Hydrophobic effects on adsorption of solutes onto surfaces

Abstract

This paper describes the adsorption phenomena from the view of hydrophobic effects. Through systematic comparison of molecular dynamics simulation results for aqueous solutions of iodide and lithium particles (charged and uncharged), we conclude that the adsorption process is primarily governed by the size of the solute, which is an entropy effect, and the strength of the solute-solvent interaction, which reflects enthalpy variations. Because of the entropy effect, solutes have a tendency to adsorb onto electrodes. This tendency is opposed to the enthalpy effect which promotes hydrations. The adsorption is a process to minimize the free energy change. Surface polarization and external electric field affect the solvent structure and have an indirect influence on the neutral adsorbates. In all the cases studied here, the contact pair of a neutral sphere and a flat wall appears to be the most stable configuration. © 1995.