Kinetics of nitrate reduction by green rusts—effects of interlayer anion and Fe(II):Fe(III) ratio

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• 作者：Hansen ; Hans Christian Bruun ; Guldberg ; Susanne ; Erbs ; Marianne ; et. al.
• 关键词：green rust ; layered double hydroxides ; nitrate ; ammonia ; nitrate reduction ; iron(II) ; M&ouml ; ssbauer spectroscopy
• 刊名：Applied Clay Science
• 出版年：2001
• 期刊代码：5_01691317
• 类别：ms
• 出版时间：January, 2001
• 卷：18
• 期：1-2
• 页码：81-91
• 文件大小：192 K

摘要

The reaction between the synthetic chloride form of green rust (GR) with an Fe(II):Fe(III) ratio of 3:1 (GRb>Clb>, Feb>4.5b>^IIFeb>1.5b>^III(OH)b>12b>Clb>1.5b>xHb>2b>O) and nitrate has been studied at GRb>Clb> concentrations up to 2.5 mM and nitrate concentrations from 0.7 to 14.2 mM in non-buffered aqueous suspensions under an argon atmosphere. Nitrate is reduced stoichiometrically to ammonium while GRb>Clb> is oxidized to magnetite with concurrent decrease of pH from 8.2 to 6.1. No nitrate reduction was observed in homogenous Fe(II) solutions at neutral pH. The rates of ammonium formation and consumption of Fe(II) in GRb>Clb> (Fe(II)b>GRb>) are well described by first-order reaction kinetics. No clear rate dependence with respect to nitrate was found, but it appears that above a nitrate concentration of approximately 7 mM and at fixed concentrations of Fe(II)b>GRb>, the rate of nitrate reduction is almost constant and independent of the nitrate concentration. Under these conditions, the rate law may be given by: <b>Formula Not Shownb> where k