Characterization of the intermediate in formation of selenate-substituted ettringite
Characterization of the intermediate in formation of selenate-substituted ettringite
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DOI：
10.1016/j.cemconres.2017.05.002
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发表时间：
2017-09-01
影响因子：
11.4
通讯作者：
Hirajima, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Guo, Binglin;Sasaki, Keiko;Hirajima, Tsuyoshi
在碱性条件下沉淀SeO_（42-）取代的钙矾石是一种有效的方法。由于SO 42-是水和土壤环境中的主要离子之一，且易与钙矾石结合，因此研究了SO 42-对SeO 42-固定化的影响。本文旨在系统地阐明有无SO 42-存在下SeO 42-取代钙矾石的形成机理。当SO 42-和SeO 42-共存时，加入Ca源后，两种含氧阴离子立即与钙矾石共沉淀。虽然SeO 42-部分取代了钙矾石中的SO 42-，但在此过程中没有形成其他相。没有SO 42-SeO 42-取代的AFm相作为中间体形成，通过在d 2.878处的X-射线衍射峰以及通过扫描电子显微镜与能量色散X-射线光谱和zeta电位测量确认。研究表明，SeO_（42-）在钙矾石中的掺入机制与水环境中共存的SO_（42-）有关。
Precipitation of SeO42--substituted ettringite is an efficient method to immobilize SeO42- under alkaline conditions. The effect of SO42- on SeO42- immobilization was investigated, because SO42- is one of the major ions in aqueous and soil environments and it is easily incorporated in ettringite. We aimed to systemically elucidate the formation mechanisms of SeO42--substituted ettringite with and without SO42-. When SO42- and SeO42- coexisted, both oxoanions were immediately coprecipitated with ettringite after adding a Ca source. Although SO42- was partially substituted by SeO42- in ettringite, no other phases were formed during the process. Without SO42- SeO42--substituted AFm phase was formed as an intermediate, confirmed by X-ray diffraction peak at d 2.878, as well as by scanning electron microscopy with energy dispersive X-ray spectroscopy and zeta potential measurements. It is clear that the incorporation mechanism of SeO42- in ettringite is dependent on coexisting SO42- in aqueous environments.