Thermodynamic models for determination of the solid–liquid equilibrium of 2,5-thiophenedicarboxylic acid in (acetic acid + ethanol) binary solvent mixtures

• The equilibrium solubility data of 2,5-thiophenedicarboxylic acid in a binary system were measured.
• The solubility varies with the composition of the solvent and temperature.
• The measured data were regressed with modified Apelblat, CNIBS/R–K and Jouyban–Acree models.
• The thermodynamic properties of dissolution were calculated using van’t Hoff equation and Gibbs equation.
• The dissolution of 2,5-thiophenedicarboxylic acid in a binary system of ethanol and acetic acid is endothermic.

In this work, the solid–liquid equilibrium (SLE) of 2,5-thiophenedicarboxylic acid in (acetic acid + ethanol) binary solvent mixtures was explored at temperatures ranging from 283.15 K to 328.15 K under atmosphere pressure. For the temperature range investigated, the equilibrium solubility varies with the composition of the solvent and temperature. The equilibrium solubility data were then modelled using modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) model and Jouyban–Acree model. Computational results showed that the modified Apelblat equation and CNIBS/R–K model have the low MD (mean deviation). In addition, the thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated by the van’t Hoff analysis.

Mole fraction solubility (x) of 2,5-thiophenedicarboxylic acid versus temperature (T) in the binary solvent mixtures: ■, xA = 1.000; ●, xA = 0.898; ▲, xA = 0.746; ★, xA = 0.595; □, xA = 0.445; ○, xA = 0.296; △, xA = 0.148; , xA = 0.000.Figure optionsDownload as PowerPoint slide