Solubility and Data Correlation of Isoniazid in Different Pure and Binary Mixed Solvent Systems from 283.15 K to 323.15 K

The solubility of isoniazid (INH) in eight pure solvents (water, methanol, ethanol, n -propanol, isopropyl alcohol, DMF, ethyl acetate, and acetonitrile) and three binary solvent mixtures of methanol–water, ethanol–water, and isopropyl alcohol–water were experimentally determined by gravimetric method at temperatures ranging from (283.15 to 323.15) K. Expectedly, the solubility displays temperature dependence, and the most remarkable change was found in water. In all three binary solvent mixtures, INH solubility bears a maximum at 0.2–0.4 mole fraction of alcohols, and the maximum solubility values were found varying with temperature. The experimental solubility data were well correlated by the modified Apelblat, van’t Hoff, CNIBS/R–K, and Apel–JA equations. Among these models, the modified Apelblat model produces the best fitting results.