Thermodynamic model for CoSO4(aq) and the related solid hydrates in the temperature range from 270 to 374 K and at atmospheric pressure

Abstract Available literature on the thermodynamic properties of binary CoSO4 – H2O system has been reviewed and used to derive a model for calculating the solution properties and phase equilibria in a thermodynamically consistent manner. The solution model is based on the Pitzer ion interaction approach and, with 10 adjustable parameters, is able reproduce the available literature data with good accuracy from 270 to 374 K. The length and exact form of temperature dependence of the model was optimised using the ”structural optimisation” scheme. Properties of the solid hydrates have been included in the model for calculation of solubilities. The model has been validated by successfully predicting metastable solubilities and solid–liquid–vapor equilibrium pressures.