Solubility of gallic acid, vanillin, syringic acid, and protocatechuic acid in aqueous sulfate solutions from (293.15 to 318.15) K

Abstract

The solubility of gallic acid, vanillin, syringic acid, and protocatechuic acid in aqueous solutions of various concentrations of sodium sulfate was determined from (293.15 to 318.15) K at atmospheric pressure using a thermostatted reactor and HPLC analysis. Results showed a salting-out effect on the solubility of the tested phenolic compounds. The solubility data were accurately correlated to a semiempirical equation. The temperature dependence of the solubility data were used to estimate thermodynamic properties such as Gibbs free energy (ΔsolGo), molar enthalpy of dissolution (ΔsolGo), and molar entropy of dissolution (ΔsolGo). © 2008 American Chemical Society.