Assessing the Facile Pretreatments of Bagasse for Efficient Enzymatic Conversion and Their Impacts on Structural and Chemical Properties

Here, novel and sustainable pretreatment approaches are desired to improve the techno-commercial feasibility of biorefineries in the future. In this study, 10 renewable deep eutectic solvents (DESs) were evaluated for their pretreatment efficiency at facile conditions with sugar cane bagasse as substrate and compared with conventional pretreatment approaches (dilute alkali, dilute acid, and ionic liquid (IL)) for lignin removal, saccharification yield, cellulose accessibility, crystallinity, and physiochemical properties. Although, the highest delignification was obtained with dilute alkali (59.7%) and choline chloride:lactic acid or ChCl:LA (50.6%), the maximum enzymatic conversion of 98.0% and 90.4% was observed with IL (1-butyl-3-methylimidazolium acetate) and ChCl:LA, respectively. uclear magnetic resonance analysis of ChCl:LA-derived lignin showed selective removal of guaiacyl lignin without condensation structure formation observed. Interestingly, unlike IL, the lignin was substantially depolymerized after ChCl:LA pretreatment as determined by gel permeation chromatography. Further, high compatibility of ChCl:LA with cellulase in comparison of IL with easy recyclability and recycling showed that DESs synthesized from a renewable resource are promising “green” solvents for future biorefinery operations.