Amphophilic Cationic Polymers as Both Flocculants and Depollutants

Linear and cross-linked cationic polystyrene derivatives were prepared and tested as flocculating agents towards some silica suspensions used as model of raw water. For a ratio of substitution of the aromatic ring by an alkyl ammonium group higher than 35%, the linear polymers are water soluble and flocculate the silica suspensions according to a classical charge neutralization mechanism. The corresponding cross-linked species are very swellable gels which are also flocculants for silica but according to a different mechanism, related to heteroflocculation.