Isotherm models

This page is dedicated to isotherm modelling and the usage of these models in MicroActive.  These updated models may be added to MicroActive version 2.01.  Please request these updates through your local Micromeritics representative.

A virial-type thermal equation

A virial-type thermal equation is an empirical model that was developed to yield an improved fit versus traditional Langmuir isotherm modelling.  It is often useful for describing heterogeneous systems.  The virial-type thermal equation approaches the Henry region at infinite dilution.

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Sips (Langmuir-Freundlich) isotherm

The Sips isotherm is a combination of the Langmuir and Freundlich isotherms and is given in the following general form:

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 Redlich-Peterson Isotherm

The Redlich-Peterson isotherm is a hybrid of the Langmuir and Freundlich isotherms.  The numerator is from the Langmuir isotherm and has the benefit of approaching the Henry region at infinite dilution.  The denominator has the hybrid Langmuir-Freundlich form.

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 Toth isotherm model

The Toth isotherm is an empirical model that was developed to yield an improved fit versus traditional Langmuir isotherm modelling.  It is often useful for describing heterogeneous systems.  The Toth isotherm model approaches the Henry region at infinite dilution.

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 Langmuir isotherm for dissociative adsorption

A Langmuir isotherm may be derived for dissociative adsorption.  This model assumes that two sites are required for sorption of the dissociated molecule.

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Freundlich isotherm

The Freundlich isotherm model is one of the first published models for use with heterogeneous surfaces.

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Temkin isotherm

The Temkin isotherm, like Freundlich is one of the earliest reported isotherm and assumes the heat of adsorption decreases linearly with increasing coverage.

Tempkin

 

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