水热-乙醇提取处理玉米秸秆促进酶解效率

Enhancement of Enzymatic Hydrolysis of Corn Stover by Liquid Hot Water Pretreatment and Ethanol Extraction

针对水热预处理不能明显移除木质素、木质素在较高温条件下从细胞壁中分解游离并重新聚合的特点,采用水热-乙醇提取处理玉米秸秆,与水热预处理的效果进行了对比,并对乙醇过程进行了优化。结果表明:水热-乙醇提取能够移除部分木质素,提高预处理后固体中纤维素含量以及纤维素的酶解效率,水热-乙醇提取后秸秆的木质素移除率随水热预处理温度的增加而增大。乙醇提取的较优工艺条件是液固比25、室温、120 r·min-1,提取10 h。经210℃、20 min预处理的秸秆再经乙醇提取后,酸不溶木质素含量由30.5%下降为18.2%,纤维素含量由62.2%提高到73.6%,酶解率为93.2%(15 FPU·g-1纤维素),酶解时间由48 h缩短至24 h。

Lignin could not be significantly removed from lignocellulose by liquid hot water(LHW) pretreatment, but lignin would mi-grate from cell wall and redeposit on the surface of cell wall at high temperature during pretreatment. To take advantage of this characteristic, we examined the changes of main components and enzymatic hydrolysis of corn stover pretreated by LHW pretreatment before and after ethanol extraction.Ethanol extraction process was also optimized. Compared to LHW pretreatment, ethanol extraction removed some lignins from, increased cellulose content in and improved cellulose digestibility of corn stover. Lignin removal increased with increasing temperature of LHW pretreatment. The optimal ethanol extraction was as follows:25 of liquid-solid ratio, room temperature, 120 r·min-1, and 10 h. For corn stover pretreated at 210 ℃ for 20 min, ethanol extraction decreased lignin from 30.5% to 18.2%, while increased cellulose content from62.2% to 73.6%. After ethanol extraction, the enzymatic hydrolysis time was shortened from 48 h to 24 h. The cellulose digestibility reached93.2%(15 FPU·g-1 cellulose).