Mass transfer in heterogeneous system enzyme-substrate; Kinetic model of enzymatic reaction in system of two immiscible liquids

1982 ◽  
Vol 47 (11) ◽  
pp. 3019-3026 ◽  
Author(s):  
František Kaštánek ◽  
Jindřich Zahradník ◽  
Germanico Ocampo
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Kinetic Model ◽  
Interphase Boundary ◽  
Heterogeneous System ◽  
Enzymatic Reaction ◽  
Reaction Rates ◽  
Immiscible Liquids ◽  
Enzyme Substrate

Mathematical model is proposed enabling calculation of enzymatic reaction rates occuring in one phase of a system of two immiscible liquids under conditions of substrate and product transfer over the interphase boundary.

Mass transfer in heterogeneous system enzyme-substrate; Approximate analytical model for the case of liquid substrate-immobilized enzyme

1982 ◽  
Vol 47 (11) ◽  
pp. 3013-3018
Author(s):  
František Kaštánek ◽  
Jindřich Zahradník ◽  
Germanico Ocampo
Keyword(s):  
Mass Transfer ◽  
Heterogeneous System ◽  
Immobilized Enzyme ◽  
Enzymatic Reaction ◽  
Analytical Form ◽  
Approximate Model ◽  
Basic Type ◽  
Reaction Interface ◽  
Enzyme Substrate ◽  
Flow Intensity

Calculation procedure is suggested for flow intensity of substrate toward reaction interface of immobilized enzyme at simultaneous effect of enzymatic reaction and internal diffusion. The approximate model is presented in an analytical form for the basic type of Michaelis-Menten kinetics and for the case of inhibition in excess of substrate.

The Effect of Surface Kinetics in Fracture Acidizing

1974 ◽  
Vol 14 (04) ◽  
pp. 385-395 ◽  
Author(s):  
L.D. Roberts
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Reaction Rates ◽  
Graphical Form ◽  
Mixing Coefficient ◽  
Acid Reaction ◽  
The Mathematical Model ◽  
Plate System ◽  
Acid Leakoff

Abstract A mathematical model is developed that yields the distance to which live aid may penetrate into a fracture under conditions in which the over-all reaction kinetics. The model is solved by an explicit finite-difference method, and the results are presented in graphical form. An example design presented in graphical form. An example design calculation is given for HC1 reaction in a dolomite fracture. Experimental data are presented for acid flow in limestone and dolomite laboratory - prepared fracture systems 4.1 t 9.7 ft long, at 71, 190, and 290F. From these experiments was determined a parameter appearing in the mathematical model-termed the effective mixing coefficient. The mixing coefficient has a minimum in the low Reynolds number region, indicating that rectilinear laminar flow is approached more closely just before the flow becomes turbulent. The mixing coefficient also appears to be dependent upon temperature in the laminar flow region. The mathematical solutions given in this paper are applicable to situations in which the over-all rate of acid reaction is not determined solely by mass transfer. Introduction Acids are widely used in the hydraulic fracturing of reservoirs to stimulate wells. Roughly speaking, the purpose of the acid is to selectively react with and dissolve portions of the fracture wall so that a finite fluid conductivity remains when the well is returned to production. One important variable that must be known in designing these acid fracturing treatments is the distance to which acid will penetrate the fracture before completely reacting penetrate the fracture before completely reacting and becoming spent. This distance is usually termed the acid penetration length and is an essential part of the information needed for predicting productivity after acidizing. Other important design variables include the dynamic fracture geometry and the residual fracture conductivity. Because of its importance in predicting stimulation ratios, acid penetration into a fracture has been studied by several investigators. Both static tests and dynamic tests have been used to predict acid reaction rates in fractures. It seems predict acid reaction rates in fractures. It seems reasonable that a dynamic acid reactor test will be useful for predicting acid spending rates, since the mass transfer rate in an actual fracture may be approached in this type of test. One experimental apparatus used for acid flow tests in parallel plate system such as that used by Barron et al. plate system such as that used by Barron et al. and by Williams and Nierode. In these tests, acid is pumped at a known flow rate through a fracture of known geometry and the inlet and outlet acid composition is measured. From the resulting information it is possible to predict acid penetration in a real fracture with the aid of a mathematical model having experimentally determined parameters. We present here the results of an investigation of the use of mathematical model for predicting acid spending a fracture. Using Williams and Nierode's approach to calculating acid penetration, we have extended their method to allow for the fact that the surface reaction rates of several acid-rock systems (e.g., HC1-dolomite) may be finite compared with the rate of mass transfer to the surface. Experimental data are presented for determining the parameters appearing in the mathematical model and a sample calculation illustrates its use. MATHEMATICAL MODEL FOR ACID FRACTURING The mathematical model presented here is a modification of that introduced by Williams and Nierode to allow for the occurrence of finite reaction rates. This modification makes it possible to calculate theoretical penetration distances for acid featuring when reaction kinetics are important as in the case of the HC1-dolomite reaction. Since an analytical solution of the model is not possible, a finite-difference method was developed and is presented in Appendix A. presented in Appendix A. The model for acid formula is fracturing is presented in Fig. 1. Here the acid leakoff velocity, presented in Fig. 1. Here the acid leakoff velocity, is assumed constant over the fracture length. SPEJ p. 385

scholarly journals Kinetic analysis of the partial synthesis of artemisinin: Photooxygenation to the intermediate hydroperoxide

2021 ◽  
Author(s):  
S. Triemer ◽  
M. Schulze ◽  
B. Wriedt ◽  
R. Schenkendorf ◽  
D. Ziegenbalg ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Kinetic Model ◽  
Flow Reactor ◽  
Fluid Velocity ◽  
Initial Step ◽  
Reaction Rates ◽  
Photon Flux ◽  
Partial Synthesis ◽  
Two Phase ◽  
Drug Compound

AbstractThe price of the currently best available antimalarial treatment is driven in large part by the limited availability of its base drug compound artemisinin. One approach to reduce the artemisinin cost is to efficiently integrate the partial synthesis of artemisinin starting from its biological precursor dihydroartemisinic acid (DHAA) into the production process. The optimal design of such an integrated process is a complex task that is easier to solve through simulations studies and process modelling. In this article, we present a quantitative kinetic model for the photooxygenation of DHAA to an hydroperoxide, the essential initial step of the partial synthesis to artemisinin. The photooxygenation reactions were studied in a two-phase photo-flow reactor utilizing Taylor flow for enhanced mixing and fast gas-liquid mass transfer. A good agreement of the model and the experimental data was achieved for all combinations of photosensitizer concentration, photon flux, fluid velocity and both liquid and gas phase compositions. Deviations between simulated predictions and measurements for the amount of hydroperoxide formed are 7.1 % on average. Consequently, the identified and parameterized kinetic model is exploited to investigate different behaviors of the reactor under study. In a final step, the kinetic model is utilized to suggest attractive operating windows for future applications of the photooxygenation of DHAA exploiting reaction rates that are not affected by mass transfer limitations.

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

Therapeutic Nanoemulsion: Concept to Delivery

2020 ◽  
Vol 26 (11) ◽  
pp. 1145-1166 ◽  
Author(s):  
Md. A. Barkat ◽  
Harshita ◽  
Md. Rizwanullah ◽  
Faheem H. Pottoo ◽  
Sarwar Beg ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Clinical Practice ◽  
Droplet Size ◽  
Heterogeneous System ◽  
Dosage Form ◽  
Design Development ◽  
Immiscible Liquids

: Nanoemulsions (NEs) or nanometric-scaled emulsions are transparent or translucent, optically isotropic and kinetically stable heterogeneous system of two different immiscible liquids namely, water and oil stabilized with an amphiphilic surfactant having droplet size ranges up to 100 nm. They offer a variety of potential interests for certain applications: improved deep-rooted stability; excellent optical clarity; and, enhanced bioavailability due to its nanoscale of particles. Though there is still comparatively narrow insight apropos design, development, and optimization of NEs, which mainly stems from the fact that conventional characteristics of emulsion development and stabilization only partly apply to NEs. The contemporary article focuses on the nanoemulsion dosage form journey from concept to key application in drug delivery. In addition, industrial scalability of the nanoemulsion, as well as its presence in commercial and clinical practice, are also addressed.

A mathematical model of turbulent heat and mass transfer in stably stratified shear flow

1993 ◽  
Vol 253 (-1) ◽  
pp. 341 ◽  
Author(s):  
G. I. Barenblatt ◽  
M. Bertsch ◽  
R. Dal Passo ◽  
V. M. Prostokishin ◽  
M. Ughi
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Shear Flow ◽  
Heat And Mass Transfer ◽  
Turbulent Heat ◽  
Stratified Shear Flow ◽  
Stably Stratified Shear Flow

scholarly journals Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model

2021 ◽  
Author(s):  
M. Leuchtenmueller ◽  
C. Legerer ◽  
U. Brandner ◽  
J. Antrekowitsch
Keyword(s):  
Mass Transfer ◽  
Zinc Oxide ◽  
Kinetic Model ◽  
Large Scale ◽  
Industrial Wastes ◽  
Oxide Reduction ◽  
Transfer Coefficients ◽  
Metallothermic Reduction ◽  
Metal Bath ◽  
Zinc Recovery

AbstractEffective recycling of zinc-containing industrial wastes, most importantly electric arc furnace dust, is of tremendous importance for the circular economy of the steel and zinc industry. Herein, we propose a comprehensive kinetic model of the combined carbothermic and metallothermic reduction of zinc oxide in a metal bath process. Pyro-metallurgical, large-scale lab experiments of a carbon-saturated iron melt as reduction agent for a molten zinc oxide slag were performed to determine reaction constants and accurately predict mass transfer coefficients of the proposed kinetic model. An experimentally determined kinetic model demonstrates that various reactions run simultaneously during the reduction of zinc oxide and iron oxide. For the investigated slag composition, the temperature-dependent contribution of the metallothermic zinc oxide reduction was between 25 and 50 pct of the overall reaction mechanism. The mass transfer coefficient of the zinc oxide reduction quadrupled from 1400 °C to 1500 °C. The zinc recovery rate was > 99.9 pct in all experiments.

RESEARCH OF CYCLONE CHARACTERISTICS FOR DRY CLEANING OF GASES FROM DUST

2020 ◽  
Vol 5 (3) ◽  
pp. 49-61
Author(s):  
Andrii Cheilytko ◽  
◽  
Sergii Ilin
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Working Conditions ◽  
Ecological Condition ◽  
Air Purification ◽  
Dust Collection ◽  
Dry Cleaning ◽  
Harmful Emissions ◽  
Reduce Emissions ◽  
The Mathematical Model

The development and application of new, more efficient dust collection units that will help reduce emissions and conserve some very valuable resources for production is an important area of research. With the growth of innovation in technological enterprises, the number of harmful emissions into the atmosphere is growing. Thus, the ecological condition of the environment deteriorates. The basic analytical dependences which are necessary for construction of a technique of carrying out experiments and calculations of dust catching for concrete working conditions are developed. Methods of calculating cyclones as vortex devices and research of cyclone operation for air purification from dust were investigated. On the basis of the used basic theoretical positions of heat and mass transfer and thermodynamics at carrying out analytical researches the mathematical model was offered. Calculations of new designs of modern cyclones to obtain their geometric dimensions, resistance and dust capture efficiency were presented. Modern cyclones are designed to more effectively remove dust from the air during various types of work.

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