Specifics of Phase Equilibria Studies in the NH4H2PO4-(NH4)2HPO4-(NH4)2SO4-NH4Cl-H2O at 25°C System by the Optimized Sections Method

Phase equilibria in the NH4H2PO4-(NH4)(2)HPO4-(NH4)(2)SO4-NH4Cl-H2O five-component water-salt system and in its boundary systems have been studied at 25 degrees C by an optimized sections method. The efficiency of the algorithm for predicting the compositions of eutonic solutions in the system has been shown. The methodology of experimental design and its implementation in studies of in-, mono-, di-, and invariant equilibria by the optimized sections method is described. The system under study is a simple eutonic type; its eutonic solution is saturated with the initial salt components. Monovariant equilibrium lines and salt cocrystallization surfaces have been studied. Experimental data have been used to plot the phase diagram of the system and its projection on the salt base. The boundaries of areas where one, two, three, or four salts crystallize together have been designated on the salt projection.