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Tytuł:
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Temperature-dependent luminescence spectroscopic and mass spectrometric investigations of U(VI) complexation with aqueous silicates in the acidic pH-range.
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Autorzy:
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Lösch H; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Raiwa M; Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Jordan N; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Steppert M; Institute of Radioecology and Radiation Protection, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Steudtner R; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Stumpf T; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Huittinen N; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany. Electronic address: .
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Źródło:
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Environment international [Environ Int] 2020 Mar; Vol. 136, pp. 105425. Date of Electronic Publication: 2020 Jan 31.
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Typ publikacji:
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Journal Article; Research Support, Non-U.S. Gov't
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Język:
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English
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Imprint Name(s):
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Publication: : Amsterdam : Elsevier Science
Original Publication: Oxford; Elmsford, N. Y., Pergamon Press.
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MeSH Terms:
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Luminescence*
Silicates*
Hydrogen-Ion Concentration ; Spectrum Analysis ; Temperature
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Contributed Indexing:
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Keywords: Complexation; Luminescence; Silicates; Temperature dependent; Thermodynamic constants; Uranium(VI)
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Substance Nomenclature:
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0 (Silicates)
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Entry Date(s):
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Date Created: 20200203 Date Completed: 20200910 Latest Revision: 20200910
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Update Code:
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20240105
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DOI:
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10.1016/j.envint.2019.105425
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PMID:
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32007922
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In this study the complexation of U(VI) with orthosilicic acid (H 4 SiO 4 ) was investigated between pH 3.5 and 5 by combining electrospray ionization mass spectrometry (ESI-MS) and laser-induced luminescence spectroscopy. The ESI-MS experiments performed at a total silicon concentration of 5 · 10 -3 M (exceeding the solubility of amorphous silica at both pH-values) revealed the formation of oligomeric sodium-silicates in addition to the UO 2 OSi(OH) 3 + species. For the luminescence spectroscopic experiments (25 °C), the U(VI) concentration was fixed at 5 · 10 -6 M, the silicon concentration was varied between 1.3 · 10 -4 -1.3 · 10 -3 M (reducing the formation of silicon oligomers) and the ionic strength was kept constant at 0.2 M NaClO 4 . The results confirmed the formation of the aqueous UO 2 OSi(OH) 3 + complex. The conditional complexation constant at 25 °C, log *β = -(0.31 ± 0.24), was extrapolated to infinite dilution using the Davies equation, which led to log *β 0 = -(0.06 ± 0.24). Further experiments at different temperatures (1-25 °C) allowed the calculation of the molal enthalpy of reaction Δ r H m 0 = 45.8 ± 22.5 kJ·mol -1 and molal entropy of reaction Δ r S m 0 = 152.5 ± 78.8 J·K -1 ·mol -1 using the integrated van't Hoff equation, corroborating an endothermic and entropy driven complexation process.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)
