The Influence of Operating Parameters on the Biodelignification of Eucalyptus globulus Kraft Pulps in a Laccase–Violuric Acid System
- 141 Downloads
The potential of a laccase mediator system on the delignification of Eucalyptus globulus kraft pulp was investigated under diverse operating conditions. A series of enzymatic treatments were performed to determine how biodelignification is influenced by pulp consistency, oxygen pressure, reaction time, dose of laccase, and dose of mediator. The mediator used was violuric acid. The results revealed that the extent of biodelignification remains practically constant between 1% and 2.5% of pulp consistency then decreases. However, its effect is less pronounced than the mediator or laccase charge. In fact, an increase in the mediator charge from 1% to 4% leads to an increase in the extent of delignification (fixed laccase charge = 20 IU/g and reaction time 120 min) from 28.4% to 52.2%. On the other hand, at a mediator charge of 4%, the increase of laccase charge from 10 to 40 IU/g has a similar impact on delignification. As for oxygen pressure, the extent of delignification increases with oxygen pressure, from 38.9% to 48.6%, when air and pure oxygen at 4 bar gauge are used. From the standpoint of reaction time, delignification is characterized by a very fast phase followed by a much slower one, leading to a plateau.
KeywordsPulp consistency Eucalyptus globulus Kraft pulp Laccase Oxygen pressure Violuric acid
This research was supported by FCT (Science and Technology Foundation-Portugal, SFRH/BD/10893/2002).
- 1.Eriksson, K.-E. L. (1997). In: Advances in Biochemical Eng. Biotechnol. Ed. Spring, Berlin, 57.Google Scholar
- 4.Viikari, L., Suurnakki, A., Buchert, J., Hejnesson, A., Carlsson, G., Strom, G., et al. (1995). In proceedings of the international symposium on wood and pulping (pp. 255–262). Finland: Helsinki.Google Scholar
- 9.Nelson, P. J., Chin, C. W. J., Viikari, L., & Tenkanen, M. (1998). Appita Journal, 51(6), 451–455.Google Scholar
- 11.Poppius-Levlin, K., Wang, W., & Ranua, M. (1998). International Pulp bleaching Conference, 1 pp. 77–86. Finland: Helsinki.Google Scholar
- 12.Allison, L., & Ragauskas, A. J. (2002). Tappi Fall technical conference and trade fair (pp. 1109–1116). San Diego, CA, United States.Google Scholar
- 15.Hsu, J. C. L., & Hsieh, J. S. (1987). Tappi Journal, 70(12), 107–111.Google Scholar
- 16.Hsu, J. C. L., & Hsieh, J. S. (1989). Tappi Pulping Conference, Tappi Proceedings (pp. 223–228).Google Scholar
- 17.Eachus, S. W. (1975). Tappi Journal, 58(9), 151–154.Google Scholar
- 18.Li, J. M., & Leod, Mc. (1993). Tappi Journal, 76(2), 159–166.Google Scholar
- 19.Singh, A. (1990). Tappi Symposium notes, Oxygen Delignification (pp. 53–59). Toronto, Canada.Google Scholar