Decomposition mechanism of methylene blue caused by metallic iron-maghemite mixture

Shiro Kubuki, Koya Shibano, Kazuhiko Akiyama, Zoltán Homonnay, Erno Kuzmann, Mira Ristić, Tetsuaki Nishida

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Decomposition mechanism of methylene blue (MB) caused by a mixture of metallic iron-maghemite (Fe0-γFe2O3) was investigated by means of 57Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD), Ultraviolet-Visible Absorption Spectroscopy (UV-vis) and electrospray-ionization mass spectroscopy (ESI-MS). Ten day-leaching test of 10 μmol L- 1 MB aqueous solution and Fe0-γFe2O3 mixture (mass ratio 3:7) showed a decrease in the concentration from 10. 5 to 4. 45 μmol L- 1 with first-order rate constant (k) of 1.57 × 10 - 1 day -1. An ESI-MS study of Fe0-γFe2O3 mixture (3:7) after the leaching test revealed new peaks at m/z of 100, 110 and 137 due to fragmentation of MB, in addition to those observed at m/z of 284, 270 and 256 which were ascribed to MB, Azure B and Azure A, respectively. 57Fe-Mössbauer spectra of Fe0-γFe2O3 mixture (3:7) resulted in a decrease in absorption area (A) for Fe0 (δ = 0. 00±0. 01 mm s- 1, Hint = 33. 0±0. 1 T) from 37. 5 to 21. 3, 9. 7, 7. 9, 7. 0 and 4. 5±0. 5 %, together with an increase in A from 0. 0 to 5. 0, 13. 8, 17. 2, 21. 0 and 22. 4±0. 5 % for octahedral (Oh) iron (FeII + FeIII) of Fe3O4. XRD study of these samples indicated that the peak intensity at 2Θ of 44. 7° being ascribed to Fe0 was decreased, while that of 35. 6° due to Fe3O4 was almost constant; relative peak ratio of Fe0/Fe3O4 was decreased from 26. 3 to 2. 76 after the leaching, indicating that Fe0 in the Fe0-γFe2O3 mixture was oxidized to Fe3O4. These experimental results suggest that Fe0-γFe2O3 mixture could be utilized for the cleaning or decomposition of toxic organic compounds like trichloroethylene.

Original languageEnglish
Pages (from-to)47-52
Number of pages6
JournalHyperfine Interactions
Volume218
Issue number1-3
DOIs
Publication statusPublished - Jan 1 2013

Keywords

  • Electrospray ionization mass spectrometry (ESI-MS)
  • Fe-Mössbauer spectroscopy
  • Maghemite
  • Metallic iron
  • Methylene blue (MB) decomposition
  • Ultraviolet-Visible Absorption Spectroscopy (UV-vis)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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