Hi Isaias,

Your problem is somewhat similar to, for example, the "ibuprofen synthesis file', which can be found on the Comsol website. I have also attached the link.

On p. 10 (at the bottom) of this pdf, you can find an example on how you can define your reactions and their rate constants in Comsol. the only thing you will need to know are the rate constants for your specific set of chemical reactions. You can find them in the literature. Especially the rate constants for the reactions involving CO2 (your reactions 1,4 and 5) are quite oftenly reported in many papers, and should be easy to find.

https://www.comsol.com/model/download/461551/models.chem.ibuprofen_synthesis.pdf

Good luck!

Niels

Thank you very much Niels, the whole idea is to couple this set of equilibrium reactions with diffusion and reactions terms and also with electromigration in COMSOL. I really appreciate your help.

Should be perfectly possible in Comsol. What’s the purpose of this modelling study. Are you working on some kind of fermentation process?

Hello again Niels, and thank you for your interest. The whole idea of this modeling effort is to calculate the pH gradients and substrate gradients inside biofilms and to couple all those process into a time-dependent study. I am studying anaerobic digestion process in biofilms. Basically consuming acetate and producing lost of protons and electrons, thats why the calculation of the pH inside the biofilms is important. But I need to do it by either considering the electroneutrality condition and applied to my equilibrium reactions or by using another approach: The proton condition.