ON THE NATURE OF THE ENERGETIC SURFACE HETEROGENEITY IN ION ADSORPTION AT A WATER OXIDE INTERFACE - THEORETICAL-STUDIES OF SOME SPECIAL FEATURES OF ION ADSORPTION AT LOW ION CONCENTRATIONS

At low surface concentrations the log-log plots of the experimental ad sorption isotherms of ions on oxides show a transition from a linear ( Henry's) plot with a tangent equal unity to a Freundlich plot with tan gent smaller than unity. A theory has been developed reproducing that striking behavior of these adsorption isotherms. That theoretical trea tment was based on a picture of a heterogeneous solid surface, with di fferent adsorption sites-the outermost surface oxygens. Our theoretica l study indicates that the binding-to-surface energies of different su rface complexes, formed on different surface oxygens, vary in an indep endent way from one surface oxygen to another.