Li Yunjian, Pan Hui, Liu Qing, Ming Xing, Li Zongjin
Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR, 999078, P. R. China.
Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macao SAR, 999078, P. R. China.
Nat Commun. 2022 Mar 10;13(1):1253. doi: 10.1038/s41467-022-28932-2.
Dissolution of minerals in water is ubiquitous in nature and industry, especially for the calcium silicate species. However, the behavior of such a complex chemical reaction is still unclear at atomic level. Here, we show that the ab initio molecular dynamics and metadynamics simulations enable quantitative analyses of reaction pathways, thermodynamics and kinetics of the calcium ion dissolution from the tricalcium silicate (CaSiO) surface. The calcium sites with different coordination environments lead to different reaction pathways and free energy barriers. The low free energy barriers result in that the detachment of the calcium ion is a ligand exchange and auto-catalytic process. Moreover, the water adsorption, proton exchange and diffusion of water into the surface layer accelerate the leaching of the calcium ion from the surface step by step. The discovery in this work thus would be a landmark for revealing the mechanism of tricalcium silicate hydration.
矿物在水中的溶解在自然界和工业中普遍存在，尤其是对于硅酸钙类物质。然而，这种复杂化学反应在原子层面的行为仍不清楚。在此，我们表明，从头算分子动力学和元动力学模拟能够对硅酸三钙（CaSiO）表面钙离子溶解的反应路径、热力学和动力学进行定量分析。具有不同配位环境的钙位点导致不同的反应路径和自由能垒。低自由能垒使得钙离子的脱离是一个配体交换和自催化过程。此外，水的吸附、质子交换以及水向表面层的扩散逐步加速了钙离子从表面的浸出。因此，这项工作中的发现将成为揭示硅酸三钙水化机理的一个里程碑。
