On the isolation and structure of softwood residual lignins
2002 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 17, no 2, 193-198 p.Article in journal (Refereed) Published
Different softwood residual lignins were isolated by acid hydrolysis of kraft and soda Pulps. Complete isolation of lignin Could not be achieved in one hydrolysis step. The yield of lignin varied between 35 and 55%. A more acidic, second hydrolysis step was therefore necessary to isolate almost all the lignin remaining in the Pulp residue, giving a total lipin yield of 91%. Alkaline extraction of the pulp was almost as efficient as acid hydrolysis in isolating residual lignins. However, alkaline extraction gave less pure lignin fractions and there was a clear indication of the existence of lignin-carbohydrate bonds. Pine wood meal was acid-hydrolyzed in the same way as the pulps. After two-stage acid hydrolysis, the combined lignin yield was only 45% of the Klason lignin content, which means that native lignin is more difficult to isolate front wood than residual lignin front a chemical pulp. It is Concluded that the difficulty encountered in isolating residual lignin by acid hydrolysis is a problem of limited accessibility due to a complex carbohydrate network surrounding the lignin.
Place, publisher, year, edition, pages
2002. Vol. 17, no 2, 193-198 p.
acid hydrolysis, alkaline extraction, dissolved linin, C-13-HSQC NMR, LCC, MWL, residual lignin, pulps
IdentifiersURN: urn:nbn:se:kth:diva-21635ISI: 000176358700015OAI: oai:DiVA.org:kth-21635DiVA: diva2:340333
QC 201005252010-08-102010-08-10Bibliographically approved