Choline Chloride Urea Effect on Liquid-Liquid Equilibria of 5-Hydroxymethylfurfural-Water-Organic Solvent Systems in the Absence and Presence of Sodium Chloride

Deep eutectic solvent (DES) has demonstrated its ability to improve the yield and selectivity in the 5-hydroxymethylfurfural (HMF) production process. Liquid-liquid extraction is a beneficial process in HMF production to recover HMF from the reaction medium. In the present study, the effect of DES (choline chloride urea) on the liquid-liquid equilibria (LLE) of HMF-water-organic solvent (methyl isobutyl ketone (MIBK) or 2-pentanol) systems in the absence and presence of sodium chloride (NaCl) was investigated at 313.15 K and atmospheric pressure (0.1 MPa). The tie-lines of the multicomponent systems were measured using several analytical methods. According to the experimental results, the extraction performance decreased with an increase in DES concentration. However, the addition of 10 wt % NaCl into the HMF aqueous DES solution can induce stronger liquid-liquid phase splitting, enhancing the separation factors and distribution coefficients of HMF by around 2.7 and 1.6 times, respectively. Additionally, MIBK showed better extraction performance in the presence of DES and NaCl with the separation factors 2.6 times higher than those of 2-pentanol and the HMF distribution coefficients above 1.8. The LLE of the multicomponent systems were correlated well with the nonrandom two-liquid (NRTL) model.