The electrophoretic mobility of large colloidal particles

Abstract

Analytical approximation formulae linking ζ potential and electrophoretic mobility have been derived for a variety of limiting conditions. In this paper we present a simplified derivation of an equation first established by Dukhin and his collaborators for a large spherical particle with a thin double layer. Although potentially a very useful expression it has been little used to date, partly because of the complicated nature of Dukhin's derivation and partly because of the lack of a reliable method of testing its validity. The expression compares very favourably with the computer calculations of O'Brien and White, provided κa is sufficiently large.