The dynamic double layer Part 1Theory of a mobile Stern layer

Abstract

The theory developed (C. S. Mangelsdorf and L. R. White, J. Chem. Soc., FaradayTrans., 1992, 88, 3567) to calculate the electrophoretic mobility of a solid, spherical colloidal particle subjected to an oscillating electric field is reviewed and extended. The equations governing the ion distribution, electrostatic potential and hydrodynamic flow field around the particle are modified to allow for the lateral movement of ions within the Stern layer and a time-dependent particle surface charge density. Two classes of Stern-layer adsorption isotherms are considered: (1) Adsorption of ions onto available surface area and (2) Adsorption of ions onto underlying surface charge. An equilibrium model is used for the changes in particle surface charge density arising from the flux of ions into and out of the particle surface.