Behaviors of sodium and calcium ions at the borosilicate glass-water interface: Gaining new insights through an ab initio molecular dynamics study

• Main Authors: Charpentier, T. (Author), Delaye, J.-M (Author), Gin, S. (Author), Jabraoui, H. (Author), Pollet, R. (Author)
• Format: Article
• Language: English
• Published: American Institute of Physics Inc. 2022
• Subjects: Ab initio molecular dynamics; Ab initio molecular dynamics simulation; Borosilicate glass; Calcium compounds; Calcium ions; Calculations; Cation vacancies; Density functional theory; Different mechanisms; Dynamic studies; Glass-water interface; Molecular dynamics; Positive ions; Simulation time; Sodium compounds; Sodium ions; Water interface
• Online Access: View Fulltext in Publisher

 We study reactivity and leaching at the calcium sodium borosilicate (CNBS)-water interface by means of a Car-Parrinello ab initio molecular dynamics simulation over a simulation time of 100 ps. With an emphasis on the comparison between the behaviors of Ca2+ and Na+ cations at the CNBS glass-water interface, different mechanism events during the trajectory are revealed, discussed, and correlated with other density functional theory calculations. We show that Na+ ions can be released in solution, while Ca2+ cannot leave the surface of CNBS glass. This release is correlated with the vacancy energy of Ca2+ and Na+ cations. Here, we found that the CNBS structure with the Na+ cation vacancy is energetically more favorable than the structure with the Ca2+ cation vacancy. The calcium adsorption site has been shown to have a greater affinity for water than can be found in the case of the sodium site, demonstrating that affinity may not be considered a major factor controlling the release of cations from the glass to the solution. © 2022 Author(s).