On the reaction mechanism of thermal yellowing of chemical pulp
2005 (English)In: Appita Annu. Conf., 2005, 517-523 p.Conference paper (Refereed)
In the present research the mechanism of colour formation in the bleached kraft pulps was studied based on the accelerated ageing experiments with industrial bleached pulps and cellulose samples doped with a number of model compounds: 2-furancarboxylic acid (FA), 5-formyl-2-furancarboxylic acid (FFA) and reductic acid (RA) in combination with Fe2+ or Fe3+ ion. The choice of the model compounds was based on the fact that they were detected in the ethanol extracts of aged industrial pulps. It was shown that the mechanism of thermal yellowing consist of several stages, including the degradation of hexenuronic acid and formation of reactive precursors, such as FFA and RA, which then take part in reactions leading to colour formation. The formation of FFA and RA is the rate-limiting stage in the discoloration of pulps. FA had basically no influence on the yellowing. The effect of Fe ions on the colour formation appears to vary with their oxidation state. The presence of Fe2+ in combination of FFA, and especially, with RA has been shown to facilitate the colour formation, whereas Fe3+ seems to suppress the discoloration caused by the FFA or RA.
Place, publisher, year, edition, pages
2005. 517-523 p.
, Appita Annual Conference, ISSN 1443-5454 ; 2
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-156495ScopusID: 2-s2.0-29344440779OAI: oai:DiVA.org:kth-156495DiVA: diva2:768103
59th Appita Annual Conference and Exhibition, incorporating the 13th ISWFPC: International Symposium on Wood, Fibre and Pulping Chemistry, 16-19 May 2005, Auckland, New Zealand
QC 201412032014-12-032014-11-282014-12-03Bibliographically approved