Wheat Straw Hydrolytic Pretreatment Using Maleic Acid to Enhance Ethanol Production from Sugars

Abstract

In this work, the acid hydrolysis of wheat straw was studied using a batch reactor. The hydrolysis was catalyzed by 0.01-0.09 M maleic acid for 0-50 min at 140-180 ^oC. The kinetics of the hydrolysis of cellulose and hemicelluloses were simulated by a new model. This model incorporates the acidity of the liquid phase as affected by the acids produced within the complex network of reactions and by the neutralization due to the wheat straw ash content. Moreover, the pH and the temperature profile during the process was incorporated using a new modified severity factor R₀*. The model parameters were calculated using non-linear regression analysis. Process parameters investigated herein include variation in reaction temperature profile, maleic acid concentration and reaction initial and ending pH. The optimum reaction conditions resulting to maximum sugars yield were estimated according to the proposed simulation model. For log R₀*=1.971 (0.05 M maleic acid, 180 ^oC, 25 min) up to 18.2% w/w total glucose on cellulose basis, 91.0% w/w total xylose on xylan basis and 44.4% w/w total sugars on polysaccharides basis were obtained. The monosaccharides and oligosaccharides produced can be fermented to bioethanol or used for the production of high added value biobased chemicals.