How Alkyl Chain Length of Alcohols Affects Lignin Fractionation and Ionic Liquid Recycle During Lignocellulose Pretreatment

Noppadon Sathitsuksanoh, Manali Sawant, Quoc Truong, Jared Tan, Christian Canlas, Ning Sun, Wei Zhang, Scott Renneckar, Teerawit Prasomsri, Jian Shi, Özgül Çetinkol, Seema Singh, Blake A. Simmons, Anthe George*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Alcohols of increasing alkyl chain length were investigated as precipitants in an ionic liquid (IL) pretreatment system. Switchgrass samples pretreated by 1-ethyl-3-methylimidazolium acetate were characterized after the use of different alkyl chain lengths of alcohols as antisolvents. The resulting IL-pretreated switchgrass (PSG) samples were characterized by enzymatic hydrolysis, cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and 2D NMR spectroscopy. Glucan digestibilities of PSG samples were ∼80 % after 72 h at 5 mg protein g−1 glucan regardless of the antisolvent used. The use of 1-octanol as an antisolvent, with 10 % water to allow for use of wet biomass, enabled a partial lignin fractionation and multiphase separation for the IL recycle without compromising the chemical structure of the carbohydrates and lignin from the PSG. Lignin fragments were observed in the IL after pretreatment by gel permeation chromatography (GPC). After separation, both the IL and the octanol antisolvent were reused for switchgrass pretreatment and precipitation for an additional 3 cycles. The PSG samples derived from recycled IL were rapidly hydrolyzed, and a high glucan digestibility of 80 % was obtained even at a low enzyme loading of 5 mg protein g−1 glucan. 2D NMR analysis of residual solids of PSG post-enzymatic hydrolysis revealed that lignin in these residual solids was depolymerized. This strategy enables an ease in separation of pretreated lignocellulosic solids, reduced water use, and recycle of both IL and the antisolvent.

Original languageEnglish (US)
Pages (from-to)973-981
Number of pages9
JournalBioenergy Research
Volume8
Issue number3
DOIs
StatePublished - Sep 8 2015

Keywords

  • Biofuels
  • Ionic liquid recycle
  • Ionic liquids
  • Lignin
  • Pretreatment

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Agronomy and Crop Science
  • Energy (miscellaneous)

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