Transformation of solid Potassium Ferrate(VI) (K2FeC) 4): Mechanism and kinetic effect of air humidity

Libor Machala, Radek Zboril, Virender K. Sharnia, Jan Filip, Dalibor Jancik, Z. Homonnay

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The kinetics of solid-state transformation (aging) of potassium ferrate(VI) (K2FeO4) under various air-humidity conditions (55-95 % relative humidity) at room temperature were studied by in-situ Mössbauer spectroscopy. The kinetic data showed a significant increase in the decomposition rate with increasing air humidity. The decomposition kinetics is very unusual with two almost linear decay steps. The first slow decay was observable at rather lower humidity levels (55-70%) probably due to the formation of the narrow compact layer of nanoparticulate Fe(OH)3 reaction product. This layer limits the access of both H2O and CO2 participating in the reaction as the gaseous reactants. The second decay with much faster rate showed a nearly positive linear relationship with the humidity. The identification and characterization of the final products of aging were conducted by using X-ray diffraction (XRD), variable-temperature and in-field Mössbauer spectroscopy, magnetic measurements, thermogravimetry (TG) and differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) techniques. The reaction mechanism, assuming formation of KHCO3 and Fe(OH)3 in the molar ratio of 2:1 per 1 mol of solid K2FeO4 was suggested. The SEM images revealed the formation of large KHCO3 crystallites whose surface was covered by ultrasmall X-ray amorphous iron(III) hydroxide nanoparticles in a high degree of agglomeration. The obtained results of aging under humid conditions are important for the possible storage of K2FeC)4 and thus for its environmental and industrial applications.

Original languageEnglish
Pages (from-to)1060-1067
Number of pages8
JournalEuropean Journal of Inorganic Chemistry
Issue number8
DOIs
Publication statusPublished - Mar 2009

Fingerprint

Atmospheric humidity
Kinetics
Air
Aging of materials
Spectroscopy
Decomposition
Scanning electron microscopy
Magnetic variables measurement
Reaction products
Crystallites
Industrial applications
Thermogravimetric analysis
Differential scanning calorimetry
Agglomeration
potassium ferrate
Nanoparticles
X ray diffraction
X rays
Temperature
potassium bicarbonate

Keywords

  • Environmental chemistry
  • Iron
  • Moessbauer spectroscopy
  • Reaction mechanisms
  • Solid-state reactions

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Transformation of solid Potassium Ferrate(VI) (K2FeC) 4) : Mechanism and kinetic effect of air humidity. / Machala, Libor; Zboril, Radek; Sharnia, Virender K.; Filip, Jan; Jancik, Dalibor; Homonnay, Z.

In: European Journal of Inorganic Chemistry, No. 8, 03.2009, p. 1060-1067.

Research output: Contribution to journalArticle

Machala, Libor ; Zboril, Radek ; Sharnia, Virender K. ; Filip, Jan ; Jancik, Dalibor ; Homonnay, Z. / Transformation of solid Potassium Ferrate(VI) (K2FeC) 4) : Mechanism and kinetic effect of air humidity. In: European Journal of Inorganic Chemistry. 2009 ; No. 8. pp. 1060-1067.
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