Sequestration and retention of uranium(VI) in the presence of hydroxylapatite under dynamic geochemical conditions
Dawn M. Wellman A C , Julia N. Glovack B , Kent Parker A , Emily L. Richards A and Eric M. Pierce AA Pacific Northwest National Laboratory, Applied Geology and Geochemistry, PO Box 999, K3-62, Richland, WA 99354, USA.
B Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
C Corresponding author. Email: dawn.wellman@pnl.gov
Environmental Chemistry 5(1) 40-50 https://doi.org/10.1071/EN07060
Submitted: 5 September 2007 Accepted: 15 December 2007 Published: 22 February 2008
Environmental context. Contamination of surface and subsurface geologic media by heavy metals and radionuclides is a significant problem within the United State Department of Energy complex as a result of past nuclear operations. Numerous phosphate-based remediation strategies have been proposed to introduce hydroxylapatite directly or indirectly (i.e. through in situ precipitation) into subsurface regimes to act as an efficient sorbent for sequestration of metals and radionuclides such as uranium. Results presented here illustrate the importance of variable geochemical conditions on the mechanism of sequestration and long-term retention of uranium in the presence of hydroxylapatite.
Abstract. Numerous solid- and aqueous-phase phosphate-based technologies for remediating heavy metals and radionuclides have the common premise of sequestration by hydroxylapatite. Complexation reactions and hydrolysis generally preclude actinides from incorporation into intracrystalline sites; rather, surface sorption and precipitation are significant mechanisms for the sequestration of actinides. The effect of pH, aqueous speciation, and the availability of reactive surface sites on minerals such as hydroxylapatite have a significant impact on the mechanism and degree of sequestration and retention of variably charged contaminants such as uranium. Yet, little attention has been given to the sequestration and retention of uranium by hydroxylapatite under dynamic geochemical conditions that may be encountered during remediation activities. We present the results of an investigation evaluating the removal of uranium by hydroxylapatite in systems near equilibrium with respect to hydroxylapatite, and the effect of dynamic aqueous geochemical conditions, such as those encountered during and subsequent to remediation activities, on the retention of uranium. Results presented here support previous investigations demonstrating the efficiency of hydroxylapatite for sequestration of uranium and illustrate the importance of geochemical conditions, including changes to surface properties and aqueous speciation, on the sequestration and retention of uranium.
Additional keywords: kinetics, sorption, speciation.
Acknowledgements
The present work was supported in part by the US Department of Energy, Office of Environmental Management, EM-20 Environmental Cleanup and Acceleration, and by the Environmental Remediation Sciences Program, Office of Biological and Environmental Research grant number DE-FG02–06ER06–12, under Contract DE-AC06–76RL01830. This work was performed at Pacific Northwest National Laboratory, operated by Battelle Memorial Institute for the US Department of Energy under Contract DE-AC05–76RL01830. The assistance of E. T. Clayton in conducting ICP-MS analyses, and the assistance of R. M. Ermi for SEM-EDS analyses is greatly appreciated.
[1]
V. G. Chukhlantsev ,
S. I. Stepanov ,
Solubility of uranyl and thorium phosphates.
Russ. J. Inorg. Chem. 1956
, 1, 478.
[2]
V. I. Karpov ,
The solubility of triuranyl phosphate.
Russ. J. Inorg. Chem. 1961
, 6, 271.
[3]
A. I. Moskvin ,
A. M. Shelyakina ,
P. S. Perminov ,
Solubility product of uranyl phosphate and the composition and dissociation constants of uranyl phosphato-complexes.
Russ. J. Inorg. Chem. 1967
, 12, 1756.
[4]
J. M. Schreyer ,
C. F. Baes ,
The solubility of uranium(VI) orthophosphates in phosphoric acid solutions.
J. Am. Chem. Soc. 1954
, 76, 354.
| Crossref | GoogleScholarGoogle Scholar |
[5]
V. Vesely ,
V. Pekarek ,
M. Abbrent ,
A study on uranyl phosphates: III. Solubility products of uranyl hydrogen phosphate, uranyl orthophosphates and some alkali uranyl phosphates.
J. Inorg. Nucl. Chem. 1965
, 27, 1159.
| Crossref | GoogleScholarGoogle Scholar |
[6]
P. M. Bertsch ,
D. Hunter ,
B. S. R. Sutton ,
S. Bajt ,
M. L. Rivers ,
In situ chemical speciation of uranium in soils and sediments by micro X-ray absorption spectroscopy.
Environ. Sci. Technol. 1994
, 28, 980.
| Crossref | GoogleScholarGoogle Scholar |
[7]
E. C. Buck ,
N. R. Brown ,
N. L. Dietz ,
Contaminant uranium phases and leaching at the Fernald site in Ohio.
Environ. Sci. Technol. 1995
, 30, 81.
| Crossref | GoogleScholarGoogle Scholar |
[8]
[9]
[10]
D. E. Morris ,
P. G. Allen ,
J. M. Berg ,
C. J. Chisholm-Brause ,
S. D. Conradson ,
R. J. Donohoe ,
N. J. Hess ,
J. A. Musgrave ,
C. D. Tait ,
Speciation of uranium in Fernald soils by molecular spectroscopic methods: characterization of untreated soils.
Environ. Sci. Technol. 1996
, 30, 2322.
| Crossref | GoogleScholarGoogle Scholar |
[11]
V. C. Tidwell ,
D. E. Morris ,
J. C. Cunnane ,
S. Y. Lee ,
Characterizing soils contaminated with heavy metals: a uranium contamination case study.
Rem. J. 1996
, 6, 81.
| Crossref | GoogleScholarGoogle Scholar |
[12]
M. P. Elless ,
S. Y. Lee ,
Uranium solubility of carbonate-rich uranium-contaminated soils.
Water, Air, Soil Poll. 1998
, 107, 147.
| Crossref | GoogleScholarGoogle Scholar |
[13]
[14]
J. C. Seaman ,
J. S. Arey ,
P. M. Bertsch ,
Immobilization of nickel and other metals in contaminated sediments by hydroxylapatite addition.
J. Environ. Qual. 2001
, 30, 460.
| PubMed |
[15]
A. R. Millard ,
R. E. Hedges ,
A diffusion-adsorption model of uranium uptake by archaeological bone.
Geochim. Cosmochim. Acta 1996
, 60, 2139.
| Crossref | GoogleScholarGoogle Scholar |
[16]
J. Jeanjean ,
J. C. Rouchaud ,
L. Tran ,
M. Fedoroff ,
Sorption of uranium and other heavy metals on hydroxylapatite.
J. Radioanal. Nucl. Chem. Lett. 1995
, 201, 529.
| Crossref | GoogleScholarGoogle Scholar |
[17]
P. Thakur ,
R. C. Moore ,
G. R. Choppin ,
Sorption of U(VI) species on hydroxylapatite.
Radiochim. Acta 2005
, 93, 385.
| Crossref | GoogleScholarGoogle Scholar |
[18]
J. S. Arey ,
J. C. Seaman ,
P. M. Bertsch ,
Immobilization of uranium in contaminated sediments by hydroxylapatite addition.
Environ. Sci. Technol. 1999
, 33, 337.
| Crossref | GoogleScholarGoogle Scholar |
[19]
[20]
C. C. Fuller ,
J. R. Bargar ,
J. A. Davis ,
Molecular-scale characterization of uranium sorption by bone hydroxylapatite materials for a permeable reactive barrier demonstration.
Environ. Sci. Technol. 2003
, 37, 4642.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[21]
C. C. Fuller ,
J. R. Bargar ,
J. A. Davis ,
M. J. Piana ,
Mechanisms of uranium interactions with hydroxylapatite: implication for groundwater remediation.
Environ. Sci. Technol. 2002
, 36, 158.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[22]
[23]
H.-S. Park ,
I.-T. Kim ,
H.-Y. Kim ,
K.-S. Lee ,
S.-K. Ryu ,
J.-H. Kim ,
Application of apatite waste form for the treatment of water-soluble wastes containing radioactive elements. Part I. Investigation on the possibility.
J. Ind. Engineering 2002
, 8, 318.
[24]
[25]
[26]
[27]
[28]
[29]
J. C. Seaman ,
J. Hutchinson ,
B. P. Jackson ,
V. M. Vulava ,
In situ treatment of metals in contaminated soils using phytate.
J. Environ. Qual. 2003
, 32, 153.
| PubMed |
[30]
K. Nash ,
Stability and stoichiometry of uranyl phosphonate coordination compounds in acid aqueous solutions.
Radiochimica Acta 1993
, 61, 147.
[31]
K. Nash ,
Actinide phosphonate complexes in aqueous solutions.
J. Alloy. Comp. 1994
, 213–214, 300.
| Crossref | GoogleScholarGoogle Scholar |
[32]
[33]
[34]
[35]
K. Nash ,
M. P. Jensen ,
M. A. Schmidt ,
Actinide immobilization in the subsurface environment by in situ treatment with a hydrolytically unstable organophosphorous complexant: uranyl uptake by calcium phytate.
J. Alloy. Comp. 1998
, 271–273, 257.
| Crossref | GoogleScholarGoogle Scholar |
[36]
[37]
[38]
[39]
[40]
[41]
[42]
D. M. Wellman ,
J. P. Icenhower ,
A. T. Owen ,
Comparative analysis of soluble phosphate amendments for the remediation of heavy metal contaminants: effect on sediment hydraulic conductivity.
Environ. Chem. 2006
, 3, 219.
| Crossref | GoogleScholarGoogle Scholar |
[43]
[44]
[45]
[46]
[47]
S. Brunauer ,
P. H. Emmett ,
E. Teller ,
Adsorption of gases in multimolecular layers.
J. Am. Chem. Soc. 1938
, 60, 309.
| Crossref | GoogleScholarGoogle Scholar |
[48]
[49]
[50]
[51]
L. Wu ,
W. Forsling ,
P. W. Schindler ,
Surface complexation of calcium minerals in aqueous solution 1. Surface protonation at fluorapatite–water interfaces.
J. Colloid Interface Sci. 1991
, 147, 178.
| Crossref | GoogleScholarGoogle Scholar |
[52]
[53]
[54]
D. M. Wellman ,
K. M. Gunderson ,
J. I. Icenhower ,
S. W. Forrester ,
Dissolution kinetics of synthetic and natural meta-autunite minerals, X3-nn+[(UO2)(PO4)]2 xH2O, under acidic conditions.
Geochem. Geophy. Geosy. 2007
, 8, Q11001.
| Crossref | GoogleScholarGoogle Scholar |
[55]
D. M. Wellman ,
J. P. Icenhower ,
A. P. Gamerdinger ,
S. W. Forrester ,
Effects of pH, temperature, and aqueous organic material on the dissolution kinetics of meta-autunite minerals, (Na, Ca)2–1[(UO2)(PO4)]2 3H2O.
Am. Mineral. 2006
, 91, 143.
| Crossref | GoogleScholarGoogle Scholar |
[56]
[57]
[58]
[59]
[60]
A. Sandino ,
J. Bruno ,
The solubility of (UO2)3(PO4)2·4H2O(s) and the formation of U(VI) phosphate complexes: Their influence speciation in natural waters
Geochim. Cosmochim. Acta 1992
, 56, 4135.
| Crossref | GoogleScholarGoogle Scholar |