Experimental Investigation and Thermodynamic Modeling in Liquid-Liquid Equilibrium of Water + Propionic Acid + Cyclic Alcohols at T= 303.2, 313.2, and 323.2 K

Propionic acid extraction is of economic and environmental importance. In the present study, the liquid-liquid equilibrium data of the ternary system of water + propionic acid + cyclic alcohols (cyclopentanol and cyclohexanol) was obtained at 303.2, 313.2, and 323.2 K temperatures. Phase behavior of type-1 has been observed for studied systems. 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 coefficients of the inter-molecular interaction have been determined. RMSD values for NRTL and UNIQUAC models in cyclopentanol-containing systems were 0.0107 and 0.0057, respectively, and 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 indicates the ability of the solvents to extract propionic acid.