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 been 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 the sticking dependence on coverage could be determined. The results obtained show an important modification of the sticking probabilites in the presence 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 adsorption isotherms can be obtained due to surface fractality even in the case of a lack of adsorbate/adsorbate interactions. Finally, this study supports the hypothesis that the ubiquity of Freundich and Tempkin isotherms may due to the ubiquity of fractal surfaces.