Simple approximate analytic expression for the electrophoretic mobility of a spherical colloidal particle in a mixed solution of 1:1 and 2:1 electrolytes

Abstract

Simple approximate analytic expressions are derived for the electrophoretic mobility of a spherical colloidal particle of radius a and zeta potential ζ in a mixed solution of 1:1 and 2:1 electrolytes with common anions on the basis of the general mobility expression previously derived by Ohshima (Colloids Surf A Physicochem Eng Asp 267:50, 2005). The obtained expressions, which are applicable for spheres of any ζ and large radii such that κa ≥ ca. 30 (where κ is the Debye-Huckel parameter), consist of Smoluchowski’s equation and the correction term taking into account the relaxation effect.