Liquid-liquid equilibria study of the (water plus phosphoric acid plus hexyl or cyclohexyl acetate) systems at T = (298.15, 308.15, and 318.15) K: Measurement and thermodynamic modelling

摘要

Liquid-liquid equilibrium (LLE) data for the (water + phosphoric acid + n-hexyl acetate or cyclohexyl acetate) ternary systems were determined at T = (298.15, 308.15 and 318.15) K and p = 101.3 kPa. The cloud point method was used to obtain the solubility and the Karl-Fischer, acidimetric titration, and refractive index methods were used to determine the tie-line values. Both the ternary systems exhibit type-1 behavior of LLE. The experimental values were regressed and acceptably correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie lines was confirmed using the Othmer-Tobias plot. Experimental distribution coefficients and separation factors were fitted using the Kamlet-Taft LSER model. The influence of temperature on the biphasic area and separation factor was found to be minor. As a result, both the esters are suitable separating agents for aqueous phosphoric acid mixtures. (C) 2016 Elsevier Ltd. All rights reserved.