title: Mean-field theory for inhomogeneous electrolytes.
abstract: We calculate the free energy density for inhomogeneous electrolytes based on the mean-field Debye-Hückel theory. Derived are the contributions of (1) the differential term for the electrolyte density being slow varying in one direction and (2) the boundary term for an electrolyte confined to one side of a planar interface. These contributions are shown to cause an electrolyte depletion near the air-water interfaces, which makes the surface tension increase, to be significantly larger than those predicted by previous theories. Nonuniform electrolyte densities are also computed near the water-electrolyte and electrolyte-electrolyte interfaces. Finally we calculate the interaction of two uncharged macrospheres due to the electrolyte depletion.
authors.affiliation: Department of Physics and Center for Complex Systems, National Central University, Chungli 320, Taiwan.
authors.forename: Shin-Shing
authors.initials: SS
authors.lastname: Yeh
authors.forename: Peilong
authors.initials: P
authors.lastname: Chen