Mild One-Pot Lignocellulose Fractionation Based on Acid-Catalyzed Biphasic Water/Phenol System to Enhance Components' Processability

Effective fractionation and utilization of the three main components (cellulose, hemicellulose, and lignin) in lignocellulosic biomass give a significant opportunity for commercial operation of a lignocellulosic biorefinery. Herein, we proposed a one-pot method for lignocellulosic biomass (poplar) fractionation by acidic water/phenol pretreatment at mild temperature (120 degrees C). By this approach, three phases were obtained: water phase containing hemicellulose-derived sugars, phenol phase containing lignin, and cellulose-enriched solid phase. Up to 90% of original lignin was removed with over 96% original cellulose retained in the solid under the optimized conditions (3.5% acid based on biomass weight, 40% phenol content in water/phenol system, 120 degrees C, and 1 h). Additionally, 77% of original xylan was recovered from the water phase in the form of xylose, while negligible amounts of byproducts (e.g., furfural) formed due to the mild conditions. The pretreated substrate was enzymatically hydrolyzed to glucose, whose digestibility was 2-3 times higher than those obtained using ethanol and dioxane. The lignin, together with the phenol solvent without further separation, was used to prepare lignin-based phenolic foam with satisfactory mechanical and thermal insulation properties. The work highlights a mild one-pot acid-catalyzed pretreatment strategy to separate three main components of lignocellulose, with enhanced processability, so that value-added products can be made, thus providing an effective route for a lignocellulosic biorefinery.