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.