Freundlich Adsorption Isotherm
An empirical relation describing adsorption on heterogeneous surfaces with a distribution of site energies.
Formula / equation
x/m = k p^(1/n)
Unit
mol/g
In depth
With n greater than one, the equation gives a curve that fits intermediate-pressure data well but has no saturation limit, so it fails at very high pressures. Plotting the logarithm of adsorbed amount against the logarithm of pressure yields a straight line from which k and n are obtained.
Examples in the real world
Acetic acid adsorbing onto activated charcoal from aqueous solution.