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Title: Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Subsurface Biogeochemical Research (SBR)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1154625
Resource Type:
Journal Article
Resource Relation:
Journal Name: Soil Science Society of America Journal; Journal Volume: 71; Journal Issue: 2
Country of Publication:
United States
Language:
English

Citation Formats

John M.,Phillippi, Vijay A.,Loganathan, Melissa J.,McIndoe, Mark O.,Barnett, T. Prabhakar,Clement, and Eric E.,Roden. Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate. United States: N. p., 2007. Web. doi:10.2136/sssaj2006.0159.
John M.,Phillippi, Vijay A.,Loganathan, Melissa J.,McIndoe, Mark O.,Barnett, T. Prabhakar,Clement, & Eric E.,Roden. Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate. United States. doi:10.2136/sssaj2006.0159.
John M.,Phillippi, Vijay A.,Loganathan, Melissa J.,McIndoe, Mark O.,Barnett, T. Prabhakar,Clement, and Eric E.,Roden. Mon . "Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate". United States. doi:10.2136/sssaj2006.0159.
@article{osti_1154625,
title = {Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate},
author = {John M.,Phillippi and Vijay A.,Loganathan and Melissa J.,McIndoe and Mark O.,Barnett and T. Prabhakar,Clement and Eric E.,Roden},
abstractNote = {},
doi = {10.2136/sssaj2006.0159},
journal = {Soil Science Society of America Journal},
number = 2,
volume = 71,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Raman spectra of all the actinide(V) (except protactinium (Pa)) and actinide(VI) complexes in 2 M(sodium carbonate Na/sub 2/CO/sub 3/) solutions have been obtained. A resonance Raman effect was observed for neptunium(Np)(VI), plutonium(Pu)(VI), and americium(Am)(VI) and found to be related to the position of the charge-transfer bands observed in the corresponding electronic spectra and to the formal potential of actinide(VI)/actinide(V) couples in carbonate solution. No resonance effect was observed in the Raman spectrum of uranium (U(VI)). The symmetric stretching frequency (nu/sub 1/) of the MO/sub 2//sup 2 +/ group was shifted in carbonate solutions as compared to acidic noncomplexing solutions andmore » decreased regularly with an increase in the atomic number of the actinide considered. In contrast, the nu/sub 1/ frequencies of the MO/sub 2//sup +/ group for actinide(V) species in carbonate solutions did not vary as the atomic number of the actinide increased. In comparison to the v/sub 1/ frequencies in acidic solutions, in carbonate solution a small negative shift was observed for nu/sub 1/ of Np(V) and a positive shift was obtained for nu/sub 1/ of Am(V). The Raman spectra of Na/sub 3/MO/sub 2/(CO/sub 3/)/sub 2/ solid compounds were obtained for M = Np, Pu, and Am. The nu/sub 1/ frequencies of the MO/sub 2//sup +/ ions decreased linearly with increasing atomic number of the actinide and were higher than the corresponding values for aqueous MO/sub 2//sup +/ ions. The differences in behavior observed between actinide(V) and -(VI) species in noncompexing media and in carbonate media may be related to possible hydrogen bonding between the oxygen of the actinide(V) oxycation and water molecules. 12 figures, 3 tables.« less
  • Elevated concentrations of U are found in agricultural drainage waters from the San Joaquin Valley, CA, which are often disposed of in evaporation basins that are frequented by waterfowl. To determine the factors that affect aqueous U concentrations in the basins, sorption experiments with U(VI) were performed at various CO{sub 2} partial pressures, dissolved Ca, Mg, and P concentrations, and carbonate alkalinities. Synthetic waters, comparable in inorganic constituents to irrigation and drainage waters, were prepared, spiked with 0.1 (soil) and 2 mg U(VI) L{sup -1} (synthetic goethite), and analyzed for U, P (when applicable), and major ions. Total chemical analysesmore » were input into the computer program FITEQL to determine U(VI) speciation and generate U(VI) adsorption constants with the diffuse layer model (also referred to as the two-layer model). Maximum adsorption occurred in solutions with low carbonate alkalinities (<=3 mmol L{sup -1}), ionic strengths (<=0.03 M), Ca concentrations (<=4 mmol L{sup -1}), and P concentrations (<0.005 mmol L{sup -1} for soil). Study results suggest that elevated U concentration in the drainage waters are due to the speciation of dissolved U(VI) into negatively charged carbonate complexes. 29 refs., 5 figs., 7 tabs.« less
  • The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonitemore » edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites (‘spillover’ effect).« less
  • Conditions were investigated for the electrochemical reduction of uranium(VI) to uranium(IV) in sodium carbonatebicarbonate solutions at mercury and platinum cathodes in a cell with cation exchange membranes separating cathode and anode compartments. A current density plateau was found only for the mercury cathode, in the potential range between --1.20 and --1.85 v vs SCE, which permits specific reduction of uranium(VI) with current efficiencies of over 80%. The reduction was performed so that no precipitation occurred in the electrolysis cell itself, the precipitation of uranium dioxide being carried out in a separate vessel. The possibilities of a large-scale process used basedmore » on the experimental work are discussed. (Uran. Abstr., 3: No. 2, Jan. 1964)« less