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# Kinetic Modeling - Science topic

Explore the latest questions and answers in Kinetic Modeling, and find Kinetic Modeling experts.

Questions related to Kinetic Modeling

Hello all,

I am developing a kinetic model for a pseudo-homogeneous first-order reaction system and I intend to optimize rate constants. In this regard, I wanted to know if I can use excel for the same and if yes how to do so.

Any help is welcome and much appreciated.

Earnestly looking for insightful answers.

Thanks and regards

Hello,

I'm looking for some help about the understanding of adsorption kinetics of an adsorbant material (zeolite) towards several chemical pollutants. I saw many papers describing adsorption performance through different kinetics model (Langmuir, Freundlich...) but I am not getting how to model this kinetics onto my data and how to interpret them.

Hoping to be clear enough,

Maurizio

Best regards

I am working on predicting the nutrition requirement for optimum growth of fish. The available model to do that is using the "5-saturation kinetics model curve calculation". However, details of using this method are not available. Any help will be very appreciated.

Thank you

In the published literature, it is well established that only 60% of data can be used to fit Korsmeyer-Peppas model.

What about other models like Zero-order, First order, Higuchi, and Hixson–Crowell.

Hello everyone,

Does anyone have any recommendations on how to calculate a diffusion coefficient from drug release data? I know that I will acquire the drug release over time and with this I can perform a mean least squares test to determine which kinetic model (Korsmeyer-Peppas, ect) is best fitted. This is where I am stuck, how do I get a diffusion coefficient from this kinetic model/data?

This isn't my usual background so I am struggling with this, any help would be greatly appreciated.

Cheers,

Sabrina

Hello! I have a problem with a reformer kinetic implemented in Aspen Plus. I have a PFR reactor that need to be closed with a recycle. In this recycle there is a very small amount of H2 that invalidate the kinetic and gives me error, this is because in the reaction rate expression, some terms are divided for the partial pressure of H2, and therefor being so small, is like dive everything for zero and that is causing problem in the converge.

Is anyone of you familiar with such problem? There is a way to "eliminate" a component from a stream is present below a certain amount?

Thank you

Can First-order kinetic model be applied to experimental data

Kindly suggest the importance of it.

Thank You.

Good morning everyone,

I am studying the adsorption of different proteins on nanoparticles and I would like to plot the Langmuir adsorption isotherm.

The Langmuir equation Ce/Qe=1/(QmK)+Ce/Qe. And the isotherm is represented as Ce/Qe vs Ce.

Contrary to the usual set up for Langmuir adsorption isotherm studies, I have a fixed amount of adsorbate (proteins) and increasing amount of adsorbent (nanoparticles).

How to determine Ce, Qe, and plot the Langmuir isotherm?

Thank you for your help.

Dear all,

I have planned to do kinetic studies of Dry (CO

_{2}) Reforming of Methane experimentally and theoretically for my developed Ni/Ce_{X}-Zr_{1-X}O_{2}. I went through some published papers, and they have shown the final kinetics equation based on different kinetic models, which is very difficult for me to understand and perform for my experiment. May I get help from any one of you in this regard or anybody willing to research collaboration with me in these regard?Thank you in advance for your kind consideration and any valuable supports!

How to examine kinetic modelling, thermodynamic and equilibrium calculations in a degradation/absorption or solubility study using response surface methodology (RSM)? Which RSM models are suitable for this?

Different researchers are testing new sorbent materials using different methods such as the fixed bed column or batch method, and they use several models to support their results, like Langmuir, Yoon–Nelson, (BDST), Thomas, Elovich equation, the pseudo-first-order equation, the pseudo-second-order equation, and others. So which one is suitable and more important to support and examine the results when testing a new sorbent material?

I am doing adsorption isotherm studies. I have carried out kinetic modeling with Ce and qe values. However I am stuck in equilibrium studies. I have conducted the experiment for a run of 24 h, which is my equilibrium study time. How do I get the data for making the graph? Are we supposed to use the same data for Ce and qe for experimental study which we used for kinetic study?

Hello!

Kinetic research in the field of curing process is of great interest for me. It is okay, when some of epoxy resin based systems can be described in terms of usual second (n) order reaction models with additional autocatalysis and/or deceleration terms. Sometime we need to use so called diffusion factor function if reaction is complicated by glass transition temperature and deceleration term in usual from doesn‘t give us a good result of fitting.

**I would like to know how do you usually start your model planing? I just interested in the way you calculate you model: directly with all terms or by part.**

**How can I find the best diffusion factor function?**

**Very many regards in advance**

I want to employ the central composite design to optimize 4 parameters with 5 levels. I also would like to fit isotherm/Kinetic models for my batch adsorption experiments

Is it possible to plot isotherm graph from the RSM experimental design results without having to perform the traditional OFAT?

If possible kindly, explain explicitly. thank you for your answers in advance

According to below articles about kinetic modelling of ODH reactions by

**G. Che-Galicia**and et al. there are some problems need your guidance and advices:- "
**The Main article"** - https://www.sciencedirect.com/science/article/abs/pii/S1385894715008384
- https://www.sciencedirect.com/science/article/abs/pii/S1385894714004744

Q.A

- According to the nomenclature and equation 13, Kn (absorption equilibrium coefficient) should have the unit of 1 / Pa, but by referring to equation 19 Kn is unitless. why?
- According to Equation 18, the first statement in the exp function has the unit of mmol / (g.h), but the second statement is unitless, so we think A' must be outside the exp function. why?
- The quantity of Cps (solid heat capacity) and Kez (effective thermal conductivity in axial coordinate) did not reported in the main article and the references mentioned in the context of article. how can we calculate or get this property?

we emailed to authors but don't received any response !

Thank you for the time you spent reading.

Respectfully

It is very easy to specify simple kinetic models, but LHHW is not working for me. It seems that the column (radfrac) does not recognize the existence of this LHHW kinetic model, thus I am unable to set up a heterogeneous catalytic distillation column in aspen plus.

I'm starting to work with kinetic models and I want to insert some reactions into an existing model.

But I arrived at a reaction that the only data available of Vmax comes in micromol.mg-1.min-1, and COPASI only allows me to to use Vmax in mmol.L-1.s-1. Is there any way to convert the units of Vmax into the ones that COPASI requires? The only problem I'm facing is with the grams, since the moles and min units are easy to convert.

Hello everyone,

I have been working on developing a reduced kinetic mechanism for diesel-biodiesel-gasoline mixtures. I have reduced the detailed mechanisms of each individual fuel and combined them to form the final mechanism via Chemkin software.

However, throughout the combining procedure, the Chemkin software does not offer any options to specify a quota for each individual fuel before mixing, so, please kindly guide me on how can I define a specific fraction of each fuel in the final mechanism?

Thanks

I have applied the Yoon-Nelson kinetic model to the experimental data obtained for CO

_{2}adsorption on solid adsorbents. For the two materials studied, the experimental values of adsorption capacity were found to be 5.9% and 2.3% higher than those of empirical values. However, the R^{2}values were 0.998 and 0.985 respectively. Now, a journal’s reviewer is expressing disagreement with the values, pointing out that Experimental values are more than empirical values. I feel that high value of R^{2}and closeness of values (between experimental and empirical) are sufficient to show that the model fits well, as it is only empirical, not theoretical. Please comment on this.I want to study the effects of some parameters on elution phase of chromatography using lumped kinetic model (LKM) but I have writing the MATLAB code. I want to solve this using finite difference and Euler method. I have attached the equation. Can anyone please help me out?

I conducted a pesticide dissipation study and the degradation of the compound appeared to me like biphasic. So I tested three kinetic models viz. DFOP, FOMC along with the first order model or SFO in R-Studio and calculated the Chi square error value and Akaike Information Criterion or AIC value for each model to select the best fit one. Based on the calculation, the pesticide followed biphasic DFOP model as I guessed. As I communicated to a journal a comment came like: "Why you have chosen the three models?

**Briefly discuss their adaptation as well as uncertainty factor**".**I had answer for the first part but I didn't how to answer the adaptation of the kinetic models I have selected and their uncertainty. So please help.**.i do research about simultaneous photoreduction of Cr(VI) and Fe(III) by TiO2/UV. And I have problem with kinetic model for this reaction. Normally the reaction happens as:

Cr(VI) + H+ +e- --> Cr(III)

Fe(III) + H+ + e- --> Fe(II)

Can I write the overal reaction as:

Cr(VI) + Fe(III) + H+ +ne- --> Cr(III) + Fe(II)

I am trying to simulate a heterogeneous reaction between two phases in Eulerian multiphase model. I have written a UDF and it compiles and runs well. The reaction is: C+2H2--> CH4. Although my solution shows reasonable values for reactions rates, but I do not see any changes in Hydrogen concentration from the inlet gas. Can anyone where the problem is arising from?

Hello,

I'm looking for someone, who can explain me how to calculate the activation energy of the biomass pyrolysis process. I have a TGA results (mass loss in time and in temperature) with a constant heating rate. And now I don't understand how analyze these data and use the kinetics models for calculation.

Young scientist Tomasz

as mentioned in the following table, how do I arrange those kinetic models for five soils based on the highest determination coefficient( R2) and the lowest root mean square error (RMSE) please?

Residence time distribution for a tubular reactor follows semi empirical model, I want to know how can I use this RTD for predicting conversion of my system using mass balance equation for the tubular reactor( like axial dispersion model which consider reaction happening in the system as well as axial dispersion).

Based on my reading, initial adsorption rate, ho from PSO kinetic model is always been compared in research to determine which metals will be adsorbed faster or better. How does values of ho related to ionic sizes?

How can I calculate Kr and Ka for langmuir hinshelwood kinetic model? How the slope of 1/C0 vs 1/r0 plot is related to Ka and Kr?

Could the presence of ligand on a catalyst surface reduced the reactivity of its surface? If yes/no, please explain why?

Do I have to solver-add inn for its calculation?

When there is the Thiele modulus and the effectiveness factor to determine the pore resistance in catalysts, why do we need the Wagner modulus?

I am trying to develop a mechanistic model for photocatalytic degradation studies of organic compounds. Can somebody help me understand the basics

we found that the pseudo-first-order model can be described the adsorption process of methylene blue.

What does Pseudo-first-order kinetics model indicate in liquid-solid adsorption system?

How the kinetic models interpret the metal removal process?

to determined pseudo first order i follow this equation log(qe-qt)=log qe-k1t/2.303 but i found qe is lower than qt what can i do to plot log(qe-qt) versus t?

Hi,

I need to develop the kinetic model for the Ping-pong bi-bi mechanism for the lipase-catalyzed synthesis of n-butyl oleate ester according to MM model.

I have the final solution for the rate eq. and the general mechanism (files attached) but all my attempts to develop the rate eq. myself failed.

I'll be happy if you could help and show me the steps for developing the model.

thanks in advence.

I am doing a research on certain kinetic models for predicting methane production. I am having difficulty in finding the input parameters of the Richard's model. How can i find them?

I am working on color removal from wastewater using AOP and found best fit with exponential decay function 2 and 3 of Origin pro 8.5 . With some literature review some authors suggested the exponential decay function belongs to pseudo first order kinetics model and some suggested second order kinetics model.

Development of mathematical and kinetic models would start by matching a categorical example to a closely related reaction to be studied. If the selected example satisfies the characteristics of the proposed reaction having been chosen from the global option, modelling could be executed more precisely.

Theoretically, half-life according to first order kinetic model, is independent of concentration, then how the application rate of pesticide in soil is correlated with DT50?

I'm interesting in kinetic model of lignocellulose transform to reducing sugar. Please give suggestion to me.

I am doing a kinetic study on an enzymatic reaction which does not follow Michelis-Menten equations.

I am using a model to fit the experimental data, and it can fit the data for each given substrate concentration (mixed with different enzyme concentrations) very well, BUT the rate constant changes by changing the substrate concentration. In other words, the rate constant seem independent of the enzyme concentration, but somehow dependent on the substrate concentration. It should also be mentioned that in all conditions, the substrate is excessive.

I am wondering if this phenomenon is physically possible or something is wrong with the model.

Thanks.

I'm cultivating a photoautotrophic cyanobacteria (arthrospira platensis) which shows a diauxic growth curve type. What are the most used kinetic models for this kind of curve? Thanks in advance for your answers

Is there any built in equation for Lagergren's 2nd kinetic model in Origin lab? there are other models available but i am unable to find this..thanks

I am using magnetite and maghemite nanoparticles (20-80 nm) for anionic gold complex adsorption. I used Pseuso-first-order and second-order models for kinetic data fitting. in order to determine the rate-limiting step, can I use

**intra-particle diffusion model**as my adsorbent is**non-porous**. this model has been used to fit kinetic data of porous adsorbents in many of the published work. Thank you for your valuable answers.I have tried to do the pseudo-second-order kinetic plot several times using the following equation:

qt = k2*qt^2*t/(1+k2*qt*t),

but every time I am getting a flat line instead of a curve. please help me with this.

Regards.

I have been working on isoconversional methods for quite a time now. Have used all kinds of methods for kinetic analysis of my pyrolysis data: KAS, FWO, Vyazovkin, Kissinger etc. Going through literature I found, Friedman method has certain advantages over these integral methods (exclude Vyazovkin: it works quite well), but the d(a)/dT (a is normalized conversion) term has to be calculated judiciously. I have tried with forward/backward difference simply in excel ((a2-a1)/T2-T1)) and an almost similar thing in MATLAB too. But the results are not plausible enough.

I haven't tried calculating the slope at the different required points of (alpha) vs T curve, as it makes the whole analysis complex.

So what do I really do with the d(alpha)/dT term to compute kinetic parameters for my data?

An elaborate answer would be highly appreciated.

Thanks!!

Hi all,

I am working on building a kinetic model for lignocellulose decomposition in aspen. I have already defined cellulose as a solid in aspen and completed the drying part of the simulation. But when I enter lumped reaction model for cellulose decomposition in aspen using the kinetics available, it doesn't consider the solid reactions and the inlet and outlet are the same. The simulation doesn't give any errors and I am at loss on what to do. I have already tried all the solid modelling examples available in aspen. I am really hoping anyone of you can give me a clue on how to correct that error.

Thanks

I have a case in which the global equivalence ratio is about 0.5. The fuel is methane. Based on the Kinetic Modelling, the flame temperature of that equivalence ratio should be around 1800 K. However, my CFD simulation showed the flame (max) temperature to be about 2400 K. I used the Flamelet Generated Manifold for the combustion model and GRI Mech 3.0 for the Chemical Mechanism. Both the Kinetic Modelling and the CFD were on the same operating conditions, i.e. pressure ~ 16 bar and initial temperature ~ 673 K.

In the kinetics of CO2 methanation or hydrogenation of CO2, how do we determine the term equilibrium constant, Keq. In many kinetic models, rate equations we have the term Keq in the equation, how this constant is found ?

In almost all papers (eg Jacob 1976 10 lump model) discussing Fluidised Catalytic cracking of gas oils/VGO, the starting point is the continuity equation. The equation has a term labeled as Gv , superficial mass flux (kg/m2.s), which is a function of WHSV (weight feed/(weight catalyst*hr)) , catalyst bed density, length of reactor, and the void fraction (the fraction occupied by the vapour phase).

The equation looks like this:

Gv = Sv * RHOcatalyst * L/ epsilon

where

Sv : WHSV

RHOcatalyst : density of catalyst beg

L = reactor length

epsilon = void fraction.

The problem is that no explanation/derivation is provided for this equation. Any help is appreciated.

I am doing an experiment on the nutrient release from a compost over time. I have mixed the compost with soil and measure the nutrient concentrations (N, P, K) in this compost mixed soil for 0, 15, 30, 45, 60 and 75 days. Now I want to calculate the rate constant for the nutrient release and fit it to the reaction order kinetic model. How will I do that?

In syngas to olefin coversion, on the basis of catalyst and promotor..can we decide the kinetic model?

Is there any possibility of predicting that which kinetic model will be applicable by knowing the catalyst?

Kinetic and thermo data on binding kinetics of BST DNA Polymerase

Hi science hive mind!

I am running some kinetic simulations to determine the fate of a drug of interest. I am considering reactions with superoxide, hydrogen peroxide, and hydroxil radical. I am considering the Prx as the main H2O2 sink, and SOD the main O2.- target. I found an estimate that Prx can account up to 1% of cell protein, so I'm estimating the Prx molar concentrations as 1E-6. I haven't been able to find estimate for SOD molar concentrations. I am not considering multiple compartments. A range would suffice.

Thanks for your time and expertise

Dear all,

I have a sewage wastewater sample with negative zeta potential (-17.1 mV) I had treated this wastewater using a natural anionic flocculating agent and reduction in turbidity, COD, BOD, and TSS were observed. However, there is no change in the zeta potential of wastewater sample after treatment as the value for the same is -17.2 mV.

I had applied intra-particle diffusion kinetic model and it showed positive for this flocculating agent.

Kindly suggest how to describe the mechanism of action of this anionic flocculant on sewage wastewater sample when there is no change in zeta potential value.

thanks and regards

Varsha

Does anyone know how to fit nonlinear pseudo second order kinetics model using origin software? Please someone help me. I have tried a lot but failed. I want to known programming of origin according to pseudo second order kinetics model.

I have grown Yeast in synthetic medium. In two days all the substrate were consumed, However, the growth was observed until day 5 and becomes stationary after day 5. What could be the possible explanation?

Also, What will be the mathematical relation of substrate removal and delay in growth?

Im trying to fit multivariables kinetics models for cells growth. Matlab Curve Fitting app only let me introduce one independent variable.

Actually I am working on catalyst reactor fora ammonia oxidation, whose kinetic model, I want to apply on aspen plus custom model. Needs guidance or if anyone has done similar work on any sort of reactor kindly share.

The reaction is:

4NH3 + 5O2 === 4NO + 6H20

i carried out DSC-TGA for NaN3-KNO3 in nitrogen atmosphere for different heating rates. It has two peaks in DSC plot and there is an initial mass gain in TGA plot. Is it possible t o obtain activation energy (and other kinetic data) of this using models such as Kissinger, OFW, KAS, Coats Redfern etc? if so how?

In my research, I performed batch adsorption experiments of methylene blue on activated carbons. We found the following results:

- Kinetic study showed that the adsorption system followed the pseudo-second-order kinetics model;

- The Freundlich isotherm fits better the experimental data;

the adsorption of methylene blue onto optimal activated carbon was a physisorption process in nature (Thermodynamic study)

Comparing two types of insulin (fast-acting and slow-acting), can we predict which one follows presumably zero-order kinetics model?

I have calculated the activation energy from freidman's differential isoconversional method and prexponential function using compensation effect, so I have a unique value for E and A. Now I want to plot a theoretical curve of conversion (Alpha) vs Temperature using the one of the kinetic models in solid state reactions (eg. second order model or Avrami-Erofeev model).

Thank you

I would like to know if anyone knows how to plot the surface ([B] vs t vs k1/k2 ) as a numerical solution of the kinetic model of the mechanism A -> B -> C, specifically for the concentration profile of the intermediate specie [B], using any MATLAB ODE solver.

I put this question, because some researchers believe with no real grounds that this phenomenon is connected with the nonexistent surface heterogeneity of the thermally-stabilized catalyst of NH3 synthesis.

Our answer to this question is simple and unambiguous. Oxygen contaminates Fe catalyst because its heat of chemisorption at Fe is very high (about 670 kJ/mol O2, D. Brennan et al, Proc. Roy. Soc., A256, 1960, 81-105; see also https://www.researchgate.net/publication/235342853_Molar_heats_of_chemisorption_of_gases_at_metals_Review_of_experimental_results_and_technical_problems), while the heat of N2 chemisorption is about 125 kJ/mol only and because the temperature coefficient of chemisorption of two-atomic gases at metals is rather small (R.J. Madix, J. Benziger,

*Ann. Rev. Phys. Chem.*, 29 (1978) 285-306; see also https://www.researchgate.net/publication/235799473_Oscillation_theory_of_heterogeneous_catalysis_and_its_use_for_identification_of_the_reaction_scheme_and_kinetics_Catalytic_liquid-phase_benzene-ring_hydrogenation_as_an_example), while the temperature coefficient of the H2 interaction with Fe(Oads) is rather high.The Fe-catalyst surface homogeneity is hardly proved (as for other catalysts) (https://www.researchgate.net/publication/235342837_Surface_homogeneity_vs_heterogeneity_problem_for_thermally_stabilized_crystalline_bodies_and_the_nature_of_heterogeneous_catalysis; https://www.researchgate.net/publication/307920182_Energetic_homogeneity_of_thermally_stabilized_metal_and_metal-oxide_surfaces_new_oscillation_theory_of_catalysis_OTCAT_and_unification_of_catalytic_mechanisms).

It is shown that the applicability of logarithmic isotherm to some adsorption and catalytic data is explainable by the “pantophagy” of logarithmic functions over some fields of parametric variations; as for linear segments in the galvanometric charging curves obtained in some electrochemical works, there are no independent proofs that they result just from H2 chemisorption and it is not proved that the processes attributed to these segments are the equilibrium ones (https://www.researchgate.net/publication/235342837_Surface_homogeneity_vs_heterogeneity_problem_for_thermally_stabilized_crystalline_bodies_and_the_nature_of_heterogeneous_catalysis, p. 10;

Thus, the return to the opinion on a surface heterogeneity of thermally stabilized catalysts in their catalytic activity has no scientific grounds and sends us back to the erroneous views of the half-century' prescription.

Dear all,

I am in search of such an equation or model which can be used to express relative growth rate or growth kinetics of mushroom.

Your valuable suggestion will be highly appreciated.

Regards

Vinod Kumar

The Monod equation is a mathematical model for the growth of microorganisms. But the mushrooms do not follow this trend as they have a phase where spawn running is carried out. Also, the biomass increase is differed from other microbes.

The attached images shows the difference.

Please tell me can we still use Monod equation to to express specific growth rate of mushrooms and substrate utilization?

or which model will be more suitable in my case?

Thanks

I'm currently working on an adsorption experiment of several dye solutions onto chitosan hydrogel.

In literature, the two most popular kinetic models are Lagergren's pseudo-first-order model and Ho's pseudo-second-order model. By applying this model, we can find out the adsorption rate constant, k.

Based on my experimental data, I found out that changing the adsorbate concentration could change the adsorption modelling result. To be more specific, k would change, too.

However, this seems to be counter-intuitive, especially when we take into account the rate equation. Although the reaction rate could depend on the concentration, the rate constant only depends on the temperature.

I am feeling a bit confused. Does it mean I'm having a misconception about rate constant?

I´m currently working with energy storage materials. I want to know how the enthalpy value of this material is affected after several hours under a certain temperature (samples in oven). The models I´ve found so far are related to the heating rate and melting point (Kissinger equation). Since I used the same heating rate to calculate enthalpy for all my samples and the melting point doesn´t change drastically, it´s not so clear how I can use this equation or if in any case I´m using a wrong model. Is there someone who has already worked with something similar? Thank you in advance.

I have found the equation as follow:

y = 0.456x + 1.579
R² = 0.914

how can determine the n exponent to determine the mechanism of release ?

To whom it may concern

I'm trying to evaluate the reaction rate, but I don't have typical data.

I have a lot of variables. For example when the temperature is constant, "reactants molar ratio" and "contact time" are different.

One list that has less variables is "conversion-temperature" diagram.

It's my pleasure to get a help from you

best regards

In the adsorption studies during the determination of equilibrium time, usually the kinetics obey Lagergren pseudo second order model and after calculating the thermodynamic parameters and D-R parameters, physical adsorption is obtained. What could be the possible reason for this? Please attach some reference papers for help. Thank you in advance.

I was wondering if I could use BOD removal kinetics in my constructed wetland system by the process of phytoremediation.

I have already performed COD removal kinetics. I need some sorts of information like which kinetic model is best suitable for such systems?

I have these variables: Initial COD concentration (three) and retention time (days).

Please give your valuable suggestions.

Thank you.