Simultaneous saccharification and fermentation of one-step fractionated lignocellulose for very high gravity ethanol production

• Main Authors: Nai-yi Wang, 王迺詒
• Other Authors: Cheng-kang Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/ra75zr

碩士 === 國立臺灣科技大學 === 化學工程系 === 100 === One-pot fractionation of cellulose-pulp, soluble hemicelluloses sugars and lignin from waste bamboo chopstick was carried out at mild temperatures of 140℃ by using oxalic acid aqueous solution and a organic phase consisting of bio-based 2-methyl tetrahydrofuran (2-MTHF). Lignin was enriched in the organic phase while most of hemicelluloses was depolymerized into xylose and existed in aqueous phase. The remaining solid phase (P) was mostly cellulose pulp. The cellulose content of the solid phase was enriched from 44％ to 73％(w/w) after fractionation. Several pretreatment methods such as IL dissolution, concentrated phosphoric acid dissolution, and NaOH mercerization were applied on P to enhance its enzymatic hydrolysis. NaOH mercerization at 50 oC for 3 h was demonstrated to be a facile pretreatment method which can make P to have similar hydrolysis rate and yield as compared with other methods. The spent NaOH solution can be easily separated from P and recycled for mercerization at least 3 times without affecting its hydrolysis rate and yield. Approximately, cellulose content of 20g/L of P can generate 15.4 g/L glucose after mercerization pretreatment. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was employed to study the adsorption behaviors of Accellerase-1500 on microcrystalline cellulose and cellulose-extracted from bamboo chopsticks through NaOH mercerization pretreatment (P+N). The P+N substrate demonstrated a superior cellulase binding capability to that of P and microcrystalline cellulose. Based on the SDS-PAGE cellulase binding analysis, SEM observation and XRD analysis, the enhanced hydrolysis of P after mercerization pretreatment could attribute to the disrupted crystal structure and increased surface area, which made the cellulose better accessible for enzymatic hydrolysis. Saccharomyces cerevisiae was employed for simultaneous saccharification and fermentation (SSF) of P+N substrate for ethanol production. P+N substrate of 230g/L was employed for SSF and 76.4g /L of ethanol was obtained after 3 day with 82.5％cellulose conversion rate.