3 years ago

Molecular Dynamics Simulations of Quartz (101)–Water and Corundum (001)–Water Interfaces: Effect of Surface Charge and Ions on Cation Adsorption, Water Orientation, and Surface Charge Reversal

Molecular Dynamics Simulations of Quartz (101)–Water and Corundum (001)–Water Interfaces: Effect of Surface Charge and Ions on Cation Adsorption, Water Orientation, and Surface Charge Reversal
Roberto E. Rozas, Gonzalo R. Quezada, Pedro G. Toledo
Quartz and corundum surfaces in water are capable of adsorbing and releasing protons, a behavior attributed to the amphoteric character of their silanol and ab initio calculations are used to obtain different charge densities on crystalline (101) quartz and (001) corundum surfaces and the corresponding charge delocalization after deprotonation of the silanol and aluminol groups, respectively. Then, classical molecular dynamics simulations are used to study the interaction of water with the charged quartz and corundum surfaces in the presence of aqueous solutions of monovalent alkali and alkaline-earth metal chlorides. Results include density profiles of adsorbed cations, and the effect of cations on the orientation profiles of water molecules close to the mineral surfaces and the distance at which such surfaces become neutral or reverse their charges. In all cases where there are experimental or simulation data, the results here compare very well. The adsorption density of cations on quartz increases with the size of the cations, either monovalent or divalent. The density of adsorbed monovalent cations on corundum decreases for larger cation sizes, while this behavior on quartz is the opposite. In both cases the adsorption of cations is enhanced by the increase of the surface charge. Adsorption on corundum is much more extensive compared to that on quartz for all surface charges and cations. The sequence of simulations of cation adsorption on silica and alumina provide support to the idea that high isoelectric point materials preferentially adsorb well-hydrated cations and low isoelectric point materials preferentially adsorb poorly hydrated cations. The results of this work are expected to contribute to improving current knowledge on the interaction of mineral oxides with macromolecules, such as polyelectrolytes in solid–liquid separation processes and biomolecules in lung inflammatory processes.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b08836

DOI: 10.1021/acs.jpcc.7b08836

You might also like
Never Miss Important Research

Researcher is an app designed by academics, for academics. Create a personalised feed in two minutes.
Choose from over 15,000 academics journals covering ten research areas then let Researcher deliver you papers tailored to your interests each day.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.