Thermodynamic properties of aqueous poly(ethylene glycol) 2000-Na2MoO4 systems

In this work, the thermodynamic behavior of aqueous solutions containing the solutes Na2MoO4 and poly(ethylene glycol) (PEG) was investigated. These chemistries are vital components for forming the aqueous two-phase system constituted by the three compounds. In this sense, the water activity of the ternary system at 303.15, 313.15, 323.15 and 333.15 K were determined, using vapor pressure osmometry. During the measurements, the concentration of PEG was fixed to 0.30, 0.25, 0.20, 0.10 and 0.05 mass fraction whereas the salt concentration was fixed to 0.14, 0.12, 0.10, 0.08, 0.06, 0.04 and 0.02 mass fraction. The results show that sodium molybdate has a significant effect on the water activity in the PEG-salt-water system. From these measurements, values of the vapor pressure of solutions were determined. Finally, the investigated systems were modeled with the UNIQUAC model which allowed correlating the properties of these multi-solute aqueous solutions.