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Title of article :
Formation of green rust via mineralogical transformation of ferric oxides (ferrihydrite, goethite and hematite)
Author/Authors :
Usman، نويسنده , , M. and Hanna، نويسنده , , K. and Abdelmoula، نويسنده , , M. and Zegeye، نويسنده , , A. and Faure، نويسنده , , P. and Ruby، نويسنده , , C.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2012
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Abstract :
This laboratory study describes the abiotic mineralogical transformation of ferrihydrite (F), goethite (G) and hematite (H) into mixed FeII–FeIII green rust (GR). Stoichiometric quantities of ferric oxides were reacted with hydroxylated FeII species under static batch conditions at a final pH of ~ 6.3 for 2 h. Mössbauer spectroscopy and transmission electron microscopy (TEM) was used to characterize initial and resulting transformation products. Results indicate that the order of reactivity to transform into GR is F > G > H. Complete transformation of F into GR was achieved while about half of G or H was transformed although G or H are known for their higher thermodynamic stability. As expected, the concentration of soluble iron at the end of the experiment followed the order H > G > F which is in agreement with the predictions of the FeII–FeIII mass balance diagram. The formation kinetics of GR is much higher than that observed for magnetite (Fe3O4) under similar experimental conditions. Therefore in the environment, when hydroxylated FeII species interact with ferric oxides, fougerite, the mineral counter part of GR, could be preferentially formed.
Keywords :
Iron , Green rust , Mِssbauer , Fougerite , layered double hydroxides
Journal title :
Applied Clay Science:an International Journal on the Application...
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