Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Phase Equilibrium in the Aqueous Ternary System KH2PO4 NaH2PO4 H2O at 288.15 and 318.15 K

You, Y.-K.[Yu-Kun], Tang, J.-H.[Jian-Hua], Lin, S.-Q.[Sheng-Qiang], Shen, S.[Si]
J. Chem. Eng. Data 2017, 62, 7, 1994-1999
ABSTRACT
Phase equilibrium in the system KH2PO4 NaH2PO4 H2O at 288.15 and 318.15 K was determined using methods of isothermal solution saturation and moist residues. The equilibrium phase solid was also verified by X-ray diffraction (XRD). Furthermore, the crystallization areas in the phase diagram were analyzed and discussed. In the phase diagram of the two temperatures, there is one invariant point, two single saturated liquid curves, and two crystallization fields corresponding to the single salts NaH2PO4*2H2O, KH2PO4 at 288.15K and NaH2PO4*H2O, KH2PO4 at 318.15K. The density of saturated solutions for the systems studied at 288.15 and 318.15 K was measured and calculated to test the precision of the chosen model. This research filled the blank of phase diagram in this ternary system and can be applied to the production of potassium dihydrogen phosphate process to optimize the crystallization and separation process of potassium dihydrogen phosphate.
Compounds
# Formula Name
1 H2KO4P monopotassium phosphate
2 H2O water
3 H2NaO4P sodium dihydrogen phosphate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • 2
  • 3
  • Mass fraction - 3 ; Liquid
  • Mass fraction - 1; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal of intercomponent compound 1
  • gravimetric + titration
  • 5
  • POMD
  • 1
  • 2
  • 3
  • Mass fraction - 3 ; Liquid
  • Mass fraction - 1; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal - 1
  • gravimetric + titration
  • 28
  • POMD
  • 1
  • 2
  • 3
  • Mass fraction - 3 ; Liquid
  • Mass fraction - 1; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal of intercomponent compound 2
  • gravimetric + titration
  • 9
  • POMD
  • 1
  • 2
  • 3
  • Mass density, kg/m3 ; Liquid
  • Mass fraction - 1; Liquid
  • Mass fraction - 3; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Pycnometric method
  • 40
  • POMD
  • 2
  • 3
  • Mass fraction - 3 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal of intercomponent compound 1
  • gravimetric + titration
  • 1
  • POMD
  • 2
  • 3
  • Mass fraction - 3 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal of intercomponent compound 2
  • gravimetric + titration
  • 1
  • POMD
  • 2
  • 3
  • Mass density, kg/m3 ; Liquid
  • Mass fraction - 3; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Pycnometric method
  • 2
  • POMD
  • 1
  • 2
  • Mass fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal - 1
  • gravimetric + titration
  • 2
  • POMD
  • 1
  • 2
  • Mass density, kg/m3 ; Liquid
  • Mass fraction - 1; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Pycnometric method
  • 2