Interactions between smectites and polyelectrolytes

Abstract

Interactions between smectite and polyelectrolyte play an essential role in exclusive adsorption, flocculation, and thixotropic properties of aqueous smectite/polyelectrolyte system. The materials are widely used in many industries such as drilling fluids, pharmaceuticals, paints and dyes, ceramics, papermaking and water treatment. This review focuses on the interaction between different types of polyelectrolytes and smectite, and their applications in flocculation and industrial wastewaters. The effect of several parameters related to polyelectrolyte such as charge density, charge type and molecular weight, as well as to smectite such as type, particle size, composition, pH and concentration in the aqueous system, were examined. The interactive forces between smectite and polyelectrolyte including hydrophobic interaction, ion binding, hydrogen bonding, van der Waals forces and electrostatic were thoroughly discussed. The interactive forces between smectite and cationic polyelectrolyte, anionic polyelectrolyte and amphoteric polyelectrolyte influence the flocculation of colloidal smectite-polyelectrolyte dispersions such as settling and floc dispersion. However, the interaction between smectites and polyelectrolytes and their subsequent behaviors in adsorption, flocculation, and thixotropy along with inherent mechanisms have not yet fully understood. Future in-depth work on interactions between smectites and polyelectrolytes has great implications for developing functional materials and expanding applications of other polyelectrolyte/ smectite mineral system.