January 6, 2020 Dataset Open Access

Lösch, Henry; Raiwa, Manuel; Jordan, Norbert; Steppert, Michael; Steudtner, Robin; Stumpf, Thorsten; Huittinen, Nina Maria

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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>Lösch, Henry</dc:creator>
  <dc:creator>Raiwa, Manuel</dc:creator>
  <dc:creator>Jordan, Norbert</dc:creator>
  <dc:creator>Steppert, Michael</dc:creator>
  <dc:creator>Steudtner, Robin</dc:creator>
  <dc:creator>Stumpf, Thorsten</dc:creator>
  <dc:creator>Huittinen, Nina Maria</dc:creator>
  <dc:date>2020-01-06</dc:date>
  <dc:description>In this study the complexation of U(VI) with orthosilicic acid (H4SiO4) between pH 3.5 and 5 with electrospray ionization mass spectrometry (ESI‒MS) and laser‒induced luminescence spectroscopy was comprehensively characterized. The ESI‒MS experiments performed at a total silicon concentration of 5∙10‒5 M (exceeding the solubility of amorphous silica at both pH‒values) revealed the formation of oligomeric sodium‒silicates in addition to the UO2OSi(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 NaClO4. The results confirmed the formation of the aqueous UO2OSi(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 *β0 = ‒0.06 ± 0.24. Further experiments at different temperatures (1 – 25 °C) allowed the calculation of the molal enthalpy of reaction ΔrHm0 = 45.8 ± 22.5 kJ∙mol‒1 and molal entropy of reaction ΔrSm0 = 152.5 ± 78.8 J∙K‒1∙mol‒1 using the van’t Hoff equation, corroborating an endothermic and entropy driven complexation process.</dc:description>
  <dc:identifier>https://rodare.hzdr.de/record/211</dc:identifier>
  <dc:identifier>10.14278/rodare.211</dc:identifier>
  <dc:identifier>oai:rodare.hzdr.de:211</dc:identifier>
  <dc:language>eng</dc:language>
  <dc:relation>url:https://www.hzdr.de/publications/Publ-29643</dc:relation>
  <dc:relation>doi:10.14278/rodare.210</dc:relation>
  <dc:relation>url:https://rodare.hzdr.de/communities/rodare</dc:relation>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>https://creativecommons.org/licenses/by/4.0/legalcode</dc:rights>
  <dc:subject>luminescence</dc:subject>
  <dc:subject>silicates</dc:subject>
  <dc:subject>Uranium(VI)</dc:subject>
  <dc:subject>complexation</dc:subject>
  <dc:subject>thermodynamic constants</dc:subject>
  <dc:subject>temperature dependent</dc:subject>
  <dc:title>Temperature‒dependent luminescence spectroscopic and mass spectrometric investigations of U(VI) complexation with aqueous silicates in the acidic pH‒range</dc:title>
  <dc:type>info:eu-repo/semantics/other</dc:type>
  <dc:type>dataset</dc:type>
</oai_dc:dc>