Fougerite Fe^II???III oxyhydroxycarbonate in environmental chemistry and nitrate reduction

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• 作者：J.-M. R. G¨¦nin ; A. Renard and Ch. Ruby
• 关键词：FeII  ; − ;   ; III (oxy)hydroxycarbonate ; Green rust ; M?ssbauer spectroscopy ; Fougerite
• 刊名：Hyperfine Interactions
• 出版年：2008
• 出版时间：September, 2008
• 年：2008
• 卷：186
• 期：1-3
• 页码：31-37
• 全文大小：328.5 KB

文摘

The identification of the fougerite mineral responsible for the bluish-green shade of gleysols in aquifers as being the FeII − III oxyhydroxycarbonate \textGR(\textCO₃2-)*\text{GR}(\text{CO}_{3}^{2-})^* of formula, [\textFeII_6x\textFeIII_{6(1 - x)}\textO₁₂\textH_2(7-3x)]2+¡¤[\textCO₃2-¡¤3\textH₂\textO]2-[\text{Fe}^{\rm II}_{6x}\text{Fe}^{\rm III}_{6(1 - x)}\text{O}_{12}\text{H}_{2(7-3x)}]^{2+}\bullet[\text{CO}_{3}^{2-}\bullet3\text{H}_{2}\text{O}]^{2-} where the ferric molar ratio x = [FeIII/Fe_total] is restricted to the domain [1/3–2/3] induces to study the reactivity of the synthetic green rust for reducing some major pollutants. The oxidation within the solid compound \textGR(\textCO₃2-)*\text{GR}(\text{CO}_{3}^{2-})^* in the presence of nitrates is followed by miniaturized M?ssbauer spectrometer (MIMOS). Ratio x = [FeIII/Fe_total] increases up to 0.67 where \textGR(\textCO₃2-)*\text{GR}(\text{CO}_{3}^{2-})^* transforms gradually into magnetite. This could well explain the composition variability of fougerite occurrences.