The most commonly used types of polyacrylamide series are cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide. So how to choose these water purification agents in the process of practical application?

The most important quality index of cationic polyacrylamide is cationic degree, because cationic polyacrylamide is made of acrylamide, cationic monomer (quaternary ammonium salt monomer) and deionized water. After being dissolved in water, it mainly carries cation, that is, positive charge. Therefore, cationic polyacrylamide is mainly used for flocculation of colloids with negative charge, and has a good effect in the process of sludge dewatering of the wastewater which with high content of organic colloid, such as sewage, construction, metallurgy, mineral processing, coal powder, oil field and so on. In contrast to cationic polyacrylamide, anionic polyacrylamide is composed of acrylamide, acrylic acid, sodium carbonate and desalted water. It mainly carries anions, i.e. negative charge. Therefore, anionic polyacrylamide is mainly used for flocculation of slurry with positive charge. It has better treatment effect for wastewater with neutral to alkaline pH, such as iron making, aluminum processing, river sand washing and electric sludge treatment, Anionic polyacrylamide is more suitable for wastewater treatment. The non-ionic polyacrylamide is composed of acrylamide and sodium acrylate, which has good effect when the suspended sewage is acidic. In conclusion, cationic polyacrylamide can be used for colloidal sludge dewatering, anionic polyacrylamide can be used for neutral to alkaline slurry wastewater, and nonionic polyacrylamide can be used for acidic suspension wastewater.