Vapor–liquid equilibrium of polyethylene glycol monooleyl ether with 2-butanol, tert-butanol, or 1-pentanol

• Vapor–liquid equilibrium data have been measured by employing an autoclave apparatus.
• The investigated systems are PEGMOE with 2-butanol, tert-butanol, or 1-pentanol.
• The phase equilibrium data were correlated with UNIQUAC-HOC and NRTL-HOC models.
• The excess Gibbs free energies of the mixtures have been calculated.

The vapor pressures of polyethylene glycol monooleyl ether (PEGMOE) were measured at temperatures from 427.9 K to 437.3 K and the vapor–liquid equilibrium (VLE) data (p − T − xi) were also determined experimentally for three binary systems of PEGMOE + 2-butanol, PEGMOE + tert-butanol, and PEGMOE + 1-pentanol from (319.5 to 437.1) K. Four different compositions, ranging from 0.100 to 0.400 of PEGMOE in mole fraction, were investigated for each binary system. The NRTL-HOC and the UNIQUAC-HOC models were applied to correlate the experimental VLE data. Both the models obtained comparable results. The UNIQUAC-HOC model was further used to calculate the vapor composition, activity, and activity coefficients of the constituent components. The excess Gibbs free energies (GE) of the liquid mixtures were then estimated indicating that the values of GE are positive at temperatures lower than 340 K and become negative at higher temperatures.