Structural Analysis of Alkaline Pretreated Rice Straw for Ethanol Production

• Published in: International Journal of Polymer Science Vol. 2017; no. 2017; pp. 1 - 9
• Main Authors: Teeravivattanakit, Thitiporn, Baramee, Sirilak, Permsriburasuk, Chutidet, Phitsuwan, Paripok, Ratanakhanokchai, Khanok
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Publishing Corporation 01.01.2017; Hindawi; John Wiley & Sons, Inc; Wiley
• Subjects: Acids; Agricultural wastes; Alcohol; Alcohol, Denatured; Alternative energy sources; Ammonia; Biochemistry; Biodiesel fuels; Biomass; Biotechnology; Carbohydrates; Cellulase; Cellulose; Cellulose fibers; Chemical composition; Crystallinity; Dextrose; Enzymes; Ethanol; Fermentation; Glucan; Glucose; Hydrolysis; Lignin; Lignocellulose; Porosity; Pretreatment; Production data; Raw materials; Refining; Saccharification; Silicon dioxide; Statistical analysis; Straw; Structural analysis; Thailand
• ISSN: 1687-9422; 1687-9430
• DOI: 10.1155/2017/4876969

Rice straw (RS) is an abundant, readily available agricultural waste, which shows promise as a potential feedstock for Asian ethanol production. To enhance release of glucose by enzymatic hydrolysis, RS was pretreated with aqueous ammonia (27% w/w) at two pretreatment temperatures: room temperature and 60°C. Statistical analysis indicated similarity of enzymatic glucose production at both pretreatment temperatures after 3-day incubation. Chemical composition, FTIR, and EDX analyses confirmed the retention of glucan and xylan in the pretreated solid, but significant reduction of lignin (60.7% removal) and silica. SEM analysis showed the disorganized surfaces and porosity of the pretreated RS fibers, thus improving cellulose accessibility for cellulase. The crystallinity index increased from 40.5 to 52.3%, indicating the higher exposure of cellulose. With 10% (w/v) solid loadings of pretreated RS, simultaneous saccharification and fermentation yielded a final ethanol concentration of 24.6 g/L, corresponding to 98% of maximum theoretical yield. Taken together, aqueous ammonia pretreatment is an effective method to generate highly digestible pretreated RS for bioethanol production and demonstrates potential application in biorefinery industry.