Nowadays, the application of laccases to the bleaching processes is widely studied because not only are they able to degrade lignin with high selectivity, but also to reduce the pollution levels in the bleaching effluents by means of increasing the efficiency during subsequent bleaching steps. To ensure optimal conditions during the enzymatic bleaching of the laccase produced by Trametes sp I-62, the enzyme stability at different pH and temperature values was studied. The enzymatic bleaching was then applied on Eucalyptus globulus kraft pulp using a laccase-mediator system. Then, an alkaline extraction and a hydrogen peroxide steps were carried out to evaluate the efficiency of enzymatic bleaching. Finally, a comparison using a laccase from Pycnoporus sanguineus is shown. Although both bleaching processes showed a reduction in the consumption of hydrogen peroxide, laccase from Trametes sp I-62 was more efficient in brightness increase than in delignification compared to laccase from Pycnoporus sanguineus.

Efficiency of laccases produced by Trametes sp I-62 and Pycnoporus sanguineus applied to Kraft pulps bleaching

241st National Meeting (2011)

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