Characteristics of lignocellulosic fibers from hardwood pulp by laccase-catalyzed TEMPO oxidation

There is a challenge to find an effective and eco-friendly method to achieve the modification of fibers. The effect of laccase-TEMPO system on the properties of the bleached eucalyptus kraft pulp was investigated in this work. The results were demonstrated by the decreases in curl values and kink index. In addition, carboxyl and aldehyde groups were introduced in this reaction system. Compared with initial pulp, the contents of aldehyde and carboxyl groups of the treated pulp were increased from 42.6 μmol/g, 8.4 μmol/g to 125.4 μmol/g, 26.3 μmol/g respectively. However, the treatment had a detrimental effect on the thermal stability of pulp fibers. Moreover, the crystallinity index was slightly increased (from 82.1 % to 83.8 %) after the TEMPO-mediated oxidation, but the native crystalline structure was nearly unchanged. Furthermore, after the oxidation treatment, the relatively smooth film surface became textured, the carbon and oxygen bonds were changed, which were investigated by scanning electron microscope and X-ray photoelectron spectroscopy.