Solubility and phase behavior of nickel oxide in aqueous sodium phosphate solutions at elevated temperatures. [NiO]
A platinum-lined, flowing autoclave facility was used to investigate the solubility/phase behavior of nickel oxide (NiO) in aqueous sodium phosphate solutions at temperatures between 290 and 560/sup 0/K. A layer of hydrous nickel oxide was concluded to exist on the nickel oxide surface at temperatures below 468/sup 0/K; only at higher temperatures did the anhydrous nickel oxide phase control the nickel ion solubility behavior. The measured solubility behavior was examined via a nickelous ion hydrolysis/complexing model, and thermodynamic functions for the hydrolysis/complexing rection equilibria were obtained from a least-squares analysis of the data. The existence of two new nickel ion complexes, Ni(OH)/sub 2/(HPO/sub 4/)/sup =/ and ni(OH)/sub 3/(H/sub 2/PO/sub 4/)/sup =/, is reported for the first time. The positive entropy change associated with the formation of Ni(OH)/sub 3/(H/sub 2/PO/sub 4/)/sup =/ leads to its dominance in alkaline phosphate solutions at elevated temperatures. 17 refs., 6 figs., 4 tabs.
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, NY (USA)
- DOE Contract Number:
- AC12-76SN00052
- OSTI ID:
- 5818578
- Report Number(s):
- KAPL-4184; ON: DE86012081
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPOUNDS
CHALCOGENIDES
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
ENTROPY
EXPERIMENTAL DATA
FREE ENTHALPY
HIGH TEMPERATURE
INFORMATION
MEDIUM TEMPERATURE
NICKEL COMPOUNDS
NICKEL OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PHASE TRANSFORMATIONS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
SODIUM COMPOUNDS
SODIUM PHOSPHATES
SOLUBILITY
SOLVENT PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS