Polyelectrolytes are polymers that, through an ion-generating mechanism, can be linked to an electrically charged polymer molecule throughout the chain. The electric charges are due to the presence of ionizable functional groups along the polymer chain. Hence polyelectrolytes are polymer electrolytes that have both electrolyte and polymer properties. When the ionizable groups are separated, the polymer molecules are positively or negatively charged, the type of charge depends on the existing functional group.

Polymers that have positively charged ionizable functional groups (the result of all charges is ultimately positive) are called cationic polyelectrolytes, and those that are negatively charged are called anionic polyelectrolytes. Polymers whose positive and negative charges are equal and whose sum is equal to zero are called nonionics. These materials, like ordinary electrolytes, are separated depending on the pH of the water. Therefore, their properties are very similar to polymers and electrolytes. The viscosity of these materials is strongly dependent on the molecular weight and concentration of the polymer and its appearance is powdery. Other names include polyacrylamide, cationic polyelectrolyte and anionic polyelectrolyte.

Types of polyelectrolytes

  • Anionic polyelectrolyte (negatively charged)
  • Cationic polyelectrolyte (positively charged)
  • Nanionic or nonionic polyelectrolyte (no charge)

Inorganic and organic polyelectrolytes both have coagulation, flocculation and dispersion properties. The production of mineral polyelectrolytes is appropriate instead of flocculants. Organic polyelectrolytes contain high molecular weight polymers due to the deposition and solutes present. Mineral flocculants are salts of multifunctional metals such as aluminum and iron that the deposition process of these salts is completely different from organic types.

What is anionic polyelectrolyte?

Common anionic polyelectrolytes are homopolymers and copolymers of acrylic acid acrylamide salts, commonly referred to as polyacrylamides. Anionic polyelectrolyte is a water-soluble linear polymer that is synthesized under high temperature polymerization and is easily soluble in water. Anionic polyelectrolyte is almost insoluble in benzene, ether, aliphatic solvents, acetone and other organic solvents. It also has valuable properties such as flocculation, thickening, shear properties, dispersion, etc., so it is widely used in oil recycling, mineral processing, coal washing, metallurgy, chemicals, paper, textile, sugar, medicine, protection Environment, construction materials, agriculture and other industries are used.

What is a cationic polyelectrolyte?

Cationic polyelectrolytes and nanoparticles, homopolymers or copolymers with acrylamide are the three main cationic monomers that depend on a wide range of cationic polyethylenes in the presence of cationic monomer, density, charge and molecular weight. Semi-precious polyamines produced from epichlorohydrin and secondary amines such as dimethylamine are other types of low molecular weight cations that usually have very interesting applications. Acrylamide homopolymers are often included in the family of these products, and although they are uncharged, they are therefore called nonionic or nonionic.

In other words, cationic polyacrylamide, when mixed with wastewater, the active amide groups on the polymer chain adsorbent are placed on the surface of the suspended solids, creating bridges between them that begin to remove water from the newly formed structure. First the clot is small, then larger flakes are formed, which can increase the deposition rate in the clarifiers, the buoyancy rate in DAF systems, and the removal of water in the sludge thickening equipment. Cationic polyelectrolytes are widely used in domestic wastewater treatment, pulp and paper production, petrochemicals, chemicals, textiles, petroleum sands and the mining industry.

Applications of polyelectrolytes

As a coagulant in the production of drinking and industrial water in the process of clarification of raw water in various industries that have a crystallization process, such as the production of salts, edible and industrial crystals in the process of paper production and ionolite sheets coagulant of suspended solids and colloids in the concentration of liquids Organic compounds in return water Refrigeration and heating systems for the separation of solids, oils and greases and insoluble oxides in the return water treatment from the rolling section in the steel industry to remove paints, suspended solids and colloids in the petrochemical industry as coagulants in systems Treatment of industrial and sanitary effluents for simultaneous separation of light particles of fat and oil and separation of heavy particles in refining and petrochemical industries (DAF technology) Because polyelectrolytes and coagulants are high moisture absorbers, some species in the agricultural sector It is used to absorb water and increase soil water absorption coefficient.

Advantages of using polyelectrolytes

  • Requires a lower dose compared to other materials
  • Less storage time
  • It has hard, dense and compact structures
  • Low energy consumption
  • Purified drained water and reused for other purposes
  • Elimination of microorganisms
  • Reduce the volume of sludge formed
  • Larger clots formed
  • Reduce consumption costs
  • Increase the speed of settling