New Kinetic Monte Carlo Model to Study the Dissolution of Quartz
New Kinetic Monte Carlo Model to Study the Dissolution of Quartz
复制标题
DOI：
10.1021/acsearthspacechem.0c00303
复制
发表时间：
2021-02-15
影响因子：
3.4
通讯作者：
Manzano, Hegoi
中科院分区：
文献类型：
--
作者：
Martin, Pablo;Gaitero, Juan J.;Manzano, Hegoi
石英溶解作用是地球化学和材料科学中经常发生的过程。它在原子尺度上受硅氧烷键的顺序水解反应和断裂、表面形貌以及固体和溶液之间的吉布斯自由能差G的控制。原子模拟提供了有关石英溶解和反应能垒的有价值的地形信息。然而，按照目前对数据的解释，预测的溶解速率R-Dis和宏观溶解活化能E-a与实验结果之间仍然存在严重的差异。在这项工作中，我们证明了这两个量可以用基于逐键反应的动力学蒙特卡罗(KMC)原子模型来协调，并且R-Dis和E-a可以联合再现。此外，不同石英面的刻蚀坑形状与实验报道的一致：{001}中的V形条纹，{100}中的矩形锥形凹坑，以及{101}中的梯形半锥形凹坑。通过在KMC模型中引入化学可逆性，研究了溶出速率与Delta G的关系，再次得到了与实验相一致的结果。这项工作强调了理解在纳米尺度上发生的机制以描述宏观性质的重要性，并提供了将这项研究扩展到其他矿物和/或溶解条件的基本成分。
Quartz dissolution is a frequent process in geochemistry and materials science. It is controlled at the atomic scale by the sequential hydrolysis reactions and breakage of siloxane bonds, the surface topography, and the Gibbs free energy difference Delta G between the solid and the solution. Atomistic simulations have provided valuable topographic information about quartz dissolution and reaction energy barriers. However, with the current interpretation of the data, serious discrepancies persist between the predicted dissolution rates R-dis and the macroscopic dissolution activation energy E-a compared to their experimental counterparts. In this work we show that both quantities can be reconciled using a kinetic Monte Carlo (KMC) atomistic model based on bond-by-bond reactions and R-dis and E-a can be jointly reproduced. In addition, the obtained etch pit shapes for different quartz planes are in agreement with the experimentally reported ones: V-shape striations in {001}, rectangular pyramidal pits in {100}, and trapezoidal semipyramidal pits in {101}. We also study the dissolution rate dependence with Delta G by introducing chemical reversibility in the KMC model, obtaining again results in good agreement with experiments. This work highlights the importance of understanding the mechanisms taking place at the nanoscale to describe macroscopic properties and provides the basic ingredients to extend this study to other minerals and/or dissolution conditions.