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Sample records for thermal decomposition kinetics

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

    Science.gov (United States)

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

    2014-12-01

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

  2. Kinetics of lithium peroxide monohydrate thermal decomposition

    Science.gov (United States)

    Nefedov, Roman; Posternak, Nikolay; Ferapontov, Yuriy

    2017-11-01

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

  3. 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.

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

    OpenAIRE

    Rueda-Ordóñez, Yesid Javier; Tannous, Katia

    2016-01-01

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

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

    Indian Academy of Sciences (India)

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

  6. 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 ...

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

    Indian Academy of Sciences (India)

    Unknown

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

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

    Science.gov (United States)

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

    2017-01-25

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

  10. 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.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-10

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

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

    Science.gov (United States)

    Nakano, Masayoshi; Wada, Takeshi; Koga, Nobuyoshi

    2015-09-24

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

  14. 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-...

  15. 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.

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

    Indian Academy of Sciences (India)

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

  17. 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.

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

    Science.gov (United States)

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

    2013-09-15

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

  20. 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

  1. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  3. 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.

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

    CERN Document Server

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

    2016-01-01

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

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

    Science.gov (United States)

    Rueda-Ordóñez, Yesid Javier; Tannous, Katia

    2016-07-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-11-22

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

  9. 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

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    Sen Guo

    2016-02-01

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

  12. 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.

  13. 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.

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

    Science.gov (United States)

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

    2017-12-27

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-02-01

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

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

    Science.gov (United States)

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

    2014-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-15

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

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

    Science.gov (United States)

    2016-03-14

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

  1. Thermal decomposition of hemicelluloses

    OpenAIRE

    Werner, Kajsa; Pommer, Linda; Broström, Markus

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

  3. 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

  4. 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.

  5. Thermal decomposition of illite

    Directory of Open Access Journals (Sweden)

    Araújo José Humberto de

    2004-01-01

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

  6. 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.

  7. Erbium hydride thermal desorption : controlling kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2007-08-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report show that hydride film processing parameters directly impact thermal stability. Issues to be addressed include desorption kinetics for dihydrides and trihydrides, and the effect of film growth parameters, loading parameters, and substrate selection on desorption kinetics.

  8. 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.

  9. Thermal decomposition of meat and bone meal

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-12-01

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

  10. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

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

  11. Decomposition kinetics of plutonium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, J.M.; Stakebake, J.L.

    1979-01-01

    Kinetic data for decomposition of PuH/sub 1/ /sub 95/ provides insight into a possible mechanism for the hydriding and dehydriding reactions of plutonium. The fact that the rate of the hydriding reaction, K/sub H/, is proportional to P/sup 1/2/ and the rate of the dehydriding process, K/sub D/, is inversely proportional to P/sup 1/2/ suggests that the forward and reverse reactions proceed by opposite paths of the same mechanism. The P/sup 1/2/ dependence of hydrogen solubility in metals is characteristic of the dissociative absorption of hydrogen; i.e., the reactive species is atomic hydrogen. It is reasonable to assume that the rates of the forward and reverse reactions are controlled by the surface concentration of atomic hydrogen, (H/sub s/), that K/sub H/ = c'(H/sub s/), and that K/sub D/ = c/(H/sub s/), where c' and c are proportionality constants. For this surface model, the pressure dependence of K/sub D/ is related to (H/sub s/) by the reaction (H/sub s/) reversible 1/2H/sub 2/(g) and by its equilibrium constant K/sub e/ = (H/sub 2/)/sup 1/2//(H/sub s/). In the pressure range of ideal gas behavior, (H/sub s/) = K/sub e//sup -1/(RT)/sup -1/2/ and the decomposition rate is given by K/sub D/ = cK/sub e/(RT)/sup -1/2/P/sup 1/2/. For an analogous treatment of the hydriding process with this model, it can be readily shown that K/sub H/ = c'K/sub e//sup -1/(RT)/sup -1/2/P/sup 1/2/. The inverse pressure dependence and direct temperature dependence of the decomposition rate are correctly predicted by this mechanism which is most consistent with the observed behavior of the Pu--H system.

  12. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    TECS

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

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

    Directory of Open Access Journals (Sweden)

    I.A. Adejoro

    2017-09-01

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

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

    Science.gov (United States)

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

    2018-01-01

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

  15. Thermal decomposition of ammonium hexachloroosmate

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2014-03-01

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

  18. 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.

  19. Decomposition kinetics of expanded austenite with high nitrogen contents

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    This paper addresses the decomposition kinetics of synthesized homogeneous expanded austenite formed by gaseous nitriding of stainless steel AISI 304L and AISI 316L with nitrogen contents up to 38 at.% nitrogen. Isochronal annealing experiments were carried out in both inert (N2) and reducing (H2......) atmospheres. Differential thermal analysis (DTA) and thermogravimetry were applied for identification of the decomposition reactions and X-ray diffraction analysis was applied for phase analysis. CrN precipitated upon annealing; the activation energies are 187 kJ/mol and 128 kJ/mol for AISI 316L and AISI 304L...

  20. Modeling yields insight into thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-01

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

  1. 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.

  2. Comparison of the thermal decomposition kinetics for charged LiMn{sub 2}O{sub 4} by TG and C80 methods

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qingsong [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China)], E-mail: pinew@ustc.edu.cn; Sun Jinhua [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China); Chen Dongliang [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 (China); College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Chen Chunhua [Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China)

    2009-01-22

    In order to disclose the decomposition kinetics of charged LiMn{sub 2}O{sub 4} used in lithium-ion batteries, thermogravimetric analyzer (TGA) and C80 micro-calorimeter were employed in this study. Three stages of weight loss were detected by TG and two main exothermic processes were detected by C80 micro-calorimeter for the charged LiMn{sub 2}O{sub 4}. The chemical reaction kinetics is supposed to fit by an Arrhenius law, and then the activation energy is calculated as E{sub a} = 90.4 and 140.1 kJ mol{sup -1} based on TG and C80 data, respectively. And the C80 method shows more advantages in studying the thermodynamic and kinetic parameters for both the electrodes alone and its co-existing system with electrolyte.

  3. 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.

  4. Physico-Geometrical Kinetics of Solid-State Reactions in an Undergraduate Thermal Analysis Laboratory

    Science.gov (United States)

    Koga, Nobuyoshi; Goshi, Yuri; Yoshikawa, Masahiro; Tatsuoka, Tomoyuki

    2014-01-01

    An undergraduate kinetic experiment of the thermal decomposition of solids by microscopic observation and thermal analysis was developed by investigating a suitable reaction, applicable techniques of thermal analysis and microscopic observation, and a reliable kinetic calculation method. The thermal decomposition of sodium hydrogen carbonate is…

  5. SIMULATION OF THERMAL DECOMPOSITION OF MINERAL INSULATING OIL

    Directory of Open Access Journals (Sweden)

    V. G. M. Cruz

    2015-09-01

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

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

    African Journals Online (AJOL)

    NJD

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

  7. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  8. Hydrogen peroxide decomposition kinetics in aquaculture water

    DEFF Research Database (Denmark)

    Arvin, Erik; Pedersen, Lars-Flemming

    2015-01-01

    Hydrogen peroxide (HP) is used in aquaculture systems where preventive or curative water treatments occasionally are required. Use of chemical agents can be challenging in recirculating aquaculture systems (RAS) due to extended water retention time and because the agents must not damage the fish ...... in RAS by addressing disinfection demand and identify efficient and safe water treatment routines.......Hydrogen peroxide (HP) is used in aquaculture systems where preventive or curative water treatments occasionally are required. Use of chemical agents can be challenging in recirculating aquaculture systems (RAS) due to extended water retention time and because the agents must not damage the fish...... reared or the nitrifying bacteria in the biofilters at concentrations required to eliminating pathogens. This calls for quantitative insight into the fate of the disinfectant residuals during water treatment. This paper presents a kinetic model that describes the HP decomposition in aquaculture water...

  9. Kinetics of bromochloramine formation and decomposition.

    Science.gov (United States)

    Luh, Jeanne; Mariñas, Benito J

    2014-01-01

    Batch experiments were performed to study the kinetics of bromochloramine formation and decomposition from the reaction of monochloramine and bromide ion. The effects of pH, initial monochloramine and bromide ion concentrations, phosphate buffer concentration, and excess ammonia were evaluated. Results showed that the monochloramine decay rate increased with decreasing pH and increasing bromide ion concentration, and the concentration of bromochloramine increased to a maximum before decreasing gradually. The maximum bromochloramine concentration reached was found to decrease with increasing phosphate and ammonia concentrations. Previous models in the literature were not able to capture the decay of bromochloramine, and therefore we proposed an extended model consisting of reactions for monochloramine autodecomposition, the decay of bromamines in the presence of bromide, bromochloramine formation, and bromochloramine decomposition. Reaction rate constants were obtained through least-squares fitting to 11 data sets representing the effect of pH, bromide, monochloramine, phosphate, and excess ammonia. The reaction rate constants were then used to predict monochloramine and bromochloramine concentration profiles for all experimental conditions tested. In general, the modeled lines were found to provide good agreement with the experimental data under most conditions tested, with deviations occurring at low pH and high bromide concentrations.

  10. Kinetics of non-isothermal decomposition of cinnamic acid

    Science.gov (United States)

    Zhao, Ming-rui; Qi, Zhen-li; Chen, Fei-xiong; Yue, Xia-xin

    2014-07-01

    The thermal stability and kinetics of decomposition of cinnamic acid were investigated by thermogravimetry and differential scanning calorimetry at four heating rates. The activation energies of this process were calculated from analysis of TG curves by methods of Flynn-Wall-Ozawa, Doyle, Distributed Activation Energy Model, Šatava-Šesták and Kissinger, respectively. There are only one stage of thermal decomposition process in TG and two endothermic peaks in DSC. For this decomposition process of cinnamic acid, E and log A[s-1] were determined to be 81.74 kJ mol-1 and 8.67, respectively. The mechanism was Mampel Power law (the reaction order, n = 1), with integral form G(α) = α (α = 0.1-0.9). Moreover, thermodynamic properties of Δ H ≠, Δ S ≠, Δ G ≠ were 77.96 kJ mol-1, -90.71 J mol-1 K-1, 119.41 kJ mol-1.

  11. 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

  12. Pressure Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E A; Zaug, J M; Burnham, A K

    2009-05-29

    The effect of pressure on the thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low to moderate pressures (i.e. between ambient pressure and 1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure enhanced autocatalysis whereas the deceleration at high pressures is attributed pressure inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both {beta} and {delta} phase HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  13. Evaluation of kinetic parameters of thermal and oxidative decomposition of base oils by conventional, isothermal and modulated TGA, and pressure DSC

    Energy Technology Data Exchange (ETDEWEB)

    Gamlin, C.D.; Dutta, N.K.; Roy Choudhury, N.; Matisons, J. [Ian Wark Research Institute, University of South Australia, SA 5095 Mawson Lakes (Australia); Kehoe, D. [Castrol Australia Pty. Ltd., NSW 2161 Guildford (Australia)

    2002-09-15

    Multigrade engine oils used in today's sophisticated engines are carefully engineered products. Different ingredients, such as viscosity index improvers, dispersants, antioxidants, detergents, antiwear agents, pour point depressants, etc. are added to the base oils to improve their performance as lubricants, significantly. However, the ultimate performance of the lubricant principally depends on the quality of the base oil. Therefore, understanding the degradation behaviour of the base oil is of significant importance. In this study, the kinetic parameters of the decomposition of different types and grades of base oils (all-natural, fully synthetic and semi-synthetic) have been investigated in detail by conventional and isothermal thermogravimetric analyses (TGA) as well as modulated TGA (MTGA{sup registered}). Pressure DSC (PDSC) has been employed to evaluate the spontaneous ignition and oxidative degradation behaviour of the base oils. Base oils with higher viscosity within the same grade tend to degrade at higher temperatures. It appears that the degradation of the oils studied can be modelled by an nth-order mechanism and have similar activation energies of degradation under an inert atmosphere. The all-natural base oil ALOR100 is more resistant to oxidation than the semi-synthetic Yubase4 and fully synthetic PAO4 due to the presence of naturally occurring antioxidants.

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

    African Journals Online (AJOL)

    denise

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

  15. Thermal decomposition of lead titanyl oxalate tetrahydrate

    NARCIS (Netherlands)

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

    1976-01-01

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

  16. Thermal decomposition of dolomite under CO2-air atmosphere

    Science.gov (United States)

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

    2017-01-01

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

  17. Application of Non-Isothermal Thermogravimetric Method to Interpret the Decomposition Kinetics of , and

    Science.gov (United States)

    Pouretedal, H. R.; Ebadpour, R.

    2014-05-01

    The non-isothermal thermogravimetric method was used to study the thermal decomposition of , and at heating rates of (5, 10, 15, and 20) . The activation energy of thermal decomposition reactions was computed by isoconversional methods of Ozawa-Flynn-Wall, Kissinger-Akahiro-Sunose, and Friedman equations. Also, the kinetic triplet of the thermal decomposition of salts was determined by the model-fitting method of the modified Coats-Redfern equation. The activation energies of , and of (293 to 307, 160 to 209, and 192 to 245) , respectively, are obtained by non-isothermal isoconversional methods. The modified Coats and Redfern method showed that the most probable mechanism functions of (model A3: Arami-Erofeev equation) and (model F2: second order) can be used to predict the decomposition mechanisms of , , and , respectively.

  18. Thermal kinetic inductance detector

    Science.gov (United States)

    Cecil, Thomas; Gades, Lisa; Miceli, Antonio; Quaranta, Orlando

    2016-12-20

    A microcalorimeter for radiation detection that uses superconducting kinetic inductance resonators as the thermometers. The detector is frequency-multiplexed which enables detector systems with a large number of pixels.

  19. 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.

  20. Thermal decompositions of light lanthanide aconitates

    Energy Technology Data Exchange (ETDEWEB)

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

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-01

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

  2. KINETICS OF HYDROXIDE PHOMOTED DECOMPOSITION 0F ...

    African Journals Online (AJOL)

    1991-04-26

    (Received July 2?. 1990; revised April 26, 1991). ABSTRACT. The effects of varying concentrations of dimethyl sulphoxide in mixture with water on rates and activation parameters for the hydroxide promoted decomposition of tetraphenylphosphonium chloride have been studied. Increasing the DMSO content of the reaction ...

  3. Thermal decomposition as route for silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Navaladian S

    2006-01-01

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

  4. Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition

    Directory of Open Access Journals (Sweden)

    LJILJANA KOLAR-ANIC

    2000-10-01

    Full Text Available The kinetics of the Belousov-Zhabotinsky (BZ oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant, k = 7.5×10-3 min-1, was found.

  5. Thermal Decomposition Chemistry of Amine Borane (U)

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-29

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

  6. Oxidative synthesis of a novel polyphenol having pendant Schiff base group: Synthesis, characterization, non-isothermal decomposition kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Dilek, Deniz [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Dogan, Fatih, E-mail: fatihdogan@comu.edu.tr [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Bilici, Ali, E-mail: alibilici66@hotmail.com [Control Laboratory of Agricultural and Forestry Ministry, 34153 Istanbul (Turkey); Kaya, Ismet [Department of Chemistry, Faculty of Science and Arts, Canakkale Onsekiz Mart University, Canakkale (Turkey)

    2011-05-10

    Research highlights: {yields} In this study, the synthesis and thermal characterization of a new functional polyphenol are reported. {yields} Non-isothermal methods were used to evaluate the thermal decomposition kinetics of resulting polymer. {yields} Thermal decomposition of polymer follows a diffusion type kinetic model. {yields} It is noted that this kinetic model is quite rare in polymer degradation studies. - Abstract: In here, the facile synthesis and thermal characterization of a novel polyphenol containing Schiff base pendant group, poly(4-{l_brace}[(4-hydroxyphenyl)imino]methyl{r_brace}benzene-1,2,3-triol) [PHPIMB], are reported. UV-vis, FT-IR, {sup 1}H NMR, {sup 13}C NMR, GPC, TG/DTG-DTA, CV (cyclic voltammetry) and solid state conductivity measurements were utilized to characterize the obtained monomer and polymer. The spectral analyses results showed that PHPIMB was composed of polyphenol main chains containing Schiff base pendant side groups. Thermal properties of the polymer were investigated by thermogravimetric analyses under a nitrogen atmosphere. Five methods were used to study the thermal decomposition of PHPIMB at different heating rate and the results obtained by using all the kinetic methods were compared with each other. The thermal decomposition of PHPIMB was found to be a simple process composed of three stages. These investigated methods were those of Flynn-Wall-Ozawa (FWO), Tang, Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods.

  7. Thermal decompositions of heavy lanthanide aconitates

    Energy Technology Data Exchange (ETDEWEB)

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

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

  8. Thermal Decomposition of Radiation-Damaged Polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    J Abrefah GS Klinger

    2000-09-26

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

  9. Thermal Decomposition of Radiation-Damaged Polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Abrefah, John; Klinger, George S.

    2000-09-26

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

  10. Pressure-Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

    Science.gov (United States)

    Glascoe, Elizabeth A.; Zaug, Joseph M.; Burnham, Alan K.

    2009-10-01

    The effect of pressure on the global thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Global decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low-to-moderate pressures (i.e., between ambient pressure and 0.1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure-enhanced autocatalysis, whereas the deceleration at high pressures is attributed to pressure-inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both the β- and δ-polymorphs of HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  11. Pressure-dependent decomposition kinetics of the energetic material HMX up to 3.6 GPa.

    Science.gov (United States)

    Glascoe, Elizabeth A; Zaug, Joseph M; Burnham, Alan K

    2009-12-03

    The effect of pressure on the global thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Global decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low-to-moderate pressures (i.e., between ambient pressure and 0.1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure-enhanced autocatalysis, whereas the deceleration at high pressures is attributed to pressure-inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both the beta- and delta-polymorphs of HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  12. Atmospheric chemistry of CF3C(O)O2 radicals. Kinetics of their reaction with NO2 and kinetics of the thermal decomposition of the product CF3C(O)O2NO2

    DEFF Research Database (Denmark)

    Wallington, T.J.; Sehested, J.; Nielsen, O.J.

    1994-01-01

    decomposition CF3C(O)O2NO2. The rate of decomposition of CF3C(O)O2NO2 was independent of the total pressure of N2 diluent over the range 100-700 Torr and was fit by the expression k-1 = (1.9(-1.5)+7.6) x 10(16) exp[(-14000 +/- 480)/T] s-1. Implications for the atmospheric chemistry of CFC replacements...

  13. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

  15. 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.

  16. Thermal-decomposition studies of HMX

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-10-20

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

  17. Thermochemistry and kinetics of graphite oxide exothermic decomposition for safety in large-scale storage and processing.

    Science.gov (United States)

    Qiu, Yang; Collin, Felten; Hurt, Robert H; Külaots, Indrek

    2016-01-01

    The success of graphene technologies will require the development of safe and cost-effective nano-manufacturing methods. Special safety issues arise for manufacturing routes based on graphite oxide (GO) as an intermediate due to its energetic behavior. This article presents a detailed thermochemical and kinetic study of GO exothermic decomposition designed to identify the conditions and material compositions that avoid explosive events during storage and processing at large scale. It is shown that GO becomes more reactive for thermal decomposition when it is pretreated with OH(-) in suspension and the effect is reversible by back-titration to low pH. This OH(-) effect can lower the decomposition reaction exotherm onset temperature by up to 50 degrees of Celsius, causing overlap with common drying operations (100-120°C) and possible self-heating and thermal runaway during processing. Spectroscopic and modeling evidence suggest epoxide groups are primarily responsible for the energetic behavior, and epoxy ring opening/closing reactions are offered as an explanation for the reversible effects of pH on decomposition kinetics and enthalpies. A quantitative kinetic model is developed for GO thermal decomposition and used in a series of case studies to predict the storage conditions under which spontaneous self-heating, thermal runaway, and explosions can be avoided.

  18. Thermal physics kinetic theory and thermodynamics

    CERN Document Server

    Singh, Devraj; Yadav, Raja Ram

    2016-01-01

    THERMAL PHYSICS: Kinetic Theory and Thermodynamics is designed for undergraduate course in Thermal Physics and Thermodynamics. The book provides thorough understanding of the fundamental principles of the concepts in Thermal Physics. The book begins with kinetic theory, then moves on liquefaction, transport phenomena, the zeroth, first, second and third laws, thermodynamics relations and thermal conduction. The book concluded with radiation phenomenon. KEY FEATURES: * Include exercises * Short Answer Type Questions * Long Answer Type Questions * Numerical Problems * Multiple Choice Questions

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

    Indian Academy of Sciences (India)

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

  20. 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...

  1. 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 ...

  2. Thermal dehydration kinetics of phosphogypsum

    Directory of Open Access Journals (Sweden)

    López, F. A.

    2015-09-01

    Full Text Available Phsophogypsum is a by-product from the processing phosphate rock. Before the use of it in cement industry such as setting regulator is necessary a study of dehydration reaction of phosphogypsum to avoid the false setting during the milling. The aim is to study the thermal behavior of two different phosphogypsum sources (Spain and Tunisia under non-isothermal conditions in argon atmosphere by using Thermo-Gravimetriy, Differential Thermal Analysis (TG-DTA and Differential Scanning Calorimetry (DSC. DSC experiments were carried out at temperatures ranging from ambient to 350 °C at different heating rates. The temperatures of conversion from gypsum to hemihydrate and anhydrite states and heat of dehydration were determined. Various methods were used to analyze the DSC data for reaction kinetics determination. The activation energy and frequency factor were calculated for dehydration of phosphogypsum. Activation energy values of the main dehydration reaction of phosphogypsum were calculated to be approximately 61–118 kJ/mol.El fosfoyeso es un subproducto procedente del procesado de la roca fosfato. Una de las posibles vías de reutilización y revalorización es su uso como regulador del fraguado en la industria cementera. Debido a los posibles problemas de falso fraguado asociado a los procesos de deshidratación que tienen lugar durante la molienda del cemento, esta investigación estudió el comportamiento térmico, bajo condiciones no-isotérmicas en atmósfera de argón, de dos fosfoyesos, mediante TG-DTA y DSC. Los ensayos de DSC se realizaron hasta los 350 °C a diferentes velocidades de calentamiento. La temperatura de conversión del yeso a las formas de hemihidrato y anhidrita y el calor de hidratación fueron determinados. Las cinéticas de reacción fueron obtenidas analizando los datos de DSC mediante varios métodos. Se calculó la energía de activación y el factor de frecuencia para las reacciones de deshidratación del

  3. The Products of the Thermal Decomposition of CH3CHO

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-06

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

  4. Comparative decomposition kinetics of neutral monosaccharides by microwave and induction heating treatments.

    Science.gov (United States)

    Tsubaki, Shuntaro; Oono, Kiriyo; Onda, Ayumu; Yanagisawa, Kazumichi; Azuma, Jun-ichi

    2013-06-28

    The stabilities of five neutral monosaccharides (glucose, galactose, mannose, arabinose, and xylose) were kinetically compared after the molecules were submitted to microwave heating (internal heating) and induction heating (external heating) under completely identical thermal histories by employing PID (proportional, integral, and derivative) temperature controlled ovens and homogeneous mixing. By heating in water at 200°C, the rate constants for the decomposition reactions varied from 2.13×10(-4) to 3.87×10(-4)s(-1) for microwave heating; however, the values increased by 1.1- to 1.5-fold for induction heating. Similarly, in a dilute (0.8%) sulfuric acid solution, the decomposition rate constants varied from 0.61×10(-3) to 2.00×10(-3)s(-1) for microwave heating; however, the values increased by 1.5- to 2.2-fold for induction heating. The results show that microwave heating imparts greater stability to neutral monosaccharides than does induction heating. The undesirable decomposition of monosaccharides at the surface boundary of reactor walls may have increased the probability of monosaccharide decomposition during induction heating. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Thermal degradation kinetics and solid state, temperature ...

    Indian Academy of Sciences (India)

    WINTEC

    Phenothiazine derivatives belong to a big group of aromatic compounds. These derivatives are substituted in ... Elemental analysis for carbon, hydrogen, nitrogen and sulphur were done using Vario EL III CHNS ... The aim of the kinetic study of thermal analysis data is to find out the most probable kinetic model which best ...

  6. Isothermal decomposition kinetics of nickel (II) hydroxide powder

    Energy Technology Data Exchange (ETDEWEB)

    Carney, C.S., E-mail: Casey.Carney@CONTR.NETL.DOE.GOV [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States); Chinn, R.E.; Doğan, Ö.N. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); Gao, M.C. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States)

    2015-09-25

    Highlights: • A first order random nucleation model was proposed for the decomposition of nickel hydroxide. • Trapped lattice product water greatly suppressed high conversion reaction rates. • Annealing experiments of the Ni–Ni(OH){sub 2}–NiO phase triangle yielded only two phases: Ni and NiO. • This Ni–Ni(OH){sub 2}–NiO phase triangle in the Ni-rich corner of the Ni–O–H system was confirmed. - Abstract: Nickel (II) hydroxide powder was investigated by thermogravimetry for isothermal decomposition kinetics and verification of the Ni–O–H ternary phase diagram at low temperatures. The activation energy and frequency factor were measured as E{sub a} = 134 kJ/mol and A = 1.27 × 10{sup 10} s{sup −1}, respectively. The validity of the first-order random nucleation model was confirmed, as opposed to diffusion and or moving-boundary models. The dependence of TGA results on specimen size was noted. The Ni–Ni(OH){sub 2}–NiO phase triangle was confirmed. Accordingly, a thermodynamic description of the system was established in the Ni-rich corner, and the isotherm at room temperature is calculated.

  7. The coke drum thermal kinetic effects

    Energy Technology Data Exchange (ETDEWEB)

    Aldescu, Maria M.; Romero, Sim; Larson, Mel [KBC Advanced Technologies plc, Surrey (United Kingdom)

    2012-07-01

    The coke drum thermal kinetic dynamics fundamentally affect the coker unit yields as well as the coke product properties and unit reliability. In the drum the thermal cracking and polymerization or condensation reactions take place in a semi-batch environment. Understanding the fundamentals of the foaming kinetics that occur in the coke drums is key to avoiding a foam-over that could result in a unit shutdown for several months. Although the most dynamic changes with time occur during drum filling, other dynamics of the coker process will be discussed as well. KBC has contributed towards uncovering and modelling the complexities of heavy oil thermal dynamics. (author)

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

    Indian Academy of Sciences (India)

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

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

    Indian Academy of Sciences (India)

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

  10. alumina phase transformation from thermal decomposition

    African Journals Online (AJOL)

    HOD

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-15

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

  12. The products of the thermal decomposition of CH3CHO.

    Science.gov (United States)

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

    2011-07-07

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

  13. Thermal dehydration kinetics of phosphogypsum

    OpenAIRE

    López, F. A.; Tayibi, H.; García-Díaz, I.; Alguacil, F. J.

    2015-01-01

    Phsophogypsum is a by-product from the processing phosphate rock. Before the use of it in cement industry such as setting regulator is necessary a study of dehydration reaction of phosphogypsum to avoid the false setting during the milling. The aim is to study the thermal behavior of two different phosphogypsum sources (Spain and Tunisia) under non-isothermal conditions in argon atmosphere by using Thermo-Gravimetriy, Differential Thermal Analysis (TG-DTA) and Differential Scanning Calori...

  14. Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Vetter, Tiffany A.; Colombo, D. Philip, Jr.

    2003-07-01

    CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

  15. Isoconversional kinetics of thermally stimulated processes

    CERN Document Server

    Vyazovkin, Sergey

    2015-01-01

    The use of isoconversional kinetic methods for analysis of thermogravimetric and calorimetric data on thermally stimulated processes is quickly growing in popularity. The purpose of this book is to create the first comprehensive resource on the theory and applications of isoconversional methodology. The book introduces the reader to the kinetics of physical and chemical condensed phase processes that occur as a result of changing temperature and discusses how isoconversional analysis can provide important kinetic insights into them. The book will help the readers to develop a better understanding of the methodology, and promote its efficient usage and successful development.

  16. Mechanism of the Thermal Decomposition of Ethanethiol and Dimethylsulfide

    Science.gov (United States)

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

    2016-06-01

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

  17. Computational study on decomposition kinetics of CH3CFClO radical

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 5. Computational study on decomposition kinetics of CH3CFClO radical ... The present study deals with the decomposition of haloalkoxy radical (CH3CFClO) formed from 1,1-dichloro-1-fluoroethane (HCFC-141b) in the atmosphere. The sudy is performed ...

  18. 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.)

  19. Programming Enhancements for Low Temperature Thermal Decomposition Workstation

    Energy Technology Data Exchange (ETDEWEB)

    Igou, R.E.

    1998-10-01

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

  20. Thermal Plasma Decomposition Of Nickel And Cobalt Compounds

    Directory of Open Access Journals (Sweden)

    Woch M.

    2015-06-01

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

  1. Kinetics of spinodal decomposition in driven nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Razumov, I.K. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation)]. E-mail: rik@imp.uran.ru; Gornostyrev, Yu. N. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation); Yermakov, A. Ye. [Institute of Metal Physics, Ural Branch of RAS, 18 Kovalevskaya Street, Ekaterinburg 620041 (Russian Federation)

    2007-05-31

    The effect of grain boundaries (GB) on decomposition of solid solution was investigated in the framework generalized lattice gas model taking into account both local variation of chemical potential and the diffusion mobility near GB. It was shown that nonequilibrium GB can essentially change the phase equilibrium of alloy and surface directed spinodal decomposition (SDSD) caused by GB determines the precipitation morphology in nanograined materials. The increase of atomic mobility near GB can result in formation of lamellar structure propagating from GB to inside the grains and variation in morphology from lamellar to drop-like type structure when composition change.

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

    Directory of Open Access Journals (Sweden)

    Miao Yao

    2013-01-01

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

  3. The influence of temperature on the decomposition kinetics of peracetic acid in solutions

    Directory of Open Access Journals (Sweden)

    Kunigk L.

    2001-01-01

    Full Text Available Peracetic acid is a powerful sanitizer that has only recently been introduced in the Brazilian food industry. The main disadvantage of this sanitizer is its decomposition rate. The main purpose of this paper is to present results obtained in experiments carried out to study the decomposition kinetics of peracetic acid in aqueous solutions at 25, 35, 40 and 45 °C. The decompositon of peracetic acid is a first-order reaction. The decomposition rate constants are between 1.71x10-3 h -1 for 25 °C and 9.64x10-3 h-1 for 45 °C. The decomposition rate constant is affected by temperature according to the Arrhenius equation, and the activation energy for the decomposition of peracetic acid in aqueous solutions prepared from the commercial formulation used in this work is 66.20 kJ/mol.

  4. Isothermal decomposition kinetics in the Cu-9%Al-4%Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.T.; Silva, R.A.G

    2004-07-28

    The influence of 4 wt.%Ag addition on the isothermal decomposition kinetics of the {beta}' phase in the Cu-9 wt.%Al alloy was studied by microhardness measurements, optical and scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and X-ray diffractometry. The results showed that the presence of Ag decreases the {beta}'{yields}({alpha}+{gamma}{sub 1}) decomposition reaction rate in the Cu-9%Al-4%Ag alloy, an effect that may be associated to the {gamma}{sub 1} phase which catalyses the Ag precipitation, making it faster than the decomposition reaction, and thus, stabilizing the martensitic phase.

  5. 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.

  6. KINETIC ANALYSIS OF THE CATALYTIC DECOMPOSITION OF HYDRAZINE

    Directory of Open Access Journals (Sweden)

    J.E. de MEDEIROS

    1998-06-01

    Full Text Available The bond-order conservation method was used to study the catalytic decomposition of N2H4. Variation in the activation energy, E, of the most relevant steps was calculated as a function of the enthalpy of adsorption of N, QN, between 0 and 1250 kJmol-1. Results suggest that below QN = 520 kJmol-1 the catalytic decomposition of N2H4 produces mostly N2 and H2. Above QN = 520 kJmol-1, NH3 and N2 are the main products. Near QN = 520 kJmol-1 N2, H2 and NH3 are obtained, in agreement with experimental results on different metals.

  7. Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

    Directory of Open Access Journals (Sweden)

    Hongbo Y.

    2015-06-01

    Full Text Available The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

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

    Science.gov (United States)

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

    2009-09-01

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

  9. 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.

  10. Influence of vermicomposting on solid wastes decomposition kinetics in soils*

    Science.gov (United States)

    Nourbakhsh, Farshid

    2007-01-01

    The effect of vermicomposting on kinetic behavior of the products is not well recognized. An incubation study was conducted to investigate C mineralization kinetics of cow manure, sugarcane filter cake and their vermicomposts. Two different soils were treated with the four solid wastes at a rate of 0.5 g solid waste C per kg soil with three replications. Soils were incubated for 56 d. The CO2-C respired was monitored periodically and a first-order kinetic model was used to calculate the kinetic parameters of C mineralization. Results indicated that the percentage of C mineralized during the incubation period ranged from 31.9% to 41.8% and 55.9% to 73.4% in the calcareous and acidic soils, respectively. The potentially mineralizable C (C 0) of the treated soils was lower in the solid waste composts compared to their starting materials. Overall, it can be concluded that decomposable fraction of solid wastes has decreased due to vermicomposting. PMID:17910115

  11. 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.

  12. 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.

  13. Thermal Decomposition Study on CuInSe2 Single Crystals

    Science.gov (United States)

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

    2018-01-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  15. Study on the decomposition kinetics of FOX-7 and HNF

    NARCIS (Netherlands)

    Klerk, W.P.C. de; Popescu, C.; Heijden, A.E.D.M. van der

    2003-01-01

    At TNO Prins Maurits Laboratory the characterisation and application of energetic materials is one of the main research topics. In this respect, the activities are focussed on using thermal analysis techniques such as TG/DTA and DSC. Standard DSC and TG/DTA techniques usually apply a linear

  16. Effects of compositional changes on reactivity continuum and decomposition kinetics of lake dissolved organic matter

    Science.gov (United States)

    Mostovaya, Alina; Koehler, Birgit; Guillemette, François; Brunberg, Anna-Kristina; Tranvik, Lars J.

    2016-07-01

    To address the link between the composition and decomposition of freshwater dissolved organic matter (DOM), we manipulated the DOM from three boreal lakes using preincubations with UV light to cleave large aromatic molecules and polyvinylpyrrolidone (PVP) to remove colored phenolic compounds. Subsequently, we monitored the dissolved organic carbon (DOC) loss over 4 months of microbial degradation in the dark to assess how compositional changes in DOM affected different aspects of the reactivity continuum, including the distribution of the apparent decay coefficients. We observed profound effects on decomposition kinetics, with pronounced shifts in the relative share of rapidly and more slowly decomposing fractions of the DOM. In the UV-exposed treatment initial apparent decay coefficient k0 was almost threefold higher than in the control. Significantly higher relative DOC loss in the UV-exposed treatment was sustained for 2 months of incubation, after which decay coefficients converged with those in the control. The PVP removed compounds with absorbance and fluorescence characteristics representative of aromatic compounds, which led to slower decomposition, compared to that in the control. Our results demonstrate the reactivity continuum underlying the decomposition of DOM in freshwaters and highlight the importance of intrinsic properties of DOM in determining its decomposition kinetics.

  17. Benzoxyl radical decomposition kinetics: formation of benzaldehyde + H, phenyl + CH2O, and benzene + HCO.

    Science.gov (United States)

    da Silva, Gabriel; Bozzelli, Joseph W

    2009-06-25

    The kinetics of benzoxyl radical decomposition was studied using ab initio computational chemistry and RRKM rate theory. The benzoxyl radical is an important but short-lived intermediate in the combustion of toluene and other alkylated aromatic hydrocarbons. A theoretical study of the thermochemistry and kinetics to products over a range of temperatures and pressures for benzoxyl decomposition is reported. Ab initio calculations with the G3X theoretical method reveal low-energy pathways from the benzoxyl radical to benzaldehyde + H and the phenyl radical + formaldehyde (CH(2)O), as well as a novel mechanism to benzene + the formyl radical (HC(*)O). RRKM simulations were performed for benzoxyl decomposition as a function of temperature and pressure. Benzaldehyde formation constitutes more than 80% of the total reaction products at temperatures below 1000 K, decreasing to around 50% at 2000 K. Formation of benzene + HC(*)O and phenyl + CH(2)O is of similar importance, each accounting for 5-10% of the decomposition products at around 1000 K, increasing to 20-30% at 2000 K. The results presented here should lead to improved kinetic models for the oxidation of alkylated aromatic hydrocarbons, particularly for the formation of benzene as a direct oxidation product of toluene. Re-evaluation of the phenyl radical heat of formation leads us to suggest a benzene C-H bond dissociation energy in the range of 113.5-114.5 kcal mol(-1).

  18. Non-isothermal kinetics of thermal degradation of chitosan

    Directory of Open Access Journals (Sweden)

    Georgieva Velyana

    2012-08-01

    Full Text Available Abstract Background Chitosan is the second most abundant nitrogen containing biopolymer in nature, obtained from the shells of crustaceans, particularly crabs, shrimp and lobsters, which are waste products of seafood processing industries. It has great potential application in the areas of biotechnology, biomedicine, food industries, and cosmetics. Chitosan is also capable of adsorbing a number of metal ions as its amino groups can serve as chelation sites. Grafted functional groups such as hydroxyl, carboxyl, sulfate, phosphate, and amino groups on the chitosan have been reported to be responsible for metal binding and sorption of dyes and pigments. The knowledge of their thermal stability and pyrolysis may help to better understand and plan their industrial processing. Results Thermogravimetric studies of chitosan in air atmosphere were carried out at six rates of linear increasing of the temperature. The kinetics and mechanism of the thermal decomposition reaction were evaluated from the TG data using recommended from ICTAC kinetics committee iso-conversional calculation procedure of Kissinger-Akahira-Sunose, as well as 27 mechanism functions. The comparison of the obtained results showed that they strongly depend on the selection of proper mechanism function for the process. Therefore, it is very important to determine the most probable mechanism function. In this respect the iso-conversional calculation procedure turned out to be the most appropriate. Conclusion Chitosan have excellent properties such as hydrophilicity, biocompatibility, biodegradability, antibacterial, non-toxicity, adsorption application. The thermal degradation of chitosan occurs in two stages. The most probable mechanism function for both stages is determined and it was best described by kinetic equations of n-th order (Fn mechanism. For the first stage, it was established that n is equal to 3.0 and for the second stage – to 1.0 respectively. The values of the

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

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.; Bulusu, S.

    1993-02-01

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

  20. Non-isothermal decomposition kinetics of magnesite Decomposição não isotérmica de magnesita

    Directory of Open Access Journals (Sweden)

    S. Maitra

    2007-09-01

    Full Text Available Kinetics of thermal decomposition of Indian magnesite was studied by thermo-gravimetric analysis under non-isothermal condition. Coats and Redfern Integral approximation method was used to determine the kinetic parameters. Using the kinetic parameters different kinetic functions were analyzed with the experimental data to ascertain the decomposition mechanism of magnesium carbonate and it was observed that the decomposition reaction followed a contracting sphere kinetic mechanism.A cinética de decomposição térmica de magnesita indiana foi estudada por análise termogravimétrica sob condição não-isotérmica. O método da aproximação da integral de Coats e Redfern foi usado para determinar os parâmetros cinéticos. Usando estes parâmetros, foram analisadas diferentes funções cinéticas com os dados experimentais para avaliar o mecanismo de decomposição do carbonato de magnésio e foi observado que a reação de decomposição segue o mecanismo cinético de contração de esfera.

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

    Science.gov (United States)

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

    1985-09-01

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

  2. 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.

  3. Characterization, non-isothermal decomposition kinetics and photocatalytic water splitting of green chemically synthesized polyoxoanions of molybdenum containing phosphorus as hetero atom

    Energy Technology Data Exchange (ETDEWEB)

    D’Cruz, Bessy [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); Samuel, Jadu, E-mail: jadu_samuel@yahoo.co.in [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); George, Leena [Catalysis and Inorganic Chemistry Division, National Chemical Laboratory, Pune 411008 (India)

    2014-11-20

    Highlights: • CPM nanorods were synthesized by applying the principles of green chemistry. • The isoconversional method was used to analyze the effective activation energy. • The appropriate reaction models of the two decomposition stages were determined. • Photocatalytic water splitting was investigated in the presence of platinum co-catalyst. - Abstract: In here, the green synthesis and thermal characterization of a novel polyoxoanions of molybdenum containing phosphorus as hetero atom are reported. The composition and morphology of the nanorods were established by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopic (ICP-AES) techniques. Thermal properties of the nanoparticles were investigated by non-isothermal analysis under nitrogen atmosphere. The values activation energy of each stage of thermal decomposition for all heating rates was calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunnose (KAS) methods. Invariant kinetic parameter (IKP) method and master plot method were also used to evaluate the kinetic parameters and mechanism for the thermal decomposition of cetylpyridinium phosphomolybdate (CPM). Photocatalytic water oxidation mechanism using CPM catalyst in the presence of platinum (Pt) co-catalyst enhances the H{sub 2} evolution and was found to be 1.514 mmol/g/h.

  4. A study on the kinetics of ozone decomposition in waters of different quality

    Directory of Open Access Journals (Sweden)

    Takić Ljiljana M.

    2004-01-01

    Full Text Available The kinetics of ozone decomposition in waters of different quality, namely distilled water, tap water previously treated with ozone, tap water not treated with ozone and raw water from an accumulation lake, were studied in a batch stirred reactor at different temperatures (18-28°C. The dissolved ozone concentration was measured by the iodometric titration method. It was determined that an empirical kinetic equation of the form: dc(O3/dt= k0 + k1c(O3 fitted the experimental data better than a first-order reaction rate equation. The apparent reaction rate constants in the case of ozone decomposition in distilled water were shown to be a function of temperature in accordance with the Arrhenius equation.

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

    Science.gov (United States)

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

    2015-11-28

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

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

    National Research Council Canada - National Science Library

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

    2016-01-01

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

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

    OpenAIRE

    A. Dinesh Karthik; Dr. K. Geetha

    2017-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-09-15

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

  9. 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.

  10. Thermal Decomposition of RDX from Reactive Molecular Dynamics

    National Research Council Canada - National Science Library

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

    2005-01-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

  12. Kinetics of methane hydrate decomposition studied via in situ low temperature X-ray powder diffraction.

    Science.gov (United States)

    Everett, S Michelle; Rawn, Claudia J; Keffer, David J; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy J

    2013-05-02

    Gas hydrate is known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Based on results from the decomposition of three nominally similar methane hydrate samples, the kinetics of two regions, 180-200 and 230-260 K, within the overall decomposition range 140-260 K, were studied by in situ low temperature X-ray powder diffraction. The kinetic rate constants, k(a), and the reaction mechanisms, n, for ice formation from methane hydrate were determined by the Avrami model within each region, and activation energies, E(a), were determined by the Arrhenius plot. E(a) determined from the data for 180-200 K was 42 kJ/mol and for 230-260 K was 22 kJ/mol. The higher E(a) in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  13. Hydrothermal decomposition of industrial jarosite in alkaline media: The rate determining step of the process kinetics

    Directory of Open Access Journals (Sweden)

    González-Ibarra A.A.

    2016-01-01

    Full Text Available This work examines the role of NaOH and Ca(OH2 on the hydrothermal decomposition of industrial jarosite deposited by a Mexican company in a tailings dam. The industrial jarosite is mainly composed by natrojarosite and contains 150 g Ag/t, showing a narrow particle size distribution, as revealed by XRD, fire assay, SEM-EDS and laser-diffraction analysis. The effect of the pH, when using NaOH or Ca(OH2 as alkalinizing agent was studied by carrying out decomposition experiments at different pH values and 60°C in a homogeneous size particle system (pH = 8, 9, 10 and 11 and in a heterogeneous size particle system (pH = 11. Also, the kinetic study of the process and the controlling step of the decomposition reaction when NaOH and Ca(OH2 are used was determined by fitting the data obtained to the shrinking core model for spherical particles of constant size. These results, supported by chemical (EDS, morphological (SEM and mapping of elements (EDS analysis of a partially reacted jarosite particle allowed to conclude that when NaOH is used, the process kinetics is controlled by the chemical reaction and when Ca(OH2 is used, the rate determining step is changed to a diffusion control through a layer of solid products.

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

    Science.gov (United States)

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

    2015-07-07

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

  15. Kinetics of gas phase formic acid decomposition on platinum single crystal and polycrystalline surfaces

    Science.gov (United States)

    Detwiler, Michael D.; Milligan, Cory A.; Zemlyanov, Dmitry Y.; Delgass, W. Nicholas; Ribeiro, Fabio H.

    2016-06-01

    Formic acid dehydrogenation turnover rates (TORs) were measured on Pt(111), Pt(100), and polycrystalline Pt foil surfaces at a total pressure of 800 Torr between 413 and 513 K in a batch reactor connected to an ultra-high vacuum (UHV) system. The TORs, apparent activation energies, and reaction orders are not sensitive to the structure of the Pt surface, within the precision of the measurements. CO introduced into the batch reactor depressed the formic acid dehydrogenation TOR and increased the reaction's apparent activation energies on Pt(111) and Pt(100), consistent with behavior predicted by the Temkin equation. Two reaction mechanisms were explored which explain the formic acid decomposition mechanism on Pt, both of which include dissociative adsorption of formic acid, rate limiting formate decomposition, and quasi-equilibrated hydrogen recombination and CO adsorption. No evidence was found that catalytic supports used in previous studies altered the reaction kinetics or mechanism.

  16. 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.

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Proper Orthogonal Decomposition analysis of kinetic energy entrainment in large wind farms

    Science.gov (United States)

    Verhulst, Claire; Meneveau, Charles

    2012-11-01

    Vertical entrainment of kinetic energy is thought to play an important role in the dynamics of very large wind farms (Calaf et al., Phys Fluids 2010; and Cal et al. J. Ren. Sust. Energy 2010). To elucidate dominant mechanisms and flow physics of this vertical transfer of kinetic energy, we use Proper Orthogonal Decomposition (POD) to extract dominant flow structures from snapshots of velocity fields generated using Large Eddy Simulation of flow in an infinite turbine array in the atmospheric boundary layer. The POD analysis shows that the dominant modes are large streamwise counter-rotating vortices located above the turbines. The contribution of each POD mode to kinetic energy entrainment at the turbine level is then quantified and the modes are ordered by this contribution. Interestingly, the number of POD modes needed to represent dominant portions of the kinetic energy entrainment is less that the number needed to represent similar portions of the kinetic energy in the turbulent field. This suggests that understanding and controlling only a small number of flow structures may be relevant to the design of very large wind farms. In addition, to understand how the array layout affects the POD modes, several turbine orientations (aligned, staggered, etc) will be discussed. This research is supported by a NSF Graduate Fellowship and by NSF-CBET 1133800. Computer time by NCAR is also appreciated.

  19. 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.

  20. Non isothermal decomposition of lanthanum titanates precursors prepared by sol gel process: A kinetic and thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Bassil, S. [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France); Kaddouri, A., E-mail: akim.kaddouri@ircelyon.univ-lyon1.fr [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France); Béguin, B.; Gélin, P. [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France)

    2013-09-10

    Highlights: ► Metal-propionates is a most promising route for the preparation of La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} (LST) at a temperature substantially lower than that used for the preparation of the same solid by traditional methods. ► Activation energy and isothermal thermodynamic parameters calculated for the decomposition process are close to those observed for metal organic compounds. ► Sol gel-prepared LST presented low propensity to coke deposition and high stability with time during the critical long term exposure to methane and steam at high temperatures. - Abstract: The single phase La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} was prepared via the sol gel process using propionic acid. Kinetics of the thermal decomposition of the precursors has been studied using differential thermogravimetry under non-isothermal conditions in different atmospheres (air and helium). Non isothermal kinetic (A and ΔE) and thermodynamic parameters (ΔH, ΔS and Cp) were determined using different heating rates. La{sub 2}O{sub 3}, SrO and TiO{sub 2} products crystallized at temperatures of ca. 730, 960 and 470 °C respectively while pure La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} phase was obtained at 1200 °C, temperature substantially lower than that used for the preparation of La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} by conventional solid state method. Precursors and/or final solids were characterized by thermogravimetric analysis (TG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, diffuse reflectance ultraviolet–visible spectroscopy (DR-UV–vis) and methane steam reforming under water deficient conditions.

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

    African Journals Online (AJOL)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R.; Bulusu, S.

    1991-12-31

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

  3. Kinetics and mechanism of the exothermic first-stage decomposition reaction of 1,3-bis(2,2,2-trinitroethyl)-1,3-diazacyclopentanone-2.

    Science.gov (United States)

    Rong-zu, Hu; De-suo, Yang; Sheng-li, Gao; San-ping, Chen; Hong-an, Zhao; Qi-zhen, Shi

    2003-08-29

    The thermal behavior, mechanism and kinetic parameters of the exothermic first-stage decomposition reaction of the title compound in a temperature-programmed mode have been investigated by means of DSC, TG-DTG and IR. The reaction mechanism was proposed. The kinetic model function in differential form, apparent activation energy (E(a)) and pre-exponential factor (A) of this reaction are (1-alpha)(2), 178.41 kJ mol(-1) and 10(17.06)s(-1), respectively. The critical temperature of thermal explosion of the compound is 184.99 degrees C. The values of DeltaS( not equal ), DeltaH( not equal ) and DeltaG( not equal ) of this reaction are 91.54 J mol(-1)K(-1), 176.86 kJ mol(-1) and 135.83 kJ mol(-1), respectively.

  4. 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

  5. Kinetic study of the gum decomposition from brazilian gasoline; Estudo cinetico da decomposicao da goma oriunda de gasolina brasileira

    Energy Technology Data Exchange (ETDEWEB)

    Pivesso, Paulo Roberto; Galvao, Luzia Patricia Fernandes de Carvalho; Fernandes Junior, Valter Jose; Coutinho, Ana Carla S.L.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Souza, Antonio Gouveia de [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil)

    2004-07-01

    The modern gasoline contains in your composition insatured hydrocarbons that can be degraded by the action of the air, heat and substances presenting catalytic activity. The presence of air and heat promote oxidation reactions and polymerization, which promote the gum formation, that is a product with diverse characteristics. The petroleum and l the automobile industries have been investing in researches to lessen the gum undesirable effects. Nowadays, several products are added to the gasoline, for example, the surfactant additives, with the purpose to reduce the formation of deposits in the engine. This work evaluated the influence of a polyester amine addictive, used as the main active component in Brazilian gasoline. The gums were generated evaporating the gasolines according to the ASTM D 381 method. Two types of gum were obtained; the Common Washed Gum (White Sample) and the Additive based Washed Gum (Additive Sample). Both samples were characterized for thermal analysis and submitted for a kinetic study using the model-free method proposed by Vyazovkin. This approach was applied to the final stage of the gums decomposition, supplying the corresponding relative kinetic parameters, such as energy of activation and conversion (author)

  6. 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.

  7. A collision theory-based derivation of semiempirical equations for modeling dispersive kinetics and their application to a mixed-phase crystal decomposition.

    Science.gov (United States)

    Skrdla, Peter J

    2006-10-12

    In recent works, the author has shown the utility of new, semiempirical kinetic model equations for treating dispersive chemical processes ranging from slow (minute/hour time scale) solid-state phase transformations to ultrafast (femtosecond) reactions in the gas phase. These two fundamental models (one for homogeneous/deceleratory sigmoidal conversion kinetics and the other for heterogeneous/acceleratory sigmoidal kinetics; isothermal conditions), based on the assumption of a "Maxwell-Boltzmann-like" distribution of molecular activation energies, provide a novel, quantum-based interpretation of the kinetics. As an extension to previous work, it is shown here that the derivation of these dispersive kinetic equations is supported by classical collision theory (i.e., for gas-phase applications). Furthermore, the successful application of the approach to the kinetic modeling of the solid-state decomposition of a binary system, CO2.C2H2, is demonstrated. Finally, the models derived appear to explain some of the (solid-state) kinetic data collected using isoconversional techniques such as those often reported in the thermal analysis literature.

  8. Thermal degradation kinetics and antimicrobial studies of terpolymer resins

    Directory of Open Access Journals (Sweden)

    Abdul R. Burkanudeen

    2016-09-01

    Full Text Available The terpolymer (ASF was synthesized by condensation of anthranilic acid and salicylic acid with formaldehyde in the presence of glacial acetic acid as a catalyst at 140 ± 2 °C for 6 h with varying proportions of reactants. The terpolymer ASF-I was characterized by elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy. The thermal decomposition behavior of ASF-I, II and III terpolymers was studied using thermogravimetric analysis (TGA in a static nitrogen atmosphere at a heating rate of 20 °C/min. Freeman–Carroll, Sharp–Wentworth and Phadnis–Deshpande methods were used to calculate the thermal activation energy (Ea the order of reaction (n, entropy change (ΔS, free energy change (ΔF, apparent entropy (S∗ and frequency factor (Z. Phadnis–Deshpande method was used to propose the thermal degradation model for the decomposition pattern of ASF-I terpolymer resin. The order of the decomposition reaction was found to be 0.901. The thermal activation energy determined with the help of these methods was in good agreement with each other. The ASF-I, II and III resins were tested for their inhibitory action against pathogenic bacteria and fungi. The resins show potent inhibitory action against bacteria, such as Escherichia coli, Klebsiella, Staphylococcus aureus and Pseudomonas aeruginosa and fungi viz. Aspergillus flavus, Aspergillus niger, Penicillium sp., Candida albicans, Cryptococcus neoformans and Mucor sp.

  9. Kinetics of the Thermal Degradation of Granulated Scrap Tyres: a Model-free Analysis

    Directory of Open Access Journals (Sweden)

    Félix A. LÓPEZ

    2013-12-01

    Full Text Available Pyrolysis is a technology with a promising future in the recycling of scrap tyres. This paper determines the thermal decomposition behaviour and kinetics of granulated scrap tyres (GST by examining the thermogravimetric/derivative thermogravimetric (TGA/DTG data obtained during their pyrolysis in an inert atmosphere at different heating rates. The model-free methods of Friedman, Flynn-Wall-Ozawa and Coats-Redfern were used to determine the reaction kinetics from the DTG data. The apparent activation energy and pre-exponential factor for the degradation of GST were calculated. A comparison with the results obtained by other authors was made.DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2947

  10. Thermal behavior and kinetic study for catalytic co-pyrolysis of biomass with plastics.

    Science.gov (United States)

    Zhang, Xuesong; Lei, Hanwu; Zhu, Lei; Zhu, Xiaolu; Qian, Moriko; Yadavalli, Gayatri; Wu, Joan; Chen, Shulin

    2016-11-01

    The present study aims to investigate the thermal decomposition behaviors and kinetics of biomass (cellulose/Douglas fir sawdust) and plastics (LDPE) in a non-catalytic and catalytic co-pyrolysis over ZSM-5 catalyst by using a thermogravimetric analyzer (TGA). It was found that there was a positive synergistic interaction between biomass and plastics according to the difference of weight loss (ΔW), which could decrease the formation of solid residue at the end of the experiment. The first order reaction model well fitted for both non-catalytic and catalytic co-pyrolysis of biomass with plastics. The activation energy (E) of Cellulose-LDPE-Catalyst and DF-LDPE-Catalyst are only 89.51 and 54.51kJ/mol, respectively. The kinetics analysis showed that adding catalyst doesn't change the decomposition mechanism. As a result, the kinetic study on catalytic co-pyrolysis of biomass with plastics was suggested that the catalytic co-pyrolysis is a promising technique that can significantly reduce the energy input. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2012-12-01

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

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

    Science.gov (United States)

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

    2017-09-05

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

  13. 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.

  14. Non-isothermal crystallization kinetics and thermal behaviour of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The thermal behaviour and crystallization kinetics of PA12/SEBS-g-MA blends were investigated under non-isothermal and isothermal conditions using thermogravimetric analysis and differential scanning calorimetry, respectively. The macrokinetic model given by Avrami was used to analyse both the non-.

  15. Thermal kinetics using a modified commercial stopped flow apparatus

    Science.gov (United States)

    Malyj, M.; Smith, P. D.; Balko, B.; Berger, R. L.

    1980-07-01

    A commercially available optical and fluorescence stopped flow apparatus has been adapted for thermal detection methods. A minor modification was sufficient to permit the measurement of kinetics of chemical reactions with half lives in the range of 15 ms to several seconds. A detection sensitivity of 1 m °C was obtained.

  16. Modelling of Thermal Degradation Kinetics of Ascorbic Acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

  17. Modelling of thermal degradation kinetics of ascorbic acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

  18. Kinetic study of Mongolian coals by thermal analysis

    Directory of Open Access Journals (Sweden)

    Jargalmaa S

    2018-02-01

    Full Text Available Thermal analysis was used for the thermal characterization of the coal samples. The experiments were performed to study the pyrolysis and gasification kinetics of typical Mongolian brown coals. Low rank coals from Shivee ovoo, Ulaan ovoo, Aduun chuluun and Baganuur deposits have been investigated. Coal samples were heated in the thermogravimetric apparatus under argon at a temperature ranges of 25-1020ºC with heating rates of 10, 20, 30 and 40ºC/min. Thermogravimetry (TG and derivative thermogravimetry (DTG were performed to measure weight changes and rates of weight losses used for calculating the kinetic parameters. The activation energy (Ea was calculated from the experimental results by using an Arrhenius type kinetic model.

  19. 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...

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

    Indian Academy of Sciences (India)

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

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

    Science.gov (United States)

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

    2013-07-01

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

  2. 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.

  3. Detailed kinetic modeling and sensitivity analysis of hydrogen iodide decomposition in sulfur-iodine cycle for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanwei; Zhou, Junhu; Wang, Zhihua; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China)

    2008-01-15

    A new detailed kinetic modeling was developed for homogeneous decomposition of hydrogen iodide (HI) in the sulfur-iodine cycle. Results show the HI decomposition reaction is sensitive to temperature, and the response time of reaction reduces from 1 s to 10 ms as temperature increases from 500 to 800 {sup circle} C. The decomposition is also improved as pressure increased. Kinetic calculations are also compared with the experimental data, and all trends of the experiment can be reproduced by the model. Sensitivity analysis shows that the reactions of HI with HI, H and I play a major role in the hydrogen production process and the hydrogen consumption occurs primarily by reaction of H with I{sub 2} and reaction of I with H{sub 2} to form HI. As temperature increases, different reactions play a dominant role in HI decomposition process. Based on the detailed kinetic modeling and sensitivity analysis results, the HI decomposition reaction path diagram was constructed in this paper. (author)

  4. Kinetic analysis for non-isothermal decomposition of un-irradiated and gamma-irradiated anhydrous cadmium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Culas, S.; Samuel, J. [Mar Ivanios College, Kerala (India). Dept. of Chemistry

    2014-04-01

    The thermal decomposition of untreated and γ-irradiated samples of anhydrous cadmium nitrate was performed under non-isothermal conditions at different heating rates (5, 10, 15 and 20 C min{sup -1}). The results showed that the decomposition proceeds in one major step with the formation of cadmium oxide as solid residue. The data were analysed by using both isoconversional and non-isoconversional methods. The activation energy was calculated by various model-free isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with phase boundary reaction with spherical symmetry (R3 mechanism) for both untreated and irradiated salts at all heating rates. (orig.)

  5. Thermal analysis and combustion kinetic of heavy oils

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.G. [Centre for Petroleum Studies, State University of Campinas(Brazil); Vargas, J.A.V.; Trevisan, O.V. [Department of Petroleum Engineering, Faculty of Mechanical Engineering, State University of Campinas (Brazil)

    2011-07-01

    In the oilfield sector, a thermal method named in-situ combustion (ISC) is used as an enhanced recovery method. ISC consists of the injection of gas into the reservoir, a combustion front is created producing heat which reduces the oil viscosity. For this method to be successful, understanding of the thermal and kinetic parameters involved is required; the aim of this paper is to evaluate those parameters for different crude oils. Experiments were conducted using accelerating rate calorimetry on Brazilian heavy oil samples under a heat-wait-seek-mode. Results showed that accelerating rate calorimetry is efficient in resolving the three main regions of reaction of the oil and that between 200 degree C and 300 degree C oxygen addition reactions are dominant while bond scission reactions dominate from 350 degree C. This study demonstrated that accelerating rate calorimetry is an efficient method to determine thermal and kinetic parameters of oxidation reaction of heavy oil.

  6. 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.

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

    Science.gov (United States)

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zaheer-ud-din Babar

    2017-03-01

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

  9. 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.

  10. 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)

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

    Science.gov (United States)

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

    2014-02-13

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-07

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

  13. 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.

  14. Chemical kinetic performance losses for a hydrogen laser thermal thruster

    Science.gov (United States)

    Mccay, T. D.; Dexter, C. E.

    1985-01-01

    Projected requirements for efficient, economical, orbit-raising propulsion systems have generated investigations into several potentially high specific impulse, moderate thrust, advanced systems. One of these systems, laser thermal propulsion, utilizes a high temperature plasma as the enthalpy source. The plasma is sustained by a focused laser beam which maintains the plasma temperature at levels near 20,000 K. Since such temperature levels lead to total dissociation and high ionization, the plasma thruster system potentially has a high specific impulse decrement due to recombination losses. The nozzle flow is expected to be sufficiently nonequilibrium to warrant concern over the achievable specific impluse. This investigation was an attempt at evaluation of those losses. The One-Dimensional Kinetics (ODK) option of the Two-Dimensional Kinetics (TDK) Computer Program was used with a chemical kinetics rate set obtained from available literature to determine the chemical kinetic energy losses for typical plasma thruster conditions. The rates were varied about the nominal accepted values to band the possible losses. Kinetic losses were shown to be highly significant for a laser thermal thruster using hydrogen. A 30 percent reduction in specific impulse is possible simply due to the inability to completely extract the molecular recombination energy.

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

    OpenAIRE

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

    2015-01-01

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

  16. Kinetic analysis of the termal decomposition of colombian vacuum residua by termogravimetry

    Directory of Open Access Journals (Sweden)

    Fabian Andrey Diaz Mateus

    2015-12-01

    Full Text Available Five different Colombian vacuum residues were thermally decomposed in a thermogravimetric analyzer. Three heating rates were employed to heat the sample up to 650°C. The kinetic analysis was performed by the Coats-Redfern method to describe the non-isothermal pyrolysis of the residua, a reaction model where the reaction order gradually increases from first to second order is proposed and an excellent agreement of the experimental with the calculated data is presented. The results also indicate that the pyrolysis of a vacuum residue cannot be modeled by a single reaction mechanism.

  17. Kinetic analysis of the termal decomposition of colombian vacuum residua by termogravimetry

    Directory of Open Access Journals (Sweden)

    Fabian Andrey Diaz Mateus

    2015-09-01

    Full Text Available Five different Colombian vacuum residues were thermally decomposed in a thermogravimetric analyzer. Three heating rates were employed to heat the sample up to 650°C. The kinetic analysis was performed by the Coats-Redfern method to describe the non-isothermal pyrolysis of the residua, a reaction model where the reaction order gradually increases from first to second order is proposed and an excellent agreement of the experimental with the calculated data is presented. The results also indicate that the pyrolysis of a vacuum residue cannot be modeled by a single reaction mechanism.

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

    Science.gov (United States)

    Micca Longo, G.; Longo, S.

    2017-10-01

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

  19. Ultraviolet Photon-Induced Desorption and Decomposition Kinetics and Dynamics of Methyl Nitrite on SILVER(111)

    Science.gov (United States)

    Pressley, Laura Ann

    The wavelength-dependent cross section for decomposition and surface fragment reaction mechanisms for the photon -induced decomposition of CH_3ONO on Ag(111) are determined using the surface analytical techniques of temperature programmed desorption with mass spectroscopy (TPD), x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively), residual gas analysis with mass spectroscopy (RGA), and secondary ion mass spectroscopy (SIMS). Methyl nitrite adsorbs reversibly on Ag(111) at 100 K with monolayer and multilayer desorption occurring at 131 and 118 K, respectively. The major photodecomposition fragments formed at 100 K include O(a), CH_2 (a), CH_3(a), CH _2O(a), and CH_3O(a). Upon heating to 350 K, these fragments recombine and desorb as H_2 and CH_2OHCH=O. The desorption channel at 350 K accounts for ~ 85% of the available fragments retained on the surface. The remaining fragments react and desorb as CH_3 OCH=O and CH_2OHCH=O at 200 K and 250 K, respectively. The photon-induced desorption dynamics of the nascent fragment, NO, is determined using time-of-flight mass spectroscopy (TOF). At 254, 308, and 313 nm, the translational energy distributions of the desorbing NO is measured at 100 K. Two desorption channels are observed in the TOF spectra at all wavelengths investigated. Irrespective of the excitation wavelength, the flux-weighted mean translational energy, /2k, of the slower channel is around 115 +/- 10 K. We propose that this channel results from an extended interaction of the NO with the Ag(111) surface. The measured /2k of the faster desorption channel of the nascent NO photofragment at 254, 308, and 351 nm is 1980 +/- 100 K, 617 +/- 100 K, and 846 +/- 100 K, respectively. Comparison of the surface and gas phase photochemical kinetics and dynamics indicates that the dominant photodecomposition mechanism on the Ag(111) surface is the direct absorbance of the photon by the adsorbate.

  20. 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.

  1. Thermal and high pressure inactivation kinetics of blueberry peroxidase.

    Science.gov (United States)

    Terefe, Netsanet Shiferaw; Delon, Antoine; Versteeg, Cornelis

    2017-10-01

    This study for the first time investigated the stability and inactivation kinetics of blueberry peroxidase in model systems (McIlvaine buffer, pH=3.6, the typical pH of blueberry juice) during thermal (40-80°C) and combined high pressure-thermal processing (0.1-690MPa, 30-90°C). At 70-80°C, the thermal inactivation kinetics was best described by a biphasic model with ∼61% labile and ∼39% stable fractions at temperature between 70 and 75°C. High pressure inhibited the inactivation of the enzyme with no inactivation at pressures as high as 690MPa and temperatures less than 50°C. The inactivation kinetics of the enzyme at 60-70°C, and pressures higher than 500MPa was best described by a first order biphasic model with ∼25% labile fraction and 75% stable fraction. The activation energy values at atmospheric pressure were 548.6kJ/mol and 324.5kJ/mol respectively for the stable and the labile fractions. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  2. 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.

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Science.gov (United States)

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

    2015-07-30

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

  5. 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.

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

    Science.gov (United States)

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

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

  7. 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.

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

    Science.gov (United States)

    Chrebet, Tomáš; Balog, Karol

    2010-01-01

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

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

    Science.gov (United States)

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

    2011-12-01

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

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

    Science.gov (United States)

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

    2014-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-15

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

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

    DEFF Research Database (Denmark)

    Hälldahl, L.; Sørensen, Ole Toft

    1979-01-01

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

  13. Kinetics of the decomposition and the estimation of the stability of 10% aqueous and non-aqueous hydrogen peroxide solutions

    Directory of Open Access Journals (Sweden)

    Zun Maria

    2014-12-01

    Full Text Available In this study, the stability of 10% hydrogen peroxide aqueous and non-aqueous solutions with the addition of 6% (w/w of urea was evaluated. The solutions were stored at 20°C, 30°C and 40°C, and the decomposition of hydrogen peroxide proceeded according to first-order kinetics. With the addition of the urea in the solutions, the decomposition rate constant increased and the activation energy decreased. The temperature of storage also affected the decomposition of substance, however, 10% hydrogen peroxide solutions prepared in PEG-300, and stabilized with the addition of 6% (w/w of urea had the best constancy.

  14. Thermal inactivation kinetics of β-galactosidase during bread baking.

    Science.gov (United States)

    Zhang, Lu; Chen, Xiao Dong; Boom, Remko M; Schutyser, Maarten A I

    2017-06-15

    In this study, β-galactosidase was utilized as a model enzyme to investigate the mechanism of enzyme inactivation during bread baking. Thermal inactivation of β-galactosidase was investigated in a wheat flour/water system at varying temperature-moisture content combinations, and in bread during baking at 175 or 205°C. In the wheat flour/water system, the thermostability of β-galactosidase increased with decreased moisture content, and a kinetic model was accurately fitted to the corresponding inactivation data (R 2 =0.99). Interestingly, the residual enzyme activity in the bread crust (about 30%) was hundredfold higher than that in the crumb (about 0.3%) after baking, despite the higher temperature in the crust throughout baking. This result suggested that the reduced moisture content in the crust increased the thermostability of the enzyme. Subsequently, the kinetic model reasonably predicted the enzyme inactivation in the crumb using the same parameters derived from the wheat flour/water system. However, the model predicted a lower residual enzyme activity in the crust compared with the experimental result, which indicated that the structure of the crust may influence the enzyme inactivation mechanism during baking. The results reported can provide a quantitative understanding of the thermal inactivation kinetics of enzyme during baking, which is essential to better retain enzymatic activity in bakery products supplemented with heat-sensitive enzymes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Thermodynamics and kinetics of decomposition of Al{sub 2}TiO{sub 5}-base ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Buscaglia, V.; Leoni, M. [CNR, Genoa (Italy). ICFAM; Nanni, P. [Facolta di Ingegneria, Univ. di Genova (Italy)

    1997-12-31

    The decomposition of Mg{sub x}Al{sub 2(1-x)}Ti{sub (1+x)}O{sub 5} solid solutions with x = 0 (Al{sub 2}TiO{sub 5}), 0.1 and 0.2 was studied at 1100 C. The kinetics follows the Avrami equation with a time exponent of 1.6 for x = 0 and 3/3.5 for x = 0.1 and 0.2. Decomposition of materials with x > 0 is considerably delayed in comparison to pure Al{sub 2}TiO{sub 5}: the time of half-transformation into parent oxides is increased by an order of magnitude. The microstructure of partially decomposed materials show the presence of nodules with a core composed of Al{sub 2}O{sub 3} (and MgAl{sub 2}O{sub 4} when x > 0) elongated crystal, surrounded by an irregular TiO{sub 2} shell. The nodules grow retaining their structure as decomposition proceeds. The decomposition kinetics is probably controlled by the nucleation of the reaction product at a limited number of ``easy to nucleate`` sites owing to the small chemical driving force available. (orig.) 11 refs.

  16. Thermolysis, nonisothermal decomposition kinetics, specific heat capacity and adiabatic time-to-explosion of [Cu(NH3)4](DNANT)2 (DNANT= dinitroacetonitrile).

    Science.gov (United States)

    Zhang, Yu; Wu, Hao; Xu, Kangzhen; Zhang, Wantao; Ren, Zhaoyu; Song, Jirong; Zhao, Fengqi

    2014-02-20

    A new energetic copper complex of dinitroacetonitrile (DNANT), [Cu(NH3)4](DNANT)2, was first synthesized through an unexpected reaction. The thermal decomposition of [Cu(NH3)4](DNANT)2 was studied with DSC and TG/DTG methods. The gas products were analyzed through a TG-FTIR-MS method. The nonisothermal kinetic equation of the exothermic process is dα/dT = 10(10.92)/β4(1 - α)[-ln(1 - α)](3/4) exp(-1.298 × 10(5)/RT). The self-accelerating decomposition temperature and critical temperature of thermal explosion are 217.9 and 221.0 °C. The specific heat capacity of [Cu(NH3)4](DNANT)2 was determined with a micro-DSC method, and the molar heat capacity is 512.6 J mol(-1) K(-1) at 25 °C. Adiabatic time-to-explosion of Cu(NH3)4(DNANT)2 was also calculated to be about 137 s.

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

    Science.gov (United States)

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

    2014-07-15

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

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

    Science.gov (United States)

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

    2017-11-01

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

  19. 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.

  20. Solution for the nuclear reactor point-kinetics problem via decomposition method; Solucao via metodo da decomposicao do problema de cinetica puntual de um reator nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Rubem Mario Figueiro [Pontificia Univ. Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil). Faculdade de Engenharia. Dept. de Engenharia Quimica]. E-mail: rvargas@pucrs.br; Vilhena, Marco Tullio de [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Matematica]. E-mail: vilhena@mat.ufrgs.br; Cardona, Augusto Vieira [Pontificia Univ. Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil). Faculdade de Matematica]. E-mail: acardona@pucrs.br

    2005-07-01

    The decomposition method is a mathematical technique, usually, applied to solve nonlinear problems, but can be an effective procedure for analytical solution of linear problems presenting advantages when compared with others techniques. In this work, an analytical solution for the nuclear reactor point-kinetics equations is developed using the decomposition method. (author)

  1. 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.

  2. 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.

  3. Thermodynamics and kinetics of NaAlH4 nanocluster decomposition.

    Science.gov (United States)

    Bhakta, Raghunandan K; Maharrey, Sean; Stavila, Vitalie; Highley, Aaron; Alam, Todd; Majzoub, Eric; Allendorf, Mark

    2012-06-14

    Reactive nanoparticles are of great interest for applications ranging from catalysis to energy storage. However, efforts to relate cluster size to thermodynamic stability and chemical reactivity are hampered by broad pore size distributions and poorly characterized chemical environments in many microporous templates. Metal hydrides are an important example of this problem. Theoretical calculations suggest that reducing their critical dimension to the nanoscale can in some cases considerably destabilize these materials and there is clear experimental evidence for accelerated kinetics, making hydrogen storage applications more attractive in some cases. However, quantitative measurements establishing the influence of size on thermodynamics are lacking, primarily because carbon aerogels often used as supports provide inadequate control over size and pore chemistry. Here, we employ the nanoporous metal-organic framework (MOF) Cu-BTC (also known as HKUST-1) as a template to synthesize and confine the complex hydride NaAlH(4). The well-defined crystalline structure and monodisperse pore dimensions of this MOF allow detailed, quantitative probing of the thermodynamics and kinetics of H(2) desorption from 1-nm NaAlH(4) clusters (NaAlH(4)@Cu-BTC) without the ambiguity associated with amorphous templates. Hydrogen evolution rates were measured as a function of time and temperature using the Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry method, in which sample mass changes are correlated with a complete analysis of evolved gases. NaAlH(4)@Cu-BTC undergoes a single-step dehydrogenation reaction in which the Na(3)AlH(6) intermediate formed during decomposition of the bulk hydride is not observed. Comparison of the thermodynamically controlled quasi-equilibrium reaction pathways in the bulk and nanoscale materials shows that the nanoclusters are slightly stabilized by confinement, having an H(2) desorption enthalpy that is 7 kJ (mol H(2))(-1) higher than the

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-02-28

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

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

    Science.gov (United States)

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

    2011-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-03-20

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

  7. 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.

  8. Thermal degradation kinetics of polylactic acid/acid fabricated cellulose nanocrystal based bionanocomposites.

    Science.gov (United States)

    Monika; Dhar, Prodyut; Katiyar, Vimal

    2017-11-01

    Cellulose nanocrystals (CNC) are fabricated from filter paper (as cellulosic source) by acid hydrolysis using different acids such as sulphuric (H2SO4), phosphoric (H3PO4), hydrochloric (HCl) and nitric (HNO3) acid. The resulting acid derived CNC are melt mixed with Polylactic acid (PLA) using extruder at 180°C. Thermogravimetric (TGA) result shows that increase in 10% and 50% weight loss (T10, T50) temperature for PLA-CNC film fabricated with HNO3, H3PO4 and HCl derived CNC have improved thermal stability in comparison to H2SO4-CNC. Nonisothermal kinetic studies are carried out with modified-Coats-Redfern (C-R), Ozawa-Flynn-Wall (OFW) and Kissinger method to predict the kinetic and thermodynamic parameters. Subsequently prediction of these parameter leads to the proposal of thermal induced degradation mechanism of nanocomposites using Criado method. The distribution of Ea calculated from OFW model are (PLA-H3PO4-CNC: 125-139 kJmol(-1)), (PLA-HNO3-CNC: 126-145 kJmol(-1)), (PLA-H2SO4-CNC: 102-123 kJmol(-1)) and (PLA-HCl-CNC: 140-182 kJmol(-1)). This difference among Ea for the decomposition of PLA-CNC bionanocomposite is probably due to various acids used in this study. The Ea calculated by these two methods are found in consonance with that observed from Kissinger method. Further, hyphenated TG-Fourier transform infrared spectroscopy (FTIR) result shows that gaseous products such as CO2, CO, lactide, aldehydes and other compounds are given off during the thermal degradation of PLA-CNC nanocomposite. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-10

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

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

    Directory of Open Access Journals (Sweden)

    Koumoulos Elias P.

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Abolfazl Shiroudi

    2015-09-01

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

  13. Experimental and Kinetic Modeling Study of Nitroethane Pyrolysis at a Low Pressure: Competition Reactions in the Primary Decomposition

    DEFF Research Database (Denmark)

    Zhang, Kuiwen; Glarborg, Peter; Zhou, Xueyao

    2016-01-01

    and molecular beam sampling techniques. The rate constants for the primary pyrolysis of nitroethane as well as those for the decomposition of the secondary product CH3CHNO2 have been obtained via ab initio calculations. These results have been adopted in a detailed chemical kinetic model, which contains 95...... species and 737 reactions. The model was validated against the experimental results with satisfactory agreement for most of the identified and quantified species. Further analysis on the results indicates that both the concerted molecular elimination and C-N bond rupture are significant in the primary...... pyrolysis of nitroethane, with the latter channel being more important at high temperatures. The adoption of new decomposition pathways of CH3CHNO2 has resulted in reasonable predictions for relevant intermediates....

  14. 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.

  15. Thermal Spectroscopy and Kinetic Studies of PEO/PVDF Loaded by Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Laila Hussein Gaabour

    2015-01-01

    Full Text Available Nanocomposites of polyethylene oxide (PEO and polyvinylidene fluoride (PVDF without and with low content of single and multiwalled carbon nanotubes (SWCNTs-MWCNTs were prepared and studied by thermogravimetric analysis (TGA using different heating rate. TGA results indicate that the thermal stability of neat PEO/PVDF blend was improved with both heating rate and incorporation of carbon nanotubes (CNTs. The degradation temperature for neat blend was lower than those of the nanocomposites after adding both SWCNTs and MWCNTs. As increase of heating rate, the onset of decomposition is irregularly moved to higher temperatures. This indicates that the thermal stability of the polymeric matrices has been improved after addition of CNTs. The residual weight of the samples left increased steadily with adding of both SWCNTs and MWCNTs. Kinetic thermodynamic parameters such as activation energy, enthalpy, entropy, and Gibbs free energy are evaluated from TGA data using Coats-Redfern model. The values of all parameters irregularly decrease with increasing of heating rate due to increasing of heating rate temperature, the random scission of macromolecule chain in the polymeric matrices predominates and the activation energy has a lower value.

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

    Directory of Open Access Journals (Sweden)

    2010-06-01

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

  17. 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.

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

    Science.gov (United States)

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

    2015-03-05

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

  19. 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.

  20. 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.

  1. Influence of Ca2+ or Na+ extraframework cations on the thermal dehydration and related kinetic performance of LSX zeolite

    Science.gov (United States)

    Panezai, Hamida; Fan, Minghui; Sun, Jihong; Bai, Shiyang; Wu, Xia

    2016-12-01

    Nitrogen adsorption performances of low-silica type X zeolites (LSX) containing Na+ or Ca2+ ions were studied and compared with Li+ ion, and their structural and thermal properties were investigated using various characterizations (XRD, TG-DTG, BET, XPS, SEM, TEM, and EDX with elemental mapping techniques). The kinetics of their thermal dehydration and decomposition was studied using thermogravimetry at three rates (5, 10, and 15 K/min) of linear increase of temperature under non-isothermal heating. Two model free procedures named, Kissinger, and Flynn-Wall-Ozawa (iso-conversional) and one model fitting method called Coats-Redfern based on single TG curves, as well as 41 mechanism functions were used. The kinetic parameters (apparent activation energy E, pre-exponential factor A and model) of the three phases for each sample obtained from the non-isothermal methods were then compared with the results from iso-conversional methods this showed that they strongly depend on the selection of appropriate mechanism function and the corresponding kinetic model from the perspective of crystal structure used. The results demonstrated that the E value obtained at low temperature was lower than that at high temperature, implying that the dehydration process of physisorbed water belongs to diffusion-based control, while decomposition of bonded water (chemisorbed) belongs to kinetic-based control at high temperature. These comparisons allow us to underline the strong effect of cations in association with water and their distribution in the micropores of LSX on the N2 adsorption performance.

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

    Science.gov (United States)

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

    2013-05-01

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

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

    Science.gov (United States)

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

    2014-03-13

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

  4. Thermolysis kinetics and thermal degradation compounds of alliin.

    Science.gov (United States)

    Chen, Zixing; Xu, MingJiao; Wang, Chao; Zhou, Hua; Fan, Lokyee; Huang, Xuesong

    2017-05-15

    To investigate thermolysis kinetics and identify degradation compounds, alliin solutions were heated at 60, 80, and 89°C. The degradation compounds of alliin were identified by high performance liquid chromatography-mass spectrometry (HPLC-MS), tandem mass spectrometry (MS/MS) and ultra-pressure liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). The results showed that the thermal degradation kinetic of alliin could be described by a first-order reaction and k=4.38×1017exp (-142494/RT), where k is the reaction rate constant, min-1; R is gas constant; T is the absolute temperature, K. Degraded compounds, including S-allyl-l-cysteine and ethers, such as allyl alanine disulfide, allyl alanine trisulfide, allyl alanine tetrasulfide, dialanine disulfide (cysteine), dialanine trisulfide and dialanine tetrasulfide, were identified by HPLC-MS, MS/MS and UPLC-HRMS. Allyl alanine tetrasulfide was identified for the first time in alliin. The results show that alliin is unstable and significant numbers of organosulfur compounds are generated under high temperature treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. The thermal properties of a carbon nanotube-enriched epoxy: Thermal conductivity, curing, and degradation kinetics

    KAUST Repository

    Ventura, Isaac Aguilar

    2013-05-31

    Multiwalled carbon nanotube-enriched epoxy polymers were prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes (COOH-MWCNTs). Three weight ratio configurations (0.05, 0.5, and 1.0 wt %) of COOH-MWCNTs were considered and compared with neat epoxy and ethanol-treated epoxy to investigate the effects of nano enrichment and processing. Here, the thermal properties of the epoxy polymers, including curing kinetics, thermal conductivity, and degradation kinetics were studied. Introducing the MWCNTs increased the curing activation energy as revealed by differential scanning calorimetry. The final thermal conductivity of the 0.5 and 1.0 wt % MWCNT-enriched epoxy samples measured by laser flash technique increased by up to 15% compared with the neat material. The activation energy of the degradation process, investigated by thermogravimetric analysis, was found to increase with increasing CNT content, suggesting that the addition of MWCNTs improved the thermal stability of the epoxy polymers. © 2013 Wiley Periodicals, Inc.

  6. Thermodynamics of the formation of cerium(IV) malonate complex and the kinetics of its redox decomposition

    Science.gov (United States)

    Voskresenskaya, O. O.; Skorik, N. A.; Yuzhakova, Yu. V.

    2017-04-01

    Thermodynamic and kinetic characteristics of cerium(IV) malonate complex formed in the first stage of cerium(IV) oxidation by malonic acid H2Mal are studied using a spectrophotometer, a photometer, and a pH-meter at a ionic strength of I = 2 in the pH region of 0.3-1.6 in a sulfuric acid medium at a temperature of 296.8 K. Its composition is found to be CeOHMal+. The form of organic ligand is Mal2-; the thermodynamic parameters of its formation and kinetic parameters of its intramolecular redox decomposition are determined. The most likely scheme of the initial stages of redox proceeding in the Ce4+-SO 4 2- -H2Mal system is discussed, and a quantitative model of it is proposed.

  7. Kinetic analysis of the thermal isomerisation pathways in an asymmetric double azobenzene switch

    NARCIS (Netherlands)

    Robertus, Jort; Reker, Siebren F.; Pijper, Thomas C.; Deuzeman, Albert; Browne, Wesley R.; Feringa, Ben L.

    2012-01-01

    Here we report a photochemical and kinetic study of the thermal relaxation reaction of a double azobenzene system, in which two azobenzene photochromic units are connected via a phenyl ring. Upon UV irradiation, three thermally unstable isomers are formed. Kinetic studies using arrayed H-1-NMR

  8. Kinetic thermal structure in turbulent Rayleigh-Bénard convection

    Science.gov (United States)

    Chen, Jun; Yin, Ze-Xia; She, Zhen-Su; Bao, Yun

    2017-11-01

    Plumes are believed to be the most important heat carrier in turbulent Rayleigh-Bénard convection (RBC). However, a physically sound and clear definition of plume is still absent. We report here the investigation of a definition of plume called kinetic thermal structure (KTS), based on the analysis of vertical velocity gradient (Λ = ∂w / ∂z), using direct numerical simulation (DNS) data of the three-dimensional RBC in a rectangular cell for Pr = 0.7 and Ra = 1 ×108 5 ×109 . It is shown that the conditional average of temperature on Λ exhibits such a behavior that when Λ is larger than a threshold, the volume carries a constant temperature of fluid, hence defines an unambiguous thermal structure, KTS. The DNS show that the KTS behaves in a sheet-like shape near the conducting plate, and becomes slender and smaller with increasing Ra . The heat flux carried by KTS displays a scaling law, with an exponent larger than the global- Nu - Ra scaling, indicating stronger heat transport than the turbulent background. An advantage of the KTS is its connection to the balance equation allowing, for the first time, a prediction of the Ra -dependence of its vertical velocity and the characteristic Λ threshold, validated by DNS. Supported by NSFC (11172006, 11221062, 11452002), and by MOST (China) 973 project (2009CB724100).

  9. Thermal Behaviour and Detonation Characterization of N-Benzoyl-3 ...

    African Journals Online (AJOL)

    NICO

    The kinetic parameters of the intense exothermic decomposition process were obtained from the analysis of the DSC curves. The apparent ... decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic ..... Substituting the corresponding data into the Smith equation.

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

    Science.gov (United States)

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

    2012-04-01

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

  11. A kinetic study on decomposition of proton-bound dimer using data obtained by ion mobility spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jazan, Elham, E-mail: jazan@iaush.ac.ir; Ghazali Khoob, Abdolhosein S.

    2014-08-17

    Graphical abstract: - Highlights: • The capability of corona discharge-IMS for easy study of kinetic properties was confirmed. • An equation for measuring the rate constant of the proton-bound dimer decomposition reaction was derived. • The effects of temperatures and sample concentration were investigated for monomer–dimer tail. - Abstract: In this study, an equation for measuring the rate constant of the proton-bound dimer decomposition reaction was derived using the data obtained by ion mobility spectrometry (IMS) technique. The ion mobility spectra of cyclohexanone (as the test compound) were obtained at various temperatures and different electric fields. The applied electric field for each temperature was varied between 375 and 500 V cm{sup −1} and the rate constant values of 188.24, 180.54, 280.64, 288.34 and 379.60 s{sup −1} were obtained at different temperatures of 463, 468, 473, 478 and 483 K, respectively. Subsequently, the activation energy and pre-exponential factor were calculated to be 69.5 kJ mol{sup −1} and 1.2 × 10{sup 10} s{sup −1}, respectively. In addition, the standard enthalpy changes were calculated for the dimer decomposition reaction of cyclohexanone at the above-mentioned temperatures.

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-12-30

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

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

    Science.gov (United States)

    Patel, Trushit; Meher, Ramakanta

    2017-09-01

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

  16. 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.

  17. 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.

  18. Computational study on decomposition kinetics of CH3CFClO radical

    Indian Academy of Sciences (India)

    MS received 23 September 2009; revised 30 March 2011; accepted 13 June 2011. Abstract. The present study deals with the decomposition of haloalkoxy radical (CH3CFClO) formed from. 1,1-dichloro-1-fluoroethane (HCFC-141b) ...... Curtiss L A, Redfern P C, Smith B J and Radom Leo. 1996 J. Chem. Phys. 104 5148. 26.

  19. THE EFFECT OF DNOM PROPERTIES ON THE KINETICS OF OZONE DECOMPOSITION AND HYDROXYL RADICAL SCAVENGING

    Science.gov (United States)

    The influence of temperature, pH, alkalinity, and type and concentration of the dissolved organic matter (DOM) on the rate of ozone (O3) decomposition, O3-exposure, *OH-exposure and the ratio R ct of the concentrations of *OH and O3 has been studied. For a standardized single oz...

  20. Multistep kinetic behavior in the thermal degradation of poly(L-lactic acid): a physico-geometrical kinetic interpretation.

    Science.gov (United States)

    Yoshikawa, Masahiro; Goshi, Yuri; Yamada, Shuto; Koga, Nobuyoshi

    2014-09-25

    A physico-geometrical kinetic interpretation of the thermal degradation of poly(L-lactic acid) (PLLA) is described based on the results of a kinetic study using thermogravimetry (TG) and the microscopic observation of the reaction process. From the physico-geometrical viewpoint, the reaction process is separated into two different stages characterized by a surface reaction of the molten PLLA in the initial reaction stage followed by continuous bubble formation and disappearance in the established reaction stage. The generally reported trend of variation in the apparent activation energy as the reaction advances is explained by the partial overlapping of these two reaction stages. The kinetic rate data obtained using TG were kinetically separated into those for the respective reaction stages by optimizing the kinetic parameters. The significance of the kinetic results is discussed in terms of the physico-geometrical characteristics of the reaction. Such systematic kinetic analyses demonstrate the importance of considering the physico-geometrical perspective when interpreting the kinetic results for the thermal degradation of polymers.

  1. 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.

  2. 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

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

    Directory of Open Access Journals (Sweden)

    Polyakov Vyacheslav Sergeevich

    2012-07-01

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

  4. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-30

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

  6. Decomposition kinetics of ammonia in gaseous stream by a nanoscale copper-cerium bimetallic catalyst.

    Science.gov (United States)

    Hung, Chang-Mao

    2008-01-15

    This study performance is to examine the kinetics over nanoscale copper-cerium bimetallic catalyst under selective catalytic oxidation (SCO) of ammonia to N(2) in a tubular fixed-bed reactor (TFBR) at temperatures from 150 to 400 degrees C in the presence of oxygen. The nanoscale copper-cerium bimetallic catalyst was prepared by co-precipitation with Cu(NO(3))(2) and Ce(NO(3))(3) at molar ratio of 6:4. Experimental results showed that the catalyst with transmission electron microscopy (TEM) revealed that copper and cerium are well dispersed and catalyst in the form of nanometer-sized particles. Moreover, the kinetic behavior of NH(3) oxidation with catalysis can be accounted by using the rate expression of the Langmuir-Hinshelwood type kinetic model. Kinetic parameters are also developed on the basis of the differential reactor data. Also, experimental results are compared with those of the model predicted.

  7. Thermal degradation kinetics of bixin in an aqueous model system.

    Science.gov (United States)

    Rios, Alessandro de O; Borsarelli, Claudio D; Mercadante, Adriana Z

    2005-03-23

    The kinetics of the thermal degradation of the natural cis carotenoid bixin in a water/ethanol (8:2) solution was studied as a function of temperature (70-125 degrees C), using high-performance liquid chromatography. The curves for the decay of bixin and formation of products (e.g., di-cis and all-trans isomers and a C17 degradation compound) did not adjust well to a first-order rate law, but very good fits were obtained using a biexponential model. This mathematical modeling gave the rate constant values for the formation of the primary products from bixin, and the energy barrier for each step was obtained. The di-cis isomers were formed immediately (15 kcal/mol) together with the decay of bixin, followed by a slow consumption, indicating their role as reaction intermediates. In fact, the di-cis isomers could easily revert to bixin (Ea approximately 3 kcal/mol) or yield the primary C17 degradation product, with an energy barrier of 6.5 kcal/mol. In turn, 24 kcal/mol was necessary for the Bix --> all-trans step, explaining its slower formation.

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

    Science.gov (United States)

    Zhou, Rong; Basile, Franco

    2017-09-05

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

  9. Decomposition kinetics of peroxynitrite: influence of pH and buffer.

    Science.gov (United States)

    Molina, Christian; Kissner, Reinhard; Koppenol, Willem H

    2013-07-21

    The decay of ONOOH near neutral pH has been examined as a function of isomerization to H(+) and NO3(-), and decomposition to NO2(-) and O2via O2NOO(-). We find that in phosphate buffer k(isomerization) = 1.11 ± 0.01 s(-1) and k(disproportionation) = (1.3 ± 0.1) × 10(3) M(-1) s(-1) at 25 °C and I = 0.2 M. In the presence of 0.1 M tris(hydroxymethyl)aminomethane (Tris), the decay proceeds more rapidly: k(disproportionation) = 9 × 10(3) M(-1) s(-1). The measured first half-life of the absorbance of peroxynitrite correlates with [Tris]0·([ONOO(-)]0 + [ONOOH]0)(2), where the subscript 0 indicates initial concentrations; if this function exceeds 6.3 × 10(-12) M(3), then Tris significantly accelerates the decomposition of peroxynitrite.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-28

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

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

    Science.gov (United States)

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

    2017-02-28

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

  12. Decomposition mechanisms and kinetics of novel energetic molecules BNFF-1 and ANFF-1: quantum-chemical modeling.

    Science.gov (United States)

    Tsyshevsky, Roman V; Kuklja, Maija M

    2013-07-18

    Decomposition mechanisms, activation barriers, Arrhenius parameters, and reaction kinetics of the novel explosive compounds, 3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole (BNFF-1), and 3-(4-amino-1,2,5-oxadiazol-3-yl)-4-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole (ANFF-1) were explored by means of density functional theory with a range of functionals combined with variational transition state theory. BNFF-1 and ANFF-1 were recently suggested to be good candidates for insensitive high energy density materials. Our modeling reveals that the decomposition initiation in both BNFF-1 and ANFF-1 molecules is triggered by ring cleavage reactions while the further process is defined by a competition between two major pathways, the fast C-NO₂ homolysis and slow nitro-nitrite isomerization releasing NO. We discuss insights on design of new energetic materials with targeted properties gained from our modeling.

  13. Decomposition Mechanisms and Kinetics of Novel Energetic Molecules BNFF-1 and ANFF-1: Quantum-Chemical Modeling

    Directory of Open Access Journals (Sweden)

    Maija M. Kuklja

    2013-07-01

    Full Text Available Decomposition mechanisms, activation barriers, Arrhenius parameters, and reaction kinetics of the novel explosive compounds, 3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl-1,2,5-oxadiazole (BNFF-1, and 3-(4-amino-1,2,5-oxadiazol-3-yl-4-(4-nitro-1,2,5-oxadiazol-3-yl-1,2,5-oxadiazole (ANFF-1 were explored by means of density functional theory with a range of functionals combined with variational transition state theory. BNFF-1 and ANFF-1 were recently suggested to be good candidates for insensitive high energy density materials. Our modeling reveals that the decomposition initiation in both BNFF-1 and ANFF-1 molecules is triggered by ring cleavage reactions while the further process is defined by a competition between two major pathways, the fast C-NO2 homolysis and slow nitro-nitrite isomerization releasing NO. We discuss insights on design of new energetic materials with targeted properties gained from our modeling.

  14. Kinetics of diffusive decomposition in the case of several mass transfer mechanisms

    Science.gov (United States)

    Alexandrov, D. V.

    2017-01-01

    An analytical description of the final stage of diffusive decomposition leaning upon the Slezov theory is developed for several mass transfer mechanisms. The process of formation and relaxation of the crystal size distribution function from the initial ripening stage to its final state corresponding to the universal distribution is studied. The boundary points of a transition region responsible for the tails of the distribution functions on the right of the relevant stopping points are found analytically. The explicit time-dependent analytical expressions for the distribution function and particle growth rates are derived with allowance for the plausible mechanisms of mass transfer.

  15. A kinetic study of the thermal degradation of cetyltrimethylammonium bromide inside the mesoporous SBA-3 molecular sieve

    Directory of Open Access Journals (Sweden)

    DJORDJE STOJAKOVIC

    2007-12-01

    Full Text Available The thermal degradation of cetyltrimethylammonium bromide (CTMAB inside the mesoporous SBA-3 was studied under non-isothermal conditions. There are two distinct and complex kinetic processes which partly overlap, each consisting of one dominant and three minor individual processes. The two dominant processes can be described by the Sestak–Berggren model. The main decomposition step (the first dominant process involves the overcoming of weak interactions between CTMAB and the silica network and proceeds with a lower Ea value (116±2 kJ mol‑1 than the second dominant process (153±5 kJ mol-1, which can be explained by the size reduction of the pore openings due to the contraction of the SBA-3 unit cell caused by the removal of CTMAB.

  16. A kinetic study on the decomposition of 5-hydroxymethylfurfural into levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2006-01-01

    Levulinic acid (LA), accessible by the acid catalyzed degradation of biomass, is potentially a very versatile green intermediate chemical for the synthesis of various (bulk) chemicals for applications like fuel additives, polymers, and resin precursors. We report here a kinetic study on one of the

  17. Numerical simulation and decomposition of kinetic energy in the Central Mediterranean: insight on mesoscale circulation and energy conversion

    Directory of Open Access Journals (Sweden)

    R. Sorgente

    2011-08-01

    Full Text Available The spatial and temporal variability of eddy and mean kinetic energy of the Central Mediterranean region has been investigated, from January 2008 to December 2010, by mean of a numerical simulation mainly to quantify the mesoscale dynamics and their relationships with physical forcing. In order to understand the energy redistribution processes, the baroclinic energy conversion has been analysed, suggesting hypotheses about the drivers of the mesoscale activity in this area. The ocean model used is based on the Princeton Ocean Model implemented at 1/32° horizontal resolution. Surface momentum and buoyancy fluxes are interactively computed by mean of standard bulk formulae using predicted model Sea Surface Temperature and atmospheric variables provided by the European Centre for Medium Range Weather Forecast operational analyses. At its lateral boundaries the model is one-way nested within the Mediterranean Forecasting System operational products.

    The model domain has been subdivided in four sub-regions: Sardinia channel and southern Tyrrhenian Sea, Sicily channel, eastern Tunisian shelf and Libyan Sea. Temporal evolution of eddy and mean kinetic energy has been analysed, on each of the four sub-regions, showing different behaviours. On annual scales and within the first 5 m depth, the eddy kinetic energy represents approximately the 60 % of the total kinetic energy over the whole domain, confirming the strong mesoscale nature of the surface current flows in this area. The analyses show that the model well reproduces the path and the temporal behaviour of the main known sub-basin circulation features. New mesoscale structures have been also identified, from numerical results and direct observations, for the first time as the Pantelleria Vortex and the Medina Gyre.

    The classical kinetic energy decomposition (eddy and mean allowed to depict and to quantify the permanent and fluctuating parts of the circulation in the region, and

  18. Influence of the aromatic substitutes in the thermal and kinetic behavior of mesoionic compounds of the 1,3-thiazole-5-tiolate system

    Energy Technology Data Exchange (ETDEWEB)

    Alves de Morais, Soraya, E-mail: sorayaamorais@yahoo.com.b [Universidade Estadual da Paraiba, Departamento de Quimica, Av. Baraunas, s/n, Campina Grande, PB (Brazil); Rogrigues da Silva Morais, Crislene, E-mail: crislene@pq.cnpq.b [Universidade Federal de Campina Grande, Unidade Academica de Engenharia de Materiais, Av. Aprigio Veloso, 882, Campina Grande, PB (Brazil); Filgueiras de Athayde Filho, Petronio, E-mail: athayde-filho@pq.cnpq.b [Universidade Federal da Paraiba, Departamento de Quimica - CCEN, 58.081-970, Joao Pessoa, PB (Brazil); Freitas Lira, Bruno, E-mail: brunofrlira@hotmail.co [Universidade Federal da Paraiba, Departamento de Quimica - CCEN, 58.081-970, Joao Pessoa, PB (Brazil); Feitosa de Souza, Marcos Antonio, E-mail: ramcos31@yahoo.com.b [Universidade Federal da Paraiba, Departamento de Quimica - CCEN, 58.081-970, Joao Pessoa, PB (Brazil)

    2010-04-16

    In this work, three mesoionic compounds of the 1,3-thiazole-5-tiolat system were studied, derived from amino acids of the glycerin through 1,3-dipolar cyclo-addition/reversion reaction. The mesoionic compounds were characterized as: MI-1 (mesoionic 2-(4-chlorophenyl)-3-methyl-4-phenyl-1,3-thiazole-5-tiolat); MI-2 (mesoionic 2-(4-chlorophenyl)-3-methyl-4-(4-isopropylphenyl)-1,3-thiazole-5-tiolat) and MI-3 (Mesoionic 2-(4-clorophenyl)-3-methyl-4-(methoxyphenyl)-1,3-thiazole-5-tiolate). These compounds were characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), thermogravimetry (TG) and differential scanning calorimeter (DSC). Also, the kinetic study of the thermal decomposition by non-isothermal thermogravimetry has been realized, presenting, the kinetic and thermal behavior of these compounds. The results of the spectroscopic analysis confirmed the structure of the synthesized mesoionic compounds. The DSC curves of the mesoionic compounds MI-1, MI-2, and MI-3 indicated the fusion of two of them followed by a subsequent decomposition. The TG/DTG curves showed that the decomposition of the mesoionic compounds MI-1, MI-2 and MI-3 occurred in several steps.

  19. 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

  20. Mathematical description of pH-stat kinetic traces measured during photochemical quinone decomposition.

    Science.gov (United States)

    Kiss, Virág; Lehoczki, Gábor; Ősz, Katalin

    2017-04-12

    Substituted 1,4-benzoquinone (QR) derivatives are photosensitive in aqueous solution and form hydroquinones (QR-H2) and hydroxy-quinones (QR-OH), two weak acids in their photoreaction. For this reason, the kinetics of the photoreaction can be conveniently followed by the pH-stat titration technique. The mathematical description of the kinetic traces measured provides the two main parameters of the photoreaction: the differential quantum yield of the reaction (Φ) and the ratio of the two photo-products, i.e. the fraction of QR that is converted to QR-OH (α). These values are described in this paper for 2,5-dichloro-1,4-benzoquinone at different pH values, together with the detailed mathematical evaluation of the application limits of the pH-stat method for such reactions.

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

    Science.gov (United States)

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

    2004-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-10-01

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

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

    Science.gov (United States)

    2013-01-01

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

  4. 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%.

  5. 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.

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

    Science.gov (United States)

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

    2017-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Huba, ZJ; Carpenter, EE

    2014-06-06

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

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

    Science.gov (United States)

    Matsugi, Akira; Shiina, Hiroumi

    2014-08-28

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

  9. 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

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

    Science.gov (United States)

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

    2017-06-22

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

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2017-04-01

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

  14. 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.

  15. Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy.

    Science.gov (United States)

    Wheeler, Jeffrey L; Pugh, McKinley; Atkins, S Jake; Porter, Jason M

    2017-12-01

    In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

  16. 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.

  17. 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.

  18. Synthesis and Thermal Degradation Kinetics of Co(II, Ni(II, Cd(II, Zn(II, Pd(II, Rh(III and Ru(III Complexes with Methylquinolino[3,2-b]benzodiazepine

    Directory of Open Access Journals (Sweden)

    Bennehalli Basavaraju

    2007-01-01

    Full Text Available A series of new complexes formed by the interaction of a new ligand Methylquinolino[3,2-b]benzodiazepine (L with various transition metal ions have been isolated and characterized by elemental analysis and electronic, IR, magnetic moment and conductivity measurements. Thermogravimetric (TG studies of the complexes have been performed in order to establish the mode of their thermal degradation. The thermal degradation was found to proceed in two steps. The kinetics and thermodynamic parameters were computed from the thermal decomposition data.

  19. Effect of molar ratio on thermal mass loss kinetics of poly({epsilon}-caprolactone-b-propylene adipate) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Nanaki, Stavroula G. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Macedonia (Greece); Chrissafis, K. [Solid State Physics Section, Physics Department, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Macedonia (Greece); Bikiaris, Dimitrios N., E-mail: dbic@chem.auth.gr [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Macedonia (Greece)

    2011-04-20

    Research highlights: {yields} Thermal decomposition behaviour of PCL-b-PPAd block copolymers was estimated. {yields} The prepared copolymers have higher thermal stability than neat polymers. {yields} In copolymers the evaporation of PPAd short blocks and formed {epsilon}-CL is delayed. {yields} This is because copolymers degrade with a different mechanism than neat polymers. - Abstract: Poly({epsilon}-caprolactone-b-propylene adipate) copolymers were synthesized using a combination of polycondensation and ring opening polymerisation. GPC was used for molecular weight determination. {sup 1}H-NMR and {sup 13}C-NMR spectroscopy was also used for copolymer characterization and composition, which was found similar to the feeding ratio. DSC study was used in order to define T{sub g}, T{sub m} and {Delta}H{sub m} values of neat polymers and copolymers. Mass loss upon heating kinetics of neat polymers and their copolymers were studied by using thermogravimetric analysis (TGA). It was found that copolymers have almost the same thermal stability as PCL, which is the most stable part. The influence of PPAd in copolymers can mainly be seen at the beginning of mass loss where a small overlapped peak can be observed. The kinetic parameters of mass loss upon heating of all polyesters were calculated while the activation energies were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Mass loss upon heating was found to be described by two mechanisms that follow each other. The first mechanism is attributed to a small mass loss, while the second mechanism is attributed to the main mass loss as in autocatalysis n{sup th}-order (reaction model Cn) or n{sup th} order (reaction model Fn).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-30

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

  1. Salt effect on sensitized photooxidations. A kinetic approch to environmental decomposition of marine contaminants

    Directory of Open Access Journals (Sweden)

    María I. Gutiérrez

    1998-09-01

    Full Text Available The salt effect on the kinetics of singlet molecular oxygen [O2(1Δg]-mediated photooxidations of sea water contaminants was investigated. Two families of photooxidizable compounds were employed in the study: anthracene derivatives and phenols. The presence of salt (NaCl in H2O and LiCl in MeCN, in both cases in the range 0-0.45 M produces changes in the photooxidation rate. For solvent-polarity-dependent reactions, this behavior can be predicted, by knowing the solvent-polarity dependence of the rate constant for chemical reaction of the substrates with O2(1Δ g in non-saline solutions (kr. For the cases of photooxidations possessing solvent-polarity-independent or scantily-dependent kr values, the photooxidation rates decrease as the salt content in the solution increases, mainly due to a predominance of the physical quenching pathway. In addition, the quantum yield for O2(1 Δg generation (ΦΔ was determined in a series of saline solutions, in the range of 0-0.45 M in water and MeCN solutions, in the presence of NaCl and LiCl respectively. The Δ values are independent, within the experimental error on the salt content.

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

    Energy Technology Data Exchange (ETDEWEB)

    Flament, T.A.

    1998-02-26

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

  3. Adsorption Behavior, Thermodynamics, and Kinetics of the Methanol Decomposition Reaction on defective graphene-supported Pt13

    Science.gov (United States)

    Gasper, Raymond; Ramasubramaniam, Ashwin

    Defective graphene has been shown experimentally to be an excellent support for transition-metal electrocatalysts in direct methanol fuel cells. Prior computational modeling has shown that the improved catalytic activity of graphene-supported metal clusters is in part due to increased resistance to catalyst sintering and CO poisoning, but the increased reaction rate for the methanol decomposition reaction (MDR) is not yet fully explained. Using DFT, we investigate the adsorption of MDR intermediates and reaction thermodynamics on defective graphene-supported Pt13 nanoclusters with realistic, low-symmetry morphologies. We find that the support-induced shifts in Pt13 electronic structure correlate well with a rigid shift in adsorption of MDR intermediates, and that adsorption energy scaling relationships perform well on the low-symmetry surface. We investigate the reaction kinetics and thermodynamics, including testing the effectiveness of scaling relationships for predicting reaction barriers on the nanoclusters. Using these fundamental data, we perform microkinetic modeling to quantify the effect of the support on the MDR, and to understand how the support influences surface coverages, CO poisoning, and the relationships between reaction pathways. Funded by U.S. Department of Energy under Award Number DE-SC0010610. Computational resources were provided by National Energy Research Scientific Computing Center.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-09

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

  5. 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.

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

    Directory of Open Access Journals (Sweden)

    R. C. Sullivan

    2004-01-01

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

  7. Synthesis and thermal degradation Kinetics of D - (+ - galactose containing polymers

    Directory of Open Access Journals (Sweden)

    Fehmi Saltan

    2013-01-01

    Full Text Available In this study, it is investigated the synthesis and characterizations of polymerizable vinyl sugars. Carbohydrate containing polymers were synthesized via free radical polymerization. Thermal behavior of polymer derivatives was analyzed by using DSC and TG. Molecular weight dispersion of polymer derivatives was also analyzed with GPC. Molecular structures were analyzed by FT-IR and 1H-NMR spectrophotometer. We found that molecular weight of copolymers could effect to the thermal stability. According to TG data related to the copolymers, molecular weight of polymers increased while the thermal stability decreased. Thermogravimetric analysis of polymers also investigated. The apparent activation energies for thermal degradation of carbohydrate containing polymers were obtained by integral methods (Flynn - Wall - Ozawa, Kissinger - Akahira - Sunose, and Tang.

  8. Linear correlation between thermal stability and folding kinetics of lysozyme.

    Science.gov (United States)

    Cao, Aoneng; Wang, Gang; Tang, Youqi; Lai, Luhua

    2002-03-08

    We have studied the refolding and thermal denaturation of hen egg white lysozyme in a wide range of pH values (from 1.5 to 9.4) using stopped-flow circular dichroism (CD) and differential scanning calorimetry (DSC). A linear correlation was found between the thermal denaturation temperature (T(m)) and the logarithm of the refolding rate of the slow folding phase of hen egg white lysozyme (lnk(2)).

  9. Improving Neutron Kinetics and Thermal Hydraulics coupled tools for BEPU calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pericas, R.; Reventós, F.; Batet, Il.

    2015-07-01

    The BEPU methodology is capable of providing a solution in terms of increasing the nuclear power production without compromising the safety margins. This study presents different improvements performed using tools available at UPC in the field of Neutron Kinetics and Thermal Hydraulics coupled systems. The paper describes a comparison between the BEPU methodology and the Conservative Bounding methodology within the framework of the Neutron Kinetics and Thermal Hydraulics coupled systems. To perform such comparison the following tools have been selected: TRACE for thermal-hydraulic system calculations, PARCS for reactor kinetics core simulator code. A Main Steam Line Break (MSLB) in a Pressurized Water Reactor (PWR) is the selected simulated transient to show the improvements performed. (Author)

  10. Detection of stealthy outliers in thermal-kinetics modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kumpinsky, Enio [Global Technology, Ashland Inc., PO Box 2219, Columbus, OH 43216 (United States)], E-mail: ekumpinsky@ashland.com

    2008-11-20

    A method is presented to uncover outliers in data from small-scale process-safety studies. Points along an adiabatic runaway reaction, especially at the onset and conclusion of the experiment, may be vaguely jittery and difficult to recognize as outliers. Even though they fit well visually, their stealthy misalignment may have a profound impact on the estimate of kinetic parameters, such as reaction order, pre-exponential factor and activation energy. The proposed technique combines temperature and its time derivatives to magnify the effect of hidden outliers. Once identified, these points can be excluded from regression, in order to generate kinetic parameters with minimal distortions. This method is also suited to recognize autocatalysis.

  11. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Mohamad Irfan Fathurrohman

    2015-07-01

    Full Text Available The vulcanization kinetics of Ethylene-propylene diene monomer (EPDM rubber thermal insulation was studied by using rheometer under isothermal condition at different temperatures. The rheometry analysis was used to determining the cure kinetic parameters and predicting the cure time of EPDM thermal insulation. The experimental results revealed that the curing curves of EPDM thermal insulation were marching and the optimum curing time decreased with increasing the temperature. The kinetic parameters were determined from the autocatalytic model showed close fitting with the experimental results, indicating suitability of autocatalytic model in characterizing the cure kinetics. The activation energy was determined from the autocatalytic model is 46.3661 kJ mol-1. The cure time were predicted from autocatalytic model and the obtained kinetic parameter by using the relationship among degree of conversion, cure temperature, and cure time. The predictions of cure time provide information for the actual curing characteristic of EPDM thermal insulation. The mechanical properties of EPDM thermal insulation with different vulcanization temperatures showed the same hardness, tensile strength and modulus at 300%, except at temperature 70 °C, while the elongation at breaking point decreased with increasing temperature of vulcanization. © 2015 BCREC UNDIP. All rights reservedReceived: 8th April 2014; Revised: 7th January 2015; Accepted: 16th January 2015How to Cite: Fathurrohman, M.I., Maspanger, D.R., Sutrisno, S. (2015. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation. Bulletin of Chemi-cal Reaction Engineering & Catalysis, 10 (2, 104-110. (doi:10.9767/bcrec.10.2.6682.104-110Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.6682.104-110 

  12. Heavy metal evaporation kinetics in thermal waste treatment processes

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Ch.; Stucki, S.; Schuler, A.J. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    To investigate the evaporation kinetics of heavy metals, experiments were performed by conventional thermogravimetry and a new method using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The new method allows online measurements in time intervals that are typically below one minute. The evaporation of Cd, Cu, Pb, and Zn from synthetic mixtures and filter ashes from municipal solid waste incineration (MSWI) was of major interest. (author) 2 figs., 4 refs.

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

    Science.gov (United States)

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

    2017-10-01

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

  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. Synthesis, spectral characterization and study of thermal behavior kinetics by thermogravimetric analysis of metal complexes derived from salicylaldehyde and alkylamine

    Science.gov (United States)

    Bouzerafa, Brahim; Aggoun, Djouhra; Ouennoughi, Yasmina; Ourari, Ali; Ruiz-Rosas, Ramiro; Morallon, Emilia; Mubarak, Mohammad S.

    2017-08-01

    Cobalt(III)- and copper(II)-Schiff base complexes have been prepared by reaction of the bidentate Schiff base ligand (HL: 2-(4-methoxyphenyl)-1-iminosalicylidenethane) with cobalt(II) and copper(II) chlorides. Structures of the synthesized complexes have been characterized by various physicochemical techniques, such as IR and UV-Vis spectroscopy, mass spectrometry, thermogravimetric analysis (TG/DTG), and by elemental analysis. Additionally, the redox behavior of the cobalt(III) and copper(II) complexes has been examined by cyclic voltammetry at a glassy carbon electrode in DMF solutions. Thermogravimetric analysis has been employed to evaluate the thermal stability of the prepared complexes CoIII(L)3·1/2H2O, CuII(L)2, in addition to the previously synthesized HL and NiII(L)2. Furthermore, activation energies of the thermal decomposition were calculated using Kissinger, Ozawa and Coats-Redfern methods. The calculated activation energies were also useful to evaluate kinetic and thermodynamic parameters of the ligand and the corresponding metal complexes including ΔS, ΔH and ΔG. Calculated activation energies follow the order: Ea(NiII(L)2) > Ea(CuII(L)2) > Ea(CoIII(L)3·1/2H2O).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-10-25

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

  17. modelling of thermal degradation kinetics of ascorbic acid in ...

    African Journals Online (AJOL)

    Administrator

    dried, cooked, canned and frozen fruit and vegetables are a ... Samuel E. Agarry, Biochemical Engineering Research Laboratory, Department of Chemical .... Table 1: Rate Constants for Thermal Degradation of Ascorbic Acid in Potato and Pawpaw at Various. Temperatures. Food Material. T oC. ) (min. 10. 1. 3. −. −. xK. T.

  18. Synthesis, crystal structure and catalytic effect on thermal decomposition of RDX and AP: An energetic coordination polymer [Pb{sub 2}(C{sub 5}H{sub 3}N{sub 5}O{sub 5}){sub 2}(NMP)·NMP]{sub n}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jin-jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Liu, Zu-Liang, E-mail: liuzl@mail.njust.edu.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Cheng, Jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Fang, Dong, E-mail: fangdong106@163.com [Yancheng Teachers College, Yancheng 224002 (China)

    2013-04-15

    An energetic lead(II) coordination polymer based on the ligand ANPyO has been synthesized and its crystal structure has been got. The polymer was characterized by FT-IR spectroscopy, elemental analysis, DSC and TG-DTG technologies. Thermal analysis shows that there are one endothermic process and two exothermic decomposition stages in the temperature range of 50–600 °C with final residues 57.09%. The non-isothermal kinetic has also been studied on the main exothermic decomposition using the Kissinger's and Ozawa–Doyle's methods, the apparent activation energy is calculated as 195.2 KJ/mol. Furthermore, DSC measurements show that the polymer has significant catalytic effect on the thermal decomposition of ammonium perchlorate. - Graphical abstract: An energetic lead(II) coordination polymer of ANPyO has been synthesized, structurally characterized and properties tested. Highlights: ► We have synthesized and characterized an energetic lead(II) coordination polymer. ► We have measured its molecular structure and thermal decomposition. ► It has significant catalytic effect on thermal decomposition of AP.

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

    Directory of Open Access Journals (Sweden)

    Crespi Marisa S.

    1999-01-01

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

  20. 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...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  2. CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    A. NOZAD

    2011-06-01

    Full Text Available The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was bulk crystallization for base glass and the sample with addition of Li2O. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of Li2O was changed to the range of 317-322 KJ/mol.

  3. Thermal inactivation kinetics of hepatitis A virus in spinach.

    Science.gov (United States)

    Bozkurt, Hayriye; Ye, Xiaofei; Harte, Federico; D'Souza, Doris H; Davidson, P Michael

    2015-01-16

    Leafy vegetables have been recognized as important vehicles for the transmission of foodborne viral pathogens. To control hepatitis A viral foodborne illness outbreaks associated with mildly heated (e.g., blanched) leafy vegetables such as spinach, generation of adequate thermal processes is important both for consumers and the food industry. Therefore, the objectives of this study were to determine the thermal inactivation behavior of hepatitis A virus (HAV) in spinach, and provide insights on HAV inactivation in spinach for future studies and industrial applications. The D-values calculated from the first-order model (50-72 °C) ranged from 34.40 ± 4.08 to 0.91 ± 0.12 min with a z-value of 13.92 ± 0.87 °C. The calculated activation energy value was 162 ± 11 kJ/mol. Using the information generated in the present study and the thermal parameters of industrial blanching conditions for spinach as a basis (100 °C for 120-180 s), the blanching of spinach in water at 100 °C for 120-180 s under atmospheric conditions will provide greater than 6 log reduction of HAV. The results of this study may be useful to the frozen food industry in designing blanching conditions for spinach to inactivate or control hepatitis A virus outbreaks. Copyright © 2014. Published by Elsevier B.V.

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

    Directory of Open Access Journals (Sweden)

    Quang Hung Trinh

    2015-04-01

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

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

    Science.gov (United States)

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

    2013-12-15

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

  6. Studies on the thermal decomposition kinetics of LiPF 6 and LiBC 4 ...

    Indian Academy of Sciences (India)

    Author Affiliations. Li Shi-You1 2 Ma Pei-Hua1 Cui Xiao-Ling1 Ren Qi-Du1 2 Li Fa-Qiang1. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810 008, China; Graduate School of the Chinese Academy of Sciences, Beijing 100 039, China ...

  7. Kinetic and thermal characterization of the hydrolysis of polysuccinimide

    Energy Technology Data Exchange (ETDEWEB)

    Mosig, J.; Gooding, C.H.; Wheeler, A.P. [Clemson Univ., SC (United States)

    1997-06-01

    Hundreds of millions of pounds of anionic polymers, particularly poly(acrylate) and its derivatives, are used annually as dispersants and antiscalants in water-treatment formulations and detergents, and much of this is released into environmental waters. Though these polymers are apparently not toxic, neither are they especially biodegradable. The kinetics of the base hydrolysis of polysuccinimide in an aqueous slurry were studied with temperatures ranging from 31 to 72 C and pH`s from 8.0 to 10.5. At the higher temperatures and lower pH values, the results are described adequately by a shrinking core model that is first order with respect to hydroxyl concentration and particle surface area. Temperature effects were modeled with an Arrhenius equation, which indicates an activation energy of 35 kJ/mol. In separate experiments, the heat of reaction was determined to be 38.5 kJ/mol.

  8. Coupling Chemical Kinetics and Flashes in Reactive, Thermal and Compositional Reservoir Simulation

    DEFF Research Database (Denmark)

    Kristensen, Morten Rode; Gerritsen, Margot G.; Thomsen, Per Grove

    2007-01-01

    Phase changes are known to cause convergence problems for integration of stiff kinetics in thermal and compositional reservoir simulations. We propose an algorithm for detection and location of phase changes based on discrete event system theory. The algorithm provides a robust way for handling...

  9. Comparative study of thermal inactivation kinetics of Salmonella spp. in peanut butter and peanut butter spread

    Science.gov (United States)

    Peanut butter has been implicated in multi-state outbreaks of salmonellosis in recent years. Studies have shown that Salmonella exhibited increased thermal resistance in peanut butter. However, little is known about the effect of product formulation on the kinetics of survival of Salmonella during...

  10. Alkaline assisted thermal oil recovery: Kinetic and displacement studies

    Energy Technology Data Exchange (ETDEWEB)

    Saneie, S.; Yortsos, Y.C.

    1993-06-01

    This report deals with two major issues of chemical assisted flooding - the interaction of caustic, one of the proposed additives to steam flood, with the reservoir rock, and the displacement of oil by a chemical flood at elevated temperatures. A mathematical model simulating the kinetics of silica dissolution and hydroxyl ion consumption in a typical alkaline flooding environment is first developed. The model is based on the premise that dissolution occurs via hydrolysis of active sites through the formation of an intermediate complex, which is in equilibrium with the silicic acid in solution. Both static (batch) and dynamic (core flood) processes are simulated to examine the sensitivity of caustic consumption and silica dissolution to process parameters, and to determine rates of propagation of pH values. The model presented provides a quantitative description of the quartz-alkali interaction in terms of pH, salinity, ion exchange properties, temperature and contact time, which are of significant importance in the design of soluble silicate flooding processes. The modeling of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is next presented. The model is also applicable to the hot alkaline flooding under conditions of negligible adsorption of the generated anionic surfactant and of hydroxide adsorption being Langmuirian. The theory of generalized simple waves (coherence ) is used to develop solutions for the temperature, concentration, and oil saturation profiles, as well as the oil recovery curves. It is shown that, for Langmuir adsorption kinetics, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value, and in the unheated region if its concentration exceeds this critical value. Results for a chemical slug injection in a tertiary recovery process indicate recovery performance is maximized when chemical resides in the heated region of the reservior.

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

    Science.gov (United States)

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

    2013-05-09

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

  12. Kinetics of Thermal Denaturation and Aggregation of Bovine Serum Albumin.

    Directory of Open Access Journals (Sweden)

    Vera A Borzova

    Full Text Available Thermal aggregation of bovine serum albumin (BSA has been studied using dynamic light scattering, asymmetric flow field-flow fractionation and analytical ultracentrifugation. The studies were carried out at fixed temperatures (60°C, 65°C, 70°C and 80°C in 0.1 M phosphate buffer, pH 7.0, at BSA concentration of 1 mg/ml. Thermal denaturation of the protein was studied by differential scanning calorimetry. Analysis of the experimental data shows that at 65°C the stage of protein unfolding and individual stages of protein aggregation are markedly separated in time. This circumstance allowed us to propose the following mechanism of thermal aggregation of BSA. Protein unfolding results in the formation of two forms of the non-native protein with different propensity to aggregation. One of the forms (highly reactive unfolded form, Uhr is characterized by a high rate of aggregation. Aggregation of Uhr leads to the formation of primary aggregates with the hydrodynamic radius (Rh,1 of 10.3 nm. The second form (low reactive unfolded form, Ulr participates in the aggregation process by its attachment to the primary aggregates produced by the Uhr form and possesses ability for self-aggregation with formation of stable small-sized aggregates (Ast. At complete exhaustion of Ulr, secondary aggregates with the hydrodynamic radius (Rh,2 of 12.8 nm are formed. At 60°C the rates of unfolding and aggregation are commensurate, at 70°C the rates of formation of the primary and secondary aggregates are commensurate, at 80°C the registration of the initial stages of aggregation is complicated by formation of large-sized aggregates.

  13. Kinetics of Thermal Denaturation and Aggregation of Bovine Serum Albumin

    Science.gov (United States)

    Borzova, Vera A.; Markossian, Kira A.; Chebotareva, Natalia A.; Kleymenov, Sergey Yu.; Poliansky, Nikolay B.; Muranov, Konstantin O.; Stein-Margolina, Vita A.; Shubin, Vladimir V.; Markov, Denis I.; Kurganov, Boris I.

    2016-01-01

    Thermal aggregation of bovine serum albumin (BSA) has been studied using dynamic light scattering, asymmetric flow field-flow fractionation and analytical ultracentrifugation. The studies were carried out at fixed temperatures (60°C, 65°C, 70°C and 80°C) in 0.1 M phosphate buffer, pH 7.0, at BSA concentration of 1 mg/ml. Thermal denaturation of the protein was studied by differential scanning calorimetry. Analysis of the experimental data shows that at 65°C the stage of protein unfolding and individual stages of protein aggregation are markedly separated in time. This circumstance allowed us to propose the following mechanism of thermal aggregation of BSA. Protein unfolding results in the formation of two forms of the non-native protein with different propensity to aggregation. One of the forms (highly reactive unfolded form, Uhr) is characterized by a high rate of aggregation. Aggregation of Uhr leads to the formation of primary aggregates with the hydrodynamic radius (Rh,1) of 10.3 nm. The second form (low reactive unfolded form, Ulr) participates in the aggregation process by its attachment to the primary aggregates produced by the Uhr form and possesses ability for self-aggregation with formation of stable small-sized aggregates (Ast). At complete exhaustion of Ulr, secondary aggregates with the hydrodynamic radius (Rh,2) of 12.8 nm are formed. At 60°C the rates of unfolding and aggregation are commensurate, at 70°C the rates of formation of the primary and secondary aggregates are commensurate, at 80°C the registration of the initial stages of aggregation is complicated by formation of large-sized aggregates. PMID:27101281

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

    Science.gov (United States)

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

    2013-01-23

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

  15. Thermal degradation behaviors of polyethylene and polypropylene. Part I: Pyrolysis kinetics and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Aboulkas, A.; El Harfi, K. [Laboratoire de Recherche sur la Reactivites des Materiaux et l' Optimisation des Procedes & lt; & lt; REMATOP& gt; & gt; , Departement de chimie, Faculte des Sciences Semlalia, Universite Cadi Ayyad, BP 2390, 40001 Marrakech (Morocco); Laboratoire Interdisciplinaire de Recherche en Sciences et Techniques, Faculte polydisciplinaire de Beni-Mellal, Universite Sultan Moulay Slimane, BP 592, 23000 Beni-Mellal (Morocco); El Bouadili, A. [Laboratoire Interdisciplinaire de Recherche en Sciences et Techniques, Faculte polydisciplinaire de Beni-Mellal, Universite Sultan Moulay Slimane, BP 592, 23000 Beni-Mellal (Morocco)

    2010-07-15

    Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, the activation energy and the reaction model of the pyrolysis of high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) have been estimated from non-isothermal kinetic results. Firstly, the activation energy values obtained by Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa isoconversional methods, are 238-247 kJ/mol for HDPE, 215-221 kJ/mol for LDPE and 179-188 kJ/mol for PP. Secondly, the appropriate conversion model of the process was determined by Coats-Redfern and Criado methods. The pyrolysis reaction models of HDPE and LDPE are accounted for by ''Contracting Sphere'' model, whereas that of PP by ''Contracting Cylinder'' model. (author)

  16. Kinetic simulation of complex decomposition as a tool for the ion chromatographic determination of elemental speciation of less inert metal ions.

    Science.gov (United States)

    Winter, Christian; Seubert, Andreas

    2016-01-15

    Species decomposition is an often occurring artefact during the chromatographic determination of elemental speciation. The decomposition follows a simple path to lower coordinated compounds. Therefore a simulation is developed for those decomposition reactions. The simulation separates the isochronal processes of the separation itself and the ongoing reaction and delivers thermodynamic and kinetic information about the species present in the original sample. This shifts the boundaries of separation based elemental speciation to less inert metal ions which are typically not analyzable by this approach. The less inert gallium monooxalato complex [GaOx](+) is used as example for testing the simulation software as this complex decomposes only to Ga(3+) and both species are retained on cation exchange columns. We extracted thermodynamic and kinetic information from flow rate experiments by the analysis of the peak areas in the chromatogram. The results show that some of our assumptions such as the irreversibility under the applied chromatographic conditions are not ultimately true, but good accordance of simulation and measured data was achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-15

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

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

    Directory of Open Access Journals (Sweden)

    Aliakbar Dehno Khalaji

    2015-06-01

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

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

    Science.gov (United States)

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

    2003-10-01

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

  20. Thermal Degradation Kinetics of Sugarcane Bagasse and Soft Wood Cellulose

    Directory of Open Access Journals (Sweden)

    Samson M. Mohomane

    2017-10-01

    Full Text Available The properties of untreated sugar cane bagasse (SCB and soft wood (SW and their respective celluloses were investigated. The celluloses indicated improved crystallinity index values and decreased concentration of lignin and hemicellulose compared to their untreated counterparts. Three degradation models, Kissinger-Akahira-Sunose (KAS, Flynn-Wall-Ozawa (OFW, and Kissinger (KGR methods were employed to determine apparent activation energy values. Generally, the thermal degradation processes of both sugarcane bagasse and soft wood included dehydration, degradation of hemicellulose and cellulose, whereas the lignin degraded from the degradation temperature of hemicellulose to the end of the cellulose. The apparent activation energy values obtained from the OFW and KAS models vary with the degree of conversion, and showed similar trends. The activation energies obtained by KGR were relatively lower than those obtained from the KAS and OFW methods.

  1. Thermal behaviour and kinetics of alga Polysiphonia elongata biomass during pyrolysis.

    Science.gov (United States)

    Ceylan, Selim; Topcu, Yıldıray; Ceylan, Zeynep

    2014-11-01

    The pyrolysis characteristics and kinetics of Polysiphonia elongata were investigated using a thermogravimetric analyzer. The main decomposition of samples occurred between 225 °C and 485 °C at heating rates of 5-40 °C/min; owing to release of 78-82% of total volatiles. The heating rate effected pyrolysis characteristics such as maximum devolatilization rate and decomposition temperature. However, total volatile matter yield was not significantly affected by heating rate. The activation energy of pyrolysis reaction was calculated by model free Friedman and Kissenger-Akahira-Sunose methods and mean values were 116.23 kJ/mol and 126.48 kJ/mol, respectively. A variance in the activation energy with the proceeding conversions was observed for the models applied, which shows that the pyrolysis process was composed of multi-step kinetics. The Coats-Redfern method was used to determine pre-exponential factor and reaction order. The obtained parameters were used in simulation of pyrolysis process and results were in a good agreement with experimental data. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Decomposition of aspirin in the solid state in the presence of limited amounts of moisture II: Kinetics and salting-in of aspirin in aqueous acetic acid solutions.

    Science.gov (United States)

    Carstensen, J T; Attarchi, F

    1988-04-01

    The solubility of aspirin in saturated solutions of salicylic acid (and vice versa) was studied in 0 to 16 M aqueous solutions of acetic acid. The solubilities, when expressed in molarity, go through a maximum at an acetic acid concentration of approximately 12 M. The temperature dependence of the solubilities is such that the logarithm of the solubility is linear in reciprocal absolute temperature. The calculated enthalpies are of the order of 11 kcal/mol. The kinetics of aspirin decomposition was also studied at the different acetic acid concentrations, and it was found that the second-order hydrolysis rate constant is fairly independent of acetic acid concentration. Aspirin decomposition follows an Arrhenius equation and has an activation energy of 18 kcal/mol.

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

    Directory of Open Access Journals (Sweden)

    Ashfaque H. Bokhari

    2009-01-01

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

  4. The Kinetics of the Trimethoxyboroxine-Induced Thermal Polymerization of Phenyl Glycidyl Ether

    Science.gov (United States)

    Lopata, Eugene S.; Riccitiello, Salvatore R.

    1975-01-01

    The kinetics of the bulk thermal polymerization of phenyl glycidyl ether induced by trimethoxyboroxine were investigated. Infrared absorption spectroscopy and gel permeation chromatography were used to follow the course of polymerization, while proton and boron-2 NMR spectroscopy were used to support the kinetic model developed. The postulated mechanism involves a fast-initiated, non-stationary cationic polymerization with five elementary steps, including spontaneous and monomer transfer as well as a termination reaction. The trimethoxyboroxine was found to be incorporated into the structure of the cured polymer. Tile polymerization was followed at several temperatures and with several ratios of initial concentrations of trimethoxyboroxine to phenyl glycidyl ether.

  5. Applications of sample-controlled thermal analysis (SCTA) to kinetic analysis and synthesis of materials

    OpenAIRE

    Pérez-Maqueda, Luis A.; Criado Luque, J.M.; Sánchez-Jiménez, P.E.; Diánez, M. J.

    2015-01-01

    The advantages of the sample-controlled thermal analysis (SCTA) for both the kinetic analysis of solid-state reactions and the synthesis of materials are reviewed. This method implies an intelligent control of the temperature by the solid-state reaction under study in such a way that the reaction rate as a function of the time fits a profile previously defined by the user. It has been shown that SCTA has important advantages for discriminating the kinetic model of solid-state reactions as com...

  6. The kinetic and solvent deuterium isotope effects in the 4- and 5-positions of the indole ring on the enzymatic decomposition of L-tryptophan.

    Science.gov (United States)

    Winnicka, Elzbieta; Dabrowski, Pawel; Winek, Tomasz; Kanska, Marianna

    2010-06-01

    The kinetic and solvent deuterium isotope effects in the 4- and 5-positions of the indole ring on the enzymatic decomposition of l-tryptophan catalysed by the enzyme TPase (EC. 4.1.99.1) were determined. The isotope effects were investigated by the non-competitive method using [4'-(2)H]-l-tryptophan, which was enriched in deuterium in 70% in the 4-position. The numerical values of isotope effects for 100% enrichment in deuterated label in that position were calculated by approximation. Those same isotope effects were determined for [5'-(2)H]-l-tryptophan fully deuteriated in the 5' -position.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-09

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

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

    Science.gov (United States)

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

    2018-01-01

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

  9. Data on blueberry peroxidase kinetic characterization and stability towards thermal and high pressure processing

    Directory of Open Access Journals (Sweden)

    Netsanet Shiferaw Terefe

    2017-08-01

    Full Text Available The data presented in this article are related to a research article entitled ‘Thermal and high pressure inactivation kinetics of blueberry peroxidase’ (Terefe et al., 2017 [1]. In this article, we report original data on the activity of partially purified blueberry peroxidase at different concentrations of hydrogen peroxide and phenlylenediamine as substrates and the effects of thermal and high pressure processing on the activity of the enzyme. Data on the stability of the enzyme during thermal (at temperatures ranging from 40 to 80 °C and combined thermal-high pressure processing (100–690 MPa, 30–90 °C are included in this report. The data are presented in this format in order to facilitate comparison with data from other researchers and allow statistical analyses and modeling by others in the field.

  10. Effects of magnetic and kinetic helicities on the growth of magnetic fields in laminar and turbulent flows by helical-Fourier decomposition

    CERN Document Server

    Linkmann, Moritz; McKay, Mairi; Berera, Arjun; Biferale, Luca

    2016-01-01

    We present a numerical and analytical study of incompressible homogeneous conducting fluids using a Fourier-helical representation. We analytically study both small- and large-scale dynamo properties, as well as the inverse cascade of magnetic helicity, in the most general minimal subset of interacting velocity and magnetic fields on a closed Fourier triad. We mainly focus on the dependency of magnetic field growth as a function of the distribution of kinetic and magnetic helicities among the three interacting wavenumbers. By combining direct numerical simulations of the full magnetohydrodynamics (MHD) equations with the Fourier-helical decomposition we numerically confirm that in the kinematic dynamo regime the system develops a large-scale magnetic helicity with opposite sign compared to the small-scale kinetic helicity, a sort of triad-by-triad $\\alpha$-effect in Fourier space. Concerning the small-scale perturbations, we predict theoretically and confirm numerically that the largest instability is achived...

  11. Numerical simulation of kinetic demixing and decomposition in a LaCoO3-δ oxygen membrane under an oxygen potential gradient

    DEFF Research Database (Denmark)

    Ta, Na; Chen, Ming; Zhang, Lijun

    2018-01-01

    A composition- and temperature-dependent mobility database of all ionic species in the LaCoO3-δ phase was developed and combined with a La-Co-O thermodynamic database to simulate kinetic demixing and partial decomposition in LaCoO3-δ oxygen membranes operated under a 0.0001/0.21 bar oxygen partial...... pressure difference at 1073 K for 1 year. Formation of La2O3, Co3O4 and CoO phases across the membrane is predicted. The kinetic demixing process can be divided into two stages, namely, establishment of the oxygen potential gradient (fast) and demixing of the cations (slow); the former is controlled...

  12. 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.

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

    Science.gov (United States)

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

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

  14. MCNP5 study on kinetics parameters of coupled fast-thermal system HERBE

    Directory of Open Access Journals (Sweden)

    Pešić Milan P.

    2011-01-01

    Full Text Available New validation of the well-known Monte Carlo code MCNP5 against measured criticality and kinetics data for the coupled fast-thermal HERBE System at the Reactor B critical assembly is shown in this paper. Results of earlier calculations of these criticality and kinetics parameters, done by combination of transport and diffusion codes using two-dimension geometry model are compared to results of new calculations carried out by the MCNP5 code in three-dimension geometry. Satisfactory agreements in comparison of new results with experimental data, in spite complex heterogeneous composition of the HERBE core, are achieved confirming that MCNP5 code could apply successfully to study on HERBE kinetics parameters after uncertainties in impurities in material compositions and positions of fuel elements in fast zone were removed.

  15. Thermal Stability and Kinetic Study of Fluvoxamine Stability in Binary Samples with Lactose

    Directory of Open Access Journals (Sweden)

    Faranak Ghaderi

    2017-04-01

    Full Text Available Purpose: In the present study the incompatibility of FLM (fluvoxamine with lactose in solid state mixtures was investigated. The compatibility was evaluated using different physicochemical methods such as differential scanning calorimetry (DSC, Fourier-transform infrared (FTIR spectroscopy and mass spectrometry. Methods: Non-Isothermally stressed physical mixtures were used to calculate the solid–state kinetic parameters. Different thermal models such as Friedman, Flynn–Wall–Ozawa (FWO and Kissinger–Akahira–Sunose (KAS were used for the characterization of the drug-excipient interaction. Results: Overall, the incompatibility of FLM with lactose as a reducing carbohydrate was successfully evaluated and the activation energy of this interaction was calculated. Conclusion: In this research the lactose and FLM Maillard interaction was proved using physicochemical techniques including DSC and FTIR. It was shown that DSC- based kinetic analysis provides fast and versatile kinetic comparison of Arrhenius activation energies for different pharmaceutical samples.

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

    Science.gov (United States)

    Wu, Qiong; Zhu, Weihua; Xiao, Heming

    2014-10-21

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

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

    Directory of Open Access Journals (Sweden)

    Ferreira Odair P.

    2006-01-01

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

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

    Science.gov (United States)

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

    2017-10-18

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

  19. 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.

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

    Science.gov (United States)

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

    2017-03-01

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

  1. Evaluation of the integral methods for the kinetic study of thermally stimulated processes in polymer science

    OpenAIRE

    Pérez-Maqueda, Luis A.; Sánchez-Jiménez, P.E.; Criado, J.M.

    2005-01-01

    This paper reports on the accuracy of the integral methods used for the kinetic analysis of degradation and crystallization of polymers. Integral methods are preferred by many authors over the differential ones because often the experimental data obtained, such as thermal degradation studied by thermogravimetry, are integral and the differentiation of the integral data usually produces an unwilling increase of the noise. A problem of the integral methods is the fact that Arrhenius integral fu...

  2. Thermal Stability and Kinetic Study of Fluvoxamine Stability in Binary Samples with Lactose

    OpenAIRE

    Faranak Ghaderi; Mahboob Nemati; Mohammad Reza Siahi-Shadbad; Hadi Valizadeh; Farnaz Monajjemzadeh

    2017-01-01

    Purpose: In the present study the incompatibility of FLM (fluvoxamine) with lactose in solid state mixtures was investigated. The compatibility was evaluated using different physicochemical methods such as differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy and mass spectrometry. Methods: Non-Isothermally stressed physical mixtures were used to calculate the solid–state kinetic parameters. Different thermal models such as Friedman, Flynn–Wall–Ozawa (FWO...

  3. Synthesis, structural investigation and kinetic studies of uranyl (VI ...

    Indian Academy of Sciences (India)

    Uranyl schiff base complexes; kinetic study; X-ray crystallography; kinetics of thermal decomposition; cyclic voltammetry. ... Chemistry Department, College of Sciences, Shiraz University, Shiraz 71454, I. R. Iran; Institute of Physics ASCR, v.v.i, Na Slovance 2, 182 21 Praha, Czech Republic; Department of Chemistry, Faculty ...

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

    Directory of Open Access Journals (Sweden)

    Agustin Bueno-López

    2012-09-01

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

  5. Numerical simulations of subcritical reactor kinetics in thermal hydraulic transient phases

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, J.; Park, W. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A subcritical reactor driven by a linear proton accelerator has been considered as a nuclear waste incinerator at Korea Atomic Energy Research Institute (KAERI). Since the multiplication factor of a subcritical reactor is less than unity, to compensate exponentially decreasing fission neutrons, external neutrons form spallation reactions are essentially required for operating the reactor in its steady state. Furthermore, the profile of accelerator beam currents is very important in controlling a subcritical reactor, because the reactor power varies in accordance to the profile of external neutrons. We have developed a code system to find numerical solutions of reactor kinetics equations, which are the simplest dynamic model for controlling reactors. In a due course of our previous numerical study of point kinetics equations for critical reactors, however, we learned that the same code system can be used in studying dynamic behavior of the subcritical reactor. Our major motivation of this paper is to investigate responses of subcritical reactors for small changes in thermal hydraulic parameters. Building a thermal hydraulic model for the subcritical reactor dynamics, we performed numerical simulations for dynamic responses of the reactor based on point kinetics equations with a source term. Linearizing a set of coupled differential equations for reactor responses, we focus our research interest on dynamic responses of the reactor to variations of the thermal hydraulic parameters in transient phases. 5 refs., 8 figs. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  7. Study of Curing Kinetics and Thermal Degradation of UV Curable Epoxy Acrylate Resin

    Directory of Open Access Journals (Sweden)

    Amrita Sharma

    2008-01-01

    Full Text Available Blends of epoxy acrylate resins (acid values 3, 6.5 & 10 mg KOH/gm Solid with monofunctional monomers (ethoxylated phenol monoacrylate were prepared by physical mixing, having weight ratio 50:50. These blends were cured by using UV radiations in presence of photo initiator (Darocure 1173. The thermal degradation kinetics of these resin blends were studied, using thermo gravimetric analysis in nitrogen atmosphere at a heating rate of 10°C/min. by applying Coats-Red fern equation. According to the analysis, all the coating films degrade in two steps. In the first step of degradation kinetics, R2M follows 1.75 order (n=1.75 and all other coating films follow second order (n=2 kinetics. In second step, R2M & R3M follow half order (n=0.5 kinetics and R1M follow first order (n=1 degradation kinetics. Order of the reaction is obtained on the basis of best fit analysis, and all the parameters were confirmed by regression analysis. From the reaction order, value of activation energy (E and pre exponential factor (Z were calculated by the slop and intercept of the plot between X and Y, respectively.

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

    OpenAIRE

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2011-11-24

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-04-01

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

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

    Science.gov (United States)

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

    2013-01-15

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

  12. 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.

  13. Gas-Kinetic Navier-Stokes Solver for Hypersonic Flows in Thermal and Chemical Non-Equilibrium Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project proposes to develop a gas-kinetic Navier-Stokes solver for simulation of hypersonic flows in thermal and chemical non-equilibrium. The...

  14. The determination of kinetic parameters of LiF : Mg,Ti from thermal decaying curves of optical absorption bands

    CERN Document Server

    Yazici, A N

    2003-01-01

    In this paper, the thermal bleaching curves (TBCs) of specific optical absorption bands of LiF : Mg,Ti were measured as a function of temperature. The TBCs obtained were analysed to extract the kinetic parameters (the thermal activation energy (E) and the frequency factor (s)) of some TL glow peaks of LiF : Mg,Ti on the basis of the developed first-order kinetic model over a specified temperature region.

  15. Complex kinetics and residual structure in the thermal unfolding of yeast triosephosphate isomerase.

    Science.gov (United States)

    Labastida-Polito, Ariana; Garza-Ramos, Georgina; Camarillo-Cadena, Menandro; Zubillaga, Rafael A; Hernández-Arana, Andrés

    2015-09-03

    Saccharomyces cerevisiae triosephosphate isomerase (yTIM) is a dimeric protein that shows noncoincident unfolding and refolding transitions (hysteresis) in temperature scans, a phenomenon indicative of the slow forward and backward reactions of the native-unfolded process. Thermal unfolding scans suggest that no stable intermediates appear in the unfolding of yTIM. However, reported evidence points to the presence of residual structure in the denatured monomer at high temperature. Thermally denatured yTIM showed a clear trend towards the formation of aggregation-prone, β-strand-like residual structure when pH decreased from 8.0 to 6.0, even though thermal unfolding profiles retained a simple monophasic appearance regardless of pH. However, kinetic studies performed over a relatively wide temperature range revealed a complex unfolding mechanism comprising up to three observable phases, with largely different time constants, each accompanied by changes in secondary structure. Besides, a simple sequential mechanism is unlikely to explain the observed variation of amplitudes and rate constants with temperature. This kinetic complexity is, however, not linked to the appearance of residual structure. Furthermore, the rate constant for the main unfolding phase shows small, rather unvarying values in the pH region where denatured yTIM gradually acquires a β-strand-like conformation. It appears, therefore, that the residual structure has no influence on the kinetic stability of the native protein. However, the presence of residual structure is clearly associated with increased irreversibility. The slow temperature-induced unfolding of yeast TIM shows three kinetic phases. Rather than a simple sequential pathway, a complex mechanism involving off-pathway intermediates or even parallel pathways may be operating. β-strand-type residual structure, which appears below pH 8.0, is likely to be associated with increased irreversible aggregation of the unfolded protein. However

  16. Kinetic Monte Carlo study on the evolution of silicon surface roughness under hydrogen thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gang; Wang, Yu; Wang, Junzhuan; Pan, Lijia; Yu, Linwei; Zheng, Youdou; Shi, Yi, E-mail: yshi@nju.edu.cn

    2017-08-31

    Highlights: • The KMC method is adopted to investigate the relationships between surface evolution and hydrogen thermal treatment conditions. • The reduction in surface roughness is divided into two stages at relatively low temperatures, both exhibiting exponential dependence on the time. • The optimized surface structure can be obtained by precisely adjusting thermal treatment temperatures and hydrogen pressures. - Abstract: The evolution of a two-dimensional silicon surface under hydrogen thermal treatment is studied by kinetic Monte Carlo simulations, focusing on the dependence of the migration behaviors of surface atoms on both the temperature and hydrogen pressure. We adopt different activation energies to analyze the influence of hydrogen pressure on the evolution of surface morphology at high temperatures. The reduction in surface roughness is divided into two stages, both exhibiting exponential dependence on the equilibrium time. Our results indicate that a high hydrogen pressure is conducive to obtaining optimized surfaces, as a strategy in the applications of three-dimensional devices.

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

    DEFF Research Database (Denmark)

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

    1985-01-01

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

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

    Science.gov (United States)

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

    2015-08-15

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

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

    Science.gov (United States)

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

    2011-10-01

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

  20. Thermal inactivation kinetics of proteases and polyphenoloxidase in brown shrimp (Crangon crangon).

    Science.gov (United States)

    Verhaeghe, Thomas; Vlaemynck, Geertrui; De Block, Jan; Van Weyenberg, Stephanie; Hendrickx, Marc

    2016-04-15

    To optimize product quality of the cooked brown shrimp (Crangon crangon), quantitative data on the influence of all relevant process parameters (treatment time and temperature) on several quality attributes is required. Surprisingly, kinetic data and models on heat induced inactivation of important endogenous spoilage enzymes of the brown shrimp are not available today. In this study the thermal inactivation kinetics of the most important spoilage enzymes, proteases and polyphenoloxidase (PPO), were determined from isothermal heat treatments of enzyme extracts of the cephalothorax. For both enzymes, inactivation kinetics showed first order decay(s). Proteases showed two distinct stability fractions. A labile fraction, representing 42±2% of the total activity with kl,60°C=0.94±0.14 min(-1) and Ea,l=178±8.5 kJ/mol, and a stable fraction, representing 58±2%, with ks,60°C=0.020±0.002 min(-1) and Ea,s=155±7.0 kJ/mol. PPO showed a single fraction with k60°C=1.58±0.02 min(-1) and Ea=161±2.2 kJ/mol. Based on these results, the proteolytic activity, in particular the thermostable fraction, should be considered as a target in thermal processing of brown shrimp in relation to enzyme induced product quality changes during storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Reaction reversibility in α-pinene thermal isomerization: improving the kinetic model

    Science.gov (United States)

    Chibiryaev, A. M.; Ermakova, A.; Kozhevnikov, I. V.

    2011-08-01

    Revision of the experimental data on α-pinene thermal isomerization attained in supercritical ethanol allowed us to expand the reaction scheme, which includes now six main products and eleven reversible reactions. The equilibrium constants of every reaction ( K T, j and K Φ, j) were calculated to allow for reversibility of reactions. The thermochemical data of the pure compounds required to calculate constants K T, j and K Φ, j (standard enthalpy and entropy of formation Δf H° (298.15 K), Δf S° (298.15 K), heat capacity C p ( T), critical parameters T cr and p cr, boiling point T b, and the acentric factor ω) were preliminary estimated using the empirical Joback and Benson methods. A kinetic model based on the new expanded scheme of reversible reactions was successfully identified and its kinetic parameters k j (600 K) and E j were determined. Detailed examination of the new kinetic model allowed us to refine the generally accepted mechanism of α-pinene thermal isomerization and to distinguish additional features of the multistep process.

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

    Science.gov (United States)

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

    2018-01-01

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

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

    Science.gov (United States)

    2011-05-03

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

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

    DEFF Research Database (Denmark)

    Brandt, Peder; Henriksen, Ulrik Birk

    2000-01-01

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

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

    Science.gov (United States)

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

    1982-11-01

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

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

    Science.gov (United States)

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

    2017-06-01

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

  7. A Kinetics Investigation on the Nitro-Nitrite Rearrangement Mediated ...

    Indian Academy of Sciences (India)

    ... developed along with CL-20, TNAZ and ADN. DADNE is well-known for its insensitive nature and this has motivated the research in understanding the thermal and explosive decompositionbehaviour of DADNE. We have studied the thermal decomposition kinetics of DADNE employing two isoconversional methods viz., ...

  8. Evaluation of agricultural residues pyrolysis under non-isothermal conditions: Thermal behaviors, kinetics, and thermodynamics.

    Science.gov (United States)

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

    2017-10-01

    The thermal conversion characteristics, kinetics, and thermodynamics of agricultural residues, rape straw (RS) and wheat bran (WB), were investigated under non-isothermal conditions. TGA experiments showed that the pyrolysis characteristics of RS were quite different from those of WB. As reflected by the comprehensive devolatilization index, when the heating rate increased from 10 to 30Kmin-1, the pyrolysis performance of RS and WB were improved 5.27 and 5.96 times, respectively. The kinetic triplets of the main pyrolysis process of agricultural residues were calculated by the Starink method and the integral master-plots method. Kinetic analysis results indicated that the most potential kinetic models for the pyrolysis of RS and WB were D2 and F2.7, respectively. The thermodynamic parameters (ΔH, ΔG, and ΔS) were determined by the activated complex theory. The positive ΔH, positive ΔG, and negative ΔS at characteristic temperatures validated that the pyrolysis of agricultural residues was endothermic and non-spontaneous. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production.

    Science.gov (United States)

    Garcia-Soto, M J; Jimenez-Islas, H; Navarrete-Bolanos, J L; Rico-Martinez, R; Miranda-Lopez, R; Botello-Alvarez, J E

    2011-07-13

    The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.

  10. Effect of aggregation kinetics on the thermal conductivity of nanoscale colloidal solutions (nanofluid).

    Science.gov (United States)

    Prasher, Ravi; Phelan, Patrick E; Bhattacharya, Prajesh

    2006-07-01

    The thermal conductivity, k, of nanoscale colloidal suspensions (also known as nanofluid), consisting of nanoparticles suspended in a base liquid, is much higher than the thermal conductivity of the base liquid at very small volume fractions of the nanoparticles. However, experimental results from various groups all across the world have shown various anomalies such as a peak in the enhancement of k with respect to nanoparticle size, an increase as well as a decrease in the ratio of k of these colloidal solutions with the k of the base fluid with increasing temperature, and a dependence of k on pH and time. In this paper, the aggregation kinetics of nanoscale colloidal solutions are combined with the physics of thermal transport to capture the effects of aggregation on k. Results show that the observed anomalies reported in experimental work can be well described by taking aggregation kinetics into account. Finally, we show that colloidal chemistry plays a significant role in deciding the k of colloidal nanosuspensions.

  11. Thermal degradation kinetics and estimation of lifetime of radiation grafted polypropylene films

    Science.gov (United States)

    Mandal, Dev K.; Bhunia, Haripada; Bajpai, Pramod K.; Bhalla, Vinod Kumar

    2017-07-01

    In this research work, thermal stability and degradation behavior of acrylic acid grafted polypropylene (PP-g-PAAc) films were investigated by using thermogravimetric (TGA) analysis at four different heating rates 5, 10, 15 and 20 °C/min over a temperature range of 40-550 °C in nitrogen atmosphere. The kinetic parameters namely activation energy (Ea), reaction order (n) and frequency factor (Z) were calculated by three multiple heating rate methods. The thermal stability of PP-g-PAAc films is found to decrease with increase in degree of grafting. The TGA data and thermal kinetic parameters were also used to predict the lifetime of grafted PP films. The estimated lifetime of neat PP as well as grafted PP decreased with increase in temperature by all the three methods. Studies also indicated that Ea and lifetime of PP-g-PAAc films decreased with increase in degree of grafting, which may also be helpful in biodegradation of grafted PP films.

  12. Thermal behavior and pyrolytic degradation kinetics of polymeric mixtures from waste packaging plastics

    Directory of Open Access Journals (Sweden)

    R. Tuffi

    2018-01-01

    Full Text Available The thermal behavior and pyrolytic kinetic analysis of main waste polymers (polypropylene (PP, polyethylene film (PE, poly(ethylene terephthalate (PET, polystyrene (PS and three synthetic mixtures representing commingled postconsumer plastics wastes (CPCPWs output from material recovery facilities were studied. Thermogravimetry (TG pyrolysis experiments revealed that the thermal degradation of single polymers and the synthetic mixture enriched in PP occurred in one single step. The other two mixtures underwent a two-consecutive, partially overlapping degradation steps, whose peaks related to the first-order derivative of TG were deconvoluted into two distinct processes. Further TG experiments carried out on binary mixtures (PS/PP, PET/PP, PET/PEfilm and PP/PEfilm showed a thermal degradation reliance on composition, structure and temperatures of single polymer components. A kinetic analysis was made for each step using the Kissinger-Akahira-Sunose (KAS method, thus determining almost constant activation energy (Ea for pyrolysis of PS, PET, PP and PE film in the range 0.25<α<0.85, unlike for pyrolysis of CPCPWs, with particular reference to CPCPW1 and the second step of CPCPW2 and CPCPW3, both ascribable to degradation of PP and PE film. To account for the reliability of these values the integral isoconversional modified method developed by Vyazovkin was also applied.

  13. 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.

  14. Effect of various nanofillers on thermal stability and degradation kinetics of polymer nanocomposites.

    Science.gov (United States)

    Choudhury, Anusuya; Bhowmick, Anil K; Ong, Christopher; Soddemann, Matthias

    2010-08-01

    Structure of nanofillers and their subsequent interaction with a polymer is very important in determining thermal stability of polymer nanocomposite. In this paper, we tried to correlate structure of various 0, 1 and 2 dimensional nanofillers with the thermal stability of hydrogenated nitrile butadiene rubber (HNBR) nanocomposites. Organically modified and unmodified layered silicates such as montmorillonite (Cloisite Na+, Cloisite 30B and Cloisite 15A), rod-like fibrous filler (sepiolite) and spherical nanoparticles (nanosilica) were chosen for this purpose. A significant improvement in thermal stability (obtained by thermogravimeric analysis and differential scanning calorimetry) was observed for silica-filled nanocomposites. However, the activation energy of the nanocomposites calculated by different kinetic methods (both non-isothermal and isothermal methods) was found to be significantly high for sepiolite, 30B and silica-filled nanocomposites. The results were explained with the help of structure of the nanofillers, their interaction with the elastomer and the subsequent dispersion, as measured by X-ray diffraction, transmission electron microscopy and atomic force microscopy. From these analyses it was concluded that organically modified montmorillonite, sepiolite and nanosilica increase the thermal stability of the nanocomposite to a great extent due to the interaction of the reactive groups on the surface of these fillers with the polymer and high thermal stability of these inorganic fillers. Finally, degradation mechanism of HNBR in presence of the nanofillers at severe operating temperatures was investigated with the help of FTIR spectroscopy.

  15. From kinetic to collective behavior in thermal transport on semiconductors and semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tomas, C. de; Lopeandia, A. F.; Alvarez, F. X., E-mail: xavier.alvarez@uab.cat [Department of Physics, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Cantarero, A. [Materials Science Institute, University of Valencia, P. O. Box 22085, 46071 Valencia (Spain)

    2014-04-28

    We present a model which deepens into the role that normal scattering has on the thermal conductivity in semiconductor bulk, micro, and nanoscale samples. Thermal conductivity as a function of the temperature undergoes a smooth transition from a kinetic to a collective regime that depends on the importance of normal scattering events. We demonstrate that in this transition, the key point to fit experimental data is changing the way to perform the average on the scattering rates. We apply the model to bulk Si with different isotopic compositions obtaining an accurate fit. Then we calculate the thermal conductivity of Si thin films and nanowires by only introducing the effective size as additional parameter. The model provides a better prediction of the thermal conductivity behavior valid for all temperatures and sizes above 30 nm with a single expression. Avoiding the introduction of confinement or quantum effects, the model permits to establish the limit of classical theories in the study of the thermal conductivity in nanoscopic systems.

  16. Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado Kinetic study of the catalyzed decomposition of hydrogen peroxide on activated carbon

    Directory of Open Access Journals (Sweden)

    Elihu Paternina

    2009-01-01

    Full Text Available The kinetic study of decomposition of hydrogen peroxide catalyzed by activated carbon was carried out. The effect of concentrations of reactants and temperature were experimentally studied. Kinetic data were evaluated using differential method of initial rates of reaction. When a typical kinetic law for reactions in homogeneous phase is used, first order of reaction is obtained for hydrogen peroxide and activated carbon, and activation energy of 27 kJ mol-1 for the reaction was estimated. Experimentally was observed that surface of activated carbon is chemically modified during decomposition of hydrogen peroxide, based on this result a scheme of reaction was proposed and evaluated. Experimental data fits very well to a Langmuir- Hinshelwood kinetic model and activation energy of 40 kJ mol-1 was estimated for reaction in heterogeneous phase.

  17. 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.

  18. 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.

  19. Thermal behavior and transformation kinetics of titanium dioxide nanocrystallites prepared by coupling agents

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.C. [School of Dentistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Wang, Y.T. [Department of Medical Research and Education, Chen Hsin General Hospital, 45 Cheng-Hsin Street, Pai-Tou, Taipei 11220, Taiwan (China); Shih, C.J., E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

    2010-02-04

    Coupling agents have been widely used to retard the sintering of silver paste and minimize co-firing defects due to densification mismatch between silver and dielectrics. The thermal-decomposition and crystallization behavior of the coupling agent is a subject of great concern. To elucidate what is responsible for the oxidation, Ti organometallic compounds were calcined at different temperatures (350, 400, 500, 600 {sup o}C) for 2 h and the crystallization behavior was determined by X-ray diffraction (XRD). The activation energy for crystallization of coupling agents was studied by using isothermal methods. According to the quantitative XRD method, the values calculated by the Johnson-Mehi-Avrami equation are 134.9 kJ mol{sup -1}. The growth morphology parameters are 1.061, 0.915, 1.016 respectively. Combining the results of DTA, XRD and TEM, it is found that formation of nanocrystallized titania accompanies the combustion of organometallic compounds.

  20. Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

    Science.gov (United States)

    DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

    2008-02-01

    Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.

  1. 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

  2. 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

  3. Kinetics and mechanism of free-surface decomposition of Group IIA and IIB hydroxides analyzed thermogravimetrically by the third-law method

    Energy Technology Data Exchange (ETDEWEB)

    L' vov, Boris V.; Ugolkov, Valery L

    2004-04-08

    The third-law method was applied to systematic investigation of free-surface decomposition kinetics of Group IIA and IIB hydroxides. The E parameters of the Arrhenius equation (in kJ mol{sup -1}) are as follows: 124.8 (Be), 166.4 (Mg), 172.9 (Canada), 181.7 (Sr), 173.4 (Ba), 122.0 (Zn) and 124.7 (Cd). In accord with the physical approach, the obtained values of the E parameter are interpreted as the specific enthalpies of primary gasification reaction with consideration for the partial transfer of condensation energy of low-volatility oxide to the reactant. The {tau} parameters responsible for consumption of condensation energy by the reactants for all hydroxides except of Ba(OH){sub 2} and Cd(OH){sub 2} are higher than 0.50. The maximum value (0.74) was found for Be(OH){sub 2}. Together with the available values of {tau} parameter for eight other reactants, they are in good correlation with the supersaturating degrees and/or condensation energies of the low-volatile products at the decomposition temperatures. This makes it possible a priori evaluation of the {tau} parameter on the basis of the thermodynamic characteristics of the low-volatile product.

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

    Science.gov (United States)

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

    2014-11-01

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

  5. Non-isothermal kinetic analysis of processes occurring during thermal treatment of kaolinite

    Science.gov (United States)

    Ondro, Tomáš; Trník, Anton

    2017-07-01

    A non-isothermal kinetic analysis of processes occurring during thermal treatment of kaolinite is carried out using differential thermal analysis on powder samples with heating rates from 1 to 10 °C min-1 in static air atmosphere. For the parameterization of dehydroxylation process and crystallization of Al-Si spinel phase from metakaolinite the Kissinger method is used. The determined values of apparent activation energy for the dehydroxylation of kaolinite and formation of Al-Si spinel phase are (163 ± 11) kJ mol-1 and (826 ± 16) kJ mol-1, respectively. For the dehydroxylation of kaolinite the diffusion controlled growth of a new phase with a decreasing nucleation rate is determined as a mechanism of the process. The results also show that the formation of Al-Si spinel phase from metakaolinite is controlled by grain edge nucleation after saturation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-05

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

  7. 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.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cui, BZ; Marinescu, M; Liu, JF

    2013-12-14

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

  10. 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.

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

    Science.gov (United States)

    Haydary, J; Susa, D; Dudáš, J

    2013-05-01

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

  12. 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.

  13. Efficient, high rep rate, large-bore kinetically enhanced copper vapor laser with low (thermal assembly.

    Science.gov (United States)

    Singh, Bijendra; Subramaniam, V V; Daultabad, S R; Chakraborty, Ashim

    2009-10-01

    Large-bore kinetically enhanced copper vapor laser (CVL) based on new thermal assembly consisting of different density zones of insulation material (alumina fiber) around the discharge tube is demonstrated for the first time with efficiency eta > or = 1% at extremely low specific input power (SIP) of insulation material, efficiency of approximately 1.2% was achieved at lowest SIP of approximately 0.75 kW/l. Net reduction in the input power of approximately 1 kW was observed on using this thermal assembly as compared to nonprofiled thermal assembly. These results show significant improvement (25%-30%) at low input requirements of the laser on using new thermal assembly around the discharge tube with overall electro-optical efficiency eta > or = 1%. Maximum laser power achieved from the laser was approximately 78 W at approximately 9.8 kHz rep rate with efficiency of approximately 1.4%. This large-bore CVL is also capable of operating efficiently (eta approximately 1%) at high rep rate of -17 kHz with maximum laser power of approximately 50 W. Performance of the laser under various operating conditions is also presented in this short paper.

  14. Kinetics and thermodynamics of the thermal inactivation and chaperone assisted folding of zebrafish dihydrofolate reductase.

    Science.gov (United States)

    Thapliyal, Charu; Jain, Neha; Rashid, Naira; Chaudhuri Chattopadhyay, Pratima

    2017-11-11

    The maintenance of thermal stability is a major issue in protein engineering as many proteins tend to form inactive aggregates at higher temperatures. Zebrafish DHFR, an essential protein for the survival of cells, shows irreversible thermal unfolding transition. The protein exhibits complete unfolding and loss of activity at 50 °C as monitored by UV-Visible, fluorescence and far UV-CD spectroscopy. The heat induced inactivation of zDHFR follows first-order kinetics and Arrhenius law. The variation in the value of inactivation rate constant, k with increasing temperatures depicts faster inactivation at elevated temperatures. We have attempted to study the chaperoning ability of a shorter variant of GroEL (minichaperone) and compared it with that of conventional GroEL-GroES chaperone system. Both the chaperone system prevented the aggregation and assisted in refolding of zDHFR. The rate of thermal inactivation was significantly retarded in the presence of chaperones which indicate that it enhances the thermal stability of the enzyme. As minichaperone is less complex, and does not require high energy co-factors like ATP, for its function as compared to conventional GroEL-GroES system, it can act as a very good in vitro as well as in vivo chaperone model for monitoring assisted protein folding phenomenon. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

  16. 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.

  17. 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.

  18. Kinetic and thermodynamic investigation of mancozeb degradation in tomato homogenate during thermal processing.

    Science.gov (United States)

    Certel, Muharrem; Cengiz, Mehmet F; Akçay, Mehmet

    2012-02-01

    The kinetic and thermodynamic parameters of mancozeb degradation in tomato homogenates under the conditions prevailing in the manufacture of tomato products (at 60-100 °C for 0-60 min) were investigated. A gas chromatography-mass spectrometry method was used to analyse residual mancozeb in tomato homogenate. Ethylenethiourea (ETU), the main toxic degradation product of mancozeb, was measured by high-performance liquid chromatography (HPLC)-with photodiode array detector (PDA). The degradation of mancozeb and the formation of ETU in tomato homogenates were adequately described as first-order kinetics. Dependence of the rate constant followed the Arrhenius relationship. Apparent activation energies, temperature coefficients, half time and time to reduce to 90% of the initial value of mancozeb were calculated as kinetic parameters. The thermodynamic parameters of mancozeb were also described as Δg(d) = - 2.440 and 7.074 kJ mol⁻¹; Δh(d) = - 32.555 and - 42.767 kJ mol⁻¹; Δs(d) = - 0.090 and - 0.150 kJ mol⁻¹ K⁻¹; K(e) = 0.414 and 9.797 L g⁻¹ for 333 and 373 K respectively. Current findings may shed light on the reduction of mancozeb residue and its toxic degradation product during thermal processing of tomatoes and may also be valuable in awareness and prevention of potential risks from dietary exposure. Copyright © 2011 Society of Chemical Industry.

  19. Kinetic study on thermal denaturation of hen egg-white lysozyme involving precipitation.

    Science.gov (United States)

    Nohara, D; Mizutani, A; Sakai, T

    1999-01-01

    A kinetic study on the thermal denaturation accompanying precipitation of hen egg-white lysozyme was performed at temperatures between 50 and 90 degrees C. Visible precipitation occurred at lysozyme concentrations higher than 10(-5)M. Even at the concentration of 10(-6)M where no visible precipitation was observed, irreversible and reversible denaturation could be clearly discriminated. The former involves two different reactions with activation energies of approximately 93 and 50 kJ x mol(-1). On the other hand, enthalpy and entropy changes in the latter are 443 kJ x mol(-1) and 1280 J x K(-1) x mol(-1), respectively, indicating a large conformational change. The contradiction that the denaturation or deactivation reaction fitted first-order reaction kinetics while its rate constant depended on the protein concentration, was resolved by newly proposed schemes. The apparent first-order rate constant obtained experimentally depended on the initial protein concentration being on the order of almost unity. Moreover, it was revealed that the apparent first-order reaction involved a second-order reaction that characterized the aggregation of denatured protein molecules. The theory developed here explained reasonably the thermal denaturation accompanying precipitation that occurs at high protein concentration and at high temperature, and was also successfully applied to the lower concentration range with no accompanying precipitation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

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

    Science.gov (United States)

    Gaur, Rama; Jeevanandam, P.

    2015-03-01

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

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

    Science.gov (United States)

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

    2012-01-25

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

  3. 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

  4. Kinetic model of the thermal pyrolysis of chrome tanned leather treated with NaOH under different conditions using thermogravimetric analysis.

    Science.gov (United States)

    Bañón, E; Marcilla, A; García, A N; Martínez, P; León, M

    2016-02-01

    The thermal decomposition of chrome tanned leather before and after a soaking treatment with NaOH was studied using thermogravimetric analysis (TGA). The effect of the solution concentration (0.2M and 0.5M) and the soaking time (5min and 15min) was evaluated. TGA experiments at four heating rates (5, 10, 15 and 20°Cmin(-1)) were run in a nitrogen atmosphere for every treatment condition. A kinetic model was developed considering the effect of the three variables studied, i.e.: the NaOH solution concentration, the soaking time and the heating rate. The proposed model for chrome tanned leather pyrolysis involves a set of four reactions, i.e.: three independent nth order reactions, yielding the corresponding products and one of them undergoing a successive cero order reaction. The model was successfully applied simultaneously to all the experimental data obtained. The evaluation of the kinetic parameters obtained (activation energy, pre-exponential factor and reaction order) allowed a better understanding of the effect of the alkali treatment on these wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. 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.

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

    Science.gov (United States)

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

    2013-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-01

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

  8. Raman study of the photopolymer formation in the {Pt(dbdtc)2}·C60 fullerene complex and the decomposition kinetics of the photo-oligomers

    Science.gov (United States)

    Meletov, K. P.; Velkos, G.; Arvanitidis, J.; Christofilos, D.; Kourouklis, G. A.

    2017-08-01

    The photopolymer formation in the fullerene layers of the C60 complex with platinum dibenzyldithiocarbamate is reported for the first time. The photo-oligomer peaks appear in the Raman spectra near the Ag(2) mode of the C60 molecule upon sample illumination with various laser wavelengths. The photo-oligomers are unstable upon heating and revert back to the C60 monomeric state. The activation energy of the thermal decomposition, obtained from the Arrhenius dependence of the decay time constant on temperature, is (1.12 ± 0.11) eV and the photo-oligomers decompose at ∼130 °C, being more fragile than the crystalline polymers of C60.

  9. 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.

  10. Kinetics of free-surface decomposition of magnesium, strontium and barium carbonates analyzed thermogravimetrically by the third-law method

    Energy Technology Data Exchange (ETDEWEB)

    L' vov, Boris V.; Ugolkov, Valery L

    2004-01-09

    The results of our thermogravimetric experiments on the decompositions of MgCO{sub 3}, SrCO{sub 3} and BaCO{sub 3} powders and some data reported in the literature were used for the determination of the E parameter of the Arrhenius equation by the third-law method and estimation of the self-cooling effect on the results of these determinations. The experimental values of the E parameters for these carbonates (218, 286 and 302 kJ mol{sup -1}) are much higher than the enthalpies of equilibrium reactions (up to solid oxide and CO{sub 2}) and the values accepted by TA community as the reference data. At the same time, these data are in a good agreement with the mechanism of congruent dissociative evaporation of carbonates with the simultaneous condensation of low-volatility oxides. Differences in the magnitudes of the {tau} parameter responsible for the consumption of condensation energy by the reactant are revealed. Instead of expected 0.50, the magnitudes of the {tau} parameter for Mg, Sr and Ba carbonates are as follows: 0.47, 0.42 and 0.10.

  11. Thermal stability and degradation kinetics of polyphenols and polyphenylenediamines enzymatically synthesized by horseradish peroxidase

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hansol; Ryu, Keungarp [University of Ulsan, Ulsan (Korea, Republic of); Kwon, Oyul [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2015-09-15

    Various substituted phenols and phenylenediamines were enzymatically polymerized by horseradish peroxidase in 80% (v/v) organic solvents-aqueous buffer (100 mM sodium acetate, pH 5) mixtures with H{sub 2}O{sub 2} as the oxidant. The thermal stability of the polymers was investigated by thermogravimetric analysis (TGA) and represented by the char yield (wt% of the initial polymer mass) after being heated at 800 .deg. C. Poly(p-phenylphenol) had the highest thermal stability among the synthesized polymers with a char yield of 47 wt%. The polymers containing amino groups such as poly(p-aminophenol) and polyphenylenediamines were also shown to possess high thermal stabilities. The activation energies for the thermal degradation of the polymers determined by derivative thermogravimetric analysis (DTG) using Horowitz-Metzger's pseudo-first-order kinetics were in the range between 23-65 kJ/mol and comparable to those of the chemically synthesized polymers. Dynamic structural changes of the enzymatically synthesized polymers upon heating were studied by differential scanning calorimetry (DSC). The DSC curves of poly(p-phenylphenol) showed a broad exothermic peaks between 150-250 .deg. C, indicating that the polymer undergoes complex structural transitions in the temperature range. On the other hand, the DSC curves of the poly(p-aminophenol) and the poly(p-phenylenediamine) which contain amino groups showed strong sharp endothermic peaks near 150 .deg. C, implying that these polymers possess homogeneous oriented structures which undergo a concerted structural disintegration upon heating.

  12. Ozone Decomposition on the Surface of Metal Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Batakliev Todor Todorov

    2014-12-01

    Full Text Available The catalytic decomposition of ozone to molecular oxygen over catalytic mixture containing manganese, copper and nickel oxides was investigated in the present work. The catalytic activity was evaluated on the basis of the decomposition coefficient which is proportional to ozone decomposition rate, and it has been already used in other studies for catalytic activity estimation. The reaction was studied in the presence of thermally modified catalytic samples operating at different temperatures and ozone flow rates. The catalyst changes were followed by kinetic methods, surface measurements, temperature programmed reduction and IR-spectroscopy. The phase composition of the metal oxide catalyst was determined by X-ray diffraction. The catalyst mixture has shown high activity in ozone decomposition at wet and dry O3/O2 gas mixtures. The mechanism of catalytic ozone degradation was suggested.

  13. Descomposicion termica del diperoxido de pinacolona (3,6-diterbutil-3,6-dimetil-1,2,4,5-tetraoxaciclohexano en solución de 2-metoxietanol Thermal decomposition of pinacolone diperoxide (3,6-ditertbutyl-3,6-dimethyl-1,2,4,5-tetraoxacyclohexane in 2-methoxyethanol solution

    Directory of Open Access Journals (Sweden)

    Gladys N. Eyler

    2002-05-01

    Full Text Available The thermal decomposition reaction of pinacolone diperoxide (DPP; 0.02 mol kg-1 in 2-methoxyethanol solution studied in the temperature range of 110.0-150.0 °C, follows a first-order kinetic law up to at least 50% DPP conversion. The organic products observed were pinacolone, methane and tert-butane. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DPP in 2-methoxyethanol were calculated (deltaH# = 43.8 ± 1.0 kcal mol-1 and deltaS# = 31.9 ± 2.6 cal mol-1K-1 and compared with those obtained in other solvents to evaluate the solvent effect.

  14. Kinetic vaporization of heavy metals during fluidized bed thermal treatment of municipal solid waste.

    Science.gov (United States)

    Yu, Jie; Sun, Lushi; Xiang, Jun; Hu, Song; Su, Sheng

    2013-02-01

    Heavy metals volatilization during thermal treatment of model solid waste was theoretically and experimentally investigated in a fluidized bed reactor. Lead, cadmium, zinc and copper, the most four conventional heavy metals were investigated. Particle temperature model and metal diffusion model were established to simulate the volatilization of CdCl(2) evaporation and investigate the possible influencing factors. The diffusion coefficient, porosity and particle size had significant effects on metal volatilization. The higher diffusion coefficient and porosity resulted in the higher metal evaporation. The influence of redox conditions, HCl, water and mineral matrice were also investigated experimentally. The metal volatilization can be promoted by the injection of HCl, while oxygen played a negative role. The diffusion process of heavy metals within particles also had a significant influence on kinetics of their vaporization. The interaction between heavy metals and mineral matter can decrease metal evaporation amount by forming stable metallic species. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Growth of Ni2Si by rapid thermal annealing: Kinetics and moving species

    Science.gov (United States)

    Ma, E.; Lim, B. S.; Nicolet, M.-A.; Natan, M.

    1987-10-01

    The growth kinetics is characterized and the moving species is identified for the formation of Ni2Si by Rapid Thermal Annealing (RTA) of sequentially deposited Si and Ni films on a Si substrate. The interfacial Ni2Si layer grows as the square root of time, indicating that the suicide growth process is diffusion-limited. The activation energy is 1.25±0.2 eV in the RTA temperature range of 350 450° C. The results extend those of conventional steady-state furnace annealing quite fittingly, and a common activation energy of 1.3±0.2 eV is deduced from 225° to 450° C. The marker experiment shows that Ni is the dominant moving species during Ni2Si formation by RTA, as is the case for furnace annealing. It is concluded that the two annealing techniques induce the same growth mechanisms in Ni2Si formation.

  16. The influence of carbon black on curing kinetics and thermal aging of acrylonitrile–butadiene rubber

    Directory of Open Access Journals (Sweden)

    Jaroslava Budinski-Simendić

    2009-10-01

    Full Text Available Elastomers based on a copolymer of butadiene and acrylonitrile (NBR have excellent oil resistance but are very sensitive for degradation at very high temperatures. The aim of this applicative contribution was to determine the effect of high abrasion furnace carbon black with primary particle size 46 nm on aging properties of elastomeric materials based on NBR as network precursor. The curing kinetics was determined using the rheometer with an oscillating disk, in which the network formation process is registered by the torque variation during time. The vulcanizates were obtained in a hydraulic press at 150 °C. The mechanical properties of elastomeric composites were determined before and after thermal aging in an air circulating oven. The reinforcing effect of the filler particles was assessed according to mechanical properties before and after aging.

  17. High pressure thermal inactivation of Clostridium botulinum type E endospores - kinetic modeling and mechanistic insights.

    Science.gov (United States)

    Lenz, Christian A; Reineke, Kai; Knorr, Dietrich; Vogel, Rudi F

    2015-01-01

    Cold-tolerant, neurotoxigenic, endospore forming Clostridium (C.) botulinum type E belongs to the non-proteolytic physiological C. botulinum group II, is primarily associated with aquatic environments, and presents a safety risk for seafood. High pressure thermal (HPT) processing exploiting the synergistic effect of pressure and temperature can be used to inactivate bacterial endospores. We investigated the inactivation of C. botulinum type E spores by (near) isothermal HPT treatments at 300-1200 MPa at 30-75°C for 1 s to 10 min. The occurrence of heat and lysozyme susceptible spore fractions after such treatments was determined. The experimental data were modeled to obtain kinetic parameters and represented graphically by isoeffect lines. In contrast to findings for spores of other species and within the range of treatment parameters applied, zones of spore stabilization (lower inactivation than heat treatments alone), large heat susceptible (HPT-induced germinated) or lysozyme-dependently germinable (damaged coat layer) spore fractions were not detected. Inactivation followed first order kinetics. Dipicolinic acid release kinetics allowed for insights into possible inactivation mechanisms suggesting a (poorly effective) physiologic-like (similar to nutrient-induced) germination at ≤450 MPa/≤45°C and non-physiological germination at >500 MPa/>60-70°C. Results of this study support the existence of some commonalities in the HPT inactivation mechanism of C. botulinum type E spores and Bacillus spores although both organisms have significantly different HPT resistance properties. The information presented here contributes to closing the gap in knowledge regarding the HPT inactivation of spore formers relevant to food safety and may help industrial implementation of HPT processing. The markedly lower HPT resistance of C. botulinum type E spores compared with the resistance of spores from other C. botulinum types could allow for the implementation of milder

  18. High pressure thermal inactivation of Clostridium botulinum type E endospores – kinetic modeling and mechanistic insights

    Science.gov (United States)

    Lenz, Christian A.; Reineke, Kai; Knorr, Dietrich; Vogel, Rudi F.

    2015-01-01

    Cold-tolerant, neurotoxigenic, endospore forming Clostridium (C.) botulinum type E belongs to the non-proteolytic physiological C. botulinum group II, is primarily associated with aquatic environments, and presents a safety risk for seafood. High pressure thermal (HPT) processing exploiting the synergistic effect of pressure and temperature can be used to inactivate bacterial endospores. We investigated the inactivation of C. botulinum type E spores by (near) isothermal HPT treatments at 300–1200 MPa at 30–75°C for 1 s to 10 min. The occurrence of heat and lysozyme susceptible spore fractions after such treatments was determined. The experimental data were modeled to obtain kinetic parameters and represented graphically by isoeffect lines. In contrast to findings for spores of other species and within the range of treatment parameters applied, zones of spore stabilization (lower inactivation than heat treatments alone), large heat susceptible (HPT-induced germinated) or lysozyme-dependently germinable (damaged coat layer) spore fractions were not detected. Inactivation followed first order kinetics. Dipicolinic acid release kinetics allowed for insights into possible inactivation mechanisms suggesting a (poorly effective) physiologic-like (similar to nutrient-induced) germination at ≤450 MPa/≤45°C and non-physiological germination at >500 MPa/>60–70°C. Results of this study support the existence of some commonalities in the HPT inactivation mechanism of C. botulinum type E spores and Bacillus spores although both organisms have significantly different HPT resistance properties. The information presented here contributes to closing the gap in knowledge regarding the HPT inactivation of spore formers relevant to food safety and may help industrial implementation of HPT processing. The markedly lower HPT resistance of C. botulinum type E spores compared with the resistance of spores from other C. botulinum types could allow for the implementation of

  19. High pressure thermal inactivation of Clostridium botulinum type E endospores – kinetic modeling and mechanistic insights

    Directory of Open Access Journals (Sweden)

    Christian Andreas Lenz

    2015-07-01

    Full Text Available Cold-tolerant, neurotoxigenic, endospore forming Clostridium (C. botulinum type E belongs to the non-proteolytic physiological C. botulinum group II, is primarily associated with aquatic environments, and presents a safety risk for seafood. High pressure thermal (HPT processing exploiting the synergistic effect of pressure and temperature can be used to inactivate bacterial endospores.We investigated the inactivation of C. botulinum type E spores by (near isothermal HPT treatments at 300 – 1200 MPa at 30 – 75 °C for 1 s – 10 min. The occurrence of heat and lysozyme susceptible spore fractions after such treatments was determined. The experimental data were modeled to obtain kinetic parameters and represented graphically by isoeffect lines. In contrast to findings for spores of other species and within the range of treatment parameters applied, zones of spore stabilization (lower inactivation than heat treatments alone, large heat susceptible (HPT-induced germinated or lysozyme-dependently germinable (damaged coat layer spore fractions were not detected. Inactivation followed 1st order kinetics. DPA release kinetics allowed for insights into possible inactivation mechanisms suggesting a (poorly effective physiologic-like (similar to nutrient-induced germination at ≤ 450 MPa/≤ 45 °C and non-physiological germination at >500 MPa/>60 – 70 °C.Results of this study support the existence of some commonalities in the HPT inactivation mechanism of C. botulinum type E spores and Bacillus spores although both organisms have significantly different HPT resistance properties. The information presented here contributes to closing the gap in knowledge regarding the HPT inactivation of spore formers relevant to food safety and may help industrial implementation of HPT processing. The markedly lower HPT resistance of C. botulinum type E spores than spores from other C. botulinum types, could allow for the implementation of milder processes without

  20. Characterization and thermal inactivation kinetics of highly thermostable ramie leaf β-amylase.

    Science.gov (United States)

    He, Liqin; Park, Sung-Hoon; Hai Dang, Nguyen Dang; Duong, Hoa Xo; Duong, Thi Phung Cac; Tran, Phuong Lan; Park, Jong-Tae; Ni, Li; Park, Kwan-Hwa

    2017-06-01

    We characterized ramie leaf β-amylase, and determined its thermostability and kinetic parameters. The enzyme was purified 53-fold using ammonium sulfate fractionation (40-60% saturation), anion exchange chromatography on DEAE-cellulose and gel permeation chromatography on Superdex-200. The purified enzyme was identified as β-amylase with molecular mass of 42kD. The enzyme displayed Km and kcat values for soluble potato starch of 1.1mg/mL and 7.8s-1, respectively. The enzyme had a temperature optimum of 65°C, and its activity at 70°C was 92% of that at the optimal temperature after a 15-min incubation. Furthermore, enzyme activity was stable during treatment at 55°C for 60min but was inactivated rapidly at >75°C. This thermal behavior indicates that ramie leaf β-amylase has excellent intermediate temperature-stable enzyme properties for the baking and bio-industries. Inactivation of the enzyme followed first-order kinetics in the range of 55-80°C. The enthalpy change of thermal inactivation (ΔH‡), ΔG‡, and ΔS‡ were 237.2kJ/mol, 107.7kJ/mol, and 0.39kJ/molK at 333K, respectively. The D-value at 65°C (=110min) and the z-value (=9.4°C) are given for food processing. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Picrocrocin kinetics in aqueous saffron spice extracts (Crocus sativus L.) upon thermal treatment.

    Science.gov (United States)

    Sánchez, Ana M; Carmona, Manuel; Jarén-Galán, Manuel; Mosquera, M Isabel Mínguez; Alonso, Gonzalo L

    2011-01-12

    The kinetics of picrocrocin degradation in aqueous extracts of saffron upon thermal treatment from 5 to 70 °C have been studied, together with the degradation of purified picrocrocin in water at 100 °C. The best fits to experimental data were found for a second-order kinetics model. Picrocrocin showed high stability with half-life periods (t(1/2)) ranging from >3400 h at 5 °C in saffron extracts to 9 h in the experiments with purified picrocrocin at 100 °C. In saffron extracts, the evolution of the rate constant (k) with temperature showed maximum values at 35 °C, and filtration of the extracts contributed to picrocrocin stability. In the case of purified picrocrocin, the generation of safranal in the first 5 h (yield up to 7.4%) was confirmed. Spectrometric parameters used in saffron quality control (E(1cm)(1%) 257 nm and ΔΕ(pic)) were not appropriate for documenting the evolution of picrocrocin.

  2. Kinetic modeling of the thermal evolution of crude oils in sedimentary basins; Modelisation cinetique de l'evolution thermique des petroles dans les gisements

    Energy Technology Data Exchange (ETDEWEB)

    Bounaceur, R.

    2001-01-15

    The aim of this work is to obtain a better understanding of the reactions involved in the thermal cracking of crude oil in sedimentary basins, and to study its kinetics as a function of temperature and pressure. We study the kinetics of pyrolysis of alkanes at low temperature, high pressure and high conversion and we propose three methods of reduction of the corresponding mechanisms. Several compounds having an inhibiting or accelerating effect on the rate of decomposition of alkanes were also studied. This research led to the construction of a general kinetic model of 5200 elementary steps representing the pyrolysis of a complex mixture of 52 molecules belonging to various chemical families: 30 linear alkanes (from CH{sub 4} to C{sub 30}H{sub 62}), 10 branched-chain alkanes (including pristane and phytane), 2 naphthenes (propyl-cyclo-pentane and propyl-cyclohexane), tetralin, 1-methyl-indan, 4 aromatics (benzene, toluene, butyl-benzene and decyl-benzene), 3 hetero-atomic compounds (a disulfide, a mercaptan and H{sub 2}S). This model is compared to experimental data coming from the pyrolysis of two oils: one from the North Sea and the other from Pematang. The results obtained show a good agreement between the experimental and simulated values. Then, we simulated the cracking of these two oils by using the following burial scenario: initial temperature of 160 degrees, 50 m per million years (ma) in a constant geothermal gradient of 30 degrees C/km, implying a heating rate of 1.5 degrees C/ma. Under these conditions, our model shows that these two oils start to crack only towards 210-220 degrees C and that their time of half-life corresponds to a temperature around 230-240 degrees C. The model also makes it possible to simulate the evolution of geochemical parameters such as the GOR, the API degree... (author)

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

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2012-01-01

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

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

    Science.gov (United States)

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

    1995-05-01

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  6. Thermal degradation kinetics of nylon6/GF/crysnano nanoclay nanocomposites by TGA

    Directory of Open Access Journals (Sweden)

    SHAHRYAR PASHAEI

    2011-06-01

    Full Text Available Nylon 6 is extensively used in engineering applications because of its unique characteristics such as low price, low viscosity, high toughness, shelf lubricating behaviour and high chemical resistance. Nanocomposites based on PA-6 were prepared by melt extrusion and an adjacent injection moulding process. Mechanical and thermomechanical properties have been investigated by tensile testing and dynamic mechanical analysis. To evaluate the potential of crysnano nanoclays as a new candidate in the class of nanofillers, the properties of the crysnano nanoclays nanocomposites has been compared to those of glass fiber. Thermal characteristics were performed using thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and dynamic mechanical analysis (DMA. With increase in filler loading, the enthalpy of melting (Hm obtained from DSC curves was reduced as compared to pristine nylon 6. All the nanocompsoites were stable upto 205 °C. Degradation kinetic parameters have been calculated for thermal degradation processes using the composites using three mathematical models, namely Horowitz–Metzger, Coats–Redfern and Broido’s methods.

  7. Kinetic study of the thermal denaturation of a hyperthermostable extracellular α-amylase from Pyrococcus furiosus.

    Science.gov (United States)

    Brown, I; Dafforn, T R; Fryer, P J; Cox, P W

    2013-12-01

    Hyperthermophilic enzymes are of industrial importance and interest, especially due to their denaturation kinetics at commercial sterilisation temperatures inside safety indicating time-temperature integrators (TTIs). The thermal stability and irreversible thermal inactivation of native extracellular Pyrococcus furiosus α-amylase were investigated using differential scanning calorimetry, circular dichroism and Fourier transform infrared spectroscopy. Denaturation of the amylase was irreversible above a Tm of approximately 106°C and could be described by a one-step irreversible model. The activation energy at 121°C was found to be 316kJ/mol. Using CD and FT-IR spectroscopy it was shown that folding and stability greatly increase with temperature. Under an isothermal holding temperature of 121°C, the structure of the PFA changes during denaturation from an α-helical structure, through a β-sheet structure to an aggregated protein. Such data reinforces the use of P. furiosus α-amylase as a labile species in TTIs. © 2013.

  8. Thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon

    Science.gov (United States)

    Wang, Xutong; Zeng, Mo; Nollmann, Niklas; Wilde, Gerhard; Wang, Jiang; Tang, Chengying

    2017-06-01

    Rapidly quenched Pd82Si18 ribbon was prepared by melt spinning. The thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon were investigated by differential scanning calorimeter measurements. Its structure was investigated by X-ray diffraction and transmission electronic microscopy. The activation energy was calculated by the Kissinger method, and the nucleation and growth during non-isothermal crystallization were investigated by the local activation energy and local Avrami exponent. The average activation energy for Pd82Si18 amorphous ribbon based on the Kissinger method is 330.672 kJ/mol, indicating that it has high thermal stability. The local activation energy of the glass ribbon was determined by the Kissinger-Akahira-Sunose method, and the local Avrami exponent was obtained based on the Johnson-Mehl-Avrami model. The calculated local activation energy increases to a maximum when the crystallization column fraction reaches 0.3, and it then decreases, which shows that crystallization is a multistep process. The local Avrami exponent indicates that the crystallization process of Pd82Si18 amorphous ribbon is controlled by volume nucleation with three-dimensional growth at various nucleation rates.

  9. Thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon

    Directory of Open Access Journals (Sweden)

    Xutong Wang

    2017-06-01

    Full Text Available Rapidly quenched Pd82Si18 ribbon was prepared by melt spinning. The thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon were investigated by differential scanning calorimeter measurements. Its structure was investigated by X-ray diffraction and transmission electronic microscopy. The activation energy was calculated by the Kissinger method, and the nucleation and growth during non-isothermal crystallization were investigated by the local activation energy and local Avrami exponent. The average activation energy for Pd82Si18 amorphous ribbon based on the Kissinger method is 330.672 kJ/mol, indicating that it has high thermal stability. The local activation energy of the glass ribbon was determined by the Kissinger–Akahira–Sunose method, and the local Avrami exponent was obtained based on the Johnson–Mehl–Avrami model. The calculated local activation energy increases to a maximum when the crystallization column fraction reaches 0.3, and it then decreases, which shows that crystallization is a multistep process. The local Avrami exponent indicates that the crystallization process of Pd82Si18 amorphous ribbon is controlled by volume nucleation with three-dimensional growth at various nucleation rates.

  10. Kinetic properties and thermal stabilities of mutant forms of mitochondrial aspartate aminotransferase.

    Science.gov (United States)

    Azzariti, A; Vacca, R A; Giannattasio, S; Merafina, R S; Marra, E; Doonan, S

    1998-07-28

    Kinetic properties and thermal stabilities of the precursor form of mitochondrial aspartate aminotransferase, the mature form lacking 9 amino acids from the N-terminus, and forms of the mature protein in which cysteine-166 had been mutated to serine or alanine were compared with those of the mature enzyme. The precursor and the cysteine mutants showed moderately impaired catalytic properties consistent with decreased ability to undergo transition from the open to the closed conformation which is an integral part of the mechanism of action of the enzyme. The deletion mutant had a kcat only 2% of that of the mature enzyme but also much reduced Km values for both substrates. In addition it showed enhanced reactivity of cysteine-166 with 5,5'-dithiobis(2-nitrobenzoate), which is characteristic of the closed form of the enzyme, with no enhancement of reactivity in the presence of substrates. This is taken to show that the deletion mutant adopts a conformation that is significantly different from that of the mature enzyme particularly in respect of the small domain. The deletion mutant was found to be more resistant to thermal inactivation over a range of temperatures than were the other forms of the enzyme consistent with its having a more tightly packed small domain.

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

    Science.gov (United States)

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

    2013-10-14

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

  12. kinetics

    Directory of Open Access Journals (Sweden)

    D. E. Panayotounakos

    2002-01-01

    Full Text Available We present the construction of the general solutions concerning the one-dimensional (1D fully dynamic nonlinear partial differential equations (PDEs, for the erosion kinetics. After an uncoupling procedure of the above mentioned equations a second–order nonlinear PDE of the Monge type governing the porosity is derived, the general solution of which is constructed in the sense that a full complement of arbitrary functions (as many as the order is introduced. Afterwards, we specify the above solution according to convenient initial conditions.

  13. Characterization and Thermal Dehydration Kinetics of Highly Crystalline Mcallisterite, Synthesized at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Emek Moroydor Derun

    2014-01-01

    Full Text Available The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH62·9(H2O mineral at low temperatures was characterized. For this purpose, several reaction temperatures (0–70°C and reaction times (30–240 min were studied. Synthesized minerals were subjected to X-ray diffraction (XRD, fourier transform infrared (FT-IR, and Raman spectroscopies and scanning electron microscopy (SEM. Additionally, experimental analyses of boron trioxide (B2O3 content and reaction yields were performed. Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA were used for the determination of thermal dehydration kinetics. According to the XRD results, mcallisterite, which has a powder diffraction file (pdf number of “01-070-1902,” was formed under certain reaction parameters. Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30 min of reaction time, particle size was between 398.30 and 700.06 nm. Its B2O3 content and reaction yield were 50.80±1.12% and 85.80±0.61%, respectively. Finally, average activation energies (conversion values (α that were selected between 0.1 and 0.6 were calculated as 100.40 kJ/mol and 98.31 kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS methods, respectively.

  14. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-05

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

  16. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...... in the combustion chamber and the cyclone was calculated taking three mechanisms into account: Reduction by char, catalytic decomposition over bed material and thermal decomposition. The calculated destruction rate was in good agreement with the measured destruction of N2O injected at different levels in the boiler...

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

    Directory of Open Access Journals (Sweden)

    R. Saravanan

    2015-09-01

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

  18. Kinetic Alfven Waves and the Depletion of the Thermal Population in Extragalactic Jets

    Science.gov (United States)

    Jafelice, L. C.; Opher, R.

    1990-11-01

    evident that both problems are intimately related to one another. Jafe- lice and Opher (1987a)(Astrophys. Space Sci. 137, 303)showed that an abundant generation of kinetic Alfven waves (KAw) within EJ and ERS is expected. In the present work we study the chain of processes: a) KAW accelerate thermal electrons along the background magnetic field producing suprathermal runaway electrons; b) which generate Langmuir waves and c) which in turn further accelerate a fraction of the runaway electrons to moderately relativistic energies. We show that assuming that there is no other source of a thermal population but the original one, the above sequence of processes can account for the consumption of thermal electrons in a time scale the source lifetime. Key o : GALAXIES-JETS - HYDROMAGNETICS

  19. 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...

  20. Decomposition kinetics of alkaline earth carbonates by integral approximation method Cinética de decomposição de carbonatos de terra alcalina pelo método de aproximação integral

    Directory of Open Access Journals (Sweden)

    S. Maitra

    2008-09-01

    Full Text Available The decomposition kinetics of four synthetic alkaline earth metal carbonates (MgCO3, CaCO3, SrCO3 and BaCO3 was studied under non-isothermal conditions from thermo-gravimetric measurements as compared to. The integral approximation method of Coats and Redfern was used to determine the kinetic parameters for the decomposition processes. The decomposition reactions followed mostly first order kinetics and the activation energy of the decomposition reactions increased with the increase in the molecular mass of the carbonates. The change in enthalpy for the decomposition processes was also calculated and compared with the activation energies for the decomposition processes. The activation energy of the decomposition process for all the carbonates was higher than the enthalpy of the reaction excepting SrCO3.A cinética de decomposição de quatro carbonatos sintéticos de metais de terra alcalina (MgCO3, CaCO3, SrCO3 e BaCO3 foi estudada sob condições não isotérmicas por meio de medidas de termogravimétricas e feita sua comparação. O método de aproximação integral de Coats e Redfern foi usado para determinar os parâmetros cinéticos dos processos de decomposição. As reações de decomposição seguiram principalmente cinética de primeira ordem e a energia de ativação para as reações de decomposição aumentou com o aumento da massa molecular dos carbonatos. A variação na entalpia para os processos de decomposição foi também calculada e comparada com as energias de ativação. A energia de ativação dos processos de decomposição de todos os carbonatos foi maior que a entalpia da reação excepto para SrCO3.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-25

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

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

    Science.gov (United States)

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

    2015-06-01

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

  3. Comparative Analysis of Thermal Behavior, Isothermal Crystallization Kinetics and Polymorphism of Palm Oil Fractions

    Directory of Open Access Journals (Sweden)

    Bing Li

    2013-01-01

    Full Text Available Thermal behavior of palm stearin (PS and palm olein (PO was explored by monitoring peak temperature transitions by differential scanning calorimetry (DSC. The fatty acid composition (FAC, isothermal crystallization kinetics studied by pulsed Nuclear Magnetic Resonance (pNMR and isothermal microstructure were also compared. The results indicated that the fatty acid composition had an important influence on the crystallization process. PS and PO both exhibited more multiple endotherms than exotherms which showed irregular peak shapes. An increasing in cooling rate, generally, was associated with an increase in peak size. Application of the Avaimi equation to isothermal crystallization of PS and PO revealed different nucleation and growth mechanisms based on the Avrami exponents. PS quickly reached the end of crystallization because of more saturated triacylglycerol (TAG. The Avrami index of PS were the same as PO under the same isothermal condition at lower temperatrue, indicating that the crystallization mechanism of the two samples based on super-cooling state were the same. According to the polarized light microscope (PLM images, crystal morphology of PS and PO was different. With the temperature increased, the structure of crystal network of both PS and PO gradually loosened.

  4. Unusual kinetics of thermal decay of dim-light photoreceptors in vertebrate vision.

    Science.gov (United States)

    Guo, Ying; Sekharan, Sivakumar; Liu, Jian; Batista, Victor S; Tully, John C; Yan, Elsa C Y

    2014-07-22

    We present measurements of rate constants for thermal-induced reactions of the 11-cis retinyl chromophore in vertebrate visual pigment rhodopsin, a process that produces noise and limits the sensitivity of vision in dim light. At temperatures of 52.0-64.6 °C, the rate constants fit well to an Arrhenius straight line with, however, an unexpectedly large activation energy of 114 ± 8 kcal/mol, which is much larger than the 60-kcal/mol photoactivation energy at 500 nm. Moreover, we obtain an unprecedentedly large prefactor of 10(72±5) s(-1), which is roughly 60 orders of magnitude larger than typical frequencies of molecular motions! At lower temperatures, the measured Arrhenius parameters become more normal: Ea = 22 ± 2 kcal/mol and Apref = 10(9±1) s(-1) in the range of 37.0-44.5 °C. We present a theoretical framework and supporting calculations that attribute this unusual temperature-dependent kinetics of rhodopsin to a lowering of the reaction barrier at higher temperatures due to entropy-driven partial breakup of the rigid hydrogen-bonding network that hinders the reaction at lower temperatures.

  5. Morphology and non-isothermal crystallization kinetics of CuInS{sub 2} nanocrystals synthesized by solvo-thermal method

    Energy Technology Data Exchange (ETDEWEB)

    Majeed Khan, M.A., E-mail: majeed_phys@yahoo.co.in [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Kumar, Sushil [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055 (India); Alsalhi, M.S. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Department of Physics and Astronomy, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamed, Maqusood [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Alhoshan, Mansour [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Chemical Engineering Department, King Saud University, Riyadh 11451 (Saudi Arabia); Alrokayan, Salman A. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamad, Tansir [Department of Chemistry, King Saud University, Riyadh 11451 (Saudi Arabia)

    2012-03-15

    Nanocrystals of copper indium disulphide (CuInS{sub 2}) were synthesized by a solvo-thermal method. The structure, morphology and non-isothermal crystallization kinetic behavior of samples were investigated using X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, thermogravimetric analysis and differential thermal analysis techniques. Non-isothermal measurements at different heating rates were carried out and the crystallization kinetics of samples were analyzed using the most reliable non-isothermal kinetic methods. The kinetic parameters such as glass transition temperature, thermal stability, activation energy, Avrami exponent etc. were evaluated. - Highlights: Black-Right-Pointing-Pointer CuInS{sub 2} nanocrystals have scientific and technological importance. Black-Right-Pointing-Pointer Samples have been prepared by solvo-thermal method. Black-Right-Pointing-Pointer Synthesized samples exhibit excellent morphology and thermal properties. Black-Right-Pointing-Pointer Investigated properties may be utilized in design and fabrication of solar cell devices.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-05-01

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

  7. 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.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-15

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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-15

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

  12. An integrated fingerprinting and kinetic approach to accelerated shelf-life testing of chemical changes in thermally treated carrot puree.

    Science.gov (United States)

    Kebede, Biniam T; Grauwet, Tara; Magpusao, Johannes; Palmers, Stijn; Michiels, Chris; Hendrickx, Marc; Loey, Ann Van

    2015-07-15

    To have a better understanding of chemical reactions during shelf-life, an integrated analytical and engineering toolbox: "fingerprinting-kinetics" was used. As a case study, a thermally sterilised carrot puree was selected. Sterilised purees were stored at four storage temperatures as a function of time. Fingerprinting enabled selection of volatiles clearly changing during shelf-life. Only these volatiles were identified and studied further. Next, kinetic modelling was performed to investigate the suitability of these volatiles as quality indices (markers) for accelerated shelf-life testing (ASLT). Fingerprinting enabled selection of terpenoids, phenylpropanoids, fatty acid derivatives, Strecker aldehydes and sulphur compounds as volatiles clearly changing during shelf-life. The amount of Strecker aldehydes increased during storage, whereas the rest of the volatiles decreased. Out of the volatiles, based on the applied kinetic modelling, myristicin, α-terpinolene, β-pinene, α-terpineol and octanal were identified as potential markers for ASLT. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Indian Academy of Sciences (India)

    WINTEC

    LiBOB) were studied using TG (thermogravimetry)-DTG (derivative thermogravimetry) method with different heating rate β of 5, 10, 20 and ... ion chemistry, it still has many disadvantages. For example, it is difficult to dissolve in .... tained using linear regression analysis technique: ln(β′/T. 2 m) = 9⋅61 – 11054⋅56/Tm (r ...

  14. Development of Effective Algorithm for Coupled Thermal-Hydraulics – Neutron-Kinetics Analysis of Reactivity Transient

    OpenAIRE

    Peltonen, Joanna

    2009-01-01

    Analyses of nuclear reactor safety have increasingly required coupling of full three dimensional neutron kinetics (NK) core models with system transient thermal-hydraulics (TH) codes. To produce results within a reasonable computing time, the coupled codes use different spatial description of the reactor core. The TH code uses few, typically 5 to 20 TH channels, which represent the core. The NK code uses explicit node for each fuel assembly. Therefore, a spatial mapping of coarse grid TH and ...

  15. Transient analysis in the 3D nodal kinetics and thermal-hydraulics ANDES/COBRA coupled system

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, Juan Andres; Aragones, Jose Maria; Garcia-Herranz, Nuria [Universidad Politecnica de Madrid, Madrid (Spain)

    2008-07-01

    Neutron kinetics has been implemented in the 3D nodal solver ANDES, which has been coupled to the core thermal-hydraulics (TH) code COBRA-III for core transient analysis. The purpose of this work is, first, to discuss and test the ability of the kinetics solver ANDES to model transients; and second, by means of a systematic analysis, including alternate kinetics schemes, time step size, nodal size, neutron energy groups and spectrum, to serve as a basis for the development of more accurate and efficient neutronics/thermal-hydraulics tools for general transient simulations. The PWR MOX/UO{sub 2} transient benchmark provided by the OECD/NEA and US NRC was selected for these goals. The obtained ANDES/COBRA-III results were consistent with other solutions to the benchmark; the differences in the TH feedback led to slight differences in the core power evolution, whereas very good agreements were found in the other requested parameters. The performed systematic analysis highlighted the optimum kinetics iterative scheme, and showed that neutronics spatial discretization effects have stronger influence than time discretization effects, in the semi-implicit scheme adopted, on the numerical solution. On the other hand, the number of energy groups has an important influence on the transient evolution, whereas the assumption of using the prompt neutron spectrum for delayed neutrons is acceptable as it leads to small relative errors. (authors)

  16. Exploring the Potential of Fulvalene Dimetals as Platforms for Molecular Solar Thermal Energy Storage: Computations, Syntheses, Structures, Kinetics, and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Borjesson, K; Coso, D; Gray, V; Grossman, JC; Guan, JQ; Harris, CB; Hertkorn, N; Hou, ZR; Kanai, Y; Lee, D; Lomont, JP; Majumdar, A; Meier, SK; Moth-Poulsen, K; Myrabo, RL; Nguyen, SC; Segalman, RA; Srinivasan, V; Tolman, WB; Vinokurov, N; Vollhardt, KPC; Weidman, TW

    2014-10-03

    A study of the scope and limitations of varying the ligand framework around the dinuclear core of FvRu(2) in its function as a molecular solar thermal energy storage framework is presented. It includes DFT calculations probing the effect of substituents, other metals, and CO exchange for other ligands on Delta H-storage. Experimentally, the system is shown to be robust in as much as it tolerates a number of variations, except for the identity of the metal and certain substitution patterns. Failures include 1,1',3,3'-tetra-tert-butyl (4), 1,2,2',3'-tetraphenyl (9), diiron (28), diosmium (24), mixed iron-ruthenium (27), dimolybdenum (29), and di-tungsten (30) derivatives. An extensive screen of potential catalysts for the thermal reversal identified AgNO3-SiO2 as a good candidate, although catalyst decomposition remains a challenge.

  17. Exploring the potential of fulvalene dimetals as platforms for molecular solar thermal energy storage: computations, syntheses, structures, kinetics, and catalysis.

    Science.gov (United States)

    Börjesson, Karl; Ćoso, Dušan; Gray, Victor; Grossman, Jeffrey C; Guan, Jingqi; Harris, Charles B; Hertkorn, Norbert; Hou, Zongrui; Kanai, Yosuke; Lee, Donghwa; Lomont, Justin P; Majumdar, Arun; Meier, Steven K; Moth-Poulsen, Kasper; Myrabo, Randy L; Nguyen, Son C; Segalman, Rachel A; Srinivasan, Varadharajan; Tolman, Willam B; Vinokurov, Nikolai; Vollhardt, K Peter C; Weidman, Timothy W

    2014-11-17

    A study of the scope and limitations of varying the ligand framework around the dinuclear core of FvRu2 in its function as a molecular solar thermal energy storage framework is presented. It includes DFT calculations probing the effect of substituents, other metals, and CO exchange for other ligands on ΔHstorage . Experimentally, the system is shown to be robust in as much as it tolerates a number of variations, except for the identity of the metal and certain substitution patterns. Failures include 1,1',3,3'-tetra-tert-butyl (4), 1,2,2',3'-tetraphenyl (9), diiron (28), diosmium (24), mixed iron-ruthenium (27), dimolybdenum (29), and ditungsten (30) derivatives. An extensive screen of potential catalysts for the thermal reversal identified AgNO3 -SiO2 as a good candidate, although catalyst decomposition remains a challenge. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

    Science.gov (United States)

    Bozkurt, Hayriye; Davidson, P. Michael

    2015-01-01

    Human noroviruses (HNoV) and hepatitis A virus (HAV) have been implicated in outbreaks linked to the consumption of presliced ready-to-eat deli meats. The objectives of this research were to determine the thermal inactivation kinetics of HNoV surrogates (murine norovirus 1 [MNV-1] and feline calicivirus strain F9 [FCV-F9]) and HAV in turkey deli meat, compare first-order and Weibull models to describe the data, and calculate Arrhenius activation energy values for each model. The D (decimal reduction time) values in the temperature range of 50 to 72°C calculated from the first-order model were 0.1 ± 0.0 to 9.9 ± 3.9 min for FCV-F9, 0.2 ± 0.0 to 21.0 ± 0.8 min for MNV-1, and 1.0 ± 0.1 to 42.0 ± 5.6 min for HAV. Using the Weibull model, the tD = 1 (time to destroy 1 log) values for FCV-F9, MNV-1, and HAV at the same temperatures ranged from 0.1 ± 0.0 to 11.9 ± 5.1 min, from 0.3 ± 0.1 to 17.8 ± 1.8 min, and from 0.6 ± 0.3 to 25.9 ± 3.7 min, respectively. The z (thermal resistance) values for FCV-F9, MNV-1, and HAV were 11.3 ± 2.1°C, 11.0 ± 1.6°C, and 13.4 ± 2.6°C, respectively, using the Weibull model. The z values using the first-order model were 11.9 ± 1.0°C, 10.9 ± 1.3°C, and 12.8 ± 1.7°C for FCV-F9, MNV-1, and HAV, respectively. For the Weibull model, estimated activation energies for FCV-F9, MNV-1, and HAV were 214 ± 28, 242 ± 36, and 154 ± 19 kJ/mole, respectively, while the calculated activation energies for the first-order model were 181 ± 16, 196 ± 5, and 167 ± 9 kJ/mole, respectively. Precise information on the thermal inactivation of HNoV surrogates and HAV in turkey deli meat was generated. This provided calculations of parameters for more-reliable thermal processes to inactivate viruses in contaminated presliced ready-to-eat deli meats and thus to reduce the risk of foodborne illness outbreaks. PMID:25956775

  19. Decomposition kinetics of gaseous ozone in peanuts Cinética da decomposição do gás ozônio em amendoim

    Directory of Open Access Journals (Sweden)

    Ernandes R. de Alencar

    2011-10-01

    Full Text Available This study was conducted to evaluate the decomposition kinetics of gaseous ozone in peanut grains. This evaluation was made with 1-kg peanut samples, moisture contents being 7.1 and 10.5% wet basis (w.b., placed in 3-liter glass containers. The peanut grains were ozonated at the concentration of 450 µg L-1, at 25 and 35 ºC, with gas flow rates of 1.0 and 3.0 L min-1. Time of saturation was determined by quantifying the residual concentration of ozone after the gas passed through the grains to constant mass. The decomposition kinetics of ozone was evaluated after the grain mass was ozone-saturated. For the peanut grains whose moisture content was 7.1% (w.b., at 25 and 35ºC and with flow rates of 1.0 and 3.0 L min-1, the values obtained for time of saturation of gaseous ozone ranged between 173 and 192 min; the concentration of saturation was approximately 260 µg L-1. For the grains whose moisture content was 10.5% (w.b., a higher residual concentration of gaseous ozone was obtained at 25 ºC, that of 190 µg L-1. As regards the half-life of ozone, the highest value obtained was equivalent to 7.7 min for grains ozonated at 25 ºC, while for those with moisture content of 10.5% at 35 ºC, half-life was 3.2 min. In the process of ozone decomposition in peanut grains, temperature was concluded to be the key factor. An increase of 10 ºC in the temperature of the grains results in a decrease of at least 43% in the half-life of ozone.Este trabalho foi desenvolvido com o objetivo de avaliar a cinética de decomposição do ozônio em grãos de amendoim. Para avaliar a cinética de decomposição do gás, utilizaram-se amostras de 1 kg de amendoim, com teores de água de 7,1 e 10,5% base úmida (b.u., acondicionadas em recipientes de vidro com capacidade de 3 L. Os grãos de amendoim foram ozonizados na concentração de 450 µg L-1, nas temperaturas de 25 e 35 ºC, e vazões do gás de 1,0 e 3,0 L min-1. Determinou-se o tempo de satura

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

    Science.gov (United States)

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

    2017-09-20

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

  1. Distribution Kinetics of Plastics Decomposition

    National Research Council Canada - National Science Library

    小寺, 洋一; J. McCoy, Benjamin

    2003-01-01

    連続分布速度論はマクロ分子混合物成分の分子量分布(または主鎖長)を基にした高分子反応の速度論的解析の方法である。個々の化合物として分離検出が不可能な混合成分に対して分子量分布関数を考え, その増減の収支方程式を立てる。収支方程式からはモーメント値が得られる。高分子の分子量分布の特徴を表すモーメント値は,...

  2. Development of CFD thermal hydraulics and neutron kinetics coupling methodologies for the prediction of local safety parameters for light water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Perez Manes, Jorge

    2013-02-26

    This dissertation contributes to the development of high-fidelity coupled neutron kinetic and thermal hydraulic simulation tools with high resolution of the spatial discretization of the involved domains for the analysis of Light Water Reactors transient scenarios.

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

    Science.gov (United States)

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

    2013-05-09

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

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

    Science.gov (United States)

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

    2015-02-01

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

  5. 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...

  6. Kinetic modelling of thermal inactivation of a keratinase from Purpureocillium lilacinum LPSC # 876 and the influence of some additives on its thermal stability.

    Science.gov (United States)

    Cavello, Ivana A; Cavalitto, Sebastián F

    2014-08-01

    Thermal inactivation of a keratinase produced by Purpureocillium lilacinum LPSC #876 was kinetically investigated using several enzyme inactivation models at the temperature range of 50-65 °C. Among the models studied, the Weibull distribution was the best model that describes the residual activity of P. lilacinum keratinase after heat treatment over the selected temperatures. The stabilising effect of metal ions (Ca2+ or Mg2+, 5 mmol l(-1)) or polyols (propylene glycol and glycerol, 10% v/v) was investigated, showing that the presence of Ca2+ increases the enzyme stability significantly. Conforming to the increased Ca2+ concentration, thermal stability of the enzyme also increased, with 10 mM of Ca2+ being the concentration of metal in which the enzyme retained 100% of its original activity after being incubated for 1 h at 55 °C. The effects of temperature on Weibull equation parameters and on the characteristics of the inactivation curves were evaluated. In the absence of any additives (control), the reliable time (t R) of the keratinase, analogous to D value, ranged from 484.16 to 63.67 min, while in the presence of Ca2+ the t R values ranged from 6,221 to 414.95 min at 50-65 °C. P. lilacinum keratinase is a potentially useful biocatalyst, and therefore, kinetic modelling of thermal inactivation addresses an important topic for its application in various industrial processes.

  7. 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.

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

    Science.gov (United States)

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

    2017-01-01

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

  9. 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.

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

    Science.gov (United States)

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

    2014-08-08

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

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

    Science.gov (United States)

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

    2017-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-09-01

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

  13. Exobase properties of hydrodynamic and kinetic models of thermal escape from planetary atmospheres and notion of slow hydrodynamic escape

    Science.gov (United States)

    Volkov, Alexey N.

    2017-12-01

    Exobase parameters obtained based on one-dimensional spherically symmetric hydrodynamic Parker's and kinetic models of thermal escape are studied parametrically for monatomic and diatomic gases. For source parameters, when Parker's and kinetic models predict similar escape rates and atmospheric structures well below the exobase, the exobase parameters obtained based on the both models are different. Parker's model systematically underestimates the exobase distance and overestimates the exobase Jeans parameter. The assumption that the escape rate is equal to the Jeans escape rate at the exobase is not satisfied in both kinetic and hydrodynamic simulations. The ratio of the escape rate to the Jeans rate at the exobase predicted by the hydrodynamics model can be either a few times higher or orders of magnitude smaller than unity. The kinetic model predicts systematic enhancement of the escape rate compared to the Jeans rate at the exobase. This enhancement can be attributed to the bulk velocity only if the exobase Jeans parameter is smaller than 5. This is the domain of slow hydrodynamic escape. At larger exobase Jeans parameters, the enhancement of the escape rate is attributed to non-equilibrium distribution of molecular velocities. In the kinetic solutions obtained for the Maxwell gas, the escape rate is about 2-2.5 of the Jeans rate when the ratio of the mean free path of gas molecules to the atmospheric scale height is ˜0.2. This finding can be used to set up boundary conditions in the hydrodynamic model in order to bring it into agreement with the kinetic model.

  14. First observation of the thermal Sunyaev-Zel'dovich effect with kinetic inductance detectors

    Science.gov (United States)

    Adam, R.; Comis, B.; Macías-Pérez, J. F.; Adane, A.; Ade, P.; André, P.; Beelen, A.; Belier, B.; Benoît, A.; Bideaud, A.; Billot, N.; Boudou, N.; Bourrion, O.; Calvo, M.; Catalano, A.; Coiffard, G.; D'Addabbo, A.; Désert, F.-X.; Doyle, S.; Goupy, J.; Kramer, C.; Leclercq, S.; Martino, J.; Mauskopf, P.; Mayet, F.; Monfardini, A.; Pajot, F.; Pascale, E.; Perotto, L.; Pointecouteau, E.; Ponthieu, N.; Revéret, V.; Rodriguez, L.; Savini, G.; Schuster, K.; Sievers, A.; Tucker, C.; Zylka, R.

    2014-09-01

    Context. Clusters of galaxies provide valuable information on the evolution of the Universe and large scale structures. Recent cluster observations via the thermal Sunyaev-Zel'dovich (tSZ) effect have proven to be a powerful tool to detect and study them. In this context, high resolution tSZ observations (~tens of arcsec) are of particular interest to probe intermediate and high redshift clusters. Aims: Observations of the tSZ effect will be carried out with the millimeter dual-band NIKA2 camera, based on kinetic inductance detectors (KIDs) to be installed at the IRAM 30-m telescope in 2015. To demonstrate the potential of such an instrument, we present tSZ observations with the NIKA camera prototype, consisting of two arrays of 132 and 224 detectors that observe at 140 and 240 GHz with a 18.5 and 12.5 arcsec angular resolution, respectively. Methods: The cluster RX J1347.5-1145 was observed simultaneously at 140 and 240 GHz. We used a spectral decorrelation technique to remove the atmospheric noise and obtain a map of the cluster at 140 GHz. The efficiency of this procedure has been characterized through realistic simulations of the observations. Results: The observed 140 GHz map presents a decrement at the cluster position consistent with the tSZ nature of the signal. We used this map to study the pressure distribution of the cluster by fitting a gNFW model to the data. Subtracting this model from the map, we confirm that RX J1347.5-1145 is an ongoing merger, which confirms and complements previous tSZ and X-ray observations. Conclusions: For the first time, we demonstrate the tSZ capability of KID based instruments. The NIKA2 camera with ~5000 detectors and a 6.5 arcmin field of view will be well-suited for in-depth studies of the intra cluster medium in intermediate to high redshifts, which enables the characterization of recently detected clusters by the Planck satellite.

  15. Non-isothermal kinetics of the thermal desorption of mercury from a contaminated soil

    Directory of Open Access Journals (Sweden)

    López, Félix A.

    2014-03-01

    Full Text Available The Almadén mining district (Ciudad Real, Spain was the largest cinnabar (mercury sulphide mine in the world. Its soils have high levels of mercury a consequence of its natural lithology, but often made much worse by its mining history. The present work examines the thermal desorption of two contaminated soils from the Almadén area under non-isothermal conditions in a N2 atmosphere, using differential scanning calorimetry (DSC. DSC was performed at different heating rates between room temperature and 600 °C. Desorption temperatures for different mercury species were determined. The Friedman, Flynn-Wall-Ozawa and Coasts–Redfern methods were employed to determine the reaction kinetics from the DSC data. The activation energy and pre-exponential factor for mercury desorption were calculated.El distrito minero de Almadén (Ciudad Real, España tiene la mayor mina de cinabrio (sulfuro de mercurio del mundo. Sus suelos tienen altos niveles de mercurio como consecuencia de su litología natural, pero a menudo su contenido en mercurio es mucho más alto debido a la historia minera de la zona. Este trabajo examina la desorción térmica de dos suelos contaminados procedentes de Almadén bajo condiciones isotérmicas en atmósfera de N2, empleando calorimetría diferencial de barrido (DSC. La calorimetría se llevó a cabo a diferentes velocidades de calentamiento desde temperatura ambiente hasta 600 °C. Se determinaron las diferentes temperaturas de desorción de las especies de mercurio presentes en los suelos. Para determinar la cinética de reacción a partir de los datos de DSC se utilizaron los métodos de Friedman, Flynn-Wall-Ozawa y Coasts–Redfern. Además se calcularon las energías de activación y los factores pre-exponenciales para la desorción del mercurio.

  16. Length scale effects and multiscale modeling of thermally induced phase transformation kinetics in NiTi SMA

    Science.gov (United States)

    Frantziskonis, George N.; Gur, Sourav

    2017-06-01

    Thermally induced phase transformation in NiTi shape memory alloys (SMAs) shows strong size and shape, collectively termed length scale effects, at the nano to micrometer scales, and that has important implications for the design and use of devices and structures at such scales. This paper, based on a recently developed multiscale model that utilizes molecular dynamics (MDs) simulations at small scales and MD-verified phase field (PhF) simulations at larger scales, reports results on specific length scale effects, i.e. length scale effects in martensite phase fraction (MPF) evolution, transformation temperatures (martensite and austenite start and finish) and in the thermally cyclic transformation between austenitic and martensitic phase. The multiscale study identifies saturation points for length scale effects and studies, for the first time, the length scale effect on the kinetics (i.e. developed internal strains) in the B19‧ phase during phase transformation. The major part of the work addresses small scale single crystals in specific orientations. However, the multiscale method is used in a unique and novel way to indirectly study length scale and grain size effects on evolution kinetics in polycrystalline NiTi, and to compare the simulation results to experiments. The interplay of the grain size and the length scale effect on the thermally induced MPF evolution is also shown in this present study. Finally, the multiscale coupling results are employed to improve phenomenological material models for NiTi SMA.

  17. Kinetic modelling of aflatoxins B1 conversion and validation in corn, rice, and peanut during thermal treatments.

    Science.gov (United States)

    Zhang, Chao; Ma, Yue; Zhao, Xiaoyan; Zeng, Yali; Wang, Fen

    2011-12-01

    A kinetic model of the aflatoxins B1 conversion was plotted and validated successfully in the aflatoxin B1-contaminated rice during thermal treatments. Specifically, the kinetic Model A and Model B of the aflatoxin B1 conversion were plotted based on the differential-scanning calorimetry and thermogravimetric analysis, respectively, with the pure aflatoxin B1. In succession, Model A and Model B were validated in the aflatoxin B1-contaminated corn, rice, and peanut during thermal treatments. Model A successfully simulated the conversion of aflatoxin B1 in the aflatoxin B1-contaminated rice with the correlation coefficients of 0.859 and average-absolute deviation of 6.61. The activation energy and conversion order of the aflatoxin B1 conversion were 89.0kJ/mol and 0.12, respectively. Moreover, the relationships between the conversion degree and time vs temperature were plotted based on Model A. These plots would help to predict the final content of aflatoxin B1 after thermal treatments, and give an instruction to develop a food processing. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    1997-03-01

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

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  20. Extension of apparent devolatilization kinetics from thermally thin to thermally thick particles in zero dimensions for woody biomass

    DEFF Research Database (Denmark)

    Johansen, Joakim M.; Jensen, Peter A.; Glarborg, Peter

    2016-01-01

    This work aims to provide an accurate and simple model, predicting the time dependent devolatilization of woody biomass at conditions (Tgasparticle sizes (... small par-ticles are necessary. The current work divides a given particle size distribution into suitable size cate-gories based on their internal heat transport properties. The devolatilization is described by size category specific rate constants based on a single first order reaction mechanism....... This approach allows for significantly more accurate devolatilization predictions of any particle size distribution to be described by simple kinetic mechanisms and isothermal particle heat balances. Such an approach is easily implemented into most commercial CFD (computationalfluid dynamics) codes without...