Novel pre-treatment and fractionation method for lignocellulosic biomass using ionic liquids

authors	da Silva, SPM; Lopes, AMD; Roseiro, LB; Bogel-Lukasik, R
nationality	International
journal	RSC ADVANCES
keywords	WHEAT-STRAW; ENZYMATIC-HYDROLYSIS; ALKALINE EXTRACTION; CELLULOSE; LIGNIN; HEMICELLULOSES; TEMPERATURE; DISSOLUTION; SOLVENTS; WOOD
abstract	An efficient lignocellulosic biomass pre-treatment is a crucial step for the valorization of these kind of raw materials. Lignocellulosic biomass is a potentially valuable resource for transformation into biofuels and bio-based products. The use of ionic liquids as media for the biomass pre-treatment is an alternative method that follows the green chemistry concept. This work proposes a new methodology for wheat straw pre-treatment with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), which allowed the production of cellulose, hemicellulose and lignin-rich fractions in a rapid and simple three-step fractionation process. Various temperatures (80-140 degrees C) and processing times (2-18 h) of the pretreatment were studied. The quantitative and qualitative analysis of each lignocellulosic biomass fraction was determined by FTIR measurements. The glucan content in recovered cellulose-rich fractions was investigated by enzymatic hydrolysis. The cellulose recovery dependence on the pre-treatment conditions was ascertained through regression analysis. The optimal result for the recovery of the cellulose-rich fraction was obtained at 140 degrees C during 6 h achieving 37.1% (w/w) of the initial biomass loading. For the same conditions, optimal results were also produced regarding the amount of glucan present (81.1% w/w(biomass)) in cellulose-rich fractions, the carbohydrate enrichment in the hemicellulose fraction (96% wt) and the purity of lignin (97% wt). The recovery of IL was performed after each pre-treatment and the obtained yields were up to 86% (w/w). The recovered ILs were analyzed by C-13 and H-1 NMR. The presence of value-added phenolic compounds in the recovered ILs was analyzed by capillary electrophoresis. Vanillin and its derivatives, as well as other lignin-based products, were identified.
publisher	ROYAL SOC CHEMISTRY
issn	2046-2069
year published	2013
volume	3
issue	36
beginning page	16040
ending page	16050
digital object identifier (doi)	10.1039/c3ra43091j
web of science category	Chemistry, Multidisciplinary
subject category	Chemistry
unique article identifier	WOS:000323271700068