Flocculation of kaolin suspension with the adsorption of N,N-disubstituted hydrophobically modified polyacrylamide

The interaction between N,N-disubstituted hydrophobically modified polyacrylamide (HMPAM) and kaolin particle in aqueous suspension was investigated by determining the adsorption isotherms and the flocculation behaviors. HMPAMs with different structures varying in hydrophobic distribution degree, NH (the initial number of hydrophobic monomers per micelle during the preparation) 4.45, 2.55 and 1.79, were used in the experiment. Compared with polyacrylamide (PAM), the HMPAMs have very high-adsorbed amount that correspond to a thick adsorbed layer. These surface loads correlate positively with the effective flocculation of HMPAMs, which are attributed to the affinity and association behavior. Additionally, in the test, the HMPAMs with blocky hydrophobic distribution were better than the ones with short hydrophobic sequences. NaCl was used to detect the effect of electrolyte. As a result of the change of environment property with addition of NaCl, association behavior is promoted; consequently, adsorption and flocculation efficiency are enhanced.