Selective extraction of hemicelluloses from spruce using switchable ionic liquids

I. Anugwom*, P. Mäki-Arvela, P. Virtanen, S. Willför, R. Sjöholm, J.-P. Mikkola

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

70 Citations (Scopus)

Abstract

Switchable ionic liquids (SILs) made from alcohols, either hexanol or butanol, and CO 2 together with an amidine (1,8-diazabicyclo-[5.4.0]- undec-7-ene (DBU)) were investigated as dissolution/fractionation solvents for wood material. Both native spruce (Picea abies), and pre-extracted spruce were treated with either butanol SIL (SIL1) or hexanol SIL (SIL2) for 5 days at 55 °C under normal pressure. The SILs were formed by bubbling CO 2 through an equimolar mixture of either 1-hexanol or 1-butanol and DBU. The viscosity of the mixture increased from 7.1 mPa s to 2980 mPa s for SIL2 and 5.1 to 1600 mPa s for SIL1. Melting points of the SILs 1 and 2 were at 8 and 14 °C, respectively. After the treatment time (5 days), the undissolved fraction contained 38 wt.% less hemicelluloses compared to native spruce. There was an increase in the glucose content of the milled spruce treated with both SILs, since the milling step reduced the cellulose crystallinity of the wood and facilitated an easier SIL access into the wood. The solvents were very neutral in terms of lignin removal. Consequently, only about 2% of the lignin was removed from native wood. Moreover, a priori removal of the wood extractives did not influence the lignin removal.

Original languageEnglish
Pages (from-to)2005-2011
Number of pages7
JournalCarbohydrate Polymers
Volume87
Issue number3
DOIs
Publication statusPublished - 14 Feb 2012
MoE publication typeA1 Journal article-refereed

Keywords

  • Hemicelluloses
  • Switchable ionic liquids
  • Treatment temperature
  • Wood fractionation

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