Flocculation of Kaolin Suspensions by Polyelectrolytes

The stability and flocculation of dispersions has been investigated using viscoelastic measurements and dynamic light scattering techniques. The systems studied included kaolinite, titania and polystyrene microspheres. Controlled flocculation of the system was achieved by changing the ionic strength and by adding polyelectrolytes. The viscoelastic behaviour of the suspensions with and without addition of polymer was investigated. Viscometric and oscillatory techniques proved to be powerful methods for studying the binding forces within aggregates and flocs. Also a series of aggregating suspensions was monitored by dynamic light scattering and the rate constants for the coagulation kinetics obtained. The structure factor of the flocs was calculated by computer simulation methods, assuming cluster-cluster aggregation and ballistic particle-cluster aggregation schemes. The results were interpreted in terms of the hydrodynamic radii and fractal dimensions of the flocs.