Thermodynamic Analysis of the Solubility of Propylparaben in Acetonitrile–Water Cosolvent Mixtures

Parabens are substances used in the food, pharmaceutical and cosmetic industries. Recent studies have indicated that these substances have toxic potential, cause endocrine disruption and can easily bioaccumulate; therefore, their physicochemical properties are of industrial, biological and environmental interest. Due to their potential use in the development of more efficient and cleaner processes, the design of environmental recovery strategies and more reasonable designs for solubility in cosolvent mixtures, studies of thermodynamic analysis and mathematical modeling are of great interest. This research studies the solubility of propylparaben in acetonitrile + water cosolvent mixtures at nine temperatures by UV/Vis spectrophotometry, analyzing the solid phase by differential scanning calorimetry to evaluate possible polymorphic changes. The solubility of propylparaben is an endothermic process, where phase separation occurs at intermediate mixtures, reaching its minimum solubility in pure water at 278.15 K and the maximum solubility in pure acetonitrile at 315.15 K. The experimental data are well-correlated with the va not Hoff, Apelblat and Buchowski–Ksiazaczak models. The results revealed that possible microheterogeneity of the MeCN + W mixture can generate phase separation in intermediate mixtures, possibly due to the formation of solvates or hydrates.