Adsorption
Use this node to model adsorption of the fluid phase species onto the porous media surface. It is available as a subnode to the Porous Media Transport Properties and the Partially Saturated Porous Media nodes.
This feature is only available in a limited set of add-on products. See https://www.comsol.com/products/specifications/ for more details on availability.
Matrix Properties
Use the Porous material list to define a material specifying the matrix properties on the current selection. By default the Domain material is used.
The density of the porous media is needed when modeling adsorption to the surface of the porous matrix. By default Density ρ is defined from the domain material.
Adsorption
Select a Sorption type — Langmuir (the default), Freundlich, Toth, BET,or User defined to specify how to compute cP, the amount of species sorbed to the solid phase (moles per unit dry weight of the solid):
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For Langmuir:
Enter a Langmuir constant kL,c (SI unit: m3/mol) and an Adsorption maximum cp,max,c (SI unit: mol/kg).
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For Freundlich:
Enter a Freundlich constant kF,c (SI unit: mol/kg), a Freundlich exponent NF,c (dimensionless), and a Reference concentration cref,c (SI unit: mol/m3).
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For Toth:
and
Enter a Toth constant bT,c (SI unit: m3/mol), a Toth exponent NT,c (dimensionless), and an Adsorption maximum cp,max,c (SI unit: mol/kg).
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For BET (Brunauer-Emmett-Teller):
and
Enter a BET constant KB,c (dimensionless), a Monolayer adsorption capacity c0,c (SI unit: mol/kg), and an Saturation concentration cS,c (SI unit: mol/m3).
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For User defined:
Enter an Adsorption isotherm cP,c (SI unit: mol/kg).
For more information, see Adsorption in the theory section.
Further Reading
See the theory chapter in the section Mass Balance Equation for Transport of Diluted Species in Porous Media.