Enhancement of TCF and ECF bleaching processes by urea and enzymatic pretreatments Optimization of a laccase-mediator pretreatment
A TCF bleaching sequence consisting of a urea pretreatment stage (U), laccase-mediator system stage (L), alkaline extraction stage (E), and hydrogen peroxide bleaching stage (P) was used to study the effect of five independent variables on the dependent variables pulp properties, hydrogen peroxide consumption, and residual enzyme activity. Results showed that the most influential variable was L stage pulp consistency, followed by mediator and laccase dosages. On the other hand, oxygen pressure did not have a significant effect. The optimal UL partial sequence significantly enhanced the EP bleaching sequence 49.8% vs. 33.4% delignification, up to 65.6% ISO vs. 56.3% ISO bleached brightness, and 50.3% vs. 89.9% peroxide consumption in the P stage. The ULE partial sequence also improved an ECF bleaching sequence (ULED<inf>0</inf>E<inf>1</inf>D<inf>1</inf>) 0.6 vs. 1.0 final kappa number; 82.7% ISO vs. 76.0% ISO brightness; and 54.1 N·m·g-1 vs. 51.9 N·m·g-1 and 3.3 KPa·m2·g-1 vs. 2.7 KPa·m2·g-1, tensile and burst indexes, respectively, when compared to the control D<inf>0</inf>E<inf>1</inf>D<inf>1</inf> sequence.
| Main Authors: | , , , , |
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| Format: | journal article biblioteca |
| Language: | English |
| Published: |
North Carolina State University
2015
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| Subjects: | Pycnoporus sanguineus, Urea, Bleaching variables, Optimization, Eucalyptus globulus, Kraft pulp, |
| Online Access: | http://hdl.handle.net/20.500.12792/1593 http://hdl.handle.net/10261/293594 |
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