The role of water-soluble polymers on the solubility of isophthalic acid in aqueous medium: Measurements, data correlation and thermodynamic analysis

Abstract

The mole fraction solubility of isophthalic acid (IPA) was measured in water and four water-soluble polymers including polyethylene glycol dimethyl ether 250 (PEGDME 250) and polyethylene glycols (PEGs) 200, 400 or PEG 600 at 293.15 K to 313.15 K along with determining the solubility of IPA in PEGDME 250 + water at the same range temperatures and also in PEGs 200, 400 or 600 + water at 298.15 K. The solubility measurements were made with the common shake-flask method under atmospheric pressure (≈ 85 kPa) in where the mass fraction of each polymer (wp) in binary mixtures was 0.0 to 1.0. At the same temperature and mass fraction of PEGDME 250, PEGs 200, 400 and 600, the upward trend for mole fraction solubility of IPA in binary mixtures was: PEG 600 + water > PEG 400 + water ≥ PEGDME 250 + water > PEG 200 + water. The experimental mole fractions of IPA were then validated and correlated using three versions of Jouyban-Acree model (Jouyban-Acree, Jouyban-Acree-van't Hoff and the modified Jouyban-Acree-van't Hoff), the modified Wilson and its combined version with the van't Hoff equation, NRTL and Wilson attaining the overall average percentage deviations (OARD) ≤ 12.7%. According to the lower value of OARD obtained from the back-correlated solubility data with the Jouyban-Acree model (6.4%) than the others, its ability in prediction of IPA solubility in the untested binary mixtures, i.e. wp = 0.1 to 0.9 with an interval 0.1 at 293.15 K, 303.15 K, 308.15 K and 313.15 K was tested and observed a good agreement between the predicted and experimental data. Finally, an endothermic and entropy-driven dissolution processes of IPA in PEGDME 250 + water was observed, in where it was only entropy-driven in wp ≥ 0.6 for PEG-based binary mixtures.