Solubilities of hydroxybenzaldehyde isomers and their mixture in subcritical 1,1,1,2-tetrafluoroethane

The static flow method coupled with gas chromatography analysis was used to measure the solubilities of pure 4-hydroxybenzaldehyde, 3-hydroxybenzaldehyde and their mixture with equal molar ratio in subcritical 1,1,1,2-tetrafluoroethane (R134a) at 308, 318, 328 K and 5.0-15.0 MPa. Comparison of the solubility of each solute in the binary subcritical R134a system with that in the ternary system was made. Furthermore, the effect of molecular structure on the solubility was discussed, and the improvement effect factor (μ) and separation factor (SF) of each solid solute in the ternary system had been investigated. In addition, the solubility enhancement factor (δ) had been defined and calculated to compare the solubility of the same solute in subcritical R134a with that in supercritical carbon dioxide. The solubility data of pure solute in the binary subcritical R134a system were correlated by Chrastil and Méndez-Santiago and Teja (MST) models, while the solubility data in the ternary system were correlated by their modified models (Chrastil-G and MST-S), Sovová and its modified models. All the calculated solubility data showed satisfactory agreements with the experimental one.