Complete dissolution and partial delignification of wood in the ionic liquid 1-ethyl-3-methylimidazolium acetate

Abstract

Both softwood (southern yellow pine) and hardwood (red oak) can be completely dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C 2 mim]OAc) after mild grinding. Complete dissolution was achieved by heating the sample in an oil bath, although wood dissolution can be accelerated by microwave pulses or ultrasound irradiation. It has been shown that [C 2 mim]OAc is a better solvent for wood than 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl) and that variables such as type of wood, initial wood load, particle size, etc. affect dissolution and dissolution rates; for example, red oak dissolves better and faster than southern yellow pine. Carbohydrate-free lignin and cellulose-rich materials can be obtained by using the proper reconstitution solvents (e.g., acetone/water 1 : 1 v/v) and approximately 26.1% and 34.9% reductions of lignin content in the reconstituted cellulose-rich materials (from pine and oak, respectively) have been achieved in one dissolution/reconstitution cycle. The regenerated cellulose-rich materials and lignin fractions were characterized and compared with the original wood samples and biopolymer standards. For pine, 59% of the holocellulose (i.e., the sum of cellulose and hemicellulose) in the original wood can be recovered in the cellulose-rich reconstituted material; whereas 31% and 38% of the original lignin is recovered, respectively, as carbohydrate-free lignin and as carbohydrate-bonded lignin in the cellulose-rich material.

Ionic liquids as coagents for sulfur vulcanization of butadiene–styrene elastomer filled with carbon black

“…In the past few years, ILs have also been employed as solvents for various types of polymerization [21][22][23], to dissolve polymers (cellulose [24], silk fibroin [25], starch [26]) or as plasticizers for different polymers [27,28].…”

Ionic liquid-tolerant microorganisms and microbial communities for lignocellulose conversion to bioproducts

“…Used as a pretreatment regime, ILs have been demonstrated to be effective on a variety of biomass sources, such as switchgrass, corn stalk, rice straw, bagasse, sugarcane, pine wood, maple wood, hardwood red oak, and mixtures of softwoods (Fort et al 2007;Kilpelainen et al 2007;Lee et al 2009;Li et al 2010;Li et al 2008;Singh et al 2009;Sun et al 2009;Tan et al 2009;Trinh et al 2015). They are also becoming more cost-effective as compared to other pretreatment options (George et al 2015).…”

“…For example, the degrees of crystallinity in cellulose reconstituted after being dissolved in 1-allyl-3-methylimidazolium chloride ([C 3 C 1 Im]Cl) and 1-butyl-3-methylimidazolium chloride ([C 4 C 1 Im]Cl) were lower than untreated cellulose, resulting in an increased accessibility of the polysaccharide chains to cellulases (Dadi et al 2007;Dadi et al 2006;Liu and Chen 2006). A reduction in crystallinity was observed after IL pretreatment of switchgrass, maple wood, yellow pine, and hardwood red oak (Lee et al 2009;Li et al 2010;Sun et al 2009). Moreover, in IL pretreated biomass samples, cellulose can be easily recovered with the addition of anti-solvents, such as water, methanol, ethanol, and acetone, and the enzymatic hydrolysis of the recovered cellulose is much greater than that of untreated cellulose (da Costa Lopes et al 2013;Dadi et al 2006;Lee et al 2009;Li et al 2009;Singh et al 2009;Sun et al 2009;Zhao et al 2009a).…”

“…A reduction in crystallinity was observed after IL pretreatment of switchgrass, maple wood, yellow pine, and hardwood red oak (Lee et al 2009;Li et al 2010;Sun et al 2009). Moreover, in IL pretreated biomass samples, cellulose can be easily recovered with the addition of anti-solvents, such as water, methanol, ethanol, and acetone, and the enzymatic hydrolysis of the recovered cellulose is much greater than that of untreated cellulose (da Costa Lopes et al 2013;Dadi et al 2006;Lee et al 2009;Li et al 2009;Singh et al 2009;Sun et al 2009;Zhao et al 2009a). …”

Recovery of Sugars from Ionic Liquid Biomass Liquor by Solvent Extraction

“…The IL 1-ethyl-3-methylimidazolium acetate ( Fig. 1), abbreviated as [C2mim][OAc], has been found to be one of the most promising candidates for biomass pretreatment [27,35].…”