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.

Residue-Free and Recyclable Starch-Based Flocculants for Dye Wastewater Flocculation

“…In this phase, the positive charges on the LMTS are completely exposed, leading to the molecular chain extension. Once LMTS neutralizes the anions on the dye molecules, it is destabilized owing to van der Waals forces with the formation of small aggregates . These micro aggregates display negatively charged regions and positively charged cationic chain segments on their surfaces.…”

“…Once LMTS neutralizes the anions on the dye molecules, it is destabilized owing to van der Waals forces with the formation of small aggregates. 47 These micro aggregates display negatively charged regions and positively charged cationic chain segments on their surfaces. The lengthy cationic chain segments on LMTS serve as bridges, linking numerous micro aggregates and giving rise to larger flocs (Figure 5c).…”

Organobentonite Binder for Binding Sand Grains in Foundry Moulding Sands

“…PAA has reactive functional groups in the form of carboxyl groups, which provide the macromolecule with a high negative charge density upon dissociation. This makes them, together with poly(sodium acrylate), one of the most commonly used water-soluble anionic polyelectrolytes, e.g., in the production of hydrogels, so-called superabsorbents, and ion exchange resins, or as dispersing and binding agents [ 24 , 25 , 26 ]. Therefore, possessing properties valuable from the point of view of the requirements for casting binders in synthetic moulding sand technology, the selected polymers represent a promising material for the modification of the structure of the main component of bentonite [ 27 ].…”

Flocculation Performance of Industrial Sugarcane Juice by Acrylamide-Based Anionic Flocculant

“…In cane sugar juice, binding of copolymer microflocs most likely proceeds primarily by the attraction of the negatively charged acrylate groups to dipositive ionic bridges (e.g., Ca 2+ ), which are adsorbed to negative charges on the microfloc particles. However, it is still possible that they may proceed by two other mechanisms i.e., attraction of the negatively charged acrylate groups to positive charges on the surface of the microfloc particles and hydrogen or dipolar bonding between the acrylamide groups and the microfloc particles [21][22][23][24][25].…”