Study On Microwave-Assisted Dilute Acid Hydrolysis Of Corncob

Due to the corn cob is rich contained in hemicellulose that can be widely used to produce xylose for production and life,so the study of hydrolyzing corn cob to produce xylo-oligosaccharides is significance.It not only makes full use of biomass resources,but also provides a reliable way for the generation of healthy new energy sources.In this study,while corn cob was adopted as raw biomass,using the response surface optimization method in the microwave dilute sulphuric acid to explore the corncob hydrolysis to produce reducing sugar.Before the study of corn cob hydrolysis had the hydrolysis of a single component in corn cob been studied.Then using orthogonal experiments to find the optimal hydrolysis efficiency.Finally,the differences between the hydrolysis of corn cob and the single component hydrolysis were compared.The main results are as follows:?1?The one was to comparison hydrolysis efficiency by three single factors.The other was to study the hemicellulose hydrolysis law and the level of each single factor.An orthogonal experiment L₉?3⁴?was applied to get the optimum conditions.The range analysis and variance analysis for the results showed that the optimal hydrolysis conditions was as follows:the hydrolysis time was 10min,the microwave power was 350W and the concentration of acid was 3%.Under these conditions,the reducing sugar yield was 93.68%.The structural changes in the before and after hemicelluloses hydrolysis were analyzed by FITR and XRD characterization,and it could be know that the hemicellulose was more easily hydrolyzed in dilute acids.?2?Studying the cellulose hydrolysis law and selecting the level of each single factor though the single factor experiment.An orthogonal experiment L₉?3⁴?was applied to get the optimum conditions.The range analysis and variance analysis for the results showed that the optimal hydrolysis conditions was as follows:the hydrolysis time was 25min,the microwave power was 350W and the concentration of acid was 7%.Under these conditions,the reducing sugar yield was 10.65%.It was found that the cellulose was poorly hydrolyzed under the experimental conditions though to analyze the cellulose hydrolysis residue with FITR and XRD analysis.?3?The appropriate range of factors have been selected in the single-factor hydrolysis test of corn cob.Then there were a response surface method to optimize corncob's hydrolysis conditions.A one-dimensional quadratic regression equation had been built according to the model fitting.The coefficient of determination R² was 0.9737 that can prove the model is reliable.The results showed that the optimal hydrolysis conditions was as follows:the hydrolysis time was 12min,the solid to liquid ratio was 9.7g/L,the microwave power was356.27W and the concentration of acid was 3.55%.Under these conditions,the reducing sugar yield was 29.17%.The actual experiment to hydrolysis yield was 28.87%with the best value of the difference does not exceed 5%.Though the Saeman model to fit the corncob hydrolysis kinetics could find that sugars accumulate faster and then the formation and degradation of post-reducing sugar reach a balance.The paper detected the hydrolysate by HPLC that found the hydrolysate sugar mainly were xylose and glucose.?4?Comparison of corncob hydrolysis and single component hydrolysis could know that the actual yield of corncobs is lower than the theoretical value of single components.The mutual mosaic structure of cellulose and hemicellulose in corn cob affects the hydrolysis of hemicellulose.If the hemicellulose in the corn cob is separated,the yield of hemicellulose hydrolysis can be improved.