SYRINGOL AS NATURAL MEDIATOR FOR LACCASE IMPROVING THE PROPERTIES OF KRAFT PULP

摘要

In this paper, syringol was used to explore the role of natural mediator in the laccase/syringol system. The unbleached kraft pulps were treated by laccase in presence of syringol in an attempt to modify the fiber and improve paper properties. The treated kraft pulps were analyzed for kappa numbers, physical properties. The surface feature of fibers was analyzed by scanning electron microscope (SEM) and atomic force microscope (AFM). The mechanism of laccase modification of syringol was studied by using gel permeation chromatography (GPC) and FT-IR spectrum. The results showed that the kappa number of pulp treated with laccase/syringol increased by 9.63% compared with that of control sample. However, there was little difference between the kappa numbers of pulps treated with laccase and the control sample. Wet tensile strength and wet ring crush strength of handsheets treated with laccase/syringol increased by 21.16% and 19.36% respectively, compared with the control sample. The SEM and AFM results of sample treated with laccase showed that the degraded and condensed lignin deposited and encapsulated on the fiber surface, adhesion phenomenon occurred among fibers, and the surface of fibers turned rough. The images treated with laccase/syringol showed that more adhesion phenomenon occurred among fibers, and the surface of fibers became smooth. GPC results gave demonstration that the molecular weight of syringol treated by laccase increased, syingol polymerized. FT-IR spectrum determined the reaction points of syringol when treated by laccase were mainly in phonetic hydroxyl, methoxy of aromatic ring.