Clay retention induced by poly (ethylene oxide) with various cofactors

The retention aid poly(ethylene oxide) (PEO) needs a cofactor to work effec tively. Although the cofactor phenol formaldehyde resin (PFR) has been stud ied in several investigations, little has been published about the effectiv eness of other possible cofactors. In the present work, two novel cofactors ,an anionic acryl-sulfonate resin (ZFN) and an anionic phenylsulfonate resi n (DP5), performed better than PFR in inducing flocculation of fine clay pa rticles (average size 0.6 mu m). Similar results were also observed for cla y flocculation in the presence of recycled newsprint fibres. Investigations of the effects of polymer dosage and shear rates on flocculation and flee sizes revealed that the system PEO/ZFN forms larger flocs than other system s, but that the clay flocs tend to decay in size: these observations sugges t that the flocs might be formed by a transitory PEO/cofactor complex which breaks up when exposed to high shear stress.