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Title: The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH 3 gas

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1396608
Grant/Contract Number:
EM0000598; AC05-76RL01830
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Geochemistry
Additional Journal Information:
Journal Volume: 73; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 10:07:49; Journal ID: ISSN 0883-2927
Publisher:
Elsevier
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Katsenovich, Yelena P., Cardona, Claudia, Lapierre, Robert, Szecsody, Jim, and Lagos, Leonel E. The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH 3 gas. United Kingdom: N. p., 2016. Web. doi:10.1016/j.apgeochem.2016.08.002.
Katsenovich, Yelena P., Cardona, Claudia, Lapierre, Robert, Szecsody, Jim, & Lagos, Leonel E. The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH 3 gas. United Kingdom. doi:10.1016/j.apgeochem.2016.08.002.
Katsenovich, Yelena P., Cardona, Claudia, Lapierre, Robert, Szecsody, Jim, and Lagos, Leonel E. 2016. "The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH 3 gas". United Kingdom. doi:10.1016/j.apgeochem.2016.08.002.
@article{osti_1396608,
title = {The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH 3 gas},
author = {Katsenovich, Yelena P. and Cardona, Claudia and Lapierre, Robert and Szecsody, Jim and Lagos, Leonel E.},
abstractNote = {},
doi = {10.1016/j.apgeochem.2016.08.002},
journal = {Applied Geochemistry},
number = C,
volume = 73,
place = {United Kingdom},
year = 2016,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.apgeochem.2016.08.002

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  • Remediation of uranium in the deep unsaturated zone is a challenging task, especially in the presence of oxygenated, high-carbonate alkalinity soil and pore water composition typical for arid and semi-arid environments of the western regions of the U.S. This study evaluates the effect of various pore water constituencies on changes of uranium concentrations in alkaline conditions, created in the presence of reactive gases such as NH3 to effectively mitigate uranium contamination in the vadose zone sediments. This contaminant is a potential source for groundwater pollution through slow infiltration of soluble and highly mobile uranium species towards the water table. Themore » objective of this research was to evaluate uranium sequestration efficiencies in the alkaline synthetic pore water solutions prepared in a broad range of Si, Al, and bicarbonate concentrations typically present in field systems of the western U.S. regions and identify solid uranium-bearing phases that result from ammonia gas treatment. In previous studies (Szecsody et al. 2012; Zhong et al. 2015), although uranium mobility was greatly decreased, solid phases could not be identified at the low uranium concentrations in field-contaminated sediments. The chemical composition of the synthetic pore water used in the experiments varied for silica (5–250 mM), Al3+ (2.8 or 5 mM), HCO3- (0–100 mM) and U(VI) (0.0021–0.0084 mM) in the solution mixture. Experiment results suggested that solutions with Si concentrations higher than 50 mM exhibited greater removal efficiencies of U(VI). Solutions with higher concentrations of bicarbonate also exhibited greater removal efficiencies for Si, Al, and U(VI). Overall, the silica polymerization reaction leading to the formation of Si gel correlated with the removal of U(VI), Si, and Al from the solution. If no Si polymerization was observed, there was no U removal from the supernatant solution. Speciation modeling indicated that the dominant uranium species in the presence of bicarbonate were anionic uranyl carbonate complexes (UO2(CO3)2-2 and UO2(CO3)3-4) and in the absence of bicarbonate in the solution, U(VI) major species appeared as uranyl-hydroxide (UO2(OH)3- and UO2(OH)4-2) species. The model also predicted the formation of uranium solid phases. Uranyl carbonates as rutherfordine [UO2CO3], cejkaite [Na4(UO2)(CO3)3] and hydrated uranyl silicate phases as Na-boltwoodite [Na(UO2)(SiO4)·1.5H2O] were anticipated for most of the synthetic pore water compositions amended from medium (2.9 mM) to high (100 mM) bicarbonate concentrations.« less
  • The impacts of the El Niño–Southern Oscillation (ENSO) events on shortwave and longwave cloud radiative effects (CRESW and CRELW) and the underlying changes in cloud fraction as well as aerosol emissions, wet scavenging and transport are quantified using three 150-year simulations in preindustrial conditions by the CESM model. Compared to recent observations from Clouds and the Earth’s Radiant Energy System (CERES), the model simulation successfully reproduced larger variations of CRESW over the tropical western and central Pacific, Indonesian regions, and the eastern Pacific Ocean, as well as large variations of CRELW located mainly within the tropics. The ENSO cycle ismore » found to dominate interannual variations of cloud radiative effects, especially over the tropics. Relative to those during La Niña events, simulated cooling (warming) effects from CRESW (CRELW) during El Niño events are stronger over the tropical western and central Pacific Ocean, with the largest difference exceeding 40 Wm–2 (30 Wm–2), with weaker effects of 10–30 Wm–2 over Indonesian regions and the subtropical Pacific Ocean. Sensitivity tests show that variations of cloud radiative effects are mainly driven by ENSO-related changes in cloud fraction. The variations in medium and high cloud fractions each account for about 20–50% of the interannual variations of CRESW over the tropics and almost all of the variations of CRELW between 60°S and 60°N. The variation of low cloud fraction contributes most interannual variations of CRESW over the mid-latitude oceans. Variations in natural aerosol concentrations considering emissions, wet scavenging and transport explained 10–30% of the interannual variations of both CRESW and CRELW over the tropical Pacific, Indonesian regions and the tropical Indian Ocean. Changes in wet scavenging of natural aerosol modulate the variations of cloud radiative effects. Because of increased (decreased) precipitation over the tropical western Pacific Ocean in El Niño (La Niña) events, increased (decreased) wet scavenging of natural aerosols dampens more than 4–6% of variations of cloud radiative effects averaged over the tropics. In contrast, increased surface winds cause feedbacks that increase sea spray emissions that enhance the variations by 3–4% averaged over the tropics.« less
  • The C/sup 13/ isotope effect for isotopy at the methyl carbon atom was measured in the cyanization of methyl iodide in water solution between 11.4 and 58.0 deg . As a check on these results and those previously reported for isotope fractionation at the cyanide carbon atom, experiments were carried out also in which the reagents were present at equal concentrations instead of one being in large excess; the check experiments yield data of considerably higher quality than either set obtained under high-concentration-ratio conditions. There is general agreement among the three sets of results, but it is not sufficiently closemore » to permit detailed speculations concerning the nature of the reaction coordinate motion in terms of simple models. The methyl carbon isotope effect in the cyanization is much larger than that observed in the related hydrolysis, a fact which cannot be explained unless account is taken of the details of activation changes in C -H bonding. (auth)« less
  • The superconducting properties and the phase and chemical composition of Bi[sub x]Pb[sub 0.3]Sb[sub 0.1]Sr[sub y]Ca[sub 2]Cu[sub 3]O[sub z] (x = 1.5, 1.6, and 1.7; y = 1.9, 2.0, and 2.1) material synthesized by one-step and multistep thermal treatments have been investigated. The multistep annealing between 825-875[degree]C promotes the 2223 phase. The change of Bi concentration has little effect on the 2223 phase formation, regardless of the kind of thermal treatment used, but increasing the Sr concentration (y > 2) strongly inhibits this phase. It has also been established that the loss of Pb after synthesis depends on the initial Bimore » concentration. The loss of Pb decreases when the initial Bi content is lower. 19 refs., 8 figs., 1 tab.« less