I am trying to determine Henry's Constant theoretically for Sips equation used to represent adsorption equilibrium. I could not find an easy solution. I will appreciate if somebody has a solution.
Thanks.
Shankar
I haven't anytime dealing with Sips equation, but Henry constant can be readily obtained from adsorption isotherm is you consider the isotherm only at very low coverages. The initial region of adsorption isotherm usually is linear, and the slope gives you Henry constant value.
Thanks Vladimir. As mentioned in my question, my interest is in determining 'theoretically' Henry constant for Sips isotherm equation. I can always estimate K-value by extrapolation of experimental data.
Regards.
Shankar
Hi Shankar
One of the frequently quoted disadvantages of the Sips (or Langmuir-Freundlich) isotherm equation is that it does not properly describe adsorption in the Henry's law region. So I don't think there is a solution.
See, for example, the statements in this paper:
Article Rigorous Thermodynamic Treatment of Gas Adsorption
The Tóth equation is an example of an expression that does describe adsorption correctly in the Henry's law region, so it may be better to look at another option like this; particularly if thermodynamic consistency and an accurate description of low pressure/concentration adsorption are required for your application.
Best regards,
Darren
could you find your answer? I am dealing with the same problem and do not know what to do
I prefer to calculate Henry constant either from the Langmuir model or Toth for the simpler isotherm and for complex isotherm, I prefer to use the Virial equation.
Please find supporting information of our lab work for calculation.