Electrophoretic mobility and primitive models:: Surface charge density effect

In the last two decades there have been a many theoretical works about the role of ionic size correlations in the electric double layer (EDL) of colloids. According to them, the effects due to the size correlations are more important for colloidal particles with large surface charge densities in solutions with high ionic concentrations. More specifically, the variation of the electrophoretic mobility (mu(e)) with respect to the surface charge density (sigma(o)) in these systems is rather different whether these correlations have been taken into account or not. On one hand, when the ionic size is included, the approximate integral equation approaches predict a maximum in the,mue-sigmao curves for elevated ionic concentrations in the case of 1:1 electrolytes and moderate concentrations of 2:2 and 2:1 electrolytes. On the other hand, for traditional theories such as the Poisson-Boltzmann (PB) approach, the size of the ions is completely neglected and mobility increases monotonically with surface charge in all cases. With regard to these discrepancies, the primary objective of this work is to show the experimental electrophoretic mobility results for latexes with variable surface charge when diverse concentrations of different electrolytes are used. These values are analyzed within the so-called hyper-netted-chain/mean-spherical approximation (HNC/MSA) and the PB approach.