Phase diagrams and thermochemical modeling of salt lake brine systems. II. NaCl+H2O, KCl+H2O, MgCl2+H2O and CaCl2+H2O systems

This study is part of a series of studies on the development of a multi-temperature thermodynamically consistent model for salt lake brine systems. Under the comprehensive thermodynamic framework proposed in our previous study, the thermodynamic properties of the binary systems (i.e., NaCl+H2O, KCl+H2O, MgCl2+H2O and CaCl2+H2O) are simulated by the Pitzer-Simonson-Clegg (PSC) model. Various thermodynamic properties (i.e., water activity, osmotic coefficient, mean ionic activity coefficient, enthalpy of dilution and solution, relative apparent molar enthalpy, heat capacity of aqueous phase and solid phases) are collected and fitted to the model equations. The thermodynamic properties of these systems are reproduced or predicted by the obtained model parameters. Comparison to the experimental or model values in the literature suggests that the model parameters determined in this study can describe all of the thermodynamic and phase equilibria properties over wide temperature and concentration ranges. This modeling study of binary systems provides a solid basis for property predictions of salt lake brines under complicated conditions.