Towards a new concept of lignin condensation in kraft pulping. Initial results
2004 (English)In: Comptes rendus. Biologies, ISSN 1631-0691, E-ISSN 1768-3238, Vol. 327, no 9-10, 817-826 p.Article in journal (Refereed) Published
In kraft pulping, a comparatively large amount of lignin remains in the fibres after the cook. Based on various analytical techniques for lignin, such as thioacidolysis, GPC and NMR, it is suggested that lignin condensation reactions take place during the cook. The reaction seems, however, not to involve ionic intermediates as has been suggested previously but rather a one-electron mechanism with elemental sulphur as the initiator. Support for such a reaction has been found through kraft cooks in the presence of an added phenol, 2,6-xylenol, as well as through NMR analysis of kraft lignin. It was found that the added phenol is incorporated in the pulp lignin with linkages indicative of radical coupling. Furthermore, kraft lignin was found to contain substantial amounts of chemically linked fatty acids. By complementary analyses of sulphur and polysulphide in an industrial black liquor, the presence of these compounds throughout a kraft cook was demonstrated.
Place, publisher, year, edition, pages
2004. Vol. 327, no 9-10, 817-826 p.
Condensation, Electron transfer reactions, Fatty acids, GPC, Kraft pulping, NMR analysis, Phenols, Thioacidolysis
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-5372DOI: 10.1016/j.crvi.2004.03.011ISI: 000225355200007ScopusID: 2-s2.0-9244265580OAI: oai:DiVA.org:kth-5372DiVA: diva2:9721
QC 201010042006-02-142006-02-142011-09-23Bibliographically approved