Chromium (III) Hydroxide Solubility in the Aqueous Na⁺-OH⁻- H₂PO⁻₄- HPO²⁻₄-PO³⁻₄-H₂O System: A Thermodynamic Model

Journal Article · Sat Oct 30 04:00:00 EDT 2004 · Journal of Solution Chemistry, 33(10):1213-1242

DOI:https://doi.org/10.1007/s10953-004-7137-z· OSTI ID:15020719

Rai, Dhanpat; Moore, Dean A; Hess, Nancy J; Rao, Linfeng; Clark, Sue B

Chromium(III)-phosphate reactions are expected to be important in managing high-level radioactive wastes stored in tanks at many DOE sites. Extensive studies on the solubility of amorphous Cr(III) solids in a wide range of pH (2.8 to 14) and phosphate concentrations (10⁻⁴ to 1.0 m) at room temperature (22±2)°C were carried out to obtain reliable thermodynamic data for important Cr(III)-phosphate reactions. A combination of techniques (XRD, XANES, EXAFS, Raman spectroscopy, total chemical composition, and thermodynamic analyses of solubility data) was used to characterize solid and aqueous species. Contrary to the data recently reported in the literature⁽¹⁾, only a limited number of aqueous species [Cr(OH)₃H₂PO-₄, Cr(OH)₃ (H₂PO₄)²⁻₂), and Cr(OH)₃HPO²⁻₄] with up to about four orders of magnitude lower values for the formation constants of these species are required to explain Cr(III)-phosphate reactions in a wide range of pH and phosphate concentrations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15020719
• Report Number(s): PNNL-SA-40904; KP1302000
• Journal Information: Journal of Solution Chemistry, 33(10):1213-1242, Journal Name: Journal of Solution Chemistry, 33(10):1213-1242 Journal Issue: 10 Vol. 33
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CHEMICAL COMPOSITION
CHROMIUM
Cr(III)-phosphate complexes
Cr(OH)3(H2PO4)22-
Cr(OH)3(am)
Cr(OH)3H2PO4-
Cr(OH)3HPO42-.
HIGH-LEVEL RADIOACTIVE WASTES
HYDROXIDES
PHOSPHATES
RAMAN SPECTROSCOPY
SOLUBILITY
TANKS
THERMODYNAMIC MODEL
THERMODYNAMICS
Thermodynamics
X-RAY DIFFRACTION
hydrolysis constants
ion-interaction parameters
solubility