Effect of cooking and bleaching on the structure of xylan in conventional pine kraft pulp

Johanna Buchert, Anita Teleman, Vesa Harjunpää, Maija Tenkanen, Liisa Viikari, Tapani Vuorinen

Research output: Contribution to journalArticleScientificpeer-review

29 Citations (Scopus)

Abstract

Pine chips were cooked with a conventional kraft process, and the structure of the surface xylan as a function of the cooking time was analyzed by enzymatic peeling and 1HNMR spectroscopy. A brownstock pulp with kappa no. 25.9 was
also bleached to about 80% ISO brightness with bleaching sequences OZEP, OPZEP, OPPP, and ODEDED. The structure of the kraft pulp xylan was different from the native wood xylan. During kraft pulping, the 4-O-methylglucuronic
acid (MeGlcA) sidegroups were converted to 4-deoxyhex-4-enuronic acid (HexA) groups almost completely, and as a consequence, only about 12% of the carboxylic groups of the accessible xylan were 4-O-methylglucuronic acid groups. During bleaching with ozone or chlorine dioxide, the hexenuronic acid sidegroups of pulp xylan were, however, degraded, whereas the MeGlcA and arabinose sidegroups were relatively stable toward the bleaching chemicals. Thus, both cooking and bleaching affect the carboxylic acid profile and content in kraft pulps.
Original languageEnglish
Pages (from-to)125-130
JournalTappi Journal
Volume78
Issue number11
Publication statusPublished - 1995
MoE publication typeA1 Journal article-refereed

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