Optimization of Ionic Liquid Pretreatment of Mixed Softwood by Response Surface Methodology and Reutilization of Ionic Liquid from Hydrolysate

We investigated the feasibility of producing bioethanol from mixed softwood pretreated with the ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim]Ac). The optimal pretreatment conditions were determined by response surface methodology to be 100A degrees C for 15 h, and the fermentable sugar yield was estimated to be 92.5%. Efficient pretreatment of softwood was maintained even after reutilizing [Bmim]Ac up to four times. Through the enzymatic saccharification and subsequent fermentation, bioethanol was produced with 0.42 g/g of yield and 0.24 g/L/h of productivity, which clearly suggests that efficient and economical bioethanol production can be achieved by optimizing pretreatment processes and reutilizing ionic liquid.