Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose

Abstract

Ionic liquids (ILs), solvents composed entirely of paired ions, have been used in a variety of process chemistry and renewable energy applications. Imidazolium-based ILs effectively dissolve biomass and represent a remarkable platform for biomass pretreatment. Although efficient, imidazolium cations are expensive and thus limited in their large-scale industrial deployment. To replace imidazolium-based ILs with those derived from renewable sources, we synthesized a series of tertiary amine-based ILs from aromatic aldehydes derived from lignin and hemicellulose, the major byproducts of lignocellulosic biofuel production. Compositional analysis of switchgrass pretreated with ILs derived from vanillin, p-anisaldehyde, and furfural confirmed their efficacy. Enzymatic hydrolysis of pretreated switchgrass allowed for direct comparison of sugar yields and lignin removal between biomass-derived ILs and 1-ethyl-3-methylimidazolium acetate. Although the rate of cellulose hydrolysis for switchgrass pretreated with biomassderived ILs was slightly slower than that of 1-ethyl-3-methylimidazolium acetate, 90-95% glucose and 70-75% xylose yields were obtained for these samples after 72-h incubation. Molecular modeling was used to compare IL solvent parameters with experimentally obtained compositional analysis data. Effective pretreatment of lignocellulose was further investigated by powder X-ray diffraction and glycome profiling of switchgrass cell walls. These studies showed different cellulose structural changes and differences in hemicellulose epitopes between switchgrass pretreatments with the aforementioned ILs. Our concept of deriving ILs from lignocellulosic biomass shows significant potential for the realization of a "closed-loop" process for future lignocellulosic biorefineries and has far-reaching economic impacts for other IL-based process technology currently using ILs synthesized from petroleum sources. renewable chemicals | bioenergy | lignocellulose conversion | saccharification | green chemistry

Integrating a Biorefinery into an Operating Kraft Mill

“…Hemicellulose films obtained from ionic liquid pretreatment gave better oxygen barrier properties than those prepared from cold caustic extraction (Laine et al 2016). Reductive amination of aldehydes obtained from degradation products of lignin and hemicellulose could be used to make tertiary amines that form the cationic component of low cost ionic liquids (Socha et al 2014). Finding effective lowcost ionic liquids and recovering them in high yield are major challenges in commercializing their use in biomass fractionation (Baral and Shah 2016).…”

Bioenergy Based Power Sources for Mobile Autonomous Robots

“…To increase the speed of these processes, several studies now on thermostable enzymes' usage [114][115][116] and pretreatment stage effectivization [112] are under way. A very promising solution is the use of ionic liquids for biomass pretreatment [117][118][119]. Ionic liquids are composed mostly of ions.…”

Ionic Liquids Treated within the Grand Canonical Adaptive Resolution Molecular Dynamics Technique

“…By chemical modification of the polar or apolar components or charge of the ions, numerous ILs with a range of physicochemical properties such as viscosity, catalytic activity, or solvation can be generated. We now have task specific ionic liquids that can be applied for a range of designated applications [4,5]: ionic liquids as drugs [6,7], as batteries and super-capacitors for solving energy demands of the environment [8][9][10][11], to capture greenhouse gases, to dissolve proteins [12,13] and cellulose [14,15].…”