Influence of pH on the Kinetics of Hydration of Tricalcium Silicate

1971 ◽  
Vol 49 (6) ◽  
pp. 833-836 ◽  
Author(s):  
K. G. Mccurdy ◽  
B. P. Erno
Keyword(s):  
Rate Constants ◽  
Tricalcium Silicate ◽  
Langmuir Adsorption Isotherm ◽  
Hydrogen Ion ◽  
Particle Sizes ◽  
Large Excess ◽  
Langmuir Adsorption ◽  
Ion Activity ◽  
Influence Of Ph ◽  
Kinetics Of

An investigation has been made of the influence of pH on the kinetics of hydration of tricalcium silicate in a large excess of water. The rate constants increase with increasing hydrogen ion activity [Formula: see text] in the liquid phase when the [Formula: see text] is low; however, as the [Formula: see text] is increased further the rate constants become independent of the[Formula: see text] The results have been interpreted by proposing that the rate constants are proportional to the hydrogen ion activity adsorbed, [Formula: see text] on the solid surface. The Langmuir adsorption isotherm was used to correlate the hydrogen ion activity on the surface to the hydrogen ion activity in the liquid phase.Several particle sizes of tricalcium silicate were investigated and a surface area effect is indicated.

Effect of pH on the reaction of 1,3-dihydro-1-hydroxy-3-oxo-1,2-benziodoxole with 2-mercaptoethanol, 2-mercaptoethylamine, and glutathione

1970 ◽  
Vol 48 (19) ◽  
pp. 3104-3107 ◽  
Author(s):  
James Leslie
Keyword(s):  
Rate Constants ◽  
Ionic Species ◽  
Second Order ◽  
Hydrogen Ion ◽  
Effect Of Ph ◽  
Order Rate ◽  
Rate Determining Step ◽  
Ion Activity ◽  
Kinetics Of ◽  
Linear Manner

The kinetics of the oxidation of 2-mercaptoethanol, 2-mercaptoethylamine, and glutathione with 1,3-dihydro-1-hydroxy-3-oxo-1,2-benziodoxole (1) have been examined at pH 4–5.6. The reaction is second-order, which can be explained by a rate-determining step involving the reaction of one molecule of the thiol with one molecule of 1. The second-order rate constants vary in a linear manner with the reciprocal of the hydrogen ion activity. The ionic species involved in the reaction are discussed.

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.

scholarly journals A thermometric study on the kinetics of the acid dissolution of aluminium in the presence of Napoleonaea imperialis seeds extract and iodide ions

2018 ◽  
Vol 29 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Habibat Faith Chahul ◽  
Gloria Ihuoma Ndukwe ◽  
David Ogwu Ogwu
Keyword(s):  
Free Energy ◽  
Inhibition Efficiency ◽  
Adsorption Process ◽  
Langmuir Adsorption Isotherm ◽  
Seed Extract ◽  
Considerable Extent ◽  
Acid Dissolution ◽  
Iodide Ions ◽  
Langmuir Adsorption ◽  
Kinetics Of

Abstract The dissolution of aluminum alloy AA 1060 in 0.5 M and 1.0 M HCl was investigated using thermometric measurements. The reaction number of the aluminum coupons varied linearly with the concentration of the acid. Addition of Napoleonaea imperialis seed extract to the dissolving aluminium coupons lowered the reaction number in both concentrations of HCl by inhibiting the dissolution process. The inhibition efficiency of Napoleonaea imperialis seed extract was enhanced to a considerable extent in the presence of iodide ions with the synergistic parameter S > 1. The adsorption of Napoleonaea imperialis extract on the aluminium surface best aligned with the Langmuir adsorption isotherm model. The values of the free energy, ΔGadsfor the adsorption process revealed the process to be spontaneous and physisorptive.

Dissolution kinetics of sepiolite from Eskisehir (Turkey) in hydrochloric and nitric acids

Clay Minerals ◽  
1990 ◽  
Vol 25 (2) ◽  
pp. 207-215 ◽  
Author(s):  
H. Cetisli ◽  
T. Gedikbey
Keyword(s):  
Activation Energy ◽  
Acid Concentration ◽  
Rate Constants ◽  
Reaction Rate ◽  
Dissolution Kinetics ◽  
Particle Sizes ◽  
Initial Particle ◽  
Reaction Rate Constants ◽  
Apparent Activation Energies ◽  
Kinetics Of

AbstractDissolution kinetics of sepiolite from Eskisehir (Turkey) have been investigated at various temperatures and particle sizes using dilute hydrochloric and nitric acids. Dissolution reaction rate constants were calculated and apparent activation energies were dependent on acid concentration. For both acids, apparent activation energy values reached a minimum of ∼11 kcal/mol at an acid concentration of 0·75 M. For the second-order reaction which is independent of the acid concentration, the activation energy was 14·5 kcal/mol for both acids. The reaction rate constants were proportional to the acid concentrations, and inversely proportional to the square-root of the initial particle radii of the sepiolite.

scholarly journals Kinetics of the Reaction between Ni(tetren)2+and Bipyridine

2012 ◽  
Vol 1 (2) ◽  
pp. 39-45
Author(s):  
Lawrence Hugh Kolopajlo ◽  
Nekuma Korey Hollis ◽  
Ian Pendelton
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Substitution Reaction ◽  
Ternary Complex ◽  
Ligand Substitution ◽  
Hydrogen Ion ◽  
Rate Law ◽  
Kinetics Of ◽  
Ligand Substitution Reaction

We report a rate law, rate constants and a mechanism for the ligand substitution reaction between Ni(tetren)2+ and 2, 2'-bipyridine in aqueous solution at 25.0 0C. The rate law is: R = k [Ni(tetren2+)] [bipy]. The data supports a mechanism involving a hydrogen ion assisted pathway in which a ternary complex is not formed.

Heavy meatals removal by a promising locally available aquatic plant, Najas graminea Del., in Taiwan

1999 ◽  
Vol 39 (10-11) ◽  
pp. 177-181 ◽  
Author(s):  
Chon-Lin Lee ◽  
Tsen C. Wang ◽  
Ching-Ku Lin ◽  
Hin-Kiu Mok
Keyword(s):  
Aquatic Plant ◽  
Adsorption Process ◽  
Lead Concentration ◽  
Langmuir Adsorption Isotherm ◽  
Competitive Effect ◽  
Langmuir Adsorption ◽  
Kinetics Of ◽  
Copper Lead ◽  
Plating Wastewater ◽  
Nickel Adsorption

This study uses an aquatic plant, Najas graminea Del., to treat man-made wastewater containing single and/or binary components of copper, lead, cadmium and nickel. Adsorption experiments demonstrate that the adsorption process correspond to the Lagergren kinetic model with the rate constant close to 0.01 min−1; meanwhile, the equilibrium results corresponds to the Langmuir adsorption isotherm. Notably, the rate constants of metals are not significantly different between each other. Competitive effect on the adsorption kinetics of cadmium is insignificant with the background solute (lead) concentration up to 10 mg/l; while significant deviation observed with concentration of lead reached 100 mg/l. In addition, the maximum adsorption density of cadmium is reduced by around 50% in the presence of 100 mg/l of lead. A simulated copper plating wastewater is also treated by Najas graminea Del. to demonstrate its efficiency in removing metals from wastewater with multi-cations/anions.

Influence of Surface Area Variation on the Kinetics of Hydration of Tricalcium Silicate

1972 ◽  
Vol 50 (5) ◽  
pp. 701-706 ◽  
Author(s):  
K. G. McCurdy ◽  
B. P. Erno
Keyword(s):  
Surface Area ◽  
Rate Constants ◽  
Initial Step ◽  
Total Surface Area ◽  
Tricalcium Silicate ◽  
Hydration Process ◽  
Kinetic Investigation ◽  
First Order ◽  
Area Variation ◽  
Kinetics Of

Tricalcium silicate reacts initially with aqueous solutions according to a rate law that is first order with respect to the mass of the solid. A kinetic investigation of the hydration of tricalcium silicate for fixed solid to solution, w/w, ratio has been conducted using samples of tricalcium silicate of different total surface area to volume ratios. Consideration of the pH independent rate constants indicates that the rate for the initial step in the hydration process is proportional to the surface area of the solid. Subsequent pH independent rate constants in the overall hydration process are surface area independent.

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.

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

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