Recovery of propionic acid from aqueous solution is economically and environmentally important. In this study, the liquid-liquid equilibrium data of water + propionic acid + cyclic alcohols (cyclopentanol and cyclohexanol) ternary system was obtained at 303.2, 313.2, and 323.2 K temperatures. These ternary systems exhibit type-1 behavior of liquid-liquid equilibrium (LLE). The Hand and Bachman equations confirm the validity of the measured data. For correlation of liquid-liquid equilibrium data, the NRTL and UNIQUAC thermodynamic models have been used and the inter-molecular interactions coefficients have been determined. RMSD values for NRTL and UNIQUAC models in cyclopentanol containing systems were 0.0107 and 0.0057, respectively, for cyclohexanol 0.0108 and 0.0076 respectively, which showed the accuracy of these models in correlation liquid-liquid equilibrium data. The values of the selectivity factor for both solvents larger than the unit are obtained, which shows that these solvents can be used to extract propionic acid from aqueous solution.
