An efficient process for lignin extraction and enzymatic hydrolysis of corn stalk by pyrrolidonium ionic liquids

In recent years, lignocellulosic biomass has drawn increasingly attention as a platform for its transformation into biofuels. However, the complex structures of lignocelluloses limit their conversion into fermentable sugars or other valuable products. In this work, a series of pyrrolidonium-based ionic liquids with a simple synthetic procedure were investigated for the pretreatment of corn stalk at 90 °C for 30 min. Both ionic liquids alone and ionic liquids with deionized water were studied. Fourier transform infrared spectroscopy (FTIR) analysis, scanning electron microscopy (SEM) analysis and nuclear magnetic resonance spectroscopy (NMR) analysis were employed to determine the chemical characteristics of regenerated lignin or cellulosic feedstock. A significant yield of lignin was achieved, as high as 19.07%, which accounted for 85.94% of the original lignin of corn stalk. A high yield of reducing sugar (91.81%) was obtained from regenerated cellulosic feedstock after enzymatic hydrolysis. High yields of glucose (79.63%) and cellobiose (13.66%) were observed as determined by high performance liquid chromatography (HPLC).