Theory of electrokinetic flow in fine cylindrical capillaries at high zeta-potentials

Abstract In a valuable contribution, Rice and Whitehead (16) studied theoretically electrokinetic flow in a narrow cylindrical capillary, subject only to the restriction that the zeta-potential be sufficiently low for the Debye-Huckel approximation to be acceptable (i.e., ζ ≲ 25 mV for a 1-1 electrolyte). This is a severe restriction in practice, where zeta-potentials as high as 100–200 mV are frequently encountered. The objective of this work is therefore to extend the 'Rice and Whitehead theory to higher surface potentials. The predictions obtained for streaming potential should permit an improved interpretation of experimental data taken during the course of zeta-potential determinations of fine capillaries and porous media. Of academic interest is the prediction of a maximum in the electroviscous retardation effect with respect not only to electrokinetic radius (as already reported by Rice and Whitehead) but also with respect to zeta-potential.