Adsorption of Tris(2,2'-bipyridine)ruthenium(II) cations at silica/aqueous solution interfaces

Abstract

The adsorption from aqueous solution of tris(2,2'-bipyridine)ruthenium(II) cations onto colloidal silica at 25ºC has been investigated. It has been shown that electrostatic attraction between the ruthenium cations and negative silica surfaces provides the main driving force for adsorption. Maximum adsorption densities are obtained at pH above 9.5 and equilibrium ruthenium concentrations above 10^-4 mol dm^-3. The maximum adsorption density appears to depend on the topography of the silica surfaces.