, AnGayle; Piech, Krzysztof M; Zhang, Xu; Nimlos, Mark R; Ahmed, Musahid; Golan, Amir; Kostko, Oleg; Osborn, David L; Daily, John W; Stanton, John F; Ellison, G Barney

    2011-07-07

    We have used a heated 2 cm × 1 mm SiC microtubular (μtubular) reactor to decompose acetaldehyde: CH(3)CHO + Δ → products. Thermal decomposition is followed at pressures of 75-150 Torr and at temperatures up to 1675 K, conditions that correspond to residence times of roughly 50-100 μs in the μtubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: vacuum ultraviolet photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH(3)CHO, we have studied three isotopologues, CH(3)CDO, CD(3)CHO, and CD(3)CDO. We have identified the thermal decomposition products CH(3) (PIMS), CO (IR, PIMS), H (PIMS), H(2) (PIMS), CH(2)CO (IR, PIMS), CH(2)=CHOH (IR, PIMS), H(2)O (IR, PIMS), and HC≡CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH(3)CHO; namely, radical decomposition: CH(3)CHO + Δ → CH(3) + [HCO] → CH(3) + H + CO; elimination: CH(3)CHO + Δ → H(2) + CH(2)=C=O; isomerization∕elimination: CH(3)CHO + Δ → [CH(2)=CH-OH] → HC≡CH + H(2)O. An interesting result is that both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH(2)=C:, as an intermediate in the decomposition of vinyl alcohol: CH(2)=CH-OH + Δ → [CH(2)=C:] + H(2)O → HC≡CH + H(2)O.

  13. Resolving Some Paradoxes in the Thermal Decomposition Mechanism of Acetaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Sivaramakrishnan, Raghu; Michael, Joe V.; Harding, Lawrence B.; Klippenstein, Stephen J.

    2015-07-16

    The mechanism for the thermal decomposition of acetaldehyde has been revisited with an analysis of literature kinetics experiments using theoretical kinetics. The present modeling study was motivated by recent observations, with very sensitive diagnostics, of some unexpected products in high temperature micro-tubular reactor experiments on the thermal decomposition of CH3CHO and its deuterated analogs, CH3CDO, CD3CHO, and CD3CDO. The observations of these products prompted the authors of these studies to suggest that the enol tautomer, CH2CHOH (vinyl alcohol), is a primary intermediate in the thermal decomposition of acetaldehyde. The present modeling efforts on acetaldehyde decomposition incorporate a master equation re-analysis of the CH3CHO potential energy surface (PES). The lowest energy process on this PES is an isomerization of CH3CHO to CH2CHOH. However, the subsequent product channels for CH2CHOH are substantially higher in energy, and the only unimolecular process that can be thermally accessed is a re-isomerization to CH3CHO. The incorporation of these new theoretical kinetics predictions into models for selected literature experiments on CH3CHO thermal decomposition confirms our earlier experiment and theory based conclusions that the dominant decomposition process in CH3CHO at high temperatures is C-C bond fission with a minor contribution (~10-20%) from the roaming mechanism to form CH4 and CO. The present modeling efforts also incorporate a master-equation analysis of the H + CH2CHOH potential energy surface. This bimolecular reaction is the primary mechanism for removal of CH2CHOH, which can accumulate to minor amounts at high temperatures, T > 1000 K, in most lab-scale experiments that use large initial concentrations of CH3CHO. Our modeling efforts indicate that the observation of ketene, water and acetylene in the recent micro-tubular experiments are primarily due to bimolecular reactions of CH3CHO and CH2CHOH with H-atoms, and have no bearing on

  14. Mechanism of the Thermal Decomposition of Ethanethiol and Dimethylsulfide

    Science.gov (United States)

    Melhado, William Francis; Whitman, Jared Connor; Kong, Jessica; Anderson, Daniel Easton; Vasiliou, AnGayle (AJ)

    2016-06-01

    Combustion of organosulfur contaminants in petroleum-based fuels and biofuels produces sulfur oxides (SO_x). These pollutants are highly regulated by the EPA because they have been linked to poor respiratory health and negative environmental impacts. Therefore much effort has been made to remove sulfur compounds in petroleum-based fuels and biofuels. Currently desulfurization methods used in the fuel industry are costly and inefficient. Research of the thermal decomposition mechanisms of organosulfur species can be implemented via engineering simulations to modify existing refining technologies to design more efficient sulfur removal processes. We have used a resistively-heated SiC tubular reactor to study the thermal decomposition of ethanethiol (CH_3CH_2SH) and dimethylsulfide (CH_3SCH_3). The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectroscopy and infrared spectroscopy. The thermal cracking products for CH_3CH_2SH are CH_2CH_2, SH, and H_2S and the thermal cracking products from CH_3SCH_3 are CH_3S, CH_2S, and CH_3.

  15. Pollutant content in marine debris and characterization by thermal decomposition.

    Science.gov (United States)

    Iñiguez, M E; Conesa, J A; Fullana, A

    2017-04-15

    Marine debris (MDs) produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (plastics), leading to a gradual accumulation in the coastal and marine environment. Characterization of the MDs has been done in terms of their pollutant content: PAHs, ClBzs, ClPhs, BrPhs, PCDD/Fs and PCBs. The results show that MDs is not a very contaminated waste. Also, thermal decomposition of MDs materials has been studied in a thermobalance at different atmospheres and heating rates. Below 400-500K, the atmosphere does not affect the thermal degradation of the mentioned waste. However, at temperatures between 500 and 800K the presence of oxygen accelerates the decomposition. Also, a kinetic model is proposed for the combustion of the MDs, and the decomposition is compared with that of their main constituents, i.e., polyethylene (PE), polystyrene (PS), polypropylene (PP), nylon and polyethylene-terephthalate (PET). Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Kinetics of lithium peroxide monohydrate thermal decomposition

    Science.gov (United States)

    Nefedov, Roman; Posternak, Nikolay; Ferapontov, Yuriy

    2017-11-01

    Topochemical dehydration of lithium peroxide was studied to determine kinetic parameters at the range of temperatures from 90°C to 147°C in non-isothermal conditions by derivatographic method. The study was conducted to select optimal conditions of lithium peroxide synthesis in dehydration reaction of triple LiOH-H2O2-H2O system in ultra-high frequency radiation field. Conditions of dehydration reaction were caused by the thermal conductivity of LiOH -H2O2-H2O system. It is determined that dehydration process runs close to the first order reaction (n=0.85±0.03). The activation energy and pre-exponential factor values were found as Eak = 86.0 ± 0.8 kJ/mol, k0 = (2.19 ± 0.16) .1011 min-1, correspondingly. It is supposed that there is a similarity between the dehydration mechanism of lithium peroxide monohydrate and peroxide hydrates of alkaline-earth metals (calcium, barium and strontium).

  17. Thermal decomposition of dolomite under CO2-air atmosphere

    Science.gov (United States)

    Subagjo, Wulandari, Winny; Adinata, Pratitis Mega; Fajrin, Anita

    2017-01-01

    This paper reports a study on thermal decomposition of dolomite under CO2-air. Calcination was carried out non-isothermally by using thermogravimetry analysis-differential scanning calorimetry (TGA-DSC) with a heating rate of 10°C/minute in an air atmosphere as well as 10 vol% CO2 and 90 vol% air atmosphere from 25 to 950°C. In addition, a thermodynamic modeling was also carried out to simulate dolomite calcination in different level of CO2-air atmosphere by using FactSage® 7.0. The the main constituents of typical dolomite from Gresik, East Java include MgCO3 (magnesite), CaCO3 (calcite), Ca(OH)2, CaO, MgO, and less than 1% of metal impurities. Based on the kinetics analysis from TGA results, it is found that non-isothermal dolomite calcination in 10 vol% CO2 atmosphere is occurred in a two-stage reaction; the first stage is the decomposition of magnesite at 650-740 °C with activation energy of 161.23 kJ/mol, and the second stage is the decomposition of calcite at 775-820 °C with activation energy of 162.46 kJ/mol. The magnesite decomposition is found to follow nucleation reaction mechanism of Avrami Eroveyef (A3), while calcite decomposition follows second order chemical reaction equation. Thermodynamic modeling supports these kinetic analyses. The results of this research give insight to the kinetics of dolomite decomposition in CO2-air atmosphere.

  18. Isoconversional Kinetic Study Of The Thermal Decomposition Of Sugarcane Straw For Thermal Conversion Processes.

    OpenAIRE

    Rueda-Ordóñez, Yesid Javier; Tannous, Katia

    2016-01-01

    The aim of this work was investigate the kinetics of the thermal decomposition reaction of sugarcane straw. The thermal decomposition experiments were conducted at four heating rates (1.25, 2.5, 5 and 10 degrees C/min) in a thermogravimetric analyzer using nitrogen as inert atmosphere. The kinetic analysis was carried out applying the isoconversional method of Friedman, and the activation energies obtained varied from 154.1 kJ/mol to 177.8 kJ/mol. The reaction model was determined through mas...

  19. Programming Enhancements for Low Temperature Thermal Decomposition Workstation

    Energy Technology Data Exchange (ETDEWEB)

    Igou, R.E.

    1998-10-01

    This report describes a new control-and-measurement system design for the Oak Ridge Y-12 Plant's Low Temperature Thermal Decomposition (LTTD) process. The new design addresses problems with system reliability stemming from equipment obsolescence and addresses specific functional improvements that plant production personnel have identified, as required. The new design will also support new measurement techniques, which the Y-12 Development Division has identified for future operations. The new techniques will function in concert with the original technique so that process data consistency is maintained.

  20. Thermal Plasma Decomposition Of Nickel And Cobalt Compounds

    Directory of Open Access Journals (Sweden)

    Woch M.

    2015-06-01

    Full Text Available The paper presents the study on manufacturing of nickel and cobalt powders by thermal plasma decomposition of the carbonates of these metals. It was shown the dependence of process parameters and grain size of initial powder on the composition of final product which was ether metal powder, collected in the container as well as the nanopowder with crystallite size of 70 - 90 nm, collected on the inner wall of the reaction chamber. The occurrence of metal oxides in the final products was confirmed and discussed.

  1. Thermal wet decomposition of Prussian Blue: implications for prebiotic chemistry.

    Science.gov (United States)

    Ruiz-Bermejo, Marta; Rogero, Celia; Menor-Salván, César; Osuna-Esteban, Susana; Martín-Gago, José Angel; Veintemillas-Verdaguer, Sabino

    2009-09-01

    The complex salt named Prussian Blue, Fe4[Fe(CN)6]3 x 15 H2O, can release cyanide at pH > 10. From the point of view of the origin of life, this fact is of interest, since the oligomers of HCN, formed in the presence of ammonium or amines, leads to a variety of biomolecules. In this work, for the first time, the thermal wet decomposition of Prussian Blue was studied. To establish the influence of temperature and reaction time on the ability of Prussian Blue to release cyanide and to subsequently generate other compounds, suspensions of Prussian Blue were heated at temperatures from room temperature to 150 degrees at pH 12 in NH3 environment for several days. The NH3 wet decomposition of Prussian Blue generated hematite, alpha-Fe2O3, the soluble complex salt (NH4)4[Fe(CN6)] x 1.5 H2O, and several organic compounds, the nature and yield of which depend on the experimental conditions. Urea, lactic acid, 5,5-dimethylhydantoin, and several amino acids and carboxylic acids were identified by their trimethylsilyl (TMS) derivatives. HCN, cyanogen (C2N2), and formamide (HCONH2) were detected in the gas phase by GC/MS analysis.

  2. Physicochemical Characterization and Thermal Decomposition of Garin Maiganga Coal

    Directory of Open Access Journals (Sweden)

    Nyakuma Bemgba Bevan

    2016-12-01

    Full Text Available The paper examined physicochemical and thermal characteristics of the newly discovered Garin Maiganga (GMG coal from Nigeria. The physicochemical characterization comprised of elemental, proximate, calorific value, and classification (rank analyses. Thermal analysis was examined using combined Thermogravimetric (TG and Derivative Thermogravimetric analyses (DTG. Hence, the coal was heated from 30°C to 1000°C at 20°C/min under inert conditions to examine its thermal degradation behaviour and temperature profile characteristics (TPC. The results indicated that the GMG coal fuel properties consist of low Ash, Nitrogen, and Sulphur content. Moisture content was > 5%, Volatile Matter > 50%, Fixed Carbon > 22%, and Heating Value (HHV 23.74 MJ/kg. Based on its fuel properties, the GMG coal can be classified as a Sub-Bituminous B, non-agglomerating low rank coal (LRC. The GMG coal TPCs – onset, peak, and offset temperatures – were 382.70°C, 454.60°C, and 527.80°C, respectively. The DTG profile revealed four (4 endothermic peaks corresponding to loss of moisture (drying, volatile matter (devolatization, and coke formation. The residual mass Rm was 50.16%, which indicates that higher temperatures above 1000°C are required for the complete pyrolytic decomposition of the GMG coal. In conclusion, the results indicate that the GMG coal is potentially suitable for future utilization in electric power generation and the manufacture of cement and steel.

  3. A High Temperature Kinetic Study for the Thermal Unimolecular Decomposition of Diethyl Carbonate

    KAUST Repository

    Alabbad, Mohammed

    2017-07-08

    Thermal unimolecular decomposition of diethyl carbonate (DEC) was investigated in a shock tube by measuring ethylene concentration with a CO2 gas laser over 900 - 1200 K and 1.2 – 2.8 bar. Rate coefficients were extracted using a simple kinetic scheme comprising of thermal decomposition of DEC as initial step followed by rapid thermal decomposition of the intermediate ethyl-hydrogen-carbonate. Our results were further analysed using ab initio and master equation calculations to obtain pressure- and temperature- dependence of rate coefficients. Similar to alkyl esters, unimolecular decomposition of DEC is found to undergo six-center retro-ene elimination of ethylene in a concerted manner.

  4. Effect of urea additive on the thermal decomposition kinetics of flame retardant greige cotton nonwoven fabric

    Science.gov (United States)

    Sunghyun Nam; Brian D. Condon; Robert H. White; Qi Zhao; Fei Yao; Michael Santiago Cintrón

    2012-01-01

    Urea is well known to have a synergistic action with phosphorus-based flame retardants (FRs) in enhancing the FR performance of cellulosic materials, but the effect of urea on the thermal decomposition kinetics has not been thoroughly studied. In this study, the activation energy (Ea) for the thermal decomposition of greige...

  5. The response of the HMX-based material PBXN-9 to thermal insults: thermal decomposition kinetics and morphological changes

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E A; Hsu, P C; Springer, H K; DeHaven, M R; Tan, N; Turner, H C

    2010-12-10

    PBXN-9, an HMX-formulation, is thermally damaged and thermally decomposed in order to determine the morphological changes and decomposition kinetics that occur in the material after mild to moderate heating. The material and its constituents were decomposed using standard thermal analysis techniques (DSC and TGA) and the decomposition kinetics are reported using different kinetic models. Pressed parts and prill were thermally damaged, i.e. heated to temperatures that resulted in material changes but did not result in significant decomposition or explosion, and analyzed. In general, the thermally damaged samples showed a significant increase in porosity and decrease in density and a small amount of weight loss. These PBXN-9 samples appear to sustain more thermal damage than similar HMX-Viton A formulations and the most likely reasons are the decomposition/evaporation of a volatile plasticizer and a polymorphic transition of the HMX from {beta} to {delta} phase.

  6. Thermal decomposition of fullerene nanowhiskers protected by amorphous carbon mask

    Science.gov (United States)

    Guo, Hongxuan; Wang, Chengxiang; Miyazawa, Kun'Ichi; Wang, Hongxin; Masuda, Hideki; Fujita, Daisuke

    2016-12-01

    Fullerene nanostructures are well known for their unique morphology, physical and mechanical properties. The thermal stability of fullerene nanostructures, such as their sublimation at high temperature is also very important for studying their structures and applications. In this work, We observed fullerene nanowhiskers (FNWs) in situ with scanning helium ion microscopy (HIM) at elevated temperatures. The FNWs exhibited different stabilities with different thermal histories during the observation. The pristine FNWs were decomposed at the temperatures higher than 300 °C in a vacuum environment. Other FNWs were protected from decomposition with an amorphous carbon (aC) film deposited on the surface. Based on high spacial resolution, aC film with periodic structure was deposited by helium ion beam induced deposition (IBID) on the surface of FNWs. Annealed at the high temperature, the fullerene molecules were selectively sublimated from the FNWs. The periodic structure was formed on the surface of FNWs and observed by HIM. Monte Carlo simulation and Raman characterization proved that the morphology of the FNWs was changed by helium IBID at high temperature. This work provides a new method of fabricating artificial structure on the surface of FNWs with periodic aC film as a mask.

  7. Numerical analysis of thermal decomposition for RDX, TNT, and Composition B

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Shin Hyuk; Nyande, Baggie W. [Department of Chemical Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 305-719 (Korea, Republic of); Kim, Hyoun Soo; Park, Jung Su [Agency for Defence Development, 462 Jochiwon-gil, Yuseong-gu, Daejeon 305-150 (Korea, Republic of); Lee, Woo Jin [Hanwha corporation, 117 Yeosusandan 3-ro, Yeosu-si, Jeollanam-do (Korea, Republic of); Oh, Min, E-mail: minoh@hanbat.ac.kr [Department of Chemical Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 305-719 (Korea, Republic of)

    2016-05-05

    Highlights: • Reaction mechanism of thermal decomposition of military explosives is investigated. • Mathematical modeling of thermal decomposition are executed. • Commercial scale reactor is employed for demilitarization of waste explosives. • Dynamic response of thermal decomposition is examined in a reactor. - Abstract: Demilitarization of waste explosives on a commercial scale has become an important issue in many countries, and this has created a need for research in this area. TNT, RDX and Composition B have been used as military explosives, and they are very sensitive to thermal shock. For the safe waste treatment of these high-energy and highly sensitive explosives, the most plausible candidate suggested has been thermal decomposition in a rotary kiln. This research examines the safe treatment of waste TNT, RDX and Composition B in a rotary kiln type incinerator with regard to suitable operating conditions. Thermal decomposition in this study includes melting, 3 condensed phase reactions in the liquid phase and 263 gas phase reactions. Rigorous mathematical modeling and dynamic simulation for thermal decomposition were carried out for analysis of dynamic behavior in the reactor. The results showed time transient changes of the temperature, components and mass of the explosives and comparisons were made for the 3 explosives. It was concluded that waste explosives subject to heat supplied by hot air at 523.15 K were incinerated safely without any thermal detonation.

  8. Synthesis, Optical Characterization, and Thermal Decomposition of Complexes Based on Biuret Ligand

    National Research Council Canada - National Science Library

    Wang, Mei-Ling; Zhong, Guo-Qing; Chen, Ling

    2016-01-01

    .... The nickel and manganese ions were all hexacoordinated. The thermal decomposition processes of the complexes under air included the loss of water molecule, the pyrolysis of ligands, and the decomposition of inorganic salts, and the final residues were nickel oxide and manganese oxide, respectively.

  9. Kinetics of the thermal decomposition of pine needles

    Directory of Open Access Journals (Sweden)

    Dhaundiyal Alok

    2015-12-01

    Full Text Available A kinetic study of the pyrolysis process of pine needles was examined using a thermogravimetric analyser. The weight loss was measured in nitrogen atmosphere at a purge flow rate of 100 ml/min. The samples were heated over a range of temperature of 19°C–600°C with a heating rate of 10°C/min. The results obtained from the thermal decomposition process indicate that there are three main stages: dehydration, active and passive pyrolysis. The kinetic parameters for the different samples, such as activation energy and pre-exponential factor, are obtained by the shrinking core model (reaction-controlled regime, the model-free, and the first-order model. Experimental results showed that the shrinking model is in good agreement and can be successfully used to understand degradation mechanism of loose biomass. The result obtained from the reaction-controlled regime represented actual values of kinetic parameters which are the same for the whole pyrolysis process; whereas the model-free method presented apparent values of kinetic parameters, as they are dependent on the unknown function ϕ(C, on the sum of the parameters of the physical processes, and on the chemical reactions that happen simultaneously during pyrolysis. Experimental results showed that values of kinetic constant from the first-order model and the SCM are in good agreement and can be successfully used to understand the behaviour of loose biomass (pine needles in the presence of inert atmosphere. Using TGA results, the simulating pyrolysis can be done, with the help of computer software, to achieve a comprehensive detail of the devolatilization process of different types of biomasses.

  10. SYNTHESIS AND CHARACTERIZATION OF METALLIC COPPER NANOPARTICLES VIA THERMAL DECOMPOSITION METHOD

    OpenAIRE

    A. Dinesh Karthik; Dr. K. Geetha

    2017-01-01

    Copper (II) fumarate was used as a precursor to prepare metallic copper nanoparticles by thermal decomposition. Synthesis of inorganic nanoparticles by thermal decomposition is one of the methods to produce stable nanodisperse suspensions with the ability of self assembly. Copper (II) fumarate precursor was treated with oleylamine which is used as both the medium and the Stabilizing reagent. The precursor and copper nanoparticles were characterized by UV-Vis Spectroscopy, FT - IR, XRD, CV, AF...

  11. Thermal decomposition of ethylenediaminetetraacetic acid in the presence of 1,2-phenylenediamine and hydrochloric acid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingwen [Yancheng Institute of Technology, Yancheng (China); Gao, Jinhao [Nanjing Univ., Nanjing (China). Coordination Chemistry Institute. State Key Lab. of Coordination Chemistry; Wang, Xiaoyong [Nanjing Univ., Nanjing (China). School of Life Science. State Key Lab. of Pharmaceutical Biotechnology]. E-mail: boxwxy@nju.edu.cn

    2006-09-15

    Based on the reaction products of ethylenediaminetetraacetic acid (EDTA) with 1,2- phenylenediamine (o-PDA), a novel thermal decomposition pathway of EDTA is proposed. The strong acidic medium and the presence of o-PDA facilitate the decomposition of EDTA as evidenced by the relatively lower reaction temperature. In addition to the steps described in literatures, rearrangement process is involved in the decomposition reaction. The rearranged intermediates condense with o-PDA, forming an unexpected biologically active compound 2,2,4- trimethyl-3H-5-hydro-1,5-benzodiazepine, thus provides the possibility to explore an alternative decomposition mechanism for this widely used chelator. (author)

  12. Thermal Decomposition of RDX from Reactive Molecular Dynamics

    National Research Council Canada - National Science Library

    Strachan, Alejandro; Kober, Edward M; van Duin, Adri C; Oxgaard, Jonas; Goddard, III, William A

    2005-01-01

    ...] at various temperatures and densities. We find that the time evolution of the potential energy can be described reasonably well with a single exponential function from which we obtain an overall characteristic time of decomposition...

  13. The correlation between elongation at break and thermal decomposition of aged EPDM cable polymer

    Science.gov (United States)

    Šarac, T.; Devaux, J.; Quiévy, N.; Gusarov, A.; Konstantinović, M. J.

    2017-03-01

    The effect of simultaneous thermal and gamma irradiation ageing on the mechanical and physicochemical properties of industrial EPDM was investigated. Accelerated ageing, covering a wide range of dose rates, doses and temperatures, was preformed in stagnant air on EPDM polymer samples extracted from the cables in use in the Belgian nuclear power plants. The mechanical properties, ultimate tensile stress and elongation at break, are found to exhibit the strong dependence on the dose, ageing temperature and dose rate. The thermal decomposition of aged polymer is observed to be the dose dependent when thermogravimetry test is performed under air atmosphere. No dose dependence is observed when thermal decomposition is performed under nitrogen atmosphere. The thermal decomposition rates are found to fully mimic the reduction of elongation at break for all dose rates and ageing temperatures. This effect is argued to be the result of thermal and radiation mediated oxidation degradation process.

  14. The thermal decomposition behavior of ammonium perchlorate and of an ammonium-perchlorate-based composite propellant

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.; Minier, L.

    1998-03-24

    The thermal decomposition of ammonium perchlorate (AP) and ammonium-perchlorate-based composite propellants is studied using the simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) technique. The main objective of the present work is to evaluate whether the STMBMS can provide new data on these materials that will have sufficient detail on the reaction mechanisms and associated reaction kinetics to permit creation of a detailed model of the thermal decomposition process. Such a model is a necessary ingredient to engineering models of ignition and slow-cookoff for these AP-based composite propellants. Results show that the decomposition of pure AP is controlled by two processes. One occurs at lower temperatures (240 to 270 C), produces mainly H{sub 2}O, O{sub 2}, Cl{sub 2}, N{sub 2}O and HCl, and is shown to occur in the solid phase within the AP particles. 200{micro} diameter AP particles undergo 25% decomposition in the solid phase, whereas 20{micro} diameter AP particles undergo only 13% decomposition. The second process is dissociative sublimation of AP to NH{sub 3} + HClO{sub 4} followed by the decomposition of, and reaction between, these two products in the gas phase. The dissociative sublimation process occurs over the entire temperature range of AP decomposition, but only becomes dominant at temperatures above those for the solid-phase decomposition. AP-based composite propellants are used extensively in both small tactical rocket motors and large strategic rocket systems.

  15. Thermal Decomposition Model Development of EN-7 and EN-8 Polyurethane Elastomers.

    Energy Technology Data Exchange (ETDEWEB)

    Keedy, Ryan Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harrison, Kale Warren [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cordaro, Joseph Gabriel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    Thermogravimetric analysis - gas chromatography/mass spectrometry (TGA- GC/MS) experiments were performed on EN-7 and EN-8, analyzed, and reported in [1] . This SAND report derives and describes pyrolytic thermal decomposition models for use in predicting the responses of EN-7 and EN-8 in an abnormal thermal environment.

  16. Thermal decomposition of AP/HTPB propellants in presence of Zn nanoalloys

    Science.gov (United States)

    Chaturvedi, Shalini; Dave, Pragnesh N.; Patel, Nikul N.

    2015-01-01

    Composite solid propellants were prepared with and without nanoalloys (Zn-Cu, Zn-Ni, Zn-Fe), where nanoalloys are used as catalyst. Catalytic properties of these nanomaterials measured on ammonium perchlorate/hydroxyl-terminated polybutadiene propellant by thermogravimetric analysis and differential thermal analysis. Both experimental results show enhancement in the thermal decomposition of propellants in presence of nanoalloys. In differential thermal analysis method, experiments had done at three heating rates, β1 = 5°, β2 = 10°, β3 = 15° per minute. Calculation of activation energy of high temperature decomposition step was done by using following Kissinger equation. Zn-Cu was found to be the best.

  17. Thermal decomposition of nano-enabled thermoplastics: Possible environmental health and safety implications

    Energy Technology Data Exchange (ETDEWEB)

    Sotiriou, Georgios A.; Singh, Dilpreet; Zhang, Fang [Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Ave., Boston, MA 02115 (United States); Chalbot, Marie-Cecile G. [Department of Environmental and Occupational Health, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205 (United States); Spielman-Sun, Eleanor [Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Hoering, Lutz [BASF SE, Material Physics, 67056 Ludwigshafen (Germany); Kavouras, Ilias G. [Department of Environmental and Occupational Health, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205 (United States); Lowry, Gregory V. [Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Wohlleben, Wendel [Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Ave., Boston, MA 02115 (United States); BASF SE, Material Physics, 67056 Ludwigshafen (Germany); Demokritou, Philip, E-mail: pdemokri@hsph.harvard.edu [Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Ave., Boston, MA 02115 (United States)

    2016-03-15

    Highlights: • Nano-enabled products might reach their end-of-life by thermal decomposition. • Thermal decomposition provides two by-products: released aerosol and residual ash. • Is there any nanofiller release in byproducts? • Risk assessment of potential environmental health implications. - Abstract: Nano-enabled products (NEPs) are currently part of our life prompting for detailed investigation of potential nano-release across their life-cycle. Particularly interesting is their end-of-life thermal decomposition scenario. Here, we examine the thermal decomposition of widely used NEPs, namely thermoplastic nanocomposites, and assess the properties of the byproducts (released aerosol and residual ash) and possible environmental health and safety implications. We focus on establishing a fundamental understanding on the effect of thermal decomposition parameters, such as polymer matrix, nanofiller properties, decomposition temperature, on the properties of byproducts using a recently-developed lab-based experimental integrated platform. Our results indicate that thermoplastic polymer matrix strongly influences size and morphology of released aerosol, while there was minimal but detectable nano-release, especially when inorganic nanofillers were used. The chemical composition of the released aerosol was found not to be strongly influenced by the presence of nanofiller at least for the low, industry-relevant loadings assessed here. Furthermore, the morphology and composition of residual ash was found to be strongly influenced by the presence of nanofiller. The findings presented here on thermal decomposition/incineration of NEPs raise important questions and concerns regarding the potential fate and transport of released engineered nanomaterials in environmental media and potential environmental health and safety implications.

  18. Kinetics of the thermal decomposition of tetramethylsilane behind ...

    Indian Academy of Sciences (India)

    equal concentrations via reaction 1. It was further con- firmed that, 1,3-butadiene does not decompose in the investigated range of the temperatures, by carrying out its decomposition independently. Skinner et al.,37 and. Hidaka et al.,38 also have reported that 1,3-butadiene does not decompose in this temperature range.

  19. The kinetics and mechanism of induced thermal decomposition of ...

    Indian Academy of Sciences (India)

    The kinetics of induced decomposition of potassium peroxomonosulphate (PMS) by the phase transfer catalysts (PTC), viz. tetrabutylammonium chloride [TBAC] and tetrabutylphosphonium chloride [TBPC] have been investigated. The effect of [PMS], [PTC], ionic strength of the medium and temperature on the rate of ...

  20. The kinetics and mechanism of induced thermal decomposition of ...

    Indian Academy of Sciences (India)

    Unknown

    only in organic chemistry 1 but also in inorganic chemistry 2, analytical application 3, in electrochemistry 4–7, photochemistry 8,9 and in polymer chemistry 10–15. The spontaneous decomposition of potassium peroxomonosulphate (PMS) in aqueous solution suggests that free radicals are not formed. The kinetics and ...

  1. Lignin derivatives formation in catalysed thermal decomposition of ...

    African Journals Online (AJOL)

    Decomposition of elephant grass (Panicum maxima) lignocellulose was carried out with Pd and Ni/Pt-doped alumina as catalysts; chromic oxide was also used in some cases. For systems that contained no chromic oxide, formation of gaseous and volatile liquid products was highest for Ni/Pt, intermediate for Pd/λ- and least ...

  2. Thermal decomposition of natural polysaccharides: Chitin and chitosan

    Directory of Open Access Journals (Sweden)

    Kuchina Yu.A.

    2015-03-01

    Full Text Available The results of the thermal analysis of shrimp’s chitin and chitosan have been presented (samples of polysaccharide differed by the deacetylation degree have been studied. The thermal analysis has been carried out by differential thermogravimetry and differential scanning calorimetry. Activation energy of process of chitin and chitosan thermal destruction has been calculated

  3. Thermal decomposition and kinetics of 2,4-dinitroimidazole: An insensitive high explosive

    Energy Technology Data Exchange (ETDEWEB)

    Anniyappan, M., E-mail: anniorganic@rediffmail.com; Sonawane, S.H.; Pawar, S.J.; Sikder, A.K.

    2015-08-20

    Highlights: • Pure 2,4-dinitroimidazole was prepared by re-crystallization from hot methanol. • A detailed thermal analysis of 2,4-DNI by DSC, TGA, GC–MS and ignition temperature. • Activation energy was calculated for thermal decomposition of 2,4-DNI • Effect of polymeric binder on thermal decomposition of 2,4-DNI were also studied. • Decomposition mechanisms of 2,4-DNI based on EI mass spectra were also described. - Abstract: 2,4-Dinitroimidazole (2,4-DNI) is a novel energetic material with much less sensitive and potential for use as a propellant/insensitive munition (IM) formulations. 2,4-DNI possess high thermal stability and less sensitivity as compared to RDX and HMX which are high explosives extensively used at present. This paper reports a detailed thermal study of 2,4-DNI using various instrumental techniques. The activation energy (E = 205 ± 15 kJ/mol) was calculated from thermal decomposition of 2,4-DNI using DSC at different heating rate. The ignition temperature of pure 2,4-DNI was measured and showed at 285 °C. The TGA experiments demonstrate that 2,4-DNI decomposes in three steps with 92% total weight lose. Moreover, the effect of thermal energy on decomposition of 2,4-DNI in presence of polymeric binders like GAP and HTPB were investigated. Further, decomposition mechanisms of 2,4-DNI based on Electron Impact mass spectra analysis were also reported along with its explosive properties.

  4. Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret

    Science.gov (United States)

    Sun, Hongyan; Vaghjiani, Ghanshyam L.

    2015-05-01

    Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH2 group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C2v symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice-Ramsperger-Kassel-Marcus/multi-well master equation simulations, the results of which reveal the formation

  5. Ab Initio Kinetics and Thermal Decomposition Mechanism of Mononitrobiuret and 1,5- Dinitrobiuret

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongyan; Vaghjiani, Ghanshyam G.

    2015-05-26

    Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH2 group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C2v symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice–Ramsperger–Kassel–Marcus/multi-well master equation simulations, the results of which reveal the

  6. Kinetic analysis of overlapping multistep thermal decomposition comprising exothermic and endothermic processes: thermolysis of ammonium dinitramide.

    Science.gov (United States)

    Muravyev, Nikita V; Koga, Nobuyoshi; Meerov, Dmitry B; Pivkina, Alla N

    2017-01-25

    This study focused on kinetic modeling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the practical kinetic analysis of the experimental kinetic curves for the thermal decomposition of molten ammonium dinitramide (ADN). It is known that the thermal decomposition of ADN occurs as a consecutive two step mass-loss process comprising the decomposition of ADN and subsequent evaporation/decomposition of in situ generated ammonium nitrate. These reaction steps provide exothermic and endothermic contributions, respectively, to the overall thermal effect. The overall reaction process was deconvoluted into two reaction steps using simultaneously recorded thermogravimetry and differential scanning calorimetry (TG-DSC) curves by considering the different physical meanings of the kinetic data derived from TG and DSC by P value analysis. The kinetic data thus separated into exothermic and endothermic reaction steps were kinetically characterized using kinetic computation methods including isoconversional method, combined kinetic analysis, and master plot method. The overall kinetic behavior was reproduced as the sum of the kinetic equations for each reaction step considering the contributions to the rate data derived from TG and DSC. During reproduction of the kinetic behavior, the kinetic parameters and contributions of each reaction step were optimized using kinetic deconvolution analysis. As a result, the thermal decomposition of ADN was successfully modeled as partially overlapping exothermic and endothermic reaction steps. The logic of the kinetic modeling was critically examined, and the practical usefulness of phenomenological modeling for the thermal decomposition of ADN was illustrated to demonstrate the validity of the methodology and its applicability to similar complex reaction processes.

  7. Comparative evaluation of thermal decomposition behavior and thermal stability of powdered ammonium nitrate under different atmosphere conditions.

    Science.gov (United States)

    Yang, Man; Chen, Xianfeng; Wang, Yujie; Yuan, Bihe; Niu, Yi; Zhang, Ying; Liao, Ruoyu; Zhang, Zumin

    2017-09-05

    In order to analyze the thermal decomposition characteristics of ammonium nitrate (AN), its thermal behavior and stability under different conditions are studied, including different atmospheres, heating rates and gas flow rates. The evolved decomposition gases of AN in air and nitrogen are analyzed with a quadrupole mass spectrometer. Thermal stability of AN at different heating rates and gas flow rates are studied by differential scanning calorimetry, thermogravimetric analysis, paired comparison method and safety parameter evaluation. Experimental results show that the major evolved decomposition gases in air are H2O, NH3, N2O, NO, NO2 and HNO3, while in nitrogen, H2O, NH3, NO and HNO3 are major components. Compared with nitrogen atmosphere, lower initial and end temperatures, higher heat flux and broader reaction temperature range are obtained in air. Meanwhile, higher air gas flow rate tends to achieve lower reaction temperature and to reduce thermal stability of AN. Self-accelerating decomposition temperature of AN in air is much lower than that in nitrogen. It is considered that thermostability of AN is influenced by atmosphere, heating rate and gas flow rate, thus changes of boundary conditions will influence its thermostability, which is helpful to its safe production, storage, transportation and utilization. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The Effect of Water Vapor on the Thermal Decomposition of Pyrite in N2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Nesrin BOYABAT

    2009-03-01

    Full Text Available In this study, the effect of water vapor on the thermal decomposition of pyrite mineral in nitrogen atmosphere has been investigated in a horizontal tube furnace. Temperature, time and water vapor concentration were used as experimental parameters. According to the data obtained at nitrogen/ water vapor environment, it was observed that the water vapor on the decomposition of pyrite increased the decomposition rate. The decomposition reaction is well represented by the "shrinking core" model and can be divided into two regions with different rate controlling step. The rate controlling steps were determined from the heat transfer through the gas film for the low conversions, while it was determined from the mass transfer through product ash layer for the high conversions. The activation energies of this gas and ash film mechanisms were found to be 77 and 81 kJ/mol-1, respectively.

  9. Quantitative structure—property relationship for thermal decomposition temperature of ionic liquids

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Sattari, Mehdi; Ilani-Kashkouli, Poorandokht

    2012-01-01

    In this study, a wide literature survey has been conducted to gather an extensive set of thermal decomposition temperature (Td) data for ionic liquids (ILs). A data set consisting of Td data for 586 ILs was collated from 71 different literature sources. Using this data set, a reliable quantitative...

  10. Catalytic non-thermal plasma reactor for the decomposition of a ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 3. Catalytic non-thermal plasma reactor for the decomposition of a mixture of volatile organic compounds. B Rama Raju E Linga Reddy J Karuppiah P Manoj Kumar Reddy Ch Subrahmanyam. Volume 125 Issue 3 May 2013 pp 673-678 ...

  11. Thermal Decomposition and Phase Formation of Cerate-Zirconate Ceramics Prepared with Different Chelating Agents

    Science.gov (United States)

    Osman, Nafisah; Abdullah, Nur Athirah; Hasan, Sharizal

    2013-07-01

    Chelating agents of citric acid, lactic acid, glycine and ethylenediaminetetra acetic acid (EDTA) were used to synthesize a ceramic compound of Ba(Ce0.6Zr0.4)0.9Y0.1O2.95 (BCZY10) by a sol-gel method. Thermal decomposition and phase formation of the samples were analyzed by thermogravimetric analysis (TGA), Fourier transform infra-red (FTIR) spectroscopy and X-ray diffractometer (XRD). At heating rate of 10 °C min-1, all the samples exhibited almost similar pattern of TG-DTG profiles. A complete thermal decomposition process of the samples took place by three stages. The powders prepared using EDTA exhibited the lowest temperature for thermal decomposition since there was no significant weight loss above than 770 °C. Even after calcined at 1100 °C, the carbonate residue still remains in the samples as proven by FTIR result. The presence of this intermediate phase was also detected in XRD spectra as a small peak at 2θ≈23.9 ° corresponds to BaCO3 appeared for S1, S2 S3 and S4 samples. It was found that the chelating agents used had a decisive influence on the thermal decomposition of samples but no significant effect in reducing calcination temperature to produce a pure perovskite-like phase.

  12. Effect of pre-heating on the thermal decomposition kinetics of cotton

    Science.gov (United States)

    The effect of pre-heating at low temperatures (160-280°C) on the thermal decomposition kinetics of scoured cotton fabrics was investigated by thermogravimetric analysis under nonisothermal conditions. Isoconversional methods were used to calculate the activation energies for the pyrolysis after one-...

  13. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

  14. Effect of Hydration State of Martian Perchlorate Salts on Their Decomposition Temperatures During Thermal Extraction

    Science.gov (United States)

    Royle, Samuel H.; Montgomery, Wren; Kounaves, Samuel P.; Sephton, Mark A.

    2017-12-01

    Three Mars missions have analyzed the composition of surface samples using thermal extraction techniques. The temperatures of decomposition have been used as diagnostic information for the materials present. One compound of great current interest is perchlorate, a relatively recently discovered component of Mars' surface geochemistry that leads to deleterious effects on organic matter during thermal extraction. Knowledge of the thermal decomposition behavior of perchlorate salts is essential for mineral identification and possible avoidance of confounding interactions with organic matter. We have performed a series of experiments which reveal that the hydration state of magnesium perchlorate has a significant effect on decomposition temperature, with differing temperature releases of oxygen corresponding to different perchlorate hydration states (peak of O2 release shifts from 500 to 600°C as the proportion of the tetrahydrate form in the sample increases). Changes in crystallinity/crystal size may also have a secondary effect on the temperature of decomposition, and although these surface effects appear to be minor for our samples, further investigation may be warranted. A less than full appreciation of the hydration state of perchlorate salts during thermal extraction analyses could lead to misidentification of the number and the nature of perchlorate phases present.

  15. Design and implementation of mixing chambers to improve thermal decomposition of urea for NOX abatement

    KAUST Repository

    Lee, Junggil

    2012-10-01

    Urea-selective catalytic reduction (SCR) has been reported as the most promising technique for adherence to NOX emissions regulations. In the urea-SCR process, NH3 is generated by urea thermal decomposition and hydrolysis and is then used as a reductant of NOX in the SCR catalyst. Therefore, improving the NOX conversion efficiency of urea-SCR requires enhancement of thermal decomposition upstream of the SCR catalyst. In the present work, two types of mixing chambers were designed and fabricated to improve urea thermal decomposition, and experiments with and without a mixing chamber were carried out to analyze thermal-decomposition characteristics of urea in the exhaust pipe with respect to inlet velocity (4-12μm/s) and temperature (350°C-500°C). Urea thermal decomposition is greatly enhanced at higher gas temperatures. At an inlet velocity of 6μm/s in the A-type mixing chamber, NH3 concentrations generated along the exhaust pipe were about 171% and 157% greater than those without the mixing chamber for inlet temperatures of 400°C and 500°C, respectively. In the case of the B-type mixing chamber, NH3 concentrations generated at inlet temperatures of 400°C and 500°C were about 147% and 179% greater than those without the mixing chamber, respectively. Note that the implementation of mixing chambers significantly enhanced conversion of urea to NH3 because it increased the residence time of urea in the exhaust pipe and improved mixing between urea and exhaust gas. © 2012, Mary Ann Liebert, Inc.

  16. Thermal decomposition behavior of nano/micro bimodal feedstock with different solids loading

    Science.gov (United States)

    Oh, Joo Won; Lee, Won Sik; Park, Seong Jin

    2018-01-01

    Debinding is one of the most critical processes for powder injection molding. The parts in debinding process are vulnerable to defect formation, and long processing time of debinding decreases production rate of whole process. In order to determine the optimal condition for debinding process, decomposition behavior of feedstock should be understood. Since nano powder affects the decomposition behavior of feedstock, nano powder effect needs to be investigated for nano/micro bimodal feedstock. In this research, nano powder effect on decomposition behavior of nano/micro bimodal feedstock has been studied. Bimodal powders were fabricated with different ratios of nano powder, and the critical solids loading of each powder was measured by torque rheometer. Three different feedstocks were fabricated for each powder depending on solids loading condition. Thermogravimetric analysis (TGA) experiment was carried out to analyze the thermal decomposition behavior of the feedstocks, and decomposition activation energy was calculated. The result indicated nano powder showed limited effect on feedstocks in lower solids loading condition than optimal range. Whereas, it highly influenced the decomposition behavior in optimal solids loading condition by causing polymer chain scission with high viscosity.

  17. Effect of thermal decomposition of hydroxyapatite on the thermoluminescent response

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval C, K. J.; Zarate M, J.; Lemus R, J. [Universidad Michoacana de San Nicolas de Hidalgo, Instituto de Investigaciones Metalurgicas, Ciudad Universitaria, Edificio U, 58060 Morelia, Michoacan (Mexico); Rivera M, T., E-mail: karlasandovalc@gmail.com [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)

    2014-08-15

    In this work, a study on the thermoluminescence (Tl) induced by gamma radiation in synthetic hydroxyapatite (Hap) annealed at different temperatures obtained by the precipitation method is presented. Synthesis of hydroxyapatite Hap was carried out starting from inorganic precursors [Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}]. The precipitate was filtered, washed, dried and then the powder was calcined at different temperatures until the Hap decomposition. The structural and morphological characterization was carried out using both X-ray diffraction (XRD) and scanning electron microscopy (Sem) techniques. Thermoluminescent (Tl) properties of Hap powders were irradiated at different gamma radiation doses. According to X ray diffraction patterns, the tricalcium diphosphate phase (Tcp) appear when the Hap was calcined at 900 grades C. Tl glow curve showed two peaks located at around 200 and 300 grades C, respectively. Tl response as a function of gamma radiation dose was in a wide range from 25 to 100 Gy. The fading of the Tl response at 134 days after irradiation was measured. Experimental results showed that the synthetic hydroxyapatite obtained by precipitation technique may have dosimetric applications when is annealed at temperature of 900 grades C, where the Tcp phase appears and contributes to Tl response, which opens the possibility of using this biomaterials in the area of dosimetry, as they are generally used for biomedical implants. (author)

  18. The products of the thermal decomposition of CH{sub 3}CHO

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliou, AnGayle [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Piech, Krzysztof M.; Barney Ellison, G. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Zhang Xu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 (United States); Nimlos, Mark R. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Ahmed, Musahid; Golan, Amir; Kostko, Oleg [Chemical Sciences Division, Lawrence Berkeley National Laboratory, MS 6R-2100, Berkeley, California 94720 (United States); Osborn, David L. [Combustion Research Facility, Sandia National Laboratories, P.O. Box 969, MS 9055, Livermore, California 94551-0969 (United States); Daily, John W. [Center for Combustion and Environmental Research, Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0427 (United States); Stanton, John F. [Institute for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712 (United States)

    2011-07-07

    We have used a heated 2 cm x 1 mm SiC microtubular ({mu}tubular) reactor to decompose acetaldehyde: CH{sub 3}CHO +{Delta}{yields} products. Thermal decomposition is followed at pressures of 75-150 Torr and at temperatures up to 1675 K, conditions that correspond to residence times of roughly 50-100 {mu}s in the {mu}tubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: vacuum ultraviolet photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH{sub 3}CHO, we have studied three isotopologues, CH{sub 3}CDO, CD{sub 3}CHO, and CD{sub 3}CDO. We have identified the thermal decomposition products CH{sub 3} (PIMS), CO (IR, PIMS), H (PIMS), H{sub 2} (PIMS), CH{sub 2}CO (IR, PIMS), CH{sub 2}=CHOH (IR, PIMS), H{sub 2}O (IR, PIMS), and HC{identical_to}CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH{sub 3}CHO; namely, radical decomposition: CH{sub 3}CHO +{Delta}{yields} CH{sub 3}+[HCO]{yields} CH{sub 3}+ H + CO; elimination: CH{sub 3}CHO +{Delta}{yields} H{sub 2}+ CH{sub 2}=C=O; isomerization/elimination: CH{sub 3}CHO +{Delta}{yields}[CH{sub 2}=CH-OH]{yields} HC{identical_to}CH + H{sub 2}O. An interesting result is that both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH{sub 2}=C:, as an intermediate in the decomposition of vinyl alcohol: CH{sub 2}=CH-OH +{Delta}{yields}[CH{sub 2}=C:]+ H{sub 2}O {yields} HC{identical_to}CH + H{sub 2}O.

  19. Extraction of Curcumin Pigment from Indonesian Local Turmeric with Its Infrared Spectra and Thermal Decomposition Properties

    Science.gov (United States)

    Nandiyanto, A. B. D.; Wiryani, A. S.; Rusli, A.; Purnamasari, A.; Abdullah, A. G.; Ana; Widiaty, I.; Hurriyati, R.

    2017-03-01

    Curcumin is one of the pigments which is used as a spice in Asian cuisine, traditional cosmetic, and medicine. Therefore, process for getting curcumin has been widely studied. Here, the purpose of this study was to demonstrate the simple method for extracting curcumin from Indonesian local turmeric and investigate the infrared spectra and thermal decomposition properties. In the experimental procedure, the washed turmeric was dissolved into an ethanol solution, and then put into a rotary evaporator to enrich curcumin concentration. The result showed that the present method is effective to isolate curcumin compound from Indonesian local turmeric. Since the process is very simple, this method can be used for home industrial application. Further, understanding the thermal decomposition properties of curcumin give information, specifically relating to the selection of treatment when curcumin must face the thermal-related process.

  20. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis

    OpenAIRE

    Valverde, J.M.; Perejón, Antonio; Medina, Santiago; Pérez-Maqueda, Luis A.

    2015-01-01

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs whe...

  1. Kinetic Parameters of Thermal Decomposition Process Analyzed using a Mathematical Model

    Science.gov (United States)

    Nandiyanto, A. B. D.; Ekawati, R.; Wibawa, S. C.

    2018-01-01

    The purpose of this study was to show a mathematical analysis model for understanding kinetic parameters of thermal decomposition process. The mathematical model was derived based on phenomena happen during the thermal-related reaction. To get the kinetic parameters (i.e. reaction order, activation energy, and Arrhenius constant), the model was combined with the thermal characteristics of material gained from the thermal gravity (TG) and differential thermal analysis (DTA) curves. As an example, the model was used for analyzing the kinetic properties of trinitrotoluene. Interestingly, identical results gained from the present model with current literatures were obtained; in which these were because the present model was derived directly from the analysis of stoichiometrical and thermal analysis of the ideal chemical reaction. Since the present model confirmed to have a good agreement with current theories, further derivation from the present mathematical model can be useful for further development.

  2. Kinetic Study and Thermal Decomposition Behavior of Lignite Coal

    Directory of Open Access Journals (Sweden)

    Mehran Heydari

    2015-01-01

    Full Text Available A thermogravimetric analyzer was employed to investigate the thermal behavior and extract the kinetic parameters of Canadian lignite coal. The pyrolysis experiments were conducted in temperatures ranging from 298 K to 1173 K under inert atmosphere utilizing six different heating rates of 1, 6, 9, 12, 15, and 18 K min−1, respectively. There are different techniques for analyzing the kinetics of solid-state reactions that can generally be classified into two categories: model-fitting and model-free methods. Historically, model-fitting methods are broadly used in solid-state kinetics and show an excellent fit to the experimental data but produce uncertain kinetic parameters especially for nonisothermal conditions. In this work, different model-free techniques such as the Kissinger method and the isoconversional methods of Ozawa, Kissinger-Akahira-Sunose, and Friedman are employed and compared in order to analyze nonisothermal kinetic data and investigate thermal behavior of a lignite coal. Experimental results showed that the activation energy values obtained by the isoconversional methods were in good agreement, but Friedman method was considered to be the best among the model-free methods to evaluate kinetic parameters for solid-state reactions. These results can provide useful information to predict kinetic model of coal pyrolysis and optimization of the process conditions.

  3. Mechanistic and kinetic studies of the thermal decomposition of TNAZ and NDNAZ

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, K.; Homsy, J.; Behrens, R. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility; Bulusu, S. [Army Armament Research, Development and Engineering Center, Dover, NJ (United States). Energetic Materials Div.

    1998-12-31

    The authors have studied the mechanism and detailed reaction kinetics of the thermal decomposition of 1,3,3-trinitroazetidine (TNAZ), and separately, its key decomposition intermediate, 1-nitroso-3,3-dinitroacetidine (NDNAZ), using a simultaneous thermogravimetric modulated beam mass spectrometer (STMBMS). These decompositions were conducted in a sealed alumina cell with a 2.5 {micro}m orifice, at varying temperatures and at a range of isothermal temperatures (at 10 C intervals from 120--160 C for NDNAZ and 160--210 C for TNAZ). The gaseous products have been identified and their rates of formation have been measured as a function of time, temperature, and pressure. This system is complex, with TNAZ decomposing by four separate routes, one of which leads to NDNAZ, which itself decomposes by at least two distinct routes.

  4. Structural effects and thermal decomposition kinetics of chalcones under non-isothermal conditions

    Directory of Open Access Journals (Sweden)

    G. Manikandan

    2016-09-01

    Full Text Available Two chalcones namely, 1,5-bis(4-hydroxy-3-methoxyphenylpentan-1,4-dien-3-one (BHMPD and 2,5-bis(4-hydroxy-3-methoxybenzylidenecyclopentanone (BHMBC have been synthesised and characterized by microanalysis, FT-IR, mass spectra and NMR (1H and 13C techniques. The thermal decomposition of these compounds was studied by TGA and DTA under dynamic nitrogen atmosphere at different heating rates of 10, 15 and 20 K min−1. The kinetic parameters were calculated using model-fitting (Coats–Redfern, CR and model-free methods (Friedman, Kissinger–Akahira–Sunose, KAS and Flynn–Wall–Ozawa, FWO. The decomposition process of BHMPD and BHMBC followed a single step mechanism as evidenced from the data. Existence of compensation effect was noticed for the decomposition of these compounds. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS isoconversional method in both compounds.

  5. Kinetic study of the thermal decomposition of poly(vinyl alcohol)/kraft lignin derivative blends

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, D.M. [Departamento de Quimica, Universidade Estadual de Maringa, Av. Colombo 5790, 87020-900 Maringa, PR (Brazil); Hechenleitner, A.A. Winkler [Departamento de Quimica, Universidade Estadual de Maringa, Av. Colombo 5790, 87020-900 Maringa, PR (Brazil); Pineda, E.A. Gomez [Departamento de Quimica, Universidade Estadual de Maringa, Av. Colombo 5790, 87020-900 Maringa, PR (Brazil)]. E-mail: eagpineda@uem.br

    2006-02-01

    A kraft lignin derivative (KLD) obtained by reaction with p-aminobenzoic acid/phthalic anhydride, was blended with poly(vinyl alcohol) (PVA) by solution casting from DMSO. PVA and PVA/KLD films were exposed to ultraviolet radiation (Hg lamp, 96 h) and analyzed by thermogravimetry (TG) in inert and oxidative atmosphere. Typical multi-step decomposition profiles were obtained. The apparent activation energy (E {sub a}) of the thermal degradation of the samples was computed by the Vyazovkin method. The KLD degradation presented only small intervals of decomposition deg.ree with constant E {sub a} values. PVA and blends showed intervals of up to 50% in decomposition deg.ree with nearly constant E {sub a}, and smaller intervals in which E {sub a} varies drastically. The influences of samples irradiation and of surrounding gas in TG analysis on E {sub a} are also shown.

  6. Thermal decomposition of MgCO3 during the atmospheric entry of micrometeoroids

    Science.gov (United States)

    Micca Longo, G.; Longo, S.

    2017-10-01

    In this paper, a first study of the atmospheric entry of carbonate micrometeoroids, in an astrobiological perspective, is performed. Therefore an entry model, which includes two-dimensional dynamics, non-isothermal atmosphere, ablation and radiation losses, is build and benchmarked to literature data for silicate micrometeoroids. A thermal decomposition model of initially pure magnesium carbonate is proposed, and it includes thermal energy, mass loss and the effect of changing composition as the carbonate grain is gradually converted into oxide. Several scenarios are obtained by changing the initial speed, entry angle and grain diameter, producing a systematic comparison of silicate and carbonate grain. The results of the composite model show that the thermal behaviour of magnesium carbonate is markedly different from that of the corresponding silicate, much lower equilibration temperatures being reached in the first stages of the entry. At the same time, the model shows that the limit of a thermal protection scenario, based on magnesium carbonate, is the very high decomposition speed even at moderate temperatures, which results in the total loss of carbon already at about 100 km altitude. The present results show that, although decomposition and associated cooling are important effects in the entry process of carbonate grains, the specific scenario of pure MgCO3 micrograin does not allow complex organic matter delivery to the lower atmosphere. This suggests us to consider less volatile carbonates for further studies.

  7. Synthesis and Characterization of [60]Fullerene-Glycidyl Azide Polymer and Its Thermal Decomposition

    Directory of Open Access Journals (Sweden)

    Ting Huang

    2015-05-01

    Full Text Available A new functionalized [60]fullerene-glycidyl azide polymer (C60-GAP was synthesized for the first time using a modified Bingel reaction of [60]fullerene (C60 and bromomalonic acid glycidyl azide polymer ester (BM-GAP. The product was characterized by Fourier transform infrared (FTIR, ultraviolet-visible (UV-Vis, and nuclear magnetic resonance spectroscopy (NMR analyses. Results confirmed the successful preparation of C60-GAP. Moreover, the thermal decomposition of C60-GAP was analyzed by differential scanning calorimetry (DSC, thermogravimetric analysis coupled with infrared spectroscopy (TGA-IR, and in situ FTIR. C60-GAP decomposition showed a three-step thermal process. The first step was due to the reaction of the azide group and fullerene at approximately 150 °C. The second step was ascribed to the remainder decomposition of the GAP main chain and N-heterocyclic at approximately 240 °C. The final step was attributed to the burning decomposition of amorphous carbon and carbon cage at around 600 °C.

  8. Exothermic Behavior of Thermal Decomposition of Sodium Percarbonate: Kinetic Deconvolution of Successive Endothermic and Exothermic Processes.

    Science.gov (United States)

    Nakano, Masayoshi; Wada, Takeshi; Koga, Nobuyoshi

    2015-09-24

    This study focused on the kinetic modeling of the thermal decomposition of sodium percarbonate (SPC, sodium carbonate-hydrogen peroxide (2/3)). The reaction is characterized by apparently different kinetic profiles of mass-loss and exothermic behavior as recorded by thermogravimetry and differential scanning calorimetry, respectively. This phenomenon results from a combination of different kinetic features of the reaction involving two overlapping mass-loss steps controlled by the physico-geometry of the reaction and successive endothermic and exothermic processes caused by the detachment and decomposition of H2O2(g). For kinetic modeling, the overall reaction was initially separated into endothermic and exothermic processes using kinetic deconvolution analysis. Then, both of the endothermic and exothermic processes were further separated into two reaction steps accounting for the physico-geometrically controlled reaction that occurs in two steps. Kinetic modeling through kinetic deconvolution analysis clearly illustrates the appearance of the net exothermic effect is the result of a slight delay of the exothermic process to the endothermic process in each physico-geometrically controlled reaction step. This demonstrates that kinetic modeling attempted in this study is useful for interpreting the exothermic behavior of solid-state reactions such as the oxidative decomposition of solids and thermal decomposition of oxidizing agent.

  9. Silver Nanoparticles and Graphitic Carbon Through Thermal Decomposition of a Silver/Acetylenedicarboxylic Salt

    Directory of Open Access Journals (Sweden)

    Komninou Philomela

    2009-01-01

    Full Text Available Abstract Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 °C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp2carbon at the Raman spectrum of both samples.

  10. Thermal conductivity decomposition in two-dimensional materials: Application to graphene

    Science.gov (United States)

    Fan, Zheyong; Pereira, Luiz Felipe C.; Hirvonen, Petri; Ervasti, Mikko M.; Elder, Ken R.; Donadio, Davide; Ala-Nissila, Tapio; Harju, Ari

    2017-04-01

    Two-dimensional materials have unusual phonon spectra due to the presence of flexural (out-of-plane) modes. Although molecular dynamics simulations have been extensively used to study heat transport in such materials, conventional formalisms treat the phonon dynamics isotropically. Here, we decompose the microscopic heat current in atomistic simulations into in-plane and out-of-plane components, corresponding to in-plane and out-of-plane phonon dynamics, respectively. This decomposition allows for direct computation of the corresponding thermal conductivity components in two-dimensional materials. We apply this decomposition to study heat transport in suspended graphene, using both equilibrium and nonequilibrium molecular dynamics simulations. We show that the flexural component is responsible for about two-thirds of the total thermal conductivity in unstrained graphene, and the acoustic flexural component is responsible for the logarithmic divergence of the conductivity when a sufficiently large tensile strain is applied.

  11. First-Principles Thermochemistry for the Thermal Decomposition of Titanium Tetraisopropoxide.

    Science.gov (United States)

    Buerger, Philipp; Nurkowski, Daniel; Akroyd, Jethro; Mosbach, Sebastian; Kraft, Markus

    2015-07-30

    The thermal decomposition of titanium tetraisopropoxide (TTIP) is investigated using quantum chemistry, statistical thermodynamics, and equilibrium composition analysis. A set of 981 Ti-containing candidate species are proposed systematically on the basis of the thermal breakage of bonds within a TTIP molecule. The ground state geometry, vibrational frequencies and hindrance potentials are calculated for each species at the B97-1/6-311+G(d,p) level of theory. Thermochemical data are computed by applying statistical thermodynamics and, if unknown, the standard enthalpy of formation is estimated using balanced reactions. Equilibrium composition calculations are performed under typical combustion conditions for premixed flames. The thermodynamically stable decomposition products for different fuel mixtures are identified. A strong positive correlation is found between the mole fractions of Ti species containing carbon and the TTIP precursor concentration.

  12. Decomposition kinetics study of zirconium hydride by interrupted thermal desorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Mingwang; Liang, Li; Tang, Binghua; Xiang, Wei; Wang, Yuan; Cheng, Yanlin; Tan, Xiaohua, E-mail: caepiee@163.com

    2015-10-05

    Highlights: • Interrupted TDS was applied to investigate the mechanism of ZrH{sub 2} decomposition. • The activation energies for the five desorption peaks were determined. • The origins of the five desorption peaks were identified. • The γZrH phase was observed at ambient conditions. - Abstract: Thermal desorption kinetics of zirconium hydride powder were studied using thermogravimetry and simultaneous thermal desorption spectroscopy. The activation energies for observed desorption peaks were estimated according to Kissinger relation. The intermediate phase composition was studied using X-ray diffraction by rapid cooling on different stages of heating. The origins of the peaks were described as the equilibrium hydrogen pressure of a number of consecutive phase regions that decomposition reaction passed through. The zirconium monohydride γZrH was observed for extended periods of time at ambient conditions, which has been supposed to be metastable for a long time.

  13. Synthesis of Copper Nanoparticles by Thermal Decomposition and Their Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    R. Betancourt-Galindo

    2014-01-01

    Full Text Available Copper nanoparticles were synthesized by thermal decomposition using copper chloride, sodium oleate, and phenyl ether as solvent agents. The formation of nanoparticles was evidenced by the X-ray diffraction and transmission electron microscopy. The peaks in the XRD pattern correspond to the standard values of the face centered cubic (fcc structure of metallic copper and no peaks of other impurity crystalline phases were detected. TEM analysis showed spherical nanoparticles with sizes in the range of 4 to 18 nm. The antibacterial properties of copper nanoparticles were evaluated in vitro against strains of Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activity of copper nanoparticles synthesized by thermal decomposition showed significant inhibitory effect against these highly multidrug-resistant bacterial strains.

  14. A Property Extracted by Composition / Thermal Decomposition Analyses of Various Biomass Resources and Its Correlation

    Science.gov (United States)

    Mizuno, Satoru; Morita, Akihiro; Ida, Tamio; Namba, Kunihiko; Fuchihata, Manabu; Sawai, Toru

    Effective utilization of biomass resource rapidly has been promoting since the government adopted the ‘Biomass Nippon’ strategy at a cabinet meeting in 2002. Especially, the energy conversion technology of applying biomass has been expected from a point of view of environment and resource conservation. However, the energy conversion technologies are developed only for woody and herby biomass, and not for all of biomass. A stable supply of large quantity of biomass will be pressed in the future because the conversion technology must expand to use a variety of biomass. This study is to consider ways by various quantitative correlation analyses between the atomic composition and thermal decomposition of various biomass samples. The results found that thermal decomposition analyses of various biomass resources have correlations between atomic composition properties and exothermic properties.

  15. Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongyan, E-mail: hongyan.sun1@gmail.com, E-mail: ghanshyam.vaghjiani@us.af.mil; Vaghjiani, Ghanshyam L., E-mail: hongyan.sun1@gmail.com, E-mail: ghanshyam.vaghjiani@us.af.mil [Propellants Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRP, 10 E. Saturn Blvd., Edwards AFB, California 93524 (United States)

    2015-05-28

    Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH{sub 2} group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C{sub 2v} symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice–Ramsperger–Kassel–Marcus/multi-well master equation simulations, the results of which

  16. Solar production of catalytic filamentous carbon by thermal decomposition of hydrocarbons and carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, V.A.; Kuvshinov, G.G.; Mogilnykh, Yu.I. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Reller, A. [University of Hamburg (Germany); Steinfeld, A.; Weidenkaff, A.; Meier, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Concentrated solar radiation was used as the clean source of process heat for the production of Catalytic Filamentous Carbon (CFC) by thermal decomposition of gaseous hydrocarbons and by CO disproportionation in the presence of small metal catalyst particles. Depending on the catalyst, two different types of CFC, namely nano tubes and nano fibers, were obtained in solar experiments at the PSI solar furnace. (author) 2 figs., 1 tab., 7 refs.

  17. Critical Rate of Thermal Decomposition of Pure and Impregnated Lignocellulosic Materials

    Science.gov (United States)

    Chrebet, Tomáš; Balog, Karol

    2010-01-01

    Contribution deals with monitoring the impact of airflow velocity around the sample, the oven temperature during thermal decomposition and nature of the sample for the minimum mass flux rate needed to initiate flame combustion. We used the samples of lignocellulosic materials, particularly spruce wood, pure cellulose, flax, cellulose impregnated by 5%, 10%, 15% water solution of KHCO3 and by 5%, 10%, 15% water solution of (NH4)2HPO4.

  18. Thermal decomposition behavior of amino groups modified bimodal mesoporous silicas as aspirin carrier.

    Science.gov (United States)

    Gao, Lin; Sun, Jihong; Zhang, Li; Li, Yuzhen; Ren, Bo

    2011-12-01

    Two kinds of amino groups were employed to functionalize bimodal mesoporous silicas and related drug carriers were prepared. The characterization results of XRD, N2 adsorption and desorption, FT-IR and TG all confirmed the structural integrity of the bimodal mesopore architecture after introduction treatment of functional groups and the successful adsorption of aspirin. In order to investigate the interaction among the mesoporous structure, the functional groups grafted onto the mesoporous surface and the existential microenvironment of the drug molecules inside the mesoporous channels, the thermal decomposition behaviors of amino groups modified and aspirin loaded carriers were studied based on the thermogravimetric analysis in details. According to the thermogravimetry and derivative thermogravimetry results, the apparent activation energies E(a) of thermal decomposition for all related samples have been evaluated by Kissinger and Flynn-Wall-Ozawa methods. Meanwhile, their thermal decomposition mechanisms have been suggested by using Coats and Redfern methods. All these featured consequence could provide a deeper understanding for large loading capacity and controlled release of drug-carriers in the pharmaceutical application.

  19. Physical pretreatments of wastewater algae to reduce ash content and improve thermal decomposition characteristics.

    Science.gov (United States)

    Chen, Wan-Ting; Ma, Junchao; Zhang, Yuanhui; Gai, Chao; Qian, Wanyi

    2014-10-01

    Previous study showed high ash content in wastewater algae (WA) has a negative effect on bio-crude oil formation in hydrothermal liquefaction (HTL). This study explored the effect of different pretreatments on ash reduction and the thermal decomposition of WA. Single-stage (e.g. centrifugation) and two-stage pretreatments (e.g. centrifugation followed by ultrasonication, C+U) were used. The apparent activation energy of the thermal decomposition (E(a)) of pretreated algae was determined. HTL was conducted to study how different pretreatments may impact on bio-crude oil formation. Compared to untreated samples, the ash content of algae with centrifugation was reduced from 28.6% to 18.6%. With C+U pretreatments, E(a) was decreased from 50.2 kJ/mol to 35.9 kJ/mol and the bio-crude oil yield was increased from 30% to 55%. These results demonstrate that pretreatments of C+U can improve the thermal decomposition behavior of WA and enhance the bio-crude oil conversion efficiency. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Study on the kinetics and mechanism of grain growth during the thermal decomposition of magnesite

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Daxue; Feng, Naixiang; Wang, Yaowu [Northeastern Univ., Shenyang (China)

    2012-04-15

    The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in CO{sub 2} or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, D{sup n} = kt, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and 1.56 X 10{sup 8} nm{sup 4}/s, respectively. Raman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

  1. Study on the kinetics and mechanism of grain growth during the thermal decomposition of magnesite

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Daxue; Feng, Naixiang; Wang, Yaowu [Northeastern Univ., Shenyang (China)

    2012-04-15

    The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in CO{sub 2} or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, D{sup n} = kt, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and 1.56 X 10{sup 8} nm{sup 4}/s, respectively. Ran man spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

  2. Prediction of the thermal decomposition of organic peroxides by validated QSPR models

    Energy Technology Data Exchange (ETDEWEB)

    Prana, Vinca [Institut de Recherche de Chimie Paris, Chimie ParisTech CNRS, 11 rue P. et M. Curie, Paris 75005 (France); Institut National de l’Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP2, Verneuil-en-Halatte 60550 (France); Rotureau, Patricia, E-mail: patricia.rotureau@ineris.fr [Institut National de l’Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP2, Verneuil-en-Halatte 60550 (France); Fayet, Guillaume [Institut National de l’Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP2, Verneuil-en-Halatte 60550 (France); André, David; Hub, Serge [ARKEMA, rue Henri Moissan, BP63, Pierre Benite 69493 (France); Vicot, Patricia [Institut National de l’Environnement Industriel et des Risques (INERIS), Parc Technologique Alata, BP2, Verneuil-en-Halatte 60550 (France); Rao, Li [Institut de Recherche de Chimie Paris, Chimie ParisTech CNRS, 11 rue P. et M. Curie, Paris 75005 (France); Adamo, Carlo [Institut de Recherche de Chimie Paris, Chimie ParisTech CNRS, 11 rue P. et M. Curie, Paris 75005 (France); Institut Universitaire de France, 103 Boulevard Saint Michel, Paris F-75005 (France)

    2014-07-15

    Highlights: • QSPR models were developed for thermal stability of organic peroxides. • Two accurate MLR models were exhibited based on quantum chemical descriptors. • Performances were evaluated by a series of internal and external validations. • The new QSPR models satisfied all OCDE principles of validation for regulatory use. - Abstract: Organic peroxides are unstable chemicals which can easily decompose and may lead to explosion. Such a process can be characterized by physico-chemical parameters such as heat and temperature of decomposition, whose determination is crucial to manage related hazards. These thermal stability properties are also required within many regulatory frameworks related to chemicals in order to assess their hazardous properties. In this work, new quantitative structure–property relationships (QSPR) models were developed to predict accurately the thermal stability of organic peroxides from their molecular structure respecting the OECD guidelines for regulatory acceptability of QSPRs. Based on the acquisition of 38 reference experimental data using DSC (differential scanning calorimetry) apparatus in homogenous experimental conditions, multi-linear models were derived for the prediction of the decomposition heat and the onset temperature using different types of molecular descriptors. Models were tested by internal and external validation tests and their applicability domains were defined and analyzed. Being rigorously validated, they presented the best performances in terms of fitting, robustness and predictive power and the descriptors used in these models were linked to the peroxide bond whose breaking represents the main decomposition mechanism of organic peroxides.

  3. Thermal Analysis of the Decomposition of Ammonium Uranyl Carbonate (AUC) in Different Atmospheres

    DEFF Research Database (Denmark)

    Hälldahl, L.; Sørensen, Ole Toft

    1979-01-01

    The intermediate products formed during thermal decomposition of ammonium uranyl carbonate (AUC) in different atmospheres, (air, helium and hydrogen) have been determined by thermal analysis, (TG, and DTA) and X-ray analysis. The endproducts observed are U3O8 and UO2 in air/He and hydrogen......, respectively. The following intermediate products were observed in all atmospheres: http://www.sciencedirect.com.globalproxy.cvt.dk/cache/MiamiImageURL/B6THV-44K80TV-FB-1/0?wchp=dGLzVlz-zSkWW X-ray diffraction analysis showed that these phases were amorphous....

  4. Thermal decomposition and kinetics of plastic bonded explosives based on mixture of HMX and TATB with polymer matrices

    Directory of Open Access Journals (Sweden)

    Arjun Singh

    2017-02-01

    Full Text Available This work describes thermal decomposition behaviour of plastic bonded explosives (PBXs based on mixture of l,3,5,7-tetranitro- 1,3,5,7-tetrazocane (HMX and 2,4,6- triamino-1,3,5-trinitrobenzene (TATB with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis (STA and differential scanning calorimetry (DSC to investigate influence of the HMX amount on thermal behavior and its kinetics. Thermogravimetric analysis (TGA indicated that the thermal decomposition of PBXs based on mixture of HMX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HMX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HMX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HMX and TATB was observed with varying the HMX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn–Wall–Ozawa (FWO and Kissinger-Akahira-Sunose (KAS methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.

  5. Prediction of the thermal decomposition of organic peroxides by validated QSPR models.

    Science.gov (United States)

    Prana, Vinca; Rotureau, Patricia; Fayet, Guillaume; André, David; Hub, Serge; Vicot, Patricia; Rao, Li; Adamo, Carlo

    2014-07-15

    Organic peroxides are unstable chemicals which can easily decompose and may lead to explosion. Such a process can be characterized by physico-chemical parameters such as heat and temperature of decomposition, whose determination is crucial to manage related hazards. These thermal stability properties are also required within many regulatory frameworks related to chemicals in order to assess their hazardous properties. In this work, new quantitative structure-property relationships (QSPR) models were developed to predict accurately the thermal stability of organic peroxides from their molecular structure respecting the OECD guidelines for regulatory acceptability of QSPRs. Based on the acquisition of 38 reference experimental data using DSC (differential scanning calorimetry) apparatus in homogenous experimental conditions, multi-linear models were derived for the prediction of the decomposition heat and the onset temperature using different types of molecular descriptors. Models were tested by internal and external validation tests and their applicability domains were defined and analyzed. Being rigorously validated, they presented the best performances in terms of fitting, robustness and predictive power and the descriptors used in these models were linked to the peroxide bond whose breaking represents the main decomposition mechanism of organic peroxides. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Peculiarities of obtaining a catalyst for the synthesis of nanostructured carbon materials via thermal decomposition

    Science.gov (United States)

    Dyachkova, Tatyana; Besperstova, Galina; Burakova, Elena; Rukhov, Artem; Tugolukov, Evgeny

    2017-11-01

    The paper presents the peculiarities of catalysts preparation through thermal decomposition and calcination. We propose methods for the evaluation of reagents solubility and decomposition degree that allow eliminating and adapting (NH4)6Mo7O24.4H2O, which does not meet the reagent solubility requirements contain (NH4)2MoO4, to obtain catalyst used to synthesize carbon nanotubes (CNTs) with a diameter of 5-30 nm via chemical vapor deposition. The density (1510…1515 kg/m3) and electrical conductivity (1.54….1.72 µS/cm) experimentally found for the initial solution make it possible to control the pre-catalyst quality prior to the thermal decomposition stage. With the help of obtained Co-Mo/Al2O3-MgO catalyst CNTs yield was achieved as 10.3… 11.9 and 20.3…23.0 [gram of CNTs / gram of catalysts] when using ethylene and propane-butane mixture as a carbon-containing gas, respectively.

  7. Synthesis and thermal decomposition of a novel zirconium acetato-propionate cluster: [Zr12

    Science.gov (United States)

    Petit, Sarah; Morlens, Stéphanie; Yu, Zeming; Luneau, Dominique; Pilet, Guillaume; Soubeyroux, Jean-Louis; Odier, Philippe

    2011-03-01

    This work reports a novel Zirconium acetato-propionate complex herein called [Zr12] obtained by reaction of zirconium acetylacetonate Zr(acac) 4 with propionic acid. The molecular structure has been determined by X-ray diffraction on single crystals and proposed to be [Zr 12(μ 3-O) 16(CH 3CH 2CO 2) 12(CH 3CO 2) 8(μ 2-CH 3CH 2CO 2) 4]. This cluster involves oxo/hydroxo bonds in the direct surrounding of the metallic center. The decomposition of [Zr12] has been studied by thermal analysis and compared to Zr(acac) 4. Its temperature of decomposition is much lower than for acetylacetonate derivative. In consequence, the formation of ZrO 2 is easier from [Zr12] than from Zr(acac) 4. This phenomenon highlights the influence of the molecular structure on the process of decomposition. The local surrounding of Zr in [Zr12] and in ZrO 2 are very close, while it is markedly different in Zr(acac) 4.This difference of environment of the metallic ions is at the origin of the huge difference of thermal behavior of both compounds.

  8. Vibrational Order, Structural Properties, and Optical Gap of ZnO Nanostructures Sintered through Thermal Decomposition

    Directory of Open Access Journals (Sweden)

    Alejandra Londono-Calderon

    2014-01-01

    Full Text Available The sintering of different ZnO nanostructures by the thermal decomposition of zinc acetate is reported. Morphological changes from nanorods to nanoparticles are exhibited with the increase of the decomposition temperature from 300 to 500°C. The material showed a loss in the crystalline order with the increase in the temperature, which is correlated to the loss of oxygen due to the low heating rate used. Nanoparticles have a greater vibrational freedom than nanorods which is demonstrated in the rise of the main Raman mode E 2(high during the transformation. The energy band gap of the nanostructured material is lower than the ZnO bulk material and decreases with the rise in the temperature.

  9. Synthesis, Optical Characterization, and Thermal Decomposition of Complexes Based on Biuret Ligand

    Directory of Open Access Journals (Sweden)

    Mei-Ling Wang

    2016-01-01

    Full Text Available Four complexes were synthesized in methanol solution using nickel acetate or nickel chloride, manganese acetate, manganese chloride, and biuret as raw materials. The complexes were characterized by elemental analyses, UV, FTIR, Raman spectra, X-ray powder diffraction, and thermogravimetric analysis. The compositions of the complexes were [Ni(bi2(H2O2](Ac2·H2O (1, [Ni(bi2Cl2] (2, [Mn(bi2(Ac2]·1.5H2O (3, and [Mn(bi2Cl2] (4 (bi = NH2CONHCONH2, respectively. In the complexes, every metal ion was coordinated by oxygen atoms or chlorine ions and even both. The nickel and manganese ions were all hexacoordinated. The thermal decomposition processes of the complexes under air included the loss of water molecule, the pyrolysis of ligands, and the decomposition of inorganic salts, and the final residues were nickel oxide and manganese oxide, respectively.

  10. Simultaneous differential scanning calorimetry and thermal desorption spectroscopy measurements for the study of the decomposition of metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.F.; Cuevas, F.; Sanchez, C. [Univ. Autonoma, Madrid (Spain). Dept de Fisica de Materiales C-IV

    2000-02-28

    An innovative experimental method to investigate the thermal decomposition of metal hydrides is presented. The method is based on an experimental setup composed of a differential scanning calorimeter connected through a capillary tube to a mass spectrometer. The experimental system allows the simultaneous determination of the heat absorbed and the hydrogen evolved from a metal hydride during thermal decomposition. This arrangement constitutes a coupled differential scanning calorimetry (DSC) and thermal desorption spectroscopy (TDS) technique. It has been applied to metal hydride materials to demonstrate the capability of the experimental system. A method to obtain the heat of decomposition of metal hydrides is described. It involves the measurement of an apparent decomposition heat as a function of the carrier gas flow. (orig.)

  11. A quasimechanism of melt acceleration in the thermal decomposition of crystalline organic solids

    Energy Technology Data Exchange (ETDEWEB)

    Henson, Bryan F [Los Alamos National Laboratory

    2009-01-01

    It has been know for half a century that many crystalline organic solids undergo an acceleration in the rate of thermal decomposition as the melting temperature is approached. This acceleration terminates at the melting point, exhibiting an Arrhenius-like temperature dependence in the faster decomposition rate from the liquid phase. This observation has been modeled previously using various premelting behaviors based on e.g. freezing point depression induced by decomposition products or solvent impurities. These models do not, however, indicate a mechanism for liquid formation and acceleration which is an inherent function of the bulk thermodynamics of the molecule. Here we show that such an inherent thermodynamic mechanism for liquid formation exists in the form of the so-called quasi-liquid layer at the solid surface. We explore a kinetic mechanism which describes the acceleration of rate and is a function of the free energies of sublimation and vaporization. We construct a differential rate law from these thermodynamic free energies and a normalized progress variable. We further construct a reduced variable formulation of the model which is a simple function of the metastable liquid activity below the melting point, and show that it is applicable to the observed melt acceleration in several common organic crystalline solids. A component of the differential rate law, zero order in the progress variable, is shown to be proportional to the thickness of the quasiliquid layer predicted by a recent thermodynamic theory for this phenomenon. This work therefore serves not only to provide new insight into thermal decomposition in a broad class or organic crystalline solids, but also further validates the underlying thermodynamic nature of the phenomenon of liquid formation on the molecular surface at temperatures below the melting point.

  12. Mass spectrometry characterization of the thermal decomposition/digestion (TDD) at cysteine in peptides and proteins in the condensed phase.

    Science.gov (United States)

    Basile, Franco; Zhang, Shaofeng; Kandar, Sujit Kumar; Lu, Liang

    2011-11-01

    We report on the characterization by mass spectrometry (MS) of a rapid, reagentless and site-specific cleavage at the N-terminus of the amino acid cysteine (C) in peptides and proteins induced by the thermal decomposition at 220-250 °C for 10 s in solid samples. This thermally induced cleavage at C occurs under the same conditions and simultaneously to our previously reported thermally induced site-specific cleavage at the C-terminus of aspartic acid (D) (Zhang, S.; Basile, F. J. Proteome Res. 2007, 6, (5), 1700-1704). The C cleavage proceeds through cleavage of the nitrogen and α-carbon bond (N-terminus) of cysteine and produces modifications at the cleavage site with an amidation (-1 Da) of the N-terminal thermal decomposition product and a -32 Da mass change of the C-terminal thermal decomposition product, the latter yielding either an alanine or β-alanine residue at the N-terminus site. These modifications were confirmed by off-line thermal decomposition electrospray ionization (ESI)-MS, tandem MS (MS/MS) analyses and accurate mass measurements of standard peptides. Molecular oxygen was found to be required for the thermal decomposition and cleavage at C as it induced an initial cysteine thiol side chain oxidation to sulfinic acid. Similar to the thermally induced D cleavage, missed cleavages at C were also observed. The combined thermally induced digestion process at D and C, termed thermal decomposition/digestion (TDD), was observed on several model proteins tested under ambient conditions and the site-specificity of the method confirmed by MS/MS.

  13. Structure-Activity Relationship Analysis of the Thermal Stabilities of Nitroaromatic Compounds Following Different Decomposition Mechanisms.

    Science.gov (United States)

    Li, Jiazhong; Liu, Huanxiang; Huo, Xing; Gramatica, Paola

    2013-02-01

    The decomposition behavior of energetic materials is very important for the safety problems concerning their production, transportation, use and storage, because molecular decomposition is intimately connected to their explosive properties. Nitroaromatic compounds, particularly nitrobenzene derivatives, are often considered as prototypical energetic molecules, and some of them are commonly used as high explosives. Quantitative structure-activity relationship (QSAR) represents a potential tool for predicting the thermal stability properties of energetic materials. But it is reported that constructing general reliable models to predict their stability and their potential explosive properties is a very difficult task. In this work, we make our efforts to investigate the relationship between the molecular structures and corresponding thermal stabilities of 77 nitrobenzene derivatives with various substituent functional groups (in ortho, meta and/or para positions). The proposed best MLR model, developed by the new software QSARINS, based on Genetic Algorithm for variable selection and with various validation tools, is robust, stable and predictive with R(2) of 0.86, QLOO (2) of 0.79 and CCC of 0.90. The results indicated that, though difficult, it is possible to build predictive, externally validated QSAR models to estimate the thermal stability of nitroaromatic compounds. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Effect of Nano-Magnesium Hydride on the Thermal Decomposition Behaviors of RDX

    Directory of Open Access Journals (Sweden)

    Miao Yao

    2013-01-01

    Full Text Available In order to improve the detonation performance of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX explosive, addictives with high heat values were used, and magnesium hydride (MgH2 is one of the candidates. However, it is important to see whether MgH2 is a safe addictive. In this paper, the thermal and kinetic properties of RDX and mixture of RDX/MgH2 were investigated by differential scanning calorimeter (DSC and accelerating rate calorimeter (ARC, respectively. The apparent activation energy (E and frequency factor (A of thermal explosion were calculated based on the data of DSC experiments using the Kissinger and Ozawa approaches. The results show that the addition of MgH2 decreases both E and A of RDX, which means that the mixture of RDX/MgH2 has a lower thermal stability than RDX, and the calculation results obtained from the ARC experiments data support this too. Besides, the most probable mechanism functions about the decomposition of RDX and RDX/MgH2 were given in this paper which confirmed the change of the decomposition mechanism.

  15. Some peculiarities of zirconium tungstate synthesis by thermal decomposition of hydrothermal precursors

    Energy Technology Data Exchange (ETDEWEB)

    Gubanov, Alexander I., E-mail: gubanov@niic.nsc.su [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Dedova, Elena S. [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, pr. Akademicheskii 2/4, 634021 Tomsk (Russian Federation); Tomsk Polytechnic University, Lenin Avenue 30, 634050 Tomsk (Russian Federation); Plyusnin, Pavel E.; Filatov, Eugeny Y. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Kardash, Tatyana Y. [Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 5, 630090 Novosibirsk (Russian Federation); Korenev, Sergey V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Kulkov, Sergey N. [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, pr. Akademicheskii 2/4, 634021 Tomsk (Russian Federation); Tomsk Polytechnic University, Lenin Avenue 30, 634050 Tomsk (Russian Federation)

    2014-12-10

    Highlights: • Synthesis of ZrW{sub 2}O{sub 8} using hydrothermal method. • On hydrothermal synthesis optimal conc. of HCl in the reaction mixture is 2.3 M. • Thermal decomposition of ZrW{sub 2}O{sub 7}((OH){sub 1.5},Cl{sub 0.5})·2H{sub 2}O begins are 200 °S. • Amorphous intermediate crystallizes into cubic single-phase ZrW{sub 2}O{sub 8} above 550 °S. • ZrW{sub 2}O{sub 8} destructed at temperatures above 700 °S. - Abstract: This article discusses some peculiarities of the synthesis of ZrW{sub 2}O{sub 8} (1) using thermal decomposition of the precursor ZrW{sub 2}O{sub 7}((OH){sub 1.5},Cl{sub 0.5})·2H{sub 2}O (2) prepared by hydrothermal method. On hydrothermal synthesis of 2 the optimal concentration of hydrochloric acid in the reaction mixture is about 2.3 M. TG approach to determine the chemical composition of the precursor was suggested. It has been found that the precursor for the synthesis of zirconium tungstate has chemical formula 2. Thermal decomposition of the precursor 2 begins at 200 °S and affords an amorphous intermediate, which crystallizes as a cubic phase 1 above 550 °S with an exoeffect. The temperature of the beginning of the transition from amorphous to the crystalline state is 350 ± 25 °S.

  16. Ab initio Kinetics and Thermal Decomposition Mechanism of Mononitrobiuret and 1,5-Dinitrobiuret

    Science.gov (United States)

    2016-03-14

    energy barrier of 35 kcal/mol, and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol...Elimination of HNN(O)OH is also the primary channel involved in the thermal decomposition of DNB, which processes C2v symmetry . The rate coefficients... central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary

  17. Nanomechanical properties and thermal decomposition of Cu-Al2O3 composites for FGM applications

    Directory of Open Access Journals (Sweden)

    Koumoulos Elias P.

    2016-01-01

    Full Text Available It is widely reported that copper-alumina (Cu-Al2O3 nanocomposite materials exhibit high potential for use in structural applications in which enhanced mechanical characteristics are required. The investigation of Cu-Al2O3 nanocomposites which are to form a functionally graded material (FGM structure in terms of nanomechanical/structural integrity and thermal stability is still scarce. In this work, fully characterized nanosized Al2O3 powder has been incorporated in Cu matrix in various compositions (2, 5 and 10 wt.% of Al2O3 content. The produced composites were evaluated in terms of their morphology, structural analysis, thermal behavior, nanomechanical properties and their extent of viscoplasticity. The results reveal that all nanocomposites degrade at elevated temperatures; increased surface mass gain with decreasing Al2O3 content was observed, while no such difference of % mass gain in 5 and 10 wt.% of Al and Al2O3 content in Cu was observed. The increase of Al2O3 wt.% content results in thermal stability enhancement of the nanocomposites. The thermal decomposition process of the material is reduced in the presence of 10 wt.% of Al2O3 content. This result for the matrix decomposition can be explained by a decrease in the diffusion of oxygen and volatile degradation products throughout the composite material due to the incorporation of Al and Al2O3. The Al2O3 powder enhances the overall thermal stability of the system. All samples exhibited significant pile-up of the materials after nanoindentation testing. Increasing the wt.% of Al2O3 content was found to increase the creep deformation of the samples as well as the hardness and elastic modulus values.

  18. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Cavaignac, A.L.O. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Lima, R.J.C., E-mail: ricardo.lima.ufma@gmail.com [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Façanha Filho, P.F. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Moreno, A.J.D. [Coordenação de Ciências Naturais, Universidade Federal do Maranhão, Bacabal, MA 65700-000 (Brazil); Freire, P.T.C. [Departamento de Física, Universidade Federal do Ceará, Fortaleza, CE 60455-760 (Brazil)

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  19. Theoretical study of the pressure dependent rate constants of the thermal decomposition of β-propiolactone

    Directory of Open Access Journals (Sweden)

    Abolfazl Shiroudi

    2015-09-01

    Full Text Available A theoretical study of the thermal decomposition of β-propiolactone is carried out using ab initio molecular orbital (MO methods at the MP2/6-311+G∗∗ level and Rice–Ramsperger–Kassel–Marcus (RRKM theory. The reported experimental results showed that decomposition of β-propiolactone occurred by three competing homogeneous and first order reactions. For the three reactions, the calculation was also performed at the MP2/6-311+G∗∗ level of theory, as well as by single-point calculations at the B3LYP/6-311+G∗∗//MP2/6-311+G∗∗, and MP4/6-311+G∗∗//MP2/6-311+G∗∗ levels of theory. The fall-off pressures for the decomposition in these reactions are found to be 2.415, 9.423 × 10−2 and 3.676 × 10−3 mmHg, respectively.

  20. Validation of Heat Transfer Thermal Decomposition and Container Pressurization of Polyurethane Foam.

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Sarah Nicole; Dodd, Amanda B.; Larsen, Marvin E.; Suo-Anttila, Jill M.; Erickson, Kenneth L

    2014-09-01

    Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. In fire environments, gas pressure from thermal decomposition of polymers can cause mechanical failure of sealed systems. In this work, a detailed uncertainty quantification study of PMDI-based polyurethane foam is presented to assess the validity of the computational model. Both experimental measurement uncertainty and model prediction uncertainty are examined and compared. Both the mean value method and Latin hypercube sampling approach are used to propagate the uncertainty through the model. In addition to comparing computational and experimental results, the importance of each input parameter on the simulation result is also investigated. These results show that further development in the physics model of the foam and appropriate associated material testing are necessary to improve model accuracy.

  1. Kinetic Study of anti-HIV drugs by Thermal Decomposition Analysis: A Multilayer Artificial Neural Network Propose

    CERN Document Server

    Ferreira, B D L; Sebastião, R C O; Yoshida, M I; Mussel, W N; Fialho, S L; Barbosa, J

    2016-01-01

    Kinetic study by thermal decomposition of antiretroviral drugs, Efavirenz (EFV) and Lamivudine (3TC), usually present in the HIV cocktail, can be done by individual adjustment of the solid decomposition models. However, in some cases unacceptable errors are found using this methodology. To circumvent this problem, here is proposed to use a multilayer perceptron neural network (MLP), with an appropriate algorithm, which constitutes a linearization of the network by setting weights between the input layer and the intermediate one and the use of Kinetic models as activation functions of neurons in the hidden layer. The interconnection weights between that intermediate layer and output layer determines the contribution of each model in the overall fit of the experimental data. Thus, the decomposition is assumed to be a phenomenon that can occur following different kinetic processes. In the investigated data, the kinetic thermal decomposition process was best described by R1 and D4 model for all temperatures to EF...

  2. Synthesis, characterization and thermal decomposition of poly(decamethylene 2,6-naphthalamide

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available A novel engineering plastic, poly(decamethylene 2,6-naphthalamide (PA10N was prepared via a reaction of 2,6-naphthalene dicarboxylic acid and 1,10-decanediamine. The structure of synthesized PA10N was characterized by elemental analysis, Fourier transform infrared (FT-IR spectroscopy and proton nuclear magnetic resonance (1H-NMR. The thermal behavior was determined by differential scanning calorimetry (DSC, thermo-gravimetric analysis (TGA and dynamic mechanical analysis (DMA. Melting temperature (Tm, glass transition temperature (Tg and decomposition temperature (Td of PA10N are 320, 144 and 495°C, respectively. The solubility, water-absorbing capacity, and mechanical properties of PA10N have also been investigated. Pyrolysis products and thermal decomposition mechanism of PA10N were analyzed by flash pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS. The results show that the heat resistance and mechanical properties of PA10N are near to those of poly(nonamethylene terephthalamide (PA9T, and PA10N is a promising heat-resistant and processable engineering plastic.

  3. Investigation of thermodynamic parameters in the thermal decomposition of plastic waste-waste lube oil compounds.

    Science.gov (United States)

    Kim, Yong Sang; Kim, Young Seok; Kim, Sung Hyun

    2010-07-01

    Thermal decomposition properties of plastic waste-waste lube oil compounds were investigated under nonisothermal conditions. Polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) were selected as representative household plastic wastes. A plastic waste mixture (PWM) and waste lube oil (WLO) were mixed with mixing ratios of 33, 50, and 67 (w/w) % on a PWM weight basis, and thermogravimetric (TG) experiments were performed from 25 to 600 degrees C. The Flynn-Wall method and the Ozawa-Flynn-Wall method were used for analyses of thermodynamic parameters. In this study, activation energies of PWM/WLO compounds ranged from 73.4 to 229.6 kJ/mol between 0.2 and 0.8 of normalized mass conversions, and the 50% PWM/WLO compound had lower activation energies and enthalpies among the PWM/WLO samples at each mass conversion. At the point of maximum differential mass conversion, the analyzed activation energies, enthalpies, entropies, and Gibbs free energies indicated that mixing PWM and WLO has advantages in reducing energy to decrease the degree of disorder. However, no difference in overall energy that would require overcoming both thermal decomposition reactions and degree of disorder was observed among PWM/WLO compounds under these experimental conditions.

  4. In Situ Thermal Decomposition of Exfoliated Two-Dimensional Black Phosphorus.

    Science.gov (United States)

    Liu, Xiaolong; Wood, Joshua D; Chen, Kan-Sheng; Cho, EunKyung; Hersam, Mark C

    2015-03-05

    With a semiconducting band gap and high charge carrier mobility, two-dimensional (2D) black phosphorus (BP)—often referred to as phosphorene—holds significant promise for next generation electronics and optoelectronics. However, as a 2D material, it possesses a higher surface area to volume ratio than bulk BP, suggesting that its chemical and thermal stability will be modified. Herein, an atomic-scale microscopic and spectroscopic study is performed to characterize the thermal degradation of mechanically exfoliated 2D BP. From in situ scanning/transmission electron microscopy, decomposition of 2D BP is observed to occur at ∼400 °C in vacuum, in contrast to the 550 °C bulk BP sublimation temperature. This decomposition initiates via eye-shaped cracks along the [001] direction and then continues until only a thin, amorphous red phosphorus like skeleton remains. In situ electron energy loss spectroscopy, energy-dispersive X-ray spectroscopy, and energy-loss near-edge structure changes provide quantitative insight into this chemical transformation process.

  5. Synthesis of seaweed based carbon acid catalyst by thermal decomposition of ammonium sulfate for biodiesel production

    Science.gov (United States)

    Ee, Tang Zo; Lim, Steven; Ling, Pang Yean; Huei, Wong Kam; Chyuan, Ong Hwai

    2017-04-01

    Experiment was carried out to study the feasibility of biomass derived solid acid catalyst for the production of biodiesel using Palm Fatty Acid Distillate (PFAD). Malaysia indigenous seaweed was selected as the biomass to be carbonized as the catalyst support. Sulfonation of seaweed based carbon material was carried out by thermal decomposition of ammonium sulfate, (NH4)2SO4. The effects of carbonization temperature at 200 to 600°C on the catalyst physical and chemical properties were studied. The effect of reaction parameters on the fatty acid methyl ester (FAME) yield was studied by varying the concentration of ammonium sulfate (5.0 to 40.0 w/v%) and thermal decomposition time (15 to 90 min). Characterizations of catalyst were carried out to study the catalyst surface morphology with Scanning Electron Microscope (SEM), acid density with back titration and functional group attached with FT-IR. Results showed that when the catalyst sulfonated with 10.0 w/v% ammonium sulfate solution and heated to 235°C for 30 min, the highest FAME yield achieved was 23.7% at the reaction condition of 5.0 wt.% catalyst loading, esterification time of 4 h, methanol to PFAD molar ratio of 20:1 at 100°C reaction temperature.

  6. Thermal decomposition of sugarcane straw, kinetics and heat of reaction in synthetic air.

    Science.gov (United States)

    Rueda-Ordóñez, Yesid Javier; Tannous, Katia

    2016-07-01

    The aim of this work was to analyze the thermal decomposition, kinetics and heat of reaction of sugarcane straw in synthetic air by thermogravimetry (TG) and differential scanning calorimetry (DSC). The TG and DSC experiments were carried out using heating rates of 2.5°C/min, 5°C/min, and 10°C/min, and particle diameter of 0.250mm. In the study of the smoldering reaction were identified three consecutive stages, drying, oxidative pyrolysis, and combustion. Thus, the kinetic pathway was composed by six independent parallel reactions, three for each stage after drying, in which the activation energies were 176, 313, 150, 80, 150, and 100kJ/mol. The heat of reaction in synthetic air was completely exothermic releasing 8MJ/kg. The modeled curves of thermal decomposition of sugarcane straw presented good agreement with experimental data. Then, the kinetic parameters obtained could be used to analyze different processes involving smoldering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. CFD SIMULATION FOR DEMILITARIZATION OF RDX IN A ROTARY KILN BY THERMAL DECOMPOSITION

    Directory of Open Access Journals (Sweden)

    SI H. LEE

    2017-06-01

    Full Text Available Demilitarization requires the recovery and disposal of obsolete ammunition and explosives. Since open burning/detonation of hazardous waste has caused serious environmental and safety problems, thermal decomposition has emerged as one of the most feasible methods. RDX is widely used as a military explosive due to its high melting temperature and detonation power. In this work, the feasible conditions under which explosives can be safely incinerated have been investigated via a rotary kiln simulation. To solve this problem, phase change along with the reactions of RDX has been incisively analyzed. A global reaction mechanism consisting of condensed phase and gas phase reactions are used in Computational Fluid Dynamics simulation. User Defined Functions in FLUENT is utilized in this study to inculcate the reactions and phase change into the simulation. The results divulge the effect of temperature and the varying amounts of gas produced in the rotary kiln during the thermal decomposition of RDX. The result leads to the prospect of demilitarizing waste explosives to avoid the possibility of detonation.

  8. Research on the Thermal Decomposition Reaction Kinetics and Mechanism of Pyridinol-Blocked Isophorone Diisocyanate

    Directory of Open Access Journals (Sweden)

    Sen Guo

    2016-02-01

    Full Text Available A series of pyridinol-blocked isophorone isocyanates, based on pyridinol including 2-hydroxypyridine, 3-hydroxypyridine, and 4-hydroxypyridine, was synthesized and characterized by 1H-NMR, 13C-NMR, and FTIR spectra. The deblocking temperature of blocked isocyanates was established by thermo-gravimetric analysis (TGA, differential scanning calorimetry (DSC, and the CO2 evaluation method. The deblocking studies revealed that the deblocking temperature was increased with pyridinol nucleophilicity in this order: 3-hydroxypyridine > 4-hydroxypyridine > 2-hydroxypyridine. The thermal decomposition reaction of 4-hydroxypyridine blocked isophorone diisocyanate was studied by thermo-gravimetric analysis. The Friedman–Reich–Levi (FRL equation, Flynn–Wall–Ozawa (FWO equation, and Crane equation were utilized to analyze the thermal decomposition reaction kinetics. The activation energy calculated by FRL method and FWO method was 134.6 kJ·mol−1 and 126.2 kJ·mol−1, respectively. The most probable mechanism function calculated by the FWO method was the Jander equation. The reaction order was not an integer because of the complicated reactions of isocyanate.

  9. An investigation on the modelling of kinetics of thermal decomposition of hazardous mercury wastes.

    Science.gov (United States)

    Busto, Yailen; M G Tack, Filip; Peralta, Luis M; Cabrera, Xiomara; Arteaga-Pérez, Luis E

    2013-09-15

    The kinetics of mercury removal from solid wastes generated by chlor-alkali plants were studied. The reaction order and model-free method with an isoconversional approach were used to estimate the kinetic parameters and reaction mechanism that apply to the thermal decomposition of hazardous mercury wastes. As a first approach to the understanding of thermal decomposition for this type of systems (poly-disperse and multi-component), a novel scheme of six reactions was proposed to represent the behaviour of mercury compounds in the solid matrix during the treatment. An integration-optimization algorithm was used in the screening of nine mechanistic models to develop kinetic expressions that best describe the process. The kinetic parameters were calculated by fitting each of these models to the experimental data. It was demonstrated that the D₁-diffusion mechanism appeared to govern the process at 250°C and high residence times, whereas at 450°C a combination of the diffusion mechanism (D₁) and the third order reaction mechanism (F3) fitted the kinetics of the conversions. The developed models can be applied in engineering calculations to dimension the installations and determine the optimal conditions to treat a mercury containing sludge. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Catalyst Effects of Nanometer CuCr2O4 on the Thermal Decomposition of TEGDN Propellant

    Science.gov (United States)

    Yan, Shi; Kou, Chenxia; Li, Yanchun; Cheng, Yi

    2012-04-01

    The catalyst effects of nanometer CuCr2O4 on the thermal decomposition of triethyleneglycol dinitrate (TEGDN) propellant were investigated using thermogravimetric analysis, differential scanning calorimetry, mass spectrometry, and Fourier transform infrared spectroscopy. The Ozawa equation and step integral equation were used to calculate the activation energy. The results showed that the thermal decomposition reaction of TEGDN propellant can be seen as two reactions. Nanometer CuCr2O4 added in TEGDN propellant reduced the activation energy of the second reaction step; therefore, the second reaction step was sped up. Mass spectrometry, Fourier transform infrared spectrometry and the combustion residue analysis results also supported this conclusion.

  11. Thermal decomposition rate of MgCO3 as an inorganic astrobiological matrix in meteorites

    Science.gov (United States)

    Bisceglia, E.; Longo, G. Micca; Longo, S.

    2017-04-01

    Carbonate minerals, likely of hydrothermal origins and included into orthopyroxenite, have been extensively studied in the ALH84001 meteorite. In this meteorite, nanocrystals comparable with those produced by magnetotactic bacteria have been found into a carbonate matrix. This leads naturally to a discussion of the role of such carbonates in panspermia theories. In this context, the present work sets the basis of a criterion to evaluate whether a carbonate matrix in a meteor entering a planetary atmosphere would be able to reach the surface. As a preliminary step, the composition of carbonate minerals in the ALH84001 meteorite is reviewed; in view of the predominance of Mg in these carbonates, pure magnesite (MgCO3) is proposed as a mineral model. This mineral is much more sensitive to high temperatures reached during an entry process, compared with silicates, due to facile decomposition into MgO and gaseous carbon dioxide (CO2). A most important quantity for further studies is therefore the decomposition rate expressed as CO2 evaporation rate J (molecules/m2 s). An analytical expression for J(T) is given using the Langmuir law, based on CO2 pressure in equilibrium with MgCO3 and MgO at the surface temperature T. Results suggest that carbonate minerals rich in magnesium may offer much better thermal protection to embedded biological matter than silicates and significantly better than limestone, which was considered in previous studies, in view of the heat absorbed by their decomposition even at moderate temperatures. This first study can be extended in the future to account for more complex compositions, including Fe and Ca.

  12. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

    Science.gov (United States)

    Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

    2015-11-28

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

  13. The thermal decomposition of the benzyl radical in a heated micro-reactor. I. Experimental findings

    Science.gov (United States)

    Buckingham, Grant T.; Ormond, Thomas K.; Porterfield, Jessica P.; Hemberger, Patrick; Kostko, Oleg; Ahmed, Musahid; Robichaud, David J.; Nimlos, Mark R.; Daily, John W.; Ellison, G. Barney

    2015-01-01

    The pyrolysis of the benzyl radical has been studied in a set of heated micro-reactors. A combination of photoionization mass spectrometry (PIMS) and matrix isolation infrared (IR) spectroscopy has been used to identify the decomposition products. Both benzyl bromide and ethyl benzene have been used as precursors of the parent species, C6H5CH2, as well as a set of isotopically labeled radicals: C6H5CD2, C6D5CH2, and C6H513CH2. The combination of PIMS and IR spectroscopy has been used to identify the earliest pyrolysis products from benzyl radical as: C5H4=C=CH2, H atom, C5H4—C ≡ CH, C5H5, HCCCH2, and HC ≡ CH. Pyrolysis of the C6H5CD2, C6D5CH2, and C6H513CH2 benzyl radicals produces a set of methyl radicals, cyclopentadienyl radicals, and benzynes that are not predicted by a fulvenallene pathway. Explicit PIMS searches for the cycloheptatrienyl radical were unsuccessful, there is no evidence for the isomerization of benzyl and cycloheptatrienyl radicals: C6H5CH2⇋C7H7. These labeling studies suggest that there must be other thermal decomposition routes for the C6H5CH2 radical that differ from the fulvenallene pathway.

  14. Thermal Decomposition Study on CuInSe2 Single Crystals

    Science.gov (United States)

    Chauhan, Sanjaysinh M.; Chaki, Sunil H.; Deshpande, M. P.; Malek, Tasmira J.; Tailor, J. P.

    2018-01-01

    The thermal analysis of the chemical vapor transport (CVT)-grown CuInSe2 single crystals was carried out by recording the thermogravimetric, differential thermogravimetric and differential thermal analysis curves. All the three thermo-curves were recorded simultaneously by thermal analyzer in the temperature range of ambient to 1080 K in inert nitrogen atmosphere. The thermo-curves were recorded for four heating rates of 5 K \\cdot min^{-1}, 10 K \\cdot min^{-1}, 15 K \\cdot min^{-1} and 20 K \\cdot min^{-1}. The TG curve analysis showed negligible mass loss in the temperature range of ambient to 600 K, stating the sample material to be thermally stable in this temperature range. Above 601 K to the temperature of 1080 K, the sample showed continuous mass loss. The DTG curves showed two peaks in the temperature range of 601 K to 1080 K. The corresponding DTA showed initial minor exothermic nature followed by endothermic nature up to nearly 750 K and above it showed exothermic nature. The initial exothermic nature is due to absorbed water converting to water vapor, whereas the endothermic nature states the absorption of heat by the sample up to nearly 950 K. Above nearly 950 K the exothermic nature is due to the decomposition of sample material. The absorption of heat in the endothermic region is substantiated by corresponding weight loss in TG. The thermal kinetic parameters of the CVT-grown CuInSe2 single crystals were determined employing the non-mechanistic Kissinger relation. The determined kinetic parameters support the observations of the thermo-curves.

  15. Thermal stability and mechanism of decomposition of emulsion explosives in the presence of pyrite.

    Science.gov (United States)

    Xu, Zhi-Xiang; Wang, Qian; Fu, Xiao-Qi

    2015-12-30

    The reaction of emulsion explosives (ammonium nitrate) with pyrite was studied using techniques of TG-DTG-DTA. TG-DSC-MS was also used to analyze samples thermal decomposition process. When a mixture of pyrite and emulsion explosives was heated at a constant heating rate of 10K/min from room temperature to 350°C, exothermic reactions occurred at about 200°C. The essence of reaction between emulsion explosives and pyrite is the reaction between ammonium nitrate and pyrite. Emulsion explosives have excellent thermal stability but it does not mean it showed the same excellent thermal stability when pyrite was added. Package emulsion explosives were more suitable to use in pyrite shale than bulk emulsion explosives. The exothermic reaction was considered to take place between ammonium nitrate and pyrite where NO, NO2, NH3, SO2 and N2O gases were produced. Based on the analysis of the gaseous, a new overall reaction was proposed, which was thermodynamically favorable. The results have significant implication in the understanding of stability of emulsion explosives in reactive mining grounds containing pyrite minerals. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Room temperature and thermal decomposition of magnesium hydride/deuteride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ares, J.R.; Leardini, F.; Bodega, J.; Macia, M.D.; Diaz-Chao, P.; Ferrer, I.J.; Fernandez, J.F.; Sanchez, C. [Universidad Autonoma de Madrid (Spain). Lab. de Materiales de Interes en Energias Renovables

    2010-07-01

    Magnesium hydride (MgH{sub 2}) can be considered an interesting material to store hydrogen as long as two main drawbacks were solved: (i) its high stability and (ii) slow (de)hydriding kinetics. In that context, magnesium hydride films are an excellent model system to investigate the influence of structure, morphology and dimensionality on kinetic and thermodynamic properties. In the present work, we show that desorption mechanism of Pd-capped MgH{sub 2} at room temperature is controlled by a bidimensional interphase mechanism and a similar rate step limiting mechanism is observed during thermal decomposition of MgH{sub 2}. This mechanism is different to that occurring in bulk MgH{sub 2} (nucleation and growth) and obtained activation energies are lower than those reported in bulk MgH{sub 2}. We also investigated the Pd-capping properties upon H-absorption/desorption by means of RBS and isotope experiments. (orig.)

  17. Thermal Analysis of porous fin with uniform magnetic field using Adomian decomposition Sumudu transform method

    Science.gov (United States)

    Patel, Trushit; Meher, Ramakanta

    2017-09-01

    In this paper, we consider a Roseland approximation to radiate heat transfer, Darcy's model to simulate the flow in porous media and finite-length fin with insulated tip to study the thermal performance and to predict the temperature distribution in a vertical isothermal surface. The energy balance equations of the porous fin with several temperature dependent properties are solved using the Adomian Decomposition Sumudu Transform Method (ADSTM). The effects of various thermophysical parameters, such as the convection-conduction parameter, Surface-ambient radiation parameter, Rayleigh numbers and Hartman number are determined. The results obtained from the ADSTM are further compared with the fourth-fifth order Runge-Kutta-Fehlberg method and Least Square Method(LSM) (Hoshyar et al. 2016 ) to determine the accuracy of the solution.

  18. Studies on Thermal Decomposition of Aluminium Sulfate to Produce Alumina Nano Structure

    Directory of Open Access Journals (Sweden)

    M. Jafar-Tafreshi

    2012-12-01

    Full Text Available Aluminum sulfate nano structures have been prepared by solution combustion synthesis using aluminum nitrate nonahydrate (Al(NO33.9H2O and ammonium sulfate ((NH42SO4. The resultant aluminum sulfate nano structures were calcined at different temperatures to study thermal  decomposition of aluminum sulfate. The crystallinity and phase of  the as-synthesized and calcined samples were characterized by both X- ray diffraction and FTIR measurements. These two analyses determined the temperature at which the aluminum sulfate is converted to γ-alumina nano particles. The specific surface area and pore size distribution for  γ-alumina nano particles were determined by BET measurement. TEM measurement confirmed the size of the particles obtained by XRD and BET analyses.

  19. Thermal decomposition of wood in oxidizing atmosphere: A kinetic study from non-isothermal TG experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, T.; Rodriguez-Maroto, F.G.; Rodriguez, J.J. (Univ. of Malaga (Spain))

    1991-11-22

    The kinetics of thermal decomposition of four wood species in oxygen-bearing atmospheres of 5, 10 and 20% molar O{sub 2} concentrations have been studied from temperature-programmed experiments carried out at 5, 10 and 20 K min{sup {minus}1} heating rate. Devolatilization as well as combustion of the reamining solid have been considered to analyze the weight loss curves. The homogeneous volume reaction (VR) model has been used to describe devolatilization, whereas for solid combustion the grain model has been also checked. A two-stage approach has been used to fit the conversion-time curves and to derive the corresponding apparent kinetic parameters. The VR/VR (pyrolysis/combustion) combination provided a better description of the experimental {alpha}-t curves than the VR/grain combination. Holm oak and cork oak showed very close reactivities, whereas some differences were observed for aleppo pine and eucalyptus. 6 figs. 8 tabs., 20 refs.

  20. Fabrication of Lotus-Type Porous Aluminum through Thermal Decomposition Method

    Science.gov (United States)

    Kim, S. Y.; Park, J. S.; Nakajima, H.

    2009-04-01

    Lotus-type porous aluminum with cylindrical pores was fabricated by unidirectional solidification through thermal decomposition of calcium hydroxide, sodium bicarbonate, or titanium hydride. The pore-forming gas decomposed from calcium hydroxide, sodium bicarbonate, and titanium hydride is identified as hydrogen. The elongated pores are evolved due to the solubility gap between liquid and solid when the melt dissolving hydrogen is solidified unidirectionally. The porosity of lotus aluminum is as high as 20 pct despite the type of the compounds. The pore size decreases and the pore density increases with increasing amount of calcium hydroxide, which is explained by an increase in the number of pore nucleation sites. The porosity and pore size in lotus aluminum fabricated using calcium hydroxide decrease with increasing argon pressure, which is explained by Boyle’s law. It is suggested that this fabrication method is simple and safe, which makes it superior to the conventional technique using high-pressure hydrogen gas.

  1. Chemical kinetics on thermal decompositions of cumene hydroperoxide in cumene studied by calorimetry: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Duh, Yih-Shing, E-mail: yihshingduh@yahoo.com.tw [Department of Occupation Safety and Health, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, 35664, Taiwan, ROC (China); Department of Safety, Health and Environmental Engineering, National United University, No. 1 Lien-Da, Miaoli, 36052, Taiwan, ROC (China)

    2016-08-10

    Highlights: • Chemical kinetics on thermal decompositions of CHP are conducted and summarized. • Kinetics agrees well between data from DSC and adiabatic calorimetry. • Ea is determined to be about 120 kJ mol{sup −1} by various calorimetry. • LogA (A in s{sup −1}) is determined to be about 11.8 by various calorimetry. - Abstract: Study on chemical kinetics related to the thermal decomposition of cumene hydoperoxide (CHP) in cumene is summarized in this work. It is of great importance to gather and compare the differences between these kinetic parameters for further substantial applications in the chemical industry and process safety. CHP has been verified to possess an autocatalytic behavior by using microcalorimetry (such as TAM and C-80) operated at isothermal mode in the temperature range from 70 °C to 120 °C. However, it exhibits a reaction of n-th order detected by non-isothermal DSC scanning and adiabatic calorimeter. By the isothermal aging tests, activation energy and frequency factor in logA(s{sup −1}) were averaged to be (117.3 ± 5.9) kJ mol{sup −1}and (11.4 ± 0.3), respectively. Kinetic parameters acquired from data of interlaboratories by using heat-flow calorimetry, the averaged activation energy and frequency factor in logA(s{sup −1}) were (119.3 ± 11.3) kJ mol{sup −1}and (12.0 ± 0.2), respectively. On the analogy of results from adiabatic calorimetry, the activation energy and frequency factor in logA(s{sup −1}) were respectively averaged to be (122.4 ± 9.2) kJ mol{sup −1}and (11.8 ± 0.8). Five sets of kinetic models in relation to autocatalytic reactions are collected and discussed as well.

  2. Synthesis of CNTs/CuO and its catalytic performance on the thermal decomposition of ammonium perchlorate

    Directory of Open Access Journals (Sweden)

    Ping Cui

    2016-05-01

    Full Text Available Copper oxide (CuO nanoparticles were successfully deposited on carbon nanotubes’ (CNTs surface via complex-precipitation method, the nanocomposite was characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, X-ray powder diffraction (XRD, Raman spectroscopy, Fourier transform infrared (FT-IR and Brunauer–Emmett–Teller (BET. The catalytic performance of CNTs/CuO on ammonium perchlorate (AP decomposition was analyzed by differential thermal analyzer (DTA, the DTA results showed its excellent catalytic effect on AP decomposition, as 8 wt.% CNTs/CuO was added in AP, the second exothermic peak temperature decreased by 158 °C. Such composite may be a promising candidate for catalyzing the AP thermal decomposition.

  3. Analysis of the Compounds from the BTEX Group, Emitted During Thermal Decomposition of Alkyd Resin

    Directory of Open Access Journals (Sweden)

    M. Kubecki

    2012-09-01

    Full Text Available Suitability of the given binding agent for the moulding sands preparation depends on the one hand on the estimation of technological properties of the sand and the mould made of it and the obtained casting quality and on the other hand on the assessment of this sand influence on the natural and working environment. Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. If in the initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin (phenol-formaldehyde, urea, furfuryl, urea–furfuryl, alkyd under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene, and also polycyclic aromatic hydrocarbons (PAH can be formed and released.The aim of the study was the development of the method, selection of analytical methods and the determination of optimal conditionsof formation compounds from the BTEX group. An emission of these components constitutes one of the basic criteria of the harmfulnessassessment of binders applied for moulding and core sands. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 5000C – 13000C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. Within investigations the minimal amount of adsorbent necessary for the adsorption of compounds released during the decomposition of the resin sample of a mass app. 15 mg was selected. Also the minimal amount of solvent needed for

  4. COMPOSITE POLYMERICADDITIVESDESIGNATED FORCONCRETEMIXES BASED ONPOLYACRYLATES, PRODUCTS OF THERMAL DECOMPOSITION OF POLYAMIDE-6 AND LOW-MOLECULAR POLYETHYLENE

    Directory of Open Access Journals (Sweden)

    Polyakov Vyacheslav Sergeevich

    2012-07-01

    4 the optimal composite additive that increases the time period of stiffening of the cement grout , improves the water resistance and the compressive strength of concrete, represents the composition of polyacrylates and polymethacrylates, products of thermal decomposition of polyamide-6 and low-molecular polyethylene in the weight ratio of 1:1:0.5.

  5. The glassy behaviour of poorly crystalline Fe2O3 nanorods obtained by thermal decomposition of ferrous oxalate

    Czech Academy of Sciences Publication Activity Database

    Perović, M.; Kusigerski, V.; Mrakovic, A.; Spasojevic, V.; Blanusa, J.; Nikolic, V.; Schneeweiss, Oldřich; David, Bohumil; Pizúrová, Naděžda

    2015-01-01

    Roč. 26, č. 11 (2015), Art. n. 115705 ISSN 0957-4484 Institutional support: RVO:68081723 Keywords : Thermal decomposition * Nanorods * Iron oxide * Spin glass like * Memory effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.573, year: 2015

  6. Thermal stability and mechanism of decomposition of emulsion explosives in the presence of pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhi-Xiang; Wang, Qian [School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Fu, Xiao-Qi, E-mail: xzx19820708@163.com [School of Chemistry and Chemical Engineering, Jiangsu University Zhenjiang 212013 (China)

    2015-12-30

    Highlights: • An exothermic reaction occurs at about 200 °C between pyrite and ammonium nitrate (emulsion explosives). • The essence of reaction between emulsion explosives and pyrite is reaction between ammonium nitrate and pyrite. • The excellent thermal stability of emulsion explosives does not mean it was also showed when pyrite was added. • A new overall reaction has been proposed as: • 14FeS{sub 2}(s) + 91NH{sub 4}NO{sub 3}(s) → 52NO(g) + 26SO{sub 2}(g) + 6Fe{sub 2}O{sub 3}(s) + 78NH{sub 3}(g) + 26N{sub 2}O(g) + 2FeSO{sub 4}(s) + 65H{sub 2}O(g). - Abstract: The reaction of emulsion explosives (ammonium nitrate) with pyrite was studied using techniques of TG-DTG-DTA. TG–DSC–MS was also used to analyze samples thermal decomposition process. When a mixture of pyrite and emulsion explosives was heated at a constant heating rate of 10 K/min from room temperature to 350 °C, exothermic reactions occurred at about 200 °C. The essence of reaction between emulsion explosives and pyrite is the reaction between ammonium nitrate and pyrite. Emulsion explosives have excellent thermal stability but it does not mean it showed the same excellent thermal stability when pyrite was added. Package emulsion explosives were more suitable to use in pyrite shale than bulk emulsion explosives. The exothermic reaction was considered to take place between ammonium nitrate and pyrite where NO, NO{sub 2}, NH{sub 3}, SO{sub 2} and N{sub 2}O gases were produced. Based on the analysis of the gaseous, a new overall reaction was proposed, which was thermodynamically favorable. The results have significant implication in the understanding of stability of emulsion explosives in reactive mining grounds containing pyrite minerals.

  7. Plasmonic Thermal Decomposition/Digestion of Proteins: A Rapid On-Surface Protein Digestion Technique for Mass Spectrometry Imaging.

    Science.gov (United States)

    Zhou, Rong; Basile, Franco

    2017-09-05

    A method based on plasmon surface resonance absorption and heating was developed to perform a rapid on-surface protein thermal decomposition and digestion suitable for imaging mass spectrometry (MS) and/or profiling. This photothermal process or plasmonic thermal decomposition/digestion (plasmonic-TDD) method incorporates a continuous wave (CW) laser excitation and gold nanoparticles (Au-NPs) to induce known thermal decomposition reactions that cleave peptides and proteins specifically at the C-terminus of aspartic acid and at the N-terminus of cysteine. These thermal decomposition reactions are induced by heating a solid protein sample to temperatures between 200 and 270 °C for a short period of time (10-50 s per 200 μm segment) and are reagentless and solventless, and thus are devoid of sample product delocalization. In the plasmonic-TDD setup the sample is coated with Au-NPs and irradiated with 532 nm laser radiation to induce thermoplasmonic heating and bring about site-specific thermal decomposition on solid peptide/protein samples. In this manner the Au-NPs act as nanoheaters that result in a highly localized thermal decomposition and digestion of the protein sample that is independent of the absorption properties of the protein, making the method universally applicable to all types of proteinaceous samples (e.g., tissues or protein arrays). Several experimental variables were optimized to maximize product yield, and they include heating time, laser intensity, size of Au-NPs, and surface coverage of Au-NPs. Using optimized parameters, proof-of-principle experiments confirmed the ability of the plasmonic-TDD method to induce both C-cleavage and D-cleavage on several peptide standards and the protein lysozyme by detecting their thermal decomposition products with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The high spatial specificity of the plasmonic-TDD method was demonstrated by using a mask to digest designated sections of

  8. Effect of Copper Oxide, Titanium Dioxide, and Lithium Fluoride on the Thermal Behavior and Decomposition Kinetics of Ammonium Nitrate

    Science.gov (United States)

    Vargeese, Anuj A.; Mija, S. J.; Muralidharan, Krishnamurthi

    2014-07-01

    Ammonium nitrate (AN) is crystallized along with copper oxide, titanium dioxide, and lithium fluoride. Thermal kinetic constants for the decomposition reaction of the samples were calculated by model-free (Friedman's differential and Vyzovkins nonlinear integral) and model-fitting (Coats-Redfern) methods. To determine the decomposition mechanisms, 12 solid-state mechanisms were tested using the Coats-Redfern method. The results of the Coats-Redfern method show that the decomposition mechanism for all samples is the contracting cylinder mechanism. The phase behavior of the obtained samples was evaluated by differential scanning calorimetry (DSC), and structural properties were determined by X-ray powder diffraction (XRPD). The results indicate that copper oxide modifies the phase transition behavior and can catalyze AN decomposition, whereas LiF inhibits AN decomposition, and TiO2 shows no influence on the rate of decomposition. Possible explanations for these results are discussed. Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Energetic Materials to view the free supplemental file.

  9. High-energy coordination polymers (CPs) exhibiting good catalytic effect on the thermal decomposition of ammonium dinitramide

    Science.gov (United States)

    Li, Xin; Han, Jing; Zhang, Sheng; Zhai, Lianjie; Wang, Bozhou; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Gao, Shengli

    2017-09-01

    High-energy coordination polymers (CPs) not only exhibit good energetic performances but also have a good catalytic effect on the thermal decomposition of energetic materials. In this contribution, two high-energy CPs Cu2(DNBT)2(CH3OH)(H2O)3·3H2O (1) and [Cu3(DDT)2(H2O)2]n (2) (H2DNBT = 3,3‧-dinitro-5,5‧-bis(1H-1,2,4-triazole and H3DDT = 4,5-bis(1H-tetrazol-5-yl)-2H-1,2,3-triazole) were synthesized and structurally characterized. Furthermore, 1 was thermos-dehydrated to produce Cu2(DNBT)2(CH3OH)(H2O)3 (1a). The thermal decomposition kinetics of 1, 1a and 2 were studied by Kissinger's method and Ozawa's method. Thermal analyses and sensitivity tests show that all compounds exhibit high thermal stability and low sensitivity for external stimuli. Meanwhile, all compounds have large positive enthalpy of formation, which are calculated as being (1067.67 ± 2.62) kJ mol-1 (1), (1464.12 ± 3.12) kJ mol-1 (1a) and (3877.82 ± 2.75) kJ mol-1 (2), respectively. The catalytic effects of 1a and 2 on the thermal decomposition of ammonium dinitramide (ADN) were also investigated.

  10. The thermal decomposition of the benzyl radical in a heated micro-reactor. I. Experimental findings

    Energy Technology Data Exchange (ETDEWEB)

    Buckingham, Grant T.; Ormond, Thomas K. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Porterfield, Jessica P.; Ellison, G. Barney [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Hemberger, Patrick [Molecular Dynamics Group, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Kostko, Oleg; Ahmed, Musahid [Chemical Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720 (United States); Robichaud, David J.; Nimlos, Mark R. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Daily, John W. [Department of Mechanical Engineering, Center for Combustion and Environmental Research,University of Colorado, Boulder, Colorado 80309-0427 (United States)

    2015-01-28

    The pyrolysis of the benzyl radical has been studied in a set of heated micro-reactors. A combination of photoionization mass spectrometry (PIMS) and matrix isolation infrared (IR) spectroscopy has been used to identify the decomposition products. Both benzyl bromide and ethyl benzene have been used as precursors of the parent species, C{sub 6}H{sub 5}CH{sub 2}, as well as a set of isotopically labeled radicals: C{sub 6}H{sub 5}CD{sub 2}, C{sub 6}D{sub 5}CH{sub 2}, and C{sub 6}H{sub 5}{sup 13}CH{sub 2}. The combination of PIMS and IR spectroscopy has been used to identify the earliest pyrolysis products from benzyl radical as: C{sub 5}H{sub 4}=C=CH{sub 2}, H atom, C{sub 5}H{sub 4}—C ≡ CH, C{sub 5}H{sub 5}, HCCCH{sub 2}, and HC ≡ CH. Pyrolysis of the C{sub 6}H{sub 5}CD{sub 2}, C{sub 6}D{sub 5}CH{sub 2}, and C{sub 6}H{sub 5}{sup 13}CH{sub 2} benzyl radicals produces a set of methyl radicals, cyclopentadienyl radicals, and benzynes that are not predicted by a fulvenallene pathway. Explicit PIMS searches for the cycloheptatrienyl radical were unsuccessful, there is no evidence for the isomerization of benzyl and cycloheptatrienyl radicals: C{sub 6}H{sub 5}CH{sub 2}⇋C{sub 7}H{sub 7}. These labeling studies suggest that there must be other thermal decomposition routes for the C{sub 6}H{sub 5}CH{sub 2} radical that differ from the fulvenallene pathway.

  11. Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen.

    Science.gov (United States)

    Unni, Mythreyi; Uhl, Amanda M; Savliwala, Shehaab; Savitzky, Benjamin H; Dhavalikar, Rohan; Garraud, Nicolas; Arnold, David P; Kourkoutis, Lena F; Andrew, Jennifer S; Rinaldi, Carlos

    2017-02-28

    Decades of research focused on size and shape control of iron oxide nanoparticles have led to methods of synthesis that afford excellent control over physical size and shape but comparatively poor control over magnetic properties. Popular synthesis methods based on thermal decomposition of organometallic precursors in the absence of oxygen have yielded particles with mixed iron oxide phases, crystal defects, and poorer than expected magnetic properties, including the existence of a thick "magnetically dead layer" experimentally evidenced by a magnetic diameter significantly smaller than the physical diameter. Here, we show how single-crystalline iron oxide nanoparticles with few defects and similar physical and magetic diameter distributions can be obtained by introducing molecular oxygen as one of the reactive species in the thermal decomposition synthesis. This is achieved without the need for any postsynthesis oxidation or thermal annealing. These results address a significant challenge in the synthesis of nanoparticles with predictable magnetic properties and could lead to advances in applications of magnetic nanoparticles.

  12. Comparative evaluation of thermal oxidative decomposition for oil-plant residues via thermogravimetric analysis: Thermal conversion characteristics, kinetics, and thermodynamics.

    Science.gov (United States)

    Chen, Jianbiao; Wang, Yanhong; Lang, Xuemei; Ren, Xiu'e; Fan, Shuanshi

    2017-11-01

    Thermal oxidative decomposition characteristics, kinetics, and thermodynamics of rape straw (RS), rapeseed meal (RM), camellia seed shell (CS), and camellia seed meal (CM) were evaluated via thermogravimetric analysis (TGA). TG-DTG-DSC curves demonstrated that the combustion of oil-plant residues proceeded in three stages, including dehydration, release and combustion of organic volatiles, and chars oxidation. As revealed by combustion characteristic parameters, the ignition, burnout, and comprehensive combustion performance of residues were quite distinct from each other, and were improved by increasing heating rate. The kinetic parameters were determined by Coats-Redfern approach. The results showed that the most possible combustion mechanisms were order reaction models. The existence of kinetic compensation effect was clearly observed. The thermodynamic parameters (ΔH, ΔG, ΔS) at peak temperatures were calculated through the activated complex theory. With the combustion proceeding, the variation trends of ΔH, ΔG, and ΔS for RS (RM) similar to those for CS (CM). Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Thermal Decomposition Mechanisms of Lignin Model Compounds: From Phenol to Vanillin

    Science.gov (United States)

    Scheer, Adam Michael

    Lignin is a complex, aromatic polymer abundant in cellulosic biomass (trees, switchgrass etc.). Thermochemical breakdown of lignin for liquid fuel production results in undesirable polycyclic aromatic hydrocarbons that lead to tar and soot byproducts. The fundamental chemistry governing these processes is not well understood. We have studied the unimolecular thermal decomposition mechanisms of aromatic lignin model compounds using a miniature SiC tubular reactor. Products are detected and characterized using time-of-flight mass spectrometry with both single photon (118.2 nm; 10.487 eV) and 1 + 1 resonance-enhanced multiphoton ionization (REMPI) as well as matrix isolation infrared spectroscopy. Gas exiting the heated reactor (300 K--1600 K) is subject to a free expansion after a residence time of approximately 100 micros. The expansion into vacuum rapidly cools the gas mixture and allows the detection of radicals and other highly reactive intermediates. By understanding the unimolecular fragmentation patterns of phenol (C6H5OH), anisole (C6H 5OCH3) and benzaldehyde (C6H5CHO), the more complicated thermocracking processes of the catechols (HO-C 6H4-OH), methoxyphenols (HO-C6H4-OCH 3) and hydroxybenzaldehydes (HO-C6H4-CHO) can be interpreted. These studies have resulted in a predictive model that allows the interpretation of vanillin, a complex phenolic ether containing methoxy, hydroxy and aldehyde functional groups. This model will serve as a guide for the pyrolyses of larger systems including lignin monomers such as coniferyl alcohol. The pyrolysis mechanisms of the dimethoxybenzenes (H3C-C 6H4-OCH3) and syringol, a hydroxydimethoxybenzene have also been studied. These results will aid in the understanding of the thermal fragmentation of sinapyl alcohol, the most complex lignin monomer. In addition to the model compound work, pyrolyisis of biomass has been studied via the pulsed laser ablation of poplar wood. With the REMPI scheme, aromatic lignin decomposition

  14. Effect of composting on the thermal decomposition behavior and kinetic parameters of pig manure-derived solid waste.

    Science.gov (United States)

    Dhyani, Vaibhav; Kumar Awasthi, Mukesh; Wang, Quan; Kumar, Jitendra; Ren, Xiuna; Zhao, Junchao; Chen, Hongyu; Wang, Meijing; Bhaskar, Thallada; Zhang, Zengqiang

    2017-12-27

    In this work, the influence of composting on the thermal decomposition behavior and decomposition kinetics of pig manure-derived solid wastes was analyzed using thermogravimetry. Wheat straw, biochar, zeolite, and wood vinegar were added to pig manure during composting. The composting was done in the 130 L PVC reactors with 100 L effective volume for 50 days. The activation energy of pyrolysis of samples before and after composting was calculated using Friedman's method, while the pre-exponential factor was calculated using Kissinger's equation. It was observed that composting decreased the volatile content of all the samples. The additives when added together in pig manure lead to a reduction in the activation energy of decomposition, advocating the presence of simpler compounds in the compost material in comparison with the complex feedstock. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Feedback processes in cellulose thermal decomposition: implications for fire-retarding strategies and treatments

    Science.gov (United States)

    Ball, R.; McIntosh, A. C.; Brindley, J.

    2004-06-01

    A simple dynamical system that models the competitive thermokinetics and chemistry of cellulose decomposition is examined, with reference to evidence from experimental studies indicating that char formation is a low activation energy exothermal process and volatilization is a high activation energy endothermal process. The thermohydrolysis chemistry at the core of the primary competition is described. Essentially, the competition is between two nucleophiles, a molecule of water and an -OH group on C6 of an end glucosyl cation, to form either a reducing chain fragment with the propensity to undergo the bond-forming reactions that ultimately form char, or a levoglucosan end-fragment that depolymerizes to volatile products. The results of this analysis suggest that promotion of char formation under thermal stress can actually increase the production of flammable volatiles. Thus, we would like to convey an important safety message in this paper: in some situations where heat and mass transfer is restricted in cellulosic materials, such as furnishings, insulation, and stockpiles, the use of char-promoting treatments for fire retardation may have the effect of increasing the risk of flaming combustion.

  16. Case study for model validation : assessing a model for thermal decomposition of polyurethane foam.

    Energy Technology Data Exchange (ETDEWEB)

    Dowding, Kevin J.; Leslie, Ian H. (New Mexico State University, Las Cruces, NM); Hobbs, Michael L.; Rutherford, Brian Milne; Hills, Richard Guy (New Mexico State University, Las Cruces, NM); Pilch, Martin M.

    2004-10-01

    A case study is reported to document the details of a validation process to assess the accuracy of a mathematical model to represent experiments involving thermal decomposition of polyurethane foam. The focus of the report is to work through a validation process. The process addresses the following activities. The intended application of mathematical model is discussed to better understand the pertinent parameter space. The parameter space of the validation experiments is mapped to the application parameter space. The mathematical models, computer code to solve the models and its (code) verification are presented. Experimental data from two activities are used to validate mathematical models. The first experiment assesses the chemistry model alone and the second experiment assesses the model of coupled chemistry, conduction, and enclosure radiation. The model results of both experimental activities are summarized and uncertainty of the model to represent each experimental activity is estimated. The comparison between the experiment data and model results is quantified with various metrics. After addressing these activities, an assessment of the process for the case study is given. Weaknesses in the process are discussed and lessons learned are summarized.

  17. Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed

    Science.gov (United States)

    2013-01-01

    Background The process of thermal decomposition of dichloromethane (DCM) and chlorobenzene (MCB) during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%. PMID:23289764

  18. Thermoanalytical studies of carbamazepine: hydration/dehydration, thermal decomposition, and solid phase transitions

    Directory of Open Access Journals (Sweden)

    Mônia Aparecida Lemos Pinto

    2014-12-01

    Full Text Available Carbamazepine (CBZ, a widely used anticonvulsant drug, can crystallize and exhibits four polymorphic forms and one dihydrate. Anhydrous CBZ can spontaneously absorb water and convert to the hydrate form whose different crystallinity leads to lower biological activity. The present study was concerned to the possibility of recovering the hydrated form by heating. The thermal behavior of spontaneously hydrated carbamazepine was investigated by TG/DTG-DTA and DSC in dynamic atmospheres of air and nitrogen, which revealed that the spontaneous hydration of this pharmaceutical resulted in a Form III hydrate with 1.5 water molecules. After dehydration, this anhydrous Form III converted to Form I, which melted and decomposed in a single event, releasing isocyanic acid, as shown by evolved gas analysis using TG-FTIR. Differential scanning calorimetry analyses revealed that Form III melted and crystallized as Form I, and that subsequent cooling cycles only generated Form I by crystallization. Solid state decomposition kinetic studies showed that there was no change in the substance after the elimination of water by heating to 120 °C. Activation energies of 98 ± 2 and 93 ± 2 kJ mol-1 were found for the hydrated and dried samples, respectively, and similar profiles of activation energy as a function of conversion factor were observed for these samples.

  19. Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed

    Directory of Open Access Journals (Sweden)

    Olek Malgorzata

    2013-01-01

    Full Text Available Abstract Background The process of thermal decomposition of dichloromethane (DCM and chlorobenzene (MCB during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%.

  20. Analysis of the Compounds from the BTEX Group, Emitted During Thermal Decomposition of Alkyd Resin

    Directory of Open Access Journals (Sweden)

    Kubecki M.

    2012-09-01

    Full Text Available Suitability of the given binding agent for the moulding sands preparation depends on the one hand on the estimation of technological properties of the sand and the mould made of it and the obtained casting quality and on the other hand on the assessment of this sand influence on the natural and working environment. Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. If in the initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin (phenol-formaldehyde, urea, furfuryl, urea-furfuryl, alkyd under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene, and also polycyclic aromatic hydrocarbons (PAH can be formed and released.

  1. Numerical study of hydrogen peroxide thermal decomposition in a shock tube

    Science.gov (United States)

    Bhatti, Muhammad Rizwan; Sheikh, Nadeem Ahmed; Manzoor, Shehryar; Khan, Muhammad Mahabat; Ali, Muzaffar

    2017-06-01

    Hydrogen peroxide (H2O2) has its significance during the combustion of heavy hydrocarbons in the internal combustion (IC) engines. Owing to its importance the measurements of H2O2 dissociation rate have been reported mostly using the shock tube apparatus. These types of experimental measurements are although quite reliable but require high cost. On the other hand, numerical simulations provide low cost and reliable solutions especially using computation fluid dynamics (CFD) software. In the current study an experimental shock tube flow is modeled using open access platform OpenFOAM to investigate the thermal decomposition of H2O2. Using two different convective schemes, limitedLinear and upwind, the propagation of shock wave and resultant dissociation reaction are simulated. The results of the simulations are compared with the experimental data. It is observed that the rate constant measured using the simulation data deviates from the experimental results in the low temperature range and approaches the experimental values as the temperature is raised.

  2. Pyrolysis kinetics and thermal decomposition behavior of polycarbonate - a TGA-FTIR study

    Directory of Open Access Journals (Sweden)

    Apaydin-Varol Esin

    2014-01-01

    Full Text Available This study covers the thermal degradation of polycarbonate by means of Thermogravimetric Analyzer coupled with Fourier transform infrared spectrometer (TGA-FTIR. Thermogravimetric analysis of polycarbonate was carried out at four different heating rates of 5, 10, 15, and 20°C per minute from 25°C to 1000°C under nitrogen atmosphere. The results indicated that polycarbonate was decomposed in the temperature range of 425-600°C. The kinetic parameters, such as activation energy, pre-exponential factor and reaction order were determined using five different kinetic models; namely Coast-Redfern, Friedman, Kissinger, Flynn-Wall-Ozawa (FWO, and Kissinger-Akahira-Sunose (KAS. Overall decomposition reaction order was determined by Coats-Redfern method as 1.5. Average activation energy was calculated as 150.42, 230.76, 216.97, and 218.56 kJ/mol by using Kissinger, Friedman, FWO, and KAS models, respectively. Furthermore, the main gases released during the pyrolysis of polycarbonate were determined as CO2, CH4, CO, H2O, and other lower molecular weight hydrocarbons such as aldehydes, ketones and carbonyls by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer.

  3. Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

    Science.gov (United States)

    Beuria, P. C.; Biswal, S. K.; Mishra, B. K.; Roy, G. G.

    2017-03-01

    The kinetics of removal of loss on ignition (LOI) by thermal decomposition of hydrated minerals present in natural iron ores (i.e., kaolinite, gibbsite, and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor (FBR) using isothermal methods of kinetic analysis. Experiments in the FBR in batch processes were carried out at different temperatures (300 to 1200°C) and residence time (1 to 30 min) for four different iron ore samples with various LOIs (2.34wt% to 9.83wt%). The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity ( U mf). We observed that, below a certain critical temperature, the FBR did not effectively reduce the LOI to a desired level even with increased residence time. The results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100°C. The kinetics for low-LOI samples (controlled physical moisture removal), followed by a higher activation energy (chemically controlled removal of LOI). In the case of high-LOI samples, three different kinetics mechanisms prevail at different temperature regimes. At temperature up to 450°C, diffusion kinetics prevails (removal of physical moisture); at temperature from 450 to 650°C, chemical kinetics dominates during removal of matrix moisture. At temperatures greater than 650°C, nucleation and growth begins to influence the rate of removal of LOI.

  4. Monitoring the formation of carbide crystal phases during the thermal decomposition of 3d transition metal dicarboxylate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Huba, ZJ; Carpenter, EE

    2014-06-06

    Single molecule precursors can help to simplify the synthesis of complex alloys by minimizing the amount of necessary starting reagents. However, single molecule precursors are time consuming to prepare with very few being commercially available. In this study, a simple precipitation method is used to prepare Fe, Co, and Ni fumarate and succinate complexes. These complexes were then thermally decomposed in an inert atmosphere to test their efficiency as single molecule precursors for the formation of metal carbide phases. Elevated temperature X-ray diffraction was used to identify the crystal phases produced upon decomposition of the metal dicarboxylate complexes. Thermogravimetric analysis coupled with an infrared detector was used to identify the developed gaseous decomposition products. All complexes tested showed a reduction from the starting M2+ oxidation state to the M oxidation state, upon decomposition. Also, each complex tested showed CO2 and H2O as gaseous decomposition products. Nickel succinate, iron succinate, and iron fumarate complexes were found to form carbide phases upon decomposition. This proves that transition metal dicarboxylate salts can be employed as efficient single molecule precursors for the formation of metal carbide crystal phases.

  5. Shock tube study on the thermal decomposition of fluoroethane using infrared laser absorption detection of hydrogen fluoride.

    Science.gov (United States)

    Matsugi, Akira; Shiina, Hiroumi

    2014-08-28

    Motivated by recent shock tube studies on the thermal unimolecular decomposition of fluoroethanes, in which unusual trends have been reported for collisional energy-transfer parameters, the rate constants for the thermal decomposition of fluoroethane were investigated using a shock tube/laser absorption spectroscopy technique. The rate constants were measured behind reflected shock waves by monitoring the formation of HF by IR absorption at the R(1) transition in the fundamental vibrational band near 2476 nm using a distributed-feedback diode laser. The peak absorption cross sections of this absorption line have also been determined and parametrized using the Rautian-Sobel'man line shape function. The rate constant measurements covered a wide temperature range of 1018-1710 K at pressures from 100 to 290 kPa, and the derived rate constants were successfully reproduced by the master equation calculation with an average downward energy transfer, ⟨ΔEdown⟩, of 400 cm(-1).

  6. Thermal Decomposition of Potential Ester Biofuels. Part I: Methyl Acetate and Methyl Butanoate

    Energy Technology Data Exchange (ETDEWEB)

    Porterfield, Jessica P.; Bross, David H.; Ruscic, Branko; Thorpe, James H.; Nguyen, Thanh Lam; Baraban, Joshua H.; Stanton, John F.; Daily, John W.; Ellison, G. Barney

    2017-06-09

    Two methyl esters have been examined as models for the pyrolysis of biofuels. Dilute samples (0.06 - 0.13%) of methyl acetate (CH3COOCH3) and methyl butanoate (CH3CH2CH2COOCH3) were entrained in (He, Ar) carrier gas and decomposed in a set of flash-pyrolysis micro-reactors. The pyrolysis products resulting from the methyl esters were detected and identified by vacuum ultraviolet photoionization mass spectrometry. Complementary product identification was provided by matrix infrared absorption spectroscopy. Pyrolysis pressures in the pulsed micro-reactor were roughly 20 Torr and residence times through the reactors were approximately 25 - 150 µs. Reactor temperatures of 300 – 1600 K were explored. Decomposition of CH3COOCH3 commences at 1000 K and the initial products are (CH2=C=O and CH3OH). As the micro-reactor is heated to 1300 K, a mixture of (CH2=C=O and CH3OH, CH3, CH2=O, H, CO, CO2) appears. The thermal cracking of CH3CH2CH2COOCH3 begins at 800 K with the formation of (CH3CH2CH=C=O, CH3OH). By 1300 K, the pyrolysis of methyl butanoate yields a complex mixture of (CH3CH2CH=C=O, CH3OH, CH3, CH2=O, CO, CO2, CH3CH=CH2, CH2CHCH2, CH2=C=CH2, HCCCH2, CH2=C=C=O, CH2=CH2, HCΞCH, CH2=C=O). Based on the results from the thermal cracking of methyl acetate and methyl butanoate, we predict several important decomposition channels for the pyrolysis of fatty acid methyl esters, R CH2-COOCH3. The lowest energy fragmentation will be a 4-center elimination of methanol to form the ketene, RCH=C=O. At higher temperatures, concerted

  7. Thermal Decomposition of Potential Ester Biofuels. Part I: Methyl Acetate and Methyl Butanoate.

    Science.gov (United States)

    Porterfield, Jessica P; Bross, David H; Ruscic, Branko; Thorpe, James H; Nguyen, Thanh Lam; Baraban, Joshua H; Stanton, John F; Daily, John W; Ellison, G Barney

    2017-06-22

    Two methyl esters were examined as models for the pyrolysis of biofuels. Dilute samples (0.06-0.13%) of methyl acetate (CH3COOCH3) and methyl butanoate (CH3CH2CH2COOCH3) were entrained in (He, Ar) carrier gas and decomposed in a set of flash-pyrolysis microreactors. The pyrolysis products resulting from the methyl esters were detected and identified by vacuum ultraviolet photoionization mass spectrometry. Complementary product identification was provided by matrix infrared absorption spectroscopy. Pyrolysis pressures in the pulsed microreactor were about 20 Torr and residence times through the reactors were roughly 25-150 μs. Reactor temperatures of 300-1600 K were explored. Decomposition of CH3COOCH3 commences at 1000 K, and the initial products are (CH2═C═O and CH3OH). As the microreactor is heated to 1300 K, a mixture of CH2═C═O and CH3OH, CH3, CH2═O, H, CO, and CO2 appears. The thermal cracking of CH3CH2CH2COOCH3 begins at 800 K with the formation of CH3CH2CH═C═O and CH3OH. By 1300 K, the pyrolysis of methyl butanoate yields a complex mixture of CH3CH2CH═C═O, CH3OH, CH3, CH2═O, CO, CO2, CH3CH═CH2, CH2CHCH2, CH2═C═CH2, HCCCH2, CH2═C═C═O, CH2═CH2, HC≡CH, and CH2═C═O. On the basis of the results from the thermal cracking of methyl acetate and methyl butanoate, we predict several important decomposition channels for the pyrolysis of fatty acid methyl esters, R-CH2-COOCH3. The lowest-energy fragmentation will be a 4-center elimination of methanol to form the ketene RCH═C═O. At higher temperatures, concerted fragmentation to radicals will ensue to produce a mixture of species: (RCH2 + CO2 + CH3) and (RCH2 + CO + CH2═O + H). Thermal cracking of the β C-C bond of the methyl ester will generate the radicals (R and H) as well as CH2═C═O + CH2═O. The thermochemistry of methyl acetate and its fragmentation products were obtained via the Active Thermochemical Tables (ATcT) approach, resulting in ΔfH298(CH3COOCH3) = -98

  8. Direct Growth of CuO Nanorods on Graphitic Carbon Nitride with Synergistic Effect on Thermal Decomposition of Ammonium Perchlorate

    Directory of Open Access Journals (Sweden)

    Linghua Tan

    2017-05-01

    Full Text Available Novel graphitic carbon nitride/CuO (g-C3N4/CuO nanocomposite was synthesized through a facile precipitation method. Due to the strong ion-dipole interaction between copper ions and nitrogen atoms of g-C3N4, CuO nanorods (length 200–300 nm, diameter 5–10 nm were directly grown on g-C3N4, forming a g-C3N4/CuO nanocomposite, which was confirmed via X-ray diffraction (XRD, transmission electron microscopy (TEM, field emission scanning electron microscopy (FESEM, and X-ray photoelectron spectroscopy (XPS. Finally, thermal decomposition of ammonium perchlorate (AP in the absence and presence of the prepared g-C3N4/CuO nanocomposite was examined by differential thermal analysis (DTA, and thermal gravimetric analysis (TGA. The g-C3N4/CuO nanocomposite showed promising catalytic effects for the thermal decomposition of AP. Upon addition of 2 wt % nanocomposite with the best catalytic performance (g-C3N4/20 wt % CuO, the decomposition temperature of AP was decreased by up to 105.5 °C and only one decomposition step was found instead of the two steps commonly reported in other examples, demonstrating the synergistic catalytic activity of the as-synthesized nanocomposite. This study demonstrated a successful example regarding the direct growth of metal oxide on g-C3N4 by ion-dipole interaction between metallic ions, and the lone pair electrons on nitrogen atoms, which could provide a novel strategy for the preparation of g-C3N4-based nanocomposite.

  9. The surface quasiliquid melt acceleration and the role of thermodynamic phase in the thermal decomposition of crystalline organic explosives

    Energy Technology Data Exchange (ETDEWEB)

    Henson, Bryan F [Los Alamos National Laboratory

    2010-01-01

    We show that melt acceleration in the thermal decomposition of crystalline organic solids is a manifestation of the surface quasiliquid phase. We derive a single universal rate law for melt acceleration that is a simple function of the metastable liquid activity below the melting point, and has a zero order term proportional to the quasiliquid thickness. We argue that the underlying mechanisms of this model will provide a molecular definition for the stability of the class of secondary explosives.

  10. Fabrication of ammonium perchlorate/copper-chromium oxides core-shell nanocomposites for catalytic thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Eslami, Abbas, E-mail: eslami@umz.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Juibari, Nafise Modanlou [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Hosseini, Seyed Ghorban [Department of Chemistry, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of)

    2016-09-15

    The ammonium perchlorate/Cu(II)-Cr(III)-oxides(AP/Cu-Cr-O) core-shell nanocomposites were in-situ prepared by deposition of copper and chromium oxides on suspended ammonium perchlorate particles in ethyl acetate as solvent. The results of differential scanning calorimetery (DSC) and thermal gravimetric analysis (TGA) experiments showed that the nanocomposites have excellent catalytic effect on the thermal decomposition of AP, so that the released heat increases up to about 3-fold over initial values, changing from 450 J/g for pure AP to 1510 J/g for most appropriate mixture. For better comparison, single metal oxide/AP core-shell nanocomposite have also been prepared and the results showed that they have less catalytic effect respect to mixed metal oxides system. Scanning electron microscopy (SEM) results revealed homogenous deposition of nanoparticles on the surface of AP and fabrication of core-shell structures. The kinetic parameters of thermal decomposition of both pure AP and AP/Cu-Cr-O samples have been calculated by Kissinger method and the results showed that the values of pre-exponential factor and activation energy are higher for AP/Cu-Cr-O nanocomposite. The better catalytic effect of Cu-Cr-O nanocomposites is probably attributed to the synergistic effect between Cu{sup 2+} and Cr{sup 3+} in the nanocomposites, smaller particle size and more crystal defect. - Highlights: • The Cu-Cr-O nanoparticles were synthesized by chemical liquid deposition method. • Then, the AP/Cu-Cr-O core-shell nanocomposites were prepared. • The core-shell samples showed high catalytic activity for AP decomposition. • Thermal decomposition of samples occurs at lower temperature range.

  11. Total control of chromium in tanneries - thermal decomposition of filtration cake from enzymatic hydrolysis of chrome shavings.

    Science.gov (United States)

    Kocurek, P; Kolomazník, K; Bařinová, M; Hendrych, J

    2017-04-01

    This paper deals with the problem of chromium recovery from chrome-tanned waste and thus with reducing the environmental impact of the leather industry. Chrome-tanned waste was transformed by alkaline enzymatic hydrolysis promoted by magnesium oxide into practically chromium-free, commercially applicable collagen hydrolysate and filtration cake containing a high portion of chromium. The crude and magnesium-deprived chromium cakes were subjected to a process of thermal decomposition at 650°C under oxygen-free conditions to reduce the amount of this waste and to study the effect of magnesium removal on the resulting products. Oxygen-free conditions were applied in order to prevent the oxidation of trivalent chromium into the hazardous hexavalent form. Thermal decomposition products from both crude and magnesium-deprived chrome cakes were characterized by high chromium content over 50%, which occurred as eskolaite (Cr2O3) and magnesiochromite (MgCr2O4) crystal phases, respectively. Thermal decomposition decreased the amount of chrome cake dry feed by 90%. Based on the performed experiments, a scheme for the total control of chromium in the leather industry was designed.

  12. Solid state green synthesis and catalytic activity of CuO nanorods in thermal decomposition of potassium periodate

    Science.gov (United States)

    Patel, Vinay Kumar; Bhattacharya, Shantanu

    2017-09-01

    The present study reports a facile solid state green synthesis process using the leaf extracts of Hibiscus rosa-sinensis to synthesize CuO nanorods with average diameters of 15-20 nm and lengths up to 100 nm. The as-synthesized CuO nanorods were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction. The formation mechanism of CuO nanorods has been explained by involving the individual role of amide I (amino groups) and carboxylate groups under excess hydroxyl ions released from NaOH. The catalytic activity of CuO nanorods in thermal decomposition of potassium periodate microparticles (µ-KIO4) microparticles was studied by thermo gravimetric analysis measurement. The original size (~100 µm) of commercially procured potassium periodate was reduced to microscale length scale to about one-tenth by PEG200 assisted emulsion process. The CuO nanorods prepared by solid state green route were found to catalyze the thermal decomposition of µ-KIO4 with a reduction of 18 °C in the final thermal decomposition temperature of potassium periodate.

  13. Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

    Science.gov (United States)

    Walker, R. D., Jr.

    1973-01-01

    Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

  14. Synthesis of phase-pure and monodisperse iron oxide nanoparticles by thermal decomposition.

    Science.gov (United States)

    Hufschmid, Ryan; Arami, Hamed; Ferguson, R Matthew; Gonzales, Marcela; Teeman, Eric; Brush, Lucien N; Browning, Nigel D; Krishnan, Kannan M

    2015-07-07

    Superparamagnetic iron oxide nanoparticles (SPIONs) are used for a wide range of biomedical applications requiring precise control over their physical and magnetic properties, which are dependent on their size and crystallographic phase. Here we present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting magnetic properties. We investigate critical parameters for synthesis of monodisperse SPIONs by organic thermal decomposition. Three different, commonly used, iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) are evaluated under a variety of synthetic conditions. We compare the suitability of these three kinetically controlled synthesis protocols, which have in common the use of iron oleate as a starting precursor or reaction intermediate, for producing nanoparticles with specific size and magnetic properties. Monodisperse particles were produced over a tunable range of sizes from approximately 2-30 nm. Reaction parameters such as precursor concentration, addition of surfactant, temperature, ramp rate, and time were adjusted to kinetically control size and size-distribution, phase, and magnetic properties. In particular, large quantities of excess surfactant (up to 25 : 1 molar ratio) alter reaction kinetics and result in larger particles with uniform size; however, there is often a trade-off between large particles and a narrow size distribution. Iron oxide phase, in addition to nanoparticle size and shape, is critical for establishing magnetic properties such as differential susceptibility (dm/dH) and anisotropy. As an example, we show the importance of obtaining the required size and iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled. These results provide much of the information necessary to determine which iron oxide synthesis protocol is best suited to a particular

  15. Hydrogen and Carbon Black Production from Thermal Decomposition of Sub-Quality Natural Gas

    Directory of Open Access Journals (Sweden)

    M. Javadi

    2010-03-01

    Full Text Available The objective of this paper is computational investigation of the hydrogen and carbon black production through thermal decomposition of waste gases containing CH4 and H2S, without requiring a H2S separation process. The chemical reaction model, which involves solid carbon, sulfur compounds and precursor species for the formation of carbon black, is based on an assumed Probability Density Function (PDF parameterized by the mean and variance of mixture fraction and β-PDF shape. The effects of feedstock mass flow rate and reactor temperature on hydrogen, carbon black, S2, SO2, COS and CS2 formation are investigated. The results show that the major factor influencing CH4 and H2S conversions is reactor temperature. For temperatures higher than 1100° K, the reactor CH4 conversion reaches 100%, whilst H2S conversion increases in temperatures higher than 1300° K. The results reveal that at any temperature, H2S conversion is less than that of CH4. The results also show that in the production of carbon black from sub-quality natural gas, the formation of carbon monoxide, which is occurring in parallel, play a very significant role. For lower values of feedstock flow rate, CH4 mostly burns to CO and consequently, the production of carbon black is low. The results show that the yield of hydrogen increases with increasing feedstock mass flow rate until the yield reaches a maximum value, and then drops with further increase in the feedstock mass flow rate.

  16. Studies on thermal decomposition mechanism of CL-20 by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS)

    Energy Technology Data Exchange (ETDEWEB)

    Naik, N.H.; Gore, G.M. [High Energy Materials Research Laboratory, Sutarwadi, Pune 411021 (India); Gandhe, B.R. [Directorate of Armament, DRDO Bhavan, New Delhi 110011 (India); Sikder, A.K. [High Energy Materials Research Laboratory, Sutarwadi, Pune 411021 (India)], E-mail: ak_sikder@yahoo.com

    2008-11-30

    The thermal decomposition study of CL-20 (hexanitrohexaazaisowurtzitane) using pyrolysis GC/MS was carried out mainly by electron impact (EI) mode. Chemical ionization (CI) mode was used for further confirmation of identified species. Mass spectrum of CL-20 decomposition products predominantly revealed fragments with m/z 81 and 96 corresponding to C{sub 4}H{sub 5}N{sub 2}{sup +} and C{sub 4}H{sub 4}N{sub 2}O{sup +} ions, respectively. The total ion chromatogram (TIC) of CL-20 pyrolysis shows peak within first 2 min due to the presence of low molecular weight gases. Peaks corresponding to several other products were also observed including the atmospheric gases. Cyanogen formation (C{sub 2}N{sub 2}, m/z 52) observed to be enriched at the scan number 300-500. The low molecular mass range decomposition products formed by cleavage of C-N ring structure were found in majority. Additional structural information was sought by employing chemical ionization mode. The data generated during this study was instrumented in determining decomposition pathways of CL-20.

  17. Self-healing slip pulses driven by thermal decomposition: Towards identifying dynamic weakening mechanisms in seismic observations

    Science.gov (United States)

    Platt, J. D.; Viesca, R. C.; Garagash, D.

    2012-12-01

    Seismological observations indicate that earthquake ruptures commonly propagate as self-healing slip pulses, with slip duration at any location on the fault being much shorter than the total event duration [Heaton 1990]. Theoretical work has linked these slip pulses to low values of the background driving stress on the fault [Zheng and Rice 1998]. Recent experiments [Han et al. 2007;Brantut et al. 2008] have shown that fault materials may thermally decompose during shear. These endothermic reactions release pore fluid, leading to an increase in pore pressure and a decrease in temperature [Sulem and Famin 2009]. An Arrhenius kinetic controls the reaction rate, and dynamic weakening only occurs when the temperature reaches a critical temperature triggering the reaction. This abrupt change is in sharp contrast with thermal pressurization where the pore pressure increases smoothly with slip. Previous theoretical studies of thermal decomposition have focused on simple mechanical systems with imposed slip rates [Sulem and Famin 2009], or coupling to a spring-slider model [Brantut et al. 2011]. We present the first solutions to couple thermal decomposition with dynamic rupture, extending the model in Garagash [2012] to solve for self-healing slip pulses. For a range of driving stresses there are two possible slip pulses, compared with a single solution for thermal pressurization alone. One solution corresponds to small slip and a low temperature rise that precludes the reaction; the other is a larger slip solution with weakening due to thermal pressurization at the rupture tip, and weakening due to thermal decomposition in the middle of the pulse. A dramatic drop in fault strength accompanies the onset of the reaction, leading to peak slip rates coinciding with the onset of the reaction. For thermal pressurization alone the maximum strain rate always occurs at the rupture tip, and depends sensitively on the driving stress. Thermal decomposition is identified by slower

  18. Thermal decomposition of UO{sub 3}-2H{sub 2}0

    Energy Technology Data Exchange (ETDEWEB)

    Flament, T.A.

    1998-02-26

    The first part of the report summarizes the literature data regarding the uranium trioxide water system. In the second part, the experimental aspects are presented. An experimental program has been set up to determine the steps and species involved in decomposition of uranium oxide di-hydrate. Particular attention has been paid to determine both loss of free water (moisture in the fuel) and loss of chemically bound water (decomposition of hydrates). The influence of water pressure on decomposition has been taken into account.

  19. Thermal decomposition of energetic materials. 2. Deuterium isotope effects and isotopic scrambling in condensed-phase decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.; Bulusu, S.

    1993-02-01

    The products formed in the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) have been traced to using mixtures of different isotopically labeled analogues of HMX. The isotopic analogues of HMX used in the experiments include 2H, 13C, 15NO2, 15N sub ring, and 18O. The fraction of isotopic scrambling and the extent of the deuterium kinetic isotope effect (DKIE) are reported for the different thermal decomposition products. Isotopic scrambling is not observed for the N-N bond in N2O and the C-H bonds in CH2O. Only one of the C-N bonds in N-methylformamide (NMFA) undergoes isotopic scrambling. The lack of complete isotopic scrambling of the N-NO bond in 1-nitroso-3,5,7-trinitro-1,3,5,7-tetrazocine (ONTNTA) is shown to imply that some HMX decomposition occurs in the lattice. The behavior of the DKIE in different mixtures of isotopic analogues of HMX suggests that water probably acts as a catalyst in the decomposition. The results demonstrate that decomposition of HMX in the condensed phase has several reaction branches.... DKIE, Isotope effect, Isotopic scrambling, HMX, NMFA, ONTNTA, Thermal decomposition.

  20. A simple thermal decomposition-nitridation route to nanocrystalline boron nitride (BN) from a single N and B source precursor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hong; Chen Youjian [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma Jianhua, E-mail: mjh820@ustc.edu [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Nanomaterials and Chemistry Key Laboratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Tong Hanxuan; Yang Jiang; Ni Danwei; Hu Huiming; Zheng Fangqing [Oujiang College, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2011-06-09

    Graphical abstract: Display Omitted Highlights: > Nanocrystalline BN was synthesized via a thermal decomposition-nitridation route. > B and N sources come from a single cheap safe precursor NH{sub 4}HB{sub 4}O{sub 7}.3H{sub 2}O. > The reaction could be carried out in an autoclave at 650 deg. C for 8 h. > X-ray powder diffraction patterns indicate that the product is hexagonal BN. > The product has good thermal stability and oxidation resistance below 900 deg. C. - Abstract: Nanocrystalline boron nitride (BN) was synthesized via a simple thermal decomposition-nitridation route by the reaction of hydrated ammonium tetraborate (NH{sub 4}HB{sub 4}O{sub 7}.3H{sub 2}O) and metallic magnesium powders in an autoclave at 650 deg. C. The crystal phase, morphology, grain size, and chemical composition of the as-prepared products were characterized in detail by X-ray powder diffraction (XRD), energy dispersion spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The products were also studied by FT-IR and the thermogravimetric analysis (TGA). Results revealed that the as-synthesized nanocrystalline were h-BN, and they had diameters within 100 nm. They had good thermal stability and oxidation resistance in high temperature.

  1. Modified Graphene with SnO2 Nanocomposites Using Thermal Decomposition Method and Sensing Behavior Towards NO2 Gas

    Science.gov (United States)

    Sharma, Vikram

    2017-11-01

    This is the first time the graphene sample has been functionalized with metal oxide nanoparticles by thermal decomposition process. In this paper, graphene has been synthesized from natural resources using flower petals as carbon feedstock by thermal exfoliation technique at temperatures 1300 °C and the synthesis of graphene-tin oxide (SnO2) nanocomposites has been done using chemical treatment followed by thermal decomposition method. The response versus time condition has been investigated for the fabricated sample. The electrical resistance w.r.t. temperature could be explained by the thermal generation of electron-hole pairs and carrier scattering by acoustic phonons. The structural, morphological and chemical composition studies of the nanocomposites were carried out by the Raman spectroscopy, x-ray diffraction spectroscopy, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy (HRTEM). The evidence of good-quality graphene is obtained from Raman spectroscopy studies. The SEM and HRTEM images have shown that SnO2 nanoparticles are well distributed in the multilayer electron transparent graphene films. The sensor response was found to lie between 8.25 and 9.36% at 500 ppm of nitrogen dioxide, and also resistance recovered quickly without any application of heat. We believe such chemical treatment of graphene could potentially be used to manufacture a new generation of low-power nano-NO2 sensors.

  2. Study of copper-chromium oxide catalyst . I. Thermal decomposition of copper(III) chromate, CuCrO4

    Science.gov (United States)

    Hanic, F.; Horváth, I.; Plesch, G.; Gáliková, Ľ.

    1985-09-01

    The kinetics, mechanism, and activation energy of the isothermal decomposition of CuCrO 4 was studied using an isothermal TG method and an X-ray high-temperature diffraction technique in either air or a flowing atmosphere of N 2. The enthalpy change ΔH of the decomposition reaction 2 CuCrO4→ CuO+ CuO+ CuCr2O4+ {3}/{2}O2 was determined by DSC analysis. The mechanism of the thermal decomposition of CuCrO 4 is well represented by the standard Avrami-Erofeev kinetic equation [- ln(1 - α)] {1}/{2} = kt . According to this mechanism, the reaction rate is controlled by the formation and growth of nuclei on the surface of the reactant. The activation energy EA of the process in air is EA = (248 ± 8) kJ mole -1, in flowing atmosphere of nitrogen EA = (229 ± 8) kJ mole -1. ΔH in air is 110 kJ mole -1, in flowing nitrogen 67 kJ mole -1. The lower values of ΔH and EA in the flowing atmosphere of nitrogen are due to the fast elimination of O 2 from the reaction interface. However, the decay of the crystalline portion of CuCrO 4 during its thermal decomposition, studied by the X-ray diffraction, is controlled by a different reaction mechanism (first-order kinetics). The reaction mechanism is discussed in the relation to the crystal structure of the reactants.

  3. Effects of Martian Surface Materials on the Thermal Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Dame, Rudger H.; Archer, Paul Douglas; Hogancamp, Joanna C.

    2017-10-01

    While hydrogen peroxide (H2O2) has been detected in the martian atmosphere, it has not been detected in surface materials. Since the Viking lander mission, we have sent instruments to Mars with the capability to detect H2O2. The Sample Analysis at Mars (SAM) instrument onboard the Curiosity Rover and Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander both detected water and oxygen releases from analyzed sediments but whether or not peroxide could be the source of these gases has not been investigated. We are investigating the possible presence of H2O2 in martian materials by analyzing Mars-relevant minerals that have been mixed with hydrogen peroxide using lab instruments configured as analogs to Mars mission instruments.The object of this research is to use lab instruments to find the effects of Mars analog minerals on hydrogen peroxide gas release temperatures, specifically gas releases of water and oxygen and also determine the effect of the peroxide on the minerals. Data that we get from the lab can then be compared to the data collected from Mars.The minerals hematite, siderite, San Carlos olivine, magnetite and nontronite were chosen as our Mars analog minerals. ~20 mg of analog Mars minerals with 5µl of 50% H2O2, and were either run immediately or placed in a sealed tube for 2, 4, or 9 days to look for changes over time with two reps being done at each time step to determine repeatability. Each sample was heated from -60 °C to 500 °C at 20 °C/min and the evolved gases were monitored with a mass spectrometer. Each sample was also analyzed with an X-ray diffraction instrument to look for changes in mineralogy.Preliminary results show three potential outcomes: 1) peroxide has no effect on the sample (e.g., hematite), 2) the mineral is unaffected but catalyzes peroxide decomposition (magnetite, siderite), or 3) peroxide alters the mineral (pyrrhotite, San Carlos olivine).

  4. Effects of Martian Surface Materials on the Thermal Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Archer, P. D., Jr.

    2017-01-01

    While hydrogen peroxide (H2O2) has been detected in the martian atmosphere, it has not been detected in surface materials. Since the Viking lander mission, we have sent instruments to Mars with the capability to detect H2O2. The Sample Analysis at Mars (SAM) instrument onboard the Curiosity Rover and Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander both detected water and oxygen releases from analyzed sediments but whether or not peroxide could be the source of these gases has not been investigated. We are investigating the possible presence of H2O2 in martian materials by analyzing Mars-relevant minerals that have been mixed with hydrogen peroxide using lab instruments configured as analogs to Mars mission instruments. The object of this research is to use lab instruments to find the effects of Mars analog minerals on hydrogen peroxide gas release temperatures, specifically gas releases of water and oxygen and also determine the effect of the peroxide on the minerals. Data that we get from the lab can then be compared to the data collected from Mars. The minerals hematite, siderite, San Carlos olivine, magnetite and nontronite were chosen as our Mars analog minerals. 20 mg of analog Mars minerals with 5µl of 50% H2O2, and were either run immediately or placed in a sealed tube for 2, 4, or 9 days to look for changes over time with two reps being done at each time step to determine repeatability. Each sample was heated from -60 degC to 500 degC at 20 degC/min and the evolved gases were monitored with a mass spectrometer. Each sample was also analyzed with an X-ray diffraction instrument to look for changes in mineralogy. Preliminary results show three potential outcomes: 1) peroxide has no effect on the sample (e.g., hematite), 2) the mineral is unaffected but catalyzes peroxide decomposition (magnetite, siderite), or 3) peroxide alters the mineral (pyrrhotite, San Carlos olivine).

  5. Thermal Decomposition Characteristics of Orthorhombic Ammonium Perchlorate (o-AP) and an 0-AP/HTPB-Based Propellant

    Energy Technology Data Exchange (ETDEWEB)

    BEHRENS JR.,RICHARD; MINIER,LEANNA M.G.

    1999-10-25

    A study to characterize the low-temperature reactive processes for o-AP and an AP/HTPB-based propellant (class 1.3) is being conducted in the laboratory using the techniques of simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and scanning electron microscopy (SEM). The results presented in this paper are a follow up of the previous work that showed the overall decomposition to be complex and controlled by both physical and chemical processes. The decomposition is characterized by the occurrence of one major event that consumes up to {approx}35% of the AP, depending upon particle size, and leaves behind a porous agglomerate of AP. The major gaseous products released during this event include H{sub 2}O, O{sub 2}, Cl{sub 2}, N{sub 2}O and HCl. The recent efforts provide further insight into the decomposition processes for o-AP. The temporal behaviors of the gas formation rates (GFRs) for the products indicate that the major decomposition event consists of three chemical channels. The first and third channels are affected by the pressure in the reaction cell and occur at the surface or in the gas phase above the surface of the AP particles. The second channel is not affected by pressure and accounts for the solid-phase reactions characteristic of o-AP. The third channel involves the interactions of the decomposition products with the surface of the AP. SEM images of partially decomposed o-AP provide insight to how the morphology changes as the decomposition progresses. A conceptual model has been developed, based upon the STMBMS and SEM results, that provides a basic description of the processes. The thermal decomposition characteristics of the propellant are evaluated from the identities of the products and the temporal behaviors of their GFRs. First, the volatile components in the propellant evolve from the propellant as it is heated. Second, the hot AP (and HClO{sub 4}) at the AP-binder interface oxidize the binder through reactions that

  6. Thermal Decomposition of Methyl Esters in Biodiesel Fuel: Kinetics, Mechanisms and Products

    Science.gov (United States)

    Chai, Ming

    Biodiesel continues to enjoy increasing popularity. However, recent studies on carbonyl compounds emissions from biodiesel fuel are inconclusive. Emissions of carbonyl compounds from petroleum diesel fuels were compared to emissions from pure biodiesel fuels and petroleum-biodiesel blends used in a non-road diesel generator. The concentration of total carbonyl compounds was the highest when the engine was idling. The carbonyl emissions, as well as ozone formation potential, from biodiesel fuel blends were higher than those emitted from petroleum diesel fuel. The sulfur content of diesel fuel and the source of biodiesel fuel were not found to have a significant impact on emissions of carbonyl compounds. Mechanism parameters of the thermal decomposition of biodiesel-range methyl esters were obtained from the results of thermal gravimetric analysis (TGA). The overall reaction orders are between 0.49 and 0.71 and the energies of activation are between 59.9 and 101.3 kJ/mole. Methyl esters in air have lower activation energies than those in nitrogen. Methyl linoleate has the lowest activation energy, followed by methyl oleate, and methyl stearate. The pyrolysis and oxidation of the three methyl esters were investigated using a semi-isothermal tubular flow reactor. The profiles of major products versus reaction temperature are presented. In the pyrolysis of methyl stearate, the primary reaction pathway is the decarboxylic reaction at the methyl ester functional group. Methyl oleate's products indicate more reactions on its carbon-carbon double bond. Methyl linoleate shows highest reactivity among the three methyl esters, and 87 products were detected. The oxidation of three methyl esters resulted in more products in all compound classes, and 55, 114, and 127 products were detected, respectively. The oxidation of methyl esters includes decarboxylation on ester group. The methyl ester's carbon chain could be oxidized as a hydrocarbon compound and form oxidized esters and

  7. Preparation and thermal decomposition of copper(II, zinc(II and cadmium(II chelates with 8-hydroxyquinoline

    Directory of Open Access Journals (Sweden)

    Crespi Marisa S.

    1999-01-01

    Full Text Available When the compounds are heated in an inert atmosphere it can be verified the consecutive partial sublimation, fusion, partial volatilization and partial thermal decomposition of the anhydrous complexes. When in an oxidating atmosphere the above process is only verified to Cu(II chelates. Anhydrous copper(II complexes present a monoclinic structure in the b form and the volatilized compound in a a form. Zinc(II and cadmium(II hydrated complexes are isomorphous and they present different cell dimensions from those reported previously.

  8. Thermal behavior and decomposition of cerium(III) butanoate, pentanoate and hexanoate salts upon heating in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Yue, Zhao

    2017-01-01

    The thermal behavior and decomposition of Ce-butanoate monohydrate (Ce(C3H7CO2)3·H2O), Ce-pentanoate (Ce(C4H9CO2)3) and Ce-hexanoate (Ce(C5H11CO2)3) were studied in a flow of argon while heating at 5 °C/min. By means of several techniques such as simultaneous TG-DTA, FTIR evolved gas analysis, in...

  9. Thermal decomposition of solder flux activators under simulated wave soldering conditions

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-01-01

    Purpose:The aim of this work is to investigate the decomposition behaviour of the activator species commonly used in the wave solder no-clean flux systems and to estimate the residue amount left after subjecting the samples to simulated wave soldering conditions. Design/methodology/approach: Chan......Purpose:The aim of this work is to investigate the decomposition behaviour of the activator species commonly used in the wave solder no-clean flux systems and to estimate the residue amount left after subjecting the samples to simulated wave soldering conditions. Design......-malic). The decomposition patterns of solder flux activators depend on their chemical nature, time of heat exposure and substrate materials. Evaporation of the residue from the surface of different materials (laminate with solder mask, copper surface or glass surface) was found to be more pronounced for succinic...

  10. Non-Thermal Plasma Combined with Cordierite-Supported Mn and Fe Based Catalysts for the Decomposition of Diethylether

    Directory of Open Access Journals (Sweden)

    Quang Hung Trinh

    2015-04-01

    Full Text Available The removal of dilute diethylether (DEE, concentration: 150 ppm from an air stream (flow rate: 1.0 L min−1 using non-thermal plasma combined with different cordierite-supported catalysts, including Mn, Fe, and mixed Mn-Fe oxides, was investigated. The experimental results showed that the decomposition of DEE occurred in a one-stage reactor without the positive synergy of plasma and supported catalysts, by which ca. 96% of DEE was removed at a specific input energy (SIE of ca. 600 J L−1, except when the mixed Mn-Fe/cordierite was used. Among the catalysts that were examined, Mn-Fe/cordierite, the catalyst that was the most efficient at decomposing ozone was found to negatively affect the decomposition of DEE in the one-stage reactor. However, when it was utilized as a catalyst in the post-plasma stage of a two-part hybrid reactor, in which Mn/cordierite was directly exposed to the plasma, the reactor performance in terms of DEE decomposition efficiency was improved by more than 10% at low values of SIE compared to the efficiency that was achieved without Mn-Fe/cordierite. The ozone that was formed during the plasma stage and its subsequent catalytic dissociation during the post-plasma stage to produce atomic oxygen therefore played important roles in the removal of DEE.

  11. ESR studies on the thermal decomposition of trimethylamine oxide to formaldehyde and dimethylamine in jumbo squid (Dosidicus gigas) extract.

    Science.gov (United States)

    Zhu, Junli; Jia, Jia; Li, Xuepeng; Dong, Liangliang; Li, Jianrong

    2013-12-15

    The effects of ferrous iron, heating temperature and different additives on the decomposition of trimethylamine oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA) and generation of free radicals in jumbo squid (Dosidicus gigas) extract during heating were evaluated by electron spin resonance (ESR). The thermal decomposition of TMAO to TMA, DMA and FA and free radical signals was observed in squid extract, whereas no DMA, FA and free radical signals were detected in cod extract or in aqueous TMAO solution in vitro at high temperatures. Significant increase in levels of DMA, FA and radicals intensity were observed in squid extract and TMAO solution in the presence of ferrous iron with increasing temperature. Hydrogen peroxide stimulated the production of DMA, FA and ESR signals in squid extract, while citric acid, trisodium citrate, calcium chloride, tea polyphenols and resveratrol had the opposite effect. Similar ESR spectra of six peaks regarded as amminium radical were detected in the squid extract and TMAO-iron(II) solution, suggesting that the amminium radical was involved in the decomposition of TMAO. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Kinetic modeling of thermal decomposition of zinc ferrite from neutral leach residues based on stochastic geometric model

    Energy Technology Data Exchange (ETDEWEB)

    Janković, Bojan, E-mail: bojanjan@ffh.bg.ac.rs [Faculty of Physical Chemistry, Department for Dynamics and Matter Structure, University of Belgrade, Studentski trg 12-16, P.O. Box 137, 11001 Belgrade (Serbia); Stopić, Srećko; Güven, Aybars; Friedrich, Bernd [IME Process Metallurgy and Metal Recycling, RWTH Aachen University, Aachen (Germany)

    2014-05-01

    The stochastic geometric model was applied to kinetic modeling the complex process of thermal decomposition of zinc ferrite from neutral leach residues, at different operating temperatures (600 °C, 750 °C, 950 °C and 1150 °C). Based on functional dependence of Avrami's constant (n) in a function of the effective activation energy (E{sub a}), it was found that at T>950 °C, the crystallization process takes place in autocatalytic stage, under the conditions where the rate of nucleation rapidly increases. It was established that the high nucleation rate can be attributed to formation of both Zn and Fe rich regions which provide a high number of heterogeneous nucleation sites. Based on the obtained final shape of the particles, it was found a strong presence of zinc, iron (present only in the form of Fe{sub 3}O{sub 4} (magnetite)), magnesium (in the form of Mg{sub 2}Si{sub 2}O{sub 6}), and also lead oxides. Thermodynamic analysis showed that the decomposition depends on the introduction of heat, and exerts a positive value of the Gibbs free energy of activation. Such a feature was expected since the ferrite system has been submitted to a forced decomposition and volatilization reactions. - Highlights: • Thermo-chemical investigations. • Autocatalytic stage of process, where the rate of nucleation rapidly increases. • Iron is present in the form of Fe{sub 3}O{sub 4} (magnetite). • The possibility of preparing of the nanosized magnetic particles. • Final product which underwent decomposition has the magnetic properties.

  13. Investigating the thermal decomposition of starch and cellulose in model systems and toasted bread using domino tandem mass spectrometry.

    Science.gov (United States)

    Golon, Agnieszka; González, Francisco Javier; Dávalos, Juan Z; Kuhnert, Nikolai

    2013-01-23

    Many dietary products containing polysaccharides, mostly starch and cellulose, are processed by thermal treatment. Similarly to the formation of caramel from mono- and disaccharides, the chemical structure of the carbohydrates is dramatically altered by heat treatment. This contribution investigates the products of thermal decomposition of pure starch and cellulose as model systems followed by an investigation of bread obtained at comparable conditions using a combination of modern mass spectrometry techniques. From both starch and cellulose, dehydrated oligomers of glucose and dehydrated glucose have been predominately observed, with oligomers of more than four glucose moieties dominating. Moreover, disproportionation and oligomers with up to six carbohydrates units are formed through unselective glycosidic bond breakage. MALDI-MS data confirm the presence of the majority of products in toasted bread.

  14. Comparison of the thermal decomposition processes of several aminoalcohol-based ZnO inks with one containing ethanolamine

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Núñez, Alberto [University of Barcelona, Department of Electronics, Martí i Franquès 1, E08028-Barcelona (Spain); Roura, Pere [University of Girona, Department of Physics, Campus Montilivi, Edif. PII, E17071-Girona, Catalonia (Spain); López, Concepción [University of Barcelona, Department of Inorganic Chemistry, Martí i Franquès 1, E08028-Barcelona (Spain); Vilà, Anna, E-mail: avila@el.ub.edu [University of Barcelona, Department of Electronics, Martí i Franquès 1, E08028-Barcelona (Spain)

    2016-09-15

    Highlights: • Four alternatives to ethanolamine as stabilizer for the chemical synthesis of ZnO with zinc acetate dihydrate are proposed: aminopropanol, aminomethyl butanol, aminophenol and aminobenzyl alcohol. • Thermal decomposition processes described. Nitrogen cyclic compounds result. • Molecule flexibility helps decomposition, and in particular aliphatic aminoalcohols (quite flexible) decompose the precursor at lower temperatures than aromatic ones (more rigid). • Aminopropanol, aminomethyl butanol and aminobenzyl crystallize ZnO at a lower temperature than ethanolamine. • Nitrogen cyclic specimens have been identified and evolve in all cases (included ethanolamine) at temperatures up to 600 °C. - Abstract: Four inks for the production of ZnO semiconducting films have been prepared with zinc acetate dihydrate as precursor salt and one among the following aminoalcohols: aminopropanol (APr), aminomethyl butanol (AMB), aminophenol (APh) and aminobenzyl alcohol (AB) as stabilizing agent. Their thermal decomposition process has been analyzed in situ by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and evolved gas analysis (EGA), whereas the solid product has been analysed ex-situ by X-ray diffraction (XRD) and infrared spectroscopy (IR). Although, except for the APh ink, crystalline ZnO is already obtained at 300 °C, the films contain an organic residue that evolves at higher temperature in the form of a large variety of nitrogen-containing cyclic compounds. The results indicate that APr can be a better stabilizing agent than ethanolamine (EA). It gives larger ZnO crystal sizes with similar carbon content. However, a common drawback of all the amino stabilizers (EA included) is that nitrogen atoms have not been completely removed from the ZnO film at the highest temperature of our experiments (600 °C).

  15. Nickel Oxide (NiO nanoparticles prepared by solid-state thermal decomposition of Nickel (II schiff base precursor

    Directory of Open Access Journals (Sweden)

    Aliakbar Dehno Khalaji

    2015-06-01

    Full Text Available In this paper, plate-like NiO nanoparticles were prepared by one-pot solid-state thermal decomposition of nickel (II Schiff base complex as new precursor. First, the nickel (II Schiff base precursor was prepared by solid-state grinding using nickel (II nitrate hexahydrate, Ni(NO32∙6H2O, and the Schiff base ligand N,N′-bis-(salicylidene benzene-1,4-diamine for 30 min without using any solvent, catalyst, template or surfactant. It was characterized by Fourier Transform Infrared spectroscopy (FT-IR and elemental analysis (CHN. The resultant solid was subsequently annealed in the electrical furnace at 450 °C for 3 h in air atmosphere. Nanoparticles of NiO were produced and characterized by X-ray powder diffraction (XRD at 2θ degree 0-140°, FT-IR spectroscopy, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD and FT-IR results showed that the product is pure and has good crystallinity with cubic structure because no characteristic peaks of impurity were observed, while the SEM and TEM results showed that the obtained product is tiny, aggregated with plate-like shape, narrow size distribution with an average size between 10-40 nm. Results show that the solid state thermal decomposition method is simple, environmentally friendly, safe and suitable for preparation of NiO nanoparticles. This method can also be used to synthesize nanoparticles of other metal oxides.

  16. Thermal decomposition of energetic materials. 2. Deuterium isotope effects and isotopic scrambling in condensed-phase decomposition of octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine. (Reannouncement with new availability information)

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.; Bulusu, S.

    1991-12-31

    The products formed in the thermal decomposition of octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX) have been traced by using mixtures of different isotopically labeled analogues of HMX. The fraction of isotropic scrambling and the extent of the deuterium kinetic isotope effect (DKIE) are reported for the different thermal decomposition products. Isotropic scrambling is not observed for the N-Nbond in N2O and the C-H bonds in CH2O. Only one of the C-N bonds in N-methylformamide (NMFA) undergoes isotropic scrambling. The lack of complete isotopic scrambling of the N-NO bond in 1-nitroso-3,5-7-trinitro- 1,3,5,7-tetrazocine (ONTNTA) is shown to imply that some HMX decomposition occurs in the lattice. The behavior of the DKIE in different mixtures of isotopic analogues of HMX suggests that water probably acts as a catalyst in the decomposition. The results demonstrate that decomposition of HMX in the condensed phase has several reaction branches.

  17. Adomian Decomposition Method for a Nonlinear Heat Equation with Temperature Dependent Thermal Properties

    Directory of Open Access Journals (Sweden)

    Ashfaque H. Bokhari

    2009-01-01

    Full Text Available The solutions of nonlinear heat equation with temperature dependent diffusivity are investigated using the modified Adomian decomposition method. Analysis of the method and examples are given to show that the Adomian series solution gives an excellent approximation to the exact solution. This accuracy can be increased by increasing the number of terms in the series expansion. The Adomian solutions are presented in some situations of interest.

  18. Ab initio investigation of the thermal decomposition of n-butylcyclohexane.

    Science.gov (United States)

    Ali, Mohamad Akbar; Dillstrom, V Tyler; Lai, Jason Y W; Violi, Angela

    2014-02-13

    Environmental and energy security concerns have motivated an increased focus on developing clean, efficient combustors, which increasingly relies on insight into the combustion chemistry of fuels. In particular, naphthenes (cycloalkanes and alkylcycloalkanes) are important chemical components of distillate fuels, such as diesel and jet fuels. As such, there is a growing interest in describing napthene reactivity with kinetic mechanisms. Use of these mechanisms in predictive combustion models aids in the development of combustors. This study focuses on the pyrolysis of n-butylcyclohexane (n-BCH), an important representative of naphthenes in jet fuels. Seven different unimolecular decomposition pathways of C-C bond fission were explored utilizing ab initio/DFT methods. Accurate reaction energies were computed using the high-level quantum composite G3B3 method. Variational transition state theory, Rice-Ramsperger-Kassel-Marcus/master equation simulations provided temperature- and pressure-dependent rate constants. Implementation of these pathways into an existing chemical kinetic mechanism improved the prediction of experimental OH radical and H2O speciation in shock tube oxidation. Simulations of this combustion showed a change in the expected decomposition chemistry of n-BCH, predicting increased production of cyclic alkyl radicals instead of straight-chain alkenes. The most prominent reaction pathway for the decomposition of n-BCH is n-BCH = C3H7 + C7H13. The results of this study provide insight into the combustion of n-BCH and will aid in the future development of naphthene kinetic mechanisms.

  19. A vacuum ultraviolet photoionization study on the thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Góbi, Sándor; Zhao, Long; Xu, Bo; Ablikim, Utuq; Ahmed, Musahid; Kaiser, Ralf I.

    2018-01-01

    Pyrolysis products of ammonium perchlorate (NH4ClO4) at 483 K were monitored on line and in situ via single photon photoionization reflectron time-of-flight spectrometry (PI-ReTOF-MS) in the photon energy range of 9.00-17.50 eV. The photoionization efficiency curves (PIE) of the subliming product molecules were collected and allowed for detection of three class of products containing chlorine, nitrogen, and oxygen including atoms and free radicals. These results suggest a new insight into possible low-temperature decomposition pathways of NH4ClO4.

  20. Signatures in magnetites formed by (Ca,Mg,Fe)CO3 thermal decomposition: Terrestrial and extraterrestrial implications

    Science.gov (United States)

    Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Carlos; Rodriguez-Navarro, Alejandro; Perez-Gonzalez, Teresa; Bazylinski, Dennis A.; Lauer, Howard V.; Romanek, Christopher S.

    2012-06-01

    It has never been demonstrated whether magnetite synthesized through the heat-dependent decomposition of carbonate precursors retains the chemical and structural features of the carbonates. In this study, synthetic (Ca,Mg,Fe)CO3 was thermally decomposed by heating from 25 to 700 °C under 1 atm CO2, and by in situ exposure under vacuum to the electron beam of a transmission electron microscope. In both cases, the decomposition of the carbonate was topotactic and resulted in porous pseudomorphs composed of oriented aggregates of magnetite nanocrystals. Both calcium and magnesium were incorporated into nanophase magnetite, forming (Ca,Mg)-magnetites and (Ca,Mg)-ferrites when these elements were present in the parent material, thus preserving the chemical signature of the precursor. These results show that magnetites synthesized in this way acquire a chemical and structural inheritance from their carbonate precursor that indicates how they were produced. These results are not only important in the determination of the origin of chemically-impure, oriented nanophase magnetite crystals in general, but they also provide important insights into the origin of the large, euhedral, chemically-pure, [111]-elongated magnetites found within Ca-, Mg- and Fe-rich carbonates of the Martian meteorite ALH84001. Based on our experimental results, the chemically-pure magnetites within ALH84001 cannot be genetically related to the Ca-, Mg- and Fe-rich carbonate matrix within which they are embedded, and an alternative explanation for their occurrence is warranted.

  1. Decomposition Characteristics of Toluene Vapor Using Titanium Dioxide Photocatalyst and Zeolite Thermally Sprayed on an Aluminum Fiber Filter.

    Science.gov (United States)

    Hori, Hajime; Hinoue, Mitsuo; Ishimatsu, Sumiyo; Fueta, Yukiko; Ishidao, Toru; Takabatake, Kaori; Yakiyama, Natsumi; Yamamoto, Kiyoshi

    Decomposition characteristics of toluene vapor by titanium dioxide photocatalyst and zeolite that are prepared by thermal spraying on an aluminum fiber filter (photocatalyst filter) were investigated. Toluene vapor was injected into a small chamber made of stainless steel, and an air cleaner equipped with the photocatalyst filter was operated. The vapor concentration in the chamber decreased exponentially. The decreasing rate of toluene vapor in the chamber depended on the initial toluene concentration, and the higher the initial vapor concentration was, the lower the decreasing rate was obtained. The decreasing rate was constant during each decomposition experiment, although the concentration decreased with time. To investigate the effect of zeolite on the reduction of the vapor concentration, we compared the decreasing rates of toluene vapor by photocatalyst filters with and without zeolite.The decreasing rate of toluene concentration using the filter without zeolite was larger than that with zeolite. The reason for this would be that photocatalyst decomposed toluene not only in air but also adsorbed in zeolite.

  2. An ab initio molecular dynamics study of thermal decomposition of 3,6-di(azido)-1,2,4,5-tetrazine.

    Science.gov (United States)

    Wu, Qiong; Zhu, Weihua; Xiao, Heming

    2014-10-21

    Ab initio molecular dynamics simulations were performed to study the thermal decomposition of isolated and crystal 3,6-di(azido)-1,2,4,5-tetrazine (DiAT). During unimolecular decomposition, the three different initiation mechanisms were observed to be N-N2 cleavage, ring opening, and isomerization, respectively. The preferential initial decomposition step is the homolysis of the N-N2 bond in the azido group. The release mechanisms of nitrogen gas are found to be very different in the early and later decomposition stages of crystal DiAT. In the early decomposition, DiAT decomposes very fast and drastically without forming any stable long-chains or heterocyclic clusters, and most of the nitrogen gases are released through rapid rupture of nitrogen-nitrogen and carbon-nitrogen bonds. But in the later decomposition stage, the release of nitrogen gas is inhibited due to low mobility, long distance from each other, and strong carbon-nitrogen bonds. To overcome the obstacles, the nitrogen gases are released through slow formation and disintegration of polycyclic networks. Our simulations suggest a new decomposition mechanism for the organic polyazido initial explosive at the atomistic level.

  3. Unveiling the structure and composition of titanium oxide nanotubes through ion exchange chemical reactions and thermal decomposition processes

    Directory of Open Access Journals (Sweden)

    Ferreira Odair P.

    2006-01-01

    Full Text Available In this paper we report the ion exchange reactions and the thermal decomposition of titanium oxide nanotubes, obtained by hydrothermal treatment of TiO2 and NaOH. Based on these results we propose a new composition for the as-prepared nanotubes as Na2Ti3O7.nH2O. Our results also suggest that nanotube walls have structure similar to those observed in the layer of the bulk Na2Ti3O7. Depending on how the washing process is performed on the nanotubes (water or acid solutions the Na+ content can be modified via the exchange reaction of Na+ by H+. Thus, a general chemical formula was also proposed: Na2-xHxTi3O7 .nH2O (0 < x < 2, x being dependent on the washing process.

  4. Monitoring thermally induced structural deformation and framework decomposition of ZIF-8 through in situ temperature dependent measurements.

    Science.gov (United States)

    Xu, Ben; Mei, Yingjie; Xiao, Zhenyu; Kang, Zixi; Wang, Rongming; Sun, Daofeng

    2017-10-18

    ZIF-8 is an easily synthesized porous material which is widely applied in gas storage/separation, catalysis, and nanoarchitecture fabrication. Thermally induced atomic displacements and the resultant framework deformation/collapse significantly influence the application of ZIF-8, and therefore, in situ temperature dependent FTIR spectroscopy was utilized to study the framework changes during heating in the oxidative environment. The results suggest that ZIF-8 undergoes three transition stages, which are the lattice expansion stage below 200 °C, the "reversible" structural deformation stage from 200 to 350 °C, and the decomposition/collapse stage over 350 °C. Our research indicates that the Zn-N bond breaks at a temperature of 350 °C in the oxidant environment, leading to a drastic deformation of the ZIF-8 structure.

  5. Determination of The Minimal Amount of Water for Effective Suppression of The Thermal Decomposition of Forest Combustible Materials

    Directory of Open Access Journals (Sweden)

    Zhdanova Alena О.

    2016-01-01

    Full Text Available Forest fires are big problem for whole the world community. The development of new effective methods is needed to increase the efficiency of the firefighting. We have investigated experimentally the suppression of thermal decomposition of different typical forest combustibles using water aerosol. Droplet sizes were 0.02-0.2mm; the concentration −3.8·10−5 m3 of water/m3, the flow rate −0.00035 l/s, flow velocity −2 m/s. Registration of the aerosol propagation and interaction with combustibles was done by high-speed video camera using Shadow Photography and Particle Tracking Velocimetry methods. The effective water volumes for fire suppression were determined together with corresponding suppression times. The obtained results could be used for improvement of the fire-fighting technologies.

  6. Investigation of the thermal decomposition of magnesium–sodium nitrate pyrotechnic composition (SR-524 and the effect of accelerated aging

    Directory of Open Access Journals (Sweden)

    Zaheer-ud-din Babar

    2017-03-01

    Full Text Available The aging behavior of the pyrotechnics is influenced by the storage atmosphere and more specifically on the temperature and humidity levels. The investigated composition SR 524 is a military pyrotechnic composition that is used as a tracer. The accelerated aging of the SR 524 composition has been carried out at a temperature of 70 °C and relative humidity of 70 percent. The results indicate that there is significant change in the thermal behavior, kinetic parameters and the morphology of the aged composition. The decomposition temperature and the activation energy were found to be lowered in the aged composition. The activation energy of the aged composition decreased nearly 57 percent. SEM micrographs of the aged composition revealed the development of micro cracks as a result of accelerated aging. XRD spectra of the aged composition showed the presence of magnesium hydroxide indicating the reaction between magnesium and water vapors present in the highly humid atmosphere.

  7. Economically attractive route for the preparation of high quality magnetic nanoparticles by the thermal decomposition of iron(III) acetylacetonate

    Science.gov (United States)

    Effenberger, Fernando B.; Couto, Ricardo A.; Kiyohara, Pedro K.; Machado, Giovanna; Masunaga, Sueli H.; Jardim, Renato F.; Rossi, Liane M.

    2017-03-01

    The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate economically attractive alternatives for the synthesis of iron oxide nanoparticles without compromising their size and shape control. We have found that some affordable and reasonably less priced alcohols, such as 1,2-octanediol and cyclohexanol, may replace the commonly used and expensive 1,2-hexadecanediol, providing an economically attractive route for the synthesis of high quality magnetic nanoparticles. The relative cost for the preparation of Fe3O4 NPs is reduced to only 21% and 9% of the original cost when using 1,2-octanediol and cyclohexanol, respectively.

  8. Alumina-Supported Manganese Catalysts for Soot Combustion Prepared by Thermal Decomposition of KMnO4

    Directory of Open Access Journals (Sweden)

    Agustin Bueno-López

    2012-09-01

    Full Text Available Alumina-supported manganese catalysts with cryptomelane and/or birnessite structure have been prepared using a simple method based on the thermal decomposition of potassium permanganate. The samples have been characterized by XRD, FTIR, TGA, DSC, N2 adsorption at −196 °C, SEM, H2-TPR and XPS, and their catalytic activity for soot combustion has been tested and compared to that of a reference Pt/alumina catalyst. The thermal decomposition of alumina-supported KMnO4 yields a mixture of supported birnessite and potassium manganate which is the most effective, among those prepared, to lower the soot combustion temperature. However, this material is not useful for soot combustion because the accelerating effect is not based on a catalytic process but on the oxidation of soot by potassium manganate. A suitable soot combustion catalyst is obtained after potassium manganate is removed by water washing, yielding only the birnessite phase on the γ-Al2O3 support. This birnessite phase can be transformed into cryptomelane by calcination at 600 °C. These two samples, γ-Al2O3-supported birnessite and cryptomelane are suitable catalysts for soot combustion in NOx/O2 mixtures, as their catalytic activity is based on the NO2-assited mechanism, that is, both catalysts accelerate the oxidation of NO to NO2 and NO2 promotes soot oxidation. The soot combustion temperatures obtained with these birnessite/cryptomelane alumina-supported catalysts are similar to that obtained with the reference Pt/alumina catalyst.

  9. Sol–gel method to prepare graphene/Fe{sub 2}O{sub 3} aerogel and its catalytic application for the thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Yuanfei; Li, Xiaoyu; Li, Guoping; Luo, Yunjun, E-mail: yjluo@bit.edu.cn [Beijing Institute of Technology, School of Materials Science and Engineering (China)

    2015-10-15

    Graphene/Fe{sub 2}O{sub 3} (Gr/Fe{sub 2}O{sub 3}) aerogel was synthesized by a simple sol–gel method and supercritical carbon dioxide drying technique. In this study, the morphology and structure were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption tests. The catalytic performance of the as-synthesized Gr/Fe{sub 2}O{sub 3} aerogel on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermogravimetric and differential scanning calorimeter. The experimental results showed that Fe{sub 2}O{sub 3} with particle sizes in the nanometer range was anchored on the Gr sheets and Gr/Fe{sub 2}O{sub 3} aerogel exhibits promising catalytic effects for the thermal decomposition of AP. The decomposition temperature of AP was obviously decreased and the total heat release increased as well.

  10. New insights on the thermal decomposition of lanthanide(III) and actinide(III) oxalates: from neodymium and cerium to plutonium

    OpenAIRE

    De Almeida, Lucie; Grandjean, Stéphane; Vigier, Nicolas; Patisson, Fabrice

    2012-01-01

    International audience; Lanthanides are often used as surrogates to study the properties of actinide compounds. Their behaviour is considered to be quite similar as they both possess f valence electrons and are close in size and chemical properties. This study examines the potential of using two lanthanides (neodymium and cerium) as surrogates for plutonium during the thermal decomposition of isomorphic oxalate compounds, in the trivalent oxidation state, into oxides. Thus, the thermal decomp...

  11. Thermal decomposition mechanisms of the methoxyphenols: formation of phenol, cyclopentadienone, vinylacetylene, and acetylene.

    Science.gov (United States)

    Scheer, Adam M; Mukarakate, Calvin; Robichaud, David J; Nimlos, Mark R; Ellison, G Barney

    2011-11-24

    The pyrolyses of the guaiacols or methoxyphenols (o-, m-, and p-HOC(6)H(4)OCH(3)) have been studied using a heated SiC microtubular (μ-tubular) reactor. The decomposition products are detected by both photoionization time-of-flight mass spectroscopy (PIMS) and matrix isolation infrared spectroscopy (IR). Gas exiting the heated SiC μ-tubular reactor is subject to a free expansion after a residence time of approximately 50-100 μs. The PIMS reveals that, for all three guaiacols, the initial decomposition step is loss of methyl radical: HOC(6)H(4)OCH(3) → HOC(6)H(4)O + CH(3). Decarbonylation of the HOC(6)H(4)O radical produces the hydroxycyclopentadienyl radical, C(5)H(4)OH. As the temperature of the μ-tubular reactor is raised to 1275 K, the C(5)H(4)OH radical loses a H atom to produce cyclopentadienone, C(5)H(4)═O. Loss of CO from cyclopentadienone leads to the final products, acetylene and vinylacetylene: C(5)H(4)═O → [CO + 2 HC≡CH] or [CO + HC≡C-CH═CH(2)]. The formation of C(5)H(4)═O, HCCH, and CH(2)CHCCH is confirmed with IR spectroscopy. In separate studies of the (1 + 1) resonance-enhanced multiphoton ionization (REMPI) spectra, we observe the presence of C(6)H(5)OH in the molecular beam: C(6)H(5)OH + λ(275.1 nm) → [C(6)H(5)OH Ã] + λ(275.1nm) → C(6)H(5)OH(+). From the REMPI and PIMS signals and previous work on methoxybenzene, we suggest that phenol results from a radical/radical reaction: CH(3) + C(5)H(4)OH → [CH(3)-C(5)H(4)OH]* → C(6)H(5)OH + 2H.

  12. Thermal decomposition of energetic materials 85: Cryogels of nanoscale hydrazinium diperchlorate in resorcinol-formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Tappan, Bryce C.; Brill, Thomas B. [Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States)

    2003-04-01

    The objective of this work was to try to desensitize an energetic material by using sol-gel processing and freeze drying to incorporate the energetic material into the fuel matrix on the nano (or at least submicron) particle size scale. Hydrazinium diperchlorate ([N{sub 2}H{sub 6}][ClO{sub 4}]{sub 2} or HP{sub 2}) and resorcinol-formaldehyde (RF) were chosen as the oxidizer and fuel, respectively. Solid loading up to 88% HP{sub 2} was achieved by using the sol gel-to-cryogel method. Various weight percentages of HP{sub 2} in RF were characterized by elemental analysis, scanning electron (SEM) and optical microscopy, T-jump/FTIR spectroscopy, DSC, and drop-weight impact. SEM indicated that 20-50 nm diameter HP{sub 2} plates aggregated into porous 400-800 nm size clusters. Below 80% HP{sub 2} the cryogels are less sensitive to impact than physical mixtures having the same ratios of HP{sub 2} and RF. The decomposition temperatures of the cryogels are higher than that of pure HP{sub 2}, which is consistent with their lower impact sensitivity. The heat of decomposition as measured at a low heating rate increases with increasing percentage of HP{sub 2}. The cryogels and physical mixtures release similar amounts of energy, but the cryogels exhibit mainly a single exotherm by DSC whereas the physical mixtures showed a two-step energy release. Flash pyrolysis revealed gaseous product ratios suggestive of more energy being released from the cryogels than the physical mixtures. Cryogels also burn faster by visual observation. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Thermal Decomposition Reaction of cis-6-Phenyl-5,6-(2-phenylpropilydene-3,3-tetramethylene-1,2,4-trioxacyclohexane in Different Solvents

    Directory of Open Access Journals (Sweden)

    L. F. R. Cafferata

    2000-03-01

    Full Text Available The kinetics of the thermal decomposition reaction of cis-6-phenyl-5,6-(2-phenyl-propilydene-3,3-tetramethylene-1,2,4-trioxacyclohexane (I was investigated in the temperature range of 100-130°C in selected solvents of different physicochemical properties to evaluate a solvent effect on the reaction.

  14. Characterization of volatile organic compounds from human analogue decomposition using thermal desorption coupled to comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

    Science.gov (United States)

    Stadler, Sonja; Stefanuto, Pierre-Hugues; Brokl, Michał; Forbes, Shari L; Focant, Jean-François

    2013-01-15

    Complex processes of decomposition produce a variety of chemicals as soft tissues, and their component parts are broken down. Among others, these decomposition byproducts include volatile organic compounds (VOCs) responsible for the odor of decomposition. Human remains detection (HRD) canines utilize this odor signature to locate human remains during police investigations and recovery missions in the event of a mass disaster. Currently, it is unknown what compounds or combinations of compounds are recognized by the HRD canines. Furthermore, a comprehensive decomposition VOC profile remains elusive. This is likely due to difficulties associated with the nontarget analysis of complex samples. In this study, cadaveric VOCs were collected from the decomposition headspace of pig carcasses and were further analyzed using thermal desorption coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (TD-GC × GC-TOFMS). Along with an advanced data handling methodology, this approach allowed for enhanced characterization of these complex samples. The additional peak capacity of GC × GC, the spectral deconvolution algorithms applied to unskewed mass spectral data, and the use of a robust data mining strategy generated a characteristic profile of decomposition VOCs across the various stages of soft-tissue decomposition. The profile was comprised of numerous chemical families, particularly alcohols, carboxylic acids, aromatics, and sulfides. Characteristic compounds identified in this study, e.g., 1-butanol, 1-octen-3-ol, 2-and 3-methyl butanoic acid, hexanoic acid, octanal, indole, phenol, benzaldehyde, dimethyl disulfide, and trisulfide, are potential target compounds of decomposition odor. This approach will facilitate the comparison of complex odor profiles and produce a comprehensive VOC profile for decomposition.

  15. TRANSITION AND DECOMPOSITION TEMPERATURES OF CEMENT PHASES - A COLLECTION OF THERMAL ANALYSIS DATA

    Directory of Open Access Journals (Sweden)

    Nick C. Collier

    2016-10-01

    Full Text Available Thermal analysis techniques provide the cement chemist with valuable tools to qualify and quantify the products formed during the hydration of cementitious materials. These techniques are commonly used alongside complimentary techniques such as X-ray diffraction and electron microscopy/energy dispersive spectroscopy to confirm the composition of phases present and identify amorphous material unidentified by other techniques. The most common thermal analysis techniques used by cement chemists are thermogravimetry, differential thermal analysis and differential scanning calorimetry. In order to provide a useful reference tool to the cement chemist, this paper provides a brief summary of the temperatures at which phase changes occur in the most common cement hydrates in the range 0-800°C in order to aid phase identification.

  16. Formation of a metallic glass by thermal decomposition of Fe(CO)5

    DEFF Research Database (Denmark)

    Wonterghem, Jacques van; Mørup, Steen; Charles, Stuart W.

    1985-01-01

    Iron pentacarbonyl has been thermally decomposed in an organic liquid. Mössbauer spectroscopy and x-ray diffraction studies show that the sample contains small particles of a metallic glass. Annealing of the particles at 523 K results in crystallization of the particles into a mixture of α-Fe and......-Fe5C2. The mechanism of glass formation is discussed....

  17. Improved accuracy and precision in δ15 NAIR measurements of explosives, urea, and inorganic nitrates by elemental analyzer/isotope ratio mass spectrometry using thermal decomposition.

    Science.gov (United States)

    Lott, Michael J; Howa, John D; Chesson, Lesley A; Ehleringer, James R

    2015-08-15

    Elemental analyzer systems generate N(2) and CO(2) for elemental composition and isotope ratio measurements. As quantitative conversion of nitrogen in some materials (i.e., nitrate salts and nitro-organic compounds) is difficult, this study tests a recently published method - thermal decomposition without the addition of O(2) - for the analysis of these materials. Elemental analyzer/isotope ratio mass spectrometry (EA/IRMS) was used to compare the traditional combustion method (CM) and the thermal decomposition method (TDM), where additional O(2) is eliminated from the reaction. The comparisons used organic and inorganic materials with oxidized and/or reduced nitrogen and included ureas, nitrate salts, ammonium sulfate, nitro esters, and nitramines. Previous TDM applications were limited to nitrate salts and ammonium sulfate. The measurement precision and accuracy were compared to determine the effectiveness of converting materials containing different fractions of oxidized nitrogen into N(2). The δ(13) C(VPDB) values were not meaningfully different when measured via CM or TDM, allowing for the analysis of multiple elements in one sample. For materials containing oxidized nitrogen, (15) N measurements made using thermal decomposition were more precise than those made using combustion. The precision was similar between the methods for materials containing reduced nitrogen. The %N values were closer to theoretical when measured by TDM than by CM. The δ(15) N(AIR) values of purchased nitrate salts and ureas were nearer to the known values when analyzed using thermal decomposition than using combustion. The thermal decomposition method addresses insufficient recovery of nitrogen during elemental analysis in a variety of organic and inorganic materials. Its implementation requires relatively few changes to the elemental analyzer. Using TDM, it is possible to directly calibrate certain organic materials to international nitrate isotope reference materials without off

  18. Development of a QSPR model for predicting thermal stabilities of nitroaromatic compounds taking into account their decomposition mechanisms.

    Science.gov (United States)

    Fayet, Guillaume; Rotureau, Patricia; Joubert, Laurent; Adamo, Carlo

    2011-10-01

    The molecular structures of 77 nitroaromatic compounds have been correlated to their thermal stabilities by combining the quantitative structure-property relationship (QSPR) method with density functional theory (DFT). More than 300 descriptors (constitutional, topological, geometrical and quantum chemical) have been calculated, and multilinear regressions have been performed to find accurate quantitative relationships with experimental heats of decomposition (-ΔH). In particular, this work demonstrates the importance of accounting for chemical mechanisms during the selection of an adequate experimental data set. A reliable QSPR model that presents a strong correlation with experimental data for both the training and the validation molecular sets (R (2) = 0.90 and 0.84, respectively) was developed for non-ortho-substituted nitroaromatic compounds. Moreover, its applicability domain was determined, and the model's predictivity reached 0.86 within this applicability domain. To our knowledge, this work has produced the first QSPR model, developed according to the OECD principles of regulatory acceptability, for predicting the thermal stabilities of energetic compounds.

  19. Influence of Chemical Treatment on Thermal Decomposition and Crystallite Size of Coir Fiber

    Science.gov (United States)

    Manjula, R.; Raju, N. V.; Chakradhar, R. P. S.; Kalkornsurapranee, Ekwipoo; Johns, Jobish

    2018-01-01

    Coir fibers were treated with sodium hydroxide (NaOH) and glutaraldehyde (GA). The influence of alkali and aldehyde treatment on thermal degradation and crystallinity of coir fiber was studied in detail. Thermogravimetric analysis and X-ray diffraction techniques were mainly used to characterize the coir samples. Activation energy of degradation was calculated from Broido and Horowitz-Metzger equations. NaOH-treated samples showed an increase in thermal stability. Removal of impurities such as waxy and fatty acid residues from the coir fiber by reacting with strong base solution improved the stability of fiber. Crosslinking of cellulose with GA in the fiber enhanced the stability of the material. Scanning electron microscopy was employed to analyze the change in surface morphology upon chemical treatment. Improvement in the properties suggests that NaOH and GA can be effectively used to modify coir fiber with excellent stability.

  20. Thermal Decomposition of 1,5-Dinitrobiuret (DNB): Direct Dynamics Trajectory Simulations and Statistical Modeling

    Science.gov (United States)

    2011-05-03

    gaseous products were identified using mass spectrometry and Fourier transform infrared spectroscopy.1,4 DSC analysis revealed that thermal...apply, because the molecular transformations are too complex. A useful approach to treating such system is quasi-classical, direct dynamics...A.; Li, G.; Lim, K.; Lu, D.; Peslherbe, G. H.; Song, K.; Swamy, K. N.; Vande Linde, S. R.; Varandas, A.; Wang, H.; Wolf, R. J. VENUS99: A general

  1. Decomposition of tar in gas from updraft gasifier by thermal cracking

    DEFF Research Database (Denmark)

    Brandt, Peder; Henriksen, Ulrik Birk

    2000-01-01

    Continuing earlier work with tar reduction by partial oxidation of pyrolysis gas [1] thermal cracking has been evaluated as a gas cleaning process. The work has been focusing on cleaning gas from updraft gasifiers, and the long term purpose is to develop a tar cleaning unit based on thermal...... cracking. An experimental set-up has been built, in which a flow of contaminated gas can be heated up to 1290°C in a reactor made of pure Al2O3. Four measurements were made. Three with gas from a pyrolysis unit simulating updraft gasifier, and one with gas from an updraft gasifier. Cracking temperatures...... was 1200, 1250 and 1290°C, and the residence time at this temperature was 0.5 second. The measurements show that at the selected residence time of 0.5 second, the gas flow in a thermal tar cracking unit has to be heated to at least 1250°C to achieve sufficient tar cleaning. At 1290°C, a tar content as low...

  2. Magnetic changes accompanying the thermal decomposition of nontronite /in air/ and its relevance to Martian mineralogy

    Science.gov (United States)

    Moskowitz, B. M.; Hargraves, R. B.

    1982-11-01

    It is found that the thermal treatment of nontronite in air, for long periods at 700 C or short periods at 900 C, results in the destruction of the nontronite structure, a distinct reddening in color, and a large increase in magnetic susceptibility and saturation magnetization. Measurements and calculations of the magnetic properties suggest that the magnetism is due to the presence of ultrafine particles of alpha or gamma Fe2O3. The highly magnetic thermally treated nontronite is amorphous to X-rays consistent with an ultrafine grain size. Prolonged heating results in the growth of alpha Fe2O3, while reflectivity spectra of a sample heated for 1 hr at 900 C indicate the presence of an opaque, magnetite-like phase in addition to alpha Fe2O3. It is found that the thermally treated nontronite has chemical, color, and magnetic properties similar to those found by Viking on Mars. It is concluded that these results indicate an origin for the fine grained Martian surface material by repeated impacts into an Fe-rich smectite-charged regolith (Weldon et al., 1980).

  3. Thermal Decomposition of Methyl Acetate (CH_3COOCH_3) in a Flash-Pyrolysis Micro-Reactor

    Science.gov (United States)

    Porterfield, Jessica P.; Bross, David H.; Ruscic, Branko; Thorpe, James H.; Nguyen, Thanh Lam; Baraban, Joshua H.; Stanton, John F.; Daily, John W.; Ellison, Barney

    2017-06-01

    The thermal decomposition of methyl acetate (CH_3COOCH_3) has been studied in a set of flash pyrolysis micro-reactors. Samples were diluted to (0.06 - 0.13%) in carrier gases (He, Ar) and subjected to temperatures of 300 - 1600 K at roughly 20 Torr. After residence times of approximately 25 - 150 μseconds, the unimolecular pyrolysis products were detected by vacuum ultraviolet photoionization mass spectrometry at 10.487 eV (118.2 nm). Complementary product identification was provided by matrix isolation infrared spectroscopy. Decomposition began at 1000 K with the observation of (CH_2=C=O, CH_3OH), products of a four centered rearrangement with a Δ_{rxn}H_{298} = 39.1 ± 0.2 kcal mol^{-1}. As the micro-reactor was heated to 1300 K, a mixture of (CH_2=C=O, CH_3OH, CH_3, CH_2=O, H, CO, CO_2) appeared. A new novel pathway is calculated in which both methyl groups leave behind CO_2 simultaneously, Δ_{rxn}H_{298} = 74.5 ± 0.4 kcal mol^{-1}. This pathway is in contrast to step-wise loss of methyl radical, which can go in two ways: Δ_{rxn}H_{298} (CH_3COOCH_3 → CH_3 + COOCH_3) = 95.4 ± 0.4 kcal mol^{-1}, Δ_{rxn}H_{298} (CH_3COOCH_3 → CH_3COO + CH_3) = 88.0 ± 0.3 kcal mol^{-1}.

  4. Monodisperse Iron Oxide Nanoparticles by Thermal Decomposition: Elucidating Particle Formation by Second-Resolved in Situ Small-Angle X-ray Scattering

    Science.gov (United States)

    2017-01-01

    The synthesis of iron oxide nanoparticles (NPs) by thermal decomposition of iron precursors using oleic acid as surfactant has evolved to a state-of-the-art method to produce monodisperse, spherical NPs. The principles behind such monodisperse syntheses are well-known: the key is a separation between burst nucleation and growth phase, whereas the size of the population is set by the precursor-to-surfactant ratio. Here we follow the thermal decomposition of iron pentacarbonyl in the presence of oleic acid via in situ X-ray scattering. This method allows reaction kinetics and precursor states to be followed with high time resolution and statistical significance. Our investigation demonstrates that the final particle size is directly related to a phase of inorganic cluster formation that takes place between precursor decomposition and particle nucleation. The size and concentration of clusters were shown to be dependent on precursor-to-surfactant ratio and heating rate, which in turn led to differences in the onset of nucleation and concentration of nuclei after the burst nucleation phase. This first direct observation of prenucleation formation of inorganic and micellar structures in iron oxide nanoparticle synthesis by thermal decomposition likely has implications for synthesis of other NPs by similar routes. PMID:28572705

  5. Investigation of thermal decomposition as the kinetic process that causes the loss of crystalline structure in sucrose using a chemical analysis approach (part II).

    Science.gov (United States)

    Lee, Joo Won; Thomas, Leonard C; Jerrell, John; Feng, Hao; Cadwallader, Keith R; Schmidt, Shelly J

    2011-01-26

    High performance liquid chromatography (HPLC) on a calcium form cation exchange column with refractive index and photodiode array detection was used to investigate thermal decomposition as the cause of the loss of crystalline structure in sucrose. Crystalline sucrose structure was removed using a standard differential scanning calorimetry (SDSC) method (fast heating method) and a quasi-isothermal modulated differential scanning calorimetry (MDSC) method (slow heating method). In the fast heating method, initial decomposition components, glucose (0.365%) and 5-HMF (0.003%), were found in the sucrose sample coincident with the onset temperature of the first endothermic peak. In the slow heating method, glucose (0.411%) and 5-HMF (0.003%) were found in the sucrose sample coincident with the holding time (50 min) at which the reversing heat capacity began to increase. In both methods, even before the crystalline structure in sucrose was completely removed, unidentified thermal decomposition components were formed. These results prove not only that the loss of crystalline structure in sucrose is caused by thermal decomposition, but also that it is achieved via a time-temperature combination process. This knowledge is important for quality assurance purposes and for developing new sugar based food and pharmaceutical products. In addition, this research provides new insights into the caramelization process, showing that caramelization can occur under low temperature (significantly below the literature reported melting temperature), albeit longer time, conditions.

  6. INFLUENCE OF VARIOUS FACTORS ON THE THERMAL DECOMPOSITION OF ALKALINE-REDUCING SUBSTANCES

    Directory of Open Access Journals (Sweden)

    V. A. Golybin

    2014-01-01

    Full Text Available Summary. According to the modern technology of sugar production normative expansion reducing substances in the cleaning diffusion juice, should be held in the main liming controlled temperature with an excess of lime alkalinity, followed by removal of the decay products have appeared due to the adsorption of calcium carbonate in the processing of juice carbon dioxide. Test data show the growth rate of thermochemical quantities of sucrose decay with increasing temperature, with the greatest degree in the experiments with a small share of reducing substances in solutions. With increase in the proportion of reducing substances to 0,3 %, the rate is reduced to about twice, with a 80 ° C and found to decrease its rate of growth . Main liming process preceded progressive preliming , not only where the epimerization faster but less stable , and the decomposition of fructose in the composition of the reducing substances to produce reactive products influencing the alkalinity of the solution and the surface state of microparticles of calcium hydroxide . The presence on the surface OH-groups and the appearance of tumors in the working environment, having in their structures group (= CO, (= O, (- СОН contributes to the appearance of induced hydrogen bonds and partial reduction of the specific surface of the mass transfer between the solid particles and the components of the solution. Carboxyl group reduce the level of active alkalinity, which as a result of blocking is limited, which reduces the pH of the environment and the decay constant reducing substances. When heated to about 85 °C decomposed 20% of the reducing substances, and chromaticity increased by 83,1 %, taking into account the heating and hot main liming chromaticity increased by 116,9 %. That is, the more reducing substances remain in solution after the first stage of the main liming, the stronger chroma increases upon subsequent heating and hot workability.

  7. A computational domain decomposition approach for solving coupled flow-structure-thermal interaction problems

    Directory of Open Access Journals (Sweden)

    Eugenio Aulisa

    2009-04-01

    Full Text Available Solving complex coupled processes involving fluid-structure-thermal interactions is a challenging problem in computational sciences and engineering. Currently there exist numerous public-domain and commercial codes available in the area of Computational Fluid Dynamics (CFD, Computational Structural Dynamics (CSD and Computational Thermodynamics (CTD. Different groups specializing in modelling individual process such as CSD, CFD, CTD often come together to solve a complex coupled application. Direct numerical simulation of the non-linear equations for even the most simplified fluid-structure-thermal interaction (FSTI model depends on the convergence of iterative solvers which in turn rely heavily on the properties of the coupled system. The purpose of this paper is to introduce a flexible multilevel algorithm with finite elements that can be used to study a coupled FSTI. The method relies on decomposing the complex global domain, into several local sub-domains, solving smaller problems over these sub-domains and then gluing back the local solution in an efficient and accurate fashion to yield the global solution. Our numerical results suggest that the proposed solution methodology is robust and reliable.

  8. Thermal expansion and decomposition of jarosite: a high-temperature neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory; Hickmott, Donald D [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2009-01-01

    The structure of deuterated jarosite, KFe{sub 3}(SO{sub 4}){sub 2}(OD){sub 6}, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate {approx}10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH){sub 6}] octahedra and [SO{sub 4}] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, a = a{sub 0} + a{sub 1} T, where a{sub 0} = 1.01 x 10{sup -4} K{sup -1} and a{sub 1} = -1.15 x 10{sup -7} K{sup -2}. On heating, the hydrogen bonds, O1{hor_ellipsis}D-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D{hor_ellipsis}O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

  9. Numerical Investigation of AdBlue Droplet Evaporation and Thermal Decomposition in the Context of NOx-SCR Using a Multi-Component Evaporation Model

    Directory of Open Access Journals (Sweden)

    Kaushal Nishad

    2018-01-01

    Full Text Available To cope with the progressive tightening of the emission regulations, gasoline and diesel engines will continuously require highly improved exhaust after-treatment systems. In the case of diesel engines, the selective catalytic reduction (SCR appears as one of the widely adopted technologies to reduce NOx (nitrogen oxides emissions. Thereby, with the help of available heat from exhaust gas, the injected urea–water solution (UWS turns inside the exhaust port immediately into gaseous ammonia (NH3 by evaporation of mixture and thermal decomposition of urea. The reaction and conversion efficiency mostly depend upon the evaporation and subsequent mixing of the NH3 into the exhaust gas, which in turn depends upon the engine loading conditions. Up to now, the aggregation of urea after evaporation of water and during the thermal decomposition of urea is not clearly understood. Hence, various scenarios for the urea depletion in the gaseous phase that can be envisaged have to be appraised under SCR operating conditions relying on an appropriate evaporation description. The objective of the present paper is therefore fourfold. First, a reliable multi-component evaporation model that includes a proper binary diffusion coefficient is developed for the first time in the Euler–Lagrangian CFD (computational fluid dynamics framework to account properly for the distinct evaporation regimes of adBlue droplets under various operating conditions. Second, this model is extended for thermal decomposition of urea in the gaseous phase, where, depending on how the heat of thermal decomposition of urea is provided, different scenarios are considered. Third, since the evaporation model at and around the droplet surface is based on a gas film approach, how the material properties are evaluated in the film influences the process results is reported, also for the first time. Finally, the impact of various ambient temperatures on the adBlue droplet depletion characteristics

  10. Research on the thermal decomposition of Mongolian Baganuur lignite and Naryn sukhait bituminous coal

    Directory of Open Access Journals (Sweden)

    A. Ariunaa

    2016-03-01

    Full Text Available The technical characteristics, elemental composition of the organic and mineral matters, ash melting behaviors and carbonization and gasification reactivities of coals from Baganuur and Naryn sukhait deposits were investigated. The results of proximate and ultimate analysis confirmed that the coal from Baganuur deposit can be graded as a low rank lignite B2 mark coal and Naryn sukhait coal is a bituminous G mark one. The carbonization and gasification experiments were performed using TGA apparatus and fixed bed quartz reactor. The data obtained with two experimental reactors showed that Baganuur lignite had lower thermal stability and much higher CO2 gasification reactivity at 950°C as compared to those for Naryn sukhait bituminous coal.Mongolian Journal of Chemistry 16 (42, 2015, 22-29

  11. Pure CuCr2O4 nanoparticles: Synthesis, characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Hosseini, Seyed Ghorban; Abazari, Reza; Gavi, Azam

    2014-11-01

    In the present paper a pure phase of the copper chromite spinel nanoparticles (CuCr2O4 SNPs) were synthesized via the sol-gel route using citric acid as a complexing agent. Then, the CuCr2O4 SNPs has been characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In the next step, with the addition of Cu-Cr-O nanoparticles (NPs), the effects of different parameters such as Cu-Cr-O particle size and the Cu/Cr molar ratios on the thermal behavior of Cu-Cr-O NPs + AP (ammonium perchlorate) mixtures were investigated. As such, the catalytic effect of the Cu-Cr-O NPs for thermal decomposition of AP was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA/DSC results showed that the samples with different morphologies exhibited different catalytic activity in different stages of thermal decomposition of AP. Also, in the presence of Cu-Cr-O nanocatalysts, all of the exothermic peaks of AP shifted to a lower temperature, indicating the thermal decomposition of AP was enhanced. Moreover, the heat released (ΔH) in the presence of Cu-Cr-O nanocatalysts was increased to 1490 J g-1.

  12. The thermal decomposition of the benzyl radical in a heated micro-reactor. II. Pyrolysis of the tropyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Buckingham, Grant T. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA; National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden Colorado 80401, USA; Porterfield, Jessica P. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA; Kostko, Oleg [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Troy, Tyler P. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Ahmed, Musahid [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Robichaud, David J. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden Colorado 80401, USA; Nimlos, Mark R. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden Colorado 80401, USA; Daily, John W. [Department of Mechanical Engineering, Center for Combustion and Environmental Research, University of Colorado, Boulder, Colorado 80309-0427, USA; Ellison, G. Barney [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA

    2016-07-05

    Cycloheptatrienyl (tropyl) radical, C7H7, was cleanly produced in the gas-phase, entrained in He or Ne carrier gas, and subjected to a set of flash-pyrolysis micro-reactors. The pyrolysis products resulting from C7H7 were detected and identified by vacuum ultraviolet photoionization mass spectrometry. Complementary product identification was provided by infrared absorption spectroscopy. Pyrolysis pressures in the micro-reactor were roughly 200 Torr and residence times were approximately 100 us. Thermal cracking of tropyl radical begins at 1100 K and the products from pyrolysis of C7H7 are only acetylene and cyclopentadienyl radicals. Tropyl radicals do not isomerize to benzyl radicals at reactor temperatures up to 1600 K. Heating samples of either cycloheptatriene or norbornadiene never produced tropyl (C7H7) radicals but rather only benzyl (C6H5CH2). The thermal decomposition of benzyl radicals has been reconsidered without participation of tropyl radicals. There are at least three distinct pathways for pyrolysis of benzyl radical: the Benson fragmentation, the methyl-phenyl radical, and the bridgehead norbornadienyl radical. These three pathways account for the majority of the products detected following pyrolysis of all of the isotopomers: C6H5CH2, C6H5CD2, C6D5CH2, and C6H5 13CH2. Analysis of the temperature dependence for the pyrolysis of the isotopic species (C6H5CD2, C6D5CH2, and C6H5 13CH2) suggests the Benson fragmentation and the norbornadienyl pathways open at reactor temperatures of 1300 K while the methyl-phenyl radical channel becomes active at slightly higher temperatures (1500 K).

  13. Doped tricalcium phosphate scaffolds by thermal decomposition of naphthalene: Mechanical properties and in vivo osteogenesis in a rabbit femur model.

    Science.gov (United States)

    Ke, Dongxu; Dernell, William; Bandyopadhyay, Amit; Bose, Susmita

    2015-11-01

    Tricalcium phosphate (TCP) is a bioceramic that is widely used in orthopedic and dental applications. TCP structures show excellent biocompatibility as well as biodegradability. In this study, porous β-TCP scaffolds were prepared by thermal decomposition of naphthalene. Scaffolds with 57.64% ± 3.54% density and a maximum pore size around 100 μm were fabricated via removing 30% naphthalene at 1150°C. The compressive strength for these scaffolds was 32.85 ± 1.41 MPa. Furthermore, by mixing 1 wt % SrO and 0.5 wt % SiO2 , pore interconnectivity improved, but the compressive strength decreased to 22.40 ± 2.70 MPa. However, after addition of polycaprolactone coating layers, the compressive strength of doped scaffolds increased to 29.57 ± 3.77 MPa. Porous scaffolds were implanted in rabbit femur defects to evaluate their biological property. The addition of dopants triggered osteoinduction by enhancing osteoid formation, osteocalcin expression, and bone regeneration, especially at the interface of the scaffold and host bone. This study showed processing flexibility to make interconnected porous scaffolds with different pore size and volume fraction porosity, while maintaining high compressive mechanical strength and excellent bioactivity. Results show that SrO/SiO2 -doped porous TCP scaffolds have excellent potential to be used in bone tissue engineering applications. © 2014 Wiley Periodicals, Inc.

  14. Photocatalytic degradation of methyl orange using ZnO nanopowders synthesized via thermal decomposition of oxalate precursor method

    Science.gov (United States)

    Kaur, Japinder; Bansal, S.; Singhal, Sonal

    2013-05-01

    ZnO nanoparticles were synthesized by thermal decomposition of oxalate precursor method. The nanopowders were characterized using powder X-ray diffraction technique and scanning electron microscopy and sample was found to have hexagonal wurtzite structure of ZnO. Average crystallite size of ZnO was found to be ∼27 nm. The photocatalytic activity of ZnO was evaluated by using methyl orange (MO) as probe molecule. It was inferred from control experiments that presence of both ZnO and UV light is necessary for photodegradation. From photocatalytic experiment it was observed that MO is completely degraded in 80 min when the amount of catalyst is 1 g/L and initial concentration of MO is 0.03 mM. The effect of dye concentration, catalyst loading and solution pH on photodegradation rate was also investigated. It was found that optimal conditions for photodegradation of MO are 1 g/L catalyst at a solution pH 9. Photodegradation of MO was found to follow pseudo-first order kinetics. Langmuir-Hinshelwood model was also used to describe the photodegradation process.

  15. Quantum mechanical studies of the kinetics, mechanisms and thermodynamics of gas-phase thermal decomposition of ethyl dithiocarbonate (xanthate

    Directory of Open Access Journals (Sweden)

    I.A. Adejoro

    2017-09-01

    Full Text Available Theoretical studies were carried out to investigate the thermal decomposition of ethyl dithiocarbonates (xanthate using Hartree–Fock at the HF/321-G* level and the density functional method with Becke 3 Lee Yang pair DFT/(B3LYP, 6-31G*, 6-31G**, 6-31+G*, MP2 and CCSD in the ab initio method of calculation using Spartan 10. Geometric parameters, such as the bond length, bond angles, dihedral angles, heat of formation, atomic charges and vibrational frequencies, were obtained. The data were used to calculate the thermodynamics parameters, change in entropy ΔS, enthalpy change ΔH, free energy G, pre-exponential factor A, rate k at 623 K, and variation of rate k with temperatures from 498–623 K at temperature intervals of 25 K. It was observed that the values obtained are in good agreement with the experimental values for the ab initio methods, and according to Arrhenius theory, the calculated rate k increases with increasing temperature.

  16. Kinetics evaluation and thermal decomposition characteristics of co-pyrolysis of municipal sewage sludge and hazelnut shell.

    Science.gov (United States)

    Zhao, Bing; Xu, Xinyang; Li, Haibo; Chen, Xi; Zeng, Fanqiang

    2018-01-01

    Hazelnut shell, as novel biomass, has lower ash content and abundant hydrocarbon, which can be utilized resourcefully with municipal sewage sludge (MSS) by co-pyrolyisis to decrease total content of pollution. The co-pyrolysis of MSS and hazelnut shell blend was analyzed by a method of multi-heating rates and different blend ratios with TG-DTG-MS under N2 atmosphere. The apparent activation energy of co-pyrolysis was calculated by three iso-conversional methods. Satava-Sestak method was used to determine mechanism function G(α) of co-pyrolysis, and Lorentzian function was used to simulate multi-peaks curves. The results showed there were four thermal decomposition stages, and the biomass were cracked and evolved at different temperature ranges. The apparent activation energy increased from 123.99 to 608.15kJ/mol. The reaction mechanism of co-pyrolysis is random nucleation and nuclei growth. The apparent activation energy and mechanism function afford a theoretical groundwork for co-pyrolysis technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Preparation of magnetic Ni-P amorphous alloy microspheres and their catalytic performance towards thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Deng, Yi; Yang, Yuanyi; Ge, Liya; Yang, Weizhong; Xie, Kenan

    2017-12-01

    In this work, a series of amorphous Ni-P alloys with diverse microspheric structures and magnetic properties were successfully prepared through a facile aqueous solution reduction using sodium hypophosphite as reducing agent with the assistance of polyvinylpyrrolidone (PVP). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and laser particle size analysis were used to investigate the structure of Ni-P alloy particles, which demonstrated that the as-prepared alloys possessed spherical morphologies and tunable compositions. We investigated the effects of the synthesis conditions including reaction temperature, initial Ni2+ concentration, pH value, and surfactant type on the morphologies and chemical constitutes of Ni-P alloy particles. Compared with other microsphere counterparts (ferromagnetism), the spherical Ni-P alloy powders with diameter of about 500 nm exhibited apparent paramagnetism. In addition, the catalytic performance of the products on the thermal decomposition of ammonium perchlorate (AP) was further investigated via thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). These Ni-P noncrystalline alloy particles with different magnetic properties and good catalytic activities would broaden the technological and industrial applications of Ni-P alloys in petrochemical reaction, soft magnetic devices, and burning rate catalysts.

  18. L1(0)-FePd nanocluster wires by template-directed thermal decomposition and subsequent hydrogen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Cui, BZ; Marinescu, M; Liu, JF

    2013-12-14

    This paper reports the nanostructure, formation mechanism, and magnetic properties of tetragonal L1(0)-type Fe55Pd45 (at. %) nanocluster wires (NCWs) fabricated by thermal decomposition of metal nitrates and subsequent hydrogen reduction in nanoporous anodized aluminum oxide templates. The as-synthesized NCWs have diameters in the range of 80-300 nm, and lengths in the range of 0.5-10 mu m. The NCWs are composed of roughly round-shaped nanoclusters in the range of 3-30 nm in size and a weighted average size of 10 nm with a mixture of single-crystal and poly-crystalline structures. The obtained intrinsic coercivity H-i(c) of 3.32 kOe at room temperature for the tetragonal Fe55Pd45 NCWs is higher than those of electrodeposited Fe-Pd solid nanowires while among the highest values reported so far for L1(0)-type FePd nanoparticles. (C) 2013 AIP Publishing LLC.

  19. Photocatalytical Properties and Theoretical Analysis of N, Cd-Codoped TiO2 Synthesized by Thermal Decomposition Method

    Directory of Open Access Journals (Sweden)

    Hongtao Gao

    2012-01-01

    Full Text Available N, Cd-codoped TiO2 have been synthesized by thermal decomposition method. The products were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, UV-visible diffuse reflectance spectra (DRS, X-ray photoelectron spectroscopy (XPS, and Brunauer-Emmett-Teller (BET specific surface area analysis, respectively. The products represented good performance in photocatalytic degradation of methyl orange. The effect of the incorporation of N and Cd on electronic structure and optical properties of TiO2 was studied by first-principle calculations on the basis of density functional theory (DFT. The impurity states, introduced by N 2p or Cd 5d, lied between the valence band and the conduction band. Due to dopants, the band gap of N, Cd-codoped TiO2 became narrow. The electronic transition from the valence band to conduction band became easy, which could account for the observed photocatalytic performance of N, Cd-codoped TiO2. The theoretical analysis might provide a probable reference for the experimentally element-doped TiO2 synthesis.

  20. Pyrolysis of aseptic packages (tetrapak) in a laboratory screw type reactor and secondary thermal/catalytic tar decomposition.

    Science.gov (United States)

    Haydary, J; Susa, D; Dudáš, J

    2013-05-01

    Pyrolysis of aseptic packages (tetrapak cartons) in a laboratory apparatus using a flow screw type reactor and a secondary catalytic reactor for tar cracking was studied. The pyrolysis experiments were realized at temperatures ranging from 650 °C to 850 °C aimed at maximizing of the amount of the gas product and reducing its tar content. Distribution of tetrapak into the product yields at different conditions was obtained. The presence of H2, CO, CH4, CO2 and light hydrocarbons, HCx, in the gas product was observed. The Aluminum foil was easily separated from the solid product. The rest part of char was characterized by proximate and elemental analysis and calorimetric measurements. The total organic carbon in the tar product was estimated by elemental analysis of tars. Two types of catalysts (dolomite and red clay marked AFRC) were used for catalytic thermal tar decomposition. Three series of experiments (without catalyst in a secondary cracking reactor, with dolomite and with AFRC) at temperatures of 650, 700, 750, 800 and 850 °C were carried out. Both types of catalysts have significantly affected the content of tars and other components in pyrolytic gases. The effect of catalyst on the tetrapack distribution into the product yield on the composition of gas and on the total organic carbon in the tar product is presented in this work. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Experimental and modeling study of the thermal decomposition of C3-C5 ethyl esters behind reflected shock waves.

    Science.gov (United States)

    Ren, Wei; Spearrin, R Mitchell; Davidson, David F; Hanson, Ronald K

    2014-03-13

    The thermal decomposition of three ethyl esters, ethyl formate (C3H6O2), ethyl acetate (C4H8O2), and ethyl propanoate (C5H10O2), was studied behind reflected shock waves using laser absorption to measure concentration time-histories of H2O, CO2, and CO. Experimental conditions covered temperatures of 1301-1636 K, pressures of 1.48-1.72 atm, and reactant concentrations of 2000 ppm in argon. Recently developed mid-infrared laser diagnostics for H2O (2.5 μm), CO2 (4.3 μm), and CO (4.6 μm) provide orders-of-magnitude greater detectivity compared to previous near-infrared absorption sensors. The experimental results have highlighted significant differences among these three ethyl esters: negligible CO2 production during ethyl formate pyrolysis, quite slow CO formation rate during ethyl acetate pyrolysis, and nearly equal formation rate of H2O, CO2, and CO during ethyl propanoate pyrolysis. Detailed kinetic modeling was performed to understand the destruction pathways of these three ethyl esters with different alkyl chain lengths. Rate of production and sensitivity analyses were also carried out to interpret the experimental results and to identify the key reactions affecting experimental results.

  2. Activity of nanosized titania synthesized from thermal decomposition of titanium (IV n-butoxide for the photocatalytic degradation of diuron

    Directory of Open Access Journals (Sweden)

    Jitlada Klongdee, Wansiri Petchkroh, Kosin Phuempoonsathaporn, Piyasan Praserthdam, Alisa S. Vangnai and Varong Pavarajarn

    2005-01-01

    Full Text Available Nanoparticles of anatase titania were synthesized by the thermal decomposition of titanium (IV n-butoxide in 1,4-butanediol. The powder obtained was characterized by various characterization techniques, such as XRD, BET, SEM and TEM, to confirm that it was a collection of single crystal anatase with particle size smaller than 15 nm. The synthesized titania was employed as catalyst for the photodegradation of diuron, a herbicide belonging to the phenylurea family, which has been considered as a biologically active pollutant in soil and water. Although diuron is chemically stable, degradation of diuron by photocatalyzed oxidation was found possible. The conversions achieved by titania prepared were in the range of 70–80% within 6 h of reaction, using standard UV lamps, while over 99% conversion was achieved under solar irradiation. The photocatalytic activity was compared with that of the Japanese Reference Catalyst (JRC-TIO-1 titania from the Catalysis Society of Japan. The synthesized titania exhibited higher rate and efficiency in diuron degradation than reference catalyst. The results from the investigations by controlling various reaction parameters, such as oxygen dissolved in the solution, diuron concentration, as well as light source, suggested that the enhanced photocatalytic activity was the result from higher crystallinity of the synthesized titania.

  3. Thermal Decomposition of Calcium Perchlorate/Iron-Mineral Mixtures: Implications of the Evolved Oxygen from the Rocknest Eolian Deposit in Gale Crater, Mars

    Science.gov (United States)

    Bruck, A. M.; Sutter, B.; Ming, D. W.; Mahaffy, P.

    2014-01-01

    A major oxygen release between 300 and 500 C was detected by the Mars Curiosity Rover Sample Analysis at Mars (SAM) instrument at the Rocknest eolian deposit. Thermal decomposition of perchlorate (ClO4-) salts in the Rocknest samples are a possible explanation for this evolved oxygen release. Releative to Na-, K-, Mg-, and Fe-perchlorate, the thermal decomposition of Ca-perchlorate in laboratory experiments released O2 in the temperature range (400-500degC) closest to the O2 release temperatures observed for the Rocknest material. Furthermore, calcium perchlorate could have been the source of Cl in the chlorinated-hydrocarbons species that were detected by SAM. Different components in the Martian soil could affect the decomposition temperature of calcium per-chlorate or another oxychlorine species. This interaction of the two components in the soil could result in O2 release temperatures consistent with those detected by SAM in the Rocknest materials. The decomposition temperatures of various alkali metal perchlorates are known to decrease in the presence of a catalyst. The objective of this work is to investigate catalytic interactions on calcium perchlorate from various iron-bearing minerals known to be present in the Rocknest material

  4. Deposition of defected graphene on (001) Si substrates by thermal decomposition of acetone

    Science.gov (United States)

    Milenov, T. I.; Avramova, I.; Valcheva, E.; Avdeev, G. V.; Rusev, S.; Kolev, S.; Balchev, I.; Petrov, I.; Pishinkov, D.; Popov, V. N.

    2017-11-01

    We present results on the deposition and characterization of defected graphene by the chemical vapor deposition (CVD) method. The source of carbon/carbon-containing radicals is thermally decomposed acetone (C2H6CO) in Ar main gas flow. The deposition takes place on (001) Si substrates at about 1150-1160 °C. We established by Raman spectroscopy the presence of single- to few- layered defected graphene deposited on two types of interlayers that possess different surface morphology and consisted of mixed sp2 and sp3 hybridized carbon. The study of interlayers by XPS, XRD, GIXRD and SEM identifies different phase composition: i) a diamond-like carbon dominated film consisting some residual SiC, SiO2 etc.; ii) a sp2- dominated film consisting small quantities of C60/C70 fullerenes and residual Si-O-, Cdbnd O etc. species. The polarized Raman studies confirm the presence of many single-layered defected graphene areas that are larger than few microns in size on the predominantly amorphous carbon interlayers.

  5. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  6. Evolution of different morphologies of CdS nanoparticles by thermal decomposition of bis(thiourea)cadmium chloride in various solvents

    Energy Technology Data Exchange (ETDEWEB)

    Gaur, Rama; Jeevanandam, P., E-mail: jeevafcy@iitr.ernet.in, E-mail: jeevafcy@iitr.ac.in [Indian Institute of Technology Roorkee, Department of Chemistry (India)

    2015-03-15

    CdS nanoparticles with different morphologies have been synthesized by thermal decomposition of bis(thiourea)cadmium chloride in different solvents without the use of any ligand/surfactant. CdS nanoparticles with pyramid, sponge-like and hexagonal disc-like morphologies were obtained in diphenyl ether (DPE), 1-octadecene (ODE) and ethylene glycol (EG), respectively. In addition, CdS nanoparticles with unique morphologies were obtained when the decomposition of the complex was carried out in mixed solvents (DPE–EG and ODE–EG). Extensive characterization of the CdS nanoparticles was carried out using powder X-ray diffraction, FT-IR spectroscopy, thermal analysis, field-emission scanning electron microscopy, diffuse reflectance spectroscopy and photoluminescence spectroscopy, and detailed mechanism of the formation of CdS nanoparticles with different morphologies in various solvents has been proposed.

  7. Evolution of different morphologies of CdS nanoparticles by thermal decomposition of bis(thiourea)cadmium chloride in various solvents

    Science.gov (United States)

    Gaur, Rama; Jeevanandam, P.

    2015-03-01

    CdS nanoparticles with different morphologies have been synthesized by thermal decomposition of bis(thiourea)cadmium chloride in different solvents without the use of any ligand/surfactant. CdS nanoparticles with pyramid, sponge-like and hexagonal disc-like morphologies were obtained in diphenyl ether (DPE), 1-octadecene (ODE) and ethylene glycol (EG), respectively. In addition, CdS nanoparticles with unique morphologies were obtained when the decomposition of the complex was carried out in mixed solvents (DPE-EG and ODE-EG). Extensive characterization of the CdS nanoparticles was carried out using powder X-ray diffraction, FT-IR spectroscopy, thermal analysis, field-emission scanning electron microscopy, diffuse reflectance spectroscopy and photoluminescence spectroscopy, and detailed mechanism of the formation of CdS nanoparticles with different morphologies in various solvents has been proposed.

  8. Facile, mild and fast thermal-decomposition reduction of graphene oxide in air and its application in high-performance lithium batteries.

    Science.gov (United States)

    Wang, Zhong-li; Xu, Dan; Huang, Yun; Wu, Zhong; Wang, Li-min; Zhang, Xin-bo

    2012-01-25

    We firstly propose a facile, mild and effective thermal-decomposition strategy to prepare high-quality graphene at a low temperature of 300 °C in only 5 min under an ambient atmosphere. Applying the advantage of this strategy that provides an oxidizing atmosphere, pure V(2)O(5)/graphene composite is successfully synthesized and exerts excellent lithium storage properties. This journal is © The Royal Society of Chemistry 2012

  9. Correlation between ionic radii of metals and thermal decomposition of supramolecular structure of azodye complexes

    Science.gov (United States)

    El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Eldesoky, A. M.; Morgan, Sh. M.

    2015-01-01

    An interesting azodye heterocyclic ligand of copper(II), cobalt(II), nickel(II) and uranyl(II) complexes have been synthesized by the reaction of metal salts with 5-(2,3-dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, magnetic moments, spectral (UV-Vis, IR, 1H and 13C NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structures of the ligand tautomers are optimized theoretically and the quantum chemical parameters are calculated. The IR spectra showed that the ligand (HL) act as monobasic tridentate/neutral bidentate through the (sbnd Ndbnd N), enolic (Csbnd O)- and/or oxygen keto moiety groups forming a five/six-membered structures. According to intramolecular hydrogen bond leads to increasing of the complexes stability. The molar conductivities show that all the complexes are non-electrolytes. The ESR spectra indicate that the free electron is in dxy orbital. The calculated bonding parameter indicates that in-plane σ-bonding is more covalent than in-plane π-bonding. The coordination geometry is five/six-coordinated trigonal bipyramidal for complex (1) and octahedral for complexes (2-6). The value of covalency factor β12 and orbital reduction factor K accounts for the covalent nature of the complexes. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The synthesized ligand (HL) and its Cu(II) complexes (1, 2 and 4) are screened for their biological activity against bacterial and fungal species. The ligand (HL) showed antimicrobial activities against Escherichia coli. The ligand (HL) and its Cu(II) complexes (2 and 4) have very high antifungal activity against Penicillium italicum. The inhibitive action of ligand (HL), against the corrosion of C-steel in 2 M HCl solution has been investigated using potentiodynamic polarization and electrochemical

  10. TG-MS analysis and kinetic study for thermal decomposition of six representative components of municipal solid waste under steam atmosphere.

    Science.gov (United States)

    Zhang, Jinzhi; Chen, Tianju; Wu, Jingli; Wu, Jinhu

    2015-09-01

    Thermal decomposition of six representative components of municipal solid waste (MSW, including lignin, printing paper, cotton, rubber, polyvinyl chloride (PVC) and cabbage) was investigated by thermogravimetric-mass spectroscopy (TG-MS) under steam atmosphere. Compared with TG and derivative thermogravimetric (DTG) curves under N2 atmosphere, thermal decomposition of MSW components under steam atmosphere was divided into pyrolysis and gasification stages. In the pyrolysis stage, the shapes of TG and DTG curves under steam atmosphere were almost the same with those under N2 atmosphere. In the gasification stage, the presence of steam led to a greater mass loss because of the steam partial oxidation of char residue. The evolution profiles of H2, CH4, CO and CO2 were well consistent with DTG curves in terms of appearance of peaks and relevant stages in the whole temperature range, and the steam partial oxidation of char residue promoted the generation of more gas products in high temperature range. The multi-Gaussian distributed activation energy model (DAEM) was proved plausible to describe thermal decomposition behaviours of MSW components under steam atmosphere. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Influence of thermal-decomposition temperatures on structures and properties of V2O5 as cathode materials for lithium ion battery

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2015-02-01

    Full Text Available Submicron spherical V2O5 particles with a uniform size and a lower crystallinity were successfully synthesized by a chemical precipitation-thermal decomposition technique using the commercial V2O5 powders as starting material. The crystal structure and grain morphology of samples were characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively. Electrochemical testing such as discharge–charge cycling (CD and cyclic voltammetry (CV were employed in evaluating their electrochemical properties as cathode materials for lithium ion battery. Results reveal that the crystallinity and crystalline size of V2O5 particles increased when the thermal-decomposition temperature increased from 400 °C to 500 °C, and their adhesiveness was also synchronously increased. This indicate that the thermal-decomposition temperature palyed a significant influence on electrochemical properties of V2O5 cathodes. The V2O5 sample obtained at 400 °C delivered not only a high initial discharge capacity of 330 mA h g−1 and also the good cycle stability during 50 cycles due to its higher values of α in crystal structure and better dispersity in grain morphology.

  12. Modeling of transport phenomena during gas hydrate decomposition by depressurization and/or thermal stimulation

    Science.gov (United States)

    Abendroth*, Sven; Klump, Jens; Thaler, Jan; Schicks, Judith M.

    2013-04-01

    In the context of the German joint project SUGAR (Submarine Gas Hydrate Reservoirs: exploration, extraction and transport) we conducted a series of experiments in the LArge Reservoir Simulator (LARS) at the German Research Centre of Geosciences Potsdam (Beeskow-Strauch et al., this volume). These experiments allow us to investigate the formation and dissociation of hydrates at large scale laboratory conditions. Processes inside LARS are modeled to study the effects of sediment properties as well as physical and chemical processes on parameters such as hydrate dissociation rate and methane production rate. The experimental results from LARS are used to provide details about processes inside the pressure vessel, validate the models through history matching, and feed back into the design of future experiments. In experiments in LARS the amount of methane produced from gas hydrates was much lower than expected. Previously published models predict a methane production rate higher than the observed in experiments and field studies (Uddin and Wright 2005; Uddin et al. 2010; Wright et al. 2011). The authors of the aforementioned studies point out that the current modeling approach overestimates the gas production rate when modeling gas production by depressurization. Uddin and Wright (2005) suggested that trapping of gas bubbles inside the porous medium is responsible for the reduced gas production rate. They point out that this behavior of multi-phase flow is not well explained by a "residual oil" model, but rather resembles a "foamy oil" model. Our study applies Uddin's (2010) "foamy oil" model and combines it with history matches of our experiments in LARS. First results indicate a better agreement between experimental and model results when using the "foamy oil" model instead of conventional models featuring gas flow in water. Further experiments with LARS, including hydrate dissociation by depressurization and thermal stimulation by in-situ combustion will be used to

  13. Thermal decomposition of ammonium perchlorate in the presence of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, WenJing [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Ping, E-mail: lipinggnipil@home.ipe.ac.cn [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Xu, HongBin; Sun, Randi; Qing, Penghui; Zhang, Yi [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-03-01

    Highlights: • The amorphous Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles containing surface hydroxyls were prepared by a hydrolytic co-precipitation method. • The Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles show excellent catalytic ability for AP decomposition. • The surface hydroxyls and amorphous form of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles promote ammonia oxidation of AP. - Abstract: An Al(OH){sub 3}·Cr(OH){sub 3} nanoparticle preparation procedure and its catalytic effect and mechanism on thermal decomposition of ammonium perchlorate (AP) were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis and mass spectroscopy (TG-MS). In the preparation procedure, TEM, SAED, and FT-IR showed that the Al(OH){sub 3}·Cr(OH){sub 3} particles were amorphous particles with dimensions in the nanometer size regime containing a large amount of surface hydroxyl under the controllable preparation conditions. When the Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles were used as additives for the thermal decomposition of AP, the TG-DSC results showed that the addition of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles to AP remarkably decreased the onset temperature of AP decomposition from approximately 450 °C to 245 °C. The FT-IR, RS and XPS results confirmed that the surface hydroxyl content of the Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles decreased from 67.94% to 63.65%, and Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles were limitedly transformed from amorphous to crystalline after used as additives for the thermal decomposition of AP. Such behavior of Al(OH){sub 3}·Cr(OH){sub 3} nanoparticles promoted the oxidation of NH{sub 3} of AP to decompose to N{sub 2}O first, as indicated by the TG-MS results, accelerating the AP thermal decomposition.

  14. Terahertz time domain spectroscopy of amorphous and crystalline aluminum oxide nanostructures synthesized by thermal decomposition of AACH

    Energy Technology Data Exchange (ETDEWEB)

    Mehboob, Shoaib, E-mail: smehboob@pieas.edu.pk [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Mehmood, Mazhar [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmed, Mushtaq [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Ahmad, Jamil; Tanvir, Muhammad Tauseef [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan); Ahmad, Izhar [National Institute of Lasers and Optronics (NILOP), Nilore 45650, Islamabad (Pakistan); Hassan, Syed Mujtaba ul [National Center for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore 45650, Islamabad (Pakistan)

    2017-04-15

    The objective of this work is to study the changes in optical and dielectric properties with the transformation of aluminum ammonium carbonate hydroxide (AACH) to α-alumina, using terahertz time domain spectroscopy (THz-TDS). The nanostructured AACH was synthesized by hydrothermal treatment of the raw chemicals at 140 °C for 12 h. This AACH was then calcined at different temperatures. The AACH was decomposed to amorphous phase at 400 °C and transformed to δ* + α-alumina at 1000 °C. Finally, the crystalline α-alumina was achieved at 1200 °C. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were employed to identify the phases formed after calcination. The morphology of samples was studied using scanning electron microscopy (SEM), which revealed that the AACH sample had rod-like morphology which was retained in the calcined samples. THz-TDS measurements showed that AACH had lowest refractive index in the frequency range of measurements. The refractive index at 0.1 THZ increased from 2.41 for AACH to 2.58 for the amorphous phase and to 2.87 for the crystalline α-alumina. The real part of complex permittivity increased with the calcination temperature. Further, the absorption coefficient was highest for AACH, which reduced with calcination temperature. The amorphous phase had higher absorption coefficient than the crystalline alumina. - Highlights: • Aluminum oxide nanostructures were obtained by thermal decomposition of AACH. • Crystalline phases of aluminum oxide have higher refractive index than that of amorphous phase. • The removal of heavier ionic species led to the lower absorption of THz radiations.

  15. Synthesis of a novel volatile platinum complex for use in CVD and a study of the mechanism of its thermal decomposition in solution

    Energy Technology Data Exchange (ETDEWEB)

    Tagge, C.D.; Simpson, R.D.; Bergman, R.G. [Univ. of California, Berkeley, CA (United States); Hostetler, M.S.; Girolami, G.S.; Nuzzo, R.G. [Univ. of Illinois, Urbana, IL (United States)

    1996-03-20

    The synthesis, characterization, chemical vapor deposition, and mechanistic investigation of the thermal decomposition in aromatic solvents of cis-bis({eta}{sup 2},{eta}{sup 1}-pent-4-en-1-yl)platinum (1) are described. Complex 1 has a unique chelated structure, giving rise to enhanced volatility, and has proved useful for the chemical vapor deposition of thin platinum films under mild conditions. Films deposited on a glass slide in a hot walled glass tube at 175{degree}C have an elemental composition of 82% Pt and 18% C. Kinetic, deuterium labeling and chemical trapping experiments indicate that the decomposition of 1 in aromatic solvents proceeds by reversible {beta}-hydride elimination followed by reversible dissociation of 1,4-pentadiene to give a 3-coordinate platinum hydride intermediate (9). Reductive elimination of 1-pentene from 9 deposits metallic platinum. The rate of decomposition exhibits a significant {beta}-deuterium isotope effect of k{sub H}/k{sub D}=3.8{+-}0.3. Added olefins are rapidly isomerized during the decomposition of 1; trapping experiments with diphenylacetylene indicate that intermediate 9 is the highly active catalyst that is responsible for the alkene isomerization. 47 refs., 5 figs.

  16. Kinetic study of the thermal decomposition of uranium metaphosphate, U(PO3)4, into uranium pyrophosphate, UP2O7

    Science.gov (United States)

    Yang, Hee-Chul; Kim, Hyung-Ju; Lee, Si-Young; Yang, In-Hwan; Chung, Dong-Yong

    2017-06-01

    The thermochemical properties of uranium compounds have attracted much interest in relation to thermochemical treatments and the safe disposal of radioactive waste bearing uranium compounds. The characteristics of the thermal decomposition of uranium metaphosphate, U(PO3)4, into uranium pyrophosphate, UP2O7, have been studied from the view point of reaction kinetics and acting mechanisms. A mixture of U(PO3)4 and UP2O7 was prepared from the pyrolysis residue of uranium-bearing spent TBP. A kinetic analysis of the reaction of U(PO3)4 into UP2O7 was conducted using an isoconversional method and a master plot method on the basis of data from a non-isothermal thermogravimetric analysis. The thermal decomposition of U(PO3)4 into UP2O7 followed a single-step reaction with an activation energy of 175.29 ± 1.58 kJ mol-1. The most probable kinetic model was determined as a type of nucleation and nuclei-growth models, the Avrami-Erofeev model (A3), which describes that there are certain restrictions on nuclei growth of UP2O7 during the solid-state decomposition of U(PO3)4.

  17. Thermal decomposition of Ln(C2H5CO2)3·H2O (Ln = Ho, Er, Tm and Yb)

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2012-01-01

    The thermal decomposition of Ho(III), Er(III), Tm(III) and Yb(III) propionate monohydrates in argon was studied by means of thermogravimetry (TG), differential thermal analysis (DTA), IR-spectroscopy and X-ray diffraction (XRD). Dehydration takes place around 90 °C. It is followed...... by the decomposition of the anhydrous propionates to Ln2O2CO3 (Ln = Ho, Er, Tm or Yb) with the evolution of CO2 and 3-pentanone (C2H5COC2H5) between 300 and 400 °C. The further decomposition of Ln2O2CO3 to the respective sesquioxides Ln2O3 is characterized by an intermediate plateau extending from approximately 500......–700 °C in the TG traces. This stage corresponds to an overall composition of Ln2O2.5(CO3)0.5 but is more probably a mixture of Ln2O2CO3 and Ln2O3. The stability of this intermediate state decreases for the lighter rare-earth (RE) compounds studied. Full conversion to Ln2O3 is achieved at about 1,100 °C...

  18. Molecular dynamics studies of the thermal decomposition of 2,3-diazabicyclo(2.2.1)hept-2-ene

    Science.gov (United States)

    Sorescu, Dan C.; Thompson, Donald L.; Raff, Lionel M.

    1995-05-01

    The reaction dynamics of the thermal gas-phase decomposition of 2,3-diazabicyclo (2.2.1)hept-2-ene-exo, exo-5,6-d2 have been investigated using classical trajectory methods on a semiempirical potential-energy surface. The global potential is written as a superposition of different reaction channel potentials containing bond stretching, bending and torsional terms, connected by parametrized switching functions. Reaction channels for stepwise and concerted cleavage of the two C-N bonds of the reactant have both been considered in construction of the potential. The geometries of 2,3-diazabicyclo(2.2.1)hept-2-ene, the diazenyl biradical and of the transition state corresponding to breaking of the remaining C-N bond of diazenyl biradical have been determined at the second order Möller-Plesset perturbation theory (MP2/6-31G*) and at Hartree-Fock (HF/6-31G*) levels, respectively. The bond dissociation energies have been estimated using the available thermochemical data and previously reported results for bicyclo(2.1.0)pentane [J. Chem. Phys. 101, 3729 (1994)]. The equilibrium geometries predicted by the semiempirical potential for reactants and products, the barrier height for thermal nitrogen extrusion from 2,3-diazabicyclo(2.2.1)hept-2-ene and the fundamental vibrational frequencies are in good to excellent agreement with the measured or ab initio calculated values. Using a projection method of the instantaneous Cartesian velocities onto the normal mode vectors and classical trajectory calculations, the dissociation dynamics of 2,3-diazabicyclo(2.2.1)hept-2-ene-exo, exo-5,6-d2 are investigated at several excitation energies in the range 60-175 kcal/mol. The results show the following: (1) The thermal reaction takes place with a preference for inversion of configuration in the reaction products, the exo-labeled bicyclo(2.1.0) pentane being the major product. The exo/endo ratio of bicyclo(2.1.0) pentane isomers is found to vary between 1.8-2.2 for the energy range

  19. Thermal decomposition of heavy rare-earth butanoates, Ln(C3H7CO2)3 (Ln = Er, Tm, Yb and Lu) in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2016-01-01

    was observed in all four compounds, but its course depends on the rare-earth element. Decomposition to sesquioxides proceeds via the formation of dioxymonocarbonates (Ln2O2CO3) and release of 4-heptanone (C3H7COC3H7) as well as carbon dioxide (CO2) without evidence for an intermediate oxobutanoate stage...... of Ln2O2CO3 and Ln2O3. The stability of this intermediate state seems to decrease with the mass of the rare-earth elements. Complete conversion to Ln2O3 is reached at about 1100 °C. The overall thermal decomposition behaviour of the title compounds is different from previous reports for other rare-earth...

  20. Bismuth sulphides prepared by thermal and hydrothermal decomposition of a single source precursor: the effect of reaction parameters on morphology, microstructure and catalytic activity.

    Science.gov (United States)

    Siqueira, Guilherme Oliveira; de Oliveira Porto, Arilza; Viana, Marcelo Machado; da Silva, Herculano Vieira; de Souza, Yara Gonçalves; da Silva, Hugo Wallison Alves; de Lima, Geraldo Magela; Matencio, Tulio

    2013-10-14

    Bismuth sulphides were prepared by thermal and hydrothermal decomposition of a precursor, bismuth tris-diethyldithiocarbamate, at different temperatures and times. The obtained results showed that the thermal decomposition of the precursor in a tube furnace was not very appropriate to control particle size and morphology. XRD results showed that at 310 °C the precursor was not fully decomposed but at 500 °C besides the orthorhombic bismuth sulphide, the metallic bismuth also started to be formed. At the highest temperature 1D crystals were formed with an apparent mean crystal size of 138 nm. However, hydrothermal decomposition was shown to be a very suitable method to control particle size and morphology just by varying some parameters such as temperature and time. For 6 hours reaction time, as temperature increased, the apparent mean crystal size decreased. The particle morphology was also very affected by this parameter, at 180 °C only 1D particles (nanorods) with lengths varying from 25 to 4700 nm were formed but at 200 °C not only 1D particles but also 2D particles were (nanosheets) obtained. Bismuth sulphide particles obtained at 180 °C and 24 hours reaction time were shown to be formed mostly by 2D particles compared to those obtained at 6 hours. It was clearly seen that the increase in reaction time and temperature led to the formation of bi-dimensional particles. The presence of 1D crystals in the samples obtained by hydrothermal decomposition at 180 °C/6 h and 180 °C/24 h is responsible for their high catalytic efficiency towards methylene blue dye degradation.

  1. Thermal decomposition of specifically phosphorylated D-glucoses and their role in the control of the Maillard reaction.

    Science.gov (United States)

    Yaylayan, Varoujan A; Machiels, David; Istasse, Louis

    2003-05-21

    One of the main shortcomings of the information available on the Maillard reaction is the lack of knowledge to control the different pathways, especially when it is desired to direct the reaction away from the formation of carcinogenic and other toxic substances to more aroma and color generation. The use of specifically phosphorylated sugars may impart some elements of control over the aroma profile generated by the Maillard reaction. Thermal decomposition of 1- and 6-phosphorylated glucoses was studied in the presence and absence of ammonia and selected amino acids through pyrolysis/gas chromatography/mass spectrometry using nonpolar PLOT and medium polar DB-1 columns. The analysis of the data has indicated that glucose-1-phosphate relative to glucose undergoes more extensive phosphate-catalyzed ring opening followed by formation of sugar-derived reactive intermediates as was indicated by a 9-fold increase in the amount of trimethylpyrazine and a 5-fold increase in the amount of 2,3-dimethylpyrazine, when pyrolyzed in the presence of glycine. In addition, glucose-1-phosphate alone generated a 6-fold excess of acetol as compared to glucose. On the other hand, glucose-6-phosphate enhanced retro-aldol reactions initiated from a C-6 hydroxyl group and increased the subsequent formation of furfural and 4-cyclopentene-1,3-dione. Furthermore, it also stabilized 1- and 3-deoxyglucosone intermediates and enhanced the formation of six carbon atom-containing Maillard products derived directly from them through elimination reactions such as 1,6-dimethyl-2,4-dihydroxy-3-(2H)-furanone (acetylformoin), 2-acetylpyrrole, 5-methylfurfural, 5-hydroxymethylfurfural, and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone (Furaneol), due to the enhanced leaving group ability of the phosphate moiety at the C-6 carbon. However, Maillard products generated through the nucleophilic action of the C-6 hydroxyl group such as 2-acetylfuran and 2,3-dihydro-3,5-dihydroxy-4H-pyran-4-one were retarded, due

  2. Synthesis of SiO{sub x}@CdS core–shell nanoparticles by simple thermal decomposition approach and studies on their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Kandula, Syam; Jeevanandam, P., E-mail: jeevafcy@iitr.ac.in

    2014-12-05

    Highlights: • SiO{sub x}@CdS nanoparticles have been synthesized by a novel thermal decomposition approach. • The method is easy and there is no need for surface functionalization of silica core. • SiO{sub x}@CdS nanoparticles show different optical properties compared to pure CdS. - Abstract: SiO{sub x}@CdS core–shell nanoparticles have been synthesized by a simple thermal decomposition approach. The synthesis involves two steps. In the first step, SiO{sub x} spheres were synthesized using StÖber’s process. Then, cadmium sulfide nanoparticles were deposited on the SiO{sub x} spheres by the thermal decomposition of cadmium acetate and thiourea in ethylene glycol at 180 °C. Electron microscopy results show uniform deposition of cadmium sulfide nanoparticles on the surface of SiO{sub x} spheres. Electron diffraction patterns confirm crystalline nature of the cadmium sulfide nanoparticles on silica and high resolution transmission electron microscopy images clearly show the lattice fringes due to cubic cadmium sulfide. Diffuse reflectance spectroscopy results show blue shift of band gap absorption of SiO{sub x}@CdS core–shell nanoparticles with respect to bulk cadmium sulfide and this is attributed to quantum size effect. Photoluminescence results show enhancement in intensity of band edge emission and weaker emission due to surface defects in SiO{sub x}@CdS core–shell nanoparticles compared to pure cadmium sulfide nanoparticles.

  3. Visible light induced degradation of methyl orange using β-Ag0.333V2O5 nanorod catalysts by facile thermal decomposition method

    Directory of Open Access Journals (Sweden)

    R. Saravanan

    2015-09-01

    Full Text Available One dimensional nanorods of β-Ag0.333V2O5 have been synthesized by facile thermal decomposition method without using any additives. The prepared sample was characterized by different physical and chemical techniques such as XRD, FE-SEM, TEM, DRS and XPS. The photocatalytic activity of β-Ag0.333V2O5 catalyst was investigated by studying the degradation of methyl orange (MO in aqueous medium under visible light exposure. The result shows β-Ag0.333V2O5 exhibits outstanding photocatalytic activity under visible light illumination.

  4. Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy, Tb, Gd, Eu and Sm)

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2014-01-01

    The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes p...

  5. Facile fabrication of Fe{sub 3}O{sub 4} and Co{sub 3}O{sub 4} microspheres and their influence on the thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yifu, E-mail: yfzhang@dlut.edu.cn; Meng, Changgong

    2016-07-25

    Fe{sub 3}O{sub 4} and Co{sub 3}O{sub 4} microspheres were successfully synthesized by the hydrothermal decomposition of iron oxalate and cobalt oxalate solution. The composition and morphology of synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The catalytic properties of the as-obtained Fe{sub 3}O{sub 4} and Co{sub 3}O{sub 4} microspheres on the thermal decomposition of ammonium perchlorate (AP) were evaluated by thermo-gravimetric analysis and differential thermal analysis (TGA/DTA) methods. The thermal decomposition temperatures of AP in the presence of 1, 2, 4 and 8 wt% of Fe{sub 3}O{sub 4} microspheres were respectively decreased by 58, 80, 102 and 129 °C (lowered to 398, 376, 354 and 327 °C). And the thermal decomposition temperatures of AP in the presence of 1, 2, 4 and 8 wt% of Co{sub 3}O{sub 4} microspheres were respectively decreased by 55, 74, 112 and 131 °C (lowered to 401, 382, 344 and 325 °C). The analysis of the thermal gravimetric analyzer couplet with infrared spectroscopy (TG-IR) test reveal that the additives can accelerate the thermal decomposition of AP via the high-temperature decomposition. All the results suggest the as-prepared Fe{sub 3}O{sub 4} and Co{sub 3}O{sub 4} microspheres have highly catalytic properties on the thermal decomposition of AP, which can be used as the promising additives in the future. - Graphical abstract: Real-time FTIR spectra to reveal the thermal decomposition process of AP. - Highlights: • Highly uniform Fe{sub 3}O{sub 4} and Co{sub 3}O{sub 4} microspheres were successfully synthesized. • The T{sub c} of AP with 1, 2, 4 and 8 wt% of Fe{sub 3}O{sub 4} microspheres was decreased by 58, 80, 102 and 129 °C. • The T{sub c} of AP with 1, 2, 4 and 8 wt% of Co{sub 3}O{sub 4} microspheres was decreased by 55, 74, 112 and 131 °C. • The thermal decomposition process of AP was detected by TG-IR.

  6. Thermal decomposition and reconstruction of CaFe-layered double hydroxide studied by X-ray diffractometry and 57Fe Mössbauer spectroscopy

    Science.gov (United States)

    Bugris, Valéria; Ádok-Sipiczki, Mónika; Anitics, Tamás; Kuzmann, Ernő; Homonnay, Zoltán; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

    2015-06-01

    In spite of numerous investigations on the various processes of the thermal decomposition and rehydration of layered double hydroxides (LDHs) by a variety sophisticated experimental means, many details are still unexplored and some contradictions are still unresolved. In this work, our efforts were focussed on clarifying the composition, structure and properties of thermally decomposed metaphases originating from CaFe-LDH, heat treated in the 373-973 K temperature range. The structure reconstruction ability of mixed metal oxide phases obtained after heat treatments was also investigated, mainly concentrating on the changes in the microenvironment of Fe(III), in the presence of controlled amount of water vapour (i.e., at different relative humidities). All samples were characterised by X-ray diffractometry, and the iron-containing phases were studied by 57Fe Mössbauer spectroscopy.

  7. In situ polyphenyl derivatisation and the effect of thermal decomposition of adsorbed and chemisorbed polyphenyls on the structure of multi-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Gergely, Andras, E-mail: doohan11@chemres.hu [Department of Surface Modification and Nanostructures, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Ujszaszy, Kalman [Mass Spectrometry Department, Institute of Structural Chemistry, Pusztaszeri ut 59-67, Chemical Research Center of the Hungarian Academy of Sciences, Budapest 1025 (Hungary); Peltz, Csaba [EGIS Pharmaceuticals PLC, Kereszturi ut 30-38, Budapest 1106 (Hungary); Kiraly, Peter; Tarkanyi, Gabor [NMR Spectroscopy Department, Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Mihaly, Judith [Department of Biological Nanochemistry, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Kalman, Erika [Department of Surface Modification and Nanostructures, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary)

    2011-05-01

    This study presents the exploitation of an alternative reaction route of deamination of arylamines to perform in situ derivatisation of multi-walled carbon nanotubes (MWCNTs) with polyphenyl (PPh) species of various masses. As a result of consecutive derivatisation, high conversion of PPh grafting of the MWCNTs was realised with the collateral outgrowth of physical modification with adsorbed additional PPhs. Applied derivatisation process exceeds the monolayer coverage related superficial saturation limitations in the overall grafting yield of the nanotubes. Thus, a linear relationship was recognized between the overall quantities of chemisorbed PPhs composed of D{sub 5}-phenylene oligomers and the applied excess of diazonium activated reagents, corresponding to {sup 2}H MAS NMR spectroscopy results. According to mass spectrometry (MS) investigations, uniform thermal decomposition of the chemisorbed PPhs modified MWCNTs was found besides the more intense and altered decomposition characteristic-featured adsorbate-chemisorbate PPhs contained MWCNTs during sequential pyrolysis under inert atmosphere. This is attributed to the pyrolysis provoked isomerisation, decomposition and the formation of adsorbed and chemisorbed PPh moieties. As a result, a mediated and an even more pronounced degradation in the order of graphitic lattice of the MWCNTs were evidenced in the adsorbate-chemisorbate and the chemisorbate PPhs contained samples by FT-Raman spectroscopy and transmission electron microscopy (TEM), respectively. {sup 2}H MAS NMR supplied results of relevant amount of deuterium in the chemisorbate PPh contained sample without traces of aromatic related MS detected volatile products, these allow us to conclude about a thermally stable derivatisation that is interpreted as an endohedral modification of the nanotubes.

  8. MOF-derived hollow NiO-ZnO composite micropolyhedra and their application in catalytic thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Yang, Ji-Min

    2017-07-01

    Ni(II)-doped Zn-based coordination polymer particles (Ni(II)-doped Zn-CPPs) with controllable shape and size were successfully synthesized by solvothermal method, which further transformed to porous ZnO-NiO composite micropolyhedra without significant alterations in shape by calcination in air. Those products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), infrared spectroscopy (IR) and gas adsorption measurements. The catalytic activity of ZnO-NiO composites for the thermal decomposition of ammonium perchlorate (AP) was investigated. The result shows that all ZnO-NiO composites efficiently catalyzed the thermal decomposition of AP, and NiO-ZnO composite hollow octahedrons have the highest catalytic efficiency compared with that of most materials reported to now, indicating that porous ZnO-NiO composite micropolyhedra could be a promising candidate material for application in AP-based propellant.

  9. Thermodynamic studies of studtite thermal decomposition pathways via amorphous intermediates UO{sub 3}, U{sub 2}O{sub 7}, and UO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaofeng [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wu, Di [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); The Gene and Lina Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99163 (United States); Xu, Hongwu [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States)

    2016-09-15

    The thermal decomposition of studtite (UO{sub 2})O{sub 2}(H{sub 2}O){sub 2}·2H{sub 2}O results in a series of intermediate X-ray amorphous materials with general composition UO{sub 3+x} (x = 0, 0.5, 1). As an extension of a structural study on U{sub 2}O{sub 7}, this work provides detailed calorimetric data on these amorphous oxygen-rich materials since their energetics and thermal stability are unknown. These were characterized in situ by thermogravimetry, and mass spectrometry. Ex situ X-ray diffraction and infrared spectroscopy characterized their chemical bonding and local structures. This detailed characterization formed the basis for obtaining formation enthalpies by high temperature oxide melt solution calorimetry. The thermodynamic data demonstrate the metastability of the amorphous UO{sub 3+x} materials, and explain their irreversible and spontaneous reactions to generate oxygen and form metaschoepite. Thus, formation of studtite in the nuclear fuel cycle, followed by heat treatment, can produce metastable amorphous UO{sub 3+x} materials that pose the risk of significant O{sub 2} gas. Quantitative knowledge of the energy landscape of amorphous UO{sub 3+x} was provided for stability analysis and assessment of conditions for decomposition.

  10. Kinetics of thermal decomposition of some biomasses in an inert environment. An investigation of the effect of lead loaded by biosorption.

    Science.gov (United States)

    Martín-Lara, María Ángeles; Iáñez-Rodríguez, Irene; Blázquez, Gabriel; Quesada, Lucía; Pérez, Antonio; Calero, Mónica

    2017-12-01

    The thermal behavior of some types of raw and lead-polluted biomasses typical in south Spain was studied by non-isothermal thermogravimetry. Experiments were carried out in nitrogen atmosphere at three heating rates (5, 10 and 20°C/min). The results of thermogravimetric tests carried out proved that the presence of lead did not change the main degradation pathways of selected biomass (almond shell (AS) and olive pomace (OP)). However, from a point of view of mass loss, lead-polluted samples showed higher decomposition temperatures and decomposition at higher rate. The determination of activation energies was performed by isoconversional methods of Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR). In general, lead-polluted samples showed lower activation energies than raw ones. Then, Coast-Redfern method was applied to determine kinetic function. The kinetic function that seems to determine the mechanism of thermal degradation of main components of all samples was nth order reaction. Finally, a model based on three parallel reactions (for three pseudocomponents) that fit to nth order reactions was evaluated. This model was appropriate to predict the pyrolysis behavior of the raw and lead-polluted samples in all pyrolysis conditions studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. On formation mechanism of Pd-Ir bimetallic nanoparticles through thermal decomposition of [Pd(NH{sub 3}){sub 4}][IrCl{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Asanova, Tatyana I., E-mail: nti@niic.nsc.ru; Asanov, Igor P. [Nikolaev Institute of Inorganic Chemistry SB RAS (Russian Federation); Kim, Min-Gyu [Pohang University of Science and Technology, Beamline Research Division (Korea, Republic of); Gerasimov, Evgeny Yu. [Boreskov Institute of Catalysis SB RAS (Russian Federation); Zadesenets, Andrey V.; Plyusnin, Pavel E.; Korenev, Sergey V. [Nikolaev Institute of Inorganic Chemistry SB RAS (Russian Federation)

    2013-10-15

    The formation mechanism of Pd-Ir nanoparticles during thermal decomposition of double complex salt [Pd(NH{sub 3}){sub 4}][IrCl{sub 6}] has been studied by in situ X-ray absorption (XAFS) and photoelectron (XPS) spectroscopies. The changes in the structure of the Pd and Ir closest to the surroundings and chemical states of Pd, Ir, Cl, and N atoms were traced in the range from room temperature to 420 Degree-Sign C in inert atmosphere. It was established that the thermal decomposition process is carried out in 5 steps. The Pd-Ir nanoparticles are formed in pyramidal/rounded Pd-rich (10-200 nm) and dendrite Ir-rich (10-50 nm) solid solutions. A d charge depletion at Ir site and a gain at Pd, as well as the intra-atomic charge redistribution between the outer d and s and p electrons of both Ir and Pd in Pd-Ir nanoparticles, were found to occur.Graphical Abstract.

  12. [Real-time analysis of polyvinyl chloride thermal decomposition/combustion products with single photon ionization/photoelectron ionization online mass spectrometer].

    Science.gov (United States)

    Chen, Wen-Dong; Hou, Ke-Yong; Chen, Ping; Li, Fang-Long; Zhao, Wu-Duo; Cui, Hua-Peng; Hua, Lei; Xie, Yuan-Yuan; Li, Hai-Yang

    2013-01-01

    With the features of a broad range of ionizable compounds, reduced fragments and simple mass spectrum, a homemade magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for time-of-flight mass spectrometer was built and applied to analyze thermal decomposition/combustion products of polyvinyl chloride (PVC). The combined ion source can be switched very fast between SPI mode and SPI-MEPEI mode for detecting different targeted compounds, and only adjusting the voltage of the electrode in the ionization region to trigger the switch. Among the PVC thermal decomposition/combustion products, HCl and CO2, which ionization energies (12.74 eV, 13.77 eV respectively) were higher than the energy of photon (10.60 eV), were ionized by MEPEI, while alkenes, dichloroethylene, benzene and its homologs, monochlorobenzene, styrene, indane, naphthalene and its homologs were ionized by SPI and MEPEI simultaneously. Spectra of interested products as a function of temperatures indicated that products are formed via two main mechanisms: (1) dechlorination and intramolecular cyclization can lead to the formation of HCl, benzene and naphthalene at 250-370 degrees C; (2) intermolecular crosslinking leads to the formation of alkyl aromatics such as toluene and xylene/ethylbenzene at 380-510 degrees C. The experimental results show that the combined ion source of SPI/ SPI-MEPEI for TOF-MS has broad application prospects in the online analysis field.

  13. Estudo cinético da decomposição térmica do pentaeretritol-tetranitrado (PETN Kinetic study of the thermal decomposition of pentaerythritol-tetranitrate (PETN

    Directory of Open Access Journals (Sweden)

    Gilson da Silva

    2008-01-01

    Full Text Available The pentaerythritol-tetranitrate (PETN is a nitroether used in explosives and propellant formulations. Due to its suitable properties, PETN is used in booster manufacture. Knowing the thermal decomposition behavior of an energetic material is very important for storage and manipulation, and the purpose of this work is to study the kinetic parameters of the decomposition of PETN, compare the results with literature data and to study the decomposition activation energy differences between two crystalline forms of PETN (tetragonal and needle by means of differential scanning calorimetry (DSC. Fourier transform infrared spectroscopy (FT-IR is used to study the two crystalline forms.

  14. Influence of aging time of oleate precursor on the magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Adriana P.; Polo-Corrales, Liliana [Department of Chemical Engineering, University of Puerto Rico, Mayagueez, Puerto Rico, PR 00681-9000 (United States); Chavez, Ermides; Cabarcas-Bolivar, Jari [Department of Physics, University of Puerto Rico, Mayagueez, Puerto Rico, PR 00681-9000 (United States); Uwakweh, Oswald N.C. [Department of General Engineering, University of Puerto Rico, Mayagueez, Puerto Rico, PR 00681-9000 (United States); Rinaldi, Carlos, E-mail: crinaldi@uprm.edu [Department of Chemical Engineering, University of Puerto Rico, Mayagueez, Puerto Rico, PR 00681-9000 (United States)

    2013-02-15

    Cobalt ferrite nanoparticles are of interest because of their room temperature coercivity and high magnetic anisotropy constant, which make them attractive in applications such as sensors based on the Brownian relaxation mechanism and probes to determine the mechanical properties of complex fluids at the nanoscale. These nanoparticles can be synthesized with a narrow size distribution by the thermal decomposition of an iron-cobalt oleate precursor in a high boiling point solvent. We studied the influence of aging time of the iron-cobalt oleate precursor on the structure, chemical composition, size, and magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method. The structure and thermal behavior of the iron-cobalt oleate was studied during the aging process. Infrared spectra indicated a shift in the coordination state of the oleate and iron/cobalt ions from bidentate to bridging coordination. Aging seemed to influence the thermal decomposition of the iron-cobalt oleate as determined from thermogravimmetric analysis and differential scanning calorimetry, where shifts in the temperatures corresponding to decomposition events and a narrowing of the endotherms associated with these events were observed. Aging promoted formation of the spinel crystal structure, as determined from X-ray diffraction, and influenced the nanoparticle magnetic properties, resulting in an increase in blocking temperature and magnetocrystalline anisotropy. Mossbauer spectra also indicated changes in the magnetic properties resulting from aging of the precursor oleate. Although all samples exhibited some degree of Brownian relaxation, as determined from complex susceptibility measurements in a liquid medium, aging of the iron-cobalt oleate precursor resulted in crossing of the in-phase {chi} Prime and out-of-phase {chi} Double-Prime components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for

  15. Thermal decomposition of a molecular material {N(n-C4H94[FeIIFeIII(C2O43]}∞ leading to ferrite: A reaction kinetics study

    Directory of Open Access Journals (Sweden)

    Bhattacharjee Ashis

    2013-01-01

    Full Text Available A multi-step thermal decomposition of a molecular precursor, {N(n-C4H94[FeIIFeIII(C2O43}∞ has been studied using non-isothermal thermogravimetry (TG measurements in the temperature range 300 to ~800 K at multiple heating rates (5, 10 and 20 K min-1. The thermal decomposition of the oxalate-based complex proceeds stepwise through a series of intermediate reactions. Two different isoconversional methods, namely, improved iterative method and model-free method are employed to evaluate the kinetic parameters: activation energy and rate of reaction, and the most probable reaction mechanism of thermal decomposition is also determined. The different reaction pathways leading to different steps in the TG profile have also been explored which are supplemented by earlier experimental observations of the present authors.

  16. Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4 Hydrogen Storage Composite.

    Science.gov (United States)

    Pei, Ziwei; Bai, Ying; Wang, Yue; Wu, Feng; Wu, Chuan

    2017-09-20

    The lightweight compound material NaNH2-NaBH4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH2-NaBH4 (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H2, NH3, B2H6, and N2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B6H12 also exists. The TG/DTA analyses show that the composite NaNH2-NaBH4 (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na3(NH2)2BH4 hydride decomposes into Na3BN2 and H2 (200-350 °C); (2) remaining Na3(NH2)2BH4 reacts with NaBH4 and Na3BN2, generating Na, BN, NH3, N2, and H2 (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.

  17. High temperature shock tube studies on the thermal decomposition of O3 and the reaction of dimethyl carbonate with O-atoms.

    Science.gov (United States)

    Peukert, S L; Sivaramakrishnan, R; Michael, J V

    2013-05-09

    The shock tube technique was used to study the thermal decomposition of ozone, O3, with a view to using this as a thermal precursor of O-atoms at high temperatures. The formation of O-atoms was measured behind reflected shock waves by using atomic resonance absorption spectrometry (ARAS). The experiments span a T-range, 819 K ≤ T ≤ 1166 K, at pressures 0.13 bar ≤ P ≤ 0.6 bar. Unimolecular rate theory provides an excellent representation of the falloff characteristics from the present and literature data on ozone decomposition at high temperatures. The present decomposition study on ozone permits its usage as a thermal source for O-atoms allowing measurements for, O + CH3OC(O)OCH3 → OH + CH3OC(O)OCH2 [A]. Reflected shock tube experiments monitoring the formation and decay of O-atoms were performed on reaction A using mixtures of O3 and CH3OC(O)OCH3, (DMC), in Kr bath gas over the T-range, 862 K ≤ T ≤ 1167 K, and pressure range, 0.15 bar ≤ P ≤ 0.33 bar. A detailed model was used to fit the O-atom temporal profile to obtain experimental rate constants for reaction A. Rate constants from the present experiments for O + DMC can be represented by the Arrhenius expression: kA(T) = 2.70 × 10(-11) exp(-2725 K/T) cm(3) molecule(-1) s(-1) (862-1167 K). Transition state theory calculations employing CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties for reaction A are in good agreement with the experimental rate constants. The theoretical rate constants can be well represented (to within ±10%) over the 500-2000 K temperature range by: kA(T) = 1.87 × 10(-20)T(2.924) exp(-2338 K/T) cm(3) molecule(-1) s(-1). The present study represents the first experimental measurement and theoretical study on this bimolecular reaction which is of relevance to the high temperature oxidation of DMC.

  18. Semi-empirical method for calculating the activation energies of the unimolecular thermal decomposition of vinyl ethers

    Science.gov (United States)

    Sargsyan, G. N.; Shakhrokh, B.; Harutyunyan, A. B.

    2015-02-01

    A semi-empirical method is proposed for calculating the activation energy of the unimolecular decomposition of complex compounds using the example of vinyl (ethyl, propyl, and butyl) ethers. The method is based on the concept of the formation of intramolecular hydrogen bonds and the possibility of calculating the energy of deformation of ether molecules upon activation, resulting in the potential surface of the transition state undergoing distortion and the transfer of a hydrogen atom from an alkyl group to a vinyl group. The energy of deformation is calculated using the Mathcad 2001i and MM2 computer programs.

  19. Studies on the thermal decomposition of lanthanum(III) valerate and lanthanum(III) caproate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Suarez Guevara, Maria Josefina

    2015-01-01

    The decomposition of La-valerate (La(C4H9CO2)3·xH2O (x ≈ 0.45)) and La-caproate (La(C5H11CO2)3·xH2O (x ≈ 0.30)) was studied upon heating at 5 C/min in a flow of argon. Using a variety of techniques including simultaneous TG-DTA, FTIR, X-ray diffraction with both laboratory Cu Kα and synchrotron...

  20. Thermal stability of the 'cave' mineral brushite CaHPO{sub 4}.2H{sub 2}O - Mechanism of formation and decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Frost, Ray L., E-mail: r.frost@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George St., GPO Box 2434, Brisbane, Queensland 4001 (Australia); Palmer, Sara J. [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George St., GPO Box 2434, Brisbane, Queensland 4001 (Australia)

    2011-07-10

    Highlights: {yields} In this study the thermal stability of brushite is reported. {yields} Such a study is relevant to the elimination of renal canal stones. {yields} A mechanism for the formation of brushite is proposed. {yields} A mechanism for the decomposition of brushite is discussed. {yields} This research has implications for the control and removal of kidney stones. - Abstract: Thermogravimetry combined with evolved gas mass spectrometry has been used to ascertain the stability of the 'cave' mineral brushite. X-ray diffraction shows that brushite from the Jenolan Caves is very pure. Thermogravimetric analysis coupled with ion current mass spectrometry shows a mass loss at 111 {sup o}C due to loss of water of hydration. A further decomposition step occurs at 190 {sup o}C with the conversion of hydrogen phosphate to a mixture of calcium ortho-phosphate and calcium pyrophosphate. TG-DTG shows the mineral is not stable above 111 {sup o}C. A mechanism for the formation of brushite on calcite surfaces is proposed, and this mechanism has relevance to the formation of brushite in urinary tracts.

  1. Monodisperse and size-tunable CoO nanocrystals synthesized by thermal decomposition and as an active precursor for Fischer-Tropsch synthesis

    Science.gov (United States)

    Lv, Shuai; Zhao, Xin; Xia, Guofu; Jin, Chao; Wang, Li; Yang, Weimin; Zhang, Yuhua; Li, Jinlin

    2017-01-01

    CoO nanocrystals with tunable particle sizes were prepared by thermal decomposition of cobalt(II) acetate in different long-chain alkyl amines. These alkyl amines strongly affect the coordination of the amine group to the metal atoms and the metal-amine interaction, thereby mediating the eventual particle sizes in the condensation process. Moreover, CoO nanocrystals were applied for synthesis of supported catalyst, and exhibited higher catalytic activity in Fischer-Tropsch reaction, demonstrating that nanocrystals are active precursor. The TOF of CO on CoAl-n catalyst obtained from CoO nanocrystals is ∼1.5 times higher than that on conventional catalyst with the same particle size.

  2. Synthesis of nanostructured NiO/Co3O4 through thermal decomposition of a bimetallic (Ni/Co) metal-organic framework as catalyst for cyclooctene epoxidation

    Science.gov (United States)

    Abbasi, Alireza; Soleimani, Mohammad; Najafi, Mahnaz; Geranmayeh, Shokoofeh

    2017-04-01

    Hydrothermal approach has led to the formation of a three-dimensional metal-organic framework (MOF), [NiCo(μ2-tp)(μ4-tp)(4,4‧-bpy)2]n (1) (tp = terephthalic acid and 4,4‧-bpy = 4,4‧-bipyridine) which was characterized by means of single-crystal X-ray diffraction analysis, powder X-ray diffraction (PXRD), FT-IR spectroscopy, scanning electron microscopy (SEM) and inductive coupled plasma optical emission spectroscopy (ICP-OES). Thermal decomposition of the MOF afforded nanostructured mixed metal oxide, namely NiO/Co3O4. The XRD and SEM analysis confirm the formation of the mixed metal oxide. The nanostructured NiO/Co3O4 demonstrated good catalytic activity and selectivity in the epoxidation of cyclooctene in the presence of tert-butyl hydroperoxide (TBHP) as oxidant.

  3. Ion chromatography electrospray ionization mass spectrometry method development and investigation of lithium hexafluorophosphate-based organic electrolytes and their thermal decomposition products.

    Science.gov (United States)

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Winter, Martin; Nowak, Sascha

    2014-08-08

    A method based on the coupling of ion chromatography (IC) and electrospray ionization mass spectrometry (ESI-MS) for the separation and determination of thermal decomposition products of LiPF6-based organic electrolytes is presented. The utilized electrolytes, LP30 and LP50, are commercially available and consist of 1mol/l LiPF6 dissolved in ethylene carbonate/dimethyl carbonate and ethylene carbonate/ethyl methyl carbonate, respectively. For the separation method development three ion chromatographic columns with different capacity and stationary phase were used and compared. Besides the known hydrolysis products of lithium hexafluorophosphate, several new organophosphates were separated and identified with the developed IC-ESI-MS method during aging investigations of the electrolytes. The chemical structures were elucidated with IC-ESI-MS/MS. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Preparation and formation mechanism of porous carbon nanosheets by thermal decomposition of polyvinyl alcohol films impregnated with zinc (II) and nitrate ions

    Science.gov (United States)

    Hattori, Yoshiyuki; Kojima, Rikio; Sagisaka, Kento; Umeda, Motoki; Tanaka, Toshihisa; Kondo, Atsushi; Iiyama, Taku; Kimura, Mutsumi; Fujimoto, Hiroyuki; Touhara, Hidekazu

    2017-03-01

    Porous carbon nanosheets (PCNS) with high surface areas were prepared by thermal decomposition of polyvinyl alcohol (PVA) films impregnated with Zn2+ and NO3-. Through this simple preparation method that required no additional activation processes, curved carbon nanosheets (1600 m2 g-1) and bimodal pore structure consisting of micropores and mesopores. Because of their unique structural properties, the PCNS are attractive for use as electrode materials. The electrode performance of the PCNS was investigated in 1-M tetraethylammonium tetrafluoroborate ((C2H5)4NBF4) in propylene carbonate. The PCNS electrodes displayed high specific capacitance (86 F g-1 for cations and 115 F g-1 for anions). They also showed exceptionally high rate performance with ∼90% capacitance retention at current densities up to 2 A g-1 because their nanosheet structure allowed the rapid diffusion of ions inside the electrode.

  5. Effect of high-temperature treatment in air on the surface area and porous texture of zirconium dioxide prepared by thermal decomposition of the nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Arean, C.O.; Colinas, J.M.F.; Garcia, M.A.V. (Oviedo Univ. (Spain). Dept. of Inorganic Chemistry); Arjona, A.M. (Granada Univ. (Spain). Dept. of Inorganic Chemistry)

    1982-09-01

    Zirconium dioxide, prepared by thermal decomposition of zirconium nitrate, was heated in air at temperatures ranging from 573 to 1023 K. An analysis of nitrogen adsorption-desorption isotherms on the resulting materials allowed determination of the corresponding specific surface area and porous texture. All oxides calcined within the temperature range 573 to 873 K were found to be basically mesoporous; the most frequent pore radius increasing from 3 to 10.5 nm as the temperature was raised. BET surface areas decreased across the same temperature range, from 94 down to 20 m/sup 2/ g/sup -1/. The sample fired at 1023 K showed a BET surface area smaller than 5 m/sup 2/ g/sup -1/.

  6. Acyloxyl radical pair intermediate for the initial stage of the thermal decomposition of diacyl peroxide: a density functional study

    Science.gov (United States)

    Uchimaru, Tadafumi; Hara, Ryoma; Tanabe, Kazutoshi; Fujimori, Ken

    1997-03-01

    To examine the reaction mechanism for the thermal reorganization, or more specifically the oxygen scrambling, in diacyl peroxide, we have carried out a hybrid density functional study using formyl peroxide as a model compound. The B3LYP calculations suggest that the oxygen scrambling in diacyl peroxide is most likely to occur via a σ-acyloxyl radical pair species: the competitive pathways of the [3,3]- and [1,3]-sigmatropic shifts are highly improbable. Thus, the mechanism for the thermal oxygen scrambling in diacyl peroxide should be completely different from those for the carbon counterparts of diacyl peroxide (the Cope and Claisen rearrangement).

  7. Mechanical, thermal and decomposition behavior of poly(epsilon-caprolactone) nanocomposites with clay-supported carbon nanotube hybrids

    NARCIS (Netherlands)

    Terzopoulou, Zoe; Bikiaris, Dimitrios N.; Triantafyllidis, Konstantinos S.; Potsi, Georgia; Gournis, Dimitrios; Papageorgiou, George Z.; Rudolf, Petra

    2016-01-01

    Poly(epsilon-caprolactone) (PCL) nanocomposites with hybrid clay-supported carbon nanotubes (Clay-CNT) in concentrations 0.5, 1.0 and 2.5 wt% were prepared by melt mixing. Mechanical, structural and thermal properties of the nanocomposites were studied. All nanocomposites exhibited similar

  8. Crystal structures, thermal decompositions and sensitivity properties of [Cu(ethylenediamine)2(nitroformate)2] and [Cd(ethylenediamine)3](nitroformate)2.

    Science.gov (United States)

    Yang, Li; Zhang, Jin; Zhang, Tonglai; Zhang, Jianguo; Cui, Yan

    2009-05-30

    Two new coordination compounds [Cu(ethylenediamine)(2)(nitroformate)(2)] and [Cd(ethylenediamine)(3)](nitroformate)(2) were synthesized and characterized through elemental analysis, IR and UV spectra. Their crystal structures were determined through X-ray single crystal diffraction. The first compound crystallizes in the triclinic space group P1; the second one crystallizes in the orthorhombic space group Pbca. For the first compound, central Cu(II) ion is hexa-coordinated with two ethylenediamine ligand molecules and two nitroformate anions to form the centrosymmetric octahedral structure. For the second one, central Cd(II) ion is hexa-coordinated with three ethylenediamine ligand molecules to form the slightly distorted octahedra. Through hydrogen bonds, molecules are linked together to form the three-dimensional packing diagrams. Thermal decomposition mechanisms of these two compounds were predicted through DSC, TG-DTG and FTIR analyses. In addition, the impact sensitivity, friction sensitivity and flame sensitivity were measured. All observed properties show that the first one has high energy, good thermal stability and moderate flame sensitivity.

  9. Structural insights into the thermal decomposition sequence of barium tetrahydrogenorthotellurate(VI), Ba[H{sub 4}TeO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Weil, Matthias, E-mail: Matthias.Weil@tuwien.ac.at [Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna (Austria); Stöger, Berthold [Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna (Austria); Gierl-Mayer, Christian [Institute for Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna (Austria); Libowitzky, Eugen [Institut für Mineralogie und Kristallographie, Fakultät für Geowissenschaften, Geographie und Astronomie, Universität Wien, Althanstr. 14 (UZA 2), A-1090 Vienna (Austria)

    2016-09-15

    The compounds Ba[H{sub 4}TeO{sub 6}] (I), Ba[H{sub 2}TeO{sub 5}] (II), Ba[Te{sub 2}O{sub 6}(OH){sub 2}] (III) and Ba[TeO{sub 4}] (IV) were prepared by application of a diffusion method (I), under hydrothermal conditions (II and III) and from solid state reactions (IV), respectively. Structure analysis on the basis of single crystal X-ray diffraction data revealed novel structure types for (I), (II) and (III) and isotypism of (IV) with PrSbO{sub 4} and LaSbO{sub 4}. Common feature of the four oxotellurate(VI) structures are [TeO{sub 6}] octahedra. Whereas in the crystal structure of (I) the octahedral units are isolated, they are condensed into chains via corner-sharing in (II) and via edge-sharing in (III) and (IV). The coordination numbers of the barium cations in the four structures range from seven to ten. Although hydrogen atom positions could not be located for the structures of (I) and (II), short interpolyhedral O···O contacts are evident for strong hydrogen bonding. The temperature behaviour of (I), (II) and (IV) was monitored by simultaneous thermal analysis (STA) measurements and in situ powder X-ray diffraction, revealing the decomposition sequence Ba[H{sub 4}TeO{sub 6}] → Ba[H{sub 2}TeO{sub 5}] → Ba[TeO{sub 4}]→ Ba[TeO{sub 3}] upon heating to temperatures up to 900 °C. - Graphical abstract: The crystal structures of the four oxotellurates(VI) were determined from single crystal data. The thermal decomposition of Ba[H{sub 4}TeO{sub 6}], monitored by temperature-dependent X-ray powder diffraction and simultaneous thermal analysis measurements, involves two condensation reactions according to Ba[H{sub 4}TeO{sub 6}]→Ba[H{sub 2}TeO{sub 5}]+H{sub 2}O(↑)→Ba[TeO{sub 4}]+ H{sub 2}O(↑). Display Omitted.

  10. Rate constants for the thermal decomposition of ethanol and its bimolecular reactions with OH and D : reflected shock tube and theoretical studies.

    Energy Technology Data Exchange (ETDEWEB)

    Sivaramakrishnan, R.; Su, M.-C.; Michael, J. V.; Klippenstein, S. J.; Harding, L. B.; Ruscic, B. (Chemical Sciences and Engineering Division)

    2010-09-09

    The thermal decomposition of ethanol and its reactions with OH and D have been studied with both shock tube experiments and ab initio transition state theory-based master equation calculations. Dissociation rate constants for ethanol have been measured at high T in reflected shock waves using OH optical absorption and high-sensitivity H-atom ARAS detection. The three dissociation processes that are dominant at high T are: C{sub 2}H{sub 5}OH {yields} C{sub 2}H{sub 4} + H{sub 2}O; C{sub 2}H{sub 5}OH {yields} CH{sub 3} + CH{sub 2}OH; C{sub 2}H{sub 5}OH {yields} C{sub 2}H{sub 5} + OH. The rate coefficient for reaction C was measured directly with high sensitivity at 308 nm using a multipass optical White cell. Meanwhile, H-atom ARAS measurements yield the overall rate coefficient and that for the sum of reactions B and C, since H-atoms are instantaneously formed from the decompositions of CH{sub 2}OH and C{sub 2}H{sub 5} into CH{sub 2}O + H and C{sub 2}H{sub 4} + H, respectively. By difference, rate constants for reaction 1 could be obtained. One potential complication is the scavenging of OH by unreacted ethanol in the OH experiments, and therefore, rate constants for OH + C{sub 2}H{sub 5}OH {yields} products were measured using tert-butyl hydroperoxide (tBH) as the thermal source for OH. The present experiments can be represented by the Arrhenius expression k = (2.5 {+-} 0.43) x 10{sup -11} exp(- 911 {+-} 191 K/T) cm{sup 3} molecule{sup -1} s{sup -1} over the T range 857-1297 K. For completeness, we have also measured the rate coefficient for the reaction of D atoms with ethanol D + C{sub 2}H{sub 5}OH {yields} products whose H analogue is another key reaction in the combustion of ethanol. Over the T range 1054-1359 K, the rate constants from the present experiments can be represented by the Arrhenius expression, k = (3.98 {+-} 0.76) x 10{sup -10} exp(- 4494 {+-} 235 K/T) cm{sup 3} molecule{sup -1} s{sup -1}. The high-pressure rate coefficients for reactions B and C

  11. Kinetics and the thermal decomposition of Sodium Alanate in the presence of MmNi4.5Al0.5 nanoparticles

    Science.gov (United States)

    Edla, Raju; Gangal, Aneesh C.; Manna, Joydev; Vashistha, Manvendra; Sharma, Pratibha

    2014-03-01

    Sodium Alanate (NaAlH4) is a promising hydrogen storage material due to its high hydrogen content (7.6 wt% of H2), and relatively moderate dehydrogenation and rehydrogenation temperatures. The addition of an appropriate catalyst to NaAlH4 results in a reversible release of 5.5 wt% H2 in a low temperature range of about 90 to 150 °C. Catalyst nano particles of MmNi4.5Al0.5 (henceforth referred to as Mm) to NaAlH4 were added by mechanical ball milling (BM) in mass ratios of 100:5, 100:10, and 100:20, respectively. Thermal decomposition studies were performed at various temperatures (90-150 °C) and a significant improvement in the dehydrogenation was observed after the addition of Mm to the NaAlH4. Un-doped ball milled NaAlH4 released 1.55 wt% of H2 at 150 °C in 60 min, and Mm added NaAlH4 released 3.10-3.25 wt% of H2 were released, respectively. Kinetics analysis was done by using model fit, model free fitting and the obtained activation energy values for both have shown good agreement and the possible decomposition mechanism in all samples by nucleation-growth-saturation mechanism. The improved thermodynamics and kinetics can be attributed to the uniform dispersion and catalytic effect of the Mm nanoparticles, and also to the effect of ball milling.

  12. Thermal decomposition of a hydrotalcite-containing Cu–Zn–Al precursor : thermal methods combined with an in situ DRIFT study

    NARCIS (Netherlands)

    López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

    2002-01-01

    A Cu–Zn–Al precursor (CZA) was synthesized efficiently by coprecipitation of the corresponding cations with sodium carbonate at constant pH and temperature. The starting precursor contained a mixture of two hydroxycarbonate phases: rosasite and a Cu–Zn hydrotalcite-like phase. The thermal

  13. Graph Decompositions

    DEFF Research Database (Denmark)

    Merker, Martin

    The topic of this PhD thesis is graph decompositions. While there exist various kinds of decompositions, this thesis focuses on three problems concerning edgedecompositions. Given a family of graphs H we ask the following question: When can the edge-set of a graph be partitioned so that each part...... induces a subgraph isomorphic to a member of H? Such a decomposition is called an H-decomposition. Apart from the existence of an H-decomposition, we are also interested in the number of parts needed in an H-decomposition. Firstly, we show that for every tree T there exists a constant k(T) such that every...... k(T)-edge-connected graph whose size is divisible by the size of T admits a T-decomposition. This proves a conjecture by Barát and Thomassen from 2006. Moreover, we introduce a new arboricity notion where we restrict the diameter of the trees in a decomposition into forests. We conjecture...

  14. High temperature shock tube and theoretical studies on the thermal decomposition of dimethyl carbonate and its bimolecular reactions with H and D-atoms.

    Science.gov (United States)

    Peukert, S L; Sivaramakrishnan, R; Michael, J V

    2013-05-09

    The shock tube technique was used to study the high temperature thermal decomposition of dimethyl carbonate, CH3OC(O)OCH3 (DMC). The formation of H-atoms was measured behind reflected shock waves by using atomic resonance absorption spectrometry (ARAS). The experiments span a T-range of 1053-1157 K at pressures ∼0.5 atm. The H-atom profiles were simulated using a detailed chemical kinetic mechanism for DMC thermal decomposition. Simulations indicate that the formation of H-atoms is sensitive to the rate constants for the energetically lowest-lying bond fission channel, CH3OC(O)OCH3 → CH3 + CH3OC(O)O [A], where H-atoms form instantaneously at high temperatures from the sequence of radical β-scissions, CH3OC(O)O → CH3O + CO2 → H + CH2O + CO2. A master equation analysis was performed using CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties for all thermal decomposition processes in DMC. The theoretical predictions were found to be in good agreement with the present experimentally derived rate constants for the bond fission channel (A). The theoretically derived rate constants for this important bond-fission process in DMC can be represented by a modified Arrhenius expression at 0.5 atm over the T-range 1000-2000 K as, kA(T) = 6.85 × 10(98)T (-24.239) exp(-65250 K/T) s(-1). The H-atom temporal profiles at long times show only minor sensitivity to the abstraction reaction, H + CH3OC(O)OCH3 → H2 + CH3OC(O)OCH2 [B]. However, H + DMC is an important fuel destruction reaction at high temperatures. Consequently, measurements of D-atom profiles using D-ARAS allowed unambiguous rate constant measurements for the deuterated analog of reaction B, D + CH3OC(O)OCH3 → HD + CH3OC(O)OCH2 [C]. Reaction C is a surrogate for H + DMC since the theoretically predicted kinetic isotope effect at high temperatures (1000 - 2000K) is close to unity, kC ≈ 1.2 kB. TST calculations employing CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties

  15. Synthesis, characterization and thermal decomposition of [Pd2 (C2-dmba (µ-SO4 (SO22

    Directory of Open Access Journals (Sweden)

    Caires Antonio Carlos Fávero

    1998-01-01

    Full Text Available The bridged sulphate complex [Pd2 (C²,dmba (µ-SO4 (SO22] has been obtained by reacting a saturated solution of SO2 in methanol and the cyclometallated compound [Pd(C²,N-dmba(µ-N3] 2; (dmba = N,N-dimethylbenzylamine, at room temperature for 24 h. Reaction product was characterized by elemental analysis, NMR comprising 13C{¹H} and ¹H nuclei and I.R. spectrum's measurements. Thermal behavior has been investigated and residual products identified by X-ray powder diffraction.

  16. A Monte Carlo simulation of a simplified reactor by decomposition of the neutron spectrum into fission, intermediate and thermal distributions

    Energy Technology Data Exchange (ETDEWEB)

    Barcellos, Luiz Felipe F.C.; Bodmann, Bardo E.J.; Vilhena, Marco T. de, E-mail: luizfelipe.fcb@gmail.com, E-mail: bardo.bodmann@ufrgs.br, E-mail: vilhena@mat.ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil). Grupo de Estudos Nucleares. Escola de Engenharia; Leite, Sergio Q. Bogado, E-mail: sbogado@eletronuclear.gov.br [Eletrobras Termonuclear S.A. (ELETRONUCLEAR), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    In this paper the neutron spectrum of a simulated hypothetical nuclear reactor is decomposed as a sum of three probability distributions. Two of the distributions preserve shape with time but not necessarily the integral. One of the two distributions is due to fission, i.e. high neutron energies and the second a Maxwell-Boltzmann distribution for low (thermal) neutron energies. The third distribution has an a priori unknown and possibly variable shape with time and is determined from parametrizations of Monte Carlo simulation. This procedure is effective in attaining two objectives, the first is to include effects due to up-scattering of neutrons, and the second is to optimize computational time of the stochastic method (tracking and interaction). The simulation of the reactor is done with a Monte Carlo computer code with tracking and using continuous energy dependence. This code so far computes down-scattering, but the computation of up-scattering was ignored, since it increases significantly computational processing time. In order to circumvent this problem, one may recognize that up-scattering is dominant towards the lower energy end of the spectrum, where we assume that thermal equilibrium conditions for neutrons immersed in their environment holds. The optimization may thus be achieved by calculating only the interaction rate for neutron energy gain as well as loss and ignoring tracking, i.e. up-scattering is 'simulated' by a statistical treatment of the neutron population. For the fission and the intermediate part of the neutron spectrum tracking is taken into account explicitly, where according to the criticality condition the integral of the fission spectrum may depend on time. This simulation is performed using continuous energy dependence, and as a rst case to be studied we assume a recurrent regime. The three calculated distributions are then used in the Monte Carlo code to compute the subsequent Monte Carlo steps with subsequent updates

  17. Effect of the substitutional groups on the electrochemistry, kinetic of thermal decomposition and kinetic of substitution of some uranyl Schiff base complexes

    Energy Technology Data Exchange (ETDEWEB)

    Asadi, Zahra; Nasrollahi, Rahele; Ranjkeshshorkaei, Mohammad; Firuzabadi, Fahimeh Dehghani [Shiraz Univ. (Iran, Islamic Republic of). Chemistry Dept.; Dusek, Michal; Fejfarova, Karla [ASCR, Prague (Czech Republic). Inst. of Physics

    2016-05-15

    Uranyl(VI) complexes, [UO{sub 2}(X-saloph)(solvent)], where saloph denotes N,N{sup '}-bis(salicylidene)-1,2-phenylenediamine and X = NO{sub 2}, Cl, Me, H; were synthesized and characterized by 61H NMR, IR, UV-Vis spectroscopy, thermal gravimetry (TG), cyclic voltammetry, elemental analysis (C.H.N) and X-ray crystallography. X-ray crystallography of [UO{sub 2}(4-nitro-saloph)(DMF)] revealed coordination of the uranyl by the tetradentate Schiff base ligand and one solvent molecule, resulting in seven-coordinated uranium. The complex of [UO{sub 2}(4-nitro-saloph)(DMF)] was also synthesized in nano form. Transmission electron microscopy image showed nano-particles with sizes between 30 and 35 nm. The TG method and analysis of Coats-Redfern plots revealed that the kinetics of thermal decomposition of the complexes is of the first-order in all stages. The kinetics and mechanism of the exchange reaction of the coordinated solvent with tributylphosphine was investigated by spectrophotometric method. The second-order rate constants at four temperatures and the activation parameters showed an associative mechanism for all corresponding complexes with the following trend: 4-Nitro > 4-Cl > H > 4-Me. It was concluded that the steric and electronic properties of the complexes were important for the reaction rate. For analysis of anticancer properties of uranyl Schiff base complexes, cell culture and MTT assay was carried out. These results showed a reduction of jurkat cell line concentration across the complexes.

  18. Novel Recovery of Nano-Structured Ceria (CeO2 from Ce(III-Benzoxazine Dimer Complexes via Thermal Decomposition

    Directory of Open Access Journals (Sweden)

    Nattamon Koonsaeng

    2011-07-01

    Full Text Available N,N-bis(2-hydroxybenzylalkylamines, benzoxazine dimers, are the major product produced from benzoxazine monomers on mono-functional phenol by the one  step ring opening reaction. Due to the metal responsive property of benzoxazine dimers, in this present work, N,N-bis(5-methyl-2-hydroxybenzylmethylamine (MMD, N,N-bis (5-ethyl-2-hydroxybenzylmethylamine (EMD, and N,N-bis(5-methoxy-2-hydroxybenzyl methyl amine (MeMD, are considered as novel ligands for rare earth metal ion, such as cerium(III ion. The complex formed when the clear and colorless solutions of cerium nitrate and benzoxazine dimers were mixed, results in a brown colored solution. The metal-ligand ratios determined by the molar ratio and the Job’s methods were found to be in a ratio of 1:6. To clarify the evidence of the complex formation mechanism, the interactions among protons in benzoxazine dimers both prior to and after the formation of complexes were determined by means of 1H-NMR, 2D-NMR and a computational simulation. The single phase ceria (CeO2 was successfully prepared by thermal decomposition of the Ce(III-benzoxazine dimer complexes at 600 °C for 2 h, was then characterized using XRD. In addition, the ceria powder investigated by TEM is spherical with an average diameter of 20 nm.

  19. Synthesis of MnxGa1-xFe2O4 magnetic nanoparticles by thermal decomposition method for medical diagnosis applications

    Science.gov (United States)

    Sánchez, Javier; Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Reyes-Rodríguez, Pamela Yajaira; Jasso-Terán, Rosario Argentina; Bartolo-Pérez, Pascual; De-León-Prado, Laura Elena

    2017-04-01

    In this work, the synthesis of MnxGa1-xFe2O4 (x=0-1) nanosized particles by thermal decomposition method, using tetraethylene glycol (TEG) as a reaction medium, has been performed. The crystalline structure of the inverse spinel obtained in all the cases was identified by X-ray diffraction (XRD). Vibration sample magnetometry (VSM) was used to evaluate the magnetic properties of ferrites and to demonstrate their superparamagnetic behavior and the increase of magnetization values due to the Mn2+ ions incorporation into the FeGa2O4 structure. Transmission electron microscopy, energy dispersive spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained magnetic nanoparticles (MNPs). These MNPs showed a near spherical morphology, an average particle size of 5.6±1.5 nm and a TEG coating layer on their surface. In all the cases MNPs showed no response when submitted to an alternating magnetic field (AMF, 10.2 kA/m, 354 kHz) using magnetic induction tests. These results suggest that the synthesized nanoparticles can be potential candidates for their use in biomedical areas.

  20. Thermal Decomposition Based Synthesis of Ag-In-S/ZnS Quantum Dots and Their Chlorotoxin-Modified Micelles for Brain Tumor Cell Targeting.

    Science.gov (United States)

    Chen, Siqi; Ahmadiantehrani, Mojtaba; Publicover, Nelson G; Hunter, Kenneth W; Zhu, Xiaoshan

    Cadmium-free silver-indium-sulfide (Ag-In-S or AIS) chalcopyrite quantum dots (QDs) as well as their core-shell structures (AIS/ZnS QDs) are being paid significant attention in biomedical applications because of their low toxicity and excellent optical properties. Here we report a simple and safe synthetic system to prepare high quality AIS and AIS/ZnS QDs using thermal decomposition. The synthetic system simply involves heating a mixture of silver acetate, indium acetate, and oleic acid in dodecanethiol at 170 °C to produce AIS QDs with a 13% quantum yield (QY). After ZnS shell growth, the produced AIS/ZnS QDs achieve a 41% QY. To facilitate phase transfer and bioconjugation of AIS/ZnS QDs for cellular imaging, these QDs were loaded into the core of PLGA-PEG (5k:5k) based micelles to form AIS/ZnS QD-micelles. Cellular imaging studies showed that chlorotoxin-conjugated QD-micelles can be specifically internalized into U-87 brain tumor cells. This work discloses that the scalable synthesis of AIS/ZnS QDs and the facile surface/interface chemistry for phase transfer and bioconjugation of these QDs may open an avenue for the produced QD-micelles to be applied to the detection of endogenous targets expressed on brain tumor cells, or more broadly to cell- or tissue-based diagnosis and therapy.

  1. Facile synthesis of ultrafine SnO{sub 2} nanoparticles on graphene nanosheets via thermal decomposition of tin-octoate as anode for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinkai; Xie, Sanmu; Cao, Daxian; Lu, Xuan [Xi’an Jiaotong University, State Key Lab of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy (CNRE), School of Electrical Engineering (China); Meng, Lingjie, E-mail: menglingjie@mail.xjtu.edu.cn [Xi’an Jiaotong University, Department of Chemistry, School of Science (China); Yang, Guidong [Xi’an Jiaotong University, Department of Chemical Engineering, School of Chemical Engineering and Technology (China); Wang, Hongkang, E-mail: hongkang.wang@mail.xjtu.edu.cn [Xi’an Jiaotong University, State Key Lab of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy (CNRE), School of Electrical Engineering (China)

    2016-09-15

    We demonstrate a facile synthesis of ultrafine SnO{sub 2} nanoparticles within graphene nanosheets (GNSs) via thermal decomposition of tin-octoate, in which tin-octoate is firstly blended with GNSs followed by annealing in air at a low temperature (350 °C) and a short time (1 h). As anode for lithium ion batteries, the SnO{sub 2}/GNSs displays superior cycle and rate performance, delivering reversible capacities of 803 and 682 mA h/g at current densities of 200 and 500 mA/g after 120 cycles, respectively, much higher than that of pure SnO{sub 2} and GNSs counterparts (143 and 310 mA h/g at 500 mA/g after 120 cycles, respectively). The enhanced electrochemical performance is attributed to the ultrafine SnO{sub 2} nanoparticle size and introduction of GNSs. GNSs prevent the aggregation of the ultrafine SnO{sub 2} nanoparticles, which alleviate the stress and also provide more electrochemically active sites for lithium insertion and extraction. Moreover, GNSs with large specific surface area (~363 m{sup 2}/g) act as a good electrical conductor which greatly improves the electrode conductivity and also an excellent buffer matrix to tolerate the severe volume changes originated from the Li-Sn alloying-dealloying. This work provides a straight-forward synthetic approach for the design of novel composite anode materials with superior electrochemical performance.

  2. Facile synthesis of ultrafine SnO2 nanoparticles on graphene nanosheets via thermal decomposition of tin-octoate as anode for lithium ion batteries

    Science.gov (United States)

    Wang, Jinkai; Xie, Sanmu; Cao, Daxian; Lu, Xuan; Meng, Lingjie; Yang, Guidong; Wang, Hongkang

    2016-09-01

    We demonstrate a facile synthesis of ultrafine SnO2 nanoparticles within graphene nanosheets (GNSs) via thermal decomposition of tin-octoate, in which tin-octoate is firstly blended with GNSs followed by annealing in air at a low temperature (350 °C) and a short time (1 h). As anode for lithium ion batteries, the SnO2/GNSs displays superior cycle and rate performance, delivering reversible capacities of 803 and 682 mA h/g at current densities of 200 and 500 mA/g after 120 cycles, respectively, much higher than that of pure SnO2 and GNSs counterparts (143 and 310 mA h/g at 500 mA/g after 120 cycles, respectively). The enhanced electrochemical performance is attributed to the ultrafine SnO2 nanoparticle size and introduction of GNSs. GNSs prevent the aggregation of the ultrafine SnO2 nanoparticles, which alleviate the stress and also provide more electrochemically active sites for lithium insertion and extraction. Moreover, GNSs with large specific surface area ( 363 m2/g) act as a good electrical conductor which greatly improves the electrode conductivity and also an excellent buffer matrix to tolerate the severe volume changes originated from the Li-Sn alloying-dealloying. This work provides a straight-forward synthetic approach for the design of novel composite anode materials with superior electrochemical performance.

  3. A comparative study of magnetic properties of MnFe2O4 nanoparticles prepared by thermal decomposition and solvothermal methods

    Directory of Open Access Journals (Sweden)

    B Aslibeiki

    2017-09-01

    Full Text Available A comparative study of magnetic properties of MnFe2O4 ferrite nanoparticles prepared by two different methods has been reported. The first sample (S1 was synthesized by thermal decomposition of metal nitrates. And the second sample (S2 was prepared by solvothermal method using Tri-ethylene glycol (TEG. Magnetic hysteresis loops at 300 and 5 K; magnetization and AC susceptibility measurements versus temperature confirmed the effective role of TEG on the magnetic properties of nanoparticles. The results showed that, at 300 K the saturation magnetization (MS of S2 sample is 46% greater than that of S1 sample. At 5 K, the difference in MS of the samples raised to 60%. AC susceptibility measurements at different frequencies and also magnetization versus temperature under field cooling and zero field cooling processes revealed that, the TEG molecules influence the surface spins order of S2 sample. The sample S1 showed strongly interacting superspin glass state, while the sample S2 consists of weakly interacting superparamagnetic nanoparticles.

  4. Rapid synthesis and optical properties of hematite ({alpha}-Fe{sub 2}O{sub 3}) nanostructures using a simple thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Al-Gaashani, R., E-mail: Rashad_jashani@yahoo.com [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Thamar University, Dhamar, Republic of Yemen (Yemen); Radiman, S. [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Tabet, N. [Department of Physics and Center of Research Excellence in Renewable Energy, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Daud, A.R. [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer A novel method for the synthesis of hematite nanopowder is reported. Black-Right-Pointing-Pointer The morphology of {alpha}-Fe{sub 2}O{sub 3} changed with altering the preparation temperature. Black-Right-Pointing-Pointer The coral like nano {alpha}-Fe{sub 2}O{sub 3} prepared at 500 and 600 Degree-Sign C showed novel optical behavior. Black-Right-Pointing-Pointer The coral like nano {alpha}-Fe{sub 2}O{sub 3} could be used to enhance efficiency of the solar cells. - Abstract: Hematite nanostructures were prepared by a simple technique using the thermal decomposition of iron (III) nitrate 9-hydrate at different temperatures under air atmosphere. Observations using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed that the morphology of the nanostructures changed as the temperature was varied while their size increased with increasing preparation time. Samples prepared at 300, 400, and 500 Degree-Sign C were made of particles with a quantum dots (QDs) size. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirmed that the as-synthesized powders are pure {alpha}-Fe{sub 2}O{sub 3}. The optical energy gap of the samples varied from 3.2 eV to 2.7 eV as the preparation temperature increased from 300 Degree-Sign C to 600 Degree-Sign C.

  5. Thermal Decomposition of Hydrocalumite over a Temperature Range of 400–1500°C and Its Structure Reconstruction in Water

    Directory of Open Access Journals (Sweden)

    Jiao Tian

    2014-01-01

    Full Text Available The thermal decomposition process and structure memory effect of hydrocalumite were investigated systematically for the first time over a wide temperature range of 400–1500°C. The calcined hydrocalumite samples and their rehydrated products were characterized by XRD, FT-IR, and SEM-EDX. The results show that the calcination products at temperatures ranging from 500 to 900°C are basically mayenite and lime, while one of the final products obtained by calcination at and above 1000°C is probably tricalcium aluminate (Ca3Al2O6. For the hydrocalumite samples calcined at temperatures below 1000°C, their lamellar structure can be completely recovered in deionized water at room temperature. However, the further increase of calcination temperature could impair the regeneration ability of hydrocalumite via contact with water. Upon calcination of hydrocalumite at 1000–1500°C followed by reaction with water, a stable compound tricalcium aluminate hexahydrate (Ca3Al2O6·6H2O was produced, which is the reason why less hydrocalumite could be regenerated.

  6. On the thermal decomposition pathway of coordination compounds: synthesis, crystal structures and properties of new polymorphic CuI(2-ethylpyrazine) coordination compounds

    Science.gov (United States)

    Näther, Christian; Jeß, Inke; Lehnert, Nicolai; Hinz-Hübner, Dirk

    2003-10-01

    Five new coordination compounds were prepared at room temperature in solution, under solvothermal conditions at elevated temperatures or by thermal decomposition reactions. In the amine rich 1:2 compound [(CuI) 2(2-ethylpyrazine-N) 4] ( I) discrete molecular complexes are found that consist of (CuI) 2 dimers in which each copper atom is coordinated by two 2-ethylpyrazine ligands. The crystal structure of the 1:1 compound poly[(CuI) 2( μ2-2-ethylpyrazine-N,N') 2] ( II) contains (CuI) 2 dimers which are connected by the 2-ethylpyrazine ligands into layers parallel to (010). The second modification of a 1:1 compound poly[(CuI) 2( μ2-2-ethylpyrazine-N,N')-(2-ethylpyrazine-N)] ( III) consists of 8-membered CuI rings, which are connected by the 2-ethylpyrazine ligands into layers. In one modification of poly[(CuI) 2( μ2-2-ethylpyrazine-N,N')] ( IV) CuI double chains are connected by the ligands into layers parallel to (001). If the preparation is kinetically controlled, crystals of the second modification poly[(CuI) 2( μ2-2-ethylpyrazine)-N,N'

  7. Superparamagnetic Fe3O4 Nanoparticles: Synthesis by Thermal Decomposition of Iron(III) Glucuronate and Application in Magnetic Resonance Imaging.

    Science.gov (United States)

    Patsula, Vitalii; Kosinová, Lucie; Lovrić, Marija; Ferhatovic Hamzić, Lejla; Rabyk, Mariia; Konefal, Rafal; Paruzel, Aleksandra; Šlouf, Miroslav; Herynek, Vít; Gajović, Srećko; Horák, Daniel

    2016-03-23

    Monodisperse superparamagnetic Fe3O4 nanoparticles coated with oleic acid were prepared by thermal decomposition of Fe(III) glucuronate. The shape, size, and particle size distribution were controlled by varying the reaction parameters, such as the reaction temperature, concentration of the stabilizer, and type of high-boiling-point solvents. Magnetite particles were characterized by transmission electron microscopy (TEM), as well as electron diffraction (SAED), X-ray diffraction (XRD), dynamic light scattering (DLS), and magnetometer measurements. The particle coating was analyzed by atomic absorption spectroscopy (AAS) and attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FTIR) spectroscopy. To make the Fe3O4 nanoparticles dispersible in water, the particle surface was modified with α-carboxyl-ω-bis(ethane-2,1-diyl)phosphonic acid-terminated poly(3-O-methacryloyl-α-D-glucopyranose) (PMG-P). For future practical biomedical applications, nontoxicity plays a key role, and the PMG-P&Fe3O4 nanoparticles were tested on rat mesenchymal stem cells to determine the particle toxicity and their ability to label the cells. MR relaxometry confirmed that the PMG-P&Fe3O4 nanoparticles had high relaxivity but rather low cellular uptake. Nevertheless, the labeled cells still provided visible contrast enhancement in the magnetic resonance image. In addition, the cell viability was not compromised by the nanoparticles. Therefore, the PMG-P&Fe3O4 nanoparticles have the potential to be used in biomedical applications, especially as contrast agents for magnetic resonance imaging.

  8. Synthesis, spectroscopic characterization, electrochemical behaviour and thermal decomposition studies of some transition metal complexes with an azo derivative

    Science.gov (United States)

    Sujamol, M. S.; Athira, C. J.; Sindhu, Y.; Mohanan, K.

    2010-01-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with a novel heterocyclic azo derivative, formed by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with acetylacetone were synthesized and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-vis, IR, 1H NMR and EPR spectral data. Spectral studies revealed that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated to the metal ion in a tridentate fashion. Analytical data revealed that all the complexes exhibited 1:1 metal-ligand ratio. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry was proposed for each complex. The nickel(II) complex has undergone facile transesterification reaction when refluxed in methanol for a long period. The ligand and the copper(II) complex were subjected to X-ray diffraction study. The electrochemical behaviour of copper(II) complex was investigated by cyclic voltammetry. The thermal behaviour of the same complex was also examined by thermogravimetry.

  9. Synthesis, Characterization, and Photocatalytic Behavior of Praseodymium Carbonate and Oxide Nanoparticles Obtained by Optimized Precipitation and Thermal Decomposition

    Science.gov (United States)

    Pourmortazavi, Seied Mahdi; Rahimi-Nasrabadi, Mehdi; Aghazadeh, Mustafa; Ganjali, Mohammad Reza; Sadeghpour Karimi, Meisam; Norouzi, Parviz

    2017-07-01

    Direct precipitation of insoluble praseodymium carbonate salt by reaction of the corresponding cation and anion was utilized in this study. This facile, routine, and effective route was optimized statistically through an orthogonal array design for fabrication of nanoparticles, using a Taguchi method to quantitatively evaluate the effects of the major operation conditions on the particle diameter via analysis of variance. The results indicated that high-purity particles with very small dimension (30 nm) could be produced simply by regulating the cation and anion concentrations and flow rate of introducing the cation into the anion solution. The product was thermally decomposed to yield praseodymium oxide nanoparticles by single-stage reaction. Both products were characterized using various conventional techniques including x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy to monitor the effects of the optimization on their physicochemical properties. Furthermore, the photocatalytic behavior of the nanoparticles was evaluated for treatment of water polluted with methyl orange, revealing high efficiency for degradation of the organic pollutant.

  10. In-situ formation, thermal decomposition, and adsorption studies of transition metal carbonyl complexes with short-lived radioisotopes

    Energy Technology Data Exchange (ETDEWEB)

    Even, Julia [Helmholtz-Institut Mainz (Germany); Mainz Univ. (Germany); Duellmann, Emanuel [Mainz Univ. (Germany); Helmholtz-Institut Mainz (Germany); GSI Helmholzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Yakushev, Alexander [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); and others

    2014-07-01

    We report on the in-situ synthesis of metal carbonyl complexes with short-lived isotopes of transition metals. Complexes of molybdenum, technetium, ruthenium and rhodium were synthesized by thermalisation of products of neutron-induced fission of {sup 249}Cf in a carbon monoxide-nitrogen mixture. Complexes of tungsten, rhenium, osmium, and iridium were synthesized by thermalizing short-lived isotopes produced in {sup 24}Mg-induced fusion evaporation reactions in a carbon monoxide containing atmosphere. The chemical reactions took place at ambient temperature and pressure conditions. The complexes were rapidly transported in a gas stream to collection setups or gas phase chromatography devices. The physisorption of the complexes on Au and SiO{sub 2} surfaces was studied. We also studied the stability of some of the complexes, showing that these start to decompose at temperatures above 300 C in contact with a quartz surface. Our studies lay a basis for the investigation of such complexes with transactinides.

  11. Decomposition techniques

    Science.gov (United States)

    Chao, T.T.; Sanzolone, R.F.

    1992-01-01

    Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed. ?? 1992.

  12. Method validation for control determination of mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry.

    Science.gov (United States)

    Torres, Daiane Placido; Martins-Teixeira, Maristela Braga; Cadore, Solange; Queiroz, Helena Müller

    2015-01-01

    A method for the determination of total mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) has been validated following international foodstuff protocols in order to fulfill the Brazilian National Residue Control Plan. The experimental parameters have been previously studied and optimized according to specific legislation on validation and inorganic contaminants in foodstuff. Linearity, sensitivity, specificity, detection and quantification limits, precision (repeatability and within-laboratory reproducibility), robustness as well as accuracy of the method have been evaluated. Linearity of response was satisfactory for the two range concentrations available on the TDA AAS equipment, between approximately 25.0 and 200.0 μg kg(-1) (square regression) and 250.0 and 2000.0 μg kg(-1) (linear regression) of mercury. The residues for both ranges were homoscedastic and independent, with normal distribution. Correlation coefficients obtained for these ranges were higher than 0.995. Limits of quantification (LOQ) and of detection of the method (LDM), based on signal standard deviation (SD) for a low-in-mercury sample, were 3.0 and 1.0 μg kg(-1), respectively. Repeatability of the method was better than 4%. Within-laboratory reproducibility achieved a relative SD better than 6%. Robustness of the current method was evaluated and pointed sample mass as a significant factor. Accuracy (assessed as the analyte recovery) was calculated on basis of the repeatability, and ranged from 89% to 99%. The obtained results showed the suitability of the present method for direct mercury measurement in fresh fish and shrimp samples and the importance of monitoring the analysis conditions for food control purposes. Additionally, the competence of this method was recognized by accreditation under the standard ISO/IEC 17025.

  13. Composition decomposition

    DEFF Research Database (Denmark)

    Dyson, Mark

    2003-01-01

    . Not only have design tools changed character, but also the processes associated with them. Today, the composition of problems and their decomposition into parcels of information, calls for a new paradigm. This paradigm builds on the networking of agents and specialisations, and the paths of communication...

  14. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  15. Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

    Science.gov (United States)

    Han, Haixiang; Wei, Zheng; Barry, Matthew C; Filatov, Alexander S; Dikarev, Evgeny V

    2017-05-02

    Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO2 oxide material are reported. Heterometallic compounds LiFeL3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac)3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents. The application of the unsymmetrical ligands, tbaoac (tert-butyl acetoacetate) and ptac (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate), that exhibit different bridging properties at the two ends of the ligand, allowed us to change the connectivity pattern within the heterometallic assembly. The latter was demonstrated by structural characterization of heterometallic complexes LiFe(tbaoac)3 (1) and LiFe(ptac)3 (2) that consist of discrete heterocyclic tetranuclear molecules Li2Fe2L6. The compounds are highly volatile and exhibit a congruent sublimation character. DART mass spectrometric investigation revealed the presence of heterometallic molecules in the gas phase. The positive mode spectra are dominated by the presence of [M - L]+ peaks (M = Li2Fe2L6). In accord with their discrete molecular structure, complexes 1 and 2 are highly soluble in nearly all common solvents. In order to test the retention of the heterometallic structure in solution, the diamagnetic analog of 1, LiMg(tbaoac)3 (4), has been isolated. Its tetranuclear molecular structure was found to be isomorphous to that of the iron counterpart. 1H and 7Li NMR spectroscopy unambiguously confirmed the presence of heterometallic molecules in solutions of non-coordinating solvents. The heterometallic precursor 1 was shown to exhibit clean thermal decomposition in air that results in phase-pure α-modification of layered oxide Li

  16. Synthesis and characterization of Fe{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} ferrite magnetic nanoclusters using simple thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, Ibrahim; Zamanian, Ali, E-mail: a-zamanian@merc.ac.ir; Behnamghader, Aliasghar

    2016-08-15

    This paper presents experimental results regarding the effect of the quantity of solvent on formation of the Fe–Zn ferrite nanoparticles during thermal decomposition. A ternary system of Fe{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} has been synthesized by a thermal decomposition method using metal acetylacetonate in high temperature boiling point solvent and oleic acid. The X-ray diffraction study was used to determine phase purity, crystal structure, and average crystallite size of iron–zinc ferrite nanoparticles. The average crystallite size of nanoparticles was increased from 13 nm to 37 nm as a result of reducing the solvent from 30 ml to 10 ml in a synthesis batch. The diameter of particles and morphology of the particles were determined by transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM). Mid and far Fourier transform infrared (FT-IR) measurement confirmed monophasic spinel structure of ferrite. Furthermore, the DC magnetic properties of the samples were studied using the vibrating sample magnetometer (VSM). The largest Fe–Zn ferrite nanoparticles exhibited a relatively high saturation magnetization of 96 emu/g. Moreover, Low-field AC susceptibility measurement indicated blocking temperature of nanoparticles around 170–200 K. - Highlights: • Narrow dispersed nanoclusters Fe–Zn ferrites prepared by a simple thermal decomposition route. • Increase of solvent content in reaction cause reduce the size of nanoparticles. • The XRD parameters are refined by the Rietveld method. • Saturation magnetization increases while coercivity decreases with increasing the particle size of ferrites.

  17. Catalysis mechanism of Pd-promoted γ-alumina in the thermal decomposition of methane to hydrogen: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Salam, M. Abdus; Abdullah, Bawadi, E-mail: bawadi_abdullah@utp.edu.my

    2017-02-15

    Thermo-catalytic methane decomposition to elemental hydrogen mechanism in transitional metals (Pd, Ni & Mo) promoted Al{sub 2}O{sub 3} (001) catalyst have been studied using the density functional theory (DFT). Decomposition reactions are spontaneous and favourable above 775 K for all promoter. Pd-promoted Al{sub 2}O{sub 3} (001) catalyst demonstrates a breakthrough decomposition activity in hydrogen production as compared to Ni− and Mo-promoted Al{sub 2}O{sub 3} (001) catalysts. The activation energy (E{sub a}) range of the catalysis for Pd promoted Al{sub 2}O{sub 3} (001) catalysts is 0.003–0.34 eV. Whereas, Ni and Mo promoted Al{sub 2}O{sub 3} (001) catalysts display activation energy E{sub a} in the range of 0.63–1.15 eV and 0.04–5.98 eV, respectively. Pd-promoted catalyst also shows a higher adsorption energy (−0.68 eV) and reactivity than that of Ni and Mo promoted Al{sub 2}O{sub 3} (001) catalysts. The rates of successive decomposition of methane are found to be 16.15 × 10{sup 12}, 15.95 × 10{sup 12} and 16.09 × 10{sup 12} s{sup −1} for the promoter of Pd, Ni and Mo, respectively. Pd promoted Al{sub 2}O{sub 3} (001) catalyst reduces the methane decomposition temperature (775 K) and deactivation rate significantly. The catalytic conditions and catalyst is promising in producing hydrogen to support hydrogen economy. - Highlights: • Transition metals (Pd, Ni & Mo) promoted γ-alumina catalysts are designed successfully. • Pd-promoted catalyst showed breakthrough activity in methane decomposition to hydrogen. • DFT study explored the catalysis mechanism of methane decomposition at atomic level. • Pd-promoted catalyst reduced temperature and activation barrier of methane decomposition reaction significantly.

  18. Thermoanalytical study of the decomposition of yttrium trifluoroacetate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Eloussifi, H. [GRMT, GRMT, Department of Physics, University of Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain); Laboratoire de Chimie Inorganique, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); Farjas, J., E-mail: jordi.farjas@udg.cat [GRMT, GRMT, Department of Physics, University of Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain); Roura, P. [GRMT, GRMT, Department of Physics, University of Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain); Ricart, S.; Puig, T.; Obradors, X. [Institut de Ciència de Materials de Barcelona (CSIC), Campus UAB, 08193 Bellaterra, Catalonia (Spain); Dammak, M. [Laboratoire de Chimie Inorganique, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia)

    2013-10-31

    We present the use of the thermal analysis techniques to study yttrium trifluoroacetate thin films decomposition. In situ analysis was done by means of thermogravimetry, differential thermal analysis, and evolved gas analysis. Solid residues at different stages and the final product have been characterized by X-ray diffraction and scanning electron microscopy. The thermal decomposition of yttrium trifluoroacetate thin films results in the formation of yttria and presents the same succession of intermediates than powder's decomposition, however, yttria and all intermediates but YF{sub 3} appear at significantly lower temperatures. We also observe a dependence on the water partial pressure that was not observed in the decomposition of yttrium trifluoroacetate powders. Finally, a dependence on the substrate chemical composition is discerned. - Highlights: • Thermal decomposition of yttrium trifluoroacetate films. • Very different behavior of films with respect to powders. • Decomposition is enhanced in films. • Application of thermal analysis to chemical solution deposition synthesis of films.

  19. Synthesis and characterization of nanosized Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} ferrites by both sol-gel and thermal decomposition methods

    Energy Technology Data Exchange (ETDEWEB)

    De-León-Prado, Laura Elena, E-mail: laura.elena.prado@gmail.com [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Hurtado-López, Gilberto Francisco [Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo #140, CP 25294, Saltillo, Coahuila, México (Mexico)

    2017-04-01

    This work reports the synthesis of Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanoparticles by both sol-gel and thermal decomposition methods. In order to determine the effect of synthesis conditions on the crystal structure and magnetic properties of the ferrites, the synthesis was carried out varying some parameters, including composition. By both methods it was possible to obtain ferrites having a single crystalline phase with cubic inverse spinel structure and a behavior near to that of superparamagnetic materials. Saturation magnetization values were higher for materials synthesized by sol-gel. Furthermore, in both cases particles have a spherical-like morphology and nanometric sizes (11–15 nm). Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia. - Highlights: • Mg–Mn ferrites were synthesized by sol-gel and thermal decomposition methods. • Materials showed a single cubic inverse spinel crystalline structure. • Ferrites have a soft ferrimagnetic behavior close to superparamagnetic materials.

  20. Measurement of the rate of hydrogen peroxide thermal decomposition in a shock tube using quantum cascade laser absorption near 7.7 μm

    KAUST Repository

    Sajid, Muhammad Bilal

    2013-10-24

    Hydrogen peroxide (H2O2) is formed during hydrocarbon combustion and controls the system reactivity under intermediate temperature conditions. Here, we measured the rate of hydrogen peroxide decomposition behind reflected shock waves using midinfrared absorption of H2O 2 near 7.7 μm. We performed the experiments in diluted H 2O2/Ar mixtures between 930 and 1235 K and at three different pressures (1, 2, and 10 atm). Under these conditions, the decay of hydrogen peroxide is sensitive only to the decomposition reaction rate, H 2O2 + M → 2OH + M (k1). The second-order rate coefficient at low pressures (1 and 2 atm) did not exhibit any pressure dependence, suggesting that the reaction was in the low-pressure limit. The rate data measured at 10 atm exhibited falloff behavior. The measured decomposition rates can be expressed in Arrhenius forms as follows: k1(1 and 2 atm)=10(16.29±0.12)× exp (-21993±301/T)(cm 3 mol -1s-1) k1(10 atm)=10(15.24±0.10)× exp (-19955±247/T)(cm 3 mol -1s-1) © 2013 Wiley Periodicals, Inc.

  1. Development of CdS Nanostructures by Thermal Decomposition of Aminocaproic Acid-Mixed Cd-Thiourea Complex Precursor: Structural, Optical and Photocatalytic Characterization.

    Science.gov (United States)

    Patel, Jayesh D; Mighri, Frej; Ajji, Abdellah; Chaudhuri, Tapas K

    2015-04-01

    The present work deals with two different CdS nanostructures produced via hydrothermal and solvothermal decompositions of aminocaproic acid (ACA)-mixed Cd-thiourea complex precursor at 175 °C. Both nanostructures were extensively characterized for their structural, morphological and optical properties. The powder X-ray diffraction characterization showed that the two CdS nanostructures present a wurtzite morphology. Scanning electron microscopy and energy-dispersive X-ray characterizations revealed that the hydrothermal decomposition produced well-shaped CdS flowers composed of six dendritic petals, and the solvothermal decomposition produced CdS microspheres with close stoichiometric chemical composition. The UV-vis absorption and photoluminescence spectra of CdS dendritic flowers and microsphere nanostructures showed that both nanostructures present a broad absorption between 200 and 700 nm and exhibit strong green emissions at 576 and 520 nm upon excitations at 290 nm and 260 nm, respectively. The transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) characterizations confirmed that CdS microspheres were mesoporous and were composed of small nanocrystals. A possible growth mechanism in the formation of the CdS nanostructures was proposed based on morphology evolution as a function of the reaction time. Furthermore, the as-synthesized CdS nanostructures were found to exhibit highly efficient photocatalytic activities for the degradation of methyl orange (MeO) and rhodamine B (RhB) dyes.

  2. Synthesis, crystal structure and catalytic effect on thermal decomposition of RDX and AP: An energetic coordination polymer [Pb{sub 2}(C{sub 5}H{sub 3}N{sub 5}O{sub 5}){sub 2}(NMP)·NMP]{sub n}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jin-jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Liu, Zu-Liang, E-mail: liuzl@mail.njust.edu.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Cheng, Jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Fang, Dong, E-mail: fangdong106@163.com [Yancheng Teachers College, Yancheng 224002 (China)

    2013-04-15

    An energetic lead(II) coordination polymer based on the ligand ANPyO has been synthesized and its crystal structure has been got. The polymer was characterized by FT-IR spectroscopy, elemental analysis, DSC and TG-DTG technologies. Thermal analysis shows that there are one endothermic process and two exothermic decomposition stages in the temperature range of 50–600 °C with final residues 57.09%. The non-isothermal kinetic has also been studied on the main exothermic decomposition using the Kissinger's and Ozawa–Doyle's methods, the apparent activation energy is calculated as 195.2 KJ/mol. Furthermore, DSC measurements show that the polymer has significant catalytic effect on the thermal decomposition of ammonium perchlorate. - Graphical abstract: An energetic lead(II) coordination polymer of ANPyO has been synthesized, structurally characterized and properties tested. Highlights: ► We have synthesized and characterized an energetic lead(II) coordination polymer. ► We have measured its molecular structure and thermal decomposition. ► It has significant catalytic effect on thermal decomposition of AP.

  3. Synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} magnetic nanoparticles by thermal decomposition method for medical diagnosis applications

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez, Javier, E-mail: h_javiersanchez@hotmail.com [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Reyes-Rodríguez, Pamela Yajaira; Jasso-Terán, Rosario Argentina [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Bartolo-Pérez, Pascual [CINVESTAV-IPN, Unidad Mérida, Departamento de Física Aplicada, A. P. 73 Cordemex, 97310 Mérida, Yuc., México (Mexico); De-León-Prado, Laura Elena [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico)

    2017-04-01

    In this work, the synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanosized particles by thermal decomposition method, using tetraethylene glycol (TEG) as a reaction medium, has been performed. The crystalline structure of the inverse spinel obtained in all the cases was identified by X-ray diffraction (XRD). Vibration sample magnetometry (VSM) was used to evaluate the magnetic properties of ferrites and to demonstrate their superparamagnetic behavior and the increase of magnetization values due to the Mn{sup 2+} ions incorporation into the FeGa{sub 2}O{sub 4} structure. Transmission electron microscopy, energy dispersive spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained magnetic nanoparticles (MNPs). These MNPs showed a near spherical morphology, an average particle size of 5.6±1.5 nm and a TEG coating layer on their surface. In all the cases MNPs showed no response when submitted to an alternating magnetic field (AMF, 10.2 kA/m, 354 kHz) using magnetic induction tests. These results suggest that the synthesized nanoparticles can be potential candidates for their use in biomedical areas. - Highlights: • Superparamagnetic NPs of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} were synthesized by thermal decomposition. • Saturation magnetization of MnGaFe{sub 2}O{sub 4} increases as Mn ions are increased. • Nanoparticles have a nanometric size of 5.6 nm and show no heating ability.

  4. Comparison of the thermal decomposition kinetics for charged LiMn{sub 2}O{sub 4} by TG and C80 methods

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qingsong [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China)], E-mail: pinew@ustc.edu.cn; Sun Jinhua [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China); Chen Dongliang [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China); College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Chen Chunhua [Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China)

    2009-01-22

    In order to disclose the decomposition kinetics of charged LiMn{sub 2}O{sub 4} used in lithium-ion batteries, thermogravimetric analyzer (TGA) and C80 micro-calorimeter were employed in this study. Three stages of weight loss were detected by TG and two main exothermic processes were detected by C80 micro-calorimeter for the charged LiMn{sub 2}O{sub 4}. The chemical reaction kinetics is supposed to fit by an Arrhenius law, and then the activation energy is calculated as E{sub a} = 90.4 and 140.1 kJ mol{sup -1} based on TG and C80 data, respectively. And the C80 method shows more advantages in studying the thermodynamic and kinetic parameters for both the electrodes alone and its co-existing system with electrolyte.

  5. Effect of the crosslinking degree and the nickel salt load on the thermal decomposition of poly(2-hydroxyethyl methacrylate) hydrogels and on the metal release from them.

    Science.gov (United States)

    Teijón, César; Olmo, Rosa; Blanco, M Dolores; Teijón, José M; Romero, Arturo

    2006-03-15

    Polymeric matrices of poly(2-hydroxyethyl methacrylate) (PHEMA) crosslinked with different percentages of ethylene glycol dimethacrylate (EGDMA) as well as different loads of nickel salt were synthesized. Nickel release from the polymeric systems, and their thermal stability were analyzed. A high percentage of the nickel loaded was released, although strong interactions between the polymeric matrices and the nickel ion must be established since a total nickel release did not take place. The values of the diffusion coefficients showed that nickel release depended on the amount of nickel salt loaded in the polymeric matrix and also on the crosslinking degree of the gels. On the other hand, the presence of nickel salt induced an evident thermal instability in the polymeric matrices, although all the polymeric systems can be considered thermally stable.

  6. Light-induced decomposition of indocyanine green.

    Science.gov (United States)

    Engel, Eva; Schraml, Rüdiger; Maisch, Tim; Kobuch, Karin; König, Burkhard; Szeimies, Rolf-Markus; Hillenkamp, Jost; Bäumler, Wolfgang; Vasold, Rudolf

    2008-05-01

    To investigate the light-induced decomposition of indocyanine green (ICG) and to test the cytotoxicity of light-induced ICG decomposition products. ICG in solution was irradiated with laser light, solar light, or surgical endolight. The light-induced decomposition of ICG was analyzed by high-performance liquid chromatography (HPLC) and mass spectrometry. Porcine retinal pigment epithelial (RPE) cells were incubated with the light-induced decomposition products of ICG, and cell viability was measured by trypan blue exclusion assay. Independent of the light source used, singlet oxygen (photodynamic type 2 reaction) is generated by ICG leading to dioxetanes by [2+2]-cycloaddition of singlet oxygen. These dioxetanes thermally decompose into several carbonyl compounds. The decomposition products were identified by mass spectrometry. The decomposition of ICG was inhibited by adding sodium azide, a quencher of singlet oxygen. Incubation with ICG decomposition products significantly reduced the viability of RPE cells in contrast to control cells. ICG is decomposed by light within a self-sensitized photo oxidation. The decomposition products reduce the viability of RPE cells in vitro. The toxic effects of decomposed ICG should be further investigated under in vivo conditions.

  7. Utilizing carbon dioxide as a reaction medium to mitigate production of polycyclic aromatic hydrocarbons from the thermal decomposition of styrene butadiene rubber.

    Science.gov (United States)

    Kwon, Eilhann E; Yi, Haakrho; Castaldi, Marco J

    2012-10-02

    The CO(2) cofeed impact on the pyrolysis of styrene butadiene rubber (SBR) was investigated using thermogravimetric analysis (TGA) coupled to online gas chromatography/mass spectroscopy (GC/MS). The direct comparison of the chemical species evolved from the thermal degradation of SBR in N(2) and CO(2) led to a preliminary mechanistic understanding of the formation and relationship of light hydrocarbons (C(1-4)), aromatic derivatives, and polycyclic aromatic hydrocarbons (PAHs), clarifying the role of CO(2) in the thermal degradation of SBR. The identification and quantification of over 50 major and minor chemical species from hydrogen and benzo[ghi]perylene were carried out experimentally in the temperature regime between 300 and 500 °C in N(2) and CO(2). The significant amounts of benzene derivatives from the direct bond dissociation of the backbone of SBR, induced by thermal degradation, provided favorable conditions for PAHs by the gas-phase addition reaction at a relatively low temperature compared to that with conventional fuels such as coal and petroleum-derived fuels. However, the formation of PAHs in a CO(2) atmosphere was decreased considerably (i.e., ∼50%) by the enhanced thermal cracking behavior, and the ultimate fates of these species were determined by different pathways in CO(2) and N(2) atmospheres. Consequently, this work has provided a new approach to mitigate PAHs by utilizing CO(2) as a reaction medium in thermochemical processes.

  8. Preparation of CuO nanoparticles by thermal decomposition of double-helical dinuclear copper(II Schiff-base complexes

    Directory of Open Access Journals (Sweden)

    Aliakbar Dehno Khalaji

    2015-12-01

    Full Text Available In this paper, two double helical dinuclear copper(II complexes of bis-N,O-bidentate Schiff base ligands bis(3-methoxy-N-salicylidene-4,4'-diaminodiphenylsulfone (L1 and bis(5-bromo-N-salicylidene-4,4'-diaminodiphenylsulfone (L2 were prepared and characterized by elemental analyses (CHN, as well as thermal analysis. Elemental analyses (CHN suggested that the reaction between ligands and copper salt has been occurred in 1:1 molar ratio. In these complexes the Schiff base ligands behaves as an anionic and bis-bidentate chelate and is coordinated to the copper(II ion via two phenolic oxygen and two iminic nitrogen atoms. In these double helical dinuclear complexes, each copper(II center has a pseudo-tetrahedral coordination sphere two-wrapped ligands. Thermal analysis of ligands and their complexes were studied in the range of room temperature to 750 °C with a heating rate of 10 °C min-1. TG plots show that the ligands and their complexes are thermally decomposed via 2 and 3 thermal steps, respectively. In addition, the complexes thermally decomposed in air at 520 °C for 3 h. The obtained solids characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray powder diffraction (XRD and transmission electron microscopy (TEM. The X-ray pattern result shows that the CuO nanoparticles are pure and single phase. The TEM result shows the as prepared CuO nanoparticles were very small and similar shape with particle size about

  9. Preparation, Structural Investigation and Thermal Decomposition Behavior of Two High-Nitrogen Energetic Materials: ZTO·2H{sub 2}O and ZTO(phen)·H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Cong; Huang, Jie; Zhong, Yi Tang; Xu, Kang Zhen; Zhang, Zhao [Northwest Univ., Xi' an (China); Song, Ji Rong [The Palace Museum, Beijing (China)

    2013-07-15

    Two new high-nitrogen energetic compounds ZTO·2H{sub 2}O and ZTO(phen)·H{sub 2}O have been synthesized (where ZTO = 4,4-azo-1,2,4-triazol-5-one and phen = 1,10-phenanthroline). The crystal structure, elemental analysis and IR spectroscopy are presented. Compound 1 ZTO·2H{sub 2}O crystallizes in the orthorhombic crystal system with space group Pnna and compound 2 ZTO(phen)·H{sub 2}O in the triclinic crystal system with space group P-1. In ZTO(phen)·H{sub 2}O, there is intermolecular hydrogen bonds between the -NH group of ZTO molecule (as donor) and N atom of phen molecule (as acceptor). Thermal decomposition process is studied by applying the differential scanning calorimetry (DSC) and thermo thermogravimetric differential analysis (TG-DTG). The DSC curve shows that there is one exothermic peak in ZTO·2H{sub 2}O and ZTO(phen)·H{sub 2}O, respectively. The critical temperature of thermal explosion (T{sub b}) for ZTO·2H{sub 2}O and ZTO(phen)·H{sub 2}O is 282.21 .deg. C and 195.94 .deg. C, respectively.

  10. Synthesis, DFT calculations of structure, vibrational and thermal decomposition studies of the metal complex Pb[Mn(C3H2O4)2(H2O)2].

    Science.gov (United States)

    Gil, Diego M; Carbonio, Raúl E; Gómez, María Inés

    2015-04-15

    The metallo-organic complex Pb[Mn(C3H2O4)2(H2O)2] was synthesized and characterized by IR and Raman spectroscopy and powder X-ray diffraction methods. The cell parameters for the complex were determined from powder X-ray diffraction using the autoindexing program TREOR, and refined by the Le Bail method with the Fullprof program. A hexagonal unit cell was determined with a=b=13.8366(7)Å, c=9.1454(1)Å, γ=120°. The DFT calculated geometry of the complex anion [Mn(C3H2O4)2(H2O)2](2-) is very close to the experimental data reported for similar systems. The IR and Raman spectra and the thermal analysis of the complex indicate that only one type of water molecules is present in the structure. The thermal decomposition of Pb[Mn(C3H2O4)2(H2O)2] at 700 °C in air produces PbO and Pb2MnO4 as final products. The crystal structure of the mixed oxide is very similar to that reported for Pb3O4. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Waring decompositions of monomials

    National Research Council Canada - National Science Library

    Buczyńska, Weronika; Buczyński, Jarosław; Teitler, Zach

    2013-01-01

    .... We prove that any Waring decomposition of a monomial is obtained from a complete intersection ideal, determine the dimension of the set of Waring decompositions, and give the conditions under which...

  12. Evaluation of kinetic parameters of thermal and oxidative decomposition of base oils by conventional, isothermal and modulated TGA, and pressure DSC

    Energy Technology Data Exchange (ETDEWEB)

    Gamlin, C.D.; Dutta, N.K.; Roy Choudhury, N.; Matisons, J. [Ian Wark Research Institute, University of South Australia, SA 5095 Mawson Lakes (Australia); Kehoe, D. [Castrol Australia Pty. Ltd., NSW 2161 Guildford (Australia)

    2002-09-15

    Multigrade engine oils used in today's sophisticated engines are carefully engineered products. Different ingredients, such as viscosity index improvers, dispersants, antioxidants, detergents, antiwear agents, pour point depressants, etc. are added to the base oils to improve their performance as lubricants, significantly. However, the ultimate performance of the lubricant principally depends on the quality of the base oil. Therefore, understanding the degradation behaviour of the base oil is of significant importance. In this study, the kinetic parameters of the decomposition of different types and grades of base oils (all-natural, fully synthetic and semi-synthetic) have been investigated in detail by conventional and isothermal thermogravimetric analyses (TGA) as well as modulated TGA (MTGA{sup registered}). Pressure DSC (PDSC) has been employed to evaluate the spontaneous ignition and oxidative degradation behaviour of the base oils. Base oils with higher viscosity within the same grade tend to degrade at higher temperatures. It appears that the degradation of the oils studied can be modelled by an nth-order mechanism and have similar activation energies of degradation under an inert atmosphere. The all-natural base oil ALOR100 is more resistant to oxidation than the semi-synthetic Yubase4 and fully synthetic PAO4 due to the presence of naturally occurring antioxidants.

  13. Development of a hydrophilic interaction liquid chromatography-mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology.

    Science.gov (United States)

    Yassine, Mahmoud M; Dabek-Zlotorzynska, Ewa; Celo, Valbona

    2012-03-16

    The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSD<0.5%) and peak area (RSD<3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  14. Crystal structures and thermal decomposition of permanganates AE[MnO{sub 4}]{sub 2} . n H{sub 2}O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

    2017-10-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O and Ba[MnO{sub 4}]{sub 2} are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO{sub 4}]{sub 2} a long time ago, we employed a cation-exchange column loaded with Ba{sup 2+} cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O exhibiting [CaO{sub 8}] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O with [SrO{sub 10}] polyhedra adopts the cubic space group P2{sub 1}3 with a=964.19(7) pm and Z=4. So the harder the AE{sup 2+} cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO{sub 4}]{sub 2} in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO{sub 12}] polyhedra. During the thermal decomposition of Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H{sub 2}O molecule at 157 C. The crystal structure of Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn{sub 2}O{sub 3} and the oxomanganates(III,IV) AEMn{sub 3}O{sub 6} (AE=Ca and Sr) remain as final decomposition products at 800 C

  15. Thermal decomposition of ethylene oxide on Pd(111). Comparison of the pathways for the selective oxidation of ethylene and olefin metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, R.M. (Univ. of Cambridge (United Kingdom)); Ormerod, R.M. (Univ. of Keele (United Kingdom)); Tysoe, W.T. (Univ. of Wisconsin, Milwaukee, WI (United States))

    1994-03-01

    The product distribution detected in the multimass temperature-programmed desorption of a saturated overlayer of ethylene oxide adsorbed on Pd(111) at [approximately] 180 K indicates that it decomposes to yield ethylene and acetaldehyde. These observations are interpreted by postulating that ethylene oxide reacts to form an oxymetallocycle. This is proposed to thermally decompose in a manner analogous to carbometallocycles that form during olefin metathesis catalysis by the reaction between an alkene and a surface carbene. Thus, the metallocycle can decompose to yield ethylene and deposit adsorbed atomic oxygen or undergo a [beta]-hydrogen transfer to form acetaldehyde. 25 refs., 2 figs., 1 tab.

  16. Synthesis of ZnO@γ-Fe{sub 2}O{sub 3} core–shell nanocomposites by a facile thermal decomposition approach and their application in photocatalytic degradation of congo red

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Sudheer Kumar; Jeevanandam, P., E-mail: jeevafcy@iitr.ac.in [Indian Institute of Technology Roorkee, Department of Chemistry (India)

    2016-07-15

    ZnO@γ-Fe{sub 2}O{sub 3} core–shell nanocomposites were synthesized by a facile thermal decomposition approach. ZnO nanorods were first synthesized by calcination of zinc acetate at 300 °C, in air. γ-Fe{sub 2}O{sub 3} nanoparticles were then deposited on the surface of ZnO nanorods by the thermal decomposition of iron acetylacetonate at 200 °C in diphenyl ether. The structure, composition, optical and magnetic properties of the nanocomposites were studied using an array of techniques. XRD results suggest the presence of γ-Fe{sub 2}O{sub 3} nanoparticles and ZnO, and FE-SEM images indicate formation of shell of iron oxide on the ZnO nanorods. Transmission electron microscopy studies clearly show that ZnO possesses rod morphology (length = 1.1 ± 0.1 μm, diameter = 40.1 ± 7 nm) and TEM images of the ZnO@γ-Fe{sub 2}O{sub 3} nanocomposites show uniform shell of γ-Fe{sub 2}O{sub 3} coated on the ZnO nanorods and thickness of the γ-Fe{sub 2}O{sub 3} shell varies from 10 to 20 nm. Diffuse reflectance spectra of ZnO@γ-Fe{sub 2}O{sub 3} nanocomposites reveal extended optical absorption in the visible range (400–600 nm) and photoluminescence spectra indicate that the ZnO@γ-Fe{sub 2}O{sub 3} nanocomposites exhibit enhanced defect emission. The ZnO@γ-Fe{sub 2}O{sub 3} core–shell nanocomposites show superparamagnetic behaviour at room temperature. The core–shell nanocomposites exhibit enhanced visible-light driven photocatalytic degradation of congo red in an aqueous solution as compared to pure ZnO nanorods and γ-Fe{sub 2}O{sub 3} nanoparticles. The enhanced photocatalytic activity is attributed to good visible-light absorption and effective charge separation at the interface of ZnO@γ-Fe{sub 2}O{sub 3} core–shell nanocomposites.

  17. MgCoAl and NiCoAl LDHs synthesized by the hydrothermal urea hydrolysis method: Structural characterization and thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, L.H., E-mail: lhchagas-prometro@inmetro.gov.br [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); Instituto Nacional de Metrologia Qualidade e Tecnologia, Divisão de Metrologia de Materiais, 25250-020 Duque de Caxias, RJ (Brazil); De Carvalho, G.S.G.; Do Carmo, W.R. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); San Gil, R.A.S. [Universidade Federal do Rio de Janeiro, Instituto de Química, 21949-900 Rio de Janeiro, RJ (Brazil); Chiaro, S.S.X. [PETROBRAS-CENPES, 21941-915 Rio de Janeiro, RJ (Brazil); Leitão, A.A.; Diniz, R. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); De Sena, L.A.; Achete, C.A. [Instituto Nacional de Metrologia Qualidade e Tecnologia, Divisão de Metrologia de Materiais, 25250-020 Duque de Caxias, RJ (Brazil)

    2015-04-15

    Highlights: • We synthesized MgCoAl and NiCoAl LDHs by the urea hydrolysis method. • Aluminum rich and crystalline materials have been formed. • The calcination of the LDHs generated mixed oxides with high surface areas. - Abstract: Layered double hydroxides (LDHs) with Mg/Co/Al and Ni/Co/Al were synthesized for the first time by the urea hydrolysis method. The experimental conditions promoted aluminum rich and crystalline materials. The formation of LDHs was investigated by powder X-ray diffraction (XRD), chemical analysis, solid state nuclear magnetic resonance with magic angle spinning ({sup 27}Al-MAS-NMR), simultaneous thermogravimetric/differential thermal analysis (TGA/DTA), FTIR spectroscopy, scanning electron microscopy (SEM), and N{sub 2} adsorption–desorption experiments. A single phase corresponding to LDH could be obtained in all the investigated compositions. Thermal calcination of these LDHs at 500 °C resulted in the formation of solid solutions in which Al{sup 3+} was dissolved. All the calcined materials have rock-salt like structures and high surface areas.

  18. The Influence of Temperature on the Formation of Cubic Structured CdO Nanoparticles and Their Thin Films from Bis(2-hydroxy-1-naphthaldehydatocadmium(II Complex via Thermal Decomposition Technique

    Directory of Open Access Journals (Sweden)

    Thokozani Xaba

    2017-01-01

    Full Text Available Recently, researchers have developed a great interest in the synthesis of metal oxide nanoparticles due to their potential applications in various fields of science and industry, especially in catalysis, due to their high activity. Bis(2-hydroxy-1-naphthaldehydatocadmium(II complexes were prepared and used as precursors for the synthesis of cadmium oxide nanoparticles via thermal decomposition method using HDA as a stabilizing agent. The prepared complexes were also used as single source precursors to prepare CdO thin films onto the glass substrates by spin coating and were annealed at 250, 300, and 350°C, respectively. The precursors were characterized by Fourier transform infrared (FTIR spectroscopy, elemental analysis, nuclear magnetic resonance (NMR, and thermogravimetric analysis (TGA. The synthesized CdO nanoparticles and CdO thin films were characterized by ultraviolet-visible (UV-vis spectroscopy, photoluminescence (PL, X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and atomic force microscopy (AFM.

  19. Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, L.H.; De Carvalho, G.S.G. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); San Gil, R.A.S. [Universidade Federal do Rio de Janeiro, Instituto de Química, 21949-900 Rio de Janeiro, RJ (Brazil); Chiaro, S.S.X. [PETROBRAS-CENPES, 21941-915 Rio de Janeiro, RJ (Brazil); Leitão, A.A. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); Diniz, R., E-mail: renata.diniz@ufjf.edu.br [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil)

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

  20. Spectral Decomposition Algorithm (SDA)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  1. An investigation of the decomposition mechanism of calcium carbonate

    Directory of Open Access Journals (Sweden)

    D. Wang

    2017-01-01

    Full Text Available This paper focuses on investigating the decomposition mechanism of ca lcium carbonate. The non-isothermal thermal decompositions of calcium carbonate under vacuum and flowing nitrogen atmosphere have been studied by thermogravimetric analysis. With the application of the advanced nonlinear isoconversional method, the determined activation energy for each condition is dependent on the extent of reaction. Based on the dependences, a process involving two consecutive decomposition steps has been simulated. The simulation results match the experimental results of flowing nitrogen atmosphere. Results indicate that the decomposition of calcium carbonate undergoes the process of the formation of the intermediate and metastable product.

  2. Decomposition of dioxin analogues and ablation study for carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Yamauchi, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-08-01

    Two application studies associated with the free electron laser are presented separately, which are the titles of 'Decomposition of Dioxin Analogues' and 'Ablation Study for Carbon Nanotube'. The decomposition of dioxin analogues by infrared (IR) laser irradiation includes the thermal destruction and multiple-photon dissociation. It is important for us to choose the highly absorbable laser wavelength for the decomposition. The thermal decomposition takes place by the irradiation of the low IR laser power. Considering the model of thermal decomposition, it is proposed that adjacent water molecules assist the decomposition of dioxin analogues in addition to the thermal decomposition by the direct laser absorption. The laser ablation study is performed for the aim of a carbon nanotube synthesis. The vapor by the ablation is weakly ionized in the power of several-hundred megawatts. The plasma internal energy is kept over an 8.5 times longer than the vacuum. The cluster was produced from the weakly ionized gas in the enclosed gas, which is composed of the rough particles in the low power laser more than the high power which is composed of the fine particles. (J.P.N.)

  3. Multiresolution signal decomposition schemes

    NARCIS (Netherlands)

    J. Goutsias (John); H.J.A.M. Heijmans (Henk)

    1998-01-01

    textabstract[PNA-R9810] Interest in multiresolution techniques for signal processing and analysis is increasing steadily. An important instance of such a technique is the so-called pyramid decomposition scheme. This report proposes a general axiomatic pyramid decomposition scheme for signal analysis

  4. Azimuthal decomposition of optical modes

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2012-07-01

    Full Text Available This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency...

  5. Graph Decompositions and Factorizing Permutations

    Directory of Open Access Journals (Sweden)

    Christian Capelle

    2002-12-01

    Full Text Available A factorizing permutation of a given graph is simply a permutation of the vertices in which all decomposition sets appear to be factors. Such a concept seems to play a central role in recent papers dealing with graph decomposition. It is applied here for modular decomposition and we propose a linear algorithm that computes the whole decomposition tree when a factorizing permutation is provided. This algorithm can be seen as a common generalization of Ma and Hsu for modular decomposition of chordal graphs and Habib, Huchard and Spinrad for inheritance graphs decomposition. It also suggests many new decomposition algorithms for various notions of graph decompositions.

  6. Decompositions of manifolds

    CERN Document Server

    Daverman, Robert J

    2007-01-01

    Decomposition theory studies decompositions, or partitions, of manifolds into simple pieces, usually cell-like sets. Since its inception in 1929, the subject has become an important tool in geometric topology. The main goal of the book is to help students interested in geometric topology to bridge the gap between entry-level graduate courses and research at the frontier as well as to demonstrate interrelations of decomposition theory with other parts of geometric topology. With numerous exercises and problems, many of them quite challenging, the book continues to be strongly recommended to eve

  7. alumina phase transformation from thermal decomposition

    African Journals Online (AJOL)

    HOD

    for the foreseeable future, the most important types of nanoparticles which possess high specific surface area are simple oxides such as Al2O3, which are used in established applications [6], and for sapphire crystal growth [7]. Presently, alpha-alumina (α-Al2O3) has many uses in traditional and advanced ceramics. It is an.

  8. Preparation, Structure Characterization and Thermal Decomposition ...

    African Journals Online (AJOL)

    NJD

    bDepartment of Engineering, Shijiazhuang Foreign Economy and Trade Vocational College, Shijiazhuang, 050061, People's Republic of China. cDepartment of Chemistry, Handan College, Handan, 056005, People's Republic of China. dCollege of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, ...

  9. Preparation, Structure Characterization and Thermal Decomposition ...

    African Journals Online (AJOL)

    The complex was structurally characterized by single crystal X-ray diffraction, elemental analysis,UVand IR spectroscopy, molar conductance and TG-DTG techniques. ... Each Dy(III) ion is eight-coordinated to one 1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups.

  10. Thermal Decomposition of Nitrated Tributyl Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Paddleford, D.F. [Westinghouse Savannah River Company, Aiken, SC (United States); Hou, Y.; Barefield, E.K.; Tedder, D.W.; Abdel-Khalik, S.I. [Georgia Institute of Technology, GA (United States)

    1995-01-01

    Contact between tributyl phosphate and aqueous solutions of nitric acid and/or heavy metal nitrate salts at elevated temperatures can lead to exothermic reactions of explosive violence. Even though such operations have been routinely performed safely for decades as an intrinsic part of the Purex separation processes, several so-called ``red oil`` explosions are known to have occurred in the United States, Canada, and the former Soviet Union. The most recent red oil explosion occurred at the Tomsk-7 separations facility in Siberia, in April 1993. That explosion destroyed part of the unreinforced masonry walls of the canyon-type building in which the process was housed, and allowed the release of a significant quantity of radioactive material.

  11. THERMAL DECOMPOSITION OF VINYL- AND ALLYLSILANE ...

    African Journals Online (AJOL)

    a

    Paul P. Mebe1*, John W. Fitch2 and Mark Munyai3. 1Department of Chemistry, School of Maths and Natural Sciences, University of Venda,. Limpopo, South Africa. 2Department of Chemistry, Southwest Texas State University, San Marcos, Texas 78666, USA. 3Department of Chemistry, University of Zimbabwe, Zimbabwe.

  12. Thermal steam plasma decomposition of organochlorine compounds

    Science.gov (United States)

    Surov, A. V.; Subbotin, D. I.; Popov, V. E.; Popov, S. D.; Litvyikova, A. I.; Nakonechniy, Gh V.; Serba, E. O.; Obraztsov, N. V.

    2017-11-01

    For the almost complete processing of organochlorine compounds are required a high temperature, hydrogen to produce hydrogen chloride and a high degree of mixing. Reforming chlorobenzene by steam and carbon dioxide in the presence of methane using a three-phase AC plasma torch was carried out. Soot composition was analyzed by energy dispersive X-ray analysis. The yield of soot was 0.84% wt. of raw materials, the content of chlorine in the soot was 2.08% by wt.

  13. THERMAL DECOMPOSITION OF VINYL- AND ALLYLSILANE ...

    African Journals Online (AJOL)

    a

    Samples of complexes 1a-3 were prepared by literature methods [3, 4]. Thermogravimetric analyses. Analyses were performed on a Cahn, “little gem” system with a model RM-2 electrobalance, which was calibrated with copper sulfate pentahydrate. Samples were gradually heated to 275 oC and the weight losses recorded ...

  14. Polyethylene hydroperoxide decomposition products

    National Research Council Canada - National Science Library

    Lacoste, J; Carlsson, David James (Dave); Falicki, S; Wiles, D. M

    1991-01-01

    The decomposition products from pre-oxidized, linear low-density polyethylene have been identified and quantified for films exposed in the absence of oxygen to ultra-violet irradiation, heat or γ-irradiation...

  15. Litter Decomposition Rates, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set contains decomposition rates for litter of Salicornia pacifica, Distichlis spicata, and Deschampsia cespitosa buried at 7 tidal marsh sites in 2015....

  16. Atmospheric chemistry of CF3C(O)O2 radicals. Kinetics of their reaction with NO2 and kinetics of the thermal decomposition of the product CF3C(O)O2NO2

    DEFF Research Database (Denmark)

    Wallington, T.J.; Sehested, J.; Nielsen, O.J.

    1994-01-01

    decomposition CF3C(O)O2NO2. The rate of decomposition of CF3C(O)O2NO2 was independent of the total pressure of N2 diluent over the range 100-700 Torr and was fit by the expression k-1 = (1.9(-1.5)+7.6) x 10(16) exp[(-14000 +/- 480)/T] s-1. Implications for the atmospheric chemistry of CFC replacements...

  17. Orthogonal tensor decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Tamara G. Kolda

    2000-03-01

    The authors explore the orthogonal decomposition of tensors (also known as multi-dimensional arrays or n-way arrays) using two different definitions of orthogonality. They present numerous examples to illustrate the difficulties in understanding such decompositions. They conclude with a counterexample to a tensor extension of the Eckart-Young SVD approximation theorem by Leibovici and Sabatier [Linear Algebra Appl. 269(1998):307--329].

  18. Decomposition of Copper (II) Sulfate Pentahydrate: A Sequential Gravimetric Analysis.

    Science.gov (United States)

    Harris, Arlo D.; Kalbus, Lee H.

    1979-01-01

    Describes an improved experiment of the thermal dehydration of copper (II) sulfate pentahydrate. The improvements described here are control of the temperature environment and a quantitative study of the decomposition reaction to a thermally stable oxide. Data will suffice to show sequential gravimetric analysis. (Author/SA)

  19. Descomposicion termica del diperoxido de pinacolona (3,6-diterbutil-3,6-dimetil-1,2,4,5-tetraoxaciclohexano en solución de 2-metoxietanol Thermal decomposition of pinacolone diperoxide (3,6-ditertbutyl-3,6-dimethyl-1,2,4,5-tetraoxacyclohexane in 2-methoxyethanol solution

    Directory of Open Access Journals (Sweden)

    Gladys N. Eyler

    2002-05-01

    Full Text Available The thermal decomposition reaction of pinacolone diperoxide (DPP; 0.02 mol kg-1 in 2-methoxyethanol solution studied in the temperature range of 110.0-150.0 °C, follows a first-order kinetic law up to at least 50% DPP conversion. The organic products observed were pinacolone, methane and tert-butane. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DPP in 2-methoxyethanol were calculated (deltaH# = 43.8 ± 1.0 kcal mol-1 and deltaS# = 31.9 ± 2.6 cal mol-1K-1 and compared with those obtained in other solvents to evaluate the solvent effect.

  20. Thermal decomposition of polyurethane foams for manufacturing LZSA cellular glass ceramics; Decomposicao termica de espumas de poliuretano para fabricacao de vitroceramica celular de Li{sub 2}O-ZrO{sub 2}-SiO{sub 2}-Al{sub 2}O{sub 3} (LZSA)

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Cristian Berto da [Universidade do Estado de Santa Catarina, Lages, SC (Brazil). Centro de Ciencias Agroveterinarias; Escobar, Jairo A.; Quintero, Miguel W. [Universidad de los Andes, Bogota (Colombia). Dept. de Ingenieria Mecanica; Universidad de los Andes, Bogota (Colombia). Dept. de Ingenieria Quimica; Sousa, Eliandra de; Moraes, Elisangela Guzzi de; Oliveira, Antonio Pedro Novaes de; Rambo, Carlos Renato; Hotza, Dachamir [Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil). Dept. de Engenharia Quimica]. E-mail: dhotza@gmail.com

    2007-09-15

    Characterization of the thermal decomposition of polyurethane (PUR) foams was performed by Fourier-transformed infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). Three main weight loss paths were observed by TGA, the residue being lower than 3 wt.% for 3 different PUR foams analyzed. FT-IR spectra indicated CO{sub 2}, CO, NH{sub 3} and isocyanides as main decomposition products. PUR foams of different cell sizes were immersed in a slurry of the parent glass ceramic of composition Li{sub 2}O-ZrO{sub 2}-SiO{sub 2}-Al{sub 2}O{sub 3} (LZSA) and submitted to heat treatment. The LZSA cellular glass ceramics obtained after sintering and crystallization resembled the original morphology of the PUR foams. (author)

  1. Decomposição térmica de espumas de poliuretano para fabricação de vitrocerâmica celular de Li2O-ZrO2-SiO2-Al2O3 (LZSA Thermal decomposition of polyurethane foams for manufacturing LZSA cellular glass ceramics

    Directory of Open Access Journals (Sweden)

    Cristian Berto da Silveira

    2007-10-01

    Full Text Available Characterization of the thermal decomposition of polyurethane (PUR foams was performed by Fourier-transformed infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. Three main weight loss paths were observed by TGA, the residue being lower than 3 wt.% for 3 different PUR foams analyzed. FT-IR spectra indicated CO2, CO, NH3 and isocyanides as main decomposition products. PUR foams of different cell sizes were immersed in a slurry of the parent glass ceramic of composition Li2O-ZrO2-SiO2-Al 2O3 (LZSA and submitted to heat treatment. The LZSA cellular glass ceramics obtained after sintering and crystallization resembled the original morphology of the PUR foams.

  2. Electron spin resonance in Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles synthesized with the thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, I.S., E-mail: ise@iph.krasn.ru [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Zharkov, S.M.; Pankrats, A.I. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); Vorotynov, A.M.; Tugarinov, V.I.; Ivantsov, R.D.; Petrov, D.A. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Velikanov, D.A. [Kirensky Institute of Physics, Federal Research Center KSC, Russian Academy of Sciences, Krasnoyarsk 660036 (Russian Federation); Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); Lin, Chun-Rong; Chen, Chin-Chang; Tseng, Yaw-Teng; Hsu, Hua-Shu [National Pingtung University, Pingtung City, Pingtung County 90003, Taiwan (China)

    2017-08-15

    Highlights: • Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} nanoparticles were synthesized as (1 1 1) nanocrystalline plates. • Nanoparticles tend to form stacks consisting of plates attached “face to face”. • ESR parameters demonstrate unusual temperature dependences with a kink at 120–130 K. - Abstract: In this paper, we present a study of the electron spin resonance (ESR) of nanoparticles (NPs) of Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} chalcogenides with x = 0, 0.2, and 0.4. NPs were synthesized via the thermal decomposition of metal chloride salts and selenium powder in a high-temperature organic solvent. According to the XRD and HRTEM data, the NPs were single crystalline nearly hexagonal plates with the structure close to CuCr{sub 2}Se{sub 4} (Fd-3m, a = 10.337 Å). For x = 0 and 0.2, the NPs tend to form long stacks consisting of the plates “face to face” attached to each other due to the magnetostatic interparticle interaction. Only separate NPs were observed in the case of x = 0.4. Peculiarities were revealed in the ESR temperature behavior for the NPs with x = 0 and 0.2 consistent with the features in the temperature dependences of the NPs magnetization. The non-monotonous dependence of the resonance field H{sub res} on the temperature with a kink near 130 K and the energy gap in the resonance spectrum depending on the type of nanoparticle compacting are the distinct peculiarities. One of the main factors is discussed in order to explain the peculiarities: the coexistence of two types of anisotropy in the Cu{sub 1−x}Fe{sub x}Cr{sub 2}Se{sub 4} NPs, in-plain shape anisotropy and magnetocrystalline anisotropy with four easy axes, which increases strongly with the temperature decrease.

  3. Thermal Behaviour and Detonation Characterization of N-Benzoyl-3 ...

    African Journals Online (AJOL)

    NICO

    The kinetic parameters of the intense exothermic decomposition process were obtained from the analysis of the DSC curves. The apparent ... decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic ..... Substituting the corresponding data into the Smith equation.

  4. Photodegradation at day, microbial decomposition at night - decomposition in arid lands

    Science.gov (United States)

    Gliksman, Daniel; Gruenzweig, Jose

    2014-05-01

    Our current knowledge of decomposition in dry seasons and its role in carbon turnover is fragmentary. So far, decomposition during dry seasons was mostly attributed to abiotic mechanisms, mainly photochemical and thermal degradation, while the contribution of microorganisms to the decay process was excluded. We asked whether microbial decomposition occurs during the dry season and explored its interaction with photochemical degradation under Mediterranean climate. We conducted a litter bag experiment with local plant litter and manipulated litter exposure to radiation using radiation filters. We found notable rates of CO2 fluxes from litter which were related to microbial activity mainly during night-time throughout the dry season. This activity was correlated with litter moisture content and high levels of air humidity and dew. Day-time CO2 fluxes were related to solar radiation, and radiation manipulation suggested photodegradation as the underlying mechanism. In addition, a decline in microbial activity was followed by a reduction in photodegradation-related CO2 fluxes. The levels of microbial decomposition and photodegradation in the dry season were likely the factors influencing carbon mineralization during the subsequent wet season. This study showed that microbial decomposition can be a dominant contributor to CO2 emissions and mass loss in the dry season and it suggests a regulating effect of microbial activity on photodegradation. Microbial decomposition is an important contributor to the dry season decomposition and impacts the annual litter turn-over rates in dry regions. Global warming may lead to reduced moisture availability and dew deposition, which may greatly influence not only microbial decomposition of plant litter, but also photodegradation.

  5. Estudo da eficiência de degradação de tetracloreto de carbono por plasma térmico e caracterização dos produtos formados Study on the efficiency of carbon tetrachloride decomposition in argon thermal plasma and characterization of the formed products

    Directory of Open Access Journals (Sweden)

    Péricles Inácio Khalaf

    2010-01-01

    Full Text Available Decomposition of carbon tetrachloride in a DC thermal plasma reactor was investigated in argon atmosphere. The operational parameters such as plasma torch power and argon flow rate versus CCl4 conversion were examined. The CCl4 net degradation was determined by GC-FID, the chlorine produced was quantified by iodometric titration, the solid carbon was characterised by Raman spectroscopy and by BET analysis. The solid carbon collected inside de plasma reactor was submitted to solid/liquid extraction and the desorbed species were identified by GC-MS.

  6. Decomposing Nekrasov decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, A. [ITEP,25 Bolshaya Cheremushkinskaya, Moscow, 117218 (Russian Federation); Institute for Information Transmission Problems,19-1 Bolshoy Karetniy, Moscow, 127051 (Russian Federation); National Research Nuclear University MEPhI,31 Kashirskoe highway, Moscow, 115409 (Russian Federation); Zenkevich, Y. [ITEP,25 Bolshaya Cheremushkinskaya, Moscow, 117218 (Russian Federation); National Research Nuclear University MEPhI,31 Kashirskoe highway, Moscow, 115409 (Russian Federation); Institute for Nuclear Research of Russian Academy of Sciences,6a Prospekt 60-letiya Oktyabrya, Moscow, 117312 (Russian Federation)

    2016-02-16

    AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions — this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition — into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair “interaction” is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.

  7. Symmetric Tensor Decomposition

    DEFF Research Database (Denmark)

    Brachat, Jerome; Comon, Pierre; Mourrain, Bernard

    2010-01-01

    We present an algorithm for decomposing a symmetric tensor, of dimension n and order d, as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables....... Exploiting this duality, we propose necessary and sufficient conditions for the existence of such a decomposition of a given rank, using the properties of Hankel (and quasi-Hankel) matrices, derived from multivariate polynomials and normal form computations. This leads to the resolution of systems...

  8. Carbon cluster formation during thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and 1,3,5-triamino-2,4,6-trinitrobenzene high explosives from ReaxFF reactive molecular dynamics simulations.

    Science.gov (United States)

    Zhang, Luzheng; Zybin, Sergey V; van Duin, Adri C T; Dasgupta, Siddharth; Goddard, William A; Kober, Edward M

    2009-10-08

    We report molecular dynamics (MD) simulations using the first-principles-based ReaxFF reactive force field to study the thermal decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) at various densities and temperatures. TATB is known to produce a large amount (15-30%) of high-molecular-weight carbon clusters, whereas detonation of nitramines such as HMX and RDX (1,3,5-trinitroperhydro-1,3,5-triazine) generate predominantly low-molecular-weight products. In agreement with experimental observation, these simulations predict that TATB decomposition quickly (by 30 ps) initiates the formation of large carbonaceous clusters (more than 4000 amu, or approximately 15-30% of the total system mass), and HMX decomposition leads almost exclusively to small-molecule products. We find that HMX decomposes readily on this time scale at lower temperatures, for which the decomposition rate of TATB is about an order of magnitude slower. Analyzing the ReaxFF MD results leads to the detailed atomistic structure of this carbon-rich phase of TATB and allows characterization of the kinetics and chemistry related to this phase and their dependence on system density and temperature. The carbon-rich phase formed from TATB contains mainly polyaromatic rings with large oxygen content, leading to graphitic regions. We use these results to describe the initial reaction steps of thermal decomposition of HMX and TATB in terms of the rates for forming primary and secondary products, allowing comparison to experimentally derived models. These studies show that MD using the ReaxFF reactive force field provides detailed atomistic information that explains such macroscopic observations as the dramatic difference in carbon cluster formation between TATB and HMX. This shows that ReaxFF MD captures the fundamental differences in the mechanisms of such systems and illustrates how the ReaxFF may be applied to model complex chemical phenomena

  9. Kosambi and Proper Orthogonal Decomposition

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 6. Kosambi and the Proper Orthogonal Decomposition. Roddam Narasimha. General ... Keywords. Proper orthogonal decomposition; Karhunen–Loéve expansion; statistics in function space; characteristic eddies; special calculating machines.

  10. Pressure Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E A; Zaug, J M; Burnham, A K

    2009-05-29

    The effect of pressure on the thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low to moderate pressures (i.e. between ambient pressure and 1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure enhanced autocatalysis whereas the deceleration at high pressures is attributed pressure inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both {beta} and {delta} phase HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  11. Magic Coset Decompositions

    CERN Document Server

    Cacciatori, Sergio L; Marrani, Alessio

    2013-01-01

    By exploiting a "mixed" non-symmetric Freudenthal-Rozenfeld-Tits magic square, two types of coset decompositions are analyzed for the non-compact special K\\"ahler symmetric rank-3 coset E7(-25)/[(E6(-78) x U(1))/Z_3], occurring in supergravity as the vector multiplets' scalar manifold in N=2, D=4 exceptional Maxwell-Einstein theory. The first decomposition exhibits maximal manifest covariance, whereas the second (triality-symmetric) one is of Iwasawa type, with maximal SO(8) covariance. Generalizations to conformal non-compact, real forms of non-degenerate, simple groups "of type E7" are presented for both classes of coset parametrizations, and relations to rank-3 simple Euclidean Jordan algebras and normed trialities over division algebras are also discussed.

  12. Ozone Decomposition on the Surface of Metal Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Batakliev Todor Todorov

    2014-12-01

    Full Text Available The catalytic decomposition of ozone to molecular oxygen over catalytic mixture containing manganese, copper and nickel oxides was investigated in the present work. The catalytic activity was evaluated on the basis of the decomposition coefficient which is proportional to ozone decomposition rate, and it has been already used in other studies for catalytic activity estimation. The reaction was studied in the presence of thermally modified catalytic samples operating at different temperatures and ozone flow rates. The catalyst changes were followed by kinetic methods, surface measurements, temperature programmed reduction and IR-spectroscopy. The phase composition of the metal oxide catalyst was determined by X-ray diffraction. The catalyst mixture has shown high activity in ozone decomposition at wet and dry O3/O2 gas mixtures. The mechanism of catalytic ozone degradation was suggested.

  13. Decomposition Polypropylene Plastic Waste with Pyrolysis Methode

    OpenAIRE

    Naimah, Siti; Nuraeni, Chicha; Rumondang, Irma; Jati, Bumiarto Nugroho; Ermawati, Rahyani

    2012-01-01

    Various attempts have been made to reduce plastic waste. One of the attempts is to convert plastic waste into energy sources. The process of converting waste plastics involves several stages of the process, one of which is the pyrolysis (thermal cracking). Pyrolysis is the decomposition process of plastic waste and distillation process without O2 at high temperatures (500-1000 °C). Results of pyrolysis process is solids and liquids forms. With the reactor temperature at 500 °C, pyrolysis equi...

  14. Dual Decomposition for Large-Scale Power Balancing

    DEFF Research Database (Denmark)

    Halvgaard, Rasmus; Jørgensen, John Bagterp; Vandenberghe, Lieven

    2013-01-01

    Dual decomposition is applied to power balancing of exible thermal storage units. The centralized large-scale problem is decomposed into smaller subproblems and solved locallyby each unit in the Smart Grid. Convergence is achieved by coordinating the units consumption through a negotiation...

  15. Ultrafine ferromagnetic iron oxide nanoparticles: Facile synthesis by low temperature decomposition of iron glycerolate

    Energy Technology Data Exchange (ETDEWEB)

    Bartůněk, Vilém, E-mail: vilem.bartunek@vscht.cz [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Průcha, David [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Švecová, Marie [Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Ulbrich, Pavel [Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Huber, Štěpán; Sedmidubský, David; Jankovský, Ondřej [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-09-01

    We synthesized dark colored ultrafine – sub 10 nm iron oxide nanoparticles by a facile and low temperature process based on thermal decomposition of an affordable precursor – iron glycerolate. Simultaneous thermal analysis (STA) was used to study the thermal behaviour during the decomposition. The iron glycerolate was thoroughly analysed by various methods. The size of the iron nanoparticles was determined from XRD patterns and by transmission electron microscopy (TEM) and their composition has been confirmed by XPS. Magnetic properties of the nanoparticles were studied by vibrating sample magnetometry. The prepared single phase material exhibiting ferromagnetic properties is usable in a wide range of applications and may be suitable even for large scale industrial applications. - Highlights: • Iron glycerolate prepared and characterised. • Iron oxide nanoparticles prepared by thermal decomposition of iron glycerolate. • STA used to study the decomposition. • Products characterised by XRD, XPS, FT-IR, SEM and TEM. • Magnetic behaviour of monophasic samples determined.

  16. Clustering via Kernel Decomposition

    DEFF Research Database (Denmark)

    Have, Anna Szynkowiak; Girolami, Mark A.; Larsen, Jan

    2006-01-01

    Methods for spectral clustering have been proposed recently which rely on the eigenvalue decomposition of an affinity matrix. In this work it is proposed that the affinity matrix is created based on the elements of a non-parametric density estimator. This matrix is then decomposed to obtain...... posterior probabilities of class membership using an appropriate form of nonnegative matrix factorization. The troublesome selection of hyperparameters such as kernel width and number of clusters can be obtained using standard cross-validation methods as is demonstrated on a number of diverse data sets....

  17. Mode decomposition evolution equations.

    Science.gov (United States)

    Wang, Yang; Wei, Guo-Wei; Yang, Siyang

    2012-03-01

    Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be

  18. Physico-Geometrical Kinetics of Solid-State Reactions in an Undergraduate Thermal Analysis Laboratory

    Science.gov (United States)

    Koga, Nobuyoshi; Goshi, Yuri; Yoshikawa, Masahiro; Tatsuoka, Tomoyuki

    2014-01-01

    An undergraduate kinetic experiment of the thermal decomposition of solids by microscopic observation and thermal analysis was developed by investigating a suitable reaction, applicable techniques of thermal analysis and microscopic observation, and a reliable kinetic calculation method. The thermal decomposition of sodium hydrogen carbonate is…

  19. Decomposition of nitrous oxide at medium temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, G.; Wargadalam, V.J.; Winter, F.; Hofbauer, H.

    2000-03-01

    Flow reactor experiments were done to study the decomposition of N{sub 2}O at atmospheric pressure and in a temperature range of 600--1,000 C. Dilute mixtures of N{sub 2}O with H{sub 2}, CH{sub 4}, CO with and without oxygen with N{sub 2} as carrier gas were studied. To see directly the relative importance of the thermal decomposition versus the destruction by free radicals (i.e.: H, O, OH) iodine was added to the reactant mixture suppressing the radicals' concentrations towards their equilibrium concentrations. The experimental results were discussed using a detailed chemistry model. This work shows that there are still some uncertainties regarding the kinetics of the thermal decomposition and the reaction between N{sub 2}O and the O radical. Using the recommendations applied in this work for the reaction N{sub 2}O + M {leftrightarrow} N{sub 2} + O + M and for N{sub 2}O + O {leftrightarrow} products, a good agreement with the experimental data can be obtained over a wide range of experimental conditions. The reaction between N{sub 2}O and OH is of minor importance under present conditions as stated in latest literature. The results show that N{sub 2}O + H {leftrightarrow} N{sub 2} + OH is the most important reaction in the destruction of N{sub 2}O. In the presence of oxygen it competes with H + O{sub 2} + M {leftrightarrow} HO{sub 2} + M and H + O{sub 2} {leftrightarrow} O + OH, respectively. The importance of the thermal decomposition (N{sub 2}O + M {leftrightarrow} N{sub 2} + O + M) increases with residence time. Reducing conditions and a long residence time lead to a high potential in N{sub 2}O reduction. Especially mixtures of H{sub 2}/N{sub 2}O and CO/H{sub 2}O/N{sub 2}O in nitrogen lead to a chain reaction mechanism causing a strong N{sub 2}O reduction.

  20. Thermal degradation of polymer systems having liquid crystalline oligoester segment

    Directory of Open Access Journals (Sweden)

    Renato Matroniani

    Full Text Available Abstract Block copolymers and blends comprised by liquid crystalline oligoester and polystyrene were prepared and their thermal stability were characterized by thermogravimetric analysis (TGA. The samples have shown three main decomposition temperatures due to (1 lost of flexible chain and decomposition of mesogenic segment, (2 decomposition of polystyrene and (3 final decomposition of oligoester rigid segment. Both copolymers and polymer blends presented lower thermal stability compared to polystyrene and oligoester. The residual mass after heating at 600 °C in copolymers and polymer blends were lower than those found in the oligoesters. A degradative process of aromatic segments of oligoester induced by decomposition of polystyrene is suggested.

  1. Thin-film methods for examining the decomposition chemistry of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, K.L.; Trott, W.M.; Renlund, A.M.

    1993-11-01

    Experimental techniques using thin-film samples and infrared spectroscopy have been developed to examine thermally-induced condensed-phase decomposition chemistry of explosives. Experiments with nitrocellulose (NC) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) were done to examine the effects of confining the decomposition proucts so that intimate contact was maintained with the remaining explosive during isothermal decomposition at temperatures below those of the respective DTA exotherms. The NC experiments showed that substantial NC decomposition occurred at 150C and confinement of the decomposition products influenced the decomposition reactions. Some of the mechanisms and reaction rates with confined samples compared favorably with published mechanisms and rates from unconfined samples, while other mechanisms and reaction rates differed. The TATB experiments showed that significant TATB degradation occurred at temperatures as low as 210C, and substantial degradation occurred within 24 hours at 250C which is about 80C below the temperature of the DTA exotherm for TATB.

  2. Decomposition methods for unsupervised learning

    DEFF Research Database (Denmark)

    Mørup, Morten

    2008-01-01

    This thesis presents the application and development of decomposition methods for Unsupervised Learning. It covers topics from classical factor analysis based decomposition and its variants such as Independent Component Analysis, Non-negative Matrix Factorization and Sparse Coding...... methods and clustering problems is derived both in terms of classical point clustering but also in terms of community detection in complex networks. A guiding principle throughout this thesis is the principle of parsimony. Hence, the goal of Unsupervised Learning is here posed as striving for simplicity...... in the decompositions. Thus, it is demonstrated how a wide range of decomposition methods explicitly or implicitly strive to attain this goal. Applications of the derived decompositions are given ranging from multi-media analysis of image and sound data, analysis of biomedical data such as electroencephalography...

  3. Decomposition kinetics of expanded austenite with high nitrogen contents

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    This paper addresses the decomposition kinetics of synthesized homogeneous expanded austenite formed by gaseous nitriding of stainless steel AISI 304L and AISI 316L with nitrogen contents up to 38 at.% nitrogen. Isochronal annealing experiments were carried out in both inert (N2) and reducing (H2......) atmospheres. Differential thermal analysis (DTA) and thermogravimetry were applied for identification of the decomposition reactions and X-ray diffraction analysis was applied for phase analysis. CrN precipitated upon annealing; the activation energies are 187 kJ/mol and 128 kJ/mol for AISI 316L and AISI 304L...

  4. Application of Non-Isothermal Thermogravimetric Method to Interpret the Decomposition Kinetics of , and

    Science.gov (United States)

    Pouretedal, H. R.; Ebadpour, R.

    2014-05-01

    The non-isothermal thermogravimetric method was used to study the thermal decomposition of , and at heating rates of (5, 10, 15, and 20) . The activation energy of thermal decomposition reactions was computed by isoconversional methods of Ozawa-Flynn-Wall, Kissinger-Akahiro-Sunose, and Friedman equations. Also, the kinetic triplet of the thermal decomposition of salts was determined by the model-fitting method of the modified Coats-Redfern equation. The activation energies of , and of (293 to 307, 160 to 209, and 192 to 245) , respectively, are obtained by non-isothermal isoconversional methods. The modified Coats and Redfern method showed that the most probable mechanism functions of (model A3: Arami-Erofeev equation) and (model F2: second order) can be used to predict the decomposition mechanisms of , , and , respectively.

  5. Time-resolved X-ray absorption spectroscopy for the study of solid state reactions: synthesis of nanocrystalline barium titanate and thermal decomposition of ammonium hexachlorometallate compounds; Zeitaufgeloeste Roentgenabsorptionspektroskopie zur Untersuchung von Festkoerperreaktionen: Synthese von nanokristallinem Bariumtitanat und thermische Zersetzung von Ammoniumhexachlorometallat-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Rumpf, H.

    2001-07-01

    This report presents investigations on the mechanism of two different types of solid-state reactions: At first, barium titanate nanopowders were prepared through a combined polymerization and pyrolysis of a metallo-organic precursor. The mean particle size d{sub m} could be adjusted by choosing appropriate reaction temperatures and tempering atmospheres. In the present in situ study of this particular solid-phase reaction, X-ray absorption near edge structure (XANES) spectroscopy at the Ti K and Ba L{sub 3}-edges was applied in the preparation route of BaTiO{sub 3} nanopowders. A pronounced distortion of the lattice symmetry was found to occur in very fine BaTiO{sub 3} nanopowders (d{sub m} < 20 nm). Secondly, in situ XANES investigations were carried out at the Cl K, Pd L{sub 3}, Rh L{sub 3}, and Pt L{sub 3}-edges to study the mechanism of the thermal decomposition of ammonium hexachlorometallates. The results exceed structural information obtained by in situ X-ray diffraction methods and thermal analysis. Feff8 multiple scattering simulations have been carried out to disclose new intermediate phases of unknown reference compounds. (orig.)

  6. Spectral Tensor-Train Decomposition

    DEFF Research Database (Denmark)

    Bigoni, Daniele; Engsig-Karup, Allan Peter; Marzouk, Youssef M.

    2016-01-01

    .e., the “cores”) comprising the functional TT decomposition. This result motivates an approximation scheme employing polynomial approximations of the cores. For functions with appropriate regularity, the resulting spectral tensor-train decomposition combines the favorable dimension-scaling of the TT......The accurate approximation of high-dimensional functions is an essential task in uncertainty quantification and many other fields. We propose a new function approximation scheme based on a spectral extension of the tensor-train (TT) decomposition. We first define a functional version of the TT...

  7. The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles.

    Science.gov (United States)

    Onwudiwe, Damian C; Strydom, Christien A

    2015-01-25

    Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML(1)2L(2)] (M=Cd(II), Zn(II); L(1)=N-phenyldithiocarbamate, L(2)=2,2' bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M=Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Thermal Behaviour and Detonation Characterization of N-Benzoyl-3 ...

    African Journals Online (AJOL)

    The specific heat capacity of BDNAZ was determined with a continuous Cp mode of a micro-calorimeter. The standard mole specific heat capacity ofBDNAZwas 286.31 J mol1 K–1 at 298.15 K. Using the relationship between Cp and T with the thermal decomposition parameters, the time of the thermal decomposition from ...

  9. Thermal Decompositon Studies Of Pre-Irradiated Nickel (II) Azides ...

    African Journals Online (AJOL)

    The effect of pre-irradiation on the thermal decomposition of three samples of nickel (II) azide was studied. It was found that the rates of thermal decomposition of Ni(OH)N3 increased substantially with increase in pre-irradiation dosage. The initial reaction rates change from time-dependant nucleation law for the unirradiated ...

  10. AUTONOMOUS GAUSSIAN DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Heiles, Carl [Radio Astronomy Lab, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Hennebelle, Patrick [Laboratoire AIM, Paris-Saclay, CEA/IRFU/SAp-CNRS-Université Paris Diderot, F-91191 Gif-sur Yvette Cedex (France); Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville, Socorro, NM 87801 (United States); Dickey, John, E-mail: rlindner@astro.wisc.edu [University of Tasmania, School of Maths and Physics, Private Bag 37, Hobart, TAS 7001 (Australia)

    2015-04-15

    We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.

  11. Some nonlinear space decomposition algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Xue-Cheng; Espedal, M. [Univ. of Bergen (Norway)

    1996-12-31

    Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.

  12. NRSA enzyme decomposition model data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Microbial enzyme activities measured at more than 2000 US streams and rivers. These enzyme data were then used to predict organic matter decomposition and microbial...

  13. Decomposition of Network Communication Games

    NARCIS (Netherlands)

    Dietzenbacher, Bas; Borm, Peter; Hendrickx, Ruud

    2015-01-01

    Using network control structures this paper introduces network communication games as a generalization of vertex games and edge games corresponding to communication situations and studies their decomposition into unanimity games. We obtain a relation between the dividends of the network

  14. Decomposition Bounds for Marginal MAP

    OpenAIRE

    PING, WEI; Liu,Qiang; Ihler, Alexander

    2015-01-01

    Marginal MAP inference involves making MAP predictions in systems defined with latent variables or missing information. It is significantly more difficult than pure marginalization and MAP tasks, for which a large class of efficient and convergent variational algorithms, such as dual decomposition, exist. In this work, we generalize dual decomposition to a generic power sum inference task, which includes marginal MAP, along with pure marginalization and MAP, as special cases. Our method is ba...

  15. Facility Location Using Cross Decomposition

    OpenAIRE

    Jackson, Leroy A.

    1995-01-01

    The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. Determining the best base stationing for military units can be modeled as a capacitated facility location problem with sole sourcing and multiple resource categories. Computational experience suggests that cross decomposition, a unification of Benders Decomposition and Lagrangean relaxation, is superior to other contempo...

  16. Inter-year repeatability study of volatile organic compounds from surface decomposition of human analogues.

    Science.gov (United States)

    Stadler, Sonja; Desaulniers, Jean-Paul; Forbes, Shari L

    2015-05-01

    Decomposition odour and volatile organic compounds (VOCs) have gained considerable attention recently due to their use by insects and scent detection canines to locate remains. However, a comprehensive and accurate profile of decomposition odour is yet to be confirmed. This is, in part, due to the geographical diversity in the studies conducted and the variation in the methodology and compounds being reported. To date, no repeatability studies of decomposition odour have been conducted in the same environment. In order to address this current gap in the scientific literature, this study conducted three replicate trials in order to evaluate the inter-year repeatability of the decomposition VOC profile in a southern Canadian environment. Surface decomposition trials were conducted during the spring and summer months and the VOCs were analysed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). This study was able to demonstrate that decomposition VOCs are produced consistently during their characteristic stages and that this relationship is maintained under varying environmental factors which influence the rate of decomposition. This consistent production of decomposition VOCs can lead to a better understanding of the mechanisms of soft tissue decomposition and their sources of variation, and it could potentially lead to improved applications of these compounds for the detection of decomposed remains.

  17. Modeling the Thermal Destruction of Chemical Warfare ...

    Science.gov (United States)

    Symposium Paper In the event of a terrorist attack with chemical warfare agents (CWAs), large quantities of materials, both indoor and outdoor, may be treated with thermal incineration during the site remediation process. This paper reports on a study to examine the thermal decomposition of surrogate CWAs and formation of decomposition by-products bound in model building materials (in this case, ceiling tile) in a pilot-scale rotary kiln incinerator simulator.

  18. Plasma-catalytic decomposition of TCE

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, A.; Morent, R.; De Geyter, N.; Leys, C. [Ghent Univ., Ghent (Belgium). Dept. of Applied Physics; Tuan, N.D.M.; Giraudon, J.M.; Lamonier, J.F. [Univ. des Sciences et Technologies de Lille, Villeneuve (France). Dept. de Catalyse et Chimie du Solide

    2010-07-01

    Volatile organic compounds (VOCs) are gaseous pollutants that pose an environmental hazard due to their high volatility and their possible toxicity. Conventional technologies to reduce the emission of VOCs have their advantages, but they become cost-inefficient when low concentrations have to be treated. In the past 2 decades, non-thermal plasma technology has received growing attention as an alternative and promising remediation method. Non-thermal plasmas are effective because they produce a series of strong oxidizers such as ozone, oxygen radicals and hydroxyl radicals that provide a reactive chemical environment in which VOCs are completely oxidized. This study investigated whether the combination of NTP and catalysis could improve the energy efficiency and the selectivity towards carbon dioxide (CO{sub 2}). Trichloroethylene (TCE) was decomposed by non-thermal plasma generated in a DC-excited atmospheric pressure glow discharge. The production of by-products was qualitatively investigated through FT-IR spectrometry. The results were compared with those from a catalytic reactor. The removal rate of TCE reached a maximum of 78 percent at the highest input energy. The by-products of TCE decomposition were CO{sub 2}, carbon monoxide (CO) hydrochloric acid (HCl) and dichloroacetylchloride. Combining the plasma system with a catalyst located in an oven downstream resulted in a maximum removal of 80 percent, at an energy density of 300 J/L, a catalyst temperature of 373 K and a total air flow rate of 2 slm. 14 refs., 6 figs.

  19. Radiation induced synthesis of In{sub 2}O{sub 3} nanoparticles - Part II: Synthesis of In{sub 2}O{sub 3} nanoparticles by thermal decomposition of un-irradiated and γ-irradiated indium acetylacetonate

    Energy Technology Data Exchange (ETDEWEB)

    Al-Resheedi, Ajayb Saud; Alhokbany, Norah Saad [Department of Chemistry, College of Science, King Saud University, KSU, (Saudi Arabia); Mahfouz, Refaat Mohammed, E-mail: rmhfouz@science.au.edu.eg [Chemistry Department, Faculty of Science, Assiut University, AUN, (Egypt)

    2015-09-15

    Pure cubic phase, In{sub 2}O{sub 3} nanoparticles with porous structure were synthesized by solid state thermal oxidation of un-irradiated and γ-irradiated indium acetyl acetonate in presence and absence of sodium dodecyl sulphate as surfactant. The as- synthesized In{sub 2}O{sub 3} nanoparticles were characterized by X-ray diffraction (XRD), fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transition electron microscopy (TEM) and thermogravimetry (TG). The shapes and morphologies of as- synthesized In{sub 2}O{sub 3} nanoparticles were highly affected by γ-irradiation of indium acetyl acetonate precursor and by addition of sodium dodecyl sulphate as surfactant. Calcination of un-irradiated indium acetyl acetonate precursor to 4 hours of 600 °C leads to the formation of spherical- shaped accumulative and merged In{sub 2}O{sub 3} nanoparticles with porous structure, whereas irregular porous architectures composed of pure In{sub 2}O{sub 3} nanoparticles were obtained by using γ-irradiated indium acetylacetonate precursor. The as- prepared In{sub 2}O{sub 3} nano products exhibit photoluminescence emission (PL) property and display thermal stability in a wide range of temperature (25-800 °C) which suggest possible applications in nanoscale optoelectronic devices. (author)

  20. Decomposition of silane on tungsten or other materials

    Science.gov (United States)

    Wiesmann, H.J.

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silane (SiH/sub 4/) or other gases comprising H and Si, from a W or foil heated to a temperature of about 1400 to 1600/sup 0/C, in a vacuum of about 10-/sup 6/ to 10-/sup 4/ torr. A gaseous mixture is formed of atomic hydrogen and atomic silicon. The gaseous mixture is deposited onto a substrate independent of and outside the source of thermal decomposition. Hydrogenated amorphous silicon is formed. The presence of an ammonia atmosphere in the vacuum chamber enhances the photoconductivity of the hydrogenated amorphous silicon film.

  1. Radiolysis of lignin: Prospective mechanism of high-temperature decomposition

    Science.gov (United States)

    Ponomarev, A. V.

    2017-12-01

    The range of the radiation-thermal processes resulting in conversion of lignin into monomeric phenols is considered. Statistically the most probable places of macromolecule ionization are aromatic units. Release of phenolic products from a lignin macromolecule is the multistage process beginning via fragmentation of primary cation-radicals. Reactions of electrons and small radicals with macromolecules, also as degradation of cation-radicals, result in formation of phenoxyl radicals. Macroradicals possess lower heat stability in comparison with macromolecules. Thermal decomposition of macroradicals leads to release of monohydric and dihydric phenols. The probability of benzenediols formation increases in the presence of alkanes. As noted, partial transformation of lignin into charcoal is inevitable.

  2. Thermodynamic anomaly in magnesium hydroxide decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Reis, T.A.

    1983-08-01

    The Origin of the discrepancy in the equilibrium water vapor pressure measurements for the reaction Mg(OH)/sub 2/(s) = MgO(s) + H/sub 2/O(g) when determined by Knudsen effusion and static manometry at the same temperature was investigated. For this reaction undergoing continuous thermal decomposition in Knudsen cells, Kay and Gregory observed that by extrapolating the steady-state apparent equilibrium vapor pressure measurements to zero-orifice, the vapor pressure was approx. 10/sup -4/ of that previously established by Giauque and Archibald as the true thermodynamic equilibrium vapor pressure using statistical mechanical entropy calculations for the entropy of water vapor. This large difference in vapor pressures suggests the possibility of the formation in a Knudsen cell of a higher energy MgO that is thermodynamically metastable by about 48 kJ / mole. It has been shown here that experimental results are qualitatively independent of the type of Mg(OH)/sub 2/ used as a starting material, which confirms the inferences of Kay and Gregory. Thus, most forms of Mg(OH)/sub 2/ are considered to be the stable thermodynamic equilibrium form. X-ray diffraction results show that during the course of the reaction only the equilibrium NaCl-type MgO is formed, and no different phases result from samples prepared in Knudsen cells. Surface area data indicate that the MgO molar surface area remains constant throughout the course of the reaction at low decomposition temperatures, and no significant annealing occurs at less than 400/sup 0/C. Scanning electron microscope photographs show no change in particle size or particle surface morphology. Solution calorimetric measurements indicate no inherent hgher energy content in the MgO from the solid produced in Knudsen cells. The Knudsen cell vapor pressure discrepancy may reflect the formation of a transient metastable MgO or Mg(OH)/sub 2/-MgO solid solution during continuous thermal decomposition in Knudsen cells.

  3. Abstract decomposition theorem and applications

    CERN Document Server

    Grossberg, R; Grossberg, Rami; Lessmann, Olivier

    2005-01-01

    Let K be an Abstract Elementary Class. Under the asusmptions that K has a nicely behaved forking-like notion, regular types and existence of some prime models we establish a decomposition theorem for such classes. The decomposition implies a main gap result for the class K. The setting is general enough to cover \\aleph_0-stable first-order theories (proved by Shelah in 1982), Excellent Classes of atomic models of a first order tehory (proved Grossberg and Hart 1987) and the class of submodels of a large sequentially homogenuus \\aleph_0-stable model (which is new).

  4. Photocatalytic decomposition of selected estrogens and their estrogenic activity by UV-LED irradiated TiO{sub 2} immobilized on porous titanium sheets via thermal-chemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Arlos, Maricor J., E-mail: mjarlos@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Liang, Robert; Hatat-Fraile, Melisa M. [Centre for Advanced Materials Joining, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Bragg, Leslie M. [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Zhou, Norman Y. [Centre for Advanced Materials Joining, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Servos, Mark R. [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Andrews, Susan A. [Civil Engineering Department, University of Toronto, Toronto, Ontario M5S 1A4 (Canada)

    2016-11-15

    Highlights: • TiO{sub 2} self-assembled on oxidized porous titanium sheets. • UV-LED/TiO{sub 2} membrane treatment reduced the concentrations of estrogens. • Different pH conditions affect treatment efficiency. • The estrogenic activity removal was similar to the chemical disappearance. - Abstract: The removal of endocrine disrupting compounds (EDCs) remains a big challenge in water treatment. Risks associated with these compounds are not clearly defined and it is important that the water industry has additional options to increase the resiliency of water treatment systems. Titanium dioxide (TiO{sub 2}) has potential applications for the removal of EDCs from water. TiO{sub 2} has been immobilized on supports using a variety of synthesis methods to increase its feasibility for water treatment. In this study, we immobilized TiO{sub 2} through the thermal-chemical oxidation of porous titania sheets. The efficiency of the material to degrade target EDCs under UV-LED irradiation was examined under a wide range of pH conditions. A yeast-estrogen screen assay was used to complement chemical analysis in assessing removal efficiency. All compounds but 17β-estradiol were degraded and followed a pseudo first-order kinetics at all pH conditions tested, with pH 4 and pH 11 showing the most and the least efficient treatments respectively. In addition, the total estrogenic activity was substantially reduced even with the inefficient degradation of 17β-estradiol. Additional studies will be required to optimize different treatment conditions, UV-LED configurations, and membrane fouling mitigation measures to make this technology a more viable option for water treatment.

  5. Probability inequalities for decomposition integrals

    Czech Academy of Sciences Publication Activity Database

    Agahi, H.; Mesiar, Radko

    2017-01-01

    Roč. 315, č. 1 (2017), s. 240-248 ISSN 0377-0427 Institutional support: RVO:67985556 Keywords : Decomposition integral * Superdecomposition integral * Probability inequalities Subject RIV: BA - General Mathematics Impact factor: 1.357, year: 2016 http:// library .utia.cas.cz/separaty/2017/E/mesiar-0470959.pdf

  6. Wavefront reconstruction by modal decomposition

    CSIR Research Space (South Africa)

    Schulze, C

    2012-08-01

    Full Text Available We propose a new method to determine the wavefront of a laser beam based on modal decomposition by computer-generated holograms. The hologram is encoded with a transmission function suitable for measuring the amplitudes and phases of the modes...

  7. Torsion and Open Book Decompositions

    OpenAIRE

    Etnyre, John B.; Vela-Vick, David Shea

    2009-01-01

    We show that if (B,\\pi) is an open book decomposition of a contact 3-manifold (Y,\\xi), then the complement of the binding B has no Giroux torsion. We also prove the sutured Heegaard-Floer c-bar invariant of the binding of an open book is non-zero.

  8. Modular Decomposition of Boolean Functions

    NARCIS (Netherlands)

    J.C. Bioch (Cor)

    2002-01-01

    textabstractModular decomposition is a thoroughly investigated topic in many areas such as switching theory, reliability theory, game theory and graph theory. Most appli- cations can be formulated in the framework of Boolean functions. In this paper we give a uni_ed treatment of modular

  9. Decomposition of network communication games

    NARCIS (Netherlands)

    Dietzenbacher, Bas; Borm, Peter; Hendrickx, Ruud

    Using network control structures, this paper introduces a general class of network communication games and studies their decomposition into unanimity games. We obtain a relation between the dividends in any network communication game and its underlying transferable utility game, which depends on the

  10. A MEMS methanol reformer heated by decomposition of hydrogen peroxide.

    Science.gov (United States)

    Kim, Taegyu; Hwang, Jin Soo; Kwon, Sejin

    2007-07-01

    This paper presents the design, fabrication and evaluation of a micro methanol reformer complete with a heat source. The micro system consists of the steam reforming reactor of methanol, the catalytic decomposition reactor of hydrogen peroxide, and a heat exchanger between the two reactors. In the present study, catalytic decomposition of hydrogen peroxide is used as a process to supply heat to the reforming reactor. The decomposition process of hydrogen peroxide produces water vapor and oxygen as a product that can be used efficiently to operate the reformer/PEMFC system. Cu/ZnO was selected as a catalyst for methanol steam reforming and Pt for the decomposition of hydrogen peroxide. Incipient wetness method was used to load catalysts on a porous support. Catalyst loaded supports were inserted in the cavity made on the glass wafer. The performance of the methanol steam reforming system was measured at various test conditions and the optimum operation condition was sought. At the optimum condition, the hydrogen selectivity was 86.4% and the thermal efficiency was 44.8%. The product gas included 74.1% H(2), 24.5% CO(2) and 1.4% CO and the total volume production rate was 23.5 ml min(-1). This amount of hydrogen can produce 1.5 W of power on a typical PEMFC.

  11. Kinetics of non-isothermal decomposition of cinnamic acid

    Science.gov (United States)

    Zhao, Ming-rui; Qi, Zhen-li; Chen, Fei-xiong; Yue, Xia-xin

    2014-07-01

    The thermal stability and kinetics of decomposition of cinnamic acid were investigated by thermogravimetry and differential scanning calorimetry at four heating rates. The activation energies of this process were calculated from analysis of TG curves by methods of Flynn-Wall-Ozawa, Doyle, Distributed Activation Energy Model, Šatava-Šesták and Kissinger, respectively. There are only one stage of thermal decomposition process in TG and two endothermic peaks in DSC. For this decomposition process of cinnamic acid, E and log A[s-1] were determined to be 81.74 kJ mol-1 and 8.67, respectively. The mechanism was Mampel Power law (the reaction order, n = 1), with integral form G(α) = α (α = 0.1-0.9). Moreover, thermodynamic properties of Δ H ≠, Δ S ≠, Δ G ≠ were 77.96 kJ mol-1, -90.71 J mol-1 K-1, 119.41 kJ mol-1.

  12. Decomposition Mechanism and Decomposition Promoting Factors of Waste Hard Metal for Zinc Decomposition Process (ZDP)

    Energy Technology Data Exchange (ETDEWEB)

    Pee, J H; Kim, Y J; Kim, J Y; Cho, W S; Kim, K J [Whiteware Ceramic Center, KICET (Korea, Republic of); Seong, N E, E-mail: pee@kicet.re.kr [Recytech Korea Co., Ltd. (Korea, Republic of)

    2011-10-29

    Decomposition promoting factors and decomposition mechanism in the zinc decomposition process of waste hard metals which are composed mostly of tungsten carbide and cobalt were evaluated. Zinc volatility amount was suppressed and zinc steam pressure was produced in the reaction graphite crucible inside an electric furnace for ZDP. Reaction was done for 2 hrs at 650 deg. C, which 100% decomposed the waste hard metals that were over 30 mm thick. As for the separation-decomposition of waste hard metals, zinc melted alloy formed a liquid composed of a mixture of {gamma}-{beta}1 phase from the cobalt binder layer (reaction interface). The volume of reacted zone was expanded and the waste hard metal layer was decomposed-separated horizontally from the hard metal. Zinc used in the ZDP process was almost completely removed-collected by decantation and volatilization-collection process at 1000 deg. C. The small amount of zinc remaining in the tungsten carbide-cobalt powder which was completely decomposed was fully removed by using phosphate solution which had a slow cobalt dissolution speed.

  13. Analysis of thermally-degrading, confined HMX

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Schmitt, R.G.; Renlund, A.M.

    1996-12-01

    The response of a thermally-degrading, confined HMX pellet is analyzed using a Reactive Elastic-Plastic (REP) constitutive model which is founded on the collapse and growth of internal inclusions resulting from physical and chemical processes such as forced displacement, thermal expansion, and/or decomposition. Axial stress predictions compare adequately to data. Deficiencies in the model and future directions are discussed.

  14. Erbium hydride thermal desorption : controlling kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2007-08-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report show that hydride film processing parameters directly impact thermal stability. Issues to be addressed include desorption kinetics for dihydrides and trihydrides, and the effect of film growth parameters, loading parameters, and substrate selection on desorption kinetics.

  15. Pressure-Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

    Science.gov (United States)

    Glascoe, Elizabeth A.; Zaug, Joseph M.; Burnham, Alan K.

    2009-10-01

    The effect of pressure on the global thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Global decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low-to-moderate pressures (i.e., between ambient pressure and 0.1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure-enhanced autocatalysis, whereas the deceleration at high pressures is attributed to pressure-inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both the β- and δ-polymorphs of HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  16. Pressure-dependent decomposition kinetics of the energetic material HMX up to 3.6 GPa.

    Science.gov (United States)

    Glascoe, Elizabeth A; Zaug, Joseph M; Burnham, Alan K

    2009-12-03

    The effect of pressure on the global thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Global decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low-to-moderate pressures (i.e., between ambient pressure and 0.1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure-enhanced autocatalysis, whereas the deceleration at high pressures is attributed to pressure-inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both the beta- and delta-polymorphs of HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  17. A review of plutonium oxalate decomposition reactions and effects of decomposition temperature on the surface area of the plutonium dioxide product

    Science.gov (United States)

    Orr, R. M.; Sims, H. E.; Taylor, R. J.

    2015-10-01

    Plutonium (IV) and (III) ions in nitric acid solution readily form insoluble precipitates with oxalic acid. The plutonium oxalates are then easily thermally decomposed to form plutonium dioxide powder. This simple process forms the basis of current industrial conversion or 'finishing' processes that are used in commercial scale reprocessing plants. It is also widely used in analytical or laboratory scale operations and for waste residues treatment. However, the mechanisms of the thermal decompositions in both air and inert atmospheres have been the subject of various studies over several decades. The nature of intermediate phases is of fundamental interest whilst understanding the evolution of gases at different temperatures is relevant to process control. The thermal decomposition is also used to control a number of powder properties of the PuO2 product that are important to either long term storage or mixed oxide fuel manufacturing. These properties are the surface area, residual carbon impurities and adsorbed volatile species whereas the morphology and particle size distribution are functions of the precipitation process. Available data and experience regarding the thermal and radiation-induced decompositions of plutonium oxalate to oxide are reviewed. The mechanisms of the thermal decompositions are considered with a particular focus on the likely redox chemistry involved. Also, whilst it is well known that the surface area is dependent on calcination temperature, there is a wide variation in the published data and so new correlations have been derived. Better understanding of plutonium (III) and (IV) oxalate decompositions will assist the development of more proliferation resistant actinide co-conversion processes that are needed for advanced reprocessing in future closed nuclear fuel cycles.

  18. Variance decomposition in stochastic simulators

    KAUST Repository

    Le Maître, O. P.

    2015-06-28

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  19. Thermal decomposition of torrefied and carbonized briquettes of residues from coffee grain processing Decomposição térmica de briquetes torrificados e carbonizados de resíduos do processamento dos grãos de café

    Directory of Open Access Journals (Sweden)

    Thiago de Paula Protásio

    2013-06-01

    Full Text Available The use of biomass has been recognized as a potential renewable energy and an alternative substitute that contributes to the decrease of fossil fuels consumption. Therefore, this research aimed to analyze the thermal behavior of briquettes made of residues from coffee grain processing in different conditions: in natura, torrefied and carbonized. Eucalyptus sawdust was used for comparison. The briquettes were carbonized considering final temperature of 450° C (kept for 30 min. The briquettes torrefaction was performed in an electric oven (muffle using two heating rates until 250° C (kept 60 min. The thermal-gravimetric analysis was made in nitrogen atmosphere until the temperature of 600° C. The contents of fixed carbon and volatile matter of the fuels were determined. The carbonized briquette of residues from coffee grain processing presented higher stability and low thermal decomposition. It was observed a low influence of torrefaction heating rate under thermal properties of briquettes, and fixed carbon and volatile matter content. Regarding the raw biomass, lower total mass loss was observed for the residues from coffee grain processing when compared to Eucalyptus sawdust. The carbonized and torrefied briquettes presented higher hydrophobicity than raw briquettes.O uso da biomassa tem sido reconhecido como uma energia potencial renovável e um substituto alternativo que contribua para a redução do consumo de combustíveis fósseis. Portanto, objetivou-se analisar o comportamento térmico de briquetes de resíduos do processamento dos grãos de café, em diferentes formas: in natura, torrificados e carbonizados. Utilizou-se a serragem de Eucalyptus como parâmetro de comparação. Os briquetes foram carbonizados considerando a temperatura final de 450° C (mantida por 30 min. A torrefação dos briquetes foi realizada em uma mufla em duas taxas de aquecimento até 250° C (mantida por 60 min. Realizou-se a análise termogravimétrica em

  20. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...... in the combustion chamber and the cyclone was calculated taking three mechanisms into account: Reduction by char, catalytic decomposition over bed material and thermal decomposition. The calculated destruction rate was in good agreement with the measured destruction of N2O injected at different levels in the boiler...

  1. Thermic decomposition of biphenyl; Decomposition thermique du biphenyle

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-03-01

    Liquid and vapour phase pyrolysis of very pure biphenyl obtained by methods described in the text was carried out at 400 C in sealed ampoules, the fraction transformed being always less than 0.1 per cent. The main products were hydrogen, benzene, terphenyls, and a deposit of polyphenyls strongly adhering to the walls. Small quantities of the lower aliphatic hydrocarbons were also found. The variation of the yields of these products with a) the pyrolysis time, b) the state (gas or liquid) of the biphenyl, and c) the pressure of the vapour was measured. Varying the area and nature of the walls showed that in the absence of a liquid phase, the pyrolytic decomposition takes place in the adsorbed layer, and that metallic walls promote the reaction more actively than do those of glass (pyrex or silica). A mechanism is proposed to explain the results pertaining to this decomposition in the adsorbed phase. The adsorption seems to obey a Langmuir isotherm, and the chemical act which determines the overall rate of decomposition is unimolecular. (author) [French] Du biphenyle tres pur, dont la purification est decrite, est pyrolyse a 400 C en phase vapeur et en phase liquide dans des ampoules scellees sous vide, a des taux de decomposition n'ayant jamais depasse 0,1 pour cent. Les produits provenant de la pyrolyse sont essentiellement: l' hydrogene, le benzene, les therphenyles, et un depot de polyphenyles adherant fortement aux parois. En plus il se forme de faibles quantites d'hydrocarbures aliphatiques gazeux. On indique la variation des rendements des differents produits avec la duree de pyrolyse, l'etat gazeux ou liquide du biphenyle, et la pression de la vapeur. Variant la superficie et la nature des parois, on montre qu'en absence de liquide la pyrolyse se fait en phase adsorbee. La pyrolyse est plus active au contact de parois metalliques que de celles de verres (pyrex ou silice). A partir des resultats experimentaux un mecanisme de

  2. Exothermic or Endothermic Decomposition of Disubstituted Tetrazoles Tuned by Substitution Fashion and Substituents.

    Science.gov (United States)

    Jia, Yu-Hui; Yang, Kai-Xiang; Chen, Shi-Lu; Huang, Mu-Hua

    2018-01-11

    Nitrogen-rich compounds such as tetrazoles are widely used as candidates in gas-generating agents. However, the details of the differentiation of the two isomers of disubstituted tetrazoles are rarely studied, which is very important information for designing advanced materials based on tetrazoles. In this article, pairs of 2,5- and 1,5-disubstituted tetrazoles were carefully designed and prepared for study on their thermal decomposition behavior. Also, the substitution fashion of 2,5- and 1,5- and the substituents at C-5 position were found to affect the endothermic or exothermic properties. This is for the first time to the best of our knowledge that the thermal decomposition properties of different tetrazoles could be tuned by substitution ways and substitute groups, which could be used as a useful platform to design advanced materials for temperature-dependent rockets. The aza-Claisen rearrangement was proposed to understand the endothermic decomposition behavior.

  3. Thermal Conversion of Methane to Acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C; Swank, William David

    2000-01-01

    This report describes the experimental demonstration of a process for the direct thermal conversion of methane to acetylene. The process utilizes a thermal plasma heat source to dissociation products react to form a mixture of acetylene and hydrogen. The use of a supersonic expansion of the hot gas is investigated as a method of rapidly cooling (quenching) the product stream to prevent further reaction or thermal decomposition of the acetylene which can lower the overall efficiency of the process.

  4. Thermal Decomposition of Tetrazene at 90 deg C

    Science.gov (United States)

    1978-03-01

    led to its widespread use in percussion primer and stab detonator mixtures. In a recent study [1] it was concluded that the very low mechanical...Superintendent, Aeronatical Research Laboratories Senior Librarian, Defence Res rch Centre , Salisbury Librarian, R.A.N. Research Labdratory Document...Exchange Centre , DIR (16 copies) Principal Librarian, Campbell Park Library ADSATIS Annex Central Office, Directorate of Quality Assurance - Air Force

  5. Thermal decomposition of Co–Al layered double hydroxide ...

    Indian Academy of Sciences (India)

    Administrator

    All other reflections are extinguished on account of (i) turbostratic disorder which destroys all hkl reflections and (ii) layer aperiodicity, which destroys all two dimensional hk reflections. Given its topochemical relationship with the spinel structure, such an intermediate is a necessary precursor to spinel formation. Keywords.

  6. Thermal decomposition of 1-chloropropane behind the reflected ...

    Indian Academy of Sciences (India)

    effects such as stratospheric ozone depletion. Such problems can be reduced by minimizing the production ... as a method of destruction.1–4 Therefore, it is essential to understand the complete mechanism of .... such as real gas effects, boundary layer effects and exo or endothermicity of the chemical reactions. To esti-.

  7. Thermal decomposition of potassium bis-oxalatodiaqua- indate(III ...

    Indian Academy of Sciences (India)

    Unknown

    One of the authors (Tesfahun Kebede) thanks the Ethiopian Embassy, New Delhi for financial assistance. References. 1. Moeller J I 1940 J. Am. Chem. Soc. 62 2444. 2. Deichman E N 1959 Russ. J. Inorg. Chem. 4 11,1207. 3. Stary J 1963 Anal. Chim. Acta. 28 132. 4. Pingarron Carrazon J M, Gallego Andrew R and ...

  8. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    Author Affiliations. A Rasooli1 M A Boutorabi2 M Divandari2 A Azarniya1. Department of Materials Engineering, Faculty of Materials Engineering, University of Tabriz, P.O. Box 5166616471, Tabriz, Iran; School of Metallurgy and Materials Engineering, Iran University of Science and Technology, P.O. Box 16844, Tehran, Iran ...

  9. Thermal decomposition of dilute aqueous formic acid solutions

    DEFF Research Database (Denmark)

    Bjerre, A.B.; Sørensen, E.

    1992-01-01

    The aqueous-phase oxidation of formic acid and formate has been studied in a batch autoclave reactor at 260-degrees-C and 2 MPa of O2. The formate is converted to bicarbonate whereas formic acid, besides oxidation, decomposes by at least two different routes, namely a dehydration or a decarboxyla...

  10. Structure, optical and thermal decomposition characters of LDPE ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Methyl methacrylate (MMA) monomer was grafted onto low density polyethylene by the direct method of radiation grafting. The effect of cohesive energy density of different organic solvents on the degree of grafting was investigated. It was found that the extent of grafting depends largely on the kind of solvent, in.

  11. Thermal Decomposition of RP-2 with Stabilizing Additives

    Science.gov (United States)

    2010-04-01

    sealed on one end with a 316L stainless steel plug welded by a clean tungsten-inert-gas ( TIG ) process. The other end of each cell was connected to a...valve with a 3.5 cm length of narrow-diameter 316 stainless steel tubing that was TIG - welded to the larger diameter tube. The valves were appropriate

  12. Thermal decomposition of Co–Al layered double hydroxide ...

    Indian Academy of Sciences (India)

    This phase is characterized by a single strong basal reflection in its powder diffraction pattern. All other reflections are extinguished on account of. turbostratic disorder which destroys all ℎ reflections and; layer aperiodicity, which destroys all two dimensional ℎ reflections. Given its topochemical relationship with the ...

  13. A convenient thermal decomposition-co-reduction synthesis of ...

    Indian Academy of Sciences (India)

    Unknown

    Department of Chemistry, Wenzhou University, Wenzhou, Zhejiang 325035, P.R. China. †Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China,. Hefei, Anhui 230026, P.R. China ... The obtained products from the quartz tube were washed several times with 0⋅1 M ...

  14. Calcium-Amidoborane-Ammine Complexes : Thermal Decomposition of Model Systems

    NARCIS (Netherlands)

    Harder, Sjoerd; Spielmann, Jan; Tobey, Briac

    Hydrocarbon-soluble model systems for the calcium-amidoborane-ammine complex Ca(NH2BH3)2.(NH3)2 were prepared and structurally characterized. The following complexes were obtained by the reaction of RNH2BH3 (R=H, Me, iPr, DIPP; DIPP=2,6-diisopropylphenyl) with Ca(DIPP-nacnac)(NH2).(NH3)2

  15. Corrosion reliability of electronics: the influence of solder temperature on the decomposition of flux activators

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Conseil, Helene; Jellesen, Morten Stendahl

    2014-01-01

    This manuscript gives a brief overview on the studies of thermal decomposition of solder flux systems commonly used in the electronic industry. Changes in chemical composition and structural changes of the flux components have been investigated as a function of temperature. Six weak organic acids...

  16. Decomposition of soil organic matter from boreal black spruce forest: environmental and chemical controls

    Science.gov (United States)

    Kimberly P. Wickland; Jason C. Neff

    2007-01-01

    Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how...

  17. Decomposition of Diethylstilboestrol in Soil

    DEFF Research Database (Denmark)

    Gregers-Hansen, Birte

    1964-01-01

    The rate of decomposition of DES-monoethyl-1-C14 in soil was followed by measurement of C14O2 released. From 1.6 to 16% of the added C14 was recovered as C14O2 during 3 months. After six months as much as 12 to 28 per cent was released as C14O2.Determination of C14 in the soil samples after...... not inhibit the CO2 production from the soil.Experiments with γ-sterilized soil indicated that enzymes present in the soil are able to attack DES....

  18. Azimuthal decomposition with digital holograms

    CSIR Research Space (South Africa)

    Litvin, IA

    2012-05-01

    Full Text Available stream_source_info Litvin_2012.pdf.txt stream_content_type text/plain stream_size 26000 Content-Encoding ISO-8859-1 stream_name Litvin_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Azimuthal decomposition... outside the annular ring and 1 inside the ring was programmed using complex amplitude modulation for amplitude only effects on a phase-only device. The hologram takes the form of a high frequency grating that oscillates between phase values of 0...

  19. Kinetic analysis for non-isothermal decomposition of un-irradiated and gamma-irradiated anhydrous cadmium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Culas, S.; Samuel, J. [Mar Ivanios College, Kerala (India). Dept. of Chemistry

    2014-04-01

    The thermal decomposition of untreated and γ-irradiated samples of anhydrous cadmium nitrate was performed under non-isothermal conditions at different heating rates (5, 10, 15 and 20 C min{sup -1}). The results showed that the decomposition proceeds in one major step with the formation of cadmium oxide as solid residue. The data were analysed by using both isoconversional and non-isoconversional methods. The activation energy was calculated by various model-free isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with phase boundary reaction with spherical symmetry (R3 mechanism) for both untreated and irradiated salts at all heating rates. (orig.)

  20. Oxidative synthesis of a novel polyphenol having pendant Schiff base group: Synthesis, characterization, non-isothermal decomposition kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Dilek, Deniz [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Dogan, Fatih, E-mail: fatihdogan@comu.edu.tr [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Bilici, Ali, E-mail: alibilici66@hotmail.com [Control Laboratory of Agricultural and Forestry Ministry, 34153 Istanbul (Turkey); Kaya, Ismet [Department of Chemistry, Faculty of Science and Arts, Canakkale Onsekiz Mart University, Canakkale (Turkey)

    2011-05-10

    Research highlights: {yields} In this study, the synthesis and thermal characterization of a new functional polyphenol are reported. {yields} Non-isothermal methods were used to evaluate the thermal decomposition kinetics of resulting polymer. {yields} Thermal decomposition of polymer follows a diffusion type kinetic model. {yields} It is noted that this kinetic model is quite rare in polymer degradation studies. - Abstract: In here, the facile synthesis and thermal characterization of a novel polyphenol containing Schiff base pendant group, poly(4-{l_brace}[(4-hydroxyphenyl)imino]methyl{r_brace}benzene-1,2,3-triol) [PHPIMB], are reported. UV-vis, FT-IR, {sup 1}H NMR, {sup 13}C NMR, GPC, TG/DTG-DTA, CV (cyclic voltammetry) and solid state conductivity measurements were utilized to characterize the obtained monomer and polymer. The spectral analyses results showed that PHPIMB was composed of polyphenol main chains containing Schiff base pendant side groups. Thermal properties of the polymer were investigated by thermogravimetric analyses under a nitrogen atmosphere. Five methods were used to study the thermal decomposition of PHPIMB at different heating rate and the results obtained by using all the kinetic methods were compared with each other. The thermal decomposition of PHPIMB was found to be a simple process composed of three stages. These investigated methods were those of Flynn-Wall-Ozawa (FWO), Tang, Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods.

  1. Catalytic decomposition of nitrous oxide monopropellant for hybrid motor ignition

    Science.gov (United States)

    Wilson, Matthew

    Nitrous oxide (N2O) is an inexpensive and readily available non-toxic rocket motor oxidizer. It is the most commonly used oxidizer for hybrid bipropellant rocket systems, and several bipropellant liquid rocket designs have also used nitrous oxide. In liquid form, N2O is highly stable, but in vapor form it has the potential to decompose exothermically, releasing up to 1865 Joules per gram of vapor as it dissociates into nitrogen and oxygen. Consequently, it has long been considered as a potential "green" replacement for existing highly toxic and dangerous monopropellants. This project investigates the feasibility of using the nitrous oxide decomposition reaction as a monopropellant energy source for igniting liquid bipropellant and hybrid rockets that already use nitrous oxide as the primary oxidizer. Because nitrous oxide is such a stable propellant, the energy barrier to dissociation is quite high; normal thermal decomposition of the vapor phase does not occur until temperatures are above 800 C. The use of a ruthenium catalyst decreases the activation energy for this reaction to allow rapid decomposition below 400 C. This research investigates the design for a prototype device that channels the energy of dissociation to ignite a laboratory scale hybrid rocket motor.

  2. Parallel QR Decomposition for Electromagnetic Scattering Problems

    National Research Council Canada - National Science Library

    Boleng, Jeff

    1997-01-01

    This report introduces a new parallel QR decomposition algorithm. Test results are presented for several problem sizes, numbers of processors, and data from the electromagnetic scattering problem domain...

  3. Highly Scalable Matching Pursuit Signal Decomposition Algorithm

    Data.gov (United States)

    National Aeronautics and Space Administration — In this research, we propose a variant of the classical Matching Pursuit Decomposition (MPD) algorithm with significantly improved scalability and computational...

  4. Symmetric Decomposition of Asymmetric Games.

    Science.gov (United States)

    Tuyls, Karl; Pérolat, Julien; Lanctot, Marc; Ostrovski, Georg; Savani, Rahul; Leibo, Joel Z; Ord, Toby; Graepel, Thore; Legg, Shane

    2018-01-17

    We introduce new theoretical insights into two-population asymmetric games allowing for an elegant symmetric decomposition into two single population symmetric games. Specifically, we show how an asymmetric bimatrix game (A,B) can be decomposed into its symmetric counterparts by envisioning and investigating the payoff tables (A and B) that constitute the asymmetric game, as two independent, single population, symmetric games. We reveal several surprising formal relationships between an asymmetric two-population game and its symmetric single population counterparts, which facilitate a convenient analysis of the original asymmetric game due to the dimensionality reduction of the decomposition. The main finding reveals that if (x,y) is a Nash equilibrium of an asymmetric game (A,B), this implies that y is a Nash equilibrium of the symmetric counterpart game determined by payoff table A, and x is a Nash equilibrium of the symmetric counterpart game determined by payoff table B. Also the reverse holds and combinations of Nash equilibria of the counterpart games form Nash equilibria of the asymmetric game. We illustrate how these formal relationships aid in identifying and analysing the Nash structure of asymmetric games, by examining the evolutionary dynamics of the simpler counterpart games in several canonical examples.

  5. Decomposition methods in turbulence research

    Science.gov (United States)

    Uruba, Václav

    2012-04-01

    Nowadays we have the dynamical velocity vector field of turbulent flow at our disposal coming thanks advances of either mathematical simulation (DNS) or of experiment (time-resolved PIV). Unfortunately there is no standard method for analysis of such data describing complicated extended dynamical systems, which is characterized by excessive number of degrees of freedom. An overview of candidate methods convenient to spatiotemporal analysis for such systems is to be presented. Special attention will be paid to energetic methods including Proper Orthogonal Decomposition (POD) in regular and snapshot variants as well as the Bi-Orthogonal Decomposition (BOD) for joint space-time analysis. Then, stability analysis using Principal Oscillation Patterns (POPs) will be introduced. Finally, the Independent Component Analysis (ICA) method will be proposed for detection of coherent structures in turbulent flow-field defined by time-dependent velocity vector field. Principle and some practical aspects of the methods are to be shown. Special attention is to be paid to physical interpretation of outputs of the methods listed above.

  6. Decomposition methods in turbulence research

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2012-04-01

    Full Text Available Nowadays we have the dynamical velocity vector field of turbulent flow at our disposal coming thanks advances of either mathematical simulation (DNS or of experiment (time-resolved PIV. Unfortunately there is no standard method for analysis of such data describing complicated extended dynamical systems, which is characterized by excessive number of degrees of freedom. An overview of candidate methods convenient to spatiotemporal analysis for such systems is to be presented. Special attention will be paid to energetic methods including Proper Orthogonal Decomposition (POD in regular and snapshot variants as well as the Bi-Orthogonal Decomposition (BOD for joint space-time analysis. Then, stability analysis using Principal Oscillation Patterns (POPs will be introduced. Finally, the Independent Component Analysis (ICA method will be proposed for detection of coherent structures in turbulent flow-field defined by time-dependent velocity vector field. Principle and some practical aspects of the methods are to be shown. Special attention is to be paid to physical interpretation of outputs of the methods listed above.

  7. Avaliação da resistência ao desgaste de aluminas nanométricas produzidas a partir da decomposição térmica de acetato de alumínio liofilizado Evaluation of wear resistance of nanometric aluminas produced by thermal decomposition of lyophilized aluminum acetate

    Directory of Open Access Journals (Sweden)

    E. Fagury Neto

    2007-12-01

    Full Text Available Ensaios de resistência ao desgaste, na modalidade pino-contra-disco com pares deslizantes, foram realizados em pinos confeccionados a partir de pós de alumina proveniente do processo de decomposição térmica de acetato de alumínio liofilizado. Pós de alumina referentes às fases alfa-Al2O3 e gama-Al2O3, com e sem aditivos de sinterização (MgO e La2O3, foram usados para confeccionar pinos de desgaste. Pinos feitos também a partir de alumina comercial (A1000 SG foram analisados e os resultados foram comparados. Os ensaios foram feitos de acordo com norma ASTM e mostraram que os pinos confeccionados a partir de alfa-Al2O3 têm elevada resistência ao desgaste, comprovada pelos ensaios de perda de massa e microscopia eletrônica. Os pinos de gama-Al2O3 tiveram desempenho intermediário e os pinos de A1000 SG mostraram resultados menos expressivos.Wear resistance tests, using the pin-on-disk test method with sliding pairs, were carried out on pins produced from alumina powders prepared by thermal decomposition of lyophilized aluminum acetate. Alumina powders of alpha-Al2O3 and gamma-Al2O3 phases, with and without sintering additives (MgO and La2O3, were used to produce wear pins. In addition, pins made of commercial alumina (A1000 SG were tested and the results compared. The tests, carried out according to the ASTM standard, indicated that the pins made with alpha-Al2O3 powder showed high wear resistance, a finding corroborated by mass loss tests and scanning electron microscopy. The gamma-Al2O3 pins showed an intermediary performance while the A1000 SG pins showed less interesting results.

  8. Influence of Cu(NO32 initiation additive in two-stage mode conditions of coal pyrolytic decomposition

    Directory of Open Access Journals (Sweden)

    Larionov Kirill

    2017-01-01

    Full Text Available Two-stage process (pyrolysis and oxidation of brown coal sample with Cu(NO32 additive pyrolytic decomposition was studied. Additive was introduced by using capillary wetness impregnation method with 5% mass concentration. Sample reactivity was studied by thermogravimetric analysis with staged gaseous medium supply (argon and air at heating rate 10 °C/min and intermediate isothermal soaking. The initiative additive introduction was found to significantly reduce volatile release temperature and accelerate thermal decomposition of sample. Mass-spectral analysis results reveal that significant difference in process characteristics is connected to volatile matter release stage which is initiated by nitrous oxide produced during copper nitrate decomposition.

  9. Influence of calcium carbonate on the decomposition of asbestos contained in end-of-life products

    Energy Technology Data Exchange (ETDEWEB)

    Belardi, G. [Environmental Geology and GeoEngineering Institute (CNR), Area della ricerca RM1, via Salaria km 29,300, 00016 Monterotondo (Rome) (Italy); Piga, L., E-mail: luigi.piga@uniroma1.it [Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, via Eudossiana 84, 00184 Rome (Italy)

    2013-12-10

    Highlights: • We characterized end-of-life asbestos-containing materials. • In the range 620–680 °C, calcite and quartz affect decomposition of asbestos. • Hypothesized decomposition reactions match with solid phases revealed by XRD analysis. • TGA of the content of chrysotile gives good results both in air and in nitrogen. - Abstract: Three bearing-asbestos wastes, friction material, vinyl-asbestos (linoleum) and cement-asbestos mainly containing chrysotile were characterized. Powder X-ray diffraction (XRDP), scanning electron microscopy (SEM) with microanalysis observations and thermal analysis (TGA/DTA) were carried out on the materials as received and after heating at 1100 °C in order to observe their structural changes and thermal behaviours. A quantitative determination of chrysotile in the friction material was also carried out. To study the influence of CaCO{sub 3} on the decomposition of asbestos, the three techniques were also applied on the linoleum and cement-asbestos at room temperature and at 1100 °C after leaching of the materials with 1:3 HCl to remove the carbonates present in the wastes. The results show that the presence of CaCO{sub 3} prevents the asbestos to decompose according to the known decomposition reactions and leads to the formation of calcium-silicate compounds. When CaCO{sub 3} is removed by washing with HCl, decomposition of asbestos proceeds according to the expected reactions.

  10. Thermal shock resistance ceramic insulator

    Science.gov (United States)

    Morgan, Chester S.; Johnson, William R.

    1980-01-01

    Thermal shock resistant cermet insulators containing 0.1-20 volume % metal present as a dispersed phase. The insulators are prepared by a process comprising the steps of (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, said metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide a cermet insulator having 0.1-20 volume % metal present as a dispersed phase.

  11. Decomposition kinetics of plutonium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, J.M.; Stakebake, J.L.

    1979-01-01

    Kinetic data for decomposition of PuH/sub 1/ /sub 95/ provides insight into a possible mechanism for the hydriding and dehydriding reactions of plutonium. The fact that the rate of the hydriding reaction, K/sub H/, is proportional to P/sup 1/2/ and the rate of the dehydriding process, K/sub D/, is inversely proportional to P/sup 1/2/ suggests that the forward and reverse reactions proceed by opposite paths of the same mechanism. The P/sup 1/2/ dependence of hydrogen solubility in metals is characteristic of the dissociative absorption of hydrogen; i.e., the reactive species is atomic hydrogen. It is reasonable to assume that the rates of the forward and reverse reactions are controlled by the surface concentration of atomic hydrogen, (H/sub s/), that K/sub H/ = c'(H/sub s/), and that K/sub D/ = c/(H/sub s/), where c' and c are proportionality constants. For this surface model, the pressure dependence of K/sub D/ is related to (H/sub s/) by the reaction (H/sub s/) reversible 1/2H/sub 2/(g) and by its equilibrium constant K/sub e/ = (H/sub 2/)/sup 1/2//(H/sub s/). In the pressure range of ideal gas behavior, (H/sub s/) = K/sub e//sup -1/(RT)/sup -1/2/ and the decomposition rate is given by K/sub D/ = cK/sub e/(RT)/sup -1/2/P/sup 1/2/. For an analogous treatment of the hydriding process with this model, it can be readily shown that K/sub H/ = c'K/sub e//sup -1/(RT)/sup -1/2/P/sup 1/2/. The inverse pressure dependence and direct temperature dependence of the decomposition rate are correctly predicted by this mechanism which is most consistent with the observed behavior of the Pu--H system.

  12. Application Of Adomian's Decomposition Method In Solving ...

    African Journals Online (AJOL)

    It is shown in literature that Adomian's decomposition method gives better results than any other computational techniques. We use this method to tackle simple heat equation and compare the result with the closed form solution of the giving problem. Keywords: Adomian decomposition method; accuracy; nonlinear equation ...

  13. Modular polynomial arithmetic in partial fraction decomposition

    Science.gov (United States)

    Abdali, S. K.; Caviness, B. F.; Pridor, A.

    1977-01-01

    Algorithms for general partial fraction decomposition are obtained by using modular polynomial arithmetic. An algorithm is presented to compute inverses modulo a power of a polynomial in terms of inverses modulo that polynomial. This algorithm is used to make an improvement in the Kung-Tong partial fraction decomposition algorithm.

  14. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    Unknown

    A-rich grain boundary layer followed by a B-rich layer; the grain interior exhibits a spinodally decomposed microstructure, evolving slowly. Further, grain growth is suppressed completely during the decomposition process. Keywords. Spinodal decomposition; grain boundary effects; phase field models. 1. Introduction.

  15. An Introduction to Clique Minimal Separator Decomposition

    Directory of Open Access Journals (Sweden)

    Anne Berry

    2010-05-01

    Full Text Available This paper is a review which presents and explains the decomposition of graphs by clique minimal separators. The pace is leisurely, we give many examples and figures. Easy algorithms are provided to implement this decomposition. The historical and theoretical background is given, as well as sketches of proofs of the structural results involved.

  16. Some Aspects of Thermochemical Decomposition of Peat

    Directory of Open Access Journals (Sweden)

    Y. A. Losiuk

    2008-01-01

    Full Text Available The paper considers peculiar features of thermochemical decomposition of peat as a result of quick pyrolysis. Evaluation of energy and economic expediency of the preliminary peat decomposition process for obtaining liquid and gaseous products has been made in the paper. The paper reveals prospects pertaining to application of the given technology while generating electric power and heat.

  17. Moisture controls decomposition rate in thawing tundra

    Science.gov (United States)

    C.E. Hicks-Pries; E.A.G. Schuur; S.M. Natali; J.G. Vogel

    2013-01-01

    Permafrost thaw can affect decomposition rates by changing environmental conditions and litter quality. As permafrost thaws, soils warm and thermokarst (ground subsidence) features form, causing some areas to become wetter while other areas become drier. We used a common substrate to measure how permafrost thaw affects decomposition rates in the surface soil in a...

  18. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    We have used a phase field model to study spinodal decomposition in polycrystalline materials in which the grain size is of the same order of magnitude as the characteristic decomposition wavelength ( λ S D ). In the spirit of phase field models, each grain () in our model has an order parameter ( η i ) associated with it; ...

  19. Climate history shapes contemporary leaf litter decomposition

    Science.gov (United States)

    Michael S. Strickland; Ashley D. Keiser; Mark A. Bradford

    2015-01-01

    Litter decomposition is mediated by multiple variables, of which climate is expected to be a dominant factor at global scales. However, like other organisms, traits of decomposers and their communities are shaped not just by the contemporary climate but also their climate history. Whether or not this affects decomposition rates is underexplored. Here we source...

  20. Multilinear operators for higher-order decompositions.

    Energy Technology Data Exchange (ETDEWEB)

    Kolda, Tamara Gibson

    2006-04-01

    We propose two new multilinear operators for expressing the matrix compositions that are needed in the Tucker and PARAFAC (CANDECOMP) decompositions. The first operator, which we call the Tucker operator, is shorthand for performing an n-mode matrix multiplication for every mode of a given tensor and can be employed to concisely express the Tucker decomposition. The second operator, which we call the Kruskal operator, is shorthand for the sum of the outer-products of the columns of N matrices and allows a divorce from a matricized representation and a very concise expression of the PARAFAC decomposition. We explore the properties of the Tucker and Kruskal operators independently of the related decompositions. Additionally, we provide a review of the matrix and tensor operations that are frequently used in the context of tensor decompositions.

  1. Thermochemistry and kinetics of graphite oxide exothermic decomposition for safety in large-scale storage and processing.

    Science.gov (United States)

    Qiu, Yang; Collin, Felten; Hurt, Robert H; Külaots, Indrek

    2016-01-01

    The success of graphene technologies will require the development of safe and cost-effective nano-manufacturing methods. Special safety issues arise for manufacturing routes based on graphite oxide (GO) as an intermediate due to its energetic behavior. This article presents a detailed thermochemical and kinetic study of GO exothermic decomposition designed to identify the conditions and material compositions that avoid explosive events during storage and processing at large scale. It is shown that GO becomes more reactive for thermal decomposition when it is pretreated with OH(-) in suspension and the effect is reversible by back-titration to low pH. This OH(-) effect can lower the decomposition reaction exotherm onset temperature by up to 50 degrees of Celsius, causing overlap with common drying operations (100-120°C) and possible self-heating and thermal runaway during processing. Spectroscopic and modeling evidence suggest epoxide groups are primarily responsible for the energetic behavior, and epoxy ring opening/closing reactions are offered as an explanation for the reversible effects of pH on decomposition kinetics and enthalpies. A quantitative kinetic model is developed for GO thermal decomposition and used in a series of case studies to predict the storage conditions under which spontaneous self-heating, thermal runaway, and explosions can be avoided.

  2. Surface-directed spinodal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Puri, Sanjay [School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067 (India)

    2005-01-26

    We review analytical and numerical results for surface-directed spinodal decomposition (SDSD), namely, the interplay of wetting kinetics and phase separation in a binary (AB) mixture in contact with a surface S which prefers one of the components (say, A). Depending on the relative strengths of the A-B, A-S and B-S interactions, the surface is either partially wetted or completely wetted by A in equilibrium. We discuss the theoretical framework for modelling SDSD, and review results obtained from both microscopic and coarse-grained models. We clarify the differences between diffusion-driven SDSD in solids, and SDSD in fluids, where velocity fields play an important role. Furthermore, we discuss the dependence of wetting-layer kinetics on the composition of the mixture. Some results are also presented for phase separation in a confined geometry, e.g., thin films. Finally, we discuss the problem of surface-enrichment kinetics, namely, the kinetics of enrichment of an attracting surface when the bulk mixture is stable. These nonequilibrium processes have important applications in the preparation of nanomaterials and multi-layered structures. (topical review)

  3. Geometric decompositions of collective motion

    Science.gov (United States)

    Mischiati, Matteo; Krishnaprasad, P. S.

    2017-04-01

    Collective motion in nature is a captivating phenomenon. Revealing the underlying mechanisms, which are of biological and theoretical interest, will require empirical data, modelling and analysis techniques. Here, we contribute a geometric viewpoint, yielding a novel method of analysing movement. Snapshots of collective motion are portrayed as tangent vectors on configuration space, with length determined by the total kinetic energy. Using the geometry of fibre bundles and connections, this portrait is split into orthogonal components each tangential to a lower dimensional manifold derived from configuration space. The resulting decomposition, when interleaved with classical shape space construction, is categorized into a family of kinematic modes-including rigid translations, rigid rotations, inertia tensor transformations, expansions and compressions. Snapshots of empirical data from natural collectives can be allocated to these modes and weighted by fractions of total kinetic energy. Such quantitative measures can provide insight into the variation of the driving goals of a collective, as illustrated by applying these methods to a publicly available dataset of pigeon flocking. The geometric framework may also be profitably employed in the control of artificial systems of interacting agents such as robots.

  4. Further remarks on convergence of decomposition method.

    Science.gov (United States)

    Cherruault, Y; Adomian, G; Abbaoui, K; Rach, R

    1995-01-01

    The decomposition method solves a wide class of nonlinear functional equations. This method uses a series solution with rapid convergence. This paper is intended as a useful review and clarification of related issues.

  5. A Decomposition Theorem for Finite Automata.

    Science.gov (United States)

    Santa Coloma, Teresa L.; Tucci, Ralph P.

    1990-01-01

    Described is automata theory which is a branch of theoretical computer science. A decomposition theorem is presented that is easier than the Krohn-Rhodes theorem. Included are the definitions, the theorem, and a proof. (KR)

  6. Decomposition Analysis of Forest Ecosystem Services Values

    National Research Council Canada - National Science Library

    Hidemichi Fujii; Masayuki Sato; Shunsuke Managi

    2017-01-01

    .... We applied two approaches: a contingent valuation method for estimating the forest ecosystem service value per area and a decomposition analysis for identifying the main driving factors of changes in the value of forest ecosystem services...

  7. The decomposition of estuarine macrophytes under different ...

    African Journals Online (AJOL)

    2013-04-29

    Apr 29, 2013 ... knowledge of the decomposition rates of algal species in order to validate their role in the ... sure in the Great Brak Estuary, numerous filamentous green algae ... structure and functioning of the estuary and as such need to.

  8. Spectroscopic, thermal and biological studies of coordination ...

    Indian Academy of Sciences (India)

    Administrator

    (Cl)(H2O)3]⋅xH2O (M = Cr(III) and Y(III), x = 5 and 6, respectively) were obtained and characterized by physicochemical and spectroscopic methods. The IR spectra of the complexes suggest that the sulfasalazine behaves as a monoanionic bidentate ligand. The thermal decomposition of the complexes as well as ...

  9. Effect of heating method on NOx decomposition on H3PW12O40•6H2O

    Directory of Open Access Journals (Sweden)

    R. Wang

    2013-05-01

    Full Text Available The thermal decomposition of nitrogen oxides (NOx on phosphotungstic acid (H3PW12O40·6H2O or HPW by two different heating methods is compared. Infra-red (IR and X-ray diffraction (XRD measurements are conducted to investigate the decomposition mechanism. Both heating methods, i.e. heating from 30 °C to 450 °C at a rate of 150 °C/min (“rapid heating” and heating at a constant temperature of 450 °C (“constant-temperature heating” lead to an actual, considerably high heating rate. Compared with rapid heating, however, constant-temperature heating results in enhanced N2 conversion (21.8%. Furthermore, the catalyst can be reused after decomposition at constant-temperature heating, while its performance quickly degrades after decomposition via rapid heating.

  10. Sponge-like silver obtained by decomposition of silver nitrate hexamethylenetetramine complex

    Energy Technology Data Exchange (ETDEWEB)

    Afanasiev, Pavel, E-mail: pavel.afanasiev@ircelyon.univ-lyon.fr

    2016-07-15

    Silver nitrate hexamethylenetetramine [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] coordination compound has been prepared via aqueous route and characterized by chemical analysis, XRD and electron microscopy. Decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] under hydrogen and under inert has been studied by thermal analysis and mass spectrometry. Thermal decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] proceeds in the range 200–250 °C as a self-propagating rapid redox process accompanied with the release of multiple gases. The decomposition leads to formation of sponge-like silver having hierarchical open pore system with pore size spanning from 10 µm to 10 nm. The as-obtained silver sponges exhibited favorable activity toward H{sub 2}O{sub 2} electrochemical reduction, making them potentially interesting as non-enzyme hydrogen peroxide sensors. - Graphical abstract: Thermal decomposition of silver nitrate hexamethylenetetramine coordination compound [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] leads to sponge like silver that possesses open porous structure and demonstrates interesting properties as an electrochemical hydrogen peroxide sensor. Display Omitted - Highlights: • [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] orthorhombic phase prepared and characterized. • Decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] leads to metallic silver sponge with opened porosity. • Ag sponge showed promising properties as a material for hydrogen peroxide sensors.

  11. Multipartite graph decomposition: cycles and closed trails

    Directory of Open Access Journals (Sweden)

    Elizabeth J. Billington

    2004-11-01

    Full Text Available This paper surveys results on cycle decompositions of complete multipartite graphs (where the parts are not all of size 1, so the graph is not K_n , in the case that the cycle lengths are “small”. Cycles up to length n are considered, when the complete multipartite graph has n parts, but not hamilton cycles. Properties which the decompositions may have, such as being gregarious, are also mentioned.

  12. Microbiological decomposition of bagasse after radiation pasteurization

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hitoshi; Ishigaki, Isao

    1987-11-01

    Microbiological decomposition of bagasse was studied for upgrading to animal feeds after radiation pasteurization. Solid-state culture media of bagasse were prepared with addition of some amount of inorganic salts for nitrogen source, and after irradiation, fungi were infected for cultivation. In this study, many kind of cellulosic fungi such as Pleurotus ostreatus, P. flavellatus, Verticillium sp., Coprinus cinereus, Lentinus edodes, Aspergillus niger, Trichoderma koningi, T. viride were used for comparison of decomposition of crude fibers. In alkali nontreated bagasse, P. ostreatus, P. flavellatus, C. cinereus and Verticillium sp. could decompose crude fibers from 25 to 34 % after one month of cultivation, whereas other fungi such as A. niger, T. koningi, T. viride, L. edodes decomposed below 10 %. On the contrary, alkali treatment enhanced the decomposition of crude fiber by A. niger, T. koningi and T. viride to be 29 to 47 % as well as Pleurotus species or C. cinereus. Other species of mushrooms such as L. edodes had a little ability of decomposition even after alkali treatment. Radiation treatment with 10 kGy could not enhance the decomposition of bagasse compared with steam treatment, whereas higher doses of radiation treatment enhanced a little of decomposition of crude fibers by microorganisms.

  13. Pyrolysis of methyl tert-butyl ether (MTBE). 2. Theoretical study of decomposition pathways.

    Science.gov (United States)

    Zhang, Taichang; Zhang, Lidong; Wang, Jing; Yuan, Tao; Hong, Xin; Qi, Fei

    2008-10-23

    The thermal decomposition pathways of MTBE have been investigated using the G3B3 method. On the basis of the experimental observation and theoretical calculation, the pyrolysis channels are provided, especially for primary pyrolysis reactions. The primary decomposition pathways include formation of methanol and isobutene, CH4 elimination, H2 elimination and C-H, C-C, C-O bond cleavage reactions. Among them, the formation channel of methanol and isobutene is the lowest energy pathway, which is in accordance with experimental observation. Furthermore, the secondary pyrolysis pathways have been calculated as well, including decomposition of tert-butyl radical, isobutene, methanol and acetone. The radicals play an important role in the formation of pyrolysis products, for example, tert-butyl radical and allyl radical are major precursors for the formation of allene and propyne. Although some isomers (isobutene and 1-butene, allene and propyne, acetone and propanal) are identified in our experiment, these isomerization reaction pathways occur merely at the high temperature due to their high activation energies. The theoretical calculation can explain the experimental results reported in part 1 and shed further light on the thermal decomposition pathways.

  14. Study of thermal behavior of phytic acid

    Directory of Open Access Journals (Sweden)

    André Luis Máximo Daneluti

    2013-06-01

    Full Text Available Phytic acid is a natural compound widely used as depigmenting agent in galenic cosmetic emulsions. However, we have observed experimentally that phytic acid, when heated to 150 ºC for around one hour, shows evidence of thermal decomposition. Few studies investigating this substance alone with regard to its stability are available in the literature. This fact prompted the present study to characterize this species and its thermal behavior using thermal analysis (TG/DTG and DSC and to associate the results of these techniques with those obtained by elemental analysis (EA and absorption spectroscopy in the infrared region. The TG/DTG and DSC curves allowed evaluation of the thermal behavior of the sample of phytic acid and enabled use of the non-isothermal thermogravimetric method to study the kinetics of the three main mass-loss events: dehydration I, dehydration II and thermal decomposition. The combination of infrared absorption spectroscopy and elemental analysis techniques allowed evaluation of the intermediate products of the thermal decomposition of phytic acid. The infrared spectra of samples taken during the heating process revealed a reduction in the intensity of the absorption band related to O-H stretching as a result of the dehydration process. Furthermore, elemental analysis results showed an increase in the carbon content and a decrease in the hydrogen content at temperatures of 95, 150, 263 and 380 °C. Visually, darkening of the material was observed at 150 °C, indicating that the thermal decomposition of the material started at this temperature. At a temperature of 380 °C, thermal decomposition progressed, leading to a decrease in carbon and hydrogen. The results of thermogravimetry coupled with those of elemental analysis allow us to conclude that there was agreement between the percentages of phytic acid found in aqueous solution. The kinetic study by the non-isothermal thermogravimetric method showed that the dehydration

  15. Vibration fatigue using modal decomposition

    Science.gov (United States)

    Mršnik, Matjaž; Slavič, Janko; Boltežar, Miha

    2018-01-01

    Vibration-fatigue analysis deals with the material fatigue of flexible structures operating close to natural frequencies. Based on the uniaxial stress response, calculated in the frequency domain, the high-cycle fatigue model using the S-N curve material data and the Palmgren-Miner hypothesis of damage accumulation is applied. The multiaxial criterion is used to obtain the equivalent uniaxial stress response followed by the spectral moment approach to the cycle-amplitude probability density estimation. The vibration-fatigue analysis relates the fatigue analysis in the frequency domain to the structural dynamics. However, once the stress response within a node is obtained, the physical model of the structure dictating that response is discarded and does not propagate through the fatigue-analysis procedure. The structural model can be used to evaluate how specific dynamic properties (e.g., damping, modal shapes) affect the damage intensity. A new approach based on modal decomposition is presented in this research that directly links the fatigue-damage intensity with the dynamic properties of the system. It thus offers a valuable insight into how different modes of vibration contribute to the total damage to the material. A numerical study was performed showing good agreement between results obtained using the newly presented approach with those obtained using the classical method, especially with regards to the distribution of damage intensity and critical point location. The presented approach also offers orders of magnitude faster calculation in comparison with the conventional procedure. Furthermore, it can be applied in a straightforward way to strain experimental modal analysis results, taking advantage of experimentally measured strains.

  16. Aridity and decomposition processes in complex landscapes

    Science.gov (United States)

    Ossola, Alessandro; Nyman, Petter

    2015-04-01

    Decomposition of organic matter is a key biogeochemical process contributing to nutrient cycles, carbon fluxes and soil development. The activity of decomposers depends on microclimate, with temperature and rainfall being major drivers. In complex terrain the fine-scale variation in microclimate (and hence water availability) as a result of slope orientation is caused by differences in incoming radiation and surface temperature. Aridity, measured as the long-term balance between net radiation and rainfall, is a metric that can be used to represent variations in water availability within the landscape. Since aridity metrics can be obtained at fine spatial scales, they could theoretically be used to investigate how decomposition processes vary across complex landscapes. In this study, four research sites were selected in tall open sclerophyll forest along a aridity gradient (Budyko dryness index ranging from 1.56 -2.22) where microclimate, litter moisture and soil moisture were monitored continuously for one year. Litter bags were packed to estimate decomposition rates (k) using leaves of a tree species not present in the study area (Eucalyptus globulus) in order to avoid home-field advantage effects. Litter mass loss was measured to assess the activity of macro-decomposers (6mm litter bag mesh size), meso-decomposers (1 mm mesh), microbes above-ground (0.2 mm mesh) and microbes below-ground (2 cm depth, 0.2 mm mesh). Four replicates for each set of bags were installed at each site and bags were collected at 1, 2, 4, 7 and 12 months since installation. We first tested whether differences in microclimate due to slope orientation have significant effects on decomposition processes. Then the dryness index was related to decomposition rates to evaluate if small-scale variation in decomposition can be predicted using readily available information on rainfall and radiation. Decomposition rates (k), calculated fitting single pool negative exponential models, generally

  17. High-temperature unimolecular decomposition of ethyl propionate

    KAUST Repository

    Giri, Binod

    2016-10-09

    This work reports rate coefficients of the thermal unimolecular decomposition reaction of ethyl propionate (EP) behind reflected shock waves over the temperature range of 976–1300 K and pressures of 825–1875 Torr. The reaction progress was monitored by detecting CH near 10.532 μm using CO gas laser absorption. In addition, G3//MP2/aug-cc-pVDZ and master equation calculations were performed to assess the pressure- and temperature-dependence of the reaction. Our calculations revealed that CH elimination occurs via a six-centered retro-ene transition state. Our measured rate data are close to the high-pressure limit and showed no discernable temperature fall off.

  18. Methane decomposition on Fe-Cu Raney-type catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, A.F.; Orfao, J.J.M.; Figueiredo, J.L. [Laboratorio de Catalise e Materiais, Laboratorio Associado LSRE/LCM, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)

    2009-10-15

    The decomposition of methane into hydrogen and carbon was studied on Fe-Cu catalysts of Raney-type. The activity of the catalysts was assessed by comparing the experimental conversions with the calculated equilibrium conversions for each set of experimental conditions. The stability of the catalysts was assessed by comparing the maximum conversions with the conversions at the end of 5-hour tests. The carbon deposits obtained consist mostly of carbon nanofibers. Good results were obtained when the Fe-Cu Raney-type systems were thermally treated in situ at 600 C, as a result of incipient alloy formation. These catalysts showed higher stability than the monometallic Raney-Fe catalysts. (author)

  19. Automated Decomposition of Model-based Learning Problems

    Science.gov (United States)

    Williams, Brian C.; Millar, Bill

    1996-01-01

    A new generation of sensor rich, massively distributed autonomous systems is being developed that has the potential for unprecedented performance, such as smart buildings, reconfigurable factories, adaptive traffic systems and remote earth ecosystem monitoring. To achieve high performance these massive systems will need to accurately model themselves and their environment from sensor information. Accomplishing this on a grand scale requires automating the art of large-scale modeling. This paper presents a formalization of [\\em decompositional model-based learning (DML)], a method developed by observing a modeler's expertise at decomposing large scale model estimation tasks. The method exploits a striking analogy between learning and consistency-based diagnosis. Moriarty, an implementation of DML, has been applied to thermal modeling of a smart building, demonstrating a significant improvement in learning rate.

  20. How nitric oxide affects the decomposition of supported nickel nitrate to arrive at highly dispersed catalysts

    NARCIS (Netherlands)

    Sietsma, J.R.A.; Friedrich, H.|info:eu-repo/dai/nl/304837350; Broersma, A.|info:eu-repo/dai/nl/311437532; Versluijs-Helder, M.|info:eu-repo/dai/nl/311472699; van Dillen, A.J.|info:eu-repo/dai/nl/111157625; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2008-01-01

    An explanation is put forward for the beneficial effect of thermal decomposition of supported Ni3(NO3)2(OH)4 in NO/He flow (0.1–1 vol%) that enables preparation of well-dispersed (3–5 nm particles) 24 wt% Ni-catalysts via impregnation and drying using aqueous [Ni(OH2)6](NO3)2 precursor solution.

  1. Decomposition of tetra-alkylammonium thiomolybdates characterised by thermoanalysis and mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Poisot, M. [Institut fuer Anorganische Chemie, University of Kiel, Olshausenstr. 40-60, 24118 Kiel (Germany); Bensch, W. [Institut fuer Anorganische Chemie, University of Kiel, Olshausenstr. 40-60, 24118 Kiel (Germany)]. E-mail: wbensch@ac.uni-kiel.de; Fuentes, S. [Centro de Ciencias de la Materia Condensada, Universidad Nacional Autonoma de, Mexico, Apdo. Postal 2681, Ensenada, Baja California, CP 22800 (Mexico); Alonso, G. [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes No. 120, Chihuahua, Chih., CP 31110 (Mexico)

    2006-05-01

    The decomposition pattern of tetraalkyl-tetrathiomolybdates with general formula (R{sub 4}N){sub 2}MoS{sub 4} (with R increasing from methyl to heptyl) was determined by means of differential thermal analysis (DTA), thermogravimetric analysis (TGA) and mass spectroscopy (MS) techniques. The complexity of thermal decomposition reactions increases with the size of the R{sub 4}N group. Prior to decomposition at least one phase transition seems to occur in all complexes. The onset of thermal reactions was also a function of the tetra-alkylammonium precursor. All compounds decompose without forming sulfur rich MoS{sub 2+x} intermediates. For R = methyl to pentyl precursors the MoS{sub 2} produced was nearly stoichiometric, however for R = hexyl and heptyl the S content was significantly reduced with a Mo:S ratio of about 1.5. The carbon and hydrogen residual contents in the product increased with the number of C atoms in R{sub 4}N; for N contamination no clear trend was obvious. SEM images show that the formation of macro-pores was also a function of the alkyl group in R{sub 4}N. The MoS{sub 2} materials obtained show a sponge-like morphology. Results of DSC experiments in combination with in situ X-ray diffraction also revealed the complex thermal behavior of (R{sub 4}N){sub 2}MoS{sub 4} materials; reversible and irreversible phase transitions and glass-like transformations were identified in the low temperature range (35-140 deg. C), before the onset of decomposition.

  2. Temperature sensitivity and enzymatic mechanisms of soil organic matter decomposition along an altitudinal gradient on Mount Kilimanjaro.

    Science.gov (United States)

    Blagodatskaya, Еvgenia; Blagodatsky, Sergey; Khomyakov, Nikita; Myachina, Olga; Kuzyakov, Yakov

    2016-02-29

    Short-term acceleration of soil organic matter decomposition by increasing temperature conflicts with the thermal adaptation observed in long-term studies. Here we used the altitudinal gradient on Mt. Kilimanjaro to demonstrate the mechanisms of thermal adaptation of extra- and intracellular enzymes that hydrolyze cellulose, chitin and phytate and oxidize monomers ((14)C-glucose) in warm- and cold-climate soils. We revealed that no response of decomposition rate to temperature occurs because of a cancelling effect consisting in an increase in half-saturation constants (Km), which counteracts the increase in maximal reaction rates (Vmax with temperature). We used the parameters of enzyme kinetics to predict thresholds of substrate concentration (Scrit) below which decomposition rates will be insensitive to global warming. Increasing values of Scrit, and hence stronger canceling effects with increasing altitude on Mt. Kilimanjaro, explained the thermal adaptation of polymer decomposition. The reduction of the temperature sensitivity of Vmax along the altitudinal gradient contributed to thermal adaptation of both polymer and monomer degradation. Extrapolating the altitudinal gradient to the large-scale latitudinal gradient, these results show that the soils of cold climates with stronger and more frequent temperature variation are less sensitive to global warming than soils adapted to high temperatures.

  3. Decomposition of hydroxylamine by hemoglobin.

    Science.gov (United States)

    Bazylinski, D A; Arkowitz, R A; Hollocher, T C

    1987-12-01

    The reaction between hydroxylamine (NH2OH) and human hemoglobin (Hb) at pH 6-8 and the reaction between NH2OH and methemoglobin (Hb+) chiefly at pH 7 were studied under anaerobic conditions at 25 degrees C. In presence of cyanide, which was used to trap Hb+, Hb was oxidized by NH2OH to methemoglobin cyanide with production of about 0.5 mol NH+4/mol of heme oxidized at pH 7. The conversion of Hb to Hb+ was first order in [Hb] (or nearly so) but the pseudo-first-order rate constant was not strictly proportional to [NH2OH]. Thus, the apparent second-order rate constant at pH 7 decreased from about 30 M-1 X s-1 to a limiting value of 11.3 M-1 X s-1 with increasing [NH2OH]. The rate of Hb oxidation was not much affected by cyanide, whereas there was no reaction between NH2OH and carbonmonoxyhemoglobin (HbCO). The pseudo-first-order rate constant for Hb oxidation at 500 microM NH2OH increased from about 0.008 s-1 at pH 6 to 0.02 s-1 at pH 8. The oxidation of Hb by NH2OH terminated prematurely at 75-90% completion at pH 7 and at 30-35% completion at pH 8. Data on the premature termination of reaction fit the titration curve for a group with pK = 7.5-7.7. NH2OH was decomposed by Hb+ to N2, NH+4, and a small amount of N2O in what appears to be a dismutation reaction. Nitrite and hydrazine were not detected, and N2 and NH+4 were produced in nearly equimolar amounts. The dismutation reaction was first order in [Hb+] and [NH2OH] only at low concentrations of reactants and was cleanly inhibited by cyanide. The spectrum of Hb+ remained unchanged during the reaction, except for the gradual formation of some choleglobin-like (green) pigment, whereas in the presence of CO, HbCO was formed. Kinetics are consistent with the view advanced previously by J. S. Colter and J. H. Quastel [1950) Arch. Biochem. 27, 368-389) that the decomposition of NH2OH proceeds by a mechanism involving a Hb/Hb+ cycle (reactions [1] and [2]) in which Hb is oxidized to Hb+ by NH2OH.

  4. Local Fractional Adomian Decomposition and Function Decomposition Methods for Laplace Equation within Local Fractional Operators

    Directory of Open Access Journals (Sweden)

    Sheng-Ping Yan

    2014-01-01

    Full Text Available We perform a comparison between the local fractional Adomian decomposition and local fractional function decomposition methods applied to the Laplace equation. The operators are taken in the local sense. The results illustrate the significant features of the two methods which are both very effective and straightforward for solving the differential equations with local fractional derivative.

  5. Thermal Behaviour of Some Azo Dyes Containing Sterically Hindered and Water-Soluble Groups

    OpenAIRE

    KOCAOKUTGEN, Hasan; HEREN, Zerrin

    1998-01-01

    Thermal behaviour of six azo dyes containing steric hindered groups such as tert-butyl, sec-butyl and isopropyl, were investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and differential thermogravimetry (DTG). The thermal decomposition points and amount of volatile pyrolysis products, were determined in nitrogen atmosphere using TG, DTA and DTG curves.

  6. Fast approximate convex decomposition using relative concavity

    KAUST Repository

    Ghosh, Mukulika

    2013-02-01

    Approximate convex decomposition (ACD) is a technique that partitions an input object into approximately convex components. Decomposition into approximately convex pieces is both more efficient to compute than exact convex decomposition and can also generate a more manageable number of components. It can be used as a basis of divide-and-conquer algorithms for applications such as collision detection, skeleton extraction and mesh generation. In this paper, we propose a new method called Fast Approximate Convex Decomposition (FACD) that improves the quality of the decomposition and reduces the cost of computing it for both 2D and 3D models. In particular, we propose a new strategy for evaluating potential cuts that aims to reduce the relative concavity, rather than absolute concavity. As shown in our results, this leads to more natural and smaller decompositions that include components for small but important features such as toes or fingers while not decomposing larger components, such as the torso, that may have concavities due to surface texture. Second, instead of decomposing a component into two pieces at each step, as in the original ACD, we propose a new strategy that uses a dynamic programming approach to select a set of n c non-crossing (independent) cuts that can be simultaneously applied to decompose the component into n c+1 components. This reduces the depth of recursion and, together with a more efficient method for computing the concavity measure, leads to significant gains in efficiency. We provide comparative results for 2D and 3D models illustrating the improvements obtained by FACD over ACD and we compare with the segmentation methods in the Princeton Shape Benchmark by Chen et al. (2009) [31]. © 2012 Elsevier Ltd. All rights reserved.

  7. Two Notes on Discrimination and Decomposition

    DEFF Research Database (Denmark)

    Nielsen, Helena Skyt

    1998-01-01

    1. It turns out that the Oaxaca-Blinder wage decomposition is inadequate when it comes to calculation of separate contributions for indicator variables. The contributions are not robust against a change of reference group. I extend the Oaxaca-Blinder decomposition to handle this problem. 2. The p....... The paper suggests how to use the logit model to decompose the gender difference in the probability of an occurrence. The technique is illustrated by an analysis of discrimination in child labor in rural Zambia....

  8. Vector domain decomposition schemes for parabolic equations

    Science.gov (United States)

    Vabishchevich, P. N.

    2017-09-01

    A new class of domain decomposition schemes for finding approximate solutions of timedependent problems for partial differential equations is proposed and studied. A boundary value problem for a second-order parabolic equation is used as a model problem. The general approach to the construction of domain decomposition schemes is based on partition of unity. Specifically, a vector problem is set up for solving problems in individual subdomains. Stability conditions for vector regionally additive schemes of first- and second-order accuracy are obtained.

  9. Claw-decompositions and Tutte-orientations

    DEFF Research Database (Denmark)

    Barat, Janos; Thomassen, Carsten

    2006-01-01

    We conjecture that, for each tree T there exists a natural number k(T) such that the following holds: If G is a k(T)-edge-connected graph such that \\E(T)\\ divides \\EG)\\, then the edges of G can be divided into parts, each of which is isomorphic to T. We prove that for T=K-1,K-3 (the claw), this h......]-edge-connected graph with n vertices has an edge-decomposition into claws provided its number of edges is divisible by 3. We also prove that every triangulation of a surface has an edge-decomposition into claws. (C) 2006 Wiley Periodicals, Inc....

  10. Surface Modes of Coherent Spinodal Decomposition

    Science.gov (United States)

    Tang, Ming; Karma, Alain

    2012-06-01

    We use linear stability theory and numerical simulations to show that spontaneous phase separation in elastically coherent solids is fundamentally altered by the presence of free surfaces. Because of misfit stress relaxation near surfaces, phase separation is mediated by unique surface modes of spinodal decomposition that have faster kinetics than bulk modes and are unstable even when spinodal decomposition is suppressed in the bulk. Consequently, in the presence of free surfaces, the limit of metastability of supersaturated solid solutions of crystalline materials is shifted from the coherent to chemical spinodal.

  11. Multiresolution signal decomposition transforms, subbands, and wavelets

    CERN Document Server

    Akansu, Ali N; Haddad, Paul R

    2001-01-01

    The uniqueness of this book is that it covers such important aspects of modern signal processing as block transforms from subband filter banks and wavelet transforms from a common unifying standpoint, thus demonstrating the commonality among these decomposition techniques. In addition, it covers such ""hot"" areas as signal compression and coding, including particular decomposition techniques and tables listing coefficients of subband and wavelet filters and other important properties.The field of this book (Electrical Engineering/Computer Science) is currently booming, which is, of course

  12. Decomposition of aquatic plants in lakes

    Energy Technology Data Exchange (ETDEWEB)

    Godshalk, G.L.

    1977-01-01

    This study was carried out to systematically determine the effects of temperature and oxygen concentration, two environmental parameters crucial to lake metabolism in general, on decomposition of five species of aquatic vascular plants of three growth forms in a Michigan lake. Samples of dried plant material were decomposed in flasks in the laboratory under three different oxygen regimes, aerobic-to-anaerobic, strict anaerobic, and aerated, each at 10/sup 0/C and 25/sup 0/C. In addition, in situ decomposition of the same species was monitored using the litter bag technique under four conditions.

  13. Assessment of skeletal changes after post-mortem exposure to fire as an indicator of decomposition stage.

    Science.gov (United States)

    Keough, N; L'Abbé, E N; Steyn, M; Pretorius, S

    2015-01-01

    Forensic anthropologists are tasked with interpreting the sequence of events from death to the discovery of a body. Burned bone often evokes questions as to the timing of burning events. The purpose of this study was to assess the progression of thermal damage on bones with advancement in decomposition. Twenty-five pigs in various stages of decomposition (fresh, early, advanced, early and late skeletonisation) were exposed to fire for 30 min. The scored heat-related features on bone included colour change (unaltered, charred, calcined), brown and heat borders, heat lines, delineation, greasy bone, joint shielding, predictable and minimal cracking, delamination and heat-induced fractures. Colour changes were scored according to a ranked percentage scale (0-3) and the remaining traits as absent or present (0/1). Kappa statistics was used to evaluate intra- and inter-observer error. Transition analysis was used to formulate probability mass functions [P(X=j|i)] to predict decomposition stage from the scored features of thermal destruction. Nine traits displayed potential to predict decomposition stage from burned remains. An increase in calcined and charred bone occurred synchronously with advancement of decomposition with subsequent decrease in unaltered surfaces. Greasy bone appeared more often in the early/fresh stages (fleshed bone). Heat borders, heat lines, delineation, joint shielding, predictable and minimal cracking are associated with advanced decomposition, when bone remains wet but lacks extensive soft tissue protection. Brown burn/borders, delamination and other heat-induced fractures are associated with early and late skeletonisation, showing that organic composition of bone and percentage of flesh present affect the manner in which it burns. No statistically significant difference was noted among observers for the majority of the traits, indicating that they can be scored reliably. Based on the data analysis, the pattern of heat-induced changes may

  14. Distributed Model Predictive Control via Dual Decomposition

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Stoustrup, Jakob; Andersen, Palle

    2014-01-01

    This chapter presents dual decomposition as a means to coordinate a number of subsystems coupled by state and input constraints. Each subsystem is equipped with a local model predictive controller while a centralized entity manages the subsystems via prices associated with the coupling constraints...

  15. Domain decomposition methods for hyperbolic problems

    Indian Academy of Sciences (India)

    problems using domain decomposition but this technique faces difficulties if the system becomes characteristic at the inter-element boundaries. By making the inter-element boundaries move faster than the fastest wave speed associated with the hyperbolic system we are able to overcome this problem. Keywords. Domain ...

  16. Domain decomposition methods for hyperbolic problems

    Indian Academy of Sciences (India)

    In this paper a method is developed for solving hyperbolic initial boundary value problems in one space dimension using domain decomposition, which can be extended to problems in several space dimensions. We minimize a functional which is the sum of squares of the 2 norms of the residuals and a term which is the ...

  17. KINETICS OF HYDROXIDE PHOMOTED DECOMPOSITION 0F ...

    African Journals Online (AJOL)

    1991-04-26

    (Received July 2?. 1990; revised April 26, 1991). ABSTRACT. The effects of varying concentrations of dimethyl sulphoxide in mixture with water on rates and activation parameters for the hydroxide promoted decomposition of tetraphenylphosphonium chloride have been studied. Increasing the DMSO content of the reaction ...

  18. The decomposition of estuarine macrophytes under different ...

    African Journals Online (AJOL)

    The estuary is subject to a variety of anthropogenic impacts (e.g. freshwater abstraction and sewage discharge) that increases its susceptibility to prolonged periods of mouth closure, eutrophication, and ultimately the formation of macroalgal blooms. The aim of this study was to determine the decomposition characteristics of ...

  19. Direct observation of nanowire growth and decomposition

    DEFF Research Database (Denmark)

    Rackauskas, Simas; Shandakov, Sergey D; Jiang, Hua

    2017-01-01

    knowledge, so far this has been only postulated, but never observed at the atomic level. By means of in situ environmental transmission electron microscopy we monitored and examined the atomic layer transformation at the conditions of the crystal growth and its decomposition using CuO nanowires selected...

  20. Organic matter decomposition in simulated aquaculture ponds

    NARCIS (Netherlands)

    Torres Beristain, B.

    2005-01-01

    Different kinds of organic and inorganic compounds (e.g. formulated food, manures, fertilizers) are added to aquaculture ponds to increase fish production. However, a large part of these inputs are not utilized by the fish and are decomposed inside the pond. The microbiological decomposition of the