On the Calculation of Electrokinetic Potential and Hamaker Constant of Model Colloids

Abstract

An investigation of the effect of anomalous surface conductance on ζ-potential determination of positively and negatively polystyrene microspheres is described. Also Hamaker constant of both latices is obtained by using the Spielman equations. The conversion of mobility values into ζ potentials was accomplished according to Dukhin and Semenikhin, since their theoretical treatment takes anomalous surface conductance into account. Likewise, the O'Brien and White computer program was also used to calculate ζ potentials from mobility data. The Hamaker constant obtained from log W -log C plots and DLVO theory is much lower than the theoretical value. From the comparison of Hamaker constant values obtained by Spielman equations and the theoretical method (Lifshitz theory) it is apparent that the two Hamaker constants are reasonably in agreement.