Integrated sugarcane biorefinery for first- and second-generation bioethanol production using imidazole pretreatment

Abstract

Sugarcane bagasse (SB) is a potential source for second-generation bioethanol production. Imidazole appears as a cheap green solvent that has demonstrated high efficiency in lignocellulosic biomass delignification. The main objective of this work was the use of imidazole-pretreated SB aiming the integration of first and second-generation bioethanol production in sugarcane mills’ plant. Optimized conditions (160 °C for 1 h) were applied in imidazole-pretreatment of SB. The results showed significant cellulose enrichment (167.3%) and decrease of amorphous compounds (lignin and hemicellulose), leading to a 100% conversion of glucan to glucose after enzymatic hydrolysis. Bioethanol production reached 10.4 g.L−1 at 12 h by S. cerevisiae and 11.7 g.L−1 after 30 h by P. stipitis, which represents a bioconversion yield of 77.6% and 91.5%, respectively. The imidazole-pretreatment of SB is a promising way to integrate the production of first and second-generation bioethanol, improving in 37% the total bioethanol production and reaching 110.3 L of bioethanol per ton of sugarcane. Imidazole showed great perspective for biofuel production, leading to an efficient process for waste valorization, increase of bioethanol productivities in sugarcane biorefineries.