The use of dielectric spectroscopy in the investigation of the effect of polymer choice on the flocculation of polystyrene particles

The flocculation of colloidal suspensions using synthetic polymeric flocculants is an important operation

in separation processes. Optimizing flocculant use requires insight into the underlying mechanisms

governing flocculation. As most existing methods for the online characterization of flocculation processes

can only be used on dilute suspensions, new methods applicable at high solid content levels are

of interest. This study used dielectric spectroscopy to investigate the mechanisms involved in the

flocculation of polystyrene particles with three different cationic polymers. We observed that the

relaxation time of the dielectric dispersion increased as particle flocculation was initiated. Reduction of

particle charge due to polymer addition was found to reduce the magnitude of the dielectric dispersion,

whereas the formation of aggregates increased it. This resulted in decreasing magnitude when charge

reduction was the primary cause of flocculation, whereas the magnitude increased when the particles

were flocculated by bridging.