TY  - JOUR
A1  - Marang, Laura
A1  - Eidner, Sascha
A1  - Kumke, Michael Uwe
A1  - Benedetti, Marc F.
A1  - Reiller, Pascal E.
T1  - Characterization of competitive binding of Eu(III)/Cu(II) and Eu(III)/Ca(II) to Gorleben humic acid
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/00167037
U6  - https://doi.org/10.1016/j.gca.2009.05.011
SN  - 0016-7037
ER  - 
TY  - JOUR
A1  - Marang, Laura
A1  - Eidner, Sascha
A1  - Kumke, Michael Uwe
A1  - Benedetti, Marc F.
A1  - Reiller, Pascal E.
T1  - Spectroscopic characterization of the competitive binding of Eu(III), Ca(II) and Cu(II) to a sedimentary originated humic acid
N2  - 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(Ill) 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.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/00092541
U6  - https://doi.org/10.1016/j.chemgeo.2009.03.003
SN  - 0009-2541
ER  - 
TY  - JOUR
A1  - Marang, Laura
A1  - Reiller, Pascal E.
A1  - Eidner, Sascha
A1  - Kumke, Michael Uwe
A1  - Benedetti, Marc F.
T1  - Combining spectroscopic and potentiometric approaches to characterize competitive binding to humic substances
N2  - In an area that contains high concentrations of natural organic matter, it is expected that it plays an important role on the behavior of rare earth elements (REE), like europium, and of trivalent actinides. Competitive interactions with H+, inorganic species, major cations, e.g. Ca(II) or Mg(II), could influence these metals transport and bioavailability. Competitive experiments between cations, which can bind differently to humic substances and Eu3+,will bring an improved understanding of the competitive mechanisms. The aim of this study is to acquire data for Eu(III)/Cu(II) and Eu(III)/Ca(II) competitive binding to a sedimentary originated humic acid (Gorleben, Germany). The NICA-Donnan parameters for Ca2+, Cu2+, and Eu3+ obtained from competitive binding experiments using Ca2+ or Cu2+ ion selective electrodes were used to model time-resolved laser fluorescence spectroscopy (TRLFS) measurements. Eu3+ and Cu2+ are in direct competition for the same type of sites,whereas Ca2+ has an indirect influence through electrostatic binding.
Y1  - 2008
UR  - http://pubs.acs.org/doi/full/10.1021/es702858p
U6  - https://doi.org/10.1021/Es702858p
ER  -