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

Abstract

The ternary system of K 2 SO 4 + KH 2 PO 4 + H 2 O 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 K 2 SO 4 + KH 2 PO 4 + H 2 O 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.

Stable (solid+liquid) phase equilibrium for the ternary systems (K2SO4+KH2PO4+H2O), (K2SO4+KCl+H2O) at T=313.15K

“…endpoints and most solubilities data reported in reference [10] are systematically lower when compared with the values of Bel'teschev, F.V. et al…”

“…[9] had reported phase equilibrium data at T = (273.15, 293.15, 303.15) K for the ternary system (K 2 SO 4 + KH 2 PO 4 + H 2 O) by the method of visual polythermic. Furthermore, and Pan Wang [10] had investigated this ternary system at T = (298.15 and 333.15) K by the method of isothermal solution saturation and moist residues. The quality of the measured data may be investigated by comparing it with literature values.…”

“…[9] was the earliest to report (K 2 SO 4 + KH 2 PO 4 + H 2 O) phase equilibrium data at T = (273. 15, 293.15, 303.15) K. Furthermore, Pan Wang [10] had investigated the ternary system of (K 2 SO 4 + KH 2 PO 4 + H 2 O) at T = (298. 15 and 333.15) K by the method of isothermal solution saturation and moist residues.…”

Phase Equilibrium for the System KH2PO4 – K2SO4 – H2O at 25°С

“…3 представлены ре-зультаты исследования системы [4,7]. Данные по растворимости в области кристаллизации дигидрофосфата калия [4] хорошо согласуются с полученными в работе.…”

“…Данные по растворимости в области кристаллизации дигидрофосфата калия [4] хорошо согласуются с полученными в работе. Результаты исследова-ния [7] отличаются, главным образом в области кристаллизации сульфата калия. Очевидно, что расхождения в данных по растворимости сульфата калия в присутствии дигидрофосфата калия обусловлены качеством использованных в работе солей.…”