Studies on the Electrophoretic Velocity of Colloidal Particles by the Moving Boundary Method. Part V. Influence of Dialysis on the Electrophoretic Velocity of Fe(OH)3 and Sb2S3 Sols in the Aspect of Thermodynamic Potential of the System and Ϛ-Potential

The effect of decreasing electrolyte concentration during dialysis on the electrophoretic velocity of lyophobic sols has been studied. The increase in electrophoretic velocity up to a certain stage of dialysis has been attributed to the inverse relation between the electrophoretic velocity and ionic strength.. The peak point observed in \(\varsigma\)-C curves is interpreted to denote the stable stage of the sol in equilibrium with a critical amount of the electrolyte. At the peak point \(du/dc\) or \(d\varsigma/dc\) is zero,which is the criterion for a maximum as well as fur the equilibrium between the charge on the colloidal particles and the counter ions in the double layer. The rise and fall of electrophoretic velocity during dialysis have been explained by the concept of the thickness of the double layer and the thermodynamic and \(\varsigma\) -potentials.