A further simplification of the revised physical adsorption (RPA) model.

We present a further simplification of the essentially parameter-free revised physical adsorption model (K. Agashe, J.R. Regalbuto, J. Colloid Interface Sci. 185 (1997) 174) in this paper. It has been discovered that a physical adsorption model describing the uptake of various metal complexes from aqueous solutions onto oxide surfaces can most accurately simulate experimental data when the model contains only a coulombic energy term, and not a solvation energy term. The results of the simulation for cobalt/silica, chloroplatinic acid (CPA)/alumina, and tetraamonium platinate (TAP)/alumina and silica are presented here. A reasonable justification for the omission of this term is that solvation effects are negligible when adsorbing metal complexes retain one or more hydration sheaths.