Ternary phase diagrams for aqueous mixtures of butyric acid with several solvents: Experimental and correlated data

• LLE data of (water + butyric acid + solvent) were determined.
• LLE data were measured at 298.15, and atmospheric pressure.
• Experimental tie-line data was tested by Othmer–Tobias method.
• Tie-line data were compared with data obtained from UNIFAC and UNIQUAC.
• Distribution coefficients were evaluated for the immiscibility region.

Octan-1-ol, acetophenone, ethyl butanoate (ethyl butyrate), ethyl pentanoate (ethyl valerate), and 1,3-diethyl propanedioate (diethyl malonate) were used as solvents for determining the ternary liquid phase diagrams of aqueous mixtures consisting butyric acid, with the intention of bringing more effective and environmental friendly solvents into use. The liquid–liquid equilibrium (LLE) data for water + butyric acid + solvent ternary systems were investigated at 298.15 K and atmospheric pressure. The ternary phase diagrams composed of solubility data and tie-lines were presented graphically. The reliability of the experimental tie-lines was tested by Othmer–Tobias correlation. The experimental tie-line data were compared with the results correlated by means of UNIQUAC model, and predicted by the UNIFAC method. It is concluded that the used solvents may be adequate extractants to extract butyric acid from its dilute aqueous solutions.