scholarly journals Kinetics of heterogeneous methanolysis of sunflower oil with CaO∙ZnO catalyst: Influence of different hydrodynamic conditions

2014 ◽  
Vol 20 (3) ◽  
pp. 425-439 ◽  
Author(s):  
Ivana Lukic ◽  
Zeljka Kesic ◽  
Svetolik Maksimovic ◽  
Miodrag Zdujic ◽  
Jugoslav Krstic ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Rate Constant ◽  
Sunflower Oil ◽  
Reaction Rate ◽  
Catalyst Surface ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Model Parameters ◽  
Pseudo First Order Reaction ◽  
Kinetics Of

The kinetics of heterogeneous methanolysis of sunflower oil was studied at 60?C using mechanochemically synthesized CaO?ZnO as catalyst. Influence of agitation speed, catalyst amount and methanol to oil molar ratio on the rate of reaction was analyzed. The rate of the process depends on the two resistances - mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as the values of the overall triglyceride volumetric mass transfer coefficient, kmt,TG, and the effective pseudo first-order reaction rate constant, k, respectively. These kinetic parameters actually determine the value of the apparent reaction rate constant, kapp, whose change with time is defined with the change of triglyceride (TG) conversion. The kinetic model was proposed and the model parameters determined.

scholarly journals Determination of exothermic batch reactor specific model parameters

2019 ◽  
Vol 292 ◽  
pp. 01063
Author(s):  
Lubomír Macků
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Specific Model ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Model Parameters ◽  
Reactor Model ◽  
First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

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.

The relationship between creatine kinase kinetics and exercise intensity in human forearm is unchanged by age

2000 ◽  
Vol 279 (2) ◽  
pp. E333-E339 ◽  
Author(s):  
A. Horská ◽  
K. W. Fishbein ◽  
J. L. Fleg ◽  
R. G. S. Spencer
Keyword(s):  
Creatine Kinase ◽  
Rate Constant ◽  
Reaction Rate ◽  
Intermittent Exercise ◽  
Statistical Significance ◽  
Maximum Voluntary Contraction ◽  
Reaction Rate Constant ◽  
Flexor Digitorum Profundus ◽  
Resonance Spectroscopy ◽  
Pseudo First Order Reaction

Using31P magnetic resonance spectroscopy, creatine kinase (CK) reaction kinetics was assessed in the forearm flexor digitorum profundus muscle of healthy young ( n = 11, age 34.7 ± 5 yr) and older ( n = 20, age 73.5 ± 8 yr) subjects at rest, intermittent exercise at 20% maximum voluntary contraction (MVC), and 40% MVC. Exercise resulted in a significant increase in the average ratio of inorganic phosphate (Pi) to phosphocreatine (PCr) from resting values of 0.073 ± 0.031 (young) and 0.082 ± 0.037 (older) to 0.268 ± 0.140 (young, P < 0.01) and 0.452 ± 0.387 (older, P < 0.01) at 40% MVC. At 40% MVC, intracellular pH decreased significantly, from resting values of 7.08 ± 0.08 (young) and 7.08 ± 0.11 (older) to 6.84 ± 0.19 (young, P < 0.05) and to 6.75 ± 0.25 (older, P < 0.05). Average values of the pseudo-first-order reaction rate k (PCr→ATP) at rest were 0.07 ± 0.04 s−1 in the young and 0.07 ± 0.03 s−1 in the older group. At both exercise levels, the reaction rate constant increased compared with the resting value, but only the difference between the resting value and the 20% MVC value, which showed an 86% higher reaction rate constant in both groups, reached statistical significance ( P < 0.05). No difference in the reaction rate constant between the young and older groups was observed at either exercise level. As with k (PCr→ATP), the average phosphorus flux through the CK reaction increased during exercise at 20% MVC ( P < 0.05 in the older group) but decreased toward resting values at 40% MVC in both groups. The data in our study suggest that normal aging does not significantly affect the metabolic processes associated with the CK reaction.

Crystallization Kinetics of CaOx in Artificial Urine and in Saline System

2014 ◽  
Vol 881-883 ◽  
pp. 708-711
Author(s):  
Lan Qing Deng ◽  
Jun Fa Xue ◽  
Li Kuan ◽  
Jian Ming Ouyang
Keyword(s):  
Reaction Time ◽  
Calcium Oxalate ◽  
Crystallization Kinetics ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Order ◽  
Reaction Rate Constant ◽  
Artificial Urine ◽  
Kinetics Of

The crystallization kinetics of calcium oxalate (CaOx) was comparatively studied by detecting the change of free Ca2+ ions concentration with the reaction time in artificial urine and in saline system. The dynamics equations of CaOx crystallization was r=kcα, and the average reaction order (α) was 3.3 regardless of the relative suprasaturation degree (RS) of CaOx in the range of RS=10.58~17.53. The average reaction rate constant (κ) was (0.97±0.1)×109 in artificial urine and κ=(3.1±1.8)×109 in saline system, due to the presence of inhibitors to CaOx crystallization in artificial urine.

scholarly journals Kinetics of the sunflower oil ethanolysis using CaO as catalyst

2016 ◽  
Vol 22 (4) ◽  
pp. 409-418 ◽  
Author(s):  
Ana Velickovic ◽  
Jelena Avramovic ◽  
Olivera Stamenkovic ◽  
Vlada Veljkovic
Keyword(s):  
Kinetic Model ◽  
Sunflower Oil ◽  
Reaction Rate Constant ◽  
Ethyl Esters ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
Data Points ◽  
Kinetics Of ◽  
Good Agreement

The ethanolysis of sunflower oil catalyzed by calcium oxide was studied in wider ranges of the reaction conditions: temperature 65-75?C, ethanol-to-oil molar ratio 6:1-18:1 and catalyst loading 10-20% in order to determine the reaction kinetics. The proposed kinetic model of the sunflower oil ethanolysis included the changing and first-order reaction mechanism with respect to triacylglycerols and fatty acid ethyl esters. The kinetic parameters were determined and correlated with the process variables. The Arrhenius equation could be applied to the reaction rate constant with the activation energy of 94.0 kJ/mol. The proposed kinetic model showed a good agreement with the experimental data with the mean relative percentage deviation of ?13% (based on 256 data points).

scholarly journals The Effect of Ingredients Mixing Sequence in Rubber Compounding upon Vulcanization Kinetics of Natural Rubber: An Autocatalytic Model Study

2018 ◽  
Vol 18 (4) ◽  
pp. 709
Author(s):  
Abu Hasan ◽  
Rochmadi Rochmadi ◽  
Hary Sulistyo ◽  
Suharto Honggokusumo
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Model ◽  
Reaction Rate Constant ◽  
Model Study ◽  
Vulcanization Kinetics ◽  
Kinetics Of ◽  
Mixing Sequence

This study examined the effect of ingredients mixing sequence to the vulcanization kinetics of natural rubber. The effects of mixing temperature, vulcanization temperature, and the carbon black type upon the kinetics were also studied by using rheography and an autocatalysis reaction model approach. The results showed that this model is good in providing information on vulcanization reaction kinetics of natural rubber. High vulcanization temperature resulted in high reaction rate constant. The more black carbon mixed at the beginning of the rubber mixing process, the higher reaction rate constant would be. The mixing of carbon black and rubber chemicals mixed into the rubber subsequently resulted in the higher reaction rate constant compared with that of simultaneously.

scholarly journals Kinetics of gibbsite leaching in sodium hydroxide aqueous solution

2002 ◽  
Vol 56 (9) ◽  
pp. 381-385
Author(s):  
Ljubica Pavlovic ◽  
Zagorka Acimovic-Pavlovic ◽  
Ljubisa Andric ◽  
Aurel Prstic
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Sodium Hydroxide ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

In order to study the kinetics and mechanism of the reaction, laboratory leaching was carried out with industrially produced gibbsite ?-Al(OH)3 in aqueous solutions containing an excess of sodium hydroxide. The results obtained reaction temperature, duration and base concentration varied. The basic kinetic parameters were determined from: the reaction rate constant k=8.72?107 exp (-74990/RT) and the process activation energy in the range Ea=72.5-96.81 kJ/mol.

Influence of Reduction Time of SSI on Nitrite Removal from Wastewater

2012 ◽  
Vol 450-451 ◽  
pp. 667-671 ◽  
Author(s):  
Jun Guo Li ◽  
Shou Zhang Li ◽  
Wei Tian
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Direct Reduction ◽  
Nitrate Removal ◽  
Reaction Rate Constant ◽  
Pseudo First Order Reaction ◽  
Reduction Time ◽  
Nitrite Removal ◽  
Apparent Reaction Rate Constant ◽  
Apparent Reaction Rate

Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology of SSI and its removal ability for nitrate from wastewater, the influence of reduction time of SSI on nitrate removal percentage was investigated. Because the specific surface area was impact smartly by the reduction time of SSI, it was suggested that nitrate removal ability of SSI should declined with the increasing of reduction time once the reduction time longer than the optimized reduction time. When the reduction time was t1, nitrate removal percentage reached to the maximum. When the nitrate original concentration was 5mg-N/L, the reaction order was closed to 0.7 and the apparent reaction rate constant was 0.323 to 0.359 h-1. When nitrate original concentration increased to 50 mg-N/L, nitrate removal reaction appeared to be the pseudo-first-order reaction, and the apparent reaction rate constant was 0.314 to 0.248 h-1.

Pyrolysis Modeling in a Woodstove

2008 ◽  
Author(s):  
Rajesh Gupta
Keyword(s):  
Rate Constant ◽  
Empirical Model ◽  
Reaction Rate ◽  
Packed Bed ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pseudo First Order ◽  
Simple Empirical Model

A simple empirical model for predicting the pyrolysis rate of fuel packed bed of a woodstove has been presented. The thermolytic behavior of the fuel bed has been approximated by a pseudo-first order reaction. The reaction rate constant has been determined as function of temperature. The effect of orientation of twigs in the fuel bed arrangement and twig diameter on the reaction rate constant has been analyzed. It has been concluded that the effect of twig orientation is insignificant while the peak magnitude of reaction rate constant increased with increasing twig diameter.

Kinetics of CO2 Absorption in MEA+DETA Blended Amine Solutions

2013 ◽  
Vol 864-867 ◽  
pp. 194-200
Author(s):  
Juan Wen ◽  
Chun Xiu Huo ◽  
Bin Zhang
Keyword(s):  
Activation Energy ◽  
Dynamic Model ◽  
Rate Constant ◽  
Absorption Rate ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Experimental Results ◽  
Kinetics Of ◽  
Amine Solutions

The kinetics of CO2absorption in unloaded aqueous MEA, MDEA, DETA single amine solutions and MEA+DETA blende amine solutions was studied with the amine concentrations of 3.0 kmol/m3and at temperatures ranging between 298K and 338K. A dynamic model of CO2absorption rate on the basis of the static absorption experimental results was established. The reaction rate constant of CO2absorption in blended amine solutions MEA+DETA is , and its activation energy is 32.89KJ/mol.

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