Thermodynamic analysis and molecular dynamic simulation of the solubility of saccharin in three binary solvent mixtures

The equilibrium solubility of saccharin in binary solvent mixtures of methanol + acetonitrile, ethanol + acetonitrile, and isopropanol + acetonitrile was determined by using a gravimetric method within the temperature range from 293.15 K to 323.15 K at atmospheric pressure. Intriguingly, the solubility exhibits a maximum value at around 0.5 mol fraction of alcohols in all the solvent systems regardless of temperature. The cooperation effect between the solute-solvent interaction and solvent-solvent interaction was revealed by the molecular simulation study to give the explanation for the dissolving ability of saccharin in solvent mixtures. Moreover, the experimental solubility data was correlated by the Jouyban-Acree model, van't Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model, and the Jouyban-Acree model provides the best fitting performance. Furthermore, the dissolution thermodynamic properties of apparent standard dissolution enthalpy, Gibbs free energy and entropy were computed, and the results indicate that the dissolution process of saccharin is non-spontaneous, endothermic and entropy-driven. (C) 2019 Elsevier Ltd.