LAUSR

Abstract Liquid–liquid equilibrium (LLE) data for the ternary mixture of water + propanoic acid + 3-methylbutan-1-ol were determined within the temperature range (293.15 to 313.15) K and atmospheric pressure. The phase diagrams containing solubility and tie-line data show the type-1 behavior of LLE. Refractive index measurements were performed to determine the binodal curves and the tie-line compositions of the equilibrium phases. It has been found that the relative mutual solubility of propanoic acid was higher in solvent phase than aqueous phase. For evaluation of the capability of solvent for extraction of propanoic acid from aqueous solutions, distribution coefficients and separation factors were measured. The high values of separation factors confirm that 3-methylbutan-1-ol is a suitable choice for this purpose. The reliability of the experimental tie-lines was checked through the Othmer–Tobias correlation equation. The NRTL and UNIQUAC models were used to correlate the tie-line data.