Investigation of Phase Equilibria in Quinary Water–Salt Systems

Abstract

Isothermal methods of investigation of quinary systems and advantages of use of the translation method for investigation of quinary water–salt systems were discussed. Two quinary systems—Li, Na, K//CO3, B4O7–H2O and Na, K//Br, SO4, B4O7–H2O—were investigated by means of the translation method at 15 and 25 °C, respectively. The comparison showed a good agreement between our results and the available literature data. There are 4 points, 13 curves, and 15 fields saturated with 4, 3, and 2 different equilibrium solid phases, respectively, in Li, Na, K//CO3, B4O7–H2O systems at 15 °C. The quinary Na, K//Br, SO4, B4O7–H2O system at 25 °C involves 5 invariant points, 16 monovariant curves, and 18 divariant fields saturated with 4, 3, and 2 different equilibrium solid phases, respectively. The total phase equilibria diagrams of both of the quinary systems were constructed on the basis of obtained data. The obtained diagrams were fragmented into divariant cocrystallization fields saturated with two different equilibrium solid phases. The trivariant crystallization volumes, which reflect the structures of Jänecke dry-salt phase diagrams of the systems saturated with the relevant phases, were also extracted.