Measurement and correlation of the solubility of gallic acid in methanol plus water systems from (293.15 to 318.15) K

This work presents measurements of the solubility of gallic acid in (water + methanol) binary solvents from (293.15 to 318.15) K at atmospheric pressure using a thermostated reactor and UV/vis spectrophotometer analysis. The effects of binary solvents composition and temperature on the solubility were discussed. The solubility data were correlated with the modified Apelblat equation and semi-empirical Buchowski-Ksiazczak λh equation. The root-mean-square deviations (RMSDs) for modified Apelblat model were lower than those of the Buchowski-Ksiazczak model. The calculated solubilities show good agreement with the experimental data in the temperature range studied. Using the experimentally measured solubilities, the thermodynamic properties of dissolution of the gallic acid such as Gibbs energy (ΔsolGo), molar enthalpy of dissolution (ΔsolHo), and molar entropy of dissolution (ΔsolSo) were calculated. Therefore, the experimental data and model parameters would be useful for optimizing the process of purification of gallic in industry.