Evaluating the biofuel potential of perennial grass, Pennisetum polystachion based on aqueous 1-ethyl, 3-methylimidazolium acetate ( [EMIM][Ac] ) pretreatment

Perennial grasses could be utilized as potential biofuel feedstocks and many of the members still remain unexplored. Pennisetum polystachion is a perennial grass which grows in marginal lands, and the present study aims to understand the plausibility of using it as a tropical bioenergy crop based on an eco-friendly pretreatment. The lignocellulosic content of P. polystachion was determined and 50% 1-ethyl, 3-methylimidazolium acetate ( [EMIM][Ac] ) pretreatment resulted in delignification rate comparable to pure [EMIM][Ac] in whole biomass. Glucan and xylan digestibility improved to 31.5–59.2% and 52.8–85.5%, respectively, after pretreatment. Glucan yield and total fermentable sugar recovery increased to 48.2–53.8% and 49.4–82.0%, respectively, in the treated sample. Extensive removal of cell wall–bound ferulic acid (62.5–81.7%) and p-coumaric acid (79.5–93.8%) was also observed. FTIR and XRD showed a marked decrease in lignin, hemicellulose and crystalline cellulose in pretreated biomass. Morphological changes observed through FESEM showed disruption of compact biomass structure, indicating disintegration efficiency of pretreatment. Fermentation of the enzymatic hydrolysate from pretreated samples using Saccharomyces cerevisiae at 24 h yielded 73.6, 63.5, and 47.9 mg/g of ethanol in leaf, whole biomass and culm, respectively. The findings of the current study revealed that P. polystachion can be utilized as a potential feedstock for biofuel production.