(Solid + liquid) phase equilibrium for the ternary system (NaCl + NaH2PO4 + H2O) at T = (298.15 and 313.15) K and atmospheric pressure

Abstract

The (solid+liquid) phase equilibrium and physico-chemical properties of the ternary system (NaCl+NaH2PO4+H2O) at T=(298.15 and 313.15)K have been studied by the method of isothermal solution saturation. The solid phases formed in the systems studied were determined by the Schreinemaker wet residue method. The phase diagrams and the diagrams of physico-chemical properties versus composition in the system at T=(298.15 and 313.15)K were constructed based on the measured data. In the phase diagrams, there were in all one invariant point, two univariant curves, and two crystallization regions corresponding to NaH2PO4·2H2O, NaCl. Physico-chemical properties (viscosity, density, refractive index and pH values) in the equilibrium solution changed regularly with increasing NaH2PO4 concentration. The (solid+liquid) phase equilibria and physico-chemical properties can be used for the solvent extraction process of NaH2PO4 in the industrial production and further theoretical studies.