Interfacial Energies for Heterogeneous Nucleation of Calcium Carbonate on Mica and Quartz

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• 作者：Qingyun Li ; Alejandro Fernandez-Martinez ; Byeongdu Lee ; Glenn A. Waychunas ; Young-Shin Jun
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：May 20, 2014
• 年：2014
• 卷：48
• 期：10
• 页码：5745-5753
• 全文大小：435K
• 年卷期：v.48,no.10(May 20, 2014)
• ISSN：1520-5851

文摘

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 (伪鈥?. Ex situ Raman spectroscopy identified both calcite and vaterite as CaCO₃ polymorphs; however, vaterite is the most probable heterogeneous nuclei mineral phase. The 伪鈥?was 24 mJ/m² for the vaterite鈥搈ica system and 32 mJ/m² for the vaterite鈥搎uartz system. The smaller 伪鈥?of the CaCO₃鈥搈ica system led to smaller particles and often higher particle densities on mica. A contributing factor affecting 伪鈥?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.