ELECTROKINETIC EFFECTS (ELECTROKINETICS)

"Phenomena that arise due to a charge separation caused by the relative motion of a solid and liquid phase. A portion of the Gouy-Chapman diffuse layer is sheared off as the two phases move relative to each other, resulting in a charge separation. The hydrodynamic boundary layer remains attached to the solid surface while the rest of the liquid moves separately; consequently, electrokinetic effects arise when the ""diffuse double layer"" is thicker that the ""hydrodynamic boundary layer."" The electrical potential difference between the bulk solution and the ""shear plane"" is the ""electrokinetic potential,"" often called the ""zeta potential."" Two types of effects arise: an electrical potential difference will arise between the two phases if they move relative to each other due to an external force (streaming potential and sedimentation potential) or a movement of the two phases will arise relative to each other if an electrical potential is applied parallel to the phase boundary (electroosmosis and electrophoresis). Accordingly, ""electrokinetics"" includes the following four ""electrokinetic effects:"""