Biobleaching and Fiber Properties Improvements by Laccase-Mediator System

Masson pine Kraft pulp was treated with laccase from a white rot fungus Flammulina Velutipes with laccase-mediator system (LMS). Different TCF bleaching sequences in combination with LMS treatment were evaluated by the properties of final Pulp and physical properties (tensile, tear, and burst) of the handsheets. The results showed that treatment of laccase enhanced not only optical properties but also physical strength of final pulps. In addition, crystallinity and carboxyl acid group content of the Masson pine pulp were tested by X-ray Diffraction (XRD) and Headspace Gas Chromatography (HS-GC). It was found that enzymatic treatment affected the crystallinity of cellulose fibers. The maximum crystallinity of the cellulose was shown in OLQP bleached pulps, which has best physical properties among the fully bleached pulps. Also a prominent increase in the content of carboxyl acid group was attained after LMS treatment, which gives a better understanding of the improvement of physical strength of the biobleached pulps.