Browsing by Author "Da Silva, Roberto"
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Item Enhancing the production of the fermentable sugars from sugarcane straw: A new approach to applying alkaline and ozonolysis pretreatments(Elsevier Ltd, 2020-09-21) Orduña Ortega, Julieth; Mora Vargas, Jorge Andrés; Metzker, Gustavo; Gomes, Eleni De Barros; Da Silva, Roberto; Boscolo, MaurícioThe present study, sugarcane straw residue (SCS) was submitted to a combination of mild alkaline pretreatment and ozone cycles in a rotary reactor aiming to obtain fermentable sugars. The SCS exposed to short ozone cycles and short reaction times proved to be as efficient as long ozone exposure times usually employed, with no significant variation on the concentration of the fermentable sugars. Also, studies carried out on the ozone concentration, ozone exposure time, reaction time and biomass amount on the ozonolysis process were conducted. The washing processes after alkaline pretreatment and ozonolysis were also studied. During the alkaline pretreatment, approximately 73% of total phenolic compounds (TPC) was generated. After the first wash 79% of the TPC was washed away and 95% was removed after the second wash. The TPC content in wash solution obtained after ozonolysis is about 2.3% of the TPC generated with the alkaline pretreatment. For the enzymatic hydrolysate 0.20 g L−1 of TPC was obtained, a low value compared to similar studies. The inhibitor detected in the highest concentration was acetic acid for all solutions, except for ozonolysis where fumaric acid predominated. Hydroxymethylfurfural (HMF) and furfural were detected in amounts of less than 10 mg L−1.Item Soaking and ozonolysis pretreatment of sugarcane straw for the production of fermentable sugars(Elsevier B.V., 2019-11-28) Orduña Ortega, Julieth; Mora Vargas, Jorge Andrés; Perrone, Olavo Micali; Metzker, Gustavo; Gomes, Eleni De Barros; Da Silva, Roberto; Boscolo, MaurícioIn 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%).