Thermodynamic properties of aqueous ternary system CuSO4 + PEG 4000+H2O at different temperatures

The present study has the aim to investigate the thermodynamic behaviour of the aqueous ternary system composed of CuSO4 and poly(ethylene glycol) (PEG). These compounds are known to form aqueous two-phase systems for applications in metal ions and biomolecules partitioning. To have a better understanding of these systems, water activities were determined at different temperatures (T = 303.15, 313.15, 323.15 and 333.15 K), using a vapour pressure osmometer. The results indicate that CuSO4 has a significant effect on the water activity of the system composed by salt-PEG-water. Additionally, water activities of the constituent binary systems, CuSO4 + H2O and PEG 4000 + H2O, were measured at the same temperatures of the ternary system. From these experimental measurements the vapour pressure values were determined for the systems and correlated with the extended UNIQUAC model, obtaining a good agreement between the experimental and correlated data. (C) 2018 Elsevier B.V. All rights reserved.