Reconsidering Calcium Dehydration as the Rate-Determining Step in Calcium Mineral Growth.
| Autor: | Koskamp JA; Department of Earth Sciences-Geochemistry, Utrecht University, 3584 CB Utrecht, The Netherlands., Ruiz-Hernandez SE; Department of Earth Sciences-Geochemistry, Utrecht University, 3584 CB Utrecht, The Netherlands., Di Tommaso D; Materials Research Institute and School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, E1 4NS London, United Kingdom., Elena AM; Daresbury Laboratory, STFC, Daresbury WA4 4AD, United Kingdom., De Leeuw NH; Department of Earth Sciences-Geochemistry, Utrecht University, 3584 CB Utrecht, The Netherlands.; School of Chemistry, Cardiff University, Main Building Park Place, Cardiff CF10 3AT, United Kingdom., Wolthers M; Department of Earth Sciences-Geochemistry, Utrecht University, 3584 CB Utrecht, The Netherlands. |
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| Jazyk: | angličtina |
| Zdroj: | The journal of physical chemistry. C, Nanomaterials and interfaces [J Phys Chem C Nanomater Interfaces] 2019 Nov 07; Vol. 123 (44), pp. 26895-26903. Date of Electronic Publication: 2019 Oct 16. |
| DOI: | 10.1021/acs.jpcc.9b06403 |
| Abstrakt: | 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. Competing Interests: The authors declare no competing financial interest. (Copyright © 2019 American Chemical Society.) |
| Databáze: | MEDLINE |
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