Facile and Simple Pretreatment of Sugar Cane Bagasse without Size Reduction Using Renewable Ionic Liquids–Water Mixtures

In this work, sugar cane bagasse pretreatment by renewable cholinium amino acids ionic liquids ([Ch][AA] ILs) and subsequent enzymatic hydrolysis of the residues were conducted. Six ILs tested were found to be effective for sugar cane bagasse pretreatment. Upon pretreatment using these ILs, the enzymatic digestion of this lignocellulosic biomass was improved significantly due to extensive delignification. The IL cholinium lysine ([Ch][Lys]) displayed excellent pretreatment efficiency with sugar cane bagasse of various sizes as the substrates. The addition of water into [Ch][Lys] did not exert a negative effect on pretreatment effectiveness, although the delignification capacity of the IL decreased. The sugar yields of 80% for glucose and 84% for xylose were obtained in the enzymatic hydrolysis after the sugar cane bagasse without size reduction was pretreated with a biomass loading of 5 wt % by 50 g 50% [Ch][Lys]–water mixture at 90 °C for 6 h. A simple and atom-economic preparation approach to ILs was successfully developed for lignocellulosic biomass pretreatment, which may significantly reduce ILs costs, and the reactant contaminations in the IL–water mixture had no detrimental effect on the pretreatment efficiency.