Langmuir Isotherms for a Binary Mixture

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Langmuir isotherms are generated for each component in a binary gas-phase mixture of and
. Vary the heats of adsorption of each component, the temperature, and the ratio of partial pressures with sliders. The molecules compete for adsorption sites but do not interact with each other, and this is taken into account in the form of the Langmuir isotherm. Vary the relative number of sites per molecule with a slider to account for larger molecules occupying more surface area than smaller molecules. The Langmuir isotherm for molecules
and
has the form:
Contributed by: Rachael L. Baumann (February 2014)
Additional contributions by: John L. Falconer and Nick Bongiardina
(University of Colorado, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA
Snapshots
Details
The number of molecules per site for components and
are:
,
,
where is the adsorption equilibrium constant for component
(1/bar),
is the partial pressure (bar), and
is the saturation coverage of
to
.
,
where is a pre-exponential factor (1/bar),
is the heat of adsorption (kJ/mol),
is the ideal gas constant (kJ/[mol K]), and
is temperature (K).
,
,
where is the total pressure
(bar), and
is the ratio of partial pressures.
The screencast video at [1] shows how to use this Demonstration.
Reference
[1] Langmuir Isotherms for a Binary Mixture. www.colorado.edu/learncheme/kinetics/LanmuirIsothermsBinaryMixture.html.
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