Spectrophotometric and Calorimetric Studies of U(VI) Complexation with Sulfate at 25-70oC
Journal Article
·
· Journal of Chemical Thermodynamics
OSTI ID:959416
Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the U(VI)/sulfate complexes and determine the equilibrium constants and enthalpy of complexation at 25-70 C. Results show that U(VI) forms moderately strong complexes with sulfate, i.e., UO{sub 2}SO{sub 4}(aq) and UO{sub 2}(SO{sub 4}){sub 2}{sup 2-}, in this temperature range and the complexes become stronger as the temperature is increased: 2-fold and 10-fold increases in the stability constants of UO{sub 2}SO{sub 4}(aq) and UO{sub 2}(SO{sub 4}{sub 2}{sup 2-}), respectively, when the temperature is increased from 25 C to 70 C. The complexation is endothermic and entropy-driven, showing typical characteristics of inner-sphere complexation and 'hard acid'/'hard base' interactions. The thermodynamic trends are discussed in terms of dehydration of both the cation (UO{sub 2}{sup 2+}) and the anion (SO{sub 4}{sup 2-}) as well as the effect of temperature on the structure of water.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- Chemical Sciences Division
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 959416
- Report Number(s):
- LBNL-1408E
- Journal Information:
- Journal of Chemical Thermodynamics, Journal Name: Journal of Chemical Thermodynamics; ISSN JCTDAF; ISSN 0021-9614
- Country of Publication:
- United States
- Language:
- English
Similar Records
Spectrophotometric and Calorimetric Studies of Np(V) Complexation with Sulfate at 10-70oC
Thermodynamics of neptunium(V) fluoride and sulfate at elevatedtemperatures
THERMODYNAMICS OF NEPTUNIUM(V) FLOURIDE AND SULFATE AT ELEVATED TEMPERATURES
Journal Article
·
Mon Jun 16 00:00:00 EDT 2008
· Journal of Thermal Analysis and Calorimetry
·
OSTI ID:961592
Thermodynamics of neptunium(V) fluoride and sulfate at elevatedtemperatures
Conference
·
Mon Oct 30 23:00:00 EST 2006
·
OSTI ID:919372
THERMODYNAMICS OF NEPTUNIUM(V) FLOURIDE AND SULFATE AT ELEVATED TEMPERATURES
Technical Report
·
Sun Mar 05 23:00:00 EST 2006
·
OSTI ID:886039