Polyoxometalates as mediators in the laccase catalyzed delignification
authors Balakshin, MY; Evtuguin, DV; Neto, CP; Cavaco-Paulo, A
journal JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
author keywords laccase; polyoxometalate; heteropolyanion; laccase-mediator system; lignin; delignification; oxidation
keywords MODEL COMPOUNDS; OXYGEN; PULP
abstract The polyoxometalate (POM)-laccase catalytic system was applied for the first time to aerobic delignification of kraft pulps at moderate (40-60 degreesC) temperatures. Laccase was found to readily catalyze the re-oxidation of different kinds of polyoxometalates, including those, which cannot be re-oxidized by dioxygen even at high temperatures (PMo11V1, SiW11V1. etc.). This allows a sequence of catalytic redox cycles similar to that in the laccase-mediator system (LMS) where electrons are transferred from the substrate (lignin) via POM and laccase to oxygen. Results obtained showed that the POM-laccase system could decrease kappa number of eucalypt kraft pulp from 13.7 to 8.5 though the reaction rate is relatively slow. Among different POM used, SiW11V showed the best results. The effect of the process variables on the delignification was studied. The best results in delignification of eucalypt pulp were obtained at 60 degreesC, oxygen pressure of 5 bar, pH 6.3, SiW11V concentration of 4.2 mM and laccase concentration of 0.65 U/ml. The reaction temperature appears to be one of the crucial factors in the achievement of a delignification rate acceptable for practical application. (C) 2001 Elsevier Science B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 1381-1177
year published 2001
volume 16
issue 03-abr
beginning page 131
ending page 140
digital object identifier (doi) 10.1016/S1381-1177(01)00054-6
web of science category Biochemistry & Molecular Biology; Chemistry, Physical
subject category Biochemistry & Molecular Biology; Chemistry
unique article identifier WOS:000172747200002
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