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Switchable Ionic Liquids as Delignification Solvents for Lignocellulosic Materials

Authors

  • Ikenna Anugwom,

    1. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)
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  • Dr. Valerie Eta,

    1. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)
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  • Dr. Pasi Virtanen,

    1. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)
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  • Dr. Päivi Mäki-Arvela,

    1. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)
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  • Mattias Hedenström,

    1. Computation Life Science Cluster (CLIC), Department of Chemistry, Chemical–Biological Center, Umeå University, 901 87, Umeå (Sweden)
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  • Dr. Michael Hummel,

    1. Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, 00076 Aalto (Finland)
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  • Prof. Herbert Sixta,

    1. Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, 00076 Aalto (Finland)
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  • Prof. Jyri-Pekka Mikkola

    Corresponding author
    1. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)
    2. Technical Chemistry, Department of Chemistry, Chemical-Biological Center, Umeå University, 901 87, Umeå (Sweden)
    • Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland)===

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Abstract

The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B. pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2-SIL treatment resulted in 80 wt % cellulose, 10 wt % hemicelluloses, and 3 wt % lignin, whereas MEA-CO2-SIL treatment resulted in 66 wt % cellulose, 12 wt % hemicelluloses and 11 wt % lignin. Thus, the MEA-SO2-SIL proved more efficient than the MEA-CO2-SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), 13C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).

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