Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers
2014 (English)In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 34, no 4, 291-300 p.Article in journal (Refereed) Published
By varying cooking temperature, alkali charge, ionic strength, and cooking time in Kraft pulping of spruce chips, pulps ranging between kappa numbers 20-80 were obtained. The unbleached Kraft pulp fibers were subjected to mechanical peeling in order to separate the surface material from the bulk of the fibers and the carbohydrate composition and lignin content of the two fractions were analyzed. As expected, the lignin and xylan contents were higher on the fiber surface than in the fiber wall. The percentage of xylan on the fiber surface was fairly constant, independent of different pulping conditions or degree of delignification. The lignin proportion on the fiber surface gradually decreased with decreasing kappa number. At a given kappa number, pulping at a higher temperature resulted in less lignin on the fiber surface, probably because of the higher solubility of lignin at higher temperature. Cooking at lower alkali charge also resulted in lower lignin content on the fiber surface at a given kappa number. In this case, there was more time available for degradation of the surface lignin since the lower alkali charge resulted in longer cooking time needed to reach a certain kappa number.
Place, publisher, year, edition, pages
2014. Vol. 34, no 4, 291-300 p.
Kraft cooking, spruce, carbohydrate composition, fiber surface, lignin content
Chemical Process Engineering
IdentifiersURN: urn:nbn:se:kth:diva-145564DOI: 10.1080/02773813.2013.872661ISI: 000333988800004ScopusID: 2-s2.0-84896352284OAI: oai:DiVA.org:kth-145564DiVA: diva2:724068
QC 201406122014-06-122014-05-232014-06-12Bibliographically approved