Liquid–liquid equilibria for the binary systems of propylene glycol ether + water measured by the phase volume method

• LLE data of two binary propylene glycol ether + water systems were reported.
• The phase volume method was used to determine the composition of conjugated phases.
• The lower critical solution temperatures of binary systems were estimated by critical scaling law.
• The UNIQUAC model was applied to correlate the experimental data successfully.

Liquid–liquid phase equilibrium for two binary systems: 1-propoxy-2-propanol + water and 1-(1-methyl-2-propoxyethoxy)2-propanol + water ranging from their lower critical solution temperatures to 328.15 K under atmospheric pressure were performed by using the phase volume method. The experimental data were further correlated with the UNIQUAC model by fitting the UNIQUAC interaction parameters as a function of temperature. The critical mass fraction and the lower critical solution temperature were determined by fitting the experimental data to the critical scaling law.