Phase diagrams of liquid-liquid equilibria for the systems water-phosphoric acid-solvent entrainer at 313.15 and 333.15 K

Liquid-liquid equilibria data have been determined for the ternary system of water + phosphoric acid + solvent entrainer (1,4-dimethylbenzene, 1,2-dichloroethane, and n -hexane) at 313.15 and 333.15 K. Experiments were carried out at atmospheric pressure using stirred and thermo-regulated cells. The ternary phase diagrams were obtained by the experimental solubility and tie-line data. The Othmer-Tobias equation was used to correlate the tie-line compositions. The measured liquid-liquid equilibrium data were compared with the non-random two liquid activity coefficient model. Root mean square deviations between experimental and calculated compositions were considered satisfactory. It was showed that the non-random two liquid model of all ternary systems presented very good satisfactory results with root mean square deviations so that this model was highly appropriate to calculate thermodynamic properties of the ternary solutions. The liquid-liquid equilibrium thermodynamic properties of water + phosphoric acid + solvent entrainer can be used in research on the nature of mixing behavior of the ternary system for molecular models and industrial applications in concentration the phosphoric acid aqueous solution.