Thermodynamic analysis for determination of solid–liquid equilibrium of dibenzothiophene in a binary solvent of formic acid and butan-1-ol between (278.15 and 333.15) K

• The solubility increased with increasing temperature.
• The solubility decreased with the rise of the ratio of the formic acid.
• The solubility data were fitted using Apelblat equation, CNIBS/R–K and JA model.
• The Gibbs energy, enthalpy and entropy were calculated by the van't Hoff analysis.

In this paper, we focused on solubility and solution thermodynamics of dibenzothiophene. By gravimetric method, the solubility of dibenzothiophene was measured in (formic acid + butan-1-ol) binary solvent mixtures from 278.15 K to 333.15 K under atmosphere pressure. The solubility data were fitted using modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich–Kister (CNIBS/R–K) model and Jouyban–Acree model. Computational results showed that the modified Apelblat equation was superior to the other two equations. In addition, the thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated by the van't Hoff analysis. The experimental results showed that formic acid could be used as effective anti-solvents in the crystallization process.