INFLUENCE OF GEOMETRIC AND ENERGETIC HETEROGENEITY ON ADSORPTION-ISOTHERMS

The relationships between geometric roughness and energetic heterogene ity are discussed by considering a thermodynamically consistent model of adsorption isotherms (Keller model) which encompasses fractal scali ng and the dependence of the adsorption energies on the coverage. Expe rimental results validate this model and indicate that it call be used not only to interpolate experimental data but also to predict adsorpt ion equilibria of multicomponent mixtures. The peculiar non-Henry beha viour of the Keller model at low pressure is discussed by considering a simple model of preferential adsorption on a rough energy landscape and including the effect of surface diffusion.