Simple, Reproducible Synthesis of Pure Monohydrocalcite with Low Mg Content
Simple, Reproducible Synthesis of Pure Monohydrocalcite with Low Mg Content
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DOI：
10.3390/min10040346
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发表时间：
2020-04
期刊：
影响因子：
2.5
通讯作者：
Takuma Kitajima;K. Fukushi;M. Yoda;Y. Takeichi;Y. Takahashi
中科院分区：
文献类型：
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作者：
Takuma Kitajima;K. Fukushi;M. Yoda;Y. Takeichi;Y. Takahashi
单水方解石（MHC）是一种亚稳的含水碳酸钙，在实验室中形成时需要母液中的镁。以往报道的方法制备的MHC总是含有大量的镁（Mg/Ca比高达0.4），因为在合成过程中同时形成无定形碳酸镁，这阻碍了详细阐明MHC的矿物学特征。在此，我们在低温（5 °C）下合成了MHC，发现它含有很少的Mg（Mg/Ca比< 0.01）。合成MHC的X射线吸收近边结构分析表明，存在的镁在结构上并入MHC中，并且这种镁的化学形态与文石中的镁相似。因此，低温合成是生产MHC而不产生无定形碳酸镁的有效手段。
Monohydrocalcite (MHC) is a metastable hydrous calcium carbonate that requires Mg in the mother solution during formation in the laboratory. MHC prepared by previously reported methods always contains a large amount of Mg (Mg/Ca ratio up to 0.4) because of the simultaneous formation of amorphous Mg carbonate during synthesis, which has hindered detailed elucidation of the mineralogical characteristics of MHC. Here, we synthesized MHC at low temperature (5 °C) and found that it contained little Mg (Mg/Ca ratio < 0.01). X-ray absorption near-edge structure analysis of synthesized MHC revealed that the Mg present was structurally incorporated within the MHC, and that the chemical speciation of this Mg was similar to that of Mg in aragonite. Thus, low-temperature synthesis is an effective means of producing MHC without also producing amorphous Mg carbonate.