The liquid-liquid and vapor-liquid phase behavior of mixed solvent systems meaningfully changes in the presence of a non-volatile solute.[1] This issue appears as the soluting-out or soluting-in phenomena and is profitably used in distillation and solvent extraction. The butanol-water mixed solvent systems have significant importance as a reaction media or extractant in a wide variety of chemical processes and the manufacturing of cosmetics, pharmaceuticals, and essential oils.[2,3] In this respect, there is a well-sustained interest in studying the soluting effects of various additives on mixed solvents composed of 1-butanol and water. In continuation of the previous works,[4,5] herein, we have studied the soluting effects of several organic and inorganic ammonium salts on the liquid-liquid phase diagram (cloud points diagram) of aqueous 1-butanol solutions. The impacts of cation alkyl chain length, anion type, and concentration of ammonium salts on the clouding phase behavior have been discussed. The main driving force of phase separation in the investigated systems has been determined by correlating the obtained results with the relevant thermodynamic functions.
