Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Three ternary diagrams of ethyl paraben, ethanol, water and propyl paraben, ethanol, water have been determined. The liquid-liquid phase separation has been reported in these three ternary diagrams. In pure water the ethyl paraben and propyl paraben solubility are both below 1 mg/g, while in pure ethanol the solubility is more than three orders of magnitude higher. While the solution saturated with propyl is homogeneous at 30 C, and the solution saturated is homogenous at 40 C, however, the higher temperatures induces a liquid-liquid phase separation of the ethanol-water mixture, and the ternary phase diagrams contain five different regions. The size of the liquid-liquid phase separation region increases with increasing temperature. The systematic changes of thermodynamic properties between butyl paraben, propyl paraben and ethyl paraben has been investigated.