Deep eutectic solvent-based microextraction system for simultaneous lignocellulose fractionation and furfural production

Abstract

A biomass conversion process with a microextraction system was developed for simultaneous lignocellulose fractionation and conversion. The liquid-liquid biphasic platform was composed of a deep eutectic solvent (DES) (polyethylene glycol : oxalic acid) and methyl isobutyl ketone (MIBK). Microemulsion (O/W) was formed on constant stirring and stabilized by sodium salt crystal, which also acted as an interphase catalyst to enhance furfural yields. Furfural was continuously extracted into MIBK after being formed in the DES. The highest furfural yield of 76.5% was obtained when the reaction was conducted at 150 °C for 60 min in the presence of 12.3 wt% NaCl. The extracted lignin was functionalized with polyethylene glycol, with substantial retention of the native structure of lignin. The pulp also showed high enzymatic digestibility of cellulose. This work demonstrated the role of salt crystals in stabilizing Pickering emulsions for microextraction and their function in simultaneous biomass fractionation and conversion for high-value platform chemicals, paving the way toward sustainable biorefineries.