Abstract: Solubility and liquid-liquid phase equilibrium data for ternary system of [water – phosphoric acid - ester (amyl acetate)] were measured and correlated at T = 318.2 K and atmospheric pressure. The solubility curve data were determined using the cloud-point titration method. A type-1 LLE phase diagram was obtained for this ternary system, where the two liquid pairs (acid + water) and (acid + amyl acetate) are totally miscible and one liquid pair (water + amyl acetate) is partially miscible. Tie lines experimental data with the use of acidimetric titration method, the Karl Fischer technique and measuring the refractive indexes were determined. The experimental distribution coefficients and separation factors were evaluated for this system. The thermodynamic models of UNIQUAC and NRTL were utilized to correlate the experimental tie line data. The reliability of the tie line data was determined by the Othmer-Tobias equation. Maximum and minimum amount of separation factor are 6.21 and 3.89 respectively. The results show separation factors confirm the ability of these solvent for extraction of phosphoric acid from water.
