Electrophoretic Mobility of a Concentrated Suspension of Spherical Particles.
The electrophoretic behavior of concentrated spherical colloidal particles is analyzed theoretically for all levels of scaled surface potential &phi;a, taking the effect of double-layer polarization (DLP) into account. The result of numerical simulation reveals that for a very small kappaa (<0.01), kappa and a being, respectively, the reciprocal Debye length and the particle radius, or a very large kappaa (>100), using a linearized Poisson-Boltzmann equation (PBE) and neglecting the effect of DLP is reasonable; for an intermediate kappaa, appreciable deviation may result. The deviation is negative if kappaa is small, and positive if kappaa is large. The mobility against kappaa curve may have a local minimum and a local maximum. If &phi;a is low, the mobility increases with the porosity of the system under consideration, and for a fixed porosity, the mobility increases with kappaa. If &phi;a is high and kappaa is small, the effect of &phi;a (i.e., solving a nonlinear PBE) on the mobility of a particle is more significant than that of double-layer polarization, and the reverse is true if kappaa is large. For an intermediate kappaa, the effect of DLP is more significant than that of &phi;a when the porosity is high, and the reverse is true if it is low. Copyright 1999 Academic Press.