氧化状态和铁在nontronite的结构:从氧化到减少条件
Yanting Qian1,2, Andreas C Scheinost3,4, Sylvain Grangeon5
1Laboratory for Waste Management, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
概括
自然的粘土矿物是地球的关键.
科学领域:
- 地质化学 地质化学
- 矿物学是一门学科.
- 环境科学 环境科学
背景情况:
- 粘土矿物质,特别是含铁的矿物质,对于控制地球关键区域的元素循环至关重要.
- 在还原条件下了解粘土矿物质的行为对于氧化还原反应机制至关重要.
- 在不同的氧化还原状态下,nontronite的结构变化仍然不太清楚.
研究的目的:
- 为了研究不同氧化还原条件下铁质非矿的结构性行为.
- 为了比较多种方法来确定粘土矿物中的铁氧化还原状态.
- 为了阐明铁的减少对nontronite的结构的影响.
主要方法:
- 使用酸盐-二碳酸盐-二酸盐 (CBD) 方法进行化学降解.
- 使用57Fe Mössbauer光谱,XPS,XANES和MEO/MER来确定铁的氧化还原状态.
- 使用X射线衍射 (XRD) 和传输电子显微镜 (TEM) 的结构分析.
- 使用扩展的X射线吸收细结构 (EXAFS) 谱学进行短距离顺序分析.
主要成果:
- 多种光谱方法一致确定了Fe (II) /Fe (III) 的比率.
- 长距离的nontronite结构在很大程度上保持不变,直到44%的Fe (II) 减少,表面溶解较小.
- EXAFS揭示了结构性障碍的增加和Fe集群与增强的减少.
结论:
- 非特罗尼特的长距离结构对显著的铁减少具有弹性.
- 短距离的结构变化,包括混乱和Fe聚类,在减少时发生.
- 通过组合光谱技术可以实现精确的Fe氧化还原状态的确定.
相关概念视频
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