The Freundlich isotherm model is one of the first published models for use with heterogeneous surfaces.
A value of 1/n less than 1.0 implies chemisorption and values greater than 1.0 may be indicative of cooperative adsorption. The Freundlich isotherm is part of the standard Micromeritics physical adsorption isotherm modelling package and has also been added to MicroActive.
Freundlich HMF, Uber die adsorption in losungen, Z Phys Chem. 1906;57(A):385–470