Phase behavior of water-menthol based deep eutectic solvent-dodecane system

Abstract In the current work, two menthol-based hydrophobic deep eutectic solvents (DESs) have been synthesized to extract dodecane from water-dodecane emulsion at 298 K and atmospheric pressure. The equilibrium mixture produces two biphasic liquid-liquid equilibrium systems and one triphasic liquid-liquid-liquid equilibrium system. 1H NMR has been used to calculate the molar composition of each phase. For both the lauric and decanoic acid-based DES, the extract phase of biphasic region-1 is rich in DES; whereas the raffinate phase is predominantly water. However, for the biphasic region-2, the extract phase is the dodecane rich phase and raffinate phase is the mixture of DES and dodecane having a dominant composition of DES. In case of triphasic region, i.e. top phase consists of dodecane and the bottom phase is only water. The middle phase becomes an emulsion where DES is the dominant component. The selectivity analysis in the triphasic region proves that both the DESs have high selectivity to extract dodecane from the water-dodecane microemulsion. The experimental mole fractions are correlated with genetic algorithm (GA) promoted NRTL and UNIQUAC models to predict the phase behavior. An average overall root means square deviation (RMSD, %) of 0.174% is observed for the biphasic region and 0.048% for the triphasic employing GA-NRTL model. GA-UNIQUAC predicts an average overall RMSD of 0.340% for biphasic regions and 0.129% for the triphasic region.