Lignin Uptake by Cellulose Fibers From Aqueous Solutions, 2002 International Pulp Bleaching Conference Proceedings
Natalia Maximova, Per Stenius
Experiments were conducted to understand the fundamentals of lignin adsorption on cellulose fibers. The effect of multivalent metal ions on the lignin adsorption was investigated. Calcium and aluminum increased the amount of lignin absorbed by inducing precipitation of lignin flocs onto the fibers. In alkaline solutions, calcium was more efficient than aluminum, while in neutral solutions aluminum had much greater effect. Apparently, charge neutralization is responsible for increase of lignin sorption. Most of the absorbed lignin bonds to the fibers reversibly, and can be easily removed by extensive washing with water. However, aluminum ions can render lignin particles cationic and make them stick to the fibers. The adsorbed lignin always has an adverse effect on the pulp and paper brightness, but not always on the sheet strength.