Enhancement of cellulose hydrolysis in sugarcane bagasse by the selective removal of lignin with sodium chlorite

Abstract

Lignocellulosic materials are rich in cellulose, which can be hydrolyzed into glucose. However, this polysaccharide is associated with lignin and hemicellulose, materials that limit its conversion. The objective of this work was to selectively remove lignin from sugarcane bagasse with sodium chlorite/acetic acid to produce model substrates with lower levels of this component. Control bagasse contained 22.8% of lignin, and after 4h of delignification, materials with up to 6.8% of lignin were obtained, retaining the cellulosic and hemicellulosic contents almost unchanged. The pretreated samples of sugarcane bagasse were subjected to enzymatic hydrolysis with commercial cellulases. Bagasse samples with lower lignin content were more easily digested by these enzymes. When supplemented with β-glucosidase, the entire cellulose fraction from the 3- and 4-h treated bagasse was hydrolyzed. Cellulose conversion levels higher than 80% were obtained when lignin removals were higher than 60%. Even higher conversions were reached after removing 70% of the lignin.