Kinetic Monte Carlo Approach To Study Carbonate Dissolution
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- 作者：Inna Kurganskaya ; Andreas Luttge
- 刊名：Journal of Physical Chemistry C
- 出版年：2016
- 出版时间：March 31, 2016
- 年：2016
- 卷：120
- 期：12
- 页码：6482-6492
- 全文大小：773K
- ISSN：1932-7455
文摘
Reactive properties of carbonate minerals and rocks attract a significant attention with regard to modern environmental and industrial problems, including geologic carbon sequestration, toxic waste utilization, cement clinker production, and the fate of carbonate shell-bearing organisms in acidifying oceans. Despite the ultimate importance of the problem, the number of studies connecting atomistic-scale models to experimental observations is limited. In this work we employ the Kinetic Monte Carlo (KMC) approach to model carbonate dissolution at the nanometer–micron scale range and to access quantitative relationships between the variety of surface reactive sites and experimentally observed spatiotemporal rate variance. The presented KMC model adequately reproduces experimentally observed dissolution patterns and rates. We examine mechanistic and quantitative relationships between site reactivity, atomic step velocity, etch pit evolution dynamics, and macroscopic dissolution rates. The analysis of reactive site statistics shows the leading role of kink sites in the control of the overall rate. The kink site density is closely tied to the controlling types of surface features, for example, straight and curved steps having different structural orientations, as well as their dynamic interaction. Structurally different kink sites and steps bring different contributions to the total rate. The modeling results indicate that rate values depend on the spatial distribution and the type of lattice defects. Greatly inhomogeneous defect distribution commonly observed in natural minerals leads to the orders of magnitude local rate variance. The reason is in the dependence of reactive site density on the local availability of reactive steps sources, for example, screw dislocations. We conclude that upscaling of the atomistic models of carbonate dissolution and macroscopic rate predictions should be done taking into account the entire variety of reactive sites and surface features as well as their spatiotemporal distribution.