Liquid Permeation of Bidisperse Colloidal Hard-Sphere Packings and the Kozeny-Carman Scaling Relation

Cyclohexane flow through binary silica sphere packings has been studied for several sphere sizes and mixture compositions. Measured permeabilities, which differ markedly from those for monodisperse packings, can be explained adequately with the Kozeny-Carman scaling relation. The particle packings are dense and statistically isotropic and it is argued that these features are essential for the Kozeny-Carman relation to apply. A quantitative test of this relation (without adjustable parameters) is in our case possible, because the size, shape, and (partial) volume fractions of the particles in the packings are known accurately. The main conclusion is that when monodisperse spheres are replaced by a binary mixture, the change in absolute permeability can be predicted from the change in specific surface area; numerical factors in the Kozeny-Carman relation remain the same.