Science China Chemistry

, Volume 55, Issue 9, pp 1699–1704 | Cite as

Electrochemical behavior of [UO2Cl4]2− in 1-ethyl-3-methylimidazolium based ionic liquids

  • Toshinari Ogura
  • Kotoe Sasaki
  • Koichiro Takao
  • Tsuyoshi Arai
  • Yasuhisa Ikeda
Articles Special Topic Nuclear Fuel Cycle Chemistry

Abstract

In order to examine the chemical form of uranyl species in 1-ethyl-3-methylimidazolium (EMI) based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2Cl4] into a mixture of EMICl and EMIBF4 (50:50 mol%) were measured. As a result, it was confirmed that uranyl species in the mixture of EMICl and EMIBF4 existed as [UO2Cl4]2−. Cyclic voltammograms (CVs) of [UO2Cl4]2− in the mixture were measured at 25 °C using a Pt working electrode, a Pt wire counter electrode, and an Ag/Ag+ reference electrode (0.01 M AgNO3, 0.1 M tetrabutylammonium perchlorate in acetonitrile) in a glove box under an Ar atmosphere. Peaks corresponding to one redox couple were observed around −1.05 V (Epc) and −0.92 V (Epa) vs. ferrocene/ferrocenium ion (Fc/Fc+). The potential differences between two peaks (ΔEp) increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s−1, while the (Epc + Epa)/2 value was constant, −0.989 V vs. Fc/Fc+ regardless of the scan rate. Furthermore, the diffusion coefficient of [UO2Cl4]2− and the standard rate constant were estimated to be 3.7 × 10−8 cm2 s−1 and (2.7–2.8) × 10−4 cm s−1 at 25 °C. By using the diffusion coefficient and the standard rate constant, the simulation of CVs was performed based on the reaction, [UO2Cl4]2− + e = [UO2Cl4]3−. The simulated CVs were found to be consistent with the experimental ones. From these results, it is concluded that [UO2Cl4]2− in the mixture of EMICl and EMIBF4 is reduced to [UO2Cl4]3− quasi-reversibly at −0.989 V vs. Fc/Fc+.

Keywords

uranyl chloride ionic liquids electrochemistry cyclic voltammetry 

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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Toshinari Ogura
    • 1
  • Kotoe Sasaki
    • 2
  • Koichiro Takao
    • 3
  • Tsuyoshi Arai
    • 2
  • Yasuhisa Ikeda
    • 1
  1. 1.Research Laboratory for Nuclear ReactorsTokyo Institute of TechnologyTokyoJapan
  2. 2.Department of Materials ScienceShibaura Institute of TechnologyTokyoJapan
  3. 3.Department of Materials and Life ScienceSeikei UniversityTokyoJapan

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