A description of chemical and diffusion control in isothermal kinetics of cure kinetics

The kinetics of oxidation with oxygen of chalcocite, Cu2S, to CuS in buffered aqueous ammonia at pH 10.5 at 30� can be modeled approximately by a shrinking core of Cu2S within a thickening shell of CuxS (x ≥ 1). The Cu2S core offers partial cathodic protection to the CuxS and diffusion of Cu+ through CuxS controls the rate of reaction. The kinetics of oxidation of covellite, CuS, to Cu2+, sulfur and sulfate ions in the same solvent can be modeled by a shrinking core of CuS surrounded by a shrinking sphere of CuyS (y < 1) which is much less effectively protected cathodically by the CuS core. Oxidation of CuS is subject to mixed chemical and diffusion control. Rates of oxidation of NiS and of CuS, in the presence and absence of tetrachloroethene and ammonium sulfate, show that, whether sulfur is a major oxidation product or not, the presence of sulfur has very little, if any, influence on the rate or mechanism of oxidation. This is contrary to current ideas on metal sulfide oxidation.

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Steric hindrance effects on dielectric relaxation and polymerization kinetics of a monoamine-triepoxide mixture, thermochemistry, and diffusion control

Journal of Polymer Science Part B Polymer Physics ◽

10.1002/(sici)1099-0488(19981115)36:15<2703::aid-polb4>3.0.co;2-y ◽

1998 ◽

Vol 36 (15) ◽

pp. 2703-2716 ◽

Cited By ~ 6

Author(s):

D. A. Wasylyshyn ◽

G. P. Johari

Keyword(s):

Dielectric Relaxation ◽

Steric Hindrance ◽

Polymerization Kinetics ◽

Diffusion Control ◽

Kinetics Of ◽

And Diffusion

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Nitridation Isothermal Kinetics of In Situ β-Sialon Bonded Al2O3-C Refractories

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.697.572 ◽

2016 ◽

Vol 697 ◽

pp. 572-575

Author(s):

Xue Qing Yang ◽

Nai Peng ◽

Cheng Ji Deng

Keyword(s):

Activation Energy ◽

Apparent Activation Energy ◽

Isothermal Kinetics ◽

Nitridation Reaction ◽

Result Show ◽

Different Temperatures ◽

Two Stages ◽

Kinetics Of ◽

And Diffusion

The kinetics of in-situ β- Sialon bonded Al2O3-C (SAC) refractories were investigated by TGA techniques via isothermal nitridation experiments at different temperatures. The result show that the nitridation process of in-situ β-Sialon bonded Al2O3-C refractories can be divided into two stages: the nitridation reaction rate controlling stage in the first 10 min, and the apparent activation energy of nitridation reaction is 370 kJ/mol ; then the reaction is controlled by both chemical reaction and diffusion rate in the following 110 min, the apparent activation energy of nitridation reaction is 410 kJ/mol.

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Transport properties of nitrile and carbonate solutions of [P66614][NTf2] ionic liquid, its thermal degradation and non-isothermal kinetics of decomposition

Physical Chemistry Chemical Physics ◽

10.1039/d1cp03549e ◽

2021 ◽

Author(s):

Ekaterina A. Arkhipova ◽

Anthon Ivanov ◽

Sergei S. Reshetko ◽

Dmitry Y Aleshin ◽

Konstantin Igorevich Maslakov ◽

...

Keyword(s):

Electrical Conductivity ◽

Ionic Liquid ◽

Thermal Degradation ◽

Diffusion Coefficients ◽

Isothermal Kinetics ◽

Binary Solutions ◽

Kinetics Of Decomposition ◽

Carbonate Solutions ◽

Kinetics Of ◽

And Diffusion

The electrical conductivity, density and diffusion coefficients of trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)amide ([P66614][NTf2]) ionic liquid and its binary solutions in acetonitrile, propionitrile, dimethyl and diethyl carbonates were measured in the temperature range...

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Investigation of Curing Kinetics of Azo-Containing Twin Liquid Crystalline Epoxy Resins with Anhydride

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.702.115 ◽

2013 ◽

Vol 702 ◽

pp. 115-118

Author(s):

Teng Fei Shen ◽

Chun Feng Sun ◽

Ying Juan Sun

Keyword(s):

Epoxy Resins ◽

Liquid Crystalline ◽

Curing Kinetics ◽

Chemical Kinetic ◽

Diffusion Control ◽

Kinetic Control ◽

Control Mechanisms ◽

Scanning Calorimetry ◽

Kinetics Of ◽

And Diffusion

A series of novel azo-containing twin liquid crystalline (LC) epoxy monomers were cured with anhydrides without extra catalyst and the curing kinetics was investigated by non-isothermal differential scanning calorimetry (DSC) technique. The results showed that the effect of phase behavior on activation energy (Ea) was very great. The chemical kinetic control and diffusion control mechanisms dominant the curing together, which gives a larger value of Ea. Azo group also served as a catalyst to accelerate the curing reaction.

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Simultaneous diffusion and chemical activation control of the kinetics of the binding of carbon monoxide to ferroprotoporphyrin IX in glycerol–water mixtures of high viscosity

Canadian Journal of Chemistry ◽

10.1139/v77-561 ◽

1977 ◽

Vol 55 (23) ◽

pp. 3955-3960 ◽

Cited By ~ 7

Author(s):

Brian B. Hasinoff

Keyword(s):

Diffusion Rate ◽

Chemical Activation ◽

High Viscosity ◽

Diffusion Control ◽

Glycerol Water ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion ◽

Simultaneous Influence ◽

Diffusion Controlled Reaction

The kinetics of the reaction of ferroprotoporphyrin IX with CO have been studied in mixed glycerol–water solvents of high viscosity in order that the simultaneous influence of chemical activation and diffusion control of the reaction might be observed. Analyses of curved Arrhenius plots indicated that in the low temperature high viscosity limits the reaction is largely diffusion controlled. The deviation of the second order diffusion rate constants, from that predicted by simple theory for reaction between uniformly reactive spheres of equal radii, is a factor of 0.3 to 0.9, depending upon the solvent composition. A couple of other models for diffusion controlled reaction, ascribing these deviations to changes of steric requirements, were also examined.

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Kinetic Modeling of Essential Oil Extraction by Hydrodistillation of Xylopia aethiopica (Dunal) A. Rich Fruits from Congo-Brazzaville

European Journal of Biology and Biotechnology ◽

10.24018/ejbio.2021.2.3.120 ◽

2021 ◽

Vol 2 (3) ◽

pp. 105-110

Author(s):

Thomas Silou ◽

Jean Bruno Bassiloua ◽

Rosalie Kama Niamayoua

Keyword(s):

Experimental Data ◽

Essential Oil ◽

Diffusion Control ◽

First Order ◽

Extraction Solvent ◽

Peleg Model ◽

Congo Brazzaville ◽

Kinetics Of ◽

And Diffusion ◽

Xylopia Aethiopica

The extraction kinetics of the essential oil of Xylopia aethiopica (Dunal) A. Rich by hydrodistillation was studied for modeling its process and optimizing its yield. The oils obtained, analyzed by GC/MS, consists mainly of pinenes, sabinene, myrenal, terpinene-4-ol, limonene. Experimental data were fitted into first and second order kinetics for a 2-steps extraction, washing and diffusion, of the phenomenological model, according to the hypothesis used. The essential oil which moves inner vegetable cells by diffusion and is extracted at the surface of the particle by washing with an extraction solvent. When the washing step is instantaneous compared to that of diffusion, the mechanism, which is under diffusion control, admits first order. Considering both washing and diffusion steps, kinetic order became 2, in agreement with the Peleg model. The Monod and Langmuir models also fitted experimental data. All these models validated by the experimental data with determination coefficients R2> 0.96 can be used for optimizing the extraction of the essential oil of Xylopia aethiopica (Dunal) A. Rich.

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