Thermodynamic study of the K---Mg---Al---Cl---SO4---H2O system at the temperature 298.15 K

The Pitzer ion-interaction model has been used for thermodynamic simulation of the binary AlCl3---H2O, Al2(SO4)3---H2O, ternary KCl---AlCl3---H2O, K2SO4---Al2(SO4)3---H2O, MgCl2---AlCl3---H2O, MgSO4---Al2(SO4)3---H2O, and the quaternary KCl---MgCl2---AlCl3---H2O systems at T=298.15 K. The optimum values of the binary parameters of ionic interactions for aluminum solutions have been calculated using activity data up to saturation of solutions. The ternary parameters have been chosen on the basis of the compositions of saturated ternary solutions taking into account the unsymmetrical mixing terms. Good agreement between experimentally determined and calculated solubilities has been found. Important thermodynamic characteristics (thermodynamic solubility product, standard molar Gibbs energy of formation) of the solid phases (simple and double salts) crystallizing in the systems under consideration are determined.