Properties of alkali-halide salt solutions about polarizable nanoparticle solutes for different ion models

We investigate the distributions of various salts about large hydrophobic polarizable solutes in aqueous electrolyte solutions. The solutes are modeled as nanometer-sized cylindrical objects, a scale relevant to biomolecules and nanomaterials, and particularly high aspect ratio nanoparticles. Interactions, including image charge forces arising from the finite polarizability of the solute, between explicit solvent/ions and the solute are computed explicitly using a molecular dynamics simulation methodology we have recently introduced. Comparisons are made between several salt species and different models of the force fields for each ionic component of the salt. We find evidence that both small cations, Li+, and large anions, I-, adsorb at hydrophobic interfaces. Our results indicate that the ion structure about the solute is strongly dependent on the force field investigated, suggesting that ion selectivity is quite sensitive to the respective parameters defining the ion's size and binding energy as well as to the polarizability of the solute. (c) 2010 American Institute of Physics. [doi:10.1063/1.3499871]