THE RADIOLYSIS OF ETHANOL: II. BINARY VAPOR MIXTURES

1961 ◽  
Vol 39 (9) ◽  
pp. 1843-1847
Author(s):  
J. M. Ramaradhya ◽  
G. R. Freeman
Keyword(s):  
Experimental Data ◽  
Kinetic Parameters ◽  
Vapor Phase ◽  
Reaction Mechanisms ◽  
Marked Decrease ◽  
Hydrogen Yield ◽  
Hydrogen Atoms ◽  
Energy Excitation ◽  
Straight Line ◽  
Vapor Mixtures

Benzene and cyclohexene cause a marked decrease in the hydrogen yield from the vapor phase radiolysis of ethanol.The experimental data were tested against the two reaction mechanisms that gave straight-line plots for the corresponding cyclohexane–protector systems. Both of these mechanisms also gave straight-line plots for the ethanol–protector systems.One mechanism involved scavenging of hydrogen atoms. The values of the kinetic parameters derived from this mechanism are quite similar in the cyclohexane and ethanol systems.The second mechanism involved the transfer of energy (excitation or ionization) from ethanol to the protector. The values of the kinetic parameters derived from this mechanism showed some differences between the ethanol and cyclohexane systems.One possible reason for the lack of resolution between the two reaction mechanisms might be that they both occur to comparable extents. Two mechanisms appear to occur to comparable extents in the liquid cyclohexane system.

THE RADIOLYSIS OF CYCLOHEXANE: IV. BINARY MIXTURES IN THE VAPOR PHASE

1961 ◽  
Vol 39 (9) ◽  
pp. 1769-1775 ◽  
Author(s):  
J. M. Ramaradhya ◽  
G. R. Freeman
Keyword(s):  
Experimental Data ◽  
Reaction Mechanisms ◽  
Excited Molecule ◽  
Hydrogen Yield ◽  
Hydrogen Atoms ◽  
Energy Excitation ◽  
Gaseous Mixtures ◽  
Straight Line ◽  
Positive Ion ◽  
Mechanisms Of Reactions

The variation of the hydrogen yield with the composition of binary gaseous mixtures containing cyclohexane and benzene, cyclohexene, or propylene is qualitatively similar to that in the liquid phase.The quantitative experimental data were tested against several possible reaction mechanisms and two mechanisms gave straight-line plots.One mechanism involved scavenging of hydrogen atoms. The values of the kinetic parameters derived from this mechanism might not be unreasonable in the mixtures of cyclohexane with cyclohexene or propylene. The values for benzene, however, seem less likely.The second mechanism involved the transfer of energy (excitation or ionization) from cyclohexane to the second substance. The values of the ratio of the rate constants, k7/k6, of the reactions[Formula: see text]is about 103 times greater in the gas than in the liquid phase. Consideration of possible detailed mechanisms of reactions [6] and [7] indicates that this difference is reasonable if C6H12** is a positive ion rather than an excited molecule.

The Vapor Phase Radiolysis of Isopropanol and Water–Isopropanol Mixtures. II. Nitrous Oxide as Electron Scavenger

1971 ◽  
Vol 49 (17) ◽  
pp. 2909-2912 ◽  
Author(s):  
M. G. Bailey ◽  
R. S. Dixon
Keyword(s):  
Nitrous Oxide ◽  
Vapor Phase ◽  
Electron Attachment ◽  
Hydrogen Yield ◽  
Reactive Intermediate ◽  
Secondary Species ◽  
Electron Yield ◽  
Electron Scavenger ◽  
Vapor Mixtures ◽  
Reaction With Water

Nitrous oxide reduces the hydrogen yield from water–isopropanol vapor mixtures by complete scavenging of electrons. Nitrogen is produced over the whole concentration range but the yield at higher isopropanol concentrations is much greater than the electron yield. The results indicate a competition between water and isopropanol for a secondary species resulting from electron attachment to N2O. Reaction of this species with isoprooanol leads to further N2 whereas reaction with water does not. The reactive intermediate is most probably N2O− or N2O2−.

Radiolysis of methylcyclohexane. III. Pure vapor phase and effects of additives

1967 ◽  
Vol 45 (14) ◽  
pp. 1649-1659 ◽  
Author(s):  
W. J. Holtslander ◽  
G. R. Freeman
Keyword(s):  
Vapor Phase ◽  
Secondary Reaction ◽  
Hydrogen Yield ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Hydrogen Formation ◽  
Positive Ions ◽  
Total Ionization ◽  
Different Types ◽  
Increasing Temperature

The radiolysis of methylcyclohexene (MCH) vapor was carried out under a variety of conditions. The G-values of the main products at 110°, extrapolated to zero dose, are hydrogen (5.2), methylcyclohexene isomers (2.0), ethylene (1.5), methane (1.3), propylene (0.8), and total dimer (0.3). Other products were also measured.The hydrogen yield was reduced to G = 3.1 by each of the additives, N2O, SF6, and CCL4, and to G = 1.6 by C2H4. Both DI and ND3 increased the total hydrogen yield above the value in pure MCH. In pure MCH approximately 50% of the ions (G(total ionization) = 4.4) resulted in hydrogen formation, whereas in the presence of DI or ND3, 75% of the ions are hydrogen precursors. Thus three different types of positive ions are distinguished in the system: G(M1+) = 2.1, G(M2+) = 1.3, and G(N+) = 1.0.The average ion lifetime with respect to neutralization was 10−3 s. The ion DI−was therefore stable with respect to decomposition to D + I− for a period greater than 10–3 s under the conditions of the experiments (~380 Torr MCH, 110°).The yield of methylcyclohexene isomers increased with increasing temperature and increased upon addition of ND3 or C2H4 to the radiolysis system. The dimer yield was also enhanced by the addition of ND3. This effect was explained by the occurrence of an ionic secondary reaction that destroys methylcyclohexene and (or) methylcyclohexyl radicals in pure MCH.Approximately 85% of the methane is produced by methyl radicals abstracting hydrogen atoms from MCH.

The Acetone – Acetic Anhydride – Carbon Disulfide System: Surface Tension, Viscosity, and Total and Partial Vapor Pressures

1971 ◽  
Vol 49 (13) ◽  
pp. 2183-2192 ◽  
Author(s):  
A. N. Campbell ◽  
E. M. Kartzmark ◽  
S. C. Anand
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Acetic Anhydride ◽  
Carbon Disulfide ◽  
Vapor Phase ◽  
The Other ◽  
Vapor Pressures ◽  
Free Energies ◽  
Vapor State ◽  
Straight Line

The surface tensions, viscosities, and vapor pressures, total and partial, have been determined as functions of concentration for the following systems: (a) acetone – acetic anhydride; (b) acetone – carbon disulfide; (c) acetic anhydride – carbon disulfide; and (d) pseudo-binary mixtures of (a) and (b), whose compositions lie on a straight line tangential to the plait point of the ternary system.The general behavior of ideal and non-ideal systems, in regard to surface tension and viscosity is discussed. For the system acetone – carbon disulfide, whose vapor phase can be considered ideal, the activities, activity coefficients, excess free energies, enthalpies and entropies of mixing have been obtained from the vapor pressures. The vapor phase of the other three systems contains acetic anhydride which is associated in the vapor state, and for these systems the experimental data are reported without further calculation.

Kinetic parameters estimation in an anaerobic digestion process using successive quadratic programming

2005 ◽  
Vol 52 (1-2) ◽  
pp. 419-426 ◽  
Author(s):  
C.A. Aceves-Lara ◽  
E. Aguilar-Garnica ◽  
V. Alcaraz-González ◽  
O. González-Reynoso ◽  
J.P. Steyer ◽  
...  
Keyword(s):  
Experimental Data ◽  
Anaerobic Digestion ◽  
Quadratic Programming ◽  
Kinetic Parameters ◽  
Parameters Estimation ◽  
Fixed Bed Reactor ◽  
Accurate Estimation ◽  
Successive Quadratic Programming ◽  
Anaerobic Digestion Process ◽  
Digestion Process

In this work, an optimization method is implemented in an anaerobic digestion model to estimate its kinetic parameters and yield coefficients. This method combines the use of advanced state estimation schemes and powerful nonlinear programming techniques to yield fast and accurate estimates of the aforementioned parameters. In this method, we first implement an asymptotic observer to provide estimates of the non-measured variables (such as biomass concentration) and good guesses for the initial conditions of the parameter estimation algorithm. These results are then used by the successive quadratic programming (SQP) technique to calculate the kinetic parameters and yield coefficients of the anaerobic digestion process. The model, provided with the estimated parameters, is tested with experimental data from a pilot-scale fixed bed reactor treating raw industrial wine distillery wastewater. It is shown that SQP reaches a fast and accurate estimation of the kinetic parameters despite highly noise corrupted experimental data and time varying inputs variables. A statistical analysis is also performed to validate the combined estimation method. Finally, a comparison between the proposed method and the traditional Marquardt technique shows that both yield similar results; however, the calculation time of the traditional technique is considerable higher than that of the proposed method.

The Kinetics of Austenization Process of T91 Ferritic Heat-Resistant Steel

2011 ◽  
Vol 317-319 ◽  
pp. 42-47
Author(s):  
Li Fang Zhang ◽  
Yong Chang Liu
Keyword(s):  
Experimental Data ◽  
Phase Transformation ◽  
Kinetic Parameters ◽  
Nucleation And Growth ◽  
Transformation Model ◽  
Resistant Steel ◽  
Kinetic Characteristics ◽  
Heat Resistant Steel ◽  
Austenite Grain ◽  
Kinetics Of

By fitting the calculated transformed fraction according to developed phase-transformation model to the experimental data obtained by differential dilatometry, the kinetic characteristics of the austenitization process in T91 steels have been investigated. According to the kinetic parameters fitted, we recognize that the nucleation and growth of austenite grain are mainly controlled by the diffusion of carbon in ferritic and austenite respectively. In addition, by increasing the diffusion active energy of carbon in austenite, carbides hinder the motion of interface and thus refine austenite grain.

scholarly journals Thermal Degradation Behaviour of Ni(II) Complex of 3,4-Methylenedioxaphenylaminoglyoxime

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Emin Karapınar ◽  
Ilkay Hilal Gubbuk ◽  
Bilge Taner ◽  
Pervin Deveci ◽  
Emine Ozcan
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermal Degradation ◽  
Metal Complex ◽  
Kinetic Parameters ◽  
Preexponential Factor ◽  
Degradation Behaviour ◽  
Mechanism Of Decomposition ◽  
Pyrolytic Decomposition

Thermal degradation behaviour of the Ni(II) complex of 3,4-methylenedioxaphenylaminoglyoxime was investigated by TG, DTA, and DTG at a heating rate of 10°C min−1under dinitrogen. The acquired experimental data shows that the complex is thermally stable up to 541 K. The pyrolytic decomposition process occurs by melting metal complex and metal oxide remains as final product. The energies of the reactions involved and the mechanism of decomposition at each stage have been examined. The values of kinetic parameters such as activation energy (E), preexponential factor (A) and thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) are also evaluated.

scholarly journals AN INNOVATE METHOD OF THERMOGRAVIMETRIC DATA ANALYSIS

2021 ◽  
Vol 64 (3) ◽  
pp. 24-32
Author(s):  
Mihail V. Mal’ko ◽  
Sergej V. Vasilevich ◽  
Andrey V. Mitrofanov ◽  
Vadim E. Mizonov
Keyword(s):  
Experimental Data ◽  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Kinetic Parameters ◽  
Calculation Method ◽  
Kinetic Calculation ◽  
Pyrolysis Mechanism ◽  
Total Mass Loss ◽  
Thermogravimetric Data ◽  
Heavy Tar

The objective of the study is to examine the Coats-Redfern approximation and to propose an innovative kinetic calculation method for the complex process of the heavy tar thermal decomposition under non-isothermal process. The thermal decomposition process was examined using the thermogravimetric analysis. There are several kinetic models proposed to analyze pyrolysis mechanism in terms of the formal reaction. In this manner, the kinetic parameters of the pyrolysis process can be evaluated based on total mass loss (thermogravimetric analysis –TGA). The TGA procedures can be conducted with isothermal or non-isothermal conditions, but the experimental data obtained according to this procedure have to be transformed into appropriate correlation. The obtained results have shown that the reaction takes place within temperature range of 540 K to 700 K and the inductive period of the process is about 224 min. Kinetic parameters were estimated with using of the conventional Coats-Redfern method. A new kinetic calculation method has been designed to provide a less laboriousness of identifications procedures compared with Coats-Redfern approximation and to take into account an induction time of the process. As the outcome of this study, it was shown that the kinetic parameters estimated with using of the proposed model-fitted method gives the more appropriate correlation in comparison with the conventional Coats-Redfern method. The proposed method uses the Coats-Redfern algorithm for evaluation of the reaction mechanism, but the value of the constant rate is defined directly from experimental data on the conversion rate.

γ-Radiolysis of cyclohexane with electron scavengers. VI. N2O and SF6 as electron scavengers in the vapor phase

1968 ◽  
Vol 46 (22) ◽  
pp. 3511-3516 ◽  
Author(s):  
N. H. Sagert ◽  
R. W. Robinson ◽  
A. S. Blair
Keyword(s):  
Carbon Dioxide ◽  
Vapor Phase ◽  
General Mechanism ◽  
Hydrogen Yield ◽  
Neutral Species ◽  
First Order ◽  
Nitrogen Yield

The γ-radiolysis of cyclohexane has been examined in the vapor phase using N2O and SF6 as electron scavengers. Both N2O and SF6 reduce the hydrogen yield from 4.6 to 3.0 G units, indicating that 3.0 G units of hydrogen have neutral species as precursors, while 1.6 G units have electrons as precursors.Radiolysis of cyclohexane vapor with more than 2% N2O produces 10.4 G units of cyclohexene and 11.5 of nitrogen. Carbon dioxide reduces both these yields; the extrapolated value of G(N2) is equal to G(electrons) at infinite CO2 concentration. Thus O− is likely a precursor of that part of the nitrogen yield in excess of G(electrons), and of the cyclohexene yield associated with this nitrogen yield.The first order molecular detachment of hydrogen is unaffected by electron scavengers, showing that most of this first order yield has neutral precursors. The implications for Dyne's general mechanism of hydrocarbon radiolysis are discussed.

RADIATION CHEMISTRY OF CYCLOHEXANE: VI. DILUTE SOLUTIONS OF CARBON TETRACHLORIDE AND CHLOROFORM IN CYCLOHEXANE

1964 ◽  
Vol 42 (3) ◽  
pp. 669-681 ◽  
Author(s):  
J. A. Stone ◽  
P. J. Dyne
Keyword(s):  
Carbon Tetrachloride ◽  
Chemical Reaction ◽  
Physical Process ◽  
Radical Scavenging ◽  
Radiation Chemistry ◽  
Hydrogen Yield ◽  
Halogenated Compounds ◽  
Dilute Solutions ◽  
Hydrogen Atoms

A study of the effect of the addition of small amounts (<3.5%) of the halogenated compounds CCl4, CHCl3, and CDCl3 on the radiolysis of cyclohexane has shown that processes other than radical scavenging occur. At the lowest concentrations of solute that it was practical to employ (0.004 M) cyclohexyl radicals were scavenged without a corresponding reduction in the hydrogen yield. At higher solute concentrations G(H2) was reduced by a physical process which did not involve the scavenging of thermal hydrogen atoms but did lead to chemical reaction involving the solute.

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