Measurement and Correlation of LLE Data for the Ternary System Water+Phosphoric Acid+1-Pentanol at 278.2 K and 288.2 K

In this study, experimental tie-line data analysis was conducted for the ternary system (water+phosphoric acid+1-pentanol) at 278.2 K and 288.2 K and atmospheric pressure. The compositions of equilibrium phases were determined using the acid-base and the Karl Fisher titration methods and mass balance calculations. Reliability of the experimental data was investigated using the Othmer–Tobias and Hand equations. The UNIQUAC thermodynamic model was applied for correlation of the equilibrium tie-line points. The experimental tie-lines were satisfactorily regressed using the thermodynamic model (%rmsd=2.48). Distribution coefficients and separation factors were determined over the biphasic area. Separation factors were greater than one in all the investigated feeds at the studied temperatures that guarantees the successful separation process. The Kamlet-Taft parameters were applied for the LSER modeling of the obtained distribution coefficients and separation factors. The effect of temperature on extraction process was investigated by adding a modification term in Kamlet-Taft equation. The ternary system revealed good fittings with the modified LSER model. The results showed that, the temperature decrement had positive effect on the extraction ability of the 1-pentanol for separating phosphoric acid from aqueous solution.

Keywords:

Phosphoric acid , Liquid-liquid equilibrium , Thermodynamic model , LSER approach