Liquid-liquid equilibria of ternary and quaternary systems involving 5hydroxymethylfurfural, water, organic solvents, and salts at 313.15K and atmospheric pressure

Effect of 1-ethyl-3-methylimidazolium tetrafluoroborate on the phase equilibria for systems containing 5-hydroxymethylfurfural, water, organic solvent 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 2pentanol) 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.

Carbohydrates are the renewable feedstocks to produce 5-hydroxymethylfurfural (HMF) through hexose dehydration. Fructose is widely applied as the raw material in the formation of HMF due to its high rate and selectivity of conversion to HMF. In the HMF production process, the liquid–liquid extraction is essentially used to extract HMF from the reaction medium. The use of an ionic liquid (IL) and a deep eutectic solvent (DES) has been recognized to increase the yield of HMF by suppressing the formation of side products. The aim of this study is to systematically study the effect of fructose on the extraction performance of HMF in the water-1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]­[BF4]) or choline chloride urea (ChCl–urea)–sodium chloride (NaCl) solution at 313.15 K and an atmospheric pressure of 0.1 MPa. Methyl isobutyl ketone was used as a selective extraction solvent. The separation factor and the distribution coefficient of HMF were obtained from liquid–liquid equilibrium (LLE) data to interpret the extraction performance. According to the results in this study, fructose had a minimal effect on the extraction performance of HMF. For the LLE system using [EMIM]­[BF4], the HMF distribution coefficient values showed comparable values to the LLE system without fructose. However, the separation factors decreased by around 1.1 times. Furthermore, fructose decreased the separation factors by around 1.3 times and distribution coefficients of HMF by around 1.1 times for the LLE system using ChCl–urea. A comparison of the IL and DES used indicated that HMF extraction from an aqueous DES (ChCl–urea) demonstrated a better extraction performance with the separation factor, and the HMF distribution coefficient values were 1.4 and 1.2 times higher than those for HMF extraction from an aqueous IL ([EMIM]­[BF4]), respectively. The experimental LLE data were correlated well using the non-random two-liquid model. The reliability of the experimental LLE data was also satisfactorily ascertained by the Hand and Othmer–Tobias correlations.