Second Generation Bioethanol Production from Soybean Hulls Pretreated with Imidazole as a New Solvent

Soybean hulls (SH) are the main industrial waste from soybean processing, representing 5-8% of the whole grain. Imidazole was employed for the hydrothermal pretreatment of SH and further bioethanol production. Different pretreatment temperatures (120 and 180 degrees C) and times (1 and 3 h) were tested. Lignin removal and glucose yield were significantly influenced by temperature. After 48 h of enzymatic hydrolysis of imidazole-treated SH (120 degrees C, 1 h), 32.7 g/L of glucose and 9.4 g/L of xylose were obtained. A maximum bioethanol yield of 78.9% was reached after 12 h of fermentation by Saccharomyces cerevisiae using SH enzymatic hydrolysate. Imidazole appears to be a potential alternative to pretreat lignocellulosic wastes such as SH for the production of second-generation biofuels and other biomolecules.

Automated summary

Soybean hulls, which make up 5-8% of the whole grain, are the primary industrial waste from soybean processing. Imidazole was used to hydrothermally pretreat soybean hulls and produce bioethanol. Different pretreatment temperatures and times were tested, and lignin removal and glucose yield were affected by temperature. Enzymatic hydrolysis of imidazole-treated soybean hulls resulted in significant glucose and xylose yields. Fermentation of the enzymatic hydrolysate by Saccharomyces cerevisiae achieved a high bioethanol yield. Imidazole shows potential as an alternative pretreatment method for lignocellulosic wastes like soybean hulls to produce second-generation biofuels and other biomolecules.