Nonclassical Behavior in Competitive Ion Adsorption at a Charged Solid–Water Interface
Journal Article
·
· Journal of Physical Chemistry Letters
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Univ. of Delaware, Newark, DE (United States)
Ion adsorption at solid-water interfaces is commonly described by interactions between specific surface sites and adsorbed ions in classical models. However, energetic contributions from non-site-specific ion-ion interactions have not been explored systematically. Here, we report non-classical behaviors observed during competitive adsorption between Sr2+ and Na+/Rb+ at the negatively-charged muscovite mica (001)-water interface, revealing apparent controls of adsorbed ion speciation over the interfacial reactivity. In the absence of competing cations, Sr2+ adsorbs in approximately equivalent proportions of inner-sphere and outer-sphere complexes, whereas it adsorbs predominantly as an outer-sphere complex in the presence of Na+/Rb+. This transformation of adsorbed Sr2+ speciation significantly decreases its adsorption strength, as indicated by ~15-fold shift in the Sr2+ adsorption edge concentration, compared to that calculated from a classical Langmuir isotherm model developed based on site-specific interactions. Finally, these observations highlight the importance of non-site-specific interactions in controlling the energetics of chemical reactions at the charged interface.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1617653
- Journal Information:
- Journal of Physical Chemistry Letters, Journal Name: Journal of Physical Chemistry Letters Journal Issue: 10 Vol. 11; ISSN 1948-7185
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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