Study On Process And Mechanism Of SO₃Micro-thermal Explosion Pretreatment Of Wheat Straw

This paper is based on the existing SO3micro thermal explosion collaborativedilute alkali treatment method of the laboratory, further investigates the factorsaffecting of SO3micro thermal explosion treatment and analyzes the causes and waysof SO3micro thermal explosion treatment. The main points are as follows：1．Hexane can peel the waxy of wheat straw surface, but it will cause the loss ofwheat straw, the loss rate of3.83%, and the residual hexane could undermine thevitality of the center of the cellulase,it will be bad for enzymatic saccharification.2．Pretreatment time of SO3micro-thermal explosion has a significant effect onthe chemical structure, functional groups, spatial structure and the subsequentsaccharification of wheat straw. Along with the increase of pretreatment time,813cm-1place C-O-S vibrating peaks appear on the IR spectrum. However,when thepretreatment time is short, we can’t find813cm-1place C-O-S vibrating peaks,Itsuggested the hydration reaction happened prior to sulfuric acid esterification.3．we investigated SO3micro-thermal explosion pretreatment time, pretreatmenttemperature, fuming sulfuric acid dosage and straw moisture, selected the cellulosecontent and the final saccharification rate as the targets for optimal the processes, afteranalysis, the optimal conditions is the liquid ratio between rice straw and SO3was1:5,temperature60℃, treat120min;moisture5%. In the optimal conditions, the contentof straw cellulose is large to64.72%,lignin is6.63%, the final saccharification rate ofup to90.21%.4．We employed the technologies of FI-TR, XPS and SEM to study the wheatstraw characterization, functional groups, the content of S and the morphology ofwheat straw before and after SO3combine dilute alkali pretreatment, By comparingthese factors, we can systematically sum up all that is related to the pretreatmentmechanism of SO3micro-thermal explosion.At first, through the gas diffusion, SO3reacted with water, and gave off heat,when this sum reached a certain criticalthreshold,It could break the rigid straw stalks, this is helpful to increase strawporosity and specific surface area. With the advance of pretreatment time,sulfuric acidinterrupted the hydrogen bonding between lignin and cellulose and hemicellulose, andreacted with the alcohol hydroxyl of lignin.Sulfur esterification reaction could breakthe chemical structure of lignin, improve the effect of the lignin stripping, and begood for enzyme saccharification. 5．Through the study of cellulose enzymatic saccharification, With the increaseof enzymatic saccharification time,originally strip, smooth, parallel beam of cellulosestructure, gradually become velvet, Through hydrolyzation, acetate fiber’s surface wasdenuded by cellulase enzyme.The space of the cellulose structure collapsed,cellulosechain completely was distorted through XPS analysis of the enzymatic hydrolysisresidue showed that the content of C increased, that the content of O is lower.