LYOTROPIC EFFECT IN SURFACE-CHARGE, ELECTROKINETICS, AND COAGULATION OF A RUTILE DISPERSION

Potentiometric, electrokinetic, and coagulation experiments with a rutile dispersion in the pH region above the point of zero charge exhibit an ''inverse'' lyotropic sequence for counterions: Li+ > K+ > Cs+. The potentiometric and electrokinetic data were interpreted by a surface complexation model assuming the Stern-Gouy-Chapman structure of the interfacial layer, which yielded the values of inner layer capacitances, C, and the intrinsic equilibrium constants, K(ass)0, characterizing the specificity of each counterion. These parameters were used to explain the order of lyotropic sequences in the adsorption, coagulation, and electrokinetic phenomena.