Formic Acid-Based Organosolv Delignification of Sugarcane Bagasse for Efficient Enzymatic Saccharification

Sugarcane bagasse, a major by-product from cane sugar industry contains mainly cellulose, lignin and hemicellulose which can be fractionated and used for further products. In this study, an organosolv fractionation based on formic acid was used to pretreat the sugarcane bagasse, separate, and recover cellulose. A central-composite matrix with three independent variables (formic acid concentration, temperature, and fractionation time) was designed to study their simultaneous effects on the delignification, purity of recovered cellulose. Temperature was found to be the main factor affecting the fractionation process, following the formic acid concentration and fractionation time. The fractionation process removed not only lignin and hemicellulose from sugarcane bagasse but also altered the crystallinity of cellulose to facilitate the glucan hydrolysis. The fractionation temperature and delignification were inversely proportional to the crystallinity of the recovered cellulose (R2 = 0.99 and 0.83, respectively), regardless the formic acid concentration used. There was a strong linear correlation between delignification and hydrolysis ability of the fractionated glucan. The formic acid-based fractionation removed 90.6% lignin, resulted in recovered relatively pure cellulose with 92.3% glucan which enzymatic saccharification ability was achieved 91.4% to produce fermentable sugars.