The characteristics and flocculation performance of hydrophobic association poly-(3-methacryloylamido propyl trimethyl ammonium chloride)

The cationic polymer plays a crucial role in the flocculation process for solid-liquid separation. A hydrophobic-associated cationic polymer was prepared through micellar free-radical polymerization of cationic monomer 3-methyl acrylamide propyl trimethyl ammonium chloride (MAPTAC) and hydrophobic monomer Poly (ethylene glycol) Octadecyl methacrylate (OEMA). The Poly-MAPTAC-OEMA can form network structure through intermolecular hydrophobic association in aqueous solution, which leads to the solution viscosity increase and the salt thickening property. The critical associating concentrations (CACs) of Poly-MAPTAC-OEMA are 5818-6992 mg/L in aqueous solution. For the diatomite suspensions, at the dosage above about 5 mg/L, the Poly-MAPTAC-OEMA can show higher flocculation efficiency compared with Poly-MAPTAC. Specifically, at the dosage of 8 mg/L, the enhancement rate of sedimentation rate can reach 7.27%-32.31%. Meanwhile, the hydrophobic association mainly enhances the bridging ability but has no significant effect on the improvement of the electric neutralization ability of Poly-MAPTAC-OEMA. The flocculation performance-enhanced dosage of Poly-MAPTAC-OEMA is obviously lower than the CAC of Poly-MAPTAC-OEMA; this may be because during the flocculation process, the Poly-MAPTAC-OEMA first absorb and deeply concentrate on the particle surface, and then the hydrophobic association and bridging enhancement of Poly-MAPTAC-OEMA can occur more easily on the particle surface. The flocculation mechanism hypothesis of the hydrophobic association Poly-MAPTAC.image