Electrokinetic phenomena in a dilute suspension of spherical solid colloidal particles with a hydrodynamically...

A review is given on the theory of the electrokinetics in a dilute suspension of spherical solid colloidal particles with a hydrodynamically slipping surface moving in an aqueous liquid medium containing electrolytes. For a solid particle with a slip surface, the Navier boundary condition is employed instead of the usual no-slip boundary condition on the particle surface. The effect of the hydrodynamic slip is characterized by the slipping length. The limiting case of zero slipping length corresponds to a hydrophilic surface. As the hydrophobicity of the particle surface increases, the slipping length increases. The limiting case of infinitely large slipping length corresponds to a completely hydrophobic surface. General formulas and approximate expressions of the electrophoretic mobility, the electrical conductivity, the sedimentation velocity and potential, and the diffusion constant are presented. The magnitudes of the electrophoretic mobility and the sedimentation potential, in particular, are found to increase with increasing slipping length. It is also shown that a spherical solid colloidal particle with a slip surface is hydrodynamically similar to a liquid drop.