Solubility and partition coefficient of p-toluic acid in p-xylene and water

The solubility and partition coefficient of p-toluic acid in p-xylene and water at ambient pressure were measured over the temperature range of 303.2–353.2 K. The measured solubility data and partition coefficient data were well correlated by the NRTL equation. The well-documented p-toluic acid–water system was used to validate the reliability of the sampling and analytical techniques employed. The results showed that the solubility of p-toluic acid in p-xylene and water increases with the temperature increase. The partition coefficient of p-toluic acid between p-xylene and water increases with the increasing initial mass of p-toluic acid, but decreases with the rising temperature. The equilibrium data of the ternary system are essential for the extraction process design and scale-up in the PTA wastewater recovery and treatment.

► The solubility data of p-toluic acid in p-xylene and water were measured.
► The partition coefficient of p-toluic acid between p-xylene and water was measured.
► The p-toluic acid–p-xylene–water ternary phase equilibrium model was obtained by experimental data regression.
► The model can be used to design new non-dispersive solvent extraction processes recovering p-toluic acid from wastewater.