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.