ABSTRACT

The phase equilibrium of the ternary system (KH2PO4+ NaH2PO4 + H2O) at 303.15 K was investigated by a combination of the isothermal solution saturation method and the moist residues method. The solid phase formed in the equilibrium state was verified by X-ray diffraction (XRD). A phase diagram and a densities versus composition diagram were constructed on the basis of the experimental data of the solubility and densities. It was discovered that there was one invariant point (KH2PO4 + NaH2PO4*2H2O), two single saturated liquid curves, and two fields of crystallization corresponding to KH2PO4 and NaH2PO4*2H2O, with no double salt forming in this ternary system. Our research obtained new experimental data for this ternary system and gives guidance for potassium dihydrogen phosphate preparation and separation.

Compounds

#	Formula	Name
1	H2NaO4P	sodium dihydrogen phosphate
2	H2O	water
3	H2KO4P	monopotassium 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 - 1 ; Liquid	Mass fraction - 3; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	Gravimetric	5
POMD	1 2 3	Mass fraction - 1 ; Liquid	Mass fraction - 3; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 3	Gravimetric	13
POMD	1 2 3	Mass fraction - 1 ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 1 Crystal - 3	Gravimetric	1
POMD	1 2 3	Mass fraction - 3 ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 1 Crystal - 3	Gravimetric	1
POMD	1 2 3	Mass density, kg/m3 ; Liquid	Mass fraction - 3; Liquid Mass fraction - 1; Liquid	Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Pycnometric method	19

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

Phase Equilibrium for the Ternary System KH2PO4 + NaH2PO4 + H2O at 303.15 K

Shen, S.[Si], Tang, J.-h.[Jian-hua], Liu, Z.-h.[Zhong-hua], Kang, L.-q.[Li-quan], Mao, D.[Dun]

ABSTRACT