FLOCCULATION OF MONTMORILLONITE DISPERSIONS BASED ON SURFACTANT-POLYMER INTERACTIONS

A two-step flocculation process is described in which a polycation (po lydiallyldimethylammonium chloride) is adsorbed on to negatively charg ed montmorillonite particles, followed by the addition of an anionic s urfactant [sodium dodecyl sulfate (SDS)]. At a 1:1 molar ratio, optima l flocculation is obtained owing to the formation of an insoluble surf actant-polymer complex in the presence of the particles. The precipita tion of the insoluble complex is also dependent on the SDS and polymer concentrations, and occurs at a 1.1 SDS:monomer molar ratio. From ads orption isotherms of the polymer-particle and surfactant-polymer syste ms, the adsorption energy was calculated and subsequently a flocculati on mechanism is suggested.