Electrophoresis of carreau-drop dispersions with a charge-regulated surface

The electrophoresis of a liquid-liquid dispersion, where the dispersed phase comprises drops of a shearing-thinning Carreau fluid with a charge-regulated surface and the dispersion medium is an aqueous electrolyte solution, is analyzed theoretically under the conditions of low surface potential, uniform weak applied electric field, and arbitrary double layer thickness. This is the first attempt for the description of the electrophoretic behavior of a dispersion containing non-Newtonian drops with a charge-regulated surface. We show that, in general, the more significant the shear-thinning nature of the drop fluid, the lower the concentration of drops, the lower the pH of bulk solution, or the higher the concentration of dissociable functional groups on drop surface, the larger the mobility. Also, the mobility of a drop may exhibit a local maximum as the thickness of the electric double layer surrounding it varies. ? 2006 American Chemical Society.