The kinetics of hydration of tricalcium silicate

1970 ◽  
Vol 48 (21) ◽  
pp. 3291-3299 ◽  
Author(s):  
K. G. McCurdy ◽  
B. P. Erno
Keyword(s):  
Reaction Mechanism ◽  
Intermediate Product ◽  
Activation Energies ◽  
Tricalcium Silicate ◽  
Rate Data ◽  
Large Excess ◽  
First Order ◽  
Kinetics Of ◽  
Subsequent Decomposition

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.

Re-examination of the kinetics of the thermal dehydroxylation of kaolinite

Clay Minerals ◽  
1984 ◽  
Vol 19 (4) ◽  
pp. 653-661 ◽  
Author(s):  
J. M. Criado ◽  
A. Ortega ◽  
C. Real ◽  
E. Torres De Torres
Keyword(s):  
Reaction Mechanism ◽  
Diffusion Process ◽  
Diffusion Mechanism ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Comparison Of The Results ◽  
Kinetics Of

AbstractThe results obtained from this study of kaolinite dehydroxylation explain why different investigators have ascribed both first-order kinetics and a diffusion mechanism to this reaction. The fact that activation energies reported by these workers agree well, in spite of the different kinetics assumed when performing the calculations, is also explained. From a comparison of the results obtained by isothermal and non-isothermal methods it is concluded that, for reacted fractions,α, <0·6, kaolinite dehydroxylation is controlled by a diffusion process. A reaction mechanism explaining this behaviour is proposed.

THE KINETICS OF THE REACTION OF ORGANIC ISOTHIOCYANATES WITH 1-OCTANOL IN o-DICHLOROBENZENE

1962 ◽  
Vol 40 (12) ◽  
pp. 2369-2375 ◽  
Author(s):  
Yoshio Iwakura ◽  
Hisao Okada
Keyword(s):  
Reaction Mechanism ◽  
Rate Constants ◽  
Catalytic Effect ◽  
Relative Rate ◽  
Slow Step ◽  
Dibutyltin Dilaurate ◽  
Kcal Mole ◽  
Large Excess ◽  
First Order ◽  
Kinetics Of

The kinetics of the reaction of organic isothiocyanates with a large excess of 1-octanol in o-dichlorobenzene was examined at 90–140°. The rate of the reaction was first order with respect to the concentration of isothiocyanate, but the apparent second-order rate constants calculated varied according to the initial 1-octanol concentration. These facts can be explained by a reaction mechanism involving two molecules of 1-octanol in the transition state for the slow step of the reaction. The relative rate of the reaction of isothiocyanates with 1-octanol at 120° decreased in the order of benzyl, phenyl, allyl, ethyl, n-butyl, n-hexyl, isobutyl, and cyclohexyl isothiocyanate. The apparent energies of activation and log A were obtained as 13.5–16.5 kcal/mole and 4.65–6.46 (A in liter/mole min), respectively. Tributylamine had a slight catalytic effect, but dibutyltin dilaurate and ferric acetylacetonate had a strong catalytic action in these reactions.

scholarly journals Kinetics and mechanism of sol-gel transformation between some trivalent- and tetravalent-metal ions and Sodium alginate Anionic polyelectrolyte with formation of coordination Biopolymeric structure polymembranes Hydrogels of Capillary Structures Ex

2007 ◽  
Vol 3 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Ishaq Abdullah Zaafarany
Keyword(s):  
Sodium Alginate ◽  
Metal Ion ◽  
Sol Gel ◽  
Coordination Geometry ◽  
Large Excess ◽  
First Order ◽  
Pseudo First Order ◽  
The Stability ◽  
Kinetics Of ◽  
Overall Kinetics

Abstract          The kinetics of sol-gel transformation between A13+, La 3+ and Th4+ metal ion electrolytes and sodium alginate sol have been studied complexometrically at various  temperatures. In the presence of a large excess of sodium alginate sol concentration over that of metal ion electrolyte, the pseudo first–order plots of exchange showed sigmoidal curves with two distinct stages. The initial part was relatively fast and curved significantly at early times, followed by a slow decrease in the rates of exchange over longer time periods. The rate constants of gelation showed second-order overall kinetics which was first order in the concentration of both reactants. The thermodynamic parameters have been evaluated and tentative gelation mechanisms consistent with the kinetic results of gelation are suggested. The stability of these ionotropic metal-alginate complexes has been discussed in terms of the coordination geometry and strength of chelated bonds.

scholarly journals Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

2015 ◽  
Vol 81 (14) ◽  
pp. 4850-4859 ◽  
Author(s):  
Hayriye Bozkurt ◽  
Doris H. D'Souza ◽  
P. Michael Davidson
Keyword(s):  
Hepatitis A ◽  
Thermal Inactivation ◽  
Hepatitis A Virus ◽  
Weibull Model ◽  
Activation Energies ◽  
Inactivation Kinetics ◽  
Order Model ◽  
Decimal Reduction Time ◽  
First Order ◽  
Kinetics Of

ABSTRACTHuman 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. TheD(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, thetD = 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. Thez(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. Thezvalues 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.

Kinetics and Mechanism of Oxidation of Selenium(IV) by Permanganate Ion in Aqueous Perchlorate Solutions

1993 ◽  
Vol 58 (3) ◽  
pp. 538-546 ◽  
Author(s):  
Refat M. Hassan ◽  
Sahr A. El-Gaiar ◽  
Abd El-Hady M. El-Summan
Keyword(s):  
Reaction Mechanism ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Selenium Dioxide ◽  
Order Reaction ◽  
Acid Solutions ◽  
First Order ◽  
Acid Catalyzed ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

The kinetics of permanganate oxidation of selenium dioxide in perchloric acid solutions at a constant ionic strength of 2.0 mol dm-3 has been investigated spectrophotometrically. A first-order reaction in [MnO4-] and fractional order with respect to selenium(IV) were observed. The reaction rate was found to be pH-independent at lower acid concentrations ([H+] < 0.5 mol dm-3) and was acid-catalyzed beyond this range. Addition of Mn2+ and F- ions leads to the prediction that MnO4- is the sole reactive species in the oxidation process. A tentative reaction mechanism consistent with the reaction kinetics has been proposed.

Kinetics of DeNOx Process by Ammonia Injection

2011 ◽  
Vol 356-360 ◽  
pp. 2131-2135
Author(s):  
Hai Ping Xiao ◽  
Qin Jian Yu ◽  
Lei Huang
Keyword(s):  
Free Radicals ◽  
Reaction Mechanism ◽  
Removal Efficiency ◽  
Intermediate Product ◽  
Reaction Process ◽  
Nox Removal ◽  
Important Intermediate ◽  
Nox Removal Efficiency ◽  
Kinetics Of ◽  
Ammonia Injection

In order to discover reaction mechanism between ammonia and NOx, reaction process of ammonia and NOx was simulated from the point of kinetics. As a result, NOx removal efficiency was kept in 47.23% ~98.89% at 800°C~1000°C. When NH3/NO was equal or less than 1.5, NOx removal efficiency was enhanced obviously with NH3/NO increasing. NH2 was produced as an important intermediate product in NH3 decomposition. Firstly NH2 was formed in reactions between NH3 and free radicals such as OH, H, O, M. Then NO was directly reduced to N2 by NH2.Therefore, free radicals (especially for NH2, O and H) have important influence on removal efficiency of NOx during ammonia injection.

THE REACTION OF 2,2-DIPHENYL-1-PICRYLHYDRAZYL WITH SECONDARY AMINES

1958 ◽  
Vol 36 (12) ◽  
pp. 1729-1734 ◽  
Author(s):  
J. E. Hazell ◽  
K. E. Russell
Keyword(s):  
Secondary Amine ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Major Product ◽  
The Other ◽  
Secondary Amines ◽  
First Order ◽  
Kinetics Of

The reaction of DPPH (2,2-diphenyl-1-picrylhydrazyl) with N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, diphenylamine, and methylaniline has been studied and has been shown to be primarily a hydrogen abstraction process. Two moles DPPH react with 1–1.15 moles secondary amine to give 1.7–1.8 moles 2,2-diphenyl-1-picrylhydrazine and further products.The reaction between DPPH and N-phenyl-1-naphthylamine is first order with respect to each reactant. The reaction of DPPH with the other amines is retarded by the major product 2,2-diphenyl-1-picrylhydrazine and the kinetics of the over-all reaction are complex. However second-order rate constants and activation energies have been obtained using initial rates of reaction. Possible reaction mechanisms are discussed.

Studies on Metal Hydroxy Compounds. XIII. Thermal Analyses and Decomposition Kinetics of Hydroxystannates of Bivalent Metals

1971 ◽  
Vol 49 (17) ◽  
pp. 2813-2816 ◽  
Author(s):  
P. Ramamurthy ◽  
E. A. Secco
Keyword(s):  
Thermal Analyses ◽  
Decomposition Reaction ◽  
Decomposition Kinetics ◽  
Order Reaction ◽  
First Order ◽  
Calorimetric Measurements ◽  
Bivalent Metals ◽  
Hydroxy Compounds ◽  
Kinetics Of ◽  
Subsequent Decomposition

The thermal analyses of hexahydroxystannates of bivalent metals of the type Me[Sn(OH)6], where Me = Zn, Co, Cu, Ni, Mn, Ca, Mg, Cd, Sr, reveal that the primary mode of decomposition occurs by dehydroxylation and subsequent decomposition of the metastannate residue occurs in the Zn, Cu, Mn, Ca, and Mg compounds. Calorimetric measurements along with related enthalpic values for the decomposition reaction are given. The kinetics of thermal decomposition of all compounds studied, except the Cd and Mg analogues, follow first order reaction kinetics up to α ~ 0.9.

scholarly journals Kinetics of Oxidation of Tryptophan by Sodium Hypochlorite

1981 ◽  
Vol 36 (3) ◽  
pp. 359-361 ◽  
Author(s):  
Thomas Rausch ◽  
Frieder Hofmann ◽  
Willy Hilgenberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Sodium Hypochlorite ◽  
Arrhenius Plot ◽  
Ph Dependence ◽  
Order Conditions ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of

AbstractThe oxidation of tryptophan to 3-indoleacetaldehyde with sodium hypochlorite was investigated with 14C labelled DL-tryptophan. The reaction was performed under pseudo first order conditions. From the pH dependence of the reaction it was concluded that only the unprotonated tryptophan is converted to the aldehyde. The activation energy is 35 ± 2.2 (SE) kJ x mol-1 as derived from the Arrhenius plot. Variing the pH between 8.5 and 11.0 and the temperature in the range from 298 K to 318 K did not alter the selectivity of the reaction as confirmed by TLC of the product (purity ≧ 90%). A possible reaction mechanism is proposed.

Influence of the Polarity of the Medium on the Alkaline Hydrolysis of n-Butyl Acetate in Hydroalcoholic Mixtures

1977 ◽  
Vol 32 (5) ◽  
pp. 496-500
Author(s):  
M. S. Celdrán ◽  
M. V. Ramón ◽  
P. Martínez
Keyword(s):  
Reaction Mechanism ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Butyl Acetate ◽  
Activation Energies ◽  
Free Energies ◽  
Kinetics Of ◽  
Hydrolysis Of

Abstract The kinetics of the alkaline hydrolysis of n-butyl acetate have been studied in water and in hydroalcoholic mixtures. The rate constants, activation energies, frequency factors, entropies, Gibbs free energies and enthalpies of activation have been determined. The radii of the activated com­ plexes have been calculated and related to their degree of solvation. A possible reaction mechanism is formulated.

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