Solubility Estimation and Thermodynamic Modeling of Vanillin in Ecologically Friendly Monosolvents and Binary Systems

The solid–liquid equilibrium data of vanillin is estimated in ecologically friendly two monosolvents, acetonitrile and methanol, along with five binary systems, isopropanol + water, ethanol + water, ethylene glycol + water, acetonitrile + water, and methanol + water, in the temperature range of 288.15–323.15 K with varying mole fractions of binary mixtures at an atmospheric pressure of 94.47 kPa. For better comparison, solubility estimation was also carried out in pure solvents (water, isopropanol, ethanol, ethylene glycol), which are already reported in the literature, and it was found that there is very little deviation between the experimental and literature data. It was observed that methanol exhibited the highest solubility in monosolvent, followed by acetonitrile, ethylene glycol, ethanol, isopropanol, water, and its corresponding binary system. The solubility of vanillin increases with increases in temperature and mole fraction, as expected. Thermodynamic modeling was carried out using five different models, and the experimental data are in good agreement with the modified Apelblat model for most of the systems, apart from the acetonitrile + water binary system.