Numerical study on the influence of diffused soft layer in pH regulated polyelectrolyte-coated Nanopore

Abstract

Electroosmotic flow and its effect are numerically studied in the polyelectrolyte layer-coated cylindrical nanopore. The flow characteristic of the electrokinetic consists of the Nernst–Planck equation for species distribution, the Brinkman modified Navier–Stoke equation for fluid flow and the Poisson equation for induced electric potential. These nonlinear coupled governing equations for potential distribution, ionic species distribution and fluid flow are solved through a finite volume method in staggered grid system for cylindrical coordinate. This study established the importance of the bulk ionic concentration, electrolyte pH, the softness of the polyelectrolyte layer, the nanopore geometries and potential of the polyelectrolyte layer and nanopore wall. Three functional group as Succinoglycan, Glycine, and Proline functional group are considered in this study. The average electroosmotic flow rate increases with polyelectrolyte segment for a fixed pH value in the succinoglycan functional group. The axial velocity increases with the pH values for fixed polyelectrolyte segment. The increase of softness parameter decreases the average flow. The increase in pH values increases the average flow for different bulk ionic concentration. The increase of ionic current with the pH values are more prominent for the negatively charged surface than zero-charged potential. The electric body force increase with the pH values for both zero-charged nanopore and negatively charged nanopore.