Effects of adsorbate/adsorbate interactions and surface fractality on diffusion- and reaction-limited adsorption

The factors affecting the kinetics of adsorption on fractal surfaces have b een studied by means of a Langmuir-derived model. This model was applied to fractal model surfaces with fractal dimensions ranging from 2.35 to 2.89. The sticking probabilities of all the surface sites were estimated; thus th e sticking dependence on coverage could be determined. The results obtained show an important modification of the sticking probabilites in the presenc e of surface fractality. Furthermore, the curvature of the plot of sticking probabilities versus coverages increases with the occurrence of adsorbate/ adsorbate interactions. The present paper also shows that Tempkin-like adso rption isotherms can be obtained due to surface fractality even in the case of a lack of adsorbate/adsorbate interactions. Finally, this study support s the hypothesis that the ubiquity of Freundich and Tempkin isotherms may d ue to the ubiquity of fractal surfaces.