Amphoteric flocculants which contains both positive and negative charge groups in the polymer chain has unique properties compared with anionic or cationic polymers with only one charge. They not only can be used as flocculants, sludge dewatering coagulants, adsorbents and metal ion chelating agents but also has the functions of neutralization, adsorption bridging, molecular winding and wrapping due to its anion and cation groups. It has good dehydration performance and metal ion removal performance, and has a wide range of pH values, so it has a wide range of applications There are two main synthetic methods:
Firstly cationic polymers are synthesized and then amphoteric polymers are obtained by partial hydrolysis. The performance test results show that the chemical oxygen demand, light transmittance and water content of the sludge filter cake of the treated sewage are better than other products. Compared with polyacrylamide, the sludge filter cake has a small water content and shows excellent flocculation performance.
Amphoteric flocculants with high viscosity, containing anionic and cationic groups are synthesized by copolymerization of acrylamide, acrylic acids and cationic monomers in the aqueous solution.