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New two-stage pretreatment for the fractionation of lignocellulosic components using hydrothermal pretreatment followed by imidazole delignification: Focus on the polysaccharide valorization

Toscan, Andréia, Fontana, Roselei Claudete, Andreaus, Jürgen, Camassola, Marli, Lukasik, Rafal Marcin, Dillon, Aldo José Pinheiro
Bioresource technology 2019 v.285 pp. 121346
Cenchrus purpureus, Penicillium, cellulose, delignification, enzymatic hydrolysis, fractionation, glucooligosaccharides, glucose, hemicellulose, imidazoles, lignocellulose, pentoses, value-added products
The combination of hydrothermal pretreatment followed by delignification with imidazole was evaluated for the first time as a potential selective two-stage fractionation for elephant grass, aiming at obtaining pure fractions susceptible to conversion to high value-added products. In addition, the recovery of cellulose and hemicelluloses and enzymatic hydrolysis yield of pretreated elephant grass were evaluated. Hydrothermal pretreatment at 180 °C under non-isothermal conditions allowed obtaining a liquor rich mainly in xylo- and glucooligosaccharides, as well as pentoses. Subsequent treatment of the recovered solid fraction with imidazole at 140 °C for 182.5 min resulted in 83.8 wt% delignification and cellulose enrichment of 97.7 wt%. The solids obtained from the two-stage pretreatment process also permitted high glucan to glucose conversion through enzymatic hydrolysis using Cellic CTec2 (99.0 mol%) or an enzymatic complex of Penicillium echinulatum (96.3 mol%).