A New Approach to the Theory for Adsorption Isotherms on Heterogeneous Surfaces

Simulations of the adsorption of nitrogen on several model heterogeneous surfaces (Cascarini de Torre and Bottani, 1997) are analyzed using an alternative description in which the surface is treated as a collection of supersites, each of which can hold 5–6 molecules in the complete monolayer. The local isotherm that is used to describe the sub-monolayer adsorption on a supersite is here taken to be the truncated virial isotherm. This theory fits well to the simulated data. The advantages and disadvantages of this approach are discussed and it is concluded that the supersite concept is a promising approach to the description of a adsorption on realistic models of heterogeneous surfaces.