Soaking and ozonolysis pretreatment of sugarcane straw for the production of fermentable sugars

Abstract

In the present study, sugarcane straw residue (SCS) is used to generate fermentable sugars. Impregnation in different media and ozonolysis were combined for SCS treatment. The best results were obtained for the basic medium (80 °C at atmospheric pressure for 8 h) followed by ozonolysis (rotary reactor, ozone concentration of 0.24% (w/w), 60 min of reaction and 35% moisture content). Increasing the ozone concentration from 0.24% to 1.3% (w/w) did not increase the amount of glucose released (yields of 60.8 and 60.2%, respectively) indicating that no high ozone concentrations are required. The chemical characterization of the treated material showed that there were no losses due to holocellulose dissolution. In contrast, the cellulose and hemicellulose content increased by 75% and 42%, respectively when compared to the raw material, while the lignin content decreased by 47%. Samples subjected to ozonolysis showed the greatest reduction in the recalcitrance to enzymatic hydrolysis, reaching 60 and 71% of yield in glucose and xylose conversion, respectively, when compared to the impregned material (26 and 31% respectively) and the raw material (4 and 5%).