Acetone pretreatment for improvement of acetone, butanol, and ethanol production from sweet sorghum bagasse

Development of efficient and cost-effective pretreatment prior to hydrolysis is essential for the economical production of biobutanol from lignocelluloses. In this study, acetone pretreatment with a number of advantages over the other pretreatments was used to improve enzymatic hydrolysis and fermentation with Clostridium acetolnitylicum for acetone-butanol-ethanol (ABE) production from sweet sorghum bagasse (SSB). Using the pretreatment at 180 degrees C for 60 min, the yield of enzymatic hydrolysis of SSB was improved to 94.2%, leading to a hydrolysate with 36.3 g/L total sugar, which was subsequently fermented to 11.4 g/L ABE. This process resulted in the production of 78 g butanol, 35 g acetone, 12 g ethanol, 28 g acetic acid, and 6 g butyric acid from each kg of SSB. Through the pretreatment, 143 g lignin per kg of SSB was dissolved into the solvent, with the potential to be recovered as unaltered pure lignin. Furthermore, the co-production of acetone by the ABE fermentation alleviated the concern about unavoidable solvent loss in the pretreatment, i.e., 24 g acetone/kg SSB, using an integrated process for biobutanol production from SSB. The energy equivalent obtained in the form of butanol and ethanol (72 g gasoline equivalent/kg SSB) was higher than that obtainable via ethanolic fermentation (less than 70 g/kg SSB). (C) 2016 Elsevier Ltd. All rights reserved.