Enhanced Ion Adsorption on Mineral Nanoparticles
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Classical molecular dynamics simulation was used to study the adsorption of Na+, Ca2+, Ba2+ and Cl-ions on gibbsite edge (1 0 0), basal (0 0 1), and nanoparticle surfaces. The gibbsite nanoparticle consists of both basal and edge surfaces. Simulation results indicate that Na+ and Cl- ions adsorb on both (1 0 0) and (0 0 1) surfaces as inner-sphere species (i.e., no water molecules between an ion and the surface). Outer-sphere Cl- ions (i.e., one water molecule between an ion and the surface) were also found on these surfaces. On the (1 0 0) edge, Ca2+ ions adsorb as inner-sphere and outer-sphere complexes, while on the (0 0 1) surface outer-sphere Ca2+ions are the dominant species. Ba2+ ions were found as inner-sphere and outer-sphere complexes on both surfaces. Calculated ion surface coverages indicate that, for all ions, surface coverages are always higher on the basal surface compared to the edge surface. More importantly, surface coverages for cations on the gibbsite nanoparticle are always higher than those calculated for (1 0 0) and (0 0 1) surfaces. This enhanced ion adsorption behavior for the nanoparticle is due to the significant number of inner-sphere cations found at nanoparticle corners. Outer-sphere cations do not contribute to the enhanced surface coverage. In addition, there is no ion adsorption enhancement observed for the Cl- ion. Our work provides a molecular-scale understanding of the relative significance of ion adsorption onto gibbsite basal versus edge surfaces and demonstrates the corner effect on ion adsorption on nanoparticles.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC04-94AL85000; NA0003525
- OSTI ID:
- 1644070
- Alternate ID(s):
- OSTI ID: 1473941
- Report Number(s):
- SAND-2020-7115J; SAND-2018-9865J; 687298
- Journal Information:
- Langmuir, Vol. 34, Issue 20; ISSN 0743-7463
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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