Scorodite precipitation in the presence of antimony
Scorodite precipitation in the presence of antimony
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DOI：
10.1016/j.chemgeo.2015.04.013
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发表时间：
2015-06
期刊：
影响因子：
3.9
通讯作者：
D. Kossoff;Mark D. Welch;K. Hudson-Edwards
中科院分区：
文献类型：
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作者：
D. Kossoff;Mark D. Welch;K. Hudson-Edwards
研究了 Sb 对合成臭葱石沉淀以及所形成的所得相的影响。使用臭葱石合成方法制备了九种具有不同浓度 Sb 的合成沉淀物以及纯 As 和纯 Sb 端元，并使用 XRD、SEM、化学消化和 μXRF 绘图对这些沉淀物进行了表征。 XRD分析表明，端元为臭葱石(FeAsO4·2H2O)和三茂石(FeSbO4)，中间元不是Sb取代的臭葱石，而是臭葱石和三茂石的物理混合物，且随着合成中Sb量的增加，三茂石变得更加突出。对天然臭葱石的电子探针分析证实，它们含有的锑浓度可以忽略不计。随着合成中锑含量的增加，臭葱石的形态从共生晶体的玫瑰花结转变为较小微晶的上反体块。随着锑含量的增加，该系列的化学消解也变得越来越困难。我们得出的结论是，Sb 没有被臭葱石吸收（可能是由于其离子半径较大，并且与 As 相比，其与 O 的配位不同），系统中 Sb 含量的增加会影响臭葱石的形态，而三水石是一种高度稳定且可能被低估的 Sb 汇。
The effects of Sb on the precipitation of synthetic scorodite, and the resultant phases formed, were investigated. Nine synthetic precipitates with varying concentrations of Sb, together with As-only and Sb-only end members, were prepared using a scorodite synthesis method, and these were characterised using XRD, SEM, chemical digestion and μXRF mapping. XRD analysis shows that the end members are scorodite (FeAsO4·2H2O) and tripuhyite (FeSbO4), and that the intermediate members are not Sb-substituted scorodite, but instead are physical mixtures of scorodite and tripuhyite, with tripuhyite becoming more prominent with increasing amounts of Sb in the synthesis. Electron microprobe analysis on natural scorodites confirms that they contain negligible concentrations of Sb. With increasing Sb in the synthesis, the morphology of the scorodite changes from rosettes of intergrown crystals to anhedral masses of smaller crystallites. Chemical digestion of the series also became increasingly difficult with increasing Sb content. We conclude that Sb is not taken up in scorodite (perhaps due to its larger ionic radius and different co-ordination with O compared to As), that increasing amounts of Sb in the system affect scorodite morphology, and that tripuhyite is a highly stable and perhaps underestimated Sb-sink.