Experimental determination and modelling of the solubilities of sodium sulfate and potassium sulfate in sub- and supercritical water

In this work, the solubility data of 20 different inorganic compounds were correlated by 7 available empirical and semi-empirical models in literature. The division criteria of four influential factors (temperature, pressure, the range of solubility data and the number of data points) were established to evaluate the correlative capability and applicability of these models at different conditions. Also, a novel four-parameter semi-empirical model has been proposed. Furthermore, the solubilities of sodium sulfate and potassium sulfate in sub- and supercritical water were measured at temperatures and pressures ranging from 633.15 to 723.15 K and 18–26 MPa, respectively. The experimental data were correlated using the reported models and the proposed novel model. The obtained results indicated that Cp-model is the best to fit the solubilities of these sulfates. In addition, the proposed model also exhibits a good correlation performance for the salt's solubility behaviors.