title: Facile pretreatment of lignocellulosic biomass at high loadings in room temperature ionic liquids.
abstract: Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3-methylimidizolium acetate ([Emim] [OAc]) at 125 ± 5°C for 1 h resulted in a dramatic reduction of cellulose crystallinity (up to 52%) and extraction of lignin (up to 44%). Enzymatic hydrolysis of the IL-treated biomass was performed with a common commercial cellulase/xylanase from Trichoderma reesei and a commercial β-glucosidase, and resulted in fermentable sugar yields of ∼80% for glucose and ∼50% for xylose at corn stover loadings up to 33% (w/w) and 55% and 34% for glucose and xylose, respectively, at 50% (w/w) biomass loading. Similar results were observed for the IL-facilitated pretreatment of switchgrass, poplar, and the highly recalcitrant hardwood, maple. At 4.8% (w/w) corn stover, [Emim][OAc] can be readily reused up to 10 times without removal of extracted components, such as lignin, with no effect on subsequent fermentable sugar yields. A significant reduction in the amount of IL combined with facile recycling has the potential to enable ILs to be used in large-scale biomass pretreatment.
authors.affiliation: Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Mauricio
authors.initials: M
authors.lastname: Mora-Pale
authors.forename: Jianjun
authors.initials: J
authors.lastname: Miao
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Doherty
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Linhardt
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Dordick
mesh_terms: D018533:Biomass; D002480:Cellulase / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis; D052578:Ionic Liquids / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism; D012997:Solvents; D013696:Temperature; D014242:Trichoderma / Q000201:enzymology; D014994:Xylose / Q000378:metabolism; D003313:Zea mays / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D052578:Ionic Liquids; D011134:Polysaccharides; D012997:Solvents; C036909:lignocellulose; D008031:Lignin; D014994:Xylose; D001617:beta-Glucosidase; D002480:Cellulase; D005947:Glucose