Characterization of the Glycerol Organosolv Pretreatment of Sugarcane Bagasse

Abstract

Previous work has demonstrated that glycerol organosolv pretreatment can greatly improve the hydrolyzability of various potential lignocellulosic biomass feedstock, sacrificing few polysaccharides during the pretreatment process. This pretreatment strategy is ideal to integrate a commercially successful lignocellulosic and vegetable oil biorefinery industry. However, the pretreatment mechanism has not as yet been elucidated.In this article, an atmospheric aqueous glycerol autocatalytic organosolv pretreatment (AAGAOP) developed at 220^oCfor 2 hr in a 70% aqueous glycerol solution removed 65% lignin and 70% hemicellulose from the sugarcane bagasse, simultaneously with a high cellulose reservation of 95%. Pretreated substrates presented an outstanding hydrolyzability, achieving 90% of the 24 hr enzymatic hydrolysis. With a physicochemical analysis at multidimensional scales, it was demonstrated that the AAGAOP structure chemically modified the lignocellulosic substrate by opening up therecalcitrant architecture of sugarcane bagasse atdifferent scales (macro-, micro- and nano-meter levels), disrupting some of the non-cellulosic components (i.e., lignin, hemicellulose, lignin-carbohydrate complex, and acetyl group), dissolving/relocating the lignin, dissociating the key chemical inter- and intramolecular bonds, and transforming the crystalline cellulose Iβ to paracrystalline or amorphous cellulose. Thereafter, the pretreatment significantly improved the accessibility of cellulose to cellulase enzymes within the pretreated biomass.The glycerol organosolv pretreatment is a promising candidate for the current pretreatment.