Ethanol production from residual lignocellulosic fibers generated through the steam treatment of whole sorghum biomass.

• Cellulosic carbohydrates were recovered from residual sorghum lignocelluloses. • ASTM international and the novel SACH cellulose hydrolysis approaches were compared. • A maximum of 24.3 wt% of cellulosic carbohydrates (dw) were recovered using SACH. • 51.7 wt% total free and constitutive sorghum carbohydrates were recovered. • Fermentation assays suggested 6378 L/ha/year when sorghum was cultivated in Canada. Cellulosic ethanol could play a major role in the upcoming circular-economy once the process complexity, low carbohydrate extraction yields and high costs are resolved. To this purpose, different steam-treatment severity factors were employed on whole sweet sorghum biomass, followed by the delignification and hydrolysis of resulted lignocellulose fibers. A modified ASTM International (American Society for Testing and Material) standard cellulose hydrolysis approach as well as a newly developed SACH (Sulfuric Acid Cellulose Hydrolysis) process were used, recovering up to 24.3 wt% of cellulosic carbohydrates. This amounted to a total extractable and constitutive carbohydrate recovery of 51.7 wt% (dry basis) when a mild steam-treatment of whole sorghum biomass and the SACH cellulose hydrolysis were employed. An ethanol potential of 6378 L/ha/year was determined, comparable to values obtained from biomass such as sugarcane in warmer climates, supporting thus the opportunity of implementing this novel approach on a wider scale. [ABSTRACT FROM AUTHOR]