Effect of pH and uranium concentration on interaction of uranium(VI) and uranium(IV) with organic ligands in aqueous solutions

Li, W. C.; Victor, D.M.; Chakrabarti, C. L.

doi:10.1021/ac50053a033

Cited by 119 publications

(54 citation statements)

References 12 publications

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“…Furthermore, one can notice that there is a marked difference between the experimental data form different authors for uranium (VI) under low CO 2 (g) partial pressure. 14 Nevertheless, in the case of uranium, neither the results of Li et al [102], nor those from Artinger et al [26] could be assessed by this exercise. In the latter study, the authors did not observe any difference in the behaviour of uranium, introduced as uranium (VI) or uranium (IV), neither with purified HA [102], nor with Gorleben groundwater in the presence of natural organic matter at varying E H [26].…”

Section: Application To Redox Sensitive Actinide Elementsmentioning

confidence: 88%

“…14 Nevertheless, in the case of uranium, neither the results of Li et al [102], nor those from Artinger et al [26] could be assessed by this exercise. In the latter study, the authors did not observe any difference in the behaviour of uranium, introduced as uranium (VI) or uranium (IV), neither with purified HA [102], nor with Gorleben groundwater in the presence of natural organic matter at varying E H [26]. 15 Under these conditions, the uranium speciation would predict U(OH) 4 HA(I) as predominant species up to E H = -20 mV/SHE, and carbonate uranium (VI) complexes for higher potentials (data not shown).…”

Section: Application To Redox Sensitive Actinide Elementsmentioning

confidence: 88%

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Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Reiller¹

2005

Radiochimica Acta

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To cite this version:Pascal E. Reiller. Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model. AbstractThe complexation of redox sensitive elements by humic acid (HA), described through the charge neutralisation model (CNM) has been reviewed in order to have a comprehensive scope. The data acquired in HUMICS program on thorium (IV), and data available in the literature, were reinterpreted according to the CNM, and adapted to uranium (IV), neptunium (IV) and plutonium (IV) through analogy in order to draw a boundary prediction. Otherwise, available data obtained in the framework of the CNM were used, or adapted if necessary, for other redox states when the analogy is justified, i.e. Am The obtained speciation diagrams indicate that, when (HA) = 100 mg/L, redox sensitive actinides should be reduced to their +IV state when E H ≤ 650 mV/SHE for plutonium, E H ≤ 100 mV/SHE for neptunium and E H ≤ -20 mV/SHE for U. Plutonium could be present as mixtures of plutonium (III) and (IV) depending on the pH value in reducing ground waters -150 ≤ E H (mV/SHE) ≤ 150. The known reduction of neptunium (V) to neptunium (IV) in Gorleben ground waters seems also well represented, so does the stability of uranium (VI) in humic solution when E H ≥ 100 mV/SHE. Conversely, the known association of plutonium (VI) in marine systems are not satisfactorily represented, so does is the uranium behaviour under reducing conditions. Experiments under well-controlled conditions are still needed to ascertain the plutonium and uranium comportment in the presence of humic acid. *

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Section: Application To Redox Sensitive Actinide Elementsmentioning

confidence: 88%

Section: Application To Redox Sensitive Actinide Elementsmentioning

confidence: 88%

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Reiller¹

2005

Radiochimica Acta

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“…Another possibility is that humic materials may complex U(VI) (Moulin et al, 1992;Higgo et al, 1993;Lenhart et al, 2000), decrease bioavailability and inhibit bioreduction. Finally, humic materials may also complex U(IV) (Li et al, 1980;Zeh et al, 1997), which could interfere with U(IV) precipitation and facilitate U(IV) transport. The objective of this study was to examine the effect of humic acid on the bioreduction of U(VI).…”

Section: Introduction Umentioning

confidence: 99%

Soil Humic Acid Decreases Biological Uranium(VI) Reduction by Shewanella putrefaciens CN32

Burgos

Senko

Dempsey

et al. 2007

Environmental Engineering Science

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Biological reduction of uranium(VI) by Shewanella putrefaciens CN32 was investigated in the presence of soil humic acid (SHA). Experiments were performed under resting cell conditions with uranyl acetate as the electron acceptor and sodium lactate as the electron donor in a NaHCO 3 or PIPES/NaHCO 3 buffer. SHA significantly decreased the final extent of U(VI) bioreduction (100% uranium bioreduced without humics vs. 50% uranium bioreduced with humics). Dissolved (0.2-m filter) U(VI) was measured by kinetic phosphorescence analysis where samples were kept anoxic during one measurement, and split samples were oxidized and remeasured. The difference between the anoxic and oxidized measurements was operationally defined as "U(IV) Ͻ 0.2-m." U(IV) Ͻ0.2-m was detected only in samples containing SHA suggesting that soluble U(IV)-SHA complexes were formed or SHA facilitated the transport of U IV O 2 (s) nanoparticles through the filter. Identical experiments conducted with nitrate instead of U(VI) showed that SHA interrupted electron transport to nitrate, and may interact similarly with U(VI). These results suggest that humic materials may influence U immobilization by decreasing U(VI) reduction and enhancing the solubility of U(IV).

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“…In less acidic conditions, various uranium (VI) carbonate complexes tend to exist and increase uranium (VI) solubility. Uranium (VI) also forms stable complexes with dissolved organic carbon and also binds effectively with iron and manganese oxides and clays (Li et al, 1980). Studies of the Tims Branch -Steed Pond system have found that the greatest percentage of the uranium mobilized during storm events is associated with chemically labile forms (Batson et al, 1996).…”

Section: A32 Contaminant Speciationmentioning

confidence: 99%

Research Opportunities for Studies of Contaminant Transport in Fluvial Systems at the TIMS Branch - Steed Pond System, Savannah River Site

Looney¹

2003

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Effect of pH and uranium concentration on interaction of uranium(VI) and uranium(IV) with organic ligands in aqueous solutions

Cited by 119 publications

References 12 publications

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Soil Humic Acid Decreases Biological Uranium(VI) Reduction by Shewanella putrefaciens CN32

Research Opportunities for Studies of Contaminant Transport in Fluvial Systems at the TIMS Branch - Steed Pond System, Savannah River Site

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