Ion transport through single-walled carbon nanotubes: Effects of electric field and fixed surface charge

Abstract

We investigate the ion permeation trends for an aqueous sodium chloride solution through negatively charged carbon nanotubes under the simultaneous effects of a concentration gradient and an electric field using Molecular Dynamics simulations. A two-stage ion transport process was observed that resulted in a tunable effective ion flux toward the low concentration reservoir wherein the first stage resembled an electric-field assisted counter-ion (sodium) migration to the downstream reservoir for a short period of time followed by a second stage consisting of diffusion-driven electrolyte transport governed by the strength of the Donnan potential formed by the fixed charge on the nanotube.