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Title: Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate

Abstract

Phosphate addition to subsurface environments contaminated with uranium can be used as an in situ remediation approach. Batch experiments were conducted to evaluate the dependence of the extent and mechanism of uranium uptake on the pathway for reaction with calcium phosphates. At pH 4.0 and 6.0 uranium uptake occurred via autunite (Ca(UO2)(PO4)3) precipitation irrespective of the starting forms of calcium and phosphate. At pH 7.5, the uptake mechanism depended on the nature of the calcium and phosphate. When dissolved uranium, calcium, and phosphate were added simultaneously, uranium was structurally incorporated into a newly formed amorphous calcium phosphate solid. Adsorption was the dominant removal mechanism for uranium contacted with pre-formed amorphous calcium phosphate solids,. When U(VI) was added to a suspension containing amorphous calcium phosphate solids as well as dissolved calcium and phosphate, then removal occurred through precipitation (57±4 %) of autunite and adsorption (43±4 %) onto calcium phosphate. The solid phase speciation of the uranium was determined using X-ray absorption spectroscopy and laser induced fluorescence spectroscopy. Dissolved uranium, calcium, and phosphate concentrations with saturation index calculations helped identify removal mechanisms and determine thermodynamically favorable solid phases.

Authors:
 [1];  [2];  [3];  [2];  [1]
  1. Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
  2. Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States
  3. Department of Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1245508
Alternate Identifier(s):
OSTI ID: 1337248
Report Number(s):
PNNL-SA-115276
Journal ID: ISSN 0013-936X
Grant/Contract Number:  
AC05-76RL01830; SC0006857; ECS-0335765; AC02-06CH11357
Resource Type:
Published Article
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Name: Environmental Science and Technology Journal Volume: 50 Journal Issue: 6; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Environmental Molecular Sciences Laboratory; Calcium phosphate; Calcium; Uranium; Phosphates; Precipitation

Citation Formats

Mehta, Vrajesh S., Maillot, Fabien, Wang, Zheming, Catalano, Jeffrey G., and Giammar, Daniel E. Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate. United States: N. p., 2016. Web. doi:10.1021/acs.est.5b06212.
Mehta, Vrajesh S., Maillot, Fabien, Wang, Zheming, Catalano, Jeffrey G., & Giammar, Daniel E. Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate. United States. doi:10.1021/acs.est.5b06212.
Mehta, Vrajesh S., Maillot, Fabien, Wang, Zheming, Catalano, Jeffrey G., and Giammar, Daniel E. Mon . "Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate". United States. doi:10.1021/acs.est.5b06212.
@article{osti_1245508,
title = {Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate},
author = {Mehta, Vrajesh S. and Maillot, Fabien and Wang, Zheming and Catalano, Jeffrey G. and Giammar, Daniel E.},
abstractNote = {Phosphate addition to subsurface environments contaminated with uranium can be used as an in situ remediation approach. Batch experiments were conducted to evaluate the dependence of the extent and mechanism of uranium uptake on the pathway for reaction with calcium phosphates. At pH 4.0 and 6.0 uranium uptake occurred via autunite (Ca(UO2)(PO4)3) precipitation irrespective of the starting forms of calcium and phosphate. At pH 7.5, the uptake mechanism depended on the nature of the calcium and phosphate. When dissolved uranium, calcium, and phosphate were added simultaneously, uranium was structurally incorporated into a newly formed amorphous calcium phosphate solid. Adsorption was the dominant removal mechanism for uranium contacted with pre-formed amorphous calcium phosphate solids,. When U(VI) was added to a suspension containing amorphous calcium phosphate solids as well as dissolved calcium and phosphate, then removal occurred through precipitation (57±4 %) of autunite and adsorption (43±4 %) onto calcium phosphate. The solid phase speciation of the uranium was determined using X-ray absorption spectroscopy and laser induced fluorescence spectroscopy. Dissolved uranium, calcium, and phosphate concentrations with saturation index calculations helped identify removal mechanisms and determine thermodynamically favorable solid phases.},
doi = {10.1021/acs.est.5b06212},
journal = {Environmental Science and Technology},
number = 6,
volume = 50,
place = {United States},
year = {2016},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acs.est.5b06212

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Cited by: 11 works
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Works referencing / citing this record:

Comparative analysis of uranium bioassociation with halophilic bacteria and archaea
journal, January 2018