Mechano-nanofluidics: water transport through CNTs by mechanical actuation

Abstract

Mechano-nanofluidics, defined as the study of mechanical actuation effects on the properties of nanofluidics, have received broad interest recently in the field of nanofluidics. The coupling between phonons in carbon nanostructures and fluids under confinement is verified to enhance the diffusion of fluids. Especially, carbon nanotubes (CNTs) are applied as perfect nanochannels with fast water mass transport, making them to be one of the next generation of membranes. Here, we investigated water permeation through CNT membranes with the mechanical vibrations using non-equilibrium molecular dynamics simulations. The simulation results reveal that the water flux is highly promoted by a travelling surface waves at 1 THz. The water flux is enhanced by as large as 20 times for the single-file structured water at 20 MPa. The vibration effect is verified to be equivalent to a pressure drop with \({{{\Delta}}}P\) up to 295 MPa. We show that the role of vibration diminishes for water in a larger CNTs. The water structure and hydrogen bond network are analyzed to understand the phenomena. The results of the present work are applied to provide guidance for the development of high-performance membranes.