The Freundlich Adsorption Isotherm is mathematically expressed as
or
where
- m = mass of adsorbent
- p = Equilibrium pressure of adsorbate
- c = Equilibrium concentration of adsorbate in solution.
There are basically two well established types of adsorption isotherm:
- the Langmuir adsorption isotherm (see Langmuir equation)
- the Freundlich adsorption isotherm
The Langmuir adsorption isotherm describes quantitatively the build up of a layer of molecules on an adsorbent surface as a function of the concentration of the adsorbed material in the liquid in which it is in contact. In a modified form it can also describe a bi-layer deposition. The shape of the isotherm (assuming the (x) axis represents the concentration of adsorbing material in the contacting liquid) is a gradual positive curve that flattens to a constant value. It often represents an initial surface adsorption followed by a condensation effect resulting from extremely strong solute-solute interaction. In chromatography the Freundlich isotherm is not common, most adsorption processes are best described by the Langmuir isotherm.
External links
- http://www.rpi.edu/dept/chem-eng/Biotech-Environ/Adsorb/equation.htm
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Last updated on Monday November 19, 2007 at 20:03:00 PST (GMT -0800)
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