Ionic liquids as efficient pretreatment solvents for lignocellulosic biomass

摘要

Ionic liquid (IL)-assisted pretreatment of lignocellulosic biomass has been extensively studied. Cellulose and hemicelluloses are rich resources of sugars for biofuels. Lignin is a valuable feedstock for aromatic-based platform chemicals. In this study, a series of ionic liquids (ILs) were prepared with one-step synthesis and were investigated for their activity to pretreat lignocelluloses. High yields of lignin (61.0% and 60.4%) were achieved through [Hpy]Cl and [Hmim]Cl pretreatment of poplar. Lignin yields of 51.7% and 50.3% were obtained with a [Hpy]Cl and [Hnmp]Cl pretreatment of bamboo. Improving enzymatic hydrolysis was observed from the regenerated poplar with [Hpy]Cl pretreatment and the regenerated bamboo with [Hmim]Cl pretreatment. The isolated fractions were characterized by FTIR (Fourier transform infrared) spectroscopy. SEM (Scanning electron microscopy) and XRD (X-ray diffractometry) were employed to examine the cellulose-rich materials. A 2D 1H–13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy was employed to analyze lignin fraction. These ionic liquids were particularly effective to extract lignin from lignocelluloses to obtain cellulose-rich materials for biofuels.