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

Jafari, Yadollah, Amiri, Hamid, Karimi, Keikhosro
Applied energy 2016 v.168 pp. 216-225
Clostridium acetobutylicum, acetic acid, acetone, bagasse, biobutanol, butanol, butyric acid, cost effectiveness, energy, enzymatic hydrolysis, ethanol, ethanol production, fermentation, gasoline, hydrolysates, hydrolysis, lignin, lignocellulose, solvents, sugars, sweet sorghum
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 acetobutylicum for acetone–butanol–ethanol (ABE) production from sweet sorghum bagasse (SSB). Using the pretreatment at 180°C for 60min, the yield of enzymatic hydrolysis of SSB was improved to 94.2%, leading to a hydrolysate with 36.3g/L total sugar, which was subsequently fermented to 11.4g/L ABE. This process resulted in the production of 78g butanol, 35g acetone, 12g ethanol, 28g acetic acid, and 6g butyric acid from each kg of SSB. Through the pretreatment, 143g 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., 24g acetone/kg SSB, using an integrated process for biobutanol production from SSB. The energy equivalent obtained in the form of butanol and ethanol (72g gasoline equivalent/kg SSB) was higher than that obtainable via ethanolic fermentation (less than 70g/kg SSB).