ABSTRACT

The solid-liquid equilibrium of the ternary system of water-phosphorus pentoxide-calcium carbonate was studied using a synthesis method based on the measurement of the solution conductivity under atmospheric air pressure. Two isotherms were established at 25 deg C and 70 deg C with control of calcium carbonate decomposition in contact with aqueous solutions of P2O5. A phase sequences study was carried out at 25 deg C in the isoplethic section of CaCO3-H2O-P2O5 system. The solid phases observed at these temperatures are: dehydrated calcium hydrogen phosphate CaHPO4.2H2O, Hydroxyapatite Ca10(PO4)6(OH)2, anhydrous calcium hydrogen phosphate CaHPO4 and calcium dihydrogen phosphate monohydrate Ca(H2PO4)2.H2O. All stable solids are characterized by X-ray diffraction and the Schreinemaker method.

Compounds

#	Formula	Name
1	O5P2	diphosphorus pentaoxide
2	H2O	water
3	CaO	calcium monoxide

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	3 1 2	Mass fraction - 3 ; Liquid	Temperature, K; Liquid Mass fraction - 1; Liquid	Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	electrical conductivity	6
POMD	3 1 2	Mass fraction - 3 ; Liquid	Temperature, K; Liquid Mass fraction - 1; Liquid	Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 2	electrical conductivity	19
POMD	3 1 2	Mass fraction - 3 ; Liquid	Temperature, K; Liquid Mass fraction - 1; Liquid	Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 3	electrical conductivity	25

Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Thermodynamic equilibrium in the system H2O+P2O5+CaCO3 at 25 and 70 deg C: Application for synthesis of calcium phosphate products based on calcium carbonate decomposition

Bakher, Z., Kaddami, M.

ABSTRACT