Solid–Liquid Phase Equilibrium for the Ternary System K₂SO₄ + KH₂PO₄ + H₂O at (298.15 and 333.15) K

Abstract

The ternary system of K2SO4 + KH2PO4 + H2O at (298.15 and 333.15) K was investigated by the method of isothermal solution saturation and moist residues. Thus the solubility data of the system were obtained, and phase diagrams of K2SO4 + KH2PO4 + H2O at (298.15 and 333.15) K were constructed on the basis of the solubility data. The solid phase in the system mentioned above was also identified. The crystallization field of potassium sulfate and potassium dihydrogen phosphate (KDP) were determined, and the crystallization field of potassium sulfate was larger than that of potassium dihydrogen phosphate. The density of saturated solutions for the systems studied at (298.15 and 333.15) K was also measured. The solubility data, density, and the phase equilibrium diagrams for the ternary system can provide the fundamental basis for the preparation of potassium dihydrogen phosphate in potassium sulfate and potassium dihydrogen phosphate aqueous mixtures.