O. García, S. Camarero, J. F. Colom, Á. T. Martínez, M. J. Martínez, R. Monje, T. Vidal
Optimization of a Laccase-Mediator Stage for TCF Bleaching of Flax Pulp
Summary
Flax pulp obtained by anthraquinone-soda pulping, resulting in a kappa number of 11.1, a viscosity
of 950 ml/g and 36.7% ISO brightness, was bleached in a totally chlorine-free sequence using the
enzyme laccase from the fungus Pycnoporus cinnabarinus and 1-hydroxybenzotriazole (HBT) as
redox mediator (stage L), followed by a hydrogen peroxide stage (P). The laccase treatment was
optimized using a three-variable sequential statistical plan over the following ranges: 1–20 U/g
o.d.p. (oven-dried pulp) laccase dose, 0.5–7.5% o.d.p. HBT dose and 1–24 h reaction time. The influence
of these variables on several pulp properties after the P stage of the LP sequence was examined.
The models defined from the results obtained predicted variations in ISO brightness, viscosity
and kappa number of 57.6–74.8%,590–955 ml/g and 0–6.2, respectively. The variables most
strongly influencing these pulp properties were found to be the reaction time and the enzyme
dose. A compromise was adopted as regards the operating conditions in order to ensure optimum
results. The study was completed by conducting a biobleaching assay in a pressurized reactor
(590 kPa) to assess the effect of oxygen pressure. The high pressure level resulted in improved pulp
properties by the laccase-mediator system.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 57, 08/2003
Pages: 513 - 519
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