Calculation of the electrophoretic mobility of a spherical colloid particle

A new calculation of the relation between the electrophoretic mobility and the ζ-potential of a spherical colloid particle is presented. The model consists of a rigid, electrically insulating sphere surrounded by a Gouy-Chapman double layer. The appropriate differential equations (which account for both electrophoretic retardation and relaxation effect) have been solved without approximations on an IBM 704 computer. The theoretical assumptions and the basic equations are stated. A detailed account of the solutions of the equations is published elsewhere. The present paper contains the complete results. Comparison of these results with those of Overbeek and of Booth shows that, for high ζ-potential and 0.2 < Ïa < 50, their approximations generally overestimate the relaxation effect. The application to practical cases (especially colloid particles in solutions of 1-1 electrolytes) is discussed extensively. Finally, the theoretical results are compared with experimental data published by others.