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.