scholarly journals Buoyancy driven second grade nano boundary layers over a catalytic surface with reaction rate, heat of reaction and activation energy at boundary

2021 ◽  
pp. 101346
Author(s):  
N. Vishnu Ganesh ◽  
R. Kalaivanan ◽  
Qasem M. Al-Mdallal ◽  
K. Reena
Keyword(s):  
Activation Energy ◽  
Boundary Layers ◽  
Reaction Rate ◽  
Second Grade ◽  
Heat Of Reaction ◽  
Catalytic Surface

Zur Theorie der Elektronenübergangsreaktionen in molekularen Komplexen / Theory of Electron Transfer Reactions in Molecular Complexes

1974 ◽  
Vol 29 (6) ◽  
pp. 880-887 ◽  
Author(s):  
P. P. Schmidt
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Charge Transfer ◽  
Rate Constant ◽  
Reaction Rate ◽  
Charge Transfer Complex ◽  
Rate Theory ◽  
Transfer Step ◽  
Donor And Acceptor ◽  
Inner Sphere

This paper reports a theory of the inner sphere-type electron transfer reaction. Inner sphere reactions, as opposed to the outer sphere variety, require that the solvate or ligand shells surrounding the electron donor and acceptor species undergo considerable change in the course of the electron transfer. In this paper we assume that the electron transfer step takes place in a molecular complex which exists in equilibrium with the reactants. The electron transfer step occurs as a non-radiative charge transfer-type transition. In this manner we treat the charge transfer kinetics, in particular, the evaluation of the reaction rate constant, in the same manner as is usual for non-radiative problems. The analysis leading to the rate constant expression is based on Yamamoto’s general chemical reaction rate theory. The rate constant expressions obtained are quite general, they hold for any degree of strength of coupling between subsystems comprising the entire system. The activation energy, in the Arrhenius form for the rate constant, shows a dependence on the energy (work) of formation of the intermediate charge transfer complex, on vibrational shift energies associated with the molecular motions of the ligands, and on solvent repolarization energies. The activation energy also shows an important dependence on coupling terms which link the vibrations of the molecular inner shell with the polarization states of the (assumed) dielectric continuum which surrounds the charge transfer participants. The approach we take in developing this theory we believe points the way towards the development of a more complete theory capable of accounting for the dynamics of the molecular reorganization leading to the intermediate charge transfer complex as well as accounting for the electron transfer step itself.

Kinetic Studies on the Synthesis of Hydroxyapatite Nanowires by Solvothermal Methods

2007 ◽  
Vol 60 (2) ◽  
pp. 99 ◽  
Author(s):  
Shiying Zhang ◽  
Chen Lai ◽  
Kun Wei ◽  
Yingjun Wang
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Axial Ratio ◽  
Reaction Rate Constant ◽  
Rate Equations ◽  
Solvothermal Reaction ◽  
Growth Order ◽  
Constant Diffusion ◽  
Solvothermal Methods

Hydroxyapatite nanowires with a high axial ratio have been synthesized in reverse micelle solutions that consist of cetyltrimethylammonium bromide (CTAB), n-pentanol, cyclohexane, and the reactant solution by solvothermal methods. This paper focusses on the kinetic studies of the solvothermal reaction and the linear growth of hydroxyapatite nanowires. When the reaction was carried out at low temperatures (65°C), the experimental results showed that the reaction rate was of zero order since the whole reaction was diffusion controlled with constant diffusion coefficients. In the middle to high temperature range (130–200°C), the kinetics were characterized by second order reaction kinetics. Since the controlling factor was activation energy and the apparent activation energy was large, the reaction rate was more sensitive to the temperature. Therefore, the exponent of the reaction rate constant increased by two when the temperature was increased from 130 to 200°C. By calculating the yields of products and the specific surface areas at different times, the linear and overall growth rate equations of the hydroxyapatite nanowires could be obtained. The experimental effective growth order of the crystals was 11. The larger growth order indicated that the crystal could grow more effectively in one direction because of the induction of the surfactant in the experiment system.

scholarly journals Microwave-Assisted Transesterification of Kusum Oil: Parametric, Kinetic and Thermodynamic Studies

2020 ◽  
Vol 32 (11) ◽  
pp. 2893-2903
Author(s):  
SHEETAL N. NAYAK ◽  
MILAP G. NAYAK ◽  
CHANDRAKANT P. BHASIN
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Frequency Factor ◽  
Molar Ratio ◽  
Pseudo First Order Reaction ◽  
Time Intervals ◽  
First Order ◽  
Microwave Assisted ◽  
Lower Heat ◽  
Kinetic And Thermodynamic Studies

Microwave-assisted transesterification of non-edible oil to produce biodiesel is gaining attention due to lower heat loss as well as rapid conversion. In this study, esterified kusum oil as a feedstock was transesterified in the presence of Ba(OH)2. At 800 W microwave power and constant magnetic stirring the effect of important process parameters such as solvent methanol molar ratio, Ba(OH)2, temperature, and time on biodiesel yield were evaluated. The parametric study suggested that 9:1 M methanol, 65 ºC reaction temperature, 2.5 wt% Ba(OH)2 catalyst and 3.5 min of transesterification time gave close to 96% biodiesel yield. At the above conditions of methanol and catalyst, the reaction kinetics and thermodynamic study were performed using different time intervals. The microwave-assisted transesterification followed pseudo-first-order reaction rate with 34.57 kJ/mol K activation energy and 205664 min-1 frequency factor. The reduction in activation energy and increase in the frequency factor reveal the non-thermal effect associated with microwave heating. The thermodynamic properties evaluated using the Eyring equation suggests non-spontaneity and endothermic nature of transesterification.

scholarly journals Analysis of the Kinetics of Swimming Pool Water Reaction in Analytical Device Reproducing Its Circulation on a Small Scale

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4820 ◽  
Author(s):  
Wojciech Kaczmarek ◽  
Jarosław Panasiuk ◽  
Szymon Borys ◽  
Aneta Pobudkowska ◽  
Mikołaj Majsterek
Keyword(s):  
Activation Energy ◽  
Water Quality ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Small Scale ◽  
Pool Water ◽  
Swimming Pool Water ◽  
Kinetics Of ◽  
Analytical Device

The most common cause of diseases in swimming pools is the lack of sanitary control of water quality; water may contain microbiological and chemical contaminants. Among the people most at risk of infection are children, pregnant women, and immunocompromised people. The origin of the problem is a need to develop a system that can predict the formation of chlorine water disinfection by-products, such as trihalomethanes (THMs). THMs are volatile organic compounds from the group of alkyl halides, carcinogenic, mutagenic, teratogenic, and bioaccumulating. Long-term exposure, even to low concentrations of THM in water and air, may result in damage to the liver, kidneys, thyroid gland, or nervous system. This article focuses on analysis of the kinetics of swimming pool water reaction in analytical device reproducing its circulation on a small scale. The designed and constructed analytical device is based on the SIMATIC S7-1200 PLC driver of SIEMENS Company. The HMI KPT panel of SIEMENS Company enables monitoring the process and control individual elements of device. Value of the reaction rate constant of free chlorine decomposition gives us qualitative information about water quality, it is also strictly connected to the kinetics of the reaction. Based on the experiment results, the value of reaction rate constant was determined as a linear change of the natural logarithm of free chlorine concentration over time. The experimental value of activation energy based on the directional coefficient is equal to 76.0 [kJ×mol−1]. These results indicate that changing water temperature does not cause any changes in the reaction rate, while it still affects the value of the reaction rate constant. Using the analytical device, it is possible to constantly monitor the values of reaction rate constant and activation energy, which can be used to develop a new way to assess pool water quality.

Homogeneous Catalysis of Hydrogen Isotope Exchange Between D2 and Ethanol by Chlorotris(triphenyIphosphine)rhodium(I). II. In Chloroform-Ethanol

1974 ◽  
Vol 52 (12) ◽  
pp. 2226-2235 ◽  
Author(s):  
Graeme Strathdee ◽  
Russell Given
Keyword(s):  
Activation Energy ◽  
Computer Simulation ◽  
Exchange Reaction ◽  
Homogeneous Catalysis ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Reaction Rate ◽  
Side Reaction ◽  
Rate Determining Step ◽  
Inverse Isotope Effect

The kinetics and mechanism of D2 exchange catalyzed by RhCl(PPh3)3 have been studied in chloroform–ethanol solutions. Interpretation of the results was complicated by a side reaction of the solvent to yield HCl, RhHCl2(PPh3)2, C2H5Cl, CH2Cl2, Ph3PO, and other phosphorus(V) species. Computer simulation of the exchange reaction was used to show that the observed inverse isotope effect [Formula: see text] could arise only if the rate determining step was the activation of D2, HD, and H2 by RhCl(PPh3)3.The D2 exchange reaction rate was extremely dependent on solvent composition and decreased 30 times between 6 and 96 mol% C2H5OH. The activation energy for D2 exchange was 101 ± 9 kJ mol−1 at 58 mol% C2H5OH, and 86 ± 8 kJ mol−1 at 6 mol% C2H5OH. These data suggested that solvent–catalyst bonding interactions were important.

Effect of Heat of Reaction on Temperature Distribution and Acid Penetration in a Fracture

1980 ◽  
Vol 20 (06) ◽  
pp. 501-507 ◽  
Author(s):  
M.H. Lee ◽  
L.D. Roberts
Keyword(s):  
Temperature Distribution ◽  
Thermal Energy ◽  
Balance Equation ◽  
Reaction Rate ◽  
Energy Equation ◽  
Fluid Temperature ◽  
Heat Of Reaction ◽  
Mass Balance Equation ◽  
Acid Rock ◽  
First Time

Abstract In a fracture acidizing treatment the acid reacts with the fracture faces. This acid/rock reaction generates heat that causes the acid temperature itself to increase. To predict accurately the temperature profile and acid spending rate of acid traveling down a hydraulically created fracture, this heat must be considered.Since the heat generated by reaction depends on the reaction rate, the thermal energy equation must be coupled with the acid spending equation. A model has been developed that, for the first time, examines the effect of the heat of reaction on fluid temperature and acid penetration in a fracture. Some sample calculations have also been made to illustrate the effects of the most important parameters on acid penetration in a fracture. Introduction Acid hydraulic fracturing is a common method of stimulating a reservoir. Acid selectively reacts with, and dissolves, portions of the fracture wall so that a finite fluid conductivity remains when the well is returned to production. An important aim in designing such fracturing treatments is determining the distance that live acid will penetrate down the hydraulically induced fracture. This distance is usually called the acid penetration distance and is essential to estimate the production improvement from a given treatment.Because of its importance in predicting stimulation ratio, acid penetration in fractures has been studied by numerous investigators. They assumed the temperature in the fracture was uniform. In real fractures, however, the temperature will vary from the wellbore to the tip of the fracture. Therefore, the assumption of constant temperature seems to be an oversimplification.Whitsitt and Dysart were among the first to study the temperature distribution in a fracture. They constructed a model but it could be applied only to a nonreacting fluid flowing in a fracture because the heat generated by an acid/rock reaction was not considered. In a fracture acidizing treatment, the acid is reacting with the rock walls. This acid/rock reaction generates heat, which causes the acid temperature itself to increase. To predict accurately the temperature profile along the fracture, this heat also must be considered. A model has been developed that, for the first time, examines the effect of the heat of reaction on fluid temperature and acid penetration distance. Mathematical Development The mathematical model is a modification of that introduced by Whitsitt and Dysart to allow for the heat of reaction in the energy-balance equation. Since the heat generated by the acid reaction also depends on the reaction rate, the thermal-energy equation is coupled with the mass-balance equation. These two equations must be solved simultaneously .The model for acid spending in a fractures is illustrated in Fig. 1. The fluid leakoff velocity Vw is assumed constant over the fracture length. Assuming steady-state flow in a vertical fracture and constant fluid properties, the mass-balance equation for acid flowing in a fracture is ................(1) SPEJ P. 501＾

Determination of the reaction rate constant and activation energy for pressure-induced 2+2 cycloaddition of the C60 fullerene

2002 ◽  
Vol 44 (3) ◽  
pp. 557-559 ◽  
Author(s):  
V. A. Davydov ◽  
L. S. Kashevarova ◽  
A. V. Rakhmanina ◽  
V. M. Senyavin ◽  
N. N. Oleinikov ◽  
...  
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
C60 Fullerene
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