Han H. J.,Ma J. J.,Xing K. Q.,Shao D. X.,Zhong S. K.
Abstract In this work, the equal-water activities for the ternary system LiCl−KCl−H 2 O and its sub-binary systems LiCl−H 2 O were determined using an isopiestic method at 323.15 K. The determined isopiestic composition lines for the LiCl−KCl−H 2 O system were found to deviated Zdanovskii rule high with increasing ionic strength of the mixture solution. The addition of KCl to an aqueous solution of LiCl was found to decrease and increase the water activity at low and high LiCl molality. The Pitzer–Simonson–Clegg (PSC) model was used to represent the experimental determined water activities of the titled system and the calculated values are discussed. Based on the calculated results, the turning point appears at about 17.0 mol kg −1 LiCl solution.
Water activity for binary KCl–H2O, NaCl–H2O and MgCl2–H2O, as well as two ternary NaCl–MgCl2–H2O and KCl–MgCl2–H2O, systems has been measured by using an isopiestic method at 323.15 K. The isopiestic results obtained show that the isopiestic composition lines of the NaCl–MgCl2–H2O system was found to obey the Zdanovskii rule, whereas the KCl–MgCl2–H2O system was observed to deviate slightly. The experimental water activities determined were applied to regress the parameters of the Pitzer model with a good agreement. The model with new parameters is validated by comparing water activity predictions with those given in the literature and not used in the parametrization process and calculating the solubility of the NaCl–MgCl2–H2O and KCl–MgCl2–H2O systems at various temperatures with the comparison of literature values.