Liquid-state prebleaching of paper pulp with white rot fungi
2005
Hunsa Punnapayak(Chulalongkorn University, Bangkok (Thailand). Faculty of Science. Department of Botany. Plant Biomass Utilization Research Unit) | Mukda Kuhirun(Chulalongkorn University, Bangkok (Thailand). Faculty of Science. Department of Botany. Plant Biomass Utilization Research Unit) | Watanabe, Takashi(Kyoto University (Japan). Research Institute for Sustainable Humanosphere)
Three white not fungi including Phanerochaete chrysosporium, Ganoderma lucidum and Pleurotus ostreatus were investigated for their capabilities to prebleach eucalyptus and sugar cane bagasse paper pulp. Each fungus was incubated along with the paper pulp in a liquid-state cultivation medium containing Potato Dextrose Broth (PDB) with 0.5 percent glucose. In order to find the optimum conditions, pH was adjusted to 4.0, 5.0 or 6.0 for the prebleaching run at 30 deg C, and the temperature was finally varied to cover the wider range at 25, 35 and 40 deg C. The data suggested that prebleaching occurred during the incubation period of 14 days at 30 deg C. For the eucalyptus paper pulp, P. chrysosporium gave the brightness increase from 35.36 percent (unbleached control) to 50.76 percent at pH 5.0, while P. ostreatus gave 42.77 percent brightness at pH 5.0 and G. lucidum gave 39.97 percent brightness at pH 4.0. For sugar cane bagasse paper pulp, P. chrysosporium gave the brightness increase from 44.65 percent (unbleached control) to 54.65 percent at pH 5.0, while P. ostreatus gave 49.54 percent brightness at pH 6.0 and G. lucidum gave 51.36 percent at pH 4.0. When the incubating temperature during the prebleaching trial was raised to 40 deg C, the brightness increase was observed in the eucalyptus pulp to the values of 54.37 percent (P. chrysosporium) and 41.10 percent (P. ostreatus) while the brightness decreased to 36.4 percent in G. lucidum. The same phenomenon was observed in the prebleached sugar cane bagasse paper pulp with the brightness values of 57.78 percent (P. chrysosporium), 49.77 percent (P. ostreatus) and 46.33 percent (G. lucidum) at 40 deg C. Reduction in Kappa numbers was detected in all the prebleached paper pulp samples, in agreement with the brightness increase.
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