Clay flocculation improved by cationic poly(vinyl alcohol)/anionic polymer dual-component system.

The synthesis of cationically modified poly(vinyl alcohol), CPVA, by copolymerization of vinyl acetate and diallyldimethyl ammonium chloride (DADMAC), followed by alkaline hydrolysis was systematically studied. The application of the resulting polymer to the fine clay flocculation was also reported. The charge density and the structure of the resulting CPVA were characterized by polyelectrolyte titration and NMR. A photometric dispersion analyzer was used to conduct the dynamic flocculation experiments. Under fine clay experimental conditions, the CPVA alone contributed little to inducing clay flocculation. However, in conjunction with anionic polyacrylamide-based polymer with high molecular weight and low charge density, significant improvement in the flocculation of fine clay particles was achieved. The influence of factors such as pH and shear force on clay flocculation was also investigated to identify optimum application conditions for clay flocculation. The electrostatic interactions between the clay and CPVA, as well as those between the CPVA pre-treated clay and anionic polymer, were studied to explore the flocculation mechanism.