Combined approaches to obtain cellulose nanocrystals, nanofibrils and fermentable sugars from elephant grass

This work is focused in methodologies to obtain cellulose nanocrystals, cellulose nanofibrils, soluble lignin and fermentable sugars from elephant grass, aiming a more integral use of this biomass. To improve hydrolysis, three different pretreatments for biomass delignification and bleaching were compared: 1. Concentrated alkaline peroxide (CP); 2. Diluted alkaline peroxide (DP); and 3. Acid-alkali (AA) pretreatment. Cellulose nanocrystals were obtained from elephant grass leaves by acid hydrolysis, with a 12-16% w/w yield considering the initial biomass weight, and presented high crystallinity index (CI=72-77%) and aspect ratios (30-44), depending on the pretreatment approach. Together with the cellulose nanocrystals, other useful by-products were obtained, such as cellulose nanofibrils (3.8%-9.7% w/w yield), extractives (12.3%), liquors rich in hydrolysed lignin (16.0-21.1%) and sugars (22.1-25.2%). The results presented herewith should contribute to the economic viability and the sustainability of this biomass fractionation process.