Measurement and Modeling of Solubility of <i>para</i>-<i>tert</i>-Butylbenzoic Acid in Pure and Mixed Organic Solvents at Different Temperatures

Abstract

The solid–liquid phase equilibrium of para - tert -butylbenzoic acid in methanol, ethanol acetic acid, propan-2-ol, hexane, toluene, 1-octanol, para - tert -butyltoluene, methyl 4- tert -butylbenzoate, and binary (methanol + methyl 4- tert -butylbenzoate) mixed solvent have been determined experimentally within the temperature range of 293.15–333.15 K at atmospheric pressure using a static equilibrium method. The solubility of para - tert -butylbenzoic acid increased with the increase in temperature for the pure solvents, while in the case of methanol + methyl 4- tert -butylbenzoate a maximum solubility effect is achieved at 0.6115 solute-free mole fraction of methanol. The experimental solubility data in pure and binary solvent system were correlated by the modified Apelbat equation, the λ h (Buchowski) equation, and the NRTL model, among which the modified Apelbat equation provided better agreement than those with the other models. Furthermore, to understand the nature of interactions involved in a solute–solvent system, the dissolution thermodynamic properties, including enthalpy, entropy, and Gibbs free energy, were determined. This experimental data will be an aid for the design and optimization of the separation and purification processes involving para - tert -butylbenzoic acid.