Significance of xylan and glucomannan in the brightness reversion of kraft pulps

Johanna Buchert, Elisabeth Bergnor, Gunnar Lindblad, Liisa Viikari, Monica Ek

Research output: Contribution to journalArticleScientificpeer-review

95 Citations (Scopus)


The brightness reversion of kraft pulps is caused by the presence of residual lignin, chlorinated extractives, or oxidized carbohydrates. The effect of hemicellulose content, i.e., xylan (I) and glucomannan (II), on the thermal stability of modern bleached kraft pulps was investigated. Different O-delignified hard- and softwood kraft pulps were bleached with different bleaching sequences contg. ClO2, H2O2, or O3. Hemicellulose-degrading enzymes, i.e., xylanase or mannanase, were used for selective removal of the resp. hemicellulose from the pulps, and the role of partially removed I and II on the brightness stability of these pulps was studied. Because of the structure of kraft I, enzymic removal of I also resulted in a decreased carboxyl group content in the pulps, whereas II removal did not affect the carboxyl group content. By decreasing the carboxyl groups in the pulps in conjunction with I removal, the thermal aging of the pulps was significantly decreased. The role of II was less significant. Thus, the uronic acids present in the pulp participate in the brightness reversion of kraft pulps.
Original languageEnglish
Pages (from-to)165-171
JournalTappi Journal
Issue number6
Publication statusPublished - 1997
MoE publication typeA1 Journal article-refereed


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