Isolation and Characterization of Cellulosic Pulp Fines and Their Interactions with Cationic Polyacrylamides

Abstract

Four different types of cellulosic fines were isolated from refiner mechanical and kraft pulp samples to characterize their chemical and physical properties. The pulp fines were flocculated using four different types of cationically modified polyacrylamides. The extent of flocculation was observed with multiple light scattering apparatus. The maximum adsorption of the polyelectrolytes on the pulp fines was determined by polyelectrolyte titration. It was concluded that it is the combination of the molar mass and the charge density of a polyelectrolyte, as well as the origins and characteristics of the fines which define the adsorption and flocculation behavior. None of these properties alone could fully describe these phenomena, but the molar mass of the polyelectrolyte was the predominant factor. The most important fines characteristics were the charge properties and the microstructure.

Keywords:

• Adsorption
• cellulose
• fines
• flocculation
• polyacrylamide

Acknowledgments

This research was performed as a part of the KIHA-project, which was a joint effort of three research groups from University of Oulu, VTT Technical Research Centre of Finland, and Aalto University. We thank the Finnish Funding Agency for Technology and Innovation (TEKES), M-Real Oyj, Kemira Oyj, J. M. Huber Finland Oy, and CP Kelco Oy for financing the work and supporting the materials. Dr. Joseph Campbell is gratefully acknowledged for a linguistic revision of the manuscript. We also thank the laboratory staff at our department for their skillful assistance throughout the work, and the laboratory staff at University of Oulu Institute of Electron Optics and Fibre and Particle Engineering Laboratory for the SEM imaging.

Notes

*The molar mass is an average value, given by manufacturer; The charge density was determined by polyelectrolyte titration against 2 meq/l sodium polyethylensulphonate (PesNa) solution at pH 8 and 0.1 mM NaCl; The degree of substitution is theoretical, calculated value.

Present address for S. H.: P. O. Box 44, FI-02271 Espoo, Finland.