Dynamic electrophoretic mobility of spherical colloidal particles in concentrated suspensions: approximation of nonoverlapping double layers

Abstract

An approximate expression for the dynamic electrophoretic mobility μ of spherical colloidal particles in concentrated suspensions in an oscillating electric field is derived on the basis of Kuwabara’s cell model. The analysis is constrained to low zeta potentials and nonoverlapping electrical double layers of adjacent particles. The dynamic mobility depends on the frequency ω of the applied electric field and the particle volume fraction φ as well as on the reduced particle radius κa and the zeta potential ζ. The approximation of nonoverlapping double layers is found to be valid for κa>50 (where κ is the Debye–Huckel parameter and a is the particle radius). Even for κa>10 the approximation works well for φ<0.15.