Interaction Modelling of PCC Flocculation Induced by Cationic Polymer for Water Clarification

Abstract

The precipitated calcium carbonate (PCC) has been extensively used as additives in various industrial applications, particularly as fillers for papermaking. Due to the limited retention being achieved in application, it is necessary to clarify the PCC suspension after the application. Cationic polymers are often used as flocculants to induce the aggregation of PCC particles and facilitate the removal of PCC in water clarification. In this work, we focused on identifying the optimum dosage of the polymer and understanding the flocculation mechanism via the characterization of the zeta potential of the PCC suspension. Moreover, the free energy of interaction between PCC particles covered by polymer was investigated using a surface energy modelling that simulated the interaction under various polymer coverages. The modelling results indicated that the electrostatic free energy increased as the surface coverage increased from 33.7 to 81.8 %. The model also enables to predict the total free energy and the electrostatic energy as a function of the separation distance in spite of the lack of complete agreement with the experimental observation.

Keywords: Cationic polymer, flocculation, free energy, modelling, PCC, Zeta-potential