Wet strength improvement of unbleached kraft pulp through laccase catalyzed oxidation

• Published in: Enzyme and microbial technology Vol. 28; no. 9; pp. 760 - 765
• Main Authors: Lund, Martin, Felby, Claus
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 07.06.2001; Elsevier Science
• Subjects: Biological and medical sciences; Biotechnology; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Kraft pulp; Laccase; Lignin; Mediator; Other applications; Oxidation; Wet strength; Lignin; Oxidation; Mediator; Kraft pulp; Laccase; Wet strength; Enzymatic treatment; Heat treatment; Enzyme; Transferases; Paper pulp; Wet resistance; Tensile strength; Paper industry; Methyltransferases; Sulfite pulp; 10-Hydroxydihydrosanguinarine 10-O-methyltransferase; Oxidoreductases
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/S0141-0229(01)00339-8

Previous investigations have shown that laccase catalyzed oxidation of lignin containing wood fibers can enhance the strength of medium density fiberboards. In the present work it was investigated if laccase treatment had any impact on the tensile strength of a high yield unbleached kraft pulp. Treatment with laccase alone had only a very little effect on the wet strength of the pulp, whereas addition of lignin rich extractives increased the wet strength after the enzyme treatment significantly. A mediated oxidation gave a similar improvement of the wet tensile strength although no lignin was added to the fiber suspension. Furthermore, it was found that a heat treatment combined with a mediated oxidation gave a higher improvement in wet tensile strength than could be accounted for by the individual treatments. No change in dry tensile strength from the laccase treatment was observed. It is suggested that the observed improvement in wet tensile strength is related to polymerization of lignin on fibers in the hand sheet and/or coupling of phenoxy radicals on lignin associated to adjacent fibers. For the different mediators studied, a correlation was found between oxygen consumption upon mediated oxidation and generation of wet strength in the pulp.