Magnetite stability in aqueous sodium phosphate solutions at elevated temperatures
Magnetite (Fe[sub 3]O[sub 4]) is shown to transform to a sodium ferric hydroxy-phosphate compound in concentrated, alkaline sodium phosphate solutions at elevated temperatures via 1/3 Fe[sub 3]O[sub 4](s) + 13/3 Na[sup +] + 2 HPO[sub 4][sup =] [r reversible] Na[sub 4]Fe(OH)(PO[sub 4])[sub 2][center dot]1/3NaOH(s) + 1/3 H[sup +] + 1/6 H[sub 2](g). The thermodynamic equilibrium for this reaction was defined in the system Na[sub 2]O-P[sub 2]O[sub 5]Fe[sub 3]O[sub 4]-H[sub 2]O for Na/P molar ratios between 2.1 and 3. Quantitative chemical, infrared and Mossbauer spectroscopic, and X-ray diffraction analyses are employed to verify that the precipitated solid was a single phase having the non-whole number stoichiometric Na/P ratio 2.15 [plus minus] 0.02. Standard entropy and free energy of formation for sodium ferric hydroxyphosphate were calculated to be 729.2 J/mol-K and [minus]3550.3 kJ/mol, respectively.
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, NY (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC12-76SN00052
- OSTI ID:
- 6443144
- Report Number(s):
- KAPL-4735; CONF-930821-1; ON: DE92016359
- Resource Relation:
- Conference: 9. international symposium on environmental degradation of materials in nuclear power systems, St. Louis, MO (United States), Aug 1993
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
20 FOSSIL-FUELED POWER PLANTS
MAGNETITE
STABILITY
AQUEOUS SOLUTIONS
EQUILIBRIUM
SODIUM PHOSPHATES
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMIC PROPERTIES
ALKALI METAL COMPOUNDS
DISPERSIONS
IRON ORES
MINERALS
MIXTURES
ORES
OXIDE MINERALS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
SODIUM COMPOUNDS
SOLUTIONS
TEMPERATURE RANGE
400201* - Chemical & Physicochemical Properties
360105 - Metals & Alloys- Corrosion & Erosion
200104 - Fossil-Fueled Power Plants- Components