title: Switchable ionic liquids as delignification solvents for lignocellulosic materials.
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), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).
authors.affiliation: Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500 (Finland).
authors.forename: Ikenna
authors.initials: I
authors.lastname: Anugwom
authors.forename: Valerie
authors.initials: V
authors.lastname: Eta
authors.forename: Pasi
authors.initials: P
authors.lastname: Virtanen
authors.forename: Päivi
authors.initials: P
authors.lastname: Mäki-Arvela
authors.forename: Mattias
authors.initials: M
authors.lastname: Hedenström
authors.forename: Michael
authors.initials: M
authors.lastname: Hummel
authors.forename: Herbert
authors.initials: H
authors.lastname: Sixta
authors.forename: Jyri-Pekka
authors.initials: JP
authors.lastname: Mikkola
mesh_terms: D029662:Betula / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D019856:Ethanolamine / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry; D014934:Wood / Q000737:chemistry*
chemical_list: D052578:Ionic Liquids; D013458:Sulfur Dioxide; C036909:lignocellulose; D002245:Carbon Dioxide; D019856:Ethanolamine; D008031:Lignin
keywords: alkanol amines; biomass; delignification; ionic liquids; organic superbases