Modelling the kinetics of UV/H2O2 oxidation of dichloroacetic acid

2007 ◽  
Vol 55 (12) ◽  
pp. 31-35 ◽  
Author(s):  
C.S. Zalazar ◽  
M.D. Labas ◽  
M.E. Lovato ◽  
R.J. Brandi ◽  
A.E. Cassano
Keyword(s):  
Mathematical Model ◽  
Kinetic Parameters ◽  
Dichloroacetic Acid ◽  
H2o2 Concentration ◽  
Kinetic Measurements ◽  
Theoretical Predictions ◽  
Laboratory Operation ◽  
H2o2 Oxidation ◽  
Intrinsic Kinetic ◽  
Kinetics Of

The intrinsic reaction kinetics of the decomposition of dichloroacetic acid (DCA) using UV/H2O2 was studied. A complete mathematical model, including the effect of the absorbed radiation intensities and H2O2 concentration was developed. The results of the kinetic measurements were analysed using a complete mathematical model of the experimental device that was used for the laboratory operation (a differential reactor inside a recycle). In this way it was expected to obtain intrinsic kinetic parameters. Experimental data agree well with theoretical predictions esmploying just two kinetic parameters derived from the proposed reaction mechanism.

Isothermal DSC study of the curing kinetics of an epoxy/silica composite for microelectronics

2016 ◽  
Vol 2016 (1) ◽  
pp. 000415-000420 ◽  
Author(s):  
Lérys Granado ◽  
Stefan Kempa ◽  
Stefanie Bremmert ◽  
Laurence J. Gregoriades ◽  
Frank Brüning ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Kinetic Method ◽  
Base Material ◽  
Curing Kinetics ◽  
Degree Of Conversion ◽  
Circuit Board ◽  
Heat Of Reaction ◽  
Kinetic Measurements ◽  
Model Free ◽  
Kinetics Of

Abstract Curing kinetics of an industrially important printed-circuit board (PCB) base material (epoxy-phenol/glass fillers) were studied from isothermal differential scanning calorimetry (DSC) measurements between 150 and 190 °C. The extent of cure was calculated by integration of the exothermic peak and normalization by the total heat of reaction (obtained by non-isothermal DSC). The kinetic profiles show two regimes: one fast, and one slower. The completion was reached above 180 °C. The kinetic parameters have been elucidated using an isoconversional model-free kinetic method. The linearity of Arrhenius plots was satisfactory. The apparent activation energy of curing reaction has been found to increase with the degree of conversion. The elucidation of the kinetic parameters allows us to propose an accurate and predictive description of the curing kinetics of the composite until a degree of conversion of 50%. Finally, we discuss how these kinetic measurements and models can be completed and optimized.

Chemical Kinetics Parameter Estimation for Ammonia Borane Hydrolysis

2008 ◽  
Author(s):  
Sumit Basu ◽  
Yuan Zheng ◽  
Jay P. Gore
Keyword(s):  
Parameter Estimation ◽  
Hydrogen Storage ◽  
Kinetic Parameters ◽  
Chemical Kinetics ◽  
Ammonia Borane ◽  
Passenger Cars ◽  
Heterogeneous Chemical Reaction ◽  
Kinetic Measurements ◽  
Linear Fitting ◽  
Intrinsic Kinetic

Onboard hydrogen storage is an enabling factor in the development of fuel cell powered passenger cars. Ammonia borane (AB) hydrolysis is one of the potential technologies for onboard hydrogen storage. In this study, kinetics of catalyzed ammonia borane hydrolysis using ruthenium-supported-on-carbon has been measured. For reacting flows, chemical kinetics determines the rates of heat generation and species production or consumption in the overall energy and mass balances respectively. Kinetic measurements under isothermal conditions provide critical data for the design of hydrolysis reactors. It is, however, not always possible to eliminate the effects of internal diffusion in a heterogeneous chemical reaction. In such cases, the reaction efficiency (η), which depends on the effective liquid phase diffusivity (Deff) in the catalyst medium, should be determined. Determination of intrinsic kinetic parameters using apparent kinetics data is, thus, a challenge. In this study, the change in AB concentration (CAB) with reaction time (t) has been directly measured. It was observed that the AB hydrolysis reaction had orders between zero and one in a temperature range of 26°C to 55°C. A unified Langmuir-Hinshelwood (LH) model has been adopted to describe the reaction kinetics. The intrinsic kinetic parameters (A, Ea, ΔHads, K0) as well as Deff need to be estimated by inverse analysis of the measured CAB vs t data. Conventionally, kinetic parameters are determined using linear fitting. Sometimes, however, it is impossible to converge to a unique value by using the linear fitting approach as there are several values providing regression coefficients greater than 0.99. In this study, the multiple-variable inverse problem has been solved using a nonlinear fitting algorithm based on Powell’s conjugate-gradient error minimization. This algorithm minimizes errors without using derivatives. As a result, the uncertainties in the kinetic parameter estimation have been significantly reduced by the new approach.

Isothermal DSC Study of the Curing Kinetics of an Epoxy/Silica Composite for Microelectronics

2017 ◽  
Vol 14 (2) ◽  
pp. 45-50 ◽  
Author(s):  
Lérys Granado ◽  
Stefan Kempa ◽  
Stefanie Bremmert ◽  
Laurence J. Gregoriades ◽  
Frank Brüning ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Kinetic Method ◽  
Base Material ◽  
Curing Kinetics ◽  
Circuit Board ◽  
Heat Of Reaction ◽  
Scanning Calorimetry ◽  
Kinetic Measurements ◽  
Model Free ◽  
Kinetics Of

Abstract Curing kinetics of an industrially important printed-circuit board (PCB) base material (epoxy–phenol/glass fillers) were studied by isothermal differential scanning calorimetry (DSC) measurements between 150 and 190°C, as relevant curing temperatures for the PCB industry. The extent of cure was calculated by integration of the exothermic peak and normalization by the total heat of reaction (obtained by nonisothermal DSC). Although the cross-linking was completed above 180°C, the kinetic profiles show two regimes: one fast and one slow. The kinetic parameters have been elucidated using an isoconversional model-free kinetic method, with the exact method of Friedman, to give to the PCB manufacturers a road map to predict curing behavior of base material. The linearity of Arrhenius plots was satisfactory. The apparent activation energy of curing reaction has been found to increase with the degree of conversion. The elucidation of the kinetic parameters allows us to propose an accurate and predictive description of the curing kinetics within the fast regimen of reaction (i.e., without vitrification). Finally, we discuss how these kinetic measurements and models can be completed and optimized.

scholarly journals Development of a Mathematical Model for Kinetics of Obtaining Isocyanate via a Non-Phosgene Method for Example Benzylisocyanate

2020 ◽  
Vol 8 (4) ◽  
pp. 1491-1497
Keyword(s):  
Activation Energy ◽  
Mathematical Model ◽  
Kinetic Parameters ◽  
Kinetics Of

The paper considers theprocess of developing a mathematicalmodel for kineticsof obtainingisocyanates via a non-phosgene method non-catalytic thermolysis of carbamates. A mathematical model is presented, kinetic parameters such as activation energy and a pre—exponential multiplier are ascertained.

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

1983 ◽  
Vol 48 (12) ◽  
pp. 3340-3355 ◽  
Author(s):  
Pavel Fott ◽  
Pavel Šebesta
Keyword(s):  
Carbon Dioxide ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thin Layer ◽  
Kinetic Parameters ◽  
Diffusion Region ◽  
Reaction Heat ◽  
Gaseous Products ◽  
Temperature Programmed ◽  
Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

Kinetics of bumetanide-sensitive Na+-K+ co-transport in erythrocytes of essential hypertensive patients

1985 ◽  
Vol 69 (5) ◽  
pp. 607-611 ◽  
Author(s):  
Pietro Delva ◽  
Mario De Gasperi ◽  
Maurizio Degan ◽  
Grazia Covi ◽  
Alessandro Lechi
Keyword(s):  
Kinetic Parameters ◽  
Transport System ◽  
Clinical Data ◽  
Laboratory Data ◽  
Cation Transport ◽  
Hypertensive Patients ◽  
Apparent Affinity ◽  
Normotensive Subjects ◽  
Kinetics Of

1. Outward bumetanide-sensitive Na+-K+ co-transport was studied in the erythrocytes of 51 subjects, 24 normotensive subjects and 27 hypertensive patients, matched for sex and age. 2. Three kinetic parameters of this cation transport system were considered: velocity of efflux at saturating internal sodium (Nai) concentrations (Vmax.), apparent affinity for sodium (K50%) and index of co-operativity among Nai sites (Hill's n). 3. We correlated these values with clinical and laboratory data determined routinely in hypertension. 4. There were no significant differences between normotensive and hypertensive subjects for the values considered and we did not find any significant correlations between co-transport and clinical data.

scholarly journals Determining the mass-related reaction effectiveness factor of large, nonspherical fuel particles for bridging between intrinsic and apparent combustion kinetics

2019 ◽  
Vol 141 (2) ◽  
pp. 797-806 ◽  
Author(s):  
Tibor Szűcs ◽  
Pal Szentannai
Keyword(s):  
Combustion Process ◽  
Effectiveness Factor ◽  
Cfd Modeling ◽  
Combustion Kinetics ◽  
Kinetic Measurements ◽  
Environmental Requirements ◽  
Fuel Particles ◽  
Related Reaction ◽  
Kinetics Of ◽  
Internal Pore

AbstractThe utilization of challenging solid fuels in the energy industry is urged by environmental requirements. The combustion kinetics of these fuel particles differs markedly from that of pulverized coal, mainly because of their larger sizes, irregular (nonspherical) shapes, and versatile internal pore structures. Although the intrinsic reaction kinetic measurements on very small amounts of finely ground samples of these particles are mostly available, a bridge toward their apparent reaction modeling is not evident. In this study, a method is introduced to build this bridge, the goodness of which was proved on the example of an industrially relevant biofuel. To do this, the results of a macroscopic combustion measurement with real samples in a well-modelable environment have to be used, and for considering some not negligible effects, 3D CFD modeling of the experimental environment is also to be applied. The outcome is the mass-related reaction effectiveness factor as a function of the rate of conversion. This variable can be considered as the active fraction of the entire particle mass on its periphery, and it can be used as the crucial element in modeling the combustion process of the same particle under other circumstances by including the actual boundary conditions. Another advantage of this method is its covering inherently the entire combustion process (water and volatile release, and char combustion) and also its applicability for reactors utilizing bigger particles like fluidized bed combustors.

scholarly journals Kinetic measurements of the biliary excretion of metabolized compounds

1980 ◽  
Vol 188 (2) ◽  
pp. 561-564
Author(s):  
G M Powell ◽  
J G Jones ◽  
C G Curtis
Keyword(s):  
Kinetic Parameters ◽  
Cholic Acid ◽  
Biliary Excretion ◽  
Kinetic Measurements

1. Rats received constant infusions of bromosulphophthalein or [carboxy-14C]cholic acid at a range of concentrations. 2. Kinetic parameters describing the biliary excretion of the compounds were determined. 3. The biliary excretion of both compounds could be described by the same kinetic parameters already calculated for phenolphthalein disulphate, which is excreted in the bile unchanged.

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