A Study of Curium(III) Humate Complexation by Time Resolved Laser Fluorescence Spectroscopy (TRLFS)

Kim, J. I.; Wimmer, H.; Klenze, R.

doi:10.1524/ract.1991.54.1.35

Cited by 77 publications

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“…At this excitation wavelength, the direct excitation of the Cm 3 + aquoion is very low compared to the indirect excitation by energy transfer from the humate ligand to the complexed Cm. The selected emission wavelength (601 nm) corresponds to the Cm-humate complex, whereas the Cm 3+ aquoion has its emission maximum at 594 nm [22], The fluorescence intensity, corrected for background noise, can be set directly proportional to the Cm-humate concentration. Extrapolation of the fluorescence intensity to very high humic acid concentrations, where all Cm(III) is complexed, gives the specific fluorescence intensity of Cm-humate for the given set-up and experimental conditions.…”

Section: Methodsmentioning

confidence: 99%

Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods

Kim

Rhee²,

Wimmer³

et al. 1993

Radiochimica Acta

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The complexation of trivalent metal ions with humic acid has been studied at pH 4 and 5 in 0.1 Μ NaC10 4 by three different experimental methods, i.e. UV spectroscopy, time resolved laser fluorescence spectroscopy (TRLFS) and ultrafiltration. The direct speciation of the metal ion and its humate complex in the reaction process has been made by UV spectroscopy for Am(III) in the micromolar concentration range and by TRLFS for Cm(III) in the nanomolar concentration range. The ultrafiltration is used with the lowest pore size of filter (ca. 1 nm) to separate the uncomplexed metal ion from its complexed species. The concentrations of both metal ion and humic acid are varied in such a manner that the effective functional groups of the humic acid becomes loaded with metal ions from 1 % to nearly 100%. The loading capacity of the humic acid for the trivalent metal ion, determined separately at each pH, is introduced into the evaluation of complexation constants. The variation of the metal ion concentration from 6 χ 10" 8 mol/1 to 4 χ 10" 5 mol/1 does not show any effect on the complexation reaction. The three different methods give rise to constants being comparable with one another. The average value of the constants thus determined is log β = 6.24 + 0.28 for the trivalent actinide ions.

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Section: Methodsmentioning

confidence: 99%

Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods

Kim

Rhee²,

Wimmer³

et al. 1993

Radiochimica Acta

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“…Therefore, the physiochemical characterization of HA in water and at mineral/water interfaces is of primary importance for the safety assessment of nuclear waste repositories. 3,4 The chemical parameters of the aqueous medium, such as pH, ionic strength and the presence of metal ions, determine the surface charges of HA and minerals and therefore will influence adsorption and aggregation phenomena.…”

Section: Introductionmentioning

confidence: 99%

Influence of europium(III) on the adsorption of humic acid onto mica studied by AFM

Plaschke

Römer

Klenze

et al. 2000

Surf. Interface Anal.

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The importance of humic colloids influencing mobilization or immobilization of metal ions, i.e. actinides, in natural aquatic systems has been emphasized in the context of safety aspects of nuclear waste repositories. The influence of polyvalent cations, i.e. Eu(III) as a homologue for trivalent actinides, on the adsorption of humic acid (HA) onto the basal plane of cleaved muscovite is studied by atomic force microscopy (AFM). To avoid denaturation of sorbed HA by drying procedures, the investigation is performed in aqueous medium by applying non-contact-mode AFM (also called fluid-tapping-mode AFM). Nanostructure, surface coverage and dimensions of sorbed HA are found to be influenced by Eu(III) ions. To get a basic understanding of the interaction between HA and the mica crystalline plane, force spectroscopy experiments are performed. Force versus distance curves are recorded with and without the presence of Eu(III) ions using AFM tips covered with HA. It is found that in the presence of Eu(III) binding forces between HA and the mica surface increase by about one order of magnitude. This effect is partly reversible in deionized water and fully reversible in EDTA solution. On the basis of these observations, polyvalent cation bridges can be favoured as the binding mechanism between HA and mica planes.

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“…Both elements form insoluble hydroxides which are strongly sorbed by surfaces. Americium and curium are also known for the formation of stable complexes with organic ligands [230,[298][299][300][301][302][303]. Pimpl [287] gave the following decreasing sequence for soil/plant transfer:…”

Section: Specific Radionuclidesmentioning

confidence: 99%

Speciation of Radionuclides in the Environment

Gunten

Beneš

1995

Radiochimica Acta

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Methods for the determination of the speciation of radionuclides in aerosols, in aquatic solutions, in sediments, soils and rocks are reviewed. At present, most of the results about speciation are deduced from model calculations, model experiments, and separation of species (forms) of radionuclides, e.g., by sequential extraction procedures. Methods of direct determination of speciation of radionuclides (e.g., by laser induced spectroscopy) are in general not yet sensitive enough for a measurement of the very low concentrations of radionuclides in the environment. The methodological part of this paper is followed by a review of the very abundant literature about speciation of important radionuclides in the environment, i.e., in the atmosphere, hydrosphere and lithosphère. The review does not include the biosphere. Literature up to spring 1993 is included (with a few more recent additions).

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A Study of Curium(III) Humate Complexation by Time Resolved Laser Fluorescence Spectroscopy (TRLFS)

Cited by 77 publications

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Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods

Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods

Influence of europium(III) on the adsorption of humic acid onto mica studied by AFM

Speciation of Radionuclides in the Environment

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A Study of Curium(III) Humate Complexation by Time Resolved Laser Fluorescence Spectroscopy (TRLFS)

Cited by 77 publications

References 0 publications

Complexation of Trivalent Actinide Ions (Am3+, Cm3+) with Humic Acid: A Comparison of Different Experimental Methods

Complexation of Trivalent Actinide Ions (Am3+, Cm3+) with Humic Acid: A Comparison of Different Experimental Methods

Influence of europium(III) on the adsorption of humic acid onto mica studied by AFM

Speciation of Radionuclides in the Environment

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Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods

Complexation of Trivalent Actinide Ions (Am³⁺, Cm³⁺) with Humic Acid: A Comparison of Different Experimental Methods