Effects of Zeta Potential on Dynamic Flocculation In Microparticle Systems, 1995 Papermakers Conference Proceedings

Takanori Miyanishi, Ph.D. Nippon Paper Industries, Co., Ltd. The effects of zeta potential on dynamic flocculation behavior was studied. The study was focused on microparticle retention systems in neutral papermaking. In wood containing grade when zeta potential was strongly negative, anionic PAM did not make flocs. The combination of bentonite and anionic PAM created large flocs. When the zeta potential had been adjusted near the isoelectric point by poly-DADMAC, single use of anionic PAM or bentonite formed large flocs respectively. Near the isoelectric point, chemicals primarily reacted with fibers and changed zeta potential to a larger extent than in the highly negative area. In neutral papermaking of wood free pulp, low charge and high molecular weight cationic PAM effectively made flocs. Flocs of chemical pulp were harder and were more resistant to hydrodynamic shear than mechanical pulp. Cationic starch had little effects, or in a case had unfavorable effects on flocculation. The combination of cationic PAM and bentonite worked well, when zeta potential had been previously increased to the isoelectric point. The bentonite and anionic PAM system formed large flocs even in the strongly negative zeta potential range. The suitable retention aid was selected from several cationic PAMs with various molecular weight and the charge density. KEYWORDS Zeta potential, Flocculation Formation Drainage, Retention Retention polymer, Sensor, Microparticle system