Study On The Separation Of Fibrous Components Of Pennisetum Sinese Based On Hemicellulose Enzymatic Hydrolysis

As the carrier of biomass energy,green plants can be used to develop and produce biological products or the required bioenergy.In recent years,as a good lignocellulosic material,Pennisetum sinese has received increasing attention.It is a tall perennial plant with elevated stress resistance,high crude protein and sugar content and can be planted in several areas.At present,Pennisetum sinese is mainly used for fodder,edible fungus culture or biogas production,etc.The utilization rate of each component is low,generating more waste.In this study,based on the enzymatic hydrolysis of hemicellulose,the components of Pennisetum sinese were separated.The following aspects were explored:（1）The degradation of lignin in Pennisetum sineseAfter sodium hydroxide pretreatment,the lignin in the solution was separated and degraded by Electric-Fenton and white rot fungi.The results showed that the activities of manganese peroxidase（Mn P）,lignin peroxidase（Li P）and laccase（Lac）increased with the increase of current within 96 h.The activity of Mn P was the most significant and increased rapidly to 402 U/L at 0.3 A.In the synergistic system,the degradation rate of lignin reached 84.5%,while the degradation rate of lignin was only 9.1%when Electric-Fenton was used alone.This proves that Electric-Fenton and white rot fungi have a good synergistic effect on lignin.The functional group changes before and after lignin degradation were analyzed by HSQC-NMR,and the mechanism of lignin degradation by the synergistic system was studied.The results showed that the functional groups of lignin treated by the synergistic system were significantly reduced,especially in the aromatic and aliphatic regions.（2）Compound hemicellulase hydrolyzed Pennisetum sineseXylanase,hemicellulase and arabinofuranosidase were used to hydrolyze Pennisetum sinese to extract the Pennisetum sinese fiber.The optimal dosage of the three enzymes were 450 U/g,240 U/g and 315 U/g,respectively.When treated with xylanase alone,the degradation rate of hemicellulose was 52.76%.When the three enzymes acted together,the degradation rate of hemicellulose increased by 9.19%.Obviously,the addition of branch-chain enzyme promoted the hydrolysis of hemicellulose,but it did not improve significantly.In addition,there was no significant change in the degradation efficiency of hemicellulose by changing the order of addition of the three enzymes,however,the effect of adding xylanase first and then adding the other two enzymes is better than the other sequences.Finally,the structure and morphological changes of the different treatments were characterized by FTIR,XRD and ¹³C CP/MAS solid state NMR.（3）Extraction and characterization of microcrystalline cellulose from Pennisetum sineseAfter compound enzyme treatment,the samples were bleached and hydrolyzed with hydrochloric acid.The results showed that the optimum bleaching time was 80 min,the bleaching temperature was 80℃,and the concentration of sodium hypochlorite was 6%（w/v）.At this time,the whiteness of the sample was 80.21%.When the optimal hydrolysis temperature was 85℃,time was90 min,hydrochloric acid concentration was 1.5 mol/L,the purity of microcrystalline cellulose was90.18%,the p H was 5.5～5.7,and the degree of polymerization was 245.Finally,the microcrystalline cellulose of Pennisetum sinese was characterized.Through scanning electron microscopy,infrared spectroscopy,x-ray diffraction and thermal analysis,concluding that the MCC of Pennisetum sinese was in the form of rod-like fiber.After treatment,lignin and hemicellulose were largely removed,and the crystallinity of the MCC of Pennisetum sinese reached 70.22%and had good thermal stability.