Understanding triethylammonium hydrogen sulfate ([TEA][HSO<inf>4</inf>]) pretreatment induced changes in Pennisetum polystachion cell wall matrix and its implications on biofuel yield

11 páginas, 3 tablas, 9 figurasBiofuel potential of a widely grown perennial grass, Pennisetum polystachion, was analyzed using triethylammonium hydrogen sulfate ([TEA][HSO4]) pretreatment. The optimum pretreatment condition was selected based on the delignification efficiency. 80% [TEA][HSO4] at 140 °C for 45 min at 10% sample load, yielding high delignification rate (65.8%) was selected as the optimum pretreatment condition. Recycling of [TEA][HSO4] showed up to 90% IL recovery and significant delignification rates. Glucan yield in the biomass increased to 67.8%, whereas digestibility of biomass enhanced from 16.7% to 84.1%. Extensive deferuloylation (88%) and decoumarylation (86.4%) were observed in the sample following pretreatment. Diferulic acids were not detected in pretreated samples indicating their complete removal. HMF (0.1 mg/mL) and furfural (0.001 mg/mL) produced during pretreatment were very low compared to conventional methods. FTIR and XRD confirmed pronounced delignification and hemicellulose dissolution, and FESEM showed a marked difference in the surface morphology, including defibrillation and enhanced porosity. An ethanol yield of 275 mg/g biomass (84.7% of theoretical maxima) was achieved using Saccharomyces cerevisiae MTCC 36 after 15 h of fermentation. The results obtained from the current study can shed light on utilizing P. polystachion as a potential biofuel feedstock using a low-cost ionic liquid [TEA][HSO4].The present study did not receive any specific grants from public, commercial or not-for-profit agencies.Peer reviewe

Pretreatment of sugarcane postharvest leaves by γ-valerolactone/water/FeCl<inf>3</inf> system for enhanced glucan and bioethanol production

12 páginas, 4 tablas, 7 figurasThe potential of sugarcane postharvest leaves for fermentable sugar yield and bioethanol production was analyzed using FeCl3 catalyzed γ-valerolactone/water pretreatment in the present study. Widely cultivated Indian cane variety Co 86032 (Nayana) was selected for the analysis. Cellulose (52.7 ± 5%), hemicellulose (33.9 ± 3.5%) and lignin (18 ± 0.3%) were estimated in postharvest leaves. Optimized GVL/water/FeCl3 pretreatment (70% GVL/300 mM FeCl3 in 30% water at 120 °C for 3 h) resulted in high delignification (74%) and hemicellulose dissolution (85.6%). Extensive removal of ester-linked ferulic acid (94.2%) and p-coumaric acid (84.4%) was also observed after pretreatment. The pretreatment-induced changes were visualized through FESEM, FTIR, XRD and confocal imaging. Only trace amounts of furfural and HMF were detected in the pretreated slurry. At 96 h of saccharification, 82.5% glucose was yielded. Fermentation of enzymatic hydrolyzate using S. cerevisiae MTCC-36 resulted in ethanol yield of 0.434 g/g glucose at 21 h. Current study revealed that, FeCl3 catalyzed GVL/water pretreatment causes effective deconstruction of cane leaves for bioethanol production.The present study did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.Peer reviewe