Electrostatic Analysis for Osmotic Flow through Rectangular Channels

Abstract

An electrostatic model for osmotic flow through channels with surface charges is developed to understand the contribution of electrical charges to the transport of solution through narrow channels. The interaction energy between surface charges of the solute and the channel wall is used to express the osmotic reflection coefficient as a function of the surface charges, the ion concentration of the fluid, and the size ratio of the solute to the channel. Our model predicts that even for small Debye length compared to the channel size, the surface charges could significantly increase the osmotic flow, when the charges of the solute and the channel wall have the same sign.