Solubility equilibria. From data optimization to process simulation*

Models that accurately predict solid–solute phase equilibria in aqueous electrolyte solutions are of mounting importance for numerous industrial processes, especially those operating at high temperatures, pressures, and concentrations. The incorporation of such electrolyte models into process simulators is in great demand. This communication will focus on thermodynamically consistent models that can simultaneously predict densities, heat capacities, and apparent molar enthalpies of multicomponent electrolyte mixtures together with activities of their constituents. Data optimization issues to be discussed include the CALPHAD (CALculation of PHAse Diagrams) method applied to electrolyte systems and the generation of robust models that extrapolate well outside the parameterization space. Recent development of software suitable for the simulation of industrial processes involving concentrated electrolyte solutions will be outlined.