Characterisation of residual lignins in pulps delignified by laccase/N-hydroxyacetanilide

Kristiina Poppius-Levlin, Tarja Tamminen, Anna Kalliola, T. Ohra-aho

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    11 Citations (Scopus)

    Abstract

    A pine kraft pulp and a two-stage oxygen-delignified pine kraft pulp were delignified with laccase in the presence of N-hydroxyacetanilide (NHA). Laccase/NHA was selective in its reactions with lignin: 30% delignification was obtained under the moderate reaction conditions employed, while the carbohydrates remained unattacked. Laccase/NHA did not react with neutral pulp carbohydrates or with uronic acids. Beside delignification, laccase/NHA caused chemical modification of fiber lignin, lowering the content of free phenolic hydroxyl groups and thus verifying their importance in delignification. Oxidation of the residual lignins was clearly observed as a decrease in methoxyl groups and a simultaneous increase in conjugated carbonyl groups, carboxyl and/or ester groups. Only 50-60% of the pulp residual lignin retained its aromatic structure. Pyrolysis-GC/MS gave important information, not only of the chemical structure of residual lignins, but also of the behavior of the mediator during delignification. Residuals of aniline and acetanilide, i.e. degradation products of NHA, were found among thepyrolysis products of residual lignins. However, only trace amounts of NHA-derived nitrogen-containing products were present in the lignins.
    Original languageEnglish
    Title of host publicationOxidative Delignification Chemistry
    Subtitle of host publicationFundamentals and Catalysis
    EditorsD.C. Argyropoulos
    PublisherAmerican Chemical Society ACS
    Chapter22
    Pages358-372
    ISBN (Electronic)978-0-8412-1853-6
    ISBN (Print)978-0-8412-3738-4
    DOIs
    Publication statusPublished - 2001
    MoE publication typeA4 Article in a conference publication
    Event219th American Chemical Society ACS National Meeting - San Francisco, United States
    Duration: 26 Mar 200031 Mar 2000

    Publication series

    SeriesACS Symposium Series
    Volume785
    ISSN0097-6156

    Conference

    Conference219th American Chemical Society ACS National Meeting
    CountryUnited States
    CitySan Francisco
    Period26/03/0031/03/00

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