Studies On Phase Equilibria And Theoretical Calculations Of Related Subsystem In Quinary System Na⁺,K⁺,Mg²⁺,Ca²⁺//Br^--H₂O At 348 K

Studies on Phase Equilibria and Theoretical Calculations of related Subsystem in Quinary System Na+,K+,Mg2+,Ca2+//Br--H2 O at 348 K were determined with the method of isothermal solution saturation. Phase Equilibria of the following system: quinary system Na+,K+,Mg2+,Ca2+//Br--H2 O, its four quaternary subsystems NaBr-KBr-MgBr2-H2 O, NaBr-KBr-CaBr2-H2 O, KBr-MgBr2-CaBr2-H2 O, NaBrMgBr2-CaBr2-H2 O and NaBr-KBr-SrBr2-H2 O, and five ternary subsystems KBr-MgBr2-H2 O, NaBr-MgBr2-H2 O,KBr-CaBr2-H2 O, NaBr-CaBr2-H2 O, MgBr2-CaBr2-H2 O at 348 K; The solubilities and densities of above systems were mensurated at 348 K. On the basis of the experimental determination of the equilibrium solubility of data and the corresponding equilibrium solid phase, the isothermal equilibria phase diagram of the quinary system Na+,K+,Mg2+,Ca2+//Br--H2O(saturated with KBr) at 348 K, sodium content diagrams and water content diagrams of the quinary system were plotted, the Isothermal equilibria phase diagrams and water content diagrams of the quaternary systems were finished, the isothermal equilibria phase diagrams and composition-density diagrams of the ternary systems were drawn, and Comparison of solubilities calculated values with experiment values. And the solubility for part of the ternary systems and quaternary systems using Pitzer equation has made the theoretical calculation.The experimental results show that the isothermal phase diagram of the ternary system KBr-MgBr2-H2 O at 348 K contained complex salt, the complex salt is KBr?MgBr2?6H2O. The solubility diagram of the ternary system KBr-MgBr2-H2 O have two invariant points, three stable solubility isotherm curves and three crystallization fields corresponding to KBr, KBr?MgBr2?6H2O and MgBr2?6H2O. The eqibrium solid phase of the invariant points are KBr?MgBr2?6H2O+MgBr2?6H2O and KBr?MgBr2?6H2O+KBr. MgBr2 has a strong salting-out effect on KBr.The isothermal phase diagram of the ternary system NaBr-MgBr2-H2 O at 348 K is a simple saturation, neither complex salt nor solid solution. The isothermal phase diagram consists of one invariant point, two unvariant curves and two fields of crystallization. The eqibrium solid phase of the invariant point is MgBr2?6H2O+NaBr. The eqibrium solid phase of the three fields of crystallization are NaBr and MgBr2?6H2O. MgBr2 has a strong salting-out effect on NaBr.The ternary system KBr-CaBr2-H2 O at 348 K is a simple saturation, neither complex salt nor solid solution. The isothermal phase diagram consists of one invariant point, two unvariant curves and two fields of crystallization. The eqibrium solid phase of the invariant point is CaBr2?2H2O+KBr. The eqibrium solid phase of the three fields of crystallization are KBr and CaBr2?2H2O. CaBr2 has a strong salting-out effect on KBr.The ternary system Na Br-CaBr2-H2 O at 348 K is a simple saturation, neither complex salt nor solid solution. The isothermal phase diagram consists of one invariant point, two unvariant curves and two fields of crystallization. The eqibrium solid phase of the invariant point is CaBr2?2H2O+NaBr. The eqibrium solid phase of the three fields of crystallization are NaBr and CaBr2?2H2O. CaBr2 has a strong salting-out effect on NaBr.The ternary system Ca Br2-MgBr2-H2 O at 348 K contained complex salt, the complex salt is 2CaBr2?MgBr2?12H2O. The isothermal phase diagram consists of two invariant points, three unvariant solubilities curves and three crystalline regions. The eqibrium solid phase of the invariant points are 2CaBr2?MgBr2?12H2O+MgBr2?6H2O and CaBr2?2H2O+2CaBr2?MgBr2?12H2O. The eqibrium solid phase of the three fields of crystallization are CaBr2?2H2O, 2CaBr2?MgBr2?12H2O and MgBr2?6H2O. CaBr2 has salting-out effect on MgBr2.The isothermal phase diagram of the quaternary system NaBr-KBr-MgBr2-H2 O at 348 K contained complex salt, the complex salt is KBr?MgBr2?6H2O. The isothermal phase diagram consists of five unvariant curves and four fields of crystallization and two invariant points. The eqibrium solid phase of the invariant points are MgBr2?6H2O+KBr?MgBr2?6H2O and KBr+KBr?MgBr2?6H2O. The eqibrium solid phase of the four fields of crystallization are KBr, KBr?MgBr2?6H2O, NaBr and MgBr2?6H2O. MgBr2 has a strong salting-out effect on KBr.The quaternary system NaBr-KBr-CaBr2-H2 O at 348 K is a simple saturation, neither complex salt nor solid solution. The isothermal phase diagram consists of three unvariant curves, one invariant point and three fields of crystallization. The eqibrium solid phase of the invariant point is KBr+NaBr+CaBr2?2H2O. The eqibrium solid phase of the three fields of crystallization are NaBr, K Br and CaBr2?2H2O. CaBr2 has a strong salting-out effect on NaBr and KBr.The isothermal phase diagram of the quaternary system NaBr-MgBr2-CaBr2-H2 O at 348 K contained complex salt, the complex salt is 2CaBr2?MgBr2?12H2O. The isothermal phase diagram consists of five unvariant curves, four fields of crystallization and two invariant points. The eqibrium solid phase of the invariant points are NaBr+MgBr2?6H2O+2CaBr2?MgBr2?12H2O and 2CaBr2?MgBr2?12H2O+ NaBr+CaBr2?2H2O. The eqibrium solid phase of the four fields of crystallization are NaBr, CaBr2?2H2O, 2CaBr2?MgBr2?12H2O and MgBr2?6H2O.The quaternary system KBr-MgBr2-CaBr2-H2 O at 348 K has complex salt, the complex salt are 2Ca Br2?MgBr2?12H2O and KBr?MgBr2?6H2O. The isothermal phase diagram consists of three invariant points, seven unvariant curves and five fields of crystallization. The equilibrium solid phase of the invariant points are KBr+ MgBr2?6H2O+KBr?MgBr2?6H2O, MgBr2?6H2O+KBr+2CaBr2?MgBr2?12H2O and KBr+2CaBr2?MgBr2?12H2O+CaBr2?2H2O. The eqibrium solid phase of the four fields of crystallization are KBr, CaBr2?2H2O, 2CaBr2?MgBr2?12H2O, MgBr2?6H2O and KBr?MgBr2?6H2O. CaBr2 has a strong salting-out effect on K Br and MgBr2?6H2O.The isothermal phase diagram of the quaternary system NaBr-KBr-SrBr2-H2 O at 348 K is a simple saturation, neither complex salt nor solid solution. The isothermal phase diagram consists of one invariant point, three fields of crystallization and three unvariant curves. The eqibrium solid phase of the invariant point is KBr+Na Br+ SrBr2?6H2O. The eqibrium solid phase of the three fields of crystallization are NaBr, KBr and SrBr2?6H2O. SrBr2 has a strong salting-out effect on NaBr and KBr.As the experimental results show, the quinary system Na+,K+,Mg2+,Ca2+// Br--H2 O at 348 K, the double salt 2CaBr2?MgBr2?12H2O is formed. The phase diagram comprises five univariant curves, two invariant points, and four fields of crystallization(saturated with KBr): Ca Br2?2H2O, 2CaBr2?MgBr2?12H2O, NaBr and MgBr2?6H2O.