TY - JOUR
T1 - Uranium Release from Acidic Weathered Hanford Sediments
T2 - Single-Pass Flow-Through and Column Experiments
AU - Wang, Guohui
AU - Um, Wooyong
AU - Wang, Zheming
AU - Reinoso-Maset, Estela
AU - Washton, Nancy M.
AU - Mueller, Karl T.
AU - Perdrial, Nicolas
AU - O'Day, Peggy A.
AU - Chorover, Jon
N1 - Funding Information:
This research was funded by the U.S. Department of Energy (DOE) through the Subsurface Biogeochemical Research (SBR) program under grant no. SBR-DE-SC0006781. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. A portion of this research was supported by the Radioactive Waste Management Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP)-granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (no. 20141720100610). The Pacific Northwest National Laboratory (PNNL) is operated for the DOE by Battelle Memorial Institute under contract no. DE-AC05-76RL01830. The authors appreciate Dr. Carolyn I. Pearce for technical review and discussion and are grateful to Dr. Michele A. Conroy and Bruce Arey for the SEM, TEM, and EDS measurements. The XRD, SEM, TEM, EDS, and TRLIF analyses were performed in the Environmental Molecular Sciences Laboratory (EMSL). EMSL located at PNNL is a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/10/3
Y1 - 2017/10/3
N2 - The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford's cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4)·3H2O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K2(UO2)6O4(OH)6·7H2O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 × 10-12 mol g-1 s-1. In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacite-type) mineral with a release rate of 1.05-2.42 × 10-10 mol g-1 s-1. The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for the prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.
AB - The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford's cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4)·3H2O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K2(UO2)6O4(OH)6·7H2O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 × 10-12 mol g-1 s-1. In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacite-type) mineral with a release rate of 1.05-2.42 × 10-10 mol g-1 s-1. The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for the prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.
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U2 - 10.1021/acs.est.7b03475
DO - 10.1021/acs.est.7b03475
M3 - Article
C2 - 28884577
AN - SCOPUS:85030671609
VL - 51
SP - 11011
EP - 11019
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 19
ER -