Thermodynamic studies of solvent extractions systems-IV. The binary mixtures of tris-2-ethyl hexyl phosphate with benzene, carbon tetrachloride, hexane and chloroform

From the total pressures, measured between 25 and 45°C, by the isoteniscope method, the excess thermodynamic functions were evaluated in the tris-2-ethyl hexyl phosphate (TEHP)-C₆H₆, C₆H₁₄, CCl₄ and CHCl₃ systems. In all cases, negative deviations from Raoult's were observed and the excess free energies of mixing were almost independent of temperature in solutions rich in TEHP (mole fraction of a diluent less than half). Athermal-thermal effects are important for more dilute mixtures. Results in the TEHP-CHCl₃ system, in the 25-45°C range, can be interpreted as due to the formation of AB and AB₂ complexes (A-TEHP, B-CHCl₃) with equilibrium constants K₁ = 9.70 and K₂ = 55.8.