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Sample records for thermal decomposition characters

  1. Structure, optical and thermal decomposition characters of LDPE ...

    Indian Academy of Sciences (India)

    Administrator

    Nowadays, the modification of polymers covers radiation cross-linking, radiation induced polymerization (graft polymerization and curing) and the degradation of poly- mers. Among these, are the modified mechanical, thermal, electrical, and optical properties to fulfill the required characteristics for such goods as packaging ...

  2. Thermal decomposition of pyrite

    International Nuclear Information System (INIS)

    Music, S.; Ristic, M.; Popovic, S.

    1992-01-01

    Thermal decomposition of natural pyrite (cubic, FeS 2 ) has been investigated using X-ray diffraction and 57 Fe Moessbauer spectroscopy. X-ray diffraction analysis of pyrite ore from different sources showed the presence of associated minerals, such as quartz, szomolnokite, stilbite or stellerite, micas and hematite. Hematite, maghemite and pyrrhotite were detected as thermal decomposition products of natural pyrite. The phase composition of the thermal decomposition products depends on the terature, time of heating and starting size of pyrite chrystals. Hematite is the end product of the thermal decomposition of natural pyrite. (author) 24 refs.; 6 figs.; 2 tabs

  3. Thermal decomposition of lutetium propionate

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2010-01-01

    The thermal decomposition of lutetium(III) propionate monohydrate (Lu(C2H5CO2)3·H2O) in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy and X-ray diffraction. Dehydration takes place around 90 °C. It is followed by the decomposition of the anhydrous ...... of the oxycarbonate to the rare-earth oxide proceeds in a different way, which is here reminiscent of the thermal decomposition path of Lu(C3H5O2)·2CO(NH2)2·2H2O...

  4. Thermal decomposition of ammonium hexachloroosmate

    DEFF Research Database (Denmark)

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

    2016-01-01

    Structural changes of (NH4)2[OsCl6] occurring during thermal decomposition in a reduction atmosphere have been studied in situ using combined energy-dispersive X-ray absorption spectroscopy (ED-XAFS) and powder X-ray diffraction (PXRD). According to PXRD, (NH4)2[OsCl6] transforms directly...

  5. Solid state exchange reactions and thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Albarran, G.; Archundia, C.; Maddock, A.G.

    1982-01-01

    A further study of exchange of the cobalt atoms in solid Co(H/sub 2/O)/sub 6/(Co EDTA)/sub 2/ x 4H/sub 2/O has been made. The exchange is more easily measured when the compound has been ..gamma.. irradiated before heating. Without irradiation the exchange is complicated by substantial concurrent thermal decomposition. Vacuum dehydration to the tetrahydrate can be effected at 366 K without appreciable exchange. A relation between exchange, annealing of radiolytic decomposition and thermal decomposition in such compounds is suggested.

  6. Thermal decomposition of biphenyl (1963)

    International Nuclear Information System (INIS)

    Clerc, M.

    1962-06-01

    The rates of formation of the decomposition products of biphenyl; hydrogen, methane, ethane, ethylene, as well as triphenyl have been measured in the vapour and liquid phases at 460 deg. C. The study of the decomposition products of biphenyl at different temperatures between 400 and 460 deg. C has provided values of the activation energies of the reactions yielding the main products of pyrolysis in the vapour phase. Product and Activation energy: Hydrogen 73 ± 2 kCal/Mole; Benzene 76 ± 2 kCal/Mole; Meta-triphenyl 53 ± 2 kCal/Mole; Biphenyl decomposition 64 ± 2 kCal/Mole; The rate of disappearance of biphenyl is only very approximately first order. These results show the major role played at the start of the decomposition by organic impurities which are not detectable by conventional physico-chemical analysis methods and the presence of which accelerates noticeably the decomposition rate. It was possible to eliminate these impurities by zone-melting carried out until the initial gradient of the formation curves for the products became constant. The composition of the high-molecular weight products (over 250) was deduced from the mean molecular weight and the dosage of the aromatic C - H bonds by infrared spectrophotometry. As a result the existence in tars of hydrogenated tetra, penta and hexaphenyl has been demonstrated. (author) [fr

  7. Thermal decomposition process of silver behenate

    International Nuclear Information System (INIS)

    Liu Xianhao; Lu Shuxia; Zhang Jingchang; Cao Weiliang

    2006-01-01

    The thermal decomposition processes of silver behenate have been studied by infrared spectroscopy (IR), X-ray diffraction (XRD), combined thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS), transmission electron microscopy (TEM) and UV-vis spectroscopy. The TG-DTA and the higher temperature IR and XRD measurements indicated that complicated structural changes took place while heating silver behenate, but there were two distinct thermal transitions. During the first transition at 138 deg. C, the alkyl chains of silver behenate were transformed from an ordered into a disordered state. During the second transition at about 231 deg. C, a structural change took place for silver behenate, which was the decomposition of silver behenate. The major products of the thermal decomposition of silver behenate were metallic silver and behenic acid. Upon heating up to 500 deg. C, the final product of the thermal decomposition was metallic silver. The combined TG-MS analysis showed that the gas products of the thermal decomposition of silver behenate were carbon dioxide, water, hydrogen, acetylene and some small molecule alkenes. TEM and UV-vis spectroscopy were used to investigate the process of the formation and growth of metallic silver nanoparticles

  8. Thermal Decomposition of Aluminium Chloride Hexahydrate

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar; Šolcová, Olga

    2005-01-01

    Roč. 44, č. 17 (2005), s. 6591-6598 ISSN 0888-5885 R&D Projects: GA ČR(CZ) GA203/02/0002 Institutional research plan: CEZ:AV0Z40720504 Keywords : aluminum chloride hexahydrate * thermal decomposition * reaction kinetics Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.504, year: 2005

  9. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    TECS

    SEM observation of the heat-treated samples at 950°C shows cluster of grains, indicating the structural transformation. Keywords. TGA–DTA; FTIR; X-ray diffraction; dolomite. 1. Introduction. Dolomite typically occurs as the major constituent of sedimentary formations in association with calcite. Thermal analysis might offer ...

  10. Thermal decomposition of dinitratobis(carbamido) uranyl

    International Nuclear Information System (INIS)

    Kobets, L.V.; Kostyukov, N.N.; Umrejko, D.S.

    1987-01-01

    Thermal stability of dinitratobis (carbamido) uranyl was investigated by the methods of DTA, TG and isothermal heatings at different temperatures. It was revealed that urea as a whole was not removed from the complex. Urea loses ammonia simultaneously with substance melting (498K); biuret and cyanuric acid form at that. Ammonia removal to gaseous phase decelerates in 573-593 K range due to its binding with formation of amination products. Decomposition of nitrate groups begins at temperatures above 570 K. Heating products were studied by the methods of vibrational spectroscopy, chemical and X-ray phase analyses. Ideas about mechanism of decomposition were considered

  11. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

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

    2015-01-01

    degrees C and evidence was found for the solidification of the melt at 380-440 degrees C, i.e. simultaneously with the onset of decomposition. Between 400 degrees C and 520 degrees C (Ba(C4H9CO2)(2) decomposes in two main steps, first into BaCO3 with release of C4H9COC4H9 (5-nonanone), whereas final......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...

  12. 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.

  13. Thermal decomposition of 2-methylbenzoates of rare earth elements

    International Nuclear Information System (INIS)

    Brzyska, W.; Szubartowski, L.

    1980-01-01

    The conditions of thermal decomposition of La, Ce(3), Pr, Nd, Sm and Y 2-methylbenzoates were examined. On the basis of obtained results it was stated that hydrated 2-methylbenzoates were subjected to dehydration passing into anhydrated salts and then they decomposed into oxides. The activation energy of dehydration and decomposition reactions of lanthanons, La and Y 2-methylbenzoates was determined. (author)

  14. Thermal decomposition of Co–Al layered double hydroxide ...

    Indian Academy of Sciences (India)

    Administrator

    In this, paper, we study the thermal decomposition of the Co–Al–. CO. 2. 3. –. LDH by in situ variable temperature powder X-ray diffraction (VTPXRD), and follow the structural changes taking place in the LDH prior to the decomposition reac- tion. We report the formation of a precursor hydroxide phase having a topochemical ...

  15. 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...

  16. Structure, optical and thermal decomposition characters of LDPE ...

    Indian Academy of Sciences (India)

    Administrator

    However, the XRD peaks corresponding to the crystalline reflections for the graft copolymer appeared at identical diffraction angles as in blank LDPE. These results sug- gested that the inherent crystallinity of the backbone polymer was not employed by the graft copolymerization of MMA and that the grafting occurred only in ...

  17. 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...

  18. Intensification of thermal decomposition of sodium and calcium hypochlorite

    OpenAIRE

    Знак, Зеновий Орестович; Гнатишин, Надежда Михайловна

    2010-01-01

    The process of decomposition of sodium and calcium hypochlorite by thermal and cavitation methods is investigated. It is found that the rate of decomposition of hypochlorite increases sharply due to changes in method of heat supply: the bubbling of vapour in the bulk solution to the dispersion of the solution in the volume of vapour, and also due to the activation of the cavitation process.

  19. Synthesis and thermal decomposition study of dysprosium trifluoroacetate

    DEFF Research Database (Denmark)

    Opata, Y. A.; Grivel, J.-C.

    2018-01-01

    A study of the thermal decomposition process of dysprosium trifluoroacetate hydrate under flowing argon is presented. Thermogravimetry, differential thermal analysis, evolved gas analysis and ex-situ x-ray diffraction techniques have been employed in the investigation. Three main stages were...... at temperatures just above the decomposition step and at 828 °C showed a variation in the sample color, being dark in the first case and rather bright at the higher quenching temperature. Based on this fact, we concluded that some carbon remains in the sample up to 800 °C. With the temperature reaching 1300 °C...

  20. Thermal decomposition of silane to form hydrogenated amorphous Si film

    Science.gov (United States)

    Strongin, Myron; Ghosh, Arup K.; Wiesmann, Harold J.; Rock, Edward B.; Lutz, III, Harry A.

    1980-01-01

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silano (SiH.sub.4) or other gases comprising H and Si, at elevated temperatures of about 1700.degree.-2300.degree. C., and preferably in a vacuum of about 10.sup.-8 to 10.sup.-4 torr, to form a gaseous mixture of atomic hydrogen and atomic silicon, and depositing said gaseous mixture onto a substrate outside said source of thermal decomposition to form hydrogenated amorphous silicon.

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

    Indian Academy of Sciences (India)

    DTA and TGA curves of titanium hydride powder were determined in air at different heating rates. Also the thermal decomposition behaviour of the aforementioned powder at high heating rates was taken into consideration. A great breakthrough of the practical interest in the research was the depiction of the H2-time curves ...

  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 and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as ...

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

    Indian Academy of Sciences (India)

    Unknown

    )2]⋅3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as ...

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

    Indian Academy of Sciences (India)

    Unknown

    (Hojo and Ishizaka 1997) can also prepare WSi2 powder. In this paper, nanocrystalline tungsten disilicide has been synthesized by a convenient thermal decomposition- co-reduction route via the reaction of metallic potassium with sodium fluorosilicate and tungsten hexachloride in an autoclave at 650°C. This reaction can ...

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

    Indian Academy of Sciences (India)

    Nanocrystalline WSi2 was synthesized by a thermal decomposition-co-reduction route via the reaction of anhydrous tungsten hexachloride and sodium fluorosilicate with metallic potassium in an autoclave at 650°C. X-ray powder diffraction pattern indicated that it was tetragonal WSi2. Transmission electron microscope ...

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

    African Journals Online (AJOL)

    NJD

    m-Methylbenzoic acid, 1,10-phenanthroline, dysprosium complex, crystal structure, thermal analysis. 1. Introduction. The complexes of rare earth ions and aromatic carboxylic acids have various coordination modes, and various crystal structures, which show interesting polymeric networks or chain struc- tures.1–3 They are ...

  7. The radiation and thermal decomposition of terphenyls and hydroterphenyls

    International Nuclear Information System (INIS)

    Tomlinson, M.; Boyd, A.W.; Hatcher, S.R.

    1967-01-01

    Studies of the radiation and thermal decomposition of terphenyls and a hydrogenated terphenyl mixture are summarized. At temperatures up to 350 deg. C the radiolytic decomposition of terphenyls (a) was independent of radiation intensity, (b) increased slightly with temperature, (c) was several times greater for recoil proton radiation than for fast electrons. Above 350 deg. C the decomposition rate during irradiation (a) was greater at low intensities than at high intensities, (b) increased more rapidly with increasing temperature, (c) was independent of the kind of radiation, (d) increased with increasing radiation pulse frequency. These effects have been interpreted in terms of changes in the radiolytic mechanism at higher temperatures. HB-40, a hydrogenated terphenyl was subjected to prolonged irradiation in a small loop under conditions simulating those in a reactor. Decomposition products were removed by batch distillation and recovered coolant was recycled to attain various stationary compositions. These HB-40 coolant mixtures differed in important respects from the HB-40 feed. Rates of consumption of coolant were low, in the range 15 to 20 g consumed per kWh radiation absorbed, at temperatures in the range 250 to 400 deg. C. Thermal degradation of the radiolytic high-boiler products at higher temperatures of irradiation or distillation tended to offset the radiolytic decomposition. (author)

  8. 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

  9. Thermal decomposition of PMC for fiber recovery

    Energy Technology Data Exchange (ETDEWEB)

    Jody, B. J.; Daniels, E. J.; Pomykala, J. A.

    1999-10-22

    This paper describes efforts by Argonne National Laboratory to develop a process to recover carbon fibers from polymer matrix composite (PMC) materials. The polymer material in the matrix maybe a thermoplastic or a thermoset. Samples of panels containing PMC fibers were obtained and used in the bench-scale testing program. The authors tested three different methods for recovering these PMC fibers: thermal treatment, chemical degradation, and cryogenic methods (thermal shock treatment). The first two methods were effective in separating the carbon fibers from the polymeric substrate; the third method was not satisfactory. Carbon fibers separated from the polymer substrate using the thermal treatment method were submitted to Oak Ridge National Laboratory for analysis and evaluation. The results indicated that the carbon fibers had been cleanly separated from the polymer matrix. Their intrinsic density was 1.8473 g/cm{sup 3} and their electrical resistivity was 0.001847 ohm-cm, compared to an intrinsic density of 1.75--1.9 gm/cm{sup 3} and an electrical resistivity of 0.0002--0.002 ohm-cm for virgin fibers produced from polyacrylonitrile (PAN). Although they were not sure that the samples they processed were originally produced from PAN, they used the PAN fibers for comparison. It was also demonstrated that the surface of the recovered fibers could be reactivated to energy levels equivalent to those of reactivated virgin fibers from PAN. A comparison of the mechanical properties of the recovered fibers (without surface treatment) with those of surface-treated virgin fibers from PAN revealed that the ultimate tensile strength and the elongation at brake values are about 1/3 the values for the virgin fibers. The modulus for the recycled fibers (31.4 million pounds per square inch [psi]) was about the same as that for the virgin PAN fibers (31.2 million psi). The reason for the lower tensile strength and elongation is not clear; the authors plan to investigate it further

  10. 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.

  11. Thermal Decomposition Characteristics of ADU Gel Spheres

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Kyung Chai; Eom, Sung Ho; Kim, Yeon Ku; Kim, Young Min; Kim, Woong Ki; Kim, Bong Ku; Lee, Young Woo; Cho, Moon Seoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    HTGR nuclear fuel uses a modified sol.gel GSP (Gel Supported Precipitation) method, which is a wet method used in most countries. ADU(Ammonium DiUranate) gel particles fabricated in this way pass through thermal treatments and become final UO{sub 2} microspheres. The washing characteristics such as washing volume, duration, and times during AWD(ageing, washing and drying) process after the spherical ADU gel particles preparation by the GSP method was studied. The VHTR (Very High Temperature Gas Reactor) is one of the reactor concepts in the Gen IV International Collaboration. Unlike light water reactor currently in use in Korea, a HTGR actually functions as a gas cooled reactor where the high temperature heat generated from nuclear fission in a reactor is cooled by He gas, with uranium dioxide (UO{sub 2} is globally used) used as fuel for the nuclear fission. Generally, nuclear fuel used in a HTGR is fabricated into a TRISO (TRi.ISOtropic) structure that can prevent the leakage of nuclear fission products at high temperatures.

  12. Direct observation of thermal disorder and decomposition of black phosphorus

    Science.gov (United States)

    Yoo, Seung Jo; Kim, Heejin; Lee, Ji-Hyun; Kim, Jin-Gyu

    2018-02-01

    Theoretical research has been devoted to reveal the properties of black phosphorus as a two-dimensional nanomaterial, but little attention has been paid for the experimental characterization. In this study, the thermal disorder and decomposition of black phosphorus were examined using in situ heating transmission electron microscopy experiments. We observed that the breaking of crystallographic symmetry begins at 380 °C under vacuum condition, followed by the phosphorus evaporates after long-term heating at 400 °C. This decomposition process can be initiated by the surficial vacancy and proceeds toward both interlayer ([010]) and intralayer ([001]) directions. The results on the thermal behavior of black phosphorus provide useful guidance for thin film deposition and fabrication processes with black phosphorus.

  13. Thermal decomposition of yttrium(III) propionate and butyrate

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2013-01-01

    The thermal decompositions of yttrium(III) propionate monohydrate (Y(C2H5CO2)3·H2O) and yttrium(III) butyrate dihydrate (Y(C3H7CO2)3·2H2O) were studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage microscopy. These two...... compounds follow a similar decomposition path starting with dehydration, which is complete at 110°C. The dehydrated salts convert to a dioxycarbonate (Y2O2CO3) via an unstable intermediate product (probably Y2O(C2H5CO2)4 and Y2O(C3H7CO2)4 for the propionate and butyrate respectively), with the evolution...... in anhydrous yttrium butyrate, whereas no melting was evidenced in the propionate. © 2013 Elsevier B.V. All rights reserved....

  14. Thermal decomposition of yttrium(III) valerate in argon

    DEFF Research Database (Denmark)

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

    2014-01-01

    The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting...... takes place around 90 °C and evidence was found for solidification of the melt at 260–300 °C, i.e. close to the onset of decomposition. Between 300 °C and 450 °C, Y(C4H9CO2)3 decomposes in a single step into Y2O2CO3 with release of gaseous CO2 and C4H9COC4H9 (5-nonanone). Final conversion to Y2O3 takes...

  15. Thermal Decomposition Kinetics of Labile Chromium Complex with Benzoic Acid

    OpenAIRE

    Mishra, M. K.; Misra, N. M.

    2011-01-01

    Complex [CrO2 (C7H5O2) C2H5OH) (H2O)2] was prepared by using benzoic acid. Its spectral characterization was done by using Elemental analysis (C and H), Inductively coupled plasma optical emission spectroscopy (ICP - OES), Ultraviolet - visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and Fast Atomic Bombardment (FAB) Mass spectrometry. Whereas thermal decomposition was investigated by differential scanning calorimetric (DSC). The low value of activation energy of...

  16. Quantum chemical aided prediction of the thermal decomposition mechanisms and temperatures of ionic liquids

    International Nuclear Information System (INIS)

    Kroon, Maaike C.; Buijs, Wim; Peters, Cor J.; Witkamp, Geert-Jan

    2007-01-01

    The long-term thermal stability of ionic liquids is of utmost importance for their industrial application. Although the thermal decomposition temperatures of various ionic liquids have been measured previously, experimental data on the thermal decomposition mechanisms and kinetics are scarce. It is desirable to develop quantitative chemical tools that can predict thermal decomposition mechanisms and temperatures (kinetics) of ionic liquids. In this work ab initio quantum chemical calculations (DFT-B3LYP) have been used to predict thermal decomposition mechanisms, temperatures and the activation energies of the thermal breakdown reactions. These quantum chemical calculations proved to be an excellent method to predict the thermal stability of various ionic liquids

  17. Thermal decomposition of anhydrous zinc and cadmium salicylates

    International Nuclear Information System (INIS)

    Kharitonov, Yu.Ya.; Tujebakhova, Z.K.

    1984-01-01

    On the basis of studying thermograms, thermogravigrams, IR absorption spectra, X-rayograms of anhydrous znc and cadmium salicylate complexes of the M(HSal) 2 composition, (where M=Zn, Cd; HSal is an anion of once deprotonated salicyclic acid H 2 Sal) and products of their thermal transformations, the processes are characterized of stage-by-stage thermal decomposition of these compounds under continuous heating in the air from room temperature to approximately 1000 deg C. It is shown that the Cd(HSal) 2 pyrolysis proceeds with the formation of CdSal at 170-250 deg C and CdO - at 320-460 deg C

  18. Kinetics of the thermal decomposition of nickel iodide

    International Nuclear Information System (INIS)

    Nakajima, Hayato; Shimizu, Saburo; Onuki, Kaoru; Ikezoe, Yasumasa; Sato, Shoichi

    1984-01-01

    Thermal decomposition kinetics of NiI 2 under constant I 2 partial pressure was studied by thermogravimetry. The reaction is considered as a reaction step of the thermochemical hydrogen production process in the Ni-I-S system. At temperatures from 775K to 869K and under I 2 pressures from 0 to 960Pa, the decomposition started at the NiI 2 pellet surface and the reactant-product interface moved interior at a constant rate until the decomposed fraction, α, reached 0.6. The overall reaction rate at a constant temperature can be expressed as the difference of the constant decomposition (forward) rate, which is proportional to the equilibrium dissociation pressure of NiI 2 , and the iodide formation (backward) rate, which is proportional to the I 2 pressure. The apparent activation energy of the decomposition was 147 kJ.mol -1 , which is very close to the heat of reaction, 152 kJ.mol -1 calculated from the equilibrium dissociation pressure. The electron microscopic observations, revealed that the reaction product obtained by decomposing NiI 2 under pure He atomosphere was composed of relatively well grown cubic Ni crystals. Whereas, the decomposed product obtained under I 2 -He mixture was composed of larger but disordered crystals. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Grivel, J.-C., E-mail: jean@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Zhao, Y.; Tang, X.; Pallewatta, P.G.P.A. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Watenphul, A.; Zimmermann, M. von [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany)

    2013-08-20

    Highlights: • The dehydration of La(C{sub 3}H{sub 7}CO{sub 2}){sub 3}·xH{sub 2}O takes place between 50 °C and 120 °C. • La(C{sub 3}H{sub 7}CO{sub 2}){sub 3} melts at 180 °C. • The decomposition of La(C{sub 3}H{sub 7}CO{sub 2}){sub 3} to La{sub 2}O{sub 2}CO{sub 3} involves a meta-butyrate intermediate. • CO{sub 2} and C{sub 3}H{sub 7}COC{sub 3}H{sub 7} (4-heptanone) are released between 250 °C and 350 °C. • La{sub 2}O{sub 3} is formed as a final decomposition product. - Abstract: The thermal decomposition of La(C{sub 3}H{sub 7}CO{sub 2}){sub 3}·xH{sub 2}O (x ≈ 0.82) was studied in argon during heating at 5 K/min. After the loss of bound H{sub 2}O, 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 is associated to a solidification process. The final decomposition to La{sub 2}O{sub 3} takes place via two intermediate products: La{sub 2}O(C{sub 3}H{sub 7}CO{sub 2}){sub 4} and La{sub 2}O{sub 2}CO{sub 3} with release of CO{sub 2} and the symmetrical ketone C{sub 3}H{sub 7}COC{sub 3}H{sub 7}.

  20. Thermal image filtering by bi-dimensional empirical mode decomposition

    Science.gov (United States)

    Gavriloaia, Bogdan-Mihai; Vizireanu, Constantin-Radu; Fratu, Octavian; Mara, Constantin; Vizireanu, Dragos-Nicolae; Preda, Radu; Gavriloaia, Gheorghe

    2015-02-01

    The abnormal function of cells can be detected by anatomic or physiological registrations. Most of modern approaches, as ultrasound, RMN or CT, show anatomic parametric modifications of tissues or organs. They highlight areas with a larger diameter 1 cm. In the case of skin or superficial cancers, local temperature is different, and it can be put out by thermal imager. Medical imaging is a leading role in modern diagnosis for abnormal or normal tissues or organs. Some information has to be improved for a better diagnosis by reducing or removing some unwanted information like noise affecting image texture. The traditional technologies for medical image enhancement use spatial or frequency domain methods, but whole image processing will hide both partial and specific information for human signals. A particular kind of medical images is represented by thermal imaging. Recently, these images were used for skin or superficial cancers diagnosis, but very clear outlines of certain alleged affected areas need to be shown. Histogram equalization cannot highlights the edges and control the effects of enhancement. A new filtering method was introduced by Huang by using the empirical mode decomposition, EMD. An improved filtering method for thermal images, based on EMD, is presented in this paper, and permits to analyze nonlinear and non-stationary data by the adaptive decomposition into intrinsic mode surfaces. The results, evaluated by SNR ratios, are compared with other filtering methods.

  1. 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.

  2. Thermal Decomposition Kinetics of Labile Chromium Complex with Benzoic Acid

    Directory of Open Access Journals (Sweden)

    M. K. Mishra

    2011-01-01

    Full Text Available Complex [CrO2 (C7H5O2 C2H5OH (H2O2] was prepared by using benzoic acid. Its spectral characterization was done by using Elemental analysis (C and H, Inductively coupled plasma optical emission spectroscopy (ICP - OES, Ultraviolet - visible (UV-Vis spectroscopy, Fourier transform infrared (FTIR spectroscopy and Fast Atomic Bombardment (FAB Mass spectrometry. Whereas thermal decomposition was investigated by differential scanning calorimetric (DSC. The low value of activation energy of exothermic change indicated lability of complex.

  3. 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.

  4. Thermal decomposition of cesium-ethylene-ternary graphite intercalation compounds

    International Nuclear Information System (INIS)

    Matsumoto, R.; Oishi, Y.; Arii, T.

    2010-01-01

    In this paper, the thermal decomposition of air-stable Cs-ethylene-ternary graphite intercalation compounds (GICs) is discussed. The air stability of Cs-GICs is improved remarkably after the absorption of ethylene into their interlayer nanospace, because the ethylene molecules oligomerize and block the movement of Cs atoms. In addition, the evaporation of Cs atoms from the Cs-ethylene-ternary GICs is observed above 400 o C under a N 2 atmosphere of 100 Pa by ion attachment mass spectrometry. Although the results indicate that Cs-ethylene-ternary GICs remain stable up to approximately 400 o C, their thermal stability is not very high as compared to that of Cs-GICs.

  5. Preparation of uranium dioxide by thermal decomposition and direct reduction of ammonium uranate

    International Nuclear Information System (INIS)

    Hernandez R, R.

    1995-01-01

    The thermal decomposition of ammonium uranate has been studied by infrared spectroscopy, and X-ray diffraction. It has been show that ammonia remains in the solid until substantially 350 Centigrade degrees, when gaseous nitrogen is released. It is concluded that compounds derived from the calcination of ammonium uranate at atmospheric pressure, produced amorphous U O 3 at about 350-400 Centigrade degrees and transform to U 3 O 8 via α - U O 3 and/or α - U O 3 . The object of this study was to obtain reliable fundamental information regarding the character of the pure carbon monoxide-ammonium uranate-uranium trioxide-uranium octaoxide reaction, in the range of temperatures that has been used in commercial reduction processes. Through the use of high-purity samples and by the proper control of incidental variable, this object was realized. (Author)

  6. 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.

  7. 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.

  8. 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...

  9. [Effects of fullerene soot on the thermal decomposition and Fourier transform infrared spectrum of PEG].

    Science.gov (United States)

    Han, Xu; Li, Shu-fen; Zhao, Feng-qi; Pan, Qing; Yi, Jian-hua

    2008-12-01

    Effects of fullerene soot (FS) on the thermal decomposition and Fourier transform infrared spectrum (FTIR) of polyethylene glycol (PEG, molecular weight= 20,000) were investigated by thermal analysis (TG-DTG) and in-situ FTIR experiments. The results of thermal analytical experiments showed that the addition of FS postponed not only the initial decomposition temperatures but also the temperatures at maximum decomposition rate of PEG. The maximum decomposition peak temperatures increased and the maximum decomposition rates were lowered even with the addition of 0.1%FS. The in-situ FTIR experiments proved that there was no difference between the IR spectra of PEG and PEG with 10%FS. There wasn't any new chemical band formed but Vander waals force between FS and PEG. Although the addition of FS didn't influence the constitution of decomposition products of PEG, it obviously increased the decomposition temperature and the decomposition rate of PEG. Through the researches on condensed phase and gaseous phase FTIR spectrum of PEG and PEG with 10%FS, one could see that the effect of FS on the condensed phase FTIR spectrum of PEG was not obvious, but the addition of FS markedly enhanced the occurrence temperatures of most gaseous decomposition products of PEG. These results showed that the effect of FS on thermal decomposition of PEG was through the absorbance and desorption of gaseous phase decomposition products. With the temperature elevated, the gaseous products were gradually desorbed from the activity centers and the decomposition of PEG continued. The thermal decomposition peak of PEG was moved toward hi gher temperature with the addition of FS than that without FS.

  10. Thermal decomposition kinetics of sorghum straw via thermogravimetric analysis.

    Science.gov (United States)

    Dhyani, Vaibhav; Kumar, Jitendra; Bhaskar, Thallada

    2017-12-01

    The thermal decomposition of sorghum straw was investigated by non-isothermal thermogravimetric analysis, where the determination of kinetic triplet (activation energy, pre-exponential factor, and reaction model), was the key objective. The activation energy was determined using different isoconversional methods: Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink, Iterative method of Chai & Chen, Vyazovkin AIC method, and Li & Tang equation. The pre-exponential factor was calculated using Kissinger's equation; while the reaction model was predicted by comparison of z-master plot obtained from experimental values with the theoretical plots. The values of activation energy obtained from isoconversional methods were further used for evaluation of thermodynamic parameters, enthalpy, entropy and Gibbs free energy. Results showed three zones of pyrolysis having average activation energy values of 151.21kJ/mol, 116.15kJ/mol, and 136.65kJ/mol respectively. The data was well fitting with two-dimension 'Valensi' model for conversion values from 0 to 0.4 with a coefficient of determination (R 2 ) value of 0.988, and with third order reaction model for values from 0.4 to 0.9 with an R 2 value of 0.843. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The influence of VO2(B nanobelts on thermal decomposition of ammonium perchlorate

    Directory of Open Access Journals (Sweden)

    Zhang Yifu

    2015-09-01

    Full Text Available The influence of vanadium dioxide VO2(B on thermal decomposition of ammonium perchlorate (AP has not been reported before. In this contribution, the effect of VO2(B nanobelts on the thermal decomposition of AP was investigated by the Thermo- Gravimetric Analysis and Differential Thermal Analysis (TG/DTA. VO2(B nanobelts were hydrothermally prepared using peroxovanadium (V complexes, ethanol and water as starting materials. The thermal decomposition temperatures of AP in the presence of I wt.%, 3 wt.% and 6 wt.% of as-obtained VO2thermal decomposition temperature of AP Furthermore, the influence of the corresponding V2Os, which was obtained by thermal treatment of VO2(B nanobelts, on the thermal decomposition of AP was also investigated. The resufs showed that VO2(B nanobelts had a greater influence on the thermal decomposition temperature of AP than that of V2Os.

  12. 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.

  13. [Analysis of the character of film decomposition of methyl methacrylate (MMA) coated urea by infrared spectrum].

    Science.gov (United States)

    Li, Dong-po; Wu, Zhi-jie; Liang, Cheng-hua; Chen, Li-jun; Zhang, Yu-lan; Nie, Yan-xi

    2012-03-01

    The degradability characteristics of film with 4 kinds of methyl methacrylate coated urea amended with inhibitors were analyzed by FITR, which was purposed to supply theoretical basis for applying the FITR analysis method to film decomposition and methyl methacrylate coated urea fertilizers on farming. The result showed that the chemical component, molecule structure and material form of the membrane were not changed because of adding different inhibitors to urea. the main peaks of expressing film degradation process were brought by the -C-H of CH3 & CH2, -OH, C-O, C-C, C-O-C, C=O, C=C flexing vibrancy in asymmetry and symmetry in 3 479-3 195, 2 993--2 873, 1 741-1 564, 1 461-925 and 850-650 cm(-1). The peak value changed from smooth to tip, and from width to narrow caused by chemical structural transform of film The infrared spectrum of 4 kinds of fertilizers was not different remarkably before 60 days, and the film was slowly degraded. But degradation of the film was expedited after 60 days, it was most quickened at 120 day, and the decomposition rate of film was decreased at 310 day. The substantiality change of film in main molecule structure of 4 kinds of fertilizers didn't happen in 310 days. The main component of film materials was degraded most slowly in brown soil. The speed of film degradation wasn't heavily impacted by different inhibitors. The characteristic of film degradation may be monitored entirely by infrared spectrum. The degradation dynamic, chemical structure change, degradation speed difference of the film could be represented through infrared spectrum.

  14. Study on thermal decomposition of calix[4]arene and its application in thermal stability of polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Chennakesavulu, K., E-mail: chennanml@yahoo.com [National Metallurgical Laboratory Madras Centre, CSIR Complex, Taramani, Chennai 600113 (India); Basariya, M. Raviathul; Sreedevi, P.; Bhaskar Raju, G.; Prabhakar, S.; Rao, S. Subba [National Metallurgical Laboratory Madras Centre, CSIR Complex, Taramani, Chennai 600113 (India)

    2011-03-10

    Thermal decomposition kinetics of calix[4]arene (C4) was investigated using thermogravimetric analysis (TGA) and derivative of TG curve (DTG). TG experiments were carried out under static air atmosphere with nominal heating rates of 1.0, 2.5, 5.0 and 10.0 K/min. Model-fitting methods and model-free methods such as Friedman and Ozawa-Flynn-Wall methods were employed to evaluate the kinetic parameters such as activation energy (E{sub a}), exponential factor (ln A) and reaction order (n). To determine the antioxidant property of C4 the non-isothermal kinetics of polypropylene (PP) with C4 as additive was studied. The FTIR, ESR and {sup 13}C NMR CP-MAS techniques were used to propose the decomposition mechanism of C4 in the presence of PP.

  15. Solar thermal decomposition of desalination reject brine for carbon dioxide removal and neutralisation of ocean acidity

    OpenAIRE

    Davies, P.A.

    2015-01-01

    Desalination plants could become net absorbers (rather than net emitters) of CO2. Thermal decomposition of salts in desalination reject brine can yield MgO which, added to the ocean, would take up CO2 through conversion to bicarbonate. The process proposed here comprises dewatering of brine followed by decomposition in a solar receiver using a heliostat field.

  16. Application of isotopic substitution for studing thermal decomposition of silico-12-tungstic acid

    International Nuclear Information System (INIS)

    Khakhinov, V.V.; Pinchuk, I.N.; Tumurova, L.V.; Mokhosoev, M.V.

    1987-01-01

    Using the methods of thermal analysis and isotopic substitution, the mechanism of dehydration and decomposition of silico-12-tungstic acid hydrate is studied. It is found that H-D exchange leads to elevation of temperature of heteropoly acid decomposition. The observed isotopic effect shows that proton transfer is the limiting stage of the reaction

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

    Indian Academy of Sciences (India)

    The decomposition of mixture of selected volatile organic compounds (VOCs) has been studied in a catalytic non-thermal plasma dielectric barrier discharge reactor. The VOCs mixture consisting n-hexane, cyclo-hexane and -xylene was chosen for the present study. The decomposition characteristics of mixture of VOCs ...

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

    Indian Academy of Sciences (India)

    The decomposition of TMS seems to be initiated via Si-C bond cission by forming methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The total rate coefficients obtained for the decomposition of TMS were fit to Arrhenius equation in two different temperature regions 1058–1130K and 1130–1194 K. The temperature ...

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

    Indian Academy of Sciences (India)

    Unknown

    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 mechanism of the aqueous decomposition of Caro's acid was investigated by Ball and ...

  20. Kinetics of Thermal Decomposition of Aluminum Hydride in Argon

    National Research Council Canada - National Science Library

    Ismail, Ismail M; Hawkins, Tom W

    2005-01-01

    ...) in argon atmosphere and to shed light on the mechanism of alane decomposition. Two kinetic models have been successfully developed and used to propose a mechanism for the complete decomposition of alane and to predict its shelf-life during storage...

  1. 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.

  2. Thermal decomposition of UO3-2H20

    International Nuclear Information System (INIS)

    Flament, T.A.

    1998-01-01

    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

  3. Decomposition

    Science.gov (United States)

    Middleton, Beth A.

    2014-01-01

    A cornerstone of ecosystem ecology, decomposition was recognized as a fundamental process driving the exchange of energy in ecosystems by early ecologists such as Lindeman 1942 and Odum 1960). In the history of ecology, studies of decomposition were incorporated into the International Biological Program in the 1960s to compare the nature of organic matter breakdown in various ecosystem types. Such studies still have an important role in ecological studies of today. More recent refinements have brought debates on the relative role microbes, invertebrates and environment in the breakdown and release of carbon into the atmosphere, as well as how nutrient cycling, production and other ecosystem processes regulated by decomposition may shift with climate change. Therefore, this bibliography examines the primary literature related to organic matter breakdown, but it also explores topics in which decomposition plays a key supporting role including vegetation composition, latitudinal gradients, altered ecosystems, anthropogenic impacts, carbon storage, and climate change models. Knowledge of these topics is relevant to both the study of ecosystem ecology as well projections of future conditions for human societies.

  4. 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.

  5. 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...

  6. 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.

  7. Kinetics of thermal decomposition of γ-irradiated and unirradiated complexes of mandelhydroxamic acid

    International Nuclear Information System (INIS)

    Hassan, R.M.; Farid, T.; El-Bellihi, A.A.

    1992-01-01

    The thermal decomposition of γ-irradiated and unirradiated complexes of mandelhydroxamic acid (HMA), Co (HMA) 2 .1/2H 2 O, Mn (HMA) 2 .2H 2 O, Ba (HMA) 2 .2H 2 O and Cd (HMA) 2 .2H 2 O have been studied thermogravimetrically (under isothermal conditions). The thermal dehydration of each complex occured in one step, while the decomposition of dehydrated complexes occured in two steps. The kinetic parameters for dehydration were computed by different models. The thermal dehydration is regulated by random nucleation A 3 for Co-, Mn-, and Cd-complexes and by phase-boundary (R 3 ) for Ba-complex. The effect of γ-irradiation on the kinetic parameters of thermal decomposition is discussed. Radiation did not modify the mechanism of the reaction but accelarated the dehydration steps in the case of Mn- and Co-complexes. (author) 7 refs.; 1 fig.; 4 tabs

  8. 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 ...

  9. 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 ...

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

    Indian Academy of Sciences (India)

    the temperature is very important, the chemical ther- mometric method was used in our investigations. In the present investigation, the reflected shock tempera- tures were determined by the extent of reverse Diels-. Alder decomposition of cyclohexeneto 1,3-butadiene and ethylene, which is added in the reaction mixture to.

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

    International Nuclear Information System (INIS)

    Sotiriou, Georgios A.; Singh, Dilpreet; Zhang, Fang; Chalbot, Marie-Cecile G.; Spielman-Sun, Eleanor; Hoering, Lutz; Kavouras, Ilias G.; Lowry, Gregory V.; Wohlleben, Wendel; Demokritou, Philip

    2016-01-01

    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.

  12. 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.

  13. 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

  14. 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.

  15. Mechanism and kinetics of thermal decomposition of ammoniacal complex of copper oxalate

    International Nuclear Information System (INIS)

    Prasad, R.

    2003-01-01

    A complex precursor has been synthesized by dissolving copper oxalate in liquor ammonia followed by drying. The thermal decomposition of the precursor has been studied in different atmospheres, air/nitrogen. The mechanism of decomposition of the precursor in air is not as simple one as in nitrogen. In nitrogen, it involves endothermic deammoniation followed by decomposition to finely divided elemental particles of copper. Whereas in air, decomposition and simultaneous oxidation of the residual products (oxidative decomposition), make the process complex and relatively bigger particle of cupric oxide are obtained as final product. The products of decomposition in different atmospheres have been characterized by X-ray diffraction and particle size analysis. The stoichiometric formula, Cu(NH 3 ) 2 C 2 O 4 of the precursor is established from elemental analysis and TG measurements, and it is designated as copper amino oxalate (CAO). In nitrogen atmosphere, the deammoniation and decomposition have been found to be zero and first order, respectively. The values of activation energy have been found to be 102.52 and 95.38 kJ/mol for deammoniation and decomposition, respectively

  16. Mechanism and kinetics of thermal decomposition of ammoniacal complex of copper oxalate

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, R

    2003-11-28

    A complex precursor has been synthesized by dissolving copper oxalate in liquor ammonia followed by drying. The thermal decomposition of the precursor has been studied in different atmospheres, air/nitrogen. The mechanism of decomposition of the precursor in air is not as simple one as in nitrogen. In nitrogen, it involves endothermic deammoniation followed by decomposition to finely divided elemental particles of copper. Whereas in air, decomposition and simultaneous oxidation of the residual products (oxidative decomposition), make the process complex and relatively bigger particle of cupric oxide are obtained as final product. The products of decomposition in different atmospheres have been characterized by X-ray diffraction and particle size analysis. The stoichiometric formula, Cu(NH{sub 3}){sub 2}C{sub 2}O{sub 4} of the precursor is established from elemental analysis and TG measurements, and it is designated as copper amino oxalate (CAO). In nitrogen atmosphere, the deammoniation and decomposition have been found to be zero and first order, respectively. The values of activation energy have been found to be 102.52 and 95.38 kJ/mol for deammoniation and decomposition, respectively.

  17. Thermal Decomposition of RP-2 with Stabilizing Additives

    Science.gov (United States)

    2010-04-01

    Air Force Base). APPARATUS The apparatus used for the decomposition reactions is shown in Figure 1. Two thermostatted blocks of 304 stainless steel... AISI designation) were used to control the reaction temperature. Each block was supported on carbon rods in the center of an insulated box. A...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

  18. Thermal decomposition of high-nitrogen energetic compounds: TAGzT and GUzT

    Science.gov (United States)

    Hayden, Heather F.

    The U.S. Navy is exploring high-nitrogen compounds as burning-rate additives to meet the growing demands of future high-performance gun systems. Two high-nitrogen compounds investigated as potential burning-rate additives are bis(triaminoguanidinium) 5,5-azobitetrazolate (TAGzT) and bis(guanidinium) 5,5'-azobitetrazolate (GUzT). Small-scale tests showed that formulations containing TAGzT exhibit significant increases in the burning rates of RDX-based gun propellants. However, when GUzT, a similarly structured molecule was incorporated into the formulation, there was essentially no effect on the burning rate of the propellant. Through the use of simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and Fourier-Transform ion cyclotron resonance (FTICR) mass spectrometry methods, an investigation of the underlying chemical and physical processes that control the thermal decomposition behavior of TAGzT and GUzT alone and in the presence of RDX, was conducted. The objective was to determine why GUzT is not as good a burning-rate enhancer in RDX-based gun propellants as compared to TAGzT. The results show that TAGzT is an effective burning-rate modifier in the presence of RDX because the decomposition of TAGzT alters the initial stages of the decomposition of RDX. Hydrazine, formed in the decomposition of TAGzT, reacts faster with RDX than RDX can decompose itself. The reactions occur at temperatures below the melting point of RDX and thus the TAGzT decomposition products react with RDX in the gas phase. Although there is no hydrazine formed in the decomposition of GUzT, amines formed in the decomposition of GUzT react with aldehydes, formed in the decomposition of RDX, resulting in an increased reaction rate of RDX in the presence of GUzT. However, GUzT is not an effective burning-rate modifier because its decomposition does not alter the initial gas-phase decomposition of RDX. The decomposition of GUzT occurs at temperatures above the melting point

  19. Thermal decomposition of rhenium (5) complexes with 1,2,4-triazole

    International Nuclear Information System (INIS)

    Amindzhanov, A.A.; Gagieva, S.Ch.; Kotegov, K.V.

    1991-01-01

    Processes of thermal decomposition of rhenium (5) complexes with 1,2,4-triazole were studied. Thermolysis products were identified on the basis of data of the element analysis, IR spectra, conductometry and other methods. It is ascertained that at the first stage of thermolysis of hydroxyl-containing monomer complexes removal of water molecules occurs, and at the second one - dimerization process with formation of Re-O-Re group. It is shown that the nature of halide ion practically does not affect the temperature of the start of intensive thermal decomposition of the complexes

  20. Thermal decomposition of Yttrium(III) isovalerate in argon

    DEFF Research Database (Denmark)

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

    2016-01-01

    The thermal behaviour of yttrium(III) isovalerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, FTIR-spectroscopy, hot-stage optical microscopy and X-ray diffraction with a laboratory Cu-tube source as well as with a synchrotron radiation source...

  1. 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

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

    International Nuclear Information System (INIS)

    Sun, Hongyan; Vaghjiani, Ghanshyam L.

    2015-01-01

    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 NH 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 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 reveal the

  3. 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

  4. Thermal decomposition of hydroiodic acid and hydrogen separation

    International Nuclear Information System (INIS)

    Yeheskel, J.; Leger, D.; Courvoisier, P.

    1978-01-01

    The reaction of decomposition of hydroiodic acid is included in a promising water splitting process (sulfur-iodine cycle). An experimental program is running in order to overcome some basic difficulties and data shortcomings which stand in the way of achieving that target. The core of the experimental system is the palladium silver (23% Ag) membrane tube reactor in which the feed gas entered the inner side of the tube. Four series of different kinds of experiments have been performed: 1) diffusion of hydrogen from a pure feed hydrogen stream through the membrane; the results are statistically analyzed due to the present correlations of the H 2 specific permeability as a function of temperature and pressure (up to 600 0 C and 20 bar); 2) separation of hydrogen from a binary feed mixture H 2 -He; a mathematical model is developed for this operation; 3) indication of the poisoning effect of a little amount of hydroiodic acid on the hydrogen pereability; this effect is partly reversible at high temperatures; 4) a performance of one continuous experiment of HI decomposition into the membrane tube at steady pressure and temperature of 8 bar and 500 0 C; the results prove the catalytic activity of the membrane surface

  5. Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

    International Nuclear Information System (INIS)

    Ramesh, Thimmasandra Narayan

    2010-01-01

    The isothermal decomposition of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature leads to the formation of Co 3 O 4 . The phase evolution during the decomposition process was monitored using powder X-ray diffraction. The transformation of cobalt hydroxide to cobalt oxide occurs via three phase mixture while cobalt hydroxynitrate to cobalt oxide occurs through a two phase mixture. The nature of the sample and its preparation method controls the decomposition mechanism. The comparison of topotactical relationship between the precursors to the decomposed product has been reported in relation to polytypism. - Graphical abstract: Isothermal thermal decomposition studies of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature show the metastable phase formed prior to Co 3 O 4 phase.

  6. 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.

  7. Thermal decomposition kinetics of strontium permanganate trihydrate, cadmium permanganate hexahydrate and calcium permanganate pentahydrate crystals

    International Nuclear Information System (INIS)

    Sakurai, K.R.; Schaeffer, D.A.; Herley, P.J.

    1978-01-01

    A thermogravimetric study of the kinetics of thermal nuclei formation and growth has been carried out for the dehydration and decomposition of single crystal strontium permanganate trihydrate, cadmium permanganate hexahydrate, and calcium permanganate pentahydrate. The isothermal dehydration of strontium parmanganate trihydrate occurs in two stages between 50 and 100 0 C. The dehydration kinetics suggest that the two dehydration stages are based on a single-step nucleation process followed by a growth process without nuclei overlap. The resulting activation energies are consistent with the proposed nucleation theory. For the dehydration kinetics of cadmium permanganate hexahydrate, an overlapping nucleation growth mechanism appears to be operating between 30 and 60 0 C. The results are irreproducible for the dehydration of calcium permanganate pentahydrate at 100 0 C. The thermal decomposition studies indicate that the data of the sigmoidal, isothermal fractional decomposition vs. time curves are reproducible for whole and ground crystals of each dehydrated permanganate. All of the data plots contain an induction or slow rate period, an acceleratory and a decay period. The induction period can be shortened by irradiation with 60 Co γ-rays prior to decomposition. Activation energies obtained for all three materials for the various thermal decomposition periods are found to be similar to those published previously on other alkali and alkaline-earth permanganates. (Auth.)

  8. The Effect of the Aminic Substituent on the Thermal Decomposition of Cyclic Dithiocarbamates

    Directory of Open Access Journals (Sweden)

    Cavalheiro Éder T.G.

    1999-01-01

    Full Text Available Thermogravimetric and Differential Scanning Calorimetric investigation of the thermal behaviour of NH4+, Na+, Zn2+, Cd2+ e Pb2+ dithiocarbamates obtained from cyclic amines, is described under nitrogen and air atmospheres in order to investigate the effect of a cyclic ring on the mechanism of decomposition. Intermediates were identified by X-ray Diffraction analysis. Zn2+, Cd2+ e Pb2+ oxysulphates were detected under air atmosphere suggesting the thermal decomposition under these conditions as an alternating synthetic route to prepare those compounds. The final decomposition products were the metallic sulphides under N2 atmosphere while transition metal oxides and sodium sulphate were obtained under air. Melting enthalpies are also reported from DSC data.

  9. Determination of Characteristic Peroids of Suppression of Thermal Decomposition Reaction of Forest Fuel Material by Specialized Software

    Directory of Open Access Journals (Sweden)

    Gumerov Vladislav M.

    2015-01-01

    Full Text Available Experimental studies determining periods of suppression of thermal decomposition reaction of forest combustible materials was carried out by high-speed, cross-correlation cameras and panoramic techniques PIV and IPI under influence of water steam. Conditions and characteristics of reaction termination of thermal decomposition of forest combustible materials under reaction with steam cloud were defined.

  10. Determination of Characteristic Peroids of Suppression of Thermal Decomposition Reaction of Forest Fuel Material by Specialized Software

    OpenAIRE

    Gumerov, Vladislav; Zhdanova, Alena Olegovna; Osmolovskaya, Maria; Strizhak, Pavel Alexandrovich

    2015-01-01

    Experimental studies determining periods of suppression of thermal decomposition reaction of forest combustible materials was carried out by high-speed, cross-correlation cameras and panoramic techniques PIV and IPI under influence of water steam. Conditions and characteristics of reaction termination of thermal decomposition of forest combustible materials under reaction with steam cloud were defined.

  11. 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-...

  12. 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.

  13. 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...

  14. Thermal Decomposition of Sodium Hydrogen Carbonate and Textural Features of Its Calcines

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal

    2013-01-01

    Roč. 52, č. 31 (2013), s. 10619-10626 ISSN 0888-5885 R&D Projects: GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : thermal decomposition * sodium hydrogen carbonate * sodium bicarbonate Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.235, year: 2013

  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. 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)

  17. 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.

  18. Thermal decomposition of silane to form hydrogenated amorphous Si

    Science.gov (United States)

    Strongin, M.; Ghosh, A.K.; Wiesmann, H.J.; Rock, E.B.; Lutz, H.A. III

    Hydrogenated amorphous silicon is produced by thermally decomposing silane (SiH/sub 4/) or other gases comprising H and Si, at elevated temperatures of about 1700 to 2300/sup 0/C, in a vacuum of about 10/sup -8/ to 10/sup -4/ torr. A gaseous mixture is formed of atomic hydrogen and atomic silicon. The gaseous mixture is deposited onto a substrate to form hydrogenated amorphous silicon.

  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. Synthesis and Non-isothermal Thermal Decomposition of Polydiphenyl(diphenylethynylSilane

    Directory of Open Access Journals (Sweden)

    TAN De-xin

    2017-07-01

    Full Text Available Diphenyldiphenylethynylsilane monomer (DPDPES was synthesized with ethyl bromide, diphenyldichlorosilane and phenylacetylene by Grignard reaction. The molecular structure was characterized by FTIR and 1H-NMR spectroscopy. The polymer of polydiphenyl(diphenylethynylsilane (PDPDPES was also prepared by thermal polymerization. Non-isothermal thermal decomposition process of PDPDPES was studied with TG-DTG technology via model method to get thermal decomposition function and the corresponding mechanism which was further verified by model-free method. Results show that the apparent activation energy and the pre-exponential factor are about Ea=245.37kJ/mol and lgA=13.78s-1 obtained by six different kinetic methods, respectively. The mechanism of functions are f(α= 10/23 ·(1-α·[-ln(1-α]-1.3 and g(α=[-ln(1-α]2.3。

  1. DOLOMITE THERMAL-DECOMPOSITION MACROKINETIC MODELS FOR EVALUATION OF THE GASGENERATORS SORBENT SYSTEMS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2015-01-01

    Full Text Available Employing dolomite in the capacity of a sorbent for generator gas purification is of considerable interest nowadays, as it is the impurity of generator gas that causes the major problem for creating cheep and effective co-generator plants. Designing gas purification systems employs simple but physically adequate macrokinetic models of dolomite thermal decomposition.  The  paper  analyzes  peculiarities  of  several  contemporaneous  models  of  dolomite and calcite thermal decomposition and infers on reasonable practicality for creating compact engineering dolomite-decomposition macrokinetic models and universal techniques of these models parameter reconstruction for specific dolomite samples. Such technics can be founded on thermogravimetric data and standard approximation error minimizing algorithms.The author assumes that CO2  evacuation from the reaction zone within the particle may proceed by diffusion mechanism and/or by the Darcy filtration and indicates that functional dependence of the thermal-decomposition rate from the particle sizes and the temperature differs for the specified mechanisms. The paper formulates four macrokinetic models whose correspondence verification is grounded on the experimental data. The author concludes that further work in this direction should proceed with the dolomite samples investigation and selecting the best approximation model describing experimental data in wide range of temperatures, warming up rates and the particle sizes.

  2. 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.

  3. 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.

  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. NMR study of thermal decomposition of lithium tetrahydroaluminate

    International Nuclear Information System (INIS)

    Tarasov, V.P.; Bakum, S.I.; Kuznetsova, S.F.

    1997-01-01

    Pyrolysis of lithium aluminotetrahydrides and deuterides, LiAlH 4 and LiAlD 4 , was studied by 1 H, 7 Li, 27 Al NMR in 20-700 deg C range. 20-30 time constriction of resonance lines of studied nuclei at 170 deg C testifies to melting of the compounds. It is shown that at LiAlD 4 melting point the first stage of pyrolysis is described by two parallel reactions: LiAlD 4 -> LiD + Al + D 2 , LiAlD 4 + LiD -> Li 3 AlD 6 , which proceed with different rates. It was revealed that reactions of lithium hydride (deuteride) with metallic aluminium at temperatures above 400 deg C resulted to formation of intermetallic compounds of LiAl and LiAl 3 composition. LiAl is characterized by higher thermal stability, than LiAl 3 . 20 refs., 6 figs., 2 tabs

  6. Thermal stability and kinetics of decomposition of ammonium nitrate in the presence of pyrite

    International Nuclear Information System (INIS)

    Gunawan, Richard; Zhang Dongke

    2009-01-01

    The interaction between ammonium nitrate based industrial explosives and pyrite-rich minerals in mining operations can lead to the occurrence of spontaneous explosion of the explosives. In an effort to provide a scientific basis for safe applications of industrial explosives in reactive mining grounds containing pyrite, ammonium nitrate decomposition, with and without the presence of pyrite, was studied using a simultaneous Differential Scanning Calorimetry and Thermogravimetric Analyser (DSC-TGA) and a gas-sealed isothermal reactor, respectively. The activation energy and the pre-exponential factor of ammonium nitrate decomposition were determined to be 102.6 kJ mol -1 and 4.55 x 10 7 s -1 without the presence of pyrite and 101.8 kJ mol -1 and 2.57 x 10 9 s -1 with the presence of pyrite. The kinetics of ammonium nitrate decomposition was then used to calculate the critical temperatures for ammonium nitrate decomposition with and without the presence of pyrite, based on the Frank-Kamenetskii model of thermal explosion. It was shown that the presence of pyrite reduces the temperature for, and accelerates the rate of, decomposition of ammonium nitrate. It was further shown that pyrite can significantly reduce the critical temperature of ammonium nitrate decomposition, causing undesired premature detonation of the explosives. The critical temperature also decreases with increasing diameter of the blast holes charged with the explosive. The concept of using the critical temperature as indication of the thermal stability of the explosives to evaluate the risk of spontaneous explosion was verified in the gas-sealed isothermal reactor experiments.

  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. Non-isothermal kinetics studies on the thermal decomposition of zinc hydroxide carbonate

    International Nuclear Information System (INIS)

    Li Zhongjun; Shen Xiaoqing; Feng Xun; Wang Peiyuan; Wu Zhishen

    2005-01-01

    Zinc hydroxide carbonate precursor, Zn 4 CO 3 (OH) 6 .H 2 O, was synthesized from zinc sulfate using ammonium carbonate as a precipitating agent. Thermogravimetry (TG), differential scanning calorimetry (DSC), transmission electronic microscopy (TEM), infrared spectrum (IR) and X-ray diffraction (XRD) were used to characterize the precursor and the decomposed product. Non-isothermal kinetics of the thermal decomposition of zinc hydroxide carbonate were studied in nitrogen. Based on which, the kinetic parameters were obtained through mode-free method and the thermal decomposition mechanism was derived by mains of non-linear regression. The results show that the decomposition of zinc hydroxide carbonate acts as a double-step reaction, A-bar D2B-bar FnC: a reversible reaction of two-dimensional diffusion (D2), with E1=202kJmol -1 , lg(A1/s -1 )=22.1, is followed by an irreversible one of nth-order reaction (Fn) with n=0.51, E2=129kJmol -1 , lg(A2/s -1 )=10.5, and the decomposition of Zn 4 CO 3 (OH) 6 .H 2 O to ZnO is accompanied by the change in particle morphology and particle size

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Gas sensing properties of nanocrystalline metal oxide powders produced by thermal decomposition and mechanochemical processing

    OpenAIRE

    Kersen, Ülo

    2003-01-01

    The objective of this research, was the synthesis of LaFeO3 and SnO2 fine powders for the subsequent preparation of thick film gas sensors. On producing fine metal oxide powders, often it is not possible to ensure separation of the particles during the synthesis, resulting in the formation of highly agglomerated material. In addition, there are often high synthetic costs associated with the powders obtained by these methods. Thermal decomposition and mechanochemical processing methods wer...

  14. 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.

  15. Movement of water drops in a forest fuel layer in the course of its thermal decomposition

    Directory of Open Access Journals (Sweden)

    Volkov Roman S.

    2018-01-01

    Full Text Available In this paper, we conducted an experimental investigation on water droplets gravitating in a layer of typical forest fuel (as illustrated by pine needle litter in the course of its thermal decomposition. We used a high-speed (200 fps video recording system, Tema Automotive software with continuous tracking of a moving object as well as a set of low-inertia (no more than 0.1 second thermocouples. Similar experiments were performed at moderate temperatures (below the onset temperature of forest fuel pyrolysis, i. e. about 300 K. Two approaches were used: continuous tracking of a moving water droplet using high-speed video recording and registration of a droplet path using the readings of thermocouples placed at different levels in a forest fuel layer. We determined the typical depths of an forest fuel layer that water droplets reach with the initial volume of these droplets ranging from 90 to 900 μL. The typical velocities of water droplets were calculated at different depths of the forest fuel layer. We also determined the share of the mass of water spent in an forest fuel layer on evaporation and cooling of the material down to the temperatures below those of thermal decomposition. Finally, we identified the physical processes influencing water droplets moving through the layers of forest fuel heated up to the high temperatures similar to those of thermal decomposition.

  16. Decomposition of palladium acetate and C60 fullerite during thermal evaporation in PVD process

    Directory of Open Access Journals (Sweden)

    Rymarczyk Joanna

    2017-10-01

    Full Text Available The mechanisms of thermal decomposition of evaporated material during Physical Vapor Deposition (PVD process depend on the kind of evaporated material. Such parameters of PVD process as deposition rate, source temperature and deposition time should be carefully selected taking into account the properties of material. Deposited films can span the range of chemical compositions based on the source materials. The nanostructural carbon films in form of palladium nanograins embedded in various carbonaceous matrixes were obtained by thermal evaporation during PVD process from two separated sources containing C60 fullerite and palladium acetate, both in a form of powder. The evaporation was realized by resistive heating of sources under a dynamic vacuum of 10-3 Pa. The influence of decomposition path of evaporated materials on the film structure has been discussed. Prepared C-Pd films were characterized using thermo-gravimetric method, differential thermal analysis, infrared spectroscopy and X-ray diffraction. The influence of decomposition of Pd acetate and fullerite on the final film structure was also shown.

  17. 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.

  18. Solid-phase thermal decomposition of 2,4-dinitroimidazole (2,4-DNI)

    Energy Technology Data Exchange (ETDEWEB)

    Minier, L.; Behrens, R. Jr. [Rome Astronomical Observatory (Italy). Space Physics Research Center; Bulusu, S. [Army Armament Research and Development Command, Dover, NJ (United States). Energetic Materials Div.

    1996-12-31

    The solid-phase thermal decomposition of the insensitive energetic nitroaromatic heterocycle 2,4-dinitroimidazole (2,4-DNI: mp 265--274C) is studied utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) between 200 and 247C. The pyrolysis products have been identified using perdeuterated and {sup 15}N-labeled isotopomers. The products consist of low molecular-weight gases and a thermally stable solid residue. The major gaseous products are NO, CO{sub 2}, CO, N{sub 2}, HNCO and H{sub 2}O. Minor gaseous products are HCN, C{sub 2}N{sub 2}, NO{sub 2}, C{sub 3}H{sub 4}N{sub 2}, C{sub 3}H{sub 3}N{sub 3}O and NH{sub 3}. The elemental formula of the residue is C{sub 2}HN{sub 2}O and FTIR analysis suggests that it is polyurea- and polycarbamate-like in nature. Rates of formation of the gaseous products and their respective quantities have been determined for a typical isothermal decomposition experiment at 235C. The temporal behaviors of the gas formation rates indicate that the overall decomposition is characterized by a sequence of four events; (1) an early decomposition period induced by impurities and water, (2) an induction period where C0{sub 2} and NO are the primary products formed at relatively constant rates, (3) an autoacceleratory period that peaks when the sample is depleted and (4) a final period in which the residue decomposes. Arrhenius parameters for the induction period are E{sub a} = 46.9 {plus_minus} 0.7 kcal/mol and Log(A) = 16.3 {plus_minus} 0.3. Decomposition pathways that are consistent with the data are presented.

  19. Effect of air in the thermal decomposition of 50 mass% hydroxylamine/water.

    Science.gov (United States)

    Cisneros, Lizbeth O; Rogers, William J; Mannan, M S

    2002-11-11

    This paper presents experimental measurements of 50 mass% hydroxylamine (HA)/water thermal decomposition in air and vacuum environments using an automatic pressure tracking adiabatic calorimeter (APTAC). Overall kinetics, onset temperatures, non-condensable pressures, times to maximum rate, heat and pressure rates versus temperature, and mixture vapor pressures for the experiments in vacuum were similar when compared to the corresponding data for HA decomposition in air. Determined was an overall activation energy of 119+/-8 kJ/mol (29+/-2 kcal/mol), which is low compared to 257 kJ/mol (61.3 kcal/mol) required to break the H(2)N-OH bond reported in the literature. The availability of oxygen from air did not affect detected runaway decomposition products, which were H(2), N(2), N(2)O, NO, and NH(3), for samples run in vacuum or with air above the sample. A delta H(rxn) of -117 kJ/mol (28 kcal/mol) was estimated for the HA decomposition reaction under runaway conditions.

  20. 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.

  1. TG-FTIR, DSC and quantum chemical studies of the thermal decomposition of quaternary methylammonium halides

    International Nuclear Information System (INIS)

    Sawicka, Marlena; Storoniak, Piotr; Skurski, Piotr; Blazejowski, Jerzy; Rak, Janusz

    2006-01-01

    The thermal decomposition of quaternary methylammonium halides was studied using thermogravimetry coupled to FTIR (TG-FTIR) and differential scanning calorimetry (DSC) as well as the DFT, MP2 and G2 quantum chemical methods. There is almost perfect agreement between the experimental IR spectra and those predicted at the B3LYP/6-311G(d,p) level: this has demonstrated for the first time that an equimolar mixture of trimethylamine and a methyl halide is produced as a result of decomposition. The experimental enthalpies of dissociation are 153.4, 171.2, and 186.7 kJ/mol for chloride, bromide and iodide, respectively, values that correlate well with the calculated enthalpies of dissociation based on crystal lattice energies and quantum chemical thermodynamic barriers. The experimental activation barriers estimated from the least-squares fit of the F1 kinetic model (first-order process) to thermogravimetric traces - 283, 244 and 204 kJ/mol for chloride, bromide and iodide, respectively - agree very well with theoretically calculated values. The theoretical approach assumed in this work has been shown capable of predicting the relevant characteristics of the thermal decomposition of solids with experimental accuracy

  2. 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.

  3. 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.

  4. Investigation of Ag2O Thermal Decomposition by Terahertz Time-Domain Spectroscopy

    International Nuclear Information System (INIS)

    Hua, Chen; Li, Wang

    2009-01-01

    Application of terahertz time-domain spectroscopy is demonstrated to study the process of Ag 2 O thermal decomposition. In the process of decomposition, the time-resolved signals are characterized by broad oscillations and decreased intensity, and THz pulse essentially contains two broad spectral components: one centered at around 0.35 THz and a band with a maximum at around 0.81 THz shift to 0.71 THz. Optical absorption spectra of different specimens are studied in the frequency range 0.3–1.4 THz and the data are analyzed by the relevant theory of the effective medium approach combined with the Drude–Lorentz model. The analysis suggests that optical properties stem from the Drude term for the metallic phase and the Lorentz term for the insulator phase in the complex system. (fundamental areas of phenomenology(including applications))

  5. Thermal decomposition of lanthanides (III) and yttrium (III) solid complexes from ethyl ene diamine tetraacetic acid

    International Nuclear Information System (INIS)

    Mercadante, A.

    1991-01-01

    Solid state compounds of lanthanides (III) and yttrium derived from ethyl ene diamine tetraacetic acid were prepared from respective basic carbonates, that were neutralized with EDTA stoichiometry quantities. Complexometry with EDTA, thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction have been used in the study of these compounds. The results of complexometry with EDTA as well as TG and DTA curves bed to the stoichiometry of these compounds the following general formula is obeyed: H[Ln(EDTA]. n H 2 O. X-ray powder patterns of these compounds permitted to establish two isomorphous series. The DTA ant TG curves allowed us to study the dehydration process, the thermal stability and thermal decomposition of these compounds. (C.G.C.)

  6. 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.

  7. Kinetics of switch grass pellet thermal decomposition under inert and oxidizing atmospheres.

    Science.gov (United States)

    Chandrasekaran, Sriraam R; Hopke, Philip K

    2012-12-01

    Grass pellets are a renewable resource that have energy content similar to that of wood. However, the higher ash and chlorine content affects combustion. Thermal degradation analysis of a fuel is useful in developing effective combustion. Thermogravimetric analysis (TGA) of the thermal degradation of grass pellets under inert (nitrogen) and oxidizing (air) atmospheres was conducted. Non-isothermal conditions were employed with 4 different heating rates. Kinetic parameters (activation energy and pre-exponential factors) were estimated using the iso-conversional method. Both pyrolysis and oxidative atmospheric thermal degradation exhibited two major loss process: volatilization of cellulose, hemicelluloses and lignin and burning or slow oxidation of the residual char. The activation energy and pre-exponential factors were high for the oxidizing environment. During pyrolysis, major decomposition occurred with 40% to 75% conversion of the mass to gas with an activation energy of 314 kJ/mol. In air the decomposition occurred with 30% to 55% conversion with an activation energy of 556 kJ/mol. There was a substantial effect of heating rate on mass loss and mass loss rate. The TG shifted to higher temperature ranges on increasing the heating rate. In both pyrolyzing and oxidizing conditions, average combustion and devolatilization rates increased. Enhanced combustion takes place with higher activation energy in oxidizing atmosphere compared to the inert atmosphere due to presence of air. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

    Yao, M.; Chen, L.; Rao, G.; Peng, J.; Zou, J.; Zeng, X.

    2013-01-01

    In order to improve the detonation performance of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) explosive, addictive with high heat values were used, and magnesium hydride (MgH 2 ) is one of the candidates. However, it is important to see whether MgH 2 is a safe addictive. In this paper, the thermal and kinetic properties of RDX and mixture of RDX/MgH 2 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 MgH 2 decreases both E and A of RDX, which means that the mixture of RDX/MgH 2 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/MgH 2 were given in this paper which confirmed the change of the decomposition mechanism.

  9. 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.

  10. Thermal degradation kinetics and decomposition mechanism of PBSu nanocomposites with silica-nanotubes and strontium hydroxyapatite nanorods.

    Science.gov (United States)

    Papageorgiou, D G; Roumeli, E; Chrissafis, K; Lioutas, Ch; Triantafyllidis, K; Bikiaris, D; Boccaccini, A R

    2014-03-14

    Novel poly(butylene succinate) (PBSu) nanocomposites containing 5 and 20 wt% mesoporous strontium hydroxyapatite nanorods (SrHNRs) and silica nanotubes (SiNTs) were prepared by melt-mixing. A systematic investigation of the thermal stability and decomposition kinetics of PBSu was performed using pyrolysis-gas chromatography-mass spectroscopy (Py-GC-MS) and thermogravimetry (TG). Thorough studies of evolving decomposition compounds along with the isoconversional and model-fitting analysis of mass loss data led to the proposal of a decomposition mechanism for PBSu. Moreover, the effects of SrHNRs and SiNTs on the thermal stability and decomposition kinetics of PBSu were also examined in detail. The complementary use of these techniques revealed that the incorporation of SiNTs in PBSu does not induce significant effects neither on its thermal stability nor on its decomposition mechanism. In contrast, the addition of SrHNRs resulted in the catalysis of the initial decomposition steps of PBSu and also in modified decomposition mechanisms and activation energies. The evolving gaseous products of PBSu and their evolution pattern in the SiNT nanocomposites were the same as in neat PBSu, while they were slightly modified for the SrHNR nanocomposites, confirming the findings from thermogravimetric analysis.

  11. Experimental and DFT simulation study of a novel felodipine cocrystal: Characterization, dissolving properties and thermal decomposition kinetics.

    Science.gov (United States)

    Yang, Caiqin; Guo, Wei; Lin, Yulong; Lin, Qianqian; Wang, Jiaojiao; Wang, Jing; Zeng, Yanli

    2018-05-30

    In this study, a new cocrystal of felodipine (Fel) and glutaric acid (Glu) with a high dissolution rate was developed using the solvent ultrasonic method. The prepared cocrystal was characterized using X-ray powder diffraction, differential scanning calorimetry, thermogravimetric (TG) analysis, and infrared (IR) spectroscopy. To provide basic information about the optimization of pharmaceutical preparations of Fel-based cocrystals, this work investigated the thermal decomposition kinetics of the Fel-Glu cocrystal through non-isothermal thermogravimetry. Density functional theory (DFT) simulations were also performed on the Fel monomer and the trimolecular cocrystal compound for exploring the mechanisms underlying hydrogen bonding formation and thermal decomposition. Combined results of IR spectroscopy and DFT simulation verified that the Fel-Glu cocrystal formed via the NH⋯OC and CO⋯HO hydrogen bonds between Fel and Glu at the ratio of 1:2. The TG/derivative TG curves indicated that the thermal decomposition of the Fel-Glu cocrystal underwent a two-step process. The apparent activation energy (E a ) and pre-exponential factor (A) of the thermal decomposition for the first stage were 84.90 kJ mol -1 and 7.03 × 10 7  min -1 , respectively. The mechanism underlying thermal decomposition possibly involved nucleation and growth, with the integral mechanism function G(α) of α 3/2 . DFT calculation revealed that the hydrogen bonding between Fel and Glu weakened the terminal methoxyl, methyl, and ethyl groups in the Fel molecule. As a result, these groups were lost along with the Glu molecule in the first thermal decomposition. In conclusion, the formed cocrystal exhibited different thermal decomposition kinetics and showed different E a , A, and shelf life from the intact active pharmaceutical ingredient. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Studies on thermal decomposition behaviors of polypropylene using molecular dynamics simulation

    Science.gov (United States)

    Huang, Jinbao; He, Chao; Tong, Hong; Pan, Guiying

    2017-11-01

    Polypropylene (PP) is one of the main components of waste plastics. In order to understand the mechanism of PP thermal decomposition, the pyrolysis behaviour of PP has been simulated from 300 to 1000 K in periodic boundary conditions by molecular dynamic method, based on AMBER force field. The simulation results show that the pyrolysis process of PP can mostly be divided into three stages: low temperature pyrolysis stage, intermediate temperature stage and high temperature pyrolysis stage. PP pyrolysis is typical of random main-chain scission, and the possible formation mechanism of major pyrolysis products was analyzed.

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

    International Nuclear Information System (INIS)

    Cavaignac, A.L.O.; Lima, R.J.C.; Façanha Filho, P.F.; Moreno, A.J.D.; Freire, P.T.C.

    2016-01-01

    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.

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

    Science.gov (United States)

    Cavaignac, A. L. O.; Lima, R. J. C.; Façanha Filho, P. F.; Moreno, A. J. D.; Freire, P. T. C.

    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.

  15. Numerical Investigation into CO Emission, O Depletion, and Thermal Decomposition in a Reacting Slab

    Directory of Open Access Journals (Sweden)

    O. D. Makinde

    2011-01-01

    Full Text Available The emission of carbon dioxide (CO2 is closely associated with oxygen (O2 depletion, and thermal decomposition in a reacting stockpile of combustible materials like fossil fuels (e.g., coal, oil, and natural gas. Moreover, it is understood that proper assessment of the emission levels provides a crucial reference point for other assessment tools like climate change indicators and mitigation strategies. In this paper, a nonlinear mathematical model for estimating the CO2 emission, O2 depletion, and thermal stability of a reacting slab is presented and tackled numerically using a semi-implicit finite-difference scheme. It is assumed that the slab surface is subjected to a symmetrical convective heat and mass exchange with the ambient. Both numerical and graphical results are presented and discussed quantitatively with respect to various parameters embedded in the problem.

  16. 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.

  17. Study of the Thermal Decomposition of Some Components of Biomass by Desorption Mass Spectrometry

    Science.gov (United States)

    Palianytsia, Borys; Kulik, Tetiana; Dudik, Olesia; Cherniavska, Tetiana; Tonkha, Oksana

    The investigation of thermal transformations of lignin samples have been carried out using temperature programmed desorption mass spectrometry method (TPD-MS). Main stages and products of lignin pyrolysis have been identified. The first stages (Tmax = 230 °C and Tmax = 300 °C) are attributed to thermal transformations of lignin peripheral polysaccharide fragments such as hemicellulose and cellulose respectively. The second stage (Tmax = 335 °C) is associated with desorption of lignin structural elements in the molecular forms as a result of depolymerization processes of polymeric blocks of lignin. The third stage (Tmax = 370 °C) correspond to a deeper decomposition of lignin and characterized by desorption of smaller structural fragments in molecular forms (m/z = 110, pyrocatechol). Pressure-temperature curves of pyrolysis of lignin samples have been analyzed.

  18. A novel precursor in preparation and characterization of nickel oxide nanoparticles via thermal decomposition approach

    International Nuclear Information System (INIS)

    Salavati-Niasari, Masoud; Mir, Noshin; Davar, Fatemeh

    2010-01-01

    In order to raise the need of co-surfactant in the synthesis of NiO nanoparticles, [bis(2-hydroxy-1-naphthaldehydato)nickel(II)] complex was employed as a novel precursor in thermal decomposition process using oleylamine (C 18 H 37 N) as surfactant. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-Vis) spectroscopy. Also the novel precursor thermally was treated in solid state reaction in different temperature, 400, 500, and 600 o C. Synthesized nickel oxide nanoparticles have a cubic phase with average size of 15-20 nm.

  19. Thermodynamics and kinetics of thermal decomposition of dibutylalkyl and dipentylalkyl phosphonate-nitric acid systems

    International Nuclear Information System (INIS)

    Chandran, K.; Brahmananda, C.V.S.; Anthonysamy, S.; Srinivasan, T.G.; Ganesan, V.

    2013-01-01

    Tributyl phosphate (TBP) is used in the reprocessing industry for the separation of uranium and plutonium from the spent nuclear fuels by PUREX process. A variety of dialkylalky/phosphonates were synthesised and their extraction behaviour on actinides was studied in this laboratory. The superior extraction characteristics of phosphonates make them useful for several metal recovery applications in the nuclear fuel cycle. However, higher solubility of phosphonates in aqueous phase as compared to TBP, introduces higher chances of the formation of thermally active 'red oil' like substances during the evaporation of aqueous streams. Thermal stability of neat and nitric acid solvated homologues of four dibutylalkyl phosphonates namely, dibutylpropyl phosphonate (DBPrP), dibutylbutyl phosphonate (DBBP), dibutylpentyl phosphonate (DBPP), dibutylhexyl phosphonate (DBHeP), and two dipentylalkyl phosphonates viz. dipentylbutyl phosphonate (DPBP), dipentylhexyl phosphonate (DPHeP) were studied. Experiments were conducted using an adiabatic calorimeter in heat-wait-search mode. Various stoichiometry of nitric acid-solvated DBalP and DPalP were prepared by equilibrating the respective organic with 4-15.6 M nitric acid followed by separation. Neat DBalP and DPalP are stable up to the temperature of ∼ 555 K while their acid-solvates decomposed in the temperature range 380-403 K. The results also indicated that the presence of nitric acid accelerated the decomposition of phosphonates. Decomposition of these acid solvated phosphonates is found to be exothermic and follows first order kinetics. The onset temperature, adiabatic temperature rise, pressure rise, decomposition enthalpy and activation energy were found to strongly depend on the nitric acid content of the acid-solvates. The studies also indicate that dibutylalkyl and dipentylalkyl phosphonates are also prone to form 'red oil' like substances under extreme conditions and can lead to run-away reactions

  20. Determination of Kinetic Parameters for the Thermal Decomposition of Parthenium hysterophorus

    Directory of Open Access Journals (Sweden)

    Dhaundiyal Alok

    2018-02-01

    Full Text Available A kinetic study of pyrolysis process of Parthenium hysterophorous is carried out by using thermogravimetric analysis (TGA equipment. The present study investigates the thermal degradation and determination of the kinetic parameters such as activation E and the frequency factor A using model-free methods given by Flynn Wall and Ozawa (FWO, Kissinger-Akahira-Sonuse (KAS and Kissinger, and model-fitting (Coats Redfern. The results derived from thermal decomposition process demarcate decomposition of Parthenium hysterophorous among the three main stages, such as dehydration, active and passive pyrolysis. It is shown through DTG thermograms that the increase in the heating rate caused temperature peaks at maximum weight loss rate to shift towards higher temperature regime. The results are compared with Coats Redfern (Integral method and experimental results have shown that values of kinetic parameters obtained from model-free methods are in good agreement. Whereas the results obtained through Coats Redfern model at different heating rates are not promising, however, the diffusion models provided the good fitting with the experimental data.

  1. 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.

  2. 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.

  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. A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

    International Nuclear Information System (INIS)

    Jiang, Jun; Xu, Tianhao; Li, Yaping; Lei, Xiaodong; Zhang, Hui; Evans, D. G.; Sun, Xiaoming; Duan, Xue

    2014-01-01

    A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about 100 .deg. C and activation process is essentially complete below 145 .deg. C. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature (170 .deg. C) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles

  5. Characterization and antimicrobial activity of silver nanoparticles prepared by a thermal decomposition technique

    Science.gov (United States)

    Tam, Le Thi; Phan, Vu Ngoc; Lan, Hoang; Thuy, Nguyen Thanh; Hien, Tran Minh; Huy, Tran Quang; Quy, Nguyen Van; Chinh, Huynh Dang; Tung, Le Minh; Tuan, Pham Anh; Lam, Vu Dinh; Le, Anh-Tuan

    2013-11-01

    Recently, there has been an increasing need of efficient synthetic protocols using eco-friendly conditions including low costs and green chemicals for production of metal nanoparticles. In this work, silver nanoparticles (silver NPs) with average particle size about 10 nm were synthesized by using a thermal decomposition technique. Unlike the colloidal chemistry method, the thermal decomposition method developed has advantages such as the high crystallinity, single-reaction synthesis, and easy dispersion ability of the synthesized NPs in organic solvents. In a modified synthesis process, we used sodium oleate as a capping agent to modify the surface of silver NPs because the oleate has a C18 tail with a double bond in the middle, therefore, forming a kink which is to be effective for aggregative stability. Importantly, the as-synthesized silver NPs have demonstrated strong antimicrobial effects against various bacteria and fungi strains. Electron microscopic studies reveal physical insights into the interaction and bactericidal mechanism between the prepared silver NPs and tested bacteria in question. The observed excellent antibacterial and antifungal activity of the silver NPs make them ideal for disinfection and biomedicine applications.

  6. Determination of Kinetic Parameters for the Thermal Decomposition of Parthenium hysterophorus

    Science.gov (United States)

    Dhaundiyal, Alok; Singh, Suraj B.; Hanon, Muammel M.; Rawat, Rekha

    2018-02-01

    A kinetic study of pyrolysis process of Parthenium hysterophorous is carried out by using thermogravimetric analysis (TGA) equipment. The present study investigates the thermal degradation and determination of the kinetic parameters such as activation E and the frequency factor A using model-free methods given by Flynn Wall and Ozawa (FWO), Kissinger-Akahira-Sonuse (KAS) and Kissinger, and model-fitting (Coats Redfern). The results derived from thermal decomposition process demarcate decomposition of Parthenium hysterophorous among the three main stages, such as dehydration, active and passive pyrolysis. It is shown through DTG thermograms that the increase in the heating rate caused temperature peaks at maximum weight loss rate to shift towards higher temperature regime. The results are compared with Coats Redfern (Integral method) and experimental results have shown that values of kinetic parameters obtained from model-free methods are in good agreement. Whereas the results obtained through Coats Redfern model at different heating rates are not promising, however, the diffusion models provided the good fitting with the experimental data.

  7. Comparison of CO2 and oxygen DC submerged thermal plasmas for decomposition of carboxylic acid in aqueous solution

    Science.gov (United States)

    Safa, S.; Hekmat-Ardakan, A.; Soucy, G.

    2014-11-01

    The feasibility of the carboxylic acid decomposition with two different direct current (DC) thermal plasma torches was investigated. An oxygen DC submerged thermal plasma torch and a newly designed submerged DC plasma torch operating with a mixture of carbon dioxide and methane (CO2/CH4) were used. Sebacic acid was selected as a representative of pollutants in the most wastewater produced by chemical process industries. The effect of different operational conditions including treatment time, the reactor pressure as well as the role of oxidizing agents such as (H2O2) were investigated on the decomposition rate of sebacic acid. Concentration of sebacic acid was quantified by Ion Chromatography/Mass Spectrometry (IC/MS). The oxygen plasma showed higher decomposition rate in basic medium. Adding H2O2 into aqueous solution enhanced the sebacic acid decomposition rate with the CO2/CH4 plasma up to the same decomposition rate of the oxygen plasma. Increasing the pressure also increased the decomposition rate for both plasmas with an increase twice higher for the CO2/CH4 plasma than that of the oxygen plasma. This work therefore presents the conditions in which these plasmas can provide the same decomposition rate for contaminants in aqueous solution.

  8. Thermal decomposition of precursors and physicochemical characteristics of titania supported vanadia catalysts

    International Nuclear Information System (INIS)

    Nalbandian, Lori; Lemonidou, Angeliki A.

    2004-01-01

    Titania supported vanadia catalysts (2.5, 5, and 11 wt.% V 2 O 5 ) were prepared by a wet impregnation technique and their thermal behavior, morphology as well as redox properties were examined by thermal analysis methods thermogravimetry (TGA), differential scanning calorimetry (DSC), temperature programmed-evolved gas analysis with mass spectroscopy, (EGA-MS), scanning electron microscopy (SEM), and temperature programmed reduction (TPR). The two Eurocat samples EL10V1 and EL10V8 containing 1 and 8 wt.% V 2 O 5 were also characterized using the same techniques. Thermal decomposition of vanadium oxide precursors (ammonium vanadyl oxalate) supported on TiO 2 as evidenced by thermal analysis, occurs in three successive steps, which are influenced by the surrounding atmosphere (oxidative, reductive, and inert). The presence of tower-like vanadia crystals in the sample with the highest vanadia loading (11 wt.% V 2 O 5 ) was identified by SEM. The H 2 -TPR experiments revealed that the reduction temperature is a factor of the vanadia loading and the type of support. Vanadia species supported on Norton titania are more reducible that those supported on Eurocat titania

  9. Thermal decomposition of [Co(en)3][Fe(CN)6]∙ 2H2O: Topotactic dehydration process, valence and spin exchange mechanism elucidation.

    Science.gov (United States)

    Trávníček, Zdeněk; Zbořil, Radek; Matiková-Maľarová, Miroslava; Drahoš, Bohuslav; Cernák, Juraj

    2013-01-01

    The Prussian blue analogues represent well-known and extensively studied group of coordination species which has many remarkable applications due to their ion-exchange, electron transfer or magnetic properties. Among them, Co-Fe Prussian blue analogues have been extensively studied due to the photoinduced magnetization. Surprisingly, their suitability as precursors for solid-state synthesis of magnetic nanoparticles is almost unexplored. In this paper, the mechanism of thermal decomposition of [Co(en)3][Fe(CN)6] ∙∙ 2H2O (1a) is elucidated, including the topotactic dehydration, valence and spins exchange mechanisms suggestion and the formation of a mixture of CoFe2O4-Co3O4 (3:1) as final products of thermal degradation. The course of thermal decomposition of 1a in air atmosphere up to 600°C was monitored by TG/DSC techniques, (57)Fe Mössbauer and IR spectroscopy. As first, the topotactic dehydration of 1a to the hemihydrate [Co(en)3][Fe(CN)6] ∙∙ 1/2H2O (1b) occurred with preserving the single-crystal character as was confirmed by the X-ray diffraction analysis. The consequent thermal decomposition proceeded in further four stages including intermediates varying in valence and spin states of both transition metal ions in their structures, i.e. [Fe(II)(en)2(μ-NC)Co(III)(CN)4], Fe(III)(NH2CH2CH3)2(μ-NC)2Co(II)(CN)3] and Fe(III)[Co(II)(CN)5], which were suggested mainly from (57)Fe Mössbauer, IR spectral and elemental analyses data. Thermal decomposition was completed at 400°C when superparamagnetic phases of CoFe2O4 and Co3O4 in the molar ratio of 3:1 were formed. During further temperature increase (450 and 600°C), the ongoing crystallization process gave a new ferromagnetic phase attributed to the CoFe2O4-Co3O4 nanocomposite particles. Their formation was confirmed by XRD and TEM analyses. In-field (5 K / 5 T) Mössbauer spectrum revealed canting of Fe(III) spin in almost fully inverse spinel structure of CoFe2O4. It has been found that the thermal

  10. Enhanced Thermal Decomposition Properties of CL-20 through Space-Confining in Three-Dimensional Hierarchically Ordered Porous Carbon.

    Science.gov (United States)

    Chen, Jin; He, Simin; Huang, Bing; Wu, Peng; Qiao, Zhiqiang; Wang, Jun; Zhang, Liyuan; Yang, Guangcheng; Huang, Hui

    2017-03-29

    High energy and low signature properties are the future trend of solid propellant development. As a new and promising oxidizer, hexanitrohexaazaisowurtzitane (CL-20) is expected to replace the conventional oxidizer ammonium perchlorate to reach above goals. However, the high pressure exponent of CL-20 hinders its application in solid propellants so that the development of effective catalysts to improve the thermal decomposition properties of CL-20 still remains challenging. Here, 3D hierarchically ordered porous carbon (3D HOPC) is presented as a catalyst for the thermal decomposition of CL-20 via synthesizing a series of nanostructured CL-20/HOPC composites. In these nanocomposites, CL-20 is homogeneously space-confined into the 3D HOPC scaffold as nanocrystals 9.2-26.5 nm in diameter. The effect of the pore textural parameters and surface modification of 3D HOPC as well as CL-20 loading amount on the thermal decomposition of CL-20 is discussed. A significant improvement of the thermal decomposition properties of CL-20 is achieved with remarkable decrease in decomposition peak temperature (from 247.0 to 174.8 °C) and activation energy (from 165.5 to 115.3 kJ/mol). The exceptional performance of 3D HOPC could be attributed to its well-connected 3D hierarchically ordered porous structure, high surface area, and the confined CL-20 nanocrystals. This work clearly demonstrates that 3D HOPC is a superior catalyst for CL-20 thermal decomposition and opens new potential for further applications of CL-20 in solid propellants.

  11. Kinetics of irreversible thermal decomposition of dissociating nitrogen dioxide with nitrogen oxide or oxygen additions

    International Nuclear Information System (INIS)

    Gvozdev, A.A.

    1987-01-01

    The effect of NO or O 2 admixtures on kinetics of the irreversible thermal decomposition of nitrogen dioxide at temperatures 460-520 deg C and pressures 4-7 MPa has been studied. It follows from experimental data that the rate of N 2 O 4 formation reduces with the increase of partial pressure of oxygen or decrease of partial pressure of nitrogen oxide. The same regularity is seen for the rate of nitrogen formation. The rate constants of N 2 O formation in dissociating nitrogen tetroxide with oxygen or nitrogen oxide additions agree satisfactorily with previously published results, obtained in stoichiometric mixtures. The appreciable discrepancy at 520 deg C is bind with considerable degree of nitrogen oxide transformation which constitutes approximately 14%. It is determined that the kinetics of formation of the products of irreversible N 2 O and N 2 decomposition in stoichiometric and non-stoichiometric 2NO 2 ↔ 2NO+O 2 mixtures is described by identical 3NO → N 2 O+NO 2 and N 2 O+NO → N 2 +NO 2 reactions

  12. Thermal decomposition study of Mn doped Fe3O4 nanoparticles

    Science.gov (United States)

    Malek, Tasmira J.; Chaki, S. H.; Tailor, J. P.; Deshpande, M. P.

    2016-05-01

    Fe3O4 is an excellent magnetic material among iron oxides. It has a cubic inverse spinel structure exhibiting distinguished electric and magnetic properties. In this paper the authors report the synthesis of Mn doped Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its thermal characterization. Ferric chloride hexa-hydrate (FeCl3•6H2O), manganese chloride tetra-hydrate (MnCl2•4H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the as-synthesized Mn doped Fe3O4 nanoparticles were determined by energy dispersive analysis of X-rays (EDAX) technique. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out on the Mn doped Fe3O4 nanoparticles in the temperature range of ambient to 1124 K. The thermo-curves revealed that the particles decompose by four steps. The kinetic parameters were evaluated using non-mechanistic equations for the thermal decomposition.

  13. Direct Iron Coating onto Nd-Fe-B Powder by Thermal Decomposition of Iron Pentacarbonyl

    International Nuclear Information System (INIS)

    Yamamuro, S; Okano, M; Tanaka, T; Sumiyama, K; Nozawa, N; Nishiuchi, T; Hirosawa, S; Ohkubo, T

    2011-01-01

    Iron-coated Nd-Fe-B composite powder was prepared by thermal decomposition of iron pentacarbonyl in an inert organic solvent in the presence of alkylamine. Though this method is based on a modified solution-phase process to synthesize highly size-controlled iron nanoparticles, it is in turn featured by a suppressed formation of iron nanoparticles to achieve an efficient iron coating solely onto the surfaces of rare-earth magnet powder. The Nd-Fe-B magnetic powder was successfully coated by iron shells whose thicknesses were of the order of submicrometer to micrometer, being tuneable by the amount of initially loaded iron pentacarbonyl in a reaction flask. The amount of the coated iron reached to more than 10 wt.% of the initial Nd-Fe-B magnetic powder, which is practically sufficient to fabricate Nd-Fe-B/α-Fe nanocomposite permanent magnets.

  14. Thermal decomposition of ammonium uranous fluoride to anhydrous uranium tetrafluoride in freon - 12 atmosphere

    International Nuclear Information System (INIS)

    Farah, M.Y.; El-Fekey, S.A.; Rofail, N.H.

    1978-01-01

    A systematic study on the thermal decomposition of the double salt has been carried out. A range of temperature, duration, thickness of layers during heating and flow rate of gas were investigated and the physico-chemical properties of the resulting uranium tetrafluoride determined. The chemical analysis included the determination of U 4 , UO 2 formed, UF 4 assay and UO 2 F 2 formed. The X-ray analysis confirmed the formation of anhydrous uranium tetrafluoride after heating of 0.3-cm thick ammonium uranous fluoride layer at 350 0 C while passing 0.05 litre min -1 Freon-12 for four hours. Emission spectrographic analysis confirmed nuclear purity of the final product

  15. Analysis of ZDDP Content and Thermal Decomposition in Motor Oils Using NAA and NMR

    Science.gov (United States)

    Ferguson, S.; Johnson, J.; Gonzales, D.; Hobbs, C.; Allen, C.; Williams, S.

    Zinc dialkyldithiophosphates (ZDDPs) are one of the most common anti-wear additives present in commercially-available motor oils. The ZDDP concentrations of motor oils are most commonly determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). As part of an undergraduate research project, we have determined the Zn concentrations of eight commercially-available motor oils and one oil additive using neutron activation analysis (NAA), which has potential for greater accuracy and less sensitivity to matrix effects as compared to ICP-AES. The 31P nuclear magnetic resonance (31P-NMR) spectra were also obtained for several oil additive samples which have been heated to various temperatures in order to study the thermal decomposition of ZDDPs.

  16. Mass spectrometric investigation into thermal decomposition of double hafnium and ammonium sulfate

    International Nuclear Information System (INIS)

    Fedoryako, L.I.; Sheka, I.A.; Vykhrestyuk, N.I.; Brodskij, E.S.

    1983-01-01

    The method of pyrolytic mass spectrometry has been used to investigate thermal decomposition doUble hafnium ammonium sulfate of the (Nr 4 ) 4 Hf(SO 4 ) 4 X4H 2 O composition during heating from 20 to 800 deg. In volatile destruction products the following ions are found: H 2 O + , NH 3 + , SO + , SO 2 + , O 2 + , H 2 S + , N 2 + , SO 3 + ion is practically absent. Removal of crystallization water occurs in the 85-285 deg range, that of ammonium and sulfur oxides - at 300-775 deg. Higher than 300 deg the ratios of intensities of peaks of SO 2 + :SO + :O 2 + ions do not exceed those standard for SO 2 , which proves a deeper destruction of sUlfUr dioxide under given conditions

  17. Controlled synthesis and phase characterization of Fe-based nanoparticles obtained by thermal decomposition

    International Nuclear Information System (INIS)

    Simeonidis, K.; Mourdikoudis, S.; Moulla, M.; Tsiaoussis, I.; Martinez-Boubeta, C.; Angelakeris, M.; Dendrinou-Samara, C.; Kalogirou, O.

    2007-01-01

    Iron oxide nanoparticles were synthesized by the thermal decomposition of Fe(acac) 3 and Fe(CO) 5 . Three different homogeneous procedures were used for the controlled synthesis of Fe 3 O 4 , γ-Fe 2 O 3 and Fe 3 O 4 /γ-Fe 2 O 3 mixture nanocrystals. A combination of characterization techniques was used in order to distinguish these oxides. The controllable size, the narrow distribution and the rhombic self-assembly of the nanoparticles were revealed by the high-resolution transmission electron microscopy images and the X-ray powder diffraction results. For the quantitative analysis of the samples manganometry was used. Preliminary magnetic measurements indicated the size and composition dependence of saturation magnetization, a superparamagnetic behavior of the samples and some ferromagnetic features

  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. Reaction mechanism of initial dehydration of zirconium oxide chloride octahydrate in its thermal decomposition

    International Nuclear Information System (INIS)

    Kikuchi, Masae

    1974-01-01

    Mechanism of initial dehydration of ZrOCl 2 .8H 2 O was investigated by isothermal heating and X-ray diffraction studies. In the range of 50 0 C to 66.5 0 C, two molecules of three-coordinated lattice water are lost in the first step of dehydration and subsequently one molecule of four-coordinated lattice water is lost. After the loss of three molecules of lattice water, the rate of thermal decomposition become slow and the crystal structure changes. It seems that above 66.5 0 C, both dehydration and chemical reaction which produces HCl presumably occur competitively. Activation energy of the initial dehydration is estimated to be 12.9 kcal-mol. (author)

  20. 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.)

  1. Controlled synthesis and phase characterization of Fe-based nanoparticles obtained by thermal decomposition

    Science.gov (United States)

    Simeonidis, K.; Mourdikoudis, S.; Moulla, M.; Tsiaoussis, I.; Martinez-Boubeta, C.; Angelakeris, M.; Dendrinou-Samara, C.; Kalogirou, O.

    2007-09-01

    Iron oxide nanoparticles were synthesized by the thermal decomposition of Fe(acac) 3 and Fe(CO) 5. Three different homogeneous procedures were used for the controlled synthesis of Fe 3O 4, γ-Fe 2O 3 and Fe 3O 4/γ-Fe 2O 3 mixture nanocrystals. A combination of characterization techniques was used in order to distinguish these oxides. The controllable size, the narrow distribution and the rhombic self-assembly of the nanoparticles were revealed by the high-resolution transmission electron microscopy images and the X-ray powder diffraction results. For the quantitative analysis of the samples manganometry was used. Preliminary magnetic measurements indicated the size and composition dependence of saturation magnetization, a superparamagnetic behavior of the samples and some ferromagnetic features.

  2. 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.

  3. Thermal decomposition study of monovarietal extra virgin olive oil by simultaneous thermogravimetry/differential scanning calorimetry: relation with chemical composition.

    Science.gov (United States)

    Vecchio, Stefano; Cerretani, Lorenzo; Bendini, Alessandra; Chiavaro, Emma

    2009-06-10

    Thermal decomposition of 12 monovarietal extra virgin olive oils from different geographical origins (eight from Italy, two from Spain, and the others from Tunisia) was evaluated by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses. All extra virgin olive oils showed a complex multistep decomposition pattern with the first step that exhibited a quite different profile among samples. Thermal properties of the two peaks obtained by the deconvolution of the first step of decomposition by DSC were related to the chemical composition of the samples (triacylglycerols, fatty acids, total phenols and antioxidant activity). Onset temperatures of the thermal decomposition transition and T(p) values of both deconvoluted peaks as well as the sum of enthalpy were found to exhibit statistically significant correlations with chemical components of the samples, in particular palmitic and oleic acids and related triacylglycerols. Activation energy values of the second deconvoluted peak obtained by the application of kinetic procedure to the first step of decomposition were also found to be highly statistically correlated to the chemical composition, and a stability scale among samples was proposed on the basis of its values.

  4. 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.

  5. 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.

  6. 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

  7. A study of the thermal decomposition of iron(II) and iron(III) rubidium oxalates using the Moessbauer effect

    International Nuclear Information System (INIS)

    Ladriere, J.

    1992-01-01

    The thermal decompositions of Rb 3 Fe(ox) 3 4 H 2 O have been studied using Moessbauer spectroscopy and thermal analysis methods (TGA, DSC). It is shown that after dehydration, the ferric complex is reduced into a ferrous compound, with a large quadrupole splitting (3.84 mm/s), which corresponds to the anhydrous form of Rb 2 Fe(ox) 2 6 H 2 O. (orig.)

  8. Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition

    Czech Academy of Sciences Publication Activity Database

    Asadi, M.; Asadi, Z.; Savaripoor, N.; Dušek, Michal; Eigner, Václav; Shorkaei, M.R.; Sedaghat, M.

    2015-01-01

    Roč. 136, Feb (2015), 625-634 ISSN 1386-1425 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : Oxovanadium(IV) complexes * Schiff base * Kinetics of thermal decomposition * Electrochemistry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.653, year: 2015

  9. Studies on the thermal decomposition kinetics of LiPF6 and LiBC4O8

    Indian Academy of Sciences (India)

    WINTEC

    Electrolyte which plays a crucial role in ion transport is one of the most important components of lithium- ... thermodynamic performances are absent, especially about the thermal decomposition kinetics. In these ... and obtained many useful thermodynamic and kinetic information that can help us to understand their.

  10. 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

  11. Study on the characterization and thermal decomposition of uranium compounds by thermogravimetry (TG) and differential scanning calorimetry (DSC)

    International Nuclear Information System (INIS)

    Dantas, J.M.; Abrao, A.

    1981-04-01

    A contribution to the characterization of several uranium compounds obtained at the IPEN' Uranium Pilot Plant is given. Particularly, samples of ammonium diuranate (ADU) and uranium oxides were studied. The main objective was to know the stoichiometry of the ADU and the oxides resulting from its thermal transformation. ADU samples were prepared by batchwise precipitation, stationary dewatering into stove and batchwise thermal decomposition, or, alternatively, continuous precipitation, continuous filtration, continuous drying and continuous thermal decomposition inside a temperature gradient electrical furnace. All ADU were precipitated using NH 3 gas from uranul sulfate or uranyl nitrate solutions. The thermal decomposition of ADU and uranium oxides were studied in an air atmosphere by thermogravimetry (TG) and differential scanning calorimetry (DSC). Any correlation between the parameters of precipitation, drying, calcination and the hystory of the obtaintion of the several uraniumm compounds and their initial and final composition was looked for. Heating program was established to have the U 3 O 8 oxide as the final product. Intermediary phases were tentatively identified. Temperatures at which occurred the absorption water elimination, crystallization water elimination, evolution or oxidation of NH 3 , decomposition of NO -3 ion and oxygen evolution and the exo- and endothermic process for each sample were identified. (Author) [pt

  12. Mechanism of thermal decomposition of a pesticide for safety concerns: Case of Mancozeb

    Energy Technology Data Exchange (ETDEWEB)

    Giroud, N. [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France); TREDI, Service Recherche, Technopole de Nancy-Brabois, 9, avenue de la foret de Haye, 54505 Vandoeuvre-les-Nancy (France); Dorge, S., E-mail: sophie.dorge@uha.fr [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France); Trouve, G. [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France)

    2010-12-15

    Thermal decomposition under both air and inert atmospheres of a commercial Mancozeb product was investigated through thermogravimetric analysis and laboratory scale thermal treatment from 20 deg. C to 950 deg. C, with analysis of gaseous and solid products. The aim of this study is the understanding of the thermal degradation mechanisms of a pesticide under different atmospheres and the chemical identification of the solid and gaseous pollutants which can be emitted during warehouse fires and which can constitute a threat for health and environment. Pyrolysis of Mancozeb takes place between 20 deg. C and 950 deg. C and lead essentially to CS{sub 2} and H{sub 2}S emissions with formation at 950 deg. C of MnS and ZnS. Thermal oxidation of Mancozeb under air occurs between 150 deg. C and 950 deg. C with formation of CO, CO{sub 2} and sulphur gases (CS{sub 2} and SO{sub 2}). The first step (155-226 deg. C) is the loss of CS{sub 2} and the formation of ethylene thiourea, ZnS and MnS. The metallic sulphides are oxidized in ZnO and MnSO{sub 4} between 226 deg. C and 650 deg. C (steps 2 and 3). MnSO{sub 4} is then oxidized in Mn{sub 3}O{sub 4} during the last step (step 4) between 650 deg. C and 950 deg. C. At 950 deg. C, carbon recovery is close to 95%. Sulphur recovery is close to 98% with an equal partition between SO{sub 2} and CS{sub 2}.

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

    Energy Technology Data Exchange (ETDEWEB)

    Grivel, J.-C., E-mail: jean@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK - 4000 Roskilde (Denmark); Zhao, Y.; Suarez Guevara, M.J. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK - 4000 Roskilde (Denmark); Watenphul, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Institute of Mineralogy and Petrography, University of Hamburg, Grindelallee 48, 20146 Hamburg (Germany)

    2015-07-20

    Highlights: • The thermal decomposition of Lathanum valerate and caproate has been studied in Ar. • The compounds melt prior to decomposition. • Gas release in the molten state results in irregular mass loss. • CO{sub 2} and symmetrical ketones are the main evolving gas species. - Abstract: The decomposition of La-valerate (La(C{sub 4}H{sub 9}CO{sub 2}){sub 3}·xH{sub 2}O (x ≈ 0.45)) and La-caproate (La(C{sub 5}H{sub 11}CO{sub 2}){sub 3}·xH{sub 2}O (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 sources as well as hot-stage microscopy, it was found that both compounds melt prior to decomposition and that the main decomposition stage from the molten, anhydrous state leads to the formation of La-dioxycarbonate (La{sub 2}O{sub 2}CO{sub 3}) via an unstable intermediate product and release of symmetrical ketones. Final decomposition to La{sub 2}O{sub 3} takes place with release of CO{sub 2}.

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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

    2018-03-01

    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.

  19. Kinetics of thermal decomposition of titanium hydride powder using in situ high-temperature X-ray diffraction (HTXRD

    Directory of Open Access Journals (Sweden)

    Hugo Ricardo Zschommler Sandim

    2005-09-01

    Full Text Available The thermal decomposition of titanium hydride powder (delta-phase to titanium (alpha-phase was investigated by means of thermogravimetric analysis (TGA and high-temperature X-ray diffraction (HTXRD in high vacuum. The delta-to-alpha phase transformation was followed in situ by HTXRD at temperatures varying from room temperature up to 1000 °C. The transformation was also analyzed as a function of time at isothermal conditions from 450 to 650 °C. The results of TGA show that the decomposition of the titanium hydride becomes significant at about 450 °C. Above 500 °C the decomposition is completed in times shorter than 50 minutes. The apparent activation energy for hydrogen desorption was found to be 63 ± 6 kJ.mol-1.

  20. In situ ESEM study of the thermal decomposition of chrysotile asbestos in view of safe recycling of the transformation product

    International Nuclear Information System (INIS)

    Gualtieri, Alessandro F.; Gualtieri, Magdalena Lassinantti; Tonelli, Massimo

    2008-01-01

    The thermal transformation of asbestos into non-hazardous crystalline phases and their recycling is a promising solution for the 'asbestos problem'. The most common asbestos-containing industrial material produced worldwide is cement-asbestos. Knowledge of the kinetics of thermal transformation of asbestos fibers in cement-asbestos is of paramount importance for the optimization of the firing process at industrial scale. Here, environmental scanning electron microscopy (ESEM) was used for the first time to follow in situ the thermal transformation of chrysotile fibers present in cement-asbestos. It was found that the reaction kinetics of thermal transformation of chrysotile was highly slowed down in the presence of water vapor in the experimental chamber with respect to He. This was explained by chemisorbed water on the surface of the fibers which affected the dehydroxylation reaction and consequently the recrystallization into Mg-silicates. In the attempt to investigate alternative and faster firing routes for the decomposition of asbestos, a low melting glass was mixed with cement-asbestos and studied in situ to assess to which extent the decomposition of asbestos is favored. It was found that the addition of a low melting glass to cement-asbestos greatly improved the decomposition reaction and decreased the transformation temperatures

  1. Thermal behavior and decomposition kinetics of rifampicin polymorphs under isothermal and non-isothermal conditions

    Directory of Open Access Journals (Sweden)

    Ricardo Alves

    2010-06-01

    Full Text Available The thermal behavior of two polymorphic forms of rifampicin was studied by DSC and TG/DTG. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form, the DSC curve showed no fusion for this species and the thermal decomposition process occurred around 245 ºC. The DSC curve of polymorph II showed two consecutive events, an endothermic event (Tpeak = 193.9 ºC and one exothermic event (Tpeak = 209.4 ºC, due to a melting process followed by recrystallization, which was attributed to the conversion of form II to form I. Isothermal and non-isothermal thermogravimetric methods were used to determine the kinetic parameters of the thermal decomposition process. For non-isothermal experiments, the activation energy (Ea was derived from the plot of Log β vs 1/T, yielding values for polymorph form I and II of 154 and 123 kJ mol-1, respectively. In the isothermal experiments, the Ea was obtained from the plot of lnt vs 1/T at a constant conversion level. The mean values found for form I and form II were 137 and 144 kJ mol-1, respectively.O comportamento térmico de duas formas polimórficas da rifampicina foi estudado por DSC e TG/DTG. Os resultados termoanalíticos mostraram claramente as diferenças entre as duas formas cristalinas. O polimorfo I é a forma mais estável termicamente, a curva DSC não mostrou a fusão dessa espécie e o processo de decomposição térmica ocorreu próximo a 245 ºC. A curva DSC do Polimorfo II apresentou dois eventos consecutivos, um endotérmico (Tpico = 193,9 ºC e outro exotérmico (Tpico = 209,4 ºC, devido à fusão seguida de recristalização, a qual foi atribuída à conversão da forma II à forma I. Métodos termogravimétricos isotérmicos e não-isotérmicos foram empregados para determinar os parâmetros cinéticos do processo de decomposição térmica. Para experimentos não-isotérmicos, a energia de ativação (Ea foi

  2. 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.

  3. Pressurized thermal and hydrothermal decomposition of algae, wood chip residue, and grape marc: A comparative study

    International Nuclear Information System (INIS)

    Subagyono, Dirgarini J.N.; Marshall, Marc; Jackson, W. Roy; Chaffee, Alan L.

    2015-01-01

    Pressurized thermal decomposition of two marine algae, Pinus radiata chip residue and grape marc using high temperature, high pressure reactions has been studied. The yields and composition of the products obtained from liquefactions under CO of a mixture of biomass and H 2 O (with or without catalyst) were compared with products from liquefaction of dry biomass under N 2 , at different temperatures, gas pressures and for CO runs, water to biomass ratios. Thermochemical reactions of algae produced significantly higher dichloromethane solubles and generally higher product yields to oil and asphaltene than Pinus radiata and grape marc under the reaction conditions used. Furthermore, the biofuels derived from algae contained significant concentrations of aliphatic hydrocarbons as opposed to those from radiata pine and grape marc which were richer in aromatic compounds. The possibility of air transport fuel production from algae thus appears to have considerable advantages over that from radiata pine and grape marc. - Highlights: • Liquefaction of algae gave more oil than that of Pinus radiata and grape marc. • Reactions under CO/H 2 O produced higher yields of oil than N 2 . • Water to biomass ratio had little effect on the yields. • Bio-oil from algae contained substantial amounts of aliphatic hydrocarbons. • Pinus radiata oil was low in N but high in O

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-03

    We present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting properties. Monodisperse superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of three different iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) in organic solvents 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. 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 is also critical for establishing magnetic properties. As an example, we show the importance of obtaining the required iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled.

  5. Thermochemical cycles for energy storage: Thermal decomposition of ZnCO sub 4 systems

    Energy Technology Data Exchange (ETDEWEB)

    Wentworth, W.E. (Houston Univ., TX (United States))

    1992-04-01

    The overall objective of our research has been to develop thermochemical cycles that can be used for energy storage. A specific cycle involving ammonium hydrogen sulfate (NH{sub 4}HSO{sub 4}) has been proposed. Each reaction in the proposed cycle has been examined experimentally. Emphasis has been placed on the basic chemistry of these reactions. In the concluding phase of this research, reported herein, we have shown that when NH{sub 4}HSO{sub 4} is mixed with ZnO and decomposed, the resulting products can be released stepwise (H{sub 2}A{sub (g)} at {approximately}163{degrees}C, NH{sub 3(g)} at 365--418{degrees}C, and a mixture of SO{sub 2(g)} and SO{sub 3(g)} at {approximately}900{degrees}C) and separated by controlling the reaction temperature. Side reactions do not appear to be significant and the respective yields are high as would be required for the successful use of this energy storage reaction in the proposed cycle. Thermodynamic, kinetic, and other reaction parameters have been measured for the various steps of the reaction. Finally we have completed a detailed investigation of one particular reaction: the thermal decomposition of zinc sulfate (ZnSO{sub 4}). We have demonstrated that this reaction can be accelerated and the temperature required reduced by the addition of excess ZnO, V{sub 2}A{sub 5} and possibly other metal oxides.

  6. Thermal decomposition study of uranyl nitrate and cerium hydroxide in a spray dryer

    International Nuclear Information System (INIS)

    Silva Wildhagen, G.R. da.

    1993-05-01

    A study, in a spray dryer system based on drying and thermal decomposition of uranyl nitrate solutions aiming the production of uranium trioxide adequate for the use in posterior steps of reduction and hydro fluorination in nuclear fuel cycle; and cerium hydroxide suspensions for the production of cerium oxide with high surface area is presented. Thus, the project and construction of a countercurrent spray dryer was elaborated for capacity of 10 Kg U O 3 /h and 3,5 k Ce O 2 /h. The methodology used in these experiments consisted in the analysis of several parameters (concentration and flow rate of the feed, atomization pressure and inlet temperature of the dryer) over the physical and chemical properties of the products. Using the obtained results, with the help of a mathematical model, it was developed the project of a continuous pilot unity for the production of uranium trioxide or cerium oxide, with capacity of 20 Kg U O 3 /h or 10 Kg Ce O 2 /h, respectively. (author)

  7. 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.

  8. 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%.

  9. 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.

  10. The preparation of cerium oxide by thermal decomposition and the determination of the particle characteristics

    International Nuclear Information System (INIS)

    Horsley, S.; Towner, J.M.; Waldron, M.B.

    1975-01-01

    Cerium IV oxides were prepared by selective thermal treatment of Cerium III oxalate. The ''activity'' of these powders was assessed by several techniques including gas adsorption, X-ray line broadening, differential scanning calorimetry, electron microscopy, and heterogeneous catalysis studies. The compaction and the initial sintering stages of fine powders are known to be affected by the absolute particle size, the surface chemistry and the structure of the material. The general concept of ''activity'' has been used to describe the effects of these properties on the behavior of powder compacts. In this work the degree of interrelation between several possible causes of ''activity'' are explored. The variation in the amount of energy stored in the surface and the bulk of differently prepared powders is considered in relation to the probable mode of solid state decomposition of the oxalate salt. The possibility of measuring the release of such ''strain'' energies is discussed. The influence of lattice disorder on the heterogeneous catalysis properties of the powders is also considered

  11. Gaseous phase benzene decomposition by non-thermal plasma coupled with nano titania catalyst

    International Nuclear Information System (INIS)

    Zhu, T.; Li, J.; Jin, Y. Q.; Liang, Y. H.; Ma, G. D.

    2009-01-01

    Synergistic effect of atmospheric non-thermal plasma generated by dielectric barrier discharge and nano titania photo catalyst for benzene decomposition was tested. The paper indicated the effect of photo catalyst on removal efficiency of benzene, the compare of photo catalyst characteristic in different high temperatures by heat treatment, analysis of by-products. The results showed that the effect of degradation was visible by added photo catalyst in the plasma reactor. When concentration of benzene was 600 mg/m 3 and electric field strength was 10 kV/cm, the removal efficiency of benzene was increased up to 81 % without photo catalyst. At the same condition, the removal efficiency was increased to 15 % higher with photo catalyst. Nano titania crystal was anatase crystal in 450 d eg C heat treatment which is best for benzene removal. The plasma reactor packed with photo catalyst shows a better selectivity of carbon dioxide than that without photo catalyst. By-products are mostly carbon dioxide, water and a small quantity of carbon monoxide

  12. Thermal decomposition of the amino acids glycine, cysteine, aspartic acid, asparagine, glutamic acid, glutamine, arginine and histidine.

    Science.gov (United States)

    Weiss, Ingrid M; Muth, Christina; Drumm, Robert; Kirchner, Helmut O K

    2018-01-01

    The pathways of thermal instability of amino acids have been unknown. New mass spectrometric data allow unequivocal quantitative identification of the decomposition products. Calorimetry, thermogravimetry and mass spectrometry were used to follow the thermal decomposition of the eight amino acids G, C, D, N, E, Q, R and H between 185 °C and 280 °C. Endothermic heats of decomposition between 72 and 151 kJ/mol are needed to form 12 to 70% volatile products. This process is neither melting nor sublimation. With exception of cysteine they emit mainly H 2 O, some NH 3 and no CO 2 . Cysteine produces CO 2 and little else. The reactions are described by polynomials, AA→ a NH 3 + b H 2 O+ c CO 2 + d H 2 S+ e residue, with integer or half integer coefficients. The solid monomolecular residues are rich in peptide bonds. Eight of the 20 standard amino acids decompose at well-defined, characteristic temperatures, in contrast to commonly accepted knowledge. Products of decomposition are simple. The novel quantitative results emphasize the impact of water and cyclic condensates with peptide bonds and put constraints on hypotheses of the origin, state and stability of amino acids in the range between 200 °C and 300 °C.

  13. Kinetic analysis of the thermal decomposition of Li4Ti5O12 pellets

    Directory of Open Access Journals (Sweden)

    Hugo A. Mosqueda

    2011-12-01

    Full Text Available A single dynamic kinetic analysis, describing the surface decomposition of Li4Ti5O12 pellets, has been performed. Samples were analyzed by X-ray diffraction and scanning electron microscopy. The analyses were performed between 1000 and 1100°C and different times, perceiving the Li4Ti5O12 decomposition to Li2Ti3O7, with a loss of lithium. As expected, more rapid decomposition behaviour was found at higher temperatures. Finally, the activation energy for this decomposition of Li4Ti5O12 to Li2Ti3O7 was estimated to be equal to 383 kJ/mol.

  14. 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

  15. 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.

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

    Science.gov (United States)

    Tan, Linghua; Xu, Jianhua; Li, Shiying; Li, Dongnan; Dai, Yuming; Kou, Bo; Chen, Yu

    2017-01-01

    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. PMID:28772844

  17. 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.

  18. 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.

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

    International Nuclear Information System (INIS)

    Eslami, Abbas; Juibari, Nafise Modanlou; Hosseini, Seyed Ghorban

    2016-01-01

    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 2+ and Cr 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.

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

    Science.gov (United States)

    Tan, Linghua; Xu, Jianhua; Li, Shiying; Li, Dongnan; Dai, Yuming; Kou, Bo; Chen, Yu

    2017-05-02

    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.

  1. Optimum Conditions for Effective Decomposition of Toluene as VOC Gas by Pilot-Scale Regenerative Thermal Oxidizer

    OpenAIRE

    S. Iijima; K. Nakayama; D. Kuchar; M. Kubota; H. Matsuda

    2008-01-01

    Regenerative Thermal Oxidizer (RTO) is one of the best solutions for removal of Volatile Organic Compounds (VOC) from industrial processes. In the RTO, VOC in a raw gas are usually decomposed at 950-1300 K and the combustion heat of VOC is recovered by regenerative heat exchangers charged with ceramic honeycombs. The optimization of the treatment of VOC leads to the reduction of fuel addition to VOC decomposition, the minimization of CO2 emission and operating cost as wel...

  2. A study of the solid-phase thermal decomposition of NTO using simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS)

    Energy Technology Data Exchange (ETDEWEB)

    Minier, L.; Behrens, R. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility; Burkey, T.J. [Univ. of Memphis, TN (United States). Chemistry Dept.

    1997-01-01

    The solid phase thermal reaction chemistry of NTO between 190 and 250 C is presently being evaluated by utilizing STMBMS, a technique that enables the authors to measure the vapor pressure of NTO and to explore the reaction mechanisms and chemical kinetics associated with the NTO thermal decomposition process. The vapor pressure of NTO is expressed as Log{sub 10} p(torr) = 12.5137 + 6,296.553(1/t{sub k}) and the {Delta}H{sub subl} = 28.71 {+-} 0.07 kcal/mol (120.01 {+-} 0.29 kJ/mol). The pyrolysis of NTO results in the formation of gaseous products and a condensed-phase residue. The identity of the major gaseous products and their origin from within the NTO molecules are determined based on the results from pyrolysis of NTO, NTO-3-{sup 13}C, NTO-1,2-{sup 15}N{sub 2} and NTO-{sup 2}H{sub 2}. Identification of the products show the major gaseous products to be N{sub 2}, CO{sub 2}, NO, HNCO, H{sub 2}O and some N{sub 2}O, CO, HCN and NH{sub 3}. The N{sub 2} is mostly derived from the N-1 and N-2 positions with some being from the N-4 and N-1 or N-2 positions. The CO{sub 2} is derived from both carbons in the NTO molecule in comparable amounts. The residue has an elemental formula of C{sub 2.1}H{sub .26}N{sub 2.9}O and FTIR analysis suggests that the residue is polyurea- and polycarbamate-like in nature. The temporal behaviors of the rates of formation of the gaseous products indicate that the overall thermal decomposition of NTO in the temperature range evaluated involves four major processes: (1) NTO sublimation; (2) an apparent solid-solid phase transition between 190 and 195 C; (3) a decomposition regime induced by the presence of exogenous H{sub 2}O at the onset of decomposition; and (4) a decomposition regime that occurs at the onset of decomposition and continues until the depletion of NTO. Decomposition pathways that are consistent with the data are presented.

  3. 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.

  4. Thermal decomposition and X-ray diffraction of sulphate efflorescent minerals from El Jaroso Ravine, Sierra Almagrera, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Frost, Ray L. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia)]. E-mail: r.frost@qut.edu.au; Wain, Daria [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Martens, Wayde N. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Locke, Ashley C. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Martinez-Frias, Jesus [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Cristalografia y Mineralogia, Unidad Asociada al Centro de Astrobiologia INTA-CSIC, Universidad de Valladolid, 47006 Valladolid (Spain); Rull, Fernando [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Cristalografia y Mineralogia, Unidad Asociada al Centro de Astrobiologia INTA-CSIC, Universidad de Valladolid, 47006 Valladolid (Spain)

    2007-08-25

    Two evaporite minerals from the El Jaroso Ravine, Spain have been analysed by thermogravimetry coupled with an evolved gas mass spectrometer. X-ray diffraction results proved the evaporite minerals were a mixture of sulphates including the minerals magnesiocopiapite, coquimbite and possibly alunogen. Thermal decomposition of the unoxidised samples showed steps at 52, 99 and 143 deg. C confirmed by mass spectrometric results and attributed to adsorbed water, interstitial water and chemically bonded water. This evaporite mineral rock showed two higher temperature decomposition steps at 555 and 599 deg. C with mass losses of 19.6 and 7.8%. Slightly different temperatures for the thermal decomposition of the oxadada sample were observed at 52, 64.5 and 100 deg. C. Two higher temperature mass loss steps at 560.5 and 651 deg. C were observed for the oxidised sample. By comparison of the thermal analysis patterns of halotrichite and jarosite it can be shown that the El Jaroso samples are mineral sulphates and not halotrichite or jarosite.

  5. 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 (Cr 2 O 3 ) and magnesiochromite (MgCr 2 O 4 ) 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.

  6. Synthesis of water-dispersible silver nanoparticles by thermal decomposition of water-soluble silver oxalate precursors.

    Science.gov (United States)

    Togashi, Takanari; Saito, Kota; Matsuda, Yukiko; Sato, Ibuki; Kon, Hiroki; Uruma, Keirei; Ishizaki, Manabu; Kanaizuka, Katsuhiko; Sakamoto, Masatomi; Ohya, Norimasa; Kurihara, Masato

    2014-08-01

    Silver oxalate, one of the coordination polymer crystals, is a promising synthetic precursor for transformation into Ag nanoparticles without any reducing chemicals via thermal decomposition of the oxalate ions. However, its insoluble nature in solvents has been a great disadvantage, especially for systematic control of crystal growth of the Ag nanoparticles, while such control of inorganic nanoparticles has been generally performed using soluble precursors in homogeneous solutions. In this paper, we document our discovery of water-soluble species from the reaction between the insoluble silver oxalate and N,N-dimethyl-1,3-diaminopropane. The water-soluble species underwent low-temperature thermal decomposition of the oxalate ions at 30 °C with evolution of CO2 to reduce Ag+ to Ag0. Water-dispersible Ag nanoparticles have been successfully synthesized from the water-soluble species in the presence of gelatin via similar thermal decomposition at 100 °C. The gelatin-protected and water-dispersible Ag nanoparticles with a mean diameter of 25.1 nm appeared. In addition, antibacterial activity of the prepared water-dispersible Ag nanoparticles has been preliminarily investigated.

  7. 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.

  8. 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.

  9. Synthesis of zinc sulphide nanoparticles from thermal decomposition of zinc N-ethyl cyclohexyl dithiocarbamate complex

    International Nuclear Information System (INIS)

    Abdullah, Nurul Hidayah; Zainal, Zulkarnain; Silong, Sidik; Tahir, Mohamed Ibrahim Mohamed; Tan, Kar-Ban; Chang, Sook-Keng

    2016-01-01

    Synthesis of nanostructured semiconductor materials from various single source precursors has been massively explored for potential applications in modern technology. Thermal decomposition method has been employed to prepare nanoparticles zinc sulphide from zinc N-ethyl cyclohexyl dithiocarbamate precursor. Effect of heat treatment at different calcination duration on the structural, morphological, compositional and band gap properties of zinc sulphide were investigated. The obtained samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) analysis. XRD showed the precursor was decomposed to hexagonal zinc sulphide after 2–6 h of calcination duration at 400 °C. The sizes of zinc sulphide (ZnS) nanoparticles obtained from TEM analysis were about 6–11 nm. The existence of the hexagonal ZnS phase is not affected by the calcination duration, while only a slight difference in the crystallinity and crystallite size of ZnS is observed from XRD analysis. EDX analyses reveal that the as-prepared ZnS nanoparticles have an approximate composition of Zn and S close to 1:1, giving a possible composition of ZnS. Besides, direct band gap energy of ZnS was found to be around 3.78–3.95 eV. - Highlights: • Zinc N-ethyl cyclohexyl dithiocarbamate was used as single source precursor. • No surfactant was used in the preparation of ZnS nanoparticles. • Pure phase nanostructured ZnS is obtained. • A good stoichiometric sample with an average atomic ratio of Zn:S close to 1:1.

  10. Synthesis of zinc sulphide nanoparticles from thermal decomposition of zinc N-ethyl cyclohexyl dithiocarbamate complex

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Nurul Hidayah [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainal, Zulkarnain, E-mail: zulkar@upm.edu.my [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Silong, Sidik [UiTM Negeri Sembilan, Kampus Kuala Pilah, Pekan Parit Tinggi, 72000 Kuala Pilah, Negeri Sembilan (Malaysia); Tahir, Mohamed Ibrahim Mohamed; Tan, Kar-Ban [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Chang, Sook-Keng [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2016-04-15

    Synthesis of nanostructured semiconductor materials from various single source precursors has been massively explored for potential applications in modern technology. Thermal decomposition method has been employed to prepare nanoparticles zinc sulphide from zinc N-ethyl cyclohexyl dithiocarbamate precursor. Effect of heat treatment at different calcination duration on the structural, morphological, compositional and band gap properties of zinc sulphide were investigated. The obtained samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) analysis. XRD showed the precursor was decomposed to hexagonal zinc sulphide after 2–6 h of calcination duration at 400 °C. The sizes of zinc sulphide (ZnS) nanoparticles obtained from TEM analysis were about 6–11 nm. The existence of the hexagonal ZnS phase is not affected by the calcination duration, while only a slight difference in the crystallinity and crystallite size of ZnS is observed from XRD analysis. EDX analyses reveal that the as-prepared ZnS nanoparticles have an approximate composition of Zn and S close to 1:1, giving a possible composition of ZnS. Besides, direct band gap energy of ZnS was found to be around 3.78–3.95 eV. - Highlights: • Zinc N-ethyl cyclohexyl dithiocarbamate was used as single source precursor. • No surfactant was used in the preparation of ZnS nanoparticles. • Pure phase nanostructured ZnS is obtained. • A good stoichiometric sample with an average atomic ratio of Zn:S close to 1:1.

  11. Effects of defects on thermal decomposition of HMX via ReaxFF molecular dynamics simulations.

    Science.gov (United States)

    Zhou, Ting-Ting; Huang, Feng-Lei

    2011-01-20

    Effects of molecular vacancies on the decomposition mechanisms and reaction dynamics of condensed-phase β-HMX at various temperatures were studied using ReaxFF molecular dynamics simulations. Results show that three primary initial decomposition mechanisms, namely, N-NO(2) bond dissociation, HONO elimination, and concerted ring fission, exist at both high and lower temperatures. The contribution of the three mechanisms to the initial decomposition of HMX is influenced by molecular vacancies, and the effects vary with temperature. At high temperature (2500 K), molecular vacancies remarkably promote N-N bond cleavage and concerted ring breaking but hinder HONO formation. N-N bond dissociation and HONO elimination are two primary competing reaction mechanisms, and the former is dominant in the initial decomposition. Concerted ring breaking of condensed-phase HMX is not favored at high temperature. At lower temperature (1500 K), the most preferential initial decomposition pathway is N-N bond dissociation followed by the formation of NO(3) (O migration), although all three mechanisms are promoted by molecular vacancies. The promotion effect on concerted ring breaking is considerable at lower temperature. Products resulting from concerted ring breaking appear in the defective system but not in the perfect crystal. The mechanism of HONO elimination is less important at lower temperature. We also estimated the reaction rate constant and activation barriers of initial decomposition with different vacancy concentrations. Molecular vacancies accelerate the decomposition of condensed-phase HMX by increasing the reaction rate constant and reducing activation barriers.

  12. Thermal decomposition studies of riot control agent ω-chloroacetophenone (CN) by pyrolysis-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Nigam, Anil K; Suryanarayana, M V S; Gutch, P K; Sharma, Shiv P; Tomar, L N S; Vijayaraghavan, R

    2010-12-15

    Pyrolysis-GC/MS system with on-line micro-furnace was used to make rapid evaluation of ω-chloroacetophenone (CN) decomposition under inert thermal atmospheres. The volatile products evolved during pyrolysis were analyzed by thermal gravimetric analysis (TGA) and Py-GC/MS to obtain specific thermogram and pyrogram. Thermal gravimetric analysis results showed that CN undergoes sublimation at 167°C prior to its decomposition at 229°C. Totally 45 degradation products were identified based on mass spectral library matching with the aid of correlation of the values of boiling point (bp) and retention time. A large number of mono-aromatics and polycyclic aromatic hydrocarbons were observed beyond 600°C. In addition to the aromatic hydrocarbons, oxygenated compounds were also observed during the pyrolysis process. The pyrolysis mechanism was proposed based on the determined pyrolysates and their relative abundance with temperature. The investigation results can provide significant information for understanding the thermal behavior of CN and evaluation of the potential influence of the pyrolysates to living being and the environment. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. 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.

  14. 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).

  15. 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

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

    Directory of Open Access Journals (Sweden)

    Marisa S. Crespi

    1999-02-01

    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.

  17. 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...

  18. Kinetics and Mechanism of the CIO + CIO Reaction: Pressure and Temperature Dependences of the Bimolecular and Termolecular Channels andThermal Decomposition of Chlorine Peroxide, CIOOCI

    Science.gov (United States)

    Nickolaisen, Scott L.; Friedl, Randall R.; Sander, Stanley P.

    1993-01-01

    The kinetics and mechanism of the CIO + CIO reaction and the thermal decomposition of CIOOCI were studied using the flash photolysis/long path ultraviolet absorption technique. Pressure and temperature dependences were determined for the rate coefficients for the bimolecular and termolecular reaction channels, and for the thermal decompositon of CIOOCI.

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

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Among the catalytic study, MnOx/SMF (manganese oxide on sintered metal fibres electrode) shows better performance, probably due to the formation of active oxygen species by in situ decomposition of ozone on the catalyst surface. Water vapour further enhanced the performance due to the in situ ...

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

    Indian Academy of Sciences (India)

    better performance, probably due to the formation of active oxygen species by in situ decomposition of ozone on the catalyst surface. Water vapour further enhanced the performance due to the in situ formation of OH radicals. Keywords. ..... and Industrial Research (CSIR), India for the financial support. References. 1. Monks ...

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

    Science.gov (United States)

    2011-05-03

    estimated from the temperature of the Bunsen burners used in experiments40 (For reference, the experimentally measured DNB decomposition temperature is...Klapötke, T. M.; Weigand, J. J. Combustion and Flame 2004, 139, 358. (2) Geith, J.; Klapöetke, T. M.; Weigand, J.; Holl, G. Propellants

  2. Effects of frame shadow on the PV character of a photovoltaic/thermal system

    International Nuclear Information System (INIS)

    Wang, Yunyun; Pei, Gang; Zhang, Longcan

    2014-01-01

    Highlights: • We proposed a method for predicting the performance of a partly shaded PV cell. • Even a small shadow can significantly affect the performance of a PV/T system. • A parallel circuit is better than a series circuit in addressing partial shadows. • The total output of a series circuit within a day/year is higher than that of a parallel circuit. - Abstract: Most photovoltaic/thermal (PV/T) systems have an air layer between the glass cover and the cells to minimize heat loss and to improve overall efficiency. This feature is not found in typical PV systems. The frame border that supports the glass cover casts a shadow over the cells near the frame when sunlight is slanted. This design is common in PV/T systems. The objective of this study is to determine the effects of a frame shadow on PV/T systems. A mathematical model of a PV module in a PV/T system is established. An experimental research on a partly shaded single cell is then conducted. Based on the module model and the results of the experiment, a single cell model that simulates the performance of partly shaded cells is developed and integrated into an existing system model. The new model can be applied to simulate frame shadow in a PV/T system. Results show that the performance of a partly shaded single cell can be calculated as the cell operates below the average irradiation intensity of the shaded and unshaded parts. In the worst-case scenario, the frame shadow can cause a 39.3% decrease in photoelectric efficiency. Although the parallel circuit performs better than the series circuit in minimizing loss caused by the frame shadow, the latter has a higher total output

  3. Mechanism of thermal decomposition of K{sub 2}FeO{sub 4} and BaFeO{sub 4}: A review

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Virender K., E-mail: vsharma@sph.tamhsc.edu [Texas A& M University, Department of Environmental and Occupational Health, School of Public Health (United States); Machala, Libor [Palacky University, Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science (Czech Republic)

    2016-12-15

    This paper presents thermal decomposition of potassium ferrate(VI) (K{sub 2}FeO{sub 4}) and barium ferrate(VI) (BaFeO{sub 4}) in air and nitrogen atmosphere. Mössbauer spectroscopy and nuclear forward scattering (NFS) synchrotron radiation approaches are reviewed to advance understanding of electron-transfer processes involved in reduction of ferrate(VI) to Fe(III) phases. Direct evidences of Fe {sup V} and Fe {sup IV} as intermediate iron species using the applied techniques are given. Thermal decomposition of K{sub 2}FeO{sub 4} involved Fe {sup V}, Fe {sup IV}, and K{sub 3}FeO{sub 3} as intermediate species while BaFeO{sub 3} (i.e. Fe {sup IV}) was the only intermediate species during the decomposition of BaFeO{sub 4}. Nature of ferrite species, formed as final Fe(III) species, of thermal decomposition of K{sub 2}FeO{sub 4} and BaFeO{sub 4} under different conditions are evaluated. Steps of the mechanisms of thermal decomposition of ferrate(VI), which reasonably explained experimental observations of applied approaches in conjunction with thermal and surface techniques, are summarized.

  4. Preparation and catalytic activities of LaFeO3 and Fe2O3 for HMX thermal decomposition.

    Science.gov (United States)

    Wei, Zhi-Xian; Xu, Yan-Qing; Liu, Hai-Yan; Hu, Chang-Wen

    2009-06-15

    Perovskite-type LaFeO(3) and alpha-Fe(2)O(3) with high specific surface areas were directly prepared with appropriate stearic acid-nitrates ratios by a novel stearic acid solution combustion method. The obtained powders were characterized by XRD, FT-IR and XPS techniques. The catalytic activities of perovskite-type LaFeO(3) and alpha-Fe(2)O(3) for the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were investigated by TG and TG-EGA techniques. The experimental results show that the catalytic activity of perovskite-type LaFeO(3) was much higher than that of alpha-Fe(2)O(3) because of higher concentration of surface-adsorbed oxygen (O(ad)) and hydroxyl of LaFeO(3). The study points out a potential way to develop new and more active perovskite-type catalysts for the HMX thermal decomposition.

  5. Performance and thermal decomposition analysis of foaming agent NPL-10 for use in heavy oil recovery by steam injection

    Directory of Open Access Journals (Sweden)

    Zhao Fa-Jun

    2018-02-01

    Full Text Available Foaming agents, despite holding potential in steam injection technology for heavy oil recovery, are still poorly investigated. In this work, we analyzed the performance of the foaming agent NPL-10 in terms of foam height and half-life under various conditions of temperature, pH, salinity, and oil content by orthogonal experiments. The best conditions of use for NPL-10 among those tested are T=220°C, pH 7, salinity 10000 mg·L–1 and oil content 10 g·L–1. Thermal decomposition of NPL-10 was also studied by thermogravimetric and differential thermal analyses. NPL-10 decomposes above 220°C, and decomposition is a two-step process. The kinetic triplet (activation energy, kinetic function and pre-exponential factor and the corresponding rate law were calculated for each step. Steps 1 and 2 follow kinetics of different order (n = 2 and ½, respectively. These findings provide some criteria for the selection of foaming agents for oil recovery by steam injection.

  6. Determination of Kinetic Parameters for Thermal Decomposition of Phenolic Ablative Materials by Multiple Heating Rate Method

    Science.gov (United States)

    1980-07-01

    the ratio method to analyze thermogravimetric data obtained for a urethane polymer. Baer, Hedges, Seader , Jayakar, and Wojcik6 heated samples of...reinforced polymers at heating rates up to 4200°C/min. The data were correlated by a numerical technique developed by Burningham and Seader .7 Friedman...Decomposition Through Thermogravimetric Analysis," Thermochimica Acta, No, 1, (1970), pp. 147-158. 6. A. D. Baer, J. H. Hedges, J. D. Seader , K. M. Jayakar

  7. Synthesis of transparent ZnO/PMMA nanocomposite films through free-radical copolymerization of asymmetric zinc methacrylate acetate and in-situ thermal decomposition

    International Nuclear Information System (INIS)

    Zhang Lin; Li Fan; Chen Yiwang; Wang Xiaofeng

    2011-01-01

    In this paper, a new and simple approach for in-situ preparation of transparent ZnO/poly(metyl methacrylate) (ZnO/PMMA) nanocomposite films was developed. Poly(methyl methacrylate)-co-poly(zinc methacrylate acetate) (PMMA-co-PZnMAAc) copolymer was synthesized via free-radical polymerization between methyl methacrylate (MMA) and zinc methacrylate acetate (ZnMAAc), where asymmetric ZnMAAc with only one terminal double bond (C=C) was applied to act as the precursor for ZnO nanocrystals and could avoid cross-link. Subsequently, transparent ZnO/PMMA nanocomposite films were obtained by in-situ thermal decomposition. Scanning electron microscope (SEM) image revealed that ZnO nanocrystals were homogeneously dispersed in PMMA matrix. With thermal decomposition time increasing, the absorption intensity in UV region and photoluminescence intensity of ZnO/PMMA nanocomposite films enhanced. However, the optical properties diminished when the thermal decomposition temperature increased. The TGA measurement displayed ZnO/PMMA nanocomposite films prepared by the in-situ synthesis method possessed better thermal stability compared with those prepared by the physical blending method and pristine PMMA films. - Highlights: → ZnO/PMMA hybrid films were prepared via free-radical polymerization and in-situ thermal decomposition. → ZnO NCs are homogeneously dispersed in the PMMA matrix and these films have good optical properties. → Thermal stability of these films is improved compared with those of physically blending ones.

  8. Synthesis of transparent ZnO/PMMA nanocomposite films through free-radical copolymerization of asymmetric zinc methacrylate acetate and in-situ thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lin [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Li Fan, E-mail: lfan@ncu.edu.cn [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Chen Yiwang, E-mail: ywchen@ncu.edu.cn [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang Xiaofeng [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China)

    2011-08-15

    In this paper, a new and simple approach for in-situ preparation of transparent ZnO/poly(metyl methacrylate) (ZnO/PMMA) nanocomposite films was developed. Poly(methyl methacrylate)-co-poly(zinc methacrylate acetate) (PMMA-co-PZnMAAc) copolymer was synthesized via free-radical polymerization between methyl methacrylate (MMA) and zinc methacrylate acetate (ZnMAAc), where asymmetric ZnMAAc with only one terminal double bond (C=C) was applied to act as the precursor for ZnO nanocrystals and could avoid cross-link. Subsequently, transparent ZnO/PMMA nanocomposite films were obtained by in-situ thermal decomposition. Scanning electron microscope (SEM) image revealed that ZnO nanocrystals were homogeneously dispersed in PMMA matrix. With thermal decomposition time increasing, the absorption intensity in UV region and photoluminescence intensity of ZnO/PMMA nanocomposite films enhanced. However, the optical properties diminished when the thermal decomposition temperature increased. The TGA measurement displayed ZnO/PMMA nanocomposite films prepared by the in-situ synthesis method possessed better thermal stability compared with those prepared by the physical blending method and pristine PMMA films. - Highlights: > ZnO/PMMA hybrid films were prepared via free-radical polymerization and in-situ thermal decomposition. > ZnO NCs are homogeneously dispersed in the PMMA matrix and these films have good optical properties. > Thermal stability of these films is improved compared with those of physically blending ones.

  9. Synthesis of MnFeO3 from the oxidate thermal decomposition of Mn(Fe(CN)5NO)*2H2O

    OpenAIRE

    Lick, Ileana Daniela; Soria, Delia Beatriz

    2017-01-01

    On the basis of previous studies about the pentacyanonitrosylmetallates whose thermal decomposition generates different type of oxides, the Mn[Fe(CN)5NO]·2H2O was used as raw material to give FeMnO3. The decomposition was studied by Thermogravimetric (TGA-DTG) and Differential Thermal Analysis (DTA) under air atmosphere, between room temperature and 1200°C. IR spectroscopy and XRPD, refined by Rietveld analysis, were used to follow the process. The XRPD of the sample heated at different tempe...

  10. Thermal decomposition study and biological characterization of zinc(II) 2-chlorobenzoate complexes with bioactive ligands

    Czech Academy of Sciences Publication Activity Database

    Findoráková, L.; Györyová, K.; Hudecová, D.; Mudroňová, D.; Kovářová, Jana; Homzová, K.; Nour El-Dien, F. A.

    2013-01-01

    Roč. 111, č. 3 (2013), s. 1771-1781 ISSN 1388-6150. [Central and Eastern European Conference on Thermal Analysis and Calorimetry /1./ - CEEC-TAC1. Craiova, 07.09.2011-10.09.2011] Institutional research plan: CEZ:AV0Z40500505 Keywords : zinc * 2-chlorobenzoate * thermal Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.206, year: 2013

  11. Thermal decomposition and antimicrobial activity of zinc(II) 2-bromobenzoates with organic ligands

    Czech Academy of Sciences Publication Activity Database

    Krajníková, A.; Györyová, K.; Hudecová, D.; Kovářová, Jana; Vargová, Z.

    2011-01-01

    Roč. 105, č. 2 (2011), s. 451-460 ISSN 1388-6150. [European Symposium on Thermal Analysis and Calorimetry /10./. Rotterdam, 22.08.2010-27.08.2010] Institutional research plan: CEZ:AV0Z40500505 Keywords : zinc 2-bromobenzoate * spectral properties * thermal behaviour Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.604, year: 2011

  12. Decomposition of thin titanium deuteride films: thermal desorption kinetics studies combined with microstructure analysis

    NARCIS (Netherlands)

    Lisowski, W.F.; Keim, Enrico G.; Kaszkur, Zbigniew; Smithers, M.A.; Smithers, Mark A.

    2008-01-01

    The thermal evolution of deuterium from thin titanium films, prepared under UHV conditions and deuterated in situ at room temperature, has been studied by means of thermal desorption mass spectrometry (TDMS) and a combination of scanning electron microscopy (SEM), transmission electron microscopy

  13. Assessment of a new method for the analysis of decomposition gases of polymers by a combining thermogravimetric solid-phase extraction and thermal desorption gas chromatography mass spectrometry.

    Science.gov (United States)

    Duemichen, E; Braun, U; Senz, R; Fabian, G; Sturm, H

    2014-08-08

    For analysis of the gaseous thermal decomposition products of polymers, the common techniques are thermogravimetry, combined with Fourier transformed infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS). These methods offer a simple approach to the decomposition mechanism, especially for small decomposition molecules. Complex spectra of gaseous mixtures are very often hard to identify because of overlapping signals. In this paper a new method is described to adsorb the decomposition products during controlled conditions in TGA on solid-phase extraction (SPE) material: twisters. Subsequently the twisters were analysed with thermal desorption gas chromatography mass spectrometry (TDS-GC-MS), which allows the decomposition products to be separated and identified using an MS library. The thermoplastics polyamide 66 (PA 66) and polybutylene terephthalate (PBT) were used as example polymers. The influence of the sample mass and of the purge gas flow during the decomposition process was investigated in TGA. The advantages and limitations of the method were presented in comparison to the common analysis techniques, TGA-FTIR and TGA-MS. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Predicting geometry of rectangular and hyperbolic fin profiles with temperature-dependent thermal properties using decomposition and evolutionary methods

    International Nuclear Information System (INIS)

    Bhowmik, Arka; Singla, Rohit K.; Roy, Pranab K.; Prasad, Dilip K.; Das, Ranjan; Repaka, Ramjee

    2013-01-01

    Highlights: • Dimensions of rectangular and hyperbolic fin are predicted for satisfying a given temperature. • Adomian Decomposition Method (ADM) is used to solve the forward problem. • DE in conjunction with ADM is used to solve the inverse problem. • Measurement error up to 5% is found to yield satisfactory reconstructions. - Abstract: This work proposes the application of the Adomian decomposition method (ADM) in conjunction with the differential evolution (DE) for simultaneously estimating the dimensions of a rectangular and hyperbolic profile annular fin in order to satisfy a prescribed temperature requirement. The thermal conductivity and the surface heat transfer are assumed to be temperature-dependent. The required temperature field has been obtained using ADM for cases, involving insulated and convective boundary conditions at the tip. Then, using an inverse scheme based on DE, required fins dimensions satisfying a prescribed temperature field are estimated. Owing to the correlated nature of the unknowns, many feasible solutions have been found to lie within a given range satisfying the given temperature field. This temperature field can offer the flexibility in selecting the designing parameters. The present study is expected to be useful for selecting the dimensions of a rectangular and hyperbolic profile annular fin which can satisfy the given temperature field

  15. In situ formation of a MoS2 -based inorganic-organic nanocomposite by directed thermal decomposition.

    Science.gov (United States)

    Djamil, John; Segler, Stefan A W; Bensch, Wolfgang; Schürmann, Ulrich; Deng, Mao; Kienle, Lorenz; Hansen, Sven; Beweries, Torsten; von Wüllen, Leo; Rosenfeldt, Sabine; Förster, Stephan; Reinsch, Helge

    2015-06-08

    Nanocomposites based on molybdenum disulfide (MoS2 ) and different carbon modifications are intensively investigated in several areas of applications due to their intriguing optical and electrical properties. Addition of a third element may enhance the functionality and application areas of such nanocomposites. Herein, we present a facile synthetic approach based on directed thermal decomposition of (Ph4 P)2 MoS4 generating MoS2 nanocomposites containing carbon and phosphorous. Decomposition at 250 °C yields a composite material with significantly enlarged MoS2 interlayer distances caused by in situ formation of Ph3 PS bonded to the MoS2 slabs through MoS bonds and (Ph4 P)2 S molecules in the van der Waals gap, as was evidenced by (31) P solid-state NMR spectroscopy. Visible-light-driven hydrogen generation demonstrates a high catalytic performance of the materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

  17. Thermal Stability and Decomposition Kinetics of AgO Submicron Particles Prepared by Potassium Persulfate Oxidation

    Directory of Open Access Journals (Sweden)

    Hui FENG

    2018-02-01

    Full Text Available In this study, AgO submicron particles for antimicrobial application were prepared by potassium persulfate oxidation. The characterization of AgO particles was performed by XRD, XPS, SEM, TEM and TGA analysis. Its decomposition kinetics was studied by Doyle mechanism equation, Coats-Redfern equation and Ozawa approximate integration. The results showed that the as-prepared powders were composed of monoclinic AgO and small amounts of carbonate. The average width of AgO particles was about 200 nm with a rod-like morphology. AgO submicron particles could be decomposed to be Ag2O at 123 °C. When the temperature was increased to 405 °C, Ag2O was further transformed to be Ag. The decomposition reaction of AgO was controlled by Avrami-Erofeev random nucleation and subsequently growth mechanism (A1 with the apparent activation energy of 88.34 kJ/mol and the reaction frequency factor of 4.88 × 109 s-1.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17052

  18. Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction

    Science.gov (United States)

    Brollo, Maria Eugênia F.; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J. A.; Pirota, Kleber R.; Knobel, Marcelo

    2014-10-01

    A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.

  19. Influence of experimental parameters on iron oxide nanoparticle properties synthesized by thermal decomposition: size and nuclear magnetic resonance studies

    Science.gov (United States)

    Belaïd, Sarah; Stanicki, Dimitri; Vander Elst, Luce; Muller, Robert N.; Laurent, Sophie

    2018-04-01

    A study of the experimental conditions to synthesize monodisperse iron oxide nanocrystals prepared from the thermal decomposition of iron(III) acetylacetonate was carried out in the presence of surfactants and a reducing agent. The influence of temperature, synthesis time and surfactant amounts on nanoparticle properties is reported. This investigation combines relaxometric characterization and size properties. The relaxometric behavior of the nanomaterials depends on the selected experimental parameters. The synthesis of iron oxide nanoparticles with a high relaxivity and a high saturation magnetization can be obtained with a short reaction time at high temperature. Moreover, the influence of surfactant concentrations determines the optimal value in order to produce iron oxide nanoparticles with a narrow size distribution. The optimized synthesis is rapid, robust and reproductive, and produces nearly monodisperse magnetic nanocrystals.

  20. 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.

  1. Deuterium isotope effects in the thermal decomposition of β-hydroxy ketones and β-hydroxy esters

    International Nuclear Information System (INIS)

    Quijano, J.; Rodrigues, M.M.; Yepes, M.S.; Gallego, L.H.

    1986-01-01

    In a previous publication it was proposed that β-hydroxy-ketones decompose thermally to mixtures of aldehydes and ketones in a reaction that is the reverse of the aldol condensation, and that β-hydroxy esters pyrolyze to form a mixture of the corresponding ester and aldehyde or ketone. This decomposition follows first-order kinetics and appears to be unimolecular. Based on these data it was proposed that the reaction involves a cyclic six-membered transition state. To further corroborate this mechanism, thermolysis was carried out with the hydrogen replaced by deuterium. The small primary isotope effect observed agrees with the proposed transition state geometry, and the low cumulative secondary deuterium effect is a good indication that no C-H bond is broken in the rate controlling step. (author)

  2. Thermal decomposition of barium ferrate(VI): Mechanism and formation of FeIV intermediate and nanocrystalline Fe2O3 and ferrite

    International Nuclear Information System (INIS)

    Machala, Libor; Sharma, Virender K.; Kuzmann, Ernö; Homonnay, Zoltán; Filip, Jan; Kralchevska, Radina P.

    2016-01-01

    Simple high-valent iron-oxo species, ferrate(VI) (Fe VI O 4 2− , Fe(VI)) has applications in energy storage, organic synthesis, and water purification. Of the various salts of Fe(VI), barium ferrate(VI) (BaFeO 4 ) has also a great potential as a battery material. This paper presents the thermal decomposition of BaFeO 4 in static air and nitrogen atmosphere, monitored by combination of thermal analysis, Mössbauer spectroscopy, X-ray powder diffraction, and electron-microscopic techniques. The formation of Fe IV species in the form of BaFeO 3 was found to be the primary decomposition product of BaFeO 4 at temperature around 190 °C under both studied atmospheres. BaFeO 3 was unstable in air reacting with CO 2 to form barium carbonate and speromagnetic amorphous iron(III) oxide nanoparticles (<5 nm). Above 600 °C, a solid state reaction between BaCO 3 and Fe 2 O 3 occurred, leading to the formation of barium ferrite nanoparticles, BaFe 2 O 4 (20–100 nm). - Highlights: • We explained the mechanism of thermal decomposition of barium ferrate(VI). • We confirmed the formation of Fe(IV) intermediate phase during the decomposition. • The mechanism of the decomposition is influenced by a presence of carbon dioxide.

  3. Surfactant controlled low-temperature thermal decomposition route to zinc oxide nanorods from zinc(II) acetylacetonate monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Purkayastha, Debraj Dhar; Sarma, Bedabrat; Bhattacharjee, Chira R., E-mail: crbhattacharjee@rediffmail.com

    2014-10-15

    Zinc oxide (ZnO) nanorods were synthesized via a low-temperature thermal decomposition of zinc(II) acetylacetonate monohydrate, [Zn(C{sub 5}H{sub 7}O{sub 2}){sub 2}].H{sub 2}O. A relatively inexpensive surfactant, octadecylamine (C{sub 18}H{sub 37}NH{sub 2}) served both as a reaction solvent and a capping agent during the synthesis of ZnO nanorods. The synthesized nanorods were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, UV–visible, and photoluminescence (PL) studies. The XRD spectrum furnished evidence for the hexagonal wurtzite structure of ZnO. TEM images revealed the material to be rod shaped having diameter 30 nm and length 200 nm. The HRTEM image showed that the lattice fringes between the two adjacent planes are 0.244 nm apart, which corresponds to the interplanar separation of the (1 0 1) plane of hexagonal ZnO. The electron diffraction (ED) pattern confirmed the single crystalline nature of the nanorods. The PL spectrum showed two UV emissions at 356 nm (∼3.48 eV) and 382 nm (∼3.25 eV). ZnO nanorods also showed very weak blue bands at 445, 453 and 470 nm. - Highlights: Low temperature thermal decomposition of zinc(II) acetylacetonate monohydrate gave zinc oxide nanorods. Powder XRD showed hexagonal wurtzite structure of ZnO having average diameter about 24 nm. TEM images revealed the material to be of rod shape having diameter 30 nm and length 200 nm. ZnO showed band gap luminescence at 356 nm, excitonic emission at 382 nm and defect related blue bands. The synthesis is simple and can act as a paradigm for obtaining various metal oxide nanomaterials.

  4. Synthesis, characterization and thermal decomposition kinetics of Sm(III)complex with 2,4-dichlorobenzoate and 2,2'-bipyridine

    International Nuclear Information System (INIS)

    Zhang Haiyan; Zhang Jianjun; Ren Ning; Xu, Su-Ling; Zhang Yonghua; Tian Liang; Song Huihua

    2008-01-01

    The complex of [Sm(2,4-DClBA) 3 (bipy)] 2 (2,4-DClBA, 2,4-dichlorobenzoate; bipy, 2,2'-bipyridine) was synthesized and characterized by elemental analysis, molar conductivity, IR and UV spectra. The thermal decomposition process of the complex was studied by means of TG-DTG and IR techniques. And its thermal decomposition kinetics was investigated via the analysis of the TG-DTG curves by jointly using double equal-double steps method and nonlinear integral isoconversional method. The activation energy E, the pre-exponential factor A and the most probable mechanism functions of the first decomposition stage were obtained. Meanwhile, the thermodynamic parameters (ΔH ≠ , ΔG ≠ and ΔS ≠ ) were also calculated. The lifetime equation at weight-loss of 10% was deduced as ln τ = -35.53 + 20200/T by isothermal thermogravimetric analysis

  5. Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

    International Nuclear Information System (INIS)

    Leduc, Jennifer; Mathur, Sanjay; Pacold, Joseph I.; Shuh, David K.; Dong, Chung-Li

    2018-01-01

    Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO 2 nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Leduc, Jennifer; Mathur, Sanjay [Institute of Inorganic Chemistry, University of Cologne (Germany); Pacold, Joseph I.; Shuh, David K. [Chemical Sciences Division, The Glenn T. Seaborg Center, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China)

    2018-01-17

    Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO{sub 2} nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. 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.

  8. preparation of La0.3Sr0.7CoO3-d perovskite by thermal decomposition of metal-EDTA complexes

    NARCIS (Netherlands)

    van Doorn, Rene H.E.; van Doorn, R.H.E.; Kruidhof, H.; Nijmeijer, Arian; Winnubst, Aloysius J.A.; Burggraaf, Anthonie; Burggraaf, Anthony J.

    1998-01-01

    Perovskite powders of La0.3Sr0.7CoO3–were prepared by the thermal decomposition of precursor complexes derived from nitrate solutions using ethylenediaminetetraacetic acid (EDTA) as a complexing agent. The calcination temperature is 920 °C. Powders thus obtained have a low carbon contamination.

  9. Effects of magnesium-based hydrogen storage materials on the thermal decomposition, burning rate, and explosive heat of ammonium perchlorate-based composite solid propellant.

    Science.gov (United States)

    Liu, Leili; Li, Jie; Zhang, Lingyao; Tian, Siyu

    2018-01-15

    MgH 2 , Mg 2 NiH 4 , and Mg 2 CuH 3 were prepared, and their structure and hydrogen storage properties were determined through X-ray photoelectron spectroscopy and thermal analyzer. The effects of MgH 2 , Mg 2 NiH 4 , and Mg 2 CuH 3 on the thermal decomposition, burning rate, and explosive heat of ammonium perchlorate-based composite solid propellant were subsequently studied. Results indicated that MgH 2 , Mg 2 NiH 4 , and Mg 2 CuH 3 can decrease the thermal decomposition peak temperature and increase the total released heat of decomposition. These compounds can improve the effect of thermal decomposition of the propellant. The burning rates of the propellant increased using Mg-based hydrogen storage materials as promoter. The burning rates of the propellant also increased using MgH 2 instead of Al in the propellant, but its explosive heat was not enlarged. Nonetheless, the combustion heat of MgH 2 was higher than that of Al. A possible mechanism was thus proposed. Copyright © 2017. Published by Elsevier B.V.

  10. 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.

  11. Thermal decomposition behavior of potassium and sodium jarosite synthesized in the presence of methylamine and alanine

    Energy Technology Data Exchange (ETDEWEB)

    J. Michelle Kotler; Nancy W. Hinman; C. Doc Richardson; Jill R. Scott

    2010-10-01

    Biomolecules, methylamine and alanine, found associated with natural jarosite samples peaked the interest of astrobiologists and planetary geologists. How the biomolecules are associated with jarosite remains unclear although the mechanism could be important for detecting biosignatures in the rock record on Earth and other planets. A series of thermal gravimetric experiments using synthetic K-jarosite and Na-jarosite were conducted to determine if thermal analysis could differentiate physical mixtures of alanine and methylamine with jarosite from samples where the methylamine or alanine was incorporated into the synthesis procedure. Physical mixtures and synthetic experiments with methylamine and alanine could be differentiated from one another and from the standards by thermal analysis for both the K-jarosite and Na-jarosite end-member suites. Changes included shifts in on-set temperatures, total temperature changes from on-set to final, and the presence of indicator peaks for methylamine and alanine in the physical mixture experiments.

  12. 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 χ...

  13. 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

    -base titration method as a function of temperature, time of exposure and the substrate material used. Findings: The study shows that there is a possibility of anhydride-like species formation during the thermal treatment of fluxes containing weak organic acids (WOAs) as activators (succinic and DL...

  14. Synthesis, structures and thermal decomposition of ammine MxB12H12complexes (M = Li, Na, Ca).

    Science.gov (United States)

    Hansen, Bjarne R S; Tumanov, Nikolay; Santoru, Antonio; Pistidda, Claudio; Bednarcik, Jozef; Klassen, Thomas; Dornheim, Martin; Filinchuk, Yaroslav; Jensen, Torben R

    2017-06-28

    A series of ammine metal-dodecahydro-closo-dodecaboranes, M x B 12 H 12 ·nNH 3 (M = Li, Na, Ca) were synthesized and their structural and thermal properties studied with in situ time-resolved synchrotron radiation powder X-ray diffraction, thermal analysis, Fourier transformed infrared spectroscopy, and temperature-programmed photographic analysis. The synthesized compounds, Li 2 B 12 H 12 ·7NH 3 , Na 2 B 12 H 12 ·4NH 3 and CaB 12 H 12 ·6NH 3 , contain high amounts of NH 3 , 43.3, 26.6 and 35.9 wt% NH 3 , respectively, which can be released and absorbed reversibly at moderate conditions without decomposition, thereby making the closo-boranes favorable 'host' materials for ammonia or indirect hydrogen storage in the solid state. In this work, fifteen new ammine metal dodecahydro-closo-dodecaborane compounds are observed by powder X-ray diffraction, of which six are structurally characterized, Li 2 B 12 H 12 ·4NH 3 , Li 2 B 12 H 12 ·2NH 3 , Na 2 B 12 H 12 ·4NH 3 , Na 2 B 12 H 12 ·2NH 3 , CaB 12 H 12 ·4NH 3 and CaB 12 H 12 ·3NH 3 . Li 2 B 12 H 12 ·4NH 3 and Na 2 B 12 H 12 ·4NH 3 are isostructural and monoclinic (P2 1 /n) whereas Na 2 B 12 H 12 ·2NH 3 and CaB 12 H 12 ·3NH 3 are both trigonal with space groups P3[combining macron]m1 and R3[combining macron]c, respectively. Generally, coordination between the metal and the icosahedral closo-borane anion is diverse and includes point sharing, edge sharing, or face sharing, while coordination of ammonia always occurs via the lone pair on nitrogen to the metal. Furthermore, a liquid intermediate is observed during heating of Li 2 B 12 H 12 ·7NH 3 . This work provides deeper insight into the structural, physical, and chemical properties related to thermal decomposition and possible ammonia and hydrogen storage.

  15. Moessbauer spectroscopic studies of thermal decomposition products in substituted pentacyanoferrate(II) and bridged binuclear complexes

    International Nuclear Information System (INIS)

    Lanjewar, R.B.; Garg, A.N.

    1995-01-01

    Moessbauer spectra of substituted pentacyanoferrates(II) of the type Na 3 [Fe(CN) 5 L].xH 2 O where L = pyrrolidine, piperidine, 3-cyanopyridine, nicotinic acid and nicotinamide and binuclear complexes of the formulae Na 6 [Fe(CN) 5 L(CN) 5 Fe].xH 2 O where L = 4-cyanopyridine and pyrazine exhibit well resolved quadrupole doublet, ΔE Q = 0.73-0.99 mms -1 at room temperature. The isomer shift values, δ = 0.23-0.30 mms -1 suggest iron atoms in +2 low spin state. The complexes start decomposing at 50 degC yielding residual weight(49.1-55.2%) in the temperature range 700-800 degC. The Moessbauer spectra recorded after heating at 200 degC exhibit an asymmetric doublet suggesting partial decomposition. At 500 degC, a six line pattern starts appearing which on further heating at > 700 degC turns into eight or ten lines suggesting the formation of α-Fe 2 O 3 of different particle sizes and iron carbide along with metal phase. (author). 2 figs., 1 tab

  16. Properties and thermal decomposition of polypyrrole prepared in the presence of sodium bis(2-ethylhexyl) sulfosuccinate

    Czech Academy of Sciences Publication Activity Database

    Omastová, M.; Rychlý, J.; Trchová, Miroslava; Kovářová, Jana

    2004-01-01

    Roč. 7, č. 6 (2004), s. 633-646 ISSN 1385-772X R&D Projects: GA ČR GA202/02/0698 Grant - others:GA MŠ SR(SK) GAV2/4024/04 Institutional research plan: CEZ:AV0Z4050913 Keywords : polypyrrole * thermal ageing * chemical polymerization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.661, year: 2004

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

    OpenAIRE

    Eugenio Aulisa; Sandro Manservisi; Padmanabhan Seshaiyer

    2009-01-01

    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 ap...

  18. Investigation of the thermal decomposition of a new titanium dioxide material

    Czech Academy of Sciences Publication Activity Database

    Palkovská, Monika; Slovák, V.; Šubrt, Jan; Boháček, Jaroslav; Barbieriková, Z.; Brezová, V.; Fajgar, Radek

    2016-01-01

    Roč. 125, č. 3 (2016), s. 1071-1078 ISSN 1388-6150 R&D Projects: GA ČR(CZ) GA14-20744S; GA MŠk(CZ) 7AMB14SK178 Institutional support: RVO:61388980 ; RVO:67985858 Keywords : Titanium dioxide * Rod-shaped structure * Thermal analysis * Evolved gas analysis * EPR spectroscopy Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UCHP-M) Impact factor: 1.953, year: 2016

  19. Equivalence of the EMD- and NEMD-based decomposition of thermal conductivity into microscopic building blocks.

    Science.gov (United States)

    Matsubara, Hiroki; Kikugawa, Gota; Ishikiriyama, Mamoru; Yamashita, Seiji; Ohara, Taku

    2017-09-21

    Thermal conductivity of a material can be comprehended as being composed of microscopic building blocks relevant to the energy transfer due to a specific microscopic process or structure. The building block is called the partial thermal conductivity (PTC). The concept of PTC is essential to evaluate the contributions of various molecular mechanisms to heat conduction and has been providing detailed knowledge of the contribution. The PTC can be evaluated by equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) in different manners: the EMD evaluation utilizes the autocorrelation of spontaneous heat fluxes in an equilibrium state whereas the NEMD one is based on stationary heat fluxes in a non-equilibrium state. However, it has not been fully discussed whether the two methods give the same PTC or not. In the present study, we formulate a Green-Kubo relation, which is necessary for EMD to calculate the PTCs equivalent to those by NEMD. Unlike the existing theories, our formulation is based on the local equilibrium hypothesis to describe a clear connection between EMD and NEMD simulations. The equivalence of the two derivations of PTCs is confirmed by the numerical results for liquid methane and butane. The present establishment of the EMD-NEMD correspondence makes the MD analysis of PTCs a robust way to clarify the microscopic origins of thermal conductivity.

  20. Equivalence of the EMD- and NEMD-based decomposition of thermal conductivity into microscopic building blocks

    Science.gov (United States)

    Matsubara, Hiroki; Kikugawa, Gota; Ishikiriyama, Mamoru; Yamashita, Seiji; Ohara, Taku

    2017-09-01

    Thermal conductivity of a material can be comprehended as being composed of microscopic building blocks relevant to the energy transfer due to a specific microscopic process or structure. The building block is called the partial thermal conductivity (PTC). The concept of PTC is essential to evaluate the contributions of various molecular mechanisms to heat conduction and has been providing detailed knowledge of the contribution. The PTC can be evaluated by equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) in different manners: the EMD evaluation utilizes the autocorrelation of spontaneous heat fluxes in an equilibrium state whereas the NEMD one is based on stationary heat fluxes in a non-equilibrium state. However, it has not been fully discussed whether the two methods give the same PTC or not. In the present study, we formulate a Green-Kubo relation, which is necessary for EMD to calculate the PTCs equivalent to those by NEMD. Unlike the existing theories, our formulation is based on the local equilibrium hypothesis to describe a clear connection between EMD and NEMD simulations. The equivalence of the two derivations of PTCs is confirmed by the numerical results for liquid methane and butane. The present establishment of the EMD-NEMD correspondence makes the MD analysis of PTCs a robust way to clarify the microscopic origins of thermal conductivity.

  1. Quantum chemical study of the thermal decomposition of o-quinone methide (6-methylene-2,4-cyclohexadien-1-one).

    Science.gov (United States)

    Silva, Gabriel da; Bozzelli, Joseph W

    2007-08-16

    o-Quinone methide (o-QM), or 6-methylene-2,4-cyclohexadiene-1-one, has been identified as an important intermediate in lignin and alkyl benzene combustion, and the thermal decomposition of o-QM is therefore relevant to the combustion of transportation fuels (which contain toluene) and of biomass and low-rank coals (which contain lignin). We present a comprehensive reaction mechanism for the unimolecular conversion of o-QM to the reaction intermediates tropone and fulvene, calculated using theoretical quantum chemical techniques. Enthalpies of formation for all reactants, products, and intermediates are calculated using the CBS-QB3 theoretical method. Transition states are determined with the CBS-QB3 method, which we use to obtain rate constants as a function of temperature from transition-state theory, with Wigner tunneling corrections applied to hydrogen-shift reactions. Barrier heights are also calculated with the BB1K density functional theory (DFT) method for thermochemical kinetics. Reaction pathways are identified leading to tropone (which rapidly decomposes to benzene + CO) and to fulvene + CO, via initial hydrogen transfer to 2-hydroxyphenylcarbene and via ring opening to 1,3,5,6-heptatetraen-1-one, respectively. Quantum Rice-Ramsperger-Kassel (QRRK) theory analysis of the reaction kinetics indicates that the dominant reaction pathway is formation of tropone via 2-hydroxyphenylcarbene; the formation of fulvene + CO via initial ring opening constitutes a secondary pathway, which becomes more important with increasing temperature. Our calculations, using BB1K barrier heights, yield the rate equation k(T) [s(-1)] = 2.64 x 10(14) exp(-35.9/T [K]) for o-QM decomposition, which is in relatively good agreement with the experimental rate equation. Calculations provide an apparent activation energy of 71.3 kcal mol(-1), versus 67.2 kcal mol(-1) from experiment.

  2. 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.

  3. 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.

  4. Studies on thermal decomposition of uranium(VI) and thorium(IV) complexes of o-carboxy N,N'-dimethylbenzylamine by thermoanalytical techniques in static air atmosphere

    International Nuclear Information System (INIS)

    Khan, S.; Anwar, C.J.

    2006-01-01

    The o-carboxy N-N'-dimethylbenzylamine uranium(VI) and thorium(IV) complexes, o-C 6 H 4 COOHCH 2 N-(CH 3 ) 2 UO 2 SO 4 (I), o-C 6 H 4 COOHCH 2 N(CH 3 ) 2 UO 2 (NO 3 ) 2 (II), o-C 6 H 4 COOHCH 2 N(CH 3 ) 2 UO 2 Cl 2 (III), and o-C 6 H 4 CO-OHCH 2 N(CH 3 ) 2 Th(NO 3 ) 4 (IV) were prepared and studied by means of thermoanalytical techniques in static air atmosphere to understand their mode of decomposition and thermal stability. Their compositions were investigated by elemental analysis in order to ensure their purity, and structure elucidations were based on proton NMR and IR spectra. Study of their thermal decomposition showed that they pyrolyzed in stages: the degradation of square bipyramidal complexes (I and III) occurred in four stages; hexagonal bipyramidal complex (II) also followed the same pattern. The decomposition of bicapped square antiprism complex (IV) proceeded in three steps. The thermal decomposition of these complexes occurred with the loss of inorganic and organic fragments and exhibited almost the same mode of decomposition. The composition of the intermediate formed during degradation was confirmed by microanalysis and IR spectroscopy. The residue after heating above 480 C corresponded to metal oxide. It follows from the results that the thermal stability of the complexes increases in the following sequence: Complex II, Complex IV < Complex III < Complex I. (orig.)

  5. Chemical evolution studies: the radiolysis and thermal decomposition of malonic acid

    International Nuclear Information System (INIS)

    Cruz-Castaneda, J.; Negron-Mendoza, A.; Heredia, A.; Ramos-Bernal, S.; Villafane-Barajas, S.; Frias, D.; Colin-Garcia, M.

    2015-01-01

    In the context of chemical evolution a simulation of a hydrothermal vent was performed. The thermolysis and radiolysis of malonic acid in aqueous solution were studied. The thermolysis was done by heating the samples (95 deg C) and radiolysis using gamma radiation. Products were identified by gas chromatography and gas chromatography-mass spectrometry. The thermal treatment produced acetic acid and CO 2 . The radiolysis experiments yield carbon dioxide, acetic acid, and di- and tricarboxylic acids. A theoretical model of the chemical process occurring under irradiation was developed; this was able to reproduce formation of products and the consumption of malonic acid. (author)

  6. Study of thermal treatment combined with radiation on the decomposition of polysaccharides in sugarcane bagasse

    Science.gov (United States)

    Duarte, C. L.; Ribeiro, M. A.; Oikawa, H.; Mori, M. N.

    2013-03-01

    Sugarcane bagasse pretreatment is a physical and chemical process that reduces the crystalline structure and disrupts the hydrogen bonding of cellulose to improve the accessibility to hydrolytic depolymerization reactions. The combination of pretreatment technologies intends to decrease the severity of the processes and to avoid excessive sugar degradation and formation of toxic by-products. An effective pretreatment preserves the pentose fractions and limits the formation of degradation products that inhibits the growth of fermentative microorganisms. This study presents the evaluation of the cleavage of polysaccharides from sugarcane bagasse using ionizing radiation combined with thermal and diluted acid treatment to further enzymatic or chemical hydrolysis of cellulose. Samples of sugarcane bagasse were irradiated using a Radiation Dynamics electron beam accelerator with 1.5 MeV and 37 kW, with different absorbed doses, and then were submitted to thermal and acid (0.1% sulfuric acid, m/m) hydrolysis for 10, 20 and 40 min at 180 °C. Taking into account the sugars and by-products liberated in these treatments the conversion rates of cellulose and hemicelluloses were calculated.

  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. Pyrolysis and combustion kinetics of sludge–camphor pellet thermal decomposition using thermogravimetric analysis

    International Nuclear Information System (INIS)

    Jiang, Longbo; Yuan, Xingzhong; Li, Hui; Xiao, Zhihua; Liang, Jie; Wang, Hou; Wu, Zhibin; Chen, Xiaohong; Zeng, Guangming

    2015-01-01

    Highlights: • First attempt on pyrolysis/combustion kinetics of densified sludge–camphor pellet. • E a value for the sludge–camphor pellet was lower than the single pellet (SP, CP). • Enhanced thermal degradation takes place in air as oxygen acceleration effect. • E a is highly depended on conversion indicating a complex multi-step mechanism. • Some synergistic effects happen between sludge and camphor during pyrolysis. - Abstract: The pyrolysis and combustion characteristics of sludge pellet (SP), camphor pellet (CP) and sludge–camphor pellet (SCP, 50% sludge ratio) were studied via thermogravimetric analysis. The samples were heated from ambient temperature to 1073 K at various heating rate (5, 10, 20, 40 K/min) in nitrogen and air atmosphere. Heating rate had a substantial effect on mass loss and mass loss rate in both pyrolyzing and oxidizing conditions. The thermal behavior of SCP was the integration of SP and CP. Onset and offset temperatures of SCP lay between that of CP and SP in various heating rate. The kinetic parameters of the process were evaluated using two iso-conversional models (Flynn–Wall–Ozawa and Starink). Kinetic analysis results showed that activation energy was highly depended on conversion which indicated the existence of a complex multi-step mechanism. E α value for the sludge–camphor pellet (SCP) was lower than the single pellet (SP and CP). Some synergistic effects happened between sludge and camphor during pyrolysis.

  10. Thermal decomposition of electronic wastes: Mobile phone case and other parts

    International Nuclear Information System (INIS)

    Molto, Julia; Egea, Silvia; Conesa, Juan Antonio; Font, Rafael

    2011-01-01

    Highlights: → Pyrolysis and combustion of different parts of mobile phones produce important quantities of CO and CO 2 . → Naphthalene is the most abundant PAH obtained in the thermal treatment of mobile phones. → Higher combustion temperature increases the chlorinated species evolved. - Abstract: Pyrolysis and combustion runs at 850 o C in a horizontal laboratory furnace were carried out on different parts of a mobile phone (printed circuit board, mobile case and a mixture of both materials). The analyses of the carbon oxides, light hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorodibenzo-p-dioxin, polychlorodibenzofurans (PCDD/Fs), and dioxin-like PCBs are shown. Regarding semivolatile compounds, phenol, styrene, and its derivatives had the highest yields. In nearly all the runs the same PAHs were identified, naphthalene being the most common component obtained. Combustion of the printed circuit board produced the highest emission factor of PCDD/Fs, possibly due to the high copper content.

  11. 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

  12. 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

  13. Desorption of C60 upon thermal decomposition of cesium C58 fullerides.

    Science.gov (United States)

    Ulas, Seyithan; Löffler, Daniel; Weis, Patrick; Böttcher, Artur; Kappes, Manfred M

    2012-03-21

    A monodispersed fullerene material comprising exclusively C(58) cages was doped with Cs to generate Cs(x)C(58) films of various compositions. The resulting modified properties have been studied using a variety of surface analysis methods with emphasis on thermal desorption and ultraviolet photoelectron spectroscopies. Cs doping raises the thermal stability of C(58) films which are characterized by quasi-covalent cage-cage bonds between annelated pentagon sites. Desorption mass spectra show emission of significant amounts of C(60) at elevated temperatures implying that Cs doping can activate C(58)→C(60) conversion in the condensed phase. In the case of saturated Cs(x)C(58) films, up to 4.5% of the initially deposited C(58) can be desorbed as C(60). From the spectroscopic data, we infer that Cs insertion and transport into the interstitial sites of the C(58) solid is accompanied by spontaneous electron transfer to the electronegative fullerene framework-leading to a weakening of intercage carbon-carbon bonds. At the same time, the overall cohesion of the solid film is enhanced by the formation of multiple ionic Cs(+) (β)C(58) (-) (δ) interactions. Near 800 K, Cs(+) activates∕catalyzes concerted disproportionation reactions resulting in the transfer of C(2) from C(58) (-) (δ) to neighbouring cages to yield C(60) (and C(56)). Heating Cs(x)C(58) films to beyond this temperature range yields a (high temperature) stable reaction product with a significantly modified UP spectrum and a finite density of states at the Fermi level. © 2012 American Institute of Physics

  14. Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Mihály T.; Bertóti, Imre, E-mail: bertoti.imre@ttk.mta.hu; Mohai, Miklós; Németh, Péter; Jakab, Emma; Szabó, László; Szépvölgyi, János

    2017-02-15

    In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN){sub 2}. XPS and TEM show that in heat treatment at 450 °C for 1 h in Ar, loss of nitrogen and carbon occurs and small, 5–30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60–200 nm size and well faceted Au particles develop together with a fibrous (CN){sub n} polymer phase, and the Au crystallites are covered by a 3–5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4–20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar{sup +} ion bombardment with 2500 eV energy, 5–30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications. - Graphical abstract: Proposed scheme of the decomposition mechanism of AuCN samples: heat treatment in Ar flow (a) and in sealed ampoule (b); Ar{sup +} ion treatment at 300 eV (c) and at 2500 eV (d). Cross section sketches

  15. Combined TGA-MS kinetic analysis of multistep processes. Thermal decomposition and ceramification of polysilazane and polysiloxane preceramic polymers.

    Science.gov (United States)

    García-Garrido, C; Sánchez-Jiménez, P E; Pérez-Maqueda, L A; Perejón, A; Criado, José M

    2016-10-26

    The polymer-to-ceramic transformation kinetics of two widely employed ceramic precursors, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (TTCS) and polyureamethylvinylsilazane (CERASET), have been investigated using coupled thermogravimetry and mass spectrometry (TG-MS), Raman, XRD and FTIR. The thermally induced decomposition of the pre-ceramic polymer is the critical step in the synthesis of polymer derived ceramics (PDCs) and accurate kinetic modeling is key to attaining a complete understanding of the underlying process and to attempt any behavior predictions. However, obtaining a precise kinetic description of processes of such complexity, consisting of several largely overlapping physico-chemical processes comprising the cleavage of the starting polymeric network and the release of organic moieties, is extremely difficult. Here, by using the evolved gases detected by MS as a guide it has been possible to determine the number of steps that compose the overall process, which was subsequently resolved using a semiempirical deconvolution method based on the Frasier-Suzuki function. Such a function is more appropriate that the more usual Gaussian or Lorentzian functions since it takes into account the intrinsic asymmetry of kinetic curves. Then, the kinetic parameters of each constituent step were independently determined using both model-free and model-fitting procedures, and it was found that the processes obey mostly diffusion models which can be attributed to the diffusion of the released gases through the solid matrix. The validity of the obtained kinetic parameters was tested not only by the successful reconstruction of the original experimental curves, but also by predicting the kinetic curves of the overall processes yielded by different thermal schedules and by a mixed TTCS-CERASET precursor.

  16. 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.

  17. 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.

  18. 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.

  19. Hexagonal ZnO porous plates prepared from microwave synthesized layered zinc hydroxide sulphate via thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Machovsky, Michal, E-mail: machovsky@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Kuritka, Ivo, E-mail: ivo@kuritka.net [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Sedlak, Jakub, E-mail: j1sedlak@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Pastorek, Miroslav, E-mail: pastorek@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic)

    2013-10-15

    Graphical abstract: - Highlights: • Zinc hydroxy sulphate was synthesized in 3 min via microwave hydrothermal route. • Zinc hydroxy sulphate was converted into mesh like porous ZnO by calcining at 900°. • The process of transformation is topotactic. - Abstract: Layered zinc hydroxide sulphate (ZHS) was prepared by microwave-assisted hydrothermal precipitation of zinc sulphate monohydrate with hexamethylenetetramine. Under ambient conditions, the structure of ZHS determined by X-ray diffraction (XRD) was found to be a mixture of zinc hydroxide sulphate pentahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·5H{sub 2}O and tetrahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·4H{sub 2}O. Fourier transform infrared (FTIR) spectroscopy was used for characterization of the prepared materials. Based on the interpretation of ZHS's thermal decomposition profile obtained by thermogravimetric analysis, ZnO of high purity was prepared by calcination at 900 °C for 2 h. The structure of the resulting ZnO was confirmed by the XRD. The morphology examination by scanning electron microscopy revealed a porous mesh-like ZnO structure developed from the ZHS precursor at the expense of mass removal due to the release of water and sulphate during the calcination.

  20. 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 N 2 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.

  1. Magnetic and power absorption measurements on iron oxide nanoparticles synthesized by thermal decomposition of Fe(acac)3

    Science.gov (United States)

    Jović Orsini, N.; Babić-Stojić, B.; Spasojević, V.; Calatayud, M. P.; Cvjetićanin, N.; Goya, G. F.

    2018-03-01

    Iron oxide magnetic nanoparticles with diameters d, 7 nm ≤ d ≤ 12 nm, were synthesized by thermal decomposition of Fe(acac)3. Different experimental conditions, keeping constant concetration of Fe ions in solvent, showed that the heating rates is the most important parameter determining the final particle size. Use of two different solvents, 1-eicosene and 1-octadecene, yielded similar nanoparticle sizes (7.1 nm ≤ d ≤ 7.5 nm), but different magnetic anisotropies. All samples were superparamagnetic at room temperature. Spin disordering was inferred in samples coated with trioctylphosphine oxide (TOPO) co-ligand in addition to oleic acid and oleyamine. The heating ability of ∼12 nm-sized nanoparticles dispersed in hexane under alternating magnetic fields (3.98 kA/m ≤ H0 ≤ 23.87 kA/m; 229.3 kHz ≤ f ≤ 828 kHz) has been studied, finding a nearly quadratic dependence upon H0, as expected from the linear response theory.

  2. 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.

  3. 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.

  4. 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.

  5. Estudo da decomposição térmica de propelente sólido compósito de baixa emissão de fumaça Study of thermal decomposition of a smokelles propellant

    Directory of Open Access Journals (Sweden)

    Jony Andrade

    2008-01-01

    Full Text Available The thermal decomposition of hydroxyl-terminated polybutadiene (HTPB/ammonium nitrate (AN based propellants, so called smokeless formulations, and raw materials were investigated by differential scanning calorimetry (DSC and thermogravimetry (TG. The thermoanalytical profile of different components and of propellant were evaluated and the Arrhenius parameters for the thermal decomposition of the propellant sample were determined by the Ozawa method. The kinetic parameters of the thermal decomposition of propellant samples were determined by DSC measurements. The values obtained for activation energy (Ea and pre-exponential factor were 163 kJ mol-1 and 1.94x10(6 min-1.

  6. Formation of TiO/Al2O3/C Composite in Thermal Co-decomposition of Aluminium(III) Acetylacetonate and Titanium(IV) Oxyacetylacetonate.

    Czech Academy of Sciences Publication Activity Database

    Kovářík, T.; Pokorná, Dana; Urbanová, Markéta; Bezdička, Petr; Bastl, Zdeněk; Kupčík, Jaroslav; Křenek, T.; Pola, M.; Kullová, L.; Pola, Josef

    2016-01-01

    Roč. 117, JAN 2016 (2016), s. 182-190 ISSN 0165-2370 R&D Projects: GA TA ČR TA04020860 Institutional support: RVO:67985858 ; RVO:61388980 ; RVO:61388955 Keywords : thermal co-decomposition * aluminium(III) acetylacetonate * titanium(IV) oxyacetylacetonate * titanium monoxide * alumina * Carbona Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.471, year: 2016

  7. 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

  8. 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.

  9. Fabrication of porous MgCo2O4 with rod-like morphology and its superb catalytic activity towards ammonium perchlorate thermal decomposition

    Science.gov (United States)

    Li, Gang; Liu, Xiaoli; Bai, Weiyang

    2018-03-01

    In this paper, porous MgCo2O4 with rod-like morphology was successfully synthesized through the thermal treatment of metal oxalates precursor originated by the reaction of metal sulfates and oxalic acid, without the addition of other additives. The porous rod-like MgCo2O4, with a diameter of several hundred nanometers and a length of several micrometers, was formed through the agglomeration of numerous crystalline grains sized in 10–25 nm. Its catalytic effect on ammonium perchlorate (AP) thermal decomposition was evaluated using differential scanning calorimetry (DSC) techniques. It was found that the pyrolysis temperature of AP reduced by 129 °C and the heat release increased more than 3.19-fold with a 2 wt% addition of MgCo2O4. Meanwhile, the addition of MgCo2O4 resulted in an AP decomposition activation energy reduction from 216 kJ mol‑1 to 155 kJ mol‑1, calculated using the Kissinger correlation. This study provides new insights into the design and development of high performance catalysts for AP thermal decomposition.

  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. Shared Reed-Muller Decision Diagram Based Thermal-Aware AND-XOR Decomposition of Logic Circuits

    Directory of Open Access Journals (Sweden)

    Apangshu Das

    2016-01-01

    Full Text Available The increased number of complex functional units exerts high power-density within a very-large-scale integration (VLSI chip which results in overheating. Power-densities directly converge into temperature which reduces the yield of the circuit. An adverse effect of power-density reduction is the increase in area. So, there is a trade-off between area and power-density. In this paper, we introduce a Shared Reed-Muller Decision Diagram (SRMDD based on fixed polarity AND-XOR decomposition to represent multioutput Boolean functions. By recursively applying transformations and reductions, we obtained a compact SRMDD. A heuristic based on Genetic Algorithm (GA increases the sharing of product terms by judicious choice of polarity of input variables in SRMDD expansion and a suitable area and power-density trade-off has been enumerated. This is the first effort ever to incorporate the power-density as a measure of temperature estimation in AND-XOR expansion process. The results of logic synthesis are incorporated with physical design in CADENCE digital synthesis tool to obtain the floor-plan silicon area and power profile. The proposed thermal-aware synthesis has been validated by obtaining absolute temperature of the synthesized circuits using HotSpot tool. We have experimented with 29 benchmark circuits. The minimized AND-XOR circuit realization shows average savings up to 15.23% improvement in silicon area and up to 17.02% improvement in temperature over the sum-of-product (SOP based logic minimization.

  12. 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.

  13. Demonstration test results of organic materials' volumetric reduction using bio-ethanol, thermal decomposition and burning

    International Nuclear Information System (INIS)

    Tagawa, Akihiro; Watanabe, Masahisa

    2013-01-01

    To discover technologies that can be utilized for decontamination work and verify their effects, economic feasibility, safety, and other factors, the Ministry of the Environment launched the 'FY2011 Decontamination Technology Demonstrations Project' to publicly solicit decontamination technologies that would be verified in demonstration tests and adopted 22 candidates. JAEA was commissioned by the Ministry of the Environment to provide technical assistance related to these demonstrations. This paper describes the volume reduction due to bio-ethanol, thermal decomposition and burning of organic materials in this report. The purpose of this study is that to evaluate a technique that can be used as biomass energy source, while performing volume reduction of contamination organic matter generated by decontamination. An important point of volume reduction technology of contaminated organic matter, is to evaluate the mass balance in the system. Then, confirming the mass balance of radioactive material and where to stay is important. The things that are common to all technologies, are ensuring that the radioactive cesium is not released as exhaust gas, etc.. In addition, it evaluates the cost balance and energy balance in order to understand the applicability to the decontamination of volume reduction technology. The radioactive cesium remains in the carbides when organic materials are carbonized, and radioactive cesium does not transfer to bio-ethanol when organic materials are processed for bio-ethanol production. While plant operating costs are greater if radioactive materials need to be treated, if income is expected by business such as power generation, depreciation may be calculated over approximately 15 years. (authors)

  14. Moessbauer and EXAFS studies of amorphous iron produced by thermal decomposition of carbonyl iron in liquid phase

    International Nuclear Information System (INIS)

    Nomura, Kiyoshi; Tanaka, Junichi; Ujihira, Yusuke; Takahashi, Tamotu; Uchida, Yasuzo

    1990-01-01

    Decomposition of iron carbonyl Fe(CO) 5 and Fe 2 (CO) 9 in liquid phase gave amorphous and crystalline iron powders in the absence and presence of catalyst, respectively. The hyperfine fields were large in amorphous phases prepared from Fe(CO) 5 than from Fe 2 (CO) 9 . Crystalline iron, iron carbide and a trace amount of Fe 3 O 4 were detected in the decomposition products of the amorphous phase prepared from Fe(CO) 5 , and iron carbide was mainly included in the decomposition products of the amorphous phase prepared from Fe 2 (CO) 9 . (orig.)

  15. 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 decompos......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...

  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 foundry resins: A determination of organic products by thermogravimetry–gas chromatography–mass spectrometry (TG–GC–MS

    Directory of Open Access Journals (Sweden)

    A. Kmita

    2018-03-01

    Full Text Available The article presents the results of research on thermal decomposition of Ester-Cured Alkaline Phenolic No-Bake (ALPHASET binders used in molding technology. In the ALPHASET system phenol-formaldehyde resin of resole type is cured with a liquid mixture of esters. Under the influence of the molten metal the thermal decomposition of the binder follows, resulting in the evolution of gases, often harmful, e.g. from benzene, toluene, ethylbenzene and xylenes (BTEX or Polycyclic Aromatic Hydrocarbon (PAH groups. The identification of gases evolved during the pyrolysis of the binders was carried out and their decomposition temperatures were determined using the Thermogravimetry–Gas Chromatography–Mass Spectrometry (TG–GC–MS technique. The tests were subjected to two types of binders from different manufacturers. Among the products of pyrolysis there have been identified mainly benzene and its derivatives, and phenol and its derivatives. Compounds identified in pyrolytic gas are largely considered to be harmful to humans and the environment (some of the compounds are carcinogenic and mutagenic. The presented results of the TG–GC–MS measurements show that the applied analytic methods are feasible to perform a qualitative and also quantitative characterization of the binder samples.

  18. Solvent effects and secondary isotope effects for probing diradical character in the thermal decarboxylation of β-peroxylactones

    International Nuclear Information System (INIS)

    Adam, W.; Cueto, O.; Guedes, L.N.; Rodriguez, L.O.

    1978-01-01

    The lack of solvent effects in the activation parameters and product distribution and the lack of secondary deuterium isotope effects at the α-carbon and β-alkyl migrant substantiates that the thermal decarboxylation of β-peroxy lactones proceeds via a 1,5-diradical

  19. 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

  20. Thermal decomposition behavior of the rare-earth ammonium sulfate R2(SO4)3.(NH4)2SO4

    International Nuclear Information System (INIS)

    Nagai, Tsukasa; Tamura, Shinji; Imanaka, Nobuhito

    2010-01-01

    Rare-earth ammonium sulfate octahydrates of R 2 (SO 4 ) 3 .(NH 4 ) 2 SO 4 .8H 2 O (R=Pr, Nd, Sm, and Eu) were synthesized by a wet process, and the stable temperature region for the anhydrous R 2 (SO 4 ) 3 .(NH 4 ) 2 SO 4 form was clarified by thermogravimetry/differential thermal analysis, infrared, Raman, and electrical conductivity measurements. Detailed characterization of these double salts demonstrated that the thermal stability of anhydrous R 2 (SO 4 ) 3 .(NH 4 ) 2 SO 4 is different between the Pr, Nd salts and the Sm, Eu salts, and the thermal decomposition behavior of these salts was quite different from the previous reports. - Graphical abstract: Stable temperature range of anhydrous rare-earth ammonium sulfate R 2 (SO 4 ) 3 .(NH 4 ) 2 SO 4 was clarified by thermogravimetry/differential thermal analysis, infrared, Raman, and electrical conductivity measurements. Since the previous reports were based only on thermal analysis, the present work has more accurately determined the exact thermal stability of rare-earth ammonium sulfate solids.

  1. A two-dimensional bismuth coordination polymer with tartaric acid: synthesis, characterization and thermal decomposition to Bi.sub.2./sub.O.sub.3./sub. nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Ahadiat, G.; Tabatabaee, M.; Gholivand, K.; Zare, K.; Dušek, Michal; Kučeráková, Monika

    2017-01-01

    Roč. 16, č. 1 (2017), s. 7-16 ISSN 1024-1221 R&D Projects: GA ČR(CZ) GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : bismuth coordination polymer * tartrate ligand * thermal decomposition * alpha-Bi 2 O 3 nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.565, year: 2016

  2. 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...

  3. Thermal decomposition studies of the polyhedral oligomeric silsesquioxane, POSS h, and when it is impregnated with the metallocene bis(η 5-cyclopentadienyl)zirconium (IV) dichloride or immobilized on silica

    Science.gov (United States)

    Bianchini, D.; Butler, I. S.; Barsan, M. M.; Martens, W.; Frost, R. L.; Galland, G. B.; dos Santos, J. H. Z.

    2008-11-01

    Thermal decomposition studies of the free polyhedral oligomeric silsesquioxane, POSS h, and when this compound has been impregnated with Cp 2ZrCl 2 (Cp = η 5-C 5H 5) or immobilized on SiO 2 were conducted using infrared emission spectroscopy (IES) over a 100-1000 °C temperature range and by thermogravimetric analysis (TGA). The organic groups in POSS h apparently decompose thermally into Si-CH 3, Si-H and other fragments. Upon impregnation with Cp 2ZrCl 2, however, a different thermal decomposition pathway was followed and new infrared emission bands appeared in the 1000-900 cm -1 region suggesting the formation of Si-O-Zr moieties. When immobilized on SiO 2 and subjected to thermal decomposition, the POSS h compound lost its organic groups and the inorganic structure remaining was incorporated into the SiO 2 framework.

  4. Kinetics of the Thermal Decomposition of Tetramethylsilane behind the Reflected Shock Waves in a Single Pulse Shock Tube (SPST) and Modeling Study

    Science.gov (United States)

    Parandaman, A.; Sudhakar, G.; Rajakumar, B.

    Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.

  5. Synthesis and character investigation of new collagen Hydrolysate/polyvinyl alcohol/hydroxyapatite Polymer-Nano-Porous Membranes: I. Experimental design optimization in thermal and structural properties.

    Science.gov (United States)

    Imanieh, Hossein; Aghahosseini, Hamideh

    2013-12-01

    Development of bioorganic-inorganic composites has drawn eyes to extensive attention in biomedical fields and tissue engineering. So many attempts to prepare hydroxyapatite (HA), in conjunction with various binders including polyvinyl alcohol (PVA), and collagen has performed for late 20 years. We applied a method based on the phase separation for making of polymer porous membranes. This procedure is induced through the addition of a small quantity of water (polymer-rich phase) to a solution with HA precursors (polymer-poor phase). Thermal and structural composite properties of collagen Hydrolysate (CH)-PVA/HA Polymer-Nano-Porous Membranes were analyzed by Design of experiment that was undertaken using D-optimal approach, to select the optimal combination of nano composites precursor. The resulted composite characters were investigated by Fourier transform infrared, scanning electron microscopy (SEM) and thermal gravimetric analysis. Based on the SEM images, this new method could be clearly concluded to porous CH-PVA/HA hybrid materials. Finally the hemocompatibility of nanocomposite membranes were evaluated by the hemolysis study.

  6. Tris dithiocarbamate of Co(III) complexes: Synthesis, characterization, thermal decomposition studies and experimental and theoretical studies on their crystal structures

    Science.gov (United States)

    Sonia, Ayyavoo Sait; Bhaskaran, Ramalingam

    2017-04-01

    New homoleptic complexes of the form [Co(L1)3] & [Co(L2)3] where L1 = (ethylaminoethanol dithiocarbamate) 1 and L2 = (methylaminoethanol dithiocarbamate) 2 have been prepared and characterized by elemental analysis, IR, UV-visible absorption spectra, Cyclic voltammetry,1H and C13 NMR. The thermal properties were studied using a simultaneous thermal analyzer, and showed two main steps of decomposition. In addition, structures for 1 and 2 have been elucidated by X-ray crystallography. The single-crystal X-ray analysis for both the complexes showed distorted octahedral geometry. The optimized molecular structure, natural bond orbital analysis, electrostatic potential map, HOMO-LUMO energies, molecular properties, and atomic charges of these molecules have been studied by performing DFT/B3LYP/6-31G(d,p) level of theory in gas phase.

  7. Believable Characters

    Science.gov (United States)

    El-Nasr, Magy Seif; Bishko, Leslie; Zammitto, Veronica; Nixon, Michael; Vasiliakos, Athanasios V.; Wei, Huaxin

    The interactive entertainment industry is one of the fastest growing industries in the world. In 1996, the U.S. entertainment software industry reported 2.6 billion in sales revenue, this figure has more than tripled in 2007 yielding 9.5 billion in revenues [1]. In addition, gamers, the target market for interactive entertainment products, are now reaching beyond the traditional 8-34 year old male to include women, Hispanics, and African Americans [2]. This trend has been observed in several markets, including Japan, China, Korea, and India, who has just published their first international AAA title (defined as high quality games with high budget), a 3D third person action game: Ghajini - The Game [3]. The topic of believable characters is becoming a central issue when designing and developing games for today's game industry. While narrative and character were considered secondary to game mechanics, games are currently evolving to integrate characters, narrative, and drama as part of their design. One can see this pattern through the emergence of games like Assassin's Creed (published by Ubisoft 2008), Hotel Dusk (published by Nintendo 2007), and Prince of Persia series (published by Ubisoft), which emphasized character and narrative as part of their design.

  8. Optimal Thermolysis Conditions for Soil Carbon Storage on Plant Residue Burning: Modeling the Trade-Off between Thermal Decomposition and Subsequent Biodegradation.

    Science.gov (United States)

    Kajiura, Masako; Wagai, Rota; Hayashi, Kentaro

    2015-01-01

    Field burning of plant biomass is a widespread practice that provides charred materials to soils. Its impact on soil C sequestration remains unclear due to the heterogeneity of burning products and difficulty in monitoring the material's biodegradation in fields. Basic information is needed on the relationship between burning conditions and the resulting quantity/quality of residue-derived C altered by thermal decomposition and biodegradation. In this study, we thermolyzed residues (rice straw and husk) at different temperatures (200-600°C) under two oxygen availability conditions and measured thermal mass loss, C compositional change by solid-state C NMR spectroscopy, and biodegradability of the thermally altered residues by laboratory aerobic incubation. A trade-off existed between thermal and microbial decomposition: when burned at higher temperatures, residues experience a greater mass loss but become more recalcitrant via carbonization. When an empirical model accounting for the observed trade-off was projected over 10 to 10 yr, we identified the threshold temperature range (330-400°C) above and below which remaining residue C is strongly reduced. This temperature range corresponded to the major loss of O-alkyl C and increase in aromatic C. The O/C molar ratios of the resultant residues decreased to 0.2 to 0.4, comparable to those of chars in fire-prone field soils reported previously. Although the negative impacts of biomass burning need to be accounted for, the observed relationship may help to assess the long-term fate of burning-derived C and to enhance soil C sequestration. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  9. Studies on the thermal decomposition of nitrates found in highly active waste and of chemicals used to convert the waste to glass

    International Nuclear Information System (INIS)

    Chun, K.S.

    1977-05-01

    The decomposition of all the individual chemicals used in the Harwell inactive vitrification pilot plant has been studied by means of a thermal balance. Weight loss curves to 1100 0 C have been obtained. The four materials sodium nitrate, cesium nitrate, lithium nitrate and ruthenium nitroso-nitrate (solution) showed a greater weight loss than that based on an oxide yield, and hence these compounds or their products of decomposition are volatile below 1100 0 C. The remaining materials suffered a weight loss no more than that corresponding to a full yield of the oxide, and hence they were not volatile below 1100 0 C. Most of the chemicals begin to decompose at less than 75 0 C but the nitrates of cesium, strontium, barium and sodium not until 295 0 to 590 0 C. The results obtained can be used in the analysis of process conditions in the vitrification and calcination of highly radioactive wastes and also of the thermal decomposition behaviour of mixtures containing those materials. The materials tested were: Al(NO 3 ) 3 .9H 2 O, Ba(NO 3 ) 2 , CaNo 3 , Cr(NO 3 ) 3 .9H 2 O, Fe(NO 3 ) 3 .9H 2 O. Mg(NO 3 ) 2 .6H 2 O, Ni(NO 3 ) 2 .6H 2 O, R.E. Nitrates, Ruthenium Solution, Sr(NO 3 ) 2 , UO 2 (NO 3 ) 2 .6H 2 O, Zn(NO 3 ) 2 .6H 2 O. Zirconium Solution, 'Gasil WP' Silica, 'Neosyl' Silica, LiOH.H 2 O. LiNO 3 .3H 2 O, Na 2 CO 3 , NaNO 3 , Na 2 B 4 O 7 .10H 2 O. (author)

  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. Foam-like, microstructural SnO2-carbon composite thin films synthesized via a polyol-assisted thermal decomposition method.

    Science.gov (United States)

    Ng, See-How; Chew, Sau-Yen; Wang, Jia-Zhao; Chen, Jun; Dou, Shi-Xue; Liu, Hua-Kun

    2009-01-28

    Foam-like, microstructural SnO2-carbon composite thin films were synthesized by refluxing SnCl2.2H2O in ethylene glycol (EG) at 195 degrees C for 4 h under vigorous stirring in air followed by thermal decomposition of the as-synthesized precursor solution, whereby the products were deposited onto stainless steel (SS) substrates. Subsequently, the decomposed product, which now consists only of the microstructural SnO2-carbon composite thin film, without the addition of any binder and carbon black conductive agent, was directly applied as an anode material for use in a Li-ion rechargeable battery. Physical and electrochemical characterizations of the as-synthesized thin films were carried out. The foam-like, microstructural SnO2-carbon composite thin films that undergo thermal decomposition in air at 300 degrees C demonstrated the best cyclability, delivering a specific discharge capacity of approximately 496 mAh g(-1) beyond 100 cycles. We believe that the presence of a uniform, SnO2-carbon network throughout the foam-like thin film, acts not only as an improved conducting network but also buffered the volume expansion upon Li-Sn alloying, resulting in a much improved cycling of the composite thin film electrode.

  12. 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.

  13. 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.

  14. Thermal Conductivity of the Iron-Based Superconductor FeSe: Nodeless Gap with a Strong Two-Band Character.

    Science.gov (United States)

    Bourgeois-Hope, P; Chi, S; Bonn, D A; Liang, R; Hardy, W N; Wolf, T; Meingast, C; Doiron-Leyraud, N; Taillefer, Louis

    2016-08-26

    The thermal conductivity κ of the iron-based superconductor FeSe was measured at temperatures down to 75 mK in magnetic fields up to 17 T. In a zero magnetic field, the electronic residual linear term in the T=0  K limit, κ_{0}/T, is vanishingly small. The application of a magnetic field B causes an exponential increase in κ_{0}/T initially. Those two observations show that there are no zero-energy quasiparticles that carry heat and therefore no nodes in the superconducting gap of FeSe. The full field dependence of κ_{0}/T has the classic two-step shape of a two-band superconductor: a first rise at very low field, with a characteristic field B^{⋆}≪B_{c2}, and then a second rise up to the upper critical field B_{c2}. This shows that the superconducting gap is very small (but finite) on one of the pockets in the Fermi surface of FeSe. We estimate that the minimum value of the gap, Δ_{min}, is an order of magnitude smaller than the maximum value, Δ_{max}.

  15. Researching on thermal characters in Yb3+/Er3+ codoped phosphate glass ceramic for fluorescence temperature sensor

    Directory of Open Access Journals (Sweden)

    Yuanxue Cai

    Full Text Available To explore fluorescence temperature sensor, Yb3+/Er3+ co-doped phosphate glass ceramic was prepared by high-temperature melting method and thermal annealing technology. The luminescent spectra of the sample were measured under 975 nm excitation at the temperature ranges of 25–300 °C. The strong green up-conversion emissions, coming from the transitions of Er3+ ion: 2H11/2-4I15/2 and 4S3/2-4I15/2, were observed. The fluorescence intensity ratio of the two green up-conversion emissions can change with the increasing of temperature. The sensitivity of Er3+/Yb3+ co-doped phosphate glass ceramic reached the maximal value of ∼0.0077 K−1. The sensitivity is relatively flat at the high temperature region. Our research is valuable to developing fluorescence temperature sensor. Keywords: Luminescence, Optical materials and properties, Sensor

  16. 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.

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

    International Nuclear Information System (INIS)

    Herrera, Adriana P.; Polo-Corrales, Liliana; Chavez, Ermides; Cabarcas-Bolivar, Jari; Uwakweh, Oswald N.C.; Rinaldi, Carlos

    2013-01-01

    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 χ′and out-of-phase χ″ components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for nanoparticles

  18. Combustion of Organic Molecules by the Thermal Decomposition of Perchlorate Salts: Implications for Organics at the Mars Phoenix Scout Landing Site

    Science.gov (United States)

    Ming, D.W.; Morris, R.V.; Niles, B.; Lauer, H.V.; Archer, P.D.; Sutter, B.; Boynton, W.V.; Golden, D.C.

    2009-01-01

    The Mars 2007 Phoenix Scout Mission successfully landed on May 25, 2008 and operated on the northern plains of Mars for 150 sols. The primary mission objective was to study the history of water and evaluate the potential for past and present habitability in Martian arctic ice-rich soil [1]. Phoenix landed near 68 N latitude on polygonal terrain created by ice layers that are a few centimeters under loose soil materials. The Phoenix Mission is assessing the potential for habitability by searching for organic molecules in the ice or icy soils at the landing site. Organic molecules are necessary building blocks for life, although their presence in the ice or soil does not indicate life itself. Phoenix searched for organic molecules by heating soil/ice samples in the Thermal and Evolved-Gas Analyzer (TEGA, [2]). TEGA consists of 8 differential scanning calorimeter (DSC) ovens integrated with a magnetic-sector mass spectrometer with a mass range of 2-140 daltons [2]. Endothermic and exothermic reactions are recorded by the TEGA DSC as samples are heated from ambient to 1000 C. Evolved gases, including any organic molecules and their fragments, are simultaneously measured by the mass spectrometer during heating. Phoenix TEGA data are still under analysis; however, no organic fragments have been identified to date in the evolved gas analysis (EGA). The MECA Wet Chemistry Lab (WCL) discovered a perchlorate salt in the Phoenix soils and a mass 32 peak evolved between 325 and 625 C for one surface sample dubbed Baby Bear [3]. The mass 32 peak is attributed to evolved O2 generated during the thermal decomposition of the perchlorate salt. Perchlorates are very strong oxidizers when heated, so it is possible that organic fragments evolved in the temperature range of 300-600 C were combusted by the O2 released during the thermal decomposition of the perchlorate salt. The byproduct of the combustion of organic molecules is CO2. There is a prominent release of CO2 between 200

  19. 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.

  20. Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4Hydrogen Storage Composite.

    Science.gov (United States)

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

    2017-09-20

    The lightweight compound material NaNH 2 -NaBH 4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH 2 -NaBH 4 (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 H 2 , NH 3 , B 2 H 6 , and N 2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B 6 H 12 also exists. The TG/DTA analyses show that the composite NaNH 2 -NaBH 4 (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) Na 3 (NH 2 ) 2 BH 4 hydride decomposes into Na 3 BN 2 and H 2 (200-350 °C); (2) remaining Na 3 (NH 2 ) 2 BH 4 reacts with NaBH 4 and Na 3 BN 2 , generating Na, BN, NH 3 , N 2 , and H 2 (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.

  1. Holistic Processing of Chinese Characters

    Directory of Open Access Journals (Sweden)

    Alan Chun-Nang Wong

    2011-05-01

    Full Text Available Enhanced holistic processing (obligatory attention to all parts of an object has been associated with different types of perceptual expertise involving faces, cars, fingerprints, musical notes, English words, etc. Curiously Chinese characters are regarded as an exception, as indicated by the lack of holistic processing found for experts (Hsiao and Cottrell, 2009. The ceiling performance of experts, however, may have caused this null effect. We revisit this issue by adopting the often-used face-composite sequential-matching task to two-part Chinese characters. Participants matched the target halves (left or right of two characters while ignoring the irrelevant halves. Both Chinese readers (experts and non-Chinese readers (novices showed holistic processing. Follow-up experiments suggested different origins of the effects for the two groups. For experts, holistic processing was sensitive to the amount of experience with the characters, as it was larger for words than non-words (formed by swapping the two parts of a valid character. Novices, however, showed similar degree of holistic processing to words and non-words, suggesting that their effects were more related to their inefficient decomposition of a complex, character-like pattern into parts. Overall these findings suggest that holistic processing may be a marker of expertise with Chinese characters, contrary to previous claims.

  2. Mass-dependent and Mass-independent Sulphur Isotope Fractionation Accompanying Thermal- and Photo-chemical Decomposition of Sulphur Bearing Organic Compounds

    Science.gov (United States)

    Oduro, Harry; Izon, Gareth; Ono, Shuhei

    2014-05-01

    The bimodal S-isotope record, specifically the transition from mass independent (MIF) to mass dependent fractionation (MDF), is perhaps the most widely cited line of evidence for an irreversible rise in atmospheric oxygen at ca. 2.4Ga. The production and preservation of S-MIF, manifested in both Δ33S and Δ36S, within the geological record are linked to atmospheric O2 via a number of arguments. However, to date, the only mechanism capable of generating S-MIF consistent with the Archaean sedimentary records involves gas-phase ultraviolet irradiation of SO21 photolysis. More recently, Δ33S S-MIF trends have been reported from en vitro thermochemical sulphate reduction (TSR) experiments, prompting authors to question the importance of S-MIF as a proxy for Earth oxidation2. Importantly, whilst emerging TSR experiments3,4 affirm the reported Δ33S trends2, these experiments fail to identify correlated S-MIF between Δ33S and Δ36S values3,4. Realization that S-MIF is confined to Δ33S during TSR, precludes TSR as a mechanism responsible for the origin of the Archaean S-MIF record but strongly suggests the effect originating from a magnetic isotope effect (MIE) associated with 33S nucleus3,4. Clearly, photochemical and thermochemical processes impart different Δ36S/Δ33S trends with significant variation in δ34S; however, a complete experimental elucidation of mechanisms responsible for the S-MIF and S-MIE signatures is lacking. Interestingly, a complete understanding of the S-isotope chemistry during thermal- and photo-chemical decomposition may reveal wavelength and thermal dependence archived in the sedimentary record. Here we extend the experimental database to explore the magnitude and sign of Δ36S/Δ33S and δ34S produced during both photo- and thermochemical processes. Here the organic sulphur compounds (OSC) utilized in these experiments carries diagnostic Δ36S/Δ33S patterns that differ from those reported from photolysis experiment SO2 and from the

  3. Effect of thermal effluents from the Savannah River Plant on leaf decomposition rates in onsite creeks and the Savannah River

    International Nuclear Information System (INIS)

    Sadowski, P.W.; Matthews, R.A.

    1986-06-01

    Sweet gum and sycamore leaf packs were packs were placed in a thermally stressed, a post-thermal, and an ambient stream located on the Savannah River Plant, South Carolina, and in the Savannah River below the mouth of each stream. Processing rates for the leaf packs were determined over a 77-day period from December 1982 to March 1983. Due to inundation of the sampling sites by river flooding, temperatures in the stream receiving thermal effluent were reduced after day 24. Sweet gum leaves decomposed considerably faster than did sycamore leaves, particularly in the thermal creek. An exponential decay model was used to demonstrate significant differences in loss of ash-free dry weight from leaf packs in thermally stressed and nonthermal creeks. Differences in leaf processing rates between creek sites were greatest during periods of therma stress. Within each leaf species, leaf processing rates were not significantly different between nonthermal sites, nor between sites in the Savannah River

  4. 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 s...

  5. The effect of Al on thermal stability and kinetics of decomposition of MgH{sub 2} prepared by mechanochemical reaction at different conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ershova, O.G.; Dobrovolsky, V.D., E-mail: dobersh@ipms.kiev.ua; Solonin, Y.M.; Khyzhun, O.Y.; Koval, A.Y.

    2015-07-15

    This work is directed at decreasing decomposition temperature of MgH{sub 2}. In accordance with the theoretical predictions, hydride of solid solution of Al in Mg should decompose at lower temperature compared to that of MgH{sub 2}, and numerous experiments indicate that thermodynamic stability of the hydride depends on methods and conditions of its synthesis. Therefore, the goal of this article is to study the possibility of obtaining the hydride of solid solution of aluminum in magnesium by different technological approaches. Three mechanical composite alloys derived by the different approaches are studied employing the X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermodesorption spectroscopy (TDS) methods. XRD Rietveld analysis reveals that the hydrogenation of a Mg + 10 wt% Al powder by means of reactive milling in the hydrogen atmosphere as well as hydrogenation of the powder from the gaseous phase after milling the powder for 20 h in the argon atmosphere leads to formation of aluminum-free MgH{sub 2} hydride and the Mg{sub 17}Al{sub 12} phase. Our TDS studies (at P{sub H2} = 0.1 MPa) indicate that additives of 10 wt% Al to magnesium do not lead to decreasing the decomposition temperature of MgH{sub 2} prepared by mechanochemical reaction at the different conditions. - Highlights: • Three mechanical alloys with 10% wt. Al additives to Mg have been synthesized. • Hydrogen-sorption properties and thermal stability of the alloys are studied at 1 bar H{sub 2}. • Al additives to Mg do not influence decomposition temperature of MgH{sub 2} phase of the alloys. • Al additives do not improve kinetics of process of hydrogen desorption from MgH{sub 2} phase.

  6. 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.

  7. 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.

  8. Synthesis and characterization of nanosized MgxMn1-xFe2O4 ferrites by both sol-gel and thermal decomposition methods

    Science.gov (United States)

    De-León-Prado, Laura Elena; Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina; Hurtado-López, Gilberto Francisco

    2017-04-01

    This work reports the synthesis of MgxMn1-xFe2O4 (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.

  9. Preparation of CoFeO Nanocrystallites by Solvothermal Process and Its Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

    Directory of Open Access Journals (Sweden)

    Shusen Zhao

    2010-01-01

    Full Text Available Nanometer cobalt ferrite (CoFe2O4 was synthesized by polyol-medium solvothermal method and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and selected area electron diffraction (SAED. Further, the catalytic activity and kinetic parameters of CoFe2O4 nanocrystallites on the thermal decomposition behavior of ammonium perchlorate (AP have been investigated by thermogravimetry and differential scanning calorimetry analysis (TG-DSC. The results imply that the catalytic performance of CoFe2O4 nanocrystallites is significant and the decrease in the activation energy and the increase in the rate constant for AP further confirm the enhancement in catalytic activity of CoFe2O4 nanocrystallites. A mechanism based on an proton transfer process has also been proposed for AP in the presence of CoFe2O4 nanocrystallites.

  10. A novel thermal decomposition approach to synthesize hydroxyapatite-silver nanocomposites and their antibacterial action against GFP-expressing antibiotic resistant E. coli.

    Science.gov (United States)

    Sahni, Geetika; Gopinath, P; Jeevanandam, P

    2013-03-01

    A novel thermal decomposition approach to synthesize hydroxyapatite-silver (Hap-Ag) nanocomposites has been reported. The nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and diffuse reflectance spectroscopy techniques. Antibacterial activity studies for the nanocomposites were explored using a new rapid access method employing recombinant green fluorescent protein (GFP) expressing antibiotic resistant Escherichia coli (E. coli). The antibacterial activity was studied by visual turbidity analysis, optical density analysis, fluorescence spectroscopy and microscopy. The mechanism of bactericidal action of the nanocomposites on E. coli was investigated using atomic force microscopy, and TEM analysis. Excellent bactericidal activity at low concentration of the nanocomposites was observed which may allow their use in the production of microbial contamination free prosthetics. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Thermal and IR spectroscopic study of double sulfate (NH4)4Ce(SO4)4x2H2O

    International Nuclear Information System (INIS)

    Bondar', S.A.; Mikhajlova, N.L.; Popova, R.A.; Nikitina, S.D.

    1986-01-01

    Results of thermal investigation of ammonium and cerium (4) double sulfate, prepared under equilibrium conditions in system (NH 4 ) 2 SO 4 -Ce(SO 4 ) 2 -H 2 SO 4 -H 2 O at 100 deg C in the concentration range 20-40 mass% H 2 SO 4 and mole ratio (NH 4 ) 2 SO 4 :Ce(SO 4 ) 2 =2:1, are presented. The character of thermal decomposition is confirmed by IR spectroscopy method. At and intermediate stage of thermal decomposition ammonium and cerium (3) double sulfate, then Ce 2 (SO 4 ) 3 are formed, the decomposition of the latter results in the formation of cerium dioxide

  12. Thermal Co-Decomposition of Silver Acetylacetonate and Tin (II) Hexafluoroacetylacetonate: Formation of Carbonaceous Ag/AgxSn(x=4 and 6.7)/SnO2 Composites

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Duchek, P.; Urbanová, Markéta; Pokorná, Dana; Bezdička, Petr; Jakubec, Ivo; Pola, M.; Čerstvý, R.; Kovářík, T.; Galíková, Anna; Pola, Josef

    2013-01-01

    Roč. 566, AUG 20 (2013), s. 92-99 ISSN 0040-6031 Grant - others:GA MŠK(CZ) CZ1.05/2.1.00/03.0088 Institutional support: RVO:67985858 ; RVO:61388980 Keywords : co-decomposition * thermal gravimetric analysis * Ag-Sn intermetallic compounds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.105, year: 2013

  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...... 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......-connected planar graph contains two edge-disjoint 18/19 -thin spanning trees. Finally, we make progress on a conjecture by Baudon, Bensmail, Przybyło, and Wozniak stating that if a graph can be decomposed into locally irregular graphs, then there exists such a decomposition with at most 3 parts. We show...

  14. 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.

  15. Effect of thermal treatment and frozen storage on lipid decomposition of light and dark muscles of saithe (Pollachius virens).

    Science.gov (United States)

    Karlsdottir, Magnea G; Sveinsdottir, Kolbrun; Kristinsson, Hordur G; Villot, Dominique; Craft, Brian D; Arason, Sigurjon

    2014-12-01

    Lipid decomposition of saithe (Pollachius virens) light and dark muscles was monitored during frozen storage at -25°C of raw (up to 18 months) and cooked products. Samples were cooked after 0, 6 and 12 months raw storage then refrozen and stored at -25°C for 12 months to determine the stability of cooked-then-stored samples. Fatty acid profiles, formation of hydroperoxides (PV), thiobarbituric acid reactive substances (TBARS), fluorescence compounds (OFR) and free fatty acids (FFA) were evaluated throughout the storage for all samples. In general, results indicated that enzymatic lipolysis was the driving factor influencing the quality of saithe over raw storage and it mostly affected polyunsaturated lipids in the light muscle. Cooking, however, inhibited FFA formation and induced formation of PV and TBARS. This behavior was more evident in samples cooked after long raw storage periods. The initial quality of the raw material before cooking is therefore critical with regard to oxidative stability of cooked fish products. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Thermal decomposition of sewage sludge under N2, CO2and air: Gas characterization and kinetic analysis.

    Science.gov (United States)

    Hernández, Ana Belén; Okonta, Felix; Freeman, Ntuli

    2017-07-01

    Thermochemical valorisation processes that allow energy to be recovered from sewage sludge, such as pyrolysis and gasification, have demonstrated great potential as convenient alternatives to conventional sewage sludge disposal technologies. Moreover, these processes may benefit from CO 2 recycling. Today, the scaling up of these technologies requires an advanced knowledge of the reactivity of sewage sludge and the characteristics of the products, specific to the thermochemical process. In this study the behaviour of sewage sludge during thermochemical conversion, under different atmospheres (N 2 , CO 2 and air), was studied, using TGA-FTIR, in order to understand the effects of different atmospheric gases on the kinetics of degradation and on the gaseous products. The different steps observed during the solid degradation were related with the production of different gaseous compounds. A higher oxidative degree of the atmosphere surrounding the sample resulted in higher reaction rates and a shift of the degradation mechanisms to lower temperatures, especially for the mechanisms taking place at temperatures above 400 °C. Finally, a multiple first-order reaction model was proposed to compare the kinetic parameters obtained under different atmospheres. Overall, the highest activation energies were obtained for combustion. This work proves that CO 2 , an intermediate oxidative atmosphere between N 2 and air, results in an intermediate behaviour (intermediate peaks in the derivative thermogravimetric curves and intermediate activation energies) during the thermochemical decomposition of sewage sludge. Overall, it can be concluded that the kinetics of these different processes require a different approach for their scaling up and specific consideration of their characteristic reaction temperatures and rates should be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 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.

  18. Thermal co-decomposition of silver acetylacetonate and tin(II) hexafluoroacetylacetonate: Formation of carbonaceous Ag/Ag{sub x}Sn(x = 4 and 6.7)/SnO{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Křenek, T.; Duchek, P. [Research Centre of New Technologies, University of West Bohemia, 30614 Plzeň (Czech Republic); Urbanová, M.; Pokorná, D. [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR v.v.i., 16502 Prague (Czech Republic); Bezdička, P.; Jakubec, I. [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic); Pola, M.; Čerstvý, R.; Kovářík, T. [Research Centre of New Technologies, University of West Bohemia, 30614 Plzeň (Czech Republic); Galiková, A. [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic); Pola, J., E-mail: pola@icpf.cas.cz [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic)

    2013-08-20

    Highlights: • Ag acetylacetonate increases thermal stability by mixing with Sn hexafluoroacetylacetonate. • Heated mixture of chelates yields a residue containing Ag, Sn, O and C elements. • Residues obtained at higher temperature contain Ag–Sn intermetallic compounds. - Abstract: Thermal co-decomposition of silver(I) acetylacetonate and tin(II) hexafluoroacetylacetonate has been examined by using thermal gravimetry, differential scanning calorimetry and complementary analyses of gaseous products and solid residues by Fourier transform infrared and Raman spectroscopy, X-ray diffraction and scanning electron microscopy. It is revealed that poorly stable silver(I) acetylacetonate mixed with tin(II) hexafluoroacetylacetonate does not undergo thermal decomposition at around 120 °C, but takes part in a room-temperature solid-state interaction with the Sn counterpart, which is ensued by an exothermal process at 109 °C and subsequent co-decomposition involving a pronounced stage at around 275 °C. All steps lead to carbonaceous Ag/SnO{sub 2} composites containing crystalline Ag at 200 °C, Ag and SnO{sub 2} at 400 °C, and Ag, SnO{sub 2}, Ag{sub 4}Sn and Ag{sub 6.7}Sn at 600 °C. The intermetallic Ag{sub 6.7}Sn compound is judged to arise from nanostructured environment of alloying Ag and Sn.

  19. 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.

  20. Structural and Thermal Characterization of Zolpidem Hemitartrate Hemihydrate (Form E) and Its Decomposition Products by Laboratory X-Ray Powder Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Halasz, I.; Dinnebier, R

    2010-01-01

    The crystal structure of zolpidem hemitartrate hemihydrate (I, Form E) has been solved from high-resolution laboratory powder diffraction data. It crystallizes in the orthorhombic P2{sub 1}2{sub 1}2{sub 1} space group with a = 22.4664(6) {angstrom}, b = 26.0420(7) {angstrom}, and c = 7.4391(1) {angstrom}. Protonation of zolpidem molecules could not be unambiguously determined. Thermal stability of Form E has been investigated by TG-DTA and in situ by temperature resolved X-ray powder diffraction. Water loss occurs between 50 C {le} t {le} 100 C while structure decomposition commences at approximately 120 C yielding zolpidem tartrate (II) and pure zolpidem base (III) in approximately equimolar amounts. Crystal structures of II and III have been solved simultaneously from a single powder pattern of thermally decomposed I. Zolpidem tartrate crystallizes in the orthorhombic P2{sub 1}2{sub 1}2{sub 1} space group with a = 19.9278(8) {angstrom}, b = 15.1345(8) {angstrom}, and c = 7.6246(2) {angstrom} (at 140 C). Zolpidem base crystallizes in the orthorhombic Pcab space group with a = 9.9296(4) {angstrom}, b = 18.4412(9) {angstrom}, and c = 18.6807(9) {angstrom} (at 140 C). In the reported crystal structures zolpidem molecules form stacks through {pi}-{pi} interaction or dipole-dipole interactions while tartrate moieties, if present, form hydrogen bonded chains. Water molecule in I forms a hydrogen bond to the imidazole nitrogen atom of the zolpidem molecule. Free space in the crystal structure of I could allow for the additional water molecules and thus a variable water content.

  1. Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

    Science.gov (United States)

    Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

    2016-11-01

    We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

  2. Synthesis, crystal structure and thermal decomposition mechanism of the complex [Sm(p-BrBA)3bipy.H2O]2.H2O

    International Nuclear Information System (INIS)

    Zhang Haiyan; Zhang Jianjun; Ren Ning; Xu Suling; Tian Liang; Bai Jihai

    2008-01-01

    A new binuclear samarium (III) complex [Sm(p-BrBA) 3 bipy.H 2 O] 2 .H 2 O (p-BrBA = p-bromobenzoic acid; bipy = 2,2'-bipyridine) has been synthesized and characterized by elemental analysis, UV, IR, molar conductance and TG-DTG techniques. The structure of the complex was established by single crystal X-ray diffraction. It crystallizes in triclinic, space group P1-bar with a = 8.2476(7) A, b = 13.3483(10) A, c = 15.9035(13) A, α 73.9160(10) o , β = 78.9630(10) o , γ = 74.4770(10) o , Z = 1, D c 1.947 g cm -3 , F(000) = 910. The carboxylic groups are bonded to the samarium ion in two modes: bidentate bridging, monodentate. Each center Sm 3+ ion is eight-coordinated by one 2,2'-bipyridine molecular, four bidentate bridging and a monodentate carboxylic group, as well as one water molecular. The coordination polyhedron around each Sm 3+ ion can be described as bi-capped triangular prism geometry. The thermal decomposition behavior of the title complex in a static air atmosphere was investigated by TG-DTG and IR techniques

  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. Thermochemical cycles for energy storage: Thermal decomposition of ZnCO{sub 4} systems. Final topical report, January 1, 1982--December 31, 1984

    Energy Technology Data Exchange (ETDEWEB)

    Wentworth, W.E. [Houston Univ., TX (United States)

    1992-04-01

    The overall objective of our research has been to develop thermochemical cycles that can be used for energy storage. A specific cycle involving ammonium hydrogen sulfate (NH{sub 4}HSO{sub 4}) has been proposed. Each reaction in the proposed cycle has been examined experimentally. Emphasis has been placed on the basic chemistry of these reactions. In the concluding phase of this research, reported herein, we have shown that when NH{sub 4}HSO{sub 4} is mixed with ZnO and decomposed, the resulting products can be released stepwise (H{sub 2}A{sub (g)} at {approximately}163{degrees}C, NH{sub 3(g)} at 365--418{degrees}C, and a mixture of SO{sub 2(g)} and SO{sub 3(g)} at {approximately}900{degrees}C) and separated by controlling the reaction temperature. Side reactions do not appear to be significant and the respective yields are high as would be required for the successful use of this energy storage reaction in the proposed cycle. Thermodynamic, kinetic, and other reaction parameters have been measured for the various steps of the reaction. Finally we have completed a detailed investigation of one particular reaction: the thermal decomposition of zinc sulfate (ZnSO{sub 4}). We have demonstrated that this reaction can be accelerated and the temperature required reduced by the addition of excess ZnO, V{sub 2}A{sub 5} and possibly other metal oxides.

  6. Superparamagnetism and spin-glass like state for the MnFe2O4 nano-particles synthesized by the thermal decomposition method

    International Nuclear Information System (INIS)

    Gao Ruorui; Zhang Yue; Yu Wei; Xiong Rui; Shi Jing

    2012-01-01

    MnFe 2 O 4 nano-particles with an average size of about 7 nm were synthesized by the thermal decomposition method. Based on the magnetic hysteresis loops measured at different temperatures the temperature-dependent saturation magnetization (M S ) and coercivity (H C ) are determined. It is shown that above 20 K the temperature-dependence of the M S and H C indicates the magnetic behaviors in the single-domain nano-particles, while below 20 K, the change of the M S and H C indicates the freezing of the spin-glass like state on the surfaces. By measuring the magnetization–temperature (M–T) curves under the zero-field-cooling (ZFC) and field-cooling procedures at different applied fields, superparamagnetism behavior is also studied. Even though in the ZFC M–T curves peaks can be observed below 160 K, superparamagnetism does not appear until the temperature goes above 300 K, which is related with the strong inter-particle interaction. - Highlights: ► MnFe 2 O 4 nano-particles with size of 7 nm were prepared. ► The surface spin-glass like state is frozen below 20 K. ► The peaks in ZFC magnetization–temperature curves are observed below 160 K. ► The inter-particle interaction inhibits the superparamagnetism at room temperature.

  7. 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.

  8. 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.

  9. A Simple Thermal Decomposition Method for Synthesis of Co0.6Zn0.4Fe2O4 Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ibrahim Sharifi

    2016-12-01

    Full Text Available Magnetic nanoparticles attracted a great deal of attention in the medical applications due to their unique properties. The most exceptional property of magnetic particles is their response to a magnetic force, and this property has been utilized in applications such as drug targeting, bioseparation, contrast agents in magnetic resonance imaging (MRI and heating mediators for cancer therapy. In this study, a ternary system of Co0.4Zn0.6Fe2O4 was synthesized by thermal decomposition method using metal acetylacetonate in high temperature boiling point solvent and fatty acids. Unlike other synthesis techniques this method can be get nearly monodispersed nanoparticles that makes them suitable for medical applications like hyperthermia. X-ray diffraction study was used to determine phase purity, crystal structure, and average crystallite size of cobalt-zinc ferrite nanoparticles. The average diameter of particles was determined by field emission scanning electron microscope (FESEM around 16 nm. Fourier transform infrared (FT-IR measurement confirmed mono phase spinel structure of ferrite. The as-prepared ferrite nanoparticles were characterized extensively by other analytic techniques like vibrating sample magnetometer (VSM to achieve magnetic properties of nanoparticles. Room temperature magnetization measurements showed the magnetization Ms and coercivity of magnetic nanoparticles as high as 74 emu/g and 114 Oe, which can be a good candidate for use in hyperthermia applications.

  10. Simple cerium-triethanolamine complex: Synthesis, characterization, thermal decomposition and its application to prepare ceria support for platinum catalysts used in methane steam reforming

    Science.gov (United States)

    Wattanathana, Worawat; Nootsuwan, Nollapan; Veranitisagul, Chatchai; Koonsaeng, Nattamon; Laosiripojana, Navadol; Laobuthee, Apirat

    2015-06-01

    Cerium-triethanolamine complex was synthesized by simple complexation method in 1-propanol solvent using cerium(III) chloride as a metal source and triethanolamine as a ligand. The structures of the prepared complex were proposed based on FT-IR, FT-Raman and ESI-MS results as equimolar of triethanolamine and cerium chelated complex having monomeric tricyclic structure with and without chloride anion as another coordinating group known as ceratrane. The complex was used as a precursor for ceria material done by thermal decomposition. XRD result revealed that when calcined at 600 °C for 2 h, the cerium complex was totally turned into pure ceria with cubic fluorite structure. The obtained ceria was then employed to synthesize platinum doped ceria catalysts for methane steam reforming. Various amounts of platinum i.e. 1, 3, 5 and 10 mol percents were introduced on the ceria support by microwave-assisted wetness impregnation using ammonium tetrachloroplatinate(II). The platinum-impregnated ceria powders were subjected to calcination in 10% hydrogen/helium atmosphere at 500 °C for 3 h to reduce platinum(II) to platinum(0). XRD patterns of the catalysts confirmed that the platinum particles doped on the ceria support were in the form of platinum(0). Catalytic activity test showed that the catalytic activities got higher as the amounts of platinum doped increased. Besides, the portions of coke formation on the surface of catalysts were reduced as the amounts of platinum doped increased.

  11. 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.

  12. 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.

  13. Magnetic and Cytotoxicity Properties of La1−x Sr x MnO3(0 ≤ x ≤ 0.5 Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

    Directory of Open Access Journals (Sweden)

    Siri Sineenat

    2009-01-01

    Full Text Available Abstract This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La1−x Sr x MnO3(LSMO withx = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO3(LMO and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples ofx ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (M S and coercive field (H C were evaluated by vibrating sample magnetometry at room temperature (20 °C. The samples show paramagnetic behavior for all the samples withx = 0 or LMO, and a superparamagnetic behavior for the other samples havingM Svalues of ~20–47 emu/g and theH Cvalues of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.

  14. Deep ultra violet and visible Raman spectroscopy studies of ion implanted 6H-SiC: Recrytallisation behaviour and thermal decomposition/thermal etching of the near surface region

    Energy Technology Data Exchange (ETDEWEB)

    Kuhudzai, R.J., E-mail: rj.kuhudzai@tuks.co.za [Physics Department, University of Pretoria, Pretoria (South Africa); Malherbe, J.B.; Berg, N.G. van der; Hlatshwayo, T.T.; Odutemowo, O.; Prinsloo, L.C. [Physics Department, University of Pretoria, Pretoria (South Africa); Buys, A.V. [Laboratory for Microscopy and Microanalysis, University of Pretoria (South Africa); Erasmus, R. [School of Physics, University of the Witwatersrand, Johannesburg (South Africa); Wendler, E. [Institut Für Festköperphysik, Friedrich-Schiller-Universität Jena, Jena (Germany)

    2015-12-15

    The recystallisation behaviour and thermal decomposition of the near surface amorphised region of 6H-SiC have been investigated by Raman spectroscopy. 360 keV ions of iodine and silver were implanted at room temperature into wafers of 6H-SiC resulting in the amorphisation of the near surface region. Vacuum annealing of the samples was performed at 1200 °C for 5 h and then sequentially from 1200 to 1600 °C in steps of 100 °C for 30 h at each annealing temperature. Raman spectroscopy was performed using two laser wavelength excitation regimes, the 514 nm laser (visible region) and the 244 nm laser (deep ultraviolet region, DUV). Measurements in the visible region for samples annealed at 1200 °C for 5 h showed that the characteristic 6H-SiC peaks, namely, the Transverse Optical (TO) and Longitudinal Optical (LO) are similar to the virgin samples, albeit with lower intensity due to some retained defects upon recystallisation of the SiC surface region. The similarities between the virgin spectra and the annealed sample were due to the deep penetration of the 514 nm laser into 6H-SiC resulting in the signal from the bulk undamaged 6H-SiC contributing to the overall spectra. However, DUV laser excitation, which only probes the near surface region, shows that after annealing the peaks are broader and asymmetrical compared to the virgin samples. DUV Raman spectra of samples annealed at 1600 °C indicate that SiC has completely decomposed and the top surface layer is now covered by a carbon layer. However the deeper penetrating laser in the visible region showed that the extent of decomposition at 1600 °C was greater for the silver implanted samples than for the iodine implanted samples.

  15. 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.

  16. Characters with personality!

    NARCIS (Netherlands)

    Bosch, K. van den; Brandenburgh, A.; Muller, T.J.; Heuvelink, A.

    2012-01-01

    Serious games offer an opportunity for learning communication skills by practicing conversations with one or more virtual characters, provided that the character(s) behave in accordance with their assigned properties and strate-gies. This paper presents an approach for developing virtual characters

  17. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    TECS

    water, which is the weight loss in the temperature range. 200–600°C and content of CO2 released during the de- composition of carbonate phases. 3. Results and discussion. Table 1 gives composition of the sample, which was deter- mined by the standard analysis (Vogel 1951). The main undesirable impurities in the ...

  18. 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.

  19. Toward the Elucidation of the Competing Role of Evaporation and Thermal Decomposition in Ionic Liquids: A Multitechnique Study of the Vaporization Behavior of 1-Butyl-3-methylimidazolium Hexafluorophosphate under Effusion Conditions.

    Science.gov (United States)

    Volpe, V; Brunetti, B; Gigli, G; Lapi, A; Vecchio Ciprioti, S; Ciccioli, A

    2017-11-16

    The evaporation/decomposition behavior of the imidazolium ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF 6 ) was investigated in the overall temperature range 425-551 K by means of the molecular-effusion-based techniques Knudsen effusion mass loss (KEML) and Knudsen effusion mass spectrometry (KEMS), using effusion orifices of different size (from 0.2 to 3 mm in diameter). Specific effusion fluxes measured by KEML were found to depend markedly on the orifice size, suggesting the occurrence of a kinetically delayed evaporation/decomposition process. KEMS experiments revealed that other species are present in the vapor phase besides the intact ion pair BMImPF 6 (g) produced by the simple evaporation BMImPF 6 (l) = BMImPF 6 (g), with relative abundances depending on the orifice size-the larger the orifice, the larger the contribution of the BMImPF 6 (g) species. By combining KEML and KEMS results, the conclusion is drawn that in the investigated temperature range, when small effusion orifices are used, a significant part of the mass loss/volatility of BMImPF 6 is due to molecular products formed by decomposition/dissociation processes rather than to evaporated intact ion pairs. Additional experiments performed by nonisothermal thermogravimetry-differential thermal analysis (TG-DTA) further support the evidence of simultaneous evaporation/decomposition, although the conventional decomposition temperature derived from TG curves is much higher than the temperatures covered in effusion experiments. Partial pressures of the BMImPF 6 (g) species were derived from KEMS spectra and analyzed by second- and third-law methods giving a value of Δ evap H 298K ° = 145.3 ± 2.9 kJ·mol -1 for the standard evaporation enthalpy of BMImPF 6 . A comparison is done with the behavior of the 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide (BMImNTf 2 ) ionic liquid.

  20. Actor/Character Dualism

    DEFF Research Database (Denmark)

    Riis, Johannes

    2012-01-01

    Our perception of agency may be inherently fallible, and this may explain not only our general awareness of actors when engaged in fictional characters but also the specific case of paradoxical characters...

  1. Decomposition of metal nitrate solutions

    International Nuclear Information System (INIS)

    Haas, P.A.; Stines, W.B.

    1982-01-01

    Oxides in powder form are obtained from aqueous solutions of one or more heavy metal nitrates (e.g. U, Pu, Th, Ce) by thermal decomposition at 300 to 800 deg C in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal. (author)

  2. Modeling Decomposition of Unconfined Rigid Polyurethane Foam

    National Research Council Canada - National Science Library

    Hobbs, Michael

    1999-01-01

    The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer...

  3. Constructing Sheet-On-Sheet Structured Graphitic Carbon Nitride/Reduced Graphene Oxide/Layered MnO2 Ternary Nanocomposite with Outstanding Catalytic Properties on Thermal Decomposition of Ammonium Perchlorate

    Science.gov (United States)

    Xu, Jianhua; Li, Dongnan; Chen, Yu; Tan, Linghua; Kou, Bo; Wan, Fushun; Jiang, Wei; Li, Fengsheng

    2017-01-01

    We unprecedentedly report that layered MnO2 nanosheets were in situ formed onto the surface of covalently bonded graphitic carbon nitride/reduced graphene oxide nanocomposite (g-C3N4/rGO), forming sheet-on-sheet structured two dimension (2D) graphitic carbon nitride/reduced graphene oxide/layered MnO2 ternary nanocomposite (g-C3N4/rGO/MnO2) with outstanding catalytic properties on thermal decomposition of ammonium perchlorate (AP). The covalently bonded g-C3N4/rGO was firstly prepared by the calcination of graphene oxide-guanidine hydrochloride precursor (GO-GndCl), following by its dispersion into the KMnO4 aqueous solution to construct the g-C3N4/rGO/MnO2 ternary nanocomposite. FT-IR, XRD, Raman as well as the XPS results clearly demonstrated the chemical interaction between g-C3N4, rGO and MnO2. TEM and element mapping indicated that layered g-C3N4/rGO was covered with thin MnO2 nanosheets. Furthermore, the obtained g-C3N4/rGO/MnO2 nanocomposite exhibited promising catalytic capacity on thermal decomposition of AP. Upon addition of 2 wt % g-C3N4/rGO/MnO2 ternary nanocomposite as catalyst, the thermal decomposition temperature of AP was largely decreased up by 142.5 °C, which was higher than that of pure g-C3N4, g-C3N4/rGO and MnO2, respectively, demonstrating the synergistic catalysis of the as-prepared nanocomposite. PMID:29244721

  4. Constructing Sheet-On-Sheet Structured Graphitic Carbon Nitride/Reduced Graphene Oxide/Layered MnO2 Ternary Nanocomposite with Outstanding Catalytic Properties on Thermal Decomposition of Ammonium Perchlorate

    Directory of Open Access Journals (Sweden)

    Jianhua Xu

    2017-12-01

    Full Text Available We unprecedentedly report that layered MnO2 nanosheets were in situ formed onto the surface of covalently bonded graphitic carbon nitride/reduced graphene oxide nanocomposite (g-C3N4/rGO, forming sheet-on-sheet structured two dimension (2D graphitic carbon nitride/reduced graphene oxide/layered MnO2 ternary nanocomposite (g-C3N4/rGO/MnO2 with outstanding catalytic properties on thermal decomposition of ammonium perchlorate (AP. The covalently bonded g-C3N4/rGO was firstly prepared by the calcination of graphene oxide-guanidine hydrochloride precursor (GO-GndCl, following by its dispersion into the KMnO4 aqueous solution to construct the g-C3N4/rGO/MnO2 ternary nanocomposite. FT-IR, XRD, Raman as well as the XPS results clearly demonstrated the chemical interaction between g-C3N4, rGO and MnO2. TEM and element mapping indicated that layered g-C3N4/rGO was covered with thin MnO2 nanosheets. Furthermore, the obtained g-C3N4/rGO/MnO2 nanocomposite exhibited promising catalytic capacity on thermal decomposition of AP. Upon addition of 2 wt % g-C3N4/rGO/MnO2 ternary nanocomposite as catalyst, the thermal decomposition temperature of AP was largely decreased up by 142.5 °C, which was higher than that of pure g-C3N4, g-C3N4/rGO and MnO2, respectively, demonstrating the synergistic catalysis of the as-prepared nanocomposite.

  5. 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.

  6. Constructing Sheet-On-Sheet Structured Graphitic Carbon Nitride/Reduced Graphene Oxide/Layered MnO₂ Ternary Nanocomposite with Outstanding Catalytic Properties on Thermal Decomposition of Ammonium Perchlorate.

    Science.gov (United States)

    Xu, Jianhua; Li, Dongnan; Chen, Yu; Tan, Linghua; Kou, Bo; Wan, Fushun; Jiang, Wei; Li, Fengsheng

    2017-12-15

    We unprecedentedly report that layered MnO₂ nanosheets were in situ formed onto the surface of covalently bonded graphitic carbon nitride/reduced graphene oxide nanocomposite (g-C₃N₄/rGO), forming sheet-on-sheet structured two dimension (2D) graphitic carbon nitride/reduced graphene oxide/layered MnO₂ ternary nanocomposite (g-C₃N₄/rGO/MnO₂) with outstanding catalytic properties on thermal decomposition of ammonium perchlorate (AP). The covalently bonded g-C₃N₄/rGO was firstly prepared by the calcination of graphene oxide-guanidine hydrochloride precursor (GO-GndCl), following by its dispersion into the KMnO₄ aqueous solution to construct the g-C₃N₄/rGO/MnO₂ ternary nanocomposite. FT-IR, XRD, Raman as well as the XPS results clearly demonstrated the chemical interaction between g-C₃N₄, rGO and MnO₂. TEM and element mapping indicated that layered g-C₃N₄/rGO was covered with thin MnO₂ nanosheets. Furthermore, the obtained g-C₃N₄/rGO/MnO₂ nanocomposite exhibited promising catalytic capacity on thermal decomposition of AP. Upon addition of 2 wt % g-C₃N₄/rGO/MnO₂ ternary nanocomposite as catalyst, the thermal decomposition temperature of AP was largely decreased up by 142.5 °C, which was higher than that of pure g-C₃N₄, g-C₃N₄/rGO and MnO₂, respectively, demonstrating the synergistic catalysis of the as-prepared nanocomposite.

  7. 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.

  8. 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.

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

    International Nuclear Information System (INIS)

    Eloussifi, H.; Farjas, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.; Dammak, M.

    2013-01-01

    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 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

  10. 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....... During the decomposition of Ln2O2CO3 into the respective sesquioxides (Ln2O3), an intermediate plateau extending from approximately 550 to 850 °C appears in the TG traces. The overall composition during this stage corresponds approximately to Ln2O2.8(CO3)0.2, but the state is more probably a mixture...

  11. Preliminary Results Regarding the Present Morphometric Characters of Thermal Rudd, Scardinius racovitzai Müller 1958 from Pețea Spring Natural Reserve

    Directory of Open Access Journals (Sweden)

    Grigoraş Gabriela

    2015-12-01

    Full Text Available The precarious temperature regime, associated with the negative influence of other environmental and biotic factors, represents a major risk for the survival of the thermal rudd from the lake Ochiul Mare, located in the Pârâul Peţea natural reserve. Therefore, a complex morphometric and body geometry analysis was conducted on specimens collected in 2013 in order to define the variability of the present population. The relatively small sample size is due to legislative restrictions on collecting endangered species, so statistical methods of analysis were applied to increase confidence in the assertions.

  12. 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.

  13. Superior Thermostability, Good Detonation Properties, Insensitivity, and the Effect on the Thermal Decomposition of Ammonium Perchlorate for a New Solvent-Free 3D Energetic PbII-MOF.

    Science.gov (United States)

    Yang, Qi; Yang, Guoli; Zhang, Wendou; Zhang, Sheng; Yang, Zhaohui; Xie, Gang; Wei, Qing; Chen, Sanping; Gao, Shengli

    2017-07-06

    A new solvent-free energetic MOF, [Pb(HBTI)] n (1) (H 3 BTI=4,5-bis(1H-tetrazole)-1H-imidazole), has been synthesized under hydrothermal and acidic conditions. It was characterized by elemental analysis, IR, thermogravimetric, differential scanning calorimetry (DSC) and SEM. Single crystal X-ray diffraction analysis revealed that 1 features a rigid 3D framework architecture free of solvent molecules. Thermal analysis demonstrated that the thermostability of 1 was up to 325 °C. Non-isothermal kinetic and apparent thermodynamic parameters of exothermic decomposition process of 1 were determined by Kissinger's and Ozawa's methods. Through oxygen-bomb combustion calorimetry, the standard molar enthalpy of formation of 1 was determined. The calculated detonation properties (heat of detonation, detonation velocity and detonation pressure) and sensitivity tests of 1 were carried out. In addition, 1 was explored as combustion promoter to accelerate the thermal decompositions of ammonium perchlorate (AP) by differential scanning calorimetry. Experimental results indicated that 1 possesses potential application prospects in the field of explosives and propellants. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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.

  15. Social character of materialism.

    Science.gov (United States)

    Chatterjee, A; Hunt, J M; Kernan, J B

    2000-06-01

    Scores for 170 undergraduates on Richins and Dawson's Materialism scale were correlated with scores on Kassarjian's Social Preference Scale, designed to measure individuals' character structure. A correlation of .26 between materialism and other-directed social character suggested that an externally oriented reference system guides materialists' perceptions, judgments, acquisitions, and possessions.

  16. Critical analysis of nitramine decomposition data: Activation energies and frequency factors for HMX and RDX decomposition

    Science.gov (United States)

    Schroeder, M. A.

    1980-01-01

    A summary of a literature review on thermal decomposition of HMX and RDX is presented. The decomposition apparently fits first order kinetics. Recommended values for Arrhenius parameters for HMX and RDX decomposition in the gaseous and liquid phases and for decomposition of RDX in solution in TNT are given. The apparent importance of autocatalysis is pointed out, as are some possible complications that may be encountered in interpreting extending or extrapolating kinetic data for these compounds from measurements carried out below their melting points to the higher temperatures and pressure characteristic of combustion.

  17. Influence of Tree Characters and Climate on Litter Characteristics in ...

    African Journals Online (AJOL)

    Litter production and decomposition rates have great importance in maintaining the fertility of the soil. The study was carried out to determine the relationship tree characters (girth size, canopy radius, tree height, leaf area and number of primary branches), litter production and quality, and climatic variables among stands of ...

  18. 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.

  19. Madness in Shakespeare's Characters

    Directory of Open Access Journals (Sweden)

    Nuno Borja-Santos

    2014-10-01

    Full Text Available This paper begins with an introduction where the aims are explained: a psychopathological analysis of a Shakespearean character - Othello – followed by the discussion of the English dramatist’s importance in helping us understand madness in the emergent world of Renaissance. The main characteristics of Othello’s personality, which allowed the development of his jealousy delusion, are described. Finally, the conclusions underline the overlap of the symptoms developed by the character with the DSM-IV classification.

  20. Magnéli phases Ti{sub 4}O{sub 7} and Ti{sub 8}O{sub 15} and their carbon nanocomposites via the thermal decomposition-precursor route

    Energy Technology Data Exchange (ETDEWEB)

    Conze, S., E-mail: susan.conze@ikts.fraunhofer.de [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany); Veremchuk, I. [Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden (Germany); Reibold, M. [Technical University of Dresden, Zum Triebenberg 50, 01328 Dresden (Zaschendorf) (Germany); Matthey, B.; Michaelis, A. [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany); Grin, Yu. [Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden (Germany); Kinski, I. [Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstr. 28, 01277 Dresden (Germany)

    2015-09-15

    A new synthetic approach for producing nano-powders of the Magnéli phases Ti{sub 4}O{sub 7}, Ti{sub 8}O{sub 15} and their carbon nanocomposites by thermal decomposition-precursor route is proposed. The formation mechanism of the single-phase carbon nanocomposites (Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C) from metal–organic precursors is studied using FT-IR, elemental analysis, TG, STA-MS and others. The synthesis parameters and conditions were optimized to prepare the target oxides with the desired microstructure and physical properties. The electrical and transport properties of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. These nano-materials are n-type semiconductors with relatively low thermal conductivity in contrast to the bulk species. The nanostructured carbon nanocomposites of Magnéli phases achieve a low thermal conductivity close to 1 W/m K at RT. The maximum ZT{sub 570} {sub °C} values are 0.04 for Ti{sub 4}O{sub 7}/C powder nanocomposite and 0.01 for Ti{sub 8}O{sub 15}/C bulk nanocomposite. - Graphical abstract: From the precursor to the produced titanium oxide pellet and its microstructure (SEM, TEM micrographs) as well as results of phase and thermoelectric analyses. - Highlights: • Magnéli phases Ti{sub 4}O{sub 7}/Ti{sub 8}O{sub 15} via thermal decomposition-precursor route is proposed. • The formation mechanism of the nanocomposites Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. • Microstructure of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are examined. • The electrical and transport properties of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. • The maximum figure of mertit ZT{sub 570} {sub °C} of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are 0.01 and 0.04.

  1. The Varieties of Character and Some Implications for Character Education.

    Science.gov (United States)

    Baehr, Jason

    2017-06-01

    The moral and civic dimensions of personal character have been widely recognized and explored. Recent work by philosophers, psychologists, and education theorists has drawn attention to two additional dimensions of character: intellectual character and "performance" character. This article sketches a "four-dimensional" conceptual model of personal character and some of the character strengths or "virtues" proper to each dimension. In addition to exploring how the dimensions of character are related to each other, the article also examines the implications of this account for character education undertaken in a youth or adolescent context. It is argued that "intellectual character education," which emphasizes the development of intellectual virtues like curiosity, open-mindedness, and intellectual courage, is an underexplored but especially promising approach in this context. The relationship between intellectual character education and traditional character education, which emphasizes the development of moral and civic virtues like kindness, generosity, and tolerance, is also explored.

  2. Knowing Chinese character grammar.

    Science.gov (United States)

    Myers, James

    2016-02-01

    Chinese character structure has often been described as representing a kind of grammar, but the notion of character grammar has hardly been explored. Patterns in character element reduplication are particularly grammar-like, displaying discrete combinatoriality, binarity, phonology-like final prominence, and potentially the need for symbolic rules (X→XX). To test knowledge of these patterns, Chinese readers were asked to judge the acceptability of fake characters varying both in grammaticality (obeying or violating reduplication constraints) and in lexicality (of the reduplicative configurations). While lexical knowledge was important (lexicality improved acceptability and grammatical configurations were accepted more quickly when also lexical), grammatical knowledge was important as well, with grammaticality improving acceptability equally for lexical and nonlexical configurations. Acceptability was also higher for more frequent reduplicative elements, suggesting that the reduplicative configurations were decomposed. Chinese characters present an as-yet untapped resource for exploring fundamental questions about the nature of the human capacity for grammar. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. 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

  4. Character development in adolescents.

    Science.gov (United States)

    Kessler, G R; Ibrahim, F A; Kahn, H

    1986-01-01

    This study explored the effects of a program consisting of communication and counseling skills, assertiveness training and moral dilemmas on the character development, i.e., moral reasoning, ego development, and assertiveness of high school students. It was hypothesized that exposure to the experimental treatment would enhance the character development of high school students. Fifty-four high school seniors enrolled in three psychology classes were assigned randomly to two treatment groups and one control group. Assessment instruments were the Defining Issues Test, to measure moral reasoning, the Washington University Sentence Completion Test, to measure ego development, and the Rathus Assertiveness Schedule, to measure assertiveness. A repeated measures analysis of variance was used to determine significant differences between control and treatment posttest means with respect to the dependent variables--moral reasoning, ego development, and assertiveness. The results demonstrated that the character development of the students in the experimental treatment group was affected significantly over time by the program.

  5. 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.

  6. Characterization of Cobalt Oxide Nanoparticles Prepared by the Thermal Decomposition of [Co(NH3)5(H2O)](NO3)3 Complex and Study of Their Photocatalytic Activity.

    Science.gov (United States)

    Farhadi, Saeed; Javanmard, Masoumeh; Nadri, Gholamali

    2016-01-01

    In this work, thermal decomposition of the [Co(NH3)5(H2O)](NO3)3 precursor complex was investigated under solid state conditions. Thermal analysis (TG/DTA) showed that the complexwas easily decomposed into the Co3O4 nanoparticles at low temperature (175 °C) without using any expensive and toxic solvent or a complicated equipment. The obtained product was identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Optical and magnetic properties of the products were studied by UV-visible spectroscopy and a vibrating sample magnetometer (VSM), respectively. FT-IR, XRD and EDX analyses confirmed the formation of highly pure spinel-type Co3O4 phase with cubic structure. SEM and TEM images showed that the Co3O4 nanoparticles have a sphere-like morphology with an average size of 17.5 nm. The optical absorption spectrum of the Co3O4 nanoparticles showed two band gaps of 2.20 and 3.45 eV, which in turn confirmed the semiconducting properties. The magnetic measurement showed a weak ferromagnetic order at room temperature. Photocatalytic degradation of methylene blue (MB) demonstrated that the as-prepared Co3O4 nanoparticles have good photocatalytic activity under visible-light irradiation.

  7. Thermal decomposition of [Co(en)3][Fe(CN)6]? 2H2O: Topotactic dehydration process, valence and spin exchange mechanism elucidation

    OpenAIRE

    Tr?vn??ek, Zden?k; Zbo?il, Radek; Matikov?-Ma?arov?, Miroslava; Draho?, Bohuslav; ?ern?k, Juraj

    2013-01-01

    Background The Prussian blue analogues represent well-known and extensively studied group of coordination species which has many remarkable applications due to their ion-exchange, electron transfer or magnetic properties. Among them, Co-Fe Prussian blue analogues have been extensively studied due to the photoinduced magnetization. Surprisingly, their suitability as precursors for solid-state synthesis of magnetic nanoparticles is almost unexplored. In this paper, the mechanism of thermal deco...

  8. Optical Character Recognition.

    Science.gov (United States)

    Converso, L.; Hocek, S.

    1990-01-01

    This paper describes computer-based optical character recognition (OCR) systems, focusing on their components (the computer, the scanner, the OCR, and the output device); how the systems work; and features to consider in selecting a system. A list of 26 questions to ask to evaluate systems for potential purchase is included. (JDD)

  9. Character Development Is Nonnegotiable.

    Science.gov (United States)

    Thibeau, Matthew J.

    1999-01-01

    Contends that Catholic educators have a proven and lasting program to guide character building in their students. States that the basis for this important moral development is teaching good habits, and that the values presented in the Gospel are integrated into all curriculum areas, providing opportunities for students and faculty to reflect,…

  10. of some generic characters

    African Journals Online (AJOL)

    1986-06-12

    Jun 12, 1986 ... The new species is closest to Homopholis fascists of East Africa and Ethiopia Some generic characters are discussed. 'n Nuwe geitjie-spesie, Homopholis mulleri, van Noord-Transvaal (Suid-Afrika), word beskryf. Dit word met die ander twee spesies van die genus in Afrika vergelyk. Die nuwe spesie is ...

  11. Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    S. K. Deb Nath

    2014-01-01

    Full Text Available Perfluoropolyethers (PFPEs are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenonaffects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multidented functional lubricants such as ARJ-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.

  12. 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

  13. 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.

  14. A Two-Step Method to Synthesize BaSn(OH6 Crystalline Nanorods and Their Thermal Decomposition to Barium Stannate

    Directory of Open Access Journals (Sweden)

    Xiaohong Wu

    2012-01-01

    Full Text Available A novel two-step technique is introduced to synthesize BaSn(OH6 nanorods. The method involves the preparation of precursor Na2Sn(OH6 crystals in aqueous solution via hydrothermal method and the ion-exchange reaction between Na2Sn(OH6 crystals and Ba2+ solution that followed, assisted by ultrasonic treatment. The BaSn(OH6 nanorods array are formed due to the split of plate-formed Na2Sn(OH6 during the ion-exchange treatment. The influence of the surfactant on the growth of the one-dimensional (1D BaSn(OH6 nanostructures is investigated. In addition, the powder BaSnO3 has been obtained by thermal treatment at 450°C for 5 h under inert gas protecting condition using BaSn(OH6 nanorods as precursor. The 1D shape of BaSn(OH6 was retained after thermal treatment.

  15. Kinetic modeling of the polymer-derived ceramics route: investigation of the thermal decomposition kinetics of poly[B-(methylamino)borazine] precursors into boron nitride.

    Science.gov (United States)

    Bernard, Samuel; Fiaty, Koffi; Cornu, David; Miele, Philippe; Laurent, Pierre

    2006-05-11

    A complete kinetic modeling of the polymer-derived ceramics (PDCs) route is achieved for the first time through the investigation of the solid-state decomposition of a typical melt-spinnable poly[B-(methylamino)borazine] into boron nitride fibers at various heating rates. Through the use of the Lorentz fitting approach, it is shown that the two-step weight loss associated with the polymer-to-ceramic conversion is governed by a complex interplay of five diffusion-type transport mechanisms that are independent of the applied heating schedule. The application of the Friedman method to dynamic thermogravimetry data yields Ea and ln A values that are seen to increase with the extent of the ceramic conversion from region one (Ea = 38.73 kJ mol(-1)) to region five (Ea = 146.64 kJ mol(-1)). This fact indicates that both the mechanisms within those regions are parallel routes to the formation of the final solid-state material and their complexity increases with the conversion progress. The cross-linking process (first weight loss) of the polymer is governed by three dependent poorly energetic mechanisms. The first weight loss is activated by ammonolysis reactions that provide a modified polymer capable of undergoing condensation reactions in regions two and three to yield a highly cross-linked polymer. A large evolution of methylamine is identified during this process. Mineralization (region four) and ceramization (region five) steps are represented by two highly energetic multistep mechanisms. The mineralization step is associated with a large evolution of methylamine and occurs during the transition between the cross-linking and ceramization processes through the cleavage of the inter-ring B-N bonds. Ceramization represents the end of the polymer-to-ceramic conversion in which the planar consolidation of BN hexagons occurs through complex structural rearrangements of the borazine units (cleavage of the intraring B-N bonds) accompanied with an ammonia evolution. Finally

  16. Thermal decomposition of vinyl- and allylsilane platinum(II complexes and platinum(II catalysed synthesis of (E,(E-1,4-diphenyl-1,3-butadiene

    Directory of Open Access Journals (Sweden)

    Paul P. Mebe

    2008-12-01

    Full Text Available Thermal stabilities of Pt(II complexes: K[PtCl3(CH2=CHSiMe3], K[PtCl3(CH2=CHCH2SiMe3], K[(acacPtCl(CH2=CHSiMe3] and [PtCl(CH2=CHCH2SiMe3]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex decomposed above about 125 oE,(E-1,4-diphenyl-1,3-butadiene was stereoselectively synthesised in good yield from (E-β-styrylsilane in the presence of Zeise’s salt.

  17. 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...

  18. Kinetics and equilibrium studies on the treatment of nitric acid with Mg-Al oxide obtained by thermal decomposition of NO3(-)-intercalated Mg-Al layered double hydroxide.

    Science.gov (United States)

    Kameda, Tomohito; Fubasami, Yuki; Yoshioka, Toshiaki

    2011-10-15

    Mg-Al oxide obtained by thermal decomposition of NO(3)(-)-intercalated Mg-Al layered double hydroxide (NO(3)·Mg-Al LDH) was found to treat HNO(3), acting as both a neutralizer and fixative for NO(3)(-). The degree of NO(3)(-) removal increased with time, Mg-Al oxide quantity, and temperature. The NO(3)(-) removal could be represented by a first-order reaction. The apparent activation energy was 52.9 kJ mol(-1), confirming that NO(3)(-) removal by Mg-Al oxide proceeded under chemical reaction control. Furthermore, the adsorption of NO(3)(-) on Mg-Al oxide could be expressed by a Langmuir-type adsorption isotherm. The maximum adsorption amount and equilibrium adsorption constant were 3.8 mmol g(-1) and 1.33, respectively. The Gibbs free energy change was -18 kJ mol(-1), confirming that the uptake of NO(3)(-) from HNO(3) by Mg-Al oxide proceeded spontaneously. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. 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.

  20. Structural refinement of Nd[Fe(CN)6].4H2O and study of NdFeO3 obtained by its oxidative thermal decomposition at very low temperatures

    International Nuclear Information System (INIS)

    Navarro, M. Carolina; Pannunzio-Miner, Elisa V.; Pagola, Silvina; Gomez, M. Ines; Carbonio, Raul E.

    2005-01-01

    The crystal structure of Nd[Fe(CN) 6 ].4H 2 O has been refined by Rietveld analysis using high resolution synchrotron powder X-ray diffraction data. It belonged to the orthorhombic crystal system, Cmcm space group, with cell parameters: a=7.473952(1)A, b=12.919104(2)A and c=13.800549(2)A. The change in space group from P6 3 /m which is observed in the pentahydrates (LnFe(CN) 6 .5H 2 O) to Cmcm in the tetrahydrates has been analyzed to be a consequence of the change in 9-fold coordination of Nd 3+ in the pentahydrates to 8-fold coordination in the tetrahydrates, which changes the Nd 3+ environment from tricapped trigonal prism to a distorted tricapped trigonal prism or square antiprism. Its decomposition process in air to produce NdFeO 3 has been followed by thermogravimetric and differential thermal analysis, IR spectroscopy and laboratory powder XRD. We found that it is possible to synthesize crystalline NdFeO 3 at temperatures as low as 380 o C and refine the structure of single phase crystalline NdFeO 3 synthesized by this method at 600 deg. C

  1. Thermogravimetry coupled to single photon ionization quadrupole mass spectrometry: a tool to investigate the chemical signature of thermal decomposition of polymeric materials.

    Science.gov (United States)

    Saraji-Bozorgzad, M; Geissler, R; Streibel, T; Mühlberger, F; Sklorz, M; Kaisersberger, E; Denner, T; Zimmermann, R

    2008-05-01

    Mass spectrometry (MS) is an established analytical technique to analyze evolved gas in thermogravimetry (TG). In this study, for the first time a novel SPI-MS technique using an electron beam pumped VUV excimer lamp as photon source (lambda = 126 nm) was employed in conjunction with thermogravimetry. The coupling was achieved with an improved heated interface and adjacent transfer capillary between TG and ion source of a quadrupole mass spectrometer. The feasibility of this approach was proven by investigating semivolatile substances such as long-chain alkanes (heptadecane C17H36), polymers, e.g., polystyrene, polycarbonate, and acrylonitrile-butadiene-styrene, polymer mixtures and blends. Mass spectra with almost no fragmentation were obtained, and quantification of selected substances could be achieved. Polymer mixtures could be distinguished by their SPI mass spectra, and the effect of premixing of polymers has been accessed. Its unique attributes render the TA-SPI-MS method a promising new tool for quantitative and qualitative evaluation of complex organic thermal degradation products.

  2. Photocatalytic decomposition of selected estrogens and their estrogenic activity by UV-LED irradiated TiO2 immobilized on porous titanium sheets via thermal-chemical oxidation

    International Nuclear Information System (INIS)

    Arlos, Maricor J.; Liang, Robert; Hatat-Fraile, Melisa M.; Bragg, Leslie M.; Zhou, Norman Y.; Servos, Mark R.; Andrews, Susan A.

    2016-01-01

    Highlights: • TiO 2 self-assembled on oxidized porous titanium sheets. • UV-LED/TiO 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 2 ) has potential applications for the removal of EDCs from water. TiO 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 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.

  3. Decomposition of Sodium Tetraphenylborate

    International Nuclear Information System (INIS)

    Barnes, M.J.

    1998-01-01

    The chemical decomposition of aqueous alkaline solutions of sodium tetraphenylborate (NaTPB) has been investigated. The focus of the investigation is on the determination of additives and/or variables which influence NaTBP decomposition. This document describes work aimed at providing better understanding into the relationship of copper (II), solution temperature, and solution pH to NaTPB stability

  4. Probability matrix decomposition models

    NARCIS (Netherlands)

    Maris, E.; DeBoeck, P.; Mechelen, I. van

    1996-01-01

    In this paper, we consider a class of models for two-way matrices with binary entries of 0 and 1. First, we consider Boolean matrix decomposition, conceptualize it as a latent response model (LRM) and, by making use of this conceptualization, generalize it to a larger class of matrix decomposition

  5. The typeface character

    DEFF Research Database (Denmark)

    Beier, Sofie

    2015-01-01

    Research from the fields of neuroscience and psychology, shows that typefaces can carry different semantic associations. However, to be able to read a text, the reader can no longer focus on the character of the typeface, as the human mind is incapable of simultaneously giving full attention...... to different matters. This results in the inherent conflict of typefaces that they on one hand need to draw attention to themselves, and on the other hand need to let go of this attention for the content to be read....

  6. Character Education: A Critical Analysis

    Science.gov (United States)

    Edmonson, Stacey; Tatman, Robert; Slate, John R.

    2009-01-01

    In this article, we examined the history behind character education because we believe that character education an integral component of the educational enterprise. Major contributors to the importance of character education in the 18th, 19th, and 20th centuries were discussed. Then we focused on the highlights of the last five decades of the 20th…

  7. Character Education: An Historical Overview

    Science.gov (United States)

    Edmonson, Stacey; Tatman, Robert; Slate, John R.

    2009-01-01

    Character education is integral to the educational enterprise. Recent character education endeavors across the educational landscape have originated from a variety of different organizational sources. This article provides a review of the progress character education from the 18th century up through the 21st.

  8. Bring Character Education into Classroom

    Science.gov (United States)

    Agboola, Alex; Tsai, Kaun Chen

    2012-01-01

    Character education is a growing discipline with the deliberate attempt to optimize students' ethical behavior. The outcome of character education has always been encouraging, solidly, and continually preparing the leaders of tomorrow. The promotion of character education should not just a leap service but has an action plan for practice. In order…

  9. 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...

  10. Radiation decomposition of chlorates

    International Nuclear Information System (INIS)

    Patil, S.F.; Patil, B.T.

    1980-01-01

    Radiation induced decomposition yields of chloride, hypochlorite and chlorite have been determined in chlorates of barium, calcium and strontium for different γ doses. The G-values of the products in anhydrous barium and calcium chlorates are found to be greater than in the corresponding hydrated forms showing that the water of crystallization plays a quenching role in the radiation decomposition of chlorates. The results are explained on the assumption that the excitation energy of the fraction of the metal ions is transferred to the water molecules in the crystal lattice resulting in the excitation or decomposition of the water molecules rather than chlorate ions. (orig.) [de

  11. 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

  12. Isothermal Decomposition of Hydrogen Peroxide Dihydrate

    Science.gov (United States)

    Loeffler, M. J.; Baragiola, R. A.

    2011-01-01

    We present a new method of growing pure solid hydrogen peroxide in an ultra high vacuum environment and apply it to determine thermal stability of the dihydrate compound that forms when water and hydrogen peroxide are mixed at low temperatures. Using infrared spectroscopy and thermogravimetric analysis, we quantified the isothermal decomposition of the metastable dihydrate at 151.6 K. This decomposition occurs by fractional distillation through the preferential sublimation of water, which leads to the formation of pure hydrogen peroxide. The results imply that in an astronomical environment where condensed mixtures of H2O2 and H2O are shielded from radiolytic decomposition and warmed to temperatures where sublimation is significant, highly concentrated or even pure hydrogen peroxide may form.

  13. Photochemical decomposition of catecholamines

    International Nuclear Information System (INIS)

    Mol, N.J. de; Henegouwen, G.M.J.B. van; Gerritsma, K.W.

    1979-01-01

    During photochemical decomposition (lambda=254 nm) adrenaline, isoprenaline and noradrenaline in aqueous solution were converted to the corresponding aminochrome for 65, 56 and 35% respectively. In determining this conversion, photochemical instability of the aminochromes was taken into account. Irradiations were performed in such dilute solutions that the neglect of the inner filter effect is permissible. Furthermore, quantum yields for the decomposition of the aminochromes in aqueous solution are given. (Author)

  14. Maya Studio Projects Photorealistic Characters

    CERN Document Server

    Palamar, Todd

    2011-01-01

    Create realistic characters with Maya tools and this project-based book Maya character generation tools are extremely sophisticated, and there's no better way to learn all their capabilities than by working through the projects in this hands-on book. This official guide focuses on understanding and implementing Maya's powerful tools for creating realistic characters for film, games, and TV. Use a variety of tools to create characters from skeleton to clothing, including hairstyles and facial hair, and learn how to use Performance Capture. A DVD includes supplementary videos, project support fi

  15. Thermal decomposition of supported lithium nitrate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Maria Lucia [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Lick, Ileana Daniela [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina); Ponzi, Marta Isabel [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Castellon, Enrique Rodriguez; Jimenez-Lopez, Antonio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia. Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Ponzi, Esther Natalia, E-mail: eponzi@quimica.unlp.edu.ar [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina)

    2010-02-20

    New catalysts for soot combustion were prepared by impregnation of different supports (SiO{sub 2}, ZrO{sub 2} and ZrO{sub 2}.nH{sub 2}O) with a LiNO{sub 3} solution and then characterized by means of FTIR, XPS, TGA and UV-vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO{sub 3}/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li{sub 2}O/supports). Catalysts prepared using LiNO{sub 3} are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O{sub 2} mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an 'in situ' nitrate ion.

  16. THERMAL DECOMPOSITION OF VINYL- AND ALLYLSILANE ...

    African Journals Online (AJOL)

    a

    laboratory by a Grignard-type reaction from β-bromostyrene and chlorotrimethylsilane. 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 ...

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

    African Journals Online (AJOL)

    denise

    INTR. ODUCTION. Biomass in the form of household, municipal, industrial and agricultural wastes will continue to play an important role in the generation of energy, fuels and chemicals. Biomass is relatively abundant and renewable, and this makes it particularly attractive in relation to the non-renewable fossil fuels.

  18. 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.

  19. alumina phase transformation from thermal decomposition

    African Journals Online (AJOL)

    HOD

    Alumina is one of the major components used as catalyst support, which is especially important with regard to ... alumina, has been a major catalytic support in automotive and petroleum industries, as well as in adsorption ..... Catalyst in Steam Reforming of Dimethyl ether: Cu/γ-Al2O3/Al Catalyst Degradation Behaviors and.

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

    African Journals Online (AJOL)

    NJD

    which show interesting polymeric networks or chain struc- tures.1–3 They are used in many areas such as extraction and separation, germicides, catalysts, and functional materials. The nitrogen-containing ligand ..... appropriate amount of ethanol and the pH was adjusted to 6–7 by using 1.0 mol L–1 NaOH solution.

  1. Thermal Decomposition of Nitrated Tributyl Phosphate

    International Nuclear Information System (INIS)

    Paddleford, D.F.; Hou, Y.; Barefield, E.K.; Tedder, D.W.; Abdel-Khalik, S.I.

    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

  2. Infrared multiphoton absorption and decomposition

    International Nuclear Information System (INIS)

    Evans, D.K.; McAlpine, R.D.

    1984-01-01

    The discovery of infrared laser induced multiphoton absorption (IRMPA) and decomposition (IRMPD) by Isenor and Richardson in 1971 generated a great deal of interest in these phenomena. This interest was increased with the discovery by Ambartzumian, Letokhov, Ryadbov and Chekalin that isotopically selective IRMPD was possible. One of the first speculations about these phenomena was that it might be possible to excite a particular mode of a molecule with the intense infrared laser beam and cause decomposition or chemical reaction by channels which do not predominate thermally, thus providing new synthetic routes for complex chemicals. The potential applications to isotope separation and novel chemistry stimulated efforts to understand the underlying physics and chemistry of these processes. At ICOMP I, in 1977 and at ICOMP II in 1980, several authors reviewed the current understandings of IRMPA and IRMPD as well as the particular aspect of isotope separation. There continues to be a great deal of effort into understanding IRMPA and IRMPD and we will briefly review some aspects of these efforts with particular emphasis on progress since ICOMP II. 31 references

  3. Lexical processing of Chinese sub-character components: Semantic activation of phonetic radicals as revealed by the Stroop effect.

    Science.gov (United States)

    Yeh, Su-Ling; Chou, Wei-Lun; Ho, Pokuan

    2017-11-17

    Most Chinese characters are compounds consisting of a semantic radical indicating semantic category and a phonetic radical cuing the pronunciation of the character. Controversy surrounds whether radicals also go through the same lexical processing as characters and, critically, whether phonetic radicals involve semantic activation since they can also be characters when standing alone. Here we examined these issues using the Stroop task whereby participants responded to the ink color of the character. The key finding was that Stroop effects were found when the character itself had a meaning unrelated to color, but contained a color name phonetic radical (e.g., "guess", with the phonetic radical "cyan", on the right) or had a meaning associated with color (e.g., "pity", with the phonetic radical "blood" on the right which has a meaning related to "red"). Such Stroop effects from the phonetic radical within a character unrelated to color support that Chinese character recognition involves decomposition of characters into their constituent radicals; with each of their meanings including phonetic radicals activated independently, even though it would inevitably interfere with that of the whole character. Compared with the morphological decomposition in English whereby the semantics of the morphemes are not necessarily activated, the unavoidable semantic activation of phonetic radicals represents a unique feature in Chinese character processing.

  4. THE NEED FOR CHARACTER EDUCATION

    Directory of Open Access Journals (Sweden)

    Aynur Pala

    2011-07-01

    Full Text Available Character education is a national movement creatingschools that foster ethical,responsible and caring young people by modelling and teaching good characterthrough emphasis on universal values that we all share. It is the intentional,proactive effort by schools, districts and states to instil in their students importantcore ethical values such as caring, honesty, fairness, responsibility and respect forself and others.Good character is not formed automatically; it is developed over time through asustained process of teaching, example, learning and practice. It is developedthrough character education. The intentional teaching of good character isparticularly important in today’s society since ouryouth face many opportunitiesand dangers unknown to earlier generations. They are bombarded with many morenegative influences through the media and other external sources prevalent intoday’s culture. Since children spend about 900 hours a year in school, it isessential that schools resume a proactive role in assisting families andcommunities by developing caring, respectful environments where students learncore, ethical values. When a comprehensive approachto character education isused, a positive moral culture is created in the school—a total school environmentthat supports the values taught in the classroom (Character Education Partnership,2010.The aim of this study is to provide guidelines forthe elements need for effectiveand comprehensive character education. And to emphasize the need of charactereducation to help students develop good character, which includes knowing,caring about and acting upon core ethical values such as respect, responsibility,honesty, fairness and compassion.

  5. First Steps in Character Education

    Science.gov (United States)

    Hill, Patty Smith

    2017-01-01

    For many centuries, there has been theoretical statements asserting faith in character as the main objective in education, but it is only comparatively recently enough has been known about character and the scientific conditions for its development to make an honored place for it in the curricula. Today, it is creeping into curricula under new…

  6. Kinetic study of lithium-cadmium ternary amalgam decomposition

    International Nuclear Information System (INIS)

    Cordova, M.H.; Andrade, C.E.

    1992-01-01

    The effect of metals, which form stable lithium phase in binary alloys, on the formation of intermetallic species in ternary amalgams and their effect on thermal decomposition in contact with water is analyzed. Cd is selected as ternary metal, based on general experimental selection criteria. Cd (Hg) binary amalgams are prepared by direct contact Cd-Hg, whereas Li is formed by electrolysis of Li OH aq using a liquid Cd (Hg) cathodic well. The decomposition kinetic of Li C(Hg) in contact with 0.6 M Li OH is studied in function of ageing and temperature, and these results are compared with the binary amalgam Li (Hg) decomposition. The decomposition rate is constant during one hour for binary and ternary systems. Ageing does not affect the binary systems but increases the decomposition activation energy of ternary systems. A reaction mechanism that considers an intermetallic specie participating in the activated complex is proposed and a kinetic law is suggested. (author)

  7. Size-dependent decomposition temperature of nanoparticles: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shanshan; Cui, Zixiang; Xia, Xiaoyan; Xue, Yongqiang, E-mail: xyqlw@126.com

    2014-12-01

    Thermal decomposition of nanomaterials is often involved in the preparation and applications of nanomaterials, of which decomposition temperature can be surprisingly different from corresponding bulk materials. However, there is a lack of theoretical and experimental investigation on the relationship between the decomposition temperature and nanoparticle size. In present study, the relation between the decomposition temperature and the size of nanoparticles was derived theoretically, which indicates that the decomposition temperature decreases with the size of the nanoparticles decreasing, and there is a linear relationship between the decomposition temperature and the reciprocal of the particle size when the radius is bigger than 10 nm. Thermal decomposition experiments of nano-calcium carbonate with different sizes were carried out by thermo-gravimetric (TG), the onset decomposition temperatures (T{sub onset}) and the temperature of the DTG peaks (T{sub max}) were measured and both of them present well liner relationship with the reciprocal of the particle size. The depress regularity of the onset decomposition temperature of nano-calcium carbonate agrees with the derived thermodynamic relationship. This thermodynamic theory provides a quantitative description for the decomposition temperature of nanoparticles, also it can be used to predict and explain the thermal decomposition behavior of nanomaterials.

  8. 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.

  9. Solid-state thermal decomposition of the [Co(NH3)5CO3]NO3·0.5H2O complex: A simple, rapid and low-temperature synthetic route to Co3O4 nanoparticles

    International Nuclear Information System (INIS)

    Farhadi, Saeid; Safabakhsh, Jalil

    2012-01-01

    Highlights: ► [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O complex was used for preparing pure Co 3 O 4 nanoparticles. ► Co 3 O 4 nanoparticles were prepared at low temperature of 175 °C. ► Co 3 O 4 nanoparticles show a weak ferromagnetic behaviour at room temperature. ► The method is simple, low-cost and suitable for the production of Co 3 O 4 . - Abstract: Co 3 O 4 nanoparticles were easily prepared via the decomposition of the pentammine(carbonato)cobalt(III) nitrate precursor complex [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O at low temperature (175 °C). The product was characterized by thermal analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Brunauer–Emmett–Teller (BET) specific surface area measurements and magnetic measurements. The FT-IR, XRD, Raman and EDX results indicated that the synthesized Co 3 O 4 nanoparticles are highly pure and have a single phase. The TEM analysis revealed nearly uniform and quasi-spherical Co 3 O 4 nanoparticles with an average particle size of approximately 10 nm. The optical absorption spectrum of the Co 3 O 4 nanoparticles showed two direct band gaps of 2.18 and 3.52 eV with a red shift in comparison with previous reported values. The prepared Co 3 O 4 nanoparticles showed a weak ferromagnetic behaviour that could be attributed to uncompensated surface spins and/or finite-size effects. Using the present method, Co 3 O 4 nanoparticles can be produced without expensive organic solvents and complicated equipment. This simple, rapid, safe and low-cost synthetic route can be extended to the synthesis of other transition-metal oxides.

  10. 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...... of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation...... of the decomposition of any tensor of sub-generic rank, as opposed to widely used iterative algorithms with unproved global convergence (e.g. Alternate Least Squares or gradient descents). Second, it gives tools for understanding uniqueness conditions and for detecting the rank....

  11. Effect of pattern complexity on the visual span for Chinese and alphabet characters.

    Science.gov (United States)

    Wang, Hui; He, Xuanzi; Legge, Gordon E

    2014-07-03

    The visual span for reading is the number of letters that can be recognized without moving the eyes and is hypothesized to impose a sensory limitation on reading speed. Factors affecting the size of the visual span have been studied using alphabet letters. There may be common constraints applying to recognition of other scripts. The aim of this study was to extend the concept of the visual span to Chinese characters and to examine the effect of the greater complexity of these characters. We measured visual spans for Chinese characters and alphabet letters in the central vision of bilingual subjects. Perimetric complexity was used as a metric to quantify the pattern complexity of binary character images. The visual span tests were conducted with four sets of stimuli differing in complexity--lowercase alphabet letters and three groups of Chinese characters. We found that the size of visual spans decreased with increasing complexity, ranging from 10.5 characters for alphabet letters to 4.5 characters for the most complex Chinese characters studied. A decomposition analysis revealed that crowding was the dominant factor limiting the size of the visual span, and the amount of crowding increased with complexity. Errors in the spatial arrangement of characters (mislocations) had a secondary effect. We conclude that pattern complexity has a major effect on the size of the visual span, mediated in large part by crowding. Measuring the visual span for Chinese characters is likely to have high relevance to understanding visual constraints on Chinese reading performance. © 2014 ARVO.

  12. Character profiles and life satisfaction.

    Science.gov (United States)

    Park, Hwanjin; Suh, Byung Seong; Kim, Won Sool; Lee, Hye-Kyung; Park, Seon-Cheol; Lee, Kounseok

    2015-04-01

    There is a surge of interest in subjective well-being (SWB), which concerns how individuals feel about their happiness. Life satisfaction tends to be influenced by individual psychological traits and external social factors. The aim of this study was to examine the relationship between individual character and SWB. Data from 3522 university students were analyzed in this study. Character profiles were evaluated using the Temperament and Character Inventory-Revised Short version (TCI-RS). Life satisfaction was assessed using the Satisfaction with Life Scale (SWLS). All statistical tests regarding the correlations between each character profile and life satisfaction were conducted using ANOVAs, t-tests, multiple linear regression models and correlation analyses. The creative (SCT) profile was associated with the highest levels of life satisfaction, whereas the depressive (sct) profile was associated with the lowest levels of life satisfaction. Additionally, high self-directedness, self-transcendence and cooperation were associated with high life satisfaction. The results of gender-adjusted multiple regression analysis showed that the effects of self-directedness were the strongest in the assessment of one's quality of life, followed by self-transcendence and cooperativeness, in that order. All of the three-character profiles were significantly correlated with one's quality of life, and the character profiles of TCI-RS explained 27.6% of life satisfaction in total. Among the three-character profiles, the self-directedness profile was most associated with life satisfaction. Our study was cross-sectional, and self-reported data from students at a single university were analyzed. The results of this study showed that, among the character profiles, the effects of self-directedness were the strongest for predicting life satisfaction. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Moral character in the workplace.

    Science.gov (United States)

    Cohen, Taya R; Panter, A T; Turan, Nazli; Morse, Lily; Kim, Yeonjeong

    2014-11-01

    Using two 3-month diary studies and a large cross-sectional survey, we identified distinguishing features of adults with low versus high levels of moral character. Adults with high levels of moral character tend to: consider the needs and interests of others and how their actions affect other people (e.g., they have high levels of Honesty-Humility, empathic concern, guilt proneness); regulate their behavior effectively, specifically with reference to behaviors that have positive short-term consequences but negative long-term consequences (e.g., they have high levels of Conscientiousness, self-control, consideration of future consequences); and value being moral (e.g., they have high levels of moral identity-internalization). Cognitive moral development, Emotionality, and social value orientation were found to be relatively undiagnostic of moral character. Studies 1 and 2 revealed that employees with low moral character committed harmful work behaviors more frequently and helpful work behaviors less frequently than did employees with high moral character, according to their own admissions and coworkers' observations. Study 3 revealed that adults with low moral character committed more delinquent behavior and had more lenient attitudes toward unethical negotiation tactics than did adults with high moral character. By showing that individual differences have consistent, meaningful effects on employees' behaviors, after controlling for demographic variables (e.g., gender, age, income) and basic attributes of the work setting (e.g., enforcement of an ethics code), our results contest situationist perspectives that deemphasize the importance of personality. Moral people can be identified by self-reports in surveys, and these self-reports predict consequential behaviors months after the initial assessment.

  14. Inverse scale space decomposition

    DEFF Research Database (Denmark)

    Schmidt, Marie Foged; Benning, Martin; Schönlieb, Carola-Bibiane

    2018-01-01

    We investigate the inverse scale space flow as a decomposition method for decomposing data into generalised singular vectors. We show that the inverse scale space flow, based on convex and even and positively one-homogeneous regularisation functionals, can decompose data represented...... by the application of a forward operator to a linear combination of generalised singular vectors into its individual singular vectors. We verify that for this decomposition to hold true, two additional conditions on the singular vectors are sufficient: orthogonality in the data space and inclusion of partial sums...... of the subgradients of the singular vectors in the subdifferential of the regularisation functional at zero. We also address the converse question of when the inverse scale space flow returns a generalised singular vector given that the initial data is arbitrary (and therefore not necessarily in the range...

  15. 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.

  16. Decomposition mechanisms of tertiarybutylarsine

    Science.gov (United States)

    Larsen, C. A.; Buchan, N. I.; Li, S. H.; Stringfellow, G. B.

    1989-03-01

    As a new source compound to replace AsH 3 for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors, tertiarybutylarsine (TBAs) has the advantages of low decomposition temperatures, lower safety hazards, and low carbon contamination in OMVPE grown GaAs layers. The vapor pressure of TBAs was measured, and is given by log 10P( Torr) = 7.500 - 1562.3/ T( K). The decomposition mechanisms of TBAs were studied in a D 2 ambient using a time-of-flight mass spectrometer to analyze the gaseous products. Although a free radical mechanisms would seem the most likely, it is not the dominant route for decomposition. Instead, unimolecular processes are the preferred pathway. Two such reactions are proposed. The major step is intramolecular coupling yielding AsH and isobutane. At higher temperatures β-elimination becomes important, producing AsH 3 and isobutene. The reactions are catalyzed by GaAs surfaces, but not by silica. The temperature dependence of the reaction rates was studied, and Arrhenius parameters for the rate constants are given.

  17. THERMAL EXPANSION BEHAVIOR OF THE Ba0.2Sr0.8Co0.8Fe0.2O3−δ (BSCF) WITH Sm0.2Ce0.8O1.9

    OpenAIRE

    M. AHMADREZAEI; S. A. MUHAMMED ALI; A. MUCHTAR; C.Y.TAN; M.R. SOMALU

    2014-01-01

    Nanostructured perovskite oxides of Ba0.2Sr0.8Co0.8Fe0.2O3−δ (BSCF) were synthesized through the co-precipitation method. The thermal decomposition, phase formation and thermal expansion behavior of BSCF were characterized by thermogravimetric analysis, X-ray diffraction (XRD), and dilatometry, respectively. XRD peaks were indexed to a cubic perovskite structure with a Pm3m (221) space group. All the combined oxides produced the desired perovskite-phase BSCF. The microstructures were characte...

  18. Factorized combinations of Virasoro characters

    International Nuclear Information System (INIS)

    Bytsko, A.G.; Fring, A.

    2000-01-01

    We investigate linear combinations of characters for minimal Virasoro models which are representable as a product of several basic blocks. Our analysis is based on consideration of asymptotic behaviour of the characters in the quasi-classical limit. In particular, we introduce a notion of the secondary effective central charge. We find all possible cases for which factorization occurs on the base of the Gauss-Jacobi or the Watson identities. Exploiting these results, we establish various types of identities between different characters. In particular, we present several identities generalizing the Rogers-Ramanujan identities. Applications to quasi-particle representations, modular invariant partition functions, super-conformal theories and conformal models with boundaries are briefly discussed. (orig.)

  19. 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.

  20. Introducing Character Animation with Blender

    CERN Document Server

    Mullen, Tony

    2011-01-01

    Introducing Character Animation with Blender, 2nd Edition is written in a friendly but professional tone, with clear descriptions and numerous illustrative screenshots. Throughout the book, tutorials focus on how to accomplish actual animation goals, while illustrating the necessary technical methods along the way. These are reinforced by clear descriptions of how each specific aspect of Blender works and fits together with the rest of the package. By following all the tutorials, the reader will gain all the skills necessary to build and animate a well-modeled, fully-rigged character of their

  1. In situ solid state 11B MAS-NMR studies of the thermal decomposition of ammonia borane: mechanistic studies of the hydrogen release pathways from a solid state hydrogen storage material.

    Science.gov (United States)

    Stowe, Ashley C; Shaw, Wendy J; Linehan, John C; Schmid, Benjamin; Autrey, Tom

    2007-04-21

    The mechanism of hydrogen release from solid state ammonia borane (AB) has been investigated via in situ solid state (11)B and (11)B{(1)H} MAS-NMR techniques in external fields of 7.1 T and 18.8 T at a decomposition temperature of 88 degrees C, well below the reported melting point. The decomposition of AB is well described by an induction, nucleation and growth mechanistic pathway. During the induction period, little hydrogen is released from AB; however, a new species identified as a mobile phase of AB is observed in the (11)B NMR spectra. Subsequent to induction, at reaction times when hydrogen is initially being released, three additional species are observed: the diammoniate of diborane (DADB), [(NH(3))(2)BH(2)](+)[BH(4)](-), and two BH(2)N(2) species believed to be the linear (NH(3)BH(2)NH(2)BH(3)) and cyclic dimer (NH(2)BH(2))(2) of aminoborane. At longer reaction times the sharper features are replaced by broad, structureless peaks of a complex polymeric aminoborane (PAB) containing both BH(2)N(2) and BHN(3) species. The following mechanistic model for the induction, nucleation and growth for AB decomposition leading to formation of hydrogen is proposed: (i) an induction period that yields a mobile phase of AB caused by disruption of the dihydrogen bonds; (ii) nucleation that yields reactive DADB from the mobile AB; and (iii) growth that includes a bimolecular reaction between DADB and AB to release the stored hydrogen.

  2. Catalytic Decomposition of Hydroxylammonium Nitrate Ionic Liquid: Enhancement of NO Formation

    Science.gov (United States)

    2017-04-24

    9 any NO formation was attributed to its possible formation from decomposition of HNO2 or HNO3. The addition of acetate anion retarded HAN...Boatz, J. A.; Vaghjiani, G. L.; Koh, C.; Kostko, O.; Golan, A.; Leone, S. R. Thermal Decomposition of 1- Ethyl -3-methylimidazolium Bromide Ionic Liquid

  3. Building Character through Literacy with Children's Literature

    Science.gov (United States)

    Almerico, Gina M.

    2014-01-01

    Character education is described as curriculum specifically developed to teach children about the quality and traits of good character. One means in which children can learn about good character is through the pages of high quality children's literature. In this study, the author defines the characteristics of an effective character development…

  4. An Historical Analysis of Character Education

    Science.gov (United States)

    Watz, Michael

    2011-01-01

    What is termed "character education" in today's world has been called many things throughout the history of education in this country. Character education has been both a formal and informal part of schools. Much of character education in the United States can be closely tied in its roots to the education of character in Europe, which…

  5. Understanding Agency and Educating Character

    Science.gov (United States)

    Roth, Klas

    2011-01-01

    How can we understand human agency, and what does it mean to educate character? In this essay Klas Roth develops a Kantian notion, one that suggests we render ourselves efficacious and autonomous in education and elsewhere. This requires, among other things, that we are successful in bringing about the intended result through our actions and the…

  6. Recognition of isolated handprinted characters

    DEFF Research Database (Denmark)

    Martins, Bo

    1996-01-01

    Handprinted characters are of unequal complexity and a common description of all alphabet symbols seems therefore unobtainable. However, letters which confuse human beings and man-made OCR systems usually have approximately the same appearance and may therefore be modeled jointly. We part the set...

  7. 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....

  8. 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

  9. Hydrogen peroxide catalytic decomposition

    Science.gov (United States)

    Parrish, Clyde F. (Inventor)

    2010-01-01

    Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

  10. Coupling of temperature with pressure induced initial decomposition ...

    Indian Academy of Sciences (India)

    and 116 atoms, figure 1) and a 1 × 2 × 1 super- cell (8 molecules and 88 atoms, figure 1) respectively. First, the system was equilibrated at 298.15 K for 5 ps using NVT. Then, based on this equilibrated system, for. PETN, at 475 K (thermal decomposition temperature),. AIMD simulations were carried out using NPT at 1, 2,.

  11. 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...... procedure with the dual variables....

  12. Decomposition kinetics of expanded austenite with high nitrogen contents

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    ) 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...

  13. 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.

  14. Thermal maturity patterns in Pennsylvanian coal-bearing rocks in Alabama, Tennessee, Kentucky, Virginia, West Virginia, Ohio, Maryland, and Pennsylvania: Chapter F.2 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Ruppert, Leslie F.; Trippi, Michael H.; Hower, James C.; Grady, William C.; Levine, Jeffrey R.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    Thermal maturation patterns of Pennsylvanian strata in the Appalachian basin and part of the Black Warrior basin were determined by compiling previously published and unpublished percent-vitrinite-reflectance (%R0) measurements and preparing isograd maps on the basis of the measurements. The isograd values range from 0.6 %R0 in Ohio and the western side of the Eastern Kentucky coal field to 5.5 %R0 in the Southern field in the Pennsylvania Anthracite region, Schuylkill County, Pa. The vitrinite-reflectance values correspond to the American Society of Testing Materials (ASTM) coal-rank classes of high-volatile C bituminous to meta-anthracite, respectively. In general, the isograds show that thermal maturity patterns of Pennsylvanian coals within the Appalachian basin generally decrease from east to west. In the Black Warrior basin of Alabama, the isograds show a circular pattern with the highest values (greater than 1.6 %R0) centered in Jefferson County, Ala. Most of the observed patterns can be explained by variations in the depth of burial, variations in geothermal gradient, or a combination of both; however, there are at least four areas of higher ranking coal in the Appalachian basin that are difficult to explain by these two processes alone: (1) a set of west- to northwest-trending salients centered in Somerset, Cambria, and Fayette Counties, Pa.; (2) an elliptically shaped, northeast-trending area centered in southern West Virginia and western Virginia; (3) the Pennsylvania Anthracite region in eastern Pennsylvania; and (4) the eastern part of the Black Warrior coal field in Alabama. The areas of high-ranking coal in southwestern Pennsylvania, the Black Warrior coal field, and the Pennsylvania Anthracite region are interpreted here to represent areas of higher paleo-heat flow related to syntectonic movement of hot fluids towards the foreland associated with Alleghanian deformation. In addition to the higher heat flow from these fluids, the Pennsylvania

  15. On characters of finite groups

    CERN Document Server

    Broué, Michel

    2017-01-01

    This book explores the classical and beautiful character theory of finite groups. It does it by using some rudiments of the language of categories. Originally emerging from two courses offered at Peking University (PKU), primarily for third-year students, it is now better suited for graduate courses, and provides broader coverage than books that focus almost exclusively on groups. The book presents the basic tools, notions and theorems of character theory (including a new treatment of the control of fusion and isometries), and introduces readers to the categorical language at several levels. It includes and proves the major results on characteristic zero representations without any assumptions about the base field. The book includes a dedicated chapter on graded representations and applications of polynomial invariants of finite groups, and its closing chapter addresses the more recent notion of the Drinfeld double of a finite group and the corresponding representation of GL_2(Z).

  16. A note on generalized characters

    Indian Academy of Sciences (India)

    Abstract. For a compactly generated LCA group G, it is shown that the set H (G) of all generalized characters on G equipped with the compact-open topology is a LCA group and H (G) = ̂G (the dual group of G) if and only if G is compact. Both results fail for arbitrary LCA groups. Further, if G is second countable, then the ...

  17. Modeling Decomposition of Unconfined Rigid Polyurethane Foam

    Energy Technology Data Exchange (ETDEWEB)

    CHU,TZE YAO; ERICKSON,KENNETH L.; HOBBS,MICHAEL L.

    1999-11-01

    The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam which contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.

  18. Modeling Decomposition of Unconfined Rigid Polyurethane Foam

    Energy Technology Data Exchange (ETDEWEB)

    HOBBS,MICHAEL L.; ERICKSON,KENNETH L.; CHU,TZE YAO

    1999-11-08

    The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam that contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.

  19. Chemical decomposition of water into hydrogen in heterogeneous aluminum-containing compositions

    International Nuclear Information System (INIS)

    Milinchuk, V.K.; Belozerov, V.I.; Anan'eva, O.A.; Laricheva, T.E.; Kunitsyna, T.E.

    2014-01-01

    Authors investigate the kinetic regularities and mechanism of chemical decomposition of water into hydrogen in heterogeneous hydro-reactive systems, containing aluminum, aluminum alloys, and such chemical compounds as liquid sodium glass or quicklime giving a water solution an alkaline character [ru

  20. A study of SiC decomposition under laser irradiation

    Science.gov (United States)

    Adelmann, B.; Hellmann, R.

    2017-06-01

    In this experimental study we investigate the laser induced thermal decomposition of 4H-Sic under ambient conditions using fiber laser. Using a unique two-color pyrometer setup, we measure the temporal evolution of the temperature in the irradiated zone and determine the decomposition rate for various laser power levels. We find that the temporal evolution of the temperature in the irradiated area exhibits an initial heating phase up to about 1300 K, being characterized by an unaffected SiC surface. Upon an expeditious temperature increase, a decomposition phase follows with temperatures above 1700 K, being accompanied by carbonization of the SiC surface. The decomposed volume depends linearly on the duration of the decomposition phase and increases linearly with laser power. The temperature evaluation of the decomposition speed reveals an Arrhenius-type behavior allowing the calculation of the activation energy for the decomposition under ambient conditions to 613 kJ/mol in the temperature range between 2140 and 2420 K.

  1. Thermodynamic anomaly in magnesium hydroxide decomposition

    International Nuclear Information System (INIS)

    Reis, T.A.

    1983-08-01

    The Origin of the discrepancy in the equilibrium water vapor pressure measurements for the reaction Mg(OH) 2 (s) = MgO(s) + H 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 -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) 2 used as a starting material, which confirms the inferences of Kay and Gregory. Thus, most forms of Mg(OH) 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 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) 2 -MgO solid solution during continuous thermal decomposition in Knudsen cells

  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. A Combined Theoretical and Experimental Study of Sarin (GB) Decomposition at High Temperatures.

    Science.gov (United States)

    Shan, Xiao; Vincent, Jack C; Kirkpatrick, Sue; Walker, Maurice D; Sambrook, Mark R; Clary, David C

    2017-08-24

    Theoretical and experimental results are presented for the pyrolytic decomposition of the nerve agent sarin (GB) in the gas phase. High-level quantum chemistry calculations are performed together with a semiclassical transition-state theory for describing quantum mechanical tunneling. The experimental and theoretical results for the temperature dependence of the survival times show very good agreement, as does the calculated and measured activation energy for thermal decomposition. The combined results suggest that the thermal decomposition of GB, for temperature ranging from 350 to 500 °C, goes through a pericyclic reaction mechanism with a transition state consisting of a six-membered ring structure.

  4. Character Education and Students Social Behavior

    OpenAIRE

    A. Kamaruddin, Syamsu

    2012-01-01

    In an educational environment, in the form of character education program has been done both formally and informally. It's intended as one of the supporting ideas for follow-up in the form of design activities. Character education should basically refers to the vision and mission of the institution concerned. It shows the orientation of the two things in the character of the students are: aspects of human character and individual learners hallmark institution. In this paper, these tw...

  5. Preparation, Characterization, Thermal, and Flame-Retardant Properties of Green Silicon-Containing Epoxy/Functionalized Graphene Nanosheets Composites

    Directory of Open Access Journals (Sweden)

    Ming-Yuan Shen

    2013-01-01

    Full Text Available In this investigation, silane was grafted onto the surface of graphene nanosheets (GNSs through free radical reactions, to form Si-O-Et functional groups that can undergo the sol-gel reaction. To improve the compatibility between the polymer matrix and the fillers, epoxy monomer was modified using a silane coupling agent; then, the functionalized GNSs were added to the modified epoxy to improve the thermal stability and strengthen the flame-retardant character of the composites. High-resolution X-ray photoelectron spectrometry reveals that when the double bonds in VTES are grafted to the surfaces of GNSs. Solid-state 29Si nuclear magnetic resonance presents that the distribution of the signal associated with the T3 structure is wide and significant, indicating that the functionalization reaction of the silicone in the modified epoxy and VTES-GNSs increases the network-like character of the structures. Thermal gravimetric analysis, the integral procedure decomposition temperature, and limiting oxygen index demonstrate that the GNSs composites that contained silicon had a higher thermal stability and stronger flame-retardant character than pure epoxy. The dynamic storage modulus of all of the m-GNSs containing composites was significantly higher than that of the control epoxy, and the modulus of the composites increased with the concentration of m-GNSs.

  6. Character Balance in MOBA Games

    OpenAIRE

    Teodor, Norén; Emanuel, Palm

    2015-01-01

    As live streaming of video games has become easier, electronic sports have grown quickly and they are still increasing as tournaments grow in viewers and prizes. The purpose of this paper is to examine the theory Metagame Bounds by applying it to League of Legends and Dota 2, to see if it is a valid way of looking at character balance in the Multiplayer Online Battle Arena game genre. The main mode of both games consist of matches played on a map where a team of five players is up against ano...

  7. A Review of Virtual Character's Emotion Model

    Science.gov (United States)

    Liu, Zhen

    2008-11-01

    Emotional virtual characters are essential to digital entertainment, an emotion is related to virtual environment and a virtual character's inner variables, emotion model of virtual character is a hot topic in many fields, domain knowledge is very important for modeling emotion, and the current research of emotion expression in the world was also summarized, and some new research directions of emotion model are presented.

  8. Understanding the Properties of Interactive Televised Characters

    Science.gov (United States)

    Claxton, Laura J.; Ponto, Katelyn C.

    2013-01-01

    Children's television programming frequently uses interactive characters that appear to directly engage the viewers. These characters encourage children to answer questions and perform actions to help the characters solve problems in the televised world. Children readily engage in these interactions; however, it is unclear why they do so. To…

  9. Is There a Place for Character Education?

    Science.gov (United States)

    Creasy, Kim L.

    2008-01-01

    Recent trends in school curricula place a heavy focus on the improvement of basic skills test scores. As a result, the role of character education has been diminished. This article provides a rationale for the incorporation of a character education program within the school curricula, a working definition of character education, and the role of…

  10. Promoting Character Development through Coach Education

    Science.gov (United States)

    Power, F. Clark; Seroczynski, A. D.

    2015-01-01

    Can youth sports build character? Research suggests that the answer to this question leads to 2 further questions: (1) can youth sport coaches be effectively prepared to become character educators, and (2) can character education take place in today's competitive youth sport environment? (Bredemeier & Shields, 2006; Power, 2015; Power &…

  11. AMHARIC CHARACTER GENERATOR Gebre Amanuel Gessesse ...

    African Journals Online (AJOL)

    usually a visual display terminal (VDT); file storage ... character code into a visual image of the character. Several techniques ... Memory ll 7'. In the second alternative considered, the complete syllabary with punctuation marks and numerals is put within one character generator. The font selected is show in Fig. 1. The matrix.

  12. AUTONOMOUS GAUSSIAN DECOMPOSITION

    International Nuclear Information System (INIS)

    Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian; Heiles, Carl; Hennebelle, Patrick; Goss, W. M.; Dickey, John

    2015-01-01

    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

  13. 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.

  14. 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.

  15. Decomposition of tetrafluoromethane by water plasma generated under atmospheric pressure

    International Nuclear Information System (INIS)

    Narengerile,; Saito, Hironori; Watanabe, Takayuki

    2009-01-01

    Tetrafluoromethane (CF 4 ) decomposition by water plasma generated under atmospheric pressure was investigated by means of thermodynamic analyses and experiments. Thermodynamic equilibrium calculations were performed between 300 and 6000 K at atmospheric pressure. Experimental results indicated that CF 4 was completely decomposed by water plasma, and recovery of fluorine can be achieved more than 99%. Influence of factors such as arc current and additive flow rate of O 2 on CF 4 decomposition was determined. Furthermore, the decomposition mechanism of CF 4 was investigated from chemical kinetics consideration. CF x(x:1-4) was thermally decomposed above 4000 K, oxidized in the temperature range of 4000-2400 K, and removed by H radical at temperatures below 2400 K.

  16. Decomposition of tetrafluoromethane by water plasma generated under atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Narengerile,; Saito, Hironori [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8502 (Japan); Watanabe, Takayuki, E-mail: watanabe@chemenv.titech.ac.j [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8502 (Japan)

    2009-12-01

    Tetrafluoromethane (CF{sub 4}) decomposition by water plasma generated under atmospheric pressure was investigated by means of thermodynamic analyses and experiments. Thermodynamic equilibrium calculations were performed between 300 and 6000 K at atmospheric pressure. Experimental results indicated that CF{sub 4} was completely decomposed by water plasma, and recovery of fluorine can be achieved more than 99%. Influence of factors such as arc current and additive flow rate of O{sub 2} on CF{sub 4} decomposition was determined. Furthermore, the decomposition mechanism of CF{sub 4} was investigated from chemical kinetics consideration. CF{sub x(x:1-4)} was thermally decomposed above 4000 K, oxidized in the temperature range of 4000-2400 K, and removed by H radical at temperatures below 2400 K.

  17. Theoretical and experimental study: the size dependence of decomposition thermodynamics of nanomaterials

    International Nuclear Information System (INIS)

    Cui, Zixiang; Duan, Huijuan; Li, Wenjiao; Xue, Yongqiang

    2015-01-01

    In the processes of preparation and application of nanomaterials, the decomposition reactions of nanomaterials are often involved. However, there is a dramatic difference in decomposition thermodynamics between nanomaterials and the bulk counterparts, and the difference depends on the size of the particles that compose the nanomaterials. In this paper, the decomposition model of a nanoparticle was built, the theory of decomposition thermodynamics of nanomaterials was proposed, and the relations of the size dependence of thermodynamic quantities for the decomposition reactions were deduced. In experiment, taking the thermal decomposition of nano-Cu 2 (OH) 2 CO 3 with different particle sizes (the range of radius is at 8.95–27.4 nm) as a system, the reaction thermodynamic quantities were determined, and the regularities of size dependence of the quantities were summarized. These experimental regularities consist with the above thermodynamic relations. The results show that there is a significant effect of the size of particles composing a nanomaterial on the decomposition thermodynamics. When all the decomposition products are gases, the differences in thermodynamic quantities of reaction between the nanomaterials and the bulk counterparts depend on the particle size; while when one of the decomposition products is a solid, the differences depend on both the initial particle size of the nanoparticle and the decomposition ratio. When the decomposition ratio is very small, these differences are only related to the initial particle size; and when the radius of the nanoparticles approaches or exceeds 10 nm, the reaction thermodynamic functions and the logarithm of the equilibrium constant are linearly associated with the reciprocal of radius, respectively. The thermodynamic theory can quantificationally describe the regularities of the size dependence of thermodynamic quantities for decomposition reactions of nanomaterials, and contribute to the researches and the

  18. Theoretical and experimental study: the size dependence of decomposition thermodynamics of nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zixiang; Duan, Huijuan; Li, Wenjiao; Xue, Yongqiang, E-mail: xyqlw@126.com [Taiyuan University of Technology, Department of Applied Chemistry (China)

    2015-07-15

    In the processes of preparation and application of nanomaterials, the decomposition reactions of nanomaterials are often involved. However, there is a dramatic difference in decomposition thermodynamics between nanomaterials and the bulk counterparts, and the difference depends on the size of the particles that compose the nanomaterials. In this paper, the decomposition model of a nanoparticle was built, the theory of decomposition thermodynamics of nanomaterials was proposed, and the relations of the size dependence of thermodynamic quantities for the decomposition reactions were deduced. In experiment, taking the thermal decomposition of nano-Cu{sub 2}(OH){sub 2}CO{sub 3} with different particle sizes (the range of radius is at 8.95–27.4 nm) as a system, the reaction thermodynamic quantities were determined, and the regularities of size dependence of the quantities were summarized. These experimental regularities consist with the above thermodynamic relations. The results show that there is a significant effect of the size of particles composing a nanomaterial on the decomposition thermodynamics. When all the decomposition products are gases, the differences in thermodynamic quantities of reaction between the nanomaterials and the bulk counterparts depend on the particle size; while when one of the decomposition products is a solid, the differences depend on both the initial particle size of the nanoparticle and the decomposition ratio. When the decomposition ratio is very small, these differences are only related to the initial particle size; and when the radius of the nanoparticles approaches or exceeds 10 nm, the reaction thermodynamic functions and the logarithm of the equilibrium constant are linearly associated with the reciprocal of radius, respectively. The thermodynamic theory can quantificationally describe the regularities of the size dependence of thermodynamic quantities for decomposition reactions of nanomaterials, and contribute to the

  19. Group discriminatory power of handwritten characters

    Science.gov (United States)

    Tomai, Catalin I.; Kshirsagar, Devika M.; Srihari, Sargur N.

    2003-12-01

    Using handwritten characters we address two questions (i) what is the group identification performance of different alphabets (upper and lower case) and (ii) what are the best characters for the verification task (same writer/different writer discrimination) knowing demographic information about the writer such as ethnicity, age or sex. The Bhattacharya distance is used to rank different characters by their group discriminatory power and the k-nn classifier to measure the individual performance of characters for group identification. Given the tasks of identifying the correct gender/age/ethnicity or handedness, the accumulated performance of characters varies between 65% and 85%.

  20. Body Language Advanced 3D Character Rigging

    CERN Document Server

    Allen, Eric; Fong, Jared; Sidwell, Adam G

    2011-01-01

    Whether you're a professional Character TD or just like to create 3D characters, this detailed guide reveals the techniques you need to create sophisticated 3D character rigs that range from basic to breathtaking. Packed with step-by-step instructions and full-color illustrations, Body Language walks you through rigging techniques for all the body parts to help you create realistic and believable movements in every character you design. You'll learn advanced rigging concepts that involve MEL scripting and advanced deformation techniques and even how to set up a character pipeline.

  1. Data set for Tifinagh handwriting character recognition

    Directory of Open Access Journals (Sweden)

    Omar Bencharef

    2015-09-01

    Full Text Available The Tifinagh alphabet-IRCAM is the official alphabet of the Amazigh language widely used in North Africa [1]. It includes thirty-one basic letter and two letters each composed of a base letter followed by the sign of labialization. Normalized only in 2003 (Unicode [2], ICRAM-Tifinagh is a young character repertoire. Which needs more work on all levels. In this context we propose a data set for handwritten Tifinagh characters composed of 1376 image; 43 Image For Each character. The dataset can be used to train a Tifinagh character recognition system, or to extract the meaning characteristics of each character.

  2. Data set for Tifinagh handwriting character recognition.

    Science.gov (United States)

    Bencharef, Omar; Chihab, Younes; Mousaid, Nouredine; Oujaoura, Mustapha

    2015-09-01

    The Tifinagh alphabet-IRCAM is the official alphabet of the Amazigh language widely used in North Africa [1]. It includes thirty-one basic letter and two letters each composed of a base letter followed by the sign of labialization. Normalized only in 2003 (Unicode) [2], ICRAM-Tifinagh is a young character repertoire. Which needs more work on all levels. In this context we propose a data set for handwritten Tifinagh characters composed of 1376 image; 43 Image For Each character. The dataset can be used to train a Tifinagh character recognition system, or to extract the meaning characteristics of each character.

  3. 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

  4. 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...

  5. 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.

  6. Professional Development for Character Education: An Evaluation of Teachers' Sense of Efficacy for Character Education

    Science.gov (United States)

    Ledford, Alice T.

    2011-01-01

    Today's teachers and administrators must educate students for character. But, teachers are inconsistently prepared for this challenge. This descriptive study examined teachers' sense of efficacy for character education among pre-K-12 teachers based on their type of character education training. The Character Education Efficacy Belief Instrument…

  7. Handwritten Sindhi Character Recognition Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Shafique Ahmed Awan

    2018-01-01

    Full Text Available OCR (OpticalCharacter Recognition is a technology in which text image is used to understand and write text by machines. The work on languages containing isolated characters such as German, English, French and others is at its peak. The OCR and ICR (Intelligent Character Recognition research in Sindhi script is currently at in starting stages and not sufficient work have been cited in this area even though Sindhi language is rich in culture and history. This paper presents one of the initial steps in recognizing Sindhi handwritten characters. The isolated characters of Sindhi script written by thesubjects have been recognized. The various subjects were asked to write Sindhi characters in unconstrained form and then the written samples were collected and scanned through a flatbed scanner. The scanned documents were preprocessedwith the help of binary conversion, removing noise by pepper noise and the lines were segmented with the help of horizontal profile technique. The segmented lines were used to extract characters from scanned pages.This character segmentation was done by vertical projection. The extracted characters have been used to extract features so that the characters can be classified easily. Zoning was used for the feature extraction technique. For the classification, neural network has been used. The recognized characters converted into editable text with an average accuracy of 85%.

  8. Marvel and DC Characters Inspired by Arachnids

    Directory of Open Access Journals (Sweden)

    Elidiomar Ribeiro Da-Silva

    2014-12-01

    Full Text Available This article compares arachnid-based Marvel and DC comics characters. The composition of a comic book character often has interesting ‘real-life’ influences. Given the strong connection between arachnids (especially spiders, scorpions and mites, all belonging to the zoological class 'Arachnida' and human beings it is not surprising that they have inspired many fictional characters. We recorded 84 Marvel Comics characters and 40 DC Comics characters, detailed in the dataset that accompanies the article (Da-Silva 2014. Most characters have been created recently, since the 1990s. Marvel has significantly more arachnid characters than DC. As for taxonomic classification, the characters were based mostly on spiders (zoological order 'Araneae'. Of the total characters, the majority are human beings, but an overwhelming number have at least some typical arachnid features. Villains (60.91% of total are significantly more numerous, considering the sum of the two publishers. Arachnids have bad reputation for being dangerous (Thorp and Woodson 1976; Ruppert and Barnes 1996. Since the public usually considers spiders, scorpions and mites “harmful” in general, we expected a larger contingent of villains. However, there was no statistical difference between the amount of villains and heroes in Marvel characters. It did not happen probably due to the success of one character: the Amazing Spider-Man.

  9. 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.)

  10. Kannada character recognition system using neural network

    Science.gov (United States)

    Kumar, Suresh D. S.; Kamalapuram, Srinivasa K.; Kumar, Ajay B. R.

    2013-03-01

    Handwriting recognition has been one of the active and challenging research areas in the field of pattern recognition. It has numerous applications which include, reading aid for blind, bank cheques and conversion of any hand written document into structural text form. As there is no sufficient number of works on Indian language character recognition especially Kannada script among 15 major scripts in India. In this paper an attempt is made to recognize handwritten Kannada characters using Feed Forward neural networks. A handwritten Kannada character is resized into 20x30 Pixel. The resized character is used for training the neural network. Once the training process is completed the same character is given as input to the neural network with different set of neurons in hidden layer and their recognition accuracy rate for different Kannada characters has been calculated and compared. The results show that the proposed system yields good recognition accuracy rates comparable to that of other handwritten character recognition systems.

  11. Character animation fundamentals developing skills for 2D and 3D character animation

    CERN Document Server

    Roberts, Steve

    2012-01-01

    Expand your animation toolkit and remain competitive in the industry with this leading resource for 2D and 3D character animation techniques. Apply the industry's best practices to your own workflows and develop 2D, 3D and hybrid characters with ease. With side by side comparisons of 2D and 3D character design, improve your character animation and master traditional principles and processes including weight and balance, timing and walks. Develop characters inspired by humans, birds, fish, snakes and four legged animals. Breathe life into your character and develop a characters personality w

  12. 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.

  13. Synthetic biology character and impact

    CERN Document Server

    Pade, Christian; Wigger, Henning; Gleich, Arnim

    2015-01-01

    Synthetic Biology is already an object of intensive debate. However, to a great extent the discussion to date has been concerned with fundamental ethical, religious and philosophical questions. By contrast, based on an investigation of the field’s scientific and technological character, this book focuses on new functionalities provided by synthetic biology and explores the associated opportunities and risks. Following an introduction to the subject and a discussion of the most central paradigms and methodologies, the book provides an overview of the structure of this field of science and technology. It informs the reader about the current stage of development, as well as topical problems and potential opportunities in important fields of application. But not only the science itself is in focus. In order to investigate its broader impact, ecological as well as ethical implications will be considered, paving the way for a discussion of responsibilities in the context of a field at a transitional crossroads be...

  14. Kinetics of the decomposition reaction of phosphorite concentrate

    Directory of Open Access Journals (Sweden)

    Huang Run

    2014-01-01

    Full Text Available Apatite is the raw material, which is mainly used in phosphate fertilizer, and part are used in yellow phosphorus, red phosphorus, and phosphoric acid in the industry. With the decrease of the high grade phosphorite lump, the agglomeration process is necessary for the phosphorite concentrate after beneficiation process. The decomposition behavior and the phase transformation are of vital importance for the agglomeration process of phosphorite. In this study, the thermal kinetic analysis method was used to study the kinetics of the decomposition of phosphorite concentrate. The phosphorite concentrate was heated under various heating rate, and the phases in the sample heated were examined by the X-ray diffraction method. It was found that the main phases in the phosphorite are fluorapatiteCa5(PO43F, quartz SiO2,and dolomite CaMg(CO32.The endothermic DSC peak corresponding to the mass loss caused by the decomposition of dolomite covers from 600°C to 850°C. The activation energy of the decomposition of dolomite, which increases with the increase in the extent of conversion, is about 71.6~123.6kJ/mol. The mechanism equation for the decomposition of dolomite agrees with the Valensi equation and G-B equation.

  15. 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

    A pulse radiolysis technique has been used to measure a rate constant of (6.6 +/- 1.3) x 10(-12) cm3 molecule-1 s-1 for the association reaction between CF3C(O)O2 radicals and NO2 at 295 K and one atmosphere total pressure of SF6 diluent. A FTIR/smog chamber system was used to study the thermal...

  16. Hydrocarbon decomposition kinetics on the Ir(111) surface.

    Science.gov (United States)

    Tetlow, H; Curcio, D; Baraldi, A; Kantorovich, L

    2018-02-28

    The kinetics of the thermal decomposition of hydrocarbons on the Ir(111) surface is determined using kinetic Monte Carlo (kMC) and rate equations simulations, both based on the density functional theory (DFT) calculated energy barriers of the involved reaction processes. This decomposition process is important for understanding the early stages of epitaxial graphene growth where the deposited hydrocarbon acts as a carbon feedstock for graphene formation. The methodology of the kMC simulations and the rate equation approaches is discussed and a comparison between the results obtained from both approaches is made in the case of the temperature programmed decomposition of ethylene for different initial coverages. The theoretical results are verified against experimental data from in situ X-ray photoelectron spectroscopy (XPS) experiments. Both theoretical approaches give reasonable results; however we find that, as expected, rate equations are less reliable at high coverages. We find that the agreement between experiment and theory can be improved in all cases if slight adjustments are made to the energy barriers in order to account for the intrinsic errors in DFT. Finally we extend our approach to the case where hydrocarbon species are dosed onto the substrate continuously, as in the chemical vapour deposition (CVD) graphene growth method. For ethylene and methane the thermal decomposition mechanism is determined, and it is found that in both cases the formation of C monomers is to be expected, which is limited by the presence of hydrogen atoms.

  17. [Analysis of the character of film decomposition of starch acetate (SA) coated urea by infrared spectrum].

    Science.gov (United States)

    Li, Dong-Po; Wu, Zhi-Jie; Liang, Cheng-Hua; Chen, Li-Jun; Zhang, Yu-Lan; Nie, Yan-Xia

    2012-06-01

    The degradability characteristics of film with 4 kinds of starch acetate coated and inhibitors amended urea were analyzed by FTIR, which was purposed to supply theoretical basis for applying starch acetate coated urea fertilizers in farming. The result showed that the chemical component, molecule structure and material form of the membrane were not changed because of adding different inhibitors to urea. The main peaks of the film degradation process were brought by the H--O, --OH, CO2, C==O, --CH2, --CH3, C--O, C--O--H and C--O--C vibrancy in asymmetry and symmetry. In brown soil, the trend of absorbing value of the most high peak was 0>15>30>60>90>120>150>310 d. The infrared spectra of 4 kinds of fertilizers were not different remarkably, and the film was comparatively slowly degraded before 15 d. But a majority of the film had been already degraded after 150 days. The main components of film materials were degraded fastest in 310 days. The speed of film degradation wasn't more impacted by different inhibitors. The characteristic of starch acetate film degradation may be monitored entirely and degradation speed difference of the film could be represented through infrared spectrum.

  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. 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 ...

  20. The characters of radiation fields and effects for protection monitoring in nuclear-powered submarine

    International Nuclear Information System (INIS)

    Wang Yuexing; Ma Xiaoling; Lu Yongjie; Zhang Jianguo

    1999-01-01

    The characters of the radiation fields in nuclear-powered submarine have been described. The characters are: the range of γ-rays energy is from 0 to 10 MeV, there are thermal and fast neutrons in it, and space changes of energy spectra and flux rates for γ-rays and neutrons are rapid. The characters have markedly an effect on the design of individual dosimeter measuring neutron dose, on evaluating accident-dose, and on the calibration of the instruments used to radiation protection in nuclear-powered submarine