Reconsidering calcium dehydration as the rate-determining step in calcium mineral growth
| Autor: | Koskamp, Janou A., Ruiz-Hernandez, Sergio E., Di Tommaso, Devis, Elena, Alin Marin, De Leeuw, Nora H., Wolthers, Mariette, Geochemistry of Earth materials, Geochemistry |
|---|---|
| Přispěvatelé: | Geochemistry of Earth materials, Geochemistry |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Ab initio
chemistry.chemical_element Thermodynamics 02 engineering and technology Neutron scattering Calcium 010402 general chemistry 01 natural sciences Article Coatings and Films Molecular dynamics Energy(all) Electronic medicine Optical and Magnetic Materials Dehydration Physical and Theoretical Chemistry Dissolution 021001 nanoscience & nanotechnology Alkali metal medicine.disease Rate-determining step 0104 chemical sciences Electronic Optical and Magnetic Materials Surfaces Coatings and Films Surfaces General Energy chemistry 0210 nano-technology |
| Zdroj: | The Journal of Physical Chemistry. C, Nanomaterials and Interfaces Journal of Physical Chemistry C, 123(44), 26895. American Chemical Society |
| ISSN: | 1932-7447 |
| Popis: | The dehydration of cations is generally accepted as the rate-limiting step in many processes. Molecular dynamics (MD) can be used to investigate the dynamics of water molecules around cations, and two different methods exist to obtain trajectory-based water dehydration frequencies. Here, these two different post-processing methods (direct method versus survival function) have been implemented to obtain calcium dehydration frequencies from a series of trajectories obtained using a range of accepted force fields. None of the method combinations reproduced the commonly accepted experimental water exchange frequency of 10-8.2 s-1. Instead, our results suggest much faster water dynamics, comparable with more accurate ab initio MD simulations and with experimental values obtained using neutron scattering techniques. We obtained the best agreement using the survival function method to characterize the water dynamics, and we show that different method combinations significantly affect the outcome. Our work strongly suggests that the fast water exchange kinetics around the calcium ions is not rate-limiting for reactions involving dissolved/solvated calcium. Our results further suggest that, for alkali and most of the earth alkali metals, mechanistic rate laws for growth, dissolution, and adsorption, which are based on the principle of rate-limiting cation dehydration, need careful reconsideration. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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