Exploration of lower critical solution temperature DES in a thermoreversible aqueous two-phase system for integrating glucose conversion and 5-HMF separation

With the deepening of the research on the conversion of cellulose biomass to furfural, there is no green and efficient method to separate sugars and 5-HMF. This study utilized a thermoreversible aqueous two-phase system (ATPS) coupled with tetrabutylammonium bromide ([N 4444 ]Br)- based deep eutectic solvents (DES) and inorganic salts for separating glucose and 5-HMF. The thermal characteristics of DESs were analyzed by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The thermoreversible phase behavior of ATPS was determined by phase diagram. Furthermore, the process factors were optimized, such as the type and concentration of DES and phosphate, the temperature, and the time of ATPS were investigated, to maximize the separation of glucose and 5-HMF. Finally, the ATPS was a successful integrated catalytic reaction of glucose involving CrCl 3 and 5-HMF separation. The results showed that the ATPS consist of 30 wt% [N 4444 ]Br-EG and 25 wt% K 2 HPO 4 had the most efficient extraction rate, 5-HMF reached 96.0 ± 0.6%, and mainly existed in the DES phase, while glucose was enriched in salt phase, and the extraction rate reached 99.9 ± 0.03%. And the 5-HMF yield reached 25.6 ± 1.1% in the production separation integrated platform. This thermoreversible ATPS may provide a guide for the effective extraction of furfural from biomass-derived glucose.