Interfacial Energies for Heterogeneous Nucleation of Calcium Carbonate on Mica and Quartz
Interfacial Energies for Heterogeneous Nucleation of Calcium Carbonate on Mica and Quartz
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DOI：
10.1021/es405141j
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发表时间：
2014-05-20
影响因子：
11.4
通讯作者：
Jun, Young-Shin
中科院分区：
文献类型：
--
作者：
Li, Qingyun;Fernandez-Martinez, Alejandro;Jun, Young-Shin
界面自由能通常控制碳酸钙（CaCO 3）在矿物表面的非均质成核。在这里，我们报告了在云母（白云母）和石英，这使我们能够获得的界面能管理异质成核碳酸钙成核的原位实验研究。采用掠入射小角X射线散射（GISAXS）方法测量了不同过饱和度下的成核速率。将速率并入经典成核理论以计算有效界面能（α '）。非原位拉曼光谱鉴定方解石和球文石作为碳酸钙多晶型物;然而，球文石是最可能的异质核矿物相。球霰石云母系统的α '为24 mJ/m2，球霰石石英系统的α'为32 mJ/m2。CaCO 3云母系统的较小α '导致云母上的较小颗粒和通常较高的颗粒密度。在我们的系统中，影响α '的一个因素是CaCO 3和云母之间的结构失配比CaCO 3和石英之间的结构失配小。的亲水性和表面电荷的程度不能解释所观察到的碳酸钙成核云母和石英的趋势。这项研究的结果提供了新的热力学参数的地下反应输运建模，并有助于我们了解的机制，表面上的碳酸钙形成的关注。
Interfacial free energies often control heterogeneous nucleation of calcium carbonate (CaCO3) on mineral surfaces. Here we report an in situ experimental study of CaCO3 nucleation on mica (muscovite) and quartz, which allows us to obtain the interfacial energies governing heterogeneous nucleation. In situ grazing incidence small-angle X-ray scattering (GISAXS) was used to measure nucleation rates at different supersaturations. The rates were incorporated into classical nucleation theory to calculate the effective interfacial energies (alpha'). Ex situ Raman spectroscopy identified both calcite and vaterite as CaCO3 polymorphs; however, vaterite is the most probable heterogeneous nuclei mineral phase. The alpha' was 24 mJ/m(2) for the vaterite mica system and 32 mJ/m(2) for the vaterite quartz system. The smaller alpha' of the CaCO3 mica system led to smaller particles and often higher particle densities on mica. A contributing factor affecting alpha' in our system was the smaller structural mismatch between CaCO3 and mica compared to that between CaCO3 and quartz. The extent of hydrophilicity and the surface charge could not explain the observed CaCO3 nucleation trend on mica and quartz. The findings of this study provide new thermodynamic parameters for subsurface reactive transport modeling and contribute to our understanding of mechanisms where CaCO3 formation on surfaces is of concern.