Adsorption of surfactant on colloidal particles

For a smooth spherical or cubic particle, adsorption should scale with the square of the particle size. Work in our lab with three different particle compositions that have been reduced in size via ball milling indicates that such scaling is not followed where surfactant adsorption is measured, adsorption scales linearly with particle size. The particles show no obvious anisotropy; so macroscopic particle shape is not an explanation as could be the case for cylindrical particles for example. An explanation for this scaling behavior will be presented, along with a comparison of the results from nitrogen adsorption which reveals something beyond surfactant adsorption.