The influence of a bleaching sequence on the brightness stability of eucalyptus kraft pulp
2005 (English)In: Appita Annual Conference, 2005, 251-255 p.Conference paper (Refereed)
In the present research the influence of two bleaching sequences, D 0(EP)D1 (ECF-type) and Q1(OP)Q2(PO) (TCP-type), on the content of different oxidizable structures and metal ions in eucalyptus kraft pulp was studied in relation to the brightness stability of the pulp. It was shown that pulps bleached to full brightness with ECF- and TCF-type sequences contain differing amounts of oxidizable structures of carbohydrate origin, such as hexenuronic acid (HexA). These structures play a dominant role in the thermal yellowing of bleached kraft pulps and largely determine the yellowing kinetics. The most significant discoloration is observed for TCF-bleached pulps having an especially high content of HexA. The discoloration does not appear to be related to the presence of metal ions in pulps. There is a correlation between the HexA content and brightness stability of the bleached pulps. This correlation is due to reactions where HexA acts as a precursor in the formation of coloured compounds or intermediates which are then involved in the color formation. Furoic structures representing the main acid degradation products of HexA are suggested as the actual intermediates that cause yellowing by forming colored compounds.
Place, publisher, year, edition, pages
2005. 251-255 p.
, Appita Annual Conference, ISSN 14435454
Bleaching, Discoloration, Forestry
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-8866ScopusID: 2-s2.0-29344465115OAI: oai:DiVA.org:kth-8866DiVA: diva2:14334
59th Appita Annual Conference and Exhibition, incorporating the 13th ISWFPC: International Symposium on Wood, Fibre and Pulping Chemistry; Auckland, New Zealand, 16-19 May 2005
QC 201412022005-12-022005-12-022014-12-02Bibliographically approved