Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

The influence of electrolytes on liquid-liquid equilibria (LLE) of water/1-butanol and on the partitioning of 5-hydroxymethylfurfural (HMF) between water-rich and 1-butanol-rich phases was investigated in this study. For that purpose, the LLE of the ternary systems water/1-butanol/HMF, water/1-butanol/salt, and the LLE of the quaternary system water/1-butanol/HMF/salt were measured at 298.15 K under atmospheric pressure. The investigated salts were composed of one of the anions Cl , CH3COO , NO3 and SO4 2 and either Li+ or Na+. By investigating the LLE of the system water/1-butanol/salt it was found that 1-butanol was salted-out from the aqueous phase by all salts, and the strength of the salting-out increased in the following order NO3- less than CH3COO- approx. = Cl- less than SO4 2- , independently of the cation. Based on the LLE data, the partition coefficient Kw_HMF of HMF between 1-butanol and aqueous phase was determined. Li2SO4 caused a pronounced salting-out of HMF from the aqueous phase, whereas only a moderate influence was observed for NaCl and CH3COONa. LiCl even caused a salting-in at LiCl molalities above 6 mol/kgH2O. electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT) was successfully used to model the influence of salts on the LLE water/1-butanol. Without fitting parameters to LLE data of the quaternary system water/1-butanol/HMF/salt, ePC-SAFT allowed predicting the salt influence on the partitioning of HMF in these systems in good agreement with the experimental data.