不同预处理方法对玉米秸秆酶解性能的影响

摘要

研究了NaOH、Ca(OH)2、NH3·H2 O和NaHSO3等4种化学联合盘磨预处理方法对玉米秸秆酶解性能的影响,考察了不同预处理方法对物料得率、木质素脱除率、还原糖得率、聚糖转化率和结晶度的影响.结果表明,预处理后,玉米秸秆的结晶度均降低.机械盘磨可以减小纤维长度和颗粒尺寸,增大比表面积,暴露出更多的纤维素活性位点,增加纤维素和纤维素酶的反应活性,提高其酶解性能.确定了酶解适宜的条件:纤维素酶用量30 U/g,β-葡萄糖苷酶用量10 U/g,酶解温度50℃和时间72 h,在此条件下NaOH、Ca(OH)2、NH3·H2O和NaHSO3联合盘磨预处理后玉米秸秆的还原糖得率分别为41.00%,23.02%,65.77%和22.22%,聚糖转化率分别为39.04%,18.53%,70.49%和21.33%.在最优条件下,NH3·H2 O联合盘磨预处理玉米秸秆的还原糖得率和聚糖转化率最高,是一种具有前景的预处理方法.%The effects of different chemical pretreatment methods with NaOH, Ca( OH) 2 , NH3·H2 O and NaHSO3 as-sociated with mechanical refining on the enzymatic hydrolysis of corn stalk were evaluated. The solid yield, delignifi-cation rate, reducing sugars yield, polysaccharide conversion and crystallinity of the corn stalk resulted from the four aforementioned pretreatment methods were compared. The crystallinity of the corn stalk decreased after the four pre-treatments, indicating that the crystal structure of the raw materials was damaged to a certain extent during the chemi-cal pretreatment combined with the grinding process. The length of the fibers and size of the corn stalk particles all de-creased while the specific surface area increased after the mechanical disk grinding. More active sites of the cellulose were exposed after the pretreatment, resulting in more adequate contact between cellulose and cellulase, and therefore enhancing the efficiency of the enzymatic process. The optimum enzymatic performance of cellulose was obtained at 50℃ for 72 h with the cellulase and glucosidase doses of 30 U/g and 10 U/g, respectively. Under the optimal condi-tion, the reducing sugars yields of corn stalk from pretreatment by NaOH, Ca(OH)2, NH3·H2O and NaHSO3 associ-ated with mechanical refining were 41.00%, 23.02%, 65.77% and 222.2%, and the polysaccharide conversions were 39.04%, 18.53%,70.49% and 21.33%, respectively. Furthermore, the reducing sugars yield of corn stalk also increased after mechanical refining. Corn stalk pretreated by NH3·H2 O with mechanical refiner gave the highest reduc-ing sugar yield and polysaccharide conversion.