A Novel Recyclable Alkaline Biphasic 2-Phenoxyethanol/Water System for Rice Straw Biorefinery under Mild Conditions

Abstract

A novel recyclable alkali-assisted biphasic pretreatment process under mild conditions with low water consumption is first developed. After conditions were optimized with the uniform design method, the biphasic 2-phenoxyethanol system presented superior delignification performance with only 6 mL of water consumption per gram of rice straw. Namely, the lignin removal reached 82.16% at 80 °C or 78.15% even at 55 °C. Then, according to the characteristics of the biphasic system, the entire solvent circulation process was constructed. The recycled 2-phenoxyethanol and washing wastewater were directly reused three times at 80 °C, giving more than 80% of lignin removal. Meanwhile, enzymatic digestibility of corresponding residues still exceeded 80% in acetate buffer, or 71% even in black liquor at 72 h. These show the possibility of constructing a biorefinery system based on an alkaline biphasic pretreatment process, with less water and energy consumption, fractionable composition, solvent recyclability, and black liquor utilization.