水热预处理工艺参数对玉米秸秆组分与酶解效率的影响

采用间歇式水热预处理方法,考察了不同水热预处理温度和处理时间对玉米秸秆主要成分变化的影响以及水热预处理后的纤维素酶解效率。在180～220℃,10～25 min范围内,随温度升高和时间延长预处理后半纤维素移除率和纤维素损失率也随之增大,但木质素质量并未减少反而有所增加。在210℃,25 min时得到最大半纤维素移除率为86.0%。以半纤维素移除率、木质素移除率和纤维素损失率为因变量,处理温度和处理时间为自变量通过多元线性回归分析或二次方程(多元线性回归方程拟合度不佳时)拟合分别获得回归模型。模型显示处理温度和处理时间对三者均具有显著影响。分析敏感性显示处理温度对三种因变量的影响均大于处理时间。经210℃,20 min处理后,纤维素酶解率最高为76.2%,继续提高处理温度和延长处理时间半纤维素移除率提高,但纤维素酶解率下降。

Effects of liquid hot water pretreatment process parameters on components and cellulose digestibility of corn stover

Corn stover was pretreated with liquid hot water (LHW) method using a batch rector in order to enhance cellulose digestibility. The effects of pretreatment process parameters (pretreatment temperature 180-220℃, reaction time 10-25 min) on the main components (hemicellulose, lignin, and cellulose) and cellulose digestibility were investigated. Multiple linear regression models or quadratic equation models (only for lignin removal) were established by analyzing hemicellulose removal, lignin removal, and cellulose loss as dependent variables and pretreatment temperature and reaction time as independent variables. Hemicellulose removal and cellulose loss increased with increasing pretreatment temperature and reaction time over the range of experimental conditions. Compared to lignin in raw corn stover, mass of lignin in pretreated corn stover increased (lignin removal was negative), also as a function of increasing pretreatment temperature and reaction time, probably because of the formation of pseudo-lignin. Sensitivity analyses showed that the significance level of pretreatment temperature was much higher than that of the reaction time on these three dependent variables. The maximum enzymatic digestibility (76.2%) of cellulose in raw corn stover was achieved after the pretreatment (210℃, 20 min). Higher severity conditions caused more hemicellulose removal, as well as more cellulose loss, thus lowering the enzymatic digestibility of cellulose in raw corn stover.