resumo
Oxidation of the manganese-substituted polyoxometalate [SiW(11)Mn(II)(H(2)O)O(39)](6-) (SiW(11)Mn(II)) to [SiW(11)Mn(II)(H(2)O)O(39)](5-) (SiW(11)Mn(II)), one of the most selective polyoxometalates for the kraft pulp delignification, by versatile peroxidase (VP) was studied. First, SiW(11)Mn(II) was demonstrated to be quickly oxidized by VP at room temperature in the presence of H(2)O(2) (K(m)= 6.4 +/- 0.7 mM and k(car) = 47 +/- 2 s(-1)). Second, the filtrate from eucalypt pulp delignification containing reduced polyoxometalate was treated with VP/H(2)O(2), and 95-100% reoxidation was attained. In this way, it was possible to reuse the liquor from a first SSiW(11)Mn(III) stage for further delignification, in a sequence constituted by two polyoxometalate stages, and a short intermediate step consisting of the addition of VP/H(2)O(2) to the filtrate for SiW(11)Mn(II) reoxidation. When the first ClO(2) stage of a conventional bleaching sequence was substituted by the two-stage delignification with polyoxometalate (assisted by VP) a 50% saving in ClO(2) was obtained for similar mechanical strength of the final pulp. (C) 2010 Elsevier Ltd. All rights reserved.
palavras-chave
SITE-DIRECTED MUTAGENESIS; OXYGEN DELIGNIFICATION; PLEUROTUS-ERYNGII; OXIDATION; ENZYMES; SYSTEM; ECF
categoria
Agriculture; Biotechnology & Applied Microbiology; Energy & Fuels
autores
Marques, G; Gamelas, JAF; Ruiz-Duenas, FJ; del Rio, JC; Evtuguin, DV; Martinez, AT; Gutierrez, A
nossos autores
Dmitry Evtyugin
Professor Associado com Agregação
José António Ferreira Gamelas
Bolseiro de pós-Doutoramentoagradecimentos
This study has been supported by the EU project BIORENEW (NMP2-CT-2006-026456) and the Spanish projects AGL2008-00709 and BIO2008-01533. We thank ENCE (Pontevedra, Spain) for pulp samples. G. M. and F. J. R.-D. thank the Spanish MICINN for a FPI fellowship and a Ramon y Cajal contract, respectively.