THE OXIDATION OF FE(OH)(2) IN THE PRESENCE OF CARBONATE IONS - STRUCTURE OF CARBONATE GREEN RUST ONE

被引:28
作者
DRISSI, H
REFAIT, P
GENIN, JMR
机构
[1] Laboratoire de Chimie Physique pour l'Environnement, Groupe de Spectrométrie Mössbauer, UMR 9992 CNRS, Université H. Poincaré
[2] Département Sciences des Matériaux, ESSTIN, Villers-Nancy, F-54600
来源
HYPERFINE INTERACTIONS | 1994年 / 90卷 / 1-4期
关键词
D O I
10.1007/BF02069145
中图分类号
O64 [物理化学(理论化学)、化学物理学]; O56 [分子物理学、原子物理学];
学科分类号
070203 ; 070304 ; 081704 ; 1406 ;
摘要
Sodium carbonate Na2CO3 is added to a solution containing an Fe(OH)(2) precipitate in order to study the influence of CO32- ions on the oxidation of ferrous hydroxide. The first stage of the reaction leads to a ferrous-ferric compound, the carbonate green rust one (GR1), identified by its X-ray diffraction pattern. The Mossbauer spectrum at 78 K of this GR1 displays two ferrous doublets and one ferric doublet in the 3: 1:2 abundance ratio. The quadrupole splittings QS are 2.91, 2.58 and 0.42 mm/s, respectively, and the isomer shifts IS are 1.25, 1.25 and 0.47 mm/s respectively. These values are very dose to those of the three doublets of the chloride GR1, 3Fe(OH)(2)Cl.Fe(OH)(2)Cl.nH(2)O. This fact confirms that the crystallographic structures of these two GR1s are similar, formed by the stacking of hydroxide layers and interlayers containing the considered anions (Cl- or CO32-) and water molecules. The chemical formula of carbonate Gel is Fe-4((II))Fe-2((III))(OH)(12)CO3.nH(2)O, and its standard chemical potential -853 900 cal/mol if n = 0. The second stage of the reaction is the oxidation of GR1, which leads to alpha-FeOOH goethite.
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页码:395 / 400
页数:6
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