Study On Ultrasonic-assisted Enzymatic Hydrolysis Of Corn Stalk Based On Microwave Acid Treatment

Auxiliary pretreatment technology coupled with the technical means to improve the effect of biomass saccharification is the hotspot in recent years.To study the effects of the auxiliary pretreatment methods on the composition and structural characteristics of corn straw and the mechanism of improving the saccharification effect,and improve the synthesis of lignocellulosic raw materials Utilization efficiency is a key issue in the use of biomass.In this paper,the ultrasonic assisted hydrolysis of com stalks based on microwave-assisted dilute acid hydrolysis was carried out by using 3-D microscopy,Fourier transform infrared spectroscopy,X-ray diffraction and thermogravimetric analysis.The products were subjected to ultrasonic assisted enzymolysis,corn straw raw material and the effect of component dissolution,optimizing the microwave assisted acid hydrolysis and ultrasonic assisted enzymatic hydrolysis process parameters,which improve the effect of saccharification of corn stalks.In order to study the effect of microwave assisted acid treatment on the composition and structure of corn straw,microwave-assisted acid treatment of corn stalks was carried out.The results showed that the yield of reducing sugar was higher than that of acid treatment and microwave treatment,Microwave and sulfuric acid had reciprocal action and microwave assisted acid treatment can effectively improve the hydrolysis of corn stalks saccharification effect.The surface siliceous layer of maize straw after microwave assisted acid treatment was destroyed,the surface roughness increased,a large number of holes were generated,the fiber structure was cracked and the obvious mesh structure appeared.Cellulose supramolecular chain structure fragmentation,β-D-glycosidic bond breakage,large amount of hydroxyl group degradation,hemicellulose degradation,xylan degradation of xylose;cellulose and lignin partial degradation,cellulose degradation resistance barrier had decreased.The relative crystallinity of the cellulose increases,the complex crystal structure changes,and the surface siliceous layer was degraded.In order to obtain optimum process on microwave assisted acid treatment of corn stalk,based on the previous research,the microwave power,reaction time and acid concentration was chosen to independent variables,with crystallinity and reducing sugar as the response value design center design experiment to establish regression analysis and carry out significant test.The obtained regression model is extremely significant and does not collide.Under the conditions of microwave power of 540-900W,reaction time of 15-20min and acid concentration of 1～2%,the order of reducing sugar yield was sulfuric acid concentration>reaction time>microwave power.The optimal treatment conditions were determined by software optimization regression equation:microwave power was 900W,reaction time was 20mins and acid concentration was 2%.In this paper,ultrasonic-assisted enzymolysis of corn stalks treated by microwave-assisted acid was studied.The effects of solid-liquid ratio,enzymolysis time,enzyme dosage,ultrasonic power and ultrasonic time were analyzed by single factor experiment.The results showed that the order of the five factors on the enzymatic hydrolysis of corn straw was ultrasonic treatment time>enzymolysis time>solid-liquid ratio>ultrasonic power>enzyme dosage.The reasonable level of each factor was 1:10～1:20,the time was 60～72h,the amount of enzyme was 50U/g,the ultrasonic treatment power was 300W,and the ultrasonic treatment time was 20～30min.Enzymatic time(A),solid-liquid ratio(B)and ultrasonic treatment time(C)which were analyzed.The main factors affecting the yield of reducing sugar were determined.The results showed that the relationship between the reducing sugar yield and the three factors is closer to the quadratic polynomial model.The B2 and C2 were extremely significant,A2 was significant,and the interaction term BC was very significant,however the others were not significant.The results showed that the influencing factors were positively correlated with the yield of reducing sugar.The optimal conditions for ultrasonic assisted enzymolysis were as follows:ultrasonic treatment time 38.94min,solid-liquid ratio 1:20.57,enzymolysis time 70.04h,the model predicts the yield of reducing sugar in this condition was 375.46mg/g.After the model validation test,the relative error between the measured actual value and the predicted value is less than 1%.