Charged interfaces 205- Permittivity and viscosity are constant throughout the mobile part
of the double layer, which is described by the classical Gouy-
Chapman theory. - Only one type each of positive and negative ions are present in the
mobile part of the double layer.
Figures 7.12 and 7.13 show the result of a selection of these
computations.Figure 7.12 Eiectrophoretic mobility and zeta potential for spherical colloidal
particles in 1-1 electrolyte solutions (A+ = A_ = 70 H~' cm^2 mol"'). The curves refer
to eflkT = 1, 2, 3 and 4 (i.e. £/mV = 25.6, 51.2, 76.8 and 102.4 at 25°C) [After
P.M. Wiersema, A.L. Loeb and J.Th.G. Overbeek, /. Colloid Interface ScL, 22, 78
(1966)]Investigations of the electrophoretic behaviour of monodispersed
carboxylated polystyrene latex dispersions as a function of particle
size and electrolyte concentration by Shaw and Ottewill^191 have
confirmed, at least qualitatively, the existence of KO and relaxation
effects.