Measurement and Correlation of the Solubility of Kaempferol Monohydrate in Pure and Binary Solvents

The solubility of kaempferol monohydrate (KFM) in five mono-solvents (ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol) and three binary solvents (ethanol + water, 1-propanol + water, 2-propanol + water) was measured by gravimetric method from 283.15 K to 323.15 K at the pressure of 0.1 MPa. It is concluded that solubility of KFM is a function of temperature and solvent composition. Statistical method was used to analyze the impact of physicochemical parameters of solvents on solubility of KFM, indicating that comprehensive factors, such as the hydrogen bonding donor capacity and cohesive energy density would influence on solubility of KFM. In addition, the COSMO-RS model was used to explore the effects of solvent-solute interactions on solubility of KFM. Further, the solubility data was correlated by the modified Apelblat equation, λh equation, and van't Hoff equation, in which the modified Apelblat equation showed the best correlation result. In the final, the apparent thermodynamic properties ( Δ sol H 0 , Δ sol G 0 , Δ sol S 0 ) of KFM were derived through the van't Hoff equation, demonstrating the dissolution process of KFM in the selected solvents was endothermic. We hope the solubility of KFM determined in this work provides data can support for its further purification.