Design of Highly Water-Permeable Nanoporous Membrane by Arrangement of Regular Atomic Charges on the Pore-Wall: A Non-Equilibrium Molecular Dynamics Study

Abstract

Non-equilibrium molecular dynamics (NEMD) simulations were employed to investigate the effect of charged pore-wall of carbon nanotubes (CNTs), which is the model of microporous membranes. The study found that the charged atoms on the CNT pore-wall significantly affect how water molecules orient themselves in the pore through the formation of hydrogen bonds with charged pore-wall atoms. Two different atomic charge arrangements on the pore-wall were investigated: a linear arrangement and a double helix arrangement. The latter resulted in a higher flux when tested at higher applied pressure. Additionally, the fluxes in charged pore-wall models were higher than that in uncharged pore-wall models. It is concluded that optimizing charge arrangements could enhance water permeation, which holds potential for improving conventional RO membranes.

Keywords

• Reverse osmosis
• Non-equilibrium molecular dynamics
• Desalination
• Carbon nanotube