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Optimization Of Enzymatic Hydrolysis Of Wood Fiber By Immobilized Cellulase

Posted on:2021-02-07Degree:MasterType:Thesis
Country:ChinaCandidate:X F TianFull Text:PDF
GTID:2370330605958797Subject:Biological engineering
Abstract/Summary:PDF Full Text Request
Use the wood fiber,a renewable carbon source widely available on the earth,to produce bioethanol instead of traditional fossil fuels can not only reduce air pollution,but also provide energy for humans in a sustainable manner.In the production process of bioethanol,the enzymatic saccharification of lignocellulose using cellulase is an important link in the production of bioethanol.However,the current dilemma of cellulase cost is too high,which seriously restricts the industrialization of bioethanol.This subject uses magnetic Fe3O4@SiO2 nanoparticles as a carrier to immobilize cellulase,and optimizes the process of enzymatic hydrolysis of lignocellulose by immobilized cellulase,which can not only improve the stability of cellulase,but also achieve the purpose of repeated recycling,with good application prospects.The main research results are as follows:1.Using modified chemical co-precipitation method to prepare Fe3O4 magnetic nanoparticles,using sol-gel method,using Fe3O4 nanoparticles as the core to prepare magnetic Fe3O4@SiO2 nanoparticle carrier,using scanning electron microscope,zeta potentiometer and hysteresis loop The experimental instrument analyzes the structure,morphology and magnetic properties of the nanoparticles.The experiments show that the prepared magnetic Fe3O4@SiO2 nanoparticles are spherical,with uniform particle size and large specific surface area.The particle size distribution is between 10nm and 100nm,the specific surface area is large,the magnetic response effect is excellent,and the dispersibility is also very good.The Fe3O4@SiO2 magnetic composite carrier can be combined with cellulase after surface amination.The study compares the carriers prepared by Fe3O4 and TEOS at different ratios,and the magnetic Fe3O4@SiO2 nanoparticles are prepared under the conditions of Fe3O4:TEOS(m:m)of 2:1,1:1,1:2,1:3 The particle carrier found that when Fe3O4:TEOS(m:m)is 1:2,its immobilized enzyme activity is the highest,reaching 652.23u/g.2.The experiment optimized the conditions of the cellulase immobilization reaction.Taking the immobilization reaction time,the immobilization reaction temperature and the initial cellulase solution concentration as experimental variables,a single factor experiment was designed to study the above three factors for immobilization Cellulase enzyme activity and enzyme activity recovery rate play a role,and on the basis of a single factor experiment carried out three factors and three levels of orthogonal experiments,the most suitable experimental conditions for cellulase immobilization are:input The free enzyme concentration was 0.2%,the immobilization temperature was 20?,and the immobilization time was 3 hours.The enzyme activity of the immobilized enzyme was the highest,reaching 531u/g,and the enzyme activity recovery rate was 88.53%.3.The conditions of enzymatic hydrolysis of poplar fiber by immobilized cellulase were optimized,and the amount of enzyme,enzymatic hydrolysis temperature and enzymatic hydrolysis pH were used as experimental variables,and the above three factors were studied by single factor experiment The effect of enzymatic saccharification rate of fiber.Experiments show that when the amount of enzyme added reaches 33u/g,the amount of enzyme has reached saturation,and the enzymatic saccharification rate is 37.53%.The enzymolysis temperature of 50? is the optimal temperature for the enzymatic hydrolysis of immobilized cellulase.At this time,the enzymolysis saccharification rate of immobilized cellulase reached 40.78%The pH value of 4 is the best environment for the enzymatic hydrolysis of immobilized cellulase,and the enzymolysis saccharification rate of immobilized cellulase reaches 40.79%.
Keywords/Search Tags:Cellulase, magnetic nanomaterials, immobilized enzyme, poplar, enzymatic hydrolysis
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