In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface.
In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface.
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DOI：
10.1021/es5051925
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发表时间：
2015-01
影响因子：
11.4
通讯作者：
K. Müller;Annett Gröschel;A. Roßberg;F. Bok;C. Franzen;V. Brendler;H. Foerstendorf
中科院分区：
文献类型：
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作者：
K. Müller;Annett Gröschel;A. Roßberg;F. Bok;C. Franzen;V. Brendler;H. Foerstendorf
赤铁矿在调节岩石和土壤中污染物的迁移中起着决定性的作用。采用原位振动光谱、x射线吸收光谱和表面络合模拟相结合的方法对赤铁矿-水界面上的Np(V)反应进行了全面研究。考虑了各种吸附参数，如Np(V)浓度、pH、离子强度和碳酸氢盐的存在。时间分辨红外光谱吸附实验证明，在氧化铁-水界面形成了一个单一的单体Np(V)球内吸附配合物。EXAFS提供了关于双齿共享边缘协调的补充信息。在大气衍生的碳酸氢盐存在的情况下，证实了双碳酸盐内球复合物的形成，支持了先前的EXAFS发现获得的分子结构允许对近期和未来宏观数据进行更可靠的表面络合建模。这种可靠的模型对于评价水污染和预测放射性污染物在地下环境中的命运和迁移是强制性的，因为它可能发生在放射性废物储存库或后处理工厂附近。
Hematite plays a decisive role in regulating the mobility of contaminants in rocks and soils. The Np(V) reactions at the hematite-water interface were comprehensively investigated by a combined approach of in situ vibrational spectroscopy, X-ray absorption spectroscopy and surface complexation modeling. A variety of sorption parameters such as Np(V) concentration, pH, ionic strength, and the presence of bicarbonate was considered. Time-resolved IR spectroscopic sorption experiments at the iron oxide-water interface evidenced the formation of a single monomer Np(V) inner-sphere sorption complex. EXAFS provided complementary information on bidentate edge-sharing coordination. In the presence of atmospherically derived bicarbonate the formation of the bis-carbonato inner-sphere complex was confirmed supporting previous EXAFS findings.1 The obtained molecular structure allows more reliable surface complexation modeling of recent and future macroscopic data. Such confident modeling is mandatory for evaluating water contamination and for predicting the fate and migration of radioactive contaminants in the subsurface environment as it might occur in the vicinity of a radioactive waste repository or a reprocessing plant.