An Investigation of the Theoretical Derivation of Freundlich Isotherm

A model was set up for the adsorption system in which the lateral interaction between the adsorbed molecules was considered. According to this model, Freundlich isotherm, in the form of θ=KP^1/n, was derived by means of the ensemble theory in statistical mechanics. This theoretically derived expression established the relationship between empirical constants K, n and the microscopic properties of the adsorbed molecules. The validity or this theoretically derived expression was demonstrated by examining the dependence of K and n with temperature and the variation of the differential heat of adsorption with coverage. The possibility of using this theoretically derived expression to evaluate, in principle, the microscopic properties of the adsorbed molecules on the solid surface from the adsorption data was also presented.