The production of fermentable sugar and bioethanol from acacia wood by optimizing dilute sulfuric acid pretreatment and post treatment

• Published in: Fuel (Guildford) Vol. 275; p. 117943
• Main Authors: Lee, Ilgyu, Yu, Ju-Hyun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2020; Elsevier BV
• Subjects: Acacia; Bioethanol; Biofuels; Conversion; Dilute sulfuric acid pretreatment; Dilution; Enzymatic hydrolysis; Ethanol; Fermentable sugar; Glucan; Glucose; Hardwoods; Hemicellulose; Hydrolysis; Hydrothermal treatment; Lignin; Optimization; Pretreatment; Sugar; Sulfuric acid; Yield; Bioethanol; Hydrothermal treatment; Fermentable sugar; Enzymatic hydrolysis; Acacia; Dilute sulfuric acid pretreatment
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2020.117943

•Potential of acacia wood as a raw material for sugar production has been proved.•Maximum glucose yield was carried out with 0.05% sulfuric acid at 200 °C for 5 min.•Dilute acid treatment was compared to hydrothermal treatment for sugar conversion.•Mechanical refining and addition of soy protein improved enzymatic digestibility.•The value of the produced fermentable sugar was demonstrated by yeast fermentation. Dilute sulfuric acid pretreatment was applied to make acacia wood susceptible to enzymatic hydrolysis. The optimal conditions for pretreatment were determined using a statistical approach; the maximum glucose yield (predicted: 53.8%; experimental: 54.5%) was obtained with 0.05% sulfuric acid at 200 °C for 5 min. This optimal condition yielded higher hemicellulose recovery in a short time compared to hydrothermal treatment, but the glucose yield was not enough to make fermentable sugar. However, application of mechanical refining to the pretreated solid and the addition of soy protein to the enzymatic hydrolysis led to the highest glucose conversion (73.8%) at 10 FPU (Cellic® CTec3)/g of glucan, and maximum conversion yield to ethanol reached 94.9% at 5 FPU. Considering this method’s comparable glucose convertibility, even from lignin rich woody biomass, ability to recover hemicellulose, and lower enzyme requirement, dilute acid pretreatment can serve as a direct and promising route of producing acacia sugar.