Perry Thomas D, Duckworth Owen W, Kendall Treavor A, Martin Scot T, Mitchell Ralph
Harvard University, Division of Engineering and Applied Sciences, Pierce Hall, Cambridge, Massachusetts 02138, USA.
J Am Chem Soc. 2005 Apr 27;127(16):5744-5. doi: 10.1021/ja042737k.
Ethylenediamine tetraacetate (EDTA)-mediated calcite dissolution occurs via a different process than water-promoted dissolution. Near-atomic-scale observations in EDTA solutions demonstrate that, after penetration through a critical pit depth barrier, step velocity increases linearly with pit depth for EDTA-promoted dissolution. The parallel processes of water-dominated dissolution at point defects and ligand-dominated dissolution at linear defects are clearly observable in real-time atomic force micrographs. EDTA and water initiate and propagate dissolution steps with pit-depth-dependent and -independent step velocities, respectively. The linear defects are susceptible to continuously increasing step velocities, but the point defects are not. The findings update the conceptual framework of the microscopic mechanism of mineral dissolution.
乙二胺四乙酸（EDTA）介导的方解石溶解过程与水促进的溶解过程不同。在EDTA溶液中的近原子尺度观察表明，在穿透临界蚀坑深度屏障后，对于EDTA促进的溶解，台阶速度随蚀坑深度呈线性增加。在实时原子力显微镜图像中可以清楚地观察到点缺陷处水主导的溶解和平行线缺陷处配体主导的溶解这两个并行过程。EDTA和水分别以与蚀坑深度相关和无关的台阶速度引发并推进溶解步骤。平行线缺陷容易受到不断增加的台阶速度的影响，但点缺陷则不然。这些发现更新了矿物溶解微观机制的概念框架。
