Effect of the solvent composition on the electrophoretic coefficient of polymer model colloids

An experimental investigation on electrophoresis of polystyrene beads in methanol-water and ethanol-water is described. The electrophoretic transport is considered from the point of view of Thermodynamics of Irreversible Processes. The electrophoretic phenomenological coefficient of model polymer colloids in both binary liquid mixtures has been measured. The influence of the composition of the mixture on the electrophoretic coefficient has been discussed on the basis of the variation of zeta-potential, viscosity, dielectric permittivity and density with the molar fraction of alcohol in binary mixtures, The concentration dependence of the electrophoretic coefficient is found to be non-linear in both cases studied. The zeta-potential has been shown to play a significant role in the internal structure of the electrophoretic coefficient (l(21)) for the polystyrene/water-ethanol system only.