Measurement and Correlation of Solubility of γ‑Aminobutyric Acid in Different Binary Solvents

The solubility of γ-aminobutyric acid (GABA) in binary solvent mixtures of ethanol + methanol, 1-propanol + methanol and 2-propanol + methanol was measured over the temperature ranging from­(283.15 to 323.15 K with the gravimetric method. It is found that the solubility of GABA increases with increasing temperature, whereas it decreases with the increase of the GABA free-base mole fraction of ethanol, 1-propanol, or 2-propanol. The solubility data have been correlated with the modified Apelblat equation, the CNIBS/R-K equation, two modified versions of Jouyban-Acree models (the Van’t-JA equation and the Apel-JA equation) and NRTL model, respectively. The results show that the CNIBS/R-K equation gives the best correlation results in these three binary mixed solvents. Also, the mixing thermodynamic properties of enthalpy, entropy, and Gibbs energy change of GABA in these solvent mixtures have also been calculated and discussed.