Fractionation of lignocellulosic materials using ionic liquids: Part 2. Effect of particle size on the mechanisms of fractionation

Research output: Contribution to journalArticle


  • Timo Leskinen
  • Alistair W T King
  • Ilkka Kilpeläinen
  • Dimitris S. Argyropoulos

Research units

  • North Carolina State University
  • University of Helsinki
  • King Abdulaziz University


In part 1 of this effort (Ind. Eng. Chem. Res. 2011, 50, 12349-12357), we studied how wood dissolved in ionic liquid (IL) is precipitated into different molecular weight ranges upon the addition of a cosolvent. In this article, we further analyze the chemical compositions of these fractions and elucidate the mechanisms of fractionation. Specifically, we fractionated Norway spruce wood solvated with 1-allyl-3-methylimidazolium chloride ([amim]Cl) and analyzed the resulting fractions by Klason lignin analysis and FT-IR and NMR spectroscopies. We found that separation of the different components can be tuned by the variable dissolution of wood based on particle size, resulting from preparatory milling. It is possible to obtain cellulose-rich material with a relatively low (6.2%) lignin content, from spruce sawdust. This can achieved by extracting the cellulose from the insoluble lignin-carbohydrate complex (LCC) matrix. Extensive milling of wood afforded a soluble LCC matrix, and its precipitation was based on molecular weight and not on chemical composition. Indications of the presence of LCCs in the hemicellulose fraction were obtained by utilizing multidimensional NMR spectroscopy.


Original languageEnglish
Pages (from-to)3958-3966
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Issue number11
Publication statusPublished - 20 Mar 2013
MoE publication typeA1 Journal article-refereed

ID: 7030161