Zwitterionic liquid vs. ionic liquid analogue biomass pretreatment ability

Abstract

One-pot ethanol production, which involves successive biomass pretreatments, enzymatic hydrolysis, and fermentation in a single vessel, is essential for practical bioethanol production. To achieve this, low-toxicity pretreatment solvents such as a zwitterionic liquid, OE₂imC₃C, are necessary. Although the cellulose-dissolving ability of OE₂imC₃C has been studied, its biomass pretreatment ability has not been thoroughly investigated. Herein, we investigated the biomass pretreatment ability of OE₂imC₃C at various temperatures and concentrations. The mildest conditions for successful pretreatment were 75 wt% OE₂imC₃C at 90 °C. On the other hand, OE₂imC₃C exhibited a lower pretreatment ability than [C₂mim]OAc, which is the best-known cellulose-dissolving ionic liquid. The main reason for the low pretreatment ability of OE₂imC₃C was its high viscosity. Reducing their viscosity is a key factor for designing zwitterionic liquids with high pretreatment ability.