Enhancing the potential production of bioethanol with bamboo by γ-valerolactone/water pretreatment

Abstract

In this study, the effect of the γ-valerolactone (GVL)/H₂O pretreatment system on bamboo (Neosinocalamus affinis) for enzymatic hydrolysis and ethanol fermentation was investigated. The performance characterization of the pretreated bamboo substrates, including the chemical composition, the structural characteristics, and the ability to produce bioethanol, were evaluated. The recovered substrates were enzymatically hydrolyzed for 48 h and then fermented to bioethanol. For the cellulose in the raw bamboo material, the highest cellulose-to-glucose conversion yield (CGCY) was achieved at 140 °C for 2 h with GVL : H₂O = 8 : 2, which was 73.39%, and the cellulose-to-ethanol conversion yield (CECY) was 67.00%. This indicated that 183.5 kg of bioethanol could be produced per ton of bamboo, which was 9.71-folds higher than that directly converted from the untreated raw bamboo powder. Under these conditions, 50.60% of the active lignin can be recovered and be used as a wood-derived feedstock for further high-valued utilization. Meanwhile, the maximum concentration of fermentation inhibitors formed after pretreatment was about 140.9 mmol L⁻¹, and had weak inhibition to the subsequent reaction. It has been shown that the cellulose could be effectively separated from bamboo and converted into bioethanol through the GVL/H₂O pretreatment system.