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Spectroscopic characterization of the competitive binding of Eu(III), Ca(II), and Cu(II) to a sedimentary originated humic acid

Abstract : The competition between REE, alkaline earth and d-transition metals for organic matter binding sites is still an open field of research; particularly, the mechanisms governing these phenomena need to be characterized in more detail. In this study, we examine spectroscopically the mechanisms of competitive binding of Eu(III)/Cu(II) and Eu(III)/Ca(II) pair to Gorleben humic acid (HA), as previously proposed in the framework of the NICA-Donnan model. The evolution of time-resolved laser induced luminescence spectra of humic-complexed Eu(III) showed two strikingly different environments for a comparable bound proportion for Cu(II) and Ca(II). Cu(II) seems to compete more effectively with Eu(III) inducing its release into the Donnan phase, and into the bulk solution as free Eu3+. This is evidenced both by the shapes of the spectra and by the decrease in the luminescence decay times. In contrast with that, Ca(II) induces a modification of the HA structure, which enhances the luminescence of humic-bound Eu(III), and causes a minor modification of the chemical environment of the complexed rare earth ion.
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https://hal-cea.archives-ouvertes.fr/cea-00402976
Contributor : Pascal Reiller <>
Submitted on : Wednesday, July 8, 2009 - 5:15:57 PM
Last modification on : Thursday, June 25, 2020 - 2:54:34 PM

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L. Marang, Sascha Eidner, Michael Kumke, Marc Benedetti, Pascal E. Reiller. Spectroscopic characterization of the competitive binding of Eu(III), Ca(II), and Cu(II) to a sedimentary originated humic acid. Chemical Geology, Elsevier, 2009, 264 (1-4), pp.154-161. ⟨10.1016/j.chemgeo.2009.03.003⟩. ⟨cea-00402976⟩

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