Acid soluble lignin content in kraft pulps, an artifact
2004 (English)In: 2nd International Symposium on Technologies Of Pulping, Papermaking and Biotechnology on Fiber Plants, Proceedings / [ed] Jin, YC; Xie, HF, NANJING: NANJING FORESTRY UNIV , 2004, 53-57 p.Conference paper (Refereed)
Acid-soluble lignin (ASL) has been regarded as that part of the lignin in wood or pulp that dissolves in the acidic solution during Klason lignin determination. However, the absorption at 205 nm of the filtrate for the standard ASL determination cannot be considered as originating exclusively from lignin. Moreover, the standard method has been constructed only based on lignin models from woods, plants and semichemical bisulfite pulps, while is claimed to be universally applicable. In the present work, Kraft pulps from different wood species bleached using different sequences were subjected for the ASL determination and quantifications of different furan structures in the filtrate. It has been found that during the sulfuric acid hydrolysis, 20-30% and 70-80% of the hexenuronic acid in the pulp converts into 5-formyl-2-furancarboxylic acid and 2-furancarboxylic acid respectively. Both structures absorb substantially at 205 nm and account for up to 41% of the total absorption of the filtrate. On the other hand, furfural and hydroxymethyl furfural, decomposed from hemicellulose and cellulose respectively, account for a further up to 8.7% of the total absorption. Considering also other non-lignin structures in the filtrate which absorb 205 nm, we conclude that the existence of native and modified carbohydrates makes the ASL determination meaningless for Kraft pulps.
Place, publisher, year, edition, pages
NANJING: NANJING FORESTRY UNIV , 2004. 53-57 p.
IdentifiersURN: urn:nbn:se:kth:diva-44782ISI: 000228663000011ISBN: 988-97887-7-2OAI: oai:DiVA.org:kth-44782DiVA: diva2:451249
2nd International Symposium on Technologies Of Pulping, Papermaking and Biotechnology on Fiber Plants, Proceedings
QC 201110252011-10-252011-10-252011-11-02Bibliographically approved