Title: A Comparison of Streaming and Microelectrophoresis Methods for Obtaining the ζ Potential of Granular Porous Media Surfaces
Abstract: The electrokinetic behavior of granular quartz sand in aqueous solution is investigated by both microelectrophoresis and streaming potential methods. ζ potentials of surfaces composed of granular quartz obtained via streaming potential methods are compared to electrophoretic mobility ζ potential values of colloid-sized quartz fragments. The ζ values generated by these alternate methods are in close agreement over a wide pH range and electrolyte concentrations spanning several orders of magnitude. Streaming measurements performed on chemically heterogeneous mixtures of physically homogeneous sand are shown to obey a simple mixing model based on the surface area-weighted average of the streaming potentials associated with the individual end members. These experimental results support the applicability of the streaming potential method as a means of determining the ζ potential of granular porous media surfaces.