Electrophoresis of a spherical particle with an arbitrarily thick electrical double layer in a solution of macromolecules: The effect of the depletion layer

The problem of the electrophoresis of a particle in a medium with a spheric ally symmetric viscosity distribution about the center of the particle, whi ch simulates the nonuniformity of the concentration of polymer molecules ne ar the particle-surface (the depletion layer), was solved. A formula for th e electrophoresis velocity in the medium with a step-wise change in the vis cosity was derived. At the height of the step equal to zero, the expression s for the velocity transform to the Smoluchowski and Henry formulas for the thin and thick electrical double layers, respectively. Due to a decrease i n the viscosity of the depletion layer, the electrophoresis velocity is man y times higher than that calculated for the bulk viscosity of the polymer s olution.