Title: Transverse ion diffusion inside fixed charge narrow pores
Authors: B.Sulbarán (Grupo de Química Teórica Quimicofísica de Fluidos y Fenómenos Interfaciales (QUIFFIS), Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela; Departamento de Investigación, Area de Ciencias Aplicadas, Instituto Universitario Tecnológico de Ejido (IUTE), Ejido, Venezuela), W.Olivares-Rivas, P.J.Colmenares (Grupo de Química Teórica Quimicofísica de Fluidos y Fenómenos Interfaciales (QUIFFIS), Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela)

The diffusion dynamics of ions inside a planar slit with a high constant surface charge density was studied by solving the Smoluchowski/Hypernneted-Chain equation for the mean first passage times. The behavior of local properties, such as the potential of mean force, is correlated with the time it takes for an ion to get adsorbed at the surface, and also with macroscopic properties like the salt rejection coefficient and the apparent diffusion constant in porous media, as a function of pore size. We show that the width of the walls has an important effect on the transverse ion diffusion process.

Key words: ion diffusion, charged micro-pores, mean first passage time, apparent transverse diffusion constant
PACS: 05.20.Jj, 82.65.+r