Multiphase equilibria for mixtures containing acetic acid, water, propylene glycol monomethyl ether, and propylene glycol methyl ether acetate

A static-type apparatus equipped with a visual cell was utilized in the present study to measure isothermal vapor-liquid equilibrium (VLE) and vapor-liquid-liquid equilibrium (VLLE) data over a temperature range of 323.24 to 393.15 K. The VLE data were determined experimentally for binary mixtures of propylene glycol rnonomethyl ether (PGME) + propylene glycol methyl ether acetate (PGMEA) and acetic acid + PGME. A minimum pressure azeotrope exhibits on each isotherm of acetic acid + PGME. The VLLE data were also measured for water + PGMEA and water + PGMEA + PGME. The VLLE data could be correlated well by the NRTL and the UNIQUAC models accompanied with the Hayden-O'Connell (HOC) correlation for water + PGMEA over a wide temperature range as linearly temperature-dependent parameters were adopted. The NRTL-HOC model, together with the parameters determined from the phase-equilibrium data of the constituent binaries, predicted reasonably well the binodal curves of water + PGMEA + PGME. By adjustment of six parameters simultaneously, the NRTL-HOC and the UNIQUAC-HOC models correlated satisfactorily the ternary VLLE properties of water + PGMEA + PGME.