Ion enrichment on the hydrophobic carbon-based surface in aqueous salt solutions due to cation-? interactions.

ABSTRACT: By incorporating cation-? interactions to classic all-atoms force fields, we show that there is a clear enrichment of Na(+) on a carbon-based ? electron-rich surface in NaCl solutions using molecular dynamics simulations. Interestingly, Cl(-) is also enriched to some extend on the surface due to the electrostatic interaction between Na(+) and Cl(-), although the hydrated Cl(-)-? interaction is weak. The difference of the numbers of Na(+) and Cl(-) accumulated at the interface leads to a significant negatively charged behavior in the solution, especially in nanoscale systems. Moreover, we find that the accumulation of the cations at the interfaces is universal since other cations (Li(+), K(+), Mg(2+), Ca(2+), Fe(2+), Co(2+), Cu(2+), Cd(2+), Cr(2+), and Pb(2+)) have similar adsorption behaviors. For comparison, as in usual force field without the proper consideration of cation-? interactions, the ions near the surfaces have a similar density of ions in the solution.

SUBMITTER: Shi G 

PROVIDER: S-EPMC3853681 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature