# Model development

I’m trying to develop a new isotherm which requires solving non-linear ODEs. I’m not a numerical expert but the equation seems to be similar to Bi-Langmuir or multi-state SMA, please let me know if it’s possible to solve! Thank you!

For a single component (if a multicomponent form is required, please assume no competitive effects for now):

1. pore diffusion coefficient in GRM, is it possible to make it a function of mobile phase concentration C or absorbed mab concentration q? (for instance, Dpore is a linear or exponential function of C)
2. for intra-particle porosity, is it possible to do the same and make it a linear or exponential function of q?
3. for Langmuir model, assume ligands are radially heterogenous, is it possible to make Keq as a function of radial position r. Let’s say a standard Gaussian distribution.

Thank you for putting up with me asking so many questions!

Kind regards,
Wendi Flynn Zhang.

Sorry I wasn’t clear enough for my question 1. It’s stagnant mobile phase (Cs) instead of bulk mobile phase (C). Thank you!

Dear CADET team, I’m sorry if I asked some probing questions, I mean to ask the possibilities if such a formula can be solved in theory rather than for some particular examples. All those thoughts are tentative and many parameters can be lumped into other parameters or it’s not even necessary. I hope I didn’t waste someone’s time on this. Thank you!

Hi Flynn,

Sorry for the delay and thanks for the reminder!

Yes, that’s certainly possible and since the equations don’t look very naughty, it should also be easy. Adsorption rate constant k_a and desorption rate constant k_d are the same for all stages?
There’s probably not much effort required.

That’s also possible. As of now, we have only implemented such a dependency for the surface diffusion coefficient. Since we already have this in place for surface diffusion, I expect medium effort.

Possible, but requires significant effort.

That’s certainly possible and shouldn’t require much effort. The main question here is what the interface (file format) should look like, what distributions / profiles to support etc.

That’s wonderful! I’m impressed by how powerful CADET is, I will be in touch after I finalized my thoughts on the equations!

Thank you,
Flynn.

A post was split to a new topic: Concentration-dependent Pore Diffusion