Abstract

In this work, thermodynamic properties of unsaturated solutions of (CuSO4 + PEG 2000 + H2O) system at (303.15, 313.15, 323.15 and 333.15) K were studied. The concentration range of the solutions was from 0.01 to 0.05 mass fraction of CuSO4 and from 0.15 to 0.3 mass fraction of poly(ethylene glycol) with an average molar mass of 2000 g/mol. Water activities were correlated with the modified Pitzer model, obtaining a good agreement between the experimental and correlated data. In addition, water activities predictions for the (CuSO4 + PEG 4000 + H2O) and (CuSO4 + PEG 2000 + H2O) systems were performed with the modified Pitzer and extended UNIQUAC models, respectively, showing that both thermodynamic models operate independently of the molar mass of the polymer used. The effect of the cations on the water activities of different (salt + PEG 4000) systems was evaluated, showing a close relation with the Molar Gibbs Energies of Hydration of the respective cations. The salting effect and Gibbs Energy change (Delta G) of different ternary systems showed that a salting-out effect occurs in all the studied systems. (C) 2020 Elsevier Ltd.