Attainment of a High Concentration of Salt Ions Near a Metallic or Dielectric Wall in a Salt Solution as a result of Electrical Image Forces

Electrical image potentials near a metallic wall or near a dielectric wall of higher dielectric constant than that of the solution are attractive, and therefore, can concentrate salt ions near the wall. This opens the possibility that they can be used to concentrate salt water, producing brine, and even desalinating salt water. It has recently been observed that near a metallic surface, ions in room temperature ionic liquids precipitate (but not near a nonmetallic surface). A likely reason for why precipitation of ions in salt water, as a result of electrical image forces, has not as yet been observed is the existence of an energy barrier near a solid surface, resulting from the reduction of ion solvation as a result of the large decrease of the dielectric constant of water within 0.75nm and normal to a solid wall. We will explore the conditions under which ions are able to get past this barrier and concentrate at a solid wall, either as a result of thermal activation over the solvation energy potential barrier or as a result of a reduction of this barrier caused by screening due to the ions.